KEY OPERATED PULSE GENERATING DEVICE
United States Patent 3693033
A key operated electric pulse generator comprising a housing of non-magnetic material supporting depressible key at one end, a coil at the other end, and a body of magnetic material spaced from the coil. A permanent magnet is supported in the housing for movement between the magnetic body and the coil and is normally magnetically attracted to the magnetic body. A spring is interposed between the permanent magnet and the depressible key so that upon depression of the key the spring will yield a certain amount and then cause the magnet to abruptly release from the magnetic body and be impelled toward the coil to generate an electric signal.
US Patent References:
Force responsive electrical impulse generator
Blodgett et al. - December 1963 - 3116428
Pulse generator
Speiser et al. - November 1962 - 3065366
Electrical impulse generator
Harnau et al. - August 1968 - 3398302
Inertia electro-magnetic generator
Branagan et al. - October 1964 - 3153735
Motion e.m.f. generating transducer
Abel et al. - May 1964 - 3132268
Force responsive electrical impulse generator
Blodgett et al. - December 1963 - 3116428
Pulse generator
Speiser et al. - November 1962 - 3065366
Electrical impulse generator
Harnau et al. - August 1968 - 3398302
Inertia electro-magnetic generator
Branagan et al. - October 1964 - 3153735
Motion e.m.f. generating transducer
Abel et al. - May 1964 - 3132268
Application Number:
05/156318
Publication Date:
09/19/1972
Filing Date:
06/24/1971
View Patent Images:
Export Citation:
Assignee:
Electromechanisms, Inc. (Azusa, CA)
Primary Class:
Other Classes:
310/15
International Classes:
H02K35/02; H02K39/00; H02K35/00; H02K35/00
Field of Search:
310/12-15,30
Primary Examiner:
Duggan D. F.
Claims:
I claim
1. A pulse generating device comprising a housing,
2. A pulse generating device according to claim 1 comprising a member of magnetic material having relatively low magnetic retentivity attached to one end of said magnet and engagable with said body when said magnet is attracted to said body.
3. A pulse generating device according to claim 1 wherein said body is cup-shaped and has a radially inwardly extending end,
4. A pulse generating device according to claim 3 comprising a core within said coil,
1. A pulse generating device comprising a housing,
2. A pulse generating device according to claim 1 comprising a member of magnetic material having relatively low magnetic retentivity attached to one end of said magnet and engagable with said body when said magnet is attracted to said body.
3. A pulse generating device according to claim 1 wherein said body is cup-shaped and has a radially inwardly extending end,
4. A pulse generating device according to claim 3 comprising a core within said coil,
Description:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to key controlled electric pulse generating means.
2. Description of the Prior Art
Heretofore, manually controlled electric pulse or signal transmitting devices for controlling electronic or the like equipment generally comprised key operated contact opening or closing devices. Such devices require a standby electrical circuit which is made or broken by depression of a key. Also, the contacts of such switches tend to wear and to become oxidized or corroded after extensive use, resulting in unreliable switching operation. Further, such contacts tend to "bounce", which, when the contacts are in circuit with sensitive electronic equipment, gives rise to spurious and unwanted pulse signals.
Attempts have been made to overcome the above problems by providing a key operated permanent magnet which is moveable relative to a coil to generate an electric signal as the magnetic field of the magnet cuts across the windings of the coil. Although such pulse generating devices work generally satisfactorily, the size and wave form of the signal generated is dependent upon the speed and abruptness with which the key is depressed. Thus, if the key is depressed too slowly, the resulting signal may be of insufficient size or shape to adequately and reliably control a signal responsive device.
SUMMARY OF THE INVENTION
The present invention overcomes the above problem by providing a permanent magnet which is coupled to a depressible key through a yieldable spring, and which by virtue of its magnetic attraction to a stationary magnetic body, forms the sole means of maintaining itself spaced from an electric signal generating coil. Upon a predetermined depression of the key and consequent deformation of the spring, the magnet will abruptly release from the body and will advance toward the coil at a maximum rate under the impetus of the spring to generate a sharply peaked signal pulse. It should be noted that the size and shape of the wave form of such generated signal pulse will be substantially consistent regardless of the speed or abruptness with which the key is depressed. Further, applicant's construction results in a compact, self-contained pulse generating device which is adapted to be easily and readily mounted on a panel or the like. The construction also results in a compact and economically manufactured and assembled device having relatively few moving parts, has an extremely long operating life and may be safely used in explosive and other dangerous environments.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a longitudinal sectional view through a key operated pulse generating device embodying a preferred form of the present invention.
FIG. 2 is a transverse sectional view taken substantially along the line 2--2 of FIG. 1.
FIG. 3 is a diagram of a wave form generated by the device of FIGS. 1 and 2 .
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to the drawing, the device comprises a hollow cylindrical housing 11 which is preferably molded of plastic or other non-magnetic material. The housing is reduced in diameter at its righthand end and has a threaded section 12 adapted to be mounted in an opening in a panel or other supporting member 13. The housing is secured to the panel by lock nuts 14 and 15 threaded on the section 12.
A depressible key comprising a tubular keystem 16, also of plastic and having a key top 17 attached to its outer end, is slideable endwise in a bore 18 formed in the housing. The inner end of the keystem 16 has a flange 20 normally abutting a shoulder 21 in the housing to limit movement of the key.
A cylindrical cavity 22 is formed in the housing and communicates with the bore 18 through an intermediate cylindrical cavity 23.
A cup shaped magnetic body comprising a disc 24 and a ring 25 fitted in the cavity 22 is held in place against a shoulder 29 by a plastic ring 26 and a coil bobbin 27, the latter being press fitted in the cavity 22.
The bobbin 27 comprises a tubular core 28 of magnetic material having a low magnetic retentivity and a high magnetic permeability, such as is commercially available under the trade name "Armco" iron. The core 28 is supported at opposites ends by flanges 30 and 31 of plastic or other non-magnetic material. A coil 32 of wire is wound on the core 28 and its ends are electrically connected to terminal strips 33 and 34 for connection to a suitable circuit (not shown) to be controlled by depression of the key.
The disc 24 and ring 25 are formed of magnetic material, such as "Armco" iron, having a low magnetic retentivity.
A plunger 35 of non-magnetic material, such as brass, is slideably mounted at one end thereof in the core 28 and at the opposite end thereof in the keystem 16 for endwise movement. An annular permanent magnet 36 is mounted on the plunger and is held between annular discs 37 and 38, which, in turn, are held in place on the plunger by two spring clips 40 and 41 of non-magnetic material. The magnet 36 is formed of a magnetic material having a high degree of magnetic retentivity, such as is available under the trade name "Alnico" and the discs 37 and 38 are formed of a magnetic material, such as "Armco" iron, having a low magnetic retentivity and high permeability.
A compression spring 42 surrounds the plunger 35 and extends between the clip 41 and the flange 20 of the keystem 16.
Normally, when the key 17 is in its illustrated undepressed condition, the magnet 36 is attracted to the disc 24, thus lightly compressing the spring 42 to hold the key in its outer illustrated undepressed position. In such condition, the magnet 36 and discs 37 and 35 are maintained within the ring 25 and the magnetic flux developed by the magnet extends generally through the disc 38, disc 24, ring 25 and across the annular air gap 43 to the disc 37. The discs 37 and 38 tend to concentrate the magnetic flux therethrough and convey the same to and from the magnet 36.
Upon depression of the key 17 through the latter portion of its full stroke and consequent compression of the spring 42, the latter suddenly overcomes the force of attraction of the magnet 36 and impels the magnet and the plunger 35 at a high rate of speed towards the coil 32. Accordingly, the magnetic flux path abruptly changes due to the increasing air gap between the discs 24 and 38 and the receding of the magnet from within the ring 25. The flux path now abruptly expands endwise toward the coil 32. At the same time, due to the rapid movement of the magnet 36 toward the coil, the lines of force of the magnetic flux rapidly cut across the windings of the coil to develop an electric pulse or signal having a sharply peaked rise in voltage as depicted in FIG. 3. The core 28 tends to convey the lines of magnetic force therealong to distribute the same throughout the coil 32.
FIG. 3 illustrates wave form developed from a device constructed according to FIG. 1 having a coil 32 formed of No. 46 copper wire with a total resistance of 3,000 ohms.
Upon release of the key 17 from depressed position, the magnet will again attract to the disc 24 and the ring 25 to return the parts to their illustrated positions.
1. Field of the Invention
This invention relates to key controlled electric pulse generating means.
2. Description of the Prior Art
Heretofore, manually controlled electric pulse or signal transmitting devices for controlling electronic or the like equipment generally comprised key operated contact opening or closing devices. Such devices require a standby electrical circuit which is made or broken by depression of a key. Also, the contacts of such switches tend to wear and to become oxidized or corroded after extensive use, resulting in unreliable switching operation. Further, such contacts tend to "bounce", which, when the contacts are in circuit with sensitive electronic equipment, gives rise to spurious and unwanted pulse signals.
Attempts have been made to overcome the above problems by providing a key operated permanent magnet which is moveable relative to a coil to generate an electric signal as the magnetic field of the magnet cuts across the windings of the coil. Although such pulse generating devices work generally satisfactorily, the size and wave form of the signal generated is dependent upon the speed and abruptness with which the key is depressed. Thus, if the key is depressed too slowly, the resulting signal may be of insufficient size or shape to adequately and reliably control a signal responsive device.
SUMMARY OF THE INVENTION
The present invention overcomes the above problem by providing a permanent magnet which is coupled to a depressible key through a yieldable spring, and which by virtue of its magnetic attraction to a stationary magnetic body, forms the sole means of maintaining itself spaced from an electric signal generating coil. Upon a predetermined depression of the key and consequent deformation of the spring, the magnet will abruptly release from the body and will advance toward the coil at a maximum rate under the impetus of the spring to generate a sharply peaked signal pulse. It should be noted that the size and shape of the wave form of such generated signal pulse will be substantially consistent regardless of the speed or abruptness with which the key is depressed. Further, applicant's construction results in a compact, self-contained pulse generating device which is adapted to be easily and readily mounted on a panel or the like. The construction also results in a compact and economically manufactured and assembled device having relatively few moving parts, has an extremely long operating life and may be safely used in explosive and other dangerous environments.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a longitudinal sectional view through a key operated pulse generating device embodying a preferred form of the present invention.
FIG. 2 is a transverse sectional view taken substantially along the line 2--2 of FIG. 1.
FIG. 3 is a diagram of a wave form generated by the device of FIGS. 1 and 2 .
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to the drawing, the device comprises a hollow cylindrical housing 11 which is preferably molded of plastic or other non-magnetic material. The housing is reduced in diameter at its righthand end and has a threaded section 12 adapted to be mounted in an opening in a panel or other supporting member 13. The housing is secured to the panel by lock nuts 14 and 15 threaded on the section 12.
A depressible key comprising a tubular keystem 16, also of plastic and having a key top 17 attached to its outer end, is slideable endwise in a bore 18 formed in the housing. The inner end of the keystem 16 has a flange 20 normally abutting a shoulder 21 in the housing to limit movement of the key.
A cylindrical cavity 22 is formed in the housing and communicates with the bore 18 through an intermediate cylindrical cavity 23.
A cup shaped magnetic body comprising a disc 24 and a ring 25 fitted in the cavity 22 is held in place against a shoulder 29 by a plastic ring 26 and a coil bobbin 27, the latter being press fitted in the cavity 22.
The bobbin 27 comprises a tubular core 28 of magnetic material having a low magnetic retentivity and a high magnetic permeability, such as is commercially available under the trade name "Armco" iron. The core 28 is supported at opposites ends by flanges 30 and 31 of plastic or other non-magnetic material. A coil 32 of wire is wound on the core 28 and its ends are electrically connected to terminal strips 33 and 34 for connection to a suitable circuit (not shown) to be controlled by depression of the key.
The disc 24 and ring 25 are formed of magnetic material, such as "Armco" iron, having a low magnetic retentivity.
A plunger 35 of non-magnetic material, such as brass, is slideably mounted at one end thereof in the core 28 and at the opposite end thereof in the keystem 16 for endwise movement. An annular permanent magnet 36 is mounted on the plunger and is held between annular discs 37 and 38, which, in turn, are held in place on the plunger by two spring clips 40 and 41 of non-magnetic material. The magnet 36 is formed of a magnetic material having a high degree of magnetic retentivity, such as is available under the trade name "Alnico" and the discs 37 and 38 are formed of a magnetic material, such as "Armco" iron, having a low magnetic retentivity and high permeability.
A compression spring 42 surrounds the plunger 35 and extends between the clip 41 and the flange 20 of the keystem 16.
Normally, when the key 17 is in its illustrated undepressed condition, the magnet 36 is attracted to the disc 24, thus lightly compressing the spring 42 to hold the key in its outer illustrated undepressed position. In such condition, the magnet 36 and discs 37 and 35 are maintained within the ring 25 and the magnetic flux developed by the magnet extends generally through the disc 38, disc 24, ring 25 and across the annular air gap 43 to the disc 37. The discs 37 and 38 tend to concentrate the magnetic flux therethrough and convey the same to and from the magnet 36.
Upon depression of the key 17 through the latter portion of its full stroke and consequent compression of the spring 42, the latter suddenly overcomes the force of attraction of the magnet 36 and impels the magnet and the plunger 35 at a high rate of speed towards the coil 32. Accordingly, the magnetic flux path abruptly changes due to the increasing air gap between the discs 24 and 38 and the receding of the magnet from within the ring 25. The flux path now abruptly expands endwise toward the coil 32. At the same time, due to the rapid movement of the magnet 36 toward the coil, the lines of force of the magnetic flux rapidly cut across the windings of the coil to develop an electric pulse or signal having a sharply peaked rise in voltage as depicted in FIG. 3. The core 28 tends to convey the lines of magnetic force therealong to distribute the same throughout the coil 32.
FIG. 3 illustrates wave form developed from a device constructed according to FIG. 1 having a coil 32 formed of No. 46 copper wire with a total resistance of 3,000 ohms.
Upon release of the key 17 from depressed position, the magnet will again attract to the disc 24 and the ring 25 to return the parts to their illustrated positions.