JPH04161830A - Evaluation of deflection of rotary shaft of rotary encoder - Google Patents

Abstract

PURPOSE:To evaluate the deflection of a rotary shaft highly accurately by detecting the time difference in generation timings between multiple-phase pulses generated in response to the specified rotational position of a rotary encoder, and detecting the fluctuating amount for every rotation. CONSTITUTION:Pulses in a phase Z, a phase A and a phase B are outputted from light receiving sensors 7a, 7b and 7c, respectively. The Z-phase pulse which is generated by the rotation of a rotary encoder having the multiple-phase output used as the rotation synchronizing signal. In the pulse trains in the phases A and B, the generation timing between the specified pulses in the respective phases generated in response to the specified rotatational positions of a rotary shaft 2 of the encoder is detected for every rotation. The time difference in generation timing for every rotation is detected, and the fluctuation amount of the difference is detected. Thus, the magnitude of the asynchronous component of the deflection of the rotary shaft of the encoder is evaluated. Thus, the deflection of the rotary shaft can be evaluated.

Description

[Detailed description of the invention] [! TECHNICAL FIELD The invention relates to a method for evaluating rotary shaft runout of a rotary encoder by detecting an aperiodic component of the rotary shaft runout of the rotary encoder.

[Conventional technology] Rotary encoders generally use a rotational drive source (motor, etc.)
The rotary encoder is connected to the rotary encoder and the rotating body, and uses pulses generated by the rotary encoder to detect the rotational position (angle) and rotational speed.

In a conventional optical rotary encoder, a slit plate is generally fixed to a rotating shaft supported by a bearing such as a ball bearing, and a light receiving sensor receives the light from a projecting light source placed across the slit plate. There is a lot of trouble. A division pattern is engraved on this slit plate, and when the rotation shaft is rotated, a pulse train corresponding to this division pattern is output from the light receiving sensor, and this pulse train is used to detect the rotation angle and rotation speed of the rotation shaft. Let's do it.

By the way, as mentioned above, the rotating shaft of the rotary encoder is supported by bearings such as ball bearings, so the rotating shaft is subject to periodic vibrations and non-periodic vibrations that occur due to the precision of the bearings. There is a sway.

In addition, even if the rotary encoders are of the same type and type, the axial runout of these rotating shafts is caused by variations in bearing accuracy and assembly accuracy, so it is important to make sure that each rotary encoder is the same.
Even when installed in different conditions, each shaft runout is different.

Therefore, in order to detect the rotational angle and rotational speed of the aforementioned rotating shafts with high precision, it is important to evaluate the axial runout of each rotating shaft with each rotary encoder attached.

As a conventional method for evaluating rotational shaft runout of a rotary encoder, there is a method in which, for example, a non-contact displacement sensor (such as a capacitance type sensor or a vortex type sensor) is attached to the rotary shaft to directly measure the shaft runout.

[Invention tries to solve! lIj! 1] However, in order to directly measure the shaft runout using a non-contact displacement sensor and extract the non-periodic component, it is necessary to use a high-precision sensor because the non-periodic component is extremely small compared to the periodic component. Moreover, an expensive sensor is required. Furthermore, in order to separate and extract the non-periodic component at each rotational position of the rotating shaft, this non-contact sensor must be attached to each rotational position with high precision, which is very time consuming.

This invention solves this drawback, and its purpose is to detect the non-periodic component of rotational shaft runout by detecting the amount of variation for each rotation of the time difference in the generation timing between specific pulses of each phase of the rotary encoder. An object of the present invention is to provide a method for evaluating rotary shaft runout of a rotary encoder, which can easily and highly accurately evaluate the rotary shaft runout of a rotary encoder without using a special sensor.

[t! Means for Solving IPi] In order to solve the above problem, the method for evaluating the rotary shaft runout of a rotary encoder according to the present invention includes By detecting the generation timing between specific pulses of each phase that occur in response to a predetermined rotational position of the rotary encoder's rotating shaft for each rotation, and detecting the amount of variation for each rotation in the time difference between the generation timings. , is characterized in that the magnitude of the non-periodic component of the rotation axis runout of the rotary encoder is evaluated.

[Operation] In the method of evaluating the rotary shaft runout of a rotary encoder according to the present invention, the occurrence between specific pulses that occur corresponding to a predetermined rotational position among the pulse trains of each phase generated by a rotary encoder having multiphase output is Detect timing.

The magnitude of the non-periodic component of the rotation axis runout of the rotary encoder is evaluated by measuring the time difference between the occurrence timings for each rotation and detecting the amount of variation.

[Example] An embodiment of the present invention will be described below with reference to the drawings.

′! FIG. J1 is a schematic diagram showing the structure of an optical rotary encoder to which the present invention is applied, and FIG. 2 is a diagram showing the output state of the optical rotary encoder.

The structure of the rotary encoder is such that a rotating shaft 2 is supported on a main body 1 by a bearing 3 such as a ball bearing, and a rotating slit plate 4 is fixedly attached to the rotating shaft 2. A pattern is engraved on this rotating slit plate 4, and a projecting light source 5 is provided opposite to this rotating slit plate 4.
It receives light and transmits light corresponding to the pattern. On the opposite side of the rotating slit plate 4 from the projecting light source 5, a fixed slit plate 6 is fixedly provided, which has slits 68 to 6C in a multiphase array, and further corresponds to the slits 68 to 6c. Light receiving sensors 7a to 7C are arranged.

The light transmitted through the rotating slit plate 4 during rotation passes through the slits 6a to 6C of each phase of the fixed slit plate 6, and the pattern of light for each phase is detected by the light receiving sensors 7a to 7C. A pulse train corresponding to each phase is transmitted to the light receiving sensors 7a to 7c.
is output from. Using this pulse train, the rotation angle and rotation speed of the rotary shaft 2 are detected, and the evaluation circuit 8 evaluates the rotary shaft runout of the rotary encoder.

As shown in FIG. 2, a Z-phase pulse is output from the light-receiving sensor 7b, an A-phase pulse is output from the light-receiving sensor 7b, and a B-phase pulse is output from the light-receiving sensor 7c. Two-phase pulses generated by the rotation of the rotary encoder with multi-phase output are used as rotation synchronization signals, and are generated corresponding to a predetermined rotational position of the rotary encoder's rotating shaft 2 among the A-phase pulse and B-phase pulse trains. The generation timing between specific pulses of each phase is detected for each rotation, and the time difference Δxi, Δx2 . .DELTA.x3... and the amount of variation thereof (.DELTA.xmax - .DELTA.xmin) are detected to evaluate the magnitude of the non-periodic component of the rotational shaft vibration of the rotary encoder.

Figures 3 to 'M9 are principle diagrams showing the principle of the evaluation method for the rotary shaft runout of this rotary encoder.
The figures and FIGS. 6A and 6B show cases where there is periodic wobbling on the rotating shaft, and FIGS. 7 and 8 show cases where there is aperiodic wobbling on the rotating shaft.

In FIG.'s3, FIG. 5, and FIG. 7, the symbol C indicates the center of rotation of the rotary shaft 2 of the rotary encoder when there is no wobbling on the rotary shaft. On the other hand, the symbol in FIG. 5 indicates the rotation center point when periodic runout occurs in the rotating shaft 2, and the symbol E in FIG. It shows the center of rotation of .

This principle diagram shows a rotary encoder with three-phase output, and as mentioned above, two phases, B phase,
It has a rotating slit plate 4 having an A-phase slit pattern. A light source 5 for projecting light into the slit pattern of each phase.
The light emitted by the light emitted from the fixed slit plate 6 passes through the slits 68 to 6C of the fixed slit plate 6, which are bored corresponding to each phase. This light is detected by light receiving sensors a to 7C corresponding to each phase and outputs a pulse train corresponding to each phase.
Each of the light receiving sensors F a to F C is on the line CF.

As shown in Figure 3, when there is no runout in the rotation axis, the center of rotation is at point C, and the relative positions of the light receiving sensors F-A to F-C and the slit patterns of each phase for Z, B, and A phases. The relationship naturally does not change, so there is no relative time change in the output pulses of each phase. Figure 4 shows the generation timing between specific pulses at a predetermined rotational position of the A phase and B phase at this time. Explain using. ′! In Figure J4, the time required from the rising edge (a) of a specific pulse for the human phase to the rising edge (b) of the corresponding specific pulse for the B phase T++-
Tn is always constant when there is no shaft runout on the rotating shaft.

Further, when there is periodic wobbling in the rotating shaft as shown in FIG. 5, the center of rotation moves periodically from point C to the point. Even in this case, since the light receiving sensors 7a to 7c are on the line CF, the light receiving sensors 7a to 7c are located at the predetermined rotational positions that should originally be detected by the light receiving sensors 7a to 7c, that is, positions shifted from the line DG. 0 which will detect the slit pattern
for example'! In the jSS diagram, the slit pattern of phase A is equal to the angle θ^, and the slit pattern of phase B is equal to the angle θ^.
B minutes are detected before reaching the predetermined rotational position both in terms of distance and time. Also, at this time, the timing at which the A-phase light receiving sensor 7b and the B-phase light receiving sensor 7b receive light from their respective slit patterns is relative to the angle θIN.
There will be a deviation of θB - θ^. In other words, if there is periodic wobbling in the rotation axis, the relative positional relationship between the light receiving sensor faces a to 7C and the slit patterns of each phase will fluctuate periodically compared to when there is no wobbling, and the The output pulses also undergo periodic relative time fluctuations.

At this time, the generation timing between the specific pulses of the A phase and the B phase is from the rising edge (C) of the specific pulse of the A phase to the corresponding B The time T required for the rise (d) of the specific pulse of the phase deviates by a time ΔT1 corresponding to the angle 01 minutes.

That is, TmTn-ΔT1. However, since this shaft runout of the rotating shaft is periodic, CD- remains constant no matter how many times the shaft rotates, and ΔT1 also remains constant.

However, if there is non-periodic wobbling in the rotating shaft as shown in FIG. 7, the center of rotation moves from point C to point E non-periodically. Even in this case, the timing at which the A-phase light receiving sensor 7C and the B-phase light receiving sensor 7b receive light from their respective slit patterns is relatively shifted by an angle of 02, as in the case where there is periodic vibration described above. It turns out.

At this time, the generation timing between the A-phase and B-phase specific pulses corresponds to the rising edge (e) of the A-phase specific pulse, as shown in Figure 8, compared to the case where there is no shaft runout on the rotating shaft. The time T required for the rise (f) of the B-phase specific pulse deviates by a time ΔT2 corresponding to the angle 02 minutes.

That is, TmTn-ΔT2. However, since the shaft runout of this rotating shaft is non-periodic, the distance between CE and the direction of E as seen from C change each time it rotates, and ΔT2 also changes each time. Therefore, the magnitude of the non-periodic component of the 0-rotation shaft runout, which causes T to fluctuate, can be determined by continuously measuring T and determining the time difference Δx1. △x2. The evaluation is performed by detecting Δx3... and detecting the amount of variation thereof (Δxwax−Δxmjn).

Based on FIG. 9, the amount of variation in the time difference in the generation timing between the specific pulses will be explained. In Fig. 9, when a specific pulse of A phase rises (g), a corresponding specific pulse of B phase rises with the shortest time TxTmin (h), and a case where it rises with the longest time T w T wax (i) and find this 'MxzT@ax-Tain. This difference X corresponds to the non-periodic component of the rotary shaft runout, and the rotary shaft runout of the rotary encoder is evaluated by evaluating the magnitude of this difference for each predetermined rotational position.

In this example, the 2-phase, B-phase, and A-phase pulses of the rotary encoder are outputted from a set of light-receiving sensor faces a to 7C corresponding to each phase to evaluate the non-periodic component of the rotation shaft runout. However, this can also be done using two sets of light receiving sensors, in which case the aperiodic component can be determined with higher accuracy.

FIG. 10 shows a principle diagram showing the principle of the evaluation method for rotary encoder rotation axis runout when two sets of light receiving sensors are used. In FIG. 10, one set of light receiving sensors 7a to 7C is shown.
is on the line CF as in the above case, and the other set of light receiving sensors 8a to 8C are on the line C which intersects with the line CF.
It is on I.

The other sets of light-receiving sensors 8a to 8C also output phase pulse trains corresponding to the 2-phase, B-phase, and A-phase, respectively.

When there is non-periodic vibration in the rotating shaft 2 as shown in FIG. 10, when the center of rotation of the rotating shaft 2 moves to E, the light receiving sensors 7a to 7C are on the line CF, and the light receiving sensor 8a-8
Since C is on the line CI, the predetermined rotational position that each light-receiving sensor should detect, that is, the light-receiving sensor 7a~
The slit pattern of each phase is detected at a position shifted from the line EH in the case of the frame C, and the slit pattern of each phase is detected by the light receiving sensors 8a to 8c at a position offset from the line EJ. Note that since the movement of the center of rotation from C to E is actually minute, even if the center of rotation moves to point E, each of the light receiving sensors 7a to 71c and 8a to 8C will detect each phase slit pattern.

Therefore, as described above, in the light receiving sensors 7b and 7c, the A-phase slit pattern and the B-phase slit pattern are shifted to predetermined rotational positions in terms of distance and time by an angle θ^ and an angle θB, respectively. The timing of detecting the slit pattern before and then receiving the slit pattern of each phase is relatively shifted by an angle θ2=θB−〇ﾾ. Therefore, the generation timing between the A-phase and B-phase specific pulses is shifted by a time ΔT2 corresponding to the angle 02 minutes.

Similarly, in the light receiving sensors 8b and 8C, the A phase slit pattern and the B phase slit pattern are set at an angle θ^
1 minute and angle θBl, the detection is delayed from the predetermined rotational position both in terms of distance and time, and the timing of receiving the slit patterns of these phases is also relative to the angle θ3 = θB1 - θ^ There will be a difference of one minute. Furthermore, the generation timing between the A-phase and B-phase specific pulses is also shifted by a time ΔT3 corresponding to the angle 03 minutes.

In this way, when the generation timing between the specific pulses of the A phase and B phase is measured separately using two sets of light receiving sensors, the time difference in the generation timing ΔT2. From ΔT3, the above angle 62. θ3 can be found. Therefore, the direction of axial runout of the rotating shaft 2 can be specified, and the aperiodic component can be measured and evaluated with high precision even for two-dimensional axial runout.

[Effects of the Invention] As described above, the present invention calculates the non-periodic component of the rotary shaft runout of a rotary encoder having multi-phase output by calculating the amount of variation for each rotation in the time difference in the generation timing between specific pulses of each phase. By detecting this, it is possible to easily perform a highly accurate evaluation of the rotary encoder's rotational shaft runout without using a special sensor.

[Brief explanation of the drawing]

Fig. 341 is a schematic diagram showing the structure of an optical rotary encoder to which this invention is applied, Fig. 2 is a diagram showing the output state of the optical rotary encoder, and Figs. 3 and 9 are diagrams showing the rotation axis runout of this rotary encoder. Figures 3 and 4 show the case where there is no runout of the rotating shaft, and Figures 5 and 346 show the case where there is periodic runout of the rotating shaft. , Fig. 7 and Fig. 8 show the case where there is aperiodic vibration in the rotation axis, Fig. 9 is an explanatory diagram explaining the amount of variation in the time difference in the generation timing between specific pulses, and Fig. 10 is FIG. 3 is a principle diagram showing the principle of a method for evaluating rotational shaft runout of a rotary encoder when a set of light receiving sensors is used. In the figure, reference numeral 2 is a rotating shaft, 4 is a rotating slit plate, 5 is a light source for projecting light, 6 is a fixed slit plate, and 7a to 7C are light receiving sensors. Figure 1 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 1θ

Claims (1)

[Claims] Among the pulse trains of each phase generated by the rotation of a rotary encoder having multiphase output, the generation timing between specific pulses of each phase generated corresponding to a predetermined rotational position of the rotary shaft of the rotary encoder is determined for each rotation. Evaluation of rotary shaft runout of a rotary encoder, characterized in that the magnitude of the aperiodic component of the rotary shaft runout of the rotary encoder is evaluated by detecting the amount of variation of the time difference of the occurrence timing for each rotation. Method.