JPS6183921A - Illuminometer - Google Patents

Abstract

PURPOSE:To obtain the photo detection angle characteristic complying with the cosine law, by providing one or more photo detection angle characteristic correcting apertures on the side of a photo detector. CONSTITUTION:Light incident from the top (x) of a light diffusion plate 3 reaches a photoelectric conversion element 7 passing sequentially through a magnifying filter 5 and a view angle correction filter 6 to be converted into electricity. As the photo detection angle grows larger to 90 deg., incident light from the top (x) of the light diffusion plate 3 decreases too much to maintain the photo detection angle characteristic complying with the cosine law. But when provided on the side of the substrate 4, an aperture 8 allows light to reach the BD surface incident from the AC surface so that the photo detection characteristic is corrected with respect to the photo detection angle near 90 deg.. In this manner, the photo detection angle characteristic can be obtained which the light receiving surface composed of the substrate 4 and the light diffusion plate 3 is flat while precisely complying with the cosine law.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an illuminance meter having a light receiver whose light receiving angle characteristics have been corrected.

(Conventional column) 1. Composition and Problems There are two important characteristics that an illuminance meter should have. One is that the spectral sensitivity characteristics of the light receiver match the standard luminous efficiency;
The other is that the light receiving angle characteristics of the light receiver match the cosine law. The latter cosine law can be expressed as shown in Figure 4. In Fig. 4, if the angle between the perpendicular to the center of the light-receiving surface and the incident light is the light-receiving angle θ, then the sensitivity of the light receiver changes by C05θ as the light-receiving angle changes, which is said to follow the cosine law.

The light receiver of the illuminance meter usually has a light diffusing plate placed on top of the photoelectric conversion element so that the above-mentioned light receiving angle characteristics match the cosine law. When the shape of this light diffusing plate is (total), the better the diffusivity is, the more it approximates the cosine law as shown in Figure 6. However, even when the best diffusivity is used, the shape of the light-receiving surface is flat and located on the same plane or lower than the surrounding substrate, the acceptance angle is 900°.
As the value approaches , the deviation of the acceptance angle characteristic from the cosine law increases. In order to improve this problem, various improvements have been made to the shape of the light diffusing plate and the substrate around it.

For example, as shown in Figures 6a and 6h, the shape of the light diffusing plate can be changed from a flat surface to a three-dimensional shape, and the light receiving angle characteristics around 90' can be improved by raising the diffusing plate higher than the surrounding substrates. I know. However, by lifting the light diffusing plate above the substrate, the indicated value at around 90° may not become zero. In addition, if the light diffusing plate is three-dimensional,
Since the distance from the light source changes depending on where the measurement reference plane is located on the light diffusing plate, a problem arises in the reliability of the single illuminance. Furthermore, the surface of the light diffusing plate may be scratched during measurement and storage, which may adversely affect the light receiving angle characteristics.

OBJECTS OF THE INVENTION The present invention solves these conventional problems, and provides an illuminometer light receiving device in which the light diffusing plate is located on the same plane as the substrate or at a position lower than this, and has a receiving angle characteristic that conforms to the cosine law. The purpose of this is to provide the following information.

Structure of the Invention The present invention provides an illumination meter light receiving unit which is composed of a substrate of the illumination meter light receiving section, a light diffusing plate located on the same plane as the substrate or a plane lower than this, and one or more apertures provided on the side surface of the substrate. With this, it is possible to obtain light receiving angle characteristics that exactly match the cosine law.

DESCRIPTION OF EMBODIMENTS FIG. 1 shows a cross-sectional structure of an illuminance meter receiver in an embodiment of the present invention. In Fig. 3, 3 is a light diffusing plate, 4
5 is a magnification filter, 6 is a visibility correction filter, and R is a photoelectric conversion element. Further, 8 is an aperture.

As shown in Figure 4, the illumination meter receiver is
The incident light passes sequentially through a magnification filter 5 and a visibility correction filter 6, reaches a photoelectric conversion element 7, and is photo-electrically converted. As the acceptance angle increases and approaches 90', the incident light from the top surface X of the light diffusing plate decreases, making it no longer possible to maintain acceptance angle characteristics according to the cosine law. However, providing an aperture 8 on the side of the substrate Therefore, the light enters from the AC surface, and the BD
From there, it reaches the photoelectric conversion element 7 through the diffuser plate, and can play the role of correcting the light receiving angle characteristics for the light receiving angle around 90'. In the aperture 8 of FIG. 1, CB is located parallel to the upper surface X of the light diffusing plate. The inner wall of the aperture will be painted matte black. This results in
The light incidence for a light receiving angle of 90° is assumed to be zero. Also,
The larger the length of AC with respect to Bp, the more correction can be made for the small angle of acceptance or C).

FIG. 2 shows an external view of the light receiver. In FIG. 2, 4 is a substrate, 3 is a light diffusing plate, and 8 is an aperture. The apertures are arranged in one row on the side of the receiver, but two or more rows can also be arranged in a brick-like arrangement. Alternatively, as shown in FIG. 3, a plurality of apertures may all be connected and a transparent optical material 9 may be inserted into this portion. This also makes it possible to correct the light receiving angle characteristics.

Effects of the Invention The illumination meter receiver according to the present invention is equipped with an aperture for correcting the angle of acceptance characteristics on the side, so that the acceptance surface made up of the substrate and the light diffusing plate is flat and precisely conforms to the cosine law. It has light receiving angle characteristics and is extremely useful as a light receiver for illumination meters.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an illuminometer light receiving section according to the present invention, FIG. 2 is an external view of an illuminance meter light receiving section according to an embodiment of the present invention, and FIG. 3 is an illuminance meter light receiving section according to another embodiment of the present invention. Figure 4 is an exaggerated diagram of the acceptance angle characteristics according to the cosine law, Figure 5 is a diagram of the acceptance angle characteristics of the illumination meter receiver due to differences in diffusivity, and Figure 6
The figure is an R-side view of a conventional illuminance meter light receiving section. 3... Light diffuser plate, 4... Light receiver substrate, 7... Mountain... Photoelectric conversion element, 8... Mark... Aperture. Name of representative PII Patent attorney Toshio Nakao 1 person Figure 3 (a,) Light reception, 1IilliL (θ)

Claims (1)

[Claims] An illuminance meter that has one or more apertures on the side of the receiver for correcting the receiving angle characteristics.