JPH0718287U - Light receiving element of vehicle-mounted laser radar - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a light receiving element for laser radar, which is inexpensive to manufacture, consumes less power, and has high operating speed and reliability. [Constitution] The light receiving element (1) such as APD is a silicon substrate.
It has a substantially rectangular light receiving surface (1a) having a shape similar to the detection area formed on (1b) and the like. According to a preferred example, the light receiving surface (1a) has an aspect ratio of about 1: 2, and its four corners are curved.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a light receiving element of a vehicle-mounted laser radar, and more particularly to a light receiving element having a rectangular detection area and a light receiving surface having a similar shape.

[0002]

[Prior art]

 A laser radar is used as one of vehicle-mounted radar devices. This laser radar emits a steep pulsed laser light from a laser head composed of a semiconductor laser diode and a light-transmitting lens, and reflects the reflected light reflected by an object such as a preceding vehicle back to an avalanche photodiode. By receiving at the light receiving part mainly composed of a light receiving element such as (APD) and dividing the half of the time required from receiving the laser light to receiving the reflected light by the propagation speed (light speed) of the laser light, It is configured to detect the distance to the object that caused the reflection.

The detection area of the on-vehicle laser radar is a rectangular shape with a width of about 8 m, which is about the lane width, and a vertical width of about 4 m, which is about the maximum height of the vehicle, at a distance of about 100 m (meter). Is considered optimal. If the detection area is too large for the on-vehicle laser radar, there is the inconvenience of detecting reflected light from vehicles in adjacent lanes that do not need to be detected. Therefore, as shown in FIG. 3, the shape of the light receiving surface on which the reflected light generated in this detection area is imaged by using the convex lens has an aspect ratio of 1: 2 (h: w = 1: 2) similar to that of the detection area. It is necessary to have a horizontally long rectangular shape.

Conventionally, a general-purpose light receiving element such as an APD has a circular shape. Therefore, in order to form an image only in the detection area on the light receiving surface using the light receiving lens, a slit having a horizontally long opening with an aspect ratio of about 1: 2 that is similar to the detection area can be formed on the light receiving surface of the APD. It is necessary to place them as close as possible. For example, as shown in FIG. 4, it is necessary to bond and fix a slit 12 having a horizontally long opening 12a having an aspect ratio of about 1: 2, which is similar in shape to the detection area, onto the light receiving surface 11 of the APD.

[0005]

[Problems to be solved by the device]

 In the light-receiving element combined with the slit shown in FIG. 4, a considerable part of the peripheral portion of the light-receiving surface of the APD is an ineffective region that does not contribute to the photoelectric conversion operation. Such an ineffective region is not only wasteful in terms of manufacturing cost and power consumption, but also lowers the manufacturing yield, its junction capacitance lowers the operation of the element, and the entire element There is a problem of reducing reliability.

[0006]

[Means for Solving the Problems]

 The light receiving element of the in-vehicle laser radar according to the present invention has a substantially rectangular light receiving surface that is similar in shape to the detection area. According to a preferred embodiment of the present invention, the light receiving surface of the light receiving element has an aspect ratio of approximately 1: 2, and its four corners are curved.

[0007]

[Action]

 If the light-receiving surface of the light-receiving element has a substantially rectangular shape that is similar to the detection area, there will be no ineffective area that does not contribute to the photoelectric conversion operation, which will reduce manufacturing costs and power consumption, as well as the manufacturing yield and Both the operating speed and the reliability of the entire device are improved.

[0008]

【Example】

 FIG. 1 is a plan view showing the structure of a light receiving element of a vehicle-mounted laser radar according to an embodiment of the present invention. The light receiving element 1 is composed of an APD 1a formed in the central portion of a silicon substrate 1b. The formation region of the APD 1a forms a rectangular light receiving surface having an aspect ratio of about 1: 2. The four corners of the APD 1a forming this light receiving surface are drawn with gentle curves in order to avoid the concentration of the electric field at these points and to stabilize the operation and improve the reliability.

FIG. 2 is a perspective view showing a state where the light receiving element 1 of FIG. 1 is accommodated in the case. The light receiving element 1 is positioned and fixed on the base 1 of the case having the lead wire with an adhesive, and the tip of the lead wire and the light receiving element are connected by the metal foils 2a and 2b, and then the glass window 3a. The structure is such that the lid 3 of the case that has been fitted is attached to the periphery of the base 2.

Although the case where the APD is used as the light receiving element has been described above, the present invention can be applied to a normal photodiode.

[0011]

[Effect of device]

 As described in detail above, the light receiving element of the in-vehicle laser radar according to the present invention has a substantially rectangular shape whose light receiving surface is similar to the detection area, and therefore does not contribute to the optical / electrical conversion operation. The area is gone. Therefore, the manufacturing cost and power consumption are reduced, and the yield, the operating speed, and the reliability of the entire device at the time of manufacturing are improved. Further, the light receiving element of the present invention has an advantage that a slit for defining the detection area is not necessary.

[Brief description of drawings]

FIG. 1 is a plan view of a light receiving element of an in-vehicle laser radar according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a state where the light receiving element of FIG. 1 is housed in a case.

FIG. 3 is a conceptual diagram for explaining a detection area of an in-vehicle laser radar.

FIG. 4 is a plan view showing a configuration of a light receiving element of a conventional vehicle-mounted laser radar.

[Explanation of symbols]

 1 Light receiving element 1a Light receiving surface on which APD is formed 1b Silicon substrate

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Shigeru Nagago 1168 Suwa, Takashi-ku, Kawasaki-shi, Kanagawa 1168 Takadakata (72) Hidefumi Ito 1-20-13 Himonya, Meguro-ku, Tokyo Himawari-so No. 15 (72) Devised Person Takashi Yoshimura 1-11-20 Irie, Kanagawa-ku, Yokohama-shi, Kanagawa 104 Maison Kotobuki

Claims (3)

[Scope of utility model registration request] 1. A light-receiving element for a vehicle-mounted laser radar, which has a substantially rectangular light-receiving surface that is substantially similar to the detection area. 2. The light-receiving element for a vehicle-mounted laser radar according to claim 1, wherein the light-receiving surface has an aspect ratio of approximately 1 to 2. 3. The light-receiving element of a vehicle-mounted laser radar according to claim 1, wherein the four corners of the light-receiving surface are curved.