JP3647229B2 - Image heating apparatus and image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present inventionComprises a heating member having a heating element that generates heat when energized and a film that moves in contact with the heating element, and the heating element and the pressure member are pressed against each other to form a nip portion. By passing the heating member through the nip part, the image on the heated member is formed by the heat from the heating member.The present invention relates to an image heating apparatus that performs image heating processing, and an image forming apparatus that includes the image heating apparatus as an image heating fixing apparatus.
[0002]
[Prior art]
Conventionally, as an image heating and fixing device provided in an image forming apparatus having an arbitrary image forming process means such as an electrophotographic process, an electrostatic process, and a magnetic recording process, a recording material on which an unfixed toner image is formed and supported ( A heated member) is passed through a fixing nip portion as a nip portion formed by a fixing roller and a pressure roller rotating in pressure contact with each other, thereby fixing the toner image on the recording material as a permanent image. A so-called heat roller type image heating apparatus is widely known.
[0003]
This is a basic component member consisting of a pair of mutually contacting and rotating rollers of a heating roller (fixing roller) as a heating member and a pressure roller as a pressure member. The heating roller is a cylinder made of metal or the like having good thermal conductivity. A halogen heater as a heating body (heat generation source) is provided inside the roller base.
[0004]
The heating roller is heated by a halogen heater to control the roller surface temperature.ThermistorTemperature detection so that the roller surface temperature is maintained at a predetermined fixing temperature, that is, the temperature in the fixing nip portion N is a temperature at which an unfixed toner image does not cause fixing failure or hot offset ( The temperature is controlled by energization so as to be maintained at (α ° C. to β ° C.). The pressure roller is formed by forming a material layer having heat resistance such as silicon rubber around the core metal and having predetermined elasticity.
[0005]
The above-mentioned heating roller type image heating apparatus is indeterminate of a recording material in which an unfixed toner image is formed and supported on a fixing nip portion (heating nip portion, pressure nip portion) formed by a pressure roller and a heating roller. The toner image surface side of the contact is introduced with the fixing roller side and is nipped and conveyed, whereby the unfixed toner image is fused and fixed on the recording material by heating and pressurizing at the fixing nip portion.
[0006]
In addition to the heat roller type image heating apparatus, a so-called film that heat-fixes an unfixed toner image on a recording material (heated member) through a film between a heater portion and a pressure roller. JP-A-63-313182, JP-A-2-157878, JP-A-4-44075, JP-A-4-204980, and the like have been disclosed as a heating type image heating apparatus.
[0007]
This is because a fixing nip portion is formed as a nip portion by sandwiching a thin heat-resistant film between a ceramic heater as a heating body (heat generation source) and a pressure roller as a pressure member. The recording material on which an unfixed toner image is formed and supported is introduced between the film and the pressure roller with the unfixed toner image surface side of the film side, and is nipped and conveyed together with the film. In the fixing nip portion, the heat of the ceramic heater is applied to the recording material through a film and heated and pressed to fix the unfixed toner image on the recording material.
[0008]
The film is heated by the heat of the ceramic heater in the fixing nip portion, and the recording material is heated by the heated film. The ceramic heater and the film constitute a heating member. Ceramic heater was provided on the backThermistorThus, the temperature is detected, and the heater temperature generated by energizing the ceramic heater is controlled to be kept constant. Such control is performed by controlling the temperature of the film in the fixing nip N to a temperature (α ° C. to β ° C.) at which an unfixed toner image does not cause fixing failure or hot offset.
[0009]
Since the film heating type image heating apparatus uses a thin film, the heating member has a much smaller heat capacity than a heat roller type image heating apparatus using a heating roller. For this reason, in order to heat and fix an unfixed toner image on the recording material, heat from the ceramic heater can be efficiently applied to the recording material, and only the fixing nip portion is heated so that the image forming apparatus Quick start heating and fixing with a short waiting time from power ON to printable state is realized. Furthermore, since the heat capacity of the heating member is kept small, it is not necessary to warm the heating member even during standby, and there is an advantage that power consumption can be kept low.
[0010]
[Problems to be solved by the invention]
By the way, in an image forming apparatus such as a laser beam printer provided with an image forming means of an electrophotographic process type and having the film heating type image heating apparatus as an image heating fixing apparatus, in recent years, an electron as an image carrier is used. With the progress of the processing technology of the scanning optical system that forms an image (latent image) with a laser beam on the photographic photoreceptor, it becomes possible to increase the resolution of the formed image on the electrophotographic photoreceptor as the image carrier. : 600 dpi Print capacity: 12 sheets / minute (Process speed (carrying speed) of about 70 mm / sec), Resolution: 1200 dpi Print capacity: 6 sheets / minute (Process speed (carrying speed) of about 35 mm / second) sec) high-resolution mode laser beam printers have been commercialized.
[0011]
In the film heating type image heating apparatus used in the image forming apparatus having a plurality of process speeds as described above, the amount of heat carried to the recording material, the pressure roller, or the film is larger when the process speed is faster. Therefore, in order to keep the temperature in the fixing nip within the above-described α ° C. to β ° C. at any process speed, the temperature control temperature of the ceramic heater (hereinafter referred to as the heater) of the heating member increases as the process speed increases. It becomes high temperature. For example, when switching from a fast process speed to a slow process speed, the temperature control temperature of the heater must be switched to a lower temperature control temperature. If the temperature of the heater is maintained at a high temperature control temperature at a high process speed and the process speed is slow, the time for the heater to heat the film and the pressure roller becomes longer than that at the high speed. Therefore, the maximum temperature of the film and the pressure roller is higher than that at high speed. In this case, the time during which the film and the pressure roller are not heated also becomes longer and the cooling time becomes longer. However, since the heating effect by the temperature control of the heater is more effective, the maximum temperature of the film and the pressure roller is increased. Is higher than that at high speed.
[0012]
In addition, when the CPU as the control means performs two switching controls of the process speed and the heater temperature control temperature, the CPU receives the two switching signals of the process speed and the heater temperature control temperature. It is impossible in reality to start together and complete instantly. In both cases, there is a response time from the start of switching to completion. Therefore, especially when the response time for switching the heater temperature control temperature is longer than the response time for switching the process speed, even if you try to switch from a fast process speed to a slow process speed at the same time, the process temporarily Despite the slow speed, the temperature of the heater remains high, and the temperature of components (such as a pressure roller and a film) in the image heating and fixing apparatus becomes higher than that during normal use. In other words, even when switching to a slow process speed is completed, switching to a low temperature control temperature of the heater has not yet been completed, and the heater temperature remains high, resulting in the configuration within the image heating and fixing device. Parts (such as pressure rollers and films) become hotter than normal use.
[0013]
The phenomenon that the temperature of components in such an image heating and fixing device becomes higher than that during normal use is when the heater temperature control temperature is switched before switching from a slow process speed to a fast process speed. Also seen in In this case, since the process speed is switched after the heater is switched to a high temperature control temperature, the heater temperature rises to a high temperature control temperature for a high process speed when the process temperature is low. The components (pressure roller, film, etc.) in the heat fixing device become higher than the temperature during normal use.
[0014]
As described above, if the heater temperature is switched at the same time as the process speed is switched or before the process speed is switched, the components (such as the pressure roller and film) in the image heating and fixing device will be lower than the temperature during normal use. There is a risk of damage due to high temperatures. In addition, the fear of damage to the components in the image heating and fixing apparatus also occurs in the heat roller type image heating and fixing apparatus, and the components (pressure roller) in the image heating and fixing apparatus are There is a risk of breakage due to higher temperatures than in normal use.
[0015]
According to the present invention, in the image heating and fixing apparatus, when two switching controls, that is, the process speed (conveying speed) and the temperature adjustment temperature of the heater of the heating member, are performed, the components become higher than the temperatures during normal use. It was made in view of the difficulty that the component temperature is higher than that during normal use so that the component is not affected by the temperature at the high transfer speed at the low transfer speed. It is an object of the present invention to provide a heating device, an image heating device, and an image forming apparatus that can prevent the above-described problem.
[0016]
[Means for Solving the Problems]
  The present invention is characterized by the following configuration.TheAn image heating apparatus and an image forming apparatus.
[0017]
  (1) A heating member having a heating body that generates heat by energization and a film that moves in contact with the heating body, and the heating body and the pressure member are pressed against each other to form a nip portion. In an image heating apparatus that heats an image on a heated member with heat from the heated member by passing the heated member through the nip portion, the first conveying speed and a second conveying speed that is faster than the first conveying speed. The conveyance control means capable of conveying the heated member, the temperature detection member for detecting the temperature of the heating member, and the detected temperature from the temperature detection member corresponding to the first and second conveyance speeds. And an energization control means for controlling energization to the heating body so as to be at a second predetermined temperature, the energization control means 1) from the first conveying speed to the second conveying speed. When switching to, the heated member is The heating member is switched from the first predetermined temperature to the second predetermined temperature at a timing such that the heating member reaches the second predetermined temperature after switching to the conveyance speed, and 2) the member to be heated Is switched from the second transport speed to the first transport speed, the second predetermined speed is such that the heating member reaches the first predetermined temperature before the heated member switches to the first transport speed. An image heating apparatus that switches from a temperature to the first predetermined temperature.
  (2) An image forming unit that forms an image on a member to be heated, and the image heating apparatus according to (1) that performs image heating processing on the image on the member to be heated conveyed from the image forming unit side. An image forming apparatus.
[0044]
    [Operation]
  Image heating apparatus and image forming apparatus according to the present inventionIn the above, as described above, when the heated member is switched from the first conveyance speed to the second conveyance speed that is faster than the first conveyance speed, the heating member is switched to the second conveyance speed and then the heating member is moved to the second conveyance speed. At a timing at which the second predetermined temperature corresponding to the speed is reached, the first predetermined temperature corresponding to the first transport speed is switched to the second predetermined temperature corresponding to the second transport speed, and heated When the member is switched from the second transport speed to the first transport speed that is slower than the second transport speed, the heating member has a first predetermined speed corresponding to the first transport speed before the heated member switches to the first transport speed. At a timing at which the temperature is reached, the second predetermined temperature corresponding to the second transport speed is switched to the first predetermined temperature corresponding to the first transport speed.

[0045]
  As a result, the conveyance speed(Second transport speed)The slower transfer speed(First transfer speed)When switching to, it becomes possible to switch the temperature of the heating member to the temperature for the slow conveyance speed between the switching of the temperature of the heating member and the switching to the slow conveyance speed. Sometimes, it is possible to avoid that the component is affected by the temperature at a high conveyance speed.
[0046]
Also, when switching the transport speed to a faster transport speed, it becomes possible to switch the temperature of the heating member to a temperature for a faster transport speed after the transport speed is switched, and thus faster when the transport speed is lower than the fast transport speed. It can be avoided that the component is affected by the temperature at the conveyance speed.
[0047]
Therefore, it is possible to prevent the temperature of the component parts from becoming higher than that during normal use when the conveyance speed is low.
[0048]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a heating device, an image heating device, and an image forming apparatus according to the present invention will be described in more detail based on embodiments shown in the accompanying drawings.
[0049]
[First Embodiment]
(A) of FIG. 1 is a schematic block diagram which shows an example of the heating apparatus which concerns on this invention. FIG. 1B is a schematic configuration diagram showing an example of a laser beam printer as an image forming apparatus according to the present invention, and a heating device (hereinafter, image heating device) shown in FIG. 11).
[0050]
  The laser beam printer (hereinafter referred to as LBP) 16 of the present embodiment has a process speed (conveyance speed) of 80 mm / sec.(Second transport speed), And 40 mm / sec(First transfer speed)When the process speed is 80 mm / sec, an image with a resolution of 600 dpi is output. When the process speed is 40 mm / sec, an image with a resolution of 1200 dpi is output (that is, the scanner rotation speed is constant). The resolution is doubled to 1200 dpi by switching the process speed from 80 mm / sec to 40 mm / sec, which is a half.)
[0051]
The image heating device 11 is a film heating type heating device. As shown in FIG. 1A, the image heating device 11 is a heat-resistant thin film (hereinafter, referred to as a fixing film) 1a, a stay holder 3, and a heating body. A heating member 1 including the heater 4 and an elastic pressure roller 2 as a pressure member that forms a fixing nip portion (nip portion) N with the fixing film 1a sandwiched between the heater 4 and the heater 4. The heater 4 is provided along a direction orthogonal to the moving direction of the film 1a. For example, a highly heat conductive ceramic 4a having a thickness of 1 mm, and an energization heating resistor layer having a resistance value of 25Ω provided on the lower surface of the ceramic 4a. 4b (see FIG. 2A). A thermistor (temperature detection member) 5 as a temperature detection element is provided on the upper surface of the ceramic 4a. The output signal of the thermistor 5 is input to the CPU 7 via the A / D converter 6. The CPU 7 controls the energization power to the heater 4 via the AC driver 8 based on the input signal, and adjusts the surface temperature of the heater 4 to a predetermined temperature. Specifically, the energization control unit 7a of the CPU 7 energizes the energization heating resistor layer 4b so that the heater temperature detected by the thermistor 5 is maintained at a predetermined substantially constant temperature (fixing temperature of an unfixed toner image to be described later). Control. Thereby, the heater 4 is heated and adjusted to a predetermined fixing temperature. Reference numeral 9 denotes a commercial AC power source.
[0052]
Here, the basic configuration of the heating device 11 will be described in more detail with reference to FIGS.
[0053]
The fixing film 1a is a cylindrical member, and is conveyed in the direction of arrow a while being in close contact with and sliding on the surface of the heater 4 in the fixing nip portion N by a driving means (not shown) or the rotational force of the elastic pressure roller 2. Moved. The fixing film 1 a has a thickness as thin as 20 to 70 μm in order to efficiently apply the heat of the heater 4 to the recording material P as a heated member at the fixing nip portion N. The fixing film 1a has a three-layer structure of a film base layer, a primer layer, and a releasable layer. The film base layer side is the heater 4 side, and the releasable layer side is the elastic pressure roller 2 side. The film base layer is made of polyimide, polyamideimide, PEEK or the like having higher insulation than the glass protective layer 4c of the heater 4, and has heat resistance and high elasticity. Further, the mechanical strength such as the tear strength of the entire fixing film 1a is maintained by the film base layer. The primer layer is formed as a thin layer having a thickness of about 2 to 6 μm. The releasable layer is a toner offset prevention layer for the fixing film 1a, and is formed by coating a fluorine resin such as PFA, PTFE, FEP or the like to a thickness of about 10 μm.
[0054]
The stay holder 3 is formed of, for example, a heat-resistant plastic member, and holds the heater 4 and also serves as a conveyance guide for the fixing film 1a.
[0055]
The heater 4 is fixedly supported by the stay holder 3 and is heated and adjusted to a predetermined temperature by energization from the CPU 7. As the heater 4, a ceramic heater is generally used. For example, current-carrying heating resistance of silver palladium or the like along the substrate length (perpendicular to the drawing) on the surface of ceramic 4a (surface facing the fixing film 1a) having electrical insulation, good thermal conductivity and low heat capacity such as alumina The layer 4b is formed by screen printing or the like, and the energization heating resistance layer forming surface is covered with a thin glass protective layer 4c (see FIG. 2A). In the ceramic heater 4, when the energization heat generating resistance layer 4b is energized, the energization heat generation resistance layer 4b generates heat, and the entire heater including the ceramic 4a and the glass protective layer 4c is rapidly heated. The temperature rise of the heater 4 is detected by a thermistor 5 as a temperature detection member installed on the back surface of the heater and fed back to the energization control unit 7a of the CPU 7.
[0056]
As shown in FIG. 2B, the thermistor 5 that detects the temperature of the heater 4 is in contact with the back surface of the heater 4, and the temperature control of the heater 4 is performed according to the temperature detected by the thermistor 5. Made. Similarly, a thermo-protector TP such as a temperature fuse or a thermo switch is in contact with the back surface of the heater 4 in order to cut off the energization of the energization heating resistor layer 4b of the heater 4 during a runaway.
[0057]
Thus, in the heating device 11 of the film heating system using the thin film 1a for fixing, the elastic pressure roller 2 having the elastic layer 2a is provided for the high rigidity of the ceramic heater 4 as a heating body. The flattened bottom surface of the heater 4 that has been pressed is flattened at the pressure contact portion to form a fixing nip portion N having a predetermined width, and only the fixing nip portion N is heated to realize quick start heating and fixing. .
[0058]
In the above configuration, the arrangement relationship between the energization heating resistor layer 4b of the heater 4 and the elastic pressure roller 2 will be described with reference to FIG. The width W is formed to be slightly narrower than the width D of the elastic layer of the elastic pressure roller 2 that is pressed through the fixing film 1a, and a recording in which a toner image t as an unfixed image is formed and supported. Compared with the conveyance region of the material P, it is formed with the same or slightly wider width. As a result, the heat generated by energizing the energization heat generating resistance layer 4b of the heater 4 is applied to the recording material P conveyed between the fixing film 1a and the elastic pressure roller 2, and the toner on the recording material P is supplied. It acts to melt and fix the image t.
[0059]
The heating device 11 having such a configuration heats and adjusts the heater 4 to a predetermined temperature, and as shown in FIG. 2A, the fixing film 1a is conveyed and moved in the direction of arrow a. When the recording material P on which the toner image t is formed and supported is introduced into the fixing nip portion N, the recording material P is brought into close contact with the surface of the fixing film 1a and is nipped and conveyed together with the fixing film 1a. The The portion of the recording material P that has passed through the fixing nip N is peeled off from the surface of the fixing film 1a and conveyed.
[0060]
Next, the configuration of the LBP 16 will be described with reference to FIG.
[0061]
The LBP 16 includes a main motor 10, an image heating and fixing device 11, and a transfer.roller13. Image forming means 20 having electrophotographic photosensitive drum 12 as an image carrier, before transferroller(Resistroller14) Paper feedroller15 is provided with a paper feed cassette 17 and a conveyor belt 18 and is driven and controlled by the CPU 7 described above.
[0062]
In addition to the electrophotographic photosensitive drum 12, the image forming unit 20 applies a laser beam to the charging unit 21 that uniformly charges the surface of the electrophotographic photosensitive drum 12, and the electrophotographic photosensitive drum 12 charged by the charging unit 21. A scanner unit 22 that forms a latent image of a target formed image by irradiation, a developing unit 23 that visualizes the latent image formed on the electrophotographic photosensitive drum 12 with toner as a developer, and a developing unit 23 Transfer for transferring a visualized toner image onto a recording material Proller13 and a cleaning unit 24 that wipes and removes the toner remaining on the electrophotographic photosensitive drum 12 after the transfer of the toner image.
[0063]
Before transcriptionroller14. Electrophotographic photosensitive drum 12, conveyor belt 18 and pressurizationroller2 is connected to the main motor 10 via a gear box (not shown), and constitutes a transport mechanism C as transport means for transporting the recording material P. But before transcriptionroller14. Electrophotographic photosensitive drum 12, conveyor belt 18 and pressurizationrollerNo. 2 is such that the conveyance speed of the recording material P is uniformly switched to 80 mm / sec or 40 mm / sec by switching the rotation speed of the main motor 10 in accordance with a command from the CPU 7. Before transcriptionroller14 has a clutch (not shown), and when the clutch is released by a command from the CPU 7, the connection with the main motor 10 is cut off, the rotation is stopped, and the recording material P can be stopped immediately. The recording material P can be transferred to the electrophotographic photosensitive drum 12 at an arbitrary timing by connecting the clutch again by a command from the CPU 7.roller13 to the transfer nip portion. Further, only the paper feed roller 15 is driven by a paper feed motor (not shown) which is a drive motor independent of the main motor 10.
[0064]
Next, the processing operation of the LBP 16 will be described with reference to FIG.
[0065]
First, paper is fed from the paper cassette 17roller15 picks up the recording material P, then, before transferroller(Resistroller) 14, the recording material P is transferred to the electrophotographic photosensitive drum 12.roller13 is transferred to a nip portion for transfer between the printer 13 and the printer. Then, transfer from the electrophotographic photosensitive drum 12rollerThe recording material P onto which the toner image t has been transferred by the toner 13 is conveyed to the conveying belt 18 and passed through the heating device 11 so that the toner image t is fixed as a permanent image. Is done.
[0066]
The CPU 7 that drives and controls the LBP 16 is equivalent to switching the transport speed of the electrophotographic photosensitive drum 12 when switching the resolution even when receiving a resolution switching signal from an external input device such as a personal computer (not shown). Since the transfer speed cannot be switched while the latent image is being formed on the photosensitive drum 12, during development, or during transfer, the recording material P carrying the last unfixed image at the old resolution before the resolution change is image heated. The switching of the conveyance speed and the temperature control temperature of the heater is suspended until it passes through the apparatus 11, and a command for executing each switching is issued after the recording material P has passed. The switching of the conveyance speed and the temperature control temperature of the heater is performed by the switching control unit 7b of the CPU 7.
[0067]
Below, switching of the conveyance speed and the temperature control temperature of the heater by the switching control unit 7b of the CPU 7 will be described with reference to the sequence chart shown in FIG. 3A is a sequence chart for switching from a resolution of 1200 dpi and a process speed of 40 mm / sec to a resolution of 600 dpi and a process speed of 80 mm / sec. FIG. 3B is a sequence chart of a resolution of 600 dpi and a process speed of 80 mm / sec. 3 is a sequence chart for switching from a resolution of 1200 dpi to a process speed of 40 mm / sec.
[0068]
First, a case where the resolution is switched from 1200 dpi to 600 dpi will be described.
[0069]
When the CPU 7 receives the resolution switching signal, it first pays out an unfixed image (toner image) with an old resolution (1200 dpi) (passes through the image heating and fixing device 11). If a latent image having an old resolution (1200 dpi) is being formed on the electrophotographic photosensitive drum 12 or development is being performed, an unfixed image is formed on the electrophotographic photosensitive drum 12 at the old resolution upon completion of the image formation. Is finished, and then the unfixed image is paid out. When paying out this unfixed image,roller14 clutch is opened and paper is fed from paper cassette 17roller15 is the leading edge of the new recording material P fed by 15 before transfer.roller14 and the recording material P is on standby as a recording material carrying an image of the next resolution (600 dpi).
[0070]
Here, for convenience, the time when the last recording material P on which an unfixed image has been formed and carried at a resolution of 1200 dpi has passed through the fixing nip portion N of the image heating and fixing device 11 after the CPU 7 receives the resolution switching signal. The conveyance speed of the recording material P andheater4 is the origin O of the time for switching the temperature control temperature.
[0071]
When the last recording material P passes through the fixing nip portion N of the image heating and fixing device 11, the switching control portion 7b of the CPU 7 changes the rotation speed of the main motor 10 after 0.5 sec from the origin O to change the conveyance speed to 40 mm / mm. A command to change from sec to 80 mm / sec is issued to the main motor 10. The rotation speed of the main motor 10 is changed by the switching control unit 7b controlling the voltage applied to the main motor 10. 1 sec after completion of change (switching) of the conveyance speed, before transferrollerPre-transfer by connecting 14 clutchesroller14 opens the recording material P. The recording material P enters the image heating and fixing device 11 before transfer.roller14 is 4.0 seconds, 3 seconds after the recording material P is released.
[0072]
Further, the switching control unit 7b of the CPU 7 does not wait until 4.0 sec when the recording material P enters the image heating and fixing device 11.heater4 is set to the target temperature and the entire image heating and fixing apparatus 11 is warmed up 1.5 seconds after the origin O.heaterA command to change the temperature control mode 4 to a high temperature control mode for 600 dpi is issued.
[0073]
Next, a case where the resolution is switched from 600 dpi to 1200 dpi will be described.
[0074]
Similarly, when the last recording material P on which an unfixed image is formed and supported at a resolution of 600 dpi passes through the fixing nip portion N of the image heating fixing device 11 after the CPU 7 receives the resolution switching signal, The origin O of the time for switching between the conveyance speed of the recording material P and the temperature control temperature of the heater.
[0075]
  When the last recording material P passes through the fixing nip N of the image heating and fixing apparatus 11, the switching control unit 7b of the CPU 7 issues a command to switch the temperature adjustment mode of the heater 4 to 1200 dpi after 0.5 sec from the origin O. put out. In other words, the target temperature of the heater 4 is a low temperature control temperature for 1200 dpi.(First predetermined temperature corresponding to the first transport speed)Is lowered. Then, after 2.5 seconds from the origin O, a command to change the rotation speed of the main motor 10 and change the conveyance speed from 80 mm / sec to 40 mm / sec is issued. The rotation speed of the main motor 10 is stable at 3.0 seconds 0.5 seconds after the output of the conveyance speed switching command signal, and the conveyance speed of the recording material P by the conveyance mechanism C is also stabilized. The pre-transfer roller 14 releases the recording material P by connecting the 14 clutches. The recording material P enters the image heating and fixing device 11 at 9.0 sec, 6.0 seconds after the recording material P is released from the pre-transfer roller 14.
[0076]
FIG. 4 shows a resolution for 600 dpi and a resolution of 1200 dpi.heaterThe correspondence of each temperature of 4 temperature control modes is illustrated. In this embodiment, as shown in FIG.heaterAs the temperature control temperature is multi-step temperature control and the number of continuous sheets of recording material P increases,heaterA temperature control mode is adopted in which the temperature control temperature decreases.
[0077]
As described above, when the laser beam printer 16 of the present embodiment is switched from a high conveyance speed (80 mm / sec) to a low conveyance speed (40 mm / sec), as shown in FIG.heater4 when the temperature control temperature is switched, in other words, between the time when the temperature control temperature of the heating member 1 is switched (after 0.5 sec from the origin O) and the time when the speed is switched to the slow conveyance speed (2.5 sec after the origin O). Within the time Tb, the temperature adjustment temperature of the heating member 1 for the high conveyance speed is lowered to the temperature adjustment temperature for the low conveyance speed, so that the influence of the temperature adjustment temperature at the high conveyance speed is imaged at the low conveyance speed. Components such as the film 1a and the pressure roller 2 constituting the heat fixing device 11 are not received.
[0078]
  In addition, when switching the slow conveyance speed to the high conveyance speed, as shown in FIG. 3A, a certain time (0.5 seconds) from the point when the switching to the high conveyance speed is completed (after 1 sec from the origin O). Sec) Temperature control temperature of heater 4 for high transfer speed after Ta has elapsed(Second predetermined temperature corresponding to the second transport speed)In other words, since the switching of the temperature adjustment temperature of the heating member 1 to a high conveyance speed is started, the effect of the temperature adjustment temperature at the high conveyance speed at the low conveyance speed is image-heated. Components such as the film 1a and the pressure roller 2 constituting the fixing device 11 are not received.
[0079]
Accordingly, it is possible to avoid that the components such as the film 1a and the pressure roller 2 of the image heating and fixing device 11 become higher in temperature (over temperature rise) than in normal use.
[0080]
As described above, in the LBP 16 of the present embodiment, the recording material P is always transferred at a low speed of 40 mm / sec, or from a high speed of 80 mm / sec to a low speed of 40 mm / sec. When the speed of the transition period is high, the high temperature control temperature at the high transfer speed isheaterBy intentionally avoiding that it is emitted from 4, the component parts of the image heating and fixing device 11 are prevented from becoming hotter (overheated) than during normal use.
[0081]
Further, while the unfixed image of the old resolution before the resolution switching is being dispensed, the recording material P on which the next new resolution image is formed and supported is transferred.rollerAnd by changing the transport speed of the recording material P in the transport mechanism C without temporarily stopping the main motor 10, the transport speed of the transport mechanism C with temporary stop of the main motor 10 is changed. Compared with the case of changing the recording material conveyance speed, the time required for the subsequent multi-rotation and the pre-multi-rotation can be omitted, and the time required for switching the resolution can be greatly reduced.
[0082]
As described above, in the present embodiment, when the high conveyance speed (80 mm / sec) is switched to the low conveyance speed (40 mm / sec), the time before the conveyance speed starts to decrease (at 2.5 sec) is earlier. When the temperature of the heating member 1 is switched to the temperature for the slow conveyance speed (see FIG. 3B), and the slow conveyance speed (40 mm / sec) is switched to the high conveyance speed (80 mm / sec), the conveyance speed is Since the temperature of the heating member 1 is switched to a temperature for a high conveyance speed after the speed is increased (at the time of 1 sec) (see FIG. 3A), the film 1a of the image heating fixing device 11 and the additional heating temperature are increased. Although the pressure roller 2 is prevented from being heated to a higher temperature (overheating) than during normal use, the same applies to the overheating of the film 1a and the pressure roller 2 even if the following configuration is adopted. The effect Door can be.
[0083]
That is, when switching the high transport speed to the slow transport speed, the temperature of the heating member 1 is switched to the temperature for the slow transport speed before the transport speed is slow (at 3 sec in FIG. 3B), When switching from a low conveyance speed to a high conveyance speed, a configuration is adopted in which the temperature of the heating member is switched to a temperature for a high conveyance speed after the conveyance speed starts to increase (at 1 sec in FIG. 3A). be able to.
[0085]
[Second Embodiment]
Next, a second embodiment will be described. In the second embodiment, an image heating fixing device used for a laser beam printer having two resolutions of 1200 dpi (process speed 40 mm / sec) and 600 dpi (process speed 80 mm / sec) and the laser beam printer itself are applied.
[0086]
A laser beam printer (hereinafter referred to as LBP) as an image forming apparatus in the present embodiment is provided with a clutch in a gear box (not shown) connecting the main motor 10 and the pressure roller 2 of the image heating and fixing apparatus 11, and 600 dpi. The configuration is the same as that of the laser beam printer 16 of the first embodiment except that a function of changing only the conveying speed of the pressure roller 2 by a clutch is added when switching the resolution from 1 to 1200 dpi.
[0087]
In the LBP 16 of the present embodiment, there are a total of two gears that can be changed by the clutch provided in the gear box. One is a high gear, and even when the main motor 10 rotates at a rotational speed that gives a process speed of 40 mm / sec to another conveyance system (conveyance system between the pre-transfer roller 14 and the image heating fixing device 11). The process speed of only the pressure roller 2 is set to 80 mm / sec. The other one is a Low gear, which is normally used, and makes the process speed of the pressure roller 2 the same as the process speed of other transport systems.
[0088]
The switching of the resolution in the LBP 16 of the present embodiment, that is, the procedure of switching the resolution from 1200 dpi to 600 dpi is the same as the LBP procedure of the first embodiment (see FIG. 5A), but the resolution is changed from 600 dpi to 1200 dpi. The procedure for switching to is performed by another procedure using the above-mentioned high gear. This procedure will be described with reference to a sequence chart shown in FIG.
[0089]
5 (a) and 5 (b), as in the first embodiment described above, the last recording material on which an unfixed image is formed and supported at a resolution of 600 dpi after the CPU 7 receives a resolution switching signal. The point of time when P passes through the fixing nip N of the image heating fixing device 11 is the origin O of the switching time of the recording material P conveyance speed and the heater temperature control temperature.
[0090]
When the last recording material P passes through the fixing nip N of the image heating and fixing apparatus 11, the switching control unit 7b of the CPU 7heaterSwitching of the temperature control mode 4, switching from the normal gear (Low gear) to the High gear by the clutch of the pressure roller 2, and the process speed of the conveying system other than the pressure roller 2 is set to 80 mm with the rotation speed of the main motor 10. The switching to change the rotation speed from / sec to 40 mm / sec is executed simultaneously.
[0091]
heaterBy switching the temperature control mode 4 after 0.5 seconds from the origin O,heaterThe target temperature of 4 is lowered to a low temperature controlled temperature for 1200 dpi.
[0092]
Further, since it takes 0.5 sec for the rotation speed of the main motor 10 to shift to 40 mm / sec, the gear change is performed instantaneously, so the conveying speed of the pressure roller 2 is instantaneously 80 mm / sec. Will be faster.
[0093]
When the rotation speed of the main motor 10 shifts to 40 mm / sec and the process speed of the transport system other than the pressure roller 2 becomes 40 mm / sec, 1.0 sec.rollerBefore recording material P with 14 clutches connected and stoppedroller14 opens. This recording material P is before transferrollerThe image heating and fixing device 11 is entered at 7.0 seconds after 6.0 seconds from the release of the recording material P of 14. AndheaterThe gear is returned to the low gear at 3.0 sec when the temperature of 4 has reached the low temperature control temperature at which the temperature has been sufficiently lowered, so that the transport speed is 40 mm / sec, which is the same as other transport systems.
[0094]
Note that the correspondence between the temperatures in the temperature control mode of the heater 4 for resolution 600 dpi and resolution 1200 dpi in this embodiment is the same as that in the first embodiment shown in FIG.
[0095]
As described above, when the laser beam printer 16 of the present embodiment is switched from a high conveyance speed (80 mm / sec) to a low conveyance speed (40 mm / sec), as shown in FIG.heater4 when switching the temperature control temperature, in other words, between the time when the temperature control temperature of the heating member 1 is switched (after 0.5 sec from the origin O) and the time when the slow transfer speed is switched (after 3.5 sec after the origin O). Within the time Tb, the temperature adjustment temperature of the heating member 1 for the high conveyance speed is lowered to the temperature adjustment temperature for the low conveyance speed, so that the influence of the temperature adjustment temperature at the high conveyance speed is imaged at the low conveyance speed. Components such as the film 1a and the pressure roller 2 constituting the heat fixing device 11 are not received.
[0096]
Further, when switching from a low transport speed to a high transport speed, as shown in FIG. 5A, a fixed time (0.5 sec.) From the point when switching to the high transport speed is completed (after 1 sec from the origin O). Seconds) After Ta passes,heaterIn other words, since the switching of the temperature adjustment temperature of the heating member 1 to a high conveyance speed is started, the temperature adjustment temperature at the high conveyance speed at the low conveyance speed is started. The components such as the film 1a and the pressure roller 2 constituting the image heating and fixing device 11 are not affected by the above.
[0097]
Further, in the present embodiment, as described above, the result that the transport speed of the recording material P by the pressure roller 2 and the transport speed of the recording material P by other transport systems can be divided into different transport speeds by the high gear. ,heater4 does not wait for the temperature control temperature to decrease (decrease from the high temperature control temperature to the low temperature control temperature), in other words, without the temperature control temperature decrease of the heating member 1 and before the transfer.roller14, the recording material P can be released, and the resolution switching from 600 dpi to 1200 dpi is advantageous in that switching can be performed faster than in the first embodiment.
[0098]
As described above, in the present embodiment, when the high conveyance speed (80 mm / sec) is switched to the low conveyance speed (40 mm / sec), the time before the conveyance speed starts to be slow (3.0 sec) is before. When the temperature of the heating member 1 is switched to the temperature for the slow conveyance speed (see FIG. 5B), and the slow conveyance speed (40 mm / sec) is switched to the high conveyance speed (80 mm / sec), the conveyance speed is Since the temperature of the heating member 1 is switched to a temperature for a high conveying speed after the speed is increased (at the time of 1 sec) (see FIG. 5A), the film 1a of the image heating and fixing device 11 and the processing temperature are increased. Although the pressure roller 2 is prevented from being heated to a higher temperature (overheating) than during normal use, the same applies to the overheating of the film 1a and the pressure roller 2 even if the following configuration is adopted. The effect Door can be.
[0099]
That is, when switching the high transport speed to the slow transport speed, the temperature of the heating member 1 is switched to a temperature for the slow transport speed before the transport speed is slow (at 3 sec in FIG. 5B). When switching from a low conveyance speed to a high conveyance speed, a configuration is adopted in which the temperature of the heating member is switched to a temperature for a high conveyance speed after the conveyance speed starts to increase (at 1 sec in FIG. 5A). be able to.
[0101]
[Third Embodiment]
Next, a third embodiment will be described. As the third embodiment, an image heating fixing device used for a laser beam printer having two resolutions of 1200 dpi (process speed 40 mm / sec) and 400 dpi (process speed 120 mm / sec) and the laser beam printer itself are applied.
[0102]
A laser beam printer (hereinafter referred to as LBP) as an image forming apparatus in the present embodiment has a high temperature control mode at a high speed (process speed 120 mm / sec), that is, a temperature control at 400 dpi, and a low speed (process speed). 40 mm / sec), when switching to a low temperature control mode, that is, 1200 dpi, the energization control unit 7a is controlled by the switching control unit 7b of the CPU 7.heaterThe function to turn ON / OFF the power supply to 4 is added, and the low temperature temperature is lower than the LBP that drops from the high temperature temperature control mode to the target temperature in the low temperature control mode while energizing as in the first or second embodiment. The configuration is the same as that of the laser beam printer 16 of the first embodiment except that the mode is switched to the adjustment mode.
[0103]
FIG. 6 shows the resolution for 400 dpi and the resolution for 1200 dpi in the LBP 16 of this embodiment.heaterThe correspondence of each temperature of 4 temperature control modes is shown. Since the LBP 16 of the present embodiment has a high-speed process speed of 120 mm / sec higher than the high-speed process speed of 80 mm / sec of the LBP of the first embodiment, the temperature control mode at a high speed (process speed of 120 mm / sec) Compared with the case of the first embodiment, the temperature control temperature difference corresponding to the two temperature control modes at high speed (process speed 120 mm / sec) and low speed (process speed 40 mm / sec) is higher than that in the first embodiment. Is getting bigger.
[0104]
The switching of the resolution in the LBP 16 of the present embodiment, that is, the procedure of switching the resolution from 1200 dpi to 400 dpi is the same as the LBP procedure of the first embodiment (however, as shown in FIG. 7A) Before transfer after switching the conveyance speed from 40 mm / sec to 120 mm / secroller14, the opening time of the recording material P and the entry time of the recording material P into the fixing nip portion N of the image heating fixing device 11, andheaterEach of the time when the temperature control temperature is switched from the low temperature control to the high temperature control is slightly delayed compared to that in the first embodiment. However, the procedure for switching the resolution from 400 dpi to 1200 dpi is different from the LBP procedure of the first embodiment. This procedure will be described with reference to a sequence chart shown in FIG.
[0105]
7A and 7B, as in the first embodiment described above, the last recording material P on which an unfixed image is formed and supported at a resolution of 400 dpi after the CPU 7 receives the resolution switching signal. Is the origin O of the time for switching between the conveyance speed of the recording material P and the temperature control temperature of the heater.
[0106]
When the last recording material P passes through the fixing nip portion N of the image heating and fixing device 11, the switching control portion 7b of the CPU 7 controls the energization control portion 7a after 0.25 sec from the origin O.heaterTurn off the power to 4 (heater off),heater4 to control energization control unit 7a at 1.25 sec after 1 sec elapsesheater4 starts energization (heater-on), 1.75 sec after origin OheaterThe target temperature of 4 is lowered to a low temperature controlled temperature for 1200 dpi. Then, after 2.5 seconds from the origin O, a command to change the rotation speed of the main motor 10 and change the conveyance speed from 120 mm / sec to 40 mm / sec is issued. The rotation speed of the main motor 10 is stable at 3.25 seconds 0.75 seconds after the output of the conveyance speed switching command signal, and the conveyance speed of the recording material P by the conveyance mechanism C is also stabilized.rollerConnect 14 clutches before transferroller14 opens the recording material P. This recording material P is before transferrollerThe image heating and fixing apparatus 11 is entered in 9.25 seconds after 6.0 seconds from the release of the recording material P 14.
[0107]
As described above, when the laser beam printer 16 of the present embodiment is switched from a high conveyance speed (120 mm / sec) to a low conveyance speed (40 mm / sec), as shown in FIG.heater4, when the temperature control temperature of the heating member 1 is switched, in other words, between the time when the temperature control temperature of the heating member 1 is switched (after 0.25 sec from the origin O) and the time when the slow transfer speed is switched (after 2.5 sec from the origin O) Within the time Tb, the temperature adjustment temperature of the heating member 1 for the high conveyance speed is lowered to the temperature adjustment temperature for the low conveyance speed, so that the influence of the temperature adjustment temperature at the high conveyance speed is imaged at the low conveyance speed. Components such as the film 1a and the pressure roller 2 constituting the heat fixing device 11 are not received.
[0108]
In addition, when switching the slow conveyance speed to the high conveyance speed, as shown in FIG. 7A, a certain time (0) from the time when the switching to the high conveyance speed is completed (after 1.1 sec from the origin O). .9 seconds) After Ta has elapsed,heaterIn other words, since the switching of the temperature adjustment temperature of the heating member 1 to a high conveyance speed is started, the temperature adjustment temperature at the high conveyance speed at the low conveyance speed is started. The components such as the film 1a and the pressure roller 2 constituting the image heating and fixing device 11 are not affected by the above.
[0109]
In this embodiment, as described above,heaterBy switching off the power to 4, temporarily switch to the low-temperature temperature control mode earlier than the LBP to drop from the high-temperature temperature control mode to the target temperature of the low-temperature temperature control mode while energizing as in the first embodiment or the second embodiment With regard to switching the resolution from 400 dpi to 1200 dpi, there is an advantage that switching can be performed faster than in the first embodiment or the second embodiment.
[0110]
As described above, in the present embodiment, when the high conveyance speed (120 mm / sec) is switched to the low conveyance speed (40 mm / sec), the time before the conveyance speed starts to be slow (2.5 sec). When the temperature of the heating member 1 is switched to a temperature for a slow conveyance speed (see FIG. 7B) and the slow conveyance speed (40 mm / sec) is switched to a high conveyance speed (120 mm / sec), the conveyance speed is By switching the temperature of the heating member 1 to a temperature for a high conveyance speed after the speed is increased (at the time of 1 sec) (see FIG. 7A), the film 1a and pressure of the image heating fixing device 11 are changed. Although the roller 2 is prevented from having a higher temperature (overheating) than during normal use, even if the following configuration is adopted, the same applies to the overheating of the film 1a and the pressure roller 2. Gain effect Door can be.
[0111]
That is, when switching the high conveyance speed to the low conveyance speed, the temperature of the heating member 1 is changed to the temperature for the low conveyance speed before the conveyance speed becomes low (at 3.25 sec in FIG. 7B). When switching and switching the slow conveyance speed to the high conveyance speed, the temperature of the heating member is switched to the temperature for the high conveyance speed after the conveyance speed starts to increase (at 0.5 sec in FIG. 7A). A configuration can be employed.
[0113]
The image forming process used in the laser beam printer as the image forming apparatus of the present embodiment is not limited to the electrophotographic image forming process of the embodiment, and any image forming process such as an electrostatic recording process or a magnetic recording process. The recording material (transfer material, photosensitive paper, electrostatic recording paper) is formed and supported on a recording material (transfer material, photosensitive paper, electrostatic recording paper) by means, and an unfixed toner image corresponding to the target image information is formed and supported. It may be an image forming apparatus such as a copying machine which is introduced into the apparatus and thermally fixes the toner image.
[0114]
In addition, the heating device of the film heating system of the present embodiment has a configuration in which an endless belt-like film is suspended between a plurality of members including a heating body (heater) and rotated by a driving unit, and is wound in a roll. A configuration in which a long film at the end is fed out and moved and moved, a heating body may be an electromagnetic induction heating element instead of a ceramic heater, and a film itself may be an electromagnetic induction heating element.
[0116]
As described above, the image heating and fixing apparatus (heating apparatus) and the image forming apparatus according to the present embodiment prevent excessive temperature rise of components in the image heating and fixing apparatus when the process speed is switched. Therefore, it is possible to suppress the deterioration of the constituent members in the image heating and fixing apparatus. Accordingly, the process speed of the image heating apparatus can be changed in a short time, and the resolution of the image forming apparatus can be switched in a short time.
[0117]
【The invention's effect】
  As described above, according to the present invention,When the conveying speed of the member to be heated is switched from the second conveying speed to the first conveying speed that is slower than the second conveying speed, the component is not affected by the temperature at the high second conveying speed, It is possible to prevent the temperature of the film from becoming higher than during normal use.Image heating device andEquipped with the image heating deviceIt was possible to provide an image forming apparatus.
[Brief description of the drawings]
1A is a schematic configuration diagram showing an example of a heating device according to the present invention, and FIG. 1B is a configuration including the heating device shown in FIG. 1A as an image heating fixing device (image heating device). 1 is a schematic configuration diagram showing an example of a laser beam printer as an image forming apparatus according to the present invention.
2A is an enlarged cross-sectional view of a fixing nip portion of the heating apparatus shown in FIG. 1A, and FIG. It is explanatory drawing of arrangement | positioning relationship.
FIG. 3A is a sequence chart of switching from a resolution of 1200 dpi and a process speed of 40 mm / sec to a resolution of 600 dpi and a process speed of 80 mm / sec in the laser beam printer of the first embodiment as an image forming apparatus according to the present invention. (B) is a sequence chart of switching from a resolution of 600 dpi and a process speed of 80 mm / sec to a resolution of 1200 dpi and a process speed of 40 mm / sec in the laser beam printer.
4 shows a laser beam printer shown in FIG. 3 for a resolution of 600 dpi and a resolution of 1200 dpi.heaterIt is explanatory drawing showing the correspondence of each temperature of this temperature control mode.
FIG. 5A is a sequence chart of switching from a resolution of 1200 dpi and a process speed of 40 mm / sec to a resolution of 600 dpi and a process speed of 80 mm / sec in the laser beam printer of the second embodiment as an image forming apparatus according to the present invention. (B) is a sequence chart of switching from a resolution of 600 dpi and a process speed of 80 mm / sec to a resolution of 1200 dpi and a process speed of 40 mm / sec when the gear switching clutch is used in the laser beam printer.
FIG. 6 illustrates a laser beam printer according to a third embodiment as an image forming apparatus according to the present invention for a resolution of 400 dpi and a resolution of 1200 dpi.heaterIt is explanatory drawing showing the correspondence of each temperature of this temperature control mode.
FIG. 7A is a sequence chart of switching from a resolution of 1200 dpi and a process speed of 40 mm / sec to a resolution of 400 dpi and a process speed of 120 mm / sec in the laser beam printer of the third embodiment as an image forming apparatus according to the present invention. (B) is a sequence chart of switching from a resolution of 400 dpi and a process speed of 120 mm / sec to a resolution of 1200 dpi and a process speed of 40 mm / sec in the laser beam printer.
[Explanation of symbols]
1 Heating member
1a Fixing film (film)
2 Elastic pressure roller (pressure member)
4 Heater (heating body)
5 Thermistor (temperature detection member)
7 CPU
7a Energization control unit (means for controlling energization)
7b Switching control unit (switching control means)
11 Heating device (or image heating device)
16 Laser beam printer (image forming device)
20 Image forming means
N Fixing nip (nip)

Claims (2)

A heating member having a heating body that generates heat by energization and a film that moves in contact with the heating body, and the heating body and the pressure member are pressed against each other to form a nip portion; In an image heating apparatus that performs image heating processing on an image on a member to be heated with heat from the heating member by passing through the nip portion,
A transport control means capable of transporting the heated member at a first transport speed and a second transport speed faster than the first transport speed;
A temperature detecting member for detecting a temperature of said heating member,
And a current control means for detecting the temperature from the temperature sensing member to control the energization of the first, first, the heating body such that the second predetermined temperature corresponding to the second transport speed,
The energization control means includes
1) When the heated member is switched from the first conveying speed to the second conveying speed, the heated member becomes the second predetermined temperature after the heated member is switched to the second conveying speed. At the timing, switching from the first predetermined temperature to the second predetermined temperature,
2) When the member to be heated is switched from the second conveyance speed to the first conveyance speed, the heating member is switched to the first predetermined temperature before the member to be heated is switched to the first conveyance speed. An image heating apparatus that switches from the second predetermined temperature to the first predetermined temperature . Image forming means for forming an image on a heating member, and characterized in that it comprises an image heating apparatus according to claim 1, the image image heating processing on heated member, which is conveyed from the image forming means side Image forming apparatus.

Images