JPS61162973A - Operation display circuit of washer - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a washing machine operation display circuit using a microcomputer, and particularly to a malfunction prevention circuit thereof.

2. Description of the Related Art Recently, microcomputers have begun to be used in household washing machines, and light emitting diodes (hereinafter simply referred to as LEDs) have been used as display elements. FIG. 4 shows an operation display circuit using this LED. In the figure, since the microcomputer 70, which performs pre-programmed predetermined operations, has limited input/output ports, scan outputs CO1, CO2, CO3 and synchronized L-'C1 input ports Bi1. Switch 73 based on the Bi2 signal
It is designed to detect whether ac or 74axa are on or off. For example, scan output C01 rises.

At this time, the transistor 71a is turned on, and the signal is applied to the collector side line of the Hi-multiple signal transistor 71a of vDD. If the switch 73a is in the on state, the microcomputer 70 detects the input signal and sets the microcomputer 70 to EO1Po)iLo, and the LED 77a lights up. The external appearance of this LED is as shown in FIG. 5, and the standard distance p between the terminals of the LED is 2.6 fi pinch, and the land distance of the printed circuit board is about 1 m+.

Problems to be Solved by the Invention However, if the conventional washing machine operation display circuit is used in a bathroom or when washing with hot water, water droplets may be generated due to the moisture resistance of the LED and the short land distance. It adheres and the insulation resistance decreases, causing the microcomputer 7o
had the problem of malfunctioning. That is, LED7
When the transistor 71a is turned on with insulation leakage occurring between the terminals of the transistor 7b, the LED 77a is sequentially biased, and a Hi-fold signal is applied to the collector terminal of the transistor 71b via the LEI)yTb, causing the scan signal to malfunction. .

In view of the above-mentioned problems, the present invention provides an operation display circuit in which a microcomputer does not malfunction even if dielectric breakdown occurs at the terminal portion of the LED or inside the LED.

Means for Solving the Problems The present invention integrates a microcomputer, an input circuit and a display circuit of the microcomputer, and separates the display LED circuit of the scan circuit and the switch-on circuit by a diode.

According to the above configuration, even if the LED circuit suffers dielectric breakdown, the current caused by the dielectric breakdown is blocked by the diode between the input circuit and the display circuit, and the input circuit will not malfunction.

Example Description will be given below based on the attached drawings.

As shown in Figure 2, the external appearance of a washing machine using a microcomputer is such that a top cover 2 is placed on the top of a body 1, and an operation display panel 3, a power switch 4, etc. are placed on the top cover 2. . As shown in FIG. 3, the operation display panel 3 is provided with a start/pause switch 30, a process changeover switch 31, a process progress display LED 32, a rinse changeover switch 33, a rinse process display LED 34, and the like.

The operation display circuit that performs such operation display includes a switch input circuit 75 and an LED display circuit 77, as shown in FIG.
, diodes 81a and 81b.

81c, the LED has a reverse breakdown voltage failure, or
Even if an insulation leak occurs, the structure prevents signals from being passed around to the switch input circuit 75. According to the above configuration, even if the LED 77b has a reverse breakdown voltage insulation leak, for example,
The Hi signal is transmitted from the collector terminal of the scan transistor 71a of the scan circuit 71 to the LED 77b where the insulation leak has occurred via the diode 81a and the LED 77ai, but due to the diode 81b, the switch input circuit 7
6 can be prevented from entering the surrounding signal.

Effects of the Invention As described above, the present invention provides a switch setting circuit and an LED
By separating the display circuit with a diode, LE
It is possible to prevent malfunction of the microcomputer by blocking reverse voltage failure of D or dew condensation from entering the switch input circuit, especially when it is used in a high humidity atmosphere such as a washing machine and is prone to dew condensation. In addition, the problem of malfunction can be solved.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram of an operation display circuit according to an embodiment of the present invention, Fig. 2 is an external view of a washing machine using a microcomputer, Fig. 3 is a front view of the same operation display panel, and Fig. 4 is a conventional one. The circuit diagram of the operation display circuit of 07o is an external view of the LED display element.
71...Scan circuit, 76...Switch input circuit, 77...LED display circuit. Name of agent Patent attorney Satoshi Nakao Male and 1 other Figure 1 70 --- Mike 1 Gon ζ -- Gua f -- Sukiyashi country; mo N 7S --- Stobna input 11! Horse mackerel 7γ--LED Izumimoto time V to δ'ft~8fc--Dive "-)" Fig. 3

Claims (1)

[Claims] a microcomputer that performs pre-programmed predetermined operations; a scan circuit connected to the microcomputer and that sequentially switches signals; a switch input circuit connected to the scan circuit that applies input signals to the microcomputer; and the scan circuit. An operation display circuit for a washing machine, comprising an LED display circuit connected in series to a switch input circuit and a switch input circuit, and connected to the microcomputer to perform a predetermined display, and a diode connected between the switch input circuit and the display circuit.