JPH0422262Y2 - - Google Patents

Description

[Detailed description of the invention] a. Industrial application field The present invention relates to a rotary encoder, particularly an optical type, to improve the level of the output signal at the zero position and to obtain a stable zero position signal. It concerns new improvements for.

b. Prior Art Various configurations have been proposed and adopted for this type of optical rotary encoder that has been used in the past, but representative configurations are shown in Figures 3 and 4. As shown in the figure.

That is, in the configuration shown in FIG. 3, one first slit 3 and one second slit 4 are formed in the rotating disk 1 and the fixed plate 2, respectively, and the two slits are formed on both sides of the rotating disk 1 and the fixed plate 2. A light emitting element 5 and a light receiving element 6 are arranged.

Further, in the configuration shown in FIG. 4, a plurality of first slits 3 and a plurality of second slits 4 are formed in the rotating disk 1 and the fixed plate 2, respectively, and a plurality of first slits 3 and a plurality of second slits 4 are formed on both sides of the rotating disk 1 and the fixed plate 2. Although a light emitting element and a light receiving element are arranged in the same way as in FIG. 3, they are omitted in FIG. 4. Further, each of these slits 3 and 4 is formed accurately in the radial direction from the rotation center O.

The conventional optical rotary encoder is configured as described above, and its operation will be explained below.

In the case of Fig. 3, the rotating shaft 1a is rotated by the required angle,
When the optical axes of the first slit 3 of the rotating disk 1 and the second slit 4 of the fixed plate 2 coincide, the light from the light emitting element 5 passes through each slit 3 and 4 and enters the light receiving element 6, and 1 zero position is detected.

In addition, in the case of Fig. 4, a plurality of first slits 3 and a plurality of second slits 4 are formed, and the optical axes of each slit 3 and 4 coincide with each other, and the case where one slit coincides with each other. The zero position of the rotating disk 1 is detected based on the output difference.

c. Problems to be solved by the invention Since the conventional rotary encoder is configured as described above, the following problems existed.

First, in the case of the conventional configuration shown in Figure 3, which is used in an encoder with relatively low pulses (for example, 100 pulses/rotation), the zero position signal with a relatively wide width W produces a stable output as shown in Figure 5. However, in encoders with high pulses (for example, 5000 pulses/rotation), a zero position signal with a narrower angular width is desired.

However, considering the output waveform when the angular width W is 1/4 of that in the configuration shown in Fig. 3, the width of the slit through which the light passes is 1/4, so the width W of the output voltage from the light receiving element is , as shown in Figure 6, 1/4W
The peak voltage value was also 1/4H. Therefore, in the zero position signal having the waveform shown in FIG. 6, the ON/OFF signal processing was unstable compared to the reference voltage.

The conventional configuration shown in FIG. 4 was used as an improved version of the conventional configuration shown in FIG. 3, but if the slit width was the same as the waveform shown in FIG. As shown, the peak value of the output voltage when light passes through one slit is 1/4H,
When passing through four slits at the same time, the output will be H, but if each slit faces in the radial direction and the rotating disk rotates at high speed, zero level detection will be impossible due to the characteristics of the light receiving element. Therefore, it is difficult to reduce the amount of light passing through at least one slit or less, and as shown in the waveform diagram shown in Fig. 7, the peak value 1 due to one slit as described above is It was difficult to obtain a highly sensitive zero position signal by lowering /4H.

The object of the present invention is to promptly eliminate the above-mentioned problems and to obtain a rotary encoder that can obtain a highly sensitive zero position signal suitable for high-speed rotational encoders.

d. Means for Solving the Problems The rotary encoder according to the present invention includes a rotating disk having a plurality of first slits, a fixed plate having a plurality of second slits, and a state in which the rotating disk and the fixed plate are sandwiched. The device includes a light-emitting element and a light-receiving element, and the longitudinal direction of each slit is deviated from the radiation direction passing through the center of rotation.

e Effect In the rotary encoder according to the present invention,
Since the longitudinal direction of each slit formed in the rotating disk and the fixed plate are all deviated from the radial direction passing through the center of rotation, the optical axes of all the slits coincide at the zero position and all the first and second slits are aligned. The light can pass through the first slit and the second slit at other than the zero position.
The slits do not have their longitudinal directions completely aligned, but their longitudinal directions intersect with each other to form a dot shape, so the amount of light passing through each slit can be smaller than the amount of light that passes through one conventional slit, increasing sensitivity. A good and stable zero position signal can be obtained.

f Embodiments Hereinafter, preferred embodiments of the rotary encoder according to the present invention will be described in detail with reference to the drawings.

Note that the same or equivalent parts as in the conventional example will be described using the same reference numerals.

1 and 2, a plurality of first slits 3 and a plurality of second slits 4 are formed in the rotating disk 1 and the fixed plate 2, respectively, and on both sides of the rotating disk 1 and the fixed plate 2, A light emitting element 5 and a light receiving element 6 are provided.

The above-mentioned first slit 3 and second slit 4 are
They are constructed as shown in FIG. 2, and both have radial directions P ₁ ,
P ₂ , −P ₁ and −P ₂ (indicated by dashed lines) are formed at angles shifted from each other. That is,
The longitudinal directions Q ₁ , Q ₂ , −Q ₁ and −Q ₂ in which each first slit 3 and each second slit 4 are formed (indicated by two-dot chain lines) and the aforementioned radial directions P ₁ , P ₂ , − P ₁ and −
Angular differences -θ ₁ , -θ ₂ , θ ₁ and θ ₂ are formed between the slits 3 and ₄ in the rotating disk 1 and the fixed plate _{2 .} , θ ₁ and θ ₂ are all formed at exactly the same angle.

The rotary encoder according to the present invention is constructed as described above, and its operation will be described below.

The zero position of the rotating disk 1 is detected when the rotating disk 1a is rotated and the optical axes (namely, hole positions) of the slits 3 and 4 all coincide.

Furthermore, at positions other than the zero position of the rotating disk 1, the first slit 3 and the second slit 4 are in a point-shaped state in which not a single slit coincides in the radial direction, and all of them intersect in the non-radial direction. Since they only intersect in the radial direction, the area of intersection is smaller than before, and the amount of light that passes through the intersecting state is equal to that of the conventional state in which one slit in the radial direction arranged in the radial direction in Fig. 4 intersects. The amount of light is much smaller than the amount of light, which is a fraction of the amount of light, and the difference between the amount of light passing at the zero position and the amount of light passing at a non-zero position is greatly clarified to detect the zero position. It becomes possible to obtain high sensitivity.

Note that the shape of the slit in this embodiment is merely an example, and the same effects can be obtained not only in this embodiment but also when using slits in other shapes.

g Effects of the invention Since the rotary encoder according to the invention has the above-described configuration and function, compared to the conventional configuration, the slits are positioned in the non-radial direction, so that the rotary encoder according to the invention has the structure and function as described above. Compared to the above, the amount of light passing through at a non-zero position can be made extremely small, thereby greatly increasing the sensitivity of the zero position signal when detecting the zero position, and making it possible to obtain a stable and highly accurate zero position signal. Detection can be performed.

[Brief explanation of drawings]

1 and 2 are for showing the rotary encoder according to the present invention. FIG. 1 is a block diagram showing the overall structure of the main parts, FIG. 2 is a block diagram showing the overall structure, and FIG. Figure 4 shows a conventional configuration, Figure 3 is a schematic perspective view showing the overall configuration, and Figure 4 shows a conventional configuration.
This figure is a block diagram of the main part showing another conventional example, FIGS. 5 to 7 are waveform diagrams showing conventional signals, and FIG. 8 is a waveform diagram of signals in the present invention. 1 is a rotating disk, 2 is a fixed plate, 3 is a first slit, 4 is a second slit, 5 is a light emitting element, and 6 is a light receiving element.

Claims (1)

[Claims for Utility Model Registration] (1) Rotating disk 1 having a plurality of first slits 3
and a fixing plate 2 having a plurality of second slits 4.
and a light emitting element 5 and a light receiving element 6 arranged with the rotating disk 1 and the fixed plate 2 sandwiched therebetween,
In a rotary encoder that generates a zero position signal only at the zero position, the longitudinal direction _Q1 to _Q2 of each of the slits 3 and 4 is formed at an angle deviated from the radial direction _P1 to _P2 passing through the center of rotation. A rotary encoder characterized by having a configuration. (2) The rotary encoder according to claim 1, wherein each of the slits 3 and 4 is composed of four slits.