JPH10339975A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of making a double-sided printing operation most efficient by adjusting the number of recording papers in a device at any time, during a consecutive paper passage. SOLUTION: For instance, in the case the number of standby positions for the second surface (N2) is two, 'the number of sheets whose first surfaces are specified in printing - the number of sheets whose second surfaces are specified in printing' (N1) is three and the number of the recording papers is six, in a sequence of both-face printing operations, the first surfaces of the recording papers 1-3 are consecutively printed and then, the second surfaces of the recording papers 1 and the first surface of the recording paper 4 are alternately printed. In the case a reading time for the second surface of the recording paper 2 is late, when the second surface of the recording paper 4 is printed, three of the recording papers 2, 3 and 4 are fed into a double- sided paper feeding unit, so that jamming occurs because the number of the standby positions is only two. In such a case, printing order is changed to print the second surface of the recording paper 2, prior to the first surface of the recording paper 4. Further, it is judged whether the first surface is printed up to the N1 or not, in accordance with the transfer time of the second surface printed next time, to enable most efficient double-sided printing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital copying machine for performing double-sided printing.

[0002]

2. Description of the Related Art As a known technique for performing this type of double-sided printing, for example, a print control method for a printer disclosed in Japanese Patent No. 2522799 is known. The present invention
In a print control method of a printer that performs double-sided printing, during a paper feeding process from a paper feeding unit and a paper re-feeding unit, a paper feeding monitor that monitors a possibility of paper feeding from the paper feeding unit is performed, and a monitoring that paper feeding is impossible is performed. The remaining recording paper is fed preferentially from the re-feeding means based on the result, and the order of printing pages determined by a predetermined print sequence is changed so that the recording paper is re-fed to the first side of each re-supplied storage paper. The pages with different serial numbers of the printed pages are printed on the second surface, and the remaining recording paper having the first and second surfaces printed thereon is discharged.

[0003]

By the way, in such a double-sided printing system in which the first and second surfaces are alternately printed, the first surface is continuously arranged beyond the number of print standby positions on the second surface. The printing operation has been performed after the document could not be sent or a predetermined printing order was determined in advance. However, when the standby position of the recording paper is increased in the apparatus, the apparatus becomes larger, and when the image data is compressed and stored in the storage device, the image expansion speed differs depending on the image data. Printing on the first surface could not be performed continuously for more than a few.

In addition, if, for example, an image interface expansion error or a transfer error occurs before image output at the time of printing, the image transfer may be disabled if the print operation timing is delayed due to retransmission. In a case where the transfer becomes impossible with a sufficient margin, the image output waiting is canceled, and a process of discharging a blank sheet is performed. However, if printing on the first surface is continued for more than the number of standby positions, if the image output wait is delayed, the recording paper collides, causing a paper jam.

Further, in the above-mentioned conventional example, no consideration has been given to an apparatus provided with an interrupt operation or a post-processing device.

Accordingly, a first object of the present invention is to provide an image forming apparatus capable of adjusting the number of storage sheets in the apparatus at any time during continuous paper feeding and performing a two-sided printing operation most efficiently. It is in.

A second object is to prevent paper jams,
An object of the present invention is to provide an image forming apparatus excellent in operability.

It is a third object of the present invention to provide an image forming apparatus capable of performing an interruption operation and performing a two-sided printing operation more efficiently.

A fourth object of the present invention is to adjust the number of recording sheets in the apparatus at any time during continuous paper feeding by double-sided printing even in an image forming apparatus provided with a post-processing apparatus, so that double-sided printing can be performed most efficiently. An object of the present invention is to provide an image forming apparatus capable of performing an operation.

[0010]

The first means is the first means.
In order to achieve the object of (1), storage means for storing and reading out printing information successively for each page, and printing information of two pages out of the printing information stored in the storage means, are stored in the first and second surfaces of the recording paper. Printing means for printing on the respective surfaces, paper feeding means for feeding the recording paper to the printing means, re-feeding means for feeding the printed recording paper again to the printing means, Until the first printed recording paper reaches the introduction portion of the printing means again, the first surfaces of a plurality of new recording papers fed by the paper feeding means are arranged in a conveying path leading to the printing means. Thereafter, printing is performed on the second side of the first recording sheet, and thereafter, printing on the first side of the next new recording sheet fed by the paper feeding unit and the second side fed by the re-feeding unit are performed. And an image forming apparatus that alternately performs printing of
N1 is "the number of prints specified on the first side minus the number of prints specified on the second side", and N2 is "the number of standby positions at which printing on the second side can be stopped after printing the first side. , The relationship between the number of recording sheets stored in the storage means is set to “N”.
1> N2 ”or“ N1 ≦ N2 ”.

The second means is characterized in that in order to achieve the first object, the control means switches the number relationship in accordance with a read time of print information from the storage means.

In order to achieve the second object, the third means is the first or second means, wherein the image output start monitoring means from the storage means is connected to the image output start monitoring means within a preset time. Abnormality processing execution means for executing abnormality processing when image output is not started by the start monitoring means, wherein the control means switches the preset time in accordance with the relationship.

In a fourth aspect, in order to achieve the third object, in the first to third means, the operation is temporarily interrupted during a continuous image forming operation, and the operation shifts to an image forming operation in another mode. The control unit further includes an interrupt unit for performing the double-sided printing in a state of “N1> N2”, and when the interrupt unit requests an interrupt, the number relationship is set to “N1> N2”. ≦ N2 ”.

In a fifth aspect, in order to achieve the third object, in the fourth aspect, the control means includes a control unit for controlling the "N
1> N2, the interrupt operation is prohibited when continuous printing on both sides is performed, and when the continuous printing on both sides is performed in condition of N1 ≦ N2, the interrupt operation is automatically enabled. It is characterized in that the interrupt operation is switched to (1).

In a sixth aspect, in order to achieve the fourth object, in the first to fifth means, the post-processing apparatus for performing post-processing on a recording sheet discharged after performing image printing is further provided. Wherein the control means causes the next recording paper to wait at the introduction portion of the printing means until the post-processing is completed.

In order to achieve the fourth object, the seventh means is the first to fifth means, further comprising a post-processing device for performing post-processing on the recording paper discharged after image printing. Wherein the control means switches the number relationship in accordance with the operation of the post-processing device.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

[First Embodiment] FIG. 1 is a schematic structural view showing an image forming apparatus according to this embodiment. As shown in FIG. 1, a document bundle placed on a document table 2 of an automatic document feeder (hereinafter, referred to as "ADF") 1 with its image side down is placed on an operation unit 30 (FIG. 2). When the start key 34 is pressed, the document at the lowest position is fed by the feed roller 3 and the feed belt 4 to the reading position of the process on the contact glass 6. After reading the image data of the document on the contact glass 6 by the reading unit 50, the read document is discharged by the feed belt 4 and the discharge roller 5. Further, when the document set detection sensor 7 detects that the next document is present on the document table 2, the document is fed onto the contact glass 6 in the same manner as the previous document. The feed roller 3, the feed belt 4, and the discharge roller 5 are driven by a transport motor 26 as shown in FIG.

The recording sheets stacked on the first tray 8, the second tray 9, and the third tray 10 are fed by the first sheet feeding device 11, the second sheet feeding device 12, and the third sheet feeding device 13, respectively. ,
The sheet is transported by the vertical transport unit 14 to a position where it contacts the photoconductor 15. The image data read by the reading unit 50 is written on the photoconductor 15 by the laser beam from the writing unit 57, and
7, a toner image is formed. The toner on the photoconductor 15 is transferred while the recording paper is conveyed by the conveyance belt 16 at the same speed as the rotation of the photoconductor 15. Thereafter, the image is fixed by the fixing unit 17, and the image is discharged to the discharge tray 19 by the discharge unit 18.

The recording paper starts to be conveyed from the registration roller 20 in front of the photoconductor at the same timing as the writing of the image data, and the printing position of the image on the photoconductor 15 is adjusted on the recording paper. At this time, if the image transfer to the primary storage device described later is delayed, the writing timing is delayed, so that the recording paper stops before the registration roller 20 and waits. Normal,
When the standby time exceeds a predetermined time, the recording paper in standby is discharged as a blank sheet without printing as abnormal processing.

When images are formed on both sides of the recording paper,
The recording paper fed from each of the paper feed trays 8 to 10 and formed into an image is not guided to the paper output tray 19, and the recording paper is set in the reversing unit by setting the branch claw 112 for path switching on the upper side. 113, the front end and the rear end are exchanged, and the double-sided paper feeding unit 11
It is transported inside 1. At this time, if there is a recording sheet being printed, the first standby position 114 and the second standby position 1
At 15, the recording paper temporarily stops and waits until printing is possible. Thereafter, the recording paper that has been waiting at the first and second standby positions 114 and 115 is re-fed from the double-sided paper feeding unit 111 to transfer the toner image formed on the photosensitive member 15 again, and Is printed, the branching pawl 112 for switching the path is set on the lower side, and guided to the paper discharge tray 19. The double-sided paper supply unit 111 is used for forming images on both sides of the recording paper in this manner.

The photoconductor 15, the transport belt 16, the fixing unit 17, the paper discharging unit 18 and the developing unit 27 are driven by a main motor 25 (FIG. 4). Each of the paper feeding units 11 to 13 controls the driving force of the main motor 25. The transmission is controlled by the paper feed clutches 22, 23, 24, respectively. The transmission of the driving force of the main motor 25 to the vertical transport unit 14 is controlled by the intermediate clutch 21.

FIG. 2 shows the operation unit 30. In the figure, an operation unit 30 includes a liquid crystal touch panel (display) 31, a numeric keypad 32, a clear / stop key 3
3, a print key 34, a mode clear key 35, and an initial setting key 38 are provided. The liquid crystal touch panel 31 is provided with a mode setting function key 37, and displays a message indicating the number of copies and the state of the image forming apparatus. .

FIG. 3 shows a liquid crystal touch panel 31 of the operation unit 30.
It is a figure which shows an example of a display. As can be seen from the figure, when the operator touches a key displayed on the liquid crystal touch panel 31, the key indicating the selected function is inverted to black. Further, when it is necessary to specify the details of a function such as a scaling value at the time of performing scaling, by touching a key, a detailed function setting screen is displayed. As described above, since the liquid crystal touch panel uses the dot display device, the optimum display at that time can be graphically performed.

In this liquid crystal touch panel, as can be seen from FIG. 3, a message area for displaying a message such as "You can copy."
On the right is a copy number display that displays the number of sheets set, below it is an automatic density key that automatically adjusts the image density, an automatic paper selection key that automatically selects the recording paper, and one copy at a time. Sort key to specify the alignment process, stack key to specify the process of sorting the copies for each page, staple key to specify the process of binding the sorted items one by one, the same size key to set the magnification to the same size, enlarge / A scaling key for setting the reduction ratio, a two-sided key for setting the duplex mode, an erase / move key for setting the binding margin mode, etc., and a link for printing out a large number of print operations through a digital copier network A mode key and the like are provided. Since the display screen is switched, a part of the above is shown in this figure, and the key corresponding to the selected mode is shaded for the selected mode.

FIG. 4 is a block diagram showing a control device centering on the main controller. In the figure, a main controller 20 includes an operation unit 30 for performing display to an operator, input of function setting from the operator, control of a scanner, control of writing a document image in a memory, and control of forming an image from an image memory. Image processing unit (IPU) 49, etc., and automatic document feeder (ADF)
1 and the like. Each decentralized control device and the main controller 20 exchange machine status and operation commands as needed. Further, a main motor 25 and a conveyance motor 26 necessary for paper conveyance, etc.
Various clutches 21 to 24 are also connected.

The operation of reading an image and forming a latent image on the recording surface of the photoreceptor in the image forming apparatus constructed as described above will be described below. Here, the latent image is a potential distribution generated by converting an image into optical information and irradiating the image on the surface of the photoconductor.

First, the reading unit 50 includes a contact glass 6 on which an original is placed and an optical scanning system. The optical scanning system includes an exposure lamp 51, a first mirror 52, and a lens 5.
3, a CCD image sensor 54, a second mirror 55, a third mirror 56, and the like. The exposure lamp 51 and the first mirror 52 are fixed on a first carriage (not shown), and the second mirror 55 and the third mirror 56 are fixed on a second carriage (not shown). When reading a document, the first carriage and the second carriage are mechanically scanned at a relative speed of 2: 1 so that the optical path length does not change. This optical scanning system is driven by a scanner drive motor (not shown).

The original image is read by the CCD image sensor 54, and is converted from an optical signal into an electric signal and processed. By moving the lens 53 and the CCD image sensor 54 in the left and right directions in FIG. 1, the image magnification can be changed. That is, the position of the lens 53 and the CCD image sensor 54 in the left-right direction in the figure is set corresponding to the designated magnification.

The writing unit 57 includes a laser output unit 58, an imaging lens 59, and a mirror 60.
Inside the laser output unit 58, there is provided a polygon mirror that rotates at a constant high speed by a motor and a laser diode as a laser light source.

The laser light emitted from the laser output unit 58 is deflected by the polygon mirror that rotates at a constant speed, passes through the imaging lens 59, is turned back by the mirror 60, and is condensed on the surface of the photoreceptor to form an image. . The deflected laser light is exposed and scanned in a so-called main scanning direction orthogonal to the direction in which the photoconductor 15 rotates.
4, the recording of the image signal output in line units is performed. An image, that is, an electrostatic latent image is formed on the surface of the photoconductor by repeating main scanning at a predetermined cycle corresponding to the rotation speed and the recording density of the photoconductor.

The laser beam output from the writing unit 57 is applied to the photosensitive member 15 of the image forming system, and the main scanning synchronization signal is applied to the laser irradiation position near one end of the photosensitive member 15 (not shown). Is provided. Based on the main scanning synchronization signal output from the beam sensor, control of image recording timing in the main scanning direction and generation of a control signal for input / output of an image signal described later are performed.

The configuration of the image processing unit (IPU-image reading unit and image writing unit) will be described with reference to FIG.

The illumination light emitted from the exposure lamp 51 irradiates the document surface and is reflected by the document surface. The reflected light is imaged by an imaging lens (not shown), enters the light receiving surface of the CCD image sensor 54, is photoelectrically converted, and is converted into a digital signal by the A / D converter 61. The image signal converted into the digital signal is subjected to shading correction by a shading correction unit 62, and then MTF correction and γ correction are performed by an image processing unit 63. The selector 64 switches the destination of the image signal to the scaling unit 71 or the memory controller 65 and selects either one. The image signal that has passed through the scaling unit 71 is scaled according to the scaling factor, and sent to the writing unit 57. The image memory controller 65 and the selector 64 are configured to be able to bidirectionally input and output image signals. Although not explicitly shown in FIG. 4, as shown in FIG. 5, the image processing unit (IPU) 49 can process image data supplied from outside in addition to image data input from the reading unit 50. A function of selecting input / output of a plurality of data is also provided. The image data supplied from the outside is, for example, data output from a data processing device such as a personal computer as shown in FIG. 5, and in FIG. 5, the first print synthesizing section 72 and the second This is shown as a print combining unit 73. In this example, the first print synthesizing section 72 performs print synthesis of the print image data 74 with respect to the output from the processing section 63, and the second print synthesis section 74.
In this example, print synthesis of print image data 74 is performed on image data sent to the scaling unit 71.

An image processing unit (IPU) 49 controls the reading unit 50 and the writing unit 57 by setting the image memory controller 65 and the like.
And a ROM for storing programs and data of the CPU 68
69 and a RAM 70. Note that the CPU 68
Is an image memory 66 via an image memory controller 65
Can be written and read. Each of these units communicates with the outside via an I / O port 67.

Here, the image signal for one page in the selector 64 will be described with reference to the timing chart of FIG.

/ FGATE indicates the effective period of one page of image data in the sub-scanning direction. / LSYNC is a main scanning synchronization signal for each line, and the image signal becomes valid at a predetermined clock after this signal rises. The signal indicating that the image signal in the main scanning direction is valid is / LGA
TE. These signals are synchronized with the pixel clock VCLK, and data of one pixel is sent for one cycle of VCLK. The image processing section 49 adds separate / FGATE, / LSYNC, /
It has a LGATE and VCLK generation mechanism, and enables various image input / output combinations.

Referring to FIG. 7, the memory controller and image memory in FIG. 5 will be described in detail.

The memory controller 65 includes an input data selector 701, an image synthesizer 702, and a primary compression / decompression unit 7.
03, comprising an output data selector 704 and a secondary compression / decompression unit 705. Setting of control data to each part is CP
This is done by U68. Addresses and data in FIG. 7 indicate image data, and data and addresses connected to the CPU 68 are not shown.

The image memory 66 includes primary and secondary storage devices 706 and 707. Primary storage device 706
For example, a memory that can be accessed at high speed, such as a DRAM, is used so that data writing to the memory or data reading from the memory at the time of image output is performed at a high speed in synchronization with the transfer speed of the input image data. The primary storage device 706 is configured to be able to divide into a plurality of areas (areas) according to the size of the image data to be processed and simultaneously execute input and output of image data. That is, in order to be able to execute image data input and output in parallel for each divided area, two sets of read / write address / data lines are connected to the interface with the memory controller 65. . This enables, for example, an operation of outputting (reading) an image from area 2 while inputting (writing) an image to area 1.

The secondary storage device 707 is a large-capacity memory for storing data for synthesizing and sorting input images. Primary and secondary storage devices 706, 7
If an element capable of high-speed access is used for both 07,
Next, data processing can be performed without distinction between secondary and secondary, and control becomes relatively simple. However, since elements such as DRAM are expensive,
The access speed to the secondary storage device is not so fast,
Inexpensive and large-capacity storage media are used, and processing of input / output data is performed via a primary storage device. By employing such a configuration of the image memory, it is possible to realize processing such as input / output, storage, and processing of a large amount of image data with an inexpensive and relatively simple configuration.

The operation of the memory controller 65 will be briefly described. The operation is divided into image input, image output, and image input / output. Therefore, these will be individually described.

1. Image Input (Storage in Image Memory) The input data selector 701 selects image data to be written into the image memory (primary storage device 706) from a plurality of data. The image data selected by the input data selector 701 is supplied to the image synthesizing unit 702, and can be synthesized with the data already stored in the image memory. The image data processed by the image synthesis unit 702 is compressed by the primary compression / decompression unit 703, and the compressed data is written to the primary storage device 706. The data written to the primary storage device 706 is
If necessary, the data is further compressed by the secondary compression / decompression unit 705 and then stored in the secondary storage device 707.

2. Image Output (Read from Image Memory) At the time of image output, image data stored in the primary storage device 706 is read. When the image to be output is stored in the primary storage device 706, the image data in the primary storage device 706 is decompressed by the primary compression / decompression unit 703, and the decompressed data or the decompressed data is obtained. The output data selector 704 selects and outputs data after image synthesis of the input data and the input data. The image synthesizing unit 702 includes:
Processing such as combining the data in the primary storage device 706 with the input data and selecting the output destination of the combined data is performed. In addition,
The synthesizing has a function of adjusting the phase of the image data. In the selection, image output, write-back to the primary storage device 706, and simultaneous output to both output destinations are set. If the image to be output is not stored in the primary storage device 706, the image data to be output stored in the secondary storage device 707 is converted to the secondary compression / decompression unit 70.
5, and the data after expansion is stored in the primary storage device 706.
After that, the above-described image output operation is performed.

FIG. 8 is a schematic diagram showing the printing order in this embodiment. The standby position (N2: fixed value) of the second surface provided in the re-feed path 200 is the first and second standby positions 114 and 115 described above, and the number of sheets (P: (Fixed value) is 3 sheets, and “number of sheets for which printing is specified on the first side−number of sheets for which printing is specified on the second side” is N1.
FIG. 7 is an explanatory diagram illustrating a (double-sided) double-sided printing sequence according to the present embodiment in which six recording sheets are used. FIG. 8A shows a printing order at the time of high-speed printing, and FIG. 8B shows a printing order when an abnormal process occurs in the middle.

In this sequence, when the reading time of the second side of the recording paper 2 is slow, for example, when a delay occurs due to a large amount of data, the first side of the recording paper 4 is printed. Three recording papers 2, 3, and 4 are fed into the unit, and there are only two standby positions, which causes a paper jam. Therefore, in such a case, the printing order is changed so that the second surface of the recording paper 2 is printed before the first surface of the recording paper 4. In this embodiment, thereafter, it is determined that there is no delay in the reading time of the second side of the third recording paper, and the printing order returns to the high-speed processing mode.

FIG. 9 shows a processing procedure for determining the printing order of this apparatus.
Is shown in the flowchart of FIG. In this processing, first, it is checked whether or not printing of the first side of the recording paper in this job has been completed (step 901). Next, N1 ≧
P is checked (step 902), and if YES, the next print is connected to the second side execution queue so as to print on the second side (step 903).

In the case of NO, N1 ≧ N2 is checked (step 904), and in the case of NO in this check, the next printing is connected to the first-side execution queue so as to be the first side (step 906). If YES, the second to be printed next
The reading time of the surface from the image memory 65 is predicted (step 905), and if it is too late, it is connected to the execution queue so as to print the second surface (step 903). As soon as possible, the first-side execution queue is connected to the first-side execution queue (step 906). Then, when the order of all the prints is determined, this processing is ended (YES in step 907).

As described above, according to the present embodiment, it is possible to adjust the number of recording papers in the apparatus to an appropriate number in a timely manner during continuous paper feeding, whereby the two-sided printing operation can be performed most efficiently. It can be performed.

The recording paper stops at the position of the registration roller 20 and waits until the writing of image data is started. For example, when an image expansion error or a transfer error occurs, a printing operation is performed to perform re-transfer. Timing may be delayed or image transfer may not be possible. Therefore, in a case where the transfer becomes impossible after a lapse of a sufficient time, the image output wait is canceled and an abnormal process such as discharging a blank sheet is performed. However, the number of refeeding paths 2 exceeds the number of standby positions.
If the conveyance of the recording paper is continued within 00, if the image output waiting is delayed, the recording paper will collide, causing a paper jam.
Therefore, if it is determined that image transfer takes time,
Switch the time until entering the error processing to shorten it.

The processing procedure at this time is shown in the flowchart of FIG. In this process, when the recording paper starts feeding and reaches a printable position, the process enters a routine of waiting for FGATE, in other words, waiting for image output. The counter C is cleared when this routine is entered (step 10).
01). If the number of recording papers (N1) that are waiting for printing on the second side and the first side is being printed and conveyed is larger than the number of standby positions (N2) (YES in step 1002), S1 is set to the FGATE waiting timeout time Tout. Enter (Step 1
003). Otherwise (NO in step 1002)
In step S1004, S2 is input to the FGATE waiting timeout time Tout. In these cases, of course,
The values are set to satisfy S1 <S2. After the processing of steps 1003 and 1004, the process waits for the start of FGATE output (step 1005). If FGATE is output, normal printing operation is started (step 1006). On the other hand, if the counter value C exceeds Tout (step 100)
(YES in 7) A blank sheet discharging operation is executed as an abnormal process (step 1008). It should be noted that the counter value C is counted up at regular intervals by another control (not shown).

As described above, according to the present embodiment, the abnormality processing is executed in a timely manner, so that the operability is improved.

[Second Embodiment] Next, a second embodiment will be described. Note that the image forming apparatus itself is the same as that shown in FIGS. 1 to 7 shown in the above-described first embodiment, and a duplicate description will be omitted.

FIG. 11 is an explanatory diagram showing a double-sided printing sequence according to the second embodiment. The standby position (N2: fixed value) of the second surface provided in the paper re-feeding path is the first and second standby positions 114 and 115, and the number of sheets (P: fixed) that can exist in the apparatus. ) Is N1 and “number of pages designated for printing on the first side−number of pages designated for printing on the second side” is N1.
(Variable), showing a sequence of six recording sheets.

This apparatus basically has N2 as "2",
Although the value of "3" is alternately substituted, the determination is made after the interrupt key is pressed, and when N1 = 2 (= N2), the double-sided printing is interrupted to execute the interrupt processing. Thereafter, one-sided printing of the interrupted recording paper is performed (four sheets in this embodiment), and double-sided printing is restarted upon completion. At that time, printing can be performed on the recording paper so that N1> N2 so that the two-sided printing operation can be performed most efficiently. Specifically, instead of performing printing on the second side of the recording paper existing in the apparatus, a new recording paper is supplied and recording is performed on the first side of the recording paper. By doing so, it is possible to shift the interrupt processing quickly while increasing the efficiency of double-sided printing. Here, the interruption operation when the interruption key is pressed is described. For example, in the case of an image forming apparatus having a function of copying, printing, facsimile, etc. by one unit, the printer performs double-sided printing. It is also conceivable that printing may be interrupted by fax reception while the printer is in operation.

The processing procedure of FIG. 11 is described in FIG. 12 and FIG.
3 is shown in the flowchart. In this process, normal double-sided printing control is performed until the interrupt key is pressed (NO in step 1201, step 1209). If the interrupt key is pressed and the relationship of N1> N2 holds,
The next print is connected to the execution queue so as to print on the second side of this series of prints. Number of recording papers (N
If 1) is larger than the number of standby positions (N2) for the duplex paper supply unit (YES in step 1201; YE in 1202)
S), after printing the next second side (step 1203),
The two-sided printing is interrupted (step 1204). On the other hand, if N1> N2 is not satisfied in step 1202, the printing is interrupted immediately or at the end of the currently performed printing (step 1204). Interrupt printing is performed until the interrupt printing is completed (steps 1205 and 1206).
When the interrupt printing is completed, double-sided printing is restarted (step 1207). Thereafter, normal double-sided printing control is executed (step 1208), and when the double-sided printing is completed (step 1209), this processing ends.

In the interrupt processing using the above-described interrupt key, inhibition and permission of the interrupt key are controlled in accordance with the number of recording sheets during the first-side printing conveyance as shown in the flowchart of FIG. That is, the number of recording papers (N1) during the first-side printing conveyance is equal to the number of standby positions (N
2) If the number exceeds 2, interrupt processing is prohibited (YES in step 1301, 1302), and the duplex printing control is executed until the duplex printing is completed (steps 1304, 130).
5) If the number of recording papers (N1) during the first-side printing conveyance is equal to or smaller than the number of standby positions (N2) of the double-sided paper supply unit, the interruption processing is permitted.

As described above, it is possible to adjust the number of recording sheets in the apparatus even if an interrupt process is entered during continuous two-sided sheet passing.

FIG. 14 is an explanatory diagram showing a double-sided printing sequence according to the third embodiment. The standby position (N2: fixed value) of the second surface provided in the re-feeding path 200 is the first and second standby positions 114 and 115 shown in FIG.
The number of pieces (P: fixed value) that can be present in the device,
N1 (variable) and "sequence of six sheets of recording paper" indicate "the number of sheets designated for printing on the first side minus the number of sheets designated for printing on the second side". In addition, the present apparatus is equipped with a finisher 100 as a post-processing apparatus instead of the discharge tray 19 of FIG.

The finisher 100 normally transfers the transfer paper conveyed by the paper discharge unit 18 of the main body to the discharge rollers 1.
It can be guided in the 02 direction and the stapling section direction. Further, by switching the branch deflecting plate 101 upward, the sheet can be discharged to the sheet discharge tray (stacker tray) 104 via the transport roller 103. Further, by switching the branch deflecting plate 101 downward, the sheet can be conveyed to the staple tray 108 via the conveying rollers 105 and 107. The transfer paper stacked on the staple tray 108 is aligned with the jogger 109 for paper alignment each time one sheet is discharged, and a copy is completed and the stapler 106 binds the paper. The transfer paper group bound by the stapler 106 is stored in the stapling completed paper discharge tray (fall tray) 110 by its own weight.

On the other hand, the normal paper discharge tray 104 is a paper discharge tray that can move back and forth, and moves forward and backward for each paper discharge tray section, each document, or each copy sorted by the image memory, and is discharged. The coming copy paper is simply sorted. In FIG. 15, the same components as those in FIG. 1 described above are denoted by the same reference numerals, and redundant description will be omitted.

In this sequence, as can be seen from FIG. 14, the first side is continuously printed from recording papers 1 to 3, and then the second side of recording paper 1 and the first side of recording paper 4 are alternately printed. I do. After printing and discharging the second surface of the recording paper 3, a stapling operation is performed. The next printing operation is stopped until this stapling operation is completed, and the target recording paper is moved to the registration roller unit 2.
Wait at 0. Therefore, the stapling operation can be executed reliably. If the printing operation is performed before the stapling operation is completed (in this embodiment,
The printing on the first side of the recording paper 6) and then the recording paper to be discharged (recording paper 4 in this embodiment) may be discharged during the stapling operation. After printing is completed after stapling is completed, instead of printing on the first side of the recording paper (recording paper 6 in this embodiment), the second side of the recording paper (recording paper 4 in this embodiment) is printed. It is also possible to specify to do so. Therefore, the control in this case is divided into two.

When stopping the first side of the recording paper 6 (FIG. 14C): The condition for stopping the first side of the recording paper 6 is as follows.
This is the case where the paper printed before that is stapled at the end of the set and discharged from the staple tray 108. Therefore, if the recording paper 6 or the recording paper 4 is
Even if the paper is ejected to another tray (for example, the stacker tray 104) instead of entering the printer (for example, if the output from the printer is mixed during copying), the operation is stopped, which is inefficient. To avoid this, the paper is already full at the double-sided stop position and the next second side (here, recording paper 4
Of the recording paper 6 must be stopped due to complicated conditions such that the second surface of the recording paper 6 enters the staple tray 108.

When the second side of the recording paper 4 is stopped first (FIG. 14 (d)): If the second side of the recording paper 4 is a sheet which enters the staple tray 108, it may be stopped. Therefore, the stop condition becomes easy, so that the number of program steps and the memory capacity can be reduced.

FIG. 16 is a flowchart showing a processing procedure for determining the printing order of this apparatus. In this process, first,
It is checked whether or not printing of the first side of the recording paper in this job has been completed (step 1601). Next, N1 ≧ P is checked (step 1602), and YE
In the case of S, the next print is connected to the second-side execution queue so as to print on the second side (step 1603).

If the check at step 1602 is NO, the number relationship N1 ≧ N2 is further checked (step 1604). If the check is NO, the first printing is performed so that the next printing is performed on the first surface. Connect to the execution queue (step 1606). On the other hand, in the case of YES, it is checked whether the post-processing of the recording paper on which the second side has been printed immediately before is staple (step 1605). If the post-processing of the recording paper is staple, the recording paper is connected to the execution queue so as to perform printing on the second side (step 1603). On the other hand, if the staple is not found in the check in step 1605, the first side execution queue is connected (step 1607).
Then, when the order of all the prints is determined, this processing is ended (YES in step 1908).

[0067]

As is apparent from the above description, according to the first aspect of the present invention, "the number of pages designated for printing on the first side minus the number of pages designated for printing on the second side" is N1. ,
When "the number of standby positions at which the second-side printing can be stopped after printing the first-side printing" is N2, the relationship between the number of recording sheets stored in the storage means is "N1>N2" or "N1". ≤N
Since the control means for switching between "2" and "2" is provided, it is possible to adjust the number of recording papers in the apparatus at any time during continuous paper feeding, thereby enabling the most efficient double-sided printing operation.

According to the second aspect of the present invention, the relation of the number of sheets described in the first aspect can be switched according to the read time of the print information from the storage means.
An effect equivalent to that of the described invention can be obtained.

According to the third aspect of the present invention, the image output start monitoring means from the storage means and the abnormal processing are executed when the image output start monitoring means does not start the image output within a preset time. An abnormality processing execution unit is further provided, and the control unit can switch the preset time according to the relationship, so that operability can be improved.

According to the fourth aspect of the present invention, there is further provided an interrupting means for temporarily suspending the operation during the continuous image forming operation and enabling a transition to an image forming operation in another mode. If there is an interrupt request during duplex printing in the state of “N1> N2”, the number relationship is switched to “N1 ≦ N2”. It is possible to adjust the number of sheets of paper, thereby providing the same effect as the first aspect of the present invention.

According to the fifth aspect of the present invention, the control means inhibits the interrupt operation when continuous printing on both sides is performed in the state of “N1> N2”, and “N1 ≦ N”.
When double-sided continuous printing is performed in the state of "2", the interrupt operation is automatically switched so as to permit the interrupt operation, so that the same effect as the invention of claim 4 can be obtained.

According to the sixth aspect of the present invention, there is further provided a post-processing device for performing post-processing on the recording paper discharged after printing the image, and the control means controls the next recording until the post-processing is completed. Since the paper is made to stand by at the introduction portion of the printing means, stapling can be performed reliably while ensuring the efficiency of double-sided printing.

According to the seventh aspect of the present invention, the relation of the number of sheets can be switched according to the operation of the post-processing apparatus, and the number of recording sheets in the apparatus can be adjusted at any time during continuous duplex sheet feeding. The two-sided printing operation can be performed most efficiently.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating an operation unit of the image forming apparatus of FIG. 1;

FIG. 3 is a diagram showing a display state of a liquid crystal touch panel of the operation unit in FIG. 2;

FIG. 4 is a block diagram illustrating a schematic configuration of a control device in the image forming apparatus of FIG. 1;

FIG. 5 is a block diagram showing details of the IPU of FIG. 4;

6 is a timing chart showing the timing of an image signal in the selector of FIG.

FIG. 7 is a block diagram showing details of a memory controller and an image memory in FIG. 5;

FIG. 8 is a diagram illustrating a sequence of double-sided printing of the image forming apparatus according to the first embodiment.

FIG. 9 is a flowchart showing a processing procedure in the double-sided printing sequence of FIG. 8;

FIG. 10 is a flowchart showing a sequence of a double-sided printing abnormality process in FIG. 8;

FIG. 11 is a diagram for explaining a double-sided printing sequence for interrupting the image forming apparatus according to the second embodiment.

FIG. 12 is a flowchart showing a processing procedure in the sequence of FIG. 11;

FIG. 13 is a flowchart showing a processing procedure when interrupts are permitted and not permitted in the sequence of FIG. 11;

FIG. 14 is a diagram for explaining a double-sided printing sequence for performing post-processing of the image forming apparatus according to the second embodiment.

FIG. 15 is a schematic configuration diagram illustrating an image forming apparatus provided with a post-processing device.

FIG. 16 is a flowchart showing a processing procedure in the sequence of FIG.

[Explanation of symbols]

 Reference Signs List 20 main controller 30 operation unit 49 image processing unit (IPU) 54 CCD 57 writing unit 61 A / D converter 62 shading correction unit 63 image processing unit 64 selector 65 memory controller 66 image memory 68 CPU 69 ROM 70 RAM 71 scaling unit 72 Editing unit 701 Input selector 702 Image synthesis unit 703 Primary compression / expansion unit 704 Output data selector 705 Secondary compression / expansion unit 706 Primary storage device 707 Secondary storage device

Claims (7)

[Claims] 1. A storage means for storing and reading out print information successively for each page, and print information for two pages out of the print information stored in the storage means, on a first side and a second side of a recording paper. A printing means for printing, a paper feeding means for feeding the recording paper to the printing means, a re-feeding means for feeding the printed recording paper again to the printing means, and a printing means for printing on the first surface. Until the first recording paper reaches the introduction portion of the printing means again, the first surfaces of a plurality of new recording papers fed by the paper feeding means are continuously arranged in the transport path to the printing means, and thereafter, Printing on the second side of the first recording sheet, printing on the first side of the next new recording sheet fed by the paper feeding unit, and printing on the second side fed by the re-feeding unit In the image forming apparatus that alternately performs Number of copies - the number "which print designation is made on the second surface N1," after the first surface printing, when the number of standby position that can wait to stop the second side printing "and the N2,
The relationship between the number of recording sheets stored in the storage means is expressed as "N1>
An image forming apparatus comprising a control unit for switching between “N2” and “N1 ≦ N2”. 2. The image forming apparatus according to claim 1, wherein the control unit switches the number-of-sheets relationship according to a reading time of print information from the storage unit. 3. An image output start monitoring unit from the storage unit, and an abnormality process execution unit executing an abnormality process when the image output start monitoring unit does not start image output within a preset time. 3. The image forming apparatus according to claim 1, further comprising: the control unit switches the preset time according to the relationship. 4. An image forming apparatus according to claim 1, further comprising interrupt means for temporarily suspending an operation during a continuous image forming operation and allowing a transition to an image forming operation in another mode. 5. The apparatus according to claim 1, wherein when two-sided printing is performed in the state, when an interrupt request is issued by the interrupt unit, the number relationship is switched to “N1 ≦ N2”. 6. Image forming device. 5. The control unit prohibits the interrupt operation when performing double-sided continuous printing in the state of “N1> N2”, and executes double-sided continuous printing in a state of “N1 ≦ N2”. 5. The image forming apparatus according to claim 4, wherein the interrupting operation is automatically switched so as to permit the interrupting operation. 6. A post-processing device for performing post-processing on a recording sheet discharged after performing image printing, wherein the control unit controls a next recording sheet to be introduced into the printing unit until the post-processing is completed. The image forming apparatus according to any one of claims 1 to 5, wherein the image forming apparatus is caused to stand by at (1). 7. The image forming apparatus according to claim 1, wherein the control unit switches the number relationship according to an operation of the post-processing device.