JP2012098865A - Input device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an input device capable of reducing power consumption when a key switch is in an on state.SOLUTION: When any key switch is not in an on state in a low power consumption state of a microcomputer 2, an interruption terminal (b) is connected to a ground potential via a pull-down resistance element R6. When any key switch is changed to an on state, the microcomputer 2 changes its state from the low power consumption state to a normal state by inputting a high-level interruption signal to the interruption terminal (b). The microcomputer 2 can determine the key switch in the on state on the basis of a voltage value input to a key input terminal (a) by outputting a low-level signal from the interruption terminal (b) to one terminal of each key switch so as to change the voltage value input to the key input terminal (a) according to the key switch in the on state.

Description

  The present invention relates to an input device, and more particularly to an input device having a low power consumption state in which a control means stops operating in a standby state.

  An electronic device such as an AV device supplies power only to a microcomputer (hereinafter simply referred to as a microcomputer) and its peripheral circuits so that the power can be turned on in response to a user key operation or remote control operation even when the power is turned off. State (ie, standby state). However, recently, even in the standby state, further power saving is required, and the microcomputer is provided with a low power consumption state in which the operation of the microcomputer is stopped when there is no processing executed by the microcomputer. When a key operation is performed by the user, an interrupt signal is input to the interrupt terminal of the microcomputer to shift from the low power consumption state to the normal state (Patent Documents 1 and 2). In Patent Document 1, it is necessary to provide a general-purpose input terminal corresponding to the OR circuit and each key switch, and the circuit configuration is complicated. In Patent Document 2, each key of the key matrix is repeatedly scanned to obtain a key matrix. Although valid key input is detected, the scan signal causes noise, so it is not practical particularly in AV equipment.

  On the other hand, a circuit 501 shown in FIG. 5 of Patent Document 4 has been proposed as a circuit that allows a microcomputer to determine which one of a plurality of key switches connected in parallel is turned on by only one key input terminal a. In the circuit 501, for example, when the key switch S2 is turned on, a voltage of V1 × R2 / (R1 + R2) is input to the key input terminal a of the microcomputer 2. The input voltage is A / D converted, compared with voltage values corresponding to predetermined key switches S1 to S5, and the microcomputer 2 determines that the key switch S2 has been pressed.

  In this circuit 501, when the microcomputer is provided with a low power consumption state, a comparator 505 is required to shift from the low power consumption state to the normal state. The voltage at point A is input to one end of the comparator 505 and the reference voltage is input to the other end. When the key switch is turned on, the comparator sends an interrupt signal (low level voltage) to the interrupt terminal b. To give. However, the circuit 501 has a problem in that the cost increases because it is necessary to provide a comparator to cancel the low power consumption state. In order to solve this problem, Patent Document 3 proposes a method of intermittently operating a microcomputer by a built-in timer function during standby, periodically operating an A / D converter, and determining a key switch that is turned on. Yes. However, in this method, although it is not necessary to use a comparator, there is a problem that power consumption during standby cannot be sufficiently reduced because the microcomputer is intermittently operated during standby.

  In order to solve this problem, the present applicant has proposed an input device described in FIG. 1 and FIG. The input device includes an input unit having a plurality of key switches connected in parallel, a key input terminal to which one end of the input unit is connected, and a control unit having an interrupt terminal to which the other end of the input unit is connected. Prepare. When the key switch is turned on, the control means shifts from the low power consumption state to the normal state by inputting an interrupt signal from the other end of the input means to the interrupt terminal. And a control means judges the switch turned on based on the voltage value given to a key input terminal from the one end of an input means.

  However, this input device has a problem in that power consumption increases because a large current continues to flow from the power source V1 to the ground potential through the key switch that is turned on while the key switch is turned on. There is. Further, as shown in FIG. 4 of Patent Document 4, when the number of key switches is increased by connecting a plurality of input means 31 and 32 in parallel, an AND circuit 404 is separately required, which increases costs. There is a problem of doing.

JP-A-9-198169 JP-A-7-13671 JP 2001-186657 A JP 2005-266843 A

  An object of the present invention relates to an input device that determines a key switch that is turned on based on a voltage value input to a key input terminal of a control means, and an input that can reduce power consumption when the key switch is turned on. Is to provide a device.

  An input device according to a preferred embodiment of the present invention includes an input means including a resistance element and a key switch having one terminal connected to the resistance element and having a plurality of voltage determination circuits connected in series with each other; A control means having a key input terminal to which one terminal of the key switch included in the voltage determination circuit in the foremost stage is connected, and an interrupt terminal; the other terminal of each key switch is connected to the interrupt terminal And when the control means is in a low power consumption state and none of the key switches is turned on, the interrupt terminal causes the pull-down resistor element to be connected to the ground potential via the pull-down resistor element. By connecting to the ground potential via the key switch, a low level signal is input to the interrupt terminal. When this is turned on, a high-level interrupt signal is input to the interrupt terminal, thereby shifting from the low power consumption state to the normal state, and the control means changes from the low power consumption state to the normal state. When transitioned, by outputting a low level signal from the interrupt terminal to the other terminal of each key switch, the voltage value input to the key input terminal changes according to the key switch turned on, A key switch that is turned on is determined based on a voltage value input to the key input terminal.

  When any of the key switches is turned on, a current is supplied to the ground potential via the key switch and the pull-down resistor element that are turned on until the control means shifts from the low power consumption state to the normal state. Flowing. Here, by setting the resistance value of the pull-down resistor element to be large, the flowing current can be reduced and the power consumption can be reduced. On the other hand, when the control means shifts from the low power consumption state to the normal state, a low level signal is output from the interrupt terminal to the other terminal of the key switch. A voltage determined according to the key switch in the state can be input to the key input terminal.

  In a preferred embodiment, after the control means determines a key switch that is turned on based on a voltage value input to the key input terminal, a low level is transmitted from the interrupt terminal to the other terminal of each key switch. Stops outputting the signal.

  Therefore, after determining the key switch that is turned on based on the voltage value input to the key input terminal, a current flows to the ground potential through the key switch that is turned on and the pull-down resistor element. Here, by setting the resistance value of the pull-down resistor element to be large, the flowing current can be reduced and the power consumption can be reduced.

  In a preferred embodiment, a plurality of the input means are provided in parallel, the control means has the key input terminal for each of the input means, and the voltage determination circuit at the foremost stage of the plurality of input means includes Including one terminal of the key switch connected to the corresponding key input terminal of the control means, the other terminal of each key switch of the plurality of input means connected to the interrupt terminal, and the pull-down resistor element It is connected to the ground potential via.

  With this configuration, it is possible to provide a plurality of input means connected in parallel without providing an AND circuit as in Patent Document 4. It is possible to deal with a large number of key inputs at low cost by using a plurality of parallel circuits.

  To provide an input device capable of reducing power consumption when a key switch is in an on state with respect to an input device that determines a key switch that is turned on based on a voltage value input to a key input terminal of a control means. it can.

It is a circuit block diagram which shows the input device 1 by preferable embodiment of this invention. It is a flowchart which shows the process of the microcomputer 2 of the input device 1. FIG. 6 is a circuit block diagram showing an input device 101 according to another preferred embodiment of the present invention.

  Hereinafter, preferred embodiments of the present invention will be specifically described with reference to the drawings. However, the present invention is not limited to these embodiments. FIG. 1 is a schematic circuit diagram showing an input device 1 according to a preferred embodiment of the present invention. The input device 1 is a circuit that determines a key switch that is turned on by A / D converting a voltage input to a microcomputer, and includes a control unit 2 and an input unit 3. A device to which the input device 1 can be applied has a standby state in which a power supply voltage is supplied only to the microcomputer so that the power can be turned on by a user's key input operation.

  The control means 2 is for controlling the operation of an electronic device (for example, a CD player or the like) to which the input device 1 of the present embodiment can be applied, and is generally a microcomputer (hereinafter simply referred to as a microcomputer). Can be employed. The microcomputer 2 is connected to a memory 4 (ROM and / or RAM, etc.) via a bus or the like, and executes various programs (for example, a CD player) by executing various programs stored in the memory 4. Control). The microcomputer 2 has a normal state and a low power consumption state as its operation state. The normal state is generally a state in which the microcomputer 2 can execute an operation. The low power consumption state is a state in which the power consumption is further reduced by the microcomputer 2 stopping its operation (for example, clock oscillation and clock supply) when the entire device is in the standby state.

  The microcomputer 2 has a key input terminal a and an interrupt terminal b. The key input terminal a is a terminal to which a voltage for determining the key switch that is turned on is input. A voltage is input from the input means 3 to the key input terminal a, and when any of the key switches is turned on, the input voltage value changes (a predetermined voltage corresponding to the turned on key switch). Less voltage). The microcomputer 2 performs A / D (analog / digital) conversion on the voltage input to the key input terminal a, and compares the voltage with a predetermined voltage value corresponding to each key switch. Determine the switch. The interrupt terminal b is a terminal to which an interrupt signal for shifting from the low power consumption state to the normal state is input from the input unit 3.

  The input means 3 gives an instruction to the microcomputer 2 in response to an ON operation of the key switch by the user. The input means 3 has a plurality of voltage determination circuits 5a to 5e connected in series with each other. Each of the voltage determination circuits includes a resistance element and a key switch having one terminal connected to the resistance element, and determines a voltage value to be applied to the key input terminal a when the key switch is turned on. Note that any appropriate number of key switches (that is, voltage determination circuits) can be adopted depending on the function and operation required for the device, but in the present embodiment, five key switches SW1 to SW5 are provided. It has been. The voltage determination circuit 5a (referred to as a first voltage determination circuit) has a resistance element R1 and a key switch SW1 connected to the resistance element R1, and the resistance element R1 is connected to a power source V1. Here, the voltage determination circuit 5a is the voltage determination circuit in the forefront stage. The voltage determination circuit 5b has a resistance element R2 and a key switch SW2, the voltage determination circuit 5c has a resistance element R3 and a key switch SW3, and the voltage determination circuit 5d has a resistance element R4 and a key switch SW4. The voltage determination circuit 5e includes a resistance element R5 and a key switch SW5. Here, the voltage determination circuit 5e is the last-stage voltage determination circuit. The resistance elements R1 to R5 are connected in series from the power source V1, and the other terminals of the key switches SW1 to SW5 are connected to the ground potential via the pull-down resistance element R6.

  The input means 3 gives a signal for determining which key switch is turned on from one end A to the key input terminal a. That is, one end A of the input means 3 is connected to the key input terminal a of the microcomputer 2. One end A of the input means 3 has a predetermined voltage (power supply voltage V1) when the key switches are not turned on (that is, all the key switches are turned off), and when one of the key switches is turned on, This is a node having a voltage lower than a predetermined voltage V1 corresponding to the key switch that is turned on. That is, one end A of the input means 3 is a node to which a key switch SW1 provided at a position electrically closest to the power source V1 among the plurality of key switches SW1 to SW5 is connected. In other words, one end A of the input means 3 is the foremost stage, and is a connection end between the resistor element R1 and the key switch SW1 included in the first voltage determination circuit 5a directly connected to the power source V1.

  Further, when the key switch is turned on, the input means 3 gives an interrupt signal from the other terminal of each key switch SW1 to SW5 to the interrupt terminal b. That is, the other terminals of the key switches SW1 to SW5 are connected to the interrupt terminal b of the microcomputer 2. The interrupt signal is a high level voltage. That is, a high level (that is, a voltage higher than a predetermined voltage) and a low level voltage (ground potential) are applied to the interrupt terminal b, and the microcomputer 2 detects the high level voltage as an interrupt signal.

  When the key switch is not turned on (that is, all the key switches are turned off), the voltage of the other terminal of each key switch SW1 to SW5 becomes the ground potential (that is, low level), and the interrupt signal is sent to the interrupt terminal b. It will be in a state not given. Therefore, the microcomputer 2 maintains a low power consumption state. On the other hand, when any one of the key switches is turned on, the voltage at the other terminal of each of the key switches SW1 to SW5 is changed from the power supply voltage V1 to the resistors R1 and R6 (and the resistors R2 to R5 according to the turned on key switch). ), And the interrupt signal (high level signal) is applied to the interrupt terminal b. Therefore, when the key switch is turned on while the microcomputer 2 is in the low power consumption state, an interrupt signal is input to the interrupt terminal b, and the normal state can be entered.

  As described above, in the input device 1 of the present embodiment, since the other terminals of the key switches SW1 to SW5 are connected to the interrupt terminal b, the input device 1 shifts from the low power consumption state to the normal state without having a comparator. Can do.

  When an interrupt signal is input to the interrupt terminal b, the microcomputer 2 outputs a low level signal (ground potential) from the interrupt terminal b to the other terminals of the key switches SW1 to SW5. For example, the microcomputer 2 includes a switch 2a between the interrupt terminal b and the ground potential, and outputs a low level signal from the interrupt terminal b by turning on the switch 2a. Can do. Therefore, when one of the key switches is turned on, the other terminal of the key switch is at a low level. Therefore, one end A of the input means 3 is turned on with the other terminal of the key switch being grounded and the power supply voltage V1 is turned on. The voltage is divided by one of the resistors R1 to R5 according to the key switch, and the voltage value can be changed according to the key switch that is turned on.

  Next, processing of the microcomputer 2 in the input device 1 will be described with reference to the flowchart of FIG. The microcomputer 2 sets the interrupt terminal b to the standby state for the interrupt signal when in the low power consumption state. Accordingly, the interrupt terminal b is in a state where the ground potential is connected via the pull-down resistor element R6, and a low-level signal is input. In this state, the microcomputer 2 determines whether or not an interrupt signal (high level) is input to the interrupt terminal b (S1).

  When any key switch is turned on by a user operation, an interrupt signal is input to the interrupt terminal b. That is, when the key switch SW1 is turned on, R6 · V1 / (R1 + R6) is input to the interrupt terminal b. When the key switch SW2 is turned on, R6 · V1 / (R1 + R2 + R6) is input to the interrupt terminal b. When the key switch SW3 is turned on, R6 · V1 / (R1 + R2 + R3 + R6) is input to the interrupt terminal b. When the key switch SW4 is turned on, R6 · V1 / (R1 + R2 + R3 + R4 + R6) is input to the interrupt terminal b. When the key switch SW5 is turned on, R6 · V1 / (R1 + R2 + R3 + R4 + R5 + R6) is input to the interrupt terminal b. That is, when one of the key switches is turned on, a high-level signal that is an interrupt signal is input to the interrupt terminal b.

  It should be noted that the resistance element R1 from the power source V1 is turned on until any key switch is turned on until the microcomputer 2 shifts to the normal state and outputs a low level signal from the interrupt terminal b. The current flows to the ground potential through the key switch (and the resistance element provided in the preceding stage) and the pull-down resistance element R6. However, by setting the resistance value of the pull-down resistance element R6 to a large value (for example, 500 kΩ) (compared to the other resistance elements R1 to R5), the flowing current can be reduced and the power consumption can be reduced. it can.

  When the interrupt signal is input to the interrupt terminal b (YES in S1), the microcomputer 2 shifts from the low power consumption state to the normal state (S2). Then, the microcomputer 2 releases the interrupt terminal b from the standby state of the interrupt signal and sets it to a state where the signal can be input and output.

  The microcomputer 2 outputs a low level signal from the interrupt terminal b to the other terminal of each key switch by turning on the internal switch 2a and connecting the interrupt terminal b to the ground potential inside the microcomputer 2, for example. (S3). As a result, the other terminal of each key switch is directly connected (that is, not via the pull-down resistor element R6 having a large resistance value) to the ground potential (the ground potential inside the microcomputer 2). Therefore, the voltage at the point A input to the key input terminal a can be changed according to the key switch that is turned on. That is, since the resistance value of the pull-down resistance element R6 is set larger than the resistance values of the resistance elements 1 to R5, if a low level signal is not output from the interrupt terminal b, the key is turned on regardless of the key switch that is turned on. This is because the voltage at the point A input to the input terminal a is always substantially V1, and the key switch with the microcomputer 2 turned on cannot be determined.

  Subsequently, the microcomputer 2 starts the operation of the A / D converter. When a voltage is input to the key input terminal a, the microcomputer 2 converts the input voltage from an analog value to a digital value and reads the value. The microcomputer 2 determines the key switch that is turned on from the read voltage value (S4).

  When the key switch SW1 is turned on, since the ground potential is input to the key input terminal a, the microcomputer 2 determines that the key switch SW1 is turned on based on the digital value of this voltage. When the key switch SW2 is turned on, the voltage of R2 · V1 / (R1 + R2) is input to the key input terminal a. Therefore, the microcomputer 2 determines that the key switch SW2 is turned on based on the digital value of this voltage. Judging. When the key switch SW3 is turned on, since the voltage of (R2 + R3) · V1 / (R1 + R2 + R3) is input to the key input terminal a, the microcomputer 2 turns on the key switch SW3 based on the digital value of this voltage. Judge that. When the key switch SW4 is turned on, a voltage of (R2 + R3 + R4) · V1 / (R1 + R2 + R3 + R4) is input to the key input terminal a. Therefore, the microcomputer 2 turns on the key switch SW4 based on the digital value of this voltage. Judge that. When the key switch SW5 is turned on, since the voltage of (R2 + R3 + R4 + R5) · V1 / (R1 + R2 + R3 + R4 + R5) is input to the key input terminal a, the microcomputer 2 turns on the key switch SW5 based on the digital value of this voltage. Judge that.

  After determining the key switch that is turned on, the microcomputer 2 turns off the switch 2a, for example, and releases the interrupt terminal b from the ground potential inside the microcomputer 2, so that a low level signal is not output from the interrupt terminal b. (S5). Therefore, the current again flows from the power source V1 to the ground potential via the resistance element R1, the key switch turned on (and the resistance element provided in the preceding stage), and the pull-down resistance element R6. The flowing current can be reduced, and the power consumption can be reduced. Then, the microcomputer 2 executes a process corresponding to the key switch that has been turned on (S6).

  Next, an input device 101 according to still another preferred embodiment of the present invention will be described. FIG. 3 is a schematic circuit diagram showing the input device 101. The input device 101 has a plurality (two in this example) of input means in parallel. One ends A1 and A2 of the input means 31 and 32 are connected to corresponding key input terminals a1 and a2, respectively. That is, the microcomputer 2 has a key input terminal a1 to which one end A1 of the input means 31 is connected and a key input terminal a2 to which one end A2 of the input means 32 is connected. The other terminals of the key switches SW1 to SW10 of the input means 31 and 32 are connected to the interrupt terminal b and connected to the ground potential via the pull-down resistor element R6. The configuration of the input means 31 and 32 is the same as that of the input means 3 in the circuit diagram of FIG.

  The operation of the input device 101 is substantially the same as that of the input device 1. That is, when the key switch SW6 is turned on, R6 · V1 / (R7 + R6) is input to the interrupt terminal b. When the key switch SW7 is turned on, R6 · V1 / (R7 + R8 + R6) is input to the interrupt terminal b. When the key switch SW8 is turned on, R6 · V1 / (R7 + R8 + R9 + R6) is input to the interrupt terminal b. When the key switch SW9 is turned on, R6 · V1 / (R7 + R8 + R9 + R10 + R6) is input to the interrupt terminal b. When the key switch SW10 is turned on, R6 · V1 / (R7 + R8 + R9 + R10 + R11 + R6) is input to the interrupt terminal b. Therefore, the microcomputer 2 determines that the interrupt signal has been input, and shifts from the low power consumption state to the normal state.

  When the key switch SW6 is turned on, since the ground potential is input to the key input terminal a2, the microcomputer 2 determines that the key switch SW6 is turned on based on the digital value of this voltage. When the key switch SW7 is turned on, a voltage of R8 · V1 / (R7 + R8) is input to the key input terminal a2, so that the microcomputer 2 determines that the key switch SW7 is turned on based on the digital value of this voltage. Judging. When the key switch SW8 is turned on, since the voltage of (R8 + R9) · V1 / (R7 + R8 + R9) is input to the key input terminal a2, the microcomputer 2 turns on the key switch SW8 based on the digital value of this voltage. Judge that. When the key switch SW9 is turned on, since the voltage of (R8 + R9 + R10) · V1 / (R7 + R8 + R9 + R10) is input to the key input terminal a2, the microcomputer 2 turns on the key switch SW9 based on the digital value of this voltage. Judge that. When the key switch SW10 is turned on, a voltage of (R8 + R9 + R10 + R11) · V1 / (R7 + R8 + R9 + R10 + R11) is input to the key input terminal a2, so that the microcomputer 2 turns on the key switch SW10 based on the digital value of this voltage. Judge that.

  In Patent Document 4, when a plurality of input means are provided in parallel, it is necessary to provide an AND circuit. However, according to the input device 101 of the present embodiment, the other terminal of each key switch is commonly connected to the interrupt terminal b, and the other terminal of each key switch is connected to the ground potential via the pull-down resistor element R6. Therefore, the input means 31 and 32 need not be separated from each other by the AND circuit. Therefore, there is no need to provide an AND circuit, the circuit configuration can be simplified, and the cost can be reduced.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment.

  The present invention can be suitably applied to, for example, electronic devices for which power saving during standby is desired, in particular, AV devices such as TVs, audio components, AV receivers and DVD players / recorders, or personal computers.

1 Key input device 2 Control means 3 Input means

Claims (3)

An input means including a resistance element and a plurality of voltage determination circuits including a key switch having one terminal connected to the resistance element and connected in series to each other;
A key input terminal to which one terminal of the key switch included in the voltage determination circuit in the foremost stage is connected, and a control means having an interrupt terminal;
The other terminal of each key switch is connected to the interrupt terminal and connected to the ground potential via a pull-down resistor element,
When the control means is in a low power consumption state and none of the key switches is in the on state, the interrupt terminal is connected to the ground potential via the pull-down resistor element, so that the interrupt terminal When a low-level signal is input and one of the key switches is turned on, a high-level interrupt signal is input to the interrupt terminal, thereby shifting from a low power consumption state to a normal state. ,
When the control means shifts from a low power consumption state to a normal state, the control means outputs a low level signal from the interrupt terminal to the other terminal of each key switch, so that the control means according to the key switch turned on. An input device that determines a key switch that is turned on based on a voltage value that is input to a key input terminal and changes based on the voltage value that is input to the key input terminal.   The control means determines a key switch turned on based on a voltage value input to the key input terminal, and then outputs a low level signal from the interrupt terminal to the other terminal of each key switch. The input device according to claim 1, wherein the input device is stopped. A plurality of the input means are provided in parallel,
The control means has the key input terminal for each input means,
One terminal of the key switch included in each voltage determination circuit in the foremost stage of the plurality of input means is respectively connected to a corresponding key input terminal of the control means,
The input device according to claim 1, wherein the other terminal of each key switch of the plurality of input means is connected to the interrupt terminal and connected to a ground potential via the pull-down resistor element.

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