Image forming apparatus, adjustment method, and adjustment program

Abstract

To efficiently adjust a fixing belt.SOLUTION: An image processing apparatus comprises: a pressure roller 59; a driving motor 59B that drives to rotate the pressure roller 59; an endless fixing belt 57; a pressing member 63 that is provided inside the fixing belt 57 and opposite to the pressure roller 59, and forms a nip part N where the fixing belt 57 and the pressure roller 59 are in contact with each other; a pressing force adjustment mechanism that adjusts a pressing force for pressing one of the pressure roller 59 and the pressing member 63 toward the other; and a drive control unit that controls the pressing force adjustment mechanism and the driving motor 59B to rotate the pressure roller 59 with the pressing force reduced compared with a normal value determined as a normal state.SELECTED DRAWING: Figure 4

Description

Technical Field

[0005] , ,

[0001] The present invention relates to an image forming apparatus, an adjustment method, and an adjustment program, and more particularly to an image forming apparatus that fixes toner to a recording medium by pressing and heating the recording medium, an adjustment method executed by the image forming apparatus, and an adjustment program that causes a computer that controls the image forming apparatus to execute the adjustment method.

Background Art

[0002] Image forming apparatuses such as copiers, printers, and facsimile machines are provided with a fixing device that fixes toner to paper by pressing and heating the paper on which an image formed of toner is formed.

[0003] For example, in Japanese Unexamined Patent Application Publication No. 2019-7989, a fixing device that is detachably installed with respect to an image forming apparatus main body and is configured to form a nip portion where a fixing rotating body and a pressing rotating body are in pressure contact and a sheet is conveyed, and a nip pressure variable mechanism that varies the nip pressure of the nip portion between the fixing rotating body and the pressing rotating body are provided. When it is recognized that the fixing device is new, an aging mode is executed in which the nip pressure is varied and the fixing device is driven idly at the timing during non-image formation. Each time the cumulative travel distance or cumulative drive time of the fixing device reaches a predetermined value, an adjustment mode is executed in which the nip pressure is varied and the fixing device is driven idly at the timing during non-image formation. An image forming apparatus is described.

[0004] In the image forming apparatus described in Japanese Unexamined Patent Application Publication No. 2019-7989, the fixing rotating body is configured such that the inner peripheral surface of an endless fixing belt slides on a nip portion forming member. By executing the aging mode, the lubricant interposed between the fixing belt and the nip portion forming member is extended over the entire inner peripheral surface of the fixing belt 21.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2019-7989 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, the image forming apparatus described in Japanese Patent Publication No. 2019-7989 performs an aging mode for a certain period of time, but does not detect whether the lubricant has sufficiently permeated the entire inner surface of the fixing belt. Therefore, in cases where the temperature is low and the viscosity of the lubricant is high, the lubricant may not have sufficiently permeated the entire inner surface of the fixing belt after the aging mode has finished. Conversely, in cases where the temperature is high and the viscosity of the lubricant is low, the lubricant may have sufficiently permeated the entire inner surface of the fixing belt during the aging mode. In this case, the aging mode will be performed for a longer period than necessary.

[0007] One of the objectives of this invention is to provide an image forming apparatus, an adjustment method, and an adjustment program that can efficiently adjust the fixing belt. [Means for solving the problem]

[0008] According to one aspect of this invention, an image forming apparatus comprises: a pressure roller; a drive unit for rotating the pressure roller; an endless fixing belt; a pressing member provided inside the fixing belt and facing the pressure roller, forming a nip portion where the fixing belt and the pressure roller come into contact; a pressing force adjustment mechanism for adjusting the pressing force that presses one of the pressure roller and the pressing member toward the other; and a drive control unit that controls the pressing force adjustment mechanism and the drive unit to rotate the pressure roller while the pressing force is reduced to a normal value defined as the normal state. The drive control unit rotates the pressure roller while the pressing force is reduced to a value lower than normal, such that the rotation speed of the pressure roller is faster than the rotation speed of the pressure roller when the recording medium passes through the nip portion. ru.

[0009] In this configuration, the pressure roller rotates with a pressing force lower than the normal value defined as the normal state. As a result, the frictional force between the fixing belt and the pressing member is lower than the frictional force under normal conditions, causing the fixing belt and the pressing member to slide against each other. Therefore, changes in the frictional force between the fixing belt and the pressing member can be detected more accurately than under normal conditions. Consequently, an image forming apparatus capable of efficiently adjusting the fixing belt can be provided. Furthermore, because the rotation speed of the fixing belt increases, the lubricant present on the inner surface of the fixing belt can spread across the entire inner surface of the fixing belt more quickly.

[0010] Preferably, the drive control unit ensures that the recording medium passes through the nip portion. death Without the pressure applied, rotate the pressure roller with a pressing force lower than the normal value.

[0011] In this configuration, the pressure roller and the fixing belt are in direct contact, thus ensuring a predetermined frictional force between the fixing belt and the pressure roller.

[0012] Preferably, the system further includes a detection unit for detecting the rotational load of the fixing belt, and the drive control unit rotates the pressure roller with a pressing force lower than the normal value until the rotational load detected by the detection unit falls below a predetermined value.

[0013] Following this procedure allows for accurate detection of changes in the rotational load of the anchoring belt.

[0014] Preferably, the drive control unit rotates the pressure roller with a pressing force lower than the normal value, and if the rotational load detected by the detection unit is less than or equal to a predetermined value, the drive control unit stops the pressure roller.

[0015] Following this procedure, when the rotational load of the fixing belt falls below a predetermined value, the pressure roller stops, thus minimizing the time during which the rotational load of the fixing belt changes.

[0016] Preferably, the system further includes a notification means that notifies if the rotational load detected by the detection unit does not fall below a predetermined value within a predetermined time after the drive control unit rotates the pressure roller with a pressing force lower than the normal value.

[0017] Following this procedure, if the rotational load of the fixing belt cannot be changed, a notification will be issued, thus indicating that the image forming apparatus is in an abnormal state.

[0018] Preferably, the system further includes a heating source for heating the fixing belt, and the drive control unit controls the heating source to heat the fixing belt with thermal energy higher than the thermal energy when the recording medium passes through the nip portion, while rotating the pressure roller with a pressing force lower than the normal value.

[0019] In this scenario, the fixing belt will be heated, and the lubrication present on the inner surface of the fixing belt will be affected. Agent The viscosity can be reduced.

[0022] According to another aspect of this invention, the adjustment method is an adjustment method for controlling an image forming apparatus, the image forming apparatus comprising: a pressure roller; a drive unit for rotating the pressure roller; an endless fixing belt; a pressing member provided inside the fixing belt and facing the pressure roller, forming a nip portion where the fixing belt and the pressure roller come into contact; and a pressing force adjustment mechanism for adjusting the pressing force that presses one of the pressure roller and the pressing member toward the other, the method including: a pressing force adjustment step of controlling the pressing force adjustment mechanism to make the pressing force smaller than a normal value defined as the normal state; and a drive control step of controlling the drive unit to rotate the pressure roller while the pressing force is smaller than the normal value. Furthermore, the drive control step includes rotating the pressure roller while the pressing force is reduced to a normal value, such that the rotational speed of the pressure roller is faster than the rotational speed of the pressure roller when the recording medium passes through the nip portion. nothing.

[0023] Following this approach, it is possible to provide an adjustment method that allows for efficient adjustment of the fixing belt.

[0024] According to still another aspect of the present invention, the adjustment program is an adjustment program executed by a computer that controls an image forming apparatus. The image forming apparatus includes a pressure roller, a drive unit that rotationally drives the pressure roller, an endless fixing belt, a pressing member provided inside the fixing belt and facing the pressure roller to form a nip portion where the fixing belt and the pressure roller contact each other, and a pressing force adjustment mechanism that adjusts a pressing force for pressing one of the pressure roller and the pressing member toward the other. The adjustment program causes the computer to execute a pressing force adjustment step of controlling the pressing force adjustment mechanism to make the pressing force smaller than a normal value defined as a normal state, and a drive control step of controlling the drive unit to rotate the pressure roller in a state where the pressing force is smaller than the normal value. The drive control step includes rotating the pressure roller while the pressing force is reduced to a normal value, such that the rotational speed of the pressure roller is faster than the rotational speed of the pressure roller when the recording medium passes through the nip portion. .

[0025] According to this aspect, it is possible to provide an adjustment program capable of efficiently adjusting the fixing belt.

Brief Description of the Drawings

[0026] [Figure 1] It is a first perspective view showing the appearance of a printer in one embodiment of the present invention. [Figure 2] It is a block diagram showing an example of the hardware configuration of the printer. [Figure 3] It is a cross-sectional view schematically showing an example of the internal configuration of the printer. [Figure 4] It is a cross-sectional view of the fixing device. [Figure 5] It is a view showing the pressing force adjustment mechanism. [Figure 6] It is a view showing the pressing force adjustment mechanism. [Figure 7] It is a view showing an example of the change in torque of the drive motor during the adjustment operation. [Figure 8] It is a block diagram showing an example of the functions of the CPU included in the printer in this embodiment. [Figure 9] It is a flowchart showing an example of the flow of the adjustment process. [Modes for carrying out the invention]

[0027] Embodiments of the present invention will be described below with reference to the drawings. In the following description, identical parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed descriptions of them will not be repeated.

[0028] Figure 1 is a first perspective view showing the appearance of a printer in one embodiment of the present invention. Figure 2 is a block diagram showing an example of the hardware configuration of the printer. Referring to Figures 1 and 2, the printer 100 is an example of an image forming apparatus and includes a main circuit 110, an image forming unit 140 for forming an image on paper or the like based on image data, a paper feeding unit 150 for supplying paper to the image forming unit 140, and an operation panel 160 as a user interface.

[0029] The main circuit 110 includes a CPU (Central Processing Unit) 111 that controls the entire printer 100, a communication interface (I / F) unit 112, a ROM (Read Only Memory) 113, a RAM (Random Access Memory) 114, a hard disk drive (HDD) 115 as a large-capacity storage device, and an external storage device 117. The CPU 111 is connected to the image forming unit 140, the paper feeding unit 150, and the operation panel 160, and controls the entire printer 100.

[0030] The paper feeding unit 150 transports the paper stored in the paper cassette to the image forming unit 140. The image forming unit 140 is controlled by the CPU 111 and forms images using a well-known electrophotographic method. Based on the image data input from the CPU 111, it forms an image on the paper transported by the paper feeding unit 150 and discharges the image-formed paper into the output tray 39. The image data that the CPU 111 outputs to the image forming unit 140 includes image data such as print data received from an external personal computer.

[0031] ROM113 stores the program that the CPU111 executes, or the data necessary to execute that program. RAM114 is used as a workspace when the CPU111 executes the program.

[0032] The control panel 160 is located on the top surface of the printer 100. The control panel 160 includes a display unit 161 and an operation unit 163. The display unit 161 is, for example, a liquid crystal display (LCD) and displays instruction menus for the user, information about acquired image data, etc. Instead of an LCD, any device that can display images, such as an organic electroluminescent (EL) display, can be used.

[0033] The operation unit 163 includes a touch panel 165 and a hard key unit 167. The hard key unit 167 includes a plurality of hard keys, which are, for example, contact switches. The touch panel 165 detects the position indicated by the user on the display surface of the display unit 161.

[0034] The communication interface unit 112 is an interface for connecting the printer 100 to the network. The communication interface unit 112 communicates with other computers connected to the network using communication protocols such as TCP (Transmission Control Protocol) or UDP (User Datagram Protocol). The network to which the communication interface unit 112 is connected is a local area network (LAN), and the connection method can be wired or wireless. Furthermore, the network is not limited to a LAN; it may also be a wide area network (WAN), public switched telephone network (PSTN), the internet, etc.

[0035] The external storage device 117 is controlled by the CPU 111 and is equipped with a CD-ROM (Compact Disk Read Only Memory) 118 or semiconductor memory. In this embodiment, an example is described in which the CPU 111 executes a program stored in the ROM 113, but the CPU 111 may also control the external storage device 117 to read a program for execution from the CD-ROM 118, store the read program in the RAM 114, and then execute it.

[0036] Furthermore, the recording medium for storing the program to be executed by the CPU 111 is not limited to the CD-ROM 118, but may also be a flexible disk, cassette tape, optical disc (MO (Magnetic Optical Disc) / MD (Mini Disc) / DVD (Digital Versatile Disc)), IC card, optical card, mask ROM, EPROM (Erasable Programmable ROM), or other semiconductor memory. In addition, the CPU 111 may download the program from a computer connected to the network and store it in the HDD 115, or a computer connected to the network may write the program to the HDD 115, load the program stored in the HDD 115 into the RAM 114, and execute it with the CPU 111. The program referred to here includes not only programs that can be directly executed by the CPU 111, but also source programs, compressed programs, encrypted programs, etc.

[0037] Figure 3 is a schematic cross-sectional view showing an example of the internal structure of a printer. For the purposes of this explanation, the left-right direction in Figure 3 will be referred to as the left-right direction, and the front-back direction will be referred to as the depth direction. In the left-right direction, the direction from left to right will be referred to as the right side direction, and the direction from right to left will be referred to as the left side direction. In the depth direction, the direction from front to back will be referred to as the front direction, and the direction from back to front will be referred to as the back direction.

[0038] Printer 100 is equipped with image forming units 20Y, 20M, 20C, and 20K for yellow, magenta, cyan, and black, respectively. Here, "Y", "M", "C", and "K" represent yellow, magenta, cyan, and black, respectively. Printing data for yellow, magenta, cyan, and black is input to the image forming units 20Y, 20M, 20C, and 20K, respectively. The only difference between the image forming units 20Y, 20M, 20C, and 20K is the color of the toner they handle, so here we will describe the image forming unit 20Y for forming a yellow image.

[0039] The image forming unit 20Y includes an exposure device 21Y into which yellow printing data is input, a photoreceptor drum 23Y which is an image carrier, a charging roller 22Y for uniformly charging the surface of the photoreceptor drum 23Y, a developer 24Y, a primary transfer roller 25Y for transferring the toner image formed on the photoreceptor drum 23Y onto an intermediate transfer belt 30 which is an image carrier by the action of an electric field, a drum cleaning blade 27Y for removing residual toner from the photoreceptor drum 23Y, a toner bottle 41Y, and a toner hopper 42Y.

[0040] The toner bottle 41Y contains yellow toner. The toner bottle 41Y rotates using a toner bottle motor as its drive source and discharges toner to the outside. The toner discharged from the toner bottle 41Y is supplied to the toner hopper 42Y. The toner hopper 42Y supplies toner to the developer unit 24Y in accordance with the amount of toner remaining in the developer unit 24Y, which falls below a predetermined lower limit.

[0041] Around the photoreceptor drum 23Y, the charging roller 22Y, exposure unit 21Y, developer unit 24Y, primary transfer roller 25Y, and drum cleaning blade 27Y are arranged in order along the rotational direction of the photoreceptor drum 23Y.

[0042] The photoreceptor drum 23Y is charged by the charging roller 22Y, and then irradiated with laser light emitted by the exposure device 21Y. The exposure device 21Y exposes the image-corresponding portion of the surface of the photoreceptor drum 23Y to form an electrostatic latent image. This forms an electrostatic latent image on the photoreceptor drum 23Y. Subsequently, the developer 24Y develops the electrostatic latent image formed on the photoreceptor drum 23Y with charged toner. Specifically, toner is placed on the electrostatic latent image formed on the photoreceptor drum 23Y by the action of an electric field force, thereby forming a toner image on the photoreceptor drum 23Y. The toner image formed on the photoreceptor drum 23Y is transferred onto the intermediate transfer belt 30, which is an image carrier, by the action of an electric field force using the primary transfer roller 25Y. Toner that remains on the photoreceptor drum 23Y without being transferred is removed from the photoreceptor drum 23Y by the drum cleaning blade 27Y.

[0043] Meanwhile, the intermediate transfer belt 30 is suspended by the drive roller 33 and the driven roller 34 to prevent slack. When the drive roller 33 rotates counterclockwise in Figure 2, the intermediate transfer belt 30 rotates counterclockwise in the figure at a predetermined speed. As the intermediate transfer belt 30 rotates, the driven roller 34 rotates counterclockwise.

[0044] As a result, the image forming units 20Y, 20M, 20C, and 20K sequentially transfer toner images onto the intermediate transfer belt 30. The timing at which each of the image forming units 20Y, 20M, 20C, and 20K transfers toner images onto the intermediate transfer belt 30 is adjusted by detecting reference marks attached to the intermediate transfer belt 30. In this way, yellow, magenta, cyan, and black toner images are superimposed on the intermediate transfer belt 30.

[0045] The toner image formed on the intermediate transfer belt 30 is transferred to the paper by the action of an electric field force by the secondary transfer roller 26, which is a transfer member. The paper, which is transported by the timing roller 31, is transported to the nip section where the intermediate transfer belt 30 and the secondary transfer roller 26 come into contact. The paper on which the toner image has been transferred is transported to the fuser unit 50, where it is heated and pressurized. This melts the toner and fixes it to the paper. After that, the paper is discharged into the output tray 39.

[0046] A belt cleaning blade 28 is provided upstream of the image forming unit 20Y of the intermediate transfer belt 30. The belt cleaning blade 28 removes toner that remains on the intermediate transfer belt 30 without being transferred to the paper.

[0047] When forming a full-color image, the printer 100 drives all of the image forming units 20Y, 20M, 20C, and 20K. However, when forming a monochrome image, it drives only one of the image forming units 20Y, 20M, 20C, and 20K. It is also possible to form an image by combining two or more of the image forming units 20Y, 20M, 20C, and 20K. Here, we describe an example in which the printer 100 employs a tandem system equipped with image forming units 20Y, 20M, 20C, and 20K, each forming one of the four colors of toner on the paper. However, a four-cycle system in which one photosensitive drum transfers the four colors of toner sequentially to the paper may also be used.

[0048] Multiple sheets of paper are loaded into the paper feed cassette 35. The paper stored in the paper feed cassette 35 is supplied one sheet at a time to the transport path 45 by the ejection roller 36 attached to the paper feed cassette 35, and then sent to the timing roller 31 by the paper feed roller 37. In addition, if one or more sheets of paper are loaded into the manual feed cassette 35A, the one or more sheets of paper loaded into the manual feed cassette 35A are supplied one sheet at a time to the transport path 45 by the ejection roller 36A attached to the manual feed cassette 35A, and then sent to the timing roller 31 by the paper feed roller 37.

[0049] Figure 4 is a cross-sectional view of the fixing device. In Figure 4, the fixing device 50 is shown as a cross-section obtained by cutting the device with the rotation axis 59A of the pressure roller 59 as the normal. Referring to Figure 4, the fixing device 50 includes a heating unit 51 and a pressure roller 59. The heating unit 51 is provided opposite the pressure roller 59 and forms a nip portion N between it and the pressure roller 59. The nip portion N is the part where the heating unit 51 and the pressure roller 59 come into contact. The pressure roller 59 is pressed toward the heating unit 51 with a predetermined pressing force.

[0050] A sheet of paper Pa bearing a toner image To on its surface is transported from below to above the fixing device 50, and the paper Pa passes through the nip section N. While the paper Pa passes through the nip section N, it is heated and pressurized by the pressure roller 59 and the heating section 51, and the toner image To is fixed to the paper Pa.

[0051] The pressure roller 59 consists of a core, an intermediate layer, and a surface layer. In this embodiment, the outer diameter of the pressure roller 59 is 30 mm. The core is made of aluminum or iron, and its thickness is 2 to 3 mm. The intermediate layer is an elastic layer and is formed from a heat-resistant and elastic material such as silicone rubber or silicone sponge. The intermediate layer is preferably about 2 to 5 mm thick. The surface layer is formed from a release material such as a fluorine tube, and the thickness of the surface release layer is preferably about 20 to 80 μm.

[0052] The heating section 51 includes a heating roller 53, a pressurizing section 55, an endless fixing belt 57, and a thermistor 91. The fixing belt 57 is an endless, flexible belt. The fixing belt 57 is suspended by the heating roller 53 and the pressurizing section 55 so as not to slacken. The fixing belt 57 is composed of a base layer and an elastic layer. The base layer is made of a polyimide film with an inner diameter of 40 mm, a width of 340 mm, and a thickness of 70 μm. The elastic layer is made of silicone rubber, preferably with a thickness of about 100 to 150 μm. The surface layer is made of PFA or PTFE, which has release properties, and is a coating with a thickness of about 30 μm. The surface layer is formed by coating the elastic layer with fluororesin.

[0053] The heating roller 53 rotates in accordance with the rotation of the fixing belt 57. Alternatively, the heating roller 53 may be kept stationary, allowing the fixing belt 57 to slide along the surface of the heating roller 53.

[0054] The pressurizing section 55 includes a pressing member 63 and a grease application section 65. The pressing member 63 is made of a heat-resistant resin material and has a shape that has a length at least equal to the maximum paper width to be fixed. The pressing member 63 is fixed to the main frame. The pressing member 63 has a shape in which the portion corresponding to the nip section N approximates the curvature of the pressurizing roller 59. Therefore, the amount of elastic deformation of the pressurizing roller 59 can be reduced while maximizing the area of ​​the nip section N. Because the area of ​​the nip section N can be increased, the time for pressurizing and heating the paper can be increased. Also, because the outer diameter of the pressurizing roller 59 can be reduced to a predetermined value or less, the fixing device 50 can be miniaturized. Also, because the amount of elastic deformation of the pressurizing roller 59 can be reduced, the pressing force applied to the pressurizing roller 59 can be reduced. Therefore, because the strength of the pressurizing roller 59 can be reduced to a predetermined value or less, the wall thickness of the pressurizing roller 59 can be reduced, and the heat capacity can be reduced. Furthermore, because the heat capacity of the pressurizing roller 59 can be reduced, power consumption is reduced.

[0055] A sliding sheet is fixed to the nip portion N side of the pressing member 63 to enhance the sliding properties of the surface of the pressing member 63. The sliding sheet is made of heat-resistant glass cloth coated with fluororesin, and possesses heat resistance, wear resistance, and sliding properties. The fixing belt 57 is in contact with the sliding sheet. Therefore, the degree to which the fixing belt 57 is worn down by friction can be minimized.

[0056] The grease application section 65 stores grease, which is a lubricant, and applies grease to the fixing belt 57 at the part that comes into contact with the fixing belt 57. As the fixing belt 57 passes through the grease application section 65, grease is applied to the inner surface of the fixing belt 57 by friction between the fixing belt 57 and the grease application section 65. As a result, the frictional resistance that the fixing belt 57 receives from the pressing member 63 is reduced, and the load on the fixing belt 57 to rotate around the heating roller 53 and the pressurizing section 55 is reduced.

[0057] The heating roller 53 is a hollow cylindrical component with a heat source 61 built inside. The inner diameter of the heating roller 53 is set to a size that does not come into contact with the heat source 61. The heating roller 53 is made of stainless steel. Because the heating roller 53 is made of stainless steel, strength is ensured and it is easy to process. In this case, the thickness of the heating roller 53 can be around 0.1 mm to 0.2 mm. The heating roller 53 may also be made of aluminum. In this case, it is preferable that the thickness of the heating roller 53 be 0.25 mm or more in order to ensure strength against bending and local deformation. The heating roller 53 may also be made of an iron-based metal such as STKM (carbon steel pipe for machine structures).

[0058] The heat source 61 is, for example, a halogen heater. In this embodiment, two halogen heaters with different emission lengths are used as the heat source 61. Note that the heat source 61 is not limited to halogen heaters, and a resistance heating element or IH (Induction Heating) may also be used.

[0059] When the heat source 61 generates heat, the heating roller 53 is heated, and the temperature of the heating roller 53 rises. The thermistor 91 detects the temperature of the heating roller 53. According to the temperature detected by the thermistor 91, the heat source 61 is controlled to turn on or off, so that the heating roller 53 reaches a predetermined temperature. By making the heating roller 53 thinner, the heat capacity of the heating roller 53 is reduced. Therefore, the rate at which the heating roller 53 heats up becomes faster, so the warm-up time until the heating roller 53 reaches a predetermined temperature can be shortened. In addition, the power consumption of the heat source 61 can be reduced.

[0060] The fixing belt 57 is heated to a predetermined temperature by the heat transferred from the heating roller 53 while in contact with the heating roller 53.

[0061] The pressure roller 59 is rotated by the drive motor 59B. As the pressure roller 59 rotates, the fixing belt 57 rotates in response. The fixing belt 57 is heated by the heating roller 53 while it is rotating. After the fixing belt 57 is heated to a predetermined temperature, the paper Pa carrying the toner image To is controlled to enter the nip section N. As the paper Pa passes through the nip section N, the toner image To is fixed to the paper Pa by heat and pressure.

[0062] In this embodiment, the example shows that the heat from the heating roller 53 is transmitted to the fixing belt 57 by conduction. However, the fixing belt 57 may also be heated using radiant heat emitted from the heating roller 53. In this case, the fixing belt 57 and the heating roller 53 do not need to be in contact. Therefore, the fixing belt 57 does not need to be suspended by the heating roller 53 and the pressurizing section 55. Specifically, the fixing belt 57 is pressurized between the pressurizing section 55 and the pressurizing roller 59 and supported by the pressurizing section 55 and the pressurizing roller 59. In addition, the fixing belt 57 slides against the pressing member 63 as the pressurizing roller 59 rotates. As a result, the fixing belt 57 rotates around the pressurizing section 55 and the heating roller 53.

[0063] The heating roller 53 may also be positioned outside the fixing belt 57. In this case, the fixing belt 57 rotates around the pressurizing section 55. Furthermore, the heating roller 53 does not need to be cylindrical; an induction heating device or a ceramic heater that functions as a heat source can be used.

[0064] In this embodiment, the printer 100 is equipped with a pressure adjustment mechanism 70 that adjusts the pressure applied by the pressure roller 59 to the heating section 51.

[0065] Figures 5 and 6 show the pressure adjustment mechanism. Referring to Figures 5 and 6, the pressure adjustment mechanism 70 includes a pressure frame 71, a lever member 73, a load variable gear 75, and a spring 77. The pressure section 55 is fixedly supported at both ends by the main frame.

[0066] The pressure frame 71 is pivotally supported so as to be rotatable around the pressure frame rotation axis 71A. The pressure frame rotation axis 71A is fixedly supported by the main frame. The pressure frame 71 pivotally supports the rotation axis 59A of the pressure roller 59. Therefore, the rotation axis 59A of the pressure roller 59 is rotatable around the pressure frame rotation axis 71A. The pressure frame 71 also has a first connecting portion 71B which is connected to one end of the spring 77.

[0067] The lever member 73 is pivotally supported so as to be rotatable around the lever member rotation axis 73A. The lever member rotation axis 73A is fixedly supported by the main frame. The lever member 73 also has a second connecting portion 73C which is connected to the other end of the spring 77. The spring 77 biases in a direction that shortens the distance between the first connecting portion 71B and the second connecting portion 73C. As a result, the pressure frame 71 is biased by the spring 77 in a counterclockwise direction around the pressure frame rotation axis 71A, and the lever member 73 is biased by the spring 77 in a clockwise direction around the lever member rotation axis 73A. Consequently, the pressure roller 59 is pressed toward the heating portion 51.

[0068] The variable load gear 75 has a gear rotation shaft 75A pivotally supported on the main frame and an adjustment rod 75B parallel to the gear rotation shaft 75A. The variable load gear 75 is rotated by the drive motor 59B and rotates around the gear rotation shaft 75A.

[0069] The lever member 73 has an adjustment hole 73B through which the adjustment rod 75B of the variable load gear 75 passes. When the variable load gear 75 rotates clockwise, the adjustment rod 75B comes into contact with the side surface of the adjustment hole 73B and then slides. As a result, the lever member 73 rotates around the lever member rotation axis 73A. This pulls the other end of the spring 77, increasing the biasing force of the spring 77. Therefore, the pressing force that presses the pressure roller 59 toward the heating section 51 increases.

[0070] In this embodiment, the printer 100 performs an adjustment operation in addition to the image forming operation that forms an image on the paper. The adjustment operation is a separate operation from the image forming operation. The adjustment operation is an operation that controls the fuser 50 when no image is being formed on the paper. The adjustment operation is performed when adjusting the fuser 50 before the printer 100 is shipped, or when adjusting the fuser 50 after replacing the fuser 50 or the fuser belt 57.

[0071] Here, we will explain the adjustment operation. In the state before adjustment, the fuser unit 50 does not have grease spread over the entire inner surface of the fuser belt 57. When the fuser unit 50 is driven in this state, the frictional force that the fuser belt 57 receives from the part that contacts the pressing member 63 is greater than the frictional force that the fuser belt 57 receives when grease is spread over the entire inner surface. As a result, there is a possibility that the rotation of the fuser belt 57 and the rotation of the pressure roller 59 will not be synchronized. Therefore, if the image forming operation is performed without performing the adjustment operation, the speed at which the fuser unit 50 transports the paper will be slower than the speed at which the paper passes through the nip section where the intermediate transfer belt 30 and the secondary transfer roller 26 contact. Because a difference in transport speed occurs in two consecutive sections, the paper bends between the nip section where the intermediate transfer belt 30 and the secondary transfer roller 26 contact and the fuser unit 50, which may cause the toner image formed on the paper to come into contact with other parts and be destroyed, or the paper to get caught inside the fuser unit 50.

[0072] The adjustment operation involves rotating the fuser belt 57 freely while the recording medium does not pass through the fuser unit 50. When the adjustment operation is performed, grease is spread evenly over the entire inner surface of the fuser belt 57. The adjustment operation is performed in response to a predetermined instruction input from an external source. The instruction input from an external source may be, for example, an operation entered by a user operating the printer 100, or a command received from a computer connected to the printer 100.

[0073] Figure 7 shows an example of the torque change of the drive motor during adjustment. The graph shown by the thin line represents the torque change of the drive motor 59B when the pressing force with which the pressure roller 59 presses the heating section 51 is set to the first pressing force. The graph shown by the thick line represents the torque change of the drive motor 59B when the pressing force with which the pressure roller 59 presses the heating section 51 is set to the second pressing force, which is smaller than the first pressing force. The second range of torque change of the drive motor 59B in the case of the second pressing force is larger than the first range of torque change of the drive motor 59B in the case of the first pressing force.

[0074] When the fixing belt 57 is rotating freely, the fixing belt 57 slides against the pressing member 63 and the grease application portion 65. The portion of the pressing member 63 that constitutes the nip portion N is a part of the portion of the pressing member 63 that slides against the fixing belt 57. Here, the portion of the pressing member 63 that constitutes the nip portion N is called the nip component.

[0075] The rotational load on the fixing belt 57 consists of the frictional force received from the pressing member 63 and the grease application portion 65, and the moment of inertia of the heating roller 53. The moment of inertia of the heating roller 53 is constant. The frictional force received by the fixing belt 57 from the nip component fluctuates if the pressing force applied by the pressure roller 59 to the heating portion 51 fluctuates. The frictional force received by the fixing belt 57 from the portion of the pressing member 63 other than the nip component and from the grease application portion 65 does not fluctuate even if the pressing force applied by the pressure roller 59 to the heating portion 51 fluctuates.

[0076] Here, let FR1 be the frictional force that the fixing belt 57 receives from the nip component, and FR2 be the frictional force that the fixing belt 57 receives from the part of the pressing member 63 other than the nip component and the grease application part 65. FR1 is larger as the pressing force applied by the pressure roller 59 against the heating part 51 increases. Therefore, the ratio of FR2 to FR1 (FR2 / FR1) increases as the pressing force applied by the pressure roller 59 against the heating part 51 decreases.

[0077] As described above, the load on the fixing belt 57 is detected as the torque of the drive motor 59B. Therefore, the amount of variation in FR2 is expressed as a variation in the torque of the drive motor 59B. The smaller the ratio of FR2 to FR1, in other words, the smaller the pressing force with which the pressure roller 59 presses the heating section 51, the larger the proportion of the amount of variation in FR2 that accounts for the load on the fixing belt 57. For this reason, when detecting the amount of variation in FR2, the smaller the pressing force with which the pressure roller 59 presses the heating section 51, the more accurately the amount of variation in FR2 can be detected.

[0078] Therefore, in this embodiment, when the printer 100 performs an adjustment operation, the pressure applied by the pressure roller 59 to the heating unit 51 is set to a level smaller than the pressure applied when performing an image forming operation, causing the fixing belt 57 to rotate freely.

[0079] Figure 8 is a block diagram showing an example of the functions of the CPU in the printer in this embodiment. The functions shown in Figure 8 are functions realized by the CPU 111 of the printer 100 when the CPU 111 executes adjustment programs stored in the ROM 113, HDD 115, or CD-ROM 118. Referring to Figure 8, the CPU 111 of the printer 100 includes a fuser control unit 251 that controls the fuser unit 50, a comparison unit 253, and a notification unit 255.

[0080] The fixing device control unit 251 includes a pressing force adjustment unit 261, a temperature adjustment unit 263, and a drive control unit 265.

[0081] The pressure adjustment unit 261 controls the pressure adjustment mechanism 70 to adjust the pressure applied by the pressure roller 59 to the pressing member 63. The pressure adjustment unit 261 adjusts the pressure applied by the pressure roller 59 to the pressing member 63 by rotating the load variable gear 75. The pressure applied by the pressure roller 59 to the pressing member 63 is defined as a first pressure during the image forming operation and a second pressure during the adjustment operation. The second pressure is lower than the first pressure. The first pressure is defined for each of several types of paper. Therefore, the first pressure has a certain range. The second pressure is smaller than the minimum value of the first pressure. During the image forming operation, the pressure adjustment unit 261 rotates the load variable gear 75 so that the pressure applied by the pressure roller 59 to the pressing member 63 becomes the first pressure. Furthermore, during the adjustment operation, the pressure adjustment unit 261 rotates the load variable gear 75 so that the pressure applied by the pressure roller 59 to the pressure member 63 becomes the second pressure.

[0082] The temperature control unit 263 controls the heat source 61 to adjust the temperature of the heating roller 53. When the temperature control unit 263 turns on the heat source 61, the temperature of the heating roller 53 rises, and when the heat source 61 is turned off, the temperature of the heating roller 53 falls. The temperature control unit 263 receives the temperature of the heating roller 53 detected by the thermistor 91 as input. The temperature control unit 263 adjusts the temperature of the heating roller 53 by controlling the on / off state of the heat source 61 based on the temperature detected by the thermistor 91.

[0083] The temperature of the heating roller 53 is defined as a first temperature during image formation and a second temperature during adjustment. The second temperature is higher than the first temperature. The first temperature is defined separately for multiple types of paper. Therefore, the first temperature has a certain range. The second temperature is greater than the maximum value of the first temperature. During image formation, the temperature adjustment unit 263 controls the heat source 61 on / off so that the temperature of the heating roller 53 is at the first temperature. During adjustment, the temperature adjustment unit 263 controls the heat source 61 on / off so that the temperature of the heating roller 53 is at the second temperature.

[0084] The drive control unit 265 controls and drives the drive motor 59B. The drive control unit 265 includes a speed adjustment unit 271 and a detection unit 273. The speed adjustment unit 271 adjusts the rotational speed of the drive motor 59B. Specifically, the speed adjustment unit 271 drives the drive motor 59B so that the rotational speed of the pressure roller 59 remains constant. The rotational speed of the pressure roller 59 is detected by an encoder.

[0085] The rotational speed of the pressure roller 59 is defined as a first rotational speed during image formation and a second rotational speed during adjustment. The second rotational speed is greater than the first rotational speed. The first rotational speed is defined separately for multiple types of paper. Therefore, the first rotational speed has a certain range. The second rotational speed is greater than the maximum value of the first rotational speed. The speed adjustment unit 271 controls the drive motor 59B so that the pressure roller 59 rotates at the first rotational speed during image formation. The speed adjustment unit 271 also controls the drive motor 59B so that the pressure roller 59 rotates at the second rotational speed during adjustment.

[0086] The detection unit 273 detects the load on the fixing belt 57. The detection unit 273 detects the load on the fixing belt 57 by detecting the torque of the drive motor 59B. In this embodiment, the drive control unit 265 controls the drive motor 59B with current. The detection unit 273 detects the load on the fixing belt 57 based on the current flowing through the drive motor 59B that rotates the pressure roller 59. The load on the fixing belt 57 is the load required to rotate the fixing belt 57 at a constant speed, and is also called the rotational load. If the fixing belt 57 and the pressure roller 59 do not slip, the load on the fixing belt 57 can be considered to be the same as the torque required to rotate the pressure roller 59 at a constant speed. The detection unit 273 detects the torque required to rotate the pressure roller 59 at a constant speed as the load on the fixing belt 57. The value of the current flowing through the drive motor 59B has a predetermined relationship with the torque required to rotate the pressure roller 59 at a constant speed. The detection unit 273 uses the relationship between current and torque, which has been determined in advance through experiments, to detect the torque required to rotate the pressure roller 59 at a constant speed from the current value input from the drive control unit 265. The detection unit 273 outputs the torque required to rotate the pressure roller 59 at a constant speed to the comparison unit 253.

[0087] The comparison unit 253 receives the torque of the pressure roller 59 from the detection unit 273. During the adjustment operation, the comparison unit 253 compares the torque of the pressure roller 59 with a threshold value TH and outputs the comparison result to the drive control unit 265 and the notification unit 255. The threshold value TH corresponds to the load on the fixing belt 57 when grease is spread over the entire inner surface of the fixing belt 57. The threshold value TH is a value obtained by experiment or simulation. If the torque of the pressure roller 59 is greater than the threshold value TH, it can be determined that the state is before grease is spread over the inner surface of the fixing belt 57. Also, if the torque of the pressure roller 59 is less than or equal to the threshold value TH, it can be determined that grease is spread over the entire inner surface of the fixing belt 57. If the rotational load of the fixing belt 57 is greater than the threshold value TH, the comparison unit 253 outputs an unreached signal to the drive control unit 265 and the notification unit 255 indicating that the state is before grease is spread over the inner surface of the fixing belt 57. The comparison unit 253 outputs a completion signal to the drive control unit 265 and the notification unit 255 indicating that the grease has been spread evenly on the inner surface of the fixing belt 57 when the rotational load of the fixing belt 57 is below the threshold TH.

[0088] The notification unit 255 receives either a non-delivery signal or a completion signal from the comparison unit 253 during the adjustment operation. The notification unit 255 notifies if the adjustment operation is abnormal. Specifically, the notification unit 255 notifies if a completion signal is not received from the comparison unit 253 within a predetermined time after the adjustment operation has started. For example, the notification unit 255 displays on the display unit 161 that the fuser 50 is in an abnormal state. The notification unit 255 displays a message, icon, etc., on the display unit 161. The notification unit 255 may also notify by emitting sound from a speaker. The notification unit 255 may also output data to an external device indicating that the fuser 50 is in an abnormal state. Furthermore, the notification unit 255 may send electronic data, such as email, to an administrator.

[0089] Figure 9 is a flowchart illustrating an example of the adjustment process flow. The adjustment process is performed by the CPU 111 of the printer 100 by executing an adjustment program stored in the ROM 113, HDD 115, or CD-ROM 118. Referring to Figure 8, the CPU 111 of the printer 100 controls the pressure adjustment mechanism 70 and sets the pressure applied by the pressure roller 59 to the pressure member 63 to a second pressure (step S01). The second pressure is smaller than the first pressure set during the image forming operation.

[0090] In the next step S02, the pressure roller 59 is set to rotate at a second rotational speed, and the process proceeds to step S03. The rotational speed of the drive motor 59B is set to rotate at a second rotational speed. The second rotational speed is greater than the first rotational speed set during the image forming operation.

[0091] In step S03, the temperature of the heating roller 53 is set to a second temperature, and the process proceeds to step S04. The heat source 61 is controlled so that the temperature of the heating roller 53 reaches the second temperature. As a result, the heat source 61 is turned on / off so that the temperature detected by the thermistor 91 maintains the second temperature. The second temperature is higher than the first temperature set during the image forming operation.

[0092] In step S04, the drive motor 59B is driven, and the process proceeds to step S05. The drive motor 59B rotates so that the pressure roller 59 rotates at the second rotational speed set in step S02. As a result, the fixing belt 57 starts to rotate.

[0093] In step S05, the torque value TR of the drive motor 59B is detected, and the process proceeds to step S06. In step S06, the torque value TR of the drive motor 59B is compared with a threshold value TH. If the torque value TR is less than or equal to the threshold value TH, the process proceeds to step S07; otherwise, the process proceeds to step S08. In step S07, the drive motor 59B is stopped, and the adjustment process is completed.

[0094] In step S08, it is determined whether a predetermined time has elapsed since the drive motor 59B was started. If the predetermined time has elapsed since the drive motor 59B was started, the process proceeds to step S09; otherwise, the process returns to step S05. In step S09, the drive motor 59B is stopped, and the process proceeds to step S10.

[0095] In step S10, an error is reported, and the adjustment process ends.

[0096] As described above, the printer 100 in this embodiment functions as an image forming apparatus. The printer 100 includes a pressure roller 59, a drive motor 59B that rotates the pressure roller 59, an endless fixing belt 57, a pressing member 63 provided inside the fixing belt 57 and facing the pressure roller 59, forming a nip portion N where the fixing belt 57 and the pressure roller 59 come into contact, and a pressing force adjustment mechanism 70 that adjusts the pressing force that presses the pressure roller 59 toward the pressing member 63. The CPU 111 controls the pressing force adjustment mechanism 70 and the drive motor 59B to rotate the pressure roller 59 with a second pressing force that is smaller than the first pressing force during image forming operation, which is the normal value. The printer 100 also includes a drive control unit. As the pressure roller 59 is rotated with a second pressing force applied to it toward the pressing member 63, the frictional force between the fixing belt 57 and the pressing member 63 is reduced to less than the frictional force during the normal image forming operation, allowing the fixing belt 57 and the pressing member 63 to slide against each other. Therefore, changes in the frictional force between the fixing belt 57 and the pressing member 63 can be detected more accurately than during the normal image forming operation. Consequently, the state in which grease is spread across the entire inner surface of the fixing belt 57 can be detected more accurately than during image forming, allowing the fixing belt 57 to be adjusted more efficiently.

[0097] Furthermore, during adjustment operations where the paper does not pass through the nip section N, the CPU 111 rotates the pressure roller 59 with a second pressure that is smaller than the first pressure, which is the normal value during image formation. As a result, the pressure roller 59 and the fixing belt 57 are in direct contact, ensuring a predetermined frictional force between the fixing belt 57 and the pressure roller 59.

[0098] Furthermore, the CPU 111 detects the rotational load of the fixing belt 57 as the rotational torque of the drive motor 59B, and rotates the pressure roller 59 with the torque value TR set to a second pressing force until the torque value reaches the threshold TH. This allows for accurate detection of changes in the rotational load of the fixing belt 57.

[0099] Furthermore, the CPU 111 rotates the pressure roller 59 with the pressing force set to the second pressing force, and if the torque value TR detected as the rotational torque of the drive motor 59B is below the threshold TH, the CPU 111 stops the pressure roller 59. Therefore, when the rotational load of the fixing belt 57 falls below a predetermined value, the pressure roller 59 is stopped, thus minimizing the adjustment operation time. The adjustment operation is the operation of spreading the grease applied to the inner surface of the fixing belt 57.

[0100] Furthermore, if the torque value TR detected as the rotational torque of the drive motor 59B within a predetermined time after rotating the pressure roller 59 while the pressure roller 59 is pressurized by the second pressing force does not reach the threshold TH, a notification is issued. Therefore, if the rotational load of the fixing belt 57 cannot be reduced, a notification is issued, allowing the printer 100 to notify of an abnormal condition.

[0101] Furthermore, the printer 100 is equipped with a heat source 61 and a heating roller 53 for heating the fuser belt 57. During adjustment, the CPU 111 controls the heat source 61 to heat the fuser belt 57 to a second temperature, which is higher than the first temperature during image forming, while the pressure roller 59 is rotated with a second pressing force applied to the pressure roller 59. As a result, the fuser belt 57 is heated, which can lower the viscosity of the grease present on the inner surface of the fuser belt.

[0102] Furthermore, during adjustment operations, the printer 100 rotates the pressure roller 59 at a second rotational speed that is faster than the first rotational speed of the pressure roller 59 during image forming operations, while the pressure roller 59 is pressed with a second pressing force. As a result, the rotational speed of the fixing belt 57 increases, allowing the grease present on the inner surface of the fixing belt 57 to spread quickly across the entire inner surface of the fixing belt 57.

[0103] <First variation> The adjustment operation described above is performed when the fuser unit 50 is adjusted before the printer 100 is shipped, or when the fuser unit 50 or fuser belt 57 is replaced, but is not limited to these cases. The adjustment operation may also be performed under predetermined conditions after the printer 100 has performed an image forming operation. For example, it may be performed at the timing when a predetermined number of images are formed on the recording medium by the printer 100. When a predetermined number of images are formed on the recording medium by the printer 100, dust may enter the inner surface of the fuser belt 57, causing an uneven distribution of grease. In such cases, performing the adjustment operation can ensure that grease is distributed evenly across the entire inner surface of the fuser belt 57.

[0104] Furthermore, the adjustment operation may be performed after a predetermined period of time has passed during which the fixing device 50 has not been driven. The inner circumferential surface of the fixing belt 57 has parts that come into contact with the pressing member 63, the grease application part 65, and the heating roller 53, and parts that do not come into contact with other members. For this reason, if a predetermined period of time has passed without the fixing device 50 being driven, the distribution of grease on the inner circumferential surface of the fixing belt 57 may become uneven. In such cases, performing the adjustment operation will ensure that grease is distributed evenly across the entire inner circumferential surface of the fixing belt 57.

[0105] Furthermore, the adjustment operation may be performed when the power is turned on during startup, such as in winter when the temperature is below a predetermined value. Because the viscosity of the grease applied to the inner surface of the fixing belt 57 decreases, if the fixing device 50 is driven when the grease temperature is low, the distribution of grease on the inner surface of the fixing belt 57 may become uneven. In such cases, performing the adjustment operation will ensure that the grease is distributed evenly across the entire inner surface of the fixing belt 57.

[0106] <Second variation> In this embodiment, during the adjustment operation, the pressing force applied by the pressure roller 59 to the pressing member 63 is set to a second pressing force, the rotational speed of the pressure roller 59 is set to a second rotational speed, and the temperature of the heating roller 53 is set to a second temperature. However, the embodiment is not limited to this. During the adjustment operation, it is sufficient that the pressing force applied by the pressure roller 59 to the pressing member 63 is set to a second pressing force. In this case, the rotational speed of the pressure roller 59 may be set to a first rotational speed, and the temperature of the heating roller 53 may be set to a first temperature.

[0107] Alternatively, during the adjustment operation, the pressing force applied by the pressure roller 59 to the pressing member 63 may be set to a second pressing force, the rotational speed of the pressure roller 59 may be set to a second rotational speed, and the temperature of the heating roller 53 may be set to a first temperature.

[0108] <Third variation> In this embodiment, the pressure roller 59 is pressed against the heating unit 51, but the heating unit 51 may also be pressed against the pressure roller 59.

[0109] <Fourth variation> In this embodiment, the case in which the pressure roller 59 is driven and the fixing belt 57 rotates in its own way has been described as an example, but the pressure roller 59 may also rotate in its own way. In this case, a motor that rotates the heating roller 53 is provided instead of the drive motor 59B.

[0110] <Fifth variation> In this embodiment, an example is shown in which the pressure roller 59 is pressed against the fixing belt 57. However, when the fixing device 50 is not running, the pressure roller 59 may be separated from the fixing belt 57. Preferably, the pressure roller 59 is pressed against the heating unit 51 at least while the paper is passing through the nip section N. This makes it possible to limit the period during which the pressure roller 59 undergoes elastic deformation to the time it is passing through the recording medium.

[0111] Furthermore, although a printer 100 was described as an example of an image forming apparatus in this embodiment, the image forming apparatus may also be a copier, a laser beam printer, a facsimile machine, or a multifunction device (Multi Function Peripheral) that combines these.

[0112] Furthermore, in this embodiment, a tandem-type color image forming printer 100 was described as an example of an image forming apparatus, but it is not limited to this, and an image forming apparatus that forms monochrome images may also be used. The configuration and arrangement of the image forming units 20Y, 20M, 20C, 20K, exposure apparatus 21Y, 21M, 21C, 21K, charging rollers 22Y, 22M, 22C, 22K, photoreceptor drums 23Y, 23M, 23C, 23K, developer 24Y, 24M, 24C, 24K, primary transfer rollers 25Y, 25M, 25C, 25K, secondary transfer roller 26, and fixing apparatus 50 are not limited to this embodiment, and other configurations and arrangements may be used.

[0113] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the foregoing description, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of symbols]

[0114] 100 Printer, 111 CPU, 140 Image forming unit, 150 Paper feeding unit, 50 Fixing device, 51 Heating unit, 53 Heating roller, 55 Pressure unit, 57 Fixing belt, 59 Pressure roller, 59A Rotating shaft, 59B Drive motor, 61 Heat source, 63 Pressing member, 65 Grease application unit, 70 Pressing force adjustment mechanism, 91 Thermistor, 111 CPU, 112 Communication I / F unit, 113 ROM, 114 RAM, 115 HDD, 117 External storage device, 118 CD-ROM, 251 Fixing device control unit, 253 Comparison unit, 255 Notification unit, 261 Pressing force adjustment unit, 263 Temperature adjustment unit, 265 Drive control unit, 271 Speed ​​adjustment unit, 273 Detection unit, N Nip unit.

Claims

1. Pressure roller and A drive unit that rotates the aforementioned pressure roller, An endless fixing belt, A pressing member is provided on the inside of the fixing belt and facing the pressure roller, forming a nip portion where the fixing belt and the pressure roller come into contact; A pressing force adjustment mechanism for adjusting the pressing force applied to one of the pressure roller and the pressing member toward the other, The system includes a drive control unit that controls the pressing force adjustment mechanism and the drive unit to rotate the pressure roller while the pressing force is reduced to a normal value defined as the normal state, Image forming apparatus, wherein the drive control unit rotates the pressure roller while the pressing force is reduced to a value less than the normal value, such that the rotational speed of the pressure roller is faster than the rotational speed of the pressure roller when the recording medium passes through the nip portion.

2. The image forming apparatus according to claim 1, wherein the drive control unit rotates the pressure roller with the pressing force reduced to a value less than the normal value while the recording medium does not pass through the nip portion.

3. The system further includes a detection unit for detecting the rotational load of the fixing belt, The image forming apparatus according to claim 1 or 2, wherein the drive control unit rotates the pressure roller with the pressing force reduced to a lower than the normal value until the rotational load detected by the detection unit falls below a predetermined value.

4. The image forming apparatus according to claim 3, wherein the drive control unit rotates the pressure roller with the pressing force reduced to a normal value, and stops the pressure roller if the rotational load detected by the detection unit is less than or equal to a predetermined value.

5. The image forming apparatus according to claim 3, further comprising a notification means for notifying if the rotational load detected by the detection unit does not fall below a predetermined value within a predetermined time after the drive control unit rotates the pressure roller with the pressing force reduced to a value less than the normal value.

6. The system further includes a heating source for heating the aforementioned fixing belt, The image forming apparatus according to claim 1 or 2, wherein the drive control unit controls the heating source to heat the fixing belt with thermal energy higher than the thermal energy when the recording medium passes through the nip portion, while the pressure roller is rotated with the pressing force reduced to a value lower than the normal value.

7. A method for adjusting an image forming apparatus, The image forming apparatus includes a pressure roller and A drive unit that rotates the aforementioned pressure roller, An endless fixing belt, A pressing member is provided on the inside of the fixing belt and facing the pressure roller, forming a nip portion where the fixing belt and the pressure roller come into contact; The system includes a pressing force adjustment mechanism that adjusts the pressing force applied to one of the pressure roller and the pressing member toward the other, A pressing force adjustment step involves controlling the pressing force adjustment mechanism to make the pressing force smaller than a normal value defined as the normal state, The drive control step includes controlling the drive unit to rotate the pressure roller while the pressing force is less than the normal value, The drive control step is an adjustment method that includes rotating the pressure roller such that, while the pressure is reduced to a normal value, the rotational speed of the pressure roller is faster than the rotational speed of the pressure roller when the recording medium passes the nip portion.

8. An adjustment program executed by a computer that controls an image forming apparatus, The image forming apparatus includes a pressure roller and A drive unit that rotates the aforementioned pressure roller, An endless fixing belt, A pressing member is provided on the inside of the fixing belt and facing the pressure roller, forming a nip portion where the fixing belt and the pressure roller come into contact; The system includes a pressing force adjustment mechanism that adjusts the pressing force applied to one of the pressure roller and the pressing member toward the other, A pressing force adjustment step involves controlling the pressing force adjustment mechanism to make the pressing force smaller than a normal value defined as the normal state, The computer is instructed to perform a drive control step of controlling the drive unit so that the pressing force is less than the normal value and the pressure roller is rotated. The drive control step includes an adjustment program that rotates the pressure roller such that, while the pressure is reduced to a normal value, the rotational speed of the pressure roller is faster than the rotational speed of the pressure roller when the recording medium passes the nip portion.

Images