JPH0659955B2 - Fixer meandering prevention mechanism - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a meandering prevention mechanism for continuous recording paper in a fixing device for fixing an image transferred on continuous recording paper.

(Prior Art) Conventionally, for example, a photoreceptor on the surface of a photosensitive drum is exposed to form a latent image, toner is attached to the latent image for development, and the toner is transferred to a recording sheet and fixed by a fixing device. An image forming apparatus using a so-called electrophotographic method is mainly used as a copying machine. A cut sheet (single sheet) is used as a recording sheet, and a fixing method is a heat roll fixing method for fixing toner by heat. It is common. Further, recently, pressure fixing, which consumes less power and does not require preheating time of a heat roll, has begun to be adopted.

However, the image forming apparatus utilizing the electrophotographic method has come to be used for a printer or the like which prints out the output of a computer recently, and the recording paper is the same continuous recording paper as that used in the conventional line printer. Has become desired.

The continuous recording paper that is the same as the conventional one is a folding continuous paper with a feed hole (hereinafter simply referred to as continuous paper) called a so-called fan-hold paper, and the folded portion is a perforation and is easily cut. There is something.

When such a continuous paper is used in the heat roll fixing method, since the recording paper (continuous paper) is in contact with the heat roll during printing standby, heat continuously applied causes various problems such as kogation. . In order to solve this problem, the heat roll must be separated from the recording paper during printing standby, and since the apparatus becomes large and complicated, the flash fixing method is used.

However, even in the flash fixing method, there are problems that the apparatus becomes large in size and power consumption increases, and electromagnetic noise causes adverse effects on other devices. It is considered.

In pressure fixing, an unfixed recording paper is sandwiched between a pair of rotating fixing rolls and pressed with a predetermined pressure to crush the toner onto the recording paper to fix it. Normally, the recording paper is rotated by rotating the fixing roll. Is also configured to be driven.

(Problems of the prior art) However, when pressure fixing is applied to continuous paper, it may be caused by factors such as initial biting into the fixing roll pair, defects, uneven thickness of the paper, and elongation of the paper due to moisture absorption. The continuous paper nipped by the pair of fixing rolls skews or meanders, and the biting position of the pair of fixing rolls continuously changes in the lateral direction to reach the side edge, causing wrinkles and defective fixing and conveyance failure. There is a fatal problem.

The skew or meandering of the recording sheet is not a problem in the cut sheet (because the length is limited). In addition, the same situation occurs in the heat roll fixing,
Particularly in pressure fixing, it is extremely difficult to prevent it because the pressure applied to the recording paper is higher than in heat roll fixing.

(Object of the Invention) In view of the above circumstances, the present invention provides a fixing device capable of preventing skew and meandering and automatically restoring to a predetermined position even when skew or meandering occurs. The purpose is to provide a meandering prevention mechanism.

(Means for Solving the Problems) In order to achieve the above object, the meandering prevention mechanism of the fixing device according to the present invention uses an unfixed toner on a continuous recording paper having a feed hole at a side end to fix a fixing roll and a pressure roll. In a fixing device of a type in which pressure fixing or heat pressure fixing is performed by passing between the fixing roller and the pressure roller, the transfer unit that transfers the toner onto the continuous recording paper, An endless belt having a plurality of protrusions fitted into and engaged with a feed hole of the continuous recording paper is provided, and the continuous recording paper is driven by rotating at least one of the fixing roll and the pressure roll. It is characterized in that it is driven by a predetermined circling resistance in the carrying direction of the paper.

(Embodiment of the Invention) FIG. 1 shows a laser beam printer using a fan-hold paper as a recording paper, which prints an input from a computer or the like on a fan-hold paper 10 by an electrophotographic method and outputs it.

Around the photosensitive drum 1, a toner cleaning unit 2, a charge eliminating unit 3, a charging unit 4, a scanning optical system 5 for guiding a laser beam onto the photosensitive drum 1, a developing unit 6, and a transfer unit 7 are arranged along the drum rotation direction. The fixing units 8 are arranged in a predetermined order, and the fixing unit 8 is arranged in front of the fan-hold paper 10 in the conveying direction, and the tension applying mechanism 9 is installed in the continuous paper path from the photosensitive drum 1 to the fixing unit 8. .

Then, the photosensitive drum 1 is rotated (sub-scanning) and the surface of the photosensitive drum 1 is scanned (main scanning) by the laser beam from the scanning optical system 5 in the axial direction of the photosensitive drum 1 to form a latent image on the developing unit. The toner image is developed by 6 and transferred to the fan-hold paper 10 by the transfer unit 7 and is fixed by the fixing unit 8 and output.

The fixing unit 8 is configured such that a fixing roll pair 81 and a backup roll 82 that presses the lower pressure roll 81A of the fixing roll pair 81 from below to above are installed in a direction orthogonal to the transport direction of the fan hold paper 10. ing.

The fixing roll pair 81 is a pair of upper and lower pressure rolls 81A.8.
1B, both pressure rolls 81A ・ 81
The interval between the outer circumferences of B is set to an interval at which the fan hold paper 10 is pressed with a predetermined pressure when the fan hold paper 10 is sandwiched between the pressure rolls 81A and 81B.

The upper pressure roll 81B is connected to the drive motor 20 via a chain (not shown), and is driven to rotate by the drive motor 20 to sandwich the unfixed fan hold paper 10 between the fixing roll pair 81 and to perform a predetermined operation. Press with the pressure of
The toner is crushed and fixed (so-called pressure fixing method), and the fan hold paper 10 is conveyed and driven to be discharged to the outside of the apparatus.

The rotational peripheral speed of the photosensitive drum 1 and the rotational peripheral speed of the pressure roll 81 are completely the same, that is, the fan hold paper 10
The transport speed is.

The tension applying mechanism 9 is configured by installing endless belts 91, 91 below the left and right ends of the fan hold paper 10 conveyed from the transfer unit 7 toward the fixing unit 8 in parallel with the conveyance direction. .

The endless belt 91 is a so-called synchro belt having concavities and convexities (teeth) that mesh with the pulleys 92A and 93A formed on the back surface, and feed holes formed on both sides of the continuous paper 10 at 1/2 inch intervals on the front surface thereof. Protrusion 91A fitting with 10A ...
However, a plurality of protrusion holes are provided in a line over the entire circumference at the same pitch (1/2 inch) as the feed holes 10A. That is, the length of the endless belt 91 is an integral multiple of the pitch (1/2 inch) of the feed holes 10A. Also, the protrusion 91A
Are formed in a spindle shape so that the protrusions 91A can be easily inserted into the feed holes 10A.

.., 93A, which are installed on the two shafts 92, 93 provided in parallel to the direction in which the fan hold paper 10 is conveyed, are parallel to the fan hold paper 10 in the conveyance direction. , Its top surface is continuous paper 1
It is installed so as to coincide with the transportation route of 0.

The distance between the shafts 92 and 93 is such that the endless belt 91, the length of which is regulated by the pitch of the feed holes 10A ... Is connected by a predetermined tension, and the ten projections 91A ...
It is set at a predetermined interval for fitting and engaging with A ...

The pulleys 92A and 93A are gears that mesh with the irregularities on the back surface of the endless belt 91. The pulleys 93A on the fixing portion 8 side are rotatably installed on the shaft 93, and the pulleys 92A on the photosensitive drum side are the shafts. It is configured to be rotatable with a predetermined rotation resistance with respect to 92. That is, the pulleys 92A ... Are configured to give a predetermined winding resistance to the winding of the endless belts 91.

As a method of imparting a predetermined rotation resistance to the pulleys 92A ..., the fitting portion between the pulleys 92A ... and the shaft 92 may be constituted by a bearing having a predetermined rotation resistance, and for example, a powder clutch or the like may be used.

This circulating resistance value is related to the number of engagements of the projections 91 of the endless belt 91 with the feed holes 10A of the fan hold paper 10 (the load applied to the feed holes 10A ... causes the feed holes 10A ...
Is not damaged), and the tension must be such that the fan hold paper 10 and the fixing roll pair 81 are absolutely not cut from the perforations, and 300 g to 400 g on one side,
It is appropriate to set 600g to 800g on both sides.

Thus, in the laser beam printer configured as described above, the fan hold paper 10 introduced from the introduction port 11 is
The leading end of the fixing unit 8 is provided between the photosensitive drum 1 and the transfer unit 7.
While being engaged between the fixing roll pair 81, the projections 91A of the endless belts 91 of the tension applying mechanism 9 are fitted into the feed holes 10A.

At the time of printing, the surface of the photosensitive drum 1 is scanned by the scanning optical system 5 with a laser beam from a semiconductor laser (not shown) to form a latent image on the surface of the photosensitive drum 1 and toner is attached to the latent image by the developing unit 6. Then, the toner is transferred to the fan hold paper 10 by the transfer unit 7. The fan hold paper 10 to which the toner has been transferred is conveyed and driven by the pressure roll 81B of the fixing unit 8 that rotates in synchronization with the photosensitive drum 1, and is conveyed toward the fixing unit 8.

Fan hold paper 1 between the photosensitive drum 1 and the fixing unit 8
0, the endless belts 91, 91 of the tension applying mechanism 9 penetrate through the feed holes 10A at the left and right ends and engage with the feed holes 10A, so that the fan hold paper 10 conveyed by the fixing unit 8 is pulled. Then, the endless belts 91 are driven to rotate.

The endless belts 91, 91 have a predetermined winding resistance as described above, so that tension is applied to the fan hold paper 10 between the tension applying mechanism 9 and the fixing unit 8.

In this way, the fan hold paper 1 introduced into the fixing unit 8
By applying a predetermined back tension (tension) to 0, the state of the fan hold paper 10 introduced into the fixing roll pair 81 is made uniform, the occurrence of skew and meandering is prevented, and the fan hold paper 10 is prevented. The position of the left and right direction of the is regulated by the projections 91A of the endless belts 91, ...
Even if skewing or meandering occurs due to some factor, it automatically restores to a predetermined position.

In the present embodiment, the ten feed projections 10A of the fan hold paper 10 are simultaneously engaged with ten projections 91A of the endless belt 91.
The number is not limited to one, but may be any number as long as it does not damage the feed holes 10A ... In view of the tension applied to the fan hold paper 10 and the strength of the feed holes 10A. .

Further, one side of the fan hold paper 10 is intentionally changed by intentionally changing the fixing conditions (pressing force, the distance between the pressure rolls 81A and 81B, etc.) and the installation conditions (inclination with respect to the conveying direction, etc.) on the left and right of the fixing roll pair 81 in the conveying direction. As a reference, if the setting is made such that the sheet is conveyed in a slightly skewed manner and the tension is provided by the tension applying mechanism 9 while the skew is regulated, the sheet can be swiftly moved to a predetermined position according to the skewed tendency when skewing or meandering occurs. It can also be configured to return to.

Further, the installation of the tension applying mechanism 9 is not limited to the one in which the fixing and the conveyance driving are simultaneously performed by the pair of fixing rolls.
It may be used in a roll driven only by a transport drive or a device driven by other means such as a tractor belt, and the fixing method is not limited to the pressure fixing method, and may be a heat fixing method (so-called heat roll fixing). Of course, it may be applied to things.

(Advantages of the Invention) According to the meandering prevention mechanism of the fixing device according to the present invention, the plurality of protrusions of the endless belt are configured to be engaged with the feed holes of the continuous paper to apply tension, so that the tension is reliably applied. It is possible to prevent the continuous paper from skewing and meandering.

In addition, the position of the continuous paper in the middle of conveyance is regulated to a fixed position, and therefore the position of the continuous paper introduced to the fixing roll is also regulated, so even if skewing and meandering occur, it will automatically reach the predetermined position. It is possible to prevent wrinkles, that is, improper fixing and improper conveyance from occurring.

[Brief description of drawings]

FIG. 1 is a configuration side view of a printer using a meandering prevention mechanism of a fixing device according to the present invention, and FIG. 2 is a perspective view of the meandering prevention mechanism of the fixing device. 8 ... Fixing unit (fixing device) 81 ... Fixing roll pair (fixing roll) 91 ... Endless belt, 91A ... Protrusions 10 ... Fan hold paper (continuous recording paper) 10A ... Feed hole

Claims (1)

[Claims] 1. A fixing device of a type in which unfixed toner on a continuous recording paper having a feed hole at a side end is pressure-fixed or heat-pressure-fixed by passing between a fixing roll and a pressure roll. An endless belt having a plurality of protrusions that are fitted into and engaged with the feed holes of the continuous recording paper is provided between the transfer unit that transfers the toner onto the continuous recording paper and the fixing roll and the pressure roll. The endless belt is driven by a predetermined circulating resistance in the carrying direction of the continuous recording paper when the continuous recording paper is carried by the rotational driving of at least one of the fixing roll and the pressure roll. Meandering prevention mechanism for vessels.