JPH01292376A - Transfer material separating device for image forming device - Google Patents

Abstract

PURPOSE:To prevent a member from damaging, to prolong its life, and to stop deterioration in picture quality by detecting the thickness of a transfer material and making a separation claw abut on an image carrier or a roller for fixation at need. CONSTITUTION:A transfer electrostatic charger 3 is provided in parallel to the image carrier 1 which rotates as shown by an arrow A and a toner image formed on the surface of the image carrier reaches a transfer position facing the electrostatic charger 3 as the image carrier 1 rotates. Then the transfer material which moves forth through a conveyance path 2 as shown by an arrow B while timed with the toner image through the operation of a resist roller couple 8 also reaches the position to abut on the image carrier 1 and the toner image is transferred from the image carrier 1 to the transfer material at said position through the operation of the electrostatic charger 3. Then the transfer material which carries the toner image is separated from the image carrier 1 through the operation of a separation electrostatic charger 4 and further a separation claw 5 at need and then supplied to a fixation position through the conveyance path 7.

Description

Detailed Description of the Invention (1) Object of the Invention (Field of Industrial Application) The present invention relates to an image forming apparatus that uses an electrostatic transfer process, such as an electrostatic copying machine or a printer, and particularly to a transfer material separation device thereof. It is something.

(Prior art and problems to be solved) A transferable toner image formed on the surface of an image carrier is brought into contact with a sheet-like transfer material such as paper and transferred to this, and the transfer material carrying this toner image is transferred to the sheet-like transfer material such as paper. An image forming apparatus is configured to fix and fix a toner image on the transfer material by passing the toner image between a pair of rollers that are in pressure contact with each other, and applying pressure or pressure and heat to the transfer material passing by the pair of rollers. It has been well known for a long time.

In such an image forming apparatus, during transfer, the transfer bias applied to the transfer material in order to transfer the toner image on the image carrier side to the transfer material causes the transfer material to be attracted to the image carrier even after the transfer. Since this tends to cause problems such as jams, it has been widely used that the transfer material is actively separated from the image carrier by means such as a separating claw at the post-transfer position. It is put into practical use.

By the way, the separation claw used to separate the transfer material in this way usually has its sharp tip in constant contact with the photosensitive layer on the surface of the image carrier, so there is no risk of damaging this or damaging the photosensitive layer on the surface of the image carrier even after transfer. The residual toner that remains on the image forming apparatus collects on the tip of the separating claw, and this drops onto the transfer material, causing image stains.This also applies to the separating claw on the roller of the fixing device. .

However, paper, which is an ordinary transfer material for which liquids are often used, has a considerable degree of stiffness and elasticity. With the trend toward smaller diameters, so-called curvature separation means can be fully utilized, and the rollers in the fixing device are also relatively small in diameter. carrier,
The disadvantages of keeping the roller in contact with the surface of the roller in the fixing device are becoming more noticeable.

Of course, it is also true that it is not a good idea to completely eliminate separation claws, since thin paper that is weak and for which the presence of one-separation claws is sufficiently effective is certainly used even if it is used less frequently. be.

The present invention has been made to deal with such a situation, by detecting the thickness of the transfer material used and bringing the separating claw into contact with the image carrier or the fixing roller only when necessary. It is an object of the present invention to provide a transfer material separation device that can extend the life of these members and prevent image staining due to the presence of separation claws as much as possible.

(2) Structure of the invention (technical means for solving the problem, its effect) In order to achieve the above object, the present invention provides a moving adsorbed surface on which the transfer material is adsorbed, and an elastic In an image forming apparatus, the image forming apparatus includes a separation claw biased at a position separated from the transfer material, and a detection device located upstream of the separation claw in the traveling direction of the image carrier and detecting the thickness of the transfer material. only if the thickness of is within a preset range.

The device is characterized in that it includes means for bringing the separation claw to an operating position where it comes into contact with the surface to be attracted.

With this configuration, it is possible to reduce as much as possible the time during which the separation claw is in contact with the surface to be attracted, and as a result, maintenance of the device can be simplified and the life of the device can be extended.

(Description of Embodiments) FIG. 1 is a side view of a main part of an image forming apparatus equipped with a rotating cylindrical image bearing member to which the present invention is applied.

A transfer charger 3 is disposed parallel to an image carrier l extending perpendicular to the plane of the paper and rotating in the direction of arrow A, and a toner image is formed on the surface of the image carrier.

As the image carrier rotates, when it reaches the transfer site facing the transfer charger, it is synchronized with the toner image by the action of the registration roller pair 8, and passes through the conveyance path 2 as shown by the arrow B.
A transfer material (not shown) traveling in the direction also reaches the region and comes into contact with the image carrier, and at this position, the toner image is transferred from the image carrier to the transfer material by the action of the transfer charger 3.

Next, the transfer material carrying the toner image is charged by a separation charger 4,
Further, when necessary, the image is separated from the image carrier by the action of the separation claw 5, and is supplied to a fixing site (not shown) through the conveyance path 7.

It should be noted that, as is well known, around the image carrier l, there are arranged a charger, an image signal imparting means, a developing device, a cleaning device, and other members necessary for image formation. Needless to say, they are all omitted since they are not directly related to the present invention.

In the image forming apparatus as described above, in the present invention, a detection device 9 for detecting the thickness of the transfer material is provided attached to the registration roller 8, and the separation claw 5 is linked to the detection device. Therefore, the separation claw is configured to operate only when necessary.

FIG. 2 shows only the vicinity of the registration roller pair 8 and the separating claw 5 in the apparatus shown in FIG.

As shown in the figure, the registration roller pair 8 consists of a lower roller 8b that rotates in a fixed position H-c, and an upper roller 8a that is in pressure contact with the lower roller 8b and can be displaced in the vertical direction in the figure depending on the thickness of the transfer material passing between both rollers. The detection device 9 detects the movement of the lever 9a that comes into contact with the upper roller 8a and rotates together with it.

On the other hand, as shown in Figure 1, the separating claw 5 is connected to a solenoid 6 attached to a fixed position in the device, and a spring 6a causes the tip of the separating claw 5, which is pivotally connected to a pin 5a, to be attached to the image carrier l. biased away from the surface.

The detection device 8 detects that no transfer material is present.

When the upper roller 8a is in contact with the lower roller 8b, and when the thickness exceeds a preset thickness, for example, Omm.
The solenoid 6 is controlled by a control means (not shown) so as to energize the solenoid 6 only when there is a transfer material exceeding 0.08 mm or less.

With this structure, for example, when the equipment is idling or when using a thick and strong transfer material with a thickness of 0.08 m or more, the separating claw 5 is moved back as shown in the second figure. When the transfer material is present, the transfer material separates from the image carrier due to its own elasticity after completing the transfer and advances to the fixing site.

When a transfer material whose thickness is thinner than 0 or QB +n is detected, the solenoid 6 is energized and the tip of the separation claw 5 comes into contact with the surface of the image carrier, so that the material is attracted to the image carrier even after transfer. If there is any transfer material that is mixed, it shall be ensured that it is separated.

Note that it goes without saying that the solenoid does not need to be continuously energized during the time when the transfer material of a predetermined thickness passes through, but when the transfer material reaches the position of the separating claw, after that, it is not necessary to keep it energized continuously. Of course, it is also possible to preset the time up to an appropriate point in time when the information can be confirmed, and thereby perform sequence control in a known manner.

The one shown in the figure uses a detection device that detects the thickness of the transfer material through the displacement of the registration roller to energize and deenergize the solenoid. Of course, it is also possible to directly detect this, or a double feed detection device that is normally installed at this position may be used.

Furthermore, as mentioned above, a pair of rollers are placed in pressure contact with each other, and the transfer material carrying the toner image is passed through the pressure nip portion, and pressure or pressure and heat is applied to fix the toner image on the transfer material. It will be readily understood that the present invention can also be applied to a separating claw for preventing the transfer material from adhering to the roller in a fixing device configured to do so.

FIG. 3 shows another configuration to which the present invention is applied, in which a plurality of separation claws 51 to 54 (four in the illustrated case) are provided to accommodate transfer materials of various widths. It is equipped with accompanying solenoids 61 to 64 and detection devices 91 to 94, and is configured to turn on only the solenoid of the separation claw corresponding to the width of the transfer material passing through.

(3) As described in detail of the invention, in accordance with the present invention, since the separation claw acts only on the transfer material of a thickness considered suitable for use, the separation claw can directly image the image. Since it is possible to limit the time during which the carrier is in contact with the photosensitive layer on the surface of the carrier or the fixing roller to a minimum, damage to these components can be prevented and their lifespan can be extended. Effectively prevents toner from accumulating and falling or adhering to the transfer material, resulting in deterioration of image quality.
It is possible to F.

It can also be used as a sensor to control the writing timing of one image on the transfer material, making it possible to accurately control the position of the image on the transfer material, which is also effective in preventing jams. be.

[Brief explanation of the drawing]

FIG. 1 is a side view of a main part of an image forming apparatus to which the present invention is applied, and FIG. 2 is a side view showing the configuration of the transfer material thickness detection device and separation claw portion. FIG. 3 is a perspective view of essential parts schematically showing an application example of the present invention. l・φΦ image carrier, 21111-transport path, 3@...transfer charger, 5--separation claw, 6-fist solenoid, 8...
- Registration roller pair, 9...Transfer material thickness detection device. Figure 1 Figure 2 WJ Figure 3

Claims (1)

[Scope of Claims] A traveling suction surface on which a transfer material is adsorbed, a separation pawl that is normally biased to a position elastically separated from the surface, and a separation pawl when viewed in the traveling direction of the image carrier. In an image forming apparatus equipped with a detection device located upstream of the transfer material that detects the thickness of the transfer material, only when the thickness of the transfer material is within a preset range,
A transfer material separation device comprising means for bringing the separation claw to an operating position where it comes into contact with the surface to be attracted.