JP2541171Y2 - Optical encoder - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in the compatibility of an optical encoder having two rows of light-transmitting slits formed in a code plate.

[0002]

2. Description of the Related Art Phase modulation type light for detecting the rotation of a motor
As a scientific encoder, for example, Japanese Patent Publication No. 4-533
There was one described in the report. This is compared with the conventional encoder
I do. Conventional encoders have two rows of translucent slits on the code plate.
Are formed, and the difference in the number of slits
The number of teeth is the same as the number of teeth. Light is transmitted through the transmissive slit
Illuminated and the light passing through the translucent slit is detected for each slit row.
An outgoing photodiode array is arranged. Two
Phase modulation type detection signal from the photodiode array
Is obtained. Conventional encoders have two photodiodes
The phase difference between the detection signals obtained from the
The phase difference between the rotor and stator teeth. For example,
If the phases of the motor rotor and stator teeth match
The detection obtained from two photodiode arrays
The phase difference of the signal becomes zero. Therefore, two photodiodes
Mode based on the phase difference of the detection signal obtained from the
Phase difference between rotor and stator teeth
The timing of commutating the motor coil based on the phase difference
To detect. However, the conventional encoder has the following problems.
Was. Set the motor coil to a constant excitation state and
Detected on the encoder side when the rotation position is fixed
The phase difference should be essentially constant. For example,
Coil so that the phases of the rotor and stator teeth match.
Phase difference detected by the encoder when the
Should be 0. However, the eccentricity error of the code plate,
Due to mechanical errors such as errors in the sensor mounting position
Therefore, even if the coil is kept in a constant excitation state,
The detected phase differences have different values. For this reason,
Each time the encoder is replaced, the phase difference is set in the motor driver.
That the encoder is not compatible
There was a problem.

[0003]

[Problems to be solved by the present invention ]
This was done to solve the problem.
Phase difference between rotor and stator teeth of motor and two rows
And the phase difference between the two detection signals obtained from the light-transmitting slit
Uniquely defining the relationship between
Commutation timing can be detected correctly even if
It is an object of the present invention to realize a certain optical encoder.

[0004]

According to the present invention, a code plate is connected to a motor, and the code plate is formed with two rows of light-transmitting slits.
Is the same as the number of teeth of the motor, and
A light is irradiated to the slits, and a sensor is provided for detecting the light passing through the light-transmitting slit for each slit row, and a motor is provided based on a phase difference between phase modulation detection signals obtained from these two sensors. Phase difference between rotor and stator teeth
An optical encoder that obtains a signal used for commutation control of the motor based on the detected phase difference ,
A phase for shifting the phase and adjusting the phase difference between the two detection signals.
A phase difference adjusting means is provided, and the rotor and stator teeth of the motor are provided.
The phase difference between the two detection signals changes according to the change in the phase difference
And the phase difference adjusting means is
The relationship between the phase difference between the teeth of the
Optical encoder.
You.

[0005]

[0006]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 is a block diagram of one embodiment of the optical encoder according to the present invention. In FIG. 1, 1 is a motor, 2 is a disk-shaped code plate that rotates together with the motor 1, and 3 and 4 are position detection arrays arranged at a constant pitch along the circumferential direction of the code plate 2. The light-transmitting slits 5, 5 are light-transmitting slits formed outside the slits 3 and 4 for detecting the origin, 6 and 7 are LEDs, and 8 and 9 converge the light emitted from the LEDs 6 and 7 to converge the slits 3.
And lenses corresponding to 4,5. Reference numerals 10 and 11 denote photodiode arrays (hereinafter, referred to as PDAs) for detecting light passing through the light-transmitting slits 3 and 4. PDA1
0 and 11 are composed of, for example, eight photodiodes.
The width of the eight photodiodes is the light-transmitting slits 10 and 1
One pitch corresponds to one pitch. Reference numeral 12 denotes a PDA for detecting the origin, which is disposed at the origin of the rotational position and detects light passing through the light transmitting slit 5. 13 and 14 are PDAs 10,
11 is a signal processing circuit for processing the 11 detection signals. In the signal processing circuits 13 and 14, 131 and 141 are PDs.
Switches A10 and 11 provided for each photodiode, 132 and 142 are shift registers for closing the switches 131 and 141 sequentially at the timing of the shift clock and scanning the detection signals of the photodiodes. 1
43 amplifies the scanned detection signal and a step-like waveform signal θ
An amplifier that obtains SG0 and θSG1. 144 is PDA12
This is an amplifier that obtains the origin detection signal from the output of

Reference numeral 15 denotes a phase difference adjusting means which is a feature of the present invention. When the motor 1 coil is kept in a constant excitation state and the rotational position is fixed, waveform signals θSG0 and θSG0 are provided.
This is to make the phase difference of 1 a constant value. FIG. 2 shows a specific configuration example of the phase difference adjusting means 15. In FIG. 2, R is a variable resistor, R 1 and R 2 are resistors, C is a capacitor, U 1
U2 is an amplifier, and JP1 and JP2 are jumper terminals.
In this circuit, the circuit including the amplifier U1 shifts the phase of the signal in the range of -180 ° to 0 ° according to the resistance value of the variable resistor R. The phase shift φ is given by the following equation. φ = −2 arctan ωRC ω: angular velocity, R: resistance value of resistor R, C: capacitance of capacitor C The circuit composed of the amplifier U2 has a signal phase of +180
Shift by °. The phase of the waveform signal θSG0 is shifted to θSG0 ′ by selectively using the circuit composed of the amplifier U1 and the circuit composed of the amplifier U2 in accordance with the phase amount to be shifted.

Returning to FIG. 1, signals 16 and 17 are signals θSG0
', Low-pass filter (hereinafter referred to as LPF) for extracting low frequency components of θSG1, 18 and 19 are comparators for shaping the waveform of the extracted signal, and 20 is for measuring the phase difference between the two waveform- shaped signals. The phase difference counter 21 is a period counter for measuring the period of the signal whose waveform has been shaped by the comparator 19. The commutation angle of the motor is detected based on the value measured by the phase difference counter 20, and commutation control is performed. Further, a variation in the cycle of the detection signal is detected based on the measurement value of the cycle counter 21, and the variation is integrated to determine the rotational position of the motor.

The operation of the optical encoder thus configured will be described. Each of the photodiodes of the PDAs 10 and 11 outputs a current corresponding to the amount of light of the LEDs 6 and 7 received through the light transmitting slits 3 and 4. 3 and 4 show the light transmitting slit 3 and the PDA 10, and the light transmitting slit 4 and the PD.
It is the figure which showed an example of the state which A11 overlapped. The hatched portions in the figure are the light transmitting portions of the light transmitting slit. 1 to 8 are the numbers of the respective photodiodes. The signal processing circuit 13 turns on the switches four by four, and sets a1, a2, a3 in FIG.
As shown in (4), four photodiode outputs are taken out. Since the output taken out is summed by the amplifier 133, the output of the amplifier 133 has a waveform that changes in a stepwise manner according to the extraction timing. Similarly, the signal processing circuit 14 takes out four photodiode outputs as shown by b1, b2 and b3 in FIG. Where b1,
The take-out timings of b 2 and b 3 are a 1, a 2 and a 3
Is synchronized with the extraction timing. With such an encoder, the motor coil is set to a fixed excitation state and
When the rotational position of the motor is fixed, for example, when the rotor is fixed at the rotational position where the phases of the stator and the teeth coincide, the phases of the waveform signals θSG0 and θSG1 should be constant. However, the phase difference Δφ varies as shown in FIG. 5 due to the eccentric error of the code plate, the displacement of the mounting position of the PDA, and the like. The phase difference adjusting means 15 shifts the phase of the waveform signal θSG0 to zero the phase difference Δφ. Here, the phase shift amount is set in the phase difference adjusting means 15 in the following procedure. First, the motor coil is set in a constant excitation state so that the phases of the rotor and the stator teeth coincide with each other. In this state, the phase difference Δφ between the waveform signals θSG0 and θSG1 is measured. As a result of the measurement, if Δφ <0, short JP1; if Δφ ≧ 0, short JP2. Next, θ
The resistance value of the variable resistor R is adjusted so that Δφ = 0 while monitoring the waveforms of SG0 and θSG0 '. All Enco
If such adjustment is made to the motor, the phase difference .DELTA..phi. Becomes zero when the phases of the rotor of the motor and the teeth of the stator match, and the encoder is compatible.

The phase difference adjusting means 15 has a phase difference Δφ
May be adjusted to a value other than 0. That is, the phase difference .DELTA..phi. Adjusted by the phase difference adjusting means 15 is unambiguous with respect to the phase shift .phi.0 generated between the rotor and the stator teeth when the motor coil is set to a constant excitation state. The value itself can be anything if it is determined in advance.

[0011]

[Effects of the Invention] According to the present invention, the phase difference adjusting means
Phase difference between the rotor and stator teeth of the motor and two rows of light transmission
The relationship between the two detection signals obtained from the
It is determined uniquely. For this reason, keep the motor coil constant.
Phase difference obtained on the encoder side when
Becomes constant. For example, the rotor and stator teeth of a motor
When the coil is excited so that the phases of
The phase difference detected on the coder side is zero. Therefore, the sign
Mechanical errors such as plate eccentricity errors and sensor mounting position errors
, Commutation timing can be detected correctly.
This makes the encoder compatible.
The encoder has failed and is replaced with a new one.
It is not necessary to set the phase difference in the driver.
No.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is a diagram showing a specific configuration example of a phase difference adjusting unit .

FIG. 3 is a diagram illustrating the operation of the encoder of FIG. 1;

FIG. 4 is a diagram illustrating the operation of the encoder in FIG. 1;

FIG. 5 is an explanatory diagram of the operation of the encoder of FIG. 1;

 ──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-1-84115 (JP, A) JP-B6-7060 (JP, B2) JP-B4-533 (JP, B2)

Claims (1)

(57) [Scope of request for utility model registration] 1. A code disc have been connected to the motor, the light-transmitting slits in two rows in the code plate have been formed, two rows
The difference between the number of slits of the light transmitting slit is the number of teeth of the motor.
The same number is provided, and light is applied to the light- transmitting slits. Sensors for detecting light passing through the light-transmitting slits are provided for each slit row, and a phase modulation type detection signal obtained from these two sensors is provided. Based on the phase difference, the motor rotor and
In an optical encoder for detecting a phase difference between teeth of a data and obtaining a signal used for commutation control of a motor based on the detected phase difference, a phase of the detection signal is shifted, and a phase of the two detection signals is shifted.
A phase difference adjusting means for adjusting the difference;
The two detections according to the change in the phase difference between
The phase difference of the signal changes, and the phase difference adjusting means
Phase difference between rotor and stator teeth and phase of two detection signals
Optical energy, which uniquely defines the relationship with the difference
Encoder.