JPH09273943A - Multi rotation absolute encoder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect an absolute position at low cost highly accurately, back up for a long time when a main power source is turned OFF and reduce maintenance costs. SOLUTION: The multi rotation absolute encoder is provided with a detecting part 2 which has magnetic sensors 20A, 20B outputting signals corresponding to a revolution number of a body to be detected and operational amplifiers 21A, 21B are outputted signals RA, RB of two phases, a counter part 14 outputting multi rotation signals based on the RA, RB, a backup power source 12 for driving the detecting part 2 and counter part 14, and a detecting part 3 for detecting an absolute position in one rotation. The multi rotation signal is obtained even when a main power source is turned OFF. The encoder is also provided with control means 50, 60 for controlling the operational amplifiers so that a current flowing to control terminals 21a, 21b of the operational amplifiers is increased when the main power source is ON and decreased when the main power source is OFF. Accordingly, the operational amplifiers operate with a high response characteristic when the main power source is ON, and consume less power when the main power source is OFF.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-rotation absolute encoder that can obtain a multi-rotation signal even when the main power supply is off.

[0002]

2. Description of the Related Art Conventionally, this type of multi-turn absolute
As the encoder, for example, the one shown in FIG. 6 is known. This encoder has a main power supply 110 and a main power supply 11
A backup power supply 120 that is charged when the power is turned on to generate a drive power supply 130, and a two-phase signal (two rectangular-wave signals RA that are 90 ° out of phase with each other according to the number of revolutions of the detection target (for example, a magnet disk)). , RB) is output. Further, the encoder detects the absolute position of the detected object within one rotation when the main power supply 110 is turned on or the request signal is input, and outputs the absolute position signal ABS and the absolute detection unit 150, and the amount of movement from the absolute position. Is detected and an incremental amount detection signal INC is output, an incremental detection unit 160, a counter unit 170, and a signal processing unit 180. The counter section 170 receives the signal RA,
The number of rotations of the detected object is counted based on RB, and a multi-rotation signal (binary data) representing the number of rotations is output. The signal processing unit 180 uses the absolute position signal ABS and the movement amount signal IN.
Based on C respectively, an absolute signal (ABS signal) indicating the absolute position within one rotation and an incremental signal (INC signal) indicating the movement amount from the absolute position are output. A signal representing the absolute position within one rotation (for example, binary data representing 0 to 2047 when one rotation is divided into 2048) is obtained from the absolute signal (ABS signal) and the incremental signal (INC signal).

Multi-rotation detector 140 and counter 170
Are constantly driven by the drive power supply 130. on the other hand,
The absolute detector 150, the incremental detector 160, and the signal processor 180 are driven by the main power supply 1.

The multi-rotation detecting section 140 is 90 degrees out of phase with each other and is generated from signal generating sections 190A and 190B and signal generating sections 190A and 190B, respectively, which generate sinusoidal signals corresponding to the number of revolutions of the object to be detected. It has operational amplifiers 191A and 191B for converting the output sine wave signals into rectangular wave signals RA and RB.

In the above encoder, the position of absolute position within one rotation 0 and the position of change of the multi-rotation signal are made to exactly coincide with each other at the time of manufacture, that is, when one rotation is divided into, for example, 2048, the absolute position within one rotation is 2047 → It is difficult and impractical for the multi-rotation signal to be incremented at the same time when it changes to zero.

Therefore, a correction method for matching the position of absolute position 0 within one rotation with the changed position of the multi-rotation signal is disclosed in Japanese Patent Laid-Open No. 3-287014. A description of this correction method is omitted. In order to match the two positions by the correction method, the amount of phase shift between the absolute position signal ABS and the multi-rotation information signal (two-phase signals RA and RB) must be within the standard value. is necessary. If the phase shift amount is out of the standard value, the correct absolute position cannot be obtained, and the absolute position detection accuracy is deteriorated.

[0007]

In the above-mentioned prior art, in order to set the phase shift amount to a value within the standard and enable detection of the absolute position with high accuracy, synchronization is performed with the absolute position within one rotation. It is necessary to reduce the phase delay of the multi-rotation information signal with respect to the absolute position signal so that the multi-rotation information signal is input to the counter unit 170. Therefore, (1) a method of increasing the current consumption of the operational amplifier, (2) a method of decreasing the rotational speed of the object to be detected, (3) using an operational amplifier with excellent response characteristics, (4) high speed and It is conceivable to use an operational amplifier with low power consumption. But,
In the case of (1), since the power consumption of the operational amplifiers 191 and 192 increases, the backup power supply 120 can shorten the backup time and the life of the power supply 120, which is short for maintenance for replacing the power supply 120. The cost required will increase. In the case of (2), the performance of the encoder deteriorates. In the case of (3),
The same problem as in the case of (1) occurs. In the case of (4), since the operational amplifier becomes expensive, the product cost increases.

The present invention has been made in view of the above circumstances, and its object is to realize highly accurate absolute position detection at low cost, enable long-term backup when the main power supply is off, and perform maintenance. It is to provide a multi-turn absolute encoder with reduced cost.

[0009]

In order to solve the above-mentioned problems, a multi-rotational absolute encoder according to the invention of claim 1 generates a signal according to the number of revolutions of a main power source and an object to be detected. Unit and a multi-rotation detecting unit that has an operational amplifier that converts the signal into a rectangular wave signal, outputs the rectangular wave signal, and calculates the rotation speed based on the rectangular wave signal, and calculates the rotation speed. A multi-revolution signal output unit that outputs a multi-revolution signal that represents, a backup power supply that is charged when the main power supply is turned on, and that constantly drives the multi-revolution detection unit and the multi-revolution signal output unit, and is driven by the main power supply,
In a multi-rotation absolute encoder that includes an absolute position detection unit that detects an absolute position of the detected object within one rotation and outputs a signal of the absolute position, and that obtains the multi-rotation signal even when the main power supply is off, It is characterized by further comprising control means for controlling the current flowing through the operational amplifier so that the current flowing through the operational amplifier increases when the main power supply is on and decreases when the main power supply is off.

When the main power supply is turned on, the current flowing through the operational amplifier increases, so that the operational amplifier operates with high response characteristics. As a result, the phase delay of the rectangular wave signal output from the multi-rotation detection unit with respect to the absolute position signal output from the absolute position detection unit is reduced, and the rectangular wave signal synchronized with the absolute position within one rotation is reduced. Is output from the multi-rotation detector. When the main power supply is off, the current flowing through the operational amplifier is small, so the power consumption in the operational amplifier is small, and the backup power supply enables backup for a long time. It should be noted that when the main power supply is turned off, the rotational speed of the object to be detected may be calculated and held by the multi-rotation signal output unit, and there is no problem even if the response characteristic of the operational amplifier is deteriorated.

[0011]

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

FIG. 1 is a block diagram showing a schematic structure of a multi-turn absolute encoder according to an embodiment of the present invention, FIG. 2 is a plan view showing a schematic structure of the encoder, and FIG.
FIG. 3 is a side view showing a schematic configuration of the encoder.

As shown in FIGS. 2 and 3, the multi-rotation absolute encoder (hereinafter, simply referred to as an encoder) includes a code plate 1, three detectors 2 to 4 and a rotary shaft 5 for rotating the code plate 1. Prepare

The code plate 1 has an absolute first track 6 having a one-track absolute pattern.
And an incremental second track 7 arranged inside the track 6 for generating an incremental signal.
And the third track 8 for measuring the number of revolutions are independently formed concentrically. Tracks 6 and 7 are optical black and white patterns. The track 8 has a magnetic SN pattern and is composed of a magnet disk.

The detection unit 2 is a third unit that rotates together with the code plate 1.
Two-phase signals (90 ° to each other) according to the number of rotations of the track 8
It is a multi-rotation detecting unit that outputs two rectangular wave signals RA and RB) having a phase shift.

The detection unit 3 is an absolute detection unit that detects the absolute position within one rotation of the object to be detected along the first track 6 when the main power source is turned on or the request signal is input, and outputs the absolute position signal. is there.

The detection unit 4 detects the movement amount from the absolute position as the second amount.
It is an incremental detection unit that detects along the track 7 and outputs a signal of the movement amount.

The encoder, as shown in FIG.
It includes a main power supply 11, a backup power supply 12 that is charged when the main power supply 11 is turned on, and makes a drive power supply 13, a counter unit 14, and a signal processing unit 15. Counter unit 14
Outputs the multi-rotation signal (binary data) representing the number of revolutions of the object to be detected based on the signals RA and RB. The signal processing unit 15 is based on the absolute position signal ABS and the movement amount signal INC, respectively, and outputs an absolute signal (ABS signal) indicating the absolute position within one rotation and an incremental signal (IN indicating the movement amount from the absolute position).
C signal). By the absolute signal (ABS signal) and the incremental signal (INC signal),
A signal representing an absolute position within one rotation (for example, one rotation is 204
In the case of eight divisions, binary data representing 0 to 2047) is obtained.

The multi-rotation detecting section 2 and the counter section 14 are constantly driven by the drive power supply 13. On the other hand, the absolute detector 3, the incremental detector 4, and the signal processor 15 are driven by the main power supply 11.

The multi-rotation detecting section 2 detects the magnetic field of the third track 8 rotating together with the code plate 1 to detect the code plate (object to be detected).
Magnetic sensors (signal generators) 20A and 20B that output two-phase signals according to the number of rotations of 1 and magnetic sensor 20A,
Operational amplifiers 21A, 21 for converting the sinusoidal signals respectively output from 20B into rectangular wave signals RA, RB
B and. The magnetic sensors 20A and 20B are composed of a magnetoresistive element and a bias magnet, and are arranged on the third track (magnet disk) 8 at a 90 ° phase shift.
Output terminals 20a, 20b of the magnetic sensors 20A, 20B
Output sine-wave signals having a phase difference of 90 ° from each other. One cycle of each sinusoidal signal corresponds to one rotation of the code plate (object to be detected) 1.

Programmable operational amplifiers are used as the operational amplifiers 21A and 21B. Operational amplifier 21
The inverting input terminals of A and 21B are magnetic sensors 20A and 20B.
Of the output terminals 20a and 20b.
The voltage at the connection point of the resistors R6 and R7 divided by the resistors R5 to R8 is applied to the non-inverting input terminals of the operational amplifiers 21A and 21B.

The control terminals 21a and 21b of the operational amplifiers 21A and 21B are grounded via the first resistors R1 and R3, respectively, and the first resistors R1 and R3 are also connected.
Is connected to the ground via the second resistors R2 and R4 and the transistors Tr1 and Tr2 connected in parallel.
The bases of the transistors Tr1 and Tr2 are connected to the main power supply 11 via the resistors R9 and R15 so that the transistors Tr1 and Tr2 are turned on when the main power supply 11 is turned on and turned off when the main power supply 11 is turned off. Between resistors R10 and R
16 are connected.

The current flowing through the operational amplifier 21A is the main power supply 1
The control means 50 for controlling the operational amplifier 21A is configured by the resistors R1, R2, R9, R10 and the transistor Tr1 so as to increase when the switch 1 is on and decrease when the switch 1 is off. Similarly, the control means 60 for controlling the operational amplifier 21B is controlled by the resistors R3, R4, R15, R16 and the transistor Tr2 so that the current flowing through the operational amplifier 21B increases when the main power supply 11 is on and decreases when the main power supply 11 is off. It is configured.

Next, the operation of the above embodiment will be described.

When the main power supply 11 is turned on, the transistor T
Since r1 and Tr2 are conductive, operational amplifiers 21A and 21A
The control terminals 21a and 21b of B are connected to the first resistor R
1 and R3, and the second resistors R2 and R4 and transistors Tr1 and Tr2, respectively. Therefore, the operational amplifiers 21A, 2
The current (set current: Iset) flowing through the 1B control terminals 21a and 21b increases.

FIG. 4 shows the relationship between the set current (Iset) flowing through the control terminals 21a and 21b and the slew rate, and FIG. 5 shows the set current (Iset) and consumption current (Iq).
And the relationship with.

As is apparent from FIG. 4, when the set current (Iset) flowing through the control terminals 21a and 21b increases, the slew rate (maximum change speed of the output voltage).
Becomes larger and the response characteristics are improved, so that the operational amplifiers 21A and 21B operate with high response characteristics when the main power supply 11 is turned on. As a result, the phase delay of the two-phase signals (rectangular wave signals RA and RB) output from the multi-rotation detection unit 2 with respect to the absolute position signal ABS output from the absolute detection unit (absolute position detection unit) 3. Less,
Two-phase signals RA and RB synchronized with the absolute position within one rotation are output from the multi-rotation detection unit 2.

When the main power is off, the transistor Tr
Since 1 and Tr2 are in non-conduction state, the operational amplifier 21
The control terminals 21a and 21b of A and 21B are the first
Of the resistors R1 and R3 are grounded.
Therefore, the set current (Iset) flowing through the control terminals 21a and 21b becomes small.

As is apparent from FIG. 5, the set current (I
The current consumption (Iq) also decreases with the decrease of the set), so that when the main power supply 11 is off, the operational amplifier 21A,
The power consumption in 21B becomes small, and backup power supply 1
2 enables backup for a long time.

As described above, according to the above embodiment, when the main power source 11 is turned on, the control terminals 21a and 21b are controlled.
Since the set current (Iset) flowing through the operational amplifiers 21A and 21B operates with high response characteristics, the absolute position signal A output from the absolute detector 3 is detected.
The phase delay of the two-phase signals RA and RB output from the multi-rotation detector 2 with respect to BS is reduced. As a result, when the correction method disclosed in the above publication, that is, the correction method for matching the position of the absolute position within one rotation 0 and the changed position of the multi-rotation signal is used, the signal processing unit 15 outputs. Absolute position signal (ABS signal) and movement amount signal (I
NC signal), which is a signal (binary data) representing the absolute position within one rotation, and the position of absolute position 0 within one rotation, and a multi-rotation signal (binary) indicating the number of rotations of the detected object output from the counter unit 14. (Data) matches the changing position, and the absolute position is detected with high accuracy.

Therefore, highly accurate absolute position detection can be realized at low cost without using an expensive operational amplifier having excellent response characteristics.

When the main power supply is off, the set current (Iset) becomes small, and the operational amplifiers 21A and 21B are set.
Power consumption is reduced, backup power supply 12
Backup is possible for a long time, and the life of the backup power supply 12 is extended.
It is possible to reduce the cost required for maintenance for exchanging.

In the above-described embodiment, in order to detect the clockwise and counterclockwise rotation speeds of the object to be detected, the multi-rotation detecting section 2 has a two-phase signal R which is 90 ° out of phase with each other.
Although it is configured to output A and RB, the present invention is not limited to such a configuration. That is, the multi-rotation detection unit 2 has one magnetic sensor and one operational amplifier,
It may be configured to output only one sinusoidal signal RA corresponding to the number of rotations of the detected object in one direction.

Further, in the above-mentioned one embodiment, the number of revolutions of the object to be detected is detected magnetically, but the present invention is also applied to the case where the number of revolutions is detected by an optical method or another method. .

Further, in the above embodiment, the absolute position within one rotation of the object to be detected is detected optically, but the present invention is also applicable to the case where the detection is performed by a method other than the optical method. To be done.

Further, in the above embodiment, analog switches, relays or the like may be used instead of the transistors Tr1 and Tr2.

[0037]

As described above, according to the multi-turn absolute encoder according to the invention of claim 1,
When the main power supply is turned on, the current flowing through the operational amplifier increases, so that the operational amplifier operates with high response characteristics. As a result, the phase delay of the rectangular wave signal output from the multi-rotation detection unit with respect to the absolute position signal output from the absolute position detection unit is reduced, and the rectangular wave signal synchronized with the absolute position within one rotation is reduced. Is output from the multi-rotation detector.
When the main power supply is off, the current flowing through the operational amplifier is small, so the power consumption in the operational amplifier is small, and the backup power supply enables backup for a long time.

Therefore, highly accurate absolute position detection can be realized at low cost, backup can be performed for a long time when the main power supply is off, and maintenance costs can be reduced.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a multi-turn absolute encoder according to an embodiment of the present invention.

FIG. 2 is a plan view showing a schematic configuration of a multi-turn absolute encoder according to one embodiment.

FIG. 3 is a side view showing a schematic configuration of a multi-turn absolute encoder according to an embodiment.

FIG. 4 is a graph showing a relationship between a set current of an operational amplifier and a slew rate.

FIG. 5 is a graph showing the relationship between the set current and the consumption current of the operational amplifier.

FIG. 6 is a block diagram showing a schematic configuration of a conventional multi-rotation absolute encoder.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 code plate (object to be detected) 2 multi-rotation detection unit 3 absolute detection unit (absolute position detection unit) 11 main power supply 12 backup power supply 14 counter unit (multi-rotation signal output unit) 20A, 20B magnetic sensor (signal generation unit) 50 , 60 Control means

Claims (1)

[Claims] 1. A main power supply, a signal generator that generates a signal according to the number of revolutions of the object to be detected, and an operational amplifier that converts the signal into a rectangular wave signal, and outputs the rectangular wave signal. A multi-rotation detection unit, a multi-rotation signal output unit that calculates the number of revolutions based on the rectangular wave signal and outputs a multi-rotation signal that indicates the number of revolutions, and the multi-rotation is charged when the main power supply is turned on. A backup power supply that constantly drives the detection unit and the multi-rotation signal output unit, and is driven by the main power supply,
In a multi-rotation absolute encoder that includes an absolute position detection unit that detects an absolute position of the detected object within one rotation and outputs a signal of the absolute position, and that obtains the multi-rotation signal even when the main power supply is off, So that the current flowing through the operational amplifier increases when the main power supply is on and decreases when the main power supply is off,
A multi-rotation absolute encoder comprising a control means for controlling a current flowing through the operational amplifier.