Image forming system, conveyance speed control method, and program

Abstract

To provide an image forming system, a conveyance speed control method, and a program that can create a high-quality print without imposing restrictions on a reference image formation position and without increasing cost.SOLUTION: An image forming system comprises: an image forming unit 33 that forms an image on a sheet; reading units (image reading unit 42, colorimeter 43) that read the image on the sheet formed by the image forming unit 33; a media sensor 23 that detects a physical property value of the sheet; and a control unit 31 that controls a conveyance speed of the sheet in the reading units according to the physical property value detected by the media sensor 23.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an image forming system, a conveyance speed control method, and a program.

Background Art

[0002] Conventionally, an image forming apparatus that forms an image on a sheet is known. Sheets used by the image forming apparatus are of various types (characteristics). In order to produce high-quality printed matter, it is necessary to adjust the image position on the sheet. Therefore, for example, a configuration is known in which a reference image formed on a sheet is read by a reading unit and the result is fed back to the image forming unit. According to this configuration, the image positions on the front and back of the sheet can be aligned.

[0003] By the way, when the reading unit reads the reference image used for front-back position adjustment, high-precision position detection is required. However, in the conventional configuration, it is widely known that shock noise occurs when reading the reference image used for front-back position adjustment. Shock noise occurs when the sheet enters the conveyance roller or conveyance roller near the reading unit. When height fluctuations or speed fluctuations of the sheet occur due to shock noise during sheet conveyance to the reading unit, adverse effects such as pitch unevenness and magnification fluctuations occur in the read image. That is, the occurrence of shock noise affects the accuracy of position detection by the reading unit.

[0004] Therefore, Patent Document 1 discloses a configuration in which a reference image is formed at a position shifted from the position read by the reading unit when shock noise occurs. Also, Patent Document 2 discloses a configuration in which the distance between the reading position of the reading unit and the conveyance roller can be adjusted.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0006] However, in the configuration described in Patent Document 1, there is a problem that the movable image is limited, so the usage is limited. Further, in the configuration described in Patent Document 2, since a mechanism for moving the conveyance roller is required, there is a problem that the cost increases. Also, in any configuration, depending on the paper type, shock noise may increase during reading by the reading unit. In particular, when thick paper or paper with high stiffness enters the conveyance roller or conveyance roller near the reading unit, the shock noise may increase. Therefore, simply adjusting the reading timing of the reference image or the position of the conveyance roller may not be able to reduce the influence of the shock noise.

[0007] An object of the present invention is to provide an image forming system, a conveyance speed control method, and a program capable of generating a high-quality printed matter without providing a limitation on the formation position of a reference image and without increasing the cost.

MEANS FOR SOLVING THE PROBLEMS

[0008] The invention according to claim 1 has been made to achieve the above object, in an image forming system, an image forming unit that forms an image on a sheet; a reading unit that reads the image formed on the sheet by the image forming unit; a control unit that controls the conveyance speed of the sheet in the reading unit according to the physical property value of the sheet; and is characterized by comprising:

[0009] The invention according to claim 2 is the image forming system according to claim 1, comprising a media sensor that detects the physical property value, The control unit controls the conveyance speed according to the physical property value detected by the media sensor.

[0010] The invention according to claim 3 is an image forming system according to claim 2, wherein The media sensor includes at least one of a stiffness sensor that detects the stiffness of the paper, a paper thickness sensor that detects the paper thickness of the paper, a moisture content sensor that detects the moisture content of the paper, and a basis weight sensor that detects the basis weight of the paper.

[0011] The invention according to claim 4 is an image forming system according to claim 2, wherein The media sensor is disposed upstream of the image forming unit in the paper conveyance direction.

[0012] The invention according to claim 5 is an image forming system according to claim 2, wherein The media sensor is disposed downstream of the image forming unit in the paper conveyance direction and upstream of the reading unit in the paper conveyance direction.

[0013] The invention according to claim 6 is an image forming system according to claim 1, wherein An adjustment unit is provided that adjusts the image forming position of the paper according to the reading result obtained by reading a reference image for position adjustment formed on the paper by the reading unit.

[0014] The invention according to claim 7 is an image forming system according to claim 6, wherein The adjustment unit adjusts the image forming positions on the front and back of the paper.

[0015] The invention according to claim 8 is an image forming system according to claim 1, wherein The control unit controls the conveyance speed when the reading unit reads a reference image for image adjustment formed on the paper.

[0016] The invention according to claim 9 is the image forming system according to claim 1, wherein an acquisition unit that acquires the physical property value based on the paper information set by the user via the setting unit is provided, the control unit controls the conveyance speed according to the physical property value acquired by the acquisition unit.

[0017] The invention according to claim 10 is the image forming system according to claim 3, wherein the control unit slows down the conveyance speed as the stiffness detected by the stiffness sensor is higher.

[0018] The invention according to claim 11 is the image forming system according to claim 3, wherein the control unit slows down the conveyance speed as the paper thickness detected by the paper thickness sensor is thicker.

[0019] The invention according to claim 12 is the image forming system according to claim 3, wherein the control unit slows down the conveyance speed as the moisture content detected by the moisture content sensor is lower.

[0020] The invention according to claim 13 is the image forming system according to claim 3, wherein the control unit slows down the conveyance speed as the basis weight detected by the basis weight sensor is larger.

[0021] The invention according to claim 14 is the image forming system according to claim 2, wherein the media sensor includes a stiffness sensor that detects the stiffness of the paper, the control unit causes the stiffness sensor to detect the stiffness before executing the print job.

[0022] The invention according to claim 15 is the image forming system according to claim 2, wherein The media sensor includes a paper thickness sensor that detects the paper thickness of the paper, a moisture content sensor that detects the moisture content of the paper, and a basis weight sensor that detects the basis weight of the paper. The control unit is characterized by controlling the conveyance speed during the execution of a printing job according to at least any one of the paper thickness detected by the paper thickness sensor, the moisture content detected by the moisture content sensor, and the basis weight detected by the basis weight sensor.

[0023] The invention according to claim 16 is an image forming system according to claim 1, The control unit is characterized by controlling the conveyance speed until a reference image for image adjustment formed on the paper enters the reading unit.

[0024] The invention according to claim 17 is an image forming system according to claim 1, The control unit is characterized by controlling the conveyance speed until the leading edge of the paper enters the reading unit.

[0025] The invention according to claim 18 is A method for controlling the conveyance speed of an image forming system including an image forming unit that forms an image on a paper and a reading unit that reads the image formed on the paper by the image forming unit, characterized by including a control step of controlling the conveyance speed of the paper in the reading unit according to the physical property value of the paper.

[0026] The invention according to claim 19 is A program for causing a computer of an image forming system including an image forming unit that forms an image on a paper and a reading unit that reads the image formed on the paper by the image forming unit to function as a control unit that controls the conveyance speed of the paper in the reading unit according to the physical property value of the paper.

Advantages of the Invention

[0027] According to the present invention, high-quality printed matter can be generated without imposing restrictions on the formation position of the reference image and without increasing costs.

Brief Description of the Drawings

[0028]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0029] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0030] As shown in FIGS. 1 and 2, an image forming system 1 according to the present embodiment includes a paper feeding device 10, a paper information detecting device 20, an image forming device 30, and an image reading device 40. The image forming system 1 is connected in the order of the paper feeding device 10, the paper information detecting device 20, the image forming device 30, and the image reading device 40 along the conveyance direction of the paper P.

[0031] The paper feeding device 10 includes a plurality of paper feeding trays 11 and paper feeding means (not shown), and feeds the paper P stored in the paper feeding tray 11 to the paper information detection device 20. The paper feeding means is composed of, for example, a paper feeding roller, a separating roller, a paper feeding / separating rubber, a feeding roller, etc. Each paper feeding tray 11 stores the paper P according to the type of the paper P (paper type, basis weight, paper size, etc.). The paper feeding device 10 conveys the paper P one by one from the top of the paper P stored in each paper feeding tray 11 to the paper information detection device 20.

[0032] The paper information detection device 20 is connected to the subsequent stage of the paper feeding device 10. The paper information detection device 20 includes a control unit 21, a conveying unit 22, and a media sensor 23.

[0033] The control unit 21 includes a CPU, a ROM, a RAM, etc., and comprehensively controls the operations of each part of the paper information detection device 20.

[0034] The conveying unit 22 is composed of a plurality of roller pairs. The conveying unit 22 conveys the paper P conveyed from the paper feeding device 10 to the image forming device 30 or the purge tray T20. The conveying unit 22 includes a stiffness detection path R22 that branches from the conveying path R21 leading to the image forming device 30 and leads to the purge tray T20.

[0035] The media sensor 23 detects the physical property values of the paper P. The media sensor 23 includes a paper thickness sensor 231, a moisture content sensor 232, a basis weight sensor 233, and a stiffness sensor 234. The paper thickness sensor 231 detects the paper thickness of the paper P. The moisture content sensor 232 detects the moisture content of the paper P. The basis weight sensor 233 detects the basis weight of the paper P. The stiffness sensor 234 detects the stiffness of the paper P. The paper thickness sensor 231, the moisture content sensor 232, and the basis weight sensor 233 are arranged on the conveying path R21 leading to the image forming device 30. The stiffness sensor 224 is located on the stiffness detection path R22 that leads to the purge tray T20, near the branch portion from the conveyance path R21. The stiffness sensor 224 detects the stiffness of the sheet P by reading the force applied to the sheet P bent at the branch portion. The sheet P whose stiffness is detected by the stiffness sensor 224 is discharged to the purge tray T20.

[0036] In the present embodiment, as shown in FIG. 1, the media sensor 23 is arranged on the upstream side of the conveyance direction of the sheet P from the image forming unit 33.

[0037] The image forming apparatus 30 is connected to the subsequent stage of the sheet information detection apparatus 20. The image forming apparatus 30 includes a control unit 31, a storage unit 32, an image forming unit 33, an operation display unit 34, a conveyance unit 35, and a communication unit 36. The image forming apparatus 30 forms an image on the sheet P conveyed from the sheet information detection apparatus 20.

[0038] The control unit 31 has a CPU and a memory, and controls the entire image forming apparatus 30. The CPU is a control circuit composed of a multi-core processor or the like that executes the control of each unit and various arithmetic processes according to a program. Each function of the image forming apparatus 30 is exhibited by the CPU executing a corresponding program. The memory is a high-speed accessible main storage device that temporarily stores programs and data as a work area. For example, DRAM, SDRAM, SRAM, etc. are adopted for the memory.

[0039] For example, the control unit 31 controls the conveyance speed of the sheet P in the reading unit according to the physical property values (stiffness, paper thickness, moisture content, basis weight) of the sheet P. Specifically, the control unit 31 controls the conveyance speed according to the physical property values detected by the media sensor 23.

[0040] The storage unit 32 is a large-capacity auxiliary storage device that stores various programs including an operating system and various data. For the storage, for example, a hard disk, a solid state drive, a flash memory, a ROM, etc. are adopted. The storage unit 32 stores, for example, the stiffness of the sheet P detected by the stiffness sensor 224. Further, the storage unit 32 stores a paper conveyance speed table TA1. The paper conveyance speed table TA1 is a table showing the correspondence between the physical property values of the sheet P and the conveyance speed of the sheet P in the reading unit.

[0041] Fig. 3 shows an example of the paper conveyance speed table TA1. The control unit 31 collates the physical property values (stiffness, paper thickness, moisture content, basis weight) of the sheet P with the paper conveyance speed table TA1 to determine the target value of the conveyance speed. In the example shown in Fig. 3, it is assumed that the normal (default) conveyance speed (normal linear speed) is "1000 mm / s". For example, when the stiffness is "500", the paper thickness is "140 μm", the moisture content is "7%", and the basis weight is "90 g / m 2 ", the target value of the conveyance speed is determined to be "1000 mm / s". Also, when the stiffness is "500", the paper thickness is "400 μm", the moisture content is "5%", and the basis weight is "350 g / m 2 ", the target value of the conveyance speed is determined to be "800 mm / s". Also, when the stiffness is "1000", the paper thickness is "400 μm", the moisture content is "3%", and the basis weight is "400 g / m 2 ", the target value of the conveyance speed is determined to be "500 mm / s". As shown in Fig. 3, the higher the stiffness, the slower the target value of the conveyance speed. Also, the thicker the paper thickness, the slower the target value of the conveyance speed. Also, the lower the moisture content, the slower the target value of the conveyance speed. Also, the larger the basis weight, the slower the target value of the conveyance speed. The control unit 31 slows down the conveyance speed as the stiffness detected by the stiffness sensor 224 is higher. Also, the control unit 31 slows down the conveyance speed as the paper thickness detected by the paper thickness sensor 231 is thicker. Also, the control unit 31 slows down the conveyance speed as the moisture content detected by the moisture content sensor 232 is lower. Also, the control unit 31 slows down the conveyance speed as the basis weight detected by the basis weight sensor 233 is larger.

[0042] The image forming unit 33 forms an image on the sheet P conveyed from the sheet information detection device 20 or the sheet P fed and conveyed from the paper feed tray T30 of the device itself. The image forming unit 33 forms an image on the sheet P using, for example, a well-known image forming process of the electrophotographic method including the steps of charging, exposure, development, transfer, and fixing.

[0043] The operation display unit 34 includes a touch panel, numeric keypad, start button, stop button, etc., and is used for displaying various information and inputting various instructions. The user can set the sheet information of the sheet P stored in each paper feed tray T30 via the operation display unit 34. That is, the operation display unit 34 functions as the setting unit of the present invention for setting the sheet information of the sheet P fed by the paper feeding device 10. Note that the sheet information includes, in addition to the paper type of the sheet P, the basis weight, size, etc. of the sheet P.

[0044] The conveyance unit 35 includes a plurality of conveyance rollers arranged on the conveyance path. First, the conveyance unit 35 conveys the sheet P conveyed from the sheet information detection device 20 or the sheet P fed from the paper feed tray T30 to the image forming unit 33. Next, the conveyance unit 35 discharges the sheet P on which an image has been formed by the image forming unit 33 to the image reading device 40.

[0045] The communication unit 36 performs transmission and reception of various setting values and various information necessary for operation timing control with other devices.

[0046] The image reading device 40 is connected to the subsequent stage of the image forming device 30 and includes a control unit 41, an image reading unit 42, a colorimeter 43, and a sheet detection sensor SE1.

[0047] The control unit 41 includes a CPU, ROM, RAM, etc., and comprehensively controls the operations of each part of the image reading device 40.

[0048] The image reading unit 42 scans both sides of the sheet P on which an image is formed by the image forming unit 33 and optically reads the images on both sides of the sheet P. That is, the image reading unit 42 functions as the reading unit of the present invention. The read image obtained by being read by the image reading unit 42 is output to the control unit 31 of the image forming apparatus 30. The sheet P read by the image reading unit 42 is discharged to the paper discharge tray T40. The control unit 31 adjusts the image forming position of the sheet P according to the reading result obtained by the image reading unit 42 reading the reference image G1 for position adjustment formed on the sheet P. That is, the control unit 31 functions as the adjustment unit of the present invention. FIG. 4 shows an example of the reference image G1 for position adjustment formed on the sheet P.

[0049] The image reading unit 42 includes a back surface image reading unit 42a and a front surface image reading unit 42b. The back surface image reading unit 42a is provided below the conveyance path R40 and reads the image formed on the back surface of the sheet P. The front surface image reading unit 42b is provided above the conveyance path R40 and reads the image formed on the front surface of the sheet P. The front surface image reading unit 42b is provided on the downstream side in the conveyance direction of the sheet P from the back surface image reading unit 42a. The back surface image reading unit 42a and the front surface image reading unit 42b are arranged at different positions with a distance therebetween in the conveyance direction of the sheet P. Thereby, both sides of the sheet P can be read in one pass. Therefore, the control unit 31 can adjust the image forming positions on the front and back of the sheet P.

[0050] FIG. 5 shows an example of the configuration of the image reading unit 42. In FIG. 5, the configuration of the back surface image reading unit 42a will be illustrated and described. Since the front surface image reading unit 42b has substantially the same configuration as the back surface image reading unit 42a, the description thereof will be omitted.

[0051] The back surface image reading unit 42a includes a CCD 421, an optical system 422, and an LED light source 423. The CCD (Charge Coupled Device) 421 is an optical sensor that reads an image formed on the sheet P at a predetermined reading position L. The CCD 421 is a color line sensor capable of reading the entire width range in the width direction of the sheet P. The optical system 422 includes a plurality of mirrors and a plurality of lenses, and guides the image at the reading position L to the CCD 421. The LED (Light Emitting Diode) light source 423 is a light source that illuminates the reading position L.

[0052] By having the above configuration, the backside image reading unit 42a can sequentially read an image formed on the sheet P over the entire width of the sheet P passing through the reading position L. When an image is read by the backside image reading unit 42a, the sheet P is conveyed by a plurality of conveying rollers 44 provided on the conveying path R40 so that the sheet P passes through the reading position L at a predetermined speed.

[0053] Above the backside image reading unit 42a, a calibration unit 424 is provided so as to sandwich the conveying path R40. The calibration unit 424 includes a white reference plate for determining a correction value for shading correction performed during image reading. The white reference plate is provided at the reading position L and is read by the CCD 421 at an interval when the sheet P does not pass (for example, between sheets P).

[0054] On the upper surface (the surface on the conveying path R40 side) of the backside image reading unit 42a, a first conveying guide roller 45 is provided. The first conveying guide rollers 45 are respectively inserted into a rotation axis orthogonal to the conveying direction of the sheet P and are rotatable about the rotation axis.

[0055] On the lower surface (the surface on the conveying path R40 side) of the calibration unit 424, a second conveying guide roller 46 is provided. The second conveying guide rollers 46 are respectively inserted into a rotation axis orthogonal to the conveying direction of the sheet P and are rotatable about the rotation axis.

[0056] The colorimeter 43 is disposed on the downstream side in the conveyance direction of the sheet P from the surface image reading unit 42b. The colorimeter 43 spectrally measures the color of each color patch of the patch image formed on the sheet P by the image forming unit 33 and acquires colorimetric data. That is, the colorimeter 43 functions as a reading unit of the present invention that reads the image formed on the sheet P by the image forming unit 33.

[0057] Although not particularly shown, a plurality of conveyance rollers, a calibration unit, conveyance guide rollers, etc. are provided in the vicinity of the colorimeter 43, similar to the image reading unit 42. Therefore, shock noise also occurs during reading by the colorimeter 43.

[0058] The sheet detection sensor SE1 is provided on the upstream side in the conveyance direction of the sheet P from each reading unit. Each reading unit includes a surface image reading unit 42b, a back surface image reading unit 42a, and a colorimeter 43. The sheet detection sensor SE1 is, for example, an optical sensor that optically detects the passing sheet P. That is, the sheet detection sensor SE1 can detect that the leading edge of the passing sheet P has arrived.

[0059] Next, the control of the image forming system 1 according to the present embodiment will be described with reference to the flowchart of FIG. 6. The control of FIG. 6 is started when the control unit 31 of the image forming apparatus 30 acquires a print job from an external device or the like via the communication unit 36. The control unit 31 controls the paper feeding device 10. The control unit 31 also controls the paper information detection device 20 via the control unit 21. The control unit 31 also controls the image reading device 40 via the control unit 41.

[0060] In the present embodiment, the paper thickness sensor 231, the moisture content sensor 232, and the basis weight sensor 233 are disposed on the conveyance path R21 connected to the image forming apparatus 30. Therefore, it is possible to detect the physical property values of the sheet P during the execution of the print job. Thus, the conveyance speed in the reading unit can be controlled in real time for each sheet P for which the physical property values have been detected. On the other hand, the stiffness sensor 224 detects the stiffness of the paper P by reading the force applied to the bent paper P. That is, since the paper P whose stiffness has been detected by the stiffness sensor 224 cannot be used as a product, it is discharged to the purge tray T20. Therefore, during the execution of the printing job, the physical property values of the paper P cannot be detected. Thus, it is necessary to detect the stiffness of the paper P before the execution of the printing job and use the value to control the conveyance speed in the reading unit during the execution of the printing job. In the present embodiment, the control unit 31 causes the stiffness sensor 234 to detect the stiffness of the paper P before the execution of the printing job. Hereinafter, the control of the image forming system 1 will be described with reference to FIG. 6.

[0061] First, the control unit 31 determines whether the stiffness detection mode is ON (step S101). The stiffness detection mode is a mode in which the stiffness of the paper P is detected before the execution of the printing job and the detected stiffness is used for the conveyance speed control in the reading unit during the execution of the printing job. When the control unit 31 determines that the stiffness detection mode is ON (step S101: YES), it proceeds to the next step S102. On the other hand, when the control unit 31 determines that the stiffness detection mode is not ON (OFF) (step S101: NO), it proceeds to step S107.

[0062] Next, the control unit 31 switches the conveyance path of the paper P from the conveyance path R21 to the stiffness detection path R22 (step S102).

[0063] Next, the control unit 31 controls the paper feeder 10 to start feeding the paper P (step S103).

[0064] Next, the control unit 31 acquires the stiffness of the paper P detected by the stiffness sensor 224 (step S104).

[0065] Next, the control unit 31 stores the stiffness of the paper P acquired in step S104 in the storage unit 32 (step S105).

[0066] Next, the control unit 31 causes the paper P whose stiffness has been detected by the stiffness sensor 224 to be discharged to the purge tray T20 (step S106).

[0067] Next, the control unit 31 starts executing the print job (step S107).

[0068] Next, the control unit 31 reads out the paper conveyance speed table TA1 stored in the storage unit 32 (step S108).

[0069] Next, the control unit 31 controls the paper feeding device 10 to start feeding the paper P (step S109).

[0070] Next, the control unit 31 acquires the physical property values of the paper P detected by the media sensor 23 disposed on the conveyance path R21 (step S110). Specifically, the paper thickness, basis weight, and moisture content respectively detected by the paper thickness sensor 231, moisture content sensor 232, and basis weight sensor 233 are acquired.

[0071] Next, the control unit 31 determines whether it is necessary to change the conveyance speed of the paper P in the reading unit (step S111). Specifically, first, the control unit 31 collates the stiffness acquired in step S104 and the physical property values acquired in step S110 with the paper conveyance speed table TA1 to extract (determine) the target value of the conveyance speed. Next, the control unit 31 compares the current conveyance speed with the extracted target value to determine whether it is necessary to change the conveyance speed. If the control unit 31 determines that it is necessary to change the conveyance speed (step S111: YES), it proceeds to the next step S112. On the other hand, if the control unit 31 determines that it is not necessary to change the conveyance speed (step S111: NO), it proceeds to step S113.

[0072] In step S112, the control unit 31 decelerates the conveyance speed of the paper P in the reading unit to the target value. Then, it proceeds to step S113.

[0073] As described above, the control unit 31 controls the conveyance speed of the sheet P during the execution of the print job according to at least one of the physical property values of the sheet P detected by the media sensor 23 disposed on the conveyance path R21. Specifically, the conveyance speed of the sheet P is controlled during the execution of the print job according to at least one of the sheet thickness, moisture content, and basis weight of the sheet P.

[0074] In the present embodiment, the control unit 31 controls the conveyance speed of the sheet P until the reference image for image adjustment formed on the sheet P enters the reading unit. Alternatively, the control unit 31 controls the conveyance speed of the sheet P until the leading edge of the sheet P enters the reading unit.

[0075] FIG. 7 is a diagram for explaining the timing of changing the conveyance speed of the sheet P. The solid line F1 shows an example of the conveyance speed when the conveyance speed is controlled until the reference image enters the reading unit. The broken line F2 shows an example of the conveyance speed when the conveyance speed is controlled until the leading edge of the sheet P enters the reading unit. In the example shown in FIG. 7, it can be seen that the deceleration time of the solid line F1 is relatively shorter than that of the broken line F2.

[0076] The state where the sheet detection sensor SE1 is ON indicates that the sheet P passing through the sheet detection sensor SE1 provided upstream in the conveyance direction from the reading unit is being detected. That is, the timing at which the sheet detection sensor SE1 switches from OFF to ON indicates that the leading edge of the sheet P is being detected. In the example shown by the broken line F2, it can be seen that the conveyance speed becomes slower before the timing at which the sheet detection sensor SE1 switches from OFF to ON.

[0077] The reference image position is the position of the reference image for image adjustment formed on the sheet P. The symbol H1 at the reference image position indicates that the reference image formed on the leading edge side of the sheet P has reached the reading position of the reading unit. The symbol H2 at the reference image position indicates that the reference image formed on the trailing edge side of the sheet P has reached the reading position of the reading unit. In the example shown by the solid line F1, it can be seen that the conveyance speed is slower before the timing when the reference image formed on the leading edge side of the sheet P reaches the reading position (enters the reading unit).

[0078] When controlling the conveyance speed until the reference image enters the reading unit, the deceleration time can be relatively shortened, so the productivity of image printing can be improved. On the other hand, when controlling the conveyance speed until the leading edge of the sheet P enters the reading unit, the start of deceleration can be relatively advanced, so the image can be read in a state where the sheet posture is stable.

[0079] In step S113, the control unit 31 determines whether the printing job has ended. When the control unit 31 determines that the printing job has ended (step S113: YES), the process ends as it is. On the other hand, when the control unit 31 determines that the printing job has not ended (step S113: NO), it shifts to step S110. Thereafter, the process is repeated until the printing job ends. That is, the conveyance speed can be controlled in real time for each sheet P for which physical property values (paper thickness, basis weight, moisture content) have been acquired.

[0080] In the present embodiment, the control unit 31 controls the conveyance speed when the reading unit reads the reference image for image adjustment formed on the sheet P. The reference image for image adjustment includes, in addition to the reference image G1 for position adjustment read by the image reading unit 42, a patch image read by the colorimeter 43.

[0081] As described above, the image forming system 1 according to the present embodiment includes an image forming unit 33, a reading unit (image reading unit 42, colorimeter 43), and a control unit 31. The image forming unit 33 forms an image on a sheet. The reading unit reads the image formed on the sheet by the image forming unit 33. The control unit 31 controls the conveyance speed of the sheet in the reading unit according to the physical property value of the sheet. Therefore, according to the image forming system 1 according to the present embodiment, the influence of shock noise can be reduced. In particular, it is possible to reduce the influence of shock noise on a sheet whose reading accuracy is reduced due to the influence of shock noise. Thereby, it is possible to sufficiently ensure the accuracy of reading by the reading unit. In addition, high-quality printed matter can be generated without sacrificing productivity for normal paper that is not affected by shock noise. In addition, since there is no limitation on the position where the reference image is formed, various reference images can be accurately read. In addition, since a mechanism for moving the conveyance roller is not required, it is possible to sufficiently ensure the accuracy of reading without increasing the cost. From the above, it is possible to generate high-quality printed matter without providing a limitation on the formation position of the reference image and without increasing the cost.

[0082] It also includes a media sensor 23 that detects physical property values. The control unit 31 controls the conveyance speed according to the physical property value detected by the media sensor 23. Therefore, it is possible to detect the physical property value of the actually conveyed sheet and control the conveyance speed. Therefore, it is possible to more accurately reduce the influence of shock noise.

[0083] The media sensor 23 is disposed upstream of the image forming unit 33 in the sheet conveyance direction. Therefore, the physical property value of the sheet can be detected before the image is read by the reading unit. Therefore, the image formed on the sheet whose physical property value has been detected can be accurately read inline.

[0084] Further, it includes an adjustment unit (control unit 31) that adjusts the image formation position of the sheet according to the reading result obtained by reading a reference image for position adjustment formed on the sheet by a reading unit. The adjustment unit adjusts the image formation positions on the front and back of the sheet. Therefore, the image formation positions on the front and back of the sheet can be accurately adjusted. Thus, the quality of the printed matter can be improved.

[0085] Also, the control unit 31 controls the conveyance speed when the reading unit reads a reference image for image adjustment formed on the sheet. Therefore, sufficient accuracy of reading by the reading unit can be ensured. Thus, high-quality printed matter can be generated.

[0086] Also, the control unit 31 slows down the conveyance speed as the stiffness detected by the stiffness sensor 234 is higher. The control unit 31 slows down the conveyance speed as the paper thickness detected by the paper thickness sensor 231 is thicker. The control unit 31 slows down the conveyance speed as the moisture content detected by the moisture content sensor 232 is lower. The control unit 31 slows down the conveyance speed as the basis weight detected by the basis weight sensor 233 is larger. Therefore, for a sheet whose reading accuracy is reduced due to the influence of shock noise, the influence of shock noise can be reduced. Thereby, sufficient accuracy of reading by the reading unit can be ensured. Thus, high-quality printed matter can be generated.

[0087] Also, the control unit 31 causes the stiffness sensor 234 to detect the stiffness before executing a print job. Therefore, after discharging the sheet that has been bent during the detection of stiffness to the purge tray T20, the print job can be executed. Thus, it is possible to prevent wavy paper from being mixed in the printed matter.

[0088] Also, the control unit 31 controls the conveyance speed during the execution of a print job according to at least any one of the paper thickness detected by the paper thickness sensor 231, the moisture content detected by the moisture content sensor 232, and the basis weight detected by the basis weight sensor 233. Therefore, during the execution of a printing job, an image formed on a sheet whose physical property value has been detected can be accurately read inline. Thus, the productivity of image printing can be improved.

[0089] In addition, the control unit 31 controls the conveyance speed until a reference image for image adjustment formed on the sheet enters the reading unit. Therefore, the deceleration time of the conveyance speed can be relatively shortened. Thus, the productivity of image printing can be improved.

[0090] In addition, the control unit 31 controls the conveyance speed until the leading edge of the sheet enters the reading unit. Therefore, the start of deceleration of the conveyance speed can be relatively advanced. Thus, an image can be read in a state where the sheet posture is stable.

[0091] As described above, specific explanations have been made based on the embodiments according to the present invention. However, the present invention is not limited to the above embodiments and can be modified without departing from the gist thereof.

[0092] For example, in the above embodiment, the physical property value detected by the media sensor 23 is acquired, but the present invention is not limited thereto. The physical property value may be acquired based on the sheet information set by the user via the operation display unit 34. That is, the control unit 31 acquires the physical property values (stiffness, paper thickness, moisture content, basis weight) of the sheet P based on the sheet information such as the sheet type, basis weight, and size of the sheet P. In this case, the control unit 31 functions as an acquisition unit of the present invention. Then, the control unit 31 controls the conveyance speed of the sheet P in the reading unit according to the acquired physical property values.

[0093] In the above-described embodiment, the media sensor 23 is exemplified as including the stiffness sensor 234, the paper thickness sensor 231, the moisture content sensor 232, and the basis weight sensor 233, but the present invention is not limited thereto. The media sensor 23 may include at least one of the stiffness sensor 234, the paper thickness sensor 231, the moisture content sensor 232, and the basis weight sensor 233.

[0094] In the above-described embodiment, the media sensor 23 is arranged upstream of the image forming unit 33 in the conveyance direction of the sheet P, but the present invention is not limited thereto. For example, the media sensor 23 may be arranged downstream of the image forming unit 33 in the conveyance direction of the sheet P and upstream of the image reading unit 42 in the conveyance direction of the sheet P. That is, the paper information detection device 20 may be arranged between the image forming apparatus 30 and the image reading apparatus 40. By arranging the paper information detection device 20 between the image forming apparatus 30 and the image reading apparatus 40, the conveyance speed of the sheet can be controlled based on the physical property values of the sheet P after image formation. Thereby, the influence of shock noise can be further reduced. Therefore, the accuracy of reading by the reading unit can be further improved.

[0095] In addition, regarding the detailed configuration of each device constituting the image forming system and the detailed operation of each device, it can be appropriately changed without departing from the spirit of the present invention.

Explanation of Reference Numerals

[0096] 1 Image forming system 10 Paper feeding device 11 Paper feeding tray 20 Paper information detection device 21 Control unit 22 Conveyance unit 23 Media sensor 231 Paper thickness sensor 232 Moisture content sensor 233 Basis weight sensor 234 Stiffness sensor T20 Purge tray R21 Conveyor path R22 Stiffness detection path 30 Image forming apparatus 31 Control unit (adjustment unit, acquisition unit) 32 Memory unit 33 Image forming unit 34 Operation display unit (setting unit) 35 Conveyor unit 36 Communication unit T30 Paper feed tray 40 Image reading apparatus 41 Control unit 42 Image reading unit (reading unit) 42a Backside image reading unit 421 CCD 422 Optical system 423 LED light source 424 Calibration unit 42b Front side image reading unit 43 Colorimeter (reading unit) 44 Conveyor roller 45 First conveyor guide roller 46 Second conveyor guide roller R40 Conveyor path P Paper

Claims

1. An image forming unit that forms an image on a sheet, A reading unit that reads the image formed on the sheet by the image forming unit, A control unit that controls the conveyance speed of the sheet in the reading unit according to the physical property value of the sheet, An image forming system characterized by comprising the above.

2. Comprising a media sensor that detects the physical property value, The control unit controls the conveyance speed according to the physical property value detected by the media sensor. The image forming system according to Claim 1.

3. The media sensor includes at least one of a stiffness sensor that detects the stiffness of the sheet, a paper thickness sensor that detects the paper thickness of the sheet, a moisture content sensor that detects the moisture content of the sheet, and a basis weight sensor that detects the basis weight of the sheet. The image forming system according to Claim 2.

4. The media sensor is disposed upstream of the image forming unit in the conveyance direction of the sheet. The image forming system according to Claim 2.

5. The media sensor is disposed downstream of the image forming unit in the conveyance direction of the sheet and upstream of the reading unit in the conveyance direction of the sheet. The image forming system according to Claim 2.

6. An adjustment unit that adjusts the image forming position of the sheet according to a reading result obtained by reading a reference image for position adjustment formed on the sheet by the reading unit. The image forming system according to Claim 1.

7. The adjustment unit adjusts the image forming positions on the front and back of the sheet. The image forming system according to Claim 6.

8. The control unit controls the conveyance speed when the reading unit reads a reference image for image adjustment formed on the sheet. The image forming system according to Claim 1.

9. Comprising an acquisition unit that acquires the physical property value based on sheet information set by a user via a setting unit, The control unit controls the conveyance speed according to the physical property value acquired by the acquisition unit. The image forming system according to Claim 1.

10. The higher the stiffness detected by the stiffness sensor, the slower the control unit sets the conveyance speed. The image forming system according to Claim 3.

11. The image forming system according to claim 3, wherein the control unit slows down the conveyance speed as the paper thickness detected by the paper thickness sensor is thicker.

12. The image forming system according to claim 3, wherein the control unit slows down the conveyance speed as the moisture content detected by the moisture content sensor is lower.

13. The image forming system according to claim 3, wherein the control unit slows down the conveyance speed as the basis weight detected by the basis weight sensor is larger.

14. The media sensor includes a stiffness sensor that detects the stiffness of the paper, The image forming system according to claim 2, wherein the control unit causes the stiffness sensor to detect the stiffness before executing a print job.

15. The media sensor includes a paper thickness sensor that detects the paper thickness of the paper, a moisture content sensor that detects the moisture content of the paper, and a basis weight sensor that detects the basis weight of the paper. The image forming system according to claim 2, wherein the control unit controls the conveyance speed during execution of a print job according to at least any one of the paper thickness detected by the paper thickness sensor, the moisture content detected by the moisture content sensor, and the basis weight detected by the basis weight sensor.

16. The image forming system according to claim 1, wherein the control unit controls the conveyance speed until a reference image for image adjustment formed on the paper enters the reading unit.

17. The image forming system according to claim 1, wherein the control unit controls the conveyance speed until the leading edge of the paper enters the reading unit.

18. A conveyance speed control method for an image forming system including an image forming unit that forms an image on a paper and a reading unit that reads the image formed on the paper by the image forming unit, The conveyance speed control method includes a control step of controlling the conveyance speed of the paper in the reading unit according to the physical property value of the paper.

19. A program for causing a computer of an image forming system including an image forming unit that forms an image on a paper and a reading unit that reads the image formed on the paper by the image forming unit to function as a control unit that controls the conveyance speed of the paper in the reading unit according to the physical property value of the paper. ​

Images