JP3236093B2 - Transfer belt device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel transfer belt device, and more particularly, to an image forming apparatus such as a PPC (plain paper copier), a printer, a facsimile, etc., using an electrostatic transfer system. The present invention relates to a transfer belt device that can perform the transfer.

[0002]

2. Description of the Related Art Hitherto, various methods have been proposed for obtaining a good transfer image on various transfer papers and various environments in an image forming apparatus provided with electrostatic transfer. Among them, in a transfer device using a dielectric belt as a transfer means, a charge is applied to the dielectric belt without directly giving a charge to the transfer paper. The transfer paper is attracted to the dielectric belt by the electrostatic attraction, and a force for transferring the toner image on the photoconductor is generated by the electric charge applied to the dielectric belt. Therefore, the separation of the transfer paper from the photoconductor, the transfer of the toner image to the transfer paper, and the transfer of the transfer paper to the fixing device are performed without being affected by differences in the type of transfer paper and environmental conditions. It can be performed stably without causing deterioration or paper jam.

In the transfer belt system, when the transfer paper is misfeet (so-called jam), it is necessary to enhance the removability of the misfeet paper. A transfer belt release mechanism is provided for separating the misfeet paper so that the paper can be removed. As such a known technique, a transfer belt device configured to separate only the transfer belt from the photoconductor (see Japanese Patent Application Laid-Open No. 53-120442), and a transfer belt device configured to separate the entire transfer belt device from the photoconductor (Japanese Unexamined Patent Application Publication No. H11-157421). JP-A-63-85666) is known.

[0004]

However, in the above-described belt transfer method, the transfer is performed in the vicinity of a contact portion (hereinafter, referred to as a nip portion) where the photosensitive member and the transfer belt are in contact with each other. Therefore, the positional accuracy of the nip becomes extremely important. In particular, in the case of an image forming apparatus having a transfer belt release mechanism, since the transfer belt takes two states, that is, a state in which the transfer belt is in contact with the photoconductor and a state in which the transfer belt is apart from the photosensitive body, the position accuracy of the nip portion is always stably maintained. There was a difficult problem.

More specifically, in the case of an image forming apparatus having a transfer belt releasing mechanism, the position of the nip portion changes due to mechanical vibration caused by a copying operation, pressure due to the thickness of the paper when the transfer paper enters the nip portion, and the like. It is necessary to hold the transfer belt with a sufficient holding force so that the transfer / transport unit itself deforms when a certain force or more is applied to the transfer / transport unit base holding the transfer belt, and as a result, the nip position May fluctuate.

When a transfer belt is used, the transfer belt is biased in order to always maintain a good transfer state.
It is important to prevent meandering. One of the causes of the deviation of the transfer belt and the meandering is that the transfer belt is twisted due to insufficient parallelism of the two rollers passing over the transfer belt. In particular, in the case of an image forming apparatus having a transfer belt release mechanism, the transfer belt is easily moved and the twist is easily generated while the transfer belt is separated from the photoconductor and during the separation operation. there were.

[0007] The present invention has been made in view of the problems described above, the transfer belt device having a release driving means for separating from the photoreceptor the transcription belt, shift of the transfer belt, meandering, twisting, etc. The purpose of the present invention is to provide a transfer belt device that can prevent the occurrence of
I do.

[0008]

[0009]

[0010]

To achieve the above object, according to an aspect of, the transfer belt device according to claim 1, which stretched the transfer belt, the transfer belt which is in contact with the outer peripheral surface of the image information carrier rack Tensioning means, transfer belt driving means for driving the transfer belt, positioning means for positioning the transfer belt with respect to the image information carrier, and applying a transfer bias to the transfer belt near the image information carrier. A bias applying means for applying, a transfer / conveying unit base supporting at least the transfer belt, the stretching means, and the bias applying means, and the transfer / conveying unit base being rotated about a predetermined rotation fulcrum as an axis. A transfer belt device having a release driving unit that causes the transfer belt to contact or separate from the image information carrier,
When the transfer belt is separated from the image information carrier, the transfer belt and the image information carrier are not rotated and stopped, and the transfer belt is in contact with the image information carrier and the positioning is performed. After the position is fixed by the means, the rotation of the transfer belt and the image information carrier is performed.

[0011]

According to the first aspect of the present invention, the transfer belt
When the roller is separated from the image information carrier,
There is no force on the photo belt, so it's leaning, meandering,
Are abnormalities such as kinking likely to occur?
The transfer belt is separated from the image information carrier.
Occasionally, the image information carrier is stationary without rotating
This causes the transfer belt to shift, meander, and twist.
It is possible to prevent the occurrence of abnormalities such as.

[0012]

[0013]

[0014]

[0015]

BRIEF DESCRIPTION real施例of the present invention. FIG. 1 is a schematic perspective view showing a part of a copying machine employing a transfer belt device to which the present invention can be applied . In FIG. 1, reference numeral 1 denotes a photosensitive drum, which is not shown around the photosensitive drum 1. Although not shown, a charger for applying a charge to the photosensitive drum 1 and an electrostatic latent image by irradiating predetermined image light are provided. , A developing unit that forms a visible image by attaching toner to an electrostatic latent image, and a cleaner unit that removes residual toner on the photosensitive drum 1 are provided at predetermined positions. . A transfer belt unit 2 is provided between the developing unit and the cleaner unit below the photosensitive drum 1 so as to be in contact with the photosensitive drum 1.

The transfer belt unit 2 is provided so as to face an elastic transfer belt 3, a drive roller 4 for driving the transfer belt 3, and the drive roller 4, and taper both ends to shift the transfer belt. A transfer roller 6 disposed downstream of the photosensitive drum 1 and inside the transfer belt for applying a transfer bias; and a predetermined position and a predetermined width on the photosensitive drum 1 and the transfer belt 3. Positioning member 7 provided to form nip portion 30
A cleaning blade 8 for cleaning the surface of the transfer belt 3; and a toner receiver 9 for receiving toner and paper dust scraped off by the cleaning blade 8.
And a transfer belt unit structure 1 that supports the above elements
And 1. The transfer belt 3 is operated at a predetermined position below the transfer belt unit structure 11 by a signal from a transfer control unit (not shown) to move the transfer belt 3 to the photosensitive drum 1.
A transfer belt unit push-up lever 10 is provided for contacting or separating the transfer belt unit.

FIG. 2 is a perspective view in which the positioning member 7 is extracted and drawn. The shaft 22 supporting the transfer belt 3 and the shaft 2 are shown in FIG.
2 and flange portions 23 provided at both ends,
The transfer belt 3 can be positioned with respect to the photosensitive drum 1 by the flange portion 23 being in contact with the photosensitive drum 1 or the frame of the photosensitive drum 1 .

The transfer belt unit structure 11 Figure 3 and drive roller 4 side of the end pivot point 1 as shown in FIG. 4
2 is rotatably supported by the transfer belt unit structure 11 to rotate according to the vertical movement of the transfer belt unit pushed up lever 10, it is brought into contact with the transfer belt 3 shown in Figure 3 to the photosensitive drum 1 It is configured to take a state and a separated state as shown in FIG.
3 and 4, reference numeral 21 denotes a transfer paper 20.
Is a supply roller for supplying the transfer belt 3 to the transfer belt 3.

The distance from Kaido支point 1 2 of the transfer belt unit structure 11 to the nip portion 30 of the photosensitive drum 1 and the transfer belt 3 in this example La, photoreceptor positioning member 7 from the pivot point 12 The distance Lb from the contact point with the drum 1 and the distance Lc from the pivot point 12 to the point of application of the force of the transfer belt unit lifting lever 10 are substantially equal. Therefore, when the transfer belt unit structure 11 is pushed up by the transfer belt unit push-up lever 10 as shown in FIGS. 3 and 4, the action by the pushing force f, the pressure by the nip 30 and the pressure by the positioning member 7 are reduced. The transfer belt unit structure 11 can be almost balanced, and deformation of the transfer belt unit structure 11 can be minimized. With this configuration,
The transfer belt 3 can be held by a sufficient holding force so that the position of the nip portion 30 does not change due to mechanical vibration or pressure due to the thickness of the paper when the transfer paper 20 enters the nip portion 30, Good transfer can always be achieved.

Next, the operation of the above-described transfer belt device will be briefly described. When the transfer paper 20 enters the nip portion 30 by the supply roller 21, a transfer bias is applied by the transfer charger 6, and a charge having a polarity opposite to that of the toner on the photosensitive drum 1 is applied to the transfer belt 3. Then, the toner on the photosensitive drum 1 is transferred onto the transfer paper 20.

At this time, the transfer belt 3 has a belt surface having an electric resistance of 1 × 10 ⁹ ohm to 1 × 10 ¹² ohm and an electric resistance inside the belt of 1 × 10 ⁷ ohm to 1 × 10 ⁸ ohm. Transfer belt 3 and transfer paper 2
As the charge applied on the zero moves to the downstream side, the charge is removed by a contact plate (not shown), and the charge amount is reduced. The transfer paper 20 having weakened electrostatic attraction force is separated from the transfer belt 3 at the position of the drive roller 4, and the toner is fixed on the transfer paper 20 by a fixing device (not shown).

When a series of transfer operations is completed, the transfer belt unit push-up lever 10 is released as shown in FIG. 4, and the transfer belt 3 is separated from the photosensitive drum 1. This is to prevent deterioration and contamination of the photosensitive drum 1 due to long-term contact between the transfer belt 3 and the photosensitive drum 1. The transfer belt 3 being transported has a transfer belt 3
Although there are also residual toner adhered thereon and paper dust from the transfer paper 20, these are scraped off by the cleaning blade 8 in contact with the drive roller 4 and collected in the toner receiver 9.

Next, another example of a transfer belt apparatus to which the present invention can be applied will be described with reference to FIGS. Nip portion of the photosensitive drum 1 and the transfer belt 3 from the pivot point 12 of the example of this is the transfer belt unit structure 11 30
The distance La from the rotation fulcrum 12 to the contact point of the positioning member 7 with the photosensitive drum 1 is shown in FIG.
In the case where the transfer device is configured such that La> Lb as shown in FIG.
b so that the transfer belt unit push-up lever 10
Is arranged.

When the transfer device is configured so that La <Lb as shown in FIG. 6, the transfer belt unit push-up lever 10 is positioned so that Lc <Lb. With the above-described configuration, when the positioning member 7 abuts on the photosensitive drum 1 or the frame of the photosensitive drum 1 and a force is applied to further increase the holding force after the positioning member 7 abuts on the nip portion 30, the nip 30 is brought into contact with the nip 30. The transfer belt unit structure 11 can be prevented from being deformed with the portion as a fulcrum.

FIG. 7 is a view showing a configuration in which the transfer belt unit push-up lever 10 is disposed so that Lc <Lb when La> Lb.
It can be understood that as the holding force f of the transfer belt unit lifting lever 10 is increased, the transfer belt unit structure 11 is distorted and the nip portion 30 becomes unstable.

FIG. 8 shows that when La <Lb, Lc>
Lb so that the transfer belt unit push-up lever 1 is set to Lb.
0 is a view showing a configuration in which the transfer belt unit structure 1 is arranged in such a manner that as the holding force f of the transfer belt unit push-up lever 10 is increased, the transfer belt unit structure 1 is increased.
It can be understood that 1 is distorted in the direction in which the nip portion 30 separates and becomes unstable.

Next will be described with reference to FIGS. 3 and 4 for the transfer belt device according to the real施例of the present invention. In this embodiment, as shown in FIG. 4, when the transfer belt 3 is separated from the photosensitive drum 1, the transfer belt 3 and the photosensitive drum 1 do not rotate, but are stopped. Then, as shown in FIG. 3, after the transfer belt 3 is in contact with the photosensitive drum 1 and the position is fixed by the positioning member 7, the transfer belt 3 and the photosensitive drum 1 are rotated. The feature is that. One method of constructing this embodiment is to respond to a drive signal of the transfer belt unit push-up lever 10,
There is a method in which the rotation of the driving roller 4 is stopped. According to this embodiment, it is possible to prevent occurrence of abnormalities such as deviation, meandering, and twisting of the transfer belt 3 with a simple configuration.

[0028]

As described above, the invention of claim 1 is simple.
In a transfer belt device with a simple configuration,
Can prevent abnormalities such as meandering, twisting, etc.
There is an effect.

[0029]

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing an example of a transfer belt device to which the present invention can be applied .

2 is a perspective view of a positioning member of the transfer belt unit of Figure 1.

3 is a diagram for explaining the operation of the transfer belt unit of Figure 1.

It is a diagram for explaining the operation of the transfer belt device of FIG. 1;

FIG. 5 is a diagram illustrating another example of a transfer belt device to which the present invention can be applied .

FIG. 6 shows still another transfer belt device to which the present invention can be applied .
It is a figure showing the example of.

FIG. 7 is a diagram illustrating a configuration of a transfer belt device in which a nip portion becomes unstable.

FIG. 8 is a diagram illustrating a configuration of a transfer belt device in which a nip portion becomes unstable.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 photosensitive drum 3 transfer belt 4 drive roller 5 subordinate roller 6 transfer charger 7 positioning member 10 transfer belt unit push-up lever 11 transfer belt unit structure 12 rotation fulcrum

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-4-133087 (JP, A) JP-A-3-230185 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 15/16

Claims (1)

(57) [Claims] A transfer belt that is in contact with an outer peripheral surface of the image information carrier; a stretching unit that stretches the transfer belt; a transfer belt driving unit that drives the transfer belt; Positioning means for positioning the transfer belt with respect to the transfer belt, bias applying means for applying a transfer bias to the transfer belt in the vicinity of the image information carrier, at least the transfer belt, the stretching means, and the bias application. A transfer unit that supports the transfer unit, and a release driving unit that rotates the transfer unit base around a predetermined rotation fulcrum to contact or separate the transfer belt from the image information carrier. In the belt device, the transfer belt is
When the transfer bell is separated from the image information carrier,
And the image information carrier is stationary without rotating.
And transferring the transfer belt to the image information carrier.
Abuts and the position is fixed by the positioning means.
The transfer belt and the image information
A transfer belt device configured to rotate the carrier .