Image forming system, colorimetric control method, and program

Abstract

This invention provides an image forming system, a colorimetric control method, and a program that are inexpensive, produce minimal waste, and enable high-precision color measurement across the entire surface, even with a continuous-paper printing press. [Solution] An image forming system 100 comprises an image forming unit 23 that forms an image on continuous paper PM, a colorimetric unit 33 that measures the color of the image formed on the continuous paper PM by the image forming unit 23, and a transport unit (transport unit 34, etc.) that transports the continuous paper PM. The system includes a control unit 21 that controls a first operation in which the transport unit transports the continuous paper PM by a predetermined length in the transport direction and then rewinds and transports it by a predetermined length in the opposite direction of the transport direction, and a second operation in which the colorimetric unit 33 moves a predetermined distance in the width direction perpendicular to the transport direction of the continuous paper PM. The control unit 21 repeats the first and second operations until the color measurement of the image by the colorimetric unit 33 is completed.

Description

Technical Field

[0001] The present disclosure relates to an image forming system, a color measurement control method, and a program.

Background Art

[0002] Conventionally, image forming apparatuses are provided with a mechanism for guaranteeing color matching (color characteristics). Specifically, the image forming apparatus compares a color measurement value obtained by measuring the color of an image formed on a sheet with a colorimeter, with the image data of the image, and corrects a color conversion table used for image forming processing based on the comparison result. For example, a method is known in which color matching is performed by measuring the color of only one line with a fixed colorimeter while conveying a sheet.

[0003] In recent years, color matching by color measurement is similarly required even for products printed by a roll paper (continuous paper) printing machine. For example, Patent Document 1 discloses a configuration for performing color matching by measuring the color of an image printed by a roll paper printing machine.

[0004] On the other hand, in sheet-fed presses as well, a test chart for color measurement is sent before starting a job, and the entire surface of the image on the sheet is read by a colorimeter (full-surface color measurement). For example, Patent Document 2 discloses a configuration that measures the color of the entire surface of a sheet by stopping sheet conveyance, conveying the sheet by one line, and reciprocating the colorimeter in the CD direction of the sheet.

Related Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

SUMMARY OF THE INVENTION

Problem to be Solved by the Invention

[0006] However, in the configuration described in Patent Document 1, if one attempts to increase the number of colors in a single-line colorimetric measurement to achieve high-precision colorimetric measurement, the chart image becomes longer with each additional patch, resulting in increased paper waste. Furthermore, when applying the configuration described in Patent Document 2 to a roll paper printing press, it is extremely difficult to accurately stop and transport the paper at each patch interval because the paper transport drive mechanism of the roll paper printing press is a system suited for long-distance transport. Therefore, there is a problem of reduced color measurement accuracy. Another method is to measure the color of multiple rows simultaneously with multiple colorimeters, but configurations equipped with multiple colorimeters are generally expensive.

[0007] The purpose of this disclosure is to provide an image forming system, a colorimetric control method, and a program that can measure the entire surface with high accuracy, even with a continuous paper printing press, while minimizing waste and being inexpensive. [Means for solving the problem]

[0008] The invention described in claim 1 was made to achieve the above objective, An image forming system comprising: an image forming unit for forming an image on continuous paper; a colorimetric unit for measuring the color of the image formed on the continuous paper by the image forming unit; and a transport unit for transporting the continuous paper, The control unit controls a first operation in which the transport unit transports the continuous paper by a predetermined length in the transport direction and rewinds and transports it by the predetermined length in the opposite direction of the transport direction, and a second operation in which the colorimeter moves the colorimeter by a predetermined distance in the width direction perpendicular to the transport direction of the continuous paper. The control unit is characterized by repeating the first operation and the second operation until the color measurement of the image by the color measurement unit is completed.

[0009] The invention described in claim 2 is an image forming system described in claim 1, The colorimeter is characterized in that it measures the color of the image only when the continuous paper is being transported in the transport direction.

[0010] The invention described in claim 3 is an image forming system described in claim 1, The colorimeter is characterized in that it measures the color of the image both when the continuous paper is being transported in the transport direction and when it is being transported in the opposite direction to the transport direction.

[0011] The invention described in claim 4 is an image forming system described in claim 1, The predetermined distance is characterized by being a distance corresponding to the size of the colorimetric patch formed on the continuous paper.

[0012] The invention described in claim 5 is an image forming system described in claim 1, The colorimetric unit is characterized in that it starts measuring the color of the image after the transport speed of the continuous paper by the transport unit reaches a predetermined speed.

[0013] The invention described in claim 6 is an image forming system according to claim 1, The colorimeter is characterized in that it starts measuring the color of the image after the continuous paper has been transported by the transporter for a predetermined distance or time.

[0014] The invention described in claim 7 is an image forming system described in claim 1, The colorimetric unit is characterized in that its initial position is at either of the ends in the width direction of the colorimetric chart image formed on the continuous paper.

[0015] The invention described in claim 8 is an image forming system according to claim 1, The system includes a detection unit that detects a trigger patch indicating the timing for starting color measurement by the color measurement unit, The colorimeter is characterized in that it starts measuring the color of the image after a predetermined time has elapsed since the trigger patch formed on the continuous paper was detected by the detection unit.

[0016] The invention described in claim 9 is an image forming system described in claim 8, The detection unit is a first detection unit that detects a first trigger patch indicating a timing to start color measurement by the color measurement unit when the continuous paper is conveyed in the conveyance direction, a second detection unit that detects a second trigger patch indicating a timing to start color measurement by the color measurement unit when the continuous paper is conveyed in the direction opposite to the conveyance direction, comprising:

[0017] The invention according to claim 10 is the image forming system according to claim 8, in which the color measurement unit changes the predetermined time between when the continuous paper is conveyed in the conveyance direction and when the continuous paper is conveyed in the direction opposite to the conveyance direction.

[0018] The invention according to claim 11 is a color measurement control method for an image forming system, the image forming system comprising: an image forming unit that forms an image on continuous paper; a color measurement unit that measures the color of the image formed on the continuous paper by the image forming unit; and a conveyance unit that conveys the continuous paper, the method comprising a control step of controlling a first operation in which the conveyance unit conveys the continuous paper by a predetermined length in the conveyance direction and rewinds and conveys the continuous paper by the predetermined length in the direction opposite to the conveyance direction, and a second operation in which the color measurement unit is moved by a predetermined distance in the width direction orthogonal to the conveyance direction of the continuous paper, wherein in the control step, the first operation and the second operation are repeated until the color measurement of the image by the color measurement unit is completed.

[0019] The invention according to claim 12 is a non-transitory computer-readable medium storing a program that causes a computer of an image forming system, the image forming system comprising: an image forming unit that forms an image on continuous paper; a color measurement unit that measures the color of the image formed on the continuous paper by the image forming unit; and a conveyance unit that conveys the continuous paper, to function as a control unit that controls a first operation in which the conveyance unit conveys the continuous paper by a predetermined length in the conveyance direction and rewinds and conveys the continuous paper by the predetermined length in the direction opposite to the conveyance direction, and a second operation in which the color measurement unit is moved by a predetermined distance in the width direction orthogonal to the conveyance direction of the continuous paper. The program is characterized in that the control unit repeats the first operation and the second operation until color measurement of the image by the color measurement unit is completed. ADVANTAGEOUS EFFECTS OF INVENTION

[0020] According to the present disclosure, even with a continuous paper printing machine, it is possible to perform color measurement over the entire surface with high accuracy at low cost while reducing waste sheets. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] [Figure 1] It is a diagram showing a schematic configuration of an image forming system according to the present embodiment. [Figure 2] It is a diagram showing a schematic configuration of an image forming apparatus. [Figure 3] It is a functional block diagram showing the control structure of the image forming apparatus and the image reading apparatus. [Figure 4] It is a flowchart showing an example of control of the image forming system according to the present embodiment. [Figure 5] It is a diagram showing an example of a state of reading all patches over a plurality of columns and a plurality of rows of a color measurement chart image printed on continuous paper. [Figure 6] It is a diagram showing an example of a state in which a detection unit detects a trigger patch formed on continuous paper conveyed in the conveyance direction (forward direction). [Figure 7] It is a diagram showing another example of a state of reading all patches over a plurality of columns and a plurality of rows of a color measurement chart image printed on continuous paper. [Figure 8] It is a diagram showing an example of a state in which a detection unit detects a trigger patch formed on continuous paper conveyed in the direction opposite to the conveyance direction. [Figure 9] It is a diagram showing an example of a state in which a first detection unit detects a first trigger patch formed on continuous paper conveyed in the conveyance direction (forward direction). [Figure 10] It is a diagram showing an example of a state in which a second detection unit detects a second trigger patch formed on continuous paper conveyed in the direction opposite to the conveyance direction. MODE FOR CARRYING OUT THE INVENTION

[0022] The embodiments of this disclosure will be described in detail below with reference to the drawings.

[0023] The image forming system 100 according to this embodiment is a system for forming an image on paper. As shown in Figure 1, the image forming system 100 comprises a paper feeder 10, an image forming apparatus 20, an image reading apparatus 30, and a winding apparatus 40. In this embodiment, a configuration using continuous paper PM such as roll paper or continuous forms will be described as an example.

[0024] The paper feeder 10 houses the continuous paper PM and feeds the continuous paper PM to the image forming apparatus 20. Inside the housing of the paper feeder 10, the roll-shaped continuous paper PM is wound around a support shaft and held in a rotatable manner.

[0025] The image forming apparatus 20 forms an image on continuous paper PM fed from the paper feeder 10. As shown in Figures 2 and 3, the image forming apparatus 20 includes a control unit 21, an image reading unit 22, an image forming unit 23, a transport unit 24, an operation panel 25, a storage unit 26, and a communication unit 27.

[0026] The control unit 21 is comprised of a CPU, RAM, ROM, etc. First, the CPU reads various processing programs stored in ROM and loads them into RAM in response to signals input from the operation unit 252 or the communication unit 27. Next, the CPU comprehensively controls the operation of the image forming apparatus 20 in cooperation with the various programs loaded into RAM.

[0027] First, the image reading unit 22 scans and exposes the image of the document placed on the document glass or automatic document feeder (ADF) using the optical system of the scanning exposure device. Next, the image reading unit 22 reads the reflected light during scanning exposure using a line image sensor to obtain an image signal. This image signal is processed with A / D conversion, shading correction, compression, etc., and then input to the control unit 21 as image data. Note that the image data input to the control unit 21 is not limited to what the image reading unit 22 has read. The image data input to the control unit 21 may, for example, be received from an external device (not shown) via the communication unit 27.

[0028] The image forming unit 23 forms an image consisting of four colors, C, M, Y, and K, on ​​continuous paper PM, according to the pixel values ​​of the four colors of each pixel of the image processed from the original image. The image forming unit 23 includes four writing units 231, an intermediate transfer belt 232, a secondary transfer roller 233, a fixing unit 234, and the like.

[0029] The four writing units 231 are arranged in series (tandem) along the belt surface of the intermediate transfer belt 232 and form images of C, M, Y, and K colors. Each writing unit 231 has the same configuration except for the color of the image it forms. Each writing unit 231 comprises an exposure unit 231a, a photoreceptor 231b, a developing unit 231c, a charging unit 231d, a cleaning unit 231e, and a primary transfer roller 231f.

[0030] Each writing unit 231 first charges the photoreceptor 231b with the charging unit 231d during image formation. Next, each writing unit 231 scans the photoreceptor 231b with a light beam emitted from the exposure unit 231a based on the image data (original image), forming an electrostatic latent image on the photoreceptor 231b. Next, each writing unit 231 supplies toner to the electrostatic latent image formed on the photoreceptor 231b using the developing unit 231c, and develops it. As a result, an image (monochromatic toner image) is formed on the photoreceptor 231b.

[0031] Next, each writing unit 231 sequentially transfers the images formed on the photoreceptor 231b onto the intermediate transfer belt 232 using its respective primary transfer roller 231f. As a result, an image consisting of each color (color toner image) is formed on the intermediate transfer belt 232. Next, each writing unit 231 removes any remaining toner from the photoreceptor 231b using its cleaning unit 231e.

[0032] The paper feeder 10 feeds continuous paper PM in accordance with the timing that the image on the rotating intermediate transfer belt 232 reaches the position of the secondary transfer roller 233. The secondary transfer roller 233 consists of a pair of rollers. One roller presses against the intermediate transfer belt 232. The other roller is one of several rollers that wind around the intermediate transfer belt 232. The secondary transfer roller 233 transfers the toner image that was primarily transferred to the outer surface of the intermediate transfer belt 232 to the continuous paper PM. Once the image is transferred to the continuous paper PM by the pressure of the secondary transfer roller 233, a fixing process is performed in the fixing unit 234 and the paper is sent to the image reading device 30. The fixing process is a process in which the continuous paper PM is heated and pressurized to fix the image to the continuous paper PM.

[0033] The transport unit 24 is a continuous paper PM transport mechanism having multiple rollers. First, the transport unit 24 transports the continuous paper PM fed from the paper feed device 10 to the image forming unit 23. Next, the transport unit 24 transports the continuous paper PM that has passed through the image forming unit 23 to the image reading device 30.

[0034] The control panel 25 includes a display unit 251 that displays various information to the user and an operation unit 252 that receives operation input from the user.

[0035] The display unit 251 is composed of a color liquid crystal display or the like. The display unit 251 displays operation screens, etc., according to display control signals input from the control unit 21. The operation screens include, for example, various setting screens, various buttons, and the operating status of each function.

[0036] The operation unit 252 includes a touch panel provided on the screen of the display unit 251 and various hard keys arranged around the screen of the display unit 251. When a button displayed on the screen is pressed with a finger or stylus, the operation unit 252 first detects the XY coordinates of the point of force application as a voltage value. Next, the operation unit 252 outputs an operation signal corresponding to the detected position to the control unit 21. The touch panel is not limited to pressure-sensitive; for example, it may be electrostatic or optical. Also, when a hard key is pressed, the operation unit 252 outputs an operation signal corresponding to the pressed key to the control unit 21. The user can operate the operation unit 252 to perform settings related to image formation, paper transport instructions, and stop operations of the device. Settings related to image formation include, for example, image quality settings, magnification settings, application settings, output settings, and paper settings.

[0037] The storage unit 26 is a non-volatile storage means composed of an HDD (Hard Disk Drive), SSD (Solid State Drive), etc. The storage unit 26 stores various programs and various setting data so that they can be read and written by the control unit 21.

[0038] The communication unit 27 has a communication IC and a communication connector, and is an interface that connects the image forming apparatus 2 to a communication network. Under the control of the control unit 21, the communication unit 27 transmits and receives various information with external devices connected to the communication network using a predetermined communication protocol. The communication unit 27 can also input and output various information via USB.

[0039] The image reading device 30 is connected downstream of the image forming apparatus 20 and optically reads the image formed on continuous paper PM by the image forming apparatus 20. As shown in Figures 1 and 3, the image reading device 30 comprises a control unit 31, an image reading unit 32, a colorimetric unit 33, a transport unit 34, and a detection unit 35.

[0040] The control unit 31 includes a CPU, ROM, RAM, etc., and comprehensively controls the operation of each part of the image reading device 30.

[0041] The image reading unit 32 scans both sides of the continuous paper PM on which an image has been formed by the image forming unit 23, and optically reads the images on both sides of the continuous paper PM. The read image obtained by the image reading unit 32 is output to the control unit 21 of the image forming apparatus 20 via the control unit 31.

[0042] The colorimeter 33 is positioned downstream of the image reading unit 32 in the transport direction of the continuous paper PM, and measures the color of the image formed on the continuous paper PM by the image forming unit 23. The colorimeter 33 spectrally measures the color of each color patch in the patch image formed on the continuous paper PM by the image forming unit 23 and acquires colorimetric data. The colorimetric results from the colorimeter 33 are output to the control unit 21 of the image forming apparatus 20 via the control unit 31. The colorimeter 33 is configured to be movable in the width direction (CD direction) perpendicular to the transport direction of the continuous paper PM.

[0043] The transport unit 34 is a transport mechanism for continuous paper PM having multiple rollers. The transport unit 34 transports the continuous paper PM transported from the image forming apparatus 20 to the winding device 40. This enables image reading by the image reading unit 32 and color measurement by the color measurement unit 33.

[0044] The detection unit 35 is an optical sensor that optically detects trigger patches formed on continuous paper PM. The trigger patch is a patch that indicates the timing to start color measurement by the colorimeter 33. The detection result (detection of the trigger patch) from the detection unit 35 is output to the control unit 31. When the control unit 31 receives the detection result from the detection unit 35, it generates a color measurement trigger signal. The control unit 31 then starts color measurement by the colorimeter 33 at a predetermined time after the generation of the color measurement trigger signal. The detection unit 35 is located further outward (downward in Figure 6) than the colorimeter unit 33 in the width direction of the continuous paper PM (see Figure 6). Furthermore, the detection unit 35 is located at approximately the same position as the colorimeter unit 33 in the transport direction of the continuous paper PM (see Figure 6).

[0045] The winding device 40 winds the continuous paper PM, which has been fed out by the image reading device 30, into a roll. Inside the housing of the winding device 40, the continuous paper PM is wound around a support shaft and held in a roll.

[0046] Next, the control of the image forming system 1 according to this embodiment will be explained with reference to the flowchart in Figure 4. The control in Figure 4 is the control of reading all patches across multiple columns and rows of the colorimetric chart image printed on continuous paper PM with the colorimetric unit 33. In the example shown in Figure 4, the control unit 21 of the image forming apparatus 20 is given a central role (a command center role) and instructs the control units of each device to execute processing, but this is not the only example. For example, the control unit 31 of the image reading device 30 (or a control unit provided separately from each device (not shown)) may be given a central role. Alternatively, the control units 21 and 31 of each device constituting the image forming system 100 (image forming apparatus 20, image reading device 30) may cooperate to execute processing.

[0047] First, the control unit 21 causes the image forming unit 23 to form a colorimetric chart image on the continuous paper PM (step S101).

[0048] Next, the control unit 21 transports the continuous paper PM on which the colorimetric chart image is formed to the color measurement position (step S102). Specifically, the control unit 21 transports the continuous paper PM so that the colorimetric chart image formed on the continuous paper PM reaches the color measurement position by the color measurement unit 33. The transport of the continuous paper PM is carried out by the cooperation of the paper feeder 10, transport unit 24, transport unit 34, and winding device 40.

[0049] Next, the control unit 21 causes the colorimetric chart image formed on the continuous paper PM by the colorimetric unit 33 to be measured, while the continuous paper PM is transported in the transport direction for the length of the colorimetric chart image (step S103). In this embodiment, the colorimetric unit 33 measures the image only when the continuous paper PM is being transported in the transport direction.

[0050] Next, the control unit 21 determines whether or not the entire colorimetric chart image has been read by the colorimetric unit 33 (step S104). The control unit 21 terminates the process when it determines that the colorimetric unit 33 has read all of the colorimetric chart images (step S104: YES). On the other hand, if the control unit 21 determines that the colorimetric chart image has not been fully read by the colorimetric unit 33 (step S104: NO), it proceeds to the next step S105.

[0051] In step S105, the control unit 21 moves the colorimeter 33 a predetermined distance in the width direction (CD direction) perpendicular to the transport direction of the continuous paper PM. The predetermined distance is a distance (one line) corresponding to the size of the colorimeter patch formed on the continuous paper PM.

[0052] Next, the control unit 21 causes the continuous paper PM to be rewound and transported in the reverse direction of the transport direction by the length of the colorimetric chart image (step S106).

[0053] Next, the control unit 21 transports the continuous paper PM until the transport speed stabilizes (step S107). Specifically, the control unit 21 transports the continuous paper PM until the transport speed reaches a predetermined speed. Here, the predetermined speed is a speed at which it is considered possible to perform color measurement appropriately. After that, the process proceeds to step S103 and is repeated until the color measurement of all lines is completed. In other words, the colorimeter 33 starts measuring the color of the image after the transport speed of the continuous paper PM by the transport unit reaches a predetermined speed.

[0054] This allows all patches across multiple columns and rows of the colorimetric chart image printed on continuous paper PM to be read. Note that steps S105 and S106 can be performed in any order; the process can be performed in the order of step S106 → step S105.

[0055] As described above, the control unit 21 controls a first operation in which the transport unit (transport unit 34, etc.) transports the continuous paper PM in the transport direction for a predetermined length and then rewinds and transports it in the reverse direction for a predetermined length. The predetermined length is the length of the colorimetric chart image. Furthermore, the control unit 21 controls a second operation to move the colorimeter 33 a predetermined distance in the width direction (CD direction) perpendicular to the transport direction of the continuous paper PM. The predetermined distance is a distance (one line) corresponding to the size of the colorimeter patch formed on the continuous paper PM. The control unit 21 then repeats the first and second operations until the color measurement of the image by the colorimeter 33 is completed.

[0056] Figure 5 shows an example of reading all patches across multiple columns and rows of a colorimetric chart image CG printed on continuous paper PM.

[0057] First, the colorimeter 33 is moved to the CD direction (width direction of the continuous paper PM) end of the colorimeter chart image CG (Procedure 1). This minimizes the movement distance of the colorimeter 33. In Procedure 1 of Figure 5, the colorimeter 33 is positioned at the front end (bottom end in the figure), but it may also be positioned at the back end (top end in the figure). In other words, the initial position of the colorimetric unit 33 is at either end of the width direction of the colorimetric chart image CG formed on the continuous paper PM.

[0058] Next, while the continuous paper PM is transported in the transport direction (forward direction), the colorimeter 33 performs color measurement on one line (step 2).

[0059] Next, the colorimeter 33 is moved one patch (one row) in the CD direction (step 3).

[0060] Next, the continuous paper PM is transported in the reverse direction of the transport direction (rewind transport) (Step 4).

[0061] Next, the continuous paper PM is transported in the transport direction (forward direction), and the transport of the continuous paper PM is continued until the speed stabilizes. Then, the process moves to step 2 and is repeated until the color measurement of all rows is completed. This allows all patches spanning multiple columns and rows of the color measurement chart image CG printed on the continuous paper PM to be read. Note that steps 3 and 4 are not in any order; the processing can be performed in the order of step 4 → step 3.

[0062] The timing at which the colorimeter 33 begins color measurement (the timing at which it reaches the color measurement position) is a predetermined time after the trigger patch formed on the continuous paper PM is detected by the detection unit 35. In other words, the colorimeter 33 begins measuring the color of the image after a predetermined time has elapsed since the trigger patch formed on the continuous paper PM was detected by the detection unit 35.

[0063] Figure 6 shows an example of how the detection unit 35 detects a trigger patch TP formed on continuous paper PM being transported in the transport direction (forward direction). As shown in Figure 6, trigger patches TP are provided in a one-to-one correspondence with each colorimetric patch SP. The trigger patches TP are located outside the width direction of the continuous paper PM (below in Figure 6) compared to the colorimetric patches SP. Furthermore, each trigger patch TP is located downstream in the transport direction from the reading position F of the corresponding colorimetric patch SP. In the example shown in Figure 6, the detection unit 35 is located at approximately the same position as the colorimetric unit 33 in the transport direction of the continuous paper PM, but this is not the only configuration. For example, the detection unit 35 may be located upstream of the colorimetric unit 33 in the transport direction of the continuous paper PM. In other words, it is sufficient that the detection of the trigger patch TP by the detection unit 35 occurs before the colorimetric patch SP is measured by the colorimetric unit 33.

[0064] As described above, the image forming system 100 according to this embodiment includes a control unit 21 that controls the first and second operations. The first operation involves the transport unit (transport unit 34, etc.) transporting the continuous paper PM by a predetermined length in the transport direction and then rewinding and transporting it by a predetermined length in the opposite direction to the transport direction. The second operation involves moving the colorimetric unit 33 a predetermined distance in the width direction perpendicular to the transport direction of the continuous paper PM. The control unit 21 repeats the first and second operations until the colorimetric unit 33 completes measuring the image. Therefore, even with a continuous-paper printing press, the chart image can be measured across the entire surface with a single colorimeter without lengthening the image or stopping at each patch interval. Thus, it is inexpensive, produces less waste, and allows for high-precision color measurement across the entire surface.

[0065] Furthermore, the colorimeter 33 measures the image only when the continuous paper PM is being transported in the transport direction. Therefore, the entire surface can be color-measured using existing transport control. Thus, the entire surface of continuous PM paper can be color-measured with high accuracy at low cost.

[0066] Furthermore, the predetermined distance is a distance corresponding to the size of the colorimetric patch formed on the continuous paper PM. Therefore, multiple rows of colorimetric patches formed on continuous PM paper can be measured with a single colorimeter. This results in less wear and tear, lower costs, and high-precision color measurement across the entire surface of the continuous PM paper.

[0067] Furthermore, the colorimeter 33 starts measuring the color of the image after the transport speed of the continuous paper PM by the transport unit reaches a predetermined speed. Therefore, the transport speed during color measurement by the colorimeter 33 can be stabilized. Thus, the color measurement accuracy of continuous paper PM can be ensured.

[0068] Furthermore, the initial position of the colorimetric unit 33 is at either end of the widthwise direction of the colorimetric chart image formed on the continuous paper PM. Therefore, the travel distance of the colorimeter 33 can be minimized. As a result, color measurement by the colorimeter 33 can be performed more efficiently, improving productivity.

[0069] The system also includes a detection unit 35 that detects a trigger patch indicating the timing for starting color measurement by the colorimeter 33. The colorimeter 33 starts measuring the color of an image after a predetermined time has elapsed since the trigger patch formed on the continuous paper PM was detected by the detection unit 35. Therefore, the timing for starting color measurement can be accurately determined. Thus, sufficient color measurement accuracy for continuous paper PM can be ensured.

[0070] Although the embodiments described above have been specifically explained based on the embodiments of this disclosure, this disclosure is not limited to the embodiments described above and may be modified without departing from its essence.

[0071] For example, the above embodiment illustrates a configuration in which color measurement is performed only when the continuous paper PM is transported in the forward direction, but it is not limited to this. That is, a configuration in which color measurement is performed not only when transporting in the forward direction but also when transporting in the reverse direction is also possible.

[0072] Figure 7 shows another example of reading all patches across multiple columns and rows of a colorimetric chart image CG printed on continuous paper PM.

[0073] First, the colorimeter 33 is moved to the CD-direction end of the colorimeter chart image CG (Procedure 1). This minimizes the distance the colorimeter 33 needs to travel. In Procedure 1 of Figure 7, the colorimeter 33 is positioned at the front end (bottom end in the figure), but it may also be positioned at the back end (top end in the figure).

[0074] Next, while the continuous paper PM is transported in the transport direction (forward direction), the colorimeter 33 performs color measurement on one line (step 2).

[0075] Next, the colorimeter 33 is moved one patch (one row) in the CD direction (step 3).

[0076] Next, the continuous paper PM is transported in the reverse direction of the transport direction, and the transport of the continuous paper PM continues until the speed stabilizes. Then, while the continuous paper PM is transported in the reverse direction of the transport direction (rewind transport), the colorimeter 33 performs color measurement on one line (step 4).

[0077] Next, the colorimeter 33 is moved one patch (one row) in the CD direction (step 5). Then, the transport of the continuous paper PM in the transport direction (forward direction) is started and the transport of the continuous paper PM is continued until the speed stabilizes. After that, the process moves to step 2 and is repeated until the colorimeter of all rows is measured. This makes it possible to read all patches across multiple columns and rows of the colorimeter chart image CG printed on the continuous paper PM.

[0078] As described above, the colorimeter 33 measures the color of the image both when the continuous paper PM is being transported in the transport direction and when it is being transported in the opposite direction of the transport direction. Therefore, by effectively utilizing bidirectional transport, color measurement can be efficiently performed by the color measurement unit 33. Thus, productivity related to color measurement can be improved.

[0079] Furthermore, the colorimeter 33 may change a predetermined time (the time from trigger patch detection to the start of color measurement) depending on whether the continuous paper PM is being transported in the transport direction or in the opposite direction.

[0080] Figure 8 shows an example of how the detection unit 35 detects a trigger patch TP formed on continuous paper PM being transported in the opposite direction to the transport direction. The distance D1 between the trigger patch TP and the reading position F during forward transport (see Figure 6) is shorter than the distance D2 between the trigger patch TP and the reading position F during reverse transport (see Figure 8). In other words, the predetermined time during forward transport is shorter than the predetermined time during reverse transport. Note that distances D1 and D2 do not necessarily have to be different; they may be the same distance.

[0081] As described above, the colorimeter 33 changes the predetermined time depending on whether the continuous paper PM is being transported in the transport direction or in the opposite direction of the transport direction. Therefore, regardless of the transport direction, a single detection unit 35 can accurately detect the timing of the start of color measurement by the color measurement unit 33. Thus, sufficient color measurement accuracy for continuous paper PM can be ensured.

[0082] Furthermore, although the above embodiment illustrates a configuration in which a trigger patch TP is detected by a single detection unit 35, the invention is not limited to this configuration. For example, the detection unit of this disclosure may include a first detection unit 35A and a second detection unit 35B. In this case, the first detection unit 35A detects a first trigger patch TP1 that indicates the timing to start color measurement by the color measurement unit 33 when the continuous paper PM is being transported in the transport direction. The second detection unit 35B detects a second trigger patch TP2 that indicates the timing to start color measurement by the color measurement unit 33 when the continuous paper PM is being transported in the opposite direction to the transport direction.

[0083] Figure 9 shows an example of how the first detection unit 35A detects the first trigger patch TP1 formed on the continuous paper PM being transported in the transport direction (forward direction). As shown in Figure 9, the first trigger patch TP1 is provided in a one-to-one correspondence with each colorimetric patch SP. The first trigger patch TP1 is located outside the width direction of the continuous paper PM (below in Figures 9 and 10) compared to the colorimetric patch SP. Furthermore, each first trigger patch TP1 is located downstream in the transport direction from the reading position F of the corresponding colorimetric patch SP. This allows the first trigger patch TP1 to be detected before the colorimetric patch SP is read during forward transport.

[0084] Figure 10 shows an example of how the second detection unit 35B detects a second trigger patch TP2 formed on continuous paper PM being transported in the opposite direction to the transport direction. As shown in Figure 10, the second trigger patch TP2 is provided in a one-to-one correspondence with each colorimetric patch SP. The second trigger patch TP2 is located on the outside in the width direction of the continuous paper PM (upwards in Figures 9 and 10) compared to the colorimetric patch SP. Furthermore, each second trigger patch TP2 is located upstream in the transport direction (downstream in the transport direction during reverse transport) compared to the reading position F of the corresponding colorimetric patch SP. This allows the second trigger patch TP2 to be detected before the colorimetric patch SP is read during reverse transport.

[0085] As described above, the detection unit 35 comprises a first detection unit 35A and a second detection unit 35B. The first detection unit 35A detects a first trigger patch TP1 that indicates the timing to start color measurement by the color measurement unit 33 when the continuous paper PM is being transported in the transport direction. The second detection unit 35B detects a second trigger patch TP2 that indicates the timing to start color measurement by the color measurement unit 33 when the continuous paper PM is being transported in the opposite direction of the transport direction. Therefore, regardless of the transport direction, the timing of the start of color measurement by the color measurement unit 33 can be accurately detected. Thus, sufficient color measurement accuracy for continuous paper PM can be ensured.

[0086] Furthermore, while the above embodiment illustrates a configuration in which the entire image forming system 1 (paper feeder 10, transport unit 24, transport unit 34, and winding device 40) transports continuous paper PM, it is not limited to this configuration. For example, a paper buffer may be provided between the image forming device 20 and the image reading device 30, or between the image reading device 30 and the winding device 40, and only the transport unit 34 of the image reading device 30 may be controlled to transport the continuous paper PM. The paper buffer may be, for example, a path that allows for slack in the paper length corresponding to the colorimetric chart image.

[0087] Furthermore, in the above embodiment, the color measurement of the image is started after the transport speed of the continuous paper PM by the transport unit (transport unit 34, etc.) reaches a predetermined speed, but the invention is not limited to this. For example, the color measurement of the image may be started after the continuous paper PM has been transported by the transport unit for a predetermined distance or time. Here, the predetermined distance or time is a distance or time at which it can be considered that the transport speed is stable and color measurement can be performed appropriately.

[0088] As described above, the colorimeter 33 starts measuring the color of the image after the continuous paper PM has been transported by the transport unit over a predetermined distance or time. Therefore, the transport speed during color measurement by the colorimeter 33 can be stabilized. Thus, the color measurement accuracy of continuous paper PM can be ensured.

[0089] Furthermore, the detailed configuration and detailed operation of each device constituting the image forming system may also be modified as appropriate, without departing from the spirit of this disclosure. [Explanation of symbols]

[0090] 100 Image Forming Systems 10 Paper feeder 20 Image forming apparatus 21 Control Unit 22 Image reading unit 23 Image forming unit 231 Writing section 231a Exposure area 231b Photoreceptor 231c Developing section 231d Charged part 231e Cleaning Department 231f Primary Transfer Roller 232 Intermediate transfer belt 233 Secondary Transfer Roller 234 Fixing section 24 Conveying section 25 Control Panel 251 Display section 252 Operation section 26 Memory section 27 Communications Department 30 Image reading device 31 Control Unit 32 Image reading unit 33 Color measurement section 34 Conveying section 35 Detection unit 40 Winding device PM continuous paper

Claims

1. An image forming system comprising: an image forming unit for forming an image on continuous paper; a colorimetric unit for measuring the color of the image formed on the continuous paper by the image forming unit; and a transport unit for transporting the continuous paper, The control unit controls a first operation in which the transport unit transports the continuous paper by a predetermined length in the transport direction and rewinds and transports it by the predetermined length in the opposite direction of the transport direction, and a second operation in which the colorimeter moves the colorimeter by a predetermined distance in the width direction perpendicular to the transport direction of the continuous paper. The control unit repeats the first operation and the second operation until the color measurement of the image by the colorimeter is completed, characterized in that the image forming system.

2. The image forming system according to claim 1, characterized in that the colorimeter measures the image only when the continuous paper is being transported in the transport direction.

3. The image forming system according to claim 1, characterized in that the colorimeter measures the image both when the continuous paper is being transported in the transport direction and when it is being transported in the opposite direction to the transport direction.

4. The image forming system according to claim 1, characterized in that the predetermined distance is a distance corresponding to the size of the colorimetric patch formed on the continuous paper.

5. The image forming system according to claim 1, characterized in that the colorimetric unit starts measuring the color of the image after the transport speed of the continuous paper by the transport unit reaches a predetermined speed.

6. The image forming system according to claim 1, characterized in that the colorimetric unit starts measuring the color of the image after the continuous paper has been transported by the transport unit for a predetermined distance or time.

7. The image forming system according to claim 1, characterized in that the initial position of the colorimetric unit is at either of the ends in the width direction of the colorimetric chart image formed on the continuous paper.

8. The system includes a detection unit that detects a trigger patch indicating the timing for starting color measurement by the color measurement unit, The image forming system according to claim 1, characterized in that the colorimeter starts measuring the color of the image after a predetermined time has elapsed since the trigger patch formed on the continuous paper was detected by the detection unit.

9. The detection unit, A first detection unit detects a first trigger patch that indicates the timing for starting color measurement by the color measurement unit when the continuous paper is being transported in the transport direction, A second detection unit detects a second trigger patch that indicates the timing to start color measurement by the color measurement unit when the continuous paper is being transported in the opposite direction to the transport direction, The image forming system according to claim 8, characterized by comprising:

10. The image forming system according to claim 8, characterized in that the colorimetric unit changes the predetermined time depending on whether the continuous paper is being transported in the transport direction or in the opposite direction to the transport direction.

11. A color measurement control method for an image forming system comprising: an image forming unit for forming an image on continuous paper; a color measurement unit for measuring the color of the image formed on the continuous paper by the image forming unit; and a transport unit for transporting the continuous paper, wherein The control process includes a first operation in which the transport unit transports the continuous paper by a predetermined length in the transport direction and rewinds and transports it by the predetermined length in the opposite direction of the transport direction, and a second operation in which the colorimeter moves a predetermined distance in the width direction perpendicular to the transport direction of the continuous paper. The control step is characterized by repeating the first operation and the second operation until the color measurement of the image by the colorimeter is completed.

12. A computer for an image forming system comprising: an image forming unit that forms an image on continuous paper; a colorimetric unit that measures the color of the image formed on the continuous paper by the image forming unit; and a transport unit that transports the continuous paper. The control unit functions as a control unit that controls a first operation in which the transport unit transports the continuous paper by a predetermined length in the transport direction and rewinds and transports it by the predetermined length in the opposite direction of the transport direction, and a second operation in which the colorimeter unit moves a predetermined distance in the width direction perpendicular to the transport direction of the continuous paper. The control unit is characterized by repeating the first operation and the second operation until the color measurement of the image by the colorimeter is completed.

Images