JPS6111813Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial application field The present invention relates to a reflective optical coupling device, in particular, which can be installed at a distance of several mm or more from the object to be detected and effectively detect it even if the output of the light emitting element is small. The present invention relates to a reflective optical coupling device.

Reflective optical coupling devices have a simple structure, can be made compact, and can be used in narrow spaces, so they are suitable for use in computer terminals such as card readers, text and graphic reading devices, and motors. It is conveniently used to detect things that change from moment to moment, such as rotation control units of audio equipment and tape recorders, tachometer generators, etc.

Prior Art Such a reflective optical coupling device has, for example, a first
The structure is as shown in the figure. In Fig. 1, 1 is a light emitting element, 2 is a light receiving element, the light emitting element 1 is loaded with light emitting pellets 3 on a pellet loading lead wire 6, and a gold wire (not shown) is connected to an internal wiring lead wire (not shown). )
It is formed by wire bonding. The light-receiving element 2 is similarly formed by stacking light-receiving pellets 4 and wire-bonding them, and the lead wire 6 for pellet loading and the lead wire for internal wiring are made of ceramic or the like of a color that blocks light from the light-emitting element 1. The header 8 is fixed in advance to a header 8 made of aluminum, and the header 8 is formed integrally with the envelope portion 81 and the light-shielding wall portion 82. If the object to be detected is placed in front of the reflective optical coupling device configured in this manner, that is, in the direction in which the light emitting pellet 3 emits light, the light emitted from the light emitting element 1 will be modulated by the object to be detected. The reflected light is received by the light-receiving element 2 and the condition of the object to be detected can be known.

However, in the case where the light emitting element 1 and the light receiving element 2 are arranged almost in parallel as shown in FIG.
A light-emitting element with an output of decreases, making it impractical. In this case, in order to increase the coupling efficiency when the distance between the reflective optical coupler and the object to be detected is short, it is necessary to slightly reduce both the light emitting element 1 and the light receiving element 2, as shown in the cross-sectional view of FIG. If you use one that faces inward, you can align the optical axis close to the reflective optical coupler.
A reflective optical coupling device can be placed close to the object to be detected.

Further, as a device for increasing the coupling efficiency of objects to be detected at a distant location, for example, a reflective optical coupling device as shown in the third example has been considered. That is, in FIG. 3, reference numeral 9 denotes a TO-5 type header, and the light emitting pellets 3 and 4 are loaded on its lead wires and are internally wired. An envelope 12 to which a convex lens 11 is fixed is fixed to the header 9. In this device, since the light emitted from the light emitting pellet 3 is imaged by the convex lens 11, there is an advantage that the resolution can be extremely improved if the image forming position is placed so as to be on the object to be detected. However, this device has the following drawbacks.

That is, first of all, in order to form an image in this manner, the distance between the light emitting pellet 3 and the convex lens 11 must be greater than the focal length of the convex lens 11. However, it is impossible to create a convex lens with a very short focal length, and even with the smallest practical lens, the distance between the light emitting pellet 3 and the convex lens 1 would be 4 to 5 mm, and the reflective optical coupling device itself would have to be large with a total length of 10 mm or more. Become. Further, since the distance between the light emitting pellet 3 and the convex lens 11 becomes longer, the solid angle at which the convex lens 11 is viewed from the light emitting pellet 3 becomes smaller, so that the so-called numerical aperture becomes smaller, and the light coupling efficiency eventually decreases. Second, although there is the advantage of improved resolution through image formation, the image becomes blurry even slightly before and after the image formation position, and the resolution and coupling efficiency drop sharply, so the placement of a reflective optical coupler is not recommended. The drawback is that it is extremely difficult. Furthermore, in manufacturing a reflective optical coupling device, the positions of the light-emitting pellet 3 and the light-receiving pellet 4 are adjusted so that the optical axis from the light-emitting pellet 3 and the optical axis to the light-emitting pellet 4 intersect at the imaging point, or The convex lens must be adjusted by shifting the position, which requires a lot of assembly man-hours, and the distance between the reflective optical coupler and the object to be detected is fixed and has no flexibility, so the range of use is narrow and it is not suitable for mass production. There are drawbacks such as a significant increase in manufacturing costs and inconvenience in use.

Problems that the invention aims to solve However, due to the arrangement of parts, etc., the distance between the reflective optical coupler and the object to be detected can be reduced to 5.
There is a growing demand to increase the output power to mm or more, but in such cases, conventionally the only way was to increase the output of the light emitting element, which required a larger reflective optical coupler and increased power consumption. Although it is inconvenient to use, it has the disadvantage that satisfactory characteristics cannot be obtained.

Means for Solving the Problems In order to solve the above-mentioned drawbacks, the present invention provides an inexpensive and compact reflective optical coupling device that can be used over a wide range even when placed at a distance of 3 mm or more from the object to be detected. Specifically, two astigmatic light condensing parts formed to separately condense light for a light emitting element and a light receiving element for a conventional reflection type optical coupler and mounting A light condensing mechanism integrally formed with a light-emitting element and a light-receiving element is attached so as to be close to the light-emitting element and the light-receiving element.

Effect: According to the reflective optical coupler according to the present invention, the astigmatism focusing mechanism is placed close to the light emitting element and the light receiving element, so that the light emitted from the light emitting element in a 180° direction can be efficiently collected. Furthermore, the light emitted from the focusing mechanism travels with almost the same spot diameter, so even if the distance between the reflective optical coupler and the object to be detected changes slightly, or even at long distances, detection accuracy will not be affected. It can be detected without giving anything.

Embodiment FIG. 4 is a cross-sectional view of a reflective optical coupler according to the present invention, where 13 is a conventional reflective optical coupler part, 14 is a spherical part 141 that collects light separately for the light emitting element and the light receiving element, and the mounting. The spherical part 141 is attached to the envelope of the conventional reflective optical coupler part 13 so that the spherical part 141 is close to the light emitting element 3 and the light receiving element 4, respectively. In this example, the spherical portion 141 is positioned such that the optical axis of the light emitting pellet 3 and the optical axis of the light receiving pellet 4 intersect at the position of the object 15 to be detected. However, as explained earlier, the spherical shape causes astigmatism and does not form an image completely, and only has a focusing mechanism, so the optical path in this case is as shown by the shaded area 16 in Figure 4. Become. In this figure, the optical path is enlarged conceptually, so it appears that the optical path is wide and unsuitable for detection, but the actual size of the reflective optical coupling device is small, less than 5 mm in diameter, and the spot diameter of the optical path is also 1 mm. The front and back are small. Therefore, there is no problem in detecting the end of a tape in a tape recorder or detecting the rotation of a rotating body, and since the spot diameter advances with almost the same size, it is possible to detect objects at long distances. Even if the position of the detector moves slightly back or forth or the surface of the object to be detected and the light emitting/receiving surface are no longer parallel, the coupling efficiency will not drop sharply, and there is no need to be careful about the placement during use. Further, in this example, since the spherical part 141 is used as a light collecting mechanism, this spherical part 141 is used as a light emitting pellet 3.
Moreover, it can be placed close to the light-receiving pellet 4 so as to be almost in contact with it, and the device itself can be made compact.Since the solid angle when viewing the spherical part 141 from the light-emitting pellet 3 is large, the so-called numerical aperture becomes large, and the coupling efficiency of light is improved. This spherical part 141 is the light emitting pellet 3
Since it is sufficient to transmit the light without attenuating it, plastic can be used without using glass or the like, and as in this embodiment, the two spherical parts 141 and the mounting part can be integrally molded from plastic at the same time. and can be easily manufactured. Furthermore, even if this spherical part is not a perfect sphere, it can be a hemisphere, or an ellipse, the same effect can be obtained as long as it is a condensing mechanism with astigmatism that does not focus.

Effects of the invention FIG. 5 shows the characteristics of the reflective optical coupling device according to the invention in comparison with the conventional one. In the figure, the horizontal axis is the distance between the reflective optical coupler and the object to be detected, and the vertical axis is the distance between the reflective optical coupler and the object to be detected, and the vertical axis is the reflected light from the object placed in front when 4mA is applied to the LED on the light emitting element side. There is a method that expresses current in μA. A is the one according to this embodiment shown in FIG. 4, B is the conventional one shown in FIG. 1 without any attachment, and C is the one shown in FIG. 3 using a conventional convex lens. As is clear from the figure, it can be seen that high light coupling efficiency can be obtained over a wide range in this example. Note that the reason that the device according to this example can obtain more output (better coupling efficiency) than the device that focuses using a convex lens is because the light condensing mechanism is placed close to the light emitting element. Seem.

Also, in FIG. 6, the resolution of this type of reflective optical coupler is shown in terms of the spot diameter that hits the object to be detected, as in FIG. That is, the horizontal axis is the same as in FIG. 5, and the vertical axis is the spot diameter in mm. As can be seen from the figure, in the case of this embodiment (A), the spot diameter has almost no effect on the change in distance, whereas in the conventional case (B), where nothing is attached, the spot diameter diverges with distance and as it moves away. The spot diameter becomes larger and larger. In addition, with the conventional lens (C) that uses a convex lens, the spot diameter becomes very small at the focused point, but as the focus shifts, the spot diameter increases rapidly in a parabolic manner, resulting in poor resolution. Recognize. Therefore, if the position of the detected object cannot be adjusted accurately, it is easy to misidentify the detected object, whereas in the embodiment of the present invention, the detected object is located at the front and back (when the reflective optical coupling device is installed). It is possible to perform stable detection with constant resolution regardless of the position (before or after the position).

As mentioned above, the feature of the present invention is that by simply attaching a condensing mechanism to a conventional reflective optical coupling device, the device can be made suitable for detecting objects located at a distance, and as a result, it is inexpensive and reliable. This method has the advantage of providing a device with good performance, improving coupling efficiency over a wide range, enabling accurate detection even at a distance of about 10 mm, and being easy to use and handle. Furthermore, unlike the conventional method, when it is desired to detect an object in a nearby location, it is sufficient to use a device without this condensing mechanism, which has the advantage of wide versatility.

[Brief explanation of the drawing]

Figures 1 and 2 are cross-sectional views of a conventional reflective optical coupler, Figure 3 is a cross-sectional view of a conventional special reflective optical coupler, and Figure 4 is a cross-sectional view of an embodiment of the present invention. 5
The figure shows the relationship between the coupling efficiency of light and the distance between the reflective optical coupler and the object to be detected using the current on the light receiving element side. The conventional one shown in the figure, C is a characteristic diagram of the conventional special one shown in FIG. 3, and FIG. 6 shows the resolution according to the spot diameter in the same way as FIG. 5. 3...Light-emitting pellet, 4...Light-receiving pellet, 1
3... Conventional reflective optical coupler section, 14... Light condensing mechanism, 141... Spherical part.

Claims (1)

[Scope of utility model registration request] It has a light emitting element, a light receiving element, and a light shielding wall and an envelope that prevent light leakage from the light emitting element,
In a reflective optical coupling device in which light emitted from the light emitting element is modulated by the object to be detected and this modulated reflected light is received by the light receiving element, the light emitted from the light emitting element and the object to be detected are A light-emitting element and a light-receiving element are provided with a light-emitting element and a light-receiving element. A reflective optical coupling device, characterized in that it is attached adjacent to the envelope.