JP2012238995A - Electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the cost of a product by reducing the number of cables.SOLUTION: An electronic apparatus comprises: a first circuit board on which a key input reception circuit and an infrared reception circuit are mounted; and a second circuit board on which a control unit is mounted. In the first circuit board, the key input reception circuit and the infrared reception circuit are supplied with power source voltage by a common power source. The key input reception circuit, when receiving key input, supplies the control unit with an input signal based on the key input by outputting the input signal having a voltage value within a first voltage range to the second circuit board via one signal line connecting the first circuit board and the second circuit board. The infrared reception circuit, when receiving an infrared signal, makes the control unit obtain an input signal based on the infrared signal by communicating a signal having a voltage value within a second voltage range not overlapping with the first voltage range with the second circuit board via the one signal line.

Description

  The present invention relates to an electronic device that can accept key inputs and infrared signals from the outside.

  A plurality of keys that can be directly operated by the user are provided on the surface of the housing of the product, and key inputs are received through the plurality of keys or infrared signals emitted from an external remote control device (remote control) are received. Electronic devices such as televisions that accept inputs based on signals are well known (see Patent Documents 1 to 4).

Japanese Patent Laid-Open No. 2002-300486 JP 2008-182569 A JP 2010-50782 A JP-A-8-50550

Inside such an electronic device, a key input receiving circuit for receiving a key input and an infrared receiving circuit for receiving an infrared signal are each mounted on a substrate. Further, inside the electronic device, a main IC (Integrated Circuit) that controls the entire device is mounted on another substrate (main substrate). Conventionally, a signal line (cable) for connecting the key input receiving circuit and the main IC and a signal line (cable) for connecting the infrared receiving circuit and the main IC are separately provided between these substrates. It was. In addition, the electronic device includes a light emitting diode for notifying the user of the product state (for example, power ON / OFF state) by turning on / off, and for each of the key input receiving circuit, the infrared receiving circuit, and the light emitting diode. A power source for driving them is supplied from a power supply circuit. Here, the key input acceptance circuit, the infrared receiving circuit, and the light emitting diode have different voltage levels required for driving. Therefore, a plurality of power supply lines corresponding to the supply of different voltage levels are provided. The power supply voltage required for each of the above-described configurations was supplied from the supply line.
However, from the viewpoint of cost reduction in electronic device manufacturing, it is required to reduce each line such as a cable provided in the product as much as possible.

  The present invention has been made to solve the above-described problems, and provides an electronic device capable of reducing the cost as compared with the related art by reducing the number of lines connecting the components as much as possible.

  One aspect of the present invention acquires a key input receiving circuit for receiving a key input, an infrared receiving circuit for receiving an infrared signal, an input signal based on the key input, and an input signal based on the infrared signal. An electronic device including a control unit, the first substrate including at least the key input receiving circuit and the infrared receiving circuit, and a second substrate mounting at least the control unit. Then, the key input receiving circuit and the infrared receiving circuit are supplied with a power supply voltage from a common power source, and the key input receiving circuit receives an input signal whose voltage value is within the first voltage range when receiving the key input. Is output to the second substrate via a single signal line connecting the first substrate and the second substrate, thereby supplying an input signal based on key input to the control unit. Receive signal When a signal having a voltage value within a second voltage range that does not overlap with the first voltage range is communicated with the second substrate via the single signal line, the control unit An input signal based on an infrared signal is acquired.

  According to this configuration, the key input receiving circuit communicates a signal whose voltage value is within the first voltage range with the control unit, and the infrared receiving circuit has the first voltage value with the control unit. A signal line connecting the key input receiving circuit and the control unit and a signal line connecting the infrared receiving circuit and the control unit between the two substrates by communicating a signal within the second voltage range that does not overlap with the range; Are unified (shared). As a result, the cost of the electronic device can be reduced by reducing the conventional two signal lines to one.

It is a figure which shows an example of schematic structure of an electronic device. It is a figure which shows the structure containing a 1st board | substrate and a 2nd board | substrate.

As an embodiment of the present invention, the first board supplies a power supply voltage lower than the power supply voltage supplied to the key input receiving circuit to the infrared receiving circuit, and the second voltage range is lower than the first voltage range. It is good.
As an embodiment of the present invention, the second substrate includes a first extraction circuit that inputs a signal onto a second signal line that connects the one signal line and the control unit, and the first extraction circuit includes an input It is good also as a structure which cuts the voltage lower than the minimum of the 1st voltage range for the signal which was made into an object, and supplies the input signal by the voltage which remained after the cut to the control part side.
As an embodiment of the present invention, the infrared receiving circuit includes a first board side switch circuit that performs switching according to a pulse signal based on the received infrared signal, and the second board controls the one signal line. A second extraction circuit on a third signal line connecting the first and second sections, and the second extraction circuit includes a diode that prohibits at least the input of a voltage equal to or lower than the upper limit of the first voltage range to the control unit side. And switching between the transmission and non-transmission of the signal within the second voltage range to the first substrate via the one signal line in conjunction with the switching of the first substrate side switch circuit. A second substrate-side switch circuit may be provided, and the second substrate-side switch circuit may generate an input signal having a waveform corresponding to the pulse signal based on the switching and supply the input signal to the control unit.
As an embodiment of the present invention, the first substrate may be configured to supply a power supply voltage to the light emitting diodes that are controlled to be turned on / off by the control unit from the common power source.

Further, as a further detailed embodiment of the present invention, a key input receiving circuit for receiving a key input, an infrared receiving circuit for receiving an infrared signal, an input signal based on the key input, and an input signal based on the infrared signal, A first board on which the key input receiving circuit, the infrared receiving circuit, and a light emitting diode that is controlled to be turned on / off by the control IC, A first extraction circuit for extracting an input signal based on the key input; a second extraction circuit for extracting an input signal based on an infrared signal; and a second substrate on which a control IC is mounted. In the first board, the key input receiving circuit, the infrared receiving circuit, and the light emitting diode are supplied with a power supply voltage from a common power source, and the key input receiving circuit is provided on the power source and the first board. Each input that is connected in series to a plurality of key input circuits each having a different resistance value for each input circuit and a switch that conducts contact between the contacts when the key input is received. A voltage value corresponding to the resistance of the input circuit when the key input is received via the key of any one of the input circuits and within the first voltage range. An input signal is output to the second board via a single signal line connecting the first connector and the second connector provided on the second board, and the infrared receiving circuit is connected between the power source and the first connector. An infrared sensor that is connected in parallel with the key input receiving circuit and operates by receiving a power supply voltage lower than the power supply voltage supplied to the key input receiving circuit by connecting the power supply via a predetermined resistor; Infrared sensor A first transistor having a base connected to the output signal line, and a second transistor having a base connected to the collector of the first transistor. The first transistor outputs an infrared signal when the infrared sensor receives the infrared signal. In accordance with the pulse signal based on the infrared signal, switching is performed to switch on and off, the second transistor performs switching to switch on and off in the opposite phase to the switching of the first transistor, and the second substrate includes the second connector. The first extraction circuit for inputting a signal on a second signal line connecting the control IC and the control IC, and the second extraction circuit on a third signal line connecting the second connector and the control IC, The first extraction circuit is a Zener diode having a cathode connected to the second connector side and an anode connected to the control IC side. The voltage dividing ratio between the Zener diode that cuts a voltage lower than the lower limit of the first voltage range for the input signal and the resistance of the input circuit that receives the key input is the voltage on the anode side of the Zener diode. A voltage dividing resistor, and the divided voltage is supplied to the control IC as an input signal based on the key input, and the second extraction circuit controls the anode by connecting the cathode to the second connector side. A diode that is connected to the IC side and prohibits the input to the control IC side of a voltage that is at least lower than the upper limit of the first voltage range; and a base connected to the anode of the diode and a collector in the second substrate And a third transistor whose base is pulled up by the predetermined power source, and does not overlap with the first voltage range. By switching between transmission and non-transmission of the signal in the second voltage range lower than the voltage range to the first substrate via the one signal line in synchronization with on / off of the second transistor, An input signal having a waveform corresponding to the pulse signal output to the first transistor may be generated and supplied to the control IC.
Although the invention as an electronic device has been described above, a circuit configuration including the first substrate, the second substrate, and a signal line connecting both the substrates included in the electronic device can be extracted as one invention. .

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram illustrating an example of a schematic configuration of an electronic device 10 to which the present invention is applied. The electronic device 10 is, for example, a liquid crystal television. However, as an electronic device to which the present invention is applied, a product (player, recorder, monitor) including a circuit for receiving a key input by a user and a circuit for receiving an infrared signal (remote control signal) emitted from a remote controller. Etc.) any product. The electronic device 10 as a liquid crystal television is configured to receive a television broadcast signal of a channel selected from a television broadcast signal received by an antenna 12 and a main IC 11 (control unit or control IC) that controls the operation of the main body. The tuner 13 that is extracted and output, the video processing unit 15 that displays the video based on the television broadcast signal output from the tuner 13 on the liquid crystal panel 14, and the audio that is based on the television broadcast signal output from the tuner 13 from the speaker 16. An audio processing unit 17 to output, an infrared receiving circuit 19 that receives an infrared signal transmitted from an external remote controller 18, and a plurality of keys (buttons) that can be directly operated by a user are arranged at predetermined positions on the housing surface of the electronic device 10. And a key input receiving circuit 21 for receiving a key input from a user, and operating power to each unit It includes a power supply circuit 20 for supplying a.

  Based on the infrared signal received by the infrared receiving circuit 19 and the key input received by the key input receiving circuit 21, the main IC 11 turns on / off the power, switches the channel, increases / decreases the volume, and inputs the input source (HDMI input, Control switching of video input, component input, etc.).

  FIG. 2 shows a configuration in which the first board 22 (IR / KEY board) on which the infrared receiving circuit 19 and the key input receiving circuit 21 are mounted, the main IC 11 and the like are mainly mounted. A configuration including a substrate 23 (main substrate) is shown. The first board 22 includes a connector 22a (first connector), the second board 23 includes a connector 23a (second connector), and a single signal line (cable 24) is provided between the connector 22a and the connector 23a. It is connected.

  In addition to the above configuration, the first substrate 22 includes a light emitting diode D1 and an LED control unit 22b for controlling lighting / extinguishing of the light emitting diode D1. The light emitting diode D1 is, for example, a white LED. A power supply Vcc of a predetermined level (+7 V in this embodiment) is supplied to the first substrate 22 from the power supply circuit 20 (FIG. 1), and the key input receiving circuit 21, the infrared receiving circuit 19 and the light emitting diode D1 are All are driven by receiving a supply voltage from the common power supply Vcc.

  The light emitting diode D1 has an anode connected to the common power source Vcc, and the LED control unit 22b is connected to the cathode of the light emitting diode D1 through a resistor R11. The LED control unit 22b is connected to the main IC 11, and controls the light emitting diode D1 in response to a predetermined high (H) level or low (L) level control signal output from the output terminal 11c. Specifically, when an H level control signal is received from the main IC 11, the light emitting diode D 1 is turned off without energization between the anode and the cathode of the light emitting diode D 1, and an L level control signal is received from the main IC 11. Energizes the light emitting diode D1 to turn on the light emitting diode D1. Accordingly, it can be said that the light-emitting diode D1 is controlled to be turned on / off by the main IC 11. For example, the light emitting diode D1 turns on to indicate to the outside that the electronic device 10 is in a power-on state, and turns off to indicate to the outside that the electronic device 10 is in a power-off (standby mode).

  The key input receiving circuit 21 is an input circuit for each of a plurality of keys between the common power supply Vcc and the connector 22a. When the key input receiving circuit 21 receives a key input with a resistance having a different resistance value for each input circuit, the key input receiving circuit 21 Each input circuit connected in series with a switch that conducts is connected in parallel. In the example of FIG. 2, an input circuit consisting of a resistor R1 and a switch SW1, an input circuit consisting of a resistor R2 and a switch SW2, an input circuit consisting of a resistor R3 and a switch SW3, an input circuit consisting of a resistor R4 and a switch SW4, a resistor R5 and a switch An input circuit made up of SW5 and an input circuit made up of a resistor R6 and a switch SW6 constitute a key input receiving circuit 21. The switches SW1 to SW6 correspond to keys such as power on / off, channel up, channel down, input source switching, volume up, volume down, etc., when the user operates (presses) a key arbitrarily selected. In addition, a switch corresponding to the operated key conducts between the contacts in the input circuit.

  For example, when a key corresponding to the switch SW1 is operated, the contacts at both ends of the switch SW are brought into conduction, and a current flows through an input circuit applied to the switch SW1. At this time, a voltage value is generated on the output side (21a) of the key input receiving circuit 21 after dropping from the voltage (+ 7V) of the common power supply Vcc according to the resistor R1. That is, when one of the input circuits receives a key input from the user, a voltage value that varies depending on the resistances R1 to R6 of the input circuit that has received the key input, on the output side (21a) of the key input receiving circuit 21. Will occur. The voltage values generated in this way are all set to a predetermined range (first voltage range) that is lower than + 7V and higher than + 3.3V in this embodiment. Therefore, when any of the input circuits receives a key input from the user, an input signal whose voltage value is within the first voltage range is output from the connector 22a, and the second substrate 23 is connected via the cable 24 and the connector 23a. Is input.

  In addition to the main IC 11, the second substrate 23 includes a first extraction circuit 23b for extracting an input signal based on the key input and a second extraction circuit 23c for extracting an input signal based on an infrared signal. Has been. The first extraction circuit 23 b is provided on a signal line 23 d (second signal line) connecting the connector 23 a and the input terminal 11 a of the main IC 11, and the second extraction circuit 23 c is connected to the connector 23 a and the input terminal 11 b of the main IC 11. Are provided on a signal line 23e (third signal line). The second extraction circuit 23c includes a diode D3 having a cathode connected to the connector 23a side and an anode connected to the main IC 11 side, and at least a diode D3 that prohibits inflow of a voltage not exceeding the upper limit value of the first voltage range. doing. Therefore, an input signal based on the key input output from the key input reception circuit 21 does not flow into the second extraction circuit 23c.

  On the other hand, the first extraction circuit 23b is a Zener diode Z2 having a cathode connected to the connector 23a side and an anode connected to the main IC 11. It has a Zener diode Z2 that cuts the corresponding voltage. Accordingly, when an input signal (an input signal having a voltage value higher than the Zener voltage) based on the key input output from the key input receiving circuit 21 is input to the second substrate 23 through the cable 24 and the connector 23a, the first signal is input. A signal having a voltage value after the voltage (+3.3 V) less than the lower limit of the voltage range is cut (pulled) is generated on the anode side of the Zener diode Z2. This signal is further divided in accordance with the voltage dividing ratio between the resistor (any one of resistors R1 to R6) and resistor R0 included in the input circuit that has received the key input, and the first signal is input via the resistor R12. The signal is output from the extraction circuit 23b and input to the input terminal 11a of the main IC 11 as an input signal based on the key input.

  In the main IC 11, when an input signal based on the key input is input, the voltage value is compared with a plurality of threshold values defined in advance for comparison with the input signal based on the key input. Then, it is determined whether the input signal input at that time corresponds to a signal indicating what kind of operation (power on / off, channel up, channel down, input source switching, volume up, volume down, etc.), and electronic control is performed according to the judgment result. Each component of the device 10 is controlled.

  The infrared receiving circuit 19 is connected in parallel with the key input receiving circuit 21 between the common power supply Vcc and the connector 22a. The infrared receiving circuit 19 includes an infrared sensor (IR sensor) 19a, a transistor Q1 (first transistor) as a switching element, a transistor Q2 (second transistor), and the like. The IR sensor 19a is connected to the common power supply Vcc via the resistor R7, and operates by receiving a power supply voltage lower than the power supply voltage supplied to the key input receiving circuit 21 at the Vcc terminal. Specifically, the power supply voltage passing through the resistor R7 is a constant voltage (a constant voltage of + 3.3V) by the action of the Zener diode Z1 in which the cathode is connected to the line between the resistor R7 and the Vcc terminal and the anode is grounded. And supplied to the Vcc terminal. In addition, the IR sensor 19a includes a ground (GND) terminal and an output (Vout) terminal, photoelectrically converts the received infrared signal to generate a pulse signal, and outputs the pulse signal from the Vout terminal.

  The transistor Q1 is an NPN transistor in which the base is connected to the output signal line from the Vout terminal via the resistor R8, the emitter is grounded, and the collector is connected to the output side of the resistor R7 via the resistor R9. The transistor Q2 is an NPN transistor in which the base is connected to the collector of the transistor Q1 (between the collector of the transistor Q1 and the resistor R9), the emitter is grounded, and the collector is connected to the cathode of the diode D2. Further, a resistor R10 is interposed between the anode of the diode D2 and the connection point between the resistors R7 and R9. The connection point (the output side (19b) of the infrared receiving circuit 19) between the cathode of the diode D2 and the collector of the transistor Q2 joins the output side (21a) of the key input receiving circuit 21 and is connected to the connector 22a. Yes. The diode D <b> 2 prevents the signal output from the key input reception circuit 21 from flowing into the infrared receiving circuit 19.

  In such an infrared receiving circuit 19, when the remote controller 18 is not operated, the IR sensor 19a continues to output a predetermined H level signal from the Vout terminal. As a result, the base of the transistor Q1 is maintained at a predetermined high potential and is kept on (collector-emitter conduction), and the base of the transistor Q2 is turned off at a predetermined low potential as the transistor Q1 is turned on. The state (collector-emitter non-conduction) is maintained. During such no operation, the infrared receiving circuit 19 generates a voltage (signal) on the output side (19b), but is surely lower than the lower limit of the first voltage range (+ 3V) by the action of the resistors R7, R9, and R10. The following signal). Therefore, even if the signal output from the infrared receiving circuit 19 in this way is input to the second substrate 23 side through the cable 24, the Zener diode Z2 and the diode D3 are prohibited from inflowing to the second substrate 23, and the signal is There is no input to the main IC 11 side.

  When operating the remote controller 18, the IR sensor 19a outputs a pulse signal based on the received infrared signal from the Vout terminal. The transistor Q1 performs switching for switching on and off in accordance with switching between the H level and the L level of the pulse signal input to the base. The transistor Q2 performs switching to switch on and off in the opposite phase to the switching of the transistor Q1, by switching the base potential between the L level and the H level in accordance with the switching of the transistor Q1.

  The second extraction circuit 23c has a base connected to the anode of the diode D3 via a resistor R13, and has a predetermined level (+3.3 V in this embodiment) supplied from the power supply circuit 20 (FIG. 1) to the second substrate 23. An NPN transistor Q3 having a collector connected to the second power supply Vcc and an emitter grounded via a resistor R15 is provided. In addition, since the connection point between the anode of the diode D3 and the resistor R13 is connected to the second power supply Vcc via the resistor R14, the base of the transistor Q3 is pulled up by the second power supply Vcc. In such a configuration, in synchronization with the ON state of the transistor Q2 of the infrared receiving circuit 19, a current flows from the second extraction circuit 23c side to the transistor Q2 via the signal line 23e, the connector 23a, the cable 24, and the connector 22a. The base of the transistor Q3 becomes a predetermined low potential and is turned off. That is, an electrical signal is transmitted from the second extraction circuit 23 c to the first substrate 22 side via the cable 24. The range of the voltage of the signal transmitted at this time is +3 V or less due to the action of the resistor R14. This is a signal in a voltage range (second voltage range) that does not overlap with the first voltage range and is lower than the first voltage range. As described above, the signal transmitted by the second extraction circuit 23c can also flow into the signal line 23d. However, since the voltage is lower than the lower limit of the first voltage range, the Zener diode Z2 reliably supplies the signal to the first extraction circuit 23b. Inflow is prohibited.

  On the other hand, when the transistor Q2 is turned off, the transistor Q3 is turned on by pulling up the base of the transistor Q3 by the second power supply Vcc (transmission of a signal from the second extraction circuit 23c to the first substrate 22 side). No). That is, the second extraction circuit 23c switches the timing for transmitting the signal within the second voltage range to the first substrate 22 via the cable 24 and the timing for not transmitting in synchronization with the on / off of the transistor Q2. Thus, the transistor Q3 performs switching to switch on and off in the opposite phase to the switching of the transistor Q2. As a result, a signal (pulse signal) having a waveform corresponding to the pulse signal output from the IR sensor 19a to the transistor Q1 is generated on the emitter side of the transistor Q3, and this signal is output to the second extraction circuit via the resistor R16. 23c and input to the input terminal 11b of the main IC 11 as an input signal based on the infrared signal. The main IC 11 controls each component of the electronic device 10 according to an input signal based on the infrared signal.

  The configuration including the transistors Q1 and Q2 in the infrared receiving circuit 19 corresponds to the first substrate side switch circuit, and the configuration including the transistor Q3 in the second extraction circuit 23c corresponds to the second substrate side switch circuit. .

  As described above, according to the present embodiment, the key input receiving circuit 21 and the infrared receiving circuit 19 are mounted on the first substrate 22, the main IC 11 is mounted on the second substrate 23, and the key input receiving circuit 21 When the signal is received, a signal whose voltage value is within the first voltage range is output to the second IC board 23 via the single cable 24 connecting the first board 22 and the second board 23 to the main IC 11. When the infrared signal is received by the IR sensor 19a, the infrared receiving circuit 19 supplies an input signal based on a key input, and the voltage value does not overlap with the first voltage range and is lower than the first voltage range. By communicating (receiving) a signal within the voltage range with the second substrate 23 via the one cable 24, the main IC 11 acquires an input signal based on the infrared signal.

  That is, a voltage range of a signal for transmitting an input based on a key input from the IR / KEY board to the main IC 11 mounted on the main board side, and an infrared signal from the IR / KEY board to the main IC mounted on the main board side. By making the voltage range of signals to be communicated different in order to obtain the input based on it, it becomes possible to use a common signal line for these two types of communication, and as a result, a single cable connecting the two boards is used. Can be. Conventionally, the IR / KEY board and the main board are connected to each other for each communication so that these two types of communication are not mixed. However, according to this embodiment, the number of cables is reduced, and the electronic device 10 It has become possible to reduce the cost of manufacturing.

  Conventionally, a power supply voltage of about +3.3 V is supplied from the power supply circuit 20 to the key input receiving circuit 21 and the infrared receiving circuit 19 through one power supply line as a power source for driving them. In addition, a power supply voltage of about +5 V is supplied from the power supply circuit 20 to the light emitting diode D1 through another power supply line as a power source for driving the light emitting diode D1. However, in order to realize a configuration that uses a common signal line (cable 24) for the two types of communication as in the present embodiment, it is necessary to vary the voltage ranges used for the two types of communication. A high power supply of +7 V that satisfies the first voltage range, which is the higher voltage range, is supplied to the key input receiving circuit 21 and the infrared receiving circuit 19. As a result, such a power supply is sufficient as a driving voltage for the light-emitting diode D1, so that it is not necessary to separately provide a line for supplying power to the light-emitting diode D1 as in the prior art. The power supply voltage can be supplied from the common power supply Vcc to the infrared receiving circuit 19 and the light emitting diode D1. That is, compared to the conventional case, the number of power supply lines from the power supply circuit 20 can be reduced by one, and the cost for manufacturing the electronic device 10 can be further reduced.

DESCRIPTION OF SYMBOLS 10 ... Electronic device, 11 ... Main IC, 11a, 11b ... Input terminal, 11c ... Output terminal, 18 ... Remote control, 19 ... Infrared receiving circuit, 19a ... IR sensor, 20 ... Power supply circuit, 21 ... Key input reception circuit, 22 ... 1st board | substrate, 22a, 23a ... Connector, 22b ... LED control part, 23 ... 2nd board | substrate, 23b ... 1st extraction circuit, 23c ... 2nd extraction circuit, 23d, 23e ... Signal wire, 24 ... Cable

Claims (6)

An electronic device comprising a key input receiving circuit for receiving key input, an infrared receiving circuit for receiving an infrared signal, and a control unit for acquiring an input signal based on the key input and an input signal based on the infrared signal Because
A first board on which at least the key input receiving circuit and an infrared receiving circuit are mounted; and a second board on which at least the control unit is mounted.
In the first substrate, the key input receiving circuit and the infrared receiving circuit are supplied with a power supply voltage from a common power source,
When receiving the key input, the key input receiving circuit receives an input signal having a voltage value within the first voltage range via a single signal line connecting the first substrate and the second substrate. To output an input signal based on key input to the control unit,
When the infrared receiving circuit receives an infrared signal, a signal whose voltage value is in a second voltage range that does not overlap with the first voltage range is transmitted to the second substrate via the one signal line. An electronic apparatus characterized by causing a control unit to acquire an input signal based on an infrared signal by communicating between them.   The power supply voltage lower than the power supply voltage supplied to the key input receiving circuit is supplied to the infrared receiving circuit in the first substrate, and the second voltage range is lower than the first voltage range. The electronic device as described in.   The second substrate includes a first extraction circuit that inputs a signal onto a second signal line connecting the one signal line and the control unit, and the first extraction circuit uses a first voltage for the input signal. The electronic apparatus according to claim 2, wherein a voltage lower than a lower limit of the range is cut, and an input signal based on the voltage remaining after the cut is supplied to the control unit side. The infrared receiving circuit includes a first substrate side switching circuit that performs switching according to a pulse signal based on the received infrared signal,
The second substrate includes a second extraction circuit on a third signal line connecting the one signal line and the control unit, and the second extraction circuit is a control unit for a voltage at least equal to or lower than the upper limit of the first voltage range. A diode that prohibits input to the side, and the signal line of the signal within the second voltage range is connected between the diode and the control unit in conjunction with switching of the first substrate side switch circuit. A second board-side switch circuit that switches between transmission and non-transmission to the first board via the first board, and the second board-side switch circuit generates and controls an input signal having a waveform corresponding to the pulse signal based on the switching. The electronic device according to claim 2, wherein the electronic device is supplied to a part.   5. The electron according to claim 1, wherein the first substrate supplies a power supply voltage to the light emitting diode controlled to be turned on / off by the control unit from the common power supply. machine. An electronic device comprising a key input receiving circuit for receiving a key input, an infrared receiving circuit for receiving an infrared signal, and a control IC for acquiring an input signal based on the key input and an input signal based on the infrared signal Equipment,
A first substrate on which the key input receiving circuit, the infrared receiving circuit, and a light emitting diode that is controlled to be turned on / off by a control IC;
A first extraction circuit for extracting an input signal based on the key input; a second extraction circuit for extracting an input signal based on an infrared signal; and a second board on which a control IC is mounted.
In the first substrate, the key input receiving circuit, the infrared receiving circuit, and the light emitting diode are supplied with a power supply voltage from a common power source,
The key input receiving circuit is an input circuit for each of a plurality of keys between the power source and the first connector provided on the first board, and receives a key input with a resistance having a different resistance value for each input circuit. A voltage that corresponds to the resistance of the input circuit when a key input is received via a key of one of the input circuits. And an input signal having a voltage value within the first voltage range is output to the second board via a single signal line connecting the first connector and the second connector provided on the second board. ,
The infrared receiving circuit is connected in parallel with the key input receiving circuit between the power source and the first connector, and is connected to the power source through a predetermined resistor, so that the power receiving voltage is supplied to the key input receiving circuit. An infrared sensor that operates upon receiving a low power supply voltage; a first transistor having a base connected to an output signal line from the infrared sensor; and a second transistor having a base connected to a collector of the first transistor; The first transistor performs switching to switch on and off in accordance with a pulse signal based on the infrared signal that is output when the infrared sensor receives the infrared signal, and the second transistor is switched on and off in the opposite phase to the switching of the first transistor. Switching to switch between
The second substrate includes the first extraction circuit for inputting a signal on a second signal line connecting the second connector and the control IC, and on the third signal line connecting the second connector and the control IC. Comprising the second extraction circuit;
The first extraction circuit is a Zener diode having a cathode connected to the second connector side and an anode connected to the control IC side, and cuts a voltage lower than the lower limit of the first voltage range for the input signal. A diode and a resistor that divides the voltage on the anode side of the Zener diode in accordance with a voltage dividing ratio between the resistor of the input circuit that has received the key input, and the divided voltage is input based on the key input. Supply it to the control IC as a signal,
The second extraction circuit is a diode having a cathode connected to the second connector side and an anode connected to the control IC side, and prohibits at least input of a voltage below the upper limit of the first voltage range to the control IC side. And a third transistor having a base connected to the anode of the diode, a collector connected to a predetermined power source in the second substrate, and a base pulled up by the predetermined power source. The transmission and non-transmission of the signal in the second voltage range lower than the first voltage range to the first substrate via the one signal line is synchronized with the on / off of the second transistor. Switching to generate an input signal having a waveform corresponding to the pulse signal output to the first transistor, and supply it to the control IC
An electronic device characterized by that.

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