JP2005208015A - Photoelectric type encoder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photoelectric type encoder capable of realizing a light receiving part with low joining capacity even with a narrowed pitch of optical grating of a scale. <P>SOLUTION: A light receiving part 7 comprises a p<SP>-</SP>-type semiconductor substrate 21 and a plurality of n<SP>+</SP>-type semiconductor areas 25 formed on a surface 23 of the substrate at intervals along the direction of a measuring axis X. The joining parts of the semiconductor substrate 21 with the semiconductor areas 24 become photodiodes (PD) 27. A second optical grating 35 is provided for every PD 27, and the dimension x1 of the second optical grating 35 in the measuring axial X direction is set larger than the dimension x2 of the n<SP>+</SP>-type semiconductor areas 25 in the measuring axial X direction. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a photoelectric encoder used for precision measurement.

  Conventionally, a photoelectric encoder (hereinafter also referred to as “encoder”) has been used for precise measurement of linear displacement and angular displacement. The encoder is mounted on a coordinate measuring machine or an image measuring machine. The encoder includes a light source, a scale including an optical grating, and a plurality of light receiving elements, and is disposed so as to be movable relative to the scale together with the light source, and each light receiving element has an index grating having a different phase on the light receiving surface. And a section.

  The operation of the photoelectric encoder will be briefly described. While moving the scale relative to the light source and the light receiving unit, light from the light source is irradiated onto the index grating through the optical grating of the scale. Thereby, a plurality of (for example, four) sinusoidal light-dark patterns having different phases are generated. This light / dark pattern of sinusoidal light becomes an optical signal. Light and dark patterns of light having different phases are received by light receiving elements corresponding to the respective phases, and a displacement amount such as a straight line is measured using an electric signal generated by photoelectric conversion.

  The four light light / dark patterns with different phases are the light / dark pattern of the A phase (0 degree), the light / dark pattern of the B phase (90 degrees) shifted by 90 degrees from the A phase, and the phase of 180 degrees from the A phase. The light and dark pattern of the shifted AA phase (180 degrees) and the light and dark pattern of the BB phase (270 degrees) shifted in phase by 270 degrees from the A phase. The reason why the bright and dark patterns of the A phase and the B phase are used is to determine the direction of relative movement of the light receiving unit depending on whether the A phase or the B phase is detected first. In addition, the AA phase and the BB phase obtained by inverting these in addition to the A phase and the B phase are used to remove the direct current component included in the light and dark pattern (optical signal) of the A phase and the B phase, and the optical signal. This is to ensure reliability and high-speed followability.

  If there are a number of light receiving elements corresponding to a plurality of light and dark patterns having different phases, measurement is possible in principle. Therefore, in the case of four light / dark patterns having different phases, it is sufficient if there are four light receiving elements. This first type of encoder is disclosed in Patent Document 1, for example.

  By the way, the light intensity may vary due to the light intensity distribution of the light source, the dirt on the scale surface, and the like. According to the above type, since the light / dark pattern of each phase is detected at one location, it is easily affected by variations in the amount of light. For example, when the intensity of the irradiated light is weaker at the place where the light receiving element for A phase is placed than at the place where the other light receiving elements are placed, the output of the A phase becomes weak and the measurement accuracy is lowered.

  Therefore, the light receiving elements for each phase are divided into a plurality of parts, and the light receiving elements are arranged in an array along the measurement axis direction of the encoder so that the light receiving elements for the same phase are periodically arranged. There is a second type of encoder (for example, Patent Document 2). In this type, the light receiving elements are arranged for A phase, B phase, AA phase, BB phase, A phase, B phase, and so on. Each light receiving element also functions as an index grating. According to this type, since the locations where the light and dark patterns of each phase are detected are dispersed over a wide range, the influence of the variation in the amount of light can be reduced (hereinafter referred to as “the averaging effect”). Accuracy is improved.

  To improve measurement accuracy, it is important to increase the averaging effect. However, simply trying to increase the averaging effect decreases the response speed of the encoder. This will be described in detail.

  The light receiving element is formed by joining an n-type semiconductor region and a p-type semiconductor region. When the capacity of this junction increases, the encoder cannot respond at high speed. Therefore, the increase in the junction capacity adversely affects the performance of the encoder. The junction capacitance of the light receiving element is correlated with the area of the light receiving surface and the length of the periphery (edge) of the light receiving surface. That is, the junction capacitance increases as the area and the circumference length increase, and the junction capacitance decreases as the area and the circumference length decrease.

  In the second type, even if the total area of the light receiving surface is the same as that of the first type, the number of light receiving elements is larger than that of the first type, so the total length of the periphery of the light receiving surface is increased. . Therefore, in the second type, the junction capacity of the light receiving unit is larger than that in the first type, and the response speed of the encoder is lowered.

As described above, in the conventional technique, if the averaging effect is increased, the junction capacity of the light receiving portion increases, and conversely, if the junction capacitance is decreased, the averaging effect decreases.
Pamphlet of International Publication No. 01/31292 (Specification, page 5, line 19 to page 6, line 7, Fig. 5) Japanese Patent Laid-Open No. 7-151565 (paragraph [0014], FIG. 4)

  In the case of the second type, when the optical grating of the scale is narrowed for more precise measurement, the light receiving elements must be narrowed correspondingly. For this reason, since the number of light receiving elements increases, when it is attempted to obtain the same light receiving area as in the prior art, the circumference of the light receiving surface increases and the junction capacitance of the light receiving portion increases. Therefore, when the pitch of the optical grating of the scale is narrowed, there arises a problem that the response speed of the encoder is lowered.

  The present invention has been made in view of such a problem, and an object of the present invention is to provide a photoelectric encoder that can realize a light-receiving portion having a low junction capacitance even when the optical grating of the scale is narrowed.

  A photoelectric encoder according to the present invention includes a light source, a scale including a first optical grating that generates a light / dark pattern of light along a measurement axis by light emitted from the light source, and a first semiconductor region of a first conductivity type. And a plurality of light receiving elements formed of a second semiconductor region of the second conductivity type formed on the surface of the region, and the light receiving elements for detecting a light / dark pattern of the same phase by the first optical grating are periodically positioned The light receiving elements for detecting the light and dark patterns of different phases are arranged along the measurement axis direction, and the light receiving unit is movable relative to the scale together with the light source. The light transmitting part and the light shielding part are arranged alternately along the measurement axis so as to correspond to the period of the bright and dark pattern by the first optical grating so as to be a light part, and the dimension in the measurement axis direction is Serial and second optical gratings provided the every light receiving element to be larger than the dimension of the measuring axis direction of the second semiconductor region, characterized in that it comprises a.

  According to the photoelectric encoder of the present invention, the second optical grating is provided for each light receiving element, and the dimension in the measurement axis direction of the second optical grating is set to the measurement axis of the second semiconductor region that is a component of the light receiving element. It is larger than the dimension in the direction. That is, since the dimension in the measurement axis direction of the second semiconductor region is smaller than the dimension in the measurement axis direction of the second optical grating, the area of the light receiving surface of each light receiving element can be reduced.

  In the photoelectric encoder according to the present invention, the second semiconductor region of one light receiving element may be non-divided. According to this, since the length of the periphery of the light receiving surface of each light receiving element can be shortened, it is possible to reduce the junction capacitance of the light receiving unit.

  In the photoelectric encoder according to the present invention, the second semiconductor region of one of the light receiving elements is divided into two parts, which are formed so as to face the light transmitting portions at both ends of the second optical grating. And so on. According to this, crosstalk in adjacent light receiving elements can be suppressed.

  The photoelectric encoder according to the present invention can also be as follows. (1) The second semiconductor region of one light receiving element is divided into a plurality of portions, and these are formed at intervals along the direction of the measurement axis. (2) The second semiconductor region of one of the light receiving elements is divided into a plurality of portions, and is formed at intervals along a direction orthogonal to the measurement axis.

  In the photoelectric encoder according to the present invention, the first encoder is formed in the first semiconductor region so as to be positioned between the second semiconductor regions of the adjacent light receiving elements and has a higher impurity concentration than the first semiconductor region. A third semiconductor region of a conductive type can be provided. According to this, crosstalk in adjacent light receiving elements can be suppressed.

  According to the photoelectric encoder of the present invention, since the area of the light receiving surface of each light receiving element can be reduced, a light receiving portion having a low junction capacitance can be realized even when the optical grating of the scale is narrowed.

  Hereinafter, first to fifth embodiments of a photoelectric encoder according to the present invention will be described with reference to the drawings. In addition, in the figure explaining 2nd-5th embodiment, about the same thing as what is shown with the code | symbol of already demonstrated embodiment, description is abbreviate | omitted by attaching | subjecting the same code | symbol.

[First Embodiment]
FIG. 1 is a diagram showing a schematic configuration of a photoelectric encoder 1 according to the first embodiment. This embodiment is mainly characterized by the structure of the light receiving portion, but the photoelectric encoder 1 will be described as a premise of this understanding. First, the configuration of the encoder 1 will be described. The encoder 1 includes a light emitting diode (LED) 3, a scale 5 that modulates light from the diode 3, and a light receiving unit 7 that receives light modulated by the scale 5.

  The light emitting diode 3 is an example of a light source, and the light 5 from the diode 3 is irradiated to the scale 5. The scale 5 includes a long transparent substrate 9 made of a transparent material such as glass, and a part thereof is shown in FIG. A first optical grating 11 is formed on the surface of the transparent substrate 9 opposite to the surface facing the light emitting diode 3 side. The first optical grating 11 is arranged such that a plurality of light shielding portions 13 are provided in a linear shape with a predetermined pitch, and each light shielding portion 13 extends in the depth direction of the drawing. The light shielding unit 13 is made of metal (for example, chromium).

  The light receiving unit 7 is arranged with a gap from the scale 5. The light receiving unit 7 is a semiconductor chip and is mounted on the circuit board 15. A plurality of photodiodes (hereinafter, “photodiodes” may be referred to as PDs) (not shown) are formed in the light receiving unit 7. The light receiving surfaces of these PDs face the first optical grating 11 side. PD is an example of a light receiving element. As the light receiving element, a phototransistor can be used instead of the PD. An IC chip 17 for calculation is mounted on the circuit board 15, and is displaced by the IC chip 17 on the basis of light / dark patterns (light signals) of sinusoidal light detected by a plurality of PDs of the light receiving unit 7. A quantity operation is performed.

  The circuit board 15 on which the light receiving unit 7 and the like are mounted is attached to the holder 19 together with the light emitting diode 3, and the holder 19 is movable in the measurement axis X direction which is the longitudinal direction of the scale 5. That is, the photoelectric encoder 1 measures the displacement amount by moving the holder 19 with respect to the fixed scale 5. Note that the present invention can also be applied to a type in which the light emitting diode 3 and the light receiving unit 7 are fixed and the scale 5 is moved to measure the amount of displacement. Therefore, the scale of the present invention is arranged to be relatively movable with respect to the light receiving unit and the light source.

  Next, the measurement operation of the photoelectric encoder 1 will be briefly described. When the light L from the light emitting diode 3 is applied to the first optical grating 11 of the scale 5, a light / dark pattern of light along the measurement axis X is generated by the first optical grating 11. Then, a change in light / dark pattern (sine wave-like optical signal) caused by moving the holder 19 along the measurement axis X is detected by each photodiode (PD) formed in the light receiving unit 7. Specifically, the light and dark pattern of phase A (0 degrees), the light and dark pattern of phase B (90 degrees) shifted by 90 degrees from phase A, and the phase AA (180 degrees) shifted by 180 degrees from phase A The bright and dark patterns of BB phase (270 degrees) whose phase is shifted by 270 degrees from the A phase are detected by the corresponding PDs.

  An electrical signal generated by the light / dark pattern of each phase is sent to the IC chip 17. In the IC chip 17, a predetermined amount of processing (DC component removal or the like) is performed on the A phase and the B phase, and then the displacement amount is calculated based on the processed A phase and B phase. The result is output to a display unit (not shown). The above is the operation of the photoelectric encoder 1.

Now, the main feature of the first embodiment is the light receiving unit 7, which will be described in detail. First, the structure of the light receiving unit 7 will be described with reference to FIGS. 2 is a cross-sectional view of a part of the light receiving unit 7, and FIG. 3 is a plan view of a part of the light receiving unit 7. The light receiving unit 7 includes a p ⁻ type semiconductor substrate 21 (an example of a first semiconductor region of a first conductivity type). An example of the semiconductor substrate 21 is a silicon substrate. N ⁺ type semiconductor regions 25 (an example of a second conductivity type second semiconductor region) are formed on the surface 23 of the semiconductor substrate 21 at a predetermined pitch. The semiconductor region 25 can also be referred to as an impurity region. In the semiconductor region 25, the direction perpendicular to the measurement axis X is the longitudinal direction.

A junction between the p ⁻ type semiconductor substrate 21 and the n ⁺ type semiconductor region 25 becomes a photodiode (PD) 27. The semiconductor region 25 of one PD 27 is not divided. Of the surface 23 of the semiconductor substrate 21, a region where the semiconductor region 25 is formed becomes a light receiving surface (incident surface of a light / dark pattern) 28 of the PD 27.

  The PD 27 for detecting the A-phase light / dark pattern, the PD 27 for detecting the B-phase light / dark pattern, the PD 27 for detecting the AA-phase light / dark pattern, and the PD 27 for detecting the BB-phase light / dark pattern are set as one set. A plurality of sets are arranged along the measurement axis X direction. Accordingly, the PDs 27 that detect the light and dark patterns having the same phase are periodically arranged.

  The surface 23 of the semiconductor substrate 21 is covered with an insulating film 29 such as a silicon oxide film so as to cover the semiconductor region 25. On the insulating film 29, a plurality of light shielding portions 31 are formed at intervals. The light-shielding part 31 should just have a property which does not permeate | transmit light, Therefore The material (for example, chromium, aluminum) and resin are mentioned for the material.

  A space between adjacent light shielding portions 31 is a light transmitting portion 33. The second optical grating (index grating) 35 is configured by alternately arranging the light transmitting portions 33 and the light shielding portions 31 along the measurement axis X so that both ends (both sides) are the light transmitting portions 33. The pitch of the light transmission parts 33 of the second optical grating 35 is equal to the pitch of the light transmission parts 14 of the first optical grating 11 (FIG. 1). Thereby, the second optical grating 35 corresponds to the period of the bright and dark pattern by the first optical grating 11. The second optical grating 35 is provided for each PD 27. The dimension x1 of the second optical grating 35 in the measurement axis X direction is larger than the dimension x2 of the semiconductor region 25 in the measurement axis X direction.

A protective film (not shown) such as a silicon oxide film or a silicon nitride film is formed on the semiconductor substrate 21 so as to cover the second optical grating 35. A common electrode (for example, Au electrode) 39 of each PD 27 is formed on the entire back surface 37 of the semiconductor substrate 21. When the encoder 1 is used, a negative voltage is applied to the common electrode 39 and a positive voltage is applied to the n ⁺ type semiconductor region 25.

  Here, the reason why the second embodiment is provided with the second optical grating 35 will be described. As described in the section “Problems to be Solved by the Invention”, if the pitch of the first optical grating 11 is narrowed for more precise measurement, the PD 27 needs to be narrowed correspondingly. The junction capacitance of the light receiving unit 7 increases.

  Therefore, the increase in the junction capacitance is suppressed by increasing the dimension x2 of the PD 27 in the measurement axis X direction to reduce the number of PDs 27. Since the dimension x2 of the PD 27 is increased, the second optical grating 35 is disposed. As described above, in the first embodiment, by using the PD 27 and the second optical grating 35 arranged in an array, it is possible to cope with the narrow pitch of the first optical grating 11 and to reduce the junction capacitance of the light receiving unit 7. ing.

  The main effects of the photoelectric encoder 1 according to the first embodiment will be described in comparison with a comparative example. FIG. 4 is a sectional view of a part of the light receiving unit 7 according to the comparative example, and corresponds to FIG. 4 differs from FIG. 2 in the dimension x2 of the semiconductor region 25. FIG. In the comparative example, the dimension x2 of the semiconductor region 25 is made larger than the dimension x1 of the second optical grating 35 in order to reliably receive the light / dark pattern of the light that has passed through the second optical grating 35.

However, electrons generated by light incident near the light receiving surface 28 flow into the semiconductor region 25 with a high probability. FIG. 5 is an enlarged cross-sectional view of a part of the light receiving unit 7 of the first embodiment showing this state. The light L passes through the light transmitting portion 33 and is incident on the semiconductor substrate 21 from the vicinity of the light receiving surface 28, thereby generating a pair of electrons and holes in the semiconductor substrate 21. The electrons diffuse in the semiconductor substrate 21 while being attenuated and flow into the n ⁺ -type semiconductor region 25. According to experiments, it has been confirmed that electrons generated at a location 400 μm away from the semiconductor region 25 also flow into the semiconductor region 25.

  On the other hand, the pitch of the light shielding portions 31 of the second optical grating 35 is, for example, 8 to 10 μm. Therefore, as shown in FIG. 2, even if the dimension x2 of the semiconductor region 25 is smaller than the dimension x1 of the second optical grating 35, it is generated by the light incident on the semiconductor substrate 21 through the light transmitting portion 33 of the second optical grating 35. It is possible for electrons to flow through the semiconductor region 25 of the PD 27 corresponding to the second optical grating 35. That is, even if the dimension x2 of the semiconductor region 25 is smaller than the dimension x1 of the second optical grating 35, it can function sufficiently as the PD 27.

As described above, according to the first embodiment, the dimension x2 of the n ⁺ type semiconductor region 25 is smaller than the dimension x1 of the second optical grating 35 (in other words, the dimension x1 is larger than the dimension x2). Therefore, the dimension of the semiconductor region 25 in the measurement axis X direction can be reduced. Thereby, since the area of the light receiving surface 28 of each PD 27 can be reduced, the junction capacitance of the light receiving unit 7 can be reduced even if the first optical grating 11 of the scale 5 has a narrow pitch.

In the first embodiment, the n ⁺ type semiconductor region 25 of each PD 27 is not divided. For this reason, since the length of the periphery of the light receiving surface 28 of each PD 27 can be shortened, the junction capacitance of the light receiving unit 7 can also be reduced from this point.

[Second Embodiment]
The second embodiment will be described focusing on the differences from the first embodiment. FIG. 6 is a cross-sectional view of a part of the light receiving unit 7 provided in the photoelectric encoder according to the second embodiment, and corresponds to FIG. The light receiving unit 7 of the second embodiment includes a p ⁺ type semiconductor region (an example of a first conductivity type third semiconductor region) 41 having a p type impurity concentration higher than that of the p ⁻ type semiconductor substrate 21. This region 41 is also referred to as an impurity region, and is formed in the semiconductor substrate 21 so as to be positioned between the n ⁺ type semiconductor regions 25 of the adjacent PDs 27. The p ⁺ type semiconductor region 41 is set to the same potential as the common electrode 39.

  The effect of the semiconductor region 41 will be described with reference to FIG. FIG. 7 is an enlarged cross-sectional view of a part of FIG. 6 and corresponds to FIG. As described in the first embodiment, electrons generated by light incident in the vicinity of the light receiving surface 28 of the PD 27-1 flow into the semiconductor region 25 of the PD 27-1 with a high probability. However, it may flow to the semiconductor region 25 of the PD 27-2. In this case, crosstalk occurs, which causes a reduction in measurement accuracy.

In the second embodiment, since the p ⁺ -type semiconductor region 41 is disposed between the n ⁺ -type semiconductor regions 25 of the adjacent PDs 27-1 and 27-2, electrons that cause crosstalk are transferred to the region 41. Can flow in. Therefore, crosstalk can be suppressed.

[Third Embodiment]
FIG. 8 is a cross-sectional view of a part of the light receiving unit 7 provided in the photoelectric encoder according to the third embodiment, and corresponds to FIG. Unlike the first embodiment, the third embodiment divides the n ⁺ -type semiconductor region 25 of one PD 27 into two divided regions 25a and 25b. The divided regions 25 a and 25 b are formed in the semiconductor substrate 21 so as to face the light transmitting portions 33 at both ends of the second optical grating 35.

  FIG. 9 is an enlarged cross-sectional view of a part of FIG. 8, and corresponds to FIG. A pair of electrons and holes is generated by entering the semiconductor substrate 21 through the light transmitting portion 33 at the center of the second optical grating 35. Since there are the semiconductor regions 25 on both sides of the electron generation location, it is possible to prevent electrons from flowing into the semiconductor region 25 of the adjacent PD 27. Therefore, according to the third embodiment, crosstalk can be suppressed.

  As described above, the junction capacitance increases when the area of the photodiode and the pattern edge length are large. Therefore, the total value of the junction capacitance by the divided region 25a and the junction capacitance by the divided region 25b is smaller than the junction capacitance of the photodiode whose dimension in the measurement axis X direction is equal to the dimension x1 of the second optical grating 35. If the dimensions x2a and x2b are set, the junction capacitance of the light receiving unit 7 can be reduced. Here, the dimension x2a is a dimension in the measurement axis X direction of the divided area 25a, and the dimension x2b is a dimension in the measurement axis X direction of the divided area 25b.

[Fourth Embodiment]
The photoelectric encoder according to the fourth embodiment will be described focusing on differences from the first embodiment. FIG. 10 is a plan view of a part of the light receiving unit 7 provided in the photoelectric encoder according to the fourth embodiment, and corresponds to FIG. 3 of the first embodiment. In the fourth embodiment, the n ⁺ type semiconductor region 25 of one PD is divided into two divided regions 25a and 25b, and the divided regions 25a and 25b are spaced along a direction orthogonal to the measurement axis X. Is formed.

  According to the fourth embodiment, as described in the first embodiment, since the area of the light receiving surface of each PD can be reduced, the junction capacitance of the light receiving unit 7 can be reduced.

  Further, since the gap G between the divided regions 25a and 25b is larger than the dimension x2 in the measurement axis X direction, the length of the periphery of the light receiving surface of each PD can be reduced. Also from this point, the junction capacitance of the light receiving unit 7 can be reduced.

[Fifth Embodiment]
FIG. 11 is a cross-sectional view of one PD formed in the light receiving portion of the photoelectric encoder according to the fifth embodiment. In the embodiments described so far, the n ⁺ -type semiconductor region 25 is not divided or divided into two, but the semiconductor region 25 may be divided into three or more. In the fifth embodiment, the semiconductor region 25 is divided into three divided regions 25a, 25b, and 25c. Even if it is such a structure, the effect similar to 1st Embodiment can be acquired.

It is a figure which shows schematic structure of the photoelectric encoder which concerns on 1st Embodiment. It is sectional drawing of a part of light-receiving part of FIG. FIG. 2 is a plan view of a part of the light receiving unit in FIG. 1. It is sectional drawing of a part of light-receiving part which concerns on a comparative example. FIG. 3 is an enlarged cross-sectional view of a part of the light receiving unit in FIG. 2. It is sectional drawing of a part of light-receiving part with which the photoelectric encoder which concerns on 2nd Embodiment is equipped. It is sectional drawing to which a part of FIG. 6 was expanded. It is sectional drawing of a part of light-receiving part with which the photoelectric encoder which concerns on 3rd Embodiment is equipped. It is sectional drawing to which a part of FIG. 8 was expanded. It is a top view of a part of light-receiving part with which a photoelectric encoder concerning a 4th embodiment is equipped. It is sectional drawing of one PD of the photoelectric encoder which concerns on 5th Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Photoelectric encoder, 3 ... Light emitting diode, 5 ... Scale, 7 ... Light-receiving part, 9 ... Transparent substrate, 11 ... 1st optical grating, 13 ... Light-shielding part 14... Translucent part, 15... Circuit board, 17... IC chip, 19... Holder, 21... P ^- type semiconductor substrate (an example of the first semiconductor region), 23. ..Surface of semiconductor substrate, 25... N ⁺ type semiconductor region (an example of a second semiconductor region), 25a, 25b, 25c... Divided region, 27, 27-1, 27-2. Diode (PD), 28 ... light receiving surface, 29 ... insulating film, 31 ... light shielding part, 33 ... light transmitting part, 35 ... second optical grating, 37 ... semiconductor substrate backside, (an example of the third semiconductor region) 39 ... common electrode, 41 ... ^{p +} -type semiconductor region, x1 ... second Measurement lattice X in the measurement axis X direction, x2... Measurement in the measurement axis X direction of the semiconductor region 25, x2a... Measurement in the measurement axis X direction in the divided region 25a, x2b. Dimension in the axis X direction, G... Distance between divided area 25a and divided area 25b

Claims (6)

A light source;
A scale including a first optical grating that generates a light-dark pattern of light along a measurement axis by light emitted from the light source;
A plurality of light receiving elements each including a first semiconductor region of the first conductivity type and a second semiconductor region of the second conductivity type formed on the surface of this region are detected, and a light and dark pattern having the same phase is detected by the first optical grating. The light receiving elements that detect the light and dark patterns of different phases are arranged along the measurement axis direction so that the light receiving elements are periodically positioned, and are moved relative to the scale together with the light source. Possible light receivers,
The light-transmitting portions and the light-shielding portions are arranged alternately along the measurement axis so as to correspond to the period of the bright and dark pattern by the first optical grating so that both ends become light-transmitting portions, and the dimensions in the measurement axis direction A second optical grating provided for each of the light receiving elements so as to be larger than the dimension of the second semiconductor region in the measurement axis direction.
A photoelectric encoder characterized by that. The second semiconductor region of one light receiving element is non-divided;
The photoelectric encoder according to claim 1. The second semiconductor region of one of the light receiving elements is divided into two, and these are formed so as to face the light transmitting portions at both ends of the second optical grating,
The photoelectric encoder according to claim 1. The second semiconductor region of one of the light receiving elements is divided into a plurality of parts, and these are formed at intervals along the direction of the measurement axis.
The photoelectric encoder according to claim 1. The second semiconductor region of one of the light receiving elements is divided into a plurality of portions, and is formed at intervals along a direction orthogonal to the measurement axis.
The photoelectric encoder according to claim 1. A third semiconductor region of a first conductivity type formed in the first semiconductor region so as to be positioned between the second semiconductor regions of the adjacent light receiving elements and having a higher impurity concentration than the first semiconductor region; ,
The photoelectric encoder according to any one of claims 1 to 5, wherein:

Images