JPS6343473Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a transfer material guide device, and more specifically, the present invention relates to a transfer material guide device, and more specifically, a movable image carrier of an image forming apparatus that transfers and utilizes a developed image formed on an image carrier onto a transfer material. The present invention relates to a device for guiding a transfer material to a body surface.

In image forming devices such as electrophotographic copying devices,
A latent image is formed using an image carrier such as a photoreceptor, an insulator, or a magnetic material, and by electrophotography, electrostatic recording, or magnetic recording, depending on the characteristics of each image carrier. The formed latent image is generally developed into a visible image and transferred to a transfer material for use.
In such an image forming apparatus, a transfer material is guided to the surface of an image carrier by a transfer material guide device and subjected to transfer.

The image quality of the transferred image on the transfer material is greatly influenced by the guiding conditions of the transfer material guide device, but conventionally, in order to achieve a suitable transfer, the transfer material is placed on the surface of the image carrier at a steep angle in front of the transfer position. Transfer material guide devices configured to guide transfer materials have been widely used. The advantage of doing this is that the adhesion between the transfer material and the surface of the image carrier is good, and even in the case of corona transfer, there is no risk that the transfer material will become too charged before the transfer position, so unnecessary developer non-adhesion can be avoided. This is because it does not occur.

However, in such a conventional transfer material guide device, when a stiff transfer material is used, image shift or transfer failure sometimes occurs at the trailing edge of the transfer material, resulting in a loss of image quality. There are belt-shaped image carriers and drum-shaped image carriers, and the above-mentioned accidents occur particularly frequently when the image carrier is drum-shaped.

The present invention has been developed in view of the above-mentioned points, and provides a transfer material guide device that is capable of reliably guiding the transfer material to the surface of an image carrier to a position where good transfer is achieved. It is.

Hereinafter, details of the present invention will be explained using specific examples with reference to the drawings.

FIG. 1 is a schematic diagram illustrating a conventional transfer material guide device, which is the basis of the improvement of the present invention. Reference numeral 1 denotes an image carrier such as a photoreceptor drum, which is moving in the direction of the arrow. A latent image is formed on the surface of the image carrier by a latent image forming device (not shown), and then a developed image is formed by a developing device. Reference numeral 2 denotes a pair of register rollers that feed the transfer material onto the surface of the image carrier in synchronization with the passage of the developed image forming area on the surface of the image carrier. The transfer material guide member includes an upper guide member (front side guide member) 3 that guides the surface side of the transfer material;
It has a lower guide member (back side guide member) 4 that guides the back side of the transfer material. Reference numeral 5 denotes a transfer corona discharger, and 6 and 7 are parts of a transfer material separation means, including a separation belt (not shown), a separation roller 6 and a presser roller 7 for emphasis.

The transfer material is attached to the image carrier with the maximum angle θ formed by the extension line of the guide surface of the transfer material lower guide member 4 and the surface surface line at the point where the extension line intersects with the image carrier surface. sent to the surface. (Indicated by broken line) Then, the leading edge of the transfer material passes through the transfer position and moves along a separation belt (not shown) from the surface of the image carrier to the separation roller position. In this way, after the transfer material leaves the guide member, it passes through the transfer position and
The portion of the transfer material passing through the separation roller 6 position is on the dashed line L. On the other hand, the tip of the transfer material guide member 4 is located above the dotted chain line L, so if the transfer material is stiff like a thick letter, the rear end of the transfer material guide member 4 may exceed the tip of the transfer material lower guide member 4. Sometimes, it will fall to the position of the dashed dotted line L. The shock of this falling transfer material causes image shift in the transferred image, and also makes it difficult to adhere to the surface of the image carrier near the rear end.

Therefore, FIG. 2 is a partially enlarged view of the transfer material lower guide member based on the present invention, and FIG. 3 is a perspective view thereof. In this illustrated example, the tip of the lower transfer material guide member is connected to a protrusion (first portion) 4b whose tip faces the image carrier, and whose tip is located in the direction of movement of the image carrier than the tip of the protrusion 4b. A protruding portion (a protruding portion (a second portion) that extends curvedly along the moving direction of the image carrier and has its tip downstream of the tip of the first portion with respect to the moving direction of the transfer material. ) 4a.

In this way, by providing the protrusion 4b, the gap between the tip of the protrusion 4b and the surface of the image carrier can be brought close to the optimum distance a for intimate contact with the transfer material, and the trajectory of the transfer material entering the surface of the image carrier is indicated by the broken line. It will look like 8.
Incidentally, the optimum distance a is approximately 0.7 to 1.5 mm in the illustrated example.

On the other hand, even if the predetermined distance a is maintained at the tip of the protrusion 4b, the actual movement of the rear end of the transfer material after passing the tip of the protrusion 4b is as shown by the broken line 9, and the rear end of the transfer material is moved from the protrusion 4a. move guided by. That is, the protruding portion 4a prevents the rear end of the transfer material from falling suddenly, and guides the vicinity of the rear end of the transfer material smoothly and reliably to the surface of the image carrier in the same way as other parts of the transfer material. It is something. In particular, the lower guide member is made of a metal plate,
When the protruding portion 4a in the direction of movement of the image carrier is formed by bending the tip of the metal plate, the curved portion is rounded on the side of the transfer material and does not have an angle. Edge guidance is good.

As described above, by providing the protrusions 4a and 4b at the tip of the lower guide member, the tip of the protrusion 4b guides the transfer material from the back side of the transfer material to ensure that the transfer material reaches the surface of the image carrier. In addition, after the movement of the transfer material progresses and the rear end of the transfer material separates from the tip of the protrusion 4b, the rear end of the transfer material is received by the protrusion 4a, and the rear end of the transfer material is held on the protrusion 4a. The transfer material can be moved by being guided. Therefore, it is possible to prevent image shift and transfer defects caused by the rear end of the transfer material suddenly falling from the guide member, and it is possible to obtain a good transferred image on the transfer material.

In order to enable smooth guidance of the transfer material, for example, the tip of the transfer material guide plate having a straight tip is cut and raised at a predetermined gap, so that the curved protrusion 4a is aligned with the transfer material. It is desirable to make the lower guide member so that the extension of the guiding side surface approximately coincides with the ridgeline of the linear protrusion 4b (that is, the corner on the side through which the transfer material passes). It is preferable to prevent the portion from protruding because the gap between the surface of the image carrier and the lower guide member can be accurately determined.

As described above in detail in the specific examples, the device of the present invention:
It is extremely excellent in that it can reliably guide the transfer material to the surface of the image carrier and ensure good transfer. In particular, this apparatus uses a drum-shaped image carrier, and the smaller the diameter of the drum, the greater the effect.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram illustrating a conventional transfer material guide device, which is the basis of the improvement of the present invention. FIG. 2 is a partially enlarged view illustrating an embodiment based on the present invention. Third
The figure is a perspective view of the guide member of the embodiment of FIG. 2. In the figure, 1: image carrier, 2: register roller, 3: transfer material upper guide member, 4: transfer material lower guide member, 5: transfer corona discharger, 6: separation roller, 7: auxiliary roller.

Claims (1)

[Scope of utility model registration request] In order to transfer the developed image formed on the moving image carrier onto the transfer material, a transfer material is provided on the upstream side of the transfer means with respect to the moving direction of the image carrier, and guides the transfer material to the surface of the image carrier. The guide device includes a front side guide member that guides the transfer material on the front side of the transfer material to which the developed image is to be transferred, and a back side guide member that guides the transfer material on the back side of the transfer material, and the back side guide member A first portion whose tip faces the image carrier, and a portion downstream of the tip of the first portion in the direction of movement of the image carrier; The direction of the movement of the transfer material is curved and extends along the direction, and the first
A transfer material guide device comprising: a second portion having a distal end downstream of the distal end of the portion.