JPH06147918A - Multi-rotary absolute type rotary encoder - Google Patents

Abstract

PURPOSE:To provide a compact multi-rotary type rotary encoder which necessitate no optical-axis adjustment, etc., and accurately aligns the changing point of minimum resolution with the changing point of the number of revolutions. CONSTITUTION:While light emitting diodes for light projection being set as 6b to 6d, an light emitting diode 6a corresponding to an MSB and an MSB-1 is pulse-lighten by a pulse generating circuit 17 when the power is turned off. Then the rotary direction and the number of revolutions are detected based on its 2-bit output and the number of revolutions is stored by a counter. Thus, a multi-rotary type rotary encoder is constructed by holding the number of revolutions while the power is turned off.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-rotation absolute type rotary encoder capable of detecting an absolute position over one rotation and multiple rotations.

[0002]

2. Description of the Related Art The conventional multi-rotation type absolute type rotary encoder is shown below. Figure 1
1 is a schematic view showing an example of a conventional rotary encoder. As shown, a rotary plate 1 is attached to a rotation detecting shaft 101.
02 is attached. A gray code pattern is formed on the rotary plate 102, as will be described later.
The parallel light from 3 irradiates the rotary plate 102. Then, the rotational position of the rotary plate 102 is detected by the parallel output obtained from the plurality of light receiving elements 104. And this axis 1
The gear 105 is attached coaxially with 01, and the gear 10
A reduction mechanism is formed by 6, 107 and 108, and the reduced gear 108 is connected to the rotary plate 109.
Similarly to the rotary plate 102, the rotary plate 109 is also formed with a gray code pattern. This reduction mechanism is a rotating plate 102.
The rotation plate 109 is configured to change its angle by one bit per one rotation. The light projecting unit 1 is provided on the side of the rotary plate 109.
A light receiving element 111 for receiving 10 and its signal through the slit is provided. In this way, the rotation angle of the shaft 101 is read from the light receiving element 104, and the rotation number thereof is read from the light receiving element 111, so that the rotation number and the rotation angle can be detected.

In another type of rotary encoder shown in FIG. 12, a rotary plate 102 is provided on a shaft 101, the rotation angle of which is read by a light projecting section 103 and a light receiving element 104, and a magnetic type is coaxially arranged on the rotary shaft 101. A magnetic rotating plate 112 for detecting the number of rotations is attached. Then, the change in the magnetic pole of the magnetic rotating plate 112 is read by the magnetic detection element 113, and the value is counted by the counter 114 to identify the number of rotations. In this case, the backup power supply 115 is required to back up the counter 114 even when the power supply is stopped.

[0004]

However, as shown in FIG. 11, in a multi-rotation rotary encoder using a speed reduction mechanism, a plurality of absolute type detection parts are required, which is not only expensive but also large in size. . Further, there is a drawback that the life of the gear is shortened due to wear of the gear. Furthermore, because it is necessary to change the number of revolutions accurately at the origin position,
There was also a drawback that the gear had to be manufactured with high precision.

On the other hand, the multi-rotation rotary encoder using the magnetic rotating plate has a drawback that it is necessary to accurately align the position of the magnetoresistive element. Further, even when the rotation speed is backed up by the backup power supply when the power is off, the shaft 101 may be manually rotated from the outside.
Therefore, the magnetic detection element 113, the counter 114, and the like need to be operated even when the power is turned off, which has a drawback that the configuration becomes complicated.

The present invention has been made by paying attention to the problems of such a conventional multi-rotation absolute type rotary encoder, and does not use a plurality of rotary plates or magnetic rotary plates, or when the power is off. A technical problem is to be able to accurately detect the rotational speed even when a rotational force is applied from the outside.

[0007]

According to a first aspect of the present invention, there is provided a rotary plate which is connected to a rotary shaft and has slits of different patterns formed along a plurality of concentric circles corresponding to a rotation angle, and a rotary plate. A light projecting element for projecting light to the plate, a plurality of light receiving elements for receiving the light of the light projecting element through the slits of the rotating plate, and a plurality of discriminating parallel outputs obtained from the plurality of light receiving elements with a predetermined threshold value. Rotation angle detection means for detecting the rotation angle of the rotation axis according to the parallel output of the comparison circuit, a clock generation circuit for generating a predetermined clock when the power is turned on, MSB of the light receiving elements, Rotation detecting means for detecting one rotation of the rotating plate based on the light receiving signal of MSB-1, and rotation direction detecting means for detecting the rotating direction of the rotating plate based on the light receiving signals of MSB and MSB-1 among the light receiving elements. , Rotation direction detection hand Counter for counting the output of the rotation detecting means in either the up direction or the down direction according to the output of the pulse generator, the pulse generation circuit for generating a pulse for lighting the light projecting element, and the light projecting element when the power is turned on. The light emitting element driving means that continuously lights up and the light emitting element is pulse-lighted based on the output of the pulse generating circuit when the power is off, the pulse generating circuit, the rotation detecting means, the rotation direction detecting means, the light emitting element driving means and the counter. A rotation angle detecting means comprising a battery for supplying power and a clock selecting means for selecting the output of the pulse generating circuit and the clock generating circuit according to the on / off of the power source and giving the rotation detecting means and the rotation direction detecting means. Is used to detect the rotation angle and the counter to detect the rotation speed.

According to a seventh aspect of the present invention, the rotary plate is connected to the rotary shaft, and the slits having different patterns are formed along a plurality of concentric circles in accordance with the rotation angle, and the light is projected onto the rotary plate. A light projecting element, a plurality of light receiving elements that receive the light of the light projecting element through the slit of the rotary plate, and a plurality of comparison circuits that discriminate parallel outputs obtained from the plurality of light receiving elements with a predetermined threshold value, Rotation angle detection means for detecting the rotation angle of the rotation axis according to the parallel output of the comparison circuit, a clock generation circuit for generating a predetermined clock when the power is turned on, and light reception signals of MSB and MSB-1 among the light reception elements. A rotation detecting means for detecting one rotation of the rotating plate based on the above, a rotating direction detecting means for detecting the rotating direction of the rotating plate based on the light receiving signals of MSB and MSB-1 among the light receiving elements, and the rotating direction detecting means. Depending on the output A counter that counts the output of the rotation detection means in the up direction and the down direction, a rotation speed detection means that detects the rotation speed based on the comparison output of the light reception signals of one of the light receiving elements, and the rotation speed detection means. LED that generates a pulse of a frequency corresponding to the rotating speed
CK generating means, a light projecting element driving means for continuously lighting the light projecting element when the power is turned on, and a pulse lighting of the light projecting element based on the output of the LEDCK generating means when the power is turned off, a rotation speed detecting means, and an LEDCK generating means. , A rotation detecting means, a rotation direction detecting means, a light projecting element driving means, a battery for supplying power to the counter, and an output of the LEDCK generating means and a clock generating circuit according to the on / off of the power source. Clock selection means to be provided to the direction detection means,
The rotation angle detecting means detects the rotation angle and the counter detects the rotation number.

[0009]

According to the invention of claim 1 of the present application having such a feature, the clock signal of the clock generating circuit is given to the rotation angle detecting means, the rotation speed detecting means and the rotation direction detecting means when the power is turned on. In this state, the light projecting element is continuously lit, and a rotation angle signal is obtained according to the rotation of the rotary plate. Further, the up / down counter is up-counted or down-counted according to the rotation direction and the rotation speed of the rotary plate, and the rotation speed and the rotation angle can be detected by the rotation angle / rotation angle detection means by the output of this counter. On the other hand, when the power is turned off, the clock generating circuit is stopped, and instead of this, the pulse generating circuit is operated by the battery and the light emitting element is pulse-lit. Although the rotation angle detection means is inoperative, the rotation speed detection means, the rotation direction detection means, and the counter are energized by a battery so as to be operated to detect the rotation speed of the encoder.

Further, in the invention of claim 7 of the present application, when the power is off, the rotational speed is detected based on the change in the output of the light receiving signal of any one of the light receiving elements. Then, in correspondence with the rotation speed, a pulse having a higher frequency when the rotation speed becomes higher and a pulse having a lower frequency when the rotation speed becomes lower is generated. The light emitting element is pulse-lit based on the pulse thus obtained.

[0011]

1 (a) is a sectional view showing the structure of a multi-rotation absolute type rotary encoder according to an embodiment of the present invention, and FIG. 1 (b) is a front view showing its rotary plate.
As shown in these figures, the rotary encoder has a rotating shaft 4 rotatably held by bearings 2 and 3 in a case 1. The rotary plate 5 is fixed to the rotary shaft 4. As shown in FIG. 1B, different predetermined patterns are formed on the rotary plate 5 along a plurality of concentric circles corresponding to the angles. As this pattern, a pattern as shown in the drawing is formed corresponding to a Gray code in which the Hamming distance between the minimum resolutions is 1 with the number of bits according to the resolution of rotation. In this figure, the slit 5a is the uppermost (MSB) slit, and the slit 5b is the MSB-1 slit. In this way, a large number of slits from MSB to LSB are sequentially formed on the inner peripheral side. If the number of concentric circles of this slit is 12, one rotation can be detected with a resolution of 2 ¹² .

A plurality of light emitting elements, for example, light emitting diodes 6a to 6d are provided at positions corresponding to the slits. A fixed slit plate 7 and a plurality of photodiodes 8a to 8l are provided corresponding to this light emitting diode. Here, the light emitting diodes 6a to 6d irradiate the positions corresponding to the photodiodes 2 to 4, respectively.

2 to 4 are circuit diagrams showing the circuit configuration of the rotary encoder according to this embodiment. In FIG. 2, a voltage detection circuit 11 is connected to a power supply terminal + V externally supplied to the rotary encoder, and a constant voltage circuit 12 for stabilizing the voltage is provided. The constant voltage circuit 12 is provided with a diode for preventing backflow so that current does not flow from the output side.

The output side of the constant voltage circuit 12 is connected to a ground terminal with a built-in battery 13 such as a lithium battery for continuing a part of the operation even when the power is off, via a resistor and a diode. ing. A reset circuit 14 is connected to the output side of the constant voltage circuit 12. Now, the power input terminal 1
Three light emitting diodes 6b to 6d are connected in series to 0 via a transistor Q1 and are grounded. The voltage at the power input terminal 10 is also given to the clock generation circuit 15.
The clock generation circuit 15 is a circuit that supplies a signal of a constant high frequency, for example, a clock frequency of 4 MHz to each part of the rotary encoder, and is configured by using, for example, a crystal oscillator.

A light emitting diode 6a is connected to the output + V _B of the constant voltage circuit 12 via a transistor Q2. The output of the voltage detection circuit 11 is given to the base of the transistor Q1 via the inverter 16. The transistor Q1 turns on the three light emitting diodes 6b to 6d by the power source of the power source input terminal 10 only when an output is obtained from the voltage detection circuit 11. The output terminal + V _B of the built-in battery 13 is used as a power source for the pulse generation circuit 17 and the gate circuits 18 to 20 and the comparators 21a and 21b of FIG.
... is also connected to. The pulse frequency of the pulse generating circuit 17 is manually set according to the rotation speed of the rotary shaft 4 of the rotary encoder when the power is turned off. For example, when the power is off, the rotating shaft 4 has a maximum of 4rp
If there is a possibility of s rotation, and pulse lighting is performed four times per rotation, the pulse generation circuit 17 outputs a pulse LDC of 20 Hz. This output is applied to the base of transistor Q2 via gate circuits 18-20. If the gate circuit 18 is a NOR circuit, the output of the voltage detection circuit 11 is given to the other input terminal. When the output of the voltage detection circuit 11 is at H level, the light emitting diode 6a is continuously turned on. Then, as shown in FIG. 3, photodiodes 8a and 8b are provided corresponding to the light emitting diode 6a via a fixed slit plate 7 and a rotary plate 5.
Are connected. Other photodiodes 8c to 8l are connected to the light emitting diodes 6b, 6c, 6d. Each of the photodiodes 8a to 8l receives an optical signal obtained through the slit of the rotary plate 5, and
The output is given to the comparison circuits 21a to 21l. The comparison circuits 21a to 21l output the presence / absence of a light reception signal by shaping the waveforms of these outputs, and the outputs thereof are given to the code conversion circuit 22. The code conversion circuit 22 converts a 12-bit gray code signal from MSB to LSB into a binary code and outputs it as a 12-bit signal corresponding to the rotation angle of the rotary shaft 4. This structure is the same as that of a normal absolute type rotary encoder. Here, the comparison circuit 21a-
21l and the code conversion circuit 22 constitute a rotation angle detecting means for detecting the rotation angle of the rotation shaft based on the parallel output of the light receiving elements.

The outputs of the gray code MSB and MSB-1 obtained from the comparison circuits 21a and 21b are given to the D-type flip-flops 23a and 23b, respectively, as shown in FIG. Further, the output SYSCLK of the clock generation circuit 15
The output LDC of the pulse generation circuit 17 is supplied to the clock selection circuit 24. The clock selection circuit 24 selects one of the clocks based on the output LDCMODE of the voltage detection circuit 11. The selected output is applied to the clock input terminals of the D-type flip-flops 23a and 23b via the inverter 25 and to the clock input terminals of the D-type flip-flops 27 and 37 via the inverter 26. The D-type flip-flops 23a and 23b synchronize the two bits of MSB and MSB-1 with the selected clock. The D-type flip-flop 27 delays the output of the flip-flop 23a by one clock, and its output is given to the EOR circuit 28. The EOR circuit 28 is a D-type flip-flop 23a, 2
The exclusive OR of 7 and its output is given to the AND circuit 29. The AND circuit 29 takes a logical product with the Q-bar output of the D-type flip-flop 23b, and its output is given to the AND circuits 30 and 31.
The AND circuit 30 sets the RS flip-flop 32 by the logical product with the Q-bar output of the D-type flip-flop 23a. Further, the AND circuit 31 is the AND circuit 2.
The RS flip-flop 32 is reset via the OR circuit 33 by the logical product of the output of 9 and the Q output of the D-type flip-flop 23a. In addition, the reset circuit 14
The reset signal RST is configured to reset the RS flip-flop 32 via the inverters 34 and 35 and the OR circuit 33. RS flip-flop 3
Reference numeral 2 is for discriminating either the forward direction or the backward direction based on the order of outputs of the MSB and MSB-1 and giving an up-count or down-count signal to the up-down counter 36.

On the other hand, the output of the AND circuit 29 is given to the counter 36 via the D-type flip-flop 37. The D-type flip-flop 37 provides the input signal of the counter 36 in synchronization with the clock. This counter 36
Is D based on the 2-bit output of MSB and MSB-1.
The up / down counter holds the rotation speed by counting up or down the output of the type flip-flop 37. Here, the D-type flip-flop 23
The a, 23b and 27, the EOR circuit 28 and the AND circuit 29 constitute a rotation detecting means 38 which detects one rotation of the rotary plate 5 based on the outputs of MSB and MSB-1. Further, the D-type flip-flop 23a, the AND circuits 30 to 33, and the RS flip-flop 32 constitute a rotation direction detecting means 39 for detecting the rotation direction of the rotary plate 5 based on the light receiving signals of MSB and MSB-1. The counter 36 detects and holds the number of rotations, and the built-in battery 13 shown in FIG. 2 or another built-in battery is configured to always hold the count value.

Next, the operation of this embodiment will be described with reference to the time chart of FIG. 5 (a) to 5 (m) show the waveforms of the respective parts of FIG. First, when the power is turned on, the output of the voltage detection circuit 11 is at the H level,
The three light emitting diodes 6b through the transistor Q1
6d lights continuously. Also, because of this output, the output of the NOR circuit 18 is always at the L level.
The light emitting diode 6a is continuously lit via the LED 2. The clock generation circuit 15 generates the clock signal SYSCLK at a high constant frequency, and the clock selection circuit 24
Is supplied as a clock signal to each unit via. Therefore, when the rotary shaft 4 of the rotary encoder rotates in the forward direction, the photodiodes 8a and 8b are rotated according to the rotation.
... outputs intermittent output, and comparison circuits 20, 21 ...
・ The signal corresponding to the rotation angle is output by. This Gray code signal is converted into a binary code by the code conversion circuit 22 shown in FIG. 3, and the rotation angle signal of the rotation shaft 4 is obtained.

The outputs of the comparison circuits 21a and 21b are added to the D-type flip-flops 23a and 23b, respectively, as shown in FIG.
As shown in (e) and (f), an output synchronized with the clock signal is obtained. Then, a signal delayed by one clock from the output of the D-type flip-flop 23a is obtained from the D-type flip-flop 27 as shown in FIG. 5 (g), and as shown in FIG. 5 (h) by their exclusive OR. A pulse is obtained. While the Q-bar output of the D-type flip-flop is H while this pulse is obtained, an AND signal is output from the AND circuit 29 and is counted by the counter 36 via the D-type flip-flop 37. The AND circuits 30 to 33 determine the order in which this output is obtained. Since the RS flip-flop 32 is set in the normal rotation, the Q output causes the counter 36 to count up. In this way, one rotation at the time of forward rotation is shown in FIG.
MSB and MSB-1 are 1 as shown in (c) and (d).
Since the cycle changes, the number of rotations corresponding to the rotation can be counted.

Now, if the power is turned off at time t ₁ , as shown in FIG.
As shown in (a), the output of the voltage detection circuit 11 becomes L level, and the light emitting diodes 6b to 6d are turned off. Further, the clock of the clock generation circuit 15 is also stopped. At this time, the pulse generator circuit 17 is operated by the power source from the built-in battery 13, and the low frequency pulse LDC is output. This output intermittently drives the transistor Q2 via the gate circuits 18 to 20, so that the light emitting diode 6a is pulse-lighted. Therefore, as shown in FIG. 5C, outputs are intermittently obtained from the comparison circuits 21a and 21b. This output causes the D-type flip-flops 23a and 23b to operate.

[0021] Now is the time t ₂ reduces the rotational force from the outside, it is assumed that the rotary plate 5 is stopped. Then, the output of the MSB or MSB-1 is determined according to the rotation angle, but the output does not change. Next, if it is assumed that the rotating plate 5 starts to rotate in the opposite direction at time t ₃ , the light emitting diode 6a is similarly pulse-lighted in the power-off state.
Here, when the light emitting diode 6a is continuously lit, the output as shown by the broken line in FIG. 5C is obtained. However, because of the pulse lighting, only the signal at the time corresponding to lighting is obtained. By synchronizing this signal with the clock signal by the D-type flip-flops 23a and 23b, outputs as shown in FIGS. 5E and 5F are obtained. In this case, since the phases of MSB and MSB-1 are opposite to the normal rotation, the RS flip-flop 32 is always reset and the down-count signal is given to the counter 36. Then, for each output of the AND circuit 29, an output synchronized with the clock signal is added to the counter 36 by the D-type flip-flop 37, and the count value of the counter decreases every one rotation. Therefore, the counter 36 can maintain the rotation speed even when the power is off.

As described above, in the present embodiment, among the light emitting diodes for projecting light, the light emitting diodes for irradiating the upper bits are pulse-lighted even when the power is off, so that the number of revolutions when the power is off can be detected. . Therefore, the speed reduction mechanism is unnecessary, and the magnetic rotating plate and the like are also unnecessary. Furthermore, since the change point of one rotation of the rotating plate and the minimum change angle of rotation automatically match, the number of rotations can be changed accurately at the origin position like the conventional multi-rotation absolute rotary encoder. No need for adjustment work.

Next, a second embodiment of the present invention will be described. In the first embodiment, as soon as the power supply voltage is turned off, L
The light emitting diode 6a is pulse-lighted at a low frequency by the output of the pulse generation circuit 17 according to the DCMODE signal. However, when this rotary encoder is attached to the shaft of a motor that rotates at a high speed, it may continue to rotate at a relatively high rotation speed for a certain period of time due to inertia even immediately after the power is turned off. In such a case, if the light emitting diode 6a is immediately pulse-lighted, the rotation speed cannot be counted if the rotation speed is high. Therefore, in the second embodiment, the light emitting diode 6a is continuously turned on for a certain period of time after the power is turned off.

FIG. 6 shows a portion for generating a mode signal for setting the operation mode based on the output of the voltage detection circuit of FIG. 2 in the second embodiment. Other configurations are similar to those of the first embodiment, and detailed description thereof will be omitted.
In FIG. 6, the output of the voltage detection circuit 11 is given to the inverter 41 of the delay circuit 40. The inverter 41 inverts the output of the voltage detection circuit 11, and its output is the resistance R
It is given to the inverter 42 via 1 and R2. Resistance R
The capacitor C1 is connected between the common connection point of the inverter 2 and the inverter 42 and the ground terminal. A diode D1 is connected in parallel to both ends of the resistor R2. This delay circuit 40
Is an off-delay type delay circuit in which the charge stored in the capacitor C1 is gradually discharged when the output of the voltage detection circuit 11 becomes L level, and for example, the LDMODE signal is inverted after a delay time of about 1 second. By doing so, the light emitting diode 6a is continuously turned on during the delay time, and it is possible to cope with the high speed rotation of the encoder due to the inertia immediately after the power is turned off, and the number of rotations can be accurately counted.

Next, a third embodiment of the present invention will be described. In this embodiment, the power supplies of the comparison circuits 21a and 21b are intermittently turned on and off according to the output of the pulse generation circuit 17 to reduce the current consumption when the power supply of the comparison circuit is off. Other configurations are similar to those of the first embodiment. In this embodiment, the synchronizing signal generating circuit 43 is provided on the output side of the gate circuit 19. The synchronization signal generation circuit 43 has inverters 44 and 45 that are connected in series as shown in FIG. 6, and on the output side of the inverter 44, a capacitor C2 is connected to the ground terminal and a resistor R3 is connected to the power supply. Are connected. Then, the output of the inverter 45 is compared circuit 21 shown in FIG.
It is used as a power supply VCOMP of a and 21b. By doing so, when the output of the gate circuit 19 is at the H level, the light emitting diode 6a is passed through the inverter 20 and the transistor Q2.
Is energized and lights up. At this time, at the same time, power is supplied to the comparison circuits 21a and 21b by the output of VCOMP to operate. Therefore, the outputs of the MSB and MSB-1 of the comparison circuit are given to the logic circuit section shown in FIG. 4 only during the pulse lighting period in which the operation is required. Since the current consumption of the comparison circuits 21a and 21b is relatively large, the current consumption can be significantly reduced by performing such an intermittent operation, and the built-in battery 13 can have a long life.

Next, a fourth embodiment of the present invention will be described. In this embodiment, the pulse frequency of the pulse generating circuit 17 is changed. Pulse generation circuit 17
Since the configuration other than the above is the same as that of the first embodiment described above, the description thereof will be omitted. FIG. 7 shows the pulse generation circuit 1 of this embodiment.
It is a circuit diagram which shows the structure of 7A. In this pulse generation circuit, a plurality of inverters are connected in cascade, a feedback loop is formed by the resistor R4 and the capacitor C3, and a variable resistor VR1 is provided in the feedback loop to change the cycle of the generated pulse. The signal thus obtained is applied to the monostable multivibrator 46. The monostable multivibrator 46 changes the pulse width of the generated signal by the variable resistor VR2. The output thus obtained is supplied as LDC to the NOR circuit 18 of FIG. 2 and to the clock selection circuit 24 of FIG. 4 as described above. In this way, the pulse generation circuit 17
The frequency and pulse width can be selected. In this way, when the rotating shaft is externally biased to rotate when the power is turned off, by setting the frequency according to the maximum number of rotations, it is possible to select the minimum necessary frequency, and the built-in battery 13 can be selected. The life can be extended.

Next, a fifth embodiment of the present invention will be described. In this embodiment, the pulse cycle of the pulse generating circuit can be selected according to the rotation speed of the rotary plate 4 when the power is off. In this embodiment, the pulse generating circuit shown in FIG. 8 is used in place of the pulse generating circuit shown in FIG.
The other structure is similar to that of the first embodiment, and the description thereof is omitted. In FIG. 8, the outputs of the comparison circuits 21a and 21b are also given to the D flip-flops 51a and 51b. The D-type flip-flops 51a and 51b operate on the basis of the pulse output LDC to synchronize the output of the comparison circuit with the pulse signal. The output is the change point detection circuit 5 of the rotation speed detection means 52.
Given to 3. The change point detection circuit 53 detects a change point of rising or falling of the outputs of the D-type flip-flops 51a and 51b, and outputs a detection signal to the rotation speed counter 54 and the rotation speed determination circuit 56 of the LEDCK generation means 55. give. The LEDCK generation means 55 has an LEDCK
A generation circuit 57 is provided. The LEDCK generation circuit 57 is a generation circuit that generates, for example, six kinds of pulses whose cycle changes every four times, for example, 40 Hz, 10 Hz, 2.5 Hz, 0.625 Hz ... Pulses, and each output thereof is a multiplexer (MPX). ) 58. The multiplexer 58 selectively selects this pulse, and the selected output is used as the light projecting pulse LDC to the gate circuit 1 of the first embodiment.
8 to 20 and is added to the transistor Q2. This pulse signal is also sent to the D-type flip-flop 5 at the same time.
1a, 51b and the logic circuit shown in FIG.

The rotation speed counter 54 is a counter that counts the pulses selected by the multiplexer 58 and is reset according to the detection signal of the change point detection circuit 53, and the count output is given to the rotation speed determination circuit 56. . The rotation speed determination circuit 56 determines the value immediately before the rotation speed counter 54 is reset each time a change point is detected by the change point detection circuit. If the count value is, for example, 2 or less, an up-count output, 16 or more is output. For example, the down count output is given to the up / down counter 59. The up / down counter 59 is an up / down counter that operates according to this signal, and its count output is given to the multiplexer 58. The multiplexer 58 selects the higher frequency of the LEDCK generation circuit 57 when the count value of the counter 59 decreases, and selects the clock pulse of the lower frequency when the count value increases.

Next, the operation of this embodiment will be described. FIG. 9 is a time chart showing the operation of this embodiment. Figure 9
(A)-(h) has shown the waveform or count value of each part of FIG. First, when the power is off, the clock of the clock generation circuit 15 is stopped as in the first embodiment. If the rotary shaft 4 is rotationally driven from the outside even when the power is off, the comparison circuits 21a, 2a of the absolute encoder
An output is obtained from 1b, whereby the outputs of the D-type flip-flops 51a and 51b become those shown in FIGS. 9 (a) and 9 (b). At this time, the pulse selected by the multiplexer 58 is the pulse shown in FIG. The pulses are sequentially counted by the rotation speed counter 54 as shown in FIG. 9D, and the change point detection circuit 53 changes the output of the D-type flip-flops 51a and 51b as shown in FIG. 9E. It is detected as shown. The rotation speed counter 54 is reset each time this detection is performed. Now, at time t ₂ , the rotation speed counter 54 becomes 16
Is counted, the rotation number discriminating circuit 56 gives an up-count output to the counter 59 as shown in FIG. Therefore, the counter 59 counts up, and the count value increases from N to N + 1 as shown in FIG. 9 (h). As the count value of this counter increases, a pulse lower than that of the LEDCK generation circuit 57 is selected by the multiplexer 58, and a pulse having a cycle four times the original pulse is selected as shown in FIG. 9C. It This is 1 /
This is because, when projecting 16 pulses for two rotations, the number of projected beams is too large and the internal battery may be consumed early, and the number of pulses is reduced.

As shown in FIG. 9 (c), it is assumed that the rotation shaft continues to be rotated continuously from the outside even after the period is lengthened. If the count value immediately before the rotation speed counter 54 is reset is 4 or 3, the output is not transmitted to the up / down counter 59 and the original count value is held. Then, the number of rotations of the rotary shaft 4 increases, and
As shown in (b), if the inversion cycle of the MSB or MSB-1 becomes short, the count value of the rotation speed counter 54 becomes 2 or less at the time of detecting the change point, as shown in the figure. Time in this case
As shown at t ₃ , the change point of the MSB-1 is the change point detection circuit 5
3, the rotation speed is determined at that time, and the down count output is output as shown in FIG. 9 (g). Therefore, the up / down counter 59 down-counts the count value as shown in FIG. 9 (h), and the count value becomes the original N. As a result, the pulse period returns to the original state as in the period between times t _{1 and} t ₂ . By repeating such an operation, it is possible to automatically select the frequency of the pulse according to the rotation speed of the rotating shaft at that time.

FIG. 10 shows the relationship between the rotational speed of the encoder and the frequency of the selected pulse LDC and the relationship of the consumed current when the power is off. As is apparent from FIGS. 10A and 10B, if the rotation speed of the encoder from the outside increases, the pulse frequency corresponding to the rotation speed is selected. Even if the pulse frequency is low, the logic circuit or the like consumes a substantially constant current, so that the change in the consumed current is as shown in FIG. As described above, when the power is off, the lighting frequency of the pulse is determined according to the rotation speeds of the rotary shaft 4 and the rotary plate 5, so that the current consumption can be reduced.

In this embodiment, the rotation speed is detected based on the outputs of the comparison circuits 21a and 21b, but it may be detected by only one of the outputs. If the power is supplied to each comparison circuit from the built-in battery when the power is off, the rotation speed may be detected by using the output of any one of the comparison circuits.

Also in this embodiment, a delay circuit for delaying the output of the voltage detection circuit is provided immediately after the power is turned off, or the power is supplied to the comparison circuit in synchronization with the output of the LEDCK generating means. You can also

Further, in each of the above-mentioned embodiments, the four light emitting diodes 6a to 6d are used to irradiate light to the light receiving elements 2 to 4, respectively, and only the light emitting diodes corresponding to MSB and MSB-1 are turned on and off. ing. However, apart from the first light-emitting diode for continuous lighting, a second light-emitting diode that is driven according to the pulse signal LDC from the pulse generating circuit is independently provided only when the power is off, and this light is supplied to the MS.
The light receiving elements 8a and 8b of B and MSB-1 may be irradiated. It is also possible to provide a single light emitting diode and use a cylindrical lens or the like to irradiate each light receiving element with light through a slit. Further, in each of the above-described embodiments, the battery is built in the encoder,
It goes without saying that a battery connected in the same manner as this may be provided outside.

[0035]

As described in detail above, according to the present invention, the number of revolutions can be accurately changed at the angle at which the MSB changes when the power is turned on, and the minimum of the multi-rotation absolute rotary encoder. The rotation speed can be changed corresponding to the change point of the resolution. Therefore, unlike a conventional multi-rotation absolute encoder, a reduction mechanism and a plurality of rotating plates are not used, so that the size and cost can be reduced. Further, even when compared with the conventional multi-rotation absolute rotary encoder in which the rotary plate and the magnetic rotary plate are connected, a change in the rotation angle for one bit and a change point in the rotation number after one rotation are produced during manufacturing. Since it is not necessary to match them, precise alignment is not necessary, and manufacturing can be performed extremely easily.

Further, in the inventions of claims 4 and 10 of the present application, the light emitting diode is continuously lit by the delay circuit even if the rotary shaft rotates at high speed due to inertia immediately after the power is turned off. Can be reliably detected. Further, in the inventions of claims 5 and 11, power consumption can be significantly reduced by intermittently operating the comparison circuit when the power is off. Further, according to the invention of claim 6, it is possible to reduce unnecessary battery consumption by selecting a pulse frequency corresponding to the maximum speed of the number of revolutions applied from the outside when the power is turned off.

Further, in the invention of claim 7 of the present application, the rotational speed applied from the outside when the power is turned off is automatically detected by the rotational speed detecting means, and the pulse frequency is selected based on this. Therefore, even when the rotation speed becomes high, the number of rotations can be surely counted by increasing the pulse frequency. Further, when the number of rotations becomes low or stops, the pulse frequency can be made low, so that the excellent effect that the current consumption can be greatly reduced can be obtained.

[Brief description of drawings]

FIG. 1A is a sectional view showing the structure of a multi-rotation absolute rotary encoder according to an embodiment of the present invention,
(B) is a front view showing the rotary plate.

FIG. 2 is a block diagram showing a configuration of a main circuit portion of the rotary encoder according to the first embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of a rotation angle detecting means of the present embodiment.

FIG. 4 is a block diagram showing a configuration of a rotation speed detection means and a rotation direction detection means of this embodiment.

FIG. 5 is a time chart showing the operation of the first embodiment of the present invention.

FIG. 6 is a circuit diagram showing a configuration of a main part of a rotary encoder according to second and third embodiments of the present invention.

FIG. 7 is a circuit diagram showing a configuration of a pulse generation circuit according to a fourth embodiment of the present invention.

FIG. 8 is a block diagram showing a configuration of a rotation speed detection means and an LEDCK generation means according to a fifth embodiment of the present invention.

FIG. 9 is a time chart showing the operation of the fifth embodiment of the present invention.

FIG. 10 is a graph showing a relationship among a rotation speed, a pulse frequency and a consumption current according to a fifth embodiment of the present invention.

FIG. 11 is a perspective view showing a main part of a conventional multi-rotation absolute rotary encoder.

FIG. 12 is a diagram showing a main part of another conventional multi-rotation absolute rotary encoder.

[Explanation of symbols]

 1 Case 4 Rotating shaft 5 Rotating plate 6a-6d Light emitting diode 7 Fixed slit plate 8a-8l Photodiode 11 Voltage detection circuit 12 Constant voltage circuit 13 Built-in battery 14 Reset circuit 15 Clock generation circuit 17, 17A Pulse generation circuit 21a, 21b. .. 21l Comparing circuit 23a, 23b, 27, 37 D-type flip-flop 24 Clock selection circuit 32 RS flip-flop 36 Counter 38 Rotation detecting means 39 Rotation direction detecting means 40 Delay circuit 43 Synchronous signal generating circuit 52 Rotation speed detecting means 53 Change Point detection circuit 54 Rotational speed counter 55 LEDCK generation means 56 Rotation determination circuit 57 LEDCK generation circuit 58 Multiplexer 59 Counter

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Shinichi Yamamoto, No. 10 Hanazono Dodo-cho, Ukyo-ku, Kyoto City, Kyoto Prefecture Omron Co., Ltd. (72) Inventor Shinsuke Asami No. 10 Hanazono Todo-cho, Kyoto, Kyoto City Within the corporation

Claims (11)

[Claims] 1. A rotary plate, which is connected to a rotary shaft and has slits of different patterns formed along a plurality of concentric circles corresponding to a rotation angle, and a light-projecting element for projecting light to the rotary plate, The comparison circuit includes a plurality of light receiving elements that receive the light of the light projecting element through the slits of the rotary plate, and a plurality of comparison circuits that discriminate parallel outputs obtained from the plurality of light receiving elements with a predetermined threshold value. Rotation angle detecting means for detecting the rotation angle of the rotating shaft according to the parallel output of the clock, a clock generating circuit for generating a predetermined clock when the power is turned on, and a light receiving signal of MSB, MSB-1 among the light receiving elements. Rotation detecting means for detecting one rotation of the rotating plate based on the rotation direction; rotating direction detecting means for detecting a rotating direction of the rotating plate based on light receiving signals of MSB and MSB-1 among the light receiving elements; A counter that counts the output of the rotation detection means in either an up direction or a down direction according to the output of the output means, a pulse generation circuit that generates a pulse for lighting the light projecting element, and a power supply when the power is turned on. A light projecting element driving means for continuously lighting the light projecting element and for lighting the light projecting element in a pulsed manner based on the output of the pulse generating circuit when the power is turned off, the pulse generating circuit, the rotation detecting means, and the rotation direction detection. Means, a battery for supplying power to the light emitting element driving means and the counter, and an output of the pulse generating circuit and the clock generating circuit according to the interruption of the power source, and the rotation detecting means and the rotation direction detecting means. And a clock selection means for giving
A multi-rotation absolute rotary encoder, wherein a rotation angle is detected by the rotation angle detecting means and a rotation speed is detected by the counter. 2. The light projecting element is composed of a plurality of light projecting elements, and the light projecting element driving means irradiates light to a light receiving element which detects MSB, MSB-1 among the light receiving elements when the power is off. 2. The multi-rotation absolute type rotary encoder according to claim 1, wherein only the light projecting element is pulse-lit. 3. The light projecting element is continuously turned on when the power is turned on, and the first light projecting element that irradiates the plurality of light receiving elements with light is pulsed when the power is turned off.
2. The multi-rotation absolute type rotary encoder according to claim 1, further comprising a second light projecting element for irradiating the light receiving element with light. 4. A voltage detection circuit for detecting the on / off state of the power supply voltage, and an off-delay type delay circuit for delaying a power-off signal of the voltage detection circuit for a predetermined time. The multi-rotation absolute type rotary encoder according to any one of claims 1 to 3, wherein the output of the pulse generation circuit is selected based on the output of the delay circuit. 5. A synchronizing signal that is synchronized with the output of the pulse generating circuit is generated, and the MSB, MSB-
The multi-rotation absolute type rotary encoder according to any one of claims 1 to 4, further comprising a synchronization signal generation circuit that supplies power to a comparison circuit that generates one light reception signal. 6. The multi-rotation absolute rotary encoder according to claim 1, wherein the pulse generation circuit has a variable means for varying its frequency and pulse width. 7. A rotary plate connected to a rotary shaft and having slits of different patterns formed along a plurality of concentric circles corresponding to rotation angles, and a light projecting element for projecting light to the rotary plate, The comparison circuit includes a plurality of light receiving elements that receive the light of the light projecting element through the slits of the rotary plate, and a plurality of comparison circuits that discriminate parallel outputs obtained from the plurality of light receiving elements with a predetermined threshold value. Rotation angle detecting means for detecting the rotation angle of the rotating shaft according to the parallel output of the clock, a clock generating circuit for generating a predetermined clock when the power is turned on, and a light receiving signal of MSB, MSB-1 among the light receiving elements. Rotation detecting means for detecting one rotation of the rotating plate based on the rotation direction; rotating direction detecting means for detecting a rotating direction of the rotating plate based on light receiving signals of MSB and MSB-1 among the light receiving elements; A counter that counts the output of the rotation detecting means in the up direction and the down direction according to the output of the outputting means, and a rotation speed detecting means that detects the rotation speed based on the comparison output of the light receiving signals of any one of the light receiving elements. LEDCK generating means for generating a pulse having a frequency corresponding to the rotation speed detected by the rotation speed detecting means, the light emitting element is continuously turned on when the power is turned on, and the light emitting element is operated by the LEDCK when the power is turned off. A light projecting element driving means for lighting a pulse based on the output of the generating means, a power source for the rotation speed detecting means, the LEDCK generating means, the rotation detecting means, the rotation direction detecting means, the light projecting element driving means and the counter. The battery for supplying the power, and the output of the LEDCK generating means and the clock generating circuit are selected according to the on / off of the power source to detect the rotation. Comprising a clock selecting means for providing the step and the rotation direction detection means, the rotation angle by the rotation angle detecting means, a multi-rotation absolute-type rotary encoder and detects the rotation speed by the counter. 8. The light projecting element comprises a plurality of light projecting elements, and the light projecting element driving means irradiates light to a light receiving element for detecting MSB, MSB-1 among the light receiving elements when the power is off. 8. The multi-rotation absolute type rotary encoder according to claim 7, wherein only the light projecting element is pulse-lit. 9. The light projecting element is continuously lit when the power is turned on, and the first light projecting element that irradiates the plurality of light receiving elements with light is pulse-lighted when the power is off. The MSB, MSB-1
8. A multi-rotation absolute rotary encoder according to claim 7, further comprising: a second light projecting element that irradiates the light receiving element with light. 10. A voltage detection circuit for detecting ON / OFF of a power supply voltage, and an off-delay type delay circuit for delaying a power-off signal of the voltage detection circuit for a predetermined time. The LED based on the output of the delay circuit
10. The multi-rotation absolute type rotary encoder according to claim 7, wherein the output of the CK generating means is selected. 11. A comparison circuit that has a synchronization signal generation circuit that generates a synchronization signal that synchronizes with the output of the LEDCK generation means, and that generates a light reception signal of the MSB, MSB-1 by the output of the synchronization signal generation circuit. The multi-rotation absolute type rotary encoder according to any one of claims 7 to 10, wherein power is supplied.