JPH0453656Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a meandering prevention mechanism for continuous recording paper in a fixing device that fixes images transferred onto continuous recording paper.

(Prior Art) Conventionally, a photoconductor on the surface of a photoconductor drum is exposed to light to form a latent image, toner is attached to this latent image and developed, and the toner is transferred to recording paper and fixed by a fixing device. Image forming apparatuses using so-called electrophotography are mainly used in copying machines, but recently they have also been used in printers that print out computer output.

Copying machines generally use cut paper as recording paper, but printers are desired to use continuous recording paper, which is the same as that used in conventional line printers.

The continuous recording paper that is the same as the conventional paper is a folded continuous paper with sprocket holes (hereinafter simply referred to as continuous paper) called so-called fan-fold paper, and the folded part becomes a perforation so that it can be easily cut. It is something that exists.

Fixing methods include so-called heat roll fixing, in which the unfixed recording paper is sandwiched between a pair of rotating heatable fixing rolls and fixed by applying heat and pressure, and toner is applied to the recording paper by applying pressure with a pair of fixing rolls. A pressure fixing method (pressure roll fixing) is used in which the image is crushed and fixed. In either fixing method, the recording paper is conveyed and driven by the rotation of the fixing roll.

However, when pressure fixing and heat-pressure fixing are applied to continuous paper, the fixing roll pair is damaged due to factors such as poor initial biting into the fixing roll pair, uneven paper thickness, and elongation of the paper due to moisture absorption. The continuous paper held between the rollers becomes skewed or meandering, and the position where the continuous paper is caught by the pair of fixing rolls continuously changes in the lateral direction until it reaches the end of the opposite side of the fixing roll, causing wrinkles, resulting in poor fixing and poor conveyance. will occur.

To prevent this situation, we use a tensioning belt that has a protrusion that fits into the feed hole of the continuous recording paper.
A pulley on at least one of the front and rear sides of the two sets of left and right pulleys that are installed on both the left and right sides of the continuous recording paper introduction side of the fixing roll in parallel to the continuous recording paper conveyance direction, and connects the tension imparting belt. By connecting them with a shaft and making the shaft rotatable with a predetermined rotational resistance, a predetermined rotational resistance is applied to the rotation of the tensioning belt, and the projections of the tensioning belt fit into and engage with the feed holes of the continuous paper. It has been proposed that a tension-applying belt is rotated as the continuous paper is conveyed, and tension is applied to the continuous paper between the tension-applying belt and the fixing roll to prevent meandering.

(Problems with the prior art) However, in the conventional configuration described above, the rotations of the tension belts installed on the left and right sides are completely aligned, so they act to maintain the conveyance state of the continuous paper as it is. If the initial biting into the fixing roll can be done accurately, it can be expected to be effective in preventing skewing and meandering, but once the fixing roll is caught for some reason, such as poor initial biting or changes in the condition of the continuous paper during transport, Once it begins to skew or meander, it is difficult to restore it to a predetermined position. Therefore, there is a problem that if the conveyance is continued, fixing failure and conveyance failure will eventually occur.

(Purpose of the invention) In view of the above-mentioned circumstances, the present invention has been developed to prevent skewing and meandering, and also to prevent meandering of the fuser unit, which can easily and automatically return to the specified position even when skewing or meandering occurs. Its purpose is to provide a mechanism.

(Means for solving the problem) In order to achieve the above object, the meandering prevention mechanism of the fixing device according to the present invention is constructed by installing a pulley on a shaft having a predetermined rotational resistance via a tension control means,
When the continuous paper is skewed, the pulley on the skewed side spins idly in the opposite direction relative to the conveying direction, increasing the tension applied to the opposite skewed side of the continuous paper, allowing it to quickly return to the specified position. It is configured to do the following.

(Embodiment of the invention) Figures 1 and 2 show a laser beam printer device that uses fan-hold paper as the recording paper, and prints input from a computer, etc. on fan-hold paper 10 by electrophotography and outputs it. It is something.

Around the photosensitive drum 1, a toner cleaning section 2, a static eliminating section 3, a charging section 4, a scanning optical system 5 that guides a laser beam onto the photosensitive drum 1, a developing section 6, and a transfer section 7 are arranged along the drum rotation direction. The fan-hold paper 10 is arranged in a predetermined order, and the fixing unit 8 is
A meandering prevention 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 in the axial direction of the photosensitive drum 1 (main scanning) with a laser beam from the scanning optical system 5, and the formed latent image is transferred to the developing section. 6 to develop it into a toner image, and transfer the toner image to the fan hold paper 10 conveyed by the fixing section 8 at the transfer section 7.
At the same time, the image is transferred and fixed by the fixing section 8 and outputted.

The fixing unit 8 includes a pair of fixing rolls 81 and a back-up roll 82 that presses the pressure roll 81A on the lower side of the pair of fixing rolls 81 from below to above, which are installed in a direction perpendicular to the direction in which the fan-hold paper 10 is conveyed. has been done.

The fixing roll pair 81 includes a pair of upper and lower pressure rolls 8.
1A and 81B, and the distance between the outer peripheries of both pressure rolls 81A and 81B is such that when the fan-hold paper 10 is sandwiched between the two pressure rolls 81A and 81B, the fan-hold paper 10 is pressed with a predetermined pressure. The interval is set.

Further, the upper pressure roll 81B is connected to a drive motor 20 via a chain (not shown), and is rotationally driven by the drive motor 20 to fix the unfixed fan-hold paper 10 between the pair of fixing rolls 81.
The fan-hold paper 10 is pressed with a predetermined pressure to crush and fix the toner (so-called pressure fixing method), and at the same time, the fan-hold paper 10 is conveyed and discharged from the apparatus.

Note that the rotational circumferential speed of the photosensitive drum 1 and the pressure roll 8 are
The peripheral rotational speeds of No. 1 and No. 1 completely match, that is, the conveyance speed of the fan-hold paper 10.

The meandering prevention mechanism 9 is constructed by installing tension belts 91, 91 parallel to the conveyance direction under the feed holes at both left and right ends of the fan-hold paper 10 being conveyed from the transfer section 7 to the fixing section 8. has been done.

The tension belt 91 has a pulley 92 on the back side.
A, 93A is a so-called synchronized belt with projections and recesses (teeth) that mesh with each other, and its surface fits into feed holes 10A formed at 1/2 inch intervals on both sides of the fan hold paper 10. Protrusion 91A...
A plurality of holes are protruded in a line around the entire circumference at the same pitch (1/2 inch) as the sprocket hole 10A. Incidentally, the projections 91A are formed in a spindle shape so that the projections 91A can be easily inserted into the feed holes 10A.

Then, the fan hold is carried out by connecting the pulleys 92A..., 93A... installed on the two shear photos (rotating shaft 92 and fixed shaft 93) respectively installed in parallel in the direction orthogonal to the conveyance direction of the fan hold paper 10. It is installed parallel to the conveyance direction of the paper 10 and so that its upper surface coincides with the conveyance path of the fan-hold paper 10.

The rotating shaft 92 on the photosensitive drum 1 side is connected to the chassis 30 of the laser beam printer on one side.
The powder clutch 31 is connected to the powder clutch 31 fixed to the powder clutch 31, and is configured to be rotatable with a predetermined rotational resistance (torque).
A is installed.

The pulley 92A is installed on the rotating shaft 92 via a one-way clutch 92B, and is configured such that it cannot rotate relative to the rotating shaft 92 in the conveying direction of the fan hold paper 10, but can rotate relative to the rotating shaft 92 in the opposite direction. has been done.

It should be noted that a one-way clutch is one that acts on rotation in one predetermined direction (engages and becomes unable to idle), and allows idle rotation in the opposite direction.

That is, the rotary shaft 92 is rotatable with respect to the chassis 30 with a predetermined rotational resistance, and the pulley 92A cannot rotate relative to the rotary shaft 92 in the conveyance direction of the fan-hold paper 10, and cannot rotate in the opposite direction. It is installed so that it can be idled.

The fixing shaft 93 on the side of the fixing unit 8 is fixedly installed at both ends to the chassis 30 of the laser beam printer, and is connected to the feed hole 10A of the fan hold paper 10...
Pulleys 93A, 93A are installed at positions corresponding to the fixed shaft 93 so as to be rotatable relative to the fixed shaft 93.

Therefore, pulleys 92A, 92A and pulley 93
Tension belt 91, 9 connecting A, 93A
No. 1 is configured such that the fan-hold paper 10 can be rotated in the transport direction with a predetermined rotation resistance, and can be rotated in the opposite direction without resistance.

In the laser beam printer configured as described above, the fan hold paper 10 is inserted into the inlet 11.
The tension belt 9 of the meandering prevention mechanism 9 is introduced from
The protrusions 91A of No. 1, 91 are inserted into the feed holes 10A and set.

During printing, the meandering prevention mechanism 9 operates as follows.

In the fan-hold paper 10 between the photosensitive drum 1 and the fixing unit 8, protrusions 91A on the surface of the tension belts 91, 91 of the meandering prevention mechanism 9 penetrate and engage with the feed holes 10A on both left and right ends. The tension belts 91, 91 are rotated by being pulled by the fan-hold paper 10 conveyed by the fixing unit 8.

As described above, the tension belts 91, 91 rotate with a predetermined rotational resistance in the direction of conveying the fan-hold paper 10, and this resistance causes the fan-hold paper to move between the meandering prevention mechanism 9 and the fixing unit 8. 10, tension is applied equally to the left and right sides. This tension uniformizes the state of the fan-hold paper 10 introduced into the fixing roll pair 81 and acts to prevent skewing and meandering, but skewing or meandering may occur due to some factors. When this occurs, the tension applied to the side edges of the fan-hold paper 10 will be different on the left and right sides.

For example, fan hold paper 1 in the X direction in Figure 2.
0 is skewed, the fan hold paper 1 between the fixing roll pair 81 and the tension belts 91, 91
0, the protrusion 91 of the tension belt 91, 91
A... and the sprocket hole 10A of the fan hold paper 10...
... is engaged in the Y direction (L2-R1 direction)
Tension is generated.

Considering only this state, fan hold paper 1
0 is L side (L2-L1) and R side (R2-R1)
However, since it is conveyed and driven by the pair of fixing rolls 81, the tension belt 91 is driven on the L side, and tension is generated on the L side. That is, tension is applied to the triangular area formed by L1, L2, and R1.

However, the R side is still loose, and the rotational drive of the tension belt 91, that is, the shaft 92
does not contribute to rotational drive. Therefore, no tension is generated, and the pulley 92A on the R side rotates idly in the direction opposite to the transport direction relative to the shaft 9.

As a result, the tension applied to the side edge L side becomes larger than during normal transport (during normal transport) (during normal transport, tension is applied equally on both sides by driving on both sides, but when one side is driven (The tension applied to the driving side would be twice as much if it did not contribute to this), and tension is generated in the Y' direction (that is, the R2-L1 direction) opposite to the Y direction. Therefore, a force opposite to the skew direction X is generated and acts to correct (restore) the skew.

In the above embodiment, the pulleys 9 on both the left and right sides
Although both 2A and 92A are configured to be installed via the one-way clutch 92B, the fixing conditions of the fixing unit 8 (pressure force, distance between pressure rolls 81A, 81B, etc.)
Then, the installation conditions (such as the inclination of the conveyance roller with respect to the bag direction) are intentionally changed so that the fan-hold paper 10 is conveyed in a slightly oblique direction based on one side of the fan-hold paper 10, and only the pulley 92A on the side that tends to be oblique is set to one-way. If it is installed via the clutch 92B and configured to convey while regulating skew, it will not only be possible to quickly return to the predetermined position according to the skew tendency when skew or meandering occurs. It also reduces the number of parts used and reduces costs.

FIG. 3 shows the tension adjustment mechanism (that is, the part using the one-way clutch 92B) in the above embodiment.
This shows another example.

A pulley 92A is fitted to the shaft 92 so as to be relatively rotatable, a support 92D is fixed to one side of the pulley 92A, and a stopper 92F is fixed at a predetermined distance from the support 92D. Fix and both pillars 92D, 92
C is connected by a spring 92E.

Stopper 92F and shaft 92 support post 92C
is pulled into contact with the spring 92E. At this time, the distance between the support column 92D and the stopper 92F and the tensile strength of the spring 92E are set so that the tensile force of the spring 92E is a predetermined strength that is equal to or more than the strength that balances the rotational resistance of the shaft 92. be. In other words, tension is applied to the fan-hold paper 10 being conveyed via the spring 92E.

With this configuration, when skew occurs, the spring 92E stretches on the side end side where tension is generated (the L side in the above embodiment) to apply stronger tension. This makes it possible to quickly restore the device to its predetermined position.

(Effect of the invention) According to the meandering prevention mechanism of the fixing device according to the invention,
By configuring a pulley that applies rotational resistance to the tensioning belt so that it can idle in the direction opposite to the conveyance direction of the continuous paper via a tension control means, the tension at the left and right ends of the continuous paper when skew occurs is reduced. Due to this difference, the pulley on the side of the continuous paper in the diagonal direction rotates idly in the opposite direction relative to the conveyance direction, allowing greater tension to be applied to the end on the opposite side of the paper, making it possible to correct the skew in a powerful and reliable manner. This can be done.

That is, even if skew or meandering occurs, it can be automatically restored to a predetermined position.

[Brief explanation of the drawing]

FIG. 1 is a side view of the configuration of a printer using a meandering prevention mechanism for a fixing device according to the present invention, FIG. 2 is a plan view thereof, and FIG. 3 is a perspective view of another embodiment. 8... Fixing unit (fixing device), 81... Fixing roll pair (fixing roll), 9... Meandering prevention mechanism 91 tension belt (tension belt), 91A... projection, 92... Idle shaft (predetermined Shaft that can be rotated with rotational resistance), 92A...Pulley, 92B
...One-way clutch (tension control means), 10
...Fanhold paper (continuous recording paper), 10A...
...feeding hole.

Claims (1)

[Scope of utility model registration request] A tensioning belt with protrusions that fit into the feed holes of continuous recording paper can be rotated parallel to the conveyance direction of the continuous recording paper on both the left and right sides of the continuous recording paper introduction side of the fixing roll for pressure fixing and heat-pressure fixing. At the same time, out of the two sets of left and right pulleys that connect the tensioning belt, at least one of the front and rear pulleys is connected by a shaft, and the shaft is configured to be rotatable with a predetermined rotational resistance. A meandering prevention mechanism for a fixing device that applies a predetermined rotational resistance to the rotation of a tensioning belt, characterized in that a pulley connected by the shaft is installed on the shaft via a tension control means. Mechanism to prevent meandering of the vessel.