JPH11139646A - Picture image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reverse a sheet without putting it out of a device at the time of reversing the sheet to form a picture image on the other surface of the sheet on one surface of which a picture image is formed. SOLUTION: This device is furnished with a picture image formation device main body having a picture image forming means to form a picture image on a sheet, an option unit free to install on the device main body, a feeding passage to feed the sheet to the picture image forming means, a discharge passage to discharge the sheet on one surface of which a picture image is formed out of the device, a reversing carrier passage to reverse the sheet to form a picture image on the other surface of the sheet, a carrier passage 18 to carry the sheet reversed in the reversing carrier passage to a feeding passage, a change-over means 19 to deliver the sheet to either of the discharge passage and the reversing carrier passage and a reciprocally rotating roller pair 33 to return after delivering the sheet to the reversing carrier passage. Additionally, the reversing carrier passage 29 is provided on the picture image formation device main body, and the reversing carrier passage below it is provided on the option unit.

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 such as a copying machine and a printer, and more particularly to an image forming apparatus having a sheet reversing mechanism.

[0002]

2. Description of the Related Art As shown in FIGS. 6 and 7, in a conventional image forming apparatus, based on image information read by an image reading unit A, a photosensitive drum 5 as an electrophotographic photosensitive member arranged in an image forming unit B is used. An electrostatic latent image is formed on the latent image, and the latent image is visualized by applying toner as a developer by a developing unit 16.

When an image is formed on one side of the sheet S, the sheet S fed from the cassette 2a provided in the image forming section B passes through the transport path 17 and serves as an image carrier of the image forming section B. The toner image inserted between the photosensitive drum 5 and the transfer roller 6 serving as a transfer unit and formed as described above is transferred to the sheet S by the transfer roller 6 and conveyed to the fixing device 12 where the image is fixed. Then, the fixed sheet S is discharged from the discharge unit D onto the discharge tray 14.

When an image is to be formed on both sides of the sheet S, an image is first formed on one side of the sheet S as described above, and the sheet S is fixed, and as shown in FIG. The sheet passes through the discharge roller pair 21 and is separated in the direction of the transport path B23 by the flapper 19 located at 19a.
A part of the sheet S is discharged onto the discharge tray 14 outside the apparatus by the pair of external discharge rollers 22. At the moment when the rear end of the sheet S has passed through the flapper 19, the switching means (not shown) switches the flapper to two points. The transport path 24 is moved to the position indicated by the chain line 19b.
Is formed, and the sheet S is passed through the transport path 24 and the transport path 25 by reversing the outer discharge roller pair 22 to reverse the front and back of the sheet S.

[0005] The inverted sheet S passes through the transport path 18, passes through the transport path 17 again, forms an image on the back surface, is fixed by the fixing device 12, and the switching means (not shown) moves the flapper 19 to the position 19a. The sheet is moved, passes through the formed conveyance path B23, and is discharged onto the discharge tray 14 outside the apparatus by the pair of external discharge rollers 22, thereby completing the duplex copying.

[0006]

However, in the prior art, when an image is formed in the double-sided copy mode, first, one side of the sheet is image-formed and fixed by the fixing unit, and the sheet is discharged by the discharge roller pair 22 to reverse the sheet. A part of the sheet is discharged out of the apparatus body.

For this reason, the user can intentionally touch or grab the partially discharged sheet, and in such a case, the image forming apparatus may display a jam and stop.

Further, if the discharge tray portion is covered with a cover or the like so that the user does not touch it intentionally, the sheets on the discharge tray are difficult to remove and the workability deteriorates.

In order to secure a space for reversing the sheet in the apparatus main body, for example, the cassette 2a
If a space is provided between the apparatus and the cassette 2b, it is necessary to increase the size of the apparatus main body, which causes a problem in compactness.

The present invention has been made in view of the above circumstances, and provides a sheet reversing path which does not require a large space in an image forming apparatus so that a sheet does not come out of the apparatus at the time of reversing. It is an object of the present invention to provide an image forming apparatus which prevents a jam or the like caused by touching by a user.

[0011]

In order to achieve the above object, a representative means according to the present invention is an image forming apparatus main body having an image forming means for forming an image on a sheet, and the image forming apparatus main body. An image forming apparatus comprising: an optional unit which can be mounted on the image forming apparatus; a feeding path provided in the image forming apparatus main body for feeding a sheet to the image forming means; A discharge path for discharging a sheet having an image formed on one side thereof by the means to the outside of the apparatus, and a reversing means for reversing the sheet for forming an image on the other side of the sheet having the image formed on one side by the image forming means. A conveying path, a conveying path provided in the image forming apparatus main body, for conveying the sheet inverted by the reversing conveying path to the feeding path, and a conveying path provided in the image forming apparatus main body; A switching unit for feeding a sheet on which an image is formed to either the discharge path or the reverse conveyance path, and a forward / reverse rotation roller pair provided on the reverse conveyance path and capable of normal / reverse rotation for returning after feeding the sheet And
The reverse transport path is provided so as to span both the image forming apparatus main body and the option unit, and the forward / reverse rotation roller pair is provided in the image forming apparatus main body.

According to such means, in the double-sided copy mode, the sheet can be conveyed to the feeding path by the reversing conveyance path and the conveyance path in the apparatus main body, and the sheet can be reversed without being taken out of the apparatus main body. In addition, it is possible to prevent the user from touching the sheet during the reversing operation, thereby preventing the occurrence of a jam or the like.

[0013]

[Embodiment 1] First, FIGS. 1 and 2
The overall configuration of the image forming apparatus according to the present invention will be described with reference to FIG. In FIG. 1, an image reading unit A for reading image information of a document is disposed at an upper portion of the image forming apparatus main body 1;
An image forming unit B that records an image corresponding to the image information on the sheet S is disposed below the image forming unit B.

Cassettes 2a and 2b for accommodating sheets S are arranged in the image forming unit main body 1. The sheets S fed out by pickup rollers 3a and 3b serving as sheet feeding means are separated by sheet separating means (see FIG. 1). (Not shown), the sheet is fed one by one, and is conveyed to the position of the photosensitive drum 5 which forms a part of the image forming means provided in the image forming section B.

A cassette pedestal C as an optional unit is installed at the bottom of the main body 1 of the image forming apparatus, and cassettes 2c, 2d, 2e and 2f are provided in the cassette pedestal similarly to the main body 1 of the image forming apparatus. It is arranged so that a large amount of sheets S can be stored.

Further, a reversing conveyance path 30 through which the sheet S passes is provided in the upper part of the paper discharge side of the cassette pedestal C. The reversing conveyance path 30 through which the sheet S passes is formed. A positioning pin (not shown) is provided at the upper part of the cassette pedestal C and a positioning hole (not shown) is provided at the lower part of the image forming apparatus main body 1 so as to match the outlet side. When the image forming apparatus main body 1 starts copying in the double-sided copy mode, the image information of the document set on the document table 15 is read by the image reading unit 8 by driving the scanning optical 7.

A laser beam L is emitted by a laser scanner 9 based on the image information read by the image reading means 8 to form an electrostatic image on the surface of the photosensitive drum 5. The toner is supplied and a toner image is formed and is visualized. At the same time, the sheet S supplied from the cassette 2b is positioned by the registration roller pair 4 and conveyed between the photosensitive drum 5 and the transfer roller 6, and the toner image formed on the photosensitive drum 5 by the transfer roller is placed on the surface of the sheet S. Transcribed. The transferred sheet S is transferred to the conveyor belt 11.
, And sent to the fixing device 12 where the fixing device 1
The toner image is fixed on the sheet S by being heated and pressed by the fixing roller 12a and the pressure roller 12b provided in the sheet S.

In FIG. 2, the fixed sheet S is conveyed by an inner discharge roller pair 21 and a roller driving means (not shown) provided in a paper discharge device D, and a flapper which is a switching means similarly provided. 19, passes through the conveyance path 26, passes through the roller pair 34, is directed downward by the flapper 32 in the conveyance direction, passes through the conveyance path 27, and is an elastic sheet 31 which is a switching means provided for branching. Through the pair of reversing rollers 33 to reach the reversing conveyance path 29. At this time, the position of the rear end of the sheet S is detected by sheet detection means (not shown), and the detected signal
The sheet S is conveyed by the pair of reversing rollers 33 until the sheet S passes through the elastic sheet 31. At the point when the sheet S passes, the sheet S is conveyed to the conveying path 18 by the pair of entrance rollers 35 by reversing the pair of reversing rollers 33, Inverted.

If the length of the sheet S is short, the reversal of the leading end of the sheet S is completed in the transport path 29 of the image forming apparatus main body 1, but if the length of the sheet S is long, The leading end passes through the transport path 29, and the cassette pedestal C
To the reversing conveyance path 30 and is reversed. Since the inverted sheet S forms an image on the back surface, the sheet S passes through the conveyance path 18, passes through the conveyance path 17 in the same manner as the image formation on the front side, is positioned by the registration roller 4, and forms an image in the image forming unit B. Then, the image is sent to the fixing device 12 by the conveyance belt 11 to fix the image, and the flapper 19 in the paper ejection device D is moved to the position of the flapper 19b in the two-dot chain line by the switching means (not shown), and the conveyance path B23 Is formed, and the sheet S passes through the conveyance path B23 and is discharged from the discharge tray 1 by the external discharge rollers 22.
4 and the double-sided copy is completed.

[Embodiment 2] Next, a second embodiment of the present invention will be described. 3 and 4 show the image forming apparatus main body 1.
7 is a cross-sectional view of a state in which a cassette pedestal is not installed at the bottom of the apparatus and a three-bin paper ejection tray apparatus E is attached to the apparatus main body.

In the present embodiment, the image forming apparatus main body 1
When the copy is started in the double-sided copy mode, an image is first formed on one side of the sheet S and fixed by the fixing device as in the first embodiment.

In FIG. 4, the fixed sheet S is transferred to a pair of inner discharge rollers 21 provided in a three-bin discharge tray device E.
And a roller driving means (not shown), which is guided to the flapper 19 at the position 19a provided similarly, and
6, through the pair of rollers 34, the flapper 42 at the position 42a forms a conveyance path 38, the sheet S passes through the formed conveyance path 38, further passes through the middle discharge roller 36, and serves as second switching means. The sheet S passes through the reversing conveyance path 39 formed by the flapper 43, passes through the roller pair 37, and reaches the conveyance path 40.

At this time, the position of the trailing edge of the sheet S is detected by sheet detecting means (not shown), and the sheet S is rotated by the middle discharge roller 36 until the trailing edge of the sheet S passes through the flapper 42 according to the detected signal. The flapper 42 is moved to the position 42b in the two-dot chain line by the switching means (not shown) when the
1 is formed, and at the same time, the sheet S is reversed and the sheet S passes through the conveyance path 41, passes through the entrance roller 35, and is conveyed to the conveyance path 18 in reverse. Since the inverted sheet S forms an image on the back surface, the sheet S passes through the conveyance path 17, is positioned by the registration roller 4, forms an image in the image forming unit B, and forms an image on the conveyance belt 11 in the same manner as the image formation on the front surface. The image is sent to the fixing device 12 to fix the image, and the flapper 19 at the position 19a in the paper discharge device D is moved to the position 19b in the two-dot chain line by the switching means (not shown) to form the transport path 23. The sheets S are stacked on the discharge tray 14 by the external discharge rollers 22 through the transport path 23, and the double-sided copy is completed. Note that the three-bin discharge tray device E including the discharge portion D may be configured as a two-bin discharge tray device F by dividing an external discharge tray portion.
In this case, a reversing mechanism for reversing the sheet is provided in the main body 1 of the image forming apparatus, and the transport path 39 and the transport path 40 in the two-bin discharge tray device F are used.

[Embodiment 3] FIG. 5 shows an image forming apparatus main body 1.
7 is a cross-sectional view showing a state in which a cassette pedestal is not installed at the bottom of the pedestal and a small pedestal F is attached as an optional unit. The small pedestal F has a cassette, and functions mainly as a frame. A reversing conveyance path 46 through which the sheet S passes is provided at the upper part of the paper discharge side of the small pedestal F. The positioning bin (not shown) is located at the upper part of the small pedestal F, and the positioning hole (not shown) is located at the lower part of the image forming apparatus main body 1 so that the lower surface exit side of the conveyance path 29 of the image forming apparatus main body 1 is aligned with the bottom. Position).

When copying is started in the double-sided copy mode in the image forming apparatus 1, an image is first formed on one side of the sheet S and fixed by the fixing device 12 as in the first embodiment. S is the transport path 2 in the paper discharge device D
6, the sheet S is reversed by the reversing pair of reversing rollers 33 passing through the conveying path 27, the conveying path 28, and the conveying path 29, and is conveyed to the conveying path 18 through the entrance roller pair 35.

Here, when the sheet S is long, the sheet S is sent to the transport path 29 by the pair of reversing rollers 33, further transported to the transport path 46 provided in the small pedestal F, and slid on the inner wall of the transport path 46. The position of the rear end of the sheet S is detected by sheet detection means (not shown), and the sheet S is conveyed until the rear end of the sheet S passes through the elastic sheet 31 according to the detected signal. Embodiment 1
Similarly, the sheet S is reversed by the reversal of the pair of reversing rollers 33, and is conveyed to the conveying path 18 through the pair of entrance rollers 35. The inverted sheet S is similar to the first embodiment,
An image is formed on the back surface, the image is fixed by the fixing device 12, and the sheet is discharged from the discharge tray 1 by the external discharge roller 22 through the transport path 23.
4 and the double-sided copy is completed.

[0027]

As described above, according to the present invention,
An image forming apparatus main body, an image forming apparatus main body, and a reverse conveying path for reversely conveying a sheet on which an image is formed on one side in a double-sided copy mode, and a pair of forward and reverse rotation rollers for returning the sheet after feeding the sheet into the reverse conveying path. By storing it inside the optional unit and paper discharge unit for
Reversing inside the device is possible in a small space, and the compactness of the device is not impaired, and the user does not have to take out a part of a long sheet during the double-sided copy, so that the user can touch it. Can prevent the occurrence of jams and the like.

[Brief description of the drawings]

FIG. 1 is an overall view of an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram of a main part of the image forming apparatus according to the first embodiment of the present invention.

FIG. 3 is an overall view of an image forming apparatus according to a second embodiment of the present invention.

FIG. 4 is a schematic view of a main part of an image forming apparatus according to a second embodiment of the present invention.

FIG. 5 is an overall view of an image forming apparatus according to a third embodiment of the present invention.

FIG. 6 is a diagram illustrating an example of a conventional image forming apparatus.

FIG. 7 is a diagram showing a main part of a conventional image forming apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 5 ... Photosensitive drum 6 ... Transfer roller 12 ... Fixing device 14 ... Discharge tray 16 ... Developing device 17 ... Supply path 18 ... Convey path 19, 32, 43 ... Flapper 21, 22 ... Discharge rollers 29, 39 ... Reverse conveyance Road 31: Elastic sheet 33, 36: Forward / reverse rotation roller

Claims (11)

[Claims] 1. An image forming apparatus comprising: an image forming apparatus main body having an image forming means for forming an image on a sheet; and an optional unit attachable to the image forming apparatus main body. A feeding path for feeding a sheet to the image forming means, and a discharge path provided in the image forming apparatus main body, for discharging a sheet on which an image is formed on one side by the image forming means to the outside of the apparatus. A reversing conveyance path for reversing a sheet to form an image on the other surface of the sheet on which an image is formed by the image forming unit; and a reversing conveyance path provided in the image forming apparatus main body and reversing the reversing conveyance path. A transport path for transporting a sheet to the feed path; and a sheet provided on the image forming apparatus main body and having the image formed on one surface thereof, in either the discharge path or the reverse transport path. And a pair of forward / reverse rotation rollers provided in the reverse transport path and capable of rotating forward and reverse for returning the sheet after feeding the sheet, wherein the reverse transport path includes the image forming apparatus main body and the optional unit. Wherein the pair of forward and reverse rollers is provided in the main body of the image forming apparatus. 2. The apparatus according to claim 1, wherein the feeding path is disposed on one side of a cassette in the apparatus main body, the reverse conveying path is disposed on another side of the cassette, and the conveying path is a cassette. An image forming apparatus, wherein the image forming apparatus is disposed on an upper part of a printer. 3. The image forming apparatus according to claim 1, wherein the switching unit is a flapper. 4. The image forming apparatus according to claim 1, wherein the option unit is provided below the image forming apparatus main body. 5. The image forming apparatus according to claim 4, wherein the option unit contains a cassette therein. 6. The image forming apparatus according to claim 4, wherein the option unit is a gantry. 7. An image forming apparatus comprising: an image forming apparatus main body having an image forming means for forming an image on a sheet; and a paper discharge unit provided in the image forming apparatus main body. A feeding path for feeding a sheet to the image forming unit, a discharge path provided in the image forming apparatus main body, and for discharging a sheet having an image formed on one surface by the image forming unit to the outside of the apparatus; A reversing conveyance path for reversing a sheet to form an image on the other surface of the sheet on which an image is formed by the image forming unit; and a sheet provided in the image forming apparatus main body and reversed by the reversing conveyance path. A conveyance path for conveying the sheet having the image formed on one surface thereof to the discharge path or the reverse conveyance path. And means, the image forming apparatus characterized by providing spanned the reverse conveying path for both the sheet discharge unit and the image forming apparatus main body. 8. The image forming apparatus according to claim 7, wherein the discharge unit is an optional unit that is detachable from the apparatus main body. 9. An image forming apparatus according to claim 7, wherein said switching means is a flapper. 10. The image forming apparatus according to claim 7, wherein a sheet discharge conveyance path in the sheet discharge unit forms a part of the reverse conveyance path. 11. The image forming apparatus according to claim 7, wherein the sheet discharging unit is provided with a pair of forward / reverse rotation rollers capable of forward / reverse rotation for feeding the sheet and returning the sheet.