US3659163A - Pushbutton variable capacitor - Google Patents

Pushbutton variable capacitor Download PDF

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Publication number
US3659163A
US3659163A US845770A US3659163DA US3659163A US 3659163 A US3659163 A US 3659163A US 845770 A US845770 A US 845770A US 3659163D A US3659163D A US 3659163DA US 3659163 A US3659163 A US 3659163A
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United States
Prior art keywords
push rod
key unit
capacitor
pushbutton key
frame
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Expired - Lifetime
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US845770A
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Konstantin Grigorievic Borisov
Iosif Leibovich Markman
Leonid Semenovich Sitnikov
Lev Lazarevich Utyakov
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
    • H03K17/94—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the way in which the control signals are generated
    • H03K17/965—Switches controlled by moving an element forming part of the switch
    • H03K17/975—Switches controlled by moving an element forming part of the switch using a capacitive movable element
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
    • G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
    • G06F3/02—Input arrangements using manually operated switches, e.g. using keyboards or dials
    • G06F3/0202—Constructional details or processes of manufacture of the input device
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H2239/00—Miscellaneous
    • H01H2239/006—Containing a capacitive switch or usable as such

Definitions

  • ABSTRACT 52 u.s.c
  • APushbum key puter comprising a push rod with a pull-back spring and a mechanical motion-to-electric signal converter associated lg 58
  • F ld is h ..3l7 246,249;200 i66l-l, 181; 1 le o are 340/365 323/93 with said push rod and having the form of a variable capacitor.
  • the pushbutton key is simple in manufacture and reliable in operation.
  • the present invention relates in general to data input devices of, for example, computers, and more particularly is concerned with pushbutton key units of these devices.
  • the invention can also find application in consoles of diverse automatic systems, medical equipment, communications and the like.
  • pushbutton key units for data input devices which comprise a shifting push rod with a pull-back spring mounted in a frame and a mechanical motion-to-electric signal converter associated with said rod.
  • This known signal converter is in the form of a winding on a toroidal core installed in the frame and affected by the field of a permanent magnet mounted on the push rod. Any shift of the push rod results in a corresponding field strength change which causes a certain change of the winding inductance and, hence, of the output signal.
  • an object of the present invention is to overcome the disadvantages associated with the foregoing types of devices.
  • a more specific object of the present invention is to provide a pushbutton key unit for a data input device, which is simple in design and reliable in operation as compared with the known pushbutton key units.
  • a pushbutton key unit for a data input device of, say, a computer incorporating a frame which holds a shifting push rod with a pull-back spring linked with a mechanical motion-to-electric signal converter, wherein said signal converter, according to the present invention, is a capacitor at least one isolated plate of which is mounted on said push rod and at least two other plates are fixed on the frame through an insulating packing.
  • said packing isolating the plate of said capacitor from said push rod serves as a shock absorber.
  • the fixed plates can also be divided into two groups placed in two planes which are perpendicular to the shift line of said push rod and which lie on the opposite sides of the plate attached to said push rod.
  • FIG. 1 illustrates a possible arrangement of a pushbutton key unit of a data input device, according to the invention
  • FIG. 2 is another possible arrangement of a pushbutton key unit of a data input device, according to the invention.
  • the pushbutton key unit incorporates a frame 1 (FIG. 1) holding a push rod 2 with a pull-back spring 3, whereas a mechanical motion-to-electric signal converter is constructed in the form of a capacitor whose moving plate 4 is attached to the push rod 2 and whose fixed plates 5 are located in a plane perpendicular to the shift line of the push rod 2 and fixedly mounted through an insulating packing 6 on the frame 1.
  • the plate 4 is attached to the push rod 2 through a shock-absorbing packing 7 which also serves as an insulator.
  • the plate 4 is coated on its side opposite the push rod 2 with a dielectric layer 8.
  • the number of the plates 4 and 5 in the pushbutton key unit is doubled.
  • the fixed plates 5 are divided into two groups placed in two planes, each of which is perpendicular to the shift line of the push rod, and are fixedly mounted to the frame 1 through insulating packings 6.
  • Each of the moving plates 4 is associated through an insulating packing 7 with the push rod 2, the opposite sides of the plate 4 being coated with a dielectric layer 8.
  • the keyboard of the data input device consists of a set of separate pushbutton key units. Therefore all of the fixed plates 5 can be mounted on a common insulating packing 6, such as a printed board.
  • One of the fixed plates 5 of each pushbutton key unit must be connected to an external source (not shown in the drawing) of an alternative, say, pulse voltage and the other fixed plate 5 must be coupled with the input of an amplifier connected with associated electronics of the data input device (said amplifier and associated electronics are not shown in the drawing).
  • the pushbutton key unit functions in the following way.
  • capacitance C between the fixed plates 5 is at its lowest values and approximately equals:
  • e is the dielectric coefficient of the dielectric layer 8
  • d is the thickness of the dielectric layer 8.
  • the pushbutton key unit shown in FIG. 2 is preferable.
  • This key unit incorporates two capacitors, 9 and 10. The value of the first is highest when the push rod 2 is pressed to the utmost, and the second gains its full value when the push rod 2 is in its initial position, that is, unpressed. Suitable interconnection of the fixed plates 5 of the capacitors 9 and 10 makes it possible to substantially enhance the selection ratio C /C
  • the herein proposed pushbutton key unit of a data input device is of simple construction, reliable in operation, has low overall dimensions and weight and can resist shock and vibration.
  • the pushbutton key unit according to the invention is operable in a wide temperature range.
  • the simplicity of the pushbutton key unit of the present invention insures a high-yield volume production of the device in highly automated production lines.
  • the construction of data input devices comprising a number of keys can be further simplified by using several common printed boards carrying the capacitor fixed plates of all the key units.
  • a pushbutton key unit of a data input device for, say, a computer comprising a frame, a push rod mounted in said frame and capable of moving axially relative to said frame, a pull-back spring for said push rod, a mechanical motion-toelectric signal converter associated with said push rod and comprising a capacitor, at least one isolated substantially rigid plate of said capacitor being mounted on and movable with said push rod and at least two other substantially rigid plates of said capacitor being fixed on said frame through insulating packings and connected to information output means for the data input device.

Abstract

A pushbutton key unit of a data input device for, say, a computer, comprising a push rod with a pull-back spring and a mechanical motion-to-electric signal converter associated with said push rod and having the form of a variable capacitor. The pushbutton key is simple in manufacture and reliable in operation.

Description

United States Patent [151 3,659,163
Borisov et al. 5] Apr. 25, 1972 [541 PUSHBUTTON VARIABLE CAPACITOR [56] References Cited [72] Inventors: Konstantin GrigorievichBorisov, pereulok TED TATE PATENT Zapadny 3, korpus 2; Iosif Leibovich 2 O36 O84 3/1936 Rode 317/249 x M i i Pi a 2,821,609 1/1958 Kessezring ..200/l66 H 6, Leonid Semenovrch sltnrkov, ulitsa Trudovykh Rezervov, 56 12; Lev 2,997,703 8/1961 Powell Lazarevich Utyakov, ulitsa Trudovykh SL 1 Reservov kv. 22, a" of Kiev, a in U.S.S.R.
Primary ExaminerE. A. Goldberg [22] Filed: July 29, 1969 Attorney-Holman and Stern 1 l. .1 2] pp No 845,770 [57] ABSTRACT 52 u.s.c|. ..3l7/249R,200/181,323/93 APushbum key puter, comprising a push rod with a pull-back spring and a mechanical motion-to-electric signal converter associated lg 58 F ld is h ..3l7 246,249;200 i66l-l, 181; 1 le o are 340/365 323/93 with said push rod and having the form of a variable capacitor. The pushbutton key is simple in manufacture and reliable in operation.
4 Claims, 2 Drawing Figures The present invention relates in general to data input devices of, for example, computers, and more particularly is concerned with pushbutton key units of these devices. The invention can also find application in consoles of diverse automatic systems, medical equipment, communications and the like.
Known in the art are pushbutton key units for data input devices, which comprise a shifting push rod with a pull-back spring mounted in a frame and a mechanical motion-to-electric signal converter associated with said rod.
This known signal converter is in the form of a winding on a toroidal core installed in the frame and affected by the field of a permanent magnet mounted on the push rod. Any shift of the push rod results in a corresponding field strength change which causes a certain change of the winding inductance and, hence, of the output signal.
Because of the relatively great number of mechanical parts, inductances as well as precise subassemblies, requiring individual adjustment, the known pushbutton key units are difficult and costly to manufacture and insufi'lciently reliable.
Accordingly, an object of the present invention is to overcome the disadvantages associated with the foregoing types of devices.
A more specific object of the present invention is to provide a pushbutton key unit for a data input device, which is simple in design and reliable in operation as compared with the known pushbutton key units.
These and other objects are achieved by providing a pushbutton key unit for a data input device of, say, a computer incorporating a frame which holds a shifting push rod with a pull-back spring linked with a mechanical motion-to-electric signal converter, wherein said signal converter, according to the present invention, is a capacitor at least one isolated plate of which is mounted on said push rod and at least two other plates are fixed on the frame through an insulating packing.
In accordance with one form of the invention, said packing isolating the plate of said capacitor from said push rod serves as a shock absorber.
It is also expedient to place the fixed plates of said capacitor in a plane perpendicular to the shift line of said push rod.
The fixed plates can also be divided into two groups placed in two planes which are perpendicular to the shift line of said push rod and which lie on the opposite sides of the plate attached to said push rod.
Embodiments of the invention will now be described with reference to the accompanying drawings, in which:
FIG. 1 illustrates a possible arrangement of a pushbutton key unit of a data input device, according to the invention, and
FIG. 2 is another possible arrangement of a pushbutton key unit of a data input device, according to the invention.
The pushbutton key unit incorporates a frame 1 (FIG. 1) holding a push rod 2 with a pull-back spring 3, whereas a mechanical motion-to-electric signal converter is constructed in the form of a capacitor whose moving plate 4 is attached to the push rod 2 and whose fixed plates 5 are located in a plane perpendicular to the shift line of the push rod 2 and fixedly mounted through an insulating packing 6 on the frame 1. The plate 4 is attached to the push rod 2 through a shock-absorbing packing 7 which also serves as an insulator. The plate 4 is coated on its side opposite the push rod 2 with a dielectric layer 8.
In another embodiment of the present invention (FIG. 2) the number of the plates 4 and 5 in the pushbutton key unit is doubled. The fixed plates 5 are divided into two groups placed in two planes, each of which is perpendicular to the shift line of the push rod, and are fixedly mounted to the frame 1 through insulating packings 6. Each of the moving plates 4 is associated through an insulating packing 7 with the push rod 2, the opposite sides of the plate 4 being coated with a dielectric layer 8.
The keyboard of the data input device consists of a set of separate pushbutton key units. Therefore all of the fixed plates 5 can be mounted on a common insulating packing 6, such as a printed board.
One of the fixed plates 5 of each pushbutton key unit must be connected to an external source (not shown in the drawing) of an alternative, say, pulse voltage and the other fixed plate 5 must be coupled with the input of an amplifier connected with associated electronics of the data input device (said amplifier and associated electronics are not shown in the drawing).
The pushbutton key unit functions in the following way.
When the push rod 2 is in its initial position, capacitance C between the fixed plates 5 is at its lowest values and approximately equals:
c ,,,4.43 10' s/d,), where S is the area of the fixed plate 5, d is the maximum space between the planes of the fixed plate 5 and the moving plate 4.
When S=0.5 sq. cm and d,=0.5 cm, C QZ pF.
When the push rod 2 is pressed the value of capacitance C between the fixed plates is detennined by the equation:
e is the dielectric coefficient of the dielectric layer 8,
d is the thickness of the dielectric layer 8.
When F5 and d =0.005 cm, C,,,,,,=22 pF. In this case capacitance selection ratio C /C is equal to l 10.
Where said selection ratio is insufficient, the pushbutton key unit shown in FIG. 2 is preferable. This key unit incorporates two capacitors, 9 and 10. The value of the first is highest when the push rod 2 is pressed to the utmost, and the second gains its full value when the push rod 2 is in its initial position, that is, unpressed. Suitable interconnection of the fixed plates 5 of the capacitors 9 and 10 makes it possible to substantially enhance the selection ratio C /C The herein proposed pushbutton key unit of a data input device is of simple construction, reliable in operation, has low overall dimensions and weight and can resist shock and vibration.
The pushbutton key unit according to the invention is operable in a wide temperature range.
The simplicity of the pushbutton key unit of the present invention insures a high-yield volume production of the device in highly automated production lines. Besides, the construction of data input devices comprising a number of keys can be further simplified by using several common printed boards carrying the capacitor fixed plates of all the key units.
We claim:
1. A pushbutton key unit of a data input device for, say, a computer, comprising a frame, a push rod mounted in said frame and capable of moving axially relative to said frame, a pull-back spring for said push rod, a mechanical motion-toelectric signal converter associated with said push rod and comprising a capacitor, at least one isolated substantially rigid plate of said capacitor being mounted on and movable with said push rod and at least two other substantially rigid plates of said capacitor being fixed on said frame through insulating packings and connected to information output means for the data input device.
2. A pushbutton key unit as claimed in claim 1, in which said packing isolating said capacitor plate from said push rod comprises a shock-absorbing material.
3. A pushbutton key unit as claimed in claim 1, in which said fixed plates lie in a single common plane which is perpendicular to the shift line of said push rod.
4. A pushbutton key unit as claimed in claim 1, in which said fixed plates are divided into two groups which are placed in two planes perpendicular to the shift line of said push rod and lie on the opposite sides of said isolated plate attached to said push rod.
il R k

Claims (4)

1. A pushbutton key unit of a data input device for, say, a computer, comprising a frame, a push rod mounted in said frame and capable of moving axially relative to said frame, a pull-back spring for said push rod, a mechanical motion-to-electric signal converter associated with said push rod and comprising a capacitor, at least one isolated substantially rigid plate of said capacitor being mounted on and movable with said push rod and at least two other substantially rigid plates of said capacitor being fixed on said frame through insulating packings and connected to information output means for the data input device.
2. A pushbutton key unit as claimed in claim 1, in which said packing isolating said capacitor plate from said push rod comprises a shock-absorbing material.
3. A pushbutton key unit as claimed in claim 1, in which said fixed plates lie in a single common plane which is perpendicular to the shift line of said push rod.
4. A pushbutton key unit as claimed in claim 1, in which said fixed plates are divided into two groups which are placed in two planes perpendicular to the shift line of said push rod and lie on the opposite sides of said isolated plate attached to said push rod.
US845770A 1969-07-29 1969-07-29 Pushbutton variable capacitor Expired - Lifetime US3659163A (en)

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Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3751612A (en) * 1971-08-30 1973-08-07 Colorado Instr Inc Snap action capacitive type switch
US3760243A (en) * 1972-09-21 1973-09-18 Gen Electric Capacitive keyswitch
US3886866A (en) * 1972-11-24 1975-06-03 Us Navy Capacitor - contact fuze system
US3912988A (en) * 1973-01-29 1975-10-14 Fischer & Porter Co Capacitive detector for an electronic differential pressure transmitter
US3943812A (en) * 1973-11-02 1976-03-16 Nippon Gakki Seizo Kabushiki Kaisha Touch responsive sensor in electronic keyboard musical instrument
US3951250A (en) * 1973-04-06 1976-04-20 Alphameric Keyboards Limited Capacitive key for electronic circuit
US3965399A (en) * 1974-03-22 1976-06-22 Walker Jr Frank A Pushbutton capacitive transducer
US4032804A (en) * 1976-06-22 1977-06-28 Wagner Gilbert F Ultrasensitive differential relay configuration
US4034234A (en) * 1975-01-10 1977-07-05 Texas Instruments Incorporated Switching module for solid-state keyboard
US4209819A (en) * 1978-03-13 1980-06-24 Key Tronic Corporation Capacitive keyswitch
US4211915A (en) * 1978-12-04 1980-07-08 General Electric Company Keyboard verification system
USRE30435E (en) * 1973-02-23 1980-11-11 Brother Kogyo Kabushiki Kaisha Keyboard switch arrangement and key switch useable therein
US4458293A (en) * 1981-11-05 1984-07-03 Cherry Electrical Products Corporation Capacitive keyboard
US4466046A (en) * 1982-05-17 1984-08-14 Cherry Electrical Products Corporation Capacitive keyboard switch
US4472758A (en) * 1982-04-30 1984-09-18 Brother Kogyo Kabushiki Kaisha Capacitive switching device
US20120194306A1 (en) * 2011-02-01 2012-08-02 Maxim Integrated Products, Inc. Preventing contact stiction in micro relays
CN105405653A (en) * 2015-11-13 2016-03-16 太仓荣中机电科技有限公司 Fine tuning type capacitor

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2036084A (en) * 1933-12-20 1936-03-31 Gen Electric Coupling
US2821609A (en) * 1953-05-07 1958-01-28 Fkg Fritz Kesselring Geratebau Rectifier contact structure
US2997703A (en) * 1956-08-03 1961-08-22 Clary Corp Keyboard controlled circuitry
US3142981A (en) * 1960-11-22 1964-08-04 Performance Measurements Compa Digital force transducer
US3293640A (en) * 1964-05-22 1966-12-20 Chalfin Albert Electronic systems keyboard and switch matrix

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2036084A (en) * 1933-12-20 1936-03-31 Gen Electric Coupling
US2821609A (en) * 1953-05-07 1958-01-28 Fkg Fritz Kesselring Geratebau Rectifier contact structure
US2997703A (en) * 1956-08-03 1961-08-22 Clary Corp Keyboard controlled circuitry
US3142981A (en) * 1960-11-22 1964-08-04 Performance Measurements Compa Digital force transducer
US3293640A (en) * 1964-05-22 1966-12-20 Chalfin Albert Electronic systems keyboard and switch matrix

Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3751612A (en) * 1971-08-30 1973-08-07 Colorado Instr Inc Snap action capacitive type switch
US3760243A (en) * 1972-09-21 1973-09-18 Gen Electric Capacitive keyswitch
US3886866A (en) * 1972-11-24 1975-06-03 Us Navy Capacitor - contact fuze system
US3912988A (en) * 1973-01-29 1975-10-14 Fischer & Porter Co Capacitive detector for an electronic differential pressure transmitter
USRE30435E (en) * 1973-02-23 1980-11-11 Brother Kogyo Kabushiki Kaisha Keyboard switch arrangement and key switch useable therein
US3951250A (en) * 1973-04-06 1976-04-20 Alphameric Keyboards Limited Capacitive key for electronic circuit
US3943812A (en) * 1973-11-02 1976-03-16 Nippon Gakki Seizo Kabushiki Kaisha Touch responsive sensor in electronic keyboard musical instrument
US3965399A (en) * 1974-03-22 1976-06-22 Walker Jr Frank A Pushbutton capacitive transducer
US4034234A (en) * 1975-01-10 1977-07-05 Texas Instruments Incorporated Switching module for solid-state keyboard
US4032804A (en) * 1976-06-22 1977-06-28 Wagner Gilbert F Ultrasensitive differential relay configuration
US4209819A (en) * 1978-03-13 1980-06-24 Key Tronic Corporation Capacitive keyswitch
US4211915A (en) * 1978-12-04 1980-07-08 General Electric Company Keyboard verification system
US4458293A (en) * 1981-11-05 1984-07-03 Cherry Electrical Products Corporation Capacitive keyboard
US4472758A (en) * 1982-04-30 1984-09-18 Brother Kogyo Kabushiki Kaisha Capacitive switching device
US4466046A (en) * 1982-05-17 1984-08-14 Cherry Electrical Products Corporation Capacitive keyboard switch
US20120194306A1 (en) * 2011-02-01 2012-08-02 Maxim Integrated Products, Inc. Preventing contact stiction in micro relays
CN105405653A (en) * 2015-11-13 2016-03-16 太仓荣中机电科技有限公司 Fine tuning type capacitor
CN105405653B (en) * 2015-11-13 2018-05-08 太仓荣中机电科技有限公司 A kind of fine adjustment type capacitor

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