Image acquisition system and image acquisition method

Abstract

An image acquisition system includes a plurality of light sources that emit light to be irradiated to an object, a light source control section that switches the light source that irradiates the light to the object among the plurality of light sources, and a line scan sensor that detects light from the object after the irradiation of the light, has a pixel section in which a plurality of pixels are arranged in at least one dimension, and is capable of switching a gain value that amplifies a signal from each pixel. The line scan sensor switches the gain value in synchronization with the switching of the light source.

Description

Technical Field

[0001] This disclosure relates to an image acquisition system and an image acquisition method. Background Technology

[0002] Devices that use line sensors to obtain image information (image signals) and acquire images of objects are known (see, for example, Patent Documents 1 and 2). In the device described in Patent Document 1, a one-dimensional line sensor is used, in which CCDs are arranged in a row. White light from a halogen lamp source is irradiated onto a color film, and the transmitted light is projected onto the CCD surface. The R, G, and B signal information projected onto the CCD surface is amplified by an amplifier and converted into digital image data by an A / D conversion circuit. In the device described in Patent Document 2, data sampling, offset adjustment, and gain adjustment are performed in the analog processing unit. Then, the analog signal is converted into a digital signal in the A / D converter.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2002-229136

[0006] Patent Document 2: Japanese Patent Application Publication No. 2007-82013 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] However, in systems that acquire images of transported objects, efficient image acquisition techniques are required. Therefore, a method is considered that alternates between reflected and transmitted illumination to synchronize the scanning time of the line sensor. However, in this case, two images are required for acquisition.

[0009] This disclosure describes an image acquisition system and method that can efficiently acquire images when using multiple light sources.

[0010] Technical solutions for solving the problem

[0011] One aspect of this disclosure provides an image acquisition system, wherein the image acquisition system acquires an image of a transported object, the image acquisition system comprising: a plurality of light sources emitting light that illuminates the object; a light source control unit that switches the light source illuminating the object from the plurality of light sources; and a line scan sensor that detects light from the object after illumination, having a pixel unit having a plurality of pixels arranged in at least one dimension, and capable of switching the gain value that amplifies the signal from each pixel, wherein the line scan sensor switches the gain value synchronously with the switching of the light sources.

[0012] According to this image acquisition system, the light source control unit switches the light source, and the line scanning sensor synchronously switches the gain value that amplifies the signal from each pixel in accordance with the switching of the light source. Through this structure, the gain value of the signal from each pixel output according to different light sources can be adjusted. For example, the brightness levels of two images can be adjusted. Therefore, images can be acquired efficiently when using multiple light sources.

[0013] Alternatively, the light source control unit can switch between multiple light sources within a specified pixel period based on the width of each pixel and the transport speed of the object. In this case, by switching the light sources and the gain value within the specified pixel period, the signal-to-noise ratio (S / N ratio) can be well maintained.

[0014] Alternatively, multiple light sources may include at least one reflected light source and at least one transmitted light source. In this case, a higher precision image can be obtained through the combination of reflected and transmitted light. In particular, the inclusion of a transmitted light source among the multiple light sources is advantageous for photographing, for example, fabric-like objects or thinner objects such as paper, substrates, and films.

[0015] Alternatively, multiple light sources can emit light of different wavelengths. In this case, it is possible to efficiently acquire images corresponding to the spectral reflectance characteristics of the transported object. This is beneficial for photographing, for example, pharmaceuticals, or food, vegetables, fruits, etc., to determine their freshness and moisture content, as well as the components of the object and foreign objects.

[0016] Another aspect of this disclosure provides an image acquisition method for acquiring an image of a transported object. The image acquisition method includes: an illumination step of illuminating the object with light using multiple light sources; and a detection step of detecting light from the illuminated object using a line scanning sensor. The line scanning sensor has a pixel portion having at least one-dimensionally arranged multiple pixels and is capable of switching gain values ​​that amplify signals from each pixel. In the illumination step, the light source illuminating the object from the multiple light sources is switched. In the detection step, the gain value is switched synchronously with the switching of the light sources.

[0017] According to this image acquisition method, the light source is switched during the illumination process. During the detection process, the line scanning sensor synchronously switches the gain value that amplifies the signal from each pixel in sync with the switching of the light source. This structure allows adjustment of the gain value of the signal from each pixel output according to different light sources. For example, the brightness levels of two images can be adjusted. Therefore, images can be acquired efficiently when using multiple light sources.

[0018] Invention Effects

[0019] According to several methods disclosed herein, images can be acquired efficiently when using multiple light sources. Attached Figure Description

[0020] Figure 1 This is a diagram illustrating the structure of an image acquisition system according to an embodiment of the present disclosure.

[0021] Figure 2 It means Figure 1 A diagram showing the structure of the line scanning sensor in the image.

[0022] Figure 3 It means Figure 2 The diagram shows an example of the structure of pixels in the image.

[0023] Figure 4 This is an explanation Figure 3 A timing diagram of actions within pixels.

[0024] Figure 5 This is a timing diagram illustrating an example of the gain value switching action in a line scan sensor.

[0025] Figure 6 This is a diagram illustrating the structure of an image acquisition system according to another embodiment of the present disclosure.

[0026] Figure 7 This is a timing diagram illustrating an example of the gain value switching action in a line scan sensor.

[0027] Figure 8 This is a diagram showing images obtained during a photographic experiment on patterned blanks. Detailed Implementation

[0028] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Furthermore, in the description of the drawings, the same reference numerals are used to denote the same elements, and repeated descriptions are omitted.

[0029] First, refer to Figure 1 An image acquisition system 100 according to one embodiment of this disclosure will be described. For example... Figure 1 As shown, the image acquisition system 100 is a system for acquiring images of an object A transported along the transport direction D. The image acquisition system 100 illuminates the object A with light (visible light) from multiple light sources and acquires images using a line scan sensor 1. The image acquisition system 100 includes: a transport device 4 that transports the object A along the transport direction D at a predetermined speed; two reflecting light sources 2A and one transmitting light source 2B that respectively emit light illuminating the object A; and a line scan sensor 1 that detects reflected light from the object A generated by light illuminating it from the reflecting light source 2A and transmitted light generated by light illuminating it from the transmitting light source 2B.

[0030] The reflected light source 2A, the transmitted light source 2B, and the line scanning sensor 1 are all located in the width direction perpendicular to the conveying direction D (and...). Figure 1The object A extends relatively long in the direction perpendicular to the paper surface. Object A is an article having a predetermined length (width) in the width direction. There are no particular limitations on object A; for example, articles with a flat shape such as sheet or plate, or articles that easily transmit light, are more suitable. Additionally, objects that are fabric-like, such as cloth, or thinner articles such as paper, substrates, or films are advantageous for photography. For example, articles with a flat shape such as sheet or plate. Examples of object A include, for example, cloth or raw material made of woven or knitted fabrics. Object A can also be non-woven fabric, etc. Figure 1 In the example shown, object A has length in both the width direction and the conveying direction D.

[0031] The conveying device 4 includes, for example, a conveying section such as a belt conveyor or a roller conveyor, and a drive section such as a motor that drives the conveying section. The conveying device 4 has a defined conveying surface and a conveying path. The conveying speed v of the conveying device 4 is controlled by the conveying control unit 7, which will be described later.

[0032] The reflected light source 2A and the transmitted light source 2B are, for example, LEDs. There are no particular limitations on the type of these light sources. Any structure can be used as long as it has multiple light sources and emits light from each source. The light emitted from the light source can be, for example, visible light, infrared light, or ultraviolet light. Furthermore, the reflected light source 2A and the transmitted light source 2B can, for example, be the same light source. The reflected light source 2A and the transmitted light source 2B can, for example, have equal output. The reflected light source 2A and the transmitted light source 2B can also have different outputs. A power supply (not shown) is connected to the reflected light source 2A and the transmitted light source 2B.

[0033] Two reflective light sources 2A are disposed, for example, above the object A (the transport path). For instance, one reflective light source 2A and the other reflective light source 2A are disposed on either side of the line scan sensor 1 in the transport direction D, angled towards each other. The reflective light sources 2A and 2A are configured to irradiate light from the front side of the object A into the region where the optical axis of the line scan sensor 1 intersects with the transport path (the region extending along the width direction). A transmissive light source 2B is disposed, for example, below the object A (the transport path). The transmissive light source 2B faces vertically upwards. The transmissive light source 2B is configured to emit light from the back side of the object A into the region where the optical axis of the line scan sensor 1 intersects with the transport path. Thus, the reflective light source 2A is disposed on the same side of the transport path as the line scan sensor 1, and the transmissive light source 2B is disposed on the opposite side of the transport path from the line scan sensor 1.

[0034] The control unit 5 is, for example, a computer equipped with a processor such as a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), and input / output interfaces. The control unit 5 includes a light source control unit 6, a transport control unit 7, and a camera control unit 8. The light source control unit 6 is connected to the reflected light source 2A and the transmitted light source 2B, controlling the on and off (lighting on and off) of each. The light source control unit 6 switches between the reflected light source 2A and the transmitted light source 2B to illuminate the object A. The transport control unit 7 is connected to the drive unit of the transport device 4, controlling the operation of the transport device 4, including the transport speed. The camera control unit 8 is connected to the line scan sensor 1, controlling various operations described later, such as the switching of the gain value in the line scan sensor 1. Specifically, the camera control unit 8 controls the sensor control unit 30 of the line scan sensor 1.

[0035] The controls in the control unit 5 described above are set so that the actions of each part of the controlled object, namely the reflective light source 2A and the transmittance light source 2B, the conveying device 4, and the line scanning sensor 1, are consistent in a predetermined sequence (details will be described later).

[0036] Next, refer to Figure 2 and Figure 3 The line scanning sensor 1 of this embodiment will be described. For example... Figure 2 As shown, the line scanning sensor 1 has a plurality of pixels 101 to 102 arranged in the line direction (corresponding to the width direction of the conveying device 4). N The pixel section 3. The line scan sensor 1 is a linear image sensor. The pixel section of the line scan sensor 1 can be a structure with multiple pixels arranged in at least one dimension, or it can include pixels arranged in one or more columns.

[0037] The line scan sensor 1 has N pixels 101 to 101 of the pixel unit 3. N The readout circuit 20 and sensor control unit 30. The line scan sensor 1 is controlled by the camera control unit 8 and the sensor control unit 30, and sequentially outputs data from the readout circuit 20 to the video line 40 and to each pixel 10. n The voltage value corresponding to the amount of incident light from the photodiode contained therein. Here, N is an integer of 2 or more, and n is any integer of 1 or more but less than N. N pixels, 101 to 10 N They share a common structure and are arranged in a one-dimensional shape with a certain spacing. Each pixel has 10 pixels. n It includes a photodiode and outputs a voltage value corresponding to the amount of incident light directed onto the photodiode.

[0038] The readout circuit 20 includes N holding circuits 211 to 21 N N switches 221~22 N and N switches 231 to 23 N Each holding circuit 21 n via switch 22 n With pixel 10 n Connect the output terminal to switch 22. n Before transitioning from the ON state to the OFF state, maintain the position from pixel 10. n Output voltage value. Each holding circuit 21 n via switch 23 n Connect to video line 40, at switch 23 n When in the ON state, the maintained voltage value is output to video line 40.

[0039] Switches 221-22 N Controlled by the control signal supplied from the sensor control unit 30, they switch on / off at the same time. Switches 231-23 N Controlled by control signals from the sensor control unit 30, the switches are sequentially switched on for only a certain period of time. The sensor control unit 30 controls not only the switches 221-22 of the readout circuit 20, but also... N and switches 231-23 N Each of them is turned on / off, and also controls pixels 101 to 10. N The action of each pixel in the image.

[0040] Figure 3 This indicates that each pixel is 10. n The diagram shows the first structural example. Each pixel is 10. n It includes a photodiode 50, a MOS transistor 51, a MOS transistor 52, and a source follower amplifier 60. The source follower amplifier 60 includes a MOS transistor 61, an action control switch 62, and a current source 63.

[0041] The photodiode 50 generates charge upon light incidence. The anode of the photodiode 50 is connected to a second reference potential input terminal, to which a second reference potential (e.g., ground potential) is input. The gate of the MOS transistor 61 is connected to the cathode of the photodiode 50 via the MOS transistor 51, and to a first reference potential input terminal, to which a first reference potential (e.g., power supply potential) is input via the MOS transistor 52. The drain of the MOS transistor 61 is connected to the first reference potential input terminal.

[0042] An action control switch 62 is disposed between the source of the MOS transistor 61 and the connection node 64. The action control switch 62 can be constructed from a MOS transistor. A current source 63 is disposed between the connection node 64 and the second reference potential input terminal. The current source 63 can be constructed not only from a MOS transistor but also from a resistor.

[0043] The on / off states of MOS transistors 51 and 52 are controlled by control signals supplied from the sensor control unit 30. When MOS transistor 52 is on, the gate potential of MOS transistor 61 is initialized. When MOS transistors 51 and 52 are on, the charge accumulation in the junction capacity of photodiode 50 is initialized. When MOS transistor 51 is on and MOS transistor 52 is off, the gate potential of MOS transistor 61 becomes the potential corresponding to the amount of incident light onto photodiode 50.

[0044] The on / off state of the action control switch 62 is also controlled by a control signal supplied from the sensor control unit 30. When the action control switch 62 is in the on state, current flows from the first reference potential input terminal through the MOS transistor 61, the action control switch 62, and the current source 63 to the second reference potential input terminal, and a voltage value corresponding to the gate potential of the MOS transistor 61 is output from the connection node 64. Conversely, when the action control switch 62 is in the off state, no current flows in the source follower amplifier 60, resulting in a power reduction state.

[0045] 10 pixels each n It also includes a capacitor element 70 and a charge amplifier 80. The charge amplifier 80 includes an amplifier 81, a capacitor section 82, and a reset switch 83.

[0046] Amplifier 81 has an inverting input terminal, a non-inverting input terminal, and an output terminal. The non-inverting input terminal of amplifier 81 is supplied with a fixed bias potential. The inverting input terminal of amplifier 81 is connected to the connection node 64 of source follower amplifier 60 via capacitor element 70.

[0047] A capacitor section 82 is disposed between the inverting input terminal and the output terminal of the amplifier 81. The capacitor section 82 stores a charge corresponding to the voltage value output from the source following the amplifier 60. The capacitance value of the capacitor section 82 can be fixed, but is preferably variable. The capacitor section 82 is configured by including a capacitor element 84, a capacitor element 85, and a switch 86, allowing the capacitance value to be variable. The capacitor element 85 and the switch 86 are connected in series and are arranged in parallel with the capacitor element 84. Depending on whether the switch 86 is on or off, the capacitance value of the capacitor section 82 varies, resulting in different gains (gain values) of the charge amplifier 80. The on / off state of the switch 86 is controlled by a control signal supplied from the sensor control unit 30.

[0048] A reset switch 83 is connected in parallel with capacitor 82 between the inverting input terminal and the output terminal of amplifier 81. When reset switch 83 is in the ON state, the charge accumulation in capacitor 82 is reset. When reset switch 83 is in the OFF state, a voltage value corresponding to the charge accumulation and capacitance value of capacitor 82 is output from the output terminal of amplifier 81. The ON / OFF state of reset switch 83 is controlled by a control signal supplied by sensor control unit 30.

[0049] Figure 4 This indicates that each pixel is 10. n The timing diagram of the action. The action control switch 62 is switched on / off at regular intervals. During the period when the action control switch 62 is on, from pixel 10... n The output voltage corresponds to the gate potential of MOS transistor 61; at switch 22 n Before the transition from the ON state to the OFF state, a holding circuit 21 is used. n Keep from pixel 10 n The output voltage value. During the period when the action control switch 62 is in the open state, N switches 231 to 23... N Each circuit is switched on only for a certain period of time, and is held on by N holding circuits 211 to 21. N The maintained voltage values ​​are sequentially output to video line 40.

[0050] During the period when the action control switch 62 is in the ON state, current flows through the source follower amplifier 60; conversely, during the period when the action control switch 62 is in the OFF state, no current flows through the source follower amplifier 60. The length of the period during which the action control switch 62 is in the ON state can be set to, for example, 15% of the ON / OFF switching cycle. In this embodiment, the line scan sensor 1 can set the action control switch 62 to the OFF state when not in use, thus suppressing power consumption. The restart of the source follower amplifier 60 when the action control switch 62 switches from the OFF state to the ON state is rapid. Therefore, when the source follower amplifier 60 is not in use, the action control switch 62 can be set to the OFF state, and the source follower amplifier 60 can be set to a power decrease state.

[0051] Furthermore, in the line scan sensor 1, by including a charge amplifier 80, when the motion control switch 62 is in the off state, the reset switch 83 is in the on state, and the charge accumulation in the capacitor 82 is reset. Additionally, while the reset switch 83 is in the on state, the switching switch 86 is turned on / off, changing the capacitance value of the capacitor 82. That is, the line scan sensor 1 can switch the output of signals from each pixel 10. nThe signal amplification gain value. During the period when the action control switch 62 is in the off state, the reset switch 83 and switch 86 are switched on / off in the charge amplifier 80.

[0052] Next, refer to Figure 5 Explain the relationship between the switching times of the reflected light source 2A and the transmitted light source 2B in the image acquisition system 100 and the switching times of the gain value in the line scanning sensor 1. Figure 5 This is a timing diagram illustrating an example of the gain value switching action in a line scan sensor.

[0053] like Figure 5 As shown, in the line scanning sensor 1, gain switching is possible when the reset switch 83 is in the ON state. During the period when this gain switching is possible, the gain is changed to the necessary value. The necessary gain value is, for example, a value corresponding to the spectral reflectance characteristics of the object being transported. By setting the gain value to an appropriate value, for example, the S / N ratio is improved, making image detection of foreign objects, etc., easier.

[0054] exist Figure 5 The data also records the corresponding periods T1 and T2 for each pixel. Each pixel's corresponding period T1 or T2 constitutes one pixel period, which is based on each pixel's 10... n The period is determined by the pixel width and the conveying speed of the conveying device 4. For example, the specified pixel period is the period for each pixel 10 in the conveying direction D. n The time is an integer multiple of the pixel width divided by the transport speed of the object S. That is, when each pixel is 10... n When the pixel width increases (increases), the specified pixel period increases. Additionally, when each pixel is 10... n When the pixel width becomes shorter (fewer pixels), the specified pixel duration becomes shorter. Additionally, when the transport speed increases, the specified pixel duration becomes shorter. Conversely, when the transport speed decreases, the specified pixel duration becomes longer. This pixel duration includes the longest possible exposure time (the illumination time provided by the reflective light source 2A or the transmissive light source 2B).

[0055] The light source control unit 6 switches between the reflected light source 2A and the transmitted light source 2B during the respective pixel correspondence periods T1 and T2 (illumination process). Additionally, when the camera control unit 8 detects reflected or transmitted light using the line scan sensor 1, it controls the sensor control unit 30 to switch the gain value synchronously with the light source switching (detection process). Figure 5 The "gain switching" shown refers to each pixel 10 nThe capacitance value of capacitor section 82 in the middle is changed. When the light source is switched during one pixel period, the spatial resolution of object A decreases, but the exposure time of each illumination does not change, so signal degradation can be prevented. Furthermore, by switching the gain value in sync with the switching of the light source, the S / N ratio is maintained. In this way, the number of times the gain value is switched during one pixel period corresponds to the number of times the light source type (two in this embodiment). For example, when there are n types of light sources, the gain value can be switched n times in sync with the switching of the light source.

[0056] According to the image acquisition system 100 and image acquisition method, the light source is switched by the light source control unit 6, and the line scanning sensor 1 switches synchronously with the switching of the light source to transmit signals from each pixel 10. n The gain value of the signal amplification is adjusted accordingly. This adjusts the output from each pixel 10 based on the different light sources (reflected light source 2A or transmitted light source 2B). n The gain value of the signal can be adjusted. For example, the brightness levels of two images can be adjusted. Therefore, when using multiple light sources, images can be acquired efficiently. Two shots are not required; images can be acquired in a single shot. By using the line scan sensor 1 of this embodiment, gain can be switched at high speed without leaving any afterimages. That is, there is no impact on the readout of the next line. Therefore, images with higher accuracy can be acquired.

[0057] Based on each pixel 10 n During the specified pixel period for the width and the conveying speed of object A, the light source control unit 6 switches between multiple light sources. Therefore, by switching the light source and the gain value during the specified pixel period, the S / N ratio is well maintained.

[0058] Next, refer to Figure 6 and Figure 7 Another embodiment of this disclosure will be described. For example... Figure 6 As shown, the image acquisition system 200 differs from the previously described image acquisition system 100 in that it incorporates an RGB light source 2C that emits light with different wavelengths, replacing the reflected light source 2A and the transmitted light source 2B. In the image acquisition system 200, the light source control unit 6 controls the RGB light source 2C to switch between the B light source, the R light source, and the G light source.

[0059] In the image acquisition system 200, such as Figure 7As shown, the light source control unit 6 also switches between each of the RGB light sources 2C during the respective pixel-corresponding periods T1 and T2. Additionally, the camera control unit 8 controls the sensor control unit 30 and switches the gain value synchronously with the light source switching. When switching the light source within one pixel period, the spatial resolution does not decrease, but the exposure time for each illumination becomes shorter, thus reducing the signal strength. However, by switching the gain value synchronously with the light source switching, the signal-to-noise ratio (S / N ratio) is maintained. Thus, the number of times the gain value is switched within one pixel period corresponds to the number of times the light source type (three types in this embodiment) is selected.

[0060] The image acquisition system 200 can achieve the same function and effect as the image acquisition system 100. Furthermore, by using multiple light sources with different emitted wavelengths, images corresponding to the spectral reflectance characteristics of the transported object can be acquired efficiently. This is beneficial for capturing images of, for example, the freshness and moisture content of pharmaceuticals, or the components of food, vegetables, and fruits, as well as foreign objects. Additionally, the RGB light source 2C can be combined with the reflected light source 2A and / or the transmitted light source 2B of the previously described embodiment.

[0061] The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments. For example, light sources other than reflected light source 2A, transmitted light source 2B, or RGB light source 2C may also be used. As long as the line scanning sensor 1 is a structure that switches the gain value synchronously with the switching of the light source, it is not limited to the above embodiments. Figure 2 , Figure 3 The structure shown is not applicable. Other known structures capable of high-speed switching of gain values ​​can also be used.

[0062] As long as the gain value switching time is synchronized with the light source switching time, the gain value can be switched once or multiple times during the exposure time of the same light source.

[0063] In the image acquisition system 100, the number of reflected light sources 2A and / or transmitted light sources 2B can be appropriately varied. In the image acquisition system 100, multiple light sources may include one or more reflected light sources 2A. Multiple light sources may also include two or more transmitted light sources 2B. One or more reflected light sources and one or more transmitted light sources can also be appropriately combined in a single image acquisition system. In the image acquisition system 200, multiple RGB light sources 2C can also be provided. Furthermore, in the image acquisition system 100 or the image acquisition system 200, as light from the object A, the line scanning sensor 1 can detect, in addition to detecting reflected light or transmitted light, light such as fluorescence and scattered light.

[0064] The line scanning sensor 1 is not limited to any structure that switches its gain value synchronously with the switching of the light source. Figure 2 , Figure 3The structure shown is not applicable. Other known structures capable of high-speed switching of gain values ​​can also be used.

[0065] The specified pixel period can also be 10 pixels in the transport direction D. n The gain value is multiple (two or three times or more) the time obtained by dividing the pixel width by the transport speed of the object S. In this case, multiple light source switching is also performed within the specified pixel period, and the gain value is switched synchronously with the switching of the light source. Alternatively, the light source can be switched independently of the pixel period (regardless of the aforementioned quotient). In this case, by switching the gain value at least synchronously with the switching of the light source, image acquisition can also be achieved efficiently.

[0066] In an image acquisition system that has multiple light sources that emit light of different wavelengths (as an example, the image acquisition system 200 mentioned above), the following form may also be adopted: the light source emitting light of a certain wavelength is a reflected light source, and the light source emitting light of another wavelength is a transmitted light source.

[0067] Use with Figures 1-3 The image acquisition system 100 with the structure shown was used in a photographic experiment of a patterned blank. For example... Figure 8 As shown, by combining reflected and transmitted light, abnormalities such as holes or scratches (see the circular and triangular marks in the diagram) are detected in the acquired image. In contrast, in the imaging experiment using only reflected light, scratches were identified, but holes could not be identified. Furthermore, in the imaging experiment using only transmitted light, although scratches and holes were identified, the presence of many thin sections of the blank resulted in these thin sections appearing identical to holes or scratches.

[0068] [Explanation of reference numerals in the attached figures]

[0069] 1…line scanning sensor,

[0070] 2A…Reflected light source,

[0071] 2B…transmitted light source,

[0072] 2C…RGB light source,

[0073] 3…pixel section

[0074] 4… Conveying device,

[0075] 5…Control Department

[0076] 6…Light source control unit,

[0077] 7…Conveying Control Department

[0078] 8…Camera Control Department

[0079] 101~10 N …pixels,

[0080] 20…Readout circuit,

[0081] 40…video lines,

[0082] 50…photodiode,

[0083] 60…Source Follower Amplifier

[0084] 80…charge amplifier,

[0085] 81…amplifier

[0086] 82… Capacitor Section

[0087] 100, 200… Image acquisition system

[0088] A…object.

Claims

1. An image acquisition system that acquires an image of a transported object, wherein, This image acquisition system has the following features: Multiple light sources emit light that illuminates the object. A light source control unit that switches between the plurality of light sources that illuminate the object. as well as A line scanning sensor that detects light from an object after it has been illuminated by the light, has a pixel section with a plurality of pixels arranged in at least one dimension, and is capable of switching the gain value that amplifies the signal from each pixel. The gain value is switched synchronously with the switching of the light source by the line scanning sensor.

2. The image acquisition system according to claim 1, wherein, The light source control unit switches between the multiple light sources during a predetermined pixel interval based on the width of each pixel and the transport speed of the object.

3. The image acquisition system according to claim 1 or 2, wherein, The plurality of light sources includes at least one reflected light source and at least one transmitted light source.

4. The image acquisition system according to claim 1 or 2, wherein, The multiple light sources emit light of different wavelengths.

5. An image acquisition method, wherein the image acquisition method acquires an image of a transported object, wherein, The image acquisition method includes: An irradiation process that uses multiple light sources to illuminate the object; and A detection process that uses a line scanning sensor to detect light from the object after it has been illuminated by the light. The line scanning sensor has a pixel section with at least one-dimensionally arranged pixels, and is capable of switching the gain value for amplifying signals from each pixel. In the irradiation process, the light source that illuminates the object from among the plurality of light sources is switched. In the detection process, the gain value is switched synchronously with the switching of the light source.

Images