JPH058427U - Photoelectric encoder - Google Patents

Abstract

(57) [Summary] [Construction] A photoelectric encoder, characterized in that a matrix-shaped island-shaped first grating portion 28 is formed on the first grating 26, and the second grating 30 is a cross-shaped grating orthogonal to each other. . [Effect] It is possible to detect displacement in the X and Y directions over a wide range with a simple configuration.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

  The present invention is a photoelectric encoder, particularly a photoelectric encoder that can detect displacement in two dimensions. Regarding the improvement of the feeder.

[0002]

[Prior art]

  Two parts that move relative to each other, such as various measuring machines, machine tools, and more recently various information machines. Various encoders are used to detect the displacement amount of the material, especially in the non-contact Photoelectric encoders are widely used because they need to detect the unit quantity.   This photoelectric encoder has a main scale and an Index scale is provided, for example through a grid provided on the index scale. To irradiate the main scale with light and then receive the light through the main scale grating. The light is received by the detector and the relative movement amount of the member is detected from the phase change and the like. .

[0003]

[Problems to be solved by the device]

  However, the conventional general photoelectric encoder does not perform linear displacement or rotational displacement. Relative between two members that only measure in one dimension and move relative to each other in two dimensions The displacement could not be detected by a single encoder.

[0004]   The present invention has been made in view of the above-mentioned problems of the prior art, and its purpose is to simplify the configuration. It is easy to use, and is a photoelectric sensor that can detect a wide range of two-dimensional displacement. To provide an encoder.

[0005]

[Means for Solving the Problems]

  In order to achieve the above object, the photoelectric encoder according to claim 1 of the present application is A main scale on which a ricks-shaped island-shaped first lattice is formed; A second lattice that is arranged in parallel so that it can move in a two-dimensional direction relative to each other and is orthogonal to each other in a cross shape. And an index scale with which is formed.

[0006]   Further, in the photoelectric encoder according to claim 2, the first grating is a reflective island grating. The index scale has a transparent cross-shaped second grating and the outer periphery of the second grating. Is provided on the rear surface of the transmissive cross-shaped second grating. An optical element and a light receiving element provided on the back surface of the transmissive third grating. .

[0007]

[Action]

  The photoelectric encoder according to the present invention has an index scale as described above. A cross lattice is provided, while the main scale has a matrix of islands. There is a child. Therefore, the grid in one direction of the cross-shaped second grid is the island-shaped first grid. Corresponds to the row direction of the matrix of and the amount of movement in that direction is detected. Also, the cross The second lattice in the other direction corresponds to the column direction of the matrix of the island first lattice, The amount of movement in that direction is detected.   As described above, according to the photoelectric encoder of the present invention, The movement amount can be detected by one encoder.

[0008]

【Example】

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.   FIG. 1 is a vertical sectional view showing the basic structure of a photoelectric encoder according to an embodiment of the present invention. The drawing is shown, and FIG. 2 is a sectional view taken along line II-II of FIG.

[0009]   In the figure, the main scale 12 of the photoelectric encoder 10 is a moving member. 14 and an index scale 16 is provided on the moving member 18. . Then, the relative movement amount of the moving members 14 and 18 is detected.

[0010]   The lower surface of the index scale 16 in FIG. 1 includes one light emitting element 20 and eight light emitting elements. The light receiving elements 22a, 22b, ... 22h are arranged. Light emitting element 20 and each light receiving The lead wire of the element 22 is fixed to the printed board 24.   The main scale 12 is provided with a first lattice 26 shown in FIG. The child 26 is a matrix-shaped rectangular island-shaped reflection grating portion 28.₁₁, 28₁₂… 28_1n, 28 2₁, 28_{twenty two}… 28_2n, ..., 28_m1, 28_m2, ... 28_mnA cross-shaped reflective grating including Become The arrangement of the lattice portions 28 in the X-axis (row) direction is the pitch P parallel to the Y-axis.₁Lattice of And the arrangement of the lattice portions 28 in the Y-axis (row) direction is a pitch P parallel to the X-axis.₁'Case Make up a child.

[0011]   On the other hand, as is clear from FIG. 4, the index scale 16 has the second grid 30. And third grids 32a, 32b, ... 32h. And the second grating 30 Each of the triangular transmission grating portions 34a, 34b, ... 34d corresponding to the light emitting element 20. It is composed of a cross-shaped transmission grating including. The third lattices 32a, 32b, ... 32h are Each of the light receiving elements 22a, 22b, ...   Therefore, the light L emitted from the light emitting element 20 receives the second grating portions 34a, 34b, ... 3 4d is reflected by the first grating 26, and the reflected light is reflected by the third gratings 32a, 32b, ... The light is received by the light receiving elements 22a, 22b, ... 22h via 32h.

[0012]   As described above, the photoelectric encoder according to the present embodiment is capable of relative movement in the X direction. On the other hand, the second lattice parts 34a, 34b, the first lattice part 28 are arranged in the column direction, and the third case Child parts 32a, 32b, 32c, 32d, light receiving elements 22a, 22b, 22c, 22 d functions as a three-lattice displacement detector. Also, relative movement in the Y direction For the second grid portions 34c, 34d, the first grid portion 28 is arranged in the row direction, The grating portions 32e, 32f, 32g, and 32h serve as three-lattice displacement detectors. To work.

[0013]   That is, as shown in FIG. 5, the three-lattice type displacement detector has three overlapping grids. The amount of displacement is detected by changes (Journal of the optical society of A America, 1965, vol.55, No.4, p373-381).

[0014]   The three-lattice displacement detector shown in FIG. 5 includes a second grating 30 and a third grating arranged in parallel. 32, and a first grating 26 arranged in parallel between the two gratings 30, 32 so as to be relatively movable. The light emitting element 20 arranged on the left side of the second grating 30 in the drawing, and the third grating 32. And a light receiving element 22 arranged on the right side in the figure.   Then, the light emitted from the light emitting element 20 is transmitted to the second grating 30, the first grating 26, and the third grating. The light receiving element 22 reaches the light receiving element 22 via the grating 32, and the light receiving element 22 is connected to each of the gratings 30, 26, 3 The illumination light limited by 2 is photoelectrically converted, and further amplified by the preamplifier 52 to detect the detection signal s. To get

Here, when the first grating 26 moves relative to the second grating 30 and the third grating 32 in the x direction, for example, the illumination light from the light emitting element 20 is shielded by the gratings 30, 26, 32. The amount of light emitted gradually changes, and the detection signal s is output as a substantially sine wave. The pitch P ₁ of the first grating 26 and the wavelength P of the detection signal s correspond to each other, and the relative movement amount of the reference grating 26 is measured from the wavelength of the detection signal s and its division value.

Therefore, by disposing the first grating 26 on the moving member 14 and the second grating 30 and the third grating 32 on the moving member 18, the relative movement amounts of both moving members can be detected. In this embodiment, the grid portions 28 of the first grid 26 are arranged in the X-axis direction so as to be parallel to the Y-axis and have a pitch P _1. The grid portions 28 are arranged in the Y-axis direction in the X-axis direction. To form a grating having a pitch P ₁ 'parallel to.

Further, the grating portions 34a and 34b of the second grating 30 are formed with gratings parallel to the Y axis and having a pitch P ₂ and the grating portions 24c and 34d are formed with gratings parallel to the X axis and having a pitch P ₂ ′. Has been formed. Furthermore, the third lattice 32a has an Ax phase lattice, the third lattice 32b has an Ax 'phase lattice, the third lattice 32c has a Bx phase lattice, and the third lattice 32d has a Bx' phase lattice. Lattices are formed in parallel with each other at a pitch P ₃ in parallel with the Y-axis. The third lattice 32e has an Ay phase lattice, the third lattice 32f has an Ay ′ phase lattice, and the third lattice 32g has a By phase. In the grating and the third grating 32h, By ′ phase gratings are formed in parallel with the X axis at a pitch P ₃ ′.

Therefore, when Ax = 0 °, Ax ′ = 180 ° (1 / 2P ₃ different) Bx = 90 ° (1 / 4P ₃ different) Bx ′ = 270 ° (3 / 4P ₃ different) with respect to Ax ) also, when Ay = O °, different Ay '= 180 ° (1 / 2P _3' relative to Ay) By A = 90 ° (1 / 4P ₃ 'differs) By A' = 270 ° ₍₃ / 4P 3 ' Different) are graduated.

[0019]   As a result, from the light receiving elements 22a, 22b, 22c and 22d, respectively, π / 2 It is possible to obtain signals of Ax phase, Ax 'phase, Bx phase, and Bx' phase whose phases are shifted from each other, The Ax phase output which is differential amplitude amplified from the Ax phase-Ax 'phase is also referred to as the Bx phase-Bx' phase. A Bx phase output with differential amplitude amplification is obtained. Then, the Ax phase output and the Bx phase output When the discrimination of the relative movement direction of the scale in the X direction is performed based on the phase shift direction of In addition, the detection signal is electrically divided to detect displacement with high resolution. .   On the other hand, from the light receiving elements 22e, 22f, 22g, and 22h, each is π / 2. Signals of Ay phase, Ay ′ phase, By phase and By ′ phase which are out of phase can be obtained, The phase discrimination in the Y direction and the relative movement distance of the moving members 14 and 18 are detected in the same manner as the direction. Can be issued.   As described above, according to the photoelectric encoder according to the first embodiment, the X direction and the Y direction The moving direction and the moving distance of the direction can be detected.

Further, in the present embodiment, the pitch of the column-direction lattice portion 28 for detecting movement in the X direction and the pitch of the row-direction lattice portion 28 for detecting movement in the Y direction are provided differently. That is, the pitch in the column direction is a relatively coarse pitch P ₁ , and high-speed reading of movement in the X direction is possible. On the other hand, the pitch in the row direction is engraved with a relatively fine pitch P ₁ ′, which enables high-resolution reading of movement in the Y direction. In this way, it is possible to determine the respective pitches according to the movement characteristics of the moving member, and furthermore, the formation of the grating according to the pitch can be performed extremely accurately by the same manufacturing method as the conventional one.

It is preferable to configure the pitch as follows, for example. P ₁ = 40 μm (light portion length = dark portion length = 20 μm) P ₂ = 160 μm (bright portion length = 40 μm, dark portion length = 120 μm) P ₃ = 80 μm (bright portion length = dark portion length = 40 μm) P ₁ ′ = 20 μm (bright portion length = Dark part length = 10 μm) P ₂ '= 80 μm (bright part length = 20 μm, dark part length = 60 μm) P ₃ ' = 40 μm (bright part length = dark part length = 20 μm) Thus, the pitch of the second grating is larger than the pitch of the first grating. By increasing the length of the light transmission part to be equal to or less than the pitch of the first grating, the independence (incoherency) between the illumination light transmitted through the second grating is improved, and the detection signal is increased. The SN ratio becomes higher. Therefore, signal processing becomes easy, and highly accurate displacement detection becomes possible.

It is also preferable that the pitch structure be as follows. P ₁ = 100 μm (light portion length = dark portion length = 50 μm) P ₂ = 400 μm (bright portion length = 100 μm, dark portion length = 300 μm) P ₃ = 200 μm (bright portion length = dark portion length = 100 μm) P ₁ ′ = 40 μm (bright portion length = Dark part length = 20 μm) P ₂ '= 160 μm (bright part length = 40 μm, dark part length = 120 μm) P ₃ ' = 80 μm (bright part length = dark part length = 40 μm)

Further, it is preferable to configure the pitch as follows, for example. P ₁ = 20 μm (light portion length = dark portion length = 10 μm) P ₂ = 20 μm (bright portion length = dark portion length = 10 μm) P ₃ = 20 μm (bright portion length = dark portion length = 10 μm) P ₁ ′ = 10 μm (bright portion length = dark portion length) = 5 μm) P ₂ '= 10 μm (light portion length = dark portion length = 5 μm) P ₃ ' = 10 μm (bright portion length = dark portion length = 5 μm) In this way, the pitches of the first grating, the second grating, and the third grating are made equal. Further, assuming that the lattice spacing between the movable scale 26 and the index scale 16 is d, in this example, P ₁ = 20 μm> P ₁ '= 10 μm. Therefore, the lattice spacing d between the movable scale 26 and the index scale 16 is d ≧ P _By setting ₁ ² / 2λ, it is possible to realize an XY encoder whose output hardly fluctuates in response to fluctuations in the lattice spacing d. When P ₁ = P ₁ ′, either _one may be adopted. The features of this configuration are: (1) When 1 pitch P _{1 is} sent in the X direction, the output signal is output by 2 pitches P ₁ and an optical split signal is obtained, so that an electrical split circuit is easily constructed. (2) Since it is tolerant of fluctuations in the lattice spacing d, it is suitable for a fine pitch system in which P ₁ or P ₁ ′ is 40 μm or less, for example.

In addition, it is also preferable that the pitch configuration is as follows. P ₁ = 40 μm (light portion length = dark portion length = 20 μm) P ₂ = 80 μm (bright portion length = dark portion length = 40 μm) P ₃ = 80 μm (bright portion length = dark portion length = 40 μm) P ₁ ′ = 10 μm (bright portion length = dark portion length) = 5 μm) P ₂ '= 10 μm (bright part length = dark part length = 5 μm) P ₃ ' = 10 μm (bright part length = dark part length = 5 μm) With this configuration, when one pitch is sent in the X-axis direction, 1 pitch P An output signal of ₁ is obtained. By sending 1 pitch P ₁ 'in the Y-axis direction, an output signal of 2 pitches P ₁ ' is obtained. Therefore, the X-axis direction has a low resolution and is suitable for high-speed detection, and the Y-axis direction has a high resolution and is suitable for low-speed detection.

[0025]   Further, in the present invention, the first grating 26 can be formed over a wide range. It is also possible to broaden the detection.   Further, the shape of the first lattice 26 is the phase of the main scale and the index scale. It can be arbitrarily determined in consideration of the moving distance and the like.   In addition, the matrix-shaped island-shaped grating 28 provided on the main scale is used as a transmission part. However, it is also possible to configure the portion 29 that is not the island lattice as the reflecting portion.

[0026]

[Effect of device]

  As described above, according to the photoelectric encoder of the present invention, the main scale Matrix with island-shaped first lattice, and a grid orthogonal to the index scale. Since the child is provided in a cross shape, it is possible to detect displacement in X and Y directions in a wide range with a simple configuration. It becomes possible to trace.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a schematic configuration of a photoelectric encoder according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of an arrangement of light emitting elements and light receiving elements of the photoelectric encoder according to the embodiment.

FIG. 3 is an explanatory diagram of a main scale (first grating) of the photoelectric encoder according to the embodiment.

FIG. 4 is an explanatory diagram of index scales (second grating and third grating) of the photoelectric encoder according to the embodiment.

FIG. 5 is an explanatory diagram of a movement detection principle of the photoelectric encoder according to the embodiment.

[Explanation of symbols]

10 Photoelectric encoder 12 Main scale 16 Index scale 20 light emitting element 22 Light receiving element 26,126 First grid 30 second grid 32 Third grid

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Creator Shingo Kuroki             165 Sakado, Takatsu-ku, Kawasaki City, Kanagawa Stock             Company Mitutoyo Development Laboratory

Claims (2)

[Scope of utility model registration request] 1. A main scale having island-shaped first lattices formed in a matrix and a second lattice arranged in parallel so as to be movable relative to the main scale in a two-dimensional direction, and forming a cross-shaped orthogonal lattice. An optoelectronic encoder including: an index scale. 2. The encoder according to claim 1, wherein the first grating comprises a reflective island grating, the index scale has a transmissive cross-shaped second grating, and a transmissive element provided on the outer periphery of the second grating. An optoelectronic encoder characterized in that an expression third grating is provided, a light emitting element is provided on a back surface of the transmission type cross-shaped second grating, and a light receiving element is provided on a back surface of the transmission type third grating.