JP2003035569A - Optical encoder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical encoder with high accuracy by reducing the influence of waveform distortion. SOLUTION: A waveform calculating section 901 creates correction data, which corrects waveform distortion, by using sine wave voltage signals 181-481 with four phases having a phase difference of 90 degree being output from current/voltage conversion circuits 101-104 and registers the correction data in a memory means 701 beforehand. When detecting the angle, a correction value calculating means 115 creates lower corrected data, which is digital data of lower bits, by using the correction data, and an interpolating means 113 creates lower data. Finally, angle data created by combining upper data and the lower data is output from the optical encoder.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a function of detecting the angle of a rotating body and the position of a linear moving body, and is particularly used for semiconductor inspection equipment, manufacturing equipment, machine tools, etc. The present invention relates to an optical encoder used for realizing speed control.

[0002]

2. Description of the Related Art Optical encoders include optical rotary encoders and optical linear encoders. Of these, the optical rotary encoder will be described with reference to the drawings. FIG. 11 is a configuration diagram of a conventional optical encoder. A half cross section of a general optical encoder 999 according to the prior art on the side of a light emitting / receiving element is shown in FIG.

This is a hollow shaft 5 mounted on the case 1 via bearings 3 and 4, and a slit plate 6 having a slit for transmitting light at a constant period on the outer peripheral part mounted on the hollow shaft 5, An LED 2 which is a specific example of a light emitting element disposed inside the case 1 at a position where a slit of the slit plate 6 can be illuminated, a light receiving element 7 which is disposed so as to face the LED 2 with the slit plate 6 interposed therebetween, The light receiving element 7 and the electronic component 9 are mounted, and the circuit board 8 is attached to the case 1.

FIG. 12 is a block diagram of a light receiving element 7 of a conventional optical encoder. For example, the lower side of this figure is the center direction 201 of the encoder, and the upper side is the outer peripheral direction 202.
Is. Further, the left and right directions 203 and 204 are the slit plates 6
Rotation direction, that is, the circumferential direction. The shaded area in the light receiving element shown in FIG. 12 is the light receiving cells 11 to 16, 21 to 26, 31 to 36, 41 for detecting the light transmitted through the slit plate 6.
When the light reaches this region, a photoelectric current signal is generated by photoelectric conversion.

These light receiving cells 11-16, 21-2
6, 31 to 36, 41 to 46 are, for example, an A group 18 including six light receiving cells 11 to 16 on the lower left side and a B group 28 including six light receiving cells 21 to 26 on the lower right side in the figure. , A group C composed of six light-receiving cells 31 to 36 on the upper left side, and a group D composed of six light-receiving cells 41 to 46 on the upper right side.

[0006] For example, when the number of slits in the outer peripheral portion of the slit plate 6 of the optical encoder is 2 ^8, A
Pitch 51 of the respective light receiving cells in the group 18, B group 28, C group 38, D group 48 becomes a mechanical angle ^{(360/2 8)} °. On the other hand, as shown in FIG.
When 1 is 360 ° in electrical angle, for example, the phase difference 52 between the A group 18 and the B group 28 is (90 + 360 × α) °, and the phase difference 53 between the A group 18 and the C group 38 is (180 +360
× β) °, for example, the phase difference (52+
53) is (270 + 360 × γ) °. Where α,
β and γ are appropriate integers.

In FIG. 12, since α, β, and γ are set to "1", the phase difference 52 between the A group 18 and the B group 28 is 90.
The phase difference 53 between the A group 18 and the C group 38 is 180 °, and the phase difference between the A group 18 and the D group 48 is 270 °.

FIG. 13 shows a light receiving element including each light receiving cell array (A group 18, B group 28, C group 38, D group 48) of a conventional optical encoder and its peripheral circuit diagram. From this figure, each light receiving cell array (A group 18, B group 28, C group 3
8, the power source (Vcc) is connected to the cathode side of the D group 48), which is a reverse bias connection. These A group 18, B group 28, C group 38, and D group 48 are electrically connected in parallel.

To the anode side of the group A 18 of the light receiving cell array, a current-voltage converting resistor 19 and a microcomputer 100, which are one specific example of a current-voltage converting circuit, are connected, and the other end of the current-voltage converting resistor 19 is connected. Is grounded. Similarly, each of the light receiving cell groups of the B group 28, the C group 38, and the D group 48 has the same circuit configuration as that of the A group 18, and is connected to the current-voltage converting resistors 29, 39, 49 and the microcomputer 100. Cage, current-voltage conversion resistor 2
The other ends of 9, 39 and 49 are grounded.

Next, the operation of the optical encoder will be described. As shown in FIG. 11, the light beam from the LED 2 reaches the light receiving element 7 after passing through the slits arranged on the outer peripheral portion of the slit plate 6 for alternately transmitting and blocking light.
The light beam reaching the light receiving element 7 is converted into a photocurrent signal proportional to the light amount in each light receiving cell. This photocurrent signal is converted into a voltage signal by the current-voltage converting resistors 19, 29, 39 and 49, and then, for example, the microcomputer 10
Taken to zero.

FIG. 14 shows an ideal voltage signal waveform diagram taken in by the microcomputer 100. The vertical axis 500 in this figure represents the voltage value, and the horizontal axis 501 represents the rotation angle of the slit disk. The A-phase signal 181 is obtained by converting the photocurrent from the light receiving cell array A group 18 into a sine wave voltage signal. Similarly, B-phase signal 281, C-phase signal 381,
Each of the D-phase signals 481 is group B 2 of the light receiving cell array.
8, the photocurrent signals from the C group 38 and the D group 48 are converted into sine wave voltage signals. These sinusoidal voltage signals can be expressed by the following equations.

[0012]

[Equation 1]

Here, VA _A , VA _B , VA _C , VA _D
Is a light receiving cell array A group 18 or B group 2 of the light receiving element 7.
8, the current signals from the C group 38 and the D group 48 are signals that are converted into a sine wave voltage signal and taken into the microcomputer 100, where X is an offset 50 of the A, B, C and D phase signals, and Y is a signal. Amplitude 51 is shown. Further, for each signal, if a sine wave obtained when the slit plate 6 moves for one cycle (until it moves from one slit to the next adjacent slit) is defined as an electrical angle of 360 °, each signal has 90 degrees in four phases.
A phase difference signal will be obtained. θ represents the rotation angle of the encoder at a certain timing by an electrical angle, and the change of θ by 360 ° corresponds to the movement amount of one pitch of the slit.

From the sine wave voltage signal taken in by the microcomputer 100, for example, as shown in FIG. 13, the A / D conversion means 1 built in the microcomputer 100.
The offset removal calculation means 109 via 12 subtracts the basic offset X to remove the offset component. That is, VA _{A to} VA _D are as follows.

[0015]

[Equation 2]

The offset-removing sine wave digital data 122 from the offset-removing calculating means 109 is the interpolation means 1.
After being subjected to the interpolation multiplication processing in 13, the lower data 124 is obtained. Here, the interpolating means 113 performs, for example, the following calculation.

[0017]

[Equation 3]

This calculation process represents a process of electrically dividing a sine wave signal corresponding to one slit pitch.
On the other hand, the comparator 1 in the microcomputer 100
The binary signal 121, which is a square wave obtained via
The higher-order data 123 is obtained by counting with the counter means 111 in the microcomputer 100.

As described above, the upper data obtained by counting the number of slits and the lower data obtained by electrically dividing one sine wave are combined to obtain angle data to obtain high resolution and high accuracy. It is used as an optical rotary encoder.

[0020]

However, the angle detection accuracy of the optical rotary encoder is determined by the interpolation double precision of the lower data, and the interpolation double precision depends on the distortion of the waveform. The output signal from the current-voltage conversion circuit of the actual encoder will have a waveform distortion due to 1) optical encoder assembly error, 2) sensitivity variation of the light receiving element 7, 3) uneven illumination of the LED 2, etc. .

FIG. 15 is an actual voltage signal waveform diagram taken in by the microcomputer. 15, only the waveforms of VA C ₃₈₁ for simplicity of explanation are described as having a waveform distortion, in practice, are those having the waveform distortion in all signals. The analog voltage signal before being taken in by the microcomputer 100 is expressed by the following expression.

[0022]

[Equation 4]

Where ΔX_A, ΔX_B, ΔX_C, ΔX_D
Is the offset error of each signal 60, ΔY_A, ΔY_B, ΔY
_C, ΔY_DIs the amplitude error 61, Δθ of each signal_B, Δθ_C,
Δθ _DIs the phase difference error 62 of each signal. Wrong offset
The difference and the amplitude error of the reference offset X and the reference amplitude
The difference (error) from Y, and the phase difference error is 90
It is the difference (error) from °. Such an offset error
If the difference, amplitude error, and phase difference error increase, the interpolation
The problem that the error increases and the angle detection accuracy deteriorates
was there. In addition, such problems are caused by optical rotary
The encoder is not limited to optical encoders.
It can happen even in a coder.

The present invention is intended to solve the above-mentioned problems, and an object thereof is to provide a highly accurate optical encoder which reduces the influence of waveform distortion in the prior art.

[0025]

In order to solve the above-mentioned problems, the invention according to claim 1 is formed by dividing the light-receiving cells arranged on a two-dimensional plane into four groups by substantially orthogonal dead zones.
Group B, group C, group C, and group D, and four groups of light receiving cell arrays are arranged so that the photocurrent signals output from these four groups of light receiving cell arrays are periodic signals having different phases. A light-receiving element, a light-emitting element which is arranged at a position facing the light-receiving element and which emits irradiation light toward the light-receiving element, and a slit array for transmitting and blocking irradiation light from the light-emitting element. Slit plate having a track for use, a current-voltage conversion circuit for converting a sine-wave current signal output from each light-receiving cell array of the light-receiving element into a sine-wave voltage signal, and a sine-wave voltage signal output from the current-voltage conversion circuit The correction data generating means for generating and storing the correction data for correcting the waveform distortion is used, and the sine wave voltage signal output from the current-voltage conversion circuit is used to Higher-order data generation means for generating higher-order data, which is digital data of bits, and digital data of lower-order bits, using the correction data stored by the correction-data generation means in addition to the sine wave voltage signal output from the current-voltage conversion circuit. It is characterized in that lower data generating means for generating lower data, which is data, and angle data combining these upper data and lower data are output.

According to a second aspect of the present invention, in the optical encoder according to the first aspect, the correction data generating means A / D-converts the sine wave voltage signal output from the current-voltage conversion circuit. Outputs sine wave digital data A
The A / D conversion means, the waveform calculation means for calculating correction data including the amplitude correction data, the offset correction data and the phase difference correction data using the sine wave digital data from the A / D conversion means, and the waveform calculation means. Memory means for registering the calculated correction data.

According to a third aspect of the present invention, in the optical encoder according to the first or the second aspect, the higher-order data generating means binary-codes the sine wave voltage signal output from the current-voltage conversion circuit. Comparator means for converting into a binary signal and outputting the binary signal, and 2 calculated by the comparator means
Counter means for counting and generating upper data based on the value signal.

The invention according to claim 4 is the optical encoder according to any one of claims 1 to 3, wherein:
The lower data generation means includes A / D conversion means for A / D converting a sine wave voltage signal output from the current-voltage conversion circuit to output sine wave digital data, and a sine wave from the A / D conversion means. Using offset removal calculation means for removing offset component of wave digital data and outputting offset removal sine wave digital data, offset removal sine wave digital data from the offset removal calculation means and correction data from the correction data generation means Correction value calculation means for generating corrected lower-order data from which the amplitude error, offset error and phase difference error have been removed, and interpolation means for calculating lower-order data using the corrected lower-order data as digital data of lower-order bits. It is characterized by

According to a fifth aspect of the present invention, there is provided a light receiving cell array called A group, B group, C group and D group, which is formed by dividing the light receiving cells arranged on a two-dimensional plane into four groups by substantially insensitive zones. Light receiving elements in which the four groups of light receiving cell arrays are arranged such that the photocurrent signals output from the four groups of light receiving cell arrays are periodic signals having different phases, and are arranged at positions facing the light receiving elements. A light emitting element that emits irradiation light toward the light receiving element, a slit plate having a detection track formed of a slit row for transmitting and blocking the irradiation light from the light emitting element, and each light receiving element of the light receiving element. A current-voltage conversion circuit that converts a sine wave current signal output from the cell array into a sine wave voltage signal,
A differential operation circuit that outputs a differential sine wave voltage signal by making a difference between two phase sine wave voltage signals having a phase difference of 180 ° among the sine wave voltage signals output from the current-voltage conversion circuit;
Correction data generating means for generating and storing correction data for correcting waveform distortion using the differential sine wave voltage signal output from the differential operation circuit, and a differential sine wave voltage signal output from the differential operation circuit Upper data generation means for generating higher data which is digital data of higher bits using
Lower-order data generation means for generating lower-order data, which is digital data of lower-order bits, by using the correction data stored by the correction data generation means in addition to the differential sine wave voltage signal output from the differential operation circuit, and these. It is characterized by outputting angle data that is a combination of upper data and lower data.

According to a sixth aspect of the present invention, in the optical encoder according to the fifth aspect, the correction data generating means A / D converts the differential sine wave voltage signal output from the differential operation circuit. A / D converting means for outputting differential sine wave digital data and correction using the differential sine wave digital data from the A / D converting means, which is composed of amplitude correction data, offset correction data and phase difference correction data. It is characterized by comprising a waveform calculating means for calculating data and a memory means for registering the correction data calculated by the waveform calculating means.

The invention of claim 7 is the optical encoder according to claim 5 or 6, wherein the higher-order data generating means outputs the differential sine wave voltage signal output from the differential operation circuit. Comparator means for binarizing and outputting a binary signal, and 2 calculated by the comparator means
Counter means for counting and generating upper data based on the value signal.

The invention of claim 8 is the optical encoder according to any one of claims 5 to 7, wherein:
The lower-order data generation means includes A / D conversion means for A / D converting the differential sine wave voltage signal output from the differential operation circuit to output differential sine wave digital data, and the A / D conversion means.
Correction value calculating means for generating corrected lower-order data from which amplitude error, offset error and phase difference error are removed using the differential sine wave digital data from the D conversion means and the correction data from the correction data generating means; Interpolation means for calculating lower data that uses the corrected lower data as digital data of lower bits.

Further, the invention of claim 9 is the optical encoder according to any one of claims 5 to 8, wherein:
When calculating the correction data composed of the amplitude correction data, the offset correction data, and the phase difference correction data, n pieces of correction data are calculated by dividing the differential sine wave digital data in a predetermined section into n ranges, It is characterized in that data is written in n areas of the memory means.

The invention according to claim 10 is the optical encoder according to any one of claims 1 to 9, wherein the waveform calculating means is an external computer.

According to the invention of claim 11, in the optical encoder according to any one of claims 1 to 10, there are provided a normal detection mode for performing normal detection and a correction value calculation mode for performing correction value calculation. It is characterized in that a switching means for switching is provided.

According to a twelfth aspect of the present invention, in the optical encoder according to any one of the first to eleventh aspects, the slit plate is a disc having detection tracks arranged in a substantially circular shape. A slit-shaped slit plate, wherein the light-emitting element and the light-receiving element are arranged so as to face each other with the slit plate interposed therebetween, and the rotary encoder detects a shift amount of the rotating slit plate in the rotation direction. .

According to a thirteenth aspect of the present invention, in the optical encoder according to any one of the first to eleventh aspects, the slit plate has a substantially rectangular shape in which detection tracks are arranged in a substantially linear shape. The slit-shaped slit plate is a linear encoder that detects a shift amount in the linear direction by moving both the light-emitting element and the light-receiving element in the linear direction while facing each other along the fixed slit plate.

[0038]

With the above configuration, the waveform distortion (amplitude, offset, phase difference) is calculated by comparing the actual sine wave signal obtained from the light receiving element with the ideal sine wave signal, and the waveform distortion is obtained from the light receiving element. Corrected by removing the waveform distortion from the actual sine wave signal to obtain an ideal sine wave signal by program processing, and using this ideal sine wave signal, the angle detection accuracy and optical Improves the position detection accuracy of the linear encoder.

[0039]

BEST MODE FOR CARRYING OUT THE INVENTION [First Embodiment] An optical encoder according to the first embodiment of the first to fourth, eleventh and twelfth aspects of the present invention will be described. FIG. 1 is a block diagram of the optical encoder of the present embodiment, and FIG. 2 is a block diagram of the light receiving element of the optical encoder of the present embodiment. Regarding the structure of the optical encoder shown in FIGS. 1 and 2, the layout of the light receiving element 7, the photocurrent signal and the operation output from the light receiving element 7,
Since it is the same as the conventional example, detailed description will be omitted.

FIG. 3 is a block diagram of the optical encoder of this embodiment and its peripheral equipment. The microcomputer 100 has a switching means such as a DIP switch capable of switching between the correction value calculation mode and the normal detection mode. The correction value calculation mode is a mode when the correction value is calculated in advance before using the optical encoder or before factory shipment, and the normal detection mode is when the correction value calculation mode is used as a normal angle detection sensor after the correction value is acquired. Mode. The following will be described as being performed in the correction value calculation mode.

As the slit plate 6 rotates, the light receiving cell 11
16 to 21, 21 to 26, 31 to 36, and 41 to 46 output photocurrents, and four-phase sinusoidal current signals having different 90 ° phases are output. As shown in FIG. 3, these sinusoidal current signals are converted into sinusoidal voltage signals corresponding to 360 ° by moving one slit pitch (one cycle) by the current-voltage conversion circuits 101 to 104 composed of operational amplifiers. Signals 181,281,381,481 (see FIG. 14)
Is converted into the image data and is taken into the microcomputer 100. These sinusoidal voltage signals 181,281,381,4
81 has a phase difference of 90 ° in four phases.

However, as described in the problem to be solved by the invention, four-phase sinusoidal voltage signals 181, 281, 381, 4 taken into the microcomputer 100 are included.
81 is the offset error 60 (ΔX _A , ΔX _B , Δ
X _C , ΔX _D ), amplitude error 61 (ΔY _A , ΔY _B , ΔY
_C , ΔY _D ), phase difference error 62 (Δθ _B , Δθ _C , Δθ
_D ) is included, which is a major factor in the deterioration of accuracy (Fig. 1
5). Therefore, a correction value for removing the offset error, the amplitude error, and the phase difference error, which are the main factors of the waveform distortion, is acquired. First, the current-voltage conversion circuits 101 to 10
Four-phase sinusoidal voltage signal 18 with a phase difference of 90 ° in 4 phases
As shown in FIG. 3, the signals 1,281,381,481 are taken into the waveform calculation means 901 through the A / D conversion means 112 inside the optical encoder 999.

For example, the number of slits in the slit plate 6 is two.
^{In case of 8} pieces (256 pieces), 4 × 2 ⁸ pieces (1 piece per rotation)
024) sine waves are output. These are amplitude values (Y + ΔY _A1-A256 , Y + ΔY _B1-B256 ) due to influences of 1) assembly error of the optical encoder, 2) sensitivity variation of the light receiving element 7, 3) uneven illumination of the LED ₂ ,
Y + ΔY _{C1-C 256} , Y + ΔY _D1-D256 ),
Offset value (X + ΔX _A1-A256 , X + ΔX
_B1-B256 , X + ΔX _C1-C256 , X + ΔX
_D1-D256 ) and phase difference (90 ° + Δθ
_B1-B256 , 90 ° + Δθ _C1-C256 , 90 ° + Δθ _D1-D256 ) includes an error component.

Next, the 4 × data taken in by the waveform calculation means 901.
From 2 ⁸ sine waves, 4 × 2 ⁸ amplitude values, offset values and phase differences are calculated. Then, the amplitude error (ΔY
_A1-A256 , ΔY _B1-B256 , ΔY
_C1-C256 , ΔY _D1-D256 ), offset error (ΔX _{A1-A2 56} , ΔX _B1-B256 , ΔX
_C1-C256 , ΔX _D1-D256 ) is calculated. Similarly, a phase difference error (Δθ _B1-B256 , Δθ) _obtained by removing the reference phase difference 90 ° from the 3 × 2 ⁸ phase differences.
_C1-C256 and Δθ _D1-D256 ) are calculated.

These amplitude errors (ΔY _A1-A256 , Δ
Y _B1-B256 , ΔY _{C1-C2 56} , ΔY
_D1-D256 ), offset error (ΔX
_A1-A256 , ΔX _{B1- B256} , ΔX
_C1-C256 , ΔX _D1-D256 ) and phase difference error (Δθ _B1-B256 , Δθ _C1-C256 , Δθ
_D1-D256 ) average value is calculated, and the calculation result is
Amplitude average error (ΔY _{A_mean} , ΔY
_{B_m ean, ΔY C_mean, ΔY
D_mean} ), offset average error (ΔX
_{A_mean} , ΔX _{B_mean} , ΔX
_{C_mean, ΔX D_me an),} the phase difference mean error _{(Δθ B_mean, Δθ C_mean, Δθ} D
_{_Mean} ).

These amplitude average error, offset average error, and phase difference average error are stored in, for example, the memory means 701 as amplitude correction values (ΔY _{A_correct} , ΔY).
_{B_corre ct, ΔY C_correct, Δ}
Y _{D_correct} ), offset correction value (ΔX
_{A_correct} , ΔX _{B_correct} , Δ
_{X C_co} rrect, Δ
X _{D_correct} ), phase difference correction value (Δθ
_{B_corr ect, Δθ C_correct, Δ}
write as θ _{D — correct} ). Actually, they are written as amplitude correction data, offset correction data, and phase difference correction data which are digital data. Such processing is performed in the correction value calculation mode.

Next, the normal detection mode for normal angle detection will be described. In the normal detection mode, the microcomputer 100 performs the following processing. First, the acquisition of upper data will be described. As described in the conventional example, the sinusoidal voltage signals 181, 281, 381, 481 captured in the microcomputer 100 are, for example,
As shown in FIG. 3, a square wave binary signal 121 is passed through the comparator means 110 in the microcomputer 100.
Is converted to. Then, the binary signal 121 is counted by the counter means 111 in the microcomputer 100 to count the number of sine waves, and the count value represented as digital data is output as the upper data 122.

Next, the acquisition of lower data will be described. The sine wave voltage signals 181, 281, 381, 481 taken in the microcomputer 100 are converted into sine wave digital data via the A / D conversion means 112. Further, the basic offset X is divided by the offset removal calculation means 109 to obtain offset-removed sine wave digital data from which the offset component has been removed. The A / D conversion unit 112 described here is the same as the waveform calculation unit 90 described above.
It may be common to the A / D conversion means 112 connected to 1.

In general, the output offset removal sine wave digital data 123 of the offset removal calculation means 109 in the microcomputer 100 may be a signal of the following formula as digital data.

[0050]

[Equation 5]

Then, the correction value calculation means 115 in the microcomputer 100 reduces the influence of the waveform distortion by using the correction data composed of the amplitude correction data, the offset correction data and the phase difference correction data in the memory 701. And the corrected lower data 126, which is a digital signal representing the following signal, is generated.

[0052]

[Equation 6]

The interpolation means 113 uses this corrected lower data 12
6 is converted to lower bit digital data and lower data 124 is output. And the angle data 206 which combined the upper data 122 and the lower data 125 is output. As described above, the optical encoder according to the present embodiment combines the high-order data obtained by counting the number of slits and the correction low-order data obtained by electrically dividing one sine wave into a high-order data. An optical encoder with high resolution and high resolution is obtained.

The first embodiment has been described above. Although the optical encoder of this embodiment has been described as being a rotary encoder, as an embodiment according to claim 13 of the present invention, a substantially rectangular slit plate in which the detection tracks are arranged in a substantially straight line is provided. An optical linear encoder that is fixed and moves along the slit plate along the linear direction while the light emitting element and the light receiving element are opposed to each other to detect the amount of displacement in the linear direction. It may have a value calculation function. In this case as well, an optical encoder having high resolution and high accuracy can be provided as in the optical rotary encoder.

[Second Embodiment] Next, claim 5 of the present invention
The second embodiment according to 8 to 11, 12 will be described. FIG. 4 shows a block diagram of the optical encoder and its peripherals according to the second embodiment. In the present embodiment, in addition to the configuration of the first embodiment, current-voltage conversion circuits 101, 102,
Differential operation circuits 131 and 132 are connected to 103 and 104. Further, the means in the microcomputer 100 is slightly different due to such measures. Except for this, the structure of the encoder, the layout of the light receiving elements, and the operation of the light receiving elements are the same as those of the conventional example, and thus detailed description thereof will be omitted.

Next, the correction value calculation mode of this embodiment will be described. In the correction value calculation mode, as in the first embodiment, an offset error that is a main factor of waveform distortion,
This is a mode for obtaining a correction value for removing an amplitude error and a phase difference error. As described in the conventional example and the first embodiment, as the slit plate 6 rotates, the photocurrent signal with a 90 ° phase difference in four phases is output from the light receiving element 7. This photocurrent signal is passed through the four current-voltage conversion circuits 101 to 104, and the 90-phase photocurrent signal is generated in four phases corresponding to the cycle of one slit pitch.
° Sine wave voltage signals 181,281,381,4 with phase difference
It is output as 81.

Next, the four-phase sine wave voltage signal 18 having a 90 ° phase difference obtained from the current-voltage conversion circuits 101 to 104.
180 degrees out of 1,281,381,481
A signal having a phase difference, that is, a sine wave voltage signal 18
1 and 381 are also sinusoidal voltage signals 281 and 481.
And are input to the differential operation circuits 131 and 132. The differential operation circuits 131 and 132 perform a differential operation and output differential sine wave voltage signals 581 and 681.

Subsequently, the voltage signals 581 and 681 with a two-phase and 90 ° phase difference from the differential operation circuits 131 and 132 are converted into A / D conversion means 1 in the optical encoder 999, for example.
It is taken into the waveform calculation means 902 via 12. For example, when the number of slits in the slit plate 6 is 2 ⁸ (256), 2 × 2 ⁸ (5
12) sine waves are output. The waveform calculation means 902 outputs correction data composed of amplitude correction data, offset correction data, and phase difference correction data corresponding to each sine wave.

Regarding the offset, since the offset component is removed in the differential operation circuits 131 and 132, the offset error (ΔX
_{Since only AC1 to AC256} and ΔX _{BD1 to BD256} ) are obtained, the means for removing the offset used in the first embodiment is unnecessary.

Next, the amplitude error (ΔY) obtained by removing the reference amplitude Y from the 2 × 2 ⁸ amplitudes by the waveform calculation means 902.
_AC1-AC256 , ΔY _BD1-BD256 ),
2 ^eight sine wave phase retardation to remove the reference phase difference 90 ° from difference error of ([Delta] [theta] _1-256) for calculating, respectively.
These amplitude errors (ΔY _AC1-AC256 , ΔY
_BD1-BD256 ), offset error (ΔX
_AC1-AC256 , ΔX _BD1-BD256 ) and the phase difference error (Δθ _1-256 ) are averaged, and the calculation results are respectively calculated as the amplitude average error (ΔY).
_{AC_mean} , ΔY _{BD_mean} ), offset average error (ΔX _{AC_mean} , Δ
X _{BD — mean} ), phase difference average error (Δθ _mean )
To calculate.

These amplitude average error, offset average error, and phase difference average error are calculated, for example, by the microcomputer 1.
The amplitude correction value (ΔY
_{AC_corr ect, Δ}
Y _{BD_correct} ), offset correction value (ΔX
_{AC_cor rect} , Δ
X _{BD_correct} ), phase difference correction value (Δθ
_{correc t} ). Amplitude correction data, offset correction data, which are actually digital data,
The correction data composed of the phase difference correction data is written.
In the correction value calculation mode, such correction data is calculated.

Next, the normal detection mode will be described.
First, generation of upper data will be described. As described in the conventional example and the first embodiment, the differential sine wave voltage signals 581 and 68 taken in the microcomputer 100.
1 is a microcomputer 1 as shown in FIG.
The binary signal 121, which is a square wave, is output to the comparator 110 in 00. Then, the binary signal is transferred to the counter means 111 in the microcomputer 100.
The upper data 122 is obtained by counting as the number of sine waves at.

Next, generation of lower data will be described. The differential sine wave voltage signal taken into the microcomputer 100 is A / D converted by the A / D conversion means 112 to obtain differential sine wave digital data. The A / D conversion means 112 described here is connected to the waveform calculation means 902 as in the first embodiment.
It may be the same as 2.

Normally, the differential sine wave digital data 123 output from the A / D conversion means 112 is digital data of a signal represented by the following mathematical formula.

[0065]

[Equation 7]

Such differential sine wave digital data 12
3 is input to the correction value calculation means 115 inside the microcomputer 100. The correction value calculation means 115 fetches the amplitude correction data, the offset correction data, and the phase difference correction data in the memory 702 and calculates them, and outputs the following correction lower data 126 in which the influence of the waveform distortion is reduced.

[0067]

[Equation 8]

Then, the interpolation means 113 outputs the lower data 124 after performing the interpolation multiplication processing on the corrected lower data. The upper data thus obtained is combined with the lower data to obtain angle data. As explained above,
An upper-level data obtained by counting the number of slits and lower-level data obtained by electrically dividing one sine wave are combined to obtain a high-resolution and high-precision optical encoder.

The second embodiment has been described above. Although the optical encoder of this embodiment has been described as being a rotary encoder, as an embodiment according to claim 13 of the present invention, a substantially rectangular slit plate in which the detection tracks are arranged in a substantially straight line is provided. An optical linear encoder that is fixed and moves along the slit plate in a linear direction while the light emitting element and the light receiving element are facing each other to detect the amount of displacement in the linear direction. It may have a value calculation function. In this case as well, an optical encoder having high resolution and high accuracy can be provided as in the optical rotary encoder.

[Third Embodiment] Next, an optical encoder according to a third embodiment of the invention will be described. FIG. 5 shows a block diagram of the optical encoder and its peripherals according to the third embodiment. In the present embodiment, although the configuration is almost the same as that of the second embodiment, since the calculation method of the correction data is different, the computer 100
Waveform calculation means 90 for calculating a plurality of types of correction data within
3, a memory means 703 having a plurality of areas for writing a plurality of types of correction data, and a correction value calculation means 119 for handling a plurality of types of correction data are different. In this embodiment, the correction data is obtained with n = 4. Other than this, the structure of the optical encoder, the light receiving element layout, and the operation of the light receiving element are the same as those of the conventional example, and therefore detailed description thereof will be omitted.

First, the correction value calculation mode of this embodiment will be described. Similar to the second embodiment, the correction value calculation mode is a mode for acquiring a correction value for removing an offset error, an amplitude error and a phase difference error, which are main factors of waveform distortion. Incidentally, 2 × 2 ⁸ pieces of sine wave signal from the 2 × 2 ⁸ pieces of amplitude error, the method of calculating the offset error and the phase difference error is detailed is the same as the first embodiment description is omitted.

For example, the slit plate 6 of the optical encoder
Of the sine wave obtained in one rotation of, the first 1 to 64
The average value of each of the amplitude error, the offset error, and the phase difference error of the sine wave up to the first is calculated as the first amplitude average error (Δ
Y _{AC_correct_1_64} , ΔY
_{BD_cor rect_1_64} ), first offset average error (ΔX _{AC_correct} , ΔX
_{BD_corre ct),} a first phase difference average error Δθ
_{correct — 1 — 64} ). Here, the first sine wave is, for example, a sine wave obtained until the slit plate 6 of the optical encoder rotates and moves from one slit to the next adjacent slit.

Similarly, the average values of the amplitude error, the offset error, and the phase difference error of the 65th to 128th sine waves are referred to as the second amplitude average error, the second offset average error, and the second phase difference average error, respectively. 129-192
The average values of the amplitude error, the offset error, and the phase difference error of the sine wave up to the th are referred to as the third amplitude average error, the third offset average error, and the third phase difference average error, respectively. The average values of the amplitude error, the offset error, and the phase difference error of the wave are respectively the fourth amplitude average error, the fourth offset average error, and the fourth
It is called the phase difference average error.

Then, each of the first to fourth average errors is written as a correction value in the memory 703 shown in FIG. However, the first amplitude, offset and phase difference correction values are stored in the memory area 115, the second amplitude, offset and phase difference correction values are stored in the memory area 116, and the third amplitude, offset and phase difference correction values are stored in the memory area 115. The fourth amplitude, the offset, and the phase difference correction value are written in the memory area 117, respectively. Note that the memory means 703 is actually written as digital data.

Then, in the normal detection mode, the second
The correction is performed in the same manner as the correction performed in the embodiment, but when the mechanical angle of the optical encoder is 0 to 90 °, that is, when the sine wave is the 1st to 64th, the first amplitude, offset, and phase difference complementary value Is used to correct the differential sine wave digital data 123 output from the A / D conversion means 112 in the microcomputer 100, for example. Similarly, when the mechanical angle is 90 to 180 °, 180 to 270 °,
In the case of 270 to 360 °, the second, third, and
The correction calculation is performed using the fourth amplitude, offset, and phase difference correction data.

As described above, the angle calculation is performed by selecting from the four correction data according to the mechanical angle of the optical encoder, that is, the detected angle. Note that the angle calculation in the normal detection mode is the same as that in the second embodiment, and will be omitted. The corrected lower data 126 is input to the interpolation means 113, and the lower data 124 is output. Then, the angle data 206 is output in combination with the upper data 122 and the lower data 124. With such a configuration, it is possible to obtain an optical encoder with higher resolution and higher accuracy.

The third embodiment has been described above. Although the optical encoder of this embodiment has been described as being a rotary encoder, as an embodiment according to claim 13 of the present invention, a substantially rectangular slit plate in which the detection tracks are arranged in a substantially straight line is provided. An optical linear encoder that is fixed and moves along the slit plate along the linear direction while the light emitting element and the light receiving element are opposed to each other to detect the amount of displacement in the linear direction. It may have a value calculation function. In this case as well, an optical encoder having high resolution and high accuracy can be provided as in the optical rotary encoder.

[Fourth Embodiment] An optical encoder according to the fourth embodiment of the present invention will be described below. FIG. 6 shows a block diagram of an optical encoder and its peripherals according to the fourth embodiment. In the present embodiment, although the configuration is almost the same as that of the third embodiment, the computer 100 is different because the correction data calculation method is different.
They are different in that they have a waveform calculation means 904 for calculating a plurality of correction data and a memory means 704 provided with a plurality of areas for writing a plurality of types of correction data. In the present embodiment, the correction data is obtained with n = 256. Other than this, the structure of the optical encoder, the light receiving element layout, and the operation of the light receiving element are the same as those of the conventional example, and therefore detailed description thereof will be omitted.

First, the correction value calculation mode of this embodiment will be described. Similar to the third embodiment, the correction value calculation mode is a mode for acquiring a correction value for removing an offset error, an amplitude error and a phase difference error, which are main factors of waveform distortion. Incidentally, 2 × 2 ⁸ pieces of sine wave signal from the 2 × 2 ⁸ pieces of amplitude error, the method of calculating the offset error and the phase difference error, the second embodiment is the same as the third embodiment will be omitted.

Each error obtained by the method described in the third embodiment is written in the memory means 704 as a correction value. However, the first amplitude, offset, and phase difference correction values are stored in the memory area 115, the second amplitude, offset, and phase difference correction values are stored in the memory area 116, and so on. The correction value is written in the memory area 140, and the 256th amplitude, offset, and phase difference correction values are written in the memory area 141, respectively. Note that the memory means 704 is actually written as digital data.

In this way, the correction data for the 256 sine waves are individually written, and it is searched whether the Xth sine wave is obtained from the mechanical angle obtained by the upper data.
The correction value corresponding to this sine wave number is stored in the memory means 704.
Read from the specified area of.

In the normal detection mode, in the same manner as the correction performed in the third embodiment, when the sine wave is the first, the first amplitude, offset, and phase difference complementary values written in the memory area 115 are obtained. Is used to correct the differential sine wave digital data 123 output from the A / D conversion means 112 in the microcomputer 100, for example, the X-th amplitude error and the X-th amplitude error in this designated memory area.
The offset value and the X-th phase difference error are used as correction values, the obtained sine wave signal is corrected by the correction value calculation means 119, and the corrected lower data 126 is output.

The corrected lower data 126 is used as the interpolation means 11
3 and the lower data 124 is output. Then, the angle data 206 is output in combination with the upper data 122 and the lower data 124. With such a configuration, it is possible to obtain an optical encoder with higher resolution and higher accuracy.

The fourth embodiment has been described above. Although the optical encoder of this embodiment has been described as being a rotary encoder, as an embodiment according to claim 13 of the present invention, a substantially rectangular slit plate in which the detection tracks are arranged in a substantially straight line is provided. An optical linear encoder that is fixed and moves along the slit plate along the linear direction while the light emitting element and the light receiving element are facing each other to detect the amount of displacement in the linear direction. It may have a value calculation function. In this case as well, an optical encoder having high resolution and high accuracy can be provided as in the optical rotary encoder.

[Fifth Embodiment] The fifth embodiment according to claim 10 of the present invention will be described with reference to FIG. FIG. 7 is a block diagram of an optical encoder and its peripheral devices according to the fifth embodiment. In the fifth embodiment, the configuration of the first embodiment is modified. Instead of the waveform calculation means 901 that is integrally provided inside the optical encoder 999 in the first embodiment, the external structure is used in the present embodiment. The computer 209 installed in the computer is used. This is because the registration of the correction data in the correction value calculation mode is performed in advance before shipment from the factory, such as during manufacturing, so that the person who uses the optical rotary encoder does not have to perform the adjustment work.

For example, the A / D conversion means 210 and the computer 2 are connected to external terminals provided on the optical encoder 999.
09 is connected as shown in FIG. 7 to perform the correction data acquisition operation as described in the first embodiment, and the memory means 7
The correction data is written in 11. In this case, since the angle detection as described in the first embodiment is performed immediately when the optical encoder 999 is used, it is possible to use the optical encoder 999 with high resolution and high accuracy without performing correction work. Become. Note that the other points are the same as those in the first embodiment, and the duplicated description will be omitted.

The fifth embodiment has been described above. Although the optical encoder of this embodiment has been described as being a rotary encoder, as an embodiment according to claim 13 of the present invention, a substantially rectangular slit plate in which the detection tracks are arranged in a substantially straight line is provided. An optical linear encoder that is fixed and moves in a straight line direction while the light emitting element and the light receiving element are facing each other along this slit plate to detect the displacement amount in the straight line direction, and the block configuration and correction described in FIG. It may have a value calculation function. In this case as well, an optical encoder having high resolution and high accuracy can be provided as in the optical rotary encoder.

[Sixth Embodiment] The sixth embodiment according to claim 10 of the present invention will be described with reference to FIG. FIG. 8 is a block diagram of an optical encoder and its peripheral devices according to the sixth embodiment. In the sixth embodiment, the configuration of the second embodiment is modified. Instead of the waveform calculation means 902 that is integrally provided inside the optical encoder 999 in the second embodiment, an external device is used in the present embodiment. The computer 209 installed in the computer is used.

For example, the A / D converter 210 and the computer 2 are connected to the external terminals provided on the optical encoder 999.
09 is connected as shown in FIG. 8 to perform the correction data acquisition operation as described in the second embodiment.
The correction data is written in 12. In this case, since the angle detection as described in the second embodiment is performed immediately when the optical encoder 999 is used, it is possible to use the optical encoder 999 with high resolution and high accuracy without performing correction work. Become. In addition, except for this, the second embodiment is similar to the second embodiment, and a duplicate description will be omitted.

The sixth embodiment has been described above. Although the optical encoder of this embodiment has been described as being a rotary encoder, as an embodiment according to claim 13 of the present invention, a substantially rectangular slit plate in which the detection tracks are arranged in a substantially straight line is provided. An optical linear encoder that is fixed and moves along the slit plate along the linear direction while the light emitting element and the light receiving element are facing each other to detect the displacement amount in the linear direction. It may have a value calculation function. In this case as well, an optical encoder having high resolution and high accuracy can be provided as in the optical rotary encoder.

[Seventh Embodiment] The seventh embodiment according to claim 10 of the present invention will be described with reference to FIG. FIG. 9 is a block diagram of an optical encoder and its peripherals according to the seventh embodiment. The seventh embodiment is a modification of the configuration of the third embodiment. Instead of the waveform calculation means 903 that is integrally provided inside the optical encoder 999 in the third embodiment, an external device is used in the present embodiment. The computer 209 installed in the computer is used.

For example, the A / D conversion means 210 and the computer 2 are connected to external terminals provided on the optical encoder 999.
09 is connected as shown in FIG. 9 to perform the correction data acquisition operation as described in the third embodiment, and the memory means 7 is connected.
Four kinds of correction data are written in the area 13. In this case, since the angle detection as described in the third embodiment is performed immediately when the optical encoder 999 is used, it is possible to use the optical encoder 999 with high resolution and high accuracy without performing correction work. Become. In addition,
Except for this, the third embodiment is the same as the third embodiment, and a duplicate description will be omitted.

The seventh embodiment has been described above. Although the optical encoder of this embodiment has been described as being a rotary encoder, as an embodiment according to claim 13 of the present invention, a substantially rectangular slit plate in which the detection tracks are arranged in a substantially straight line is provided. An optical linear encoder that is fixed and moves along the slit plate along the linear direction while the light emitting element and the light receiving element are facing each other to detect the amount of displacement in the linear direction, and the block configuration and correction described in FIG. It may have a value calculation function. In this case as well, an optical encoder having high resolution and high accuracy can be provided as in the optical rotary encoder.

[Eighth Embodiment] An eighth embodiment according to claim 10 of the present invention will be described with reference to FIG. Figure 1
Reference numeral 0 is a block diagram of the optical encoder and its peripheral devices according to the eighth embodiment. In the eighth embodiment, the configuration of the fourth embodiment is modified. In the fourth embodiment, instead of the waveform calculation means 904 that is integrally provided inside the optical encoder 999, in the present embodiment, it is externally provided. The computer 209 installed is used.

For example, the A / D conversion means 210 and the computer 2 are connected to external terminals provided on the optical encoder 999.
09 is connected as shown in FIG. 10, the correction data acquisition work as described in the fourth embodiment is performed, and 256 kinds of correction data are written in the memory means 714. In this case, since the angle detection as described in the fourth embodiment is performed immediately when the optical encoder 999 is used, it can be used with high resolution and high accuracy without performing the correction work. Become. Note that the other points are the same as those in the fourth embodiment, and the duplicated description will be omitted.

The eighth embodiment has been described above. Although the optical encoder of this embodiment has been described as being a rotary encoder, as an embodiment according to claim 13 of the present invention, a substantially rectangular slit plate in which the detection tracks are arranged in a substantially straight line is provided. The optical linear encoder that is fixed and moves along the slit plate along the linear direction while the light emitting element and the light receiving element are opposed to each other to detect the amount of shift in the linear direction, and the block configuration and correction described in FIG. It may have a value calculation function. Also in this case,
As with the optical rotary encoder, the optical encoder can have high resolution and high accuracy.

[0097]

According to the present invention, it is possible to provide a highly accurate optical encoder that reduces the influence of waveform distortion.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an optical encoder according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of an optical encoder light receiving element according to the first embodiment of the present invention.

FIG. 3 is a block diagram of an optical encoder and its peripheral devices according to the first embodiment of the present invention.

FIG. 4 is a block diagram of an optical encoder and its peripheral devices according to a second embodiment of the present invention.

FIG. 5 is a block diagram of an optical encoder and its peripheral devices according to a third embodiment of the present invention.

FIG. 6 is a block diagram of an optical encoder and its peripheral devices according to a fourth embodiment of the present invention.

FIG. 7 is a block diagram of an optical encoder and its peripheral devices according to a fifth embodiment of the present invention.

FIG. 8 is a block diagram of an optical encoder and its peripheral devices according to a sixth embodiment of the present invention.

FIG. 9 is a block diagram of an optical encoder and its peripheral devices according to a seventh embodiment of the present invention.

FIG. 10 is a block diagram of an optical encoder and its peripheral devices according to an eighth embodiment of the present invention.

FIG. 11 is a configuration diagram of a conventional optical encoder.

FIG. 12 is a configuration diagram of a light receiving element of a conventional optical encoder.

FIG. 13 is a light receiving element of a conventional optical encoder and its peripheral circuit diagram.

FIG. 14 is an ideal voltage signal waveform diagram taken in by a microcomputer.

FIG. 15 is an actual voltage signal waveform diagram taken in by the microcomputer.

[Explanation of symbols]

1 Case 2 LED 3,4 Bearing 5 Hollow shaft 6 Slit plate 7 Light receiving element 8 Circuit board 9 Electronic components 11-16 Light receiving cells 21-26 Light receiving cells 31-36 Light receiving cells 41-46 Light receiving cells 18 Group A 28 Group B 38 C group 48 D group 100 Microcomputers 101, 102, 103, 104 Current-voltage conversion circuit 109 Offset removal calculation means 110 Comparator means 111 Counter means 112 A / D conversion means 113 Interpolation means 115 Correction value calculation means 131, 132 Differential Arithmetic circuit 209 A / D conversion means 210 Computer 701,702,703,704 Memory means 711,712,713,714 Memory means 901,902,903,904 Waveform operation means 999 Optical encoder

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tomoharu Nakayama             1-1 Tanabe Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa             Within Fuji Electric Co., Ltd. (72) Inventor Yasumitsu Nagasaka             1-1 Tanabe Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa             Within Fuji Electric Co., Ltd. F-term (reference) 2F103 BA07 BA08 CA01 DA01 DA12                       DA13 EA12 EA15 EB02 EB06                       EB15 EB16 EB33 ED11 ED21                       ED27 FA06 FA07

Claims (13)

[Claims] 1. A group, B group, and C formed by dividing a light receiving cell arranged on a two-dimensional plane into four groups by a substantially orthogonal dead zone.
A light receiving element having four light receiving cell arrays, a group D and a group D, and the four groups of light receiving cell arrays being arranged such that the photocurrent signals output from the four groups of light receiving cell arrays are periodic signals having different phases, and A slit plate having a light-emitting element arranged at a position facing the light-receiving element, which emits irradiation light toward the light-receiving element, and a detection track including a slit row for transmitting and blocking irradiation light from the light-emitting element. A current-voltage conversion circuit that converts a sine-wave current signal output from each light-receiving cell array of the light-receiving element into a sine-wave voltage signal; and a waveform distortion using the sine-wave voltage signal output from the current-voltage conversion circuit. Correction data generation means for generating and storing correction data for correction, and a high-order bit using a sine wave voltage signal output from the current-voltage conversion circuit Higher-order data generation means for generating higher-order data that is digital data, and correction data stored by the correction-data generation means in addition to the sine wave voltage signal output from the current-voltage conversion circuit are used to generate lower-order digital data. An optical encoder characterized by outputting a lower data generating means for generating a certain lower data and angle data obtained by combining the upper data and the lower data. 2. The optical encoder according to claim 1, wherein the correction data generation unit A / D converts the sine wave voltage signal output from the current-voltage conversion circuit to output sine wave digital data. A / D
Conversion means, waveform calculation means for calculating correction data composed of amplitude correction data, offset correction data and phase difference correction data using the sine wave digital data from the A / D conversion means, and the waveform calculation means. An optical encoder comprising: a memory unit that registers the corrected data. 3. The optical encoder according to claim 1, wherein the higher-order data generation unit binarizes the sine wave voltage signal output from the current-voltage conversion circuit and outputs a binary signal. An optical encoder, comprising: a comparator unit that performs the above operation; and a counter unit that counts based on the binary signal calculated by the comparator unit to generate upper data. 4. The optical encoder according to claim 1, wherein the lower data generation means A / D converts the sine wave voltage signal output from the current-voltage conversion circuit. A / D that outputs sine wave digital data
Conversion means, offset removal calculation means for removing offset components of the sine wave digital data from the A / D conversion means and outputting offset removal sine wave digital data, and offset removal sine wave digital from the offset removal calculation means Correction value calculation means for generating correction lower-order data from which amplitude error, offset error, and phase difference error are removed by using the data and the correction data from the correction-data generation means; and the correction lower-order data is digital data of lower-order bits. An optical encoder, comprising: 5. A group, a group B, and a group C, each of which is formed by dividing a light receiving cell arranged on a two-dimensional plane into four groups by a substantially orthogonal dead zone.
A light receiving element having four light receiving cell arrays, a group D and a group D, and the four groups of light receiving cell arrays being arranged such that the photocurrent signals output from the four groups of light receiving cell arrays are periodic signals having different phases, and A slit plate having a light-emitting element arranged at a position facing the light-receiving element, which emits irradiation light toward the light-receiving element, and a detection track including a slit row for transmitting and blocking irradiation light from the light-emitting element. A current-voltage conversion circuit for converting a sine-wave current signal output from each light-receiving cell array of the light-receiving element into a sine-wave voltage signal; and a position of 180 ° of the sine-wave voltage signal output from the current-voltage conversion circuit. A differential operation circuit that outputs a differential sine wave voltage signal by differentiating two-phase sine wave voltage signals having a phase difference, and a differential positive output from the differential operation circuit. Correction data generating means for generating and storing correction data for correcting waveform distortion using a wave voltage signal, and upper data that is digital data of upper bits using the differential sine wave voltage signal output from the differential operation circuit And a lower data, which is digital data of lower bits, using the correction data stored by the correction data generation unit in addition to the differential sine wave voltage signal output from the differential operation circuit. An optical encoder characterized in that it outputs a lower data generation means for generating and angle data that combines these upper data and lower data. 6. The optical encoder according to claim 5, wherein the correction data generating unit performs A / D conversion on the differential sine wave voltage signal output from the differential operation circuit to perform a differential sine wave digital signal. Output data A
A / D conversion means, a waveform calculation means for calculating correction data composed of amplitude correction data, offset correction data and phase difference correction data using the differential sine wave digital data from the A / D conversion means, and the waveform calculation An optical encoder comprising: a memory unit that registers the correction data calculated by the unit. 7. The optical encoder according to claim 5, wherein the higher-order data generation means binarizes the differential sine wave voltage signal output from the differential operation circuit. An optical encoder, comprising: a comparator unit that outputs a signal and a counter unit that counts based on the binary signal calculated by the comparator unit to generate upper data. 8. The optical encoder according to any one of claims 5 to 7, wherein the lower-order data generation means outputs the differential sine wave voltage signal output from the differential operation circuit to A / A to D-convert and output differential sine wave digital data
Using the / D conversion means, the differential sine wave digital data from the A / D conversion means and the correction data from the correction data generation means, correction lower data from which amplitude error, offset error and phase difference error are removed is obtained. An optical encoder comprising: a correction value calculation unit that generates the correction value; and an interpolation unit that calculates lower data that uses the corrected lower data as digital data of lower bits. 9. The optical encoder according to claim 5, wherein when the correction data including the amplitude correction data, the offset correction data, and the phase difference correction data is calculated, there is a predetermined section. An optical encoder characterized by calculating n correction data by dividing differential sine wave digital data into n ranges and writing the correction data in n areas of the memory means. 10. The optical encoder according to claim 1, wherein the waveform calculation means is an external computer. 11. The optical encoder according to claim 1, further comprising switching means for switching between a normal detection mode for performing normal detection and a correction value calculation mode for performing correction value calculation. Characteristic optical encoder. 12. The optical encoder according to claim 1, wherein the slit plate is a disc-shaped slit plate in which detection tracks are arranged in a substantially circular shape. An optical encoder characterized by being a rotary encoder that detects a displacement amount of a rotating slit plate in a rotation direction by the light emitting element and the light receiving element that are arranged to face each other with a slit plate interposed therebetween. 13. The optical encoder according to any one of claims 1 to 11, wherein the slit plate is a substantially rectangular slit plate in which detection tracks are arranged in a substantially straight line. An optical encoder characterized in that the light-emitting element and the light-receiving element face each other along a fixed slit plate while moving in a linear direction to detect a displacement amount in the linear direction.