JP5948759B2 - Encoder device and device - Google Patents

Description

  The present invention relates to an encoder device and an apparatus.

  An encoder device having a function of detecting a reference position (for example, an origin position) along with a function of detecting position information is known (see, for example, Patent Document 1). In such an encoder device, for example, an origin mark for detecting an origin position is arranged on a scale for detecting position information, in addition to a main signal track for detecting position information. This origin mark is irradiated with light from a light source such as a laser diode, and the origin position is determined by a signal generated based on the signal detected by the origin detection light receiving element (for example, the position of the vertex in the triangular wave signal). Is detected.

JP-A-1-207627

  Here, in the encoder apparatus, for example, there is a case where the current of the laser diode is modulated and the interpolation is performed (for example, a case of a wavelength modulation type encoder). In such a case, the encoder device uses the light from the laser diode whose current is modulated to detect the origin position, so the detected signal increases or decreases depending on the modulation signal, and the detection accuracy of the origin position decreases. There is a problem that there is.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide an encoder apparatus and apparatus capable of detecting a reference position with high accuracy.

In order to solve the above problem, an embodiment of the present invention provides a scale having a reference position pattern indicating a reference position and a position information pattern, a light source that irradiates light to the scale, and a modulation signal that modulates the light. A position information detector for detecting position information of the scale based on a position information signal obtained by detecting the position information pattern with modulated light modulated based on the modulated signal, and the modulated light A reference position light receiving unit that outputs a detection signal in which the reference position pattern is detected, and a reference position detection unit that detects the reference position based on the detection signal. The reference position detection unit includes the detection A binarization unit that binarizes a signal indicating the reference position generated based on a signal based on a predetermined threshold; and a correction signal generated based on the modulation signal. There are, change the threshold, and a correction section that corrects the displacement of the reference position caused by modulating the light, an encoder device, characterized in that it comprises a.
In one embodiment of the present invention, a scale having a reference position pattern indicating a reference position and a position information pattern, a light source that irradiates light to the scale, and a modulation unit that generates a modulation signal for modulating the light, A main signal light receiving unit that receives first light via the position information pattern among modulated light modulated based on the modulation signal and outputs a position information signal; and a modulation signal supplied from the modulation unit; A position information detector that detects position information of the scale based on the position information signal, and a reference position light receiver that receives second light through the reference position pattern of the modulated light and outputs a detection signal. and parts, based on the detection signal, and a reference position detector for detecting the reference position, the reference position detection unit, a signal indicative of the reference position that is generated based on the detection signal two The predetermined threshold value used Upon for reduction, and further comprising a correction unit that changes based on the correction signal generated based on the modulated signal, to correct the displacement of the reference position caused by modulating the light This is an encoder device.

  Moreover, one Embodiment of this invention is an apparatus provided with the encoder apparatus as described above, and the moving body connected to the detection head of the said scale or the said encoder apparatus.

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

It is a schematic diagram which shows the structure of the optical system of the encoder apparatus by 1st Embodiment. It is a figure which shows the structure of the index grating | lattice, scale, and light-receiving part in 1st Embodiment. It is a schematic block diagram which shows the encoder apparatus in 1st Embodiment. It is a schematic block diagram which shows the origin detection part in 1st Embodiment. It is a wave form diagram which shows operation | movement of the origin detection part in 1st Embodiment. It is a wave form diagram which shows the production | generation operation | movement of the origin signal Z_SIG in 1st Embodiment. It is a schematic block diagram which shows the encoder apparatus by 2nd Embodiment. It is a schematic block diagram which shows the origin detection part in 2nd Embodiment. It is a schematic block diagram which shows the structure of the drive device by 3rd Embodiment. It is a schematic block diagram which shows the modification of the origin detection part in 1st Embodiment.

  Hereinafter, an encoder device (position detection device) according to an embodiment of the present invention will be described with reference to the drawings.

[First Embodiment]
FIG. 1 is a schematic diagram showing the configuration of the optical system 4 of the encoder device 1 according to the first embodiment. FIG. 2 is a diagram illustrating the configuration of the index grating 5, the scale 6, and the light receiving unit 7.
The encoder device 1 is, for example, a wavelength modulation type diffraction interference type encoder, and position information (for example, movement of the scale 6) of the scale 6 moving in a predetermined movement direction (for example, one direction such as the X-axis direction). This is an optical encoder that detects a direction, a movement amount, a displacement, or the like. The encoder device 1 according to the first embodiment has a function of detecting a reference position (for example, the origin position PZ) of the scale 6. In order to describe the positional relationship of the encoder device 1 according to the present embodiment, in FIG. 1, the direction toward the lower side of the page is defined as the positive direction of the Y axis, and the right direction of the page is defined as the positive direction of the X axis. 2 is a diagram of the index grating 5, the scale 6, and the light receiving unit 7 as viewed from the light source unit 2 toward the irradiation direction (+ Y-axis direction).

In FIG. 1, the encoder device 1 includes a light source unit 2, a collimator lens 3, an optical system 4, a scale 6, a light receiving unit 7, and a signal processing unit 8. The optical system 4 includes a glass block 41 and an index grating 5.
The light source unit 2, the collimator lens 3, the glass block 41, the index grating 5, and the light receiving unit 7 correspond to the detection head unit 9 (detection head). The light source unit 2, the collimator lens 3, the glass block 41, the index grating 5, and the light receiving unit 7 are integrally supported by the detection head unit 9. Further, the detection head unit 9 and the scale 6 relatively move in the X-axis direction described above.

The light source unit 2 (light source) is, for example, a laser element that emits laser light, and emits coherent modulated light modulated by a modulation unit 81 (to be described later) of the signal processing unit 8. The light source unit 2 irradiates the scale 6 with light.
The collimator lens 3 receives the modulated light emitted from the light source unit 2 and deflects it into parallel light in the Y-axis direction. The collimator lens 3 irradiates the optical system 4 with the deflected parallel light.

The glass block 41 is an optical path length changing unit that changes the optical path length of at least part of the light emitted from the collimator lens 3. For example, the glass block 41 is disposed between the collimator lens 3 and the index grating 5 and transmits light emitted from the collimator lens 3. The glass block 41 has a predetermined refractive index N1, and has a predetermined thickness D in the traveling direction of the light emitted from the collimator lens 3.
Therefore, the optical path length of the light passing through the glass block 41 is longer than the optical path length of the light passing through the air, for example, according to the refractive index N (for example, the refractive index N1) and the thickness D. Become. That is, the glass block 41 can relatively change the optical path length of the light applied to the scale 6.

  The index grating 5 is, for example, a diffraction grating in which a grating pattern is formed, and is a transmission type diffraction grating having a diffraction pattern periodically formed along the X-axis direction. The index grating 5 is disposed between the collimator lens 3 and the scale 6, generates diffracted light based on incident light, and irradiates the generated diffracted light to the scale 6.

As shown in FIG. 2A, the index grating 5 is a position pattern slit 53 that is a diffraction grating pattern for detecting position information of the scale 6, and a slit pattern for detecting the origin position PZ. And an origin pattern 50. The origin pattern 50 has random pattern slits (51, 52) formed by a random pattern.
The random pattern slits (51, 52) are formed such that when the scale 6 is at the origin position PZ, the slits are arranged at positions corresponding to random patterns (61, 62) in the origin pattern 60 of the scale 6 described later. Has been.

The scale 6 is disposed between the index grating 5 and the light receiving unit 7, and moves relative to the light source unit 2, the glass block 41, the index grating 5, and the light receiving unit 7. Here, as an example, the detection head unit 9 (the light source unit 2, the glass block 41, the index grating 5, and the light receiving unit 7) is fixed, and the scale 6 moves in the movement direction (for example, the X-axis direction).
As shown in FIG. 2B, the scale 6 is a scale used for position detection, and a position pattern 63 (position information pattern) for detecting position information and a reference position ( As an example, a reference position pattern (origin pattern 60) indicating the origin position PZ) is included.

  The origin pattern 60 is a reference position pattern indicating the origin position PZ of the scale 6, and is formed so as to transmit the modulated light emitted from the light source unit 2 through the collimator lens 3. The origin pattern 60 includes random patterns (61, 62) on the left and right of the transmission part on the rectangle. As described above, when the scale 6 is at the origin position PZ, the random patterns (61, 62) include the random pattern slits (51, 52) of the index lattice 5 and the slits of the random patterns (61, 62). They are arranged to match.

The position pattern 63 is a pattern for detecting position information, and is formed so as to transmit the modulated light emitted from the light source unit 2 through the collimator lens 3. The position pattern 63 is a diffraction grating on which a diffraction pattern periodically formed along the moving direction (for example, the X-axis direction) of the scale 6 is formed.
The position pattern 63 emits interference light between the diffracted light that passes through the glass block 41 and the diffracted light that does not pass through the glass block 41 to the light receiving unit 7.

  The light receiving unit 7 is arranged with a light receiving surface facing the light source unit 2, receives modulated light emitted from the light source unit 2 through the collimator lens 3, the index grating 5, and the scale 6, and photoelectrically converted a signal (described later). Output position information signal and detection signal) to the signal processing unit 8. Further, as shown in FIG. 2C, the light receiving unit 7 outputs an origin light receiving unit 70 that outputs a detection signal obtained by detecting the origin pattern 60 using modulated light, and a position information signal obtained by detecting the position pattern 63 using modulated light. And a main signal light receiving unit 73 for output.

Origin light receiving unit 70 outputs the first signal Z _L and the second signal Z _R is a signal that transitions to a different signal level from each other with respect to the origin position PZ as a detection signal. The origin light receiving unit 70 has origin light receiving elements (71, 72). The origin light receiving elements (71, 72) are arranged at positions corresponding to the origin pattern 50 of the index grating 5.
The origin light receiving element 71 receives (detects) the light transmitted from the origin pattern 60 through the random pattern slit 51 by the modulated light emitted from the light source unit 2 and outputs the first signal Z _L (detection signal). Further, the origin light receiving element 72 receives (detects) the light transmitted from the origin pattern 60 through the random pattern slit 52 by the modulated light emitted from the light source unit 2 and outputs the second signal Z _R (detection signal). To do.
Note that the first signal Z _L sharply transitions to a different signal level with respect to the origin position PZ by the random pattern slit 51 and the random pattern 61 described above. Further, the second signal Z _R, the random pattern slit 52 and a random pattern 62 described above, the origin position PZ, sharply transitions to different signal levels.

  The main signal light receiving unit 73 outputs a position information signal whose signal level periodically changes (for example, changes in a sine wave shape) with respect to the moving direction (X-axis direction) of the scale 6. The main signal light receiving unit 73 includes main signal light receiving elements (73a, 73b). The main signal light receiving elements (73a, 73b) receive the above-described interference light emitted from different positions of the position pattern 63, and output a photoelectric conversion signal indicating the interference intensity of the interference light as a position information signal.

The signal processing unit 8 periodically modulates the modulated light emitted by the light source unit 2. Further, the signal processor 8, based on the above-mentioned detection signal receiving unit 7 outputs (first signal Z _L and the second signal Z _R), the signal processing for detecting the origin position PZ of the scale 6, the above-described Based on the position information signal, signal processing for detecting the position information of the scale 6 is executed. Details of the configuration of the signal processing unit 8 will be described later with reference to FIG.

Next, the configuration of the signal processing unit 8 in the present embodiment will be described.
FIG. 3 is a schematic block diagram showing the encoder device 1 in the present embodiment.
3, the same components as those in FIGS. 1 and 2 are denoted by the same reference numerals, and the description thereof is omitted. In FIG. 3, the optical system 4 has an origin optical system 42 and a main signal optical system 43. Here, the origin pattern 50 (random pattern slits (51, 52)) of the index grating 5 and the origin pattern 60 of the scale 6 correspond to the origin optical system 42. Further, the glass block 41, the position pattern slit 53 of the index grating 5, and the position pattern 63 of the scale 6 correspond to the main signal optical system 43.

In FIG. 3, the signal processing unit 8 includes a modulation unit 81, a drive unit 82, an interpolation circuit unit 83, and an origin detection unit 90.
The modulation unit 81 generates a modulation signal that periodically modulates the wavelength of light. That is, the modulation unit 81 generates a modulation signal that modulates the light applied to the scale 6 (on the position pattern 63 and the origin pattern 50). For example, the modulation unit 81 generates a modulation signal modulated in a sine wave shape. The modulation unit 81 supplies the generated modulation signal to the drive unit 82, the interpolation circuit unit 83, and the origin detection unit 90.

  The drive unit 82 varies the current supplied to the light source unit 2 in accordance with the modulation signal supplied from the modulation unit 81. Here, when the current supplied to the light source unit 2 is changed, the light source unit 2 changes (changes) the wavelength and light amount of the irradiation light.

The interpolation circuit unit 83 (position information detection unit) detects the position information of the scale 6 based on the position information signal in which the position pattern 63 is detected by the modulated light modulated based on the modulation signal. That is, the interpolation circuit unit 83 is an encoding circuit that performs an interpolation process based on the position information signal output from the main signal light receiving unit 73. The position information signal output from the main signal light receiving unit 73 is superimposed with a modulation frequency component due to a change in the amount of modulated light. Therefore, the interpolation circuit unit 83 performs an interpolation process based on, for example, the modulation signal supplied from the modulation unit 81 and the position information signal output from the main signal light receiving unit 73. The interpolation circuit unit 83 performs interpolation processing using a synchronous detection circuit using a modulation signal, and detects position information of the scale 6.
Here, the position information includes, for example, the moving direction, moving amount, or displacement of the scale 6. For example, the signal processing method of “US Pat. No. 6,639,686” can be used as the position information detection method by such an interpolation circuit unit 83.

The origin detection unit 90 (reference position detection unit) detects the origin position PZ of the scale 6 based on the detection signals (first signal Z _L and second signal Z _R ) output from the origin light receiving unit 70. As an example, the origin detection unit 90 generates and generates a binarized origin signal Z_SIG indicating the origin position PZ of the scale 6 based on the detection signals (first signal Z _L and second signal Z _R ). An origin signal Z_SIG is output. Further, the origin detection unit 90 based on the detection signal (first signal _{Z L} and the second signal _{Z R),} a position in the vicinity of the origin position PZ, origin valid signal Z_VALID indicating that the origin signal Z_SIG is valid And the generated origin valid signal Z_VALID is output.
The detection signal (first signal Z _L and the second signal Z _R), the modulation frequency component of the light amount variation of the modulated light is superimposed. Therefore, the origin detection unit 90 includes a modulation correction unit 93 (see FIG. 4 described later) that corrects a displacement caused by modulation of the detected origin position PZ. In the present embodiment, the modulation correction unit 93 of the origin detection unit 90 generates an origin by modulating light (by the modulated light) based on the correction signal generated based on the modulation signal supplied from the modulation unit 81. The displacement of the position PZ is corrected.

Next, the configuration of the origin detection unit 90 in the present embodiment will be described.
FIG. 4 is a schematic block diagram showing the origin detection unit 90 in the present embodiment.
In FIG. 4, the origin detection unit 90 includes a differential circuit unit 91, a comparator unit (92, 95), a modulation correction unit 93, and an addition circuit unit 94. Note that an embodiment in which the origin detection unit 90 according to the present embodiment changes the threshold voltage that is the reference voltage of the comparator unit 92 based on the modulation signal supplied from the modulation unit 81 will be described.

The adder circuit unit 94 is an inverting adder circuit having resistors R1 to R3 and an operational amplifier (operational amplifier) 87, for example. The adding circuit unit 94 adds the first signal Z _L and the second signal Z _R to generate an inverted signal (− (Z _L + Z _R )) and outputs the signal to the comparator unit 95.
Resistor R1, the inverting input terminal of the detection signal line and the operational amplifier 87 of the first signal Z _L - is connected between a ((minus)), resistor R2, the second signal Z _R of the detection signal line and an operational amplifier 87 It is connected between the inverting input terminal (−). The resistor R3 is connected between the output terminal of the operational amplifier 87 and the inverting input terminal (−) of the operational amplifier 87, and applies negative feedback to the operational amplifier 87. Note that the non-inverting input terminal (+ (plus)) of the operational amplifier 87 is grounded. Here, the resistors R1 to R3 have, for example, the same resistance value.

The comparator unit 95 is a comparator (comparator) that binarizes the signal (− (Z _L + Z _R )) generated by the addition circuit unit 94 based on a predetermined threshold voltage V _A. The comparator unit 95 generates an inverted signal obtained by binarizing the signal (− (Z _L + Z _R )), and outputs the generated inverted signal as the origin valid signal Z_VALID. The comparator unit 95 includes, for example, resistors (R6, R7) and an operational amplifier 88.

The operational amplifier 88 functions as a comparator, and the inverting input terminal (−) is connected to the output terminal of the operational amplifier 87, and the non-inverting input terminal (+) is connected to the node A via the resistor R6. Further, the operational amplifier 88 is connected to the output terminal and the non-inverting input terminal (+) via the resistor R7, and positive feedback is applied.
The resistors (R6, R7) add a hysteresis to the threshold voltage _VA generated by the resistors (R4, R5) in order to binarize the origin valid signal Z_VALID. The threshold voltage _{V A} is generated by resistance voltage division of resistors (R4, R5), for example, an output voltage level of the first signal _{Z L} and the second signal _{Z R} of the (+ V) and (-V) A potential indicating an intermediate value is set.

The differential circuit unit 91 is a differential amplifier circuit having resistors R8 to R11 and an operational amplifier 84, for example. The differential circuit unit 91 generates a signal (Z _R −Z _L ) obtained by subtracting the second signal Z _R from the first signal Z _L and outputs the signal to the comparator unit 92. The signal (Z _R −Z _L ) is a signal indicating the origin position of the scale 6 generated based on the detection signals (first signal Z _L and second signal Z _R ) of the origin light receiving unit 70. That is, the differential circuit section 91, the difference between the first signal _{Z L} and the second signal _{Z R,} generates a signal indicating the origin position PZ.

Resistor R8 to the inverting input terminal of the detection signal line and the operational amplifier 84 of the first signal Z _L (-) is connected between the resistor R9 has a non-inverting input of the detection signal line and the operational amplifier 84 of the second signal Z _R Connected to the terminal (+). The resistor R10 is connected between the output terminal of the operational amplifier 84 and the inverting input terminal (−) of the operational amplifier 84 and applies negative feedback to the operational amplifier 84. The non-inverting input terminal (+) of the operational amplifier 84 is grounded via the resistor R11. Here, the resistors R8 to R11 have, for example, the same resistance value.

When light source modulation is performed as in the present embodiment, the modulation frequency component due to the change in the light amount is also superimposed on the first signal Z _L , the second signal Z _R , and the signal (Z _R −Z _L ). Here, the modulation frequency component superimposed on the first signal Z _L , the second signal Z _R , or the signal (Z _R −Z _L ) is referred to as modulation noise. This modulation noise is a signal whose signal level varies with time at the same frequency as the light source modulation (substantially the same as the light source modulation).

  The modulation correction unit 93 (correction unit) is an inverting amplifier circuit including resistors (R14, R15) and an operational amplifier 86, for example. The modulation correction unit 93 corrects the displacement of the origin position PZ caused by modulating the light (by the modulated light). For example, the modulation correction unit 93 corrects the displacement of the origin position PZ caused by the change in the amount of light based on the modulation signal output from the modulation unit 81. In the present embodiment, the modulation correction unit 93 inverts and amplifies the modulation signal output from the modulation unit 81 to generate a correction signal, and supplies the generated correction signal as a threshold voltage (predetermined threshold) of the comparator unit 92. . That is, the modulation correction unit 93 changes the threshold value of the comparator unit 92 according to the generated correction signal. Thereby, the modulation correction unit 93 corrects the displacement of the origin position PZ caused by modulating the light (by the modulated light). That is, the modulation correction unit 93 corrects the displacement of the origin position PZ based on the correction signal generated based on the modulation signal. The displacement of the origin position PZ is a displacement caused by modulating light (by modulated light), and is a displacement caused by the above-described modulation noise.

The resistor R14 is connected between the signal line of the modulation signal and the inverting input terminal (−) of the operational amplifier 86, and the resistor R15 is connected between the output terminal of the operational amplifier 86 and the inverting input terminal (−) of the operational amplifier 86. Thus, negative feedback is applied to the operational amplifier 86. The resistance values (R ₁₄ and R ₁₅ ) of the resistors R14 and R15 are set to predetermined values so as to correct the displacement of the origin position PZ caused by the modulated light. Details of the resistance value R ₁₄ and the resistance value R ₁₅ will be described later.

The comparator unit 92 (binarization unit) is a comparator (comparator) that binarizes the signal (Z _R −Z _L ) generated by the differential circuit unit 91 based on a predetermined threshold value. That is, the comparator unit 92 generates a signal indicating the origin position PZ of the scale 6 generated based on the detection signals (first signal Z _L and second signal Z _R ) of the origin light receiving unit 70 with a predetermined threshold (correction signal). Binarization based on the voltage. The comparator unit 92 generates an inverted signal obtained by binarizing the signal (Z _R −Z _L ), and outputs the generated inverted signal as the origin signal Z_SIG. As described above, the predetermined threshold value used for binarization is changed by the modulation correction unit 93 according to the correction signal generated based on the modulation signal. Therefore, the comparator unit 92 outputs the origin signal Z_SIG in which the displacement of the origin position PZ caused by the modulated light is reduced.

The comparator unit 92 includes, for example, resistors (R12, R13) and an operational amplifier 85.
The operational amplifier 85 functions as a comparator, and the inverting input terminal (−) is connected to the output terminal of the operational amplifier 84, and the non-inverting input terminal (+) is connected to the output terminal of the operational amplifier 86 via the resistor R12. Further, the operational amplifier 85 is connected to the output terminal and the non-inverting input terminal (+) via the resistor R13 and is subjected to positive feedback. Here, the non-inverting input terminal of the operational amplifier 85 (+) and a node B, illustrating the voltage at node B as the voltage V _B.
The resistors (R12, R13) add hysteresis to a predetermined threshold (voltage of the correction signal) generated by the modulation correction unit 93 in order to binarize the origin signal Z_SIG. This hysteresis suppresses chattering from occurring in the origin signal Z_SIG that is the output of the comparator unit 92. Here, for example, the threshold voltage V _H to which hysteresis is added when the positive output voltage of the comparator unit 92 is the voltage _VOUT is expressed by the following equation (1).

_Here, the resistance value of _{R 12} is the resistance _{R12, R 13} is the resistance of resistor R13.
That is, when the scale 6 is moved in the + X-axis direction with respect to the detection head unit 9, when the signal (Z _R −Z _L ) reaches the voltage V _H , the origin signal Z_SIG is changed to the signal level H (High: High). ) To a signal level L (Low).

Next, resistance values of the resistor R14 and the resistor R15 will be described.
First, a change (fluctuation) in the light amount I of the modulated light emitted from the light source unit 2 modulated by the modulation unit 81 is expressed by Expression (2).

Here, A corresponds to the average value of light quantity, m corresponds to the modulation degree, and ω corresponds to the modulation angular frequency. _{Further, R 14} is the resistance value of the resistor _{R14, R 15} is the resistance of resistor R15.
The first signal Z _L0 and the second signal Z _R0 is the output of the origin light-receiving unit 70 in a case without the modulation noise described above, the first signal Z _L and the second signal Z _R in the case of including modulation noise , Represented by equations (3) and (4).

Further, the signal (Z _R −Z _L ) is expressed as the equation (5) by the equations (3) and (4).

From this equation (5), it can be seen that the signal (Z _R −Z _L ) when modulation noise is included is proportional to the signal (Z _R0 −Z _L0 ). Here, when the modulation noise is not included, the position where the origin signal Z_SIG which is the output of the comparator unit 92 is inverted is the threshold voltage V _H where the signal (Z _R0 −Z _L0 ) is expressed by the above-described equation (1). It is a point that becomes equal. Therefore, when (Z _R0 −Z _L0 ) = V _H , the following formula (6) is obtained.

The modulation correction unit 93 supplies a signal obtained by inverting and amplifying the modulation signal (V _S sinωt) to one end of the resistor R12 of the comparator unit 92 according to the ratio of the resistance values of the resistors R14 and R15. That is, the modulation correction unit 93 introduces a modulation signal to the origin detection unit 90 in order to correct the displacement (small deviation) of the origin position PZ. In this case, the voltage V _B the voltage at a Node B, represented by the following formula (7).

Based on the equations (6) and (7), the resistance values (R ₁₄ , R ₁₅ ) of the resistors R14 and R15 are set to satisfy the following equation (8).

That is, the resistance value R ₁₄ and the resistance value R ₁₅ are set so that the fluctuation (change) of the voltage V _B in the vicinity of the origin position PZ is included in the signal (Z _R −Z _L ) and becomes equal to the modulation noise. That is, the modulation correction unit 93 generates a correction signal that changes the threshold value of the comparator unit 92 so as to cancel the modulation noise included in the signal (Z _R −Z _L ).
Since the resistance value R ₁₄ and the resistance value R ₁₅ do not take negative values, the amplitude V _{S of the} modulation signal is a negative value. That is, the phase of the modulation signal supplied to the resistor R14 needs to be inverted with respect to the modulation signal for modulating the light source.

Next, the detection operation of the origin position PZ of the encoder device 1 in the present embodiment will be described.
FIG. 5 is a waveform diagram showing the operation of the origin detection unit 90 in the present embodiment.
In FIG. 5, the horizontal axis of each graph indicates the position X of the scale 6 in the movement direction (detection direction), and the vertical axis indicates the voltage. In addition, the waveforms shown in FIGS. 5A to 5F are, in order, the first signal Z _L , the second signal Z _R , the signal (− (Z _L + Z _R )), and the signal (Z _R − Z _L ), origin valid signal Z_VALID, and origin signal Z_SIG, respectively.
In the present embodiment, an example in which the scale 6 is moved in the + X-axis direction with respect to the detection head unit 9 will be described.

First, the detection signals (first signal Z _L , second signal Z _R ) output from the origin light receiving unit 70 will be described with reference to FIGS. 5 (a) and 5 (b).
When the scale 6 is moved in the + X-axis direction with respect to the detection head unit 9, the origin light receiving element 71 from the light source unit 2 that has transmitted the origin pattern 60 at the position P 1 where the random pattern 62 overlaps the origin light receiving element 71. The modulated light is received. In this case, at the position P1, the origin light-receiving element 71, and receives the modulated light, as shown in FIG. 5 (a), as a detection signal, for example, the high signal level of the first signal Z _L from a low signal level Transition.

When the scale 6 is further moved, the position of the scale 6 reaches the origin position PZ. At the origin position PZ, the end of the random pattern 61 overlaps with the origin light receiving element 71, and the modulated light from the light source unit 2 that has passed through the origin pattern 60 is reduced. Therefore, the origin light receiving element 71 uses, for example, a first signal as a detection signal. It shifts the signal Z _L from a high signal level to the low signal level (Figure 5 (a)).
Further, at the origin position PZ, the random pattern 62 overlaps the origin light receiving element 72, and the origin light receiving element 72 receives the modulated light from the light source unit 2 that has passed through the origin pattern 60. In this case, at the origin position PZ, the origin light-receiving element 72, and receives the modulated light, as shown in FIG. 5 (b), as a detection signal, for example, a high signal level of the second signal Z _R from a low signal level Transition to. In other words, the origin light-receiving unit 70 outputs the first signal Z _L and the second signal Z _R is a signal that transitions to a different signal level from each other with respect to the origin position PZ as a detection signal.

At the origin position PZ, the origin optical system 42 is in a state where the random pattern slits (51, 52) of the index grating 5 and the random pattern (61, 62) of the origin pattern 60 of the scale 6 coincide. Therefore, the first signal _{Z L} and the second signal _{Z R} is at the origin position PZ, transits the steep waveform.

When the scale 6 is further moved, the random pattern 61 reaches a position P2 where it overlaps with the origin light receiving element 72. At this position P2, the end of the random pattern 61 overlaps with the origin light receiving element 72, and the modulated light from the light source unit 2 that has passed through the origin pattern 60 is reduced. Therefore, the origin light receiving element 72 uses, for example, a second signal as a detection signal. It shifts the signal Z _R from a high signal level to the low signal level (Figure 5 (b)).

Next, the origin detection unit 90, based on the first signal _{Z L} and the second signal _{Z R} described above, the operation of generating an origin valid signal Z_VALID and origin signal Z will be described.

<Generation of origin valid signal Z_VALID>
First, the addition circuit unit 94 of the origin detection unit 90 adds the first signal Z _L and the second signal Z _R to generate an inverted signal (− (Z _L + Z _R )) and outputs it to the comparator unit 95. To do. As shown in FIG. 5C, the adder circuit unit 94 causes the signal (− (Z _L + Z _R )) to transition from a high signal level to a low signal level at the position P1, and from a low signal level to a high signal at the position P2. Transition to the level.

Next, the comparator unit 95 generates an inverted signal obtained by binarizing the signal (− (Z _L + Z _R )), and outputs the generated inverted signal as the origin valid signal Z_VALID. Note that the threshold value of the comparator unit 95 used in the binarization is a voltage ( _VA ) obtained by adding hysteresis to the threshold voltage _VA generated by the resistors (R4, R5) by the resistors (R6, R7). ± α). Thereby, as shown in FIG. 5E, the comparator unit 95 changes the signal from the level L to the signal level H at the position P1 and the signal from the signal level H to the signal level L at the position P2, as the origin valid signal. Output as Z_VALID.

  Here, the origin valid signal Z_VALID is a signal indicating a position near the origin position PZ of the scale 6 and is a signal indicating whether or not the origin signal Z_SIG is valid. The origin valid signal Z_VALID is, for example, a position near the origin position PZ, and transitions to the signal level H when the origin signal Z_SIG is valid. Further, the origin valid signal Z_VALID transitions to the signal level L when the origin signal Z_SIG is not in the vicinity of the origin position PZ and the origin signal Z_SIG is invalid.

  For example, when the position is in the vicinity of the origin position PZ, the light receiving unit 7 is a position close to the origin position PZ of the scale 6 in the position range in the movement direction (X direction) of the scale 6. It is a range from P1 to position P2 or a predetermined point in a range from position P1 to position P2.

<Generation of origin signal Z_SIG>
First, the differential circuit unit 91 of the origin detection unit 90 generates a signal (Z _R −Z _L ) obtained by subtracting the second signal Z _R from the first signal Z _L and outputs the signal to the comparator unit 92. As shown in FIG. 5D, the differential circuit unit 91 causes the signal (Z _R −Z _L ) to transition from a low signal level to a high signal level at the origin position PZ.

Next, the comparator unit 92 generates an inverted signal obtained by binarizing the signal (Z _R −Z _L ), and outputs the generated inverted signal as the origin signal Z_SIG. The comparator unit 92 (binarization unit) binarizes the signal (Z _R −Z _L ) generated by the differential circuit unit 91 based on a predetermined threshold (voltage of the correction signal). Here, as described above, the predetermined threshold value used for binarization is changed by the modulation correction unit 93 according to the correction signal generated based on the modulation signal. Therefore, the comparator unit 92 outputs the origin signal Z_SIG in which the displacement of the origin position PZ caused by the modulated light is reduced. As shown in FIG. 5E, the comparator unit 92 outputs a signal that causes the signal (Z _R −Z _L ) to transition from the signal level H to the signal level L at the origin position PZ as the origin signal Z_SIG.

Note that since the modulated light does not pass through the scale 6 when the position is not near the origin position PZ, the origin detection unit 90 can hardly receive light. Therefore, the signal level of the signal (Z _R −Z _L ) may fluctuate across a predetermined threshold due to noise such as disturbance. In such a case, the comparator unit 92 outputs an erroneous origin signal Z_SIG such as the signal S1 and the signal S2 in FIG. Therefore, the encoder device 1 detects the origin signal Z_SIG when it is in the vicinity of the origin position PZ based on the origin valid signal Z_VALID. Thereby, the encoder apparatus 1 can reduce the erroneous detection of the origin signal Z_SIG.

FIG. 6 is a waveform diagram showing an operation of generating the origin signal Z_SIG in the present embodiment.
FIG. 6A shows a waveform obtained by enlarging the vicinity of the origin position PZ of the scale 6 in the signal (Z _R −Z _L ) of FIG. Here, the waveform W0 indicates a signal (Z _R −Z _L ), and the waveform W0a indicates an enlarged waveform in a portion R1 in the vicinity of the origin position PZ of the signal (Z _R −Z _L ).
FIG. 6B shows the waveform of the origin signal Z_SIG corresponding to FIG.

As shown in the waveform W0 in FIG. 6A, the signal (Z _R −Z _L ) includes (superimposes) the above-described modulation noise NZ. The modulation noise component (ΔNZ) in the vicinity of the origin position PZ is (V _H msin ωt) as shown in the equation (6). When the slope of the displacement X of the scale 6 with respect to the signal (Z _R −Z _L ) in the vicinity of the origin position PZ is (dX / dV), as shown in the waveform W0 in the region R1 close to the threshold voltage V _H , (ΔX = V _H msinωtdX / dX) appears as variations in the origin position PZ.

That is, the conventional encoder device does not include the modulation correction unit 93. Therefore, in such an encoder device, when modulated light is used, a displacement of the origin position PZ caused by the modulated light occurs in the origin signal Z_SIG as shown by the waveform W2 and the waveform W3 in FIG. 6B. .
On the other hand, the encoder device 1 of the present embodiment changes the threshold voltage V _B according to the correction signal generated by the modulation correction unit 93. Therefore, as shown by the waveform W1 in FIG. 6B, the comparator 92 corrects the displacement of the origin position PZ caused by the modulated light and outputs a stable origin signal Z_SIG.

As described above, the encoder device 1 of the present embodiment has the origin pattern 50 and the position pattern 63 in which the scale 6 indicates the origin position PZ (reference position), and the modulation unit 81 has the position pattern 63 and the origin pattern 50. A modulation signal for modulating the light applied to the light is generated. The interpolation circuit unit 83 (position information detection unit) detects the position information of the scale 6 based on the position information signal in which the position pattern 63 is detected by the modulated light modulated based on the modulation signal. The origin light receiving unit 70 (reference position light receiving unit) outputs a detection signal (Z _R −Z _L ) in which the origin pattern 50 is detected by the modulated light. The origin detection unit 90 (reference position detection unit) detects the origin position PZ based on the detection signal (Z _R −Z _L ). Further, the origin detection unit 90 includes a modulation correction unit 93 that corrects the displacement of the origin position PZ caused by modulating light.

  Thereby, the encoder device 1 according to the present embodiment outputs the origin signal Z_SIG in which the modulation correction unit 93 corrects the displacement of the origin position PZ. The origin signal Z_SIG is a signal indicating the origin position PZ. That is, the modulation correction unit 93 can reduce the influence of the modulation noise of the origin signal Z_SIG. Therefore, the encoder device 1 according to the present embodiment can detect the origin position PZ with high accuracy.

In the present embodiment, the modulation correction unit 93 corrects the displacement of the origin position PZ caused by the change in the amount of light based on the modulation signal generated by the modulation unit 81.
As a result, the encoder device 1 according to the present embodiment corrects the displacement of the origin position PZ caused by the change in the amount of light based on the modulation signal, so that the origin position PZ can be detected with high accuracy.

In the present embodiment, the modulation correction unit 93 generates a correction signal based on the modulation signal generated by the modulation unit 81, and the displacement of the origin position PZ caused by modulating light based on the generated correction signal. Correct. That is, the modulation correction unit 93 corrects the displacement of the origin position PZ based on the correction signal generated based on the modulation signal generated by the modulation unit 81.
The modulation signal and modulation noise generated by the modulation unit 81 fluctuate (change) according to the amount of modulated light. For example, since the modulation signal generated by the modulation unit 81 fluctuates (changes) in synchronization with the modulation noise, the encoder device 1 according to the present embodiment performs the following based on the modulation signal (based on the modulation signal): The displacement of the origin position PZ can be corrected. In this case, since the modulation signal generated by the modulation unit 81 can be used, the encoder device 1 according to the present embodiment can detect the origin position PZ with high accuracy with a simple configuration.

In the present embodiment, the origin detection unit 90 outputs a signal (Z _R −Z _L ) indicating the origin position PZ generated based on the detection signals (first signal Z _L and second signal Z _R ) as a predetermined value. Comparator unit 92 (binarization unit) that binarizes based on the threshold value. The modulation correction unit 93 changes a predetermined threshold according to the correction signal.
In this case, the displacement of the origin position PZ can be corrected with a simple configuration in which the modulation correction unit 93 changes the predetermined threshold value of the comparator unit 92 (binarization unit). Therefore, the encoder device 1 according to the present embodiment can detect the origin position PZ with high accuracy with a simple configuration.

Further, in the present embodiment, the origin light-receiving unit 70 outputs the first signal Z _L and the second signal Z _R is a signal that transitions to a different signal level from each other with respect to the origin position PZ as a detection signal. Origin detection unit 90 includes the difference between the first signal _{Z L} and the second signal _{Z R,} the differential circuit section 91 that generates a signal _(Z R -Z _L) indicating the origin position PZ.
Thus, origin detection unit 90, the difference between the first signal _{Z L} and the second signal _{Z R} for generating an origin signal Z_SIG, it is possible to accurately detect the origin position PZ.

In the present embodiment, the modulation signal generated by the modulation unit 81 is a signal that modulates the wavelength of the light irradiated to the position pattern 63 and the origin pattern 50. Also, by modulating the wavelength of light, the modulation signal generated by the modulation unit 81 modulates the amount of light irradiated to the position pattern 63 and the origin pattern 50. That is, the modulation signal generated by the modulation unit 81 is a signal that modulates the wavelength of the light (modulated light) applied to the position pattern 63 and the origin pattern 50.
As a result, the position of the scale 6 can be detected using a wavelength modulation technique. Therefore, the encoder apparatus 1 according to the present embodiment can detect the origin position PZ with high accuracy even in a highly accurate wavelength modulation type encoder.

In the present embodiment, the resistance value R _{14 of} the resistor R ₁₄ , the resistance value R ₁₅ of the resistor R ₁₅ , and the amplitude V _{S of the} modulation signal are set so as to satisfy the relationship of Expression (8). That is, the resistance value R _{14 of} the resistor R ₁₄ , the resistance value R ₁₅ of the resistor R ₁₅ , and the amplitude V _{S of the} modulation signal are obtained by changing (changing) the voltage V _B near the origin position PZ as a signal (Z _R −Z _L ). And is set to be equal to the modulation noise.
Thereby, the origin detection unit 90 can detect an accurate origin position PZ.

[Second Embodiment]
Next, an encoder device 1a according to the second embodiment will be described.
In the present embodiment, an embodiment in which the encoder device 1a corrects the displacement of the origin position PZ caused by modulating the wavelength of light based on the signal detected by the light receiving unit 7 will be described.
In the present embodiment, the configurations of the light source unit 2, the collimator lens 3, the optical system 4, the index grating 5, the scale 6, and the light receiving unit 7 are the same as those in the first embodiment shown in FIGS.

FIG. 7 is a schematic block diagram showing the encoder device 1a in the present embodiment.
7, the same components as those in FIGS. 1 to 3 are denoted by the same reference numerals, and the description thereof is omitted. In FIG. 7, the configuration of the origin detection unit 90 a is different from the encoder device 1 in the first embodiment shown in FIG. 3, and the other configuration is the same as the encoder device 1.

In FIG. 7, the signal processing unit 8a includes a modulation unit 81, a drive unit 82, an interpolation circuit unit 83, and an origin detection unit 90a.
Unlike the origin detection unit 90 in the first embodiment, the origin detection unit 90a is not connected to the modulation signal output from the modulation unit 81.

FIG. 8 is a schematic block diagram showing the origin detection unit 90a in the present embodiment.
In FIG. 8, the origin detection unit 90 a includes a differential circuit unit 91, a comparator unit (92, 95), a modulation correction unit 93 a, and an addition circuit unit 94. Incidentally, origin detection unit 90a according to the present embodiment, on the basis of the detection signal output from the origin light-receiving portion 70 of the light receiving portion 7 (the first signal Z _L and the second signal Z _R), the reference voltage of the comparator unit 92 An embodiment for changing a certain threshold voltage will be described. Here, as an example, the modulation correction unit 93a changes the threshold voltage, which is the reference voltage of the comparator unit 92, based on the signal (− (Z _L + Z _R )) output from the addition circuit unit 94.
In FIG. 8, the same components as those in FIG. 4 are denoted by the same reference numerals, and the description thereof is omitted.

The modulation correction unit 93a (correction unit) is, for example, an inverting amplifier circuit including a capacitor C1, resistors (R14, R14a, R15), and an operational amplifier 86. The modulation correction unit 93a corrects the displacement of the origin position PZ caused by modulating light. In the present embodiment, the modulation correction unit 93 a inverts and amplifies the signal (− (Z _L + Z _R )) output from the addition circuit unit 94 to generate a correction signal, and the generated correction signal is used as a threshold value of the comparator unit 92. Supply as voltage (predetermined threshold). That is, the modulation correction unit 93a changes the threshold value of the comparator unit 92 according to the generated correction signal. Thereby, the modulation correction unit 93a corrects the displacement of the origin position PZ. For example, the modulation correction unit 93a is a detection signal (first signal Z _L and the second signal Z _R) based on the correction signal generated based on, for correcting the displacement of the origin position PZ. That is, the modulation correction unit 93a corrects the displacement of the origin position PZ based on the correction signal generated based on the signal detected by the modulated light (by receiving the modulated light). The displacement of the origin position PZ is a displacement caused by modulating light (by modulated light), and is a displacement caused by the above-described modulation noise.

The resistor R14 is connected between one end (node C) of the capacitor C1 and the inverting input terminal (−) of the operational amplifier 86, and the resistor R15 is connected between the output terminal of the operational amplifier 86 and the inverting input terminal (−) of the operational amplifier 86. Connected between them, negative feedback is applied to the operational amplifier 86. Note that the resistance values (R ₁₄ , R ₁₅ ) of the resistors R14 and R15 are set to predetermined values so as to correct the displacement of the origin position PZ. Details of the resistance value R ₁₄ and the resistance value R ₁₅ in the present embodiment will be described later.
One end of the capacitor C <b> 1 is connected to one end of the resistor R <b> 14, and the other end is connected to the output signal line of the adder circuit unit 94. The connection point between the capacitor C1 and the resistor R14 is grounded via R14a. Capacitors C1 and R14a form a low-frequency cut filter circuit, cut the DC component included in the signal (− (Z _L + Z _R )) that is the output of the adder circuit unit 94, and invert the AC component to the operational amplifier 86. Supply to the input terminal (-). That is, it functions to extract a modulation noise component contained in the inverting input terminal (−) of the operational amplifier 86 and the signal (− (Z _L + Z _R )) and supply it to the operational amplifier 86.

Next, resistance values of the resistor R14 and the resistor R15 will be described.
The output signal (− (Z _L + Z _R )) of the adding circuit unit 94 is expressed by the following equation (9).

Considering that the signal (− (Z _L + Z _R )) is a constant value in the vicinity of the origin position PZ, this constant value is set as the voltage V _d . Further, by cutting the DC component by the capacitors C1 and R14a, the voltage V _{C at the} node V is expressed by the following equation (10).
Here, the low frequency cut frequency f comprising a resistance _{R 14a} of the capacitance _{C 1} and the resistor R14a of the capacitor C1 is determined by _{(1 / (2πR 14a C 1} )), the electrostatic capacitance C of the capacitor C1 ₁ and the resistance value R _{14a of the} resistor R14a are set such that the DC component of the signal (− (Z _L + Z _R )) is cut, but the modulation angular frequency ω passes sufficiently.

Furthermore, by replacing _{V S} of the aforementioned formula (8) and (-Vm), the relational expression of the following equation (11) is obtained.

Thus, in this embodiment, the resistance value R ₁₄ and the resistance value R ₁₅ are set so as to satisfy the equation (11) instead of the equation (8). That is, as in the first embodiment, the resistance value R ₁₄ and the resistance value R ₁₅ are such that the fluctuation (change) of the voltage V _B in the vicinity of the origin position PZ is included in the signal (Z _R −Z _L ) and the modulation noise. Is set to be equal to That is, the modulation correction unit 93a generates a correction signal that changes the threshold value of the comparator unit 92 so as to cancel the modulation noise included in the signal (Z _R −Z _L ).

Next, the detection operation of the origin position PZ of the encoder device 1a in the present embodiment will be described.
The operation of generating the origin valid signal Z_VALID in the encoder device 1a is the same as that of the encoder device 1 in the first embodiment. The operation of generating the origin signal Z_SIG in the encoder device 1a is the same as that of the encoder device 1 in the first embodiment except for the operation of the modulation correction unit 93a.
Modulation correction unit 93a, as described above, to generate a correction signal based on a detection signal (first signal Z _L and the second signal Z _R), on the basis of the generated correction signal, binarization of the comparator unit 92 A correction signal for changing the threshold value used in the above is generated.

  As described above, the encoder device 1a according to the present embodiment includes the modulation correction unit 93a that corrects the displacement of the origin position PZ caused by modulating light. Thereby, the encoder device 1a according to the present embodiment outputs the origin signal Z_SIG in which the displacement of the origin position PZ is corrected by the modulation correction unit 93a. That is, the modulation correction unit 93 can reduce the influence of the modulation noise of the origin signal Z_SIG. Therefore, the encoder device 1a according to the present embodiment can detect the origin position PZ with high accuracy.

In the present embodiment, the modulation correction unit 93a changes the displacement of the origin position PZ based on a correction signal generated based on a signal detected by the light receiving unit 7 receiving the modulated light modulated by the modulation unit 81. to correct. In other words, the modulation correction unit 93a is a detection signal (first signal Z _L and the second signal Z _R) based on the correction signal generated based on, for correcting the displacement of the origin position PZ.
Detection signal origin light-receiving section 70 of the light receiving portion 7 has been detected (the first signal Z _L and the second signal Z _R) and the modulation noise varies (changes) according to the amount of modulated light. That is, the detection signal (first signal Z _L and the second signal Z _R), because synchronization with fluctuating (change), the encoder device 1 according to this embodiment, based on a modulation signal (modulated signal Based on this, the displacement of the origin position PZ can be corrected. In this case, since the modulation signal generated by the modulation unit 81 can be used, the encoder device 1 according to the present embodiment can detect the origin position PZ with high accuracy with a simple configuration.

[Third Embodiment]
Next, an embodiment in which the encoder device 1 (1a) 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 device 1 (1a) 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 drive device 100 (device) that is a stage device includes an encoder device 1 (1a), a stage 10, a drive unit 11, and a control unit 12. In this figure, the same components as those in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted.
The encoder device 1 (1a) includes a scale 6, a detection head unit 9, and a signal processing unit 8.

For example, the stage 10 (moving body) is fixed to the scale 6 or the detection head unit 9 and is driven (moved) by the driving unit 11. That is, the stage 10 is connected to the scale 6 or the detection head unit 9.
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 of the encoder device 1 (1a) via the control signal line L1. The encoder device 1 (1a) supplies the position information, the origin signal Z_SIG, and the origin valid signal Z_VALID described above to the control unit 12 via the control signal line L1.
The control unit 12 is connected to the drive unit 11 via the control signal line L2. The control unit 12 controls the drive unit 11 via the control signal line L2.

The control unit 12 controls the drive unit 11 based on the position information of the stage 10 and the origin position PZ supplied from the encoder device 1 (1a).
Based on the origin valid signal Z_VALID, the control unit 12 determines whether or not the position of the stage 10 is in the vicinity of the origin position PZ, and determines that the position is in the vicinity of the origin position PZ, based on the origin signal Z_SIG. The origin position PZ is detected.

As described above, the driving device 100 according to the present embodiment includes the encoder device 1 (1a) and the stage 10 connected to the scale 6 or the detection head unit 9.
Since the encoder device 1 (1a) can detect the origin position PZ with high accuracy, the drive device 100 according to the present embodiment can detect the origin position PZ 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 embodiments, the modulation correction unit 93 (93a) has been described as changing the threshold value of the comparator unit 92 to correct the displacement of the origin position PZ. However, the present invention is not limited to this. For example, the modulation correction unit 93b of the origin detection unit 90b shown in FIG. 10 includes a differential circuit unit 96 having resistors R16 to R19 and an operational amplifier 89 instead of changing the threshold value of the comparator unit 92. In this case, the modulation correction unit 93 b offsets the modulation noise included in the signal (Z _R −Z _L ) indicating the origin position PZ output from the differential circuit unit 91 based on the correction signal output from the operational amplifier 86. To correct. That is, the modulation correction unit 93b corrects the signal (Z _R −Z _L ) indicating the reference position generated based on the detection signals (first signal Z _L and second signal Z _R ) based on the correction signal. . Thereby, the modulation | alteration correction | amendment part 93b has an effect similar to said each embodiment.

Further, in each of the embodiments described above, the modulation unit 81 has been described in the form in which the light amount of the light source unit 2 is also modulated by modulating the wavelength. However, the modulation unit 81 may be configured to modulate only the light amount.
Further, in each of the embodiments described above, the mode in which the detection signals (the first signal Z _L and the second signal Z _R ) are used as an example of the signal detected by the modulated light (by receiving the modulated light) has been described. It is not limited to this. For example, the modulation correction unit 93a may be configured to correct the displacement of the origin position PZ based on the signal detected by the main signal light receiving unit 73 of the light receiving unit 7, or may be configured to include a light receiving unit for correction.

In each of the above embodiments, the detection head unit 9 has been described as not including the signal processing unit 8. However, the detection head unit 9 may include the signal processing unit 8.
In each of the above embodiments, the scale 6 is a linear scale. However, the scale 6 may be applied to a rotary encoder using a disk-type or fan-shaped scale 6. Each of the above embodiments may be applied to a reflective encoder or may be applied to a transmissive encoder.
In each of the above embodiments, the detection head unit 9 is fixed and the scale 6 moves in the displacement direction. However, the scale 6 may be fixed and the head unit 9 may move in the displacement direction.

  In the third embodiment, the embodiment in which the encoder device 1 (1a) is applied to the driving device 100 that drives the stage 10 in the moving direction (one direction) has been described. However, the present invention is not limited to this embodiment. Absent. 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.

  DESCRIPTION OF SYMBOLS 1, 1a ... Encoder apparatus, 6 ... Scale, 9 ... Detection head part, 10 ... Stage, 60 ... Origin pattern, 63 ... Position pattern, 70 ... Origin light-receiving part, 81 ... Modulation part, 83 ... Interpolation circuit part, 90 , 90a, 90b ... origin detection unit, 91 ... differential circuit unit, 92 ... comparator unit, 93, 93a, 93b ... modulation correction unit, 100 ... driving device

Claims (10)

A scale having a reference position pattern indicating a reference position and a position information pattern;
A light source for irradiating the scale with light;
A modulation unit for generating a modulation signal for modulating the light;
A position information detection unit that detects position information of the scale based on a position information signal in which the position information pattern is detected by modulated light modulated based on the modulation signal;
A reference position light receiving unit that outputs a detection signal obtained by detecting the reference position pattern by the modulated light; and
A reference position detector for detecting the reference position based on the detection signal;
With
The reference position detector is
A binarization unit that binarizes a signal indicating the reference position generated based on the detection signal based on a predetermined threshold;
Based on a correction signal generated based on the modulation signal, a correction unit that changes the threshold and corrects the displacement of the reference position caused by modulating the light;
An encoder device comprising: A scale having a reference position pattern indicating a reference position and a position information pattern;
A light source for irradiating the scale with light;
A modulation unit for generating a modulation signal for modulating the light;
A main signal light receiving unit that receives first light via the position information pattern among modulated light modulated based on the modulation signal, and outputs a position information signal;
A position information detection unit that detects position information of the scale based on the modulation signal and the position information signal supplied from the modulation unit;
A reference position light receiving unit that receives the second light through the reference position pattern of the modulated light and outputs a detection signal;
A reference position detector for detecting the reference position based on the detection signal;
With
The reference position detection unit changes a predetermined threshold used for binarizing a signal indicating the reference position generated based on the detection signal based on a correction signal generated based on the modulation signal. the encoder apparatus further comprising a correcting unit for correcting the displacement of the reference position caused by modulating the light. The encoder device according to claim 2, wherein the correction unit corrects a displacement of the reference position caused by a light amount change of the light based on the modulation signal. The correction unit is
The encoder apparatus according to any one of claims 1 to 3 , wherein a displacement of the reference position is corrected based on a correction signal generated based on a signal detected by the modulated light. . The reference position detector is
A signal indicative of the reference position that is generated based on the detection signal, comprises a binarization unit for binarizing based on said threshold value,
The correction unit is
The encoder apparatus according to claim 3 , wherein the threshold value is changed according to the correction signal. The correction unit is
The encoder apparatus according to claim 3 or 4 , wherein a signal indicating the reference position generated based on the detection signal is corrected based on the correction signal. The reference position light receiving unit is
A first signal and a second signal, which are signals that transition to different signal levels with respect to the reference position, are output as the detection signal;
The reference position detector is
The encoder apparatus according to any one of claims 1 to 6 , further comprising a differential circuit unit that generates a signal indicating the reference position based on a difference between the first signal and the second signal. . The modulated signal is
The encoder apparatus according to any one of claims 1 to 7, characterized in that the signal for modulating the light intensity of the light provided to said position information pattern and the reference position patterns. The modulated signal is
The encoder device according to any one of claims 1 to 8 , wherein the encoder device is a signal that modulates a wavelength of the light applied to the position information pattern and the reference position pattern. The encoder device according to any one of claims 1 to 9 ,
A moving body connected to the detection head of the scale or the encoder device;
A device comprising:

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