JP2007122245A - Keyboard unit and keyboard degradation detection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize preventive maintenance of a keyboard by determining in advance a condition unable to transmit key code data caused by a key switch trouble. <P>SOLUTION: Key switch conditions on a key matrix (3) are detected for every scanning output signal (2) transmitted from a microprocessor (1). A sense signal (4) is reversed and transmitted to the microprocessor (1) at the key input. The key code data is transmitted to a host computer (8). In this case, after amplifying decreased voltage caused by contact resistance of the key switch generating on the sense signal (4) by an amplifier (5), the output to the microprocessor (1) is reversed when comparing with reference voltage set up with a comparator (6) by assuming a replacement period and detecting a value exceeding the reference voltage, and the microprocessor (1) reports it to the host computer (8). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a keyboard device having a function of detecting and notifying when a keyboard is replaced.

  Recently, an increasing number of keyboard contacts are using membrane sheets instead of mechanical contacts to reduce costs. However, the reliability of the membrane contact is inferior to that of a mechanical contact and generally has a short life. There is a growing need for risk avoidance through notification of replacement timing.

  Incidentally, an inspection method for measuring a key switch contact resistance of a keyboard and detecting a defect during production is disclosed in Patent Document 1 below. More specifically, the keyboard contact group (keyboard matrix) is all turned on by a predetermined method, the connection with the horizontal terminal row of the keyboard matrix is fixed, and the vertical terminal row is sequentially switched. A constant current flows at each switching, and the voltage effect can be detected. A contact having a voltage effect larger than a predetermined value has a large contact resistance value, so that a keyboard key switch failure can be detected.

JP-A-63-71715

  The keyboard in the information processing terminal is an important device responsible for its basic functions. However, depending on the usage conditions, contact failure due to dust or oily smoke entering. Contact failure due to deterioration of the conductive material or increase in conductive pattern resistance. In many cases, the basic functions cannot be performed. In particular, when used in a business terminal, a sudden failure of the keyboard causes a great loss of business, and the realization of preventive maintenance by prior notification of replacement time has been an important issue.

  The above-described conventional technique (the invention described in Japanese Patent Laid-Open No. 63-71715) is used for inspecting whether there is a defect before product shipment. Of course, if the voltage drop based solely on the contact resistance value is higher than the specified voltage, it is determined that the product is defective.However, since it is not assumed that the replacement time of the keyboard after product shipment is determined, the replacement time of the keyboard It does not have a function to notify the operator.

  In other words, the above-mentioned prior art does not assume the inspection from the start of use of the keyboard until the occurrence of a defect for the purpose of keyboard inspection before product shipment, so it is not possible to notify the keyboard operator of the replacement time, and the product If the keyboard cannot be inspected after shipment, and the keyboard becomes defective and cannot be used within the working hours, the work will be hindered.

  Accordingly, an object of the present invention is to provide a keyboard device that can determine in advance a state in which key code data cannot be transmitted due to a key switch failure or the like, and realize preventive maintenance of the keyboard. In other words, it is possible to determine the life of the key switch every time the user inputs a key during daily work on the device in operation and notify the replacement time for preventive maintenance, thereby realizing preventive maintenance of the keyboard. There is to plan.

  In order to solve the above problems, the present invention employs means for solving the problems having the following characteristics.

  An aspect of a keyboard device according to the present invention is a key matrix unit composed of a plurality of movable contacts arranged in a matrix, a scan signal is output to the key matrix unit, and an inverted sense signal is input corresponding to the key input. A comparator that receives the scan signal, receives a sense signal output from the key matrix unit, and compares the output voltage of the key matrix unit with a reference voltage. After a lapse of time, when the key switch contact resistance value exceeds a predetermined threshold at the time of key input, and the output voltage of the key matrix portion exceeds the reference voltage, a comparison output signal is sent to the microprocessor, The microprocessor receives the comparison output signal and outputs a keyboard failure control signal to a host computer. And features.

  An aspect of a keyboard deterioration detection method according to the present invention includes: a step of outputting a scan signal to a key matrix portion composed of a plurality of movable contacts arranged in a matrix; and the key corresponding to a key input in response to the scan signal. A step of inputting a sense signal output from the matrix unit, a step of comparing a voltage of the input sense signal with a reference voltage, and a contact resistance value of a key switch contact at a key input after a predetermined time has elapsed And when the voltage of the sense signal exceeds the reference voltage, a step of sending a comparison output signal to the microprocessor and a step of receiving the comparison output signal and outputting a keyboard failure control signal to the host computer It is characterized by having.

  The preventive maintenance function of the keyboard according to the present invention detects the contact resistance of the key switch contact at the time of key input and determines that it is almost time to replace the keyboard when the resistance value exceeds the threshold value. Has a function of making a notification prompting.

  Therefore, by using the present invention, the key switch contact failure due to the ingress of dust or oily smoke, the input failure due to the increase of contact resistance or conductive pattern resistance due to deterioration of the conductive material, etc., and the basic function of key code data transmission is achieved. Even if you can't do it, preventive maintenance of the keyboard can be realized with the advance notification function.

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

  Referring to FIG. 2, the keyboard device of the present invention includes a microprocessor (1) having a preventive maintenance function, a key matrix (10), an amplifier (5), a comparator (6), a reference power supply (7), an LED (11). ).

  The microprocessor (1) is connected to the scan signal (2) KS1, KS2, KS3,..., KSn of the key matrix (3) and the sense signal (4) KR1, KR2, KR3,. The key switch (12) is waiting to be pressed. When the key switch (12) is pressed and the scan signal (2) is turned on, the sense signal (4) is driven from the VCC (13) through the pull-up resistor (14). The sense signal is amplified by an amplifier (5), and a logic output obtained by comparing the output voltage from the amplifier with a reference voltage from a reference power supply (7) is input to the microprocessor (1) by a comparator (6). The microprocessor (1) to which the signal is inputted may send a control signal to the host computer (8) or blink the LED (11) according to the signal state.

  FIG. 3 shows in detail the configuration of a detection circuit that detects the sense signal (4) as the output of the key matrix of FIGS.

  In FIG. 3, when the key switch (12) is pressed, the sense signal (4) pulled up by the power supply VCC (13) and the pull-up resistor Rp is output via the contact resistance Rc (16). The sense signal (4) is input to the non-inverting input of the amplifier (5), and the logic output of the amplifier (5) is connected to the inverting input of the comparator (6). The reference voltage of the comparator (6) is obtained by dividing the reference power source (7) by the setting resistor Rs1 (18) and the setting resistor Rs2 (19), and a comparison signal is output from the comparator (6). . The comparison signal is sent to the microprocessor (1).

  Next, the operation of the contact resistance detection circuit of FIGS. 2 and 3 will be described with reference to the time charts of FIGS.

  The microprocessor (1) turns on the sense signal (4) KR1, KR2, KR3,... While the scan signal (2) of the key matrix (3) is sequentially turned on with KS1, KS2, KS3,. , KSn is monitored and waiting for the operator to press the key switch (12). When key input is performed by the operator, the sense signal (4) pulled up by the power supply VCC (13) and the pull-up resistor Rp is output. The basic operation of transmitting the key code of the microprocessor (1) is performed by the output of the sense signal (4), and the voltage drop is detected by the key switch (12) contact resistance Rc (16) on the sense signal (4). .

  Here, the operation of the detection circuit in the initial state of the keyboard is shown in FIG. 4 as a time chart. As shown in FIG. 4, when the key switch (12) is turned on, the pull-up resistor Rp (14) and the contact resistance Rc (of the key switch (12) from the power supply VCC (13) each time the scan signal (2) is turned on. 16), the voltage divided by the ON resistance of the output circuit of the microprocessor (1) is amplified by the amplifier (5) and output to the comparator (6).

  The comparator (6) compares the reference voltage, which is a predetermined threshold set by the setting resistor Rs1 (18) and the setting resistor Rs2 (19), with the amplifier output voltage amplified by the amplifier (5), and If the amplifier output voltage is equal to or higher than the reference voltage, it is determined that the keyboard is in a degraded state and needs to be replaced, and an inverted logic output (L level) is sent to the microprocessor (1).

  By the way, while the key switch (12) is turned on, the detected voltage is not stabilized due to the parasitic capacitance of the amplifier (5), and the output of the amplifier does not immediately become lower than the reference voltage. Although the output continues to be sent (the portion on the left side of the confirmation arrow in the amplifier output in FIG. 4), when the key input is confirmed, the parasitic capacitance is discharged and the state is stabilized. That is, the microprocessor (1) detects the input from the comparator (6) at the timing when the key input is confirmed, but in this case, the logic output from the comparator (6) is not inverted, The keyboard is judged to be normal while maintaining the H level. Compared with the amplifier output of FIG. 5 described below, the decrease in FIG. 4 is more severe because the time constant RC is small.

  Next, the operation of the detection circuit when the keyboard is approaching the time for replacement is shown in FIG. 5 as a time chart. When the keyboard is approaching the time for replacement, as shown in the time chart of FIG. 5, unlike the initial state, the contact resistance (Rc) of the key switch (12) is increased, so the key input is confirmed. The output voltage of the amplifier (5) does not become lower than the reference voltage even when the timing is reached, and the logic output of the comparator (6) changes every time the scan signal (2) is turned ON (when the scan signal becomes L level). Ii) Continue to output inverted logic output (L level). The microprocessor (1) detects this inverted logic output and determines that it is time to replace it.

  As soon as the replacement time is determined, a control signal is sent to the host computer (8) to notify the user of the preventive replacement of the keyboard. As a notification method, the function can be easily realized without adding a new special command or the like by using a method closed in the keyboard such as blinking the LED (11) on the keyboard.

  Further, each of the above-described embodiments is merely an example of a preferred embodiment of the present invention, and the present invention can be implemented with various modifications without departing from the gist thereof. For example, in the above embodiment, the input section of the comparator (6) for inputting the amplifier output is an inverting input terminal, but it may be a non-inverting input terminal. In that case, a logic output corresponding to the comparator is output.

  The present invention is highly effective because it is possible to know in advance the replacement time of the keyboard and to avoid the loss in the field of business terminals where a great loss occurs such as a business interruption due to a keyboard failure.

It is the block diagram which showed the structure of the keyboard apparatus based on this invention connected to a host computer. It is the block diagram which showed more concretely the structure of the keyboard apparatus based on this invention connected to a host computer. It is the figure which showed more concretely the structure of the contact resistance detection circuit of the keyboard apparatus which concerns on this invention. It is the time chart figure which showed the operation of the keyboard device which relates to this invention in the initial state. It is a time chart figure which showed operation of a keyboard device concerning the present invention at the time of exchange time detection.

Explanation of symbols

1 Microprocessor 2 Scan signal 3 Key matrix 4 Sense signal 5 Amplifier 6 Comparator 7 Reference power supply 8 Host computer 9 Keyboard 11 LED
12 Key switch 13 Power supply (VCC)
14 Pull-up resistance 16 Contact resistance 18, 19 Setting resistance

Claims (7)

In a keyboard device having a key matrix portion composed of a plurality of movable contacts arranged in a matrix and a microprocessor for outputting a scan signal to the key matrix portion and inputting an inverted sense signal corresponding to the key input ,
A comparator that receives the scan signal, receives a sense signal output from the key matrix unit, and compares the output voltage of the key matrix unit with a reference voltage;
The comparison unit compares with the microprocessor when the contact resistance value of the key switch contact exceeds a predetermined threshold at the time of key input after a predetermined time elapses and the output voltage of the key matrix unit exceeds the reference voltage. Send output signal,
The keyboard device, wherein the microprocessor receives the comparison output signal and outputs a keyboard failure control signal to a host computer. The comparison unit includes an amplifier and a comparator,
The non-inverting input unit of the amplifier is connected to a pull-up resistor of a power supply unit that pulls up the sense signal and a contact resistance of a key switch,
One input part of the comparator is connected to the output part of the amplifier, and the other input part is connected to a reference power supply part for dividing and setting the reference voltage by a first setting resistor and a second setting resistor. And
A comparison output signal is sent to the microprocessor when a voltage drop due to an increase in the contact resistance value increases after a predetermined time and the output voltage of the amplifier exceeds the reference voltage. Item 2. The keyboard device according to Item 1.   3. The comparator according to claim 2, wherein one input section of the comparator is an inverting input terminal, and an inverting output signal is sent to the microprocessor when the output voltage of the amplifier exceeds the reference voltage. Keyboard device.   4. The keyboard device according to claim 3, wherein the microprocessor receives the inverted output signal and blinks an LED on the keyboard. Outputting a scan signal to a key matrix portion composed of a plurality of movable contacts arranged in a matrix;
Receiving the scan signal and inputting a sense signal output from the key matrix unit in response to a key input;
Comparing a voltage of the input sense signal with a reference voltage;
After a predetermined time has elapsed, when a key switch contact contact resistance value exceeds a predetermined threshold at the time of key input, and when the voltage of the sense signal exceeds the reference voltage, sending a comparison output signal to the microprocessor;
Receiving the comparison output signal, and outputting a keyboard failure control signal to a host computer. In the comparison step,
After the step of inputting the sense signal, the sense signal output from the key matrix unit is amplified, the voltage of the amplified sense signal is compared with the reference voltage,
After a predetermined time has elapsed, a voltage drop due to the increase in the contact resistance value becomes large, and when the amplified sense signal voltage exceeds the reference voltage, a comparison output signal is sent to the microprocessor. The keyboard deterioration detection method according to claim 5.   7. The keyboard deterioration detecting method according to claim 6, wherein the reference voltage is a voltage divided by a first setting resistor and a second setting resistor.

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