JP2003080771A - Imaging apparatus and its controlling method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging apparatus employing a band memory, and its controlling method, in which print overrun can be prevented while sustaining a maximum print speed. SOLUTION: When a predicted time of generating the intermediate data of next page is larger than a predetermined value (S1060), a decision is made that the intermediate data of next page cannot be generated within the rendering time of intermediate data corresponding to current page and the intermediate data of next page is generated (S1065) before starting output of the bit map data of current page (S1100).

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a host computer.
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a printer connected to a printer or the like and a control method thereof, and more particularly, to an image forming apparatus that performs print processing in band units and a control method thereof.

[0002]

2. Description of the Related Art Conventionally, an image forming apparatus, for example, a printer such as a well-known laser beam printer is connected to a host computer by using a standard interface cable, and a drawing command described in PDL is input from the host computer. Then, a part called a controller interprets this drawing command, generates intermediate data in a storage device (page buffer), and then expands (renders) the intermediate data and outputs a binary value to the printer engine. Generate bitmap data. And
The bitmap data is output to the printer engine, and the print result is finally obtained from the printer.

In recent years, page printers typified by laser beam printers are required to have a high speed, and in particular, to achieve the maximum print speed when a plurality of pages are continuously output. In addition, high speed and low cost are required, and in order to reduce the internal memory capacity, which affects the cost, the laser beam printer, which is a page printer, also uses the bitmap data for one page like the serial printer. It does not have a memory (page memory) to store the data, draws bitmap data (hereinafter referred to as rendering) in a memory for a predetermined line smaller than one page, that is, a band memory, and synchronizes with the operation of the printer engine, Many products have adopted the banding processing method that outputs bitmap data.

When the banding processing method is used, since it is necessary to output bitmap data from the controller in synchronization with the printer engine, it is predicted in advance whether the rendering of the intermediate data will meet the printing speed of the printer engine, and the rendering is performed. If possible,
When the intermediate data for one page is generated, the controller outputs a print signal for notifying the printer engine of the output ready state.

[0005]

However, in the above-mentioned conventional example, since the rendering time of the intermediate data is predicted and it is determined whether or not the rendering is possible based on the predicted time, other factors, in particular, When reading and writing to the storage device (page buffer, band memory) due to other factors occurs, it takes a lot of time to read the intermediate data from the page buffer and to write and read the bitmap data after rendering to and from the band memory, As a result, there has been a problem that the output of the bitmap data from the controller cannot meet the processing speed of the printer engine (hereinafter, this phenomenon is referred to as print overrun).

As a solution to this problem, there is a method in which a bitmap memory for one page is generated and a bitmap for one page is generated and then output to the engine (= the same as the conventional page unit processing?). , First print (1
There is a problem in that the time from the start of printing the page to the end of discharging the paper is delayed and a huge amount of memory is required, resulting in an extremely high cost.

That is, while maintaining the maximum print speed,
In order to prevent the print overrun, it is necessary to predict the time to read the intermediate data from the page memory and the time to write to and read from the band memory in consideration of the read / write time of the storage device caused by the reading / writing of the storage device due to other factors. was there.

The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to provide an image forming apparatus using a band memory and a control method therefor, while maintaining a maximum print speed and printing over. An object of the present invention is to provide an image forming apparatus capable of preventing run and its control method.

[0009]

That is, the gist of the present invention is a printer controller that interprets input image information, generates predetermined intermediate data consisting of a plurality of bands, and expands it into printable bitmap data. An image forming apparatus comprising a printer engine for printing bitmap data on a recording material, wherein the printer controller has a first storage unit for storing intermediate data, and a second storage unit for storing bitmap data for a predetermined number of bands. Storage means of
Prediction means for generating intermediate data for the next page, predicting the intermediate data generation time required to write the generated intermediate data in the first storage means, and comparing the predicted time with a predetermined value, Is larger than a predetermined value, it has a control means for performing control so as to start outputting intermediate data bitmap data for the current page to the printer engine after the generation of intermediate data for the next page is completed. An image forming apparatus characterized by the above.

Another aspect of the present invention is a printer controller which interprets input image information, generates predetermined intermediate data composed of a plurality of bands, and expands it into printable bitmap data, and a bitmap data. An image forming apparatus including a printer engine for printing on a recording material, the printer controller including: first storage means for storing intermediate data; and second storage means for storing bitmap data for a predetermined number of bands. , A first page for generating intermediate data for the next page, predicting an intermediate data generation time required to write the generated intermediate data in the first storage means, and comparing the predicted time with a first predetermined value. The predicting means and the intermediate data corresponding to the current page stored in the first storage means are expanded into bitmap data, and the intermediate data are stored in the second storage means. The rendering time required to transfer to the
If the predicted time of the second predicting means for comparing with the predetermined value of the first predicting means or the second predicting means is larger than the first or second predetermined value, In the image forming apparatus, there is provided control means for controlling the intermediate data corresponding to each page to be expanded into bitmap data before starting output to the printer engine.

Another object of the present invention is to interpret the input image information, generate predetermined intermediate data consisting of a plurality of bands, and expand it into printable bit map data, and a bit map data. A method of controlling an image forming apparatus including a printer engine for printing a sheet on a recording material, the printer controller including a first storing step of storing intermediate data in a first storing means, and bitmap data for a predetermined number of bands. In the second storage means, the intermediate data for the next page is generated, and the intermediate data generation time required for writing the generated intermediate data in the first storage step is predicted. The prediction step that compares the prediction time with a predetermined value, and if the prediction time is greater than the predetermined value, the intermediate data for the next page is generated. And a control step of performing control so as to start outputting bitmap data of intermediate data for the current page to the printer engine after the end of the current page.

Another object of the present invention is to interpret the input image information, generate predetermined intermediate data consisting of a plurality of bands, and expand it into printable bitmap data, and a bitmap data. A method for controlling an image forming apparatus including a printer engine that prints on a recording material, the printer controller storing first intermediate data in a first storage unit;
A second storage step of storing a predetermined number of bands of bitmap data in the second storage means, and intermediate data necessary for generating intermediate data for the next page and writing the generated intermediate data in the first storage means. A first prediction step of predicting the data generation time and comparing the predicted time with a first predetermined value, and intermediate data corresponding to the current page stored in the first storage means to bitmap data. Unfold,
A second prediction step of predicting a rendering time required for transfer to the printer engine via the second storage means and comparing the predicted time with a second predetermined value;
If the prediction time of the first prediction step or the second prediction step is larger than the first or second predetermined value, all the intermediate data corresponding to the current page in the first storage unit is expanded into bitmap data. From the printer engine to the printer engine, and a control step of performing control to start output from the printer to the printer engine.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below in detail based on its preferred embodiments with reference to the drawings. In the following embodiments, a laser beam printer will be described as an example of an image forming apparatus, but any image forming apparatus including a band memory may be used as an image forming apparatus including an inkjet printer. Needless to say, is applicable.

<First Embodiment> FIG. 1 is a vertical sectional view showing a structural example of a laser beam printer (LBP) as an example of an image forming apparatus according to an embodiment of the present invention. In the figure, reference numeral 1000 denotes an LBP main body, which receives print information (character codes, etc.), form information, macro commands, etc. supplied from a host computer 3000 (FIG. 2) externally connected via a printer control unit 1001. Then, the corresponding character pattern, form pattern, etc. are created in accordance with the information and commands, and an image is formed on a recording paper or the like as a recording medium.

1012 is a switch for operation and L
An operation panel on which an ED display and the like are arranged, 1001 is L
A printer control unit that controls the entire BP main body 1000 and analyzes print information and the like supplied from a host computer. The printer control unit 1001 analyzes print information, generates intermediate data based on the analysis result, generates bitmap data from the intermediate data, and finally converts the bitmap data into a video signal to output a laser driver. Output to 1002.

The laser driver 1002 is a semiconductor laser 1.
This is a circuit for driving the semiconductor laser 003, and controls the semiconductor laser 1003 to be turned on / off according to the input video signal. Laser light 10 emitted from the semiconductor laser 1003
Reference numeral 04 denotes a rotary polygon mirror 1005 that is reflected in the left-right direction (direction perpendicular to the paper surface) and scans and exposes on an electrostatic drum 1006 that is uniformly charged to a predetermined potential in advance. As a result, an electrostatic latent image corresponding to the video signal is formed on the electrostatic drum 1006.

On the other hand, a cut sheet is used as a recording medium as a recording medium, and the cut sheet recording sheet is stored in a sheet cassette 1008 mounted on the LBP 1000, and a sheet feeding roller 1009, a conveying roller 1010 and a conveying roller 101.
1 is taken into the apparatus and the electrostatic drum 100
6 are supplied to the opposite positions. Then, the electrostatic drum 100
The electrostatic latent image formed on 6 is developed with toner by a developing unit 1007 provided around the electrostatic drum 1006, and then transferred to a recording sheet. The toner image transferred onto the recording paper is fixed on the recording paper by heat and / or pressure by a fixing device.

Further, the LBP main body 1000 is provided with at least one or more card slots (not shown), and in addition to a built-in font, an optional font card, a control card (emulation card) capable of interpreting print information of different languages, etc. are connected. It is configured to be able to.

Next, with reference to the block diagram shown in FIG. 2, description will be given of a configuration relating to print control of the laser beam printer of FIG. 1 and a host computer connected to the laser beam printer. In the figure, reference numeral 3000 denotes a host computer, which includes a computer main body 2000, a keyboard (KB) 9, a CRT 10 and an external memory 11 which are connected to the outside.

The host computer 3000 has a ROM 3
The CPU 1 for executing creation, editing, print processing, etc. of a document in which graphics, images, characters, tables (including spreadsheets, etc.) are mixed based on the document processing program, etc. stored in the program ROM. CPU1 is system bus 4
To control the overall operation of the host computer 3000.

In addition to the program ROM for storing the control program of the CPU 1 and the like, the ROM 3 stores a font ROM for storing font data and the like used in the above document processing, and the above-mentioned document processing and the like. There is also provided a data ROM for storing various data (for example, a fixed pattern, a test print form, etc.) used for the above. Two
Is a RAM and functions as a main memory, a work area, etc. of the CPU 1. 5 is a keyboard controller (KBC)
Then, key input from the keyboard 9 or a pointing device (not shown) is controlled.

Reference numeral 6 is a CRT controller (CRTC),
Controls the display on the CRT display (CRT) 10.
A memory controller (MC) 7 accesses the external memory 11 such as a hard disk (HD) or a floppy (registered trademark) disk (FD) that stores a boot program, various applications, font data, user files, edit files, and the like. To control. Reference numeral 8 denotes a printer controller (PRTC), which is a printer 100 via a predetermined bidirectional interface (interface) 21.
0 to execute communication control processing with the printer 1000. Note that the CPU 1 executes, for example, a process (rasterize) of the outline font to the video RAM set on the RAM 2, and the WY on the CRT 10 is performed.
SIWYG is possible. In addition, the CPU1 is CR
Various registered windows are opened based on commands designated by a mouse cursor (not shown) on T10, and various data processes are executed.

In the printer 1000, a printer CPU 12 includes various devices connected to the system bus 15 based on a control program stored in the program ROM of the ROM 13 or a control program stored in the external memory 14. Access to the printer is comprehensively controlled, and an image signal as output information is output to the printing unit (printer engine) 17 connected via the printing unit interface 16.

The font ROM of the ROM 13 stores font data and the like used when the output information is generated, and the data ROM of the ROM 13 includes the external memory 14 such as a hard disk of the printer 1000. The information and the like used on the host computer in the case of not having The CPU 12 can perform communication processing with the host computer 3000 via the input unit 18, and can notify the host computer 3000 of information and the like in the printer 1000. Reference numeral 19 denotes a RAM that functions as a main memory, a work area, etc. of the CPU 12, and is configured so that the memory capacity can be expanded by an optional RAM connected to an expansion port (not shown). The RAM 19 has an output information expansion area, an environment data storage area, etc., and a part or all of the RAM 19 can be configured by a non-volatile memory (NVRAM). The external memory 14 connected as an option is a hard disk (H
D), IC card, etc., and stores font data, emulation program, form data, etc. Access to the external memory 14 is controlled by the memory controller (MC) 20. An operation panel 1012 is provided with switches for inputting operations and commands of the printer 1000, an LED display, and the like.

The above-mentioned external memory is not limited to one, but at least one external memory is provided, and in addition to the built-in font, an optional font card and a plurality of external memories storing programs for interpreting printer control languages of different languages are connected. It may be configured to be capable. Further, an NVRAM (not shown) may be further included to store printer mode setting information from the operation panel 1012.

(Printing Process) Next, the printing process of the printer according to the first embodiment of the present invention will be described with reference to the functional block diagram shown in FIG. 3 and the flowcharts shown in FIGS. 4 and 5. Of the functional blocks in FIG. 3, the reception buffer 5005 and the page buffer 502 are included.
The 0 and band memory 5040 is realized by the RAM 19 and / or the external memory 14. The remaining blocks except the printer engine 5060 are all CPU1.
2 is realized by executing a program stored in the program ROM and controlling necessary hardware. Similarly, the CPU 12 is the main subject of the processing shown in FIGS. 4 and 5.

In the print processing of this embodiment, the read / write time of the storage device generated by writing the intermediate data of the next page to the page buffer is predicted, and the time for reading the intermediate code of this page from the page buffer, the rendering time, and the band. Predict the time to write and read to the memory, and if the time to write the intermediate data of the next page to the page buffer is longer than the default value, generate the print signal of this page after generating the intermediate data of the next page. It was done.

When command data described in PDL is input from the host computer 3000 (not shown) via the interface 21, the command data is temporarily stored in the reception buffer 5005, and then the command analysis / edit processing unit 5000 analyzes and analyzes the command. Edit (step S10)
00 and S1010). The command-analyzed data is sent to the intermediate data generation unit 5010, and the intermediate data generation unit 5010 generates the intermediate data based on the data (step S1020). The generated intermediate data is stored in the page buffer 5020 (step S103).
0). Then, steps S1010 to S1030 are repeated until one page of command data is processed (step S1040).

When the intermediate data for one page is stored in the page buffer 5020, it is judged whether or not the next page data exists in the reception buffer 5005 (step S1).
050), if there is data for the next page, the rendering processing unit 5030 causes the page buffer 5020
Rendering of the first two bands of the intermediate data stored in is stored in the band memory 5040 (step S1055).

Then, the next page data is read from the reception buffer 5005, the intermediate data generation prediction unit 5080 predicts the generation time of the intermediate data for the next page,
It is determined whether or not the predicted time is longer than a predetermined specified value (step S1060). As a result of the determination, when the predicted generation time of the intermediate data of the next page is longer than the specified value, the process waits until the generation of the intermediate data of the next page is completed (steps S1065 and S1070).

When the generation of the intermediate data of the next page is completed, the print signal instructing unit 5090 outputs the print signal to the engine output control unit 5050 (step S11).
00). In step S1060, when the predicted generation time of the intermediate data of the next page is equal to or less than the specified value, the print signal instructing unit 5090 prints it on the engine output control unit 5050 without waiting for the generation of the intermediate data of the next page. A signal is output (step S1100).

On the other hand, in step S1050, if the data of the next page does not exist, the page buffer 50
The first two bands of the intermediate data stored in 20 are rendered and stored in the band memory (step S
Immediately after 1080), the print signal is transmitted (step S1100).

When the engine output control unit 5050 receives the output instruction signal from the engine 5060 (step S1)
110), the bitmap data of the first two bands stored in the band memory 5040 is output in synchronization with the engine 5060 (step S1120). Subsequently, the rendering processing unit 5030 performs rendering for the third band and subsequent bands, stores it in the band memory 5040 (step S1130), and the engine output control unit 5060 outputs it in synchronization with the engine 5060 (step S1140).
Printing is performed by the engine 5060 while synchronizing with the engine until all intermediate data for one page stored in the page buffer 5020 is processed (step S1150).

When the processing of the intermediate data for one page is completed, it is checked whether or not the data of the next page exists in the page buffer 5020 (step S1160), and if it exists, the process returns to step S1055 to continue the processing. . On the other hand, if there is no data in the page buffer 5020, the process ends.

In order to prevent printer overrun, the rendering processing unit 5030 must render the intermediate data at a processing speed equal to or faster than the processing for outputting the bitmap data from the band memory 5040 to the engine 5060. I won't.

Further, the intermediate data generation prediction unit 5080 calculates the size, complexity, etc. of the intermediate data of the next page to be generated by a predetermined method, and the page buffer 5
Predict the write time to 020. The calculation method is arbitrary, but for example, the processing time and the amount of generated data are made into a table for each command in advance, and the processing time and the amount of generated data are calculated by referring to the table from the command included in the data for one page. Accumulate. Then, the write time to the page buffer 5020 is predicted from this cumulative value. The write time to the page buffer 5020 can be obtained by dividing the expected amount of generated data by the transfer rate obtained by subtracting a predetermined margin from the data transfer rate in the printer assuming an access conflict.

Therefore, the predicted intermediate data generation time in the present invention is a value obtained by combining the predicted intermediate data generation processing time and the predicted transfer (write) time of the generated intermediate data to the page buffer 5020.

In the present invention, it is determined whether or not the intermediate data of the next page can be generated during the rendering of this page, based on whether or not the predicted generation time of the intermediate data is longer than the preset value prepared in advance. It is like this. This default value is a limit value at which it is possible to read the intermediate data from the page buffer 5020 in synchronization with the engine 5060, perform rendering, write to the band memory, and further read the bitmap data from the band memory. If the time for writing the intermediate data of the next page to the page buffer 5020 exceeds this default value and an attempt is made to perform rendering while generating the intermediate data of the next page, the engine 5060
The intermediate data cannot be read from the page buffer 5020, rendered, and written to and read from the band memory in synchronism with the above, and as a result, a print overrun occurs.

(Timing Chart between Controller and Printer Engine) Next, the printing process in this embodiment will be further described with reference to the timing charts shown in FIGS. 6 and 7. FIG. 6 shows that when the predicted generation time of the intermediate data of the next page is smaller than the specified value, that is, during the rendering of the first page (to be exact, as described above, the intermediate data of the first page is read from the page buffer 5020, Timing chart showing the exchange of signals between the controller and engine when it is possible to generate the intermediate data of the second page during rendering, writing to the band memory, and reading the bitmap data from the band memory) Is.

When the intermediate data of the first page is generated,
The prediction process of the intermediate data generation of the second page is performed, and at the same time, the rendering process of the first two bands of the first page is performed. Since the generation time of the intermediate data of the second page is smaller than the specified value, the controller outputs a print signal to the printer engine. Upon receiving the print signal, the printer engine outputs an engine output instruction signal to the controller. The bitmap data for the first page is output in synchronization with the engine output instruction signal, and then the paper for the first page is conveyed. While outputting the bitmap data of the first page, the intermediate data of the second page is generated in parallel.

When the output of the bitmap data of the first page and the generation of the intermediate data of the second page are completed, the prediction process of the intermediate data generation of the third page is performed, and at the same time, the first two bands of the second page are simultaneously processed. The rendering process is performed. Since the generation time of the intermediate data on the third page is smaller than the specified value, the controller outputs a print signal to the printer engine. Upon receiving the print signal, the printer engine outputs an engine output instruction signal to the controller. The bitmap data of the second page is output in synchronization with the engine output instruction signal, and then the second page of paper is conveyed. While outputting the bitmap data of the second page, the intermediate data of the third page is generated in parallel. The same operation is repeated for the third and subsequent pages.

On the other hand, FIG. 7 shows a controller when the predicted generation time of the intermediate data of the next page is longer than the specified value, that is, when the intermediate data of the second page cannot be generated during the rendering of the first page. 6 is a timing chart showing the exchange of signals with the engine. When the intermediate data of the first page is generated, the prediction process of generating the intermediate data of the second page is performed, and at the same time, the rendering process of the first two bands of the first page is performed. Since the generation time of the intermediate data of the second page is longer than the specified value, the print signal is not output and the intermediate data of the second page is generated. Two
When the generation of the intermediate data of the page is completed, the controller outputs a print signal to the printer engine. Upon receiving the print signal, the printer engine outputs an engine output instruction signal to the controller. The bitmap data for the first page is output in synchronization with the engine output instruction signal, and then the paper for the first page is conveyed.

When the output of the bitmap data of the first page is completed, the prediction process of the intermediate data generation of the third page is performed, and at the same time, the rendering process of the first two bands of the second page is performed. Since the generation time of the intermediate data of the third page is longer than the specified value, the intermediate data of the third page is generated. When the generation of the intermediate data of the third page is completed, the controller outputs a print signal to the printer engine. Upon receiving the print signal, the printer engine outputs an engine output instruction signal to the controller. The bitmap data of the second page is output in synchronization with the engine output instruction signal, and then the second page of paper is conveyed. The same operation is repeated for the third and subsequent pages.

In this embodiment, if the total expected time of the intermediate page data generation time of the next page and the write time to the page buffer is larger than the default value, the intermediate page data of the current page is generated after the intermediate page data of this page is generated. The print signal is output. However, the print signal is not limited to this. If the time to write the intermediate data of the next page to the page buffer is longer than the default value, the print signal of this page is output and this page is set to the engine. It is of course possible to generate the intermediate data of the next page after the output to.

<Second Embodiment> FIG. 8 is a block diagram of a second embodiment of the present invention, in which blocks having the same functions as those in the first embodiment are designated by the same reference numerals. is there. As is clear from a comparison between FIG. 8 and FIG. 3, which is a functional block diagram in the first embodiment, the rendering prediction unit 5070 and the AND circuit 50 in the present embodiment.
85 and a bitmap memory 5095 are added.

The present embodiment is characterized in that the print processing is performed in consideration of not only the intermediate data generation time but also the intermediate data rendering time. That is, the time to read the intermediate code of this page from the page buffer by predicting the read / write time of the storage device that occurs when writing the intermediate data of the next page to the page buffer,
Predict the rendering time, the time to write to and read from the band memory, and if the time to write the intermediate data of the next page to the page buffer is longer than the default value, generate the bitmap of this page and then print the print signal of this page. It is designed to be output. Hereinafter, the print processing according to this embodiment will be described with reference to the flowcharts of FIGS. 9, 10, and 11.

When command data described in PDL is input from the host computer 3000 (not shown) via the interface 21, the command data is temporarily stored in the reception buffer 5005, and then the command analysis / edit processing unit 5000 analyzes and analyzes the command. Edit (step S20)
00 and S2010). The command-analyzed data is sent to the intermediate data generation unit 5010, and the intermediate data generation unit 5010 generates intermediate data based on the data (step S2020). The generated intermediate data is stored in the page buffer 5020 (step S203).
0). Then, the above steps S2010 to S2030 are repeated until one page of intermediate data is processed (step S2040).

When the intermediate data for one page is stored in the page buffer 5020, it is determined whether or not the next page data exists in the reception buffer 5005 (step S2).
050), if there is data for the next page, the rendering processing unit 5030 causes the page buffer 5020
Rendering of the first two bands of the intermediate data stored in is stored in the band memory 5040 (step S2055).

Then, the next page data is read from the reception buffer 5005, the intermediate data generation prediction unit 5080 predicts the generation time of the intermediate data for the next page,
It is determined whether the predicted time is longer than a predetermined specified value (step S2060). As a result of the determination, if the predicted generation time of the intermediate data of the next page is equal to or smaller than the specified value, it is further determined whether or not the rendering time of this page is larger than a predetermined value set in advance (step S2062). If the estimated rendering time of this page is equal to or smaller than the specified value, the print signal instruction unit 5
The print signal is output to the engine output control unit 5050 from 090 (step S2100).

On the other hand, in step S2060, if the predicted generation time of the intermediate data of the next page is larger than the specified value, the rendering processing unit 5030 renders the intermediate data of this page, and the bitmap data is stored in the bitmap memory 5095. (Step S2064). Similarly, in step S2062,
If the estimated rendering time of this page is longer than the specified value, the rendering processing unit 5030 renders the intermediate data of this page and stores the bitmap data in the bitmap memory 5095 (step S2064). Renders the intermediate data of this page and stores the bitmap data in the bitmap memory 509.
5 is completed (step S2066), the print signal instructing unit 5090 outputs a print signal to the engine output control unit 5050 (step S2100).

On the other hand, in step S2050, if the data of the next page does not exist, the page buffer 50
The first two bands of the intermediate data stored in 20 are rendered and stored in the band memory (step S
2080).

If it is determined in step S2062 that the estimated rendering time of this page is larger than the predetermined value, the rendering processing unit 5030 renders the intermediate data of this page, and the bitmap data is stored in the bitmap memory 5095. It is stored (step S2064). Renders the intermediate data of this page and stores the bitmap data in the bitmap memory 5
After storing the data in 095 (step S2066), the engine output control unit 505 is controlled by the print signal instruction unit 5090.
A print signal is output to 0 (step S2100).

Turning to FIG. 11, the engine output control unit 50
Upon receiving the output instruction signal from the engine 5060 (step S2110), the 50 outputs the bitmap data of the first two bands stored in the band memory 5040 in synchronization with the engine 5060 (step S212).
0). Subsequently, it is checked whether or not there is data in the bit map memory 5095 (step S2122). If there is data in the bit map memory 5095, the data of the third and subsequent bands are read from the bit map memory 5095 and synchronized with the engine 5060. It is output (step S2124). Printing is performed by the engine 5060 while synchronizing with the engine until all the data stored in the bitmap memory 5095 is read (step S2126).

On the other hand, if there is no data in the bit map memory 5095 in step S2122, the intermediate data of the third band and thereafter is read from the page buffer 5020, rendered, and stored in the band memory 5040 (step S2130). It is output in synchronization with 5060 (step S2140). Printing is performed by the engine 5060 while synchronizing with the engine until all the intermediate data for one page stored in the page buffer 5020 is processed (step S21).
50).

When the processing of the intermediate data for one page is completed, it is checked whether or not the data of the next page exists in the page buffer 5020 (step S2152), and if it exists, the process returns to step S2055 to continue the processing. . On the other hand, if there is no data in the page buffer 5020, the process ends.

In the rendering prediction unit 5070,
Whether it is possible to calculate the size, complexity, etc. of the generated intermediate data of this page, read the intermediate data of this page from the page buffer 5020, and write and read it to the band memory in synchronization with the engine 5060. I am predicting. Specifically, the complexity and the time required for processing are predicted according to the type and number of commands included in the intermediate data, and the write time to the band memory is predicted from the expected amount of generated data. It is determined whether or not the processing synchronized with the engine 5060 is possible based on the total time.

The intermediate data generation prediction unit 5080 calculates the size and complexity of the intermediate data of the next page to be generated, predicts the writing time to the page buffer 5020, and during the rendering of this page, Similar to the first embodiment, it is determined whether the intermediate data of the next page can be generated.

The AND circuit 5085 receives the outputs of the rendering prediction unit 5070 and the intermediate data generation prediction unit 5080 as input, and instructs the print signal instruction unit 5080 when both the intermediate data generation prediction time and the rendering prediction time are equal to or smaller than a predetermined value. Instruct to output the print signal. Also,
In other cases, the rendering processing unit 5030 is instructed to render this page.

Therefore, when it is predicted that the intermediate data of this page cannot be read from the page buffer 5020 and written to and read from the band memory in synchronization with the engine 5060, or during the rendering of this page, If it is predicted that the intermediate data of the next page cannot be generated, after generating the bitmap of this page,
The print signal for this page is output.

The bitmap memory 5095 is composed of a memory and a bus independent of the page buffer 5020. That is, since the bitmap memory 5095 and the page buffer 5020 can read and write at the same time, the page buffer 5020 can be read while the data of this page is being read from the bitmap memory 5095.
Even if the intermediate data of the next page is written in, the process of reading the data of this page from the bitmap memory 5095 does not slow down.

[0061]

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

Another object of the present invention is to supply a storage medium storing a program code of software for realizing the functions of the above-described embodiments to a system or apparatus, and to supply a computer (or CPU) of the system or apparatus.
It is needless to say that it can be achieved by reading and executing the program code stored in the storage medium.

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

A storage medium for supplying the program code is, for example, a floppy disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a CD.
-R, magnetic tape, non-volatile memory card, ROM, etc. can be used.

Further, not only the functions of the above-described embodiment are realized by executing the program code read by the computer, but also the OS (operating system) running on the computer based on the instructions of the program code. It is needless to say that this also includes a case where the above) performs a part or all of the actual processing and the processing realizes the functions of the above-described embodiments.

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

When the present invention is applied to the above-mentioned storage medium, the storage medium has a program code corresponding to the above-described flowchart (shown in at least one of FIGS. 4, 5, and 9 to 11). Will be stored.

[0068]

As described above, according to the image forming apparatus of the present invention, not only the generation time of the intermediate data but also the read / write time of the storage device generated by writing the generated intermediate data in the page buffer are taken into consideration. By performing print control by maintaining the maximum print speed,
It has the effect of preventing print overrun.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration example of a laser beam printer as an embodiment of an image forming apparatus of the present invention.

FIG. 2 is a block diagram illustrating a connection relationship between the printer shown in FIG. 1 and its host computer and a configuration related to print processing.

FIG. 3 is a functional block diagram illustrating a configuration related to print processing in the printer shown in FIG.

FIG. 4 is a flowchart illustrating a printing process according to the first embodiment.

FIG. 5 is a flowchart illustrating print processing according to the first embodiment.

FIG. 6 is a timing chart of print processing according to the first embodiment.

FIG. 7 is a timing chart of print processing according to the first embodiment.

FIG. 8 is a functional block diagram illustrating a configuration related to print processing of the image forming apparatus according to the second embodiment.

FIG. 9 is a flowchart illustrating a printing process according to the second embodiment.

FIG. 10 is a flowchart illustrating a printing process according to the second embodiment.

FIG. 11 is a flowchart illustrating a printing process according to the second embodiment.

[Explanation of symbols]

1 CPU 2 RAM 3 ROM 4 system bus 12 CPU 13 ROM 19 RAM 3000 host computer 1000 printers 5000 Command analysis edit processing unit 5005 Receive buffer 5010 Intermediate data generation unit 5020 page buffer 5030 Rendering processing unit 5040 band memory 5050 Engine output control unit 5060 printer engine 5070 Rendering prediction unit 5080 Intermediate data generation prediction unit 5085 AND circuit 5090 Print signal instruction unit 5095 Bitmap memory

Claims (12)

[Claims] 1. A printer controller that interprets input image information, generates predetermined intermediate data composed of a plurality of bands, and expands the printable bitmap data, and a printer that prints the bitmap data on a recording material. An image forming apparatus including an engine, wherein the printer controller includes a first storage unit that stores the intermediate data, a second storage unit that stores the bitmap data for a predetermined number of bands, and a next page. Predicting means for generating the intermediate data, predicting an intermediate data generation time required to write the generated intermediate data in the first storage means, and comparing the predicted time with a predetermined value; Is larger than the predetermined value, the intermediate data bit for the current page is not generated after the intermediate data for the next page is generated. Image forming apparatus characterized by a control means for controlling to start the output to the printer engine of the map data. 2. The printer engine processing for generating the printable bitmap data from the intermediate data stored in the first storage means and transferring the printable bitmap data to the printer engine. The image forming apparatus according to claim 1, wherein the image forming apparatus has a value that represents a maximum time allowed to be executed in synchronization with the operation of. 3. When the predicted time is equal to or smaller than the predetermined value, the control means generates the intermediate data for the next page and writes the generated intermediate data in the first storage means, 3. The expansion processing of the intermediate data corresponding to the current page stored in the first storage unit into the bitmap data is controlled so as to be processed in parallel. The image forming apparatus described. 4. A printer controller that interprets input image information, generates predetermined intermediate data composed of a plurality of bands, and expands the printable bitmap data, and a printer that prints the bitmap data on a recording material. An image forming apparatus including an engine, wherein the printer controller includes a first storage unit that stores the intermediate data, a second storage unit that stores the bitmap data for a predetermined number of bands, and a next page. Of the intermediate data, predicting an intermediate data generation time required to write the generated intermediate data in the first storage means, and comparing the predicted time with a first predetermined value. And expanding the intermediate data corresponding to the current page stored in the first storage means into bitmap data,
Second prediction means for predicting a rendering time required for transfer to the printer engine via the second storage means, and comparing the predicted time with a second predetermined value; and the first prediction. Means or the second prediction means has a predicted time longer than the first or second predetermined value, all intermediate data corresponding to the current page in the first storage means are expanded into bitmap data. An image forming apparatus comprising: a control unit that performs control so as to start output to the printer engine after that. 5. The first and second predetermined values are the first
The maximum time allowed for executing the process of generating printable bitmap data from the intermediate data stored in the storage means and transferring the printable bitmap data to the printer engine in synchronization with the operation of the printer engine. The image forming apparatus according to claim 4, wherein the image forming apparatus has a value represented. 6. When the prediction time by the first and second prediction means is equal to or smaller than the first and second predetermined values,
The control means generates the intermediate data for the next page, writes the generated intermediate data into the first storage means, and stores the intermediate data corresponding to the current page stored in the first storage means. The image forming apparatus according to claim 4, wherein the image forming apparatus is controlled so that the expansion processing to the bitmap data is processed in parallel. 7. A printer controller that interprets input image information, generates predetermined intermediate data composed of a plurality of bands, and expands the printable bitmap data, and a printer that prints the bitmap data on a recording material. A method of controlling an image forming apparatus including an engine, wherein in the printer controller, a first storage step of storing the intermediate data in a first storage means; A second storage step of storing in the storage means, generation of the intermediate data for the next page, prediction of the intermediate data generation time required to write the generated intermediate data in the first storage step, and the estimated time And a prediction step of comparing a predetermined value with a predetermined value, and if the prediction time is larger than the predetermined value, the intermediate data for the next page is Method of controlling an image forming apparatus characterized by having a data generation is completed, and a control step of performing control so as to activate the output to the printer engine of the bitmap data of said intermediate data for the current page. 8. The printer engine processing for generating the printable bitmap data from the intermediate data stored in the first storage means and transferring the printable bitmap data to the printer engine is performed by the printer engine. 8. The control method of the image forming apparatus according to claim 7, wherein the control value is a value that represents a maximum time allowed to be executed in synchronization with the operation of. 9. If the predicted time is equal to or smaller than the predetermined value, the control step includes generating the intermediate data for the next page and writing the generated intermediate data into the first storage means. 9. The expansion processing of the intermediate data corresponding to the current page stored in the first storage means into the bitmap data is controlled so as to be processed in parallel. A method for controlling an image forming apparatus as described. 10. A printer controller which interprets input image information, generates predetermined intermediate data composed of a plurality of bands, and expands it into printable bitmap data,
A method of controlling an image forming apparatus including a printer engine for printing the bitmap data on a recording material, the printer controller storing a first storage step of storing the intermediate data in a first storage means, and a predetermined band. A second storage step of storing a few minutes of the bitmap data in the second storage means, and generation of the intermediate data of the next page, and writing the generated intermediate data in the first storage means. A first prediction step of predicting the intermediate data generation time and comparing the predicted time with a first predetermined value; and biting the intermediate data corresponding to the current page stored in the first storage means. Expand to map data,
A second prediction step of predicting a rendering time required for transfer to the printer engine via the second storage means and comparing the predicted time with a second predetermined value; and the first prediction. When the prediction time of the step or the second prediction step is larger than the first or second predetermined value, all the intermediate data corresponding to the current page in the first storage means are expanded into bitmap data. And a control step for performing control so as to start output to the printer engine after that. 11. The process until the first and second predetermined values generate printable bitmap data from the intermediate data stored in the first storage means and transfer it to the printer engine, 11. The method of controlling an image forming apparatus according to claim 10, wherein the value is a value that represents a maximum time allowed for execution in synchronization with the operation of the printer engine. 12. If the prediction time by the first and second prediction steps is equal to or smaller than the first and second predetermined values, the control step generates the intermediate data for the next page and the generated intermediate data. The writing of data into the first storage step and the expansion processing of the intermediate data corresponding to the current page stored in the first storage means into the bitmap data are controlled in parallel. 11. The method according to claim 10, wherein
Alternatively, the image forming apparatus control method according to claim 11.