JP2008089973A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which prevents a pressure roller from idling in fixation conveyance of a recording material due to dew condensation, makes a fixing unit compact, and prevents image deterioration due to a slip. <P>SOLUTION: The image forming apparatus is characterized in that when the size of a recording material 102 input by a user through a console panel (not illustrated) etc., a control unit 120 switches the control timing of conveyance of the recording material 102 according to the width of the recording material 102 to perform slip prevention control. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus having a fixing device as a heating device for heating a recording material.

  Conventionally, an image forming apparatus includes a photosensitive drum, a charging unit, an exposure unit, a developing unit, a transfer unit, a fixing unit, and the like, and can form an image on a recording material by a predetermined image forming process. Yes. Here, the photosensitive drum is an electrostatic latent image carrier that forms an electrostatic latent image on the surface, the charging unit is a unit that uniformly charges the photosensitive drum, and the exposure unit is charged by the charging unit. This is means for exposing the surface of the photosensitive drum to form an electrostatic latent image. Further, the developing device develops the electrostatic latent image on the photosensitive drum with toner as a developer to make it visible, and the transfer means transfers the toner image on the photosensitive drum onto the recording material. The fixing device heats and fixes the toner on the recording material.

  The fixing device as a heating device for heating the recording material includes, for example, a fixing roller having a configuration in which an elastic layer and a release layer are provided on the outer periphery of a metal roller, and a heater that is a heating member disposed in the fixing roller. The heat roller comprised by this is provided. The heat roller has a substantially long cylindrical shape and is rotatably disposed on the apparatus main body. At the same time, the fixing roller is heated by a heater in the heat roller to heat the surface of the fixing roller to a fixing temperature (corresponding to a target temperature) necessary for fixing, and the recording material can be heated by the fixing roller heated by the heater. It has become. In addition, a fixing device is configured by pressing a pressure roller rotatably disposed on the heat roller. Then, by passing the recording material on which the toner image is transferred to the pressure contact portion between the heat roller and the pressure roller, the toner on the recording material can be heated and pressurized to melt and fix the toner on the recording material. It is like that.

  The heater of the fixing device is turned on / off by a drive signal from a temperature control means in a control means provided in the image forming apparatus so that the heater temperature can be controlled to a predetermined temperature. A thermistor is disposed on the surface of the heat roller as temperature detecting means for detecting the temperature of the heat roller. The thermistor transmits a resistance value that changes according to the temperature change of the heat roller to the control means as a detection signal, and the temperature detection means in the control means controls the heater by the detection signal from the thermistor to control the heater temperature to a predetermined temperature. To do. As a result, the heat roller can be controlled to a temperature necessary for fixing. In this type of fixing device that heats a roller with a heater, since the heat capacity of the roller is generally large and it takes time until the roller reaches a predetermined temperature after the heater is heated, the roller is turned on immediately after the image forming apparatus is turned on. The temperature is controlled by heating to a predetermined temperature.

  Recently, in order to realize power saving during standby and shorten the time from power-on to image output, the following film heating type fixing device has been proposed (for example, see Patent Document 1). . This fixing device has a heater unit composed of a heater, which is a fixed and supported heating member, a heat-resistant and small heat capacity film disposed opposite to the heater, and a recording material in close contact with the surface of the heater unit film. A pressure roller as a pressure member. Then, the heater heats the toner on the recording material through a film having a small heat capacity, so that the toner image formed on the surface of the recording material is heated and fixed.

  In the film heating method using the above film, the heater heats the recording material through a film having a small heat capacity. For this reason, by raising the heater to the temperature required for fixing instantaneously, the heating amount required for fixing can be applied to the recording material even if power is supplied to the heater for the first time by a print start command. ing. Therefore, there is no need to adjust the temperature immediately after turning on the power, which is performed by a roller type fixing device, which is advantageous for reducing the power consumption of the apparatus.

  Further, the fixing device detects the presence or absence of the fixing device and the failure of the heater or the thermistor using a detection signal from the thermistor. The detection of the presence or absence of the fixing device or the failure of the thermistor or the like is performed after power is supplied to the heater. For example, in the film heating method using the above-described film, power is supplied to the heater in response to a print start command, and then the detection signal is transmitted from the thermistor to the temperature control means.

In an image forming apparatus using a film fixing type fixing device, electric power is supplied to the heater for a predetermined time or a predetermined temperature to the lubricant applied between the film and the heater before rotating the fixing member. As a result, the temperature is increased to a temperature having a function as a lubricant, and then the temperature of each part of the fixing unit is adjusted to the predetermined temperature that can be fixed while rotating the fixing member to adjust the temperature to a predetermined temperature. ing.
JP 07-199703 A

  However, in the image forming apparatus using the conventional film fixing type fixing device, the heat capacity is small, so that the temperature rises quickly.

  As described above, in an image forming apparatus using a film fixing type fixing device, rotation of a film member and conveyance of a recording material are performed by rotation of a pressure roller, and the film member is driven by the pressure roller. It has become.

  Since the film member has a thin structure, it can follow the temperature rise of the heater, but the pressure roller has a heat capacity due to its structure.

  For this reason, when the printing operation is performed from a state in which the fixing device is not warmed and when the recording material has a large amount of water, the amount of water released as water vapor from the recording material warmed by the heater increases. Then, the moisture that has not been discharged due to the exhaust or the like adheres to the surface of the pressure roller that is not in a high temperature state and is condensed.

  In the above-described state, moisture is interposed between the pressure roller and the recording material, and between the pressure roller and the film member, and the friction force that constitutes the force for conveying the recording material and the force for rotating the film is constituted. The friction coefficient μ to be reduced is significantly reduced.

  Due to this decrease, the recording material cannot be transported, and the pressure roller may cause a slip in which the recording roller instantaneously idles, which may deteriorate the image quality.

  Conventionally, to solve this problem, a means for transmitting a driving force to the film is separately provided, or the fixing device is enlarged in order to obtain a large portion that receives heat from the heater without using a recording material, and as a result, an image forming apparatus. There is a problem that it is necessary to increase the size of the device, which is expensive.

  The present invention has been made paying attention to the above points, and prevents idling of the pressure roller in the fixing conveyance of the recording material due to condensation on the pressure roller, reduces the size of the fixing device, and causes image degradation due to slip. An object of the present invention is to provide an image forming apparatus for preventing the above-described problem.

In order to solve the above problem, according to the present invention as defined in claim 1,
Means for detecting the size of the recording material are provided, and means for switching the control timing relating to the conveyance of the recording material according to the size of the recording material in the width direction relative to the conveyance direction is provided. As a result, it is possible to prevent idling of the pressure roller during fixing conveyance of the recording material due to condensation on the pressure roller.

According to the present invention as set forth in claim 2,
Means for detecting the material and surface property of the recording material are provided, and means for switching the control timing relating to the conveyance of the recording material according to the material and surface property of the recording material in the transport direction is provided. As a result, it is possible to prevent idling of the pressure roller during fixing conveyance of the recording material due to condensation on the pressure roller.

Furthermore, according to the present invention as set forth in claim 3,
Means for detecting the size of the recording material are provided, and means for switching the control timing relating to the conveyance of the recording material according to the size of the recording material in the width direction relative to the conveyance direction is provided. Furthermore, it has means for detecting the material and surface property of the recording material, and switches the control timing related to the conveyance of the recording material or the predetermined temperature of the temperature control means of the fixing device according to the material and surface property of the recording material in the conveying direction Means are provided. As a result, it is possible to prevent idling of the pressure roller during fixing conveyance of the recording material due to condensation on the pressure roller.

  That is, the technical contents of the present invention can solve the above-described problems by including the following configuration.

  (1) A fixing device that has a rotating member and a heating member that are in contact with the recording material and is rotatably arranged and heats the recording material by the heating member, and detects the temperature of the heating member or the vicinity of the heating member. And a temperature control means for controlling the heating temperature of the heating member so as to keep the temperature of the heating member or the vicinity of the heating member at a target temperature by a detection signal from the temperature detection means. In the apparatus, means for detecting the size of the recording material, and means for switching the control timing of conveyance of the recording material according to the size in the width direction of the recording material detected by the means for detecting the size of the recording material An image forming apparatus comprising:

  (2) A fixing device that has a rotating member and a heating member that are in contact with the recording material and is rotatably arranged to heat the recording material by the heating member, and detects the temperature of the heating member or the vicinity of the heating member. And a temperature control means for controlling the heating temperature of the heating member so as to keep the temperature of the heating member or the vicinity of the heating member at a target temperature by a detection signal from the temperature detection means. In the apparatus, the recording material is conveyed according to the material and surface property detected by the recording material and surface property, and the recording material quality and surface property detected by the recording material material and surface property. An image forming apparatus comprising: means for switching control timing.

  (3) A fixing device that has a rotating member and a heating member arranged in contact with the recording material and is rotatable, and detects the temperature of the heating member or the vicinity of the heating member. And a temperature control means for controlling the heating temperature of the heating member so as to keep the temperature of the heating member or the vicinity of the heating member at a target temperature by a detection signal from the temperature detection means. In the apparatus, means for detecting the size of the recording material, and means for switching the control timing of conveyance of the recording material according to the size in the width direction of the recording material detected by the means for detecting the size of the recording material , Means for detecting the material and surface property of the recording material, and material and surface property of the recording material detected by the means for detecting the material and surface property of the recording material In response, the control timing of the conveyance of the recording material, or image forming apparatus characterized by comprising a means for switching the target temperature of the temperature control means.

  According to the present invention, by changing the conveyance control of the recording material according to the size in the width direction of the recording material, slippage due to condensation of the pressure roller is prevented, and a narrow recording material in which no slip occurs is Processing can be performed without reducing the throughput of the printer.

  In addition, by changing the conveyance control of the recording material according to the material of the recording material, slip caused by condensation of the pressure roller can be prevented, and the recording material of a material that does not generate slip can be processed without reducing the throughput of the printer. It becomes possible to do.

  For this reason, it can be realized without increasing the heating device, the heater and the pressure roller, and a small and inexpensive heating device and image forming apparatus can be provided.

  Further, it is possible to carry out a combination of the first and second embodiments described later, and the prevention of the occurrence of slip can be expected to improve reliability.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to examples.

(First embodiment)
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  First, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a schematic sectional view of a laser printer as an example of the image forming apparatus of this embodiment. A laser printer (hereinafter referred to as a main body) 101 includes a photosensitive drum 108, a charging unit (not shown), an image data conversion unit 105, a developing device, a transfer roller 110, a fixing device 111, a control device 120, and the like. Here, the photosensitive drum 108 corresponds to an electrostatic latent image carrier that forms an electrostatic latent image on the surface, and the charging unit is a unit that uniformly charges the photosensitive drum 108. The image data converter 105 corresponds to an exposure unit that exposes the surface of the photosensitive drum 108 charged by the charging unit to form an electrostatic latent image. Further, the developing device has a developing sleeve 109 that develops the electrostatic latent image on the photosensitive drum 108 with a toner as a developer to make a visible image. The transfer roller 110 is a transfer unit that transfers the toner image on the photosensitive drum 108 onto the recording material 102, the fixing device 111 is provided with a heating member to heat the recording material 102, and the control device 120 is an image. Control each step of formation. The main body 101 is configured by these and can form an image on the recording material 102 by a predetermined image forming process.

  FIG. 2 is a schematic sectional view showing the heater unit 112 and the pressure roller 113 of the fixing device 111. As shown in FIG. 2, the fixing device 111 for fixing the toner on the recording material 102 includes a heater unit 112 having a heater 150 as a heating member and a film 151 disposed to face the heater 150. In addition, a pressure roller 113 is provided as a pressure member that is pressed in the direction of the heater 150 of the heater unit 112 by a pressure unit (not shown). Then, by passing the recording material 102 through the facing portion between the heater unit 112 and the pressure roller 113, the heater 150 can heat the toner on the recording material 102 via the film 151 of the heater unit 112. ing.

  In the heater unit 112, for example, the surface of the heating element of the heater 150 is disposed on the conveyance side of the recording material 102. A film 151 formed in a substantially cylindrical shape using a member having a heat resistance and a small heat capacity is rotatably provided on the outer periphery of the film guide 152 that holds the heater 150. At the same time, the thermistor 114 as temperature detecting means for detecting the temperature of the heater 150 is provided on the surface of the heater 150 opposite to the film 151 side.

  Further, the pressure roller 113 pressed against the heater unit 112 has, for example, silicon rubber as an elastic layer on the outer periphery of the core metal and is rotatably disposed. A driving unit 161 is connected to the rotation shaft of the pressure roller 113 so that the pressure roller 113 can rotate in a predetermined direction, and is fixed as a rotating member that is in contact with the recording material 102 and is rotatably disposed. It is arranged in the vessel 111. The driving means 161 for rotating the pressure roller 113 is operated by a drive signal from a drive control unit (not shown) provided in the control device 120 and can rotate the pressure roller 113. .

  The drive unit 161 is driven by a drive signal from the control device 120, and the pressure roller 113 rotates in a predetermined direction. Then, following the rotation of the pressure roller 113, the film 151 of the heater unit 112 is in close contact with the surface of the heating element of the heater 150 and rotates around the film guide 152. Then, the recording material 102 is passed between the film 151 rotated in a predetermined direction and the pressure roller 113, and the heater 150 heats and presses the toner on the recording material 102 through the film 151 to melt and fix it. Can be done. In addition, the film 151 of the heater unit 112 is driven to rotate as the pressure roller 113 is rotated by the driving unit 161.

  In addition, the heater 150 of the heater unit 112 is controlled by the signal from the temperature control unit 121 as temperature control means for controlling the temperature of the heater provided in the control device 120. Yes.

  A thermistor 114 that is provided in the heater 150 and detects the surface temperature of the heater 150 is connected to the control device 120. A resistance value, which is a temperature detection signal of the thermistor 114, is input to the control device 120 so that the temperature of the heater 150 is detected by the control device 120. The control device 120 that has received the temperature detection signal from the thermistor 114 turns the heater 150 on and off by the temperature control unit 121 based on the temperature detection signal. As a result, the heating drive is controlled to control the surface temperature of the heater 150 to a predetermined temperature.

  Also, in the control device 120 of the main body 101, whether or not the temperature based on the detection signal input from the thermistor 114 to the control device 120 when the heater driving circuit of the image forming apparatus fails is higher than a predetermined temperature set in advance. A determination means 130 for determining is provided. At the same time, the determination unit 130 and the thermistor 114 are connected, and a temperature detection signal of the thermistor 114 is input to the determination unit 130.

  Here, the predetermined temperature set in the determination unit 130 is a temperature based on a detection signal transmitted from the thermistor 114 when the temperature of the heater 150 is equal to or higher than the temperature at which the toner can be fixed to the recording material 102. In order to reliably detect a failure when the heater drive circuit fails, the predetermined temperature set in the determination unit 130 is set slightly higher than the temperature at which the toner can be fixed on the recording paper. You may do it.

  Furthermore, the control device 120 is provided with a failure detection means 140. The failure detection unit 140 operates when the determination unit 130 determines that the temperature based on the detection signal of the thermistor 114 is higher than the set predetermined temperature. The failure detection unit 140 opens a relay (not shown) to the heater 150 together with a failure notification when receiving a signal when the temperature based on the detection signal of the thermistor 114 is higher than a predetermined temperature set in advance from the determination unit 130. Can be turned off.

  Due to the heat conduction to the thermistor 114 and the thermal response (heat capacity) of the thermistor 114, there is a time lag and delay between the actual temperature of the heat generating part and the detected temperature.

  In a state where the fixing motor 161 for rotating the pressure roller 113 is driven, the temperatures in the pressure roller 113 and the fixing device 111 are transmitted to each part, the temperature is slowly increased, and the heat to the thermistor 114 is also sufficiently transmitted. .

  Further, when the pressure roller 113 is not driven by the fixing motor 161, heat is not transmitted to each part in the fixing device 111, and only the heat generating part and the vicinity of the heat generating part rapidly increase in temperature.

  The operation of the laser printer having the above configuration will be described. In response to a recording operation start command from a computer (not shown) connected to the main body 101, the heater 150 is activated by a drive signal from the temperature control unit 121 and the heater 150 of the fixing device 111 is heated. The temperature of the heater 150 is monitored by the thermistor 114 in contact with the heater 150.

  After the temperature of the heater 150 reaches a predetermined temperature, only one sheet of the recording material 102 is fed to the conveyance path via the conveyance roller 104 by the paper feed roller 103, and the skew of the recording material 102 is removed by the registration roller 105. To do. Image data is sent from the computer to the image data converter 106, and the laser in the image data converter 106 is repeatedly turned on and off in synchronization with this data.

  This laser beam is reflected by the mirror 107 and guided to the photosensitive drum 108. Then, a latent image is formed on the photosensitive drum 108, the latent image formed on the photosensitive drum 108 is developed by the developing sleeve 109 to be visualized, and the image on the photosensitive drum 108 is recorded on the recording material 102 by the transfer roller 110. Transcript to. Thereafter, the toner on the recording material 102 is fixed by the fixing device 111. The recording material 102 is discharged from a discharge port 116 by a discharge roller 115. In the main body 101 having the above configuration, the temperature of the fixing device 111 is constantly monitored.

  The image forming apparatus has an input device from a user such as an operation panel (not shown), and the input setting information is transmitted to the control device 120 as a command or level signal by a known communication means (not shown). The control device 120 can determine the size of the recording material 102 based on the setting information input from the operation panel.

  Here, it demonstrates using FIG. FIG. 3A is a side view showing the film 151, the pressure roller 113, and the recording material 102 according to this embodiment, and FIG. 3A illustrates how heat is transferred when the recording material Lsl is wide. The figure, (a-2) is a graph showing the temperature distribution corresponding to (a-1). 3B is a side view showing the film 151, the pressure roller 113, and the recording material 102 according to the present embodiment, and FIG. 3B-1 shows how heat is transmitted when the recording material Lss is narrow. The figure to explain, (b-2) is a graph which shows the temperature distribution corresponding to (b-1).

  As shown in FIGS. 3A and 3B, the way in which heat is transferred from the heater 150 to the pressure roller 113 (arrows in the figure) differs depending on the size of the recording material 102. In the case of the recording material Lsl having a large size in the width direction, that is, a wide width, the path through which heat is transmitted to the pressure roller 113 is mostly film 151 → recording material Lsl → pressure roller 113. On the other hand, the path in the case of the recording material Lss having a small size in the width direction, that is, a narrow width, has many portions where the film 151 → the pressure roller 113.

  From the above, in the case of the recording material Lss having a narrow width, the portion where the pressure roller 113 is warmed becomes large ((b-2) in FIG. 3B). The heated portion of the pressure roller 113 does not condense, and the condensation is resolved early. As a result, slip due to idling of the pressure roller 113 does not occur, and image degradation does not occur.

  As an example of slip prevention, in the case of a wide recording material Lsl, before the recording material Lsl enters the fixing device 111, the pressure roller 113 is sufficiently warmed to prevent condensation. Further, in order to solve the dew condensation state at an early stage, it is necessary to control the interval at which the recording material Lsl is inserted into the fixing device 111 and to keep the pressure roller 113 at a temperature at which dew condensation does not occur (a temperature at which no water droplets are formed).

  However, the narrow recording material Lss does not cause slip even if the above processing is not performed.

  From the above, it is determined from the size of the recording material 102 in the width direction whether processing for preventing slipping of the pressure roller 113 is performed. As a result, it becomes possible to provide a fixing device in which slip does not occur without reducing the throughput of the narrow recording material Lss and an image forming apparatus using the same. In FIG. 3, Lf represents the maximum width in which the recording material 102 can pass.

  FIG. 4 is a flowchart illustrating the slip prevention control according to the present embodiment. Hereinafter, a description will be given using the flowchart of FIG.

  The process starts immediately after printing on the main body 101 is determined.

  It is determined whether or not the size in the width direction of the recording material 102 for which printing has been determined is greater than or equal to the paper width L where slipping occurs (step S101). When the paper width is equal to or greater than the paper width L and it is determined that the print is continuous (step S102), slip prevention control (for example, extension between papers) is performed (step S103). If the size of the recording material 102 in the width direction is narrower than the paper width L (No in step S101), or is not less than the paper width L but not continuous printing (No in step S102), normal control is performed (step S104). If it is not determined that printing will continue (step S105), this process ends. Note that the control unit 120 can extend the sheet interval by switching the control timing of the conveyance of the recording material 102.

  As described above, the size of the recording material 102 in the width direction prevents slipping due to condensation of the pressure roller 113, and the narrow recording material Lss that does not generate slip can be processed without reducing the throughput of the printer. Become. Therefore, the fixing device, the heater, and the pressure roller can be realized without increasing the size, and a small and inexpensive fixing device and image forming apparatus can be provided.

  In the description of the above embodiment, the size information of the recording material 102 is input from the input device. However, it is of course possible to have size detection means and use the detection result. Further, processing based on information from a host computer (PC) such as a printer driver is also conceivable.

  In each of the above embodiments, the slip prevention control in the fixing unit of the laser printer has been described. However, the present invention is not limited to the laser printer. In other words, if a heating member is provided and the toner on the recording material 102 is heated and fixed by the heating member, the slip prevention is applied to electrophotographic printers such as LED printers, liquid crystal shutter printers, copying machines, and fax machines. Control can be performed.

(Second embodiment)
A second embodiment will be described with reference to FIGS. FIG. 5 is a side view showing the film 151, the pressure roller 113, and the recording material 102 according to this embodiment. Here, Lsl represents the size of the recording material 102 in the width direction, and Lf represents the maximum width in which the recording material 102 can pass.

  The difference from the first embodiment is based on the information inputted by the input device about the material and surface property (type) of the recording material 102.

  The recording material 102 used in the printer may be thick or thin, but the surface property varies depending on the type. Some have a rough surface or some have a smooth surface, and the friction coefficient may vary greatly.

  A recording material that is said to have good surface properties has few irregularities on the surface of the recording material and is often fine. In this case, when the pressure roller 113 is condensed, the tire is in the same state as a worn tire and is in a slippery state with a low friction coefficient. It is this category that is generally referred to as high-quality paper in the Japanese market.

  On the other hand, a recording material with poor visibility has irregularities like a winter tire, and a friction coefficient is ensured. It is a medium quality paper or a coarse recording material. In the case of a recording material of this material, the condensed water does not lose contact between the pressure roller 113 and the recording material by entering the gaps or recesses of the recording material, and the frictional force is ensured and slipping occurs. do not do.

  FIG. 6 is a flowchart illustrating the slip prevention control according to the present embodiment. Hereinafter, a description will be given using the flowchart of FIG.

  The process starts immediately after printing on the main body 101 is determined.

  It is determined whether or not the recording material 102 for which printing has been determined is a material that can cause a slip (step S201). In the case of a material that can occur, when it is determined that the print is continuous (step S202), slip prevention control (for example, extension between sheets) is performed (step S203). If the slip material of the recording material 102 does not match the generated material (No in step S201), or if the recording material 102 matches the generated material but is not a continuous print (No in step S202), normal control is performed (step S204). ). If it is not determined that printing will continue (step S205), this process ends.

  As described above, the material of the recording material 102 prevents slipping due to condensation of the pressure roller 113, and the recording material of a material that does not generate slip can be processed without reducing the throughput of the printer. Therefore, the fixing device, the heater, and the pressure roller can be realized without increasing the size, and a small and inexpensive fixing device and image forming apparatus can be provided.

  In the description of the above embodiment, the material information of the recording material 102 is input from the input device. However, it is of course possible to have the material detection means of the recording material 102 and use the detection result. Further, processing based on information from a host computer (PC) such as a printer driver is also conceivable.

  In each of the above embodiments, the slip prevention control in the fixing unit of the laser printer has been described. However, the present invention is not limited to the laser printer. In other words, if a heating member is provided and the toner on the recording material is heated and fixed by the heating member, anti-slip control is also applied to electrophotographic printers such as LED printers, liquid crystal shutter printers, copying machines, and fax machines. Can be done.

  Further, as the slip prevention control in step S103 in FIG. 4 and step S203 in FIG. 6, in the above-described embodiment, an example in which the control timing of conveyance of the recording material 102 is switched and the interval between sheets is extended is given. In addition, the slip prevention control can be performed by switching the fixing temperature of the temperature controller 121 by the control device 120.

  Furthermore, both the size in the width direction of the recording material 102 and the material and surface property of the recording material 102 can be detected, and slip prevention control can be performed according to the detection result.

1 is a schematic sectional view showing a laser printer of the present invention. 2 is a schematic cross-sectional view showing a heater unit and a pressure roller of a fixing device. FIG. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view showing a film, a pressure roller, and a recording material according to a first embodiment, wherein (a-1) is a diagram for explaining how heat is transferred when a wide recording material is used, and (a-2) is a diagram. It is a graph which shows the temperature distribution corresponding to (a-1). FIG. 2B is a side view showing the film, the pressure roller, and the recording material according to the first embodiment, where FIG. 5B-1 is a diagram for explaining how heat is transmitted when the recording material is narrow, and FIG. It is a graph which shows the temperature distribution corresponding to (b-1). It is a flowchart explaining slip prevention control concerning the 1st example. It is a side view which shows the film, pressurization roller, and recording material which concern on a 2nd Example. It is a flowchart explaining the slip prevention control which concerns on a 2nd Example.

Explanation of symbols

101 Laser Printer Main Body 102 Recording Material 111 Fixing Unit 112 Heater Unit 113 Pressure Roller (Rotating Member)
114 thermistor (temperature detection means)
120 control device (means for switching control timing of conveyance of recording material, means for switching target temperature of temperature control means)
121 Temperature controller (temperature control means)
130 judgment means 150 heater (heating member)
151 film

Claims (3)

A fixing device that has a rotating member and a heating member that are disposed in contact with the recording material and is rotatable, and a temperature detector that detects the temperature of the heating member or the vicinity of the heating member. And a temperature control means for controlling the heating temperature of the heating member so as to keep the temperature of the heating member or the vicinity of the heating member at a target temperature by a detection signal from the temperature detection means.
Means for detecting the size of the recording material;
An image forming apparatus comprising: means for switching control timing of conveyance of the recording material in accordance with the size in the width direction of the recording material detected by the means for detecting the size of the recording material. A fixing device that has a rotating member and a heating member that are disposed in contact with the recording material and is rotatable, and a temperature detector that detects the temperature of the heating member or the vicinity of the heating member. And a temperature control means for controlling the heating temperature of the heating member so as to keep the temperature of the heating member or the vicinity of the heating member at a target temperature by a detection signal from the temperature detection means.
Means for detecting the material and surface properties of the recording material;
An image forming apparatus comprising: means for switching a control timing of conveyance of the recording material according to the material and surface property of the recording material detected by the means for detecting the material and surface property of the recording material. A fixing device that has a rotating member and a heating member that are disposed in contact with the recording material and is rotatable, and a temperature detector that detects the temperature of the heating member or the vicinity of the heating member. And a temperature control means for controlling the heating temperature of the heating member so as to keep the temperature of the heating member or the vicinity of the heating member at a target temperature by a detection signal from the temperature detection means.
Means for detecting the size of the recording material;
Means for switching the control timing of conveyance of the recording material according to the size in the width direction of the recording material detected by the means for detecting the size of the recording material;
Means for detecting the material and surface properties of the recording material;
Means for switching the recording material conveyance control timing or the target temperature of the temperature control means in accordance with the material and surface quality of the recording material detected by the means for detecting the material and surface quality of the recording material An image forming apparatus comprising:

Images