JPH1039570A - Color image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase a recording speed in a state where the capacity of a memory for preserving print data (color image information) is small by controlling the actuation interval of respective image forming units based on the attribute of the color image information. SOLUTION: By a control unit 30, the print data produced by a print data producing unit 31 and the attribute data thereof are inputted. When the print data is decided to be identical to that of a former page based on the attribute data, for example, the print data of the final color (cyan) of the former page is transferred to an exposure circuit 40C and the print data of the first color (black) of a concerned page is started to be transferred to an exposure circuit 40K by the unit 30 before a recording action is finished. In such a case, the actuation interval of the respective recording units can be set to be the minimum time decided by the mechanical performance thereof. The print data of the former page (identical to the print data of this time) is always stored in a RAM 32.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image forming apparatus such as a color copying machine and a color printer for forming a multicolor image by superposing a plurality of monochromatic images.
More specifically, the present invention relates to a color image forming apparatus capable of continuously forming a color image as quickly as possible.

[0002]

2. Description of the Related Art A so-called tandem type full-color image forming apparatus as shown in FIG. 9 has been conventionally known as this type of color image forming apparatus. The full-color image forming apparatus includes a sheet conveying device 1, a plurality of image forming units 2a, 2b, 2c, and 2d, a sheet cassette 3, a fixing unit 4, a sheet discharge tray 6, and a belt cleaning unit 12. The sheet transporting apparatus 1 has a transport belt 11 that is driven to circulate, and the recording sheets 5 from the paper feed cassette 3 are moved toward the discharge tray 6 by the transport belt 11 that is driven to circulate. ing.

The image forming units 2a, 2b, 2c, 2d
It is provided so as to face the conveying surface of the recording sheet 5 of the conveying belt 11, and each of the black (K) and the black (K) according to the electrophotographic process.
Yellow (Y), magenta (M), and cyan (C) color images are sequentially superimposed and formed on the recording sheet 5. in this way,
A full-color image (multicolor image) is formed on the recording sheet 5 by superimposing the images of each color. The recording sheet 5 conveyed by the conveyance belt 11 is discharged to the paper discharge tray 6 through the fixing unit 4 after a full-color image is formed.

Each image forming unit 2a, 2b, 2c, 2d
In order to realize a general electrophotographic process, a photosensitive drum 21 (latent image carrier), a charger 22, an exposure unit 23,
It has a developing device 24, a cleaning device 25, and a transfer device 26. The developing device 24 stores a developer (toner) of a color of an image to be formed. The fixing unit 4 has a heat roll 41 for heating and a pressure roll 42 for pressure in order to thermally fix a developer (toner) for forming a color image on the recording sheet 5.

In the tandem type image forming apparatus having the above structure, each of the image forming units 2a, 2b, 2c,
The black image (K), the yellow image (Y), the magenta image (M), and the cyan image (C) formed in 2d are overlapped on the conveyed recording sheet, for example, as shown in FIG.
The formation timing of each color image is shifted. Further, it is usually necessary to hold the print data from the start of recording the first color image (black image) to the time when the recording sheet on which the color image is formed is discharged in consideration of the jam of the recording sheet. is there.

In the example shown in FIG. 10, after a multi-color image for one page is recorded on a recording sheet, a multi-color image for the next page is recorded on the next recording sheet. In this case, the print data for one page (print data for four colors) is stored in the RAM.
And so on until the recording of the multicolor image based on the print data is completed. Therefore, even if a jam of the recording sheet occurs while each color image is being recorded on the recording sheet, the multicolor image is again recorded on another recording sheet using the print data stored in the image memory. Can be recorded.

[0007]

When the recording of the multicolor image of the next page is started after the multicolor image of one page is recorded as described above, the image forming units 2a, 2a
Although b, 2c and 2d can be operated at intervals of time t _min determined by their mechanical performance, they are operated at intervals of time t longer than that (see FIG. 10). That is, when a recording sheet jam occurs, the recording speed is sacrificed to enable re-recording.

In order to perform a recording operation (printing operation) on a continuous recording sheet, in order to operate each image forming unit at a time interval as close as possible to a time t _min determined by their mechanical performance, It is necessary to store print data for a plurality of pages. In this way, even if the operation interval of each image forming unit is reduced and the image recording of the next page is started before the image recording of the previous page is completed, the image is saved when a recording sheet jam occurs. The reprint can be performed by the print data. The greater the number of pages of print data to be stored, the closer the operation interval of each image forming unit can be to the time t _min determined by their mechanical performance.

However, as described above, when the number of pages of print data to be stored is increased, the capacity of a memory for storing the print data must be increased. That is, an expensive memory having a large capacity is required to enable re-recording when a recording sheet jam occurs. Therefore, an object of the present invention is to provide a color recording medium capable of increasing the recording speed as much as possible while minimizing the capacity of a memory for storing print data for enabling re-recording when a recording sheet jam occurs. It is to provide an image forming apparatus.

[0010]

In order to solve the above-mentioned problems, the present invention is described in claim 1 and, as shown in FIG. 1, a recording sheet 1 based on supplied color image information.
01, 100 (1), 100 (2),..., 100 (n)
, The image forming units 100 (1), 100 (2),...
, 100 (n) for temporarily storing color image information to be supplied to each of the image forming units 100 (1), 100 (2),..., 100 (n).
A color image based on the color image information is formed in a predetermined order on the recording sheet 101 on which the multi-color image moves.
01, the image forming units 100 (1), 100 (2),...
.., An attribute determining means 104 for determining an attribute which affects the storage capacity of the color image information to be supplied to 100 (n) in the memory unit 102;
When performing image recording on the image forming unit 1, the image forming units 100 (1), 1
.., 100 (n).

In the above color image forming apparatus, each of the image forming units 100 (1), 100 (2),.
When a color image based on the color image information is formed in a predetermined order on the recording sheet 101 to which 100 (n) moves,
When a jam of the recording sheet 101 occurs, it is possible to re-record a color image based on the color image information stored in the memory unit 102.

When recording images on the recording sheet 101 continuously, each of the image forming units 100 (1), 10 (1),
The operation intervals for providing color image information to 0 (2),..., 100 (n) for operation are not always constant, and the image forming units 100 (1), 100 (2),.
The control is performed based on the attribute of the color image information provided to 100 (n). The attribute of the color image information is
2 is an attribute that affects the storage capacity of the storage device. If the color image information has an attribute that increases the storage capacity of the memory unit 102, each image forming unit 100 (1)
The interval for operating 100 (2),..., 100 (n) becomes longer. Thereby, the memory unit 102
The number of recordings (for example, the number of pages) that can be performed using the color image information stored in the image forming unit 1 is small.
Since the operation intervals of 00 (1), 100 (2),..., 100 (n) become longer, even if a jam of the recording sheet 101 occurs, an image is formed using the color image information stored in the memory unit 102. Re-recording can be enabled.

On the other hand, each of the image forming units 100 (1),
If the color image information supplied to 100 (2),..., 100 (n) has an attribute that reduces the storage capacity in the memory unit 102, each image forming unit 100
(1), 100 (2),..., 100 (n) can be operated at shorter intervals. In this case, the number of recordings (for example, the number of pages) that can be performed using the color image information stored in the memory unit 102 increases, so that each of the image forming units 100 (1), 100 (2),.
Even if the interval for operating 100 (n) is short, when a recording sheet 101 jams, image reprinting can be performed using the color image information stored in the memory unit 102.

Here, attributes that affect the storage capacity of the color image information in the memory unit 102 include a recording sheet size used, a color image data size, and an attribute used for actual image formation among a plurality of image forming units. Color image information to be supplied to the image forming unit, whether or not the color image information is the same as the color image information used to form the image on the previous recording sheet, and information such as the resolution of the image to be recorded. That is, when the used recording sheet size is small, when the color image data size is small, and when the color image information to be supplied to the image unit used for actual image formation among the plurality of image forming units is small,
The number of image recordings (for example, the number of pages) that can be performed using the color image information stored in the memory unit increases.

If the same color image information is used for forming an image on the previous recording sheet, it is not necessary to store new color image information in the memory unit when forming an image on the next recording sheet. As a result, image recording 1 on a recording sheet
The storage capacity of color image information per time is reduced. Therefore, information on whether the color image is the same as the color image used to form the image on the previous recording sheet can be included as an attribute that affects the storage capacity of the color image information in the memory unit. Further, when the resolution of the image to be recorded is low, the number of image recordings (for example, the number of pages) that can be performed using the color image information stored in the memory unit increases.

In the above-mentioned color image forming apparatus, from the viewpoint of simplifying the control by the control means 106, the control means 106 is provided with a terminal for forming the previous multicolor image. After supplying the color image information to the image forming unit corresponding to the color image, the first mode for starting the operation of each image forming unit to form the next multicolor image, and the previous multicolor image Before providing the color image information to the image forming unit corresponding to the final color image to be formed, starting the operation of the image forming unit to be operated at least first to form the next multicolor image It is possible to have a mode switching means for switching one of the two modes based on the determination result from the determination means.

In such a color image forming apparatus, when the storage capacity of the color image information in the memory unit is large, the mode is switched to the first mode, which corresponds to the last color image for forming the previous multicolor image. After the color image information is supplied to the image forming unit, the operation of each image forming unit is controlled so that the operation of each image forming unit is started to form the next multicolor image. As a result, the operation interval of each image forming unit becomes relatively long. On the other hand, when the storage capacity of the color image information in the memory unit is small, the mode is switched to the second mode, and the color image information is stored in the image forming unit corresponding to the final color image for forming the previous multicolor image. Before providing, the operation of each image unit is controlled so as to start the operation of the image forming unit to be operated at least first to form the next multicolor image. As a result, the operation interval of each image forming unit becomes relatively short.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. For example, a tandem type image forming apparatus having a structure as shown in FIG. 9 will be described as an example.
The control system in the tandem type image forming apparatus is configured as shown in FIG. 2, for example. 2, the control system includes a control unit 30, a print data generation unit 31, a RAM 32, and a sheet conveyance drive unit 33. The control system further includes exposure circuits 40K, 40Y, 40M, and 40C corresponding to the respective image forming units 2a, 2b, 2c, and 2d. The print data generating unit 31 outputs the image information from the image information providing unit 50 for each color (black, yellow, magenta, cyan) to be provided to each of the exposure circuits 40K, 40Y, 40M, and 40C corresponding to each image forming unit. Convert to print data (color image information). The image information providing unit 50 is, for example, an image reading device when the color image forming apparatus is applied to a copying machine. In this case, the RGB image data provided from the image reading device is converted into the print data (K, Y, M, C). When the color image forming apparatus is applied to a color printer, the image information providing unit 50 is a host computer.

The print data generating unit 31 also generates attribute data of the generated print data. The attribute data includes, for example, data on whether the print data is the same as the print data of the previous page, data on whether print data for forming a multi-color image (print data of a plurality of colors) or print data for forming a single-color image, Contains data on resolution. The print data of each color generated by the print data generation unit 31 is stored in the RAM 32 in preparation for a re-recording process at the time of a recording sheet jam. The sheet conveyance drive unit 33 drives the conveyance belt 11 of the sheet conveyance device 1 (see FIG. 9) at a constant speed.

The control unit 30 controls the transfer of the print data generated by the print data generation unit 31 to each of the exposure circuits 40K, 40Y, 40M, and 40C, the drive control of the sheet transport drive unit, and the print data generation unit 31. The control of storing print data from the RAM 32 in the RAM 32 is performed. The RAM 32 stores a predetermined recording size (for example, A
4 size) and has a capacity to store one page of print data. The control unit 30 further controls reprinting performed using the print data stored in the RAM 32 when a recording sheet jam occurs. Also, each of the exposure circuits 40K, 40Y, 40M, 40C of the print data
Is controlled based on the attribute data generated together with the print data in the print data generation unit 31. Each exposure circuit includes, for example, a buffer 41K (41Y, 41M, 41C) for holding print data transferred from the print data generating unit 31 for one line,
It has a drive circuit 42K (42Y, 42M, 42C) for controlling the drive of each exposure unit 23K (23Y, 23M, 23C) based on the print data stored in each buffer. When forming a multicolor image, the control unit 30 controls transfer of print data according to, for example, a procedure shown in FIG. In FIG. 3, when print data is generated by the print data generation unit 31, the control unit 30 inputs the attribute data that is generated at the same time (S1). Then, based on the attribute data, the control unit 30 determines whether the generated print data is the same as that of the previous page (S2), whether the generated print data is for a monochrome image (black image) as a pudding (S3), Is standard (H) or low density (L) (S4).

If the print data generated by the control unit 30 is different from that of the previous page and is not a monochrome image, but has a standard (H) resolution, the transfer control in mode A is performed. Is performed (P100). In the transfer control process (P100) in the mode A, the transfer timing of the print data of each color (K, Y, M, C) is controlled as shown in FIG. 6, FIG. 7, and FIG. That is, the print data of the final color (cyan) of the previous page is transferred to the exposure circuit 40C, and after the recording of the multicolor image of the previous page on the recording sheet is completed, the print data of the first color (black) of the page is completed. The transfer of the print data to the exposure circuit 40K is started. After that, the print data of the other colors is transferred to the corresponding exposure circuits 40Y, 40M, and 40C at predetermined intervals.

After the transfer processing of the print data is completely completed, the transfer processing of the print data of the next page is started. Therefore, even if a recording sheet jam occurs during the recording of the multicolor image, the next page is not affected. Before the recording of RAM3 starts
The multi-color image can be re-recorded using the print data for one page stored in the second print data. In this case, the operation interval of each image forming unit 2a, 2b, 2c, 2d is a time t (≧ t _min ) longer than the minimum time t _min determined based on their mechanical performance. On the other hand, when the control unit 30 determines that the print data generated by the control unit 30 is the same as that of the previous page, transfer control in mode B is performed (P200).

The transfer control processing in mode B in this case is as follows.
The transfer timing of the print data of each color (K, Y, M, C) is controlled as shown in FIG. That is, the print data of the final color (cyan) of the previous page is transferred to the corresponding exposure circuit 40C, and before the recording of the multicolor image of the previous page on the recording sheet is completed, the first color (cyan) of the page is completed. black)
The transfer of the print data to the corresponding exposure circuit 40K is started. In this case, each recording unit 2a, 2b, 2c,
The 2d operation interval can be set to a minimum time t _min determined by its mechanical performance. As described above, even if the operation interval of each recording unit is set to the minimum time t _min , the multi-color image is recorded because the print data of the previous page (the same as the present print data) is always stored in the RAM 323. Even if a recording sheet jam occurs on the way, reprinting can be performed using the print data stored in the RAM 32. Further, the control unit 30
However, when it is determined that the generated print data is that of a monochrome image, the transfer control in mode B is also performed (P200).

As shown in FIG. 7 (i), the time required to transfer the print data of each color is the same.
This is referred to as t _K. Further, the time lag at the start of the transfer of the print data of each color is also the same, and is set to Δt. For example, the reading speed of the image reading device as the image information providing unit 50 is 0.5 t per page for both the monochrome image and the multicolor image.
It is possible with _K, the print data generating unit 31 is to be processed in real time. In this case, when the following conditions are met, the image forming units 2a, 2b, 2c, the operation interval 2d can be set to the minimum time t _{m in} determined based on its mechanical performance.

In FIG. 7 (i), the time t _ALL required to transfer all the print data of four colors is expressed as t _ALL = t _K + 3Δt. Now, if Δt = 0.2t, t _ALL / t _K = 1.
6, that is, in one image, the time from the start of the transfer of the print data of the first color to the end of the transfer of the print data of the last color is 1.6 times the transfer time of the print data of one color.
Double. Next, the occurrence of a jam of the recording sheet is considered up to the discharge position of the recording sheet. Assuming that the time from the end of the transfer of the print data of the final color to the discharge of the recording sheet is 1.0Δt, the time from the start of the transfer of the print data of the first color to the discharge of the recording sheet in one image is one. It is 1.8 times the transfer time of print data for each color. That is,
In order to cope with the jam of the recording sheet and to control the operation interval of each image forming unit 2a, 2b, 2c, 2d to the minimum time _tmin , it is necessary to store at least two pages of print data in the RAM. There is.

As described above, when the generated print data is for a single color image (black image), its storage capacity is four times the storage capacity of the multicolor image print data (print data for four colors). It's a fraction. That is, print data of a single-color image can be stored in the RAM 32 for four pages. Therefore, in this case, it is possible to perform mode B transfer control on the generated print data of the monochrome image. In the transfer control process in the mode B in this case, the transfer timing of the print data of the single color (K) is as shown in FIG.
Is controlled as shown in FIG. That is, the print data of the single color (black) can be transferred to the corresponding exposure circuit 40K (image forming unit 2a) at the interval of the minimum time t _min after the transfer of the print data of the monochrome image of the previous page. . FIG. 5 shows the state of the control of the control unit 30 (print data transfer control and transport drive control) when the mode B is selected, for example. Furthermore, when the control unit 30 determines that the generated print data resolution is low density (L), the transfer control in mode B is also performed (P200). For example, the print data generation unit 3
In the case where the vertical density (resolution) and the horizontal density (resolution) of the image represented by the print data generated in step 1 are each half the standard (H) value, the storage capacity of the print data is This is one-fourth of the resolution print data. That is, print data for four pages can be stored in the RAM 32. On the other hand, assuming the same assumption as described with reference to FIG. 7, transfer control at intervals of the minimum time t _min is sufficient if print data for two pages is stored in the RAM 32. Therefore, in this case, transfer control in mode B can be performed.

The transfer control processing in mode B in this case is as follows.
The transfer timing of the print data of each color (K, Y, M, C) is controlled as shown in FIG. Thus, the print data of each color is stored in each of the image forming units 2a, 2b,
Transfer control is performed at intervals of a minimum time t _min determined by mechanical performances 2c and 2d. When a multi-color image is recorded by such transfer control of print data, 1
If the recording sheet of the page is jammed immediately before the end of the discharge, the print data of the first page remains in the RAM 32 even if the transfer of the print data for three pages has already been started. Re-recording of the first page becomes possible.

In the above-described example, the capacity of the RAM 32 for storing print data is limited to only storing print data corresponding to a multi-color image of one page. When continuously recording a multi-color image based on print data, the print data is transferred so that the transfer of the first color print data of the next page is started after the transfer of the final color print data is completed. Is performed (mode A). In addition, when recording a multi-color image continuously with the same print data, when recording a single-color image continuously, or when recording an image with a resolution lower than the standard resolution, RA
Since the number of pages of print data that can be stored in the M32 increases, the transfer of the first color print data of the next page is performed before the transfer of the final color print data is completed.
As a result, the operation interval of each image forming unit can be set to the minimum time t _min determined by its mechanical performance (mode B). Therefore, high-speed processing can be performed for continuous recording of the same image, recording of a single-color image, or recording of a low-resolution image.

In the above example, the capacity of the RAM 32 for temporarily storing the print data corresponds to one page of the print data of the multi-color image of the standard resolution. It is possible to have a storage capacity for a plurality of pages of print data of a color image. If so, the mode
The switching criterion between A and mode B may be different from that in the above example. Further, as in the above example, the transfer control is not limited to the two-stage (mode A and mode B) print data transfer control.
It is also possible to perform more detailed print data transfer control based on the attributes of the print data.

[0030]

As described above, according to the present invention, based on the attributes of the color image information (print data),
Since the operation interval of each image forming unit is controlled, when the color image information for many recording pages can be stored in the memory unit, the operation interval of each image forming unit can be shortened. As a result, it is possible to improve the recording speed of such a multicolor image based on the color image information.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the principle of the present invention.

FIG. 2 is a block diagram illustrating an example of a control system applied to the color image forming apparatus of the present invention.

FIG. 3 is a flowchart showing a procedure for determining a control mode in a control unit in the control system shown in FIG. 2;

FIG. 4 is a diagram illustrating an example of a processing procedure in mode B.

FIG. 5 is a diagram showing another example of the procedure of the process in mode B.

FIG. 6 shows print data transfer timing in mode A
FIG. 9 is a diagram showing a comparison between the mode and mode B.

FIG. 7 shows print data transfer timing in mode A
FIG. 9 is a diagram showing a comparison between the mode and mode B.

FIG. 8 shows print data transfer timing in mode A
FIG. 9 is a diagram showing a comparison between the mode and mode B.

FIG. 9 is a diagram illustrating a configuration example of a tandem type color image forming apparatus.

FIG. 10 is a diagram illustrating an example of a conventional print data transfer timing.

[Explanation of symbols]

100 (1), 100 (2), ..., 100 (n) ... image forming unit, 101 ... recording sheet, 102 ... memory unit, 104 ... attribute determination means, 106 ... control means

Claims (2)

[Claims] A plurality of image forming units for forming a corresponding color image on a recording sheet based on the supplied color image information; and a memory unit for temporarily storing color image information to be supplied to the image forming unit. A color image forming apparatus that forms a color image based on color image information in a predetermined order on a recording sheet on which each image forming unit moves, and records a multicolor image on the recording sheet. An attribute determining unit for determining an attribute that affects the storage capacity of the color image information to be supplied to the image forming unit in the memory unit; and an attribute determining unit for continuously recording an image on a recording sheet. And control means for controlling the operation interval of each image forming unit based on the result of the determination. 2. A color image forming apparatus according to claim 1, wherein said control means supplies said color image information to an image forming unit corresponding to a final color image for forming a previous multicolor image. A first mode for starting the operation of each image forming unit to form the next multicolor image, and a corresponding color image to the image forming unit corresponding to the final color image for forming the previous multicolor image. Before providing the information, any one of the second mode for starting the operation of the image forming unit to be operated at least first to form the next multi-color image is determined based on the determination result from the determination unit. A color image forming apparatus having mode switching means for switching.