JP2019174260A - Encoder - Google Patents

Abstract

Provided is an encoder for detecting displacement in two axes, which enables space saving. An encoder according to an embodiment of the present invention includes a first scale in which light reflecting portions and light transmitting portions are arranged alternately and continuously, and is relatively movable with respect to the first scale. The first light detecting unit 20 includes a first light emitting unit 24 that irradiates light, and a first light receiving unit 26 that receives the light reflected and returned by the first scale, converts the light into an electric signal, and outputs the electric signal. A second light-emitting unit that includes a first light detection unit and a second light-emitting unit that is superimposed on the first scale and emits light of a pattern at a predetermined interval. A second scale extending in a direction intersecting with the light transmitting section, and a second light detecting section 22 movable relative to the second scale, and receives light from the second scale and converts the light into an electric signal. A second photodetector having a second light receiving means for outputting the second light; And a part. [Selection] Figure 2

Description

  The present invention relates to an encoder for detecting displacement, and more particularly to an encoder that can be used for detecting displacement in two axial directions.

  2. Description of the Related Art Conventionally, optical encoders (hereinafter simply referred to as encoders) that can measure dimensions and the like with high accuracy have been used in the field of measuring instruments and the like. The encoder measures the length and angle by reading the equally spaced pattern generated on the scale surface with a reading head (light detection unit) and counting the number of patterns that have passed over the reading head.

  As such an encoder, a one-dimensional encoder for measuring a relative displacement amount in a linear direction is widely known and used. Since this one-dimensional encoder can be used for displacement measurement in the linear direction, for example, by using two one-dimensional encoders, two-dimensional displacement measurement can be performed.

  Patent Document 1 discloses an example of a two-dimensional encoder. The two-dimensional encoder of Patent Document 1 includes a collimator lens that converts light from a light source into parallel light, a plane mirror that reflects parallel light from the collimator lens to change the optical path, and light from the plane mirror at predetermined intervals. Transmits through the main scale that transmits through the array of lattice patterns, the X-axis index scale and the Y-axis index scale formed on the base material that transmits light from the main scale, and the X-axis index scale. X-axis photodetector that detects the converted light and converts it into an electrical signal, Y-axis photodetector that detects the light transmitted through the Y-axis index scale and converts it into an electrical signal, and the X-axis and Y-axis And a signal processing unit to which an electric signal from the axial photodetector is input. In this two-dimensional encoder, an X-axis index scale is formed on one surface of the base material and a Y-axis index scale is formed on the other surface of the base material. The axial index scale is formed so as not to overlap with the plane mirror.

JP 2003-307439 A Japanese Patent No. 6108898

  In the two-dimensional encoder of Patent Document 1, light from one light source is applied to the X-axis index scale and the Y-axis index scale at a position away from the X-axis index scale. Therefore, it is necessary to increase the base material or the main scale on which these two index scales are formed to some extent. For this reason, the two-dimensional encoder of Patent Document 1 is not suitable for measuring a displacement amount in a minute region in a small machine or apparatus.

  An object of the present invention is to provide an encoder for detecting displacement in two axial directions that enables space saving.

  In order to solve the above problems, according to one embodiment of the present invention, a first scale in which light non-transmitting portions (light reflecting portions) and light transmitting portions are alternately and continuously arranged and relative to the first scale is provided. First light detector that is movable, and is reflected by the light non-transmissive portion of the first scale due to light irradiation from the first light emitting means for irradiating the first scale with light The first light detector includes a first light receiving unit that receives the light that has returned and the light that has passed through the first scale, converts the light into an electrical signal, and outputs the electrical signal. The first light detection unit is superimposed on the first scale. The second scale includes a second light emitting unit capable of emitting a stripe pattern having a predetermined interval, and the stripe pattern extends in a direction intersecting the light reflecting portion and the light transmitting portion of the first scale. , Second scale and relative to said second scale Provided is an encoder comprising a movable second light detection unit, the second light detection unit including a second light receiving unit that receives light from the second scale, converts the light into an electric signal, and outputs the electric signal. .

  Preferably, the second scale is configured to transmit light from the first light emitting means, and extends between the first scale and the first light detection unit. Alternatively, the first scale may be provided so as to extend between the second scale and the first light detection unit.

  Preferably, the second light emitting means is configured to emit light of the striped pattern extending in a direction orthogonal to the light reflecting portion and the light transmitting portion of the first scale.

  According to the encoder according to one aspect of the present invention, it is possible to detect a displacement in two axial directions and to save space.

It is a schematic block diagram of the probe to which the encoder which concerns on one Embodiment of this invention was applied. It is a schematic block diagram of the encoder of one Embodiment of this invention. FIG. 3 is a schematic cross-sectional view of a part of the scale of the encoder of FIG. 2 centering on a second scale. FIG. 3 is a diagram for explaining a relationship between a first scale and a second scale of the encoder of FIG. 2, (a) shows a part of a light reflecting part and a light transmitting part of the first scale, and (b) shows a first part. The organic EL element and separator of a part of 2 scale are shown. FIG. 3 is a schematic diagram illustrating a light pattern on a first light detection unit and a sensor element for detecting the light pattern in the encoder of FIG. 2. 6 is a graph for explaining a processing example in a first light detection unit for the light of FIG. 5.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. Here, in the drawing, portions indicated by the same symbols are similar elements having similar functions.

  FIG. 1 shows a schematic configuration diagram of a probe 1 to which an encoder 10 according to an embodiment of the present invention is applied. FIG. 2 shows a schematic configuration diagram of the encoder 10 of FIG.

  A probe 1 shown in FIG. 1 includes a housing (housing) 3 and a stylus holding member 5 movable with respect to the housing 3. The housing 3 can be attached to a position determining device such as a coordinate measuring machine or machine tool that can move the probe 1 with respect to a workpiece to be measured (not shown). A stylus 5b having a workpiece contact end 5a is attached to the stylus holding member 5. As shown in FIG. 1, the stylus holding member 5 is positioned at an initial position with respect to the housing 3 by the elastic force of the spring members 7a and 7b when the stylus 5b is not in contact with the workpiece or the like. When the stylus 5b is displaced by contact with a workpiece or the like, the stylus holding member 5 is configured to be movable in a two-dimensional plane composed of an X axis and a Y axis here. A ball 9 is disposed on the lower side of the stylus holding member 5 so that the stylus holding member 5 can move in a two-dimensional plane, that is, an XY plane. Although not shown, the stylus holding member 5 is configured not to relatively move in the Z-axis direction orthogonal to the XY plane.

  In order to detect such a displacement of the stylus 5b in the probe 1, an encoder 10 is mounted on the probe 1. The encoder 10 includes a scale 12 and a reading sensor 14. Here, a scale 12 is provided on the stylus holding member 5, and a reading sensor 14 is provided on the housing 3. However, the reading sensor 14 may be provided on the stylus holding member 5 and the scale 12 may be provided on the housing 3. The surface 5s on which the scale 12 of the stylus holding member 5 is provided is formed so as not to reflect or hardly reflect light, and is formed, for example, as a black matte material surface.

  A schematic configuration of the encoder 10 of FIG. 1 is shown in FIG. However, in FIG. 2, the vertical positional relationship between the scale 12 and the reading sensor 14 in the drawing is opposite to that in FIG. As shown in FIG. 2, the scale 12 includes a first scale 16 and a second scale 18. The reading sensor 14 includes a first light detection unit 20 corresponding to the first scale and a second light detection unit 22 corresponding to the second scale.

  Here, the scale 12 will be described first. The first scale 16 is a scale in which light reflecting portions 16a and light transmitting portions 16b as light non-transmitting portions are alternately and continuously arranged. Here, the first scale 16 is formed by depositing a metal with high light reflectance (for example, Cr, Au, Pt, Ag, Al, etc.) on a transparent or light-transmitting glass plate. 16a is formed. That is, the portion where such a metal film is not formed becomes the light transmission portion 16b. Here, each of the light reflecting portion 16a and the light transmitting portion 16b is provided so as to extend in parallel to the Y axis of FIG. Therefore, the first scale 16 has a striped pattern with a predetermined interval.

  A second scale 18 is superimposed on the first scale 16. The second scale 18 has three layers. FIG. 3 shows a schematic cross-sectional view of a part of the scale 12 with the second scale 18 as the center. In the second scale 18, the middle layer (intermediate layer) 18 m in FIGS. 2 and 3 has a configuration in which organic EL elements 18 a and separators 18 b are alternately arranged. The separator 18b is mainly provided between the adjacent organic EL elements 18a. A first electrode layer 18u and a second electrode layer 18v are provided above and below the intermediate layer 18m. In the second scale 18, since no voltage is applied between the electrode layers 18u and 18v, the organic EL element 18a has a light transmittance of a certain degree regardless of whether or not a voltage is applied to the organic EL element 18a. Is made of a permeable material. Therefore, the second scale 18 extending between the first scale 16 and the reading sensor 14 can transmit light from the first light emitting unit 24 described later. Various known materials can be used as the material of the organic EL element 18a, the material of the separator 18b, and the material of the electrode layers 18u and 18v. Here, each of the organic EL element 18a and the separator 18b is provided so as to extend in parallel with the X axis of FIG. Therefore, the second scale 18 can emit a stripe pattern having a predetermined interval. However, the predetermined interval may be the same as or different from the predetermined interval in the first scale 16.

  In the scale 12, the direction in which the light reflecting portion 16 a and the light transmitting portion 16 b in the first scale 16 extend (the Y-axis direction in the present embodiment) is the direction in which the organic EL element 18 a in the second scale 18 extends. The first scale 16 and the second scale 18 are provided with respect to each other so as to intersect with each other (in the present embodiment, the X-axis direction), in particular, at a right angle here. As schematically shown in FIG. 4, a part of the first scale 16 and a part of the second scale 18, the light reflecting part 16 a and the light transmitting part 16 b in the first scale 16 are the organic EL of the second scale 18. It has an orthogonal relationship with the element 18a. Therefore, the second scale 18, that is, the organic EL element 18 a can emit light in a striped pattern extending in a direction intersecting the light reflecting portion 16 a and the light transmitting portion 16 b of the first scale 16, particularly extending in the orthogonal direction. It is. Here, the first scale 16 and the second scale 18 are integrally joined by a known joining means. The light reflecting portion 16a of the first scale 16 is formed on the surface of the first scale 16 opposite to the second scale 18 so as not to be affected by the joining (see FIG. 1). Note that the scale 12 may be configured by simply overlapping the first scale 16 and the second scale 18 without being joined. For example, the second scale 18 may be configured as an organic EL sheet and may simply be superimposed on the first scale 16.

  In the probe 1 of FIG. 1, the reading sensor 14 is provided at a position away from the scale 12 by a predetermined distance. The reading sensor 14 is provided so as to be parallel to the scale 12. As described above, the reading sensor 14 includes the first light detection unit 20 corresponding to the first scale 16 and the second light detection unit 22 corresponding to the second scale 18.

  The first light detection unit 20 corresponding to the first scale 16 forms a part of the reading sensor 14 and is movable relative to the first scale 16. The first light detection unit 20 receives a first light emitting unit (first light emitting unit) 24 for irradiating the first scale 16 with light, receives light reflected from the first scale 16, converts it into an electrical signal, and outputs it. And a first light receiving section (first light receiving means) 26 for performing the above operation. The first light emitting unit 24 can be configured by, for example, a light emitting diode (LED) array, but other light sources such as a semiconductor laser (LD) array may be used. In particular, here, the first light emitting unit 24 is configured to irradiate red light toward the first scale 16. Therefore, the 1st light-receiving part 26 of the 1st light detection part 20 is comprised so that light may be received and the electrical signal according to the component of red light may be output. In addition, the color of the light of the 1st light emission part 24 is not limited to red light.

  For example, the first light receiving unit 26 may include a photodiode (PD) array. Further, an electronic component formed with a circuit for driving the first light emitting unit 24 and a circuit for converting the reflected light from the first scale 16 in the first light receiving unit 26 into an electrical signal, Then, the 1st photon detection part 20 may be provided with the integrated circuit (IC), and this IC may exist separately from the 1st photon detection part 20. FIG.

  On the other hand, the second light detection unit 22 corresponding to the second scale 18 is the same as the first light detection unit 20 corresponding to the first scale 16 in that it can move relative to the second scale 18. However, the second light receiving unit 28 as the second light receiving unit is provided without including the light emitting unit (light emitting unit). This is because the second scale 18 has the organic EL element 18a as the second light emitting means, as can be understood from the above description. The second light emitting means may include a first electrode layer 18u and a second electrode layer 18v in addition to the organic EL element 18a. The organic EL element 18a of the second scale 18 is a self-luminous body and is configured to emit blue light here. Accordingly, the second light receiving unit 28 of the second light detection unit 22 is configured to receive the light from the second scale 18 and convert it into an electrical signal, and in particular to output an electrical signal corresponding to the component of the blue light. Yes.

  Here, a circuit for the second light receiving unit 28 of the second light detecting unit 22 to convert the light from the second scale 18 into an electric signal and process it is integrated with the first light detecting unit 20 and the reading sensor 14 here. They are configured as one electronic component. On the other hand, the electronic component 30 including a circuit for controlling the light emission of the organic EL element 18 a of the second scale 18 as the second light emitting means is configured separately from the reading sensor 14. However, the reading sensor 14 and the electronic component 30 may be integrated.

  Here, displacement detection in the X-axis direction by the first scale 16 and the first light detection unit 20 will be described with reference to FIGS. 2, 5, and 6. In addition, the displacement detection in the Y-axis direction by the second scale 18 and the second light detection unit 22 is performed by detecting the displacement in the X-axis direction by the first scale 16 and the first light detection unit 20, and by the light emitting means. Although there is a difference in arrangement, the processing in the light receiving means is almost the same. Therefore, detailed description of displacement detection in the Y-axis direction by the second scale 18 and the second light detection unit 22 is omitted. In addition, the description of the displacement detection about one axis described below is mainly based on Patent Document 2.

  The first light receiving unit 26 will be described. The first light receiving unit 26 is irradiated from the first light emitting unit 24 to the first scale 16 while passing through the second scale 18, is reflected by the light reflecting unit 16 a, and passes through the second scale 18 again. It is configured to include a PD array for receiving light returned to the one light receiving unit 26 side. This will be described in detail with reference to FIG. FIG. 5 is an explanatory diagram illustrating the first light receiving unit 26. As shown in FIG. 5, the light emitted from the first light emitting unit 24 and reflected by the first scale 16 forms a stripe pattern of a bright part 40 and a dark part 42 on the surface of the first light receiving part 26. The bright portion 40 is a portion corresponding to the light reflected by the light reflecting portion 16a, and the dark portion 42 is a portion corresponding to the light transmitting portion 16b, and is dark because light is not reflected.

  The PD array constituting the first light receiving unit 26 includes a plurality of PD sets each including four PD elements PD1 (symbol 44), PD2 (symbol 46), PD3 (symbol 48), and PD4 (symbol 50). Set exists and is configured. Here, a set of one bright portion 40 and one dark portion 42 is received by four PD elements PD1, PD2, PD3, and PD4. Therefore, it is desirable that the combined size of the bright portion 40 and the dark portion 42 is the same as the combined size of the four PD elements PD1 to PD4.

  At this time, each of the four PD elements outputs an electrical signal whose phase is shifted by ¼ from PD1 to PD4, and each PD of the set of PD elements outputs the same electrical signal to each of PD1 to PD4. . That is, each PD1 of each set of PD elements outputs the same signal, and each PD2 outputs the same signal. This is the same for PD3 and PD4.

  Since the electrical signals whose phases are shifted by 1/4 are output from PD1 to PD4, PD1 and PD3 output electrical signals that are 1/2 or 180 degrees out of phase with each other, and PD2 and PD4 are similarly 180 degrees from each other. Outputs an electrical signal out of phase. For this reason, PD1 of each set of PD elements, PD2, PD3, and PD4 are connected, and an electric signal is output. Furthermore, the difference between the electrical signals of PD1 and PD3 having a phase difference of 180 degrees can be taken as A, and the difference between the electrical signals of PD2 and PD4 can be taken as B. As a result, the electric signal A and the electric signal B are signals whose phases are ¼, that is, 90 degrees.

  Here, further description will be given with reference to FIG. FIG. 6 is an explanatory diagram showing the output electric signals of PD1 to PD4 and the electric signals A and B. As shown in FIG. 6, the waveforms 52 to 58, which are the waveforms of the output electrical signals of PD1 to PD4, are out of phase by 1/4, that is, 90 degrees. That is, the waveform 52 of PD1 and the waveform 54 of PD3 are 180 degrees out of phase, and the waveform 56 of PD2 and the waveform 58 of PD4 are also 180 degrees out of phase. In other words, by taking the difference between the electric signals of PD1 and PD3 that are 180 degrees out of phase, the electric signal A is obtained by inverting and synthesizing the signal of PD3. Similarly, the electric signal B is obtained by taking the difference between the electric signals of PD2 and PD4 that are 180 degrees out of phase. By counting the number of pulses of the electrical signal A or electrical signal B, it is possible to know how many pairs of the light transmitting portion 16b and the light reflecting portion 16a of the first scale 16 have moved. Therefore, by multiplying the counted number of pulses by the length of one set of the light reflecting portion 16a and the light transmitting portion 16b of the first scale 16 (see FIG. 5), the first scale 16 is applied to the first light detecting portion 20. The distance moved relatively can be obtained.

  Also in the second light receiving unit 28 of the second light detection unit 22, the light emitted from the second scale 18, particularly from the organic EL element 18 a, has a stripe pattern of the bright part 40 and the dark part 42 as shown in FIG. 5. Form. On the other hand, the PD array of the second light receiving unit 28 is also configured in the same manner as the first light receiving unit 26 with a plurality of sets of PDs including four PD elements PD1, PD2, PD3, and PD4. The Therefore, it is possible to detect the relative displacement in the Y-axis direction as described above with reference to FIGS.

  As described above, according to the present embodiment, the relative displacement in the X-axis direction can be detected by the striped first scale 16 extending in the Y-axis direction and the corresponding first light detection unit 20. Further, the relative displacement in the Y-axis direction can be detected by the striped second scale 18 extending in the X-axis direction and the corresponding second light detection unit 22. Therefore, according to the encoder 10, it is possible to detect displacement in the biaxial directions of the X axis and the Y axis.

  Further, in the encoder 10, the second scale 18 is configured to be capable of self-emission and configured to transmit light. Therefore, although the first scale 16 and the second scale 18 are overlapped and the second scale 18 extends between the first scale 16 and the first light detection unit 20, It is also possible to detect displacement in the Y-axis direction during displacement detection. Thus, since the first scale 16 and the second scale 18 can be overlapped, the encoder 10 is suitable for space saving.

  As mentioned above, although typical embodiment of this invention was described, this invention can be variously changed. Various substitutions and modifications may be made without departing from the spirit and scope of the present invention as defined by the claims of this application.

  In the above embodiment, the second scale 18 is configured to be able to transmit light from the first light emitting means, and is provided so as to extend between the first scale 16 and the first light detection unit 20. However, the first scale 16 may be provided so as to extend between the second scale 18 and the first light detection unit 20. In this case, the light from the second scale 18 becomes lattice-like light, passes through the light transmission part 16 b of the first scale 16, and reaches the second light detection part 22. Also in this case, the light of the pattern of the predetermined interval from the second scale can be substantially read by the second light detection unit 22, and therefore the relative displacement (for example, in the Y-axis direction using the second scale). Relative displacement).

  Moreover, in the said embodiment, the displacement which can be detected with an encoder was a relative displacement in the plane which has XY orthogonal axes as 2 axes | shafts. However, by setting at least one of the two axes as a curved axis (for example, around the origin), the encoder according to the present invention can detect two-axis displacement such as three-dimensional displacement or solid angle. That is, the first scale can be formed in a curved shape, and the second scale can be provided so as to overlap the first scale. In particular, since the organic EL can be manufactured with flexibility, the scale 12 can be made to have a scale adapted to the curved axis, in particular, the second scale 18.

  For example, in the above embodiment, the first light emitting unit 24 is provided in the first light detection unit 20. However, the first light emitting unit 24 may be provided separately from the first light detection unit 20. For example, in FIG. 2, the 1st light emission part 24 may be provided in the position which opposes the 1st photon detection part 20 on both sides of the scale 12. In this case, in the probe 1 of FIG. 1, the first light emitting unit 24 can be provided on the stylus holding member 5 side. Then, the light from the first light emitting part 24 can pass through the light transmitting part 16 b of the first scale 16 and reach the first light receiving means 26 of the first light detecting part 20.

  In the above embodiment, the first light emitting unit 24 emits red light, and the organic EL element 18a as the second light emitting unit emits blue light. However, the color or wavelength of light is not limited to these. The color or wavelength of the light of the first light emitting means and the second light emitting means may be selected so as not to interfere with each other.

DESCRIPTION OF SYMBOLS 1 Probe, 3 Housing, 5 Stylus holding member, 7a, 7b Spring member, 9 balls, 10 Encoder, 12 Scale, 14 Reading sensor, 16 1st scale, 16a Light reflection part, 16b Light transmission part, 18 2nd scale, 18a organic EL element (second light emitting means), 18b separator, 18u first electrode layer, 18v second electrode layer, 20 first light detecting part, 22 second light detecting part, 24 first light emitting part (first light emitting means) ), 26 First light receiving part (first light receiving means), 28 Second light receiving part (second light receiving means), 30 Electronic component

Claims (4)

A first scale in which light reflecting portions and light transmitting portions are alternately and continuously arranged;
A first light detection unit movable relative to the first scale, wherein the first scale is caused by light irradiation from a first light emitting unit for irradiating the first scale with light; A first light detection unit comprising: a first light receiving unit that receives the light reflected and returned by the light reflection unit or the light transmitted through the first scale, converts the light into an electrical signal, and outputs the electrical signal;
The second scale includes a second light emitting unit that is superposed on the first scale and is capable of emitting a striped pattern at a predetermined interval, wherein the striped pattern includes the light reflecting portion of the first scale and the second scale. A second scale extending in a direction intersecting with the light transmission part;
A second light detector that is movable relative to the second scale, and includes second light receiving means that receives light from the second scale, converts the light into an electrical signal, and outputs the electrical signal. An encoder comprising a detection unit. The second scale is
Configured to transmit light from the first light emitting means,
Extending between the first scale and the first light detector;
The encoder according to claim 1. The first scale extends between the second scale and the first light detection unit,
The encoder according to claim 1. The second light emitting means is configured to emit light of the striped pattern extending in a direction perpendicular to the light reflecting portion and the light transmitting portion of the first scale.
The encoder according to any one of claims 1 to 3.