KR20090098666A - Optics sensing device - Google Patents

Abstract

An optical sensor apparatus is provided to detect the foreign material which has a small size. An optical sensor apparatus(1) includes a light projector(3), a light receiver(4) and a signal processing unit(6). The light projector projects the detected light(2) on the tested material. The light receiver receives the detected light. The signal processing unit determines the existence of foreign material by processing the output of the light receiver. The light receiver comprises a two dimension image pickup element, CCD(Charge-Coupled Device)(11). The signal processing unit comprises a sample hold circuit(12), an A/D converter(13), a memory(14), a CPU(Central Processing Unit)(15), a liquid crystal display unit(16) and a control key(17). The sample hold circuit maintains the pixel signal read from the CCD.

Description

Optical sensor device {OPTICS SENSING DEVICE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical sensor device that detects foreign matter or the like present in a detection area by transmitting light toward the detection area and receiving light received through the detection area.

Background Art Conventionally, as an optical sensor device, an apparatus that detects the presence or absence of a foreign substance on the basis of a change in the total amount of received light in a light receiver when a parallel light is transmitted from a light emitter to a detection area and the parallel light is received by the light receiver is known. It is used.

As an example of such an apparatus, Patent Literature 1 discloses the presence or absence of a change in the amount of received light in a light receiver caused by the foreign material being moved relative to the light emitter and the light receiver, and the foreign material traverses the optical path of parallel light emitted from the light emitter. On the basis of this, a technique for detecting the presence or absence of foreign matter is disclosed.

In such an apparatus, specifically, as shown, for example in FIG. 16, the laser beam of the width | variety L0 projected from the light projector 300 propagates on the board | substrate 500 in parallel with respect to the said board | substrate. Is detected by the light receiver 400. The board | substrate 500 is a test | inspection object to which the foreign material adheres, and is test | inspected, and is supported by the stone slab 510. In FIG. 16, the propagation direction of a laser beam is shown by the arrow DZ. The substrate 500 is moved relative to the light emitter 300 and the light receiver 400 together with the stone platform 510. The moving direction is a direction perpendicular to the arrow DZ and the arrow DY (vertical direction), and is a direction perpendicular to the ground.

As illustrated in FIG. 17, when a foreign material 501 exists on the substrate 500, a part of the parallel light emitted by the light projector 300 is blocked by the foreign material 501. As a result, the total amount of received light detected by the light receiver 400 is reduced. On the basis of such a change in the total amount of received light, the presence or absence of foreign matter and the like is detected.

In addition, Patent Literature 2 discloses a technique in which a light receiving area of a light receiver is divided in a direction in which a foreign material moves relatively, and the presence or absence of a foreign material on a substrate is detected based on the light receiving amount of each divided area.

Specifically, as shown in FIG. 18, the detection light 200 is transmitted from the light emitter 300 toward the light receiver 400 in the direction indicated by the arrow DZ, and the substrate 500 is light-emitting 300. ) And the light receiving area of the light receiver 400 is in the horizontal direction, which is the moving direction of the substrate 500, in the system relatively moved in the horizontal direction as shown by the arrow A with respect to the light receiver 400. Divided to list.

19 shows an arrangement of light receiving regions in the light receiver 400 viewed from the light projector 300 side.

As shown in FIG. 18, the light receiving surface 401 of the light receiver 400 is provided with the light receiving area 402 which is a detection target of the light receiving amount, and the light receiving area 402 is divided into a plurality of divisions arranged in the horizontal direction. Regions 402A through 402J.

In Patent Literature 2, for each of the divided regions 402A to 402J, the average light received amount for each measurement period is calculated, and compared with the average light received amount calculated before a predetermined number of times, the presence or absence of foreign matter is determined. In the technique disclosed in Patent Document 2, the ratio of the shielding area of the foreign material 501 to the area of each of the divided regions 402A to 402J can be large, and it is possible to change the total amount of received light in the light receiver. Based on the foreign material inspection technique for detecting the presence or absence of foreign matters, the detection sensitivity is improved.

Patent Document 1: Japanese Patent Application Laid-Open No. 2002-1195

Patent Document 2: Japanese Patent Application Laid-Open No. 2006-351441

In the optical sensor device as described above, the improvement of the detection accuracy is always hopeless. In particular, in recent years, when the downsizing of parts is accelerated, foreign matters having smaller dimensions cause defects, and therefore, detection thereof is necessary.

In the case of detecting the presence or absence of foreign matter on the basis of the change in the total amount of received light in the light receiver, when the foreign matter becomes small, the change in the amount of received light with respect to the total amount of received light becomes small, and the detection sensitivity is insufficient.

When the light-receiving area of the light receiver is divided in the relative moving direction of the foreign material, and the presence or absence of the foreign material on the substrate is detected based on the amount of light received in each divided region, diffraction occurs when the foreign material becomes small, and the diffracted light is centered on the foreign material. The intensity distribution pattern (diffraction pattern) of the light intensity is generated radially. When the plurality of light receiving regions are arranged in the relative moving direction of the foreign material, in order to detect the change in the intensity of the received light intensity caused by the diffraction pattern, In order to set the width | variety of the movement direction of each light reception area | region smaller than the period of a diffraction pattern, and to grasp | ascertain the change of light reception amount as a time change accompanying a movement, it is necessary to shorten an exposure time according to a movement speed. For this reason, the light reception amount obtained is limited and there is a limit to high sensitivity.

The present invention has been devised in view of the above circumstances, and an object thereof is to provide an optical sensor device capable of reliably detecting the presence or absence of a foreign matter, even when the size of the foreign matter that needs to be detected is reduced.

An optical sensor device according to an aspect of the present invention transmits a detection light to a space on an upper surface including an upper surface of a flat member from a light transmitting portion provided on one end surface side of a flat member placed on a flat support surface, and on the other end surface side. An optical sensor device for receiving a detection light from a light receiving portion provided at the same time and detecting foreign matter attached to the flat plate member by moving the detection light and the flat plate member in a direction parallel to the support surface. And a storage unit for storing the teeth, and a processing unit, wherein the light receiving unit is a range in which the detection light is incident in a direction perpendicular to the support surface in a state where a flat member without foreign matter is placed on the support surface. It includes a plurality of light receiving regions arranged in a direction away from the support surface from the end of the near side, the storage unit is for each light receiving region The reference value is stored, and the processing unit calculates a difference value from the received values of each of the received regions generated based on the received amount of light received in the entire of the received regions, and the corresponding reference values, respectively. And if any difference exceeds the determination threshold, it is determined that there is a foreign material.

Preferably, the light receiving unit repeatedly receives the detection light incident on each of the light receiving regions at a predetermined measurement period, and the processing unit repeatedly calculates the difference value for each measurement period, and the detection light and the flat member are relatively The detection light in the moving direction and the dimensions of each light receiving region are longer than the dimensions calculated by the product of the measurement period and the movement speed of the relative movement.

Further, preferably, the foreign material of at least a predetermined size existing in the predetermined inspection range between the light transmitting portion and the light receiving portion is detected, and the dimension of the direction perpendicular to the supporting surface of each light receiving region is such that the predetermined foreign material is inspected. When the light is closer to the light-receiving portion of the range, the diffracted light generated by the foreign matter is smaller than half of the diffraction period of the diffraction pattern generated by the light-receiving portion.

Preferably, the memory unit stores, as a reference value, the light reception value of each light reception region generated based on the total light reception amount received in each light reception region in a state where the flat member without foreign matter is placed on the support surface.

Preferably, a display unit for displaying an image is further provided, and the light receiving unit includes a two-dimensional imaging element having an imaging area composed of pixels arranged in two dimensions, and each of the light receiving regions is provided in plural in each of the imaging areas. The storage unit also stores an image previously acquired by the imaging region of the two-dimensional imaging element as a reference image, and the processing unit is an image and the reference image acquired by the imaging region of the two-dimensional imaging element. The difference image with respect to each other and the set light receiving area are displayed on the display unit by superimposing the pixel positions on the difference image.

Preferably, the reference image is an image acquired in a state where the flat member without foreign matter is placed on the support surface.

Further, preferably, an input unit for inputting a plurality of pixel ranges set as respective light receiving regions in the imaging region of the two-dimensional imaging element is further provided, and the processing unit includes the plurality of pixel ranges input from the input unit as the respective light receiving regions. The pixel positions correspond to the difference images, are overlaid and displayed on the display unit, and the plurality of input pixel ranges are set as the respective light receiving regions.

An optical sensor device according to another aspect of the present invention transmits a detection light to a space on an upper surface including an upper surface of a flat member from a light transmitting portion provided on one end surface side of a flat member placed on a flat support surface, and on the other end surface side. An optical sensor device for receiving a detection light from a light receiving portion provided at the same time and detecting foreign matter attached to the flat plate member by moving the detection light and the flat plate member in a direction parallel to the support surface. And a storage unit for storing the teeth, and a processing unit, wherein the light receiving unit is a range in which the detection light is incident on a direction perpendicular to the support surface in a state where the flat member without foreign matter is placed on the support surface. It includes a plurality of light receiving regions arranged in a direction away from the support surface from the end of the nearest side, the storage unit, each light receiving region The reference value corresponding to the memory is stored, and the processing unit calculates a ratio from the received values of the respective light receiving regions generated based on the light receiving amount received in the entire light receiving region with respect to each of the light receiving regions and the corresponding reference values, respectively. If the ratio exceeds any of the determination threshold, it is determined that there is a foreign material.

According to the present invention, a plurality of light-receiving light beams are arranged in a direction parallel to the support surface in which the detection light and the plate-shaped member are relatively moved in a direction parallel to the support surface on which the flat member to be detected as foreign matter is placed. The received signal generated based on the received amount of light received in each region is compared with the reference received signal, respectively, and if any comparison result exceeds the determination threshold, it is determined that there is foreign matter.

Thereby, even if the received light amount of the detection light from the light-transmitting part is reduced by the said object by the dimension of the object desired to detect as a foreign material, the object can be detected using diffracted light. In addition, when the size of the object is large, the object can be detected from the variation in the amount of light received by shielding the detection light.

In the foreign material detection, a diffraction pattern generated concentrically around the foreign material moves on the light receiving area. At least one of the plurality of light receiving areas arranged in the direction perpendicular to the supporting surface passes through the center of the diffraction pattern. Since it is arrange | positioned in the light reception area | region and the time change of the light reception amount accompanying a movement of a diffraction pattern occurs relatively slowly in this light reception area | region, an exposure time can be set long. Or, the width | variety of the moving direction of a light receiving area can be set long. As a result, the detection sensitivity of the foreign material can be improved by increasing the light reception amount of the weak diffracted light.

EMBODIMENT OF THE INVENTION Hereinafter, one Embodiment of the optical sensor apparatus of this invention is described, referring drawings.

In addition, the same code | symbol is attached | subjected to the same component in each figure, and detailed description is not repeated.

[First Embodiment]

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a block diagram showing the overall configuration of an optical sensor device according to the present invention, and Fig. 2 is a block diagram showing the arrangement of a light emitter and a light receiver when this optical sensor device is applied to foreign material detection.

The optical sensor device 1 of the present embodiment includes a light projector 3 for transmitting the detection light 2 onto a workpiece 50 as an inspection object such as a glass substrate, and a number for receiving the detection light 2. And a signal processing device 6 configured to signal-process the madness 4 and the output of the light receiver 4 to determine the presence or absence of the foreign matter 51 on the work 50. With respect to the work 50, As shown in the arrow A of FIG. 2, the light emitter 3 and the light receiver 4 move the foreign material 51 present on the workpiece 50 while being moved by the light receiver 4. Detection is based on the change of. In addition, the foreign material 51 is not limited to the case where it exists on the workpiece | work 50, but exists also under the workpiece | work 50, and therefore can detect even when the surface of the workpiece | work 50 rises and is shielded. It is. In addition, the film-forming material is apply | coated to the surface of the workpiece | work 50, such as a glass substrate in which the inspection of the presence or absence of the foreign material 51 was completed, by the coating apparatus which is not shown in figure.

The light projector 3 includes a semiconductor laser 8 driven by the laser drive circuit 7, a collimating lens 9 which uses light from the semiconductor laser 8 as parallel light, and an opening 10A. The slit 10 which has is provided, and it transmits the detection light 2 on the workpiece | work 50.

On the other hand, the light receiver 4 is equipped with the CCD (charge-coupled device) 11 which is a two-dimensional imaging element, and the signal processing apparatus 6 is a CCD 11, as shown in FIG. A sample hold (S / H) circuit 12 for holding a pixel signal read from the sample, and an A / D converter 13 for converting the output of the sample hold circuit 12 to A / D (analog / digital) conversion. On the basis of the image memory 14 storing the A / D-converted pixel data and the pixel data of the image memory 14, and a processing unit for determining the presence or absence of foreign matter as described later, a reference value and a determination threshold value. A CPU (central processing unit) 15 having a function as a storage unit for storing, a liquid crystal display unit 16 for displaying an image picked up by the CCD 11 based on pixel data of the image memory 14, and And various operation keys 17 as input sections. The image memory 14 also has a function as a storage unit for storing reference images.

FIG. 3: is a figure which shows typically the surface in which the CCD 11 of the light receiver 4 was installed, and corresponds to the figure which looked at the light receiver 4 from the light projector 3 side.

Referring to FIG. 3, in the detection surface 4A in which the CCD 11 of the light receiver 4 is provided, a measurement region 40 in which a part of the imaging area of the CCD 11 receives light from the light projector 3. This measurement area 40 is further divided into a plurality of divided areas (divided areas 41 to 44) along a direction perpendicular to the upper surface of the work 50, and each divided area 41 to 44. The amount of received light is measured for each.

In the present embodiment, the opening 10A of the slit 10 of the light projector 3 is a rectangle that is long in the moving direction of the light projector 3 and the light receiver 4 (the direction of the arrow A in FIG. 2), for example. For example, it is formed in the rectangle of 1 mm x 5 mm, and the slit-shaped detection light 2 from the light projector 3 is transmitted so that the measurement area 40 of the CCD 11 may be covered.

FIG. 4 shows the projection of light emitted by the light projector 3 based on the change of the distance between the foreign material 51 and the light receiver 4 present on the workpiece 50 in the optical sensor device 1 of FIG. 1. It is a figure for demonstrating the change of the light reception state in CCD11.

4, the positional relationship of the light projector 3, the light receiver 4, and the detection light 2 of FIG. 2 is shown typically in FIG. In addition, in FIG.4 (D), as the position of this water 51 on the workpiece | work 50, three places of foreign materials 51A-51C are shown.

4A shows the amount of received light in the measurement region 40 when foreign matter exists at the position of the foreign material 51A. 4B shows the amount of received light in the measurement region 40 when foreign matter exists at the position of the foreign material 51B. 4C shows the light reception amount in the measurement region 40 when foreign matter exists at the position of the foreign material 51C. 4A to 4C, the light receiving amount is shown as an average value obtained by averaging the light receiving amount in the horizontal direction for each position in the vertical direction, and divided regions 41 to 44 corresponding to the position in the vertical direction. This dashed line is shown.

In addition, in FIG.4 (A)-FIG.4 (C), the broken line has shown the light reception amount when the foreign material 51 (foreign materials 51A-51C) does not exist. In this specification, such a light reception amount is called appropriately "light reception amount of a blank."

In addition, in FIG.4 (A)-FIG.4 (C), hatching is drawn in the area | region corresponding to the division area | region 44 corresponding to the position of the vertical direction like foreign materials 51A-51C.

The distance from the slit 10A to the CCD 11 is, for example, 4.0 m. The distance from the foreign material 51A to the CCD 11 is, for example, 1.5 m and the distance from the foreign material 51B to the CCD 11 is, for example. For example, the distance from the foreign material 51C to the CCD 11 is 1.0 m, for example, 0.5 m.

As understood from FIG. 4 (A)-FIG. 4 (C), the light-receiving aspect in the measurement area | region 40 is changing by where the position of the foreign material 51 is located in the foreign material 51A-51C. .

In FIG. 4A, the light receiving amount is lowered with respect to the light receiving amount of the blank from the lower end in the vertical direction of the measurement region 40 to substantially above the position in the vertical direction in which the foreign material 51A is present.

Also in FIG. 4B, the light receiving amount is lower than that of the blank until the interruption of the divided region 41.

In FIG. 4C, the region where the light receiving amount is lower than the light receiving amount of the blank continues from the lower end of the measurement region 40, but is returned to the light receiving amount of the blank at the interruption of the divided region 43.

In addition, in any of FIG. 4 (A)-FIG. 4 (C), when a change in the light reception amount from the lower end of the measurement area 40 is seen, once the light reception amount decreases, the light reception amount increases as it goes upwards. The light received amount of the blank is exceeded. Regarding FIG. 4C, after again lowering the light receiving amount of the blank, the light receiving amount of the blank is again exceeded.

It is considered that the light reception amount changes in this way from the lower end of the measurement area 40 upwards is because light transmission from the light projector 3 is diffracted by foreign matter.

As shown in Figs. 4A to 4C, the amount of received light in the entire measurement area 40 changes depending on the distance from the light receiver 4 (CCD 11) of the foreign material 51. To detect the presence or absence of the foreign material 51 on the basis of the amount of light received in the light receiving area of the entire measurement area 40, if the foreign material 51 exists at a position close to the light receiver 4, the presence of the foreign material 51 is detected. I think it is difficult. This will be described with reference to FIG. 5.

FIG. 5 shows the total amount of received light ("o" in FIG. 5) of the measurement area 40 when the distance between the foreign material 51 and the CCD 11 changes. In addition, in FIG. 5, the total light-receiving amount ("o" in FIG. 5) of the measurement area | region 40 when the foreign material 51 does not exist is shown by reference.

As understood from FIG. 5, as the foreign material 51 exists at a position close to the CCD 11, the total amount of received light in the measurement area 40 is close to the amount of received light when the foreign material 51 does not exist. have. That is, as the foreign material 51 is present at a position close to the CCD 11, the difference in the total amount of received light as compared to when it is not present becomes small, and it is difficult to detect the presence of the foreign material 51 based on the total amount of received light. . This is considered to be due to the fact that the foreign material 51 receives a lot of diffracted light by the foreign material 51 in the measurement region 40 as the foreign material 51 exists at a position close to the CCD 11.

In addition, as illustrated by hatching in FIGS. 4A to 4C, the presence or absence of the foreign material 51 can be determined only by the light reception amount of the light reception region 44 that is a part of the measurement region 40. I think it's possible. However, when the presence or absence of the foreign material 51 is determined in this manner, it is considered that the existence of the foreign material 51 is difficult to detect when the foreign material 51 exists at a position far from the light receiver 4. This will be described with reference to FIG. 6.

6 shows the total amount of received light ("o" in FIG. 6) of the divided region 44 when the distance between the foreign material 51 and the CCD 11 changes. In addition, in FIG. 6, the total light-receiving amount ("●" in FIG. 6) of the division area 44 when the foreign material 51 does not exist is shown by reference.

As understood from FIG. 6, as the foreign material 51 is located at a position far from the CCD 11, the total amount of received light in the divided region 44 is close to the amount of received light when the foreign material 51 is not present. have. That is, as the foreign material 51 is located at a position far from the CCD 11, the difference in the total amount of received light with respect to when it does not exist becomes small, and it is difficult to detect the presence of the foreign material 51 based on the total amount of received light. .

In the present embodiment, for each of the divided regions 41 to 44, the difference value of the average concentration when the foreign material 51 is present or not is calculated. An example of the calculated difference value is shown in FIG.

In FIG. 7, each of the divided regions 41 to 44 is shown as the divided region N (N = 1 to 4) on the horizontal axis. In the present embodiment, the average concentration when the foreign material is present is shown by "(circle)" (an image of the present time) connected by a dashed line, and the average concentration when the foreign material does not exist is "(circle)" connected by a broken line. The difference before and after the foreign matter is shown by "(circle)" (average concentration difference) shown by the solid line. The "T turn" in FIG. 7 is mentioned later.

Then, in any one of the difference values for the divided regions 41 to 44 as shown in FIG. 7, the foreign material is determined on the work 50 by determining whether or not the predetermined threshold value (P1 in FIG. 7) is exceeded. It is determined whether or not present in the. In addition, the threshold is, for example, a predetermined margin (approximately twice the value of noise) to a noise value relating to the detection of the respective average concentrations of the respective divided regions 41 to 44. In the example shown in FIG. 7, the light reception amount M1 of the divided region 43 (N = 3) exceeds the threshold. Thereby, it is judged that the foreign material 51 exists on the workpiece | work 50 (or below the workpiece | work 50) which opposes the measurement area | region 40 at the time when such a light reception amount was measured.

In the present embodiment, a part of the area that can be measured by the CCD 11 is the measurement area 40. The size of the measurement area 40 is set to 1.0 mm in height x 3.0 mm in width, for example. Accordingly, the divided regions 41 to 44 are 0.25 mm long by 3.0 mm wide.

In addition, the size of the foreign material 51 is about 100 micrometers or more, for example.

In addition, the dimension in the vertical direction (vertical direction) of the divided regions 41 to 44 is preferably equal to or larger than the dimension in the vertical direction of the object intended to be detected as the foreign material 51. Thus, the distance between the centers in the vertical direction of the divided regions 41 to 44 is also preferably equal to or larger than the dimension in the vertical direction of the object intended to be detected as the foreign material 51 in accordance with it.

In addition, in this embodiment, although the area of the division areas 41-44 is 0.75 mm <2>, it is preferable that the area is 1 mm <2> or less.

In addition, in this embodiment, although the CCD 11 is 3.2 mm x 3.46 mm, it is preferable that it is 2 mm x 2 mm or more in consideration of optical-axis alignment of the light projector 3 and the light receiver 4.

In the present embodiment, the relative moving foreign material 51 receives the pixel signals constituting the divided regions 41 to 44 of the CCD 11 while passing through the divided regions 41 to 44. It is possible to set so that it can be performed at least once.

In this embodiment, the width | variety along the moving direction of the measurement area | region 40 is 3 mm, and the maximum movement speed is 400 mm / s, for example, Therefore, division area | region 41-the 44) The time required for the foreign material 51 to pass through the preceding detection region is, for example, 7.5 ms, which is larger than the acceptance period of the CCD 11 of 7.0 ms, so that the foreign material 51 passes. In the meantime, the image signal can be accepted.

In this embodiment, the presence or absence of the foreign material 51 is determined as follows based on the light reception amounts of the divided regions 41 to 44.

That is, in the CPU 15 of the signal processing apparatus 6 of FIG. 1, the light reception density of the plurality of pixels constituting the divided regions 41 to 44 for each acceptance period (7.0 msec) of the CCD 11 (hereinafter, The average value (average concentration) of only the density) is calculated for each divided area of the divided areas 41 to 44, respectively.

Next, the absolute value of the difference (average concentration difference) between the average density value for every division area 41-44 computed, and the average concentration for every division area 41-44 computed before predetermined time (T time), respectively. It calculates for every division area 41-44, respectively.

Then, it is determined whether or not the maximum value in the absolute values of the average concentration differences for each of the divided regions 41 to 44 has exceeded a predetermined threshold value, and when the threshold value is exceeded, it is determined that there is a foreign object and corresponding determination output Can be given to the outside, and based on this determination output, appropriate measures can be taken to notify the presence of foreign objects or to stop the processing on the work 50. In addition, a threshold value adds a predetermined | prescribed margin value to the noise level of the signal from the pixel which comprises this division area about each of the division areas 41-44, for example, the value of about twice the noise level. Becomes

Here, the average concentration difference for each of the divided regions 41 to 44 calculated on the basis of the detected value at that time corresponds to the "image of the present time" in FIG. 7, and the average concentration before the T-th time is the "T time before" in FIG. 7. Image ”and the absolute value of these differences corresponds to the“ average density difference ”in FIG. 7. In the present embodiment, the reference light receiving signal is configured by the average concentration value before T turns.

Thus, using the difference between the average concentration value of the present time and the average concentration before a predetermined time (T time), when the light quantity change is occurring slowly in the space, the change in the amount of received light due to the foreign matter is apparent from the balance with the moving speed. This is to compare with the obtained viewpoint. Therefore, this predetermined time (T time) is appropriately determined according to the degree of change in the amount of light assumed, for example, several times to several tens of times, and in the present embodiment, for example, ten times. .

As a modification of the determination mode of the presence or absence of the foreign matter according to the present embodiment, the present average concentration and a predetermined threshold value (for example, the memory in the CPU 15) are stored without calculating the difference from the average concentration before the predetermined time. ) May be compared to determine the presence or absence of foreign objects.

8 is a flowchart of the determination processing of the foreign material detection described above. As shown in this figure, first, the average concentrations D1 (0) to Dn (0) are calculated for each of the plurality of divided regions 41 to 44 of 1 to n (n = 4), and the calculated values are calculated. The average concentration value is stored in the memory in the CPU 15 (step n1). The absolute value of the average concentration difference between the average concentration value for each divided region and the average concentration (D1 (T) to Dn (T)) for each divided region 41 to 44 calculated before the predetermined time (T times) ( | D1 (T) -D1 (0) |-| Dn (T) -Dn (0) |) are calculated, and the average for each divided area 41-44 calculated before predetermined time (T time). The concentrations D1 (T) to Dn (T) are erased (step n2).

Next, it is determined whether the maximum value in the absolute value of the calculated average concentration difference is greater than the predetermined threshold value (step n3), and when it is not large (when the maximum value is less than or equal to the threshold value), it waits until the next acceptance measurement cycle. (Step n4). On the other hand, when the said maximum value is larger than a threshold value, a judgment output is turned on as a foreign material (step n5).

Next, the evaluation experiment of foreign material detection by the optical sensor device 1 of the present embodiment will be described. In addition, the evaluation experiment was carried out by making the space | interval with respect to the optical axis direction of parallel light between the slit 10A and CCD11 4000 mm, and arrange | positioning the 3.5 mm square glass plate of 0.1 mm thickness as the foreign material 51, lost.

9 shows the results of the evaluation experiment. In Fig. 9, the solid line &quot;# &quot; denotes the absolute value of the average concentration difference among the divided areas 41 to 44 obtained by dividing the measurement area 40 in the vertical direction as shown in Fig. 3 (see Fig. 7). ) Shows the average concentration difference over the partitions where) is largest. In addition, in FIG. 9, "(DELTA)" shows the average concentration difference with respect to the divided area | region where the absolute value of the mean concentration difference of the largest with respect to the divided area | region obtained by dividing the measurement area | region 40 into four horizontally as a comparison is largest. Doing. Hereinafter, the experimental result indicated by "●" is appropriately referred to as data in the case of vertical division, and the experimental result indicated by "Δ" is referred to as data in the case of horizontal division.

9 has shown the data obtained by arrange | positioning the said glass plate as a pile of the foreign material 51. FIG. In FIG. 9, the horizontal axis represents the distance in the optical axis direction from the light projector 3 (slit 10A) to the position where the glass plate (foreign material 51) is disposed. Specifically, in FIG. 9, the data of the distance is 200 mm, 500 mm, 1000 mm, 1500 mm, 2000 mm, 2500 mm, 3000 mm, 3500 mm, and 3800 mm, respectively.

As understood from FIG. 9, in the data in the case of the horizontal division, the average concentration difference is the threshold value P4: even though the foreign material 51 is disposed on the work 50 in the vicinity where the distance exceeds 2500 mm. Like P1 described above, it is determined based on the noise level or the like). On the other hand, in the data in the case of vertical division, the average concentration difference exceeds the threshold at any distance in the measurement result of FIG. 9. That is, in the case where the measurement area 40 is divided only in the horizontal direction as in the prior art, when the foreign material 51 exists at a position far from the light emitter 3, it is assumed that the existence cannot be detected. According to the embodiment, even if the foreign material 51 is arrange | positioned in any position on the optical path between the light projector 3 and the light receiver 4, presence of the said foreign material 51 can be detected.

In addition, in the present embodiment described above, the length of the respective divided regions 41 to 44 in the direction perpendicular to the upper surface of the work 50 as described above is such that the predetermined foreign matter is the most in the inspection range. When the light is closer to the light receiving portion, it is preferable that the diffracted light generated by the foreign matter is smaller than the diffraction period of the diffraction pattern generated by receiving the light at the light receiving portion. As can be seen from FIG. 4C, the length in the direction perpendicular to the upper surface of the workpiece 50 of each divided region 41 to 44 is preferably smaller than half of the diffraction period of the diffraction pattern. Do.

In addition, in this embodiment, the range of the direction perpendicular | vertical to the upper surface of the workpiece | work 90 of the measurement area 40 exists in the light projected from the said light-transmitting part, and the light received by the said light-receiving part exists when the said foreign material does not exist. It is a range.

In addition, in this embodiment, as understood from FIG. 4 etc., the light transmitter 3 may shield a part of light by the workpiece | work 50 in the state in which the light projection has no foreign material on the workpiece | work 50. FIG. It is preferred to be installed. Moreover, the light receiver 4 is provided so that the light transmitted by the light projector 3 may receive light including the edge shielded by the workpiece | work 50. As shown in FIG. 3 and 4, the measurement region 40 and the divided regions 41 to 44 are connected to the light receiver 4 with respect to the direction perpendicular to the upper surface of the workpiece 50, for example. The light from the light projector 3 is arranged on the light-receiving side starting from the position of the edge in the light received by the light source.

[Second Embodiment]

Since the whole structure of the 2nd Embodiment of the optical sensor apparatus of this invention can be made into the same thing as 1st Embodiment demonstrated with reference to FIG. 1 and FIG. 2, overlapping description is not repeated. .

In addition, in the optical sensor device 1 of the present embodiment, the measurement region 40 is perpendicular to the upper surface of the work 50 as shown in FIG. 10 as the first to sixth divided regions. It is also divided in the horizontal direction with respect to the upper surface.

And in the optical sensor device 1 of this embodiment, as shown in FIG. 11 about each of the 1st-6th division area | region, it averages based on the image of this time and the image before T times. The difference in density is calculated, and whether the foreign material 51 exists on the workpiece 50 by whether or not the average concentration difference exceeds a threshold (P2: determined in accordance with the noise level or the like as in P1 above). Is determined.

In addition, in the present embodiment, the detection density in the divided regions adjacent to each other in the vertical direction adjacent to each other in the vertical direction instead of the difference with the image before the T turns is determined. Based on the difference, the presence or absence of the foreign material 51 can also be determined. The data used for such a determination is shown in FIG.

With reference to FIG. 12, the average density difference with respect to the 1st division area and the 2nd division area which adjoin each other perpendicularly among the 1st division area | region from the 6th division area shown as "the present image" in FIG. Is shown as data when the Nth division area is "(2-1)". In FIG. 12, the difference in the average concentration difference between the third divided region and the fourth divided region that are adjacent to each other in the vertical direction is shown as data when the Nth divided region is "(4-3)". . In FIG. 12, the difference in the average concentration difference between the fifth divided region and the sixth divided region adjacent to each other in the vertical direction is shown as data when the Nth divided region is "(6-5)". .

In addition, in FIG. 12, as a reference, the difference between a 1st division area and a 2nd division area, and the 3rd division area which concerns on the average concentration difference in each of the 1st-6th division area measured before T times. And the difference between the fourth divided region and the difference between the fifth divided region and the sixth divided region are shown by a broken line.

As can be understood from FIG. 12, the data when the foreign material 51 exists in a solid line includes more than a threshold value (P3: determined based on a noise level or the like as in P1 above), but is connected by a broken line. The data exceeding the threshold is not included in the data when the foreign material 51 does not exist. Thereby, the difference between the divided regions adjacent in this vertical direction is calculated, and the presence or absence of the foreign material 51 on the workpiece 50 can also be determined by whether or not the difference includes a threshold value.

By calculating the difference between the divided regions adjacent in the vertical direction in this manner, the influence of the light shielded by the foreign matter 51 is detected in one adjacent divided region, and the foreign matter 51 in the other divided region. In the case where the influence of the diffracted light is detected, it is considered that a particularly large difference value can be obtained, and it is considered effective for the detection of the presence or absence of the foreign matter 51 having a small dimension.

In addition, as shown in FIG. 10, when dividing | dividing a division area also in the parallel direction, the foreign material 51 moves to the relative movement (direction of the arrow A of FIG. 2) of the light projector 3 and the light receiver 4. In addition, in FIG. As a result, it is necessary to set the moving speed so that the reception of the pixel signal by the CCD 11 constituting each divided area is performed at least once while passing through each divided area.

[Other Modifications, etc.]

1) array of partitions

In each of the embodiments described above, the measurement region 40 is divided in the vertical direction to define a divided region. In addition, when the division area is arrange | positioned so that the position of each division area in the perpendicular direction may be different with respect to the upper surface of the workpiece | work 50 at least, it must necessarily be aligned linearly in the direction perpendicular to the upper surface of the workpiece | work 50. As shown in FIG. 13, as shown in the divided regions 41X to 45X, a deviation may occur in the horizontal direction.

2) Installation of Windproof

In addition, in each embodiment described above, as shown to FIG.14 (A) and FIG.14 (B) above the workpiece | work 50 used as a detection object, the flow of air of a room crosses a detection area | region. For reasons such as avoiding the above, it is preferable that the wind chamber 511 is provided.

In addition, FIG. 14 (B) corresponds to the figure at the time of seeing the light receiver 4 side from the light projector 3 side. As shown in FIG. 13, the installation position of the windshield 511 is preferably installed at, for example, a position about 5 mm in height from the stone platform 510.

3) Display of difference image

In the optical sensor device 1, the CPU 15 determines the difference in density between the presence and absence of the foreign material 51 with respect to each pixel obtained in the entire measurement area of the CCD 11. The display unit 16 may be displayed. An example of the screen displayed in such a case is shown in FIG.

Referring to FIG. 15, on the screen 700, an image indicating the concentration difference is displayed in the display field 710.

Specifically, in the display field 711, the density difference with respect to the entire measurement area of the CCD 11 is shown as a color image (monoclosure in the drawing). The display color in the display field 711 is displayed based on the correspondence relationship between the display color and the concentration difference shown in the display field 740.

In other words, the CPU 15 stores the light-receiving concentration at the time when one of the foreign materials 51 is present and one of the non-existent objects 51 is measured for all the pixels in the entire measurement area of the CCD 11. At the time when the other is measured, the light receiving density is stored, the difference is calculated for each pixel, and the obtained difference value is converted into a pixel of color based on the correspondence displayed in the display field 740, The display field 711 is displayed.

In the display field 711, end face indicator lines 712 and 714 are displayed.

The cross section leader line 712 is displayed to indicate the cross section position in the horizontal direction, and the cross section leader line 714 is displayed to indicate the cross section position in the vertical direction. In the screen 700, the distribution of the difference value with respect to the cross section indicated by the cross-sectional indicator line 712 is displayed in the concentration distribution display field 713. In addition, the distribution of the difference value about the cross section indicated by the cross section leader line 714 is displayed in the concentration distribution display column 715.

In the display field 711, the edge 710A corresponding to the measurement area 40 is displayed. The display position of the edge 710A indicates where the measurement area 40 is set in the measurement area of the CCD 11.

The display position in the display field 711 of the edge 710A can be changed by appropriately operating the operation key 17 or the like by the user. In addition, the CPU 15 changes the area for acquiring the light reception density as the measurement area 40 so as to correspond to the display position.

In addition, the CPU 15 stores the captured image of the CCD 11 when the foreign material 51 does not exist in the image memory 14 on the basis of an operation on the operation key 17 by the user. Is displayed in the display field 720 together with the image memory 14 based on the operation of the operation key 17 by the user on the captured image of the CCD 11 when the foreign material 51 is present. In addition, the display field 730 can be displayed.

4) Judging the existence of foreign objects based on rain

In each of the embodiments described above, the difference between the average concentration (received value) when foreign matter is present and the average concentration (reference value) when no foreign matter exists in each divided region is calculated by whether or not the threshold is exceeded. Although the presence of a foreign material is judged, the ratio of a light reception value and a reference value may be calculated instead, and the presence of a foreign material may be judged by whether the ratio exceeds the threshold value. In addition, instead of displaying the difference image, a ratio image in which the ratio of density is calculated may be displayed for each corresponding pixel of the image when the foreign material is present and the image when the foreign material is not present.

5) Use of optical sensor device

In addition, in each embodiment described above, although the example which the optical sensor apparatus was applied to the detection of the foreign material on a glass substrate was demonstrated, the aspect to which the optical sensor apparatus of this invention is applied is not limited to this, Film, metal, paper, etc. It is considered that the present invention can also be applied to the detection of foreign matters related to the sheet-shaped inspection target. In addition, it is considered that the present invention can be applied not only to foreign material detection but also to the detection of lint of other objects, for example, yarn.

It should be thought that each embodiment disclosed this time is an illustration and restrictive at no points. The scope of the present invention is shown not by the above description but by the scope of a claim, and it is intended that the meaning of a claim and equality and all the changes within a range are included. In addition, the technique disclosed in each embodiment is intended to be applied in combination as much as possible including a modification.

BRIEF DESCRIPTION OF THE DRAWINGS The block diagram which shows the whole structure of the optical sensor apparatus which is one Embodiment of this invention.

FIG. 2 is a configuration diagram showing an arrangement of a light emitter and a light receiver when the optical sensor device of FIG. 1 is applied to foreign material detection. FIG.

FIG. 3 is a diagram schematically illustrating a surface on which a CCD is installed of the light receiver of FIG. 1. FIG.

4 is a view for explaining a change in a light receiving state in a CCD of light emission by a light projector based on a change in distance between a foreign material and a CCD present on a work in the optical sensor device of FIG. 1.

5 is a diagram showing an example of the total amount of received light in the measurement area when the distance between the foreign material and the CCD in the optical sensor device of FIG. 1 changes.

FIG. 6 is a diagram showing an example of the total amount of received light of the divided area located at the bottom of the measurement area when the distance between the foreign material and the CCD is changed in the optical sensor device of FIG. 1. FIG.

FIG. 7 is a diagram showing a difference value of the total amount of received light when each of the divided regions in the optical sensor device of FIG. 1 is not referred to when foreign matter exists. FIG.

8 is a flowchart of a determination process of foreign material detection performed in the optical sensor device of FIG. 1.

9 shows the results of evaluation experiments in the optical sensor device of FIG. 1.

It is a figure which shows typically the divisional aspect of the measurement area | region in 2nd Embodiment of the optical sensor device of this invention.

FIG. 11 is a diagram showing a difference between average concentrations when foreign matter is present and non-existing, with respect to each of the divided regions shown in FIG. 10; FIG.

FIG. 12 is a diagram showing a difference value of average concentrations of adjacent divided regions in the vertical direction when foreign matter is present in the divided region shown in FIG. 10; FIG.

It is a figure which shows the modification of the structure of the division area in 1st and 2nd embodiment of the optical sensor device of this invention.

It is a figure which shows the modification of the whole structure in the 1st and 2nd embodiment of the optical sensor apparatus of this invention.

Fig. 15 is a diagram showing an example of a screen displayed in the optical sensor device of the present invention.

16 is a view for explaining foreign material detection by the prior art disclosed in Patent Document 1. FIG.

17 is a view for explaining foreign material detection by the prior art disclosed in Patent Document 1. FIG.

18 is a view for explaining foreign material detection by the prior art disclosed in Patent Document 2. FIG.

19 is a view for explaining foreign material detection by the prior art disclosed in Patent Document 2. FIG.

(Explanation of symbols for the main parts of the drawing)

1: Optical sensor device 2: Parallel light

3: emitter 4: receiver

4A: detection surface 6: signal processing device

7: laser driving circuit 8: semiconductor laser

9: collimated lens 10: slit

10A: Opening 11: CCD

12: sample hold circuit 13: A / D converter

14: image memory 15: CPU

16 liquid crystal display 17 operation keys

40: measurement area

41 to 44, 41A to 46A: divided region

50: Walk 51: foreign body

510: stone tablet

Claims (8)

From the light transmitting portion provided on one end surface side of the flat member placed on the flat support surface, the detection light is transmitted to a space on the upper surface including the upper surface of the flat member, and the detection light is received by the light receiving portion provided on the other end surface side. An optical sensor device for detecting a foreign matter adhered to a flat plate member by moving the detection light and the flat plate member in a direction parallel to the support surface. A storage unit for storing reference values, Equipped with a processing unit, The light-receiving portion is a range in which the detection light is incident in a direction perpendicular to the support surface in a state where the flat member without foreign matter is placed on the support surface, and is supported from the end of the side closest to the support surface. A plurality of light receiving regions arranged in a direction away from the memory, wherein the storage unit stores reference values corresponding to the respective light receiving regions, The processing unit calculates a difference value from each of the light receiving regions generated based on the light receiving amount received in the entire light receiving region with respect to each of the light receiving regions, and a corresponding reference value, respectively, wherein any one of the difference values is a determination threshold value. The optical sensor device which determines that there exists a foreign material when it exceeds. The method of claim 1, The light receiving unit repeatedly receives the detection light incident on each of the light receiving regions at a predetermined measurement period, The processing unit repeatedly calculates the difference value for each measurement period, The dimension of the said detection light and each light receiving area | region in the direction which a detection light and a flat plate member move relatively is longer than the dimension computed by the product of the measurement period and the movement speed of the said relative movement. Sensor device. The method according to claim 1 or 2, The optical sensor device detects a foreign material of at least a predetermined size existing in a predetermined inspection range between the light transmitting portion and the light receiving portion, The dimension in the direction perpendicular to the support surface of each of the light receiving regions is generated when diffraction light generated by the foreign matter is received at the light receiving portion when the predetermined foreign material is closest to the light receiving portion of the inspection range. An optical sensor device having a dimension smaller than half of the diffraction period of the diffraction pattern. The method of claim 1, The storage unit stores, as the reference value, a light receiving value of each light receiving region generated based on the total light receiving amount received in each of the light receiving regions in a state where the plate-shaped member not attached to the foreign material is placed on the support surface. Optical sensor device. The method of claim 1, Also provided with a display unit for displaying an image, The light receiving portion includes a two-dimensional imaging element having an imaging area consisting of pixels arranged in two dimensions, Each light receiving region is set to include a plurality of pixels in the imaging region, respectively. The storage section further stores an image acquired in advance by the imaging area of the two-dimensional imaging element as a reference image, The processing unit, An optical sensor characterized in that the difference image between the image acquired by the imaging region of the two-dimensional imaging element and the reference image, and each set light receiving region are superimposed on the difference image in correspondence with the pixel position; Device. The method of claim 5, The said reference image is an optical sensor apparatus characterized by the image acquired in the state in which the flat plate member which a foreign material did not adhere on the said support surface. The method of claim 5, Also provided with an input unit for inputting a plurality of pixel ranges set as the respective light receiving regions in the imaging region of the two-dimensional imaging element, The processing unit superimposes the plurality of pixel ranges input from the input unit and displays the plurality of pixel ranges as the respective light receiving regions as the respective light receiving regions. Optical sensor device, characterized in that the setting. From the light transmitting portion provided on one end surface side of the flat member placed on the flat support surface, the detection light is transmitted to a space on the upper surface including the upper surface of the flat member, and the detection light is received by the light receiving portion provided on the other end surface side. An optical sensor device for detecting a foreign matter adhered to a flat plate member by moving the detection light and the flat plate member in a direction parallel to the support surface. A storage unit for storing reference values, Equipped with a processing unit, The light-receiving portion is a range in which the detection light is incident in a direction perpendicular to the support surface in a state where the flat member without foreign matter is placed on the support surface, and is supported from the end of the side closest to the support surface. A plurality of light receiving areas arranged in a direction away from The storage unit stores a reference value corresponding to each of the light receiving regions, The processing unit calculates a ratio from the received values of each of the received regions and the corresponding reference values, respectively, based on the received amount of light received in the entire received region with respect to each of the received regions, and any ratio exceeds the determination threshold. Optical sensor device characterized in that it is determined that there is foreign matter.

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