JP2002049202A - Image-forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance productivity higher be efficiently forming an image, even if the image of a document whose image size is equal to or larger than the reference image size. SOLUTION: When the start of copying the image of a full color document is designated in an automatic color selection mode in a digital color copying machine 1, an image memory is prepared with five planes in monochrome conversion, when the size of the document placed on an automatic document feeder is A3 size larger than the reference image size. As for the timing of reading operation for (N+1)-th document, document reading operation is started, by starting forming the image of cyan (C) which is the 3rd image forming color of N-th document, and image-forming processing for the image of yellow (Y) of the (N+1)-th document is started, immediately after finishing forming the image of the N-th document.

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 capable of simultaneously forming an image on a plurality of surfaces with a digital color copier, a printer, or the like, and more particularly to an improvement in productivity of full-color image formation. It is.

[0002]

2. Description of the Related Art For example, when a plurality of originals are simultaneously copied by a digital color copying machine, a standard is set as disclosed in Japanese Patent Application Laid-Open No. Hei 10-221900 to improve the productivity of image formation. An image reading apparatus capable of simultaneously reading an image of two pages of an image size, for example, A4 size, and a length of at least twice the size of A4 size, that is, A3
An intermediate transfer belt having a length to hold an image of a size, simultaneously reading two A4 size originals on two sides, and simultaneously transferring a toner image formed on a photoreceptor by an image signal of the read original onto the intermediate transfer belt. The toner image transferred on the surface and then transferred to the intermediate transfer belt is secondarily transferred to a continuously fed transfer sheet.

[0003]

As described above, in a digital color copying machine in which two A4-size original images are simultaneously formed on two sides, a plurality of A4-size originals must be copied. , Can improve the productivity of image formation,
In recent years, when using a sheet-through type automatic document feeder that can sequentially detect the size of a document placed on a document table adopted in a copying machine, and when copying a plurality of documents of A4 size or more, the productivity is increased. No improvement could be made.

In order to prevent the production of the automatic color mode from decreasing, black (Bk) has been used as the first color of an image. However, the order of the image formation color greatly affects an output image. Making the black (Bk) image the final color can increase the image forming efficiency.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus which can improve the above point, efficiently form an image of a document having a size larger than a reference image size, and can further improve productivity. is there.

[0006]

According to the present invention, there is provided an image forming apparatus comprising: a sheet-through type automatic document feeder capable of sequentially detecting the size of a document placed on a document table; reading an image of a document in a full color mode; An image reading apparatus having a color determination function of determining whether or not the read original is a color original; and an image signal of the read image is converted into yellow (Y), magenta (M), cyan (C), and black (K) colors. An image memory for storing a visible image of any of yellow (Y), magenta (M), cyan (C), and black (K) on the photosensitive member based on the read image signal; An image holding means capable of simultaneously holding two toner images of a reference image size formed on the photosensitive member for two surfaces, wherein the visible images transferred to the image holding means are sequentially fed. If the size of the original placed on the automatic document feeder is larger than the reference image size when the copy start is instructed in the automatic color selection mode, the image memory Five planes are prepared in conversion, and the timing of the reading operation of the (N + 1) -th document is started in the full color mode by starting the formation of the third color of the N-th document. It is characterized by the following.

A second image forming apparatus according to the present invention includes a sheet-through type automatic document feeder capable of sequentially detecting the size of a document placed on a document table, a document which reads a document image in a full-color mode, and a read document. An image reading apparatus having a color determination function of determining whether or not a document is a color document, and storing image signals of the read image for each color of yellow (Y), magenta (M), cyan (C), and black (K) An image forming unit for forming a visible image of any one of yellow (Y), magenta (M), cyan (C), and black (K) on a photosensitive member according to a read image signal; Image holding means capable of simultaneously holding two toner images of a reference image size formed on the image holding means, and transferring the visible images transferred to the image holding means to transfer paper fed sequentially. In the image forming apparatus, when a copy start is instructed in the automatic color selection mode, if the size of a document placed on the automatic document feeder is equal to or smaller than a reference image size, the image memory is converted to a single color by 10 The plane is prepared, and the timing of the reading operation of the odd-numbered (2N + 1) th page of the original is started in the full color mode by starting the image formation of the first color of the 2Nth original, The timing of the reading operation of the document of the even-numbered (2N + 2) pages is such that in the case of the full color mode, the document reading operation is started by forming the third color of the 2N-th document. .

A third image forming apparatus according to the present invention includes a sheet-through type automatic document feeder capable of sequentially detecting the size of a document placed on a document table, a document read in full color mode, and a document read. An image reading apparatus having a color determination function of determining whether or not a document is a color document, and storing image signals of the read image for each color of yellow (Y), magenta (M), cyan (C), and black (K) An image forming unit for forming a visible image of any one of yellow (Y), magenta (M), cyan (C), and black (K) on a photosensitive member according to a read image signal; Image holding means capable of simultaneously holding two toner images of a reference image size formed on the image holding means, and transferring the visible images transferred to the image holding means to transfer paper fed sequentially. In the image forming apparatus, when the copy start is instructed in the automatic color selection mode, if the size of the document placed on the automatic document feeder is equal to or smaller than the reference image size, the image memory is converted to a single color by 8 The plane is prepared, and the timing of the reading operation of the document of the odd (2N + 1) th page is started in the case of the full color mode by starting the image formation of the second color of the 2Nth document, The timing of the reading operation of the document of the even-numbered (2N + 2) pages is characterized in that in the full color mode, the document reading operation is started by starting to form the final color of the 2N-th document.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A digital color copying machine according to the present invention has a printer engine and a sheet-through type double-sided automatic document feeder (hereinafter referred to as "SRADF"). The printer engine has an image reading unit, an image forming unit, a primary transfer unit, a secondary transfer unit, a paper feed unit, and a fixing unit. The image reading unit reads an image of a document sent by SRADF. The image forming unit includes a charging charger, an image writing unit, and yellow (Y), magenta (M), cyan (C),
Color developing unit and drum clear made of black (K)
An electrostatic latent image is formed on the photosensitive member by a laser beam from the image writing unit, and the formed electrostatic latent image is visualized by a color developing unit to form a toner image. The primary transfer unit has an intermediate transfer belt, a primary transfer unit, a reference position sensor, and a cleaning unit, and primarily transfers a toner image formed on a photoconductor to the intermediate transfer belt. The intermediate transfer belt is
It has a reference image size, for example, twice as long as the A4 size, that is, a length for holding an A3 size image, and can simultaneously transfer toner images for two sides of the A4 size or less. Reference marks are provided at regular intervals in the non-image portion. The intermediate transfer belt is separated from the surface of the photoconductor by a contact / separation mechanism except when the toner image on the photoconductor is primarily transferred, and is pressed against the surface of the photoconductor only when the toner image is primarily transferred. The secondary transfer unit secondary-transfers the toner image transferred to the intermediate transfer belt onto transfer paper sent from a paper supply unit. The fixing unit fixes the toner image transferred to the transfer paper. The SRADF sequentially detects and sends out the size of the original placed on the original table.

In this digital color copying machine, when an instruction to start copying a full-color original image is given in the automatic color selection mode, the size of the original placed on the automatic original feeder is smaller than the reference image size. In the case of a large A3 size, five planes of image memory are prepared in monochromatic conversion, and (N +
1) The timing of the reading operation of the N-th original is such that the reading operation of the N-th original is started by starting the image formation of cyan (C), which is the third color of the N-th original. Immediately after the completion of image formation, image formation processing for the yellow (Y) image of the (N + 1) th document is started, and copying of a document larger than the reference size A4, such as A3, is quickly performed. .

[0011]

FIG. 1 is a block diagram of one embodiment of the present invention.
As shown in the figure, the digital color copying machine 1 has a printer engine 2 and a sheet-through type duplex automatic document feeder (hereinafter, referred to as SRADF) 3. The printer engine 2 includes an image reading unit 4, an image forming unit 5, a primary transfer unit 6, a secondary transfer unit 7, a paper feed unit 8, and a fixing unit 9. Image reading unit 4 is SR
The original image sent by the ADF 3 is read. The image forming unit 5 includes a charging charger 52 disposed around a photoreceptor 51, an image writing unit 53, and a rotary type color developing device including yellow (Y), magenta (M), cyan (C), and black (K). A latent image formed on the photoreceptor 51 by a laser beam from the image writing unit 53, and the formed electrostatic latent image is formed by the color developing unit 54. Visualize to form a toner image. The density sensor 55 is a photosensitive member 51 on which a toner image is formed.
The density of the specific pattern drawn in is detected to confirm whether a toner image is formed at an appropriate density. The primary transfer unit 6 includes an intermediate transfer belt 61 and a primary transfer unit 62
And a plurality of tension rollers 63, a secondary transfer roller 64, a reference position sensor 65, and a cleaning unit 66, and primarily transfer the toner image formed on the photoconductor 51 to the intermediate transfer belt 61. The intermediate transfer belt 61 has a reference image size, for example, a length that is at least twice as large as an A4 size, that is, a length that holds an A3 size image, and simultaneously transfers toner images for two sides of an A4 size or less. The reference marks 67 are provided at regular intervals in the non-image portion. The intermediate transfer belt 61 is separated from the surface of the photoreceptor 51 by a contact / separation mechanism (not shown) except when the toner image on the photoreceptor 51 is primarily transferred, and remains on the surface of the photoreceptor 51 only when the toner image is primarily transferred. It is pressed. The secondary transfer unit 7 secondary-transfers the toner image transferred to the intermediate transfer belt 61 onto transfer paper sent from the paper supply unit 8. The fixing unit 9 fixes the toner image transferred to the transfer paper.

The SRADF 3 has a document feed tray 101 and a document discharge tray 102 arranged above and below the platen 10 in two stages, and a reversing tray 103 for providing a reversing path for reversing the document. And the document discharge tray 102. Document feed tray 10
A document feed path 104 from 1 to the image reading unit 4 includes a feed roller 105, a feed belt 107 wound around a feed clutch 106, a separation roller 108, and a pull-out roller 109. The discharge conveyance path 110 from the image reading unit 4 to the document discharge tray 102 and the reversing tray 103 has an auxiliary roller 111 and a paper discharge roller 112. On the downstream side of the discharge roller 112 of the discharge conveyance path 110, a reversing switching mechanism 1 that operates up and down by a solenoid to switch the conveyance path between the document discharge tray 102 and the reversing tray 103.
13. A re-feeding roller 115 is provided in a reversing document conveying path 114 for feeding a document from the reversing tray 103. The document feed tray 101 has a next document detection sensor 116 and a plurality of size detection sensors 117, and the registration sensor 11 is located downstream of the pull-out roller 109 in the document conveyance path 104.
And a discharge sensor 119 downstream of the auxiliary roller 112 in the discharge conveyance path 110. The reversing tray 103 has a reversing roller 120 and a reversing tray sensor 121.

Each roller provided on the SRADF 3 is driven by two stepping motors,
07, the separation roller 108, and the reversing roller 120 are driven by a reversing paper feed motor 122 that rotates forward and backward, and the pull-out roller 109, the auxiliary roller 111, and the paper discharging roller 112
It is driven by a transport motor 123 that rotates only in the direction. The reversing roller 120 is provided with a torque limiter to cope with a case where the document moves in the rotating direction.

The reverse feeding motor 122 and the transport motor 1
As shown in the block diagram of FIG. 2, the drive control unit 23 includes RAMs 124 and 125 and a DMA controller 12.
6, 127, a clock generator 128, an output compare register 129, a 16-bit counter 130, a comparator 131, and a timing pattern controller (hereinafter referred to as T
A PC 132, an I / O port 133, and drive circuits 134 and 135, and these operations are managed by the CPU. The RAM 124 has a constant speed for driving the motor at a target speed in order to stabilize the rotation of the stepping motor, a through-up in which the motor speed is gradually increased until the target speed is reached, and when stopping the motor. Slew-down cycle data for gradually lowering the motor speed is stored as a table. RA
An output pattern for driving the motor is stored in M125. The DMA controller 126 transfers the cycle data stored in the RAM 124 to the output compare register 129. DMA controller 127 is R
The output pattern stored in the AM 125 is
Transfer to 2. In both the DMA controllers 126 and 127, the transfer of the periodic data to the output compare register 129 is triggered by the DMA controller 126 to transfer the next data. Clock generator 12
8 generates a reference clock. This clock generator 12
As 8, a clock generator for generating an operation clock of the CPU may be used. Output compare register 1
29 stores the time (counter value) for outputting the output pattern to the motor next time. The 16-bit counter 130 receives the reference clock output from the clock generator 128 and counts up for each clock. Comparator 13
1 compares the counter value of the output compare register 129 with the counter value of the 16-bit counter 130, and generates a compare match signal when the counter values become equal. The TPC 132 has a next data register 136 and a port data register 137. When a compare match signal is input, the next data register 136 transfers the contents of the output pattern already stored in the next data register 136 to the port data register 137. And
Immediately thereafter, the next output pattern is stored by the DMA controller 127. The port data register 137 generates motor clock, rotation direction, phase excitation, and on / off signals according to the output pattern. In this way, the output pattern is directly written to the port data register 137,
The reason why it is not output to the I / O port 133 is that the motor clock, the rotation direction, the phase excitation, and the on / off signals are simultaneously output as compare match signals even when they are not assigned without a 1-byte register. This is to make it possible. The I / O port 133 is an output port that can be directly controlled by the CPU, and outputs a two-phase excitation or a one-two phase excitation phase excitation signal and an on / off signal to a drive circuit 134 that drives the transport motor 123. Drive circuit 13
5 receives the motor clock output from the port data register 137, the rotation direction, the phase excitation, and the ON / OFF signal, and drives the reverse sheet feeding motor 122. The reverse sheet feeding motor 122 and the transport motor 123 are driven at both rising and falling edges of the motor clock output from the port data register 137.

Next document detection sensor 116 and size detection sensor 1 provided on document feed tray 101 of SRADF3
Reference numeral 17 denotes a reflection type sensor, which is turned on in a state where the sensor is covered with a document. When performing a reading operation on a plurality of originals, the next original detection sensor 116 determines whether there is a next original in addition to the original to be read. The size detection sensor 117 determines the size of a document placed on the document feed tray 101. That is, when the original to be read is conveyed to the registration sensor 118, it is determined whether or not the next original exists while the next original detection sensor 116 is on / off. However, when the determination result of the size detection sensor 117 is a large size such as A3 size, even if the original is conveyed to the registration sensor 118, the original itself turns on the next original detection sensor 116. The determination of the presence or absence of the next original using the next original detection sensor 116 is limited to the A4 size. For a document exceeding the A4 size, the presence or absence of the document is determined using the next document detection sensor 116 with the end of reading as a trigger.

The operation when the document is transported to the registration sensor 118 by the SRADF 3 will be described. (1) Paper feed operation for reading the front side of a document The document set on the document feed tray 101 is picked up by a paper feed belt 107 and a separation roller 108.
The document is separated into one sheet and sent to the document conveying path 104. The sent document is conveyed by the pull-out roller 109, and stops after the registration sensor 118 detects the leading edge of the document. (2) Paper feed operation for reading the back side of the document The document set on the document feed tray 101 is picked up by the feed belt 107 and the separation roller 108,
The document is separated into one sheet and sent to the document conveying path 104. Thereafter, the document is conveyed by the pull-out roller 109 and the auxiliary roller 111, and after the paper discharge sensor 119 detects the leading edge of the document, the reversing switch 113 is turned on, the conveyance path is switched to the reversing tray 103, and the document is sent to the reversing tray 103. After the trailing end of the document is detected by the paper discharge sensor 119, the reversing roller 12
It is conveyed to the switchback point on the side of the inversion switching 113 of 0 and stops. Then, the reverse sheet feeding motor 12
2. Change the rotation direction and rotate in the opposite direction. In the meantime, the reversing switch 113 is turned off and the transport path is switched to the reverse original transport path 1.
14, the reversing roller 120 and the re-feed roller 11
5 and the document is inverted by the pull-out roller 109 and transported to the position of the registration sensor 118. (3) Reversal re-feeding operation of document at registration position A document stopped at the position of registration sensor 118 is conveyed in the direction of image reading unit 4, and after the leading edge of the document is detected by discharge sensor 119, reversal switching is performed. The feeding path is switched to the reversing tray 103 by turning on the jam 113 and the sheet is sent to the reversing tray 103. Then, after the paper discharge sensor 119 detects the rear end of the document, the document is conveyed to a switchback point on the reversing switch 113 side of the reversing roller 120 and stopped. After that, the rotation direction of the reversing sheet feeding motor 122 is changed and the sheet is rotated in the opposite direction. In the meantime, the reversing switch 113 is turned off and the conveyance path is switched to the reversal document conveyance path 114, and the reversing roller 1
The document is inverted by the sheet feed roller 20, the re-feed roller 115, and the pull-out roller 109, and transported to the position of the registration sensor 118. (4) Operation of transporting the read original again to the position of registration sensor 118 After the original stopped at the position of registration sensor 118 is transported in the direction of image reading unit 4 and exposed and read by image reading unit 4, When the paper discharge sensor 119 detects the leading edge of the document, the reversing switch 113 is turned on, the conveyance path is switched to the reversing tray 103, and the document is sent to the reversing tray 103. Then, after the paper discharge sensor 119 detects the rear end of the document, the document is conveyed to a switchback point on the reversing switch 113 side of the reversing roller 120 and stopped. afterwards,
The rotation direction of the reverse paper feed motor 122 is changed and the motor is rotated in the reverse direction. In the meantime, the reversing switch 113 is turned off and the conveyance path is switched to the reversal document conveyance path 114, and the reversing roller 120
Then, the original is reversed by the re-feed roller 115 and the pull-out roller 109 and transported to the position of the registration sensor 118. (5) Discharge Operation After Reading A document stopped at the position of the registration sensor 118 is conveyed in the direction of the image reading unit 4, exposed and read by the image reading unit 4, and then the reversing switch 113 is turned off. The document is then discharged to the document discharge tray 102 with the conveyance path set to the document discharge tray 102 side. (6) Additional operations In addition to the above basic operations, the following operations are required as additional operations required in actual operation. (A) Pushing operation When a document stops at the switchback point and is re-fed to the position of the registration sensor 118, the document is conveyed from the switchback point to the re-feed roller 115 in order to correct skew during conveyance of the document. Then, the reverse feeding motor 122 is turned off and only the conveyance motor 123 is turned on to hit the original against the re-feed roller 115, and the original is conveyed until the original is bent to correct the skew. (B) Next Document Feeding Operation When There is Next Document in Document Feeding Tray 101 When a document is conveyed from document feeding tray 101 and the next document is present in document feeding tray 101, the next document is Subsequently, the sheet is conveyed with the sheet supply clutch 106 of the sheet supply belt 107 turned on so that the sheet is conveyed to the position of the registration sensor 118. (C) Feeding operation of next document when document is present in reversing tray 103 When document is present in reversing tray 103, document feeding tray 1
When transporting the next original from 01, the reverse tray 103
The feeding clutch 1 of the feeding belt 107 prevents the originals from overlapping after turning the reversing tray sensor 121 off.
At step 06, the next original is conveyed to the position of the registration sensor 118. (D) Discharge Operation After Interruption of Operation The discharge operation after interruption of operation is performed by combining the above-described basic operations in order to adjust the page order, and is discharged face down to the document discharge tray 102.

As shown in the block diagram of FIG. 3, the control unit of the printer engine 2 includes a reading control unit 10, an image processing device (hereinafter, referred to as IPU) 11, a motherboard 12, and a controller 13. The reading control unit 10 controls a reading operation of the image reading unit 4 and sends a read image signal to the IPU 11. The IPU 11 performs various kinds of processing such as various kinds of filtering of the transmitted image signal. The controller 13 includes a program ROM 14, a system memory and an I / O
It has a memory 15 as an image memory for storing the image data processed by the PU 11 and transferring the stored image data to the printer engine 2, and an optional hard disk 16. Control behavior. The reading control unit 10 and the IPU 11
And the controller 13 and the printer engine 2 are connected by an image bus which can also perform command communication.

The image reading unit 4 simultaneously reads the yellow (Y), magenta (M), cyan (C), and black (K) images as shown in the explanatory diagram of FIG. 13 is transferred to the memory 15, and one line data of yellow (Y), magenta (M), cyan (C), and black (K) is read line by line (line sequential) for each read line. Memory spaces 15Y, 15M,
15C and 15K.

In this embodiment, the resolution of a copy read image is described as 1 pixel = 600 dpi / 2 binary data gradation, but this quantization is not particularly limited. For example, 1 pixel = 600 dpi / 8 bit gradation. In that case, it simply becomes 8 times. When an image of a document is read at this resolution, the capacity of the image memory required for each color of A3 size (420 mm × 297 mm) is {(420 × 600) /25.4} × {(297 × 600) /25.4} = 69605059 (dot), and since 1 byte = 8 dots (bit) as image data, 69605059/8 = 8700632 (byte) = 8.7 (Mbyte). This is used as an image memory per plane.

Further, the linear speed of reading of the original by the image reading unit 4, that is,
Image transfer speed per line to the memory 15 and the linear speed of writing by the image writing unit 53, that is, the controller 13
The image transfer speed per line from the printer to the printer engine 2 is the same. That is, when the reading of the document is started and the read image is input to the memory 15 of the controller 13, the read image data can be transferred to the printer engine 2. Also,
The image forming order in the printer engine 2 is yellow (Y),
The processing is performed in the order of magenta (M), cyan (C), and black (K).

The operation for copying an A3 size document larger than the A4 size, which is the reference size, in which two images cannot be simultaneously formed by the digital copying machine 1 is described below. A description will be given with reference to a time chart showing the reading and image formation of an original in the color mode and the state of the image memory.

When the copying operation of the A3 size original is executed by automatic color selection, an image memory for 5 planes of the maximum copying size is mounted so as not to lower the copying productivity. That is, since copying up to A3 size is possible, an image memory of 8.7 (Mbyte) × 5 = 43.5 (Mbyte) is employed.

As shown in FIG. 5, after the time necessary to read an A3-size original having a length of 420 mm has elapsed (501), when all the originals have been read, the color judgment of the read image is performed. Is performed (502). Yellow Y1, magenta M1,
Image data of each component of cyan C1 and black K1 is stored in the space of plane 1, plane 2, plane 3, and plane 4 of the image memory secured in the memory 15 of the controller 13 (510 to 513). in this case,
Since the document to be read is A3 size, the intermediate transfer belt 6
Only one image can be transferred to one. Therefore, when forming a full-color image, the printer engine 2
Represents the intermediate transfer belt 61 as shown in the image forming timing.
4 times, yellow Y1, magenta M1, cyan C
1, full-color image formation is performed by repeatedly forming an image of black K1.

During the full-color image formation, since the linear speed for reading the original and the linear speed for writing by the image writing unit 53 are simultaneous, reading of the second original is
The reading is started when the memory of four planes from plane 1 to plane 4 is available. That is, as shown in FIG.
The reading of the second document is started, triggered by the start of image formation of cyan C1 of the first document (503). The read image data of yellow Y2, magenta M2, and cyan C2 of the second document are stored in plane 1, plane 2, and plane 3 of the image memory, respectively. However, when the reading of the second document is started, the image formation of the black K1 image of the first document has not yet started.
The black K2 image read from the second document cannot be transferred to the plane 4, which is the memory space storing the black K1 image data of the first document. Therefore, the image data of black K2 of the second document is stored in plane 5 of the image memory.

Since the reading time of the second document has been completed earlier than when the image forming operation of the first document on black K1 is completed, the image forming operation of black K1 on the first document has been completed. Is completed, the color determination of the second document has been performed, so immediately after the completion of the black K1 image formation of the first document, the image forming process of the yellow Y2 image of the second document is performed. Put in. That is, the timing of the reading operation of the (N + 1) -th document is such that the document reading operation is started by starting the formation of the cyan C image which is the third color in the full color mode, and the image reading unit 4 The read image data is transferred from the read control unit 10 to the controller 13.
, And the images of yellow Y, magenta M, and cyan C are stored in planes 1 and 2 of a predetermined color component in the image memory.
2, and the black K image is stored in an empty area of either plane 4 or plane 5.

In this manner, the black K of the Nth original is
Immediately after the end of the image formation, the image forming process for the yellow (Y) image of the (N + 1) th document can be started, and the copying operation of the document larger than the reference size A4, such as A3, can be performed quickly. This can improve productivity when copying a large-sized document.
Here, the number of planes in the image memory is set to five. For example, when the number of planes is set to four, as shown in FIG. Since the color determination of the image cannot be performed, the intermediate transfer belt 61 skips one round in the image forming process, so that the image forming process of the image of the second document is delayed by that time, and the productivity is reduced. This is for avoiding a drop.

Next, an operation of copying an image of a document of A4 size which is a reference size, for example, will be described with reference to a time chart of FIG.

The image of the A4 size document is simultaneously transferred to the intermediate transfer belt 61 for two surfaces, and the toner images for the two surfaces transferred to the intermediate transfer belt 61 are secondarily transferred to a continuously fed transfer paper. be able to. Since the storage capacity of one plane of A3 size is 8.7 (Mbyte), the storage capacity of one plane of A4 size is 8.7 / 2 = 4.35 (Mbyt
e). Therefore, 4.35 × 10 = 43.
A storage capacity of 5 (Mbyte) is sufficient.

As shown in FIG. 7, when the time required to read an A4 size original having a length of 210 mm has elapsed and all the first original has been read, the color judgment of the read image is performed. Is performed. The image data of the yellow, magenta M1, cyan C1, and black K1 components of the first document read out are stored in the planes 1, 2, 3, and 3 of the image memory secured in the memory 15 of the controller 13. 4 space. Subsequently, the second document is read, the color of the read image is determined, and then the read yellow Y2, magenta M2, cyan C2, and black K are read.
The image data of each component 2 is stored in the space of the plane 5, plane 6, plane 7, and plane 8 of the image memory secured in the memory 15. In this case, since the original to be read is A4 size, two images can be transferred to the intermediate transfer belt 61 at the same time in the image forming process, and the maximum productivity can be obtained when the two images are trimmed. Therefore, when performing full-color printing, as shown in the timing of the image forming process in FIG.
Magenta M1, Magenta M2, Cyan C1, Cyan C
2, an image forming operation is performed in the order of black K1 and black K2, and two full-color images of the original are continuously formed on the transfer paper.

During the full-color image formation, the planes 9 and 10 of the image memory are not used, and the linear speed for reading the original and the linear speed for writing in the image writing unit 53 are the same. The reading of the third document is triggered by the start of yellow Y2 image formation of the second document as a trigger so that the images of each color of the third document can be stored in the image memory. . Then, the yellow Y3 and magenta M3 of the read image are stored in unused planes 9 and 10, and the image of cyan C3 is stored in yellow Y3 and magenta M3.
Is stored in the plane 1 in which the image formation is completed, and the image of black K3 is stored in the plane 5 in which the image data of the yellow Y2 in which the image formation is started is stored. Next, the reading of the fourth document is started with the start of image formation of cyan C2 of the image of the second document as a trigger). At this time, the components of yellow Y4, magenta M4, cyan C4, and black K4 of the image read from the fourth document are the magenta M1 for which the image forming operation has been completed.
And plane 2 in which image data of cyan C1 is stored
And plane 3 and the image data of magenta M2 and cyan C2 for which the image forming operation has been completed are stored in the planes 6 and 7, respectively.

That is, for the original of the odd (2N + 1) th page, in the full color mode, the original reading operation is started simultaneously with the start of the image formation of the 2N-th yellow Y, which is the first image forming color, and is read. The image data of each color is transferred to a free plane area of the image memory and stored.
In the case of the full-color mode, the document reading operation of the even-numbered (2N + 2) -page document is started simultaneously with the start of forming the 2N-th sheet of cyan C, which is the third image forming color, and The image data is transferred and stored in a free plane area of the image memory. In this manner, images of a plurality of originals can be formed continuously, and the productivity of copying can be increased.

Although the above embodiment has been described with reference to the case where a 10-plane image memory is provided in the memory 15 of the controller 13 when copying an A4 size document, the image memory may be composed of 8 planes. In this case, the image memory only needs to have a storage capacity of 4.35 (Mbyte) × 8 = 34.8 (Mbyte). The operation when this image memory is composed of eight planes will be described with reference to the time chart of FIG.

As shown in FIG. 8, when the time required to read an A4-size original having a length of 210 mm has elapsed and all the first original has been read, the color judgment of the read image is performed. Is performed. The image data of the yellow, magenta M1, cyan C1, and black K1 components of the first document read out are stored in the planes 1, 2, 3, and 3 of the image memory secured in the memory 15 of the controller 13. 4 space. Subsequently, the second document is read, the color of the read image is determined, and then the read yellow Y2, magenta M2, cyan C2, and black K are read.
The image data of each component 2 is stored in the space of the plane 5, plane 6, plane 7, and plane 8 of the image memory secured in the memory 15. In this case, since the original to be read is A4 size, two images can be transferred to the intermediate transfer belt 61 at the same time in the image forming process, and the maximum productivity can be obtained when the two images are trimmed. Therefore, when performing full-color printing, as shown in the timing of the image forming process in FIG.
Magenta M1, Magenta M2, Cyan C1, Cyan C
2, an image forming operation is performed in the order of black K1 and black K2, and two full-color images of the original are continuously formed on the transfer paper.

When the full-color image is formed, since the linear speed for reading the original and the linear speed for writing by the image writing section 53 are simultaneous, reading of the third original is
Reading is started with the start of magenta M2 image formation of the second document as a trigger so that the image of each color of the third document can be stored in the image memory. At this time, the yellow Y3, magenta M3, and cyan C3 components of the image read from the third document are stored in planes 1, 2, and 5 of yellow Y1, magenta M1, and yellow Y2 for which image formation has been completed. The component of the black K3 is stored in the plane 6 in which the image data of the magenta M2 which has started the image formation is stored. Next, the reading of the fourth document is started with the start of image formation of black K2 of the second document as a trigger. Then, the components of yellow Y4, magenta M4, and cyan C4 of the image read from the fourth document are stored in planes 3, 4, and 7 in which cyan C1, black K, and cyan C2 are stored. And black K4
Is stored in the plane 8 in which the image data of the black K2 which has started the image formation is stored.

That is, for the document of the odd (2N + 1) th page, in the full-color mode, the document reading operation is started simultaneously with the start of forming the 2Nth magenta M image which is the second image forming color. Then, the read image data of each color is transferred to an empty plane area of the image memory and stored. In addition, in the case of the full-color mode, the original reading operation is started at the same time as the formation of the 2N-th black K image, which is the final image forming color, in the full-color mode, and the even-numbered (2N + 2) -page original is read. The image data of each color is transferred and stored in a free plane area of the image memory. In this manner, images of a plurality of documents can be continuously formed, so that copying productivity can be increased and the storage capacity of the image memory can be reduced.

[0036]

As described above, according to the present invention, when a full-color image is formed by combining an image forming apparatus such as a digital color copier or a printer with a sheet-through type automatic document feeder, Can be formed without being affected by the order of image formation, and the image forming efficiency can be improved.

If the size of the original placed on the automatic document feeder is larger than the reference image size, five planes of image memory are prepared in monochromatic conversion, and the timing of reading the (N + 1) th original is In the case of the full-color mode, the image reading operation is started by starting the image formation of the third color of the N-th document, thereby forming an image of a document larger than the reference size A4, such as the A3 size. Can be continuously performed, and the copying operation can be performed quickly to improve the productivity.

When the start of copying is instructed in the automatic color selection mode, if the size of the original placed on the automatic document feeder is smaller than the reference image size, 10 planes of image memory are prepared in monochromatic conversion. And an odd number (2N +
1) In the full-color mode, the timing of the reading operation of the original of the page is such that the original reading operation is started by starting the imaging of the first color of the 2Nth original, and the even-numbered (2N + 2) -th page is read. In the full-color mode, the original reading operation is started by forming an image of the third color of the 2N-th original in the full-color mode. It is possible to form an image in a targeted manner, and to enhance the productivity of copying.

Further, when the copy start is instructed in the automatic color selection mode, if the size of the document placed on the automatic document feeder is smaller than the reference image size, eight planes of image memory are prepared in monochromatic conversion. And an odd number (2N +
1) In the case of the full-color mode, the timing of the reading operation of the original of the page is such that the original reading operation is started by the start of the imaging of the second color of the 2N-th original, and the even-numbered (2N + 2) -th page In the full-color mode, the document reading operation is started by starting the image formation of the final color of the 2N-th document, so that the images of a plurality of documents can be continuously read. In this way, it is possible to increase the productivity of copying, and to reduce the storage capacity of the image memory.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of a motor control unit of the sheet-through type duplex automatic document feeder.

FIG. 3 is a block diagram illustrating a configuration of a control unit of the printer engine.

FIG. 4 is an explanatory diagram illustrating an image reading process.

FIG. 5 is a time chart showing an operation when forming an image of an A3 size document.

FIG. 6 is a time chart showing a conventional operation when forming an image of an A3 size document.

FIG. 7 is a time chart illustrating an operation when forming an image of an A4 size document.

FIG. 8 is a time chart showing another operation when forming an image of an A4 size document.

[Explanation of symbols]

1; digital color copier, 2; printer engine,
3: Sheet-through type duplex automatic document feeder (SRAD
F), 4; image reading unit, 5; image forming unit,
6; primary transfer unit, 7; secondary transfer unit, 8; paper feed unit, 9; fixing unit, 51; photoconductor, 53;
Image writing unit, 54; color developing unit, 61; intermediate transfer belt, 101; document feed tray, 102; document discharge tray, 103;

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 1/04 106 H04N 1/04 DF term (Reference) 2H027 DB09 DE07 ED04 ED12 EE01 EE07 EE08 EE10 EF09 FA04 FA22 FA28 2H030 AA07 AD08 AD12 AD17 BB04 BB07 BB42 2H076 AA58 BA59 BA63 BA87 BB04 EA01 5C072 AA05 BA03 BA05 BA19 QA14 RA01 UA11 WA02 XA05

Claims (3)

[Claims] 1. A sheet-through type automatic document feeder capable of sequentially detecting the size of a document placed on a document table, and a color for reading an image of a document in a full-color mode and determining whether the read document is a color document. An image reading device having a determination function, an image memory for storing image signals of the read image for each color of yellow (Y), magenta (M), cyan (C), and black (K); , Yellow (Y), magenta (M), cyan (C), and black (K), an image forming unit that forms a visible image on the photosensitive member, and a reference image size formed on the photosensitive member. An image forming apparatus comprising: an image holding unit that can hold two toner images simultaneously on two surfaces; and transfers a visible image transferred to the image holding unit to a transfer sheet sequentially fed. If the copy placed in the automatic document feeder is larger than the reference image size when the copy start is instructed in the selection mode, five planes of the image memory are prepared in monochromatic conversion, and the (N + 1) th sheet is prepared. An image forming apparatus is characterized in that, in the full-color mode, the document reading operation is started by starting the formation of the third color of the N-th document in the full-color mode. 2. A sheet-through type automatic document feeder capable of sequentially detecting the size of a document placed on a document table, and a color for reading an image of a document in a full color mode and determining whether the read document is a color document. An image reading device having a determination function, an image memory for storing image signals of the read image for each color of yellow (Y), magenta (M), cyan (C), and black (K); , Yellow (Y), magenta (M), cyan (C), and black (K), an image forming unit that forms a visible image on the photosensitive member, and a reference image size formed on the photosensitive member. An image forming apparatus comprising: an image holding unit that can hold two toner images simultaneously on two surfaces; and transfers a visible image transferred to the image holding unit to a transfer sheet sequentially fed. When the copy start is instructed by-option mode, the automatic document feeder when: the placed image size original size is a reference to the image memory in a single color terms 1
The 0th plane is prepared, and the timing of the reading operation of the odd-numbered (2N + 1) th page of the original is started in the full color mode by starting the imaging of the first color of the 2Nth original. The timing of the reading operation of the even-numbered (2N + 2) -page document is such that in the full-color mode, the document reading operation is started by starting the image formation of the third color of the 2N-th document. Image forming apparatus. 3. A sheet-through type automatic document feeder capable of sequentially detecting the size of a document placed on a platen, and a color for reading an image of a document in a full-color mode and determining whether the read document is a color document. An image reading device having a determination function, an image memory for storing image signals of the read image for each color of yellow (Y), magenta (M), cyan (C), and black (K); , Yellow (Y), magenta (M), cyan (C), and black (K), an image forming unit that forms a visible image on the photosensitive member, and a reference image size formed on the photosensitive member. An image forming apparatus comprising: an image holding unit that can hold two toner images simultaneously on two surfaces; and transfers a visible image transferred to the image holding unit to a transfer sheet sequentially fed. When the copy start is instructed by-option mode, if the document placed sizes automatic document feeder is less than the image size as a reference, an image memory in a single color conversion 8
A plane is prepared, and the timing of the reading operation of the odd-numbered (2N + 1) -th page original is started in the full-color mode by starting the image forming of the second color of the 2N-th page original, The timing of the reading operation of the document of the even-numbered (2N + 2) pages is such that, in the full color mode, the document reading operation is started by starting to form the final color of the 2Nth document. Forming equipment.