JPH10221120A - Optical encoder apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical encoder apparatus which completely prevents light as a noise from entering a light-receiving element, whose S/N is high and whose reliability is high. SOLUTION: An encoder apparatus is provided with a moving slit 1 in which first slits 11 are formed, with a fixed slit 2 which is arranged, via a gap, between a light source 4 used to radiate diffusion light and the moving slit 1 and which is composed of second slits 21 fulfilling the role of light-source slits and that of idex slits and of a plurality of third slits 22 in which the phase of slit pitches is deviated from each other by 90 deg.C and with light-receiving elements 3 by which reflected light from the first slits on the moving slit 1 is detected via the third slits 22 on the fixed slit 2 in such a way that the diffusion light radiated from the light source 4 is transmitted through the second slits 21 on the fixed slit 2 so as to irradiate the moving slit 1. The relative displacement and the angle of both the moving alit and the fixed slit are detected on the basis of a cyclic change in output detection signals of the light- receiving elements 3. In this case, a light isolating body 6 is installed around the second slits 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical encoder device.

[0002]

2. Description of the Related Art As a conventional example, Japanese Utility Model Laid-Open No. 2-67219 is disclosed. This is a configuration as shown in FIG. 4 in order to almost completely block noise light and obtain a signal having a sufficiently high SN ratio. Hereinafter, this conventional example will be briefly described. 4, while the first grating 11 of pitch P ₁ that is fixed to one of the members relative movement between glass main scale 100 as a first scale reflective formed on the side surface top of the Figure, the relative movement A light source 4 that emits illumination light that is not converted into parallel rays,
A part of the illumination light from the light source 4 is blocked and the first grating 1
The second grating 21 of pitch P ₂ for illuminating a 1 and the second
And the second grating 21 for further limiting the illumination light limited by the first gratings 21 and 11 and the third grating 22 having a pitch P ₃ independent of both sides of the upper surface so as to sandwich the second grating 21. Second scale 2 made of glass formed on
00 and a light receiving element 3 for detecting the illumination light limited by the first to third gratings 11, 21, and 22. In this configuration, the second and third
The gratings 21 and 22 are used as the light source 4 and the light receiving element 3
An optical insulator 6 formed on the side surface and intercepting light from directions other than the second scale 2 is provided between the light source 4 and the light receiving element 3 and around the light receiving element 3. The surfaces of the two scales 2 on which the second and third gratings 21 and 22 are formed are brought into close contact with each other. The optical insulator 6 is made of, for example, rubber, and a gap between the optical insulator 6 and the second scale 2 is, for example, 0.2 mm or less. The second grating 21 and the third grating 22
As shown in detail in FIG. 5, a second grating 21 having a pitch P ₂ for forming a plurality of line light sources is provided on the second scale 2.
Center is formed in a circular, for dividing the direction discrimination and electrically detecting signals on both sides, the pitch P ₃ of the A + phase whose phases are shifted by 90 degrees from each other, B + phase, A- phase, B-
Four third gratings 22a to 22d of the phase were formed in a rectangular shape, and the optical insulator 6 was formed around the light source and the light receiving element as shown in the figure.

[0003]

The light source 4 as in the conventional example
And the light-receiving element 3 are arranged on the same surface side in a reflection type configuration,
Most of the noise light is light that is emitted from the light source and reflected by the second scale 200 and reaches the light receiving element. In the conventional example, since the optical scale is provided around the light source and the light receiving element and the second scale 200 is attached, a gap is easily opened between the second scale 200 and the optical insulator 6, and the light emitted from the light source 4 becomes the second scale. There is a problem that light serving as noise reflected by the scale 200 leaks into the light receiving element and the S / N ratio is deteriorated. Therefore, an object of the present invention is to provide an optical encoder device that completely prevents light that becomes noise from entering a light receiving element and has a high S / N ratio and high reliability.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is directed to a moving slit in which a first slit having a plurality of grids is formed in a moving direction and fixed to one member which moves relatively. And a second slit, which is fixed to the other member that moves relatively and is disposed via a gap between the light source that emits diffused light and the moving slit, and serves as a light source slit and an index slit, respectively. And a diffused light emitted from the light source passes through a second slit on the fixed slit, irradiates the movable slit, and illuminates the movable slit. A light receiving element for detecting reflected light from the first slit above via a third slit on the fixed slit, and periodically detecting a detection signal output from the light receiving element. In optical encoder so as to detect the relative displacement and the angle of the two members from the variation, it is provided with a light insulator around the second slit. Further, an optical insulator is provided around the second slit and at least one or more of the third slits. Further, the optical insulator is formed by etching, sputtering or vapor deposition.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of Embodiment 1 of the present invention. In the figure, 1 is a moving slit, 2 is a fixed slit,
Reference numeral 3 denotes a light receiving element, 4 denotes a diffusion light source, 5 denotes a substrate on which the light receiving element is mounted, and 6 denotes an optical insulator. A first slit is formed on the moving slit 1 by depositing chromium, aluminum, or the like. On the fixed slit 2, a second slit 21 forming a line light source array and a third slit 22 serving as an index slit which causes a change in the amount of light related to the relative movement amount are formed by chromium vapor deposition or the like. The third slits 22 are slits 22a, 22b, 22c whose slit pitch phases are shifted by 90 degrees from each other.
22d. The light receiving element 3 is formed of a chip component such as a photodiode chip, is disposed on a substrate having a wiring pattern formed of a material such as epoxy resin, and outputs a signal to the substrate 5 with a copper wire 31. It has a configuration. The light beam 41 emitted from the diffusion light source 4 is the second
The light is transmitted through the slit 21, reflected by the first slit 11 on the movable slit 1, transmitted through the third slit 22 on the fixed slit 2, and is incident on the light receiving element 3. In order to prevent the light beam 41 emitted from the light source 4 from being reflected by the second scale 2 and reaching the light receiving element, the optical insulator 6 is provided with an adhesive material so as not to cover the second and third slits around the second slit. It is attached to the fixed slit by the above method. The material of the optical insulator 6 may be any material that does not transmit light, and is made of a material such as plastic, resin, or rubber.

FIG. 2 is a sectional view taken along line AA in FIG. In the figure, 22a is an A + phase slit (third slit), 22b is a B + phase slit (third slit), 22
c is an A-phase slit (third slit), 22d is a B-phase slit (third slit), 23a is an origin phase slit (Z +), and 23b is an origin phase slit (Z-) formed on the fixed slit 2. ing. The optical insulator 6 is attached around the second slit 21 in close contact with the slit deposition side of the fixed slit 2. When the number of the third slits 22 and the number of the corresponding light receiving elements 3 are large, the method of attaching the optical insulator only around the second slits is very simple. Next, a second embodiment will be described.
FIG. 3 shows the second slit 21 and the third slits 22a and 22b.
Example 2 in which an optical insulator 6 is provided is shown. In the drawings, the same names are denoted by the same reference numerals, and redundant description is omitted. this is,
For example, when a light beam transmitted through the A + phase slit 22a reaches the B− phase slit 22d, this light becomes noise in the B− phase. In order to avoid such a situation, the optical insulator 6 is brought into close contact with the fixed slit not only around the second slit but also around the third slit. The optical insulator 6 may be provided on at least one of the third slits. The optical insulator 6 can be formed not only by an adhesive or the like but also by a chemical treatment such as etching, sputtering, or vapor deposition. The material of the moving slit 1 and the fixed slit 2 is not limited to glass, but may be metal or the like. In the above embodiment, a linear encoder,
Obviously, it is applicable to both rotary encoders.

[0007]

As described above, according to the present invention, since no gap is formed between the fixed slit 2 and the optical insulator 6, the light rays 41 emitted from the light source 4 are reflected by the second scale 2 and received. Since the S / N ratio does not reach the element, a highly reliable optical encoder device can be provided.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a first embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA in FIG.

FIG. 3 is a configuration diagram showing a second embodiment of the present invention.

FIG. 4 is a configuration diagram of a conventional example.

FIG. 5 is a diagram showing an arrangement of second and third slits in a conventional example.

[Explanation of symbols]

 Reference Signs List 1 moving slit 11 first slit 2 fixed slit 21 second slit 22 third slit 22a A + phase slit 22b B + phase slit 22c A-phase slit 22d B-phase slit 23a origin phase slit (Z +) 23b origin phase slit (Z- 3) light receiving element 31 copper wire 4 diffused light source 41 light beam 5 substrate 6 optical insulator 100 main scale 200 second scale

Continuation of front page (72) Inventor Koji Nakajima 2-1 Kurosaki Castle Stone, Yawatanishi-ku, Kitakyushu-city, Fukuoka Prefecture Inside Yaskawa Electric Corporation

Claims (3)

[Claims] 1. A moving slit in which a first slit having a plurality of lattices in a moving direction is fixed to one relatively moving member, and a diffused light fixed to the other relatively moving member. A second slit, which is disposed with a gap between a light source for emitting light and a moving slit and serves as a light source slit and an index slit, respectively, and a plurality of third slits in which the phase of the slit pitch is shifted by 90 degrees from each other. A slit, diffused light emitted from the light source passes through a second slit on the fixed slit, irradiates the moving slit,
A light receiving element for detecting reflected light from a first slit on the moving slit via a third slit on the fixed slit; An optical encoder configured to detect a target displacement and an angle, wherein an optical insulator is provided around the second slit. 2. The optical encoder device according to claim 1, wherein an optical insulator is provided around said second slit and at least one of said third slits. 3. The optical encoder device according to claim 1, wherein the optical insulator is formed by etching, sputtering, or vapor deposition.