JPH04141468A - Image forming apparatus - Google Patents

Abstract

PURPOSE:To make superposition or double side copy possible by providing an extremely simple apparatus by moving upwardly discharged transfer paper toward the double-side unit provided on the side opposite to an image forming part from above to below and feeding the same on the side opposite to a paper feed unit to form an image. CONSTITUTION:When a superposition copy mode is selected, a guide piece 60 is rotated in a counterclockwise direction to be held and a transfer material having an image fixed thereto is fed to a double-side unit 70 through a paper discharge path B and again receives the transfer of the next image in a superposed state through a timing roller 17. The guide piece 60 is again rotated corresponding to a paper discharge condition on the basis of the signal of a sensor S1 detecting the passage of the rear end of the transfer material to discharge the transfer material to a predetermined tray. When a double-side copy mode is selected, the guide piece 60 is rotated in the clockwise direction to be held and the transfer material having an image fixed to the single surface thereof is fed in a paper discharge path C and the guide piece 60 is rotated in the counterclockwise direction on the basis of the signal of a sensor S2 detecting the passage of the rear end of the transfer material and, at the same time, a paper discharge roller 19 is reversely rotated for a definite time to feed the transfer material in the double-side unit 70 through the paper discharge path B.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrophotographic image forming apparatus that forms an image on a transfer material such as a copying machine or a printer using a laser method.

[Background of the invention]

In laser-type image forming apparatuses that have a separate document image reading system unit, there is no document table in the main body of the device, so the upper part is used as a paper ejection tray to eject and stack the transfer material after image transfer. Use it for.

There is no need to provide a discharge tray that protrudes outside the fruiting device, and therefore, the space around the device can be effectively utilized for copying and maintenance work.

[Problem that the invention seeks to solve]

However, in the above-mentioned device, it is necessary to flip the transfer material inside the device, and on the other hand, since the image itself is transferred to the front surface of the transfer material, that is, the upper surface, the transfer material is placed with the image side facing downward. is discharged. Therefore, it has the disadvantage that it is inconvenient to check the finished state of the image during copying.

Further, such devices are generally limited to those that copy only on one side of a transfer material, and no device has yet been provided that can perform various copying processes such as overlapping on the same side and duplex copying.

As a result of solving and improving this problem, the present invention provides an image forming apparatus that can perform overlapping and double-sided copying by installing an extremely simple device, and can also eject images with the image surface facing upward. This is the purpose.

[Means to solve the problem]

The above purpose is to provide an image forming apparatus in which a paper feeding unit is provided at the bottom and the transfer paper on which an image has been formed is ejected from the bottom to the top. This is achieved by an image forming apparatus characterized in that the image is formed by moving the paper from above to below toward the paper feed unit and then feeding the paper from the side opposite to the paper feeding unit.

〔Example〕

An embodiment of the color image forming apparatus of the present invention is shown in FIGS. 1 to 3.

In FIG. 1, ■ is a flexible photoreceptor belt that is a belt-shaped photoreceptor, and the photoreceptor belt 1 is connected to rotating rollers 2 and 3.
The rollers 2 are conveyed clockwise by the drive of the rotating rollers 2.

Reference numeral 4 denotes a support member or guide member fixed to the main body of the apparatus so as to be inscribed in the photoreceptor belt l, and the photoreceptor belt l is brought into a tensioned state by the outward biasing action of the rotary roller 3. The inner peripheral surface of the guide member 4
Let it rub.

Therefore, the photoreceptors on the outer circumferential surface of the photoreceptor belt 1 are always maintained at a constant position relative to the surface of the guide member 4 even during conveyance, making it possible to form a stable image forming surface.

Reference numeral 6 denotes a scorotron charger as a charging means, 7 a laser writing system unit as an image exposure means, 8 to 11 a plurality of developing devices each containing a developer of a specific color, and each of these image forming means is provided with a guide. It is disposed opposite to the peripheral edge of the photoreceptor belt 1 with the member 4 facing back.

In addition to the optical system shown in the drawings, the laser writing system unit 7 may also include an optical system that integrates a light emitting section and a convergent light transmission body.

Each of the developing units 8.9.10.11 accommodates, for example, yellow magenta, cyan, and black developers, respectively, and includes developing sleeves that maintain a predetermined gap from the photosensitive belt 1. It has the function of making the upper latent image visible using a non-contact development method. Unlike contact development, this non-contact development has the advantage of not interfering with the movement of the photoreceptor belt.

12 is a transfer device, 12 is a static elimination bar, 13 is a cleaning device, and a blade 13A of the cleaning device 13].
The toner conveying roller 13B is connected to the photoreceptor belt 1 during image formation.
The photoreceptor belt 1 is kept in a position apart from the surface of the photoreceptor belt 1, and is pressed against the surface of the photoreceptor belt 1 as shown in the figure only during cleaning after image transfer.

The process of forming a color image by the color image forming apparatus is performed as follows.

First, the formation of a multicolor image according to this embodiment is performed according to the following image forming system. That is, data obtained by a color image data input section in which an image sensor scans an original image is processed by an image data processing section to create image data, which is stored in a star image memory. The image memory is then taken out during recording and input into the main body of the color image forming apparatus shown in the embodiment of FIG. 1, which is a recording section.

That is, when input to the laser writing system unit 7 outputted from an image reading device separate from the above device, the laser beam generated by a semiconductor laser (not shown) is transmitted to the drive motor in the laser writing system unit 7. It is rotated and scanned by the polygon mirror 7B rotated by 7A, and f
The light path is bent by the mirrors 7D and 7E via the θ lens 7C, and is projected onto the circumferential surface of the photoreceptor belt l, which has been charged in advance by the charger 6, which is a charging means, to form a bright line.

On the other hand, when scanning is started, the beam is detected by the index sensor, modulation of the beam by the first color signal is started, and the modulated beam scans over the circumferential surface of the photoreceptor bell)l. Therefore, a latent image corresponding to the first color is formed on the circumferential surface of the photoreceptor belt 1 by main scanning by the laser beam and sub-scanning by the conveyance of the photoreceptor belt 1. This latent image is developed by a developing device 8 loaded with yellow (Y) toner (developing medium) of the developing means, and a toner image is formed on the drum surface. The obtained toner image passes under a cleaning device 13, which is a cleaning means, which is separated from the surface of the photoreceptor belt 1 while being held on the drum surface, and enters the next copy cycle.

That is, the photoreceptor bell) 1 is charged again by the charger 6, and then the second color signal output from the signal processing section is input to the writing system unit 7, and in the case of the first color signal described above. Writing is performed on the drum surface in the same manner as described above, and a latent image is formed. The latent image is developed by a developer 9 loaded with magenta (M) toner as a second color.

This magenta (M) toner image is formed in the presence of the previously formed yellow (Y) toner image.

IO is a developing device having cyan (C) toner, which forms a cyan (C) toner image on the drum surface based on a control signal generated by a signal processing section.

Furthermore, 11 is a developing device having black toner, and forms a black toner image superimposed on the belt surface by the same process. These developing units 8.9°10 and 11
A direct current or even alternating current bias is applied to each sleeve, and jumping development is performed using a two-component developer, which is a developing means, and development is performed without contact on the photoreceptor belt 1 whose base is grounded. It has become. Incidentally, as the development, non-contact development using a -component developer can also be used.

The color toner image thus formed on the circumferential surface of the photoreceptor belt 1 is transferred to a transfer material fed from the paper feed cassette 14 via the paper feed guide 15 at the transfer section.

That is, the top layer of the transfer material stored in the paper feed cassette 14 is carried out by the rotation of the paper feed roller 16, and transferred to the transfer device 12 via the timing roller 17 in synchronization with the image formation on the photoreceptor belt 1. supplied to.

The transfer material that has undergone image transfer and static electricity removal is transferred to the rotating roller 2.
The image is reliably separated from the photoreceptor belt 1, which suddenly changes direction along the direction of the photoreceptor belt 1, and moves upward via the suction type conveyor belt 17A, and after the image is fused by the fixing roller 18, it is delivered to the outside of the apparatus via the paper ejection path described later. is discharged.

On the other hand, the photoreceptor belt 1 that has completed the transfer to the transfer material continues to be conveyed to the blade 13A and the toner conveying roller 13B.
The remaining toner was removed in the cleaning device 13 which was brought into pressure contact with the blade 13A, and after the cleaning was finished, the blade 13A was separated again, and a little later, the toner conveying roller 13B leveled the toner accumulated on the tip of the blade 13A. Afterwards, the toner conveying roller 13B is separated and a new image forming process begins.

The photoreceptor belt 11, the charger 6, each developing device, and the cleaning device 13 are integrated into an independent process cartridge 30, and then placed on a pedestal 50 that slides on a guide rail 40 inside the device. be accommodated in.

In the image forming apparatus of the present invention, there are three paper discharge paths for the transfer material.
The guide piece 60 is rotatably provided at the branching point.

A plurality of the guide pieces 60 are mounted on a rotatable rotating shaft 61 in the same phase and at appropriate intervals,
It is rotated and held at a predetermined angle by the control section in accordance with the copy mode selection.

FIG. 2 shows each rotational position of the guide piece 60 and the discharge path of the transfer material formed thereby.

In other words, as shown in FIG. 3, when a sheet is ejected with the image side facing downward in single-sided copying, there is no need to set a copy mode, and the guide piece 60 is always kept at the angle shown in FIG. 2(A). The transfer material that is being held and on which the image has been fixed passes through the paper ejection path A and is ejected via the paper ejection roller 19 onto a tray formed on the upper lid 20 .

Further, when a mode is selected in which the paper is ejected with the image surface facing upward, the guide piece 60 is rotated clockwise from the angle shown in FIG. 2(A) to the angle shown in FIG. 2(C). The transfer material passes through the paper discharge path C and is then rotated and held by the paper discharge roller 1.
．． It is discharged onto tray 20A via 9A.

Furthermore, a paper feed guide 71 and conveyance rollers 72A, 72B
By adding the duplex unit I/70 containing the 72C, it becomes possible to perform overlapping copying on one side of the transfer material and double-sided copying. In this case, paper feeding from the paper feeding cassette 14 is temporarily interrupted.

When the overlapping copy mode is selected, the guide piece 60 is rotated counterclockwise from the angle shown in FIG. 2(A) and rotated and held at the angle shown in FIG. 2(B), The transfer material on which the image has been fixed is conveyed to the duplex unit 70 via the paper discharge path B, and the next image is superimposed and transferred via the timing roller 17 again.

Based on the signal from the sensor Sl that detects the passage of the trailing edge of the transfer material, the guide piece 60 moves from the angle shown in FIG. 2(B) again to the direction shown in FIG. 2(A) or FIG. 2(C) depending on the paper discharge conditions. The transfer material is rotated at an angle shown in , and is discharged onto a predetermined tray.

On the other hand, when the double-sided copy mode is selected, the guide piece 60 is rotated clockwise from the angle shown in FIG. 2(A), rotated and held at the angle shown in FIG. The transfer material with the image fixed thereon is once sent to the paper discharge path C.

The guide piece 60 rotates counterclockwise based on the signal from center → t-32 that detects the passage of the rear end of the transfer material, and the guide piece 60 rotates in the counterclockwise direction.
), and at the same time the paper ejection roller 19A rotates in reverse for a certain period of time to send the transfer material through the paper ejection path B to the duplex unit 70.
send to.

Therefore, the transfer material is turned upside down when the timing roller 1
7, and the next image is transferred to the back side.

Based on the signal from the sensor Sl that detects the passage of the trailing edge of the transfer material and depending on the Ur paper condition, the guide piece 60 either stands still at the angle shown in FIG.
It rotates at the angle shown in C) and discharges the transfer material onto a predetermined l-lay.

The angle of the guide piece 60 automatically returns to the angle shown in FIG. 2(A) when each copy mode is reset, and is set to the normal paper ejection condition for single-sided copying.

FIG. 3 shows the control state of the position of the guide piece corresponding to each copy mode.

Note that this duplex unit 70 is detachably installed in the image forming apparatus, and when it is not installed, overlay copying and duplex copy mode are prohibited, and the duplex unit 70 is
The position of the guide piece (FIG. 2(B)) that conveys the transfer material to the position 0 is never set.

〔Effect of the invention〕

The present invention makes it possible to change the transfer material discharge conditions by installing an extremely simple device, and also realizes superimposition of images and double-sided copying.As a result, various copies can be obtained at low cost. As a result, a highly practical image forming apparatus can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional configuration diagram of an image forming apparatus of the present invention, FIG. 2 is a diagram of its main parts, and FIG. 3 is an explanatory diagram showing the contents of a copy mode by the apparatus. l...Photosensitive belt 6...Charger 7...Laser writing system unit 8 9 10.11...Developer 12...Transfer device 12
A... Static elimination lever 14... Paper feed cassette 17... Timing port 18... Fixing roller 2OA... Tray 70... Duplex units A, B, C... Paper ejection path 13...・Cleaning device 15.71...Paper feed guide 19.19A...Paper discharge port 60...Guide piece/Sensor

Claims (1)

[Claims] In an image forming apparatus in which a paper feeding unit is provided at the bottom and the transfer paper on which an image has been formed is ejected from the bottom to the top, the transfer paper ejected upward is placed on the side opposite to the image forming section. An image forming apparatus characterized in that an image is formed by moving a sheet from above toward a duplex unit and then feeding the sheet from a side opposite to a sheet feeding unit.