JP2003335001A - Printing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a function that sequentially selects a method for controlling a band by a compression method making use of its advantage, thereby enabling a rapid procedure to control the band. <P>SOLUTION: The printing apparatus is provided with a means for inputting an image data by a page description language, a means for translating the page description language into an expression for coding a band, a means for translating the above expression for coding the band, a means for rasterising and generating a raster data from the above band coding expression and a first storage means of storing the above raster data, a second storage means of storing the raster data after compression, a means for selecting the compression means from a plurality of the compression means to be used and a plurality of band controlling means that control the above compression means. <P>COPYRIGHT: (C)2004,JPO

Description

Description: BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to an image forming apparatus for performing drawing with a rasterizing function for each band. [0002] Conventionally, laser beam printers and the like,
In an image forming apparatus called a page printer, one page of raster data is held in a raster memory to form an image. Raster data as such an image processing device handles not only text but also all kinds of images from simple figures to images such as photographs. In recent years, the resolution of these image forming apparatuses has been improved. For example, a resolution of 600 dpi requires as much as 4 Mbytes of memory to create one A4 size page. Even now, the resolution tends to increase further, and the gray scale conventionally expressed by 2 gray scales (1 bit) per pixel is changed from 16 gray scales (4 bits) to 256 gray scales (8 bits). Increasingly, they require an increasingly large amount of raster memory. In recent years, the number of colors has been increased, and in the case of a YMCK space compared to monochrome, the memory size required for four planes has been further increased. [0004] In order to suppress an increase in cost due to such an increase in memory, various memory saving techniques have been proposed. For example, there is a method in which one page of raster data is not stored in the raster memory, but one page is divided into a plurality of bands, and the raster data is compressed and stored in the raster memory. And as mentioned above, as the amount of data increases,
In terms of memory size, the effect of data compression is also increasing. [0005] However, the above 1)
In the case of processing that divides a page into a plurality of bands, if a compression method that uses the dependency between bands is used when compressing the bands, be sure to start from the first band of the page to the last band. It is necessary to perform compression control sequentially up to the band. When raster data does not exist in a band, it is not necessary to perform raster data generation and compression processing, but compression processing must be performed in order to obtain a dependency between bands. Further, when the compression method is changed to another compression method, it is necessary to use a control method using the dependence between bands even if the compression method does not require the dependence between bands.
Then, even when raster data does not exist, it is necessary to perform compression processing, and there is a problem that an additional processing time is required. Accordingly, the present invention provides an image data input means using a page description language, a means for translating the page description language into a band-encoded expression, and a method for converting raster data from the band-encoded expression. A rasterizing unit for generating the raster data, a first storage unit for storing the raster data, a plurality of compression units for compressing the raster data, a second storage unit for storing the raster data after compression,
In a printing apparatus having a compression selecting unit that selects a compression unit to be used from the plurality of compression units and a plurality of band control units that control the compression unit, the band control unit is switched according to a selection result of the compression selection unit. The above problem is solved by controlling the compression of the band. FIG. 1 is a cross-sectional view showing the internal structure of a laser beam printer (hereinafter abbreviated as LBP) used in the present embodiment. The LBP is a character from a data source (not shown). Registration of patterns and registration of fixed forms (form data) can be performed. In the figure, reference numeral 1000 denotes an LBP main unit, which is character information (character code) supplied from an externally connected host computer (2001 in FIG. 2).
And form information or macro instructions are input and stored, and a corresponding character pattern or form pattern is created according to the information, and an image is formed on recording paper as a recording medium. Reference numeral 1012 denotes an operation panel on which switches for operation, an LED display, and the like are arranged. Reference numeral 1001 denotes a printer control unit that controls the entire LBP 1000 and analyzes character information supplied from a host computer. This control unit 1001
Mainly converts character information into a video signal of a corresponding character pattern and outputs the video signal to the laser driver 1002. The laser driver 1002 is a circuit for driving the semiconductor laser 1003, and switches on and off a laser beam 1004 emitted from the semiconductor laser 1003 according to an input video signal. Laser 1004 is a rotating polygon mirror 100
5 and scans on the electrostatic drum 1006 while being swung right and left. As a result, an electrostatic latent image of a character pattern is formed on the electrostatic drum 1006. This latent image is stored in the electrostatic drum 1
After the image is developed by the developing unit 1007 around the sheet 006, the image is transferred to a recording sheet. A cut sheet is used as the recording paper, and the cut sheet recording paper is stored in a paper cassette 1008 mounted on the LBP 1000,
9 and transport rollers 1010 and 1011, and are taken into the apparatus and supplied to the electrostatic drum 1006. FIG. 2 shows an external device 2001 such as a host computer, 2002 shows the entire printer controller unit, 2003 shows an address data bus, and 2 shows an address data bus.
004, a host I / F including a buffer unit; 2005, a CPU for controlling a printer controller unit; 2006, a ROM unit storing a program for performing controller control and the like; 2007, a DMA controlled by the CPU
2008, a panel unit; 2009, a liver circuit unit including an output buffer unit for storing data to be sent to the 2011 engine; and 2010, a RAM unit. First, the page generation in step 300 will be described with reference to the flowchart in FIG. In step 301, image data is input from an external device such as the host computer in FIG. 2001 to the host I / F unit in FIG. 2004 in PDL (page description language). Next, in step 302, step 3
01 is analyzed to create a band-encoded representation. The term "band coded expression" used here refers to drawing objects such as "bitmaps", "run lengths", "trapezoids", "boxes", and "high-speed boundary coded bitmaps" divided into bands and backgrounds. It is a general term for patterns and drawing logic when drawing them in a raster memory. The details of the band coding expression are disclosed in Japanese Patent Application Laid-Open No. 6-8725l. Next, in step 303, a compressed page is generated. The detailed description of the generation of the compressed page will be made using the flowchart of FIG. First, in step 401, a compression method is selected and determined. Detailed description of the selection and determination of the compression method will be made using the flowchart of FIG. First, in step 501, the gradation of the page data in the band coding expression created in step 302 of FIG. 3 is examined. However, in the case of this embodiment, it is assumed that data can be created in two gradations, 1 bit / pixel or 2 bit / pixel. Next, in step 502, the data gradation examined in step 501 is 1 bit / pixel or 2 bit / pixel.
Check for l. If the data gradation is 1 bit / pixel
If so, the process proceeds to step 503. Conversely, data gradation is 2bi
If t / pixel, the process proceeds to step 504. First, if the data gradation is 1 bit / pixel, step 50
In step 3, "compression method 1" is selected as the compression method used on this page. Conversely, when the data gradation is 2 bits /
In the case of pixel, in step 504, “compression method 2” is selected as the compression method used for this page. Next, in step 505, in steps 503 and 504, the compression method selected in each step is stored in the RAM 2010 in FIG. Next, the process proceeds to step 506, where the processing system for selecting and determining the compression method in step 500 is terminated, and the process returns to step 401 in FIG. Next, the process proceeds to step 402 in FIG. 4 to select and determine a band control method. Detailed description of band control method selection / determination will be made using the flowchart of FIG. First, in step 601, the compression method set in step 505 in FIG.
Read from M. Next, in step 602, the compression method read in step 601 is examined. If the read compression method is "compression method 1", the flow advances to step 603 to select "band control method 1" as the band control method. Conversely, if the read compression method is “compression method 2”, the flow advances to step 604 to select “band control method 2” as the band control method. Next, in step 605, in step 603 and step 604, in order to store the compression method selected in each step,
It is stored in the RAM 2010 of FIG. However, it is assumed that this area is different from the area of the RAM used in step 50S of FIG. Next, proceeding to step 606, the processing system for selecting and determining the band control method in step 600 is terminated.
Returning to step 402 of FIG. Next, the process proceeds to step 403 in FIG. 4 to perform processing for generating a compressed band. The detailed description of the generation of the compression band will be made using the flowchart of FIG. First, in step 701, the band control method set in step 605 in FIG.
From the RAM. Next, in step 702,
The band control method read in step 701 is investigated. The read band control method is "band control method 1"
If so, the process proceeds to step 703, and the process of the band control method 1 is performed. The band control method 1 will be described in detail with reference to the flowchart of FIG. First, in step 801, N indicating a band number is initialized to N = 0. Here, N is an integer value and satisfies 0 <= N <= N-MAX. N_MAX is an integer value satisfying 0 <= N_MAX. Next, at step 802, it is checked whether or not the band number N satisfies N <= N_MAX. If N> N_MAX, it indicates that the processing has been completed for all bands, and step 807
To end the processing system of the band control method 1 in step 800. Conversely, if N <= N_MAX, step 80
Proceed to 3. In step 803, step 3 in FIG.
Rendering is performed based on the band coded expression created in step 02. Here, rendering refers to the RA of 2010 in FIG.
A general term for acquiring a memory area for one band included in M, converting the band-encoded representation created in step 302 of FIG. Next, the process proceeds to step 804, where the compression method 1
, The result of rendering in step 803 is compressed, and the compressed band included in the RAM 2010 in FIG. 2 is stored in a page memory for storing one page. It is assumed that the page memory is allocated in advance and is a different area from the memory area for the rendering storage. The “compression method 1” here is
It is assumed that the compression method requires information in the N band when compressing the N + 1 band after compressing the N band, and any compression method that satisfies the above condition may be used. Next, the process proceeds to step 80S, where information for reducing the compression information of the N band to the compression of the N + 1 band is stored in the memory area in the RAM 2010 of FIG. Next, the process proceeds to step 806, where the band number N is set to the next band number N +
Update to 1. The process returns to step 802 again and repeats the processing of step 803 and subsequent steps. When the processing of all the bands is completed, the process proceeds to step 807, and step 7 in FIG.
Return to 03. Conversely, if the band control method read out in step 701 is "band control method 2", the flow advances to step 704 to perform the processing of band control method 2. Band control method 2
Will be described in detail with reference to the flowchart of FIG. First, at step 901, N indicating a band number is initialized to N = 0. Here, N is an integer value and satisfies 0 <= N <= N_MAX. N_MAX is an integer value satisfying 0 <= N_MAX. Next, at step 902, it is checked whether or not the band number N satisfies N <= N MAX. If N> N_MAX, it indicates that the processing has been completed for all the bands, and
To end the processing system of the band control method 2 in step 900. Conversely, if N <= N_MAX, step 90
Proceed to 3. In step 903, it is checked whether drawing information exists in the N band. Here, the drawing information indicates the band coded expression created in step 302 of FIG. If there is no drawing information, the process proceeds to step 906. Conversely, if there is drawing information, the process proceeds to step 904. Next, in step 904, rendering is performed based on the band coded expression created in step 302 of FIG. Here, rendering refers to 2010 in FIG.
Is a general term for acquiring a memory area for one band included in the RAM, and converting the band-encoded expression created in step 302 of FIG. Next, the process proceeds to step 905, in which the result rendered in step 903 is compressed using the compression method 2, and the compressed band included in the RAM 2010 in FIG. 2 is stored in a page memory for storing one page. . It is assumed that the page memory is allocated in advance and is a different area from the memory area for the rendering storage. "Compression method 2" here
"Compression method 1" is different from "compression method 1" in that it is a compression method that can be independently compressed in band units, and any compression method that satisfies the above conditions may be used.
Next, the process proceeds to step 906, where the band number N is updated to the next band number N + 1. Then, the process returns to step 902 again, and repeats the processing of step 903 and subsequent steps. When the processing for all the bands is completed, the process proceeds to step 907 and returns to step 704 in FIG. Next, returning to the flowchart of FIG. 7, when the processing of step 703 or step 704 is completed, the processing proceeds to step 705, where the processing system for generating the compressed band of step 700 is terminated, and the processing returns to step 403 of FIG. . Next, returning to the flowchart of FIG. 4, when the processing of step 403 is completed, the processing proceeds to step 404, the processing system for generating the compressed page in step 400 ends, and the processing returns to step 303 of FIG. Next, returning to the flowchart of FIG. 3, when the process of step 303 is completed, the process proceeds to step 304. Next, at step 304 in FIG. 3, a printing process is performed. The printing process will be described with reference to the flowchart of FIG. First, in step 1001, N indicating a band number is initialized to N = 0. However, N is an integer value and satisfies 0 <= N <= N_MAX. N_MAX is an integer value satisfying 0 <= N_MAX. Next, in step 1002, it is checked whether or not the band number N satisfies N <= N_MAX. If N> N_MAX, it indicates that the processing has been completed for all the bands, and step 100
Proceeding to S8, the processing system of the printing process in step 1000 is ended. Conversely, if N <= N_MAX, step 10
Go to 03. In step 1003, it is checked whether or not the Nth compressed band exists among the compressed bands generated in step 403 in FIG. If there is a compression band, the flow advances to step 1004 to perform decompression processing and store the decompressed data in a memory area of the same size as one band in the RAM 2010 in FIG. Conversely, if there is no compressed band, it is determined that there is no data in the band, the process proceeds to step 100S, and white band data is output.
The self data is stored in a memory area of the same size as one band in the RAM. Next, the process proceeds to step 1006, where Sh
Perform an ipping process. Shipping here
The process is a general term for a process of converting the band data stored in step 1004 or 100S into a video signal and transferring the video signal to the engine 2011 in FIG. Next, the routine proceeds to step 1007, where the band number N is updated to the next band number N + 1. Then, the process returns to step 1002 again, and performs the processing from step 1003 onward until all the bands are completed. When all the bands are completed, the process proceeds to step 1008, the print processing system of step 1000 is terminated, and the process of FIG. 30
Return to 4. Next, the process proceeds to step 305 in FIG. 3, and the processing system for page generation in step 300 is ended. (Other Embodiment 1)
Although the case where the band is temporarily stored in the memory area after the decompression processing is dealt with, the case where the band is directly expanded without being stored in the memory area while being decompressed may be used. (Other Embodiment 2) In the above embodiment,
In the case where there is no drawing information, the case where the rendering is not performed is dealt with, but the rendering may be performed. (Other Embodiment 3) In the above embodiment, the case where a band is coded is dealt with. However, the case where a band other than a band is coded may be used. (Other Embodiment 4) In the above embodiment, the case where a single compression method is selected when the compression processing is selected is dealt with. However, even when the compression processing is selected from a plurality of compression methods. I do not care. (Other Embodiment 5) In the above embodiment, the method of selecting a compression method according to the data gradation is used, but information other than gradation (for example, color information) may be used. (Embodiment 6) In the above embodiment, the case where one type of band control method exists in combination with the compression method has been described. May be present. As described above, means for inputting image data in a page description language, means for translating the page description language into a band coded expression, and generating raster data from the band coded expression. Rasterizing means, first storing means for storing the raster data, a plurality of compressing means for compressing the raster data, second storing means for storing the raster data after compression, and use from the plurality of compressing means In a printing apparatus having compression selection means for selecting a compression means to be performed, and a plurality of band control means for controlling the compression means, according to a selection result of the compression selection means,
By switching the band control means, high-speed processing can be performed while utilizing the characteristics of the compression method.

[Brief description of the drawings] FIG. 1 is a sectional view showing the internal structure of a printing apparatus. FIG. 2 is a block diagram of a printing apparatus. FIG. 3 is a flowchart showing a processing flow. FIG. 4 is a flowchart showing a processing flow. FIG. 5 is a flowchart showing a processing flow. FIG. 6 is a flowchart showing a processing flow. FIG. 7 is a flowchart showing a processing flow. FIG. 8 is a flowchart showing a processing flow. FIG. 9 is a flowchart showing the flow of processing. FIG. 10 is a flowchart showing a processing flow. [Explanation of symbols] 1000 LBP body 1001 Printer control unit 1002 laser driver 1003 Semiconductor laser 1004 laser light 1005 rotating polygon mirror 1006 Electrostatic drum 1007 Development unit 1008 Paper cassette 1009 Paper feed roller 1010 Transport roller the driver 2001 External device 2002 Printer controller 2003 address / data bus 2004 Host I / F 2005 Printer controller control CPU 2006 ROM section 2007 DMA unit 2008 Panel 2009 I / F circuit section 2010 RAM section 2011 Engine conductor laser

Claims (1)

Claims: 1. An image data input unit using a page description language, a unit for translating the page description language into a band coded expression, and a rasterizing unit for generating raster data from the band coded expression. A first storage unit for storing the raster data; a plurality of compression units for compressing the raster data; a second storage unit for storing the raster data after being compressed; and a compression unit used from the plurality of compression units. And a plurality of band control means for controlling the compression means, wherein the band control means is switched according to the selection result of the compression selection means to control the compression of the band. Printing device.