Image forming apparatus

Abstract

The present application relates to an image forming apparatus, and reduces the possibility of occurrence of fixing failure. An image forming apparatus of an embodiment includes a heating section, a pressing section, a detecting section, a control section, and a setting section. The heating section heats in order to heat paper conveyed in a conveying direction over an entire area in a direction orthogonal to the conveying direction. The pressing section applies pressure to the paper heated by the heating section over the entire area in the direction orthogonal to the conveying direction. The detecting section detects a temperature of the pressing section. The control section controls the heating section so that the temperature detected by the detecting section approaches a control temperature. The setting section sets one of a plurality of candidate temperatures, which are different from each other, as the control temperature, based on the number of image formations in a task and a paper size used, before an image formation related to the task is started.

Description

Technical Field

[0001] Embodiments of the present invention relate to an image forming apparatus. Background Technology

[0002] For example, in an image forming apparatus for electronic photography, a heated roller is used for fixing the developer attached to the paper.

[0003] When the pressure applied to the paper and developer by the roller is reduced, poor fixing may occur.

[0004] Given this situation, it is desirable to reduce the likelihood of poor fixing. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide an image forming apparatus that can reduce the possibility of poor fixing.

[0006] The image forming apparatus of this embodiment includes a heating unit, a pressing unit, a detection unit, a control unit, and a setting unit. The heating unit heats the paper being transported in the transport direction over an entire area in a direction orthogonal to the transport direction. The pressing unit applies pressure to the paper heated by the heating unit over the entire area in a direction orthogonal to the transport direction. The detection unit detects the temperature of the pressing unit. The control unit controls the heating unit to bring the temperature detected by the detection unit close to a control temperature. Before image forming related to a task begins, the setting unit sets one of several candidate temperatures as the control temperature based on the number of images to be formed in that task and the size of the paper used. Attached Figure Description

[0007] Figure 1 This is a diagram that briefly illustrates the mechanical structure of an MFP according to one embodiment.

[0008] Figure 2 It is a brief illustration of the relationship with Figure 1 The diagram shows the control-related components of an MFP.

[0009] Figure 3 It is shown Figure 2 The diagram shows the block diagram of the main circuitry of the system controller.

[0010] Figure 4 It is by Figure 3 The flowchart shown illustrates the printing control process performed by the processor.

[0011] Figure 5 This indicates multiple position pairs along the long side of the fixing belt. Figure 1 The graph shows the results of temperature measurements on the fixing belt.

[0012] Figure 6 This indicates multiple positions along the long side of the pressure roller. Figure 1 The graph shows the results of temperature measurements taken on the pressure roller.

[0013] Figure 7 This indicates multiple position pairs along the long side of the fixing belt. Figure 1 The graph shows the results of temperature measurements on the fixing belt.

[0014] Figure 8 This indicates multiple positions along the long side of the pressure roller. Figure 1 The graph shows the results of temperature measurements taken on the pressure roller.

[0015] Figure 9 This indicates the control of temperature and printing speed, and... Figure 1 The diagram shows the relationship between the temperature difference corresponding to the position of the pressure roller along its long side.

[0016] Figure 10 It means and Figure 1 The diagram shows the relationship between the temperature difference and the outer diameter difference corresponding to the position of the pressure roller along its long side.

[0017] Figure 11 It is a graph showing the relationship between temperature control, printing speed, and offset level.

[0018] Explanation of reference numerals in the attached figures

[0019] 1…Paper feed unit, 2…Printing motor, 3…Fixing unit, 4…ADU, 5…Paper tray, 6…Motor assembly, 7…Sensor assembly, 10-1~10-3…Paper tray, 11-1~11-3…Pick-up roller, 12-1~12-3…Transfer roller, 13…Transfer roller, 14…Alignment roller, 20…Belt, 21~23…Support roller, 24-1~24-4…Image forming unit, 25…Exposure unit, 26…Transfer roller, 30…Fixing belt, 31…Pressing pad, 32…Heater, 33…Fusing belt Pressure roller, 34… Peeling plate, 35… Temperature sensor, 81… Printing controller, 82… Forming controller, 83… Exposure controller, 84… Transfer controller, 85… Fixing controller, 86… Reversal controller, 87… Motor controller, 101… Scanner, 102… Printer, 103… Communication unit, 104… System controller, 105… Operation panel, 1041… Processor, 1042… Main memory, 1043… Auxiliary storage unit, 1044… Interface unit, 1045… Transmission path. Detailed Implementation

[0020] The embodiments will now be described using the accompanying drawings. It should be noted that the following embodiments are described using an MFP (multi-function peripheral) comprising an image forming apparatus as an example. The various actions and processes described below are merely examples; the order of some actions and processes can be changed, some actions and processes can be omitted, or other actions and processes can be added, etc., as appropriate.

[0021] First, the configuration of the MFP involved in this embodiment will be explained.

[0022] Figure 1 This is a diagram that briefly illustrates the mechanical structure of the MFP100 according to the embodiment.

[0023] like Figure 1 As shown, the MFP100 has a scanner 101 and a printer 102.

[0024] After reading the image of the original document, scanner 101 generates image data corresponding to the original document. Scanner 101 uses an image sensor, such as a CCD (charge-coupled device) line sensor, to generate image data corresponding to the reflected light image from the reading surface of the original document. Scanner 101 scans an original document placed on a document stage using an image sensor that moves along the original document. Alternatively, scanner 101 scans an original document fed by an ADF (auto document feeder) using a fixed image sensor.

[0025] Printer 102 forms an image electronically on a medium on which the image is to be formed. A typical medium is printing paper, such as cut paper. Therefore, printing paper will be used as the medium in the following description. However, paper sheet materials other than cut paper can also be used as the medium, as well as sheet materials made from raw materials such as resin other than paper. Printer 102 has a color printing function for printing color images onto printing paper and a monochrome printing function for printing monochrome images onto printing paper. Printer 102 forms a color image by, for example, superimposing an element image using, a developer that uses three colors—yellow, magenta, and cyan—or four colors obtained by adding black to these. Alternatively, printer 102 forms a monochrome image, for example, using a black developer. The developer is, for example, a toner. The developer may also include, for example, a toner and a carrier. However, printer 102 may only have either a color printing function or a monochrome printing function.

[0026] exist Figure 1In the example configuration shown, printer 102 includes a paper feeding unit 1, a printing motor 2, a fixing unit 3, an ADU (automatic double-sided unit) 4, and a paper discharge tray 5.

[0027] The paper feeding unit 1 includes paper feeding boxes 10-1, 10-2, 10-3, pickup rollers 11-1, 11-2, 11-3, conveying rollers 12-1, 12-2, 12-3, conveying roller 13, and alignment roller 14.

[0028] Paper feed trays 10-1, 10-2, and 10-3 store stacked printed papers. The printed papers stored in paper feed trays 10-1, 10-2, and 10-3 can be different types of printed papers of different sizes and materials, or they can be the same type of printed paper. Paper feed unit 1 may also include a manual tray.

[0029] Pick-up rollers 11-1, 11-2, and 11-3 take out the printing paper one by one from each paper feed box 10-1, 10-2, and 10-3. Pick-up rollers 11-1, 11-2, and 11-3 feed the taken-out printing paper into the conveyor rollers 12-1, 12-2, and 12-3.

[0030] The conveyor rollers 12-1, 12-2, and 12-3 feed the printing paper fed from the pickup rollers 11-1, 11-2, and 11-3 to the conveyor roller 13 via a conveying path (formed by guide members, etc., not shown).

[0031] The conveyor roller 13 further conveys the printing paper fed from any one of the conveyor rollers 12-1, 12-2, and 12-3 to the alignment roller 14.

[0032] The alignment roller 14 corrects the tilt of the printing paper. The alignment roller 14 adjusts the timing of feeding the printing paper to the printing engine 2.

[0033] The number of paper feed trays, pickup rollers, and conveyor rollers is not limited to three sets; any number of sets can be configured. Additionally, if a manual tray is installed, even one set of paper feed trays and their paired pickup and conveyor rollers may not be required.

[0034] The printing engine 2 includes a belt 20, support rollers 21, 22, 23, image forming units 24-1, 24-2, 24-3, 24-4, an exposure unit 25, and a transfer roller 26.

[0035] The band 20 is in a loop to maintain Figure 1 The belt 20 is supported by support rollers 21, 22, and 23 as shown. The belt 20 moves towards the support rollers 21 as they rotate. Figure 1The belt 20 rotates counterclockwise. The outer surface of the belt 20 (hereinafter referred to as the image-carrying surface) temporarily carries the image to be formed on the printing paper by the developer. From the viewpoint of heat resistance and abrasion resistance, the belt 20 uses, for example, semi-conductive polyimide. Sub-scanning can be achieved by the movement of the image-carrying surface that occurs as the belt 20 rotates; the direction of movement of the image-carrying surface is also referred to as the sub-scanning direction.

[0036] Image forming units 24-1 to 24-4 each include a photoreceptor, a belt capacitor, a developer, a transfer roller, and a cleaner, and possess a known structure for forming an image based on an electrophotographic method in cooperation with the exposure unit 25. Image forming units 24-1 to 24-4 are arranged along the belt 20 with the axes of their respective photoreceptors parallel to each other. The image forming units 24-1 to 24-4 differ only in the color of the developer used; their structure and operation are identical. Image forming unit 24-1, for example, uses a black developer to form an element image. Image forming unit 24-2, for example, uses a cyan developer to form an element image. Image forming unit 24-3, for example, uses a magenta developer to form an element image. Image forming unit 24-4, for example, uses a yellow developer to form an element image. Image forming units 24-1 to 24-4 overlap the element images of each color on the image-bearing surface of the belt 20. Thus, at the point in time when the image forming unit 24-1 has passed, the image forming units 24-1 to 24-4 form a color image on the image carrier surface of the band 20, in which the images of each element of each color overlap. It should be noted that, although the illustration is omitted, the developer container holding the developer of each color is, for example, disposed in the information space of the band 20.

[0037] Exposure unit 25 exposes the photoreceptors of image forming units 24-1 to 24-4 according to image data representing element images of each color. Exposure unit 25 can be a laser scanner or an LED (light emitting diode) head, etc. If a laser scanner is used, exposure unit 25 includes, for example, a semiconductor laser element, a multi-faceted mirror, an imaging lens system, and a mirror. In this case, exposure unit 25 selectively incident a laser beam emitted from the semiconductor laser element according to the image data onto the photoreceptors of image forming units 24-1 to 24-4 by switching the emission direction through the mirror. Furthermore, exposure unit 25 directs the laser beam along the axis of the photoreceptor through the multi-faceted mirror. Figure 1 The laser beam scans along the depth direction (in the image). This scanning is called the main scan, and its direction is called the main scan direction.

[0038] The transfer roller 26 is arranged parallel to the support roller 23, with the belt 20 sandwiched between them. The transfer roller 26 sandwiches the printing paper fed from the registration roller 14 between it and the image-carrying surface of the belt 20. Then, the transfer roller 26 uses electrostatic force to transfer the image formed by the developer on the image-carrying surface of the belt 20 onto the printing paper. That is, the support roller 23 and the transfer roller 26 constitute the transfer section. Sometimes, developer remains on the image-carrying surface of the belt 20 without being completely transferred to the printing paper. Therefore, the developer adhering to the image-carrying surface of the belt 20 after passing between the support roller 23 and the transfer roller 26 is removed by a cleaner (not shown) before reaching the image forming unit 24-4.

[0039] Therefore, the printing engine 2 forms an image of the printing paper fed by the alignment roller 14 using an electronic photographic method.

[0040] The fixing unit 3 fixes the developer onto the printing paper by melting the developer adhering to it while pressing it against the paper being delivered from the printing engine 2. The fixing unit 3 includes a fixing belt 30, a pressing pad 31, a heater 32, a pressure roller 33, a peeling plate 34, and a temperature sensor 35. It should be noted that a cross-section of the fixing belt 30 and the pressure roller 33 perpendicular to the axis of rotation is shown.

[0041] The fixing tape 30 is, for example, a ring-shaped tape comprising a heat-resistant resin. The fixing tape 30 is wound around... Figure 1 The rotating axis extending in the depth direction is supported by a support mechanism (not shown). The length of the fixing belt 30 in the rotation axis direction is proportional to its length in the paper transport direction ( Figure 1 (up and down direction) orthogonal direction ( Figure 1 The maximum value of the length (hereinafter referred to as width) of the printing paper in the depth direction is large. The outer diameter of the fuser belt 30 is typically smaller than its length in the rotation axis direction. Therefore, the rotation axis direction is the direction of the long side of the fuser belt 30. The fuser belt 30 heats the printing paper and the developer attached to the printing paper by being heated by the heater 32.

[0042] The pressing pad 31 is configured to contact the inner side of the fixing belt 30, pressing the fixing belt 30 onto the pressure roller 33.

[0043] Heater 32 heats the fuser belt 30. Heater 32 is, for example, an IH (induction heating) heater, but any other type of heater can be used appropriately. Heater 32 may have only one heating element or multiple heating elements arranged in the direction of rotation axis. Therefore, heater 32 heats the printing paper across the fuser belt 30, and is an example of a heating element.

[0044] The pressure roller 33 is arranged parallel to the fixing belt 30. The pressure roller 33 is positioned around the fixing belt. Figure 1 The rotating axis extending in the depth direction is supported by a support mechanism (not shown). The length of the pressure roller 33 in the direction of its rotation axis is greater than the maximum width of the printing paper. The outer diameter of the pressure roller 33 is typically smaller than its length in the direction of its rotation axis. Therefore, the direction of its rotation axis is the direction of the long side of the pressure roller 33. The pressure roller 33 feeds the printing paper, which is fed from the printing engine 2, between itself and the fixing belt 30, and feeds the printing paper and the fixing belt 30 together toward the ADU4. Therefore, the pressure roller 33 presses the printing paper while clamping the printing paper and the fixing belt 30 together between itself and the pressing pad 31. That is, the function of the pressing part is realized by the cooperation of the fixing belt 30, the pressing pad 31, and the pressure roller 33. It should be noted that the pressure roller 33 is also part of the function of heating the developer adhering to the printing paper by being heated by the heat of the fixing belt 30.

[0045] However, the function of the fixing unit is not limited to the above-described configuration; any structure capable of pressing the printing paper can be used, and therefore any structure is acceptable. For example, a general roller can be used instead of the fixing belt 30 and the pressing pad 31, and the function of the pressing unit can be achieved by pressing at least one of the roller and the pressure roller 33 against the other roller. Alternatively, the pressure roller 3 can be replaced with the same structure as the fixing belt 30 and the pressing pad 31 to achieve the function of the pressing unit. Furthermore, for example, the function of the pressing unit can be achieved by setting a structure between the rollers and the fixing plate that allow the printing paper to pass through each other, thereby having the roller and the fixing plate function as the pressing unit.

[0046] Heating the printing paper can also be achieved using various other methods instead of heating the fuser belt 30 and pressure roller 33. For example, instead of heater 32, a heater or a heater other than heater 32 can be provided to directly heat the pressure roller 33. Alternatively, for example, instead of heater 32, a heater or a heater other than heater 32 can be provided to directly heat the printing paper before it is clamped by the fuser belt 30 and pressure roller 33. In these cases, the heater provided instead of heater 32 or the heater other than heater 32 also functions as a heating element.

[0047] The peeling plate 34 peels the printed paper that has passed between the fuser belt 30 and the pressure roller 33 from the fuser belt 30, preventing the printed paper from being rolled into the fuser belt 30.

[0048] Temperature sensor 35 measures the temperature of the fixing belt 30. Typically, temperature sensor 35 is configured to measure the temperature near the center of the fixing belt 30 along its long side. Temperature sensor 35 is an example of a detection unit. However, temperature sensor 35 can be arbitrarily configured as long as it can measure the temperature of the fixing belt 30. Temperature sensor 35 can also be configured to measure the temperature of heater 32, pressure roller 33, or the temperature around the fixing belt or pressure roller 33. In other words, the detection unit can achieve indirect detection in addition to directly detecting the temperature of the pressing part.

[0049] ADU4 includes multiple rollers and selectively performs the following two actions. The first action is to feed the printed paper, which has passed through the fixing unit 3, directly to the paper output tray 5. This first action is performed after single-sided or double-sided printing has ended. The second action is to turn the printed paper, after temporarily conveying it to the paper output tray 5, and feed it towards the printing engine 2. This second action is performed after only one side of the image has been formed in double-sided printing.

[0050] Paper tray 5 receives the printed paper that is ejected after the image has been formed.

[0051] Figure 2 This is a block diagram that briefly illustrates the configuration related to the control of the MFP100. It should be noted that... Figure 2 In the middle, to and Figure 1 The same component shown is labeled with the same reference numeral, and its detailed description is omitted.

[0052] In addition to the scanner 101 and printer 102, the MFP100 also includes a communication unit 103, a system controller 104, and an operation panel 105.

[0053] The communication unit 103 performs processing for communication with information terminals such as computer devices and image terminals such as fax devices via communication networks such as LAN (local area network) and public communication networks.

[0054] The system controller 104 uniformly controls the various parts constituting the MFP100 in order to realize the desired actions of the MFP100. It should be noted that the desired actions of the MFP100 are, for example, actions to realize various functions that can be achieved by existing MFPs.

[0055] The operation panel 105 includes an input device and a display device. The operation panel 105 receives operator instructions via the input device. The operation panel 105 displays various information in response to operator notifications via the display device. For example, a touch panel can be used as the operation panel 105.

[0056] The aforementioned fixing unit 3, ADU4, image forming units 24-1 to 24-4, exposure unit 25, and transfer roller 26 of printer 102 are elements controlled by the printer. In addition to these elements, printer 102 also includes a motor assembly 6 as an element controlled by the printer. Motor assembly 6 includes at least one of the pickup rollers 11-1, 11-2, 11-3, transport rollers 12-1, 12-2, 12-3, transport roller 13, registration roller 14, support roller 21, transfer roller 26, fixing belt 30, and pressure roller 33, and also includes multiple motors for rotating the rollers included in ADU4.

[0057] The printer 102 also includes a sensor group 7, a print controller 81, a forming controller 82, an exposure controller 83, a transfer controller 84, a fixing controller 85, a reversal controller 86, and a motor controller 87.

[0058] Sensor group 7 includes various sensors used to monitor the operational status of the device.

[0059] In order to achieve the desired actions of the printer 102 under the control of the system controller 104, the print controller 81 uniformly controls the various parts constituting the printer 102.

[0060] The image forming controller 82, exposure controller 83, transfer controller 84, fixing controller 85, reversal controller 86, and motor controller 87 all operate under the control of the printing controller 81. They respectively control the operation of the image forming units 24-1 to 24-4, the exposure unit 25, the transfer roller 26, the ADU4, and the motor assembly 6. It should be noted that the fixing controller 85 has the following function: by adjusting the drive power supplied to the heater 32, it controls the heating of the heater 32 so that the temperature measured by the temperature sensor 35 is close to the control temperature. However, the fixing controller 85 controls the entire heater 32 as a whole. That is, the fixing controller 85 does not have the function of individually controlling the temperature of the heater 32 in each of the multiple regions along the long side of the fixing belt 30. In other words, the fixing controller 85 functions as a control unit.

[0061] Figure 3 This is a block diagram showing the main circuitry of the system controller 104.

[0062] The system controller 104 includes a processor 1041, a main memory 1042, an auxiliary storage unit 1043, an interface unit 1044, and a transmission path 1045.

[0063] The processor 1041, main memory 1042, and auxiliary storage unit 1043 are connected by a transmission path 1045 to form a computer for performing information processing for the aforementioned control.

[0064] Processor 1041 is equivalent to the central part of the aforementioned computer. Processor 1041 performs the information processing described later according to information processing programs such as the operating system, middleware, and application programs.

[0065] Main memory 1042 corresponds to the main storage portion of the computer described above. Main memory 1042 includes non-volatile storage areas and volatile storage areas. Main memory 1042 stores information processing programs in the non-volatile storage areas. In addition, main memory 1042 sometimes also stores data required by processor 1041 to perform processing for controlling various parts in both non-volatile and volatile storage areas. Main memory 1042 uses the volatile storage areas as working areas for processor 1041 to appropriately rewrite data.

[0066] The auxiliary storage unit 1043 corresponds to the auxiliary storage section of the aforementioned computer. As the auxiliary storage unit 1043, known storage devices such as EEPROM (electrically erasable programmable read-only memory), HDD (hard disk drive), and SSD (solid-state drive) can be used individually or in combination. The auxiliary storage unit 1043 stores data used by the processor 1041 during various processes, and data generated by the processes performed by the processor 1041. The auxiliary storage unit 1043 stores information processing programs.

[0067] Interface unit 1044 performs known processing for sending and receiving data between scanner 101, printer 102, communication unit 103, system controller 104, and operation panel 105. As interface unit 1044, known interface devices or communication devices can be used individually or in combination.

[0068] The transmission path 1045 includes an address bus, a data bus, and control signal lines, which transmit and receive data and control signals between the connected parts.

[0069] Next, the operation of the MFP100 configured as shown above will be explained. It should be noted that the following explanation focuses on the operations that are different from those of other existing MFPs, and the explanation of other operations will be omitted.

[0070] When a task such as copying accompanying printing by printer 102 is requested, the processor 1041 in system controller 104 executes information processing (hereinafter referred to as print control processing) for controlling printer 102 according to the application program. It should be noted that the task requested here will be referred to as an object task.

[0071] Figure 4 This is a flowchart of the printing control process performed by processor 1041.

[0072] As ACT1, processor 1041 imports print data. If the task is, for example, photocopying, processor 1041 causes scanner 101 to read the original and imports the generated print data from scanner 101. Alternatively, if the task is, for example, network printing or fax reception, processor 1041 causes communication unit 103 to receive the print data. It should be noted that processor 1041 acquires all print data to be printed within the task.

[0073] As ACT2, processor 1041 determines the type of printing paper to be used. For example, if automatic paper selection is specified, processor 1041 determines the size of the original document represented by the print data obtained in ACT1, and sets the printing paper suitable for printing the original document of that size as the type of printing paper to be used. If the operation of specifying the type of printing paper is performed by an operator, for example, using the operation panel 105, processor 1041 sets the specified printing paper as the type of printing paper to be used.

[0074] As ACT3, processor 1041 confirms whether the printing paper used is a pre-defined narrow-width paper. It should be noted that, for example, the designer of the MFP100 can arbitrarily specify which size of printing paper is designated as narrow-width paper. Narrow-width paper is defined as printing paper where the temperature difference between the area of ​​the printing paper in contact with the pressure roller 33 (hereinafter referred to as the contact area) and the area of ​​the printing paper not in contact with the pressure roller 33 (hereinafter referred to as the non-contact area) is large, resulting in poor fixing due to the difference in the outer diameter of the pressure roller 33.

[0075] Here, the fixing defects caused by the difference in the outer diameter of the pressure roller 33 will be explained.

[0076] Figure 5 This is a graph showing the results of temperature measurements of the fixing belt 30 at multiple locations along its long side. Figure 6 This is a graph showing the results of temperature measurements of the pressure roller 33 at multiple locations along its long side. It should be noted that these... Figure 5 and Figure 6 This indicates the temperature measurement result during printing in the same task.

[0077] Figure 5 and Figure 6 The dashed curves represent the measurement results when the leading edge of the first sheet of printing paper passes between the fixing belt 30 and the pressure roller 33. Additionally, Figure 5 and Figure 6 The solid lines represent the measurement results when the leading edge of the 50th sheet of printing paper passes between the fuser belt 30 and the pressure roller 33. The width of the printing paper used is approximately half the length of the long side of the fuser belt 30 and the pressure roller 33. The printing speed and temperature control are both preset to standard values ​​(hereinafter referred to as standard speed) and standard temperature.

[0078] according to Figure 5 and Figure 6 It can be seen that as the number of consecutive printed sheets increases, the temperature of the central portion of both the fixing belt 30 and the pressure roller 33 decreases. This is because heat is lost due to the contact with the printing paper.

[0079] Furthermore, the outer diameter of the pressure roller 33 changes due to thermal expansion, resulting in a smaller outer diameter at the center of the long side compared to the ends of the long side. This causes a decrease in the pressing pressure of the central portion of the pressure roller 33 on the fixing belt 30, potentially leading to poor fixing at the center of the pressure roller 33.

[0080] For the reasons mentioned above, the narrower the width of the printing paper, the more likely this fixing defect will occur. Therefore, for example, the designers of the MFP100, based on experiments, simulations, or experience, have specified paper sizes where fixing defects are problematic as narrow-width paper. As an example, assume that A5 and ST-R size printing papers with a width of 150mm or less are specified as narrow-width paper.

[0081] If the printing paper used is suitable for narrow width paper, then processor 1041 in Figure 4 If the condition is "yes" in ACT3, proceed to ACT4.

[0082] As ACT4, processor 1041 determines the total number of printouts in the target task. For example, processor 1041 determines the total number of printouts by checking the number of pages of the original document represented by the print data imported in ACT1 and multiplying the number of print copies contained in the print data, or another specified number of print copies, by the aforementioned number of pages.

[0083] As ACT5, processor 1041 confirms whether printing the total number of sheets determined in ACT4 meets the predefined criteria for mass printing. For example, processor 1041 considers the relationship between the number of printed sheets and the occurrence of transfer defects, and determines that mass printing is met when the number of printed sheets exceeds a predefined threshold. It should be noted that, for example, the designer of the MFP100 can appropriately determine which situation constitutes mass printing, or which specific process is used, based on experiments, simulations, or experience. For example, the aforementioned threshold can be varied depending on the size of the printing paper used.

[0084] If the print volume is not met, processor 1041 determines "No" in ACT5 and proceeds to ACT6. If the paper used is not narrow-width paper, processor 1041 determines "No" in ACT3 and proceeds to ACT6. In other words, processor 1041 proceeds to ACT6 if the paper used is not narrow-width paper or if the print volume is not met.

[0085] As ACT6, processor 1041 instructs print controller 81 to begin printing based on print data imported in ACT1. Print controller 81 operates its components according to instructions from system controller 104 to print the original document represented by the print data onto printing paper. This operation can be, for example, the same as that performed by other printers of the same type. Specifically, print controller 81 instructs fuser controller 85 to set the control temperature of fuser unit 3 to a standard temperature. Additionally, print controller 81 instructs forming controller 82, exposure controller 83, reversal controller 86, and motor controller 87 to set the printing speed to a predetermined standard speed. It should be noted that, typically, standard temperatures are specified separately for monochrome and color printing, with the standard temperature for color printing being higher than that for monochrome printing. Furthermore, different standard temperatures may be specified for slow-speed printing or when using thick paper, etc.

[0086] As ACT7, processor 1041 waits for the completion of printing indicated in ACT6. Then, if processor 1041 is notified of printing completion from print controller 81, it determines "yes" and ends the print control process.

[0087] On the other hand, if the processor 1041 is using narrow-width paper and is in a situation of large-volume printing, it determines "yes" in ACT5 and proceeds to ACT8.

[0088] As ACT8, processor 1041 instructs print controller 81 to change settings related to control temperature and print speed. For example, processor 1041 instructs print controller 81 to change the control temperature to an increased temperature, which is specified to be higher than the standard temperature. Additionally, processor 1041 instructs print controller 81 to change the print speed to a decreased speed, which is specified to be lower than the standard speed. For example, the designer of MFP100 can appropriately specify the increased temperature and decreased speed based on experiments, simulations, or experience. It should be noted that it is desirable to set the increased temperature to a level where the temperature difference in the long side direction of the pressure roller 33 is reduced to a level that will not cause fixing defects. Furthermore, it is desirable to set the increased temperature to a level that prevents various temperature changes caused by the heating of heater 32 from causing deformation of components. Additionally, in order to minimize the decrease in productivity, it is desirable to limit the amount of speed reduction relative to the standard speed to the required minimum. It should be noted that, as an example, when the standard temperature is changed according to the printing conditions as described above, the increased temperature is defined as a temperature higher than any of these multiple standard temperatures. Therefore, the computer, with the processor 1041 as its central unit, functions as a setting unit by performing information processing based on the information processing program.

[0089] As ACT9, processor 1041 instructs print controller 81 to begin printing based on print data imported in ACT1. Print controller 81 operates its components according to this instruction from system controller 104 to print the original document represented by the print data onto printing paper. This operation can be, for example, the same as that performed by other printers of the same type. Specifically, print controller 81 instructs fuser controller 85 to increase the control temperature of fuser unit 3. Additionally, print controller 81 instructs forming controller 82, exposure controller 83, reversal controller 86, and motor controller 87 to decrease the printing speed.

[0090] As in ACT10, processor 1041 waits for the completion of printing indicated in ACT9. Then, if processor 1041 is notified of printing completion from print controller 81, it determines "yes" and proceeds to ACT11.

[0091] As ACT11, processor 1041 instructs print controller 81 to restore the settings changed in ACT8. For example, processor 1041 instructs print controller 81 to restore the control temperature and print speed to standard temperature and speed. Then, processor 1041 terminates the print control process.

[0092] As shown above, the MFP100 sets the temperature control to increase and the printing speed to decrease during continuous printing using narrow-width printing paper.

[0093] Figure 7 This is a graph showing the results of temperature measurements of the fixing belt 30 at multiple locations along its long side. Figure 8 This is a graph showing the results of temperature measurements taken at multiple locations along the long side of the pressure roller 33. Figure 7 and Figure 8 This indicates the temperature measurement result when printing is performed in the same task.

[0094] Figure 7 and Figure 8 Besides changing the temperature and printing speed controls to increasing the temperature and decreasing the speed, the other changes are... Figure 5 and Figure 6 Under the same measurement conditions.

[0095] The maximum temperature difference of the pressure roller 33 in sheet 50 and Figure 6 Compared to ΔTA in the middle, Figure 8 The ΔTB in the figure is reduced. Therefore, the difference in outer diameter corresponding to the position of the pressure roller 33 along its long side is suppressed less compared to the case where the temperature and printing speed are directly maintained at the standard temperature and speed.

[0096] Figure 9 This is a graph showing the relationship between the controlled temperature and printing speed and the temperature difference corresponding to the position of the pressure roller 33 along its long side.

[0097] according to Figure 9 It can be seen that the greater the temperature control and the lower the printing speed, the smaller the temperature difference becomes. As a result, as mentioned above, the temperature difference ΔTB is smaller than the temperature difference ΔTA.

[0098] Figure 10 It is a graph showing the relationship between the temperature difference and the outer diameter difference corresponding to the position of the pressure roller 33 along its long side.

[0099] according to Figure 10 It can be seen that the smaller the temperature difference, the smaller the outer diameter difference. Therefore, since the temperature difference ΔTA is reduced as described above, the outer diameter difference corresponding to the position of the pressure roller 33 in the long side direction is suppressed to a small extent.

[0100] Therefore, according to MFP100, the difference in pressing pressure corresponding to the position of the pressure roller 33 in the long side direction is reduced, which can reduce the possibility of poor fixing.

[0101] Furthermore, the MFP100 does not reduce printing speed when using non-narrow-width paper or when printing in large volumes. Therefore, the reduction in printing speed is limited to a subset of tasks, minimizing the decrease in productivity.

[0102] Furthermore, if the MFP100 sets the temperature and print speed to increase and decrease before printing for a task begins, it will maintain these settings until the printing for that task ends. Therefore, the likelihood of fixing defects is reduced throughout all printing related to that task.

[0103] Figure 11 It is a graph showing the relationship between temperature control, printing speed, and offset level.

[0104] according to Figure 11 It can be seen that there is a trend to reduce the offset level by increasing the control temperature and decreasing the printing speed. It should be noted that the offset level refers to the visual evaluation of the impact on image quality caused by the re-attachment of developer from the fixing belt 30 to the printing paper. It should be noted that, for example, if the offset level is below OAA, the afterimage is reduced to an acceptable level, and setting the printing speed to 50 CPM or below is effective.

[0105] This implementation method can be adapted to various variations, such as those described below.

[0106] As Figure 4 In ACT8, the processor 1041 can also instruct the print controller 81 to change only the settings related to temperature control. In other words, the printing speed can also be kept at the standard speed.

[0107] As ACT9, processor 1041 may also, due to certain circumstances, change at least one of the control temperature and printing speed during the period from the indication of printing start to the confirmation of printing completion in ACT10.

[0108] Print control processing can also be performed by the processor provided by the print controller 81.

[0109] The fixing unit 3 can also be modified to any configuration, such as using a roller to replace the fixing belt 30, or vice versa, using a belt to replace the pressure roller 33, as long as it has the function of heating and pressing the paper.

[0110] Furthermore, some or all of the functions implemented by the processor 1041 through information processing can be implemented by hardware such as logic circuits that perform information processing that is not program-based. In addition, each of the above-mentioned functions can be implemented by combining the aforementioned hardware such as logic circuits with software control.

[0111] While several embodiments have been described, these embodiments are merely illustrative and not intended to limit the scope of the invention. These embodiments can be implemented in various other ways, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included within the scope and spirit of the invention, and likewise within the scope of the invention as described in the claims and its equivalents.

Claims

1. An image forming apparatus, characterized in that, have: The heating element heats up the paper being conveyed in the conveying direction over a region orthogonal to the conveying direction. The pressing part applies pressure to the paper heated by the heating part over the entire area in a direction orthogonal to the conveying direction; The detection unit detects the temperature of the pressing part; The control unit controls the heating element to bring the temperature detected by the detection unit close to the control temperature. as well as The setting unit sets a pre-defined standard temperature as the control temperature if either condition 1 or condition 2 is not met before image formation begins for a task; and sets an increased temperature as the control temperature if both condition 1 and condition 2 are met before image formation begins for the task. Condition 1 refers to the number of images formed in the task being a pre-defined number of prints, and condition 2 refers to the paper size used in the task being a pre-defined small-width paper size. The increased temperature is pre-defined to be higher than the standard temperature.

2. The image forming apparatus according to claim 1, characterized in that, When the standard temperature is set to the control temperature, the setting unit also sets the standard speed to the image forming speed; when the increased temperature is set to the control temperature, the setting unit also sets a decreasing speed lower than the standard speed to the image forming speed.

3. The image forming apparatus according to claim 1 or 2, characterized in that, The setting unit maintains the settings associated with a task until the image formation begins, until the task is completed.

4. The image forming apparatus according to claim 1 or 2, characterized in that, The setting unit sets paper with a width smaller than a predetermined width in a direction orthogonal to the conveying direction as small-width paper.

5. The image forming apparatus according to claim 3, characterized in that, The setting unit sets paper with a width smaller than a predetermined width in a direction orthogonal to the conveying direction as small-width paper.

6. The image forming apparatus according to claim 4, characterized in that, When the number of images formed exceeds a predetermined threshold, the setting unit determines that the number of images formed meets the predetermined requirement for a large number of prints.

7. The image forming apparatus according to claim 5, characterized in that, When the number of images formed exceeds a predetermined threshold, the setting unit determines that the number of images formed meets the predetermined requirement for a large number of prints.

8. The image forming apparatus according to claim 1 or 2, characterized in that, The pressing part includes a strip that holds the paper between itself and other components. The detection unit detects the temperature of the belt.

9. The image forming apparatus according to claim 3, characterized in that, The pressing part includes a strip that holds the paper between itself and other components. The detection unit detects the temperature of the belt.

10. The image forming apparatus according to claim 4, characterized in that, The pressing part includes a strip that holds the paper between itself and other components. The detection unit detects the temperature of the belt.

Images