Image processing device, image processing method and program

Abstract

To provide an image processing device capable of correctly detecting a mark formed on a sheet with visible light permeability.SOLUTION: An image processing device includes: acquisition means for reading a transparent substrate (111) transported with transportation means which a printing device (116) printing images page by page has, the transparent substrate (111) having a mark showing a head position of the page printed thereon, so as to acquire a brightness value; calculation means for calculating a distance that the transparent substrate (111) is transported by the transportation means while the brightness value acquired by the acquisition means is within a certain range; and determination means for determining a position of the mark on the transparent substrate (111) on the basis of the distance calculated by the calculation means.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a technique for detecting a mark that indicates a printing position. [Background technology]

[0002] Conventionally, marks formed on an object have been read and detected by a scanner to perform various controls. For example, Patent Document 1 discloses a technology for detecting the position of a mark by reading a handwritten manuscript on which a mark indicating a handwritten area has been formed with a scanner and identifying pixels of the color of the mark based on luminance information and color difference information of the area including the mark. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-41673 Summary of the Invention [Problem to be solved by the invention]

[0004] There is a technology that forms a position detection mark on a sheet to be printed, and determines the leading position of the page to be printed based on the position detection mark on the sheet as it is conveyed, thereby determining the position where the image is to be formed. However, if the sheet to be printed is transparent to visible light, it is not possible to stably obtain luminance information for areas other than the marks formed on the sheet, and it is not possible to accurately detect the marks.

[0005] The present disclosure has been made in consideration of the above-mentioned problems, and aims to enable correct detection of marks formed on a sheet that is transparent to visible light. [Means for solving the problem]

[0006] An image processing device according to one aspect of the present disclosure is characterized in that it comprises: an acquisition means for acquiring a luminance value obtained by reading a transparent substrate transported by a transport means provided in a printing device that prints an image page by page, the transparent substrate having a mark indicating the start position of the page printed thereon; a calculation means for calculating a distance over which the transparent substrate is transported by the transport means while the luminance value acquired by the acquisition means is within a certain range; and a determination means for determining the position of the mark on the transparent substrate based on the distance calculated by the calculation means. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to correctly detect a mark formed on a sheet that is transparent to visible light. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram illustrating an example of a device configuration of an image processing device. [Figure 2] FIG. 2 is a diagram illustrating an example of a control configuration of the image processing apparatus. [Figure 3] 10 is a flowchart illustrating a page position determination process. [Figure 4] FIG. 10 is a diagram showing an example of a position where a mark is formed on a page. [Figure 5] 10 is a flowchart illustrating a mark detection process. [Figure 6] 10A and 10B are schematic diagrams illustrating an example of the relationship between the conveyance distance of a sheet and the luminance value of a mark. DETAILED DESCRIPTION OF THE INVENTION

[0009] Preferred embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the present disclosure, and the combinations of features described in the following embodiments are not necessarily essential to the solutions of the present disclosure. Note that the same components are given the same reference numerals. In this embodiment, an image forming apparatus is used as an example of an information processing apparatus, but the present disclosure is not limited to this.

[0010] <<Embodiment>> [overview] Conventionally, among substrates such as roll paper, there are substrates (hereinafter also referred to as sheets) on which label stickers are formed. A backing sheet is removably attached to such sheets via an adhesive layer, and the label-formed portion is peeled off from the backing sheet to be used as a label sticker. When producing a large number of label stickers, the sheet may be divided into multiple pages for use. When a sheet is divided into multiple pages, a mark may be formed on a page among the multiple pages on which a print job is to be started, and image formation based on the print job may be initiated by detecting the mark. Recently, some sheets and backing sheets are both visible light transmissive. Such sheets and backing sheets can also be used to form entertaining labels, such as those featuring characters from animation. However, because brightness values ​​are used to detect the marks, if the sheet is a transparent substrate that is visible light transmissive and the backing sheet is a transparent backing sheet that is also visible light transmissive, there is a risk of erroneous detection of the brightness values. For example, a substrate, various units, etc. are provided along the sheet transport path. When detecting marks using the luminance value of a visible light-transmitting sheet while it is being transported along such a transport path, situations are anticipated in which the luminance value of the mark is unstable due to the installation environment, such as the substrate, various units, etc. Therefore, in the present disclosure, the position of a mark on a transparent substrate is determined based on the distance the transparent substrate is transported while the luminance value of a mark printed on the transparent substrate and indicating the top position of a page is within a certain range. According to this operation, the position of the mark is determined as long as the luminance value of the mark is stable while the transparent substrate is being transported, thereby enabling accurate detection of marks formed on a visible light-transmitting sheet. Furthermore, because the position of the mark is accurately detected, it is possible to appropriately control the print start position and print position of an image based on a print job (hereinafter also referred to as a job, as appropriate). Furthermore, it is also possible to identify and control the image analysis position for each page of the sheet based on the relationship between the mark and the image formation area where the image is formed. The present disclosure will be described in detail below.

[0011] [Device configuration] FIG. 1 illustrates an example of the configuration of an image forming system 100. The image forming system 100 is an apparatus that forms images on sheets. Specifically, the sheets are continuous paper (hereinafter also referred to as roll paper) 111 on which continuous images can be formed. The roll paper 111 may have a backing sheet removably attached. The backing sheet is removably laminated on one side of the sheet. A mark is also formed on the other side of the sheet. Details of this mark will be described later. The mark is printed at the beginning of a page to be formed on the sheet and serves as an identifier for identifying the beginning of the page. Therefore, by detecting the mark, the beginning of the page is determined, and when an image is formed in a predetermined image formation area on the page, the position at which the image is to be formed can be accurately identified. In the example illustrated in FIG. 1, the image forming system 100 includes a paper feeder 104, a first printing device 116, a second printing device 115, a paper output device 105, a control PC 119, and a UI (User Interface) operation panel 101. Note that a device including some of the functions that realize the image forming system 100 is also called an image processing device.

[0012] The device configuration of the image forming system 100 will be described in detail below. The paper feeder 104 is a device that stores roll paper 111 and supplies the stored roll paper 111 to the subsequent stage. The paper feeder 104 is equipped with a transport roller, a paper feed roller, a skew correction device 110, etc. The paper feeder 104 rotates the paper tube of the roll paper 111 around a rotation axis 117, and supplies the roll paper 111 wound around the paper tube via the transport roller and paper feed roller to the subsequent stage at a constant transport speed. In the example shown in FIG. 1, a first printing device 116 (also referred to as a printing device) is located downstream of the paper feeder 104. The skew correction device 110 appropriately corrects positional deviation of the roll paper 111 as it is transported. The first printing device 116 is a unit that prints spot colors. Specifically, the first printing device 116 includes a first print head 103, a drying device 112, a cooling device 113, and a cooling device 114. The first print head 103 is a device that prints images in spot colors (e.g., white ink) other than the basic printing colors (CMYK). The image formation method of the first print head 103 is, for example, an inkjet method, but it can also be an electrophotographic method, and is not particularly limited. The first print head 103 prints marks on the roll paper 111, for example, in white ink. The drying device 112 dries the roll paper 111 on which the image has been printed in spot colors. The cooling devices 113 and 114 cool the roll paper 111 that has become hot due to drying by the drying device 112. The cooled roll paper 111 is supplied to the rear side of the first printing device 116. A second printing device 115 (also referred to as a rear-stage printing device) is arranged rearward of the first printing device 116. The second printing device 115 is a unit that prints in the basic printing colors.

[0013] The second printing device 115 includes a mark detection sensor 120, a second print head 102, a drying device 106, a scanner device 107, a cooling device 108, and a cooling device 109. The mark detection sensor 120 detects marks printed on the roll paper 111 by detecting the brightness value of the mark. The mark detection sensor 120 is composed of, for example, a light-emitting unit and a light-receiving unit. The light-emitting unit emits light onto the roll paper 111. The light-receiving unit receives light reflected from the roll paper 111 and detects the brightness value based on the received light. The second print head 102 is a device that prints a predetermined image using the basic printing colors. The image formation method of the second print head 102 is, for example, an inkjet method, but is not particularly limited and may also be an electrophotographic method. The second print head 102 determines the start position of a page to be composed on the roll paper 111 based on the marks detected by the mark detection sensor 120. The second print head 102 prints an image on the roll paper 111 based on the determined start position. The drying device 106 dries the roll paper 111 on which an image has been printed in the basic printing colors. The cooling devices 108 and 109 cool the roll paper that has become hot due to the drying by the drying device 106. The scanner device 107 supplies the roll paper cooled by the cooling devices 108 and 109 to the rear stage. The paper discharge device 105 is located rear of the second printing device 115. The paper discharge device 105 is a device that takes up the roll paper 111 transported from the second printing device 115. The paper discharge device 105 is equipped with a transport roller, a paper feed roller, etc. In the paper discharge device 105, the roll paper 111 is wound around a paper core of a rotating shaft 118 and held in a roll shape. The roll paper 111 passes through a transport roller and a paper feed roller and is wound onto a paper core of a rotating shaft 118 at a constant transport speed.

[0014] The roll paper 111 can be installed as follows. That is, before printing starts, the roll paper 111 is passed through the paper feeder 104. After the roll paper 111 is installed in the paper feeder 104, the leading edge of the roll paper 111 passes over the skew correction device 110. Next, in the first printing device 116, the roll paper 111 passes under the first print head 103, under the drying device 112, over the cooling device 113, and over the cooling device 114. Next, in the second printing device 115, the roll paper 111 passes under the mark detection sensor 120, under the second print head 102, under the drying device 106, over the cooling device 108, and over the cooling device 109, and then passes through the scanner device 107. After passing through the scanner device 107, the roll paper 111 is wound around the paper discharge device 105. A control PC 119 is installed in the paper discharge device 105. A UI operation panel 101 is installed on the control PC 119. A user submits a print job to the control PC 119. After submitting the print job, the user starts printing by operating a print start button (not shown) displayed on the UI operation panel 101 via the UI operation panel 101. The printed image is read by the scanner device 107. The read image is analyzed by the control PC 119 and inspected for defects in the printed matter.

[0015] [Control configuration] Next, the control configuration of the image forming system 100 will be described in detail. FIG. 2 is a diagram illustrating an example of the control configuration of the image forming system 100. As shown in FIG. 2, the image forming system 100 includes a paper conveying unit 201, an image forming unit 202, a communication unit 203, a control unit 204, a storage unit 205, an operation / display unit 206, an inspection unit 207, and a paper feed control unit 208. The control unit 204 is a mechanism that controls the paper conveying unit 201, the image forming unit 202, the communication unit 203, the control unit 204, the operation / display unit 206, the inspection unit 207, and the paper feed control unit 208. The control unit 204 is configured, for example, with a central processing unit (CPU), a random access memory (RAM), and the like. The CPU of the control unit 204 reads various programs, such as a system program and a processing program, stored in the storage unit 205, loads them into the RAM, and executes various processes in accordance with the loaded programs. For example, the control unit 204 can perform image formation processing to execute a print job in response to a user's instruction. User instructions are received, for example, from the control PC 119. The storage unit 205 is configured, for example, with non-volatile semiconductor memory (so-called flash memory), an HDD (Hard Disk Drive), or a combination of these. The storage unit 205 stores various programs, such as system programs and processing programs, executed by the control unit 204, as well as various data required to execute these programs. The paper transport unit 201 has multiple rollers. The paper transport unit 201 is a transport mechanism for the roll paper 111 inside the image forming system 100. For example, a situation is envisioned in which the roll paper 111 is transported from the paper feed control unit 208 to the image forming unit 202. In this situation, the paper transport unit 201 transports the roll paper 111 transported from the paper feed control unit 208 to the image forming unit 202. Another situation is envisioned in which the roll paper 111 is transported from the image forming unit 202 to the take-up control unit 209. In this situation, the paper transport unit 201 transports the roll paper that has passed through the image forming unit 202 to the take-up control unit 209. Next, the mechanisms of the paper feed control unit 208, the image forming unit 202, and the take-up control unit 209 will be described.The paper feed control unit 208 is a mechanism inside the paper feed device 104 that transports the roll paper 111 and supplies it to the image forming unit 202. For example, in response to a control command from the control unit 204, the paper feed control unit 208 supplies the roll paper 111 to the image forming unit 202. The image forming unit 202 is a mechanism that forms an image on the roll paper 111 supplied from the paper feed control unit 208, based on print data for which an output command has been received, in each of the second printing device 115 and the first printing device 116. After forming an image on the roll paper 111, the image forming system 100 transports the roll paper 111 with the image formed on it toward the rewinding control unit 209. The rewinding control unit 209 is a mechanism that rewinds the roll paper 111 inside the paper discharge device 105.

[0016] The communication unit 203 is a mechanism for transmitting and receiving various data to and from external devices (e.g., personal computers) connected to a communication network such as a LAN (Local Area Network) or a WAN (Wide Area Network). The communication unit 203 is, for example, constituted by a communication control card such as a LAN card. The operation display unit 206 is a mechanism for receiving user input and displaying the received user input information. The operation display unit 206 includes a display unit 206a and an operation unit 206b. The display unit 206a is a mechanism for displaying various information on a display screen in accordance with a display control signal input from the control unit 204. The display unit 206a may be, for example, constituted by a liquid crystal display (LCD). The operation unit 206b is a mechanism for receiving various input operations by the user and outputting operation signals to the control unit 204. The operation unit 206b is constituted by various operation keys such as a numeric keypad and a start key. The operation unit 206b may be, for example, constituted by a touch panel. The operation display unit 206 may be configured as a liquid crystal display with a touch panel, which is formed by laminating a touch panel on a liquid crystal display. The operation display unit 206 may be used, for example, to set various information related to a job when executing the job. Examples of the various information related to the job include the paper to be used, printing speed, number of prints, number of copies, print length, print weight, and print diameter. The user can arbitrarily set at least one of the conditions of the various information related to the job via the operation display unit 206.

[0017] The inspection unit 207 is a mechanism that checks whether an image has been printed on the roll paper 111 without any ejection defects. When a detection pattern for ejection defect inspection is printed by the image forming unit 202, the inspection unit 207 determines whether there are any ejection defects in the image printed on the roll paper 111 by reading it with the scanner device 107. If the inspection unit 207 determines that there is an ejection defect, it stops the image forming system 100. Note that in the above example, an inspection is described in which the image of the detection pattern printed by the image forming unit 202 is read by the scanner device 107, but this is not limiting. For example, the inspection may be performed by directly reading the image printed on the roll paper 111 with a camera (not shown) or the scanner device 107. Alternatively, the inspection may be performed by monitoring the ink ejection status from the nozzles.

[0018] (Overview of printing operation) Next, the printing operation on the roll paper 111 in the image forming system 100 will be described. First, the user creates print job data in an external device and sets the print job's print settings and the delivery roll number of the roll paper 111. Next, the user sends the print job's print setting information and the delivery roll number setting information for the roll paper 111 to the image forming system 100 via the communications network. The control unit 204 receives the job data sent from the external device via the communications unit 203, as well as a job ticket (also called print settings) that includes the print job's print setting information and the delivery roll number setting information for the roll paper 111. The image forming system 100 then performs printing according to the job ticket. Incidentally, the image forming system 100 can print without image misalignment by accurately detecting the position of the page to be formed on the roll paper 111. One operation for detecting the page's position is to detect a mark. Next, the mark detection operation will be described.

[0019] (Page position determination process) FIG. 3 is a flowchart illustrating the page position determination process. The process illustrated in FIG. 3 is realized by the control unit 204 executing a program stored in the storage unit 205. The process illustrated in FIG. 3 may be executed, for example, when the page position determination process is called. That is, the process illustrated in FIG. 3 is realized by the CPU of the control unit 204. Note that some or all of the functions of the steps in FIG. 3 may be realized by hardware such as an ASIC or electronic circuit. The symbol "S" in the description of each process indicates the step in the flowchart. The process illustrated in FIG. 3 mainly includes the following processes: a process for setting the sheet type (S301), a mark detection setting process according to the sheet type (S302 to S304), a mark printing process (S305), a mark detection process (S306), and a page position determination process based on the mark (S307). The process illustrated in FIG. 3 differs depending on whether the sheet and mount are transparent. Hereinafter, a transparent sheet, i.e., a sheet that is transparent to visible light, will be referred to as transparent paper (also referred to as a transparent substrate), and a sheet will be referred to as paper. Also, a transparent mount, i.e., a mount that is transparent to visible light, will be referred to as a transparent mount. Visible light transparency means that the mount has the ability to transmit visible light. Therefore, 100% visible light transmittance is not required. The process shown in FIG. 3 detects the brightness values ​​of multiple detection marks on transparent paper and the transparent mount, and determines that marks are present if the detected brightness values ​​are within a certain range. The determined marks are then used to identify the top position of the page, enabling control of the image formation position. In this embodiment, the top position of the page is identified by detecting the detection marks with the mark detection sensor 120, and an image is formed by the second print head 102 in alignment with the image formed by the first print head 103. Since this embodiment uses roll paper for printing, the following process will be described assuming a use case in which paper is pre-loaded at the mark detection sensor 120. However, this use case is not limited to roll paper. In the case of cut paper, it is also possible to transport only one sheet, determine the detection mark by manual insertion, and set it using various methods such as user settings.Therefore, the means for selecting the detection marks to be used is not limited to roll paper in this embodiment. The process shown in Fig. 3 may also be performed externally to the first printing device 116 and the second printing device 115. For example, the process shown in Fig. 3 may be performed by the control PC 119. The process of S301 to S307 will be described in detail below.

[0020] In S301, the CPU of the control unit 204 (hereinafter referred to as the CPU) determines the type of paper on which the mark is to be printed. In this embodiment, an example of a configuration in which the user sets the paper type via the operation unit 206b is adopted. Note that, as will be described in detail later, mark detection is not limited to determining the mark's brightness value. For example, the ultrasonic sensor may be installed upstream on the conveyance path of the second printing device 115. In such a situation, the paper type may be automatically set. In S302, the CPU determines whether the set paper type is transparent paper and a transparent backing. If the set paper type is transparent paper and a transparent backing, the CPU advances the process of S302 to S303; otherwise, the CPU advances the process to S304. In S303, the CPU sets mark detection for transparent paper. In S304, the CPU sets mark detection for non-transparent paper. In S305, the CPU prints a detection mark at the mark printing position, which will be described later. In S306, the CPU uses the mark detection sensor 120 to cause the image forming unit 202 to acquire a luminance value and detect the mark. Details of the processing related to the luminance value will be described later with reference to Fig. 5. Finally, in S307, the CPU uses the detected mark to determine the start position of the page and decides the start position of the page.

[0021] (Mark formation position) FIG. 4 is a diagram showing an example of the position of marks on a page. FIG. 4 shows an example of detection marks formed on the roll paper 111 to identify the top of a page when printing. Separate marks may also be formed to identify the image formation area. Mark formation is not limited to the use case of identifying the top of a page in this embodiment. FIG. 4 also shows an example of the printing position of detection marks when printed with the printing position fixed. The area allocation configuration 400 is the configuration for one page when printing on the roll paper 111. An image formation area (also referred to as an image area) is allocated between the left and right margins of the area allocation configuration 400 along the transport direction. An image based on a print job is formed in this image area. A white detection mark 401 is printed in one of the left and right margins of the area allocation configuration 400 along the transport direction. The color of the detection mark is not limited to that of this embodiment. The color of the detection mark may be changed depending on the characteristics of the paper, and the number of detection marks may also be changed. Since the position of the mark from the beginning of the image area is fixed, it is possible to identify the beginning of the page using the transport distance of the detection mark used.

[0022] (Mark detection operation) FIG. 5 is a flowchart illustrating the mark detection process. The process shown in FIG. 5 is implemented by the control unit 204 executing a program stored in the memory unit 205. The process shown in FIG. 5 is executed when the mark detection process in S306 of FIG. 3 is called. That is, the process shown in FIG. 5 is implemented by the CPU of the control unit 204. Note that some or all of the functions of the steps in FIG. 5 may be implemented by hardware such as an ASIC or electronic circuit. The symbol "S" in the description of each process indicates the step in the flowchart. The process shown in FIG. 5 is executed for all detection marks formed on the roll paper 111 (S501 to S508). During execution, it is first determined whether the brightness value L detected by the mark detection sensor 120 is within the range between the lower threshold value LT1 and the upper threshold value LT2 (S503). Next, if the brightness value L detected by the mark detection sensor 120 is within the range between the lower threshold LT1 and the upper threshold LT2, detection of the transport distance of the roll paper 111 and the brightness value L continues (S504, S505). During this process, if the brightness value L is stable and the transport distance reaches the distance threshold AT, it is detected as a mark (S506). If not, a determination is made again as to whether the brightness value L is within the range between the thresholds LT1 and LT2 (S501 to S508). Here, the thresholds LT1 and LT2 may be obtained by various trials for various roll papers 111. The distance threshold AT is a value set based on the size of the mark, and may be set to the value of the minimum size of the mark, for example. If the distance threshold AT is set to the value of the minimum size of the mark, the minimum size of the mark can be detected by the distance threshold AT. That is, in the case of transparent paper, the process shown in Fig. 5 is a process in which the control unit 204 uses the mark detection sensor 120 to detect the mark by obtaining the brightness value obtained by reading the mark detection sensor 120. Note that the process shown in Fig. 5 may be performed outside the first printing device 116 and the second printing device 115. For example, the process shown in Fig. 5 may be performed by the control PC 119. The process of S501 to S508 will be described in detail below.

[0023] In S501, the CPU of the control unit 204 (hereinafter referred to as the CPU) determines whether all detection marks have been determined. If all detection marks have been determined, the CPU ends the processes of S501 to S508 and proceeds to the process of S307 in FIG. 3. If all detection marks have not been determined, the CPU repeats the processes of S501 to S508. In S502, the CPU acquires a luminance value L from the mark detection sensor 120. In S503, the CPU determines whether the luminance value L is equal to or greater than a lower threshold value LT1 of the luminance value and equal to or less than an upper threshold value LT2 of the luminance value. In this embodiment, the range of values ​​that the mark detection sensor 120 can take is set to 0 to 255, with the lower threshold value LT1 = 50 and the upper threshold value LT2 = 100. The thresholds may be set depending on the accuracy of the mark detection sensor 120 and are not limited to this. If LT1≦L≦LT2, the CPU advances processing from S503 to S504. On the other hand, if LT1≦L≦LT2 is not true, the CPU advances processing from S503 to S507. In S504, the CPU calculates the detection distance AD ​​where LT1≦L≦LT2 holds. Here, the detection distance AD ​​is the transport distance of the roll paper 111 while the brightness value L is in the range of LT1≦L≦LT2. The detection distance AD ​​may be calculated based on the detection results of the mark detection sensor 120. Alternatively, the detection distance AD ​​may be calculated based on, for example, the rotation speed of the drive roller among the multiple rollers in the paper transport unit 201. Alternatively, the detection distance AD ​​may be calculated based on the detection results of multiple passage detection sensors (not shown) provided along the roll paper transport path. In S505, the CPU determines whether the detection distance AD ​​is equal to or greater than the distance threshold AT. In other words, it determines whether the roll paper 111 has been transported by the size of the mark. Specifically, it is determined whether the fluctuation range of the luminance value L continues to be within the tolerance range until the detection distance AD ​​reaches the distance threshold AT. In other words, if it is the same mark, the luminance value of that mark will be stable at a constant value. Therefore, if the luminance value L is constant while the detection distance AD ​​is being detected, it means that the same mark has been continuously detected. Here, the tolerance range may be set to a range in which the fluctuation range of the luminance value L falls within the error range.For example, even if dust or dirt adheres to a part of the mark, the luminance value obtained by reading with the mark detection sensor 120 fluctuates. In this case, if the fluctuation range is within the allowable range, the luminance value L may be regarded as a constant value. Also, in the present embodiment, the distance threshold AT is set to 2 mm. When AD ≧ AT, in S506, the CPU detects it as a mark. That is, the position of the mark is determined. When AD < AT, in S507, the CPU initializes the detection distance AD to 0 and proceeds to the process of detecting the next mark. In the present embodiment, although the distance threshold AT is set to 2 mm, it may be changed according to the size of the mark actually printed.

[0024] (Relationship between the conveyance distance of the sheet and the luminance value of the mark) FIG. 6 is a schematic diagram illustrating an example of the relationship between the sheet conveyance distance and the mark brightness value. The sticker label 601 is composed of transparent paper and a transparent backing. The device component 602 is located below the paper (vertically below) and is shown schematically as being visible through the paper. The device component 602 may be, for example, an internal unit of the image forming system 100 or a printed sheet of paper being conveyed. Because the sticker label 601 is transparent, light emitted from the light-emitting unit of the mark detection sensor 120 reaches the device component 602 located below the sticker label 601. Therefore, the brightness value obtained from the light incident on the light-receiving unit of the mark detection sensor 120 is not constant. In other words, the graph at the top of FIG. 6 shows that a brightness value can be obtained from the mark detection sensor 120, but the value is not stable. If the brightness value L detected by the mark detection sensor 120 is between the threshold value LT1 604 and the threshold value LT2 605, calculation of the detection distance AD ​​606 begins. Here, as shown in FIG. 6 , the distance threshold AT607 between auxiliary lines 608 and 609 is set to the size of the mark along the sheet conveyance direction. Therefore, as shown in FIG. 6 , the position of the mark can be determined as long as the fluctuation range of the brightness value L remains within the allowable range until the detection distance AD606 reaches the distance threshold AT607. In other words, the position of the mark on the transparent substrate is determined based on the distance the transparent substrate is conveyed while the brightness value of the mark, which is printed on the transparent substrate and indicates the top position of the page, is within a certain range. Note that, as the color of the mark becomes darker, the brightness value L decreases. Conversely, as the color of the mark becomes lighter, the brightness value L increases. Therefore, the thresholds LT1 and LT2 may be set appropriately depending on the color of the mark.

[0025] As described above, the image processing device includes an acquisition unit, a calculation unit, and a determination unit. The acquisition unit acquires a luminance value by reading a transparent substrate transported by a transport unit included in a printing device that prints an image page by page, the transparent substrate having a mark indicating the top position of the page printed thereon. The calculation unit calculates a distance the transparent substrate is transported by the transport unit while the luminance value acquired by the acquisition unit is within a certain range. The determination unit determines the position of the mark on the transparent substrate based on the distance calculated by the calculation unit. According to this operation, if the luminance value of the mark is stable while the transparent substrate is transported, the position of the mark is determined, making it possible to accurately detect a mark formed on a sheet that is transparent to visible light.

[0026] The determining means may determine that the luminance value acquired by the acquiring means remains within the certain range if it continues to be within the allowable range. According to this operation, even if the luminance value fluctuates slightly due to the presence of dust or dirt on part of the mark when detecting the luminance value, it can be treated as being within the error range.

[0027] The transparent substrate may further include an image forming unit that has a transparent backing paper removably attached thereto and that has white ink and that forms a mark on the transparent substrate with the white ink. With this configuration, the mark is formed in white, which has the highest brightness value, making it easier to detect differences in brightness between the mark and the transparent substrate and the transparent backing paper.

[0028] A transparent backing is removably attached to the transparent substrate. The device may further include an image forming unit that has ink of at least one color selected from cyan, magenta, and yellow and forms a mark on the transparent substrate using the ink of at least one color selected from cyan, magenta, and yellow. This configuration increases the color variation of the mark, allowing the mark to be formed in a color suited to the detection environment of the mark.

[0029] The conveying means may also convey roll paper as the transparent substrate. This operation makes it possible to detect the mark of the present disclosure on long paper such as roll paper.

[0030] Furthermore, when the brightness value acquired by the acquisition means is within a range between a preset first threshold (also referred to as an upper threshold LT2) and a second threshold (also referred to as a lower threshold LT1) that is lower than the first threshold, the calculation means performs the following operation. That is, the calculation means may start calculating the distance the transparent substrate is transported. With this configuration, it is possible to narrow down the brightness values ​​and detect the mark.

[0031] The image forming means may also form a mark at the top position of the page, and such an operation makes it possible to detect the top position of the page by detecting the mark.

[0032] Furthermore, a detection means (e.g., a mark detection sensor 120) may be further provided, which is installed in accordance with the position where the mark is formed on the transparent substrate and reads the transparent substrate to obtain a brightness value. With this configuration, it is possible to appropriately adjust the distance between the mark and the detection means.

[0033] Furthermore, if the luminance value remains within the allowable range, the calculation means may increase the distance as the transport of the transparent substrate progresses. This operation allows correlation between the distance and a state in which the luminance value of the mark is stable, thereby enabling accurate mark detection.

[0034] The determining means may also determine the position of the mark when the calculated distance reaches a distance threshold AT set based on the size of the mark. This operation allows the size of the mark to be correlated with the distance threshold AT, making it possible to accurately detect the mark.

[0035] The printer may further include a subsequent-stage image forming unit disposed downstream of the image forming unit and having an ink different from the white ink. The subsequent-stage image forming unit may have at least one color ink selected from cyan, magenta, and yellow as the different ink. The subsequent-stage image forming unit may form an image based on a print job in at least one color selected from cyan, magenta, and yellow in an area different from the area where the mark is present. This operation allows for an increased variety of mark colors.

[0036] Furthermore, the subsequent image forming unit may specify an area different from the mark as the image forming area where the image based on the print job is to be formed, based on the position of the mark determined by the determining unit. By performing such an operation, the image forming area can be specified in an accurate position.

[0037] Furthermore, when a different area is specified as the image formation area, the subsequent image formation unit may start forming an image in the image formation area based on the print job. By performing such an operation, the image can be formed in an accurate position.

[0038] <<Variation 1>> Although an example has been described in which the first print head 103 of the first printing device 116 prints an image using a special color such as white ink, the present invention is not limited to this. The first print head 103 may print an image using a basic printing color. For example, the first print head 103 may have ink of at least one color from among cyan, magenta, and yellow, instead of white ink. In this case, if the sheet and backing paper are both visible light transmissive, the first print head 103 may form a mark using ink of at least one color from among cyan, magenta, and yellow. This operation makes it possible to print a mark in color.

[0039] <<Variation 2>> Although an example has been described in which it is determined whether the luminance value L is equal to or greater than LT1 and equal to or less than LT2, and then the detection distance AD ​​is calculated and a determination is made as to whether the luminance value L is a constant value, the order is not particularly limited to this. For example, it may be determined whether the luminance value L is a constant value, and then the detection distance AD ​​is calculated and a determination is made as to whether the luminance value L is equal to or greater than LT1 and equal to or less than LT2.

[0040] (Other embodiments) Although various examples and embodiments of the present disclosure have been shown and described above, the spirit and scope of the present disclosure are not limited to the specific descriptions in this specification. The present disclosure is not limited to the above-described embodiments, and various modifications may be made. Furthermore, the present disclosure may be realized by appropriately combining parts of the above-described embodiments.

[0041] Furthermore, in this embodiment, an example has been described in which the distance threshold value AT is used to detect the mark, but the present invention is not limited to this. For example, if the transport speed of the roll paper 111 is constant, the process may determine whether the roll paper 111 has been transported long enough to detect the entire mark.

[0042] The present invention can also be realized by supplying a program that realizes one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program. It can also be realized by a circuit (e.g., ASIC) that realizes one or more functions. The program may also be provided by recording it on a computer-readable storage medium.

[0043] The disclosure of the present embodiment includes configurations typified by the following image processing device, image processing method, and program.

[0044] <Configuration 1> an acquisition unit for acquiring a luminance value obtained by reading a transparent substrate conveyed by a conveyance unit included in a printing device that prints an image for each page, the transparent substrate having a mark indicating the top position of the page already printed thereon; a calculation means for calculating a distance over which the transparent substrate is transported by the transport means while the luminance value acquired by the acquisition means is within a certain range; a determining means for determining a position of the mark on the transparent substrate based on the distance calculated by the calculating means; An image processing device comprising:

[0045] <Configuration 2> The image processing device according to configuration 1, characterized in that the determination means determines that the luminance value acquired by the acquisition means is within the certain range when the luminance value continues to be within an allowable range of a fluctuation range of the luminance value.

[0046] <Configuration 3> a transparent backing paper is releasably attached to the transparent substrate; 3. The image processing device according to configuration 2, further comprising image forming means having white ink and forming the mark on the transparent substrate with the white ink.

[0047] <Configuration 4> a transparent backing paper is releasably attached to the transparent substrate; The image processing device according to configuration 2, further comprising an image forming means having ink of at least one color selected from cyan, magenta, and yellow, and forming the mark on the transparent substrate with ink of at least one color selected from cyan, magenta, and yellow.

[0048] <Configuration 5> 4. The image processing apparatus according to claim 2, wherein the transport means transports roll paper as the transparent substrate.

[0049] <Configuration 6> 5. The image processing device according to any one of configurations 2 to 4, wherein the calculation means starts calculating the distance when the luminance value acquired by the acquisition means is within a range between a preset first threshold and a second threshold that is lower than the first threshold.

[0050] <Configuration 7> 5. The image processing device according to claim 3, wherein the image forming means forms the mark at the leading position.

[0051] <Configuration 8> 5. The image processing device according to any one of configurations 2 to 4, further comprising a detection means that is installed in accordance with the position where the mark is formed on the transparent substrate and reads the transparent substrate to obtain the luminance value.

[0052] <Configuration 9> The image processing device according to configuration 6, wherein the calculation means increases the distance as the transport of the transparent substrate progresses if the luminance value acquired by the acquisition means continues to be within the allowable range.

[0053] <Configuration 10> 5. The image processing device according to any one of configurations 2 to 4, wherein the determining means determines the position of the mark when the distance reaches a threshold value set based on the size of the mark.

[0054] <Configuration 11> further comprising a downstream image forming unit disposed downstream of the image forming unit and having an ink different from the white ink; the subsequent-stage image forming means has, as the different ink, at least one ink of a color selected from cyan, magenta, and yellow, The image processing device according to configuration 3, wherein the subsequent image forming means forms an image based on a print job in at least one color of the cyan, magenta, and yellow in an area different from an area where the mark is present.

[0055] <Configuration 12> The image processing device according to configuration 11, characterized in that the subsequent image forming means specifies the different area as an image forming area in which an image based on the print job is formed based on the position of the mark determined by the determination means.

[0056] <Configuration 13> 13. The image processing device according to configuration 12, wherein the subsequent image forming means, when identifying the different area as the image forming area, starts forming the image based on the print job in the image forming area.

[0057] <Configuration 14> an acquisition step of acquiring a luminance value obtained by reading a transparent substrate conveyed by a conveying means provided in a printing device that prints an image for each page, the transparent substrate having a mark indicating the top position of the page already printed thereon; a calculation step of calculating a distance over which the transparent substrate is transported by the transport means while the luminance value acquired by the acquisition step is within a certain range; a determining step of determining a position of the mark on the transparent substrate based on the distance calculated in the calculating step; An image processing method comprising:

[0058] <Configuration 15> 15. A program for causing a computer to execute each step of the image processing method according to claim 14. [Explanation of symbols]

[0059] 100 Image forming system 115 2nd printing device 116 1st printing device 120 Mark detection sensor 204 Control Unit

Claims

1. an acquisition unit for acquiring a luminance value obtained by reading a transparent substrate conveyed by a conveyance unit included in a printing device that prints an image for each page, the transparent substrate having a mark indicating the top position of the page already printed thereon; a calculation means for calculating a distance over which the transparent substrate is transported by the transport means while the luminance value acquired by the acquisition means is within a certain range; a determining means for determining a position of the mark on the transparent substrate based on the distance calculated by the calculating means; An image processing device comprising:

2. 2. The image processing device according to claim 1, wherein the determining unit determines that the luminance value acquired by the acquiring unit remains within the certain range when the luminance value continues to be within an allowable range of fluctuation of the luminance value.

3. a transparent backing paper is releasably attached to the transparent substrate; 3. The image processing apparatus according to claim 2, further comprising an image forming unit having white ink and forming the mark on the transparent substrate with the white ink.

4. a transparent backing paper is releasably attached to the transparent substrate; 3. The image processing device according to claim 2, further comprising an image forming unit having ink of at least one color selected from cyan, magenta, and yellow, and forming the mark on the transparent substrate with ink of at least one color selected from cyan, magenta, and yellow.

5. 4. The image processing apparatus according to claim 2, wherein the transport means transports roll paper as the transparent substrate.

6. The image processing device according to any one of claims 2 to 4, characterized in that the calculation means starts calculating the distance when the brightness value acquired by the acquisition means is within a range between a predetermined first threshold and a second threshold that is lower than the first threshold.

7. 5. The image processing apparatus according to claim 3, wherein the image forming means forms the mark at the leading position.

8. 5. The image processing device according to claim 2, further comprising a detection means that is installed in alignment with the position where the mark is formed on the transparent substrate, and that reads the transparent substrate to obtain the luminance value.

9. 7. The image processing device according to claim 6, wherein the calculation means increases the distance as the transport of the transparent substrate progresses if the brightness value acquired by the acquisition means continues to be within the allowable range.

10. 5. The image processing device according to claim 2, wherein the determining means determines the position of the mark when the distance reaches a threshold value set based on the size of the mark.

11. further comprising a downstream image forming unit disposed downstream of the image forming unit and having an ink different from the white ink; the subsequent-stage image forming means has, as the different inks, ink of at least one color selected from cyan, magenta, and yellow, 4. The image processing device according to claim 3, wherein the subsequent image forming means forms an image based on a print job in at least one color selected from the group consisting of cyan, magenta, and yellow in an area different from an area where the mark is present.

12. 12. The image processing apparatus according to claim 11, wherein the subsequent image forming means specifies the different area as an image forming area in which an image based on the print job is to be formed, based on the position of the mark determined by the determining means.

13. 13. The image processing apparatus according to claim 12, wherein, when the subsequent-stage image forming unit specifies the different area as the image forming area, the subsequent-stage image forming unit starts forming the image based on the print job in the image forming area.

14. an acquisition step of acquiring a luminance value obtained by reading a transparent substrate conveyed by a conveying means provided in a printing device that prints an image for each page, the transparent substrate having a mark indicating the top position of the page already printed thereon; a calculation step of calculating a distance over which the transparent substrate is transported by the transport means while the luminance value acquired by the acquisition step is within a certain range; a determining step of determining a position of the mark on the transparent substrate based on the distance calculated in the calculating step; An image processing method comprising:

15. A program for causing a computer to execute each step of the image processing method according to claim 14.

Images