JP2012181018A - Movement information measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a movement information measuring device which allows a signal from a curved surface of a mobile body to have reduced signal amplitude loss due to defocusing, suppressing reduction of detection accuracy of movement information.SOLUTION: A movement information measuring device includes a light source, a mobile body having a curved surface in the direction of movement, and a photodetector which receives condensed reflected light beams or transmitted light beams from the curved surface. The curved surface is provided with a plurality of curvatures in the direction of movement.

Description

  The present invention relates to a movement information measuring device for measuring a relative displacement amount and a relative speed of a moving body as movement information of the moving body.

  As a method for detecting the amount of displacement of the moving body, the light beam reflected from the surface of the moving body is received by a photodetector, and the position of the moving body is determined based on the movement of the reflected light beam accompanying the movement of the moving body. There is a way to detect. Due to the reflectance distribution in the light irradiation area on the surface of the moving body and surface scattering, an intensity distribution is generated in the reflected light on the photodetector, and the intensity distribution of the reflected light on the detector surface also moves as the moving body moves. Therefore, the movement amount of the moving body is detected by detecting the movement of the reflected light intensity distribution by the photodetector. In order to further improve the position detection accuracy, Patent Document 1 discloses a method of increasing the position detection accuracy by forming a concave surface on the surface of the moving body and utilizing the imaging action of the concave surface of the moving body surface.

  Hereinafter, the position detection apparatus described in Patent Document 1 will be described with reference to FIG. FIG. 13 is a diagram illustrating the configuration of the position detection device described in Patent Document 1. An antireflection coating film 1205 is applied to the surface of the moving body 1204 moving in the direction perpendicular to the paper surface, and a reflecting surface coating film is applied to the concave surface portion 1206 which is a member having a light collecting function. A concave shape portion 806 having a light condensing function is provided at a reference position of the moving body 1204, and the measuring device 1201 is fixed at a specific position.

  When the concave shape portion 1206 on the surface of the moving body 1204 moves to a specific position with respect to the position detection device 1201 facing the concave shape portion 1206, the light from the light emitting unit 1202 is reflected on the surface of the concave shape portion 1206. Reflected by. On the surface of the moving body 1204 excluding the concave shaped portion 1206, light is not reflected by the antireflection coating film 1205.

  In this way, the light reflected by the concave-shaped portion 1206 is collected, guided to the light receiving unit 1203, and a change in voltage corresponding to the amount of received light is detected by photoelectric conversion inside the measuring device 1201, and this is received as a signal. The position of the moving body 1204 is detected by a circuit. As described above, by providing the concave surface portion 1206 having a light collecting function on the surface of the moving body 1204, the diffusion of reflected light can be reduced and the position of the moving body 1204 can be detected with high accuracy.

Japanese Unexamined Patent Publication No. 63-249002

  However, the position detection device disclosed in Patent Document 1 has the following problems. That is, the positional relationship between the measuring device 1201 and the moving body 1204 in the z-axis direction is such that the light beam emitted from the light emitting unit 1202 is focused on the surface of the light receiving unit 1203 by the concave shape portion 1206 on the surface of the moving body 1204. Is set to Therefore, if the displacement of the moving body 1204 in the z-axis direction or the displacement of the moving body 1204 in the z-axis direction occurs when the measuring device 1201 is disposed, the light beam on the light receiving unit 1203 is defocused. It becomes a state.

  As a result, the detection signal amplitude is lowered, and as a result, the position detection accuracy is lowered. In view of such a problem, an object of the present invention relates to a signal from a curved surface of a moving body, which can reduce a decrease in signal amplitude due to defocusing and can suppress a decrease in detection accuracy of movement information. It is to provide a measuring device.

  In order to achieve the above object, an invention according to the present application includes a light source, a moving body that is irradiated with the light source and has a curved surface in a moving direction, and a light receiving element that receives the reflected or transmitted light collected from the curved surface. The curved surface has a plurality of kinds of curvatures in the moving direction.

  ADVANTAGE OF THE INVENTION According to this invention, regarding the signal from the curved surface of a moving body, the reduction | decrease of the signal amplitude by defocus can be reduced, and the fall of the detection accuracy of movement information can be suppressed.

It is a figure which shows the structure of the displacement measuring apparatus which is the 1st Embodiment of this invention. (A) is a figure which shows the shape of the concave surface formed in the moving body surface in 1st Embodiment, (b) is explanatory drawing about the distance fluctuation | variation in a Z-axis direction. It is a figure shown about the magnitude relation of the curvature of the movable body surface in a 1st embodiment, (a) is the curvature of an outer edge part smaller than the curvature of a center part, when (a) is smaller curvature of the outer edge part than the curvature of a center part. This is the case when the curvature is large. (A) is a figure which showed a mode that the optical pattern image in 1st Embodiment passes, (b) is a figure which shows the sum signal of each photodiode, (c) is a figure which shows a differential output. It is the figure which showed the detection voltage value with respect to the distance fluctuation | variation in the Z-axis direction in 1st Embodiment. It is a figure which shows the structure of the displacement measuring apparatus in 2nd Embodiment. It is a figure which shows the structure of the displacement measuring apparatus in 3rd Embodiment. It is a figure which shows the structure of the speed measurement apparatus in 4th Embodiment. (A) is a figure which shows the signal obtained in advance by the photodiode array group in 4th Embodiment, (b) is a figure which shows the position of the mobile body at that time, (c) is a delay in a photodiode array group (D) is a figure which shows the position of the moving body at that time. It is a block diagram of the process which gives time delay to the data in 4th Embodiment. It is a figure which shows the structure of the displacement and speed measurement apparatus in 5th Embodiment. It is a conceptual diagram which shows the apparatus structure which replaced with the reflective curved surface and used the transmissive curved surface. It is a figure which shows the speed measuring apparatus of a prior art example.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

<< First Embodiment >>
The configuration of the displacement measuring apparatus according to this embodiment will be described with reference to FIG. The moving body 102 moves in the Y-axis direction, which is the moving direction, and is irradiated with irradiation light that becomes a divergent light beam from the light source 101 that emits light of wavelength λ. On the surface of the moving body 102, a concave surface 103 having a length C in the moving direction cross section is formed. The divergent light beam is reflected and collected by the concave surface 103 and is formed into an optical pattern image 106 on a photodiode array as a light receiving element that receives the reflected light from the concave surface 103.

  The photodiode array includes a photodiode array 104 arranged with a width Pd / 2 and a distance Pd with respect to the moving direction of the moving body 102, and Pd / 2 with respect to the moving direction of the moving body in the same configuration. A photodiode array 105 is provided that is shifted. The overall configuration of the displacement measuring apparatus according to the present embodiment has been described above.

(Curved surface of moving body)
Next, the concave surface 103 will be described in detail as an example of the curved surface portion formed along the moving direction on the surface of the moving body 102 that is a feature of the present invention. As shown in FIG. 1, the concave surface 103 is curved only in the moving direction and is not curved in the direction orthogonal to the moving direction. However, the concave surface 103 is also provided with a curved surface in the direction orthogonal to the moving direction. It is also good. Here, the magnitude of the curvature of the concave surface 103 which is a curved surface portion is opposite to the magnitude of the curvature radius (the curvature is 1 / R when the curvature radius is R), and the curvature is large when the curvature radius is small. To do.

  FIG. 2A is a diagram illustrating the curvature of the concave surface formed on the surface of the moving body 102. The concave surface 103 has a shape in which the curvature of the central portion 201 and the curvature of the outer edge portion 202 are different, and relative distance variation fluctuation in the z-axis direction between the moving body 102 and the detector on which the light source 101 and the photodiode array are mounted. It is determined in association with. Moreover, the shape of the center part 201 of the concave surface 103 and the intermediate part 203 of the outer edge part 202 is formed so that the shape of the center part 201 and the shape of the outer edge part 202 are continuously connected.

FIG. 2B is a diagram illustrating a relative distance variation between the moving body 102 and the detector in the z-axis direction. When the moving body 102 has a variation of ΔZ in the z-axis direction, or when the mounting tolerance in the Z-axis direction between the moving body surface and the displacement detection device is ± ΔZ / 2 with respect to the center value. Think. In this case, the relationship between the radius of curvature R1 of the concave central portion 201 and the radius of curvature R2 of the outer edge portion 202 is expressed by the following conditional expression.
| R1-R2 | ≧ ΔZ Formula-1
The dimension C of the cross section in the moving direction of the concave surface 103 is determined so as to satisfy the following conditional expression from the curvature radius R1 of the central portion 201 and the curvature radius R2 of the outer edge portion 202.

C ≦ (R1 + R2) × √ (λ / | R1-R2 |) Formula-2
Here, the derivation of Equation-2 will be described with reference to FIG. 12, replacing the reflective type with the transmissive type. In the present invention, in addition to using the reflected light from the curved surface portion of the moving body, transmitted light from the curved surface portion of the moving body may be used.

  When the center wavelength of the light source 101 is λ, the focal depth of the lens corresponding to the concave surface 103 is d, and the numerical aperture is NA, the following equation is generally established. That is, d = λ / NA / NA and NA = n × sin θ. Here, regarding n, n = 1 as the refractive index of air. It is assumed that the depth of focus d is equal to | R1−R2 |, and the NA is NA = C0 / 2 / [(R1 + R2) / 2] where the dimension of the cross section in the moving direction is C0, C0 = (R1 + R2) × √ (λ / | R1-R2 |).

  Here, since it is not preferable to further increase the peripheral region having the radius of curvature R2 with respect to the central region having the radius of curvature R1, the dimension C of the cross section in the moving direction is preferably C0 or less, and Equation-2 is derived. .

  According to the present embodiment, by disposing the detector between the moving body between R1 and R2, even if the relative distance between the moving body and the detector varies | R1-R2 | It is possible to reduce a decrease in signal amplitude due to defocusing and suppress a decrease in position detection accuracy.

  Here, it is generally preferable that an intermediate portion between the central portion 201 (curvature radius R1) and the outer edge portion (curvature radius R2) in the curved surface portion is set so that the curvature continuously changes. You may give a discontinuous curvature in an intermediate part.

(Multiple types of curvature on the curved surface of a moving object)
Next, the magnitude relationship between the curvature radius R1 of the central portion 201 of the concave surface 103 and the curvature radius R2 of the outer edge portion 202 will be described with reference to FIG. FIG. 3A is a diagram showing an optical path of a light beam reflected and collected by the concave surface 103 when the curvature radius R2 of the outer edge portion 202 is smaller than the curvature radius R1 of the center portion 201. FIG. When the relative distance between the moving body 102 and the detector in the z-axis direction becomes small, the light beam reflected from the outer edge portion 202 forms an image. On the other hand, when the relative distance between the moving body 102 and the detector in the z-axis direction increases, the light beam reflected from the central portion 201 forms an image. When the relative distance between the moving body 102 and the detector in the z-axis direction is an intermediate distance in the above range, the light beam reflected from the intermediate portion forms an image.

  FIG. 3B is a diagram illustrating an optical path of a light beam reflected and collected by the concave surface 103 when the curvature radius R2 of the outer edge portion 202 is larger than the curvature radius R1 of the central portion 201. When the relative distance between the moving body 102 and the detector in the z-axis direction becomes small, the light beam reflected from the central portion 201 forms an image. When the relative distance between the moving body 102 and the detector in the z-axis direction increases, the light beam reflected from the outer edge portion 202 forms an image. When the relative distance between the moving body 102 and the detector in the z-axis direction is an intermediate distance in the above range, the light beam reflected from the intermediate portion forms an image.

  Thus, the concave surface 103 has a region contributing to image formation corresponding to the relative distance between the moving body 102 and the detector in the z-axis direction.

  Hereinafter, regarding the moving body and the displacement detector, a specific numerical value will be taken as an example to describe the length C of the concave surface. In general, in a position detection application such as an encoder, the mounting accuracy in the z-axis direction of the detector is required to be about ΔZ = ± 1 mm with respect to the center value with respect to a scale that is a moving body. At this time, | R1−R2 | ≧ 2 mm, and | R1−R2 | = 2 mm. Assuming that the installation position of the detector is 2 mm from the moving body 102 in the z-axis direction, the dimension of the cross section in the moving direction of the concave surface 103 is C ≦ 90 μm from Equation-2. Since the amount of received light detected by the photodiode array of the detector depends on the size of C, C = 90 μm is preferable.

  As a specific example, when a red LED is used as a light source, λ is 650 nm, and assuming | R1-R2 | is 2 mm, R1 is 3.5 mm, R2 is 1.5 mm, and C is 90 μm. . The same applies when R1 is 1.5 mm and R2 is 3.5 mm.

  In addition, when the moving body is a flexible body such as a resin film, the z-axis of the detector with respect to the resin film that is the moving body due to a shake in the z-axis direction of the resin film accompanying the displacement in the moving direction of the resin film. The mounting accuracy in the direction is required to be about ΔZ = ± 2 mm with respect to the center value. At this time, if the installation position of the detector is 5 mm in the z-axis direction from the moving body 102, the dimension of the cross section in the moving direction of the concave surface 103 is C ≦ 150 μm from Equation-2. Since the amount of received light depends on the size of C, C = 150 μm is preferable. Examples of the resin film mentioned here include, but are not limited to, a transfer belt used in a copying machine or a laser beam printer.

When the moving body is a flexible body such as a resin film, when a red LED is used as the light source, if λ is 650 nm and | R1-R2 | is 4 mm, R1 is 8 mm, R2 is 4 mm, and C is 150 μm. . The same applies when R1 is 4 mm and R2 is 8 mm.
In the above, the concrete numerical example was demonstrated and demonstrated about the concave surface 103 shape formed in the mobile body 102 surface.

(Displacement of optical pattern image on photodiode array)
Next, the principle of displacement of the optical pattern image 106 will be described with reference to FIG. The optical path length from the light source emitting unit 101 mounted on the detector surface to the concave surface 103 on the surface of the moving body 102 is L1, and the optical path length from the concave surface 103 to the condensing position on the photodiode array is L2. At this time, the relationship between the moving amount of the light beam imaged on the moving body 102 and the light receiving surface is expressed by moving body: light beam on the light receiving portion = 1: (L1 + L2) / L1. In the example shown in FIG. 1, the optical path length L1 from the light emitting point on the light source 101 to the surface of the moving body 102 is equal to the optical path length L2 from the moving body 102 to the imaging position on the photodiode array.

  Therefore, the relationship between the moving body 102 and the amount of movement of the imaging position in the y-axis direction is moving body: light source emission region image = 1: 2. Based on the above principle, the pattern image 106 formed on the surface of the photodiode array moves as the moving body 102 moves. The relationship between the displacement amount of the moving body 102 and the displacement amount of the optical pattern image 106 formed on the surface of the photodiode array has been described above.

(Displacement detection method)
Hereinafter, the moving body displacement amount detection method will be described in detail. First, the configuration of the photodiode array and the signal detection method will be described. An optical pattern image 106 is formed on the photodiode array by the concave surface 103 of the moving body 102. The optical pattern image 106 is photoelectrically converted by the photodiode array, and the one-dimensional light intensity is converted into a voltage value. The detection voltage value V1 of the photodiode array 104 is determined together with the spatial filter action by taking the sum of the detection voltage values of the plurality of photodiodes forming the photodiode array 104.

  Similarly, the detection voltage value V2 of the photodiode array 105 is determined together with the spatial filter action by taking the sum of the detection voltage values of the plurality of photodiodes forming the photodiode array 105. And the displacement measuring device outputs the voltage value at a certain time from (V1-V2) by the differential of both photodiode array outputs.

  Next, a method for detecting the displacement amount of the moving body 102 from the movement of the optical pattern image 106 on the photodiode array accompanying the movement of the moving body 102 will be described. FIG. 4 shows the movement of the optical pattern image 106 on the photodiode array accompanying the movement of the moving body 102 and the time change of the detection voltage value detected by the photodiode array. FIG. 4A is a diagram for explaining how the optical pattern image 106 passes through the photodiode array 104 and the photodiode array 105.

  The optical pattern image 106 passes through the photodiode array 104 and the photodiode array 105 that are alternately arranged in the Pd cycle. FIG. 4B is a diagram illustrating the voltage value V1 and the voltage value V2 detected by the photodiode array as the optical pattern image 106 moves. A solid line represents a change in voltage value detected by the photodiode array 104 as the optical pattern image 106 moves. Since the photodiode array 104 has the photodiode array 105 sandwiched therebetween, as shown in FIG. 4B, a jump output voltage value V1 is obtained.

  A broken line represents a change in voltage value detected by the photodiode array 105 accompanying the movement of the light source pattern image 106. Similarly, since the photodiodes are arranged in a staggered manner, V2 also obtains a jumpy output voltage value. FIG. 4C is a diagram illustrating a detection voltage value obtained by taking the differential output (V1−V2) of the photodiode 104 and the photodiode 105 with the movement of the optical pattern image. Since V1 and V2 are convex waveforms whose phases are shifted by 180 degrees as shown in FIG. 4B, a signal waveform of one cycle can be obtained by taking a differential as shown in FIG. 4C.

  Therefore, the amount of movement of the optical pattern image 106 on the photodiode array can be detected by counting the number of cycles of the output voltage change detected by the detector as the moving body 102 moves. Thus, the displacement amount of the moving body can be detected based on the moving body 102 and the detected movement amount of the optical pattern image 106 described above. The displacement measuring apparatus using the light source light emitting region image formed by the concave surface 103 of the moving body 102 has been described above.

  In FIG. 5, a solid line represents a detection voltage value with respect to a change in the distance (Gap) in the Z-axis direction between the moving body surface and the displacement detection device when the concave surface 103 of the present invention is used for the moving body 102. In addition, a detection voltage value with respect to a change in the distance in the Z-axis direction between the moving body surface and the displacement detection device when a concave surface having an ideal curvature is used is indicated by a broken line. As Gap approaches the curvature of the concave surface with the ideal curvature, the signal amplitude becomes closer.

  However, the signal amplitude can be increased by about 50% compared to a concave surface having an ideal curvature over a wide range excluding that region. In this way, it is possible to suppress a decrease in signal amplitude due to defocus caused by a gap offset / variation or the like, and to improve position detection accuracy due to a gap variation.

  As described above, according to the present embodiment, the concave surface 103 forms an image of the light flux corresponding to the relative distance from the detector in the range of the relative distance variation ΔZ between the moving body 102 and the detector in the z-axis direction. Can have an area. In other words, the concave surface 103 becomes a curved surface having a progressive focal point or multiple focal points over an interval of ΔZ, so that a decrease in signal amplitude due to defocusing of the light beam on the light receiving surface due to fluctuation is prevented and a decrease in detection accuracy is suppressed.

  According to this embodiment, by providing only one curved surface portion formed along the moving direction in the moving direction, this curved surface portion can be used to detect the absolute value of the position in the moving direction.

<< Second Embodiment >>
The displacement measuring apparatus of this embodiment is demonstrated using FIG. In the present embodiment, a plurality of concave surfaces 103 are periodically provided on the surface of the moving body 102 in the displacement measuring apparatus described in the first embodiment. The period Pl of the concave surface 103 corresponds to the distance between the centers of the light receiving areas adjacent to the moving direction of the moving body, that is, the period Pd of the photodiode array, in the detector having a plurality of light receiving areas. Look at the conditional expression.

Pl = [L1 / (L1 + L2)] × Pd × k Equation-3
k is a positive integer. This means that the optical pattern image 106 formed by the plurality of concave surfaces is formed by an integral multiple of the arrangement period Pd of the photodiodes to be added and detected. When L1 = L2 and k = 1, P1 = Pd / 2. The period Pl of the concave surface 103 is
The value is equal to or slightly larger than C shown in FIG. 12, for example, Pl = 100 μm.

  According to this embodiment, the optical pattern image 106 is detected by a plurality of photodiodes, and the signal voltage can be increased by increasing the output voltage value of the photodiode array, which is the added voltage value. In FIG. 6, the optical pattern image 106 is formed so that the interval Pe of the optical pattern image 106 is twice the interval (Pe = 2 × Pd) of the arrangement period Pd of the photodiode array. Since the principle of displacement measurement has been described in the first embodiment, a description thereof will be omitted.

<< Third Embodiment >>
The displacement measuring apparatus which is this embodiment is demonstrated using FIG. In the present embodiment, a plurality of light emitting portions of the light source in the displacement measuring apparatus described in the second embodiment are provided, and the arrangement period Pe of the optical pattern image 106 associates the array period Pd of the photodiode array with the imaging magnification. It arrange | positions so that it may become the following values.

Pe = L1 / [L2 / (m × Pd)] Formula-4
m is a positive integer, which is smaller than the number of photodiodes forming the in-phase photodiode array to be added and detected. In FIG. 7, m ≦ 3. Here, m = 1, L1 = L2, and the concave surface 103 on the surface of the moving body 102 causes the interval Pe of the optical pattern image 106 to be equal to the photodiode array period Pd (Pe = Pd) on the photodiode array. Form an image. Thus, the optical pattern image 106 by each light source is generated on the plurality of photodiodes to be added and detected.

  Therefore, the output voltage value of the photodiode array, which is the added voltage value detected by the plurality of photodiodes, can be increased, and the signal amplitude can be increased. Since the principle of displacement measurement has been described in the first embodiment, a description thereof will be omitted.

<< Fourth Embodiment >>
A measurement apparatus according to this embodiment that measures the speed of a moving body using the displacement measurement apparatus described in the first to third embodiments will be described with reference to FIG. The speed measuring device in this embodiment includes a plurality of light emitting units 801, a photodiode array group 802, and a photodiode array group 803. The photodiode array group 802 includes a photodiode array 804 and a photodiode array 805 for differential detection.

  The photodiode array group 803 includes a photodiode array 806 and a photodiode array 807 for differential detection. Each photodiode array group is spaced apart by a distance D. The periodic optical pattern image 106 generated on each photodiode array group is photoelectrically converted by the photodiode array, and the one-dimensional light intensity is converted into a voltage value.

  Then, the detection voltage value V1 of the photodiode array 804 is determined as the sum of the plurality of photodiode detection voltage values forming the photodiode array 804. Similarly, the detection voltage value V2 of the photodiode array 805 is determined as the sum of the plurality of photodiode detection voltage values forming the photodiode array 805. The photodiode array group 802 outputs (V1-V2) as a voltage value at a certain time. Similarly, the photodiode array group 803 outputs a voltage value at a certain time.

(Movement speed detection)
Next, a detection method for detecting a movement speed as movement information will be described. Assume that the moving body 102 is moving in the Y-axis direction. At this time, a displacement signal due to the movement of the optical pattern image 106 is detected in advance by the photodiode array group 802. Subsequently, a displacement signal due to the movement of the optical pattern image 106 at the same position is detected by the photodiode array group 803 after being delayed by a time depending on the photodiode array group interval D and the speed of the moving object.

  The speed detection method will be specifically described with reference to FIG. FIG. 9A shows variation data P1 of the detection output that is detected in advance by the photodiode array group 602 and that accompanies the movement of the moving body during a certain time. FIG. 9B is a diagram showing the position of the moving body at time t1 during the P1 data acquisition time. FIG. 9C shows detection output variation data P2 that is detected by the photodiode array group 603 with respect to the photodiode array group 602 and that is associated with the movement of the moving body during a certain time.

  FIG. 9D is a diagram showing the position of the moving body at time t2 during the P2 data acquisition time. From time t1 to time t2, the moving body 102 moves by a distance D / {(L1 + L2) / L1}. FIG. 10 is a block diagram of a process for giving a predetermined time delay to data. The detected output fluctuation data P1 and the detected output fluctuation data P2 are compared with voltage values with respect to time by a comparator 701.

  Here, when the optimum time delay amount T = t2-t1 of the data is given to the detected output fluctuation data P1, the intensity fluctuation data with respect to the time of each photodiode array group matches as a result of the comparison by the comparator 701. . If they do not match, the speed detection circuit gives a correction value for the amount of time delay to the time delay circuit. Then, the comparator 701 performs comparison again using the detected output fluctuation data P1 to which the corrected time delay amount is given.

The speed detection circuit determines the measurement time difference T by the loop. Then, from the photodiode array group interval D, the velocity V of the moving body 102 can be obtained using the following relational expression-7.
V = D / T / {(L1 + L2) / L1} Formula-7
For example, even if the shape of the concave surface 103 formed on the surface of the moving body 102 is uneven and the detected signal amplitude varies for each cycle, the speed detection method can detect the speed. Can do. In the present embodiment, the example in which the velocity measuring device is configured using the displacement measuring device in the third embodiment as a basic system has been described. However, the present invention is not limited to this, and the displacement measuring device in the first and second embodiments is used. A speed measuring device may be configured.

  Further, the photodiode array configuration is not limited to the differential detection type photodiode array configuration as described in the first to third embodiments. Furthermore, as shown in FIG. 9, the photodiode array groups are not arranged on the same substrate, and two displacement measuring devices described in the first to third embodiments may be arranged at a predetermined distance D apart. good. However, the velocity calculation formula in this case is obtained by V = D / T from the passage time T at the center interval D of the photodiode group of the displacement measuring device.

  In the present embodiment, instead of detecting the relative speed based on the passing time of the moving body that passes the predetermined distance interval described above, the relative speed can also be detected based on the displacement amount of the moving body in the predetermined time.

<< Fifth Embodiment >>
The displacement measuring apparatus which is this embodiment is demonstrated using FIG. FIG. 11 shows the displacement measuring apparatus described in the second embodiment with a concave surface 1104 in which the value of C given by Equation-2 is the diameter, the radius of curvature of the inner peripheral portion is R1, and the radius of curvature of the outer peripheral portion is R2. These are periodically formed on the surface of the moving body 102. The detector includes a photodiode array 1102 and a photodiode array 1103 for detecting a displacement amount in the X-axis direction in addition to the photodiode array 104 and the photodiode array 105 for detecting a displacement amount in the Y-axis direction.

  The arrangement period of the concave surface 1104 is a period given by Formula-3 in both the X-axis direction and the Y-axis direction. The optical pattern image 1101 obtained as a result is generated like a spotted pattern in the X-axis and Y-axis directions at an array period (L1 + L2) / L1 times the array period of the concave surface. As a result, even if the moving body 1105 is displaced not only in the Y-axis direction but also in the X-axis direction, the photodiode array 1102 and the photodiode array 1103 are used to perform displacement on the same principle as that described in the first embodiment. Can be detected.

  Further, the moving direction vector of the moving body 1105 in the XY plane can be obtained from the ratio of the displacement amounts in the X-axis and Y-axis directions. Similarly, the speed in the X-axis direction can be detected in addition to the Y-axis direction based on the same principle as the method described in the fourth embodiment. Furthermore, the velocity direction vector in the XY plane can be detected from the detected velocity ratio in the X axis direction and the Y axis direction.

(Modification)
As described above, the embodiment has been described in which the curvature is different between the central portion and the peripheral portion with respect to the curved surface portion of the moving body. However, the present invention is not limited to this, and any first region and second region that differ as a whole in the curved surface portion The curvature may be made different by partially overlapping regions).

Moreover, although embodiment which measures a movement amount and a movement speed as movement information measurement was described, the measurement apparatus which measures a movement acceleration as movement information may be used. The movement acceleration can be calculated based on, for example, the amount of displacement of the moving speed of the moving body during a predetermined time. As described above, the movement information of the moving body measured in the present invention includes at least one of the movement amount, the movement speed, and the movement acceleration. Further, only the relative value of the position is related to the movement amount. It also includes the case where the absolute value of the position is detected. Needless to say, the technical matters described in the embodiments may be used in appropriate combination within the scope of the present invention.

101 .. Light source, 102 .. Moving object, 103 .. Concave surface, 104, 105 .. Photodiode array, 106 .. Optical pattern image, 201... Central part, 202 .. Outer edge part, 203.

Claims (11)

A light source;
A moving body that is irradiated with the light source and has a curved surface in a moving direction;
A light receiving element that receives the reflected or transmitted light collected from the curved surface;
In a mobile information measuring device having
The movement information measuring device, wherein the curved surface has a plurality of kinds of curvatures in the movement direction. The center wavelength of the light source is λ, the radius of curvature of the center of the curved surface is R1, the radius of curvature of the outer edge is R2, and the distance from the surface of the moving body of the light receiving element is between R1 and R2. The movement information measuring device according to claim 1, wherein, when arranged, the length C of the moving direction cross section of the moving body satisfies the following conditional expression.
C ≦ (R1 + R2) × √ (λ / | R1-R2 |) The following conditional expression is satisfied, where ΔZ is a variation amount of a distance between the surface of the moving body and the surface of the detector on which the light source and the light receiving element are mounted. The movement information measuring device described in 1.
| R1-R2 | ≧ ΔZ   The movement information measuring device according to claim 1, wherein the curved surface is a curved surface that reflects irradiation light from the light source.   The movement information measuring apparatus according to claim 1, wherein the curved surface is a curved surface that transmits irradiation light from the light source.   6. The movement information measuring device according to claim 1, wherein a plurality of the curved surfaces are provided periodically in the movement direction.   The movement information measuring device according to any one of claims 1 to 6, wherein the curvature of the curved surface continuously changes from a central portion of the curved surface to an outer edge portion of the curved surface. The light receiving element has a plurality of light receiving regions, and when the distance between the centers of adjacent light receiving regions is Pd with respect to the moving direction of the moving body,
The movement information measuring device according to claim 1, wherein the curved surface is arranged on a surface of the moving body so as to satisfy the following condition.
Pl = [L1 / (L1 + L2)] × Pd × k
Here, Pl is the arrangement period of the curved surfaces, and k is a positive integer.   9. The movement information measuring device according to claim 1, wherein the light receiving element is provided in a direction orthogonal to the moving body in addition to the moving direction of the moving body. 10.   2. The relative speed between the moving body and the light receiving element is detected from a displacement amount of the moving body in a predetermined time or a passing time of the moving body that passes a predetermined distance interval. 10. The movement information measuring device according to any one of items 9 to 9.   The movement information measuring device according to claim 1, wherein at least one of a movement amount, a movement speed, a movement acceleration, and an absolute value of the position of the moving body is measured as movement information.