JPH07190810A - Rotary encoder and input device using the rotary encoder - Google Patents

Abstract

PURPOSE:To obtain a rotary encoder or the like which can dispense with adjustment and is fit to be formed in an IC, by providing a first and a second comparators, a peak hold circuit and a reference value-generating circuit. CONSTITUTION:Outputs from load resistances Ra, Rb are turned to A+B phase signals at an adder/subtracter circuit 1 and sent to comparators 16, 17. An operational amplifier 3 treats each level of signals by an addition/subtraction process when receiving the A+B phase signal synthesized at a signal- synthesizing circuit 2 and a subtraction voltage value from a subtraction voltage value-generating circuit 4, thereby generating a signal of an A+B phase almost equal to an A phase of an amplitude reference level. The circuit 4 is constituted of a peak hold circuit. and a reference value-generating circuit. A subtract.ion amount is generated at the peak hold circuit and reference value-generating circuit so as to return an amplitude reference of the A+B phase signal to the amplitude reference of the original A-phase or B-phase signal. Since a variable resistance and a capacitor are not included in a detecting circuit of the rotary encoder, the rotary encoder is suitable to be formed into an IC and becomes a circuit dispensing with adjustment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary encoder, and more specifically, it is incorporated in a mouse or a trackball used in a personal computer, a workstation or the like, and its movement amount or operation amount (hereinafter, represented by movement amount) is represented. The present invention relates to a rotary encoder used as a sensor that detects a rotation amount.

[0002]

2. Description of the Related Art Usually, a mouse or a trackball comprises a ball and a roller that frictionally engages with the ball to detect the amount of movement in the X-axis direction, and the rotation of the roller is detected by a rotation amount detector such as a rotary encoder. An X-axis sensing mechanism for detecting and a Y-axis sensing mechanism for detecting a movement amount in the Y-axis direction by rotation of a roller in the Y-axis direction with a similar detector are built in. FIG. 5 is an explanatory diagram of a detector portion using a rotary encoder for the X-axis or Y-axis sensing mechanism. Reference numeral 10 is a detector, and 12 is a disk fixed to a rotary shaft 11 of a roller that frictionally engages with a ball built in a mouse or a trackball, and is provided with a large number of radial slits to rotate the ball. Rotates in conjunction with.

Reference numeral 13 denotes a light emitting diode, which is a disk 12
The light-receiving elements (phototransistors) 14 and 15 provided on the opposite side are irradiated with the emitted light through the slit 12a. The light receiving elements 14 and 15 are arranged inside one light receiver, and the arrangement makes the light of the light emitting diode 13 slit 1.
When light is received via 2a, signals having phases of approximately 90 ° are generated depending on the light receiving position. Each light receiving element is composed of a phototransistor, its collector side is connected to the power supply line Vcc, and its emitter side is grounded via variable resistors R1 and R2. The detection signals obtained from the respective light receiving elements 14 and 15 having a phase difference of 90 degrees are taken out from the variable resistors R1 and R2 as voltage signals of A phase and B phase, respectively, and input to the comparators 16 and 17 of the encoder 18. .

In the case where two phototransistors are built in one light receiver, the signal photoelectrically converted here is such that the two phototransistors receive light sequentially and the light emitted to each phototransistor is , Increases gradually with the rotation of the disk 12, reaches a maximum, and decreases. Therefore, the detection signal does not have a rectangular waveform but a voltage signal waveform that is almost a sine wave. Therefore, each voltage signal is waveform-shaped by the comparators 16 and 17 of the encoder 18 into two detection pulses of A phase and B phase. These A-phase and B-phase detection pulses are then input to the logic circuits from the comparators 16 and 17, respectively, encoded into pulse signals in the X direction or the Y direction, or converted into predetermined pulses and processed by a computer or the like. It is sent to the body side. At this time, the variable resistors R1 and R2 are used in order to absorb the difference in the characteristics of the two phototransistors, but these are arranged by arranging a plurality of resistors and selecting an optimum resistor from them. However, the optimum resistance value may be selected by cutting the wiring of a plurality of resistors.

[0005]

The detection pulse is often counted and pulse-converted according to the timing relationship between the rising and falling edges of the A-phase and B-phase signals. Is preferably 90 degrees and the duty is 50%. However, in the detector of the conventional rotary encoder of this type, the amplitude of the detection signal fluctuates due to variations in the characteristics of the light emitting element of the light emitting diode and the sensitivity of the phototransistor. As a result, the waveform of the detection pulse changes and the phase relationship becomes inaccurate, so the level of the output signal of each light receiving element is adjusted by the variable resistors R1 and R2. Therefore, it is difficult to make no adjustment with this type of rotary encoder.

FIG. 6 shows an unadjusted circuit of this type. Further provided between the light receiving element and the comparator are comparators 19 and 20 for shaping the waveform of the signal with the average value of the output signal of the light receiving element as a reference level. On the reference level side of the comparators 19 and 20 as a circuit for generating an average value, integrating circuits 19a and 2a composed of resistors and capacitors are provided.
0a is provided. As a result, the duty is almost 50
% Pulse is obtained, but the phase difference is affected by the level of the output signal of each light receiving element and has a drawback of lacking accuracy. In addition, this type of circuit requires capacitors, which makes it difficult to form an IC and has the drawback of increasing the circuit scale. An object of the present invention is to solve the above-mentioned problems of the prior art, and it is possible to generate a detection pulse having a phase difference of approximately 90 ° by an unadjusted circuit, and to provide a rotary encoder suitable for IC implementation. It is an object to provide an input device using this.

[0007]

The features of the rotary encoder of the present invention and the input device using the same for achieving the above-mentioned object are that the light from the light emitting element is transmitted through the slit formed in the rotating disk. And a light receiving device having first and second light receiving elements for generating detection signals of substantially sinusoidal waves whose phases are different from each other by 90 ° and receiving the outputs of the first and second light receiving elements. Of the analog-added signal from which a predetermined reference value is subtracted and output, or an amplifier circuit that generates an output approximate to this, and an output of this amplifier circuit that receives the output of the first light-receiving element A first comparator which receives the other input and compares them, and a second comparator which receives the output of the amplifier circuit in one input and receives the output of the second light receiving element in the other input and compares them , First A peak hold circuit for holding the peak value in response to a signal from the light receiving element is one and a reference value generating circuit for generating the reference value from the hold value of the peak hold circuit.

[0008]

The signal obtained from each light receiving element of the rotary encoder has an analog waveform close to a sine wave.
Since there is a phase difference between the A phase and the B phase, the A + B phase signal added with the A phase and B phase signals exceeds the peaks of the positive and negative A phase and B phase signals (negative side). Values smaller than those peaks) and shift from positive to negative or vice versa from A phase peak to B phase peak or from B phase peak to A phase peak. In between, the value between each signal value is taken.

Therefore, as described above, by comparing the A + B-phase signal obtained by adding the A-phase and B-phase signals with each phase signal, the comparison of the A phase signal with the A phase positive side is performed. Since the signal level of the A phase is exceeded between the time when the peak is exceeded and the peak of the negative side of the A phase, the A phase detection pulse is reliably generated. Similarly, in comparison with the B phase signal, the B phase signal is detected. The signal level of the B phase is lower than the level of the signal on the positive side of B to the peak of the B phase on the negative side.
A phase detection pulse can be generated. Where A +
When the B-phase signal is generated by the addition processing, an offset also occurs in the signal that is added and synthesized due to the offset of the A-phase and B-phase signals due to the dark current, and the amplitude-based potential of the A + B-phase signal shifts. In order to correct this, the peak value (maximum value) of one signal is held and the subtraction amount is used to restore the amplitude reference of the A + B phase signal to the original amplitude reference of the A phase or B phase signal from the peak value. Generate. The peak hold circuit and the reference value generation circuit do this. Therefore, if the first light receiving element is in the A phase, the amplitude of the combined signal matches the amplitude reference of the A phase signal. By the way, even if the amplitude of the detection signal of the light receiving element fluctuates due to variations in the characteristics of the light emitting element of the light emitting diode and the sensitivity of the phototransistor, the detection signal in this case is close to a sine wave. The reference level of the amplitude is the light receiving element (phototransistor etc.) formed on the same chip.
In that case, even if the offset is slightly different due to dark current and may fluctuate up and down, even if the reference level obtained from the detection signal of one light receiving element is used for the reference level of the other light receiving element, In most cases, a large difference does not occur, so that even if it is used as a reference level for the detection signal of the other light receiving element, the actual phase fluctuation of the detection pulse is of little concern. Therefore,
Each detection pulse generated as a result of these comparisons holds a phase difference of 90 degrees. Here, since each of the A-phase and B-phase signals has a waveform close to a sine wave that simply increases and decreases before and after the peak, the above-described phase relation of increase and decrease is maintained even if there is some level fluctuation. Therefore, it has almost no effect on the detection pulses of the A phase and the B phase. Moreover, neither the variable resistor nor the capacitor is included in the configuration of the detection circuit of the rotary encoder. Therefore, it becomes a non-adjustment circuit suitable for IC.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram centering on a detection circuit of an embodiment to which a rotary encoder of the present invention is applied, and FIG. 2 is an explanatory diagram of a comparison operation of a comparator when the A phase leads the B phase by 90 degrees. 3, FIG. 3 is an explanatory diagram of a comparison operation of the comparator when the level of the B phase is changed, and FIG. 4 is an explanatory diagram of a subtraction voltage value generation circuit for returning the A + B phase signal to the amplitude reference of the A phase. The same components as those in FIG. 5 are designated by the same reference numerals. Therefore, their explanation is omitted.

In FIG. 1, Ra is a load resistance of the light receiving element 14 on the A phase side, which is a fixed resistance provided in place of the variable resistor R1. Rb is the light receiving element 1 on the B phase side
5 is a load resistance, which is a fixed resistance provided in place of the variable resistor R2. The outputs from these load resistors Ra and Rb are sent to the adder / subtractor circuit 1, where they are output as A + B phase signals and sent to the comparators 16 and 17.

The addition / subtraction circuit 1 is composed of a signal synthesis circuit 2, an operational amplifier 3, and a subtraction voltage value generation circuit 4. The signal synthesizing circuit 2 comprises a resistor 2a which receives the A-phase signal and is applied to the (+) input terminal of the operational amplifier 3, and a resistor 2b which receives the B-phase signal and is similarly applied to the (+) input terminal of the operational amplifier 3. The operational amplifier 3 is a non-inverted amplifier, receives the A + B phase signal synthesized by the signal synthesis circuit 2 and the voltage value to be subtracted from the subtraction voltage value generation circuit 4, and adds / subtracts these signal levels to perform an amplitude reference level. Generates an A + B phase signal approximately equal to the A phase. The resistor Rf is a feedback resistor that determines the amplification factor of the operational amplifier 3 and adjusts the output level of the A + B phase signal signal.

The comparator 16 receives the A-phase signal output from the load resistor Ra on its reference signal terminal side ((-) side),
A from the operational amplifier 3 to the input signal terminal side ((+) side)
A when the + B phase signal is received and the level of the A phase signal is exceeded
A pulse is generated corresponding to the + B phase signal, and this is used as the A phase detection output. The comparator 17 receives the A-phase signal output from the load resistor Rb on its input signal terminal side ((+) side) and the A + B-phase signal from the operational amplifier 3 on its reference signal terminal side ((-) side). A pulse is generated corresponding to the B-phase signal at the time when the level of the A + B-phase signal is exceeded, and this is used as the B-phase detection output.

Therefore, when the A-phase leads the B-phase by 90 degrees, the comparator 16 outputs the A + B-phase signal with reference to the phase of the A + B-phase signal, as shown in (a) and (b) of FIG. The detection pulse PA is generated in the phase range of 90 to 270 degrees which exceeds the level of the A phase signal. Comparator 17
Then, the detection pulse PB is generated in the phase range of 180 degrees to 360 degrees where the A + B phase signal becomes equal to or lower than the B phase level with reference to the phase of the A + B phase signal.

Even if the B-phase level fluctuates and drops, the B-phase signal lags the A-phase by 90 degrees as shown in FIG. 3 (a). Signal is A + B
A positive increase starts at the 90 ° phase point of the phase signal,
The relationship in which the negative decrease starts from the point of the phase of 270 degrees is not broken. Therefore, as shown in FIG. 3B, in the comparator 16, the detection pulse PA is generated in the phase range of 90 to 270 degrees in which the A + B phase signal exceeds the A phase level, and the rising and falling positions of this pulse are detected. Changes little. The same applies to the comparator 17, and since the A-phase signal leads the B-phase signal by 90 degrees, the negative direction begins to decrease at the 180-degree phase point of the A + B-phase signal and the 360-degree phase Since the increase in the positive direction starts from the point, the A + B phase signal becomes below the B phase level 1
The detection pulse PB is generated in the phase range of 80 degrees to 360 degrees, and the rising and falling positions of this pulse hardly change.

As shown in FIG. 4, the subtraction voltage value generation circuit 4 comprises a peak hold circuit 5 and a reference value generation circuit 6. The peak hold circuit 5 detects the maximum value of the voltage signal on the A phase side and sends it to the reference value generation circuit 6. The reference value generation circuit 6 generates a predetermined comparison reference value from the maximum voltage value by resistance division or the like and applies it to the reference signal terminal side ((-) side) of the operational amplifier 3. The peak hold circuit 5 includes a comparator 51, a gate circuit 52, an up counter 53, and a D / A conversion circuit (D / A) 54, and the gate circuit 52 is an external clock generation circuit 55.
The comparator 51 receives the clock signal from the
At the time of level, the gate is opened and the clock from the outside is sent to the up counter 53. The up counter 53 is
The clock received from the gate circuit 52 is counted and the count value is sent to the D / A conversion circuit 54. The D / A conversion circuit 54 converts it into an analog value and adds it to the reference signal terminal side ((-) side) of the comparator 51.
It is sent to the reference value generation circuit 6.

The comparator 51 receives the A phase signal on the input signal terminal side ((+) side) and compares it with the value of the D / A conversion circuit 54, and the A phase signal exceeds the value of the D / A conversion circuit 54. The HIGH level signal is continuously sent to the gate circuit 52 for as long as it is kept. As a result, the A-phase signal becomes maximum, the value is A / D converted and added to the reference signal terminal side ((-) side), and when the A-phase signal starts to decrease from the maximum next time, the comparator 51 The gate circuit 52 outputs a LOW level signal.
Send to. At this time, the gate of the gate circuit 52 is closed and the up counter 53 stops counting. As a result, the count value is held at the maximum value.

At this time, the reference value generation circuit 6 receives the voltage signal of the maximum value from the D / A conversion circuit 54, and thereafter, the state is maintained. The peak hold circuit 5 is
Upon receiving a reset signal R generated when the power is turned on or the like from the outside, the values of the up counter 53 and the like are cleared to zero, and other circuits are also reset to the initial state.

The reference value generating circuit 6 includes a buffer amplifier 61.
And a resistance voltage dividing circuit 62. Buffer amplifier 61
Is a so-called voltage follower circuit, and the resistance voltage dividing circuit is composed of resistors Rc and Rd, and obtains a subtraction value that determines the reference voltage value of the amplitude of the A + B phase signal from the maximum voltage value. The voltage division ratio in this case is 0.
It is in the range of 50 to 0.65 and is selected in advance according to the magnitude of the dark current of the light receiving element 14. Usually, considering the offset of the minimum current due to dark current, A + B
The subtraction value for calculating the reference voltage of the amplitude of the phase signal is a maximum value of about 0.6.

By the way, when the light receiving elements 14 and 15 are built in one light receiving device 7, normally,
Phototransistors of the light receiving elements 14 and 15 are formed on the same chip. Therefore, a slight difference occurs in the level of the minimum voltage of the detection signal due to the dark current depending on the characteristics of the phototransistor, and the detection sensitivity of the light emitting element 13 causes a difference in the amplitude of the detection signal. There is not much difference in the potential that serves as the reference. Therefore, if the subtraction value that matches the amplitude reference of the A + B phase signal is automatically set as the reference voltage of the reference value generation circuit 6, the maximum value of the other signal is obtained and the amplitude reference of that signal is not obtained. However, the manufacturing yield does not deteriorate. Of course, when manufacturing a rotary encoder with high accuracy, it is better to obtain the maximum value or the maximum value and the minimum value for each of the A phase and the B phase, and to obtain the voltage as the amplitude reference of each signal. There is no. When obtaining the minimum value, the counter 53 may be a down counter, a preset value may be set to decrement the value according to the clock, and the gate of the gate circuit 52 may be closed at the minimum value.

As described above, the relationship between the A-phase and the B-phase is the same even when the A-phase and the B-phase are interchanged, and even if the signal of the A-phase has some level fluctuation, the detection pulse rises, The fall timing relationship is maintained. Even if the A phase is delayed from the B phase, the same thing as the above operation can be said. Further, in the embodiment, the adder / subtractor circuit for generating the A + B phase signal is composed of the resistor, the operational amplifier and the subtraction voltage value generating circuit, but any circuit can be used as long as it is a circuit for generating the signal of the level of the A + B phase signal. Can be This circuit may generate a signal at the level of the A + B phase signal approximately. Further, in the embodiment, the two light receiving elements receive light emitted from one light emitting element, but each of the light receiving elements may be provided with a corresponding light emitting element.

[0022]

According to the present invention, by comparing the signals of the A + B phase and the signals of the respective phases in which the signals of the A phase and the B phase are added, the signals of the A phase are compared with each other. Since the signal level of the A phase is exceeded during the time from when the peak of the A side is crossed to the peak of the negative side of the A phase, a detection pulse is generated without fail. From the time point when it is lower than the peak on the positive side of B to the peak on the negative side of B phase, the level of the signal of B phase is lower, so that the detection pulse can be reliably generated, so that the result of these comparisons occurs. Each detection pulse can be held at a phase difference of 90 degrees. As a result, since it is not necessary to use a variable resistor or a capacitor as a detection circuit of the rotary encoder, it is suitable for an IC and can be an unadjusted circuit.

[Brief description of drawings]

FIG. 1 is a block diagram centering on a detection circuit of an embodiment to which a rotary encoder of the present invention is applied.

FIG. 2 is an explanatory diagram of a comparison operation of a comparator when the A phase leads the B phase by 90 degrees.

FIG. 3 is an explanatory diagram of a comparison operation of a comparator when a B-phase level changes.

FIG. 4 is an explanatory diagram of a subtraction voltage value generation circuit for returning the A + B phase signal to the amplitude reference of the A phase.

FIG. 5 is a block diagram of a main part of a detection circuit of a conventional rotary encoder.

FIG. 6 is a block diagram of a main part of another detection circuit of a conventional rotary encoder.

[Explanation of symbols]

1 ... Addition / subtraction circuit, 2 ... Signal combining circuit, 3 ... Operational amplifier,
4 ... Subtraction voltage value generation circuit, 5 ... Peak hold circuit, 6
... reference value generation circuit, 10 ... detector, 11 ... rotation axis, 12
... disk, 12a ... slit (slit portion), 13 ... light emitting diode, 14, 15 ... light receiving element (phototransistor), 16, 17 ... comparator, 51 ... comparator, 52 ... gate circuit, 53 ... up counter, 54 ...
D / A conversion circuit (D / A) 55 ... Clock generation circuit.

Claims (3)

[Claims] 1. A first and a second light receiving element for receiving light from a light emitting element through a slit formed in a rotating disk and generating detection signals of substantially sinusoidal waves having a phase difference of approximately 90 ° from each other. And an amplifier circuit that receives the outputs of the first and second light receiving elements and subtracts a predetermined reference value from the analog-added signals of these signals to output, or generates an output that approximates this. A first comparator that receives the output of the amplifier circuit at one input and receives the output of the first light receiving element at the other input to compare them; and receives the output of the amplifier circuit at one input. A second comparator that receives the output of the second light receiving element at the other input and compares them, a peak hold circuit that receives the signal from the first light receiving element and holds the peak value thereof, and this peak hold circuit A rotary encoder and a reference value generating circuit for generating the reference value from the hold value. 2. The peak hold circuit includes a comparator for comparing the current detection signal of the first light receiving element with the value of the immediately previous detection signal, and the current detection signal is set to the immediately preceding value according to the comparison result of the comparator. When the current detection signal is equal to or smaller than the immediately previous detection signal, a counter that stops counting the clock signal when the current detection signal becomes equal to or smaller than the immediately previous detection signal, and a value of this counter D / which is converted to a value and output to the comparator as the value of the immediately preceding detection signal
The rotary encoder according to claim 1, further comprising an A conversion circuit, wherein the output of the D / A conversion circuit is detected as the hold value. 3. A first and a second light receiving element for receiving light from a light emitting element through a slit formed in a rotating disk and generating detection signals of substantially sinusoidal waves having a phase difference of approximately 90 ° from each other. And an amplifier circuit that receives the outputs of the first and second light receiving elements and subtracts a predetermined reference value from the analog-added signals of these signals to output, or generates an output that approximates this. A first comparator that receives the output of the amplifier circuit at one input and receives the output of the first light receiving element at the other input to compare them; and receives the output of the amplifier circuit at one input. A second comparator that receives the output of the second light receiving element at the other input and compares them, a peak hold circuit that receives the signal from the first light receiving element and holds the peak value thereof, and this peak hold circuit First and second rotary encoders including a reference value generation circuit that generates the reference value from a hold value, and a first rotary encoder rotation mechanism in which the first rotary encoder is coupled and arranged corresponding to the X direction. A second rotary encoder rotation mechanism in which a second rotary encoder is coupled and arranged corresponding to the Y direction; and the first and second rotary encoder rotation mechanisms engaged with the first and second rotary encoder rotation mechanisms. And an input device including a ball for rotating the rotary encoder.