JP2009031261A - Optical encoder and electronic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact and optimal optical encoder for accurately detecting movement information such as relative position information and movement direction, used in a wide frequency range, and reducing the total number of output wires. <P>SOLUTION: The optical encoder has a received optical signal processing section comprising current distributors 14-16, an A/D converter, an AND circuit 17, exclusive OR circuits 18, 19, 20, an amplification circuit 21, and an add circuit 22. The received optical signal processing section converts a plurality of received optical signals A-C having different phases into output signals including a plurality of signal components S1-S3 having different phases and different signal levels relative to a predetermined threshold level. A plurality of movement information can be transmitted by the output signals through a single transmission path. The movement direction of a movable body 1 can be determined by a temporal relationship between pulse rises of the phase-A signal component S1 and the phase-C signal component S3. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical encoder that detects a position, a moving speed, a moving direction, and the like of a moving body using a light receiving element, and as an example, particularly used in a printing machine such as a copying machine or a printer, an FA (factory automation) apparatus, or the like. And a suitable optical encoder.

  Conventionally, as an optical encoder, a plurality of light receiving elements are arranged at intervals of one-fourth of the arrangement pitch of the slits in the arrangement direction of the slits of the rotating body, and the output signals of these light receiving elements are compared, thereby improving reliability. Has been proposed (Patent Document 1 (Japanese Patent Laid-Open No. 59-40258)).

  Further, the optical encoder described in Patent Document 4 (Japanese Patent Laid-Open No. 2005-61896) employs a method of increasing the accuracy of detecting the amount of movement of the moving body by generating and outputting a triangular wave.

  In Patent Document 2 (Japanese Patent Laid-Open No. 2000-121390), the A phase signal and the B phase signal having a phase difference of 90 ° are subjected to PWM conversion according to the moving direction of the scale by performing pulse conversion. It is disclosed that measurement pulse signals of A phase and B phase can be output by one transmission line by outputting them as A / B phase pulse signals of the system.

  In Patent Document 3 (Japanese Patent Laid-Open No. 60-88316), the two-phase output of the rotary encoder is signal-converted to extract counter pulses corresponding to the two phases, and one counter pulse is phase-inverted to the other. It is disclosed that a signal can be transmitted by a single output signal line by adding the counter pulse.

  By the way, in the optical encoder described in Patent Document 1, the relative position change and the moving direction of the moving body (rotating body) are detected by using two output signals of A phase and B phase whose phases are different from each other by 90 °. Yes.

  However, the optical encoder disclosed in Patent Document 1 is provided with two outputs, and wiring for two outputs is required. Thus, the output wiring of signals is not simple, and is not suitable for downsizing the mounting area. In addition, the timing of the two output signals that should be 90 ° out of phase may change due to the difference in the wiring length of the two output wirings or the noise received by each wiring. An output method is required.

  Further, in Patent Document 2, the A phase signal and the B phase signal having a phase difference of 90 ° are pulse-converted and output as one system A / B phase pulse signal PWM-modulated according to the moving direction of the scale. ing.

  However, if it is a moving body that always moves at a constant cycle, it is possible to detect the moving direction with a PWM (pulse width modulation) signal. Due to the influence on the output component as the pulse width and jitter, it becomes difficult to detect the moving direction of the moving body with high accuracy. Further, in a signal obtained by combining two-phase signal components into one, the number of movement positions counted in one cycle is equivalent to one phase, and the resolution is halved compared to the optical encoder of Patent Document 1.

  Further, in Patent Document 3, one of two-phase counter pulse signals obtained from a rotary encoder is added after being inverted in phase so that a signal can be transmitted through a single output signal line. Since the resolution is halved as in the case of Patent Document 2, relative position information cannot be obtained with high accuracy.

  Furthermore, both Patent Documents 2 and 3 aim to halve the total number of wires by signal processing, but a counter, a pulse modulator, an oscillator, and the like are required. Therefore, not only the frequency that can be used is limited, but it is necessary to synchronize with the output unit and the configuration becomes complicated, so it is difficult to reduce the size of the portion where the encoder module is mounted.

  Furthermore, in the thing of patent document 2, it applies PWM modulation by microcomputer control according to the movement information of a moving body. That is, since PWM modulation is applied depending on the processing speed of the microcomputer and the frequency of the internal oscillator, it is difficult to determine the moving direction at the moment when the moving direction of the moving body is switched.

  Similarly, in Patent Document 3, the allowable period of the moving body depends on the frequency of the oscillator. Therefore, by increasing the frequency of the oscillator, a wide range of frequencies can be handled, but the current consumption increases and is not suitable for practical use.

  Both documents aim to halve the total number of wires by signal processing. However, a counter, a pulse modulator, an oscillator, etc. are required, and it is necessary to synchronize with the output unit, resulting in a complicated configuration. Therefore, it is difficult to reduce the size of the portion where the encoder module is mounted.

Also in the optical encoder described in Patent Document 4, as in the optical encoder described in Patent Document 1, it is necessary to use a two-phase output in order to detect the moving direction.
JP 59-40258 JP 2000-121390 A JP-A-60-88316 Japanese Patent Laid-Open No. 2005-61896

  Accordingly, an object of the present invention is to detect movement information such as relative position information and movement direction with high accuracy, and can be used in a wide frequency range, and can reduce the total number of output wirings. It is to provide a formula encoder.

In order to solve the above problems, an optical encoder of the present invention includes a light emitting unit and a light receiving unit including a plurality of light receiving elements arranged in one direction in a region where light from the light emitting unit can reach. A light-on portion that causes the light to enter the light receiving element when passing through a predetermined position corresponding to the light receiving element and the light receiving light when passing through a predetermined position corresponding to the light receiving element. An optical encoder that has a light-off portion that is not incident on the element and detects the movement of the moving body in which the light-on portion and the light-off portion alternately pass the predetermined position when moving in the one direction. Yes,
A plurality of light receiving signals having different phases are input from the plurality of light receiving elements, and signal processing including at least one signal processing of logical operation processing, addition processing, and subtraction processing is performed on the plurality of light receiving signals. And a light receiving signal processing unit for outputting an output signal including a plurality of signal components having different phases and different signal levels with respect to a predetermined threshold level.

  According to the optical encoder of the present invention, the received light signal processing unit converts a plurality of received light signals having different phases into an output signal including a plurality of signal components having different phases and different signal levels with respect to a predetermined threshold level. With this output signal, a plurality of pieces of movement information can be transmitted using a single transmission line. In addition, this output signal has a plurality of output components with different phases per cycle, so that highly accurate position information can be obtained, and the encoder module can be miniaturized and the electrical wiring can be simplified without reducing the resolution. I can plan.

  Further, the configuration of the present invention does not require the configuration of the synchronization circuit by the internal oscillator, so that the moving speed of the moving body is not limited on the circuit. Therefore, according to the present invention, a stable output can be obtained in a wide frequency range.

  An optical encoder according to an embodiment includes a plurality of detection units configured by the light receiving element and the light reception signal processing unit, and the plurality of detection units can move a plurality of moving bodies that move in different directions. To detect.

  According to the optical encoder of this embodiment, even when there are two or more moving bodies, highly accurate movement information of two or more moving bodies can be obtained, and the number of output signal transmission paths can be halved. The encoder module can be downsized and the electrical wiring can be simplified. For example, when two or more moving bodies are used to detect a two-dimensional or three-dimensional moving direction, the number of output signal transmission paths can be halved from the conventional 4, 6 to 2, 3.

  In the optical encoder according to an embodiment, the light reception signal processing unit subtracts the plurality of light reception signals, and outputs an output signal including a plurality of signal components having different phases and different signal levels with respect to a predetermined threshold level. A subtracting circuit is generated.

  According to this embodiment, the light reception signal processing unit generates an output signal including a plurality of signal components having different phases and different signal levels with respect to a predetermined threshold level by subtracting the plurality of light reception signals by a subtraction circuit. Therefore, unlike the conventional example in which a single pulse is generated and output using a pulse modulator or an oscillator, it can be sufficiently integrated in the signal processing unit, and the mounting area can be reduced.

Further, in the optical encoder of one embodiment, the light reception signal processing unit is
An exclusive OR circuit that calculates the exclusive OR of the first and second signals whose phases obtained from the plurality of received light signals are 90 ° different from each other and outputs a third signal;
An AND circuit that calculates a logical product of the third signal output from the exclusive OR circuit and one of the first and second signals and outputs a fourth signal;
A subtracting circuit for subtracting a fourth signal output from the AND circuit from the other of the first and second signals and outputting a fifth signal.

  According to this embodiment, the received light signal processing unit includes the fifth signal including a plurality of signal components having different phases and different signal levels with respect to a predetermined threshold level by the exclusive OR circuit, the AND circuit, and the subtracting circuit. And the pulse widths of a plurality of signal components having different signal levels of the fifth signal are changed. Therefore, according to this embodiment, the fifth signal obtained by performing simple logical operation and subtraction on the first and second signals having phases different from each other by 90 ° obtained from the plurality of light receiving signals. Thus, the pulse width of one phase of the threshold level can be changed. Therefore, the logic value of the fifth signal can be changed depending on whether the moving direction of the moving body is normal or reverse, and detection errors in the normal or reverse direction of the moving direction can be avoided.

  In the optical encoder according to an embodiment, the light reception signal processing unit includes a comparison unit that compares a signal output from the subtraction circuit with a predetermined reference voltage and outputs the comparison result.

  According to this embodiment, the comparison unit included in the received light signal processing unit outputs a result of comparing the output signal of the subtraction circuit that may vary under various optical conditions and the predetermined reference voltage, so that the threshold level Therefore, it is possible to avoid the possibility of malfunction by avoiding complicated signal processing in the subsequent stage due to fluctuations in the output signal of the subtraction circuit.

  Further, the threshold level of the output of the comparison unit can be arbitrarily changed by the reference voltage. As a result, it is possible to extract only an arbitrary output component from the output of the comparison unit, and when high accuracy is not required, one phase of the plurality of phase information included in the output signal of the subtraction circuit It is also possible to obtain only the information.

  In the optical encoder according to an embodiment, the received light signal processing unit receives the fifth signal output from the subtracting circuit as an input to the inverting input terminal and inputs a predetermined reference voltage to the non-inverting input terminal. A negative feedback circuit including an operational amplifier;

  According to this embodiment, the negative feedback circuit can stabilize the threshold level of the fifth signal from the subtraction circuit, and the amplitude of the output signal of the negative feedback circuit can be adjusted by adjusting the gain in the negative feedback circuit. Can be easily adjusted to the threshold level.

  In one embodiment, the received light signal processing unit includes a reference voltage unit that can change the value of the predetermined reference voltage.

  According to the optical encoder of this embodiment, the reference voltage unit included in the light reception signal processing unit changes the value of the predetermined reference voltage, so that the comparison unit does not increase the output wiring from the light reception signal processing unit. It is possible to extract only an arbitrary output component from the outputs.

  In the optical encoder according to an embodiment, the light reception signal processing unit includes an analog signal generation circuit that generates an analog signal, and an output signal including an analog signal component generated by the analog signal generated by the analog signal generation circuit. Is output.

  According to the optical encoder of this embodiment, it is possible to increase the accuracy of detection of the moving amount of the moving body according to the resolution of the analog signal component included in the output signal output from the light receiving signal processing unit. In addition, it is possible to detect the moving direction of the moving body based on the waveform fluctuation due to the analog signal component.

  As the analog signal generation circuit, for example, a circuit in which a capacitor is added to an amplifier unit, a logic output circuit unit, or the like that amplifies a received light signal can be employed so as to give a time width to the rise and fall of the signal. As the analog signal generation circuit, for example, a circuit that reduces the gain of an amplifier that amplifies the received light signal and gives a time width to the rise and fall of the signal can be employed. Both circuits are circuits that can be configured very easily. The analog signal is not limited to that obtained from the light reception signal, and a clock for generating a triangular wave, for example, may be used as the analog signal.

  In the optical encoder according to an embodiment, the light reception signal processing unit includes a digital signal generation circuit that generates a digital signal having a phase different from that of the analog signal generated by the analog signal generation circuit from the light reception signal. A subtracting circuit for subtracting the analog signal and the digital signal to generate an output signal including a plurality of signal components having different phases and different signal levels with respect to a predetermined threshold level;

  According to the optical encoder of this embodiment, since the output signal is generated by the subtracting circuit provided in the light receiving signal processing unit, it is possible to avoid a change in time constant due to the gain change of the amplifier unit and the addition of the capacitance. Furthermore, since an additional circuit such as an oscillator is not required, it is possible to detect the moving amount and moving direction of the moving body with high accuracy without giving frequency dependency.

  An electronic apparatus according to an embodiment includes the optical encoder, the output signal including a plurality of signal components having different phases output from the received light signal processing unit and different signal levels with respect to a predetermined threshold level, and A comparison unit that compares the reference voltage corresponding to the threshold level and outputs the comparison result is provided.

  According to the electronic apparatus of this embodiment, the comparison unit can output a signal converted into a digital value by comparing the output signal from the optical encoder with a reference voltage corresponding to the threshold level. That is, even when the output signal from the optical encoder is an analog output signal and cannot be directly processed by a microcomputer or the like, the output signal can be converted into a digital signal by the comparator. Therefore, the movement information of the moving body can be obtained by inputting the digitized output signal from the comparison unit to the microcomputer included in the electronic apparatus. For example, by adopting the electronic apparatus of this embodiment in the ink head portion of an ink jet printer, movement information of the ink head portion as a moving body can be easily obtained while reducing the number of wires output from the optical encoder. .

  The electronic apparatus according to an embodiment compares an output signal including the analog signal component output from the light reception signal processing unit of the optical encoder with a plurality of different reference voltages, and a plurality of digital signals based on the comparison result. A comparator for outputting a signal;

  According to the optical encoder of this embodiment, highly accurate movement information of the moving body can be obtained by the plurality of digital signals output from the comparison unit. Moreover, since the comparison unit outputs a digital signal, it can be directly processed by a microcomputer or the like.

  Moreover, an electronic apparatus according to an embodiment includes the optical encoder. According to this electronic apparatus, the number of wires for the optical encoder can be reduced, the size can be reduced, and movement information can be detected with high accuracy.

  According to the optical encoder of the present invention, the received light signal processing unit converts a plurality of received light signals having different phases into an output signal including a plurality of signal components having different phases and different signal levels with respect to a predetermined threshold level. With this output signal, a plurality of pieces of movement information can be transmitted using a single transmission line. Further, since this output signal has a plurality of output components having different phases per cycle, highly accurate position information can be obtained, and the encoder module can be miniaturized and the electrical wiring can be simplified.

  Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

(First embodiment)
FIG. 1 shows a first embodiment of an optical encoder according to the present invention. The first embodiment includes a moving body 1, a light receiving unit 2, and a light emitting unit 3. The light emitting unit 3 is composed of a light emitting element such as an LED (light emitting diode). The light receiving unit 2 includes three light receiving elements 11 to 13. Further, the moving body 1 is movable in the direction indicated by the arrow X1 or X2, and the light-on part 6 and the light-off part 7 are arranged alternately in the movement direction. When the arrangement pitch of the light-on parts 6 is P, the dimension (width dimension) in the moving direction of the light-on part 6 and the light-off part 7 is (1/2) P. The light-on unit 6 allows light from the light-emitting unit 3 to pass to the light-receiving unit 2 side, while the light-off unit 7 does not allow light from the light-emitting unit 3 to pass to the light-receiving unit 2 side. In this embodiment, the light receiving elements 11 to 13 are configured with photodiodes, but may be configured with phototransistors. In this embodiment, the width dimension of each of the light receiving elements 11 to 13 is (1/12) P. In addition, the light receiving elements 11 to 13 are adjacent to each other in the moving direction without being spaced apart.

  Therefore, the received light signals A, B, and C output from the light receiving elements 11, 12, and 13 are shifted in phase by 30 ° when one pitch P is 360 ° as shown in FIG. The light receiving signals A, B, C output from the respective light receiving elements 11, 12, 13 are input to the AND circuit 17 via the current distributors 14, 15, 16 and AD converters (not shown). , AND operation is performed. The logical product circuit 17 outputs the logical product signals A, B, and C having the waveforms shown in FIG. 2 to the three exclusive OR circuits 18 to 20.

  The exclusive logical sum circuit 18 receives the logical product signals A, B, and C and the light reception signal A that has passed through the current distributor 14 and the AD converter. The exclusive logical sum circuit 18 receives both signals. And the signal A ′ after the calculation is output to the adder circuit 22. The exclusive OR circuit 19 receives the logical product signals A, B, and C, and the light reception signal B that has passed through the current distributor 15 and the AD converter. The exclusive OR circuit 19 The exclusive OR of both signals is calculated, and the calculated signal B ′ is output to the adder circuit 22. The exclusive OR circuit 20 receives the logical product signals A, B, and C, and the light reception signal C that has passed through the current distributor 16 and the AD converter. The exclusive OR of both signals is calculated, and the calculated signal C ′ is output to the amplifier circuit 21. The adder circuit 22 adds the calculated signals A ′ and B ′ and the signal 2 C ′ amplified twice by the amplifier circuit 21, and outputs an output signal having the waveform shown in FIG. 2.

  The current distributors 14 to 16, the AD converter, the logical product circuit 17, the exclusive OR circuits 18, 19, 20, the amplifier circuit 21, and the adder circuit 22 constitute a received light signal processing unit.

  In the output signal, as shown in FIG. 2, the pulse S1 rising between the threshold level 0 and the threshold level 1 becomes an A-phase signal component, and the pulse S2 rising between the threshold level 1 and the threshold level 2 The pulse S3 that has risen beyond the threshold level 2 becomes the B-phase signal component. Therefore, in the signal processing unit at the subsequent stage, for example, the relative movement information of the moving body 1 can be obtained by counting the rising components for the respective threshold levels 0 to 2. Further, forward / reverse (X1, X2) of the moving direction of the moving body 1 can be determined based on the leading and trailing relations of the pulse rising of the A-phase signal component and the C-phase signal component. Therefore, according to this embodiment, without losing the movement information component, the output signal output from the adder circuit 22 to the single transmission line is added with the three-phase signal components of A to C phases having different signal levels and phases. Can be put on. Therefore, according to this embodiment, it is possible to obtain highly accurate movement information while reducing the size and simplifying the electrical wiring.

  In the above embodiment, the light receiving unit 2 and the light receiving signal processing unit are provided with one detection unit. However, the detection unit includes a plurality of detection units, and the plurality of detection units move in different directions. The movement of the moving body may be detected. High-accuracy movement information of two or more moving bodies can be obtained, the number of output signal transmission paths can be halved, the encoder module can be downsized, and electrical wiring can be simplified. For example, when two or more moving bodies are used to detect a two-dimensional or three-dimensional moving direction, the number of output signal transmission paths can be halved from the conventional 4, 6 to 2, 3. The two two-dimensional movement directions may be, for example, the X direction and the Y direction inclined by 90 ° with respect to the X direction, but the inclination angle is not limited to 90 °. Thus, the moving directions may be different. Needless to say, the X direction, the Y direction, and the Z direction as the three-dimensional movement directions are not limited to a right angle as in a rectangular coordinate system.

(Second embodiment)
Next, FIG. 3A shows a second embodiment of the optical encoder of the present invention. The second embodiment includes a moving body 31, a light receiving unit 32, and a light emitting unit 33. The light emitting unit 33 is composed of a light emitting element such as an LED (light emitting diode).

  The light receiving unit 32 includes four light receiving elements 41 to 44. Further, the moving body 31 is movable in the direction indicated by the arrow X1 or X2, and the light-on part 36 and the light-off part 37 are alternately arranged in the movement direction. When the arrangement pitch of the light-on parts 36 is P, the dimension (width dimension) in the moving direction of the light-on part 36 and the light-off part 37 is (1/4) P. The light-on part 36 allows light from the light-emitting part 33 to pass to the light-receiving part 32 side, while the light-off part 37 does not allow light from the light-emitting part 33 to pass to the light-receiving part 32 side. The light receiving elements 41 to 44 are formed of photodiodes. In this embodiment, the width dimension of each of the light receiving elements 41 to 44 is (1/4) P. In addition, the light receiving elements 41 to 44 are adjacent to each other in the moving direction without being spaced apart.

  The light receiving signal A + output from the light receiving element 41 is input to the non-inverting input terminal of the differential amplifier 51 via the current / voltage converting unit 45, and the light receiving signal A− output from the light receiving element 43 passes through the current / voltage converting unit 46. Via the inverting input terminal of the differential amplifier 51. On the other hand, the light receiving signal B− output from the light receiving element 42 is input to the inverting input terminal of the differential amplifier 52 via the current / voltage converting section 48, and the light receiving signal B + output from the light receiving element 44 is the current / voltage converting section 48. To the inverting input terminal of the differential amplifier 52.

  The differential amplifier 51 amplifies the difference between the received light signal A + converted into a voltage and the received light signal A− converted into a voltage, and outputs the amplified signal to the AD converter 53. The differential amplifier 52 amplifies the difference between the light reception signal B + converted into a voltage and the light reception signal B− converted into a voltage, and outputs the amplified signal to the AD converter 54.

  The AD converter 53 converts the amplified signal input from the differential amplifier 51 into a digital signal A and outputs the digital signal A to the subtracting circuit 55. The AD converter 54 converts the amplified signal input from the differential amplifier 52 into a digital signal. The signal is converted to signal B and output to the subtracting circuit 55. Then, the subtraction circuit 55 subtracts the digital signal B from the digital signal A and outputs a subtraction signal (AB).

  In the second embodiment, the current-voltage conversion units 45 to 48, the differential amplifiers 51 and 52, the AD converters 53 and 54, and the subtraction circuit 55 constitute a light reception signal processing unit.

  In the column of (A phase preceding) in FIG. 4, when the moving body 31 moves in the direction of the arrow X1, the digital signals A and B output from the AD converters 53 and 54 and the subtraction output from the subtraction circuit 55 are displayed. The signal waveform of a signal (AB) is shown. Further, in the (B phase preceding) column of FIG. 4, when the moving body 31 moves in the direction of the arrow X2, the digital signals A and B output from the AD converters 53 and 54 and the subtraction circuit 55 output The signal waveform of the subtraction signal (AB) to be performed is shown.

  As shown in FIG. 4, according to this embodiment, by subtracting the digital signal B from the digital signal A by the subtracting circuit 55, the A phase component As, which has a different phase and a different signal level with respect to the predetermined threshold level SL. A subtraction signal (AB) including the B-phase component Bs is generated as an output signal.

  According to this embodiment, as shown in the column (A phase preceding) in FIG. 4, the upper A phase component As with respect to the threshold level SL is lower than the lower B phase component Bs with respect to the threshold level SL. Can also be determined that the moving body 31 is moving in the direction of the arrow X1. In addition, as shown in the column (B phase preceding) in FIG. 4, when the B phase component Bs precedes the A phase component As, the mobile body 31 is moving in the direction of the arrow X2. Can be determined.

  In addition, according to this embodiment, unlike the conventional example in which a single pulse is generated and output using a pulse modulator or an oscillator, only a subtracting circuit 55 that can be sufficiently integrated in the signal processing unit is added. A subtraction signal (AB) having a plurality of output components As and Bs having different phases per period can be obtained, and highly accurate position information can be obtained, whereby electrical wiring can be simplified and the mounting area can be reduced.

  FIG. 3B shows a modification of the second embodiment. In this modification, a comparison unit 66 is connected to the output side of the subtraction circuit 55. The comparison unit 66 is connected to the operational amplifier 64, the feedback resistor 63 connected between the output side of the operational amplifier 64 and the inverting input terminal of the operational amplifier 64, and the non-inverting input terminal of the operational amplifier 64. A reference voltage unit 65 is included. In this modification, as shown in FIG. 3B, the subtraction signal (A−B) output from the subtraction circuit 55 is input to the comparison unit 66. The subtraction signal (A-B) is input to the inverting input terminal of the operational amplifier 64 included in the comparison unit 66, and the reference voltage from the reference voltage unit 65 is input to the non-inverting input terminal of the operational amplifier 64. According to the output signal of the operational amplifier 64, a stable threshold level can be obtained. Further, by changing the value of the reference voltage generated by the reference voltage unit 65, it is possible to extract and output a desired signal component from the subtraction signal (AB). For example, when information regarding the moving direction is not required or when high accuracy is not required for the moving information, the reference voltage is set to the power supply voltage or the ground (GND), so that only one phase of the A phase and the B phase can be obtained. Travel information can be obtained.

  In this modification, since the output of the operational amplifier 64 is fed back to the inverting input terminal by a negative feedback circuit using the feedback resistor 63, the desired output amplitude can be set by changing the resistance value of the feedback resistor 63. Obtainable. Further, it is also possible to compress the amplitude fluctuation of the output signal by connecting a diode between the output of the operational amplifier 64 and the inverting input terminal instead of the feedback resistor 63.

  Further, in this embodiment, as shown in FIG. 7, the collector of the npn transistor 71 is connected to the reference voltage unit 65, the base is connected to the connection point of the resistor 72 and the resistor 73, and the voltage of the power supply connected to the resistor 72 The reference voltage input to the non-inverting input terminal of the operational amplifier 64 may be changed by setting Vcc to a certain fixed value or more. As a result, the reference voltage is changed in the received light signal processing unit by adjusting the power supply voltage without increasing the output wiring from the received light signal processing unit, and a desired signal component is extracted from the subtracted signal (AB). Can be output. Thus, external signal processing can be simplified when a plurality of output components are output through a single transmission line.

(Third embodiment)
Next, FIG. 5 shows a third embodiment of the optical encoder of the present invention. In the third embodiment, the exclusive OR circuit 61 and the AND circuit 62 are connected between the AD converters 53 and 54 of the second embodiment and the subtraction circuit 55, and the output of the subtraction circuit 55. This is different from the second embodiment described above in that the comparison unit 66 is connected to the side. Therefore, the third embodiment is the same as the second embodiment described above in that it includes the moving body 31, the light receiving unit 32, the light emitting unit 33, and the current-voltage conversion units 45 to 48 shown in FIG. Therefore, in the third embodiment, the same reference numerals are given to the same parts as those in the second embodiment, and the parts different from those in the second embodiment will be mainly described.

  As shown in FIG. 5, in the third embodiment, the output line 67 of the AD converter 53 and the output line 68 of the AD converter 54 are connected to the input side of the exclusive OR circuit 61. Further, the output line 68 of the AD converter 54 and the output line 69 of the exclusive OR circuit 61 are connected to the input side of the AND circuit 62. Further, the output line 70 of the AND circuit 62 and the output line 67 of the AD converter 53 are connected to the input side of the subtraction circuit 55.

  The output of the subtraction circuit 55 is connected to the comparison unit 66. The comparison unit 66 is connected to the operational amplifier 64, the feedback resistor 63 connected between the output side of the operational amplifier 64 and the inverting input terminal of the operational amplifier 64, and the non-inverting input terminal of the operational amplifier 64. A reference voltage unit 65 is included.

  In the third embodiment, the digital signals A and B as the first and second signals, which are output from the AD converters 53 and 54 and whose phases are different from each other by 90 °, are input to the exclusive OR circuit 61. The logical OR circuit 61 outputs the third signal I obtained by calculating the exclusive OR of the digital signals A and B to the output line 69.

  The logical product circuit 62 calculates the logical product of the digital signal B input from the AD converter 54 and the third signal I input from the exclusive OR circuit 61 and outputs the fourth signal J to the output line 70. Output. Then, the subtraction circuit 55 subtracts the fourth signal J from the digital signal A input from the AD converter 53 and outputs a fifth signal K.

  Here, in FIG. 6A, the digital signals A and B, the third signal I, the fourth signal as the first and second signals when the moving body 31 shown in FIG. 3 moves in the direction of the arrow X1. The signal waveforms of the signal J and the fifth signal K are shown. 6B shows the digital signals A and B, the third signal I, and the fourth signal as the first and second signals when the moving body 31 shown in FIG. 3 moves in the direction of the arrow X2. J shows the signal waveform of the fifth signal K.

  In the signal waveform of the fifth signal K shown in FIGS. 6A and 6B, the signal component As above the threshold level SL corresponds to the digital signal A, and the signal component Bs below the threshold level SL is the digital signal B. It corresponds to. Therefore, according to this embodiment, the relative position change information can be obtained by independently counting the rising edge of the pulse of the signal component As and the rising edge of the signal component Bs. The fifth signal K can be transmitted using the transmission path.

  The moving direction of the moving body 31 can be detected by detecting the temporal relationship between the pulse waveforms of the signal component As and the signal component Bs in the fifth signal K. For example, when the moving body 31 moves in the direction of the arrow X1, as shown in FIG. 6A, when the pulse waveform of the signal component As falls, the pulse waveform of the signal component Bs is generated immediately. On the other hand, when the moving body 31 moves in the direction of the arrow X2, as shown in FIG. 6B, a quarter cycle of the fifth signal K has elapsed since the pulse waveform of the signal component As has fallen. A pulse waveform of the signal component Bs is generated.

  Therefore, the moving direction of the moving body 31 can be easily detected by detecting the time difference between the signal component As and the signal component Bs in the fifth signal K output from the subtracting circuit 55. 6A and 6B, when the signal component As is sampled every quarter period (25% of the duty) of the signal K in the A column below the waveform of the fifth signal K, the threshold level SL is reached. On the other hand, logic results “1” and “0” indicating whether or not H (H level) is indicated. 6A and 6B, when the signal component Bs is sampled every quarter cycle (25% of the duty) of the signal K in the B column below the waveform of the fifth signal K, the threshold level is obtained. Logic results “1” and “0” indicating whether or not SL is at L (L level).

  In FIG. 6A, the logic result of the portion surrounded by the alternate long and short dash line BR is different from the logic result of the portion surrounded by the alternate long and short dash line BR in FIG. 6B. It can be determined whether the moving direction of the moving body 31 is the direction of the arrow X1 or the direction of the arrow X2. As an example, if the signal waveform of the fifth signal K is displayed on a waveform display device such as an oscilloscope, the moving direction can be detected from the difference in the signal waveform, so the moving direction of the moving body can be detected at any moment. . According to this embodiment, according to the fifth signal K output from the subtraction circuit 55, the logical value can be changed by the forward / reverse of the moving direction of the moving body 31, and the forward / reverse of the moving direction can be accurately detected.

  In this embodiment, as shown in FIG. 5, the fifth signal K of the subtraction circuit 55 is input to the comparison unit 66. The fifth signal K is input to the inverting input terminal of the operational amplifier 64 included in the comparison unit 66, and the reference voltage from the reference voltage unit 65 is input to the non-inverting input terminal of the operational amplifier 64. According to the output signal of the operational amplifier 64, a stable threshold level can be obtained. Further, by changing the value of the reference voltage generated by the reference voltage unit 65, it is possible to extract a desired signal component from the fifth signal K and output it. For example, when information regarding the moving direction is not required or when high accuracy is not required for the moving information, the reference voltage is set to the power supply voltage or the ground (GND), so that only one phase of the A phase and the B phase can be obtained. Travel information can be obtained.

  In this embodiment, since the output of the operational amplifier 64 is fed back to the inverting input terminal by a negative feedback circuit using the feedback resistor 63, a desired output amplitude can be obtained by changing the resistance value of the feedback resistor 63. Obtainable. Further, it is also possible to compress the amplitude fluctuation of the output signal by connecting a diode between the output of the operational amplifier 64 and the inverting input terminal instead of the feedback resistor 63.

  Further, in this embodiment, as shown in FIG. 7, the collector of the npn transistor 71 is connected to the reference voltage unit 65, the base is connected to the connection point of the resistor 72 and the resistor 73, and the voltage of the power supply connected to the resistor 72 The reference voltage input to the non-inverting input terminal of the operational amplifier 64 may be changed by setting Vcc to a certain fixed value or more. As a result, the reference voltage is changed in the received light signal processing unit by adjusting the power supply voltage without increasing the output wiring from the received light signal processing unit, and a desired signal component is extracted from the fifth signal K and output. It becomes possible. Thus, external signal processing can be simplified when a plurality of output components are output through a single transmission line.

(Fourth embodiment)
FIG. 8 shows an essential part of a fourth embodiment of the optical encoder of the present invention. In the fourth embodiment, a low-pass filter 81 composed of a resistor 82 and a capacitor 83 is connected between the AD converter 53 and the subtracting circuit 55 of the second embodiment shown in FIG. 3A. Different from form.

  In the fourth embodiment, the low-pass filter 81 serving as an analog signal generation circuit delays the rise and fall of the rectangular wave shown in FIG. 4 of the digital signal A output from the AD converter 53 in terms of time. It can be a waveform. Accordingly, in the column (A phase preceding) in FIG. 4 representing the case where the moving body 31 in FIG. 3A moves in the direction of the arrow X1, the rise of the A phase component and the B phase component of the subtraction signal (AB) are shown. The rise is gentle according to the time constant determined by the resistor 82 and the capacitor 83 of the low-pass filter 81.

  On the other hand, in the column (B phase preceding) in FIG. 4 showing the case where the moving body 31 in FIG. 3A moves in the direction of the arrow X2, the fall of the A phase component and the B phase component of the subtraction signal (AB) are shown. The falling edge becomes gentle according to the time constant determined by the resistor 82 and the capacitor 83 of the low-pass filter 81.

  Therefore, according to this embodiment, when the rising waveform of the A-phase component As of the subtraction signal (AB) is gentle as shown in the column (A-phase preceding) in FIG. It can be determined that the movement is in the direction of the arrow X1. On the other hand, when the falling waveform of the A phase component As of the subtraction signal (AB) is gentle as shown in the column (B phase preceding) in FIG. 4, the moving body 31 moves in the direction of the arrow X1. Can be determined.

  Therefore, according to the fourth embodiment, the moving direction of the moving body 31 can be changed by a very simple circuit change in which the low-pass filter 81 is connected between the AD converter 53 and the subtracting circuit 55 of the second embodiment. It can be easily discriminated.

  Instead of connecting the low-pass filter 81 between the AD converter 53 and the subtracting circuit 55, a low-pass filter is connected between the AD converter 54 and the subtracting circuit 55 to convert the digital signal B into an analog waveform. Also good. In short, a signal to be analogized may be selected so that the case of phase A preceding and the case of phase B can be distinguished. That is, the analog signal for analogization is not limited to that obtained from the light reception signal, and for example, a clock for generating a triangular wave may be used as the analog signal.

(Fifth embodiment)
Next, FIGS. 9A and 9B show a fifth embodiment of the optical encoder of the present invention. The fifth embodiment is different from the third embodiment in the following points (1), (2), and (3).

  (1) As shown in FIG. 9B, a subtracting circuit 90 is provided in place of the subtracting circuit 55 and the comparing unit 66 of FIG.

  (2) As shown in FIG. 9A, current distributors 91, 92, 93, and 94 are connected to four light receiving elements 41, 42, 43, and 44, respectively. The light reception signals A +, A−, B +, and B− are input to the current-voltage conversion units 45, 46, 47, and 48 in FIG. 9B.

  (3) As shown in FIG. 9A, a current-voltage converter 95 connected to the current distributors 91 and 92, a current-voltage converter 96 connected to the current distributors 93 and 94, and the current-voltage converter 95 9 and 96, and a comparator 98 to which the output signal of the subtraction circuit 97 is input. The output side of the comparator 98 is connected to the input side of the subtraction circuit 90 of FIG. 9B. The point that has been.

  In the fifth embodiment, the current-voltage conversion unit 95 in FIG. 9A converts a signal ((A +) + (B−)) obtained by adding the light reception signals A + and B− into a voltage signal and inputs the voltage signal to the subtraction circuit 97. To do. In this addition signal ((A +) + (B−)), the movement of the moving body 31 by one pitch P corresponds to one cycle. The current-voltage converter 96 converts a signal ((A −) + (B +)) obtained by adding the light reception signals A− and B + into a voltage signal and inputs the voltage signal to the subtracting circuit 97. The addition signal ((A −) + (B +) corresponds to one cycle of movement of the moving body 31 by one pitch P. The addition signal ((A +) + (B−)) and the addition signal ((A The phase is 180 ° different from that of (−) + (B +).

  The subtraction circuit 97 subtracts the signal ((A −) + (B +)) from the signal ((A +) + (B−)), and inputs the subtracted signal to the comparator 98. The comparator 98 compares the subtraction signal with a constant voltage VA from the DC power source 99 and outputs an analog output signal A1out. The analog output signal A1out has an analog waveform with a half-cycle triangular wave as shown in FIG. 10 regardless of the moving direction of the moving body 31. The triangular wave analog output signal A1out corresponds to one pitch of the moving body 31 in one cycle.

  The logical product circuit 62 in FIG. 9B calculates the logical product of the digital signal B input from the AD converter 54 and the third signal I input from the exclusive OR circuit 61, as in the third embodiment. The fourth signal J is output to the output line 70 by calculation. In the fourth signal J, one period corresponds to one pitch movement of the moving body 31 as shown in FIG.

  The fourth signal J and the analog output signal A1out output from the subtraction circuit 97 are input to the subtraction circuit 90. The subtraction circuit 90 subtracts the fourth signal J from the analog output signal A1out. The analog output signal A2out is output.

  The (A phase preceding) column in FIG. 10 shows signal waveforms of the analog output signal A1out, the fourth signal J, and the analog output signal A2out when the moving body 31 moves in the direction of the arrow X1. In this case, the signal waveform of the analog output signal A2out is a waveform in which a rectangular wave for a quarter period is output downward simultaneously with the fall of the analog output signal A1out. On the other hand, when the moving body 31 moves in the direction of the arrow X2, the signal waveform of the analog output signal A2out is 4 minutes from the trailing edge of the analog output signal A1out, as shown in the column (B phase preceding) in FIG. Is a waveform in which a rectangular wave is output to the lower side with a delay of 1 cycle.

  Therefore, according to the fifth embodiment, in the case of preceding the A phase, the rectangular wave component of the analog output signal A2out output from the comparator 98 appears immediately after the triangular wave component of the analog output signal A1out. On the other hand, in the case of phase B preceding, the rectangular wave component of the analog output signal A2out output from the comparator 98 appears with a quarter cycle delay from the triangular wave component of the analog output signal A1out. Due to the difference in waveform, the moving direction of the moving body 31 can be easily detected. Further, according to the fifth embodiment, the movement amount can be detected with high accuracy by the triangular wave portion of the analog output signal A2out. Further, according to the fifth embodiment, since it is not necessary to change the gain of the amplifier or the time constant, it is possible to operate stably in a wide frequency range.

  In the above embodiment, the output signal J, which is the logical product of the exclusive OR of the digital signals A and B and the digital signal B, is used as the digital signal, but the exclusive of the digital signals A and B is used as the digital signal. A logical product signal of the logical OR and the digital signal A may be used. In short, a digital signal that can discriminate between the case of phase A preceding and the case of phase B preceding may be used.

(Sixth embodiment)
Next, FIG. 11 shows a sixth embodiment which is an electronic apparatus provided with the optical encoder of the first embodiment of the present invention. The sixth embodiment is provided with first, second, and third comparators 101, 102, and 103 connected to the output side of the adder circuit 22 of the first embodiment shown in FIG. Different from form. Therefore, in the sixth embodiment, differences from the above-described first embodiment will be mainly described.

  As shown in FIG. 11, the sixth embodiment includes first to third three comparators 101 to 103 as comparison units, and the non-inverting input terminal of the three comparators 101 to 103 is an adder circuit 22. It is connected to the output side. The inverting input terminal of the first comparator 101 is connected to a DC power source 105 that generates the first reference voltage V0. The inverting input terminal of the second comparator 102 is connected to a DC power source 106 that generates the second reference voltage V1. The inverting input terminal of the third comparator 107 is connected to the DC power source 107 that generates the third reference voltage V2. The first, second, and third reference voltages V0, V1, and V2 correspond to the threshold levels 0, 1, and 2 shown in FIGS. 2, 12A, and 12B, respectively.

  12A shows the waveforms of the received light signals A, B, and C, the waveform of the output signal Y of the adder circuit 22, and the first, second, and third comparators 101 when the moving body 1 in FIG. 1 moves to the arrow X1. , 102, 103 are waveform diagrams showing waveforms of output signals XA, XB, XC. 12B shows the waveforms of the received light signals A, B, and C, the waveform of the output signal Y of the adder circuit 22, and the first, second, and third waveforms when the moving body 1 in FIG. It is a wave form diagram which shows the waveform of the output signals XA, XB, XC of the comparators 101, 102, 103.

  As shown in FIGS. 12A and 12B, the waveform of the output signal XA of the first comparator 101 is a waveform in which the logic is switched by the rising and falling of the received light signals A and C. Since the moving amount of the moving body 1 can be detected only by the output signal XA, a configuration including only the first comparator 101 among the first to third comparators 101 to 103 is possible. A configuration including only one of the first to third comparators 101 to 103 is also possible.

  On the other hand, the moving direction of the moving body 1 cannot be detected only by the output signal XA. Therefore, the moving direction of the moving body 1 can be detected by detecting the difference in logic switching between the output signal XA and the output signal XC. For example, the exclusive OR circuit takes an exclusive OR of the output signal XA and the output signal XC, and a signal Z based on this exclusive OR is input as a counter clock. Depending on the preceding and following relationship of the signal Z based on this exclusive OR, signals with different pulse widths can be output, and the forward and backward (X1, X2) of the moving direction of the moving body 1 can be discriminated by the length of the pulse width of this signal. Become.

  Further, instead of taking the exclusive OR of the output signal XA and the output signal XC, the exclusive OR circuit takes the exclusive OR of the output signal XA and the output signal XB, and the signal Z2 by this exclusive OR is obtained. May be input as the clock of the counter. Signals having different pulse widths may be output depending on the preceding and following relationship of the signal Z2 based on this exclusive OR. In short, as shown in FIGS. 12A and 12B, the moving direction of the moving body 1 can be detected by using the fact that the output signal XB and the output signal XC have different waveforms depending on the moving direction of the moving body 1. Therefore, a method other than those described above can be appropriately selected as a signal processing method for that purpose. The signal processing may be performed by a simple method using a microcomputer.

  Therefore, according to the electronic apparatus of the sixth embodiment, the first, second, and third reference voltages V0, V1, and V2 that compare the output signal of the adder circuit 22 with the first, second, and third reference voltages V0, V1, and V2. By connecting the comparators 101, 102, and 103 to the external signal processing unit having the logical product circuit 110, the exclusive logical sum circuit, or the counter, the amount of movement of the moving body 1 can be reduced while the number of output wires is reduced. Movement information including the movement direction can be easily obtained.

  According to the electronic apparatus provided with the optical encoder of the first to fifth embodiments, the number of wires for the optical encoder can be reduced, the size can be reduced, and the movement information can be detected with high accuracy. . For example, by adopting the electronic device of the sixth embodiment as an ink head part of an ink jet printer, movement information of the ink head part as a moving body can be easily obtained while reducing the number of wires output from the optical encoder. can get.

1 is a diagram schematically illustrating a first embodiment of an optical encoder according to the present invention. It is a wave form diagram which shows each signal waveform in the light reception signal processing part of the said 1st Embodiment. It is a figure which shows typically 2nd Embodiment of the optical encoder of this invention. It is a figure which shows the modification of the said 2nd Embodiment typically. It is a wave form diagram which shows each signal waveform in the light reception signal processing part of the said 2nd Embodiment. It is a figure which shows typically 3rd Embodiment of the optical encoder of this invention. It is a wave form diagram which shows each signal waveform in the light reception signal processing part of the said 3rd Embodiment. It is a wave form diagram which shows each signal waveform in the light reception signal processing part of the said 3rd Embodiment. It is a circuit diagram which shows the modification of the reference voltage part of the said 3rd Embodiment. It is a circuit diagram which shows the principal part of the optical encoder of 4th Embodiment of this invention. It is a figure which shows typically a part of optical encoder of 5th Embodiment of this invention. It is a circuit diagram which shows a part of light reception signal process part of the optical encoder of the said 5th Embodiment. It is a wave form diagram which shows the signal waveform in the light reception signal process part of the said 5th Embodiment. It is a figure which shows a part of received light signal processing part of the electronic device of 6th Embodiment of this invention. It is a wave form diagram which shows each signal waveform in the light reception signal processing part of the said 6th Embodiment. It is a wave form diagram which shows each signal waveform in the light reception signal processing part of the said 6th Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 31 Mobile body 2, 32 Light-receiving part 3, 33 Light-emitting part 6, 36 Light-on part 7, 37 Light-off part 11-13, 41-44, Light-receiving element 14-16 Current divider 17, 62 AND circuit 18 -20, 61 Exclusive OR circuit 21 Amplifier circuit 22 Adder circuit 45-48 Current-voltage conversion unit 51, 52 Differential amplifier 53, 54 AD converter 55 Subtraction circuit 63 Feedback resistor 64 Operational amplifier 65 Reference voltage unit 66 Comparison unit 81 Low-pass filter 82 Resistance 83 Capacitor 90, 97 Subtraction circuit 91-94 Current distribution unit 95, 96 Current-voltage conversion unit 101-103 Comparator

Claims (12)

A light-receiving unit, and a light-receiving unit having a plurality of light-receiving elements arranged in one direction in a region where light from the light-emitting unit can reach, and when passing a predetermined position corresponding to the light-receiving element A light-on portion that causes the light to enter the light-receiving element; and a light-off portion that prevents the light from entering the light-receiving element when passing through a predetermined position corresponding to the light-receiving element. An optical encoder that detects the movement of the moving body in which the light-on part and the light-off part alternately pass through the predetermined position when moving in a direction;
A plurality of light receiving signals having different phases are input from the plurality of light receiving elements, and signal processing including at least one signal processing of logical operation processing, addition processing, and subtraction processing is performed on the plurality of light receiving signals. An optical encoder comprising: a received light signal processing unit that outputs an output signal including a plurality of signal components having different phases and different signal levels with respect to a predetermined threshold level. The optical encoder according to claim 1,
An optical encoder, comprising: a plurality of detection units constituted by the light receiving unit and the light reception signal processing unit, wherein the movements of a plurality of moving bodies moving in different directions are detected by the plurality of detection units. The optical encoder according to claim 1 or 2,
The received light signal processor is
An optical encoder comprising: a subtracting circuit that subtracts the plurality of received light signals to generate an output signal including a plurality of signal components having different phases and different signal levels with respect to a predetermined threshold level. The optical encoder according to claim 1 or 2,
The received light signal processor is
An exclusive OR circuit that calculates the exclusive OR of the first and second signals whose phases obtained from the plurality of received light signals are 90 ° different from each other and outputs a third signal;
An AND circuit that calculates a logical product of the third signal output from the exclusive OR circuit and one of the first and second signals and outputs a fourth signal;
An optical encoder comprising: a subtracting circuit that subtracts a fourth signal output from the AND circuit from the other of the first and second signals and outputs a fifth signal. The optical encoder according to claim 3 or 4,
The received light signal processor is
An optical encoder comprising: a comparator that compares a signal output from the subtracting circuit with a predetermined reference voltage and outputs a comparison result. The optical encoder according to claim 4, wherein
The received light signal processor is
An optical encoder comprising a negative feedback circuit including an operational amplifier in which a fifth signal output from the subtracting circuit is input to an inverting input terminal and a predetermined reference voltage is input to a non-inverting input terminal. The optical encoder according to claim 5, wherein
The received light signal processor is
An optical encoder comprising a reference voltage unit capable of changing a value of the predetermined reference voltage. The optical encoder according to any one of claims 1 to 7,
The received light signal processor is
An optical encoder having an analog signal generation circuit for generating an analog signal and outputting an output signal including an analog signal component generated by the analog signal generated by the analog signal generation circuit. The optical encoder according to claim 8, wherein
The received light signal processor is
A digital signal generation circuit that generates a digital signal from the received light signal that has a phase different from that of the analog signal generated by the analog signal generation circuit;
An optical encoder comprising: a subtracting circuit that subtracts the analog signal and the digital signal to generate an output signal including a plurality of signal components having different phases and different signal levels with respect to a predetermined threshold level. .   An optical encoder according to claim 1, wherein an output signal including a plurality of signal components having different phase levels and different signal levels with respect to a predetermined threshold level output from the received light signal processing unit, and corresponding to the threshold level An electronic apparatus comprising a comparison unit that compares a reference voltage and outputs the comparison result.   An optical encoder comprising the optical encoder according to claim 8 or 9, wherein the output signal including the analog signal component output from the light receiving signal processing unit is compared with a plurality of different reference voltages, and a plurality of digital signals are obtained as a result of the comparison. An electronic apparatus comprising a comparison unit that outputs   An electronic apparatus comprising the optical encoder according to any one of claims 1 to 9.

Images