JPS61198830A - Photodetector - Google Patents

Abstract

PURPOSE:To widen the directivity of the titled detector by arranging photodetectors toward the outside of the optical axis of each lens even when plural optical lenses are arranged on one plane. CONSTITUTION:When a light is made incident on a photodetector from the horizontal direction, the light incident on an optical lens 31 is collected at a focal point 31f and made incident on a photodetector 33, and the light incident on the optical lens 32 is collected to a focal point 32f and made incident on a photodetector 34. On the other hand, when the light is made incident on the photodetector from upward direction, since the light incident from the upward on the optical lens 31 is collected to a position 31a, the light is not made incident on the photodetector 33, and the light incident on the optical lens 32 is collected to a position 32a and made incident on the photodetector 34. When the light is made incident on the photodetector downward, since the light incident on the optical lens 32 downward is collected to a position 32b, the light is not made incident on the photodetector 34 and the light made incident on the optical lens 31 is collected to a position 31b and made incident on the photodetector 33. Thus, even when the optical lenses are arranged on one plane, the directivity is made spread.

Description

[Detailed description of the invention] [Technical field of invention] The present invention relates to a light receiving device with wide directivity.

[Prior Art and Its Disadvantages] A conventional light-receiving device composed of a set of an optical lens and a light-receiving element was constructed as shown in FIG.

In this light receiving device, the center of the light receiving element 11 was arranged to align with the optical axis 13 of the optical lens 12.

Here, if the light-receiving element 11 is placed at the focal position of the optical lens 12, the directivity of the light-receiving device is ±tan''' (D/2 f ).Furthermore, f is the focal length of the optical lens 12, and D is the effective area of the light receiving element 11.In other words, in order to widen this directivity, it was necessary to shorten the focal length f of the optical lens 12 or increase the effective diameter of the light receiving element 11.However, the focal length A large and short optical lens 12 has the disadvantage that the effective lens area becomes small and the amount of light received decreases, and a light receiving element with a large effective diameter is expensive.

Next, referring to FIG. 6, a case will be described in which two sets of optical lenses and light receiving elements are provided to improve directivity. In this case, the optical lenses 21 and 22 are arranged so that their optical axes are at a constant angle e. By doing this, the directivity due to the optical lens 21 and the light receiving element 23 and the directivity due to the optical lens 22 and the light receiving element 24 are changed, and it is possible to obtain a directivity approximately twice that of the light receiving device shown in FIG. . However, the light receiving device in Fig. 6 has optical lenses 21 and 22.
Since the lens is not placed on a flat surface, it was necessary to use two lenses.

[Object of the Invention] The present invention has been made in view of the above points, and its purpose is to provide a light receiving device in which optical lenses are disposed on the same plane and has wide directivity.

[Key Points of the Invention 1] The directivity of the device is expanded by arranging the light-receiving elements so as to be shifted toward the outside of the device with respect to the optical axes of a plurality of optical lenses arranged on the same plane.

[Embodiment of the Invention] A light receiving device according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a light receiving device using two sets of optical lenses and light receiving elements. In FIG. 1, 31.
32 are optical lenses. The above optical lens 31
．． The focal positions of 32 are 31f and 32f, respectively. At this focal position 31f, a light receiving element 33 corresponding to the optical lens 31 is disposed with its center position shifted outward from the optical axis 3112, that is, in the six directions of the arrows, and at a focal position 32f, a light receiving element 33 corresponding to the optical lens 32 is disposed. The light receiving element 34 is arranged with its center position shifted outward from the optical axis 32λ, that is, in the direction of arrow B.

Next, the operation will be explained. First, the case where light enters the light receiving device shown in FIG. 1 from the horizontal direction will be described with reference to FIG. 2(A). In this case, the light incident on the optical lens 31 is focused on the focal point position 31f and is incident on the light receiving element 33. Further, the light incident on the optical lens 32 is focused on a focal point position 32f and is incident on the light receiving element 34.

On the other hand, a case where light enters the light receiving device shown in FIG. 1 from above will be described with reference to FIG. 2(B). In this case, the light incident on the optical lens 31 from above is at position 3.
Since the light is focused on 1a, it does not enter the light receiving element 33. Further, the light incident on the optical lens 32 is focused at a position 32a and is incident on the light receiving element 34.

Further, a case in which light enters the light receiving device shown in FIG. 1 from below will be described with reference to FIG. 2(C). In this case, the light incident on the optical lens 32 from below is at position 3.
Since the light is focused on 2b, it does not enter the light receiving element 34. Further, the light incident on the optical lens 31 is focused at a position 31b and is incident on the light receiving element 33.

In this way, even when optical lenses are arranged on the same plane, their directivity can be expanded.

In addition, in the above embodiment, the optical lens and the light receiving element are
Although it has been explained that the directivity in the vertical direction is expanded by using four optical lenses 41 to 44 and four light receiving elements 51 to 54 each, as shown in FIG. You may try to spread it out. In Figure 3, 41
f to 44f indicate the focal positions of the optical lenses 41 to 44, respectively, and the light receiving elements 51 to 54 are arranged outwardly shifted from the focal positions 41f to 44f, respectively.

Furthermore, in the embodiment shown in FIG.
were arranged at the focal positions 31f and 32f of the optical lenses 31 and 32.
), move the light receiving elements 31 and 32 to the focal position "31f".
, 32f may be shifted forward or backward.

[Effects of the Invention] As detailed above, according to the present invention, even when a plurality of optical lenses are arranged on the same plane, the position of the light receiving element is shifted to the outside of the optical axis of each lens. It is possible to provide a light receiving device that can expand the directivity of the device.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a light receiving device according to an embodiment of the present invention;
Figures 2 (A) to (C) are diagrams showing the optical path when the direction of light incident on the same device changes, Figure 3 is a diagram showing another embodiment of the present invention, and Figure 4 ( A) and (B) are diagrams showing modifications of the above-mentioned embodiment, and FIGS. 5 and 6, respectively.
Each figure shows a conventional light receiving device. 31, 32... Optical lens, 33.34... Light receiving element. Applicant's agent Patent attorney Takehiko Suzue Figure 1A. Figure 2 Figure 3 Figure 41! I

Claims (1)

[Claims] 1. A light-receiving device comprising: a plurality of optical lenses arranged on the same plane; and a light-receiving element arranged outwardly of the device with respect to the optical axis of each optical lens.