JPS63235822A - Optical encoder - Google Patents

Abstract

PURPOSE:To detect phase data without performing switching operation, by providing a light source, a light source driver and a light receiving array. CONSTITUTION:A light source 33 is arranged in opposed relation to a light receiving array 10 and a light source 34 is arranged in opposed relation to a light receiving array 11. A light source driver 36 applies a signal (sinomegat+1) to the light source 33 and applies a signal (cosomegat+1) to the light source 34 and the luminous intensities of the light sources 33, 34 are modulated in amplitude on the basis of sinomegat and cosomegat. An adder 13 adds the outputs of photoelectric converter elements A1, B4 and an adder 14 adds the outputs of photoelectric converter elements A3, B2. Further, a subtractor 18 introduces the outputs of the adders 13, 14 to subtract the same and a subtractor 19 introduces the outputs of adders 15, 16 to subtract the same. High band-pass filters 20, 21 take out only the high frequency components of the signals introduced from the subtractors 18, 19 and comparators 23, 24 compare the signals from the filters 20, 21, for example, with 0V potential to output signals. By this method, the position data contained in the signals of the filters 20, 21 can be detected.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention has a plurality of slits provided at regular intervals, irradiates light from a light source onto a code plate, and converts the light passing through the slits into a photoelectric conversion element. The present invention relates to an optical encoder that receives light and outputs a signal according to the position of a code plate.

(Prior Art) A conventional optical encoder will be explained using FIGS. 9 and 10. FIG. 9 is a diagram showing the main part of the optical encoder for detecting position information 0, and FIG. 10 is a diagram showing the output signal when there are 41 photodiodes. In FIG. 9, light is emitted from the light source 2 to the code plate 1. iru. This code plate 1 is a plate in which slits 1b for passing light and light shielding parts 1a for blocking light are arranged alternately. light source 2
If the light emitted from the is scattered light, for example, the light
Conversion line "t array 3 (hereinafter referred to as light receiving array 3...
(For example, a photodiode can be used as the photoelectric conversion element.) Light whose illumination intensity is distributed in a sinusoidal waveform as shown in FIG. 9 is applied to the photoelectric conversion element. This light receiving array 3
The phase θ of the sinusoidal light irradiated on the code plate is determined depending on the position (or angle) of the code plate, and as the code plate moves, θ
The value of also changes. The optical encoder according to FIG. 9 and the present invention detects the phase θ of the sinusoidal light irradiated onto the light receiving array 3, and uses this phase θ to measure the position (or angle) of the code plate. . Each photodiode Ll + to 1-: output from 4 to 1. ~■4, then ■1
~■4 is expressed by the following formula.

(, −(cosθ+1) a (
1) 12- (cos (θ+π/2)+1)a
(2) 13 = (cos (θ+π) +
1) a (3) 14- (C
O3(θ+3 π/2 > + 1) a
(4) θ: A variable that changes depending on the position of the code plate 1, that is, a signal representing the position of the code plate a: Light intensity of the light source 2
When scanning at an angular velocity ω using one means SWI to sw4, a time series of number values given by equations (+) to (4) is obtained, which is a sinusoidal output V shown by the broken line in FIG.

is seen as the output of amplifier Uo with feedback resistor R. However, in order to obtain a smooth sine wave as shown by the broken line in FIG. 10, it is necessary to increase the number of foot diodes. Since the initial damping loss of the sine wave in FIG. 10 matches the above θ, the positional information θ of the board 1 can be found by comparing the phase of the output signal Vo and the scanning phase. .

(Problems to be Solved by the Invention) The advantage of the optical encoder explained in FIG. 9 is that the positional information θ of the code plate 1 can be obtained in the form of sin (ωt+θ) (waveform in FIG. 10), so It is possible to perform accurate detection.

However, it also has the following drawbacks.

■ Since the position information θ is discretized by the light receiving array,
In order to accurately reproduce the phase, the number of photodiodes must be increased.

(2) Since the phase information θ is obtained as a number value as shown in FIG. 10, a high-order filter is required to perform interpolation between each sample.

(2) The influence of switching noise generated during scanning by switches sw1 to sw4 is large.

■ With an optical encoder, the switch s
It is necessary to scan l~814. Therefore,
Since the switching speed of the switches sw1 to sw4 is limited, measurement cannot be performed when the position of the code plate changes rapidly.

■ The circuit scale of switching circuits, signal processing circuits, etc. is large.

An object of the present invention is to provide an optical encoder that can detect phase information θ without performing a switch operation.

[Means for solving problems]

In order to solve the above problems, the present invention includes: a code plate in which slits and light shielding parts are alternately provided; two light sources; and the light intensity of one of the light sources is amplitude modulated by sinωt.
A light source driver that amplitude modulates the light intensity of the other light source by COSωt, and four photoelectric conversion elements arranged so as to equally divide one period of the optical strong antinode distribution generated on the back side of the first board plate. 1.1
Two light receiving arrays are arranged facing two light sources with a code plate in between, and the phase difference in the intensity distribution of the light irradiated to the two light receiving arrays is an integral multiple of 90°. The outputs of the photoelectric conversion elements of the first and second light receiving arrays arranged as shown in FIG. circuit means (13, 14, 18, 20) for calculating and outputting No. 13 according to the position of the code plate.

〔Example〕

Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 is a diagram showing an embodiment of an electrical circuit of an optical encoder according to the present invention. Figures 2 and 3 show the positional relationship for arranging two light receiving arrays so that the phase difference of the intensity distribution of the light irradiated to the two light receiving arrays is 90', which is one of the features of the present invention, and the number of meters is 18. FIG. FIG. 4 is a time chart of the signals of each part of the first embodiment, and FIG. 5 is a diagram showing the positional relationship among the code plate, light source, and light receiving array when the device of the present invention is applied to a rotary encoder. FIG. 6 is a diagram showing the positional relationship between the code plate, the light source, and the light receiving array when the device of Kokugi Ichiaki is applied to a linear encoder. FIG. 7 is a diagram showing a case where the distance between light receiving arrays 10 and 11 is shortened by (d/4) compared to the case of FIG. 3. FIG. 8 is a diagram for explaining the arrangement of photoelectric conversion elements of the present invention.

In FIG. 2, reference numeral 1 denotes a code plate, and as shown in the figure, slits 1h and light shielding parts 1a are repeatedly arranged alternately at constant fffl intervals d. The shape of the code plate 1 may be a straight plate (see FIG. 6) or a disk (see FIG. 5). Note that when the code plate is disc-shaped, generally detected position information θ represents the rotation angle of the code plate. and,
Scattered light α and β whose light intensity is modulated are irradiated onto the code plate 1 from two light sources (not shown), and FIG. 9'crJ! As described above, a sinusoidal light intensity distribution as shown by K in FIG. 2 is generated on the back side of the code plate 1 (on the opposite side from the light source).

The phase 0 of the sinusoidal light intensity distribution shown in FIG. 2 changes as the position (or angle) of the code plate moves.

The value of this phase θ corresponds to the position or angle of the code plate as described above, so in the present invention, the value of the code plate is measured by measuring the phase θ of the sinusoidal light intensity distribution shown in FIG. Instead of measuring position (or angle).

In the present invention, the light receiving array 10. jl are respectively four photoelectric conversion elements Δ1 to A4 and B! 〜B4. These four photoelectric conversion elements are arranged so as to equally divide one round +i1J of the light intensity distribution generated on the back side of the code plate. In addition, as shown in the gnS diagram and FIG.
0 receives the light from the light source 33, and the light receiving array 11 receives the light from the light source 34.
They are arranged in a bare pattern to receive the light of. Then, the light receiving array 10.
11 are arranged at a suitable distance from each other, or are provided with suitable stray light blocking means (not shown).

Here, using FIG. 2, FIG. 3, and FIG. What does it mean to arrange the conversion element J?Explain the conditions for arranging it so that the phase difference of the intensity distribution of the light irradiated to the 12 light receiving arrays is 9σ V! Equation 8. do.

First, it is necessary to arrange four photoelectric conversion elements so that one period of the light intensity distribution generated on the back side of the code plate is divided into four equal parts.
The meaning of is explained with reference to FIG. The light-receiving array of the present invention has four photoelectric converters T, and as described briefly, it is necessary to set the phase difference between the electric signals outputted from adjacent photoelectric conversion elements to 90°. As shown in FIG. 8, the periods T+ and T2 of the sinusoidal light intensity distribution passing through the slit 1b vary depending on the distance between the code plate 1 and the light receiving array. That is, when the photoelectric conversion cables 1]+1 to PI4 are placed at a distance of 11 from the code plate 1, the circumference of the light intensity distribution 1/1 is 1, and when placed at a distance of 11ff/2, The period of 2 in the light intensity distribution is T2. Therefore, when placing the light receiving array 31 at a distance of 111111+ from the code plate 1, the period T+ is divided into four equal parts.
In addition, when placing them at a distance of 12, each photoelectric conversion cord is placed at a distance of 12 times, which divides the period - 2 into 4 equal parts.
Since the four photoelectric conversion elements are arranged at equal intervals in the light intensity distribution 91, the output signals 1 of adjacent photoelectric conversion elements have a phase difference of 90° from each other.

Next, the conditions for arranging the 12 light-receiving arrays so that the phase difference of the intensity O1 of light irradiated on them is an integral multiple of 90' will be explained using FIGS. 2 and 3.

In the present invention, the light receiving arrays 10 and 11 are arranged apart from each other as shown in FIG. rt between and the midpoint 0□ of the light receiving array 11; M is n・(d/4)
If so, then the following conditions are met. Here, n is a positive integer, and d is the slit period indicated by 11. The distance between the midpoints of the two light receiving arrays 10 and 11 is n・(
d/4), the reason why the phase difference between the intensity distributions of the light irradiated to the two light receiving arrays is an integral multiple of 90° will be explained.

In order to make it easier to understand, the distance between the code plate 1 and the light receiving array 10.11 is made close to each other, and the arrangement layer 111d of the slits 1b of the code plate 1 and the sinusoidal light intensity distribution are A case will be explained in which the phases are the same.

In such a case, since the four photoelectric conversion elements (A+ to A4 and B1 to B4) are arranged at equal intervals during the slit period d (see Figure 2), the adjacent photoelectric conversion elements The phase difference between the electrical signals is 9σ. (1 et al., slit 1b
The distance of <1/4 of the array layer lid is equivalent to 9σ when viewed in terms of the sinusoidal phase of the light intensity. Since the electrical signal of the photoelectric conversion element is synchronized with this light intensity, (d
/4) The phase difference between the electrical signals of the photoelectric conversion element that is 1lff is 9σ. Therefore, two light receiving arrays 10°11
From 411, electrical signals with a phase relationship as shown in Fig. 3 are generated.
It will be done. FIG. 3 is a diagram showing the relationship between the phase of the slit arrangement of the corresponding code plate 1 and the electrical signal output of each photoelectric conversion element, with one part of the light receiving array 10.degree. 11 taken out from FIG. 2. As shown in FIG. 3, the phase of the electrical signal obtained from the light receiving array 10/)% (the waveform in FIG. 3 (i) and the electrical signal obtained from the light receiving array 11) (see FIG. (11) waveform) is different by a factor of 90 degrees. FIG. 3 shows an example where the phase difference is 180°.

On the other hand, as will be explained in detail later, in the present invention, the above-described electrical signals whose phases differ by 90 degrees from each other are extracted from the respective photoelectric conversion elements constituting the two light receiving arrays 10 and 11, and converted into these signals. 't4 calculation must be added.

To explain using FIG. 3, the photoelectric conversion element A1 of the light receiving array 10 and the photoelectric conversion element B4 of the light receiving array 11 are 90
Since there is a phase difference of .degree., these 81 and 84 are taken out as bare. Similarly, bears A2 and 83, bears A3 and 82, and bears A4 and 81 are taken out.

Here, since the distance W1 (d/4) corresponds to 9α as described above, the midpoint between the two light receiving arrays 10 and 11 is 01.0
If the distance between the two is n・(d/4”), it is always 90°
Signals with different phases are multiplied by 1!7.

Hereinafter, it will be explained that according to the present invention, a signal can be obtained according to the position of the code plate.

The light α from the light source 33 that is irradiated onto the light receiving array 10 is s
Since it is modulated by inωt, a can be expressed by equation (5) if the light intensity of the light α is defined as a.

a-sin ωt + 1
(5> Similarly, the light β from the light source 34 that illuminates the light receiving array 11 is modulated by COSωL, so if the light intensity of the light β is b, then b is expressed by equation (6).

b=cosωt + 1 (
6) t: Time ω: Modulation angular velocity ko and 'C' light α at (sinωt+1) 11 +
The reason why I+ is selected is to prevent the signal (sin ωt+1) applied to the light source 33 from becoming negative so that the period during which the light source 33 (e.g., a light emitting diode) does not emit light is only for a moment. +1).The same applies to the light β.

Now, the relationship between the light receiving arrays 10 and 11 is shown in FIGS.
As shown in the figure (that is, photoelectric conversion elements Δ1 and 84
．． A2 and 83. The phase difference between A3 and 8g, Aa and 81 is 90
°).

If the electric signal output from each photoelectric conversion element A+ to A4 and B+ to B4 is the same as this element number, 16, then the electric signal output of each photoelectric conversion element is expressed by the following equation.

Δ, = (sin O+ 1) a
(7) A2 =
(Sin (θ+π/2) +1) a−(CO
SO+1) a (8)Δ3-
(sin(θ+π) +1) a-(-sino+1
) a (9) A4 − (s
in <θ+3π/2) +1 1 a=(-C
OS θ+1) a
OωB+-(-sin θ+1) b
(I+)82 = (-cosθ+
1)b (12)33- (sin
θ+1)b (13)(
34=(CO8θ+1)b
(14) Photoelectric conversion elements A1 and 8a, A2 and B3, A3 and 32, A4 and B with a phase difference of 90' as described above
.

When 01 to 04 are extracted and added, each addition result 01 to 04 is expressed by the following formula. In addition, in this case, a and b are expressed by equation (5) and (
6) Substitute the expression.

Cl -8+ +8. -cos (ω is one θ) + (s
inθ+COSθ+sin ωt+cos ωt)−
2)...(15) C2-A2 +3. -5in (ω is 10) + (si
nθ+COSθ+sin ωt+cos ωt+2)・
...(1G) O3-A3 +82--cos (ω is one θ) 4(-
sin θ−COS θ+sin ωt+cos ωt+2
)...〈17) Ca −A4 +B+ −−3in (ωt+θ
)4(-3inθ-CO8θten sin ωt+cos
ωt+2)... (18) Here, by subtracting the following formula for Cl-04, G
, G2 is 151.

G+=C+C cos(ωt-θ) +27:5i11 (θ+π/4) ・(1(1
)G2-02 Cm -2sin (ω is 10) sin (θ +-π /2>
-(20) Here, in the present invention, since the position of the code plate 1 is small, the angular velocity ω of the modulation signal applied to the light source is extremely fast compared to the speed. That is, if we set the ax θ(ω) and extract only the high frequency component, then G+(y(21) in equation (19)
), and G2 in equation (20) becomes M in equation (22).
It becomes 2.

M+ = 2cos (ω is one θ)
(21) M2-2sin (ω is 10)
(22) As described above, the signal M1. which includes the phase angle θ of the code plate 1. Those skilled in the art can easily obtain M2 and then calculate θ by IE. In this way, the electric signals obtained from the light receiving array 10.11 as explained in FIG. 2 and FIG.
2) By adding the calculation shown in equation 2, the phase angle θ of the code plate can be obtained.

Hereinafter, the specific configuration and operation of the present invention will be explained with reference to FIG.

In FIG. 1, 10.11 is a light receiving array as explained in FIG. 2 and ff13. 13 to 1G are adders, and the adder 13 adds the outputs of the photoelectric conversion elements A+ and B4.
The adder 14 adds the outputs of the photoelectric conversion elements A3 and 82, the adder 15 adds the outputs of the photoelectric conversion elements A2 and 133, and the adder 16 adds the outputs of the photoelectric conversion elements A4 and 8+. Note that each of the Ff amplifiers 13 to 16 can be easily constructed of, for example, amplifiers 1 to U4 and resistors r1 to r4, as shown in FIG. 18 and 19 are subtractions, and the subtracter 18 introduces the outputs of the adders 13 and 14 and subtracts them. Further, the subtracter 19 introduces the outputs of the agitators 15 and 16 and subtracts them.

The subtracters 18 and 19 are, for example, amplifiers 4 as shown in FIG.
It can be easily configured with U5*U6 and resistors r5 to r12. 20 and 21 are high-pass filters (hereinafter referred to as LI P filters), and subtractors 18 and 19
23 and 24 are comparators, which extract only the high frequency components of the signal introduced from the HP filter 2.
By comparing the signal introduced from 0.21 with, for example, the Qv potential, the introduced signal is converted into a rectangular wave A and output. 26.27 is a counter,
A start pulse is introduced from a light source driver, which will be described later, and the output be of comparators 23 and 24 is input, and the falling edge time of the output signal of the shimparators 23 and 24 is measured from the time when the start pulse is generated.

Reference numeral 29.30 denotes a latch circuit, which inputs the output of the counter 26.27, latches it, and outputs it.

31 is a processor which adds a sieve to the outputs of counters 26 and 27 introduced via latch circuits 29 and 30,
It outputs a signal according to the position of the code plate 1.

Reference numerals 33 and 34 denote light sources, which are composed of, for example, light emitting diodes. This light source 33 is arranged facing the light receiving array 10 as shown in FIGS. 5 and 6, and the light source 34 is arranged facing the light receiving array 11. 36 is a light source driver that applies a signal (sinωt・t1) to the light source 33, a signal (COSωt+1) to the light source 34, and
The light intensity of 3.34 is amplitude modulated by sinω and COSωt. Furthermore, this light source driver 36 is configured to, for example,
, . . . The start pulse occurring at 2nπ is added to the counter 26.27. 37 is an n oscillator, which applies one or both of sin ω and COS ωt signals to the light source driver 36.

The operation of the circuit shown in FIG. 1 configured as above will be explained with reference to FIG. 4. Note that FIG. 4 is a time chart of the first joint portion.

Since a modulation signal is applied to the light sources 33 and 34 from the light source driver 3G, the light source 33 irradiates the code plate 1 with light α having the light intensity expressed by the above equation (5), and the light source 34 irradiates the code plate 1 with the light α having the light intensity expressed by the above equation (5). ) The code plate 1 is irradiated with light β having a light intensity expressed by the equation.

A light receiving array 10.11 is arranged to face the light sources 33.34 with the code plate 1 in between. As explained in detail in FIGS. 2 and 3, the distance between the midpoints 01 and 02 of the two light receiving arrays 01.11 is n·(d/4). For example, the arrangement of the light receiving array 10.11 is as shown in FIGS.
In the figure, from the photoelectric conversion cables A1 to A4 and 81 to B4 constituting the light receiving arrays 16 and 11, the (7
) to (14) are output.

As mentioned above, the outputs of the photoelectric conversion elements A+ and [34, A2 and Bz, A3 and 82, and A4 and 81, which have a phase difference of 90°, are added to the adders 13 to 1G, respectively, so that each pruritus The output of brightener 13 is CI, and the output of brightener 14 is 0.
3+The output of the adder 15 is 021 The output of the adder 16 is C4
Then, these C1 to C4 are as described above (15) to (18
) The signal shown by the formula is roaring.

The subtracter 18 introduces the outputs C+ and C3 of the adders 13 and 14 and performs the calculation CI 03> and outputs the signal @GI, and the subtracter 19 introduces the outputs C2 and C4 of the adders 15 and 16. 02C4) and outputs the signal G2. Therefore, the output G7 of the subtracter 18 and the output G2 of the M calculator 19 become the signals shown by the above-mentioned equations (19) and (20).

Furthermore, as described above, the angular velocity trace ω of the modulation signal applied to the light source is extremely fast compared to the speed at which the position of the code plate 1 moves, so fθ(ω).

Then, in HP filter 20.21, equation (19), (
Since only the high frequency component is extracted without being shown in equation 20), the output M+ of the IP filter 20 and the output M2 of the HP filter 21 become signals shown in the above equations (21) and (22).

The output waveform of this 11P filter 20.21 is shown in Figure 4 (1
) is shown with a solid line. That is, the output M1. of the HP filter 20.21. M2 is a signal that changes as shown by the solid line in FIG. 4 (1) as time t passes. In FIG. 4, in order to make the invention easier to understand, the coefficients on the right sides of equations (21) and (22) are depicted with "2'° being 1".

The dotted line in FIG. 4 (1) shows the modulation waveforms (sinωt and cosωt) of the light intensity emitted from the light sources 33 and 34,
It is a signal of θ−〇. The dotted line waveform in FIG. 4(1) can also be regarded as a modulation signal applied from the light source driver 36 to the light sources 33 and 34. In this way, the modulation signal applied to the light sources 33 and 34 is also No. 13, which changes as time t passes as shown in FIG. 4(1).

1) θ′° included in the output signal of the filter 20.21 is the code plate 1 digit V!l (or rotation angle)
b takes a value corresponding to "θ'."

This is a device that outputs a signal corresponding to the

As described above, the light source driver 36 has, for example, ω=0,
The start pulses generated by the odor at 2π, . Further, comparators 23 and 24 output M1. Since M2 is compared with the ground potential, its output waveform will be as shown in Figure 4 (io) and (. Counting ends at the edge. Therefore, the period T1 shown in Figure 4)
Published accordingly! A numerical value is obtained. The counter 21 starts counting at the rising edge of the start pulse and finishes counting 11 at the falling edge of the comparator 24. Therefore, the fourth
A count value corresponding to the period ``2'' shown in Figure (V) is obtained.

This period T1. T2 is +++, (V), in Figure 4.
(It is clear from VD that it is expressed by the following formula.

D1-(π/2)→-θ (23
) “2−π−θ
(24) Below the output of this counter 26.27 + * T
2 is read into the processor 131 via the latch circuits 29 and 30, and the following equation is performed.

T+ T2-20 (π/2) (2
5) In this way, the signal θ having a value corresponding to the position (or rotation angle 11) of the code plate 1 is obtained from the processor 31.

Here, there is a range r of O≦θ≦2π, and θ is found between 0 and π. Therefore, θ in J3 in the range of 0 to ・π
can be obtained, the present invention can be easily applied to the rotary motor 1 using known techniques.

Note that "θ" is T1 in equations (23) and (24). T
You can find 6 from 2. That is, two circuits having the same configuration (a first circuit consisting of 13, 14, 18, 20, 23, 26, 29, and 15.16.21.24.27.
A second circuit consisting of 30 circuits) is provided.
θ'' can be found by The reason for this is clear from the configuration of FIG. 1. That is, the first circuit (13, 14
, 18, 20, 23, 26, 29) have a light receiving array 10.
Two photoelectric conversion elements A1. A3 and light receiving array 1
This is clear from the configuration in which only two photoelectric conversion elements B4.82 of 1 are added.

However, better characteristics can be obtained by providing two circuits, the first and second circuits, as shown in FIG. This is because the outputs of the two symmetrical circuits are reduced by the prohisser 31, so that the effects of eccentricity of the code plate and fluctuations in the light intensity of the light source are canceled.

The explanation will be given after the ISO, but FIGS. 5 and 6 will be explained below. FIG. 5 is a diagram without showing a rotary encoder using the present invention, and (1) in the figure is a diagram of (11) viewed from the P direction. For example, the code plate 1 is connected to the rotating shaft 40 of a motor.
The light sources 33 and 34 and the light receiving arrays 10 and 11 explained in FIG. 2 are arranged bare as shown in the figure. At this time, these two bears (the bear of the light source 33 and the light receiving array 10, and the bear of the light source 34 and the light receiving array 11) are connected to the shaft 40.
It is desirable to arrange them at symmetrical positions with respect to the axis of symmetry.

The reason for this is that the influence of the eccentricity of the code plate 1 can be reduced, and the unbalance of the brightness of the two light sources can be reduced, so that the phase angle θ of the code plate can be measured with high precision. Because you can. Since the device according to the present invention is a device that can measure the phase angle θ of the code plate 1, the fifth
The figure also shows that the rotation speed of the motor can be measured.

Moreover, even if the rotational speed of the motor is very high, unlike the conventional device shown in the seventh factor, there is no need for a switch SW, so even a high rotational speed can be easily measured.

Fig. 6 is a diagram showing an example of a beam near end = 1-da, in which the code plate 1 moves in the direction of the arrow;
In the figure, it is possible to measure the movement of this code plate.

It has been explained above that if the distance between the midpoints of the two light receiving arrays is n·(d/4), a phase difference of 9σ is always obtained. In the examples of FIGS. 2 and 3, photoelectric conversion element A! and 84. The iO phase difference between A2 and 01, A3 and 8□, and A4 and 81 was 90°. Here, FIG. 7 shows a case where the distance between the light receiving arrays 10 and 11 is shortened by (d/4) from the case of FIG. 3, and it will be explained that the present invention is applicable even in this case.

From the diagram (1) in FIG. 7, the outputs of the photoelectric conversion waters rΔ1 to A4 constituting the light receiving array 10 are the same as the formulas (7) to CΦ described above. On the other hand, each photoelectric conversion element constituting the light receiving array 11 placed at a new position is moved from 8+' to B4-, etc.
The electrical signal output of [3+- to B4- is (1
Since the curve is as shown in 1), the equations (2G) to (29) are obtained.

[3+ ′-(cosO+1)b (
26) B, --(-sinθ+1)b
(27) Q3= −(−CO8θ+1)b
(28)8m --(sin θ+1)b
(29) Therefore, when two light receiving arrays are arranged as shown in Fig. 7, A1 and [31
-, A2 and B4-9 A3 and 83', Aa and 82- are added to the adders 13 to 16, then the (15
) to (18), the same operation as below can be used to measure .degree. ".theta.".

[Effects of the present invention]

As described above, according to the present invention, the light intensity of two light sources is width modulated with a 9σ phase relationship of sinωt and COSωt, and the light that has passed through the code plate is modulated with an appropriate phase relationship by the photoelectric conversion element. (1) The number of photoelectric conversion elements is small and the configuration is simple.

(2) The present invention does not require a high-order filter that performs interpolation between simple filters, which is required in conventional devices.

(2) Since the switch means sw1 to sw4 of the conventional device are not used, it is possible to respond to a high moving speed of the code plate to be measured.

GI) It is easy to extract phase information θ.

Effects such as this can be obtained.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of the electrical circuit of an optical encoder according to the present invention, and FIGS. 2 and 3 are one of the features of the present invention.
Figure 4 is a diagram explaining the positional relationship for arranging the two light receiving arrays so that the phase difference in the intensity distribution of the light irradiated on them is an integral multiple of 90°. Fig. 73 is a diagram showing the positional relationship between the code plate, light source, and light receiving array when the device of the present invention is applied to a rotary 1 encoder, and Fig. 6 is a diagram showing the positional relationship between the code plate, the light source, and the light receiving array when the device of the present invention is applied to a linear 1 encoder. Figure 7 shows the positional relationship between the code plate, the light source, and the light receiving array when applied to the light receiving array. Figure fJ18 is a diagram showing the arrangement of the photoelectric conversion elements of the present invention, Figure 9 is a diagram showing an example of the configuration of the conventional means, and Figure 10 is a diagram showing a sampled light receiving array. FIG. 1... Code plate, 1o, ii... Light receiving array, A
t~Δ4, B, ~B4...photoelectric conversion element, 13~16
...Adder, 18, 19...Flat reducer, 20.21.
...1-I P filter, 23.24... ] umbalator, 26.27... counter, 31... filter, 33.34... light source, 36... light source driver...
Figure 4 Figure 5 Tail 6 Figure 8 Light

Claims (2)

[Claims] (1) A code plate in which slits and light shielding parts are alternately provided, two light sources, and a light source that amplitude modulates the light intensity of one of the light sources by sinωt and amplitude modulates the light intensity of the other light source by cosωt. It has a driver and four photoelectric conversion elements arranged so as to equally divide one period of the light intensity distribution generated on the back side of the code plate, and is placed facing two light sources with the code plate in between. first and second light receiving arrays, each of which is arranged such that the phase difference between the intensity distributions of the light irradiated to the two light receiving arrays is an integral multiple of 90°; and the light intensity Circuit means for introducing the outputs of the photoelectric conversion elements of the first light receiving array (10) and the second light receiving array (11) whose distribution phases are different from each other by 90 degrees, and calculating and outputting a signal according to the position of the code plate. (13, 14, 18, 20) and an optical encoder. (2) removing the photoelectric conversion elements located at every other position among the four photoelectric conversion elements constituting each of the light receiving arrays;
2. The optical encoder according to claim 1, wherein the first and second light receiving arrays each include a photoelectric conversion element.