JP2861712B2 - Linear encoder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear encoder capable of outputting a pulse signal over a long distance by moving a slit gauge.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 11, a slit gauge 1 is fixed to a fixing portion 5 side.
A pulse detector (hereinafter simply referred to as a pickup) 2 is provided on the movable section 6 side, and the movement of the movable section 6 is detected by the movement of the pickup 2.

[0003]

However, when positioning a crane in a factory such as an automatic crane, for example, the moving distance of the crane as the movable portion 6 becomes long. 1 must be provided for the length of the movement distance. Since the slit gauge 1 is manufactured by precisely forming slits, there is a problem that the cost is increased. Also, it is difficult to manufacture a long slit gauge for maintaining accuracy, and it is liable to be damaged. In the case of the rotary type, the cost is relatively low. However, when there is a problem such as slippage between the motor and the machine, the position may not be detected directly because the position is not directly detected.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and provides a linear encoder which is long-distance, low-cost, and easy to handle by providing a slit gauge on a movable portion side. As a first object. A second object of the present invention is to provide a linear encoder with high accuracy for processing signals from a plurality of pulse detectors into a continuous signal sequence. Further, a third object of the present invention is to provide a linear encoder capable of simplifying wiring for leading a pulse from a plurality of pulse detectors to a detector selection means.

[0005]

According to a first object of the present invention, as shown in FIG. 1, one slit gauge 1 is provided on the movable part 6 side, and the slit gauge 1 is provided on the fixed part 5 side. Are provided with a plurality of pulse detectors 2a to 2e at intervals equal to or less than the length of the gauge 1 and a detector selection means 3 for continuously combining and outputting output signals from the respective pulse detectors. A linear encoder is provided. According to this configuration, the length of the slit gauge 1 may be longer than the interval between the plurality of pulse detectors 2a to 2e... And can be set arbitrarily, so that the length of the slit gauge 1 is shortened. be able to.

According to a second object of the present invention, as shown in FIG. 2 and FIG.
A and B phases have slit portions 1a and 1b so that the phase and Z phase output signals can be detected.
Each of the phases has a plate-shaped slitless portion 1z, and the detector selecting means 3 switches the odd-numbered 2a, 2c, and 2e Z-phase signals from high to low when the odd-numbered Z-phase signals are switched from high to low. The A-phase 1a and B-phase 1b output signals output from the high-level detectors of the even-numbered 2b and 2d pulse detectors are selectively output, and the Z-phase is output from the odd-numbered 2a, 2c and 2e pulse detectors. Conversely, when the signal of 1z switches from low to high, the switched odd-numbered 2a, 2c, 2e
A linear encoder is provided, which selectively outputs the output signals of the A phase 1a and the B phase 1b output from the detector. According to the above configuration, the A-phase and B-phase pulse signals from the plurality of pulse detectors 2a to 2e... Can be selected by the Z-phase signal and processed into a continuous pulse signal train.

According to a third object of the present invention, as shown in FIG. 10, the pulse detectors 2a, 2b.
Phase, B phase and Z phase are connected to respective A phase bus 22a, B phase bus 22b and Z phase bus 22c, and Z phase passes through the Z phase bus 22c and the detector selecting means 3
And a control address signal from the detector selecting means 3 is introduced to each of the pulse detectors 2a, 2b, 2c... Via an address signal bus 22d. According to the above configuration, the plurality of pulse detectors 2a, 2b, 2c,.
From the A-phase bus 22
The operation can be simply performed using the a-phase B bus 22b, the Z-phase bus 22c, and the address signal bus 22d.

[0008]

Embodiment 1 As shown in FIG.
Are provided on the movable portion 6 side, and a plurality of pickups 2a to 2e (2a to 2e) as pulse detectors are provided on the fixed portion 5 side such as a crane rail at regular intervals equal to or less than the slit gauge length.
e) Provide. The structure of the slit gauge 1 is as shown in FIG. 2; an A-phase slit portion 1a, a B-phase slit portion 1b shifted by a half pulse width from the A-phase, and a Z-phase slitless portion 1Z having no slit. And As shown in FIG. 3, the light emitting elements 7a,
Pickups 2a to 2e consisting of light-receiving elements 8a, 8b, 8z are provided, and in the portion where the window-shaped slit gauges 1a and 1b are formed, the light-emitting elements 7a, 1b are provided.
The light of a and 7b reaches the light receiving elements 8a and 8b, and the light of the light emitting elements 7a and 7b is blocked by the slit gauge 1 and does not reach the light receiving elements 8a and 8b in the portion where the slits 1a and 1b are not formed. Therefore, a rectangular wave pulse output is obtained from the light receiving element. Incidentally, the light receiving elements 8a and 8
The output signal b is shaped into a rectangular pulse by the waveform shaping circuits 9a and 9b. Since no slit is formed in the Z-phase slitless portion 1Z of the slit gauge 1, light of the light emitting element 7z is blocked over the entire length of the slit gauge 1, and the pickup 1 passes through the Z-phase slitless portion 1Z. Then, since an output is obtained from the light receiving element 8z, as an output signal of the waveform shaping circuit 9c, a pulse signal rises when the pickup is applied to the slit gauge 1 and falls when the slit gauge 1 comes off. A rectangular pulse having a long pulse width is obtained.

As shown in FIG. 1, for example, a case may occur in which two pickups 2b and 2c simultaneously and redundantly detect signals from the slit gauge 1. In the case of the duplication detection, the pickup selector 3 sets each pickup 2b
Pickup 2 by the Z-phase signal from
It determines which of b and 2c is to be selected, and outputs the A-phase and B-phase signals of the selected pickup.

FIG. 4 shows a pickup selection method. FIG.
, The black pickup is the selected pickup. As shown in FIG. 4A, when only the odd-numbered pickup 2a detects the signal of the slit gauge 1, the pickup 2a is selected. FIG.
As shown in (2), the odd-numbered pickup 2a
Not only that, even if the even-numbered pickup 2b starts detecting the signal of the slit gauge 1, the odd-numbered pickup 2a remains selected. As shown in FIG. 4C, when only the even-numbered pickup 2b detects the signal of the slit gauge 1, the pickup 2b
Is selected. As shown in FIG. 4D, when not only the even-numbered pickup 2b but also the odd-numbered pickup 2c starts detecting the signal of the slit gauge 1, the odd-numbered pickup 2c is selected.

FIG. 5 shows the slit gauge 1 shown in FIGS.
The Z-phase signal state of each of the pickups 2a to 2e when in the position (7) and a pickup selection method are shown. In FIG. 5, a signal H indicates that the Z-phase signal state of the pickup is high, and a signal L indicates that the Z-phase signal state of the pickup is low. 4 (2) to 4
When shifting to (3), the odd-numbered pickup 2a
Select the pickup 2b in the H state at the fall of the Z phase. When shifting from FIG. 4 (3) to FIG. 4 (4),
The pickup 2c in the H state is selected at the rise of the Z-phase of the odd-numbered pickup 2c. 4 (5) to 4
When shifting to (6), the odd-numbered pickup 2c
Select the pickup 2b in the H state at the fall of the Z phase. When shifting from FIG. 4 (6) to FIG. 4 (7),
The pickup 2a in the H state is selected when the Z-phase of the odd-numbered pickup 2a rises. As shown in FIG. 5, the pickups are switched at the rising and falling edges of the Z-phase of the odd-numbered pickups 2a, 2c.

FIG. 6 shows a flowchart of the pickup selecting process. When the selection process is started, step 101
Then, it is determined whether the Z-phase signal of the odd-numbered pickup has fallen (H → L), and if it is (Y), at step 103, the Z-phase of the other pickups becomes H
Select a state pickup. If step 101 is negative, it is determined in step 102 whether the Z-phase signal of the odd-numbered pickup has risen (L → H). If yes (Y), it has risen in step 104 ( L → H) Select the odd-numbered pickup. If no (N) in step 102, step 1
At 05, the pickup selection process ends.

FIGS. 7 and 4 show the outline of the pulse synthesis accuracy. As shown in FIG. 4C, when the slit gauge 1 is moving rightward and the pickup 2b is selected, the B-phase signal of the pickup 2b is the output signal of the pickup selector 3. FIG. 4 (4)
When the slit gauge 1 is moving rightward and the Z-phase signal of the odd-numbered pickup 2c rises, the pickup 2c is selected, and the B-phase signal of the pickup 2c is supplied to the pickup selector 3 as shown in FIG. Output signal. As shown in FIG. 4 (5), when the slit gauge 1 is moving to the left and the odd-numbered pickup 2c is selected, the B-phase signal of the pickup 2c is output from the pickup selector 3. Signal. As shown in FIG. 4 (6), the slit gauge 1 is moving to the left and the odd-numbered pickup 2c
, The B-phase signal of the pickup 2 b becomes the output signal of the pickup selector 3. here,
When the slit gauge 1 moves rightward and leftward, the rising and falling positions of the Z-phase signal of the pickup 2c are the same as shown in FIG. A shift ΔL of a maximum of one pulse between the signal and the B-phase signal of the pickup 2c becomes a pulse synthesis error, and the amount thereof can be kept constant. However, in the slit gauge 1 for generating a large number of pulses, a deviation of one pulse at the maximum does not pose a problem for obtaining the required accuracy unless it is normally accumulated. In this case, there is no problem because the rising and falling positions are the same. If a problem arises, the error is constant at the rising and falling positions, so that the calculation can be corrected at the pickup switching timing. With the above configuration, a pulse signal is continuously obtained on the output side of the pickup selector 3 using a plurality of pickups, and the movement amount of the slit gauge 1 can be detected.

Unless the pickups are fixed to the fixed part 5 so that the waveforms of the pickups 2a to 2e do not shift, an error ΔL corresponding to the shift occurs at the rising and falling portions of the Z-phase signal. If not, no problem. Therefore, in the first embodiment, as shown in the flowchart of FIG. 6, switching for pickup selection is performed every other pickup 2a to 2e..., And the falling of the Z-phase signal of the odd-numbered pickup or the even-numbered pickup is performed. By determining the pickup to be selected based on the (H → L) and rising (L → H) signal changes, the pickup can be switched at the same absolute position both when traveling to the right and when traveling to the left. Has been eliminated. By forming the slit so as to synchronize the Z-phase with the rising edge of any of the A-phase and the B-phase, the error of the pickup 2c is eliminated.
Is not more than one pulse. It should be noted that the pickups 2a to 2e do not simultaneously output signals from the three pickups 2a to 2e.
Is a condition.

As shown in FIG. 8 (3), when the slit gauge 1 moves rightward, the Z-phase signal of the pickup 2b rises (for H), for example, as in the case of FIG. 4 (3). At this time, the B-phase signal is output as it is. FIG.
When the front edge of the slit gauge 1 contacts the pickup 2c as shown in (4), both pickup 2b and 2c signals are output. These pickups 2b and 2c
When the signals are combined by the pick-up selector 3, the initial A-phase and B-phase output signals include a ΔL shift. After that, when the slit gauge 1 advances leftward, FIG.
As shown in (6), the B-phase output signal and the A-phase output signal after being combined by the pickup selector 3 include a deviation of ΔL. However, as described above, in the present invention, the switching is performed by every other pickup, so that the Z-phase signal rises and rises at the absolute same position both when the slit gauge 1 advances rightward and when it advances leftward. Since the switching position is the same due to the occurrence of the drop, the accumulation of errors due to repetition of reciprocation between different pickups 2b and 2c is eliminated.

[0016]

Second Embodiment In the second embodiment, as shown in FIG. 9, a direction discriminating circuit 10, a positive / negative counter circuit 11, and a display output circuit 12 are provided inside a pulse counter means 4. Further, a reference limit switch 13 is provided to adjust the movable section 6 to a reference point. At first, the slit gauge 1 is first adjusted to the reference point by the reference limit switch 13, and a reset signal is input to the counter circuit 11 of the pulse counter means 4. After the counter circuit 11 is cleared to zero or set to a predetermined count number, the count number becomes normal.
The positive / negative pulse for counting is selected by the pickup selector 3
A pulse obtained as a positive / negative pulse by the direction discriminating circuit 10 from the A-phase and B-phase pulse waveforms selected by the above is used. The A-phase and B-phase pulses entering the direction discriminating circuit 10 are the A-phase signal and the B-phase signal from the pickup selected by the pickup selector 3 based on the Z-phase signal. The pulse output generated by the pickup 2a is a positive pulse in which the A-phase signal is advanced by 1/4 period from the B-phase signal when the movable unit 6 advances rightward as shown by the arrow, and the movable unit 6 moves leftward. When the signal advances, the A-phase signal is a negative pulse delayed by １ ／ cycle from the B-phase signal. When the slit gauge 1 has not reached the pulse detector 2b, the pulse detector 2b
, The A-phase signal, the B-phase signal and the Z-phase signal are all L signals only.

In the first and second embodiments, A
Since the phase slit section 1a and the B-phase slit section 1b are provided on the slit gauge 1 in a form shifted by 1/4 period as shown in FIG. Since the way of outputting the waveforms of the A-phase slit portion 1a and the B-phase slit portion 1b is different between the delay and the advance depending on the difference between the moving direction in the left direction and the moving direction in the left direction, it can be used mainly for discriminating the moving direction. . In addition, the resolution can be increased up to four times using the rise and fall of the Z phase. 2 (A phase and B phase) × 2 (Z phase rising and falling) = 4 (times) However, when it is not necessary to increase the resolution, only one phase of the A phase or the B phase is provided in the slit gauge 1. Alternatively, only one of the rise and fall of the Z phase may be used.

FIG. 10 shows a third embodiment. The third embodiment reduces the number of wirings by adopting a bus format.
Each of the pickups 2a, 2b, 2c,.
Light-emitting elements and light-receiving elements for generating phase and Z-phase outputs are built in, and the wiring from each light-emitting element and light-receiving element becomes enormous unless the number of pickups used is large. In the third embodiment, for example, the pickup 2a
, B-phase, and Z-phase pulse detection circuit 14
And a switch control processing circuit 15, an address conversion circuit 16, an address comparison circuit 17, and an address setting circuit 1.
8 and an electronic switch 19 are provided. Further, an address reading circuit 20 and an address conversion circuit 21 are provided inside the pickup selector 3. A direction discriminating circuit 10, a positive / negative counter circuit 11, and a display output circuit 12 are provided inside the pulse counter means 4. The bus 22 is an A-phase bus 22a, a B-phase bus 22b, and a Z-phase bus 2
2c and an address signal bus 22d.
In the above configuration, when each Z-phase pulse is switched to H or L, the address setting circuit 18 outputs an address-added Z-phase signal to which an address signal set in advance is added from the address conversion circuit 16 through the address signal bus 22d. Then, it is sent to the address reading circuit 20 of the pickup selector 3. From the address read by the address reading circuit 20, the Z phase of which pickup is H or L
Is stored in the pickup selector 3.
The pickup selector 3 determines which Z-phase pulse of the odd-numbered pickup has been switched to H or L and which pickup is currently selected as a reference. When the pulse signal is switched from H to L, the Z-phase pickup is selected from the adjacent pickups,
When the Z-phase pulse signal of the odd-numbered pickup switches from L to H, the next pickup is selected by a method of selecting the switched pickup.
The control address signal of the pickup selected through the address conversion circuit 21 is sent to the address comparison circuit 17 of each pickup. The address comparison circuit 17 compares the address signal with its own address signal set in advance, and instructs the switch control processing circuit 15 to turn on the internal electronic switch 19 only when the address signals are equal to each other, and outputs A-phase and B-phase pulse signals. Therefore, signals from other unselected pickups can be cut, and only the signal of the selected specific pickup can be made valid. The direction discriminating circuit 10 of the pulse counter means 4 converts the A-phase signal and the B-phase signal from the selected specific pickup into positive and negative pulses, and the counter circuit 11 counts positive and negative.
The result is output to an output circuit 12 such as a display.

[0019]

As described above, in the linear encoder of the present invention, one slit gauge is provided on the movable part side, and a plurality of pulse detectors are provided on the fixed part side at intervals equal to or less than the slit gauge length. Since there is provided a detector selecting means for continuously combining and outputting output signals from the pulse detector, it is possible to provide a low-cost and easy-to-handle linear encoder as a long-distance and high-precision positioning sensor. There is an excellent effect that it can be done. Further, in the second invention, the slit gauge has a slit portion in the A phase and the B phase so that an output signal of the A phase, the B phase and the Z phase can be detected, and a plate shape is provided in the Z phase. When the Z-phase signal from the odd-numbered pulse detector switches from high to low, the detector selection means selects an even-numbered or odd-numbered pulse other than the switched detector. When the A-phase and B-phase output signals output from the high-level detector are selectively output and the Z-phase signal from the odd-numbered pulse detector is switched from low to high, Since the A-phase and B-phase output signals output from the switched odd-numbered pulse detectors are selectively output, no error accumulation occurs even when the slit gauge reciprocates the same pulse detector many times. Linear encoder An excellent effect that it is possible to provide. Further, in the third invention, the pulse detector includes each A
Phase, B phase and Z phase are connected to the respective A phase bus, B phase bus and Z phase bus, and the Z phase is coupled to the detector selection means via the Z phase bus, and the detector selection means Since the control address signal is supplied to each pulse detector via the address signal bus, there is an excellent effect that wiring for leading a pulse from a plurality of pulse detectors to the detector selection means can be simply performed. .

[Brief description of the drawings]

FIG. 1 is a front view showing a first embodiment.

FIG. 2 is a front view showing a configuration of a slit gauge.

FIG. 3 is a side view showing a related configuration of a slit gauge, a light emitting element, and a light receiving element.

FIG. 4 is a timing chart schematically showing a pickup selection method.

FIG. 5 is a diagram illustrating a Z-phase signal state of each pickup and a pickup selection method.

FIG. 6 is a flowchart illustrating a pickup selection process.

FIG. 7 is a waveform diagram of an output signal from a pickup selector showing a pulse synthesis accuracy.

FIG. 8 is a timing chart showing details of a pickup selection method.

FIG. 9 is a configuration diagram for explaining a second embodiment.

FIG. 10 is a configuration diagram for explaining a third embodiment.

FIG. 11 is a front view showing a conventional technique.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Slit gauge, 2a, 2b, 2c ... Pickup, 3 ... Pickup selector, 4 ... Pulse counter means, 6 ... Movable part, 7a-7c ... Light emitting element,
8a to 8c: light receiving element, 22: bus, 22
a ... A phase bus, 22b ... B phase bus, 22c ... Z phase bus, 22d ... address signal bus.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01B 11/00 G05D 5/36 G01B 21/00

Claims (3)

(57) [Claims] 1. A linear encoder for converting a moving distance of a movable part into a pulse number by a slit gauge, a light emitting element and a light receiving element, wherein one slit gauge is provided on the movable part side and the slit is provided on the fixed part side. A linear encoder comprising: a plurality of pulse detectors provided at intervals equal to or less than the gauge length; and a detector selecting means for continuously combining and outputting output signals from the respective pulse detectors. 2. The slit gauge has a slit portion in the A phase and the B phase so that an output signal of the A phase, the B phase and the Z phase can be detected, and a plate-shaped non-slit portion in the Z phase. And when the Z-phase signal from the odd-numbered pulse detector switches from high to low, the detector selection means includes an even-numbered or odd-numbered pulse detector other than the switched detector. The A-phase and B-phase output signals output from the high-level detector are selectively output, and when the Z-phase signal from the odd-numbered pulse detector switches from low to high, the switching is performed. A linear encoder for selectively outputting A-phase and B-phase output signals output from the odd-numbered or even-numbered pulse detectors. 3. The pulse detector according to claim 1, wherein each of the A-phase, B-phase and Z-phase is connected to a respective A-phase bus, B-phase bus and Z-phase bus, and the Z-phase is detected via the Z-phase bus. And a control address signal from the detector selection means is introduced to each pulse detector via an address signal bus.