JP2006039049A - Fixing unit, image forming apparatus using the same, and control method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing unit which makes a temperature distribution approximately uniform to suppress temperature ripple without rotating a heat pipe, and also to provide an image forming apparatus which forms an image by using the fixing unit, and a control method thereof. <P>SOLUTION: The fixing unit is provided with; a pressure roller 120; a heat roller 116 including a cylindrical member 201 rotated in contact with the pressure roller 120, a heater 211 becoming a heat source in the cylindrical member 201 while holding a relative position to the pressure roller 120, and a heat pipe 207 for transmitting heat from the heater 211; and temperature sensors for detecting temperatures of the heat pipe 207 and the heater 211 respectively. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fixing device used in an image forming apparatus using electrophotographic process technology, an image forming apparatus thereof, and a control method thereof.

  2. Description of the Related Art Conventionally, in an image forming apparatus using an electrophotographic process, a recording sheet on which a toner image is transferred is heated and fixed by a fixing device to form an image. The fixing device includes a pressing roller that presses the sheet, and a heating roller that rotates in contact with the pressing roller. In a printer equipped with such a fixing device, when continuous printing is performed on narrow and narrow recording paper, the temperature distribution in the fixing device is uneven in the paper width direction, and the temperature of the non-sheet passing region where the recording paper does not contact is generated. There was a risk of damaging the pressure roller made of an elastic material. For this reason, control such as slowing down the printing speed has been performed.

  In recent years, along with the cost reduction of heat pipes, in order to make the temperature distribution in the fixing device uniform, the heat pipe is used for the heat fixing part, so that the pressure roller is damaged without reducing the printing speed. Proposals related to printer devices that can be prevented have been made as follows.

  Patent Documents 1 and 2 propose a configuration in which a heat pipe is used as a heat roller to make the temperature in the paper width direction uniform, and heat is input from the end of the heat roller.

  Further, Patent Document 3 proposes a configuration in which a temperature rise characteristic by a heater is improved by using a heat pipe for the heat roller and further forming an electric heating element (heater) in the heat pipe.

Furthermore, Patent Document 4 proposes a configuration in which a plurality of thermistor resistance heaters are arranged in the paper width direction using a tubular film to improve the temperature rise performance of the heater.
Japanese Patent Laid-Open No. 3-139684 Japanese Patent Registration No. 0273453 JP 2002-304076 A JP-A-8-137305

Thus, according to the prior art, the heat uniformity is achieved by using a heat pipe for the heating roller (heat roller), and the temperature rise characteristic of the heat roller is improved by devising the heat input method. ing. However, in order to use a heat pipe for the heat roller, it is necessary to rotate the heat pipe itself, and there are the following problems.
(1) A heat pipe composed of a hollow, thin, and highly conductive cylinder is difficult to achieve uniformity, axial accuracy, and strength of the entire surface as a rotating body.
(2) It is difficult to attach the drive gear for rotation directly to the heat pipe in terms of heat and accuracy.
(3) It is difficult to detect the temperature of the rotating heat pipe, and even if the heat pipe is devised to improve the temperature rise performance, the response characteristics for temperature detection are discontinuous.
(4) By covering the outer periphery of the heat pipe with a metal outer cylinder, if the measures (1) to (3) are taken as countermeasures, the thermal resistance to the paper increases, and the temperature rise characteristic of the heat fixing device decreases. To do.
(5) There is a possibility that a dry-out phenomenon of hydraulic fluid may occur.

  In order to overcome these problems, the structure of the fixing device becomes complicated, resulting in an increase in cost.

Moreover, in the conventional example using the cylindrical film of patent document 4,
(A) Since a plurality of heating elements are required, the temperature distribution in the paper width direction varies due to variations in the characteristics of the individual thermistors, and fixing unevenness occurs.
(B) The heat from the heating element is transmitted to the cylindrical film through the insulating film, the heat pipe, and the metal member for attachment. Furthermore, since temperature detection is also used as a heating element, the feedback system is twice that of the heating element and the delay in temperature control response is large. Such a delay in temperature control response is difficult to cope with various types of recording paper such as thin paper, thick paper, and OHT sheet.

  The present invention has been made in view of the above problems, and a feature of the present invention is that a fixing device capable of suppressing temperature ripple by making the temperature distribution substantially uniform without rotating the heat pipe, and the fixing device. An object of the present invention is to provide an image forming apparatus that uses it to form an image and a control method therefor.

A fixing device according to an aspect of the present invention has the following configuration. That is,
A pressure roller;
A cylindrical member that rotates in contact with the pressure roller, and a heater serving as a heat source and conducting heat from the heater in a state where the relative position with respect to the pressure roller is held inside the cylindrical member. A heating roller comprising a heat pipe;
A temperature sensor for detecting the temperature of each of the heat pipe and the heater;
It is characterized by having.

An image forming apparatus according to an aspect of the present invention has the following configuration. That is,
An image forming apparatus for fixing an image transferred to a recording medium by an electrophotographic process to form an image,
A fixing device according to any one of claims 1 to 3,
Heater driving means for energizing the heater to drive heat,
Control means for controlling the heater driving means based on temperature information from the temperature sensor to control the fixing device.

An image forming apparatus control method according to an aspect of the present invention includes the following steps. That is,
A control method for an image forming apparatus, comprising the fixing device according to claim 1, and fixing an image transferred to a recording medium by an electrophotographic process to form an image.
A heater driving step of energizing the heater and driving the heat generation;
A control step of controlling the heater based on temperature information of the heater pipe detected by the temperature sensor when the heater is driven in the heater driving step.

  According to the present invention, it is possible to provide a fixing device capable of suppressing temperature ripple by making the temperature distribution substantially uniform.

  Further, according to the present invention, it is possible to perform image formation in which the temperature distribution is made substantially uniform and the temperature ripple is suppressed without reducing the image formation speed.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[Embodiment 1]
FIG. 1 is a block diagram showing a schematic configuration of a laser beam printer (LBP) which is an example of an image forming apparatus according to an embodiment of the present invention.

  In FIG. 1, reference numeral 101 denotes a laser beam printer (LBP) 100 using an electrophotographic process. The LBP 101 performs a printing operation according to image data transmitted from the host computer 102 via the interface 103. The command and data transmitted from the host computer 102 are analyzed by the image processing controller 104 to generate image data for printing. This image data is developed into a bitmap and input to the engine unit 105 via the communication line 123. The engine unit 105 includes a low-voltage power source that receives an AC voltage 115 from a commercial power source 122 and converts it into a DC voltage, a CPU that controls the operation of the entire printer 101, a high-voltage power source necessary for an electrophotographic process, and a motor. And solenoid actuator drive, various sensors, etc. The engine unit 105 includes a CPU 180 such as a microprocessor, a ROM 181 that stores control programs executed by the CPU 180 and various data, a RAM 182 that temporarily stores various data during control operations by the CPU 180, and instructions from the CPU 180. A timer 183 for measuring time and notifying the CPU 180 is provided.

  A polygon laser scanner 108 is mounted with a semiconductor laser, a mirror rotating unit, and a photodiode for generating a horizontal synchronizing signal of the laser. The engine unit 105 drives the semiconductor laser on and off according to the image data developed by the image processing controller 104 to generate laser light, and reflects the laser light by a rotating mirror, thereby producing an electrophotographic process. The photosensitive drum of the unit 109 is scanned to form an electrostatic image on the drum. A toner image obtained by developing the electrostatic image on the photosensitive drum thus formed with toner is formed, and the toner image is transferred and recorded on the paper 114 fed by the rotation of the paper feed roller 112.

  Reference numeral 110 denotes a heat fixing unit that passes the paper 114 on which the toner image is transferred between the pressure roller 120 and the heater unit 116, thereby fixing the toner image on the paper with pressure and heat. Here, as will be described later, one of the thermistors 117 and 118 is for detecting the temperature of the heater section 116, and the other is for monitoring the temperature of the heat pipe. The engine unit 105 controls the power supply to the heat fixing unit 110 to be turned on / off by a heater power switch unit including a triac 106 and a photo triac according to temperature information from the thermistors 117 and 118. When the temperature detected by the thermistors 117 and 118 is determined to be an abnormal value, the relay 107 cuts off the power supply to the heater unit 116 by a control signal from the engine unit 105. Reference numeral 121 denotes a thermal fuse for cutting off the current supply to the heater unit 116 when an abnormal current flows.

  Reference numeral 111 denotes a paper sensor for detecting that the leading edge of the paper 114 has reached the vicinity of the transfer position. Reference numeral 119 denotes that the paper heated and fixed by the heat fixing unit 110 is discharged from the fixing unit 110. It is a sensor for detecting.

  FIG. 2 is a cross-sectional view for explaining a more detailed structure of the heat fixing device 110, and portions common to FIG. 1 are denoted by the same symbols.

  The toner 230 is transferred onto the paper 114. The transferred toner passes through the heat fixing device 110 and is fixed to the paper 114 by pressure and heat as indicated by reference numeral 231. The pressure roller 120 is configured by forming a porous layer made of foamed rubber or the like on a shaft 214 made of a good heat conductive metal such as aluminum, and is rotated by a motor via a gear attached to the shaft 214. Driven.

  Next, the heater unit (heating roller) 116 will be described. The heat pipe 207 is covered with a cylindrical heat-resistant film 201, and this heat-resistant film 201 is rotated by the rotation of the pressure roller 120 outside the heat pipe 207, and the heat pipe 207 does not rotate. Remains stopped. Inside the heat pipe 207, a wick 202 and a working fluid 205 are placed, and a portion of the wick 202 that is in surface contact with the ceramic heater 211 is flat. A heater pattern 212 of the ceramic heater 211 is coated with glass. Further, the ceramic heater 211 and the heat pipe 207 are in surface contact with good thermal conductive grease. The ceramic heater 211 and the heat pipe 207 are fixed by a heat-resistant mold member (not shown) such as a liquid crystal polymer and insulated from the primary heater pattern 212. The ceramic heater 211 generates heat when the power supply is controlled by the engine unit 105, thereby heating the heat-resistant film 201, and the film 201 heats the toner 230. At the same time, the ceramic heater 211 heats the heat pipe 207 and repeats the vaporization and liquefaction of the hydraulic fluid 205 based on the well-known heat pipe principle. The distribution is uniform.

  FIG. 3 is a perspective view showing the arrangement of the heat pipe 207 and the heat resistant film 201 of the heat fixing unit 110.

  A ceramic heater 211 is in surface contact with the lower surface of the heat pipe 207. The heat resistant film 201 slides around the heat pipe 207. The fixing members 317, 314, and 315 are formed of a heat-resistant mold member, and fix the heat pipe 207 to the frame side plate of the printer 101, and have a tapered shape so that the heat-resistant film 201 is not biased left and right. . A side plate is inserted between the fixing members 314 and 317. The thermistor 117 is a thermistor for measuring the temperature of the ceramic heater 211, and the thermistor 118 is the thermistor for measuring the temperature of the heat pipe 207. The thermal fuse 121 improves safety together with the relay 107 for interrupting. Here, the thermal fuse 121 is configured to cut off the power supply from the commercial power supply 122 due to the temperature of the ceramic heater 211 and the abnormally high temperature of the heat pipe 207. Reference numeral 318 denotes a connector for supplying power to the ceramic heater 211.

  FIG. 4 is a diagram for explaining the temperature change of the nip portion of the heat fixing device 110 according to the present embodiment, where the vertical axis indicates the temperature and the horizontal axis indicates the passage of time. In FIG. 4, reference numerals 903 and 904 indicate temperature changes when the heat pipe 207 is not used. Reference numerals 905 and 906 denote temperature changes in the present embodiment, in which the heat pipe 207 is employed and controlled using the temperature detection thermistor 117 of the heater 211 and the temperature detection thermistor 118 of the heat pipe 207. Here, the temperature range suitable for fixing is between T1 and T2. At time t0, when electric power starts to be supplied to the heater 211, the temperature of the heater 211 starts to rise. When there is no heat pipe, since the heat capacity is small, the temperature of the nip portion rises steeply as indicated by 903. In this case, an overshoot occurs at time t1, and thereafter, a temperature ripple due to temperature cycle unevenness of the film 201, presence / absence of paper, and the like occurs.

  On the other hand, when the heat pipe 207, the thermistor for heater 117, and the thermistor for heat pipe 118 are used, the temperature rise at the start of power supply is slow as indicated by 905 due to the heat capacity of the heat pipe 207. However, the temperature ripple is kept small.

  If the temperature of the heater 211 rises due to some failure, if the temperature is higher than the temperature T4, if the heat pipe 207 is not present, as shown by 904, it suddenly rises to the temperature T6. In contrast, in the case where the heat pipe 207 is provided and the heater 211 is controlled based on the temperature detected by the heater thermistor 117 and the heat pipe thermistor 118, as shown at 906, the maximum temperature rise is increased to the temperature T5. Can be suppressed. Thereby, damage to the pressure roller 120 can also be prevented. Further, when the working fluid 205 peculiar to the heat pipe 207 is insufficient in the evaporation portion, a phenomenon called dryout occurs, and a state where heat transport is not performed occurs. If this state continues for a long time, the pressure roller 120, the heat resistant film 201, the heat pipe 207, etc. will be damaged. It can be understood that the heater thermistor 117 and the heat pipe thermistor 118 are indispensable for the temperature control of the heat pipe 207 also for this measure.

  FIG. 5 is a view for explaining the temperature distribution in the width direction at the nip portion of the heat fixing device 110 of the center reference.

  The vertical axis represents temperature, and the horizontal axis represents the length in the width direction of the paper. Reference numeral 1303 denotes a temperature change in a configuration in which the heat pipe 207 is not used, and reference numeral 1304 denotes a temperature change according to the present embodiment. When a relatively narrow sheet having a sheet width of Y1 to Y4 is passed, the passing area of the sheet is indicated by 1316. Here, when the heat pipe 207 is not used, as indicated by reference numeral 1303, it can be seen that the temperature rises at the end where the sheet is not conveyed. If the printing operation is continued in this state, there is a concern about damage to the pressure roller 120, and thus processing such as slowing the printing speed is required.

  On the other hand, when the heat pipe 207 is used, as indicated by reference numeral 1304, it can be seen that the temperature distribution is substantially uniform along the paper width direction, and it is not necessary to reduce the printing speed or the like.

  FIG. 6 is a flowchart for explaining heater activation control in the engine unit 105 of the LBP 101 according to the present embodiment. A program for executing this processing is stored in the ROM 181 and is executed under the control of the CPU 180.

  This process is started to increase the temperature of the fixing device 110 by, for example, turning on the power or inputting a print job. First, in step S1, the temperature Tp of the heat pipe 207 and the heater 211 are detected by the thermistors 117 and 118. , And the detected temperatures are stored in variable areas Tp0 (temperature of the heat pipe 207) and Th0 (temperature of the heater 211) of the RAM 182 respectively. Next, in step S2, it is checked whether the temperature of the heat pipe 207 and the temperature of the heater 211 stored in the variable areas Tp0 and Th0 are lower than predetermined temperatures (Tpa and Tha), respectively. Here, these predetermined temperatures Tpa and Tha are temperatures close to room temperature of the heat pipe 207 and the heater 211, respectively. If this condition is satisfied, for example, it is determined that the LBP 101 has been turned off and the heater 211 has been cooled to a state close to room temperature, and the process proceeds to step S4. If not, the process proceeds to step S3. Execute startup processing other than room temperature. Here, as a case where step S3 is executed, for example, a case where the time has not passed since the previous printing process has been considered can be considered.

  In step S <b> 4, relatively large power is supplied to the heater 211 to start heat generation of the heater 211. At the same time, the timer 183 starts timing. In step S5, it is determined whether the time count TM by the timer 183 reaches a predetermined time TMa or whether the temperature of the heater 211 detected by the thermistor 117 reaches a predetermined temperature Thb. When neither condition is satisfied, step S5 is repeatedly executed, and the power supply to the heater 211 is continued during this time. Thus, in step S5, when the time measured by the timer 183 reaches the predetermined time TMa or the temperature of the heater 211 becomes equal to or higher than the predetermined temperature Thb, the process proceeds to step S6, and the temperature Tp of the heat pipe 207 is mainly set within the predetermined temperature range (Tpc). PID control is performed so that <Tp <Tpd), and auxiliaryly, it is monitored whether the temperature Th of the heater 211 is within a predetermined range (Thc <Th <Thd). In step S7, it is determined whether the printing process is finished and the heating operation of the heat fixing device 110 is finished. If finished, the process goes to step S9 to return to the main process by the CPU 180. When the printing is not finished, the process proceeds to step S8, where it is determined whether the temperature of the heat pipe 207 and the heater 211 is abnormally low or abnormally high. If not abnormal, the process returns to step S6. The process proceeds to the abnormal temperature process in step S10. In step S8, the temperature Tp of the heat pipe 207 is Tp <Tpb, Tp> Tpe, or the temperature of the heater 211 is Th <Thb so that the heater 211 does not run away and the heat pipe 207 does not dry out. , Th> Th is determined. Here, Tpb is the low temperature abnormality threshold of the heat pipe 207, Tpe is the high temperature abnormality threshold of the heat pipe 207, Thb is the low temperature abnormality threshold of the heater 211, and The is the high temperature abnormality threshold of the heater 211. Further, in the control in step S5, control is performed with emphasis on the temperature Th of the heater 211, and in the PID control in step S6 after the temperature of the heater 211 becomes stable, the temperature Tp of the heat pipe 207 is set. It is characterized by heavy control.

  As described above, according to the first embodiment, the ceramic heater 211 is installed on the bottom surface of the heat pipe 207, and both the thermistor 118 attached to the heat pipe 207 and the thermistor 117 attached to the ceramic heater 211 are used. The temperature of the fixing device 110 is controlled based on the temperature information. Accordingly, a substantially uniform temperature distribution can be generated with a simple configuration in the width direction of the transfer paper. Further, it is possible to provide a fixing device that prevents overshoot of the heater and rises quickly.

  Furthermore, since the dry-out phenomenon peculiar to a heat pipe can be prevented in advance, a highly safe fixing device can be realized.

  In the first embodiment, by using a heat pipe 207 having substantially the same size as the diameter of the film 201, the heat distribution in the width direction of the transfer paper can be made substantially uniform, and the entire film 201 is simultaneously warmed. An example of making the heat distribution of 201 uniform is shown. Furthermore, in the case of a small low-speed printer, the ability to make the temperature distribution of the entire film 201 uniform is slightly reduced if a small-diameter heat pipe is used, but sufficient performance can be obtained by making the temperature distribution of the heater 211 uniform. It can be demonstrated.

  The same effect can be obtained by rotating the pressure roller 120 and the heat pipe 207 upside down or rotating the relationship. Examples of the working fluid 205 according to the present embodiment include water, cermex, and the like, and copper, SUS, and the like are recommended as the container material.

[Embodiment 2]
Next, a heat fixing device according to Embodiment 2 of the present invention will be described.

  FIG. 7 is a cross-sectional view of the heat-fixing device according to the second embodiment, and the same parts as those in the first embodiment are indicated by the same symbols. In the first embodiment described above, the configuration in which the ceramic heater 211 is attached to one heat pipe 207 is shown, but in the second embodiment, one heat pipe is bent to form a film as two heat pipes. The configuration passed through 201 is shown.

  In the figure, the pressure roller 120 is made of a porous layer made of foamed rubber or the like, and is rotated by a bearing made of a heat conductive metal such as aluminum. The heat pipes 403 and 404 are covered with a 401 heat-resistant film 201 having a cylindrical shape. The heat resistant film 201 rotates following the rotation of the pressure roller 120. In each of the heat pipes 403 and 404, wicks 405 and 406 and hydraulic fluids 407 and 408 are placed, and a portion in surface contact with the ceramic heater 211 is flat. The heater pattern 412 of the ceramic heater 211 is coated with glass. The ceramic heater 211 and the heat pipes 403 and 404 are in surface contact with highly heat conductive grease. The fixing of the ceramic heater 211 and the heat pipes 403 and 404 and the film guide are made of a heat-resistant mold member (not shown) such as a liquid crystal polymer, positioning is performed, and the primary heater pattern 412 Insulated.

  FIG. 8 is a perspective view of the heat fixing device according to the second embodiment, and the same parts as those in FIG. 3 are indicated by the same symbols.

  Here, the heat pipes 403 and 404 are formed by bending one heat pipe. A thermistor 118 is attached to the heat pipe. On the other hand, a thermistor 117 is attached to the heater 211. Other configurations are substantially the same as those of the first embodiment.

  FIG. 9 is a diagram for explaining the positional relationship between the heater 211 and the heat pipe in the fixing device according to the second embodiment, and is a diagram viewed from directly above the transfer paper in a direction orthogonal to the transfer paper transport direction. It is. Since the other configuration of the LBP 101 according to the second embodiment is the same as that of the first embodiment, the description thereof is omitted.

  As is apparent from the figure, the heat pipes 403 and 404 are composed of two heat pipes, each of which is bent once by the outside of the sheet conveyance area. In this way, by bending the heat pipe outside the paper conveyance area, processing accuracy is not so required, so that the heat distribution at the folding position is not affected by the uneven distribution of heat due to the difference from the unbent part. There is an advantage that can be. Again, the thermistor 118 is attached to the heat pipe, and the thermistor 117 is attached to the ceramic heater 211. A thermal fuse 121 is attached so that the abnormal temperature of the ceramic heater 211 and the heat pipes 403 and 404 can be detected. The two heating element patterns 624 and 625 of the heater 211 are arranged to engage with the heat pipes 403 and 404, respectively. Thus, the film 201 and the heat pipes 403 and 404 can be heated more quickly. Reference numerals 622 and 623 denote connector connecting portions for supplying power to the ceramic heater. Reference numeral 620 denotes a passing area of the transfer paper.

  By using the fixing device 110 according to the second embodiment having the above configuration and performing the control described with reference to the flowchart of FIG. 6 of the first embodiment, the same effects as those of the first embodiment are obtained. Can be obtained.

  Furthermore, according to the second embodiment, a configuration has been shown in which the ability is greatly improved so that the heat distribution can be made substantially uniform by bending a thin heat pipe made of metal at low cost.

  Further, the heat pipe 404 is provided before coming into contact with the transfer paper, and the heat pipe 403 is provided after coming into contact with the transfer paper, so that the amount of heat remaining on the film 201 on the fixing side is fed back to the film 201 on the fixing side. This can improve the thermal efficiency of the entire fixing device.

  Moreover, it is possible not only to bend the heat pipe one time but also to further improve the heat transfer capability by bending a plurality of times.

[Embodiment 3]
FIG. 10 is a perspective view showing the arrangement of the heat pipe and heat resistant film 201 of the heat fixing unit 110 according to Embodiment 3 of the present invention. Since the other configuration of the LBP 101 according to the third embodiment is the same as that of the first embodiment, the description thereof is omitted.

  In the figure, reference numeral 703 denotes a heat pipe. A heating unit 721 is provided with a temperature fuse 121, a heater member 711, and a temperature detection thermistor 713 for the heater 711. The thermistor 713 is connected to the connector 719 and sends temperature information to the engine unit 105. The heater 711 is arranged in a coil shape along the inner periphery of the heat pipe 703, and is driven to generate heat by electric power supplied from the connector 718 via the thermal fuse 121. Reference numerals 717 and 715 are formed from a heat-resistant mold member, and the heat pipe 703 is fixed to the frame side plate of the LBP 101. The fixing members 717 and 715 are tapered so that the heat resistant film 201 does not move too much to the left and right. The thermistor 709 is a thermistor for detecting the temperature of the heat pipe 703.

  By using the fixing device 110 according to the third embodiment having the above configuration and performing the control described with reference to the flowchart of FIG. 6 of the first embodiment, the same effects as those of the first embodiment are obtained. Can be obtained.

  Furthermore, according to the third embodiment, a thermistor for detecting the temperatures of the heat pipe and the heater is also provided in the configuration in which a heating unit is provided at the end of the fixing device 110 in the paper width direction and heat is input from here. By installing the heater 711 and the heat pipe 703 as in FIG. 10, the same effects as those of the above-described embodiment can be obtained. Moreover, there exists an advantage that wiring etc. are simplified by employ | adopting the heat input system from an edge part.

[Embodiment 4]
FIG. 11 is a diagram illustrating attachment of the heat fixing unit 110 according to Embodiment 4 of the present invention. Since the other configuration of the LBP 101 according to the fourth embodiment is the same as that of the first embodiment, the description thereof is omitted. The configuration of the fixing device used in the fourth embodiment is assumed to have the configuration according to the third embodiment (FIG. 10).

  In FIG. 11, the fixing device shown in FIG. 10 is mounted as a fixing device of the LBP 101. 201 is a heat resistant film. The heat pipe 703 is heated from its end (left side in the figure) by the heater unit 721. The hydraulic fluid 205 stays in a biased manner as shown in the figure as the fixing device is inclined from the horizontal. Reference numerals 717 and 715 denote anti-shift members for the film 201 whose inside is processed into a tapered shape. The pressure roller 120 is rotationally driven via a gear 810, and the film 201 is configured to follow the rotation of the pressure roller 120. In FIG. 11, only the fixing device is inclined by θdeg from the horizontal, as indicated by 802. Reference numeral 811 denotes a paper cassette for stacking and storing a plurality of papers 114. Therefore, in this case, after the transfer, the paper 114 is conveyed while being leveled and sent to the fixing device.

  By attaching the fixing device in this manner, the heat supplied from the heater unit 721 can be quickly conducted to the entire heat pipe 703.

[Embodiment 5]
FIG. 12 is a diagram for explaining attachment of the heat fixing unit 110 according to the fifth embodiment of the present invention. Since the other configuration of the LBP 101 according to the fifth embodiment is the same as that of the first embodiment, the description thereof is omitted. The configuration of the fixing device used in the fifth embodiment is assumed to have the configuration according to the above-described third embodiment (FIG. 10).

  In the fifth embodiment, a case where all the conveying surfaces of the LBP 100 are inclined by a predetermined angle (θ) is shown. Here, the sheet feeding surface of the sheet 114 is also inclined by a predetermined angle (θ).

  FIG. 13 is a diagram for explaining the relationship between the temperature distribution in the longitudinal direction (paper width direction) of the heat pipe 703 of the fixing device 110 and the inclination of the fixing device 110.

  The vertical axis in FIG. 13 indicates the temperature of the nip portion, and the horizontal axis indicates the length in the width direction. Here, the sheet is passed between Y1 and Y2. A temperature distribution indicated by 1205 indicates a case where the temperature is tilted as shown in FIG. 12, and 1204 indicates a case where the temperature is tilted as shown in FIG. Further, reference numeral 1203 indicates a case where the fixing device 110 is installed horizontally. As is clear from this, when heat is supplied from the end of the heat pipe 703, the heat pipe itself has high heat conduction performance, but when installed horizontally, a temperature distribution of about 5 to 10 ° C. occurs in the width direction. On the other hand, as shown in FIGS. 11 and 12, the temperature distribution can be improved by inclining the heat pipe 703 with the heat supply side down.

  Here, as shown in FIG. 12, an almost uniform temperature distribution as shown by 1205 in FIG. 13 can be obtained by inclining all the paper conveyance surfaces from paper feeding to fixing and paper ejection. Further, by setting the paper at an angle in this way, it is possible to improve the paper mountability and further reduce the installation area of the printer apparatus 101.

1 is a block diagram showing a schematic configuration of a laser beam printer (LBP) which is an example of an image forming apparatus according to an embodiment of the present invention. 2 is a cross-sectional view illustrating a detailed structure of a heat fixing device according to Embodiment 1. FIG. FIG. 3 is a perspective view showing an arrangement of heat pipes and heat resistant films of the heat fixing unit according to the first embodiment. It is a figure explaining the temperature change of the nip part of the heat fixing device which concerns on embodiment of this invention. It is a figure explaining the temperature distribution of the width direction in the nip part of the center reference | standard heating fixing device which concerns on this Embodiment. It is a flowchart explaining the heater starting control in the engine unit of LBP which concerns on this Embodiment. It is sectional drawing of the heat fixing device which concerns on Embodiment 2 of this invention. 6 is a perspective view of a heat fixing device according to Embodiment 2. FIG. It is a figure explaining the positional relationship of the heater and heat pipe in the fixing device which concerns on this Embodiment 2. FIG. It is a perspective view which shows arrangement | positioning with the heat pipe and heat resistant film of the heat fixing part which concerns on Embodiment 3-5 of this invention. It is a figure explaining attachment of the heat fixing part which concerns on Embodiment 4 of this invention. It is a figure explaining attachment of the heat fixing part which concerns on Embodiment 5 of this invention. FIG. 6 is a diagram for explaining the relationship between the temperature distribution in the longitudinal direction (paper width direction) of the heat pipe of the fixing device according to the present embodiment and the inclination of the fixing device.

Claims (11)

A pressure roller;
A cylindrical member that rotates in contact with the pressure roller, and a heater serving as a heat source and conducting heat from the heater in a state where the relative position with respect to the pressure roller is held inside the cylindrical member. A heating roller comprising a heat pipe;
A temperature sensor for detecting the temperature of each of the heat pipe and the heater;
A fixing device comprising:   The fixing device according to claim 1, wherein the heat pipe includes two heat pipes obtained by bending a single pipe at a substantially central position.   The fixing device according to claim 1, wherein the heat pipe includes a working fluid for conducting heat from the heater. An image forming apparatus for fixing an image transferred to a recording medium by an electrophotographic process to form an image,
A fixing device according to any one of claims 1 to 3,
Heater driving means for energizing the heater to drive heat,
Control means for controlling the fixing device by controlling the heater driving means based on temperature information from the temperature sensor;
An image forming apparatus comprising:   The heater is disposed in the vicinity of an end portion in the longitudinal direction of the heat pulp, and the fixing device is attached to the image forming apparatus so that the end portion side is inclined downward. The image forming apparatus according to claim 4.   The image forming apparatus according to claim 4, wherein the control unit performs PID control.   The control means mainly performs temperature information from a temperature sensor for detecting a temperature of the heat pipe in performing image formation after the heater temperature reaches a predetermined temperature. Item 7. The image forming apparatus according to any one of Items 4 to 6. A control method for an image forming apparatus, comprising the fixing device according to claim 1, and fixing an image transferred to a recording medium by an electrophotographic process to form an image.
A heater driving step of energizing the heater and driving the heat generation;
A control step of controlling the heater based on temperature information of the heater pipe detected by the temperature sensor when the heater is driven in the heater driving step;
A control method comprising:   The heater is disposed in the vicinity of an end portion in the longitudinal direction of the heat pulp, and the fixing device is attached to the image forming apparatus so that the end portion side is inclined downward. The control method according to claim 7.   9. The control method according to claim 7, wherein PID control is performed in the control step.   In the control step, after the temperature of the heater reaches a predetermined temperature, the control when performing image formation mainly performs temperature information from a temperature sensor that detects the temperature of the heat pipe. Item 11. The image forming method according to any one of Items 8 to 10.

Images