WO2015162987A1 - 光学式エンコーダ - Google Patents
光学式エンコーダ Download PDFInfo
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- WO2015162987A1 WO2015162987A1 PCT/JP2015/054864 JP2015054864W WO2015162987A1 WO 2015162987 A1 WO2015162987 A1 WO 2015162987A1 JP 2015054864 W JP2015054864 W JP 2015054864W WO 2015162987 A1 WO2015162987 A1 WO 2015162987A1
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- light receiving
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- optical encoder
- photodiode
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- 230000003287 optical effect Effects 0.000 title claims abstract description 88
- 238000001514 detection method Methods 0.000 claims abstract description 56
- 230000003111 delayed effect Effects 0.000 claims abstract description 14
- 238000010586 diagram Methods 0.000 description 16
- 239000003990 capacitor Substances 0.000 description 8
- 230000007274 generation of a signal involved in cell-cell signaling Effects 0.000 description 8
- 238000000034 method Methods 0.000 description 6
- 230000007257 malfunction Effects 0.000 description 4
- 230000007423 decrease Effects 0.000 description 3
- 238000013041 optical simulation Methods 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 239000000470 constituent Substances 0.000 description 1
- 230000001934 delay Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
- G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
- G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
- G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
- H03K17/94—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the way in which the control signals are generated
- H03K17/941—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the way in which the control signals are generated using an optical detector
- H03K17/943—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the way in which the control signals are generated using an optical detector using a plurality of optical emitters or detectors, e.g. keyboard
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
- G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
- G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
- G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
- G01D5/347—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells using displacement encoding scales
- G01D5/34707—Scales; Discs, e.g. fixation, fabrication, compensation
- G01D5/34715—Scale reading or illumination devices
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
- G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
- G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
- G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
- G01D5/36—Forming the light into pulses
- G01D5/363—Direction discrimination
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K2217/00—Indexing scheme related to electronic switching or gating, i.e. not by contact-making or -breaking covered by H03K17/00
- H03K2217/94—Indexing scheme related to electronic switching or gating, i.e. not by contact-making or -breaking covered by H03K17/00 characterised by the way in which the control signal is generated
- H03K2217/941—Indexing scheme related to electronic switching or gating, i.e. not by contact-making or -breaking covered by H03K17/00 characterised by the way in which the control signal is generated using an optical detector
- H03K2217/94102—Indexing scheme related to electronic switching or gating, i.e. not by contact-making or -breaking covered by H03K17/00 characterised by the way in which the control signal is generated using an optical detector characterised by the type of activation
- H03K2217/94108—Indexing scheme related to electronic switching or gating, i.e. not by contact-making or -breaking covered by H03K17/00 characterised by the way in which the control signal is generated using an optical detector characterised by the type of activation making use of reflection
Definitions
- the present invention relates to an optical encoder that uses a light receiving element to detect the position, moving speed, moving direction, and the like of a moving body, and in particular, a printing machine such as a copying machine or a printer, a FA (factory automation) device, a lens in a camera or the like.
- the present invention relates to an optical encoder suitable for use in a focus adjustment device, a vehicle speed detection device for detecting the rotation angle, speed, etc. of a crankshaft. About.
- Patent Document 1 Japanese Patent Laid-Open No. 59-402578
- a differential output between photodiodes arranged in a light projecting portion and a light shielding portion of a moving body is used.
- the position of the moving body, the moving speed, and the like are detected.
- Patent Document 2 Japanese Patent Laid-Open No. 2013-195180 describes an optical encoder in which the concave portion of the concave and convex portion of the detected object is larger than 1 ⁇ 2 of the convex portion.
- Patent Document 3 Japanese Patent Laid-Open No. 2014-2078 describes an optical encoder that has a photodiode resolution switching function and changes a reference voltage in accordance with switching.
- Patent Document 4 Japanese Patent Laid-Open No. 2007-17390 describes an optical encoder that digitally outputs the outputs of adjacent photodiodes and outputs the rotation and moving direction of the moving body in the order of detection of the digital signals. ing.
- the conventional optical encoder has the following problems.
- Patent Document 1 in an optical encoder that detects the moving speed and moving direction of a moving body, a photodiode proportional to the slit width of the moving body is disposed. The direction of movement cannot be detected. That is, there is a problem that the detection accuracy depends on the accuracy of the moving body slit width.
- Patent Document 4 As a method that does not depend on the slit width of the moving body, there is a detection method using infrared radiation as shown in Patent Document 4. Although this method does not depend on the slit width, the resolution varies depending on the threshold level to be set, so that a large characteristic variation occurs due to variations in optical conditions. While other precedents perform differential operations between two photodiodes, processing is performed with a single photodiode, and thus there is a possibility that a malfunction occurs in detection of the moving direction.
- an object of the present invention is to maintain a high S / N ratio (signal-to-noise ratio) without depending on the resolution of the slits and the reflection area of the moving body, and without depending on variations in the optical system.
- An object of the present invention is to provide an optical encoder capable of detecting a body position, a moving speed, and the like.
- an optical encoder of the present invention is First, second, and third light receiving elements disposed adjacently and sequentially; A detection trigger is output when the output level of the second light receiving element, whose incident light is delayed, is higher than the output level of the first light receiving element preceded by the incident light. On the other hand, a detection signal that outputs a non-detection trigger when the output level of the third light receiving element that is delayed in light input from the second light receiving element is higher than the output level of the second light receiving element. And a generation unit.
- the optical encoder of one embodiment is A light emitting element having an optical axis substantially overlapping the optical axis of the second light receiving element; And a window for narrowing the light receiving openings of the first and third light receiving elements.
- the areas of the light receiving portions of the first, second and third light receiving elements are substantially the same.
- Two sets of the first, second and third light receiving elements are juxtaposed.
- the optical encoder of one embodiment is A capacitance connectable in parallel to each of the first, second and third light receiving elements via a switch; A switch control circuit for controlling the switch.
- the electronic device of this embodiment is The above-described optical encoder is provided.
- the S / N ratio (signal-to-noise ratio) can be kept high without depending on the resolution of the slit of the moving body or the reflection area, and not depending on the variation of the optical system, and the accuracy is high.
- the position of the moving body, the moving speed, etc. can be detected.
- FIGS. 1-1 and 1-2 are diagrams showing the relationship between the arrangement of photodiodes and fluctuations in the amount of received light in the optical encoder according to the first embodiment of the present invention, and FIG. FIG. 1-2 shows a case where the distance between the moving body and the window is smaller than that in FIG. 1-1.
- FIGS. 2-1 and 2-2 are diagrams showing optical simulation results of the amounts of light received by the first to third photodiodes when the distance between the first to third photodiodes and the moving body is 4 mm. It is.
- FIGS. 3A and 3B are diagrams showing optical simulation results of the received light amounts of the first to third photodiodes when the distance between the first to third photodiodes and the moving body is 8 mm. It is.
- FIGS. 5-1, 5-2,..., 5-5 show the waveforms of the respective parts of the optical encoder according to the first embodiment of the present invention, and FIG. 5-1 shows the waveforms from the first to third photodiodes.
- Fig. 5-2 shows a set signal
- Fig. 5-3 shows a reset signal
- Fig. 5-4 shows an output waveform of the RS flip-flop
- Fig. 5-5 shows an input (input photocurrent). Indicates the output voltage from the logic circuit.
- FIGS. 5-1, 5-2,..., 5-5 show the waveforms of the respective parts of the optical encoder according to the first embodiment of the present invention
- FIG. 5-1 shows the waveforms from the first to third photodiodes.
- Fig. 5-2 shows a set signal
- Fig. 5-3 shows a reset signal
- Fig. 5-4 shows an output waveform of the RS flip-flop
- Fig. 5-5 shows an input (input photocurrent). Indicates the output voltage from
- 7A and 7B are diagrams for explaining that the output intersection does not change even when the incident light amount changes. It is a block diagram of the principal part of the optical encoder of 2nd Embodiment of this invention. It is a block diagram of the principal part of the optical encoder of 3rd Embodiment of this invention. It is a wave form diagram for demonstrating operation
- first, second, and third photodiodes A, B, and C as an example of the first, second, and third light receiving elements are parallel to the moving body 10 and the moving body. They are arranged at equal intervals in order in the 10 movement directions.
- the first, second and third photodiodes A, B and C are arranged at the same pitch Z.
- the areas of the light receiving portions of the first, second, and third photodiodes A, B, and C are substantially the same.
- a light emitting diode (LED) 5 as an example of a light emitting element is disposed on the opposite side of the moving body 10 with respect to the second photodiode B, and the light axis of the light emitting diode 5 is the light of the second photodiode B. It almost overlaps the shaft.
- a light shielding plate (not shown) so that the direct light from the LED 5 does not enter the first, second and third photodiodes A, B and C and the reflected light of the moving body 10 can be detected.
- a window portion 7 is provided between the movable body 10 and the first, second and third photodiodes A, B, and C.
- the window portion 7 overlaps a part of the light receiving openings of the first and third photodiodes A and C in the optical axis direction, and narrows the light receiving openings of the first and third photodiodes A and C. .
- the moving body 10 has reflection areas 11 and transmission areas 12 alternately at equal intervals.
- the reflective region 11 and the transmissive region 12 have the same length X in the moving direction.
- the optical encoder of the first embodiment is a reflective encoder, but in the case of a transmissive encoder, although not shown, if a light emitting diode is provided on the opposite side of the first embodiment with respect to the moving body. Good.
- L1 is the distance between the lower surface of the moving body 10 and the upper end surface of the window portion 7
- Y is the top of the first, second and third photodiodes A, B, C.
- the distance between the plane passing through the end face and the plane passing through the upper end face of the window portion 7 is Q1.
- the reflected light from the reflection region 11 begins to enter the first photodiode A and then moves as the moving body 10 moves.
- the distance L2 between the moving body 10 and the window portion 7 is smaller than the distance L1 between the moving body 10 and the window portion 7 in FIG. 1-1.
- Q2 is a period from when the reflected light from the reflective region 11 begins to enter the first photodiode A to when the reflected light from the reflective region 11 enters the second photodiode B as the moving body 10 moves. This represents the moving distance of the reflection region 11 (that is, the moving distance of the moving body 10).
- the components shown in FIG. 1-2 are the same as the components shown in FIG. 1-1. Therefore, the same components are denoted by the same reference numerals, and detailed description thereof is omitted.
- Pi is a predetermined light amount corresponding to the amount of light emitted from the light emitting diode 5
- P1 is a light amount received by the first photodiode A
- P2 is a light amount received by the second photodiode B
- P3 is , Represents the amount of light received by the third photodiode C.
- P1 ′ is the amount of light received by the first photodiode A
- P2 ′ is the amount of light received by the second photodiode B
- P3 ′ is received by the third photodiode C. Represents the amount of light.
- Ts represents a time point when a detection trigger is output
- Te represents a time point when a non-detection trigger is output.
- the amount of received light decreases in inverse proportion to the fourth power of the distances L1 and L2.
- the amount of light is squared until the light passing through the window portion 7 is reflected by the reflection region 11 of the moving body 10. Since it decreases in inverse proportion to the square from the point reflected by the reflection region 11 to the window portion 7, it is inversely proportional to the fourth power of the distances L1 and L2. This is because it can be assumed to decrease. In this way, a reasonable amount of light corresponding to the actual value can be obtained.
- the reflected light from the reflection region 11 at the right end of the moving body 10 is As indicated by the thin line, the light enters the first photodiode A from the tip of the reflection region 11 through the right corner of the window 7. Thereafter, when the moving body 10 travels a distance Q1. As indicated by the bold line, when light enters the second photodiode B and further moves the moving body 10, the received light amount P2 of the second photodiode B is greater than the received light amount P1 of the first photodiode A. Is higher, that is, it becomes larger. At this time Ts, a detection trigger is output.
- the light reception fluctuation slope from the time when the first and second photodiodes A and B are incident to the time when the maximum reflected light is incident is the end portion and the window of the first and second photodiodes A and B.
- the crossing point between the first and second photodiodes A and B is determined depending on the inclination of the right corner of the section 7.
- the reflection region 11 of the moving body 10 moves in the vicinity of the end of the opening of the window portion 7
- the light reception amount P3 of the third photodiode C exceeds the light reception amount P2 of the second photodiode B, That is, the non-detection trigger Te is output at the time Te when the curves P2 and P3 intersect.
- the light reception fluctuation inclination from the time when the second and third photodiodes B and C are incident to the time when the maximum reflected light is incident is the end and window of the second and third photodiodes B and C.
- the crossing point between the second and third photodiodes B and C is determined depending on the inclination of the left corner of the section 7.
- the amount of light reflected from the central portion of the moving body 10 is also incident and affects received light fluctuations, so that X is preferably wider than the window width.
- the distance L2 between the moving body 10 and the first, second, and third photodiodes A, B, and C is larger than the distance L1 shown in FIG. Even when it becomes smaller, a pulse signal corresponding to the width X of the reflection region 11 can be obtained as in FIG. 1-1. This is because the amount of light received is inversely proportional to the fourth power of the distance.
- the amount of light received by the first, second, and third photodiodes A, B, and C increases, but the first, second, and second
- the light receiving fluctuation inclination from the time when the three photodiodes A, B, and C are incident to the time when the maximum reflected light is incident is the end portion of the first, second, and third photodiodes A, B, and C and the window portion 7. This is because there is no change in the intersections Ts and Te of the received light signals.
- P1 ', P2', and P3 ' correspond to P1, P2, and P3 in FIG. 1-1.
- FIG. 2 shows a case where the distance between the moving body 10 and the first, second, and third photodiodes A, B, and C is 4 mm.
- FIGS. In this case, the distance between the second and third photodiodes A, B, and C is 8 mm.
- the size of the moving body 10 is 100 mm wide.
- the broken line indicates the amount of light incident on the first photodiode A
- the solid line indicates the amount of light incident on the second photodiode B
- the alternate long and short dash line indicates the third amount. Represents the amount of light incident on the photodiode C.
- the SN ratio can be kept high without depending on the variation of the optical system, the position of the moving body, the moving speed, etc. can be maintained with high accuracy. It can be detected.
- FIG. 4 is a diagram showing a circuit configuration of the optical encoder according to the first embodiment.
- this optical encoder includes two comparators 21 and 22 and a logic circuit 30, as shown in FIG.
- the two comparators 21 and 22 and the logic circuit 30 constitute a detection signal generation unit 50 and output an output voltage shown in FIG. 5-5 as described later.
- the rising edge of the output voltage in FIG. 5-5 corresponds to the detection trigger Ts, and the falling edge of the output voltage corresponds to the non-detection trigger Te.
- the comparator 21 receives the output A of the first photodiode A at the + terminal and receives the output B of the second photodiode B at the ⁇ terminal.
- the set signal (SET) Is output.
- the comparator 22 receives the output C of the third photodiode C at the + terminal and receives the output B of the second photodiode B at the ⁇ terminal.
- the reset signal ( RSET) is output.
- the outputs of the first photodiode A, the second photodiode B, and the third photodiode C are represented by outputs P1, P2, and P3, respectively.
- they are represented as outputs A, B, and C. This is because the relationship between the first photodiode A and the output A is easy to understand and there is no possibility of confusion.
- output P1 output A
- output P2 output B
- output P3 output C. The same applies hereinafter.
- the outputs A, B, and C of the first, second, and third photodiodes A, B, and C are represented by curves A, B, and C in FIG.
- the set signal output from the comparator 21 is represented by a curve in FIG. 5-2, while the reset signal output from the comparator 22 is represented by a curve in FIG. 5-3.
- the logic circuit 30 has, for example, the configuration shown in FIG. 6 and includes an RS flip-flop 31, an inverter 32, an amplifier 33, and an AND gate 35.
- the output of the inverter 32 is obtained by inverting the set signal shown in FIG.
- the AND gate 35 is a logic between the output of the RS flip-flop 31 shown in FIG. 5-4 output from the amplifier 33 and the inverted signal of the set signal of FIG. 5-2 output from the inverter 32.
- the product is taken to output the output voltage shown in FIG. 5-5.
- the detection signal generator 50 outputs the output voltage of FIG. 5-5, and outputs the detection trigger Ts that is the rise of the output voltage and the non-detection trigger Te that is the fall of the output voltage. can do.
- the detection signal generation unit 50 outputs the second photodiode B whose light is delayed from the first photodiode A with respect to the output level A of the first photodiode A preceded by the light.
- the detection trigger Ts is output, while the incident light of the third photodiode C whose light input is delayed from the output level B of the second photodiode B is delayed from that of the second photodiode B.
- the output level C exceeds, the non-detection trigger Te is output.
- this optical encoder does not depend on the resolution such as the slit width of the moving body 10 and does not depend on the variation of the optical system, so that the SN ratio can be kept high, and the position of the moving body 10 can be maintained with high accuracy.
- the moving speed can be detected.
- a light emitting diode 5 having an optical axis substantially overlapping with the optical axis of the second photodiode B is provided, and the first is located in the center. Since the light receiving openings of the first and third photodiodes A and C located at both ends are provided without restricting the light receiving openings of the second photodiode B, the second photodiode B is provided. Of the first and third photodiodes A and C can be obtained stably and reliably at the intersections Ts and Te. Therefore, the detection trigger Ts and the non-detection trigger can be obtained. Te can be obtained with certainty, does not depend on the resolution of the moving body 10 such as the slit width, and does not depend on variations in the optical system. Position, moving speed Or the like can detect.
- the areas of the light receiving portions of the first, second, and third photodiodes A, B, and C are substantially the same, and, as shown in FIG. Because differential operation is performed, common-mode noise can be reduced, which is beneficial.
- the intersection Ts between the output A of the first photodiode A and the output B of the second photodiode B is used as the detection trigger Ts. Since the intersection Te of the output B of the second photodiode B and the output C of the third photodiode C is used as the non-detection trigger Te, for example, from the state of A ⁇ B shown in FIG. Even if the incident light quantity varies in the state of A> B shown in 7-2, the intersections Ts and Te are not affected. Therefore, malfunction can be suppressed and the position, moving speed, etc. of the moving body 10 can be detected accurately.
- the third photodiode C in FIG. The state in which the attenuation of the received light amount is delayed, the state in which the received light amount is reversed between the second and third photodiodes B and C in the absence of a reflecting object, and the like occur. It cannot be detected.
- the output of the RS flip-flop 31 that receives the set signal (SET) and the reset signal (RSET), the inverted signal of the set signal (SET) by the inverter 32, and Is obtained by the AND gate 35 and the intersections Ts and Te are detected.
- the movement is accurately performed without being influenced by disturbance light.
- the position, moving speed, etc. of the body 10 can be detected.
- the reflection region (reflection detection object) 11 is provided on the second photodiode B. This is because, when facing each other, a current with an output B exceeding outputs A and C is obtained.
- the optical encoder of the second embodiment is different from the first embodiment only in the configuration of the logic circuit 130 shown in FIG. Therefore, regarding the second embodiment, the configuration and operation other than the logic circuit 130 are described with reference to FIGS. 1-1, 1-2,..., 7-1, 7-2. The description is omitted.
- the logic circuit 130 according to the second embodiment shown in FIG. 8 differs from the logic circuit 30 according to the first embodiment shown in FIG. 6 in that two inverters 321 and 321 are connected in series in the subsequent stage of the inverter 32 that receives the set signal (SET). The only difference is that the transmission of the signal is delayed by the inverters 321 and 322 by connecting the H.322.
- the logic circuit 130 of the second embodiment can input the input from the RS flip-flop 31 to the AND gate 35 via the amplifier 33 and the AND gate of the set signal via the inverters 32, 321 and 322.
- the delay difference from the input to 35 is suppressed from increasing.
- FIG. 9 is a block diagram showing a main part of the third embodiment.
- the third embodiment is different from the first embodiment only in the light path from the light emitting diode 5 to the first photodiode A, the second photodiode B, and the third photodiode C. There is no difference.
- (Fourth embodiment) 10 and 11 are graphs for explaining the operation of the optical encoder of the fourth embodiment.
- the optical encoder of the fourth embodiment is not shown, but the set of the first photodiode A, the second photodiode B, and the third photodiode C shown in FIG.
- the detection signal generation unit 50 shown in FIG. 4 is provided for each set in parallel in the photodiode arrangement direction.
- each set of outputs may be subjected to signal processing in a time division manner by one detection signal generation unit.
- Output 1 and output 2 are at the H (high) level.
- the output changes from L to H in the order of output 1 and output 2.
- the phase difference between output 1 and output 2 is 90 °.
- the moving direction of the moving body 10 can be easily detected by detecting the order of L ⁇ H of the output 1 and the output 2.
- FIG. 12 is a block diagram of an optical encoder according to the fifth embodiment.
- the optical encoder of the fifth embodiment is different from the optical encoder of the third embodiment shown in FIG. 9 in each of the first photodiode A, the second photodiode B, and the third photodiode C.
- Capacitors 61, 62, 63 are connected in parallel via switches 71, 72, 73, and the switch 71, 72, 73 is only provided with a switch control circuit 80 that receives and controls signals from the logic circuit 30.
- the same reference numerals are given to the same components as those of the third embodiment shown in FIG. 9, and the description thereof is omitted.
- the switch control circuit 80 In response to a signal from the logic circuit 30, the switch 72 is controlled so as to disconnect the second photodiode B from the capacitor 62, and the switch 73 is controlled so that the third photodiode C is connected to the capacitor 63.
- SET set signal
- the switch control circuit 80 is configured such that when the comparator 22 outputs the reset signal (RSET), that is, when the output level C of the third photodiode C falls below the output level B of the second photodiode B.
- RSET reset signal
- the switch 73 is controlled so that the third photodiode C is disconnected from the capacitor 63.
- the switches 71, 72, and 73 are controlled by the switch control circuit 80, and the capacitors 61, 62, and so on are connected to the first photodiode A, the second photodiode B, and the third photodiode C, respectively.
- 63 can be connected in parallel to generate a signal delay in the outputs A to C, thereby reliably generating the intersections of the outputs A to C of the first to third photodiodes A to C.
- the method of delaying the outputs A to C of the first to third photodiodes A to C is not limited to the above-described method of connecting the capacitors, and any method can be used as long as the capacitors are connected at an appropriate timing. It may be anything.
- FIG. 13 is a block diagram of an optical encoder according to the sixth embodiment.
- the optical encoder of the sixth embodiment shown in FIG. 13 differs from the optical encoder of the third embodiment shown in FIG. 9 in place of the comparators 21 and 22 of the third embodiment, The only difference is that the comparators 212 and 222 are used.
- FIG. 13 the same reference numerals are assigned to the same components as those of the third embodiment shown in FIG. 9, and the description thereof is omitted.
- the sub-comparator 212 receives the output A of the first photodiode A at the + terminal, receives the output B of the second photodiode B at the ⁇ terminal, and H (high level) when A> B. ) Signal is output to activate the main comparator 211, while when A ⁇ B, an L (low level) signal is output to stop the operation of the main comparator 211.
- the switching between the H signal and the L signal of the sub-comparator 212 is switched with a certain hysteresis.
- the main comparator 211 receives the output B of the second photodiode B at the + terminal and receives the output A of the first photodiode A at the ⁇ terminal.
- a ⁇ B the H signal
- a set signal (SET) that becomes an L signal is output.
- the sub-comparator 222 receives the output B of the second photodiode B at the + terminal and receives the output C of the third photodiode C at the ⁇ terminal.
- B> C the H signal Is output to start the main comparator 221
- B ⁇ C the L signal is output to stop the operation of the main comparator 221.
- the switching between the H signal and the L signal of the sub-comparator 222 is switched with a certain hysteresis.
- the main comparator 221 receives the output C of the third photodiode C at the + terminal and receives the output B of the second photodiode B at the ⁇ terminal.
- B ⁇ C the H signal
- RSET reset signal
- the set time is set for a short period corresponding to the hysteresis period of the sub-comparators 212 and 222.
- a signal (SET) and a reset signal (RSET) are output.
- the electronic device of the seventh embodiment detects, for example, a printing device such as a copying machine or a printer, a FA (factory automation) device, a lens focus adjustment device in a camera, a rotation angle of a crankshaft, a speed, or the like.
- a vehicle speed detection device or the like including the optical encoders of the first to sixth embodiments.
- This electronic device can maintain a high S / N ratio (signal-to-noise ratio) without depending on the resolution of the slit or reflection area of the moving body, and without depending on variations in the optical system. Since the optical encoder capable of detecting the moving speed and the like is included, the performance is extremely good.
- a photodiode is used as an example of the light receiving element, but any element may be used as long as it can detect light such as a phototransistor.
- the light emitting element is not limited to an LED, and any element may be used as long as it can emit light such as a semiconductor laser.
- the configurations of the detection signal generation unit 50 and the logic circuit 30 are not limited to the above-described embodiment, and various configurations are possible.
- the logic circuit can be configured by combining logic elements such as a NAND gate and a NOR gate.
- a JK flip-flop may be used.
- an optical encoder of the present invention is First, second and third light receiving elements A, B, C arranged in order adjacent to each other; When the output level B of the second light receiving element B, which is delayed from the first light receiving element A, is higher than the output level A of the first light receiving element A preceded by the incident light, While outputting the detection trigger Ts, the output level C of the third light receiving element C in which the incident light is delayed from the second light receiving element B is higher than the output level B of the second light receiving element B.
- a detection signal generation unit 50 that outputs a non-detection trigger Te is provided.
- the detection signal generation unit 50 delays the incident light from the first light receiving element A than the output level A of the first light receiving element A preceded by the incident light.
- the detection trigger Ts is output, while the incident light is delayed from the output level B of the second light receiving element B than the second light receiving element B.
- the output level C of the third light receiving element C exceeds, the non-detection trigger Te is output.
- this optical encoder does not depend on the resolution such as the slit width of the moving body 10 and does not depend on the variation of the optical system, so that the SN ratio can be kept high, and the position of the moving body 10 can be maintained with high accuracy.
- the moving speed can be detected.
- the intersection Ts between the output A of the first light receiving element A and the output B of the second light receiving element B is used as the detection trigger Ts, while the output B of the second light receiving element B is used.
- the output C of the third light receiving element C are used as the non-detection trigger Te, so that the intersections Ts and Te are not affected even if the incident light quantity varies due to disturbance light. Therefore, malfunction can be suppressed and the position, moving speed, etc. of the moving body 10 can be detected accurately.
- the optical encoder of one embodiment is A light emitting element 5 having an optical axis substantially overlapping the optical axis of the second light receiving element B; And a window 7 for narrowing the light receiving openings of the first and third light receiving elements A and C.
- the areas of the light receiving portions of the first, second, and third light receiving elements A, B, and C are substantially the same.
- the common mode noise can be reduced, It is beneficial.
- Two sets of the first, second, and third light receiving elements A, B, and C are juxtaposed.
- the moving direction of the moving body 10 can be easily detected by detecting the order of L ⁇ H (or H ⁇ L) of the two sets of outputs.
- the optical encoder of one embodiment is Capacitors 61, 62, 63 that can be connected in parallel to the first, second, and third light receiving elements A, B, C via switches 71, 72, 73, respectively. And a switch control circuit 80 for controlling the switches 71, 72, 73.
- the switches 71, 72, and 73 are controlled by the switch control circuit 80, and the capacitance 61 is provided for each of the first light receiving element A, the second light receiving element B, and the third light receiving element C. , 62, 63 are connected in parallel to generate a signal delay in the outputs A to C, and to reliably generate the intersections of the outputs A to C of the first to third light receiving elements A to C. it can.
- the electronic device of this embodiment is The above-described optical encoder is provided.
- This electronic device does not depend on the resolution of the slit or reflection area of the moving body and does not depend on variations in the optical system, and can maintain a high S / N ratio, with high accuracy, and the position, moving speed, etc. of the moving body. Since the optical encoder capable of detection is included, the performance is extremely good.
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Abstract
Description
に関する。
隣接して順に配置された第1、第2および第3の受光素子と、
入光が先行する上記第1の受光素子の出力レベルよりも、その第1の受光素子よりも入光が遅延する上記第2の受光素子の出力レベルが上回ったときに、検知トリガを出力する一方、上記第2の受光素子の出力レベルよりも、上記第2の受光素子よりも入光が遅延する上記第3の受光素子の出力レベルが上回ったときに、非検知トリガを出力する検知信号生成部と
を備えることを特徴としている。
上記第2の受光素子の光軸と略重なる光軸を有する発光素子と、
上記第1および第3の受光素子の受光開口部を絞る窓部と
を備える。
上記第1、第2および第3の受光素子の受光部の面積が略同一である。
上記第1、第2および第3の受光素子の組を、2組並置している。
上記第1、第2および第3の受光素子の夫々にスイッチを介して並列に接続可能な容量と、
上記スイッチを制御するスイッチ制御回路と
を備える。
上述の光学式エンコーダを備える。
図1-1に示すように、第1、第2および第3の受光素子の一例としての第1、第2および第3のフォトダイオードA,B,Cを移動体10に平行に、移動体10の移動方向に、順に等間隔に配置している。上記第1、第2および第3のフォトダイオードA,B,Cは、同一のピッチZで配列している。上記第1、第2および第3のフォトダイオードA,B,Cの受光部の面積は略同一である。
P1=Pi/L1^4
P1’=Pi/L2^4
となる。
L1:Y=Q1:Z → Q1=L1*Z/Y
L2:Y=Q2:Z → Q2=L2*Z/Y
となる。
この第2実施形態の光学式エンコーダは、図8に示す論理回路130の構成のみが、第1実施形態と異なる。したがって、第2実施形態について、上記論理回路130以外の構成、作用については、図1-1,1-2,…,7-1,7-2の第1実施形態の説明を援用して、その説明は省略する。
図9は、第3実施形態の要部を示すブロック図である。
図10および11は、第4実施形態の光学式エンコーダの動作を説明するためのグラフである。
図12は、第5実施形態の光学式エンコーダのブロック図である。
図13は、第6実施形態の光学式エンコーダのブロック図である。
第7実施形態の電子機器は、図示しないが、例えば、複写機、プリンターなどの印刷機器、FA(ファクトリオートメーション)機器、カメラ等におけるレンズフォーカス調整装置、クランクシャフトの回転角、速度等を検出する車用速度検出装置等であって、第1~第6実施形態の光学式エンコーダを備えている。
隣接して順に配置された第1、第2および第3の受光素子A,B,Cと、
入光が先行する上記第1の受光素子Aの出力レベルAよりも、その第1の受光素子Aよりも入光が遅延する上記第2の受光素子Bの出力レベルBが上回ったときに、検知トリガTsを出力する一方、上記第2の受光素子Bの出力レベルBよりも、上記第2の受光素子Bよりも入光が遅延する上記第3の受光素子Cの出力レベルCが上回ったときに、非検知トリガTeを出力する検知信号生成部50と
を備えることを特徴としている。
上記第2の受光素子Bの光軸と略重なる光軸を有する発光素子5と、
上記第1および第3の受光素子A,Cの受光開口部を絞る窓部7と
を備える。
上記第1、第2および第3の受光素子A,B,Cの受光部の面積が略同一である。
上記第1、第2および第3の受光素子A,B,Cの組を、2組並置している。
上記第1、第2および第3の受光素子A,B,Cの夫々にスイッチ71,72,73を介して並列に接続可能な容量61,62,63と、
上記スイッチ71,72,73を制御するスイッチ制御回路80と
を備える。
上述の光学式エンコーダを備える。
7 窓部
10 移動体
21,22,211,212,221,222 コンパレータ
30,130 論理回路
50 検知信号生成部
61,62,63 容量
71,72,73 スイッチ
80 スイッチ制御回路
A 第1の受光素子
B 第2の受光素子
C 第3の受光素子
Ts 検知トリガ
Te 非検知トリガ
Claims (5)
- 隣接して順に配置された第1、第2および第3の受光素子と、
入光が先行する上記第1の受光素子の出力レベルよりも、その第1の受光素子よりも入光が遅延する上記第2の受光素子の出力レベルが上回ったときに、検知トリガを出力する一方、上記第2の受光素子の出力レベルよりも、上記第2の受光素子よりも入光が遅延する上記第3の受光素子の出力レベルが上回ったときに、非検知トリガを出力する検知信号生成部と
を備えることを特徴とする光学式エンコーダ。 - 請求項1に記載の光学式エンコーダにおいて、
上記第2の受光素子の光軸と略重なる光軸を有する発光素子と、
上記第1および第3の受光素子の受光開口部を絞る窓部と
を備えることを特徴とする光学式エンコーダ。 - 請求項1または2に記載の光学式エンコーダにおいて、
上記第1、第2および第3の受光素子の受光部の面積が略同一であることを特徴とする光学式エンコーダ。 - 請求項1から3のいずれか1つに記載の光学式エンコーダにおいて、
上記第1、第2および第3の受光素子の組を、2組並置していることを特徴とする光学式エンコーダ。 - 請求項1から4のいずれか1つに記載の光学式エンコーダにおいて、
上記第1、第2および第3の受光素子の夫々にスイッチを介して並列に接続可能な容量と、
上記スイッチを制御するスイッチ制御回路と
を備えることを特徴とする光学式エンコーダ。
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