JP2000180212A - Angular position detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an angular position detector of small-size and low price without spoiling detecting accuracy by serving a slit both for detecting angular change and displaying a reference angle position. SOLUTION: A slit 102a indicating a reference angle position is constituted to be in the same row as the other slits 101 and formed into a larger hole than the slit 101. Accompaning the large hole of the slit 102a, the quantity of light passing through the slit 102a becomes larger than the quantity of light passing through the slit 101. A slit plate 10a is constituted so that the quantity of light increases at the reference angle position, but even if it is constituted to decrease the quantity of light of the slit 102a by changing setting of the reference level of a waveform shaping part, similar effect is generated. Hereat, photoelectrically detecting slits are made basically non-transmitting parts and two sorts of slits are formed on the non-transmitting parts, hence three sorts of parts in all have different transmittance, and the angle and the reference angle position can be detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an angular position detector for detecting a rotation angle of a rotating body, and more particularly to a reference angular position detection of a rotating body.

[0002]

2. Description of the Related Art There are various methods for detecting the angular position of a rotating object. A rotary encoder method is used in which a slit is formed or added to a rotating body, and the slit is optically detected to detect a rotation angle. It is widely used because it is the simplest and can be constructed at low cost.

FIG. 8 shows the structure of a slit plate 10 used in a conventional rotary encoder system. The slit plate 10 is made of a material that does not transmit light, and slits 101 are arranged near the circumference of the slit plate 10 so as to be at equal intervals, and light can be transmitted through the slit 101 portion. I have. Further, as an index indicating the reference angle position, only one slit 102 is formed at a position independent of the row of slits 101 per rotation.

FIG. 9 shows an entire configuration of a conventional angular position detector. The slit plate 10 is fixed to the rotating shaft 11 and rotates integrally with the rotating shaft 11. In order to detect the rotation angle, the light emitting element 2 is sandwiched by the slit plate 10 in the thickness direction.
A set of a first detection system including 1 and a light receiving element 22 and a set of a second detection system including a light emitting element 31 and a light receiving element 32 are arranged corresponding to the slit 101. The rotating shaft 1
Slit 1 of slit plate 10 which rotates according to rotation of 1
The light 201 that has exited the light emitting element 21 changes intermittently by the slit 101 and reaches the light receiving element 22 corresponding to 01. The signal PA generated according to the intensity of the received light is level-shaped by the waveform shaping unit 23 to be a binary level, and is output as the signal A.

The same applies to the combination of the light emitting element 31 and the light receiving element 32.
It changes intermittently by 1 and reaches the light receiving element 32. The signal PB generated according to the intensity of the received light is level-shaped by the waveform shaping unit 33 to be a binary level, and is output as the signal B.

In the conventional angular position detector shown in FIG. 9, a set of a light emitting element 41 and a light receiving element 42 is provided corresponding to the position of the slit 102 similarly to the set of the light emitting element 21 and the light receiving element 22. The light that has exited the light emitting element 41 is a slit 102
Changes intermittently and reaches the light receiving element 42. The signal PZ generated according to the intensity of the received light is level-shaped by the waveform shaping unit 23 to be a binary level, and is output as the signal Z.

FIG. 10 shows examples of signals A, B and Z when the rotation speed is constant. The signal A is “H” when the light reaches the light receiving element 22 through the transmission part of the slit 101.
When the light has not arrived, the cycle T changes to "L".

The signal B also changes in the same manner as the signal A, but the position of the signal B is adjusted so that the signal A is out of phase by a quarter of the period T. The position adjustment is performed by moving the position of the set of the light emitting element 31 and the light receiving element 32, and adjusts the relative position with respect to the position of the set of the light emitting element 21 and the light receiving element 22. By adjusting the relationship between the signal A and the signal B so as to be shifted by T / 4, the rotation direction of the rotating shaft 11 can be detected. Assuming that a signal having the phase relationship shown in FIG. 10A is detected when the rotation axis is clockwise, the phase relationship between signal A and signal B is obtained as shown in FIG. 10B when the rotation axis is counterclockwise. Is obtained.

As described above, the rotation angle, that is, the angle change can be calculated by counting the change of the signal A or the signal B or the change of both of them by the counting means (not shown). Further, the rotational direction of the rotating shaft can be detected from the relative relationship between the levels of the signals A and B.

However, the absolute angular position of the rotating shaft 11 cannot be detected only by the signal A and the signal B. In order to detect the absolute angular position, the rotation angle detector of FIG. 9 detects the reference angular position signal signal Z in the same manner as the detection of the signal A and the signal B based on the slit 102. Signal Z is slit 1
"H" when light reaches the light receiving element 42 after passing through the transmission portion 02, and "L" when light does not reach the light receiving element 42.
Becomes Since the signal Z becomes "H" only once per one rotation of the rotating shaft 11, the absolute angle of the rotating shaft 11 can be detected by initializing the output of the counting means (not shown) with the signal Z.

[0011]

As described above, in order to detect the absolute angle of the rotating shaft, it is necessary to set a reference angular position. It is necessary to form the slit 102 indicating the reference angle position at a position different from the row of the slits 101 indicating the slits, which hinders a reduction in the size of the slit plate.
Further, a detection system for obtaining the signal Z, that is, the reference angle position,
It is necessary to prepare another system separately from the signal A and signal B detection systems. For this reason, there is a problem that three systems must be prepared and the structure cannot be reduced.

Moreover, the detection system of the reference angle position detects a signal only once per rotation of the rotating shaft 11, and no signal is detected during the other period. Therefore, the efficiency of the apparatus is very low.

For this reason, the conventional angular position detector has a problem that the size of the apparatus is hindered as a whole, resulting in an inefficient configuration and a high cost.

[0014]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and is characterized in that a slit 101 for detecting a change in angle also serves to display a reference angle position. . Furthermore, in the configuration of the present invention, by generating a non-zero signal at the reference angle position, it is possible to configure a small and inexpensive angle position detector without impairing the detection accuracy of the reference angle position. .

[0015]

FIG. 1 shows the structure of a slit plate 10a of an angular position detector according to a first embodiment of the present invention. The slit 102a representing the reference angle position is configured in the same row as the other slits 101, and is characterized by a hole larger than the slit 101. Slit 10
As the hole 2a is large, the amount of light passing through the slit 102a is larger than the amount of light passing through the slit 101.

FIG. 2 shows the overall configuration of the rotation angle detector according to the present embodiment. The same components as those in the conventional embodiment of FIG. 9 are denoted by the same reference numerals, and the description is omitted.

The signal PA from the light receiving element 22 is input to the waveform shaping section 43a. The signal PA is generated by the waveform shaping unit 43a by comparing the signal PA with a reference level V1 corresponding to the amount of light passing through the slit 101, and the signal Z is compared with a reference level V2 corresponding to the amount of light passing through the slit 102a. appear.

Here, the reference level V2 corresponding to the amount of light passing through the slit 102a is higher than the reference level V1 corresponding to the amount of light passing through the slit 101.

The configuration of the slit plate 10a shown in FIG. 1 increases the light amount at the reference angle position. However, by changing the setting of the reference level V2 of the waveform shaping section, the light amount of the slit 102a decreases. The same effect can be obtained.

In the description of the present embodiment, the signal Z is generated on the signal A side, but the signal Z can be generated from the signal B side.

Therefore, in the present embodiment, the slit for photoelectric detection is basically a non-transmissive part, and two kinds of slits are formed on the non-transmissive part, so that three kinds of parts have different transmittances, and And detecting the reference angle position.

FIG. 4 shows a slit plate 10b according to a second embodiment of the present invention, in which the reference angle position is detected by controlling the amount of transmitted light by changing the transparency of the slit.
It is characterized in that only the slit 102b at the reference angular position in the slit row engraved on the slit plate 10b is covered with a material 103 having a transmittance different from that of the slit plate 10b.

FIG. 5 shows a cross-sectional configuration near the slit according to the present embodiment. Since the slit plate 10b is transparent,
Since a different transmittance, for example, a slightly opaque material 103 is not disposed in the slit 101 portion, light is transmitted as it is, and light is blocked in a non-transparent portion. on the other hand,
A slightly opaque material 103 is disposed in the slit 102b indicating the reference angle position, and the amount of transmitted light is reduced as compared with the slit 101. Since the amount of detection light is smaller at the reference angle position corresponding to the slit 102b than at the slit 101b due to the effect of the slightly opaque material 103, the reference angle position signal Z can be detected based on the change.

Therefore, in the present embodiment, a portion corresponding to the position of the slit for performing photoelectric detection is formed as a non-transmitting portion and two types of transmitting portions, and by utilizing the fact that the three types of portions have different transmittances, It is characterized by detecting an angle and a reference angle position.

FIG. 6 shows a cross section of a slit plate 10c according to a third embodiment of the present invention.
The reference angle position is detected by changing the state of the surface state c. The feature of this embodiment is that the material itself of the slit plate 10c is made transparent so that the light transmission state is controlled according to the surface formation state.

There are three types of formation states on the surface of the slit plate 10c. The surface corresponding to the slit 101 is formed flat in the first formation state, and light is transmitted best. The portion of the slit 102c indicating the reference angle position corresponds to the second formation state and has a slightly rough surface, and the amount of transmitted light is smaller than that of the slit 101. Portions other than the slit correspond to the third formation state, are formed with a very rough surface, and have the smallest amount of transmitted light.

The slit 102 is formed by three kinds of surface conditions.
At the reference angle position corresponding to c, the detected light amount is smaller than that at the slit 101, so that the reference angle position signal Z can be detected based on the change.

Therefore, the present embodiment is characterized in that three types of surface states are formed at portions corresponding to the positions of the slit portions for performing photoelectric detection so as to have three types of transmittance, and the angle and the reference angle position are detected. And

FIG. 7 shows a slit plate 10d having a sectional structure according to a fourth embodiment of the present invention.
The reference angle position is detected by changing the formation state and thickness of the surface d. The feature of the present embodiment is that the material itself of the slit plate 10d is transparent, and the amount of transmitted light is controlled by combining the state of surface formation and the change in thickness.

The slit plate 10d has three types of structures. The portion corresponding to the slit 101 is the first structure, has a flat surface and a small thickness, and has a transmittance T1 at a portion where light is transmitted best. The portion of the slit 102d indicating the reference angle position corresponds to the second structure, and the surface is flat but the thickness is slightly thicker than the portion of the slit 101, and the amount of transmitted light is smaller than the transmittance of the first structure. It has a small second transmittance T2. The portion other than the slit corresponds to the third structure, has a very rough surface and a large thickness, and has the smallest transmittance T3 as the amount of transmitted light. That is, the slit plate 10d has three portions having a relationship of T1>T2> T3.

Since the amount of light detected at the reference angle position corresponding to the slit 102d is smaller than that at the slit 101 due to the effects of the three types of structures, the reference angle position signal Z can be detected based on the change.

Therefore, the present embodiment is characterized in that a portion corresponding to the position of the slit for performing photoelectric detection is provided with three types of transmittance by combining the thickness and the surface state, and the angle and the reference angle position are detected. .

In the embodiments described so far, a configuration is adopted in which information on the reference angular position can be reliably detected. Hitherto, for example, as disclosed in Japanese Patent Application Laid-Open No. 9-152357, a configuration has been proposed in which a signal is detected at a reference angle position by missing a signal. However, when the signal of the reference angle position is set to zero, information on the angle position near the reference angle position is lost, and there is a disadvantage that the detection accuracy is deteriorated. In the present invention, a corresponding signal is detected even at the reference angle position, so that the disadvantages of the conventional proposal can be overcome.

[0034]

As described above, in the angular position detector of the present invention, the angle detection slit is formed in the rotating body and the rotation angle is detected by optically detecting the angle detection slit. By adding information on the angular position to the angle detection slit, two systems can be used instead of the three systems conventionally required. Since the detection system for the reference angle position is also a part that constantly detects a change in angle, it is possible to eliminate waste in the configuration of the apparatus.

The size of the slit plate can be reduced because the angle detection slit row and the reference angle position slit indicating the absolute position are formed in the same row, and the entire angle position detector can be made small, so that the cost can be reduced. it can.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a slit plate 10a according to a first embodiment of the present invention;

FIG. 2 is a diagram illustrating a configuration of an angular position detector according to the first embodiment.

FIG. 3 is a diagram showing a method for generating signals A and Z according to the first embodiment;

FIG. 4 is a diagram showing a configuration of a slit plate 10b according to a second embodiment of the present invention;

FIG. 5 is a diagram showing a cross-sectional configuration of a slit plate 10b according to a second embodiment of the present invention;

FIG. 6 is a diagram illustrating a cross-sectional configuration of a slit plate 10c according to a third embodiment of the present invention.

FIG. 7 is a diagram illustrating a cross-sectional configuration of a slit plate 10d according to a fourth embodiment of the present invention.

FIG. 8 is a diagram showing a configuration of a slit plate 10 used in a conventional angular position detector;

FIG. 9 is a diagram showing a configuration of a conventional angular position detector.

FIG. 10 is a diagram showing a relationship among signals A, B, and Z.

[Explanation of symbols]

10, 10a, 10b, 10c, 10d slit plate, 11 rotation axis, 21, 31, 41 light emitting element, 22, 32, 42 light receiving element, 23, 33, 43 waveform shaping section, 22, 32, 42 light receiving element, 101 Slits, 102, 102a, 102b, 102c, 102d
Angle reference position slit

Claims (10)

[Claims] 1. An angular position detector for forming an angle detecting slit in a rotating body and detecting an angle of the rotating body by photoelectrically detecting the slit, a signal indicating a reference angular position in a region of the slit. An angle position detector which forms a portion for generating an angle and detects an angle and a reference angle position from a signal of the slit. 2. The area of the slit where photoelectric detection is performed is 3
2. The angular position detector according to claim 1, wherein the angular position detector is formed of a portion having different kinds of transmittance. 3. The angular position detector according to claim 2, wherein the portions having the three transmittances correspond to a transmitting portion and a non-transmitting portion of the slit and the reference angle position portion. 4. The angular position detector according to claim 3, wherein said three kinds of transmittances are created by changing the size of said slit hole. 5. A portion having the three types of transmittance by forming the slit in the rotating body made of a transparent material and providing a portion of a material having a transmittance different from that of the rotating body in the material. 4. The angular position detector according to claim 3, wherein: 6. The angular position detector according to claim 3, wherein the portions having the three kinds of transmittances are realized by changing the surface state of the rotating body. 7. The angular position detector according to claim 3, wherein the portions having the three transmittances are realized by making the surface state and the thickness of the rotating body different. 8. The magnitude of the signal indicating the reference angle position is:
8. The angular position detector according to claim 1, wherein a signal other than the reference angular position is smaller than a signal from the slit and is not zero. 9. The magnitude of the signal indicating the reference angle position is:
The angular position detector according to claim 1, wherein a signal is larger than a signal from the slit other than the reference angular position. 10. An angular position detector for periodically generating a plurality of phase angle signals in accordance with the rotation of a rotator and detecting an angle of the rotator based on the angle signal, wherein the rotator has a reference angle. An angular position detector, which generates a signal of a different level when in a position and in a position other than a reference angular position.