JP3144877B2 - Backup type absolute position encoder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backup type absolute position encoder used for an industrial robot or the like.

[0002]

2. Description of the Related Art Conventionally, in an industrial robot, an absolute code for detecting a rotation angle within one rotation and a Z-phase for outputting a signal once per rotation are engraved on a rotating disk, and the operation power is cut off (hereinafter referred to as backup time ) Mainly uses an absolute position encoder that counts the Z-phase signal with an electric circuit built in the encoder. However, since the configuration is complicated and expensive, the absolute code is abolished, and an all-backup absolute position encoder that counts the signal of the incremental encoder by an electric circuit inside the encoder has been commercialized.

This backup type absolute position encoder is an optical encoder, as shown in FIG.
The light from D1 passes through a slit group 5 of a rotating slit 3 provided on the rotating disk 2 and a fixed slit 4 at the rear, reaches a light receiving element 6, and extracts the rotation of the encoder as an electric signal. The output of the light receiving element 6 is counted by a rotation counter inside the signal processing IC 8 on the control board 7 to detect the rotation amount of the encoder shaft.

[0004] In addition, the motor of the industrial robot is provided with a brake, and when the power is cut off, the rotation is stopped. However, the rotation of the encoder cannot be avoided due to the impact on the robot arm. For this reason, the backup type absolute position encoder is designed to back up with a battery or the like even when the power is cut off and stopped, to operate a necessary electric circuit on the control board 7, and to know the absolute position. Normally, during backup, the LED 1 is driven intermittently to reduce current consumption.

FIG. 4 is a block diagram showing a configuration of an electric circuit in a conventional backup type absolute position encoder. In FIG. 4, light from LED 1 passes through slit group 5 and reaches light receiving element 6. The outputs of the light receiving elements 6a and 6b are converted into rectangular wave signals by the waveform shaping circuits 11a and 11b. These signals are called an A-phase output and a B-phase signal, and become an external output signal when an operation power is applied (hereinafter, referred to as a normal operation). The A-phase output and the B-phase signal become an up signal a and a down signal b by the quadruple circuit 12, and are counted by the back-up rotation amount counter 13. Further, a timing generating circuit 14 for intermittently driving the LED 1 during the backup operation is provided for the purpose of reducing power consumption. This is LED1
Is overwhelmingly large current consumption. The above-described waveform shaping circuits 11a and 11b, the quadruple circuit 12, the rotation counter 13 and the timing generation circuit 14 constitute a signal processing IC 7.

FIG. 5 shows A-phase and B-phase outputs and an LED drive signal p.
Shows the relationship. In FIG. 5, in order to correctly count the A-phase output and the B-phase output, the period T of the LED drive signal p is calculated from the minimum time at which the change point of the A-phase output and the B-phase output appears.
₀ (hereinafter referred to as sampling period) must be short.

[0007]

[SUMMARY OF THE INVENTION However, in the conventional backed absolute position encoder, increasing the sampling period T ₀ in order to reduce power consumption at the time of backup, correctly countable upper limit rotation speed of the rotation of the encoder N ₀ is to be small. The sampling period T ₀ depends on the battery capacity and the required backup time.
Is determined, the upper limit rotation speed N ₀ is determined, but there is a problem that it is difficult to obtain a practically sufficient upper limit rotation speed N ₀ .

The present invention solves the above-mentioned conventional problem. When the drive power of the industrial robot is cut off and the backup state is established, a practically sufficient upper limit rotational speed N ₀ and backup time are set to standard values. It is an object of the present invention to provide a backup type absolute position encoder that can be realized with a battery configuration.

[0009]

In order to solve the above-mentioned problems, a backup type absolute position encoder according to the present invention comprises:
Incrementer that of between the light emitting means and light receiving means, having a first rotation amount detecting means for detecting the amount of rotation of the rotary disc with intervening rotation slit provided in the rotary disk
Mental backup type absolute position encoder,
A second rotation amount for providing a rotation slit coarser than the rotation slit on the rotation disk and interposing the coarse rotation slit between a second light emitting unit and a light receiving unit to detect a rotation amount of the rotation disk. Detecting means for stopping the first light emitting means and the light receiving means in a backup state
And a driving means for intermittently driving at least the second light emitting means at a cycle necessary for correctly detecting the coarse rotating slit.

[0010]

According to the above construction, in the backup state, at least the second light emitting means is intermittently driven by the driving means at a long period necessary for correctly detecting the coarse rotation slit, and is rotated by the second rotation amount detecting means. Since the rotation amount of the disk is detected, the current consumption of the encoder can be reduced by increasing the intermittent drive cycle of the light emitting means during backup, and the backup time can be extended with a standard battery configuration, and The practically sufficient upper limit rotational speed in the backup state in which the drive power supply of the robot is cut off is also guaranteed.

[0011]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of an electric circuit in a backup absolute position encoder according to one embodiment of the present invention. In Figure 1, the backup power supply V _B is LED 21a, is connected to the timing generator circuit 22 via a series circuit of 21b, at the time of backup, LED 21a by the timing generation circuit 22, 21b and is intermittently driven. The backup power supply V _B is the light receiving element 23a, 23b, 23
c and 23d in parallel, respectively, through the waveform shaping circuits 24a and 24d.
b, 24c, 24d, respectively, the light from the LED 21a is received by the light receiving elements 23a, 23b, respectively, and waveform-shaped by the waveform shaping circuits 24a, 24b to form A-phase, B-phase rectangular waves, Similarly, the light from the LED 21b is received by the light receiving elements 23c and 23d, respectively, and the waveform shaping circuit 24c and
At 24d, waveforms are respectively shaped to form C-phase and D-phase rectangular waves. These LEDs 21a, 21b and light receiving elements 23a, 23b,
A rotating disk 25 is provided between 23c and 23d. The rotating disk 25 has a first rotating slit for generating A-phase and B-phase outputs, and a second rotating slit for generating C-phase and D-phase outputs.
The second rotating slit has a slit structure that is sufficiently coarser than the first rotating slit that generates the A-phase and B-phase signals.

The waveform shaping circuits 24a and 24b are quadruple circuits.
The A-phase and B-phase outputs from the waveform shaping circuits 24a and 24b are connected to an AB rotation amount counter 27a via a 26a.
The signal a becomes an AB up signal and an AB down signal, and is counted by the AB rotation amount counter 27a. Also, the waveform shaping circuit 24c,
24d is connected to an AB rotation amount counter 27b via a quadruple circuit 26b, and the C-phase and D-phase outputs from the waveform shaping circuits 24c and 24d become a CD up signal and a CD down signal in the quadruple circuit 26b, and an AB rotation amount counter. Counted at 27b. As described above, the AB rotation amount counters 27a and 27b are output from the LEDs 21a and 21b.
b, a rotation amount detecting means for detecting the rotation amount of the rotating disk 25 is provided, and the rotation amount counter is an AB rotation amount counter.
27a and a CD rotation amount counter 27b, and counts the corresponding up signal and down signal. That is, a coarse second rotating slit is provided on the rotating disk 25 in addition to the dense first rotating slit, and a circuit for counting dense signals and a circuit for counting coarse signals are provided.

Further, an adder 28 composed of an OR gate to which the CD up signal and the CD down signal from the quadruple circuit 26b are input has its output terminal connected to the AB rotation amount counter 27a. This, LED 21a, the contents of even CD rotation amount counter 27b as an encoder is wound by the upper rotational speed N ₀ in the backup state by consideration of the driving cycle T ₁ of the 21b is said to be correct, AB rotation amount counter 27a There is a possibility that the contents will be shifted. For this reason, a function is provided for resetting and restoring the AB rotation amount counter 27a at the rising and falling edges of the sum signal of the CD up signal and the CD down signal. Therefore, immediately after the drive power of the industrial robot is turned on, the CD rotation counter
It is necessary to operate the robot a little with the contents of 27b (that is, a coarse absolute position) and to return the contents of the AB rotation amount counter 27a to a correct value before taking in the absolute position. The above timing circuit 22, waveform shaping circuits 24a, 24b, 24c, 24
d, quadrupling circuits 26a, 26b, AB rotation amount counters 27a, 27
b and the adder 28 constitute a signal processing IC 29.

FIG. 2 is a diagram showing output signal waveforms at respective main parts of the electric circuit of the backup type absolute position encoder shown in FIG. 1, wherein phases A to D when the encoder rotates once at a constant speed.
The relationship between the phase output signal and the LED drive signal P is shown.
In FIG. 2, the repetition period of the C phase and the D phase is set to ４ rotation for simplicity. The cycle T1 of the LED drive signal P is C
By setting the phase and the D-phase change points to be less than the minimum time (ie, 1/16 rotation), the C- and D-phases are correctly counted.

With the above configuration, at the time of backup, the circuit is operated at a speed at which only coarse signals can be counted, and at the start of operation, the industrial robot is operated based on the contents of the coarse rotation counter 27b (that is, at a coarse absolute position). Let it. Then, as a result of the operation, the encoder rotates, and when the coarse signal from the coarse rotary slit changes first, the dense AB rotation amount counter 27a is set to a correct value, and the robot is operated at the fine absolute position.

In other words, the encoder of the industrial robot has its drive power cut off and its rotation is suppressed by the brake in the backup state, and the encoder does not rotate at high speed. Therefore, the encoder is operated even when it is stopped so that the absolute position can be determined. At this time, in the backup state, the current consumption of the encoder is reduced by intermittently driving the LEDs 21a and 21b by the driving means at a long period necessary to correctly detect the coarse rotating slit. When the driving power of the industrial robot is turned on and the operating power is supplied, the contents of the AB rotation counter 27a corresponding to the first rotating slit are ignored, and the CD rotation counter corresponding to the second rotating slit is ignored. The robot is operated with the contents of 27b (that is, at a coarse absolute position). Then, the AB rotation amount counter 27a is returned to the initial value at the signal change point of the C-phase and D-phase outputs, and thereafter the operation at the complete absolute position becomes possible.

Therefore, when the drive power of the industrial robot is cut off and the backup state is established, a practically sufficient upper limit rotational speed N ₀ and a long backup time can be realized with a standard battery configuration. Thus, an inexpensive backup type absolute position encoder can be obtained.

[0018]

As described above, according to the present invention, it is possible to provide an inexpensive absolute position encoder in which the number of revolutions sufficient for normal use at the time of backup is guaranteed and the backup time is extended.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an electric circuit in a backup absolute position encoder according to one embodiment of the present invention.

2 is an output signal waveform diagram in an electric circuit of each main part of the backup type absolute position encoder of FIG.
FIG. 6 is a timing chart of a D-phase output and an LED drive signal P.

FIG. 3 is a configuration diagram of a conventional backup type absolute position encoder.

FIG. 4 is a block diagram showing a configuration of an electric circuit in a conventional backup-type absolute position encoder.

5 is an output signal waveform diagram in an electric circuit of each main part of the backup type absolute position encoder of FIG.
FIG. 4 is a timing chart of a phase output and an LED drive signal.

[Explanation of symbols]

 21a, 21b LED 22 Timing generation circuit 23a, 23b, 23c, 23d Light receiving element 24a, 24b, 24c, 24d Waveform shaping circuit 25 Rotating disk 26a, 26b Quadruple circuit 27a, 27b Rotation amount counter 28 Signal adder 29 Processing circuit IC

Claims (1)

(57) [Claims] 1. A method according to claim 1, wherein the first light-emitting means and the light-receiving means include:
An incremental backup type absolute position encoder having first rotation amount detecting means for detecting a rotation amount of the rotary disk through a rotary slit provided in the rotary disk, wherein the rotary disk is coarser than the rotary slit. And a second rotation amount detection means for detecting the rotation amount of the rotating disk by interposing the coarse rotation slit between the second light emitting means and the light receiving means, and providing the second rotation amount in the backup state . One light emitting means
An incremental backup type absolute position encoder provided with a driving unit for intermittently driving at least the second light emitting unit at a cycle necessary for stopping the light receiving unit and detecting the coarse rotary slit correctly.