JPH0211793Y2 - - Google Patents

Description

[Detailed explanation of the invention] A. Industrial application field This invention arranges a light-emitting element and a light-receiving element in parallel,
The present invention relates to a reflective optical coupler that uses a light receiving element to detect reflected light from a light emitting element.

B. Prior art A conventional reflective optical coupler, as shown in Figure 1,
Although the light-emitting element 11 and the light-receiving element 12 were held in parallel in the same housing 17, the light detection sensitivity was not sufficient, and the amount of light detected changed due to, for example, blurring when the reflector moved. . In order to correct this, it is common to increase the amount of light emitted, but this is not desirable because it requires a large capacity power supply, shortens the life of the element, or requires an expensive optical coupler.

C. Purpose of the invention This invention provides a constant output even if the amount of light emitted is the same, even when the object to be detected such as a reflector vibrates, as long as the position of the object to be detected is within a predetermined range. In other words, it provides a reflective optical coupler with sufficiently high detection sensitivity.

D. Structure of the invention In the present invention, since the optical surfaces of the conventional elements 11 and 12 are flat, the entry and exit of light depends only on the refractive index, and the spread of the light is determined by the position of the optical surface and the semiconductor inside it. This was done in consideration of the fact that there is a limit to the size of such reflective optical couplers, and that there is no positional margin in the distance relationship between the optical surface and the semiconductor inside it. The optical surface has streak-like unevenness. The present invention will be described in detail below based on examples.

E. Embodiment Figure 2 is a perspective view of a reflective optical coupler according to an embodiment of the present invention, using as an example a tape end detection sensor that inserts the tip into a small window of a cassette tape half and detects light reflection on the magnetic surface of the tape. It's getting better. 1, 2 in the figure
are a light emitting element and a light receiving element molded with resin, respectively. This is the lead wire 3 as shown in Figure 3.
An optical semiconductor 4 such as a light emitting diode or a photodiode supported by a light emitting diode or a photodiode is molded with a resin 5 such as an epoxy resin, and an optical surface 6 through which light is led out or introduced is provided with streak-like unevenness 6'. Reference numeral 7 denotes a frame body that encloses and holds both elements 1 and 2 in a parallel arrangement, and has a through hole 8 for attachment and corner portions 9, 9, . . . that serve as tape guides. The rectangular parts 9, 9... are for guiding the tape from the upper and lower surfaces, but the corners are made of a pair of rectangular parallelepipeds placed on the upper and lower surfaces of the tape, so that the tape contact surface is flat, and the tape is If the tape is guided, the tape may shift when the capstan is close, causing problems such as the tape edges breaking, so it is more preferable to guide the tape at two points separated from each other in the running direction.
They are provided at the four corners of the frame 7.

In the above-mentioned structure, the light spreads in a direction substantially perpendicular to the stripes due to the stripes 6'. This is equivalent to arranging a large number of columnar lenses with various focal points. The spread of light is approximately 5 to 20 degrees wider than when the optical surface is flat. (The degree of spread is related to the size and density of the unevenness.) Unlike when using a single lens, this spread of light is close to scattering, so the amount of light detected by the light receiving element is reduced by the blurring of the tape (reflector). It doesn't change much. This effect is particularly great when the stripes are provided in the same direction as the arrangement direction of both elements 1 and 2. If the stripes are provided in a direction substantially perpendicular to the arrangement direction, the amount of light dissipated increases and the influence of external light increases. Since it is easily affected, it may be used for purposes other than detecting the tape end (for example, detecting curled portions of paper (reflector) in a copying machine).

F. Effect of the invention As described above, the present invention provides a reflective optical coupler in which a resin-molded light-emitting element and a resin-molded light-receiving element are arranged in parallel. Because it is a thing,
Excellent detection sensitivity for blurring on reflective surfaces.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a conventional optical coupler, FIG. 2 is a perspective view of a reflective optical coupler according to an embodiment of the present invention, and FIG. 3 is a perspective view of a light emitting or light receiving element used therein. DESCRIPTION OF SYMBOLS 1... Light emitting element, 2... Light receiving element, 3... Lead wire, 4... Optical semiconductor, 5... Resin, 6... Optical surface, 6'... Unevenness, 7... Frame, 8... Through hole, 9,
9... Corner.

Claims (1)

[Scope of utility model registration request] In a reflective optical coupler in which a resin-molded light-emitting element and a resin-molded light-receiving element are arranged in parallel, a plurality of streak-like irregularities are formed on the optical surface of each molded resin so that both elements are approximately parallel to each other. A reflective optical coupler characterized by the following: