JPS6226401B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an eccentricity measuring device for a rotation speed detector used when controlling the rotation speed of a motor, etc.
More specifically, the present invention relates to an eccentricity measuring device for a rotational speed detector that can electrically measure eccentricity between a rotational shaft and a detection signal transmitter that occurs when the rotational speed detector is assembled.

Conventionally, a rotation speed detector has a disk constituting a detection signal generating section that has slits arranged concentrically and equally spaced perpendicularly to the rotation axis of a rotating body, and a pair of photocouplers are mounted on both sides of the disk. The number of rotations of the rotating body is detected by using a slit to intermittent the light from the light emitting body of the photocoupler as the rotating body rotates, and by detecting the number of pulses output from the photoreceptor of the photocoupler. .

In this case, due to the bending of the rotation axis, the eccentricity of the detection signal generation section having a slit, the mutual relationship between the detection signal generation section and the rotation axis being non-orthogonal, etc.
Even though the rotational speed of the rotating shaft is at a reference value, the rotational speed of the rotating shaft may be detected to be incorrect based on the output of the rotational speed detector.

For this reason, it is important to assemble the rotation shaft and the detection signal generation section with a slit, and the center hole of the detection signal generation section with a slit has the same diameter as the rotation shaft and is at a height concentric with the outer periphery of the detection signal generation section. They were assembled by precision machining, fitting the rotating shaft, and optically aligning the center of the shaft using a microscope. However, when using the former method, the higher the precision required, the more expensive it becomes, and when using the latter method, there are drawbacks such as poor work efficiency, resulting in less production and higher prices. Ta.

The present invention has been made in view of the above, and is a rotation speed detection device that can measure the amount of eccentricity and the direction of eccentricity between a rotation shaft and a detection signal generating section of the rotation speed detector using a simple method. The purpose of the present invention is to provide a device for measuring the eccentricity of a rotation speed detector, and the eccentricity measurement device for a rotation speed detector detects the rotation axis generated during assembly of the rotation speed detector and the detection signal generation part of the rotation speed detector. The eccentricity of the rotation speed detector is measured, and the rotation speed detector is assembled while making corrections based on the results, thereby making it possible to obtain a highly accurate rotation speed detector.

The feature of the device of the present invention is that it uses a phase-locked loop (hereinafter referred to as PLL) that detects the amount of eccentricity and the direction of eccentricity between the detection signal generator of the rotation speed detector used to control the rotation speed of a motor, etc. and the rotating shaft. It is characterized by electrical measurement using a circuit (referred to as a circuit).

The present invention will be explained below using examples.

FIG. 1 is a block diagram of an embodiment to which the apparatus of the present invention is applied. This embodiment is an example in which the rotational speed is detected optically.

1 is a motor whose rotational speed is detected, and 2 is a rotating shaft of the motor 1 or an extension shaft directly connected to the rotating shaft of the motor 1 (hereinafter simply referred to as a rotating shaft).
As shown in FIG. 2, the rotating shaft 2 has a plurality of slits 3 arranged concentrically at equal intervals for detecting the number of rotations.
A disk 5 serving as a rotation signal detecting section having one slit 4 for an angle reference signal is fixed inside any one of the plurality of slits 3. A light emitting element 6 faces one surface of the disc 5 and emits light through the slits 3 and 4; a phototransistor 7 faces the other face of the disc 5 and receives light from the light emitting element 6 through the slit 3; , the light emitting element 6 through the slit 4
The disc 5, the light emitting element 6, and the light receiving elements 7 and 8 constitute a rotation speed detector. The output of the light receiving element 7 is outputted to a Schmitt circuit 10 through a waveform shaping circuit 9, and the output of the Schmitt circuit 10 is sent to a phase converter 11.
and voltage controlled oscillator 12 and low pass filter 1
Input to the PLL circuit consisting of 2-1. The output of the PLL circuit is passed through an amplifier 13 to adders 14 and 15.
input to one of the input terminals.

On the other hand, the output of the phototransistor 8 is the differential circuit 1
6 to the sine wave oscillator 17. The sine wave oscillator 17 is triggered by the output of the differentiating circuit 16 and generates a sine wave output synchronized with the output of the phototransistor 8. The output of the sine wave oscillator 17 is used as the other input of the adder 15, and is also used as the other input of the adder 14 through a phase shift circuit 18 which shifts the phase of the input by π/2 radians and outputs it. Adder 14
The output of the adder 15 is applied as the Y-axis input of the oscilloscope 19, and the output of the adder 15 is applied as the X-axis input of the oscilloscope 19.

Now, due to the rotation of the rotating shaft 2, the disk 5 rotates,
The phototransistor 7 has a rotational speed X corresponding to the rotational speed.
The number of pulses equal to the number of slits 4 is generated (this signal is referred to as a rotation speed detection signal). The phototransistor 8 also generates a number of pulses equal to the number of rotations (this signal will be referred to as an angle detection signal).

The output pulse of the phototransistor 7 is waveform-shaped by the waveform shaping circuit 9, inputted to the PLL circuit through the Schmitt circuit 10, and then outputted to the voltage controlled oscillator 12.
The oscillation frequency of is phase-locked to the rotation speed detection signal obtained by the phototransistor 7. Therefore,
For example, if there is no eccentricity in the assembly of the rotating shaft 2 and the disk 5, the rotational speed detection signal from the phototransistor 7 is a signal with a constant frequency, and the control voltage of the voltage controlled oscillator 12 is It does not change. The control voltage of this voltage controlled oscillator 12 is directly added to a sine wave signal synchronized with the angle detection signal from the phototransistor 8 in an adder 15, and is also a signal obtained by shifting the phase of the sine wave signal by π/2 radians. and the outputs of adders 14 and 15 are added to the Y-axis and X-axis of the oscilloscope 19, respectively.
Since the voltage is applied to the axis, a circular sysage figure as shown by the broken line in FIG. 3 is drawn on the cathode ray tube of the oscilloscope 19.

On the other hand, if eccentricity or the like exists between the rotating shaft 2 and the disk 5, the rotational speed detection signal from the phototransistor 7 becomes a frequency-modulated output. That is, if eccentricity occurs in the disk 5, the light emitting element 6
Since the positions of the phototransistor 7 and the phototransistor 7 are fixed, the disk 5 on the phototransistor 7
The circumferential velocity of changes. For this reason, for example, when the slit 3 of the disk 5 on the phototransistor 7 is deviated from the phototransistor 7 toward the central axis side, the pulse interval becomes long because the circumferential speed is slow.
Further, when the slit 3 is deviated outward from the phototransistor, the pulse interval becomes short because the circumferential speed is high. Therefore, during one rotation of the disk 5, the pulse interval becomes longer, becomes normal, or becomes shorter. As a result, the pulse signal becomes a frequency modulated output. When the rotational speed detection signal from the phototransistor 7 is subjected to frequency modulation, the control voltage of the voltage controlled oscillator 12 changes. That is, the control voltage of the voltage controlled oscillator 12 changes depending on the degree of frequency modulation of the rotation speed detection signal.
The amount of eccentricity between the rotating shaft 2 and the disk 5 is detected as the amount of change in this control voltage, and the direction of eccentricity is detected as the direction of change in the control voltage.

Now, as mentioned above, the control voltage of the voltage controlled oscillator 12 is directly added to the output of the sine wave oscillator 17 and the output obtained by shifting the output of the sine wave oscillator 17 by π/2 radians in the adders 14 and 15, respectively. Applied to the Y and X axes of the cilloscope. Therefore, the control voltage of the voltage controlled oscillator 12 described above is a DC voltage, and the level of the control voltage changes depending on the amount of eccentricity and the direction of eccentricity. Therefore, the Lissage figure drawn on the cathode ray tube of the oscilloscope 19 is a circular figure as shown by the solid line in Figure 3, but this Lissage figure and the circular Lissage figure shown by the broken line in Figure 3 are different. The location is different.
In this case, the eccentric direction of the circular Lissage figure shown by the solid line in FIG. 3 from the Lissage figure shown by the broken line in FIG. 3 corresponds to the eccentric direction of the disk 5, and the eccentricity between the Lissage figures is This corresponds to the amount of eccentricity between the rotating shaft 2 and the disc 5.

Therefore, it is possible to correct the eccentricity between the rotating shaft 2 and the disk 5 while observing the resizage figure drawn on the oscilloscope 19. This correction is easy, unlike in the conventional case, and can be done in one operation. Adjustment between the rotating shaft and the rotational speed detector can be easily completed.

The same applies to the case of correcting the bending of the rotating shaft or the oblique mounting of the disc.

Although the above-mentioned embodiment shows what is displayed on an oscilloscope, the values of the X-axis and Y-axis may be displayed digitally.

As explained above, according to the device of the present invention, the output of the rotation speed detection circuit that converts the rotation speed of the rotation shaft of the rotating body into a pulse train signal is input to the PLL circuit, and the output of the PLL circuit is used to determine the rotation speed of the rotation shaft and the rotation speed. By measuring the amount and direction of eccentricity between the detection signal transmitting section of the detection circuit and the eccentricity direction, it is possible to easily correct the eccentricity between the detection signal transmitting section of the rotation speed detection circuit and the rotating shaft in one operation. , the number of man-hours for assembling the rotation speed detector can be reduced and accuracy can be improved, and there is no need to make the parts more accurate than necessary, making it possible to produce a high-precision, low-cost rotation speed detector.

In addition, it can be applied to the production of high-precision rotation speed detectors required for motors of tape decks, record players, etc., in particular, to improve work efficiency.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of one embodiment of the apparatus of the present invention.
FIG. 2 is a diagram of a disk as a rotation signal detection section. Third
The figure is a diagram for explaining the operation of an embodiment to which the device of the present invention is applied. 1...Motor, 2...Rotating shaft, 3 and 4...
Slit, 5... Disk, 6... Light emitting element, 7 and 8... Phototransistor, 9... Waveform shaping circuit, 10... Schmidt circuit, 11... Phase comparator, 12... Voltage controlled oscillator, 12 -1...Low pass filter, 13...Amplifier, 14 and 15
... Adder, 16 ... Differentiation circuit, 17 ... Sine wave oscillator, 18 ... Phase shift circuit, 19 ... Oscilloscope.

Claims (1)

[Claims] 1. A rotation speed detector that is fixed to the rotation shaft of a rotating body and converts the rotation speed of the rotation shaft into a pulse train signal and also generates an angle reference signal for the rotation body, and a rotation speed detector that is fixed when the output of the rotation speed detector is constant. sends out a voltage output,
a phase-locked loop circuit that outputs the amount and direction of voltage change when the output of the rotation speed detector changes; a sine wave oscillator that outputs a sine wave synchronized with the angle reference signal from the rotation speed detector; an adder for adding the output from the phase-locked loop circuit and the output from the sine wave oscillator; and an adder for transferring the output from the phase-locked loop circuit and the output from the sine wave oscillator by π/2 radians and outputting the resultant. An eccentricity measuring device for a rotation speed detector, comprising an adder that adds the outputs from the transfer circuit, and measures an eccentricity amount and an eccentric direction based on the outputs from the two adders. .