JP7031664B2 - Object detection device, object detection method, and program - Google Patents

Description

The present disclosure relates to an object detection device, an object detection method, and a program. Specifically, the present invention relates to an object detection device that executes processing such as detection processing of a transparent object and stress detection in an object, an object detection method, and a program.

As a process of detecting the presence or absence of an object, there is a process using a photoelectric sensor.
For example, in a setting where the object to be detected passes irregularly on the belt conveyor of the production line of the factory, the light is irradiated on the belt conveyor and the reflected light is received by the photoelectric sensor.

The output value of the photoelectric sensor is
(A) When there is nothing on the belt conveyor and the photoelectric sensor receives the reflected light from the dedicated reflector or the belt conveyor surface.
(B) When an object exists on the belt conveyor and the photoelectric sensor receives the reflected light of the object.
Will make a difference. Objects can be detected based on this difference.

However, when the object to be detected is a transparent object with high light transmittance, the amount of reflected light received by the photoelectric sensor is almost the same in both cases where the detection target exists and when it does not exist. And there is no big difference.
Therefore, there is a problem that the detection ability of the object is lowered.

As a configuration for improving the detection accuracy of a transparent object having a high light transmittance, there is a configuration using polarization. Taking advantage of the property that when linearly polarized light is transmitted through a transparent object, it is converted to elliptically polarized light, a linearly polarized light filter (polarizing plate) is placed in the light projecting section and the light receiving section to transmit the linearly polarized light through the transparent object. This is a method of receiving this transmitted light with a sensor, increasing the amount of attenuation of the received light amount, and improving the detection accuracy.

For example, in Patent Document 1 (Japanese Unexamined Patent Publication No. 10-11365), a light projecting unit and a light receiving unit are arranged so as to sandwich an object detection position, and a linear polarizing plate in one direction is arranged in each of the light emitting unit and the light receiving unit. The composition is disclosed.
When a transparent object does not exist at the object detection position, the linearly polarized light emitted from the light projecting unit is received by the light receiving unit in which the linear polarizing plate is arranged as it is. On the other hand, when a transparent object exists at the object detection position, the linearly polarized light emitted from the light projecting portion passes through the transparent object and is converted into elliptically polarized light, and this elliptically polarized light is converted into elliptically polarized light by the light receiving portion in which the linear polarizing plate is arranged. Received light.
With such a configuration, it is possible to greatly change the amount of light received by the light receiving unit depending on the presence or absence of a transparent object, and it is possible to detect a transparent object with high accuracy.

Further, in Patent Document 2 (Japanese Unexamined Patent Publication No. 7-294663), as in the above document, a light projecting portion and a light receiving portion are arranged so as to sandwich the object detection position, and the light projecting portion is a unidirectional linear polarizing plate. Discloses a configuration in which a polarizing plate in two directions is arranged in a light receiving portion.
With this configuration, even if the orientation of the surface of the object to be detected changes and the amount of polarized light received in one direction is not attenuated, the attenuation of the amount of light in the remaining one direction can be observed, and the transparent object can be made more stable than Patent Document 1. The configuration that enables detection is disclosed.

Further, Patent Document 3 (Japanese Unexamined Patent Publication No. 2010-107475) has a configuration in which a light projecting unit and a light receiving unit are installed so as to sandwich an object detection position, and the light receiving unit is set at three spatially separated positions. It is disclosed.
The light projecting unit has a linear polarizing plate in one direction, and the three light receiving units have a polarizing plate having different directions.
By analyzing changes in the amount of light received by the three light receiving units, it is possible to perform highly accurate detection even if the detection target is a transparent flat plate.

Further, for example, in a factory production line, in addition to the above-mentioned object detection, residual stress is often measured as a quality inspection of, for example, the strength of a molded product such as a resin.
If the residual stress is large, there is a high possibility that deformation, cracking, etc. will occur. For example, a resin molded product having a residual stress larger than the reference value is removed from the manufacturing process as a defective product.

As a conventional general method for measuring residual stress, a polarizing plate on the illumination side is rotated to a plurality of angles to irradiate an object, and the transmitted light is passed through a polarizing plate having a polarization angle corresponding to each polarization angle on the illumination side. There is a way to observe.
However, this method requires an accurate rotation control mechanism for the polarizing plate, control of the measurement timing on each light receiving side, and the like, and requires a high-cost and complicated system. In addition, there is a problem that real-time measurement is difficult because it takes time to analyze the observation data.

Japanese Unexamined Patent Publication No. 10-11365 Japanese Unexamined Patent Publication No. 7-294663 Japanese Unexamined Patent Publication No. 2010-107475

As described above, various proposals have been made for a configuration for detecting a transparent object by using a polarizing filter (polarizing plate).
When observing one linearly polarized light through polarizing plates in a plurality of directions, it changes in a sinusoidal manner depending on the polarization direction used for the observation. Basically, this change in sine function can be restored by observing in three different polarization directions.
That is, when observed in three directions, even if the object is transparent, a large amount of light attenuation always occurs in at least one of the directions, and stable detection becomes possible.

However, the methods described in Patent Document 1 and Patent Document 2 described above can observe only the amount of light in two polarization directions at the maximum. Therefore, depending on the shape and orientation of the object to be detected, there is a problem that the light amount attenuation required for detection does not occur and stable detection cannot be performed.
Specifically, for example, if the orientation of the transparent flat plate is changed, there is a high possibility that detection will not be possible.

Further, the configuration described in Patent Document 3 solves the above problem by observing different polarizations in three directions in three light receiving units.
However, since the configuration described in Patent Document 3 is a configuration in which the irradiation light from one light projecting unit is received by the light receiving units at three spatially separated positions, the light receiving from each of the three light receiving units is received. The light to be detected is not the transmitted light at the same point of the detection target, but the transmitted light at different positions.
Therefore, when the detection target is small, each of the three light receiving units may not be able to receive the transmitted light of the detection target at the same time, which causes a problem that the detection accuracy is lowered.

The present disclosure has been made in view of the above problems, for example, and is an object detection device and an object that enable highly accurate object detection processing when the object to be detected is an object having a high light transmission rate. The purpose is to provide a detection method as well as a program.

Further, in one embodiment of the present disclosure, an object detection device, an object detection method, and a program capable of detecting stress in an object at the same time as detecting an object are provided.

The first aspect of this disclosure is
A floodlight that outputs at least three types of polarization in different polarization directions, and
A light receiving unit that receives the output light of the light projecting unit at at least three different observation polarization angles.
It has a data processing unit that determines whether or not a transparent object exists in the optical path from the light emitting unit to the light receiving unit based on the light receiving signal of the light receiving unit.
The data processing unit
An object detection device having a stress calculation unit that calculates the residual stress of the transparent object by using the light receiving signals of a plurality of different observation polarization angles received by the light receiving unit when it is determined that a transparent object exists in the optical path. It is in.

Further, the second aspect of the present disclosure is
It is an object detection method executed by an object detection device.
The object detection device is
A floodlight that outputs at least three types of polarization in different polarization directions, and
A light receiving unit that receives the output light of the light projecting unit at at least three different observation polarization angles.
It has a data processing unit that determines whether or not a transparent object exists in the optical path from the light emitting unit to the light receiving unit based on the light receiving signal of the light receiving unit.
The data processing unit
Object detection that executes a stress calculation step to calculate the residual stress of the transparent object by using the light receiving signals of a plurality of different observation polarization angles received by the light receiving unit when it is determined that the transparent object exists in the optical path. In the way.

Further, the third aspect of the present disclosure is
It is a program that executes the object detection process in the object detection device.
The object detection device is
A floodlight that outputs at least three types of polarization in different polarization directions, and
A light receiving unit that receives the output light of the light projecting unit at at least three different observation polarization angles.
It has a data processing unit that determines whether or not a transparent object exists in the optical path from the light emitting unit to the light receiving unit based on the light receiving signal of the light receiving unit.
The program is installed in the data processing unit.
A program for executing a stress calculation step of calculating the residual stress of the transparent object by using the light receiving signals of a plurality of different observation polarization angles received by the light receiving unit when it is determined that the transparent object exists in the optical path. be.

The program of the present disclosure is, for example, a program that can be provided by a storage medium or a communication medium provided in a computer-readable format to an information processing apparatus or a computer system capable of executing various program codes. By providing such a program in a computer-readable format, processing according to the program can be realized on an information processing apparatus or a computer system.

Still other objects, features and advantages of the present disclosure will be clarified by more detailed description based on the examples of the present invention described below and the accompanying drawings. In the present specification, the system is a logical set configuration of a plurality of devices, and the devices of each configuration are not limited to those in the same housing.

According to the configuration of one embodiment of the present disclosure, an apparatus and a method for detecting a transparent object and calculating the residual stress of the transparent object using polarization are realized.
Specifically, for example, it has a light projecting unit that outputs at least three types of different polarizations, a light receiving unit that receives light at at least three types of observation polarization angles, and a data processing unit. The data processing unit stores the light-receiving signal of the light-receiving part in a state where no transparent object exists in the optical path as a reference value, and stores the light-receiving signals of a plurality of different observation polarization angles received by the light-receiving part and the reference value. The presence or absence of a transparent object in the optical path is determined by comparison. Further, when it is determined that a transparent object exists in the optical path, the residual stress of the transparent object is calculated by using the light receiving signals having a plurality of different observation polarization angles received by the light receiving unit.
With this configuration, a device and a method for detecting a transparent object and calculating the residual stress of the transparent object using polarization are realized.
It should be noted that the effects described in the present specification are merely exemplary and not limited, and may have additional effects.

It is a figure which shows one configuration example of the detection process of a transparent object using polarization. It is a figure which shows the optical characteristic of linearly polarized light and elliptically polarized light. It is a block diagram which shows the structural example of the object detection apparatus. It is a figure which shows one structural example of a light projection part. It is a figure which shows one configuration example of a light receiving part. It is a figure explaining an example of a reference value acquisition process. It is a figure explaining an example of the transparent object presence / absence detection processing. It is a figure which shows one structural example of a light projection part. It is a figure which shows one configuration example of a light receiving part. It is a figure which shows one structural example of a light projection part. It is a figure which shows one configuration example of a light receiving part. It is a figure which shows one structural example of a light projection part. It is a figure which shows one configuration example of a light receiving part. It is a figure explaining an example of a reference value acquisition process. It is a figure explaining an example of the transparent object presence / absence detection processing. It is a figure which shows one structural example of a light projection part. It is a figure which shows one configuration example of a light receiving part. It is a figure which shows one structural example of a light projection part. It is a figure which shows one configuration example of a light receiving part. It is a block diagram which shows the structural example of the object detection apparatus. It is a figure which shows one configuration example of a light emitting part and a light receiving part. It is a figure which shows the flowchart explaining the processing sequence executed by the object detection apparatus of this disclosure. It is a figure which shows the flowchart explaining the processing sequence executed by the object detection apparatus of this disclosure. It is a figure which shows the flowchart explaining the processing sequence executed by the object detection apparatus of this disclosure. It is a figure explaining the hardware configuration example of the object detection apparatus.

Hereinafter, the details of the object detection device, the object detection method, and the program of the present disclosure will be described with reference to the drawings. The explanation will be given according to the following items.
1. 1. Detection processing of transparent objects using polarization 2. Stress detection processing using polarization 3. (Example 1) Example 1 of an object detection device that detects a transparent object using polarization and calculates residual stress.
4. (Example 2) Example 2 of an object detection device that detects a transparent object using polarization and calculates residual stress.
5. (Example 3) Example 3 of an object detection device that detects a transparent object using polarization and calculates residual stress.
6. About other examples 7. About the sequence of processing executed by the object detection device 8. About the hardware configuration example of the object detection device 9. Summary of the structure of this disclosure

[1. About detection processing of transparent objects using polarization]
First, the detection process of a transparent object using polarization will be described with reference to FIGS. 1 and the following.
FIG. 1 is a diagram showing a configuration example of a transparent object detection process using polarization.
Light is emitted from the light projecting unit 10 through the polarizing plate 11. This irradiation light is linearly polarized.

When the transparent object 50 is present, the light emitted from the light projecting unit 10 via the polarizing plate 11 passes through the transparent object 50 and is received by the light receiving unit 20 having the polarizing plate 21.
When the transparent object 50 does not exist, the light emitted from the light projecting unit 10 through the polarizing plate 11 is received as it is by the light receiving unit 20 having the polarizing plate 21.

The light emitted from the light projecting unit 10 through the polarizing plate 11 is linearly polarized light.
When the transparent object 50 does not exist, the light receiving unit 20 receives the linearly polarized light.
On the other hand, the transparent object 50 exists, the light passing through the transparent object 50 changes to elliptically polarized light, and the light receiving unit 20 receives the elliptically polarized light.
Based on this difference, the presence or absence of a transparent object can be detected.
Hereinafter, the characteristics of linearly polarized light and elliptically polarized light and the outline of the principle of change from linearly polarized light to elliptically polarized light by a transparent object will be described.

The linearly polarized light emitted from the light projecting unit 10 via the polarizing plate 11 has P-polarized light (or P-wave) and S-polarized light (or S-wave).
Light is an electromagnetic wave and is composed of an electric field and a magnetic field that oscillate orthogonally to the traveling direction.
Here, the light component in which the electric field oscillates in the vertical direction is called P polarization, and the light component in which the electric field oscillates horizontally is called S polarization.
The linear polarization is a polarization having no phase difference between the P polarization and the S polarization, that is, having a characteristic of a phase difference φ = 0.

The optical characteristics of linearly polarized light and elliptically polarized light will be described with reference to FIG.
FIG. 2A is a diagram showing the optical characteristics of linearly polarized light.
FIG. 2A1 is a diagram showing the amplitude characteristics of linearly polarized light, and shows the vibration direction of the electric field at one position in the traveling direction of light, that is, at one point plane (vertical plane) having the Z axis shown in FIG. Shows.
As described above, linear polarization is polarization in which there is no phase difference between P polarization and S polarization and the polarization direction is limited to one plane, and electrolysis is performed on a single plane (vertical plane) having a Z axis shown in FIG. The vibration direction (= locus of the tip of the electric field vector) is a straight line as shown in FIG. 2 (a1).
FIG. 2A2 is a graph showing the correspondence between the observed polarization angle of linearly polarized light and the observed intensity (relative value).
The correspondence between the observed polarization angle of linear polarization and the observed intensity (relative value) is a graph of trigonometric function as shown in FIG. 2 (a2).

As shown in FIG. 1, the linear polarization output from the light projecting unit 10 travels in the space (refractive index N ₁ ) 30 along the Z axis, and is a transparent object (refractive index) having a refractive index different from that of the space 30. It is incident on the index N ₂ ) 50 and passes through the transparent object 50. The passing light that has passed through the transparent object 50 is received by the light receiving unit 20 having the polarizing plate 21.

Linear polarization is elliptically polarized light by incident on a transparent object (refractive index N ₂ ) 50 having a refractive index different from that of space 30 from the space (refractive index N ₁ ) 30 and passing through the transparent object 50. Changes to.

This change from linearly polarized light to elliptically polarized light is due to circular dichroism (CD) based on the material of the transparent object 50.
Circular dichroism (CDs will be briefly described.
Linear polarization can be regarded as the sum of left circular polarization and right circular polarization. That is, the left circular polarization and the right circular polarization pass through the transparent object.
However, many transparent objects have different absorbances for left-handed and right-handed circularly polarized light.
Such a phenomenon in which the absorbance of left-handed circularly polarized light and right-handed circularly polarized light is different is called circular dichroism (CD).

Linear polarization, which is the sum of well-balanced left-circle polarization and right-circle polarization, passes through a transparent object 50 having circular dichroism (CD), and the balance between left-circle polarization and right-circle polarization is lost, resulting in a straight line. It changes from polarized light to elliptically polarized light.

Elliptical polarization is polarization in which a phase difference between P-polarization and S-polarization occurs, and the polarization direction does not become one plane. The direction (= locus of the tip of the electric field vector) is an ellipse as shown in FIG. 2 (b1).
FIG. 2B2 is a graph showing the correspondence between the observed polarization angle of elliptically polarized light and the observed intensity (relative value).
The correspondence between the observed polarization angle of elliptically polarized light and the observed intensity (relative value) is a graph of trigonometric functions as shown in FIG. 2 (b2).

As described above, the light emitted from the light projecting unit 10 through the polarizing plate 11 is linearly polarized light, and when the transparent object 50 does not exist, the light receiving unit 20 receives the linearly polarized light.
On the other hand, the transparent object 50 exists, the light passing through the transparent object 50 changes to elliptically polarized light, and the light receiving unit 20 receives the elliptically polarized light.
Based on this difference, the presence or absence of a transparent object can be detected.

As described above, the phase difference between the linearly polarized P polarization and the S polarization is 0.
On the other hand, the phase difference between the P-polarization and the S-polarization of the elliptically polarized light that has passed through the transparent object 50 is not 0, and the phase difference φ is as shown in (Equation 1) below.

In the above (Equation 1), λ is the wavelength of light, N ₁ is the refractive index of space 30 (= refractive index of air), N ₂ is the refractive index of the transparent object 50, and d is the thickness of the transparent object 50. That's right.

Further, at a point Z having elliptically polarized light that has passed through the transparent object 50,
Vibration in the X direction (vibration of S polarization) = Ax (Z),
Vibration in the Y direction (vibration of P polarization) = Ay (Z),
These Ax (Z) and Ay (Z) can be represented by the following (Equation 2) and (Equation 3).

In the above (Equation 2) and (Equation 3),
A _1X is the amplitude of the elliptically polarized light in the X direction, which is the emitted light (passing light) of the transparent object 50.
A _1Y is the amplitude of the elliptically polarized light in the Y direction, which is the emitted light (passing light) of the transparent object 50.
Is.

Further, the intensity (luminance) of the observed light in the light receiving unit 20 shown in FIG. 1 is calculated by the following (Equation 4) and (Equation 5).
(Equation 4) is the observed luminance when the transparent object 50 does not exist and the linearly polarized light from the light projecting unit 10 is received as it is.
(Equation 5) is the observed luminance when the transparent object 50 exists, the linear polarization from the light projecting unit 10 is changed to elliptically polarized light by the transparent object 50, and the elliptically polarized light is received.
In each of the following (Equation 4) and (Equation 5), the observation luminance I (θ) according to the observation polarization angle (θ) which is the set angle of the polarizing plate 21 provided in the light receiving unit 20 shown in FIG. ) Is a formula for calculating.

In the above (Equation 4) and (Equation 5),
_A0X is the amplitude of linearly polarized light in the X direction that does not pass through the transparent object 50.
_A0Y is the amplitude of linearly polarized light in the Y direction that does not pass through the transparent object 50.
A _1X is the amplitude of the elliptically polarized light in the X direction, which is the emitted light (passing light) of the transparent object 50.
A _1Y is the amplitude of the elliptically polarized light in the Y direction, which is the emitted light (passing light) of the transparent object 50.
Is.

The above (Equation 4) corresponds to the graph of the (a2) polarization angle-intensity characteristic of the linearly polarized light shown in FIG. 2 (a).
The observed luminance I (θ) calculated by (Equation 4) corresponds to the observed intensity of the graph of the (a2) polarization angle-intensity characteristic of the linearly polarized light shown in FIG. 2 (a).
The observed polarization angle (θ) shown in (Equation 4) corresponds to the observed polarization angle (θ) on the horizontal axis of FIG. 2 (a2).
That is, the correspondence between the observed polarization angle (θ) and the observed brightness (I (θ)) of the linear polarization shown by the relational expression of (Equation 4) is a graph of the trigonometric function shown in FIG. 2 (a2).

Further, the above (Equation 5) corresponds to the graph of the (b2) polarization angle-intensity characteristic of the elliptically polarized light shown in FIG. 2 (b).
The observed luminance I (θ) calculated by (Equation 5) corresponds to the observed intensity of the graph of the (b2) polarization angle-intensity characteristic of the elliptically polarized light shown in FIG. 2 (b).
The observed polarization angle (θ) shown in (Equation 5) corresponds to the observed polarization angle (θ) on the horizontal axis of FIG. 2 (b2).
That is, the correspondence between the observed polarization angle (θ) and the observed brightness (I (θ)) of the elliptically polarized light shown by the relational expression of (Equation 5) is a graph of the trigonometric function shown in FIG. 2 (b2).

If the correspondence between the observed polarization angle (θ) obtained based on this observed value and the observed brightness I (θ) corresponds to the trigonometric function graph of linear polarization shown in FIG. 2 (a2), the light received by the light receiving unit 20 The light is linearly polarized, and it can be determined that the transparent object 50 does not exist.
On the other hand, if the correspondence between the observed polarization angle (θ) obtained based on the observed value and the observed brightness I (θ) corresponds to the trigonometric function graph of elliptically polarized light shown in FIG. 2 (b2), the light receiving unit 20 The light received is elliptically polarized light, and it can be determined that the transparent object 50 is present.

The light receiving unit 20 shown in FIG. 1 rotates the polarizing plate 21 to set the observed polarization angle (θ) to an arbitrary angle, and the observed brightness I (θ) at each observed polarization angle (θ) is an observed value. Can be obtained as.
In order to determine whether the observed light corresponds to the above (Equation 4) or (Equation 5) based on the observed value of the light receiving unit 20, it is necessary to observe a plurality of different observation polarization angles (θ). It is necessary to acquire the luminance I (θ) as an observed value.

The unknown number included in the above (Equation 4) is
Amplitude of linearly polarized light in the X direction: A _0X ,
Amplitude of linearly polarized light in the Y direction: A _0Y ,
These two values.
On the other hand, the unknown number included in the above (Equation 5) is
Amplitude of elliptically polarized light in the X direction: A _1X ,
Amplitude of elliptically polarized light in the Y direction: A _1Y ,
Phase difference: φ
These three values.

As described above, when the light receiving unit 20 receives the linearly polarized light according to the above (Equation 4), there are two unknowns, and when the light receiving unit 20 receives the elliptically polarized light according to the above (Equation 5). By acquiring the observation brightness I (θ) corresponding to at least three different observation polarization angles (θ) with three unknowns, a triangle according to any of the above equations (Equation 4) and (Equation 5). It can be determined whether or not the optical signal corresponding to the function graph is received.

That is, in order to determine whether or not the transparent object 50 exists between the light projecting unit 10 and the light receiving unit 20, the light receiving unit 20 rotates the polarizing plate 21 and at least three different observation polarization angles. (Θ) may be set, and the observed brightness I (θ) at each observed polarization angle (θ) may be acquired as an observed value.

In this way, the light received by the light receiving unit 20 is
Is it linearly polarized light that does not pass through the transparent object 50?
Is it elliptically polarized light that has passed through the transparent object 50?
At least 3 points or more are required to be sampled in order to determine.

The device configuration for executing the transparent object detection process and the process sequence will be described in detail later.
In the object detection device of the present disclosure described later, it is possible to execute a detection process using different polarizations in three or more directions and reliably determine the presence or absence of a transparent object.

As a general configuration for detecting the presence or absence of a transparent object, the light projecting unit outputs one linearly polarized light, and the light receiving unit acquires data at a plurality of observed polarization angles for this one linearly polarized light. However, in the configuration of the present disclosure, a plurality of (three or more types) of linearly polarized light having different polarization angles are output in parallel or sequentially in chronological order from the light projecting unit.

On the light receiving unit side, a light receiving signal based on these plurality of linearly polarized light, that is, elliptically polarized light that has passed through a transparent object or linearly polarized light that does not pass through is received.
The light receiving unit side also observes the light receiving signal at a plurality of different observation polarization angles.
By performing such processing, the detection accuracy of transparent objects is improved.
The specific process for determining the presence or absence of a transparent object will be described in detail later.

Transparent objects that pass through the detection area may be set at various angles, and many transparent objects have individual differences such as distortion due to internal materials and stress, etc., and were input to each transparent object. Linear polarization causes different behavior depending on the angle of the transparent object and the difference in the internal material.
Therefore, it is assumed that there may be cases where the change from linear polarization to elliptically polarized light cannot be reliably confirmed with only one linearly polarized light.

In the configuration of the present disclosure, in order to eliminate or reduce such a problem, a plurality of (three or more types) linearly polarized light having different polarization angles are output in parallel or sequentially in chronological order from the light projecting unit. Is configured to be observed on the light receiving part side.
With this configuration, highly accurate detection of transparent objects is realized.

Further, by outputting a plurality of linearly polarized light from the light projecting section and observing them on the light receiving section side in this way, it is possible to simultaneously measure the residual stress inside the transparent object.
In the following items, the measurement process of internal residual stress using polarization will be described.

[2. About stress detection processing using polarization]
As described above, for example, in a factory production line, residual stress is often measured as a quality inspection such as the strength of a molded product such as a resin in addition to the above-mentioned object detection.
If the residual stress is large, there is a high possibility that deformation, cracking, etc. will occur. For example, a resin molded product having a residual stress larger than a specified value is removed from the manufacturing process as a defective product.

As a conventional general method for measuring residual stress, a polarizing plate on the illumination side is rotated to a plurality of angles to irradiate an object, and the transmitted light is passed through a polarizing plate having a polarization angle corresponding to each polarization angle on the illumination side. There is a way to observe.
However, this method requires an accurate rotation control mechanism for the polarizing plate, control of the measurement timing on each light receiving side, and the like, and requires a high-cost and complicated system. In addition, there is a problem that real-time measurement is difficult because it takes time to analyze the observation data.
The residual stress measurement process that solves these problems will be described below.
Residual stress The residual stress (N) of the object to be measured can be calculated by the following formula (Equation 6).

In the above (Equation 6)
N is the residual stress,
α is the photoelastic constant peculiar to the material of the object to be measured,
d is the thickness of the material of the object to be measured,
σ ₁ is the principal stress, which represents the tensile component in the residual stress.
σ ₂ is the principal stress, which represents the compressive component in the residual stress.

If the principal stress σ ₁ , which represents the tensile component in the residual stress, is large, the density of the material decreases and the strength decreases. Further, when the principal stress σ ₂ , which represents the compression component in the residual stress, is large, the density of the material increases and the strength increases.

Due to the distribution of residual stress, strain occurs in the material density inside the material. When polarized light is passed through a substance in which such distortion occurs, the refractive index changes due to the difference in refractive index between the vertical direction and the horizontal direction.
By observing this change, the residual stress of the object to be measured can be measured.
In this embodiment, the object to be measured is a transparent object that transmits light.

A process for measuring the residual stress of the transparent object 50 will be described with reference to the configuration shown in FIG.
The light projecting unit 10 irradiates the transparent object 50, which is the object for measuring the residual stress, with the polarized light at four different angles (0 °, 45 °, 90 °, 135 °) via the polarizing plate 11.

The polarizing plate 11 may be set to have four polarization angles (0 °, 45 °, 90 °, 135 °) as a dividing region, or may be set.
The polarizing plate 11 having a polarization direction in one direction may be sequentially changed in time series to the settings of four polarization angles (0 °, 45 °, 90 °, 135 °).

The four polarizations that have passed through the transparent object 50 are passed through the polarizing plate 21 of the same four types of angles (0 °, 45 °, 90 °, 135 °) set in the light receiving unit 20, respectively, and the light receiving unit 20 is used. Receives light at.
The polarizing plate 21 on the light receiving portion 20 side may also be set to have four polarization angles (0 °, 45 °, 90 °, 135 °) as a dividing region, or may be set.
The polarizing plate 21 having a polarization direction in one direction may be configured to be sequentially changed in time series by setting four polarization angles (0 °, 45 °, 90 °, 135 °).

Let the observed luminance of the four kinds of angles (0 °, 45 °, 90 °, 135 °) received by the light receiving unit 20 be I ₀ , I ₄₅ , I ₉₀ , and I ₁₃₅ .
Using the observed brightness corresponding to these four polarizations, the residual stress (N) calculation formula previously shown in (Equation 6) can be rewritten as the following (Equation 7).

Each parameter shown in the above (Equation 7) is a setting shown in the following (Equation 8) to (Equation 10).

In addition, I _b is the brightness of the background and is a constant.

Further, the stress direction (φ) is indicated by the following (Equation 11).

In this way, the residual stress in the transparent object 50 is used by using the observed brightness (I ₀ , I ₄₅ , I ₉₀ , I ₁₃₅ ) of the polarization at four angles (0 °, 45 °, 90 °, 135 °). And the stress direction can be calculated.

In order to improve the measurement stability of the residual stress, it is preferable to use four polarizations, but theoretically, the residual stress and the stress direction can be calculated even with three polarizations.

As an example, an example of calculation processing of residual stress and stress direction using three polarizations (0 °, 45 °, 90 °) will be described.

The above-mentioned (Equation 8), (Equation 9), and (Equation 11) can be rewritten as the following (Equation 12), (Equation 13), and (Equation 14).

In this way, the residual stress and stress direction in the transparent object 50 are calculated using the observed luminances (I ₀ , I ₄₅ , I ₉₀ ) of the polarizations at three different angles (0 °, 45 °, 90 °). be able to.

Hereinafter, a plurality of specific examples of an apparatus and a processing sequence for executing the presence / absence detection of a transparent object and the detection processing of residual stress will be described.

[3. (Example 1) Example 1 of an object detection device that detects a transparent object using polarization and calculates residual stress]
First, Example 1 of an object detection device that detects a transparent object using polarization and calculates residual stress will be described.

FIG. 3 is a block diagram showing a configuration example of the object detection device 100 of the first embodiment.
As shown in FIG. 3, the object detection device 100 includes an input unit 101, a control unit 102, a storage unit 103, an output unit 104, a light projecting unit 110, a light receiving unit 120, and a data processing unit 130.

Whether or not the transparent object 170 exists in the detection area 150 based on the light receiving signal after the polarization is output from the light projecting unit 110 and the polarized light transmitted through the transparent object 170 passing through the detection area 150 is received by the light receiving unit 120. The presence or absence of the transparent object is determined, and when the transparent object 170 is detected, the residual stress of the transparent object is also calculated.

The input unit 101 is information that triggers processing control by the user such as start and stop of object detection processing, and mode setting information such as a mode of only object detection processing and a mode of executing object detection and stress detection. Input etc.
In addition, it is also used for inputting parameters required for processing such as setting information of polarization to be used, input of threshold values used for object detection, stress calculation processing, and the like.

The control unit 102 controls the processing of the entire object detection device 100, performs processing control for each component, controls execution timing, and the like.
The control unit 102 has, for example, a CPU having a program execution function, and executes processing control according to a program stored in the storage unit 103.

The storage unit 103 stores data based on the signal received by the light receiving unit 120 and data generated and calculated by the data processing unit 130.
Further, it is also used as a storage area for parameters, reference values, threshold values, programs executed by the control unit 102, etc. applied to data processing in the data processing unit 130.

The output unit 104 outputs, for example, the data processing result of the data processing unit 130.
Specifically, the detection information of whether or not a transparent object is detected, the information on the residual stress calculated for the detected transparent object, and the good / defective product of the transparent object determined based on the calculated residual stress. Output information etc.

The light projecting unit 110 includes a light output unit 111 and a polarization generating unit 112.
The light projecting unit 110 has a configuration in which a plurality of (three or more types) linearly polarized light having different polarization angles are output in parallel or sequentially in chronological order.
A specific configuration example of the light projecting unit 110 will be described in detail later.

The light receiving unit 120 has a polarizing plate 121 and a light receiving sensor 122.
The light receiving unit 120 differs from elliptically polarized light, which is the passing light of the transparent object 170 based on a plurality of (three or more types) of linearly polarized light output from the floodlighting unit 110, or linearly polarized light, which is the non-passing light of the transparent object 170. It has a configuration for observing at the observation polarization angle.
The light receiving unit 120 also has a configuration in which a plurality (three or more types) of different observation polarization angles (θ) are set, and the observation brightness I (θ) at each observation polarization angle (θ) is acquired as an observation value.
A specific configuration example of the light receiving unit 120 will be described in detail later.

The data processing unit 130 includes a light receiving signal recording unit 131, an object presence / absence determination unit 132, a stress calculation unit 133, and a stress determination unit 134.

The light receiving signal recording unit 131 inputs a photoelectric conversion signal based on the light received by the light receiving sensor 122 of the light receiving unit 120, and is an input signal necessary for determining whether or not the transparent object 170 exists in the detection area 150. Perform the analysis.

For example, the light receiving signal recording unit 131 inputs the light receiving signal of the light receiving unit 120 in a state where the transparent object 170 does not exist in the detection area 150 as a preliminary preparation process, and calculates a reference value based on the input signal value. , The calculated reference value is stored in the storage unit 103.
This reference value is used to determine the presence or absence of a transparent object in the subsequent actual transparent object presence / absence determination process.
After this reference value acquisition process, the actual transparent object detection process is started.

In the transparent object detection process, when the transparent object 170 exists in the detection area 150 and when it does not exist, the light receiving signal of the light receiving unit 120 is continuously input in various states, and based on this signal value. Then, the signal value for comparison with the previously acquired reference value is calculated.

The object presence / absence determination unit 132 compares the signal value calculated by the light receiving signal recording unit 131 with the reference value stored in the storage unit, and determines whether or not the transparent object 170 exists in the detection area 150. ..
When the difference between the newly acquired signal value and the reference value is larger than the predetermined threshold value, it is determined that the transparent object 170 exists in the detection area 150.
On the other hand, when the difference between the newly acquired signal value and the reference value is not larger than the predetermined threshold value, it is determined that the transparent object 170 does not exist in the detection area 150.

It should be noted that this determination process basically follows the determination process for determining whether the light receiving signal of the light receiving unit 120 is linearly polarized light or elliptically polarized light.
Specifically, for example, as shown in FIG.
(A2) Polarized polarization angle-intensity characteristic signal of linear polarization (b2) Polarized angle-intensity characteristic signal of elliptically polarized light The difference between these signals is calculated using the outputs of a plurality of different polarization angles and the observed values. It is a thing.

The determination result by the object presence / absence determination unit 132 is output to the output unit 104.
In the configuration of the present disclosure, this transparent object presence / absence determination process is executed by utilizing all the polarizations of a plurality of different polarization angles output by the light projecting unit 110. This process reduces the occurrence of problems such as a decrease in detection accuracy depending on the orientation of the transparent object.

When the stress calculation unit 133 determines that the transparent object 170 exists in the detection area 150 as the determination result of the object presence / absence determination unit 132, the residual stress inside the transparent object 170 in the detection area 150 and the residual stress thereof. Calculate the direction.
This stress calculation is based on the item described above [2. It is executed by the process described in [Stress detection process using polarization].
That is, the residual stress inside the transparent object 170 and its direction are calculated by utilizing the polarization of a plurality of (three or more types) different polarization angles output by the light projecting unit 110.

The stress determination unit 134 performs a determination process of determining whether the transparent object 170 is a defective product or a non-defective product based on the residual stress inside the transparent object 170 calculated by the stress calculation unit 133 and its direction.
Specifically, for example, a determination process using a preset determination threshold value is performed. The residual stress inside the transparent object 170 calculated by the stress calculation unit 133 is compared with the direction thereof and the threshold value, and it is determined whether the transparent object 170 is a good product or a defective product.
The determination result is output to the output unit 104.

Next, a specific configuration example of the light projecting unit 110 and the light receiving unit 120 will be described.
As described above, the light projecting unit 110 has a configuration in which a plurality of (three or more types) linearly polarized light having different polarization angles are output in parallel or sequentially in chronological order.
Further, the light receiving unit 120 also has a configuration in which a plurality (three or more types) of different observation polarization angles (θ) are set, and the observation brightness I (θ) at each observation polarization angle (θ) is acquired as an observation value.

As described above, the transparent object 170 passing through the detection region 150 may be set at various angles, and many transparent objects have individual differences such as strain due to internal materials and stress. .. The linear polarization input to each transparent object causes different behavior depending on the angle of the transparent object and the difference in the internal material.
Therefore, it is assumed that there may be cases where the change from linear polarization to elliptically polarized light cannot be reliably confirmed with only one linearly polarized light.

In the configuration of the present disclosure, in order to eliminate or reduce such a problem, a plurality of (three or more types) linearly polarized light having different polarization angles are output in parallel or sequentially in chronological order from the light projecting unit. Is configured to be observed on the light receiving part side.
With this configuration, highly accurate detection of transparent objects is realized.

Hereinafter, a plurality of specific configuration examples of the light emitting unit 110 and the light receiving unit 120 will be described.
FIG. 4 is a diagram showing a configuration example of the light projecting unit 110.
As shown in FIG. 4, the light projecting unit 110 includes a light output unit 111 and a polarization generating unit 112.
FIG. 4 (1) shows a specific configuration example of the polarization generating unit 112.
As shown in FIG. 4 (1), the polarization generating unit 112 of the light projecting unit 110 is composed of a combination of four types of polarizing plates having four types of polarization directions (polarization angles).

Specifically, it is a configuration in which polarizing plates having these four types of polarization directions are combined (0 °, 45 °, 90 °, 135 °).
In FIG. 4 (2), the polarization directions (polarization angles) of the four polarizing plates are indicated by arrows.
As shown in the figure
a = polarization direction 0 °,
b = polarization direction 45 °,
c = polarization direction 90 °,
d = polarization direction 135 °,
The polarization generation unit 112 has a configuration in which polarizing plates having the above four types (a to d) of polarization directions are combined.
With this configuration, the light projecting unit 110 outputs linearly polarized light having four different polarization angles in parallel.

Next, a configuration example of the light receiving unit 120 will be described with reference to FIG.
The light receiving unit 120 receives linearly polarized light having a plurality of different polarization angles output from the above-mentioned light projecting unit 110 via a transparent object or as it is.

The light receiving unit 120 has a configuration in which the observed luminance I (θ) at a plurality of different observed polarization angles (θ) is acquired as an observed value.
FIG. 5 is a diagram showing a configuration example of the light receiving unit 120.
As shown in FIG. 5, the light receiving unit 120 has a polarizing plate 121 and a light receiving sensor 122.
FIG. 5 (1) shows a specific configuration example of the polarizing plate 121.
As shown in FIG. 5 (1), the polarizing plate 121 of the light receiving unit 120 is composed of a combination of four types of polarizing plates having four types of polarization directions (polarization angles).

Specifically, it is a configuration in which polarizing plates having these four types of polarization directions are combined (0 °, 45 °, 90 °, 135 °).
In FIG. 5 (2), the polarization directions (polarization angles) of the four polarizing plates are indicated by arrows.
As shown in the figure
a = polarization direction 0 °,
b = polarization direction 45 °,
c = polarization direction 90 °,
d = polarization direction 135 °,
The polarizing plate 121 has a configuration in which polarizing plates having the above four types (a to d) of polarization directions are combined.

The optical signal via the polarizing plate 121, which is a combination of the polarizing plates having the above four types (a to d) of polarization directions, is input to the light receiving sensor 122 and converted into an electric signal according to the amount of optical signal (light intensity). A photoelectric conversion process is performed, and an electric signal indicating the light intensity is stored in the storage unit 103 and input to the data processing unit 130.
As described above, the light receiving unit 120 has a configuration in which the observed luminance I (θ) at four different observed polarization angles (θ) is acquired as an observed value.

The observed brightness I (θ), which is an observed value at four different observed polarization angles (θ) received by the light receiving unit 120, is stored in the storage unit 103, input to the data processing unit 130, and is transparent in the detection area 150. It is used to determine whether or not the object 170 exists.
Further, when it is determined that the transparent object 170 exists in the detection region 150, it is also used for calculating the residual stress inside the transparent object 170.

Regarding the process executed by using the light projecting unit 110 and the light receiving unit 120 described with reference to FIGS. 4 and 5, that is, a specific determination process of whether or not the transparent object 170 exists in the detection area 150. This will be described with reference to FIGS. 6 and 7.
As described above, as a preliminary preparation process, the light receiving signal recording unit 131 inputs the light receiving signal of the light receiving unit 120 in a state where the transparent object 170 does not exist in the detection area 150, and based on the input signal value. A reference value is calculated, and the calculated reference value is stored in the storage unit 103.
After this reference value acquisition process, the actual detection process is started.

First, a specific example of the reference value acquisition process will be described with reference to FIG.
FIG. 6 is a diagram illustrating the processing of the light receiving signal recording unit 131 for calculating the reference value based on the light receiving signal of the light receiving unit 120.

The user confirms that the transparent object 170 does not exist in the detection area 150, and in this state, inputs a processing start request (trigger signal) from the input unit 101 to start the analysis of the received light signal.
The light receiving unit 120 receives signals having four different observation polarization angles described with reference to FIG. 5, and the light receiving signal is input to the light receiving signal recording unit 131.
The light receiving signal of the light receiving unit 120 is the following signal.
Ia_o = light-receiving signal with an observed polarization angle of 0 ° in the absence of a transparent object Ib_o = light-receiving signal with a polarization angle of 45 ° in the absence of a transparent object Ic_o = light-receiving signal with an observation polarization angle of 90 ° in the absence of a transparent object Signal Id_o = Observed light received signal with a polarization angle of 135 ° in the absence of a transparent object The optical signal analysis unit 131 uses these four signals (Ia_o, Ib_o, Ic_o, Id_o) as reference values (reference signal values) in the storage unit 103. Store.

This reference value is used to determine the presence or absence of a transparent object in the subsequent actual transparent object presence / absence determination process.
After this reference value acquisition process, the actual transparent object detection process is started.

The details of the transparent object detection process will be described with reference to FIG. 7.
In the transparent object detection process, when the transparent object 170 exists in the detection area 150 and when it does not exist, the light receiving signal of the light receiving unit 120 is continuously input in various states, and based on this signal value. Then, the signal value for comparison with the previously acquired reference value is calculated.

The object presence / absence determination unit 132 compares the signal value calculated by the light receiving signal recording unit 131 with the reference value stored in the storage unit, and determines whether or not the transparent object 170 exists in the detection area 150. ..
Let the newly acquired signal value be the following signal value.
Ia = Light-receiving signal with an observed polarization angle of 0 ° Ib = Light-receiving signal with an observed polarization angle of 45 ° Ic = Light-receiving signal with an observed polarization angle of 90 ° Id = Light-receiving signal with an observed polarization angle of 135 °

The object presence / absence determination unit 132 compares these newly acquired signal values with the reference values (Ia_o, Ib_o, Ic_o, Id_o) stored in the storage unit, and determines whether the transparent object 170 exists in the detection area 150. Judge whether or not.

Specifically, for example, a determination process according to the following determination formula is executed.
Received signal values (Ia, Ib, Ic, Id) via the four polarizing plates (a to d) and
Calculate the difference from the reference value (Ia_o, Ib_o, Ic_o, Id_o),
Compare the difference value with the threshold. That is,
(Ia-Ia_o)> Th1a? ... (Judgment formula 11a)
(Ib-Ib_o)> Th1b? ... (Judgment formula 11b)
(Ic-Ic_o)> Th1c? ... (Judgment formula 11c)
(Id-Id_o)> Th1d? ... (Judgment formula 11d)

In the above (judgment formulas 11a to 11d),
Th1a to Th1d are predetermined threshold values.
This threshold value is stored in the storage unit 103.
The determination formulas 11a to 11d are judgment formulas for comparing the difference between the acquired signal value and the reference value at each observed polarization angle with the specified threshold value (Th1a to Th1d).

When any one of the above (determination formulas 11a to 11d) is satisfied, that is,
If even one of the differences between the acquired signal value and the reference value at each observed polarization angle is larger than the predetermined threshold value, it is determined that the transparent object 170 exists in the detection region 150.
On the other hand, when all of the above (determination formulas 11a to 11d) are not satisfied, that is,
If neither the difference between the acquired signal value and the reference value at each observed polarization angle is larger than the predetermined threshold value, it is determined that the transparent object 170 does not exist in the detection region 150.

It should be noted that the process using only one determination formula (determination formula 12) as described below may be executed instead of the above four determination formulas.
(Ia-Ia_o) + (Ib-Ib_o) + (Ic-Ic_o) + (Id-Id_o)> Th1 ... (Determining formula 12)

In the above (judgment formula 12),
Th1 is a predetermined threshold value.
This threshold value is stored in the storage unit 103.
The determination formula 12 is a judgment formula for comparing the sum of the differences between the acquired signal value and the reference value at each observed polarization angle with the threshold value (Th1).

When the above (judgment formula 12) is satisfied, that is,
When the added value of the difference between the acquired signal value and the reference value at each observed polarization angle is larger than the predetermined threshold value (Th1), it is determined that the transparent object 170 exists in the detection region 150.
On the other hand, when the above (determination formula 12) does not hold, that is,
When the sum of the difference between the acquired signal value and the reference value at each observed polarization angle is not larger than the predetermined threshold value (Th1), it is determined that the transparent object 170 does not exist in the detection region 150.

As described above, in the configuration of the present disclosure, the transparent object presence / absence determination process utilizes all the polarizations of the plurality of different polarization angles output by the light projecting unit 110. This process reduces the occurrence of problems such as a decrease in detection accuracy depending on the orientation of the transparent object.
The determination result is output to the output unit 104.

Further, when it is determined that the transparent object 170 exists in the detection area 150, the stress calculation unit 133 calculates the residual stress inside the transparent object 170 in the detection area 150 and its direction. The calculation process of the residual stress and its direction is described in the item described above [2. It is executed by the process described in [Stress detection process using polarization].

The stress determination unit 134 performs a determination process of determining whether the transparent object 170 is a defective product or a non-defective product based on the residual stress inside the transparent object 170 calculated by the stress calculation unit 133 and its direction.
Specifically, for example, a determination process using a preset determination threshold value is performed. The residual stress inside the transparent object 170 calculated by the stress calculation unit 133 is compared with the direction thereof and the threshold value, and it is determined whether the transparent object 170 is a good product or a defective product.
The determination result is output to the output unit 104.

The configuration of the light projecting unit 110 and the light receiving unit 120 is not limited to the configuration described with reference to FIGS. 4 and 5, and various other configurations are possible.
A configuration example of the other light projecting unit 110 and the light receiving unit 120 will be described with reference to FIGS. 8 and 8 and below.

FIG. 8 is a diagram showing a configuration example of the light projecting unit 110.
As described above with reference to FIG. 4, the polarization generating unit 112 of the light projecting unit 110 has four types of polarization directions (0 °, 45 °, 90 °, 135 °) in each of the four divided regions. It is a configuration in which the boards are set one by one and combined.
On the other hand, the polarizing generation unit 112 of the light projecting unit shown in FIG. 8 subdivides the light output region to set a large number of divided regions, and has four types of polarization directions (0 °, 45 °, 90 °, 135). It is a configuration in which a large number of polarizing plates are combined by arranging polarizing plates having °) in each subdivided division region.

FIG. 9 is a diagram showing a configuration example of the light receiving unit 120.
The polarizing plate 121 of the light receiving unit 120 shown in FIG. 9 also has the same configuration as the polarization generating unit 112 of the light projecting unit 110 shown in FIG. It is a configuration in which a large number of polarizing plates are combined by arranging polarizing plates having directions (0 °, 45 °, 90 °, 135 °) in each subdivided division region.

The reference value acquisition process and the transparent object detection process are performed using the received light signal values received through all the polarizing plates of the polarizing plate 121.
For example, in the reference value acquisition process, the user confirms that the transparent object 170 does not exist in the detection area 150, inputs a process start request (trigger signal) from the input unit 101 in this state, and analyzes the received light signal. To start.
The light receiving unit 120 receives a plurality of signals having four different observation polarization angles described with reference to FIG. 9, and inputs the light receiving signals to the light receiving signal recording unit 131.

The light receiving signal recording unit 131 calculates the following signal values and uses them as reference values (reference signals).
Reference value: Ia_o = Addition value of multiple received light signals with an observed polarization angle of 0 ° in the absence of a transparent object.
Reference value: Ib_o = Addition value of multiple received light signals with an observed polarization angle of 45 ° in the absence of a transparent object.
Reference value: Ic_o = Addition value of multiple received light signals with an observed polarization angle of 90 ° in the absence of a transparent object.
Reference Tsu: Id_o = Addition value of multiple received light signals with an observed polarization angle of 135 ° in the absence of a transparent object.
The optical signal analysis unit 131 stores these four signals (Ia_o, Ib_o, Ic_o, Id_o) as reference values (reference signal values) in the storage unit 103.

This reference value is used to determine the presence or absence of a transparent object in the subsequent actual transparent object presence / absence determination process.

In the transparent object presence / absence determination process using the reference value, four determination processes are performed as follows.
(1) Comparison processing between the added value of a plurality of received light signals having an observed polarization angle of 0 °: Ia and the reference value: Ia_o, that is, whether or not the difference between Ia-Ia_o is larger than the specified threshold value Th1a. judge.
(2) Comparison processing between the added value of a plurality of received light signals having an observed polarization angle of 45 °: Ib and the reference value: Ib_o, that is, whether or not the difference between Ib-Ib_o is larger than the specified threshold value Th1b. judge.
(3) Comparison processing between the added value of a plurality of received light signals having an observed polarization angle of 90 °: Ic and the reference value: Ic_o, that is, whether or not the difference between Ic-Ic_o is larger than the specified threshold value Th1c. judge.
(4) Comparison processing between the added value of a plurality of received light signals having an observed polarization angle of 135 °: Id and the reference value: Id_o, that is, whether or not the difference between Id-Id_o is larger than the specified threshold value Th1d. judge.

In any one of these determination processes, if the difference is larger than the specified threshold values Th1a to Th1d, it is determined that the transparent object exists.
On the other hand, when all the differences are not larger than the specified threshold values Th1a to Th1d, it is determined that the transparent object does not exist.

As described above with reference to FIG. 7, the light-receiving signal corresponding to each observed polarization angle is not a comparison determination process between each of the four light-receiving signals corresponding to the four types of observed polarization angles and the threshold value. The addition value of the difference between the addition value and the reference value may be calculated, and a process of determining the presence or absence of a transparent object may be performed based on the comparison between the addition value and one threshold value Th1.

FIG. 10 is a diagram showing another configuration example of the light projecting unit 110.
The light projecting unit 110 shown in FIG. 10 has a configuration in which polarized light having four types of polarization directions (0 °, 45 °, 90 °, 135 °) is sequentially output in chronological order.
The polarization generating unit 112 of the light projecting unit 110 shown in FIG. 10 is composed of, for example, one polarizing plate, and the polarizing plate is rotated by a predetermined angle (45 °) with the passage of time.
By this processing, the polarization having four kinds of polarization directions (0 °, 45 °, 90 °, 135 °) is sequentially output in chronological order.

FIG. 11 is a diagram showing a configuration example of the light receiving unit 120.
The polarizing plate 121 of the light receiving unit 120 shown in FIG. 11 is also composed of, for example, one polarizing plate in the same manner as the configuration of the polarization generating unit 112 of the light projecting unit 110 shown in FIG. , Rotate by a predetermined angle (45 °).
By this processing, the polarizations having four kinds of polarization directions (0 °, 45 °, 90 °, 135 °) are sequentially input in chronological order.

When the configuration shown in FIG. 11 is used, in the reference value acquisition process and the transparent object detection process, the polarizing plate 121 is set to four different polarization angles and the signal acquisition process is executed four times. This is set as one set, and execution is performed using the received light signal values in units of one set.

The reference signals are the following signals: Ia_o = light-receiving signal with an observed polarization angle of 0 ° in the absence of a transparent object Ib_o = light-receiving signal with an observation polarization angle of 45 ° in the absence of a transparent object Ic_o = a transparent object Light-receiving signal with an observed polarization angle of 90 ° without a transparent object Id_o = Light-receiving signal with an observation polarization angle of 135 ° without a transparent object

In the transparent object presence / absence determination process, the difference between the light receiving signal values (Ia, Ib, Ic, Id) via the four types of polarizing plates (a to d) and the reference values (Ia_o, Ib_o, Ic_o, Id_o) is calculated. do,
Compare the difference value with the threshold. That is,
(Ia-Ia_o)> Th1a? ... (Judgment formula 11a)
(Ib-Ib_o)> Th1b? ... (Judgment formula 11b)
(Ic-Ic_o)> Th1c? ... (Judgment formula 11c)
(Id-Id_o)> Th1d? ... (Judgment formula 11d)
The above-mentioned determination formula is the same determination formula as described with reference to FIG. 7.

Alternatively, as described with reference to FIG. 7, a process using only one determination formula (determination formula 12) such as the following may be executed.
(Ia-Ia_o) + (Ib-Ib_o) + (Ic-Ic_o) + (Id-Id_o)> Th1 ... (Determining formula 12)

The light emitting unit 110 and the light receiving unit 120 of the object detection device 100 shown in FIG. 3 can have various configurations as shown in FIGS. 4 to 11, for example.
In any configuration, the floodlight unit 110 outputs linearly polarized light having four different polarization angles in parallel or sequentially in chronological order.
The light receiving unit 120 observes a light receiving signal based on these plurality of linearly polarized light, that is, elliptically polarized light that has passed through a transparent object or linearly polarized light that has not passed through, at a plurality of observed polarization angles.
By performing such processing, the detection accuracy of transparent objects is improved.

[4. (Example 2) Example 2 of an object detection device that detects a transparent object using polarization and calculates residual stress]
Next, Example 2 of an object detection device that detects a transparent object using polarization and calculates residual stress will be described.

The overall configuration of the object detection device of the second embodiment has the same configuration as the object detection device 100 shown in FIG. 3, as in the first embodiment.
In the second embodiment, the configurations of the light projecting unit 110 and the light receiving unit 120 are different from the configurations of the first embodiment.

In the first embodiment, as described with reference to FIGS. 4 to 11.
The light projecting unit 110 is configured to output four types of polarization having four types of polarization directions (polarization angles).
The light receiving unit 120 also has a configuration in which the observed luminance I (θ) at four different observed polarization angles (θ) is acquired as an observed value.

On the other hand, in Example 2,
The light projecting unit 110 is configured to output three types of polarization having three types of polarization directions (polarization angles).
The light receiving unit 120 is also configured to acquire the observed luminance I (θ) at three different observed polarization angles (θ) as an observed value.

Hereinafter, a plurality of specific configuration examples of the light emitting unit 110 and the light receiving unit 120 in the second embodiment will be described.
FIG. 12 is a diagram showing a configuration example of the light projecting unit 110.
As shown in FIG. 12, the light projecting unit 110 includes a light output unit 111 and a polarization generating unit 112.
FIG. 12 (1) shows a specific configuration example of the polarization generating unit 112.
As shown in FIG. 12 (1), the polarization generating unit 112 of the light projecting unit 110 is composed of a combination of three types of polarizing plates having four types of polarization directions (polarization angles).

Specifically, it is a configuration in which polarizing plates having these three types of polarization directions are combined (0 °, 45 °, 90 °).
In FIG. 12 (2), the polarization directions (polarization angles) of the three polarizing plates are indicated by arrows.
As shown in the figure
a = polarization direction 0 °,
b = polarization direction 45 °,
c = polarization direction 90 °,
The polarization generation unit 112 has a configuration in which polarizing plates having the above three types (a to c) of polarization directions are combined.
With this configuration, the light projecting unit 110 outputs linearly polarized light having three different polarization angles in parallel.

Next, a configuration example of the light receiving unit 120 will be described with reference to FIG.
The light receiving unit 120 receives linearly polarized light having a plurality of different polarization angles output from the above-mentioned light projecting unit 110 via a transparent object or as it is.

The light receiving unit 120 has a configuration in which the observed luminance I (θ) at a plurality of different observed polarization angles (θ) is acquired as an observed value.
FIG. 13 is a diagram showing a configuration example of the light receiving unit 120.
As shown in FIG. 13, the light receiving unit 120 has a polarizing plate 121 and a light receiving sensor 122.
FIG. 13 (1) shows a specific configuration example of the polarizing plate 121.
As shown in FIG. 13 (1), the polarizing plate 121 of the light receiving unit 120 is composed of a combination of three types of polarizing plates having three types of polarization directions (polarization angles).

Specifically, it is a configuration in which polarizing plates having these three types of polarization directions are combined (0 °, 45 °, 90 °).
In FIG. 13 (2), the polarization directions (polarization angles) of the three polarizing plates are indicated by arrows.
As shown in the figure
a = polarization direction 0 °,
b = polarization direction 45 °,
c = polarization direction 90 °,
The polarizing plate 121 has a configuration in which polarizing plates having the above three types (a to c) of polarization directions are combined.

The optical signal via the polarizing plate 121, which is a combination of the polarizing plates having the above three types (a to c) of polarization directions, is input to the light receiving sensor 122 and converted into an electric signal according to the amount of optical signal (light intensity). A photoelectric conversion process is performed, and an electric signal indicating the light intensity is stored in the storage unit 103 and input to the data processing unit 130.
As described above, the light receiving unit 120 has a configuration in which the observed luminance I (θ) at three different observed polarization angles (θ) is acquired as an observed value.

The observed brightness I (θ), which is an observed value at three different observed polarization angles (θ) received by the light receiving unit 120, is stored in the storage unit 103, input to the data processing unit 130, and is transparent in the detection area 150. It is charged to determine whether or not the object 170 exists.
Further, when it is determined that the transparent object 170 exists in the detection region 150, it is also used for calculating the residual stress inside the transparent object 170.

Regarding the process executed by using the light projecting unit 110 and the light receiving unit 120 described with reference to FIGS. 12 and 13, that is, a specific determination process of whether or not the transparent object 170 exists in the detection area 150. This will be described with reference to FIGS. 14 and 15.
As described above, as a preliminary preparation process, the light receiving signal recording unit 131 inputs the light receiving signal of the light receiving unit 120 in a state where the transparent object 170 does not exist in the detection area 150, and based on the input signal value. A reference value is calculated, and the calculated reference value is stored in the storage unit 103.
After this reference value acquisition process, the actual detection process is started.

First, a specific example of the reference value acquisition process will be described with reference to FIG.
FIG. 14 is a diagram illustrating the processing of the light receiving signal recording unit 131 for calculating the reference value based on the light receiving signal of the light receiving unit 120.

The user confirms that the transparent object 170 does not exist in the detection area 150, and in this state, inputs a processing start request (trigger signal) from the input unit 101 to start the analysis of the received light signal.
The light receiving unit 120 receives signals having three different observation polarization angles described with reference to FIG. 13, and the light receiving signal is input to the light receiving signal recording unit 131.
The light receiving signal of the light receiving unit 120 is the following signal.
Ia_o = Light-receiving signal with an observed polarization angle of 0 ° in the absence of a transparent object Ib1_o = Light-receiving signal with a polarization angle of 45 ° in the absence of a transparent object Ib2_o = Light-receiving signal with an observation polarization angle of 45 ° in the absence of a transparent object Signal Ic_o = Observed light received signal with a polarization angle of 90 ° in the absence of a transparent object The optical signal analysis unit 131 uses these four signals (Ia_o, Ib1_o, Ib2_o, Ic_o) as reference values (reference signal values) in the storage unit 103. Store.

This reference value is used to determine the presence or absence of a transparent object in the subsequent actual transparent object presence / absence determination process.
After this reference value acquisition process, the actual detection process is started.

The details of the detection process will be described with reference to FIG.
In the detection process, when the transparent object 170 exists in the detection area 150 and when it does not exist, the light receiving signal of the light receiving unit 120 is continuously input in various states, and based on this signal value, the light receiving signal is continuously input. The signal value for comparison with the previously acquired reference value is calculated.

The object presence / absence determination unit 132 compares the signal value calculated by the light receiving signal recording unit 131 with the reference value stored in the storage unit, and determines whether or not the transparent object 170 exists in the detection area 150. ..
Let the newly acquired signal value be the following signal value.
Ia = Light-receiving signal with an observed polarization angle of 0 ° Ib1 = Light-receiving signal with an observed polarization angle of 45 ° Ib2 = Light-receiving signal with an observed polarization angle of 45 ° Ic = Light-receiving signal with an observed polarization angle of 90 °

The object presence / absence determination unit 132 compares these newly acquired signal values with the reference values (Ia_o, Ib1_o, Ib2_o, Ic_o) stored in the storage unit, and determines whether the transparent object 170 exists in the detection area 150. Judge whether or not.

Specifically, for example, a determination process according to the following determination formula is executed.
Received signal values (Ia, Ib1, Ib2, Ic) via the four polarizing plates (a to d) and
Calculate the difference from the reference value (Ia_o, Ib1_o, Ib2_o, Ic_o),
Compare the difference value with the threshold. That is,
(Ia-Ia_o)> Th2a? ... (Judgment formula 21a)
(Ib1-Ib1_o)> Th2b1? ... (Judgment formula 21b1)
(Ib2-Ib2_o)> Th2b2? ... (Judgment formula 21b2)
(Ic-Ic_o)> Th2c? ... (Judgment formula 21c)

In the above determination formulas 21a, 21b1, 21b2, 21c,
Th2a, Th2b1, Th2b2, Th2c are predetermined threshold values.
This threshold value is stored in the storage unit 103.
The determination formulas 21a to 21c are determination formulas for comparing the difference between the acquired signal value and the reference value at each observed polarization angle and the threshold value (Th2a to Th2c).

When any one of the above (determination formulas 21a to 21c) holds, that is,
When the difference between the acquired signal value and the reference value at each observed polarization angle is larger than the predetermined threshold value, it is determined that the transparent object 170 exists in the detection region 150.
On the other hand, when all of the above (determination formulas 21a to 21c) are not satisfied, that is,
If neither the difference between the acquired signal value and the reference value at each observed polarization angle is larger than the predetermined threshold value, it is determined that the transparent object 170 does not exist in the detection region 150.

It should be noted that the process using only one determination formula (determination formula 22) as described below may be executed instead of the above four determination formulas.
(Ia-Ia_o) + (Ib1-Ib1_o) + (Ib2-Ib2_o) + (Ic-Ic_o)> Th2 ... (Determining formula 22)

In the above (judgment formula 22)
Th2 is a predetermined threshold value.
This threshold value is stored in the storage unit 103.
The determination formula 22 is a determination formula for comparing the sum of the differences between the acquired signal value and the reference value at each observed polarization angle with the threshold value (Th2).

When the above (judgment formula 22) is satisfied, that is,
When the added value of the difference between the acquired signal value and the reference value at each observed polarization angle is larger than the predetermined threshold value (Th2), it is determined that the transparent object 170 exists in the detection region 150.
On the other hand, when the above (determination formula 22) does not hold, that is,
When the added value of the difference between the acquired signal value and the reference value at each observed polarization angle is not larger than the predetermined threshold value (Th2), it is determined that the transparent object 170 does not exist in the detection region 150.

As described above, in the configuration of the present disclosure, the transparent object presence / absence determination process utilizes all the polarizations of the plurality of different polarization angles output by the light projecting unit 110. This process reduces the occurrence of problems such as a decrease in detection accuracy depending on the orientation of the transparent object.
The determination result is output to the output unit 104.

Further, when it is determined that the transparent object 170 exists in the detection area 150, the stress calculation unit 133 calculates the residual stress inside the transparent object 170 in the detection area 150 and its direction. Items explained earlier [2. It is executed by the process described in [Stress detection process using polarization].
The stress determination unit 134 performs a determination process of determining whether the transparent object 170 is a defective product or a non-defective product based on the residual stress inside the transparent object 170 calculated by the stress calculation unit 133 and its direction.
Specifically, for example, a determination process using a preset determination threshold value is performed. The residual stress inside the transparent object 170 calculated by the stress calculation unit 133 is compared with the direction thereof and the threshold value, and it is determined whether the transparent object 170 is a good product or a defective product.
The determination result is output to the output unit 104.

Other configuration examples of the light projecting unit 110 and the light receiving unit 120 in the second embodiment will be described with reference to FIGS. 16 and below.

FIG. 16 is a diagram showing a configuration example of the light projecting unit 110.
As described above with reference to FIG. 12, the polarization generating unit 112 of the light projecting unit 110 has one polarizing plate having three types of polarization directions (0 °, 45 °, 90 °) in each of the four divided regions. It is a configuration that is set and combined one by one.
On the other hand, the polarizing generation unit 112 of the light projecting unit shown in FIG. 16 subdivides the light output region to set a large number of divided regions, and sets three types of polarization directions (0 °, 45 °, 90 °). It is a configuration in which a large number of polarizing plates are combined by arranging the polarizing plates having the same in each subdivided area.

FIG. 17 is a diagram showing a configuration example of the light receiving unit 120.
The polarizing plate 121 of the light receiving unit 120 shown in FIG. 17 also has the same configuration as the polarization generating unit 112 of the light projecting unit 110 shown in FIG. It is a configuration in which a large number of polarizing plates are combined by arranging polarizing plates having directions (0 °, 45 °, 90) in each subdivided division region.

The reference value acquisition process and the transparent object detection process are performed using the received light signal values received through all the polarizing plates of the polarizing plate 121.
For example, in the reference value acquisition process, the user confirms that the transparent object 170 does not exist in the detection area 150, inputs a process start request (trigger signal) from the input unit 101 in this state, and analyzes the received light signal. To start.
The light receiving unit 120 receives a plurality of signals having three different observation polarization angles described with reference to FIG. 17, and inputs the light receiving signal to the light receiving signal recording unit 131.

The light receiving signal recording unit 131 calculates the following signal values and uses them as reference values (reference signals).
Reference value: Ia_o = Addition value of multiple received light signals with an observed polarization angle of 0 ° in the absence of a transparent object.
Reference value: Ib1_o = Addition value of multiple received light signals with an observed polarization angle of 45 ° in the absence of a transparent object.
Reference value: Ib2_o = Addition value of multiple received light signals with an observed polarization angle of 45 ° in the absence of a transparent object.
Reference value: Ic_o = Addition value of multiple received light signals with an observed polarization angle of 90 ° in the absence of a transparent object.
The optical signal analysis unit 131 stores these four signals (Ia_o, Ib1_o, Ib2_o, Ic_o) as reference values (reference signal values) in the storage unit 103.

This reference value is used to determine the presence or absence of a transparent object in the subsequent actual transparent object presence / absence determination process.

In the transparent object presence / absence determination process using the reference value, four determination processes are performed as follows.
(1) Comparison processing between the added value of a plurality of received light signals having an observed polarization angle of 0 °: Ia and the reference value: Ia_o, that is, whether or not the difference between Ia-Ia_o is larger than the specified threshold value Th2a. judge.
(2) Comparison processing between the added value of a plurality of received light signals having an observed polarization angle of 45 °: Ib1 and the reference value: Ib1_o, that is, whether or not the difference between Ib1-Ib1_o is larger than the specified threshold value Th2b1. judge.
(3) Comparison processing between the added value of a plurality of received light signals having an observed polarization angle of 45 °: Ib2 and the reference value: Ib2_o, that is, whether or not the difference between Ib2-Ib2_o is larger than the specified threshold value Th2b2. judge.
(4) Comparison processing between the added value of a plurality of received light signals having an observed polarization angle of 90 °: Ic and the reference value: Ic_o, that is, whether or not the difference between Ic-Ic_o is larger than the specified threshold value Th2c. judge.

In any one of these determination processes, if the difference is larger than the specified threshold values Th2a to Th2c, it is determined that the transparent object exists.
On the other hand, when all the differences are not larger than the specified threshold values Th2a to Th2c, it is determined that the transparent object does not exist.

As described above with reference to FIG. 15, the light-receiving signal corresponding to each observed polarization angle is not a comparison determination process between each of the four light-receiving signals corresponding to the three types of observed polarization angles and the threshold value. The addition value of the difference between the addition value and the reference value may be calculated, and a process of determining the presence or absence of a transparent object may be performed based on the comparison between the addition value and one threshold value Th2.

FIG. 18 is a diagram showing another configuration example of the light projecting unit 110.
The light projecting unit 110 shown in FIG. 18 has a configuration in which polarized light having three types of polarization directions (0 °, 45 °, 90 °) is sequentially output in chronological order.
The polarization generating unit 112 of the light projecting unit 110 shown in FIG. 18 is composed of, for example, one polarizing plate, and the polarizing plate is rotated by a predetermined angle (45 °) with the passage of time.
By this processing, the polarization having three kinds of polarization directions (0 °, 45 °, 90 °) is sequentially output in chronological order.

FIG. 19 is a diagram showing a configuration example of the light receiving unit 120.
The polarizing plate 121 of the light receiving unit 120 shown in FIG. 19 is also composed of, for example, one polarizing plate in the same manner as the configuration of the polarization generating unit 112 of the light projecting unit 110 shown in FIG. , Rotate by a predetermined angle (45 °).
By this processing, the polarizations having three kinds of polarization directions (0 °, 45 °, 90 °) are sequentially input in chronological order.

When the configuration shown in FIG. 19 is used, in the reference value acquisition process and the transparent object detection process, the polarizing plate 121 is set to three different polarization angles and the signal acquisition process is executed three times. This is set as one set, and execution is performed using the received light signal values in units of one set.

The reference signals are the following signals: Ia_o = light-receiving signal with an observed polarization angle of 0 ° in the absence of a transparent object Ib_o = light-receiving signal with an observation polarization angle of 45 ° in the absence of a transparent object Ic_o = a transparent object Received signal with an observed polarization angle of 90 ° in the absence

In the transparent object presence / absence determination process, the difference between the received light signal values (Ia, Ib, Ic) via the three types of polarizing plates (a to c) and the reference values (Ia_o, Ib_o, Ic_o) is calculated.
Compare the difference value with the threshold. That is,
(Ia-Ia_o)> Th2a? ... (Judgment formula 21a)
(Ib-Ib_o)> Th2b? ... (Judgment formula 21b)
(Ic-Ic_o)> Th2c? ... (Judgment formula 21c

Alternatively, a process using only one determination formula (determination formula 22) as described below may be executed.
(Ia-Ia_o) + (Ib-Ib_o) + (Ic-Ic_o)> Th2 ... (Judgment formula 23)

As described above, the light emitting unit 110 and the light receiving unit 120 of the object detection device 100 shown in FIG. 3 can have various configurations as shown in FIGS. 12 to 19, for example.
In any configuration, the light projecting unit 110 outputs linearly polarized light having three different types of polarization angles in parallel or sequentially outputs them in chronological order.
The light receiving unit 120 observes a light receiving signal based on these plurality of linearly polarized light, that is, elliptically polarized light that has passed through a transparent object or linearly polarized light that has not passed through, at a plurality of observed polarization angles.
By performing such processing, the detection accuracy of transparent objects is improved.

[5. (Example 3) Example 3 of an object detection device that detects a transparent object using polarization and calculates residual stress]
Next, Example 3 of an object detection device that detects a transparent object using polarization and calculates residual stress will be described.

FIG. 20 shows a configuration example of the object detection device 200 of the third embodiment.
As shown in FIG. 20, the object detection device 200 includes an input unit 101, a control unit 102, a storage unit 103, an output unit 104, a light projecting unit 110, a light receiving unit 120, and a data processing unit 130.
These configurations and processes are the same as the configurations and processes described with reference to the first and second embodiments.

In the configuration of the third embodiment, as shown in FIG. 20, the polarization posted by the light projecting unit 110 is reflected by the reflector 180 through the detection region, and the reflected light is received by the light receiving unit 120. It has become.
Only the configuration using the reflector 180 is different from the first and second embodiments.

Similar to the first and second embodiments described above, the light projecting unit 110 and the light receiving unit 120 are configured to output four or three different types of polarized light and receive light.

[6. About other examples]
Next, other examples will be described.
Various configurations of the light emitting unit and the light receiving unit have been described with reference to FIGS. 4 to 19, but in addition to these configurations, for example, polarized light having a different wavelength is output from the light emitting unit, and the light receiving unit side also outputs the polarized light. It may be configured to observe the polarization corresponding to each wavelength.

A specific example will be described with reference to FIG.
As shown in FIG. 21, the output light passing through the polarizing plate of the light projecting unit 110 is defined as light having three different wavelengths of R (red) G, (green), and B (blue), and each of the wavelength lights is polarized. The angle is configured to output four polarizations (0 °, 45 °, 90 °, 135 °).

Also on the light receiving unit 120 side, the observed light has three different wavelengths of R (red) G, (green), and B (blue), and the polarization angles of each wavelength light are (0 °, 45 °, 90). The configuration is such that four polarizations (°, 135 °) are observed.

As described above with reference to (Equation 1), the phase difference φ of the elliptically polarized light generated by the linear polarization passing through the transparent object depends on the wavelength λ of the light.
That is, different elliptically polarized light is generated depending on the wavelength. By observing these, it is possible to observe different elliptically polarized light according to the wavelength, and it is possible to further improve the detection accuracy.

[7. About the sequence of processing executed by the object detection device]
Next, a sequence of processes executed by the object detection device described in each of the above-described embodiments will be described.

The sequence of processing executed by the object detection device shown in FIG. 3 or FIG. 20 will be described with reference to the flowchart of FIG. 22 and below.
The process according to the flowchart shown in FIGS. 22 and 22 is executed under the control unit 102 of the object detection device shown in FIG. 3 or FIG.
For example, it is executed under the control of a control unit 102 having a CPU or the like having a program execution function according to a program stored in the storage unit 103.

The flowchart shown in FIG. 22 is a flowchart illustrating the entire sequence of processes executed by the object detection device.
The flowchart shown in FIG. 23 is a flowchart illustrating a detailed sequence of the reference value acquisition process and the transparent object detection process in steps S101 to S102 of the flow shown in FIG. 22.
The flowchart shown in FIG. 24 is a flowchart illustrating a detailed sequence of the residual stress calculation process in step S105 of the flow shown in FIG. 22.

First, the entire sequence of processes executed by the object detection device will be described with reference to the flowchart shown in FIG.
Hereinafter, the processing of each step will be described in sequence.

(Step S101)
First, in step S101, the reference value acquisition process is executed.
This reference value is
As a preliminary preparation process, the light receiving signal recording unit 131 inputs the light receiving signal of the light receiving unit 120 in a state where the transparent object 170 does not exist in the detection area 150, calculates a reference value based on the input signal value, and calculates it. The reference value is stored in the storage unit 103.
This reference value is used to determine the presence or absence of a transparent object in the subsequent actual transparent object presence / absence determination process.
After this reference value acquisition process, the actual detection process is started.

(Step S102)
Next, in step S102, the transparent object detection process is executed.
This process is a process for detecting whether or not the transparent object 170 exists in the polarization passing region in the detection region 20 shown in FIGS. 3 and 20.
This process is executed by the light receiving signal recording unit 131 of the data processing unit 130 and the object presence / absence determination unit 132 based on the optical signal received by the light receiving unit 120.
This specific processing sequence will be described later with reference to the flowchart shown in FIG. 23.

(Step S103)
When the transparent object detection process is completed in step S102, the result information of the transparent object detection process is output to the output unit 104 in step S103.

(Step S104)
The next step S104 is a branching process for determining the next process depending on whether or not a transparent object is detected as a result of the transparent object detection process in step S102.
If a transparent object is detected in the transparent object detection process in step S102, the process proceeds to step S105.
On the other hand, if the transparent object is not detected, the process returns to step S102 and the transparent object detection process is continued.

(Step S105)
If a transparent object is detected in the transparent object detection process in step S102, the process proceeds to step S105, and in step S105, the residual stress detection process for the detected transparent object is executed.
This process is performed by the item described above [2. It is executed by the process described in [Stress detection process using polarization].
A specific processing sequence will be described later with reference to the flowchart shown in FIG. 24.

(Step S106)
When the residual stress detection process for the transparent object is completed in step S105, the result information of the residual stress detection process for the transparent object is output to the output unit 104 in step S106.

Next, with reference to the flowchart shown in FIG. 23, a detailed sequence of the reference value acquisition process and the transparent object detection process in steps S101 to S102 of the flow shown in FIG. 22 will be described.

(Step S201)
First, in step S201, the light receiving signal of the light receiving unit 120 is input to the light receiving signal recording unit 131 of the data processing unit 130.

(Step S202)
Next, in step S202, the light receiving signal recording unit 131 that has input the light receiving signal of the light receiving unit 120 generates a reference value based on the signal received by the light receiving unit 120 in a state where the transparent object does not exist in the detection area 150. It is stored in the storage unit 103.

The method of generating the reference value differs depending on the configuration of the light projecting unit 110 and the light receiving unit 120.
The configurations of the light projecting unit 110 and the light receiving unit 120 are various as described above with reference to FIGS. 4 to 19, and the light receiving signal recording unit 131 is described with reference to FIGS. 4 to 19. A reference value (reference signal) corresponding to the configuration of the light projecting unit 110 and the light receiving unit 120 is generated and stored in the storage unit 103.

(Step S203)
When the reference value acquisition process in step S202 is completed, the transparent object detection process is then started in step S203.

(Steps S204 to S208)
Next, in step S204, the light receiving signal of the light receiving unit 120 is acquired and input to the light receiving signal recording unit 131 of the data processing unit 130.

In step S205, the light receiving signal recording unit 131 continuously inputs the light receiving signal of the light receiving unit 120 in various states when the transparent object 170 exists in the detection area 150 and when it does not exist. Based on the signal value, the signal value for comparison with the previously acquired reference value is calculated.

Further, in steps S205 to S206, the object presence / absence determination unit 132 compares the signal value calculated by the light receiving signal recording unit 131 with the reference value stored in the storage unit, and the transparent object 170 is generated in the detection area 150. Determine if it exists.

If the difference between the newly acquired signal value and the reference value is larger than the predetermined threshold value, that is, if the determination in step S206 is Yes, the process proceeds to step S207, and it is determined that the transparent object 170 exists in the detection area 150. do.

On the other hand, if the difference between the newly acquired signal value and the reference value is not larger than the predetermined threshold value, that is, if the determination in step S206 is No, the process proceeds to step S208, and is a transparent object in the detection area 150. It is determined that 170 does not exist.

After these determination processes, the determination result is output to the output unit 104, further returns to step S203, and the transparent object detection process is continuously executed.

Next, the details of the detailed sequence of the residual stress calculation process in step S105 of the flow shown in FIG. 22 will be described with reference to the flowchart shown in FIG. 24.

(Step S301)
First, in step S301, the light receiving signal of the light receiving unit 120 is input to the stress calculation unit 133 of the data processing unit 130.

(Step S302)
Next, in step S302, the stress calculation unit 133 calculates the residual stress and the stress direction of the transparent object by using the input signal.
This stress calculation is based on the item described above [2. It is executed by the process described in [Stress detection process using polarization].
That is, the residual stress inside the transparent object 170 and its direction are calculated by utilizing the polarization of a plurality of (three or more types) different polarization angles output by the light projecting unit 110.
The calculation result is output to the stress determination unit 134.

(Steps S303 to S306)
Next, in steps S303 to S304, the stress determination unit 134 compares the residual stress inside the transparent object 170 input from the stress calculation unit 133 with the direction information thereof and a predetermined threshold value, and the transparent object 170 is a non-defective product. It is determined whether it is a defective product or a defective product.

If it is determined to be a defective product, the process proceeds to step S305, and the determination result of the defective product is output to the output unit 104.
On the other hand, if it is determined that the product is not defective, the process proceeds to step S306, and the determination result that the product is not defective is output to the output unit 104.

[8. About the hardware configuration example of the object detection device]
Next, a hardware configuration example of the object detection device will be described with reference to FIG. 25.
The hardware configuration shown in FIG. 25 is a block diagram showing an example of a hardware configuration that can be used as the object detection device described in the above-described embodiment.

The CPU (Central Processing Unit) 301 functions as a data processing unit that executes various processes according to a program stored in the ROM (Read Only Memory) 302 or the storage unit 308. For example, the process described in the above-described embodiment is executed. The RAM (Random Access Memory) 303 stores programs and data executed by the CPU 301. These CPU 301, ROM 302, and RAM 303 are connected to each other by a bus 304.

The CPU 301 is connected to the input / output interface 305 via the bus 304, and the input / output interface 305 is connected to an input unit 306 including various switches, a keyboard, a mouse, a microphone, etc., and an output unit 307 including a display, a speaker, and the like. There is.
The CPU 301 executes various processes in response to commands input from the input unit 306, and outputs the process results to, for example, the output unit 307.

The storage unit 308 connected to the input / output interface 305 is composed of, for example, a hard disk or the like, and stores a program executed by the CPU 301 and various data. The communication unit 309 functions as a transmission / reception unit for data communication via a network such as the Internet or a local area network, and communicates with an external device.

The drive 310 connected to the input / output interface 305 drives a removable medium 311 such as a magnetic disk, an optical disk, a magneto-optical disk, or a semiconductor memory such as a memory card, and records or reads data.

The light projecting unit 321 corresponds to the light projecting unit 110 of the object detection device shown in FIGS. 3 and 20, and projects a plurality of types of polarized light.
The light receiving unit 322 corresponds to the light receiving unit 120 of the object detection device shown in FIGS. 3 and 20, and receives a plurality of types of polarized light as observation light.

[9. Summary of the structure of this disclosure]
As described above, the embodiments of the present disclosure have been described in detail with reference to the specific embodiments. However, it is self-evident that those skilled in the art may modify or substitute the examples without departing from the gist of the present disclosure. That is, the present invention has been disclosed in the form of an example and should not be construed in a limited manner. In order to judge the gist of this disclosure, the column of claims should be taken into consideration.

The technology disclosed in the present specification can have the following configurations.
(1) A light projecting unit that outputs at least three types of polarization in different polarization directions, and
A light receiving unit that receives the output light of the light projecting unit at at least three different observation polarization angles.
It has a data processing unit that determines whether or not a transparent object exists in the optical path from the light emitting unit to the light receiving unit based on the light receiving signal of the light receiving unit.
The data processing unit
Stress calculation to calculate the residual stress of the transparent object by using the light receiving signals of a plurality of different observation polarization angles received by the light receiving unit when the object presence / absence determination unit determines that a transparent object exists in the optical path. An object detection device having a part.

(2) The data processing unit is
A light receiving signal recording unit that stores light receiving signals having a plurality of different observation polarization angles received by the light receiving unit in a state where no transparent object exists in the optical path, and a light receiving signal recording unit.
It has a light receiving signal having a plurality of different observation polarization angles received by the light receiving unit, and an object presence / absence determining unit that determines the presence / absence of a transparent object in the optical path based on the light receiving signal recorded in the light receiving signal recording unit. The object detection device according to 1).

(3) The optical path from the light projecting section to the light receiving section is a linear optical path.
The object detection device according to (1) or (2), wherein the detection region for detecting the presence or absence of a transparent object is set in a linear optical path between the light emitting unit and the light receiving unit.

(4) The optical path from the light projecting section to the light receiving section is an optical path whose direction changes depending on the reflector.
The object detection device according to (1) or (2), wherein the detection region for detecting the presence or absence of a transparent object is set in an optical path whose direction is changed by the reflector.

(5) The light projecting unit has a configuration in which at least three or more types of polarizations in different polarization directions are output in parallel.
The object detection device according to any one of (1) to (4), wherein the light receiving unit has a configuration in which at least three or more types of polarizations in different polarization directions are input in parallel.

(6) The light projecting unit has a configuration in which at least three or more types of polarization in different polarization directions are sequentially output.
The object detection device according to any one of (1) to (4), wherein the light receiving unit sequentially inputs polarizations of at least three types in different polarization directions.

(7) The light projecting unit is configured to output four types of polarization having polarization directions of 0 °, 45 °, 90 °, and 135 °.
The object detection device according to any one of (1) to (6), wherein the light receiving unit is configured to input four types of polarization having polarization directions of 0 °, 45 °, 90 °, and 135 °.

(8) The light projecting unit is configured to output three types of polarization having polarization directions of 0 °, 45 °, and 90 °.
The object detection device according to any one of (1) to (6), wherein the light receiving unit has a configuration in which three types of polarization having a polarization direction of 0 °, 45 °, and 90 ° are input.

(9) The light projecting unit has a configuration in which at least three or more types of polarization in different polarization directions having a plurality of different wavelengths are output.
The object detection device according to any one of (1) to (8), wherein the light receiving unit is configured to input polarization of at least three types of different polarization directions having a plurality of different wavelengths.

(10) The received light signal recording unit is
At least three types of reference values, which are light receiving signals having at least three different observation polarization angles received by the light receiving unit in the absence of a transparent object in the optical path, are stored in the storage unit.
The object presence / absence determination unit is
The difference between the light-receiving signals having at least three different observation polarization angles received by the light-receiving unit and the reference value of the same observation polarization angle as the light-receiving signal is calculated.
The object detection device according to any one of (1) to (9), wherein it is determined that a transparent object exists in the optical path when at least one of the calculated differences of 3 or more is larger than a predetermined threshold value.

(11) The received light signal recording unit is
At least three types of reference values, which are light receiving signals having at least three different observation polarization angles received by the light receiving unit in the absence of a transparent object in the optical path, are stored in the storage unit.
The object presence / absence determination unit is
The added value of the difference between the light receiving signal having at least three different observation polarization angles received by the light receiving unit and the reference value having the same observation polarization angle as the light receiving signal is calculated.
The object detection device according to any one of (1) to (9), wherein it is determined that a transparent object exists in the optical path when the calculated difference addition value is larger than a predetermined threshold value.

(12) The stress calculation unit is
The object detection device according to any one of (1) to (11), wherein the residual stress and the stress direction of the transparent object are calculated by using the light receiving signals having at least three different observation polarization angles received by the light receiving unit.

(13) The object detection device further
It has a stress determination unit that compares the calculated data of the stress calculation unit with a predetermined threshold value and determines whether or not the residual stress of the transparent object is the residual stress that should be determined as a defective product (1). )-(11) The object detection device according to any one of (11).

(14) This is an object detection method executed by an object detection device.
The object detection device is
A floodlight that outputs at least three types of polarization in different polarization directions, and
A light receiving unit that receives the output light of the light projecting unit at at least three different observation polarization angles.
It has a data processing unit that determines whether or not a transparent object exists in the optical path from the light emitting unit to the light receiving unit based on the light receiving signal of the light receiving unit.
The data processing unit
Object detection that executes a stress calculation step to calculate the residual stress of the transparent object by using the light receiving signals of a plurality of different observation polarization angles received by the light receiving unit when it is determined that the transparent object exists in the optical path. Method.

(15) A program that executes an object detection process in an object detection device.
The object detection device is
A floodlight unit that outputs at least three types of polarization in different polarization directions, and
A light receiving unit that receives the output light of the light projecting unit at at least three different observation polarization angles.
It has a data processing unit that determines whether or not a transparent object exists in the optical path from the light emitting unit to the light receiving unit based on the light receiving signal of the light receiving unit.
The program is installed in the data processing unit.
A program for executing a stress calculation step of calculating the residual stress of the transparent object by using the light receiving signals having a plurality of different observation polarization angles received by the light receiving unit when it is determined that the transparent object exists in the optical path.

Further, the series of processes described in the specification can be executed by hardware, software, or a composite configuration of both. When executing processing by software, install the program that records the processing sequence in the memory in the computer built in the dedicated hardware and execute it, or execute the program on a general-purpose computer that can execute various processing. It can be installed and run. For example, the program can be pre-recorded on a recording medium. In addition to installing the program on a computer from a recording medium, the program can be received via a network such as a LAN (Local Area Network) or the Internet and installed on a recording medium such as a built-in hard disk.

It should be noted that the various processes described in the specification are not only executed in chronological order according to the description, but may also be executed in parallel or individually as required by the processing capacity of the device that executes the processes. Further, in the present specification, the system is a logical set configuration of a plurality of devices, and the devices of each configuration are not limited to those in the same housing.

As described above, according to the configuration of one embodiment of the present disclosure, a device and a method for detecting a transparent object and calculating the residual stress of the transparent object using polarization are realized.
Specifically, for example, it has a light projecting unit that outputs at least three types of different polarizations, a light receiving unit that receives light at at least three types of observation polarization angles, and a data processing unit. The data processing unit stores the light-receiving signal of the light-receiving part in a state where no transparent object exists in the optical path as a reference value, and stores the light-receiving signals of a plurality of different observation polarization angles received by the light-receiving part and the reference value. The presence or absence of a transparent object in the optical path is determined by comparison. Further, when it is determined that a transparent object exists in the optical path, the residual stress of the transparent object is calculated by using the light receiving signals having a plurality of different observation polarization angles received by the light receiving unit.
With this configuration, a device and a method for detecting a transparent object and calculating the residual stress of the transparent object using polarization are realized.

10 Floodlight 11 Polarizing plate 20 Light receiving unit 21 Polarizing plate 30 Space 50 Transparent object 100 Object detection device 101 Input unit 102 Control unit 103 Storage unit 104 Output unit 110 Light emitting unit 111 Light output unit 112 Polarization generation unit 120 Light receiving unit 121 Polarizing plate 122 Light receiving sensor 130 Data processing unit 131 Light receiving signal recording unit 132 Object presence / absence judgment unit 133 Stress calculation unit 134 Stress judgment unit 150 Detection area 170 Transparent object 180 Reflector 301 CPU
302 ROM
303 RAM
304 Bus 305 Input / output interface 306 Input unit 307 Output unit 308 Storage unit 309 Communication unit 310 Drive 311 Removable media 321 Floodlight unit 322 Light receiving unit

Claims (12)

A floodlight that outputs at least three types of polarization in different polarization directions, and
A light receiving unit that receives the output light of the light projecting unit at at least three different observation polarization angles.
It has a data processing unit that determines whether or not a transparent object exists in the optical path from the light emitting unit to the light receiving unit based on the light receiving signal of the light receiving unit.
The data processing unit
A light receiving signal recording unit that stores at least three types of reference values, which are light receiving signals having at least three different observation polarization angles received by the light receiving unit in the absence of a transparent object in the optical path, and a light receiving signal recording unit.
The difference between the light-receiving signals having at least three different observation polarization angles received by the light-receiving unit and the reference value of the same observation polarization angle as the light-receiving signal is calculated.
If at least one of the calculated differences of 3 or more is greater than the predetermined threshold, or
An object presence / absence determination unit that determines that a transparent object exists in the optical path when the added value of the calculated difference of 3 or more is larger than the predetermined threshold value.
Stress calculation to calculate the residual stress of the transparent object by using the light receiving signals of a plurality of different observation polarization angles received by the light receiving unit when the object presence / absence determination unit determines that a transparent object exists in the optical path. An object detection device having a part. The optical path from the light projecting section to the light receiving section is a linear optical path.
The object detection device according to claim 1, wherein the detection region for detecting the presence or absence of a transparent object is set in a linear optical path between the light emitting unit and the light receiving unit. The optical path from the light projecting section to the light receiving section is an optical path whose direction changes depending on the reflector.
The object detection device according to claim 1, wherein the detection region for detecting the presence or absence of a transparent object is set in an optical path whose direction is changed by the reflector. The light projecting unit has a configuration in which at least three or more types of polarizations in different polarization directions are output in parallel.
The object detection device according to claim 1, wherein the light receiving unit has a configuration in which at least three or more types of polarizations in different polarization directions are input in parallel. The light projecting unit has a configuration in which at least three or more types of polarizations in different polarization directions are sequentially output.
The object detection device according to claim 1, wherein the light receiving unit sequentially inputs polarizations of at least three types in different polarization directions. The light projecting unit is configured to output four types of polarization having polarization directions of 0 °, 45 °, 90 °, and 135 °.
The object detection device according to claim 1, wherein the light receiving unit is configured to input four types of polarization having polarization directions of 0 °, 45 °, 90 °, and 135 °. The light projecting unit is configured to output three types of polarization having polarization directions of 0 °, 45 °, and 90 °.
The object detection device according to claim 1, wherein the light receiving unit has a configuration in which three types of polarization having a polarization direction of 0 °, 45 °, and 90 ° are input. The light projecting unit has a configuration in which at least three or more types of polarization in different polarization directions having a plurality of different wavelengths are output.
The object detection device according to claim 1, wherein the light receiving unit is configured to input polarization in at least three types of different polarization directions having a plurality of different wavelengths. The stress calculation unit
The object detection device according to claim 1, wherein the residual stress and the stress direction of the transparent object are calculated by using the light receiving signals having at least three different observation polarization angles received by the light receiving unit. The object detection device further
A claim having a stress determination unit that compares the calculated data of the stress calculation unit with a predetermined threshold value and determines whether or not the residual stress of the transparent object is the residual stress that should be determined as a defective product. The object detection device according to 1. It is an object detection method executed by an object detection device.
The object detection device is
A floodlight that outputs at least three types of polarization in different polarization directions, and
A light receiving unit that receives the output light of the light projecting unit at at least three different observation polarization angles.
It has a data processing unit that determines whether or not a transparent object exists in the optical path from the light emitting unit to the light receiving unit based on the light receiving signal of the light receiving unit.
The data processing unit
A light-receiving signal recording step for storing at least three types of reference values, which are light-receiving signals having at least three different observation polarization angles received by the light-receiving unit in the absence of a transparent object in the optical path, and a storage unit.
The difference between the light-receiving signals having at least three different observation polarization angles received by the light-receiving unit and the reference value of the same observation polarization angle as the light-receiving signal is calculated.
If at least one of the calculated differences of 3 or more is greater than the predetermined threshold, or
An object presence / absence determination step for determining that a transparent object exists in the optical path when the added value of the calculated difference of 3 or more is larger than a predetermined threshold value.
When it is determined in the object presence / absence determination step that a transparent object exists in the optical path, the stress calculation for calculating the residual stress of the transparent object by using the light receiving signals of a plurality of different observation polarization angles received by the light receiving unit. An object detection method that performs a step. It is a program that executes the object detection process in the object detection device.
The object detection device is
A floodlight that outputs at least three types of polarization in different polarization directions, and
A light receiving unit that receives the output light of the light projecting unit at at least three different observation polarization angles.
It has a data processing unit that determines whether or not a transparent object exists in the optical path from the light emitting unit to the light receiving unit based on the light receiving signal of the light receiving unit.
The program is installed in the data processing unit.
A light-receiving signal recording step for storing at least three types of reference values, which are light-receiving signals having at least three different observation polarization angles received by the light-receiving unit in the absence of a transparent object in the optical path, and a storage unit.
The difference between the light-receiving signals having at least three different observation polarization angles received by the light-receiving unit and the reference value of the same observation polarization angle as the light-receiving signal is calculated.
If at least one of the calculated differences of 3 or more is greater than the predetermined threshold, or
An object presence / absence determination step for determining that a transparent object exists in the optical path when the added value of the calculated difference of 3 or more is larger than a predetermined threshold value.
Stress calculation for calculating the residual stress of the transparent object by using the light receiving signals of a plurality of different observation polarization angles received by the light receiving unit when it is determined in the object presence / absence determination step that a transparent object exists in the optical path. A program that executes a step.

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