JPS5984274A - Picture fixing device - Google Patents

Abstract

PURPOSE:To eliminate wastefull feeding of a web and to extend a replacement period by driving a means for feeding the web independently of other driving systems and performing the driving only for a necessary period in the operation period of a picture forming device. CONSTITUTION:A signal S is sent to a control circuit 8 according to the advance of a picture forming process only during a light image exposure process in the entire operation period of the picture forming device. Consequently, the rotating force of a motor 6 is transmitted to a web take-up shaft 33 through a reduction gear train 7 to feed the web in a take-up direction. Further, the motor side 6 and web take-up shaft side 33 are coupled together through a clutch and the motor 6 is rotated all the time to transmit its rotating force to the web take-up shaft 33 intermittently by controlling the clutch through an on/off control circuit. Thus, wasteful feeding of the web is eliminated to extend the replacement period.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to the use of unfixed toner formed on the surface of an image supporting material such as transfer paper, electrofax paper, electrostatic recording paper, etc. in an image forming apparatus such as an electrophotographic copying machine or an electrostatic recording device. It relates to an image fixing device that fixes an image as a fixed image, and more specifically, it introduces an unfixed toner image-bearing material between a pair of heat rollers or a pair of pressure rollers and fixes the unfixed toner image on the surface of the carrier material by heat or heat pressure. , or relates to a fixing device of a pressure fixing type.

Fig. 1 shows a schematic configuration of an example of a heat roller type fixing device, and 1 and 2 are an upper heat roller and a lower opposing roller, which are held in parallel with each other and in contact with a moderate pressing force. Each of them is rotationally driven in the direction of the arrow by a drive system not shown in the figure. The heat roller 1 is heated by a heat source 11 disposed inside the heat roller 1, and the roller temperature is controlled to a predetermined appropriate heat fixing temperature by an automatic temperature control circuit (not shown).

The opposing roller 2 is, for example, a heat-resistant rubber roller. In some cases, this opposing roller 2 is also a heated roller.

3 is a web contact type heated roller cleaning mechanism;
32 is a web feeding shaft, 32 is a web pressure contact roller, 33 is a web winding shaft, and 34 is a cleaning web made of nonwoven fabric, etc. The web 34 is wound into a roll and is attached to the web feeding shaft 31, and the unwinding end is pressed against the web. roller 32
and the heat roller 1, and is hooked onto the winding shaft 33. Reference numeral 4 designates a fixing device housing, 41 designates an image bearing insertion hole into the fixing device, and 42 designates an exit thereof.

Then, from the image forming mechanism A side, the unfixed toner image-bearing material P is fed into the fixing device from the entrance 41 with the image surface facing upward by the relay conveying device 5, and is placed between the pair of rollers 1 and 2 rotating in the direction of the arrow. Enter and exit through exit 42. The unfixed toner image-bearing material P is heated by the heat roller 1 by passing between the rollers Ht 2 and is unfixed). Both toner images are heat-fixed or heat-pressure fixed on the surface of the carrier material 2 as a fixed image. .

The web contact type cleaning mechanism 3
4 is used to remove toner as dirt that is offset and adhered to one surface of the heat roller during image fixing. The web 34 is wound up slightly continuously or stepwise by the winding shaft 33, and the contact surface with the heat roller 1 is renewed.

In the case of a pressure fixing device, the pair of heat rollers 1 and 2 is a pair of pressure rollers made of steel or the like and brought into contact with each other under high pressure.

Hereinafter, the above heat roller pair or pressure roller pair will be collectively referred to as a fixing roller.

By the way, the web feeding (winding) drive of the cleaning mechanism 3 for the fixing roller has heretofore been synchronously linked to the rotation of the main motor of the image forming apparatus, or synchronously linked to the rotational drive of the pair of fixing rollers 1 and 2.

However, this configuration inevitably causes wasteful feeding of the web 34. That is, in general, when the image forming apparatus is turned on, the main motor starts driving, and after a predetermined warm-up period and a red standby period have elapsed, the image forming apparatus starts the actual image forming operation. The warming-up period is a period during which pre-rotation of the drum is performed in order to keep the surface potential of the photosensitive drum constant, as well as other preparatory operations for necessary process execution equipment. Further, even after copying or recording a predetermined single sheet or a series of consecutive multiple sheets, the drive of the drum and other necessary process execution equipment continues after a predetermined period of time, and then there is a standby period. The device is in a standby state until an image formation start signal is input. Therefore, the main motor synchronously interlocked cleaning mechanism is driven during the warm-up period and the drum post-rotation period other than the actual image forming operation period, and the web 34 is unnecessarily fed during this period.

Also, in the fixing device, in order to maintain a uniform set temperature distribution in each part of the roller pairs 1 and 2, the heater 11 is energized during the warming-up period, and the roller pairs 1 and 2 are rotated. It will be done. Therefore, the cleaning mechanism synchronously interlocked with the fixing roller is also driven in conjunction with the drive of the fixing device even during the warm-up period of the fixing device, which is outside the actual image forming operation period, and the web 34 is wasted during this period.

Such wasteful feeding of the web shortens the interval between web replacements, thereby shortening the service life.

There is also a system in which the web 34 is controlled to the required amount according to the magnification ratio or copy size during the image forming process. However, this type of control requires cumbersome circuits and programs, and is extremely difficult to control when there are many variable magnification ratios and copy sizes. Not only that, but in cases such as manual feed mode or copy paper priority mode, the optical system may scan differently even at the same magnification, and the actual amount of dirt on the fixing roller and web feed amount may not match. Ta.

An object of the present invention is to eliminate wasteful feeding of the web and extend the time for replacing the web in a heat or pressure roller type fixing device equipped with a web cleaning mechanism as described above.
The purpose is to perform simple and inexpensive web feeding control without requiring complicated control.

That is, in the present invention, the means for feeding the web 34 is driven independently without being interlocked with other drive systems such as the pair of fixing rollers 1 and 2 or the main motor of the image forming apparatus, and the drive is controlled during the operation period of the image forming apparatus. The gist of the present invention is an image fixing device that is characterized in that the image fixing is performed only for a predetermined period of time.

FIG. 2 shows an example of a mechanism in which the means for feeding the web 34, that is, the web winding shaft 33, is driven independently without interlocking with the pair of fixing rollers 1, 2, etc. 6 is a motor;
The rotational force of the motor is transmitted to the web winding shaft 34 via the reduction gear train 7 to feed the web in the winding direction.

8 is the on/off control circuit for the mokro. The motor side and the web winding 1hl133 side are connected via a clutch, the motor 6 is kept dry, and the clutch is controlled by an on-off control circuit to intermittently transmit the rotational force of the dry motor to the web winding shaft 33. You may also do so.

Only during a predetermined period of the entire operating period of the image forming apparatus, in correspondence with the progress of the image forming process, a signal S is sent to the control circuit 8 to turn on the motor 6 or the clutch and feed the web 34. Make it. Specifically, for example, (1) In the case of image formation by scanning the document surface with a movable optical system or a movable document table and applying light image exposure to the photosensitive drum surface, the light on the drum surface is The signal S is sent to the control circuit 8 to maintain the feed reweb 34 in the feeding state only during the forward or backward movement of the optical system or document table, which is the image exposure process. The signal S can be easily extracted mechanically or electrically from the optical system or the document table movement control mechanism or circuit. There may be some deviation in the correspondence between the above movement period of the optical system or document table and the period during which the unfixed image bearing material created in the image forming cycle is introduced and passes between the rollers 2 of the fixing device. (The latter is delayed), but it can be seen as a general agreement. Therefore, in response to the movement period of the optical system or document table mentioned above, by feeding the web only during that period, the unfixed image 1. The surface of the roller 1 can be kept clean by wiping off the toner with the successively updated surface of the web 34.

(2) As shown in the first diagram, a carrier material leading end arrival detection element S1 (for example, a CdS element and a light source) is installed on the unfixed toner image carrier entrance 41 side of the fixing device, and a carrier material rear end passage detection element is installed on the exit 42 side. 32 (same), and the amount control circuit 8 turns on the motor 6 or the clutch from when the leading end of the carrier material P introduced into the fixing device is detected by the element S1 until the rear end is detected by the element S1. maintain it. With this configuration, the web 34 can be controlled to be in the feeding state in accordance with the period in which the unfixed toner image bearing material P is passing between the fixing rollers 2.

(3) In addition, for example, unfixed toner is detected in relation to the start of rotation of the paper feed timing roller of the paper feed mechanism that feeds the transfer paper, which is an image-bearing material, to the transfer section of the photosensitive drum and the selected transfer paper size signal. It is also possible to control the web 34 to be fed only while the image bearing material is passing between the fixing rollers 2.

Here, if the process speed of the image forming apparatus is relatively high, or if the process speed can be switched between standard (hereinafter referred to as low speed for convenience) and high speed, high speed (for example, 300 mm/ 5ec), when the number of images processed per unit time is low (e.g. 210 mm/5ee).
Since the number of stains on the fixing roller 1 is greater than that, the degree of contamination of the fixing roller 1 also increases accordingly.

Therefore, at high speeds, the web 34 is continuously fed throughout the entire cycle from the feeding timing of the first sheet for continuous copying or recording to the completion of the optical system scan of the final sheet H. If the sequence is such that it continues, and if the time it takes for one sheet of paper to pass through the fixing device at low speed is, for example, 1 second, then web feeding will be performed for 0.7 seconds and stopped for 0.3 seconds. It is preferable to drive the motor 6 intermittently in such a sequence.

That is, by doing this, roller 1 can be processed at high speed.
Continuous renewal of the web 34 on the roller surface maintains good wiping of the roller surface even as the degree of contamination increases. During low-speed processing, sufficient wiping can be achieved even with intermittent web feeding as described above. At both high and low speeds, the web consumption associated with fixing per sheet of paper is approximately
The number of sheets processed per roll is approximately -1. The configuration and control can be simplified by keeping the driving speed of the motor 6 constant, and by switching the driving time between high-speed image processing and low-speed image processing to feed the web as described above.

The feed speed (winding speed) of the web 34 may be changed by switching the rotation speed of the motor 6 between high-speed image processing and low-speed image processing. However, in this case, the configuration and control tend to be more complicated than in the case of the constant motor drive speed method.

Second, in the present invention, the fixing roller or the means for feeding the leaning web is driven independently without being interlocked with the fixing roller or other drive system of the image forming apparatus, and its driving is controlled during the operation period of the image forming apparatus. Since this is carried out only for the required period, it is possible to eliminate unnecessary feeding of the web and extend the time for replacing the web.

FIG. 3 shows an example of a double-sided copying machine as an example of an image forming apparatus, where 100 is a main body of the copying machine, 200 is a bed disk on which the main body is placed, and 300 is a sorter (sorting device).

The originals are stacked and set on the placing table 1011 of the automatic document feeder 101 with the image surface facing downward, and are fed out to a predetermined position on the original platen glass 102 fixed to one sheet.
3, the light image is slit-exposed onto the surface of the photosensitive drum 104, and in combination with the action of electrophotographic process equipment disposed around the drum, a 1.sup.-image is formed on the circumferential surface of the drum. The toner image is transferred from the first or second cassette 1-106/107 of the paper feeding mechanism or from the 2000-sheet deck 108 provided on the pedicle 200 in synchronization with the rotation of the transfer unit 105. transcribed into. The transfer paper P that has undergone the image transfer is transferred to the drum 10.
The toner images are sequentially separated from 4 and introduced into a fixing device 109 as shown in FIG. In the case of single-sided copying, the transfer paper leaving the fixing device 109 is guided directly to the exit 110 of the main body of the copying machine, enters the sorter 300, and is conveyed to a predetermined stage I/ray of the sorting tray 301. Or if classification is not required, batch discharge tray 30
2. The scanned original is ejected from the original platen glass 102 to the paper output tray 111, and then the next original is fed onto the original platen glass 102, the original is subjected to copy processing, and then introduced into the sorter 300. . By repeating this process, single or multiple copies of all documents can be automatically made.

In the case of double-sided copying, the copy paper that has been subjected to single-sided copying after leaving the fixing device 109 is once sent to the paper re-feeding tray 112 of the reversing paper-feeding mechanism in the pedicle 200 by switching the path. Then, the transfer paper of the re-fed l/ray 112 is again fed to the transfer unit 105 in the copying machine main unit 100, where the image is transferred to the back side, separated from the drum 1 side, and introduced into the fixing device 109 again. By doing so, the toner image on the back side is fixed. As a result, a transfer paper that has been subjected to double-sided copy processing is obtained. The transfer paper enters the sorter 300 from the exit 110 of the copy board machine by changing the path,
It is transported to each classification tray 301 or batch discharge tray 302.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing a schematic configuration of an example of a hot roller type fixing device, FIG. 2 is a perspective view of a web winding mechanism, and FIG. 3 is a cross-sectional view showing a very schematic configuration of an example of a double-sided copying machine. figure. 1 and 2 are a pair of heat rollers, 34 is a cleaning web, and 6 is a web winding shaft drive motor.

Claims (1)

[Claims] (1) A pair of fixing rollers that allows the unfixed toner image to pass through the carrier material and fixes the toner image on the carrier material surface by heat or pressure, and a cleaning web that contacts the fixing roller to remove off-cellar l-toner from the fixing roller surface. and a means for feeding the web, the means for feeding the web is driven independently without interlocking with the fixing roller pair or other drive system of the image forming apparatus, An image fixing device characterized in that the image fixing device is driven only for a required period during an operation period of the image forming device.