JPH0531098B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a sensor that optically detects the occurrence of dew condensation, and particularly to a dew condensation sensor suitable for an air conditioner in a vehicle such as an automobile.

[Conventional technology]

In air conditioners for vehicles such as automobiles,
For example, as described in Japanese Unexamined Patent Publication No. 57-55211, a dehumidifying function is provided to prevent condensation on the window glass surface, especially the front window glass surface, and this dehumidification function is automatically activated when there is a risk of condensation occurring. There are some that are designed to activate the function.

By the way, various types of dew condensation sensors necessary for such air conditioners have been proposed in the past, and one type is a so-called optical dew condensation sensor.

Conventional dew condensation sensors, such as those disclosed in Utility Model Application Publication No. 59-9, have a light emitter and a light receiver installed adjacent to each other in the vehicle interior, and are placed in close contact with the window glass. Condensation was detected by reducing the amount of light reflected by the reflector.

[Problem that the invention seeks to solve]

The above-mentioned conventional technology does not take into account the fact that light is scattered and the reflected light is reduced due to dirt on the reflector, and false positives may occur due to dirt generated due to long-term use. There was a problem that it was easy to cause

An object of the present invention is to provide a non-contact type dew condensation detection means that can eliminate the influence of dirt on the dew condensation surface, determine the amount of light attenuation due to dew condensation alone, and can be used with high reliability over a long period of time. be.

[Means for solving problems]

According to the present invention, the above problem is solved by detecting dew condensation using first and second wavelength bands of light having different transmittances to water, and by detecting dew condensation as a dew condensation generation surface. This problem can be solved by using the surface of a metal member embedded in the glass plate.

[Effect]

These first and second lights are affected differently only by the presence of water, and are affected the same by dirt other than water, so excluding detection errors due to dirt, etc., In other words, only the presence of dew condensation can be detected, and the occurrence of dew condensation can be detected more quickly and reliably due to the good heat conduction properties of the metal member.

〔Example〕

Hereinafter, the dew condensation sensor according to the present invention will be explained in detail with reference to illustrated embodiments.

FIG. 1 shows an embodiment of the present invention, in which 1
2 is a light emitting part, which includes a first light emitter 1a and a second light emitter 1b made of light emitting elements such as light emitting diodes, 2 is a dew condensing surface, and 3 is a light receiving part, in which light is emitted from a photoelectric detection element such as a photodiode. 4 is an amplifying section that includes first and second amplifiers 4a and 4b,
5 is the comparison section, which consists of operational amplifiers etc.
6 is a window glass plate such as a windshield of a vehicle, and 7 is a metal member.

Next, the operation of this embodiment will be explained.

The window glass plate 6 becomes foggy when the window glass plate 6 is cooled to below the dew point temperature of the air inside the vehicle due to the low outside air temperature. Therefore, if a metal member 7 with high thermal conductivity is embedded in the window glass plate 6, the low outside air temperature will be guided to the side surface of the passenger compartment.
The temperature of the side surface of the vehicle interior of the metal member 7 is lower than that of the surrounding window glass plate 6, and dew condensation is more likely to occur, so that it can be preferable as the dew condensation surface 2 for detection. By the way, if the vehicle is stopped at a place with an outside temperature of 0°C, no sunlight, and no wind, and the temperature inside the vehicle is adjusted to 25°C, the temperature of the dew condensation surface 2 for detection by the metal member 7 will be 12.5°C, and the surrounding The temperature is about 2° C. lower than the temperature of the side surface of the window glass plate 6 of the vehicle, and dew condensation can be detected quickly.

The light emitting unit 1 provided in the vehicle interior includes a first light emitter 1a that emits light in a first wavelength band and a second light emitter 1b that emits light in a second wavelength band. Here, the first wavelength band is a wavelength band that is easily absorbed by water (in this example, ultraviolet rays of 0.1 μm), and the second wavelength band is a wavelength band that is hardly absorbed by water (in this example, ultraviolet light is 0.1 μm). In this case, select infrared light (1.0 μm). Note that the transmission characteristics of water for light are as shown in FIG.

Then, the light emitted from the first light emitter 1a reaches the light receiving section 3 after being attenuated by both absorption by moisture (condensed water) adhering to the dew condensation surface 2 and scattering by dirt and the like. On the other hand, the second light emitter 1b
The light emitted from the dew condensation surface 2 is attenuated only by scattering due to dirt, etc., and reaches the light receiving section 3 with almost no attenuation due to moisture.

The light receiving section 3 includes a first light receiving body 3a that receives light from the first light emitter 1a, and a second light emitter 3b that receives light from the second light emitter 1b. The amount of light detected by the light receiving section 3 is determined by the amplifying section 4 using a first amplifier 4a and a second amplifier 4b whose amplification factor is set slightly smaller than that of the first amplifying section 4a.
They are each amplified, and a comparison section 5 compares the magnitude of the amount of received light.

The comparator 5 consists of a comparator 5a and a hunting prevention resistor 5b, and compares the levels of the output signals a and b of the amplifiers 4a and 4b, and generates a level "L" at the output out when a>b. , a level "H" is generated when a<b.

Therefore, first, the outputs of the first and second photoreceptors 3a and 3b are adjusted in advance so that they are approximately equal when no dew condensation occurs on the dew condensation surface 2.

Then, when there is no condensation on the dew condensation surface 2, even if dirt or the like occurs on the dew condensation surface 2 and the amount of light incident on the photoreceptors 3a and 3b changes, each light receiving body body 3a, 3
Since the ratio of the amount of light incident on b does not change, the output out is always at the level "L" at this time.

However, when condensation occurs on the condensation surface 2,
The effect of this condensed water appears only in the attenuation of the light in the first wavelength band (ultraviolet light in this embodiment) from the first light emitter 1a, so the output out is always at level "H" at this time. .

Therefore, according to this embodiment, even if dirt or the like occurs on the dew condensation surface 2 for detection, there is no risk of malfunction due to the condensation surface 2, and the occurrence of condensation can always be reliably detected. The present invention can be applied to air conditioners for commercial use to ensure accurate dehumidification control at all times.

Furthermore, FIG. 3 shows an embodiment of the present invention in which the dew condensation surface for detection and the light are made parallel, and the light dew of the first and second light reaching from the light emitting part 1 to the light receiving part 3 is transferred to the dew condensation surface. 2, and the other parts are the same as the embodiment shown in FIG.

According to the embodiment shown in FIG. 3, the optical path passing through the moisture due to dew condensation can be made long, and therefore a high degree of detection can be obtained.

〔Effect of the invention〕

As explained above, according to the present invention, even if dirt or the like occurs on the dew condensation surface for detection, there is no possibility of erroneous detection due to this, so the problems of the conventional technology can be sufficiently addressed. It is possible to easily provide a dew condensation sensor that can perform dew condensation detection with high reliability over a long period of time and is useful for accurate dehumidification control when applied to a vehicle air conditioner.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a dew condensation sensor according to the present invention, FIG. 2 is a characteristic curve diagram showing the light transmission characteristics of water, and FIG. 3 is a diagram of a detection section in another embodiment of the present invention. It is an explanatory diagram. 1... Light emitting part, 2... Condensation surface, 3... Light receiving part,
4...Amplification section, 5...Comparison section, 6...Window glass plate, 7...Metal member.

Claims (1)

[Claims] 1. A dew condensation sensor that includes first and second optical paths set to cross condensed water and detects the occurrence of dew condensation by comparing the light passing through the first and second optical paths. , a metal member embedded in a glass plate whose dew condensation is to be detected, first and second light emitters, first and second photoreceptors, and output signals of these first and second photoreceptors; is provided, the first optical path is formed between the first light emitter and the first light receiver, and the second light path is formed between the second light emitter and the second light receiver. It is characterized by being configured such that an optical path is formed, the dew condensation water is generated on the surface of the metal member, and the occurrence of dew condensation is detected by the output of the comparison means. Condensation sensor. 2. The dew condensation sensor according to claim 1, wherein the first and second optical paths are each formed to include a surface of the metal member as a reflective surface. 3. Claim 1 is characterized in that the first and second optical paths are each formed so as to pass near the surface of the metal member substantially parallel to the surface. Condensation sensor.