JPH02243190A - Turbidity detector - Google Patents

Abstract

PURPOSE:To eliminate the influence of filth and foam on an attachment part of a photo-sensor by providing a turbidity detector that consists of a light emitting output control circuit for a light emitting element of the photo-sensor, a switching circuit of the photo-sensor, and a peak value detecting device which detects the peak output voltage of a light receiving element. CONSTITUTION:A light emitting output control circuit 25 impresses signals from a microcomputer 20' on an emitter terminal of a transistor 26 through D/A conversion circuit 25 to constitute a luminous output control circuit 26'. A light emitting element 23A of a photo-sensor 23 and a switching circuit 28 are connected to a collector terminal of the transistor 26. Resistor 32a and 32b are connected to an output terminal of a light receiving element 23B of the photo-sensor 23, and those resistance values are applied on a peak detecting circuit 35 through an output terminal of the light receiving element 23B by turning a transistor 33 on and off by the microcomputer. The peak detecting circuit 35 is an emitter follower circuit of a transistor 36, and a resistor 37 and a capacitor 38 are connected to an emitter terminal to impress signals on a voltage detecting terminal of the microcomputer 20'.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a turbidity detection device for a washing machine or the like that detects the turbidity of a liquid in a washing tub to control washing or rinsing.

2. Description of the Related Art One example of a washing machine that controls washing or rinsing by detecting the turbidity of a liquid in a washing tub is disclosed in Japanese Patent Application Laid-Open No. 61-50596. In other words, it optically detects the turbidity of water in the washing tub.

Equipped with a light sensor consisting of a light emitting element and a light receiving element.

The degree of contamination or the degree of rinsing was detected based on changes in the output signal of the light receiving element of this optical sensor.

Problems to be Solved by the Invention However, the control method disclosed in Japanese Unexamined Patent Publication No. 61-50596 has the following problems.

(1) When the mounting part of the optical sensor becomes dirty, the output voltage of the optical sensor decreases and the dirt cannot be detected, so a means for removing dirt from the light transmitting part is required.

(2) If only the optical sensor output voltage is detected, the turbidity will decrease due to the influence of bubbles, making it impossible to distinguish between dirt and bubbles.

In view of the above problems, it is an object of the present invention to eliminate the influence of dirt on the optical sensor mounting portion and also eliminate the influence of bubbles.

Means for Solving the Problems In order to achieve the above objects, the present invention includes a light emission output control circuit that controls the light emission level of a light emitting element of an optical sensor, a switching circuit that turns on the light emitting element for a certain period of time, and a peak output control circuit of the light receiving element. It is equipped with a peak value detection circuit that detects voltage.

Effect of the Invention According to the present invention, since the light emitting time of the light emitting element of the optical sensor can be shortened, the light emitting output of the light emitting element can be greatly increased, and even if the optical sensor mounting part is dirty, sufficient light can be transmitted. It becomes possible to obtain a post-luminescence condition. In addition, since it is equipped with a peak value detection circuit, it is possible to take the peak value of the optical sensor signal input in synchronization with one light emission, and obtain data that removes the drop in turbidity due to bubbles, as well as remove noise. It becomes possible.

Example The present invention will be described in detail below with reference to one drawing.

First, FIG. 2 shows an embodiment of a washing machine control device having a turbidity detection device according to the present invention. In Figure 2, 1
is an AC power supply, which supplies power to the control device 2, washing motor 3, its phase advance capacitor, 4% water supply valve 6, and drain valve 6. The control device 2 is.

A signal processing circuit 20 consisting of a microcomputer; an operation display circuit 21 consisting of a display device or a key switch;
It consists of a power control circuit 221 that controls the washing motor 3 or the water supply valve 6 and the drain valve 6, an optical sensor 23 consisting of a light emitting element and a light receiving element, and a sensor section 24 such as a water level sensor that detects the water level in the washing tub.

Next, first, an embodiment of the turbidity detection device according to the present invention will be described. In the figure, 20' is a microcomputer 2d having a MU/D conversion circuit and a pulse width control circuit, which are the core of the signal processing circuit 20 in FIG.

A signal (hereinafter referred to as PWM signal) whose pulse width is controlled by the microcomputer 20' is sent to the D/A conversion circuit 25.
In addition to converting to DC voltage. The output signal of the D/MU conversion circuit 26 is applied to the base terminal of the transistor 26. An emitter resistor 27 is connected to the emitter terminal of this transistor 26.
is connected, it is possible to configure a light emission output control circuit 26' that can control the current based on the base voltage. The light emitting element 23 of the optical sensor 23 is connected to the collector terminal of the transistor 26.
The person and the switching circuit 28 are connected in series.

The switching circuit 28 is controlled on and off by the microcomputer 20' via resistors 29 and 31. The output terminal of the light receiving element 23B of the optical sensor 23 has a resistor 32&
and resistor 32b are connected in parallel, and this resistor 3
The load resistance values of 21L and 32b can be varied by turning on and off the transistor 33 using a microcomputer.

The light is applied to the peak value detection circuit 36 from the output terminal of the light receiving element 23B. The peak value detection circuit 36 is a transistor 36
The emitter follower circuit has a resistor of 37 at the emitter terminal.
and a capacitor 38 are connected in parallel to apply a signal to the voltage detection terminal (MU/D terminal) of the microcomputer 20'.

FIG. 3 shows a structure in which an optical sensor 23 is attached to a drain cock 8 at the bottom of a washing tub 7 of a washing machine. The inside of the drain cock 8 through which the washing liquid flows is less affected by foam from washing agitation;
Dirt tends to adhere and transmittance decreases. Even if the transmittance decreases, the present invention can increase the output and gain of the optical sensor 23, and no dirt removal device is particularly required.

FIG. 4 is a timing chart showing the operation of the present invention, in which the current IF of the light emitting element 23A is pulse-driven, the current application time Ton is reduced, and the pulse width duty with respect to the on-off period To is set to 1/6 or less. , 178~1/
10. The Ton time is 60 to 100 m56C and the period is 0.5 to 1 second. We is the optical sensor output voltage and fluctuates due to the influence of bubbles and noise. In other words, if there are many bubbles, the output voltage will decrease, and if the peak voltage is detected,
The effect of bubbles can be removed. vO is the output voltage of the peak value detection circuit 35, which holds the output voltage unaffected by bubbles, performs Nim/D conversion before the switching circuit 28 turns off,
The pulse drive of the light emitting element, which imports data into the microcomputer, and the timing of the MU/D conversion input make it possible to increase the light output level per light, and even if the drain cock is dirty, it will not emit light. The light passes through and reaches the light-receiving element, allowing the detection of dirt in the washing liquid or degree of rinsing. Additionally, if the drain cock is extremely dirty, the output resistance of the optical sensor 23 is increased.

Make changes detectable. That is, the transistor 33 in FIG. 2 is normally on, but if the drain cock is heavily contaminated and the optical sensor output signal Va becomes smaller than the set value, the transistor 33 turns off.
Increase the load resistance of the optical sensor 23.

FIG. 5 shows an optical sensor signal when the turbidity detection device according to the present invention is installed in a fully automatic washing machine, and shows that voltage fluctuation becomes extremely large during washing due to the influence of foam. As the number of bubbles increases, the turbidity decreases, so the optical sensor output voltage is large when there is no effect of bubbles, and the peak of the voltage is detected to eliminate the effect of bubbles.

FIG. 6 shows the characteristics of the optical sensor output voltage. When there is little turbidity, the peak light emitting element current IF is small, and when the drain cock is dirty, the turbidity is large and the peak light emitting element current IFB is increased. The peak value of the light-emitting element current is determined by the rinsing water supply or.

Before washing, the Mu/D conversion input voltage VO is controlled to be at the center of the Mu/D conversion dynamic range or a set voltage higher than the center.

As another embodiment of the peak value detection circuit, the same effect can be obtained even if the maximum value is detected by an internal program of a microcomputer.

Furthermore, it goes without saying that the present invention is applicable not only to washing machines but also to dishwashers and rice washers.

Effects of the Invention As described above, the present invention pulse-drives the light-emitting element of the optical sensor with a small duty and detects the output signal of the light-receiving element in synchronization with the timing of the pulse drive. The output can be increased. Therefore, there is no need for a dirt removal device on the optical sensor mounting part.
An inexpensive turbidity detection device can be realized. In addition, the pulse drive reduces the loss of light emitting and light receiving elements, and the influence of temperature due to self-heating is also reduced. In addition, by connecting a peak value detection circuit with a large discharge time constant to the optical sensor output side, the optical sensor output decrease signal due to the influence of foam is removed, and only the signal when there is little foam is detected. Only signal degradation due to dirt can be detected. If we integrate the photosensor output signal.

It is not possible to distinguish between a decrease in turbidity due to the influence of bubbles and a change in turbidity due to dirt.

In addition, by switching the load resistance on the optical sensor output side, the sensor output voltage can be increased when the optical sensor's light emitting current cannot be increased, and even if the optical sensor mounting part becomes even more dirty, it can be handled by simply switching the resistance. can. If the drain cock is dirty, the optical sensor load resistance can be reduced to increase decomposition.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram of a turbidity detection device according to an embodiment of the present invention, Fig. 2 is a block diagram of a control device for a washing machine equipped with the turbidity detection device, and Fig. 3 is a circuit diagram of a turbidity detection device according to an embodiment of the present invention. Fig. 4 is a timing chart of the turbidity detection device, Fig. 6 is a graph showing changes in the optical sensor output signal during operation of the fully automatic washing machine, and Fig. 6 is a graph showing changes in the optical sensor output signal during operation of the fully automatic washing machine. It is a characteristic diagram of a turbidity detection device. 23 people...Light emitting element, 23B...Light receiving element, 23...Light sensor, 26'...
Light emission output control circuit, 28... switching circuit,
35...Peak value detection circuit. Name of agent: Patent attorney Shigetaka Awano and 1 other person 2nd figure, 2nd figure, 2nd figure, 2nd figure, 2nd figure, 2nd figure, 2nd figure, 2nd figure, 2nd figure, 2nd figure, 2nd figure, 2nd figure: Time wave (17th figure, 9th figure)

Claims (1)

[Claims] an optical sensor consisting of a light emitting element and a light receiving element; a light emitting output control circuit that controls the light emitting output of the light emitting element; a switching circuit that turns on the light emitting element for a certain period of time; and a peak value that detects a peak output voltage of the light receiving element. Turbidity detection device consisting of a detection circuit.