JPH01316618A - Optical sensor - Google Patents

Abstract

PURPOSE:To reduce the incident angle dependency of the incident light quantity of the title optical sensor so that accurate light quantity measurement can be performed by providing a light intercepting or totally reflecting means to a condenser lens. CONSTITUTION:When the angle of incidence is 0 deg., most of light rays are intercepted by an intercepting section 9 and do not reach the light transmissive window 7 of a photodetector. When the angle of incidence is 45 deg., part of the light rays reaching the window 7 is intercepted. When the angle of incident is 90 deg., moreover, most of the light rays do not hit the section 9, but reach the window 7, because the light rays are largely refracted at the surface of a condenser lens 5 on the light source side. As a result, the detecting quantity of the light at a low angle of incidence decreases and that of the light at a high angle of incidence relatively increases. In other words, the difference in the detecting light quantity by the angle of incidence can be reduced and more accurate measurement can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a visible light sensor and an infrared light sensor used to control the operation of each Wi device and to measure the environment.

Prior art A conventional optical sensor of this type is disclosed in Japanese Patent Application Laid-Open No. 62-26102.
As shown in the No. 5 bulletin, the structure was as shown in Figure 9. In FIG. 9, 1 is a condenser lens, 2 is a photodetector, 3 is a light transmission window, and 4 is a photodetector element. The condensing lens 1 transmits light incident perpendicularly to the photodetector 2 without refracting it, greatly refracts light with a large angle of incidence, and transmits light from all directions to the photodetector 2. It is designed to be incident.

Problems to be Solved by the Invention However, in the above configuration, most of the light incident from the vertical direction of the light transmission window 3 is detected.

- Light incident from the horizontal direction is bent by the condenser lens 1, and a portion of it reaches the light transmission window 3, but the amount is very small. Figure 10 shows detection based on the incident angle when the amount of irradiated light is constant. FIG. 2 is a diagram showing changes in light amount. When the incident angle is 0 degrees, that is, the detected amount of light on the optical axis of the condensing lens is 100, the incident angle is 90 degrees, that is, from the horizontal direction of the light transmission window 3. When it is incident, the value is close to 0.In other words, when a conventional concave lens composed of a spherical surface is used as a condenser lens, the amount of detected light is highly dependent on the angle of incidence (and accurate measurement of the amount of light is extremely difficult). In view of the above problems, the present invention provides an optical sensor that can reduce the dependence of the detected light amount on the angle of incidence and perform more accurate measurements.

Means for Solving the Problems In order to achieve the above object, the optical sensor of the present invention is provided with means for blocking or totally reflecting incident light in a part of the condensing lens.

Effect: With this configuration, light is blocked or reflected at locations where there is a large amount of incident light, so that the amount of light reaches the photodetector uniformly.

EXAMPLE An example of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of an optical sensor in a first embodiment of the present invention. In the figure, 5 is a condenser lens, 6 is a photodetector, 7 is a light transmission window, and 8 is a photodetector element. An axially symmetrical light shielding part 9 is located on the optical axis of the condensing lens 5, and as shown in FIG. 9 and does not reach the light transmission window 7 of the photodetector 6. Furthermore, as shown in FIG. 2(b), a portion of the light rays that reach the light transmission window 7 are blocked at an incident angle of 45 degrees. Furthermore, Figure 2 (C
), when the incident angle is 90 degrees, the light rays are largely refracted by the light source side surface of the condenser lens 5, so most of them reach the light transmission window 7 without hitting the shielding part 9. As a result, the detected amount of light at a low incident angle becomes small (and the detected amount of light at a high incident angle becomes relatively large). In other words, the difference in the detected light amount depending on the incident angle can be made small.

A second embodiment of the present invention will be described below with reference to the drawings. FIG. 3 is a configuration diagram of a condensing lens of an optical sensor showing a second embodiment of the present invention. In the same figure, the first
The difference from the figure is that the condenser lens is made of the same material and uses total internal reflection to achieve the same effect as a shield. In the figure, 10 is a surface of the condensing lens on the light source side, 11 is a total reflection part located within the plane of the condensing lens on the image plane side, and 12 is a spherical part on the image plane side of the condensing lens. The functions of the condensing lens of the optical sensor configured as described above will be explained. FIGS. 4(a), (b), and (c) show how light rays reach the light transmission window 7 at each incident angle. When the incident angle is small, the light rays do not reach the light transmission window 7 due to the total reflection section 11, and only the light rays incident from the spherical surface section 12 reach the light transmission window 7.

As shown in FIGS. 4(b) and 4(c), most of the light rays having an incident angle of medium or higher reach the light transmitting window 7, including the light rays incident on the total reflection section 11 and the spherical surface section 12. Moreover, since the light beam incident from the total reflection section reaches the light transmission window 7 at a smaller angle of incidence than the light beam incident from the spherical surface section 12, the detection efficiency is improved. As a result, it is possible to realize an optical sensor with small incidence angle dependence using some lenses with a simple structure made of the same material. In this embodiment, the total reflection section 11 is provided only at one location on the optical axis, but it may be provided at multiple locations, even if not on the optical axis.

Next, a third embodiment of the present invention will be described with reference to the drawings. FIG. 5 shows a condensing lens of an optical sensor showing a third embodiment of the present invention. In the figure, 13 is a condenser lens, 14 is a light source side surface of the condenser lens 13, 15 is a curved surface of the condenser lens 13 on the image plane side, and 16 is a surface of the condenser lens 13 on the image plane side.

The functions of the condensing lens of the optical sensor configured as described above will be explained. Most of the light rays at low incident angles pass through the light source side surface 14 and the image surface curved surface 15.
4 and the field surface curved surface 15 form a concave lens with a small radius of curvature, and the incident light is thick (spread) and the amount of light hitting the light transmission window 7 is reduced.

On the other hand, light rays with high incident angles
The traveling direction of the light beam is widened (bend) so that it hits the light transmission window 7 at a low angle of incidence, and the absolute amount of light is small (but it is possible to detect the light amount efficiently).

FIG. 6 is a sectional view of a main part of an optical sensor according to a fourth embodiment of the present invention. This embodiment has almost the same configuration as the first embodiment, but the first difference is that the light shielding part 17 is disposed on the image plane side.
This is different from the embodiment. FIGS. 7 and 8 show the fifth aspect of the present invention. FIG. 7 is a sectional view of a main part of an optical sensor in a sixth embodiment. This embodiment has almost the same configuration as the second embodiment, but differs from the second embodiment in that in addition to the total reflection section 11, a light shielding section 18 and a flat surface section 19 for low incidence angles are provided. be. Fifth. According to the sixth embodiment, more effects than the second embodiment can be obtained. In addition, in Fig. 8, 2
Reference numeral 0 denotes a side surface, which is composed of a plurality of surfaces without using a spherical surface, each of which allows light rays with different incident angles to efficiently reach the light transmission window 7.

Effects of the Invention As described above, according to the present invention, the dependence of the incident light amount on the angle of incidence can be reduced by providing a light shielding or total reflection means on the condenser lens, so that accurate light amount measurement can be performed.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a photosensor according to a first embodiment of the present invention;
2(a) to 2(c) are diagrams showing the state of incident light entering the condensing lens of the same sensor, and FIG. Figure 4(a)~
(c) is a diagram showing the state of incident light incident on the condensing lens in the same embodiment, and FIGS.
FIG. 9 is a cross-sectional view of a conventional optical sensor, and FIG. 10 is a diagram showing the relationship between the amount of light and the angle of incidence of the same sensor. 5...Condenser lens, 6...Photodetector,
7...Light shielding window, 8...Photodetection element, 9...Name of the attorney for the light shielding department: Patent attorney Toshio Nakao and one other person Figure 1 T-- - Figure 2, Figure 2, Public repulsion. Figure 3 Figure 4 Figure 4 (C) Brown e i--- C()

Claims (3)

[Claims] (1) It has a photodetector and a condensing lens provided on the light source side of the photodetector, and a light shielding means for blocking the light emitted from the light source is provided in a part of the condensing lens. light sensor. (2) The optical sensor according to claim 1, wherein a part of the condensing lens is provided with a total reflection surface that totally reflects the incident light. (3) An optical sensor that includes a photodetector and a condensing lens provided on the light source side of the photodetector, and a part of the condensing lens is provided with a total reflection surface that totally reflects incident light.