JP2012118114A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To appropriately detect a temperature at a nip portion without having a plurality of temperature sensors and appropriately perform the fixing in a fixing device that rotatingly drives a fixing belt with its laid across a heating roller and a fixing roller, and heatingly fixes a toner image to a recording medium at the nip portion where the fixing roller and a pressure roller face each other via the fixing belt.SOLUTION: A fixing device 30 heatingly fixes a toner image t to a recording medium S at the nip portion where a fixing roller 32 and a pressure roller 34 face each other via a fixing belt 33 heated by a heating roller 31. Before starting the fixing operation, the fixing device rotatingly drives the fixing belt, and measures the temperature of the fixing belt at the nip portion by a temperature sensor 35 provided in the heating roller side. On the basis of the measurement result, control means 40 controls fixing conditions in the fixing device.

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile machine, and a complex machine of these. In particular, an endless fixing belt is rotatively driven across a heating roller and a fixing roller, and the fixing belt is heated by the heating roller, and the fixing roller and the pressure roller are connected via the fixing belt. In an image forming apparatus provided with a fixing device that heat-fixes a toner image on a recording medium at an opposing nip portion, the temperature of the nip portion is appropriately detected before the fixing operation by the fixing device is started, and the fixing operation is performed. From the beginning, the toner image can be heated and fixed on the recording medium under the appropriate conditions by the above-described fixing device.

  2. Description of the Related Art Conventionally, in image forming apparatuses such as copying machines, printers, facsimiles, and composite machines thereof, an endless fixing belt is used as a heating roller as a fixing device that heats and fixes a toner image transferred onto a recording medium. The roller is driven to rotate around the fixing roller, and the fixing belt is heated by the heating roller, and the toner image is heated to the recording medium through the fixing belt at the nip portion where the fixing roller and the pressure roller face each other. A fixing device for fixing is used.

  Here, in the fixing device using the fixing belt as described above, generally, the temperature of the heating roller and the temperature of the fixing belt heated by the heating roller are measured by a temperature sensor, and the heating is performed based on the measurement result. The temperature at which the fixing belt is heated is controlled by a roller.

  Here, in such a fixing device, a fixing belt having a small heat capacity is generally used so that the fixing belt is quickly heated by the heating roller.

  However, when such a fixing belt having a small heat capacity is used, the heated fixing belt is easily cooled, and the toner image is heated to the recording medium at the nip portion where the fixing roller and the pressure roller face each other through the fixing belt. When fixing, if the temperature at the nip part where the fixing roller and the pressure roller face each other is low, the heat of the fixing belt is taken away by the fixing roller and the pressure roller, and the toner image is appropriately heated and fixed on the recording medium. There was a problem that it could not be made.

  Conventionally, as disclosed in Patent Document 1, two temperature sensors are provided so as to detect the temperatures of the heating roller and the fixing roller at the positions of the heating roller and the fixing roller. As disclosed in Patent Document 2, two temperature sensors are provided so as to detect the temperature of the fixing belt at the positions of the heating roller and the fixing roller, respectively, and the temperature sensor further detects the temperature of the pressure roller. As shown in Japanese Patent Application Laid-Open No. 2003-228688, and as disclosed in Patent Document 3, two temperatures are detected so that the temperature of the fixing belt is detected on the upstream side and the downstream side of the nip portion where the fixing roller and the pressure roller face each other. A device in which a temperature sensor is provided has been proposed.

  In these Patent Documents 1 to 3, the heating temperature of the fixing belt by the heating roller is controlled based on the temperature measured by the two or more temperature sensors as described above, and the fixing belt is used. Thus, an appropriate fixing temperature is obtained at the nip portion where the fixing roller and the pressure roller face each other.

  However, as shown in Patent Documents 1 to 3, if a plurality of temperature sensors are provided, the cost is high, and it is necessary to secure a position where each temperature sensor is provided, which increases the size of the apparatus. There was a problem such as.

JP 2005-181875 A JP 2006-178267 A JP 2009-75251 A

  According to the present invention, an endless fixing belt is driven to rotate across a heating roller and a fixing roller, and the fixing belt is heated by the heating roller, and the fixing roller and the pressure roller are passed through the fixing belt. It is an object of the present invention to solve the above-described problems in the case of using a fixing device in which a toner image is heated and fixed on a recording medium at a nip portion opposite to the recording medium.

  That is, according to the present invention, in the image forming apparatus using the fixing device as described above, the temperature at the nip portion where the fixing roller and the pressure roller face each other can be appropriately detected without providing a plurality of temperature sensors. Therefore, it is an object of the present invention to make it possible to heat and fix a toner image on a recording medium with appropriate conditions from the beginning of the fixing operation.

  In the present invention, in order to solve the above-described problems, an endless fixing belt is driven to rotate across a heating roller and a fixing roller, and the fixing belt is heated by the heating roller. In the image forming apparatus provided with a fixing device that heat-fixes the toner image on the recording medium at the nip portion where the fixing roller and the pressure roller face each other via the fixing roller, the temperature of the fixing belt on the heating roller side is detected. A temperature sensor is provided, and before the fixing operation by the fixing device is started, the fixing belt is driven to rotate, and the fixing belt in the nip portion where the fixing roller and the pressure roller face each other is positioned at the position of the temperature sensor. Then, the temperature of the fixing belt at the nip portion is measured, and based on the measurement result, the above fixing device is controlled by the control means. And to control the fixing conditions in the.

  Thus, before starting the fixing operation, the fixing belt is rotationally driven, and the fixing belt in the nip portion where the fixing roller and the pressure roller face each other is guided to the position of the temperature sensor to measure the temperature of the fixing belt in the nip portion. Even without providing a temperature sensor on the fixing roller side, the temperature at the nip portion where the fixing roller and the pressure roller face each other can be appropriately measured by one temperature sensor on the heating roller side.

  Thus, based on the temperature at the nip portion measured by one temperature sensor on the heating roller side, the fixing condition in the fixing device can be appropriately controlled by the control means.

  Here, before starting the fixing operation by the fixing device as described above, the fixing belt is rotationally driven, and the temperature of the fixing belt at the nip portion where the fixing roller and the pressure roller face each other is measured by a temperature sensor. In this case, heating of the fixing belt by the heating roller is started, the rotation direction of the fixing belt is controlled, and the nip portion is detected by the temperature sensor at a position before the fixing belt is heated by the heating roller. The temperature of the fixing belt can be measured. In addition, the fixing belt is rotated and driven without starting the heating of the fixing belt by the heating roller, and the portion of the fixing belt in the nip portion where the fixing roller and the pressure roller face each other is led to the position of the temperature sensor. The temperature of the fixing belt can be measured. In this way, the temperature of the nip portion before the fixing operation by the fixing device is started can be appropriately measured by the above temperature sensor via the fixing belt.

  Further, in controlling the fixing conditions in the fixing device by the control means as described above, for example, the heating conditions of the fixing belt by the heating roller, the speed at which the toner image is heated and fixed on the recording medium, and the fixing roller and the pressure It is possible to control at least one selected from the pressure in the nip portion facing the roller.

  In the present invention, the fixing belt is rotationally driven before the fixing operation by the fixing device is started, and the fixing belt in the nip portion where the fixing roller and the pressure roller face each other is detected, and the temperature of the fixing belt on the heating roller side is detected. Since the temperature of the fixing belt at the nip portion is measured by this temperature sensor after being led to the position of the temperature sensor, the fixing roller and the pressure before starting the fixing operation by one temperature sensor on the heating roller side described above. The temperature of the nip portion facing the roller can be appropriately measured.

  Then, based on the temperature of the nip portion before starting the fixing operation measured in this manner, the above-mentioned control means appropriately controls the fixing conditions in the fixing device, so that the above fixing operation is started from the beginning. The fixing device can heat and fix the toner image on the recording medium under appropriate conditions.

1 is a schematic cross-sectional explanatory diagram of an image forming apparatus according to an embodiment of the present invention. FIG. 3 is a schematic explanatory diagram illustrating a state in which a toner image is fixed on a recording medium by a fixing device in the image forming apparatus according to the embodiment. In the image forming apparatus according to the above-described embodiment, before the fixing operation is started by the fixing device, the fixing belt is rotationally driven in a direction opposite to that during the fixing operation, and fixing is performed at a nip portion where the fixing roller and the pressure roller face each other. It is the schematic explanatory drawing which showed the state which introduce | transduces a belt to the position of a temperature sensor and measures the temperature in a nip part. In the image forming apparatus according to the above-described embodiment, before the fixing operation is started by the fixing device, the fixing belt is rotationally driven in a direction opposite to that during the fixing operation, so that the fixing roller and the pressure roller are opposed to each other at the nip portion. After measuring the temperature of the fixing belt, with the fixing belt heated by a heating roller, the fixing belt is driven to rotate in the same direction as the fixing operation, and the fixing is guided to the position of the temperature sensor through the nip portion. It is the schematic explanatory drawing which showed the state which measures the temperature of a belt. In the image forming apparatus according to the above-described embodiment, using the fixing device of the modified example in which the position of the temperature sensor is changed, before starting the fixing operation, the fixing belt is rotationally driven in the same direction as the fixing operation, FIG. 6 is a schematic explanatory view showing a state in which a fixing belt in a nip portion where a fixing roller and a pressure roller face each other is guided to a temperature sensor position and a temperature in the nip portion is measured.

  Next, an image forming apparatus according to an embodiment of the present invention will be specifically described with reference to the accompanying drawings. Note that the image forming apparatus according to the present invention is not limited to those shown in the following embodiments, and can be implemented with appropriate modifications within a range not changing the gist thereof.

  In the image forming apparatus 1 of this embodiment, as shown in FIG. 1, four imaging cartridges 10A to 10D are mounted therein.

  Here, each of the imaging cartridges 10A to 10D is exposed to the photoconductor 11, the charging device 12 for charging the surface of the photoconductor 11, and the surface of the charged photoconductor 11 according to image information. An exposure device 13 that forms an electrostatic latent image on the surface of the photoconductor 11, a developing device 14 that supplies toner to the electrostatic latent image formed on the surface of the photoconductor 11 to form a toner image, and a photoconductor A cleaning device 15 is provided for removing toner remaining on the surface of the photoconductor 11 after the toner image formed on the surface of the photoconductor 11 is transferred to the intermediate transfer belt 21.

  Further, in the image forming apparatus 1, toners having different colors of black, yellow, magenta, and cyan are accommodated in the developing devices 14 in the imaging cartridges 10A to 10D.

  In this image forming apparatus 1, in each of the imaging cartridges 10 </ b> A to 10 </ b> D, the surface of the photoconductor 11 is charged by the charging device 12, and the surface of each photoconductor 11 thus charged is exposed. The apparatus 13 performs exposure according to the image information to form an electrostatic latent image according to the image information on the surface of each photoconductor 11, and thus the electrostatic latent image formed on the surface of each photoconductor 11. In addition, the respective color toners are supplied from the respective developing devices 14 to form toner images of the respective colors on the surface of the respective photoreceptors 11.

  Next, the toner images of the respective colors formed on the surfaces of the respective photoreceptors 11 in the respective imaging cartridges 10 </ b> A to 10 </ b> D in this way are sequentially transferred to the intermediate transfer belt 21, and the full-color toner image is formed on the intermediate transfer belt 21. A toner image is formed, and toner remaining on the surface of each photoconductor 11 after transfer is removed from the surface of each photoconductor 11 by a cleaning device 15.

  On the other hand, the recording medium S accommodated in the image forming apparatus 1 is fed by the paper feed roller 22, and this recording medium S is placed between the intermediate transfer belt 21 and the transfer roller 24 by the timing roller 23 at an appropriate timing. The full-color toner image formed on the intermediate transfer belt 21 is transferred onto the recording medium S, and the toner remaining on the intermediate transfer belt 21 without being transferred onto the recording medium S is transferred to the second cleaning device 25. Thus, the intermediate transfer belt 21 is removed.

  Then, the recording medium S to which the full-color toner image is transferred as described above is guided to the fixing device 30, and the fixing device 30 fixes the full-color toner image on the recording medium S. Is discharged by a paper discharge roller 27.

  Here, in the fixing device 30 in this embodiment, as shown in FIGS. 1 and 2, an endless fixing is performed between a heating roller 31 provided with a heater 31 a such as a halogen lamp and a fixing roller 32. The belt 33 is bridged and a pressure roller 34 is provided at a position facing the fixing roller 32 via the fixing belt 33, and the fixing belt 33 is connected to the heating roller 31, the fixing roller 32, and the pressure roller 34. It is made to drive rotationally with rotation.

  In the fixing device 30, when the toner image t transferred as described above is fixed on the recording medium S, the heating roller 31 is heated by the heater 31a and the heating roller 31 thus heated is used. The fixing belt 33 is heated by this, and the fixing belt 33 heated in this way is driven to rotate as described above to lead to the nip portion where the fixing roller 33 and the pressure roller 34 face each other, and in this nip portion, the toner image t Is fixed to the recording medium S by heating.

  In the fixing device 30, a temperature sensor 35 for measuring the temperature of the fixing belt 33 is provided in the vicinity of the heating roller 31 on the side where the fixing belt 33 is led from the heating roller 31 to the nip portion. The temperature of the fixing belt 33 measured by 35 is output to the control device 40.

  In this embodiment, before the operation of fixing the toner image t to the recording medium S by the fixing device 30 is started, as shown in FIG. The roller 34 is rotated in the direction opposite to that during the fixing operation, and the fixing belt 33 is rotated in the direction opposite to that during the fixing operation, so that the fixing belt 33 in the nip portion where the fixing roller 32 and the pressure roller 34 face each other is driven. The temperature of the fixing belt 33 guided to the position of the temperature sensor 35 is measured by the temperature sensor 35, and the fixing roller 32 and the pressure before the fixing operation is started by heating the fixing belt 33. The temperature of the nip portion facing the roller 34 is detected.

  Here, as described above, the temperature sensor 35 is provided in the vicinity of the heating roller 31 on the side where the fixing belt 33 is guided from the heating roller 31 to the nip portion, and the fixing belt 33 is rotationally driven in a direction opposite to that during the fixing operation. In this case, even if the fixing belt 33 is heated by the heating roller 31, the portion of the fixing belt 33 in the nip portion is guided to the position of the temperature sensor 35 before being heated by the heating roller 31. Thus, the temperature of the nip portion before the fixing operation is started by heating the fixing belt 33 can be appropriately measured by the temperature sensor 35 described above.

  Then, the temperature of the nip portion measured by the temperature sensor 35 as described above is output to the control device 40. Based on the temperature of the nip portion thus output, the control device 40 causes the heating roller to 31, the temperature at which the fixing belt 33 is heated is set, and then, as shown in FIG. 2, the fixing belt 33 heated in this way is rotated in the direction of the fixing operation, and the fixing belt 33 is heated. The toner image t is guided to the nip portion facing the pressure roller 34, and the toner image t is fixed to the recording medium S in the nip portion.

  Further, before starting the fixing operation as described above, the fixing belt 33 is rotationally driven in a direction opposite to that during the fixing operation, and the temperature at the nip portion is measured by the temperature sensor 35, and then the fixing operation is started. Instead, as shown in FIG. 4, in the state where the fixing belt 33 is heated by the heating roller 31, the fixing belt 33 is rotationally driven in the same direction as in the fixing operation, so that the fixing roller 33 and the pressure roller 34 are driven. The temperature of the fixing belt 33 is measured by the temperature sensor 35 through the nip portion where the fixing belt 33 is opposed, and the temperature of the fixing belt 33 is measured. Based on the temperature difference of the nip portion later, the temperature of the fixing belt 33 heated by the heating roller 31 is set by the control device 40 described above. It is also possible to.

  Further, before the operation of fixing the toner image t onto the recording medium S by the fixing device 30 is started, the heating roller 31 is used to detect the temperature of the nip portion where the fixing roller 32 and the pressure roller 34 face each other. Thus, the fixing belt 33 is not heated, the fixing belt 33 is rotated in the direction of the fixing operation, and the fixing belt 33 at the nip portion where the fixing roller 32 and the pressure roller 34 face each other is moved to the temperature sensor 35. The temperature of the fixing belt 33 thus guided can be measured by the temperature sensor 35.

  Further, in this embodiment, the temperature sensor 35 for measuring the temperature of the fixing belt 33 is provided with the heating roller 31 on the side where the fixing belt 33 is guided from the heating roller 31 to the nip portion where the fixing roller 33 and the pressure roller 34 face each other. As shown in FIG. 5, the temperature sensor 35 is provided near the heating roller 31 on the side where the fixing belt 33 is guided to the heating roller 31 from the nip portion where the fixing roller 33 and the pressure roller 34 face each other. It is also possible to provide in the vicinity.

  When the temperature sensor 35 is provided in the vicinity of the heating roller 31 on the side where the fixing belt 33 is led from the heating roller 31 from the nip portion where the fixing roller 33 and the pressure roller 34 face each other, the fixing belt 33 is provided. The fixing belt 33 is rotated in the same direction as in the fixing operation, and the fixing belt 33 in the nip portion where the fixing roller 32 and the pressure roller 34 face each other is guided to the position of the temperature sensor 35. Is measured by the temperature sensor 35, and before the fixing operation is started, the temperature of the nip portion where the fixing roller 32 and the pressure roller 34 face each other is detected.

  In this way, even if the fixing belt 33 is heated by the heating roller 31, the portion of the fixing belt 33 in the nip portion is guided to the position of the temperature sensor 35 before being heated by the heating roller 31. Thus, the temperature of the nip portion before starting the fixing operation can be appropriately measured by the temperature sensor 35.

  In the above embodiment, before the operation of fixing the toner image t onto the recording medium S by the fixing device 30 is started, the temperature of the nip portion where the fixing roller 32 and the pressure roller 34 face each other is detected. Based on this, the temperature of the fixing belt 33 to be heated by the heating roller 31 is set by the control device 40, but the heating roller 31, the fixing roller 32 and the pressure roller 34 are set by the control device 40. The rotational speed is changed to control the fixing speed at which the toner image t is heated and fixed on the recording medium S, or the pressure at the nip portion where the fixing roller 32 and the pressure roller 34 face each other is controlled. You can also.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 10A-10D Imaging cartridge 11 Photoconductor 12 Charging apparatus 13 Exposure apparatus 14 Developing apparatus 15 Cleaning apparatus 21 Cleaning apparatus 21 Intermediate transfer belt 22 Paper feed roller 23 Timing roller 24 Transfer roller 25 Second cleaning apparatus 27 Paper discharge roller 30 Fixing apparatus 31 Heating roller 31a Heater 32 Fixing roller 33 Fixing belt 34 Pressure roller 35 Temperature sensor 40 Control device S Recording medium t Toner image

Claims (4)

  An endless fixing belt is driven to rotate across a heating roller and a fixing roller, and the fixing belt is heated by the heating roller, and the fixing roller and the pressure roller face each other through the fixing belt. In an image forming apparatus including a fixing device that heat-fixes a toner image on a recording medium at a nip portion, a temperature sensor that detects the temperature of the fixing belt on the heating roller side is provided, and a fixing operation by the fixing device is started. Before the fixing belt is rotated, the fixing belt in the nip portion where the fixing roller and the pressure roller face each other is guided to the position of the temperature sensor to measure the temperature of the fixing belt in the nip portion. An image shape characterized by controlling a fixing condition in the fixing device by a control means based on a measurement result. Apparatus.   2. The image forming apparatus according to claim 1, wherein when the fixing belt is rotationally driven before the fixing operation by the fixing device is started, heating of the fixing belt by the heating roller is started, the rotation direction of the fixing belt is controlled, and the nip is controlled. An image forming apparatus, wherein the temperature of the fixing belt at the nip portion is measured by the temperature sensor at a position before the fixing belt at the portion is heated by the heating roller.   2. The image forming apparatus according to claim 1, wherein before the fixing operation by the fixing device is started, the fixing belt and the pressure roller are rotated by rotating the fixing belt without starting the heating of the fixing belt by the heating roller. An image forming apparatus characterized in that a portion of a fixing belt in an opposing nip portion is guided to a position of a temperature sensor.   4. The image forming apparatus according to claim 1, wherein when the fixing unit is controlled by the control unit, the heating condition of the fixing belt by the heating roller and a toner image are recorded. An image forming apparatus that controls at least one selected from a speed at which a medium is heated and fixed and a pressure at a nip portion where a fixing roller and a pressure roller face each other.

Images