JPH02257998A - Sensor output amplifying circuit for clothes dryer - Google Patents

Abstract

PURPOSE:To perform dry operation at a high temperature, to not alone shorten a time required for operation but also bring a sensor output into a linear state, to reduce the generation of noise and ripple, and to enable accurate control of humidity of clothes after drying by a method wherein an absolute humidity sensor is used, and based on a signal from an amplifying circuit to amplify an output from the sensor and cut a noise in an iso-phase, a load, e.g. an electric heater, is controlled. CONSTITUTION:A measuring circuit 23 amplifying a value detected by a humidity sensor 8 by means of a bridge circuit 21 and an amplifying circuit 22 to input it as Vs measures a maximum value Vm in a given time and outputs it to a microcomputer 20 to store it. A value Vm- obtained by subtracting 8 value preset according to each operation mode from the maximum value Vm measured by the measuring circuit 23 is compared with a value Vs detected by the humidity sensor 8, and a detecting circuit 24 to detect a time when Vs is Vm- also outputs a signal to the microcomputer 20. A temperature control circuit 25 to input a value detected by a temperature sensor 7 and compare it with a preset temperature (50 deg.C or 75 deg.C) outputs a signal to the microcomputer 20.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to a sensor output amplification circuit for a clothes dryer that can accurately control the humidity of clothes after drying.

(b) Conventional technology Conventionally, these nine types of clothes dryers are
As disclosed in Publication No. 8 etc., inside the casing,
A rotating drum for storing clothes, a motor for driving this drum, an electric heater for heating the clothes, a temperature sensor for detecting the heating temperature, a relative humidity sensor for detecting the relative humidity of the clothes, and a sensor for detecting the relative humidity of the clothes. The dryer is equipped with a control device that controls the operation of the clothes dryer based on the output, and is configured to dry the clothes by placing damp clothes in a rotating drum kept at a high temperature and rotating the drum. The relative humidity sensor is made of a polymer ↑B fat compound.
It is installed near the rotating drum to monitor the relative humidity inside the rotating drum during drying operation, and to monitor the relative humidity Rh.
It is configured to turn off the electric heater and stop the drying operation when the temperature drops to a certain value. For example, the absolute value of the relative humidity sensor detects the target Rh of 30% in normal dry mode, and 50% in ironing mode (to keep it slightly damp in consideration of ironing after drying). to control the humidity of clothing. Here, the relative humidity Rh is expressed in % by the following formula.

Rh- (absolute humidity at that time) 7' (maximum value of absolute humidity)
Note that absolute humidity refers to the amount of moisture contained in 1 m3 of air at a certain temperature, and is expressed in g/m'.

(c) Problems to be Solved by the Invention However, the above configuration has the following problems, and improvements have been desired.

■Since the drying operation is controlled based on relative humidity, the relative humidity value changes depending on the amount of clothing, material, dampness, etc., and all of these changes are based on the same standard (for example, mode, the humidity of the clothes after drying cannot be accurately controlled. For example, if there is a small amount of clothes, the relative humidity value is low, so becomes insufficient.

(2) Since the relative humidity sensor is made of a polymer skin oil compound, it has poor high-temperature durability due to its characteristics, and is particularly susceptible to deterioration when the temperature inside the rotating drum exceeds 70°C. Therefore,
Drying operation cannot be performed at high temperatures (for example, 75°C), and it takes a long time to complete the operation.

■In addition, relative humidity sensors have hysteresis due to their characteristics, resulting in large errors and slow response.
Lack of stability when foreign matter adheres.

■Furthermore, when an AC voltage is applied to the relative humidity sensor,
It is easy to handle because the range of change in AC resistance value is large, but on the other hand,
Since the change is exponential, it is difficult to linearize the sensor output with respect to relative humidity, making it difficult to accurately control humidity.

The present invention has been developed in view of these points, and by using an absolute humidity sensor, it not only enables drying operation under high temperatures and shortens the time required for operation, but also linearizes the sensor output. At the same time, it reduces noise and pull,
To provide a sensor output amplification circuit for a clothes dryer that can accurately control the humidity of clothes after drying, has good performance, and has a large energy-saving effect.

(d) Means for Solving the Problems The present invention provides a rotating drum for storing clothes in a cage, a motor for driving the drum, an electric heater for heating the clothes, and a temperature detecting device inside the cage. Equipped with a temperature sensor, an absolute humidity sensor that detects the absolute humidity inside, and a control device that controls the operation of the clothes dryer based on the outputs of these sensors, it heats the inside of the rotating drum containing damp clothes to a high temperature. The device dries clothes by forcibly circulating the air inside the drum to remove moisture from the high-humidity air, and the control device amplifies the output from the absolute humidity sensor. an amplifier circuit that cuts in-phase noise, a low-pass filter that inputs the signal from this amplifier circuit and cuts anti-phase noise, and inputs the signal from this low-pass filter and the reference scan voltage signal. A comparator for comparison, and a load on the electric heater etc. is controlled based on the signal from this comparator.
1. A sensor output amplification circuit for a clothes dryer, characterized in that the circuit comprises a microcomputer that controls the load based on a signal from the comparator.

(E) Function The humidity control device for a clothes dryer according to the present invention has the following functions due to the above structure.

■Using an absolute humidity sensor, it is possible to perform humidity control according to the absolute humidity that changes depending on the temperature, and the drying operation can be ended when the absolute humidity drops by a predetermined value.
Even if the amount of clothes, material, moisture level, etc. change, the clothes can be completely dried without causing excessive drying or insufficient drying, and the desired humidity level of the clothes after drying can be achieved. can be finished with high precision.

■Uses an absolute humidity sensor, so clothing can be heated to high temperatures (
For example, it can be dried at a temperature of 75° C.), which not only shortens the time until the end of operation, but also enhances the sterilization effect.

■Also, due to its characteristics, absolute humidity sensors have no hysteresis, have a quick response, and have stable characteristics even when foreign matter adheres to them, making it possible to perform high-precision and quick humidity control.

■In addition, by using an absolute humidity sensor, the sensor output can be taken out in a linear form, and in-phase and anti-phase noise can be cut using an amplifier circuit and a low-pass filter, making it possible to use a simple circuit. The configuration allows for highly accurate humidity control.

(f) Example Embodiments of the present invention will be described below with reference to the drawings.

Figure 1 shows the overall configuration of a clothes dryer. This dryer is
Inside the casing 1, there is a rotating drum 2 in which clothes are placed, a motor 4 that drives this drum with a belt 3, two large and small electric heaters 5 and 6 that heat the clothes, and a temperature sensor that detects the internal temperature. 7, an absolute humidity sensor 8 that detects the internal absolute humidity, and a control device 9 that controls the operation of the clothes dryer based on the outputs of these sensors. 10 is an air intake provided on the back side of the casing 1, and 11 is an air intake provided near this intake.
12 is a condenser that takes in and condenses the highly humid air in the rotary drum 2 through an air collecting pipe 13; This is a discharge pipe that discharges the air from which the air has been removed to the outside of the machine, and these constitute four air circuits. 15 is a lower tank that collects and stores the water liquefied in the condenser 12, and 6 is a pump that pumps the water accumulated in the lower tank 15 to the upper tank 18 via piping 17, and these constitute a water circulation circuit. There is.

This clothes dryer maintains the interior of the rotating drum 2 at a high temperature using electric heaters 5 and 6, and rotates the drum with clothes placed therein, and also forcibly circulates the air inside the drum to maintain high humidity. It dries clothes by removing moisture from the air.

Here, both the temperature sensor 7 and the absolute humidity sensor 8 are installed in the air collection pipe 13. Further, the water accumulated in the water circulation circuit is discarded from the upper tank 18 for convenience of the user.

FIG. 2 shows the electrical circuit of the control device 9, including the power switch,
Based on the operation section 19 which has an operation mode, a changeover switch, a Δ value setting switch for each operation mode as described later, a display circuit, etc., and signals from this operation section as well as signals from the temperature sensor 7 and humidity sensor 8. A microcomputer that controls the temperature and humidity of a clothes dryer.
20 and the value detected by the humidity sensor 8 is amplified by a bridge circuit 21 and an amplifier circuit 22 and inputted as Vs, and the maximum value Vm in a predetermined time is measured and outputted to the microcomputer 20 and stored. A measuring circuit 23 that calculates the value Vm - Δ obtained by subtracting a preset value Δ according to each operation mode from the maximum value Vm measured by the measuring circuit 23 and a value Vs detected and detected by the humidity sensor 8. A detection circuit 24 detects when Vs becomes Vm-Δ and sends a signal to the microcomputer 20.
and a temperature control circuit 25 which inputs the value detected by the temperature sensor 7, compares it with a preset temperature (50°C or 75°C), and sends a signal to the microcomputer 20.
It is composed of.

Here, FIG. 3 shows changes in the output Vs of the absolute humidity sensor 8 during drying operation, which will be described later. Vs is the maximum value V for a predetermined time
The drying operation is stopped when the temperature drops by Δ from m.

The microcomputer 20 controls and controls a temperature control circuit to turn off the electric heater 5.6 and stop the drying operation when Vs becomes Vm-Δ based on the signals from the measuring circuit 23 and the detection circuit 24 described above. Based on the signal 25, the electric heaters 5 and 6 are energized to maintain the inside of the rotary drum 2 at a set temperature, and the loads of the motor 4 that drives the rotary drum 2, the pump 16 of the water circulation circuit, etc. are controlled.

Here, the operating functions of the clothes dryer will be explained based on FIG. 4. Two types of operation modes are preset in the control device 9. Specifically, there is a high temperature mode for controlling the temperature inside the rotating drum 2 at 75°C by energizing both electric heaters 5 and 6 (2Kw + IKw) for clothes made of cotton, etc., and a chemical IR mode.
This is a low-temperature mode in which only the electric heater 6 (2Kw) is energized and the temperature inside the rotating drum 2 is controlled at 50° C. for clothes made of textiles. In addition, in each of these operation modes, there are three drying modes: dry mode, normal mode, and ironing mode, and as described above, the Δ value corresponding to each mode is preset in the control device 9. There is.

The user then selects the operating mode and drying mode to dry the clothes as desired.

Further, the operation of the clothes dryer is roughly divided into drying operation and cooling operation, as shown in FIG. That is, when operating in high temperature mode, the electric heaters 5, 6, motor 4,
and a drying operation in which all the pumps 16 are turned on, and a cooling operation in which only the electric heaters 5 and 6 are turned on and only the FFL motor 4 and the pump 16 are turned on.

Specifically, as shown in the flowchart of FIG. 6, after turning on the operation switch and setting each mode (temperature setting) and setting the Δ value, drying operation begins.

In the drying operation, control of each load (air heaters 5, 6, motor 4, pump 16, etc.), calculation and output of the maximum value Vm measurement Vm-Δ, and comparison control of the detected value Vs and Vm-Δ are performed. The drying operation is stopped when Vs≦Vm−Δ,
Start cooling operation. When the cooling operation starts, the electric heaters 5 and 6 stop all loads when the detected value of the 0FFL temperature sensor 7 reaches 35° C., and the entire operation ends.

Here, the bridge circuit 21 includes, as shown in FIG. 7, an absolute humidity sensor 8 consisting of a series circuit of a sealed thermistor 8a and a partially ventilated thermistor 8b, and an absolute humidity sensor 8 which is bridge-connected to this series circuit. By applying a DC voltage of 15 V to the series circuit, a sensor output of 0 to 12 mV is obtained.

Further, as shown in FIG. 8, the amplifier circuit 22 applies the 10 and - outputs from the bridge circuit 21 to each of the 10 power sources, and also applies a reference voltage to the 1 power source via feedback resistors 29 and 30. Two operational amplifiers 27, 28 are connected in series with each other. This amplifier circuit 22 cancels out the in-phase noise contained in the output of the bridge circuit 21 using two operational amplifiers 27 and 28, and also reduces only the potential difference between the + and - outputs from the bridge circuit 21 by 200 times ( 1,6-4.It is amplified to OVI.

This is a 31fiCR type low-pass filter, which cuts out the negative phase noise contained in the output of the amplifier circuit 22, and then outputs a signal to the comparator (2).

Furthermore, 32 is a CR type D/A converter, which is 1.5~
A reference scan voltage signal of 4.1V is generated and output to the comparator (1).

Comparator (2) compares the signal from the snake-pass filter 31 and the signal from the D/A converter 32 to detect the maximum value Vm of the absolute humidity sensor 8.

That is, the output of the bridge circuit 21 includes induced ripples from the surrounding AC lines (short fluctuations in the waveform period (a) in Figure 8), external noise ((a) in Figure 8). spike waveform), and the power supply DC15 of the bridge circuit 21
This is a variation in V ((a) in FIG. 8) a variation with a long period of the waveform. Of these fluctuations, the induced ripple and external noise have in-phase waveforms, and as mentioned above, the two operational amplifiers 2 and
Cut by 7.28. And the amplifier circuit 22
The output waveform of
Only the fluctuations due to However, this DC15V
As shown in FIG. 8(c), the variation in is considerably reduced by the low-pass filter 31, so that it does not have an adverse effect such as chattering on the operation of the comparator (2).

Then, from the maximum value V m obtained by the measurement circuit 23, a value △ determined for each mode (operation mode, dry mode) is determined.
The voltage value Vm-Δ obtained by subtracting Vm-Δ is applied to the human power of the comparator (2), and compared with the sensor output VS applied to the -human power.

Then, when the sensor output VS decreases to Vm-Δ, the output of the comparator (2) changes from 0 to 1, and the microcomputer 20 stops the drying operation. Incidentally, as shown in Figure 4, the value of Δ is 3.5 mV in the dry mode and normal mode, and 1 mV in the iron mode in the high temperature mode.
V, in the case of low temperature mode, it is 2.5 mV in dry mode and normal mode, and 0.75 mV in iron mode.

With the above configuration, the clothes dryer of the present invention can use the absolute humidity sensor 8 to perform humidity control according to the absolute humidity that changes depending on the temperature, and starts drying when the absolute humidity decreases by a predetermined value Δ. The amount of clothing you can finish,
Clothes can be completely dried without excessive drying or insufficient drying even if the material, moisture level, etc. change, and it is also possible to precisely finish the clothes to the desired humidity level after drying. can.

Furthermore, since the absolute humidity sensor 8 is used, clothes can be dried at high temperatures (for example, 75° C.), which not only shortens the time until the end of operation, but also enhances the sterilization effect.

Furthermore, the absolute humidity sensor 8 has no hysteresis due to its characteristics, has a quick response, and has stable characteristics even when foreign matter is attached, so that high-precision and rapid humidity control can be performed.

In addition, by using the absolute humidity sensor 8, the sensor output can be taken out in a linear form, and in-phase and anti-phase noise can be cut by the amplifier circuit 22 and low-pass filter 31. It is possible to perform high humidity control.

(G) Effects of the Invention As described above, according to the present invention, by using an absolute humidity sensor, it is possible to perform drying operation under high temperatures, and not only shorten the operation time but also make the sensor output linear. 1. It is possible to provide a sensor output amplification circuit for a clothes dryer which has good performance and a large energy-saving effect by reducing noise and pull and accurately controlling the humidity of clothes after drying.

[Brief explanation of drawings]

Fig. 1 is a perspective view of a clothes dryer showing an embodiment of the present invention, Fig. 2 is an electric circuit diagram showing a humidity control device for the clothes dryer, and Fig. 3 is a time chart showing changes in the output of the absolute humidity sensor. , Fig. 4 is a chart showing the mode switching function of the clothes dryer, Fig. 5 is a chart showing the operating status of each load, Fig. 6 is a flowchart showing the operation control of the clothes dryer, and Fig. 7 is a chart showing the operation control of the clothes dryer. FIG. 8 is an electrical circuit diagram of the bridge circuit, and FIG. 8 is an electrical circuit diagram of the sensor output amplification circuit. ]...Casing, 2...Rotating drum, 4...Motor 5.6...Electric heater, 7...Temperature sensor
8...Absolute humidity sensor, 9...Control device, 20.
...Microcombeater 21...Bridge circuit,
22...Amplification circuit, 23...Measurement circuit, 31...
low pass filter.

Claims (1)

[Claims] (1) Inside the casing, there is a rotating drum for storing clothes, a motor for driving this drum, an electric heater for heating the clothes, a temperature sensor for detecting the internal temperature, and an absolute humidity for detecting the internal absolute humidity. The clothes dryer is equipped with sensors and a control device that controls the operation of the clothes dryer based on the outputs of these sensors. The device dries clothes by removing moisture from highly humid air by circulating the air through the air, the control device comprising:
An amplifier circuit that amplifies the output from the absolute humidity sensor and cuts out in-phase noise, a low-pass filter that inputs the signal from this amplifier circuit and cuts out anti-phase noise, and a signal from this low-pass filter that serves as a reference. It consists of a comparator that inputs and compares the scan voltage signal, and a microcomputer that controls the load such as the electric heater based on the signal from the comparator. A sensor output amplification circuit for a clothes dryer, characterized in that the load is controlled by