JP2006248184A - Printing apparatus and control method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique for reducing the amount of memory used for color printing and performing higher-speed printing with simpler processing.
A drawing device 105 draws an image for each color to be used at the time of printing for each band, and a compressor 109 outputs a second color other than the first color to be used first when printing each band. The image drawn for the color is compressed immediately after drawing. When printing is performed based on the image drawn for the first color and printing is performed based on the image drawn for the second color, this image is decoded by the decompressor 110 immediately before printing. .
[Selection] Figure 1

Description

  The present invention relates to a printing technique.

  Conventionally, when an image from a host computer is generated and printed by a 4-drum electrophotographic page printer or the like, the input print data is 4 in cyan, magenta, yellow, and black (that is, C, M, Y, K). At least one page of the processing list that is the display list for each color and the object data that is the data rendered by the processing list are generated for each color, and a bitmap image of each color is generated from the object data by the generated processing list. Occurs and draws on memory.

  By scanning this in a printing process and developing it with toner or the like, a final image can be obtained on the printing paper. In the case of a 4-drum electrophotographic page printer, it is necessary to generate images of each color at the same time. Usually, at least one page of image data generated by drawing is stored and stored in a memory or other storage means. A method of printing image data on the means is used. As another method, there is a method in which partial image data is appropriately generated and printed in synchronization with the progress of the printing process of the printing apparatus. Here, the method of storing in the memory is called a spool method, and the method of generating partial images as appropriate is called a banding method.

  However, the above conventional example has the following problems.

  First, in the spool method, printing cannot be started unless the generation of at least one page of image data is completed, and there is a problem that it takes time for first printing. Therefore, a large amount of memory capacity is required. In the case of a color printer, there is a problem that a large amount of memory is required because multi-value data is required for four colors.

  On the other hand, in the banding method, partial images are appropriately generated in synchronization with the progress of the printing process of the print engine. Therefore, the image memory can have at least two partial images. In the electrophotographic printer of the drum, there is a time lag in the execution of the printing process for each color, and the generation time for each color of the partial image is sequentially delayed. It is necessary to generate partial images at different positions simultaneously with respect to time.

  In addition, there is a problem in that the progress of the process of each color is caused across the normal pages and the drawing control becomes complicated. There is also a problem that a drawing processing list and drawing object data need to be held for a long time due to a shift in drawing time, which eventually requires a memory.

  The present invention has been made in view of the above problems, and provides a technique for reducing the amount of memory used for color printing and performing faster printing with simpler processing. For the purpose.

  In order to achieve the object of the present invention, for example, a printing apparatus of the present invention comprises the following arrangement.

A receiving means for receiving print data;
Drawing means for drawing an image based on the print data for each band;
Printing means for performing printing based on the image drawn by the drawing means,
The drawing means includes
For each band, a color image drawing means for drawing an image for each color used at the time of printing,
Compression means for compressing the image drawn by the color image drawing means for the second color other than the first color used first when printing each band, immediately after the drawing,
The printing means includes
First printing means for performing printing based on an image drawn by the color image drawing means for the first color;
When performing printing based on the image drawn by the color image drawing means for the second color, decoding means for decoding the image immediately before that,
And a second printing unit for printing the image decoded by the decoding unit.

  Note that a multi-function peripheral including the printing apparatus having the above configuration is also within the scope of the present invention.

  In order to achieve the object of the present invention, for example, a printing apparatus control method of the present invention comprises the following arrangement.

A receiving process for receiving print data;
A drawing step of drawing an image based on the print data for each band;
A printing step for performing printing based on the image drawn in the drawing step,
The drawing step includes
For each band, a color image drawing process for drawing an image for each color used during printing,
A compression step of compressing the image drawn in the color image drawing step for the second color other than the first color used at the time of printing each band immediately after the drawing,
The printing process includes
A first printing step for performing printing based on the image drawn in the color image drawing step for the first color;
When performing printing based on the image drawn in the color image drawing step for the second color, a decoding step for decoding the image immediately before that,
And a second printing step for printing the image decoded in the decoding step.

  According to the configuration of the present invention, the amount of memory used for color printing can be reduced, and higher-speed printing can be performed with simpler processing.

  Hereinafter, the present invention will be described in detail according to preferred embodiments with reference to the accompanying drawings.

[First Embodiment]
<About the configuration and basic operation of the printing device>
FIG. 1 is a block diagram illustrating a hardware configuration of a printing apparatus according to the present embodiment. In the figure, 101 is a CPU, 102 is a main memory, 103 is a memory controller, 104 is an interface, 105 is a drawing device, 106 is an interrupt controller, 107 is an image memory, 108 is a memory controller, 109 is a compressor, and 110 is decompressed. , 111 is an engine interface, 112 is a print engine, and 113 is an IO port.

  First, the basic printing operation of the printing apparatus according to the present embodiment will be described with reference to FIG. First, a print instruction and print data are sent from a host computer (not shown) via the interface 104. The print data is stored in a predetermined area on the main memory 102 by the memory controller 103 from the interface 104.

  When the print data for at least one page is stored in the main memory 102, the print data is interpreted by the CPU 101, and a processing list that is a drawing display list and a drawing object (object data) are displayed on the main memory 102 as partial pages. That is, it is divided into printing bands.

  When a sufficient processing list and object data are generated on the main memory 102, the CPU 101 outputs an activation signal to the drawing device 105 via the IO port 113 so as to perform a drawing operation in units of print bands.

  Upon receiving this signal, the drawing apparatus 105 reads out the processing list and object data on the main memory 102 via the memory controller 103, and a band image (one band image) on the image memory 107 via the memory controller 108. Draw and form. When the designated drawing is completed, the drawing apparatus 105 outputs a drawing end interrupt signal to the interrupt controller 106, so that the interrupt controller 106 notifies the CPU 101 of the end of processing.

  In addition, the CPU 101 instructs the compressor 109 via the IO port 113 to compress the band image formed on the image memory 107. Upon receiving this instruction, the compressor 109 reads the designated image data via the memory controller 108, compresses it with a predetermined compression method, and forms a compressed image in another area of the image memory 107.

  When the compression of the designated image for one band is completed, the compressor 109 outputs a compression end interrupt signal to the interrupt controller 106, so that the interrupt controller 106 notifies the CPU 101 of the end of processing.

  Further, the CPU 101 instructs the decompressor 110 via the IO port 113 to decompress the compressed band image formed on the image memory 107. The decompressor 110 reads the designated compressed image data via the memory controller 108, decompresses it with a predetermined decompression method, and restores the decompressed image to another area of the image memory 107.

  When the decompression of the designated image for one band is completed, the decompressor 110 outputs a decompression end interrupt signal to the interrupt controller 106, so that the interrupt controller 106 notifies the CPU 101 of the end of processing.

  In addition, the CPU 101 instructs the engine interface 111 via the IO port 113 to perform printing operations for C, M, Y, and K colors independently. The engine interface 111 reads out the designated band image on the image memory 107 via the memory controller 108, converts it into a video signal and outputs it to the print engine 112, so that the print engine 112 performs print processing according to this video signal. Do.

  When printing for the designated band is completed, C, M, Y, and K print end interrupt signals are output to the interrupt controller 106, respectively, and the interrupt controller 106 notifies the CPU 101 of the end of band image printing.

  Note that the CPU 101 can input the vertical synchronization signal, which is the print start timing of each of C, M, Y, and K, from the print engine 112 via the IO port 113 and can know the print timing of each color.

  FIG. 2 is a diagram showing the flow of image drawing processing based on print data. 201 is a drawing processing list, 202 is a bit field configuration of the drawing processing list, 203 is a drawing object, and 204 and 205 are header portions of the drawing object. , Bit data configuration, 206 is a mask data generator, 207 is a color generator, and 208 is a logical operation unit. In the figure, the same parts as those in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted.

  The drawing processing list 201 configured on the main memory 102 is configured as a chain of processing commands. One processing command is designated by 202 as drawing logic, command, drawing coordinates, mask object designation, color object designation, The drawing apparatus 105 forms an image according to this processing command.

  The object data 203 is configured on the main memory 102 as with the processing command, and the mask object is configured with a header portion and a body portion. In the figure, the mask object is the character A of the compressed font, and the data constituting A is stored in the body portion. The header portion 204 of the mask object indicates the type (that is, the compressed font object) and the head address where the body is stored. The mask generator 206 refers to this header portion and generates an image of the character A from the body data stored at the address specified by the head address.

  On the other hand, a color object is designated as a header indicated by 205, and the type is a color object. Similarly, the head address of the body data and the head addresses of the Y, M, C, and K planes of the print color Offset information (plane offset) is stored. As body data, density data of each print color plane is stored. The color generator 207 refers to this object header and generates density data for each plane.

  The mask image generated by the mask generator 206 and the density data generated by the color generator 207 are the original image data at the location specified by the drawing coordinates, and the drawing logic specified by the processing command in the logic operation circuit 208. That is, an image is formed by writing in a position specified by drawing coordinates, which is calculated by logic such as OR, AND, XOR, NOT, and the like. In general, in the drawing logic, density data is often clipped with mask data and written as an OR with the original image. In general, pattern data is also generated in addition to mask data and color data, and logical operation is generally performed. However, since this is not the essence of the present embodiment, two objects are used for clarity of explanation. It has been described as a configuration for drawing with data. The drawing device 105 forms an image on the image memory 107 as described above.

  FIG. 3 is a diagram for explaining the printing operation performed by the printing apparatus having the above configuration in time series, 301 is a drawing operation, and 302, 303, 304, and 305 are printing operations of printing colors C, M, Y, and K, respectively. Expressed in band units. As shown in the figure, the same band is drawn in the order of printing, C, M, Y, K. The data of the C plane is printed directly from the image memory, and the data of M, Y, K is Compress as it is. The compressed data is expanded and used at the printing timing of each color. In this way, all colors are drawn in synchronization with the printing process of the most preceding C plane, and the plane with the delay is compressed on the spot, and is expanded and printed at the time of printing.

<Details of printing operation>
Next, a printing process performed by a printing apparatus having the above configuration will be described in detail. FIG. 4 is a flowchart of processing for receiving print data, rendering an image based on the print data, and compressing the image.

  First, since print data is transmitted from an external device via the interface 104, the CPU 101 stores this print data in a predetermined area on the main memory 102 by the memory controller 103 from the interface 104 (step S1).

  When one page of print data is received, the process proceeds to step S3 via step S2. The CPU 101 interprets the print data, and stores the process list and drawing objects (object data) on the main memory 102 for each band. (Step S3). Next, the value held by the variable n is initialized to 1 (step S4).

  Next, the CPU 101 outputs an activation signal to the drawing device 105 via the IO port 113 in order to draw an image of the n-th band C plane (step S5). As a result, the drawing apparatus 105 starts drawing processing of the C plane image. The C plane image is drawn on the image memory 107. When the drawing of the C-plane image is completed, the drawing apparatus 105 outputs a drawing end interrupt signal to the interrupt controller 106, so that the interrupt controller 106 notifies the CPU 101 of the end of processing.

  Accordingly, when the CPU 101 receives this end notification, the process proceeds to step S7 via step S6, and determines whether or not the value held by the variable n is 1 (step S7). If n = 1, the process proceeds to step S8. On the other hand, if n = 1 is not satisfied, the process proceeds to step S17, and waits until the compression operation of the previous band, that is, the (n-1) th band K-plane is completed (step S17). When the notification of the completion of the compression operation for the K plane is received from the compressor 109, the process proceeds to step S8.

  Next, the CPU 101 outputs an activation signal to the drawing device 105 via the IO port 113 in order to draw an image of the n-th M-plane (step S8). As a result, the drawing apparatus 105 starts drawing processing of the M-plane image. The M-plane image is drawn on the image memory 107. When the drawing of the M-plane image is completed, the drawing apparatus 105 outputs a drawing end interrupt signal to the interrupt controller 106, so the interrupt controller 106 notifies the CPU 101 of the end of processing.

  Therefore, when the CPU 101 receives this end notification, the process proceeds to step S10 via step S9, and the CPU 101 connects the IO port 113 to the compressor 109 in order to compress the M-plane image drawn by the drawing device 105. (Step S10). Upon receiving this instruction, the compressor 109 compresses the M-plane image drawn on the image memory 107. When the compression of the M-plane image is completed, the compressor 109 outputs a compression end interrupt signal to the interrupt controller 106, so the interrupt controller 106 notifies the CPU 101 of the end of processing.

  Further, the CPU 101 outputs an activation signal to the drawing apparatus 105 via the IO port 113 in order to draw an image of the n-th band Y plane (step S10). As a result, the drawing apparatus 105 starts drawing processing of the Y plane image. The Y plane image is drawn on the image memory 107. When the drawing of the Y plane image is completed, the drawing apparatus 105 outputs a drawing end interrupt signal to the interrupt controller 106, so the interrupt controller 106 notifies the CPU 101 of the end of processing.

  The CPU 101 receives the completion of compression of the M-plane image from the interrupt controller 106 and proceeds to step S12 via step S11 upon receiving the completion of drawing processing of the Y-plane image. The CPU 101 instructs the compressor 109 via the IO port 113 to compress the image of the Y plane drawn by (Step S12). Upon receiving this instruction, the compressor 109 compresses the Y plane image drawn on the image memory 107. When the compression of the Y plane image is completed, the compressor 109 outputs a compression end interrupt signal to the interrupt controller 106, so the interrupt controller 106 notifies the CPU 101 of the end of processing.

  Further, the CPU 101 outputs an activation signal to the drawing device 105 via the IO port 113 in order to draw an image of the n-th band K plane (step S12). As a result, the drawing apparatus 105 starts drawing processing of the K plane image. The image of the K plane is drawn on the image memory 107. When the drawing of the K plane image is completed, the drawing apparatus 105 outputs a drawing end interrupt signal to the interrupt controller 106, so that the interrupt controller 106 notifies the CPU 101 of the end of processing.

  When the CPU 101 receives from the interrupt controller 106 that the compression of the Y plane image has been completed, the CPU 101 proceeds to step S14 via step S13 when the drawing processing of the K plane image has been completed. The CPU 101 instructs the compressor 109 via the IO port 113 to compress the image of the K plane drawn by (Step S14). Upon receiving this instruction, the compressor 109 compresses the K plane image drawn on the image memory 107. When the compression of the K plane image is completed, the compressor 109 outputs a compression end interrupt signal to the interrupt controller 106, so the interrupt controller 106 notifies the CPU 101 of the end of processing.

  On the other hand, the CPU 101 determines whether or not the value held by the variable n is the total number of bands, that is, whether or not the images of the C, M, Y, and K planes have been drawn and compressed for all the bands (steps). S15) If the value held by the variable n is not the total number of bands, the process proceeds to step S16, the value held by the variable n is updated by adding 1 (step S16), and the process returns to step S5. The processing after step S5 is performed for the next band.

  On the other hand, if the value held by the variable n is the total number of bands, the process proceeds to step S18, and the CPU 101 completes this process upon receiving a notification from the interrupt controller 106 that compression of the K-plane image has been completed.

  5A and 5B are flowcharts of processing for decompressing and printing a compressed image for each band (image of each plane). The processing according to the flowchart shown in FIGS. 5A and 5B is performed by the CPU 101 in parallel with the processing according to the flowchart shown in FIG. 4, and this parallel operation is realized by so-called multitask processing of the CPU 101. Is done.

  First, the values held by the variables i, j, l, and m are initialized to 0 (step S501). Next, when the drawing processing of the K-plane image of the first band is completed (that is, when the drawing processing of the K-plane image is completed from the interrupt controller 106), it is determined that the printing can be started. Then, the process proceeds to step S503 via step S502, and the print engine 112 is activated (step S503).

  Next, the value “1” is stored in the variable i (step S 504), and the CPU 101 prints the first band to the engine interface 111 via the IO port 113 in order to print the C plane image of the first band. The printing operation of the C plane image is instructed (step S505). As a result, the engine interface 111 reads the image of the C-plane of the first band on the image memory 107 via the memory controller 108, converts it into a video signal, and outputs it to the print engine 112. According to the signal, the first band C plane image is printed.

  Further, in parallel with this printing process, the CPU 101 instructs the decompressor 110 to decode (decompress) the compressed M plane image, Y plane image, and K plane image of the first band. The decompression of the compressed M plane image, Y plane image, and K plane image of the first band formed on the image memory 107 is instructed via the IO port 113 (step S505). The decompressor 110 reads and decompresses the compressed M-plane image, Y-plane image, and K-plane image of the first band via the memory controller 108, and restores the decompressed image to another area of the image memory 107. .

  Next, the CPU 101 determines whether or not the value held by the variable i is 0 (step S506). If the value held by the variable i is 0, the process proceeds to step S512. On the other hand, if the value held by the variable i is not 0, the process proceeds to step S507, and it is determined whether printing of the i-th band is completed (step S507).

  If i-th band printing has not been completed, the process advances to step S512. On the other hand, if the i-th band has been printed, the process advances to step S508 to determine whether the i-th band is the last band (whether the value held by the variable i is the total number of bands) (step S508). ).

  If the i-th band is the final band, the process proceeds to step S511, the value held by the variable i is initialized to 0 (step S511), and then the process proceeds to step S512. On the other hand, if the i-th band is not the last band, the process proceeds to step S509, and the value held by the variable i is updated by adding 1 (step S509), and the C-plane image of the i-th band is printed. Accordingly, the CPU 101 instructs the engine interface 111 to print the i-th band C-plane image via the IO port 113 (step S510). As a result, the engine interface 111 reads the image of the i-th C plane on the image memory 107 via the memory controller 108, converts it into a video signal, and outputs it to the print engine 112. In accordance with the signal, print processing of an image of the C plane of the i-th band is performed.

  Next, it is determined whether or not the value held by the variable j is 0 (step S512). If the value held by variable j is not 0, the process proceeds to step S517. On the other hand, if the value held by the variable j is 0, the process proceeds to step S513, and it is determined whether it is time to start printing the image of the M plane (step S513). If it is not time to start, the process advances to step S524. On the other hand, if it is time to start, the process proceeds to step S514, and the value “1” is stored in variable j (step S514).

  The CPU 101 instructs the engine interface 111 to print the M-plane image of the first band via the IO port 113 in order to print the M-plane image of the first band (step S515). As a result, the engine interface 111 reads the expanded first band M-plane image on the image memory 107 via the memory controller 108, converts it into a video signal, and outputs it to the print engine 112. Performs printing processing of the image of the M-plane of the first band in accordance with this video signal.

  Next, the CPU 101 performs the second band compressed M plane formed on the image memory 107 with respect to the decompressor 110 in order to decode (decompress) the image of the compressed M plane of the second band. Is instructed via the IO port 113 (step S516). Accordingly, the decompressor 110 reads and decompresses the compressed M-plane image of the second band via the memory controller 108, and restores the decompressed image to another area of the image memory 107.

  Next, it is determined whether or not printing of the jth band has been completed (step S517). If printing of the jth band has not been completed, the process proceeds to step S524. On the other hand, if the printing of the jth band is completed, the process proceeds to step S518, and it is determined whether the jth band is the final band (whether the value held by the variable j is the total number of bands) (step S518). ).

  If the j-th band is the final band, the process proceeds to step S523, the value held by the variable j is initialized to 0 (step S523), and then the process proceeds to step S524. On the other hand, if the j-th band is not the final band, the process proceeds to step S519, and the value held by the variable j is updated by adding 1 (step S519), and the M-plane image of the j-th band is printed. Accordingly, the CPU 101 instructs the engine interface 111 to print the image of the M-plane of the jth band via the IO port 113 (step S520). As a result, the engine interface 111 reads the image of the Mth plane of the jth band on the image memory 107 via the memory controller 108, converts it into a video signal and outputs it to the print engine 112. In accordance with the signal, print processing of an image of the M plane of the jth band is performed.

  Next, it is determined whether the j-th band is the final band (whether the value held by the variable j is the total number of bands) (step S521).

  If the j-th band is the final band, the process proceeds to step S522, and the CPU 101 instructs the decompressor 110 to decode (decompress) the compressed M-plane image of the (j + 1) -th band. The decompression of the (M + 1) th band compressed M plane image formed on the image memory 107 is instructed via the IO port 113 (step S522). Accordingly, the decompressor 110 reads and decompresses the compressed M-plane image of the (j + 1) th band via the memory controller 108 and restores the decompressed image to another area of the image memory 107.

  On the other hand, if the j-th band is not the final band, the process proceeds to step S524, and it is determined whether or not the value held by the variable l is 0 (step S524). If the value held by variable l is not 0, the process proceeds to step S529. On the other hand, if the value held by the variable l is 0, the process proceeds to step S525 to determine whether it is time to start printing the image of the Y plane (step S525). If it is not time to start, the process advances to step S536. On the other hand, if it is time to start, the process proceeds to step S526, and the value “1” is stored in variable l (step S526).

  In order to print the Y-plane image of the first band, the CPU 101 instructs the engine interface 111 to print the Y-plane image of the first band via the IO port 113 (step S527). As a result, the engine interface 111 reads the decompressed first band Y plane image on the image memory 107 via the memory controller 108, converts it into a video signal, and outputs it to the print engine 112. Performs printing of the Y plane image of the first band in accordance with the video signal.

  Next, the CPU 101 sends the second band compressed Y plane formed on the image memory 107 to the decompressor 110 in order to decode (decompress) the second band compressed Y plane image. Is instructed via the IO port 113 (step S528). Accordingly, the decompressor 110 reads and decompresses the compressed Y plane image of the second band via the memory controller 108, and restores the decompressed image to another area of the image memory 107.

  Next, it is determined whether or not printing of the l band has been completed (step S529). If printing of the l-th band has not been completed, the process proceeds to step S536. On the other hand, if the printing of the l band has been completed, the process proceeds to step S530, and it is determined whether the l band is the final band (whether the value held by the variable l is the total number of bands) (step S530). ).

  If the l-th band is the final band, the process proceeds to step S535, the value held by the variable l is initialized to 0 (step S535), and then the process proceeds to step S536. On the other hand, if the l-th band is not the final band, the process proceeds to step S531, and is updated by adding 1 to the value held in the variable l (step S531), and the image of the Y-plane Y plane is printed. Therefore, the CPU 101 instructs the engine interface 111 to print an image of the Y plane of the l-th band via the IO port 113 (step S532). As a result, the engine interface 111 reads the image of the 1st band Y plane on the image memory 107 via the memory controller 108, converts it into a video signal and outputs it to the print engine 112. In accordance with the signal, the printing process of the image of the Y plane of the l band is performed.

  Next, it is determined whether the l-th band is the final band (whether the value held by the variable l is the total number of bands) (step S533).

  If the l-th band is the final band, the process proceeds to step S536. On the other hand, if the l-th band is not the final band, the process proceeds to step S534, and the CPU 101 instructs the decompressor 110 to decode (decompress) the (Y + 1) -th band compressed Y plane image. Then, the decompression of the compressed (Y + 1) band Y plane image formed on the image memory 107 is instructed via the IO port 113 (step S534). Accordingly, the decompressor 110 reads and decompresses the compressed Y plane image of the (l + 1) band via the memory controller 108, and restores the decompressed image to another area of the image memory 107.

  Next, it is determined whether or not the value held by the variable m is 0 (step S536). If the value held by variable m is not 0, the process proceeds to step S541. On the other hand, if the value held by the variable m is 0, the process proceeds to step S537, and it is determined whether it is time to start printing the K-plane image (step S537). If it is not time to start, the process returns to step S506. On the other hand, if it is time to start, the process proceeds to step S538, and the value “1” is stored in the variable m (step S538).

  In order to print the first-band K-plane image, the CPU 101 instructs the engine interface 111 to print the first-band K-plane image via the IO port 113 (step S539). As a result, the engine interface 111 reads the decompressed first band K plane image on the image memory 107 via the memory controller 108, converts it into a video signal, and outputs it to the print engine 112. Performs printing of the image of the K-plane of the first band in accordance with this video signal.

  Next, the CPU 101 performs the second band compressed K plane formed on the image memory 107 with respect to the decompressor 110 in order to decode (decompress) the second band compressed K plane image. Is instructed via the IO port 113 (step S540). As a result, the decompressor 110 reads the decompressed K-plane image of the second band via the memory controller 108 and decompresses it, and restores the decompressed image to another area of the image memory 107.

  Next, it is determined whether printing of the mth band has been completed (step S541). If printing of the mth band has not been completed, the process returns to step S506. On the other hand, if printing of the m-th band is completed, the process proceeds to step S542, and it is determined whether the m-th band is the final band (whether the value held by the variable m is the total number of bands) (step S542). ).

  If the m-th band is the final band, this process ends. On the other hand, if the m-th band is not the final band, the process proceeds to step S543, and the value held by the variable m is updated by adding 1 (step S543), and the K-plane image of the m-th band is printed. Accordingly, the CPU 101 instructs the engine interface 111 to print the image of the Kth plane of the mth band via the IO port 113 (step S544). As a result, the engine interface 111 reads out the image of the m-th band K plane on the image memory 107 via the memory controller 108, converts it into a video signal and outputs it to the print engine 112. According to the signal, the m-th band K plane image is printed.

  Next, it is determined whether the m-th band is the final band (whether the value held by the variable m is the total number of bands) (step S545).

  If the m-th band is the last band, the process returns to step S506. On the other hand, if the m-th band is not the final band, the process proceeds to step S546, and the CPU 101 instructs the decompressor 110 to decode (decompress) the compressed (K + 1) -th image of the (m + 1) -th band. Then, the decompression of the (m + 1) -th band compressed K plane image formed on the image memory 107 is instructed via the IO port 113 (step S546). As a result, the decompressor 110 reads and decompresses the compressed K plane image of the (m + 1) th band via the memory controller 108 and restores the decompressed image to another area of the image memory 107.

  As described above, according to the present embodiment, the drawn plane image is immediately compressed (except for the C plane image) and is decoded and used at the time of printing, so only the printed plane image is decoded in the memory. As a result, the amount of memory used can be reduced compared to the conventional case where all plane images are stored in the memory in an uncompressed state.

  Also, since printing based on each plane image (excluding C plane images) is performed according to a simple rule, such as “decode each plane image at the time of printing”, color printing processing is performed with relatively simple processing. It can be performed.

  In the present embodiment, the printing process is started when images of C, M, Y, and K planes for one band are obtained. Therefore, the printing process is started after image data for one page is obtained. The printing process can be performed at a higher speed.

[Second Embodiment]
If the estimated rendering time of 4 planes in band units is larger than the execution time of the printing process, the drawing of the band is performed in advance before starting the printing apparatus, compressed and held, and the compressed band image is displayed at the printing timing. If printing is performed in a stretched manner, the processing described in the first embodiment can be performed even if a drawing apparatus with a low drawing speed is used, and a cheaper printing apparatus can be realized.

[Third Embodiment]
In the second embodiment, if the time prediction is performed for each plane of each band, and only band drawing of a plane that cannot be made in time is drawn before printing, a more efficient printing apparatus can be configured.

  Further, although the printing apparatus according to each of the above embodiments has been described as operating alone, the present invention is not limited to this, and has a function such as a copy function, a print function, a FAX function, a BOX function, or a file transmission function. You may make it apply the printing apparatus which concerns on each said embodiment to the printing mechanism part with which a multifunctional device is equipped.

  In the above-described embodiments, the colors used for printing are C, M, Y, and K. However, the above-described embodiments can also be applied to cases where colors other than these are used.

  Further, the printing method by the printing apparatus according to each of the above embodiments is not limited to a method according to a specific method, and mechanisms other than those described above are not particularly limited.

1 is a block diagram illustrating a hardware configuration of a printing apparatus according to a first embodiment of the present invention. It is a figure which shows the flow of the image drawing process based on print data. FIG. 5 is a diagram for explaining a printing operation performed by the printing apparatus according to the first embodiment of the present invention in time series. 5 is a flowchart of processing for receiving print data, rendering an image based on the print data, and compressing the image. It is a flowchart of a process for decompressing and printing a compressed image for each band (image of each plane). It is a flowchart of a process for decompressing and printing a compressed image for each band (image of each plane).

Claims (5)

Receiving means for receiving print data;
Drawing means for drawing an image based on the print data for each band;
Printing means for performing printing based on the image drawn by the drawing means,
The drawing means includes
For each band, a color image drawing means for drawing an image for each color used at the time of printing,
Compression means for compressing the image drawn by the color image drawing means for the second color other than the first color used first when printing each band, immediately after the drawing,
The printing means includes
First printing means for performing printing based on an image drawn by the color image drawing means for the first color;
When performing printing based on the image drawn by the color image drawing means for the second color, decoding means for decoding the image immediately before that,
A printing apparatus comprising: a second printing unit that prints an image decoded by the decoding unit.   The colors used at the time of printing are C, M, Y, and K, and the color image drawing unit draws a C plane image, an M plane image, a Y plane image, and a K plane image for each band. The printing apparatus according to claim 1.   The printing apparatus according to claim 2, wherein the first color is C, and the second color is M, Y, or K. 4.   A multifunction machine comprising the printing apparatus according to claim 1. A receiving process for receiving print data;
A drawing step of drawing an image based on the print data for each band;
A printing step for performing printing based on the image drawn in the drawing step,
The drawing step includes
For each band, a color image drawing process for drawing an image for each color used during printing,
A compression step of compressing the image drawn in the color image drawing step for the second color other than the first color used at the time of printing each band immediately after the drawing,
The printing process includes
A first printing step for performing printing based on the image drawn in the color image drawing step for the first color;
When performing printing based on the image drawn in the color image drawing step for the second color, a decoding step for decoding the image immediately before that,
And a second printing step of printing the image decoded in the decoding step.

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