JPH0355586A - Transfer device - Google Patents

Abstract

PURPOSE:To eliminate the position shift between a toner image on a photosensitive body and a sheet material on a sheet material carrier and to prevent an image transferred to the sheet material from slurring in color by setting an abutting angle to <=40 deg. to a tangent passing the abutting position of a sheet material carrier. CONSTITUTION:A conveying means 4 conveys the sheet material P such as transfer paper to a sheet material carrier 1 such as a transfer drum and makes the sheet material P abut on a position within a range from the contact position A between the sheet material carrier 1 and an attracting means 3 to nearby its upstream side at a small abutting angle theta1 of <=40 deg., so the sheet material P is prevented from deforming when abutting, attracted electrostatically to the sheet material carrier 1, and held. Consequently, a position shift is prevented from being generated between the toner image on the image carrier and the sheet material on the sheet material carrier 1 and even when plural color toner images are transferred one over another, color slurring is precluded to reproduce a color image excellently.

Description

DETAILED DESCRIPTION OF THE INVENTION 1. The present invention relates to a transfer device used to transfer a toner image formed on an image carrier onto a sheet material in an image forming apparatus using electrophotography or the like. The present invention relates to a transfer device suitable for use in a color image forming apparatus.

Ai & Tachikatsu 1 As an image forming device using electrophotography, a drum-shaped or endless belt-shaped photoreceptor is continuously rotated.
Electrostatic latent images of multiple colors are sequentially formed on the photosensitive layer on the surface of the photoreceptor using an electrophotographic method, the electrostatic latent images of multiple colors are sequentially developed with color toner, and the multiple color toner images are formed into one color. Each time a color toner image is obtained, the color toner image is repeatedly transferred onto a sheet material such as transfer paper on a transfer drum of a transfer device disposed close to the photoconductor, thus superimposing color toner images of multiple colors on the sheet material. Color image forming apparatuses that obtain color images by transferring are known.

A transfer drum of a transfer device used in such a color image forming apparatus has a configuration as shown in FIG. 5(a).

That is, as shown in FIG. 5(a), the transfer drum 1 has a pair of flanges 31 and 3 arranged concentrically with an interval between them.
2 are connected by a connecting portion 33, and a transfer sheet 34, which is a sheet-like dielectric material, is pasted over the entire surface circumference. A plurality of grippers 35 that can be opened and closed are disposed in the longitudinal direction of the connecting portion 33, and each of these grippers 35 faces a window 36 provided in a portion of the transfer sheet 34 located at the connecting portion 33. I'm here. The gripper 35 is for gripping the leading end of the transfer paper P, which is a sheet material, conveyed by the conveying means 4. The conveying means 4 includes a pair of registration rollers 5, 5 and upper and lower paper guides 6, 6.

As shown in FIG. 5(b), the leading edge of the transfer paper P is directed toward the gripper 35 of the transfer drum 1, and the transfer paper P is conveyed by the conveyance means 4 in synchronization with the toner image on the photoreceptor.
The leading edge of the transfer paper P is inserted into the open gripper 35, and the leading edge abuts against it. In this state, the gripper 35 is closed and the leading edge of the transfer paper P is gripped. As the transfer drum 1 rotates, the transfer paper P is wound and supported on the transfer drum 1 without being skewed.

When the transfer of the multiple color toner images on the photoconductor is completed and a color image is formed on the transfer paper P onto the transfer paper P supported on the transfer drum 1, the gripper 35 is opened and the transfer paper is removed. The leading end of the paper P is opened, and the transfer paper P is separated from the transfer drum 1 using a separating claw. The separated transfer paper P is conveyed to a fixing section where the image is fixed.

However, in the above transfer device, the leading edge of the transfer paper P is inserted into the gripper 35 by conveying and supplying the leading edge of the transfer paper P toward the gripper 35.
If the leading edge of the transfer paper P is curled or wavy, the gripper 35 may not be able to grip the leading edge of the transfer paper P.

Therefore, even if the leading edge of the transfer paper P is curled or wavy,
In order to enable the gripper 35 to grip the leading edge of the transfer paper P, as shown in FIG.
The leading edge of the transfer paper P is conveyed to a position in front of the gripper 35 of the transfer drum 1, and the leading edge of the transfer paper P is brought into contact with the gripper 35.
A transfer device that is inserted into the device 5 has been proposed and put into practice.

As in the above transfer device, the tip of the transfer paper P is held by a gripper 35.
By guiding the transfer paper P to the gripper 35, the gripper 35 can certainly grip the leading edge of the transfer paper P even if the leading edge of the transfer paper P is curled or wavy.

However, since the leading edge of the transfer paper P is gripped by the gripper 35, an image cannot be formed on the leading edge of the transfer paper P. Furthermore, if the leading edge of the transfer paper P is deformed due to being gripped, the transportability of the transfer paper P after being separated from the transfer drum 1 will be affected.

Furthermore, in order to be able to transfer onto transfer papers P ranging in size from large to small, the number of grippers 35 in the direction of one rotation of the transfer drum must be limited. Even when used, the number of sheets of transfer paper P that can be transferred per rotation of the transfer drum 1 is limited, and it is not possible to improve the transfer efficiency.

These drawbacks occur because the leading edge of the transfer paper P is gripped by the gripper 35, and the same applies to the transfer apparatus shown in FIGS. 5(a) and 5(b). In the case of the transfer device shown in Fig. 6,
Furthermore, there is a disadvantage that the opening/closing mechanism of the gripper 35 becomes complicated.

In view of the above, a transfer device has been proposed in which an adsorption means such as a corona charger is provided in place of the gripper 35, and the transfer paper P is electrostatically adsorbed on the transfer drum 1 and carried thereon. FIG. 7 shows a conventional example.

In Fig. 7, 2 is a corona charger, and corona charger 2
are disposed at predetermined positions within the atmosphere transfer drum 1, and an adsorption roller 3 consisting of an electrode roller is disposed at a position facing the corona charger 2 across the transfer sheet 34.

The transfer paper P is transported and supplied to the transfer drum 1 with its leading edge directed in synchronization with the toner image on the photoreceptor by a transport means 4 consisting of a pair of registration rollers 5, 5 and upper and lower paper guides 6, 6. , position B of the transfer drum 1 center angle θ2 upstream of the contact point A of the transfer drum 1 with the suction roller 3
The transfer drum 1 collides with the tangent passing through position B at an angle θ. The abutting transfer paper P advances along the circumferential surface of the transfer drum 1 to a contact point A, where it is electrostatically attracted onto the transfer drum 1 by the corona charger 2 and the attraction roller 3. As the transfer drum 1 rotates, the transfer paper P is wound and supported on the transfer drum 1 without being skewed. However, the method of supporting the transfer paper P on the transfer drum 1 using electrostatic adsorption as described above can handle transfer paper P ranging from large sizes to small sizes, and can handle small size transfers. In the case of paper P, a plurality of sheets of transfer paper P can be supported on the transfer drum 1 and transferred.

However, in the past, since the angle θ1 of the abutment of the transfer paper P against the transfer drum 1 was large, the deformation of the transfer paper P during the abutment was large. This is especially noticeable when the rigidity of the transfer paper P is low or the thickness is large, and because the amount of deformation of the transfer paper P is too large, the difference between the restored state of the transfer paper P and the toner image on the photoreceptor becomes large. A positional shift may occur between the transfer paper P on the transfer drum l and the transfer paper P on the transfer drum l.

If there is a positional shift as described above, color shift occurs and the color image is cannot be reproduced well.

Therefore, an object of the present invention is to transport a sheet material such as a transfer paper toward a sheet material carrier such as a transfer drum, abut the sheet material, and
When the toner image on the photoreceptor and the sheet material on the sheet material carrier are electrostatically attracted and supported on the sheet material carrier, it is possible to prevent the sheet material from being deformed. It is an object of the present invention to provide a transfer device that can eliminate positional shift of the image and prevent color shift etc. from occurring in an image transferred onto a sheet material.

The above-mentioned objects are achieved by a transfer device according to the present invention. To summarize, the present invention has a sheet material conveyed and abutted to the sheet material carrier by a conveyance means, and is electrostatically adsorbed and supported by the sheet material carrier by an adsorption means, and the sheet material is supported by the sheet material carrier. In a transfer device, the sheet material is transported by a sheet material carrier to a transfer position with an image carrier, and the toner image on the image carrier is transferred onto the sheet material. The position of abutment against the carrier is within the range from the point of contact of the sheet material carrier with the adsorption means to the closest upstream side thereof, and the abutment angle is set to pass through the abutment position of the sheet material carrier. This is a transfer cocoon placement characterized by an angle of 40 degrees or less with respect to the tangent.

Reaching north Examples of the present invention will be described in detail below.

FIG. 1 is a schematic configuration diagram showing a color image forming apparatus equipped with a transfer device according to an embodiment of the present invention, and FIG. 2 is a diagram illustrating the image forming apparatus of FIG. It is an explanatory diagram showing a paper suction part. In FIG. 1, reference numeral 20 denotes a photosensitive drum of a color image forming apparatus. In this image forming apparatus, a primary charger 23 applies a potential to the photosensitive drum 1 to uniformly charge it, and then an optical image 22 is formed on the photosensitive drum 1. irradiation to sequentially form electrostatic latent images of multiple colors, and develop the formed electrostatic latent images by a developer group 21 having multiple color developers to sequentially form multiple color toner images. do. The toner images of multiple colors are sequentially transferred one by one onto the transfer paper P carried on the transfer drum 1 by the transfer charger 7, and the toner images of the multiple colors are superimposed on the transfer paper P in this way to form a color image. An image is formed.

Furthermore, around the photosensitive drum 1, an exposure device 24 for pre-exposing the photosensitive drum 1 and a cleaner 25 for removing residual toner on the photosensitive drum 1 are further provided.

The transfer paper P, on which the above transfer has been completed, is placed between a pair of AC
After the charge is removed using the corona chargers 8 and 9, the transfer paper P is separated by the separating claw 10, and then the transfer paper P is transferred to the conveying means 1l.
is conveyed to a fixing section (not shown), where the image is fixed.

On the other hand, after the transfer sheet 34 is cleaned by the transfer drum cleaner 12, it is prepared for attracting and supporting the next transfer sheet P. The transfer sheet 34 is cleaned effectively by preventing deformation due to the pressing of the transfer drum cleaner 12.
This is done by applying a backup brush 13 to the transfer sheet 34 from the side opposite to the cleaner 12.

According to the present invention, the transfer paper P to the transfer drum 1 of the transfer device
The loading is carried out as follows.

The transfer device of this embodiment, as in the conventional transfer device shown in FIG. A container 2 and a suction roller 3 are provided. The corona charger 2 is provided inside the transfer drum 1,
The suction roller 3 sandwiches the transfer drum 1 and charges the Korana charger 2.
installed on the opposite side.

The registration roller pair 5, 5 absorbs the skew of the transfer paper P, and sends the transfer paper P toward the transfer drum 1 in synchronization with the image on the photosensitive drum 20.

The sent-out transfer paper P is guided toward the transfer drum 1 by upper and lower paper guides 6, and is abutted against the transfer drum 1.

A feature of the present invention is that when the transfer paper P is supported on the transfer drum 1, the transfer paper P is transported by the transport means 4 to the transfer drum 1.
The object is to strike the object under the conditions shown in FIG.

In FIG. 2, point A is the contact position of the transfer drum 1 with the suction roller 3 (also the position of the transfer drum 1 on the line connecting the corona charger 2 and the suction roller 3), and in this embodiment,
The contact position A is located at a center angle θ2=15 degrees of the transfer drum 1 with respect to a vertical line h passing through the center of the transfer drum 1. The position at which the transfer paper P abuts against the transfer drum 1 is within the range from the contact position A to the closest upstream side of the contact position A, which is the contact position A in this embodiment. Also, the angle at which the transfer paper P abuts against the transfer drum 1, that is, the angle between the tangent passing through the abutting position of the transfer drum 1 and the transfer paper P (in this embodiment, the tangent t passing through the contact position A of the transfer drum 1) and the transfer paper P) is 40 degrees or less, preferably 3
It is set to 0 degrees or less, and in this example, it is set to 10 degrees. In the above, the position where the transfer paper P hits the transfer drum l is set within the range from the contact point A with the suction roller 3 of the transfer drum 1 to the closest upstream side thereof. The abutting is possible at the contact position A or a position upstream thereof, and at the upstream position away from the contact position A of the transfer drum 1, the abutted transfer paper P can be brought into contact with the transfer drum 1. This is because the distance to be guided along the circumferential surface to the corona charger 2 and suction roller 3 at the contact position A is too long, making it difficult to guide.

Also, the angle θ, at which the transfer paper P hits the transfer drum 1, is set to 4.
The reason for setting it below 0 degrees is that if the abutment angle θ1 exceeds 40 degrees, the deformation of the transfer paper P will be large, and if the transfer paper P has no rigidity or is thick, the amount of deformation of the transfer paper P will be large. It becomes too much, and the difference from when the transfer paper P was restored becomes large.
This is because a positional shift occurs between the toner image on the photoreceptor 20 and the transfer paper P on the transfer drum 1.

The transfer paper P conveyed and abutted against the transfer drum 1 by the conveyance means 4 under the above conditions is transferred to the transfer drum 1 by the corona charger 2 and suction roller 3, as in the case of the conventional transfer device shown in FIG. is electrostatically adsorbed and supported.

The corona charger 2 electrostatically attracts and holds the abutted transfer paper P on the transfer drum 1. At that time, the suction roller 3. The electrostatically attracted transfer paper P is uniformly pressed against the transfer drum 1 by electrostatic force, and the adhesion of the transfer paper P to the transfer drum 1 is made higher. By rotating the transfer drum once while performing electrostatic attraction by the corona charger 2 and the attraction roller 3, the transfer paper P is wound and supported on the transfer drum 1 without being skewed. The transfer device of this embodiment is configured as described above, and the transfer means 4 conveys the transfer paper P to the transfer drum l, and covers the range from the contact point A of the transfer drum 1 with the suction roller 3 to the nearest upstream side thereof. Since the transfer paper P is abutted against the inside position at the abutment angle θ1, the transfer paper P can be prevented from being deformed during the abutment, and the transfer paper P can be electrostatically attracted to the transfer drum l and carried. can. Therefore, it is possible to prevent positional misalignment between the toner image on the photosensitive drum 20 and the transfer paper P on the transfer drum 1. Therefore, even if multiple color toner images are transferred in a superimposed manner, color misregistration can be prevented. can reproduce color images well. In addition, in order to improve the work efficiency when pasting the transfer sheet to the transfer drum 1, the pasting of the transfer sheet 34 to the connecting portion 33 of the transfer drum 1 shown in FIG. 5(a) is done using double-sided tape or the like. The flange portion 31 of the transfer drum 1,
A method of not pasting the transfer sheet 34 onto the transfer sheet 32 is conceivable, but since there is no restraint on both ends of the transfer sheet 34 in the width direction, normally the transfer sheet 34 is stuck against the transfer sheet P. The deformation of is large. However, according to the present invention, since the angle θ1 at which the transfer sheet P abuts against the transfer drum 1 is set to a small angle of 40 degrees or less, it is possible to improve the workability of pasting the transfer sheet 34 as described above. However, deformation of the transfer sheet 34 due to the abutting of the transfer paper P can be prevented, and therefore, a color image can be reproduced without color shift due to transfer. FIG. 3 is a schematic configuration diagram showing a color image forming apparatus equipped with a transfer device according to another embodiment of the present invention, and FIG. FIG. 2 is an explanatory diagram showing a suction section for transfer paper. This transfer device has an adsorption roller 3 for assisting the corona charger 2.
Unlike the transfer apparatus shown in FIGS. 1 and 2 in that an auxiliary corona charger 14 is used instead of the auxiliary corona charger 14, the contact point A of the transfer drum 1 with the adsorption means is located between the corona charger 2 and the auxiliary corona charger l.
The position of the transfer drum 1 is taken on the line g connecting 4 and 4. The other structures are basically the same, and in Figures 3 and 4, the first
~2 The same symbols as those in Figure 2 indicate the same members.
The auxiliary corona charger 14 is transported by the transport means 4,
The transfer paper P that has been abutted against the transfer drum 1 is pressed against the transfer drum l by electrostatic force in the same way as the suction roller 3, and the corona charger 2 electrostatically attracts the transfer paper P to the transfer drum l. It should be of high quality. A lid-shaped guide l is provided on the auxiliary corona charger l4 to prevent the transfer paper P from entering the charger 14 and prevent leakage and ignition.
5 is covered. The transfer device of this embodiment is constructed as described above, and the transfer means 4 conveys the transfer paper P to the transfer drum l, and the contact point A of the transfer drum 1 with the corona charger 2 and the auxiliary corona charger 14 is In a position within the range from to the nearest upstream side,
Since the transfer paper P is abutted at the abutment angle θ, the first to second
As in the case of the transfer device shown in the figure, the transfer paper P can be electrostatically attracted to the transfer drum 1 and carried while preventing the transfer paper P from being deformed during abutment. Therefore, it is possible to similarly prevent positional misalignment between the toner image on the photosensitive drum 20 and the transfer paper P on the transfer drum 1. It is possible to prevent color images and reproduce color images well. In the above embodiments, the transfer device is used in a single color image forming device, but the present invention is not limited to this, and is equally applicable to a transfer device used in a single color image forming device. .

Menwaza A1 As explained above, in the transfer device of the present invention, the conveyance means conveys a sheet material such as a transfer paper to a sheet material carrier such as a transfer drum, and the contact point of the sheet material carrier with the suction means is Since the sheet material is abutted at a small abutment angle of 40 degrees or less at a position within the range from the position to the nearest upstream side, deformation of the sheet material is prevented during abutment, and the sheet material is supported. It can be electrostatically adsorbed and carried on the body.

Therefore, it is possible to prevent misalignment between the toner image on the image carrier and the sheet material on the sheet material carrier. Therefore, even if a plurality of color toner images are superimposed and transferred, color shift can be prevented and a color image can be reproduced satisfactorily.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a color image forming apparatus equipped with a transfer device according to an embodiment of the present invention. FIG. 2 is an explanatory diagram showing a suction portion of the transfer paper to the transfer drum of the transfer device in the image forming apparatus of FIG. 1. FIG. 3 is a schematic configuration diagram showing a color image forming apparatus equipped with a transfer device according to another embodiment of the present invention. FIG. 4 is an explanatory diagram showing a suction portion of the transfer paper to the transfer drum of the transfer device in the image forming apparatus of FIG. 3. FIGS. 5(a) and 5(b) are a perspective view showing a transfer drum of a conventional transfer device and an explanatory view showing a gripping portion of transfer paper by its gripper, respectively. FIG. 6 is an explanatory diagram showing a gripping portion of transfer paper by a gripper of another conventional transfer device. FIG. 7 is an explanatory diagram showing a suction section for the transfer paper to the transfer drum of yet another conventional transfer device. 1: Transfer drum 2: Corona charger 3: Adsorption roller 4: Conveying means 5: Registration roller 6: Paper guide 7: Transfer charger 14: Auxiliary corona charger 20: Photosensitive drum Fig. 5

Claims (1)

[Claims] 1) The sheet material conveyed toward and abutted against the sheet material carrier by the conveyance means is electrostatically attracted and supported by the sheet material carrier by the adsorption means, and the sheet material is carried by the sheet material carrier. In a transfer device configured to transfer a toner image on the image carrier onto the sheet material by transporting the sheet material to a transfer position with an image carrier, the sheet material is projected onto the sheet material carrier by the transport means. The abutment position is within the range from the point of contact of the sheet material carrier with the suction means to the most upstream side thereof, and the abutment angle is 40 degrees with respect to the tangent passing through the abutment position of the sheet material carrier. A transfer device characterized by having the following angle.