JPH0579907A - Solar radiation sensor - Google Patents

Abstract

PURPOSE:To provide a flat output characteristic not affected by solar radiation altitude at a low production cost. CONSTITUTION:A light receiving element 1 is formed on a substrate 3, and a semi-transparent, circular cover body 2 made of a single material is provided to cover the light receiving element 1. The cover body 2 has an apex directly above the center of the light receiving element 1, a curve shape gradually inclined downward toward the outer periphery is formed, its thickness is made thick at the center section 22 and thin at the outer periphery section 21, and the light permeability of the center section 22 is set to 0.6-0.9 of the light permeability of the outer periphery section 21. The change of the sensor sensitivity due to the solar radiation altitude is offset by the change of the light permeability, and a flat output characteristic is provided. The cover body 2 can be manufactured via the integral molding by a press at a low production cost.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solar radiation sensor, and more particularly to a solar radiation sensor capable of obtaining a flat solar radiation amount output regardless of the solar radiation height.

[0002]

2. Description of the Related Art A light receiving element such as a PIN type amorphous Si photodiode can obtain a photocurrent output that is linear with respect to the amount of solar radiation as shown in FIG. 6, and the amount of solar radiation can be detected by detecting this photocurrent. Can be known quantitatively.

When a solar radiation sensor for air conditioning of a vehicle is constituted by such a light receiving element, the angle of solar radiation with respect to the light receiving surface, that is, the solar radiation height, changes momentarily due to changes in the angle of sunlight itself or changes in the posture of the vehicle. Currently commercially available light receiving elements have the highest sensitivity to light that is incident perpendicularly to the light receiving surface, and even if the amount of solar radiation is the same, the sensitivity gradually decreases and an error occurs in the output.

Therefore, for example, Japanese Patent Laid-Open No. 61-210915.
In the publication, it is attempted to obtain a flat characteristic that is not affected by the solar radiation height by applying a light-shielding paint or attaching a light-shielding tape to the center of the sensor cover.

[0005]

However, in the above-mentioned conventional structure, there is a problem that the manufacturing cost is high because it is necessary to apply or attach another material to the sensor cover.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a solar radiation sensor which is simple to manufacture and has flat output characteristics.

[0007]

The structure of the present invention will be described. A light receiving element 1 and a semitransparent circular cover body 2 which covers the light receiving element 1 and is made of a single material are provided. Has a top just above the center of the cover, and is shaped into a curved surface that gradually slopes downward toward the outer periphery, and the wall thickness of the cover body 2 is made thicker at the center and thinner at the outer periphery, and The transmittance is set to be 0.6 to 0.9 with respect to the light transmittance of the outer peripheral portion.

[0008]

In the solar radiation sensor having the above structure, the light transmittance of the semitransparent cover body 2 is set in the above range to reduce the light transmittance in the central portion and increase the light transmittance in the outer peripheral portion. The change in sensor sensitivity is offset by the change in light transmittance, and a flat output characteristic is obtained.

Since the present invention only needs to change the wall thickness of the cover body 2 made of a single material, it can be easily manufactured by press molding or the like, and the manufacturing cost can be greatly reduced.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, P is formed at the center of the upper surface of a circular substrate 3.
A light receiving element 1 is provided by laminating amorphous Si films so as to form an IN-type photodiode, and lead wires 11 and 12 from the light receiving element 1 are drawn out through the inside of a downward protruding portion 31 of the substrate 3. There is.

The upper part of the light receiving element 1 is covered with a cover body 2. The cover body 2 has a circular shape, and the outer surface thereof is the light receiving element 1.
It has a curved surface that is a peak directly above the center of the, and smoothly inclines downward from this. The inner surface of the cover body 2 is substantially parallel to the outer surface at the outer peripheral portion 21, and is a substantially horizontal plane at the central portion 22 which slightly decreases toward the center. Thus, the thickness of the cover body 2 is as thin as d1 at the outer peripheral portion 21 and as thick as d2 at the central portion 22.

The cover 2 is made of a single translucent resin material,
For example, a black dye is appropriately mixed with polycarbonate to make it semi-transparent, and as shown in FIG. 2, 600 in the range of 400 nm to 800 nm, which is the sensitive region of the light receiving element, is used.
The light transmittance rises in nm, and the light transmittance T1 of the outer peripheral portion 21 whose wall thickness d1 is set to 1 mm is 75% and the wall thickness d2 is 2 mm.
The light transmittance T2 of the central portion set to is 60%.

The outer peripheral portion 21 and the central portion 2 where the wall thickness starts to change
The boundary position of 2 determines the ratio of the light rays incident on the light receiving element 1 through the outer peripheral portion 21 or the central portion 22 of the cover body 2 at a certain insolation altitude. The intersection of the line that forms an angle of 40 ° with the end face of the light receiving element 1 and the cover body 2 is defined.

The cover body 2 can be easily formed by press molding or the like, and the space 2 covered with the cover body 2 is formed.
A material with a high refractive index, for example, silicone is filled in a.

Thus, the central portion 2 with respect to the outer peripheral portion 21
Assuming that the light transmittance ratio of 2 is 0.8, the change in sensor sensitivity, which increases as the solar radiation height increases, is offset by the decrease in the light transmittance, and as shown in FIG. Is in the range of 40 ° to 90 ° and becomes flat without depending on the solar radiation height.

In this case, when the light transmittance ratio is 0.9 or more, the flat characteristics disappear in the range of 40 ° to 60 ° as shown in FIG. 4, and when the light transmittance ratio is 0.6 or less. As shown in FIG. 5, the photocurrent is significantly reduced in a region where the solar radiation height is high, and the flat output characteristic is not exhibited.

By filling the space 2a in the cover body 2 with silicone, even if the light reaches the inner surface of the cover body 2 at a large incident angle, the light efficiently enters the light receiving element without being reflected. Therefore, the cover body 2 The height H can be kept low, and the appearance of the vehicle can be improved.

[0018]

INDUSTRIAL APPLICABILITY As described above, the solar radiation sensor of the present invention can be manufactured at low cost, has a flat output characteristic that is not affected by the solar radiation altitude, and can be suitably used as a sensor for vehicle air conditioning control.

[Brief description of drawings]

FIG. 1 is an overall sectional view of a solar radiation sensor.

FIG. 2 is a graph showing a light transmittance characteristic of a cover body material.

FIG. 3 is a graph showing an output characteristic of a sensor according to an embodiment of the present invention.

FIG. 4 is a graph showing an output characteristic of a sensor in a comparative example.

FIG. 5 is a graph showing output characteristics of a sensor in a comparative example.

FIG. 6 is a graph showing the output characteristics of the sensor with respect to the amount of solar radiation.

[Explanation of symbols]

 1 light receiving element 2 cover body 3 substrate

Claims (1)

[Claims] 1. A light-receiving element and a semi-transparent circular cover body that covers the light-receiving element and is made of a single material. The cover body has a top directly above the center of the light-receiving element, and gradually extends toward the outer periphery. The cover body is formed into a curved surface that slopes downward, and the thickness of the cover body is made thicker in the central portion and thinner in the outer peripheral portion so that the light transmittance of the central portion is 0.6 to 0 relative to the light transmittance of the outer peripheral portion. A solar radiation sensor characterized by being set to 0.9.