JPH0743959A - Electrophotographic printer - Google Patents

Abstract

PURPOSE:To provide a compact electrophotographic printer provided with a both-side image forming function that the up and down relations of the front and rear surfaces of printing output information are matched. CONSTITUTION:In this electrophotographic printer provided with an image forming means 2 developing the electrostatic latent image of a photoreceptor 2A, a transfer means 4 transferring an image on the photoreceptor 2A on a paper sheet, fixing means 5 and 12 fixing the transferred image and an ejecting means ejecting the paper on which the image is fixed by the fixing means 5 and 12 outside, a inverse carrying path 20A actuated in accordance with reverse working by the photoreceptor 2A, to guide the paper P after passing the transfer means 4 and feed the leading edge part of the paper P to the paper feeding side of the transfer means 4 again, in a state where the paper P is turned upside down is provided, the first fixing means 5, a paper carrying means 6 and an inverse paper carrying means 9 are successively equipped along the inverse carrying path and the fixing means 12 is equipped in proximity of the first feeding side of the paper P to the transfer means 4 is equipped as well.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic printer, and more particularly to an electrophotographic printer having a double-sided image forming function.

[0002]

2. Description of the Related Art A conventional electrophotographic printer having a double-sided image forming function is constructed such that after one side of a recording medium is subjected to image forming processing, the front and back sides of the recording medium are reversed and the image forming processing is performed again. Has been done. An example of such a conventional technique is shown in FIG.

In the conventional example shown in FIG. 3, a mechanism for switching back the recording medium P is provided in the conveying means of the recording medium P, whereby the front and back of the recording medium P are reversed.

That is, in the conventional example shown in FIG. 3, when image data is sent from a host machine or the like, the recording medium storage means 51 first sets the recording medium P to the image forming means 5 including a photoconductor.
Transport to 2. The recording medium P is the image forming means 5
2. By the exposure means 53 and the transfer means 54, the recording medium P
An image is formed by a developer on one side of the.

Thereafter, the recording medium P is subjected to a fixing process by the fixing means 55 and conveyed to the conveying means 56. Then, the switchback type conveying means 57 and the conveying means 58.
Thus, the recording medium P is turned upside down and conveyed again to the image forming unit 52. As a result, the recording medium P is
This time, an image forming process is performed on the back surface, and the sheet is conveyed toward the discharge tray 60 via the fixing unit 55, the conveying unit 56, and the discharging unit 59 in order.

On the other hand, in Japanese Patent Laid-Open No. 63-54060, when the recording medium is subjected to double-sided image forming processing, the photosensitive member is moved in a normal reverse rotation with respect to one of the surfaces, and The image information to be subjected to latent image processing is sent from the trailing edge of the image information to perform latent image processing for one page, and then the photoconductor is returned to normal rotation to perform transfer processing and fixing processing. It is disclosed that a good screen image forming result is obtained in which the upper and lower relationships of the above are matched.

[0007]

However, in the case of FIG. 3 in the conventional example, since the leading end and the trailing end with respect to the conveyance direction of the recording medium are also reversed after reversing, the print information is upside down on the front surface and the back surface. That is, it is inconvenient to create a general left-closed document in which the top and bottom of the front surface and the back surface are the same.

Further, in the one disclosed in Japanese Patent Laid-Open No. 63-54060, the paper reversing mechanism uses the same principle as that of FIG. 3 described above, and the defect in FIG. It has an advantage that information is printed out in the same direction on the front surface and the back surface.

However, this Japanese Patent Laid-Open No. 63-5406
In the one described in Japanese Patent No. 0, the photosensitive member is rotated in the reverse direction when an electrostatic latent image is formed, and the operation of developing the electrostatic latent image and fixing it on the paper is performed at normal rotation. If the electrostatic latent image for one page is not completely formed on the photosensitive member, the next development and fixing process cannot be started, so that the continuous operation is interrupted between the electrostatic latent image process and the developing and fixing process, so that printing is performed. There is a disadvantage that the speeding up of output is significantly impaired, and at the same time, the photosensitive member cannot be moved to the next developing and fixing steps unless the electrostatic latent image for one page is completely formed. It had the drawback of being possible.

Further, in each of the above-mentioned conventional examples, the space required for switching back the recording medium must be increased in proportion to the size of the recording medium on which the image forming process is performed. Therefore, in the above-mentioned conventional example, there is a problem in that the size of the printer apparatus itself is hindered.

[0011]

SUMMARY OF THE INVENTION It is an object of the present invention to improve the inconvenience of the conventional example, reduce the size, and provide an electronic device having a double-sided image forming function capable of matching the vertical relationship of the front and back sides of print output information. Its purpose is to provide a photographic printer.

[0012]

SUMMARY OF THE INVENTION In the present invention, a cylindrical photosensitive member, and an exposing means for forming an electrostatic latent image on the photosensitive member,
An image forming means for developing the electrostatic latent image on the photoconductor, a transfer means for transferring the image formed on the photoconductor onto a predetermined sheet, and a fixing means for fixing the image transferred by the transfer means, Ejecting means for ejecting the paper on which the image is fixed by the fixing means to the outside. Further, the transfer means, the fixing means, and the discharging means are arranged along the paper traveling path. The fixing means are arranged at two places.

Further, the sheet which has been operated in response to the reversal operation by the photoconductor and has passed through the transfer means is guided, and the same leading edge portion of the same sheet is again turned upside down in the state where the sheet is turned upside down. An inversion conveyance path is provided for feeding to.
Along the reverse conveyance path, the first fixing means of the fixing means, the sheet conveying means, and the reverse sheet conveying means are sequentially installed.

At the first loading side of the paper with respect to the transfer means,
A configuration is adopted in which a final discharge path for discharging the paper after the completion of transfer on the back surface is provided, and a second fixing unit for fixing the transfer image on the back surface is provided in this final discharge path. This aims to achieve the above-mentioned object.

[0015]

[Operation] When the passage of the recording medium P at that point is detected by the sheet detecting means 10 present in the reversing sheet conveying means 9, the control unit (not shown) of the printer causes the photosensitive member of the image forming means 2 to be exposed. The body 2A is instructed to make a regular reverse rotational movement. At the same time, the various mechanisms inside the image forming means 2 are also set so as to perform the image forming operation when the recording medium P is conveyed in the reverse direction.

Then, the recording medium P conveyed to the image forming means 2 is again subjected to the image forming process on the back side and the front end in the conveying direction is the same as the image forming process on the front side. . Then, the recording medium P is the conveyance path selection guide 11
The conveyance path is changed by and is conveyed to the second fixing unit 12. After that, the recording medium P is subjected to a fixing process by the second fixing means 12, and thereafter, the recording medium P is ejected to the final sheet ejection tray 15 by the final ejection roller 13.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. In the embodiment shown in FIGS. 1 and 2, a cylindrical photosensitive member 2A, an exposing unit 3 for forming an electrostatic latent image on the photosensitive member 2A, and an image for developing the electrostatic latent image on the photosensitive member 2A. Forming means 2, transfer means 4 for transferring the image formed on the photoconductor 2A onto a predetermined sheet, and first and second fixing means 5, 12 for fixing the image transferred by the transfer means 4. Further, it is provided with first and second discharging means for discharging the sheet on which the image is fixed by the first and second fixing means 5, 12 to the outside.

The transfer means 4, the first and second fixing means 5 and 12, and the first and second discharging means are arranged along the paper traveling path 20. Further, the paper P that has been operated in response to the reversing operation by the photoconductor 2A and has passed through the transfer means 4 is guided, and the same leading edge of the same paper P is again turned upside down with the transfer means 4 being turned upside down. A reversing conveyance path 20A for feeding the sheet to the sheet delivery side is provided. The above-mentioned first fixing unit 5, sheet conveying unit 6, and reversing sheet conveying unit 9 are sequentially installed along this reversing conveying path.

A final discharge path 2 for discharging the paper P after the completion of the transfer on the back surface to the first carrying-in side of the paper P to the transfer means 4.
0C is provided, and the second discharge means 20C is equipped with a second fixing means 12 for fixing the transferred image on the back surface.

Between the sheet conveying means 6 and the reversing sheet conveying means 9 provided along the reversing conveying path 20A, a sheet intermediate discharge roller 7 for a sheet for which printing on one side is completed is provided. Further, the sheet P fed into the transfer means 4 is guided between the final discharge path 20C and the transfer means 4 described above, and the sheet P sent out from the transfer means 4 toward the final discharge path 20C described above is guided. A conveyance path selection guide 11 for guiding is provided.

The conveyance path selection guide 11 is variably changed to change the conveyance path of the recording medium P as shown by reference characters a and b in FIG. Specifically, the conveyance path selection guide 11 has a form a when the recording medium P is conveyed from the recording medium storage unit 1 to the image forming unit 2, and the recording medium P is separated from the image forming unit 2. When the recording medium is conveyed to the second fixing unit 12, the recording medium has a form b and the recording medium conveyance path is changed.

Further, in FIG. 1, reference numeral 1 indicates a recording medium storing means, and reference numeral 1A indicates a feeding roller for feeding a paper P which is a recording medium. Further, reference numeral 15 indicates a final paper discharge tray, and reference numeral 14 indicates an intermediate paper discharge tray arranged outside the above-described paper intermediate paper discharge roller 7. A switching guide 8 is provided at the above-mentioned reversal sheet conveying means 9 portion toward the intermediate sheet discharge tray 14. Further, reference numeral 13 indicates a final paper discharge roller.

The image forming means 2 surrounds the above-mentioned photoconductor and is internally provided with a load charging means, a developer, a developing sleeve, a developer stirring means and a developer removing means.
Then, an image forming process is performed by adding a charge removing process and an exposing process to this. The image forming means 2 is provided with a reverse rotation mechanism for the photoconductor 2A in addition to a regular rotation mechanism for the photoconductor 2A, and even if the recording medium P is conveyed in the regular reverse direction as described above, An image forming process can be performed on the recording medium P.

The intermediate sheet discharging roller 7 serves as a discharging means for discharging the recording medium P from the printer main body to the discharging tray 14 when forming an image on only one side, but when forming a double sided image, It becomes a part of the reversing conveyance path 20A when combined with the switching guide 8. Also, reference numeral 1
Reference numeral 0 is a paper detecting means for detecting whether or not the recording medium P has passed the point.

Next, the operation of the above embodiment will be described.

First, when image information is sent to the printer from a higher-level machine or the like, the recording medium P is conveyed by the recording medium storage means 1 to the image forming means 2. At this time, the transport path changing means 11 is assumed to be in the state shown in FIG. The recording medium P conveyed to the image forming means 2 is formed with an image on one side by a developer by the image forming means 2, the exposing means 3 and the transferring means 4.

Then, after being conveyed to the first fixing means 5 and subjected to a fixing process, it is conveyed to the sheet intermediate discharge roller via the conveying means 6. Here, when the image information is for only one side, the switching guide 8 is in the open state, and the recording medium P is discharged to the intermediate discharge tray 14 by the sheet intermediate discharge roller 7. However, when the image information is for both sides, the switching guide 8 is in a closed state, and the sheet intermediate discharge roller 7 becomes a part of the reverse conveyance path 20A in combination with the switching guide 8 as described above.

Next, the sheet detecting means 10 existing in the reverse sheet conveying means 9 portion detects whether or not the recording medium P has passed at that point. When the passage of the recording medium P is detected, a control unit (not shown) of the printer commands the photoconductor 2A of the image forming unit 2 to make a regular reverse rotational movement. Along with that, the various mechanisms inside the image forming means 2 are also set so as to perform the image forming operation when the recording medium P is conveyed in the reverse direction.

Then, again, the recording medium P conveyed to the image forming means 2 is subjected to the image forming process on the back side and in the same state as the image forming process of the front side in the conveying direction. It The recording medium P is the conveyance path selection guide 1
The conveyance path is changed by 1 and is conveyed to the second fixing unit 12. At this time, the transport path selection guide 11 is set to the state shown in FIG. Thereafter, the recording medium P is subjected to a fixing process by the second fixing means 12, and thereafter,
The sheet is ejected to the final sheet ejection tray 15 by the final ejection roller 13.

Here, the transport distance from the transfer means 4 to the paper detection means 10 is larger than the maximum length in the sub-scanning direction of the recording medium P which enables the image forming processing by this printer. Is set to.

The storage means for temporarily storing the image information is, for example, some obstacle in the process during the back surface image forming process of each of the transport path selection guide 11, the second fixing means 12 and the final discharge roller 13. It is necessary to secure the image information in advance in consideration of the case where the image forming process is interrupted due to the occurrence of the above, and from this viewpoint, it is necessary to be able to store this information (both front and back sides). The one with a large capacity is used.

Further, since this apparatus is equipped with two fixing means, it is equipped with an exhaust heat mechanism which takes into account the temperature rise in the apparatus due to these fixing means.

[0033]

Since the present invention is constructed and functions as described above, according to the present invention, the photosensitive member has a regular reverse rotation mechanism, and other processes necessary for image forming processing are regular for the recording medium. Since the image forming process can be performed even in the case of the reverse conveyance of, the front and back sides of the recording medium can be reversed and conveyed to the image forming means without reversing the conveying front end. By providing a control unit that controls the mechanism, it is possible to obtain good double-sided image formation results in which the top and bottom of the front surface and back surface are the same, and the transport distance required for reversing the front and back surfaces of the recording medium is It is possible to reduce the size, and since it is possible to operate continuously, it is possible to sufficiently reduce the time required for one recording medium during double-sided image forming processing, which is an excellent power supply that has never existed before. It is possible to provide a photographic printer.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an operation example of the conveyance path selection guide disclosed in FIG.

FIG. 3 is an explanatory diagram showing a conventional example.

[Explanation of symbols]

 1 Recording Medium Storing Means 2 Image Forming Means 2A Photosensitive Body 3 Exposure Means 4 Transfer Means 5 First Fixing Means 6 Paper Conveying Means 7 Intermediate Paper Ejecting Rollers 8 Switching Guides 9 Reversed Paper Conveying Means 10 Paper Detecting Means 11 Conveying Path Selection Guides 12 Second Fixing Means 13 Final Paper Ejection Roller 20 Paper Traveling Path 20A Reverse Transport Path 20C Final Ejection Path

Claims (3)

[Claims] 1. A cylindrical photosensitive member, an exposing unit for forming an electrostatic latent image on the photosensitive member, an image forming unit for developing the electrostatic latent image on the photosensitive member, and an image forming unit formed on the photosensitive member. A transfer unit configured to transfer the formed image to a predetermined sheet, a fixing unit configured to fix the image transferred by the transfer unit, and a discharging unit configured to discharge the sheet on which the image is fixed by the fixing unit to the outside. In an electrophotographic printer in which the transfer means, the fixing means, and the discharging means are arranged along a paper traveling path, the fixing means is arranged at two places, and the fixing means operates in response to the reversal operation by the photoconductor. A reversing conveyance path is provided for guiding the sheet that has passed through the transfer means, and again feeding the same leading edge portion of the same sheet to the sheet delivery side of the transfer means in the state where the sheet is turned upside down, and along the reversal conveyance path. The above A first fixing unit among the units, a sheet conveying unit, and a reversal sheet conveying unit are sequentially provided, and the sheet after the completion of transfer on the back side is discharged to the first loading side of the sheet with respect to the transfer unit. An electrophotographic printer, characterized in that a final discharge path is provided, and the final discharge path is equipped with a second fixing means for fixing the transferred image on the back surface. 2. A paper discharging means for the paper on which printing on one side is completed is provided between the paper carrying means and the reverse paper carrying means provided along the reverse carrying path. The electrophotographic printer according to item 1. 3. A conveyance path selection for guiding a sheet sent to the transfer means between the final discharge path and the transfer means and guiding a sheet sent out from the transfer means toward the final discharge path. The electrophotographic printer according to claim 1, further comprising a guide.