JPH08166257A - Rotary encoder and rotary disk used in this rotary encoder - Google Patents

Abstract

PURPOSE: To provide a rotary encoder for highly accurately detecting the rotation angle and rotation direction of a rotary shaft with a very simple structure. CONSTITUTION: A rotary disk 10 is provided with a digital track 1 constituted of a plurality of slits and an analog track 3 with its light transmission coefficient gradually changed, the light quantity of light passing through the analog track 3 is detected by a photodiode 5b, converted into a digital value by an A/D converter 6 and based on this digitized output signal, the absolute rotary angle of the rotary disk 10 is calculated. A plurality of digitized light quantities are compared by a rotary direction detection part 7 and the increase/decrease thereof is detected and the rotation direction of the rotary disk 10 is calculated. On the other hand, a pulse passing through the digital track 1 is detected by a phototransistor 5a and the relative rotation angle of the rotary disk 10 is calculated based on its pulse number and information on the rotation direction of the rotary disk 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary encoder for detecting or controlling the position of a rotary shaft by outputting a digital signal corresponding to the rotational position of the rotary shaft in conjunction with the movement of a motor. The present invention relates to a rotary disk used for an encoder.

[0002]

2. Description of the Related Art Conventional rotary encoders include an analog angle encoder using a potentiometer and a digital rotary encoder including a rotating disk, an LED, a phototransistor and the like. However, the analog angle encoder has a problem that the position detection accuracy is poor, a large torque is required to rotate the potentiometer, and a poor contact is likely to occur in the potentiometer. Therefore, recently, digital rotary encoders with low torque and high position detection accuracy have been widely used. There are roughly two types of rotary encoders, an absolute encoder that detects the absolute position of the rotary shaft and an incremental encoder that detects the relative position of the rotary shaft.

[0003]

Among them, the absolute encoder has a high position detection accuracy, but has a drawback that the hardware configuration for it is large, and the incremental encoder has an absolute position detection of the rotating shaft. In addition, a photo-slit having a phase difference of 90 ° and a complicated detection circuit are required to detect the rotation direction.

[0004] In addition, an incremental slit for high-speed rotation and an absolute pattern code for low-speed rotation are provided in the circumferential direction of the rotary disk, so that an accurate rotation angle of the rotary disk according to high-speed and low-speed can be determined. Although what is required has been proposed (JP-A-63-99620),
In order to detect the rotation direction, a complicated detection circuit, a complicated pattern code and a plurality of detection devices for reading the same are still required.

Further, Japanese Laid-Open Patent Publication No. 2-161312 discloses a semi-transmissive portion provided on a rotating disk for use in detecting a predetermined position. However, since this apparatus detects the rotational direction. Requires a circuit configuration for detecting a plurality of photo interrupters and their phase differences.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned conventional drawbacks, and has a very simple structure and can accurately detect an absolute rotation angle, a relative rotation angle, and a rotation direction of a motor or the like with high accuracy. The purpose is to provide.

[0007]

In order to achieve the above object, a rotary encoder according to the present invention comprises a digital track having a plurality of slits and an analog track whose light transmittance changes gradually along a circumferential direction. It comprises a disk, a light emitting means for giving light to the digital track and the analog track, a pulse detecting means for detecting a pulse passing through the digital track, and a light amount detecting means for detecting a light amount of the light passing through the analog track. It is as a configuration.

Further, according to the present invention, the absolute rotation angle calculating means for calculating the absolute rotation angle of the rotating disk from the light quantity detected by the light quantity detecting means is compared with a plurality of continuously detected light quantities for rotation. A rotation direction detecting means for determining a rotation direction of the disk; and a relative rotation angle calculating means for calculating a relative rotation angle of the rotating disk from the number of pulses detected by the pulse detecting means and the output of the rotation direction detecting means. It is also possible to add and configure.

Further, according to the present invention, there is provided a rotating disk provided with a digital track formed of a plurality of slits and an analog track whose light transmittance changes gradually along the circumferential direction.
Light emitting means for giving light to the digital track and the analog track, a light receiving element for detecting a pulse passing through the digital track, a light receiving element for detecting a light amount of light passing through the analog track, and a light passing through the analog track An A / D converter for digitizing the light quantity of light, a rotation direction detecting means for determining a rotation direction from a digitized light quantity signal, the number of pulses passing through the digital track, and an output of the rotation direction detecting means. And a relative rotation angle calculating means for calculating the relative rotation angle of the rotating disk.

In this case, the rotating disk is formed by stacking a digital disk having a plurality of slits in the circumferential direction with a digital track and an analog disk having a circumferential direction in which the analog track whose light transmittance changes gradually. It can also be configured.

[0011]

In the above arrangement, the amount of light passing through the analog track is detected by the light amount detecting means.
It is digitally converted by a D converter. Since the detected light amount has a constant value than the absolute rotation angle of the rotary disc, the absolute rotation angle of the rotary disc is calculated from the digitized output signal. Further, a plurality of digitized light amounts are compared to detect an increase or decrease, and the rotation direction of the rotating disk is calculated. On the other hand, the pulse passing through the digital track is detected by the pulse detecting means, and the relative rotation angle of the rotating disk is calculated from the number of pulses and information on the rotating direction of the rotating disk.

[0012]

The present invention will be described below with reference to the drawings. FIG. 1 is a schematic explanatory view of a rotary encoder showing an embodiment of the present invention, and FIG. 2 is a plan view of a rotary disk in FIG. In this embodiment, the rotary disk 10 of the rotary encoder is formed by superimposing a digital disk 10a and an analog disk 10b. The digital disk 10a has a digital track 1 and an auxiliary digital track 2, and the analog disk 10b has an analog track. 3 are respectively formed along the circumferential direction.

The digital track 1 on the digital disk 10a is provided with a large number of slits for each minimum detection angle according to the angle detection accuracy of the target encoder.
The rotation angle is measured by detecting the passage / non-passage of light by the slit.

The analog track 3 on the analog disk 10b is a track whose light transmittance is gradually changed along the circumferential direction. It is configured to change to the lowest transmittance. The analog track 3 may be formed by embedding a light-transmitting plate whose light transmittance changes gradually in an analog disk, or by coating a light-shielding coating film on a transparent analog disk. . Further, an analog track can be formed so that the light transmittance is changed from the highest to the lowest in one round or a half round.

The auxiliary digital track 2 is for indicating the discontinuous area of the analog track 3, and the output of this track is used as an auxiliary signal for detecting the rotation direction. Note that the disk surface of the analog disk 10b corresponding to the digital track 1 and the auxiliary digital track 2 and the disk surface of the digital disk 10a corresponding to the analog track 3 cover the entire track so as not to hinder signal detection by them. A slit is provided.

For the digital track 1, the analog track 3 and the auxiliary digital track 2, the LEDs 4,
4 and phototransistors 5 and 5 respectively face from both sides. The LEDs 4 and 4 are light-emitting means that emit light by being supplied with power from the LED power supply 4a. When light is emitted to the digital track 1 during rotation of the disk, the light repeatedly passes / non-passes by the slit, and the disk rotation speed A pulse having a frequency corresponding to is formed. Also,
When the light emission is performed on the analog track 3, the light reduced in accordance with the light transmittance at the irradiation position is transmitted.

Illuminated by LEDs 4 and 4, digital track 1, analog track 3 and auxiliary digital track 2
Are respectively detected by the phototransistor 5. The pulse of the digital track 1 detected by the phototransistor 5a is output to the up / down counter 9 and the number of pulses is counted. The light amount of the light that has passed through the analog track 3 and detected by the phototransistor 5b is output to the A / D converter 6 and converted into a digital signal.

The amount of light digitally converted by the A / D converter 6 is output to an absolute rotation angle calculation unit (not shown) for calculating the absolute rotation angle of the rotary disk 10 and the rotational direction of the rotary disk 10 is calculated. Rotation direction detector 7
Is output to The absolute rotation angle calculation unit calculates the absolute rotation angle of the rotating disk based on the detected light amount. The rotation direction detection unit 7 compares a plurality of digitized light amounts, detects the increase or decrease, and calculates the rotation direction of the rotating disk. In this case, a plurality of light amounts are detected based on the timing signal of the timing signal generator 8 and compared.

The up / down counter 9 is supplied with a signal indicating the rotating direction from the rotating direction detecting section 7, and gives information on the rotating direction to the number of pulses generated by the digital track 1 to rotate it. Calculate the relative rotation angle of the disc.

Next, the operation of the present invention will be described with reference to this embodiment. In the above configuration, the amount of light passing through the analog track 3 of the rotating rotating disk 10 is detected by the phototransistor 5b, and is converted into a digital signal by the A / D converter 6. Since the detected light amount has a constant value than the absolute rotation angle of the rotary disc, the absolute rotation angle of the rotary disc is calculated from the digitized output signal.

Further, the rotation direction detecting section compares a plurality of digitized light amounts to detect the increase / decrease, and the rotation direction of the rotary disk 10 is calculated. In this case, the discontinuous portion of the light transmittance of the analog track 3 is detected by the auxiliary digital track 2 so that there is no erroneous detection when detecting the light amount.

On the other hand, the pulse passing through the digital track 1 is detected by the phototransistor 5a, and the up / down counter 9 calculates the relative rotation angle of the rotating disk from the information on the number of pulses and the rotating direction of the rotating disk. It Further, the angular velocity of the rotary disk 10 can be calculated based on the number of pulses per unit time.

Although the present invention has been described with reference to the preferred embodiments, the present invention is not necessarily limited to the above embodiments, and various improvements and modifications can be made based on the claims. For example, in the embodiments, the rotating disk is constituted by a digital disk and an analog disk. However, it is of course possible to form a digital track and an analog track on a single disk to carry out the present invention.

[0024]

As described above, according to the present invention, by providing both the analog track and the digital track on the rotary disk of the rotary encoder, the conventional absolute type and increment type encoders have a very simple circuit configuration. It is also possible to have the functions of (1) and (2), which has the effect of being able to detect the absolute position and rotation direction of the rotating shaft with high accuracy.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view showing one embodiment of a rotary encoder according to the present invention.

FIG. 2 is a plan view of a rotary disk used in an embodiment of the rotary encoder of the present invention.

[Explanation of symbols]

 1 Digital Track 2 Auxiliary Digital Track 3 Analog Track 4 LED 4a LED Power Supply 5 Phototransistor 6 A / D Converter 7 Rotation Direction Detector 8 Timing Signal Generator 9 Up / Down Counter 10 Rotating Disc 10a Analog Disc 10b Digital Disc

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display area G01D 5/36 F

Claims (5)

[Claims] 1. A rotating disk having a digital track formed of a plurality of slits and an analog track whose light transmittance changes gradually along a circumferential direction, and a light emitting means for giving light to the digital track and the analog track. A rotary encoder comprising: pulse detecting means for detecting a pulse passing through the digital track; and light amount detecting means for detecting a light amount of light passing through the analog track. 2. A rotating disk having a digital track formed of a plurality of slits and an analog track whose light transmittance changes gradually along a circumferential direction, and a light emitting means for giving light to the digital track and the analog track. A pulse detecting means for detecting a pulse passing through the digital track, a light amount detecting means for detecting a light amount of light passing through the analog track, and an absolute rotation angle of the rotating disk from the light amount detected by the light amount detecting means. Absolute rotation angle calculating means for calculating, rotation direction detecting means for determining the rotation direction of the rotating disk by comparing a plurality of light amounts continuously detected, the number of pulses detected by the pulse detecting means, and the rotation Relative rotation angle calculation means for calculating the relative rotation angle of the rotating disk from the output of the direction detection means, Rotary encoder according to claim. 3. A rotating disk having a digital track formed of a plurality of slits and an analog track whose light transmittance changes gradually along a circumferential direction, and a light emitting means for giving light to the digital track and the analog track. A light receiving element for detecting a pulse passing through the digital track, a light receiving element for detecting a light quantity of light passing through the analog track, an A / D converter for digitizing a light quantity of light passing through the analog track, and a digital Relative rotation angle calculating means for determining the rotation direction from the converted light amount signal, the number of pulses passing through the digital track, and the output of the rotation direction detection means for calculating the relative rotation angle of the rotating disk. A rotary encoder comprising a calculating means and. 4. A rotary disk of a rotary encoder, comprising a digital track formed of a plurality of slits and an analog track whose light transmittance gradually changes along the circumferential direction of the rotary disk. 5. The rotating disk is formed by stacking a digital disk having a digital track formed of a plurality of slits in the circumferential direction and an analog disk having an analog track having a gradually changing light transmittance in the circumferential direction. The rotary disk of the rotary encoder according to claim 4, wherein