JP2634590B2 - Optical encoder for detecting the displacement of the working end of a robot - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an optical encoder for detecting a displacement of a working end of a robot which detects a displacement of a working end of an industrial robot or the like as an angular displacement.

2. Description of the Related Art A prior art for detecting an angular displacement of an object with high accuracy using an optical disk is known in, for example, Japanese Patent Application Laid-Open No. 60-100013. High-precision detection of angular displacement
Required at the working end of a robot. In such prior art, an optical disk is irradiated with laser light, the reflected light is detected by a light receiving element, and pulses corresponding to the pits formed on the optical disk from the light receiving element are counted by a counter. It is configured to be.

Problems to be Solved by the Invention In such prior art, when a power failure occurs, the contents of the counter are not retained, and therefore, when the power is turned on after the recovery from the power failure, the operator takes a lot of troublesome operation of the counter. The count value must be set corresponding to the angular displacement position of the object.

In particular, at the working end of an industrial robot or the like, if a power failure occurs during work in a narrow place, it is difficult for an operator to perform work to set the count value of the counter so as to correspond to the angular displacement position. If the count value of the counter does not accurately correspond to the angular displacement position, the working end contacts the surroundings in a narrow place, and there is a possibility that the working end itself and the surroundings may be damaged. For example, an index is provided in an optical encoder, and when power is turned on after a power failure such as a power failure, the work end is moved to detect the position of the index, and the index is automatically initialized based on the position of the index. Is also possible.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical encoder for detecting a displacement of a working end of a robot, which can easily, accurately and safely perform initialization from a power failure such as a power failure.

Means for Solving the Problems The present invention relates to optical disks 40, 45 which rotate in response to the displacement of the working end of a robot, and comprises a plurality of tracks T4, T5, concentrically about an axis 7.
A plurality of pits 43 and 48 are formed at equal intervals in the circumferential direction on the outermost track T4 and 47, and a plurality of pits 43 and 48 are formed on the middle track T5 and 50 in the circumferential direction. At equal intervals, a plurality of pits 41, less than the outermost pits 43, 48
The innermost track T6 is provided with magnetically detected parts 42, 10 at the same number as the intermediate pits 41, 51 at equal intervals in the circumferential direction. 45, the laser light sources 12, 13, 16 for irradiating the outermost pits 43, 48 and the intermediate pits 41, 51 with laser light, and the laser light irradiating the outermost pits 43, 48 with a track T4, A pair of first light receiving elements 21 and 22 for receiving reflected light from positions shifted in the circumferential direction along 47 and deriving outputs having a phase difference corresponding to the rotation direction of the optical disks 40 and 45, respectively; According to whether the output from one of the light receiving elements 21 and 22 is ahead or behind the other output,
First and second counting means 27 and 29 for counting up and down the outputs from the first light receiving elements 21 and 22, and the laser light applied to the intermediate pits 41 and 51, respectively.
The second light receiving element 23 for detecting the reflected light is arranged to be displaced in the circumferential direction along the innermost track T6 to detect the magnetically detected parts 42 and 10 and to detect the magnetically detected parts 42 and 10 in the rotation direction of the optical disks 40 and 45. A pair of magnetic sensing elements 5, 6 for respectively deriving outputs having a corresponding phase difference, and according to whether the output from one of the magnetic sensing elements 5, 6 is ahead or behind the phase of the other output. A second counting means 33, 35 for counting up or down the output from the magnetic detecting elements 5, 6; and a battery for constantly energizing the magnetic detecting elements 5, 6 and the second counting means 33, 35. 37, a motor 1 for driving the working end of the robot to be displaced, and when receiving the reflected light from the intermediate pits 41, 51 in response to the output from the second light receiving element 23 during power-on. ,
The count values of the first counting means 27, 29 are set to predetermined values as the angular displacement positions of the optical discs 40, 45 corresponding to the positions of the pits 41, 51, and when the power is turned on from the power deactivated state, the motor 1 When the reflected light from the intermediate pits 41 and 51 is received in response to the output from the second light receiving element 23 due to the angular displacement of the optical discs 40 and 45, the working end of the robot is displaced in a predetermined direction. And initialization means 38 for setting the count values of the first count means 27, 29 to values corresponding to the count values of the second count means 33, 35, which continue to detect angular displacement even in the power deactivated state. Is an optical encoder for detecting displacement of the working end of the robot.

According to the present invention, the optical discs 40, 45 which rotate in accordance with the displacement of the working end of the robot are the plurality of concentric tracks T4, T5, T6; The pits 41, 51 are equally spaced in the circumferential direction on the intermediate tracks T5, 50.
The innermost track T6 is provided with the same number of magnetically detected portions 42, 10 as the pits 41, 51 at equal intervals in the circumferential direction. The magnetic detection elements 42 and 10 are detected by the magnetic detection elements 5 and 6 such that their outputs have a phase difference corresponding to the rotation direction of the optical disks 40 and 45. The second counting means 33 and 35 increase the output from the magnetic detection elements 5 and 6 according to whether the output from one of the magnetic detection elements 5 and 6 is ahead or behind the output of the other. Count or count down.

Since the magnetic detecting elements 5 and 6 and the second counting means 33 and 35 are always energized by the battery 37 even when the power is deactivated such as during a power outage, the first light receiving elements 21 and 22 and First
The detection of the angular displacement can be continued even at the time of power deactivation where the angular displacement of the counting means 27, 29 is not performed. The detection of the angular displacement can be more than one rotation. When the power is turned on, such as when power is restored, the initialization means 38 displaces the working end by the motor 1 in a predetermined direction, and the corresponding optical discs 40, 4 are displaced.
In response to the output from the second light receiving element 23 due to the angular displacement of 5,
When the reflected light from the intermediate pits 41, 51 is received, the count value of the first counting means 27, 29 is set to a value corresponding to the count value of the second counting means 33, 35. Also, when the working end of a robot for industrial use is displaced by an external force during power deenergization, the magnetic detection elements 5 and 6 are moved as the magnetically detected parts 42 and 10 move.
, And counted by the second counting means 33, 35, and the detection as the position of the object can be continued.
Since a plurality of intermediate pits 41, 51 and magnetically detected parts 42, 10 are provided at equal intervals in the circumferential direction, the initialization means
38, the amount of angular displacement by the motor 1 driven by the motor 38 can be reduced, and even if the detection accuracy is improved at a sufficiently low speed, the setting can be performed in a short time. The displacement can also be reduced.

Since the magnetically detected portions 42, 10 are arranged in smaller numbers than the pits 43, 48 formed at equal intervals in the circumferential direction on the outermost tracks T4, 47 of the optical disks 40, 45, The count values of the second counting means 33 and 35 may be relatively small. For this reason, the power consumption of the second counting means 33, 35 is small,
The load on the battery 37 is light, and the power supply can be continued for a long time. However, the magnetically detected part 4
The accuracy in magnetically detecting 2, 10 by the magnetic detecting elements 5, 6 is the accuracy in optically detecting the pits 43, 48; 41, 51 by the light receiving elements 21, 22, 23. Not as high. Intermediate pits 41 and 51 are provided corresponding to the magnetically detected portions 42 and 10, respectively. At the time of detection, the count values of the first counting means 27 and 29 are at the angular displacement positions of the optical disks 40 and 45. Since the value is set to the corresponding value, the angular displacement of the optical disks 40 and 45 can be detected with high accuracy after this setting.

Normally, that is, in the state where no power failure occurs, the outermost pits 43, 48 and the middle pits 41, 51 of the optical disks 40, 45 are irradiated by the laser light sources 12, 13, 16 by the laser light sources 12, 13, 16.
The reflected light is detected by the first light receiving elements 21 and 22 and the second light receiving element 23, respectively. The outputs from the first light receiving elements 21 and 22 are counted by first counting means 27 and 29, and the reflected light from the intermediate pits 41 and 51 is received in response to the output from the second light receiving element 23. 1 Count values of the counting means 27 and 29 are
Set to the value corresponding to the angular displacement position of 0,45. As described above, the angular displacement of the optical disks 40 and 45 can be detected with high accuracy by using the intermediate pits 41 and 51 as an index.

Embodiment FIG. 1 is a cross-sectional view of an optical encoder having a configuration on which the present invention is based. An optical disc 3 is fixed to an output shaft 2 of a motor 1 for driving a working end of an industrial robot. The optical disk 3 is optically detected by the detecting means 4 and magnetically detected by the magnetic detecting elements 5 and 6.

FIG. 2 is a plan view of the optical disk 3. The optical disk 3 is fixed to the output shaft 2, and the axis 7 of the optical disk 3 coincides with the axis of the output shaft 2. A number of pits 8 are formed on the outermost track T1 of the optical disc 3 at equal intervals in the circumferential direction. One pit 9 is formed in the circumferential direction on the track T2 on the inner peripheral side of the track T1. The magnetically detected portion 10 is fixed to the innermost track T3.
Only one magnetically detected part 10 is provided in the circumferential direction, and thus the number is smaller than the number of the pits 8 of the track T1. The magnetically detected part 10 is realized by, for example, a magnetized ferromagnetic magnetic powder layer. The optical disk 3 is formed by forming pits 8 and 9 on an aluminum layer formed on a base material made of polycarbonate or the like, and providing a transparent protective layer thereon. Tracks T1, T2, and T3 are concentric virtual circles centered on the axis 7 of the optical disk 3.

Referring again to FIG. 1, the laser light from the semiconductor laser light source 12 passes through the translucent reflecting mirrors 13 and 14 and the lens 15,
The pit 8 of the track T1 is irradiated. The laser light from the laser light source 12 is also transmitted from the translucent reflecting mirror 13 to the pit 9 of the track T2 via the reflecting mirror 16, the translucent reflecting mirror 17, and the lens 18. The positions of the lenses 15 and 18 in the radial direction of the optical disk 3 are controlled by a tracking servo mechanism 19. The reflected light of the laser light on the track T1 is
The light is received by the light receiving elements 21 and 22 from the lens 20 via the translucent reflecting mirror 14 from the lens 15. The reflected light of the laser light of the track T2 passes through the translucent reflecting mirror 17 from the lens 18 and is received by the light receiving element 23 from the lens 52. The light receiving elements 21 and 22 for detecting the reflected light of the pit 8 of the track T1 receive the reflected light at a position shifted in the circumferential direction of the optical disk 3 along the track T1. As a result, the outputs of the light receiving elements 21 and 22 have a phase difference corresponding to the rotation direction of the optical disk 3.

FIG. 3 is a simplified perspective view showing the configuration of the optical disk 3 and its vicinity. The magnetic detecting elements 5 and 6 for detecting the magnetically detected portion 10 of the track T3 are circumferentially shifted along the track T3. These magnetic sensing elements 5, 6
Can be realized by, for example, a so-called magnetoresistive element that detects the strength of a magnetic field as a change in resistance. Since the magnetic detecting elements 5 and 6 are arranged so as to be shifted in the circumferential direction along the track T3, the outputs of the magnetic detecting elements 5 and 6 have a phase difference corresponding to the angular displacement direction of the optical disk 3. Having.

FIG. 4 is a block diagram showing an electrical configuration of the optical encoder shown in FIGS. Light receiving element 21,2
The output from 2 is supplied to the angular displacement direction determination circuit 27 via the amplification circuits 25 and 26. When the optical disc 3 is angularly displaced in one direction, the angular displacement direction discriminating circuit 27 derives the output of the light receiving element 21 from the line 28, and counts up and down the up-down counter 29. When the optical disc 3 rotates in the reverse direction, the angular displacement direction discriminating circuit 27 derives the output of the light receiving element 21 from the line 30 and supplies the output to the counter 29 to count down. This allows the counter
The count value of 29 can detect the angular displacement position of the optical disk 3 with high accuracy.

The outputs of the magnetic detection elements 5 and 6 are passed through amplifier circuits 31 and 32,
The angular displacement direction discriminating circuit 33 is provided. When the optical disc 3 is angularly displaced in the one direction, the angular displacement direction discriminating circuit 33 supplies an output from the magnetic detecting element 5 to an up-down counter 35 via a line 34, counts up and counts up. Let them do it. When the optical disk 3 is angularly displaced in the opposite direction, the angular displacement direction discriminating circuit 33 outputs
Is output via a line 36, whereby the down-counting is performed and the counting by the counter 35 is performed. Battery 37 consists of magnetic sensing elements 5 and 6 and amplifier 3
1, 32, the angular displacement direction discriminating circuit 33 and the counter 35 are always energized. The magnetic detection elements 5 and 6 consume less power, and the count value of the counter 35 that consumes less power is smaller than that of the counter 29 described above, so that the power consumption is small, and the capacity of the battery 37 is reduced. can do. The output of the counter 35 is provided to the initialization circuit 38. Light receiving element
The output of 23 is also provided to initialization circuit 38. Initialization circuit
38 sets the count value of the counter 29 to a value corresponding to the angular displacement position of the optical disc 3 and performs initialization.

When the power is normal, that is, when the power is supplied without power failure, the semiconductor laser light source 12 and the counter 29 are operating, and the counter 29 counts the absolute position of the angular displacement of the optical disk 3. .

When the power is deactivated due to a power failure or the like, the semiconductor laser light source 12 does not operate, and the content of the counter 29 is not maintained. Counter 35 and angular displacement direction determination circuit 33
Is always energized by the battery 37, so that the count value of the counter 35 is maintained even during a power failure. When the optical disk 3 is angularly displaced during the power failure and the magnetically detected portion 10 is detected by the magnetic detecting elements 5 and 6, the count value of the counter 35 changes, and thus the angular displacement of the optical disk 3 is changed. Can always be detected.

When the power is turned on, such as when the power outage recovers,
The optical disc 3 is angularly displaced in one predetermined direction by the motor 1. When the pit 9 of the track T2 is detected by the light receiving element 23, the initialization circuit 38 outputs the optical disk 3 which is the absolute position of the robot arm corresponding to the count value of the counter 35.
Is stored in the counter 29 and set. Thereafter, the motor 1 stops, and when the optical disc 3 is thereafter angularly displaced, the count value of the counter 29 becomes:
This indicates the absolute position of the optical disk 3.

In this configuration, since the absolute position is set in the counter 29 by detecting the pit 9 of the track T2, the setting can be performed with high accuracy.

FIG. 5 is a front view of the optical disk 40 according to one embodiment of the present invention. Tracks T4, T5, and T6 correspond to the tracks T1, T2, and T3 of the above-described configuration, respectively. In this configuration, a plurality of pits 41 are arranged at equal intervals on the track T5. The track T6 is provided with a plurality of magnetically detected portions 42 at equal intervals in the circumferential direction. Track T4 has a large number of pits 43
Is formed.

FIG. 6 (1) shows the pit 43 of the track T4, FIG. 6 (2) shows the pit 41 of the track T5, and FIG. 6 (3) shows the magnetically detected portion 42. T4, T5, T6
Shows a state in which it is deployed in the circumferential direction of the optical disk 40,
The left and right positions in FIG. 6 correspond to the angular displacement positions of the optical disc 40. The interval W1 between the pits 41 and the magnetically detected part
42 are equal to each other with respect to the circumferential angle of the optical disk 40. Other configurations are the same as the configurations in FIGS. 1 to 4 described above. According to such a configuration, when the power is turned on at the time of recovery from a power failure or the like, the optical disk 40 may be angularly displaced by the motor 1 at most by an angle corresponding to the intervals W1 and W2. The displacement amount of the working end or the like of the interlocking industrial robot can be made small.

FIG. 7 shows an optical disk 45 according to still another embodiment of the present invention.
FIG. In this embodiment, the aforementioned tracks T1, T
A plurality of tracks 47 are provided in an area 46 corresponding to 4, and each track is provided with a pit 48 corresponding to the pits 8, 43 of the above-described embodiment. The pit 48 extends in the circumferential direction over a range of an angle θ1 about the axis 7.
They are offset in the radial direction. This allows the lens
Even if the position of the spot of the laser beam passing through 15 on the optical disk 45 shifts in the radial direction, the position of the optical disk 45 in the circumferential direction can be detected, and the tracking servo mechanism 19 can be omitted. Will be possible. No pits 48 are formed in the range of the angle θ2. θ1 = θ2 may be satisfied. Similarly, the tracks T2 and T5 of the above-described embodiment are used.
The pits 51 are formed in the plurality of tracks 50 in the area 49 corresponding to the pits 9 and 42 described above. According to such an embodiment, since the tracking servo mechanism 19 can be omitted, the configuration can be simplified.

The configuration of the present embodiment, including the above-described basic configuration, will be described in more detail. More specifically, the optical disk 4 that rotates integrally with the output shaft 2 of the motor 1 that drives the working end of the robot.
Numeral 0,45 is angularly displaced in accordance with the displacement of the working end, and has a plurality of tracks T4, T5, T6; 47, 50 concentrically around the axis 7. A plurality of pit groups are arranged at equal intervals in the circumferential direction on the plurality of tracks T4, 47 on the outer peripheral side. Each pit group extends in the circumferential direction and has a different track T4,4.
There are a plurality of pits 43 and 48 formed so as to be offset from each other in the radial direction. Multiple tracks T5 on the inner circumference,
Reference numeral 50 denotes a number of pit groups smaller than the number of pit groups on the outer peripheral side, extending in the circumferential direction and having different tracks T5, T5.
There is a plurality of pits 41 and 51 forming a group of pits that are aligned in the radial direction while being between 0. The optical encoder includes such optical disks 40 and 45 and a pit 4 on the outer peripheral side.
The laser light source 12, which is a laser light source for irradiating the laser light to 3, 48 and the inner pits 41, 51, the translucent reflecting mirror 13, the reflecting mirror 16, and the reflected light from the outer pit 48 are transmitted in the circumferential direction. A pair of first light receiving elements 21 and 22 for receiving light at positions shifted to
Angular displacement direction discriminating circuit 27 and up-down counter 29, which are first counting means for counting the outputs from first light receiving elements 21 and 22, and second light receiving means for detecting reflected light from inner pits 41 and 51. Element 23 and optical disks 40, 45 are provided on the inner circumference side by the number of pits 41, 51 in the number of pits in the circumferential direction,
The magnetic detection unit 10 is disposed at a predetermined distance from each pit group, a pair of magnetic detection elements 5 and 6 for detecting the magnetic detection unit 10, and the magnetic detection elements 5 and 6. An angular displacement direction discriminating circuit 33 and an up-down counter 35, which are second counting means for counting the output, and a battery 37 for constantly energizing the magnetic detecting elements 5, 6 and the second counting means 33, 35.
In response to the output from the second light receiving element 23 while receiving the reflected light from the intermediate pits 41 and 51 while the power is energized, the count values of the first counting means 27 and 29 are counted by the optical disks 40 and Initializing means for setting a value corresponding to the angular displacement position of 45 and setting the count value of the first counting means 27 and 29 to a value corresponding to the count value of the second counting means 33 and 35 when the power is turned on. And an initialization circuit 38.

Effects of the Invention As described above, according to the present invention, after power-on such as at the time of recovery from a power failure, the optical discs 40 and 45 for detecting the displacement of the working end of the robot as an angular displacement are the intermediate pits 41 and 5.
1 is used as an index, and the working end is displaced by the motor 1 so that the optical discs 40 and 45 are angularly displaced.
The first counting means 27 and 29 are initialized. Intermediate pits 41,51
Since a plurality of optical disks 40 and 45 are provided at equal intervals, the displacement required for initialization can be reduced, and safety in case of stopping due to power failure etc. during work in a narrow place can be achieved. it can. Intermediate pits 41,5 used for position detection at this time
Although 1 is smaller in number than the outermost pits 43 and 48, it can be detected with the same accuracy, and the angular displacement position can be initialized with high accuracy. Even if the working end of the robot is displaced due to external force etc.
The magnetic detection elements 5, 6 which are energized by the battery 37 to move the magnetically detected portions 42, 10 provided corresponding to 1
Detects the angular displacement of the optical disks 40 and 45, and displaces the working end of the robot by the motor 1 when power is turned on.
When the optical discs 40, 45 are angularly displaced and the first counting means 27, 29 are initialized, the angular displacement of one rotation or more is reliably detected using the count values of the second counting means 33, 35. be able to.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an optical encoder having a basic structure of the present invention, FIG. 2 is a plan view of an optical disk 3 of FIG.
FIG. 3 is a simplified perspective view showing the configuration of the optical disk 3 and its vicinity, FIG. 4 is a block diagram showing the electrical configuration of the optical encoder shown in FIGS. 1 to 3, and FIG. FIG. 6 is a plan view of an optical disk 40 according to an embodiment of the present invention, and FIG.
FIG. 7 is a view showing a state where tracks T4, T5 and T6 of the embodiment shown in the figure are developed, and FIG. 7 is a plan view of a part of an optical disk 45 of still another embodiment of the present invention. 2, output shaft, 3, 40, 45 optical disk, 4 detection means, 5, 6 magnetic detection element, 8, 9, 41, 43, 48, 51 pit, 10, 42 ... … Magnetically detected part

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-48717 (JP, A) JP-A-60-70311 (JP, A) JP-A-60-7316 (JP, A) JP-A 60-6073 100013 (JP, A)

Claims (1)

(57) [Claims] An optical disk (40, 45) rotating in response to a displacement of a working end of a robot, comprising a plurality of tracks (T4, T5, T) concentrically about an axis (7).
A plurality of pits 43, 48 are formed at equal intervals in the circumferential direction on the outermost track T4, 47, and a plurality of pits 43, 48 are formed on the middle track T5, 50 in the circumferential direction. At equal intervals,
A plurality of pits 41 and 51, which are smaller than the outermost pits 43 and 48, are formed, and the innermost track T6 is magnetically detected at the same number as the middle pits 41 and 51 at equal intervals in the circumferential direction. The optical disks 40, 45 provided with the parts 42, 10; the laser light sources 12, 13, 16 for irradiating the outermost pits 43, 48 and the intermediate pits 41, 51 with laser light; Regarding the laser light applied to pits 43 and 48,
A pair of first light receiving elements 21 and 22 for receiving reflected light from positions shifted in the circumferential direction along the tracks T4 and 47 and deriving outputs having a phase difference corresponding to the rotation direction of the optical disks 40 and 45, respectively. Up-counting or down-counting the output from the first light-receiving elements 21 and 22 according to whether the output from one of the first light-receiving elements 21 and 22 is ahead or behind the other output. First counting means 27 and 29 for counting the laser light, a second light receiving element 23 for detecting the reflected light of the laser light applied to the intermediate pits 41 and 51, and a circumferential direction along the innermost track T6. Are placed out of alignment,
A pair of magnetic detecting elements 5 and 6 for detecting the magnetically detected portions 42 and 10 and deriving outputs having a phase difference corresponding to the rotation direction of the optical disks 40 and 45, and one of the magnetic detecting elements 5 and 6 Second counting means 33, 35 for up-counting or down-counting the output from the magnetic sensing elements 5, 6 according to whether the output from the phase detector is ahead or behind the other output, A battery 37 for constantly energizing the magnetic detecting elements 5, 6 and the second counting means 33, 35, and a motor 1 for driving to displace the working end of the robot.
While the power is on, responds to the output from the second light receiving element 23,
When receiving the reflected light from the intermediate pits 41 and 51, the first
The count values of the counting means 27 and 29 are set to predetermined values as the angular displacement positions of the optical discs 40 and 45 corresponding to the positions of the pits 41 and 51. The working end of the robot in a predetermined direction,
In response to the output from the second light receiving element 23 due to the angular displacement of the optical discs 40 and 45 and receiving the reflected light from the intermediate pits 41 and 51, the count values of the first counting means 27 and 29 are deactivated. An optical encoder for detecting the displacement of the working end of the robot, comprising: an initialization means for setting a value corresponding to a count value of the second counting means for continuing the angular displacement detection even in the state.