JPS60196787A - Fixing device - Google Patents

Abstract

PURPOSE:To obtain picture recording of good quality without offset for a long period by pressing a blank paper to the surface of a roll of a fixing device and carrying it each time when the number of processed papers reaches a certain value and facilitating cleaning the surface of the roll. CONSTITUTION:Control programs for the whole of a copying machine including control programs related to the cleaning cycle of the fixing device are stored in a ROM14 and are read out by a CPU12 and are executed one by one. Before the cleaning blank paper is fed in the cleaning cycle, a tray where the longest form in the axial direction of a heat fixing roll is set is selected for the purpose of maximizing the cleaning area of a fixing device 19, and an electrifier 20 and a developing device 21 are turned off to start the copying cycle. Consequently, the form from the tray reaches the fixing device 19 in the state where a toner image is not put on this form, and this form is pressed and carried by the heat fixing roll and a pressuring roll of the fixing device 19 to clean the surfaces of rolls.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fixing device using a roll, and particularly to cleaning dirt on the surface of the roll.

[Prior art]

In devices that utilize an electrophotographic process, such as electrophotographic copying machines, facsimiles, and printers, fixing processing is performed at the final stage of a series of processes for obtaining image records such as copies. Generally, a toner image formed on a photoreceptor is transferred onto a recording support, such as paper, by a transfer device, and then in a fixing step, the toner image is fixed on the surface of the recording support, and the toner image is discharged outside the machine.

The fixing device keeps the toner image formed on the recording support in a stable state before it is fixed, but it is not fixed and can be removed if touched. As a method for fixing the toner image, a heat fixing method in which the toner is melted by heating and fixed on the recording support is widely adopted in the above-mentioned devices. Among these, devices using a heat roll fixing method apply constant pressure between a pair of rolls, at least one of which is heated, and fix the toner by passing it through a recording support carrying an unfixed toner image. Compared to other hot-air fixing methods that do not require conveyance, oven fixing methods, etc., this method uses less power, is advantageous for faster speeds, and has the advantage of reducing the risk of fire due to clogging of the recording support in the fixing unit. This is the most common.

By the way, in a fixing device that uses this type of roll, when fixing a toner image on a recording support such as paper, the roll and the toner image come into contact, so some of the toner is transferred to the roll. Contamination on the roll surface, for example, the trailing edge of the same sheet of paper, or an offset phenomenon in which the sheet is retransferred and fixed on the next sheet of paper, may occur.

Therefore, the following measures have been taken to prevent this. Zunaiji uses a heat fixing roll whose surface is coated with a heat-resistant release material such as polytetrafluoroethylene (trade name: Teflon) or silicone rubber. The roll is made of a heat-resistant material such as silicone rubber or fluoro rubber in order to have a bump in the contact width when it comes into pressure contact with the heat-fixing roll, but the above-mentioned offset phenomenon occurs. In order to prevent this, a release agent such as silicone oil is generally applied to the surface of at least one roll. However, in the case of this method, the applicator that supplies the release material is complicated, leading to an increase in the size of the fixing device, and the release material may conversely stain the paper or cause the release material to spill. There is a risk of an accident occurring. As described above, this method has the disadvantage of causing other problems as described in 1. In particular, troubles caused by the use of the mold release material account for a proportion of troubles in the entire fixing section, and approximately The percentage is as high as 80%.

Also, recently, in order to eliminate the need for supplying mold release material as mentioned above,! The development of i1 (excellent moldability) toner is underway, and it is hoped that toner adhesion to heat fixing rolls and pressure rolls will be improved by using such toners with improved mold release properties. However, when a heat-resistant elastic material such as silicone rubber is used for the heat-fixing roll, it is not possible to completely prevent the above-mentioned offset phenomenon simply by improving the toner, and the number of sheets processed, that is, the number of copies made by a copying machine, increases. If the number of sheets exceeds about 50,000 sheets, an offset phenomenon will still occur, and the problem of retransfer to the recording support as described above will not be resolved, making it impossible to obtain image records of consistent quality over a long period of time. .

As described above, all of the above-mentioned preventive measures have problems, especially in high-speed copying machines, etc., which increase the number of troubles, increase maintenance costs, and cause inconvenience to users.

[Purpose of the invention]

This invention was made in view of the above points, and utilizes an electrophotographic process in which a recording support such as paper is passed through the machine and discharged without attaching a special cleaning device to the roll. The object of the present invention is to make it possible to easily clean the roll surface by effectively utilizing the operation of the equipment, and to obtain good quality image recording without offset over a long period of time.

[Structure of the invention]

In order to achieve the above object, the present invention cleans the roll surface of the fuser by cleaning a sheet of blank paper every time the number of sheets processed reaches a certain number or every time the processing start operation reaches a certain number of times. The rolls are used to transport the paper at a pressure of JfR.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 shows a mechanism of a fixing device portion of a fixing device using a roll to which the present invention can be applied. The heat fixing roll (1) consists of a cylindrical core metal (2) and a cylindrical core metal (2).
A coating layer (3) made of a heat-resistant elastic material covers the surface of the roll, and a coating layer (4) is provided inside the roll. The cork lamp (4) can be controlled to heat the heat-fixing roll (1) so that the surface temperature of the heat-fixing roll (1) reaches a predetermined temperature required in the fixing process, for example, 189°C. On the other hand, a temperature detection device (5) using a thermistor or the like is provided around the heat fixing roll (1) to detect the surface temperature in accordance with such temperature control. The pressure roll (6), which is paired with the heat fixing roll (1) and passes the recording support between them as will be described later, has a rod-shaped or cylindrical core bar covered with a heat-resistant elastic material having appropriate elasticity. The heat fixing roll (1) and the pressure roll (1) are in contact with each other.
A fixing nip is formed by both of 6).

At the end of the fixing nip, a paper guide (
9) and a paper guide (11) for sending out the paper (8) which is conveyed under pressure between the rolls (1), (6) and is further separated by the separating claw (lO).
) is provided, and when a paper (8) having the above-mentioned toner image (7) is fed through the above-mentioned step 1, the toner image (7) on the paper (8) is When passing through the fixing nip between the heating roll (1) heated to a predetermined temperature by the Kortz lamp (4) and the pressure roll (6), it melts and flows into the fibers of the paper (8), and then It cools and solidifies, creating a stable, permanently fixed image.

In this way, the paper (8) on which the toner image (7) is formed
) is conveyed under pressure by a heating fixing roll (1) and a pressure roll (6), so that the toner image (7) is transferred to the paper (8).
Heat fixing is performed.

FIGS. 2 and 3 show an example of the configuration of a control system and its control @1 operation according to an embodiment of the present invention. A case is shown in which the surface of the roll of the fixing device is cleaned by rolling three sheets of blank paper every time the number of sheets reaches 10,000.

In Figure 2, 02) is the central processing unit (CPU), 0
3) is random access memory (RAM), (1
This ROM04 is a 414t read own only memory (ROM), and the mechanical control program for the entire copying machine, including the control program for the cleaning cycle of the fuser as shown in the flowchart in FIG. 3, is fixedly stored in the ROM04. ,
When the power is turned on, this is read from the beginning by the CPU (121) and executed one by one. (15) is a read/write that retains its own memory contents by the external batch even if the control system power is turned off. Possible Non-Volatile Memory (17
1 is an input/output controller that directly turns on/off external devices according to commands from the CPU (12), reads data from the outside, and transfers it to the CPU (121). In addition to the failure history of the machine body and control information specific to the machine, the data memory 05) stores information used in the control program shown in Fig. 3, as shown below by extracting a part of the contents. It has become so.

Contents (excerpt) of non-volatile memo January 15) CONT TE
MP 189°C Fuser control temperature during normal copy cycle CLEAN TEMP 220°C Fuser control temperature during cleaning cycle FUSERCV Number of copies per copy after fuser cleaning FUIRD
UTY 40,000 sheets Number of copies that require cleaning of the fuser unit FEED CNT 8 sheets Number of blank sheets fed when cleaning the fuser unit The above FUSERDUTY is written in a certain number of copies at the time of machine shipment or by a service person in April in this example. , FEED CNT is similarly set to a fixed number of one or more sheets, which is three in this example. Further F
As for USERCV, as mentioned above, the number of copies made during normal copying operations is accumulated and stored even if the power is turned off, and is cleared to "0" when the fuser cleaning cycle is completed. be done.

The operator console (181), the fuser (
19), charger (2)), developer ■υ, and other equipment), the operator console (for the old one)
It is equipped with an operation section such as a print start button for starting copying, a display section for displaying the set number of copies, main paper tray selection and size, paper replenishment, etc., and also lights up in the case of a cleaning cycle as described later. ``Please wait'' is equipped with a clamp. The fixing device (191) has a mechanism similar to that shown in FIG. 1, and the charging device (4) and developing device Qη are controlled to be turned off during the cleaning cycle.

Next, referring to FIG. 8, the operation of cleaning the roll surface of the fixing device (19) will be described.

When the control system is powered on, the CPU [21] is reset and processing starts from the first address of the ROM (141).

First, check the contents of ROM04, check the write/read of RAM (131), input/output control 0?
), initialize the hardware such as mode settings, and use the operator console display to copy one copy per copy.
Displays initial setting data such as main paper tray selection and size display.

Next, it is determined whether there is any paper or not, and temperature control of the fixing device Q9) is started. If you check the paper tray,
When there is no paper in any of the trays, the "paper replenishment" lamp on the operator console 08) is lit to prompt the operator to replenish paper, and then the fuser (19)
) so that it falls into the mixing system 1.

i.e. the next step is to write a non-volatile note 1/15)
FUSERCV and FUsER-DUTY
is read out and compared in size to determine whether or not to enter the cleaning sequence of the heating fixing roll of the fixing device (19). As already mentioned, FUSERDUTY is the fuser unit (19
) A fixed number of 40,000 copies is written in advance as the number of copies that need cleaning. Since this is stored, if this cumulative number of copies does not reach the preset number, it is assumed that no offset has occurred to the heating and fixing roll 2, and the process proceeds to the normal copy cycle. If the number of sheets is greater than or equal to the above-mentioned certain number, the process proceeds to a cleaning cycle in which the surface of the heat fixing roll is cleaned. When proceeding to the normal copy cycle described above, set the control temperature of the heating and fixing roll to the control temperature of the above-mentioned C0NT TEMP normal copy cycle, that is, 189°C in this example, and proceed to normal copying. Execute the cycle.

On the other hand, when proceeding to the above-mentioned cleaning cycle, as described below, the control temperature of the heating and fixing roll is set to a lower temperature than that during a normal copy cycle, and a blank sheet is printed. This is based on the following findings:

That is, in developing a heat-resistant elastic body for a heat-fixing roll of a fixing device that does not use a release material as shown in FIG. However, it has been found that when the surface of the elastic body is wiped with a solvent such as alcohol, the releasability against toner is restored and the offset phenomenon no longer occurs. Furthermore, in an experiment to determine whether an offset phenomenon occurs when the surface temperature of the heat-fixing roll becomes fine, even if the heating window layer roll that has been contaminated with toner is returned to its original set temperature, the temperature will not change after that. However, the offset phenomenon occurs, but if you raise the surface temperature of the heat-fixing roll to a temperature higher than the temperature at which the offset phenomenon occurs and run a blank sheet of paper on which no toner image is placed, the toner stains on the surface of the heat-fixing roll will be removed from the white paper. It is transcribed into
It was discovered that the roll surface became clean and the roll could be used even at the set temperature when re-strung. In other words, this is equivalent to running a blank sheet of paper under high temperature or wiping the surface of the heat-fixing roll with two solvents.

Now, when the above-mentioned cumulative number of copies reaches 40,000 sheets, first, the control temperature of the heat fixing roll is adjusted by
The temperature is controlled to be set to TEMP. In this example, the control temperature during the cleaning cycle is set to 220°C, and please wait until the temperature reaches this "1 hour 7 degree" from 189°C. Turn on the ``Paper Replenishment'' light, instead of the ``Please Wait'' light, to ensure that there is a blank sheet of paper to flush when performing the cleaning cycle, if the paper has not yet been completely washed. If there is paper in the tray and the surface temperature of the heat fusing roll reaches 220°C, the "Please wait" lamp will be turned on and off and the operator will be asked to start the heat fusing process. Notifies that the cleaning cycle for cleaning the roll surface has started.

In the next step, before feeding the blank paper for cleaning, in order to maximize the cleaning area of the fixing device 09), select the paper tray in which the longest paper is set in the axial direction of the heating fixing roll. Then, a copying cycle starts in which the charger (20) and the developer tV are turned off. In this cycle, the paper fed out from the selected paper tray is conveyed along the same paper path as in normal stacking, passes through the fixing device (j9), and is ejected to the outside of the machine. (2t
1) and the developing device (2υ) are turned off, so the toner image reaches the fixing device (19) without any toner image on it, and the heated fixing roller and pressure roller of the fixing device 09) press and convey it. Therefore, as described above, at that time, toner stains on the surface of the heat fixing roller are transferred to the blank paper, thereby cleaning the surface of the roller. In this way, cleaning can be performed using the paper conveyance operation of the copying machine. ” In this example, the cleaning of the roller surface with the blank paper in step 1 is 3.
It is repeated eight times by rolling a blank sheet of paper. If a paper jam occurs during the copying process, the copying cycle will be interrupted and the number of copies will be corrected.If the copying cycle runs out, the copying cycle will be interrupted in the same way and the copying cycle will continue as before. The user maintains the number of blank sheets of paper that has been used and prompts for paper replenishment to ensure the number of times mentioned above three times.

After the fixed number of blank sheets (3 sheets) set in the above-mentioned FEED CNT has been passed, turn on the charger (4) mentioned above.
) and end the copying cycle with the current device ■υ turned off. When the cleaning of the fuser (19) is completed in this way, the cumulative number of copies of FUSERCV in non-volatile memory 05) is cleared to "0", and the control temperature of the heating fuser roll is set to normal. The ``Please wait'' lamp remains lit until the temperature returns to the control temperature during the copy cycle.
Furthermore, the paper tray selection is returned to the initial setting of the main tray as described above, and the normal copy cycle can then be executed. And the cumulative number of copies is 4
Do not repeat the cleaning cycle as described above every time you print 10,000 sheets.

In this way, the surface of the heat fixing roll can be easily cleaned only by electrical processing without using any cleaning device such as an elastic roll or web for the heat fixing roll or pressure roll. Since mold release agents such as silicone oil are not applied, there are no accidents caused by their use, which reduces troubles in the fuser unit, reduces inconvenience to users, and provides long-term use. It was possible to obtain good copies with no offset, and by repeating the cleaning cycle every certain number of copies, it was possible to achieve a roll life of over 200,000 copies.

In addition, in the above embodiment, the fixing device control part 1 during the cleaning cycle is
We have described the case where 220°C is selected as the temperature,
This is not limited to this temperature, but the surface temperature of the heat fixing roll when conveying white paper between the heat fixing roll and the pressure roll under pressure is set to a value between about 200°C and 240°C. It's good. Also, when writing a blank paper,
Instead of automatically selecting the tray containing the largest paper size at that time, it is also possible to request the operator to load the largest paper size that the copier can handle; The serviceman FUs the FUSER and CV values of non-volatile memo IJ 151.
By rewriting the value to be larger than the SERDUTY value, it is also possible to constantly execute the cleaning cycle as described above, if necessary.

Furthermore, in the above embodiment, the cleaning cycle is performed every certain number of copies, or instead of the number of copies, the number of processing start operations, or in the case of a copying machine, the print start button is set. It may be set every number of times the button is pressed.

〔Effect of the invention〕

As described above, the present invention makes it possible to easily clean the roll surface by effectively utilizing the recording support conveying operation in equipment using an electrophotographic process such as a copying machine, without using a special cleaning device in the fixing unit. It has features such as being able to obtain stable quality image recording over a long period of time without offset and without so-called oil stains caused by the release material used to prevent set.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a fixing unit in a fixing device that uses rolls but does not have a release material supply device, FIG. 2 is a block diagram showing the configuration of an embodiment of the present invention, and FIG. 8 is a diagram for explaining the present invention. FIG. 3 is a flowchart of a fuser cleaning cycle provided. (1)・・・Heat fixing roll (6)・・・・・・
・Pressure roll (8)...Paper (12)...
...Central processing unit 05) ...Non-volatile memory patent applicant Fuji Xerox Co., Ltd. Patent attorney Toshitomo Tsuchinaka J+! Same as Katsuo Naruse

Claims (1)

[Claims] A device for thermally fixing a toner image on a recording support by transporting the recording support under pressure using a roll, and controlling the apparatus so that one or more blank sheets are transported under pressure for each number of windows processed or for each predetermined number of processing start operations. A fixing device characterized by comprising means.