JPS6315809Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a device for detecting frost or dew condensation, and more particularly to a frost or dew condensation detection device using retroreflective optical means.

2. Description of the Related Art Conventionally, frost or dew condensation detection devices have been known in which a mirror surface is formed in a portion to be detected, and a light emitting element and a light receiving element are arranged at positions away from the mirror surface. The objective is to detect changes on the mirror surface due to frost or dew condensation by changes in the amount of reflected light. In this type of frost or dew condensation detection device, in order to improve detection accuracy, it is required to increase the angle of incidence of the incident light beam and the angle of reflection of the reflected light beam with respect to the mirror surface. This is to increase the influence on the intensity of reflected light by increasing the optical path length through the frost or dew in frost or dew conditions, and by allowing total internal reflection to occur within the frost or dew. .

However, in order to increase the angle of incidence of the incident light beam from the light projecting element and the reflection angle of the reflected light beam reflected by the mirror surface, the light projecting element and the light receiving element must be separated by a considerable distance. Therefore, a problem has arisen in that a considerably large space is required for the equipment in which the detection device is installed.

In order to overcome the above-mentioned problems, a frost or dew condensation detection device using retroreflective optical means is disclosed in unpublished Japanese Patent Application No. 102365/1983 of the same applicant. By using retroreflective optical means, the incident light beam and the reflected light beam are made parallel, thereby achieving close arrangement of the light projecting element and the light receiving element.

By the way, in both the conventional frost or dew condensation detection device using a normal mirror surface and the frost or dew condensation detection device using retroreflective optical means, if frost or dew condensation occurs in the part to be detected, At the same time, frost or dew was also attached to the light emitting element and the light receiving element. Therefore, there is a problem that the intensity of the incident light that enters the mirror surface or retroreflective optical means and the intensity of the reflected light that is received by the light receiving element decreases during frost or dew condensation, making accurate detection impossible. did. In particular, if changes in frost or dew condensation on the emitter and light receiver cannot follow changes in the frost or dew condensation on the surface to be detected, even if the frost or condensation on the surface to be detected disappears. However, there was a drawback that the amount of light received by the light receiving element remained reduced, making it difficult to even identify the state to be detected.

Therefore, the object of this invention is to eliminate the above-mentioned drawbacks and provide a frost or dew condensation device with excellent detection accuracy.

In summary, this invention consists of a retroreflective optical means formed on a substrate, a light emitting element and a light receiving element provided apart from the retroreflective optical means, and heating the light emitting element and the light receiving element. This is a frost or dew condensation detection device that detects frost or dew condensation based on changes in the amount of light received by a light receiving element.

As the "retroreflective optical means" used in this invention, for example, a retroreflective film consisting of a retroreflective spherical layer, which is put into practical use in road signs, etc., is used. Since the configuration of the retroreflective film is well known, detailed explanation thereof will be omitted. In this invention, a substrate on which retroreflective optical means are formed is placed on the surface to be detected. A light projecting element that is spaced apart from the retroreflective optical means and that projects light onto the retroreflective optical means and a light receiving element that receives light reflected from the retroreflective optical means are provided. Examples of the light emitting element and the light receiving element include
Well-known optical elements such as LEDs can be used. Up to this point, unpublished applications filed by the same applicant, patent applications filed in 1982,
- It is similar to the configuration disclosed in '10236.

A feature of this invention is that a heater is provided to heat the light projecting element and the light receiving element. The heater may be provided at any position that is advantageous for heating the light emitting element and the light receiving element. Preferably, a heater is formed of a transparent electrode made of, for example, tin oxide on the front surface of the light projecting element and the light receiving element, that is, on the side of the retroreflective optical means. By using a transparent electrode, the light projecting element and the light receiving element can be efficiently heated without blocking the passage of light. However, if you select the heater installation position or heater shape appropriately,
The heater may be constructed of opaque electrodes or the like. For example, when using an electrode having a gap through which incident light and reflected light pass, such as a comb-teeth electrode, it is possible to arrange it in front of the light projecting element and the light receiving element even if it is opaque.

In a preferred embodiment, a transparent window member is disposed in front of the light emitting element and the light receiving element, that is, on the side where the retroreflective optical means is present, and a transparent electrode is provided on the side of the light emitting element and the light receiving element of this window member. It is formed all over. Thereby, it is possible to heat the light projecting element and the light receiving element extremely effectively without having to worry about positioning the heater to ensure the optical path of the incident light and the reflected light.

As described above, according to this invention, since a heater is provided to heat the light emitting element and the light receiving element, even if dew or frost forms on the surface to be detected, the light emitting element and the light receiving element The surface is heated by the heat provided by the heater, so dew and frost are melted. Therefore, it is possible to accurately detect frost or dew condensation regardless of changes in the state of the surface to be detected.

An embodiment of this invention will be described below.

FIG. 1 is a perspective view of an embodiment of this invention.
FIG. 2 is a sectional view taken along line - in FIG. 1.

Referring to FIG. 1, a retroreflective spherical layer 2 is formed on a substrate 1 as a retroreflective optical means. Connecting parts 3 and 4 extend from the substrate 1, and the other ends of the connecting parts 3 and 4 are connected to a support part 7 that includes a light emitting element 5 and a light receiving element 6 (see FIG. 2).
is fixed. As is clear from FIG. 2, a transparent window member 8 is provided in the middle of the connecting parts 3 and 4, and a transparent electrode 9 as a heater is provided on the light emitting element 5 and light receiving element 6 side of the window member 8. is formed all over. Transparent electrode 9 may be made of a material such as tin oxide. Note that 10 is a hole for fixing the frost or dew condensation detection device of this embodiment to a device.

In the embodiment shown in FIGS. 1 and 2, the light projected from the light projecting element 5 is reflected by the retroreflective spherical layer 2, and the reflected light is received by the light receiving element 6. If frost or dew condensation occurs on the retroreflective sphere layer 2, the intensity of the reflected light will decrease due to cloudiness on the reflective surface of the retroreflective sphere layer. Therefore,
The amount of light received by the light-receiving element 6 decreases, thereby allowing frost formation or frost formation to be detected. In addition, since the transparent electrode 9 as a heater is formed facing the light emitting element 5 and the light receiving element 6, even if frost or dew condensation occurs, it is melted by heating, and both of the light emitting element 5 and the light receiving element 6 are There will be no frost or dew on the surface.

In this embodiment, since the retroreflective spherical layer 2 is used, the incident light and the reflected light are parallel, so it is not necessary to separate the light emitting element 5 and the light receiving element 6 as shown in FIG. Needless to say, they may be arranged close to each other.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of an embodiment of this invention. FIG. 2 is a sectional view taken along line - in FIG. 1. In the figure, 1 is a substrate, 2 is a retroreflective sphere layer as retroreflective optical means, 5 is a light projecting element, 6 is a light receiving element, and 9 is a transparent electrode as a heater.

Claims (1)

[Claims for Utility Model Registration] Retroreflective optical means formed on a substrate; a light emitting element and a light receiving element provided apart from said retroreflective optical means; and said light emitting element and light receiving element. A frost or dew condensation detection device, comprising a heater for heating, and detects frost or dew condensation based on a change in the amount of light received by the light receiving element.