CN204188180U - Motor, the servo-drive system of scrambler, band scrambler - Google Patents

Abstract

The utility model provides an encoder, a motor with an encoder, and a servo system, which can realize high resolution of the encoder. The encoder (100) has: a plurality of slot tracks (SI1, SI2) each having a plurality of slots arranged in a measuring direction; a light source (121) configured to provide Emitting light; a light-receiving array (PI2) configured to receive light reflected by a slot track (SI2) having an incremental pattern; and a light-receiving array (PI1) configured to receive light reflected by a slot track (SI2) having a pitch ratio The light reflected by the slot track (SI1) of the incremental pattern is long, and the length (WPI1) of the light receiving array (PI1) in the width direction (R) is longer than the length (WPI2) of the light receiving array (PI2) )short.

Description

Encoders, motors with encoders, servo systems

technical field

The disclosed embodiments relate to encoders, motors with encoders, servo systems.

Background technique

Patent Document 1 describes an absolute encoder including: a rotating plate on which a plurality of optical patterns capable of outputting a difference of two or more cycles when one rotation is made a periodic signal; and an optical detection unit including a plurality of photosensors that receive light transmitted through each optical pattern.

prior art literature

Patent Document 1: Japanese Patent Laid-Open No. 2009-294073

In the prior art described above, in order to achieve higher resolution of the encoder, it is desired to optimize the arrangement of the optical sensors in the optical detection unit, but this has not been particularly considered.

Utility model content

The present invention has been made in view of such a problem, and an object thereof is to provide an encoder, a motor with an encoder, and a servo system capable of achieving high resolution.

In order to solve the above-mentioned problems, according to a viewpoint of the utility model, an encoder is applied, which has: a plurality of slot tracks, which respectively have a plurality of slots arranged along the measurement direction; The first light-receiving array is configured to receive the light reflected or transmitted by the slot track having an incremental pattern; The light reflected by the slot track of the incremental pattern with long measurement pattern, and the size of the second light-receiving array in the width direction perpendicular to the measurement direction is smaller than that of the first light-receiving array.

In addition, in order to solve the above-mentioned problems, according to another aspect of the present invention, there is provided a motor with an encoder, which includes: a linear motor in which the movable body moves relative to the fixed body; or a rotary motor in which the rotor rotates relative to the stator. a motor; and the aforementioned encoder configured to detect at least one of a position and a speed of the movable body or the rotor.

In addition, in order to solve the above-mentioned problems, according to another viewpoint of the present invention, a servo system is provided, which includes: a linear motor in which the movable body moves relative to the fixed body, or a rotary motor in which the rotor rotates relative to the stator; an encoder configured to detect at least one of the position and speed of the movable body or the rotor; and a control device configured to control the linear motor or the rotary motor based on a detection result of the encoder. type motor.

Utility Model Effect

According to the encoder and the like of the present invention, high resolution can be achieved.

Description of drawings

FIG. 1 is an explanatory diagram for explaining a servo system according to one embodiment.

FIG. 2 is an explanatory diagram for explaining the encoder of this embodiment.

FIG. 3 is an explanatory diagram for explaining the disk of this embodiment.

FIG. 4 is an explanatory diagram for explaining the slot track of the embodiment.

FIG. 5 is an explanatory diagram for explaining the optical module and the light receiving array of the embodiment.

FIG. 6 is an explanatory diagram for explaining a position data generation unit according to the embodiment.

FIG. 7 is an explanatory diagram for explaining diffuse reflection due to irregularities on the surface of the disc according to this embodiment.

FIG. 8 is an explanatory diagram for explaining the directionality of diffuse reflection components caused by convex portions.

FIG. 9 is an explanatory diagram for explaining the intensity distribution of the diffuse reflection component viewed from the positive direction of the X-axis.

FIG. 10 is an explanatory diagram for explaining the intensity distribution of the diffuse reflection component viewed from the positive Z-axis direction.

FIG. 11 is an explanatory diagram for explaining an optical module and a light-receiving array of a first modified example.

FIG. 12 is an explanatory diagram for explaining an optical module and a light-receiving array of a second modified example.

FIG. 13 is an explanatory diagram for explaining an optical module and a light-receiving array of a third modified example.

Label description

100: encoder;

120: optical module;

121: light source;

C: measuring direction;

CT: control device;

ci1: center position;

ci2: center position;

gPA1: shortest distance;

gPA2: shortest distance;

gPI: shortest distance;

gPI1: shortest distance;

gPI2: shortest distance;

lpi2: length;

M: motor;

PA: light receiving array;

PA1, PA2: light receiving array;

PI1: light receiving array;

PI2: light receiving array;

S: servo system;

SA1: slot track;

SA2: slot track;

SI1: slot track;

SI2: slot track;

SM: Servo motor.

Detailed ways

Hereinafter, one embodiment will be described with reference to the drawings.

In addition, the encoders of the embodiments described below can be applied to various types of encoders such as rotary (rotary type) and linear (linear type). In the following, for easy understanding of the encoder, a rotary encoder is taken as an example for description. When applied to other types of encoders, it can be realized by changing the object to be measured from a rotary disk to a linear linear scale, etc., and thus detailed description is omitted.

＜1.Servo system＞

First, the configuration of the servo system according to the present embodiment will be described with reference to FIG. 1 . As shown in FIG. 1 , the servo system S has a servo motor SM and a control device CT. The servo motor SM has an encoder 100 and a motor M.

The motor M is an example of a power generation source that does not include the encoder 100 . The motor M is a rotary motor in which a rotor (not shown) rotates with respect to a stator (not shown), and outputs a rotational force by rotating a shaft SH fixed to the rotor around an axis AX.

In addition, although the motor M alone may be referred to as a servo motor, in this embodiment, the structure including the encoder 100 is referred to as a servo motor SM. That is, the servo motor SM corresponds to an example of a motor with an encoder. Hereinafter, for convenience of explanation, a case will be described where the motor with an encoder is a servomotor controlled so as to follow target values such as position and speed, but it is not necessarily limited to a servomotor. Motors with encoders include motors used in other than servo systems as long as an encoder is additionally provided, for example, when they are used only for displaying the output of the encoder.

In addition, the motor M is not particularly limited as long as the encoder 100 can detect, for example, position data. In addition, the motor M is not limited to an electric motor using electric power as a power source, and may be a motor using another power source such as a hydraulic motor, an air motor, or a steam motor, for example. However, for convenience of description, the case where the motor M is an electric motor will be described below.

The encoder 100 is connected to the side of the motor M opposite to the rotational force output side of the shaft SH. However, it is not necessarily limited to the opposite side, and the encoder 100 may be connected to the rotational force output side of the shaft SH. In addition, the encoder 100 may be connected via other mechanisms such as a speed reducer and a rotation direction converter, for example. The encoder 100 detects the position (also referred to as rotation angle) of the motor M by detecting the position of the shaft SH (rotor), and outputs position data indicating the position.

The encoder 100 can also detect the speed of the motor M (also referred to as rotational speed, angular velocity, etc.) and the acceleration of the motor M (also referred to as rotational acceleration, angular acceleration) on the basis of or instead of the position of the motor M. etc.) at least one of. In this case, the speed and acceleration of the motor M can be determined by, for example, performing first-order or second-order differentiation of the position with time, or counting detection signals (for example, incremental signals described later) at a predetermined time. detection. For the convenience of description, the following description will be made by taking the physical quantity detected by the encoder 100 as the position.

The control device CT acquires the position data output from the encoder 100, and controls the rotation of the motor M based on the position data. Therefore, in the present embodiment using an electric motor as the motor M, the control device CT controls the rotation of the motor M by controlling the current or voltage applied to the motor M based on the position data. In addition, the control device CT may obtain a high-level control signal from a high-level control device (not shown), and may control the motor M so that the shaft SH of the motor M outputs a rotational force capable of realizing a position indicated by the high-level control signal. . In addition, when another power source such as a hydraulic type, an air type, or a steam type is used for the motor M, the control device CT can control the rotation of the motor M by controlling the supply of the power source.

＜2. Encoder＞

Next, the encoder 100 of this embodiment will be described. As shown in FIG. 2 , the encoder 100 has a disk 110 , an optical module 120 , and a position data generation unit 130 .

Here, for the convenience of describing the structure of the encoder 100, directions such as up and down are defined as follows and used as appropriate. In FIG. 2 , the direction in which the disk 110 faces the optical module 120 , that is, the positive direction of the Z-axis is defined as "up", and the negative direction of the Z-axis is defined as "down". However, this direction changes according to the installation form of the encoder 100 , and does not limit the positional relationship of the respective components of the encoder 100 .

(2-1. plate)

The disc 110 is formed in a disc shape as shown in FIG. 3 , and the disc center O is arranged so as to substantially coincide with the axis AX. The disk 110 is connected to the shaft SH of the motor M, and is rotated by the rotation of the shaft SH. In addition, in the present embodiment, as an example of the object to be measured for measuring the rotation of the motor M, the disc-shaped disk 110 is described as an example, but other members such as the end surface of the shaft SH may also be used as the object to be measured. object. Furthermore, in the example shown in FIG. 2 , the disk 110 is directly connected to the shaft SH, but it may be connected via a connecting member such as a hub.

As shown in FIG. 3, the disc 110 has a plurality of slit tracks SA1, SA2, SI1, SI2. The disk 110 rotates together with the drive of the motor M, but the optical module 120 is fixedly arranged to face a part of the disk 110 . Therefore, the slot tracks SA1 , SA2 , SI1 , SI2 and the optical module 120 are aligned with each other in the measurement direction (the direction of the arrow C shown in FIG. 3 . Hereinafter, it is appropriately described as "measurement direction C") as the motor M is driven. relatively mobile.

Here, the “measurement direction” refers to the measurement direction when the optical module 120 performs optical measurement of each groove track formed on the disc 110 . As in this embodiment, in a rotary encoder in which the object to be measured is the disk 110, the measurement direction coincides with the circumferential direction centered on the central axis of the disk 110. In a linear encoder that moves relative to a fixed body, the measurement direction is the direction along the linear scale. In addition, the "central axis" refers to the rotational axis of the disk 110, and coincides with the axis AX of the shaft SH when the disk 110 is coaxially connected to the shaft SH.

(2-2. Optical detection mechanism)

The optical detection mechanism has slot tracks SA1 , SA2 , SI1 , SI2 and an optical module 120 . Each slot track is formed as a track arranged in an annular shape around the disk center O on the upper surface of the disk 110 . Each slot track has a plurality of reflective slots arranged along the measurement direction C over the entire circumference of the track (hatched portion in FIG. 4 ). Each reflective slot reflects the light irradiated from the light source 121 .

(2-2-1. plate)

The disc 110 is formed of, for example, a light-reflecting material such as metal. In addition, a material with low reflectance (for example, chromium oxide, etc.) is placed on the portion of the surface of the disk 110 that does not reflect light by coating or the like, thereby forming reflective grooves on the portion that is not placed. In addition, reflective grooves may be formed by roughening portions that do not reflect light by sputtering or the like to reduce reflectivity.

In addition, the material, manufacturing method, etc. of the disc 110 are not particularly limited. For example, the disc 110 may be formed of a light-transmitting material such as glass or transparent resin. In this case, reflective grooves can be formed by disposing a light-reflecting material (for example, aluminum, etc.) on the surface of the disc 110 by vapor deposition or the like.

Four slot tracks are arranged side by side in the width direction (the direction of the arrow R shown in FIG. 3 . Hereinafter, it will be referred to as “the width direction R” as appropriate) on the upper surface of the disk 110 . The "width direction" refers to the radial direction of the disk 110, that is, the direction substantially perpendicular to the measurement direction C, and the length of each slot track along the width direction R corresponds to the width of each slot track. The four slot tracks are concentrically arranged in the order of SA1 , SI1 , SI2 , and SA2 from the inner side toward the outer side in the width direction R. In order to describe each slot track in more detail, FIG. 4 shows a partially enlarged view of the vicinity of the region of the disc 110 facing the optical module 120 .

As shown in FIG. 4 , the plurality of reflection grooves included in the groove tracks SA1 and SA2 are arranged on the entire circumference of the disk 110 so as to have an absolute pattern in the measurement direction C. As shown in FIG.

The term "absolute pattern" refers to a pattern in which the positions, ratios, etc. of the reflective slots within the angle facing the light receiving array of the optical module 120 described later are uniquely determined within one rotation of the disk 110 . That is to say, for example, in the case of the example of the absolute pattern shown in FIG. The combination of patterns can uniquely represent the absolute position of the angular position. In addition, "absolute position" refers to an angular position with respect to the origin within one rotation of the disk 110 . The origin is set at an appropriate angular position within one rotation of the disk 110, and an absolute pattern is formed with this origin as a reference.

In addition, according to an example of the pattern, it is possible to generate a pattern in which the absolute position of the motor M is expressed one-dimensionally by bits of the number of light-receiving elements of the light-receiving array. However, the absolute pattern is not limited to this example. For example, it may be a pattern multi-dimensionally expressed by bits of the number of light-receiving elements. In addition, other than a predetermined bit pattern, a pattern in which an absolute position is uniquely changed by a physical quantity such as a light quantity received by a light receiving element or a phase, or a pattern obtained by modulating a symbol series of an absolute pattern may be used. Various patterns are also possible.

In addition, in the present embodiment, the same absolute pattern is offset in the measurement direction C by, for example, 1/2 the length of 1 bit to form two slot tracks SA1 and SA2. This offset amount corresponds to, for example, half the pitch P1 of the reflection slots of the slot track SI1 . Assuming that the slot tracks SA1 and SA2 are not configured to be offset in this way, the following possibility exists. That is, when the absolute position is represented by a one-dimensional absolute pattern as in the present embodiment, the position realized when the light receiving elements of the light receiving arrays PA1 and PA2 are positioned opposite to the vicinity of the ends of the reflective slots In the region of the transition point (変わり目) of the original pattern, the detection accuracy of the absolute position may decrease. In this embodiment, since the slot tracks SA1 and SA2 are offset, for example, when the absolute position based on the slot track SA1 corresponds to a transition point of the bit pattern, the detection from the slot track SA2 is used. The signal calculates the absolute position, or vice versa, whereby the detection accuracy of the absolute position can be improved. In addition, in the case of such a structure, it is necessary to make the light receiving amounts of the two light receiving arrays PA1 and PA2 uniform, but in this embodiment, since the two light receiving arrays PA1 and PA2 are arranged at approximately equal distances from the light source 121 position, so the above structure can be realized.

In addition, instead of offsetting the absolute patterns of the slot tracks SA1 and SA2, for example, instead of offsetting the absolute patterns, the light-receiving arrays PA1 and PA2 respectively corresponding to the slot tracks SA1 and SA2 may be measured. Bias in direction C.

On the other hand, the plurality of reflection slots included in the slot tracks SI1 and SI2 are arranged in an incremental pattern in the measurement direction C over the entire circumference of the disk 110 .

As shown in FIG. 4 , the "incremental pattern" refers to a pattern that is regularly repeated at a predetermined pitch. Here, the "pitch" refers to the arrangement interval of the reflective slots of the slot tracks SI1 and SI2 having an incremental pattern. As shown in FIG. 4, the pitch of the slot track SI1 is P1, and the pitch of the slot track SI2 is P2. The incremental pattern is different from the absolute pattern that expresses the absolute position by using the presence or absence of detection of multiple light-receiving elements as bits. Each pitch or pitch is represented by the sum of the detection signals of at least one or more light-receiving elements. The position of the motor M within. Therefore, the incremental pattern does not represent the absolute position of the motor M, but it can represent the position with very high precision compared with the absolute pattern.

In this embodiment, the pitch P1 of the slot track SI1 is set to be longer than the pitch P2 of the slot track SI2. In this embodiment, each pitch is set so that P1=2×P2. That is, the number of reflection slots of the slot track SI2 is twice the number of reflection slots of the slot track SI1. However, the relationship of the slot pitch is not limited to this example, and various values such as 3 times, 4 times, and 5 times can be taken, for example.

In addition, in the present embodiment, the minimum length of the reflection slots of the slot tracks SA1 and SA2 in the measurement direction C matches the pitch P1 of the reflection slots of the slot track SI1 . As a result, the resolution of the absolute signal based on the slot tracks SA1 , SA2 corresponds to the number of reflection slots of the slot track SI1 . However, the minimum length is not limited to this example, and the number of reflection slots of the slot track SI1 is preferably set to be equal to or greater than the resolution of the absolute signal.

(2-2-2. Optical module)

As shown in FIGS. 2 and 5 , the optical module 120 is formed as a single substrate BA parallel to the disk 110 . Accordingly, the thickness of the encoder 100 can be reduced, and the optical module 120 can be easily manufactured. Therefore, as the disk 110 rotates, the optical module 120 relatively moves in the measurement direction C with respect to the slot tracks SA1 , SA2 , SI1 , and SI2 . In addition, the optical module 120 is not necessarily configured as a single substrate BA, and each structure may be configured as a plurality of substrates. In this case, these substrates may be collectively arranged. In addition, the optical module 120 does not need to be in the form of a substrate.

As shown in FIGS. 2 and 5 , the optical module 120 has a light source 121 and a plurality of light-receiving arrays PA1 , PA2 , PI1 , and PI2 on the surface of the substrate BA facing the disc 110 .

As shown in FIG. 3 , the light source 121 is disposed at a position facing between the slot track SI1 and the slot track SI2 . Furthermore, the light source 121 emits light to the opposing portions of the four slot tracks SA1 , SA2 , SI1 , and SI2 passing through the opposing positions of the optical module 120 .

The light source 121 is not particularly limited as long as it is capable of irradiating light to the irradiation area, for example, an LED (Light Emitting Diode, light emitting diode) can be used. The light source 121 is particularly configured as a point light source without an optical lens or the like, and emits diffused light from a light emitting unit. In addition, in the case of a "point light source", it does not have to be strictly a point, and light may be emitted from a limited emission surface as long as it is considered to emit diffused light from a substantially point-like position in terms of design or operating principle. In addition, "diffused light" is not limited to light emitted from a point light source in all directions, but includes light diffused and emitted in a limited fixed direction. That is, the diffused light referred to here includes light as long as it is more diffuse than parallel light. By using the point light sources in this way, the light source 121 can irradiate the four slot tracks SA1 , SA2 , SI1 , and SI2 passing through the opposing positions with substantially equal light. In addition, since light collection and diffusion by optical elements are not performed, errors due to optical elements are less likely to occur, and linearity of light traveling to the slot track can be improved.

A plurality of light receiving arrays PA1, PA2, PI1, and PI2 are arranged around the light source 121, and have a plurality of light receiving elements (dotted shaded parts in FIG. 5) that respectively receive light reflected by the reflection slots of the corresponding slot tracks. The plurality of light receiving elements are arranged along the measurement direction C as shown in FIG. 5 .

In addition, the light emitted from the light source 121 is diffused light. Therefore, the image of the slot track projected onto the optical module 120 is enlarged at a predetermined magnification factor ε corresponding to the optical path length. That is to say, as shown in FIG. 4 and FIG. 5, if the respective lengths of the slot tracks SA1, SA2, SI1, and SI2 in the width direction R are WSA1, WSA2, WSI1, and WSI2, and their reflected light is projected onto the optical The length of the shape of the module 120 in the width direction R is WPA1, WPA2, WPI1, WPI2, and WPA1, WPA2, WPI1, WPI2 are ε times the length of WSA1, WSA2, WSI1, WSI2. In addition, in this embodiment, as shown in FIG. 5 , an example is shown in which the length of the light receiving elements of each light receiving array in the width direction R is set to be approximately equal to the shape of each slot projected on the optical module 120 . However, the length of the light receiving element in the width direction R is not necessarily limited to this example. For example, in the light receiving arrays PA1 and PA2, the lengths of the respective light receiving elements in the width direction R may be different.

Similarly, the measurement direction C on the optical block 120 is also a shape in which the measurement direction C on the disk 110 is projected onto the optical block 120 , that is, a shape affected by the magnification ε. For easy understanding, the measurement direction C at the position of the light source 121 as shown in FIG. 2 will be taken as an example for specific description. The measurement direction C of the disc 110 is circular with the axis AX as the center. In contrast, the center of the measurement direction C projected onto the optical module 120 is located at a distance εL away from the optical center Op, which is the in-plane position of the disk 110 where the light source 121 is arranged. The distance εL is a distance obtained by enlarging the distance L between the axis AX and the optical center Op by the magnification factor ε. In FIG. 2 , this position is conceptually shown as the measurement center Os. Therefore, the measurement direction C of the optical module 120 is located on a line centered on the measurement center Os and having the distance εL as a radius. The center AX direction is away from the distance εL.

In FIGS. 4 and 5 , the corresponding relationship between the measurement directions C of the disk 110 and the optical module 120 is shown by arc-shaped lines Lcd and Lcp. The line Lcd shown in FIG. 4 represents the line along the measurement direction C on the disk 110, on the other hand, the line Lcp shown in FIG. 5 represents the line along the measurement direction C on the substrate BA (the line Lcd is projected onto the optical line on module 120).

As shown in FIG. 2 , when G is the distance between optical module 120 and disk 110 and Δd is the protrusion amount of light source 121 from substrate BA, magnification ε is expressed by the following (Equation 1).

ε=(2G-Δd)/(G-Δd)...(Formula 1)

As each light receiving element, for example, a photodiode can be used. However, it is not limited to a photodiode, and is not particularly limited as long as it can receive light emitted from the light source 121 and convert it into an electrical signal.

The light receiving array of this embodiment is arranged corresponding to four slot tracks SA1, SA2, SI1, and SI2. The light receiving array PA1 is configured to receive light reflected by the slot track SA1 , and the light receiving array PA2 is configured to receive light reflected by the slot track SA2 . Furthermore, the light receiving array PI1 is configured to receive the light reflected by the slot track SI1, and the light receiving array PI2 is configured to receive the light reflected by the slot track SI2.

The light source 121, the light receiving arrays PA1, PA2, and the light receiving arrays PI1, PI2 are arranged in the positional relationship shown in FIG. 5 . The light receiving arrays PA1 and PA2 corresponding to the absolute pattern are disposed so as to sandwich the light source 121 in the width direction R therebetween. In this example, the light receiving array PA1 is arranged on the inner peripheral side, and the light receiving array PA2 is arranged on the outer peripheral side. In this embodiment, the distances between the light receiving arrays PA1 and PA2 and the light source 121 are substantially equal. That is, light receiving array PA1, PA2 is arrange|positioned so that the light source 121 may be sandwiched between these in the width direction R, and it is substantially symmetrical. In addition, the term "substantially symmetrical" here means that the light-receiving arrays PA1 and PA2 are formed substantially symmetrically with respect to a line passing through the light source 121 in the measurement direction C, except for a curved shape centered on the measurement center Os. The line-symmetric shape of the axis. And the some light receiving element which light receiving array PA1, PA2 has is arrange|positioned at constant pitch along measurement direction C (line Lcp), respectively. In the light-receiving arrays PA1 and PA2, the reflected light from the slot tracks SA1 and SA2 is respectively received, and an absolute signal having a bit pattern of the number of light-receiving elements is generated. In addition, light receiving arrays PA1 and PA2 correspond to an example of the 3rd light receiving array.

Light receiving array PI1 and light receiving array PI2 corresponding to the incremental pattern are arranged between two light receiving arrays PA1 and PA2 in the width direction R. In this example, the light receiving array PI1 is arranged between the light receiving array PA1 and the light source 121 , and the light receiving array PI2 is arranged between the light receiving array PA2 and the light source 121 . Light receiving array PI1 is arrange|positioned at the center axis side rather than light receiving array PI2. In addition, light receiving array PI2 corresponds to an example of a 1st light receiving array, and light receiving array PI1 corresponds to an example of a 2nd light receiving array.

The size relationship between the light receiving array PI1 and the light receiving array PI2 is as follows. That is, length WPI1 which is the size of light receiving array PI1 in the width direction R is smaller than length WPI2 which is the size of light receiving array PI2 in the width direction R. Furthermore, the length LPI2 which is the size of the light receiving array PI2 in the measurement direction C is larger than the length LPI1 which is the size of the light receiving array PI1 in the measurement direction C. That is, in the present embodiment, both the dimension in the width direction R and the dimension in the measurement direction C of the light receiving array PI2 are formed larger than the light receiving array PI1.

In addition, the dimensional relationship between light receiving array PI1 and light receiving array PI2 is not limited to the above. For example, the length LPI1 and the length LPI2 may be made approximately equal, or the length LPI1 may be made larger than the length LPI2 contrary to the above. However, in FIG. 5 , the case where the length LPI2 is larger than the length LPI1 is shown for convenience of description.

On the other hand, the arrangements of light receiving array PI1 and light receiving array PI2 on substrate BA are as follows. That is, the light receiving array PI2 is arranged such that the shortest distance gPI2 from the light source 121 (specifically, the optical axis of the light source 121 ; the same applies hereinafter) to the light receiving array PI2 is smaller than the shortest distance gPI1 from the light source 121 to the light receiving array PI1 . In addition, the light receiving array PI2 is arranged such that the distance dPI2 from the light source 121 to the center position ci2 of the light receiving array PI2 is smaller than the distance dPI1 from the light source 121 to the center position ci1 of the light receiving array PI1 .

In addition, the central positions ci1 and ci2 may be substantially central positions of the light receiving arrays PI1 and PI2. The "substantial central position" mentioned here includes, for example: Although the light receiving arrays PI1 and PI2 have a plurality of light receiving elements, they are viewed as a whole when viewed as a plane figure (in other words, there are positions that will be located at a plurality of light receiving elements). The position of the center of gravity of the plane figure of the outline of the outermost periphery of the component), the position of the intersection of the center line of the plane figure in the measurement direction C and the center line in the width direction R, or the diagonal of the plane figure position of intersection, etc.

In addition, the arrangement|positioning form of light receiving array PI1 and light receiving array PI2 is not limited to the said case. For example, the shortest distance gPI2 and the shortest distance gPI1 may be made approximately equal, or contrary to the above, the shortest distance gPI2 may be made larger than the shortest distance gPI1. In addition, the distance dPI2 and the distance dPI1 may be made substantially equal, or the distance dPI2 may be made larger than the distance dPI1 contrary to the above. However, in FIG. 5 , for convenience of description, a case where the shortest distance gPI2 is smaller than the shortest distance gPI1 and the distance dPI2 is smaller than the distance dPI1 is shown.

In addition, the arrangements of light receiving arrays PI1 and PI2 and light receiving arrays PA1 and PA2 on the substrate BA are as follows. That is, the light-receiving arrays PI1, PI2 and the light-receiving arrays PA1, PA2 are configured such that the shortest distance gPI between the light-receiving array PI1 and the light-receiving array PI2 is shorter than the shortest distance gPA1 between the light-receiving array PI1 and the light-receiving array PA1 and the shortest distance between the light-receiving array PI2 and the light-receiving array PA2 The distance to gPA2 is small.

In addition, the arrangement|positioning form of light receiving array PI1, PI2 and light receiving array PA1, PA2 is not limited to the said case. For example, the shortest distance gPI and the shortest distances gPA1 and gPA2 may be substantially equal, or contrary to the above, the shortest distance gPI may be made larger than the shortest distances gPA1 and gPA2. However, in FIG. 5 , for convenience of description, the case where the shortest distance gPI is smaller than the shortest distances gPA1 and gPA2 is shown.

In this embodiment, a one-dimensional pattern is exemplified as an absolute pattern, and the light receiving arrays PA1 and PA2 corresponding thereto have a plurality of (for example, nine in this embodiment) light receiving elements (corresponding to an example of a first light receiving element), The plurality of light receiving elements are arranged along the measurement direction C (line Lcp) so as to receive light reflected by the reflection slots of the corresponding slot tracks SA1 and SA2 . In the plurality of light-receiving elements, as described above, each light-receiving or non-light-receiving element is processed as a bit, and an absolute position of 9 bits is represented. Therefore, the light-receiving signals received by the plurality of light-receiving elements are independently processed in the position data generation unit 130, and the absolute positions encrypted (encoded) into serial bit patterns are decoded based on the combination of these light-receiving signals. The light-receiving signals of the light-receiving arrays PA1 and PA2 are referred to as "absolute signals". Moreover, when using the absolute pattern different from this embodiment, light receiving array PA1, PA2 becomes a structure corresponding to this pattern.

The light receiving arrays PI1 and PI2 have a plurality of light receiving elements arranged along the measurement direction C (line Lcp) so as to receive light reflected by the reflection slots of the corresponding slot tracks SI1 and SI2, respectively. First, the light receiving array PI1 will be described as an example.

In this embodiment, a total of four groups of light receiving elements are arranged in one pitch of the incremental pattern of the slot track SI1 (one pitch of the projected image. That is, ε×P1.) (in FIG. 5 Indicated by "SET1"), further, along the measurement direction C, a plurality of sets of four light-receiving elements are further arranged. Since the reflective slots repeatedly form an incremental pattern at one pitch, each light receiving element generates a periodic signal with one cycle (360° in electrical angle) at one pitch when the disk 110 rotates. In addition, since four light receiving elements are arranged in one group corresponding to one pitch, adjacent light receiving elements in one group detect periodic signals having a mutual phase difference of 90°. These received light signals are called A-phase signal, B-phase signal (90° phase difference from A-phase signal), /A-phase signal (180° phase difference from A-phase signal), /B-phase signal (The phase difference with respect to the B-phase signal is 180°).

Since the incremental pattern indicates the position in one pitch, the signal of each phase in one group and the signal of each phase in the other corresponding group have values that change similarly. Therefore, signals of the same phase are accumulated over a plurality of groups. Therefore, four signals whose phases are different from each other by 90° are detected from a large number of light receiving elements of the light receiving array PI1 shown in FIG. 5 .

On the other hand, light receiving array PI2 is also comprised similarly to light receiving array PI1. That is, in one pitch of the incremental pattern of the slot track SI2 (one pitch of the projected image. That is, ε×P2.), a total of four sets of light receiving elements (in FIG. 5 "SET2" ), and a plurality of groups of four light-receiving elements are arranged along the measurement direction C. Therefore, four signals whose phases are different from each other by 90° are generated from the light receiving arrays PI1 and PI2 . These four signals are called "incremental signals". In addition, the incremental signal generated by the light-receiving array PI2 corresponding to the short-pitch slot track SI2 has a high resolution compared with other incremental signals, so it is called "high incremental signal". Compared with other incremental signals, the incremental signal generated by the corresponding light receiving array PI1 has a lower resolution, so it is called "low incremental signal".

In addition, in this embodiment, a case where four light receiving elements are included in one group with respect to one pitch of the incremental pattern is described as an example, but for example, two light receiving elements may be included in one group, The number of light receiving elements in one group is not particularly limited.

(2-3. Position data generation unit)

When measuring the absolute position of the motor M, the position data generator 130 acquires from the optical module 120 two absolute signals each having a bit pattern indicating the absolute position, and a high incremental signal and a high-increment signal including four signals whose phases are different by 90°. low delta signal. Then, the position data generator 130 calculates the absolute position of the motor M indicated by these signals based on the acquired signals, and outputs the calculated position data indicating the absolute position to the control device CT.

In addition, various methods can be used for generating the position data by the position data generating unit 130 and are not particularly limited. Here, the case where the absolute position is calculated based on the high incremental signal, low incremental signal, and absolute signal to generate position data will be described as an example.

As shown in FIG. 6 , the position data generating unit 130 includes an absolute position specifying unit 131 , a first position specifying unit 132 , a second position specifying unit 133 , and a position data calculating unit 134 . The absolute position specifying unit 131 binarizes the absolute signals from the light receiving arrays PA1 and PA2 respectively, and converts them into bit data representing an absolute position. Then, the absolute position is determined according to the predetermined correspondence between the bit data and the absolute position.

On the other hand, the first position specifying unit 132 subtracts the low delta signals with a phase difference of 180° among the low delta signals of the four phases from the light receiving array PI1 . In this way, by subtracting the signals having a phase difference of 180°, it is possible to cancel out manufacturing errors, measurement errors, and the like of reflection slots within one pitch. Here, the signals obtained by subtraction as described above are referred to as "first incremental signal" and "second incremental signal". The first incremental signal and the second incremental signal have a phase difference of 90° in electrical angle (abbreviated as "A-phase signal", "B-phase signal", etc.). Therefore, the first position specifying unit 132 specifies a position within one pitch based on these two signals. The method of specifying the position within one pitch is not particularly limited. For example, in the case where the low-incremental signal that is a periodic signal is a sine wave signal, as an example of the above-mentioned determination method, there is an arctan calculation for the division result of two sine wave signals, A phase and B phase, to calculate the electrical horn Methods. Alternatively, there is also the use of a tracking circuit to convert 2 sine wave signals into electrical degrees Methods. Alternatively, there is also a determination of the electrical angle corresponding to the values of the A-phase and B-phase signals in a pre-made table Methods. In addition, at this time, it is preferable that the first position specifying unit 132 performs analog-to-digital conversion of the two sine wave signals of the A phase and the B phase according to each detection signal.

The position data calculating unit 134 superimposes the position within one pitch specified by the first position specifying unit 132 and the absolute position specified by the absolute position specifying unit 131 . Accordingly, it is possible to calculate an absolute position with a higher resolution than an absolute position based on an absolute signal. In this embodiment, the resolution of the calculated absolute position corresponds to the number of slots of the short-pitch slot track SI2. That is, in this example, the resolution of the calculated absolute position is twice the resolution of the absolute position based on the absolute signal.

On the other hand, the second position specifying unit 133 performs the same processing as the above-mentioned first position specifying unit 132 on the high-increment signal from the light receiving array PI2, and specifies a high-precision position within one pitch from the two signals. Then, the position data calculation unit 134 superimposes the position within one pitch specified by the second position specifying unit 133 on the absolute position calculated from the aforementioned low incremental signal. As a result, it is possible to calculate an absolute position with higher resolution than the absolute position calculated from the low incremental signal.

The position data calculation unit 134 multiplies the absolute position calculated in this way to further increase the resolution, and then outputs it to the control device CT as position data representing a highly accurate absolute position. Here, the method of specifying a high-resolution absolute position from a plurality of pieces of position data having different resolutions is called an "accumulation method".

<3. Examples of effects of this embodiment>

In the embodiment described above, the encoder 100 has a plurality of types of slot tracks SI1, SI2 and light receiving arrays PI1, PI2, and the plurality of types of slot tracks SI1, SI2 respectively have incremental patterns with different pitches, The light receiving arrays PI1 and PI2 are configured to receive light reflected by a plurality of types of slot tracks SI1 and SI2, respectively. Thus, by using the multiplication and accumulation method of accumulating the multiplication processing of the low-increment signal of the light-receiving array PI1 and the multiplication processing of the high-increment signal of the light-receiving array PI2, the position data representing the absolute position of high resolution can be generated, and therefore, the realization of high resolution.

In addition, when the multiplication processing of the signal of the light receiving array PI1 and the multiplication processing of the signal of the light receiving array PI2 are integrated in this way, the accuracy of the final absolute position of the encoder 100 is affected by the accuracy of the high incremental signal output from the light receiving array PI2. The impact is relatively large. As mentioned above, in this embodiment, the length WPI1 of the light receiving array PI1 in the width direction R is smaller than the length WPI2 of the light receiving array PI2 in the width direction R. In other words, the length WPI2 of the light receiving array PI2 in the width direction R is larger than the length WPI1 of the light receiving array PI1 in the width direction R. Thereby, the light receiving area of the light receiving array PI2 which requires precision can be enlarged compared with the light receiving array PI1, and the light receiving quantity of the light receiving array PI2 can be increased. As a result, since the SN ratio of the light-receiving signal which is an analog signal of the light-receiving array PI2 increases, the precision of the subsequent multiplication process can be improved. Therefore, high resolution of the encoder 100 can be realized.

Furthermore, in the present embodiment, when the light receiving arrays PI1 and PI2 are arranged such that the shortest distance gPI2 from the light source 121 to the light receiving array PI2 is smaller than the shortest distance gPI1 from the light source 121 to the light receiving array PI1, the following effects are obtained. That is, with the above configuration, the light receiving array PI2 which has a relatively large influence on the accuracy of the absolute position can be brought closer to the light source 121 than the light receiving array PI1 , and thus the amount of light received by the light receiving array PI2 can be increased. Furthermore, the responsiveness of the light receiving array PI2 to a high incremental signal can also be improved.

Furthermore, in the present embodiment, when the light receiving arrays PI1 and PI2 are arranged such that the distance dPI2 from the light source 121 to the center position ci2 of the light receiving array PI2 is smaller than the distance dPI1 from the light source 121 to the center position ci1 of the light receiving array PI1 Next, the following effect is obtained. That is to say, with the above structure, the light receiving array PI2 which has a relatively large influence on the accuracy of the absolute position can be brought closer to the light source 121 than the light receiving array PI1, and thus the light receiving amount of the light receiving array PI2 can be further increased. Furthermore, the responsiveness of the high incremental signal of the light receiving array PI2 can be further improved.

Furthermore, in this embodiment, when the length LPI2 of the light receiving array PI2 in the measurement direction C is made larger than the length LPI1 of the light receiving array PI1 in the measurement direction C, the light receiving area of the light receiving array PI2 can be made larger than the length LPI1 of the light receiving array PI2. PI1 further expands, thereby further increasing the amount of light received by the light receiving array PI2.

Moreover, in this embodiment, in particular, the light-receiving array PI1 and the light-receiving array PI2 are arranged between two light-receiving arrays PA1 and PA2, and the two light-receiving arrays PA1 and PA2 are arranged in the width direction R so that the light source The manner in which 121 is sandwiched between them is substantially symmetrical. In such a structure, light receiving array PI1 and light receiving array PI2 are arrange|positioned in the limited area between light receiving array PA1, PA2. By constituting at least one of the following arrangements in this limited area as described above, the arrangement of the light receiving arrays PI1, PI2 can be optimized to achieve high resolution of the encoder 100. The configuration includes: making the length WPI2 of the light-receiving array PI2 in the width direction R larger than the length WPI1 of the light-receiving array PI1 in the width direction R; The shortest distance gPI1 is small; the distance dPI2 from the light source 121 to the center position ci2 of the light-receiving array PI2 is smaller than the distance dPI1 from the light source 121 to the center position ci1 of the light-receiving array PI1; and the length of the light-receiving array PI2 in the measuring direction C LPI2 is larger than length LPI1 of light receiving array PI1 in measurement direction C, etc.

In addition, in this embodiment, the shortest distance gPI between the light-receiving array PI1 and the light-receiving array PI2 is smaller than the shortest distance gPA1 between the light-receiving array PI1 and the light-receiving array PA1 and the shortest distance gPA2 between the light-receiving array PI2 and the light-receiving array PA2. In the case of a light-receiving array, the following effects are obtained. That is, in the encoder 100, due to the offset of the reflected image of the slot due to the eccentricity of the disk 110, and the limited area of the emitting surface of the light source 121, the light quantity distribution in the width direction R of each light receiving array becomes a trapezoidal shape. etc., if the interval between the light receiving arrays is small, crosstalk is likely to occur between adjacent light receiving arrays in the width direction R.

In addition, crosstalk due to diffuse reflection components of reflected light will be described. As shown in FIG. 7 , since there are many fine irregularities on the surface of the material 111 of the disc 110 , light emitted from the light source 121 is diffusely reflected (scattered) when reflected by the disc 110 .

FIG. 8 conceptually shows an example of the shape of the convex portion 112 among the fine unevenness of the material 111 . In addition, the length of each arrow of the diffuse reflection component in FIG. 8 indicates the magnitude of the intensity. In the example shown in FIG. 8, the convex part 112 has the upper surface 112a and the inclined side surface 112b which surrounds the periphery of the upper surface 112a. The upper surface 112a has a relatively flat shape, so the area irradiated by the incident light from obliquely above (in this example, the positive side of the Y-axis and the positive side of the Z-axis) is large, but the side surface 112b is obliquely illuminated by the incident light. The irradiated area is small. Therefore, with regard to the intensity of the diffuse reflection component generated by the incident light, as shown in FIG. The side scattering component Ls of the scattering is relatively small. Furthermore, among the forward scattering component Lf, the upward scattering component Lu, and the back scattering component Lb, the intensity of the forward scattering component Lf scattered in the regular reflection direction is the largest, and the upward scattering component Lu scattered upward is scattered in the direction opposite to the direction of incident light. The intensity of the backscattering component Lb is intermediate (larger than the side scattering component Ls). Therefore, in the distribution of diffuse reflection components as a whole, the direction along the Y-Z plane is dominant.

FIG. 9 shows the intensity distribution of the diffuse reflection component viewed from the positive X-axis direction, and FIG. 10 shows the intensity distribution of the diffuse reflection component viewed from the positive Z-axis direction. In addition, the length of each arrow in FIG. 9 indicates the intensity, and the distance from point E in FIG. 10 indicates the intensity. Utilizing the above-mentioned diffuse reflection of the convex portion 112, the intensity distribution of the diffuse reflection component on the surface of the disk 110 where a large number of fine convex portions 112 exist, as shown in FIGS. In this example, it has a long shape in the direction of the Y-Z plane), and has directionality in the Y-axis direction as a whole. More specifically, as shown in FIG. 10 , the intensity distribution of the diffuse reflection component has a roughly figure-of-eight distribution formed by connecting two circles arranged along the light traveling direction with the reflection position E as the center. , a distribution shape in which the circle on the far side in the traveling direction of light is larger than the circle on the near side in the traveling direction. That is, when two light-receiving arrays are arranged in the same direction with respect to the light source 121 in the optical module 120, between the two light-receiving arrays, scattered light of reflected light that should reach one light-receiving array reaches the other light-receiving array, etc. Crosstalk becomes a cause of noise. In addition, since the light receiving arrays farther from the light source 121 receive more diffuse reflection components of each other's light than the light receiving arrays close to the light source 121 , larger noise may be generated.

Furthermore, absolute positions are uniquely indicated based on the detected or undetected bit patterns of the respective light receiving arrays PA1 and PA2 for the absolute signals output by the light receiving arrays PA1 and PA2 . In terms of the nature of such signals, the light-receiving arrays PA1 and PA2 have relatively low noise immunity. In addition, the absolute signal output by the light receiving arrays PA1 and PA2 is different from the incremental signal, and will not become a repetitive signal (sine wave, etc.). The noise induced by array PI2 acceptance is difficult to reduce by filters. Therefore, it is preferable to avoid superposition of noise between light receiving array PI1 and light receiving array PA1 and between light receiving array PI2 and light receiving array PA2 as much as possible.

On the other hand, regarding the low incremental signal output by the light receiving array PI1 and the high incremental signal output by the light receiving array PI2 , the period of the latter is 1/2 of the former, and they are in a phase-equal relationship with each other. Therefore, by performing the difference between the A-phase signal and the B-phase signal and adding the in-phase signals between the plurality of light receiving elements, noises superimposed on each other are cancelled. Therefore, even if noise is superimposed on each other between the light receiving array PI1 and the light receiving array PI2, the influence will be relatively small.

In view of the above circumstances, in this embodiment, the shortest distance gPI between the light-receiving array PI1 and the light-receiving array PI2 whose mutual influence of noise is relatively small as described above is greater than the shortest distance gPI between the light-receiving arrays PI1 and PI2 whose mutual influence of noise is relatively large. Each light receiving array is arrange|positioned so that the shortest distance gPA1 of light receiving array PA1 and the shortest distance gPA2 of light receiving array PI2 and light receiving array PA2 are small. Thereby, it is possible to reduce the influence of the crosstalk between the light-receiving arrays caused by the shift of the reflected image of the slit and the shape of the light intensity distribution, and to reduce the influence of the intensity distribution based on the diffuse reflection component of the above-mentioned light. The diffuse reflection component from the light receiving array PI1 to the light receiving array PA1 and the diffuse reflection component from the light receiving array PI2 to the light receiving array PA2. Therefore, the reliability of position data can be improved.

Furthermore, in the present embodiment, the encoder 100 is particularly configured as a reflective encoder. In a reflective encoder, since the offset of the slot due to the eccentricity of the disc 110 described above is multiplied on the reflected image, and the light distribution is likely to become a trapezoidal shape due to the use of the light source 121 that emits diffused light, if the received light When the interval between arrays is small, crosstalk is more likely to occur between adjacent light-receiving arrays in the width direction R. Therefore, it can be said that the arrangement form of each light-receiving array in this embodiment is more effective for application to a reflective encoder. In addition, by configuring the encoder 100 as a reflective encoder, the light receiving arrays PI1 , PI2 and the light receiving arrays PA1 , PA2 can be arranged close to the light source 121 , so the encoder 100 can be downsized.

＜4. Modifications＞

As above, one embodiment has been described in detail with reference to the drawings. However, the range of technical ideas described in the claims is not limited to the embodiments described here. It is obvious that various changes, corrections, combinations, and the like can be conceived within the scope of the technical idea as long as a person having ordinary knowledge in the technical field to which the present embodiment belongs. Therefore, it is a matter of course that technologies after such changes, corrections, combinations, etc. are made also belong to the scope of technical ideas.

(4-1. Arranging the light receiving array PI1 on the outer peripheral side than the light receiving array PI2)

In the above-mentioned embodiment, the case where the light-receiving array PI1 is disposed on the inner peripheral side of the light-receiving array PI2 has been described as an example. However, for example, as shown in FIG. on the outer peripheral side. The dimensional relationship and arrangement form of each light-receiving array in this modified example are also the same as those in the above-mentioned embodiment. That is to say, the length WPI2 of the light-receiving array PI2 in the width direction R is larger than the length WPI1 of the light-receiving array PI1 in the width direction R, and the shortest distance gPI2 from the light source 121 to the light-receiving array PI2 is shorter than the shortest distance gPI2 from the light source 121 to the light-receiving array PI1. The distance from gPI1 is small. In addition, the distance dPI2 from the light source 121 to the center position ci2 of the light receiving array PI2 is smaller than the distance dPI1 from the light source 121 to the center position ci1 of the light receiving array PI1, and the length LPI2 of the light receiving array PI2 in the measuring direction C is shorter than that of the light receiving array PI1 in The length LPI1 in the measurement direction C is large. In addition, the shortest distance gPI between the light receiving array PI1 and the light receiving array PI2 is smaller than the shortest distance gPA2 between the light receiving array PI1 and the light receiving array PA2 and the shortest distance gPA1 between the light receiving array PI2 and the light receiving array PA1. Although not shown, in the case of this modified example, four slot tracks are arranged in the order of SA1, SI2, SI1, and SA2 from the inner side toward the outer side in the width direction R on the disc 110 .

Also in this modified example, the same effect as that of the above-mentioned embodiment is obtained. Furthermore, in the case of adopting the above structure, the stability of the low incremental signal against eccentricity can be improved. In other words, generally, the detection error caused by the eccentricity of the disk 110 has a property of depending on the radius of the slot track, and the error is large if the radius is small, and the error is small if the radius is large. In this modified example, the light receiving array PI1 is arranged on the outer peripheral side than the light receiving array PI2, and the slot track SI1 is arranged on the outer peripheral side in the disk 110, so that the radius of the slot track SI1 can be increased. As a result, the detection error due to the eccentricity of the light receiving array PI1 can be reduced, and the stability against eccentricity can be improved. Therefore, it is preferable to adopt the structure of the above-described embodiment when improving the stability of the high-increment signal against eccentricity, and to adopt the structure when improving the stability of the low-increment signal against eccentricity.

(4-2. Arranging the absolute light-receiving array of one structure on the inner peripheral side)

In the above-mentioned embodiment, the case where the light-receiving arrays PA1 and PA2 are arranged offset in the width direction R to form two tracks has been described as an example, but the arrangement structure of the light-receiving arrays PA1 and PA2 is not limited to this, and can be constituted as one.

As shown in FIG. 12, in this modification, the light receiving array PA corresponding to the absolute pattern is arrange|positioned on the inner peripheral side of the light receiving array PI1. Although not shown, in the case of this modified example, three slot tracks are concentrically arranged in the order of SA, SI1, and SI2 from the inner side toward the outer side in the width direction R on the disk 110 . The light receiving array PA has two types of light receiving arrays PA1 and PA2. The light receiving elements p1 and p2 respectively constituting the light receiving arrays PA1 and PA2 are alternately arranged along the measurement direction C (line Lcp), whereby the two light receiving arrays PA1 and PA2 constitute a single track (one) light receiving array PA. In the light-receiving arrays PA1 and PA2, the reflected light from the slot track SA is received, and an absolute signal having a bit pattern of the number of light-receiving elements is generated. In addition, the light receiving array PA corresponds to an example of the 3rd light receiving array.

In this example, both the arrangement pitch of the light receiving elements p1 and the arrangement pitch of the light receiving elements p2 correspond to the minimum length (pitch P1) of the reflection slot of the slot track SA in the measurement direction C (the minimum length of the projected image. That is, ε×P1.), the length of each light receiving element p1, p2 in the measurement direction C is equal to half of ε×P1. As a result, the light-receiving arrays PA1 and PA2 are offset from each other in the measurement direction C by 1/2 the length of 1 bit (corresponding to half the pitch P1). When corresponding to the transition point of the bit pattern, the absolute position can be calculated using the detection signal from the light-receiving array PA2 or vice versa, thereby improving the detection accuracy of the absolute position. In addition, the length of each light receiving element p1, p2 in the measurement direction C is not limited to the above, and may be a length other than half of ε×P1.

The dimensional relationship and arrangement form of each light-receiving array in this modified example are the same as those in the above-mentioned embodiment. That is to say, the length WPI2 of the light-receiving array PI2 in the width direction R is larger than the length WPI1 of the light-receiving array PI1 in the width direction R, and the shortest distance gPI2 from the light source 121 to the light-receiving array PI2 is shorter than the shortest distance gPI2 from the light source 121 to the light-receiving array PI1. The distance from gPI1 is small. In addition, the distance dPI2 from the light source 121 to the center position ci2 of the light receiving array PI2 is smaller than the distance dPI1 from the light source 121 to the center position ci1 of the light receiving array PI1, and the length LPI2 of the light receiving array PI2 in the measuring direction C is shorter than that of the light receiving array PI1 in The length LPI1 in the measurement direction C is large. Furthermore, the shortest distance gPI between the light receiving array PI1 and the light receiving array PI2 is smaller than the shortest distance gPA between the light receiving array PI1 and the light receiving array PA.

Also in this modified example, the same effect as that of the above-mentioned embodiment is obtained. Furthermore, in the case of employing the above configuration, it is possible to reduce the size of the encoder 100 . That is, according to this modified example, two light-receiving arrays PA1 and PA2 constitute one light-receiving array PA, so both the slot track SA and the light-receiving array PA can be constituted as one track. Therefore, the disc 110 and the optical module 120 can be downsized, and the encoder 100 can also be downsized.

(4-3. Arranging the absolute light-receiving array of one structure on the outer peripheral side)

In the above modification (4-2), the case where the photoreceiving array PA is arranged on the inner peripheral side than the photoreceiving arrays PI1 and PI2 has been described as an example, but for example, the photoreceiving array PA may be arranged as shown in FIG. PA is arrange|positioned at the outer peripheral side rather than light receiving array PI1, PI2.

In this modified example, the light receiving array PA corresponding to the absolute pattern is arranged on the inner peripheral side of the light receiving array PI2. Although not shown, in the case of this modified example, three slot tracks are concentrically arranged in the order of SI1, SI2, and SA on the disk 110 from the inner side toward the outer side in the width direction R. The dimensional relationship and arrangement form of each light-receiving array in this modification are also the same as those in the modification (4-2). It is preferable to adopt the structure of this modification when improving the stability of the absolute signal against eccentricity, and to adopt the above-mentioned modification (4-2) when improving the stability of the incremental signal against eccentricity.

(4-4.Through-through encoder)

In the above, the case of a so-called reflective encoder in which the light source and the light receiving array are arranged on the same side with respect to the slot track of the disk 110 has been described as an example, but the present invention is not limited thereto. That is, a so-called transmissive encoder may be used in which the light source and the light receiving array are arranged on opposite sides of the disc 110 . In this case, in the disk 110, each slit of the slot tracks SA1, SA2, SI1, and SI2 may be formed as a transparent slit, or the portion other than the groove may be roughened by sputtering or the like, and the transparent slit may be coated. It is formed by materials with low pass rate. In addition, in this modified example, the light source 121 and the light receiving arrays PA1, PA2, PI1, PI2 are arranged to face each other across the disk 110, but the optical module 120 of this modified example includes the light source and the light receiving array formed as separate bodies in this way.

In this modified example, the shortest distances gPI1 , gPI2 , distances dPI1 , dPI2 , and other distances based on the light source 121 in the above-described embodiment are located at positions based on the optical axis of the light source 121 . Even when such a transmissive encoder is used, the same effects as those of the above-described embodiment can be obtained.

(4-5. Others)

In the above, the case where two slot tracks SI1 and SI2 having incremental patterns with different pitches are provided on the disk 110 has been described, but three or more slot tracks having incremental patterns with different pitches may also be provided. . In this case, too, a high resolution can be achieved cumulatively. At this time, for example, at least one of the light receiving arrays PA1 and PA2 may be used for the incremental signal.

In addition, above, the light receiving arrays PA1 and PA2 respectively have 9 light receiving elements and the absolute signal represents the absolute position of 9 bits. However, the number of light receiving elements may be other than 9, and the absolute signal bit The number of arity is also not limited to 9. In addition, the number of light receiving elements of light receiving arrays PI1 and PI2 is not particularly limited to the number of the above-mentioned embodiment, either.

In addition, although the optical module 120 has demonstrated the case where the light receiving array PA1 and PA2 for absolute signals are provided above, it does not necessarily need to provide the light receiving array PA1 and PA2. For example, instead of the light-receiving arrays PA1 and PA2 , a light-receiving element array for the origin indicating the position of the origin using detection signals from the respective light-receiving elements may be provided. In this case, the slot tracks SA1 and SA2 of the disk 110 are formed as a pattern for the origin.

In addition, "perpendicular", "parallel", and "equal" in the above description are not strict meanings. That is, "perpendicular", "parallel", and "equal" mean that design and manufacturing tolerances and errors are allowed, and they are "substantially perpendicular", "substantially parallel", and "substantially equal".

Claims (10)

1. An encoder, characterized in that the encoder has: a plurality of slot tracks each having a plurality of slots arranged along the measuring direction; a light source configured to emit light toward the plurality of slot tracks; a first light-receiving array configured to receive light reflected or transmitted by the slot track having an incremental pattern; and a second light-receiving array configured to receive light reflected by the slot track having an incremental pattern whose pitch is longer than other incremental patterns, and the second light-receiving array is arranged in a width direction perpendicular to the measurement direction The size is smaller than the first light-receiving array. 2. The encoder of claim 1, wherein The first light receiving array is arranged such that the shortest distance from the optical axis of the light source is shorter than the shortest distance from the optical axis to the second light receiving array. 3. The encoder of claim 1, wherein The first light receiving array is arranged such that the distance from the optical axis of the light source to the center of the first light receiving array is smaller than the distance from the optical axis to the center of the second light receiving array. 4. The encoder of claim 2, wherein The first light receiving array is arranged such that the distance from the optical axis of the light source to the center of the first light receiving array is smaller than the distance from the optical axis to the center of the second light receiving array. 5. The encoder according to any one of claims 1 to 4, characterized in that, The size of the first light receiving array in the measurement direction is larger than that of the second light receiving array. 6. The encoder according to any one of claims 1 to 4, characterized in that, The encoder further has two third light-receiving arrays, and the two third light-receiving arrays are arranged symmetrically with the optical axis sandwiched between them in the width direction, and receive the received light respectively. light reflected or transmitted by said slot track having an absolute pattern, The first light receiving array and the second light receiving array are arranged between the two third light receiving arrays in the width direction. 7. The encoder of claim 6, wherein The first light-receiving array and the second light-receiving array are arranged in the width direction so as to sandwich the optical axis therebetween, The first light-receiving array, the second light-receiving array, and the third light-receiving array are configured such that the shortest distance between the first light-receiving array and the second light-receiving array is shorter than the first light-receiving array and the third light-receiving array. The shortest distance between the light receiving array and the shortest distance between the second light receiving array and the third light receiving array is small. 8. The encoder according to any one of claims 1 to 4, characterized in that, The light source is a point light source configured to emit diffused light to the plurality of slot tracks, Each of the slots included in the slot track is configured to reflect light emitted from the point light source, The first light-receiving array, the second light-receiving array, and the third light-receiving array are each configured to receive light reflected by the groove track. 9. A motor with an encoder, characterized in that the motor with an encoder has: a linear motor in which a movable body moves relative to a fixed body, or a rotary motor in which a rotor rotates relative to a stator; and The encoder according to any one of claims 1 to 8, which is configured to detect at least one of the position and speed of the movable body or the rotor. 10. A servo system, characterized in that the servo system has: A linear motor in which the movable body moves relative to a fixed body, or a rotary motor in which the rotor rotates relative to the stator; The encoder according to any one of claims 1 to 8, which is configured to detect at least one of the position and speed of the movable body or the rotor; and A control device configured to control the linear motor or the rotary motor based on a detection result of the encoder.