JP2749987B2 - Rotary encoder - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a rotary encoder, and more particularly, to a rotary encoder that photoelectrically detects a signal corresponding to a relative rotation of an object.

2. Description of the Related Art As a measuring device for measuring the rotation amount of a cylindrical rotating body, there is a rotary encoder proposed by the present applicant in Japanese Patent Application Laid-Open No. 63-81212.

This rotary encoder is an excellent measuring device that can measure the amount of rotation of a cylindrical rotating body with a simple configuration and relatively high resolution.

This effect is achieved by providing an imaging optical system inside the rotating body (hollow portion), and using this imaging optical system, the image of the grating in the first area on the side surface of the rotating body can be converted into the first area with respect to the rotation axis of the rotating body. This is achieved by projecting onto the grid of the second region on the side opposite to that of FIG.

[Object of the invention]

The present invention relates to an improvement of the rotary encoder disclosed in the above publication, and an object of the present invention is to provide a rotary encoder that can be further downsized.

[Means and actions for achieving the object]

In order to achieve the above object, the present invention provides a hollow body, a grating arranged in the hollow body along the rotation detection direction, and irradiating light to the first region where the grating is formed from the inside of the hollow body,
Light irradiating means for projecting a Fourier image of the first area grid on a second area grid different from the first area of the hollow body by light reflected by the first area grid; and Light detection means for receiving the light reflected by the two regions of the grating is provided.

In the present invention, since the Fourier image of the grating in the first area is projected onto the grating in the second area, it is not necessary to provide an imaging optical system inside the hollow body (hollow portion). Therefore,
The diameter of the hollow body can be easily reduced, and an extremely small rotary encoder can be provided.

〔Example〕

FIG. 1 is a perspective view showing a first embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a semiconductor laser, which emits a coherent light beam (monochromatic light) having a wavelength λ. A collimator lens system 2 converts a divergent light beam from the semiconductor laser 1 into a substantially parallel light beam in the xz plane. The collimator lens system uses, for example, an anamorphic lens, and emits light in a convergent state in a direction perpendicular to the xz plane. Reference numeral 3 denotes a hollow body, here a cylindrical rotating body, which rotates in a direction indicated by an arrow with a shaft 5 as a rotation axis parallel to the generatrix of the cylinder. The rotating body 3 is connected to a drive shaft such as a motor via a connector (not shown), and is used as an optical scale for detecting a rotation amount of the drive shaft. Also, the shaft 5 and the center axis of the drive shaft coincide, and the center axis of the rotating body and the shaft 5 also substantially coincide.

The rotating body 3 is made of a member that reflects light, such as metal, glass, or plastic. A plurality of slits 30a are arranged on the side surface 30 of the rotating body 3 at equal intervals along the rotation direction of the rotating body 3 with a pitch P. Accordingly, the light incident on the side surface 30 of the rotating body 3 passes through the slit 30a, and a portion 30 between the slits 30a.
Reflected by b. That is, 30a is a light-transmitting portion, 30b is a reflecting portion, and these light-transmitting portions 30a and the reflecting portion 30b are alternately and regularly arranged along the rotation direction to form a grating, and constitute an optical scale. . 4 is a photoelectric conversion element,
Consists of a photodetector. And the photoelectric conversion element 4
Outputs an electric signal corresponding to the intensity of light incident on the light receiving surface 40.

 6 and 7 are semi-transparent mirrors.

FIG. 2 is a cross-sectional view of the first embodiment of the present invention, and the present invention will be described with reference to FIG.

Emits a semiconductor laser 1 and a collimator lens system 2
As a result, the light that has become a substantially parallel light beam is partially reflected by the semi-transparent mirror 6 to the left in the drawing, and is incident on the first region 31 of the rotating body 3.

The light reflected by the first region reaches the semi-transmissive mirror 6 again, passes through it, further passes through the semi-transparent mirror 7, and is irradiated on the second region 32.

Of the lattice of the first region 31 and the lattice of the second region 32 of the rotating body 3,
The distance d along the optical axis 12 (hereinafter referred to as “the diameter d of the rotator”) is represented by P for the grating pitch and λ for the wavelength. Is set to meet. Thus, the rotating body 3
Is set, the image of the lattice of the first region 31 on the side surface 30 of the rotator 3 is directly projected onto the lattice of the second region 32 without providing an imaging optical system in the hollow portion of the rotator 3. it can.
The lattice image projected here is called a Fourier image, and is generated by a self-imaging effect of the lattice accompanying the light diffraction phenomenon. Since the rotating body 3 of the present embodiment has a cylindrical shape,
Although the Fourier image is slightly curved and the contrast is apt to decrease, if the semiconductor laser 1, the collimator lens system 2, the semi-transparent mirrors 6, 7 and the rotating body 3 are configured to satisfy the following conditions, there is a practical problem. Absent.

The above description has been made with respect to the light flux in the direction parallel to the paper surface shown in FIG. 2, but the light flux in the direction perpendicular to the paper surface will be described below.

 FIG. 3 is a top view of the embodiment of the present invention.

As described above, the light emitted from the collimator lens system 2 is substantially parallel in the direction parallel to the plane of FIG. 2 (in the xz plane), but is substantially perpendicular to the plane of FIG. In the direction parallel to the plane of the drawing (within the xy plane), the light beam becomes an approximately parallel light beam after being reflected on the inner surface of the rotating body 3.

In other words, the point of distance from the anti-slope of the rotating body 3 to the half of the radius of curvature of the anti-slope of the rotating body 3 has a condensing point.

By doing so, the reflected light from the cylindrical reflecting portion of the rotator becomes a substantially parallel light flux and travels to the second region 32.

 The principle of rotation angle detection will be described in detail with reference to FIG.

The light beam from the semiconductor laser 1 is converted by the collimator lens system 2 into a parallel light beam after being reflected by the anti-slope of the rotating body 3, and this light beam is used to convert the light into a first area of the rotating body 3.
Lighting 31. This light beam is diffracted by the grating of the first region 31, and diffracted light of 0 order, ± 1 order, ± 2 order is generated from the grating of the first region 31, and two or three of the 0 order light and the ± 1 order diffracted light are generated. Due to the interference between the light beams, the Fourier image of the grid in the area 31 is projected on the grid in the area 32 of the rotating body 3. The light and dark pitches of this Fourier image are the pitch P
Becomes equal to Further, as described above, the Fourier image is curved, but the curvature occurs along the curved surface of the region 32 and does not significantly affect the measurement accuracy.

As shown in FIG. 3, if the rotating body 3 is rotating in the direction of arrow 100 (CCW direction: counterclockwise), the Fourier image moves in the direction of arrow 110 (CW direction: clockwise). At this time, the grid of the area 32 on which the Fourier image is projected is indicated by an arrow.
It is moving in 100 directions. Therefore, the relative angle change between the Fourier image and the grid of the region 32 when the rotating body 3 is rotated by the angle θ is 2θ, and the rotation angle can be measured at twice the resolution of the grid pitch.

The grating in the region 32 is illuminated with the Fourier image of the grating in the region 31, and the light reflected by the grating in the region 32 is incident on the light receiving surface 40 (not shown in FIG. 3) of the photoelectric conversion element 4. The photoelectric conversion element 4 converts the received light into an electric signal, and the rotation angle of the rotating body 3 is measured based on the signal. In the rotary encoder of this embodiment, when the rotating body 3 rotates by the angle θ as described above, the Fourier image of the grid of the area 31 and the grid of the area 32 rotate by the angle 2θ relatively. Is n, 2n sine-wave pulses are output from the photoelectric conversion element 4 per rotation of the rotating body 3. The rotation angle is measured by sequentially counting the sine wave pulses. Further, the rotation speed of the rotating body 4 can be detected based on the sine wave pulse from the photoelectric conversion element 4.

As described above, since the imaging optical system is not required in the cylindrical rotating body 3, the size of the rotating body can be reduced accordingly.

FIG. 4 shows an example of use of the encoder, and is a system configuration diagram of a drive system using the encoder. An encoder unit 111 is connected to a drive output unit of a drive unit 110 having a drive source such as a motor, an actuator, or an internal combustion engine, or a moving unit of a driven object, and controls an amount of rotation, a rotation speed, a movement amount, a movement speed, and the like. Detect the driving state. The encoder unit 111 is formed by the configuration shown in FIG. The detection output from the encoder unit 111 is an output of a result of pulse counting the output of the photoelectric conversion element 4 by a well-known counter (not shown) in the encoder unit 111, that is, a counter output. Here command means
From 113, a command signal is sent to the control means. Command means 113
May be a well-known control panel (for example, a keyboard) that allows the operator to directly control the driving state of the driving unit, or a memory unit that automatically sends a control signal based on recorded setting conditions. The control unit 112 compares the output of the counter inside the encoder unit 111 with the command signal, and transmits the drive signal to the drive unit 110 so that the commanded rotation angle (or rotation speed) is obtained. By configuring such a feedback system, the driving state instructed by the instructing means 113 can be maintained without being affected by outside. Such a drive system can be widely applied to, for example, a machine tool, a manufacturing machine, an industrial robot, a measuring device, a recording device, and a general device having a drive unit without being limited thereto.

It is assumed that other embodiments described later are also used as shown in FIG.

FIG. 5 (A) is a cross-sectional view showing a state of a connecting portion between the driving means 110 and the encoder unit 111 in FIG. In the figure, reference numeral 3a denotes a fitting part formed integrally with the rotating body 3 on the bottom surface of the cylindrical rotating body 3, and 110a denotes a rotating shaft corresponding to a driving output part of a driving means or a moving part of a driven object. .
The semiconductor laser 1, the photoelectric conversion element 4, and the semi-transmissive mirrors 6, 7 are arranged as constituent elements of a unit U provided at a fixed position. The unit U, which is the detection head, and the cylindrical rotator have a separated structure. As described above, in this embodiment, the connection is performed by fitting the fitting portion integrally provided on the bottom of the rotating body 3 to the rotating shaft.

In the cylindrical grating according to the present embodiment, a shaft fitting member for directly attaching to the rotation detection shaft can be integrally formed by plastic molding or the like, for example, by injection molding or compression molding. The coaxiality of the surface and the fitting part and the fitting accuracy of the shaft can be guaranteed with high accuracy.
The rotation detection accuracy can be improved. As a matter of course, since the mounting member is unnecessary, space saving and cost reduction are easy.

FIGS. 5 (B), (C), and (D) show the second and third embodiments of the present invention, respectively.
3, driving means 110 and encoder unit 1 in the fourth embodiment
FIG. 11 is a cross-sectional view showing a state of a connection portion with 11; In the following description, the same members as those of the previous embodiment are denoted by the same reference numerals. Other configurations, operations, and principles of the second, third, and fourth embodiments are the same as those of the first embodiment, and a description thereof will be omitted.

In the second embodiment of FIG. 5B, a fitting recess is provided on the inner surface of the rotating body 3. In the third embodiment shown in FIG. 5 (C), a fitting projection is provided on the fitting portion 3a of the rotating body 3 to thereby perform fitting. In the fourth embodiment shown in FIG.
The part 3d on the outer surface of the above is directly used as a fitting part. In each case, the fitting portion is formed as one body with the rotating body, and has the same effects as described in the first embodiment.

FIG. 6 is a top view showing a fifth embodiment of the present invention.
Since the measurement principle and operation of this embodiment are the same as those of the first embodiment, the description will be omitted, and only the top view similar to FIG. 3 will be shown.
The difference between the fifth embodiment and the first embodiment is that the semiconductor laser 1
Irradiates light in the y direction, the semi-transparent mirror 6 'reflects this light in the x direction, and the semi-transparent mirror 7' reflects the light reflected from the region 32 in the y direction. Such an arrangement is also possible. Another difference is that the collimator lens system 2 is not provided. In this case, the distance (optical path length) from the light emitting point (divergence origin) of the semiconductor laser 1 to the reflection surface of the region 31 via the semi-transparent mirror 6 'is approximately 1/2 of the radius of curvature of the reflection surface of the rotating body 3. Place it in the same way. Thereby, the reflected light from the region 31 becomes substantially parallel in the xy plane. However, since the light beam reflected from the region 31 is not a parallel light beam in the direction perpendicular to the plane of FIG. 4 (within the xy plane), the light beam incident on the photoelectric conversion element 4 via the second half reflecting mirror 7 ′ in the region 32 is Compared with the first embodiment, the amount of light is reduced by the amount of divergence in the yz plane, and the contrast of the Fourier image on the region 32 is also reduced. These can be made to have almost no effect by reducing the divergence angle of the semiconductor laser 1 or the optical path length to the element 4.

A sixth embodiment of the present invention will be described with reference to FIG. In the sixth embodiment, a reflective V-shaped grooved cylindrical lattice, which will be described later, is used for the cylindrical rotating body 3 ', the semi-transparent mirror 7 is not provided, and two light beams obliquely emitted from the region 32' are used. The fifth embodiment is different from the fifth embodiment in that light is received by two photoelectric conversion elements 4a and 4b and two-phase sine wave pulse outputs having different phases are obtained.

Here, the reflection type V-shaped grooved cylindrical lattice will be described in detail. FIG. 8 is a diagram for explaining the lattice portion.

FIG. 9 and FIG. 10 are diagrams for explaining the light ray action of the grating.

Reference numeral 30a 'denotes a V-shaped groove (hereinafter referred to as "V-groove") and a plane reflecting portion provided between the V-grooves, and 3b' denotes V-groove portions 30b-1 'and 30b.
-2 'are two plane reflecting portions forming the V groove 3b'.

The V grooves 3b 'are arranged at equal intervals on the inner surface of the rotating body 3' by n pitches P (red) in the circumferential direction (nP = 2πrad).
b 'has a width of 1 / 2P (rad), and the two plane reflecting portions 3b-1' and 3b-2 'forming one V-groove have a width of 1 / 4P (ra).
d), and each inclined surface has a value in the range of 45 <θ <90 (deg) with respect to a plane connecting the bottom corner of the V groove and the central axis of the cylinder. θ is set to 75 (deg).

Next, the optical function of the V-groove reflection grating of the present invention will be described with reference to FIG.

A point light source O (here, an equivalent position of the divergence origin of the semiconductor laser 1 in the case where the semi-transmissive mirror 6 'is not provided) is provided in the cylinder, and light rays therefrom enter the reflection surfaces 30a', 30b-1 ', 30b-2'. The result of ray tracing is shown in Fig. 9.
1l to 4l are reflected respectively to 1l 'to 4l'. As can be understood from this drawing, the light reflected by the plane reflecting portion 30a 'is emitted as a substantially parallel light beam in the radial direction of the cylinder, and the plane reflecting portion 30b-1'30b-
The reflected light at 2 'exits in the other direction. Referring now to FIG. 10, the action of the light beam in FIG. 9 will be described for the entire area 31 'irradiated with light. Considering the relationship between the reflection angles of the surfaces 30a ', 30b-1', and 30b-2 'and the effect of diffraction in the region 31', the specularly reflected light (0-order light) from each surface is 1r, 2r and 3r, and ± primary light (broken arrows in the drawing) is generated around the regular reflection light of each of 1r, 2r and 3r as shown in the figure.
(Higher-order diffracted light is also generated, but the intensity is weak, so it is assumed that there is no effect. I will explain this in detail.) Each specularly reflected light and ± 1st-order light generated around it
Although a Fourier image is formed for each, here, a Fourier image generated by 1r of the regular reflection light on the 30a surface and ± primary light generated around the 1r is used.

Here, it is Fourier that the 0th-order light 2r, 3r of the V-groove surfaces 30b-1, 30b-2 and the ± 1st-order light incident on the V-groove surfaces 30b-1 and 30b-2 overlap with the 0th-order light and the ± 1st-order light on the plane reflecting portion 30a. It causes image noise in the image. Therefore, the angle θ of the V-groove is ± 1 at the V-groove in the region of the diffracted light of the ± 1st-order light by the plane grating of 30a
It is necessary to set so as to cause crossover such that the next light overlaps or approaches each other to the center 0th order light. If the angle of each ± 1st order light with respect to the center 0th order light is θ ₁ (unit is deg), the grating pitch is P (unit is red), and the wavelength of light is λ Therefore, in order to prevent the above-mentioned crossover, θ
Is Need to be set in Specifically, as described above, 45 <θ
It is desirable to take a value in the range of <90 (deg).

Returning to FIG. 7, the light beam from the light source unit 1 is incident on the cylindrical grating 3 by the semi-transparent mirror 6. The incident light beam travels in three directions as described with reference to FIGS. 8 to 10, but as described above, the specularly reflected light (0th-order light) and the ± 1st-order light particularly from the grating portion 30a '. If a Fourier image is used, it is possible to form a Fourier image on the second region 32 'by the same operation as in the previous embodiment.

Now, the light and dark lattice image formed on the second region 32 'is reflected by the second region lattice portion. At this time, the light and dark lattice image is reflected by the reflection surface 30a', 30b-1 ', 30
b-2 'is selectively incident. Reflective surface 30b
-1 ', 30b-1' are centered at 1/4 of one pitch, that is, P
Since the specularly reflected light of 30b-1 'is received by the photodetector 4a and the specularly reflected light of 30b-2' is received by the photodetector 4b, two beams having a 90 ° phase difference from each other are received. A sinusoidal pulse is obtained.

The direction of rotation is detected from the two sine wave pulse signals having a 90 ° phase difference, and a counting pulse of 1/4 of the sine wave pitch is obtained. Using the detected rotation direction and the counting pulse, a well-known counter device can be used to obtain a count output taking into account the rotation direction. The method and the device for performing this method are well known and will not be described here. Specifically, if 500 V-grooves are formed inside a cylinder having a diameter of 5 mm, 4,000 count pulses can be obtained by this apparatus.

According to the embodiment, since the cylindrical grating can be manufactured by forming a V-shaped groove without forming a slit, a processing method suitable for mass production such as plastic injection molding or compression molding can be used. Since the production is possible, the cost can be easily reduced as compared with a conventional processing method using a phototriso process.

Also, by setting as described above, two sinusoidal pulse signals having a phase difference with each other can be easily and reliably obtained (because the amount of detected light can be increased as compared with the case of using a normal diffraction grating). It also has advantages.

The two reflected lights from the region 32 'may be folded in the Z direction by mirrors.

FIG. 11 shows a top view of the seventh embodiment of the present invention. In this embodiment, as shown in the figure, the mirrors 7a and 7b reflect the reflected light from the plane reflecting portions 30b-1 'and 30b-2' of the region 32 'in the Z direction, and the plane reflecting portions of the region 32'. The sixth point is that the reflected light from 30a 'is also partially reflected in the Z direction using the semi-transparent mirror 7c, and the three reflected lights are detected to obtain sine wave pulse signals having three phases different in phase. Different from the embodiment.

FIGS. 12 (A), (B), and (C) show a cross-sectional view taken along line AA, BB, and CC in FIG. 11, respectively. Light reflected from the plane reflecting portions 30b-1 ', 30b-2', 30a 'is detected by the photoelectric conversion elements 4a, 4b, 4c, respectively.

Hereinafter, this embodiment will be described. In the above configuration,
FIG. 13 (A) shows a waveform example of the output signal.

 When rotating in the CCW direction, the output waveform of the photoelectric conversion element 4a is a (b for CW), the output waveform of the photoelectric conversion element 4b is b (a for CW), and the output waveform of the photoelectric conversion element 4c is c (CW for CW). Then it becomes like c).

According to the present embodiment, when the lattice rotates P (rad),
In particular, in this case, the phase relationship between the output waveforms a and b has a 90 ° phase difference, so that the output signal has two phases.
Using a and b, these are passed through a well-known comparator circuit to form rectangular waves as shown in FIG. 13 (B), respectively, and the rising and falling portions of each rectangular wave are pulsed as shown in FIG. 13 (C). Obtaining a signal makes it possible to finally obtain eight pulses at a rotation angle of P (rad). Therefore, if the number of lattices provided along the rotation direction of the hollow body is n, then 8 × n
(Pulse / 1 rotation) rotation angle signal can be detected.

In FIG. 13, the output waveform of the V-groove circular lattice having the shape shown in FIG. 8 is shown. At this time, the V-groove width is not ideally 1 / 2P but 6 / 10P.
Alternatively, if the width is slightly narrowed like 4 / 10P, or it is widened and processed over one round, the relationship between the phase differences of the output signals a and b does not become exactly 90 °, The values are slightly shifted. This results in a pulse interval error when the pulse is finally converted into a pulse, which causes inaccuracy.

Therefore, a method for correcting a slight deviation of the 90 ° phase difference on a circuit will be described.

Now, if the V-groove width is processed to be wider than 1 / 2P over the entire circumference of the cylinder, the phase difference between the outputs a 'and b' of the elements 4a and 4b becomes 90 ° or more. The waveforms at this time are shown by a 'and b' in FIG. 14 (A).

Therefore, the amplitude gains of the outputs a and c are adjusted to produce a differential output signal C1 of both, and the amplitude gains of the outputs b and c are similarly adjusted to produce a differential output signal C2. The phase difference between the signals C1 and C2 can be changed to an arbitrary value equal to or smaller than the phase difference between a 'and b' depending on the degree of adjustment of the amplitude gain at this time. Therefore, if the amplitude gain is adjusted according to the width of the V-groove which has become wider than designed, the angle can always be accurately adjusted to 90 °.

A signal as a differential output between the signal c 'and the angular signals a' and b '
The phase difference between C1 and C2 cannot be greater than the phase difference between the original signals a 'and b'. Therefore, when machining the V groove,
It is made a little larger in advance so that if an error occurs in the phase difference, the phase difference must be greater than 90 °. If an error occurs, the amplitude gain is adjusted so that the phase difference between the differential outputs C1 and C2 is smaller than the phase difference between the outputs a 'and b' by the amount of the error.

FIG. 15 is a block diagram showing a circuit configuration for generating the above-mentioned differential output in the present apparatus. 140a, 140b, 140c are amplitude gain adjustment circuits for adjusting the amplitude gain of the output signals from the photoelectric conversion elements 4a, 4b, 4c, respectively, and 141a, 141b are the amplitude gain adjustments of the outputs of the amplitude gain adjustment circuits 140a, 140b, respectively. The differential amplifiers 142a and 142b that generate a differential output with the output of the circuit 141C are the outputs of the differential amplifiers 141a and 141b, respectively.
That is, it is a comparator for converting C1 and C2 into binary pulse signals (referred to as C1 'and C2', respectively) as shown in FIG. 13 (B). The outputs C1 and C2 are counted pulse signals having a shorter period by a known method (FIG. 13 (C)
Is converted to the signal shown in FIG. These are not described here.

For example, the operator adjusts the phase difference so that the operator adjusts the amplitude gain of each of the signals a ', b', and c 'using an oscilloscope or the like while checking the waveforms of C1 and C2 with an oscilloscope or the like so that the signals are adjusted to 90 °. Good. If the V-groove is made smaller than designed, an adder may be used instead of the differential amplifiers 141a and 141b.

As described above, in the present embodiment, three-phase signals are taken, and the phase difference between the other two signals is adjusted using one of the three signals. It is possible to perform more accurate rotation detection.

FIG. 16 shows a top view of the eighth embodiment of the present invention. This embodiment uses a cylindrical rotating body having a grating different from that of the seventh embodiment, and uses semi-transmissive mirrors 7a 'and 7b' having the same reflectance as the semi-transparent mirror 7c instead of the mirrors 7a and 7b. The configuration is the same as that of the seventh embodiment except that signal processing different from that of the seventh embodiment is performed on output signals from the elements 4a, 4b, and 4c, and a description of these similar points is omitted.

Fig. 17 is a view for explaining the form of the lattice of the cylindrical rotating body 3 "in the apparatus. The form of this rotating body is the same as that described in Fig. 8, and the width of the V groove is set to 1 / 2P to 2 / 3P, the width of the plane 30a "provided between the V grooves is 1 / 3P, and the width of the two planes 30b-1" and 30b-2 "forming the V groove is each 1 / 3P each.

In such a lattice, the states 4a, 4b,
Output signal a ″ of each element when light is received by 4c,
FIG. 18 (A) shows a waveform example of b ″, c ″.

In this case, as shown in the figure, the output signal amplitudes of the respective outputs a ", b", and c "are substantially the same, and the phase relationship between the two phases is approximately 120 DEG delayed or advanced.
Each of the phase signals is subjected to rectangular wave processing through a comparator to obtain 3
Two rectangular pulse signals (Fig. 18 (B)),
As shown in FIG. 18 (C), pulse signals are generated at the rising and falling edges of each rectangular pulse signal so that 12 pulses are obtained when the cylindrical lattice rotates by P (rad).

Therefore, if the total number of grids is n, 12 × n in one rotation
(Pulse / 1 rotation) rotation angle signal is obtained.

Therefore, the lattice shape of the cylindrical lattice of the present invention (FIG. 17) makes it possible to use all three of the three-phase signals to increase the number of counting pulses and increase the resolution.

FIG. 19 is a block diagram of a circuit for performing the above processing. 143a, 143b, 143c are amplitude amplifier circuits for amplifying the amplitudes of the outputs a ″, b ″, c ″ from the respective elements, 144a, 144
b and 144c are comparators for outputting output signals from the respective amplitude amplifier circuits 143a, 143b and 143c as rectangular pulse signals as shown in the respective outputs a ₁ ″, a ₂ ″ and a ₃ ″ of FIG. 18B. Reference numeral 145 denotes a pulse generation circuit that generates a pulse at the rise and fall of the output a ₁ ″, a ₂ ″, a ₃ ″ from each comparator to generate the count pulse signal CP shown in FIG. 8C. . The pulse generation circuit 145 also determines the direction and outputs a direction signal DS.
The signal CP is counted by a well-known counter in consideration of the direction signal DS, whereby the rotation amount of the rotating body 3 ″ is detected.

As described above, by using the three-phase output signal, it is possible to obtain a six-fold frequency pulse signal having a higher resolution than a pulse signal having a four-fold frequency of a sine wave pulse signal based on a conventional two-phase output signal.

In each of the embodiments described above, the side of the cylindrical rotating body as the hollow body rotates, and the side where the light source and the photoelectric conversion element are provided, that is, the unit U side is fixed, but may be reversed. In each embodiment, the connection between the rotating body and the rotating shaft is shown in FIGS.
Any of (D) may be used.

Further, in each embodiment, a collimator lens may be provided as needed as in the first embodiment.

The hollow body is not limited to a cylindrical shape, but may be any shape that achieves the principles of the present invention. The V-groove may have an asymmetric V-shape or a shape other than the V-shape. For example, the V-groove may be a V-shaped protrusion.

〔effect〕

As described above, according to the present invention, there is no need to provide an imaging optical system inside the hollow body, and the hollow body can be reduced in size and easy to manufacture.

[Brief description of the drawings]

FIG. 1 is a perspective view of a rotary encoder according to a first embodiment of the present invention, FIG. 2 is a cross-sectional view of the same device, FIG. 3 is a top view of the same device, and FIG. FIGS. 5 (A), 5 (B), (C), and (D) are cross-sectional views showing a state of a connection portion of the first, second, third, and fourth embodiments of the present invention with the driving means of the rotary encoder, respectively. FIG. 6, FIG. 6 is a top view of a rotary encoder of a fifth embodiment of the present invention, FIG. 7 is a top view of a rotary encoder of a sixth embodiment of the present invention, and FIG. 9 and 10 are explanatory views for explaining the light ray action of the grating portion, FIG. 11 is a top view of a rotary encoder according to a seventh embodiment of the present invention, and FIGS. 12 (A) and 12 (B). (C) shows A in FIG.
13 (A), 13 (B), and 13 (C) are waveform examples of respective signals in the same device, and FIGS. 14 (A) and 14 (B) are the same. FIG. 15 is a waveform diagram for explaining the principle of phase correction in the device, FIG. 15 is a block diagram showing a circuit configuration in the device, FIG. 16 is a top view of a rotary encoder according to an eighth embodiment of the present invention, and FIG. FIG. 18 (A), (B), (C) are waveform diagrams of respective signals in the device, and FIG. 19 is a block diagram showing a circuit configuration in the device. 1 Semiconductor laser 3, 3 ', 3 "Cylindrical rotating body 4, 4a, 4b, 4c Photoelectric conversion element 6, 6', 7, 7 'Semi-transparent mirror 30a Slit 30b Reflector 30a ': Planar reflector 3b': V-groove

Claims (5)

(57) [Claims] 1. A hollow body, a grating arranged in the hollow body along a rotation detection direction, and a light irradiating a first area in which the grating is formed from the inside of the hollow body, and a grating in the first area. Light irradiating means for projecting a Fourier image of the lattice of the first region on a lattice of a second region different from the first region of the hollow body by the light reflected at the region, and reflection at the lattice of the second region A rotary encoder having light detection means for receiving the light. 2. The rotary encoder according to claim 1, wherein said lattice has V-shaped grooves or projections periodically arranged on an inner peripheral surface of said hollow body. 3. The rotary encoder according to claim 2, wherein said light detecting means has a plurality of elements for respectively receiving light beams emitted in different directions from said second area. 4. The rotary encoder according to claim 1, wherein said light irradiation means has a reflecting member for directing light to said first area. 5. The rotary encoder according to claim 1, wherein said light detecting means has a reflecting member for directing light emitted from said second area toward a light receiving element.