JPH1062205A - Rotary slit plate and rotation-detecting apparatus using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate a strict positional detection using a fixed slit, by providing a slit pattern asymmetric to a rotational direction. SOLUTION: The light from a light-emitting diode passes through a disk- shaped rotary slit part 2 fitted perpendicularly to a shaft (drive shaft) and enters a photosensor. A waveform of the light is shaped to rectangular. The rotary slit part 2 is provided with a slit 10 which forms a certain fixed pattern, namely, a slit pattern whereby output pulses are different between rotational directional CW and CCW and which is not uniform in length (Breadth) in a circumferential direction. The shaped rectangular pulses show different waveforms in the rotational directions CW and CCW. In consequence, a fixed slit is not used and a strict positional detection is eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a rotating slit plate and a rotation detecting device using the same, and more particularly to a rotating slit plate for a shaft encoder and a rotation detecting device using the same.

[0002]

2. Description of the Related Art When it is necessary to detect the rotation direction of a shaft by a rotation detector for a shaft encoder, conventionally, as shown in FIG. The light passes through a disk-shaped rotary slit portion 2 vertically attached to the shaft and a fixed slit portion 2-1 fixed and arranged to face the rotary slit portion 2,
The signals are detected (converted into electric signals) by the photosensors 3-1 and 3-1 and subjected to waveform shaping (4-1 and 4-2) to form two A-phase and B-phase rectangular wave pulses.

As shown in FIG. 4B, these two rectangular wave pulses are out of phase by 90.degree. In phase A as compared to phase B, for example, when the shaft is rotating clockwise (CW). In phase A, when the phase A is advanced and the shaft is rotating counterclockwise, the phase A is delayed.

[0004] Rotating slit section 2 and fixed slit section 2-1
For example, as shown in FIG. 6A, a light shielding slit is formed in a glass disk by a photo process (a silver photosensitive agent is applied and exposed using a mask). The light-shielding slit is a black (for example, silver oxide) band radially arranged at equal intervals from the center of the disk, and the fixed slit portion 2-1 has a smaller A than the B ′ portion as shown in FIG. 6B. In the 'part, the arrangement of the bands is 90 ° out of phase.

When there are two light emitting diodes 1, the two light emitting diodes 1 and the photosensors 3-1 and 3-1 are connected as shown in FIG.
It is made to face the A 'part and the B' part of (b). When one light emitting diode 1 is provided, the light emitting diode 1 is provided at the connection portion between the A ′ portion and the B ′ portion in FIG.
Are provided in the A ′ section and the B ′ section close to.

Rotating slit section 2 and fixed slit section 2-1
Since the light-shielding band of and the transmission part between them are almost the same width,
The A-phase and B-phase pulse waveforms whose waveforms have been shaped (4-1, 2) are substantially symmetric rectangular waves. The phase of A phase and B phase is 9
It shifts by 0 ゜. As shown in FIG. 5, the A-phase rectangular wave pulse is bisected, one through the gate 31 and the other through the gate 32.
And 33, the capacitor C
, C2 and registers R1 and R2, and gate 34
And 35, two pulses of opposite phase are derived.

When these two pulses of opposite phase and the rectangular pulse of phase B are gated by NAND gates 36 and 37, a down pulse and an up pulse are derived. When the down pulse and the up pulse are applied to a flip-flop composed of NAND gates 38 and 39, NAN
The rotation direction of the shaft (for example, "1" for CW, "0" for CCW) can be detected as the output of the D gate 39.

Further, the down pulse and the up pulse are set to NA
When mixed by the ND gate 40, a pulse output indicating the rotational phase of the shaft is obtained.

[0009]

In the case of the shaft encoder shown in FIG. 4A, extremely accurate shaft position detection can be obtained, but it is difficult to adjust the mounting accuracy of the fixed slit and the rotating slit. It is inevitable that it will be expensive.

On the other hand, in the case of a rotary encoder directly connected to a cable drum of a device for feeding and winding a cable or the like using hydraulic pressure or the like as a drive source, not so severe position detection is required.

An object of the present invention is to provide a rotary slit plate for a rotary encoder that does not require strict position detection and a rotation detecting device using the same.

[0012]

According to the present invention, there is provided an encoder for detecting rotation by receiving light transmitted through a slit provided in a disk-shaped rotating plate by a light receiving element and converting the light into a pulse signal. A slit plate having a slit pattern that is asymmetric with respect to the rotation direction is obtained.

[0013] The slit pattern is characterized in that it is an array pattern of a plurality of slits whose width changes sequentially along the circumferential direction.

According to the present invention, the above-mentioned slit plate, a light emitting and receiving element provided with the slit plate interposed therebetween,
Means for detecting rotation in accordance with the output from the light receiving element.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of a rotational position detecting device according to the present invention, and the same parts as those in FIG. 4 are denoted by the same reference numerals. In addition, overlapping description is omitted.

In FIG. 1 (a), light emitted from a light emitting diode 1 passes through a disk-shaped rotating slit portion 2 vertically mounted on a shaft (drum shaft), enters a photosensor 3, and has a waveform. It is shaped (4) into a rectangular waveform.

As shown in FIG. 2, the rotary slit portion 2 has:
By forming a slit pattern in which output pulse widths are different from each other in a predetermined pattern, that is, in the CW direction and the CCW direction, the waveform is shaped by providing slits 10 that are not equal in length (width) in the circumferential direction. The rectangular pulse has a waveform as shown in FIG. In this case, different waveforms are obtained depending on CW and CCW in the rotation direction of the rotation slit section 2.

The pulse detection circuit shown in FIG.
The clock is counted up by the counter 25 only while the gate is open. The value counted by the counter 25 is input to the output of the gate 21 and the timing generation circuit 24 which operates on the clock, and
When the gate of the D circuit 23 is completed, the data is latched by the latch 26 and the counter 25 is cleared.

In this case, the counter 25, latch 26, C
The wiring connecting the PUs 27 is an n-bit parallel wiring.

The count value of the latched counter 25 is proportional to the circumferential length of the slit 10 provided in the rotary slit section 2, and the CPU 27 causes the CPU 27 to perform normal rotation (CW) / reverse rotation (CW) / counter rotation in the arrangement order of the count value. CCW) can be determined, and the rotation speed can be determined from the count value.

For example, the slit 10 of the rotary slit section 2
Assuming that there are three types of slit lengths and the length ratio is 4: 2: 1, the count value (pattern) in the case of forward rotation (CW)
Is naturally 4: 2: 1. In the case of reverse rotation, a count value (pattern of) of 1: 2: 4 is obtained.
W) / reverse rotation (CCW).

The number of rotations can be recognized by counting the number of appearances of the pattern. Rotation speed is (shaft is 1
r. p. It is obtained by (count number when rotating at m) / (obtained count number).

When four sets of 4: 2: 1 slit patterns are arranged in the rotary slit section 2, the slit lengths are set to 4 mm, 2 mm, and 1 mm, and the interval between the slits 10 is set to 2 mm. The circumferential length of the arrangement position is (4 + 2 + 1) × 4 + 2 × 12 = 40 (mm).

Assuming that the clock frequency is 3,000 Hz, the shaft is driven at 1 r. p. The count number of a 4 mm slot when rotated at m is (4/40) × 60 (s) ×
3,000 = 18,000.

At this time, the obtained count value is 1,800.
Is 18,000 / 1,800 = 10
(Rpm), and a rotation speed can be obtained. If the clock frequency is set sufficiently high, the rotation speed can be detected with high accuracy.

[0027]

As described above, the present invention has an effect that an economical rotary encoder can be obtained without using a fixed slit.

[Brief description of the drawings]

FIG. 1A is a block diagram of an embodiment of the present invention, and FIG.
FIG. 4 is an operation waveform diagram thereof.

FIG. 2 is a plan view of a rotary slit section of the present invention.

FIG. 3 is a diagram illustrating an example of a pulse detection circuit that processes the output pulse of FIG. 1;

FIG. 4A is a block diagram of a conventional rotary encoder, and FIG. 4B is a diagram illustrating an example of an output pulse thereof.

FIG. 5 is a diagram illustrating an example of a pulse detection circuit that processes the output pulse of FIG. 4;

FIG. 6 is a plan view of a conventional rotating slit and a fixed slit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light-emitting diode 2 Rotation slit part 3 Photosensor 4 Waveform shaping 21 and 22 Gate 23 AND gate 24 Timing generation circuit 25 Counter 26 Latch 27 CPU

Claims (3)

[Claims] 1. A slit plate of an encoder for detecting rotation by receiving light transmitted through a slit provided on a disk-shaped rotating plate by a light receiving element and converting the light into a pulse signal, wherein the slit plate is provided in the rotation direction. A slit plate having a slit pattern that is asymmetrical to the slit plate. 2. The slit plate according to claim 1, wherein the slit pattern is an array pattern of a plurality of slits whose width sequentially changes along a circumferential direction. 3. The slit plate according to claim 1 or 2,
A rotation detecting device comprising: a light emitting and light receiving element provided with the slit plate interposed therebetween; and means for detecting rotation according to an output from the light receiving element.