Title:
MULTIPLE-SWITCH BANK AND KEYBOARD
United States Patent 3627935
Abstract:
A multiple-switch bank is provided that generates a unique group of electrical pulses at each switch whereby each group of pulses represents a specific bit of intelligence or information to be coded and transmitted. Coding is accomplished by providing at each switch a plurality of contacts which can be brought into engagement with an equal number of code bars. Some bars are coated with a nonconductive layer whereby at the remaining bars there can be established a unique pattern of conductive electrical contacts. The switches are manually operated from a keyboard of novel design in which the keys may be arranged in the conventional pattern of a typewriter. The block with the code bars can be removed and replaced by another one in order to reprogram all the coded signals. The signals are particularly compatible with receiving equipment adapted to operate on binary codes.
US Patent References:
Telephone apparatus
Wise - October 1932 - 1882106
Multiple switch and the like
Flynt - June 1943 - 2320774
Multisurface cross point switching mechanisms
Grunfelder et al. - February 1964 - 3120584
Data encoding keyboard
Willcox et al. - December 1966 - 3290439
Telephone apparatus
Wise - October 1932 - 1882106
Multiple switch and the like
Flynt - June 1943 - 2320774
Multisurface cross point switching mechanisms
Grunfelder et al. - February 1964 - 3120584
Data encoding keyboard
Willcox et al. - December 1966 - 3290439
Application Number:
05/012735
Publication Date:
12/14/1971
Filing Date:
02/19/1970
View Patent Images:
Export Citation:
Primary Class:
Other Classes:
200/5A, 200/86R, 200/512, 341/34
International Classes:
H01H13/70; H01H9/26; H01H3/02
Field of Search:
179/9K,90.3 200/1,5,83.5,86.1,86R,86A,172R 235/145R
Primary Examiner:
Scott J. R.
Claims:
I claim
1. A multiple-switch bank for producing a unique group of electric signals for each of a plurality of individual bits of intelligence, comprising operatively assembled in combination: a keyboard comprising a single sheet of flexible material having a separate movable key for each bit; each of said keys comprising an integral portion of said single sheet and separated therefrom by a looplike slot the opposite ends of which extend along the opposite sides of a hinge tang having one end integral with said sheet; and means moved by and responsive to deflection of a key of the keyboard to establish a unique pattern of electrical contacts with a plurality of conductors, each of which contacts produces an electrical signal in a conductor and which signal is isolated from said movable keys.
2. A multiple-switch bank as in claim 1 characterized in that said hinge tang includes a straight groove extending transversely thereof.
3. A multiple-switch bank as in claim 1 characterized in that said means for establishing a unique pattern of contacts comprises: a plurality of electrically isolated conductors; a contact assembly having a plurality of movable contacts each associated with one key and supported resiliently at a normal position spaced from a respective one of said conductors but movable toward and away from said conductors by movement of the associated key; and signal group control means associated with the movable contacts for each of said keys effective to establish a unique group of electrical signals in response to depression of each of said keys
4. A multiple-switch bank as in claim 3 characterized in the provision of a plurality of said signal group control means for establishing unique groups of electrical signals, and means for selectively shifting said signal group control means whereby depression of a selected key creates a peculiar group of electrical signals depending upon which of said signal control group means is in use.
5. A multiple-switch bank as in claim 3 in which an area of selected conductors is coated with an insulating material to prevent electrically conductive contact; said movable contacts at selected locations in order to establish each unique pattern of electrical signals.
6. A multiple-switch bank as in claim 3 characterized in that said contact assemblies are integral with and part of a common homogenous sheet of flexible conductive material, each contact assembly having a plurality of similar flexible fingers each aligned with a respective one of said conductors and deflectable in unison by an associated one of said keys toward said conductors.
7. A multiple-switch bank as in claim 3 characterized in that each contact assembly is an articulated member comprising: a flexible strip hingedly mounted at one end and terminating at the opposite end in a plurality of integral fingers, there being one finger for each of said conductors.
8. A multiple-switch bank as in claim 1 characterized in that said movable keys are arranged in at least one row and said means to establish a unique pattern of electrical contacts comprises: a plurality of fixed conductors extending parallel to and spaced from the row of key; and a plurality of resiliently mounted movable contacts arranged between each of said keys and said conductors, there being a movable contact for each of said conductors associated with and movable by each key toward and away from engagement with said conductors.
9. A multiple-switch bank as in claim 3 characterized in the provision of a rigid guide plate supported beneath and parallel to said flexible keyboard sheet, and a plurality of transfer pins slidably mounted in said guide plate with their opposite ends bearing against associated ones of said keys and said contact assemblies and individually movable in response to movement of an associated one of said keys.
10. A multiple-switch bank as in claim 1 in which said plurality of conductors and said means for establishing a unique pattern of electrical contacts includes means for changing the pattern of electrical contacts.
11. A multiple-switch bank that comprises operatively assembled in combination: a keyboard having a plurality of independently operable resilient keys fixed to a first sheet; a second and conductive flexible sheet having a plurality of groups of movable contacts each group of which is movable in unison by an associated one of said keys, a code block operatively associated with said groups of contacts and including said plurality of conductors and means associated therewith for establishing a unique pattern of electrical signals each time a key is depressed to complete an electric circuit between certain of said movable contacts and certain of said conductors, and means for shifting said code block to an alternate position to change the pattern of conductive contacts between each of said groups of contacts and said plurality of conductors.
12. A multiple-switch bank as in claim 11 characterized in that said code block is readily replaceable with a code block providing a different unique pattern of electrical signals at each key.
13. A multiple-switch bank as in claim 11 characterized in that said code block has a base of nonconducting material fixedly supporting said conductors in spaced-apart parallel relation, selected areas of certain of said conductors opposite each group of movable contacts being covered with insulating means positioned to prevent formation of an electrically conductive contact between that conductor and an associated one of said movable contacts.
14. An article of manufacture suitable for use in opening and closing an electrical circuit not in circuit with said article of manufacture, said article comprising a thin sheet of resilient material having a relatively large area key portion separated from the remainder of said sheet except for a relatively small area hinge tang confined to one lateral side of said key portion, said hinge tang being integral with both said sheet and with said key portion and effective to restore said key portion repeatedly to the normal position thereof each time after said key portion has been deflected from said normal position to control an electric circuit not in circuit with said article of manufacture.
15. An article of manufacture as defined in claim 14 characterized in that the normal position of said key portion is generally in the plane of said sheet of resilient material.
16. An article of manufacture as defined in claim 14 characterized in that said key portion has a surface area at least coextensive in size with the tip of an operator's fingertip.
17. An article of manufacture as defined in claim 14 characterized in the provision of housing means supporting said sheet of resilient material and including said sheet as one exposed surface of said housing means.
18. An article of manufacture as defined in claim 17 characterized in the provision within said housing means of a plurality of electrical conductors normally out of conducting contact with one another and operatively associated with said key portion for movement into conducting contact so long as said key portion is held flexed out of the normal position thereof in a predetermined contact closing direction.
19. An article of manufacture as defined in claim 14 characterized in that said sheet of resilient material is provided with a plurality of said key portions each similarly integral with said sheet through similar hinge tangs.
20. An article of manufacture as defined in claim 19 characterized in that said key portions are bordered by a narrow generally C-shaped slot electroetched through said sheet and having the slot ends terminating at the lateral edges of said hinge tang.
21. An article of manufacture as defined in claim 19 characterized in that a plurality of said hinge tangs have substantially identical flexing characteristics and whereby substantially identical touch pressure applied to each by the tip of an operator's finger suffices to bring said plurality of electrical conductors associated with the depressed one of
22. An article of manufacture as defined in claim 27 characterized in that said shifting means includes electromechanical means controlled by flexing
1. A multiple-switch bank for producing a unique group of electric signals for each of a plurality of individual bits of intelligence, comprising operatively assembled in combination: a keyboard comprising a single sheet of flexible material having a separate movable key for each bit; each of said keys comprising an integral portion of said single sheet and separated therefrom by a looplike slot the opposite ends of which extend along the opposite sides of a hinge tang having one end integral with said sheet; and means moved by and responsive to deflection of a key of the keyboard to establish a unique pattern of electrical contacts with a plurality of conductors, each of which contacts produces an electrical signal in a conductor and which signal is isolated from said movable keys.
2. A multiple-switch bank as in claim 1 characterized in that said hinge tang includes a straight groove extending transversely thereof.
3. A multiple-switch bank as in claim 1 characterized in that said means for establishing a unique pattern of contacts comprises: a plurality of electrically isolated conductors; a contact assembly having a plurality of movable contacts each associated with one key and supported resiliently at a normal position spaced from a respective one of said conductors but movable toward and away from said conductors by movement of the associated key; and signal group control means associated with the movable contacts for each of said keys effective to establish a unique group of electrical signals in response to depression of each of said keys
4. A multiple-switch bank as in claim 3 characterized in the provision of a plurality of said signal group control means for establishing unique groups of electrical signals, and means for selectively shifting said signal group control means whereby depression of a selected key creates a peculiar group of electrical signals depending upon which of said signal control group means is in use.
5. A multiple-switch bank as in claim 3 in which an area of selected conductors is coated with an insulating material to prevent electrically conductive contact; said movable contacts at selected locations in order to establish each unique pattern of electrical signals.
6. A multiple-switch bank as in claim 3 characterized in that said contact assemblies are integral with and part of a common homogenous sheet of flexible conductive material, each contact assembly having a plurality of similar flexible fingers each aligned with a respective one of said conductors and deflectable in unison by an associated one of said keys toward said conductors.
7. A multiple-switch bank as in claim 3 characterized in that each contact assembly is an articulated member comprising: a flexible strip hingedly mounted at one end and terminating at the opposite end in a plurality of integral fingers, there being one finger for each of said conductors.
8. A multiple-switch bank as in claim 1 characterized in that said movable keys are arranged in at least one row and said means to establish a unique pattern of electrical contacts comprises: a plurality of fixed conductors extending parallel to and spaced from the row of key; and a plurality of resiliently mounted movable contacts arranged between each of said keys and said conductors, there being a movable contact for each of said conductors associated with and movable by each key toward and away from engagement with said conductors.
9. A multiple-switch bank as in claim 3 characterized in the provision of a rigid guide plate supported beneath and parallel to said flexible keyboard sheet, and a plurality of transfer pins slidably mounted in said guide plate with their opposite ends bearing against associated ones of said keys and said contact assemblies and individually movable in response to movement of an associated one of said keys.
10. A multiple-switch bank as in claim 1 in which said plurality of conductors and said means for establishing a unique pattern of electrical contacts includes means for changing the pattern of electrical contacts.
11. A multiple-switch bank that comprises operatively assembled in combination: a keyboard having a plurality of independently operable resilient keys fixed to a first sheet; a second and conductive flexible sheet having a plurality of groups of movable contacts each group of which is movable in unison by an associated one of said keys, a code block operatively associated with said groups of contacts and including said plurality of conductors and means associated therewith for establishing a unique pattern of electrical signals each time a key is depressed to complete an electric circuit between certain of said movable contacts and certain of said conductors, and means for shifting said code block to an alternate position to change the pattern of conductive contacts between each of said groups of contacts and said plurality of conductors.
12. A multiple-switch bank as in claim 11 characterized in that said code block is readily replaceable with a code block providing a different unique pattern of electrical signals at each key.
13. A multiple-switch bank as in claim 11 characterized in that said code block has a base of nonconducting material fixedly supporting said conductors in spaced-apart parallel relation, selected areas of certain of said conductors opposite each group of movable contacts being covered with insulating means positioned to prevent formation of an electrically conductive contact between that conductor and an associated one of said movable contacts.
14. An article of manufacture suitable for use in opening and closing an electrical circuit not in circuit with said article of manufacture, said article comprising a thin sheet of resilient material having a relatively large area key portion separated from the remainder of said sheet except for a relatively small area hinge tang confined to one lateral side of said key portion, said hinge tang being integral with both said sheet and with said key portion and effective to restore said key portion repeatedly to the normal position thereof each time after said key portion has been deflected from said normal position to control an electric circuit not in circuit with said article of manufacture.
15. An article of manufacture as defined in claim 14 characterized in that the normal position of said key portion is generally in the plane of said sheet of resilient material.
16. An article of manufacture as defined in claim 14 characterized in that said key portion has a surface area at least coextensive in size with the tip of an operator's fingertip.
17. An article of manufacture as defined in claim 14 characterized in the provision of housing means supporting said sheet of resilient material and including said sheet as one exposed surface of said housing means.
18. An article of manufacture as defined in claim 17 characterized in the provision within said housing means of a plurality of electrical conductors normally out of conducting contact with one another and operatively associated with said key portion for movement into conducting contact so long as said key portion is held flexed out of the normal position thereof in a predetermined contact closing direction.
19. An article of manufacture as defined in claim 14 characterized in that said sheet of resilient material is provided with a plurality of said key portions each similarly integral with said sheet through similar hinge tangs.
20. An article of manufacture as defined in claim 19 characterized in that said key portions are bordered by a narrow generally C-shaped slot electroetched through said sheet and having the slot ends terminating at the lateral edges of said hinge tang.
21. An article of manufacture as defined in claim 19 characterized in that a plurality of said hinge tangs have substantially identical flexing characteristics and whereby substantially identical touch pressure applied to each by the tip of an operator's finger suffices to bring said plurality of electrical conductors associated with the depressed one of
22. An article of manufacture as defined in claim 27 characterized in that said shifting means includes electromechanical means controlled by flexing
Description:
BACKGROUND OF THE INVENTION
The present invention relates generally to electrical switches, but more especially to a multiple-switch construction in which closing a selected switch generates a unique signal comprising one or more electrical pulses by completing one or more electrically conductive contacts.
The use of computers and other mechanisms adapted to use intelligence based on binary codes has given rise to a need for equipment especially adapted to converting bits of intelligence into the electrical signals that are based upon binary codes. Of course the equipment generating the signals is not necessarily limited to such a use, as it may generate signals unrelated to binary coding systems or equipment. As an example, there is a need for equipment capable of generating electrical signals that correspond to English text, with the several punctuation marks, spacing of words and lines, and other machine functions that are normally found in typewriters and typesetting machines. It is customary to generate the necessary signals in terms of a binary code and either to use these signals immediately to actuate suitable apparatus, or to store the signals, as on magnetic tape, for a later use.
As typical of such a device, the present disclosure includes a coding device operated by a keyboard resembling a standard typewriter keyboard. It will be obvious that the construction for a coding device is independent of the ultimate use or destination of the signal generated by the coding device. Consequently, the present device may be regarded as a bank of switches that are individually controlled manually from a keyboard panel of suitable design. In a broader aspect of the invention, these signals may go to any type of device that responds to a particular combination of electrical pulses and the nature of the apparatus receiving the pulses is not limitative upon the present invention.
Thus, it is a general object of the present invention to provide a multiple-switch bank of novel construction for converting bits of intelligence into unique electrical signals, each signal comprising a plurality of electrical pulses.
It is also an object of the present invention to provide apparatus of novel construction in which a plurality of electrical switches can be arranged to be operated individually by a plurality of manually actuated keys arranged in a keyboard, one example of which is a keyboard resembling a standard typewriter.
It is a further object of the invention to provide a plurality of switches having a novel construction that permits the advantageous use of modern photoetching techniques.
It is also an object of the present invention to provide a multiple-switch bank which can be easily reprogrammed to a different code simply by exchanging one module of the switch bank.
SUMMARY OF THE INVENTION
The above, as well as other, objects of the present invention are achieved in apparatus for producing a unique group of electrical pulses for each of a plurality of individual bits of intelligence by providing a keyboard panel having a plurality of movable keys, there being one key for each such bit; and means responsive to deflection of a selected key of the keyboard to establish a unique pattern of electrically conductive contacts with a plurality of conductors, each of which contacts produces an electrical pulse in a conductor. The keyboard comprises a sheet of resilient material with a plurality of keys, each integral with the sheet at a resilient hinge permitting individual movement of the keys. Movement of a key deflects a movable element of the switch associated with the key, such movable element having a plurality of contacts which are movable into engagement with an equal plurality of fixed electrical conductors. The pattern of electrically conductive contacts at each switch is different and is established by a coating of insulating material on those conductors at which it is desired to avoid an electrically conductive contact. These fixed conductors typically are a plurality of parallel bars which pass beneath the keys of the keyboard.
BRIEF DESCRIPTION OF THE DRAWINGS
How the above, as well as other, objects and advantages of the present invention are achieved will be more readily understood by reference to the following description and to the annexed drawings, in which:
FIG. 1 is a plan view of a preferred form of apparatus embodying the present invention illustrating diagrammatically its connection to various examples of receiving or readout equipment.
FIG. 2 is an enlarged fragmentary vertical section taken on line 2--2 of FIG. 1.
FIG. 3 is an enlarged fragmentary plan, with portions of the keyboard panel and movable contact broken away, of the area indicated by the line 3--3 in FIG. 2.
FIG. 4 is a transverse section through the apparatus on line 4--4 of FIG. 2.
FIG. 5 is a plan view of the code block and the fixed contacts, removed from the apparatus to illustrate a preferred configuration of the code bars.
FIG. 6 is a further enlarged fragment in vertical section corresponding to the encircled area 6--6 in FIG. 4.
FIG. 7 is a fragmentary plan view of the code bars taken on line 7--7 of FIG. 6.
FIG. 8 is a fragmentary vertical section through the code block on line 8--8 of FIG. 6.
FIG. 9 is a fragmentary plan view, corresponding generally to FIG. 5, of a variational form of the invention.
FIG. 10 is a transverse vertical section through the modified form of the invention.
FIG. 11 is an enlarged fragmentary section corresponding to the portion of FIG. 10 encircled at 11--11.
DESCRIPTION OF A PREFERRED EMBODIMENT
Referring now to the drawing, and particularly to FIG. 1, there is shown in plan the complete coding switch bank indicated generally at 10. The apparatus is provided with a power supply terminal block 11 which may be connected by means of plug 12 and the attached cable to any suitable source of electric power, either direct current or alternating current, as may be desired. The apparatus is provided with output terminal block 14 which may be connected by plug 15 and conductor 16 to any one or more of a plurality of instruments capable of receiving and processing the coded electrical signals produced by apparatus 10.
Typical of such receiving devices, but in no way limitative thereto, is typewriter 17, telephone 18 with an acoustic pickup or coupler 18a, video receiver 19, and tape punch 20. Generally speaking, the encoding switch bank of the present invention may be incorporated into a system operated directly by the output signals from the encoding device or it may be connected to any suitable readout or storage unit, near or remote, capable of utilizing the output signals. The nature or purpose of such receiver unit is not limitative upon the present invention.
The encoding apparatus provides one or more electrical switches, each of which is capable of producing a unique combination of a plurality of electrical pulses. As may be seen from FIGS. 2 and 3, the apparatus comprises three major elements, keyboard panel 22 having a plurality of keys or manually operated switch actuators; movable contact assembly 24 providing a plurality of movable switch contacts, there being at least one movable contact for each key on panel 22; and code block or program plate 26 which has a plurality of encoding bars with which the movable contacts of assembly 24 are moved into engagement by individual keys of panel 22, all as will be further explained. Panel 22, assembly 24 and code block 26 are mounted in a frame 27 which holds these components in assembled position. The frame is preferably of an electrically nonconductive material to insulate the various electrical conductors, for obvious reasons.
Panel 22 is a generally flat, thin sheet of resilient material, preferably metal and typically stainless steel or other ferrous alloy. Selected areas of the panel have been treated in a manner to make them into individual keys, each key representing some predesignated bit of intelligence or information. In the illustrative example of the invention disclosed herein, the panel has been patterned after the standard typewriter keyboard, with the addition thereto of certain operational keys which designate functions rather than alphabetical characters. Thus keys 28 represent the usual alphabetical letters, both uppercase and lowercase, numerals, punctuation marks, and the like, normally found on the standard typewriter keyboard. In a location conventional with the standard typewriter, there is an elongated key 29 which represents the usual spacebar. Keys 30 perform the function of effecting a shift between upper and lowercase letters of the alphabet. Other functions normally accompanying typewriting text material may be allocated to keys 31 while additional keys 32 may be assigned special functions which are required only under certain circumstances or with the particular equipment to which the switch bank is connected.
As suggested by the variety of sizes and shapes shown in FIG. 1, the individual key portions of the panel 22 may be of any desired size and shape. In general, it is preferred that they be generally rectangular, having the same basic arrangement and location as keys on the standard typewriter keyboard for ease of operation by one familiar with the typewriter. Of course, this arrangement is for convenience in coding a language or bits of intelligence equivalent to test, and is not limitative upon the invention.
Each key of panel 22 is formed from a portion or area of the original sheet and is integral therewith. Each key is freed from the adjoining portions of the panel around the perimeter of the key except for a hinge portion at one side of the key. This construction is shown particularly in FIGS. 3 and 6. When each of the keys is generally of a quadrilateral shape, each key is discontinuous with the surrounding sheet along three sides at the gap 34, as indicated in FIGS. 3 and 6, between a key portion 28 and an adjoining portion of the panel 22. The key portion remains integral with the panel along the fourth side 35 by a hinge tang integral with and resiliently interconnecting the main body of panel 22 and key portion 35. The length of this hinge portion 35 can be controlled by the configuration given to the gap 34. As may be seen in FIGS. 1 and 3, gap 34 extends along a part of the fourth side of a key 28 to reduce the length of the hinge as compared with the corresponding dimension of the key.
This construction permits each key to be deflected downwardly by manual pressure on its upper face. This deflection of the key involves a swinging motion about its hinge 35, and the force required is reduced when the thickness of the sheet is reduced at the hinge line, or the length of the hinge is reduced, or both. The resilience of the hinge restores the key to the raised or neutral position when manual pressure is released.
It has been found that a photoetching process is a particularly effective and economical manner of making the individual keys in the panel. While any photoetching process may be used, this type of process generally involves making a film negative on which the keyboard layout is made with the necessary degree of accuracy. This layout is then transferred by a photographic process to the upper face of the panel, which previously has been covered with a photosensitive masking material. After exposure of the photosensitive material through the film negative, the masking material is washed away in those areas to be etched, in this case especially lines creating gap 34. The chemical etching process is then carried on to the extent that in the treated or etched areas metal is removed to a depth equal to substantially one-half the thickness of the panel sheet. This forms one-half of the gap 34. The sheet constituting panel 22 is preferably only a few thousandths of an inch thick, typically in the range of 10 to 20 thousandths of an inch and is particularly suited to forming keys of this character by a photoetching process as opposed to mechanical processes. By this first step of the process, each key is etched on one side of the sheet.
After this first etching step is completed, the etching process is repeated on the reverse or opposite side of the panel sheet in registration with the lines already etched. This second etching operation extends the gap 34 entirely through the panel sheet, thereby freeing each individual key from the adjoining sheet except along the hinge portion 35 between the spaced ends of etched gap 34. The final resulting structure is a panel having a plurality of individual keys which are resiliently hinged to the original panel sheet but are now capable of being deflected individually with respect to the plane of the sheet, such deflection taking place by bending the panel at the integral hinge 35, as indicated in FIG. 6.
Assembly 24 of movable switch contacts is disposed a short distance directly below panel 22. This contact assembly is likewise formed from a flat metal sheet which preferably is substantially coextensive in size and shape with panel 22. As shown in FIG. 3, contact assembly sheet 24 has a plurality of three-sided cutout areas 40, each of which defines a contact tab 41 that, like the keys in panel 22, is free of the remainder of the sheet around three sides and hinged to the sheet at the fourth side by an integral portion 42 of the sheet. The marginal portion of a tab 41 opposite hinge 42 is further subdivided to a comblike arrangement having a plurality of individual fingers 44. Each finger 44 is separated from the adjoining finger and remains integral with the tab 44 at its base. How the number of these fingers is arrived at will be explained later.
The cutout areas 40 and the slits between fingers 44 may be formed in any suitable manner, as by stamping, diecutting, or photoetching, as above described. Since the assembly 24 provides the movable contact of each of a plurality of electrical switches, a metal sheet is preferably used to form the movable contacts as well as to provide a common conductor connected to all the contacts. The switch assembly sheet 24 is connected to one conductor of power terminal 11 by any suitable means.
Interposed between top panel 22 and contact assembly 24 is guide plate 46 which is provided with a plurality of transversely extending bores in each of which is located a transfer pin 47 of a suitable electrically nonconductive material. There is one transfer pin for each key in panel 22, and the length of each pin is equal to the spacing between the underside of the key above it and a tab 41 below. Thus, each pin transfers from a key of the panel to the movable contact associated therewith, deflection of the key to actuate the associated switch elements. Guide 46 is a relatively thick, rigid sheet or plate which is interposed between keyboard panel 22 and the switch elements in order to give structural rigidity and stability to the apparatus. Guide plate 46 functions as a frame element as well as a support and guide for the transfer pins. It will be recalled that both sheets 22 and 24 are preferably thin flexible members and consequently when disposed horizontally, as indicated in the drawings, they are apt to sag when large enough to contain all keys of a typewriter keyboard. Guide sheets 46 not only separates these two sheets, but serves to give dimensional stability to the entire apparatus. Sheet 46 is preferably made of a suitable nonconductive material.
The bottom element of the encoding apparatus is code block or program plate 26. This block comprises a base 50 of any suitable insulating material on the top surface of which is located a plurality of code bars 52 which form the fixed contacts of each of the switches of the coding apparatus. It may be constructed by laminating a copper sheet to the base and chemically etching away unwanted parts of the sheet to leave on the base bars 52.
These code bars 52 are separate or discrete elements. They are arranged parallel to each other and are laterally spaced apart. While a separate row of code bars 52 can extend for the full length of each of the rows of keys on panel 22, it is preferable, when the keyboard comprises more than a single row of keys, that the code bars of all rows be interconnected. A series connection is effected when the code bars 52 are arranged as shown in FIG. 5. This zigzag pattern enables the code bars to extend in succession under all of the keys of the entire panel. The bars terminate at one edge of block 26 where they are connected individually to pins on terminal block 14, this terminal block being any suitable well-known type of pin connector, preferably mounted on base 50.
It is within the scope of the invention to provide any selected number of code bars 52. A minimum of one or two code bars may be sufficient with one to three keys. The keyboard panel 22 illustrated herein has a sufficient number of keys to permit formulation and transmission of English or other language text; and for this purpose an adequate number of combinations of pulses can be generated with eight code bars 52. In this illustrative case, six of the code bars are used in different combinations to generate enough unique groups of electrical pulses to transmit all of the letters of the alphabet, numerals, punctuation marks, and the like, necessary for English or other language text. Two additional bars are made available to transmit additional bits of intelligence that control machine operation rather than part of the message text. It thus becomes apparent that for any given installation, the number of code bars may be increased or decreased as required to generate the desired number of different groups of electrical pulses for the purpose intended.
In addition to the code bars 52, it is also desirable to add stop bars 53, one at each side of the group, which act to limit the downward travel of the movable switch contacts thereby safeguarding against transverse tilting or twisting of contact assembly 24 and the possibility of noncontact of one or more fingers with the associated code bar.
Because of this relationship, the tabs 41 are designed to have as many fingers 44 along one side as the total number of bars 52 and 53. Accordingly, each tab 41 is here provided with a total of 10 fingers, as many as seen in FIG. 6.
In operation, the operator manually depresses any selected key of panel 22. The operator's finger F is shown in phantom lines in FIG. 6. Manual pressure on the upper surface of the key 28 deflects the key downwardly, swinging it about the hinge at 35 to the position 28a of FIG. 6. This movement of key 28 is transmitted by transfer pin 47 to the associated tab 41, thereby bending the tab down and bringing the fingers 44 into contact with code bars 52. The two outside fingers 44 rest upon the inoperative stop bars 53 and serve to limit the downward travel of the movable contact assembly and more particularly to counteract any tendency of a group of contact fingers to tilt out of a plane parallel to the stationary contacts while moving into and out of engagement therewith since such tilt can result in the production of an erroneous pattern of signal bits. This movement of a tab 41 in response to deflection of the key of panel 22 produces a unique pattern of electrical contacts depending upon which of fingers 44 complete an electrical contact with code bars 52.
The pattern of electrical contacts is controlled by covering the top surface of each code bar 52 where no electrical contact is desired with a coating of an insulating material, as indicated at 55. This coating may be a piece of tape or a spray coating applied to the code bar, the insulating material being such as to prevent an electrical circuit being established between the two members 44 and 52 though mechanically engaged. Elsewhere, members 44 and 52 engage conductively and transfer electric current between tab 41 and code bars 52. Nonconducting coverings 55 are applied in such a manner that a different pattern of electrically conductive contacts between the fixed and movable switch contacts is established at each of the keys of keyboard 22 with the result that each key has its own unique pattern of electrical pulses established by depressing that key.
By way of further explanation, reference to FIGS. 6 and 7 indicates that the first, third and seventh code bars, counting from the left, are coated with nonconductive material 55. Consequently the electrical pulses are created by contacts in the second, fourth, fifth, sixth, and eighth bars, counting from the left. Thus, a group of five electrical impulses is generated, producing a unique electrical signal which is transmitted from the apparatus through output terminal 14 and cable 15.
In order to simulate more completely the operation of the standard typewriter keyboard, certain keys, such as keys 30, can be assigned a function of shifting from uppercase to lowercase letters of the alphabet. This case shift is effected physically in the coding apparatus by movement of code block 26 in a direction parallel to the longitudinal extent of code bars 52, thereby altering the pattern of electrical contacts made by each key and its associated tab 41.
To permit movement of code block 26, the block is preferably slidably mounted within frame 27 so that the code block is capable of limited linear movement to occupy any one of two or more selected operating positions. Mechanism for effecting this movement of the code block may be of any suitable type, but mechanism suitable for shifting the code block between two positions is illustrated in FIG. 2. It comprises solenoid 58 which is attached to frame 27. The solenoid has a longitudinally movable core 59 attached to bracket 60 which in turn is fastened to code block 26. When the solenoid is energized, plunger 59 is drawn into the solenoid coil, movement being toward the right in FIG. 2. This movement of the plunger is transmitted through bracket 60 to code block 26.
The result is to shift code block 26 in the direction and amount indicated by arrow 61 in FIG. 7. It will be seen that now the illustrated tab 41 can effect electrical contact with the first, third, fourth, fifth, seventh and eighth code bars 52, conductive contact with the second and sixth bars being prevented by the nonconductive areas 55. Thus, as a consequence of the physical shift in position of the code block, a change has been effected in the pattern of electrical contacts and a corresponding change has been made in the electrical pulses which are transmitted as a group through output terminal 14. After solenoid 58 is deenergized the code block is restored to its original position by force exerted by tension spring 62 which is fastened at one end to bracket 60 and is anchored at the other end to a stationary abutment on frame 27. The spring 62 continuously biases the code block towards a first position; then, when the code block has been moved to the right away from that position, returns it to its original position by movement to the left in FIG. 2.
It may be desired to shift the code block to a third operating position, and any suitable means may be provided. For example, a second solenoid with a different range of travel may be added.
Plate 50 is mounted in frame 27 for removal to permit easy replacement of the plate by another block with a different code. One advantage of this is that the same switch bank can thereby be programmed to transmit a different language or a different code for the same language or characters. For this reason, the entire code block, with terminal 14, preferably slides in and out of frame 27 through an open end thereof. In short, by interchanging code blocks, the switch bank can be reprogrammed for any purpose.
An electric circuit has not been shown since any suitable known circuit may be used in the switch bank. The use of very low voltages is contemplated; and it is preferred to use a single-point make-and-break type of circuit, of which several are well known, so that the fingers 44 and bars 52 are not energized when electrical contact is made or broken, thus contributing to a longer life and less maintenance for the apparatus.
VARIATIONAL EMBODIMENT OF THE INVENTION
There is shown in FIGS. 9, 10 and 11 simplified, variational embodiment of the invention. In this form, corresponding parts have been designated by the same reference numerals used above, but with the addition thereto of the letter a.
From FIGS. 9 and 11, it will be noted that the hinge structure of the keys 28, etc., on panel 22 has been modified, the resistance of the hinge to bending being controlled by reducing the thickness of the plate at the hinge rather than reducing the length of the hinge itself as in the embodiment first described. Thus, gap 34a is now U-shaped with its ends spaced further apart than in FIG. 3. In order to reduce the resistance of the key to bending, and to define more sharply the hinge point, a shallow groove 65 is etched at the location of the hinge at the spaced ends of gap 34a.
This variational form of the invention is also characterized by omission of guide plate 46 and loose pins 47 sliding in the guide plate to transmit to the tabs the movement of the keys of panel 22. Instead, each tab 41a is provided with a centrally located raised portion, typically in the form of button 66, against which a key 28a strikes when depressed, as shown in FIG. 11. This construction applies the operating force centrally to a tab 41a and causes the tab to bend about its hinge to bring its fingers 44a into engagement with code bars 52a. These code bars are arranged and constructed in the same fashion as already described and establish an electrical circuit through each conductive contact between the code bars and the fingers of the tab. It will be noted that the construction has also been simplified by the omission of stops 53.
As mentioned above, the invention is in no way limited by the number of keys in the top panel. Accordingly, in a coding device in which only a relatively small number of keys is required, the area of panel 22 and the sheets beneath it is so reduced that the presence of an intermediate guide plate 46 is not required. Under these circumstances, the simplified form disclosed in FIGS. 9, 10 and 11 may be entirely satisfactory.
In summary, it is to be understood that the electrical signals constituting the output at terminal block 14 are composed of unique arrangements of electrical pulses. The number of possible combinations depends upon the number of code bars. When eight code bars are used as in the preferred embodiment described above, each signal may contain anywhere from one to eight electrical pulses distributed in any desired manner over one or more of the available code bars and output terminals connected thereto.
A compatible receiver is designed to differentiate between pulses on different code bars so that even a single pulse represents a different bit of information depending upon which of the code bars generates that particular signal. The duration or electrical characteristics of the signal may or may not be of any consequence to the receiver. Thus, the receiver may or may not differentiate between alternating current and direct current signals; but it is assumed in this disclosure that the mere existence of an electrical pulse from a code bar is sufficient to form an intelligible signal at the output terminal. From the foregoing it will be appreciated that this coding apparatus is particularly suited for generating electrical signals in which the pulses represent a binary code. Accordingly, apparatus adapted to receive signals in a binary code is compatible with the coding or programming device of the present invention.
From the foregoing discussion it will be apparent that various changes in the details and design or arrangement of the elements of the coding apparatus may occur to persons skilled in the art without departing from the spirit and scope of the present invention. Accordingly, it is to be understood that the foregoing description is considered to be illustrative of, rather than limitative upon, the scope of the present invention.
The present invention relates generally to electrical switches, but more especially to a multiple-switch construction in which closing a selected switch generates a unique signal comprising one or more electrical pulses by completing one or more electrically conductive contacts.
The use of computers and other mechanisms adapted to use intelligence based on binary codes has given rise to a need for equipment especially adapted to converting bits of intelligence into the electrical signals that are based upon binary codes. Of course the equipment generating the signals is not necessarily limited to such a use, as it may generate signals unrelated to binary coding systems or equipment. As an example, there is a need for equipment capable of generating electrical signals that correspond to English text, with the several punctuation marks, spacing of words and lines, and other machine functions that are normally found in typewriters and typesetting machines. It is customary to generate the necessary signals in terms of a binary code and either to use these signals immediately to actuate suitable apparatus, or to store the signals, as on magnetic tape, for a later use.
As typical of such a device, the present disclosure includes a coding device operated by a keyboard resembling a standard typewriter keyboard. It will be obvious that the construction for a coding device is independent of the ultimate use or destination of the signal generated by the coding device. Consequently, the present device may be regarded as a bank of switches that are individually controlled manually from a keyboard panel of suitable design. In a broader aspect of the invention, these signals may go to any type of device that responds to a particular combination of electrical pulses and the nature of the apparatus receiving the pulses is not limitative upon the present invention.
Thus, it is a general object of the present invention to provide a multiple-switch bank of novel construction for converting bits of intelligence into unique electrical signals, each signal comprising a plurality of electrical pulses.
It is also an object of the present invention to provide apparatus of novel construction in which a plurality of electrical switches can be arranged to be operated individually by a plurality of manually actuated keys arranged in a keyboard, one example of which is a keyboard resembling a standard typewriter.
It is a further object of the invention to provide a plurality of switches having a novel construction that permits the advantageous use of modern photoetching techniques.
It is also an object of the present invention to provide a multiple-switch bank which can be easily reprogrammed to a different code simply by exchanging one module of the switch bank.
SUMMARY OF THE INVENTION
The above, as well as other, objects of the present invention are achieved in apparatus for producing a unique group of electrical pulses for each of a plurality of individual bits of intelligence by providing a keyboard panel having a plurality of movable keys, there being one key for each such bit; and means responsive to deflection of a selected key of the keyboard to establish a unique pattern of electrically conductive contacts with a plurality of conductors, each of which contacts produces an electrical pulse in a conductor. The keyboard comprises a sheet of resilient material with a plurality of keys, each integral with the sheet at a resilient hinge permitting individual movement of the keys. Movement of a key deflects a movable element of the switch associated with the key, such movable element having a plurality of contacts which are movable into engagement with an equal plurality of fixed electrical conductors. The pattern of electrically conductive contacts at each switch is different and is established by a coating of insulating material on those conductors at which it is desired to avoid an electrically conductive contact. These fixed conductors typically are a plurality of parallel bars which pass beneath the keys of the keyboard.
BRIEF DESCRIPTION OF THE DRAWINGS
How the above, as well as other, objects and advantages of the present invention are achieved will be more readily understood by reference to the following description and to the annexed drawings, in which:
FIG. 1 is a plan view of a preferred form of apparatus embodying the present invention illustrating diagrammatically its connection to various examples of receiving or readout equipment.
FIG. 2 is an enlarged fragmentary vertical section taken on line 2--2 of FIG. 1.
FIG. 3 is an enlarged fragmentary plan, with portions of the keyboard panel and movable contact broken away, of the area indicated by the line 3--3 in FIG. 2.
FIG. 4 is a transverse section through the apparatus on line 4--4 of FIG. 2.
FIG. 5 is a plan view of the code block and the fixed contacts, removed from the apparatus to illustrate a preferred configuration of the code bars.
FIG. 6 is a further enlarged fragment in vertical section corresponding to the encircled area 6--6 in FIG. 4.
FIG. 7 is a fragmentary plan view of the code bars taken on line 7--7 of FIG. 6.
FIG. 8 is a fragmentary vertical section through the code block on line 8--8 of FIG. 6.
FIG. 9 is a fragmentary plan view, corresponding generally to FIG. 5, of a variational form of the invention.
FIG. 10 is a transverse vertical section through the modified form of the invention.
FIG. 11 is an enlarged fragmentary section corresponding to the portion of FIG. 10 encircled at 11--11.
DESCRIPTION OF A PREFERRED EMBODIMENT
Referring now to the drawing, and particularly to FIG. 1, there is shown in plan the complete coding switch bank indicated generally at 10. The apparatus is provided with a power supply terminal block 11 which may be connected by means of plug 12 and the attached cable to any suitable source of electric power, either direct current or alternating current, as may be desired. The apparatus is provided with output terminal block 14 which may be connected by plug 15 and conductor 16 to any one or more of a plurality of instruments capable of receiving and processing the coded electrical signals produced by apparatus 10.
Typical of such receiving devices, but in no way limitative thereto, is typewriter 17, telephone 18 with an acoustic pickup or coupler 18a, video receiver 19, and tape punch 20. Generally speaking, the encoding switch bank of the present invention may be incorporated into a system operated directly by the output signals from the encoding device or it may be connected to any suitable readout or storage unit, near or remote, capable of utilizing the output signals. The nature or purpose of such receiver unit is not limitative upon the present invention.
The encoding apparatus provides one or more electrical switches, each of which is capable of producing a unique combination of a plurality of electrical pulses. As may be seen from FIGS. 2 and 3, the apparatus comprises three major elements, keyboard panel 22 having a plurality of keys or manually operated switch actuators; movable contact assembly 24 providing a plurality of movable switch contacts, there being at least one movable contact for each key on panel 22; and code block or program plate 26 which has a plurality of encoding bars with which the movable contacts of assembly 24 are moved into engagement by individual keys of panel 22, all as will be further explained. Panel 22, assembly 24 and code block 26 are mounted in a frame 27 which holds these components in assembled position. The frame is preferably of an electrically nonconductive material to insulate the various electrical conductors, for obvious reasons.
Panel 22 is a generally flat, thin sheet of resilient material, preferably metal and typically stainless steel or other ferrous alloy. Selected areas of the panel have been treated in a manner to make them into individual keys, each key representing some predesignated bit of intelligence or information. In the illustrative example of the invention disclosed herein, the panel has been patterned after the standard typewriter keyboard, with the addition thereto of certain operational keys which designate functions rather than alphabetical characters. Thus keys 28 represent the usual alphabetical letters, both uppercase and lowercase, numerals, punctuation marks, and the like, normally found on the standard typewriter keyboard. In a location conventional with the standard typewriter, there is an elongated key 29 which represents the usual spacebar. Keys 30 perform the function of effecting a shift between upper and lowercase letters of the alphabet. Other functions normally accompanying typewriting text material may be allocated to keys 31 while additional keys 32 may be assigned special functions which are required only under certain circumstances or with the particular equipment to which the switch bank is connected.
As suggested by the variety of sizes and shapes shown in FIG. 1, the individual key portions of the panel 22 may be of any desired size and shape. In general, it is preferred that they be generally rectangular, having the same basic arrangement and location as keys on the standard typewriter keyboard for ease of operation by one familiar with the typewriter. Of course, this arrangement is for convenience in coding a language or bits of intelligence equivalent to test, and is not limitative upon the invention.
Each key of panel 22 is formed from a portion or area of the original sheet and is integral therewith. Each key is freed from the adjoining portions of the panel around the perimeter of the key except for a hinge portion at one side of the key. This construction is shown particularly in FIGS. 3 and 6. When each of the keys is generally of a quadrilateral shape, each key is discontinuous with the surrounding sheet along three sides at the gap 34, as indicated in FIGS. 3 and 6, between a key portion 28 and an adjoining portion of the panel 22. The key portion remains integral with the panel along the fourth side 35 by a hinge tang integral with and resiliently interconnecting the main body of panel 22 and key portion 35. The length of this hinge portion 35 can be controlled by the configuration given to the gap 34. As may be seen in FIGS. 1 and 3, gap 34 extends along a part of the fourth side of a key 28 to reduce the length of the hinge as compared with the corresponding dimension of the key.
This construction permits each key to be deflected downwardly by manual pressure on its upper face. This deflection of the key involves a swinging motion about its hinge 35, and the force required is reduced when the thickness of the sheet is reduced at the hinge line, or the length of the hinge is reduced, or both. The resilience of the hinge restores the key to the raised or neutral position when manual pressure is released.
It has been found that a photoetching process is a particularly effective and economical manner of making the individual keys in the panel. While any photoetching process may be used, this type of process generally involves making a film negative on which the keyboard layout is made with the necessary degree of accuracy. This layout is then transferred by a photographic process to the upper face of the panel, which previously has been covered with a photosensitive masking material. After exposure of the photosensitive material through the film negative, the masking material is washed away in those areas to be etched, in this case especially lines creating gap 34. The chemical etching process is then carried on to the extent that in the treated or etched areas metal is removed to a depth equal to substantially one-half the thickness of the panel sheet. This forms one-half of the gap 34. The sheet constituting panel 22 is preferably only a few thousandths of an inch thick, typically in the range of 10 to 20 thousandths of an inch and is particularly suited to forming keys of this character by a photoetching process as opposed to mechanical processes. By this first step of the process, each key is etched on one side of the sheet.
After this first etching step is completed, the etching process is repeated on the reverse or opposite side of the panel sheet in registration with the lines already etched. This second etching operation extends the gap 34 entirely through the panel sheet, thereby freeing each individual key from the adjoining sheet except along the hinge portion 35 between the spaced ends of etched gap 34. The final resulting structure is a panel having a plurality of individual keys which are resiliently hinged to the original panel sheet but are now capable of being deflected individually with respect to the plane of the sheet, such deflection taking place by bending the panel at the integral hinge 35, as indicated in FIG. 6.
Assembly 24 of movable switch contacts is disposed a short distance directly below panel 22. This contact assembly is likewise formed from a flat metal sheet which preferably is substantially coextensive in size and shape with panel 22. As shown in FIG. 3, contact assembly sheet 24 has a plurality of three-sided cutout areas 40, each of which defines a contact tab 41 that, like the keys in panel 22, is free of the remainder of the sheet around three sides and hinged to the sheet at the fourth side by an integral portion 42 of the sheet. The marginal portion of a tab 41 opposite hinge 42 is further subdivided to a comblike arrangement having a plurality of individual fingers 44. Each finger 44 is separated from the adjoining finger and remains integral with the tab 44 at its base. How the number of these fingers is arrived at will be explained later.
The cutout areas 40 and the slits between fingers 44 may be formed in any suitable manner, as by stamping, diecutting, or photoetching, as above described. Since the assembly 24 provides the movable contact of each of a plurality of electrical switches, a metal sheet is preferably used to form the movable contacts as well as to provide a common conductor connected to all the contacts. The switch assembly sheet 24 is connected to one conductor of power terminal 11 by any suitable means.
Interposed between top panel 22 and contact assembly 24 is guide plate 46 which is provided with a plurality of transversely extending bores in each of which is located a transfer pin 47 of a suitable electrically nonconductive material. There is one transfer pin for each key in panel 22, and the length of each pin is equal to the spacing between the underside of the key above it and a tab 41 below. Thus, each pin transfers from a key of the panel to the movable contact associated therewith, deflection of the key to actuate the associated switch elements. Guide 46 is a relatively thick, rigid sheet or plate which is interposed between keyboard panel 22 and the switch elements in order to give structural rigidity and stability to the apparatus. Guide plate 46 functions as a frame element as well as a support and guide for the transfer pins. It will be recalled that both sheets 22 and 24 are preferably thin flexible members and consequently when disposed horizontally, as indicated in the drawings, they are apt to sag when large enough to contain all keys of a typewriter keyboard. Guide sheets 46 not only separates these two sheets, but serves to give dimensional stability to the entire apparatus. Sheet 46 is preferably made of a suitable nonconductive material.
The bottom element of the encoding apparatus is code block or program plate 26. This block comprises a base 50 of any suitable insulating material on the top surface of which is located a plurality of code bars 52 which form the fixed contacts of each of the switches of the coding apparatus. It may be constructed by laminating a copper sheet to the base and chemically etching away unwanted parts of the sheet to leave on the base bars 52.
These code bars 52 are separate or discrete elements. They are arranged parallel to each other and are laterally spaced apart. While a separate row of code bars 52 can extend for the full length of each of the rows of keys on panel 22, it is preferable, when the keyboard comprises more than a single row of keys, that the code bars of all rows be interconnected. A series connection is effected when the code bars 52 are arranged as shown in FIG. 5. This zigzag pattern enables the code bars to extend in succession under all of the keys of the entire panel. The bars terminate at one edge of block 26 where they are connected individually to pins on terminal block 14, this terminal block being any suitable well-known type of pin connector, preferably mounted on base 50.
It is within the scope of the invention to provide any selected number of code bars 52. A minimum of one or two code bars may be sufficient with one to three keys. The keyboard panel 22 illustrated herein has a sufficient number of keys to permit formulation and transmission of English or other language text; and for this purpose an adequate number of combinations of pulses can be generated with eight code bars 52. In this illustrative case, six of the code bars are used in different combinations to generate enough unique groups of electrical pulses to transmit all of the letters of the alphabet, numerals, punctuation marks, and the like, necessary for English or other language text. Two additional bars are made available to transmit additional bits of intelligence that control machine operation rather than part of the message text. It thus becomes apparent that for any given installation, the number of code bars may be increased or decreased as required to generate the desired number of different groups of electrical pulses for the purpose intended.
In addition to the code bars 52, it is also desirable to add stop bars 53, one at each side of the group, which act to limit the downward travel of the movable switch contacts thereby safeguarding against transverse tilting or twisting of contact assembly 24 and the possibility of noncontact of one or more fingers with the associated code bar.
Because of this relationship, the tabs 41 are designed to have as many fingers 44 along one side as the total number of bars 52 and 53. Accordingly, each tab 41 is here provided with a total of 10 fingers, as many as seen in FIG. 6.
In operation, the operator manually depresses any selected key of panel 22. The operator's finger F is shown in phantom lines in FIG. 6. Manual pressure on the upper surface of the key 28 deflects the key downwardly, swinging it about the hinge at 35 to the position 28a of FIG. 6. This movement of key 28 is transmitted by transfer pin 47 to the associated tab 41, thereby bending the tab down and bringing the fingers 44 into contact with code bars 52. The two outside fingers 44 rest upon the inoperative stop bars 53 and serve to limit the downward travel of the movable contact assembly and more particularly to counteract any tendency of a group of contact fingers to tilt out of a plane parallel to the stationary contacts while moving into and out of engagement therewith since such tilt can result in the production of an erroneous pattern of signal bits. This movement of a tab 41 in response to deflection of the key of panel 22 produces a unique pattern of electrical contacts depending upon which of fingers 44 complete an electrical contact with code bars 52.
The pattern of electrical contacts is controlled by covering the top surface of each code bar 52 where no electrical contact is desired with a coating of an insulating material, as indicated at 55. This coating may be a piece of tape or a spray coating applied to the code bar, the insulating material being such as to prevent an electrical circuit being established between the two members 44 and 52 though mechanically engaged. Elsewhere, members 44 and 52 engage conductively and transfer electric current between tab 41 and code bars 52. Nonconducting coverings 55 are applied in such a manner that a different pattern of electrically conductive contacts between the fixed and movable switch contacts is established at each of the keys of keyboard 22 with the result that each key has its own unique pattern of electrical pulses established by depressing that key.
By way of further explanation, reference to FIGS. 6 and 7 indicates that the first, third and seventh code bars, counting from the left, are coated with nonconductive material 55. Consequently the electrical pulses are created by contacts in the second, fourth, fifth, sixth, and eighth bars, counting from the left. Thus, a group of five electrical impulses is generated, producing a unique electrical signal which is transmitted from the apparatus through output terminal 14 and cable 15.
In order to simulate more completely the operation of the standard typewriter keyboard, certain keys, such as keys 30, can be assigned a function of shifting from uppercase to lowercase letters of the alphabet. This case shift is effected physically in the coding apparatus by movement of code block 26 in a direction parallel to the longitudinal extent of code bars 52, thereby altering the pattern of electrical contacts made by each key and its associated tab 41.
To permit movement of code block 26, the block is preferably slidably mounted within frame 27 so that the code block is capable of limited linear movement to occupy any one of two or more selected operating positions. Mechanism for effecting this movement of the code block may be of any suitable type, but mechanism suitable for shifting the code block between two positions is illustrated in FIG. 2. It comprises solenoid 58 which is attached to frame 27. The solenoid has a longitudinally movable core 59 attached to bracket 60 which in turn is fastened to code block 26. When the solenoid is energized, plunger 59 is drawn into the solenoid coil, movement being toward the right in FIG. 2. This movement of the plunger is transmitted through bracket 60 to code block 26.
The result is to shift code block 26 in the direction and amount indicated by arrow 61 in FIG. 7. It will be seen that now the illustrated tab 41 can effect electrical contact with the first, third, fourth, fifth, seventh and eighth code bars 52, conductive contact with the second and sixth bars being prevented by the nonconductive areas 55. Thus, as a consequence of the physical shift in position of the code block, a change has been effected in the pattern of electrical contacts and a corresponding change has been made in the electrical pulses which are transmitted as a group through output terminal 14. After solenoid 58 is deenergized the code block is restored to its original position by force exerted by tension spring 62 which is fastened at one end to bracket 60 and is anchored at the other end to a stationary abutment on frame 27. The spring 62 continuously biases the code block towards a first position; then, when the code block has been moved to the right away from that position, returns it to its original position by movement to the left in FIG. 2.
It may be desired to shift the code block to a third operating position, and any suitable means may be provided. For example, a second solenoid with a different range of travel may be added.
Plate 50 is mounted in frame 27 for removal to permit easy replacement of the plate by another block with a different code. One advantage of this is that the same switch bank can thereby be programmed to transmit a different language or a different code for the same language or characters. For this reason, the entire code block, with terminal 14, preferably slides in and out of frame 27 through an open end thereof. In short, by interchanging code blocks, the switch bank can be reprogrammed for any purpose.
An electric circuit has not been shown since any suitable known circuit may be used in the switch bank. The use of very low voltages is contemplated; and it is preferred to use a single-point make-and-break type of circuit, of which several are well known, so that the fingers 44 and bars 52 are not energized when electrical contact is made or broken, thus contributing to a longer life and less maintenance for the apparatus.
VARIATIONAL EMBODIMENT OF THE INVENTION
There is shown in FIGS. 9, 10 and 11 simplified, variational embodiment of the invention. In this form, corresponding parts have been designated by the same reference numerals used above, but with the addition thereto of the letter a.
From FIGS. 9 and 11, it will be noted that the hinge structure of the keys 28, etc., on panel 22 has been modified, the resistance of the hinge to bending being controlled by reducing the thickness of the plate at the hinge rather than reducing the length of the hinge itself as in the embodiment first described. Thus, gap 34a is now U-shaped with its ends spaced further apart than in FIG. 3. In order to reduce the resistance of the key to bending, and to define more sharply the hinge point, a shallow groove 65 is etched at the location of the hinge at the spaced ends of gap 34a.
This variational form of the invention is also characterized by omission of guide plate 46 and loose pins 47 sliding in the guide plate to transmit to the tabs the movement of the keys of panel 22. Instead, each tab 41a is provided with a centrally located raised portion, typically in the form of button 66, against which a key 28a strikes when depressed, as shown in FIG. 11. This construction applies the operating force centrally to a tab 41a and causes the tab to bend about its hinge to bring its fingers 44a into engagement with code bars 52a. These code bars are arranged and constructed in the same fashion as already described and establish an electrical circuit through each conductive contact between the code bars and the fingers of the tab. It will be noted that the construction has also been simplified by the omission of stops 53.
As mentioned above, the invention is in no way limited by the number of keys in the top panel. Accordingly, in a coding device in which only a relatively small number of keys is required, the area of panel 22 and the sheets beneath it is so reduced that the presence of an intermediate guide plate 46 is not required. Under these circumstances, the simplified form disclosed in FIGS. 9, 10 and 11 may be entirely satisfactory.
In summary, it is to be understood that the electrical signals constituting the output at terminal block 14 are composed of unique arrangements of electrical pulses. The number of possible combinations depends upon the number of code bars. When eight code bars are used as in the preferred embodiment described above, each signal may contain anywhere from one to eight electrical pulses distributed in any desired manner over one or more of the available code bars and output terminals connected thereto.
A compatible receiver is designed to differentiate between pulses on different code bars so that even a single pulse represents a different bit of information depending upon which of the code bars generates that particular signal. The duration or electrical characteristics of the signal may or may not be of any consequence to the receiver. Thus, the receiver may or may not differentiate between alternating current and direct current signals; but it is assumed in this disclosure that the mere existence of an electrical pulse from a code bar is sufficient to form an intelligible signal at the output terminal. From the foregoing it will be appreciated that this coding apparatus is particularly suited for generating electrical signals in which the pulses represent a binary code. Accordingly, apparatus adapted to receive signals in a binary code is compatible with the coding or programming device of the present invention.
From the foregoing discussion it will be apparent that various changes in the details and design or arrangement of the elements of the coding apparatus may occur to persons skilled in the art without departing from the spirit and scope of the present invention. Accordingly, it is to be understood that the foregoing description is considered to be illustrative of, rather than limitative upon, the scope of the present invention.