JPH0643691Y2 - Optical encoder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an optical encoder using a light emitting element having a lens barrel and a lens.

[Prior art]

In a conventional optical encoder, a light emitting diode (hereinafter referred to as LE
In general, as shown in FIG. 3, an encoder disk 5 provided with a disk pattern formed of optical slits such as a large number of light-transmitting parts (not shown) is provided on the rotating shaft 10 as shown in FIG. Fixed, the light emitting side circuit board 13 having the LED light emitting element 11 and the circuit components 12 fixed thereon is arranged on one side of the encoder disk 5, and the light receiving side circuit board 7 having the light receiving element 6 fixed thereon is arranged on the other side. Was there. When a general LED light emitting element is used for the above optical encoder, it is necessary to put a plurality of LED light emitting elements 15 with lenses 14 in a holder 16 to form an assembly in order to prevent oblique light of the LED light emitting element. It was

However, the disadvantages of the LED light-emitting element 15 with a lens are that the cost is high and oblique light cannot be prevented.

As another general method, there is a method of using the LED light emitting element 3 in which the lens barrel portion 17 and the aspherical lens 18 shown in FIGS. 5 and 6 are combined.

When the lens barrel 17 and the aspherical lens 18 are combined,
The light emitted from the light emitting element chip 3a of the LED light emitting element 3 passes through the aspherical lens 18 and reaches the light receiving element 6,
b, c, and turbulent rays d, d ', e, e', etc. which reach the light receiving element 6 after passing through the lens barrel 17, and the turbulent rays d, d ',
There is a drawback that e, e ', etc. adversely affect the encoder output signal generated from the original parallel light a, b, c, and the scattered light emitted from the peripheral portion adversely affects the encoder characteristics.

Also, in order to block the above-mentioned irregular light, conventionally, the lens barrel portion 17 is painted,
It had a cover etc.

[Purpose of device]

In view of the above drawbacks, the present invention has changed the shape of the lens barrel holding the aspherical lens in the LED light emitting element having the aspherical lens so that the light receiving element of the encoder is less likely to be irradiated with irregular light, thereby eliminating unnecessary light. The purpose of the present invention is to propose an optical encoder that eliminates the adverse effects of irradiation and improves the characteristics of the output signal of the encoder.

[Constitution of device]

The present invention relates to an optical encoder in which an encoder disk having an optical slit is arranged between a light emitting element and a light receiving element, in which a lens barrel part and a lens part are integrally formed of a translucent material, The inclined surface portion is provided on the inner peripheral side of the tip of the lens barrel portion surrounding the lens portion.

〔Example〕

The present invention will be described below with reference to the illustrated embodiments. The light emitting element 3 used in the optical encoder of the present invention is, as shown in FIG.
A lens barrel portion 1 and an aspherical lens portion 2 are formed of a glass or synthetic resin lens material. An LED light emitting element chip 3a is provided in the lens barrel portion 1 and a lid 4 is attached thereto. An optical encoder is configured by arranging a circuit board 7 provided with a light receiving element 6 with an encoder disk 5 provided with an optical slit (light-transmitting slit) (not shown) at a position facing the lens unit 2.

The lens barrel portion 1 holds the lens portion 2 and protects the lens portion 2.

The encoder disk 5 is fixed and rotated on a rotating shaft (not shown).

A sloping surface portion 8 is formed on the inner peripheral side of the lens barrel portion 1 surrounding the lens portion 2 so as to widen toward the end.

By devising the shape of the lens barrel 1 as described above, LE
Light emitted from the chip 3a in the D light emitting element, passing through the aspherical lens portion 2 and reaching the light receiving element 6 is parallel light a, b, c.
The light d, d ′, etc. reflected by the lens barrel portion 1 is reflected again by the slope portion 8 and goes out to the periphery of the lens barrel portion 1, and the light passing through the lens barrel portion 1 reaches the light receiving element 6 extremely. It will be difficult.

When the light emitting element of the optical encoder is configured to have the inclined surface portion 8 as described above, the light d reflected by the lens barrel portion 1,
The d'and the like are reflected again by the inclined surface portion 8 and go out to the periphery of the lens barrel portion 1, and the lights d, d'and the like passing through the lens barrel portion 1 are extremely difficult to reach the light receiving element 6 and reach the light receiving element 6. The converted light becomes parallel light a, b, c that has passed through the aspherical lens portion 2, and the encoder output characteristics are significantly improved.

Further, it is not necessary to coat the lens barrel portion 1 with a coating or the like for blocking irregular light.

FIG. 2 shows another embodiment. The lens barrel portion 1 has a sloped portion 8 and a flat portion 9 formed on the end face.

Of course, the flat portion 9 is formed so that the light receiving element 6 is not irradiated with light even if the flat portion 9 emits light.

As described above, the tip end of the lens barrel 1 does not necessarily have to be an edge, but may be formed in a cut shape only in a range that does not adversely affect the light receiving element 6, and the slope 8 may be a curved surface.

If the optical encoder is configured as shown in FIG. 2, the distance between the lens barrel portion 1 and the encoder disk 5 can be shortened.

[Effect of device]

Since the present invention is configured as described above, the light or the like reflected by the lens barrel portion is reflected again by the inclined surface portion and goes out to the periphery of the lens barrel portion, and the light or the like passing through the lens barrel portion is extremely transmitted to the light receiving element. Since it is difficult to reach the optical encoder, it is possible to provide an optical encoder that exhibits practically excellent effects such that the encoder output characteristics produced by parallel light are significantly improved.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention. FIG. 1 is a sectional side view of an essential part of an optical encoder, FIG. 2 is a sectional side view of an essential part of another embodiment of the optical encoder, and FIG. FIG. 4 is a side view of the structure of a conventional encoder, FIG. 4 and FIG. 5 are side views of the structure of a conventional light emitting element, and FIG. DESCRIPTION OF SYMBOLS 1 ... Lens barrel part, 2 ... Lens part, 3 ... LED light emitting element, 5 ... Encoder disk, 6 ... Light receiving element, 8 ... Slope surface part.

Claims (1)

[Scope of utility model registration request] 1. An optical encoder in which an encoder disk having an optical slit is arranged between a light emitting element and a light receiving element in which a lens barrel portion and a lens portion are integrally formed of a light transmitting material. An optical encoder characterized in that an inclined surface portion is provided on an inner peripheral side of a front end of the lens barrel portion surrounding the lens portion.