JP2001121788A - Color printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance whole throughput or the durability of a color printer even when a black and white color mixed document is printed and to reduce printing cost. SOLUTION: A color printer receives printing data from a PC client to start a printing job, stores the printing data in a memory device and forms image data on the basis of the printing data. A black and white printing mode is set as a printing mode by the start of the printing job and, when color printing data is contained in the printing data of a certain page (printing page) in the memory device the black and white printing mode is changed over to a color printing mode and the image data formed on the basis of the printing data is sent to an engine to perform printing in the color printing mode, and printing due to the color printing mode is repeated on and after. That is, the changeover from the color printing mode to the black and white printing mode is prohibited during the performance of one printing job.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color printing apparatus such as a color laser printer, a digital color copier, and a digital color multifunction machine.

[0002]

2. Description of the Related Art As a color printing apparatus such as a color laser printer, C (cyan), M (magenta), Y (yellow)
The switching of the printing mode between the color printing mode in which printing is performed using four colors of K (black) or the black and white (monochrome) printing mode in which printing is performed using only K is performed every time one page (one sheet) is printed. A method of automatically determining the type of print data (whether the print data includes only black-and-white print data or whether the print data includes color print data), and the above-described print mode switching. There has been proposed a method for performing the job automatically on a job-by-job basis.

A printing method in a color printing mode (however, a printing method using electrophotography) is a process of generating a one-color toner image on one photosensitive drum and transferring the toner image to an intermediate transfer belt. Is repeated for each color to generate a four-color superimposed toner image, and then the four-color superimposed toner image is collectively transferred onto one sheet of paper (1).
Drum method) and a method of simultaneously generating toner images of each color on four photosensitive drums and then sequentially transferring the toner images of each color onto one sheet of paper (four-drum method).

In the one-drum system, in order to perform printing in the color printing mode, the transfer process (transfer of the toner image from the photosensitive drum to the intermediate transfer belt) must be performed four times. In order to perform printing, only one transfer process is required, so that there is a great speed advantage. In most cases, printing in black and white print mode can be completed about four times faster than in color print mode.

[0005] In the case of the four-drum system, since there is usually no difference in speed as compared with the one-drum system, the advantage of automatically switching the printing mode between the color printing mode and the black-and-white printing mode is as follows. Than in terms of speed,
There are merits in extending the durable life of moving parts and the like and reducing printing costs.

Here, restrictions on the color printing apparatus using the four-drum system are described below. In this color printing apparatus, when printing is performed in the black-and-white printing mode, only the K toner image is generated on the K photoconductor drum, and the K toner image is generated.
Is transferred onto one sheet of paper by a transfer device for other colors (CMY) at that time, and in many cases, the transfer device for another color (CMY) is not operated. This is because the durability of the components is taken into consideration, and the printing process is different, for example, there is a difference in printing speed between the monochrome printing mode and the color printing mode.

Therefore, when the print mode is switched to the black-and-white print mode or the color print mode, some switching operation on the machine occurs, and the performance is reduced more than the normal print speed. Further, by performing many mechanical switchings, the number of switchings guaranteed by the mechanical part (part) of the apparatus is used in a short period of time.

In consideration of such a point, when printing a black-and-white image while reducing the number of times of switching the print mode as much as possible, the K-mode is preferably set to the black-and-white print mode.
It is desirable to be able to print in a single color. Here, ordinary documents to be printed are roughly classified into a black-and-white document composed of a black-and-white image, a color document composed of a color image, and a monochrome-color mixed document in which a black-and-white image and a color image are mixed. Is done.

[0009]

In the above-described color printing apparatus using the four-drum system, a printing mode is automatically switched by discriminating the type of print data every time one page is printed. When used, depending on the document to be printed, there is a problem in that switching the print mode conversely lowers the performance or lowers the durability of the device (parts).

On the other hand, when a method of automatically switching the print mode for each job is used, a color image may be printed as a black and white image, or a black and white image may be printed in the color print mode. There are problems that the printing cost increases and that the durability of the apparatus is reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and is intended to be applied to a color printing apparatus such as a color laser printer, particularly, a color printing apparatus using a four-drum system, even when printing a monochrome mixed color document. It is an object to improve the throughput and durability of the apparatus and reduce the printing cost.

[0012]

SUMMARY OF THE INVENTION The present invention relates to a color printing apparatus having print mode switching means for automatically switching a print mode between a monochrome print mode and a color print mode in accordance with print data. In order to achieve the above, the following is characterized.

According to a first aspect of the present invention, there is provided a switching prohibition unit for prohibiting the switching from the color printing mode to the monochrome printing mode by the printing mode switching unit during execution of one print job.

According to a second aspect of the present invention, in the color printing apparatus of the first aspect, when the print mode switching unit switches from the monochrome print mode to the color print mode during execution of one print job. A prohibition canceling means for canceling the prohibition of switching from the color printing mode to the monochrome printing mode by the switching prohibiting means when the number of continuous printing pages using only the black and white print data reaches a predetermined number of pages after the switching. It is provided.

According to a third aspect of the present invention, in the color printing apparatus according to the first aspect, when a plurality of copies are designated for one print job, the print mode switching means executes the monochrome mode during execution of the print job. When the mode is switched from the print mode to the color print mode, a prohibition canceling unit is provided for canceling the prohibition of switching from the color print mode to the black and white print mode by the switch prohibition unit at a break of the copy after the change. is there.

According to a fourth aspect of the present invention, in the color printing apparatus of the first aspect, a storage means for accumulating a plurality of pages of print data, a plurality of copies are designated for one print job, and the plurality of pages of print data are stored. If the data is stored in the storage unit, the type of print data for each page is determined,
When it is recognized that the page of only the black and white print data is continuous for a predetermined number of pages or more, the printing is switched from the color print mode to the black and white print mode by the switching prohibiting means when the first page is printed. Is provided with a prohibition canceling means for canceling the prohibition of switching.

According to a fifth aspect of the present invention, in the color printing apparatus of the second or fourth aspect, a page number setting means for setting the predetermined number of pages is provided.

[0018]

Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 2 is a block diagram illustrating a configuration example of a printing system including a color printing apparatus embodying the present invention.

This printing system includes a color printing apparatus 1 such as a color laser printer, a digital color copying machine, and a digital color multifunction machine, and a PC (personal computer) client 10 which is a higher-level device (host device).
And a network 20 such as a LAN (local area network) connecting them.

In this embodiment, the color printing apparatus 1 is connected to the PC client 10 via the network 20. However, the present invention is not particularly limited to the network 20, and the color printing apparatus 1 is connected to the PC client 20 by any connection method. It should just be done.

The color printing apparatus 1 includes a CPU 2 and a ROM
3, a RAM 4, a storage device 5, and a display / input device 6. The CPU 2 is a central processing unit that totally controls the entire color printing apparatus 1 based on a program in the ROM 3, a mode instruction from the display / input device 5, and a command (such as a print command) from the PC client 10.

The ROM 3 is a read-only memory that stores fixed data including a program for operating the CPU 2. The RAM 4 is a readable and writable memory used as a work memory when the CPU 2 performs processing. This RAM 4 can also be used as a storage device 5.

The storage device 5 is a storage device such as a hard disk (HDD) built in the color printing device 1 or a storage device such as a floppy disk, a magneto-optical disk, or a CD-RW externally mounted. Various types of data such as print data (black and white print data or color print data) of a plurality of pages from 10 and image data created based on the print data can be stored.

The image data is assumed to be rasterized (bitmap). When the color printing apparatus 1 is a color printing apparatus including a scanner such as a digital color copying machine or a digital color multifunction peripheral, the storage device 5 can store image data (print data) from the scanner.

The display / input device 6 can display various information such as information for notifying the user (user) of the current state of the color printing device 1 and can input a mode instruction to the CPU 2.

Although not shown in FIG. 2, the color printing apparatus 1 also has an engine for printing an image on a sheet based on image data (print data). This engine uses the aforementioned four-drum system. The PC client 10 includes the color printing device 1
Has a function of issuing a print instruction to the printer and transmitting print data.

Hereinafter, the processing according to the present invention by the CPU 2 of the color printing apparatus 1 will be specifically described with reference to FIGS. First, the color printing device 1
The processing according to the first aspect of the present invention by the CPU 2 will be described. The CPU 2 operates according to the program in the ROM 3 to realize the functions as the print mode switching unit and the switching prohibition unit according to the first aspect.
The process according to the invention can be performed.

FIG. 1 is a flow chart showing an example of processing according to the first embodiment of the present invention by the CPU 2 of the color printing apparatus 1. When receiving the print data from the PC client 10 via the network 20, the CPU 2 of the color printing apparatus 1 starts a print job. Then, the print data received from the PC client 10 is stored in the storage device 5, and rasterized image data is created based on the print data.

Further, the processing of FIG. 1 is performed in parallel with this processing. That is, it is first determined in step S1 whether or not the print job has been started. If the print job has been started, the monochrome print mode is set as the print mode in step S2, and the first page in the storage device 5 is set in step S3. It is determined whether or not the print data (print page) includes only black and white print data or whether the print data includes color print data.

If the print data of the first page is composed only of black and white print data, the image data created based on the print data is sent to the engine in step S6 to print in black and white print mode. Let them do
In step S7, it is determined whether one print job has been completed (printing of all pages has been completed), and if one print job has been completed, the processing in FIG. 1 ends.

If one print job has not been completed yet, the flow returns to step S3 to determine whether the print data of the second page in the storage device 5 is composed of only black and white print data, It is determined whether or not the print data includes color print data. If the print data also includes only black and white print data, image data created based on the print data is sent to the engine in step S6, and the monochrome print mode is set. To perform printing, and thereafter, the same processing as described above is repeated.

On the other hand, when the print data of the first or second page in the storage device 5 includes color print data,
In step S4, the print mode is switched from the black-and-white print mode to the color print mode, and image data created based on the print data is sent to the engine to perform printing in the color print mode. In step S5, one print job is executed. It is determined whether the process has been completed.

If one print job has not been completed yet, the flow returns to step S4, where the image data created based on the print data of the next page in the storage device 5 is sent to the engine to perform color printing. The printing is performed in the mode, and it is determined again in step S5 whether one print job is completed, and thereafter, the same processing as described above is repeated.

As described above, if the print mode is switched from the monochrome print mode to the color print mode once during the execution of one print job, the print mode cannot be returned to the monochrome print mode thereafter (the remaining print pages). I have. That is,
During execution of one print job, switching from the color print mode to the black and white print mode is prohibited.

Accordingly, of the print pages of one print job, for example, the first to fifth pages are black and white print pages (consisting of only black and white print data), and the sixth to seventh pages are color print pages ( (Including color print data), when pages 8 to 17 are monochrome print pages, and when pages 18 to 20 are color print pages (black and white color table of FIG. 6 according to the invention of claim 4 described later) When the process of FIG. 1 is executed, the first to fifth pages are printed in the black-and-white print mode, and the sixth to twentieth pages are printed in the color print mode. Will be.

Next, the processing according to the second aspect of the present invention performed by the CPU 2 of the color printing apparatus 1 will be described. In addition,
The CPU 2 operates according to the program in the ROM 3 to realize the functions of the print mode switching means, the switching prohibition means, and the prohibition canceling means of the first and second aspects, and performs the processing according to the second aspect of the invention. it can.

FIG. 3 is a flowchart showing an example of the processing according to the second aspect of the present invention performed by the CPU 2 of the color printing apparatus 1. When receiving the print data from the PC client 10 via the network 20, the CPU 2 of the color printing apparatus 1 starts a print job. Then, the print data received from the PC client 10 is stored in the storage device 5, and rasterized image data is created based on the print data.

The processing of FIG. 3 is performed in parallel with this processing. However, the processing of steps S11 to S15, S20, and S21 is the same as the processing of steps S1 to S7 of FIG. The description will be omitted, and each process after step S16 will be mainly described.

If it is determined in step S15 that one print job has not been completed, the print data (print page) of the next page (second page) in the storage device 5 is printed in black and white in step S16. It is determined whether the print data includes only data or whether the print data includes color print data. If the print data includes color print data, the following process is performed.

That is, in step S19, the count value of the black-and-white print counter is reset to "0", and in step S1
Returning to step 4, the image data created based on the print data of the second page is sent to the engine to perform printing in the color print mode. If the print data of the second page is composed of only black and white print data, step S1
At step 7, "1" is added to the count value of the monochrome print counter.

Next, it is determined whether or not the count value of the monochrome print counter has become "3". If the count value has not become "3", the flow returns to step S14 to return to the image created based on the print data of the second page. The data is sent to the engine and printing is performed in the color printing mode. After that, when the count value of the black and white printing counter becomes “3” (after the color printing mode is switched, the number of continuous printing pages using only the black and white printing data is reduced. The process proceeds to step S20 (when the number reaches "3 (predetermined predetermined number of pages)").

In step S20, the prohibition of switching from the color printing mode to the monochrome printing mode is released, and the printing mode is switched from the color printing mode to the monochrome printing mode.
The image data created based on the print data (black and white print data) of a certain page in the storage device 5 is sent to the engine to perform printing in the black and white print mode, and step S
At 21, it is determined whether one print job has been completed, and thereafter the same processing as described above is performed.

As described above, when the monochrome print mode is switched to the color print mode during execution of one print job, the number of continuous print pages using only monochrome print data is changed to "3 (others)". Is reached)), the prohibition of switching from the color print mode to the monochrome print mode is released, and the print mode is switched from the color print mode to the monochrome print mode.

Accordingly, of the print pages of one print job, for example, the first to fifth pages are black and white print pages (consisting of only black and white print data), and the sixth to seventh pages are color print pages ( If the 8th to 17th pages are monochrome printing pages, and the 18th to 20th pages are color printing pages (corresponding to id = 3 in the monochrome color table in FIG. 6), When the process of FIG. 3 is executed, 1
11th page to 5th page in black and white print mode, 6th page to 10th page in color print mode, 11 pages
From page 17 to page 17 in black and white print mode,
To the 20th page in the color print mode.

Next, the processing according to the third aspect of the present invention performed by the CPU 2 of the color printing apparatus 1 will be described. In addition,
The CPU 2 operates according to the program in the ROM 3 to realize the functions of the print mode switching means, the switching prohibition means, and the prohibition canceling means of the first and third aspects, and performs the processing according to the third aspect of the invention. it can.

FIG. 4 is a flowchart showing an example of the processing according to the third aspect of the present invention performed by the CPU 2 of the color printing apparatus 1. When a plurality of copies are designated for one print job from the PC client 10 via the network 20 and print data is received from the PC client 10 via the network 20, the CPU 2 of the color printing apparatus 1 Print job). Then, the print data received from the PC client 10 is stored in the storage device 5, and rasterized image data is created based on the print data.

The processing of FIG. 4 is performed in parallel with this processing. However, since the processing of steps S31 to S35, S37, and S38 is the same as the processing of steps S1 to S7 of FIG. Almost omitted, the description will focus on the processing of step S36. If it is determined in step S35 that one print job (print job of the designated number of copies) has not been completed, it is determined in step S36 whether printing of one copy has been completed.

If the printing of one part has not been completed yet, the flow returns to step S34 to return to the image data created based on the print data of the next page (second page) in the storage device 5. Is sent to the engine to perform printing in the color print mode, but when printing of one part is completed (at a break between copies after switching of the color print mode), the process returns to step S33 (from the color print mode to the monochrome print mode). Remove the prohibition of switching to).

Then, it is determined again whether the first page of print data (print page) in the storage device 5 is composed of only black and white print data or whether the print data includes color print data. The same processing as is performed.

As described above, when a plurality of copies are designated for one print job, when the mode is switched from the monochrome print mode to the color print mode during execution of the print job, the switching is performed. The prohibition of switching from the color print mode to the black-and-white print mode is released at the break of the subsequent copy, and the print mode of the second copy and thereafter can be switched from the color print mode to the black-and-white print mode.

Next, the processing according to the fourth aspect of the present invention performed by the CPU 2 of the color printing apparatus 1 will be described. In addition,
The CPU 2 operates in accordance with the program in the ROM 3 to realize the functions of the print mode switching means, the switching prohibition means, and the prohibition canceling means of the first and fourth aspects, and performs the processing according to the fourth aspect of the invention. it can.

FIG. 5 is a flowchart showing an example of the processing according to the fourth aspect of the present invention performed by the CPU 2 of the color printing apparatus 1. When a plurality of copies are designated for one print job from the PC client 10 via the network 20 and print data is received from the PC client 10 via the network 20, the CPU 2 of the color printing apparatus 1 Print job). Then, the print data received from the PC client 10 is stored in the storage device 5, and rasterized image data is created based on the print data.

When the print data received from the PC client 10 includes a plurality of pages and the print data of all the pages is stored in the storage device 5, the type of the print data for each page is determined. That is, it is determined whether the print data of each page is composed of only black and white print data or whether each of the print data includes color print data. Then, a management table (monochrome color table) as shown in FIG. 6 is created.

Here, in the monochrome color table shown in FIG. 6, the data of id = 1 indicates that any of the print data of pages 1 to 20 includes color print data (color image data). ing. The data of id = 2 indicates that each of the print data of pages 1 to 30 is composed of only black and white print data (black and white image data).

In the data of id = 3, the print data of the first page to the fifth page is composed of only monochrome print data, the print data of the sixth page to the seventh page include the color print data, This indicates that the print data from the 17th page to the 17th page is composed of only black and white print data, and the print data from the 18th to 20th pages includes color print data.

The data of id = 4 indicates that the print data of the first page includes the color print data, and the print data of the second to third pages is constituted only by the monochrome print data. .

The CPU 2 of the color printing apparatus 1 further performs the processing of FIG. 5 in parallel with the above-described processing.
The processes in S41 to S44, S48, and S49 are the same as the processes in steps S1 to S4, S6, and S7 in FIG. 1, and thus the description thereof is omitted, and the description will focus on the processes in and after step S45. Go.

At step S44, the image data generated based on the print data of a certain page (second page) in the storage device 5 is sent to the engine to perform printing in the color print mode. Then, it is determined whether or not the pages (black and white pages) including only the black and white print data are continuous over a predetermined number of pages (set number of pages) based on the previously created black and white color table.

If the pages of only the black and white print data are not continuous beyond a predetermined number of pages, it is determined in step S46 whether one print job (the specified number of print jobs) has been completed. If one print job has not been completed, it is determined in step S47 whether or not printing of one part has been completed. If printing of one part has not been completed yet, the flow returns to step S44 to return to the storage device. The image data created based on the print data of the next page in 5 is sent to the engine to perform printing in the color print mode.

When the printing of one copy is completed (at a break between copies after the color print mode is switched), the process returns to step S43 (the prohibition of switching from the color print mode to the monochrome print mode is released). Alternatively, step S
Even if it is determined (recognized) that the pages of only the black and white print data continue more than a predetermined number of pages in 45, the process returns to step S43 (the first page of the pages of only the continuous black and white print data is printed). At the same time, the prohibition of switching from the color print mode to the black and white print mode is released).

As described above, when a plurality of copies are designated for one print job and print data of a plurality of pages is stored in the storage device 5, the type of print data for each page is determined. If it is recognized that the page of only the black and white print data is continuous for a predetermined number of pages (here, “3”, but another value may be used), the first page is printed. When switching from color print mode to black and white print mode,
The subsequent print modes can be switched from the color print mode to the monochrome print mode.

Accordingly, of the print pages of one print job, for example, the first to fifth pages are black and white print pages (consisting of only black and white print data), and the sixth to seventh pages are color print pages ( If the 8th to 17th pages are monochrome printing pages, and the 18th to 20th pages are color printing pages (corresponding to id = 3 in the monochrome color table in FIG. 6), When the process of FIG. 5 is executed, 1
Pages 5 to 5 are in black and white print mode, pages 6 to 7 are in color print mode, pages 8 to 17 are in black and white print mode, and pages 18 to 20 are in color print mode. To perform printing.

Note that the comparison value (predetermined number of pages) used in step S18 in FIG. 3 or step S45 in FIG.
The optimal value of the set number of pages (predetermined number of pages) used by the printer greatly depends on the characteristics of the document to be printed, the characteristics of the color printing apparatus, and the like. Therefore, the predetermined number of pages can be arbitrarily set by an operation signal from the display / input device 6 (corresponding to the invention of claim 5). Then, an optimal value that depends on the environment can be set as the predetermined number of pages. An optimum value that depends on the environment can be set as the predetermined number of pages by a command from an external device such as the PC client 10 or the like.

[0064]

As described above, according to the present invention, in a color printing apparatus using a four-drum system,
Even when printing a black-and-white color mixed document, switching from the color printing mode to the black-and-white printing mode is prohibited during the execution of one print job, so that the overall throughput (printing speed) and the durability of the apparatus are improved. In addition, printing costs can be reduced.

Further, according to the second aspect of the present invention, when switching from the monochrome printing mode to the color printing mode during execution of one print job, continuous printing using only the monochrome printing data is performed after the switching. When the number of pages reaches a predetermined number, the prohibition of switching from the color print mode to the black-and-white print mode is released, and the print mode can be switched from the color print mode to the black-and-white print mode. Can be improved, and the printing cost can be further reduced.

According to the third aspect of the present invention, when a plurality of copies are designated for one print job, the mode is switched from the monochrome print mode to the color print mode during execution of the print job. In this case, the prohibition of switching from the color print mode to the black-and-white print mode was released at the break of the copy after the switch, and the print mode for the second copy and later could be switched from the color print mode to the black-and-white print mode. It is also possible to guarantee that the copies are printed under the same printing conditions.

According to the fourth aspect of the present invention, when a plurality of copies are designated for one print job and a plurality of pages of print data are stored in the storage means (in a case where electronic sort printing is performed), the number of copies is determined. If the type of the print data for each page is determined and it is recognized that the page of only the black and white print data is continuous for a predetermined number of pages or more,
The prohibition of switching from the color print mode to the black and white print mode when the first page is printed is released, and the subsequent print modes can be switched from the color print mode to the black and white print mode. The mode can be switched.

According to the fifth aspect of the present invention, the predetermined number of pages according to the second or fourth aspect can be arbitrarily set (changed), so that a more optimal print mode can be switched under different environments. be able to.

[Brief description of the drawings]

FIG. 1 is a flowchart showing an example of processing according to the invention of claim 1 by a CPU 2 of the color printing apparatus 1 shown in FIG.

FIG. 2 is a block diagram illustrating a configuration example of a printing system including a color printing apparatus embodying the present invention.

FIG. 3 is a flowchart showing an example of processing according to the second embodiment of the present invention performed by the CPU 2 of the color printing apparatus 1 shown in FIG. 2;

FIG. 4 is a flowchart showing an example of a process according to the invention of claim 3;

FIG. 5 is a flowchart showing an example of a process according to the invention of claim 4;

FIG. 6 is a diagram illustrating an example of a management table (black and white color table) used in the processing of FIG. 5;

[Explanation of symbols]

 1: color printing device 2: CPU 3: ROM 4: RAM 5: storage device 6: display / input device 10: PC client 20: network

Continued on the front page F term (reference) 2C061 AP01 AP04 AP07 AQ06 AR01 AS02 HH08 HK03 HN15 2H027 DA46 EB04 EC20 EE07 EE08 EF09 FA28 FA35 ZA08 2H030 AD07 AD13 5C074 AA20 BB03 BB17 CC26 DD16 DD21 EE08 FE11 MA14 H04H MA11 MA17 NA13 NA25 PA02 PA03

Claims (5)

[Claims] 1. A color printing apparatus having a print mode switching means for automatically switching a print mode between a monochrome print mode and a color print mode in accordance with print data. A color printing apparatus comprising: a switching prohibition unit that prohibits a mode switching unit from switching from a color printing mode to a monochrome printing mode. 2. The color printing apparatus according to claim 1, wherein when the print mode switching unit switches from a monochrome print mode to a color print mode during execution of one print job, the switching is performed thereafter. Prohibition canceling means for canceling the prohibition of switching from the color printing mode to the black and white printing mode by the switching prohibiting means when the number of continuous printing pages using only black and white print data reaches a predetermined number of pages. A color printing device characterized by the above-mentioned. 3. The color printing apparatus according to claim 1, wherein when a plurality of copies are designated for one print job, the print mode switching unit switches from the black and white print mode during execution of the print job. When switching to the color printing mode is performed, a prohibition canceling unit for canceling the prohibition of switching from the color printing mode to the black and white printing mode by the switching prohibiting unit at a break of the copy after the switching is provided. Color printing device. 4. The color printing apparatus according to claim 1, wherein a storage unit for storing print data of a plurality of pages, a plurality of copies are designated for one print job, and the print data of a plurality of pages are stored in the storage unit. If it is stored, the type of the print data for each page is determined, and if it is recognized that the pages of only the black and white print data are continuous for a predetermined number of pages or more, the first page is read. And a prohibition canceling means for canceling the prohibition of switching from the color printing mode to the black-and-white printing mode by the switching prohibiting means when printing is performed. 5. The color printing apparatus according to claim 2, further comprising a page number setting unit for setting the predetermined number of pages.