JPH0210113A - Optical system encoder using optical fiber - Google Patents

Abstract

PURPOSE:To improve the utilization efficiency of light by guiding light from an LED only to an opening slits group on a fixed board arranged to the pattern of a rotary slit through an optical fiber and irradiating a photodetector with said light. CONSTITUTION:The laser light from the LED 8 is guided to an optical fiber tow 7 fixed on the optical fiber fixed board 6. The light is distributed to plural distributional fibers 71 with the optical fiber tow 7 and the arrangement pattern of the distributional fiber 71 is made to coincide with an opening slit 62 out of a spacer 61 and the opening slit 62 formed on the rotary slit 4. The emissive light from the distributional fiber 71 passes only through the opening slit 62 of the rotary slit 4 and irradiates the photodetector 5. Thus, the utilization efficiency of the LED light can be improved and power consumption can be saved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical encoder used for positioning a servo motor or a machine tool.

[Conventional technology]

Conventionally, as shown in FIGS. 5A and 5B, for example, LED
(Light-emitting diode) Fixing the luminous flux R from 8 through slit 6'
Of the light transmitting part 62' and the light blocking part 61' arranged over a fixed length with a width W' on the fixed slit 6', only the light passing through the transmitting part 62' is transmitted to the lower rotating slit 4. The light-receiving element 5 received the light through the brightness and darkness.

[Problem to be solved by the invention]

Due to its structure, LEDs have a perfectly circular light beam in cross section (R in Figure 5B).
), but as shown in Figure 5B, the only light energy that is effectively utilized is the amount β1 that is irradiated onto the light transmitting portion 62' of the fixed slit, and the amount β1 that is irradiated onto the light blocking portion 61' of the slit. The light energy of β3 and the parts β2 on both sides outside the slit are not used, and the unused amount (β2+β
3) is much larger than the usage amount (!1).

Therefore, this wasted amount is large, so in order to ensure a sufficient amount of light reaching the light receiving element, a large current must be applied to the LED.
Therefore, the current consumption was large.

The present invention prevents the occurrence of unused amount of optical energy (β2+β3) in the above-mentioned conventional optical encoder,
The purpose is to reduce the power consumption of LEDs.

[Means and effects for solving the problem] For example, as shown in FIG. 3C, the fixed slit part in the optical fiber fixing table has a width W that matches the pattern of the rotating slit, and the slit of the rotating slit is fixed at a certain length. A spacer 61 as a light blocking part and an opening slit 62 as a light transmitting part are arranged in accordance with the shape, and the distribution fiber 71 at the distal end of the optical fiber tow 7 is stuffed into the opening slit 62, and the distal end of the optical fiber tow 7 is packed in the opening slit 62. were fixed opposite to the light emitting part of the LED.

Therefore, all of the light from the LED is guided through the optical fiber and is irradiated onto the rotating slit only from one end of the distribution fiber.
There was no dissipation of the amount of light to 2+A, ), and all the light emitted energy from the LED could be used.

〔Example〕

FIG. 3A to FIG. 3E are explanatory diagrams of an optical fiber fixing base, and the fixing slit portion of the fixing base is a rotating slit.
It has a width W that matches the width of the slit part (Fig. 1 4),
The length in the circumferential direction is 8+nm, and the width T of the spacer 61 is 5.
The width S of the 0p1 open loss slit 62 was closed to 507 - (therefore, there were 80 open slits in the L ellipse), the slit form was made to match the pattern of the rotating slit, and one side of the open slit was made open O.

The optical fiber uses a tow consisting of about 4,800 filaments, and the base end is fastened with a band to form a fixed part 72.
The tip portion is distributed and stuffed into each opening slit 62 separated by a spacer 61 within the length L of the fixed slit portion as a distributed fiber, and then opened with a well-known solvent-based adhesive. It flowed in from the side and solidified. After the adhesive 63 has solidified, the distribution fiber distal end face F1 and the fiber tow proximal end face F2 are polished, the adhesive is applied onto the fixing part 72 on the outer periphery of the toe proximal end, and the fixing part 72 is fixed in front of the LED 8 in the fixing base 6. The optical fiber fixing base was fitted into the fitting recess C of the part, and an optical fiber fixing stand as shown in FIG. 3E was completed.

The assembly of the optical encoder consists of a shaft 3 supported by a flange 1 via a bearing 2, as shown in FIG. 4A.
The disk of the rotary slit 4 is fitted onto the top, and the rotary slit 4 is fixed with an adhesive 41 to a center runout of 4 nodes or less, and then the light receiving element 5 is attached to the light receiving element fixing base 51 as shown in FIG. 4B. After completing the positioning of the light receiving element 5 and the rotating slit 4, the light receiving element fixing base 51 was screwed to the flange 1.

Next, as shown in FIG. 4C, the pre-assembled optical fiber fixing base 6 (see FIG. 3E) was positioned and screwed onto the light receiving element fixing base 51 using a spigot means.

Finally, as shown in FIG. 4D, the printed board 9 was attached to the flange 1, and the LED was also soldered to the printed board.

In the obtained encoder, although the number of optical fibers packed into each aperture slit was not necessarily constant, there was no problem with the detection sensitivity of the light receiving element.

When assembling the optical fiber fixing table, the tip of the optical fiber tow is separated and a separate slit body is distributed and fixed, and only one piece of the optical fiber is assembled in advance, and then the slit body and the slit body at the tip are assembled in advance. It is also possible to adopt a method of fitting and fixing the base end fixing part to the optical fiber fixing stand.

[Effects of the Invention] The amount of light from the LED is guided by the optical fiber, and the light emitting distribution fiber of the optical fiber is distributed among the aperture slit groups of the fixed base in a state that matches the pattern of the rotating slits. The irradiation loss of unusable light such as β3 to the light blocking portion in FIG. 5B and 12 other than the slit portion in FIG. 5B can be completely eliminated, and the power consumption of the LED can be reduced to less than half of the conventional one.

[Brief explanation of the drawing]

FIG. 1 is a schematic side view of the encoder of the present invention, and FIG. 2 is a schematic plan view of the encoder of FIG. 1 with the printed board removed. FIG. 3A is a plan view of the fixing part of the optical fiber tow,
FIG. 3B is a side view of the same. Fig. 3C is an explanatory diagram of a state in which the distribution fiber is packed into the slit, Fig. 3D is a schematic side view of the state in which the distribution fiber is completely packed into the slit, and Fig. 3E is a completed state of the optical fiber fixing stand. It is a schematic side view. FIGS. 4A to 4D are diagrams showing the assembly steps of the pulse coder of the present invention, respectively. FIG. 5A is a schematic side view of a conventional example, and FIG. 5B is a plan view for explaining its operation. ■...Flange, 2...Bearing, 3...
...Shaft, 4...Rotating slit, 5...
・Light receiving element, 6... Optical fiber fixing stand, 7.
...Optical fiber tow, LED, 9-...Printed board, 51
... Light receiving element fixing base, 61 ... Spacer, 62 ... Slit, 63
...Adhesive, 71...Distribution optical fiber 7
2...Fixed part. -N Nog Ln-■Sahe■■ Ln C+-

Claims (1)

[Claims] 1. The light from the LED (8) is transmitted through the opening slit (62) of the fixed base (6) arranged in accordance with the pattern of the rotating slit.
) An optical encoder using an optical fiber, characterized in that the light is guided only into the group via an optical fiber (7), and the light emitted from the tip of the optical fiber illuminates a rotating slit and is transmitted to a light receiving element. 2. The opening slit (62) is an open (0) slit on one side formed between each spacer (61) of the fixing base (6), and the optical fiber (7) is connected to the slit (62) group.
2. The optical encoder according to claim 1, wherein the opening (0) is closed with a split distribution fiber (71) packed at the tip of the optical encoder. 3. The base end of the optical fiber (7) is fastened with the fixing part 72 and fixed opposite to the light emitting part of the LED, and the tip of the optical fiber (7) is distributed and fixed within the opening slit group of the fixing table as a distribution fiber (71). The optical encoder according to claim 1.