JPH0424512A - Encoder - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an encoder having a pattern of a circuit 1 corresponding to a read signal and second and third patterns for forming the read timing signal.

2. Description of the Related Art This type of encoder has a plate-shaped body such as a disk or a long plate with a means for changing the amount of light such as a slit or a reflective mark.
It is well known to form a band-like pattern consisting of a mark array using a capacitance changing means such as a gap change or a magnetic changing means, and convert the pattern into an electric signal using a sensor. In particular, in the case of an encoder used when reading a desired read signal such as an absolute pattern shaped into a single track as serial data, the read signal must be read separately from the pattern; It is known that there are two separate patterns: a repeating pattern and an inverted pattern.

FIG. 3 shows an example of such a known encoder.A long plate-like body 10 has a read signal and a first pattern 11 consisting of an absolute pattern formed by changing the width of slit rows, for example, and The second pattern 12 is a repeating pattern at every tth equal pitch to form a read signal.
A third pattern 13, which is a B rotation pattern of the second pattern, is formed, and each light receiving sensor (not shown) of one sensor body 20 is arranged to face each of the patterns 11 to 13.

In the above, when a relative movement occurs between the plate-like body 10 and the sensor body 20, the first sensor of the sensor body 20 receives an absolute signal in contrast to the first pattern, and also the second pattern.
, the third sensor generates triangular wave-like outputs having an inverse relationship to each other, such as S1□ and S13 shown by solid lines and broken lines in FIG. 4, respectively, corresponding to the second and third patterns. That is, the output of S11 (not shown) becomes H (either H or L may be used) depending on the width of the slit corresponding to the absolute pattern, and near the tip and rear end of the slit, the output is opposite to the sensor due to the opposing position. Since the area changes, the output gradually increases from L to H and gradually decreases from H to L, respectively.S1□ periodically repeats H and L with a row of slits at an equal pitch, but as in S11 above, the output increases gradually from L to H, and gradually decreases from H to L. At the rear end, the output gradually increases and decreases, resulting in an approximately triangular wave-like output, and S II exceeds S 12, resulting in an output that is the inversion of H. The read timing signal is this 312, S
Based on I3, for example, rjL is formed by a differential amplifier, and Sl. The timing signal T shown in FIG. 4 is output while S13 is greater than S13. For example, by reading the output of SII at the falling edge of T, the fourth
The read signal M shown in the figure is obtained.

Note that the output S12 for forming the timing signal T is
, S l) has a triangular wave shape as a result of the opposing area between the mark and sensor at the end of the mark increasing and decreasing linearly.
Depending on the state of change of the facing area, the shape becomes a sine wave or a trapezoid, but even in this case, the read timing signal formed from them is the same.
, this is a case where the third pattern is formed on the plate-shaped body 10 with a 180 degree shift, but the same is true even if the patterns are in the same phase and the second and third sensor positions are shifted by 172 of the pattern pitch. By arranging the positions where the second pattern and the sensor face each other and the third pattern and the sensor at positions opposite to each other, the relative positions are shifted by 180 degrees, thereby obtaining outputs that are inverted from each other.

Problems to be Solved by the Invention By the way, in order to enable the desired reading as described above, the plate-shaped body 10 and the sensor body 20 must be placed in a predetermined positional relationship (in the example of FIG. 3, the first to third sensors It is necessary to assemble and adjust them so that they are arranged on a line perpendicular to the moving direction of the plate-like body 10.

That is, for example, if the sensor body 20 is shifted counterclockwise by θ with respect to the plate-shaped body 10 as shown by the dashed line in FIG. 3, then S', 2, S'0 . As shown in , the outputs of the second and third sensors are in phase with respect to the outputs S12 and S13 when they are in the correct positional relationship, and the outputs of S'12 and S' are The amount of phase progression is different from each other.

As a result, the read timing signal is also T for T.
’. At this time, the output S' of the first sensor (not shown) does not remain at S11, but changes in phase, but the amount of change in phase is not the same as the amount of change in phase of read timing signal T'. In the end, the read signal is read at a different timing,
There is a risk of incorrect output being retrieved.

For this reason, accurate assembly and adjustment of the encoder requires a great deal of time, and a decline in manufacturing efficiency is unavoidable.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides a first pattern in which mark rows are formed in correspondence with desired read signals;
The second mark consists of repeating mark rows formed at equal pitches.
, a third pattern are provided in parallel on the plate-like body, and the first pattern is
, the first and second patterns arranged opposite to the second and third patterns.
, a first output corresponding to the first pattern from the third sensor, an @2 output corresponding to the second pattern, and a third output corresponding to the third pattern and having an inverse relationship with the above @2 output. In the encoder, the outputs are taken out respectively, and the first output is read by a read timing signal formed based on the second and third outputs. They are arranged in parallel at symmetrical positions across the pattern.

When a relative movement occurs between the plate-shaped body and the sensor body, the first to third sensors of the sensor body receive first to third outputs corresponding to the first to third patterns, respectively. is generated, a read timing signal is formed from the second and third outputs, and the first output is read based on the read timing signal. However, if an out-of-area occurs between the plate-shaped body and the sensor body, if the first pattern is used as a reference, the second and third patterns
As a result, the pattern of t! is in a symmetrical position across it. J
Regarding the relative positional deviations between the J2 pattern and its sensor, and the third pattern and its sensor, the absolute amount of deviation is the same and the direction of deviation is opposite.

Therefore, the second and third outputs have the same absolute value of the phase shift, and if one is advanced, the other is delayed, and the differential output is formed based on the second and third outputs. In other words, the phase of the read timing signal remains the same as in the state with no slope.

Embodiment In FIG. 1, a first pattern 11 consisting of an absolute pattern formed by changing the width of a slit row, which serves as a read signal, is arranged in the center of a long plate-like body 100 along the longitudinal direction. 3rd and 2nd patterns 13.12, which are repeating patterns at equal pitches and their inverted patterns, are arranged at symmetrical positions below and above (direction orthogonal to the longitudinal direction) across the Each light receiving sensor (not shown) of the sensor body 200 is arranged to face each other.

In the above configuration, when a relative movement occurs between the plate-shaped body 100 and the sensor body 20, the second and third sensors output the same outputs as in FIG. 4, that is, the same symbols S17 and S1 in FIG.
An output indicated by 1 is generated, thereby forming a read timing signal T in the same manner as described above, and based on the read timing signal T, a read signal corresponding to the first pattern 11 (not shown) is read.

The above is a state in which the positional relationship between the plate-like body 100 and the sensor body 200 is accurately adjusted, but now consider the case where the sensor body 200 is assembled with an angle of θ with respect to the plate-like body 100. , if we take the position of the first pattern as a reference, @2, which faces the second and third patterns 12 and 13,
The positions of the third sensors are shifted by the same distance to the right and left, respectively. As a result, the outputs of the second and third sensors are those whose phases have advanced by the same amount relative to S12 and S1, respectively, as shown as S'12 and S'1. in FIG. It will be delayed by the same amount.

As is clear from the figure, the read timing signal T'', which is the differential output of S12, S11, is the differential output of S12, S'1. As a result, the phase of the output T is exactly the same as that of the output T when accurate assembly and adjustment has been performed, and the first output S1. The read signal (not shown) is also the same as M in the case where there is no slope.

Effects of the Invention As described above, the present invention arranges the second and third patterns for forming a read timing signal at symmetrical positions sandwiching the first pattern corresponding to the read signal, so that the pattern is not formed easily. The inclination of the plate-shaped body and sensor body does not cause errors in reading the read signal, and assembly and adjustment are extremely simplified, and even if the inclination occurs due to changes over time during use, it does not cause errors. , resulting in an extremely reliable encoder.

4,

[Brief explanation of drawings]

1 and 3 are front views showing an embodiment of the present invention and a conventional technique, respectively, and FIGS. 2 and 4 are explanatory diagrams of the output waveforms of FIGS. 1 and 3, respectively. Plate sensor body first pattern second pattern third pattern

Claims (1)

[Claims] 1. A first pattern formed by forming mark rows corresponding to a desired read signal, and second and third patterns formed by repeating mark rows formed at equal pitches are provided in parallel on a plate-shaped body. , from the first, second, and third sensors arranged opposite to the first, second, and third patterns, respectively.
A first output corresponding to the pattern, a second output corresponding to the second pattern, and a third output corresponding to the third pattern and having an inverse relationship with the second output are respectively taken out, and the second output, In an encoder configured to read the first output based on a read timing signal formed based on the third output, the second and third patterns are arranged in parallel at symmetrical positions with the first pattern in between. An encoder characterized in that it can be arranged.