JPH0425616Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] This invention is a structure of an optical rotary encoder used as a sensor for detecting mechanical movement and displacement in NC machine tools, etc. and converting it into an electrical signal. It is related to.

[Conventional technology and its problems]

A conventional general optical rotary encoder has a light emitting element 10 such as an LED as shown in FIG.
It is composed of a combination of a fixed code plate 20, a rotating code plate 30, and a light receiving element 40. The rotation code plate 30 is formed by forming a large number of radial transparent slits arranged at equal intervals in the circumferential direction by depositing an opaque material such as chrome on a transparent thin disk such as glass. be. Similarly, in the fixed code plate 20, slit groups of A phase and B phase are formed in a fan shape.

A phase difference of 90° is required between the A-phase and B-phase output signals as shown in FIG. For this reason, the A-phase slits and the B-phase slits in the fixed code plate 20 are shifted in position from each other in advance by a phase of 90°, that is, by 1/2 the pitch of the slits in the rotating code plate 30. When the fixed code plate 20 is installed at the correct position and the A-phase and B-phase optical paths are aligned with predetermined positions, a 90° phase difference is generated in the output signal.

However, in order to extract outputs with an accurate 90° phase difference between A and B phases, it is necessary to use the fixed code plate 2.
0 and the rotation code plate 30 must be precisely positioned relative to each other. However, as the number of slits increases and the signal density increases, it becomes increasingly difficult to adjust the position of the fixed code plate 20.

[Purpose of invention]

The present invention aims to reduce the number of man-hours required for assembling a rotary encoder by providing a configuration in which the phases of A phase and B phase can be easily adjusted.

[Means for solving problems]

This invention uses a semiconductor laser as a light source,
It is characterized by a structure in which a lens holder is rotatably mounted between the semiconductor laser and the rotary code plate, and a lens is eccentrically mounted to the lens holder.

That is, in the present invention, by rotating the lens holder, the optical path of the light irradiating the slit is bent by an eccentric lens, and the phase can be adjusted.

〔Example〕

FIG. 1 shows an embodiment of the present invention.
In this figure as well, parts corresponding to those in FIGS. 3 and 4 are designated by the same reference numerals, and redundant explanations will be omitted.

50 is a board fixed to the main body of the rotary encoder. A semiconductor laser 60 for the A phase and a semiconductor laser 60 for the B phase are respectively attached to the two holes 52 for light passage formed in the substrate 50. These two A-phase and B-phase semiconductor lasers 60 face a slit provided on the same circumference of the rotation code plate 30. The two semiconductor lasers 60 may be placed at any position facing the slit of the rotation code plate 30. A female thread is cut inside the hole 52, and a substantially cylindrical lens holder 70 is attached to this female thread.
are screwed together. A lens 80 is fixed inside the lens holder 70, and the lens 80 is slightly shifted from the center line 54 of the hole 52 and eccentric.

The light beam from the semiconductor laser 60 passes through the lens 80 and is then irradiated onto the slit surface of the rotary code plate 30, whereupon it is received by the light receiving element 40. However, the lens 80 is decentered and the lens holder 70
Therefore, at different rotational positions of the lens holder 70, the optical path of the light 90 from the semiconductor laser 60 is bent in different directions as shown in FIG. That is, by rotating the lens holder 70, the optical path can be moved within a certain range of the slit surface of the rotary code plate 30. In order to create an accurate 90° phase difference between the A-phase and B-phase output signals, the A-phase optical path, the B-phase optical path, or both optical paths are slightly shifted along the circumferential direction of the rotary code plate 30. All you have to do is move it. Therefore, by rotating the lens holder 70, the phases of the A phase and B phase can be adjusted. This phase adjustment work is preferably performed while observing the output waveform with an oscilloscope, and after the adjustment is completed, the lens holder 70 is preferably fixed to the substrate 50 with adhesive.

When the width of the slit becomes about several microns, the influence of dirt and dust adhering to the slit surface increases. The light from the semiconductor laser 60 is focused by a lens 80 and irradiated onto the slit surface of the rotary code plate 30, but the position of the lens 80 is adjusted so that the focus of the light is shifted to the front or back of the slit surface. By making the luminous flux on the slit surface approximately the same size as the width of the slit, noise caused by dust can be reduced. In addition, the rotation code plate 30
If the slit surface is sandwiched between slightly thick glass plates on both sides, dust will adhere to the surface of the glass plate away from the slit surface, so the focus should be adjusted so that the light beam on the glass surface becomes wider. By adjusting this, the generation of noise can be further suppressed.

Note that a collimator lens may be added between the semiconductor laser 60 and the lens 80 if necessary.

[Effect of idea]

According to the present invention, phase matching can be easily performed by rotating the lens holder while looking at the output waveform. Therefore, not only productivity is improved, but even if a phase shift occurs after long-term use, the phase can be easily corrected.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a part of the main part of a rotary encoder according to an embodiment of the present invention, FIG. 2 is an explanatory diagram showing changes in the optical path when the lens holder is rotated, and FIG. A schematic configuration diagram of the rotary encoder, and FIG. 4 is an output waveform diagram. 30... Rotation code plate, 40... Light receiving element, 50
... Substrate, 52 ... Hole, 60 ... Semiconductor laser,
54... Center line, 70... Lens holder, 80
……lens.

Claims (1)

[Scope of utility model registration request] a semiconductor laser fixed to a substrate having a hole for light passage; a rotary code plate having a plurality of slits formed along the circumference; a light receiving element that receives the light of the semiconductor laser transmitted through the slits; In a rotary encoder equipped with a lens located between a semiconductor laser and a rotary code plate, and a lens holder holding the lens, the lens holder is rotatably attached to a hole in a substrate, and the lens is decentered from the center line of the hole. A rotary encoder characterized by being fixed to a lens holder.