JPH05149711A - Three-phase linear scale - Google Patents

Abstract

PURPOSE:To obtain an inexpensive three-phase linear scale having high detection accuracy by eliminating low stop accuracy due to the lack of positional information about the vicinity of a stopping position seen in the conventional linear scale. CONSTITUTION:This three-phase linear scale is composed of a linear scale main body 11 provided along the traveling route of a traveling object 12, detecting head 13 mounted on the main body 11 closely to the object 12, and detecting and arithmetic section 14. The main body 11 has a group of light inputting ports having a 1/2-pitch width and arranged at regular pitches along the traveling route of the object 12 and the head 13 is provided with three sets of light-transmissive analog sensors 15 which are arranged in the running direction of the head 13 so that the sensors 15 can be shifted from the pitches of the light inputting ports by 1/3 pitches. The section 14 obtains a group of three-phase alternative signals having phase shifts corresponding to the detection accuracy by calculating the three-phase analog outputs of the sensors 15 and outputs a positional signal by detecting the positive-negative value changing points of the signals.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-phase linear scale which outputs position information of a moving body.

[0002]

2. Description of the Related Art As shown in FIG. 12, a conventional linear scale that outputs position information to a traveling control unit by a linear scale main body provided along a moving path and a detection element mounted on the moving body A detection head 2 including a detection element indirectly connected to the linear scale main body 1 fixed along the movable scale 3 so that the vibration of the mobile body 3 is not directly transmitted is moved as the mobile body 3 travels, and position information is transferred to a sequencer, a microcomputer, or the like. The control unit 4 controls the position of the moving body by accelerating and decelerating and stopping the traveling motor M through a control system that performs necessary processing such as a calculation counter and is built in the control unit 4. ing.

In the linear scale that outputs position information as described above, the main body of the linear scale and the detection head are provided in a non-contact state, and the detection element is a proximity switch or a reed switch that operates by magnetic lines of force. The object to be detected provided at the position is detected, a position signal which is an absolute address corresponding to the stop position is output, and the traveling motor is controlled by comparing with a target address preset in the control unit 4. I have to.

[0004]

In the conventional linear scale, since the mutual influence of adjacent detecting elements is large, the setting interval is also large, so that the position information providing density is sparse and the position information near the stop position is poor. It was difficult to obtain high stopping accuracy. Further, there is a limit in using a photoelectric tube that does not affect the detection element or using an encoder. An object of the present invention is to solve the above problems and provide a three-phase linear scale that is inexpensive and has high detection accuracy.

[0005]

In order to achieve the above object, a three-phase linear scale of the present invention is a linear scale main body having a moving body along a moving path, and a moving body positioned close to the linear scale main body. The linear scale main body has a light input port group having a uniform pitch and a 1/2 pitch width along the movement path, and the detection head includes the detection head mounted above. It has three sets of light-transmissive analog sensors arranged in the running direction so as to have a pitch shift of 1/3 pitch with respect to the pitch of the input port, and the detection calculation section outputs from the three sets of analog sensors. A three-phase alternating signal group having a phase shift corresponding to the detection accuracy is obtained by calculating the three-phase analog output, and the positive and negative conversion points of those signal values are detected to output the position signal. Characterize. Further, the linear scale main body may alternately have equal-length light-reflecting surfaces and non-reflecting surfaces along a moving path of the moving body, and the analog sensor may be of a reflective type.

[0006]

Since the three-phase linear scale of the present invention has the above-described structure, the three-phase analog sensor built in the head by the traveling of the moving body is the light input port of the linear scale main body arranged along the moving path. The group outputs a three-phase analog signal having a phase shift of ⅓ of the pitch of the input port (120 ° when one pitch of the input port is 360 °). Next, the difference is calculated by the calculation unit and converted into a three-phase alternating signal. This conversion signal can output a position signal for each 1/6 pitch (P / 6), but for higher required detection accuracy, P / 12, P / 24,
Obtaining a three-phase alternating signal with a phase shift of P / 48,
Positive and negative turning points of those signal values are detected, and position signals corresponding to the detection accuracies P / 12, P / 24, P / 48 ... Are output.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the drawings. FIG. 1 is a front view showing an embodiment of a three-phase linear scale of the present invention, and FIGS. 2 and 3 are a vertical plan view and a side view of FIG. In the figure, 10 is a moving path, 11 is a linear scale main body provided along the moving path, 12 is a moving body, 1
3 is a detection head mounted on the moving body 12, 14 is a detection calculation unit, 15 is three sets of analog sensors attached to the detection head 13, 16 is a light input port, and P is a pitch of the light input port 16. As shown in the figure, the linear scale main body 11 is a horizontal strip-shaped member provided along the movement path 10 and includes the light input port 1
6 have a width of P / 2 and are arranged at equal pitches. The detection head 13 is mounted on the moving body 12 and runs along a moving path by a built-in motor M. The analog sensor 15 attached to the head 13 has a position shift of 1/3 of the pitch P of the light input port 16 and, as shown in FIG. 1, P / 2 ± P / 3 = 5P / 6 or P / 6. Are provided with a space between them, and each of the light projecting portion 15a and the light receiving portion 15b
It has a transparent structure.

4, 5 and 6 are plan views and front views of another embodiment in which light reflecting surfaces and non-reflecting surfaces are alternately provided along the moving path of the moving body 12 and the analog sensor is a reflection type. Figure,
Side views are shown respectively. That is, the linear scale main body 21 has the same length of the light reflecting surface 2 along the moving path of the moving body 12.
6 and the non-reflective surface 27 are alternately provided at an equal pitch P,
Moreover, both the reflective surface 26 and the non-reflective surface 27 have a width of P / 2. Corresponding to this, the detection head 23 is mounted on the moving body 22 and has a reflection type analog sensor 25 having a light receiving portion 25b at the central axis portion in the traveling direction and light emitting portions 25a on both sides thereof on the reflection surface. It is arranged so as to have a pitch of P / 3 for each pitch P.

Next, the operation of the above device will be described. When the moving body 12 or 22 travels along the linear scale main body 11, the linear scale main body 11 and the detection head 1
Depending on the positional relationship with 3 or 23, the output (A) of three phases from the analog sensor 15 or 25 as shown in FIG.
(B) and (C) are obtained. This analog output may be sinusoidal or triangular. This is calculated by the detection calculation unit 14, and the three-phase alternating signal A = (A) − (B) shown in FIG.
Convert to B = (B)-(C) and C = (C)-(A).
The converted signal A changes from positive to negative at point P / 6, and at point 4P / 6
Changes the value from negative to positive. Similarly, the value of signal B changes from negative to positive at point 0, the value of positive changes from negative to positive at point P / 2, and the value of signal C changes from negative to positive at point 2P / 6 and from positive to negative at point 5P / 6. Change. In this way, if the detection calculation unit 14 detects the points where the values of the signals A, B, and C change from positive to negative and from negative to positive, respectively.
By outputting a position signal having a phase shift of / 6, the detection accuracy becomes P / 6. That is, if P = 24 m / m, the detection accuracy is 4 mm.

Next, as shown in FIG. 9, the signals A,
For B and C, D = 1/2 (AB), E = 1/2 (B-
C), F = 1/2 (CA), G = 1/2 (BA),
If six signals of H = 1/2 (C-B) and I = 1/2 (A-C) are added and the points where each signal changes from positive to negative and from negative to positive are detected, A pulse train with a phase shift of P / 2 is output and the detection accuracy is 2 mm. Further, as shown in FIG. 10, in nine signals A, B, C, D, E, F, G, H, and I in FIG. 9, J = 1/2 (C−I) = 1/2 ( C + F),
K = 1/2 (A-G) = 1/2 (A + D), L = 1/2
(B-H) = 1/2 (B + E), M = 1/2 (C-
E), N = 1/2 (A-F) and R = 1/2 (B-D) are added to detect points where each changes from positive to negative and from negative to positive, P / 24 A pulse train with a phase shift of is output and the detection accuracy is 1 mm.

The three-phase alternating signal for position information is determined as follows. For example, a case of R = 1/2 (BD) will be described. Point P / 24 and point 2P in FIG.
The case of obtaining an alternating signal passing between / 24 is as follows. Since the X coordinate of the point P / 24 corresponds to the X coordinate of the intersection (R) of the signal B and the signal D, the relational expression of the signal to be obtained is R = 1/2 (BD). In this way, the alternating signal K-N-J- that passes the points of 3P / 24 or less.
The relational expression of M and L is K = 1/211 (AG) = 1/2
(A + D), N = 1/2 (A-F), J = 1/2 (C-
I), M = 1/2 (CE), and L = 1/2 (BH). Further, as shown in FIG. 11, the relational expressions of the alternating signals passing through the points, ..., Are 1/2 (RB), 1/2 (GR), −, respectively.
1/2 (K-G) ... and a position having a phase shift of detection accuracy P / 48 (P / 48 = 0.5 mm when P = 24 mm) when positive / negative conversion points of the alternating signal are detected. A pulse train that is a signal can be output.

[0012]

As described above, according to the three-phase linear scale of the present invention, the three-phase linear scales for position information having a phase shift corresponding to the detection accuracy from the three-phase analog outputs output from the three sets of analog sensors. Since the phase alternating signal is obtained, it is possible to provide a linear scale with low cost and high accuracy that can detect fine positions with three sensors.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of a three-phase linear scale of the present invention.

2 is a vertical plan view of FIG.

FIG. 3 is a side view of FIG.

FIG. 4 is a plan view showing another embodiment of the three-phase linear scale of the present invention.

FIG. 5 is a front view of FIG.

FIG. 6 is a side view of FIG.

FIG. 7 is a chart showing a three-phase analog output having a shift of 2/3 of the three-phase analog sensor of the present invention.

8 is a chart showing a three-phase alternating signal group having a P / 3 shift obtained by the calculation of a detection calculation unit from the three-phase analog output of FIG. 7, and showing that a pulse train having a P / 6 phase shift is output. Is shown.

9 is a diagram showing the three-phase alternating signal of FIG. 8 with D, E, F, G, H, I
5 is a chart showing a three-phase alternating signal group that outputs a pulse train having a P / 12 phase shift by adding the alternating signal of FIG.

FIG. 10 shows N, J, R, K, in addition to the three-phase alternating signal group of FIG.
It is a chart which shows the three-phase alternating signal group which outputs the pulse train of the phase shift of P / 24 by adding the alternating signal group of M and L.

11 is a chart showing a method of obtaining a three-phase alternating signal group which outputs a pulse train having a phase shift of P / 48 from the three-phase alternating signal group of FIG.

FIG. 12 is a diagram showing an outline of a conventional linear scale.

[Explanation of symbols]

 10, 20 Moving path 11,21 Linear scale body 12,22 Moving body 13,23 Detection head 14 Detection calculation section 15 Transmission type analog sensor 25 Reflection type analog sensor 26 Reflection surface 27 Non-reflection surface

Claims (2)

[Claims] 1. A linear scale main body provided along a moving path of a moving body, a detection head mounted on the moving body at a position close to the linear scale main body, and a detection calculation unit, the linear scale main body comprising: There is a group of light input ports having an equal pitch and a ½ pitch width along the movement path, and the detection head has a deviation of 1/3 pitch from the pitch of the light input ports in the traveling direction. 3 sets of light-transmissive analog sensors, the detection / calculation section calculates 3-phase analog outputs output from the 3 sets of analog sensors and has a phase shift corresponding to the detection accuracy. A three-phase linear scale having a configuration in which an alternating signal group is obtained, positive and negative conversion points of those signal values are detected, and a position signal is output. 2. The linear scale main body alternately has equal-length light reflecting surfaces and non-reflecting surfaces along a moving path of a moving body, and the analog sensor is a reflective analog sensor. The three-phase linear scale according to claim 1, which is characterized in that.