JPS58193427A - Light receiving device - Google Patents

Abstract

PURPOSE:To extend the reaching distance of infrared rays, by providing a constitution wherein the back surface of an attaching part to which an infrared ray receiving element is attached is covered by a metal case and the front surface is opened, widening the incident angle to the light receiving element, and increasing the amount of the incident light. CONSTITUTION:A PIN photodiode 13 made of plastic mold, which is a infrared ray receiving element, is attached to the front surface of a printed substrate 11 in parallel with the substrate 11. Circuit parts constituting an amplifier are attached to the substrate at the same time. A plurality of projections 17, which are provided on a metal case 12, are inserted into holes 18 of the substrate 11 and soldered. Thus, only the back surface of the substrate 11 is covered by the case 12.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a light receiving device in a remote control device using infrared rays.

Recently, the price of remote control devices using infrared rays has decreased,
Television receiver 1. It has come to be used in various things such as video tape recorders. When using this device it is important that it can be controlled from as far away as possible.

The present invention is intended to extend this reach.

First, a conventional example will be explained. FIG. 1 shows an example of conventional implementation. Due to the recent development of devices, a PIN photodiode is used as the infrared receiving device 3. A hole 2 is made in the light-receiving surface side of the metal case 1 that covers the PIN photodiode 3, and it receives infrared rays (a wavelength of approximately 9600 i is used) emitted from a transmitter (not shown) of a remote control device. It is then converted into an electrical signal, amplified, and used. FIG. 3 shows a block diagram of the configuration of this light receiving section. Since the optical-to-electrical conversion signal obtained from the PIN photodiode or the like which is the infrared light receiving element 3 is weak, the amplifier 4 in the subsequent stage is required to have a high gain. Because of its high gain, it is also susceptible to interference from peripheral circuits. In order to shield it, a metal case 1 as shown in FIG. 1 is used.

FIG. 2 shows an explanatory diagram of light reception. The infrared rays from the transmitter are
In order to enter the light receiving element 3 through the hole in the metal case 1,
The reach distance is determined by the aperture angle θ shown in FIG.

On the other hand, the PIN photodiode itself, which is a light-receiving element, has recently ranged from metal-cased ones to plastic-molded ones. The metal case has a light-receiving surface that can only be received in one direction, but the plastic-molded Monoke light-receiving surface is sensitive not only to the front but also to light received from the back and other surfaces.

The present invention focuses on the fact that this plastic-molded light-receiving element has sensitivity even to light received from the back surface or other surfaces. An example of the present invention is shown in FIGS. 4 and 6.

A plastic-molded PIN photodiode 13, which is an infrared receiving element, and components constituting an amplifier 4, which is a peripheral circuit shown in FIG. 3, are attached to the printed circuit board 11 at the same time. In the illustrated example, the light receiving element 13 is mounted approximately at the center of the printed circuit board 11, and the components constituting the amplifier 4 are mounted around it. As a result, a larger area is required for the printed circuit board 11, which is the light receiving element mounting portion, than when only the light receiving element 13 is attached. In this example, this wide mounting area is effectively utilized.

Then, the back side of the printed circuit board 11 (which is the light receiving element mounting part)
The entire pattern surface) is covered with a metal case 12. On the other hand, covering the surface of the printed circuit board 11 (component mounting surface), which is the light-receiving element mounting portion, with the metal case 12 is avoided as much as possible.

Therefore, care must be taken to avoid interference from other circuits.

However, interference from the back side of the printed circuit board 11 can be shielded by the metal case 12.

In the illustrated example, the printed circuit board 11 is attached to the metal case 12 by inserting a plurality of protrusions 17 integrally provided on the metal case 12 into the holes 1S of the printed circuit board 11 and then soldering them.

In FIG. 4, light rays 14, 15, and 16 incident at the same angle as the conventional aperture angle θ directly enter the light receiving element 13. Also light 1
5, the light 15' incident at an incident angle θ passes through the printed circuit board 11, which is the mounting part for the light receiving element r, is reflected by the metal case 12, passes through the printed circuit board 11, which is the element mounting part 11, again, and
The light is incident on the back surface of the light receiving element 13. 15, 1 at incident angle θ
Some of the light other than 5' also reaches the light receiving element 13 due to diffuse reflection.
Enter.

In this way, stronger infrared rays than before can be received, extending the reach. Moreover, it goes without saying that when the surface side of the light-receiving element r13 is covered less or not tψ, the angle of incidence θ becomes wider, which is effective in extending the reach.

As described above, according to the present invention, reflection from surrounding objects,
By making the infrared rays incident at a narrow angle further reflected by the metal case and making the infrared rays incident from the back surface of the light-receiving element, the reachable distance of the infrared rays can be extended. The present invention increases the reach distance by 10% compared to the conventional example.
The result was that it was extended by ~20%.

[Brief explanation of the drawing]

1 and 2 are perspective views and sectional views showing the configuration of a conventional light receiving device, FIG. 3 is a block diagram of the same light receiving device, and FIG. 4 is a sectional view of a light receiving device according to an embodiment of the present invention. , FIG. 6 is an exploded perspective view of the same device. 11... Light receiving element mounting portion, 12... Metal case, 13... Light receiving element. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 3

Claims (1)

[Claims] The infrared receiving element is mounted parallel to the element mounting part on the surface of this mounting part, the back side of the former element mounting part is completely covered with a metal case, the front side is open, and there is no space around the element mounting part. A light receiving device that uses a printed circuit board containing circuit components.