JPH09193482A - Printing data transfer device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printing data transfer device which can shorten the total of compression time and transfer time required for transfer of printing data. SOLUTION: A compression time measuring circuit 17 determines the time required for compressing one page in the previous measurement. A compression, transfer indication means 19 determines a minimum number of pages such that the transfer time under condition of non-compression is longer than the previous compression time of one page. A transfer circuit 14 transfers printing data corresponding to the minimum number of pages from the top thereof without compressing the data to a printing device 12. In parallel, pages to be transferred next are compressed by means of a compressing circuit 15. After completion of transfer of non-compression data, compressed data are transferred to the printing device 12 via the circuit 14. Since compression and transfer are performed parallelly to each other, the total transfer time can be made shorter. And transfer can be effected without disturbing the order of pages.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a print data transfer device for transferring print data consisting of character codes and control codes or print data after being expanded into image information to a printing device, and particularly compressing the print data. The present invention relates to a print data transfer device that shortens transfer time.

[0002]

2. Description of the Related Art Print data created by a document creation device such as a host computer is printed in the form of code information such as character codes and various control codes, or in the form of image information developed for each dot to be printed. Transferred to the device. The time required to obtain the printed matter after issuing the print instruction for the created document is the time to transfer the code information and image information to the printing device, and the printing device prints on the recording paper based on the transferred print data. It is the sum of the time to print. Therefore, by shortening the transfer time, the time required to finally obtain a printed matter can be shortened.
Further, by shortening the transfer time of the print data, the document creating apparatus can be released from the processing for printing at an early stage. Therefore, various techniques have been proposed for reducing the transfer time of print data.

Japanese Patent Laid-Open No. 3-275370 discloses a print data transfer apparatus which transfers image information after compressing it. In this device, a buffer device having a buffer memory is provided between the printing control device and the printing device on the image information sending side. The print control device compresses the image information and transfers it to the buffer device. The buffer device temporarily holds the compressed print data that has been sent, expands the original image information, and sends it to the printing device in sequence.

[0004]

In order to compress and transfer print data, a time for performing compression processing is required in addition to the transfer time. For example, print data for multiple pages
When the data is compressed page by page and transferred, both the time for compressing each page and the time for transferring the compressed data are required. Also, the time required for compression is
It changes individually depending on the print data to be compressed.
Further, the amount of data after compression may be larger than that before compression. Therefore, the sum of the compression time and the time to transfer the compressed data may be longer than the time required to transfer the print data without compression, and even if compression is performed, efficient transfer is not always required. There is a problem that you cannot do it.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a print data transfer device capable of shortening the transfer time of print data.

[0006]

According to a first aspect of the present invention, there is provided a print data storage unit for storing print data, and a first print area of the print data stored in the print data storage unit. A compression unit for compressing the print data, and when the compression unit is compressing the print data corresponding to the first print region, in parallel with this, the print data of the second print region as another region is predetermined. First transfer means for transferring to the transfer destination without passing through the compression means, transfer of print data in the first print area by the first transfer means, and compression of print data in the second print area by the compression means. The print data transfer device is provided with a second transfer unit that transfers the print data in the second print area, which has been compressed when both of them are completed, to a predetermined transfer destination.

That is, according to the first aspect of the invention, while the print data corresponding to the first print area is being compressed, the pre-compression print data corresponding to the second print area is transferred in parallel with this. When the compression process is completed, the compressed print data is transferred. Since the uncompressed print data is transferred in parallel while the print data is compressed, the time required to transfer the print data is shortened.

According to the second aspect of the invention, the print data storage means for storing the print data, and the amount corresponding to the print area of a predetermined fixed size among the print data stored in the print data storage means. Of the print data stored in the print data storage means and the amount of print data that can be transferred during the time obtained by the compression time acquisition means. To a predetermined transfer destination without compressing the print data, and the print data stored in the print data storage means in parallel with the print data being transferred by the first transfer means. Of the data, a compression unit that compresses an amount of print data that corresponds to a print area of a predetermined size to be transferred next to the print data that is currently transferred by the first transfer unit, When the compression of the print data by the compression unit and the transfer of the print data by the first transfer unit are completed, the print data after being compressed this time by the compression unit is transferred to a predetermined transfer destination. And a second transfer means for controlling the print data transfer device.

That is, according to the second aspect of the invention, the uncompressed print data that can be transferred in the time required for one compression process is transferred, and at the same time, the print data in the order to be transferred next is transferred. Compress. Then, when the transfer of the uncompressed print data and the compression processing of the print data are completed, the compressed print data is transferred. By performing compression processing in parallel with the transfer of uncompressed print data in this way,
The total time required for compression and transfer is reduced.
In addition, by compressing the print data that should be transferred next to the print data that has been transferred without being compressed, the print data can be transferred without breaking the transfer order.

According to the third aspect of the present invention, print data storage means for storing print data, and print data stored in the print data storage means are printed in unit prints for each amount corresponding to a print area of a predetermined size. Order information adding means for dividing the data into pieces and adding order information indicating the order of printing to these, and any one of the unit print data to which the order information is added by the order information adding means is transferred in a predetermined manner. A first transfer unit that transfers first, a compression unit that compresses another arbitrary unit print data from the time when the first transfer unit starts the transfer of the arbitrary unit print data, and a first transfer unit. When the transfer means has finished transferring one unit print data, and the compression means has not finished compressing another one unit print data, the compression or transfer has not been performed yet. Transfer of one unit print data and continue transfer instruction means for instructing the first transfer means or Re, first
When the other transfer unit of one unit print data has finished transferring one unit print data, the other transfer unit of the unit print data has been compressed by the compressing unit. The print data transfer apparatus is provided with the second transfer unit that transfers first.

That is, according to the third aspect of the invention, the print data is divided into predetermined print areas, and order information indicating the print order is added to them. Then, the transfer of the arbitrary print data after the division and the compression of the other arbitrary one print data are performed in parallel. When the transfer of the print data after the division is completed and the compression process of the print data is not completed, the transfer of the next arbitrary one print data is continuously performed. If the compression process is completed when the transfer of the divided print data is completed, the compressed print data is transferred. If the order information is added in this way, the printing order can be determined based on this by the printing device side.
The divided unit print data can be transferred in any order.

According to another aspect of the present invention, the print data storage means for storing print data, and the print data stored in the print data storage means are subjected to unit printing for each amount corresponding to a print area of a predetermined size. Sequence information adding means for dividing the data into data and adding order information indicating the order of printing to each of them, and whether or not each unit print data to which the order information is added by the order information adding means has a predetermined data format A data format discriminating means, a first transfer means for transferring any one unit print data discriminated by the data format discriminating means not to be in a predetermined format to a predetermined transfer destination, and the first transfer. Compression means for compressing another unit print data which is determined to have a predetermined format from the time when the means starts transferring any one unit print data,
When the first transfer unit finishes the transfer of one unit print data, the compression unit is determined to have a predetermined format.
A continuous transfer instruction means for instructing the first transfer means to transfer any one unit print data which has not been transferred among the unit print data which is not in a predetermined format when the compression of one unit print data is not completed; , When the first transfer unit finishes transferring one unit print data, and when the compression unit finishes compressing another unit print data determined to have a predetermined format And a second transfer unit that transfers one unit of print data to a predetermined transfer destination in the print data transfer device.

That is, according to the fourth aspect of the invention, the print data is divided into print areas of a predetermined size, order information indicating the printing order is added to the print areas, and the print data after the division has a predetermined size to be compressed. Determine if it is a format. Then, compression of print data of a predetermined format and transfer of print data of other formats are performed in parallel.

For example, it is assumed that the print data is divided into pages and that the pages represented by the raster data and the pages represented by the code data such as the character code are mixed. Since one page of compression processing is performed while transferring uncompressed data, if the time for compressing one page is significantly shorter than the time for transferring one page of uncompressed data, the compression processing and transfer The time when the processing is performed in parallel is shortened. Therefore, by preferentially compressing a page that takes a long time to compress one page, the time during which the compression process and the transfer of uncompressed data are performed in parallel increases, and the transfer efficiency improves. Normally, the amount of raster data is larger and the time required for compression is longer than in the case of code data, so the transfer efficiency is improved by determining the page suitable for compression based on the type of print data. I am trying to

According to a fifth aspect of the present invention, print data storage means for storing print data, and print data stored in the print data storage means are subjected to unit printing for each amount corresponding to a print area of a predetermined size. Order information adding means for dividing the data into data and adding order information indicating the order of printing to the data, and data amount calculating means for obtaining the data amount of each unit print data to which the order information is added by the order information adding means And a first selecting unit for selecting one unit print data to be transferred next in the ascending order of the data amount obtained by the data amount calculating unit, and then a compressing process in the descending order of the data amount obtained by the data amount calculating unit. Should be 1
Second selection means for selecting one unit print data, and first
First transfer means for transferring one unit print data selected by the selecting means to a predetermined transfer destination, and selected by the second selecting means from the time when the first transfer means starts transferring the unit print data. A compression unit for compressing the selected unit print data and a unit print selected by the second selection unit when the first transfer unit completes the transfer of the unit print data. Continuous transfer instructing means for causing the first selecting means to select one unit print data having the next smallest amount of data when the data compression is not completed, and transferring the selected unit print data to a predetermined transfer destination by the first transfer means; When the compression means has completed the compression of one unit print data selected by the second selection means at the time when the first transfer means has completed the transfer of one unit print data, the end of the compression The unit print data and is provided with a second transfer means for transferring a predetermined transfer destination to the print data transfer device.

That is, according to the fifth aspect of the invention, the print data is divided into print areas of a predetermined size, order information indicating the printing order is added to them, and the data amount of the print data after the division is obtained. . Then, the data having a large amount of data is preferentially compressed, and in parallel with this, the data having a small amount of data is preferentially transferred without being compressed. Usually, the larger the amount of data, the longer it takes to compress. Therefore, if the print data with a small amount of data is transferred in parallel with the compression of the print data with a large amount of data, the ratio of the period in which the transfer and the compression are performed at the same time is increased. It is possible to increase the transfer efficiency.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an outline of the configuration of a printing system using a print data transfer device according to an embodiment of the present invention. This system is composed of a print data transfer device 11 for transmitting print data, and a print device 12 for receiving the sent print data and printing it on a recording sheet in response to the print data. The print data transfer device 11 includes a transfer buffer memory 13 that stores print data to be transferred.
A transfer circuit 14 for transferring print data to the printing device 12 through a communication cable, and a compression circuit 15 for compressing the print data. The compression circuit 15 is configured to compress the print data page by page. Any compression method may be used, but a reversible one that can obtain the same data as before compression when decompressed is preferable.

The output of the compression circuit 15 is input to the compression buffer memory 16 which temporarily stores the compressed data. The transfer circuit 14 stores compressed print data stored in the compression buffer memory 16 (hereinafter referred to as compressed data) or uncompressed print data stored in the transfer source buffer memory 13 (hereinafter referred to as raw data). Any of the above (referred to) is transferred to the printing device 12. The compression time measuring circuit 17 is a circuit that measures the time required for the compression circuit 15 to compress one page of print data.

The compression time estimation circuit 18 uses the compression time measured by the compression time measurement circuit 17 up to the previous time as the basis.
This is a circuit that estimates the time required to compress the next page.
The compression / transfer instruction circuit 19 is a circuit that determines, based on the time estimated by the compression time estimation circuit 18, which page of print data is to be compressed next. In addition, the compression circuit 15
Is given to the transfer circuit 14, and at the same time, an instruction to transfer up to the page before the page to be compressed in the raw data state to the printing device 12 is given to the transfer circuit 14.

For example, assuming that the time for transferring the raw data for one page is 10 seconds and the time estimated by the compression time estimation circuit 18 is 15 seconds, while the raw data for two pages is being transferred. Then, the compression of the print data for one page can be completed. Therefore, if the next page to be transferred is the fifth page, the sixth and seventh pages are transferred as raw data, and the print data of the eighth page is compressed by the compression circuit 15. As a result, the compressed data of the eighth page can be transferred after the raw data of the sixth and seventh pages can be transferred, and the page order is not broken. If the guess is correct, the compression processing of the eighth page is completed when the transfer of the seventh page is completed, so that there is no idle time for data transfer, and efficient transfer can be performed.

The printing device 12 is a print data transfer device 11
It has a reception buffer memory 21 for accumulating raw data or compressed data sent from the device, and a compression discrimination circuit 22 for discriminating whether the received data is compressed data or raw data. The decompression circuit 23 is a circuit that decompresses compressed data and restores the compressed data to the state before compression. Printing unit 2
Reference numeral 4 is a portion for printing on recording paper based on print data. The data determined as raw data is sent from the reception buffer memory 21 to the printing unit 24 as it is, and the data determined as compressed data is decompressed by the decompression circuit 23.
It is sent to the printing unit 24 and printed.

FIG. 2 shows an outline of the circuit configuration of the print data transfer apparatus shown in FIG. The print data transfer device 11 is a CPU that plays a central role in various controls.
A (central processing unit) 31 is provided. The CPU 31 has
Various circuit devices are connected via various buses 32 such as a data bus and an input / output bus. Of these, the ROM (Read Only Memory) 33 is a read-only memory that stores programs and fixed data. A RAM (Random Access Memory) 34 is a working memory that stores data temporarily required for executing a program.

The buffer memory 35 is a memory for storing raw data before being compressed and compressed data after being compressed. The compression circuit 36 is a circuit that compresses print data according to a predetermined algorithm. Transfer control circuit 37
Is a circuit for sending raw data or compressed data to a printing device via a communication cable. The DAM (Direct Memory Access) controller 38 directly transfers the compressed data or raw data stored in the buffer memory 35 without passing through the CPU 31.
It is a circuit to transfer to.

An interrupt signal indicating the end of the compression process output from the compression circuit 36 is input to the CPU 31. The CPU 31 measures the compression time required to compress the print data for one page by measuring the time from when the compression start instruction is issued until the interrupt signal is input from the compression circuit 15. Further, the ROM 33 stores the time required to transfer 1 byte. CPU
Reference numeral 31 multiplies the transfer time of 1 byte by the total number of bytes of 1 page to obtain the time required to transfer 1 page of raw data. Then, the page to be compressed next is obtained based on the compression time and the transfer time of the raw data per page.

FIG. 3 shows the flow of processing performed by the print data transfer apparatus. First, raw data to be transferred is prepared in the buffer memory 35. After that, CPU3
1 initializes various parameters (step S1).
01). The transfer page number (i) representing the page number to be transferred next and the continuous transfer page number (x) representing the number of pages to be transferred during one compression process are each “1”.
Initialize to In addition, the compression time parameter (a) for holding the time required for compression is initialized to "0", and the compressed data size (b) of the parameter indicating the data size after compression is initialized to "0".

Next, the CPU 31 determines whether or not the continuous transfer page number (x) is "0" (step S).
102). The continuous transfer page number (x) represents the number of pages of raw data that should be transferred in parallel with the print data for one page next time while compressing the print data for one page.
When the value of is 0, it means that the raw data is not transferred and only the compression is performed. Therefore, when the continuous transfer page number (x) is "0" (step S102; Y),
Only the print data of the i-th page is compressed (step S
103). When the continuous transfer page number (x) is not "0" (step S102; N), the raw data for the "i" th page to the "x" page is transferred, that is, from the ith page to the (i + x-1) th page. Transfer raw data. Further, the print data of the (i + x) th page is compressed in parallel with the transfer of the raw data (step S104). Thus, the compression process of the (i + x) th page is performed during the transfer of the raw data.

When the compression process is completed, the CPU 31 determines whether the data size after compression is larger than the size of raw data for one page before compression (step S).
105). When the data size after compression becomes larger than the data size before compression (step S105;
Y), the raw data of the (i + x) th page is transferred (step S106), and the compressed data is discarded. When the data size after compression is not larger than the data size before compression (step S105; N), the compressed data of the (i + x) th page is transferred to the printing device 12 (step S10).
7).

After the transfer of the (i + x) th page is completed, "1" is added to the variable (i) representing the page number to be transferred next to update the page number (step S108). Although not shown in FIG. 3, the CPU 31 substitutes the time required for compression of the (i + x) th page into a variable (a) and the data size after compression into a variable (b). When the size of the compressed data becomes larger than the size of the raw data for one page, the size of the raw data for one page is substituted into the variable (b).

Based on the compression time (a), the data size after compression (b), the number of bytes of raw data for one page (c), and the transfer time per byte (d), the CPU 31
The value of the number of pages (x) of raw data to be continuously transferred during the next compression is calculated (step S109). The number of continuous transfer pages (x) is obtained from the conditional expression shown below. (X-1) cd <a = <xcd (x is an integer) Expression (1) However, when the relationship of the following expression is established, x is set to “0” and only the compression is performed without transferring the raw data. Set to do. cd <2a (2) formula

In the equation (1), the time (xcd) for transferring the raw data for x pages is longer than the time (a) for compressing the print data for one page, and the minimum "x" is calculated. There is. That is, when the raw data is transferred page by page, the transfer time of the raw data is longer than the time required to compress the print data for one page, and the minimum number of pages is obtained. If the estimation of the time required for the next compression is correct, the compression process for one page is completed before the transfer of the raw data for x pages is completed, so that the transfer of the compressed data is completed immediately after the transfer of the raw data is completed. You can start.

The equation (2) determines that the total transfer time is shortened by alternately repeating only the compression process and the transfer of the compressed data, rather than performing the transfer of the raw data and the compression process in parallel. doing. That is, the time required when the compression process of the next page is performed in parallel during the transfer of raw data and the compressed data is transferred after the transfer of the raw data is T1.
Then, T1 is expressed by the following equation. T1 = cd + bd (3) On the other hand, T2, which is the time required to compress all two pages and transfer the compressed data after compression, is expressed by the following equation. T2 = 2a + 2bd (4) Formula

If T2 becomes smaller than T1, the total transfer time will be shorter if the compression process and the transfer of the compressed data are repeated without transferring the raw data. This can be expressed by the following equation. cd + bd> 2a + 2bd Expression (5) If the transfer time (bd) of compressed data is sufficiently short, if the relationship shown in Expression (2) holds, it is better not to perform raw data transfer and compression processing in parallel. , The transfer time becomes shorter.

A page ahead by the number of continuous transfer pages (x) thus obtained is a page to be compressed next time. Therefore, the CPU 31 compares the number of remaining pages to be transferred with the value of "x" (step S110). If the value of "x" is larger than the number of remaining pages (step S11)
0; Y), there is no page to be compressed among the remaining pages, so the remaining pages are sequentially transferred as raw data (step S111). If the value of "x" is not larger than the number of remaining pages (step S11)
0; N)), and there is a page to be compressed among the remaining pages, so the processing returns to step S102 and continues.

FIG. 4 shows an example of the raw data transfer time, the compression time, and the compressed data transfer time.
Here, from page 1 to page 11,
The raw data transfer time, the compression time required to compress each page, and the compressed data transfer time are shown. In addition, the raw data of each page is assumed to be image data after being developed for each dot. If the size of the image area per page is the same, the size of the image data, that is, the raw data is the same. Here, the time required to transfer one page of raw data is 10 seconds for each page. The compression time changes individually depending on the contents of the image data of each page. Each compression time is 12 seconds for the first and second pages, each 8 seconds for the compression of the third to fifth pages, and the sixth to the eighth. 4 seconds each for page compression, 9th
~ It takes 6 seconds each to compress the 11th page. Further, since the amount of data after being compressed is different, it takes 4 seconds to transfer the compressed data of the first and second pages, and 2 seconds to transfer the compressed data of the third to 11th pages. doing.

FIG. 5 schematically shows a state in which the print data represented by each time is transferred in FIG. Each horizontal axis in FIG. 5 represents time. The solid line in the figure represents the period during which raw data is being transferred, the dotted line represents the period during which compression processing is being performed, and the shaded part represents the period during which compressed data is being transferred. When all the pages are transferred as raw data (a in the figure), the transfer time (51) of each page takes 10 seconds, so the transfer time (52) of the print data for 11 pages is 110 seconds. .
In the case of performing compression processing for one page and then transferring compressed data for each page repeatedly (b in the same figure), the total processing time (53) becomes 104 seconds. In the first page and the second page, the sum (54) of the compression time and the transfer time of the compressed data is 16 seconds, which is longer than 10 seconds when the raw data is transferred as it is.

When the raw data transfer and the compression process are performed in parallel according to the flow chart shown in FIG. 3 (c in the same figure), the total transfer time (55) is 76 seconds, which is a significant transfer. The time has been shortened. In FIG. 5c, the first page (P
While the 1) is being transferred as raw data, the second page (P
The compression process of 2) is performed in parallel. In the initial state,
Since the time required for compression is unknown, the second page is unconditionally compressed in parallel with the transfer of the first page. Here, since the compression time of the second page is longer than the transfer time of the raw data of the first page, the end of the compression process is waited for 2 seconds after the end of the transfer of the raw data, and the period during which the data is not transferred is Has occurred.

Since the time required for the compression of the second page was longer than the transfer time of the raw data for one page, the third page (P3) and the fourth page (P4) are executed in parallel with the next compression process. ) 2 pages of raw data are transferred. This makes the raw data transfer time longer than the compression time. The fifth page (P5) in the order to be transferred next to the fourth page is compressed in parallel, and after the completion of the raw data transfer of the fourth page,
The compressed data of the fifth page is being transferred. The compression time of the fifth page is the transfer time of the raw data of one page 10
Since it was 8 seconds, which was shorter than the second, the compression processing of the 7th page (P7) was performed in parallel while the raw data of the 6th page (P6) was transferred, and after the transfer of the 6th page was completed, 7 pages of compressed data are being transferred. The time required to compress the seventh page is 4 seconds, which is twice as long as the transfer time (10 seconds) for one page. Therefore, (2)
The relationship shown in the equation holds.

Therefore, the raw data is not transferred in parallel while the eighth page (P8) is being compressed. Further, since the compression time of the eighth page was also 4 seconds, the raw data was not transferred during the compression process of the ninth page (P9). Since the compression of the 9th page took 6 seconds, the relation of the equation (2) was not established, and the 10th page (P10) was transferred as raw data, while the compression of the 11th page (P11) was performed in parallel. Is going. After the transfer of the 10th page is completed, the 1st page
One page of compressed data is being transferred. By thus performing compression and transfer in parallel, the total time required for transfer of print data is shortened. In addition, based on the time required for the previous compression, the number of pages to be transferred as raw data is calculated in parallel with the compression, and the page next to the page transferred by the raw data is compressed. The print data is transferred without breaking the order.

Next, it will be explained that the transfer time is surely shortened by performing the transfer according to the flow chart shown in FIG. 3 as compared with the case of the flow transfer shown in FIGS. 5 (a) and 5 (b).

The average compression time is (a), the average data size after compression is (b), the data size of raw data for one page is (c), and the time for transferring one byte is (d). . Further, the number of pages of raw data transferred during the compression process of one page is (x). The transfer time required to transfer an "x" page with only raw data is given by: xcd (6) Expression Also, as shown in the flow chart of FIG. 3, one page is compressed while transferring only (x−1) pages of raw data, and the compressed data is transferred after the raw data is transferred. The time required for transfer is expressed by the following equation. (X-1) cd + bd = xcd-cd + bd Expression (7)

When the data size (b) after compression becomes larger than the data size (c) of the raw data, the raw data is transferred, so that bd = <cd always holds. Therefore, there is the following relationship between the expressions (6) and (7). xcd> = (x−1) cd + bd (8) That is, the data amount represented by the formula (7) is equal to or smaller than the data amount when only the raw data represented by the formula (6) is transferred. .

As shown in FIG. 5B, the transfer time required when the compression process and the transfer of the compressed data are alternately performed is expressed by the following equation. x (a + bd) Expression (9) In order for the transfer time shown in Expression (7) to become shorter than the transfer time shown in Expression (9), the following expression must be satisfied. x (a + bd)> (x-1) cd + bd (10) Formula When this is modified, the following formula is obtained. ax + xbd> (x-1) cd + bd (11) Formula ax> (x-1) cd- (x-1) bd (12) Formula

In the case of the expression (7), since the raw data is transferred and compressed in parallel, it is necessary to compare the transfer time of at least two pages. Also, the shorter the compression time is, the smaller the effect of shortening the transfer time by performing the compression in parallel with the transfer of the raw data is. Therefore, the case where one page is compressed during the transfer of one page is a comparison target. Good.
Therefore, when x is “2”, the relationship of the expression (12) may be established. Substituting "2" for x, equation (12) is expressed as the following equation. 2a> cd-bd Expression (13) If the transfer time (bd) of compressed data is small and can be ignored, Expression (13) becomes the following expression. 2a> cd (14) When such a relationship is not established, that is, when the time (2a) that is twice the compression processing time is shorter than the transfer time (cd) of the raw data for one page, that is, ( When the relation of the expression (2) is established, the raw data need not be transferred in parallel with the compression processing. By doing so, the transfer time does not become longer than in the case where the compression processing and the transfer of the compressed data are alternately performed.

First Modified Example

In the embodiments described so far, the print data is transferred so as not to break the page order.
In the modified example, the order information indicating the order of printing is added to the print data, and the print data is transferred in an arbitrary order.
The printing device 12 rearranges the received print data based on the order information added to the received print data to perform printing. The configuration of the print data transfer device is
Since it is the same as that shown in FIGS. 1 and 2, its description is omitted, and only the flow of operation will be described below.

FIG. 6 shows the flow of processing performed by the print data transfer apparatus in the first modification. After the raw data to be transferred is prepared in the buffer memory 35,
The CPU 31 adds order information representing the printing order to the print data for each page. After that, various parameters are initialized (step S201). here,
The transfer page number (i) representing the page number to be transferred is initialized to "1", and the compressed page number (x) representing the page number to be compressed is initialized to "2". That is, the first
The page number is transferred as raw data, and initialization is performed so that the compression processing of the second page is performed in parallel with this. other than this,
The compression time parameter (a) for holding the time required for compression is initialized to "0", and the compressed data size (b) representing the data size after compression is initialized to "0".

Next, the CPU 31 determines the compression page number (x)
Is determined to be the same as the transfer page number (i) (step S202). When they match, it means that the total transfer time is shorter when only the compression process is executed than when the raw data is transferred in parallel with the compression process. Therefore, when the compressed page number (x) matches the transfer page number "i" (step S202; Y), the CPU 31 only compresses the print data of the xth page (step S203). If "x" and "i" do not match (step S202; N), the raw data of the i-th page and the compression processing of the print data of the x-th page are performed in parallel (step S204).

When the transfer of the raw data of the i-th page is completed, the CPU 31 determines whether or not the compression processing of the x-th page is completed (step S205). At the time when the transfer of the raw data for one page of the i-th page is completed, if the compression processing of the x-th page is not completed yet (step S205; N), the i-th page is compressed until the compression processing of the x-th page is completed. After that, the raw data of another one page is sequentially transferred (step S206). A page other than the x-th page that has been compressed is selected as the page to be transferred as raw data.

The CPU 31 transfers the raw data until the compression processing of the xth page is completed, and then compares the data size of the compressed data of the xth page with the data size of the raw data of one page ( Step S207). When the data size after compression is larger than that of the raw data (step S207; Y), the raw data of page x is transferred (step S208) and the compressed data is discarded. At this time, the order information indicating the printing order of the page is added to the beginning of the data to be transferred.

When the data size after compression is not larger than that of the raw data (step S207; N), the xth
The order information is added to the head of the compressed data of the page and transferred to the printing device 12 (step S209). After that, CP
Next, U31 updates the transfer page number (i) representing the page number to be transferred as raw data to the current value plus "1". Further, the compressed page number (x) representing the page number to be compressed next is changed to a value obtained by adding "1" to the updated transfer page number (i) (step S21).
0).

The CPU 31 determines whether the time which is twice the time required for the previous compression is shorter than the transfer time of the raw data for one page (step S211). That is, it is checked whether or not the relationship of 2a <cd shown in the equation (2) is established. As described above, this determines whether or not the raw data should be transferred in parallel with the compression processing. When the time which is twice the compression time is shorter (step S211; Y), the compression page number (x) is changed to the same value as the transfer page number (i) (step S21).
2). Then, it is determined whether the compressed page number (x) is within the range of the remaining pages to be transferred (step S213). When the compressed page number is out of the range of the remaining pages (step S213; N), there is no page to be compressed, so all the remaining pages are transferred as raw data (step S214). If the compressed page number (x) is within the range of the remaining pages (step S21)
3; Y), step S202 also returns and continues the process.

As described above, when the order information indicating the printing order is added and transferred, the order of pages to be transferred can be set arbitrarily, so that the page to be compressed next can be easily obtained. Therefore, the processing can be simplified as compared with the case of transferring without breaking the page order.

Second modification

Since the compression process for one page is performed during the transfer of the raw data, if the time for compressing one page is shorter than the time for transferring the raw data for one page, the compression process and the transfer are performed accordingly. The processing time is reduced in parallel. Therefore, by preferentially compressing a page that takes a long time to compress one page, the time during which the compression process and the raw data transfer are performed in parallel increases, and the total transfer time can be shortened.

Generally, the raster data after being developed into an image has a large data amount, and its compression also takes time. On the other hand, the print data represented by the character code or the control code has a smaller data amount per page than the raster data, and the compression time is often short.
Therefore, in the second modification, when the print data in which the code data and the raster data pages are mixed is transferred, the raster data pages are preferentially compressed.

FIG. 7 shows the flow of processing performed by the print data transfer apparatus in the second modification. CP
The U 31 adds order information indicating the printing order to the print data of each page and initializes various parameters prior to transfer (step S301). next time,
The transfer page number (i) representing the page number represented by the code data to be transferred without compression is initialized to "1". Further, the CPU 31 sequentially determines whether or not the print data is raster data from the first page, and sets the number of the raster page that first appears in the page order as the compressed page number (x). In addition, a compressed data size (a) representing the data size after compression and a compression time (b) representing the time required for compression are initialized to "0".

Next, the CPU 31 determines whether or not the compressed page number (x) is "0" (step S).
302). When the compressed page number (x) is “0”, the total transfer time is better when only the compression process is executed than when the page represented by the code data is transferred in parallel with the compression process of the raster page. It means shortening. Therefore, when the compressed page number (x) is "0" (step S302; Y), only the raster data of the xth page is compressed (step S203). When "x" is not "0" (step S302; N), the transfer of the i-th page code data (raw data) and the compression processing of the x-th page raster data are performed in parallel (step S3).
04).

When the transfer of the raw data of the i-th page is completed, it is judged whether or not the compression processing of the x-th page is completed (step S305). If the compression processing of the x-th page is not yet completed when the transfer of the raw data of the i-th page is completed (step S305; N), the i-th page is continued until the compression processing of the x-th page is completed. , Another one page represented by the code data is sequentially transferred (step S306). A page other than raster data, which has not been transferred yet, is selected as the page to be transferred as raw data.

After transferring the raw data until the compression processing of the x-th page is completed, the CPU 31 determines the size of the compressed data of the x-th page and the size of the raster data of one page before compression. Compare (step S3)
07). If the data size after compression is larger than that before compression (step S307; Y), the xth page is transferred with the order information added to the beginning of the raster data before compression (step S308), and the compressed data is transferred. Discard. When the data size after compression is not larger than that before compression (step S307; N), the order information of the page is added to the compressed data of the x-th page and transferred to the printing device 12 (step S309). After that, the CPU 31 determines whether or not the page represented by the raster data exists in the remaining pages that have not been transferred (step S310).

If there is no page represented by raster data among the remaining pages to be transferred (step S31)
0; N), the remaining pages are all transferred as raw data (step S311). When there is a page represented by raster data in the remaining remaining pages to be transferred (step S310; Y), the time required for the previous compression is twice as long as the raster data for one page. It is determined whether it is shorter than the transfer time (step S312). That is, it is checked whether or not the relationship of 2a <cd shown in the equation (2) is established. If twice the compression time is not shorter (step S312; N), the number of the next raster page is set to the compression page number (x) (step S31).
3). When the time that is twice the compression time is shorter (step S312; Y), "0" is assigned to the compression page number (x) because the transfer time is shorter when only compression processing is performed (step S314).

The CPU 31 assigns the transfer page number (i) representing the page number to be transferred with the code data as it is,
The value is changed to the value obtained by adding "1" to the current value (step S3).
15). However, when the value of the transfer page number (i) matches the compressed page number (x), the value of the page number which is different from “x” and which is not the raster page is set.
Next, it is determined whether or not the value of the updated compressed page number (x) is within the range of the remaining pages to be transferred (step S316).

When the compressed page number (x) is out of the range of the remaining pages (step S316; N), there is no page to be compressed anymore, so all the remaining pages are transferred as code data (raw data) ( Step S311). When the compressed page number (x) is within the range of the remaining pages (step S316; Y), step S302 also returns and the transfer processing of the remaining pages is continued. As described above, the page of raster data suitable for compression is preferentially subjected to the compression process, whereby the transfer time can be effectively shortened.

Third Modification

In the third modified example, the compression processing is preferentially performed for the print data having a large amount of print data per page, and the raw data is preferentially transferred for the one having a small data amount. Normally, the larger the amount of data, the longer the time required for compression. Therefore, by performing transfer and compression in accordance with such a priority order, it is often possible to transfer raw data of a plurality of pages during compression of one page. As a result, the ratio of the time during which the compression process and the raw data transfer are performed in parallel increases, and the transfer efficiency can be improved.

FIG. 8 shows the flow of processing performed by the print data transfer apparatus in the third modification. CP
U31 adds the order information indicating the printing order to the print data for each page, and sorts the print data in the order of pages having the largest amount of print data for one page (step S401). Hereinafter, the page order after sorting will be referred to as a sorted page number. Next CPU3
1 initializes various parameters (step S40).
2). The compressed sort page number (x), which represents the page to be compressed and transferred by the sort page number, is set to "1", and the page to be transferred as it is without being compressed is the sort page number (x). Set i) to the total number of pages. In addition, a compressed data size (a) representing the data size after compression and a compression time (b) representing the time required for compression are initialized to "0".

Next, the CPU 31 determines whether the compression sort page number (x) matches the transfer sort page number (i) (step S403). When the compression sort page number (x) and the transfer sort page number (i) match, the total transfer time is better when only the compression process is executed than when the raw data page is transferred in parallel with the compression process. Indicates that becomes shorter. Therefore, when the compression sort page number (x) matches the transfer sort page number (i) (step S403; Y), only the xth page is compressed (step S404). When "x" does not match "i" (step S403; N), raw data transfer of the i-th page and compression processing of the x-th page are performed in parallel (step S405).

When the transfer of the raw data of the i-th page is completed, the CPU 31 determines whether or not the compression process of the x-th page is completed (step S406). If the compression processing of the x-th page is not yet completed when the transfer of the raw data of the i-th page is completed (step S40).
6; N), the raw data is sequentially transferred page by page from the smallest data amount until the compression processing of the x-th page is completed (step S407). After transferring the raw data until the compression processing of the x-th page is completed, the CPU 31 compares the data size of the compressed data of the x-th page with the data size of the raw data of one page before compression ( Step S408). When the data size after compression is larger than that before compression (step S408; Y),
The order information of the page is added to the raw data of page x before compression and the raw data is transferred (step S409).

If the data size after compression is not larger than that before compression (step S408; N), the page order information of the page x is added to the compressed data of page x and the data is transferred to the printer 12 (step S410). . Then the CPU
31 updates the transfer sort page number (i) to a value obtained by subtracting “1”. Also, the compression sort page number (x)
Is incremented by "1" (step S411). Whether twice the time required for the previous compression is shorter than the transfer time of the raw data for one page, that is, whether the relationship of 2a <cd shown in the equation (2) is established. Check (step S412). If twice the compression time is shorter (step S412; Y), the compression sort page number (x) is changed to the same value as the transfer sort page number (i) (step S413).

When twice the compression time is not shorter than the transfer time of the raw data (step S412; N), or after changing the value of "x" to the same value as "i" in step S413, the CPU 31 It is determined whether or not the compressed sort page number (x) exists in the remaining pages to be transferred (step S414). If it does not exist in the remaining pages (step S414; N), step S40
Returning to step 3, transfer processing of the remaining pages is continued. When there is no page to be compressed among the remaining pages (step S414; Y), all the remaining pages are transferred as raw data (step S415), and the process ends (end). As described above, since the compression processing is performed by giving priority to the data having a large amount of data, it is possible to effectively reduce the transfer time by the compression.

Also in the first to third modifications, when the relation of the expression (2) is established, the compression and the raw data transfer are not performed in parallel, but only the compression process is performed. As a result, as described in the embodiment, the transfer time is not longer than that when only the compression process is performed, and the transfer time can be surely shortened.

In the embodiment and the modification described above, there is no compression processing time (a) to be used as a reference until the compression processing of the first page is completed. Therefore, when starting the transfer, the transfer of the raw data and the compression process are always performed in parallel. In this case, as shown in FIG. 5, after the transfer of the first page is completed, the compression of the second page may not be completed yet, and a waiting time may occur until the compression is completed. Therefore, in order to transfer the first page more efficiently, the average compression time required to transfer the print data of the previous document may be used as the initial value of the compression processing time (a). .

That is, in the case of the embodiment in which the transfer is performed without breaking the page order, the page number to be compressed first is obtained based on the previous average compression time. Further, in the embodiment and the modified examples, it is checked whether twice the average compression time of the previous time is shorter than the transfer time of raw data, and the compression process and the transfer of raw data should be performed in parallel for the first page. Try to determine whether.

Further, in the embodiment and the modification, the raw data transfer or compression processing is performed in units of one page, but these units may not be in units of pages. 1
The page may be transferred or compressed in units of blocks obtained by dividing the page. Further, a plurality of pages may be treated as one block. When image data and code data are mixed in one page, the print data may be divided at the boundary between them and transferred or compressed.

[0075]

As described above, according to the first aspect of the present invention, the uncompressed print data is transferred in parallel with the compression process, and the compressed print data is transferred after the compression process is completed. The total time required to transfer print data can be shortened.

According to the second aspect of the invention, since the compression process is performed in parallel with the transfer of the uncompressed print data, the total time required for the transfer of the print data can be shortened. Also, since the print data in the order that should be transferred next to the print data that is transferred without being compressed is compressed,
The print data can be transferred without breaking the order.

Further, according to the third aspect of the invention, the print data is divided into predetermined print areas and the order information indicating the print order is added to them, so that the print data can be transferred in an arbitrary order. You can This eliminates the need for a process of determining the transfer amount for one transfer or the position of the print data to be compressed in parallel with the transfer in order not to disturb the transfer order, and the configuration of the print data transfer device can be simplified.

According to the fourth aspect of the present invention, the print data in the predetermined format is preferentially compressed, and in parallel with this, the print data other than the predetermined format is transferred. For example,
If the page represented by the raster data is compressed in parallel with the transfer of the page represented by the code data such as the character code, the transfer time can be shortened efficiently.

Further, according to the invention described in claim 5, the data having a large amount of data is preferentially compressed, and in parallel with this, the data having a small amount of data is preferentially transferred without being compressed. . Usually, the larger the amount of data, the longer the compression process takes. Therefore, if the print data with a large amount of data and a small amount of data is transferred in parallel with the compression, the ratio of the period during which the transfer and the compression are performed in parallel. Can be increased and the transfer efficiency can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an outline of a configuration of a printing system using a print data transfer device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing an outline of a circuit configuration of the print data transfer apparatus shown in FIG.

FIG. 3 is a flowchart showing a flow of processing performed by the print data transfer apparatus.

FIG. 4 is an explanatory diagram showing an example of a raw data transfer time, a compression time, and a time for transferring compressed data.

FIG. 5 is an explanatory diagram schematically showing how print data is transferred.

FIG. 6 is a flowchart showing a flow of processing performed by a print data transfer apparatus in the first modified example.

FIG. 7 is a flowchart showing a flow of processing performed by a print data transfer device in a second modified example.

FIG. 8 is a flowchart showing a flow of processing performed by a print data transfer apparatus in a third modified example.

[Explanation of symbols]

11 ... Print data transfer device, 12 ... Printing device, 13 ... Transfer source buffer memory, 14 ... Transfer circuit, 15, 36 ... Compression circuit, 16 ... Compression buffer memory, 17 ... Compression time measurement circuit, 18 ... Compression time estimation circuit , 19 ... Compression / transfer instruction circuit, 31 ... CPU, 32 ... Bus, 33 ... ROM, 3
4 ... RAM, 35 ... Buffer memory, 37 ... DMA controller, 38 ... Transfer control circuit

Claims (5)

[Claims] 1. A print data storage unit for storing print data, a compression unit for compressing print data corresponding to a first print area in the print data stored in the print data storage unit, and the compression unit. Is compressing the print data corresponding to the first print area, in parallel with this, the print data of the second print area as another area is transferred to a predetermined transfer destination without the compression means. Compressed when the transfer of the print data of the first print area by the first transfer means and the compression of the print data of the second print area by the compression means are completed. And a second transfer unit for transferring the print data of the second print area after the transfer to the predetermined transfer destination. 2. A print data storage means for storing print data, and a quantity of print data corresponding to a print area of a predetermined fixed size among the print data stored in the print data storage means. Of the print data accumulated in the print data accumulating unit, and a predetermined transfer destination for the amount of print data that can be transferred during the time obtained by the compression time acquiring unit. A first transfer means for transferring the print data to the print data storage means without compressing the print data, and a first transfer means for transferring the print data while the first transfer means transfers the print data. A compression unit that compresses an amount of print data corresponding to the print area of a predetermined size to be transferred next to the print data that is currently transferred by one transfer unit; When the transfer means operates alternately and the compression of the print data by the compression means and the transfer of the print data by the first transfer means are completed, the print data compressed this time by the compression means is transferred to the predetermined transfer destination. A print data transfer apparatus comprising: a second transfer unit. 3. A print data storage unit for storing print data, and the print data stored in the print data storage unit is divided into unit print data for each amount corresponding to a print area of a predetermined size. Order information adding means for adding order information indicating the order of printing, and a first one for transferring any one of the unit print data to which the order information is added by the order information adding means to a predetermined transfer destination. And a compression unit that compresses another arbitrary unit print data from the time when the first transfer unit starts the transfer of the arbitrary unit print data, and the first transfer unit. When the transfer of one unit print data is completed and the compression of the other one unit print data by the compression means is not completed, either compression or transfer is not yet performed. 1 Continuous transfer instructing means for instructing the first transfer means to transfer the unit print data, and when the first transfer means completes the transfer of one unit print data, the other one by the compression means A second transfer means for transferring the other one unit print data after being compressed when the compression of the unit print data is completed, to a predetermined transfer destination. apparatus. 4. A print data storage unit for storing print data, and the print data stored in the print data storage unit is divided into unit print data for each amount corresponding to a print area of a predetermined size. Order information adding means for adding order information indicating the order of printing, and data format determination for determining whether each unit print data to which the order information is added by the order information adding means has a predetermined data format Means, a first transfer means for transferring any one unit print data which is determined not to be the predetermined format by the data format determination means to a predetermined transfer destination, and the first transfer means is for the arbitrary transfer means. A compression unit that compresses another unit print data that is determined to have the predetermined format from the time when the transfer of one unit print data is started; When the compression unit has not finished compressing the other unit print data that has been determined to have the predetermined format at the time when the transfer of the unit print data is completed, the unit print data that is not in the predetermined format is not yet processed. Continuous transfer instruction means for instructing the first transfer means to transfer any one unit print data that has not been transferred; and the compression when the first transfer means completes the transfer of one unit print data. A second means for transferring the other one unit print data after being compressed to a predetermined transfer destination when the means finishes compressing the other one unit print data determined to be the predetermined format; And a print data transfer device. 5. A print data storage unit for storing print data, and the print data stored in the print data storage unit is divided into unit print data for each amount corresponding to a print area of a predetermined size. Order information adding means for adding order information indicating the order to be printed, data amount calculating means for calculating the data amount of each unit print data to which the order information is added by the order information adding means, and this data amount calculation First selecting means for selecting one unit print data to be transferred next in the ascending order of the data amount obtained by the means; and one unit for compressing next in the descending order of the data amount obtained by the data amount calculating means. Second to select print data
Selection unit, a first transfer unit that transfers one unit print data selected by the first selection unit to a predetermined transfer destination, and the first transfer unit starts transfer of the unit print data. From time to time, a compression unit that compresses one unit print data selected by the second selection unit, and a compression unit that compresses the unit print data when the first transfer unit finishes transferring one unit print data. When the compression of one unit print data selected by the second selecting unit is not completed, the unit selecting unit selects the unit print data having the next smallest data amount by the first selecting unit. Continuous transfer instructing means for transferring to a predetermined transfer destination by the compression means, and the compression means selected by the second selection means when the first transfer means finishes transferring one unit print data. And a second transfer means for transferring the compressed unit print data to the predetermined transfer destination when the compression of the compressed unit print data is completed. .