JPH1124484A - Fixing device - Google Patents

Abstract

(57) [Summary] (with correction) [PROBLEMS] In a web-type cleaning mechanism, cleaning of a heating roller using a web is performed only during a copying operation (during operation of a fixing device), and is in a standby state (during a stop). (2) to prevent the toner and the like sandwiched between the web and the heating roller from being generated due to the fact that the heating roller has not been cooled, and to prevent the surface of the heating roller from being damaged by the cooled toner and the like. SOLUTION: In a state in which a pressure roller 2 is pressed against a peripheral surface of a heating roller provided with a heater 3, a transfer paper holding an unfixed toner image is passed through a nip portion of both rollers, thereby forming a toner image. The fixing device, which has a web-type cleaning mechanism for feeding the web toward the peripheral surface of the heating roller, the cleaning device terminates a series of fixing jobs by the fixing device. Each time, a new portion of the web is sent to the peripheral surface of the heating roller to perform a web winding operation for cleaning.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic copying machine,
The present invention relates to an improvement of a fixing device used in an image forming apparatus such as a printer and a facsimile machine, and more particularly, to an improvement of a web-type cleaning mechanism used for cleaning a surface of a heating roller constituting a fixing device.

[0002]

2. Description of the Related Art In an electrophotographic image forming apparatus,
First, an electrostatic latent image is formed by irradiating optical image information such as reflected light of an original onto a photoreceptor uniformly charged in advance, thereby eliminating charges according to the amount of exposure light. continue,
The toner image formed by attaching toner to the electrostatic latent image is transferred onto a transfer sheet, and then the transfer sheet is conveyed to a fixing device and pressed while heating to transfer the toner image onto the transfer sheet. Establish. The heat roller fixing device includes a heating roller having a heater therein, and a pressure roller that rotates while being pressed against the peripheral surface of the heating roller,
This is a means for thermally fixing the toner image by passing the transfer paper holding the unfixed toner image through the nip portion of both rollers. By the way, since the peripheral surface of the heating roller is in contact with the toner image on the transfer paper, the peripheral surface of the heating roller may be coated with a fluororesin layer or the like having good releasability so as to prevent adhesion of foreign substances such as toner and paper powder. However, in practice, it is not possible to completely prevent adhesion of toner and the like. Especially,
If the set temperature of the heating roller is too high, for example, an offset phenomenon occurs in which the toner that has once adhered on the transfer paper peels off and adheres to the heating roller side. If toner or the like adheres and accumulates on the peripheral surface of the heating roller, a decrease in fixing performance, further accumulation of toner adherence, and the like occur, which causes deterioration in image quality. For this reason, conventionally, various methods for appropriately cleaning the peripheral surface of the heating roller have been proposed. For example, there has been known a cleaning device provided with a cleaning mechanism that applies oil to a heating roller to enhance releasability and removes foreign matter such as toner attached thereto. As a cleaning device of this type, generally, a roller system in which a cleaning member made of a roller is brought into contact with a peripheral surface of a heating roller, a felt system in which a cleaning member made of felt is slidably contacted with a heating roller, and further, a web wound around a delivery roller There is known a web system or the like in which the peripheral surface of a heating roller is cleaned by a web in a process of winding the heating roller by a winding roller. Among these, the performance of the web cleaning method is superior to other methods,
In recent years, it has been widely used.

A web-type cleaning mechanism fixes one end of a web to a take-up roller and sends the other end to a delivery roller and winds the web, and presses the web by a pressing member provided between the two rollers. The dirt on the peripheral surface of the heating roller is wiped off by being pressed against the heating roller. Further, oil is applied by impregnating the web with an offset prevention liquid such as silicone oil. Then, by rotating the winding roller by a driving device such as a motor and winding the web, the new web surface always presses against the heating roller surface, so that the cleaning performance of the web does not deteriorate with time.
The web feed speed and feed interval are determined by the number of copies, image density, and the like. Next, in recent image forming apparatuses, in order to reduce power consumption, the fixing set temperature during standby in the energy saving mode is set lower than the fixing set temperature during copying operation, or the fixing heater is turned off during standby. It has become. On the other hand, in the conventional web-type cleaning mechanism, the web winding operation is performed only during copying, and is not performed during standby. Therefore, during standby, the dirt such as offset toner and paper dust sandwiched between the surface of the heating roller and the web is cooled and solidified due to the temperature decrease of the heating roller in the energy saving mode. Even if the heating roller starts to rotate in the next copying operation or the like,
It is not warmed enough to soften and rubs with the web damaging the release layer on the heated roller surface. Such flaws further cause image stains such as offsets, so that image quality deteriorates. Further, in a conventional web-type cleaning mechanism, the web winding operation is performed intermittently, the temperature of the heating roller is detected by a sensor, and the web operation is intermittently performed based on the detected temperature data. There is a known technique (Japanese Patent Application Laid-Open No. 58-145977, "Cleaning mechanism", and Japanese Patent Application Laid-Open No. 58-205179, "Image forming apparatus"). However, conventionally, since the control for switching the web winding interval was not performed while considering the temperature condition of the pressure roller, under the condition of the first time in the morning when the fixing unit was not sufficiently warm, The temperature of the roller is not stable (the heat capacity is so large that only the nip that is in long contact with the heating roller warms up), so under the first conditions in the morning, the fixability decreases and the offset toner to the heating roller increases. There was a problem.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and in a web-type cleaning mechanism, cleaning of a heating roller using a web is performed only during a copying operation (during operation of a fixing device). The cooling of the toner and the like sandwiched between the web and the heating roller and the heating of the heating roller by the cooled toner and the like have occurred due to the fact that the cooling was not performed during the standby (during the stop). The purpose is to prevent surface damage. Another object of the present invention is to solve the problems of a decrease in fixability and an increase in offset toner, which are likely to occur when the temperature of the pressure roller is not sufficiently raised, such as the first time in the morning. That is, since the web winding operation is performed every time the copying operation is completed, when the operation is resumed after the standby, the nip portion between the heating roller and the web has no stain such as toner or paper dust. State. Thus, even when the temperature of the heating roller is lowered during standby in the energy saving mode, an object of the present invention is to prevent the release layer on the heating roller from being damaged and to prevent the image quality from deteriorating. According to a second aspect of the present invention, the web winding operation is performed only when the temperature of the heating roller becomes equal to or lower than a preset temperature in the energy saving mode after the end of the copying operation. An object of the present invention is to reduce the number of web winding operations and extend the life of the web without damaging the release layer. Claim 3
The invention has two web winding intervals during copying operation, one of the web winding interval t _A when the temperature of the pressure roller is stable, unstable temperature of the other pressure roller The web winding interval at time t _B, and the relationship between the intervals is t
With _A> t _B, reduces the fixability morning most conditions, even if the offset toner to the heating roller is increased, the heating roller and the dirt of the toner and paper dust overflowing from the nip portion of the web An object of the present invention is to prevent the image from passing through and deteriorating the image quality.

[0005]

In order to achieve the above object,
According to the first aspect of the present invention, the transfer paper holding the unfixed toner image is passed through the nip portion of both rollers in a state where the pressure roller is pressed against the peripheral surface of the heating roller provided with the heater, so that the toner is In a fixing device for fixing an image, which is provided with a web-type cleaning mechanism for feeding a web toward a peripheral surface of a heating roller, the cleaning mechanism terminates a series of fixing jobs by the fixing device. Each time a new portion of the web is sent to the peripheral surface of the heating roller, a web winding operation for cleaning is performed. According to a second aspect of the present invention, in a state in which a pressure roller is pressed against the peripheral surface of a heating roller provided with a heater, a transfer paper holding an unfixed toner image is passed through a nip portion between the two rollers, so that toner is transferred. In a fixing device for fixing an image, which is provided with a web-type cleaning mechanism for feeding a web toward a peripheral surface of a heating roller, the cleaning mechanism terminates a series of fixing jobs by the fixing device. Then, when the temperature of the heating roller becomes equal to or lower than a preset temperature, the web winding operation is performed. The invention of claim 3 is
A fixing device that fixes a toner image by passing a transfer paper holding an unfixed toner image through a nip portion of both rollers in a state in which a pressure roller is pressed against a peripheral surface of a heating roller having a heater. A web-type cleaning mechanism for feeding the web toward the peripheral surface of the heating roller, wherein two types of web winding intervals are provided in intermittent web winding operation during a copying operation; the web winding interval is the web winding interval t _a when the temperature of the pressure roller is stable, the other web winding interval when the temperature is unstable in the pressure roller a web winding interval t _B age,
The relationship between the two winding intervals is set so that t _A > t _B.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to embodiments shown in the drawings. FIG. 1 is a schematic configuration diagram of a heat roller fixing device using a web-type cleaning mechanism as one embodiment of the present invention. A pressure roller 2 having an elastic body surface is pressed against a heating roller 1 heated by a heater 3, and the transfer paper 4 holding an unfixed image 5 passes between the rollers 1 and 2, thereby performing fixing. Will be A web-type cleaning mechanism 6 is added to the heating roller 1 in order to apply oil such as silicone oil for improving releasability to the surface of the heating roller 1 and to clean foreign matters on the surface of the heating roller 1. The surface temperature (fixing temperature) of the heating roller 1 is detected by temperature detecting means 7 such as a thermistor, and a control unit (CPU, RO,
(M, RAM, I / O port) 10 turns on / off the motor 3 to maintain the fixing temperature at a constant temperature. One end of the web 61 is fixed to the winding member 63, and the other end is wound around the sending member 64. The take-up member 63 is driven to rotate by a driving device (motor) 66 and gradually takes up the web 61 wound around the delivery member 64. An elastic pressing member 62 located between the winding member 63 and the delivery member 64 presses the web 61 against the heating roller 1 by the pressing member 65, so that the web 61 applies oil to the surface of the heating roller 1. And remove foreign substances adhering thereto. The web is made of a material that can be impregnated with oil. The control unit 10 controls the drive motor 11 of the heating roller 1, the heater 3, the drive device 66, and the like.

When the electrophotographic copying machine has the energy saving mode, the copying machine enters the energy saving mode after copying is completed. In this case, the heater is controlled by setting the temperature of the heating roller 1 lower than the temperature set during copying. And a method in which the heater 3 is not turned on at all. As a method of lowering the set temperature of the heating roller, there is a method of shortening the lighting time of the heater 3 or, when there are a plurality of heaters, reducing the number of heaters to be lit to reduce power consumption. Next, the winding operation of the web 61 during the copying operation is changed depending on the type and state of the copying machine. For example, the winding operation of the web 61 during the copying operation includes continuous winding and intermittent winding. In the case of intermittent winding, the winding operation is performed every fixed number of copies or when the heating roller 1 and the pressing member are pressed. The web 61 is wound up at a constant rotation speed such as 62 (pressing roller). Further, the web winding speed, the winding amount, and the winding interval are as follows: the temperature fixing property of the heating roller, the amount of the offset toner,
An optimal value is set according to conditions such as an image. First of the present invention
In the embodiment, since the control unit 10 operates the motor 66 to perform the web winding operation every time the copy operation is completed (each time one job is completed = each time the operation of the fixing device is completed), the operation after the completion of one job is performed. When the operation is resumed after the standby is completed, it is possible to set a state in which no dirt such as toner or paper dust exists in the nip portion between the heating roller 1 and the web 61. As a result, even when the surface temperature of the heating roller is lowered during standby in the energy saving mode, the release layer on the heating roller surface is not damaged, and a decrease in image quality can be prevented. The winding amount of the web is set in advance so as to be an appropriate amount. In other words, every time the fixing device finishes a series of fixing jobs, a new portion of the web is sent out to the peripheral surface of the heating roller to perform cleaning. It is possible to prevent foreign matters such as toner sandwiched between the web and the peripheral surface of the heating roller from causing a situation such as damaging the surface of the heating roller when the operation is resumed.

Next, in the second embodiment of the present invention, after the completion of all the copying operations of one job, only when the temperature of the heating roller becomes equal to or lower than a preset temperature in the energy saving mode, the web is not printed. By performing the winding operation, the release layer on the surface of the heating roller is not damaged, the number of web winding operations is reduced, and the life of the web is extended. That is, in this embodiment, when the entire copy operation in one job is completed, the control unit controls the driving device 66 to wind the web 61 by a predetermined amount. Rather than performing winding, it is determined whether or not cleaning is required, and based on the determination result, winding is performed only when necessary. That is, the web is wound in this embodiment only when the temperature of the heating roller 1 becomes equal to or lower than a preset temperature immediately after the end of the copying operation. As a result, when the temperature of the heating roller detected by the temperature detecting means 7 is maintained at such a high temperature that the toner is not likely to be cooled and solidified, the winding operation is not performed and the web is used. The amount can be suppressed.

In the third embodiment of the present invention, in the intermittent winding operation of the web during the copying operation, two types of winding intervals are provided, and one of the winding intervals is used to stabilize the temperature of the pressure roller. web winding the interval t _a, the other winding web winding interval t when the temperature is unstable intervals the pressure roller when there
And _B, and the relationship of each interval, by the t _A> t _B, decreases the fixability under the conditions in the morning most of the time zones,
Even when there is a possibility that the amount of offset toner to the heating roller may increase, it is possible to prevent the toner from overflowing from the nip portion between the heating roller 1 and the web 61, to prevent the dirt such as toner and paper dust from slipping, and to improve the image quality. We try to prevent quality deterioration.

That is, when the power of the image forming apparatus is turned on in the first time zone in the morning as described above, even if the heater of the heating roller generates heat, the pressure roller is partially (the nip with the heating roller). Part), the temperature has not been raised sufficiently.
When the temperature of the pressure roller is not stable,
When the fixing device is operated, there is a problem that the fixing property is reduced and the amount of offset toner to the heating roller is increased.
For this reason, according to the present invention, the web 61 in the case where the copy operation is performed within a preset time (time during which the temperature of the pressure roller is insufficiently increased) after power supply to the heater 3 starts at the beginning of the morning. Winding interval t _B in the intermittent operation of
Web 61 when copying operation is performed after that time
By setting the relationship with the winding interval t _A to t _A > t _B , the frequency of cleaning by the web at a stage where the temperature of the pressure roller is insufficient is increased, and the cleaning effect is enhanced. Moreover, in this embodiment, the temperature detecting means of the pressure roller 2 is not added, but the operation of measuring a certain time after the power is supplied to the heater and the operation of winding the web during the copying operation within the certain time By only adding or changing the control of shortening the interval, efficient cleaning can be realized, so that the configuration can be prevented from becoming complicated.

[0011]

As described above, according to the first aspect of the present invention, the web winding operation is performed each time the copying operation is completed. Therefore, when the operation is resumed after the standby, the toner is added to the nip portion between the heating roller and the web. And no dust such as paper dust. As a result, even when the temperature of the heating roller drops during standby in the energy saving mode or the like, it is possible to prevent the release layer on the surface of the heating roller from being damaged, and to prevent deterioration in image quality. According to a second aspect of the present invention, the web winding operation is performed only when the temperature of the heating roller becomes equal to or lower than a preset temperature in the energy saving mode after the end of the copying operation. It is possible to reduce the number of web winding operations and extend the life of the web without damaging the release layer. The invention according to claim 3 has two types of web winding intervals during the copying operation,
One of the temperature of the pressure roller and the web winding interval t _A when stable, the other was a web winding interval t _B when the temperature of the pressure roller is unstable, the relationship of each interval, t _A >
With t _B, a reduced fixing property in the morning most conditions, even if the offset toner to the heating roller is increased, slipping dirt toner and paper dust overflowing from the nip portion of the heating roller and the web It does not occur and does not lower the image quality. Further, since there is no need to provide a temperature detecting means such as a thermistor on the pressure roller side, the configuration is simple.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a fixing device using a web-type cleaning mechanism according to an embodiment of the present invention.

[Explanation of symbols]

1 ... heating roller, 2 ... pressure roller, 3 ... heater,
4 transfer paper, 5 unfixed image, 6 web device,
7 ... Temperature detection means, 10 ... Control part, 11 ... Motor, 61 ... Web, 62 ... Pressing member, 63 ... Winding member, 64 ... Support member, 65 ... Pressing members, 66
・ Drive unit

Claims (3)

[Claims] 1. A transfer sheet holding an unfixed toner image is passed through a nip portion of both rollers in a state in which a pressure roller is pressed against the peripheral surface of a heating roller provided with a heater, thereby forming a toner image. In a fixing device that performs fixing, provided with a web-type cleaning mechanism that sends a web toward a peripheral surface of a heating roller, the cleaning mechanism is configured such that the fixing device completes a series of fixing jobs. A fixing device configured to execute a web winding operation for cleaning by sending a new portion of the web to a peripheral surface of the heating roller. 2. A transfer paper holding an unfixed toner image is passed through a nip portion of both rollers in a state where a pressure roller is pressed against a peripheral surface of a heating roller provided with a heater, thereby forming a toner image. In a fixing device that performs fixing, which includes a web-type cleaning mechanism that sends a web toward a peripheral surface of a heating roller, the cleaning mechanism terminates a series of fixing jobs by the fixing device, A fixing device, wherein when the temperature of the heating roller becomes equal to or lower than a preset temperature, the web winding operation is performed. 3. A transfer paper holding an unfixed toner image is passed through a nip portion of both rollers in a state in which a pressure roller is pressed against a peripheral surface of a heating roller provided with a heater, thereby forming a toner image. In a fixing device for performing fixing, which is provided with a web-type cleaning mechanism for feeding a web toward a peripheral surface of a heating roller, a web winding interval in an intermittent web winding operation during a copying operation is set. two provided, one of the temperature of the pressure roller a web winding interval to the web take-up interval t _a when stable, web and other web winding interval when the temperature of the pressure roller is unstable fixing device and a winding interval t _B, the relationship of the two winding spacing, characterized in that set to be t _a> t _B.