JP2901975B2 - Double-sided image forming method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a double-sided image forming method, and more particularly to a double-sided image forming method applicable to each system such as a copying machine, a laser printer, and a facsimile. (Prior Art) As a method of performing double-sided recording by sequentially transferring one side and the back side of a transfer receiving member which is a recording sheet, the transfer receiving member is fed from a paper feed tray to a transfer portion to transfer an image, and the single-side transfer is performed. The transferred member afterward is sent to a fixing unit, and the transferred member having completed the fixing process in the fixing unit is sent to a reversing unit. After the reversing unit in the reversing unit, the sheet is again fed to the transfer position. A method is known in which an image is transferred to both surfaces of a member to be transferred by transferring the image to the back surface of the member. The following method is specifically adopted among the above methods. This is a method in which one side of a large number of members to be transferred is first continuously transferred and reversed, then stored in an intermediate stack portion, and then the back side is continuously transferred. However, the above-described method is convenient when the same image is transferred to all pages, but when recording a different image on each of the transfer-receiving members, the above-described cycle must be performed every several sheets. There is a problem that the copy speed becomes slow and an intermediate stack portion having a mechanical structure is required, which causes an increase in cost. (Object) It is therefore an object of the present invention to provide a double-sided image forming method capable of realizing this with a simple and inexpensive configuration while increasing both-side recording speed. (Structure) In order to achieve the above object, the present invention is to transfer a member to be transferred from a paper feed tray to a transfer unit to transfer an image to the surface of the member to be transferred, and to transfer the member to be transferred after the surface transfer. Sending to the fixing unit, the transferred member having completed the fixing process in the fixing unit is sent to the reversing conveyance path, after reversing the front and rear in the reversing conveyance path, and again fed to the transfer position, In a double-sided image forming method in which an image is transferred to the back surface of a member to be transferred to obtain an image on both surfaces of the member to be transferred, the first member to be transferred having the surface transferred is moved up and down in the reversing conveyance path. After the reversal, n sheets are sequentially transferred to the surface of the member to be transferred until the back surface is transferred, and then the back surface is transferred to the first member to be transferred. A surface transfer is performed on a member to be transferred next to the member to be transferred, Hereinafter, the backside transfer is performed next to the frontside transfer,
After the backside transfer, the process of performing the frontside transfer on a new member to be transferred is repeated to obtain a double-sided image.
Is set to 0 or any positive integer, and a plurality of modes for double-sided image formation can be executed. It is characterized in that the mode is changed to another mode among the plurality of modes and the formation of the double-sided image is continued. Hereinafter, a specific description will be given based on an embodiment of the present invention. First, as an example of a recording apparatus suitable for implementing the present invention,
Image data sent from a host system (computer, word processor, etc.) is converted into laser modulation data and a paper feed path,
A laser printer having a paper ejection path, an image data controller (hereinafter referred to as a controller) for converting to a print mode (duplex mode or the like) selection signal, and a sequence driver unit for controlling a printing operation according to a selection signal and a print request signal from the controller. The outline will be described with reference to FIG. When all the data of the print start is prepared by the controller according to the data from the host system, a signal for selecting a paper feed path and a paper discharge path is sent to the sequence driver, and further a print mode selection signal is sent. When the print start signal is sent, the sequence driver starts print sequence control. When the print sequence is started, one of the paper feed rollers 19, 20, and 74 is driven at a predetermined timing, and any of the upper paper feed cassette 2, the lower paper feed cassette 3, or the large-capacity paper feed tray LCIT7 is driven. Paper feeding is started from the selected one, and paper as a member to be transferred is fed by one of the paper feeding rollers 21, 22, and 75, and is temporarily stopped in a state where the paper abuts against the registration roller 23. On the other hand, the photosensitive drum 29 rotates in the direction of the arrow in FIG.
The surface charged by the charging unit charger 34, the surface charged by the laser writing unit 40 is irradiated with a laser beam modulated in accordance with image data by the laser writing unit 40 while performing main scanning in the drum axis direction. To form a latent image. The latent image is developed with the toner from the developing unit 35, and is transferred to the paper fed by the registration roller 23 at a predetermined timing.
Transcribe by The transferred paper is peeled from the photosensitive drum 29, and is conveyed to the fixing device 31 by the conveying belt 24.
Then, the sheet is sent to the sheet discharge section by the sending roller 25. At this time, the path of the paper is selected according to the rotation position of the paper path changing pawls 32, 33, 81, and the upper discharge tray 84, the lower discharge tray 85, or the rear discharge tray 5 of the mass discharge unit 8 is selected. Discharge to one of them. Normally, one of the trays of the mass discharge unit 8 is selected, and the printed paper is face-down discharged. However, in a special case such as when a strong paper such as an envelope or a postcard is used. Then, the rear discharge tray 5 is selected. However, when the rear discharge tray 5 rotates about the shaft 5A and rotates in the direction indicated by the arrow in FIG. The paper tray 5 cannot be selected. When double-sided image formation is selected, paper printed on one side is sent to the double-sided unit 6 in the table 10 by the lower transport roller 28. Then, after being fed into the reversing conveyance path 65, which is a reversing section, the conveyance direction is reversed, and the sheet is conveyed to the standby conveyance path 66. Is printed on the other side in the same manner as described above, and then discharged to one of the discharge trays. Next, a two-sided print mode including an embodiment of the present invention will be described. The duplex printing mode for printing (printing) on the front and back sides of print paper using the duplex unit 6 is MODE
There are three modes, 1, MODE2 and MODE3, and these modes can be selected and executed as needed. The type of MODE is determined by the maximum number of sheets that can be stored in the main unit and the duplex option. In this embodiment, the mode is set up to MODE3.However, when the entire length of the paper transport path is longer, more MODEs are required. Can be set. The order of printing on the front and back sides of the paper in these three modes is printed on each paper in the order of printing on the front side of the paper.
The numbers (1, 2, 3, etc.) (corresponding to the paper IDs) are given as follows. MODE1: # 1 table, # 1 back, # 2 table, # 2 back, # 3 table, # 3
Back ... MODE2: # 1 table, # 2 table, # 1 back, # 3 table, # 2 back, # 4
Table, # 3 back ... MODE3: # 1 table, # 2 table, # 3 table, # 1 back, # 4 table, # 2
Back, # 5 front, # 3 back, # 6 front, # 4 back ... The printing process of each mode is shown in FIGS.
FIGS. 3A and 3B each schematically show a transport path of a paper (hereinafter, referred to as “paper”) as a member to be transferred used in double-sided printing, and indicate positions of odd-numbered paper. The position of the even-numbered paper is indicated by a thick solid line with a thick broken line. In FIG. 3A, parts corresponding to those in FIG. 4 are denoted by the same reference numerals, but the same reference numerals are used in other figures, so that the reference numerals are omitted. First, referring to FIGS. 3A to 3F, the printing process of MODE1, which can be called the prototype of the present invention, will be described. Although any paper feed device may be selected, here, an example in which the upper paper feed cassette attached to the printer body is selected, the paper feed of the first sheet # 1 from the upper paper feed cassette is started. (A), first print on the surface (B). The paper # 1 is sent to the reversing conveyance path 65 of the duplex unit (C), the conveyance direction is reversed and sent out to the standby conveyance path 66 (D). From there, this paper # 1 is again fed to the transfer position through the common paper feed path from LCIT7 (E), and then printed on the back side (F), and paper # 1 that has been printed on both sides is selected. To the output tray that has been set. Similarly, the second and subsequent paper sheets are sequentially printed on the front surface and the back surface and sent out. Next, referring to FIGS. 1A to 1H, a printing process of MODE2 as one embodiment of the present invention will be described. This time, in a case where the lower paper cassette is selected as the paper feeding device, paper feeding is started from the lower paper cassette, and printing is first performed on the front surface (A). The paper # 1 is sent to the reversing conveyance path of the duplex unit, and at the same time, the feeding of the second paper # 2 is started (B). Then, the transport direction of the paper # 1 is reversed and sent out to the standby transport path, and at the same time, printing is performed on the surface of the paper # 2 (C). Thereafter, the paper # 1 is fed again to the transfer position, and the paper # 2 is sent again. Into the reversing transport path. (D). At the same time that paper # 2 is sent to the standby conveyance path,
Printing is performed on the back side of paper # 1 (E). Then, when the paper # 1 on which double-sided printing has been completed is sent to the selected discharge tray, the third paper # 3 is subsequently fed and printed on the front side (F). Thereafter, the paper # 3 is fed into the reversing conveyance path, and the paper # 2 is fed again to the transfer position, printed on the back surface (G), and sent to the selected discharge tray. Next, the fourth paper # 4 is fed and printed on the front side, and at the same time, the paper # 3 is sent out to the standby conveyance path (H). Thereafter, printing on the back side of the paper having been printed on the front side and printing on the front side of the new paper are alternately performed. Next, referring to FIGS. 2A to 2L, a printing process of MODE3 as one embodiment of the present invention will be described. This time is an example in which LCIT7 is selected as the paper feeding device, and the feeding of the first paper # 1 from LCIT7 is started.
(A), first print on the surface (B). At the same time that the paper # 1 is sent to the reversing conveyance path,
Printing is performed on the surface of the second paper # 2 (C), and then when the paper # 1 is sent out to the standby conveyance path, the paper # 2 is sent to the reversing conveyance path, and is printed on the surface of the third paper # 3. Print (D). Thereafter, the paper # 1 is again fed to the transfer position through the paper feeding path, and at the same time, the paper # 2 is sent to the standby conveyance path, and the paper # 3 is sent to the reversing conveyance path (E). Then, while printing on the back of paper # 1, 4
The sheet # 4 is fed from LCIT (F). Then
At the same time as the paper # 1 is sent to the selected discharge tray, printing is performed on the surface of the paper # 4, the paper # 2 is sent to the paper feed path, and the paper # 3 is sent to the standby conveyance path (G). . Subsequently, the paper # 4 is sent to the duplex unit and printed on the back side of the paper # 2, and at the same time, the feeding of the fifth paper # 5 is started (H). Then, printing is performed on the surface of the paper # 5, and the paper 4 is sent to the reverse conveyance path (I). Next, paper # 3 is sent to the paper feed path, and paper # 4 is sent to the standby conveyance path (J). Thereafter, printing is performed on the back surface of the paper # 3 while feeding the paper # 5 into the reversing conveyance path, and the feeding of the sixth paper # 6 is started (K). When printing on the surface of the paper # 6, the paper # 4 is sent out to the paper feeding path, and the paper # 5 is sent out to the standby carrying path (L). Thereafter, similarly, the printing on the front side of the new paper and the printing on the back side of the paper two sheets before are performed alternately. The print speeds in the three double-sided print modes are as follows: MODE1 <MODE2 <MODE3 MODE2 is 1.5 times or more of MODE1, and MODE3 is 2 times or more of MODE1. Therefore, when performing large-volume double-sided printing, use MODE
3 is good to choose. Furthermore, each mode can be changed even during printing. For example, from MODE1 to MODE3 and from MODE3 to MOD
This is when changing to E2. (MODE1 specified) # 1 table, # 1 back, # 2 table, (changed to MODE3) # 3 table, # 4 table, # 2 back, # 5 table, # 3 back, # 6
Front, # 4 back, (changed to MODE2) # 5 back, # 7 front, # 6 back... Although the embodiment in which the present invention is applied to a laser printer system has been described in detail above, the present invention is not limited to this, and various other printer systems, high-function copying systems using digital copying machines, facsimile systems, etc. Can be similarly applied to the various image forming systems. (Effect) In the present invention, a single-sided transfer is performed by sending a new transferred member to the transfer unit by utilizing the time during which the transfer-receiving member, which has already completed one-side transfer, is being subjected to reversal at the reversing unit or the like. Because of this, the time required for reversal can be effectively utilized, and therefore, the speed of double-sided image formation can be increased. In addition, since each mode can be changed even while printing is being performed, efficient printing can be performed in accordance with the status of data transfer from the host system or the like.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 to 3 are views for explaining a transfer process of a member to be transferred on a transport path, and FIG. 4 is an explanatory view of a main part configuration of a laser printer suitable for carrying out the present invention. is there.

Claims (1)

(57) [Claims] The transferred member is fed from the paper feed tray to the transfer unit to transfer an image to the surface of the transferred member. The transferred member after the surface transfer is sent to the fixing unit, and the fixing process is completed in the fixing unit. The transferred member is transferred to a reversing conveyance path, and after being reversed in the reversing conveyance path, the sheet is again fed to the transfer position, and the image is transferred to the back surface of the transfer member by transfer. In the double-sided image forming method of obtaining images on both sides of the member, after the front-transferred first member to be transferred is reversed by the reversing conveyance path, before the back-side transfer is performed. The front surface transfer is sequentially performed on the n transfer members, the back surface transfer is performed on the first transfer member, and then the surface transfer is performed on the transfer member next to the n transfer members. After that, the back side is transferred after the front side transfer. After the transfer, a step of performing surface transfer on a new member to be transferred is repeated to obtain a double-sided image, and a plurality of modes for double-sided image formation with n being 0 or any positive integer can be executed, While executing the duplex image forming mode by selecting an arbitrary mode from the plurality of modes, the mode is changed to another mode among the plurality of modes as necessary to continue the duplex image formation. Method.