JPH0915985A - Image forming device - Google Patents

Abstract

PURPOSE: To form an excellent image on a recording paper, by extending the recording material fed to the recording material carrier, in the direction orthogonal to the moving direction of the recording material. CONSTITUTION: A transfer paper is guided, by left and right attraction guides 3 and 4, into a contact part formed by holding a squeezing member 5 in contact with the left attraction guide 3. The transfer paper allowed to pass through the nip part of resist rollers pair and guided into the contact part, is extended in the length wise direction in consequence of passing through the contact part and thereby its corrugated shape is straightened. Then, the transfer paper is guided, while left in a state of being extended, into the nip part in-between a transfer drum 1 and a attraction roller 2, by the left attraction guide 3 and the right attraction guide 4, and attracted on the transfer drum 1. When the trailing end of the transfer paper is allowed to pass through the nip in-between the attraction roller 2 and the transfer drum 1, and whole area of the transfer paper is completely attracted onto the transfer drum 1, the transfer roller 2 is separated from the transfer drum 1, in order to prevent the transferred toner image from disturbance.

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 and a laser beam printer using an electrophotographic system. Regarding

[0002]

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

By the way, when the transfer paper is wound around the transfer drum with the tip of the transfer paper held by the gripper provided on the transfer drum, only one transfer paper can be wound around the transfer drum.

Therefore, when the transfer paper is electrostatically attracted to the transfer drum by using a suction roller, the transfer paper is transferred to the transfer drum when the length of the transfer paper in the sheet passing direction is a letter size (about 216 mm) or less. It is practiced to wind two sheets on top at the same time.

[0005]

However, in the above-mentioned conventional example, when the transfer paper is attracted onto the transfer drum, if the transfer paper is wavy as shown in FIG. The part that has become abutting is first contacted and adsorbed to the transfer drum until just before the contact position between the adsorption roller and the transfer drum.

Then, even after a part of the area of the transfer sheet which is concave with respect to the transfer drum has passed the contact position between the suction roller and the transfer drum, the transfer sheet remains floating from the transfer drum. There was an occasion.

If there is a region where the transfer paper floats on the transfer drum, the toner is not efficiently transferred in this region, and there is a defect that the transfer is missing.

FIG. 4 is a cross-sectional view showing a state where the transfer paper is adsorbed on the transfer drum while being wavy. This phenomenon of waviness of the transfer paper occurs remarkably in a high temperature and high humidity environment and when an image is transferred to the second surface of the transfer paper having the image fixed on the first surface.

Therefore, an object of the invention according to the present application is to make the recording material carrier uniformly carry the recording material by extending the corrugation of the recording material before carrying the recording material on the recording material carrier. That is, a good image is formed on this recording material.

[0010]

SUMMARY OF THE INVENTION To achieve the above object, the present invention provides a recording material carrier for carrying and conveying a recording material, and image formation for forming an image on the recording material carried by the recording material carrier. The image forming apparatus having the means includes a stretching means for stretching the recording material supplied to the recording material carrier in a direction orthogonal to the moving direction of the recording material.

[0011]

【Example】

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

In the figure, reference numeral 100 is an image forming apparatus main body.

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

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

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

On the other hand, the transfer sheets are the upper cassette 117, the interruption cassette 119, the lower cassette 121, and the multi-bypass 1
Although it is stacked on 23 or the like, the lower cassette 121 will be described below.

The transfer papers stacked in the lower cassette 121 are separated one by one in the paper feed separating section 122,
Vertical pass rollers 124, 125, 126, horizontal pass roller 1
27, the pre-registration roller 128 conveys the pre-registration roller 128 to the registration roller 6 as a supply unit.

Then, the transfer paper is conveyed to the transfer drum 1 after the timing is adjusted by the registration rollers 6 so that the image position on the photosensitive drum 101 and the position of the transfer paper are aligned in the transfer section 131. Then, the transfer paper is electrostatically adsorbed onto the transfer drum 1 by the adsorbing roller 2 as an adsorbing means.

Next, in the transfer section 131, the photosensitive drum 1
The magenta toner image developed on 01 is transferred onto the transfer drum 1.
It is transferred to the transfer paper that is adsorbed on top.

Then, the transfer paper is rotated 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 cleaned by the 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 image of the cyan component is formed on the photosensitive drum 101 in the same process as the image of the magenta component, 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 attracted on the transfer drum 1 that has rotated once in.

Similarly, the image of the yellow component and the image of the black component are sequentially transferred and superposed on the transfer paper. Incidentally, 115 is a yellow developing device and 116 is a black developing device.

Needless to say, 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 original 103 all match on the transfer paper.

The transfer paper on which the four color toner images have been transferred is separated and 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 conveying section 134.

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

After that, the transfer sheet is discharged to the outside 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, after the copying on the front side, the transfer paper which has passed through the fixing device 137 is not discharged to the outside of the main body of the image forming apparatus, but the flapper 138 deflects the paper passing direction, and the rollers 148, 149. After being conveyed by 150, the front side and the back side are reversed by the reversing unit 140, they are stored in the intermediate tray 141.

Then, the sheets are separated one by one in the separating / feeding section 142, and the vertical pass roller 126 and the horizontal pass roller 12 are separated.
7. The pre-registration roller 128 conveys the registration roller 6.

After the copying on the back side is completed through the same process as the front side, the transfer sheet is discharged from the main body of the image forming apparatus 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 ironing member 5, which have a symmetrical shape 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-shaped squeezing member 5 are supported by the suction side plate front (not shown) and rear 7, and centered around the swing center 8. The transfer drum 1 can be brought into contact with or separated from the transfer drum 1 by a driving unit (not shown).

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

First, when the transfer sheet is conveyed to the registration roller pair 6, the registration roller pair 6 is timing by the CPU (not shown) such that the front end of the transfer sheet and the front end of the toner image formed on the photosensitive drum 101 coincide with each other. Start driving with.

The transfer paper is then attached to the left and right suction guides 3, 4
By this, the left suction guide 3 is guided to an abutting portion 9 formed by abutting the ironing member 5 (FIG. 1).
3).

By the way, the transfer paper having the corrugation as shown in FIG. 3 due to moisture absorption still has the corrugation even after passing through the nip portion of the pair of registration rollers 6 extending in the longitudinal direction. There is.

This is because the registration roller pair 6 does not have a function of extending the transfer sheet in the longitudinal direction and the registration roller pair 6 is in contact with the registration roller pair 6 with a relatively large pressure so that the transfer sheet is nipped by the registration roller pair 6. This is because it is impossible to shift in the longitudinal direction.

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 waviness is corrected (FIG. 5).

Then, in the extended state, 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 trailing edge 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 has been sucked onto the transfer drum 1, the suction roller 2 is separated from the transfer drum 1 and transferred onto the transfer paper. Prevent toner from disturbing the image.

Here, the sheet-shaped ironing member 5 in this embodiment has an elastic force when elastically deformed, which is sufficient to correct waviness, and causes the transfer paper to buckle, delay,
It is set to a size that will not cause jams.

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

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

However, since the transfer paper having the wavy correction may be wavy again with the passage of time, it is preferable to provide the ironing member 5 immediately before the suction roller 2 as in this embodiment.

Further, in this embodiment, the ironing member 5 is provided in the entire longitudinal direction, but the ironing 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 to squeeze the transfer paper. Even if it does, by extending the corrugation of the central portion to the outside, the area where the ironing member 5 is not in contact,
That is, the waviness 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, the squeezing member 5 is provided immediately in front of the suction roller 2 so that the transfer paper is extended in the longitudinal direction and is sucked 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 sectional view showing the state of the central portion, and FIG. 16 is a sectional view showing the state of the vicinity of the end portion.

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

FIG. 12 is a block diagram showing the vicinity of the suction roller 2 of this embodiment. The other device configuration is the same as that of the first embodiment.

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

The left suction guide 3 comprises a base body 3a and sheet members 3b and 3d fixed to the base body. The sheet member 3b extends to the suction roller 2 to guide the transfer paper to the suction roller 2. The sheet member 3d is in contact with the ironing member 5 and is deformed as shown in the figure.
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 brought into and out of contact with the transfer drum 1, and is in a separated position in FIG.

In this embodiment, the supplied transfer paper is undulated by the ironing member 5 and the sheet member 3d,
Further, the waviness 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, the squeezing member 5 is provided, and the abutting portion 9 between the squeezing member 5 and the left suction guide 3 is passed therethrough, whereby the corrugation of the transfer paper is made longitudinal. However, the third embodiment proposes a configuration in which the corrugation of the transfer paper is extended in the longitudinal direction by forming the registration roller into a crown shape.

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

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

By doing this, the corrugation of the transfer paper is extended in the longitudinal direction (FIG. 6), and as it is,
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 has been processed into a crown shape, but it is desirable to process the high-conveyance-force side roller, for example, the rubber roller side into a crown shape.

Further, here, at least one of the pair of registration rollers 6 is processed into a crown shape.
The pair of registration rollers is not limited to any pair, and a pair of rollers such as a register 117, 119, 121, an intermediate tray 141, or a multi-purpose manual feed 123, which are on the transfer sheet path from the sheet feeding section to the suction roller 2, is used. The same effect can be obtained by processing at least one of the front roller 128, the vertical pass rollers 124, 125, 126, etc. into a crown shape.

Although the roller pair is continuous in the longitudinal direction here, it may be a roller pair formed in the longitudinal direction like a dumpling as shown in FIG.

(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. 9, and the front skew roller pair 10 and A configuration is proposed in which both the back side skew roller pair 11 are provided in the direction in which the transfer sheet is skewed outward so that the corrugation of the transfer sheet is extended in the longitudinal direction.

Drive is input to the input gear 12 in the figure from a drive means (not shown). This drive is transmitted via the drive shaft 19 by the gears 13 and 15 to the front skew roller and to the back skew rollers by the gears 14 and 16. Then, 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 back skew roller pair 1 are transmitted.
1 is rotationally driven at the same peripheral speed.

Here, when the transfer sheet is conveyed to the pre-registration roller, the transfer sheet is nipped by the skew roller pairs 11 and 12 at the same time, and the front half of the transfer sheet 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
Since it is pulled to the back side by 1, the corrugation of the transfer sheet is extended and conveyed (FIG. 10).

As it is, the transfer paper is conveyed with the corrugations being stretched, and the registration roller pair 6 makes a timing so that the leading edge of the image and the leading edge of the transfer paper coincide with each other.
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.

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

[0067]

As described above, in the present invention, the recording material carrier is provided with the stretching means for stretching the recording material supplied to the recording material carrier in the direction orthogonal to the moving direction of the recording material. The recording material can be uniformly carried, and a good image can be formed on the recording material carried by 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 the transfer paper is wavy.

FIG. 4 is a cross-sectional view showing a state in which the transfer paper partially floats above the transfer drum due to waviness on the transfer drum.

FIG. 5 is a perspective view showing that the corrugation of the transfer paper is extended by the ironing member.

FIG. 6 is a perspective view showing that a corrugated transfer paper is extended by a pair of crown-shaped registration rollers.

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

FIG. 8 is a view showing a pair of ball-shaped registration rollers processed into a crown shape.

FIG. 9 is a diagram showing two pairs of skew rollers.

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

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

FIG. 12 is a cross-sectional view in 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 made of an elastic member.

FIG. 14 is a perspective view of a suction unit when a squeezing member is provided only in the central portion and the transfer paper is suctioned from the central portion to the transfer drum.

FIG. 15 is a cross-sectional view (central portion) of FIG.

16 is a cross-sectional view of FIG. 14 (around the end).

[Explanation of symbols]

 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 Laura pair

Claims (8)

[Claims] A recording material carrier that carries and conveys the recording material;
In an image forming apparatus having an image forming unit for forming an image on a recording material carried by the recording material carrier, the recording material supplied to the recording material carrier is orthogonal to the moving direction of the recording material. An image forming apparatus comprising: a stretching unit that stretches in a direction. 2. The image forming apparatus is provided with a suction means for electrostatically attracting a recording material to the recording material carrier, and a supply means for supplying the recording material to the adsorption means, and the stretching means is provided. The image forming apparatus according to claim 1, wherein the image forming apparatus is provided between the suction means and the supply means. 3. The image forming apparatus according to claim 1, wherein the stretching means includes a sheet member that presses the recording material. 4. The length of the sheet member is shorter than the length of the recording material in the direction orthogonal to the moving direction of the recording material, and the sheet member is the center of the recording material in the direction orthogonal to the moving direction of the recording material. The image forming apparatus according to claim 3, wherein the portion is pressed. 5. The stretching means includes a pair of rollers for sandwiching a recording material, and at least one roller of the pair of rollers is located at a central portion rather than a diameter of an end portion in a direction orthogonal to a moving direction of the recording material. The image forming apparatus according to claim 1 or 2, wherein the image forming apparatus has a larger diameter. 6. The stretching device according to claim 1 or 2, wherein the stretching means includes two pairs of rollers having an angle with respect to a direction orthogonal to a moving direction of the recording material and nipping the recording material at the same time. The image forming apparatus according to item 2. 7. The image forming means includes an image carrier that carries an image, and a transfer charger that transfers the image carried by the image carrier to the recording material carried by the recording material carrier. The image forming apparatus according to claim 1, further comprising: 8. The image forming apparatus according to claim 7, wherein a plurality of images are sequentially transferred and superposed on the recording material carried by the recording material carrier.