JPH04122966A - Image forming device - Google Patents

Abstract

PURPOSE:To previously prevent an accident that a carrying member, etc., are deformed and broken from occurring, and to always form an image with god operability by providing a separation pawl means for separating transfer material, and controlling a separating actuating time through a signal for detecting the tip position of the separation pawl. CONSTITUTION:While toner image on a photosensitive drum is being transferred to the transfer material P attracted to a transfer material carrying member 3, the separation pawl 4 of a transfer material separating device is kept to a position where it is completely retreated from a transferring drum. After or in the midst of transferring a final color, and before the tip of the transfer material P reaches the separation pawl 4, the tip position of the transfer material is detected by a transfer material position sensor disposed inside the transferring drum, and the signal is sent to a stepping motor 11 to drive the motor 11. Thus, a cam 10 is driven, the movement of an abutting roller 8 following on the surface of the cam 10 is controlled, and the separation pawl 4 is moved toward the transferring drum, and the transfer material is separated from the transfer material carrying member 3. When a separating stage is finished, the separating pawl 4 is returned to an original retreated position through the cam 10.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for transferring a developed image (toner image) formed on an image bearing member by an electrophotographic method or an electrostatic recording method to a developed image (toner image) that is held on a transfer material supporting member of a transfer device. The present invention relates to an image forming apparatus that obtains an image by transferring an image to a transfer material, and is particularly characterized by a transfer material separation device that separates the transfer material from a transfer material carrying member that holds and conveys the transfer material by a separation claw means. have

Traditionally, a rotating cylindrical or endless belt-shaped image bearing member such as an electrophotographic photosensitive drum is continuously run, and a photosensitive layer on its surface is subjected to a predetermined image forming process. A color image is obtained by sequentially forming a color toner image using toners of multiple colors, and superimposing and transferring these toner images onto a sheet-like transfer material such as transfer paper held in a transfer device disposed close to the surface of an image carrier. A color image forming apparatus configured as above has been proposed and has already been put into practical use.

The transfer device used in such an image forming apparatus has a fourth transfer device.
As shown in the figure, a pair of ring-shaped rotating members 1 are arranged to face each other on the left and right, and both are integrally connected by a connecting member 2, and a transfer material carrying member 3, which is usually a sheet-like dielectric material, is provided. The transfer drum is constructed by winding and covering the transfer drum.

The transfer drum having such a structure holds the transfer material, which is combined with the toner image on the image carrier in synchronization with the toner image on the image carrier, on the transfer material holding member 3 by electrostatic adsorption force, and each time the drum approaches the image carrier. When the so-called transfer process, in which toner images of each color are received on the transfer material to form a color image, is completed, the transfer material is first transferred to the transfer material holding member 3 in order to separate the transfer material from the transfer material holding member 3. The transfer material is neutralized using a pair of AC corona chargers (not shown) inside the transfer drum, which are disposed facing each other with the transfer material carrying member 3 in between.

Thereafter, the transfer material is separated from the transfer material carrying member 3 by a separation device equipped with separation claw means 4.

In other words, the separation claw drive solenoid 7 is activated, and the separation claw 4
(4a, 4b) are brought close to the transfer drum. That is, when the separation claw drive solenoid 7 is activated, the outer diameter of one or more separation claws 4a, 4b provided on the separation claw handle 5 and the transfer material supporting member rotatably supported at the tip of the separation claw 4a is deformed. The roller 14 rotates using the separation claw fulcrum shaft 6 as a rotation support and contacts the transfer material carrying member 3 with a predetermined contact pressure or a predetermined amount of penetration. The contact pressure or the amount of penetration at this time is adjusted to a constant level by the abutment rollers 8 and the like that follow /111a of the ring-shaped rotating member 1.

At the same time, the rollers 9 for deforming the inner diameter of the transfer material carrying member 3, which are driven from inside the transfer material carrying member 3, do not press against the transfer material carrying member 3 with the same pressure, and locally deform the transfer material carrying member 3. By changing the curvature, the leading end of the transfer material P is lifted, and the separation claw 4 enters the gap, thereby separating the transfer material from the transfer material supporting member 3.

Thereafter, the color toner image transferred onto the transfer material is fixed by a fixing device to obtain a desired color image. After residual toner is removed from the image carrier by a cleaning device, the image carrier is subjected to the image forming process again.

However, as seen in the above conventional example, when the transfer material is held on the transfer material carrying member 3 by electrostatic adsorption force, the holding of the transfer material on the transfer material carrying member 3 is difficult. Misalignment was often experienced.

Furthermore, the amount of penetration of the separating claw 4 and the outer diameter deforming roller 4a into the transfer material supporting member 3 is 41 a of the ring-shaped rotating member 1, and
This is determined by the abutment rollers 8 and the like that follow this, and the amount of advance is always constant at a constant position, so if the holding position of the transfer material with respect to the transfer material supporting member 3 shifts, the transfer material cannot be separated. (This results in transfer material clogging within the main body of the color image forming apparatus, resulting in extremely poor operability.

In addition, there is a drawback that there is a high possibility that unrepairable accidents such as deformation and damage of the separating claw, transfer material supporting member, etc., will occur when dealing with the clogged transfer material.

Therefore, an object of the present invention is to cause the separation claw motion of the transfer material separation device to contact the transfer material carrying member in accordance with the position thereof, thereby reliably separating the transfer material from the transfer device;
Eliminates paper jams, deforms separation claws, transfer material carrying members, etc.
An object of the present invention is to provide an image forming apparatus that can prevent accidents such as breakage and always form images with good operability.

Work to do the section The above object is achieved by an image forming apparatus according to the present invention.

In summary, the present invention includes an image carrier for forming a developed image and a transfer material carrying member, which rotates while holding the transfer material on the transfer material carrying member, and the developed image on the image carrier. In the image forming apparatus, the image forming apparatus includes a transfer device for transferring the transfer material onto the transfer material, and a transfer material separation device for separating the transfer material from the transfer material carrier. The separation claw means is driven to move toward and away from the transfer material carrier and separates the transfer material on the transfer material carrier, and the separation claw means detects the position of the leading edge of the transfer material held on the transfer material carrier. This special image forming apparatus is characterized in that the transfer material separation operation timing is controlled by a signal from a sensor means.

Support 1 Next, the image forming apparatus according to the present invention will be explained in more detail with reference to the drawings.

FIG. 3 shows an embodiment in which the image forming apparatus according to the present invention is implemented in a color electrophotographic apparatus.

In this embodiment, an image bearing member, that is, an electrophotographic photosensitive drum 20 that is rotatably supported and rotates in the direction of the arrow, is uniformly charged by a - wide charger 21, and an exposure means comprising, for example, a laser beam exposure device or the like. Optical image 2 according to image information
2 to form an electrostatic latent image on the photosensitive drum 20. The electrostatic layer image is visualized as a developed image, that is, a toner image, on the photosensitive drum 20 by, for example, a mobile developing device 23.

The mobile developing device 23 includes four developing devices each storing developer of four colors, magenta, cyan, yellow, and black, and these four developing devices 23M and 23C12.
3Y and 23B and a guide (not shown) that can be started horizontally, conveys a desired developing device to a position facing the outer peripheral surface of the photosensitive drum 20, and uses these developing devices. Electrostatic latent images corresponding to each color on the photosensitive drum 20 are developed.

On the other hand, the transfer material P is fed from a cassette or the like, hits the registration rollers 24, is temporarily stopped there, and is sent out to the transfer device at a timing determined by a rotational direction position sensor of the transfer drum or the like.

As shown in FIG. 1, the transfer device has a pair of ring-shaped rotating members 1 that are arranged opposite to each other on the left and right, and are integrally connected by a connecting member 2, which is usually made of a sheet-like dielectric material. The transfer drum has a structure in which a transfer material carrying member 3 is wound and covered.

Returning to FIG. 3, the transfer material P is attracted and held onto the transfer material carrying member 3 by an adsorption device that is provided inside the transfer drum and applies an electric charge of opposite polarity to the toner to the back surface of the transfer material carrying member 3. This is carried out using a corona charger 25 and a conductive roller 26 as a counter electrode arranged opposite to the corona charger 25.

That is, when the grounded conductive roller 26 comes into contact with the transfer material P, charge is injected from the conductive roller 26 to the transfer material P, and the transfer material P is electrostatically attracted to the transfer material carrying member 3 .

The transfer material P attracted to the transfer drum is conveyed according to the rotation of the transfer drum, and the visible image (toner image) of the first color on the photosensitive drum 20 is disposed inside the transfer drum facing the photosensitive drum 20. The toner is transferred onto the transfer material P by applying an electric charge having a polarity opposite to that of the toner to the back surface of the transfer material carrying member 3 using the transfer corona charger 27 . A full-color image is formed by transferring toner images of the second and subsequent colors onto the same transfer material P in the same manner.

After the transfer process is completed, in order to weaken the attraction force of the transfer material P to the transfer material supporting member 3, a pair of AC corona chargers 28 and 29 placed opposite each other with the transfer material supporting member 3 in between are used to charge the transfer material P. Eliminates static electricity. The neutralized transfer material P is separated from the transfer material carrying member 3 by a transfer material separating device having a separating claw means 4, and a corona charger 30 is used to prevent image disturbance due to peeling discharge generated during this time. Perform AC corona charging using

After the separation step, the transfer material P is sent to the fixing device 32 by the conveying section 31, where the toners on the transfer material P are mixed in color and fixed, and then discharged to the outside of the image forming apparatus.

Next, the transfer material separating device used in this embodiment will be described in more detail with reference to FIG.

The transfer material separating device includes a separating claw front side plate 13a and the front side plate 1.
A fulcrum shaft 6 is rotatably supported at both ends by the separating claw front and rear side plates 13a and 13b, and the separating claw support plate 5 is rotatably supported between the front and rear side plates. To support. The separation claw support plate 5 is provided with separation claw means, in this embodiment one or more separation claws 4a, 4b, 4C, and the tip of the first separation claw 4a arranged approximately at the center in the longitudinal direction. , there is a roller 1 for deforming the outer diameter of the transfer material supporting member.
4 is rotatably arranged.

On the other hand, in the longitudinal direction of the separation claw support plate 5, the first separation claw 4
A roller 9 for deforming the inner diameter of the transfer material carrying member is disposed at a predetermined interval on the upstream side in the transfer material conveyance direction on the inside of the transfer drum at approximately the same position as a.

Further, in this embodiment, the separation claw support plate 5 is provided with second and thirty separation claws 4b and 4C at a predetermined interval in the longitudinal direction. The tip position is
The first separation claw 4a is arranged so as to be slightly moved in parallel toward the downstream side in the transfer material conveyance direction from the tip position of the first separation claw 4a.

Further, at least one end of the separation claw support plate 5 is provided with a separation claw 4 at the time of separating the transfer material P on the transfer material carrying member 3.
Abutment rollers 8 are provided to determine predetermined positions of a, 4b, 4C and the transfer drum.

According to this embodiment, the abutment roller 8 is always brought into contact with the cam 10 that controls the movement of the separation claw support plate 5 by the pressure tension spring 16. The cam 10 is driven and controlled by a transfer material position sensor 15 (third
This is done by detecting the leading edge position 1 of the transfer material P using the method shown in FIG.

The contour shape of the cam 10 is formed so that the separation claw 4 moves appropriately in contact with and away from the transfer material carrying member 3 and efficiently separates the transfer material P.

The operation of the transfer material separating device configured as above will be explained below.

According to the present invention, while the toner image on the photosensitive drum 20 is being transferred to the transfer material P adsorbed to the transfer material carrying member 3, the separation claw 4 of the transfer material separation device is at a completely retracted position from the transfer drum. is maintained. Its position is determined by the contour shape of the abutting roller 8 and the cam 10 that is in contact with the roller 8.

After the transfer of the final color is completed, or during the transfer, and before the leading edge of the transfer material P reaches the separating claw 4, the transfer material position sensor a-15 provided inside the transfer drum moves the transfer material. The tip position is detected, and the signal is sent to the stepping motor 11 to drive the stepping motor 11. As a result, the cam lO is driven, and the movement of the roller 8 is controlled by the abutment that follows the surface of the cam 10, and the separating claw 4 is moved toward the transfer drum, and the transfer material P is supported in the manner described above. Separate from member 3.

When the separation process is completed, the separation claw 4 is returned to its original retracted position by the cam 10.

As described above, according to the present invention, the motion of the separation claw 4 of the transfer material separation device can be controlled independently of the transfer drum by the operation of the cam 10, and furthermore, the cam 10 can be controlled by the transfer material position sensor 15. By controlling the holding of the transfer material P to the transfer material carrying member 3 by electrostatic adsorption, even if the holding position of the transfer material P shifts to the extent that the transfer position of the toner image on the transfer material P shifts, the transfer material P can be reliably separated.

Furthermore, according to the present invention, by obtaining optimal separation performance, accidents such as transfer material clogging inside the image forming apparatus are eliminated, and separation claws 4, transfer material carrying member 3, etc. that are caused by conventional transfer material clogging are eliminated. This prevents irreparable accidents such as deformation and damage, and enables highly reliable image formation at all times.

Furthermore, since the abutting roller 8 of the separation claw support plate 5 is made independent of the transfer drum, there is no influence on the rotation of the transfer drum, and the abutting roller 8 and the cam 10 are connected to the pressure tension spring 16.
Since the rollers are always in contact with each other, there is no shock caused by the movement of the abutting rollers 8 towards and away from each other as in the conventional example, eliminating blurring during electrostatic latent image formation and misalignment of transfer of the four colors, resulting in improved color image performance. I can figure it out.

FIG. 2 shows another embodiment of the transfer material separating device according to the present invention.

After passing through a predetermined process similar to the previous embodiment, the transfer material P arrives at the transfer material separation device of this embodiment.

According to this embodiment, a ring-shaped cam 17 is provided at the end of the ring-shaped rotating member 1 of the transfer device.

Further, the ring-shaped cam 17 has a gear formed on its inner surface,
A ring-shaped cam moving gear 18 rotated by a stepping motor 11 is engaged with the gear, and by driving the stepping motor 11, the relative position of the ring-shaped cam 17 and the ring-shaped rotating member 1 in the circumferential direction is adjusted. is controlled.

The structure around the separating claw support plate 5 of the transfer material separating device is the same as that of the first embodiment. However, according to the present embodiment, the abutment roller 8 for positioning the separation claw 4 and the transfer drum is generally held at a position apart from the ring-shaped cam 17 by the tension spring 12, and as needed. The solenoid 7 is actuated accordingly, thereby bringing the contact state into contact.

The ring-shaped cam 17 normally rotates in synchronization with the ring-shaped rotating member 1, but the tip position of the transfer material P is determined by the transfer material position sensor 15 disposed inside the transfer drum, and if the tip position is misaligned, it can be checked. If this occurs, the stepping motor 11 disposed on the ring-shaped rotating member 1 is driven by a signal from the sensor 15, and the ring-shaped cam moving gear 1 is driven.
8, the relative position 1 of the ring-shaped cam 17 with respect to the ring-shaped rotating member 1 is drive-controlled.

The outline shape of the ring-shaped cam 17 is formed so that the separation claw 4 moves appropriately in contact with and away from the transfer material carrying member 3 and efficiently separates the transfer material P.

Further, the separation claw support plate 5 is driven and controlled in its entirety by the 0N10FF of the solenoid 7 in such a manner that it comes into contact with and separates from the transfer drum. That is, while the toner image on the photosensitive drum 20 is being transferred to the transfer material P adsorbed by the transfer material carrying member 3, the separating claw 4 is maintained at a position completely retracted from the transfer drum.

After or during the transfer of the final color, and before the leading edge of the transfer material P reaches the separating claw 4, a transfer material position sensor 15 disposed inside the transfer drum detects the leading edge of the transfer material P. The position is detected and the signal is sent to the stepping motor 11 to drive the stepping motor 11. This drives the ring-shaped cam 17 and sets the cam 17.

Next, the solenoid 7 is activated, and the abutting roller 8 comes into contact with the nongangular cam 17, thereby moving the separating claw 4 toward the transfer drum. The abutting roller 8 separates the transfer material P from the transfer material carrying member 3 in the manner described above while making a driven movement along the cam 17.

When the separation process is completed, the separation claw 4 turns off the solenoid 7.
By being set to F, the tension spring 12 returns it to the original retracted position.

The transfer material separation device of this embodiment can also produce effects similar to those of the above-mentioned embodiments.

1 As explained above, in the image forming apparatus according to the present invention, the movement of the separation claw of the transfer material separation device is controlled by the transfer material position sensor and the cam means which operates independently of the transfer device. Since the transfer material P is controlled, even if the holding position of the transfer material held by electrostatic adsorption on the transfer material carrying member shifts, the transfer material P can be reliably separated, and optimal separation performance can be obtained. This prevents irreparable accidents such as deformation or damage of the separating claw or transfer material carrying member due to transfer material clogging, and enables highly reliable image formation at all times. Further, according to the present invention, by providing the abutment roller independently of the transfer device, the impact on the rotation of the transfer device is eliminated (and the impact caused by the contact and separation movement of the abutment roller is eliminated, thereby There is no blurring during electrostatic latent image formation, transfer misalignment of four colors during color image formation, etc., and there is an advantage that color image performance can be improved.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a transfer device and a transfer material separation device according to an embodiment constructed according to the present invention. FIG. 2 is a perspective view showing a transfer device and a transfer material separation device according to another embodiment constructed according to the present invention. FIG. 3 is a schematic diagram of an embodiment of an image forming apparatus according to the present invention. FIG. 4 is a perspective view showing a conventional transfer device and a transfer material separation device. 1: Ring-shaped rotating member 3: Transfer material carrying member 4: Separation claw means 10: Separation claw drive control cam 17: Separation claw drive control ring-shaped cam FIG.

Claims (1)

[Claims] 1) It has an image carrier that forms a developed image and a transfer material carrying member, which rotates while holding the transfer material on the transfer material carrying member, and transfers the developed image on the image carrier to the transfer material. In an image forming apparatus including a transfer device for transferring and a transfer material separation device for separating the transfer material from the transfer material carrier, the transfer material separation device is driven in contact with and away from the transfer material carrier. is,
The separation claw means separates the transfer material on the transfer material carrier, and the separation claw means detects the leading edge position of the transfer material held on the transfer material carrier by a signal from a sensor means. An image forming apparatus characterized in that transfer material separation operation timing is controlled.