United States Patent 3648817

The present invention is directed to the improved mounting and disposition of a series of magnetic switching members utilized to convert the characters printed on a keyboard into coded electrical signals, generally wherein each switch is opened or closed in response to movement of each of a selected group of interposers which control printing of each character on the keyboard. Each of the magnetic switch elements is mounted on the back of a circuit board, and a magnetic switch-actuating member for each switch is releasably inserted in the slotted end of a holder which in turn is attached in close-fitting relation to an interposer so that the actuating member is securely but adjustably disposed for movement in response to movement of its interposer in closely spaced parallel relation to a switch.

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International Classes:
B41J3/50; (IPC1-7): B41J5/30
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Primary Examiner:
Burr, Edgar S.
What is claimed is

1. In a code generating keyboard system, a magnetic switch assembly for converting translational movement of an elongated link arm to an electrical signal comprising:

2. In a code generating keyboard system according to claim 1, said magnet aligned in closed spaced parallel relation to said switch member, the polarity of the magnet being such as to close said switch element as the magnet is advanced parallel to said switch element in response to movement of the link arm.

3. In a code generating keyboard system according to claim 1 the link arm-receiving recessed portion frictionally engaging the link arm and being slidable lengthwise of the link arm to align said magnet in the magnet-receiving slot in said magnet holder opposite to the switch member, and said magnet being slidable in the magnet-receiving slot in a direction parallel to the length of the link arm independently of slidable adjustment of said holder lengthwise of the link arm.

4. In a code generating keyboard unit having a plurality of interposers aligned in side-by-side relation to one another for lengthwise, independent movement of selected ones of said interposers between an inactive position and an active position according to a preselected code in advancing characters on the keyboard to a printing position, the combination therewith comprising:

5. In a code generating keyboard unit according to claim 4, said clamping side portions having opposed, facing magnet-receiving grooves therein, the width of the slot defined by said clamping side portions being such that said magnet will spread the side portions as it is inserted into alignment with the grooves so as to be securely held within the grooves under the natural tension of the side portions of the slot.

6. In a code generating keyboard unit wherein a printing mechanism is actuated by control linkage in response to depression of one of a plurality of key levers, each key lever representative of a different character to advance a print element corresponding to that character into position, the combination therewith comprising:

This invention relates to coding devices for business machines, and more particularly relates to a novel and improved means for converting information as it is typed or printed into coded electrical signals for transmission to a recording unit.

It is customary to convert information as it is printed or typed by a business machine, such as, a keyboard printer unit, into coded electrical signals and signal combinations representative of each item of information printed, recording and signals produced, and thereafter transmitting the signal back to the typewriter for automatically printing the same matter as originally prepared, the objective being of course to provide high speed, reliable reproduction of the information. A typical keyboard printer unit is that generally disclosed and set forth in U.S. Pat. No. 2,919,002 to L. E. Palmer or U.S. Pat. No. 3,260,340 to H. C. Locklar et al., wherein the printer unit is provided with a spherical print head bearing columns and rows of characters, each character being selectively advanced into position for printing by rotation and tilt of the print head in response to actuation of a key lever. The rotation and tilt of the print head are mechanically controlled by a displacement mechanism which is actuated by linkage set in motion by depression of each key lever. The linkage broadly comprises a character interposer movable in response to depression of each key lever to actuate one or more selector bails and latch interposers in predetermined combinations representative of the key or character and which, through a series of selector latches in the displacement mechanism will determine the degree of rotation and tilt of the print head. Thereafter the head is advanced to strike the platen to print the chosen character.

In a similar manner, series of electrical pulses or signals representing each character or item of information may be transmitted back from a remote station, such as, a magnetic tape recording and playback unit to a series of electromagnets or solenoids associated with the latch interposers. Each signal of a combination representing a character will energize a solenoid and, through the latch interposers, will control rotation and tilt of the print head to present the chosen character for printing.

In converting the information into coded electrical signals for recording or other purposes, it is highly desirable to provide an arrangement which is compact, can be quickly and easily installed and is readily conformable and adjustable for use in different types of business machines. In accordance with the present invention, a magnetic switch assembly has been devised which will accomplish the foregoing and in a unique manner will closely and accurately follow movement of the control linkage actuated for printing each character to generate a combination of electrical pulses or signals representative of each character or unit of information.

It is therefore an object of the present invention to provide a novel and improved coding device particularly adaptable for converting characters as they are printed or typed into electrical signals for transmission to another recording unit; and further to provide a device of the character described which is compact and comprises a minimum number of parts so as to permit its mounting and disposition directly between the control linkage and the control circuitry of the printer unit.

It is another object of the present invention to provide a magnetic switch assembly for coding information printed by means of a keyboard printer unit wherein the assembly is readily attachable to and detachable from the printer control linkage and a circuit mounting board so as to be readily conformable for use with different types of typewriter printer units, and can be easily adjusted and serviced once in place; and more specifically to provide a magnetic switch assembly in which a series of switching elements are selectively controlled by a corresponding number of magnetic actuating members adjustably insertable in holders attached to the control linkage to produce coded electrical signals in different combinations representative of each character printed.

It is a still further object of the present invention to provide for a novel and improved magnetic switch assembly wherein reed switch elements are positioned on the back of the printed circuit board, each element to be actuated in direct response to movement of a magnetic actuating member releasably inserted in a holder to follow movement of control linkage members in a printer unit for producing electrical signals or pulses for transmission in combinations representative of each character manually selected for printing.

In the magnetic switch assembly of the present invention, each of a series of magnetically responsive switch elements is mounted on the back of a circuit board in facing relation to each latch interposer or equivalent linkage arm in the keyboard unit which controls movement of the print element. A magnetic actuating member for each of the switch elements is releasably inserted laterally in the forwardly divergent slotted end of a holder projecting from each of the latch interposers toward an aligned switch element. Each holder is connected to an interposer by snap-fitting insertion of the interposer into a recess at the end of the holder opposite to the slotted end. The actuating member is positively held against lateral release but is axially adjustable in the slotted end with the sides of the slotted end flanking the sides of the switch element; and upon movement of the interposer the actuating member will axially advance in closely spaced parallel relation to the switch either to effect opening or closing of the switch. In this way, a selected combination of switches will be actuated when a corresponding combination of interposers is advanced to print a particular character and which actuation may be utilized to generate coded electrical signals for transmission to another station.

The above and other objects, advantages and features of the present invention will become more readily appreciated and understood from a consideration of the following detailed description when taken together with the accompanying drawings, in which:

FIG. 1 is a perspective view illustrating parts of a conventional keyboard printer unit.

FIG. 2 is a perspective view from the underside of the printer unit shown in FIG. 1 illustrating the relative disposition and arrangement of a preferred form of magnetic switch assembly.

FIG. 3 is an elevational view of a series of switching elements mounted on a printed circuit board.

FIG. 4 is a top view in detail of the preferred form of one of the magnetic switches in the switch assembly in accordance with the present invention; and

FIG. 5 is a sectional view taken about line 5--5 of FIG. 4.

Referring in detail to the drawings, in FIG. 1 a conventional printer unit has a spherical print head 10 provided with rows and columns of characters, not shown, to be selectively advanced into position for printing by means of a displacement mechanism which is actuated in response to depression of each of a plurality of key levers, one such key lever being designated at 12 for movement about a shaft 13. Whenever a key lever 12 is depressed by its key button 15, a pawl 16 on key lever 12 engages a character interposer 17 to slidably advance the interposer and in turn to cause movement of selector bails 20, the latter being disposed for engagement by lugs 21 on the character interposer. Each character interposer has a different lug spacing so that different combinations of selector bails are advanced in response to depression of each key lever; and each combination of any one or more of the selector bails so advanced by a key lever is representative of the character displayed on the related key button. Each of the selector bails will control movement of an associated latch interposer 24, and of the latch interposers shown in FIGS. 1 and 2 it will be noted that each has a pivotal rod 25 to control movement of a selector latch, designated L, out of the path of a common actuating bail 26. Each latch interposer is normally urged in a rearward direction by a spring 25', and each selector latch is biased rearwardly into the path of the bail 26 by a spring 27. The actuating bail 26 is caused to be moved downwardly against those selector latches L not removed from its path by the latch interposers 24, and those latches engaged will operate through the displacement mechanism to advance the desired character, corresponding to the key lever depressed, into position for printing.

In order to correlate advancement of the actuating bail 26 with movement of the selector latches, each character interposer has a special lug 28 which when depressed will strike a cycle bail 29 forcing the bail 29 to move downwardly and, through suitable control linkage represented at 30, actuate a clutch member 32 for rotation of a cycle shaft 34 by motor drive 35. In each print cycle, the cycle shaft will rotate 180° and through gearing 36, 37 and 38 is operative to rotate a filter shaft 40 through 180°. The filter shaft 40 has diametrically opposed blades 41 positioned beneath the character interposer so that in each 180° print cycle a blade on the filter shaft is engageable with the shoulder 42 on the character interposer to advance the latter in a direction to engage and move one or more of the selector bails in the manner previously described.

As broadly illustrated in FIG. 2, the actuating bail 26 includes a pivotal frame 43 having rollers 44 on either side which are biased upwardly by a spring 45 into contact with cycle shaft cams, not shown, on the cycle shaft. As the cycle shaft is rotated through each print cycle the cams will engage the rollers 44 to force the bail to pivot downwardly about its shaft causing displacement of those selector latches not moved out of position to actuate the displacement mechanism. Of course other parts and elements are associated with the character selection unit described to insure proper correlation between the selector latches, actuating bail, cycle shaft and filter shaft in the printing of each character, it being understood that the foregoing description of a typical keyboard printer unit is intended more as a setting for the following description of a preferred form of magnetic switch assembly.

As shown in FIGS. 2 to 5, the magnetic switch assembly 50 of the present invention comprises a plurality of magnetic actuating members 52, each extending downwardly from connection to a latch interposer 24, and a corresponding number of reed switches 54 are mounted on the back of a printed circuit board 55 in alignment with the magnetic actuating members. Broadly, each actuating member will follow forward advancement of its latch interposer in response to depression of a key lever to close the associated reed switch and to cause a signal to be transmitted through suitable logical circuitry on the printed circuit board to a recording unit, not shown. Although forming no part of the present invention, a filter switch 56 mounted at the end of the filter shaft 40 is operative to control the period of energization of a series of solenoids 58 in automatically printing characters played back from the recording unit, all in a manner described in copending application for "Keyboard Printer Character Selection Unit," filed Jan. 21, 1969, Ser. No. 792,471. The filter switch may also be connected through a clock circuit, not shown, to a suitable logic control circuit on the printed circuit board 55 to synchronize the transmittal of each combination of pulses representing a character in response to actuation of the reed switches 54.

It is important to note that the reed switches 54 can be mounted on one face of the printed circuit board opposite to the logic circuit elements for the keyboard printer unit so as to be in the direct path of movement of the magnetic actuating members 52. As shown in detail in FIGS. 4 and 5, each reed switch conventionally comprises a glass envelope or cartridge 60 containing reed elements 61 and 62, and terminal leads 63 and 64 extend from opposite ends of the cartridge for connection to the board. Of course, various different types of reed switches are commercially available, and as such the reed switch 54 forms no part of the present invention. For the purpose of illustration, however, the reed elements 61 and 62 may extend inwardly from opposite ends of the cartridge and be normally biased to an open or separated position. The reeds are suitably composed of a magnetizable material so that when the inner free ends of the reeds are brought under the influence of a magnetic field the free ends will be drawn together to close the switch and form a path for transmission of a pulse from suitable pulse generating means in the logic circuit through the recording unit. Again, different forms of reed switches may be employed which in response to movement of a magnetic actuating member into predetermined relation to the inner ends of the reed elements will activate the pulse generating circuit for transmission of pulses to the recording unit, the important feature of the present invention residing more in the mounting and relative disposition of the reed switch and magnetic actuating members.

In order to support each magnetic actuating member in predetermined relation to its respective switch, a holder 70 is formed of a relatively thin flat strip composed of electrically nonconductive or nonmagnetic material possessing limited resiliency or flexibility, such as, a plastic or hard rubber or rubberlike material; and the strip is provided with a recess 72 at one end for lateral insertion of a latch interposer 24 and an open slot 74 at its opposite end for insertion of a bar magnet 75. In the particular form shown, the cross-sectional dimension of the latch interposer is relatively thin and narrow along the section or portion 76 just forwardly of the latch interposer spring 25'. In turn, the recess 72 is dimensioned to correspond in thickness and width to that of the interposer portion 76 with a slot 78 of limited extent formed at the end of the interposer in communication with the recess and transverse shoulder or abutment 79 extending partially across the end of the holder. As a result, and as viewed from the underside of the printer apparatus shown in FIG. 2, the slotted section 78 of the recess can be lined up with the lower edge of the interposer portion 76 and the holder 70 forced upwardly to cause the interposer portion 76 to advance into the recess 72 until the upper edge of the interposer portion clears the terminal end 79 at which point the holder is snapped in place with the natural tension of the sides of the holder surrounding the recess snugly engaging the sides of the interposer portion 76. The open slot 74 formed along the opposite end of the holder is relatively deep leaving an interconnecting web portion 80 between the recess 72 and slot 74. Preferably the bar magnet 75 is cylindrical in cross section with its diameter about twice the thickness of the interposer section 76 and, to establish snug-fitting insertion of the magnet within the slot 74, the slot is provided with inwardly convergent sides forming inclined surfaces 82 extending inwardly from the end of the slot and terminating in aligned grooves or depressions 84 to accommodate the magnet. Accordingly when the magnet is forced laterally and inwardly against the convergent sides 82 it will cause the sides of the slot 74 to spread until the magnet 75 is advanced into alignment with the grooves 84 whereupon the sides of the slot will contract against the sides of the magnet to clamp it securely in place within the aligned grooves. It will be further noted that the entrance to the slot as defined by the convergent sides 82 is dimensioned along with the magnet 75 to be disposed in surrounding, closely spaced relation to the external surface of the reed switch thereby forming a direct, closed magnetic path from the magnet 75 to the reed elements. Again, the magnet should be aligned within the holder in facing relation to the reed switch such that when the latch interposer is at rest and biased rearwardly the reed elements are normally biased to an open position; but when the latch interposer is advanced forwardly the magnet will pass across the free ends of the reed elements to close the switch.

In assembly, each of the magnet holders 70 is snapped in place on one of the latch interposers 24 and the magnets 74 are inserted within the slots 74 of the magnet holders. The printed circuit board 55 is then mounted by suitable mounting brackets 88 and screws 89 to the frame F and solenoid assembly 58 of the printer unit with the reed switches aligned, as shown in FIG. 3, with each of the respective magnets 75. In this connection, care should be taken in mounting of the printed circuit board to insure that each magnet is arranged in closely spaced, parallel relation to its reed switch, and further that the magnet is positioned and properly aligned within the slot so as to control opening and closing of the reed switch in following the movement of the latch interposer.

Once installed, the magnet holders can be adjusted with respect to the latch interposers by positively forcing the holders along the interposers in either direction, or the magnet may be adjusted within the slot by positively forcing the magnets in an axial direction from either end to obtain the desired alignment with the reed switches. Similarly the printed circuit board mounting brackets 88 will permit a limited degree of adjustment, aided if necessary by the use of shims, to effect the desired alignment with the magnetic actuating members. As one or more latch interposers 24 are advanced forwardly, against the urging of their springs 25', the magnet holders 70 attached to the interposers 24 will be correspondingly advanced with the magnets passing across the reed elements to cause each respective switch to close. The combination of reed switches closed is therefore the same as the combination of interposers advanced by the selector bails 20. Accordingly, each combination of signals produced in response to depression of a key lever is representative of the chosen character and, when transmitted back to the solenoid assembly 58 will cause actuation of the same latch interposers 24 to automatically print the same character. Of course the latch interposers are returned to their original disposition at or near the end of each print cycle to reopen the switches in preparation of the next cycle.

Accordingly it will be seen that the magnetic switch assembly is characterized by its ease of installation with snap-on assembly of the holder and magnets and the magnets being held securely in place by the natural resiliency of the holder material; yet the assembly permits ease of adjustment. Further, the holder will snugly engage the latch interposer under its natural tension, although if desired the holder may be adhesively secured or bonded to the interposer and any necessary adjustment made through adjustment of the magnet. Moreover, the convergent surfaces at the entrance to the slot for the magnet will cooperate in maintaining alignment between the magnet and reed switch as well as to establish a closed magnetic path between the elements. Finally the parts comprising the switch assembly are low in cost and characterized by simplicity of mounting both of the reed switches on the circuit board and of the holders on the latch interposers so as to occupy a minimum of space.

It is to be understood from the foregoing that various modifications and changes may be made in the construction and arrangement of elements comprising the preferred form of present invention, particularly for use in other forms of printer apparatus than that described, without departing from the spirit of the present invention.