JPWO2018216349A1 - Object detection device, object detection method, and program - Google Patents

Abstract

Provided are an apparatus and a method for detecting a transparent object and calculating residual stress of the transparent object using polarized light. It has a light projecting unit that outputs at least three or more different polarizations, a light receiving unit that receives at least three or more different observation polarization angles, and a data processing unit. The data processing unit stores the received light signal of the light receiving unit in a state where no transparent object is present in the optical path in the storage unit as a reference value, and stores the received light signals of the plurality of different observation polarization angles received by the light receiving unit 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 of the plurality of different observation polarization angles received by the light receiving unit.

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, an object detection method, and a program that execute processing for detecting a transparent object, detecting stress in the object, and the like.

As a process for detecting the presence or absence of an object, there is a process using a photoelectric sensor.
For example, in a setting where an object to be detected passes irregularly on a belt conveyor on a production line of a factory, light is emitted onto the belt conveyor, and the reflected light is received by a 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 reflecting plate or the belt conveyor surface,
(B) When an object is present on the belt conveyor and the photoelectric sensor receives reflected light of the object,
Causes a difference. An object can be detected based on this difference.

However, when the object to be detected is a transparent object with high light transmittance, the reflected light received by the photoelectric sensor is almost the same in both cases when the object to be detected exists and when it does not exist. And no large difference occurs.
For this reason, there is a problem that the detection capability of the object is reduced.

  As a configuration for improving the detection accuracy of a transparent object having a high light transmittance, there is a configuration using polarized light. Utilizing the property that when a linearly polarized light is transmitted through a transparent material, it is converted into elliptically polarized light. A linear polarization filter (polarizing plate) is arranged in the light emitting part and the light receiving part, and the linearly polarized light is transmitted through the transparent material. In this method, the transmitted light is received by a sensor, the amount of attenuation of the received light amount is increased, and the detection accuracy is improved.

For example, Patent Literature 1 (Japanese Patent Application Laid-Open No. H10-111365) discloses that 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 projecting unit and the light receiving unit. The configuration is disclosed.
When there is no transparent object at the object detection position, the linearly polarized light emitted from the light projecting unit is received by the light receiving unit on which the linearly polarizing plate is disposed as it is. On the other hand, when a transparent object is present at the object detection position, the linearly polarized light emitted from the light projecting unit passes through the transparent object and is converted into elliptically polarized light. Received.
With such a configuration, the amount of light received by the light receiving unit can be greatly varied depending on the presence or absence of the transparent object, and highly accurate detection of the transparent object is realized.

Japanese Patent Application Laid-Open No. 7-294663 also discloses that a light projecting unit and a light receiving unit are disposed so as to sandwich an object detection position, and a one-way linear polarizing plate is provided in the light projecting unit. And a configuration in which two-way polarizing plates are disposed in the light receiving unit.
According to this configuration, even when the direction of the surface of the detection target changes and the amount of polarized light received in one direction does not attenuate, the attenuation of the amount of light in the remaining one direction can be observed, and the transparent object can be more stably than the Patent Document 1. A configuration that allows detection is disclosed.

Further, Patent Document 3 (Japanese Patent Application Laid-Open No. 2010-107475) discloses 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. Has been disclosed.
The light projecting unit has a linear polarizing plate in one direction, and the three light receiving units have polarizing plates having different directions.
By analyzing changes in the amounts 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 production line of a factory, in addition to the above-described object detection, for example, measurement of residual stress is often performed as a quality inspection such as 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 process such as removing a resin molded product having a residual stress larger than a reference value from the manufacturing process as a defective product is performed.

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

JP-A-10-11365 JP-A-7-294663 JP 2010-107475 A

As described above, various proposals have been made for a configuration for detecting a transparent object by using a polarizing filter (polarizing plate).
When one piece of linearly polarized light is observed through a polarizing plate in a plurality of directions, it changes sinusoidally according to the polarization direction used for observation. Basically, this change in the sine function can be restored by observing in three different polarization directions.
That is, when observed in three directions, even in a transparent object, 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 Literature 1 and Patent Literature 2 described above can only observe light amounts in a maximum of two polarization directions. Therefore, there is a problem that the amount of light required for detection does not attenuate depending on the shape and orientation of the detection target, and stable detection cannot be performed.
Specifically, for example, if the direction of a transparent flat plate is changed, there is a high possibility that detection cannot be performed.

Further, the configuration described in Patent Literature 3 solves the above-described problem by observing polarized lights having three different directions in three light receiving units.
However, the configuration described in Patent Literature 3 is a configuration in which irradiation light from one light projecting unit is received by light receiving units at three spatially separated positions, so that each of the three light receiving units receives light. The transmitted light is not transmitted light at the same point of the detection target, but is transmitted light at a different position.
Therefore, when the detection target is small or the like, each of the three light receiving units cannot receive the transmitted light of the detection target at the same time, and the detection accuracy is reduced.

  The present disclosure has been made in view of, for example, the above-described problems, and has an object detection device capable of performing highly accurate object detection processing when an object to be detected is an object having high light transmittance, and an object. It is an object to provide a detection method and a program.

  In addition, according to an embodiment of the present disclosure, an object detection device, an object detection method, and a program that enable detection of stress in an object in addition to detection of the object are provided.

A first aspect of the present disclosure is:
A light emitting unit that outputs polarized light of at least three or more different polarization directions,
A light receiving unit that receives output light of the light emitting unit at at least three or more different observation polarization angles,
Based on a light receiving signal of the light receiving unit, a data processing unit that determines whether a transparent object is present in an optical path from the light emitting unit to the light receiving unit,
The data processing unit includes:
An object detection device including a stress calculation unit configured to calculate a residual stress of the transparent object using light reception signals of a plurality of different observation polarization angles received by the light reception unit when it is determined that a transparent object exists in the optical path; It is in.

Further, a second aspect of the present disclosure includes:
An object detection method executed by the object detection device,
The object detection device,
A light emitting unit that outputs polarized light of at least three or more different polarization directions,
A light receiving unit that receives output light of the light emitting unit at at least three or more different observation polarization angles,
Based on a light receiving signal of the light receiving unit, a data processing unit that determines whether a transparent object is present in an optical path from the light emitting unit to the light receiving unit,
The data processing unit includes:
When it is determined that a transparent object is present in the optical path, an object detection is performed by performing a stress calculation step of calculating a residual stress of the transparent object using light reception signals of a plurality of different observation polarization angles received by the light receiving unit. In the way.

Further, a third aspect of the present disclosure includes:
A program for executing an object detection process in the object detection device,
The object detection device,
A light emitting unit that outputs polarized light of at least three or more different polarization directions,
A light receiving unit that receives output light of the light emitting unit at at least three or more different observation polarization angles,
Based on a light receiving signal of the light receiving unit, a data processing unit that determines whether a transparent object is present in an optical path from the light emitting unit to the light receiving unit,
The program, the data processing unit,
When it is determined that a transparent object is present in the optical path, a program that executes a stress calculation step of calculating a residual stress of the transparent object using light reception signals of a plurality of different observation polarization angles received by the light receiving unit. is there.

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

  Further objects, features, and advantages of the present disclosure will become apparent from the following detailed description based on embodiments of the present invention and the accompanying drawings. In this specification, a system is a logical set configuration of a plurality of devices, and is not limited to a configuration in which devices of each configuration are in the same housing.

According to the configuration of an embodiment of the present disclosure, an apparatus and a method for detecting a transparent object and calculating residual stress of the transparent object using polarized light are realized.
Specifically, for example, it has a light projecting unit that outputs at least three or more different polarizations, a light receiving unit that receives at least three or more different observation polarization angles, and a data processing unit. The data processing unit stores the received light signal of the light receiving unit in a state where no transparent object exists in the optical path in the storage unit as a reference value, and stores the received light signal of the plurality of different observation polarization angles received by the light receiving unit 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 of the plurality of different observation polarization angles received by the light receiving unit.
With this configuration, an apparatus and a method for detecting a transparent object and calculating the residual stress of the transparent object using polarized light are realized.
It should be noted that the effects described in the present specification are merely examples and are not limited, and may have additional effects.

FIG. 9 is a diagram illustrating a configuration example of a transparent object detection process using polarized light. It is a figure which shows the optical characteristic of linearly polarized light and elliptically polarized light. FIG. 2 is a block diagram illustrating a configuration example of an object detection device. It is a figure showing an example of 1 composition of a light projection part. It is a figure showing an example of 1 composition of a light sensing portion. It is a figure explaining an example of reference value acquisition processing. It is a figure explaining an example of a transparent object existence detection processing. It is a figure showing an example of 1 composition of a light projection part. It is a figure showing an example of 1 composition of a light sensing portion. It is a figure showing an example of 1 composition of a light projection part. It is a figure showing an example of 1 composition of a light sensing portion. It is a figure showing an example of 1 composition of a light projection part. It is a figure showing an example of 1 composition of a light sensing portion. It is a figure explaining an example of reference value acquisition processing. It is a figure explaining an example of a transparent object existence detection processing. It is a figure showing an example of 1 composition of a light projection part. It is a figure showing an example of 1 composition of a light sensing portion. It is a figure showing an example of 1 composition of a light projection part. It is a figure showing an example of 1 composition of a light sensing portion. FIG. 2 is a block diagram illustrating a configuration example of an object detection device. It is a figure showing an example of 1 composition of a light projection part and a light sensing portion. FIG. 9 is a flowchart illustrating a processing sequence executed by the object detection device according to the present disclosure. FIG. 9 is a flowchart illustrating a processing sequence executed by the object detection device according to the present disclosure. FIG. 9 is a flowchart illustrating a processing sequence executed by the object detection device according to the present disclosure. FIG. 3 is a diagram illustrating a hardware configuration example of an object detection device.

Hereinafter, details of an object detection device, an object detection method, and a program of the present disclosure will be described with reference to the drawings. The description will be made in accordance with the following items.
1. 1. Processing for detecting a transparent object using polarized light 2. Stress detection processing using polarized light (Embodiment 1) Embodiment 1 of an object detection device for detecting a transparent object using polarized light and calculating residual stress
4. (Embodiment 2) Embodiment 2 of an object detection apparatus for detecting a transparent object using polarized light and calculating residual stress
5. (Embodiment 3) Embodiment 3 of an object detection apparatus for detecting a transparent object using polarized light and calculating residual stress
6. 6. Other embodiments 7. Sequence of processing executed by object detection apparatus 8. Example of hardware configuration of object detection device Summary of configuration of the present disclosure

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

The light emitted from the light projecting unit 10 via the polarizing plate 11 passes through the transparent object 50 when the transparent object 50 exists, 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 via the polarizing plate 11 is received by the light receiving unit 20 having the polarizing plate 21 as it is.

Light emitted from the light projecting unit 10 via the polarizing plate 11 is linearly polarized light.
When the transparent object 50 does not exist, the light receiving unit 20 receives this linearly polarized light.
On the other hand, the transparent object 50 exists, and the light that has passed 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.
The outline of the characteristics of linearly polarized light and elliptically polarized light and the principle of change from linearly polarized light to elliptically polarized light by a transparent object will be described below.

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 vibrate orthogonally to the traveling direction.
Here, the light component whose electric field vibrates in the vertical direction is called P-polarized light, and the light component whose electric field vibrates horizontally is called S-polarized light.
The linearly polarized light is a polarized light having no phase difference between the P-polarized light and the S-polarized light, 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 illustrating optical characteristics of linearly polarized light.
FIG. 2 (a1) is a diagram showing the amplitude characteristic of linearly polarized light. FIG. Is shown.
As described above, the linearly polarized light has no phase difference between the P-polarized light and the S-polarized light, and has a polarization direction limited to one plane. (= The trajectory of the tip of the electric field vector) is a straight line as shown in FIG.
FIG. 2 (a2) 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 linearly polarized light and the observed intensity (relative value) is a graph of a trigonometric function as shown in FIG.

As shown in FIG. 1, the linearly polarized light output from the light projecting unit 10 travels in the space (refractive index N ₁ ) 30 along the Z axis and has a transparent object (refractive index) having a different refractive index from the space 30. Rate N ₂ ) 50 and passes through the transparent object 50. Light passing through the transparent object 50 is received by the light receiving unit 20 having the polarizing plate 21.

When linearly polarized light enters the transparent object (refractive index N ₂ ) 50 having a different refractive index from the space 30 (refractive index N ₁ ) 30 and passes through the transparent object 50, the linearly polarized light is converted into elliptically polarized light. 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 (CD will be briefly described.
Linearly polarized light can be regarded as the sum of left circularly polarized light and right circularly polarized light. That is, the left circularly polarized light and the right circularly polarized light pass through the transparent object.
However, many transparent objects have different absorbances for left circularly polarized light and right circularly polarized light.
Such a phenomenon that a difference occurs in the absorbance between left circularly polarized light and right circularly polarized light is called circular dichroism (CD).

  The linearly polarized light, which is the balanced sum of the left circularly polarized light and the right circularly polarized light, passes through the transparent object 50 having circular dichroism (CD), so that the balance between the left circularly polarized light and the right circularly polarized light is lost. It changes from polarized light to elliptically polarized light.

The elliptically polarized light is a polarized light in which a phase difference between the P-polarized light and the S-polarized light is generated. The elliptically polarized light is a polarized light whose polarization direction is not one plane. The direction (= trajectory of the tip of the electric field vector) becomes an ellipse as shown in FIG. 2 (b1).
FIG. 2 (b2) 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 a trigonometric function as shown in FIG. 2 (b2).

As described above, the light emitted from the light projecting unit 10 via 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, and the light that has passed 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 linearly polarized P-polarized light and S-polarized light is zero.
On the other hand, the phase difference between the elliptically polarized P-polarized light and the S-polarized light that has passed through the transparent object 50 is not 0, and the phase difference φ is as shown in the following (Equation 1).

In the above (Equation 1), λ is the wavelength of light, N ₁ is the refractive index of the 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 it.

Further, at a point Z of elliptically polarized light that has passed through the transparent object 50,
Vibration in X direction (vibration of S polarized light) = Ax (Z),
Vibration in the Y direction (P-polarized vibration) = 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 in the X direction of the elliptically polarized light that is the outgoing light (passing light) of the transparent object 50;
A _1Y is the amplitude in the Y direction of the elliptically polarized light that is the light (passing light) emitted from the transparent object 50;
It is.

Further, the intensity (luminance) of the observation 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 observation 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 is present, the linearly polarized light 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 the following (Equation 4) and (Equation 5), the observation luminance I (θ) corresponding 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 calculated.

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

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

The above (Equation 5) corresponds to the graph of (b2) polarization angle-intensity characteristics of the elliptically polarized light shown in FIG.
The observation luminance I (θ) calculated by (Equation 5) corresponds to the observation intensity in the (b2) polarization angle-intensity graph of the elliptically polarized light shown in FIG.
The observation polarization angle (θ) shown in (Equation 5) corresponds to the observation polarization angle (θ) on the horizontal axis in FIG.
That is, the correspondence between the observed polarization angle (θ) of elliptically polarized light and the observed luminance (I (θ)) represented by the relational expression of (Equation 5) is a graph of a trigonometric function shown in FIG. 2B2.

If the correspondence between the observed polarization angle (θ) and the observed luminance I (θ) obtained based on this observed value corresponds to the triangular function graph of linearly polarized light shown in FIG. The emitted light is linearly polarized light, 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) and the observed luminance I (θ) obtained based on the observed value corresponds to the elliptically polarized light trigonometric function graph shown in FIG. The received light is elliptically polarized light, and it can be determined that the transparent object 50 exists.

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

The unknown included in the above (Equation 4) is
X-direction amplitude of linearly polarized light: _A0X ,
Amplitude of linearly polarized light in the Y direction: A _0Y ,
These two values.
On the other hand, the unknowns included in the above (Equation 5) are:
X-direction amplitude of elliptically polarized light: A _1X ,
Amplitude of elliptically polarized light in the Y direction: A _1Y ,
Phase difference: φ
These three values.

  Thus, when the light receiving unit 20 receives linearly polarized light according to the above (Equation 4), two unknowns are received, and when the light receiving unit 20 receives elliptically polarized light according to the above (Equation 5), There are three unknowns, and by acquiring the observation luminance I (θ) corresponding to at least three different observation polarization angles (θ), the triangular shape according to any of the above (Equation 4) and (Equation 5) is obtained. It can be determined whether an 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 observation luminance I (θ) at each observation polarization angle (θ) may be obtained as an observation value.

Thus, the light received by the light receiving unit 20 is
Linearly polarized light that does not pass through the transparent object 50,
Whether it is elliptically polarized light that has passed through the transparent object 50,
In order to determine, sampling of at least three points is required.

The device configuration for executing the transparent object detection processing and the processing sequence will be described later in detail.
In the object detection device according to the present disclosure described later, a detection process using different polarizations in three or more directions is performed, and it is possible to 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 with respect to the one linearly polarized light at a plurality of observation polarization angles. However, in the configuration of the present disclosure, a plurality of (three or more types) linearly polarized lights having different polarization angles are output in parallel or sequentially output in time series from the light projecting unit.

The light receiving unit receives a light receiving signal based on the plurality of linearly polarized lights, that is, elliptically polarized light that has passed through a transparent object or linearly polarized light that has not passed through.
The light receiving unit also observes the received light signal at a plurality of different observation polarization angles.
By performing such processing, the accuracy of detecting a transparent object is increased.
A specific transparent object presence / absence determination process will be described later in detail.

Transparent objects passing through the detection area may be set at various angles, and many transparent objects have individual differences, such as distortion based on internal materials and stress, etc., and are input to each transparent object. Linearly polarized light produces different behavior depending on the angle of the transparent object and the difference in the internal material.
Therefore, it can be assumed that a change from linearly polarized light to elliptically polarized light cannot be confirmed with only one linearly polarized light.

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

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

[2. Stress detection using polarized light]
As described above, for example, in a manufacturing line of a factory, for example, measurement of residual stress is often performed as a quality inspection of the strength of a molded product such as a resin in addition to the above-described object detection.
If the residual stress is large, there is a high possibility of causing deformation, cracking, and the like. For example, processing such as removing a resin molded product having a residual stress larger than a specified value from the manufacturing process as a defective product is performed.

As a conventional general method of measuring residual stress, an object is irradiated while rotating the illumination-side polarizing plate at a plurality of angles, and the transmitted light is passed through a polarizing plate having a polarization angle corresponding to each illumination-side polarization angle. There is a way to observe.
However, this method requires an accurate rotation control mechanism of the polarizing plate, control of measurement timing on each light receiving side, and the like, and thus requires a high-cost and complicated system. In addition, there is a problem in that real-time measurement is difficult because analysis processing of observation data requires time.
In the following, a description will be given of a residual stress measurement process that solves these problems.
The residual stress (N) of the residual stress measurement object can be calculated by the following (Equation 6).

In the above (Equation 6),
N is the residual stress,
α is the photoelastic constant specific to the material of the object to be measured,
d is the thickness of the material to be measured,
σ ₁ is the main stress representing the tensile component in the residual stress,
σ ₂ is a main stress representing a compressive component in the residual stress,

When the main stress σ ₁ representing the tensile component in the residual stress is large, the density of the material decreases, and the strength decreases. Further, when the main stress σ ₂ representing the compression component in the residual stress is large, the density of the material increases, and the strength increases.

Due to the distribution of the residual stress, strain occurs in the material density inside the material. When polarized light is allowed to pass through such a strained substance, there is a difference in the refractive index between the vertical direction and the horizontal direction, so that the polarization component changes.
By observing this change, the residual stress of the measurement object can be measured.
In this example, the measurement target is a transparent object that transmits light.

With reference to the configuration shown in FIG. 1, a process for measuring the residual stress of the transparent object 50 will be described.
The light projecting unit 10 irradiates, through the polarizing plate 11, polarized light of four types of angles (0 °, 45 °, 90 °, and 135 °) to the transparent object 50 that is a measurement object of the residual stress.

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

The four polarized lights that have passed through the transparent object 50 pass through the polarizing plate 21 having the same four types of angles (0 °, 45 °, 90 °, and 135 °) set in the light receiving unit 20, respectively. The light is received at.
The polarizing plate 21 on the side of the light receiving unit 20 may also be set to have four polarization angles (0 °, 45 °, 90 °, 135 °) as the divided regions, or
The polarizing plate 21 having one polarization direction may be sequentially changed in time series to four polarization angles (0 °, 45 °, 90 °, 135 °).

Observed luminances of polarized light at four types of angles (0 °, 45 °, 90 °, 135 °) received by the light receiving unit 20 are defined as I ₀ , I ₄₅ , I ₉₀ , and I ₁₃₅ .
Using the observation luminances corresponding to the four polarized lights, the equation for calculating the residual stress (N) shown in (Equation 6) can be rewritten as (Equation 7) below.

  The parameters shown in the above (Equation 7) are the settings shown in the following (Equation 8) to (Equation 10).

Note that _Ib is the brightness of the background and is a constant.

  The stress direction (φ) is represented by the following (Equation 11).

As described above, the residual stress in the transparent object 50 is obtained using the observation luminances (I ₀ , I ₄₅ , I ₉₀ , I ₁₃₅ ) of the polarized light at four angles (0 °, 45 °, 90 °, 135 °). And the stress direction can be calculated.

  In addition, in order to enhance the measurement stability of the residual stress, it is preferable to use four types of polarized light, but theoretically, the residual stress and the stress direction can be calculated even with three polarized light.

  As an example, a description will be given of an example of calculation processing of residual stress and stress direction using three polarized lights (0 °, 45 °, 90 °).

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

As described above, the residual stress and the stress direction in the transparent object 50 are calculated using the observation luminances (I ₀ , I ₄₅ , I ₉₀ ) of the polarized light at three angles (0 °, 45 °, 90 °). be able to.

  Hereinafter, a plurality of specific examples of a device and a processing sequence for detecting the presence or absence of a transparent object and detecting residual stress will be described.

[3. (Embodiment 1) Embodiment 1 of an object detection apparatus for detecting a transparent object using polarized light and calculating residual stress]
First, a first embodiment of an object detection device that performs transparent object detection using polarization and calculates residual stress will be described.

FIG. 3 is a block diagram illustrating a configuration example of the object detection device 100 according to the first embodiment.
As illustrated 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.

  Polarized light 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, and whether or not the transparent object 170 exists in the detection area 150 based on the received light signal The transparent object presence / absence determination is performed, and when the transparent object 170 is detected, the calculation of the residual stress of the transparent object is also performed.

The input unit 101 includes information serving as a trigger for processing control by the user such as start and stop of the object detection processing, and mode setting information such as a mode for only the object detection processing and a mode for performing the object detection and the stress detection. Is input.
In addition, it is also used for input of parameters necessary for processing, such as setting information of polarization to be used, and for input of thresholds and the like used for object detection, stress calculation processing, and the like.

The control unit 102 controls the processing of each component, controls the execution timing, and the like, and controls the processing of the entire object detection device 100.
Note that the control unit 102 includes, 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 a parameter, a reference value, a threshold value applied to data processing in the data processing unit 130, a program executed in the control unit 102, and the like.

The output unit 104 outputs, for example, a data processing result in the data processing unit 130.
Specifically, detection information on whether a transparent object has been detected, information on the residual stress calculated for the detected transparent object, and a non-defective / 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 generation unit 112.
The light projecting unit 110 has a configuration in which a plurality (three or more types) of linearly polarized lights having different polarization angles are output in parallel or sequentially output in time series.
A specific configuration example of the light projecting unit 110 will be described later in detail.

The light receiving section 120 has a polarizing plate 121 and a light receiving sensor 122.
The light receiving unit 120 differs between elliptically polarized light, which is light passing through the transparent object 170 based on a plurality (three or more types) of linearly polarized light output from the light projecting unit 110, or linearly polarized light, which is light not passing through the transparent object 170. It has a configuration for observation at the observation polarization angle.
The light receiving unit 120 also has a configuration in which a plurality of (three or more) different observation polarization angles (θ) are set, and the observation luminance I (θ) at each observation polarization angle (θ) is obtained 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 reception 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 outputs an input signal necessary to determine whether or not the transparent object 170 exists in the detection area 150. Perform analysis.

For example, the light reception signal recording unit 131 inputs a light reception signal of the light reception 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. , And the calculated reference value is stored in the storage unit 103.
This reference value is used in subsequent actual transparent object presence / absence determination processing to determine the presence / absence of a transparent object.
After this reference value acquisition processing, the actual transparent object detection processing is started.

  In the transparent object detection process, when the transparent object 170 exists in the detection area 150, 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, a 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 reception signal recording unit 131 with a reference value stored in the storage unit to determine 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 a 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 a predetermined threshold, it is determined that the transparent object 170 does not exist in the detection area 150.

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

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, the transparent object presence / absence determination processing is executed using all of the polarizations having different polarization angles output by the light projecting unit 110. This processing reduces the occurrence of the problem that the detection accuracy is reduced in accordance with, for example, the direction of the transparent object.

The stress calculation unit 133 determines the residual stress in the transparent object 170 in the detection area 150 and the residual stress in the detection area 150 when the determination result of the object presence / absence determination unit 132 indicates that the transparent object 170 is present in the detection area 150. Calculate the direction.
This stress calculation is based on the item [2. Regarding Stress Detection Processing Using Polarized Light].
That is, the residual stress inside the transparent object 170 and its direction are calculated using a plurality of (three or more) 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 defective or non-defective 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 is performed. The residual stress inside the transparent object 170 calculated by the stress calculation unit 133 and its direction are compared with a threshold value to determine 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 (three or more types) of linearly polarized lights having different polarization angles are output in parallel or sequentially output in time series.
The light receiving unit 120 also has a configuration in which a plurality of (three or more) different observation polarization angles (θ) are set, and the observation luminance I (θ) at each observation polarization angle (θ) is obtained as an observation value.

As described above, the transparent object 170 passing through the detection area 150 may be set at various angles, and a large number of transparent objects have individual differences such as distortion due to internal materials and stress. . The linearly polarized light input to each transparent object generates different behavior depending on the angle of the transparent object and the difference in the internal material.
Therefore, it can be assumed that a change from linearly polarized light to elliptically polarized light cannot be confirmed with only one linearly polarized light.

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

Hereinafter, a plurality of configuration examples of the light projecting unit 110 and the light receiving unit 120 will be described in detail.
FIG. 4 is a diagram illustrating 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 generation unit 112.
FIG. 4A shows a specific configuration example of the polarization generation unit 112.
As shown in FIG. 4A, the polarization generation unit 112 of the light projection unit 110 is configured by a combination of four types of polarizing plates having four types of polarization directions (polarization angles).

More specifically, (0 °, 45 °, 90 °, 135 °) is a configuration in which polarizing plates having these four types of polarization directions are combined.
FIG. 4B shows the polarization directions (polarization angles) of the four polarizing plates 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 (a to d) polarization directions are combined.
With this configuration, the light projecting unit 110 outputs linearly polarized lights 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 the linearly polarized light having a plurality of different polarization angles output from the light projecting unit 110 via a transparent object or as it is.

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

More specifically, (0 °, 45 °, 90 °, 135 °) is a configuration in which polarizing plates having these four types of polarization directions are combined.
FIG. 5B shows the polarization directions (polarization angles) of the four polarizing plates 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 (a to d) polarization directions are combined.

An optical signal passing through a polarizing plate 121 obtained by combining polarizing plates having the above four (a to d) polarization directions is input to a light receiving sensor 122, and is converted into an electric signal corresponding to the amount of optical signal (light intensity). The 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 observation luminance I (θ) at four different observation polarization angles (θ) is obtained as the observation value.

Observation luminance I (θ), which is an observation value at four different observation 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 becomes transparent in the detection area 150. It is used to determine whether the object 170 exists.
Further, when it is determined that the transparent object 170 is present in the detection area 150, it is also used for calculating the residual stress inside the transparent object 170.

Processing to be executed using the light projecting unit 110 and the light receiving unit 120 described with reference to FIGS. 4 and 5, that is, specific determination processing of whether or not the transparent object 170 exists in the detection area 150 This will be described with reference to FIGS.
As described above, the light reception signal recording unit 131 inputs the light reception signal of the light reception unit 120 in a state where the transparent object 170 does not exist in the detection region 150 as a preliminary preparation process, 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 the reference value acquisition processing, the actual detection processing is started.

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

The user confirms that the transparent object 170 does not exist in the detection area 150, inputs a processing start request (trigger signal) from the input unit 101 in this state, and starts the analysis of the received light signal.
The light receiving unit 120 receives the signals of the four different observation polarization angles described with reference to FIG. 5, and the received light signals are input to the received light signal recording unit 131.
The light receiving signal of the light receiving unit 120 is the following signal.
Ia_o = Received signal at 0 ° observed polarization angle without transparent object Ib_o = Received signal at 45 ° observed polarization angle without transparent object Ic_o = Received light at 90 ° observed polarization angle without transparent object Signal Id_o = received signal at observation polarization angle of 135 ° in the absence of a transparent object The optical signal analyzer 131 stores these four signals (Ia_o, Ib_o, Ic_o, Id_o) in the storage unit 103 as reference values (reference signal values). Store.

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

The details of the transparent object detection processing will be described with reference to FIG.
In the transparent object detection process, when the transparent object 170 exists in the detection area 150, 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, a 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 reception signal recording unit 131 with a reference value stored in the storage unit to determine 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 = Received signal at observation polarization angle of 0 ° Ib = Received signal at observation polarization angle of 45 ° Ic = Received signal at observation polarization angle of 90 ° Id = Received signal at observation polarization angle of 135 °

  The object presence / absence determining 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. Determine whether or not.

Specifically, for example, a determination process according to the following determination formula is executed.
Light receiving signal values (Ia, Ib, Ic, Id) through the four polarizing plates (a to d);
By calculating the difference from the reference value (Ia_o, Ib_o, Ic_o, Id_o),
The difference value is compared with a threshold value. 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 expressions 11a to 11d),
Th1a to Th1d are predetermined threshold values.
This threshold value is stored in the storage unit 103.
The above-mentioned judgment formulas 11a to 11d are judgment formulas for comparing the difference between the acquired signal value and the reference value at each observation polarization angle with a prescribed threshold value (Th1a to Th1d).

When any one of the above (judgment formulas 11a to 11d) is satisfied, that is,
If at least one of the difference between the acquired signal value and the reference value at each observation polarization angle is larger than a predetermined threshold value, it is determined that the transparent object 170 exists in the detection area 150.
On the other hand, when all of the above (judgment formulas 11a to 11d) do not hold, that is,
If none of the difference between the obtained signal value and the reference value at each observation polarization angle is larger than a predetermined threshold value, it is determined that the transparent object 170 does not exist in the detection area 150.

Note that a process using only one determination formula (determination formula 12) as follows, instead of the above four determination formulas, may be executed.
(Ia-Ia_o) + (Ib-Ib_o) + (Ic-Ic_o) + (Id-Id_o)> Th1 (judgment formula 12)

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

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

As described above, in the configuration of the present disclosure, the transparent object presence / absence determination process uses all of the polarizations having different polarization angles output by the light projecting unit 110. This processing reduces the occurrence of the problem that the detection accuracy is reduced in accordance with, for example, the direction of the transparent object.
Note that 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 process of calculating the residual stress and its direction is performed according to the item [2. Regarding Stress Detection Processing Using Polarized Light].

The stress determination unit 134 performs a determination process of determining whether the transparent object 170 is defective or non-defective 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 is performed. The residual stress inside the transparent object 170 calculated by the stress calculation unit 133 and its direction are compared with a threshold value to determine whether the transparent object 170 is a good product or a defective product.
The determination result is output to the output unit 104.

The configurations of the light projecting unit 110 and the light receiving unit 120 are not limited to the configurations described with reference to FIGS. 4 and 5, and various other configurations are possible.
Other configuration examples of the light projecting unit 110 and the light receiving unit 120 will be described with reference to FIG.

FIG. 8 is a diagram illustrating a configuration example of the light projecting unit 110.
As described above with reference to FIG. 4, the polarization generation unit 112 of the light projection unit 110 has four types of polarization directions (0 °, 45 °, 90 °, 135 °) in each of the four divided regions. In this configuration, the plates are set one by one and combined.
On the other hand, the polarization generation unit 112 of the light projecting unit shown in FIG. 8 subdivides the light output region to set a number of divided regions, and sets four types of polarization directions (0 °, 45 °, 90 °, 135 °). °) are arranged in each of the subdivided sections, and a large number of polarizing plates are combined.

FIG. 9 is a diagram illustrating a configuration example of the light receiving unit 120.
The polarizing plate 121 of the light receiving unit 120 illustrated in FIG. 9 also has four types of polarization by subdividing the light input region and setting a large number of divided regions, similarly to the configuration of the polarization generating unit 112 of the light projecting unit 110 illustrated in FIG. In this configuration, polarizing plates having directions (0 °, 45 °, 90 °, 135 °) are arranged in each of the divided sections, and a large number of polarizing plates are combined.

Note that the process of acquiring the reference value and the process of detecting the transparent object are performed using the light receiving signal values received through all the polarizing plates 121.
For example, in the process of acquiring the reference value, the user confirms that the transparent object 170 does not exist in the detection area 150, inputs a processing 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 of the four different observation polarization angles described with reference to FIG. 9 and inputs the received light signals to the received light signal recording unit 131.

The light receiving signal recording unit 131 calculates the following signal value and sets it as a reference value (reference signal).
Reference value: Ia_o = added value of a plurality of light receiving signals at an observation polarization angle of 0 ° without a transparent object,
Reference value: Ib_o = added value of a plurality of light receiving signals at an observation polarization angle of 45 ° without a transparent object,
Reference value: Ic_o = added value of a plurality of light receiving signals at an observation polarization angle of 90 ° without a transparent object,
Reference Tsu: Id_o = added value of a plurality of received light signals at an observation polarization angle of 135 ° without a transparent object,
The optical signal analysis unit 131 stores these four signals (Ia_o, Ib_o, Ic_o, Id_o) in the storage unit 103 as reference values (reference signal values).

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

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

In any one of these determination processes, if any one of the differences is larger than the specified thresholds Th1a to Th1d, it is determined that a transparent object exists.
On the other hand, if all the differences are not larger than the specified thresholds Th1a to Th1d, it is determined that no transparent object exists.

  It should be noted that, similarly to the description with reference to FIG. 7 above, instead of comparing and judging each of the four light receiving signals corresponding to the four types of observation polarization angles with the threshold value, the light reception signal corresponding to each observation polarization angle is obtained. A process of calculating an addition value of a difference between the threshold value and the reference value and determining the presence or absence of a transparent object based on a comparison between the addition value and one threshold value Th1 may be performed.

FIG. 10 is a diagram illustrating another configuration example of the light projecting unit 110.
The light projecting unit 110 illustrated in FIG. 10 has a configuration in which polarized lights having four types of polarization directions (0 °, 45 °, 90 °, and 135 °) are sequentially output in time series.
The polarization generating unit 112 of the light projecting unit 110 shown in FIG. 10 is configured by, for example, one polarizing plate, and rotates this polarizing plate by a predetermined angle (45 °) with time.
With this processing, polarized lights having four types of polarization directions (0 °, 45 °, 90 °, and 135 °) are sequentially output in time series.

FIG. 11 is a diagram illustrating a configuration example of the light receiving unit 120.
The polarizing plate 121 of the light receiving unit 120 illustrated in FIG. 11 is also configured by, for example, one polarizing plate, similar to the configuration of the polarization generating unit 112 of the light projecting unit 110 illustrated in FIG. , At a predetermined angle (45 °).
By this processing, polarized lights having four kinds of polarization directions (0 °, 45 °, 90 °, 135 °) are sequentially input in time series.

  When the configuration shown in FIG. 11 is used, the reference value acquisition process and the transparent object detection process execute the signal acquisition process four times by setting the polarizing plate 121 to four different polarization angles. This is set as one set, and the process is executed by using the light receiving signal value of one set unit.

The reference signal is the following signals. Receiving signal of observed polarization angle of 90 ° without light Id_o = Received signal of observed polarization angle of 135 ° without transparent object

In the transparent object presence / absence determination processing, the difference between the light receiving signal value (Ia, Ib, Ic, Id) through the four types of polarizing plates (a to d) and the reference values (Ia_o, Ib_o, Ic_o, Id_o) is calculated. do it,
The difference value is compared with a threshold value. 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 determination expression is the same as the determination expression described with reference to FIG.

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

The light projecting unit 110 and the light receiving unit 120 of the object detection device 100 illustrated in FIG. 3 can have various configurations, for example, as illustrated in FIGS.
In any of the configurations, the light projecting unit 110 outputs linearly polarized light having four different polarization angles in parallel or sequentially outputs in a time series.
The light receiving unit 120 observes the received light signal based on the plurality of linearly polarized lights, that is, the elliptically polarized light that has passed through the transparent object or the linearly polarized light that has not passed through the transparent object at a plurality of observation polarization angles.
By performing such processing, the accuracy of detecting a transparent object is increased.

[4. (Embodiment 2) Embodiment 2 of an object detection apparatus for detecting a transparent object using polarized light and calculating residual stress]
Next, a description will be given of a second embodiment of the object detection apparatus for detecting a transparent object using polarized light and calculating a residual stress.

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

In the first embodiment, as described with reference to FIGS.
The light projecting unit 110 is configured to output four types of polarized lights having four types of polarization directions (polarization angles).
The light receiving unit 120 is also configured to acquire the observation luminance I (θ) at four different observation polarization angles (θ) as observation values.

In contrast, in the second embodiment,
The light projecting unit 110 is configured to output three types of polarized lights having three types of polarization directions (polarization angles).
The light receiving unit 120 is also configured to acquire observation luminance I (θ) at three different observation polarization angles (θ) as observation values.

Hereinafter, a plurality of exemplary configurations of the light projecting unit 110 and the light receiving unit 120 according to the second embodiment will be described.
FIG. 12 is a diagram illustrating 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 generation unit 112.
FIG. 12A shows a specific configuration example of the polarization generation unit 112.
As shown in FIG. 12A, the polarization generation unit 112 of the light projection unit 110 is configured by a combination of three types of polarizing plates having four types of polarization directions (polarization angles).

More specifically, (0 °, 45 °, 90 °) is a configuration in which polarizing plates having these three types of polarization directions are combined.
FIG. 12 (2) shows the polarization directions (polarization angles) of the three polarizing plates 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 the linearly polarized lights 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 the linearly polarized light having a plurality of different polarization angles output from the light projecting unit 110 via a transparent object or as it is.

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

More specifically, (0 °, 45 °, 90 °) is a configuration in which polarizing plates having these three types of polarization directions are combined.
FIG. 13B shows the polarization directions (polarization angles) of the three polarizing plates 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 (a to c) polarization directions are combined.

An optical signal passing through a polarizing plate 121 obtained by combining polarizing plates having the above three types (a to c) of polarization directions is input to a light receiving sensor 122 and converted into an electric signal corresponding to the amount of light signal (light intensity). The 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 observation luminance I (θ) at three different observation polarization angles (θ) is obtained as the observation value.

Observation luminance I (θ), which is an observation value at three different observation 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 becomes transparent in the detection area 150. It is used to determine whether the object 170 exists.
Further, when it is determined that the transparent object 170 is present in the detection area 150, it is also used for calculating the residual stress inside the transparent object 170.

The process executed using the light projecting unit 110 and the light receiving unit 120 described with reference to FIGS. 12 and 13, that is, the specific process of determining whether or not the transparent object 170 exists in the detection area 150 This will be described with reference to FIGS.
As described above, the light reception signal recording unit 131 inputs the light reception signal of the light reception unit 120 in a state where the transparent object 170 does not exist in the detection region 150 as a preliminary preparation process, 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 the reference value acquisition processing, the actual detection processing 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 a process of the light reception signal recording unit 131 that calculates a reference value based on the light reception signal of the light reception 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 the signals of the three different observation polarization angles described with reference to FIG. 13, and the received light signals are input to the received light signal recording unit 131.
The light receiving signal of the light receiving unit 120 is the following signal.
Ia_o = Reception signal of observation polarization angle 0 ° without transparent object Ib1_o = Reception signal of observation polarization angle 45 ° without transparent object Ib2_o = Reception of observation polarization angle 45 ° without transparent object Signal Ic_o = received signal at observation polarization angle of 90 ° in the absence of a transparent object The optical signal analyzer 131 stores these four signals (Ia_o, Ib1_o, Ib2_o, Ic_o) in the storage unit 103 as reference values (reference signal values). Store.

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

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

The object presence / absence determination unit 132 compares the signal value calculated by the light reception signal recording unit 131 with a reference value stored in the storage unit to determine 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 = received signal at observation polarization angle of 0 ° Ib1 = received signal at observation polarization angle of 45 ° Ib2 = received signal at observation polarization angle of 45 ° Ic = received signal at observation polarization angle of 90 °

  The object presence / absence determining 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. Determine whether or not.

Specifically, for example, a determination process according to the following determination formula is executed.
Light receiving signal values (Ia, Ib1, Ib2, Ic) through the four polarizing plates (a to d);
By calculating the differences from the reference values (Ia_o, Ib1_o, Ib2_o, Ic_o),
The difference value is compared with a threshold value. 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, and 21c,
Th2a, Th2b1, Th2b2, and Th2c are predetermined threshold values.
This threshold value is stored in the storage unit 103.
The above determination formulas 21a to 21c are determination formulas for comparing the difference between the acquired signal value and the reference value at each observation polarization angle and the threshold value (Th2a to Th2c).

When any one of the above (judgment expressions 21a to 21c) is satisfied, that is,
If the difference between the acquired signal value and the reference value at each observation polarization angle is larger than a predetermined threshold value, it is determined that the transparent object 170 exists in the detection area 150.
On the other hand, when all of the above (judgment expressions 21a to 21c) do not hold, that is,
If none of the difference between the obtained signal value and the reference value at each observation polarization angle is larger than a predetermined threshold value, it is determined that the transparent object 170 does not exist in the detection area 150.

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

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

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

As described above, in the configuration of the present disclosure, the transparent object presence / absence determination process uses all of the polarizations having different polarization angles output by the light projecting unit 110. This processing reduces the occurrence of the problem that the detection accuracy is reduced in accordance with, for example, the direction of the transparent object.
Note that 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 item [2. Regarding Stress Detection Processing Using Polarized Light].
The stress determination unit 134 performs a determination process of determining whether the transparent object 170 is defective or non-defective 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 is performed. The residual stress inside the transparent object 170 calculated by the stress calculation unit 133 and its direction are compared with a threshold value to determine whether the transparent object 170 is a good product or a defective product.
The determination result is output to the output unit 104.

  Another configuration example of the light projecting unit 110 and the light receiving unit 120 according to the second embodiment will be described with reference to FIG.

FIG. 16 is a diagram illustrating a configuration example of the light projecting unit 110.
As described above with reference to FIG. 12, the polarization generation unit 112 of the light projection unit 110 includes one polarization plate having three types of polarization directions (0 °, 45 °, and 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 polarization generation unit 112 of the light projecting unit shown in FIG. 16 subdivides the light output region to set a number of divided regions, and sets three types of polarization directions (0 °, 45 °, 90 °). In this configuration, a polarizing plate having a plurality of polarizing plates is arranged in each of the divided sections.

FIG. 17 is a diagram illustrating 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 three types of polarized light, similar to the configuration of the polarization generating unit 112 of the light projecting unit 110 shown in FIG. In this configuration, polarizing plates having directions (0 °, 45 °, 90) are arranged in each of the divided sections, and a large number of polarizing plates are combined.

Note that the process of acquiring the reference value and the process of detecting the transparent object are performed using the light receiving signal values received through all the polarizing plates 121.
For example, in the process of acquiring the reference value, the user confirms that the transparent object 170 does not exist in the detection area 150, inputs a processing 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 of the three different observation polarization angles described with reference to FIG. 17 and inputs the received light signals to the received light signal recording unit 131.

The light receiving signal recording unit 131 calculates the following signal value and sets it as a reference value (reference signal).
Reference value: Ia_o = added value of a plurality of light receiving signals at an observation polarization angle of 0 ° without a transparent object,
Reference value: Ib1_o = added value of a plurality of light receiving signals at an observation polarization angle of 45 ° without a transparent object,
Reference value: Ib2_o = added value of a plurality of light receiving signals at an observation polarization angle of 45 ° without a transparent object,
Reference value: Ic_o = added value of a plurality of light receiving signals at an observation polarization angle of 90 ° without a transparent object,
The optical signal analyzing unit 131 stores these four signals (Ia_o, Ib1_o, Ib2_o, Ic_o) in the storage unit 103 as reference values (reference signal values).

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

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

In any of these determination processes, if any one of the differences is larger than the specified thresholds Th2a to Th2c, it is determined that a transparent object exists.
On the other hand, if all the differences are not larger than the specified thresholds Th2a to Th2c, it is determined that no transparent object exists.

  It should be noted that, similarly to the description with reference to FIG. 15 above, instead of comparing and judging each of the four light receiving signals corresponding to the three types of observation polarization angles with the threshold, the light reception signal corresponding to each observation polarization angle is obtained. A process of calculating an addition value of a difference between the threshold value and the reference value and determining the presence or absence of a transparent object based on a comparison between the addition value and one threshold value Th2 may be performed.

FIG. 18 is a diagram illustrating another configuration example of the light projecting unit 110.
The light projecting unit 110 illustrated in FIG. 18 has a configuration in which polarized lights having three types of polarization directions (0 °, 45 °, and 90 °) are sequentially output in time series.
The polarization generating unit 112 of the light projecting unit 110 illustrated in FIG. 18 includes, for example, one polarizing plate, and rotates the polarizing plate by a predetermined angle (45 °) with time.
With this processing, polarized lights having three types of polarization directions (0 °, 45 °, and 90 °) are sequentially output in time series.

FIG. 19 is a diagram illustrating a configuration example of the light receiving unit 120.
The polarizing plate 121 of the light receiving unit 120 illustrated in FIG. 19 is also configured by, for example, one polarizing plate, similar to the configuration of the polarization generating unit 112 of the light projecting unit 110 illustrated in FIG. , At a predetermined angle (45 °).
With this processing, polarized lights having three types of polarization directions (0 °, 45 °, and 90 °) are sequentially input in time series.

  When the configuration shown in FIG. 19 is used, the reference value acquisition process and the transparent object detection process are performed by setting the polarizing plate 121 to three different polarization angles and executing the signal acquisition process three times. This is set as one set, and the process is executed by using the light receiving signal value of one set unit.

The reference signals are the following signals. Ia_o = Received signal of observation polarization angle 0 ° without transparent object Ib_o = Received signal of observation polarization angle 45 ° without transparent object Ic_o = Transparent object Observed polarization signal at 90 ° without light

In the transparent object presence / absence determination processing, the difference between the light receiving signal value (Ia, Ib, Ic) through the three types of polarizing plates (a to c) and the reference value (Ia_o, Ib_o, Ic_o) is calculated.
The difference value is compared with a threshold value. 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 (determination formula 23)

As described above, the light projecting unit 110 and the light receiving unit 120 of the object detection device 100 illustrated in FIG. 3 can have various configurations, for example, as illustrated in FIGS.
In any configuration, the light projecting unit 110 outputs linearly polarized lights having three different types of polarization angles in parallel or sequentially outputs in a time series.
The light receiving unit 120 observes the received light signal based on the plurality of linearly polarized lights, that is, the elliptically polarized light that has passed through the transparent object or the linearly polarized light that has not passed through the transparent object at a plurality of observation polarization angles.
By performing such processing, the accuracy of detecting a transparent object is increased.

[5. (Embodiment 3) Embodiment 3 of an object detection device that detects a transparent object using polarized light and calculates residual stress]
Third Embodiment Next, a third embodiment of an object detection device that performs transparent object detection using polarization and calculates residual stress will be described.

FIG. 20 illustrates a configuration example of the object detection device 200 according to 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 polarized light posted by the light projecting unit 110 is reflected by the reflector 180 via the detection area, and the reflected light is received by the light receiving unit 120. Has become.
Only the configuration using the reflection plate 180 is different from the first and second embodiments.

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

[6. Other Examples]
Next, other embodiments will be described.
The various configurations of the light emitting unit and the light receiving unit have been described with reference to FIGS. 4 to 19. In addition to these configurations, for example, the light emitting unit outputs polarized light having different wavelengths, and It may be configured to observe polarized light corresponding to each wavelength.

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

  Also on the light receiving unit 120 side, the observation light is R (red), G (green), and B (blue) light of different wavelengths, and the polarization angle of each wavelength light is (0 °, 45 °, 90 °). , 135 °).

As described above with reference to (Equation 1), the phase difference φ of elliptically polarized light generated when linearly polarized light passes through a transparent object depends on the wavelength λ of light.
That is, different elliptically polarized light is generated according to 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. Regarding the sequence of processing executed by the object detection device]
Next, a sequence of processing executed by the object detection device described in each of the above-described embodiments will be described.

The sequence of the process executed by the object detection device shown in FIG. 3 or FIG. 20 will be described with reference to the flowcharts in FIG.
The processing according to the flowcharts shown in FIG. 22 and subsequent figures 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 a storage unit 103.

The flowchart illustrated in FIG. 22 is a flowchart illustrating an entire sequence of a process performed by the object detection device.
The flowchart illustrated 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 illustrated in FIG.
The flowchart illustrated in FIG. 24 is a flowchart illustrating a detailed sequence of the residual stress calculation process in step S105 of the flow illustrated in FIG.

First, an overall sequence of a process executed by the object detection device will be described with reference to a flowchart illustrated in FIG.
Hereinafter, the processing of each step will be sequentially described.

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

(Step S102)
Next, in step S102, a transparent object detection process is performed.
This process is a process for detecting whether or not the transparent object 170 exists in the polarized light passing region in the detection region 20 shown in FIGS.
This process is executed by the light receiving signal recording unit 131 of the data processing unit 130 and the object presence / absence determining 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.

(Step S103)
When the transparent object detection processing is completed in step S102, the result information of the transparent object detection processing 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 according to whether or not a transparent object has been detected as a result of the transparent object detection process in step S102.
If a transparent object is detected in the transparent object detection processing in step S102, the process proceeds to step S105.
On the other hand, if a transparent object has not been detected, the process returns to step S102, and the transparent object detection processing 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, a residual stress detection process for the detected transparent object is executed.
This processing is performed according to the item [2. Regarding Stress Detection Processing Using Polarized Light].
The specific processing sequence will be described later with reference to the flowchart shown in FIG.

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

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

(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 received 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 no transparent object exists in the detection area 150, It is stored in the storage unit 103.

Note that the method of generating the reference value differs depending on the configurations 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 configured as described with reference to FIGS. 4 to 19. Then, 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 processing in step S202 is completed, next, in step S203, the transparent object detection processing is started.

(Steps S204 to S208)
Next, in step S204, a light receiving signal of the light receiving unit 120 is obtained 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 or does not exist in the detection area 150. Based on the signal value, a signal value to be compared with the previously acquired reference value is calculated.

  Further, in steps S <b> 205 to S <b> 206, the object presence / absence determination unit 132 compares the signal value calculated by the light reception signal recording unit 131 with the reference value stored in the storage unit, and determines whether the transparent object 170 is within the detection area 150. Determine if it exists.

  If the difference between the newly acquired signal value and the reference value is larger than a predetermined threshold value, that is, if the determination in step S206 is Yes, the process proceeds to step S207, where it is determined that the transparent object 170 exists in the detection area 150. I 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, where a transparent object It is determined that 170 does not exist.

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

  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.

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

(Step S302)
Next, in step S302, the stress calculator 133 calculates the residual stress and the stress direction of the transparent object using the input signal.
This stress calculation is based on the item [2. Regarding Stress Detection Processing Using Polarized Light].
That is, the residual stress inside the transparent object 170 and its direction are calculated using a plurality of (three or more) 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 and its direction information with a predetermined threshold value, and determines that the transparent object 170 is non-defective. Or defective.

If it is determined that the product is defective, the process proceeds to step S305, and the result of determination that the product is defective 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. Hardware configuration example of object detection device]
Next, an example of a hardware configuration of the object detection device will be described with reference to FIG.
The hardware configuration illustrated in FIG. 25 is a block diagram illustrating an example of a hardware configuration that can be used as the object detection device described in the above-described embodiment.

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

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

  The storage unit 308 connected to the input / output interface 305 includes, for example, a hard disk and stores programs 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.

  A 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 to record or read data.

The light projecting unit 321 corresponds to the light projecting unit 110 of the object detection device illustrated in FIGS. 3 and 20, and projects a plurality of types of polarized light.
The light receiving section 322 corresponds to the light receiving section 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 Configuration of the Present Disclosure]
The embodiment of the present disclosure has been described in detail with reference to the specific embodiment. However, it is obvious that those skilled in the art can modify or substitute the embodiments without departing from the gist of the present disclosure. That is, the present invention has been disclosed by way of example, and should not be construed as limiting. In order to determine the gist of the present disclosure, the claims should be considered.

The technology disclosed in the present specification can have the following configurations.
(1) a light emitting unit that outputs polarized light of at least three or more different polarization directions,
A light receiving unit that receives output light of the light emitting unit at at least three or more different observation polarization angles,
Based on a light receiving signal of the light receiving unit, a data processing unit that determines whether a transparent object is present in an optical path from the light emitting unit to the light receiving unit,
The data processing unit includes:
When the object presence / absence determination unit determines that a transparent object is present in the optical path, a stress calculation for calculating a residual stress of the transparent object using light reception signals of a plurality of different observation polarization angles received by the light reception unit. An object detection device having a part.

(2) The data processing unit includes:
A light receiving signal recording unit that stores light receiving signals of a plurality of different observation polarization angles received by the light receiving unit in a state where no transparent object is present in the optical path in a storage unit,
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 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) An optical path from the light projecting unit to the light receiving unit is a straight optical path,
The object detection device according to (1) or (2), wherein a detection area for detecting the presence or absence of a transparent object is set in a linear optical path between the light projecting unit and the light receiving unit.

(4) An optical path from the light projecting unit to the light receiving unit is an optical path whose direction changes by a reflection plate,
The object detection device according to (1) or (2), wherein a detection area for detecting the presence or absence of a transparent object is set in an optical path whose direction changes by the reflector.

(5) The light projecting unit is configured to output at least three or more types of polarized lights having different polarization directions in parallel,
The object detection device according to any one of (1) to (4), wherein the light receiving unit is configured to input at least three or more types of polarized lights having different polarization directions in parallel.

(6) The light projecting unit is configured to sequentially output at least three or more types of polarized light having different polarization directions,
The object detection device according to any one of (1) to (4), wherein the light receiving unit is configured to sequentially input at least three or more types of polarized light having different polarization directions.

(7) The light emitting unit is configured to output four types of polarized lights 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 polarized lights having polarization directions of 0 °, 45 °, 90 °, and 135 °.

(8) The light projecting unit outputs three types of polarized light 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 is configured to input three types of polarized lights having polarization directions of 0 °, 45 °, and 90 °.

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

(10) The light reception signal recording unit includes:
The storage unit stores at least three or more reference values which are light reception signals of at least three or more different observation polarization angles received by the light receiving unit in a state where no transparent object is present in the optical path,
The object presence determination unit,
A light receiving signal of at least three or more different observation polarization angles received by the light receiving unit and a difference between a reference value of the same observation polarization angle as the light reception signal are calculated,
The object detection device according to any one of (1) to (9), wherein when at least one of the calculated three or more differences is larger than a predetermined threshold value, it is determined that a transparent object exists in the optical path.

(11) The light reception signal recording section includes:
The storage unit stores at least three or more reference values which are light reception signals of at least three or more different observation polarization angles received by the light receiving unit in a state where no transparent object is present in the optical path,
The object presence determination unit,
A light receiving signal of at least three or more different observation polarization angles received by the light receiving unit, and an addition value of a difference between a reference value of the same observation polarization angle as the light reception signal is calculated.
The object detection device according to any one of (1) to (9), wherein when the calculated difference addition value is larger than a predetermined threshold value, it is determined that a transparent object exists in the optical path.

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

(13) The object detection device further includes:
A stress determination unit configured to compare the calculation data of the stress calculation unit with a predetermined threshold to determine whether the residual stress of the transparent object is a residual stress to be determined as a defective product (1) The object detection device according to any one of (1) to (11).

(14) An object detection method executed by the object detection device,
The object detection device,
A light emitting unit that outputs polarized light of at least three or more different polarization directions,
A light receiving unit that receives output light of the light emitting unit at at least three or more different observation polarization angles,
Based on a light receiving signal of the light receiving unit, a data processing unit that determines whether a transparent object is present in an optical path from the light emitting unit to the light receiving unit,
The data processing unit includes:
When it is determined that a transparent object is present in the optical path, an object detection is performed by performing a stress calculation step of calculating a residual stress of the transparent object using light reception signals of a plurality of different observation polarization angles received by the light receiving unit. Method.

(15) a program for causing the object detection device to execute an object detection process;
The object detection device,
A light emitting unit that outputs polarized light of at least three or more different polarization directions,
A light receiving unit that receives output light of the light emitting unit at at least three or more different observation polarization angles,
Based on a light receiving signal of the light receiving unit, a data processing unit that determines whether a transparent object is present in an optical path from the light emitting unit to the light receiving unit,
The program, the data processing unit,
A program for executing, when it is determined that a transparent object exists in the optical path, a stress calculating step of calculating a residual stress of the transparent object using light receiving signals of a plurality of different observation polarization angles received by the light receiving unit.

  Further, the series of processes described in the specification can be executed by hardware, software, or a combination of both. When processing by software is performed, the program recording the processing sequence is installed in a memory in a computer built in dedicated hardware and executed, or the program is stored in a general-purpose computer capable of executing various processing. It can be installed and run. For example, the program can be recorded in a recording medium in advance. In addition to installing the program from the recording medium to the computer, 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.

  The various processes described in the specification may be executed not only in chronological order according to the description, but also in parallel or individually according to the processing capacity of the device that executes the processes or as necessary. Further, in this specification, a 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 the 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 polarized light are realized.
Specifically, for example, it has a light projecting unit that outputs at least three or more different polarizations, a light receiving unit that receives at least three or more different observation polarization angles, and a data processing unit. The data processing unit stores the received light signal of the light receiving unit in a state where no transparent object exists in the optical path in the storage unit as a reference value, and stores the received light signal of the plurality of different observation polarization angles received by the light receiving unit 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 of the plurality of different observation polarization angles received by the light receiving unit.
With this configuration, an apparatus and a method for detecting a transparent object and calculating the residual stress of the transparent object using polarized light are realized.

REFERENCE SIGNS LIST 10 light projecting unit 11 polarizing plate 20 light receiving unit 21 polarizing plate 30 space 50 transparent object 100 object detecting device 101 input unit 102 control unit 103 storage unit 104 output unit 110 light projecting unit 111 light output unit 112 polarization generating unit 120 light receiving unit 121 Polarizing plate 122 Light receiving sensor 130 Data processing unit 131 Light receiving signal recording unit 132 Object existence determining unit 133 Stress calculating unit 134 Stress determining unit 150 Detection area 170 Transparent object 180 Reflecting plate 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 Light emitting unit 322 Light receiving unit

Claims (15)

A light emitting unit that outputs polarized light of at least three or more different polarization directions,
A light receiving unit that receives output light of the light emitting unit at at least three or more different observation polarization angles,
Based on a light receiving signal of the light receiving unit, a data processing unit that determines whether a transparent object is present in an optical path from the light emitting unit to the light receiving unit,
The data processing unit includes:
An object detection device including a stress calculation unit configured to calculate a residual stress of the transparent object using light reception signals of a plurality of different observation polarization angles received by the light reception unit when it is determined that a transparent object exists in the optical path; . The data processing unit includes:
A light receiving signal recording unit that stores light receiving signals of a plurality of different observation polarization angles received by the light receiving unit in a state where no transparent object is present in the optical path in a storage unit,
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 presence / absence of a transparent object in the optical path based on the light receiving signal recorded in the light receiving signal recording unit. Item 1. The object detection device according to Item 1. An optical path from the light emitting unit to the light receiving unit is a linear optical path,
The object detection device according to claim 1, wherein a detection area for detecting the presence or absence of a transparent object is set in a linear optical path between the light projecting unit and the light receiving unit. An optical path from the light projecting unit to the light receiving unit is an optical path whose direction is changed by a reflector,
The object detection device according to claim 1, wherein a detection area for detecting the presence or absence of a transparent object is set in an optical path whose direction changes by the reflector. The light emitting unit is configured to output at least three or more types of polarized light having different polarization directions in parallel,
The object detection device according to claim 1, wherein the light receiving unit is configured to input at least three or more types of polarized lights having different polarization directions in parallel. The light emitting unit is configured to sequentially output at least three or more types of polarized light having different polarization directions,
The object detection device according to claim 1, wherein the light receiving unit is configured to sequentially input at least three or more types of polarized light having different polarization directions. The light emitting unit is configured to output four types of polarized lights having polarization directions of 0 °, 45 °, 90 °, and 135 °,
2. The object detection device according to claim 1, wherein the light receiving unit is configured to input four types of polarized lights having polarization directions of 0 °, 45 °, 90 °, and 135 °. 3. The light emitting unit is configured to output three types of polarized lights having polarization directions of 0 °, 45 °, and 90 °,
2. The object detection device according to claim 1, wherein the light receiving unit is configured to input three types of polarized lights having polarization directions of 0 °, 45 °, and 90 °. 3. The light emitting unit is configured to output at least three or more types of polarized lights having different wavelengths and different polarization directions,
The object detection device according to claim 1, wherein the light receiving unit is configured to input at least three or more types of polarizations having different wavelengths and different polarization directions. The light receiving signal recording unit,
The storage unit stores at least three or more reference values which are light reception signals of at least three or more different observation polarization angles received by the light receiving unit in a state where no transparent object is present in the optical path,
The object presence determination unit,
A light receiving signal of at least three or more different observation polarization angles received by the light receiving unit and a difference between a reference value of the same observation polarization angle as the light reception signal are calculated,
The object detection device according to claim 2, wherein when at least one of the calculated three or more differences is larger than a predetermined threshold value, it is determined that a transparent object exists in the optical path. The light receiving signal recording unit,
The storage unit stores at least three or more reference values which are light reception signals of at least three or more different observation polarization angles received by the light receiving unit in a state where no transparent object is present in the optical path,
The object presence determination unit,
A light receiving signal of at least three or more different observation polarization angles received by the light receiving unit, and an addition value of a difference between a reference value of the same observation polarization angle as the light reception signal is calculated.
The object detection device according to claim 2, wherein when the calculated difference addition value is larger than a predetermined threshold value, it is determined that a transparent object exists in the optical path. The stress calculator,
The object detection device according to claim 1, wherein a residual stress and a stress direction of the transparent object are calculated using light reception signals of at least three or more different observation polarization angles received by the light receiving unit. The object detection device may further include:
A stress judging unit that judges whether or not the residual stress of the transparent object is the residual stress to be judged as a defective product by comparing the calculation data of the stress calculating unit with a predetermined threshold value. 2. The object detection device according to 1. An object detection method executed by the object detection device,
The object detection device,
A light emitting unit that outputs polarized light of at least three or more different polarization directions,
A light receiving unit that receives output light of the light emitting unit at at least three or more different observation polarization angles,
Based on a light receiving signal of the light receiving unit, a data processing unit that determines whether a transparent object is present in an optical path from the light emitting unit to the light receiving unit,
The data processing unit includes:
When it is determined that a transparent object is present in the optical path, an object detection is performed by performing a stress calculation step of calculating a residual stress of the transparent object using light reception signals of a plurality of different observation polarization angles received by the light receiving unit. Method. A program for executing an object detection process in the object detection device,
The object detection device,
A light emitting unit that outputs polarized light of at least three or more different polarization directions,
A light receiving unit that receives output light of the light emitting unit at at least three or more different observation polarization angles,
Based on a light receiving signal of the light receiving unit, a data processing unit that determines whether a transparent object is present in an optical path from the light emitting unit to the light receiving unit,
The program, the data processing unit,
A program for executing, when it is determined that a transparent object exists in the optical path, a stress calculating step of calculating a residual stress of the transparent object using light receiving signals of a plurality of different observation polarization angles received by the light receiving unit.

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