JP6131742B2 - Electronic equipment - Google Patents

Description

  The present invention relates to an electronic device.

  Most electronic devices such as home appliances, digital televisions, personal computers, and vending machines operate under the control of a microcomputer (hereinafter abbreviated as “microcomputer”). The microcomputer is operated by a signal from a pulse generator (so-called oscillation circuit) having a constant period called a clock. The signal of this generator may leak and affect the low channel (1-3 ch, etc.) of the television from the radio band as noise (radio noise, radiation noise).

  In addition, the wiring pattern on the substrate and the wiring pattern next to the wiring pattern, for example, have a resonance frequency due to the inductance of the wiring pattern itself and the line capacitance generated between other wiring patterns, and the resonance frequency is If it is included in the radio frequency band, radio noise may be generated.

  Therefore, the wiring pattern for commonly supplying power to the plurality of connection terminals of the electronic component is formed into a single wire shape that sequentially passes through the connection points of the plurality of connection terminals that are electrically connected to the wiring pattern, and the ground pattern is There has been devised an electronic device in the form of a single wire that passes through the connection points of the plurality of connection terminals that are electrically connected to the ground pattern in sequence (see Patent Document 1).

  In addition, based on the tuning frequency of the radio mounted on the vehicle, the frequency of the electrical signal output from the capacitance detection circuit to the sensor electrode provided on the vehicle seat is changed, thereby radiating from the sensor electrode. A sensor device for reducing radio noise generated by an electrical signal is devised (see Patent Document 2).

Japanese Patent No. 3619129 JP 2007-269261 A

  In the configuration of Patent Document 1, if the circuit configuration changes, it is necessary to redesign the pattern wiring, and the design man-hour increases. Further, due to the configuration of the pattern wiring, there are noise peaks (resonance frequencies) at a large number of frequencies, so that sufficient radio noise countermeasures cannot be taken.

  In the configuration of Patent Document 2, an oscillation circuit and a frequency dividing circuit for outputting a plurality of frequencies are required, and the circuit becomes large. Further, depending on the frequency of the electric signal, the performance of the sensor may be deteriorated.

  In view of the above problems, an object of the present invention is to provide an electronic device capable of taking measures against radio noise at a low cost.

Means for Solving the Problems and Effects of the Invention

  An electronic device for solving the above problems includes an electronic component mounted on a circuit board, a variable capacitance circuit provided between a signal line connected to the electronic component and ground, and an operating state of another device. An information acquisition circuit that acquires operation state information reflecting the above and a capacitance setting circuit that sets the capacitance of the variable capacitance circuit based on the acquired operation state information.

  With the above configuration, it is possible to reduce the generation of noise from electronic components or signal lines. By adding the capacitance of the variable capacitance circuit, the line frequency capacitance between the signal line and its peripheral circuit and other signal lines, and the resonance frequency due to the inductance of the signal line and its peripheral circuit, the frequency used by other devices And the generation of noise for the frequency can be reduced. Further, by making the capacitance variable, it is possible to reduce the generation of noise for a plurality of frequency bands.

1 is a diagram illustrating a configuration of an electronic device according to the present invention (Example 1). FIG. FIG. 3 is a flowchart for explaining a capacity switching control process (first embodiment). FIG. 10 is a diagram illustrating another example of the configuration of the electronic device in FIG. 1 (first embodiment). FIG. 10 is a diagram illustrating another example of the configuration of the electronic device in FIG. 1 (first embodiment). FIG. 10 is a diagram illustrating a configuration of an electronic device (second embodiment). FIG. 6 is a diagram illustrating another example of the configuration of the electronic device in FIG. 5 (second embodiment). FIG. 6 is a diagram illustrating another example of the configuration of the electronic device in FIG. 5 (second embodiment). FIG. 9 is a flowchart for explaining capacity switching control processing (second embodiment). FIG. 9 is a flowchart for explaining recommended value determination processing (second embodiment).

  Hereinafter, a first embodiment of an electronic device according to the present invention will be described with reference to the drawings. FIG. 1 shows a configuration of the electronic device 1. The electronic device 1 is mounted on a vehicle, for example, an electronic control device (hereinafter referred to as ECU) 10 that controls operation of various functions of the vehicle, and a radio (also referred to as a radio receiver) 20 connected to the ECU 10 via an in-vehicle LAN 30. Including communication devices. Note that the radio 20 may be capable of receiving audio from a television (TV) broadcast. The ECU 10 includes a sensor group and an actuator group necessary for realizing a predetermined function, but is omitted because it is not directly related to the configuration of the present invention.

  The above-described configuration is “the other device is a radio receiver”. With this configuration, it is possible to reduce the radio noise from being mixed into the frequency being listened to by the radio receiver, and the listener can be prevented from feeling uncomfortable due to the radio noise.

  In addition, a plurality of other devices may be connected to the ECU 10. In addition to radio, mobile communication terminals can be cited.

  The electronic device 1 is a vehicle side of a keyless entry system 40 that executes predetermined functions of the vehicle (for example, door unlocking / locking, engine start permission, etc.) based on wireless communication with the portable device 42 possessed by the user. It is good also as a structure containing the communication apparatus 41 (connection with the vehicle side communication apparatus 41 and the microcomputer 11 is abbreviate | omitted). This configuration is “the other device is a vehicle-side communication device mounted on a vehicle in a keyless entry system that executes a predetermined function of the vehicle based on wireless communication with a portable device possessed by the user”. With this configuration, it is possible to reduce the mixing of noise into the vehicle-side communication device, and it is possible to prevent the phenomenon that the operation corresponding to the operation is not executed even when the user operates the portable device or the door knob.

  The ECU 10 includes a well-known microcomputer 11 (electronic parts and capacity setting circuit of the present invention), ROM and RAM storing various programs (collectively referred to as “control program”), and a signal input / output circuit (all (Not shown), a power supply circuit 12 that supplies power from the battery 61 to each part of the ECU 10, a LAN I / F 18 (information acquisition circuit, information output circuit of the present invention) that is a communication interface circuit of the in-vehicle LAN 30 and the like. And the microcomputer 11 implement | achieves the various functions as the electronic device 1 by running a control program. These components and circuits are mounted on a circuit board 19 which is also called a known printed board.

  The microcomputer 11 includes a capacitor switching circuit 11a (capacitance setting circuit of the present invention), an oscillation circuit 11b, and the like. For example, the capacitor switching circuit 11a uses an output port of the microcomputer 11 and outputs an on or off signal to the switches SW1 to SW3 and SW10 by switching the state of the output port. The oscillation circuit 11b includes a frequency dividing circuit or a multiplication circuit as necessary, and generates a clock signal necessary for the operation of the microcomputer 11.

  The power supply circuit 12 supplies power to each part of the ECU 10 by a current limiting resistor R0, a Zener diode D0 for generating a constant voltage (for example, 5V), and a capacitor C0 that is an input / output capacitor for stabilizing the voltage. Supply.

  Further, the output side of the power supply circuit 12 includes a variable capacitance circuit 12a. The variable capacitance circuit 12a has a plurality of capacitors (C1 to C3, C10) connected in parallel. One end of each capacitor is connected to the power supply line 12b (signal line of the present invention), and the other end is connected to a switch ( It is connected to the ground (GND) via SW1 to SW3 and SW10).

  Further, the length and thickness of each wiring pattern on the circuit board 19 (that is, the capacitance between the lines) between the capacitors (C1 to C3, C10) to the switches (SW1 to SW3, SW10) to GND are substantially the same. It is desirable to be.

  The configuration described above is “a signal line is a power line for supplying power to an electronic component”. With this configuration, it is possible to reduce the generation of noise (for example, harmonics generated by the oscillation circuit 11b that are close to the frequency being used) from the power supply line and its peripheral circuits with respect to the frequency being used by another device. it can.

  Capacitors C1 to C3 reduce the occurrence of the above-described radio noise. For example, the capacity of C1 is set so as to reduce radio noise generated in a TV broadcast band (for example, 470 MHz to 770 MHz). Similarly, the capacitor C2 reduces radio noise generated in the FM broadcast band (for example: 76 MHz to 108 MHz), and the capacitor C3 reduces radio noise generated in the AM broadcast band (for example: 510 kHz to 1710 kHz). The capacity is set.

  Capacitor C10 has a capacity set so as to reduce radio noise generated at a frequency (for example, 315 MHz band) used by vehicle-side communication device 41. In addition, a tire pressure monitoring system (not shown) that installs an air pressure sensor in the tire and informs the driver of air pressure information in the running tire also uses a radio for the system when using the 315 MHz band. Noise generation can also be reduced. Further, the capacitance may be set so that the capacitor C1 can also serve as the capacitor 10.

  The capacity switching control process executed by the microcomputer 11 will be described with reference to FIG. First, radio state information (operation state information of the present invention) indicating whether or not the radio 20 is in an on state is acquired from a communication signal via the in-vehicle LAN 30 and the LAN I / F 18 (S11). The radio state information is also used as frequency information to be described later. For example, when the frequency is not included in the frequency band of each broadcast described above, the radio 20 is in an off state and is included in the frequency band of each broadcast described above. When the radio 20 is on, it may be determined that the radio 20 is on. In addition, when the radio state information includes the on / off state of the radio 20, the state is determined based on this information.

When the radio 20 is not on (S12: No), the capacitor switching circuit 11a selects a default capacity (S18). One of the following is used as the default capacity.
-Capacitor C1: Combined with the capacity when receiving TV broadcasts. Only the switch SW1 is turned on.
Capacitor C10: set to a capacity that does not affect the operation of the keyless entry system 40 (or tire pressure monitoring system). Only the switch SW10 is turned on.

  When the radio 20 is not in the on state, it is considered that the vehicle is often parked or the passenger is not in the vehicle. Therefore, the keyless entry system 40 (which often operates mainly when the vehicle is parked or the passenger is not in the vehicle). Alternatively, the influence of radio noise can be reduced even in a tire pressure monitoring system). In this way, the configuration using the capacitor C10 as the default capacitance is “the capacitance setting circuit has another device to be used when setting the capacitance of the variable capacitance circuit based on the frequency information acquired by the information acquisition circuit. Is different from other target devices when setting the default capacity ”. As a result, radio noise reduction devices (that is, “other devices”), such as a device that operates when the occupant is not on board, and a device that operates when the occupant is on board, Multiple types can be used.

  On the other hand, when the radio 20 is on (S12: Yes), frequency information (operation state information of the present invention) is acquired via the in-vehicle LAN 30 and the LAN I / F 18 (S13). The frequency information includes the frequency of the radio wave currently being received by the radio 20. Next, based on this reception frequency, the capacitor switching circuit 11a selects the capacitance of the capacitor (S14).

  When the reception frequency is included in the TV broadcast band (S14: TV), the capacity for the TV broadcast band is selected. That is, only the switch SW1 is turned on and the capacitor C1 is selected (S15).

  When the reception frequency is included in the FM broadcast band (S14: FM), the FM broadcast band capacity is selected. That is, only the switch SW2 is turned on, and the capacitor C2 is selected (S16).

  When the reception frequency is included in the AM broadcast band (S14: AM), the capacity for the AM broadcast band is selected. That is, only the switch SW3 is turned on and the capacitor C3 is selected (S17).

  When the reception frequency is not included in any of the above-described broadcast bands (including when the radio 20 is in an off state) (S14: Default), the default capacity is selected as described above (S18).

  The above-mentioned configuration is “a variable capacitance circuit includes a plurality of capacitors connected in parallel, and a capacitance setting circuit selects at least one of the plurality of capacitors and sets the capacitance of the variable capacitance circuit. Things ". With this configuration, generation of radio noise for a plurality of frequency bands can be reduced. A plurality of capacitors may be selected. At this time, a plurality of switches are turned on. Thereby, generation | occurrence | production of the radio noise which arises in still more frequency bands can be reduced.

  FIG. 3 shows another example of the configuration of the electronic device 1. In addition, since this structure is a modification of FIG. 1, the same code | symbol is provided about the structure similar to FIG. 1, and detailed description here is omitted. The variable capacitance circuit 15 is provided between the signal input line 17 (signal line of the present invention) connected to the input port P1 of the microcomputer 11 and the ground (GND). The signal input line 17 is connected to a switch (which may be a sensor) SW11 provided outside the ECU 10 via a current limiting resistor R3 and a backflow preventing diode D1. With this configuration, the microcomputer 11 detects the state of the switch SW11.

  The signal input line 17 is connected to a sampling circuit 13 including a timer or a counter via a resistor R2. The sampling circuit 13 connects / cuts off the signal line 17, for example, at a predetermined timing based on a command from the microcomputer 11 so that the state of the switch SW11 can be input to the input port P1.

  The variable capacitance circuit 15 has a plurality of capacitors (C4 to C6) connected in parallel. One end of each capacitor is connected to the signal input line 17, and the other end is grounded via a switch (SW4 to SW6). (GND). As in FIG. 1, the length and thickness of each wiring pattern on the circuit board 19 between the capacitors (C4 to C6) to the switches (SW4 to SW6) to GND are preferably substantially the same.

  The capacitor C4 is set to have a capacitance so as to reduce radio noise generated in the TV broadcast band. Similarly, the capacitor C5 is set to reduce radio noise generated in the FM broadcast band, and the capacitor C6 is set so as to reduce radio noise generated in the AM broadcast band.

  The capacity switching control process is the same as in FIG. 2 except for the following points.

  When the reception frequency is the TV broadcast band (S14: TV), the capacity for the TV broadcast band is selected. That is, only the switch SW4 is turned on, and the capacitor C4 is selected (S15).

  When the reception frequency is the FM broadcast band (S14: FM), the FM broadcast band capacity is selected. That is, only the switch SW5 is turned on, and the capacitor C5 is selected (S16).

  When the reception frequency is the AM broadcast band (S14: AM), the capacity for the AM broadcast band is selected. That is, only the switch SW6 is turned on and the capacitor C6 is selected (S17).

  When the reception frequency is not included in any of the above-described broadcast bands (including when the radio 30 is off) (S14: Default), only the switch SW4 is turned on and the capacitor C4 is selected as the default capacity. (S18).

  In FIG. 3, the variable capacitance circuit 12a of the power supply circuit 12 is not shown, but the variable capacitance circuit 12a may not be included.

  Moreover, it is good also as a structure containing the vehicle side communication apparatus 41 of the keyless entry system 40, or the vehicle side apparatus (not shown) of a tire pressure monitoring system similarly to FIG. In this case, the variable capacitance circuit 15 includes the capacitor C10 and the switch SW10. In the state of Step S14: Default, only the switch SW10 is turned on and the capacitor C10 is selected. Further, the capacitance may be set so that the capacitor C4 can also serve as the capacitor C10.

  FIG. 4 shows another example of the configuration of the electronic device 1. Since this configuration is a modification of FIG. 3, the same reference numerals are given to the same configurations as those in FIG. 3, and detailed descriptions thereof are omitted here. The main difference from FIG. 3 is the configuration of the variable capacitance circuit.

  The microcomputer 11 includes a pattern switching circuit 11c (capacitance setting circuit of the present invention, details will be described later) instead of the capacitor switching circuit 11a.

  The variable capacitance circuit 16 includes a capacitor C7 having one terminal connected to the signal input line 17, a wiring pattern (16a, 16b, 16c) connected to the other terminal of the capacitor C7, and these wiring patterns and ground ( GND) and switches (SW7 to SW9). These wiring patterns are preferably arranged adjacent to each other, and the length and thickness are all different. For this reason, the line capacity of each wiring pattern is different, and the combined capacity with the capacitor C7 when the switch is closed is also different. Therefore, the same operation as the configuration in which three capacitors having different capacities are connected in parallel as shown in FIG. It can be performed.

  The above-described configuration is as follows: “The variable capacitance circuit includes a single capacitor and a plurality of wiring patterns formed on a circuit board and having different lengths and widths for connecting the capacitor and the ground. In addition, the capacitance setting circuit selects at least one of the wiring patterns and sets the capacitance of the variable capacitance circuit ”. With this configuration, it is possible to reduce the generation of noise for a plurality of frequency bands.

  The capacity switching control process is the same as in FIG. 2 except for the following points.

  When the reception frequency is the TV broadcast band (S14: TV), the capacity for the TV broadcast band is selected. That is, only the switch SW7 is turned on, and the wiring pattern 16a is selected (S15).

  When the reception frequency is the FM broadcast band (S14: FM), the FM broadcast band capacity is selected. That is, only the switch SW8 is turned on and the wiring pattern 16b is selected (S16).

  When the reception frequency is the AM broadcast band (S14: AM), the capacity for the AM broadcast band is selected. That is, only the switch SW9 is turned on, and the wiring pattern 16c is selected (S17).

  When the reception frequency is not included in any of the above-described broadcasting bands (including when the radio 30 is in an off state) (S14: Default), only the switch SW7 is turned on as a default capacity, and the wiring pattern 16a is selected. (S18).

  In FIG. 4, the variable capacitance circuit 12a of the power supply circuit 12 is not shown, but the variable capacitance circuit 12a may not be included.

  Moreover, it is good also as a structure containing the vehicle side communication apparatus 41 of the keyless entry system 40, or the vehicle side apparatus (not shown) of a tire pressure monitoring system similarly to FIG. In this case, a wiring pattern and a switch (both not shown) corresponding to the operating frequency of the vehicle side communication device 41 and the like are connected to the capacitor C7, and in the state of Step S14: Default, only the switch is turned on. . Further, the length or area may be set so that the wiring pattern 16a can also serve this role.

  3 and 4, the variable capacitance circuit (15, 16) is connected to the signal line of the input port (P1) of the microcomputer 11, but is connected to the signal line (not shown) of the output port of the microcomputer 11. May be.

  The configurations of the variable capacitance circuits 15 and 16 may be used for the variable capacitance circuit 12a (see FIG. 1) of the power supply circuit 12. At this time, one end (the one not connected to the wiring pattern) of the capacitor C7 is connected to the power supply line 12b.

  3 and 4 described above is “a signal line is a signal input line for inputting a signal to an electronic component”. With this configuration, the generation of noise from the signal input line and its peripheral circuits with respect to frequencies used by other devices (for example, harmonics generated by the oscillation circuit 11b that are close to the frequencies being used) is reduced. Can do.

  Hereinafter, a second embodiment of the electronic device of the present invention will be described with reference to the drawings. Since this embodiment is a modification of the above-described first embodiment, the same reference numerals are given to the same configurations as those in the first embodiment, and detailed description thereof is omitted here.

  Conventionally, radio noise evaluation is performed under certain environmental conditions (power supply voltage, ambient temperature, number of evaluations, product lot, etc.), and based on the results, circuit board pattern change, component change, component (capacitor) As a result, measures against radio noise were taken. In this method, the capacitance of the capacitor changes due to power supply voltage fluctuations, ambient temperature changes, component performance variations due to product lots, and secular changes, and radio noise cannot be removed appropriately.

  Therefore, in addition to the configuration in which the electronic device is provided with a capacitance setting circuit that switches the capacitor capacitance for noise reduction as in the first embodiment described above, a circuit that selects a capacitor capacitance that minimizes the noise level is provided in another device. to add.

  That is, the second embodiment states that “the electronic component mounted on the circuit board, the variable capacitance circuit provided between the signal line connected to the electronic component and the ground, and the capacitance of the variable capacitance circuit are set. Capacity setting circuit, information acquisition circuit for acquiring operation state information reflecting the operation state of other devices, and setting state information reflecting the setting value of the variable capacitance circuit based on the acquired operation state information An information output circuit, and after the information output circuit outputs the setting state information, the information acquisition circuit acquires a recommended value of the setting value from another device, and the capacity setting circuit, based on the acquired recommended value, Set the capacitance of the variable capacitance circuit ”.

  With the above configuration, it is possible to set an optimum capacity without being affected by variations in capacitor performance, ambient temperature, power supply voltage, and secular change, and more reliably reduce radio noise.

  FIG. 5 shows a configuration of the electronic device 1. FIG. 5 is a modification of FIG. 1 and differs in the configuration of the radio 20 (the keyless entry system 40 is not shown). In the first embodiment, the radio 20 only outputs the radio state information to the electronic device via the in-vehicle LAN 30, but in this embodiment, the setting value of the capacity of the variable capacitance circuit 12a is obtained from the electronic device 1. The recommended value of the capacitance of the variable capacitance circuit 12a is output from the noise amount measured at that time.

  The radio 20 includes a noise amount measurement / storage circuit 21 (measurement circuit and storage circuit of the present invention), a noise amount measurement / storage circuit for measuring and storing a noise amount (for example, S / N ratio) mixed in the reception frequency. Based on the measured noise amount of 21, based on the operation of the capacitor selection circuit 22 (selection circuit of the present invention) for selecting the recommended value of the capacitance of the variable capacitance circuit 12 a, and the tuning switch (switch) 24 by the user, A well-known channel selection circuit 23 that tunes the reception frequency to a frequency selected by the user, and a LAN I / F 25 (acquisition circuit, output circuit of the present invention) that is a communication interface circuit of the in-vehicle LAN 30 are included.

  FIG. 6 shows another example of the configuration of the electronic device 1. FIG. 6 is a modification example of FIG. 3, and a known spectrum analyzer (hereinafter also abbreviated as “sparener”) 50 for measuring the frequency characteristics of the device mounted on the vehicle is connected to the ECU 10. Is. The spectrum analyzer 50 measures the noise amount measured by the noise amount measurement / storage circuit 51 (measurement circuit or storage circuit of the present invention) for measuring the amount of noise mixed in the frequency being measured. Based on the capacitor capacity selection circuit 52 (selection circuit of the present invention) that selects the recommended value of the capacitance of the variable capacitance circuit 15 and the frequency setting circuit that sets the measurement frequency based on the operation of the operation SW (switch) 54 by the user. 53, includes a LAN I / F 55 (acquisition circuit, output circuit of the present invention) which is a communication interface circuit of the in-vehicle LAN 30.

  FIG. 7 shows another example of the configuration of the electronic device 1. FIG. 7 is a modification of FIG. 4 in which a radio 20 having the same configuration as in FIG. 5 is connected to the ECU 10.

  The radio 20 and the spectrum analyzer 50 described above “When another device acquires the setting state information, the measurement circuit that measures the level of noise mixed in the other device, and the setting state information. A storage circuit that stores the measured noise level in association with the setting state information, a selection circuit that compares the stored noise level and selects a recommended setting value, and an output circuit that outputs the recommended value. It's a "preparation". An optimum capacity setting value in the variable capacity circuit can be selected in accordance with the operating state (that is, the selected frequency) of the radio 20 and the spectrum analyzer 50.

  Each circuit of the above-described radio 20 and spectrum analyzer 50 may include a CPU, various memories, and the like, and may be configured in hardware as one or a plurality of ICs or ASICs, or part or all of them may be software. It may be built on a memory in terms of software.

  The capacity switching control process executed by the microcomputer 11 in the configurations of FIGS. 5 to 7 will be described with reference to FIG. The radio 20 or the spectrum analyzer 50 corresponds to “another device” of the present invention, and is therefore collectively referred to as “device” here. The capacitor switching circuit 11a and the pattern switching circuit 11c in FIGS. 5 to 7 are collectively referred to as “switching circuit”. In addition, the variable capacitance circuits 12a, 15, and 16 in FIGS. 5 to 7 are collectively referred to as “variable capacitance circuits”.

  First, operation state information reflecting the operation state of the apparatus is acquired from the apparatus via the in-vehicle LAN 30 and the LAN I / F 18 (S31). Next, based on the acquired operation state information, it is determined whether or not the apparatus is operating using at least one of the following.

When the operation state information includes the on / off state of the radio 20 or the spectrum analyzer 50, it is determined based on this information whether the operation is in progress.
When the operation state information includes the state of the tuning frequency of the radio 20, when this frequency is included in the frequency band of each broadcast described above, it is determined that the operation is in progress.
When the operation state information includes the state of the measurement frequency of the spectrum analyzer 50, when this frequency is included in the measurement range of the spectrum analyzer 50, it is determined that the spectrum analyzer 50 is operating.

  When the device is not operating (S32: No), the switching circuit switches the capacitor so that the capacitor capacity of the variable capacitance circuit becomes a default value (S41). In the configuration of FIG. 5, only the switch SW10 is turned on, in the configuration of FIG. 6, only the switch SW4 is turned on, and in the configuration of FIG. 7, only the switch SW7 is turned on.

On the other hand, when the device is operating (S32: Yes), it is determined whether or not the state of the device has changed.
The apparatus is not operating according to the operation state information acquired last time, but when the apparatus is operating according to the operation state information acquired last time, it is determined that the state has changed.
• When the tuning frequency or measurement frequency changes, it is determined that the state has changed.

  When there is no change in the state of the apparatus (S33: No), this process is terminated. That is, the current state of the variable capacitance circuit is maintained. On the other hand, when there is a change in the state of the apparatus (S33: Yes), the switching circuit switches the capacitor capacity of the variable capacitance circuit to the first set value (for example, the minimum value) (S34). In the configuration of FIG. 5, only the switch SW1 is turned on, in the configuration of FIG. 6, only the switch SW4 is turned on, and in the configuration of FIG. 7, only the switch SW7 is turned on. Then, the setting state information reflecting the setting value is output to the apparatus via the LAN I / F 18 and the in-vehicle LAN 30 (S35).

  Instead of the setting value, a parameter that can specify the capacitor capacity of the variable capacitance circuit, such as the switching state of the switch of the switching circuit, may be output as the setting state information.

Next, it is determined whether or not a condition (switching condition) for switching the set value is satisfied by using at least one of the following.
-It is determined that the switching condition is satisfied when a predetermined time has elapsed since the set value was output.
When a setting value switching request is acquired from the apparatus after outputting the setting value, it is determined that the switching condition is satisfied.

  When the switching condition is satisfied (S36: Yes), it is determined whether or not all set values of the capacitor capacity of the variable capacitance circuit have been output. In the configuration of FIG. 5, the switches SW1 to SW3 are switched to determine whether or not the three set values of the capacitors C1 to C3 are sequentially output. The capacitor C10 may be included in the set value. Similarly, in the configurations of FIGS. 6 and 7, the switches SW4 to SW6 or the switches SW7 to SW9 are switched to determine whether or not the set values of the capacitors C4 to C6 or the capacitors C7 to C9 are sequentially output.

  When all set values are not output (S37: No), the switching circuit switches the capacitor capacity of the variable capacitance circuit to the next set value (S38), and outputs the set value to the apparatus (S35). This configuration is: “The capacitance setting circuit changes the setting value of the variable capacitance circuit at a predetermined timing, and the output circuit reflects the setting value in the setting state information every time the setting value changes. Output ". With this configuration, the capacitor capacity of the variable capacitance circuit can be sequentially switched and output to another device.

  On the other hand, when all set values have been output (S37: Yes), the apparatus enters a waiting state for obtaining a recommended value of the capacitor capacity (any one of the output set values) from the apparatus. When the recommended value is acquired (S39: Yes), the switching circuit switches the capacitor capacity of the variable capacitance circuit to the recommended value (S40).

  After outputting all the setting values, or when outputting the last setting value, information indicating that all setting state information has been output may be output.

  With reference to FIG. 9, the recommended value determination process executed in the device (that is, the radio 20 or the spectrum analyzer 50) will be described. The noise amount measurement / storage circuits 21 and 51 are collectively referred to as “noise amount measurement / storage circuit”. The capacitor capacity selection circuits 22 and 52 are collectively referred to as “capacitor capacity selection circuit”.

  First, when there is a change in the state of the apparatus (that is, during operation), or when the tuning frequency or measurement frequency changes (S51: Yes), this state change is reflected in the operation state information and output to the ECU 10. (S52).

  Thereafter, the setting state information from the ECU 10 is waited, and when the setting state information is acquired (S53: Yes), the noise amount is measured by the noise amount measurement / storage circuit, and the measurement result is stored in association with the setting state information ( S54).

Next, it is determined whether a comparison condition for comparing the measurement results is satisfied. This determines whether or not all the setting state information has been acquired from the ECU 10, and uses at least one of the following.
When a predetermined number (3 in the configurations of FIGS. 5 to 7) of setting state information is received, it is determined that the comparison condition is satisfied.
When it is determined that all the setting state information has been output from the ECU 10, it is determined that the comparison condition is satisfied.

  When the comparison condition is not satisfied (S55: No), the process returns to step S53, and the next setting state information acquisition wait state is entered.

  On the other hand, when the comparison condition is satisfied (S55: Yes), the acquired and stored noise amounts are compared (S56). Then, the setting value (or switch switching state) reflected in the setting state information associated with the smallest of these noise amounts is determined as the recommended value (S57). Finally, this recommended value is output to the ECU 10 (S58).

  In each embodiment described above, a plurality of ECUs may be connected to other devices in addition to the ECU 10. In this case, each of the above-described processes (FIGS. 2 and 8) is executed in each of the plurality of ECUs. Further, for example, a capacity may be set by combining a plurality of switches among the switches SW1 to SW3.

  Although the embodiments of the present invention have been described above, these are merely examples, and the present invention is not limited to these embodiments, and the knowledge of those skilled in the art can be used without departing from the spirit of the claims. Various modifications based on this are possible.

1 Electronic device 10 ECU
11 Microcomputer (electronic parts, capacity setting circuit)
11a Capacitor switching circuit (capacitance setting circuit)
12a, 15, 16 Variable capacitance circuit 12b Power supply line (signal line)
17 Signal input line (signal line)
11c Pattern switching circuit (capacitance setting circuit)
16a, 16b, 16c Wiring pattern 18 LAN I / F (information acquisition circuit, information output circuit)
19 Circuit board 20 Radio (Radio receiver)
21 Noise measurement / memory circuit (measuring circuit, memory circuit)
22 Capacitor capacity selection circuit (selection circuit)
23 Channel selection circuit 24 Channel selection SW (switch)
25 LAN I / F (acquisition circuit, output circuit)
30 in-car LAN
40 Keyless entry system 41 Vehicle side communication device 50 Spectrum analyzer 51 Noise amount measurement / storage circuit (measurement circuit, storage circuit)
52 Capacitor capacity selection circuit (selection circuit)
53 Frequency setting circuit 54 Operation SW (switch)
55 LAN I / F (acquisition circuit, output circuit)
C1 to C10 Capacitor SW1 to SW10 Switch GND Ground

Claims (9)

An electronic control device, and another device provided separately from the electronic control device,
The electronic control device
Electronic components mounted on a circuit board;
A variable capacitance circuit provided between a signal line connected to the electronic component and the ground, and configured so that a capacitance between the same signal line and the ground can be set to a plurality of values;
An information acquisition circuit for acquiring operation state information reflecting the operation state of the other device;
A circuit for setting the capacitance of the variable capacitance circuit, and when the operation state information is information indicating that the operation state of the other device has changed, the setting value of the variable capacitance circuit is A capacitance setting circuit that sequentially changes between the plurality of values;
An information output circuit that outputs setting state information reflecting the setting value each time the setting value of the variable capacitance circuit changes;
With
The other device is
An acquisition circuit for acquiring the setting state information;
A measurement circuit for measuring the level of noise mixed in the other device;
A storage circuit for storing the noise level measured when the setting state information is acquired in association with the setting state information;
A selection circuit for comparing the stored noise levels and selecting a recommended value of the set value;
An output circuit for outputting the recommended value;
With
After the information output circuit outputs the setting state information, the information acquisition circuit acquires a recommended value of the setting value from the other device,
The electronic device is characterized in that the capacitance setting circuit sets the capacitance of the variable capacitance circuit based on the acquired recommended value.   The electronic device according to claim 1, wherein the operation state information includes a frequency being used by the other device.   The electronic device according to claim 1, wherein the signal line is a power supply line for supplying power to the electronic component.   4. The electronic device according to claim 1, wherein the signal line is a signal input line for inputting a signal to the electronic component. 5.   The variable capacitance circuit includes a plurality of capacitors connected in parallel,
  5. The electronic device according to claim 1, wherein the capacitance setting circuit selects at least one of the plurality of capacitors and sets a capacitance of the variable capacitance circuit. 6.   The variable capacitance circuit is:
  One capacitor and
  A plurality of wiring patterns formed on the circuit board and having different lengths and widths for connecting the capacitor and the ground; and
  Including
  6. The electronic device according to claim 1, wherein the capacitance setting circuit selects at least one of the wiring patterns and sets a capacitance of the variable capacitance circuit. 7.   The electronic device according to claim 1, wherein the other device is a radio receiver.   The said other apparatus is a vehicle side communication apparatus mounted in the vehicle in the keyless entry system which performs the predetermined | prescribed function of a vehicle based on the radio | wireless communication with the portable device which a user possesses. Electronic equipment.   The electronic device according to claim 1, wherein the other device is a spectrum analyzer.

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