Image forming apparatus, image forming method, and program

Abstract

This allows for printing timing marks in a more suitable position relative to the sensor, and also reduces the effort required from the user. [Solution] A mark and a sensor position identification pattern including a first pattern and a second pattern are printed on a printing medium for printing an image. The sensor position identification pattern on the transported printing medium is detected by a sensor that detects the mark. The position of the sensor is determined based on the difference in the detection timing of the first pattern and the second pattern. The position where the mark is printed is determined based on the determined position of the sensor.

Description

Technical Field

[0001] The present invention relates to an image forming apparatus, an image forming method, and a program.

Background Art

[0002] Conventionally, for printing paper (continuous printing paper) for continuous printing, a timing mark for notifying the position of the base layer is printed in a first printing unit, and the timing mark is detected in a second printing unit to print an image on the base layer. A printing apparatus is known. Also known is a printing method called overprinting in which printing is performed using continuous printing paper on which the base layer has been previously printed by different printing machines. In overprinting, additional printing is performed in response to detection of a timing mark printed on the continuous printing paper. Similarly, an image forming apparatus including an inspection apparatus that inspects an image in response to detection of a timing mark for notifying the position of the image and the image, and a processing apparatus that performs processing such as cutting is known.

[0003] It is also known that the position of continuous printing paper shifts in the direction perpendicular to conveyance (lateral shift) due to meandering during conveyance. From such a perspective, in Patent Document 1, techniques have been proposed to print a mark of sufficient size to prevent a reading error of a timing mark, and to detect a timing mark and detect meandering of continuous printing paper. Also, in order to prevent an error when detecting a timing mark, a technique has been proposed to improve the accuracy of the image forming position from the difference in detection timing using two timing patterns (Patent Document 2). In addition, a technique has been proposed to print not only a timing mark but also a mark that can be provided with information such as a barcode or a QR code (registered trademark) and link the results at the time of inspection (Patent Document 3).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

[0005] However, Patent Documents 1, 2, and 3 describe a printing device detecting a printed mark so that a subsequent device can perform additional printing, or an inspection device or processing machine attached to the printing device similarly detects the mark and operates accordingly. In other words, it is necessary to pre-position the sensor that detects the mark to the area where the mark will pass. Therefore, there is a challenge in that the user must align the marks, or the sensor position must be adjusted using a mechanical mechanism that allows the system to change the sensor position. In addition, when overprinting, the user must move the sensor to match the position of the timing marks on the pre-printed continuous printing paper, and then return the sensor position to its original position when performing normal printing after printing. In this case, fine adjustments by the user are difficult, and there is a challenge in that errors occur due to motor deterioration over time when moving the sensor position by a mechanical mechanism.

[0006] The present invention aims to enable the printing of timing marks at a more suitable position on the sensor and to reduce the effort required from the user. [Means for solving the problem]

[0007] To achieve the object of the present invention, for example, an image forming apparatus according to one embodiment comprises the following configuration: a first printing means for printing a mark and a sensor position identification pattern including a first pattern and a second pattern on a printing medium for printing an image; a detection means for detecting the sensor position identification pattern on the conveyed printing medium using a sensor for detecting the mark; a identification means for identifying the position of the sensor based on the difference in the timing of detection of the first pattern and the second pattern; and a determination means for determining the position in which the first printing means prints the mark based on the identified position of the sensor. [Effects of the Invention]

[0008] This allows for printing timing marks in a more suitable position relative to the sensor, and also reduces the effort required from the user. [Brief explanation of the drawing]

[0009] [Figure 1] A diagram showing an example of the configuration of a system including an image forming apparatus. [Figure 2] A block diagram showing an example of the functional configuration of an image forming apparatus. [Figure 3] A flowchart showing an example of processing by the image forming apparatus according to Embodiment 1. [Figure 4] A diagram showing an example of roll paper with a specific pattern printed on it using an image forming apparatus. [Figure 5] A diagram showing an example of roll paper printed with specific patterns for different mark sensors. [Figure 6] A flowchart showing an example of processing by the image forming apparatus according to Embodiment 2. [Figure 7] A diagram illustrating printing by an image forming apparatus according to Embodiment 2. [Figure 8] A flowchart showing an example of processing by the image forming apparatus according to Embodiment 3. [Figure 9] A diagram illustrating printing by an image forming apparatus according to Embodiment 3. [Modes for carrying out the invention]

[0010] The embodiments will be described in detail below with reference to the attached drawings. Note that the following embodiments do not limit the invention as defined in the claims. While the embodiments describe multiple features, not all of these features are essential to the invention, and the features may be combined in any way. Furthermore, in the attached drawings, identical or similar configurations are given the same reference numerals, and redundant descriptions are omitted.

[0011] [Embodiment 1] Figure 1 shows an example of the system configuration of a system including an image forming apparatus according to this embodiment. The image forming apparatus 100 is an apparatus that forms an image on continuous printing paper (hereinafter referred to as roll paper) 111 capable of continuous image formation used in this embodiment. The image forming apparatus 100 according to this embodiment consists of a paper feeder 104 for transporting the roll paper 111, a white printing unit 116 for performing white printing, a color printing unit 115 for printing basic colors or spot colors, a winding device 105 for winding the roll paper 111, and an operation display unit (UI operation panel) 101.

[0012] The paper feeder 104 is a device that supplies roll paper 111 to the image forming apparatus 100. The paper feeder 104 rotates the paper core of the roll paper 111 around the rotation axis 117, thereby transporting the roll paper 111 wound on the paper core towards the image forming apparatus 100 at a constant speed via multiple rollers (conveyor rollers, paper feed rollers, etc.).

[0013] The take-up device 105 is a device that winds the roll paper 111 conveyed from the image forming device 100 around a paper tube in a roll shape. The take-up device 105 rotates around the rotation shaft 118 and winds the roll paper 111 conveyed to the paper tube around the rotation shaft 118 at a constant speed as roll paper (product) 111 via a plurality of rollers (for example, a conveyance roller or a paper discharge roller). As shown in FIG. 1, for example, the take-up device 105 can hold the roll paper 111 in a roll shape by winding it around the paper tube of the rotation shaft 118.

[0014] Before printing starts, the roll paper 111 is passed from the paper feeding device 104 to the take-up device 105. For example, first, the roll paper 111 is set in the paper feeding device 104, and the leading end of the roll paper 111 is passed over the oblique light correction device 110. Next, the roll paper 111 passes under the printing device 103 of the white printing section 116. Further, the roll paper 111 passes under the drying device 112, and then passes over the cooling devices 113 and 114. Next, the roll paper 111 passes under the mark sensor 120 of the color printing section 115, under the printing device 102, under the drying device 106, and over the cooling devices 108 and 109 in sequence. Then, the roll paper 111 passes through the connection scanner device 107 and is wound around the rotation shaft 118 of the take-up device 105.

[0015] Here, the printing device 102 is a device that prints a printed image (corresponding to a print job) on a printing medium. On the other hand, the printing device 103 is a device that prints a mark (timing mark) for controlling the printing timing and a predetermined sensor position specifying pattern (specifying pattern) for specifying the position of the mark sensor 120 that detects the timing mark before the printing by the printing device 102. Here, the mark sensor is a sensor that monitors a predetermined position of the conveyed printing medium and notifies the image forming apparatus 100 that the detection is successful when printing of a color within a predetermined range set as a detection target passes through the predetermined position. Here, the timing mark and the specifying pattern are printed in a color within a predetermined range detected by the corresponding mark sensor. Also, when there are a plurality of mark sensors (such as the mark sensor 120 and the mark sensor 122), a predetermined color range to be detected in each of them is set. The specifying pattern will be described later with reference to FIG. 3.

[0016] The image forming system according to the present embodiment may be connected to a device (post-processing device) that performs inspection, processing, or both of the inspection and processing of the product as post-processing. In the example of FIG. 1, a post-processing device 121 that performs inspection, processing, or both of the inspection and processing after printing is connected between the color printing unit 115 and the winding device 105. Hereinafter, the inspection, processing, or both of the inspection and processing of the product executed by the post-processing device 121 may be simply referred to as "post-processing". The roll paper 111 printed by the color printing unit 115 passes through the mark sensor 122 in the post-processing device 121, then passes through the post-processing unit 123, and is wound as a product by the winding device 105. At this time, depending on the configuration of the post-processing unit 123, post-processing as a cut paper product may be applied to the roll paper 111 before it is carried into the winding device 105.

[0017] Here, after passing the roll paper 111 through the image forming system, a print job is input to the control PC 119 of the image forming system. When the print start button is pressed on the operation display unit 101 after the print job is input, the image forming apparatus 100 starts printing.

[0018] Next, the functional configuration of the image forming system will be described in detail. Figure 2 is a block diagram showing an example of the functional configuration of the image forming apparatus 100. The image forming apparatus 100 according to this embodiment includes a paper transport 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, a paper feed control unit 208, a post-processing control unit 210, and a winding control unit 209. The paper transport unit 201 transports the roll paper 111 inside the image forming apparatus 100. For example, the paper transport unit 201 uses multiple rollers to transport the roll paper 111 transported from the paper feed device 104 to the position where the image is formed by the image forming unit 202. Then the paper transport unit 201 transports the roll paper 111, on which the image has been formed by the image forming unit 202, to the winding device 105.

[0019] The image forming unit 202 forms an image on the roll paper 111 supplied from the paper feeder 104 based on the print data that has been instructed to be output. The communication unit 203 is composed of a communication control card, such as a LAN (Local Area Network) card, and transmits and receives various data with external devices (such as personal computers) connected to a communication network such as a LAN or WAN (Wide Area Network). The control unit 204 is composed of, for example, a CPU (Central Processing Unit) and RAM (Random Access Memory). The CPU of the control unit 204 reads various programs, such as system programs or processing programs, stored in the memory unit 205, loads them into RAM, and executes various processes according to the loaded programs. For example, the control unit 204 can perform image forming processing to execute an image forming job (hereinafter simply referred to as a job) in response to a user's instruction.

[0020] The storage unit 205 is composed of, for example, a non-volatile semiconductor memory (so-called flash memory) or an HDD (Hard Disk Drive). The storage unit 205 stores various programs, including system programs and processing programs executed by the control unit 204, as well as various data necessary for the execution of these programs. The operation display unit 206 is composed of, for example, a liquid crystal display (LCD) with a touch panel, and comprises a display unit 206a and an operation unit 206b. The display unit 206a displays various information on the display screen according to display control signals input from the control unit 204. The operation unit 206b is equipped with various operation keys such as a numeric keypad or start key, accepts various input operations from the user, and outputs operation signals to the control unit 204. The operation display unit 206 is used, for example, to set partition information when executing a job. Partition information is information indicating the insertion position of partition pages to be inserted into the job in advance, used when it is necessary to sort the output of continuous printed paper that has undergone image forming processing into multiple rolls for delivery. The partition information may be generated based on any of the following conditions that can be arbitrarily set by the user: the number of prints, the number of copies, the print length, the print weight, or the print diameter.

[0021] Next, the operation when image forming processing is performed on roll paper in the image forming apparatus 100 will be described. First, the user creates job data in an external device, sets the job's print settings and the number of rolls to be delivered, and transmits this information to the image forming apparatus 100 via a communication network. The control unit 204 of the image forming apparatus 100 receives the job data transmitted from the external device, along with a job ticket containing the job's print settings and the number of rolls to be delivered, via the communication unit 203.

[0022] Furthermore, the control unit 204 generates information indicating the timing of the start of printing based on the position at which the printing device 102 starts printing relative to the position of the mark sensor 120. Then, in response to the mark sensor 120 detecting a timing mark, the control unit 204 starts printing based on the generated information indicating the timing of the start of printing.

[0023] The inspection unit 207 is a device that verifies whether printing on the printing medium is complete without printing defects (including ejection defects). In the following explanation, we will describe the inspection as being performed on ejection defects as a type of printing defect, but this is not limited to any other type of printing defect that can be detected by similar general printing defect inspection techniques. For example, the inspection unit 207 prints a pattern for ejection defect inspection and reads it with a scanner to generate an inspection image that serves as the standard for inspection. The inspection unit 207 then compares the printed image with the inspection image to check for ejection defects in the printed image, and if an ejection defect is detected, it can stop the image forming apparatus. Inspection of ejection defects using the inspection image can be performed using any general inspection technique. The inspection by the inspection unit 207 can employ any method, such as using an inspection pattern read by a scanner as the inspection image, directly reading the printed image with a camera or scanner for inspection, or monitoring the ejection status from the nozzle to detect ejection defects.

[0024] The post-processing control unit 210 controls the execution of post-processing by the post-processing device 121. The processing control process by the post-processing control unit 210 is described below. The post-processing control unit 210 generates information indicating the timing of the start of post-processing based on the position at which the post-processing device 121 starts post-processing relative to the position of the mark sensor 120. Then, in response to the mark sensor 120 detecting a timing mark, the post-processing control unit 210 starts post-processing based on the generated information indicating the timing of the start of post-processing. The processing by the post-processing control unit 210 may be executed by a control unit different from the post-processing control unit 210 that communicates with the image forming apparatus 100.

[0025] Figure 3 is a flowchart showing an example of the processing performed by the image forming apparatus 100 according to this embodiment. The image forming apparatus 100 according to this embodiment determines the printing position of the marks to be printed during job printing by performing an operation to identify the position of the mark sensor before performing job-specific printing (job printing). In this embodiment, an example in which subsequent printing and post-processing are performed in response to the detection of a timing mark will be described.

[0026] The image forming apparatus 100 prints a predetermined pattern (identification pattern) on the printing medium for identifying the position of the mark sensor 120. The identification pattern according to this embodiment includes a first pattern and a second pattern, and the position of the mark sensor 120 is identified according to the difference in detection timing between the first pattern and the second pattern. Here, the first pattern is a linear pattern perpendicular to the transport direction of the printing medium used as a reference, and the second pattern is a linear pattern oblique to determine the time difference with respect to the detection timing of the first pattern.

[0027] In the following explanation, the first pattern is assumed to be a linear pattern perpendicular to the transport direction of the printing medium, as described above, and the second pattern is assumed to be a linear pattern not parallel to the first pattern. However, the patterns constituting the specific pattern are not particularly limited in this way, as long as the difference in detection timing between the first and second patterns changes depending on the y-coordinate (coordinate axes will be described later) of the position of the mark sensor. In particular, the first pattern may be a linear pattern not perpendicular to the transport direction of the printing medium. Also, the first and second patterns may be curved patterns rather than straight lines.

[0028] In S300, the image forming unit 202 controls the printing device 103 to print a specific pattern. Here, the image forming unit 202 prints a timing mark that controls the timing of the start of printing of the printing device 102, which will perform printing following the printing device 103.

[0029] In S301, the inspection unit 207 controls the mark sensor 120 to read (detect) a specific pattern from the printed medium. In S302, the storage unit 205 records the timing when the mark sensor 120 read the specific pattern.

[0030] In S303, the control unit 204 returns to S301 if the process of reading the identification pattern in the preceding S301 was the first (initial) process. Otherwise, the process proceeds to S304. In this embodiment, the identification pattern consists of at least two linear patterns, so it will be read by the mark sensor 120 at least twice during the transport of the printing medium. Here, the following explanation assumes that S304 is executed after S301 to S303 have been repeated twice.

[0031] In S304, the control unit 204 calculates the difference between the timing recorded in the first S302 and the timing recorded in the second S302. That is, the difference between the timing when the first pattern was detected and the timing when the second pattern was detected is calculated.

[0032] In this embodiment, the position of the mark sensor is determined based on the difference in the detection timing of the first pattern and the second pattern. The control unit 204 can determine the position of the mark sensor perpendicular to the transport direction of the printing medium based on the difference in the detection timing of the first pattern and the second pattern. For example, a table showing the correspondence between such timing differences and the position of the mark sensor perpendicular to the transport direction of the printing medium may be stored in advance, and the control unit 204 may acquire the above-mentioned perpendicular position based on the calculated timing difference.

[0033] Here, by printing multiple sets of specific patterns (i.e., the first pattern and the second pattern) and calculating the difference multiple times, and then calculating the difference in detection timing between the first pattern and the second pattern based on these calculations, it becomes possible to more accurately pinpoint the position of the mark sensor. From this perspective, in this embodiment, the above-mentioned difference calculation may be performed multiple times, and a statistical quantity such as the average may be used as the difference. In Figure 3, the first pattern and the second pattern are printed multiple times (N times, which can be set arbitrarily), and the timing difference calculated N times is used when processing S305. If the set of the first pattern and the second pattern is printed only once, S305 is omitted.

[0034] In S305, the control unit 204 determines whether the execution of the process in S304 is less than N times. If it is less than N times, the process returns to S301; otherwise, the process proceeds to S306.

[0035] In S306, the control unit 204 identifies the position of the mark sensor 120 based on the difference calculated in S304. For example, the control unit 204 may identify the position of the mark sensor 120 by comparing the roll paper transport speed with the difference calculated in S304. Alternatively, the control unit 204 may pre-measure the difference in a reference timing and compare the difference calculated in S304 with the reference to identify the position of the mark sensor 120 using the position corresponding to the reference. If S305 is executed and the timing difference is calculated two or more times, the average or intermediate value of the multiple timing differences may be used in S306. The control unit 204 then determines the position for printing the timing mark based on the identified position of the mark sensor 120 and terminates the process shown in Figure 6. Here, the control unit 204 determines the position for printing the timing mark to be a position where the identified mark sensor 120 passes directly above it (during roll paper transport). In other words, the control unit 204 determines the position for printing the timing mark when the printing medium is being transported, such that the position perpendicular to the transport direction of the printing medium coincides with the position of the mark sensor 120 whose position has been identified and the timing mark to be printed.

[0036] In the following, when evaluating the coordinates (x,y) in a plan view of a roll of paper as shown in Figure 4, which will be described later, the axis in the transport direction will be represented as the x-axis, and the axis perpendicular to the transport direction will be represented as the y-axis. Here, the control unit 204 can set the position for printing the timing mark to have the y-coordinate as the position through which the mark sensor passes, and the x-coordinate as a predetermined coordinate (for example, a coordinate value corresponding to 1 cm in distance on the paper surface) away from the x-coordinate of the trailing end of the specific pattern.

[0037] Figure 4 shows an example of a roll of paper in which N used in S305 is set to 2 and the specific pattern is printed twice. In the example in Figure 4, the image forming apparatus 100 prints the specific pattern 402 in an area 401 outside the image forming area where the print image is printed on the roll of paper 400. In Figure 4, the mark sensor 120 is shown as mark sensor 404. Here, the mark sensor 404 is assumed to be located in a position where it can read the specific pattern 402 (in this case, the upper part of area 401 when the roll of paper is transported), although its exact position is unknown.

[0038] The identification pattern 402 consists of at least two linear patterns (a first pattern and a second pattern). The identification pattern is arranged such that the difference 403 in the detected timing between the first pattern and the second pattern differs depending on the position of the mark sensor 404. In the example in Figure 4, the first pattern is a linear pattern perpendicular to the direction of transport of the roll paper, and the second pattern is a linear pattern not parallel to the first pattern. With this arrangement, the difference 403 becomes larger as the mark sensor 404, which is placed on the region 401, gets closer to the edge of the roll paper. In the example in Figure 4, the identification pattern that is printed twice has a common shape, but the shape of the first identification pattern and the second identification pattern may be different.

[0039] The number of mark sensors is not particularly limited, and multiple mark sensors may be provided. If multiple mark sensors exist, a specific pattern corresponding to each of them may be printed. Figure 5 shows an example of a roll of paper with specific patterns corresponding to each of the multiple mark sensors printed on it.

[0040] Identification pattern 500 is a pattern for identifying the position of mark sensor 120 as a first mark sensor, and is printed in a color within the range that mark sensor 120 can recognize. Identification pattern 501 is a pattern for identifying the position of mark sensor 122 as a second mark sensor, and is printed in a color within the range that mark sensor 122 can recognize. Here, it is assumed that mark sensor 122 does not detect objects of the color of identification pattern 500 (here, the color of identification pattern 500 is considered to be outside the range that the mark sensor can recognize). Here, identification pattern 500 is printed by printing device 103, and identification pattern 501 is printed by printing device 102.

[0041] The printing of the identification pattern 501 may be performed in synchronization with other processes of the image forming apparatus 100, for example, when the mark sensor 120 detects the identification pattern 500, or when the count of drive pulses reaches a predetermined value. Such processing makes it possible to reliably print the identification pattern 501 close to the printed image. On the other hand, the printing of the identification pattern 501 may not be performed in such a synchronized manner, and the identification pattern may be executed as an independent process. Furthermore, in order to improve the accuracy of determining the position of the mark sensor, multiple copies of each identification pattern may be printed, and the position of the mark sensor may be determined using these identification patterns. In that case, the printing order of the identification pattern 500 and the identification pattern 501 is not limited to that shown in Figure 5.

[0042] This process prints a specific pattern containing both a first and a second pattern, and the position of the mark sensor can be determined based on the difference in detection timing between the first and second patterns. Furthermore, the position for printing the timing mark can be determined based on the determined position of the mark sensor. Therefore, it becomes possible to print the timing mark in a more appropriate position relative to the sensor. As a result, false detections caused by meandering of the paper roll can be reduced, and the user's effort can be reduced by eliminating the need for precise timing mark positioning. In addition, it is possible to reduce ink usage by making the printed timing marks smaller.

[0043] In this explanation, we described an example in which the position of a mark sensor is determined based on the difference in detection timing in a specific pattern. However, based on such a difference in detection timing, the positions of objects other than the mark sensor used for controlling the start of printing of the printed image may also be additionally determined. For example, based on such a difference in detection timing, the position of a mark sensor that reads marks to which various information such as printing information or inspection information is attached may be further determined. Also, for example, as explained with reference to Figure 5, a specific pattern for controlling the start timing of post-processing by the post-processing device 121 may be additionally printed, and the position of the mark sensor used for controlling the start timing of post-processing may be determined based on the detection timing of the specific pattern.

[0044] [Embodiment 2] The image forming apparatus according to Embodiment 1 identified the position of the mark sensor using a specific pattern. In addition to the processing in Embodiment 1, the image forming apparatus according to this embodiment rewinds the roll paper at the position where the timing marks are to be printed and performs the main printing (printing of the image). The image forming apparatus 100 according to this embodiment has the same configuration as that in Embodiment 1 and can perform the same processing, so redundant explanations will be omitted. Below, we will explain the processing performed by the image forming apparatus that differs from that described in Embodiment 1.

[0045] Figure 6 is a flowchart showing an example of the processing performed by the image forming apparatus 100 according to this embodiment. In this case, the image forming apparatus 100 skips reading the identification pattern used to identify the position of the mark sensor when performing the main print after rewinding the roll paper.

[0046] The process shown in Figure 6 is the same as that shown in Figure 3 of Embodiment 1, except that steps S601 to S607, which follow S306, are further executed; therefore, redundant explanations will be omitted.

[0047] In S601, the storage unit 205 records the number of sets of specific patterns detected in S301. Furthermore, the storage unit 205 also records the total number of patterns included in a single specific pattern.

[0048] This explanation assumes there is only one mark sensor; however, if there are multiple mark sensors, each will be processed separately. For example, if there are mark sensors 120 and 122, the number of sets of specific patterns will be recorded for each of them.

[0049] In step S602, the paper transport unit 201 unwinds the roll paper 111. For example, the paper transport unit 201 can unwind the roll paper 111 to the position where the printing device 103 starts printing, at a coordinate immediately behind the x-coordinate of the trailing end of the specific pattern printed by the printing device 103 (for example, 1 cm behind the trailing end). Alternatively, for example, if the printing is performed by the printing device 102 instead of the printing device 103, the paper transport unit 201 may unwind the roll paper 111 to the position where the printing device 102 performs the actual printing.

[0050] In S603, the image forming unit 202 controls the printing device 103 or the printing device 102 to print a timing mark. Here, the coordinates of the timing mark printing position are such that the y-coordinate is the position through which the mark sensor 120 passes, and the x-coordinate is the coordinate immediately behind and behind the rear end of the identification pattern in the transport direction. In the following description, it is assumed that the timing mark is printed by the printing device 103, and the main printing by the printing device 102 is performed when the mark sensor 120 detects the timing mark.

[0051] In S604, the inspection unit 207 controls the mark sensor to perform detection processing from the printing medium. Next, depending on whether the inspection unit 207 has successfully detected a mark from the printing medium, it increases the detection count (initial value is 0) by 1 and proceeds to S605. Here, a specific pattern is printed before the timing mark, and the specific pattern is detected by the mark sensor before the timing mark is detected. Therefore, in this embodiment, the image forming apparatus 100 performs print control through processing S605 to S607 so that it does not start the main printing if the mark sensor detects the specific pattern, and starts the main printing only when the timing mark is detected.

[0052] In S605, the control unit 204 determines whether the number of detections by the mark sensor in S604 is M or less. If the number of detections by the mark sensor is M or less, the detected items in S604 are considered to be specific patterns and processing returns to S604. If the number of detections by the mark sensor is greater than M, the detected items in S604 are considered to be timing marks and processing proceeds to S606. Here, M is the number obtained by multiplying the number of sets of specific patterns recorded in S601 by the total number of patterns contained in one specific pattern. For example, if the number of sets of specific patterns to be printed is 2 and the total number of patterns contained in one specific pattern is 2, then M will be 4.

[0053] In S606, the control unit 204 executes the main print operation in response to the detection of a timing mark in S604. Here, the control unit 204 controls the printing device 102 to execute the main print operation.

[0054] In S607, the control unit 204 determines whether there are still pages to print. If printing of all pages has been completed in the preceding S606, the process in Figure 6 ends. Otherwise, the number of detections by the mark sensor is reset to its initial value, and the process returns to S604, where the printing process continues.

[0055] In this explanation, it is assumed that the printing device 103 prints a timing mark, and the printing device 102 performs the main printing in response to the mark sensor 120 detecting the timing mark. However, this is just one example; for example, the printing device 102 may print a timing mark, and the post-processing unit 123 may perform post-processing in response to the mark sensor 122 detecting the timing mark.

[0056] Figure 7 shows an example of a roll of paper that has been printed with a specific pattern twice before the main print. In this figure, a timing mark 703 is printed after the two specific patterns 701 and 702. Here, the printing device 103 prints the timing mark 703 and the background image 704. Then, in response to the mark sensor 120 detecting the timing mark 703, the printing device 102 prints the upper image 705 on top of the background image 704.

[0057] This process allows the roll paper 111 to be rewound after the position of the mark sensor has been identified, and then the main print job can be performed. If rewinding is not performed, there would be waste paper in the roll paper that was transported for the process of identifying the sensor position, but the rewinding process makes it possible to use such waste paper for printing as well. Therefore, by using the roll paper efficiently through rewinding, and by skipping the detection of identification patterns by the mark sensor and starting printing when a timing mark is detected, normal printing can be performed even after rewinding.

[0058] In this example, similar to Embodiment 1, the position of the mark sensor is determined based on the difference in detection timing in the specific pattern. However, based on such a difference in detection timing, the positions of objects other than the mark sensor used for controlling the start of printing of the printed image may also be additionally determined. For example, based on such a difference in detection timing, the position of the mark sensor that reads marks to which various information such as printing information or inspection information is attached may be further determined.

[0059] [Embodiment 3] The image forming apparatus according to Embodiment 2 rewinds the roll paper at the position where the timing mark is to be printed, skips the detection of the specific pattern, and performs the main printing in response to the detection of the timing mark. The image forming apparatus according to this embodiment performs the main printing when a specific pattern is detected, rather than when a timing mark is detected (i.e., the specific pattern is used as the timing mark). The image forming apparatus 100 according to this embodiment has the same configuration as that in Embodiment 2 and can perform the same processing, so redundant explanations will be omitted. Below, we will explain the processing performed by the image forming apparatus that differs from that described in Embodiment 2.

[0060] Figure 8 is a flowchart showing an example of the process performed by the image forming apparatus 100 according to this embodiment. The process shown in Figure 8 is the same as that shown in Figure 6 of Embodiment 2, except that S801 to S805 are performed instead of S605, so redundant explanations are omitted.

[0061] In S604, the inspection unit 207 controls the mark sensor to perform detection processing from the printing medium, similar to Embodiment 2, and after increasing the detection count by 1, proceeds to S801. In this embodiment, a specific pattern is printed before the timing mark, but in this embodiment, even if the mark sensor detects the first pattern included in the specific pattern before the timing mark, the main printing is performed as if the timing mark had been detected.

[0062] In this explanation, we assume that the main printout is executed when the mark sensor detects the first pattern. However, this example is not limited to this one, as long as the main printout is executed at the timing of detection of a specific pattern, such as when the second pattern is detected.

[0063] In S801, the control unit 204 determines whether the number of detections by the mark sensor in S604 is a predetermined value. Here, the predetermined value is set to a value less than or equal to the total number of patterns included in one specific pattern. If the number of detections by the mark sensor in S604 is a predetermined value, the process proceeds to S802; otherwise, the process returns to S604. In this example, this predetermined value is treated as 1, but it may be any other value, and multiple values ​​may be set as the predetermined value. If multiple values ​​are set as the predetermined value, S801 to S802 are repeated until the number of executions corresponds to the number of values.

[0064] In S802, the control unit 204 executes the main print operation in response to the detection of a predetermined value-number pattern of the identification pattern in S604. Here, the control unit 204 controls the printing device 102 to execute the main print operation.

[0065] In S803, the inspection unit 207 controls the mark sensor to perform detection processing from the printing medium, similar to S604, and after increasing the detection count by 1, proceeds to S804. S803 is performed in parallel with the main printing process in S802.

[0066] In S804, the control unit 204 determines whether the number of detections by the mark sensor in S803 is M or less, similar to S605 in Embodiment 2. If the number of detections by the mark sensor is M or less, the detections in S803 are considered to be specific patterns and the process returns to S803. If the detections by the mark sensor are more than M, the detections in S803 are considered to be timing marks and the process proceeds to S805.

[0067] In S805, the control unit 204, in response to the detection of a timing mark in S803, executes the main print and proceeds to S607. Here, the control unit 204 controls the printing device 102 to execute the main print.

[0068] S607 is executed in the same manner as in Embodiment 2, and if there are still pages to print, the number of detections by the mark sensor is reset to the initial value and processing starts again from S604.

[0069] Figure 9 shows an example of a roll of paper that has undergone printing using the image forming apparatus according to this embodiment. Here, Figure 9 shows a roll of paper that has undergone printing after the set of specific patterns and timing marks has been printed twice. Printing on the roll of paper shown in Figure 9 is performed in the same manner as shown in Figure 7, except that the printing of the print image is performed in response to the detection of specific patterns 901 and 902. Here, when the mark sensor 120 detects specific pattern 901, which is the first pattern included in the first set of specific patterns, the printing device 102 prints image 903. Also, when the specific pattern 902, which is the first pattern included in the second set of specific patterns, is detected, the printing device 102 prints an image.

[0070] This process allows printing to be performed not only when the mark sensor is detected but also when a specific pattern is detected, while rewinding the roll paper 111 after identifying the position of the mark sensor. Therefore, it is possible to use the roll paper more efficiently while performing normal printing even after rewinding.

[0071] In this example, similar to Embodiment 1, the position of the mark sensor is determined based on the difference in detection timing in the specific pattern. However, based on such a difference in detection timing, the positions of objects other than the mark sensor used for controlling the start of printing of the printed image may also be additionally determined. For example, based on such a difference in detection timing, the position of the mark sensor that reads marks to which various information such as printing information or inspection information is attached may be further determined.

[0072] The disclosures herein include the following image forming apparatus, image forming method, and program. (Item 1) A first printing means for printing a mark, and a sensor position identification pattern including a first pattern and a second pattern, on a printing medium for printing an image, A detection means for detecting the sensor position identification pattern on the transported printing medium using a sensor that detects the mark, A means for determining the position of the sensor based on the difference in the timing of detection of the first pattern and the second pattern, A determination means that determines the position in which the mark is printed by the first printing means based on the identified position of the sensor, An image forming apparatus comprising: (Item 2) The image forming apparatus according to item 1, characterized in that the first pattern is a linear pattern and the second pattern is a linear pattern that is not parallel to the first pattern. (Item 3) The first printing means prints multiple sets of the sensor position identification pattern, The image forming apparatus according to item 1, characterized in that the identifying means identifies the position of a sensor that detects a mark based on the difference in the timing of detection of the first pattern and the second pattern in each of the multiple printed sensor position identification patterns. (Item 4) The image forming apparatus according to item 1, characterized in that the identifying means determines the position of the sensor that detects the mark in a direction perpendicular to the transport direction of the printing medium based on the difference in the timing of detection of the first pattern and the second pattern. (Item 5) The image forming apparatus according to item 4, characterized in that the determination means determines the position for printing the mark at a position perpendicular to the transport direction of the printing medium when the printing medium is transported, such that the position of the sensor and the mark to be printed coincide. (Item 6) A recording means for recording the total number of patterns included in the sensor position identification pattern, A rewinding means for rewinding the position of the printing medium where the position for printing the aforementioned mark has been determined, The system further comprises a second printing means that prints a printed image onto the rewound printing medium in response to the sensor detecting the mark printed by the first printing means on the printing medium, The image forming apparatus according to item 1, characterized in that the detection means determines that the mark has been detected when the number of detections by the sensor exceeds the total number of patterns. (Item 7) The image forming apparatus according to item 6, wherein the second printing means further prints a printed image on the printing medium when the number of detections by the sensor on the rewound printing medium becomes a predetermined value set to be less than or equal to the total number of patterns. (Item 8) A step of printing a mark, and a sensor position identification pattern including a first pattern and a second pattern, on a printing medium on which an image is printed, A step of detecting the sensor position identification pattern on the transported printing medium using a sensor that detects the mark, A step of determining the position of the sensor based on the difference in the timing of detection of the first pattern and the second pattern, A step of determining the position to print the mark based on the identified position of the sensor, An image forming method comprising: (Item 9) A program for causing a computer to function as one of the means of an image forming apparatus described in any one of items 1 through 7.

[0073] (Other examples) The present invention can also be realized by supplying a program that implements one or more of the functions of the above-described embodiments to a system or device via a network or storage medium, and by having one or more processors in the computer of that system or device read and execute the program. It can also be realized by a circuit (e.g., an ASIC) that implements one or more functions.

[0074] The invention is not limited to the embodiments described above, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, claims are attached to disclose the scope of the invention. [Explanation of symbols]

[0075] 201: Paper transport unit, 202: Image forming unit, 203: Communication unit, 204: Control unit, 205: Storage unit, 206: Operation display unit, 207: Inspection unit, 208: Paper feeding control unit, 209: Winding control unit, 210: Post-processing control unit

Claims

1. A first printing means for printing a mark and a sensor position identification pattern including a first pattern and a second pattern onto a printing medium for printing an image, A detection means for detecting the sensor position identification pattern on the transported printing medium using a sensor that detects the mark, A means for identifying the position of the sensor based on the difference in the timing of detection of the first pattern and the second pattern, A determination means that determines the position in which to print the mark by the first printing means based on the identified position of the sensor, An image forming apparatus comprising:

2. The image forming apparatus according to claim 1, characterized in that the first pattern is a linear pattern and the second pattern is a linear pattern that is not parallel to the first pattern.

3. The first printing means prints multiple sets of the sensor position identification pattern, The image forming apparatus according to claim 1, characterized in that the identifying means identifies the position of a sensor that detects a mark based on the difference in the timing of detection of the first pattern and the second pattern in each of the multiple printed sensor position identifying patterns.

4. The image forming apparatus according to claim 1, characterized in that the identifying means identifies the position of the sensor that detects the mark in a direction perpendicular to the transport direction of the printing medium based on the difference in the timing of detection of the first pattern and the second pattern.

5. The image forming apparatus according to claim 4, characterized in that the determination means determines the position for printing the mark at a position perpendicular to the transport direction of the printing medium when the printing medium is transported, such that the position of the sensor and the mark to be printed coincide.

6. A recording means for recording the total number of patterns included in the sensor position identification pattern, A rewinding means for rewinding the position of the printing medium where the position for printing the aforementioned mark has been determined, The system further comprises a second printing means that prints a printed image onto the rewound printing medium in response to the sensor detecting the mark printed by the first printing means on the printing medium, The image forming apparatus according to claim 1, characterized in that the detection means detects the mark when the number of detections by the sensor exceeds the total number of patterns.

7. The image forming apparatus according to claim 6, wherein the second printing means further prints a printed image on the printing medium when the number of detections by the sensor on the rewound printing medium becomes a predetermined value set to be less than or equal to the total number of patterns.

8. A step of printing a mark, and a sensor position identification pattern including a first pattern and a second pattern, on a printing medium on which an image is printed, A step of detecting the sensor position identification pattern on the transported printing medium using a sensor that detects the mark, A step of determining the position of the sensor based on the difference in the timing of detection of the first pattern and the second pattern, A step of determining the position to print the mark based on the identified position of the sensor, An image forming method comprising:

9. A program for causing a computer to function as one of the means of an image forming apparatus according to any one of claims 1 to 7.

Images