JP5325521B2 - Fixing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device that shortens a warm-up time even in use with other drive system and in use of an inexpensive drive source and, moreover, that suppresses non-uniform temperature rise. <P>SOLUTION: The fixing device includes: a pair of pressure rollers 26, serving as rotational bodies, which are disposed opposite to each other so as to form a nip between them, heats transfer paper while conveying the transfer paper sandwiched between them after the transfer of toner, thereby fixing toner; a fixing belt 27; a heat source 30, which heats part of the fixing belt 27 being one of the pair of the rotational bodies 26 and 27; and a control circuit 32, which repeats drive and stop of one of the rotational bodies until the heat source 30 reaches a predetermined temperature from the time when it starts to heat. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a fixing device that fixes a toner image formed on the surface of a transfer paper while conveying the transfer paper through a nip.

  Conventionally, the toner image transferred onto the surface of the transfer paper forms a nip portion for nipping and conveying the transfer paper between the heating body heated to the toner fixing temperature by the heating source and the heating body. Fixing is performed by a fixing device including a pressure roller.

  At this time, as a kind of the heating body, one having a hollow cylindrical heating roller and a heating source such as a halogen heater which is arranged at the center of the heating roller and heats the heating roller substantially uniformly is well known.

  However, in such a heating roller having a heating source disposed therein, the heating roller is increased in diameter, and the entire heating roller is heat-resistant (for example, multilayered) or surface-treated (melted toner at the time of toner fixing) Adhesion prevention treatment) and the like, and not only the warm-up time from the start of heating of the heating source until reaching the predetermined temperature (fixable temperature) is increased, but the heating roller is expensive. There was a problem of becoming.

  Therefore, in recent years, a low-priced and simple layer structure nip forming roller disposed opposite to the pressure roller has been adopted, and a heating roller in which a heating source is disposed inside is used as the nip forming roller. A belt system in which an endless fixing belt is installed between these rollers so as to be rotatable is being adopted.

  In the fixing device in which the nip portion is formed by a pressure roller and a heating roller, and the heating source is arranged in the heating roller, the pressure roller and the heating roller are used until the heating source reaches a predetermined temperature from the start of heating. There is known a technique for shortening the warm-up time by stopping the driving of, thereby reducing the heat transfer to the pressure roller associated with the formation (contact) of the nip portion.

  However, in the belt system using the fixing belt laid between the nip forming roller and the heating roller, the fixing belt in contact with the heating roller is partial with respect to the entire belt circumference, and the thickness of the fixing belt Since the heat capacity is basically small and the heat capacity is small, the heating after stopping the rotation of the fixing belt for a long time (stopping the rotation of each roller) to suppress the heat transfer to the pressure roller side, Damage is likely to occur due to partial overheating of the fixing belt, and there is a possibility of causing a difference in gloss and fixing failure due to temperature unevenness of the fixing belt.

Therefore, in the fixing device using the fixing belt, immediately after the start of heating, the fixing belt is rotated slower than the normal (fixing) driving speed (for example, refer to Patent Documents 1 and 2), or as the detected temperature on the surface of the fixing belt increases. There is known a technique for shortening the warm-up time by adopting such as increasing the linear velocity of the fixing belt (for example, Patent Document 3).
JP 2000-242126 A JP-A-10-213987 JP 2004-286929 A

  However, in the fixing device configured as described above, only the fixing device has a drive source (drive motor) that is driven alone, and the fixing belt is expensive corresponding to a wide linear speed from low speed to high speed. It is realized by adopting a drive motor, and it can be used only when the drive motor is shared with other drive systems of the image forming apparatus, or when it is simply ON / OFF (or full speed and half speed). When a simple drive motor is used, there has been a problem that the drive speed (rotational movement speed) cannot be changed.

  Therefore, in consideration of the above circumstances, the present invention can reduce the warm-up time even when the drive system is shared with another drive system or an inexpensive drive source is used. It is an object of the present invention to provide a fixing device that can suppress generation.

  The fixing device according to the present invention includes a pair of rotating bodies that are disposed to face each other so as to form a nip portion, and which fix the toner by heating the transfer paper while nipping and conveying the transfer paper after toner transfer, and the pair of rotations In a fixing device comprising a heating source for heating one part of the body, the control means for repeatedly driving / stopping the one rotating body from the start of heating of the heating source until reaching a predetermined temperature It is characterized by having.

  Further, the control means sets a drive time and a drive stop time when the drive / drive stop of the one rotating body is repeated so that the drive time becomes longer or the drive stop time becomes shorter as the temperature approaches a predetermined temperature. It is characterized by being changed.

  At this time, the control means may control the switching timing of the stepwise change between the drive time and the drive stop time based on the detection result of the temperature detection sensor that detects the temperature of the one rotating body. The control may be based on the count time of a timer that counts the elapsed time from the start of heating of the heating source.

  The control means may control driving / stopping of the one rotating body by turning on / off a driving motor that rotationally drives the driving side of the pair of rotating bodies, or the pair of rotating bodies. It may be controlled by ON / OFF of a drive transmission clutch disposed in a power transmission system of a drive motor that rotationally drives the drive side.

  The fixing device of the present invention can reduce the warm-up time even when used with another drive system or when an inexpensive drive source is used, and suppresses the occurrence of uneven temperature rise. Can do.

  Next, an image forming apparatus according to an embodiment of the present invention will be described with reference to the drawings.

  1 is an explanatory view of an image forming apparatus equipped with a fixing device according to an embodiment of the present invention, FIG. 2 is an explanatory view of a fixing device according to an embodiment of the present invention, and FIG. 3 is an embodiment of the present invention. FIG. 4 is an explanatory diagram of another fixing device according to an embodiment of the present invention. FIG. 4 is a comparative graph of warm-up time in a control example applied to the fixing device.

(External configuration of image forming apparatus 1)
Referring to FIG. 1, an image forming apparatus 1 according to an embodiment of the present invention includes an automatic document feeder (ADF) that is disposed at the top of an apparatus body 2 and used when reading a document as various functions of a copying machine, a facsimile, and a scanner. 3) and an operation unit 5 for setting / selecting various functions and the like in combination with a display screen 4 such as a liquid crystal monitor disposed on the upper front side of the apparatus main body 2.

  Note that the shape, configuration, function, and the like of the image forming apparatus 1 are not limited to those illustrated. Further, for example, it does not hinder the installation of known optional devices such as ADF 3 and sorter (not shown).

(Internal configuration of image forming apparatus 1)
In addition, the image forming apparatus 1 is disposed below the inside of the apparatus main body 2 so that it can be pulled out from the front of the apparatus main body 2, and a paper feed cassette 6 on which transfer paper (not shown) before printing is stacked and accommodated. In addition to the paper feed cassette 7, the transfer paper loaded and stored in the paper feed cassette 6 is separated and transported one by one from the uppermost one, and provided separately from the paper feed cassette 6 from the side wall surface of the apparatus body 2. A manual feed tray 8 on which transfer paper (not shown) can be stacked and stored, and a manual paper feed transport unit 9 for separating and transporting the transfer paper stacked and stored in the manual feed tray 8 from the top one by one. A paper feed transport unit 10 for transporting transfer paper loaded and stored in an optional paper feed cassette (not shown) installed on the bottom surface of the apparatus main body 2, and each paper feed transport unit 7, 9, 10 An image forming unit 11 for forming an image to be transferred to transfer paper conveyed from A secondary transfer unit 12 that transfers an image formed by the image forming unit 11 to a transfer sheet, and a transfer sheet that is arranged upstream of the secondary transfer unit 12 in the transfer sheet conveyance direction and is conveyed to the secondary transfer unit 12 Registration roller pair 13 for controlling the abutting alignment and conveyance timing, a fixing unit 14 for fixing the toner image after transfer onto the transfer paper, a discharge unit 15 for discharging the transferred transfer paper, and discharging from the discharge unit 15 A stacking unit 16 for stacking the transferred transfer paper after fixing and a reverse path 17 for switching back the transfer paper to the secondary transfer unit 12 when an image is formed on the back surface of the transfer paper are provided.

(Configuration of the image forming unit 11)
The image forming unit 11 irradiates a laser beam L based on image data of a document image read using the ADF 3 or image data included in print data transmitted from an external computer (not shown) or the like. A belt-like intermediate transfer member 19 and a plurality of image forming devices 20 arranged in a tandem manner below the intermediate transfer member 19.

(Intermediate transfer member 19)
The intermediate transfer member 19 is supported by being wound around a plurality of rollers, and is rotated in a predetermined direction by a driving device (not shown) (see an arrow in FIG. 1). The intermediate transfer member 19 is configured by an elastic belt in which a rubber layer is laminated on the surface of a base layer made of synthetic resin or the like.

(Image forming device 20)
The image forming devices 20 are arranged in a row in a tandem manner from the upstream side to the downstream side in the rotational movement direction so as to follow the rotational movement direction of the intermediate transfer body 19. The four image forming devices 20 are arranged in order of magenta, cyan, yellow, and black, for example, in order from the upstream side. These image forming devices 20 include toner containers 21 corresponding to the respective colors. Developer (toner) is replenished. Note that well-known devices are used for the image forming device 20 and the toner container 21, and the present invention is not limited to the illustrated example.

  Each image forming device 20 includes a photosensitive drum 22 on which an electrostatic latent image of a document image is formed by the laser light L irradiated by the exposure device 18, and toner is transferred from the electrostatic latent image to the photosensitive drum 22. The image is developed. Further, the toner image is primarily transferred onto the surface of the intermediate transfer member 19 by a primary transfer unit 23 provided above each image forming device 20. Then, the toner image of each image forming device 20 is transferred to the intermediate transfer body 19 at a predetermined timing by the rotational movement of the intermediate transfer body 19, so that the surface of the intermediate transfer body 19 has magenta A color toner image is formed by superimposing four color toner images of cyan, yellow, and black.

  On the other hand, the secondary transfer unit 12 includes a secondary transfer roller 24, and the color toner image formed on the surface of the intermediate transfer member 19 is transferred to the nip of the transfer paper accompanying the press contact between the intermediate transfer member 19 and the secondary transfer roller 24. The image is transferred onto the surface of the transfer paper by applying a transfer bias during conveyance.

  At this time, deposits such as unfixed toner remaining on the surface of the intermediate transfer member 19 after the secondary transfer are cleaned by the cleaning device 25 disposed on the side opposite to the secondary transfer unit 12.

(Fixing unit 14)
The fixing unit 14 fixes the unfixed toner image formed on the transfer paper by heating and pressurizing while transferring the transfer paper on which the unfixed toner image is formed in the secondary transfer unit 12 by nip. As shown in FIG. 2, the pressure roller 26, the fixing roller 28 disposed so as to face the pressure roller 26 through the endless fixing belt 27, and the fixing belt 27 are rotated together with the fixing roller 28. A heating roller 29 and a heating source (for example, a halogen heater) 30 disposed inside the heating roller 29 are provided.

(Configuration of fixing belt 27)
The fixing belt 27 is wound around the fixing roller 28 and the heating roller 29 and is rotated in the direction of the arrow in the figure by the rotational driving of the pressure roller 26. The fixing belt 27 employed here is an endless belt such as a nickel thin plate, for example, and an outer peripheral surface is coated with an offset preventing agent such as a silicon rubber film. Further, the surface temperature of the fixing belt 27 is monitored by the temperature detection sensor 31, and the detection result is output to the control circuit 32.

(Configuration of rollers 26, 28, 29)
The fixing roller 28 and the pressure roller 26 are rubber rollers arranged to face each other, and the pressure roller 26 is pressed toward the center of the fixing roller 28 via the fixing belt 27 to form a nip portion. . The heating roller 29 applies tension to the fixing belt 27 and is formed of a cylindrical aluminum tube having a constant thickness in the axial direction. In addition, the fixing belt 27 is heated to a predetermined temperature (for example, a fixing temperature) through the heating roller 29 by the heat generated by the heating source 30 disposed inside the heating roller 29.

(Function of control circuit 32)
The control circuit 32 executes the heating control based on the control program related to the heating control according to the present invention stored in the ROM 33. The ROM 33 stores various control programs related to the entire image forming process, and the control circuit 32 and the ROM 33 constitute a microcomputer that executes the heating control according to the present invention.

  The control circuit 32 controls the driving of the heater driver 35 that turns on / off the heating source 30 when the main power supply 34 is turned on or a known sleep mode (standby mode / energy saving mode) is released. To do.

  At this time, the control circuit 32 counts the detection result from the temperature detection sensor 31 that detects the surface temperature of the fixing belt 27 and the timer 36 that counts the heating time of the heating source 30 from turning on the main power supply 34 or releasing the sleep mode. The rotation of the pressure roller 26 is driven by a motor driver 37 of a drive motor (not shown) that drives the pressure roller 26 based on the count time, or the drive motor or other drive motor. The driving of the clutch driver 38 for turning on / off the clutch arranged in the drive system for transmitting power is controlled.

  Specifically, when the main power supply 34 is turned on or the sleep mode is canceled, the control circuit 32 starts heating the heating source 30 (controls the heater driver 35 to be ON).

  At this time, the control circuit 32 controls the motor driver 37 or the clutch driver 38 to be OFF to stop the rotation driving of the pressure roller 26, that is, the rotational movement of the fixing belt 27, and the heating roller 27 is fixed to the fixing belt 27. Only a part of the area (near the contact area) is heated.

  As a result, since the amount of heat transferred to the pressure roller 26 decreases while the rotation of the fixing belt 27 is stopped, the amount of heat held by the fixing belt 27 increases with respect to the amount of heat (heat generation amount) of the heating source 30. .

  As the rotation stop time of the fixing belt 27 increases, the amount of heat held by the fixing belt 27 increases and the temperature rising speed increases. However, the rotation movement also occurs in the vicinity of the contact portion between the heating roller 29 and the fixing belt 27. Therefore, when the sheet is passed as it is, the transfer sheet reaches the nip portion. Temperature unevenness cannot be solved.

  Therefore, the control circuit 32 uses the count time of the timer 36 to turn off the motor driver 37 or the clutch driver 38 after a predetermined time has elapsed, and thereafter controls the motor driver 37 or the clutch driver 38 to be turned off / on. To do.

  At this time, the actual rotational movement time and rotational movement stop time of the fixing belt 27 take into consideration the time (for example, 3 seconds) that the fixing belt 27 makes one revolution at a predetermined (fixing) peripheral speed. It is desirable that the contact location between the fixing belt 27 and the heating roller 29 is set to be different each time the rotation of the fixing belt 27 is stopped.

  The rotational movement time and the rotational movement stop time of the fixing belt 27 correspond to the detected temperature result of the temperature detection sensor 31, that is, as the detected temperature becomes higher (approaching the predetermined temperature), the rotational movement time. May be lengthened or the rotational movement stop time may be shortened.

  FIG. 3 shows that when the rotation of the fixing belt 27 is not stopped from the start of warm-up until the predetermined temperature is reached (chain line in the figure), the fixing belt 27 is rotated for two seconds from the start of warm-up until the predetermined temperature is reached. In the case where the operation of stopping for 1 second is alternately performed (two-dot chain line in the figure), the fixing belt 27 is rotated for 2 seconds from the start of warm-up until reaching a predetermined temperature, and then the operation of stopping for 2 seconds is performed alternately. When the fixing belt 27 is rotated for 1 second from the start of warm-up until the predetermined temperature is reached, the operation of stopping for 1 second is alternately performed (solid line in the figure) at the actual machine level. The time required to reach the fixable temperature (140 ° C.) as the predetermined temperature when performing is shown.

  As shown in FIG. 3, when the heating control of the present invention is performed, the warm-up time can be shortened as compared with the case where the rotation of the fixing belt 27 is not stopped at all.

  When the clutch driver 38 is ON / OFF controlled, it is possible to contribute to facilitating the releasing operation work when a jam occurs in the nip portion of the fixing device 14 by turning off the clutch at the time of jam. .

  Further, in the above-described embodiment, the case where it is applied to the so-called roller-belt type fixing device 14 has been described. For example, as shown in FIG. 4, the pressure roller 26 and the fixing roller 28 are brought into direct pressure contact with each other. In the case where a part of the fixing roller 28 is partially heated by a heating source 39 such as an IH heater or the so-called external heating type in which the heating roller is brought into direct contact with the fixing roller or belt from the outside, at least the heating source is heated. The present invention can be effective for all fixing devices that employ a heating method that is partial.

  In the above embodiment, the image forming apparatus of the present invention is applied to a full-color multifunction peripheral. However, for example, the image forming apparatus can be applied to all image forming apparatuses such as a monochrome multifunction peripheral and a single-color printer. Of course you can.

  In the above-described embodiment, the control circuit 32 discloses that the driving / stopping of the fixing belt 27 is repeated from the start of heating of the heating source 30 until the predetermined temperature is reached. It may be controlled by the heating control program software itself.

1 is an explanatory diagram of an image forming apparatus equipped with a fixing device according to an embodiment of the present invention. 1 is an explanatory diagram of a fixing device according to an embodiment of the present invention. FIG. FIG. 6 is a comparative graph of warm-up time in a control example applied to the fixing device according to the embodiment of the present invention. It is explanatory drawing of the other fixing apparatus which concerns on one Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 14 ... Fixing device 26 ... Pressure roller 27 ... Fixing belt 28 ... Fixing roller 29 ... Heating roller 30 ... Heating source 31 ... Temperature detection sensor 32 ... Control circuit (control means)

Claims (5)

A pair of rotating bodies that are arranged to face each other so as to form a nip portion, hold the transfer sheet after toner transfer and heat the transfer sheet to fix the toner, and a part of one of the pair of rotating bodies A fixing device including a heating source for heating,
A control means for repeatedly driving / stopping the one rotating body between the start of heating of the heating source and the arrival of a predetermined temperature ;
The control means sets the drive time and drive stop time when repeating the drive / drive stop of the one rotating body in a stepwise manner so that the drive time becomes longer or the drive stop time becomes shorter as the temperature approaches a predetermined temperature. the fixing device according to claim Rukoto varied. The control means, the switching timing of the step change between the drive time and drive stop time, you and controls based on the detection result of the temperature detection sensor for detecting the temperature of the one of the rotary body according Item 4. The fixing device according to Item 1. The control means, the switching timing of the step change between the drive time and drive stop time, characterized that you control in accordance with the timer count time of counting the elapsed time from the start of heating of the heating source The fixing device according to claim 1 . The control means, the driving / driving stop of the one rotary member, according to claim 1 to claim 3, characterized in that controlled by ON / OFF of a driving motor for rotationally driving the driving side of the pair of rotating bodies The fixing device according to any one of the above. The control means controls driving / stopping of the one rotating body by ON / OFF of a driving transmission clutch disposed in a power transmission system of a driving motor that rotationally drives the driving side of the pair of rotating bodies. the fixing device according to any one of claims 1 to 3, characterized in.

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