JPH0475068A - Image forming device - Google Patents

Abstract

PURPOSE:To attain the stable carrying properties of a transfer material and to always and stably obtain an image having excellent quality by disposing folding means at least forming one fold on the leading edge part of the transfer material, on the transfer carrying path of the upper stream side compared with a transfer part. CONSTITUTION:A sensor 116D detecting the presence of the transfer material is disposed on carrying guides 55 and 56, on the downstream side of a pair of paper refeeding rollers 116, in the advancing direction of the transfer mate rial. When the sensor 116D detects that the transfer material reaches a pre scribed position, a pressing member 210 A is energized with a solenoid 64 by a MPU for a prescribed time, the projecting part 210a of the pressing member 210A advances to a carrying path, and further, encroaches and projects on an accepting member 210B, and an almost triangle fold shown by a code 3'a is formed on the leading edge of the transfer material passing there. Thus, the separation properties of the transfer material and a photosensitive body are improved, and the occurrence of jamming is avoided to attain the carrying properties.

Description

Detailed Description of the Invention (1) Purpose of the Invention (Field of Industrial Application) This invention relates to an image forming apparatus that uses an electrostatic transfer process, such as an electrostatic copying machine or a printer, The present invention relates to a transfer material conveying device suitable for a conventional image forming apparatus.

(Prior art and problems to be solved) In an image forming apparatus that forms a transferable toner image on the surface of an image carrier and transfers it to a transfer material such as paper, images are formed on both sides of the transfer material, or 2. Description of the Related Art Image forming apparatuses that further form an image on a surface on which an image has been formed are already in widespread use.

FIG. 7 is a side view of the main parts of such an image forming apparatus, and its operation will be briefly described. Transfer material taken out from the cassette 1 or 2 by the paper feed rollers 4 or 5 3' is the conveyor roller pair 6 or 7,
Next, it is guided by a conveyance roller 8, passes through a pair of registration rollers 9, and is transferred to a rotating cylindrical photoreceptor 14 and a transfer charger 10.
and the toner image formed on the surface of the photoreceptor 14 in a well-known manner also reaches the transfer site, and at this time, the toner image applied to the transfer charger is applied to the transfer site. The toner image on the photoreceptor side is transferred to the transfer material.

Thereafter, the transfer material passes through a conveyance path 15 and a fixing device 16 to reach a paper discharge site 17, and if only one printing is to be performed on one side, the transfer material is discharged to the outside as it is.

When performing double-sided/multiple printing, the transfer material exiting the fixing device is guided to the re-feeding section A, and then the roller pair 116
Then, the image forming apparatus passes through the pair of registration rollers 9 again to reach the transfer site, performs the same image forming operation as described above, and after performing the image forming operation a predetermined number of times, is discharged from the apparatus.

By the way, in the image forming apparatus as described above, when the fixing process is completed, whether the fixing action is a heating method or a pressure method, the paper serving as the transfer material inevitably curls.

When carrying out multiple copies as mentioned above, when the transfer paper that has undergone the fixing process is reintroduced to the image forming process, depending on the state of the curl that occurred in the initial process, it may be This inevitably leads to cases where it becomes difficult to separate the photoreceptor from the photoreceptor.

To explain this briefly using the apparatus shown in FIG. 7, when the transfer material shown in the figure is introduced into the transfer site, the curled end portion of the transfer material curves away from the periphery of the photoreceptor 14. If the curled portion is curved in the same direction as the photoreceptor surface, separation becomes extremely difficult due to the electrostatic adsorption tendency of the transfer material to the photoreceptor during transfer. As a result, the transfer material advances along the photoreceptor, causing a jam, resulting in various problems such as operational inefficiency, contamination of various parts within the device due to falling toner, and damage to the device.

The present invention has been made in view of the occurrence of such a situation, and it is possible to prevent curled transfer material by forming irregularities on the leading edge of the transfer material while it is being transported for image formation. However, it is an object of the present invention to provide an image forming apparatus that can easily and reliably separate the transfer material, provide stable conveyance of the transfer material, and consistently produce high-quality images.

(2) Structure of the invention (prior art and problems to be solved) In order to achieve the above object, the present invention provides a method for passing a transfer material through a transfer site formed by an image carrier and a transfer means disposed close to the image carrier. In the image forming apparatus that forms a toner image on the transfer material, at least one piece of toner is provided at the leading end of the transfer material in the transfer material conveyance path upstream of the transfer site when viewed in the traveling direction of the transfer material. It is characterized in that it is provided with a bending means for forming folds.

With this configuration, it is possible to reliably separate the transfer material even when curling of the transfer material is certain to occur, especially in the case of double-sided copying, thereby avoiding the occurrence of jams. and stable separation can be obtained.

(Description of Embodiments) FIG. 1 shows an embodiment in which the present invention is applied to a multiplex/double-sided type image forming apparatus as described above.

The basic configuration of the device shown in FIG. 7 is the same as the device shown in FIG. This shows the configuration near the part where the
It is assumed that a transfer material that has undergone a fixing process and has curled is stored.

Reference numeral M116 in FIG. 1 is a motor for operating the roller pair 116, which is controlled by the control circuit 60, and reference numeral 61 is a keyboard for instructing the control circuit 60 on the number of copies, copy mode, copy start, etc.

A sensor 116D that detects the presence of the transfer material is disposed on the conveyance guide 55.56 on the downstream side of the paper refeeding roller pair 116 when viewed in the traveling direction of the transfer material. When the position is reached, a pressing device 210, which will be described later, is activated.

Next, according to FIGS. 2 to 4, the pressing device 21
0 will be explained.

As shown in FIG. 2, the device 210 includes a solenoid 64
and a pressing member 21OA that appears and retracts within the carrying path formed by the guides 55 and 56.

The receiving member 210B is arranged opposite to this and is made of a material with appropriate flexibility such as sponge or felt. Projections 2] and Oa (three are shown in the figure) are formed.

When the sensor 116D detects that the transfer material has arrived at a predetermined position, the MPU energizes the solenoid 64 for a predetermined period of time, and the pressing member 210A
The protrusion 210a advances to the conveying path, and further protrudes to bite into the receiving member 210B as shown in the third figure, and a mark 3'a is attached to the leading end portion of the transfer material 3' passing therethrough.
A nearly triangular fold as shown in is formed.

Thereafter, the pressing member 210A is retracted out of the conveyance path by the deenergization of the solenoid, and the transfer material is conveyed to the transfer site via the registration roller pair 9.

In this case, as shown in FIG. 4, a recess 9a is formed in a portion of one of the pair of registration rollers corresponding to the fold 3'a so as not to crush the fold. shall be kept.

When the transfer material arrives at the transfer site with the fold 3°a present, as shown in FIG. Separation is also reliable, and subsequent parts of the transfer material are also easily separated, so it is possible to prevent separation defects and separation claw marks from occurring.

Note that there is no problem because the fold line 3'a formed in the transfer material is dipped by the pressure that the transfer material receives when it finally passes through the fixing site.

Next, the above-mentioned series of operations will be briefly explained with reference to the flowchart shown in FIG.

When a copy start is instructed after duplex or multiple copy mode is set using the keyboard 61, the transfer material on which the first image formation was performed is stored in the re-feeding section A and used for the second copy until a predetermined number of copies have been completed. Waiting for copying.

When the second copy start is instructed (step 1)
The motor M116 is activated and the transfer material is conveyed by the roller pair 116 (step 2).

After the transfer material advances and the time t1 elapses from when the leading edge is detected by the sensor 116D until the leading edge reaches the pressing device 210 (step 4), the motor M116 is turned off and the conveyance of the transfer material is stopped. 5) At the same time, the solenoid 64 is energized, and the aforementioned pressing device is activated to form a crease at the leading edge of the transfer material.Step 6), after that, the solenoid is deenergized and each part of the pressing device returns to its previous position. (Step 8).

Note that, in consideration of variations in photoreceptors, differences in characteristics of transfer materials, etc., it is preferable that the time t1 be set variably.

At this point, the motor M116 is activated again to drive the roller pair 116.
transports the transfer material (step 9), a second copy is performed (step 10), and after confirming that a predetermined number of copies have been completed, the operation is completed.

Although the present invention has been described above with reference to an embodiment of an apparatus that performs multiplex/double-sided copying, the present invention is not limited thereto, and curling of the transfer material may also occur in a normal type of apparatus that forms an image on only one side. Although the present invention is effective in cases where this is a problem, it is particularly effective in improving separation when applied to an apparatus in which curling occurs reliably, such as the above-described double-sided copying machine. You can expect it.

(3) As described in detail of the invention, the non-invention is that in an image forming apparatus that transports the transfer material from its storage site to the transfer site and then to the fixing site, the transfer material is removed before reaching the transfer site. By passing through the transfer site with at least one crease formed at the leading edge, the separation between the transfer material and the photoreceptor can be greatly improved, thereby avoiding jamming and ensuring stable conveyance. It has a remarkable effect on obtaining high-quality images without retransfer or separation claw marks.

[Brief explanation of drawings]

FIG. 1 is a side view of the main parts showing an embodiment in which the present invention is applied to a multiple/double-sided image forming apparatus, and FIGS. 2 and 3 are main parts showing means for forming creases on the transfer material. FIG. 4 is an end view showing the structure of the registration roller pair, FIG. 5 is a side view of the main part showing how the transfer material with folds passes through the transfer site, and FIG. 6 is the main part of the main part. FIG. 7 is a flowchart showing the operation of the invention, and a schematic side view showing the configuration of a known multiplex/double-sided copying machine. 1.2...Cassette, 3.3゛...Transfer material, 9.
...Registration roller pair, 1o...Transfer charger, 14.
... Photoreceptor, 16 ... Constant@device, 17 ... Paper ejection section,
55.56... Conveyance guide, 64... Solenoid,
116...41 paper roller pair, M116...motor,
210...pressing device. Figure 3 Figure 4 Figure 5 Figure 6 missing r7 szJ +7宕

Claims (3)

[Claims] (1) In an image forming apparatus that forms a toner image on the transfer material by passing a transfer material through a transfer site formed by an image carrier on which a toner image has been formed and a transfer means disposed close to the image carrier, An image forming apparatus comprising: a bending means for forming at least one fold in a leading end portion of a transfer material in a transfer material transport path upstream of the transfer material in the traveling direction of the transfer material. (2) A patent claim in which a folding means for forming folds on a transfer material is disposed downstream of a paper refeeding section of an image forming apparatus that performs image forming operations on one transfer material two or more times. The image forming apparatus according to scope 1. (3) The bending means for forming a crease in the transfer material is arranged on a flexible member disposed on one side of the transfer material conveyance path and at a portion opposite to the flexible member, and a retreat position that opens the conveyance path. 3. The image forming apparatus according to claim 1, further comprising a pressing member that is selectively displaced between the pressing member and the position where the flexible member comes into contact with the flexible member.