JPH05323036A - Water detection circuit - Google Patents

Abstract

(57) [Summary] [Purpose] To detect the presence or absence of water while applying an AC voltage between electrodes provided in the water detection range to prevent electrolysis. [Configuration] Two outputs of a microcomputer are alternately inverted in a time division manner, and water is detected at a timing when a transistor can be turned on through water to which an AC voltage is applied. [Effect] The water detection circuit can be configured at a low cost without suppressing the occurrence of electrolysis and lowering the detection performance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a residual water detection circuit for spilled water on the inside of a can or floor.

[0002]

2. Description of the Related Art Conventional water detection circuits have been used to detect residual water inside a can or to detect spilled water on the floor.

As a conventional example, the one shown in FIG. 3 is a circuit diagram of a water detection circuit for detecting the residual water in the can body, and 1a and 1b are electrodes attached to the can body A for detecting the residual water. Two
Is a DC power source, 3 and 4 are transistors, and 5 is a microcomputer (hereinafter referred to as a microcomputer) that controls the equipment and inputs a signal from the transistor 4 to determine the presence or absence of residual water. 6, 7, 8, 9, and 10 are resistances, respectively.

When there is no residual water in the can A, 1
Since a and 1b are open and the base current does not flow, the transistor 3 is in the off state, as a result, the transistor 4 is also off, and the input of the microcomputer 5 becomes Hi.
The microcomputer 5 judges that there is no residual water, and controls the equipment based on the judgment that there is no residual water.

When there is residual water in the can body A to the extent that both of the electrodes are submerged, a base current flows through the route of the resistor 7, the electrode 1a, water and 1b, the transistor 3 is turned on, and the transistor 4 is turned on. Is turned on, the input of the microcomputer 5 becomes Low, and the microcomputer 5 determines that there is residual water and controls the equipment based on the determination that there is residual water.

[0006]

In the above-mentioned conventional method, although there is no problem in detecting the presence or absence of water, in order to apply a DC voltage to the inside of the can and water such as spilled water, electrolysis of water is performed. There is a problem that hydrogen may be induced to generate hydrogen, and electrolytic corrosion may occur due to electrolysis to attach dust to the electrodes, which necessitates replacement after a certain period of time.

In order to prevent this electrolysis, a method of applying an alternating current to the electrodes is conceivable, but it is usually conceivable to use a transformer, which has the drawback of increasing the cost.

An object of the present invention is to solve the problems of the above-mentioned prior art and to provide a more accurate and inexpensive water detection circuit.

[0009]

To achieve this object, the present invention provides a microcomputer for controlling equipment, two electrodes arranged at a distance from each other, and one of the electrodes via a resistor. The base of the transistor is connected, the other end of the electrode is connected to the first output port of the microcomputer, the diode whose anode is connected to the emitter of the transistor is connected in parallel to the base-emitter resistor, and the constant voltage is applied. A collector connected from a power source through a resistor is connected to an input port of the microcomputer, an emitter of the transistor is connected to a second output port of the microcomputer, an output of a first output port of the microcomputer, and a second output port of the microcomputer. Is a circuit for alternately inverting the logic of the output of the output port and applying an alternating current between the electrodes.

[0010]

According to the present invention, since the outputs of the two microcomputers are alternately inverted and an alternating current is caused to flow between the electrodes, the present invention suppresses the occurrence of electrolysis without separately providing an AC power source for water detection. The presence or absence of water can be detected.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the water detecting circuit of the present invention will be described below with reference to FIG. FIG. 1 shows a water detection circuit according to an embodiment of the present invention. In order to simplify the description, a case where residual water in a can is applied to the detection circuit will be described. The same parts as those in the conventional example are designated by the same reference numerals and the description thereof will be omitted. Reference numeral 11 is a transistor, 5 is a microcomputer for controlling the equipment, and the signal of the transistor 11 is input to determine the presence or absence of residual water. 12 is a diode, and the base and emitter of the transistor 11 are reversed at the time of the first output Hi. Biased only for VF, 1
3, 14 and 15 are resistors.

Next, the operation will be described. Microcomputer 5
Keeps inverting the logic of the first output and the logic of the second output alternately in a time division manner. Therefore, the voltage applied to the electrodes 1a and 1b is an alternating current as shown in FIG. If there is no water in the can body, the electrodes 11 are open, the transistor 11 is turned off, the microcomputer input becomes Hi, and it is determined that there is no water in the can body A.

Next, the operation when residual water is generated in the can A will be described. In the first phase (odd phase) in FIG. 2, the first output is Hi and the second output is Low. In this case, the diode 12, the resistor 13,
A current flows through the second output path outputting Low through the electrodes 1a, water, and 1b. In this case, since the transistor 11 cannot be turned on, the microcomputer side ignores the input result or does not perform the input process in this phase. The input processing is performed when the processing shifts to phase 2 (even phase) in order to switch the output in time division. In the second phase (even phase), the electrode 1b,
Since the current flows through the first output path that outputs water, 1a, the resistor 13, the transistor 11, and the Low, the transistor 11 is turned on, the microcomputer input becomes Low, and the microcomputer 5 is controlled based on the determination that there is residual water. Will be done. In this method, since Hi and Low are switched in a time division manner, detection cannot be performed at the timing (odd phase). However, switching the detection timing in accordance with the output timing can be easily realized by using a microcomputer.

[0014]

As is apparent from the above embodiments, according to the present invention, since an alternating current is applied to the electrode for detecting the presence of water, there is no occurrence of electrolysis of water, and the microcomputer is used. Since the two outputs are alternately inverted and switched, there is no need to provide a separate transformer to supply an AC voltage.
The circuit can be constructed at low cost without degrading the detection performance.

[Brief description of drawings]

FIG. 1 is a water detection circuit diagram of an embodiment of the present invention.

FIG. 2 is a timing chart of the voltage between the output port and the electrode of the same embodiment.

[Figure 3] Conventional water detection circuit diagram

[Explanation of symbols]

 1a, 1b Electrode 5 Microcomputer 11 Transistor 12 Diode 13, 14, 15 Resistance

Front page continued (72) Inventor Shinji Miyauchi 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (1)

[Claims] 1. A microcomputer for controlling equipment, two electrodes arranged at a distance from each other, and one of the electrodes connected to a base of a transistor through a resistor,
The other end of the electrode was connected to the first output port of the microcomputer, the diode whose anode was connected to the emitter of the transistor was connected in parallel to the base-emitter resistor, and was connected from the constant voltage power source through the resistor. The collector is connected to the input port of the microcomputer, the emitter of the transistor is connected to the second output port of the microcomputer, the output of the first output port of the microcomputer and the output of the second output port of the microcomputer. A water detection circuit that alternately inverts the logic of to apply an alternating current between the electrodes.