JP3262477B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus for forming an image on a recording material carried on a recording material carrier, for example, an image forming apparatus such as a copying machine or a laser beam printer using an electrophotographic system. About.

[0002]

2. Description of the Related Art An image forming apparatus that forms a color image by sequentially transferring a plurality of color toner images sequentially formed on a photoreceptor onto a transfer paper wound around a transfer drum is used.

When the transfer paper is wound around the transfer drum while holding the leading end of the transfer paper by a gripper provided on the transfer drum, only one transfer paper can be wound around the transfer drum.

Therefore, when the length of the transfer paper in the paper passing direction is less than the letter size (about 216 mm), the transfer paper is transferred to the transfer drum by electrostatically attracting the transfer paper to the transfer drum using a suction roller. Two pieces are wound simultaneously on the top.

[0005]

However, in the above-mentioned prior art, when the transfer paper is attracted onto the transfer drum, if the transfer paper is wavy as shown in FIG. Until the contact portion between the suction roller and the transfer drum just before the contacted portion, the portion first contacts the transfer drum and is sucked.

Then, even after a part of the area of the transfer paper that is concave with respect to the transfer drum has passed through the contact position between the suction roller and the transfer drum, the transfer paper floats from the transfer drum. There was something.

When the area where the transfer paper floats with respect to the transfer drum as described above, there is a disadvantage that the toner is not efficiently transferred in this area and the transfer is lost.

FIG. 4 is a cross-sectional view showing a state in which the transfer paper is adsorbed on the transfer drum while being wavy. This phenomenon of waving of the transfer sheet is particularly noticeable in a high-temperature and high-humidity environment, and when the image is transferred to the second side of the transfer sheet having the image fixed on the first side.

Therefore, an object of the invention according to the present application is to make the recording material uniformly supported on the recording material carrier by stretching the undulations of the recording material before supporting the recording material on the recording material carrier. That is, a good image is formed on the recording material.

[0010]

According to the present invention, there is provided a recording material carrier for supporting a recording material, an adsorbing means for electrostatically adhering the recording material to the recording material carrier, In an image forming apparatus, comprising: a supply unit that supplies a recording material to the suction unit; and an image forming unit that forms an image on the recording material carried by the recording material carrier, the supply unit in a moving direction of the recording material. Between the and the suction means, shorter than the length of the recording material in a direction perpendicular to the direction of movement of the recording material,
And an ironing member for pressing a central portion of the recording material in a direction orthogonal to the moving direction of the recording material toward the recording material carrier.

[0011]

【Example】

(First Embodiment) FIG. 11 is a schematic diagram of an electrophotographic full-color image forming apparatus according to a first embodiment of the present invention.

In FIG. 1, reference numeral 100 denotes an image forming apparatus main body.

In FIG. 1, reference numeral 101 denotes a photosensitive drum as an image carrier, which has a predetermined peripheral speed (process speed) in a clockwise direction.
, And is rotationally driven by driving means (not shown). Reference numeral 1 denotes a transfer drum as a recording material carrier, which is driven to rotate counterclockwise with respect to the photosensitive drum 101 at the same peripheral speed as the photosensitive drum 101.

The document 103 is scanned by a document illumination lamp 104, and a first mirror 105, a second mirror 106,
The reflected light is bent by the mirror 107 and the lens 1
In the case of a full-color original that is read as an image by the photoelectric sensor 109 after the focus is adjusted by 08, a magenta component, a cyan component, a yellow component,
Four scanning operations are performed to read the black component.

First, a laser beam is emitted from a laser transmitter 110 in accordance with the magenta component image read by the photoelectric sensor 109, and a rotating polygon 111 forms a latent image in a scanning direction via a mirror 112. It is formed on the photosensitive drum 101. Then, the toner image is developed by the magenta developing device 113 as a toner image.

On the other hand, transfer paper includes an upper cassette 117, an interrupting cassette 119, a lower cassette 121,
23, but will be described using the lower cassette 121 now.

The transfer sheets stacked in the lower cassette 121 are separated one by one in a sheet separation unit 122.
Vertical path rollers 124, 125, 126, horizontal path roller 1
27, the sheet is conveyed by the pre-registration roller 128 to the registration roller 6 as supply means.

Then, the transfer paper is conveyed to the transfer drum 1 after the timing is adjusted by the registration roller 6 so that the image position on the photosensitive drum 101 and the position of the transfer paper in the transfer unit 131 match. Then, the transfer paper is electrostatically adsorbed onto the transfer drum 1 by an adsorption roller 2 as an adsorption unit.

Next, in the transfer section 131, the photosensitive drum 1
Magenta toner image developed on the transfer drum 1
The image is transferred to the transfer paper adsorbed thereon.

Then, the transfer paper rotates while being adsorbed on the transfer drum 1 as it is. The toner remaining on the photosensitive drum 101 without being transferred by the transfer unit 131 is a cleaner 135
Collected at

Then, the photosensitive drum 1 is charged by the primary charger 136.
After the potential on 01 is made uniform, a latent image corresponding to the cyan component image is formed on the photosensitive drum 101 by the same process as that for the magenta component image, and is developed as a toner image by the cyan developing device 114. Then, the transfer unit 131
The cyan toner image is transferred onto the transfer paper that has been attracted onto the transfer drum 1 that has made one rotation.

Similarly, the image of the yellow component and the image of the black component are sequentially transferred onto the transfer paper in a superimposed manner. Incidentally, 115 is a yellow developing device and 116 is a black developing device.

Here, it goes without saying that the position of the latent image formed on the photosensitive drum 101 is controlled by the laser beam so that the images of the four color components on the document 103 all coincide on the transfer paper.

The transfer paper onto which the four color toner images have been transferred is separated from the transfer drum 1 by the push-up roller 132 and the separation claw 133 and is conveyed to the fixing device 137 by the conveyance section 134.

In the fixing device 137, the heater 144
Roller 143 and heater 1 heated by
The transfer paper is nipped and conveyed by the roller pair of the pressure roller 145 heated by 46, and the unfixed toner image carried on the transfer paper is melted and fixed on the transfer paper.

Thereafter, the transfer paper is discharged out of the image forming apparatus main body by the discharge roller 139, and is stacked on the tray 147.

In the case of double-sided copying, the transfer paper that has passed through the fixing device 137 after the front side copying is completed is deflected in the paper passing direction by the flapper 138 without being discharged to the outside of the image forming apparatus main body. After being conveyed by 150, and turned upside down by the reversing section 140, it is stored in the intermediate tray 141.

Then, the sheet is separated one by one in the separation sheet feeding section 142, and the vertical path roller 126 and the horizontal path roller 12 are separated.
7. The sheet is conveyed to the registration roller 6 by the pre-registration roller 128.

After the same process as the front side is completed and the copy on the back side is completed, the transfer paper is discharged out of the image forming apparatus main body by the discharge roller 139 and is stacked on the tray 147.

FIG. 1 is a perspective view showing the positional relationship among the transfer drum 1, the suction roller 2, the left suction guide 3, the right suction guide 4, and the squeezing member 5, which are symmetrical in the longitudinal direction.

FIG. 2 shows a cross section of a transfer paper path between the registration roller pair 6 and the suction roller 2.

The suction roller 2, the right suction guide 4, the left suction guide 3, and the sheet-like ironing member 5 are supported by the front (not shown) and the rear 7 of the suction side plate. The transfer drum 1 can be brought into contact with and separated from the transfer drum 1 by driving means (not shown).

The attraction roller 2 is set so as to come into contact with the transfer drum 1 only during the operation of attracting the transfer paper to the transfer drum 1.

First, when the transfer paper is conveyed to the registration roller pair 6, the registration roller pair 6 is moved by the CPU (not shown) at the timing when the front end of the transfer paper coincides with the front end of the toner image formed on the photosensitive drum 101. To start driving.

Then, the transfer paper is supplied to the left and right suction guides 3 and 4.
Thus, the guide member 5 is guided to the contact portion 9 formed by the contact of the ironing member 5 with the left suction guide 3 (FIG. 1).
3).

The transfer paper having a wavy shape as shown in FIG. 3 due to moisture absorption or the like still has a wavy shape even after passing through the nip portion of the two registration roller pairs 6 extending in the longitudinal direction. I have.

This is because the pair of registration rollers 6 has no function of extending the transfer paper in the longitudinal direction, and the pair of registration rollers 6 is in contact with a certain amount of pressure, so that the transfer paper is not nipped by the pair of registration rollers 6. This is because they cannot be displaced in the longitudinal direction at

After passing through the nip portion of the registration roller pair 6,
The transfer paper guided to the contact portion 9 is stretched in the longitudinal direction by passing through the contact portion 9, and the waving is corrected (FIG. 5).

Then, while being stretched, it is guided to the nip between the transfer drum 1 and the suction roller 2 by the left suction guide 3 and the right suction guide 4, and is sucked onto the transfer drum 1. When the rear end of the transfer paper passes through the nip between the suction roller 2 and the transfer drum 1 and the entire area of the transfer paper is completely sucked onto the transfer drum 1, the suction roller 2 separates from the transfer drum 1 and is transferred onto the transfer paper. Prevents toner from disturbing the image.

Here, the sheet-like squeezing member 5 in the present embodiment has sufficient elastic force when elastically deformed to correct the waving, and buckles, delays,
The size is set so as not to cause a jam or the like.

Therefore, in the present embodiment, a SUS plate having a thickness of 100 to 300 μm or a polyethylene terephthalate (PET) sheet having a thickness of 100 to 500 μm is used as the ironing member 5.

In this embodiment, the ironing member 5 is
Although provided between the registration roller pair 6 and the suction roller 2, that is, immediately before the suction roller 2, the cassettes 117, 119,
It may be provided on a transfer paper path from a paper feed unit such as 121, the intermediate tray 141, and the multi-manual feed 123 to the suction roller 2.

However, the transfer paper whose wave has been corrected may generate wave again after a lapse of time. Therefore, it is preferable to provide the ironing member 5 immediately before the suction roller 2 as in this embodiment.

Further, in the present embodiment, the squeezing member 5 is provided in the whole area in the longitudinal direction. However, the squeezing member 5 shorter than the length of the transfer paper in the longitudinal direction is provided only in the central portion of the transfer paper, and the transfer paper is squeezed. Even if it does, by extending the waving of the central part to the outside, the area where the ironing member 5 is not in contact,
That is, the waving generated in the area outside the transfer paper is also pushed outward, and the same effect can be obtained.

Further, as shown in FIGS. 14, 15 and 16, a squeezing member 5 is provided immediately before the attraction roller 2 so that the transfer paper is extended in the longitudinal direction and is attracted from the central portion of the transfer paper. By doing so, it is more effective.

FIG. 14 is a perspective view thereof, FIG. 15 is a cross-sectional view showing a state at the center, and FIG. 16 is a cross-sectional view showing a state near an end.

(Second Embodiment) The present embodiment and the second embodiment will be described below.

FIG. 12 is a structural view showing the vicinity of the suction roller 2 according to this embodiment. The other device configuration is the same as that of the first embodiment.

In this embodiment, a sheet-like ironing member 5 is fixed to the right suction guide 4 as in the first embodiment.

The left suction guide 3 includes a base 3a and sheet members 3b and 3d fixed to the base. The sheet member 3b extends to the suction roller 2 to guide the transfer paper to the suction roller 2. Further, the sheet member 3d is in contact with the ironing member 5 and is deformed as shown in the drawing.
Further, the ironing member 5 is in contact with the sheet member 3a via the reinforcing sheet member 3c.

The squeezing member 5 may be provided over the entire area in the longitudinal direction as in the first embodiment, or may be provided so as to press only the central portion of the transfer paper.

The suction roller 2 can be separated from and connected to the transfer drum 1, and is located at a position separated from the transfer drum 1 in FIG.

In this embodiment, the supplied transfer paper is corrected for waving by the ironing member 5 and the sheet member 3d.
Further, the waving is also corrected at the contact portion between the ironing member 5 and the reinforcing sheet member 3c.

The ironing member 5, the sheet members 3b, 3
d, the reinforcing sheet member 3c is made of polyethylene terephthalate resin.

(Third Embodiment) In the first embodiment, an ironing member 5 is provided, and the corrugation of the transfer paper is caused to pass in the longitudinal direction by passing through a contact portion 9 between the ironing member 5 and the left suction guide 3. In the third embodiment, a configuration is proposed in which the registration roller is formed in a crown shape to extend the wavy of the transfer sheet in the longitudinal direction.

The registration roller pair 6 is composed of two rollers 6a and 6b (FIG. 7), and is driven to rotate by driving means (not shown).

By processing at least one of the two rollers (6a in FIG. 7) into a crown shape,
The transfer paper is pulled outward in the shape of a crown.

By doing so, the waving of the transfer paper is elongated in the longitudinal direction (FIG. 6).
It is guided by the left suction guide 3 and the right suction guide 4 and is sucked onto the transfer drum 1 by the suction roller 2.

Here, at least one of the registration rollers is formed into a crown shape. However, it is preferable that a high-conveyance-side roller, for example, a rubber roller side be formed into a crown shape.

In this embodiment, at least one of the pair of registration rollers 6 is formed into a crown shape.
The pair of rollers is not limited to the pair of registration rollers, but is a pair of rollers that influence the transfer paper path from a paper supply unit such as the cassette 117, 119, 121, the intermediate tray 141, or the multi-bypass tray 123 to the suction roller 2, for example, A similar effect can be obtained by processing at least one of the front roller 128 and the vertical pass rollers 124, 125, 126 into a crown shape.

Although the roller pair is a continuous roller in the longitudinal direction here, a roller pair formed in the longitudinal direction as a cluster as shown in FIG. 8 may be used.

(Fourth Embodiment) In the fourth embodiment, the pre-registration roller is composed of two pairs of skew rollers 11 and 12 as shown in FIG. A configuration is proposed in which the skew of the transfer sheet is lengthened in the longitudinal direction by providing the back side skew roller pair 11 in a direction in which the transfer sheet is skewed outward.

Drive is input to the input gear 12 in the figure from drive means (not shown). This drive is transmitted to the front skew roller by the gears 13 and 15 via the drive shaft 19 and to the rear skew roller by the gears 14 and 16. The drive is transmitted to the opposing rollers (not shown) by the gears 17 and 18, respectively, and the front skew roller pair 10 and the rear skew roller pair 1 are transmitted.
1 are driven to rotate at the same peripheral speed.

When the transfer paper is conveyed to the pre-registration roller, the transfer paper is simultaneously nipped by the skew roller pairs 11 and 12, and the front half of the transfer paper in the longitudinal direction is moved by the front skew roller pair 10. To the front side, the back half is the back side skew roller pair 1
1, the transfer paper is conveyed in an elongated manner (FIG. 10).

Then, the transfer paper is conveyed in such a state that the waving is stretched, and the registration roller pair 6 sets the timing so that the leading edge of the image coincides with the leading edge of the transfer paper.
It is guided by the left suction guide 3 and the right suction guide 4 and is sucked onto the transfer drum 1 by the suction roller 2.

Here, the pre-registration roller pair is constituted by two skew roller pairs. However, the cassette 11 such as the registration roller pair 6 and the vertical path roller pairs 124, 125, 126, etc.
7, 119, 121, the intermediate tray 141 or the multi-manual feed 123, and any one of the roller pairs existing on the transfer paper path from the paper feeding unit to the suction roller 2 is skewed by the above two sets. The same effect can be obtained by using a roller pair.

[0067]

As described above, according to the present invention, the recording material supplied to the recording material carrier is stretched in a direction perpendicular to the moving direction of the recording material, so that the recording material can be evenly distributed on the recording material carrier. And a good image can be formed on the recording material carried on the recording material carrier.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a positional relationship among a transfer drum, a suction roller, a left suction guide, a right suction guide, and an ironing member.

FIG. 2 is a cross-sectional view of a transfer paper path between a registration roller and a suction roller.

FIG. 3 is a perspective view showing a state where transfer paper is waving.

FIG. 4 is a cross-sectional view illustrating a state in which transfer paper is partially floating above the transfer drum due to waving on the transfer drum.

FIG. 5 is a perspective view showing that the waving of the transfer paper is elongated by an ironing member.

FIG. 6 is a perspective view showing that the corrugation of the transfer paper is elongated by a pair of resist rollers processed into a crown shape.

FIG. 7 is a view showing a pair of registration rollers processed into a crown shape.

FIG. 8 is a view showing a pair of registration rollers formed in a crown shape.

FIG. 9 is a diagram showing two skew roller pairs.

FIG. 10 is a perspective view showing that the undulation of the transfer sheet is extended by two pairs of skew rollers.

FIG. 11 is a schematic sectional view of an image forming apparatus main body.

FIG. 12 is a cross-sectional view of the vicinity of a suction unit.

FIG. 13 is an enlarged view of a nip portion between the left suction guide and the ironing member when the ironing member is formed of an elastic member.

FIG. 14 is a perspective view of a suction unit provided when an ironing member is provided only at a central portion and a transfer sheet is attracted to a transfer drum from the central portion;

FIG. 15 is a sectional view (center portion) of FIG. 14;

16 is a sectional view of FIG. 14 (near an end).

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 transfer drum 2 suction roller 3 left suction guide 4 right suction guide 5 ironing member 6 registration roller 7 after suction side plate 8 swing center 9 gap between left suction guide and ironing member 10 front skew roller pair 11 back skew Roller pair

Claims (5)

(57) [Claims] 1. A recording material carrier for supporting a recording material, an adsorption unit for electrostatically adhering the recording material to the recording material carrier, a supply unit for supplying the recording material to the adsorption unit, An image forming means for forming an image on a recording material carried by a material carrier, wherein the moving direction of the recording material is between the supply means and the suction means in the moving direction of the recording material. An ironing member that is shorter than the length of the recording material in a direction perpendicular to the recording material and presses a central portion of the recording material in a direction perpendicular to the moving direction of the recording material toward the recording material carrier. Image forming device. 2. The image forming apparatus according to claim 1, further comprising a sheet member disposed to face the ironing member and receiving pressure from the ironing member. 3. The image forming apparatus according to claim 1, wherein the ironing member is a sheet-shaped member. 4. The image forming means includes: an image carrier for carrying an image; and a transfer charger for transferring an image carried on the image carrier to a recording material carried on the recording material carrier. The image forming apparatus according to claim 1, further comprising: 5. The image forming apparatus according to claim 4, wherein a plurality of images are sequentially transferred onto the recording material carried on the recording material carrier.