JPH11219074A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the reproducibility of a digital copying machine which adopts a both-side printing procedure by automatically switching a 2nd printing procedure for the both-side printing of priority images to a 1st printing procedure at the time of priority image selection only when nonpriority images are printed on both surfaces. SOLUTION: A printing procedure switching means selects the 1st printing procedure for preventing the number of recording sheets in a print part 26 and a paper refeed part 34 from exceeding the number of refed paper standby positions when both-side printing is specified and the 2nd printing procedure for making the number of the recording sheets in the print part 26 and paper refeed part 34 larger than the number of refed paper standby positions. A selecting means for priority image can select images given priority when pieces of image data are read in at the same time. A control means automatically switches the 2nd printing procedure for the both-side printing of the priority images to the 1st printing procedure at the time of the priority image selection only when nonpriority images are printed on both surfaces.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a digital copying machine, and more particularly to an image forming apparatus with improved productivity.

[0002]

2. Description of the Related Art Conventionally, a digital copying machine usually has not only a copy function but also a printer function, and one image is input for a plurality of image inputs (a scanner image for copy, an image from a host computer for printer). The output (printing) section is shared. As described above, a digital copying machine having a plurality of image inputs generally has a function of selecting one of the images as a priority image and outputting the image preferentially.

In a relatively large digital copying machine,
In order to improve the productivity, a printing procedure is adopted in which the number of recording sheets in the printing unit and the re-feeding unit becomes larger than the number of standby positions during duplex printing.

However, if priority image control is performed during double-sided printing in the above printing procedure, the following problems occur.

A problem in a case where a control method for selecting a priority image at the time of double-sided printing will be described with reference to FIG. FIG.
In the conventional printing procedure (c), the first surface (C1) of the first recording sheet, the first surface (C3) of the second recording sheet,
First surface of the third recording sheet (C5), second surface of the first recording sheet (C2), first surface of the fourth recording sheet (C7), first priority image (P1) It should be printed in the order of the second priority image (P2), the third priority image (P3), and the fourth priority image (P4). Thrust into a rear-end collision.

That is, in the case where double-sided printing is performed by using the second printing procedure which is highly productive with a non-priority image (the time required for a certain printing operation to be completed is short), the priority image (P1) When (P4) interrupts, during output of the priority image,
The recording sheets (C3) and (C5) are in a standby state in the re-feed section, and the recording sheet (C7) enters the recording sheet and a jam occurs. Therefore, in a digital copying machine employing such a double-sided printing procedure, a control method for selecting a priority image, that is, a priority image control method cannot be taken.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus in which a priority image can be selected when a plurality of images are input in a digital copying machine employing a double-sided printing procedure, thereby improving productivity. And

[0007]

According to another aspect of the present invention, there is provided an image forming apparatus, comprising: a writing unit for writing an electrostatic latent image on a photosensitive member based on image data; A selector for selectively reading any one of them, and outputting the readout to a writing unit, a printing unit for developing the electrostatic latent image and transferring it to a recording sheet before printing,
A paper feeding unit that transports the recording sheet before printing to the printing unit, a re-feeding unit that reverses the recording sheet with one side printed when two-sided printing is specified and transports it to the printing unit again, and a two-sided printing The refeeding standby position where the recording sheet with one side printed is waiting for refeeding if specified, and the number of recording sheets in the printing section and refeeding section when duplex printing is specified. Printing for selecting a first printing procedure for preventing the number of standby positions from being exceeded and a second printing procedure for ensuring that the number of recording sheets in the printing unit and the re-feeding unit is larger than the number of re-feeding standby positions. A procedure switching unit, a priority image data selecting unit that can select priority image data when a plurality of image data are read at the same time, and a first printing procedure for duplex printing of priority image data. The second printing method is used for duplex printing of priority image data. It is characterized in that a control means for controlling to select. In this configuration,
The priority image can be printed with the highest priority. Especially,
It is suitable for printing of priority images frequently.

According to a second aspect of the present invention, there is provided an image forming apparatus, comprising: a writing unit for writing an electrostatic latent image on a photosensitive member based on image data; and selectively reading one of a plurality of read image data. A printing unit for developing the electrostatic latent image and transferring it to a recording sheet before printing; a paper feeding unit for transporting the recording sheet before printing to the printing unit; In the case where the recording sheet on which one side is printed is reversed and the sheet is reversed and then conveyed to the printing section again, and in the case of double-sided printing designation, the recording sheet on which one side is printed waits for re-feeding The first printing procedure and the inside of the printing unit and the re-feeding unit so that the number of recording sheets in the printing unit and the re-feeding unit does not exceed the number of waiting positions in the re-feeding unit and the printing unit and the re-feeding unit when duplex printing is specified. The number of recording sheets is less than the number of refeed standby positions. A printing procedure switching means for selecting a second printing procedure to increase the number of printing data, a selecting means for selecting priority image data which can select a priority image data when a plurality of image data are read at the same time; Control means for performing non-priority image data double-sided printing in the second printing procedure and controlling so as to inhibit interruption of priority image data during double-sided printing. With this configuration, double-sided printing with high productivity can be performed. This is suitable when the frequency of use of the non-priority image is high but the number of sheets output at one time is small.

According to a third aspect of the present invention, there is provided an image forming apparatus for writing an electrostatic latent image on a photosensitive member based on image data, and selectively reading one of a plurality of read image data. A printing unit for developing the electrostatic latent image and transferring it to a recording sheet before printing; a paper feeding unit for transporting the recording sheet before printing to the printing unit; In the case where the recording sheet on which one side is printed is reversed and the sheet is reversed and then conveyed to the printing section again, and in the case of double-sided printing designation, the recording sheet on which one side is printed waits for re-feeding The first printing procedure and the inside of the printing unit and the re-feeding unit so that the number of recording sheets in the printing unit and the re-feeding unit does not exceed the number of waiting positions in the re-feeding unit and the printing unit and the re-feeding unit when duplex printing is specified. The number of recording sheets is less than the number of refeed standby positions. A printing procedure switching means for selecting a second printing procedure for increasing the number of image data, a priority image data selecting means for selecting priority image data when a plurality of image data are read at the same time; Control means for controlling to select the first printing procedure for duplex printing of image data and to select the second printing procedure for duplex printing of non-priority image data;
It is characterized in that double-sided printing is performed in a printing procedure, and control means for controlling interruption of priority image data is inhibited during double-sided printing. In this configuration, both-sided printing with high productivity can be performed, and when the priority image is frequently printed, the priority image can be printed with the highest priority. Suitable for small cases.

According to another aspect of the present invention, there is provided an image forming apparatus for writing an electrostatic latent image on a photosensitive member based on image data, and selectively reading one of a plurality of read image data. A printing unit for developing the electrostatic latent image and transferring it to a recording sheet before printing; a paper feeding unit for transporting the recording sheet before printing to the printing unit; In the case where the recording sheet on which one side is printed is reversed and the sheet is reversed and then conveyed to the printing section again, and in the case of double-sided printing designation, the recording sheet on which one side is printed waits for re-feeding The first printing procedure and the inside of the printing unit and the re-feeding unit so that the number of recording sheets in the printing unit and the re-feeding unit does not exceed the number of waiting positions in the re-feeding unit and the printing unit and the re-feeding unit when duplex printing is specified. The number of recording sheets is less than the number of refeed standby positions. A printing procedure switching means for selecting a second printing procedure for increasing the number of image data, a means for selecting priority image data which can select priority image data when a plurality of image data are read at the same time; Control means for performing double-sided printing of the priority image data in the second printing procedure, and controlling to permit printing of non-priority image data only on the second side even after the priority image data is interrupted. I have. With this configuration, even after the priority image is interrupted during duplex printing of the non-priority image, interruption can be permitted only on the second side of the non-priority image.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. First, a digital copying machine as an example of an image forming apparatus to which the present invention is applied will be described with reference to FIG.

FIG. 1 is a diagram for explaining a digital copying machine as an example of an image forming apparatus to which the present invention is applied. A contact glass 2 is provided on the upper surface of the image forming apparatus 1, and a document holder 4 having an automatic document feeder 3 is provided thereon. Below the contact glass 2, a reading unit 5 as an image input unit is provided.

The automatic document feeder 3 includes a document table 6, a document set detection sensor 7, a feed roller 8, a feed belt 9
And a discharge roller 10 and a paper discharge table 11. The document table 6 is inclined, and a document bundle is placed on the document table 6 with the image surface facing upward. When the bundle of originals is placed at the correct position, the original set detection sensor 7 recognizes the presence of the original, and the original can be fed. When the operator presses a start button (not shown), the uppermost sheet of the document bundle placed on the document table 6 is pulled out by the feed roller 8 and sent to a predetermined position of the contact glass 2 by the feed belt 9. When the image of the document is read by the reading unit 5, the document is sent again by the feed belt 9, and is discharged to the discharge table 11 by the discharge roller 10.

The reading unit 5 includes the first scanning unit 1
2, a second scanning unit 13, a lens 14, and a CCD image sensor 15. First scanning unit 12
Is composed of an exposure lamp 16 for exposing the original on the contact glass 2 and a first mirror 17 for guiding the light reflected by the original to the second scanning unit 13, and moves along the contact glass 2. The second scanning unit 13 has a second mirror 18 and a third mirror 19. Second scanning unit 1
3 moves the scanning speed of the first scanning unit 12 at half the scanning speed so that the distance between the first scanning unit 12 and the CCD image sensor 15 is kept constant during the scanning of the first scanning unit 12. The light reflected by the first mirror 17 is guided to the CCD image sensor 15 by the second mirror 18 and the third mirror 19. The magnification of the image to be formed is changed by moving the lens 14 and the CCD image sensor 15 in parallel in the scanning direction.

The image data read by the CCD image sensor 15 is sent to a laser output unit 21 included in the writing unit 20. The writing unit 20 includes a laser output unit 21, an imaging lens 22, and a mirror 2
3 are provided. Although not shown, the laser output unit 21 is provided with a laser diode and a polygon mirror, and the polygon mirror is rotated at a high speed by a motor at a constant speed. The laser diode emits a laser beam based on the image data sent from the CCD image sensor 15, and the laser beam is deflected by a polygon mirror and output from a laser output unit 21. The output laser light passes through the imaging lens 22 and is reflected by the mirror 23.
And is condensed and imaged on the surface of the photoconductor 24.

A developing unit 25, a charging device (not shown), a cleaning unit, and the like are provided around the photoconductor 24, and a printing unit 26 is formed. An electrostatic latent image is written on the photoconductor 24 uniformly charged by the charging device by the laser light output from the laser output unit 21. The laser beam is deflected by a rotating polygon mirror to expose and scan the photoconductor 24 in a main scanning direction orthogonal to a sub-scanning direction, which is a rotation direction of the photoconductor 24, and to record image signals in line units. I do.

In the scanning area of the laser beam, the photosensitive member 24
Although not shown in the figure, an optical sensor is provided in the vicinity. When a laser beam is detected by the optical sensor, a synchronization signal is issued for synchronization in the main scanning direction. Image recording start timing control in the main scanning direction is performed based on the synchronization signal.

The exposure along the main scanning direction is repeated at a predetermined cycle corresponding to the rotation speed of the photosensitive member 24 and the recording density. This electrostatic latent image is developed by the developing device 25, and a toner image is formed on the surface of the photoconductor 24.

The toner image is transferred to a recording sheet (not shown) which is conveyed by the conveyor belt 27. Conveyor belt 27
Moves at the same speed as the moving speed of the outer peripheral surface of the photoconductor 24. The recording sheets are stored by size in a tray 29 of a sheet feeding unit 28 which is a plurality of sheet feeding units provided in a lower portion of the image forming apparatus 1. Sent to The recording sheet S is stored in the tray 29 of each sheet feeding unit 28 for each size.

The toner image transferred to the recording sheet is fixed on the recording sheet by a fixing unit 31,
Is selectively conveyed to the discharge tray 33 or the re-feed unit 34 which is a re-feed unit. The paper discharge unit 32
When the branch claw 35 is at the position shown by the solid line, the recording sheet is discharged to the paper discharge tray 33, and when the branch claw 35 is at the position shown by the two-dot chain line, the recording sheet is provided. Is sent to the re-feed unit.

The re-feeding unit 34 is for reversing a recording sheet on which one side has been printed and re-feeding the sheet when double-sided printing is designated. The first and second standby positions 37 and 38, which are two re-feed standby positions, are provided. When double-sided printing is designated, the recording sheet having the toner image fixed on one side first enters the reversing conveyance path 36, is reversed, and is fed again at the first standby position 37 and the second standby position 38.

The paper feeding unit 28 or the paper re-feeding unit 34
The recording sheet conveyed from the printer is sent from the registration roller 39 located on the upstream side of the photoconductor 24 to the printing unit 26 at the same time as reading the image data, and the toner image on the surface of the photoconductor 24 and printing of the recording sheet are performed. Is adjusted.

Next, a printing procedure in such a digital copying machine will be described with reference to FIG. FIG. 7 is a diagram showing an image writing procedure and its time. FIG.
In, the numbers in the squares indicate pages. For example, the first surface of the first recording sheet is C1 and the second surface is C2. The horizontal axis represents the flow of time. In the present embodiment, it is assumed that the standby position of the re-feeding unit is two. After printing on the first side, the time from when the sheet reaches the re-feeding unit via the transport path to when the second side is printed is t. Since this transport path is long, it is effective to feed more sheets on the transport path than the re-feed standby position to improve productivity.

This point is shown in FIGS. 7 (a) and 7 (b). This is a printing of 12 pages of 6 recording sheets. FIG. 7A is a diagram illustrating a first printing procedure. As such a printing procedure, a first printing procedure shown in FIG. FIG.
In the first printing procedure (a), the first printing sheet
Surface (C1), the first surface (C3) of the second recording sheet, 1
The second surface of the second recording sheet (C2), the first surface of the third recording sheet (C5), the second surface of the second recording sheet (C2)
4) First surface of the fourth recording sheet (C7), second surface of the third recording sheet (C6), first surface of the fifth recording sheet (C9), fourth recording The second side of the sheet (C8),
The first surface (C11) of the sixth recording sheet, the second surface (C10) of the fifth recording sheet, the second surface of the sixth recording sheet
Printing is performed in the order of the surface (C12). This first printing procedure is:
This is a printing procedure for preventing the number of recording sheets in the printing unit and the re-feeding unit from exceeding the number of standby positions.

FIG. 7B shows the second printing procedure. As such a printing procedure, the second printing shown in FIG.
A printing procedure is conceivable. In the second printing procedure of FIG. 7B, the first surface (C1) of the first recording sheet, the first surface (C3) of the second recording sheet, and the first surface of the third recording sheet
Surface (C5), second surface (C2) of the first recording sheet, 4
The first surface (C7) of the second recording sheet, the second surface (C4) of the second recording sheet, the first surface (C
9) The second surface (C6) of the third recording sheet, the first surface (C11) of the sixth recording sheet, the second surface (C8) of the fourth recording sheet, and the fifth recording The second side of the sheet (C1
0), and printing is performed in the order of the second surface (C12) of the sixth recording sheet. This second printing procedure is a printing procedure in which the number of recording sheets in the printing unit and the re-feeding unit is larger than the number of standby positions.

It can be seen that the time until the end is higher in the first printing procedure and higher in the second printing procedure with Tb and Ta in the second printing procedure. As described above, in a large-sized digital copying machine having a relatively long conveying path as in the embodiment, the method of the second printing procedure is employed in order to improve productivity in double-sided printing.

Next, the priority image at the time of image output will be described. FIG. 2 is a block diagram for selecting image data from a plurality of image input means and outputting it to a writing unit. As shown in FIG. 2, in the digital copying machine of the present invention,
An external device 43 such as a host computer for transferring data to the printer controller 42; a printer controller 42 for expanding the data transferred from the external device 43 into image data; and an image reading device 44 for reading the image data
(Reading unit 5), an image memory 45 for storing the read image, and a selector for selectively reading any one of a plurality of image data read by a plurality of image input means and outputting to the writing unit 20. 41, and a writing unit 20 for writing an electrostatic latent image on the photoconductor 24 based on image data.

In a digital copying machine, as shown in FIG.
When printing the image data read by the image reading device as it is, temporarily storing the read image in the image memory and printing the image data in the image memory, the data transferred from the external device such as the host computer is printed by the printer controller. There are a plurality of image data supply sources, for example, when the image data is developed and printed.

Further, when there are a plurality of image data supply sources, a control method is adopted in which the user selects the priority image and does not interrupt the non-priority image when the priority image is continuously supplied. May be This is the case, for example, when a user who frequently uses copy waits for a long time if a printer image via a network is interrupted while waiting for the end of copying in front of the apparatus, so that the copy image is prioritized to prevent this. is there.

FIG. 3 is a flowchart showing the control of the priority image. As shown in FIG. 3, first, in step S1, it is determined whether or not there is a request for writing a priority image.
When there is a write request, the process proceeds to step S2, and when there is no write request, the process proceeds to step S3.

Next, in step S2, writing control of priority image data is performed. In step S3, it is determined whether there is a write request for non-priority image data. If there is a write request, the process proceeds to step S4, and if there is no write request, the process ends. In step S4, when the waiting time of the priority image data has elapsed, the process proceeds to step S5.

In step S5, writing control of non-priority image data is performed. In this way, the image data write request is monitored periodically, and if there is a priority image write request, the priority image write control is performed. If there is no request for writing a priority image and there is a request for writing a non-priority image, writing control of a non-priority image is performed when the request for writing a priority image has not been received for a predetermined time.

As shown in FIGS. 4 and 7D, the control means for controlling the printing procedure of the image forming apparatus according to the first embodiment of the present invention performs the second printing in both-side printing of the priority image. The procedure is automatically switched when the priority image is selected so that the first printing procedure is performed only when the non-priority image is printed on both sides.

As shown in FIG. 4, first, in step S1, it is determined whether or not the priority image data is double-sided printing. If the priority image data is double-sided printing, the process proceeds to step S2.
If priority image data is not double-sided printing, step S3
Proceed to. Next, in step S2, a first double-sided printing procedure is selected.

In step S3, it is determined whether or not the non-priority image data is double-sided printing. If the non-priority image data is double-sided printing, the process proceeds to step S4. If the non-priority image data is not double-sided printing, the process ends. In step S4, a second double-sided printing procedure is selected.

With such control, as shown in FIG. 7D, in the third printing procedure, the first recording sheet
Surface (C1), the first surface (C3) of the second recording sheet, 1
Second surface (C2) of the third recording sheet, first surface (C5) of the third recording sheet, first priority image (P1), second priority image (P2), third priority image (P3), the fourth priority image (P4), the second surface of the second recording sheet (C
4) First surface of the fourth recording sheet (C7), second surface of the third recording sheet (C6), first surface of the fifth recording sheet (C9), fourth recording The second side of the sheet (C8),
The first surface (C11) of the sixth recording sheet, the second surface (C10) of the fifth recording sheet, the second surface of the sixth recording sheet
Printing is performed in the order of the surface (C12).

In this embodiment, even in an image forming apparatus which takes a printing procedure so that the number of recording sheets in the printing unit and the re-feeding unit at the time of double-sided printing is larger than the number of standby positions, priority image selection for an input image is not performed. It is possible and user operability is improved.

The control means for controlling the printing procedure of the image forming apparatus according to the second aspect of the present invention, as shown in FIG. 5 and FIG. The priority image is not interrupted. The method can be changed according to the usage pattern of the user.

As shown in FIG. 5, first, in step S1, it is determined whether or not there is a request for writing priority image data. If there is, the process proceeds to step S2, and if not, the process proceeds to step S4. Next, in step S2, it is determined whether the non-priority image data is being printed on both sides. If the non-priority image data is being printed on both sides, the process proceeds to step S4. Step S3
Proceed to. In step S3, writing control of the priority image data is performed.

In step S4, it is determined whether there is a write request for non-priority image data. If there is a write request for non-priority image data, the flow advances to step S5. Ends. In step S5, after the waiting time of the priority image data has elapsed, the process proceeds to step S6.

In step S6, writing control of non-priority image data is performed. By such control, as shown in FIG. 7E, in the fourth printing procedure, the first surface (C1) of the first recording sheet and the first surface (C1) of the second recording sheet
3) The first surface (C5) of the third recording sheet, the second surface (C2) of the first recording sheet, the first surface (C7) of the fourth recording sheet, the second recording The second side of the sheet (C4),
The first surface of the fifth recording sheet (C9), the second surface of the third recording sheet (C6), the first surface of the sixth recording sheet (C11), the fourth surface of the recording sheet 2 (C8), 5
Second surface (C10) of the sixth recording sheet, second surface (C12) of the sixth recording sheet, first priority image (P1), second priority image (P2), third priority image (P3), 4th
Are printed in the order of the priority image (P4).

In the control means according to the embodiment of the present invention, the priority image can always be printed with the highest priority, but the non-priority image can be printed with low productivity even when there is no interruption of the priority image. Therefore, the control means of claim 2 can always perform double-sided printing with high productivity.
The priority image may be postponed.

For the user, for example, the control means of claim 1 is effective when using almost priority images, and the control means of claim 2 is effective when the frequency of use of non-priority images is high, but when the number of output sheets per time is small. It is.

Therefore, the control means for controlling the printing procedure of the image forming apparatus according to the third aspect of the present invention comprises the control means according to the first aspect and the second aspect.
The control means of the embodiment according to the present invention can be changed. As this changing means, for example, an operation unit (not shown) for selecting a copy mode (size and number of sheets) can be used.

The control means for controlling the printing procedure of the image forming apparatus according to the fourth aspect of the present invention, as shown in FIG. 6 and FIG. Even after the priority image is interrupted, the interruption is allowed only on the second side of the non-priority image.

As shown in FIG. 6, first, in step S1, it is determined whether or not there is a write request for priority image data. If there is a write request, the process proceeds to step S2. Proceed to S4. In step S2, it is determined whether the non-priority image data is being printed on both sides. If the printing is on both sides, the process proceeds to step S7. If not, the process proceeds to step S3.

In step S3, writing control of the priority image data is performed. In step S4, it is determined whether or not there is a write request for the non-priority image data. If there is a write request, the process proceeds to step S5; otherwise, the process ends.

In step S5, when the priority image waiting time has elapsed, the process proceeds to step S6. In step S6, writing control of the non-priority image data is performed. In step S7,
It is determined whether there is a write request for the second side of the non-priority image data. If there is a write request, the process proceeds to step S8. If there is no write request, the process proceeds to step S3 to perform the above-described processing. In step S8, writing control of the non-priority image data is performed.

With this control, as shown in FIG. 7F, in the fifth printing procedure, the first recording sheet
Surface (C1), the first surface (C3) of the second recording sheet, 3
First surface (C5) of the first recording sheet, second surface (C2) of the first recording sheet, first surface (C5) of the fourth recording sheet
7), the first priority image (P1), the second surface (C4) of the second recording sheet, the second priority image (P2), the second surface (C6) of the third recording sheet, 3 priority image (P3),
Second surface (C8) of the fourth recording sheet, fourth priority image (P4), first surface (C9) of the fifth recording sheet, first surface (C11) of the sixth recording sheet The printing is performed in the order of the second surface (C10) of the fifth recording sheet and the second surface (C12) of the sixth recording sheet. Note that the present invention is not limited to the above embodiment. That is, various modifications can be made without departing from the gist of the present invention.

[0050]

As described above, according to the image forming apparatus of the present invention, there is provided a writing unit for writing an electrostatic latent image on a photosensitive member based on image data, and one of a plurality of read image data. A selector for selectively reading one and outputting it to a writing unit; a printing unit for developing the electrostatic latent image and transferring it to a recording sheet before printing; and a paper feed for conveying the recording sheet before printing to the printing unit , A re-feeding unit for reversing the recording sheet with one side printed when double-sided printing is specified and transporting it to the printing unit again, and the recording sheet with one side printed when double-sided printing specified And a first printing procedure for preventing the number of recording sheets in the printing unit and the re-feeding unit from exceeding the number of waiting positions for re-feeding when the duplex printing is designated. The number of recording sheets in the printing section and A printing procedure switching means for selecting a second print procedure set to be greater than the number of paper standby position, when a plurality of image data at the same time is loaded,
Means for selecting priority image data which allows selection of priority image data, and control for selecting the first printing procedure for duplex printing of priority image data and selecting the second printing procedure for duplex printing of non-priority image data. Control means, so that even in an image forming apparatus which takes a printing procedure to make the number of recording sheets in the printing unit and the re-feeding unit larger than the number of standby positions during double-sided printing, it is possible to select a priority image for an input image. Is possible, and user operability is improved. In particular, since the priority image can be printed with the highest priority, it is suitable when the priority image is frequently printed.

Further, according to the image forming apparatus of the present invention, a writing unit for writing an electrostatic latent image on a photosensitive member based on image data, and selectively reading one of a plurality of read image data. A printing unit for developing the electrostatic latent image and transferring it to a recording sheet before printing; a paper feeding unit for transporting the recording sheet before printing to the printing unit; In the case where the recording sheet on which one side is printed is reversed and the sheet is reversed and then conveyed to the printing section again, and in the case of double-sided printing designation, the recording sheet on which one side is printed waits for re-feeding The first printing procedure and the inside of the printing unit and the re-feeding unit so that the number of recording sheets in the printing unit and the re-feeding unit does not exceed the number of waiting positions in the re-feeding unit and the printing unit and the re-feeding unit when duplex printing is specified. The number of recording sheets is less than the number of refeed standby positions. A printing procedure switching means for selecting a second printing procedure to increase the number of printing data, a selecting means for selecting priority image data which can select a priority image data when a plurality of image data are read at the same time; Non-priority image data is double-sided printed in the second printing procedure, and control means is provided for controlling interruption of priority image data during double-sided printing. Even in an image forming apparatus that takes a printing procedure in which the number of recording sheets is greater than the number of standby positions, priority image selection for an input image can be performed, and user operability is improved. In particular, it is suitable for the case where both-side printing with high productivity can be performed and the non-priority image is frequently used, but the number of output sheets at one time is small.

According to a third aspect of the present invention, there is provided an image forming apparatus for writing an electrostatic latent image on a photosensitive member based on image data, and selectively reading one of a plurality of read image data. A printing unit for developing the electrostatic latent image and transferring it to a recording sheet before printing; a paper feeding unit for transporting the recording sheet before printing to the printing unit; In the case where the recording sheet on which one side is printed is reversed and the sheet is reversed and then conveyed to the printing section again, and in the case of double-sided printing designation, the recording sheet on which one side is printed waits for re-feeding The first printing procedure and the inside of the printing unit and the re-feeding unit so that the number of recording sheets in the printing unit and the re-feeding unit does not exceed the number of waiting positions in the re-feeding unit and the printing unit and the re-feeding unit when duplex printing is specified. The number of recording sheets is less than the number of refeed standby positions. A printing procedure switching means for selecting a second printing procedure for increasing the number of image data, a priority image data selecting means for selecting priority image data when a plurality of image data are read at the same time; Control means for controlling to select the first printing procedure for duplex printing of image data and to select the second printing procedure for duplex printing of non-priority image data;
It is possible to switch between control means for performing double-sided printing in the printing procedure and controlling interruption of priority image data during double-sided printing, so that the number of recording sheets in the printing section and re-feeding section waits for double-sided printing. Even in an image forming apparatus that takes a printing procedure to increase the number of positions, it is possible to select a priority image for an input image, thereby improving the operability of the user. In particular, high productivity double-sided printing can be performed, and when priority images are frequently printed, priority images can be printed with top priority, and non-priority images can be used frequently but the number of prints per output is small. Also suitable for.

According to the image forming apparatus of the present invention, a writing unit for writing an electrostatic latent image on a photosensitive member based on image data and one of a plurality of read image data are selectively read. A printing unit for developing the electrostatic latent image and transferring it to a recording sheet before printing; a paper feeding unit for transporting the recording sheet before printing to the printing unit; In the case where the recording sheet on which one side is printed is reversed and the sheet is reversed and then conveyed to the printing section again, and in the case of double-sided printing designation, the recording sheet on which one side is printed waits for re-feeding The first printing procedure and the inside of the printing unit and the re-feeding unit so that the number of recording sheets in the printing unit and the re-feeding unit does not exceed the number of waiting positions in the re-feeding unit and the printing unit and the re-feeding unit when duplex printing is specified. The number of recording sheets is less than the number of refeed standby positions. A printing procedure switching means for selecting a second printing procedure for increasing the number of image data, a means for selecting priority image data which can select priority image data when a plurality of image data are read at the same time; Since there is provided control means for performing double-sided printing of the priority image data in the second printing procedure and permitting printing of the non-priority image data only on the second side even after the priority image data is interrupted,
Even in an image forming apparatus that performs a printing procedure in which the number of recording sheets in the printing unit and the re-feeding unit during duplex printing is larger than the number of standby positions, it is possible to select a priority image for an input image, thereby improving user operability. Is improved. In particular, even after the priority image is interrupted during double-sided printing of the non-priority image, interruption can be permitted only on the second side of the non-priority image.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a digital copying machine as an example of an image forming apparatus to which the present invention is applied.

FIG. 2 is a block diagram for selecting image data from a plurality of image input means and outputting it to a writing unit.

FIG. 3 is a flowchart illustrating control of a priority image.

FIG. 4 is a flowchart illustrating control of a printing procedure of the image forming apparatus according to the embodiment of the present invention;

FIG. 5 is a flowchart illustrating control of a printing procedure of the image forming apparatus according to the embodiment of the present invention;

FIG. 6 is a flowchart illustrating control of a printing procedure of the image forming apparatus according to the embodiment of the present invention;

7A and 7B are diagrams for explaining a printing procedure, wherein FIG. 7A shows a first printing procedure, FIG. 7B shows a second printing procedure,
(C) shows a conventional printing procedure, (d) shows a third printing procedure, (e) shows a fourth printing procedure, and (f) shows a fifth printing procedure.

[Explanation of symbols]

 5 Reading Unit 20 Writing Unit 24 Photoconductor 26 Printing Unit 28 Paper Feeding Unit (Paper Feeding Unit) 34 Refeeding Unit (Refeeding Unit) 37 First Standby Position (Refeeding Standby Position) 38 Second Standby Position ( Re-feeding standby position) 40 control device (control means) 41 selector S recording sheet

Claims (4)

[Claims] A writing unit that writes an electrostatic latent image on a photoconductor based on image data; a selector that selectively reads one of a plurality of read image data and outputs the data to a writing unit; A printing unit that develops the electrostatic latent image and transfers it to the recording sheet before printing, a paper feeding unit that conveys the recording sheet before printing to the printing unit, and one side that has been printed when double-sided printing is specified A re-feeding unit for reversing the recording sheet and transporting it to the printing unit again; a re-feeding standby position for waiting for re-feeding of the recording sheet that has been printed on one side when duplex printing is specified; First, the number of recording sheets in the printing unit and the re-feed unit does not exceed the number of re-feed standby positions when designated.
A printing procedure switching means for selecting a printing procedure and a second printing procedure for making the number of recording sheets in the printing section and the re-feed section larger than the number of re-feed standby positions; A means for selecting priority image data which can select priority image data when data is read; a first printing procedure for duplex printing of priority image data; a second printing procedure for duplex printing of non-priority image data; An image forming apparatus comprising: a control unit configured to perform control so as to select a procedure. 2. A writing unit for writing an electrostatic latent image on a photoconductor based on image data, a selector for selectively reading one of a plurality of read image data and outputting the data to a writing unit, A printing unit that develops the electrostatic latent image and transfers it to the recording sheet before printing, a paper feeding unit that conveys the recording sheet before printing to the printing unit, and one side that has been printed when double-sided printing is specified A re-feeding unit for reversing the recording sheet and transporting it to the printing unit again; a re-feeding standby position for waiting for re-feeding of the recording sheet that has been printed on one side when duplex printing is specified; First, the number of recording sheets in the printing unit and the re-feed unit does not exceed the number of re-feed standby positions when designated.
A printing procedure switching means for selecting a printing procedure and a second printing procedure for making the number of recording sheets in the printing section and the re-feed section larger than the number of re-feed standby positions; Means for selecting priority image data which can select priority image data when data is read; and printing the non-priority image data on both sides in the second printing procedure, and prohibiting interruption of the priority image data when printing on both sides. An image forming apparatus comprising: 3. A writing unit for writing an electrostatic latent image on a photoconductor based on image data, a selector for selectively reading one of a plurality of read image data and outputting the data to a writing unit, A printing unit that develops the electrostatic latent image and transfers it to the recording sheet before printing, a paper feeding unit that conveys the recording sheet before printing to the printing unit, and one side that has been printed when double-sided printing is specified A re-feeding unit for reversing the recording sheet and transporting it to the printing unit again; a re-feeding standby position for waiting for re-feeding of the recording sheet that has been printed on one side when duplex printing is specified; First, the number of recording sheets in the printing unit and the re-feed unit does not exceed the number of re-feed standby positions when designated.
A printing procedure switching means for selecting a printing procedure and a second printing procedure for making the number of recording sheets in the printing section and the re-feed section larger than the number of re-feed standby positions; A means for selecting priority image data which can select priority image data when data is read; a first printing procedure for duplex printing of priority image data; a second printing procedure for duplex printing of non-priority image data; Control means for controlling so as to select a procedure, and control means for controlling non-priority image data to perform double-sided printing in the second printing procedure and to inhibit interruption of priority image data during double-sided printing. An image forming apparatus comprising: 4. A writing unit for writing an electrostatic latent image on a photoconductor based on image data, a selector for selectively reading one of a plurality of read image data and outputting the data to a writing unit, A printing unit that develops the electrostatic latent image and transfers it to the recording sheet before printing, a paper feeding unit that conveys the recording sheet before printing to the printing unit, and one side that has been printed when double-sided printing is specified A re-feeding unit for reversing the recording sheet and transporting it to the printing unit again; a re-feeding standby position for waiting for re-feeding of the recording sheet that has been printed on one side when duplex printing is specified; First, the number of recording sheets in the printing unit and the re-feed unit does not exceed the number of re-feed standby positions when designated.
A printing procedure switching means for selecting a printing procedure and a second printing procedure for making the number of recording sheets in the printing section and the re-feed section larger than the number of re-feed standby positions; Means for selecting priority image data which can select priority image data when the data is read; non-priority image data is printed on both sides by the above-mentioned second printing procedure; A control unit for performing control so as to permit printing of non-priority image data.