JP6499520B2 - Electronic device that receives multiple small signals - Google Patents

Description

  The present invention relates to an electronic device, and more particularly to an electronic device that operates by receiving a plurality of minute signals from a sensor or the like.

  For example, in an electronic control unit (ECU, Electronic Control Unit) that performs engine control in an automobile, fuel injection, which is a control target, is based on various detection signals such as engine speed, crank angle, intake air amount, air temperature, atmospheric pressure, and the like. The load of the actuator is controlled. These detection signals are output from different sensors and input to the electronic control unit. In the electronic control unit, for example, these sensor inputs are converted into digital signals by AD converters, respectively, and then subjected to predetermined arithmetic processing. A digital signal obtained as a result of the arithmetic processing is converted into an analog signal by a DA converter, and a load is driven by a load driving circuit based on the analog signal.

  In this case, in order to perform load control correctly, all of the plurality of detection signals as described above must correctly convey the state of each detection target, and if even one wrong signal is input. The load cannot be controlled correctly. For example, when the ground potential of each sensor that outputs a detection signal is different from the potential of the analog ground terminal of the AD converter, the AD converter cannot correctly receive the detection signal from these sensors. The converted digital signal (or digital value) does not correctly reflect the state of each detection target of these sensors.

  Conventionally, in such an electronic device that processes a minute analog signal and a digital signal, an analog signal ground pattern and a digital signal ground pattern are arranged on a circuit board on which circuit components constituting the electronic circuit are mounted. Are formed in a so-called solid pattern (spread surface pattern) instead of a strip-like (linear) pattern, and between the analog signal ground pattern and the digital signal ground pattern. The space is locally connected only at a predetermined limited portion. As a result, each ground pattern has a solid pattern that reduces the impedance of the pattern, thereby preventing local potential fluctuations within the pattern and suppressing the occurrence of non-uniform potential distribution. Between the pattern and the digital signal ground pattern, the impedance is increased to some extent by the local connection of the limited portion described above, so that the potential fluctuation in one ground pattern has an influence on the other ground pattern. Reduced.

  In general, each ground terminal of a plurality of sensors and an analog ground terminal of an AD converter, for example, are connected to an arbitrary position of a solid pattern constituting the analog signal ground pattern on the circuit board. Thus, the potential of each ground terminal of the plurality of sensors is made equal to the potential of the analog ground terminal of the AD converter via the solid pattern so that the detection signal from each sensor can be correctly converted into a digital value. Yes.

  However, when it is necessary to detect the state of the detection target with extremely high accuracy, the reception accuracy of the detection signal received by the AD converter from the sensor is small even if there is a slight local potential variation in the analog signal ground pattern. Can result in control errors. Such slight local potential fluctuations occur, for example, through local connections between ground patterns, and also can be easily generated as digital processing speeds up. It can also be generated by radiation noise from the pattern reaching the analog signal ground pattern by propagating in the housing of the apparatus.

  In addition, such a local potential fluctuation in the ground pattern is caused by an external device that comes from outside the housing of the device itself in an electronic device mounted in an environment that generates large radiation noise, such as in an automobile engine room. In electronic devices that are also caused by radiation noise and that control loads that require large currents and / or voltages such as solenoid actuators, circuit components (for example, switching circuits and load drives) mounted inside the housing of the device itself It can also be caused by noise generated from components constituting the circuit.

  In view of the above background, in an electronic apparatus to which a plurality of minute signals or small analog signals such as sensors are input, it is desired to realize a stable operation by keeping a ground potential as a reference potential common to each small analog signal input. It is rare.

One aspect of the present invention is an electronic device that has a circuit board on which an electronic circuit is mounted and operates by receiving a plurality of analog signals. The circuit board includes at least a reference for each type of signal. A plurality of ground patterns for applying a potential are formed, and circuit components to which the plurality of input analog signals are input are mounted on the circuit board, and the analog signal ground terminals of the circuit components are The ground lines of the plurality of input analog signals connected to one of the plurality of ground patterns do not pass through an electrical component and do not pass through any of the plurality of ground patterns. An electronic device connected to the analog signal ground terminal of the circuit component.
According to another aspect of the present invention, each of the ground lines of the plurality of input analog signals is connected to the analog signal ground of the circuit component via a linear conductor pattern formed on the circuit board. Connected to the terminal.
According to another aspect of the present invention, the plurality of ground patterns are electrically insulated from each other on the circuit board, or are connected to each other in a direct current manner at a local portion.
According to another aspect of the invention, the circuit component is an AD conversion circuit or an IC in which the AD conversion circuit is integrated with other digital circuits.
According to another aspect of the present invention, each of the plurality of analog signals is a detection signal supplied from a sensor.
According to another aspect of the present invention, the electronic device is an electronic control device that is mounted on a vehicle and controls the operation of the vehicle.

It is a figure which shows the structure of the electronic device which concerns on one Embodiment of this invention. It is a figure which shows the example of a connection with the electronic apparatus shown in FIG. 1, and another apparatus. It is a figure which shows the structure of the circuit board used for the electronic device shown in FIG. FIG. 4 is a partial detail view of the circuit board shown in FIG. 3.

  Embodiments of the present invention will be described below with reference to the drawings. The electronic device shown here as an embodiment of the present invention is an electronic control device that is mounted on, for example, a vehicle and controls at least one operation of the vehicle. However, the configuration of the electronic device is not limited to this, and can be similarly applied to widely used electronic devices including other uses. In the following description, “connection” means that the connection is electrically DC unless otherwise specified.

FIG. 1 is a diagram illustrating a configuration of an electronic device according to an embodiment of the present invention. FIG. 1A is a front view of the electronic apparatus, FIG. 1B is a top view, and FIG.
The electronic device 10 includes a housing 100 configured by fixing a case 100a and a cover 100b with screws 102a to 102d, and a circuit board 104 accommodated in the housing 100. On the circuit board 104, a plurality of electric circuit components including the circuit component 106 are mounted to constitute an electronic circuit. Further, a connector 108 for connecting an electronic circuit formed by the circuit board 104 to an external device or device is mounted on the circuit board 104 so as to protrude from the housing 100 to the outside.

  In the present embodiment, the circuit component 106 is an IC (semiconductor integrated circuit, integrated circuit) configured to process an analog signal and a digital signal therein. For example, an AD converter or another digital together with the AD converter An IC (signal processor, microcomputer, etc.) in which a circuit (for example, a processor) is integrated. The circuit component 106 includes an analog ground (AGND) terminal 110 to which a reference ground potential for an analog signal to be processed is input, and a digital ground to which a reference ground potential for a digital signal to be processed is input. (DGND) terminal 112.

  The ground potential applied to the analog ground terminal 110 is used as a reference ground potential for analog signal input of an AD converter integrated in the circuit component 106, for example. Note that the circuit component 106 may be provided with a power supply terminal and other signal terminals for inputting and outputting analog signals and digital signals, respectively, but these are not necessary for the description of the present embodiment. The illustration and description of the signal terminals are omitted.

  FIG. 2 is a diagram illustrating an example of connection between the electronic device 10 and another device. For example, the electronic device 10 includes a power supply device 200, four sensors 202, 204, 206, 208, and these sensors 202˜. An actuator 210 that is a control target or a load that is controlled based on a signal from 208 is connected via the connector 108. Here, the sensors 202 to 208 are sensors for detecting, for example, the engine speed, the crank angle, the intake air amount, the air temperature, the atmospheric pressure, and the like, and the actuator 210 opens and closes the intake valve and the fuel injection valve of the engine, for example. Actuator.

  FIG. 3 is a diagram illustrating an example of the configuration of the circuit board 104. In FIG. 3, the back surface of the circuit board 104 on which various ground patterns are formed (therefore, the right side in FIG. 3 corresponds to the left side in FIG. 1B) is shown together with the connector. The circuit board 104 is supplied with a signal ground (SG) pattern 300 for applying a reference ground potential of an analog small signal handled by an electronic circuit configured on the circuit board 104 and a reference ground potential of a digital signal. For example, a logic ground (LG) pattern 302 and a power ground (PG) pattern 304 for providing a reference ground potential of a large voltage or large current signal for driving the actuator 210 are formed. Yes.

  The SG pattern 300 is connected to the ground terminal (not shown) of the external power supply apparatus 200 via the three terminals 306 of the connector 108. Similarly, the LG pattern 302 and the PG pattern 304 are respectively connected to the connector 108. The terminal 308 and 310 are connected to the ground terminal of the external power supply device 200. In the vicinity of the connector 108, the SG pattern 300 and the LG pattern 302 are connected to each other by a connection pattern 312, and the LG pattern 302 and the PG pattern 304 are connected to each other by a connection pattern 314.

  With these connection patterns 312, 314, the SG pattern 300, the LG pattern 302, and the PG pattern 304 are maintained at substantially the same potential in terms of direct current. In this embodiment, since the single power supply device 200 operates, the SG pattern 300, the LG pattern 302, and the PG pattern 304 are connected to each other at least at a ground terminal (not shown) of the power supply device 200. Therefore, the connection patterns 312 and 314 are not necessarily required. However, in the case of an electronic device that operates with a plurality of power supply devices connected, connection between a plurality of ground patterns such as the connection patterns 312 and 314 is required. .

  The digital ground terminal 112 of the circuit component 106 mounted on the front surface of the circuit board 104 is connected to the LG pattern 302 through the via 316, whereby the digital ground terminal 112 has a reference ground potential for a digital signal. Is given from LG pattern 302.

  The analog ground terminal 110 of the circuit component 106 is connected to the land pattern 320 via the via 318. The left and right sides of the land pattern 320 are connected to the SG pattern 300, whereby a reference ground potential for an analog small signal is given from the SG pattern 300 to the analog ground terminal 110.

  Further, the ground lines from the plurality of sensors 202 to 208 (FIG. 2) are supplied with a reference ground potential for an analog small signal via terminals 330, 332, 334, and 336 of the connector 108, respectively. Here, in the prior art, the terminals 330, 332, 334, and 336 are only connected to, for example, a portion on the latest SG pattern 300. On the other hand, in this embodiment, the ground lines from the plurality of sensors 202 to 208 are connected to the land pattern 316 to which the analog ground terminal 110 of the circuit component 106 is connected without passing through the SG pattern 300.

  FIG. 4 is a partial detailed view showing the connection between the terminals 330, 332, 334, and 336 of the connector 108 to which the ground lines from the plurality of sensors 202 to 208 are connected, respectively, and the analog ground pattern 110 of the circuit component 106. is there. The terminals 330, 332, 334, and 336 are connected to the analog ground 110 of the circuit component 106 via the four linear (strip) patterns 400, 402, 404, and 406, respectively, without the SG pattern 300. Connected to the land pattern 320.

  As a result, even if local potential fluctuations occur in the SG pattern 300 in the vicinity of the land pattern 320 due to external radiation noise, noise generated within the apparatus itself, etc., the plurality of sensors 202 to 208 are all in the land pattern 320. The circuit component 106 can receive the detection signals from the sensors 202 to 208 with the ground potential as a common reference potential with high accuracy. Therefore, the electronic device 10 operates stably even if there is a local potential fluctuation induced on the SG pattern 300 due to external radiation noise, noise generated within the device itself, or the like, for example, the actuator 210 or the like. Can be accurately controlled.

  The linear patterns 400 to 406 connecting the terminals 330 to 336 to which the ground lines of the plurality of sensors 202 to 208 are connected and the land pattern 320 to which the analog ground terminal 110 is connected are the terminals 330 to 336, respectively. It is desirable that the dedicated line for connecting to the analog ground terminal 110 is configured so that the ground terminals of other circuit components are not connected.

  In the present embodiment, the four linear patterns 400 to 406 are separated from the terminals 330 to 336 to the land pattern 320 while being separated from each other. However, the present invention is not limited to this, and the four linear patterns 400 to 406 are used. May be connected to each other before reaching the land pattern 320 to be connected to the land pattern 320 as one or a plurality of linear patterns.

  In the present embodiment, the ground patterns 300 to 304 are formed on the back surface of the circuit board 104. However, the present invention is not limited to this, and the ground patterns 300 to 304 are, for example, inner layers of the circuit board 104 configured in multiple layers. It can be formed.

  In addition, the present embodiment is an electronic control device to which a plurality of detection signals are input from an external sensor. However, the configuration of the circuit board 104 described above operates by receiving a plurality of analog small signals from another device, for example. The present invention can be similarly applied to general electronic devices other than the control device.

  As described above, in the electronic apparatus 10 according to this embodiment, the ground lines of the input detection signals (analog small signals) of the plurality of sensors 202 to 208 are formed on the circuit board 104. Since it is connected to the analog ground terminal 110 of the circuit component 106 without passing through any of the ground patterns 300 to 304, the analog ground is not affected by the uneven potential distribution that may occur in the ground patterns 300 to 304. By using the same potential as the terminal 110 as a reference potential, a plurality of input analog signals can be received with high accuracy, and a stable operation as the electronic device 10 can be realized.

  DESCRIPTION OF SYMBOLS 10 ... Electronic device, 100 ... Case, 100a ... Case, 100b ... Cover, 102a, 102b, 102c, 102d ... Screw, 104 ... Circuit board, 106 ... Circuit Components 108, connector 110, analog ground terminal 112, digital ground terminal 200, power supply device 202, 204, 206, 208, sensor 210, actuator 300 ... SG pattern, 302 ... LG pattern, 304 ... PG pattern, 306, 308, 310, 330, 332, 334, 336 ... Terminal, 312, 314 ... Connection pattern, 316, 318 ... via, 320 ... land pattern, 400, 402, 404, 406 ... linear pattern.

Claims (6)

An electronic device having a circuit board on which an electronic circuit is mounted and operating by receiving a plurality of analog signals,
The circuit board is formed with a plurality of ground patterns that give at least a reference potential for each signal type,
On the circuit board, a circuit component to which the plurality of input analog signals are input is mounted, and an analog signal ground terminal of the circuit component is connected to one of the plurality of ground patterns,
Each ground line of the plurality of input analog signals is connected to the analog signal ground terminal of the circuit component without passing through an electrical component and without passing through any of the plurality of ground patterns. ing,
Electronic equipment. Each of the ground lines of the plurality of input analog signals is connected to the analog signal ground terminal of the circuit component via a linear conductor pattern formed on the circuit board.
The electronic device according to claim 1. The plurality of ground patterns are electrically insulated from each other on the circuit board, or are connected to each other in a direct current manner in a local portion.
The electronic device according to claim 1. The circuit component is an AD conversion circuit or an IC in which the AD conversion circuit is integrated with other digital circuits.
The electronic device according to claim 1. Each of the plurality of analog signals is a detection signal supplied from a sensor.
The electronic device according to claim 1. The electronic device is an electronic control device that is mounted on a vehicle and controls the operation of the vehicle.
The electronic device according to claim 1.

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