JPH11258862A - Image forming device and method and storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten recording paper ejection throughput by forming a blank image from blank data and an image clock in order to take synchronization with the completion of paper supply preparation for printing on a blackside and supplying recording paper from a double-sided unit for printing on the back surface after forming the image of the backside. SOLUTION: Double-sided monochrome printing is started (ST200). The image is formed on a transfer belt, the recording paper is supplied from a cassette, and the image is transferred to the recording paper (ST201 to ST203). The recording paper is carried to the double-sided unit and blank data printing is performed (ST204 and ST205). Next, the image is formed on the transfer belt, the recording paper is supplied from the double-sided unit, and the image is transferred to the recording paper (ST207 to ST209). Then, the recording paper is carried to a main body paper ejection part so as to decide the existence of the next image (ST210 to ST211). When the image does not exist, electrophotographic process is finished. By forming the blank image instead of performing finishing processing, the throughput is shortened by taking the synchronization with the completion of the paper supply preparation for printing on the backside.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electrophotographic image forming apparatus and method, and a recording medium.

[0002]

2. Description of the Related Art As a conventional example, the structure of a multicolor image forming apparatus will be described below with reference to FIG. The latent images formed for each color by the optical unit 107 on the image carrier 100 are developed by the respective color developing units Dy, Dc, Dm, and Dk, and are transferred onto the outer periphery of the transfer belt 103 a plurality of times to form a multicolor image. Is formed. Here, the transfer belt 103
A high voltage is applied thereon to transfer the toner onto the transfer belt 103. Next, the paper feed unit 101 or the paper feed tray 10
The recording paper 102 fed from the printer 6 is conveyed by the paper path shown in FIG. After that, the recording paper 102 is transported by the transport roller 111, is fixed by the fixing unit 104, and is discharged to the discharge tray unit 108 or the discharge unit 109. Here, each color developing device has a rotation support shaft at both ends thereof, each of which is rotatably held on the developing device mechanism 110, and each developing device is rotated for selecting a developing device. You. Reference numeral 112 denotes a cleaning unit for cleaning toner on the transfer belt 103, and reference numeral 113 denotes a waste toner unit for holding waste toner from the image carrier 100. 1
Reference numerals 20 and 121 denote jam sensors for detecting a recording paper jam. Reference numeral 120 denotes a paper feed unit jam sensor that detects a jam in the paper feed unit, and 121 denotes a paper discharge unit jam sensor that detects a jam of the fixing unit. The paper supply unit has a recording paper size sensor 114 for detecting the recording paper size.

FIG. 6 is a block diagram of a control system for image formation and recording paper transport of a conventional apparatus. FIG. 1 is a block diagram showing only controls related to image formation and recording paper conveyance, and does not show other controls. Reference numeral 10 denotes an image forming apparatus. A control unit 21 receives an image clock signal and an image signal from the controller 3 and emits a laser beam for recording sheet conveyance and image formation.
Reference numeral 4 denotes a host computer which sends image data to the image forming apparatus 10 by a signal S7. Reference numeral 3 denotes a controller in the image forming apparatus 10 for expanding the sent image data. , To the control unit 21. Further, the control unit 21 receives the information of the recording paper size from the recording paper size sensor 114. The controller 3 sends the image clock signal S4 to the control unit 21 at the same time as S5. The recording paper transport controller 22 controls the recording paper transport by driving the motor 23 in response to the recording paper transport signal sent from the controller 21 by the signal S10. The motor 23 mechanically drives a roller 25 for conveying the recording paper. Reference numeral 107 denotes an optical unit that emits light in response to a laser ON / OFF signal sent from the control unit 21 based on the signal S11 and forms an image on the image carrier 100.

FIG. 7 shows an image clock (S4) and image data (S4) sent from the controller 3 during image formation.
5) and laser ON / OFF (S31) and recording paper 1
FIG. 3 is a diagram illustrating a relationship with a print image (main scanning direction) printed on the image No. 02. On the controller 3, the image data is transmitted at the falling edge of the image clock, and the control unit 21 receives the image data at the rising edge of the image clock, and sets ON / OFF of the laser based on the image data.

FIG. 8 is a flowchart showing the operation of the control unit 21 for controlling the image clock signal S4 and the conveyance of the recording paper.

When the power of the entire apparatus is turned on (ST30)
0), the image forming apparatus receives signals S4 and S from the controller 3;
5 (ST30).
1). This is mainly due to a waiting time such as warming up of the fixing unit.

The recording paper size sensor 114 detects the recording paper size (ST302). The controller 3 waits until the image signal S5 is transmitted (ST303). If the image signal S5 is transmitted (ST303-Yes), a recording paper conveyance command is transmitted to the recording paper conveyance control unit 22 by the signal S10 (ST3).
04).

The image clock signal S4 and the image signal S5
(ST305), and it is determined whether or not the transmission of the image data from the controller 3 has been completed (S305).
T306) When the processing is completed (ST306-Yes),
In response to signal S10, a recording paper conveyance stop command is sent to recording paper conveyance unit 22 (ST307).

If image formation has not been completed in step ST306 (ST306-No), the process returns to step ST305.

FIG. 9 is a flowchart showing the operation of the recording paper transport control unit 22. When the power is turned on (ST30
0), and waits until receiving the recording paper transport signal S10 from the control unit 21; after receiving (ST311-Yes), the motor 23 is rotated at a predetermined speed (ST312), and the recording paper transport stop signal S10 is transmitted from the control unit 21. It is determined whether or not it has been received (ST313), and if it has been received (ST31).
3-Yes), the motor 23 is stopped (ST314).

If the recording paper conveyance stop signal S10 has not been received in step ST313 (ST313).
-No), the process proceeds to step ST312.

FIG. 10 shows a conventional image forming apparatus in which a double-sided printing unit is mounted. In FIG. 10, 1
Reference numeral 15 denotes a duplex unit, and 116 denotes a paper path for recording paper.
Reference numeral 122 denotes a sensor for detecting a recording paper reversal timing. The recording paper 102 on which the image formation on the front side has been completed is conveyed to the duplex unit, and the trailing edge of the recording paper passes through the sensor 122, is folded back in the duplex unit, and again before the paper jam sensor 120. Transported to

FIG. 11 is a block diagram of a control system for conveying the recording paper of the duplex unit of the conventional apparatus. This figure shows only the control related to the recording paper conveyance of the duplex unit 114, and does not show other controls. Reference numeral 114 denotes a double-sided unit. The double-sided recording paper transport controller 125 uses the recording paper transport signal S19 sent from the controller 21 to
26, the driving direction of the motor 126 is controlled by the signal S22 from the reversing sensor 122, and the recording paper is conveyed. The motor 126 mechanically drives a roller 127 for conveying the recording paper.

[0014]

In the above-mentioned conventional example, the recording paper cannot be continuously conveyed to the duplex unit 115 during monocolor printing. This is because the motor must be reversed when the recording paper in the duplex unit is reversed, and the recording paper cannot be transported to the recording paper reversed portion of the duplex unit 115 during the reverse rotation of the motor. Therefore, after one sheet of recording paper is conveyed into the duplex unit, the end processing of the electrophotographic process is performed, and then printing of the recording paper is started again. The end process of the electrophotographic process requires about 15 to 20 seconds to clean the transfer belt and the like.

FIG. 12 is a flowchart (part 1) showing the operation of the control section 21 for controlling the recording paper conveyance during the monocolor double-sided conveyance. Here, only the sequence control is shown. Start double-sided mono-color printing (ST32)
0). An image is formed on a transfer belt (ST321), recording paper is fed from a cassette (ST322), and the image is transferred to the recording paper (ST323).

Next, the recording paper is transported to the duplex unit (ST).
324), the end processing of the electrophotographic process (cleaning of the transfer belt and the like) is performed (ST325), and the end of the processing is waited (ST326). Next, an image is formed on the transfer belt (ST327), recording paper is fed from the duplex unit (ST328), and the image is transferred to the recording paper (ST32).
9).

Next, the recording paper is conveyed to the main body discharge section (ST3).
30), the presence or absence of the next image is determined (ST331),
If there is a next image (ST331-Yes), ST3
Go to 21. If not (ST331-No), the end processing of the electrophotographic process (cleaning of the transfer belt, etc.)
(ST332), and waits for the end of the process (ST33).
3), end.

FIG. 13 shows a sequence and time for performing double-sided printing when one sheet of recording paper is conveyed into the double-sided unit. The left side shows the operation of the main body, and the right side shows the operation in the duplex unit. Here, T1 is the printing time when the paper is fed from the cassette, T2 is the printing time when printing from the duplex unit, and T3 is the time required for the electrophotographic process end processing. Here, T1 is the time required for the front side image formation and cassette feeding, T2 is the time required for the back side image formation and paper feeding, T3
Is the electrophotographic process end time as follows.

[0019]

(Equation 1)

TTH1 = T1 + T3 + T2 + T3.

Where T1 = 10 seconds, T2 = 10 seconds, T
If 3 = 20 seconds, TTH1 = 60 seconds. Similarly N
The throughput when printing sheets is

[0022]

(Equation 2)

TN1 = (T1 × N + T2 × N + T3 × N × 2) ÷ N = T1 + T2 + T3 × 2, which is constant regardless of the number of sheets.

FIG. 14 is a flowchart (part 2) showing the operation of the control section 21 for controlling the recording paper transport during the monocolor duplex transport. In this flowchart, printing of the back side is sequentially performed after two or more recording sheets are held in the duplex unit 115. Double-sided monocolor printing is started (ST340). An image is formed on the transfer belt (ST341), and recording paper is fed from a cassette (ST3).
42), the image is transferred to the recording paper (ST343). Next, the recording paper is transported to the duplex unit (ST344), and the electrophotographic process is terminated (cleaning of the transfer belt, etc.).
(ST345), and waits for the end of the process (ST34).
6). If it is determined that the sheet can be further fed into the duplex unit (ST347), the process proceeds to ST341. Next, an image is formed on the transfer belt (ST348), recording paper is fed from the duplex unit (ST349), and the image is transferred to the recording paper (ST350). Next, the recording paper is conveyed to the main body discharge section (ST351), and the presence or absence of the next image is determined (ST351).
352) If there is a next image, the process goes to ST341.
If there is not, the end process of the electrophotographic process (cleaning of the transfer belt and the like) is performed (ST353), and the process is waited for (ST354), and the process ends.

FIG. 15 shows a sequence and time for performing double-sided printing when two recording sheets are conveyed into the double-sided unit. The left side shows the operation of the main body, and the right side shows the operation in the duplex unit. Here, when this operation is repeated, assuming that the throughput per sheet is T1, the time required for front side image formation and cassette feeding, T2 is the time required for back side image formation and paper feeding, and T3 is the electrophotographic process end time. It looks like this:

[0026]

(Equation 3)

TTH2 = (T1 + T3 + T1 + T3 + T2
+ T2 + T3) ÷ 2.

Here, T1 = 10 seconds, T2 = 10 seconds, T
If 3 = 20 seconds, TTH2 = 50 seconds. The throughput when printing N sheets is

[0029]

(Equation 4)

TN2 = (T1 × N + T2 × N + T3 × (N + 1))) ÷ N = T1 + T2 + T3 + T3 / N After one sheet of recording paper is conveyed to the double-sided unit in this way, in order to surely end the electrophotographic process,
The influence of T3 remains in the recording paper discharge throughput regardless of the number of sheets.

[0031]

Means for Solving the Problems To solve the above problems, the present invention comprises the following constitutions.

That is, an image forming apparatus capable of transmitting and receiving double-sided printing information and printing on both sides of a recording sheet with minimum throughput is provided by an image forming means for forming an image based on the printing information, A cassette feeding means for feeding the recording paper for transfer, a duplex unit transport means for transporting the recording paper to a duplex unit for duplex printing after transferring the image, and performing duplex printing Control means for sending out predetermined blank data and an image clock from the number of sheets and the number of sheets that can be conveyed to the duplex unit, and the image forming means further comprises: A blank image is formed from blank data and the image clock, and after the back side image is formed, both sides for feeding the recording paper from the duplex unit for back side printing. Comprising a unit feeding means.

If the control means determines that it is not time to perform the back side printing, it sends a blank printing prohibition signal to omit the blank image formation.

Also, an image forming method capable of transmitting and receiving double-sided printing information and printing on both sides of a recording sheet with a minimum throughput includes an image forming step of forming an image based on the printing information, and A cassette feeding step for feeding the recording paper for transfer, a duplex unit transporting step for transporting the recording paper to a duplex unit for duplex printing after the image transfer, and a duplex printing are performed. The control step of transmitting predetermined blank data and an image clock from the number of sheets and the number of sheets that can be conveyed to the double-sided unit, and the image forming step further includes the steps of: A blank image is formed from the blank data and the image clock, and after forming the back side image, a duplex unit for feeding the recording paper from the duplex unit for back side printing. Tsu comprising a preparative feeding step.

If the control step determines that it is not in time for the printing of the back side, a blank print prohibition signal is transmitted to omit the formation of the blank image.

An image forming means for forming an image based on print information; a cassette paper feeding means for feeding the recording paper for transferring the formed image; A duplex unit transport unit for transporting paper to a duplex unit for duplex printing, and a control unit for transmitting predetermined blank data and an image clock from the number of sheets to be duplexed and the number of sheets transportable to the duplex unit. And the image forming means further forms a blank image from the blank data and the image clock in order to synchronize with the completion of paper feed preparation for back printing, and after the back image is formed, the blank image is formed for back printing. A duplex unit paper feeding means for feeding the recording paper from the duplex unit, and a computer-readable recording program for causing the computer to function. Comprising a capacity recording medium.

An image forming apparatus capable of transmitting and receiving double-sided printing information and printing on both sides of a recording sheet with a minimum throughput includes an image forming means for forming an image based on the printing information, A cassette feeding means for feeding the recording paper for transfer, a duplex unit transport means for transporting the recording paper to a duplex unit for duplex printing after transferring the image, and performing duplex printing The printer engine means for transmitting predetermined blank data and an image clock based on the number of sheets and the number of sheets that can be conveyed to the duplex unit, and the image forming means further include: A blank image is formed from the blank data and the image clock, and after the back side image is formed, both sides for feeding the recording paper from the duplex unit for back side printing. And a unit feeding means.

An image forming method capable of transmitting and receiving double-sided printing information and printing on both sides of a recording sheet with a minimum throughput includes an image forming step of forming an image based on the printing information, and A cassette feeding step for feeding the recording paper for transfer, a duplex unit transporting step for transporting the recording paper to a duplex unit for duplex printing after the image transfer, and a duplex printing are performed. The printer engine step of sending out predetermined blank data and an image clock from the number of sheets and the number of sheets that can be conveyed to the duplex unit, and the image forming step are further performed in order to synchronize with the completion of sheet preparation for backside printing. A blank image is formed from the blank data and the image clock, and after the back side image is formed, both sides for feeding the recording paper from the duplex unit for back side printing. And a unit feeding step.

[0039]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment A first embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a flow chart showing the operation of the control section 1 for controlling the recording paper conveyance during mono-color double-sided conveyance. In this flowchart, after the recording paper is conveyed to the duplex unit, the duplex printing is performed without performing the electrophotographic process end processing. Double-sided monocolor printing is started (ST200). An image is formed on a transfer belt (ST201), and recording paper is fed from a cassette (ST2).
02), the image is transferred to the recording paper (ST203). Next, the recording paper is conveyed to the duplex unit (ST204), and blank data printing is performed (ST205). If it is determined that paper can be further fed into the duplex unit (ST206-Ye
s) Go to ST201. Next, an image is formed on the transfer belt (ST207), recording paper is fed from the duplex unit (ST208), and the image is transferred to the recording paper (ST2).
09).

Next, the recording paper is conveyed to the main body discharge section (ST2).
10), the presence or absence of the next image is determined (ST211),
If there is a next image (ST211-Yes), ST2
Go to 12. If there is not (ST211-No), the end processing of the electrophotographic process (cleaning of the transfer belt, etc.)
(ST213), and waits for the end of the process (ST21).
4), end.

In ST212, it is determined from which sheet is to be fed next, and if it is a double-sided unit, the process goes to ST207 (ST212-No), and if it is a cassette (ST21-NO).
2-Yes), go to ST201. Here, when printing blank data, the feeding operation of the recording paper is not performed.

FIG. 2 shows a sequence and time for performing double-sided printing when three recording sheets are conveyed into the double-sided unit. The left side shows the operation of the main body, and the right side shows the operation in the duplex unit. If T1 is the time required for front side image formation and cassette feeding, T2 is the time required for back side image formation and paper feeding, T3 is the electrophotographic process end time, and T4 is the printing time for blank image formation, the throughput per sheet is , As follows.

[0044]

(Equation 5)

TTH = (T1 + T4 + T1 + T4 + T1 +
T2 + T2 + T2 + T3) ÷ 3, T1 = 10 seconds, T2
= 10 seconds, T4 = 10 seconds, T3 = 20 seconds, TTH
= About 33 seconds. Here, when repeating this operation,
The throughput when printing N sticks is

[0046]

(Equation 6)

TN = (T1 × N + T2 × N + T4 × 2 + T3))) ÷ N = T1 + T2 + (T4 × 2 + T3) / N When the number N = ∞, TN = T1 + T2 converges, which is faster than conventional throughputs TN1 and TN2.

<Effects of First Embodiment> In general, in an image forming apparatus that performs an electrophotographic process, T3 is the electrophotographic process end time, T1 is the time required for front side image formation and cassette feeding, and T2 is the back side. The time required for image formation and paper feeding,
If T4 is the time required for blank image formation,

[0049]

(Equation 7)

Since T3> T1 = T2 = T4, instead of carrying out one electrophotographic process to the double-sided unit and terminating the electrophotographic process, a blank image is formed for printing the back side. By synchronizing with the completion of paper feed preparation, it is possible to improve (shorten) the throughput of recording paper discharge.

<Second Embodiment> FIG. 3 is a block diagram of a control system for image formation and recording paper transport of the apparatus of the second embodiment. FIG. 1 is a block diagram showing only controls related to image formation and recording paper conveyance, and does not show other controls. Reference numeral 10 denotes an image forming apparatus. The control unit 1 receives an image clock signal and an image signal from the controller 3 and emits a laser beam for conveying a recording sheet and forming an image.
Is a host computer that sends image data in response to the signal S7.

Reference numeral 3 denotes a controller in the image forming apparatus 10 for expanding the transmitted image data. The controller 3 transmits the expanded image data to the control unit 1 in S5. Further, the control unit 1 receives information on the recording paper size from the recording paper size sensor 114. The controller 3 sends the image clock signal S4 to the control unit 1 at the same time as S5.

The controller 3 sends a blank print inhibit signal S9 to the control unit 1. Recording paper transport control unit 22
Drives the motor 23 in accordance with the recording paper transport signal sent from the control unit 1 by the signal S10, and controls the transport of the recording paper. The motor 23 includes rollers 25 for transporting the recording paper.
Is driven mechanically. 107 is a signal S1 from the control unit 1.
An optical unit that emits light in response to the laser ON / OFF signal sent by the device 1 and forms an image on the image carrier 100.

Here, the blank print prohibition signal S9 is sent out when the controller 3 determines that it is not in time for the next image to be printed due to the image development time from the host computer. This makes it possible to omit a useless blank printing operation.

FIG. 4 shows an image clock (S4), image data (S5), and laser ON / OFF (S31) at the time of image formation sent from the controller 3, and a print image (S31) to be printed on the recording paper 102. FIG. On the controller 3, the image data is transmitted at the falling edge of the image clock, and the control unit 1 receives the image data at the rising edge of the image clock, and sets ON / OFF of the laser based on the received image data. In this figure, blank data is transmitted, and the blank data is transmitted by the controller 3. When the number of printed sheets is small, the effect of blank printing may be small. In this case, processing for omitting blank image formation is performed, and the controller 3 performs blank image formation so as to minimize throughput. It is possible to perform double-sided printing with a minimum throughput by judging whether or not to perform printing.

<Effects of the Second Embodiment> When the control means sends out blank data and determines that forming a blank image by the image forming means is not in time for backside printing, the control means outputs the blank image. A blank print prohibition signal is sent in order to omit printing, and by switching the control mode, it is possible to perform double-sided printing while maintaining a minimum throughput.

<Third Embodiment> In the first and second embodiments, the controller 3 sends out the image clock and the predetermined blank data.
However, the present invention is not limited to this. It is also possible to send the image clock and predetermined blank data on the printer engine side (not shown). Printer engine (driver)
Is software located between the higher-level operation software and the printer. It reprocesses the data passed from the higher-level software into data that allows the printer to operate correctly, and sends the data to the printer. .

In this case, an image forming apparatus capable of transmitting and receiving double-sided printing information and printing on both sides of the recording paper with a minimum throughput is provided by an image forming means for forming an image based on the printing information; Cassette feeding means for feeding the recording paper for transferring the image, a duplex unit conveying means for conveying the recording paper to a duplex unit for duplex printing after transferring the image, and duplex printing. The printer engine means for transmitting predetermined blank data and the image clock based on the number of sheets to be conveyed and the number of sheets that can be conveyed to the duplex unit, and the image forming means further synchronize with the completion of sheet feeding preparation for backside printing. To form a blank image from the blank data and the image clock, and to feed the recording paper from the duplex unit for backside printing after backside image formation. And a duplex unit feeding means.

Further, an image forming method capable of transmitting and receiving double-sided printing information and printing on both sides of a recording sheet with a minimum throughput includes: an image forming step of forming an image based on the printing information; A cassette feeding step for feeding the recording paper for transfer, a duplex unit transporting step for transporting the recording paper to a duplex unit for duplex printing after the image transfer, and a duplex printing are performed. The printer engine step of sending out predetermined blank data and an image clock from the number of sheets and the number of sheets that can be conveyed to the duplex unit, and the image forming step are further performed in order to synchronize with the completion of sheet preparation for backside printing. A blank image is formed from the blank data and the image clock, and after the back side image is formed, both sides for feeding the recording paper from the duplex unit for back side printing. It will be provided with the unit feeding step.

Alternatively, the computer-readable recording medium includes image forming means for forming an image based on print information, cassette feeding means for feeding the recording paper for transferring the formed image, After transferring the image, a double-sided unit conveying means for conveying the recording paper to the double-sided unit for double-sided printing, a predetermined number of double-sided prints, and predetermined blank data based on the number of conveyable sheets to the double-sided unit. A printer engine means for transmitting an image clock, and the image forming means further forms a blank image from the blank data and the image clock for synchronizing with the completion of paper feed preparation for backside printing, A program for causing a duplex unit paper feed unit to feed the recording paper from the duplex unit for backside printing after formation It made what was recorded.

Even if the image clock and the blank data are sent out by the printer engine unit instead of the controller 3, as in the case of the first embodiment, one sheet of recording paper is conveyed to the duplex unit, and then the electrophotographic process is started. Instead of performing the end processing, by forming a blank image and synchronizing with the completion of paper feed preparation for back side printing, it is possible to improve (shorten) the throughput of recording paper discharge. If the printer engine unit sends out blank data and determines that forming a blank image by the image forming unit is not in time for backside printing, a blank print prohibition signal is used to omit the blank image formation. And by switching the control mode, it is possible to perform double-sided printing while maintaining a minimum throughput.

[0062]

[Other Embodiments] Even if the present invention is applied to a system including a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), an apparatus (for example, a copying machine) Machine, facsimile machine, etc.).

Another object of the present invention is to supply a storage medium storing program codes of software for realizing the functions of the above-described embodiments to a system or an apparatus, and to provide a computer (or CPU) of the system or the apparatus.
And MPU) read and execute the program code stored in the storage medium.

In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiment, and the storage medium storing the program code constitutes the present invention.

As a storage medium for supplying the program code, for example, a floppy disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD
-R, a magnetic tape, a nonvolatile memory card, a ROM, or the like can be used.

When the computer executes the readout program code, not only the functions of the above-described embodiment are realized, but also an OS (Operating System) running on the computer based on the instruction of the program code. ) May perform some or all of the actual processing, and the processing may realize the functions of the above-described embodiments.

Further, after the program code read from the storage medium is written into a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, based on the instructions of the program code, It goes without saying that the CPU included in the function expansion board or the function expansion unit performs part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.

When the present invention is applied to the storage medium, the storage medium stores program codes corresponding to the above-described flowcharts. Each module shown will be stored in a storage medium. That is, if the program codes of at least the modules of the “image forming module 1601”, the “cassette feeding module 1602”, the “duplex unit transport module 1603”, the “control module 1604”, and the “duplex unit feeding module 1605” are stored in the storage medium. Good.

[0069]

As described above, the image forming apparatus according to the present invention transmits and receives double-sided printing information, and the control means controls the number of double-sided printings and the double-sided printing paper that holds the recording paper that has been evacuated after printing on the front side. Based on the number of sheets that can be conveyed to the unit, predetermined blank data and an image clock are sent to the image forming means. Upon receiving this data, the image forming unit forms a blank image in order to synchronize with the completion of paper feed preparation for backside printing, and adjusts the timing.After forming the backside image with the image forming unit, the image forming unit performs the backside printing. The recording paper is fed from a duplex unit. By generating dummy print data (blank image) and performing control to match the timing of image formation on the front side and preparation for paper feeding on the back side, it is possible to improve (shorten) the recording paper discharge throughput. And
This effect increases as the number of continuous duplex printing increases.

[0070]

[Brief description of the drawings]

FIG. 1 is a flowchart of a first embodiment.

FIG. 2 is a diagram illustrating an operation sequence of the image forming apparatus according to the first exemplary embodiment.

FIG. 3 is a block diagram of control according to a second embodiment.

FIG. 4 is a diagram illustrating a relationship between an image clock and image data transmitted from a controller according to a second embodiment and a print image printed on a recording sheet.

FIG. 5 is a sectional view of a conventional image forming apparatus main body.

FIG. 6 is a block diagram showing a conventional control system.

FIG. 7 is a diagram showing a relationship between an image clock and image data sent from a conventional controller and a print image printed on recording paper.

FIG. 8 is a flowchart of the operation of a control unit in a conventional example.

FIG. 9 is a flowchart showing a conventional example of control unit driving.

FIG. 10 is a cross-sectional view of a conventional apparatus when a duplex unit is mounted.

FIG. 11 is a block diagram of a control system when a double-sided unit of the related art is mounted.

FIG. 12 is a flowchart (part 1) of a conventional example.

FIG. 13 is a diagram (part 1) illustrating an operation sequence of the conventional image forming apparatus.

FIG. 14 is a flowchart (part 2) of a conventional example.

FIG. 15 is a diagram (part 2) illustrating an operation sequence of the conventional image forming apparatus.

FIG. 16 is a diagram illustrating a memory map of a recording medium according to the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Control part 3 Controller 4 Host computer 22 Recording paper conveyance control part 23 Motor 100 Image carrier 107 Optical unit 115 Duplex unit 114 Paper size sensor 122 Inversion sensor 125 Double-sided recording paper conveyance control part 127 Double-sided recording conveyance part

Claims (7)

[Claims] 1. An image forming apparatus capable of transmitting and receiving double-sided printing information and printing on both sides of a recording sheet with a minimum throughput, comprising: an image forming means for forming an image based on the printing information; Cassette feeding means for feeding the recording paper for transferring an image; duplex transfer means for transporting the recording paper to a duplex unit for duplex printing after transferring the image; and duplex printing. Control means for transmitting predetermined blank data and an image clock based on the number of sheets to be conveyed and the number of sheets that can be conveyed to the double-sided unit. The image forming means further includes Forming a blank image from the blank data and the image clock; and forming a blank image from the duplex unit after the back side image is formed. An image forming apparatus comprising: a unit feeding means. 2. The apparatus according to claim 1, wherein said control means sends a blank print prohibition signal in order to omit formation of said blank image when judging that it is not time to perform said back side printing. The image forming apparatus as described in the above. 3. An image forming method capable of transmitting and receiving double-sided printing information and printing on both sides of a recording sheet with a minimum throughput, comprising: an image forming step of forming an image based on the printing information; A cassette feeding step for feeding the recording paper to transfer an image; a duplex unit transporting step for transporting the recording paper to a duplex unit for duplex printing after transferring the image; The control step of sending predetermined blank data and an image clock based on the number of sheets to be conveyed and the number of sheets that can be conveyed to the double-sided unit. Forming a blank image from the blank data and the image clock; and forming a blank image from the duplex unit after the back side image is formed. Image forming method characterized by comprising a unit feeding step. 4. The method according to claim 1, wherein the control step sends a blank print prohibition signal to omit the formation of the blank image when it is determined that it is not time to perform the back side printing. The image forming method as described in the above. 5. An image forming means for forming an image based on print information, a cassette paper feeding means for feeding the recording paper for transferring the formed image, and the recording after transferring the image. A duplex unit transport unit for transporting paper to a duplex unit for duplex printing, a control unit for sending predetermined blank data and an image clock from the number of sheets to be duplexed and the number of sheets transportable to the duplex unit The image forming means further forms a blank image from the blank data and the image clock in order to synchronize with the completion of paper feed preparation for back printing, and after the back image is formed, the blank image is formed for back printing. A duplex unit feeding means for feeding the recording paper from the duplex unit; and a computer readable recording program for causing a computer to function as Do recording medium. 6. An image forming apparatus capable of transmitting and receiving double-sided printing information and printing on both sides of a recording sheet with a minimum throughput, comprising: an image forming means for forming an image based on the printing information; Cassette feeding means for feeding the recording paper for transferring an image; duplex transfer means for transporting the recording paper to a duplex unit for duplex printing after transferring the image; and duplex printing. Printer engine means for sending predetermined blank data and an image clock from the number of sheets to be conveyed and the number of sheets that can be conveyed to the duplex unit; and the image forming means further synchronizes with the completion of sheet feeding preparation for backside printing. To form a blank image from the blank data and the image clock, and to feed the recording paper from the duplex unit for backside printing after backside image formation. An image forming apparatus comprising: the duplexer feeding means. 7. An image forming method capable of transmitting and receiving double-sided printing information and printing on both sides of a recording paper with a minimum throughput, comprising: an image forming step of forming an image based on the printing information; A cassette paper feeding step for feeding the recording paper to transfer an image; a duplex unit transporting step for transporting the recording paper to a duplex unit for duplex printing after the image transfer; The printer engine step of transmitting predetermined blank data and an image clock from the number of sheets to be conveyed and the number of sheets that can be conveyed to the double-sided unit. The image forming step further synchronizes with the completion of sheet feeding preparation for backside printing. To form a blank image from the blank data and the image clock, and to feed the recording paper from the duplex unit for backside printing after backside image formation. Image forming method comprising: the duplexer feeding step.