JP2000121690A - Electronic device self-diagnosis device - Google Patents

Abstract

(57) [Summary] [Problem] Open / close of power supply output terminal for external equipment of electronic equipment
Be able to detect landfall. A voltage comparison circuit detects a potential difference between an input and an output of an external device power supply output circuit, and based on the potential difference, a control circuit such as a microcomputer,
Open / land of the external device power output terminal 15 is detected.
The voltage output circuit 15 for the external device is output by the voltage comparison circuit 13.
The subtle voltage change is detected, so that it is possible to detect whether the power supply output terminal 15 for an external device is open or unconnected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a self-diagnosis device for an electronic device, which can detect whether the power supply output terminal for an external device is open / ground.

[0002]

2. Description of the Related Art Some electronic devices supply power to an external device connected to the electronic device. In such an electronic device, it is necessary to check whether power is supplied to the connected external device without fail. FIG.
1 shows a schematic configuration of an electronic device having a self-diagnosis function of detecting an output terminal state of an external output power supply circuit. In FIG. 2, a control μC which is a microcomputer is used.
The OM 21 is a circuit that controls an electronic device. The external device power output circuit 22 is a circuit that outputs power to an external device based on the power input 24, and has a current limiting circuit. The voltage detection circuit 23 is a power output terminal 2 for an external device.
5 is a circuit for detecting the voltage of No. 5 and converting it into an input signal of the control μCOM 21. The voltage detected by the voltage detection circuit 23 is input to the A / D port of the control μCOM 21, and the ground of the output terminal is detected based on this voltage.

[0003]

However, in the above-described conventional method of detecting the state of an output terminal using a voltage detection circuit, it is easy to detect a ground drop due to a large change in output voltage. It is difficult to determine whether the voltage change is due to a change in the power supply input voltage or to the effect of the load connected to the output terminal.As a result, it is necessary to detect whether the output terminal is open or normally connected. Could not.

An object of the present invention is to solve the above-mentioned conventional problems and to provide a self-diagnosis device for an electronic device capable of detecting opening / closing of a power supply output terminal for an external device of the electronic device. And

[0005]

According to the present invention, in order to achieve the above object, a potential difference between an input and an output of a power supply output circuit for external equipment is detected by a voltage comparison circuit, and a microcomputer is provided based on the potential difference. And the like detect open / ground of the power supply output terminal for the external device. According to the present invention, since a subtle voltage change of the external device power output terminal is detected, it is possible to detect the open / ground of the external device power output terminal.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is directed to a control circuit for controlling an electronic device, a power supply output circuit for an external device with a current limiting function, and an input / output of the power supply output circuit for an external device. A self-diagnosis device for an electronic device, wherein the control circuit detects an open / ground state of the external device power supply output circuit based on the detected potential difference and a detected potential difference. By detecting a subtle voltage change of the power supply output terminal for the external device, it is possible to detect that the output terminal is open / ground.

According to a second aspect of the present invention, the control circuit is a microcomputer, and the potential difference detected by the comparison circuit is input to the A / D port. It is a self-diagnosis device for electronic equipment, and has an effect that it can be applied to many electronic equipment using a microcomputer.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration of a self-diagnosis device for an electronic device according to an embodiment of the present invention. In FIG. 1, a control μCOM11 which is a microcomputer is a circuit for controlling an electronic device. The external device power output circuit 12 is a circuit that outputs power to an external device based on the power input 14 and has a current limiting circuit. The voltage comparison circuit 13 is a circuit that detects a potential difference between the input and output of the external device power supply output circuit 12, that is, a potential difference between the power supply input 14 and the external device power supply output terminal 15, and converts the potential difference into an input signal of the control μCOM 11. The voltage of the external device power output terminal 15 slightly changes depending on the output impedance of the external device power output circuit 12 and the load connected to the external device power output terminal 15. Due to this change, the potential difference detected by the voltage comparison circuit 13 also changes. This potential difference is amplified to control μ
Input to the A / D port of COM11. Thereby, even a slight change in load of the external device power output terminal 15 can be recognized, and it is possible to detect whether the external device power output terminal 15 is open / ground or a normal connection. it can.

[0009]

According to the present invention, as is apparent from the above embodiment, the potential difference between the input and output of the power supply output circuit for an external device is detected by a voltage comparison circuit, and based on this potential difference, a microcomputer or the like is used. The control circuit detects the opening / grounding of the external device power output terminal. By detecting a subtle voltage change of the external device power output terminal, the control circuit detects the opening / grounding of the external device power output terminal. Can be detected.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a schematic configuration of a self-diagnosis device for an electronic device according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a schematic configuration of a self-diagnosis device of an electronic device in a conventional example.

[Description of Signs] 11 Control μCOM 12 Power supply output circuit for external device 13 Voltage comparison circuit 14 Power supply input 15 Power supply output terminal for external device

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Asabun Yamaguchi 4-3-1 Tsunashima Higashi, Kohoku-ku, Yokohama-shi, Kanagawa Prefecture Inside Matsushita Communication Industrial Co., Ltd. (72) Mikio Mori Innovator, Kohoku-ku, Yokohama-shi, Kanagawa Matsushita Tsushin Kogyo Co., Ltd. (72) Inventor Yukari Matsui 4-3-1 Tsunashima Higashi, Kohoku-ku, Yokohama, Kanagawa Prefecture F-term (reference) 2G014 AA02 AA04 AB01 AC18 5B048 AA00 CC11 DD10 EE01

Claims (2)

[Claims] A control circuit for controlling the electronic device; a power supply output circuit for an external device having a current limiting function; a comparison circuit for detecting a potential difference between input and output of the power supply output circuit for the external device; A self-diagnosis device for an electronic device, wherein the control circuit detects whether the external device power supply output circuit is open / ground. 2. The self-diagnosis device for an electronic device according to claim 1, wherein the control circuit is a microcomputer, and the potential difference detected by the comparison circuit is input to the A / D port.