JP2000088603A - Apparatus for detecting rotation angle of rotator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely detect the rotation angle of a rotator by presetting its rotation angle from a reference position, roughly detecting it by a rough rotation angle detecting means, and detecting that a reflected beam from a reflection mirror at the rotator comes to the center of a light receptor. SOLUTION: A slide 13 is slid, a guide pin 16 is tightly fixed at a desired angle from a reference position 17, and a potentiometer 6 is set to stop a motor 5 at a desired angle. When the motor 5 is started to rotate at approximately desired angle position with the potentiometer 6, the optical axis of a reflected beam light 12 is within a fixed range from the centers of light receiving surfaces 10a, 10b, and the light quantity is at or over a fixed value. When a comparator 27 detects that the output of an adder circuit 26 is at a fixed level V or more, a control signal comes to a switch control circuit via a gate circuit 28 to actuate a switch circuit 21 to switch a motor control system. A detection signal generator circuit 25 takes a max. output value of the adder circuit 26 and controls to stop the motor 5 when a zero-cross point on the output of a differential amplifier 23 is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to robots, machine tools,
The present invention relates to a rotation angle detection device for a rotating body used in various inspection test devices and the like.

[0002]

2. Description of the Related Art For example, in a robot or a machine tool, a technique in which a swing arm is swung by a motor is used. The rotation angle of the swing arm, which is such a rotating body, is detected using a rotary potentiometer and a rotary optical encoder. The operation of stopping the swing arm is performed by obtaining a control signal corresponding to a predetermined angle to be stopped based on the detection output and controlling the motor based on the control signal.

[0003]

In many cases, the rotation of the rotating body is performed at a high speed. In this case, the potentiometer and the optical encoder as the detecting means increase the moment of inertia by their weight. Therefore, it is difficult to stop at a predetermined angle quickly. On the other hand, if an attempt is made to reduce the weight in order to reduce the moment of inertia, the configuration must be simplified, and the detection accuracy naturally decreases,
A highly accurate rotation angle detection device cannot be obtained.

Accordingly, an object of the present invention is to provide a rotation angle detecting device for a rotating body which has high accuracy and good response speed.

[0005]

In order to achieve the above object, the present invention provides a coarse rotation angle detecting means for coarsely detecting a rotation angle of a rotating body rotating with respect to a fixed portion from a reference position; A reflecting mirror arranged on the rotating body side, a light source arranged on the fixed part side for irradiating the light beam toward the reflecting mirror, and the fixed part side for receiving the reflected beam light from the reflecting mirror A light-receiving portion having a divided light-receiving surface disposed therein, and the light-receiving amount of each of the light-receiving surfaces is electrically detected after the rotation angle is roughly detected by the coarse rotation angle detecting means. Detecting means for detecting that the reflected light beam has reached the center of the divided light receiving portion; and rotating the rotator from a reference position based on the position of the reflected light beam detected by the detecting means. Set the angle in advance And a setting means for, those related to the rotation angle detection apparatus configurations the rotary body so as to detect the rotation angle from the reference position of the rotating body.
According to a second aspect of the present invention, the setting unit is configured such that the light source and the light receiving unit are arranged on a sliding body slidably arranged on the fixing unit and fixed at a desired position. It is desirable.

[0006]

The rotation angle of the rotator is first set in advance by a setting means from the reference position of the rotator, and is then roughly detected by the coarse rotation angle detection means, and then the reflection angle is set on the rotator side. It is precisely detected by detecting that the reflected light beam from the mirror reaches the center of the light receiving section.

[0007]

Next, an embodiment of the present invention will be described with reference to FIGS.

In FIG. 1, reference numeral 1 denotes a jig mounting portion 2 at the tip.
And a rotating body comprising a swing arm rotatably attached to the fixed part 4 by the rotating shaft 3. This rotating body 1
Is rotated by a motor 5. Reference numeral 6 denotes a potentiometer which constitutes a coarse rotation angle detecting means for roughly detecting the rotation angle of the rotating body 1 from a reference position. Since the potentiometer 6 only needs to detect the rotation angle roughly, it may have a simple configuration and a small moment of inertia. Next, a configuration for densely detecting the rotation angle will be described. This forms a notch 7 cut out to the rotation center axis of the rotary shaft 3, a reflecting mirror 8 is arranged in the notch 7, and a light source 9
And the light receiving unit 10 are opposed to each other. Specifically, the light source 9 is a laser diode, and its light beam 1
1 is directed toward the reflecting mirror 8 and its reflected beam light 12
Reach the light receiving unit 10. The light source 9 and the light receiving unit 10 are arranged on the sliding body 13 at a predetermined interval. The detection of the dense rotation angle is detected based on the position of the reflected beam 12 as described later in detail.

The setting means 14 has the following configuration. A groove 15 is formed in the sliding body 13, and a guide pin 16 attached to the fixing portion 4 is engaged with the groove 15.
Is formed in an arc shape so that the sliding body 13 is slid concentrically with the rotary shaft 3. The guide pins 16 are made of screws so that the sliding body 13 can be fixed at a desired position. The setting means 14 is a means for setting a close rotation angle. As shown in FIG.
1 and 2 of the angle formed by the respective optical axes of the reflected beam light 12
The angle formed by a straight line, that is, the straight line 17 perpendicular to the reflecting mirror 8 and the extension line 19 of the reference position 18 is set in advance as a predetermined angle.

The motor 5 is operated by a drive circuit 20. The drive circuit 20 is connected to the output of an amplifier 22 constituting the coarse rotation angle detecting means via one terminal 21a of the switch circuit 21. The output of the potentiometer 6 directly connected to the motor 5 is supplied to the input side of the amplifier 22. The coarse rotation angle of the motor 5 is detected within the range of the resolution of the potentiometer 6, and the rotation operation is stopped with the accuracy.

Next, a detecting means for densely detecting the rotation angle will be described. As shown in FIG. 2, the light receiving unit 10 includes a pair of light receiving surfaces 10a and 10b divided into two in the front and rear in the same direction as the rotation direction of the reflecting mirror 8. Light receiving surface 10
Reference numerals a and b denote photodiodes, and the amount of received light is electrically detected. Light receiving surface 10
Outputs a and 10b are connected to respective input terminals of the differential amplifier 23. The reflected light beam 12 has a circular shape as shown in FIG. 3, and is condensed near the light receiving unit 10 by a condensing lens 24 arranged in front of the light source 9. A detection signal generation circuit 25 is connected to an output side of the differential amplifier 23, and an output side of the detection signal generation circuit 24 is connected to the other terminal 21 b of the switch circuit 21. On the other hand, the outputs of the light receiving surfaces 10a and 10b are
Is added as shown in FIG.
7, a comparison with a constant level V is made. When the output of the comparator 27 is higher than the level V as shown in FIG. 4B, an H-level signal is obtained and becomes the control input of the gate circuit 28 and is supplied to the switch control circuit 29. When the control input signal is supplied, the switch control circuit 29 switches so that the switch circuit 21 connects the detection signal generation circuit 25 and the drive circuit 20. The output of the addition circuit 26 is supplied to the detection signal generation circuit 25,
The zero cross point P of the output signal of the differential amplifier 23 shown in FIG. 4C is obtained in correspondence with the maximum value shown by A. This zero cross point P is the reflected light beam 1 shown in FIG. 3A.
This corresponds to a state where the optical axis No. 2 reaches the middle between the light receiving surfaces 10a and 10b.

The operation of the embodiment of the present invention described above is as follows.

First, the setting means 14 sets the rotation angle. This slides the slide 13 to move the reference position 17
And a guide pin 16 is tightened and fixed at that position. On the other hand, the set value of the potentiometer 6 is set so that the motor 5 stops at the desired angle.

Next, the motor 5 is operated based on the start command to rotate the rotating body 1. The motor 5 is rotated to a coarse position with respect to a desired angle by coarse rotation angle detecting means including a potentiometer 6 or the like. This position is within the detection range of the optical detection means. 3B and 3C, the optical axis of the reflected light beam 12 is deviated from the center of the light receiving surfaces 10a and 10b by a fixed amount, and the reflected light beam 12 has a fixed level as shown in FIG. 4A. V or more. Therefore, as shown in FIG. 4A, the output of the adding circuit 26 is detected by the comparator 27 to be equal to or higher than the predetermined level V, and the control signal shown in FIG. Activate 21. This switch circuit 21
Is switched so that the control system thereof is controlled by the optical detection means. The detection signal generation circuit 25 takes a maximum value of the output of the addition circuit 26 and simultaneously outputs a control signal for stopping the motor 5 when the zero cross point P of the output of the differential amplifier 23 is obtained as shown in FIG. 4C. Will be sent. Actually, there is some inertia so that it converges toward the zero cross point P,
The convergence operation is performed quickly because the moment of inertia is small. The reason why the moment of inertia can be reduced is that the configuration of the potentiometer 6 is simplified, and that the extra mirror is only added to the rotating part, and the increase due to this is substantially negligible. Then, as shown in FIG. 3A, the optical axis of the reflected beam light 12 is
It is located at the center of a, 10b and is stable there. That is, the rotating body 1 is stopped at a predetermined desired angular position. The detection accuracy can be significantly improved because not only the distance between the light receiving surfaces 10a and 10b can be reduced, but also the distance from the reflecting mirror 8 to the light receiving unit 10 can be increased.

When the rotating body 1 is applied to, for example, a test apparatus for a magnetic head for a hard disk drive, a magnetic head is attached to the tip of the rotating body 1 so that a test disk rotating at a high speed can be moved between inner and outer tracks. It reciprocates many times at high speed. The inner and outer track positions must be set to extremely small values corresponding to the track pitch of the hard disk. The hard disk device itself detects the track position based on the servo signal of each track, but the test disk cannot use the servo signal. In such an example of application to a test apparatus, an optically precise angle detection can be performed using a thin light beam as in the above-described embodiment, so that a track position with a small track pitch can be detected. At the same time, since the moment of inertia of the entire structure is small, it can be immediately stopped at a desired position.

[0016]

FIG. 5 shows another embodiment of the present invention. this is,
The light source 9A and the light receiving unit 10A are mounted on the first sliding body 13A as a first pair, and the light source 9B and the light receiving unit 10B are mounted on the second sliding body 13B as a second pair. Independently slidable from the reference position 17 so that it can be arbitrarily set at a predetermined different angle. It can be pivoted within each angle range. Further, the stop position can be set in two stages from the reference position.

Further, the first light receiving section 10 is made common with a light source.
A, You may arrange | position the 2nd light receiving part 10B similarly to the above.

Further, even if the reflecting mirror 8 is not disposed on the center axis of the rotating shaft 3, the light beam 11 from the light source 9 is reflected as the reflected light beam 12 to reach the light receiving section 10. I just need.

When the stop position of the rotating body 1 is equal to or more than two rotations, the gate circuit 28 and the like are operated only after the detection output of the adding circuit 26 in the detecting means is obtained a desired number of times to enable optical detection. do it. Further, a detecting means for detecting that the rotation of the motor 5 has reached a desired number is provided, for example, on the rotating shaft 3, and the output of the adding circuit 25 activates the gate circuit 28 and the like based on the detection output of this detecting means. You may.

[0020]

According to the first aspect of the present invention, as a first effect, the rotation angle of the rotating body is detected roughly by the coarse rotation angle detection means and then accurately by the optical detection means. Because of this, the structure of the coarse rotation angle detecting means can be simplified, and the moment of inertia is reduced as a whole by simply adding a reflector which can substantially ignore the mass, so that quick and accurate detection is possible. As a second effect, it is possible to increase the distance between the reflecting mirror and the light receiving unit and detect the rotation angle precisely. According to the second aspect, the rotation angle of the rotating body can be arbitrarily changed by fixing the position of the sliding body to a desired position.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a rotation angle detection device for a rotating body according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing in detail a detecting means and a setting means of a rotation angle detecting device of a rotating body in one embodiment of the present invention.

FIG. 3 is an explanatory view showing in principle a state of a light receiving beam in the light receiving unit of FIG. 2;

FIG. 4 is a waveform chart showing the operation of the detection means of FIG.

FIG. 5 is an explanatory view showing another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rotating body 3 Rotating axis 4 Fixed part 5 Motor 6 Potentiometer 8 Reflecting mirror 9 Light source 10 Light receiving part 13 Sliding body 14 Setting means 17 Reference position

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2F065 AA39 BB25 CC00 DD02 DD03 FF19 FF23 GG04 HH03 JJ05 JJ23 KK01 LL15 MM15 MM26 PP13 QQ25 QQ28 TT02 UU03 2F103 BA32 BA37 BA43 CA03 DA13 EA17 EB02 EB15 EB16 EB16 EB15

Claims (2)

[Claims] 1. A rough rotation angle detecting means for roughly detecting a rotation angle of a rotating body that rotates with respect to a fixed portion from a reference position; a reflecting mirror arranged on the rotating body side; A light source disposed on the fixed unit side to irradiate the light beam, and a light receiving unit having a divided light receiving surface disposed on the fixed unit side for receiving the reflected light beam from the reflecting mirror; After the rotation angle is roughly detected by the coarse rotation angle detection means, the light reception amount of each of the light receiving surfaces is electrically detected,
Detecting means for detecting that the reflected light beam has reached the center of the divided light receiving surface when both are equal to each other; and the rotator based on the position of the reflected light light detected by the detecting means. Setting means for presetting a rotation angle from the reference position of the rotation body, wherein the rotation angle of the rotation body from the reference position is detected. 2. The light source and the light receiving unit are arranged on a sliding body slidably disposed on the fixing unit and fixed on a desired position. The rotation angle detection device for a rotating body according to claim 1.