JP2828797B2 - Measuring method for depth of minute concave surface - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recognizing a three-dimensional shape of an object in a non-contact manner, and more particularly to a method for measuring the depth of a minute concave surface for recognizing the shape of a liquid surface.

[0002]

2. Description of the Related Art There have been many proposals for recognizing the three-dimensional shape of an object in a non-contact manner, and some of them have been embodied and put to practical use. Among them, a spotlight type distance sensor that applies the so-called triangulation principle is the simplest sensor for measuring the distance to an object without contact. FIG. 18 shows a simple principle diagram of this distance sensor.

In this distance sensor, for example, light generated from a light source unit 1 using a semiconductor laser or the like is condensed into a spot light by a light projecting optical system 2 using a lens or the like, and an object 6 to be measured is collected.
The image 3 of the spot light formed on the surface is re-imaged on the light receiving element by the light receiving optical system 4. As the light receiving element to be re-imaged, a photoelectric conversion element 5 such as a PSD for converting the image forming position of the spot light into an electric signal is used.

According to this principle, when the distance L from the distance sensor to the measuring object 6 changes, the image forming position of the spot light formed on the light receiving element changes correspondingly. The distance from the distance sensor to the measurement object 6 is obtained from the change in the image formation position. Of the distance sensors to which such a principle of triangulation is applied, five photoelectric conversion elements P
The one using the SD is characterized by its high response speed, and has the advantage that the sensor section can be downsized and the signal processing is easy.

[0005]

However, when a PSD is used as the photoelectric conversion element 5, if light generated due to some cause, for example, secondary reflection, etc., enters the photoelectric conversion element 5 on the surface of the measuring object 6, Since it is impossible to distinguish between the spot light for measurement and the noise light, there is a problem that erroneous measurement is caused.

This problem will be considered in the case of measuring the depth of a minute concave liquid surface in order to detect the amount of application when a highly viscous liquid having a mirror surface is applied. First, FIG. 19 shows an example of a reflection model of projected light when the measurement target 6 is a flat surface, and an example of a reflected light amount to a light receiving optical system. As described above, when the measurement target 6 is a flat surface, noise light other than spot light does not exist unless another external light source is considered, so that the distance measurement to the measurement target is also accurately performed. In the figure, X is a light emitting axis, Y is a light receiving axis,
Z indicates the reflection pattern on the surface.

However, when considering a liquid surface that is a minute concave surface as described above, a problem specific to the object occurs. An optical model when considering the liquid surface is the small concave shown in FIGS. 20 (21 enlarged view). The surface of the liquid that is the measurement object 6 has a minute concave surface,
Further, the liquid surface has a reflection characteristic close to regular reflection.
In this case, in addition to the spot light Xa projected from the light projecting optical system, a component Xb not collected as a spot light among the lights emitted from the same light projecting optical system (hereinafter referred to as a stray light component).
Although it is small in strength, it exists over the entire area of the target concave surface 6a. However, depending on the angle that the target concave surface forms with the light projecting / receiving angle of the measurement sensor, the inclination of the surface of the target concave surface 6a may cause the light emitted from the light projecting optical system to be specularly reflected to the light receiving optical system. Yb indicates a light receiving component of a regular reflection component corresponding to the stray light component Xb.

When this is viewed from the light receiving optical system, the light receiving optical system has a diffuse reflection component Yc of the spot light Xa on the target surface.
And a component Yb in which the stray light component Xb is specularly reflected by the surface having an inclination for specular reflection with respect to the above-described light receiving optical system. Thus, the floodlight spot X
Noise light other than “a” is constantly generated due to the shape characteristic of the object, thereby preventing distance measurement to the surface of the measurement target 6.

To avoid this, Japanese Patent Laid-Open Publication No.
As shown in Japanese Patent No. 415, a true spot light and a noise light are separated from a plurality of spot light images which are re-imaged using, for example, a CCD element as the photoelectric conversion element 5 to compare the spot light image and the noise light. There is also a method of recognizing the spot light of the target and thereby obtaining an accurate distance to the object to be measured.

However, if such a method is used, it goes without saying that the advantage of using the PSD as described above is lost. The present invention has been made in view of such problems, Toko filtrate is an object of the present invention, when measuring the distance to the measurement object using the spot light type meter, generated by the shape feature Avoid noise light
It is an object of the present invention to provide a method for measuring the depth of a minute concave surface, which can accurately measure the distance to an object to be measured.

[0011]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides a liquid having a minute concave surface for detecting the amount of application when a highly viscous liquid having a mirror surface is applied. When measuring using a measuring instrument that measures the distance to the object to be measured using the principle of triangulation by irradiating a spot light on the concave part of the object with a measuring method that measures the depth of the surface, When a specular reflection surface having a certain angle determined by the angle between the light projecting axis and the light receiving axis exists at a position other than the measurement point of the target concave surface and within the field of view of the light receiving optical system, the light projecting axis of the measuring device and the light receiving axis While keeping the formed angle constant, the optical system of the measuring instrument gives a predetermined angle to the angle formed with the target concave surface, so that the regular reflection surface present in the target concave surface does not exist in the field of view of the light receiving optical system. Then, the depth of the target concave surface is measured.

The depth of the concave surface of the object is measured while changing the inclination of the measuring device so that the angle formed by the optical system of the measuring device and the concave surface of the object slightly changes, and the depth of the positive surface existing in the field of view of the light receiving optical system is measured. When an erroneous measurement due to the reflection surface occurs, the one indicating the deepest measured value among the plurality of measured values may be used as a true value. Further, a TV camera is arranged at a position corresponding to the light receiving optical system of the measuring instrument, an image of the spot light projected from the light projecting optical system is displayed on the monitor TV, and the angle of the optical system of the measuring instrument is gradually changed. While examining the positional relationship between the image of the spot light and the image of the specular reflection light, the angular distribution of the liquid surface of the target concave surface is clarified, and the angle of the optical system of the measuring instrument is set to the optimum angle with respect to the shape of the target concave surface. May be set.

Further, the measuring device is caused to scan in the diameter direction of the concave surface of the object, and the output value of the measuring device corresponding to the cross-sectional direction of the concave surface of the object is stored, and this scanning is performed by the optical system of the measuring device. The angle of the optical system of the measuring instrument is adjusted to the optimal angle with respect to the shape of the target concave surface by comparing the obtained output value changes in the cross-sectional direction of the plurality of target concave surfaces with a slight change in the angle formed. May be set.

[0014]

As described above, the cause of the noise light is due to the angle between the optical system of the measuring instrument and the concave surface of the object. However, the present invention sets the angle θ between the light projecting axis X and the light receiving axis Y of the measuring instrument. By tilting the entire optical system of the measuring device by a certain angle θa in a fixed direction while maintaining the constant as shown in FIG. 1, the reflection pattern Z is tilted and the above-described measurement is performed in the concave surface 6 a of the measuring object 6. There is no longer any surface having a regular reflection slope with respect to the light receiving optical system of the measuring instrument. As a result, only the image of the measurement spot light enters the light receiving element of the measuring instrument, and the measurement object 6
It is possible to accurately measure the distance to the surface.

[0015]

The present invention will be described below with reference to examples. (Embodiment 1) The measuring device used in the embodiment uses the distance sensor shown in FIG. 18 and is not particularly shown.

FIGS. 2A and 2B are model diagrams when the optical system of the distance sensor is not tilted. Assuming that the angle between the light projecting axis X and the light receiving axis Y of the sensor is θ, the inclination of the concave surface 6a that makes regular reflection with respect to the light receiving optical system of the distance sensor is 1 / 2θ. In this case, the spot light Xa
Let d be the distance to the place where noise light is generated by specular reflection light.
Indicated by

Next, FIGS. 3A and 3B are model diagrams in the case where the angle between the light projecting axis X and the light receiving axis Y of the distance sensor is increased by α in order to avoid the regular reflection surface. . By doing so, the inclination of the surface of the distance sensor that makes regular reflection with respect to the light receiving optical system becomes （(θ + α), and the distance d between the spot light Xa and the place where noise light is generated due to the regular reflection light is set. It can be larger than in the case of FIG. FIGS. 4A and 4B are model diagrams when the optical system of the distance sensor is similarly tilted by ψ in order to avoid the regular reflection surface.

By doing so, the inclination of the surface that regularly reflects the light receiving optical system of the distance sensor is 1 / 2θ + θ.
And the distance d between the spot light Xa and the place where the noise light is generated due to the specular reflection light is smaller than the two examples described above.
It is possible to increase the size more effectively, and in some cases, it becomes possible not to have a regular reflection surface having the angle in the target concave surface 6a.

FIGS. 5A, 5B, 6A, 6B, 7A, 7B, 8A, and 8B show the case where the optical system of the distance sensor is not tilted. The difference in the case of tilting is shown when the depth of the target concave surface 6a changes. When the optical system of the distance sensor shown in FIGS. 5A and 6A is not tilted, the position of the spot light Xa for measurement is located within the field of view of the light receiving optical system as shown in FIG. Thus, an image at the position of the regular reflection light spot light Xb is obtained.

On the other hand, when the optical system of the distance sensor is tilted by ψ with respect to the same concave surface 6a as shown in FIGS. 7A and 8A, the image in the field of view of the light receiving optical system becomes FIG.
(B), as shown in FIG. 8 (b), the positional relationship between the spot light Xa for measurement in the field of view of the light receiving optical system and the spot light Xb of the regular reflection light which is noise light changes, and the measured value is thereby changed. Is also changing.

The minute concave 6a is a constant subject measured in this way
By properly setting the angle formed by the optical system of the distance sensor that is the measuring device, it is possible to accurately measure the distance to the measurement object while avoiding the influence of the specularly reflected light spot light Xb that is noise light. It becomes possible. Second Embodiment As described in the first embodiment, if the angle of the optical system of the distance sensor is adjusted in accordance with the shape of the target concave surface 6a, accurate measurement can be performed without being affected by the specular reflected light spot light that is noise light. Measurement is possible.

In this embodiment, the distance to the target concave surface 6a is repeatedly measured while gradually changing the inclination of the distance sensor, and the change in the measured value is examined.
First, when an erroneous measurement occurs due to the influence of noise light due to the specular reflection surface of the target concave surface 6a, the measured value must be a value that is shallower than the true value, that is, a value where the distance between the distance sensor and the target concave surface 6a is shorter. Is clear.

Accordingly, in the present embodiment, when the measurement is repeated while changing the angle of the distance sensor as described above, the one with the lowest measured value of the distance sensor is adopted as the true value. Alternatively, the measured value at the time when the measured value of the distance sensor stops showing a change is adopted as a true value. By doing so, the distance to the object to be measured can be accurately measured by the spot light type distance sensor using the PSD while avoiding the influence of noise light.

FIG. 9 is a flow chart of a measurement procedure in the case where the one with the lowest measured value of the distance sensor is adopted as the true value. In this case, after setting the angle of the distance sensor to the initial value θ. The angle of the distance sensor is changed by Δθ, the distance to the target concave surface 6a is measured each time, and the measured value P (i) is read. When the change range is completed, the lowest value of the measured values P (i) is obtained. Is adopted as a true value.

FIG. 10 shows a flowchart of a measurement procedure when the minimum value of the measured value when the output value of the distance sensor stops showing a change is adopted as a true value. In this case, the measured value P ( Whether or not there is a change in i) is determined each time the measurement is made, and when no change is found, the measured value P (i) is adopted as a true value. That is, the measured value P at this time
This is because (i) is the lowest value.

FIG. 11 is a graph showing the relationship between the inclination of the distance sensor and the measured value P (i) when a specific minute concave surface 6a is measured. (Embodiment 3) In the present embodiment, a TV camera 7 is arranged at a position corresponding to a light receiving optical system of a distance sensor, and the state of specularly reflected spot light on a surface to be measured is displayed on a monitor TV screen via the TV camera 7. An optical system that can monitor the image is prepared.

Using this optical system, the optical system forms the target concave surface 6a while actually observing the state of the specularly reflected spot light on the target concave surface 6a due to the light emitted from the light source unit 1 of the distance sensor. FIG. 12A and FIG.
(A), as shown in FIG. 14 (a), angles ψ = 0, ψ ₁ ,
gradually varied so on [psi _2, and angle of the optical system, FIG trends appearance of a spot light Xa and noise light for measuring specular reflection spot Xb 12 (b), FIG. 13 (b), the 14 The angle distribution of the target concave surface 6a is obtained by previously confirming and clarifying on the screen of the monitor TV shown in (b), and the distance to the target concave surface 6a is measured by the spot light type distance sensor using the PSD. In this case, the angle of the optical system of the distance sensor can be set to an optimum angle in advance with respect to the shape of the target concave surface 6a. The distance can be measured accurately.

(Embodiment 4) In this embodiment, as shown in FIGS. 15 (a) to 17 (a), the distance sensor A scans in the diameter direction of the target concave surface 6a, and the output signal from the distance sensor A during that time. And a distance sensor A
15 (a) to 17 (a), the angle formed by the optical system with the object concave surface 6a is slightly changed to ψ = 0, ψ ₁ , 繰 り 返 す₂ as shown in FIGS. ~ FIG.
By comparing the output change in the cross section direction of the target concave surface 6a obtained as shown in (b), the angular distribution of the target concave surface 6a is obtained, and the distance to the target concave surface 6a is obtained by the spot light type distance sensor using the PSD. When measuring the object, it is possible to set the angle of the optical system of the distance sensor to an optimum angle in advance with respect to the shape of the target concave surface 6a, and to avoid noise light generated by the shape characteristic, Distance can be accurately measured. In the figure, d indicates the output value of the distance sensor, and x indicates the sensor displacement.

[0029]

According to the first aspect of the present invention, there is provided a measuring method for measuring the depth of a minute concave liquid surface in order to detect the amount of application when a highly viscous liquid having a mirror surface is applied. When measuring with a measuring instrument that measures the distance to the object to be measured using the principle of triangulation by irradiating a spot light on the concave part of the object, the angle between the light emitting axis and the light receiving axis of the measuring instrument When the specular reflection surface having a certain angle determined by is present in the field of view of the light receiving optical system other than the measurement point of the target concave surface,
While maintaining the angle between the light-emitting axis and the light-receiving axis of the measuring instrument constant, the optical system of the measuring instrument gives a predetermined angle to the angle formed by the concave surface of the object, and the specular reflection surface existing in the concave surface of the object forms the light receiving optical axis. Since the depth measurement of the concave surface of the object is performed so as not to be present in the field of view of the system, there is no surface having a regular reflection slope with respect to the light receiving optical system of the measuring instrument, and as a result, the surface is generated by the shape feature. Noise light can be avoided, and only the image of the measurement spot light enters the light receiving element of the measuring instrument, so that the distance to the target concave surface can be measured accurately.

According to a second aspect of the present invention, the depth of the concave surface of the object is measured while changing the inclination of the measuring device so that the angle formed by the optical system of the measuring device and the concave surface of the object is slightly different, and the light receiving optical system is provided. In the case where an erroneous measurement occurs due to a specular reflection surface present in the field of view of the system, a value indicating the deepest measurement value among the plurality of measurement values is used as a true value, and is the same as the invention according to claim 1. Has a significant effect.

According to a third aspect of the present invention, a TV camera is arranged at a position corresponding to a light receiving optical system of the measuring instrument, and an image of a spot light projected from the light projecting optical system is displayed on a monitor TV. The angle distribution of the liquid surface of the target concave surface is clarified by examining the positional relationship between the image of the spot light and the image of the specular reflection light while slightly changing the angle of the optical system of the measuring instrument, and the angle of the optical system of the measuring instrument Is set to an optimum angle with respect to the shape of the target concave surface, and the invention according to claim 4 scans the measuring device in the diameter direction of the target concave surface, and sets the measuring device corresponding to the cross-sectional direction of the target concave surface. The output value is stored, and this scanning is repeated by slightly changing the angle of the optical system of the measuring device with the target concave surface, and comparing the obtained output changes in the cross-sectional direction of the plurality of target concave surfaces. The angle of the optical system of the measuring instrument Since the is set to an optimal angle with respect to shape, these inventions also have invention the same effect as in claim 1, wherein.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

[2] The distance is an explanatory view when bought Do tilted optical system of the sensor.

FIG. 3 is an angle α between the light emitting axis and the light receiving axis of the distance sensor .
FIG. 7 is an explanatory diagram in a case where the number of light beams is increased.

FIG. 4 is an explanatory diagram when the optical system of the distance sensor according to the first embodiment of the present invention is tilted by ψ.

FIG. 5 is an explanatory diagram in a case where the depth of an object concave surface is shallow and the optical system of the distance sensor is not tilted.

FIG. 6 is an explanatory diagram in a case where the depth of an object concave surface is deep and the optical system of the distance sensor is not tilted.

FIG. 7 shows an optical system of the distance sensor in which the depth of the concave surface of the object is small.
FIG. 9 is an explanatory view of Embodiment 2 of the present invention, which is tilted only.

FIG. 8 shows an optical system of the distance sensor in which the depth of the concave surface of the object is deep.
FIG. 9 is an explanatory view of Embodiment 2 of the present invention, which is tilted only.

FIG. 9 is a flowchart illustrating a measurement procedure when the lowest value according to the second embodiment of the present invention is adopted as a true value.

FIG. 10 is a flowchart illustrating a measurement procedure when focusing on a change in a measurement value according to the second embodiment of the present invention.

FIG. 11 is a diagram illustrating the relationship between the inclination and the output value of the distance sensor according to the second embodiment of the present invention.

FIG. 12 is an explanatory diagram when the optical system of the distance sensor according to the third embodiment of the present invention is not tilted.

FIG. 13 illustrates an optical system of a distance sensor according to a third embodiment of the present invention.
It is an explanatory view when inclined by _1.

FIG. 14 illustrates an optical system of a distance sensor according to a third embodiment of the present invention.
FIG. 4 is an explanatory diagram in the case of tilting by _two .

FIG. 15 is an explanatory diagram when the optical system of the distance sensor according to the fourth embodiment of the present invention is not tilted.

FIG. 16 illustrates an optical system of a distance sensor according to a fourth embodiment of the present invention.
It is an explanatory view when inclined by _1.

FIG. 17 illustrates an optical system of a distance sensor according to a fourth embodiment of the present invention.
FIG. 4 is an explanatory diagram in the case of tilting by _two .

FIG. 18 is a diagram illustrating the principle of a spot light type distance sensor to which the principle of triangulation is applied.

FIG. 19 is an explanatory diagram showing a relationship between light emitted from a light projecting optical system of a distance sensor, light reflected on a flat surface of an object to be measured, and a light receiving optical system for receiving the light.

FIG. 20 is a diagram illustrating the relationship between light emitted from a light projecting optical system of a distance sensor, light reflected on a minute concave surface, and a light receiving optical system for receiving the light.

21 is an enlarged explanatory view of a main part of FIG. 20;

[Explanation of symbols]

 X Projecting axis Y Receiving axis Z Reflection pattern 6a Concave concave surface 6 Measurement object

Continuation of front page (56) References JP-A-2-105002 (JP, A) JP-A-4-181108 (JP, A) JP-A-60-36908 (JP, A) JP-A-62-115315 (JP) , A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G01B 11/00-11/30 G01C 3/00-3/32

Claims (4)

(57) [Claims] 1. A measuring method for measuring the depth of a minute concave liquid surface in order to detect the amount of application when a highly viscous liquid having a mirror surface is applied. When measuring using a measuring instrument that measures the distance to the object to be measured using the principle of triangulation by irradiating light, a positive angle having a fixed angle determined by the angle formed by the projecting axis and the receiving axis of the measuring instrument When the reflection surface is located at a point other than the measurement point of the concave surface of the object and is within the field of view of the light receiving optical system, the optical system of the measuring device is moved to the concave surface while keeping the angle between the light emitting axis and the light receiving axis of the measuring device constant. And a predetermined angle to the angle formed, so that the regular reflection surface present in the target concave surface does not exist in the field of view of the light receiving optical system, the depth of the target concave surface characterized by performing a depth measurement of the concave surface Depth measurement method. 2. The depth of an object concave surface is measured while changing the inclination of the measuring device so that an angle formed by the optical system of the measuring device with the concave surface of the object is slightly different, and the depth of the concave surface is within the field of view of the light receiving optical system. 2. The method according to claim 1, wherein, when an erroneous measurement by the specular reflection surface occurs, a value indicating the deepest measured value among the plurality of measured values is used as a true value. 3. A T position at a position corresponding to a light receiving optical system of the measuring device.
A V-camera is arranged, an image of the spot light projected from the light projecting optical system is displayed on the monitor TV, and the angle of the optical system of the measuring device is changed little by little to change the image of the spot light and the specular reflected light. 2. The method according to claim 1, wherein an angular distribution of the liquid surface of the target concave surface is clarified by examining a positional relationship between the images, and an angle of an optical system of the measuring instrument is set to an optimum angle with respect to a shape of the target concave surface. The method for measuring the depth of a minute concave surface described in the above. 4. The measuring device is scanned in the diameter direction of the concave surface of the object, and the output value of the measuring device corresponding to the cross-sectional direction of the concave surface of the object is stored, and the scanning is performed by the optical system of the measuring device. By repeatedly changing the angle formed with the concave surface and repeating the obtained output value change in the cross-sectional direction of the plurality of target concave surfaces, the angle of the optical system of the measuring instrument is optimized for the shape of the target concave surface. 2. The method according to claim 1, wherein the angle is set to an angle.