JPS6134615A - Air conditioner - Google Patents

Abstract

PURPOSE:To make an execlusive oscillating circuit for a humidity sensor unnecessary, to reduce a production cost, and to make a printed board small in size by generating an AC voltage applied to the humidity sensor, by a software of a CPU. CONSTITUTION:A voltage waveform V30 is outputted from an output port 30 of a CPU 18. As for the waveform V30, its high frequency component is eliminated by a CR integration circuit 31, and it is formed to a waveform V31 which is between a square wave and a sine wave. This waveform V31 is applied to a terminal 52 of a humidity sensor 19, but since the potential of one terminal 53 is fixed to a reference voltage (2.5V) of an A/D converter 9, an AC voltage V52 of 2.5V amplitude is applied to the sensor 19 consequently. The voltage V52 is divided by humidity detecting element 32 and a temperature compensating thermistor 33, a divided potential V34 is fetched from a terminal 54, and it is inputted to a noninversion input terminal 44 of an operational amplifier 35. From the amplifier 35, an output signal voltage V56 is obtained in the form of a DC negative potential to the reference potential Vref. This voltage is inputted to a converter 9 and humidity is inputted as a digital signal to the CPU 18.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an air conditioner that receives information such as temperature and humidity through a CPUK, performs predetermined arithmetic processing, and is controlled by the output.

[Conventional technology]

A conventional air conditioner of this type will be explained based on FIG. 4. 1
is a commercial power source, and a power transformer 2 steps down the AC power voltage, and a power supply circuit 3 generates 5 V of DC, which is supplied to the entire control device. The input signal of the switch of the remote control 4 is converted into a digital signal d4 via the interface circuit 21.
Input to PU181C. Further, the temperatures detected by the temperature sensors 5 and 6 are respectively input to the analog input terminals of the A/D converter 9 as analog voltage signals '1#'! through temperature sensor input circuits 7.8. The humidity in the room detected by the humidity sensor 19 is output as an analog voltage signal a through the humidity sensor input circuit 20.
/D converter 9 is input to another input terminal. A/D
The converter 9 converts the analog signal alt"!e"l into a digital temperature value dlsd! , the digital humidity value d3 is input to the CPU 18 in a time-division manner. or more dI
The CPU 18 calculates the input signal +'t Ida *'4, and outputs the output signal d.

Determine. According to the output signal d of the CPU 18, -
The current is amplified through the relay driver 10 and the refrigeration compressor 1
ノ, fan motor 12. The solenoid valve 13 is connected to a relay 14,
At 15.16, φN- and φFF are set to control the temperature and humidity of the indoor air. Here, the humidity sensor 19 will be explained. A humidity sensor commonly used in air conditioners is a polymer humidity sensor, which utilizes the fact that the resistance value changes depending on the relative humidity of the surrounding air.

In other words, you are essentially passing a current rHn through the humidity sensor and reading its voltage drop VI (D. However,
In the case of a polymer humidity sensor, if a DC voltage is applied to flow the IHD, the characteristics will change due to dielectric polarization, so it is necessary to apply an AC voltage (usually about IKHz), flow the IHD, and read the AC voltage drop VHD. .

[Problem that the invention seeks to solve]

Therefore, in the conventional example, as shown in FIG. 4, an oscillation circuit 17 had to be provided in order to generate an alternating current voltage to be applied to the humidity sensor, although other circuits were unnecessary. Further, the provision of this oscillation circuit 17 has caused problems such as an increase in production costs and the need to reduce the size of the printed circuit board.

SUMMARY OF THE INVENTION An object of the present invention is to provide an air conditioner that solves the above-mentioned conventional problems and can reduce production costs and downsize the printed circuit board.

[Means for solving problems]

The air conditioner according to the present invention transmits information such as temperature and humidity to the CP.
In an air conditioner using a humidity sensor that requires application of an alternating current voltage as a humidity sensor that detects the humidity in an air conditioner that is input to U and subjected to predetermined arithmetic processing and controlled by the output, from the CPU. The present invention is characterized in that a voltage waveform is generated, and an alternating current voltage is applied to the humidity sensor from the same voltage waveform and a reference voltage.

[Effect]

According to the present invention, in a humidity detection circuit of a control device for an air conditioner, the above-mentioned conventional problems can be solved by generating an AC voltage to be applied to a humidity sensor using CPU software. .

〔Example〕

An embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, in which 1 is a commercial AC power supply, 2 is a power transformer, 3 is a power supply circuit, 4 is a remote control, 5.6 is a temperature sensor, and 7.8 is a Temperature sensor input circuit, 9 II A/D converter, 1
0 is a relay driver, 11 is a compressor, 12 is a fan motor, 13 is a solenoid valve, 14, 15.16 is a relay, 19
2 is a humidity sensor, and 20 is a humidity sensor input circuit.

The structural relationship of the above elements is the same as that of the conventional example shown in FIG. 4. However, in the present invention, there is no humidity sensor oscillation circuit, which was present as a component in the conventional example. Instead, as shown in Figure 2, CPUJ
The output port 30 of g is connected directly to the humidity sensor 19 or alternatively via a simple OR integration circuit 31. The OR integration circuit 31 and the humidity sensor input circuit 20 will be described below. The output port 30 of the CPU 1B is connected to an OR integration circuit 31, and the output of the OR integration circuit 31 is connected to the humidity detection element 32 of the humidity sensor 19. The humidity detection element 32 and the temperature compensation thermistor 330 voltage division point 34 are connected to a non-inverting input terminal 35 of the operational amplifier.

The DC 5V terminal 36 of the power supply circuit 3 shown in FIG. 1 includes a constant voltage diode 37 and resistors 38 and 39.

40, connected to the reference voltage terminal vref42 of the A/D controller 9 via a capacitor 41t', and at the same time connected to a resistor 43
The signal is inputted to the inverting input terminal 44 of the operational amplifier 47 via. An output terminal of the operational amplifier 47 is connected to an analog input terminal 49 of the A/D converter 9 via a rectifier diode 48 . A digital signal output terminal 50 of the A/D converter 9 is connected to an input port 51 of the CPU Ig.

Next, the operation of the above embodiment of the present invention will be explained.
The voltage waveform V shown in FIG. 3(4) from the output port 30 of the CPU 18. output. This waveform is CPUIItO
It is generated by software written inside. The voltage waveform VIIO outputted from the CPUJ 8 has high frequency components removed by the CRII division circuit 31, and is shaped into a waveform vs1 intermediate between a square wave and a sine wave as shown in FIG. 3). This waveform V□ is applied to the terminal 52 of the humidity sensor 19 (humidity detection element 32 and temperature compensation thermistor 33 are connected in series), and the potential of one terminal 53 is the reference voltage of the A/D converter. Voltage (2,5'
Therefore, as shown in FIG. 3C, an AC voltage V with an amplitude of 2.5V is applied to the humidity sensor 19. In other words, an AC voltage with an amplitude of ±2.5 V can be applied to the humidity sensor 19 using a 0-5 V square wave generated by software without providing a dedicated oscillation circuit.

The frequency of AC voltage vl11 can be easily and accurately determined by software! The AC voltage mit is divided by the humidity detection element 32 and the temperature compensation thermistor 33VC, and the divided potential "84" is taken out from the terminal 54 of the humidity sensor 19 and input to the non-inverting input terminal 44 of the operational amplifier 35. The input signal "III" is non-invertingly amplified, at the same time half-wave rectified by the rectifier diode 48, and smoothed by the electrolytic capacitor sHc, so that an output signal voltage v,6 is obtained in the form of a direct current negative potential with respect to the reference potential Vref. . This analog DC voltage is A
is input to the analog input terminal 49 of the /D converter 9,
The humidity is A/D converted and sent to the CPUJ as a digital signal.
8 is input.

〔Effect of the invention〕

As described above, according to the present invention, information such as temperature, humidity, etc.
In an air conditioner that is input to the PU, performs predetermined arithmetic processing, and is controlled by the output, the AC voltage to be applied to the humidity sensor is generated by the software of the CPU.
This eliminates the need for an oscillation circuit dedicated to conventional humidity sensors, and provides excellent effects such as reducing production costs and downsizing printed circuit boards.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, FIG. 2 is a diagram showing a specific example of the humidity sensor input circuit in FIG. 1, and FIGS. FIG. 4 is a waveform diagram for explaining the invention in detail, and FIG. 4 is a block diagram showing the configuration of a conventional example. 18...CPU, 19...Humidity sensor, 20...
Humidity sensor input circuit.

Claims (1)

[Claims] Information such as temperature and humidity is input to a CPU and subjected to predetermined arithmetic processing, and an air conditioner that is controlled by the output detects the humidity using a humidity sensor that requires the application of an alternating current voltage. An air conditioner characterized in that the CPU generates a voltage waveform, and the AC voltage is applied to the humidity sensor from the voltage waveform and a reference voltage.