JP5133614B2 - 3D shape measurement system - Google Patents

Description

The present invention relates to a three-dimensional shape measurement system, more particularly relates to the optimum three-dimensional shape measurement system, particularly for measuring the outer shape of the tire is rolling.

  A moire method is known as a method for measuring the three-dimensional shape of a stationary object. On the other hand, when measuring the three-dimensional shape of a moving object, for example, a rotating tire, this moire method cannot be used.

  As a countermeasure, in Patent Document 1, a grid-shaped optical mark is projected on the tire surface, and the tire is rotated to form a rolling tire. It is disclosed to shoot with. In this way, the method of photographing with three-dimensional coordinates has an advantage that the photographing apparatus can be easily set in a short time.

  However, in Patent Document 1, it is necessary to photograph the projected light mark simultaneously with at least two photographing devices. For this reason, when the light mark is projected on the blind spot of one or both of the photographing devices due to unevenness on the tire surface, measurement is impossible, and there is a possibility that a part that cannot be measured is partially generated. This also applies to general measurement objects other than tires.

In Non-Patent Document 1 , light (increasing modulated light) whose light intensity increases with time change is projected onto a subject, and the reflected light is photographed with a photographing device. Further, the light intensity increases with time change. By projecting diminishing light (decreasing modulated light) onto the subject and photographing the reflected light with the same photographing device, and calculating the distance from the photographing device to the subject by calculating the difference between the reflected light of the two, Determining a dimensional shape is disclosed. In this method, since it is not necessary to use a plurality of photographing apparatuses, it is difficult to cause the blind spots as described above. However, this method cannot accurately measure when the subject is moving or when light (for example, light from indoor lighting) is projected on the subject from elsewhere.
JP 2007-085836 A Latest optical 3D measurement (published by Asakura Shoten)

The present invention aims to provide in view of the aforementioned, the three-dimensional shape measurement system capable of measuring the three-dimensional shape of the measurement object the measuring object with high accuracy by moving at high speed To do.

The invention according to claim 1 is emitted from the light source that irradiates the measurement position of the measurement object with light while periodically changing the amount of light toward the measurement object with a predetermined fluctuation period. First, second, third, and fourth light receiving portions that receive reflected light reflected at the measurement position of the measurement object, and the reflected light from the first light receiving portion to the fourth light receiving portion. Each of the first to fourth light receiving units receives the reflected light distributed by the plurality of beam splitters and the plurality of beam splitters provided so as to be distributed to each of the plurality of beam splitters. The first light receiving unit receives light at a phase angle of 0 to π, the second light receiving unit receives light at a phase angle of π to 2π, and the third light receiving unit is − Light is received at a phase angle of π / 2 to π / 2, and the fourth light receiving portion is π / And control means for controlling the light receiving period so as to receive at ~3π / 2 phase angle, based from the first to the fourth amount of light received by each light receiving portion of the measurement object by using the phase shift method wherein by calculating the distance to the measurement position, the arithmetic processing means asking you to 3-dimensional coordinates of each of the measurement positions for the measurement object, for each of the measurement positions obtained by the pre Ki演 calculation processing means -out based on the three-dimensional coordinates, including a display means for displaying the three-dimensional shape of the measurement object.
Further, the invention according to claim 2 is directed to a light source that irradiates the measurement position of the measurement object with light while periodically changing the amount of light toward the measurement object with a predetermined fluctuation period.
First, second, and third light receiving portions that receive reflected light emitted from the light source and reflected at the measurement position of the measurement object, and the reflected light from the first light receiving portion to the third light receiving portion. A cube-type cross prism that is provided so as to be distributed evenly to each light-receiving unit, and the reflected light distributed by the cube-type cross-prism is received by each of the first to third light-receiving units. When receiving light, the first light receiving unit receives light with a phase angle of 0 to π, the second light receiving unit receives light with a phase angle of π / 2 to 3π / 2 with respect to the fluctuation period, and Based on the control means for controlling the light receiving period so that the third light receiving portion receives light at a phase angle of π to 2π, and the light amount received by each of the first to third light receiving portions, a phase shift method is performed. To calculate the distance of the measurement object to the measurement position. The calculation processing means for obtaining the three-dimensional coordinates for each measurement position for the measurement object, and the three-dimensional coordinates of the measurement object based on the three-dimensional coordinates for each measurement position obtained by the calculation processing means. Display means for displaying a dimensional shape.

In the present invention, it receives the reflected light was reflected by the object is emitted from the light source at the light receiving portion. Further, since the amount of light emitted from the light source varies periodically, the reflected light received by the light receiving unit also varies periodically.

Control means, by the light receiving unit, phase contrast light intensity periodic variation of the light source to receive the reflected light by the light receiving period for each half cycle. Then, the arithmetic processing means calculates the phase lag at the measurement position of the measurement object from the received light amount of each light receiving period, further, it calculates the distance to the stereotactic location measuring light receiving unit based on the phase lag.
Thus by the three-dimensional coordinates obtained based on the distance obtained for each measurement position Ru seek shape of the measuring object.

Here, in the first aspect of the invention, the first to fourth light receiving units and the plurality of beam splitters that distribute the reflected light to the respective light receiving units so that the amount of light is uniform are used, and 0 to π, π to Reflected light is received in a light receiving period of 2π, −π / 2 to π / 2, and π / 2 to 3π / 2. In the second aspect of the present invention, a cube-type cross prism that distributes the reflected light to the first to third light receiving portions and each light receiving portion so that the amount of light is uniform is used, and 0 to π and π / 2. The reflected light is received in the light receiving period of ˜3π / 2 and π˜2π. Therefore, it is possible to measure the three-dimensional shape of the measurement object by photographing for a very short time (for example, several tens of nanoseconds).

Further, it is possible to also be configured to not install the imaging device for several cars double. Therefore, it is not necessary to deal with images captured by a plurality of image capturing apparatuses, so that data processing is simple, and thus high-resolution 3D moving images can be output immediately.

Further, by receiving a single reflected light as described above, the blind spot of the photographing apparatus due to the unevenness of the surface of the measurement object is hardly generated. Therefore, since the measurement object parts that cannot be measured are greatly reduced, measurement can be performed with high accuracy.

The arithmetic processing means so computes the phase delay by the phase shift method, it is easy to calculate the phase delay.

According to a third aspect of the present invention , a microchannel plate is provided in each of the light receiving portions, and the control means controls the reflected light passing through the microchannel plate , whereby the light receiving period for each of the light receiving portions. To control .
Thus, the phase region (light receiving period) of the waveform received by each light receiving unit can be set by opening and closing the microchannel plate, and it is not necessary to provide a light opening and closing mechanism in the light receiving unit itself.

Note that an optical filter that attenuates light (external light) other than light from the light source may be provided in the light receiving unit. In this case, a non-attenuating wavelength region is usually set in the optical filter in accordance with the wavelength of light from the light source.
Further, the light source is in a ring shape, a light source and the light receiver may be a coaxial arrangement. This makes it possible to make the optical path lengths substantially the same between the emitted light and the reflected light.
Moreover, it is good also as a structure which arrange | positions a retroreflection object (glass bead etc.) in a measuring object, and increases the reflected light from a light source.

Furthermore, in view of improving the measurement accuracy by reducing the variations Doshu life of the light amount, it is preferred that only makes the light source and the light receiver are arranged close to each other.

Thus, it is possible to measure with a single imaging device having a plurality of light receiving portions, but it may also not be measured by installing the imaging device over a plurality. Therefore, it is not necessary to deal with images captured by a plurality of image capturing apparatuses, so that data processing is simple, and thus high-resolution 3D moving images can be output immediately.

Furthermore, the Rukoto using one imaging device as described above, the blind spot of the imaging device due to the unevenness or the like of the measurement object surface is less likely to occur significantly. Therefore, since the measurement object parts that cannot be measured are greatly reduced, measurement can be performed with high accuracy.

  Furthermore, by measuring with one imaging device in this way, the blind spot of the imaging device due to the unevenness of the tire surface or the like is significantly less likely to occur. Therefore, since the measurement object parts that cannot be measured are greatly reduced, measurement can be performed with high accuracy.

In the present invention, it is more preferable that when the reflected light from the measurement object is received by the light receiving unit, the light is received in the same phase over two cycles or more.
Thereby, an effect equivalent to amplifying the received waveform (light quantity) can be obtained. This is particularly effective when the light intensity (light quantity) of the reflected light is small.

According to the present invention, even when the measurement object is moved at a high speed Ru can measure the three-dimensional shape of the measuring object with high accuracy.

  Hereinafter, embodiments will be described and embodiments of the present invention will be described. In the second and subsequent embodiments, the same components as those already described are denoted by the same reference numerals, and description thereof is omitted.

[First Embodiment]
First, the first embodiment will be described. As shown in FIG. 1, the three-dimensional shape measurement system 10 according to this embodiment includes a light source 14 that emits light toward a rolling pneumatic tire 12 to be measured, and reflected light from the pneumatic tire 12. An imaging device (CCD camera) 16 that receives light, an arithmetic processing unit 18 that calculates the three-dimensional coordinates of the pneumatic tire 12 by calculating the image data captured by the imaging device 16, and enters the air based on the three-dimensional coordinates And an image display unit 20 for displaying a three-dimensional image of the tire 12. In the present embodiment, the optical path length until the light emitted from the light source 14 reaches the pneumatic tire 12 and the optical path length until the reflected light reflected by the pneumatic tire 12 reaches the imaging device 16 are: The distance d from the imaging device 16 to the pneumatic tire 12 is the same.

  The light source 14 is configured to emit light while changing the light amount in a short cycle. FIG. 3 shows a waveform 25 of the emitted light 24 (see FIG. 1) from the light source 14 and a waveform 29 of the reflected light 28 (see FIG. 1) reflected on the tire surface and taken into the imaging device 16. Due to the optical path length from the light source 14 to the imaging device 16, a time lag (Δt in FIG. 3) is generated between the waveform 25 and the waveform 29.

  Further, the photographing device 16 distributes the reflected light 28 reflected by the pneumatic tire 12 and transmitted through the optical filter and the photographing lens of the photographing device 16 to four light beams with equal light intensity as shown in FIG. Have beam splitters 30, 32, 34. Furthermore, the imaging device 16 includes four light receiving units 38A to 38D that receive reflected light (distributed light) emitted from the beam splitters 30, 32, and 34, respectively. The distances from the light receiving portions 38A to 38D to the pneumatic tire 12 are all the same. The light receiving portions 38A to 38D are, for example, CCD image sensors having 1024 × 768 pixels. In addition, the imaging device 16 includes MCPs (microchannel plates) 40A to 40D arranged on the incident sides of the four light receiving units 38A to 38D.

  The arithmetic processing unit 18 calculates the distance from the light receiving unit 38 for each measurement target position on the tire surface as follows, and obtains the three-dimensional coordinates of the tire surface.

As described above, the beam splitters 30, 32, and 34 distribute the reflected light 28 incident on the imaging device 16 into the four reflected lights 28A to 28D. MCP40A, as shown in FIG. 4 (A), opening the shutter only during a period from time _{T 0} so that the phase angle θ passes the reflected light 28A of 0~180 ° (0~Π radians) to _{T 2.} As a result, the partial waveform 29A is photographed by the light receiving unit 38A. MCP40B, as shown in FIG. 4 (B), opening the shutter only during a period from time _{T 2,} so that the phase angle θ passes the reflected light 28B of 180~360 ° (Π~2Π radians) to _{T 4.} As a result, the partial waveform 29B is photographed by the light receiving unit 38B. MCP40C, as shown in FIG. 4 (C), from time _{T -1} such that the phase angle θ passes reflected light 28C of -90~90 ° (-Π / 2~Π / 2 radians) to _{T 1} Open the shutter only during. As a result, the partial waveform 29C is photographed by the light receiving unit 38C. MCP40D, as shown in FIG. 4 (D), only from time _{T 1} so that the phase angle θ passes reflected light 28D of 90~270 ° (Π / 2~3Π / 2 radians) to _{T 3} Open the shutter. As a result, the partial waveform 29D is photographed by the light receiving unit 38D.

Hereinafter, the total received light amount of the reflected light 28A by the light receiving unit 38A is I ₀ , the total received light amount of the reflected light 28B by the light receiving unit 38B is I ₂ , the total received light amount of the reflected light 28C by the light receiving unit 38C is I ₋₁ , and the light receiving unit. continuing with the _{I 1} the total amount of received reflected light 28D by 38D.

  In the present embodiment, the light intensity (light quantity) of the emitted light 24 is set to a period in which a cosine wave is drawn as shown in FIG. Here, in this specification, the cosine wave refers to a waveform represented by the following expression.

ここで、Ｉは受光した反射光の光量（出力強度）、ｆは周波数、ｔは経過時間、θは位相角、ｂは主として外光などの他の光の光量、をそれぞれ示す。なお、空気入りタイヤ１２の反射率はａで反映されている。この式から判るように、位相を９０°（Π／２ラジアン）ずらすようにｂの値を設定すると上式は正弦波を示す式となる。従って、本明細書で余弦波とは正弦波をも含む定義となる。

Here, I represents the light amount (output intensity) of the received reflected light, f represents the frequency, t represents the elapsed time, θ represents the phase angle, and b represents the light amount of other light such as external light. The reflectance of the pneumatic tire 12 is reflected by a. As can be seen from this equation, when the value of b is set so that the phase is shifted by 90 ° (Π / 2 radians), the above equation becomes an equation representing a sine wave. Therefore, in this specification, the cosine wave is defined to include a sine wave.

Then, by using the phase shift method, the phase lag Tanθ at each measurement target position is calculated by the following equation by measuring I at four points while shifting the phase, that is, by obtaining I _{−1 to} I _2. Is done.

上式から判るように、このように位相シフト法で位相解析をすることによって、位相遅れＴａｎθをＩ_−１ 〜Ｉ_２ のみによって求めることができ、ａやｂの影響を、すなわち反射率や外光の影響を受けない値として算出することができる。

As can be seen from the above equation, by performing the phase analysis by the phase shift method in this way, the phase delay Tanθ can be obtained only by I _{−1 to} I ₂ , and the influence of a and b, that is, reflectance and external It can be calculated as a value that is not affected by light.

  In the present embodiment, the distance d between the photographing device 16 and the pneumatic tire 12 is set to a half wavelength of the waveform 25 (that is, a half wavelength of the waveform 29).

If the light emission amount by the light source (LED) 14 is P, a fluctuation component of time delay due to the distance d is added to the light reception amount l (x, y) for each photographing pixel of the light receiving units 38A to 38D, and p, l (X, y) is obtained by the following equation. Note that x means the horizontal coordinate of the photographed image, and y means the vertical coordinate of the photographed image.

Here, p, L ₀ (x, y), and L ₁ (x, y) are a light emission amount, a background (a light amount other than the light source 14), and a fluctuation amount, respectively.

Further, T _m (m = −1 to 4) is obtained by the following equation.

ここで、Δｔは上述したように波形２５と波形２９との間に生じたタイムラグを示す。

Here, Δt represents a time lag generated between the waveform 25 and the waveform 29 as described above.

I _{−1 to} I ₂ are calculated by the following equations.

“I ₀ -I ₂ ” and “I ₋₁ -I ₁ ” used in Equation ₂ are calculated as follows. By calculating the difference in this way, the influence of background light from the background is offset.

Therefore, (I ₀ −I ₂ ) / (I ₋₁ −I ₁ ) is calculated as follows.

Therefore, Δt, which is a time lag, can be obtained as follows.

  The distance d can be obtained based on this Δt (s) and the speed of light c (m / s). When the distance d is equal to or less than the half wavelength of the waveform 29, the distance d is obtained by calculating (C / 2) × Δt. Then, by obtaining the distance d for each measurement target position, the three-dimensional coordinates of each measurement target position can be obtained, and based on this, a three-dimensional image of the pneumatic tire 12 can be displayed on the image display unit 20. it can.

  As described above, in the present embodiment, the exposure time of the light receiving unit 38 can be completed in one cycle of the waveform 29 (for example, tens of millionths of a second). Therefore, even if the pneumatic tire 12 rolls at high speed, the three-dimensional shape can be obtained with high accuracy. Further, since the measurement is performed with the reflection time, the influence of the pattern to be measured is reduced. Even when the light amount fluctuation is small, it is possible to obtain a three-dimensional shape with high accuracy by increasing the total amount of received light by repeatedly receiving light in two cycles and three cycles.

  Furthermore, in this embodiment, there is only one photographing device 16 to be installed, and there is no need to install over a plurality of devices. Therefore, since the blind spots of the imaging device due to the unevenness of the tire surface are much less likely to occur, the area where measurement is impossible is greatly reduced, and moreover, it is necessary to deal with images taken with multiple imaging devices Since there is no data processing, data processing is simple.

In addition, the brightness | luminance (light emission amount) of the reflected light 28 is calculated | required by the sum total of I < _-1 > -I < ₂ > as shown by the following formula | equation.

The reflectance R is obtained by the following formula.

なお、数１６、数１７は、それぞれ、数１４、数１５と同じ式で示される。 L ₀ (x, y) and L ₁ (x, y) are obtained by the following equations.

Expressions 16 and 17 are represented by the same expressions as Expressions 14 and 15, respectively.

Using R, L ₀ (x, y), L ₁ (x, y), etc., it is possible to confirm the reliability of the calculated value such as the distance d.

[Second Embodiment]
Next, a second embodiment will be described. As illustrated in FIG. 5, the three-dimensional shape measurement system 50 according to the present embodiment includes a light source 54 that emits light toward the pneumatic tire 12 to be measured, and an imaging device that receives reflected light from the pneumatic tire 12 ( CCD camera) 56, an arithmetic processing unit 58 for calculating the three-dimensional coordinates of the pneumatic tire 12 by calculating the image data taken by the photographing device 56, and the three-dimensional of the pneumatic tire 12 based on the three-dimensional coordinates And an image display unit 20 for displaying an image.

  As the light source 54, a ring type LED arranged coaxially on the outer periphery of the photographing lens of the photographing device 56 is provided. FIG. 7 shows a waveform 65 of the emitted light 64 from the light source 54 and a waveform 69 of the reflected light 68 reflected on the tire surface and taken into the photographing device 56. The waveform 65 and the waveform 69 have the same shape as that shown in FIG. 3, and a time lag (Δt in FIG. 7) is generated between the waveform 65 and the waveform 69 due to the optical path length from the light source 54 to the imaging device 56. .

  The imaging device 56 is different in configuration and operation from the imaging device 16 used in the first embodiment. The imaging device 56 includes a beam splitter 70 that distributes the reflected light 68 reflected by the pneumatic tire 12 and transmitted through the optical filter and the imaging lens of the imaging device 56 into three as shown in FIG. For example, a cube-type cross prism is used as the beam splitter 70.

  Furthermore, the imaging device 56 includes three light receiving units 78A to 78C that receive reflected light (distributed light) emitted from the beam splitter 70, respectively. The distances from the light receiving portions 78A to 78C to the pneumatic tire 12 are all the same. The light receiving unit 78 has the same function as the light receiving unit 38. In addition, the imaging device 56 includes MCPs (microchannel plates) 80A to 80C arranged on the incident sides of the three light receiving units 78A to 78C. The MCP 80 has a function equivalent to that of the MCP 40.

  The arithmetic processing unit 58 calculates the distance from the light receiving unit 78 for each measurement target position on the tire surface as follows, and obtains the three-dimensional coordinates of the tire surface.

  The beam splitter 70 distributes the reflected light 68 incident on the imaging device 56 into three reflected lights 68. The MCP 80A opens and closes the shutter so that the reflected light 68A (FIG. 8A) having a phase angle θ of 0 to 180 ° (0 to radians) passes. As a result, the partial waveform 69A is photographed by the light receiving unit 78A. The MCP 80B opens and closes the shutter so that the reflected light 68B (FIG. 8B) having a phase angle θ of 90 to 270 ° (Π / 2 to 3Π / 2 radians) passes. The MCP 80C opens and closes the shutter so that the reflected light 68C (FIG. 8C) having a phase angle θ of 180 to 360 ° (Π to 2Π radians) passes through. The partial waveform 69C is photographed, and therefore, in each measured reflected light, both end portions of each phase angle range overlap each other.

The phase delay Tanθ at each measurement target position is calculated by the following equation.

The principle from which this equation is derived will be described below.
Assuming that the light receiving unit 78 is composed of four light receiving units, 0 to 180 ° (0 to Π radians), 180 to 360 ° (Π to 2 Π radians), and −90 to 90 ° (−Π / 2). It is assumed that reflected light is received by each of the four light receiving portions in four phase angle ranges of ˜Π / 2 radians) and 90 to 270 ° (Π / 2 to 3Π / 2 radians). The time during which the MCP opens the shutter is from time T _{0 to} T ₂ at _{0 to} 180 °, from time T _{2 to} T ₄ at 180 to 360 °, and from time T _{−1 at} −90 to 90 °. It is assumed that it is between time T _{1 and} T ₃ at 90 to 270 ° between ˜T ₁ . In this case, the received light amounts of the four light receiving units can be I ₀ , I ₁ , I ₋₁ , and I ₁ . Here, I ₀ , I ₁ , I ₋₁ , and I ₁ are represented by the following equations.

なお、数１９〜数２２は、それぞれ、数６〜数９と同じ式で示される。

Equations 19 to 22 are represented by the same equations as Equations 6 to 9, respectively.

なお、数２３、数２４は、それぞれ、数１０、数１１と同じ式で示される。 “I ₀ -I ₂ ” and “I ₋₁ -I ₁ ” are calculated as follows. By calculating the difference in this way, the influence of background light from the background is offset.

Note that Equations 23 and 24 are represented by the same equations as Equations 10 and 11, respectively.

“I ₀ + I ₂ ” and “I ₋₁ + I ₁ ” are calculated as follows. The background is extracted by calculating the sum in this way.

If I- ₁ is eliminated from these equations and the cosine component is obtained, the following equation is obtained.

なお、数２８は数１２と同じ式で示される。 The phase angle θ is obtained by the following expression from the sine component and the cosine component of the amount of fluctuation of the light amount.

Equation 28 is expressed by the same equation as Equation 12.

なお、数２９は数１３と同じ式で示される。 Therefore, the time lag Δt (x, y) is obtained by the following equation.

Equation 29 is expressed by the same equation as Equation 13.

  As described in the first embodiment, the three-dimensional coordinates of each measurement target position can be obtained by obtaining the distance d based on the time lag Δt (x, y) for each measurement target position. A three-dimensional image of the pneumatic tire 12 can be displayed on the image display unit 20. Therefore, according to the present embodiment, even if the number of the light receiving portions 78 is set to three and the number of partial waveforms forming the waveform 69 is three instead of four, the three-dimensional shape of the pneumatic tire 12 that rolls at high speed is increased. It can be measured with accuracy.

  In the present embodiment, as the light source 54, a ring type LED arranged coaxially on the outer periphery of the photographing lens of the photographing device 56 is provided. Therefore, the outgoing light 64 and the reflected light 68 are almost identical in optical path length, and can be projected from the same direction as the optical axis of the photographing device 56.

If Δt (x, y) is handled as a complex number as in the following formula, it is convenient because one cycle can be handled continuously with one formula.

なお、数３２は数１５と同じ式で示される。 Further, the amount of fluctuation of the light quantity is obtained by the sum of squares as follows.

Equation 32 is expressed by the same equation as Equation 15.

なお、数３４は数１４と同じ式で示される。 The amount of background external light can be obtained by the following equation.

Note that Equation 34 is expressed by the same equation as Equation 14.

<Example of the second embodiment>
In the present embodiment, the light source 54 is an LED that can change the amount of light at a short cycle of 50 MHz. This is convenient for extracting the influence at the round trip distance (2 × d) due to reflection. In this embodiment, the distance d is set to 3.0 m. As a result, Δt is 20 ns when the speed of light c is 3.0 × 10 ⁵ km / s. Table 1 shows the relationship between the distance d and the frequency f when the frequency f of the emitted light 64 from the light source 54 is changed as a parameter. In this embodiment, the frequency f is set so that the wavelength of the outgoing light 64 is 2d.

  An LED that emits near infrared light is used as the LED. As a result, the sensitivity of the photodiode constituting the photographic pixel can be increased, and in addition, adverse effects such as fluorescent lamps can be reduced by combination with a near-infrared transmission optical filter.

  The column of “three partial waveforms and three light receiving units” in FIG. 9 indicates that measurement is performed by shifting the phase angle so that both ends of the phase angle range overlap each other. The light receiving unit 78A has a time range 82A for measuring the partial waveform 69A, the light receiving unit 78B has a time range 82B for measuring the partial waveform 69B, and the light receiving unit 78C has a time range 82C for measuring the partial waveform 69C. Open and expose.

  In the second cycle, the partial waveforms may be measured by exposing the light receiving units 78A to 78C in the time ranges 82A to C in the same manner. Thereby, measurement accuracy can be improved. This is particularly effective when the change in the amount of reflected light 68 is small.

  Further, as shown in the column of “three partial waveforms and one light receiving unit” in FIG. 9, one light receiving unit 78 </ b> A reflects reflected light having a phase angle of 0 to 180 ° in the first cycle and phase in the second cycle. The reflected light having an angle of 90 to 270 ° may be measured, and the reflected light having a phase angle of 180 to 360 ° may be measured in the third period. Thereby, the installation number of a light-receiving part can be made into one.

[Third Embodiment]
Next, a third embodiment will be described. In the present embodiment, the three-dimensional shape measurement system 10 described in the first embodiment is used, and four waveforms in which both ends of the phase angle range overlap each other are measured by the light receiving units 38A to 38D.

  Thus, by measuring so that the both ends of a phase angle range may mutually overlap, a measurement precision improves more compared with 1st Embodiment.

<Example of the third embodiment>
In the column of “four partial waveforms and four light receiving units” in FIG. 9, the measurement is performed by shifting the phase angle so that both ends of the phase angle range overlap each other. Exposure is performed by opening the shutters of the MCPs 40A to D in the time range 92A in the light receiving unit 38A, in the time range 92B in the light receiving unit 38B, in the time range 92C in the light receiving unit 38C, and in the time range 92D in the light receiving unit 38D.

  As in the example of the second embodiment, the partial waveforms 92A to 92D may be measured by the light receiving units 38A to 38D in the same manner in the second period.

  Further, as shown in the column of “four partial waveforms and two light receiving parts” in FIG. 9, in the first and second periods, the light receiving part 78A is exposed in the time range 92A and the light receiving part 78B in the time range 92B. In the third and fourth cycles, the light receiving unit 78A may be exposed in the time range 92C and the light receiving unit 78B may be exposed in the time range 92D. Thereby, the number of installation of a light-receiving part can be halved to two.

In this case, the same principle, as shown in FIG. 10, by exposing the light receiving portion 38A while measuring I ₁ by exposing the light receiving portion 38B in the time range 102B at the end portion E of one waveform in a time range 102A I ₀ is measured, and the light receiving portion 38A is exposed in the time range 102C at the start portion F of the waveform continuous to this waveform to measure I ₂ and the light receiving portion 38B is exposed in the time range 102D to obtain I _{−. 1} may be measured, and the three-dimensional coordinates of the pneumatic tire 12 may be obtained based on these measurement results. Thus, the three-dimensional coordinates of the pneumatic tire 12 can be obtained by exposing the light receiving portions 38A and 38B in a very short time. For example, even if the period of the waveform 69 is T _L = 1/30 seconds, the time for exposing the end portion E and the start end portion F can be set to Δt _s = 1/10000 seconds. Further, as shown in FIG. 10, it may be exposed for more than once when determining the I ₀ ~I _2.

Further, as shown in the column of “four partial waveforms and one light receiving unit” in FIG. 9, only the light receiving unit 38A is used, and I ₀ is obtained by performing exposure in the time range 92A in the first cycle, and the second cycle. in search of I ₁ by exposing a time range 92B, obtains the I ₂ by the third periods eyes to be exposed in a time range 92C, the determination of the I _-1 by the four th cycle of exposing a time range 92D You may go. Thereby, the installation number of a light-receiving part can be made into one.

  The embodiments of the present invention have been described above with reference to the embodiments. However, these embodiments are merely examples, and various modifications can be made without departing from the scope of the invention. For example, in these embodiments, the emitted light emitted from the light source has been described as light having a cycle in which a sine wave or cosine wave is drawn. However, the present invention is not limited to this, and the cycle in which the triangular waveform 106 is drawn as shown in FIG. It may be light, or may be light having a period for drawing the pulse waveform 108 as shown in FIG.

  It goes without saying that the scope of rights of the present invention is not limited to these embodiments.

It is a mimetic diagram showing the three-dimensional shape measuring system concerning a 1st embodiment. It is a schematic diagram which shows dividing the reflected light from a tire with a beam splitter, and measuring with each light-receiving part with the imaging device of the three-dimensional shape measuring system which concerns on 1st Embodiment. In 1st Embodiment, it is a graph which shows that the phase difference has arisen with the emitted light from a light source, and the reflected light from a tire. FIGS. 4A to 4D are graphs each showing a partial waveform received by each light receiving unit in the first embodiment. It is a schematic diagram which shows the three-dimensional shape measuring system which concerns on 2nd Embodiment. It is a schematic diagram which shows dividing the reflected light from a tire with a beam splitter, and measuring with each light-receiving part with the imaging device of the three-dimensional shape measuring system which concerns on 2nd Embodiment. In 2nd Embodiment, it is a graph which shows that the phase difference has arisen with the emitted light from a light source, and the reflected light from a tire. FIGS. 8A to 8C are graphs showing partial waveforms received by the respective light receiving portions in the second embodiment. In the Example of 3rd Embodiment, it is explanatory drawing which shows the phase range of the partial waveform which a light-receiving part measures. It is a modification of the Example of 3rd Embodiment, and is explanatory drawing which shows the phase range of the partial waveform which a light-receiving part measures. In 1st Embodiment-3rd Embodiment, it is a graph which shows the modification of the waveform of the emitted light which a light source emits. In 1st Embodiment-3rd Embodiment, it is a graph which shows the modification of the waveform of the emitted light which a light source emits.

Explanation of symbols

10 Three-dimensional shape measurement system 14 Light source 16 Imaging device (light reception / arithmetic processing means)
18 Arithmetic processing device (light receiving / arithmetic processing means)
28A to D Reflected light 30 Beam splitter 32 Beam splitter 34 Beam splitter 38A to D Light receiving portions 40A to D MCP (microchannel plate)
50 Three-dimensional shape measurement system 54 Light source 56 Imaging device (light receiving / arithmetic processing means)
58 Arithmetic processing device (light receiving / arithmetic processing means)
68A-C Reflected light 70 Beam splitter 78A-C Light receiving part 80A-C MCP (microchannel plate)
d Distance Tanθ Phase lag

Claims (3)

A light source that irradiates the measurement position of the measurement object with light while periodically changing the amount of light toward the measurement object with a predetermined fluctuation period ;
First, second, third, and fourth light receiving portions that receive reflected light emitted from the light source and reflected at the measurement position of the measurement object ;
A plurality of beam splitters provided so as to distribute the reflected light from the first light receiving unit to each of the fourth light receiving units, and to distribute the light equally.
When the reflected light distributed by the plurality of beam splitters is received by each of the first to fourth light receiving units, the first light receiving unit has a phase angle of 0 to π with respect to the fluctuation period. The second light receiving unit receives light with a phase angle of π to 2π, the third light receiving unit receives light with a phase angle of −π / 2 to π / 2, and the fourth light receiving unit. Control means for controlling the light receiving period so that light is received at a phase angle of π / 2 to 3π / 2,
Based on the amount of light received by each of the first to fourth light receiving units, a distance to the measurement position of the measurement object is calculated using a phase shift method , whereby the measurement position of the measurement object is measured. and arithmetic processing means asking you to three-dimensional coordinates of each,
And display means before based-out on the 3-dimensional coordinates of each of the measurement positions obtained by Ki演 calculation processing means for displaying the three-dimensional shape of the measurement object,
A three-dimensional shape measuring system. A light source that irradiates the measurement position of the measurement object with light while periodically changing the amount of light toward the measurement object with a predetermined fluctuation period;
First, second, and third light receiving portions that receive reflected light emitted from the light source and reflected at the measurement position of the measurement object;
A cube-shaped cross prism that is provided so as to distribute the reflected light from the first light receiving unit to each of the third light receiving units in an equal amount of light;
When the reflected light distributed by the cube-type cross prism is received by each of the first to third light receiving units, the first light receiving unit has a phase angle of 0 to π with respect to the fluctuation period. For controlling the light receiving period so that the second light receiving unit receives light at a phase angle of π / 2 to 3π / 2 and the third light receiving unit receives light at a phase angle of π to 2π. Means,
Based on the amount of light received by each of the first to third light receiving units, a distance to the measurement position of the measurement object is calculated using a phase shift method , whereby the measurement position of the measurement object is measured. Arithmetic processing means for obtaining a three-dimensional coordinate for each;
Display means for displaying a three-dimensional shape of the measurement object based on the three-dimensional coordinates for each of the measurement positions determined by the arithmetic processing means;
A three-dimensional shape measuring system. 2. The light receiving period for each light receiving unit is controlled by providing a micro channel plate in each of the light receiving units, and the control unit controls the reflected light passing through the micro channel plate. 3. The three-dimensional shape measurement system according to 2.

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