JPS6073635A - Recorder - Google Patents

Abstract

PURPOSE:To perform both-surface recording efficiently and easily even when paper is fed illegally by providing a means which carries out the recording in prescribed page relation even in case of illegal paper feeding. CONSTITUTION:Pieces of page information are generated continuously like the 1st page, the 2nd page - in a page buffer 3-4 on the basis of information read out of a magnetic tape 3-1. A separation register group 3-8 separate said pages generated in order in the page buffer 3-4 and a control register group 3-7 into even-numered pages and odd-numbered pages. A print register group 3-9 adjusts the order of pages to be printed according to a specific order pattern which is requested for both-surface printing. For the purpose of said adjustment of the print order, the print register group 3-9 simulates sheet paper pages on a conveyor loop in both-surface printing.

Description

Detailed Description of the Invention [Technical Field 1] The present invention relates to a recording device configured to perform double-sided recording.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 recording devices that print or copy on sheet-like recording media, imperfect paper feeding such as electric feeding, skew feeding, and leading edge lag may occur during paper feeding (hereinafter, these are collectively referred to as incorrect feeding). paper). Recording is not performed in the correct position on a sheet-like recording medium that has been improperly fed, and furthermore, this is a cause of paper 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. or,
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 replace the page corresponding to the discarded sheet-like recording medium. Re-recording was required. 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 low throughput.

[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 that can perform double-sided recording, including a control means that performs recording with a predetermined page relationship even in the case of incorrect paper feeding. The present invention will be described in detail with reference to the drawings.

FIG. 1 shows a sheet conveying system of a double-sided printing apparatus which is an embodiment of the present invention. In this figure, 1-1 is a paper feed unit, 1-
2 a pre-transfer conveyance path; 1-3 a drum for forming a toner image to be transferred onto the surface of a sheet using known electrophotographic technology;
1-4 is a transfer charger that transfers the toner image on the drum 1-3 onto a sheet of paper, 1-5 is a conveyance path before fixing, and 1-8 is a transfer charger that transfers the toner image transferred onto the sheet of paper by heat and pressure. A fixing device for fixing, 1-7 is a post-fixing conveyance path, 1-8 is a pre-reversal branching mechanism that branches a sheet conveyance path, 1-9 is a pre-reversal conveyance path, 1-10 is a front and back side of a sheet. 1-11 is a reversing support path, 1-12 is a conveyance path in front of the stacker, 1-13 is a stacker,
1-14 is the stacker front branching mechanism, 1-15 is the auxiliary)
It is 1/I.

During double-sided printing, sheets fed S 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 known electrophotographic technology is transferred onto a sheet of paper by corona discharge in the transfer charger 1-4, and then,
The fixing device via the pre-fixing conveyance path 1-5! -8. After the image on the first side has been fixed in the fixing device 1-6, the paper is conveyed via the post-fixing conveyance path 1-7, passes through the pre-reversal branching mechanism 1-8 and the pre-reverse conveyance path 1-8, and then is transferred to the reversing mechanism. 1-
Sent to 10.

The single-sided printed sheet that has been reversed in the reversing mechanism 1-1O is sent to the pre-transfer transport path via the reversing back transport path 1-11. -2, the drum 1-3 and the transfer charger 1-
4, image transfer on the back side (second side) is performed in the same way as in the previous one-sided printing. Thereafter, it is sent to the fixing device 18 via the pre-fixing conveyance path 1-5, where the image on the second side is fixed. At this point, double-sided printing is complete.

The double-sided printed sheet is transferred from the post-fixing conveyance path 1-7 to the pre-reversal branching mechanism 1-8. Conveyance path in front of stacker! - It is loaded onto the stacker 1-13 via the machine 2 and the stacker front branching mechanism 1-14.

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 as when printing on one side (that is, the number of pages that can be printed within a unit time), it is necessary to pass the sheets through the drum ta at the same intervals as when printing on one side. . 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 1-1O
When the sheet that has been reversed flows from the post-reversal conveyance path 1-11 to the pre-transfer conveyance path 1-2, there is a gap between the unprinted sheet immediately after being sent from the paper feed section 1-1 and the unprinted sheet. Configure it to be in the middle.

By operating in this way, the pre-transfer conveyance path 1-2
From drum 1-3. Transfer charger l-4, pre-fixing conveyance path l
-5. Fixing device 1-8. In the conveyance path from the post-fixing conveyance path 1-79 to the pre-reversal branching mechanism 1-8, sheets that have already been printed on the back side and sheets that have been printed only on the first side alternately flow. .

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

In this case, the pre-transfer conveyance path l-2, the drum 1-3. Pre-fixing conveyance path l-5. Fixing device 1-8. Fixing nip transport path 1-71 Pre-reversal branching mechanism 1-81 Anti-reverse pre-feeding path 1-91 Reversing mechanism 1
-10. The length of one transport path loop consisting of the post-reversal transport path 1-11 must be an odd number 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 sheets fed from the paper feed section 1-1,
A problem arises in that the sheet from the post-reversal conveyance path 1-11 overlaps on the pre-transfer conveyance path 1-2. In other words, after the first side of a certain sheet arrives at the position of drum I-3, the second side of that sheet returns to the position of drum 1-3 again at the odd-numbered side. It is.

In this embodiment described above, the spacing between both sides of the sheet (i.e.,
A sheet whose first side has been printed is returned to drum l-3.
The number of sheets to return to and print on the second side corresponds to after passing through drums 1-3)
Let be X. Therefore, for example, in the case of M-5, after printing the first side, a new 4
You will have to print one sheet.

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 properly hold the pages.

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, in order to properly arrange pages during double-sided printing, it is necessary to print the later page first among the pages to be printed on both sides of a certain sheet. If printing starts from the first page, even-numbered pages will be printed before odd-numbered pages.

FIG. 2 is a schematic diagram showing the state of the conveyance system shown in FIG. 1 and the sheets carried thereon in the case where the distance between both sides is 5. In this figure, the reversing mechanism 1-10 is schematically represented as "a section through which a sheet is reversed". 2-1 is a sheet transport loop;
-2-1 to 2-2-5 are sheets being conveyed.

Here, the numbers without parentheses written on both sides of each sheet are the page numbers printed or currently being printed on that side, and the numbers in parentheses indicate the page numbers to be printed.

In FIG. 2, unhatched sheets 2-2-2 and 2-2-4 have not yet been reversed, and hatched sheets 2-2-1 and 2-2-3 indicates that it has been reversed. Furthermore, the sheet 2-2-5 that is partially hatched indicates that it 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 under the control of CPυ3-3. Page buffer 3
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; -8 is a separation register group that separates the page information of each page created in I[Next Page Buffer 3-4] into pages printed on the front side and pages printed on the back side of the paper during duplex printing. .

3-8 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 register that was set last among the management register group 3-7; and 3-11 is a page buffer 3. 3-12 is a page number counter indicating the number of currently printable pages created in 4, and 3-12 is a page counter that indicates the number of pages created in 4, and 3-12 is a page that is used when new page information is created in the separate register group 3-8. 3-13 is a separate read pointer that indicates 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 3-16 is a print pointer indicating the register corresponding to the side currently being printed; 3-15 is a print counter indicating the number of registers corresponding to the side to be printed among the print register group 3-8; 3-17 is a double-sided spacing register for registering the double-sided spacing, 3-17 is a copy number register for registering the number of copies (in other words, indicates how many copies of the same page are to be printed consecutively), and 3-18 is a double-sided spacing register for registering the ``same page'' This is a copy number counter that indicates how many copies of a page have been printed.

FIGS. 4(1) to 4(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: (1) Page existence flag 3-7 indicating whether page information of the page indicated by the register exists. -1, ■ Page buffer pointer 3-7- indicating the position on the page buffer occupied by the page indicated by the register
2. Other information necessary to print one page.

The contents of each register included in the separated register group 3-8 (see FIG. 4 (2)) are separated management pointers 3-8- representing the registers in the management register group 3-7 corresponding to the page indicated by the register. It is 1.

The contents of each register included in the print register group 3-9 (see FIG. 4 (3)) are: ■ print flag a-s-i indicating whether or not to print the side indicated by the register; Print management pointer 3-9- indicating a register in the management register group 3-7 having corresponding page information
2. ■ When printing multiple copies of one page in succession, a copy number counter 3-! indicates which copy the side indicated by the register is (that is, the copy number). 3-3, ■ Is the side indicated by the register an even-numbered page (i.e., the side to be printed first) or an odd-numbered page (i.e., the side to be printed first)?
Page index 3-9- that indicates whether the page is printed on the first page)
It is 4.

Note that this index is alternately "even" and "odd" (that is, even numbered pages and odd numbered pages) in each register of the print register group 3-9.

The page buffer 3-4 is divided into a plurality of page buffers each corresponding to one page (Fig.
)reference). Furthermore, each register in the management register group 3-7 has a one-to-one correspondence with each partial buffer of the page buffer, and the page buffer pointer 3-7 has this correspondence.
7-1 (see Figure 4 (1)).

The page buffer 3-4 and the management register group 3-7 store the information necessary to print one page, but it is not necessary to separate these 3-4 and 3-7; It is also possible to place various information in the page buffer. However, if the page buffer cannot be placed in the main memory due to memory capacity limitations, the page buffer, which requires a large amount of space, can be placed on a large-capacity secondary storage medium (such as a magnetic disk). It is also possible to deal with this by placing the management register group on the main memory.

The page information created on the page buffer 3-4 based on the information read from the MT 3-1 includes the first page,
They are created consecutively, such as the second and third pages. However, as in this embodiment, when the sheet of paper is printed on the first side,
In a system in which sheets are alternately printed on the second side, the order of the 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 3-3 shown in FIG. 3 serve as this adjustment means. In other words, the separate 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 second side)
It plays the role of separating the On the other hand, print register group 3-9
serves to adjust the order of pages to be printed in a predetermined sequential pattern required for duplex printing.

In order to adjust the printing order, the print register group 3-8 is connected to a transport loop (2-8 shown in FIG. 2) during double-sided printing.
1) Simulate the above sheet page (both sides). The print register indicated by the print pointer 3-14 indicates the page currently being printed (see page 9 on the sheet 2-2-3 shown in FIG. 2), and the print register indicated by the print pointer 3-14 is displayed. Switching is performed sequentially to correspond to the movement of paper on the conveyance loop.

Then, the order of pages on the print register group 3-8 is set as 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, set the page presence/absence flag 3-7-1 of the management register you are currently focusing on to "None" (Step 5-1)
, then initialize various information in the management registers, and repeat this until initialization is completed for all management registers (
Step 5-3.5-4).

In steps 5-5 to 5-7, all of the print flags 3-9-1 of each register in the print register group 3-8 are set to "r-non", and all part number counters 3-9-3 are set to "r". 1”. Also, page index 3-9-4
is set so that even (even numbered pages) and odd (odd numbered pages) are alternated correctly.

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

In step 5-9, the page number counter 3-11 and print counter 3-15 are set to zero.

In step 5-10, among the registers in the separated register group 3-7, the register that should be set first in creating the print information for the first page is set in the separated set pointer 3-12.

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

In step 5-12, among the registers in the print register group 3-9, the register corresponding to the side to be printed on the sheet first is set in the print pointer 3-14 as an initial value. This register must be an even page register (ie, page index 3-9-4 is "even").

In step 5-13, the double-sided spacing determined by the size of the sheet is set in the double-sided spacing register 3-18.

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

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

FIG. 6 is a flowchart showing the procedure for creating a page.

In condition determination steps 6-1 and 6-2, new pages are not created in the page buffer for 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, CPt13-3
reads the information on the IT 3-1 (via the device 3-2) (step 6-4), analyzes this and sets the page buffer pointer 3-7-2 (page pointer 3) in the management register.
-10) creates page information in the remaining page buffer. 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 9 "present".

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

Furthermore, in step 8-13, the page pointer 3-1
The management register indicated by 0 is set in the separate register indicated by the separate set pointer 3-12. This means that the currently created page is registered in the separate register group 3-8.

In step 8-7, the separate set pointer is updated.

In steps 8-8 and 8-9, a management register for creating the next page information is searched. That is, while advancing the page pointer 3-10 one by one, the page presence/absence flag 3-7-1 of the management register is checked, and this is repeated until the first management register whose page presence/absence flag is "none" is found. After this, control returns to step 6-1 again.

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

0 In step 6-11, it is checked whether the current page is an odd numbered page or an even numbered page from the relative positions of the separated set pointer and the separated read pointer, and if it is an odd numbered page, page creation is finished. . 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.

Furthermore, if the relative position is an odd number, the current page is an even number.

In step 6-12, completely blank page information is created in the page buffer indicated by page pointer 3-1O.

The process of step 6-12 means that when the print information of MT 3-1 ends at an odd page (k page), a dummy page is created on the next even page (k+1 page).

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 <k10t pages) to be printed in advance, the sheet on which page k + 1 page should be printed will not be fed. That is, although a toner image is formed on the drum 1-3 for the second page, since there is no paper to which to be transferred, the page is not printed as a result.

Judgment in step 6-11 and step 8-1
By the processing in step 2, even if the print information on the MT 3-1 ends with an odd numbered page, the above-described page omission can be prevented by creating a dummy even numbered page. 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, the process enters a waiting state in step 8-10. This suspends page creation only while one page is being printed, thereby preventing unprinted pages from being destroyed by newly created pages.

Note that, prior to printing, the CPU 3-3 creates an "L" 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 rlJ indicates the reference value in the condition determination step 8-1, 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).

FIGS. 7(1) and 7(2) show a schematic flowchart of the printing procedure.

Step? -1, copy number counter 3-18
Set 1 to 1 to initialize.

Step? -2, the content of the separate management pointer 3-8-1 in the separate register specified by the separate read pointer 3-13 for the print management pointer 3-9-2 of the print register specified by the print pointer 3-14. and set the part number counter 3-8- of this print register.
The value of the copy number counter 3-18 is set to 3, and the print flag 3-Ll of the print register is set to "possible".

In step 7-3, 1 is set in the print counter 3-15.

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. It is determined that there is, and printing is performed (see step 7-5 and subsequent steps).

In step 7-5, the CPU 3-3 selects the print management register 3-9 of the print register indicated by the print pointer 3-14.
The management register of the page to be printed is set from '-2, and the page presence/absence flag 3-7-1 of the management register is checked.

If the result is "Yes", it is determined that there are four pages to be printed, and printing is performed in steps 7-8 and subsequent steps.

In step 7-6, the CPU 3-3 selects the print management register 3-9 of the print register indicated by the print pointer 3-14.
-2 to the management register and obtain the page buffer (that is, the page to be printed) indicated by the page buffer pointer 3-7-2. And printing hardware 3-5
The CPU 3-3 controls the printing device 3-6 appropriately to print one page (single-sided).
The page creation procedure is executed until the printing of one page (single-sided) is completed.

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

In step 7-7, the CPU 3-3
Based on signals from .theta., etc., it is checked whether printing has been performed normally or not, and if printing has been performed normally, control is transferred to step 7-8.

Step? -8, the CPU 3-3 prints the printing device 3-
Based on signals from 8 and the like, it is checked whether the previous printing is a sample print that occurred during printing, and if it is not a sample print, control is transferred to step 7-8.

In step 7-9, the print flag of the print register indicated by the print pointer 3-14 is set to "non".

In step 7-10, the value of the print counter is decremented by one. That is, steps 7-8 and ? −
At step 10, the print register corresponding to the side printed at step 7-8 is opened.

In step 7-11, the value of part number counter 3-9-3 in the print register indicated by print pointer 3-14.

The value of copy number register 3-17 is compared. If they match, it is determined that printing has been completed for all copies of that page, and step 7-12
Control is transferred to freeing the page buffer.

In step 7-12, the print management pointer 3-9-2 of the print register indicated by the print pointer 3-14 is set to the management register of the page that has just been printed, and the page existence flag 3-7-1 is set to [fg J Set to .

In step 7-13, the value of page number counter 3-11 is decremented by 1. Steps 7-12 and ? described above. −
The page buffer for which printing has been completed is released by the process in step 13, and a new page can be created in that page buffer in the page creation procedure.

Step? -14, check the page index 3-9-4 of the print register indicated by the print pointer 3-14, and check if it is "even".
If so, control is transferred to step 7-15.

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

In step 7-18, the value of print counter 3-15 is incremented by one.

In step 7-17, copy number counter 3-1
Set 8 to 1 and initialize it.

In step 7-18, the second separation register counting from the separation register currently being read in the page set direction is set for separation read pointer 3-13. Since the separate read pointer 3-13 has already indicated an even page in step 5-11 of the initialization procedure shown in FIG.
By the procedure shown in step 7-18, the separate read pointer 3-13 always indicates an even page.

In step 7-18, the separation management pointer 3-8 is read in the separation register specified by the separation read pointer 3-13.
-1 (that is, corresponding to the even page to be printed next), and set the page presence/absence flag 3-
Check 7-1. 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, information on the next even-numbered page to be printed is set in the print register based on the one-separation read pointer 3-13 and the copy number counter 3-18.

The step 2 saver 21 increments the value of the print counter by 1 corresponding to the page set in the print 8 register in step 7-20.

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

In step 7-23, the value of the print counter 3-15 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, the print flag 3-! of the print register indicated by the print pointer 3-14! If 3-1 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, even if the page indicated by the print pointer 3-14 is an even page, paper feeding is not performed, and the CPU 3-14 is not fed.
3 executes the page creation procedure during blank printing as well as during printing in step 7-8.

Step? -5, if the page to be printed is "none", control is transferred to step 7-28.

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

In step 7-28, the CPU 3-3 reads the double-sided spacing X from the double-sided spacing register 3-16, and reads the double-sided spacing Set the print flag in the print register for the back side) to "Non".
Set to .

In the double-sided printing according to this embodiment, printing of even-numbered pages precedes printing of odd-numbered pages. 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, the contents of the print register indicated by the print pointer 3-14 (print flag 3-9-1, print management pointer 3-9-21 copy number counter 3-9-3) are
Copy to the second print register (that is, the next even-numbered side to be printed) counting in the printing direction. This means that the page is
This means that even-numbered pages that could not be printed due to "No" will be printed during the next even-numbered copy printing.

In step 7-31, the print flag 3-9-1 of the print register indicated by the print pointer 3-14 is set to "non".

Since the page information is set in step 7-30 and the print register is released in step 7-31, the value of the print counter 3-15 is set in steps 7-28 to 7-31.
There is no change in this.

Step control if printing ends abnormally? -28
(Step?-7).

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

If the copy number of the printed side (the value of the copy number counter 3-9-3 in the print register indicated by the print pointer 3-14) is smaller than the value of the copy number register 3-17,
The page has not finished printing the predetermined number of copies, so the control step? 1 to move to -24 (step?-11).

Step? At step -24, the page index 3-8-4 of the print register indicated by the print pointer 3-14 is checked, and if it is "even", control is passed to step 7-25.

In step 7-25, the odd-numbered pages on the back side that have just been printed are set using the same procedure as step 7-15.

In step 7-26, the value of print counter 3-15 is incremented by one.

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

In steps 7-14 and 7-24, if the printed page is an odd numbered page (i.e., the print pointer
The page index 3-8-4 of the print register indicated by -14 is "
If it is determined that the
Transfer control to

More steps? -18, if it is determined that the next even-numbered page to be printed is "none", then step 7-
This means that since the next even page 2 has not yet been created, the page is not set in the corresponding print register.

Step? -23, if it is determined that the value of the print counter 3-15 is zero, the print register group 3-15 is determined to be zero.
Since there are no more pages to print on 9, printing ends.

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 management register of the page to be printed is read from the print management pointer 3-9-2 of the print register indicated by the print pointer 3-14.

In step 8-2, the page buffer indicated by the page buffer pointer 3-7-2 of the management register obtained in step 8-1 is specified to the printing node 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, the print/\-doware 3-5 transfers the print information (for one page) on the page buffer instructed in step 8-2 to the printing device 3-6, and 8, the transferred print information is printed.

Since the printing hardware 3-5 and the printing device 3-8 operate autonomously while printing one page, the CPt13-3
executes the page creation procedure for this one page during printing, and returns to the printing procedure in response to the one page printing completion signal from the printing device 3-6.

FIG. 8 shows steps 7-15 and step ? shown in FIG. -25 (the contents of both steps are the same), and shows in detail the procedure for setting odd page information to the print register.

In step 8-1, the double-sided spacing X is obtained from the double-sided spacing register 3-16.

In step 8-2, the X-th print register (the register corresponding to the odd-numbered page on the back side of the even-numbered page just printed) is set as counted in the printing direction from the position indicated by the print pointer 3-14.

In step 9-3, the contents of the separate register one before the separate register indicated by the separate read pointer 3-13 (i.e., the position of the management register corresponding to the odd-numbered page on the back side of the even-numbered page just printed) are read in step 9-3. Set the print management pointer 3-9-2 of the print register set in step 8-2.

In step 8-4, the value of part number counter 3-111-3 in the print register indicated by print pointer 3-14 is
Part number counter 3-9-3 in the Nth print register
Set to .

In step 8-5, the print flag 3-9-1 in the Nth print register is set to "possible".

Figure 10 shows the steps shown in Figure 7? -20 (detailed flowchart of the procedure for setting even page information to the print register).

In step 1O-1, the second print register counted in the printing direction from the position indicated by the print pointer 3-14 (that is, the register corresponding to the even-numbered side (first side) to be printed next to the even-numbered page just printed) 5.

In step 1O-2, the print management pointer 3 divides the contents of the separation register indicated by the separation read pointer 3-13 (that is, the position of the management register of the next page to be printed) into the previously set second print register. -9-2.

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

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

FIG. 11 shows step 7-28 and step ? shown in FIG. -32 (blank print execution procedure) is shown in detail.

In step 11-1, the CPU 3-3 instructs the printing hardware 3-5 and printing device 3-8 to print a blank page. Then, in step 11-2, a blank page is printed, and the CPU 3-3 executes a page creation procedure.

In the printing procedure of this embodiment described above, if printing on one side of even 6 pages is completed normally,
After opening the print register corresponding to that side (see step 7-9 and step 7-1O), select the odd page corresponding to the back side of the side just printed (steps ?-15, 7).
-18 and step? -25.Refer to 7-28) and the next even-numbered side after the printed side (see step ?-20.?-21) are set 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 cassette unit 1- shown in steps 7-15 and 7-25 ensures that the odd-numbered page on the back side of the trial sheet after printing an even-numbered page is printed on both sides of a single sheet. The page correspondence in is correct.

The procedure of steps 7-20 also ensures that even pages are printed in the correct page order. Therefore, step? -15/? -25 and step 7-2
By the page setting procedure 0, pages are set on the print register group 3-θ in the page order required for double-sided printing.

FIGS. 12(1) to 12(24) are schematic diagrams showing the state of double-sided printing according to this embodiment. Here, the ring equally divided radially by the broken line connects the ring-shaped print register group 3-9,
The arrow represents the print pointer 3-143-14, and the center of the ring represents the print counter. Further, the traveling direction (printing direction) of the print pointer 3-143-14 is clockwise in this figure. The arrow indicates the print register indicated by the print pointer 3-14, and the numbers in the ring-shaped print register group 3-8 indicate the number set in the print register, and the number written in the center circle of the ring. represents the value of print counter 3-15.

Is Figure 12 (1) a step in Figure 7? -3 and 7-
4, that is, the state immediately after setting the first page (second page) in the print register;
(23) represents the state immediately before entering step 7-22, and (24) in the same figure represents the state at the end of printing. Also, the numbers in the ring are erased with a backslash (\) because Indicates that the page has just been printed and the print register has been released. Furthermore, the print register in which the page number that is not erased with (\) is written has print flag 3-
9-1 indicates "possible", and other print registers indicate "not".

In FIGS. 12(1) to (24), the distance between both sides is M-5. The number of registers in print register group 3-9 is 10. Number of copies: 1.
The total number of pages is 18. This example shows a case where all pages are printed normally by normal printing (not sample printing). Each case will be explained in detail below.

FIG. 12(1) shows the state immediately after the second page to be printed for the first time is set.

Figure 12 (2) shows that the second page is printed (step 7-
8) and its print register is released (step 7-
9 and 7-10), the first page is the back of the second page.
page (see steps 7-15 and 7-16) and the second
The fourth page, which is the next even-numbered page, is set at the 9Nth page and the second page from the position of the print pointer 3-8 (steps ?-4 to 7-21 are passed).

FIG. 12(3) shows the state immediately after printing one blank sheet (see step 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. In addition, in double-sided printing according to this embodiment, paper feeding is performed for printing even-numbered pages, and the paper feeding interval is twice that in single-sided printing (that is, the timing for every other page). Therefore, in the early days of printing,
It is necessary to alternately print even-numbered pages and print blanks. FIGS. 12(1) to 12(5) show the transient state at the initial stage of printing.

In FIG. 12 (7), the first page, which is an odd numbered page, is printed (see step 7-8), and its print register is released (see steps 7-8 and ?-10).
The subsequent state is shown (the state immediately before step 7-22 after passing through steps 7-4 to ?-14).

12(6) to 12(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 4.3 alternately (that is, after printing an even page, the value is 3 → 4.
．． After printing odd numbered pages, the number becomes 4 → 3).

FIGS. 12 (18) to (23) show transitional states at the end of printing.

In Figure 12 (18), after printing the last 18th page (see step 7-6) and opening the register (see steps 7-9 and 7-10), set the 17th page on the back side in the print register. (Steps 7-15 and ?-16
reference). Here, the 18th page is the final page, and according to the judgment in step 7-19, the next page is "
"No", so the 20th page is never set.

After FIG. 12 (1B), paper feeding is not performed, and printing of odd-numbered pages and blank printing are performed alternately.

FIG. 12 (23) shows that the value of the print counter 3-15 becomes zero after printing the last odd-numbered page, the 17th page (that is, the back of the last page, the 18th page).
This shows the state where printing ends (12-24). As described in step 8-12 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 3-8 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 double-sided spacing M-7. 'The case where the number of print registers is minus 10 is shown.

In this figure, as in FIG. 12, the print register group 3-9 is represented by rings equally divided radially, and the print pointer 3-14 is represented by arrows. Further, the numbers in each section of the ring represent the page numbers set in each print register. Furthermore, the page number is crossed out with a backslash (\) to indicate that the print register for that page has just been released. Among the print registers, the print flag 3-8-1 in which a page number is written that has not been erased with a backslash indicates that the print flag 3-8-1 is "OK", and all others are "NO". In order to distinguish between even and odd pages, only even page numbers are enclosed in angle brackets ([,]).

The direction of movement (printing direction) of the print pointer 3-14 is clockwise. Further, the arrows shown outside the ring indicate the minimum range of print registers required at each point in time.

Furthermore, "M-1keJ, rM+1" shown on the outer periphery of the ring
"Ke" and "NikeJ,, rM-1ke" respectively indicate the number of print registers.

FIG. 13(1) shows a state in which a quick reference page (fL is an even number) is being printed. At this time, the page S existing on the print register is the (sentence-M) page in addition to the quick reference page.
Page, th (sentence-to +2) page, ..., th (1-3)
) are odd-numbered pages, and are the 1st, 3rd, ..., M-2nd, respectively, counting from the sentence page in the printing direction.
It is in the second place. Therefore, the number of print registers required in this case is (t1).

Figure 13 (2) shows that after printing the quick reference page, the
2) Counting the page in the print direction, the second (fL-1)
) page is set in the Xth print register. At this time, the unprinted odd pages that need to be placed on the print register are the (text - M) page, the (text - N ÷ 2)
Page... is the (vertical-1)th page. Since these odd-numbered pages are set every other page on the print register, in order for them to exist on the print register at the same time, the number of print registers needs to be (t1).

FIG. 13(3) shows a state in which the first page (k is an odd number) is being printed. At this time, the pages that should exist on the print register are the th page, the (k÷2)th page, and so on.

4 The odd numbered page of the (k10M'-1)th page and the (k+M'th)
+2) It is a page. Therefore, in this case, the number of print registers needs to be X or more.

FIG. 13 (4) shows the state after printing the first page, where after opening the print register for the first page, the state after printing the first page is
k+2) page, (k+4) page, ..., (k+4) page,
Since there are odd numbered pages (10M-1) pages and the (k÷2)th page, the number of print registers required is
Become an individual.

As is clear from the above explanation, print register group 3-8
The number of print registers is the maximum double-sided spacing M.

(odd number), it is sufficient if it is an even number of M, ÷ 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 (1), while printing the 1st sentence page (the sentences are even numbers), the 3rd (sentence-M) page, (u-M-2) page, . . . (Sentence-3) A total of 72 pages (M÷1), including odd numbered pages (total (M-1)/2 pages) and quick reference pages, are set.
It is sufficient if this many pages exist on the page buffer.

As shown in FIG. 13 (2), after printing the quick reference page and setting the 2nd (second) page and the 1st (first) page, the pages (u-M) and the -12)
Page, ..., the odd numbered page of the (fL-1)th page (
The total (T1)/2) and the (sentence + 2)th page (M
+1)/2 +1 page is set on the print register. Here, for the quick reference page, both the print register and the page buffer have just been released, and at this point, a new page has not yet been created on the page buffer where the first sentence page existed. ) page (even number) exists, naturally the (sentence/1)th page (odd number) also exists on the page buffer. Therefore, at the time shown in FIG. 13(2), (M
+1)/2 +3 A page buffer for one page is required.

As shown in FIG. 13 (3), while the first page (k is an odd number) is being printed, the second page, the kth page (k is an odd number), is displayed on the print register.
+2) Pages..., odd numbered pages of the (k+M-1)th page (total (M+1) 72 pages) and the (k+M+2)th page
There is a total of (M+1)/2 +l pages.

Further, as in FIG. 13(2), since the (k+M-1)th page exists on the page buffer, the number of page buffers required is (M+1)/2+2.

As shown in Figure 13 (4), after the first page is printed, the page is not opened in the second case (see Figure 13 (3))
Since this is the same as above, and a new page has not yet been created in the page buffer where the first page existed, the number of page buffers is (K''l)/2+2.

As is clear from the above explanation, the required minimum value of the page buffer γ number is (Mw +
1)/2 +3.

Next, the required minimum number of one separate register group 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 equal to or greater than the number of page buffers.

Now, the number of page buffers is 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 existing on the page buffer to the newest page on the page buffer (pages that have already been printed also remain on the separate register). In other words, for n9 minutes of the page buffer, the number of printed pages after the oldest page (even pages print before odd pages, so the oldest page is always an odd page) and the number of even pages in the page buffer release method is added.

In the cases shown in FIGS. 13 (1) and (2), the even-numbered pages before the quick reference page are open pages, and the oldest page is the (u-M)th page (odd number), so the (u-M)th )
The number of even pages between the page and the M (vertical-1) page is (M-1)/2. Therefore, the number of separate registers required is n÷(M-1)/2.
It is. This will be further explained as follows.

However, ) indicates a page that has already been printed and has been removed from the page buffer.

(odd) represents an odd numbered page.

Similarly, the cases of (3) and (4) in Figure 13 are expressed as 1
The result is as shown below.

(Light angle ridge register soft) TL+ and 5 - 1 or L x+1 Therefore, the required minimum number of separate registers is n0 (M
-1)/2.

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

In the printing device 3-8, when incorrect paper feeding is detected, the printing device 3-111 notifies the CPU 3-3 of the occurrence of the incorrect paper feeding, and discards the incorrectly fed sheet.゛The reason is that normal printing cannot be expected from incorrectly fed sheets, and sheets with abnormal printing cannot be mixed into normally printed sheets. This is because it is not desirable. Moreover, incorrectly fed sheets are likely to cause jams, and it is particularly undesirable to pass them through a complicated conveying element such as a reversing mechanism.

Sheets that have been incorrectly fed in the paper feed mechanism 1-1 (see Figure 1) are transferred to the post-fixing transport path 1 via the pre-transfer transport path 1-2.
-7, and reaches the pre-inversion branching mechanism 1-8. In this pre-reversal branching mechanism 1-8, branching to the pre-stacker transport path 1-12 is performed, unlike the case of normal paper feeding. The pre-stacker branching mechanism 1-14 branches and discharges the incorrectly fed sheet 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 a misfeed, even pages that would 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 (1) to (24) are schematic diagrams of a case I in which incorrect paper feeding occurs midway in the schematic diagram of double-sided printing shown in FIG. 12. 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.

14 (1) to (5) are exactly the same as FIG. 12 (1) to (5), so the explanation will be omitted.

FIG. 14 (6) shows the situation when incorrect paper feeding occurs when printing the sixth page.

If incorrect paper feeding occurs during printing in step 7-6 shown in FIG. 7, step 7-28
Branch to. In step 7-28, the print register for the odd 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 (11)). 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 step? -30, the even-numbered pages that could not be printed due to incorrect paper feeding are set in the print register for the next two even-numbered pages. 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 normally printed due to incorrect paper feeding is released.

Further, when passing through the paths of step 7-7 and steps 7-29 to 7-31, the number of pages set on the print register does not change, so the values of print counters 3 to 15 do not change.

The basic algorithm of the printing procedure according to this embodiment is that ``only after a certain even-numbered page has been successfully printed, set the odd-numbered page to be printed on the reverse side and the next even-numbered page to be printed''. . Therefore, even if incorrect paper feeding continues many times, the page order of the sheets stacked on the stacker will not be affected in any way.

Furthermore, as is clear from the explanation above, even if incorrect paper feeding occurs, the printing of that one sheet (two pages) is only delayed, and the reduction in throughput can be kept to a minimum. (See comparison of Figures 14 and 12). In other words, due to the incorrect paper feeding caused by FIG. 14 (8),
The printing is delayed by two pages (that is, one page) compared to the case of FIG. 12, and the 17th page is still unprinted in FIG. 14 (24).

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

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a sheet conveyance system of a duplex printing apparatus which is an embodiment of the present invention, and FIG. 2 shows the conveyance system shown in FIG. 1 and the state of sheets flowing over it. Schematic diagram, Figure 3 is a schematic diagram of an offline printing system to which the present invention is applied, Figures 4 (1) to (3) are diagrams showing the structure of registers etc. shown in Figure 3, Figure 5 is an initialization diagram. Flowchart showing the procedure, Figure 6 is a flowchart showing the page creation procedure, Figure 7 (1) and (2) is a schematic flowchart showing the printing procedure, Figure 8 is a detailed flowchart showing the printing procedure for one page, FIG. 9 is a detailed flowchart showing the procedure for setting odd-numbered pages, FIG. 1θ is a detailed flowchart showing the procedure for setting even-numbered pages, and FIG. 11 is a detailed flowchart showing the procedure for blank printing. Figures 12 (1) to (24) and (a) are schematic diagrams showing the situation during double-sided printing, respectively. Figures 14 (1) to (24) each show the response procedure in the event of incorrect paper feeding. It is a schematic diagram. 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 unit, 1-7...Fixing back conveyance path, 1-8...Pre-reversal branch Mechanism, 1-9... Pre-reversing conveyance path, 1-10... Reversing mechanism, 1-11... Reversing support conveying path, 1-12... Pre-stacker conveying path. 1-13...Stacker, 1-14...Stacker front branching mechanism, 1-15...Auxiliary tray, 2-1...Sheet conveyance loop, 2-2-1 to 2-2 -5... Sheets being conveyed, 3-1... Magnetic tape (MT). 3-2... Magnetic information conversion device, 3-3... Central processing unit (CP'U), G 3-4... Page buffer, 3-5... Printing hardware, 3-6. ...Printing device, 3-7...Management register group, 3-8...Separation register group, 3-8...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 number counter, 3-7-1... Page presence/absence flag, 3-7-2... Page buffer pointer, 3-8-1
...Separate management pointer, 3-9-1...Print flag (possible/inhibited), 3-9-2
...Print management pointer, 3-9-3...Part number counter. 3-9-4...Page index (even/odd), 5-1 to 5-
14.13-1~θ-12,7-1~? -32°8-1
〜8-4.9-1〜9-5.10-1〜10-4゜11
-1-11-2...Control step. Patent applicant Canon Co., Ltd. Figure 2 (3) Miguchi h (2) 7-21 to 7-29/7-22 to i25

Claims (1)

[Scope of Claims] l) A recording device capable of double-sided recording, characterized in that it is equipped with a control means that performs recording with a predetermined page relationship even in the case of incorrect paper feeding. 2) a first means for writing recorded information into a buffer memory in a predetermined order pattern; a second means for separating recorded information on the buffer memory into two types of groups during said writing; and a first means for writing recorded information on said buffer memory in parallel with said writing. 2. The recording apparatus according to claim 1, wherein the control means includes a third means for reading out the recorded information in a predetermined order pattern different from that in writing. 35 The control means is configured to maintain a predetermined page relationship between the front and back sides of the recording sheet and between the sheets in response to incomplete paper feeding that occurs during double-sided printing. A recording device according to claim 1, characterized in that: 4) The recording apparatus according to claim 1, further comprising the control means configured to minimize a decrease in throughput due to incomplete paper feeding during double-sided printing. (Margin below)