JP2022110901A - Electronic apparatus - Google Patents

Abstract

To provide an electronic apparatus that appropriately detects an abnormal state resulting from extraneous noise.SOLUTION: A circuit board 1 comprises: a mounting circuit 11 that performs a predetermined operation; a wiring pattern 12 that is closer to the outer periphery of the circuit board 1 than the mounting circuit 11; and a connector 13 that is connected with a first electric wire 2a connected with a ground point of the electronic apparatus and electrically connects the wiring pattern 12 and the first electric wire 2a to each other. A detection circuit 14 detects voltage of the wiring pattern 12, and outputs the voltage filtered with predetermined frequency characteristics as output voltage. A controller 3 detects an abnormal state of the circuit board 1 based on the output voltage.SELECTED DRAWING: Figure 1

Description

The present invention relates to electronic equipment.

In some liquid crystal display devices, a conductive pattern is formed on the periphery of a printed wiring board on which a drive circuit for the liquid crystal display is arranged, and the conductive pattern is grounded via a connector (see, for example, Patent Document 1).

Japanese Patent Application Laid-Open No. 2001-100233

Although the above technology suppresses the effects of external noise caused by static electricity discharge, etc., depending on the noise intensity, there is a possibility that the circuit on the substrate will malfunction and malfunction, but the operation will continue. As a result, it is difficult for the user to grasp the occurrence of the abnormality and to grasp the cause of the malfunction until the user's desired operation result cannot be obtained due to the malfunction.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to obtain an electronic device that appropriately detects an abnormal state caused by external noise.

An electronic device according to the present invention includes a circuit board, a detection circuit, and a controller. The circuit board is connected to a mounted circuit for performing a predetermined operation, a wiring pattern on the circuit board on the outer peripheral side of the mounted circuit, and a first wire connected to a ground point of the electronic device, and the wiring pattern is connected to the wiring pattern. and a connector for electrically connecting the first electric wire. The detection circuit detects the voltage of the wiring pattern and outputs the voltage filtered with a predetermined frequency characteristic as an output voltage, and the controller detects the abnormal state of the circuit board based on the output voltage. to detect

According to the present invention, it is possible to obtain an electronic device that appropriately detects an abnormal state caused by external noise.

The above and other objects, features and advantages of the present invention will become further apparent from the following detailed description together with the accompanying drawings.

FIG. 1 is a diagram showing the configuration of an electronic device according to an embodiment of the invention. FIG. 2 is a circuit diagram showing a configuration of detection circuit 14 in FIG. FIG. 3 is a cross-sectional view for explaining an example of a location where external noise is assumed to invade. FIG. 4 is a flow chart for explaining the operation of the controller 3 in FIG.

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a diagram showing the configuration of an electronic device according to an embodiment of the invention. The electronic device shown in FIG. 1 includes a circuit board 1 , a harness 2 connected to the circuit board 1 , and a controller 3 . The circuit board 1 is a printed wiring board. The harness 2 includes a plurality of electric wires (electric wires 2a, 2b, etc.). The controller 3 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), a non-volatile storage device, an I/O interface, etc., and outputs a predetermined control program from the ROM or non-volatile storage device. Various processes are executed by reading out and executing by the CPU.

The circuit board 1 includes a mounted circuit 11 that performs a predetermined operation, a wiring pattern (hereinafter also referred to as a ground pattern) 12 on the circuit board 1 on the outer peripheral side of the mounted circuit 11 , and a connector 13 . The connector 13 is connected to the first wire 2a connected to the ground point of the electronic device (here, a predetermined position in the metal frame inside the electronic device), and connects the wiring pattern 12 and the first wire 2a. Connect electrically. Note that the ground pattern 12 has a missing portion 12a to prevent loop current.

The detection circuit 14 detects the voltage of the ground pattern 12 and outputs the voltage filtered with a predetermined frequency characteristic as an output voltage. In this embodiment, the detection circuit 14 is mounted on the circuit board 1 and its output voltage is applied to the connector 13 via the wiring pattern 15 .

FIG. 2 is a circuit diagram showing a configuration of detection circuit 14 in FIG.

For example, as shown in FIG. 2, the detection circuit 14 comprises a high cut filter 14a comprising a resistor R and a capacitor C, and a Zener diode ZD. The frequency characteristic of the high-cut filter 14a is determined by the resistance value of the resistor R and the capacitance value of the capacitor C, and is set so that a predetermined short-term voltage fluctuation of the ground pattern 12 is ignored. Zener diode ZD also eliminates surges (overvoltage) to controller 3 .

For example, the ground (ground GND in FIG. 2) of the detection circuit 14 is electrically connected to the first wire 2a at the connector 13 via the wiring pattern 16. FIG. The ground of the detection circuit 14 (the ground GND in FIG. 2) is not electrically connected to the ground pattern 12 on the circuit board 1, but is connected via the connector 13 with a wire different from the first wire 2a. It may be connected to a ground point.

Also, the connection point 12b between the ground pattern 12 and the connector 13 is set at any position in the ground pattern 12 between the assumed invasion point 21 of external noise and the voltage detection point 12c by the detection circuit 14. . As a result, the detection circuit 14 detects the influence of the external noise on the ground pattern 12 remaining after the current due to the external noise flows from the connection point 12b to the ground point at the voltage detection point 12c.

FIG. 3 is a cross-sectional view for explaining an example of an assumed location 21 of invasion of external noise.

For example, the electronic device has an operation panel section, and as shown in FIG. When static electricity discharge is likely to occur, a location within the range of a predetermined distance from the gap in the ground pattern 12 is set as the assumed attack location 21 .

Returning to FIG. 1, the controller 3 detects an abnormal state of the circuit board 1 (that is, an abnormal state caused by external noise) based on the output voltage. In this embodiment, the controller 3 is mounted on a circuit board different from the circuit board 1 and detects the output voltage described above via a second wire 2 b connected to the connector 13 . The ground of the controller 3 is electrically connected to the ground point mentioned above via the circuit board and another wire.

In this embodiment, the controller 3 stops the operation of the electronic device and displays a warning message on a predetermined display device (for example, displayed on the display panel of the operation panel).

This warning message is, for example, a message prompting the user to turn off the main power and turn it on again. In other words, since the abnormality of the circuit board 1 does not recover naturally, the user is urged to turn off the power once and restart the electronic device.

Next, the operation of the electronic device will be described. FIG. 4 is a flow chart for explaining the operation of the controller 3 in FIG.

When the electronic device starts operating (step S1), the controller 3 resets the counter N to 0 (step S2), and monitors the output voltage of the detection circuit 14 (that is, the detected voltage level of the ground pattern 12). , and determines whether the output voltage exceeds a predetermined threshold (step S3). Note that the counter N is a counter for measuring the duration that the output voltage exceeds a predetermined threshold.

When it is determined that the output voltage does not exceed the predetermined threshold, the controller 3 determines that the circuit board 1 is in a normal state, continues the operation of the electronic device (step S4), and resets the counter N to 0. (step S5).

Then, the controller 3 determines whether or not an operation end event of the electronic device such as a predetermined user operation is detected (step S6), and returns to step S3 if an operation end event is not detected. On the other hand, when the operation end event is detected, the controller 3 ends the operation of the electronic device.

On the other hand, if it is determined in step S3 that the output voltage exceeds the predetermined threshold, the controller 3 determines that the circuit board 1 is in an abnormal state and stops the operation of the electronic device (step S7).

Then, the controller 3 determines whether or not the counter N has reached 2 (that is, whether or not the duration of the abnormal state has reached 12 seconds) (step S8). If so, the counter N is incremented by 1 (step S9), and after waiting for a predetermined time (here, 6 seconds) (step S10), the process returns to step S3. Note that the threshold value of the counter N is 2 here, but other numerical values may be used.

Further, when it is determined in step S8 that the counter N has reached 2, the controller 3 displays the above-described warning message on a predetermined display device (step S11), and with the operation of the electronic device stopped, , continue its display.

As described above, according to the above-described embodiment, the circuit board 1 includes the mounted circuit 11 that performs a predetermined operation, the wiring pattern 12 on the circuit board 1 on the outer peripheral side of the mounted circuit 11, and the electronic device. A connector 13 is provided that is connected to the first electric wire 2a connected to the ground point and electrically connects the wiring pattern 12 and the first electric wire 2a. The detection circuit 14 detects the voltage of the wiring pattern 12 and outputs a voltage filtered with a predetermined frequency characteristic as an output voltage, and the controller 3 detects an abnormal state of the circuit board 1 based on the output voltage. To detect.

As a result, an abnormal state of the circuit board 1 caused by external noise is properly detected and notified based on the voltage fluctuation of the wiring pattern 12 caused by the discharge of static electricity.

Various changes and modifications to the above-described embodiments will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the spirit and scope of its subject matter and without diminishing its intended advantages. It is therefore intended that such changes and modifications be covered by the claims.

For example, the electronic device according to the above embodiments may be an image forming apparatus such as a printer or a multifunction device.

The present invention is applicable, for example, to electronic equipment.

REFERENCE SIGNS LIST 1 circuit board 2a first wire 2b second wire 3 controller 11 mounting circuit 12 wiring pattern 13 connector 14 detection circuit 14a high cut filter

Claims (7)

In electronic equipment,
a circuit board;
a detection circuit;
with a controller,
The circuit board is connected to a mounted circuit that performs a predetermined operation, a wiring pattern on the circuit board on the outer peripheral side of the mounted circuit, and a first wire connected to a ground point of the electronic device, and the wiring pattern is connected to the circuit board. and a connector that electrically connects the first wire,
the detection circuit detects the voltage of the wiring pattern and outputs the voltage filtered with a predetermined frequency characteristic as an output voltage;
the controller detecting an abnormal state of the circuit board based on the output voltage;
An electronic device characterized by: The detection circuit is mounted on the circuit board and applies the output voltage to the connector;
The controller is mounted on a circuit board different from the circuit board, and detects the output voltage via a second wire connected to the connector;
The electronic device according to claim 1, characterized by: A connection point between the wiring pattern and the connector is set at any position between a point where an invasion of external noise is assumed and a point where the voltage is detected by the detection circuit in the wiring pattern. The electronic device according to claim 1. 2. The electronic device according to claim 1, wherein the detection circuit includes a high-cut filter, and outputs the voltage filtered by the high-cut filter as an output voltage. The ground of the detection circuit is not electrically connected to the wiring pattern on the circuit board, but is connected to the ground point through the connector by an electric wire different from the first electric wire. The electronic device according to claim 1, wherein: 2. The electronic device according to claim 1, wherein when the output voltage exceeds a predetermined threshold continuously for a predetermined time, the controller stops the operation of the electronic device and displays a warning message on a predetermined display device. machine. The electronic device has an operation panel,
The circuit board is built in the operation panel section;
The electronic device according to claim 1, characterized by:

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