JP2013221795A - Encoder and driving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To highly accurately detect position information.SOLUTION: An encoder includes a code plate having a pattern, which is a pattern indicating the position information of a driven member, where absolute bits indicating position information as an absolute position on the basis of the combination of a first state and a second state and incremental bits indicating the first state are alternately arranged at predetermined pitches in the detection direction of the position information, a sensor part for detecting the pattern of the code plate and outputting an output signal indicating the first state and the second state corresponding to the detected pattern, a signal generation part for generating absolute position information corresponding to the absolute bit and incremental information corresponding to the incremental bit on the basis of the output signal output from the sensor part, and a detection part for detecting the position information of the driven member on the basis of the absolute position information and the incremental signal generated by the signal generation part.

Description

  The present invention relates to an encoder and a drive device.

  In recent years, high-resolution encoders capable of detecting a position finer than the width of an absolute pattern are known. Such an encoder includes, for example, an absolute track and an incremental track on a code plate such as a scale, and includes a sensor unit having a detection element for an absolute track and a detection element for an incremental track (for example, , See Patent Document 1). Such an encoder detects the absolute position using an absolute track, and performs position and angle subdivision processing using the provided incremental track to detect position information with high resolution.

JP 2010-66129 A

However, for example, the encoder as described above has two tracks of an absolute track and an incremental track on a code plate such as a scale. In this case, in the encoder as described above, since it is necessary to arrange the detection element so that the detection signal of the absolute track and the detection signal of the incremental track are within the standard, accuracy is required for mounting the sensor unit. Therefore, for example, when there is a deviation in the mounting position of the sensor unit, the position information detection accuracy of the encoder as described above may decrease.
Thus, the encoder as described above has a problem that it is difficult to detect position information with high accuracy.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide an encoder and a driving apparatus that can detect position information with high accuracy.

  In order to solve the above problem, an embodiment of the present invention is a pattern indicating position information of a driven body, and the position information is set as an absolute position based on a combination of a first state and a second state. A code plate having a pattern in which an absolute bit indicating and an incremental bit indicating the first state are alternately arranged at a predetermined pitch in the detection direction of the position information, and detecting the pattern of the code plate A sensor unit that outputs output signals indicating the first state and the second state corresponding to the detected pattern, and the absolute bit based on the output signal output from the sensor unit. A signal generator that generates absolute position information and incremental information corresponding to the incremental bits, and a signal generator that generates the absolute position information. Based on the absolute position information and the incremental information is, the an encoder, characterized in that it comprises a detector for detecting the position information of the driven body.

  Moreover, one embodiment of the present invention is a drive device comprising the encoder described above and the driven body connected to the code plate or the sensor unit.

  According to the present invention, position information can be detected with high accuracy.

It is a schematic block diagram which shows an example of a structure of the encoder by 1st Embodiment. It is a schematic block diagram which shows the structure of the encoder by 1st Embodiment. It is a figure which shows an example of operation | movement of the encoder in 1st Embodiment. It is a figure which shows an example of the operation | movement of the bit determination by likelihood in this embodiment. It is a figure which shows an example of the production | generation process of the incremental information in this embodiment. It is a schematic block diagram which shows the structure of the encoder by 2nd Embodiment. It is a figure which shows an example of the subdivision process of the incremental information in this embodiment. It is a figure which shows another example of a structure of the line sensor part in this embodiment. It is a schematic block diagram which shows the structure of the stage apparatus in this embodiment.

  Hereinafter, an encoder according to an embodiment of the present invention will be described with reference to the drawings.

[First Embodiment]
FIG. 1 is a schematic configuration diagram showing an example of the configuration of the encoder 1 according to the first embodiment.
FIG. 2 is a schematic block diagram showing the configuration of the encoder 1.
1 and 2, the movement direction of the scale 6 will be described below as the X-axis direction.

FIG. 1A is a diagram illustrating a case where the scale 6 and the sensor unit 9 are viewed from the Z-axis direction. FIG. 1B is a diagram illustrating a case where the scale 6 and the sensor unit 9 are viewed from the X-axis direction.
Here, as an example, the encoder 1 detects position information (for example, the moving direction, moving amount, moving speed, or displacement of the scale 6) of the scale 6 that moves in a predetermined moving direction (for example, the X-axis direction). A case where the optical linear encoder is used will be described. In the present embodiment, the encoder 1 will be described with reference to an example of a reflective optical linear encoder.
1 and 2, the encoder 1 includes a scale 6, a sensor unit 9, and a signal processing unit 8.

  The sensor unit 9 (detection head) includes the light source unit 2 and the line sensor unit 7 and is disposed so as to maintain a predetermined distance from the scale 6. At least the light source unit 2 and the line sensor unit 7 of the sensor unit 9 are integrally supported by a support member of the sensor unit 9 (in this example, the detection substrate 5). The scale 6 and the sensor unit 9 move relatively in the movement direction (X-axis direction).

  The light source unit 2 is, for example, a light emitting element such as a laser diode that emits laser light, and irradiates the scale 6 with irradiation light (laser light) based on a drive signal supplied from a driver unit 81 described later.

The scale 6 (symbol plate) is movable relative to the light source unit 2 at least in the moving direction (here, one direction such as the X-axis direction), and irradiated with irradiation light. The scale 6 has a pattern 60 formed along the moving direction (X-axis direction). Here, the pattern 60 is a pattern indicating position information of a driven body (for example, a stage), and the absolute bit 61 and the incremental bit 62 are predetermined in the position information detection direction (eg, X-axis direction). Are alternately arranged at a pitch (pattern pitch D2).
Here, the absolute bit 61 is a dark part (non-reflective part) that is in a state (first state) indicating logic “0” and a bright part (reflective) that is in a state (second state) indicating logic “1”. The position information is shown as the absolute position of the scale 6 based on the combination of (part). In FIG. 2, the absolute bit 61 in the state indicating logic “0” is indicated as an absolute bit 610, and the absolute bit 61 in the state indicating logic “1” is indicated as an absolute bit 611. The logic “0” state corresponds to the dark portion pattern in the light / dark pattern in the pattern 60, and the logic “1” state corresponds to the light portion pattern in the light / dark pattern in the pattern 60. State.

The detection direction is the movement direction of the driven body or the relative movement direction of the scale 6 and the sensor unit 9.
In addition, the incremental bit 62 is formed by, for example, a dark part (non-reflective part) that is a state (first state) indicating logic “0”.

Further, the absolute bit 61 and the incremental bit 62 have the same width (D1) in the detection direction (X-axis direction) for one track, and the width in the detection direction is a half of the pattern pitch D2. It is formed as follows. The absolute bit 61 and the incremental bit 62 are formed with a width D1 in the detection direction (X-axis direction) of 10 μm (micrometer) and a pattern pitch D2 of 20 μm, for example.
The scale 6 reflects the irradiation light emitted from the light source unit 2 by the pattern 60 described above, and irradiates the line sensor unit 7 with light according to the reflected pattern 60.

The line sensor unit 7 is, for example, a line sensor (detection element group) in which a plurality of light receiving elements 70 (detection elements) are arranged in a line shape in the detection direction (X-axis direction). Similar to the light source unit 2, the line sensor unit 7 is disposed on the detection substrate 5 so as to face the pattern 60 of the scale 6. Here, the plurality of light receiving elements 70 are arranged in a detection direction (X-axis direction) with a pitch equal to or less than a half width D1 of the pattern pitch D2. For example, the five light receiving elements 70 are arranged at a pattern pitch D2, and the sensor pitch D3 is arranged at 4 μm. The line sensor unit 7 includes, for example, 50 light receiving elements 70 (for 10 pattern pitches D2).
The line sensor unit 7 outputs a plurality of detection signals (data string X1) obtained by detecting the pattern 60 by the plurality of light receiving elements 70 as output signals. In this way, the sensor unit 9 detects the pattern 60 of the scale 6 from the reflected light from the scale 6, and the logic “0” state and the logic “1” corresponding to the detected pattern 60 are detected. An output signal indicating the state is output.

  The signal processing unit 8 performs irradiation control of the light source unit 2, detects position information of the scale 6 in the movement direction (X-axis direction) based on an output signal output from the line sensor unit 7, and detects the detected position information ( For example, output position x). The signal processing unit 8 includes a signal generation unit 3, a position detection unit 4, and a driver unit 81.

  The driver unit 81 generates a drive signal (for example, a drive current) that drives light emission of the light source unit 2, and supplies the generated drive signal to the light source unit 2.

Based on the output signal output from the sensor unit 9, the signal generation unit 3 includes absolute position information (ABS information) corresponding to the absolute bit 61 and incremental information (INC information, for example, an incremental signal) corresponding to the incremental bit 62. ) And generate. For example, the signal generation unit 3 calculates a likelihood to be described later based on an output signal (a plurality of detection signals (data sequence X1)) output from the sensor unit 9, and based on the calculated likelihood, the data sequence The output signal corresponding to each of the absolute bit 61 and the incremental bit 62 in X1 is determined. The signal generation unit 3 generates absolute position information (for example, a 10-bit code) based on the output signal corresponding to the absolute bit 61. The signal generator 3 outputs the generated absolute position information to the position detector 4.
Here, the incremental information (INC information) is information for executing an interpolation process, which will be described later, and is, for example, an incremental signal or a data string that is a periodic signal whose phase changes according to the position.

Further, the signal generation unit 3 generates incremental information based on at least two detection signals among the plurality of detection signals output from the sensor unit 9. Here, the at least two detection signals are detection signals detected by the light receiving element 70 corresponding to, for example, positions shifted from each other by the pattern pitch D2 in the data string X1. That is, at least two detection signals are detection signals detected by the light receiving element 70 corresponding to positions shifted (shifted) by a distance that is an integral multiple of the pattern pitch D2, for example. The signal generation unit 3 generates incremental information (eg, incremental signal) based on a predetermined logical operation (eg, logical sum operation) of the at least two detection signals. The signal generation unit 3 outputs the generated incremental information (INC information) to the position detection unit 4.
The signal generation unit 3 includes a bit determination unit 31, an ABS information generation unit 32, and an INC information generation unit 33.

  The bit determination unit 31 (determination unit) determines a detection signal corresponding to the absolute bit 61 among the plurality of detection signals, based on the likelihood calculated based on the plurality of detection signals (data string X1). In addition, the bit determination unit 31 determines a detection signal corresponding to the incremental bit 62 among the plurality of detection signals based on the detected signal corresponding to the determined absolute bit 61. Details of the determination operation of the absolute bit 61 and the incremental bit 62 by the bit determination unit 31 will be described later.

  The ABS information generation unit 32 generates absolute position information (ABS information) based on the detection signal corresponding to the absolute bit 61 determined by the bit determination unit 31. Here, the absolute position information is, for example, 10-bit pattern data (code data), and the ABS information generation unit 32 generates based on the detection signal for 10 bits determined as the absolute bit 61. The ABS information generation unit 32 outputs the generated absolute position information (ABS information) to the position detection unit 4.

  The INC information generation unit 33 is based on, for example, a detection signal detected by the light receiving element 70 corresponding to a position shifted (shifted) by an integer multiple of the pattern pitch D2 among the plurality of detection signals (data string X1). Incremental information is generated. The INC information generation unit 33 outputs the generated incremental information to the position detection unit 4. The detailed generation operation of the incremental information in the INC information generation unit 33 will be described later.

  The position detection unit 4 detects the position information of the driven body based on the absolute position information (ABS information) and incremental information (INC information) generated by the signal generation unit 3. The position detection unit 4 outputs the detected position information to the outside of the encoder 1. The position detection unit 4 includes an absolute address processing unit 41, an interpolation processing unit 42, and a synthesis processing unit 43.

  The absolute address processing unit 41 converts the data into absolute address data corresponding to the absolute address of the scale 6 based on the 10-bit pattern data which is the absolute position information output from the signal generating unit 3 (ABS information generating unit 32). . The absolute address processing unit 41 outputs the converted (generated) absolute address data to the synthesis processing unit 43.

  The interpolation processing unit 42 performs interpolation processing based on the incremental information output from the signal generation unit 3 (INC information generation unit 33), and generates interpolation data (relative position information). The interpolation processing unit 42 outputs the generated interpolation data to the synthesis processing unit 43.

  The synthesizing processing unit 43 synthesizes the absolute address data output from the absolute address processing unit 41 and the interpolation data output from the interpolation processing unit 42, and combines the position information (for example, scale 6). Position).

Next, the operation of the encoder 1 in this embodiment will be described.
FIG. 3 is a diagram illustrating an example of the operation of the encoder in the embodiment.
In FIG. 3, first, the driver unit 81 of the signal processing unit 8 supplies a drive signal to the light source unit 2 to cause the light source unit 2 to emit light.
The light source unit 2 irradiates the pattern 60 of the scale 6 with irradiation light, and the line sensor unit 7 outputs a plurality of detection signals (data string X1) detected by the plurality of light receiving elements 70 as output signals (FIG. 3). The waveform W1) is output to the signal generator 3.

  Next, the bit determination unit 31 of the signal generation unit 3 generates a detection signal corresponding to the absolute bit 61 among the plurality of detection signals based on the likelihood calculated based on the plurality of detection signals (data string X1). judge. In addition, the bit determination unit 31 determines a detection signal corresponding to the incremental bit 62 among the plurality of detection signals based on the detected signal corresponding to the determined absolute bit 61.

Based on the detection signal corresponding to the absolute bit 61 determined by the bit determination unit 31, the ABS information generation unit 32 uses 10-bit pattern data “1101001110” as shown in FIG. 3 as absolute position information (ABS information). Generate. The ABS information generation unit 32 outputs the generated absolute position information (ABS information) to the position detection unit 4.
Further, the INC information generation unit 33 performs an incremental as shown by the waveform W2 in FIG. 3 based on the detection signal detected by the light receiving element 70 corresponding to the position shifted (shifted) by an integral multiple of the pattern pitch D2. Information (INC information) is generated. The INC information generation unit 33 outputs the generated incremental information to the position detection unit 4.

Next, the absolute address processing unit 41 of the position detection unit 4 converts the absolute position information output from the ABS information generation unit 32 into absolute address data corresponding to the absolute address of the scale 6. In addition, the interpolation processing unit 42 performs an interpolation process based on the incremental information output from the INC information generation unit 33, and generates interpolation data. Here, as described above, since the five light receiving elements 70 are provided in the pattern pitch D2, the interpolation processing unit 42 is, for example, five light receiving elements 70 (for 5 bits of the data string X1). Can be generated.
The combining processing unit 43 combines the absolute address data output from the absolute address processing unit 41 and the interpolation data output from the interpolation processing unit 42, and outputs the combined position information.
In FIG. 3, the position information detection position is the position P <b> 1, and the position detection unit 4 generates position information corresponding to the position P <b> 1 and outputs the generated position information to the outside of the encoder 1.

Next, with reference to FIG. 4, the determination processing of the absolute bit 61 and the incremental bit 62 by the bit determination unit 31 will be described.
In the present embodiment, since information corresponding to the absolute bit 61 and information corresponding to the incremental bit 62 are mixed in one track in the pattern 60, the encoder 1 includes a plurality of information detected by the sensor unit 9. Of these detection signals, it is necessary to determine a detection signal corresponding to the absolute bit 61 and a detection signal corresponding to the incremental bit 62.

  Therefore, the bit determination unit 31 according to the present embodiment calculates the likelihood based on the plurality of detection signals (data string X1), and the detection signal corresponding to the absolute bit 61 and the incremental bit based on the calculated likelihood. A detection signal corresponding to 62 is determined. The reason why the bit determination unit 31 determines based on the likelihood is that, when the encoder 1 is attached to a drive device or the like, it is caused by a gap variation between the sensor unit 9 and the scale 6, a deviation in the attitude of the sensor unit 9, etc. This is because the determination of the absolute bit 61 and the incremental bit 62 becomes probabilistic.

Bit determination unit 31, for example, if the m-th data P _m of the data sequence X1, which is the output signal of the line sensor unit 7 is assumed to correspond to the absolute bit 61, m th 1 before and after the bit (wide D1 ) The distant data corresponds to the incremental bit 62. Here, since one bit corresponds to (5/2) of the light receiving elements 70, the position of the light receiving element 70 corresponding to the incremental bit 62 is expressed by the following equation (1).

Incremental bit 62 position (th) = m ± (5/2 + 5 × n)
= M ± (2.5 + 5 × n) (1)

Here, n is an integer of 1 or more.
Since the position of the light receiving element 70 is an integer, the position of the incremental bit 62 is expressed as a formula (2) written by rounding off “2.5”.

  Incremental bit 62 position (th) = m ± (3 + 5 × n) (2)

Here, when the mth is “0” (m = 0), the positions of the incremental bits 62 are as follows: -13th, -8th, -3rd, 3rd, 8th, 13th .. That is, the output signals P _{(−5 × n + 3)} ,..., P ₍₋₁₃₎ , P ₍₋₈₎ , P ₍₋₃₎ , P ₃ , P ₈ , P of the light receiving element corresponding to the incremental bit 62 ₁₃ ,... P _{(5 × n + 3)} is in a “0” state (first state). The bit determination unit 31 calculates the likelihood by adding the output signal corresponding to the incremental bit 62 as shown in the following equation (3).

Likelihood = P _{(−5 × n + 3)} +... + P ₍₋₁₃₎ + P ₍₋₈₎ + P ₍₋₃₎ + P ₃ + P ₈ + P ₁₃
+ ... + P _{(5 × n + 3)} (3)

Here, the closer the calculated likelihood value is to “0”, the higher the possibility that the m-th data P _m is the absolute bit 61. Therefore, the bit determination unit 31 changes the m-th and calculates the likelihood based on Equation (3) a plurality of times, and the data P _m whose calculated likelihood value is closest to “0” is the absolute bit. It is determined that this is a detection signal of the light receiving element 70 corresponding to 61.

For example, FIG. 4 shows an example of determining whether any of the light receiving elements 701 to 705 among the 50 light receiving elements 70 is the absolute bit 61.
FIG. 4A shows an example in which the bit determination unit 31 calculates the likelihood assuming that the light receiving element 702 is the absolute bit 61. In this case, since the light receiving element 702 is at a position corresponding to the absolute bit 61, the calculated likelihood value is substantially “0”.

  FIG. 4B shows an example in which the bit determination unit 31 calculates the likelihood assuming that the light receiving element 704 is the absolute bit 61. In this case, since the light receiving element 702 corresponds not to the position corresponding to the absolute bit 61 but to the incremental bit 62, the calculated likelihood value is almost “6”.

As described above, the bit determination unit 31 calculates the likelihood for each of the light receiving elements 701 to 705, and selects the light receiving element 70 with the likelihood value closest to “0” among the light receiving elements 701 to 705 as an absolute bit. The light receiving element 70 corresponding to 61 is determined. The bit determining unit 31 determines that the (m ± 5) th light receiving element 70 is also the light receiving element 70 corresponding to the absolute bit 61. In this case, since the five light receiving elements 70 are arranged in the pattern pitch D2, the bit determining unit 31 reliably calculates the light receiving element 70 corresponding to the absolute bit 61 by calculating the likelihood five times. can do.
In addition, as described above, when the position of the light receiving element 70 corresponding to the absolute bit 61 is (m = 0), the bit determination unit 31, -13th, -8th, -3rd The third, eighth, thirteenth,... Light receiving elements 70 are determined as the light receiving elements 70 corresponding to the incremental bits 62.

Next, incremental information generation processing by the INC information generation unit 33 will be described with reference to FIG.
FIG. 5 is a diagram illustrating an example of incremental information generation processing according to the present embodiment.
In FIG. 5, the INC information generation unit 33 shifts the output signal (data string X1) of the sensor unit 9 (line sensor unit 7) as shown by the waveform W1 by the pattern pitch D2 and shows the waveform W3, for example. A shift signal (shift data string X2) is generated. Furthermore, the INC information generation unit 33 shifts the shift data string X2 as shown by the waveform W3 by the pattern pitch D2 to generate a shift signal (shift data string X3) as shown by the waveform W4.
Here, the shift amount of the shift signal (shift data string X2 and shift data string X3) corresponds to shifting the pattern pitch D2, that is, five light receiving elements 70. For example, the shift amount of the shift data sequence X2 is the pattern pitch D2 with respect to the data sequence X1, and the shift amount of the shift data sequence X3 is twice the pattern pitch D2 with respect to the data sequence X1.

  The INC information generation unit 33 stores, for example, the above-described data string X1 acquired from the sensor unit 9 in a shift register, and an integer multiple of the pattern pitch D2 (an integer multiple of “5”) by a clock signal having a predetermined frequency. ) May be shifted to generate shift signals (shift data string X2 and shift data string X3). In addition, the INC information generation unit 33 stores, for example, the above-described data string X1 acquired from the sensor unit 9 in a memory or a register, and reads data separated by an integer multiple of the pattern pitch D2 (an integer multiple of “5”). Thus, shift signals (shift data sequence X2 and shift data sequence X3) may be generated.

For example, the INC information generation unit 33 performs an OR operation (OR operation) on the data string X1, the shift data string X2, and the shift data string X3 to generate incremental information (INC information) as indicated by the waveform W2.
Here, the incremental information (INC information) is generated by performing an OR operation (OR operation) with the shift data string X2 and the shift data string X3 for all data (50 data) of the data string X1. Alternatively, the incremental information (incremental signal) may be generated only for the detection signal of the light receiving element 70 at a predetermined position among the 50 light receiving elements 70. That is, the INC information generation unit 33 performs an OR operation on the detection signal of the 25th light receiving element 70, the detection signal of the 25th light receiving element 70, and the detection signal of the 30th light receiving element 70, for example. An incremental signal may be generated.

  As described above, the INC information generation unit 33 is based on the detection signals of the light receiving elements 70 corresponding to the positions which are at least two detection signals of the plurality of detection signals and shifted by the pattern pitch D2 from each other. Generate information.

  As described above, in the encoder 1 according to the present embodiment, the scale 6 is a pattern indicating the position information of the driven body, and the absolute bit 61 and the incremental bit 62 are detected in the direction in which the position information is detected. Patterns 60 are alternately arranged at a predetermined pitch (for example, pattern pitch D2) in the direction of movement of the driving body. Here, the absolute bit 61 indicates position information as an absolute position based on a combination of a logic “0” state (first state) and a logic “1” state (second state). For example, a logic “0” state (first state) is indicated. The sensor unit 9 detects the pattern 60 of the scale 6 and outputs an output signal indicating a logic “0” state and a logic “1” state corresponding to the detected pattern 60. Based on the output signal (for example, the data string X1) output from the sensor unit 9, the signal generation unit 3 and the absolute position information (ABS information) corresponding to the absolute bit 61 and the incremental information ( INC information). The position detection unit 4 detects the position information of the driven body based on the absolute position information and the incremental information generated by the signal generation unit 3.

  Thereby, the encoder 1 in the present embodiment can generate both the absolute position information and the incremental information by one track in the scale 6. Therefore, for example, the encoder 1 in this embodiment does not need to have two tracks of an absolute track and an incremental track on the scale 6. In this case, the encoder 1 detects the absolute track detection signal and the incremental track detection signal. Therefore, it is not necessary to arrange the light receiving element 70 so as to be within the standard. For this reason, the encoder 1 according to the present embodiment can reduce the limitation on the mounting accuracy of the sensor unit 9, and thus, for example, reduces a decrease in detection accuracy of position information due to a shift in the mounting position of the sensor unit 9. can do. Therefore, the encoder 1 in the present embodiment can detect position information with high accuracy.

In addition, since the encoder 1 according to the present embodiment can generate both the absolute position information and the incremental information by one track in the scale 6, the light receiving element 70 can be shared. That is, the configuration of the encoder 1 in the present embodiment can be simplified.
Thus, the encoder 1 in this embodiment can detect position information with high accuracy with a simple configuration.

In the present embodiment, the sensor unit 9 includes a plurality of light receiving elements arranged at a pitch equal to or less than a half of a predetermined pitch (eg, pattern pitch D2) in the detection direction (eg, X-axis direction). 70. The sensor unit 9 outputs a plurality of detection signals obtained by detecting the pattern 60 by the plurality of light receiving elements 70 as output signals. And the signal generation part 3 produces | generates incremental information based on the at least 2 detection signal of several detection signals. Here, the at least two detection signals are detection signals detected by the light receiving element 70 corresponding to positions shifted by an integral multiple of a predetermined pitch (pattern pitch D2).
Thereby, the signal generation unit 3 can appropriately generate the incremental information from one track. Therefore, the encoder 1 in the present embodiment can detect position information with high accuracy based on appropriately generated incremental information.

In the present embodiment, the signal generation unit 3 generates an incremental signal based on a predetermined logical operation (for example, logical sum operation) of at least two detection signals.
Thereby, the signal generation unit 3 can generate incremental information with a simple configuration. Therefore, the encoder 1 in this embodiment can detect position information with high accuracy with a simple configuration.

In the present embodiment, at least two detection signals are detection signals detected by the light receiving element 70 corresponding to positions shifted by a predetermined pitch (pattern pitch D2).
Thereby, the signal generation unit 3 can appropriately generate the incremental information from one track.

In the present embodiment, the signal generation unit 3 determines the detection signal corresponding to the absolute bit 61 among the plurality of detection signals based on the likelihood calculated based on the plurality of detection signals. It has. In addition, the bit determination unit 31 determines a detection signal corresponding to the incremental bit 62 among the plurality of detection signals based on the detected signal corresponding to the determined absolute bit 61.
Thereby, the signal generation part 3 can generate | occur | produce the absolute position information and incremental information correctly by a simple means. Therefore, the encoder 1 in the present embodiment can detect position information with high accuracy.

In this embodiment, the absolute bit 61 and the incremental bit 62 have the same width in the detection direction (X-axis direction), and the width in the detection direction is a half width of a predetermined pitch (pattern pitch D2). (D1).
Thereby, since the absolute bit 61 and the incremental bit 62 are formed by the equal width D1, the signal generation unit 3 can accurately generate the absolute position information and the incremental information by a simple means.

[Second Embodiment]
Next, the encoder 1a in the second embodiment will be described.
FIG. 6 is a block diagram showing the encoder 1a according to the present embodiment.
In this figure, the same components as those in FIG. 2 are denoted by the same reference numerals, and the description thereof is omitted.
The encoder 1a in the second embodiment differs from the first embodiment in that it generates two types of incremental information of A phase and B phase.
In the following, differences from the first embodiment of the encoder 1a according to the second embodiment will be described.

  In FIG. 6, the encoder 1a includes a scale 6, a sensor unit 9a, and a signal processing unit 8a.

  The sensor unit 9a (detection head) includes the light source unit 2 and the line sensor unit 7a, and is arranged so as to maintain a predetermined distance from the scale 6. At least the light source unit 2 and the line sensor unit 7a of the sensor unit 9a are integrally supported by a support member (in this example, the detection substrate 5) of the sensor unit 9a. The scale 6 and the sensor unit 9a move relatively in the movement direction (X-axis direction).

The line sensor unit 7a includes, for example, two line sensors (sensor array 71 and sensor array 72) in which a plurality of light receiving elements 70 (detection elements) are arranged in a line shape in the detection direction (X-axis direction). . That is, the line sensor unit 7a detects the pattern 60 and outputs the first output signal (data string X11), and detects the pattern 60 and the second output. And a sensor array 72 (second detection element group) that outputs a signal (data string X12). The sensor array 72 is disposed at a position displaced from the sensor array 71 by a quarter of the pattern pitch D2 (width D4 in FIG. 6) in the detection direction (X-axis direction). That is, the light receiving element 70 of the sensor array 71 and the light receiving element 70 of the sensor array 72 are arranged so as to be shifted by a quarter (width D4) of the pattern pitch D2.
As described above, the line sensor unit 7a detects the pattern 60, and the first output signal (data string X11) and the second output signal having a predetermined phase difference (eg, 90 degrees) from the first output signal. An output signal (data string X11) is output as an output signal.

  Here, the plurality of light receiving elements 70 included in the sensor array 71 and the sensor array 72 are arranged in a detection direction (X-axis direction) with a pitch equal to or less than a half width D1 of the pattern pitch D2. For example, five light receiving elements 70 are arranged at a pattern pitch D2 so that the sensor pitch D3 is 4 μm. Further, the sensor array 71 and the sensor array 72 include, for example, 50 light receiving elements 70 (for 10 pattern pitches D2).

  The signal processing unit 8a performs irradiation control of the light source unit 2, and detects position information of the scale 6 in the movement direction (X-axis direction) based on output signals (data strings X11 and X12) output from the line sensor unit 7a. The detected position information (eg, position x) is output. The signal processing unit 8a includes a signal generation unit 3a, a position detection unit 4a, and a driver unit 81.

The signal generation unit 3 a generates absolute position information (ABS information) corresponding to the absolute bit 61 based on an output signal (for example, the data string X11) output from the sensor unit 9. Further, the signal generation unit 3 a generates first incremental information (A phase signal) based on the first output signal (data string X11) output from the sensor unit 9 and is output from the sensor unit 9. Second incremental information (phase B signal) is generated based on the second output signal (data string X12). The signal generation unit 3a outputs the generated incremental information (A phase signal and B phase signal) to the position detection unit 4a.
Here, the A-phase signal and the B-phase signal are incremental information that is 90 degrees out of phase with each other. The signal generation unit 3a generates the A phase signal and the B phase signal by the same method as the signal generation unit 3 in the first embodiment described above.

Further, the signal generation unit 3a calculates the likelihood based on, for example, the output signal (data sequence X11) output from the sensor unit 9, and based on the calculated likelihood, the absolute bit 61 in the data sequence X11. And an output signal corresponding to each of the incremental bits 62 is determined. Here, the signal generation unit 3a determines an output signal corresponding to each of the absolute bit 61 and the incremental bit 62 by the same processing as in the first embodiment described above. The signal generation unit 3a generates absolute position information (for example, a 10-bit code) based on the output signal corresponding to the absolute bit 61. The signal generation unit 3a outputs the generated absolute position information to the position detection unit 4a.
The signal generation unit 3a includes a bit determination unit 31, an ABS information generation unit 32, and an INC information generation unit 33a.

  The INC information generation unit 33a generates first incremental information (A-phase signal) based on the first output signal (data string X11) as described above, and generates the second output signal (data string X12). Based on this, second incremental information (phase B signal) is generated. The INC information generation unit 33a outputs the generated incremental information (A phase signal and B phase signal) to the position detection unit 4a.

  The position detection unit 4a is driven based on the absolute position information (ABS information) generated by the signal generation unit 3a, the first incremental information (A phase signal), and the second incremental information (B phase signal). Detect body position information. The position detector 4a outputs the detected position information to the outside of the encoder 1. The position detection unit 4a includes an absolute address processing unit 41, an interpolation processing unit 42a, and a synthesis processing unit 43.

  The interpolation processing unit 42a performs interpolation processing based on the incremental information (A phase signal and B phase signal) output from the signal generation unit 3a (INC information generation unit 33a), and performs interpolation data (relative position information). ) Is generated. Here, the interpolation processing unit 42a obtains two types of incremental information (A-phase signal and B-phase signal) that are 90 degrees out of phase, thereby performing a segmentation process, which will be described later, and performing an interpolation process with high resolution. Run. The interpolation processing unit 42 a outputs the generated interpolation data to the synthesis processing unit 43.

FIG. 7 is a diagram showing an example of the incremental information subdivision process in the present embodiment.
First, the interpolation processing unit 42a acquires incremental information (A phase signal) and incremental information (B phase signal) as indicated by the waveform W5 and the waveform W6 in FIG. 7 from the INC information generation unit 33a. The interpolation processing unit 42a generates a pulse at the rising edge and the falling edge of each of the A-phase signal (waveform W5) and the B-phase signal (waveform W6), as shown by the waveform W7 in FIG. A multiplied count pulse signal (PS1) is generated. The quadruple count pulse signal (PS1) is a count pulse signal multiplied by four with respect to the A-phase signal or the B-phase signal. The quadruple counting pulse signal (PS1) is generated with a pulse width that is sufficiently shorter than the half cycle of the A-phase signal and the B-phase signal.

  Further, the interpolation processing unit 42a further generates a quadruple counting pulse signal (PS2) that rises with a pulse width equal to the pulse at the falling edge of the quadruple counting pulse signal (PS1) (waveform W8 in FIG. 7). ). Similarly, the interpolation processing unit 42a generates a quadruple counting pulse signal (PS3) that rises with a pulse width equal to the pulse at the falling edge of the quadruple counting pulse signal (PS2) (waveform W9 in FIG. 7). . The interpolation processing unit 42a generates an 8-times counting pulse signal as shown by a waveform W10 in FIG. 7 based on the 4-times counting pulse signal (PS1) and the 4-times counting pulse signal (PS3).

  As described above, the interpolation processing unit 42a executes the subdivision process by generating the 8-fold count pulse signal (waveform W10) based on the incremental information (A phase signal) and the incremental information (B phase signal). The interpolation processing unit 42a performs an interpolation process based on the generated 8-times counting pulse signal. Thereby, the interpolation processing unit 42a can determine the moving direction of the driven body and obtain high resolution.

  As described above, in the encoder 1a according to the present embodiment, the sensor unit 9a detects the pattern 60, the first output signal (eg, the data string X11), the first output signal, and a predetermined position. A second output signal (eg, data string X12) having a phase difference (eg, 90 degree phase difference) is output as an output signal. The signal generation unit 3a generates first incremental information (A-phase signal) based on the first output signal (for example, the data string X11) output from the sensor unit 9a, and is output from the sensor unit 9a. Second incremental information (phase B signal) is generated based on the second output signal (eg, data string X12). The position detection unit 4a is based on the absolute position information (ABS information) generated by the signal generation unit 3a, the first incremental information (A phase signal), and the second incremental information (B phase signal). Detect information.

  As a result, the subdivision processing can be performed based on the first incremental information (A-phase signal) and the second incremental information (B-phase signal). Therefore, the encoder 1a in this embodiment is the same as that in the first embodiment. Compared with this, position information with higher resolution can be detected. Therefore, the encoder 1a in this embodiment can detect position information with high accuracy. In addition, the encoder 1a in the present embodiment can detect the moving direction of the driven body as position information by using the first incremental information (A phase signal) and the second incremental information (B phase signal). it can.

In the present embodiment, the sensor unit 9a detects the pattern 60 and outputs a first output signal (for example, the data string X11), and the sensor 60 detects the pattern 60 and outputs a second output signal ( For example, a sensor array 72 that outputs a data string X12) is provided. Here, the light receiving element 70 of the sensor array 72 is disposed at a position displaced from the sensor array 71 by a quarter of the pattern pitch D2 (width D4 in FIG. 6) in the detection direction (X-axis direction).
Thereby, the encoder 1a in the present embodiment can accurately generate the first incremental information (A-phase signal) and the second incremental information (B-phase signal) having a phase difference of 90 degrees from each other with a simple configuration. it can.

[Third Embodiment]
Next, the encoder 1b in the third embodiment will be described.
FIG. 8 is a block diagram showing the encoder 1b according to the present embodiment.
In this figure, the same components as those in FIG. 6 are denoted by the same reference numerals, and the description thereof is omitted.
The encoder 1b in the third embodiment is different from the second embodiment in that two types of incremental information of A phase and B phase are generated by one line sensor.
In the following, differences from the second embodiment of the encoder 1b in the third embodiment will be described.

  In FIG. 8, the encoder 1b includes a scale 6, a sensor unit 9b, and a signal processing unit 8a.

  The sensor unit 9b (detection head) includes the light source unit 2 and the line sensor unit 7b, and is arranged so as to maintain a predetermined distance from the scale 6. At least the light source unit 2 and the line sensor unit 7b of the sensor unit 9b are integrally supported by a support member (in this example, the detection substrate 5) of the sensor unit 9b. The scale 6 and the sensor unit 9b move relatively in the movement direction (X-axis direction).

The line sensor unit 7b includes, for example, one line sensor in which a plurality of light receiving elements 70 (detection elements) are arranged in a line shape in the detection direction (X-axis direction).
Here, the plurality of light receiving elements 70 are arranged at a pitch of a width D6 that is a quarter of the pattern pitch D5 in the detection direction (X-axis direction). For example, four light receiving elements 70 are arranged at a pattern pitch D5 so that the sensor pitch D6 is 5 μm.

As described above, the line sensor unit 7b includes a plurality of light receiving elements 70 shifted by the sensor pitch D6 as the sensor array 71a and the sensor array 72b. For example, the line sensor unit 7b includes 50 light receiving elements 70 (10 patterns having a pattern pitch D5). Min). That is, the line sensor unit 7b detects the pattern 60 and outputs a first output signal (data string X11), and detects the pattern 60 and the second output. And a sensor array 72a (second detection element group) that outputs a signal (data string X12).
The sensor array 72a is arranged at a position displaced from the sensor array 71a by a quarter of the pattern pitch D2 (width D6 in FIG. 8) in the detection direction (X-axis direction). That is, the light receiving elements 70 of the sensor array 71a and the light receiving elements 70 of the sensor array 72a are arranged so as to be shifted by a quarter (width D6) of the pattern pitch D2.
As described above, the line sensor unit 7b detects the pattern 60, and the first output signal (data string X11) and the second output having a predetermined phase difference (eg, 90 degrees) from the first output signal. An output signal (data string X11) is output as an output signal.

  In the present embodiment, the signal processing unit 8a is the same as that of the second embodiment, and thus the description thereof is omitted here.

As described above, in the encoder 1b according to the present embodiment, the plurality of light receiving elements 70 are arranged at a pitch of the width D6 that is a quarter of the pattern pitch D5 in the detection direction (X-axis direction). That is, the line sensor unit 7b detects the pattern 60 by the sensor array 71a (first detection element group) that detects the pattern 60 and outputs the first output signal (data string X11) by one line sensor. And a sensor array 72a (second detection element group) that outputs a second output signal (data string X12).
Thereby, the encoder 1b in this embodiment can simplify and save space in the configuration of the line sensor unit 7b. Therefore, the encoder 1b in the present embodiment can detect the position information with high accuracy with a simple configuration as in the second embodiment.

[Fourth Embodiment]
Next, an embodiment in which the encoder 1 (1a, 1b) in each of the above embodiments is applied to a drive device will be described.
FIG. 9 is a schematic block diagram showing the configuration of the driving apparatus 100 in the present embodiment.
The present embodiment is a drive device 100 that drives a moving body using the encoder 1 (1a, 1b) in each of the above embodiments. In the present embodiment, a stage apparatus that drives the stage 10 as an example of a moving body will be described.

In FIG. 9, a driving device 100 (device) that is a stage device includes an encoder 1 (1a, 1b), a stage 10, a driving unit 11, and a control unit 12. 9, the same components as those in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted.
The encoder 1 (1a, 1b) includes a scale 6, a sensor unit 9 (9a, 9b), and a signal processing unit 8 (8a).

The stage 10 (driven body) is fixed to, for example, the scale 6 or the sensor unit 9 (9a, 9b) and is driven (moved) by the driving unit 11. That is, the stage 10 is connected to the scale 6 or the sensor unit 9 (9a, 9b).
The drive unit 11 relatively drives the stage 10 in the position detection direction on the scale 6.
The control unit 12 is connected to the signal processing unit 8 (8a) of the encoder 1 (1a, 1b) via the control signal line C1. The encoder 1 (1a, 1b) supplies the above-described position information to the control unit 12 via the control signal line C1.
The control unit 12 is connected to the drive unit 11 via the control signal line C2. The control unit 12 controls the drive unit 11 via the control signal line C2.

  The control unit 12 controls the drive unit 11 based on the position information of the stage 10 supplied from the encoder 1 (1a, 1b).

As described above, the driving apparatus 100 according to the present embodiment includes the encoder 1 (1a, 1b) and the stage 10 connected to the scale 6 or the sensor unit 9 (9a, 9b).
Since the encoder 1 (1a, 1b) can detect the position information of the scale 6 with high accuracy, the driving apparatus 100 according to the present embodiment can detect the position information of the stage 10 with high accuracy. Thereby, the drive device 100 in the present embodiment can control the position of the stage 10 with high accuracy.

The present invention is not limited to the above embodiments, and can be modified without departing from the spirit of the present invention.
In each of the above-described embodiments, the line sensor unit 7 (7a, 7b) has been described as including the light receiving elements 70 for 10 pattern pitches, but the present invention is not limited to this. For example, in order for the bit determination unit 31 to determine the absolute bit 61 based on the likelihood based on the above equation (3), at least three pattern pitches D2 (D5) are necessary. That is, the plurality of light receiving elements 70 may be the number of detection elements capable of detecting a detection range corresponding to at least three pitches of the pattern pitch D2 (D5).
Thereby, the encoder 1 (1a, 1b) can accurately determine the absolute bit 61 even when, for example, a shift occurs in the mounting position of the sensor unit 9 (9a, 9b).

  Further, in each of the above embodiments, the INC information generation unit 33 (33a) generates incremental information by performing an OR operation on the output signal of the sensor unit 9 (9a, 9b) and the two shift signals as an example. However, the present invention is not limited to this. For example, the INC information generation unit 33 (33a) may be configured to generate incremental information based on at least two detection signals among a plurality of detection signals output from the plurality of light receiving elements 70, or four or more detections. A form in which incremental information is generated based on the signal may be used. Moreover, although the INC information generation part 33 (33a) demonstrated the form which produces | generates incremental information based on the detection signal shifted by the integral multiple of the pattern pitch, according to the output signal corresponding to the absolute bit 61, it is integral multiple. A form in which the shift amount is changed may be used. That is, the INC information generation unit 33 (33a), for example, if the absolute bit 61 is continuous with the absolute bit 610 in a state indicating logic “0”, the pattern pitch is determined according to the number of consecutive “0”. The shift amount that is an integer multiple of may be changed. Thereby, INC information generation part 33 (33a) can generate incremental information efficiently.

  In each of the above embodiments, the form in which incremental information is generated as a data string has been described. However, the present invention is not limited to this, and any other form can be used as long as the information can be subjected to interpolation processing. Also good. For example, the incremental information may be a single signal (incremental signal or information for one cycle in which phase information can be acquired.

  In each of the above embodiments, the mode in which the incremental bit 62 is the pattern 60 indicating the logic “0” has been described. However, the present invention is not limited to this, and the incremental bit 62 indicates the logic “0”. The form which is the pattern 60 may be sufficient. In this case, the INC information generation unit 33 (33a) may generate incremental information based on a negative logical product operation (NAND operation) instead of a logical sum operation. Further, the waveform W2 in FIG. 3 which is the incremental information may be a logically inverted signal. In this case, the INC information generation unit 33 (33a) negates instead of the logical sum operation (or the negative logical product operation). Incremental information may be generated based on an OR operation (NOR operation) (or an AND operation (AND operation)).

  In each of the above-described embodiments, the first state is the logic “0” state and the second state is the logic “1” state. However, the present invention is not limited to this. . For example, the first state may be a logic “1” state, and the second state may be a logic “0” state. Moreover, although the dark part (non-reflective part) of the pattern 60 is set to logic “0” and the bright part (reflective part) is set to logic “1”, the dark part (non-reflective part) is set to logic “1”. The bright portion (reflecting portion) may be set to logic “0”.

In each of the above embodiments, the encoder 1 (1a, 1b) has been described as a reflective optical encoder, but may be applied to a transmissive optical encoder. The encoder 1 (1a, 1b) may be a magnetic encoder. In this case, the detection element may include a magnetic detection element such as a Hall element instead of the light receiving element 70.
In each of the above embodiments, the encoder 1 (1a, 1b) is a linear encoder using the scale 6. However, the encoder 1 (1a, 1b) is applied to a rotary encoder using a disk-type or fan-shaped code plate. May be.

  In the second and third embodiments, the sensor array 71 (71a) and the sensor array 72 (72a) are arranged at positions shifted by a quarter of the pattern pitch, and the INC information generating unit 33a Has described the mode of generating two types of incremental information of A phase and B phase, but is not limited to this. For example, the encoder 1a (1b) includes two light source units 2 arranged so that detection signals shifted by a quarter of the pattern pitch are output, and the two light source units 2 are alternately used to A phase and a B-phase incremental signal may be generated.

  Further, in the fourth embodiment, the form in which the encoder 1 (1a, 1b) is applied to the driving device 100 that drives the stage 10 in the moving direction (eg, one direction) has been described. However, the present invention is not limited to this form. It is not something. For example, the present invention may be applied to devices such as an XY moving stage, a three-dimensional measuring device, a motor device, a machine tool, a precision machine, a semiconductor chip mounter, and a stepper device.

  Further, in each of the above embodiments, each unit of the encoder 1 (1a, 1b) may be realized by dedicated hardware, and includes a memory and a CPU (central processing unit), and is programmed. It may be realized.

  The above-described encoder 1 (1a, 1b) has a computer system inside. The process of the encoder 1 (1a, 1b) described above is stored in a computer-readable recording medium in the form of a program, and the above process is performed by the computer reading and executing this program. Here, the computer-readable recording medium means a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like. Alternatively, the computer program may be distributed to the computer via a communication line, and the computer that has received the distribution may execute the program.

  DESCRIPTION OF SYMBOLS 1, 1a ... Encoder, 3 and 3a ... Signal generation part, 4 ... Position detection part, 6 ... Scale, 10 ... Stage, 31 ... Bit determination part, 60 ... Pattern, 61, 610, 611 ... Absolute bit, 62 ... Incremental bit, 7,7a, 7b ... Line sensor part, 9 ... Sensor part, 70 ... Light receiving element, 71,71a, 72,72a ... Sensor array, 11 ... Drive part, 100 ... Drive device

Claims (13)

A pattern indicating position information of the driven body, and an absolute bit indicating the position information as an absolute position based on a combination of the first state and the second state; and an incremental bit indicating the first state A code plate having a pattern alternately arranged at a predetermined pitch in the detection direction of the position information;
A sensor unit that detects the pattern of the code plate and outputs an output signal indicating the first state and the second state corresponding to the detected pattern;
A signal generation unit that generates absolute position information corresponding to the absolute bit and incremental information corresponding to the incremental bit based on the output signal output from the sensor unit;
An encoder comprising: a detection unit that detects position information of the driven body based on the absolute position information and the incremental information generated by the signal generation unit. The sensor unit is
A plurality of detection elements arranged at a pitch equal to or less than a half width of the predetermined pitch in the detection direction, and a plurality of detection signals obtained by detecting the pattern by each of the plurality of detection elements as the output signal; Output,
The signal generator is
The encoder according to claim 1, wherein the incremental information is generated based on at least two detection signals of the plurality of detection signals. The encoder according to claim 2, wherein the at least two detection signals are detection signals detected by the detection elements corresponding to positions shifted from each other by an integral multiple of the predetermined pitch. The signal generator is
The encoder according to claim 2 or 3, wherein the incremental information is generated based on a predetermined logical operation of the at least two detection signals. 5. The detection signal according to claim 2, wherein the at least two detection signals are detection signals detected by the detection elements corresponding to positions shifted from each other by the predetermined pitch. 6. Encoder. The signal generator is
The encoder according to claim 3, wherein the shift amount of the integral multiple is changed in accordance with the output signal corresponding to the absolute bit. The signal generator is
The determination unit for determining a detection signal corresponding to the absolute bit among the plurality of detection signals based on the likelihood calculated based on the plurality of detection signals. The encoder according to any one of 6. The determination unit
The encoder according to claim 7, wherein a detection signal corresponding to the incremental bit among the plurality of detection signals is determined based on a detection signal corresponding to the determined absolute bit. The encoder according to claim 7 or 8, wherein the plurality of detection elements are a number of detection elements capable of detecting a detection range of at least three pitches of the predetermined pitch. The absolute bit and the incremental bit are:
The width of the detection direction is equal, and the width of the detection direction is formed to be a half width of the predetermined pitch. The encoder according to item. The sensor unit is
Detecting the pattern, and outputting a first output signal and a second output signal having a predetermined phase difference from the first output signal as the output signal;
The signal generator is
First incremental information is generated based on the first output signal output from the sensor unit, and second incremental information is generated based on the second output signal output from the sensor unit. ,
The detector is
The position information is detected based on the absolute position information generated by the signal generation unit and the first incremental information and the second incremental information. The encoder according to any one of the above. The sensor unit is
A first detection element group for detecting the pattern and outputting the first output signal;
A second detection element group disposed at a position displaced from the first detection element group by a quarter of the predetermined pitch in the detection direction, and detecting the pattern and outputting the second output signal; ,
The encoder according to claim 11, comprising: The encoder according to any one of claims 1 to 12,
The driven body connected to the code plate or the sensor unit;
A drive device comprising:

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