JPH01319077A - Picture forming device - Google Patents

Abstract

PURPOSE:To obtain a high-quality picture by providing a means which temporarily fixes a toner image to a transfer material simultaneously with the transfer at the transferring time. CONSTITUTION:Since bearings 3a and 3b for supporting a transfer roller 3 are loosely put in long holes 9 which are formed in frame bodies F1 and F2 and approximately extended in the axial direction of an image carrier 1, the transfer roller 3 is brought into contact with the image carrier 1 with pressure by springs 7 and 8. The pressure-contacting force of the springs 7 and 8 is set at such a strength that the toner image electrostatically transferred from the image carrier to a transfer material can be temporarily fixed by the pressure-contacting force. Since the toner image is adhered to the transfer material passed through a transferring section 3 with a certain strength, the impact or vibrations received until the transfer material is discharged from this picture forming device or deterioration of the picture quality caused by the disturbance of the toner due to residual electric charges can be prevented and a high-quality picture can be obtained.

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 and a printer thereof.

(Prior art and issue 8 to be solved) A transferable toner image formed on the surface of an image carrier is electrostatically transferred to a sheet-like transfer material such as paper using a transfer charger, a transfer roller, etc. This toner image is 11! 2. Description of the Related Art Image forming apparatuses configured to transport a transfer material held therein to a fixing site and fix and fix a toner image on the transfer material are conventionally well known.

FIG. 3 schematically shows the main parts of a typical image forming apparatus of this type.

A transfer roller 3 is disposed in pressure contact with an image carrier 1 having an axis perpendicular to the plane of the paper and rotating in the direction of arrow A.

When the toner image formed on the image carrier surface l reaches the axial portion where the transfer roller 3 comes into pressure contact with the rotation of the toner image, the transfer material (not shown) supplied from the conveyance path 2 is transferred to the registration roller. The toner image reaches the transfer site in synchronization with the +in toner image through pair 2a, passes through the pressure nip between the image carrier and the transfer roller, and at this time, due to the transfer bias applied to the transfer roller, the toner image Electrostatically transferred to the transfer material.

After passing through the transfer site, the transfer material carrying the toner image electrostatically is supplied to the fixing device 6 by a conveyance path 4 consisting of an endless belt, and is inserted into the nip portion of the fixing a-ra pair 6a that are in pressure contact with each other. At this time, the toner image is fixed and fixed to the transfer material by applying pressure or pressure and heat by the pair of fixing rollers, and is then discharged from the apparatus.

Although not shown in the drawings, there is a primary charger around the image carrier for uniformly Wf''Il! on the surface of the image carrier, and an image biasing device for forming an electrostatic latent image on the primary charger. An image signal applying means for applying a laser beam, a reflected light of the light irradiated on the original, etc., a developing device for supplying toner to this latent image and making it visible, a cleaning device for removing residual toner, etc. It goes without saying that necessary members are provided, but since they are not directly related to the present invention, they are omitted.

As can be easily understood from the configuration of the image forming apparatus described above, the toner image carried on the transfer material at the transfer site is only electrostatically held on the transfer material. for example.

Fluctuations in the residual electric field due to slight vibrations or shocks that occur at the moment when the leading edge of the transfer material bites into the pair of fixing rollers, or after the trailing edge leaves the registration rollers, or when the charge applied during transfer remains afterward. The toner may be scattered or displaced irregularly, disturbing the toner image, resulting in deterioration of image quality.

In order to avoid such drawbacks, as shown in the figure, a fan is placed inside the conveyor belt to attract the transfer material to the fan to stabilize its position, and a static elimination needle is placed at the post-transfer position. A method has been proposed in which the residual charge on the transfer material is removed and the potential is stabilized, but the former method is complicated due to being left in a high temperature, high humidity environment for a long time or processing such as single-sided printing. If the transfer material is curled or bent, the desired effect may not be obtained, and if the static eliminator needle is used for a long period of time, dust or floating toner may accumulate inside the device, reducing its effectiveness. , there is a problem that it must be cleaned regularly.

In addition, each of these means requires a driving device for that purpose,
Since it requires ancillary mechanisms such as a power source, it is not practical for small light field devices that have come into use in recent years.

The present invention has been made in view of the current situation, and has an extremely simple configuration that allows an image forming apparatus such as the one described above to be unaffected by changes in the characteristics and shape of the transfer material and the presence of residual charges. The object of the present invention is to provide a device that can always obtain high-quality images.

(2) Structure of the invention (technical means for solving the problem and its operation) In order to achieve the above object, the present invention comprises an image bearing member and a transfer roller that is in pressure contact with the image carrier, and a pressure nip between the two. An image forming apparatus that performs transfer by inserting a transfer material is characterized in that it is provided with means for temporarily attaching a toner image to the transfer material at the same time as the transfer.

With this configuration, during image formation, it is possible to obtain a high-quality image by preventing disturbance of the toner image carried by the transfer material due to external vibrations, impacts, or the presence of residual charges on the transfer material.

(Explanation of Examples) Figures 1 and 2 are 12! FIG. 3 is an end view and a side view of essential parts of an embodiment in which the present invention is applied to an image forming apparatus having essentially the same configuration as that shown in FIG. 3; FIG.

The shafts of the image bearing member 1 formed in a rotating cylindrical shape and the transfer roller 3 pressed against the image bearing member 1 are attached to a frame disposed within the image forming apparatus, or a side wall thereof in the case of a force-tridge type apparatus. , immovable frame body F1. F2 is pivotally supported by bearings 1a, lb and 3a, 3b.

These bearings extend outside the frame as shown in the figure, and springs 7 and 8 are suspended between the bearings 1a and 3a and between the bearings lb and 3b at the core, and as can be seen from FIG. Bearings 3a and 3b that support the transfer roller 3 are formed in the frames Fl and F2, and have elongated holes 9 extending in the direction of the axis of the image carrier l (only one of which is shown in the figure). Since the transfer roller 3 is a loose fit in the spring 7
．． It is pressed against the image carrier l by the action of 8. The pressing force exerted by the spring 7.8 is set to such an extent that the toner image electrostatically transferred from the image carrier to the transfer material is further temporarily attached by this pressing force.

In this way, the toner image is attached to the transfer material passing through the transfer site with a certain degree of strength, so as mentioned above, the transfer material is transferred from the storage section such as the cassette to the registration rollers, the transfer site, and the conveyor belt. It is possible to prevent deterioration of image quality due to the above-mentioned impact, vibration, or disturbance of the toner due to the presence of residual charge, which the toner receives while passing through the fixing section and before being discharged outside the machine.

Note that as the photosensitive layer on the surface of the image carrier, it is preferable to use an amorphous silicon photoreceptor having high mechanical strength.

Temporary adhesion between the transfer roller and the photoconductor requires not only pressure contact force, but also
It is also possible to make them heat resistant and perform heat fixing, or if sufficient fixing is possible with just the transfer roller and photoreceptor, the fixing device can be omitted and the overall configuration of the device can be miniaturized and simplified. Of course, it is also possible to do so.

(3) Effects of the Invention As can be seen from the above description, in the image forming apparatus that uses a transfer roller to transfer a toner image on an image carrier to a transfer material, the toner image remains to some extent during transfer. Since it firmly adheres to the transfer material, there will be no future deterioration in image quality even if the treatment of residual charges after transfer and the structure of the conveyance means for conveying the transfer material to the fixing site are simplified or omitted.
This is particularly effective in obtaining high-quality images in small and lightweight image forming apparatuses.

[Brief explanation of the drawing]

FIG. 1 is an end view of essential parts showing an embodiment of the present invention, and FIG. 2 is a side view of the same as above.5 FIG. 3 is a side view of essential parts schematically showing the configuration of an image forming apparatus suitable for applying the present invention. be. 1. Image carrier, 2. Fist/conveyance path, 3. Transfer roller, 4. Fist/e conveyance belt, 6.. Fixing device. Figure 1 Figure 2

Claims (1)

[Claims] In an image forming apparatus that includes an image bearing member and a transfer roller that is in pressure contact with the image carrier, and performs transfer by inserting a transfer material into the nip between the two, the toner image is transferred simultaneously with the transfer. An image forming apparatus comprising a means for temporarily attaching a transfer material to a transfer material.