JP2007033295A - Inspection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inspection device for automatically regulating an imaging system to obtain high inspection performance in a short time. <P>SOLUTION: The inspection device for inspecting the existence of a defect in a transported light diffusion sheet comprises a line sensor camera, a line-like light source, and a light source position regulating means. The line sensor camera images the light diffusion sheet by scanning the light diffusion sheet in the transporting direction and rectangular direction. The line-like light source is movement-stoppably disposed at a position of the light diffusion sheet on the non-imaging side, and permeably illuminates an imaged region of the line sensor camera in the light diffusion sheet. The light source position regulating means regulates the position so as to stop the movement of the line-like light source at a predetermined position determined based on a light diffusion characteristic of the light diffusion sheet. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  It belongs to the technical field of inspecting the quality of optical characteristics, appearance, etc. of a light diffusion sheet based on a captured image. In particular, the present invention relates to an inspection apparatus capable of automatically adjusting an imaging system so that a light diffusion sheet to be inspected can be inspected from a large degree to a small degree of light diffusion.

  The light diffusion sheet is used for the purpose of bringing light from a point light source such as an LED or a linear light source such as a straight tube fluorescent lamp close to a surface light source. In addition, the light diffusion sheet is used for the purpose of improving the light emission characteristics of a liquid crystal display, a projection television, and the like so that a clear image can be seen from a wider angle. In the manufacture of such a light diffusion sheet, not only the appearance defects such as foreign matter, scratches, dirt, etc., which are problems in general sheets, but also optical characteristics such as haze (HAZE), total light transmittance, etc. There is a need to inspect defects that are out of standards.

An invention of an apparatus that detects both light diffusion defects and foreign object defects in such a light diffusion sheet by a single inspection is known (Patent Document 1). In the present invention, by providing the strip-shaped light adjusting member in the imaging system, the light beam incident on the imaging area of the line sensor camera as the imaging means is adjusted. This adjustment makes it possible to detect defects such as foreign matters and optical defects in the light diffusion sheet with higher sensitivity.
JP 2002-48726

  However, if the light diffusion sheet item to be inspected changes, the optical characteristics differ depending on the item, so if you always want to obtain high inspection performance, you need to adjust the imaging system every time the item changes There is. Even with the above-described band-shaped light control member, optimum inspection performance cannot be obtained unless the position of the light diffusion sheet is adjusted according to the item each time the item is changed. Such adjustment is difficult, but if it is a remanufactured item, implementation is not impossible by referring to past manufacturing conditions. However, adjustment is extremely difficult for new production items, and it takes a lot of time to complete proper adjustment. In the meantime, the loss caused by stopping the manufacturing apparatus is extremely large.

  The present invention has been made to solve the above problems. The purpose is to provide an inspection apparatus that can automatically adjust the imaging system to obtain high inspection performance, and that can be adjusted in a short time that does not change for both new and remanufactured items. It is in.

An inspection apparatus according to claim 1 of the present invention is an inspection apparatus for inspecting the presence or absence of defects in a transported light diffusion sheet, comprising a line sensor camera, a line light source, and a light source position adjusting means, The line sensor camera images the light diffusing sheet by scanning in a direction perpendicular to the transfer direction of the light diffusing sheet, and the line light source is provided to be able to stop moving to a position on the non-imaging side of the light diffusing sheet. The light diffusion sheet illuminates the imaging area of the line sensor camera, and the light source position adjusting means adjusts the position of moving the line light source to a predetermined position determined by the light diffusion characteristics of the light diffusion sheet. It is a thing.
An inspection apparatus according to a second aspect of the present invention is the inspection apparatus according to the first aspect, wherein the predetermined position is arranged such that the greater the degree of light diffusion of the light diffusion sheet, the more the line-shaped light source is aligned with the optical axis of the line sensor camera. The line light source is positioned closer to the optical axis of the line sensor camera as the light diffusion degree of the light diffusion sheet is smaller.
An inspection apparatus according to a third aspect of the present invention is the inspection apparatus according to the first or second aspect, wherein the movement direction in the movement stop is parallel to the traveling direction of the light diffusion sheet. is there.
An inspection apparatus according to a fourth aspect of the present invention is the inspection apparatus according to any one of the first to third aspects, further comprising an exposure amount adjusting unit that automatically adjusts an exposure amount to an appropriate value after the position adjustment. The exposure amount adjustment means, in the operation of increasing the exposure amount, sets the priority of the operation as the light amount of the light source, the analog gain of the line sensor camera, the aperture of the imaging lens of the line sensor camera, the line rate of the line sensor camera, and the exposure. In the operation of decreasing the amount, the priority of the operation is the line rate, the diaphragm, the analog gain, and the light amount, and at least one of them is operated.
An inspection apparatus according to a fifth aspect of the present invention is the inspection apparatus according to any one of the first to fourth aspects, further comprising a data processing unit, and the data processing unit detects at least a foreign substance defect in the light diffusion sheet. And a process for detecting a light diffusion defect, and a detection result is output so that the contents of the defect can be understood.

According to the inspection apparatus of the first aspect of the present invention, the light diffusion sheet is imaged by the line sensor camera that scans in a direction perpendicular to the transfer direction of the light diffusion sheet, and the movement can be stopped at a position on the non-imaging side of the light diffusion sheet. The line-shaped light source provided on the light-diffusing sheet illuminates the imaging area of the line sensor camera in the light-diffusing sheet, and the light source position adjusting means stops moving the line-shaped light source to a predetermined position determined by the light-diffusing characteristics of the light-diffusing sheet. Done. That is, the position of the line light source is set to an appropriate position by the light diffusion characteristics of the light diffusion sheet to be inspected. Therefore, it is possible to provide an inspection apparatus that can automatically adjust the imaging system to obtain high inspection performance, and that can perform the adjustment in a short time that does not change for both newly produced items and remanufactured items.
According to the inspection apparatus of claim 2 of the present invention, the predetermined position is a position where the linear light source is further away from the optical axis of the line sensor camera as the degree of light diffusion of the light diffusion sheet is larger. The smaller the degree of diffusion, the closer the line-shaped light source is to the optical axis of the line sensor camera. According to the present invention, as the light diffusion degree is larger, the line-shaped light source is moved away from the line sensor camera, and as the light diffusion degree is smaller, the proper position can be obtained.
Moreover, according to the inspection apparatus which concerns on Claim 3 of this invention, the moving direction in a movement stop is a parallel direction with respect to the running direction of a light-diffusion sheet. Therefore, it is possible to reduce the installation space of the line light source and to prevent mechanical interference with other members.
According to the inspection apparatus of the fourth aspect of the present invention, in the operation of increasing the exposure amount by the exposure amount adjustment means for automatically adjusting the exposure amount to an appropriate value after the position adjustment, the priority of the operation is determined by the light source. The amount of light, the analog gain of the line sensor camera, the aperture of the imaging lens of the line sensor camera, and the line rate of the line sensor camera. In the operation to reduce the exposure amount, the priority of the operation is the line rate, aperture, analog gain, and light amount. And at least one of them is manipulated. Therefore, the exposure amount in imaging can be automatically set to appropriate exposure.
According to the inspection apparatus of the fifth aspect of the present invention, at least the processing for detecting the foreign substance defect in the light diffusion sheet and the process for detecting the light diffusion defect are performed by the data processing unit, and the detection result shows the defect content. Is output. Therefore, the detection result is output so that the content of the defect can be understood.

Next, embodiments of the present invention will be described with reference to the drawings. 1 to 4 are diagrams showing the configuration of the inspection apparatus according to the present invention. In FIG. 1, the imaging system and the transport system are shown as schematic diagrams. In FIG. 2, a modification of the imaging system is shown as a schematic diagram. In FIG. 3, the overall configuration is shown as a pictorial diagram. As shown.
1 to 4, 1 is a line sensor camera, 11 is a line sensor element, 12 is a drive circuit, 12 is a lens diaphragm, 2 is an illumination unit, 21 is a high frequency lighting power source, 22 is a fluorescent lamp, and 23 is a fluorescent lamp moving. Means: 3 is a processing unit, 4 is a control unit, 5 is a transport unit, 51 is a PLC (programablle logic controller), 52 is a transport unit, 6 is a server, and 100 is a light diffusion sheet.

  As already described, the light diffusion sheet 100 is a sheet that changes the radiation characteristics of light. It is used for the purpose of bringing light from point light sources and line light sources closer to a surface light source. In addition, the light diffusion sheet 100 is used for applications that improve the light emission characteristics of the display so that an image can be satisfactorily viewed from a wider angle. Known optical properties for evaluating the light diffusion sheet 100 include haze (HAZE), total light transmittance, and the like. In the manufacture of light diffusing sheets, it is necessary to inspect defects in which their optical characteristics are out of standards. In addition, it is necessary to inspect for defects in appearance such as foreign matter, scratches, and dirt which are problems in general sheets.

  In the inspection apparatus of the present invention, in order to suitably perform these inspections in the manufacturing process, adjustment of imaging is performed so as to be an optimal imaging system with respect to the light diffusion characteristics of the light diffusion sheet 100 (described later). . In the example shown in FIG. 1, the light diffusion sheet 100 is a long sheet (web), and handling such as transportation and storage is performed in the form of a winding body. When inspecting the light diffusion sheet 100, as shown in FIG. 1, a winding body is set on the unwinding portion of the inspection apparatus. And after unwinding from a winding body and imaging for the test | inspection with respect to the light-diffusion sheet 100 is performed, a winding body is again formed in the winding part of an inspection apparatus. The unwinding part and the winding part are parts constituting the conveying means of the conveying part 5 shown in FIG. 4 (described later).

The line sensor camera 1 is an image pickup means for picking up an image of the light diffusion sheet 100 that is an inspection object and obtaining a picked-up image. As shown in FIG. 1, in the inspection apparatus of the present invention, the direction of scanning (main scanning) by the line sensor camera 1 for imaging is perpendicular to the conveyance direction (sub-scanning direction) in the light diffusion sheet 100 or The direction is close to a right angle.
The angle at which the line sensor camera 1 looks at the light diffusing sheet 100 is a predetermined angle deviating from the vertical direction with respect to the surface of the light diffusing sheet 100 in the example shown in FIG. This expected angle is determined as an angle at which the defect to be detected, that is, the above-mentioned optical characteristics and appearance defect can be detected well.

  As the line sensor camera 1, a known line sensor camera including a line sensor 11, a drive unit 12, a lens unit 13, a housing, and the like can be used. The line sensor 11 is an integrated circuit such as a charge coupled device (CCD) or a metal oxide semiconductor (MOS), and is a photosensor that can read out photocharges in a time series by arranging a plurality of light receiving elements in a straight line. The drive unit 12 is a circuit for causing the line sensor 11 to perform an imaging operation, and includes an amplifier, a drive circuit, an A / D (analog to digital) converter, a memory, an input / output circuit, and the like. The lens unit 13 forms a light image to be imaged on the line sensor 11 and adjusts the amount of received light (exposure amount), and includes an imaging lens (imaging lens), a diaphragm mechanism, and the like. The control unit 4 inputs the aperture value designated by the processing unit 3 to the aperture mechanism, and the control unit 4 operates the aperture mechanism to set the aperture value of the imaging lens to the designated aperture value.

The line sensor camera 1 operates under the control of the control unit 4 as shown in FIG. For example, the image capturing is performed in synchronization with the conveyance of the light diffusion sheet 100 by the conveyance unit 5 and an imaging signal is output, the operation of the aperture mechanism described above, and the like. In addition, an imaging signal output by imaging by the line sensor camera 1 is output to the processing unit 3 and stored in an image memory in the processing unit 3 (described later).
The output of the line sensor camera 1 may be either an analog signal or a digital signal. As the line sensor camera 1, a color line sensor camera capable of detecting a color tone is used when detecting a defect related to the color tone. A black and white line sensor camera is used when detecting a defect unrelated to color tone.

  The illumination unit 2 is illumination means for the line sensor camera 1 to image the light diffusion sheet 100 with transmitted light. As shown in FIG. 4, the illumination unit 2 includes a high-frequency lighting power source 21, a fluorescent lamp 22, a fluorescent lamp moving means 23, and the like. The fluorescent lamp 22 is disposed at a position where the imaging optical axis of the line sensor camera 1 extends through the imaging area of the light diffusion sheet 100 (a position facing the line sensor camera 1) or a position shifted from the position. As the light source of the line sensor camera 1 having a linear imaging region, a light source having a linear light emitting region is suitable. The fluorescent lamp 22 is an example of a light source having a linear light emitting region, and the light source in the present invention is not limited to a fluorescent lamp.

  The high frequency lighting power source 21 is a power source that supplies power for lighting the fluorescent lamp 22 at a high frequency. When the exposure time of the line sensor camera 1 is taken as a scale by the combination of the phosphor afterglow characteristics and the high-frequency lighting in the white fluorescent lamp 2, there is substantially no variation in the amount of radiant light in the illumination means 2. As shown in FIG. 4, the high-frequency lighting power source 21 inputs a signal for controlling its operation (power on / off, power supply amount, etc.) from the control unit 4.

  The fluorescent lamp moving means 23 performs position adjustment to stop moving the fluorescent lamp 22 to a predetermined position determined by the light diffusion characteristics in the light diffusion sheet 100. That is, the fluorescent lamp moving means 23 is a light source position adjusting means. As the predetermined position, the fluorescent lamp moving means 23 sets the fluorescent lamp 22 to a position farther from the optical axis of the line sensor camera 1 as the light diffusion degree of the light diffusion sheet 100 is larger. Further, the smaller the light diffusion degree of the light diffusion sheet 100 is, the closer the fluorescent lamp 22 is to the optical axis of the line sensor camera 1.

  For example, a haze (HAZE) value can be applied as the degree of light diffusion serving as the reference for the movement. A table representing the relationship between the haze value and the predetermined position in the light diffusion sheet 100 to be inspected is prepared in advance. A table can be experimentally obtained as the position (predetermined position) of the fluorescent lamp 22 in the light diffusion sheet 100 having specific light diffusion characteristics (haze value) where the degree of light diffusion and the appearance defects are easy to detect. Referring to the table, the fluorescent lamp moving means 23 stops moving the fluorescent lamp 22 to a predetermined position. The value indicating the degree of light diffusion is not necessarily a haze value. For different values of the measurement method of the degree of light diffusion, a table representing the relationship between the value in the measurement method and a predetermined position may be prepared in advance and the table may be referred to.

  In the example illustrated in FIG. 1, the moving direction when the fluorescent lamp moving unit 23 stops moving is parallel to the traveling direction (conveying direction) of the light diffusion sheet 100. A known moving mechanism can be applied to the movement stopping mechanism of the fluorescent lamp moving means 23. For example, a linear movement mechanism that linearly moves the stage by rotating a ball screw (ball nut) with a step motor can be applied. In the mechanism, the fluorescent lamp 22 can be stopped at a predetermined position by manipulating the number of pulses output to the step motor.

  Such movement stop by the fluorescent lamp moving means 23 is operated by the control unit 4. That is, the control unit 4 inputs a predetermined position designated by the processing unit 3, and the control unit 4 performs control so that the fluorescent lamp moving unit 23 stops moving the fluorescent lamp 22 with the predetermined position as a target position. The light diffusion characteristics of the light diffusion sheet 100 to be inspected, such as the haze value, and a table representing the relationship between the haze value and the predetermined position are input by the inspection device from the server 6 before the inspection is started, and Store in memory. Based on the haze value and the table, the processing unit 3 derives a predetermined position of the fluorescent lamp 22 and outputs it to the control unit 4. The controller 4 outputs an operation signal (operation amount) to the fluorescent lamp moving means 23 with the predetermined position as a target position, and stops moving the fluorescent lamp 22 to the predetermined position.

A modified example of the movement stop by the fluorescent lamp moving means 23 will be described with reference to FIG. FIG. 2A shows a system in which a plurality of fluorescent lamps 22a, 22b,... With different positions are arranged and only the fluorescent lamp at a predetermined position is lit. Although there is no mechanical movement, there is virtually no difference from mechanical movement. In this case, the fluorescent lamp moving means 23 is a means for lighting only the fluorescent lamp at a predetermined position designated by the processing unit 3.
FIG. 2B is basically the same as the example shown in FIG. In FIG. 1, a diagram is shown in which the movement stops at the downstream side in the conveyance of the light diffusion sheet 100 with the position where the imaging optical axis of the line sensor camera 1 extends through the imaging region of the light diffusion sheet 100 as a base point. In FIG. 2B, a diagram is shown in which the movement stops at the upstream side in the conveyance of the light diffusing sheet 100 with the position where the imaging optical axis of the line sensor camera 1 extends through the imaging region of the light diffusing sheet 100 as a base point. ing.
FIG. 3C shows a configuration in which the line sensor camera 1 is moved instead of moving the fluorescent lamp 22. Since the positional relationship between the line sensor camera 1 and the fluorescent lamp 22 is relative, is substantially the same as the example shown in FIG.

  The processing unit 3 includes an image storage unit that inputs an analog signal or a digital signal output from the line sensor camera 1 and stores it as a captured image (input image), that is, an image memory. The processing unit 3 performs data processing such as extracting defects from the image stored in the image memory and determining pass / fail. In addition, the processing unit 3 performs data processing related to settings, operations, and the like related to the inspection apparatus, data processing related to the user interface, and the like.

  Data processing relating to the setting of the inspection device performed by the processing unit 3 includes data processing for deriving a predetermined position of the fluorescent lamp 22 based on the haze value of the light diffusion sheet 100 and a table created in advance. Further, there is data processing related to exposure amount adjustment for automatically adjusting the exposure amount when the line sensor camera 1 captures an image after the position adjustment of the fluorescent lamp 22 to an appropriate value. Basically, the light diffusion sheet 100 having a larger degree of light diffusion moves the fluorescent lamp 22 away from the optical axis of the line sensor camera 1 and simultaneously increases the exposure amount. As a method for increasing the exposure amount, there are methods such as increasing the light amount of the fluorescent lamp 22, increasing the analog gain of the line sensor camera 1, and opening the lens aperture (described later).

Data processing for deriving a predetermined position of the fluorescent lamp 22 in the data processing performed by the processing unit 3 will be described.
First, when the light diffusion sheet 100 to be inspected, that is, the inspection item is determined, the operator downloads data related to the inspection item from the server 6 to the processing unit 3. The data related to the inspection item includes the product name, serial number, number of winding bodies, web length of each winding body, optical characteristics (haze value) of the light diffusion sheet 100, table, inspection standard (allowable range), etc. is there.
Next, when the operator inputs to instruct the position adjustment of the fluorescent lamp 22, the processing unit 3 starts data processing relating to the position adjustment. Since the table is a table showing the relationship between the haze value and the predetermined position, the processing unit 3 refers to the table and derives the predetermined position corresponding to the haze value. The processing unit 3 outputs the derived predetermined position of the fluorescent lamp 22 to the control unit 4.
A table representing the relationship between the haze value and the predetermined position is prepared in advance by experiments or the like and stored in the server 6. The relationship between the haze value and the predetermined position is determined so that a suitable imaging condition can be obtained in examining the light diffusion characteristics. Thereby, it becomes possible to test | inspect the test object from which a light diffusion characteristic differs, ie, the light-diffusion sheet 100, with one test | inspection apparatus.

Data processing for adjusting the exposure amount in the data processing performed by the processing unit 3 will be described.
When the operator inputs an instruction to adjust the exposure amount, the processing unit 3 starts a process for adjusting the exposure amount. This instruction input is performed in a state where the fluorescent lamp 22 is turned on at a predetermined position and the light diffusion sheet 100 is set.
First, the processing unit 3 inputs an imaging signal of the line sensor camera 1, and the signal level is within a predetermined range, exceeds an upper limit within the predetermined range, or does not reach a lower limit within the predetermined range. Or is determined. The operation of the processing unit 3 branches depending on the determination.
When the signal level is within the predetermined range, the processing unit 3 ends the adjustment of the exposure amount.
When the signal level exceeds the upper limit within a predetermined range, the processing unit 3 performs adjustment to reduce the exposure amount.
When the signal level does not reach the lower limit within the predetermined range, the processing unit 3 performs adjustment to increase the exposure amount.
In the process of increasing / decreasing the exposure amount, the processing unit 3 outputs a command to the control unit 4 to operate the light quantity of the fluorescent lamp 22 in the illumination unit 2, the analog gain of the line sensor camera 1, the lens diaphragm, and the like. Is done.

The control unit 4 calculates an operation signal (operation amount) for operating the fluorescent lamp moving means 23 with the predetermined position derived by the processing unit 3 as a target position. The fluorescent lamp moving means 23 inputs the operation signal and stops moving the fluorescent lamp 22 to a predetermined position.
Based on the output from the processing unit 3, the control unit 4 calculates operation signals such as the light quantity of the fluorescent lamp 22 in the illumination unit 2, the analog gain of the line sensor camera 1, and the lens aperture (described later).
Further, the control unit 4 calculates an operation signal for the transport unit 5 based on the output from the processing unit 3. For example, the operator inputs to the processing unit 3 an instruction to start and stop the conveyance in the conveyance unit 5 and the conveyance speed. The instruction signal is output from the processing unit 3, and the control unit 4 calculates an operation signal of the transport unit 5 based on the instruction signal.

The conveyance means 5 includes a PLC 51 and a conveyance means 52 as shown in FIG. The control by the control unit 4 of the transport unit 5 as described above is performed directly on the PLC 51, and the transport unit 52 is indirectly controlled via the PLC 51.
The conveying unit 5 is a conveying unit that conveys the light diffusion sheet 100 to be inspected. Conveyance means 5 performs conveyance for sub-scanning with respect to the main scanning in the imaging of the line sensor camera 1. Accordingly, the transport direction is substantially perpendicular to the main scanning direction.
The conveying means 5 has an unwinding part and a winding part, as shown in FIG. Further, it is possible to provide a well-known configuration for supplying the web from the winding body, discharging the web after performing inspection and processing, winding the web, and forming the winding body again. For example, an infeed unit, an outfeed unit, a tension controller, and the like can be provided. The present invention is not limited by the configuration of the transport system.

  The server 6 provides data related to the inspection item to the processing unit 3 of the inspection apparatus. That is, a product name, a manufacturing number, the number of wound bodies, the web length of each wound body, the optical characteristics (haze value) of the light diffusion sheet 100, a table, an inspection standard (allowable range), and the like are provided. Also, inspection result data is input from the inspection device and stored as quality control data.

  Next, the operation of the inspection apparatus according to the present invention will be described. Here, the operation for adjusting the exposure amount will be described with reference to FIGS. FIG. 5 is a diagram showing a process of increasing the exposure amount (inspection light amount). FIG. 6 is a diagram showing a process of reducing the exposure amount (inspection light amount). FIG. 7 is a diagram showing the process of adjusting the lens aperture in units of one scale. FIG. 8 is a diagram showing the process when the exposure amount is adjusted by changing the line rate of the line sensor camera 1.

  A process for increasing the exposure amount (inspection light amount) will be described with reference to FIG. The example shown in FIG. 5 considers priorities for factors that increase the amount of inspection light. The three operations of increasing the light amount of the light source, increasing the analog gain of the line sensor camera, and opening the aperture are the operations for increasing the inspection light amount, but these three operations have respective disadvantages. (1) The light amount UP of the light source decreases the lamp life. (2) The analog gain UP of the line sensor camera increases noise. (3) Opening the aperture causes a decrease in the amount of light and blurring in the periphery of the visual field. Since (1) does not affect the inspection performance, it can be increased to the extent that the lifetime is not significantly reduced (for example, the rated voltage is the upper limit for halogen lamps). (2) can be increased to the extent that noise does not affect the inspection performance. The effect of (3) increases as the aperture is opened. In addition, the stop is often a stepwise adjustment unit with an F-number as a geometric series, and fine adjustment of the amount of light is difficult. Further, frequent movement of the aperture tends to lead to failure of the apparatus as compared with frequent movement of (1) and (2). Considering the above, it is preferable to increase the inspection light amount by the following procedure.

First, in step S101 (light source light amount UP) in FIG. 5, the processing unit 3 outputs a command to increase the light source light amount to the control unit 4. The control unit 4 performs an operation of increasing the supply power to the high-frequency lighting power source 21 of the illumination unit 2.
Next, in step S102 (inspection light amount confirmation), the processing unit 3 reads an imaging signal output from the line sensor camera 1. When the signal level is within a predetermined range, the processing unit 3 ends the adjustment of the exposure amount. When the signal level does not reach the lower limit within the predetermined range, the processing unit 3 proceeds to step S103.
Next, when the light source setting has not reached the upper limit in step S103 (the light source setting is the upper limit?), The processing unit 3 returns to step S101 and repeats the subsequent steps. On the other hand, when the light source setting has reached the upper limit, the process proceeds to step S104.

Next, in step S104 (line sensor analog gain UP), the processing unit 3 outputs a command to increase the analog gain to the control unit 4. The control unit 4 performs an operation of increasing the analog gain for the analog amplifier of the drive unit 12 of the line sensor camera 1.
Next, in step S105 (inspection light amount confirmation), the processing unit 3 reads an imaging signal output from the line sensor camera 1. When the signal level is within a predetermined range, the processing unit 3 ends the adjustment of the exposure amount. When the signal level does not reach the lower limit within the predetermined range, the processing unit 3 proceeds to step S106.
Next, in step S106 (the light source setting is the upper limit?), When the analog gain has not reached the upper limit, the processing unit 3 returns to step S104 and repeats the subsequent steps. On the other hand, when the analog gain has reached the upper limit, the process proceeds to step S107.

Next, in step S107 (the lens aperture is opened by one scale), the processing unit 3 outputs a command for opening the lens aperture by one scale to the control unit 4. The control unit 4 performs an operation of opening the lens aperture on the lens unit 13 of the line sensor camera 1 by one scale.
Next, in step S <b> 108 (inspection light amount confirmation), the processing unit 3 reads an imaging signal output from the line sensor camera 1. When the signal level is within a predetermined range, the processing unit 3 ends the adjustment of the exposure amount. When the signal level does not reach the lower limit within the predetermined range, the processing unit 3 returns to step S107 and repeats the subsequent steps. When the signal level exceeds the upper limit within the predetermined range, the processing unit 3 proceeds to step S109.

Next, in step S109 (the analog gain is set to the lowest value), the processing unit 3 outputs a command for setting the analog gain to the lowest value to the control unit 4. The control unit 4 performs an operation of setting the analog gain to the minimum value with respect to the analog amplifier of the drive unit 12 of the line sensor camera 1.
Next, in step S110 (line sensor analog gain UP), the processing unit 3 outputs a command to increase the analog gain to the control unit 4. The control unit 4 performs an operation of increasing the analog gain for the analog amplifier of the drive unit 12 of the line sensor camera 1.
Next, in step S111 (inspection light amount confirmation), the processing unit 3 reads an imaging signal output from the line sensor camera 1. When the signal level is within a predetermined range, the processing unit 3 ends the adjustment of the exposure amount. When the signal level does not reach the lower limit within the predetermined range, the processing unit 3 returns to step S110 and repeats the subsequent steps.

Next, a process for reducing the exposure amount (inspection light amount) will be described with reference to FIG. The example shown in FIG. 6 considers the order of priority for factors that reduce the inspection light quantity. The concept of the priority order is the same as the process for increasing the exposure amount (inspection light amount) described above (FIG. 5).
Note that the example shown in FIG. 6 starts with a step of reducing the analog gain. This is because the difference between the light amount at the start of setting and the appropriate value of the inspection light amount is smaller than the change amount of one scale of the lens diaphragm. In order to cope with the case, there is no change in that priority is given to the diaphragm when the amount of inspection light is reduced.

First, in step S201 in FIG. 6 (line sensor analog gain DOWN), the processing unit 3 outputs a command for decreasing the analog gain to the control unit 4. The control unit 4 performs an operation of reducing the analog gain with respect to the analog amplifier of the driving unit 12 of the line sensor camera 1.
Next, in step S202 (inspection light amount confirmation), the processing unit 3 reads an imaging signal output from the line sensor camera 1. When the signal level is within a predetermined range, the processing unit 3 ends the adjustment of the exposure amount. When the signal level is not lowered to the upper limit within the predetermined range (excessive), the processing unit 3 proceeds to step S203.
Next, in step S203 (the light source setting is the lower limit?), When the analog gain has not reached the lower limit, the processing unit 3 returns to step S201 and repeats the subsequent steps. On the other hand, when the analog gain has reached the lower limit, the process proceeds to step S204.

Next, in step S204 (the lens aperture is reduced by one scale), the processing unit 3 outputs a command for reducing the lens aperture by one scale to the control unit 4. The control unit 4 performs an operation for reducing the aperture of the lens by one scale with respect to the lens unit 13 of the line sensor camera 1.
Next, in step S205 (inspection light amount confirmation), the processing unit 3 reads an imaging signal output from the line sensor camera 1. When the signal level is within a predetermined range, the processing unit 3 ends the adjustment of the exposure amount. When the signal level does not reach the lower limit within the predetermined range, the processing unit 3 proceeds to step S206. When the signal level is not lowered to the upper limit within the predetermined range (excessive), the processing unit 3 proceeds to step S208. When the signal level does not reach the lower limit within the predetermined range (insufficient), the processing unit 3 proceeds to step S206.

Next, in step S206 (line sensor analog gain UP), the processing unit 3 outputs a command to increase the analog gain to the control unit 4. The control unit 4 performs an operation of increasing the analog gain for the analog amplifier of the drive unit 12 of the line sensor camera 1.
Next, in step S207 (inspection light amount confirmation), the processing unit 3 reads an imaging signal output from the line sensor camera 1. When the signal level is within a predetermined range, the processing unit 3 ends the adjustment of the exposure amount. When the signal level does not reach the lower limit within the predetermined range, the processing unit 3 returns to step S206 and repeats the subsequent steps.

Next, in step S208 (F value lower limit?), When the F value is not the lower limit, the processing unit returns to step S204 and repeats the subsequent steps. When the F value is the lower limit, the process proceeds to step S209.
Next, in step S209 (light source light amount DOWN), the processing unit 3 outputs a command for reducing the light source light amount to the control unit 4. The control unit 4 performs an operation for reducing the supply power to the high-frequency lighting power source 21 of the illumination unit 2.
Next, in step S210 (inspection light amount confirmation), the processing unit 3 reads an imaging signal output from the line sensor camera 1. When the signal level is within a predetermined range, the processing unit 3 ends the adjustment of the exposure amount. When the signal level is not lowered to the upper limit within the predetermined range, the processing unit 3 returns to step S209 and repeats the subsequent steps.

  The adjustment for changing the exposure amount (inspection light amount) when the diaphragm in the lens unit 13 of the line sensor camera 1 is a stepwise adjustment unit that takes the F series as a geometric series will be described with reference to FIG. When the inspection light quantity is increased, adjustment is performed by replacing step S107 and subsequent steps in FIG. 5 with step S117 and subsequent steps in FIG. In step S119 in FIG. 7, the UP amount when the analog gain of the line sensor camera 1 is increased is set to a value obtained by dividing the UP amount by the square root of the F value change amount per aperture scale. For example, when a lens whose scale is engraved with an F value and a square root of 2 is used, the analog gain UP amount is halved. The same applies when the inspection light amount is DOWN and when the inspection light amount is increased, and the UP amount when the analog gain of the line sensor camera 1 is increased or the DOWN amount when the DOWN is performed per one aperture scale of the lens unit 13. Set to the value divided by the square root of the F value variation. In the step shown in FIG. 5, the analog gain is once lowered to the minimum value and then raised to an appropriate value, whereas in the step shown in FIG. 7, the exposure amount (inspection light amount) of the previous stop is set. Since only the corresponding analog gain can be lowered, the setting time can be shortened.

First, in step S117 in FIG. 7 (the lens aperture is opened by one scale), the processing unit 3 outputs a command for opening the lens aperture by one scale to the control unit 4. The control unit 4 performs an operation of opening the lens aperture on the lens unit 13 of the line sensor camera 1 by one scale.
Next, in step S118 (inspection light amount confirmation), the processing unit 3 reads an imaging signal output from the line sensor camera 1. When the signal level is within a predetermined range, the processing unit 3 ends the adjustment of the exposure amount. When the signal level does not reach the lower limit within the predetermined range, the processing unit 3 returns to step S107 and repeats the subsequent steps. When the signal level exceeds the upper limit within the predetermined range, the processing unit 3 proceeds to step S109.

Next, in step S119 (the analog gain is set to a value obtained by dividing the analog gain by the square root of the F value change amount per scale), the processing unit 3 sets the analog gain to the control unit 4 and changes the F value per scale value. Outputs a command that sets the value divided by the square root of the quantity. The control unit 4 performs an operation of setting the analog gain to the minimum value with respect to the analog amplifier of the drive unit 12 of the line sensor camera 1.
Next, in step S120 (line sensor analog gain UP), the processing unit 3 outputs a command to increase the analog gain to the control unit 4. The control unit 4 performs an operation of increasing the analog gain for the analog amplifier of the drive unit 12 of the line sensor camera 1.
Next, in step S121 (inspection light amount confirmation), the processing unit 3 reads an imaging signal output from the line sensor camera 1. When the signal level is within a predetermined range, the processing unit 3 ends the adjustment of the exposure amount. When the signal level does not reach the lower limit within the predetermined range, the processing unit 3 returns to Step S120 and repeats the subsequent steps.

A process for adjusting the exposure amount (inspection light amount) by adjusting the line rate of the line sensor camera 1 will be described with reference to FIG. The line rate is a main scanning frequency in the line sensor camera 1. The line rate is related to the exposure time, that is, the charge accumulation time. The exposure time is increased by lowering the main scanning frequency (lengthening the cycle) and increasing the main scanning frequency (shortening the cycle). Time can be shortened.
The process shown in FIG. 8 is a process performed in the previous step of FIG. 5 showing the process of increasing the exposure amount (inspection light amount), and step S101 in FIG. 5 and step S4 in FIG. 8 are the same. .

First, in step S <b> 1 of FIG. 8, the processing unit 3 outputs a command for increasing the exposure time of the line sensor camera 1 to the control unit 4. The control unit 4 performs an operation for increasing the exposure time on the drive unit 12 of the line sensor camera 1 of the illumination unit 2.
Next, in step S <b> 2 (inspection light amount confirmation), the processing unit 3 reads an imaging signal output from the line sensor camera 1. When the signal level is within a predetermined range, the processing unit 3 ends the adjustment of the exposure amount. When the signal level does not reach the lower limit within the predetermined range, the processing unit 3 proceeds to step S3.
Next, when the light source setting has not reached the upper limit in step S3 (exposure time is upper limit?), The processing unit 3 returns to step S1 and repeats the subsequent steps. On the other hand, when the light source setting has reached the upper limit, the process proceeds to step S4, that is, the process proceeds to step S101 in FIG.

The operation for adjusting the exposure amount has been described above. Next, an example of operation | movement at the time of test | inspecting in the test | inspection apparatus of this invention is demonstrated with reference to FIG. It is assumed that the light source position adjustment and the exposure amount adjustment have been completed.
First, in step S301 (production start) in FIG. 9, production of the light diffusion sheet 100 is started in the production machine. The inspection device is provided after the unwinding part and before the winding part in the production machine. Usually, it is provided immediately before the winding unit.

Next, in step S302 (image input), the line sensor camera 1 of the inspection apparatus images the light diffusion sheet 100 and outputs an imaging signal. The processing unit 3 inputs the signal and stores it in the memory as a captured image.
Next, in step S303 (whether or not a defect has occurred), the processing unit 3 has defects in optical characteristics of the light diffusion sheet 100 and defects in appearance such as foreign matter, scratches, and dirt based on the stored captured image. A process of inspecting whether or not there is is performed. This process includes a process of extracting a defect from a captured image, a process of determining whether or not the extracted defect is within an allowable range, and the like. That is, as a result of the determination, if there is no defect, the process proceeds to step S304. As a result of the determination, if a defect exists, the process proceeds to step S305.

Next, in step S304 (continuation of production), the processing unit 3 performs processing for continuing production. That is, returning to step S302, the above-described process is repeated.
Next, in step S305 (line stop), the processing unit 3 performs a process of stopping the production line and warning the operator.

It is a figure which shows the imaging system and conveyance system in the inspection apparatus of this invention as a schematic diagram. It is a figure which shows the modification of the imaging system in the test | inspection apparatus of this invention as a schematic diagram. It is a figure which shows the whole structure in the test | inspection apparatus of this invention as a pictorial diagram. It is a figure which shows the whole structure structure in the test | inspection apparatus of this invention as a block diagram. It is a figure which shows the process of increasing the exposure amount (inspection light quantity) in the inspection apparatus of this invention. It is a figure which shows the process of the process which reduces the exposure amount (inspection light quantity) in the inspection apparatus of this invention. It is a figure which shows the process of a process when adjusting the aperture_diaphragm | restriction of a lens in 1 unit | scale in the inspection apparatus of this invention. It is a figure which shows the process of processing, when adjusting the exposure amount by changing the line rate of the line sensor camera in the inspection apparatus of this invention. It is a figure shown about an example of operation | movement when inspecting in the inspection apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Line sensor camera 11 Line sensor element 12 Drive circuit 13 Lens aperture 2 Illumination part 21 High frequency lighting power supply 22 Fluorescent lamp 23 Fluorescent lamp moving means 3 Processing part 4 Control part 5 Conveyance part 51 PLC
52 Conveying means 6 Server 100 Light diffusion sheet

Claims (5)

An inspection apparatus for inspecting the presence or absence of defects in the transported light diffusion sheet, comprising a line sensor camera, a line light source, and a light source position adjusting means,
The line sensor camera images the light diffusion sheet by scanning in a direction perpendicular to the transfer direction of the light diffusion sheet,
The line-shaped light source is provided so as to be able to stop moving to a position on the non-imaging side of the light diffusion sheet, and transmits and illuminates the imaging region of the line sensor camera in the light diffusion sheet,
The light source position adjusting means performs position adjustment for stopping the movement of the linear light source to a predetermined position determined by light diffusion characteristics in the light diffusion sheet;
Inspection apparatus characterized by that. 2. The inspection apparatus according to claim 1, wherein the predetermined position is a position where the linear light source is further away from the optical axis of the line sensor camera as the degree of light diffusion of the light diffusion sheet is larger, and the light diffusion of the light diffusion sheet. The inspection apparatus characterized in that the smaller the degree, the closer to the optical axis of the line sensor camera the linear light source. The inspection apparatus according to claim 1 or 2, wherein a moving direction when the movement is stopped is parallel to a traveling direction of the light diffusion sheet. 4. The inspection apparatus according to claim 1, further comprising an exposure amount adjusting unit that automatically adjusts an exposure amount to an appropriate value after the position adjustment, and the exposure amount adjusting unit is an operation for increasing the exposure amount. The priority of the operation is the light amount of the light source, the analog gain of the line sensor camera, the aperture of the imaging lens of the line sensor camera, the line rate of the line sensor camera, and the priority of the operation in the operation of decreasing the exposure amount. An inspection apparatus characterized by operating at least one of the line rate, the diaphragm, the analog gain, and the light amount. The inspection apparatus according to any one of claims 1 to 4, further comprising a data processing unit, wherein the data processing unit performs at least a process for detecting a foreign matter defect in the light diffusion sheet and a process for detecting a light diffusion defect. An inspection apparatus which outputs a detection result so that a defect content can be understood.

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