JP2019117104A - Inspection system - Google Patents

Abstract

To implement inspection which uses a plurality of illumination methods in a simpler configuration.SOLUTION: The inspection system inspects a sheet-like object being conveyed by a driving device in a first direction. The inspection system includes a plurality of light sources, a linear image sensor, and a control circuit. The light sources are arranged to illuminate the same portion of the object when the object is stationary. The linear image sensor includes a plurality of light detection cells arranged in a second direction crossing the first direction. The linear image sensor images the portion of the object irradiated with the light at a constant interval. The control circuit controls the plurality of light sources. In the state in which the driving device is conveying the object, the control circuit sequentially lights up the plurality of light sources in synchronization with the timing of imaging by the linear image sensor.SELECTED DRAWING: Figure 10

Description

  The present application relates to an inspection apparatus.

  Various methods are known for inspecting a sheet-like object such as film or paper for abnormalities such as foreign matter or defects.

  For example, Patent Document 1 discloses an inspection apparatus which inspects a defect of an inspection object by imaging the surface of a sheet-like inspection object. The inspection apparatus of Patent Document 1 includes a linear imaging device and a linear illumination device having a plurality of light emitting regions arranged in a direction along a cell row of the linear imaging device. Lighting of the plurality of light emitting areas is performed for each data transfer operation of the linear imaging element. The inspection apparatus inspects the defect of the inspection object based on the plurality of images generated by the linear imaging device.

  Patent Document 2 discloses an inspection apparatus provided with two front side light sources for irradiating light from the front side to a sheet to be inspected, one back side light source for irradiating light from the back side, and a camera. The camera acquires a bright field image of the inspection area in a state in which the two front light sources emit light, and acquires a dark field image of the inspection area in a state in which the back light source emits light. Whether to obtain a bright-field image or a dark-field image depends on the nature of the sheet, and one or both suitable for inspection is selected.

JP, 2014-163771, A JP 2000-108316 A

  The present disclosure provides a technique for realizing inspection with a plurality of illumination methods with a simpler configuration.

  An inspection apparatus according to an aspect of the present disclosure inspects a sheet-like object conveyed in a first direction by a drive device. The inspection apparatus is configured to, when the object is stationary, include a plurality of light sources arranged to irradiate the same part of the object with light, and a second direction intersecting the first direction. A linear image sensor including a plurality of light detection cells arranged in a row, the linear image sensor capturing an image of a portion of the object irradiated with the light at predetermined intervals, and a control circuit controlling the plurality of light sources A control circuit that sequentially turns on the plurality of light sources in synchronization with the timing of imaging by the linear image sensor in a state in which the driving device is transporting the object.

  The general or specific aspects of the present disclosure may be embodied in an apparatus, a system, a method, an integrated circuit, a computer program, or a storage medium. Alternatively, the present invention may be realized as any combination of an apparatus, a system, a method, an integrated circuit, a computer program, and a storage medium.

  According to the technology of the present disclosure, it is possible to perform inspection by a plurality of illumination methods with a simpler configuration.

FIG. 1 is a diagram showing an example of a method of inspecting an object using a light source and a camera. FIG. 2 is a diagram showing an example of a system for inspecting a sheet-like object using a plurality of illumination methods. FIG. 3 is a schematic view showing the overall configuration of an inspection system in an exemplary embodiment of the present disclosure. FIG. 4 is a view schematically showing the configuration of the inspection apparatus. FIG. 5 is a view schematically showing a state of imaging by a camera. FIG. 6 is a cross-sectional view schematically showing the structure of a part of the image sensor in the camera. FIG. 7 is a diagram for explaining the operation of the camera. FIG. 8 is a diagram showing a synchronization signal that determines the imaging timing of the image sensor and the lighting timing of each of the three light sources. FIG. 9 is a diagram for explaining an image generation method in the present embodiment. FIG. 10 is a flowchart showing an example of an operation performed by the inspection apparatus.

  Before describing the embodiments of the present disclosure, the findings found by the present inventors will be described.

  There are various methods of illumination when inspecting an object (also referred to herein as a “test object”) using a camera, depending on the purpose.

  FIG. 1 is a diagram showing a typical example of a method of inspecting an object using a light source and a camera. FIG. 1A shows an example of an inspection method using epi-illumination. FIG. 1 (b) shows an example of the inspection method by oblique light illumination. FIG. 1C shows an example of the inspection method using transmitted illumination. Arrows in FIG. 1 exemplarily indicate light rays.

  In the method by the epi-illumination shown in FIG. 1A, the light source 200 causes light to be incident on the object 300 from the same side as the camera 100 as viewed from the object 300. For that purpose, an optical member 400 such as a half mirror or a beam splitter is used. This method is suitable for use in observing conditions such as reflectance or color on the surface of a planar object mainly.

  In the oblique illumination method shown in FIG. 1B, the light source 200 causes light to be incident on the object 300 obliquely with respect to the straight line connecting the camera 100 and the object 300. This method is suitable mainly for use in observing a fine structure such as unevenness on the surface of an object.

  In the transmission illumination method shown in FIG. 1C, the light source 200 causes light to be incident on the object 300 from the side opposite to the side of the camera 100 as viewed from the object 300. The camera 100 acquires an image of light transmitted through the object 300. This method is suitable mainly for the purpose of observing the transmittance of a specimen or the state of the back surface of the specimen.

  When the inspection by such a plurality of illumination methods is performed on the same portion of the sheet-like object, the following configuration can be considered.

  FIG. 2 is a diagram showing an example of a system for inspecting a sheet-like object using a plurality of illumination methods. In this example, the inspection object is a sheet-like product such as roll paper or film. The inspection object is transported in one direction by the drive device. The product is cut to an appropriate size after undergoing the manufacturing process and the inspection process.

  In the manufacturing process, printing or processing on a roll paper or a film which is a raw material is performed. In the subsequent inspection process, the product is inspected by a plurality of illumination methods. For example, an inspection of the state of characters, patterns or colors on the surface by epi-illumination, an inspection of irregularities by oblique illumination, an inspection of the state of the back surface by transmissive illumination, etc. are sequentially performed. By these inspections, abnormalities such as printing defects, inclusion of foreign matter, or scratches can be detected.

  In a system in which inspections using such a plurality of illumination methods are performed, a plurality of cameras are prepared for each inspection, and divided into a plurality of steps to be photographed. This increases the space required to perform the entire test. In addition, the system is relatively complex, and it takes time to adjust or maintain the device. As a result, the cost of the system tends to increase.

  When the test object is stationary, a method is possible in which a plurality of lighting devices are attached to one camera and shooting is performed each time while switching the lighting device to be lit. However, when the sheet-like product is inspected while being transported, such a method can not be applied because the test object does not stand still.

  Therefore, the present inventors examined an inspection method that enables inspection with a plurality of illumination methods with a simpler configuration. As a result, it has been found that the above problem can be solved by the configuration described below.

  An inspection apparatus according to an embodiment of the present disclosure inspects a sheet-like object conveyed in a first direction by a drive device. The inspection apparatus is configured to, when the object is stationary, include a plurality of light sources arranged to irradiate the same part of the object with light, and a second direction intersecting the first direction. And a control circuit that controls the plurality of light sources. The linear image sensor images a portion of the object irradiated with the light at regular intervals. The control circuit sequentially turns on the plurality of light sources in synchronization with timing of imaging by the linear image sensor in a state where the drive device is transporting the object.

  According to such a configuration, it is possible to image an object with the linear image sensor each time while turning on a plurality of light sources, for example, one by one at predetermined time intervals. Thereby, a plurality of types of inspections with different illumination methods can be performed in a space-saving manner.

  In one embodiment, the linear image sensor outputs a one-dimensional image signal corresponding to an amount of light detected by the plurality of light detection cells at each predetermined time. The inspection apparatus may further include a signal processing circuit that generates a plurality of two-dimensional image signals based on light from the plurality of light sources from the plurality of one-dimensional image signals output from the linear image sensor.

  Thereby, the plurality of one-dimensional image signals acquired while switching the plurality of light sources can be combined to obtain the plurality of two-dimensional image signals respectively corresponding to the plurality of light sources.

  Hereinafter, exemplary embodiments of the present disclosure will be described. However, more detailed description than necessary may be omitted. For example, detailed description of already well-known matters and redundant description of substantially the same configuration may be omitted. This is to avoid unnecessary redundancy in the following description and to facilitate understanding by those skilled in the art. It is noted that the inventors provide the attached drawings and the following description so that those skilled in the art can fully understand the present disclosure, and intend to limit the claimed subject matter by these. Absent. In the following description, the same or similar components are given the same reference numerals.

(Embodiment)
FIG. 3 is a schematic view showing the overall configuration of an inspection system in an exemplary embodiment of the present disclosure. The inspection system is used, for example, in a production line of a factory. The inspection system includes an inspection device 10 and a drive device 600.

  The driving device 600 transports the sheet-like object 300 in one direction (referred to as “first direction”). The driving device 600 includes a plurality of rollers for conveyance and at least one motor. In the example of FIG. 3, two rollers are disposed at both ends of the object 300. Each of the two rollers is connected to a motor and is rotated by the motor. Thus, the object 300 is transported in the first direction. The driving device 600 may also include other components such as a rotary encoder that detects the movement of the object 300 and a support that supports the object 300.

  The inspection apparatus 10 in the present embodiment includes three light sources and one camera. The three light sources are arranged in a relatively narrow area, and the number of cameras is only one. For this reason, space saving can be achieved as compared with the configuration shown in FIG.

  FIG. 4 is a view schematically showing the configuration of the inspection apparatus 10. As shown in FIG. The inspection apparatus 10 includes three light sources 200A, 200B, and 200C, a camera 100, and a control circuit 500. The camera 100 includes an optical system 110 including at least one lens, an image sensor 120, and a signal processing circuit 130.

  The three light sources 200A, 200B, and 200C are arranged to irradiate the same portion of the object 300 with light when the object 300 is at rest. Here, "the same part" does not have to be exactly the same part, as long as regions irradiated with light from the respective light sources partially overlap. In the present embodiment, the three light sources 200A, 200B, and 200C are sequentially turned on and are not simultaneously turned on. However, if they are simultaneously turned on, the luminous flux from each of the three light sources 200A, 200B and 200C has overlapping portions on the object 300.

  The first light source 200A and the second light source 200B allow light to be incident on the object 300 from the side of the image sensor 120 as viewed from the object 300. On the other hand, the third light source 200C causes light to be incident on the object 300 from the opposite side to the side of the image sensor 120 as viewed from the object 300.

  More specifically, the first light source 200A causes light to vertically enter the object 300 from the same side as the image sensor 120. That is, the first light source 200A illuminates the object 300 by the method of epi-illumination. For this reason, an optical member 400 such as a half mirror or a beam splitter is disposed on the path of light from the first light source 200A. The light emitted from the first light source 200 </ b> A is reflected by the optical member 400 and enters a part of the object 300. The reflected light passes through the optical member 400 and enters the camera 100 through the optical system 110.

  The second light source 200 B causes light to obliquely enter the object 300 from the same side as the image sensor 120. That is, the angle between the central axis of the light beam emitted from the second light source 200B and the normal direction of the plane when the surface of the object 300 is approximated by the plane is larger than 0 ° and smaller than 90 °. . This angle is set to an appropriate value according to the purpose of inspection. The light emitted from the second light source 200 </ b> B is reflected by the object 300, passes through the optical member 400, and is incident on the camera 100.

  The third light source 200 </ b> C causes light to vertically enter the object 300 from the opposite side of the image sensor 120. That is, the third light source 200C illuminates the object 300 by the method of transmission illumination. The light emitted from the third light source 200 </ b> C passes through the object 300, passes through the optical member 400, and enters the camera 100.

  The light incident on the camera 100 is focused by the optical system 110 and is incident on the imaging surface of the image sensor 120. The image sensor 120 is a linear image sensor (also referred to as a “line sensor”), and repeatedly generates a one-dimensional image signal based on incident light at fixed time intervals. The generated image signal is sent to the signal processing circuit 130. The signal processing circuit 130 generates a two-dimensional image signal from a plurality of one-dimensional image signals.

  FIG. 5 is a view schematically showing a state of imaging by the camera 100. As shown in FIG. The camera 100 captures a linear region that intersects (typically, is orthogonal to) the transport direction of the object 300. In a state in which the object 300 is transported at a constant speed, the camera 100 captures an image of the object 300 at regular intervals.

  FIG. 6 is a cross-sectional view schematically showing the structure of a part of the image sensor 120 in the camera 100. As shown in FIG. The image sensor 120 includes a semiconductor substrate 121, and a plurality of light detection cells 122a, 122b, 122c,... Arranged one-dimensionally on the surface of the semiconductor substrate 121. A wiring layer 125 is formed on the surface of the semiconductor substrate 121. The wiring layer 125 connects the light detection cells 122a, 122b, 122c,... To a drive circuit (not shown). The image sensor 120 further includes an array 123 of a plurality of microlenses that condenses on the light detection cells 122a, 122b, 122c,. The light detection cells 122a, 122b, 122c,... Are arranged in a second direction that intersects the transport direction (first direction) of the object 300. Each light detection cell includes, for example, a photoelectric conversion element such as a photodiode. Each light detection cell generates a signal charge according to the amount of incident light. The charge accumulated in each of the light detection cells is read at regular time intervals and sent to the signal processing circuit 130 as a one-dimensional image signal. With such a structure, the image sensor 120 captures an image of a portion of the object 300 irradiated with light at regular intervals.

  The image sensor 120 is not limited to the configuration shown in FIG. 6, and any linear image sensor can be used. The linear image sensor may be, for example, a COMS type or a CCD type.

  FIG. 7 is a diagram for explaining the operation of the camera 100. The camera 100 in the present embodiment is a line sensor camera provided with a linear image sensor. In a line sensor camera, since a plurality of light detection cells are arranged in a one-dimensional manner, only one-dimensional image can be obtained at one time. However, by moving the camera 100 and the object 300 relative to each other as in the present embodiment, a two-dimensional image can be generated.

  As shown in FIG. 7, in a state where the object 300 is moving, the image sensor 120 of the camera 100 captures an image of the object 300 at regular intervals. At this time, the image sensor 120 repeats imaging in minute movement units of the object 300. The image sensor 120 generates a one-dimensional image signal (hereinafter also referred to as a “line signal”) for each photographing and records it in the memory. This operation generates a large number of one-dimensional images. A two-dimensional image can be generated by reading out and reconstructing the images of a plurality of lines recorded in the memory.

  In the present embodiment, photographing by a plurality of illumination methods is realized by one camera 100. The control circuit 500 sequentially switches lighting of the light sources 200A, 200B, and 200C in synchronization with the timing of imaging by the image sensor 120. Here, switching of lighting of each light source may be performed for each imaging performed by the image sensor 120, or may be performed for each of a plurality of imagings. This makes it possible to obtain images with different illumination methods for each row or for each row.

  FIG. 8 is a diagram showing an example of the synchronization signal that determines the imaging timing of the image sensor 120 and the lighting timing of each of the three light sources 200A, 200B, and 200C. The synchronization signal may be input to the image sensor 120 from, for example, a control circuit disposed inside or outside the camera 100. The synchronization signal may be input from a rotary encoder provided in the drive device 600. Alternatively, the control circuit 500 may generate a synchronization signal and input it to the image sensor 120. As illustrated, the synchronization signal is input to the image sensor 120 at regular intervals. The period of the synchronization signal is appropriately determined in accordance with the required resolution. The period of the synchronization signal may be, for example, several microseconds to several milliseconds.

  The control circuit 500 monitors the synchronization signal from the camera 100, and repeats the operation of lighting the light sources 200A, 200B, and 200C one by one in order according to the timing of the synchronization signal. In this example, n is an integer of 0 or more, and the control circuit 500 turns on only the first light source 200A and turns off the other light sources 200B and 200C at the 3n + 1-th shooting. At the (3n + 2) th shooting, the control circuit 500 turns on only the second light source 200B and turns off the other light sources 200A and 200C. At the 3n + 3rd shooting, the control circuit 500 turns on only the third light source 200C and turns off the other light sources 200A and 200B.

  By such control, imaging with light from the light source 200A, imaging with light from the light source 200B, and imaging with light from the light source 200C are repeated.

  FIG. 9 is a diagram for explaining an image generation method in the present embodiment. FIG. 9A shows an example of a two-dimensional image obtained when shooting is performed using the first light source 200A. FIG. 9B shows an example of a two-dimensional image obtained when shooting is performed using the second light source 200B. FIG. 9C shows an example of a two-dimensional image obtained when shooting is performed using the third light source 200C. Note that the illustrated image is an example, and is simplified as compared to the image actually obtained for the sake of clarity.

  In the present embodiment, the first light source 200A (epi-illumination) is turned on at the first, fourth, seventh,... During the second, fifth, eighth,... Shooting, the second light source 200B (shielded illumination) is turned on. At the third, sixth, ninth, and so on, the third light source 200C (transmission illumination) is turned on. The image sensor 120 generates and outputs a one-dimensional image signal for each photographing. Each of the plurality of one-dimensional image signals to be output corresponds to one row of signals in the two-dimensional image generated by the signal processing circuit 130 later. That is, assuming that n is an integer of 0 or more, the image signal in the 3n + 1'th row represents a one-dimensional image based on light from the first light source 200A. The image signal on the 3n + 2'th line represents a one-dimensional image based on the light from the second light source 200B. The image signal in the 3n + 3 line represents a one-dimensional image based on the light from the third light source 200C. FIG. 9D shows an example of an image obtained by combining one-dimensional image signals of a predetermined number of rows.

  The signal processing circuit 130 generates three two-dimensional image signals from those signals recorded in the memory when the imaging of one-dimensional image signals of a predetermined number of rows (for example, several tens of lines to several tens of thousands of lines) is completed. Do. The signal processing circuit 130 generates a two-dimensional image signal by the first light source 200A from the signals on the first, fourth, seventh,. Similarly, the signal processing circuit 130 generates a two-dimensional image signal by the second light source 200B from the signals on the second, fifth, eighth,. The signal processing circuit 130 generates a two-dimensional image signal by the third light source 200C from the signals in the third, sixth, ninth,... Various examinations can be performed based on these two-dimensional images.

The resolution of the camera 100 is determined from the scan speed for each illumination of the camera 100 and the transport speed of the object 300. The resolution is expressed by the number of lines per unit length. The scan speed for each illumination is represented by the number of times of imaging using the illumination per unit time. The transport speed is a moving distance per unit time. The resolution is represented by the following equation.
Resolution (line / mm) = scan speed (line / second) / transport speed (mm / second)

  The scan speed of the camera 100 is inversely proportional to the number of light sources. When three types of illumination are used as in the present embodiment, the scanning speed is 1/3 compared to when one type of illumination is used. In order to maintain high resolution, high scan speed cameras are used.

  As the camera scanning speed increases, so does the lighting switching speed. Each light source may be a fast switchable light source, such as a light emitting diode (LED). Each light source may be a light source other than an LED. For example, a light source in which a laser diode (LD) and a diffusion plate are combined or a light source using an organic light emitting element may be used. Depending on the application, fluorescent or incandescent bulbs may be used. However, since fluorescent lamps and incandescent lamps require time to blink, high-speed switching can not be performed. However, due to the characteristics of the light source, it may be desirable to use these lights. In that case, it can respond, for example by providing a mechanical or liquid-crystal-type shutter between an illuminating device and a to-be-tested object. That is, high speed blinking can be realized by controlling the opening and closing of the shutter at high speed while the light source with the slow response speed is turned on. As such, the light source is not limited to a specific type, and any light source can be used.

  The wavelength and intensity of light emitted from each light source can be arbitrarily set depending on the application. It is not necessary for all of the plurality of light sources to emit light of the same wavelength range. In the present embodiment, three light sources 200A, 200B, 200C are used, but this is merely an example. Depending on the application, two or more light sources may be used. For example, the inspection may be performed using only any two of the light sources 200A, 200B, and 200C described above. Further, all of the plurality of light sources may not be disposed at different positions in different postures. Multiple light sources arranged at substantially the same position and orientation may be used. Even in that case, a plurality of inspections can be performed by changing the wavelength or the intensity.

  The image sensor 120 may be, for example, a contact image sensor. The contact image sensor performs imaging at a close distance so as to substantially contact the object 300. The contact image sensor has features such as a small working distance and not requiring a large lens. For this reason, there are advantages to using a contact image sensor depending on the application. When the contact image sensor is used, the plurality of light sources described above may be provided in the housing of the contact image sensor.

  The image sensor can be used similarly to a general linear image sensor (line sensor) or a contact image sensor. However, in the contact image sensor, the arrangement of the light source may be limited because the working distance is small. There is no problem if a linear image sensor with a large working distance can be used, but there are also cases where the contact image sensor has to be used due to space problems. In such a case, it is possible to cope with the arrangement of the optical system or the device of the image processing logic.

  Next, an example of the operation of the inspection apparatus 10 in the present embodiment will be described.

  FIG. 10 is a flowchart showing an example of an operation performed by the inspection apparatus 10. The inspection apparatus 10 executes, for example, an operation shown in FIG. This operation may be realized by a processor in control circuit 500 executing a computer program. The control circuit 500 includes, for example, a processor and a recording medium such as a memory. The computer program may be stored on a storage medium and executed by a processor.

  The operation of each step will be described below.

  Step S101: The control circuit 500 causes the image sensor 120 to capture an image in a state in which the first light source 200A is turned on and the other light sources 200B and 200C are turned off. The image sensor 120 records one row of one-dimensional image signals (line signals) acquired by imaging on a recording medium such as a memory.

  Step S102: When a predetermined time has elapsed from the start of step S101, the control circuit 500 causes the second light source 200B to turn on and causes the image sensor 120 to capture an image while the other light sources 200A and 200C are turned off. The image sensor 120 records the line signal of the next line acquired by imaging on a recording medium.

  Step S103: When a predetermined time has elapsed from the start of step S102, the control circuit 500 turns on the third light source 200C and causes the image sensor 120 to capture an image in a state in which the other light sources 200A and 200B are turned off. The image sensor 120 records the line signal of the next line acquired by imaging on a recording medium.

  Step S104: The control circuit 500 determines whether recording of a predetermined number of lines is completed. If this determination is No, steps S101 to S104 are executed again. Thereby, imaging using the first to third light sources 200A, 200B, and 200C in order is repeated until recording of a predetermined number of lines is completed. If the determination is Yes, the process proceeds to step S105.

  Step S105: The control circuit 500 determines whether or not there is an instruction to stop shooting. This command may be input to the control circuit 500, for example, due to the operation of a user or administrator of the inspection system. If yes, stop the system operation. In the case of No, the process proceeds to step S106.

  Step S106: The signal processing circuit 130 reads one-dimensional image signals of a predetermined number of lines from the recording medium, and generates three two-dimensional image signals based on those signals. The signal processing circuit 130 extracts line signals of the first line, the fourth line, the seventh line,... And combines them to generate a two-dimensional image signal based on the light from the first light source 200A. The signal processing circuit 130 also extracts the line signals of the second line, the fifth line, the eighth line,... And combines them to generate a two-dimensional image signal based on the light from the second light source 200B. . The signal processing circuit 130 also extracts line signals of the third line, the sixth line, the ninth line,... And combines them to generate a two-dimensional image signal based on light from the third light source 200C. . Note that when generating each two-dimensional image signal, the signal processing circuit 130 may interpolate data of a line in which data is missing as necessary. For example, for the two-dimensional image corresponding to the light source 200A, the data in the second and third lines may be interpolated using the data in the first and fourth lines.

  Step S107: The signal processing circuit 130 determines the presence or absence of abnormality based on each of the three generated two-dimensional images. The signal processing circuit 130 executes, for example, a known image processing algorithm to analyze each two-dimensional image. Thus, for example, the normality of printing, the presence or absence of contamination of foreign matter, the presence or absence of a scratch or stain, etc. are determined. If no abnormality is detected, the process returns to step S101, and the above-described operation is performed again. If an abnormality is detected, the process proceeds to step S108.

  Step S108: When the signal processing circuit 130 detects an abnormality as a result of the image analysis, a flag indicating the abnormality is added to the image signal in which the abnormality is detected, and the image signal is recorded. Then, the control circuit 500 transmits a signal (alert) indicating that an abnormality has been detected. When the control circuit 500 receives an alert, for example, the control circuit 500 sends a notification to a portable terminal or a management device used by a user or a manager. This allows the user or administrator to know that there is an abnormality in the product. Also in this case, the process returns to step S101, and the inspection of the remaining part of the object 300 is continued.

  By the operation as described above, the inspection apparatus 10 can perform inspection by a plurality of illumination methods. In the present embodiment, inspection using a plurality of light sources 200A, 200B, and 200C can be performed with one camera 100. For this reason, desired inspection can be realized with space saving and a simple configuration.

  The above configuration and operation are merely examples, and the technology of the present disclosure is not limited to the above embodiments. An inspection apparatus, an inspection system, and an inspection method, which appropriately modify the above configuration and operation, are also included in the scope of the present disclosure.

  For example, the "sheet-like object" is not limited to paper and film, and may be any material to be transported for inspection. For example, it may be a tablet or a food enclosed in a sheet. The technology of the present disclosure can be applied to applications that examine irregularities, colors, quality, and the like of tablets or foods.

  Also, the plurality of light sources are not limited to the epi-illumination, the shaded illumination, and the transmission illumination, and any illumination method may be used. The wavelength of light used for inspection is not limited to visible light, and may be ultraviolet light or infrared light.

  The driving device 600 is not limited to a mechanism that conveys the object 300 by a roller and a motor, and may be a device such as an electric movable belt. In that case, the product itself placed on the movable belt does not have to have a sheet-like structure. When the non-sheet-like product is conveyed on the belt, it is interpreted that the combination of the belt and the product is a "sheet-like object".

  In the above embodiment, the light source is switched for each row of imaging by the image sensor, but the technology of the present disclosure is not limited to such an aspect. For example, the light source to be lit may be switched every plural rows, such as every two rows or every three rows. The resolution decreases as the number of continuously imaged rows increases while one light source is on, but the response speed required for each light source is reduced.

  The technology of the present disclosure can be used for applications such as inspection of products in factories or warehouses.

DESCRIPTION OF SYMBOLS 100 Camera 110 Optical system 120 Image sensor 121 Semiconductor substrate 122a, 122b, 122c Light detection cell 123 Micro lens 130 Signal processing circuit 200, 200A, 200B, 200C Light source 300 Object 400 Optical member 500 Control circuit 600 Driving device

Claims (7)

An inspection apparatus for inspecting a sheet-like object conveyed in a first direction by a driving device, comprising:
A plurality of light sources arranged to illuminate the same part of the object with light when the object is stationary;
A linear image sensor including a plurality of light detection cells arranged in a second direction crossing the first direction, wherein the linear image picks up a portion of the object irradiated with the light at regular intervals. Sensor,
A control circuit for controlling the plurality of light sources, in which the plurality of light sources are sequentially lighted in synchronization with timing of imaging by the linear image sensor in a state where the driving device is transporting the object. Circuit,
Inspection device provided with The linear image sensor outputs a one-dimensional image signal corresponding to the amount of light detected by the plurality of light detection cells at each predetermined time interval.
The signal processing circuit further includes: generating a plurality of two-dimensional image signals based on lights from the plurality of light sources from the plurality of one-dimensional image signals output from the linear image sensor.
The inspection apparatus according to claim 1.   The inspection apparatus according to claim 1, wherein the linear image sensor is a contact image sensor. The plurality of light sources are
A first light source for causing light to be incident on the object from the side of the linear image sensor as viewed from the object, and for causing light reflected by the object to be incident on the linear image sensor;
A second light source for causing light to be incident on the object from the opposite side to the side of the linear image sensor with respect to the object, and for causing light transmitted through the object to be incident on the linear image sensor;
The inspection apparatus according to any one of claims 1 to 3, comprising The plurality of light sources are
A first light source for causing light to be perpendicularly incident on the object from the side of the linear image sensor as viewed from the object, and for causing light reflected by the object to be incident on the linear image sensor;
A second light source for causing light to obliquely enter the object from the side of the linear image sensor as viewed from the object, and for causing light reflected by the object to be incident on the linear image sensor;
A third light source for causing light to be incident on the object from the opposite side to the side of the linear image sensor with respect to the object, and for causing light transmitted through the object to be incident on the linear image sensor;
The inspection apparatus according to any one of claims 1 to 3, comprising   The control circuit repeats an operation of sequentially switching on the lighting of the first to third light sources at predetermined time intervals while the object is being transported at a constant speed in the first direction. The inspection apparatus according to 5. The inspection apparatus according to any one of claims 1 to 6.
The drive device;
, An inspection system.

Images