JPH04256823A - Motor-fitter measuring apparatus - Google Patents

Abstract

PURPOSE:To make it possible to measure motor jitter readily and highly accu rately by detecting the position where the reflected light from a slant mirror provided on the rotary shaft of a motor to be measured is received. CONSTITUTION:Laser light 3 emitted from a laser 1 is reflected from a slant mirror 9 fixed on the rotary shaft of a motor to be measured 6 through a lens system 5. The reflected laser light 15 is received with a CCD line sensor 19 provided on a flat plate 11. When the laser light 15 is received with the cell at the center of the sensor 19, a signal S is transmitted from the central cell and inputted into a laser control part. When the signal S is detected in the laser control part, the laser 1 is once turned OFF. After the elapse of a specified time, i.e., at a time when the next laser light 15 should be cast in to the central cell of the sensor when there is no jitter in the rotation of the motor 6, the laser 1 is instantaneously turned ON.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor jitter measuring device for measuring motor jitter during one rotation with high precision.

0002

[Prior Art] Conventionally, motor jitter measuring devices include:
The following were used. That is,
As shown in FIG. 3, the light source is a He-Ne gas laser 5.
A laser beam 52 emitted from the motor 55 passes through a lens system 53 and is reflected by an inclined mirror 59 fixedly arranged on a rotation axis 57 of a motor 55 to be measured. At this time, the axis of the rotation shaft 57 coincides with the optical path of the laser beam 52, and the reflective surface 59a of the tilted mirror 59 is inclined at 45 degrees with respect to the axis of the rotation shaft 57. A motor 55 is driven by a well-known motor drive circuit (not shown) into a rotating shaft 57 and a tilting mirror 5 fixedly arranged on the rotating shaft 57.
When 9 is rotated in the direction of arrow A, the reflected laser beam 60 reflected by the tilted mirror 59 rotates in a circle in the direction of arrow B. Photodiodes 61a and 61b are arranged at two points on the circular locus of this reflected laser light 60, and receive the reflected laser light 60. Photodiode 61a, 6
1b is connected to a well-known measurement circuit (not shown),
The passage time of the reflected laser beam 60 from when the photodiode 61a receives the reflected laser beam 60 to when the photodiode 61b receives the reflected laser beam 60 is measured.

Next, the motor 55 to be measured is rotated a certain amount in the direction of arrow C, or the photodiode 6 is
1a, 61b or both are connected to the rotating shaft 5 of the motor 55.
7 in the direction of arrow D, and similarly to the above, the passage time for the reflected laser beam 60 to pass between the two photodiodes 61a and 61b is measured. Such measurements are repeated, and the time taken to pass between the two photodiodes 61a and 61b is measured for each direction during one rotation.

[0004] Then, the variation ΔT in the transit time for the reflected light 60 to pass between the two photodiodes 61a and 61b
Using the angle of view θ, which is the angle between the two photodiodes 61a and 61b from the rotation axis 57 of the motor 55 to be measured, the motor 55 is measured by θ/ΔT.
It is possible to find the fluctuation in the rotational speed of. Therefore, by the above measurements, the rotational speed fluctuation of this motor 55,
That is, the jitter of the motor 55 can be determined.

[0005]

However, when such a measurement method is used, the viewing angle θ between the two photodiodes 61a and 61b from the rotating shaft 57 of the motor 55 to be measured must be kept constant, or It is necessary to accurately determine the angle of view. In particular, when measuring motor jitter with high precision, it is necessary to maintain this angle of view θ with the same degree of accuracy as the measurement target accuracy, or to determine this angle of view θ with the same degree of accuracy. It was very difficult to do so.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a motor jitter measuring device that can measure motor jitter extremely easily and with high precision.

[0007]

[Means for Solving the Problems] In order to achieve this object, the motor jitter measuring device of the present invention includes a light source that emits a light beam, and a motor jitter measuring device that is arranged on the rotation axis of a motor to be measured, and that uses a light beam emitted from the light source. an inclined mirror that reflects the light at a predetermined angle with respect to the axis of the rotating shaft; and a tilted mirror that is rotated by the motor so as to be provided on a trajectory drawn by the reflected light reflected by the inclined mirror;
It has a light receiving means for receiving the reflected light, a moving means for moving the light receiving means along the trajectory, and a position detecting means for detecting a position where the reflected light is received by the light receiving means.

[0008]

[Operation] In the present invention having the above configuration, the light beam emitted from the light source is reflected at a predetermined angle with respect to the axis of the rotation axis by the tilted mirror placed on the rotation axis of the motor to be measured. The light is received by the light receiving means. The light receiving means is moved by the moving means. If there is no jitter in the rotation of the motor to be measured, the reflected light will be received at a predetermined position of the light receiving means, but if there is jitter, the reflected light will be received at a position other than the predetermined position. Therefore, the position detection means detects at which position of the light receiving means the reflected light is received,
Find the motor rotation jitter.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a motor jitter measuring device embodying the present invention will be described below with reference to the drawings.

As shown in FIG. 1, a laser 1 is a semiconductor laser which is a light source in this embodiment, and is connected to a laser control section 20 shown in FIG. 2, and outputs a laser beam 3. A lens system 5 is arranged on the optical path of the laser beam 3 output from the laser 1. In front of it, a motor 6 to be measured (hereinafter referred to as a measurement motor) is arranged so that the axis of the rotation shaft 7 of the measurement motor 6 and the optical path of the laser beam 3 coincide with each other. Further, an inclined mirror 9 having a reflective surface 9a at a predetermined angle with respect to the axis of the rotating shaft 7 is fixedly arranged on the rotating shaft 7. On the other hand, behind the laser 1, a flat plate 1 is connected to a motor (hereinafter referred to as a reference motor) 10 whose jitter amount is already known.
1 is placed. The rotation shaft 13 of the reference motor 10
is located on the same axis as the rotation shaft 7 of the measurement motor 6, and rotates in the opposite direction to the rotation direction of the rotation shaft 7 of the measurement motor 6.

On the other hand, on the flat plate 11, as shown by the two-dot chain line in FIG. As shown in FIG. 2, a CCD line sensor 19 having a plurality of cells 17 (the number is omitted and shown as five in FIG. 2) is provided in the section. This CCD line sensor 19 is connected to the reference motor 10.
rotates integrally with the flat plate 11 as the rotating shaft 13 rotates,
Each cell 17 is connected to a control circuit 20 as shown in FIG. In addition, each cell 1 of the CCD line sensor 19
The pitch between 7 is 0.1 mm. In this embodiment, the flat plate 11 is located at a position where the laser beam 3 is focused on the surface of the CCD line sensor 19 by the action of the lens system 5, and where the locus drawn by the reflected laser beam 15 reflected by the inclined mirror 9 is a radius. They are placed in a 160mm circle. Furthermore, both the measurement motor 6 and the reference motor 10 are arranged with a placement error on the order of 10 μm.

The control circuit 20 is composed of a statistical processing calculation section 21, a display section 23, and a laser control section 25. The statistical processing calculation unit 21 detects in which cell 17 of the CCD line sensor 19 the reflected laser beam 15 incident on the CCD line sensor 19 is received a predetermined number of times, and statistically processes the result to calculate the measurement motor 6. Find jitter. A display unit 23 is connected to the statistical processing calculation unit 21, and displays the amount of jitter determined by the statistical processing calculation unit 21 on a display (not shown). In addition, the laser control section 2
5 is connected to the central cell 17a of the CCD line sensor 19 and the statistical processing calculation unit 21, and controls the driving of the laser 1 according to the output of each cell 17 of the CCD line sensor 19.

Next, an example of a method for measuring motor jitter using the motor jitter measuring device configured as described above will be explained.

First, as shown in FIG. 1, the rotating shaft 7 of the measuring motor 6 is rotated in the direction of arrow X by a known motor drive circuit (not shown). Then, the rotation shaft 13 of the reference motor 10 is rotated in the direction of arrow Y, which is the opposite direction to the rotation direction of the measurement motor 6, by a well-known motor drive circuit (not shown). At this time, the accuracy of the rotation speed of this reference motor 10 is set to be 10-5 or less. Next, the laser control section 25 shown in FIG. 2 outputs the laser beam 3 from the laser 1 and causes it to illuminate continuously. The output laser beam 3 passes through a lens system 5,
The reflected laser beam 15 is reflected by an inclined mirror 9 fixedly arranged on the rotation axis 7 of the measurement motor 6, and the reflected laser beam 15 is received by a CCD line sensor 19 provided on the flat plate 11. When this reflected laser light 15 is received by the center cell 17a of the CCD line sensor 19, a signal S is emitted from the center cell 17a and input to the laser control section 25. When the laser control unit 25 detects this signal S, the laser 1 is turned off once, and after a certain period of time has elapsed, that is, when there is no jitter in the rotation of the measurement motor 6, the reflected laser beam 15 is
The laser 1 is turned on momentarily at the time when the laser is supposed to enter the center cell 17a of the CD line sensor 19.

Here, if there is no jitter in the rotation of the measuring motor 6, the reflected laser beam 15 produced by the momentarily turned on laser beam 3 reflected by the tilted mirror 9 is received by the central cell 17a of the CCD line sensor 19. Ru. Then, the signal S is again emitted from this center cell 17a, and the same operation as described above is performed. Also, if there is jitter in the rotation of the measurement motor 6, other cells 17 of the CCD line sensor 19
The light is received by If the jitter is too large at this time, the CCD
If it comes off the line sensor 19, an error will occur. Then, the laser control section 25 causes the laser 1 to be continuously turned on again, and the same operation as described above is performed. These operations are performed a predetermined number of times, and the statistical processing calculation unit 25 statistically processes which cell 17 of the CCD line sensor 19 receives the light, and the result is obtained as the jitter of the measurement motor 6 and displayed on the display unit 23 (not shown). Show it as a number on the display.

In this embodiment, the radius of the circular trajectory drawn by the reflected laser beam 15 reflected by the inclined mirror 9 on the flat plate 11 is 160 mm, and each cell 1 of the CCD line sensor 19 is
The pitch between 7 is 0.1 mm. Measuring motor 6 to 3
0000 r. p. m. The reference motor 10, which rotates the flat plate 11, is rotated in the direction of the arrow Y, which is opposite to the rotational direction of the measuring motor 6, at a rotation speed of 29970 r.
p. m. When the laser 1 is continuously turned on by the laser control unit 25 by rotating at a rotation speed of
The time interval at which the light enters the center cell 17a is 60/(30000+29970)=2/1999[s
ec]. That is, the reflected laser beam 15 is received by the central cell 17a of the CCD line sensor 19 approximately every 1 ms. Therefore, when the reflected laser beam 15 first enters the center cell 17a of the CCD line sensor 19, the laser controller 25 temporarily turns off the laser 1, and
After s, the laser 1 is turned on for 10 ns. Then, the statistical processing calculation section 21 detects which cell 17 of the CCD line sensor 19 receives the reflected laser light 15 at that time. By performing such measurements a predetermined number of times as described above, the jitter of the measuring motor 6 can be determined. Further, the length of the circumference of the circular locus drawn by the reflected laser beam 15 is approximately 1000 mm, and the CCD line sensor 1
Since the pitch between each cell 17 of 9 is 0.1 mm, the jitter measurement accuracy of the measurement motor 6 is 0.1/10.
00 = 10-4. That is, the jitter of the measuring motor 6 can be easily measured with an accuracy of 10-4.

The present invention is not limited to the embodiments detailed above, and various changes can be made without departing from the spirit thereof.

For example, the light source may be another beam light source such as a He-Ne gas laser, and the arrangement of the light source may be such that the light beam is incident on the rotation axis of the motor to be measured.For example, the light path may be bent by a mirror. It can be freely deformed by guiding it with a single-mode optical fiber. Furthermore, the light receiving means is not limited to a CCD line sensor as long as it can detect the position of the light beam with a predetermined resolution. In addition, instead of guaranteeing the speed accuracy of the reference motor that rotates the light receiving means,
The timing of emitting laser light may be corrected by detecting the rotation angle.

[0019]

[Effect of the invention] As is clear from the detailed description above,
According to the present invention, it is possible to provide a motor jitter measurement device that easily enables highly accurate measurement of motor jitter.

[Brief explanation of the drawing]

FIG. 1 is a perspective view schematically showing a motor jitter measuring device embodying the present invention.

FIG. 2 is a block diagram of a control circuit of a motor jitter measuring device embodying the present invention.

FIG. 3 is a perspective view schematically showing a conventional motor jitter measuring device.

[Explanation of symbols]

1 Laser 6 Measuring motor 7 Rotation axis 9 Tilted mirror 10 Standard motor 19 CCD line sensor 20 Control circuit

Claims (1)

[Claims] 1. A light source that emits a light beam; an inclined mirror that is disposed on the rotation axis of a motor to be measured and that reflects the light beam emitted from the light source at a predetermined angle with respect to the axis of the rotation shaft; The tilting mirror is rotated by the motor to be placed on a trajectory drawn by the reflected light reflected by the tilting mirror, and a light receiving means for receiving the reflected light and the light receiving means are moved along the trajectory. A motor jitter measuring device comprising a moving means and a position detecting means for detecting a position where the reflected light is received by the light receiving means.