Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H13/00—Switches having rectilinearly-movable operating part or parts adapted for pushing or pulling in one direction only, e.g. push-button switch
  • H01H13/70—Switches having rectilinearly-movable operating part or parts adapted for pushing or pulling in one direction only, e.g. push-button switch having a plurality of operating members associated with different sets of contacts, e.g. keyboard
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H9/00—Details of switching devices, not covered by groups H01H1/00 - H01H7/00
  • H01H9/02—Bases, casings, or covers
  • H01H9/0271—Bases, casings, or covers structurally combining a switch and an electronic component
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H2221/00—Actuators
  • H01H2221/036—Return force
  • H01H2221/04—Return force magnetic
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H2225/00—Switch site location
  • H01H2225/012—Switch site location normally closed
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H2239/00—Miscellaneous
  • H01H2239/02—Other elements in moving part

Definitions

• the invention relates to a new type of control keyboard, of simple and inexpensive design, as well as machines and equipment provided with such a keyboard.
• Prior art :
• a control keyboard is a relatively expensive sub-assembly and of fairly poor reliability compared to that of electronic equipment, in particular the digital logic circuits, which are associated with it. installations, the keyboard is often the weak link in the system.
• the most basic keyboard models use a simple switch, capable of transmitting a voltage, functionally coupled with each key, to translate the manual depressing of the key into a usable electrical signal.
• the difficulty comes mainly from the fact that the electrical contact is more or less straightforward when the switch is closed, that is to say when the corresponding key is pressed.
• the electronic coding circuits associated with the keyboard are complex and expensive.
• the fundamental principle of the invention arises from the simple observation that it is easier, at the level of the electronic processing circuits, to detect an absence of signal (that is to say, the opening of a switch normally closed) than a signal transmitted through an improperly established electrical contact (ie the faulty closing of a normally open switch).
• the invention proposes to use switches with a mechanical structure (for reasons of cost price), with normally closed contact (for reasons of reliability) interconnected with a network of conductors in a matrix configuration ( to simplify the wiring of the keyboard itself).
• this triple object is achieved by a keyboard structure with keys, each key being provided with a magnetic means for returning to the rest position and being functionally coupled to at least one unipolar switch, of the type according to which said switches are electrically connected to a network of conductors in a matrix configuration with m lines and n columns, each line and each column being materialized by a conductor so that a switch of coordinates i, j is connected between line i and the column j from the network; characterized in that said switches are of the contact type normally closed, that a diode element is connected in series with each switch, in the switch itself, and that each diode element and coordinate switch i, j is interconnected between the conductor of line i and that of column j of said network; the direction of connection of the diodes being identical between the rows and columns.
• the essential advantage of the invention is that the minimum duration of the signal produced by pressing a key is predetermined and independent of the operator. This minimum duration is moreover very much greater than that of the parasitic signals produced in the prior art, by shocks, vibrations, or "rebounds".
• the invention thus makes it possible to avoid all the problems of distinction between real signal and spurious signal, and it makes it possible to associate with the keyboard coding devices much simpler and much less expensive than in the prior art In fact, it has been found in practice, the price of the necessary coding devices was divided by 5 or 6, which constitutes an extremely important technical advance.
• the invention also relates to any keyboard machine characterized in that it is provided with a keyboard according to the above definition and in that it further comprises a signal generator with multiplexed outputs whose said outputs are connected to the conductors of the lines (or columns) of said keyboard, a signal analyzer with multiplexed inputs whose said inputs are connected to the conductors of the columns (or lines, respectively) of said keyboard, first sequential control means connected to said signal analyzer and second sequential control means connected to said signal generator; said first and second control means having different operating frequencies.
• Multiplexed outputs means that the signal generator is designed to cause a significant electrical signal to appear sequentially and cyclically on all outputs, with a determined scanning frequency.
• multiplexed inputs means that the signal analyzer is designed to measure the signals applied to its inputs sequentially and cyclically, with a determined scanning frequency.
• the scanning frequency of the analyzer is much higher than that of the generator so that when a signal is momentarily generated at one of the generator outputs, the analyzer has time to explore all of its inputs.
• Each key Ti, j of the keyboard forms in fact a single-pole switch Ii, j with simple mechanical structure.
• Each button is provided with a return means in the rest position (not shown) which is of a "magnetic return” type such as that described in French patent application No. 78 33-733 filed on November 29 1978 in the name of the applicant. It is also perfectly conceivable to use a pusher means independent of the switch proper which can then be a sub-assembly of the "micro-contact” type or the like.
• the keyboard 11 comprises a network 12 of conductors in a matrix configuration, that is to say comprising m rows and n columns, each row and each column being embodied by a conductor electrically independent of the others.
• other circuit branches including in particular the aforementioned single-pole switches.
• the expression "network of conductors in matrix configuration” does not mean that the device of the invention has a particular configuration of wiring and in particular a cross configuration as illustrated in FIG. 1. The configuration crossover is however technologically advantageous.
• matrix configuration we simply mean that two groups of conductors have been defined (conveniently called “rows” and “columns”) so as to produce at least some of the possible selective interconnections between rows and columns, in particular by means of single pole switches.
• each switch associated or combined with each key T can be defined by its coordinates (i, j) so that the switch Ii, j is the one which is connected to the conductor forming the line i and to the conductor forming the column j.
• the switches Ii, j are of the "normally closed contact" type and comprising a diode element Di, j connected in series in each switch between the two contacts so that each series connection of a diode Di, j and of a switch Ii, j is interconnected between the conductor of line i and that of column j.
• the direction of connection of the diodes is identical between rows and columns.
• the anodes of the diodes are all connected to the conductors defining the columns.
• each key Ti, j comprising the switch Ii, j and the diode Di, J associated in a compact assembly.
• each key Ti, j comprises a lower core 15 performing a guiding function in a support plate 16 whose lower face can for example be arranged in a printed circuit carrying the conductors L i and C j .
• the core 15 also forms a movable contact part capable of coming into contact in the rest position (as shown in FIG. 2) with the conductors L i , and C j , respectively.
• the movable contact part comprises an insulating part 15 a forming the main part of the core and two conductive elements 19, 20 electrically isolated and spaced from one another and projecting laterally with respect to to the core 1.5 so as to be able to come into contact with the conductors Li and Cj, respectively; while the diode Di, j is connected between the two conductive elements 19, 20 preferably being embedded in the heart of the insulating part 15 '.
• the latter also constitutes an anchoring support for the two conductive elements 19, 20 held in this way spaced from one another.
• This electronic system includes a signal generator 25 with multiplexed outputs and an analyzer signal 26 with multiplexed inputs; these two devices corresponding to the above definition.
• the signal generator 25 therefore has four multiplexed outputs S 1 , S 2 , S 3 , S 4 , connected respectively to the line conductors L 1 , L 2 , L 3 , L 4 , while the signal analyzer has four inputs multiplexed E 1 , E 2 , E 3 , E 4 , respectively connected to the column conductors C 1 , C 2 , C 3 , C 4.
• the inputs E 1 -E 4 each receive a constant voltage applied by the intermediate of resistors R 1 , R 2 , R 3 , R 4 respectively, connected to a positive voltage source + V.
• the resistors R 1 -R 4 all have the same value.
• the signal generator could just as easily be connected to the column conductors and the signal analyzer could also be connected to the line conductors.
• the signal generator 25 includes a reference input E 0 connected to a reference potential V 0 (preferably, the input E 0 is connected to ground) and the entire operation of the generator 25 is reduced to making sequentially and cyclically the input E 0 to the different outputs S 1 -S 4 in a chosen order.
• the switching operations carried out by the signal generator are controlled by pulses applied to a control input e 2 .
• the signal analyzer has a control input e 1 receiving control pulses, setting the rate with which the inputs E 1 -E 4 will be successively explored and analyzed.
• the input e 1 is connected to a first sequential control means consisting of a clock H and a first counter 28 while the input e 2 is connected to a second sequential control means (combined with the first) consisting of the H clock and counters 28 and 29 connected in cascade.
• the operating frequency of said first sequential piloting means is higher than the operating frequency of said second sequential piloting means and these operating frequencies fix the rhythm of the analysis of the states of the inputs E 1 -E 4 on the one hand and the rhythm of the sequential switching of the voltage V 0 to the different outputs S 1 -S 4 on the other hand.
• the ratio of the two operating frequencies is at least equal to the number of multiplexed inputs of said signal analyzer, so that the latter has time to "explore" all of the inputs E 1 -E 4 during the time interval in which voltage V 0 is present at one of the outputs S 1 -S 4 .
• a prototype has been produced in which the counter 28 supplies control pulses at 50 kHz and in which the counter 29 supplies control pulses at 5 kHz.
• a keyboard according to the invention has extremely significant technical advantages compared to keyboards of the prior art.
• the minimum duration of the signal produced by pressing a key is predetermined and is completely independent of the operator.
• This technical result is obtained by the combination of the magnetic system for recalling the keys in the rest position, with the fact that the keys are with normally closed contact in the rest position.
• the restoring force acting on each key is maximum when the key is in the rest position, and gradually decreases as the key is pressed.
• a pressing force must be applied to the key which must be greater than a predetermined minimum value.
• the key is depressed, and continues to depress even if the depressing force applied to it becomes zero.
• the button has started to press, its contact is opened, and a signal is produced.
• the signal is produced during the whole time the button is pressed and the button returns to its rest position.
• the duration of the signal is approximately equal to the duration of the return movement of the key.
• the minimum duration of said signal therefore depends solely on the structure of the keyboard and is therefore completely independent of the operator. As this minimum signal duration is always much greater than that of spurious signals (produced by shocks, vibrations, by the phenomenon of rebounds on the mechanical contacts), it is no longer necessary to use electronic circuits.
• the invention therefore makes it possible to use very simplified coding circuits, which are much less expensive than the coding circuits used in the prior art.
• the restoring force applied to a key is maximum when the key is in the position of rest, and the contacts are normally closed in the rest position, the pressing force that an operator must apply to a key must be at least greater than the magnetic restoring force applied to the key, that is to say say that the driving force applied by the operator must be relatively large. This eliminates, due to this significant driving force, the major part of the rebound phenomena which normally occur at the opening of the mechanical contacts.
• the magnetic restoring force is maximum when the contacts are closed, the pressure force between the closed contacts is very high, which makes it possible to use an extremely simple printed circuit to form the matrix network of the lines and above columns, and one can use for example a screen printing technique with conductive ink. This technique can however only be used if the printed circuit does not include any component.
• a keyboard according to the invention in which the components (that is to say the diodes) are provided inside the keys.
• the keyboard according to the invention is of the logic type, that is to say that its outputs can only have two states: 0 and 1.
• the three characteristic factors of a keyboard with movable keys (which are the distance of movement of the keys, the contact pressures, and the minimum duration of the signal produced by pressing a key) have limit values which are completely independent of the operator, and that the operator can only, by operating the keys in various ways, improve these three characteristic factors.

Landscapes

• Input From Keyboards Or The Like (AREA)
• Push-Button Switches (AREA)
• Electronic Switches (AREA)
• Electrophonic Musical Instruments (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (1)

Family

ID=9220858

Family Applications (1)

Country Status (12)

Cited By (1)

Families Citing this family (6)

Citations (5)

Family Cites Families (2)

• 1979
  • 1979-01-17 FR FR7901101A patent/FR2447089A1/fr active Granted
  • 1979-04-03 US US06/026,763 patent/US4288787A/en not_active Expired - Lifetime
• 1980
  • 1980-01-16 JP JP50024180A patent/JPS55501118A/ja active Pending
  • 1980-01-16 CH CH734580A patent/CH632354A5/fr not_active IP Right Cessation
  • 1980-01-16 WO PCT/FR1980/000005 patent/WO1980001523A1/fr active Application Filing
  • 1980-01-16 BE BE0/198991A patent/BE881183A/fr not_active IP Right Cessation
  • 1980-01-16 NL NL8020005A patent/NL8020005A/nl not_active Application Discontinuation
  • 1980-01-16 GB GB8027723A patent/GB2051483B/en not_active Expired
  • 1980-01-17 ES ES487808A patent/ES8101812A1/es not_active Expired
  • 1980-01-17 IT IT46803/80A patent/IT1136475B/it active
  • 1980-08-26 NO NO802529A patent/NO802529L/no unknown
  • 1980-09-11 SE SE8006361A patent/SE8006361L/ not_active Application Discontinuation

Patent Citations (5)

Also Published As

Similar Documents

Legal Events