Image forming apparatus, control method for image forming apparatus, and control program for image forming apparatus

Abstract

To provide an image forming apparatus capable of detecting floating of a sheet by a simple method.SOLUTION: An image forming apparatus comprises a sheet conveyance mechanism in which a sheet provided with a plurality of holes is attached onto a conveyance surface, an image reading part for reading the sheet on the conveyance surface of the sheet conveyance mechanism to output a reading image, a feature amount extraction part for extracting a feature amount in association with floating of the sheet from the reading image of the sheet, and a floating detection part for detecting floating of the sheet based on an extraction result.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to an image forming apparatus. [Background technology]

[0002] Image forming devices for industrial applications are required to print on a variety of media types (white paper, black paper, colored paper, transparent film, etc.). One-pass inkjet image forming devices feature non-contact printing and high-speed image formation. Because high image quality is required for these devices, an inline sensor is installed downstream of the printing process to read the image on the media and measure ink position accuracy and gradation stability. To ensure consistent image quality, an appropriate distance must be maintained between the inkjet head and the paper surface. While a small gap improves printing accuracy, it increases the risk of ink jetting failure or damage due to contact with the media. On the other hand, a large gap prevents contact with the media, but reduces ink droplet placement accuracy, resulting in a trade-off between image quality and productivity. Generally, the gap is set to approximately 1 mm to 1.5 mm, balancing high image quality with productivity. Furthermore, to maintain the printing conditions of the device, heating is required to control the inkjet head, paper, and drum to their optimum temperatures, and in some cases a layer (e.g., a PFA sheet) is provided between the drum and paper to prevent heat transfer due to their interaction. The sheet is attached to the drum surface with a certain amount of tension so that it adheres tightly, and the paper is placed on top of it and transported, but repeated expansion and contraction due to heat can deteriorate the sheet, causing it to lose adhesion and float from the drum surface, which can cause the sheet itself to come into contact with the inkjet head.

[0003] Once a floating occurs, the inkjet head continues to come into contact with the surface that is not being used for paper transport while the drum is rotating, which can significantly shorten the life of the inkjet head. Even if the floating does not come into contact with the inkjet head, there is a problem that the paper may indirectly come into contact with the inkjet head during the paper transport process when it is transported in correspondence with the floating sheet surface.

[0004] The sheet is a type of fluororesin that functions to suppress heat transfer and features uniformly shaped holes on its surface at regular intervals to prevent air from being drawn into the drum, thereby preventing interference with the drum's paper transport function. This can lead to ink mist and other contaminants adhering to the sheet surface, resulting in both floatation and contamination. The sheet is manufactured by pressing the resin with a roller to a specified thickness, and then creating holes using a press. This processing method results in a sheet that is the same thickness as or thinner than the paper, resulting in a surface irregularity with different cross-sections of the sheet surface and the holes. When the sheet is pressed against the drum surface, the sheet surface covers the drum surface, but the holes do not obscure it. Therefore, these factors must be considered separately from paper floatation when detecting floatation.

[0005] Furthermore, after the sheet lift is detected, a service technician or operator must identify the cause of the lift and take appropriate measures. At this time, it is necessary to accurately identify the location of the lift on the drum surface, which has a large printing area, and take appropriate measures. If these tasks cannot be performed efficiently, the device's downtime will increase, resulting in a loss of productivity, which is important for industrial printers.

[0006] In this regard, there is a technology that uses an optical sensor to detect floating of a sheet-like medium, thereby preventing damage to the device (see Patent Document 1). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2018-193171 Summary of the Invention [Problem to be solved by the invention]

[0008] However, this technology requires the addition of a dedicated sensor, and its placement must be precisely adjusted relative to the drum surface. Furthermore, a special mechanism for scanning the sensor is required to determine the sheet height using a single sensor. Furthermore, applying such a mechanism to a sheet placed on a curved cylinder is structurally inappropriate.

[0009] The present disclosure has been made in consideration of the above-described background, and aims to provide an image forming apparatus, a control method for an image forming apparatus, and a control program for an image forming apparatus that can detect sheet floating using a simple method. [Means for solving the problem]

[0010] The image forming apparatus of the present disclosure includes a paper transport mechanism on which a sheet having multiple holes is attached to a transport surface, an image reading unit that reads the sheet on the transport surface of the paper transport mechanism and outputs a read image, a feature extraction unit that extracts features related to sheet floating from the read image of the sheet, and a floating detection unit that detects sheet floating based on the extraction results.

[0011] Preferably, the feature extraction unit includes a surface image extraction unit that extracts an image of the surface region of the sheet from the read image of the conveyance surface, and a noise removal unit that removes a noise region from the image of the surface region of the sheet.

[0012] Preferably, the feature extraction unit includes a gradation level detection unit that detects a change in gradation level of the extracted image of the surface region of the sheet as the feature relating to the lifting of the sheet.

[0013] Preferably, the feature extraction unit includes an area discrimination unit that discriminates a first area representing a hole from the image and a second area other than the hole, and the gradation level detection unit detects a change in gradation level in the main scanning or sub-scanning direction of the second area of ​​the image.

[0014] Preferably, the noise removal unit extracts color information of the image, and removes a noise area in which a predetermined color is identified from the image of the surface area of ​​the sheet based on the extracted color information.

[0015] Preferably, the noise removal unit includes a periodicity calculation unit that calculates periodic characteristics of gradation levels according to the arrangement of a first region indicating a hole in the main scanning or sub-scanning direction and a second region other than that, and an area removal unit that removes, as noise areas, areas from the image of the surface area of ​​the sheet that show characteristics different from the calculated periodicity of gradation levels.

[0016] Preferably, the lift detection unit determines whether or not the gradation level or the amount of change in gradation level detected by the gradation level detection unit exceeds a predetermined value.

[0017] Preferably, the lift detection unit determines whether the gradation level or the amount of change in gradation level detected by the gradation level detection unit exceeds a predetermined value continuously in the main scanning or sub-scanning direction.

[0018] Preferably, the feature extraction unit includes an area discrimination unit that discriminates a first area indicating a hole from the image and a second area other than the hole, and an area calculation unit that calculates the area of ​​the first area as a feature related to the lifting of the sheet.

[0019] Preferably, the feature extraction unit further includes a boundary area discrimination unit that discriminates a boundary area between the first area and the second area, the boundary area indicating a cross-sectional portion of the first area, and the area calculation unit calculates the area of ​​the boundary area between the first area and the second area as a feature related to the lifting of the sheet.

[0020] Preferably, the image forming apparatus further includes an image forming unit that executes a printing operation, and the image forming unit stops the printing operation based on the detection result of the lift detection unit.

[0021] Preferably, the image forming apparatus further includes a combining unit that combines the lifted area detected by the lift detection unit with the read image of the conveyance surface.

[0022] Preferably, the device further includes a memory unit that stores multiple amounts of float detected by the float detection unit in chronological order, and a prediction unit that predicts the time required to reach a predetermined amount of float based on the amount of float stored in the memory unit.

[0023] Preferably, the device further comprises a prediction notification unit that notifies the prediction result of the prediction unit.

[0024] Preferably, the prediction notification unit displays the prediction result on the display unit or transmits the prediction result via the communication unit to an external server connected to the communication unit.

[0025] Preferably, the device further includes a result notification unit that notifies the detection result of the lift detection unit.

[0026] Preferably, the result notification unit displays the detection result on the display unit, or transmits the detection result via the communication unit to an external server connected to the communication unit.

[0027] Preferably, the lift detection unit detects the lift of the sheet in association with a position on the sheet.

[0028] Preferably, the image reading unit reads the sheet and outputs a planar read image.

[0029] Preferably, the paper transport mechanism transports the paper by sucking air through a plurality of holes.

[0030] The present disclosure provides a control method for an image forming device having a paper transport mechanism on whose transport surface a sheet having a plurality of holes is attached, the control method comprising the steps of: reading a sheet on the transport surface of the paper transport mechanism and outputting a read image; extracting features related to sheet floating from the read image of the sheet; and detecting sheet floating based on the extraction results.

[0031] A control program for an image forming device having a paper transport mechanism with a sheet having multiple holes attached to its transport surface, the computer of the image forming device executing the control program includes steps of reading a sheet on the transport surface of the paper transport mechanism and outputting a read image, extracting features related to sheet floating from the read image of the sheet, and detecting sheet floating based on the extraction results. [Brief explanation of the drawings]

[0032] [Figure 1] 1 is a diagram schematically illustrating the overall configuration of an image forming apparatus 10 based on an embodiment. [Figure 2] 1 is a schematic side view showing the internal structure of an image forming apparatus 10 based on an embodiment. [Figure 3] 3 is a schematic side view showing an enlarged view of a part of the image forming unit 12 shown in FIG. 2. FIG. [Figure 4] FIG. 1 is a functional block diagram of an image forming apparatus 10 based on an embodiment. [Figure 5] 1A and 1B are diagrams illustrating a sheet based on an embodiment. [Figure 6] 10A and 10B are diagrams illustrating the problem of the sheet 27 floating. [Figure 7] 1A to 1C are diagrams illustrating an overview of a method for detecting sheet lift according to an embodiment. [Figure 8] FIG. 10 is a flowchart illustrating a process for detecting sheet lift based on an embodiment. [Figure 9] FIG. 10 is a flowchart illustrating a subroutine process of the image acquisition process based on the embodiment. [Figure 10] FIG. 10 is a flow diagram illustrating a subroutine process of preprocessing based on the embodiment. [Figure 11] FIG. 10 is a flow diagram illustrating a subroutine process for identifying a target area based on an embodiment. [Figure 12] FIG. 10 is a flow diagram illustrating a subroutine process for identifying an exclusion area based on an embodiment. [Figure 13]10A to 10C are diagrams illustrating an extraction process for noise removal based on an embodiment. [Figure 14] FIG. 10 is a flowchart illustrating a subroutine process of feature extraction processing (part 1) according to the embodiment. [Figure 15] 10 is a diagram illustrating a change area of ​​the gradation level detected by the gradation level detection unit 122. FIG. [Figure 16] FIG. 10 is a flowchart illustrating a subroutine process of a feature extraction process (part 2) according to an embodiment. [Figure 17] FIG. 10 is a flowchart illustrating a subroutine process of a feature extraction process (part 3) according to an embodiment. [Figure 18] FIG. 10 is a flowchart illustrating a subroutine process of the floating detection process according to the embodiment. [Figure 19] 10A and 10B are diagrams illustrating a floating determination process. [Figure 20] FIG. 10 is a diagram illustrating the ranking of floatation. [Figure 21] FIG. 10 is a flowchart illustrating a subroutine process of a notification process according to an embodiment. [Figure 22] FIG. 10 is a flowchart illustrating a subroutine process of print control according to the embodiment. [Figure 23] FIG. 10 is a diagram illustrating a screen displaying a determination result of a result notifying unit 150 according to the embodiment. [Figure 24] 10A and 10B are diagrams illustrating a case where a second warning is displayed on display unit 105 according to an embodiment. [Figure 25] 10A and 10B are diagrams illustrating data relating to the amount of lift detected by lift detection unit 130 according to the embodiment. [Figure 26] 10A and 10B are diagrams illustrating prediction of the amount of lifting in a prediction unit 170 according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0033] Each embodiment will be described below with reference to the drawings. In the following description, the same parts and components are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed descriptions thereof will not be repeated. Note that the embodiments and modifications described below may be selectively combined as appropriate.

[0034] FIG. 1 is a diagram schematically illustrating the overall configuration of an image forming apparatus 10 according to an embodiment. Referring to FIG. 1, the image forming apparatus 10 is an inkjet recording apparatus that forms (records) an image on paper by ejecting ink from multiple nozzles. The image forming apparatus 10 may be a color image forming apparatus or a monochrome image forming apparatus. In this embodiment, the image forming apparatus 10 will be described as a color image forming apparatus. The image forming apparatus 10 is an apparatus that forms an image on paper using a single-pass inkjet method. The single-pass inkjet method is a method of forming an image without moving a recording head unit having multiple nozzles in the main scanning direction. The main scanning direction is a direction perpendicular to the sub-scanning direction. The sub-scanning direction is a direction parallel to the paper transport direction. The single-pass inkjet method is capable of forming an image on a recording medium without contacting the recording medium and at high speed.

[0035] The image forming apparatus 10 comprises a paper feed unit 11, an image forming unit 12, a paper discharge unit 13, and an ink supply tank 14. The paper feed unit 11 is a unit that supplies paper as a recording medium. The image forming unit 12 is a unit that forms an image on paper using ink. The paper discharge unit 13 is a unit that discharges paper after the image has been formed on it. The ink supply tank 14 is a tank that stores a predetermined amount of ink and supplies this ink to the image forming unit 12.

[0036] FIG. 2 is a schematic side view showing the internal structure of an image forming apparatus 10 according to an embodiment. Referring to FIG. 2, the aforementioned main scanning direction of the image forming apparatus 10 corresponds to the depth direction in FIG. 2. The paper feed unit 11 includes a paper feed tray 11a. Paper sheets 15 before images are formed or test sheets with a predetermined pattern or image formed thereon are stacked in the paper feed tray 11a. The paper feed unit 11 separates and supplies the paper sheets 15 stacked in the paper feed tray 11a one by one, starting from the top. The image forming unit 12 includes a transport drum 20 as a transport unit, multiple recording head units 21Y, 21M, 21C, and 21K, a mist catcher 22, an ultraviolet light irradiation unit 23, an image reading unit 24, an inverting unit 25, and two large and small transport rollers 26a and 26b. The transport drum 20 is rotatable.

[0037] The transport drum 20 rotates while wrapping the paper 15 supplied from the paper feed unit 11 around its outer circumferential surface 20a. The transport drum 20, for example, uses air suction to adhere the paper 15 to the outer circumferential surface 20a of the transport drum 20, and transports the paper 15 in the transport direction A by rotating in this state. To achieve this transport method, multiple air suction holes (not shown) are formed in the outer circumferential surface 20a of the transport drum 20. The multiple recording head units 21Y, 21M, 21C, and 21K form (record) images on the paper 15, which serves as a recording medium, using ink of a corresponding color. Specifically, the recording head unit 21Y forms images using yellow (Y) ink, and the recording head unit 21M forms images using magenta (M) ink. The recording head unit 21C forms images using cyan (C) ink, and the recording head unit 21K forms images using black (K) ink. In this embodiment, ultraviolet-curable inks are used as an example. Each of the recording head units 21Y, 21M, 21C, and 21K is disposed facing the upper outer peripheral surface 20a of the transport drum 20. Each of the recording head units 21Y, 21M, 21C, and 21K is disposed at a different position in the circumferential direction of the transport drum 20. In this embodiment, as an example, four recording head units 21Y, 21M, 21C, and 21K are provided in the image forming section 12.

[0038] The mist catcher 22 is disposed downstream of the recording head unit 21K in the transport direction A of the paper 15 by the transport drum 20. The mist catcher 22 collects mist generated by ink ejection from the inkjet heads provided in each of the recording head units 21Y, 21M, 21C, and 21K. The ultraviolet irradiator 23 is disposed downstream of the mist catcher 22 in the transport direction A of the paper 15. The ultraviolet irradiator 23 cures the ink on the paper 15 by irradiating the paper 15 with ultraviolet light as it is transported by the rotation of the transport drum 20. The ink on the paper 15 referred to here refers to the ink forming an image on the paper 15. The ultraviolet irradiator 23 functions as a fixing unit that fixes the image formed on the paper 15 using ink to the paper 15. Fixing of the image by the fixing unit is not limited to irradiation with ultraviolet light, but may also involve irradiating energy rays capable of curing the ink depending on the properties of the ink, or heating the paper 15 to dry the ink.

[0039] The image reading unit 24 uses an inline sensor. The inline sensor is located downstream of the ultraviolet irradiation unit 23 in the conveyance direction A of the paper 15. The image reading unit 24 reads the image-formed surface of the paper 15 using a reduction optical system. The image-formed surface of the paper 15 refers to the surface of the paper 15 that faces each of the recording head units 21Y, 21M, 21C, and 21K when the paper 15 is adsorbed and conveyed by the conveyance drum 20. An image is formed on the image-formed surface of the paper 15 using each of the recording head units 21Y, 21M, 21C, and 21K. The reversing unit 25 reverses the paper 15 so that images can be formed on both sides of the paper 15 or so that the paper 15 can be discharged with an image formed on one side of the paper 15 facing downward. The conveyance rollers 26a and 26b convey the paper 15, after the image has been formed, toward the paper discharge unit 13. The paper discharge unit 13 has a paper discharge tray 13a. The paper sheets 15 on which images have been formed are sequentially discharged onto the paper discharge tray 13a.

[0040] FIG. 3 is a schematic side view of an enlarged portion of the image forming unit 12 shown in FIG. 2. In the following description, the suffixes Y, M, C, and K representing ink colors will be omitted unless it is necessary to distinguish the individual recording head units 21Y, 21M, 21C, and 21K and their components by ink color. Referring to FIG. 3, a transport path 31 (shown by a dashed line in the figure) for transporting the recording medium is formed on the outer circumferential surface 20a of the transport drum 20. Paper 15 (see FIG. 2) as a recording medium is attracted to the outer circumferential surface 20a of the transport drum 20 and transported in accordance with the rotation of the transport drum 20. Therefore, the transport path 31 is formed along the outer circumferential surface 20a of the transport drum 20. Image recording positions P1, P2, P3, P4, and P5 for the individual recording head units 21Y, 21M, 21C, and 21K are located along the transport path 31. Image recording position P1 is a position where an image is recorded (formed) by recording head unit 21Y, and image recording position P2 is a position where an image is recorded by recording head unit 21M. Image recording position P3 is a position where an image is recorded by recording head unit 21C, and image recording position P4 is a position where an image is recorded by recording head unit 21K. As paper 15 is transported along transport path 31, the leading edge of paper 15 first passes image recording position P1, where recording head unit 21Y records the image, and then passes image recording positions P2, P3, and P4, where recording head units 21M, 21C, and 21K record the image, in that order. When ink is ejected from each of the four recording head units 21Y, 21M, 21C, and 21K at a predetermined timing, yellow ink adheres to paper 15 at image recording position P1, and magenta ink adheres to paper 15 at image recording position P2. Furthermore, cyan ink is deposited on the paper 15 at image recording position P3, and black ink is deposited on the paper 15 at image recording position P4. The recording head unit 21Y includes an inkjet head 32Y and a carriage 33Y that holds the inkjet head 32Y. The inkjet head 32Y has an ink ejection surface 34Y, and ejects ink from nozzles provided on the ink ejection surface 34Y. The ink ejection surface 34Y of the inkjet head 32Y is disposed so as to face the outer peripheral surface 20a of the transport drum 20.When forming an image on paper 15 with inkjet head 32Y, nozzles are selected in accordance with image data specified in a print job, and ink is ejected from the selected nozzles toward paper 15. Similar to recording head unit 21Y described above, recording head unit 21M includes inkjet head 32M and carriage 33M that holds inkjet head 32M. Furthermore, recording head unit 21C includes inkjet head 32C and carriage 33C that holds inkjet head 32C, and recording head unit 21K includes inkjet head 32K and carriage 33K that holds inkjet head 32K.

[0041] 4 is a functional block diagram of image forming apparatus 10 based on the embodiment. Referring to FIG. 4, image forming apparatus 10 includes paper feed unit 11, ink supply tank 14, paper discharge unit 13, image forming unit 12, and control unit 100.

[0042] The image reading unit 24 reads the sheet on the conveying surface, which is the image forming surface of the paper conveying mechanism (conveying drum 20), and outputs the flat read image to the control unit 100.

[0043] The control unit 100 includes a central processing unit (CPU) 101, a read only memory (ROM) 102, a random access memory (RAM) 103, a communication unit 104, and the like.

[0044] The CPU 101 reads out a program corresponding to the processing content from the ROM 102, loads it into the RAM 103, and centrally controls the operations of each block of the image forming apparatus 10 in cooperation with the loaded program.

[0045] The ROM 102 and RAM 103 are configured by, for example, a nonvolatile semiconductor memory (so-called flash memory) or a hard disk drive.

[0046] ROM 102 and RAM 103 store programs executed by CPU 101 and various data used to execute the programs. At least one of the programs and data may be stored in a storage device (such as an external server) other than control unit 100, as long as the storage device is accessible by CPU 101.

[0047] The processing in the control unit 100 is realized by each piece of hardware and software executed by the control unit 100. Such software may be pre-stored in the ROM 102 and RAM 103. The software may also be stored on a CD-ROM or other recording medium and distributed as a computer program. Alternatively, the software may be provided as a downloadable application program by an information provider connected to the Internet. Such software is read from the recording medium by an optical disk drive or other reading device, or downloaded via the communication unit 104, and then temporarily stored in the RAM 103. The software is read from the RAM 103 by the CPU 101 and stored in the RAM 103 in the form of an executable program. The control unit 100 executes the program.

[0048] The control unit 100 transmits and receives various data to and from external devices (e.g., personal computers, external servers) connected to a communication network such as a LAN (Local Area Network) or WAN (Wide Area Network) via the communication unit 104. The control unit 100 receives, for example, image data transmitted from an external device, and forms an image on paper S based on this image data (input image data). The communication unit 104 is configured, for example, by a communication control card such as a LAN card.

[0049] The CPU 101 implements various functional blocks by reading and executing programs. Specifically, the CPU 101 includes a feature extraction unit 110, a lift detection unit 130, a synthesis unit 140, a result notification unit 150, a prediction notification unit 160, a prediction unit 170, and an image adjustment unit 180.

[0050] The image adjustment unit 180 performs preprocessing on the image data acquired by the image reading unit 24. Specifically, it performs resolution conversion, tone value correction, and the like.

[0051] The feature extraction unit 110 extracts feature amounts related to the floating of the sheet from the scanned image of the sheet. The sheet has holes of the same shape at regular intervals on its surface to prevent the drum from obstructing its function of sucking air and transporting the paper.

[0052] The lift detection unit 130 detects the lift of the sheet based on the extraction result of the feature amount extraction unit 110. The lift detection unit 130 may also detect the lift of the sheet in association with the position of the image area of ​​the sheet.

[0053] The feature extraction unit 110 includes a surface image extraction unit 112 that extracts an image of the surface region of the sheet from the scanned image of the sheet, and a noise removal unit 114 that removes noise regions from the image of the surface region of the sheet.

[0054] The feature extraction unit 110 also includes a gradation level detection unit 122 that detects a change in the gradation level of the image of the extracted surface area of ​​the sheet as a feature related to the lifting of the sheet.

[0055] The feature amount extracting unit 110 also includes an area discriminating unit 126 that discriminates a first area representing a hole from a second area other than the first area.

[0056] The gradation level detection unit 122 detects a change in gradation level in the main scanning or sub-scanning direction of the second region of the image determined by the region determination unit 126 .

[0057] The noise removal unit 114 may extract color information of the image, and remove noise areas in which a predetermined color is identified from the image of the surface area of ​​the sheet based on the extracted color information.

[0058] The noise removal unit 114 includes a periodicity calculation unit 116 that calculates the periodicity characteristics of the gradation levels according to the arrangement of a first region indicating a hole in the main scanning or sub-scanning direction and a second region other than that, and an area removal unit 118 that removes, as noise areas, areas from the image of the surface area of ​​the sheet that show characteristics different from the calculated periodicity of the gradation levels.

[0059] The floating detection unit 130 may determine whether the gradation level or the amount of change in gradation level detected by the gradation level detection unit 122 exceeds a predetermined value.

[0060] The floating detection unit 130 may determine whether the gradation level or the amount of change in gradation level detected by the gradation level detection unit 122 exceeds a predetermined value continuously in the main scanning or sub-scanning direction.

[0061] The feature amount extraction unit 110 includes an area calculation unit 120 that calculates the area of ​​the first region as a feature amount related to the lifting of the sheet.

[0062] The feature extraction unit 110 further includes a boundary region determination unit 124 that determines a boundary region between the first region and the second region, the boundary region indicating a cross section of the first region.

[0063] The area calculation section 120 may calculate the area of ​​the boundary region between the first region and the second region as the feature amount related to the lifting of the sheet.

[0064] The image forming unit 12 may stop the printing operation based on the detection result of the lift detection unit 130.

[0065] The combining unit 140 combines the lifted area detected by the lift detection unit 130 with the read image of the conveyance surface.

[0066] The RAM 103 may store a plurality of amounts of lift detected by the lift detection unit 130 in chronological order.

[0067] The prediction unit 170 predicts the time required to reach a predetermined amount of float based on the amount of float stored in the RAM 103.

[0068] The prediction notification unit 160 notifies the prediction unit 170 of the prediction result.

[0069] The prediction notification unit 160 may display the prediction result on the display unit 105 or may transmit the prediction result via the communication unit 104 to an external server connected to the communication unit 104 .

[0070] The result notification unit 150 notifies the detection result of the lift detection unit 130. The result notification unit 150 may display the detection result on the display unit 105 or may transmit the detection result via the communication unit 104 to an external server connected to the communication unit 104.

[0071] FIG. 5 is a diagram illustrating a sheet according to an embodiment. Referring to FIG. 5(A), sheet 27 is a heat transfer suppression sheet, i.e., a sheet with low thermal conductivity. Specifically, sheet 27 is made of a resin sheet such as a synthetic resin, more specifically a fluororesin sheet. Sheet 27 is attached to the drum surface of conveyor drum 20. Paper 15 is then conveyed onto sheet 27. Conveyor drum 20 adsorbs the paper using the suction force of air. For this reason, sheet 27 is characterized by having uniformly shaped holes at regular intervals to ensure adequate breathability. For example, sheet 27 may be made of a porous sheet or film formed in a lattice (mesh) pattern.

[0072] As shown in Figure 5(B), the outer peripheral surface 20a of the transport drum 20 is covered with a sheet 27, and the air suction holes 20b of the transport drum 20 are visible through this sheet 27 in a speckled pattern. Also, an enlarged view of a portion of the sheet 27 is shown on the right side of the figure.

[0073] FIG. 5(C) is a perspective view of the transport drum 20, in which the holes of the sheet 27, which are uniformly spaced and have the same shape, are enlarged.

[0074] FIG. 6 is a diagram illustrating the problem of the sheet 27 floating.

[0075] As shown in FIG. 6A, it can be seen that the sheet is floating in the area indicated by the arrow in the flat scanned image.

[0076] As shown in Fig. 6(B), this shows a case where the inkjet head comes into contact due to the sheet lift. Also, as shown in Fig. 6(C), not only does the inkjet head come into direct contact with the sheet due to the sheet lift, but the sheet lift can also cause the paper to lift, which can lead to contact between the paper and the inkjet head.

[0077] 7A and 7B are diagrams illustrating an outline of a method for detecting sheet lift according to an embodiment. As shown in Fig. 7A, a sensor detects the light reflected from the conveying drum surface at the hole in the sheet 27. Therefore, the detection value remains constant even when the sheet is lifted.

[0078] On the other hand, the surface of the sheet 27 reflects more light in response to the sheet floating, that is, the read gradation becomes brighter.

[0079] 7B, the waveform of the read gray scale changes as the sheet lift increases, and the sheet lift can be detected using this change as a feature.

[0080] 8 is a flow diagram illustrating a process for detecting floating of a sheet according to an embodiment. Referring to FIG. 8, image forming apparatus 10 executes an image acquisition process for acquiring a sheet image to be analyzed by image reading unit 24 (step S2).

[0081] Next, the image forming apparatus 10 performs preprocessing to convert the scanned image into one suitable for image processing (step S4). Next, the image forming apparatus 10 identifies an analysis target area from within the scanned image (step S6). Next, the image forming apparatus 10 identifies components that will become noise when detecting lifting from within the analysis target area, and identifies these as judgment exclusion areas (step S8). Next, the image forming apparatus 10 performs feature extraction processing (step S10). Next, the image forming apparatus 10 detects lifting from read gradation values ​​that change depending on the distance between the scanner surface and the sheet surface, which are acquired as feature amounts (step S12).

[0082] Next, the image forming apparatus 10 notifies the detection result (step S14).

[0083] Next, the image forming apparatus 10 executes print control based on the detection result (step S16). For example, if the image forming apparatus 10 is in the middle of printing, it executes control such as issuing a warning or stopping printing to prevent further damage to the apparatus based on the detection result of the floating. If the apparatus is stopped, it issues a warning before printing and controls whether to continue printing.

[0084] FIG. 9 is a flow diagram illustrating a subroutine process of the image acquisition process based on the embodiment. Referring to FIG. 9, the image reading unit 24 executes image reading settings (step ST2). The image reading unit 24 performs mode settings such as reading resolution. For example, various setting processes are performed to read the inline scanner sensor at a main scanning resolution of 560 dpi and a sub-scanning reading resolution of 300 dpi. Next, the image reading unit 24 specifies the acquisition target (step ST4). In this example, a configuration in which multiple sheets can be placed on the outer circumferential surface of the conveying drum 20 is described. Specifically, a configuration in which three sheets can be placed is described. In this case, a specification is received and set regarding which of the three sheets the image reading process is to be executed for. Note that it is also possible to specify that all three sheets be read as acquisition targets. Next, the image reading unit 24 executes a reading process to read the sheets on the conveying surface of the conveying drum 20 and saves the image data (step ST6). The image reading unit 24 saves the acquired image data in RAM 103. As for the timing of image acquisition, the image may be acquired according to a user instruction via the operation panel, or may be acquired automatically for the side of the paper that is not being transported during the printing operation.

[0085] Then, the image reading unit 24 ends the process (returns), and the process proceeds to step S4 in FIG.

[0086] FIG. 10 is a flow diagram illustrating a subroutine process of preprocessing based on an embodiment. Referring to FIG. 10, image adjustment unit 180 converts the image size obtained from image reading unit 24 to a size suitable for image processing (step ST8). For example, if the size of one side of a sheet is 775 mm x 575 mm, the image obtained using the settings of image reading unit 24 will be a large image equivalent to 480 MB. Therefore, it is considered necessary to convert the image to a size suitable for image processing, taking into account the various resources required for image processing (CPU, memory, etc.). This resolution conversion is performed using commonly known techniques, for example, to 1 / 2 or 1 / 4.

[0087] Next, the image adjustment unit 180 converts the image into one suitable for image processing by level conversion. Specifically, the image reading unit 24 has an optical system designed to read the surface of a sheet of paper placed on the conveying drum 20. However, when reading the surface of the paper, the distance to the sensor becomes greater and the amount of light reflected from the sheet is insufficient, resulting in a bias in the gradation values ​​of the input image. The image adjustment unit 180 performs gradation value correction processing to make these appropriate. Specifically, density conversion is performed using the following formula: Dt = Σ(i-128)×K1+128 i=0~255 Contrast adjustment Lv=dt+k2 k1: contrast coefficient k2: brightness value Then, the image adjustment unit 180 ends the process (returns), and the process proceeds to step S6 in FIG.

[0088] 11A and 11B are flowcharts illustrating a subroutine process for identifying a target area according to an embodiment of the present invention. Referring to Fig. 11A, the surface image extraction unit 112 acquires information on the reading size stored in the ROM 102, the RAM 103, or the like of the image forming apparatus 10 (step ST12).

[0089] Based on the reading size information, the surface image extraction unit 112 can identify the area to be analyzed from within the image area of ​​the image data obtained from the image reading unit 24. Specifically, since the image obtained from the image reading unit 24 includes the cylinder portion in addition to the sheet surface, only the area to be analyzed is identified.

[0090] The surface image extraction unit 112 trims the identified area (step ST14). Then, the analysis target image is stored. This process makes it possible to extract an image of the surface area of ​​the sheet from the scanned image data of the conveyance surface.

[0091] The surface image extraction unit 112 ends the process (returns), and the process proceeds to step S8 in FIG.

[0092] As shown in FIG. 11(B), an analysis target area (area framed by a solid line) within an image area (area framed by a dotted line) that was actually read is shown.

[0093] 12 is a flow diagram illustrating a subroutine process for identifying an exclusion area based on an embodiment. Referring to FIG. 12(A), the noise removal unit 114 executes a process for extracting a color stain area (step ST16). Specifically, the noise removal unit 114 extracts noise components due to ink adhesion on the sheet.

[0094] Next, the noise removal unit 114 executes a process of extracting black stain areas (step ST18).

[0095] Next, the noise removal unit 114 executes a process of extracting other exclusion regions (step ST20).

[0096] Then, the noise removal unit 114 ends the process (returns), and the process proceeds to step S10 in FIG.

[0097] As shown in FIG. 12B, the color space is converted from RGB to HSV, and thresholds are set for the hue, brightness, and saturation, and the corresponding color can be extracted by making a judgment.

[0098] For example, the hue, brightness, and saturation can be calculated using the following formulas.

[0099] H = 60* (GB) / (MAX MIN) +0 (MAX=R) = 60* (BR) / (MAX MIN) +120 (MAX=G) = 60* (RG) / (MAX MIN) +240 (MAX=B) S = (MAX-MIN) / MAX V = MAX Furthermore, the threshold values ​​for each color (primary color, secondary color) are set according to the following settings 1 to 6.

[0100] Setting 1: Y(60°±Th) Brightness: Th Saturation: Th Setting 2: M (300°±Th) Brightness Th Saturation: Th Setting 3:C(180°±Th) Brightness Th Saturation: Th Setting 4: R(0°±Th) Brightness: Th Saturation: Th Setting 5: G(120°±Th) Brightness Th Saturation: Th Setting 6:B(240°±Th) Brightness Th Saturation: Th FIG. 13 is a diagram illustrating the extraction process for noise removal based on the embodiment.

[0101] 13A shows the process of extracting black stain areas. The noise removal unit 114 extracts noise components caused by ink adhesion on the sheet. Specifically, the noise removal unit 114 can extract areas where periodicity is lost by the following method.

[0102] The periodicity calculation unit 116 calculates the periodicity characteristics of the gradation levels according to the arrangement of the first region indicating the holes in the main scanning direction (X direction) or the sub-scanning direction (Y direction) and the other second region (sheet surface portion). In a region without stains, a periodicity of the gradation levels with a constant cycle is observed in the region indicating the holes and the region indicating the sheet. On the other hand, in a region with stains, the periodicity of the gradation levels with a constant cycle is broken in the region indicating the holes and the region indicating the sheet.

[0103] The periodicity calculation unit 116 extracts an N×M pixel region (1). Next, the periodicity calculation unit 116 performs edge gradation removal processing (2). Next, the periodicity calculation unit 116 determines a sampling point N in the Y direction (3). Next, the periodicity calculation unit 116 determines a sampling point M in the X direction (4). Next, the periodicity calculation unit 116 calculates changes in gradation levels within the N×M pixel region (5). Next, the periodicity calculation unit 116 calculates the difference between the maximum value (MAX) and the minimum value (MIN) of the gradation levels (6). Next, the periodicity calculation unit 116 compares the calculated difference with a threshold value to determine whether the periodicity has been disrupted (7).

[0104] If the periodicity is broken, the N×M pixel region can be determined to be a black stain region.

[0105] FIG. 13(B) shows a case where a color stain area and a black stain area are extracted according to the above method.

[0106] The region removal unit 118 removes the region extracted as described above as a noise region.

[0107] Specifically, the region removal unit 118 removes the extracted color stain region and the extracted black stain region as noise regions. Furthermore, if there is another region to be excluded, such as the shape of the back surface of the sheet, the region removal unit 118 extracts the region based on predetermined region information and removes it as a noise region.

[0108] FIG. 14 is a flow diagram illustrating a subroutine process of a feature extraction process (part 1) according to an embodiment. Referring to FIG. 14(A), the region discrimination unit 126 executes region separation processing for the hole portions and the surface portion of the sheet 27 (step ST30). Specifically, the region discrimination unit 126 binarizes the gray-converted image before preprocessing (FIG. 14(B)) using a threshold value that can properly separate the hole portions and the surface portion (FIG. 14(C)). This removes minute noise components (FIG. 14(D)). Note that a median filter may be applied to the binarized image to remove the noise components.

[0109] Next, the area discrimination unit 126 executes a gradation substitution process (step ST32). Fig. 14(E) shows the image after the gradation substitution process. The gradation substitution calculates the average gradation of a certain area around the hole, which is also on the surface, and replaces the gradation of the hole with this value. This eliminates areas that are not related to the lifting, making it possible to minimize the impact on subsequent processing.

[0110] Next, the region discrimination unit 126 performs a smoothing process (step ST34). The smoothing process performs smoothing within a certain region to suppress local gradation fluctuations within the image that become noise components. For example, a Gaussian filter shown in FIG. 14(E) is used.

[0111] Next, the gradation level detection unit 122 executes a process of detecting a region where the gradation level changes (step ST36). The gradation level detection unit 122 detects a region where the gradation changes in the image that has been subjected to the smoothing process.

[0112] FIG. 15 is a diagram illustrating a change area of ​​the gradation level detected by the gradation level detection unit 122. In FIG.

[0113] Referring to FIG. 15(A), specifically, when compared with the average value in a certain range of the smoothed image, a region where a difference in gradation of a certain value or more occurs is held as a gradation change region.

[0114] Referring to FIG. 15(B), a method may be used in which the gradient amount (edge ​​change amount Δy / dΔx) of a certain point and another point at a certain distance apart is calculated, and if it is equal to or greater than a certain amount (>k), it is extracted as a gradation change area.

[0115] 15(C), gradation level detection unit 122 associates the extraction result of the gradation conversion region with the detected position and stores it. In this example, the region with a large gradation change is shown as a hatched region.

[0116] Then, the gradation level detection unit 122 ends the process (returns), and the process proceeds to step S12 in FIG.

[0117] 16 is a flow diagram illustrating a subroutine process of the feature extraction process (part 2) according to the embodiment. Referring to FIG. 16(A), the area discrimination unit 126 executes area separation processing for the hole portion and the surface portion of the sheet 27 (step ST40). Specifically, the area discrimination unit 126 executes processing for discriminating the areas of the hole portion and the surface portion using the same method as described in FIG. 14.

[0118] Next, the boundary area determination unit 124 extracts a boundary area (step ST42). Specifically, the boundary area determination unit 124 extracts a boundary area that indicates a cross section of the first area of ​​the surface portion between the first area that indicates the hole portion and the second area that indicates the surface portion.

[0119] Next, the area calculation unit 120 calculates the area of ​​the boundary region that indicates the cross-sectional portion (step ST44).

[0120] Then, the area calculation unit 120 ends the process (returns), and the process proceeds to step S12 in FIG.

[0121] 16(B) shows a case where the shape of the cross-sectional portion changes depending on whether the sheet is floating or not, and the area also changes. That is, the larger the floating of the sheet, the larger the area of ​​the cross-sectional portion.

[0122] FIG. 16(C) shows a boundary region indicating the extracted cross-sectional portion.

[0123] FIG. 16(D) shows the area value calculated by the area calculation unit 120, counting the number of ON dots in the boundary area. As an example, the sheet may be divided into N×M areas, and only the representative area within each area may be retained. The area value may be associated with the position on the image and retained. Note that the number of extraction results retained may be reduced by retaining a representative number within a certain division of the image area. In this example, areas with large area values ​​are shown as hatched areas.

[0124] 17 is a flow diagram illustrating a subroutine process of the feature extraction process (part 3) according to the embodiment. Referring to FIG. 17(A), the area discrimination unit 126 executes an area separation process for the hole portion and the surface portion of the sheet 27 (step ST50). Specifically, the area discrimination unit 126 executes a process for discriminating the areas of the hole portion and the surface portion using the same method as described in FIG. 14.

[0125] Next, the region determining unit 126 extracts the hole (step ST52). Specifically, the region determining unit 126 extracts a first region indicating the hole.

[0126] Next, the area calculation unit 120 calculates the area of ​​the hole (step ST54).

[0127] Then, the area calculation unit 120 ends the process (returns), and the process proceeds to step S12 in FIG.

[0128] 17(B) shows a case where the shape of the hole changes depending on whether the sheet is floating or not, and the area also changes. That is, the larger the floating of the sheet, the smaller the area of ​​the hole becomes.

[0129] FIG. 17(C) shows the extracted hole area.

[0130] FIG. 17(D) shows the area value calculated by the area calculation unit 120, counting the number of ON dots in the hole area. As an example, the sheet may be divided into N×M areas, and only the representative area within each area may be retained. The area value may be associated with the position on the image and retained. Note that the number of extraction results retained may be reduced by retaining a representative number within a certain division of the image area. In this example, areas with large area values ​​are shown as hatched areas.

[0131] Although the extraction process for three feature amounts has been described above, it is also possible to extract all of these feature amounts, extract only one of them, or extract feature amounts in any combination.

[0132] FIG. 18 is a flow diagram illustrating a subroutine process of the float detection process according to an embodiment. Referring to FIG. 18(A), float detection unit 130 executes a process of selecting an extraction result (step ST60). Specifically, FIGS. 18(B) to 18(D) show the extraction results extracted in the feature extraction process. The float detection unit 130 selects how to handle the extraction results of multiple feature amounts. For example, the process determines whether to validate one or multiple extraction results, and, in the case of multiple extraction results, whether to judge based on an OR condition, an AND condition, or a majority vote when a mismatch occurs between the detection results, based on settings stored in the device in advance.

[0133] Next, the lift detection unit 130 executes a lift determination process (step ST62).

[0134] Next, the lifting detection unit 130 executes a lifting ranking process (step ST64).

[0135] Then, the floating detection unit 130 holds the result (step ST66).

[0136] Then, the floating detection unit 130 ends the process (returns), and the process proceeds to step S14 in FIG.

[0137] Fig. 19 is a diagram illustrating the process of determining whether a mark is lifted. Fig. 19(A) and (B) show tables showing the relationship between gradation values ​​and the amount of lifted mark. Fig. 19(C) and (D) show tables showing the relationship between the area of ​​a boundary region and the amount of lifted mark. Fig. 19(E) and (F) show tables showing the relationship between the area of ​​a hole and the amount of lifted mark.

[0138] Figure 19(G) shows the extraction results showing the area values ​​of the boundary regions similar to those in Figure 18(C). Figure 19(H) shows the results of converting the area values ​​of the boundary regions into the amount of lift using Figures 19(C) and (D).

[0139] The hatched areas show areas where the amount of lift is large.

[0140] FIG. 20 is a diagram illustrating the ranking of float.

[0141] Fig. 20(A) shows the results of conversion into the amount of float described in Fig. 19(H). Fig. 20(B) shows a case where the amount of float is evaluated as being ranked A to C. Fig. 20(B) shows rank A, which indicates a large amount of float, and rank C, which indicates a small amount of float. As an example, the ranking results are shown where a float of 0.8 mm or more is rank A, less than 0.8 mm and 0.3 mm or more is rank B, and less than 0.3 mm is rank C.

[0142] The floating detection unit 130 stores the result as described above.

[0143] 21 is a flowchart illustrating a subroutine process of the notification process according to the embodiment. Referring to FIG. 21, result notification unit 150 acquires whether or not there is a float (step ST60).

[0144] Next, the result notifying unit 150 acquires the amount of floating (step ST62).

[0145] Next, the result notifying section 150 acquires the rank (step ST64).

[0146] Next, the result notification unit 150 displays and transmits the acquired information (step ST66).

[0147] The result notification unit 150 displays the presence or absence of lifting, the amount of lifting, and the rank on the display unit 105. Note that the presence or absence of lifting associated with the position on the sheet may also be displayed as the determination result. The result notification unit 150 may also transmit the information via the communication unit 104 to an external server that accumulates data.

[0148] Furthermore, the result notification unit 150 notifies the image forming unit 12 of the determination result.

[0149] Then, the process ends (returns), and the process proceeds to step S16 in FIG.

[0150] FIG. 22 is a flowchart illustrating a subroutine process of print control according to an embodiment.

[0151] 22, image forming unit 12 determines whether or not there is an abnormality notification (step ST70). Image forming unit 12 determines whether or not there is an abnormality notification from result notifying unit 150. Specifically, image forming unit 12 may determine that there is an abnormality notification when it determines that there is a float of rank A or B in the information received from result notifying unit 150 as the determination result.

[0152] When image forming unit 12 determines that there is an abnormality notification from result notifying unit 150 (YES in step ST70), it determines whether printing is in progress (step ST72).

[0153] In step ST72, if the image forming unit 12 determines that printing is not in progress (NO in step ST72), it displays a first warning (step ST74).

[0154] Then, the process ends (returns).

[0155] On the other hand, if the image forming unit 12 determines in step ST72 that the printing status is printing (YES in step ST72), it displays a second warning (step ST76). Next, the image forming unit 12 determines whether or not there is an instruction to stop printing (step ST78).

[0156] In step ST78, if the image forming unit 12 determines that there is an instruction to stop printing (stop in step ST78), it executes a stop operation (step ST80).

[0157] Then, the process ends (returns).

[0158] On the other hand, if the image forming unit 12 determines in step ST70 that there is no abnormality notification, it ends the process (returns). Specifically, the image forming unit 12 may determine that there is no abnormality notification if it determines that there is only a float of rank C in the information received from the result notifying unit 150 as the determination result.

[0159] 23 is a diagram illustrating a screen displaying the determination result of result notification unit 150 according to the embodiment. Referring to Fig. 23, in this example, three sheets are attached to the outer peripheral surface of conveyance drum 20. Specifically, they are displayed as cylinder A, cylinder B, and cylinder C.

[0160] Additionally, the location of the sheet lifting is indicated in the scanned image of the conveying surface. Specifically, the composition unit 140 generates a composite image by combining the lifting area detected by the lift detection unit 130 with the scanned image of the conveying surface, and the result notification unit 150 displays the composite image on the display unit 105. The result notification unit 150 displays the location of the lifting (bottom center (600, 700) (650, 960)), the amount of lifting (0.9 mm), and the lifting rank (Rank A). This display makes it possible to easily identify the location of the lifting as well as the occurrence of the lifting. This makes it easy to perform subsequent maintenance, sheet position adjustment, etc.

[0161] 24 is a diagram illustrating a case where a second warning according to an embodiment is displayed on display unit 105. Referring to FIG.

[0162] Specifically, the message "The sheet on cylinder A is floating. This may affect the head lifespan and image quality." is displayed. Also provided is a print stop button 202 that can be selected by the user. When the user selects the print stop button 202, the image forming unit 12 receives an instruction to stop printing. When the image forming unit 12 receives the instruction to stop printing, it executes a stop operation.

[0163] FIG. 25 is a diagram illustrating data relating to the amount of lift detected by lift detection unit 130 according to the embodiment.

[0164] 25 shows a case where the amount of lifting and the position where the lifting occurred are associated with each other in chronological order and stored in RAM 103. In this example, as an example, the case where data of records 1 to 9 are stored is shown.

[0165] The prediction unit 170 predicts the time required for the float to reach a predetermined amount of float based on the float data stored in the RAM 103.

[0166] FIG. 26 is a diagram illustrating prediction of the amount of lifting in prediction unit 170 according to the embodiment.

[0167] As shown in FIG. 26, an approximate curve showing the amount of float that changes over time is calculated based on the float data stored in the RAM 103.

[0168] In this example, an approximate curve is calculated using a quadratic polynomial based on data from nine floats. For example, y=0.0094x 2 A case is shown where a quadratic polynomial of -0.0409x+0.1683 is calculated.

[0169] In this example, a case where an approximate curve is obtained using a quadratic polynomial has been described, but this is not limiting and a cubic polynomial may also be used, and any method may be adopted as long as it is possible to obtain an approximate curve or an approximate straight line.

[0170] Based on the calculation result, the prediction unit 170 predicts that the amount of floating will reach 1 mm on the third day. Note that although the case where the amount of floating reaches 1 mm has been described in this example, the present invention is not limited to this and can be set to any value.

[0171] The prediction notification unit 160 can notify the user in advance that the amount of floating will reach 1 mm in three days. This notification makes it possible to easily carry out maintenance.

[0172] In this example, a configuration in which the prediction unit 170 and the prediction notification unit 160 are provided within the image forming apparatus 10 has been described as an example, but the present invention is not limited to this, and the image forming apparatus 10 may implement these functions in cooperation with an external server connected to a network. For example, float data stored in RAM 103 may be sent to the external server via communication unit 104, and the external server may execute the functions of the prediction unit 170 and the prediction notification unit 160, and the results from the external server may be received by communication unit 104 and displayed on the display unit 105 of the image forming apparatus 10. The prediction is not limited to a display, but may be an audio notification, or any other means capable of notifying the user may be used.

[0173] Furthermore, the external server may be configured to have the functions of either the prediction unit 170 or the prediction notification unit 160. Furthermore, the external server may be configured to have functions other than these functions.

[0174] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0175] 10 Image forming apparatus, 100 Control unit, 102 ROM, 103 RAM, 104 Communication unit, 105 Display unit, 110 Feature extraction unit, 112 Surface image extraction unit, 114 Noise removal unit, 116 Periodicity calculation unit, 118 Area removal unit, 120 Area calculation unit, 122 Gradation level detection unit, 124 Boundary area discrimination unit, 126 Area discrimination unit, 130 Floating detection unit, 140 Combining unit, 150 Result notification unit, 160 Prediction notification unit, 170 Prediction unit, 180 Image adjustment unit.

Claims

1. a paper transport mechanism having a sheet having a plurality of holes mounted on a transport surface; an image reading unit that reads the sheet on the conveying surface of the paper conveying mechanism and outputs a read image; a feature extraction unit that extracts a feature related to the floating of the sheet from the read image of the sheet; and a lifting detection unit that detects lifting of the sheet based on the extraction result.

2. The feature extraction unit a surface image extraction unit that extracts an image of a surface area of ​​the sheet from the read image of the conveyance surface; 2. The image forming apparatus according to claim 1, further comprising a noise removal section for removing noise areas from the image of the surface area of ​​the sheet.

3. 3. The image forming apparatus according to claim 2, wherein the feature extraction section includes a gradation level detection section that detects a change in gradation level of the extracted image of the surface area of ​​the sheet as a feature related to the lifting of the sheet.

4. the feature extraction unit includes a region discrimination unit that discriminates a first region representing the hole from the image and a second region other than the first region; 4. The image forming apparatus according to claim 3, wherein the gradation level detection section detects a change in gradation level in the main scanning or sub-scanning direction of the second region of the image.

5. The noise removal unit extracting color information from the image; 3. The image forming apparatus according to claim 2, further comprising: a step of removing a noise area in which a predetermined color is identified from the image of the surface area of ​​the sheet based on the extracted color information.

6. The noise removal unit a periodicity calculation unit that calculates a periodicity characteristic of gradation levels according to an arrangement of a first region indicating the hole and a second region other than the first region in a main scanning or sub-scanning direction; 3. The image forming apparatus according to claim 2, further comprising a region removing section that removes, as a noise region, a region that exhibits characteristics different from the calculated periodicity of the gradation levels from the image of the surface region of the sheet.

7. 4. The image forming apparatus according to claim 3, wherein said lift detection section determines whether or not the gradation level or the amount of change in gradation level detected by said gradation level detection section exceeds a predetermined value.

8. 8. The image forming apparatus according to claim 7, wherein said lift detection section determines whether the gradation level or the amount of change in gradation level detected by said gradation level detection section exceeds a predetermined value continuously in the main scanning or sub-scanning direction.

9. The feature extraction unit an area discrimination unit that discriminates a first area representing the hole from the image and a second area other than the first area; 3. The image forming apparatus according to claim 2, further comprising an area calculation unit that calculates the area of ​​the first region as a feature amount related to the floating of the sheet.

10. the feature extraction unit further includes a boundary region determination unit that determines a boundary region between the first region and the second region, the boundary region indicating a cross-sectional portion of the first region; The image forming apparatus according to claim 9 , wherein the area calculation section calculates an area of ​​a boundary area between the first area and the second area as the feature amount related to the lifting of the sheet.

11. further comprising an image forming unit that performs a printing operation; 11. The image forming apparatus according to claim 1, wherein the image forming unit stops the printing operation based on the detection result of the lift detection unit.

12. 12. The image forming apparatus according to claim 1, further comprising a combining unit that combines the lifted area detected by the lift detection unit with the read image of the transport surface.

13. a storage unit that stores, in chronological order, a plurality of amounts of lift detected by the lift detection unit; 13. The image forming apparatus according to claim 1, further comprising: a prediction unit that predicts a time required for a predetermined amount of float to be reached based on the amount of float stored in the memory unit.

14. The image forming apparatus according to claim 13 , further comprising a prediction notification unit that notifies the prediction result of the prediction unit.

15. The image forming apparatus according to claim 14 , wherein the prediction notification unit displays the prediction result on a display unit or transmits the prediction result to an external server connected to a communication unit via the communication unit.

16. 16. The image forming apparatus according to claim 1, further comprising a result notification unit that notifies a result of detection by said lift detection unit.

17. 17. The image forming apparatus according to claim 16, wherein the result notification unit displays the detection result on a display unit or transmits the detection result to an external server connected to a communication unit via the communication unit.

18. 18. The image forming apparatus according to claim 1, wherein the lifting detection unit detects the lifting of the sheet in association with a position on the sheet.

19. 19. The image forming apparatus according to claim 1, wherein the image reading section reads the sheet and outputs a planar read image.

20. 20. The image forming apparatus according to claim 1, wherein the paper transport mechanism transports the paper by sucking air through the plurality of holes.

21. 1. A control method for an image forming apparatus having a paper transport mechanism on a transport surface of which a sheet having a plurality of holes is attached, comprising: reading the sheet on the conveying surface of the paper conveying mechanism and outputting a read image; extracting a feature amount related to the floating of the sheet from the read image of the sheet; and detecting floating of the sheet based on the extraction result.

22. A control program for an image forming apparatus having a paper transport mechanism on a transport surface of which a sheet having a plurality of holes is mounted, The computer of the image forming apparatus executes the control program. a step of reading the sheet on the conveying surface of the paper conveying mechanism and outputting a read image; Pu and, extracting a feature amount related to the floating of the sheet from the read image of the sheet; and detecting floating of the sheet based on the extraction result.

Images