JPH07218239A - Bearing with rotating angle detector - Google Patents

Abstract

PURPOSE:To provide a bearing with a rotating angle detector having small trouble, long life, excellent external appearance shape and safety. CONSTITUTION:A grid pattern 4 in which a light reflectivity is varied according to a predetermined angle pitch thetaP is provided on an end face of an outer race 1. Two sets of light emitting diodes and photodiodes are provided at an inner race 2 side oppositely to the pattern 4. Two light spots S1, S2 generated on the pattern 4 by lights irradiated from the diodes are deviated by thetaP/4. A rotary angle and a rotating direction between the races 1 and 2 are obtained from number of periodic changes and phase difference of the outputs of the photodiodes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing with a rotation angle detector, and more particularly to a bearing with a rotation angle detector equipped with a rotation angle detector for detecting the rotation angle of a rotating wheel of the bearing.

[0002]

2. Description of the Related Art FIG. 16 (a) shows a conventional rotation angle detector 3
6 is a view illustrating a usage state of No. 6, which is a partially cutaway front view showing a joint part 33 of an articulated robot, and FIG. 16B is a partially cutaway side view of FIG. 16A. In the joint part 33 of this multi-joint robot, the rotating shaft 31a provided at the end of one arm 31 is rotated through the bearing 34 in the support hole 32a provided at the end of the other arm 32. It is provided freely. Further, the joint portion 33 is provided with a rotation angle detector 36 for detecting an angle θ between the arms 31 and 32, and a rotation shaft 36 a of the rotation angle detector 36 has a rotation shaft 31 a via a coupling 35. The main body of the rotation angle detector 36 is fixed to the arm 32 via a support member 37. In the rotation angle detector 36, a variable resistor (not shown) whose electric resistance value changes according to the rotation angle θ of the rotation shaft 36a is provided. Based on the electric resistance value, a variable resistor is provided between the arms 31 and 32. Is detected, and the operation of the arms 31 and 32 is controlled.

[0003]

However, in such an articulated robot, many problems of the rotation angle detector 36 and a short life thereof have been problems. This is because the contact of the variable resistor used in the rotation angle detector 36 and the resistor are quickly worn by the violent operation of the articulated robot, and the output of the variable resistor is an analog amount. Therefore, it is susceptible to electrical noise from the outside.

Further, since the rotation angle detector 36 and the support member 37 are largely projected outside the joint 33,
Not only was the external shape poor, but the overhanging part hit the obstacle and was dangerous.

Therefore, a main object of the present invention is to provide a bearing with a rotation angle detector, which has few failures, has a long life, has a good appearance and is safe.

[0006]

A first bearing with a rotation angle detector according to the present invention comprises a grid pattern provided on the rotating wheel side of the bearing, a light source provided so as to face the grid pattern, and And a light detection element for detecting light emitted from the light source and changed by the lattice pattern.

The grating pattern may have its light reflectance changed at a predetermined angular pitch, and the light source and the light detecting element may be provided on the other ring of the bearing. Further, a plurality of the photodetecting elements may be provided, and the direction of each light receiving surface may be deviated from the rotation direction of the lattice pattern.

Further, a plurality of light sources may be provided so as to correspond to the photodetection elements.

Further, a rotation angle calculation means for calculating the rotation angle based on a periodic change in the output of the photodetector may be included.

The second bearing with rotation angle detector of the present invention is provided on the rotating wheel side of the bearing, and the light reflection state of the bearing changes according to the absolute value of the rotating angle from the reference position of the rotating wheel. A code pattern, a light source provided to face the code pattern, and a photodetector provided with the light source for detecting light emitted from the light source and changed by the code pattern. There is.

Further, a rotation angle calculating means for calculating the rotation angle absolute value based on the output of the photodetector may be included.

Further, a rotation abnormality detecting means for detecting rotation abnormality of the bearing based on the output of the light detecting element may be included.

[0013]

In the first bearing with rotation angle detector according to the present invention, the grating pattern is provided on the rotating wheel side of the bearing, and the light source and the light detecting element are provided so as to face the grating pattern.
When the rotating wheel of the bearing rotates, the output of the light detection element periodically changes by the number of times corresponding to the rotation angle. Therefore, the rotation angle of the rotating wheel can be detected from the number of periodical changes in the output of the light detection element.

Further, since it can be detected digitally as described above, it is hardly affected by electrical noise, and since it can be detected without contact, the contact portion is not worn. Therefore, it has few failures and a long life. Further, since the rotation angle detector is directly provided on the bearing, even if it is provided, for example, at the joint portion of an articulated robot, the rotation angle detector does not hit an obstacle as in the conventional case, and it is safe and has a good external shape. .

Further, in the second bearing with rotation angle detector according to the present invention, the light reflection state on the rotating wheel side of the bearing changes according to the absolute value of the rotating angle from the reference position of the rotating wheel. Since the code pattern is provided and the light source and the light detection element are provided so as to face the code pattern, the absolute value of the rotation angle can be detected from the output of the light detection element. Further, like the first bearing with a rotation angle detector, it has few failures, has a long life, has a good external appearance, and is safe.

[0016]

【Example】

[Embodiment 1] FIG. 1 is a sectional view showing the structure of a bearing 25 with a rotation angle detector according to an embodiment of the present invention, FIG. 2 (a) is a sectional view taken along the line AA 'of FIG. 1, and FIG. ) Is an enlarged view of a C portion of FIG. 2A, FIG. 3A is a sectional view taken along line BB ′ of FIG.
3B is an enlarged view of the optical head 5 of FIG. 3A, FIG. 4 is a sectional view taken along the line D-D 'of FIG. 2B, and EE' of FIG. 3B.
It is a partially broken sectional view including a line section.

In the figure, this bearing 2 with a rotation angle detector is shown.
Reference numeral 5 denotes an outer ring 1 and an inner ring 2 that rotate coaxially via a ball 3, a lattice pattern 4 provided on one end surface of the outer ring 1, an optical head 5 provided opposite to the lattice pattern 4, An annular support member 6 for fixing the head 5 to the end portion of the inner ring 2. The lattice pattern 4 and the optical head 5 rotate while the outer ring 1 and the inner ring 2 rotate relative to each other while maintaining a constant spacing d _A.

As shown in FIGS. 2 and 4, the lattice pattern 4 has a predetermined angular pitch θ _P [where θ _P is the angle (rad) viewed from the rotation center O]. ], The dark portions 4a (portions having a low light reflectance) and the bright portions 4b (portions having a high light reflectance) are alternately provided in an annular shape. Therefore, in the lattice pattern 4, the light reflectance changes in the rotation direction at a constant angular pitch θ _P.

On the other hand, in the optical head 5, as shown in FIGS. 3 and 4, two sets of the light emitting diode and the photodiode LED1, PD1; LED2, PD2 are fixed to the fixing member 5.
It is fixed with a. Each set of light emitting diode LED
The light emitted from the LED 1 and the LED 2 is reflected by the lattice pattern 4 and enters the corresponding photodiodes PD1 and PD2. Also, the two light emitting diodes LE
The two light spots S1 and S2 generated on the grating pattern 4 by the light emitted from D1 and LED2 are displaced from each other by θ _P / 4 in the rotation direction.

When the outer ring 1 and the inner ring 2 rotate relative to each other, however, the light spots S1 and S2 due to the light emitted from the light emitting diodes LED1 and LED2 form dark portions 4a of the lattice pattern 4.
Further, the intensity of reflected light to the photodiodes PD1 and PD2 changes periodically while moving orthogonally to the bright portion 4b.
Here, when the radii of the light spots S1 and S2 are appropriately set, the reflected light intensity to the photodiodes PD1 and PD2 changes in a sine wave shape, and the output signals v ₁ and v ₂ of the photodiodes PD1 and PD2 are as shown in FIG. (a), the sine wave Ksin phase-shifted theta _P / 4 from each other (2πθ /
θ _P ), K cos (2πθ / θ _P ).

[0021] If the mobile light spot S1, S2 is preceded by light spots S1 moves in the direction of arrow b shown in FIG. 2 (b), the output signal v ₁ of the phase than the output signal v ₂ theta _P /
Go forward by 4. On the contrary, if the light spots S1 and S2 move in the direction of arrow B and the light spot S2 moves in advance, the phase of the output signal v ₂ leads the output signal v ₁ by θ _P / 4. Therefore, it calculates the rotation angle θ and the rotational angular speed ω by counting the wave number of the output signal v _1, v _2, it is possible to detect the rotational direction by detecting the phase difference between the output signal v _1, v ₂ .

FIG. 5 is a block diagram showing the configuration of the rotation angle calculation circuit 7 for calculating the rotation angle θ from the output signals v ₁ and v _{2 of the} photodiodes PD1 and PD2. The rotation angle calculation circuit 7 includes two comparators Comp1 and Co.
mp2 and arithmetic processing circuit 8 are included. Comparator Com
p1 and Comp2 are photodiodes PD1 and PD2.
Of the output signals v ₁ and v ₂ are converted into rectangular wave signals V ₁ and V ₂ having a duty ratio of 50% as shown in FIGS. The arithmetic processing circuit 8 calculates the rotation angle θ with a resolution of θ _P / 4 from the number of rising and falling times and the phase difference of the rectangular wave signals V ₁ and V ₂ . The rotation angle θ is converted into a predetermined electric signal, and, for example, the arm 3 of the articulated robot is
It is used to control the operations of 1, 32.

FIG. 7 shows the construction of a rotation abnormality detecting circuit 9 for detecting rotation abnormality of the rotation angle detector bearing 25 from the output signals v ₁ and v _{2 of the} photodiodes PD1 and PD2 of the rotation angle detector bearing 25. It is a block diagram.

First, the principle of the circuit 9 will be described.
It For example, if an excessive load is applied in the axial direction of the bearing 25,
Or an excessive moment is applied to the shaft to rotate the bearing 25.
When the rolling abnormality occurs, the grid pattern shown in FIG. 1 and FIG.
Distance d between lens 4 and optical head 5 _AIs out of the normal range
Oversized or undersized. Interval d_AIs out of the normal range
And the output signal v of the photodiodes PD1 and PD2₁，
v₂The amplitude K of is out of the normal range. That is, in FIG.
As shown, generally the spacing d_AIf becomes too small, the amplitude K becomes too large.
It becomes large and the distance d_AIf becomes too large, the amplitude K becomes too small.
It Therefore, the output signal v₁, V₂Amplitude K is normal
The rotation of the bearing 25 is detected by detecting that it is out of the enclosure.
A motion abnormality can be detected.

Next, the rotation abnormality detection circuit 9 will be specifically described. The rotation abnormality detection circuit 9 includes a fundamental wave amplitude detection circuit 10 and a comparator 11. The fundamental wave amplitude detection circuit 10 outputs the output signal v of the photodiodes PD1 and PD2.
Upon receiving ₁ and v ₂ , the amplitude K thereof is detected and output. The comparator 11 receives the amplitude K from the fundamental wave amplitude detection circuit 10, outputs an excessive amplitude signal φ ₁ when the amplitude K is larger than the upper limit value of the normal range, and when the amplitude value K is smaller than the lower limit value of the normal range. Outputs an under-amplitude signal φ ₂ and causes the arms 31 and 32 of the articulated robot to stop urgently, for example.

FIG. 9 shows the rotation abnormality detection circuit 9 shown in FIG.
3 is a block diagram showing the configuration of the fundamental wave amplitude detection circuit 10. FIG.
It The fundamental wave amplitude detection circuit 10 includes square circuits 12 and 13
And an adder 14. The squaring circuit 12 outputs the output signal v
₁= Ksin (2πθ / θ_P) Squared. Square circuit 1
3 is the output signal v₂= Kcos (2πθ / θ_P) Squared
To do. The adder 14 outputs the outputs v of the squaring circuits 12 and 13.₁ ²，
v₂ ²And add v₁ ²+ V ₂ ²= K²[Sin²(2πθ /
θ_P) + Cos²(2πθ / θ_P)] = K²Output
It

In the fundamental wave amplitude detection circuit 10,
Since erasing rotation angle theta by computing the sum of squares of the output signal v _1, v _2, regardless of the rotation angle theta, i.e. the output signal v _1, with or without rotation of the bearing 25 v
It is possible to detect the squared value K ² of the _second amplitude.

When the fundamental wave amplitude detection circuit 10 is used, the comparator 11 in FIG. 7 outputs the signals φ ₁ and φ ₂ when the square value K ^{2 of the} amplitude is out of the normal range.

FIG. 10 shows the rotation abnormality detection circuit 9 shown in FIG.
Block diagram showing another configuration of the fundamental wave amplitude detection circuit 10 of FIG.
Is. This fundamental wave amplitude detection circuit 10 is a sample hole
The gate circuit 14 and the zero-cross detection circuit 15 are included. zero
The cross detection circuit 15 outputs the output signal v₂The instantaneous value of
Zero cross point detection signal φ ₃
Is output. The sample hold circuit 14 is a zero cross
Point detection signal φ₃In response to the output signal v₁Instantaneous value of
That is, the amplitude value K) is held and output.

FIG. 11 is a block diagram showing the configuration of another rotation abnormality detecting circuit 16. For example ball 3 of bearing 25
When the ball is damaged, the ball 3 does not rotate smoothly, and the rotation abnormality of the bearing 25 occurs. In this case, the distance d _A between the grating pattern 4 and the optical head 5 changes many times during one rotation of the bearing 25, and the photodiodes PD1 and PD
As shown in FIG. 12, the output signals v ₁ and v ₂ of _{No. 2} are obtained by superimposing harmonics on the fundamental wave. Therefore, by separating the harmonic component from the output signals v ₁ and v ₂ and detecting that the amplitude k of the harmonic component is out of the normal range,
Abnormal rotation of the bearing 25 can be detected.

Next, the rotation abnormality detection circuit 16 will be specifically described. The rotation abnormality detection circuit 16 includes a harmonic amplitude detection circuit 17 and a comparator 18. The harmonic amplitude detection circuit 17 separates the harmonic components from the output signals v ₁ and v ₂ ,
The amplitude k of the harmonic component is detected and output. Comparator 18
Receives the amplitude k from the harmonic amplitude detection circuit 17,
If exceeds the upper limit of the normal range, an excessive amplitude signal φ ₄ is output, and the operation of the arms 31 and 32 of the articulated robot is emergency stopped.

In this embodiment, since the rotation angle θ of the bearing 25 can be detected in a non-contact manner, the contact portion is not worn unlike the conventional rotation angle detector 36 using a variable resistor. Therefore, it has a long life and few failures.

Further, since the rotation angle θ is digitally detected by counting the periodical changes of the output signals v ₁ and v ₂ of the photodiodes PD1 and PD2, the rotation angle is determined based on the electric resistance value of the variable resistor. Compared to the conventional method in which θ is detected in analog, it is less susceptible to electrical noise.

Further, the grating pattern 4 and the optical head 5
Since the rotation angle detector including is incorporated in the bearing 25, even when it is provided in the joint part 33 of the articulated robot, for example,
Unlike the conventional case, the rotation angle detector 36 does not hit an obstacle, is safe, and has a good external shape.

Further, if the rotation abnormality detection circuits 9 and 16 are provided, the rotation abnormality of the bearing 25 can be detected and the operation of the arms 31 and 32 of the articulated robot can be stopped urgently, thus improving safety.

The grid pattern 4 may be formed by any method, but if high resolution is not required, a seal or the like having slits at a predetermined angular pitch θ _P is formed on the end surface of the outer ring 1. Good to stick. Further, when high resolution is required, the end face of the outer ring 1 may be chemically etched or laser-marked for direct patterning. Further, when a higher resolution is required, it is preferable to provide a radial transmission type grating also on the optical head 5 side. The signal S / N ratio is improved.

Further, in the rotation angle calculation circuit 7 shown in FIG. 5, the output signals v ₁ of the photodiodes PD1 and PD2,
Although v ₂ was directly converted into rectangular wave signals V ₁ and V ₂ by the comparators Comp 1 and Comp ₂ , output signals v ₁ and v 2 were obtained.
_{If 2} is phase-divided by a well-known output interpolation circuit and converted into many AC signals with smaller phase difference and then converted into a rectangular wave signal, the rotation angle θ can be detected with higher resolution.

In this embodiment, the lattice pattern 4 is provided on the outer ring 1 side and the optical head 5 is provided on the inner ring 2 side.
Conversely, the lattice pattern 4 may be provided on the inner ring 2 side and the optical head 5 may be provided on the outer ring 1 side. The light emitting diodes LED1, LED2 and the photodiode PD1, of the optical head 5
It is advisable to provide the lead wire of PD2 on the side where it is easy to handle.

Although the two light emitting diodes LED1 and LED2 are individually provided in this embodiment, only one light emitting diode LED1 may be provided. However, in this case, it is necessary to arrange the light emitting diode LED1 and the photodiodes PD1 and PD2 so that the two photodiodes PD1 and PD2 receive the light emitted from the light emitting diode LED1 and reflected by the lattice pattern 4 evenly.

[Embodiment 2] FIG. 13 (a) is a front view showing the structure of a bearing 26 with a rotation angle detector according to another embodiment of the present invention, and FIG. 13 (b) is a section F- of FIG. 13 (a). It is a F'line sectional drawing. In the bearing 26 with the rotation angle detector,
The lattice pattern 4 and the optical head 5 are provided so as to face the outer peripheral surface of the inner ring 2 and the inner peripheral surface of the outer ring 1 (in the figure, the lattice pattern 4 is provided on the inner ring 2 side, and the optical head 5 is the outer ring 1).
It is provided on the side). The other structure is the same as that of the bearing 25 with the rotation angle detector shown in the first embodiment, and the description thereof is omitted.

In addition, an excessive load is applied in the radial direction of the bearing 26, an excessive moment is applied to the shaft,
If the ball 3 is damaged or the rotation abnormality of the bearing 26 occurs, the gap d _R between the grating pattern 4 and the optical head 5 fluctuates. Therefore, the rotation abnormality detection circuits 9 and 16 shown in the first embodiment detect the rotation abnormality. Can be detected.

[Third Embodiment] FIG. 14 is a partially omitted development view showing the structure of a code pattern 19 of a bearing with a rotation angle detector according to still another embodiment of the present invention. This code pattern 19 is provided on one rotation surface of the outer ring 1 or the inner ring 2 over a rotation angle Nθ _P , and has M rows and N columns (where M and N are positive positive numbers), and is a bit segment B.
_mn (where m is a positive number from 1 to M, n is 0 to N-
It is a positive number up to 1. ) Is divided into. The N bit sections B _mn arranged in the row direction (rotational direction) form a bit section row Cm, and the M bit sections B _mn arranged in the column direction form a bit section column Rn.

Each bit division B_mnThe light reflectance
Therefore, a binary signal (“0” or “1”) is written.
It M bit sections included in one bit section string Rn
Minute B _n~ B_mnM binary signals written in
A number code, whose binary code is the bit
The column number n of the sorting section Rn is shown. Bit for example
Bit division B in division row R1₁₁Only "1" is written
And other bit classification B_{twenty one}~ B_M1"0" is written in
Bit classification B₁₁~ B_MM binary signals written in
The binary code "00 ... 001" is constructed, and the binary code
The column “00 ... 001” represents the column number 1.

Further, in this bearing with rotation angle detector, M sets of light emitting diodes LED1 to LEDM and photodiodes PD1 and P1 corresponding to the bit division rows C1 to CM are provided.
When DM (not shown) is provided so as to face the code pattern 19 and the outer ring 1 or the inner ring 2 is at the reference position, the light spots S1 to SM generated by the light emitted from the light emitting diodes LED1 to LEDM are bit division strings. They are arranged in a line at the center of R0. Further, when the outer ring 1 or the inner ring 2 is rotated from the reference position by a certain angle θ, the light spots S1 to SM are arranged in a row on the bit segment row Rn corresponding to the rotation angle θ. The other structure is the same as that of the bearing 25 or 26 with the rotation angle detector shown in the first or second embodiment, and the description thereof is omitted.

When the outer ring 1 or the inner ring 2 is rotated from the reference position by a certain rotation angle θ, the light spots S1 to S1.
The SM moves onto the bit segment row Rn corresponding to the rotation angle θ, and the reflected light having the intensity corresponding to the bit segment row Rn enters the light receiving elements PD1 to PDM. Therefore, the binary code is obtained from the outputs of the light receiving elements PD1 to PDM, the binary code is decoded to obtain the column number n, and the column number n is multiplied by the angular pitch θ _P to obtain the rotation angle θ = nθ _P. You can

FIG. 15 shows photodiodes PD1 and PDM.
3 is a block diagram illustrating the configuration of a rotation angle calculation circuit 20 that calculates a rotation angle θ from the reference position based on the output of FIG. The rotation angle calculation circuit 20 includes M comparators Com.
It includes p1 to CompM, a decoder 21, and an arithmetic processing circuit 22. The comparators Comp1 to CompM are photodiodes P that receive the reflected light from the bit division string Rn.
Receiving the output signal v ₁ to v _M of D1～PDM, into a binary signal V ₁ ~V _M "0" or "1". Decoder 21 obtains the column number n of the bit segment sequence Rn decodes the M binary signal V ₁ ~V _M. Arithmetic processing circuit 22
Calculates the rotation angle θ by multiplying the column number n by the angular pitch θ _P.

In this embodiment, since the absolute value of the rotation angle θ from the reference position of the bearing can be obtained, the bearing 25 used in the joint part 33 of the articulated robot is the bearing 25 shown in the first or second embodiment. , 26 is preferable.

In this embodiment, each bit division string R
Although the column number n of n is encoded in the binary code, the column number is not limited to the binary code, and the column number n may be encoded in the binary coded decimal code, the gray code, or the remainder code code. Further, the rotation abnormality detection circuits 9 and 16 may be provided.

[0049]

As described above, in the first bearing with rotation angle detector according to the present invention, the grating pattern is provided on the rotating wheel side of the bearing, and the light source and the photodetector element are opposed to the grating pattern. Since it is provided, it is possible to detect the rotation angle of the rotating wheel from the number of periodical changes in the output of the light detection element due to rotation.

Further, since it can be detected digitally as described above, it is hardly affected by electric noise, and since it can be detected without contact, the contact portion is not worn. Therefore, it has few failures and a long life. Further, since the rotation angle detector is directly provided on the bearing, even if it is provided, for example, at the joint portion of an articulated robot, the rotation angle detector does not hit an obstacle as in the conventional case, and it is safe and has a good external shape. .

Further, in the second bearing with rotation angle detector of the present invention, the light reflection state on the rotating wheel side of the bearing changes according to the absolute value of the rotating angle from the reference position of the rotating wheel. Since the code pattern is provided and the light source and the light detection element are provided so as to face the code pattern, the absolute value of the rotation angle can be detected from the output of the light detection element. Also,
Similar to the first bearing with a rotation angle detector, it has few failures, has a long life, has a good external appearance, and is safe.

[Brief description of drawings]

FIG. 1 is a sectional view showing a structure of a bearing with a rotation angle detector according to an embodiment of the present invention.

2A is a sectional view taken along the line AA ′ in FIG. 1, and FIG. 2B is an enlarged view of a C portion in FIG.

3A is a sectional view taken along the line BB ′ of FIG. 1, and FIG. 3B is an enlarged view of the optical head 5 of FIG.

4 is a sectional view taken along line DD ′ of FIG. 2 (b) and FIG. 3 (b).
FIG. 6 is a partially cutaway cross-sectional view including a cross section taken along line EE ′ of FIG.

5 is a block diagram showing a configuration of a rotation angle calculation circuit for calculating a rotation angle θ from output signals v ₁ and v _{2 of} photodiodes PD1 and PD2 of the bearing with rotation angle detector shown in FIG.

6A is a waveform diagram showing output signals v ₁ and v ₂ of photodiodes PD1 and PD2, and FIGS. 6B and 6C are obtained from the output signals v ₁ and v ₂ shown in FIG. 6A, respectively. FIG. 7 is a waveform diagram showing rectangular wave signals V ₁ and V ₂ .

7 is a block diagram showing a configuration of a rotation abnormality detection circuit for detecting rotation abnormality of the bearing with rotation angle detector shown in FIG.

8 is a waveform diagram for explaining the operation of the rotation abnormality detection circuit shown in FIG.

9 is a block diagram showing a configuration of a fundamental wave amplitude detection circuit of the rotation abnormality detection circuit shown in FIG.

10 is a block diagram showing another configuration of the fundamental wave amplitude detection circuit of the rotation abnormality detection circuit shown in FIG.

FIG. 11 is a block diagram showing the configuration of another rotation abnormality detection circuit that detects rotation abnormality of the bearing with rotation angle detector shown in FIG. 1.

12 is a waveform diagram for explaining the operation of the rotation abnormality detection circuit shown in FIG.

13A is a front view showing the structure of a bearing with a rotation angle detector according to another embodiment of the present invention, and FIG. 13B is a sectional view taken along line FF ′ of FIG. 13A.

FIG. 14 is a partially omitted development view showing a configuration of a code pattern of a bearing with a rotation angle detector according to still another embodiment of the present invention.

FIG. 15 is a block diagram showing a configuration of a rotation angle calculation circuit that calculates a rotation angle θ from a reference position from outputs of photodiodes PD1 to PDM.

FIG. 16A is a diagram illustrating a usage state of a conventional rotation angle detector, a partially cutaway front view showing a joint part of an articulated robot, and FIG. 16B is a part of FIG. It is the fractured side view.

[Explanation of symbols]

 1 Outer ring 2 Inner ring 4 Lattice pattern 7,20 Rotation angle calculation circuit 9,16 Rotation abnormality detection circuit 19 Code pattern 25,26 Bearing with rotation angle detector LED Light emitting diode PD Photodiode S Light spot

Claims (8)

[Claims] 1. A grating pattern provided on a rotating wheel side of a bearing, a light source provided so as to face the grating pattern, and light provided together with the light source, which is emitted from the light source and changed by the grating pattern. A bearing with a rotation angle detector, comprising a photodetection element for detecting. 2. The grating pattern, the light reflectance of which changes at a predetermined angular pitch, and the light source and the light detecting element are provided on the other ring of the bearing. 1. A bearing with a rotation angle detector according to 1. 3. The rotation angle detector according to claim 1, wherein a plurality of the light detection elements are provided, and the direction of each light receiving surface is deviated from the rotation direction of the lattice pattern. bearing. 4. The bearing with a rotation angle detector according to claim 3, wherein a plurality of the light sources are provided corresponding to the light detection elements. 5. The rotation angle according to claim 1, further comprising rotation angle calculation means for calculating the rotation angle based on a periodic change in the output of the photodetector. Bearing with detector. 6. A code pattern, which is provided on the rotating wheel side of the bearing and whose light reflection state changes according to the absolute value of the rotation angle from the reference position of the rotating wheel, and a code pattern which is provided so as to face the code pattern. A bearing with a rotation angle detector, comprising: a light source; and a light detection element that is provided together with the light source and detects light emitted from the light source and changed by the code pattern. 7. The bearing with a rotation angle detector according to claim 6, further comprising rotation angle calculation means for calculating the rotation angle absolute value based on the output of the photodetection element. 8. The bearing with a rotation angle detector according to claim 5, further comprising rotation abnormality detection means for detecting rotation abnormality of the bearing based on an output of the light detection element.