JPS61124975A - Image forming device - Google Patents

Abstract

PURPOSE:To align a top and a reverse image vertically during both-surface image formation by branching a paper which have an image formed on one surface from a re-supply conveyance path which supplies the paper to an image formation part, inverting the conveyance- directional right and left sides of the paper and then turning over the paper in the middle of the conveyance, and returning it to the re-supply conveyance path. CONSTITUTION:The paper P is conveyed through a main conveyance path 27 and a developer image is transferred from a photosensitive drum 5 to the surface at a transfer part 29 and then fixed by a fixing device 30. Then, the paper is passed between paper discharge rollers 25, branched to a U-turn path 40 by a gate 37, and further branched to a branch line 43 by a branch gate 39, so that the paper is stacked at a stacking part 44 through a carrying-out roller 53. Then, the paper is taken out by a takeout roller 45 at right angles to the paper conveyance direction of the transfer part 29 and carried in the U-turn path 46, and then stacked at a stacking part 41 through a carrying-out roller 51. At this time, the paper has the right and left sides inverted as compared with the stacking state at the stacking part 44 and is turned over, but the front-rear relation of the form P is unchanged. Then, the papers are taken out by a takeout roller 42 from the uppermost paper in order, carried in a U-turn part 31 through a carrying-in roller 49, and returned to the upstream side of the main conveyance path 27, so that the paper is supplied to the transfer part again.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an image forming apparatus that can automatically perform multiple image formation and double-sided image formation.

[Technical background of the invention and its problems]

As an image forming apparatus that can automatically perform multiple image formation and double-sided image formation, an apparatus configured as follows has been proposed. That is, when performing multiple image formation, after an image is transferred from an image carrier to one side of a sheet of paper fed from a sheet feeding section at a transfer section, this sheet of paper is transferred again to the above-mentioned surface via an annular conveyance path. Supplied to the transfer section. Then, in this transfer section, the image is transferred from the image carrier so as to be superimposed on the surface of the paper onto which the image has been transferred, and then the paper is discharged. Further, when double-sided image formation is performed, an image is transferred from an image carrier to one side of a sheet fed from a sheet feeding section in a transfer section, and then this sheet is carried into the annular conveyance path.

Then, it branches on the way of this annular conveyance path and is carried into a direction changing section. Then, the paper carried into this direction changing section is carried out from the rear end side in the carrying direction, that is, it is switched back to join the above-mentioned annular conveyance path, and is again supplied to the above-mentioned transfer section via this annular conveyance path. . After the image is transferred from the image carrier to the other side of the paper in this transfer section,
I am trying to eject the paper.

However, the above configuration requires complicated mechanisms such as a paper position detection means and a conveyance direction reversing means for switching back the paper during double-sided image formation, and a space for the same.

In addition, in the case of image formation in which the vertical direction of the transferred image matches the paper feeding direction in the transfer section, when forming double-sided images, the vertical direction of the image is reversed on the front and back sides, as shown in Figure 6. become.

[Purpose of the invention]

The present invention has been made based on the above circumstances, and aims to simplify the configuration and save space, and furthermore, the vertical direction of the image to be formed coincides with the paper feeding direction in the image forming section. For image formation such as
An object of the present invention is to provide an image forming apparatus that can align images on the front and back sides in the vertical direction during double-sided image formation.

[Summary of the invention]

In order to achieve the above object, the present invention provides an image forming section in the middle of a main conveyance path that conveys paper fed from a paper feed section to a paper discharge section, and forms an image on one side of the paper. In the image forming apparatus, there is a re-supply conveyance path which supplies the paper with an image formed on one side by the image forming section to the image forming section again, and a re-supply conveyance path which branches off from this re-supply conveyance path and extends in the conveyance direction during conveyance. On the other hand, the present invention is characterized by comprising a front-back converting path which converts the front and back sides of the sheet by reversing the right and left sides of the sheet and joins the re-supply conveyance path.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 to 5.

1 and 2 show an image forming apparatus according to the present invention, and numeral 1 in these figures indicates a main body. This main body 1
The image forming apparatus is composed of a main unit 2 which is normally used and an additional unit 3 which is added to the main unit 2 during multiple image formation and double-sided image formation, and is separable.

The main unit 2 can be used alone and is shown in detail in FIGS. 3 and 4.

That is, a document mounting table 4 is provided at the upper part of the main unit 2, and a photoreceptor drum 5 which rotates in a predetermined direction is pivotally supported approximately at the center of the main unit 2. An exposure optical system 6 is provided between the photosensitive drum 5 and the document mounting table 4.
is provided, which includes a scanning lamp 7 and a scanning mirror 8
scans the original on the original platen 4 at a predetermined speed, and the guide mirrors 9 and 10 move at a speed 172 times the speed of the scanning mirror 8 to keep the optical path length constant. It reciprocates synchronously with the rotation of 5. The document on the document table 4 is illuminated by a scanning lamp 7, and the reflected light is guided onto the photosensitive drum 5 by mirrors 8, 9, 10, 11 and a lens 12 to form an image of the document. ing.

Also, in order from this image forming position along the rotational direction of the photoreceptor drum 5, a developing device 13, a transfer charger 14, a peeling charger 15, a cleaning device 16, and a static elimination lamp 17 are provided.
, and a charger 18 are provided.

Further, at the bottom of the main unit 2, there is a paper feed section 19 on the negative side.
A paper discharge section 20 is provided on the other side. and,
The paper feed section 19 is composed of upper and lower paper feed cassettes 21.22 that accommodate paper p of different sizes, and paper feed rollers 23.24 that feed the paper p independently from these cassettes 21.22. The paper ejection section 2o is composed of a paper ejection roller 25 and a main unit paper ejection tray 26.

Roughly speaking, a main conveyance path 27 is provided at the bottom of the main unit 2 for conveying the paper p substantially horizontally, and this conveys the paper p fed from the paper feed section 19 through registration rollers 28,
The sheet is conveyed to a paper discharge section 20 via a transfer section (image forming section) 29 between the photosensitive drum 5, transfer charger 14, and peeling charger 15, and a fixing device 30 in this order.

Therefore, when using the main unit 2 alone, first,
After the photosensitive drum 5 is charged to a predetermined potential by corona discharge by the charger 18, it is exposed to light by the exposure optical system 6, thereby forming an electrostatic latent image corresponding to the original. This electrostatic latent image is developed by applying a developer by the developing device 13, thereby forming a developer image. This developer image is transferred by the transfer charger 14 onto one side of the paper p in the transfer section 29, and the paper p to which this developer image has been transferred is separated from the photoreceptor drum 5 by the peeling charger 15, and then transferred to the fixing device 30. After the developer image is fixed, the paper is discharged to the main unit paper discharge tray 26. On the other hand, the developer remaining on the photoreceptor drum 5 without being transferred onto the copy paper p is removed by a cleaning device 16, and the surface of the photoreceptor drum 5 from which the residual developer has been removed is neutralized by a charge removal lamp 17. and enters the next copying process.

Incidentally, at the bottom inside the main unit 2, a part of conveyance guides 32, 32 forming a second U-turn path 31, which will be described later, is arranged.

As shown in FIGS. 1 and 2, the additional unit 3 is removably connected to the lower side of the main unit 2, and includes an additional unit paper ejection tray 33 and a paper ejection roller 2.
5, an auxiliary conveyance path 34 conveys the paper p discharged from the main unit 2 to the additional unit paper discharge tray 33; and an auxiliary roller 35 forming a part of this auxiliary conveyance path 34;
A re-supply conveyance path 36 that conveys the paper p discharged from the main unit 2 by the paper discharge roller 25 to the transfer unit 29 again via the registration row 528, and a paper discharged from the main unit 2 by the discharge M roller 25. The first distribution that selectively distributes p to the auxiliary conveyance path 34 and the resupply conveyance path 36 is performed by the gate 3.
7, the paper p is branched from the re-supply transport path 36, and the left and right sides of the paper p are reversed with respect to the transport direction during transport.
a front/back converting path 38 for converting the front and back sides of the paper and rejoining the re-supply transport path 36; and a second sorting gate 39 for distributing the paper p from the re-supply transport path 36 to the front/reverse converting path 38. It is configured with the following.

The re-supply conveyance path 36 includes a first U-turn path 4o for making a U-turn on the sheets p sorted by the gate 37, and a first U-turn path 4o for making a U-turn on the sheets p sorted by the gate 37; a first stacking section 41 that temporarily stacks the sheets p, and a transfer section 2 that transfers the sheets p accumulated in the first stacking section 41 one by one.
9 to take out the paper in a direction parallel to the paper feeding direction.
and a second U-turn path 31 that makes a U-turn and joins the paper p taken out by the first take-out row 542 to the upstream side of the registration rollers 28 of the main conveyance path 27. There is.

The front/back conversion path 38 is provided above a branch path 43 branching from the first U-turn path 40 and the first stacking section 41, and is a first stacking path for temporarily accumulating the sheets p carried out from the branch path 43. a second stacking section 44, a second take-out roller 45 that takes out the sheets p accumulated in the second stacking section 44 one by one in a direction perpendicular to the paper feeding direction in the transfer section 29; and a third U-turn path 46 for making a U-turn on the paper p taken out by the take-out roller 45 and conveying it to the first stacking section 41 .

In addition, the first U-turn path 40 is formed by the conveyance guide 47... and the carry-out roller 548, and the second U-turn path 31 is formed by the conveyance guide 32... and the carry-in roller 49.
The third U-turn path 46 is formed by a conveyance guide 50, 50 and an unloading roller 51, and the branch path 43 is formed by a conveyance guide 47,
52 and a carry-out roller 53, respectively. Further, when the additional unit 3 is added to the main unit 2, the main unit paper discharge tray 26 is removed. In this case, the main unit discharge tray 26 and the additional unit discharge tray 33 may be shared.

However, when using the main unit 2 with the additional unit 3 and performing normal image formation on one side, the copying process is performed in the same way as when the main unit 2 is used alone, but the paper is ejected. The paper p discharged from the main unit 2 by the roller 25 is accumulated on the additional unit paper discharge tray 33 via the auxiliary conveyance path 34.

When forming a double image on one side, the paper p independently fed from the upper or lower paper feed cassettes 21 and 22 is transported to the transfer unit 29 as it is transported along the main transport path 27.
After the developer image is transferred from the photosensitive drum 5 to one side (front surface), it is fixed by the fixing device 30. Next, the first sort is distributed to a first U-turn path 40 by a gate 37 via a discharge roller 25, and is accumulated in a first accumulation section 41 via a carry-out roller 48. When performing double image formation for a plurality of copies, the above steps are repeated for the number of copies.

When a predetermined amount of paper p... is accumulated in the first stacking section 41, the first paper p is sequentially taken out by the first take-out roller 42 in a direction parallel to the paper transport direction in the transfer section 29. and is carried into the second U-turn path 31 via carrying-in rollers 49. Then, it joins the main conveyance path 27 upstream from the registration rollers 28 and is supplied to the transfer section 29 again. Here, the surface on which the developer image is transferred (surface)
The developer image is transferred from the photoreceptor drum 5, and then the paper is ejected onto the additional unit paper ejection tray 33 via the fixing device 30, the paper ejection roller 25, and the auxiliary conveyance path 34 in this order.

Note that when performing multiple image formation, the re-supply conveyance path 3
Repeat step 6 to resupply.

On the other hand, when using the main unit 2 with the additional unit 3 and performing normal image formation on both sides, first, the paper is fed independently from the upper or lower paper feed cassette 21 or 22. As the sheet p is conveyed through the main conveyance path 27, a developer image is transferred from the photosensitive drum 5 onto one side (front surface) at the transfer section 29, and then fixed at the fixing device 30.

Then, the first sorting is carried out via the paper discharge roller 25 to the gate 3.
7 to the first U-turn road 40, and then
The second distribution is distributed to a branch path 43 by a gate 39 and accumulated in a second accumulation section 44 via a carry-out roller 53. When double-sided image formation is performed for a plurality of copies, the above steps are repeated for the number of copies. Then, a predetermined amount of paper p...
When the sheets of paper p are accumulated in the second stacking section 44, they are taken out in order from the topmost sheet p by a second take-out roller 45 in a direction perpendicular to the paper conveyance direction in the transfer section 29, and then transferred to a third U-turn path 46. After being carried in, they are accumulated in the first accumulation section 41 via the carry-out rollers 51. The left and right sides of the paper p are reversed between the state where the paper p is stacked in the first stacking section 41 and the state where the paper p is stacked on the second stacking section 44, thereby converting the front and back sides of the paper p. Note that the front and back of the paper p remain unchanged.

Next, the sheets p accumulated in this first accumulation section 41...
The sheets p are taken out in order from the topmost sheet p by the first take-out roller 42 in a direction parallel to the paper conveyance direction in the two transfer sections, and are carried into the second U-turn path 31 via the carry-in roller 49. Then, the registration roller 2 of the main conveyance path 27
8 on the upstream side, and is again supplied to the transfer section 29. Here, the developer image is transferred from the photosensitive drum 5 to the other surface (back surface) on which the developer image is not transferred, and then,
The paper is ejected onto the additional unit paper ejection tray 33 via the fixing device 30, the paper ejection roller 25, and the auxiliary conveyance path 34 in this order.

Note that when double-sided multiple image formation is performed, the multiple image formation described above and the above-mentioned double-sided image formation are performed in combination.

According to the above configuration, normal single-sided image formation, normal double-sided image formation, single-sided multiple image formation, and double-sided multiple image formation can be selectively performed.

In addition, when forming a double-sided image, the front and back sides of the paper p are changed by reversing the right and left sides of the paper p with respect to the transport direction, so a paper position detecting means and a transport direction reversing means for switching back the FF1P are used. Since the complicated structure and the space thereof are unnecessary, the structure can be simplified and the space can be saved. Moreover, in the case of image formation in which the vertical direction of the transferred developer image coincides with the paper feeding direction in the transfer section 29, when forming a double-sided image, as shown in FIG. Since the directions are not reversed, the images on the front and back sides can be aligned vertically.

In the above embodiment, the paper p is temporarily stacked in the respective stacking sections 41 and 44 of the resupply conveyance path 36 and the front/back conversion path 38, but the present invention is not limited to this, and the paper p is not stacked. Then, resupplying or converting the front and back sides may be performed for each sheet.

Further, the additional unit 3 may be placed either above or below the main unit 2.

Further, the first and second accumulation sections 41.44 may be located either above or below, and the third U-turn path 46 may be located above or below the accumulation sections 41.44.
44, either the rear side or the front side.

Further, the front/back conversion path 38 is not limited to the above embodiment, and may be constructed by, for example, twisting the conveyance path by 180°.

〔Effect of the invention〕

As described above, according to the present invention, there is provided a main conveyance path that conveys the paper fed from the paper feed section to the paper discharge section, and an image formation system that forms an image on one side of the paper while it is being conveyed along the main conveyance path. a re-supply conveyance path for again supplying the paper on which an image has been formed on one side by the image forming section to the image forming section;
A front-back conversion path is provided which branches off from this re-supply conveyance path, converts the front and back sides of the paper by reversing the right and left sides of the paper with respect to the conveyance direction during conveyance, and joins the re-supply conveyance path. In the case of image formation in which the configuration is simplified and space is saved, and the vertical direction of the formed image matches the paper feeding direction in the image forming section, the vertical direction of the images on the front and back sides when forming double-sided images. It has excellent effects such as being able to align the

[Brief explanation of the drawing]

Figures 1 to 5 show one embodiment of the present invention.
The figure is a longitudinal sectional front view showing the state in which the main unit and the additional unit are connected, FIG. 2 is a side view showing the connected state with only the additional unit in section, FIG. Similarly, FIG. 5 is a perspective view showing the inside of the main unit, FIG. 5 is an explanatory diagram of the operation, and FIG. 6 is an explanatory diagram of the operation in the conventional example. 19... Paper feed section, p... Paper, 20... Paper discharge section,
27... Main transport path, 29... Image forming section (transfer section)
, 31... Second U-turn path, 36... Re-supply conveyance path, 38... Front/back conversion path, 40... First U-turn path, 41... First accumulation section, 42...First take-out roller, 44...Second accumulation section, 45...Second take-out roller, 46...Third U-turn path. Applicant's agent Patent attorney Takehiko Suzue Figure 1 Figure 2 Figure 5 Applicant Delusion

Claims (2)

[Claims] (1) A main conveyance path that conveys the paper fed from the paper feed section to the paper discharge section, an image forming section that forms an image on one side of the paper while it is being conveyed along this main conveyance path, and this image forming section. a re-supply conveyance path for again supplying the paper with an image formed on one side to the image forming section; and a re-supply conveyance path branching from the re-supply conveyance path;
An image forming apparatus comprising: a front-back conversion path that converts the front and back sides of the paper by reversing the left and right sides of the paper with respect to the transport direction during transport, and joins the re-supply transport path. (2) The resupply conveyance path includes a first U-turn path for U-turning the paper on which an image has been formed on one side in the image forming unit, and a temporary accumulation of the U-turned paper through this first U-turn path. a first stacking section; a first take-out means for taking out sheets of paper stacked in the first stacking section one by one in a direction parallel to the paper feeding direction in the image forming section; and the first take-out means; and a second U-turn path for making a U-turn on the paper taken out by the user and transporting the sheet to the image forming section. a second stacking section that temporarily stacks the sheets carried out from the branching path; and a second stacking section that takes out the sheets stacked in the second stacking section one by one in a direction perpendicular to the paper feeding direction in the image forming section. Claim 1 characterized in that it is constructed by providing a take-out means and a third U-turn path for U-turning the paper taken out by the second take-out means and conveying it to the first stacking section. The image forming apparatus according to item 1.