JPH09127800A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of performing excellent image forming irrespective of a tab paper. SOLUTION: On the front side corresponding to the paper feeding direction of the paper feeding tray 27 of the paper feeder of the device, a side board 24 is located, and on the rear side a back fence 26 is located. Then, an access roller 23 is held in contact with the upper most transfer paper, the transfer paper called out by the access roller 23 is separated for a sheet by a feed roller 21 and a reverse roller 22, and sent to the resist rollers side. At this time, the back fence 26 is allowed to fill function so as to prevent the transfer paper from being sent in the direction opposite to the paper feeding direction, then a part 26a formed in a curved surface shape whose curvature is smaller than the curvature of a photoreceptor drum is formed on the top end part of the back fence 26, the tub part 26a is deformed by this part 26a, and the curvature is imparted therefor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus for forming an image on tab paper.

[0002]

2. Description of the Related Art A tab sheet is a sheet in which a section for entering a heading or a title is provided so as to project in the longitudinal direction of the sheet.
Generally, one set consists of 5 to 6 sheets. Since the tab sheet contains the sheets classified between the tab sheet and the tab sheet, it is generally thick paper, and the plain paper is 50 kg to 80 K.
While the thickness is g, the thickness is equivalent to 110 kg to 180 kg. Therefore, when the corona transfer is used because the paper is stiff, it is difficult to follow the curvature of the drum when the photoconductor has a drum shape, which makes it difficult to contact the photoconductor, and in particular, the rear end portion is difficult to transfer. . With respect to the shape of the tab sheet, the tab portion inevitably becomes the rear end in consideration of transportability, so that image formation particularly on the tab portion becomes a problem. In addition, since the transfer area of the tab portion is small (especially, the dimension in the carrying direction is small), the transferability is worse than that of a regular-shaped sheet having the same thickness.

Therefore, although it is not a tab sheet, a transferability of the trailing edge of the sheet is taken into consideration, for example, Japanese Patent Application No. 62-569.
It is known from those described in Japanese Patent Publication No. 77 or Japanese Patent Application Laid-Open No. 2-136269.

In the former known technique, the output of transfer is increased only at the trailing end of the transfer paper, and in the latter known technique, the transfer guide member is moved only at the trailing end of the transfer paper and the trailing end is a photosensitive member. It is configured to be pressed against.

[0005]

However, the former prior art has some effects in the case of transfer paper having a weak stiffness, but not in the case of thick paper having a stiffness. Further, in the latter prior art, when the trailing edge of the transfer paper leaves the guide member, the trailing edge becomes free, and therefore, in the case of thick thick paper, it tends to bounce and transfer failure often occurs.

The present invention has been made in view of the above problems of the prior art, and an object thereof is to provide an image forming apparatus capable of forming an excellent image even with a tab sheet.

[0007]

In order to solve the above problems, a first means is an image forming apparatus using a photoconductor drum capable of forming an image on a tab portion of a sheet having a tab at an end thereof. The apparatus further comprises means for deforming the sheet so as to follow the curvature of the photosensitive drum at a position where an image is transferred from the photosensitive drum to the sheet.

In the second means, the means for deforming the paper in the first means is provided at the portion where the tab paper of the paper feeding means on which the transfer paper to be fed to the photoconductor is stacked comes into contact. Is characterized by.

A third means is characterized in that a portion of the second means which comes into contact with the tab sheet is formed in a curved surface shape having a curvature smaller than that of the photosensitive drum.

The fourth means is characterized in that the portion of the second or third means with which the tab paper is brought into contact is provided on a back fence which regulates the rear end of the transfer paper laminated on the paper feeding means. And

The fifth means is characterized by including means for changing the position of the back fence in the fourth means and selecting whether or not to deform the tab sheet.

The sixth means is characterized in that it is provided with means for detecting whether or not the back fence in the fifth means is located at a position for deforming the tab sheet.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of an image forming apparatus according to the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic configuration diagram of an image forming apparatus as an embodiment of the present invention. In the figure, on the outer periphery of the photoreceptor 1, a charging / discharging device 2, an eraser 3, a developing device 4, a pre-transfer charge eliminating lamp 5, a transfer / separating / discharging device 6, facing the outer peripheral surface (photosensitive layer) of the photoreceptor 1, Separation claw 8 and cleaning device 9
The static elimination lamp 10 is arranged counterclockwise in the figure. Reference numeral 11 is a charging / discharging device 2 and an eraser 3.
And writing light from an optical system (not shown) that is irradiated between and.

The transfer sheet sent from the sheet feeding device described later is sent out along the guide plate 15 to the transfer position in synchronization with the image on the photoconductor 1 by the pair of registration rollers 3 and 4. Then, after the image is transferred onto the transfer paper at the position of the transfer / separation discharger 6, the image is transferred by the transfer belt 7 and sent to a fixing device (not shown). At the transfer section, the transfer paper is brought into close contact with the photoconductor 1 due to the transfer electric field, and the toner image is transferred onto the transfer paper. If so, the tab portion at the rear end becomes flat, and it is difficult to make close contact with the photoconductor 1. If the close contact state is not maintained, transfer failure will occur. This naturally becomes worse as the diameter of the photoreceptor 1 becomes smaller.

FIG. 2 is a schematic configuration diagram showing the structure of the sheet feeding section according to this embodiment. The side plate 24 is located on the front side and the back fence 27 is located on the rear side with respect to the sheet feeding direction of the sheet feeding tray 27. ing. Then, the calling roller 23 comes into contact with the uppermost transfer sheet, and the transfer sheets called by the calling roller 23 are separated one by one by the feed roller 21 and the reverse roller 22 and sent to the registration rollers 13 and 14 side. The so-called FRR paper feeding method is adopted. The back fence 26 functions to prevent the transfer paper from being sent out in the direction opposite to the paper feeding direction.

FIG. 3 is a perspective view of the sheet feeding section, which shows the tray 27.
And the calling roller 23 is lifted by the transfer paper on the tray 27 to a predetermined position, the tray 27 is lifted by the detection output of the upper limit detection sensor 28 and the rotation of the tray motor 29 shown in FIG. 4 is stopped. Paper is fed by the calling roller 23. When the transfer paper is reduced due to the paper feeding, the calling roller 23 is also lowered, and when the transfer roller is lowered to a preset position, the filler of the upper limit detection sensor 28 is removed and the tray motor 29 is started to rotate again. It is designed to hold the paper position. In the figure, 30 is a paper feed clutch, 31 is a paper feed detection sensor, and 32 is a pickup solenoid.

FIG. 4 is a view showing a tray lifting mechanism. The tray motor 29 is arranged in the lower portion, and the tray motor 2 is provided.
The drive transmission mechanism including the pulley 33 and the wire 34 causes the tray 27 to move up and down. The reference numeral 34 indicates the rotation of the tray motor 29 and the disk 35.
Is a sensor for detecting the remaining amount of the transfer paper which is detected by.

FIG. 5 is a perspective view showing the paper feed tray unit. In addition to the paper feed tray of FIG. 2 described above, side fences 36 and 37 that move in parallel with the conveying direction in the width direction are shown. . The positions of the side fences 36 and 37 are detected by a sensor (not shown), and the size of the transfer paper can be detected.

FIG. 6 is a sectional view showing a state in which tab sheets are set in the sheet feeding tray unit. As can be seen from FIG. 5, the upper portion of the back fence 26 is provided with a curvature and is formed in a curved surface curved in the paper transport direction.
Therefore, the tab sheet 50 at the upper position is held in a deformed state along the curvature of the back fence 26. That is, as can be seen from the perspective view showing the state in which the tab sheets 50 in FIG. 7 are overlapped, 5 to 6 kinds of tabs 51 having different positions are overlapped, and therefore the tab 51 portion is vertically moved when it is overlapped. There is a gap in. As a result, only the portion of the tab 51 can be deformed. It should be noted that the dimension xa of the portion 26a having the curvature formed as shown in FIG. 6 is shorter than the length xb of the tab 51 as shown in FIG. 7, and the radius of curvature R of the portion 26a is smaller than the radius of the photoconductor 1. Is also small. this is,
This is because even if the tab 51 is deformed on the paper feed tray 27, a force is applied in the direction of returning the deformation while the tab 51 is being conveyed to the transfer position, and that is foreseeable. With this configuration,
As the tab paper 50 is conveyed, the paper feed tray 27 rises, and is gradually deformed in each case, and a predetermined deformation amount is obtained at the uppermost position, and the tab paper 50 is sequentially fed.

FIG. 8 is a perspective view showing details of the back fence. As can be seen from this figure, the back fence 26 is attached to the shaft members 38 and 39. As shown in the shaft member enlarged view of FIG. 9, the shaft member 38 has constrictions 4 at two positions.
0, 41 are provided, and the back fence 26 is formed by cutting out a part thereof to form projecting pieces 42, 43.
Is wound around the shaft member 38 and attached. As shown in FIG. 9, the protrusions 42 and 43 have the constrictions 40 and 4 respectively.
A protrusion 44 that elastically engages with the shaft 1 is formed so that the relative positions of the shaft member 38 and the back fence 26 are maintained. Therefore, when the back fence 26 is pulled upward from the position of FIG. 9, the protrusion 44 disengages from the lower neck 40 and elastically engages the upper neck 41.
Therefore, if the operator operates the back fence 26,
With a click feeling, it is possible to recognize whether or not the vehicle is located at a predetermined position.

When the back fence 26 is in the lower position, the sensor (light transmission type sensor) 45 is turned off, and when the back fence 26 is moved upward, the sensor 45 is removed from the position, so that the position of the back fence 26 can be electrically detected. It has become.

In the case of a normal transfer sheet other than the tab sheet 50, when the back fence 26 is lowered, it is caught on the curvature forming portion 26a, so that the paper feed tray 27 is raised according to the detected position of the back fence 26. It is possible to control such as not to perform. It can also be used to detect whether the paper stored in the paper feed tray 27 is the tab paper 50 or a normal transfer paper based on the operation state of the operator.

In this embodiment, the operator, especially the user himself / herself moves the back fence 26, but naturally, the back fence 2 is driven by the motor.
The ascending / descending operation of 6 can also be performed. Needless to say, if a tray dedicated to the tab sheet 50 is provided, the mechanism for raising and lowering the back fence 26 is unnecessary.

In this embodiment, the CPU executes the paper feed control, the detection of the back fence position and the like according to the program set in the ROM of the control circuit (not shown).

[0026]

As is apparent from the above description, the present invention has the following effects.

That is, the invention according to claim 1 further comprises means for deforming the tab portion of the sheet so as to follow the curvature of the photosensitive drum at the position where the image is transferred from the photosensitive drum to the sheet. For example, when an image is transferred on the surface of the photoconductor, the tab part is deformed to follow the curvature of the photoconductor drum, so the tab part does not separate from the photoconductor and the tab part does not separate. Also, good image formation can be performed.

According to the invention of claim 2, wherein the means for deforming the sheet is provided at a portion of the sheet feeding means on which the transfer sheet to be fed to the photoconductor is stacked, the tab sheet comes into contact with the sheet. Since the sheet can be deformed on the side of the sheet feeding means for performing the operation, the tab portion can be surely deformed.

According to the invention as set forth in claim 3, wherein the portion where the tab sheet comes into contact is formed in a curved surface having a curvature smaller than that of the photosensitive drum. Since it can be deformed into a curvature along the curvature, a good transferred image can be obtained.

According to the invention described in claim 4, wherein the back tab is provided with a portion where the tab paper for contacting is provided, a good transferred image can be obtained without impairing the setting quality of the transfer paper.

A means for changing the position of the back fence and selecting whether or not to deform the tab sheet is provided.
According to the invention described above, since it is possible to release the setting of the member that deforms the tab portion, it is possible to use one tray for both the tab paper and the plain paper, and obtain a good transfer image without impairing the setting property.

According to the invention of claim 6, further comprising means for detecting whether or not the back fence is located at a position for deforming the tab sheet, the tab sheet or the plain sheet can be recognized. Therefore, it is not necessary for the operator to input the distinction between the two by using the operation unit, which can prevent the occurrence of malfunction.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an image forming unit of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing a paper feed system including a paper feed tray according to an embodiment of the present invention.

FIG. 3 is a perspective view of an essential part showing a mechanism near a calling roller of the paper feeding system of FIG.

FIG. 4 is a schematic configuration diagram of an ascending / descending mechanism of the paper feed tray of FIG.

5 is a perspective view showing a state of a back fence and a side guard in the paper feeding system of FIG.

FIG. 6 is a cross-sectional view showing a deformation imparting mechanism by the back fence of FIGS. 2 and 5.

FIG. 7 is a perspective view showing a state of a tab portion of tab paper.

FIG. 8 is a perspective view showing a mounting mechanism of a back fence.

9 is a side view, partly in section, showing the position selection mechanism of the back fence of FIG.

[Explanation of symbols]

 26 Back Fence 26a Curved Part 27 Tray 38,39 Shaft Member 40,41 Constriction 42,43 Projection Piece 50 Tab Paper 51 Tab Part

Claims (6)

[Claims] 1. An image forming apparatus using a photoconductor drum capable of forming an image on a tab portion of a sheet having a tab at an end thereof, wherein the photoconductor is located at a position where an image is transferred from the photoconductor drum to the sheet. An image forming apparatus comprising means for deforming a tab portion of the sheet so as to follow the curvature of the body drum. 2. The means for deforming the sheet is provided in a portion where the tab sheet of the sheet feeding means on which the transfer sheet to be fed to the photoconductor is stacked is brought into contact.
The image forming apparatus as described in the above. 3. The image forming apparatus according to claim 2, wherein the portion where the tab sheet comes into contact is formed in a curved surface shape having a curvature smaller than that of the photosensitive drum. 4. The image forming apparatus according to claim 2, wherein a portion where the tab sheet contacts is provided on a back fence that regulates a rear end of the transfer sheet laminated on the sheet feeding unit. apparatus. 5. The image forming apparatus according to claim 4, further comprising means for changing the position of the back fence and selecting whether or not to deform the tab sheet. 6. The image forming apparatus according to claim 5, further comprising means for detecting whether or not the back fence is positioned to deform the tab sheet.