JPH0519860B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a recording device configured to perform double-sided recording, and more specifically, the present invention can also cope with cases where incomplete paper feeding occurs. This constitutes a double-sided recording device like this.

[Prior Art] In a recording device that prints or copies on a sheet-like recording medium, double feeding, skew feeding,
Incomplete paper feeding, such as leading edge delay, may occur (hereinafter, these are collectively referred to as incorrect paper feeding). Recording is not performed at the correct position on a sheet-like recording medium that has been improperly fed, and furthermore, this is a cause of jams and the like.

In conventionally known double-sided printing apparatuses, the page order pattern for printing is strictly determined, so that it has not been possible to adequately deal with this illegal paper feeding. Alternatively, even if it is possible to correct the problem, in order to recover from the disturbance in the page order pattern of records caused by incorrect paper feeding, it is necessary to discard the sheet-like recording medium on the sheet conveyance path and to discard the discarded sheet-like recording medium. It was necessary to re-record the corresponding page. As a result, sheet-like recording media that have been recorded by normal paper feeding are also discarded, causing not only unnecessary waste but also an unnecessarily reduced throughput.

For example, in Japanese Unexamined Patent Publication No. 56-121056, image data of all pages are stored in a file, 2n+1, 2n-1,
..., 3 pages, 1 page are printed on the first side of the recording paper in order, the recording paper recorded on the first side is stored in the intermediate tray in order, and then the second side of the recording paper from the intermediate tray is printed.
A double-sided recording device is disclosed that prints pages 2n, 2n-2, . . . , 4, 2 in this order on one side. Since the image data of all pages are stored in this device, it is relatively easy to recover from an abnormal state such as a jam, but there is a problem in that the image data of all pages must be stored. Furthermore, the mechanical configuration such as an intermediate tray capable of storing a large number of recording sheets and a mechanism for reliably picking up recording sheets one by one from the intermediate tray becomes complicated.

Furthermore, in Japanese Patent Application Laid-Open No. 57-89771, after printing on the first side of the first recording paper, 2, 4, 6...
Although a double-sided recording device is disclosed that alternately performs recording on the first side of the first sheet and recording on the second side of the first, third, fifth, and so on sheets, it does not solve the above-mentioned problem caused by incorrect paper feeding. Nakatsuta.

[Objective] In view of the above-mentioned points, the first object of the present invention is to provide a recording system that automatically copes with incorrect paper feeding during double-sided recording and that does not affect the recorded medium. The goal is to provide equipment.

Furthermore, a second object of the present invention is to provide a recording apparatus configured to minimize reduction in throughput due to incorrect paper feeding during double-sided recording.

In order to achieve such an object, the present invention provides a recording apparatus capable of double-sided recording, which includes a control means configured to perform recording with a predetermined page relationship even when paper is improperly fed.

[Example] Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a sheet conveyance system of a duplex printing apparatus according to an embodiment of the present invention. In this figure, 1-1
1-2 is a paper feeding section, 1-2 is a pre-transfer conveyance path, 1-3 is a drum that forms a toner image to be transferred onto the surface of a sheet of paper using known electrophotographic technology, and 1-4 is a drum 1-
3 a transfer charger that transfers the toner image onto a sheet of paper, 1-5 a pre-fixing conveyance path, 1-6 a fixing device that fixes the toner image transferred onto a sheet of paper by heat and pressure, 1- 7 is a post-fixing conveyance path; 1-8 is a pre-reversal branching mechanism that branches the sheet conveyance path; 1-9
1-10 is a pre-reversing conveyance path, 1-10 is a reversing mechanism using three known rollers for reversing the front and back sides of sheets;
1-11 is a post-reversal conveyance path, 1-12 is a pre-stacker conveyance path, 1-13 is a stacker, 1-14 is a pre-stacker branching mechanism, and 1-15 is an auxiliary tray.

During double-sided printing, sheets fed from the paper feed section 1-1 are conveyed to the drum 1-3 via the pre-transfer conveyance path 1-2. The toner image formed on the drum 1-3 using a known electrophotographic technique is transferred onto a sheet of paper by corona discharge in a transfer charger 1-4, and then passes through a pre-fixing conveyance path 1-5. The image is then conveyed to the fixing device 1-6. After the image has been fixed on the first side in the fixing device 1-6, the paper is conveyed via the post-fixing conveyance path 1-7, passes through the pre-inversion branching mechanism 1-8 and the pre-inversion conveyance path 1-9, and then is transferred to the inversion mechanism. Sent to 1-10.

The single-sided printed sheet, which has been reversed in the reversing mechanism 1-10, is sent to the pre-transfer transport path 1-2 via the reversal transport path 1-11, and then transferred to the drum 1-3.
Then, image transfer on the back side (second side) is performed by the transfer charger 1-4 in the same manner as in the previous one-sided printing. Thereafter, it is sent to a fixing device 1-6 via a pre-fixing conveyance path 1-5, where the image on the second side is fixed. At this point, double-sided printing is complete.

After the double-sided printed sheet is fixed, it is transferred to the conveyance path 1-7.
From the pre-reversal branching mechanism 1-8, the pre-stacker transport path 1
-12 and the stacker front branching mechanism 1-14, and then loaded onto the stacker 1-13.

The operation for double-sided printing on a single sheet is as described above, but in reality, if you wait for the completion of double-sided printing on one sheet before starting printing on the next sheet, the conveyance path will be Due to the considerable length compared to the sheet length, a reduction in throughput occurs.

Therefore, in order to obtain the same throughput (that is, the number of pages that can be printed within a unit time) as when printing on one side, it is necessary to
It is necessary to pass the sheet through step 3. As a method for realizing such a function, in the present embodiment shown in FIG. 1, the time interval of paper feeding from the paper feeding section 1-1 is set to be twice the interval during one-sided printing. Furthermore, in this embodiment, after finishing printing on one side, the reversing mechanism 1-1
The sheet reversed by 0 is conveyed through the conveyance path 1-1 after being reversed.
1 to the pre-transfer conveyance path 1-2, it is configured to be intermediate between the unprinted paper immediately after being sent from the paper feeder 1-1 and the unprinted paper.

By operating in this way, from the pre-transfer conveyance path 1-2 to the drum 1-3, the transfer charger 1-4,
The transport path from the pre-fixing transport path 1-5, the fixing device 1-6, the post-fixing transport path 1-7, and the pre-reversing branching mechanism 1-8 includes sheets that have already been printed on the back side and sheets that have been printed on the first side. Sheets that have only been printed will flow alternately.

The pre-reversal branching mechanism 1-8 branches alternately arriving double-sided printed sheets and single-sided printed sheets to the pre-stacker conveyance path 1-12 or the pre-reversal conveyance path 1-9, respectively. .

In this case, the pre-transfer conveyance path 1-2, the drum 1-
3. Pre-fixing transport path 1-5, fixing unit 1-6, post-fixing transport path 1-7, pre-reversing branching mechanism 1-8, pre-reversing transport path 1-9, reversing mechanism 1-10, post-reversing transport path 1
The length of one transport path loop consisting of -11 must be an odd multiple of the sum of the length of the sheet in the transport direction and the interval between the sheets. If it is an even number, the sheet fed from the paper feed section 1-1 and the sheet from the post-reversal conveyance path 1-11 overlap on the pre-transfer conveyance path 1-2. This causes the inconvenience of getting used to it. In other words, after the first side of a certain sheet arrives at the position of drum 1-3, the odd-numbered side
This means that the second side of the sheet returns to the position of the drum 1-3.

In this embodiment described above, the distance between both sides of the sheet (i.e., the sheet after printing on the first side returns to the drum 1-3 again and the second side is printed is the drum). After passing through steps 1-3, M represents the number of sheets to which the sheet corresponds. Therefore, for example, when M=5, four new sheets will be printed after the first side is printed until the second side is printed again.

Further, when printing on only one side, it is necessary to stack the sheets on the stacker 1-13 with the printed side facing down in order to maintain the correct page order of the sheets. On the other hand, when printing on both sides, it is necessary to stack the paper with the second printed side facing down. That is,
To arrange the page order correctly when printing on both sides,
Of the pages to be printed on both sides of a certain sheet, it is necessary to print the latter page first. If 1
If we consider printing from page number, even-numbered pages will be printed before odd-numbered pages.

FIG. 2 is a schematic diagram illustrating the conveyance system shown in FIG. 1 and the state of sheets flowing thereon when the distance between both sides is 5. In this figure, the reversing mechanism 1-1
0, which is schematically expressed as "the section in which the sheet is reversed while passing through this section." Also, 2
-1 is sheet transport loop, 2-2-1 to 2-2
-5 is a sheet being conveyed. Here, the numbers without brackets written on both sides of each sheet are the page numbers printed or currently being printed on that side.
The number inside the bracket indicates the page number to be printed.

In Figure 2, unhatched sheet 2-2
-2 and 2-2-4 are not yet inverted,
Further, hatched sheets 2-2-1 and 2-2-3 indicate that they have been reversed. Furthermore, sheet 2-2-5, which has been hatched halfway, is
This indicates that the image is currently being reversed by the reversing mechanism 1-10.

FIG. 3 shows a schematic diagram of an offline printing system to which the present invention is applied.

In this figure, 3-1 is a magnetic tape (hereinafter abbreviated as MT) on which print information, control information, etc. are recorded, 3-2 is a magnetic information converter that converts information in MT 3-1 into an electrical signal, 3- 3 is a central processing unit (hereinafter abbreviated as CPU) that controls the entire system, 3-4 is a page buffer that stores print information for each page, and 3-5 is a page buffer under the control of CPU 3-3. 3-4 is printing hardware that transfers print information; 3-6 is a printing device that performs actual printing; 3-7 is a management register group consisting of a plurality of registers that stores various information necessary for printing each page; 3 -8 is a separation register group for separating the page information of each page sequentially created on the page buffer 3-4 into a page printed on the front side of the paper and a page printed on the back side during double-sided printing; 3-9 3-10 is a print register group that controls the order of the sides to be actually printed; 3-10 is a page pointer that indicates the last register set in the management register group 3-7; and 3-11 is a page pointer in the page buffer 3-4. A page counter 3-12 indicates the number of currently printable pages that have been created, and 3-12 is a register from the separate register group 3-8 that is set when new page information is created. 3-13 is a separate set pointer indicating the register to be printed, 3-13 is a separate read pointer indicating the register corresponding to the page currently being printed out of the separate register group 3-8, 3-14 is the print register group 3-9. , a print pointer indicating the register corresponding to the side currently being printed, 3-15 a print counter indicating the number of registers corresponding to the side to be printed among the print register group 3-9, 3-16 a double-sided interval M 3-17 is a copy number register that registers the number of copies (in other words, indicates how many copies of the same page are to be printed consecutively); 3-18 is the current number of copies of the same page. This is a copy copy number counter that indicates whether or not the number of copies has been printed.

4. FIGS. 1 to 3 show the relationships and structures of registers, pointers, etc. shown in FIG. 3.

Here, the contents of each register included in the management register group 3-7 (see FIG. 4, 1) are as follows: Page presence/absence flag 3-7-
1. A page buffer pointer 3-7-2 indicating the position on the page buffer occupied by the page indicated by the register; and other information necessary to print one page.

The contents of each register included in the separate register group 3-8 (see FIG. 4, 2) are stored in the separate management pointer 3-8-1 that represents the register in the management register group 3-7 that corresponds to the page indicated by the register. be.

The contents of each register included in the print register group 3-9 (see Fig. 4, 3) include a print flag 3-9-1 indicating whether or not to print the side indicated by the register, and page information corresponding to that side. Print management pointer 3-9-2 indicating a register in the management register group 3-7 having part number counter 3-9-3 that indicates the part number), and whether the side indicated by the register is an even numbered page (i.e., the side to be printed first) or an odd numbered page (i.e., the side to be printed second time) This is a page index 3-9-4 indicating whether or not the page is displayed.

Note that this index is alternately "even" and "odd" (i.e.,
even numbered pages, odd numbered pages).

The page buffer 3-4 is divided into a plurality of page buffers each corresponding to one page (see FIG. 4). In addition, management register group 3-
Each of the registers 7 has a one-to-one correspondence with each partial buffer of the page buffer, and the page buffer pointer 3-7-1 takes this correspondence (see FIG. 41).

The page buffer 3-4 and the management register group 3-7 store the information necessary to print one page, but these 3-4 and 3-7 are not necessarily the same.
There is no need to separate the information from the management register, and it is also possible to place various information on the management register in the page buffer. However, if the page buffer cannot be placed in main memory due to memory capacity limitations,
A page buffer that requires a large capacity can be placed on a large-capacity secondary storage medium (for example, a magnetic disk), and a group of management registers can be placed on the main memory.

Page information created on the page buffer 3-4 based on the information read from the MT 3-1 is created successively, such as a first page, a second page, and a third page. However, in a system such as the present embodiment, in which sheets for printing on the first side and sheets for printing on the second side flow alternately,
The order of pages to be printed is not consecutive. Therefore, a means to absorb and adjust this difference is required. The separation register group 3-8 and print register group 3-9 shown in FIG. 3 serve as this adjustment means. In other words, the separation register group 3-8 divides the pages created in order in the page buffer 3-4 (and the management register group 3-7) into even pages (i.e. pages printed on the first side) and odd pages (i.e. pages printed on the first side). , the page printed on the second side). On the other hand, print register group 3-
9 plays the role of adjusting the order of pages to be printed so that it follows a predetermined sequential pattern required for double-sided printing.

In order to adjust the printing order, the print register group 3-9 simulates the sheet pages (both sides) on the conveyance loop (see 2-1 in FIG. 2) during double-sided printing. Print pointer 3-14
The print register indicated by indicates the page currently being printed (see the third page on the sheet 2-2-3 shown in Fig. 2), and the print register indicated by the print pointer 3-14 is sequentially switched to start the conveyance loop. Corresponds to the movement of the paper above. And print register group 3-9
The above page order is the order of pages to be printed.

Prior to printing, each register group, pointer, and counter are first initialized. FIG. 5 shows a flowchart of initialization.

First, the page presence/absence flag 3-7-1 of the management register of interest is set to "absent" (step 5-1), and then various information of the management register is initialized, and all management registers are initialized. Repeat this until finished (steps 5-3, 5-
4).

In steps 5-5 to 5-7, print flag 3 of each register in print register group 3-9 is selected.
-9-1 are all set to "non", and all part number counters 3-9-3 are set to "1". Further, the page index 3-9-4 is correctly set so that even (even numbered pages) and odd (odd numbered pages) alternate.

In step 5-8, an appropriate register in the management register group 3-7 is set to the page pointer 3-10.
set correctly.

In step 5-9, page number counter 3-1
1 and print counter 3-15 are set to zero.

In step 5-10, the separate register group 3-7
Among the registers in , the register to be set first in creating the print information for the first page is set in the separate set pointer 3-12.

In step 5-11, the separate register group 3-8
Among the registers in , the register next to the register set as an initial value in the separate set register 3-12 is set in the separate read pointer 3-13. That is, this sets the register corresponding to the second page.

In step 5-12, print register group 3-9
Among the registers in
-14 as the initial value. This register is used for even numbered pages (i.e., page index 3-9).
-4 is "even").

In step 5-13, the double-sided spacing M determined depending on the size of the sheet is stored in the double-sided spacing register 3-16.
Set to .

In step 5-14, the copy part number counter 3-
18 is set to 1, and the initialization is completed.

After completing the initialization in this way, CPU3
-3 starts creating the page.

FIG. 6 is a flowchart showing the page creation procedure.

In condition determination steps 6-1 and 6-2, new pages are not created in the page buffer of pages that have not yet been printed.

In condition determination step 6-3, it is determined whether page creation is complete.

If there is data on MT3-1, CPU3
-3 reads the information on the MT3-1 via the device 3-2 (step 6-4), analyzes this and sets the page buffer pointer 3-7-2 in the management register.
Page information is created in the page buffer indicated by (specified by page pointer 3-10). Here, creating page information means registering print information on the page buffer and setting the page presence/absence flag 3-7-1 of the corresponding management register to "present".

Next, in step 6-5, the page number counter 3-11 is updated.

Furthermore, in step 6-6, the management register indicated by page pointer 3-10 is set in the separate register indicated by separate set pointer 3-12.
This means that the currently created page is registered in the separate register group 3-8.

In step 6-7, the separate set pointer is updated.

In steps 6-8 and 6-9, a management register for creating the next page information is searched. That is, while advancing the page pointer 3-10 by 1, the page presence/absence flag 3-7 of the management register is
-1, and repeat until the first management register whose page presence/absence flag is "absent" is found. After this, control returns to step 6-1 again.

If it is determined in step 6-3 that the printing information on MT 3-1 has been completed, control is shifted to determination in step 6-11.

In step 6-11, from the relative position of the separate set pointer and the separate read pointer. It is checked whether the current page is an odd numbered page or an even numbered page, and if it is an odd numbered page, page creation is ended. If it is an even page,
Control is transferred to step 8-12.

Here, the separate read pointer always points to an even page. Therefore, if the relative position of the separate read pointer and the separate set pointer (how far the former is ahead of the latter) is an even number, the page pointed to by the separate set pointer is also an even page, and therefore the current page is an odd number. Become. Furthermore, if the relative position is an odd number, the current page is an even number.

In step 6-12, page pointer 3-1
Create completely blank page information in the page buffer indicated by 0. The processing in step 6-12 is as follows:
MT3-1 print information is odd page (k page)
, the next even page (k+
This means creating a dummy page on page 1).

In this embodiment, even-numbered pages are printed before odd-numbered pages, and paper is fed when even-numbered pages are printed. Therefore, if there is no dummy (page k+1) to be printed in advance, page k,
The sheet on which page k+1 is to be printed is not fed. That is, for page k, drums 1-3
Although a toner image is formed thereon, there is no paper to transfer it to, so as a result, page k will not be printed.

By the judgment in step 6-11 and the processing in step 6-12, even if
Even if the print information on -1 ends on an odd numbered page, by creating a dummy even numbered page,
It is possible to prevent missing pages as described above. Further, if the last page is an even numbered page, printing up to the last page can of course be performed correctly.

If it is determined in steps 6-1 to 6-2 that page creation is not possible, step 6
-10 enters wait state. This suspends page creation only while one page is being printed.
This prevents unprinted pages from being destroyed by newly created pages.

Note that the CPU 3-3 is set to "L" before printing.
Create a page for the page. This is a measure to absorb the difference between the order of pages created in this embodiment and the order of pages printed. Then, after page creation is completed, printing of the page is started. This "L" indicates the reference value in the condition determination step 6-1, that is, the total number of page buffers in the page buffer 3-4 (and the total number of each management register included in the management register group 3-7).

Figures 7 1 and 2 show a schematic flowchart of the printing procedure.

In step 7-1, the copy part number counter 3-18 is set to 1 and initialized.

In step 7-2, print pointer 3-1
Print management pointer 3 of the print register specified by 4
-9-2, the contents of the separation management pointer 3-8-1 in the separation register specified by the separation read pointer 3-13 are set, and the copy part number counter is set in the part number counter 3-9-3 of this print register. The value of 3-18 is set, and the print flag 3-9-1 of the print register is set to "possible".

In step 7-3, print counter 3-1
Set 5 to 1.

As described above, in steps 7-1 to 7-3, the first side of the page to be printed first (second page) is set in the print register.

In step 7-4, the CPU 3-3 checks the print flag 3-9-1 of the print register indicated by the print pointer 3-14, and if it is "possible", the side corresponding to this print register is printable. If it is determined that there is, printing is performed (see step 7-5 onwards).

In step 7-5, the CPU 3-3 obtains the management register of the page to be printed from the print management register 3-9-2 of the print register indicated by the print pointer 3-14, and sets the page existence flag 3-7- of the management register. Check 1. If the result is "Yes", it is determined that there is a page to be printed, and printing is performed in steps 7-6 and subsequent steps.

In step 7-6, the CPU 3-3 obtains a management register from the print management register 3-9-2 of the print register indicated by the print pointer 3-14, and stores the page buffer indicated by the page buffer pointer 3-7-2 (i.e., page to be printed). Then, the printing hardware 3-5 and printing device 3-6 are appropriately controlled to print one sheet (single-sided). Also, printing itself is done by CPU3-
3, the page creation procedure is executed until printing of one page (single-sided) is completed.

When printing of one sheet (single side) is completed, control is transferred to step 7-7.

In step 7-7, the CPU 3-3 checks whether printing has been performed normally based on signals from the printing device 3-6, etc., and if printing has been performed normally, the process proceeds to step 7-8. Transfer control.

In step 7-8, the CPU 3-3 checks whether the previous print is a sample print generated during printing based on the signal from the printing device 3-6, etc., and if it is not a sample print, the process proceeds to step 7-9.
Transfer control to

In step 7-9, print pointer 3-1
The print flag of the print register indicated by 4 is set to "non".

In step 7-10, the value of the print counter is decremented by one. That is, step 7 mentioned above
-9 and 7-10, the print register corresponding to the side printed in step 7-6 is opened.

In step 7-11, print pointer 3-14
Part number counter 3-9 in the print register indicated by
The value -3 is compared with the value of the copy number register 3-17. If they match, it is determined that printing has been completed for all copies of that page, and control is transferred to step 7-12, which opens the page buffer.

In step 7-12, print pointer 3-14
Print management pointer 3-9- of the print register indicated by
2, the management register of the page that has just been printed is obtained, and the page presence/absence flag 3-7-1 is set to "absent".

In step 7-13, the page number counter 3-
Decrease the value of 11 by 1. Step 7-
The page buffer for which printing has been completed is released by the processes 12 and 7-13, and a new page can be created in the page buffer in the page creation procedure.

In step 7-14, print pointer 3-
Page index 3-9-4 of the print register indicated by 14
Check and if it is even, step 7-15
Transfer control to

In step 7-15, information about the odd-numbered page, which is the reverse side of the even-numbered page that has just been printed, is set in the print register (details will be described later).

In step 7-16, print counter 3-
Increase the value of 15 by 1.

In step 7-17, the copy part number counter 3-18 is set to 1 and initialized.

In step 7-18, the separate read pointer 3
-13, sets the second isolation register counting from the currently indicated isolation register in the page set direction. Since the separate read pointer 3-13 has already indicated an even page in step 5-11 of the initialization procedure shown in FIG.
The separated read pointer 3-
13 will always indicate an even page.

In step 7-19, the separate read pointer 3
The management register indicated by the separation management pointer 3-8-1 (that is, corresponding to the next even-numbered page to be printed) is found in the separation register specified by -13, and the page presence/absence flag 3-7-1 is checked.
If "Yes", the next even-numbered page to be printed has already been created on the page buffer, so this even-numbered page is set in step 7-20 and subsequent steps.

In step 7-20, the separate read pointer 3
-13 and the copy number counter 3-18, the even page information to be printed next is set in the print register.

At step 7-21, the value of the print counter is incremented by 1, corresponding to the page set in the print register at step 7-20.

In step 7-22, print pointer 3-
14 is incremented by 1 and the next print register is set.

In step 7-23, print counter 3-
The value of 15 is checked, and if it is not zero, there are still surfaces to be printed, and the control is returned to step 7-4.

In step 7-4, print pointer 3-1
If the print flag 3-9-1 of the print register indicated by 4 is "non", control is transferred to step 7-32.

In step 7-32, one blank print is performed. Here, "blank printing" means interrupting printing for only the time required to print one page, or printing one completely blank page. Note that during blank printing, paper is not fed even if the page indicated by the print pointer 3-14 is an even numbered page. Furthermore, the CPU 3-3 executes the page creation procedure during blank printing as well as during printing in step 7-6.

At step 7-5, if there is no page to be printed, control is transferred to step 7-28.

In step 7-28, one blank print is performed.

In step 7-29, the CPU 3-3 reads the duplex spacing M from the duplex spacing register 3-16, and reads the Mth duplex spacing M in the printing direction from the print register indicated by the print pointer 3-14 (i.e., the even-numbered side currently blankly printed). Set the print flag in the print register for the back side) to "non".

In the double-sided printing according to this embodiment, even-numbered pages are printed before odd-numbered pages are printed. Therefore, only even-numbered pages are left blank due to reasons such as not being able to create the page in time.

In step 7-30, print pointer 3-14
The contents of the print register indicated by (print flag 3-9-
1. Copy the print management pointer 3-9-2 and copy number counter 3-9-3) to the second print register (that is, the even-numbered side to be printed next) in the printing direction. This means that even-numbered pages that could not be printed because the pages were "null" will be printed during the next even-numbered side printing.

In step 7-31, print pointer 3-
Print flag 3-9-1 of the print register indicated by 14
Set to "Non".

In step 7-30, page information is set,
Since the print register is opened in step 7-31, the value of print counter 3-15 does not change in steps 7-28 to 7-31.

If printing has ended abnormally, control is transferred to step 7-29 (step 7-7).

If the previous print is a sample print produced during printing, control is transferred to step 7-29 (step 7-8).

Copy part number of the printed side (print pointer 3-1
Part number counter 3- in the print register indicated by 4
If the value of copy number register 3-17 is smaller than the value of copy number register 3-17, the predetermined number of copies of that page have not been printed yet, and control is transferred to step 7-24 (step 7-11). ).

In step 7-24, print pointer 3-14
Check the page index 3-9-4 of the print register indicated by , and if it is "even", control is passed to step 7-2
Move to 5.

In step 7-25, step 7-1
Using the same procedure as step 5, set the odd-numbered pages on the back side that you just printed.

In step 7-26, print counter 3-
Increase the value of 15 by 1.

In step 7-27, the value obtained by adding 1 to the copy number of the printed side is added to the copy number counter 3-18.
Set to .

In steps 7-14 and 7-24, if the printed pages are odd pages (i.e.
If it is determined that the page index 3-9-4 of the print register indicated by the print pointer 3-14 is "odd", control is transferred to step 2-22.

Further, in step 7-19, if it is determined that the next even-numbered page to be printed is "none", control is transferred to step 7-22. This means that since the next even page has not yet been created, that page is not set in the corresponding print register.

In step 7-23, print counter 3-
If it is determined that the value of 15 is zero, there are no more pages to be printed on the print register group 3-9, so printing is terminated.

FIG. 8 shows a detailed flowchart of the one-sheet printing procedure in step 7-6 shown in FIG.
Here, paper feeding is performed only for printing even-numbered pages.

In step 8-1, the print management pointer 3-9-2 of the print register indicated by the print pointer 3-14 is
The management register of the page to be printed is read from .

In step 8-2, the page buffer pointer 3-7 of the management register obtained in step 8-1 is
The page buffer indicated by -2 is instructed to the printing hardware 3-5.

In step 8-3, the CPU 3-3 issues a print command to the printing hardware 3-5 and printing device 3-6.

In step 8-4, printing hardware 3
-5 prints the print information (for one page) on the page buffer instructed in step 8-2 to the printing device 3-6.
The transferred print information is then printed by the printing device 3-6.

Printing hardware 3-5 and printing device 3-6
operates autonomously while printing one page, so
The CPU 3-3 executes the page creation procedure for this one page during printing, and returns to the printing procedure in response to a one-page printing end signal from the printing device 3-6.

Figure 9 shows steps 7-15 and 7-25 shown in Figure 7 (the contents of both steps are the same).
This is a detailed flowchart showing in detail the procedure for setting odd page information to the print register.

In step 9-1, double-sided spacing register 3-1
Obtain the distance M between both sides from 6.

In step 9-2, the M-th print register (the register corresponding to the odd-numbered page on the back side of the even-numbered page just printed) is found as counted in the printing direction from the position indicated by the print pointer 3-14.

In step 9-3, the separation read pointer 3-
The contents of the separation register one before the separation register indicated by 13 (that is, the position of the management register corresponding to the odd-numbered page on the back side of the even-numbered page that was just printed) are printed in the print register obtained in step 9-2. Set pointer 3-9-2.

In step 9-4, the part number counter 3-9- in the print register indicated by the print pointer 3-14 is
The value 3 is set in the part number counter 3-9-3 in the Mth print register.

In step 9-5, the print flag 3-9-1 in the Mth print register is set to "possible".

FIG. 10 shows step 7-20 shown in FIG.
(A detailed flowchart of the procedure for setting even page information to the print register is shown.)

In step 10-1, print pointer 3-14
Find the second print register counting in the printing direction from the position indicated by (that is, the register corresponding to the even-numbered side (first side) to be printed next to the even-numbered page just printed).

In step 10-2, the separate read pointer 3
The content of the separation register indicated by -13 (that is, the position of the management register of the next page to be printed) is set to the print management pointer 3-9-2 in the second print register obtained earlier.

In step 10-3, copy part number counter 3
The value -18 is set in the part number counter 3-9-3 of the second print register.

In step 10-4, the print flag 3-9-1 in the second print register is set to "possible".

FIG. 11 shows step 7-28 shown in FIG.
and step 7-32 (blank print execution procedure)
A detailed flowchart is shown.

In step 11-1, the CPU 3-3 instructs the printing hardware 3-5 and printing device 3-6 to print a blank page. Then, in step 11-2, a blank page is printed and
The CPU 3-3 executes the page creation procedure.

In the printing procedure of this embodiment described above, if printing on one side of an even page is completed normally, the print register corresponding to that side is released (see step 7-9 and step 7-10). , the odd-numbered page corresponding to the reverse side of the side just printed (see steps 7-15, 7-16 and steps 7-25, 7-26), and the even-numbered page after the printed side (steps 7-20, 7-26). 21) in the print register.

On the other hand, after printing on the first side of an odd-numbered page, the print register is released, but the print register is not set.

The odd-numbered page setting procedure shown in steps 7-15 and 7-25 ensures that the odd-numbered page on the reverse side is printed on the Mth sheet after printing an even-numbered page, and the The page correspondence will be correct.

The procedure of steps 7-20 also ensures that even pages are printed in the correct page order. Therefore, through the page setting procedures of steps 7-15/7-25 and steps 7-20, pages are set on the print register group 3-9 in the page order required for double-sided printing.

FIGS. 12-124 are schematic diagrams showing the state of double-sided printing according to this embodiment. Here, the rings equally divided radially by broken lines indicate the ring-shaped print register group 3-9, and the arrows indicate the print pointer 3-143-1.
4, the center of the ring represents a print counter, respectively. Also, print pointer 3-143-1
The traveling direction (printing direction) of 4 is clockwise in this figure. Then, use the arrow to move the print pointer 3
-14 represents the print register. Further, the numbers in the ring-shaped print register group 3-9 represent the page numbers set in the print registers, and the numbers written in the center circle of the ring represent the value of the print counter 3-15.

12 shows the state between steps 7-3 and 7-4 in FIG. 7, that is, immediately after the first page (second page) is set in the print register, and FIGS. 2 to 23 show the state between steps 7-3 and 7-4 in FIG. 24 shows the state immediately before printing is completed. Also, if the number in the ring is crossed out with a reverse slash (\), this means that the page was printed immediately before and the print register was opened. Furthermore, the print register in which the page number that is not erased with (\) is written has print flag 3-9-.
1 is “possible” and other print registers are “not”
It represents that.

In Figures 12-24, the double-sided spacing M = 5, the number of registers in print register group 3-9 is 10, the number of copies is 1, the total number of pages is 18, and all pages are normal prints (not sample prints), so everything is normal. The example is shown when printed on . Each case will be explained in detail below.

FIG. 12 shows the state immediately after the second page to be printed for the first time has been set.

In Figure 12, the second page is printed (see step 7-6), its print register is opened (see steps 7-9 and 7-10), and the first page, which is the back side of the second page, is printed (see step 7-6). (see 7-15 and 7-16) The print pointer 3-
The state is shown in which the Mth page and the second page are set from position 9 (steps 7-4 to 7-21 are passed).

FIG. 12 shows the state immediately after printing one blank page (see step 7-33) after printing the second page.

In this embodiment, odd pages are printed for the first time when the sheet, on which even pages have been printed on the first side, has gone around the conveyance loop.

Therefore, for a while after printing starts, there is no sheet between even-numbered pages on which odd-numbered pages should be printed. Further, in double-sided printing according to the present embodiment, paper is fed for printing an even number of pages, and the paper feeding interval is twice that of the one-sided printing (that is, the timing for every other page). Therefore, in the initial stage of printing, it is necessary to alternately repeat printing of even-numbered pages and blank printing. FIGS. 1-5 show this transient state at the initial stage of printing.

FIG. 12 7 shows that the first page, which is an odd page, has been printed (see step 7-6) and its print register has been released (steps 7-9 and 7-1).
(see steps 7-4 to 7-7).
14 and immediately before step 7-22).

12 to 17 show a steady state in double-sided printing, in which even-numbered pages and odd-numbered pages are printed alternately. At this time, the value of the print counter becomes 4 and 3 alternately (i.e., 3 → 4 after printing even numbered pages, and 4 → 3 after printing odd numbered pages).
).

FIGS. 18-23 show transitional conditions at the end of printing.

Figure 12-18 shows that after printing the last 18th page (see step 7-6) and opening the register (see steps 7-9 and 7-10),
Set page 17 in the print register (Step 7-
15 and 7-16). Here, page 18 is the last page, and step 7
-19's judgment is that the next page will be "nothing", so
The 20th page is never set.

From FIG. 12 onwards, paper feeding is not performed, and printing of odd-numbered pages and blank printing are performed alternately.

Figure 12 23 shows the last odd page, the 17th page.
This shows a state in which the value of the print counter 3-15 becomes zero after printing the page (that is, the back side of the 18th page, which is the last page), and the printing ends 12-24. As described in step 6-12 of the page creation procedure, the final page created on the page buffer is always an even page, regardless of whether the final page of data is an odd or even number.

Next, the number of print registers required in the print register group 3-9 will be explained.

First, in the print register group 3-9, the number of print registers must be even in order to ensure that the even page group and the odd page group are separated.

FIG. 13 is a schematic diagram showing the state of the print register and print pointer 3-14 during the printing process, and shows the case where the double-sided spacing M=7 and the number of print registers=10. In this figure, as in Figure 12, the print register group 3 is divided into radially equally divided rings.
-9 and arrow indicates print pointer 3-14
represents. Further, the numbers within each section of the ring represent the page number set in each print register. Furthermore, when the page number is crossed out with a reverse slash (\), it indicates that the print register for that page has just been released. Among the print registers, the print flag 3-9-1 of the print register with a page number that has not been erased by the reverse slash is "OK", and all others are "NO". In order to distinguish between even-numbered pages and odd-numbered pages, only even-numbered page numbers are enclosed in "key brackets" ([,]).

Direction of movement of print pointer 3-14 (printing direction)
is clockwise. Further, the arrows shown outside the ring indicate the minimum range of print registers required at each point in time. Furthermore, "M-1", "M+1", "M", "M-1" shown on the outer periphery of the ring
Each symbol indicates the number of print registers.

FIG. 13 shows a state in which the lth page (l is an even number) is being printed. At this time, the pages existing on the print register are the (l-th) page in addition to the l-th page.
M) page, the (l-M+2) page, ..., the (l-3)th page, which are odd-numbered pages, and the first, third, ..., M-2th pages counting from page l in the printing direction, respectively. It is in the second place. Therefore, the number of print registers required in this case is (M-1).

FIG. 13 2 shows that after printing the lth page,
+2) The second (l-1)th page is set in the Mth print register when counting the pages in the printing direction. At this time, the unprinted odd pages that need to be placed on the print register are
M) page, (l-M+2)th page, ..., (l-1)th page. Since these odd-numbered pages are set every other page on the print register, the number of print registers needs to be (M+1) in order for them to exist on the print register at the same time.

FIG. 13 shows a state in which the kth page (k is an odd number) is being printed. At this time, the pages that should exist on the print register are the k-th page, the (k+2)-th page, . . . , the odd-numbered pages (k+M-1)-th page, and the (k+M+2)-th page. Therefore, in this case, the number of print registers need only be M or more.

FIG. 13 shows the state after printing the kth page. Here, after opening the print register for the kth page, there are the (k+2)th page, the (k+4)th page, ..., the (k+M-1)th page, an odd numbered page, and the (k+M+2)th page, so it is necessary to The number of print registers to be used is M.

As is clear from the above explanation, the number of print registers in print register group 3-9 is the maximum distance between both sides.
For M _nax (odd number), it is sufficient if it is an even number of M _nax +1 or more.

Next, the number of page buffers required in the page buffer 3-4 will be explained using FIG. 13.

As shown in FIG. 13, while the lth page (l is an even number) is being printed, the (lth
-M) page, (l-M-2) page, ..., odd numbered page (l-3) page (total (M-1)/
2 pages) and the lth page (M+1)/2
The page is set, and it is sufficient that this many pages exist on the page buffer.

As shown in FIG. 13 2, after printing the lth page, the (l+2)th page and the (l−1)th page
After setting the pages, the (l-M)th page, the (l-M-2)th page, ..., the odd numbered pages (l-1)th page (total (M+1)/2) and the (l+1)th page.
2) A total of (M+1)/2+1 pages is set on the print register. Here, for the lth page, both the print register and the page buffer have just been opened, and at this point, a new page has not yet been created on the page buffer where the lth page existed. Further, when the (l+2)th page (even number) exists, the (l+1)th page (odd number) also exists on the page buffer. Therefore, at the time shown in FIG. 13, a page buffer of (M+1)/2+3 pages is required.

As shown in FIG. 13, during the printing of the kth page (k is an odd number), the kth, (k+2)th, ..., (k+M-)th pages are displayed on the print register.
1) The sum of the odd numbered pages (total (M+1)/2 pages) and the (k+M+2)th page (M+
1)/2+1 pages exist. Also, as in FIG. 13 2, the (k+M+
1) Since there are pages, the number of page buffers required is (M+1)/2+2.

As shown in Fig. 13 4, after printing the kth page, the kth page is not released (Fig. 13 3
), and no new page has been created yet in the page buffer where the k-th page existed, so the number of page buffers is (M+1)/2
It becomes +2.

As is clear from the above description, the required minimum number of page buffers is (M _nax +1)/2+3 for the maximum double-sided spacing M _nax .

Next, the required minimum number of separate register groups 3-8 will be explained.

First, since a page set in a page buffer is always set in a separate register, the number of separate registers must be greater than the number of page buffers.

Now, let the number of page buffers be n (n≧(M+
1)/2+3), the required number of separate registers will be considered below.

The required number of separate registers is consecutive pages from the oldest page on the page buffer to the newest page on the page buffer (printed pages also remain on the separate register). In other words, for n pages of the page buffer, the oldest page on the page buffer (even-numbered pages are printed before odd-numbered pages, so the oldest page is always an odd-numbered page)
This is the sum of the number of subsequent even-numbered pages that have been printed and whose page buffers have been released.

In the case shown in FIGS. 1 and 2, the even-numbered pages before the l-th page have been released, and the oldest page is the (l-M)-th page (odd number), so
The number of even pages between the (l-M)th page and the (l-1)th page is (M-1)/2. Therefore, the number of separate registers required is n+
(M-1)/2. To explain this further,
The result is as shown below.

However, 〓 indicates a page that has already been printed but has been removed from the page buffer.

Even numbered pages before page l-2 All pages before l-M+1 page (odd) represents an odd numbered page.

Similarly, the cases of FIGS. 3 and 4 in FIG. 13 are expressed as follows:
The result is as shown below.

Therefore, the required minimum number of separate registers is still n+(M-1)/2.

Next, a procedure for dealing with the case where incorrect paper feeding occurs will be explained.

When incorrect paper feeding is detected in the printing device 3-6, the printing device 3-6 reports the occurrence of the incorrect paper feeding to the CPU.
3-3, and dispose of the incorrectly fed sheets. The reason for this is that normal printing cannot be expected from incorrectly fed sheets, and it is not desirable for sheets with abnormal printing to mix with normally printed sheets. That's because there isn't. Moreover, incorrectly fed sheets are likely to cause jams, and it is particularly undesirable to pass them through a complicated conveyance element such as a reversing mechanism.

A sheet that has been incorrectly fed in the paper feed mechanism 1-1 (see FIG. 1) is conveyed to the post-fixing conveyance path 1-7 via the pre-transfer conveyance path 1-2, and then transferred to the pre-reversal branching mechanism 1.
-8. In this pre-reversal branching mechanism 1-8, unlike the case of normal paper feeding, the pre-stacker transport path 1-1
A branch to 2 is taken. Front stacker branching mechanism 1-
At step 14, the incorrectly fed sheet is branched and ejected to the auxiliary tray 1-15.

As described above, the incorrectly fed sheet is discarded without passing through the conveyance loop.

Therefore, in the event of incorrect paper feeding, even pages that should have been printed on both sides of the sheet,
Odd numbered pages must be printed correctly on separate sheets. Hereinafter, the processing procedure when incorrect paper feeding occurs will be explained with reference to the drawings.

FIGS. 14 to 24 are schematic diagrams of the double-sided printing shown in FIG. 12 in the case where incorrect paper feeding occurs during the process. Note that, as described above, in this embodiment, paper feeding is performed only when printing even-numbered pages, so it goes without saying that incorrect paper feeding occurs when printing even-numbered pages.

1-5 of FIG. 14 are completely the same as FIGS. 1-5 of FIG. 12, so the explanation will be omitted.

FIG. 14 shows the situation when incorrect paper feeding occurs during printing of the sixth page.

If incorrect paper feeding occurs during printing at step 7-6 shown in FIG. 7, the process branches to step 7-29 based on the determination at step 7-7. In step 7-29, the print register for the odd numbered page that was scheduled to be printed on the second side of the incorrectly fed sheet is released. As a result, blank printing is performed at the timing when the odd-numbered page was scheduled to be printed (see FIG. 14). This corresponds to the fact that the sheet that was scheduled to be printed here is discarded and does not reach the transfer position 1-4.

Next, in step 7-30, the even-numbered pages that could not be printed due to incorrect paper feeding are set in the print register for the next even-numbered side. As a result, even-numbered pages that could not be printed properly due to incorrect paper feeding are reprinted the next time paper is fed (see FIG. 14, 8).

In step 7-31, the print register for even-numbered pages that could not be printed normally due to incorrect paper feeding is released.

Also, step 7-7, steps 7-29 to 7
If the path -31 is passed, the number of pages set on the print register does not change, so the value of the print counter 3-15 does not change.

The basic algorithm of the printing procedure according to this embodiment is that only after a certain even page has been printed successfully, set the odd page to be printed on the reverse side and the even page to be printed next. . Therefore, even if incorrect paper feeding continues for a long time,
This does not affect the page order of the sheets loaded on the stacker in any way.

Furthermore, as is clear from the above description, even if incorrect paper feeding occurs, printing of that one sheet (two pages) is only delayed, and the reduction in throughput can be kept to a minimum. (Figure 14 and 1
(See figure 2 for comparison). In other words, due to the incorrect paper feeding caused by FIG. 14 6, printing is delayed by two pages (that is, one sheet) compared to the case in FIG. 12, and even in FIG. 14 24, page 17 is still unprinted. It is becoming.

[Effect] As explained above, according to the present invention, even if incorrect paper feeding occurs, it is possible to maintain a predetermined page relationship without affecting the recorded medium in any way. Moreover, double-sided recording can be easily performed.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a sheet conveyance system of a duplex printing apparatus that is an embodiment of the present invention, and FIG. 2 shows the conveyance system shown in FIG. 1 and the state of sheets flowing thereon. 3 is a schematic diagram of an offline printing system to which the present invention is applied, FIG. 4 1 to 3 are diagrams showing the structure of registers etc. shown in FIG. 3, and FIG. 5 is a flowchart showing the initialization procedure. Chart, Figure 6 is a flowchart showing the page creation procedure, Figure 7 is 1 and 2.
8 is a schematic flowchart showing the printing procedure, FIG. 8 is a detailed flowchart showing the printing procedure for one sheet, and FIG.
The figure is a detailed flowchart showing the procedure for setting odd-numbered pages, FIG. 10 is a detailed flowchart showing the procedure for setting even-numbered pages, FIG. 11 is a detailed flowchart showing the procedure for executing blank print, and FIG.
1 to 24 and FIGS. 13 to 4 are schematic diagrams showing the situation during double-sided printing, respectively, and FIGS. 14 to 24 are schematic diagrams each showing the response procedure in the case where incorrect paper feeding occurs. 1-1...Paper feeding section, 1-2...Pre-transfer conveyance path,
1-3...Drum, 1-4...Transfer charger, 1-
5... Pre-fixing conveyance path, 1-6... Fixing device, 1-7
... Conveyance path after fixing, 1-8 ... Pre-reversal branching mechanism,
1-9... Conveyance path before reversal, 1-10... Reversing mechanism, 1-11... Conveyance path after reversal, 1-12... Conveyance path before stacker, 1-13... Stacker, 1-1
4... Pre-stacker branching mechanism, 1-15... Auxiliary tray, 2-1... Sheet transport loop, 2-2-
1-2-2-5...sheets being conveyed, 3-
1...Magnetic tape (MT), 3-2...Magnetic information conversion device, 3-3...Central processing unit (CPU), 3
-4... Page buffer, 3-5... Printing hardware, 3-6... Printing device, 3-7... Management register group, 3-8... Separation register group, 3-9...
...Print register group, 3-10...Page pointer, 3-11...Page number counter, 3-12...
... Separation set pointer, 3-13 ... Separation read pointer, 3-14 ... Print pointer, 3-15
...Print counter, 3-16...Double-sided spacing register, 3-17...Copy number register, 3-18
... Copy part number counter, 3-7-1 ... Page existence flag, 3-7-2 ... Page buffer pointer, 3-8-1 ... Separation management pointer, 3-9
-1...Print flag (possible/not possible), 3-9-2...
Print management pointer, 3-9-3... Part number counter, 3-9-4... Page index (even/odd), 5-
1~5-14, 6-1~6-12, 7-1~7-
32,8-1~8-4,9-1~9-5,10-
1 to 10-4, 11-1 to 11-2...control steps.

Claims (1)

[Claims] 1. A storage means for storing a plurality of pages of recording information, after recording the first side of the 1st to Mth recording sheets (M is a natural number and a constant value), M+
double-sided recording means for alternately recording on the first side of the i-th recording sheet (i is a natural number that increases sequentially) and recording on the second side of the i-th recording sheet; recording from the storage means; Means for reading out information page by page and supplying the information to the double-sided recording means, wherein the information is stored in the storage means in a predetermined order so that the recorded matter recorded and output by the double-sided recording means is in the correct page order. reading means for reading recorded information on a plurality of pages and supplying the recorded information to the double-sided recording means; a paper feeding means for feeding the recording sheet to the double-sided recording means; feeding of the recording sheet by the paper feeding means is normal; If not, the reading means records page by page so that the recording information to be recorded on the recording sheet that was not fed normally is recorded on the recording sheet that is newly fed by the paper feeding means. A recording device comprising: control means for changing the order of reading information.