JP5703928B2 - Key device - Google Patents

Description

  The present invention relates to a key device used for a keyboard of an electronic device.

  In general, the individual key devices arranged on the keyboard of an electronic device are configured such that, for example, on a printed circuit board, the comb-shaped input side contact to which a key sampling signal is applied and the comb-shaped output side contact are alternately spaced at regular intervals. The key contacts are combined so as to be adjacent to each other. A key member made of carbon rubber is pressed and brought into contact with the key contact on the substrate, whereby the input side contact and the output side contact are brought into conduction, and the key sampling signal is derived as a key input.

  However, when conductive foreign matter such as carbon rubber fragments or metal pieces enters the key contacts on the board and the input / output is short-circuited, the key input signal is derived without stopping from the output side contacts. Thus, the CPU that controls the electronic device enters a key lock state (freeze state).

  This is a conventional keyboard switch that has a structure in which the gap between the key and the key panel that communicates from the outside is sealed on a printed circuit board with key contacts. (See, for example, Patent Document 1).

JP-A-10-241493

  As in the conventional keyboard switch, sealing the gap with the outside leading to the printed circuit board having the key contacts has a problem that the structure becomes complicated and the manufacturing cost increases.

  In addition, it is possible to make it difficult for input / output short-circuiting due to conductive foreign matter, etc., by widening the distance between the input contact and output contact in the key contact. There is a problem that the conduction resistance between the two becomes high, resulting in a key input failure.

  The present invention has been made in view of such a problem, and maintains a proper distance between the input-side contact and the output-side contact of the key sampling signal, and the key when an electrical short occurs due to conductive foreign matter. It is an object of the present invention to provide a key device that can avoid a locked state.

  The key device according to the present invention has a key contact provided with an input-side contact and an output-side contact for a key sampling signal at a predetermined interval on a substrate. A key device in which the input-side contact and the output-side contact are brought into conduction when a conductive key member to be pressed comes into contact, and the key sampling signal is led to the output-side contact, The output side contacts of multiple systems provided at set intervals, the signal gates provided at the output terminals of the output side contacts of the multiple systems, and the AND output of the signal gates of the multiple systems are derived as key output signals. When a contact short circuit occurs between the output circuit to be connected and the input side contact and any one of the output side contacts of the plurality of systems, the output terminal is set based on the signal derived to the corresponding output side contact. It is characterized by comprising circuit means, the turning off the signal gate that is.

  According to the present invention, it is possible to avoid a key lock state when an electrical short occurs due to a conductive foreign object while maintaining an appropriate distance between the input side contact and the output side contact of the key sampling signal. Can be provided.

The circuit diagram which shows the structure of the key apparatus which concerns on embodiment of this invention. The timing chart which shows operation | movement of each part of the circuit which comprises the said key apparatus.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a circuit diagram showing a configuration of a key device according to an embodiment of the present invention.

  In the key device in the figure, for example, a circuit corresponding to one of a plurality of keys arranged in a matrix on a keyboard of a small electronic device is shown.

  This key device has a zigzag input side contact KS0 to which a key sampling signal KO (reference [periodic signal “Lo”] in this embodiment) is applied on a printed circuit board, and a zigzag shape of the input side contact KSO. A key contact KS including two comb-shaped output side contacts KS1 and KS2 adjacent to each other at a predetermined interval on one side and the other side is provided.

  A key member made of carbon rubber (not shown) is pressed against the key contact KS from above according to a user operation, and the input contact KS0 and the output contacts KS1 and KS2 are electrically connected by the key contact. The key sampling signal KO “Lo” is derived as two systems of key signals KI1 “Lo” and KI2 “Lo”.

  The two-system key signals KI1 and KI2 are always pulled-up and maintained at the “Hi” level when the key member is not pressed and the key member is not pressed.

  In addition, transfer gates G1 and G2 are provided at output ends of the key signals KI1 and KI2 derived from the two output side contacts KS1 and KS2, respectively, and the AND outputs of the transfer gates G1 and G2 are keyed. It is derived as an output signal KI and input to the CPU of the electronic device in which the key device is mounted.

  On the other hand, an electronic device on which the key device is mounted is provided with a reset IC (RIC).

  This reset IC (RIC) changes from “Lo” to “Hi” after a certain time (for example, 200 ms) after the system voltage V is activated when the power is turned on, or after a certain time after the reset switch SW is turned on. A reset signal RS that changes is output, and this reset signal RS is input to the CLR terminal and the CLK terminal of each of the first and second D flip-flops FF1 and FF2. Further, the CPU is also in the off state during the period when the reset signal RS is output. During this period, the key sampling signal KO is always “Lo” in all lines.

  The D signal of the first D flip-flop FF1 is supplied with a key signal KI1 from one of the output contacts KS1 of the two systems of output contacts KS1 and KS2. Similarly, the second D flip-flop The key signal KI2 from the other output side contact KS2 of the two output side contacts KS1 and KS2 is input to the D terminal of the FF2.

  The Q output of the first D flip-flop FF1 is input as an ON / OFF signal of the transfer gate G1, and similarly, the Q output of the second D flip-flop FF2 is also applied to the transfer gate G2. Input as ON / OFF signal.

  That is, each of the D flip-flops FF1 and FF2 latches the key signals KI1 and KI2 input to the D terminal in response to the rise of the reset signal RS from “Lo” to “Hi”, and outputs each gate from the Q output. In this case, the gates G1 and G2 are turned on when the latched key signals KI1 and KI2 are at "Hi" level, and are turned off when they are at "Lo" level.

  Therefore, in the normal state where the transfer gates G1 and G2 are ON, when the key signals KI1 and KI2 are maintained at the “Hi” level due to no key input, the key signals KI1 and KI2 at the “Hi” level remain as keys. The output signal KI is output to the CPU and the key not input (Key out) is recognized.

  Further, when the key is pressed (input), the input side contact KS0 of the key contact KS and the output side contacts KS1 and KS2 become conductive, and the key signals KI1 and KI2 are pulled to the periodic “Lo” level of the key sampling signal KO. Then, the “Lo” level key signals KI1 and KI2 are directly output to the CPU as the key output signal KI to recognize the key input (Key in).

  Next, the operation of the key device having the above configuration will be described.

  FIG. 2 is a timing chart showing the operation of each part of the circuit constituting the key device.

(Normal operation)
When the power source of the electronic device on which this key device is mounted is activated (ON), the two output side contacts KS1 and KS2 of the key contact KS are pulled up immediately, and the key signals KI1 and KI2 are “Hi”. Set to level.

  Further, after a predetermined time T1 from the power ON, the reset signal RS output from the reset IC (RIC) to the CLR terminal and the CLK terminal of the first and second D flip-flops FF1 and FF2 is changed from “Lo” to “Hi”. Accordingly, the key signals KI1 and KI2 of the two output side contacts KS1 and KS2 pulled up to the “Hi” level are latched at the D terminals of the D flip-flops FF1 and FF2. . Then, the Q outputs of the D flip-flops FF1 and FF2 become “Hi”, and the transfer gates G1 and G2 at the output terminals of the output side contacts KS1 and KS2 are turned on.

  Further, the CPU is turned on at the timing T1 ′ after the reset signal RS rises to the “Hi” level, and starts the control operation. The key sampling signal KO changes to a periodic signal for sampling the key matrix in accordance with the operation of the CPU. The hatched portion in the figure indicates a period during which the sampling signal “Lo” is periodically output in a pulse shape.

  When no key is input, the key signals KI1 and KI2 of the two output side contacts KS1 and KS2 at the key contact KS are maintained at the “Hi” level that is pulled up. A "Hi" level key output signal KI is output to the CPU via the gates G1 and G2, and is recognized as no key input (Key out).

  Thereafter, when key input is performed by pressing a key in accordance with a user operation, the input side contact KS0 at the key contact KS and the two output side contacts KS1 and KS2 become conductive, and the key sampling signal KO " Lo ”is derived as key signals KI1 (“ A ”in the figure) and KI2 (“ B ”in the figure). Then, a “Lo” level key output signal KI (“C” in the figure) is output to the CPU via the transfer gates G1 and G2, and is recognized as a key input (Key in).

  Thereafter, when the key is returned to the key-out state according to the user operation, the key signals KI1, KI2 of the output side contacts KS1, KS2 at the key contact KS are at the “Hi” level corresponding to the pull-up. Return to. Then, the “Hi” level key output signal KI is output to the CPU via the transfer gates G1 and G2, and is recognized as a key not input (Key out).

  In this way, in normal operation, the key sampling signal KO “Lo” corresponding to the key input (Key in) and the Pull-up signal “Hi” corresponding to the key not input (Key out) are either Is also derived as a key output signal KI via the two output contacts KS1 and KS2 and the corresponding transfer gates G1 and G2, and is recognized by the CPU as key input (Key in) and key non-input (Key out).

(Contact short-circuit occurrence operation)
When conductive foreign matter enters the key contact KS of the printed circuit board and a contact short (KS1 short) occurs between the input side contact KS0 and one output side contact KS1 due to the foreign matter, for example, one key signal KI1 In this case, the key sampling signal KO “Lo” is continuously derived (“Ashort” in the figure), and the same key output signal KI as the key input (Key in) state is derived via one transfer gate G1. ("Cshort" in the figure).

  In this case, regardless of whether the key member is pressed / returned, the CPU enters a key lock state (freeze state) erroneously recognized as a key input (Key in).

(Contact short-circuit return operation)
In response to the electronic device being in the key lock state (freeze state) due to the contact short (KS1 short), the reset switch SW is turned ON (Reset) by the user operation, or the power supply is restarted (ON → When turned OFF → ON), the key sampling signal KO becomes “Lo” for a certain time in all lines, and in response to the rising “Hi” of the reset signal RS after a certain time T2, the first D flip-flop FF1 The key signal KI1 “Lo” during the occurrence of a short circuit (“Ashort” in the figure) is latched, and the transfer gate G1 is maintained OFF from the reset (Reset).

  As a result, the key signal KI1 “Lo” of one output side contact KS1 during the occurrence of a short circuit (“Ashort” in the figure) is blocked by the transfer gate G1, and is no longer derived as the key output signal KI.

  On the other hand, the pull-up key signal KI2 “Hi” at the other output side contact KS2 in the normal state is latched in the second D flip-flop FF2, and the transfer gate G2 is turned on.

  As a result, in a state where no key is input after the reset (Reset), only the key signal KI2 “Hi” of the normal output side contact KS2 at the key contact KS is derived as the key output signal KI via the transfer gate G2, Recognized as key out.

  Therefore, each time there is a key input (Key in (1) (2)...), The key signal KI2 “Lo” of the normal output side contact KS2 from which the key sampling signal KO “Lo” has been derived each time. Only “(B1, B2,... In the figure) is derived as a key output signal KI (C1, C2,... In the figure) through the transfer gate G2 and recognized as a key input (Key in).

  Therefore, according to the key device having the above-described configuration, the key contact KS on the printed circuit board is connected to the two output side contacts KS1, KS2 at regular intervals on both sides along the input side contact KS0 to which the key sampling signal KO is applied. The transfer gates G1 and G2 are provided at the output ends of the output side contacts KS1 and KS2, and the AND output of the transfer gates G1 and G2 is derived as the key output signal KI. When the key signals KI1 and KI2 of the output contacts KS1 and KS2 are latched in response to power ON or reset, and the key signals KI1 / KI2 of the output contacts KS1 / KS2 in which the contact short circuit occurs are latched, When the transfer gate G1 / G2 to be turned off is turned off and the key signal KI1 / KI2 of the normal output side contact KS1 / KS2 is latched, D flip-flops FF1, FF2 are provided to turn on the corresponding transfer gate G1 / G2.

  For this reason, the entry of conductive foreign matter onto the key contact KS causes a contact short between one of the two output contacts KS1, KS2 and the input contact KS0, and the key lock state (freeze state). In this case, the transfer gate G1 / G2 from the output side contact KS1 / KS2 that is in the short-circuit state is turned off (cut off) by restarting the power supply or resetting, and the normal output side contact KS1 / KS2 The key output signal KI can be derived only through the transfer gate G1 / G2.

  Therefore, it is possible to easily avoid a key lock state when an electrical short occurs due to conductive foreign matter while maintaining an appropriate distance between the input side contact KS0 and the output side contact KS1 / KS2 of the key sampling signal KO. Is possible.

  In the above embodiment, when a contact short between the input side contact KS0 and the output side contact KS1 or KS2 occurs in the key contact KS, and the electronic device is in a key lock state (freeze state), it is reset by a user operation. When the switch SW is turned ON (Reset) or the power supply is restarted (ON → OFF → ON), the key signal KI1 (KI2) of the output side contact KS1 (KS2) where the contact short-circuit has occurred is D flip-flop Latched by FF1 (FF2), the transfer gate G1 (G2) of the corresponding key signal KI1 (KI2) is turned OFF to avoid the key lock state.

  On the other hand, when the CPU recognizes that the key sampling signal KO has been continuously derived as the key output signal KI for a preset time or more, it is determined that a contact short-circuit has occurred, and each D flip-flop By forcing the reset signal RS to FF1 (FF2) and latching the D terminal, the transfer gate G1 (G2) of the output side contact KS1 (KS2) where the contact short-circuit occurs is turned off (cut off) in real time. The key lock state may be avoided.

  In the above embodiment, the Q output of the D flip-flop FF1 (FF2) is latched to “Lo” in order to turn off the transfer gate G1 (G2) of the output side contact KS1 (KS2) in which the contact short has occurred. Is done. Therefore, by reading the latch operation of the Q output to “Lo” in the D flip-flop FF1 (FF2) by the CPU, it is possible to recognize which of the keys arranged in a matrix has a contact short circuit. become.

  Further, in the circuit of the key device shown in FIG. 1 of the above embodiment, the D flip-flops FF1 and FF2 and transfer gates surrounded by the broken line X provided corresponding to the two systems of the output side contacts KS1 and KS2. The circuit composed of G1 and G2 may be built in the CPU.

  In the above embodiment, the output contacts KS1 and KS2 of the key contact KS have two systems, and the corresponding transfer gates G1 and G2 and D flip-flops FF1 and FF2 are provided. It is good also as a structure which makes it easy to avoid generation | occurrence | production of a contact short circuit by making a subsequent circuit into 3 or more systems.

  Note that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention at the stage of implementation. Further, each of the embodiments includes inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, even if some constituent elements are deleted from all the constituent elements shown in each embodiment or some constituent elements are combined in different forms, the problems described in the column of the problem to be solved by the invention If the effects described in the column “Effects of the Invention” can be obtained, a configuration in which these constituent requirements are deleted or combined can be extracted as an invention.

  Hereinafter, the invention described in the scope of claims of the present application will be appended.

[1]
A conductive key member having a key contact provided with an input-side contact and an output-side contact for a key sampling signal at a predetermined interval on a substrate, and pressed to the key contact in response to a user operation Is a key device in which the input side contact and the output side contact are brought into conduction by contacting and the key sampling signal is derived to the output side contact,
A plurality of output-side contacts provided at predetermined intervals with the input-side contacts;
A signal gate provided at the output end of each of the multiple-side output side contacts,
An output circuit for deriving the AND output of the multiple signal gates as a key output signal;
The signal gate provided at the output terminal based on the signal derived to the corresponding output side contact when a contact short occurs between the input side contact and any output side contact of the plurality of systems Circuit means for turning off,
A key device comprising:

[2]
In the case where a contact short occurs between the input-side contact and any output-side contact among the plurality of systems, the circuit means outputs a signal derived to the corresponding output-side contact according to a user operation. Based on the signal gate provided at its output,
The key device according to [1], which is characterized in that

[3]
In the case where a contact short occurs between the input-side contact and any output-side contact among the plurality of systems, the circuit means has a time over which the key sampling signal is set in advance for the corresponding output-side contact. The signal provided at the output terminal based on the derived key sampling signal when the determination unit determines that the key sampling signal is continuously derived. Turn off the gate,
The key device according to [1], which is characterized in that

[4]
The circuit means corresponds to a restart signal or a reset signal corresponding to a user operation when a contact short occurs between the input side contact and any output side contact of the plurality of systems. A D flip-flop that latches a signal derived to the output side contact at the D terminal and turns off the signal gate provided at the output end of the output side contact by the latched Q output;
The key device according to [1], which is characterized in that

KS: Key contact KS0: Input side contact KS1, KS2: Output side contact (2 lines)
G1, G2 ... Transfer gate (2 lines)
SW: Reset switch RIC: Reset IC
FF1, FF2 ... D flip-flop (2 systems)
K0 ... Key sampling signal KI1, KI2 ... Key signal (2 lines)
KI: Key output signal RS: Reset signal

Claims (4)

A conductive key member having a key contact provided with an input-side contact and an output-side contact for a key sampling signal at a predetermined interval on a substrate, and pressed to the key contact in response to a user operation Is a key device in which the input side contact and the output side contact are brought into conduction by contacting and the key sampling signal is derived to the output side contact,
A plurality of output-side contacts provided at predetermined intervals with the input-side contacts;
A signal gate provided at the output end of each of the multiple-side output side contacts,
An output circuit for deriving the AND output of the multiple signal gates as a key output signal;
The signal gate provided at the output terminal based on the signal derived to the corresponding output side contact when a contact short occurs between the input side contact and any output side contact of the plurality of systems Circuit means for turning off,
A key device comprising: In the case where a contact short occurs between the input-side contact and any output-side contact among the plurality of systems, the circuit means outputs a signal derived to the corresponding output-side contact according to a user operation. Based on the signal gate provided at its output,
The key device according to claim 1. In the case where a contact short occurs between the input-side contact and any output-side contact among the plurality of systems, the circuit means has a time over which the key sampling signal is set in advance for the corresponding output-side contact. The signal provided at the output terminal based on the derived key sampling signal when the determination unit determines that the key sampling signal is continuously derived. Turn off the gate,
The key device according to claim 1. The circuit means corresponds to a restart signal or a reset signal corresponding to a user operation when a contact short occurs between the input side contact and any output side contact of the plurality of systems. A D flip-flop that latches a signal derived to the output side contact at the D terminal and turns off the signal gate provided at the output end of the output side contact by the latched Q output;
The key device according to claim 1.

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