JP3355909B2 - Printer control method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printer control method and apparatus, and more particularly, to a printer control method and apparatus for compressing uncompressed data, storing the compressed data in a memory, reading it out again, decompressing it, and outputting it to a printer. About.

[0002]

2. Description of the Related Art In a case where a plurality of originals are sequentially read and each page is copied by a required number of copies, conventionally, the same original is repeatedly read for the required number of copies, but in recent years, for example, Japanese Patent Publication No. 7-53454. As described in the official gazette, a plurality of originals are read one by one in order and stored in an image memory, and the stored image data is repeatedly read out from the memory in order to copy the required number of copies once. 2. Description of the Related Art A printer device that can be performed only by reading a document has been widely used.

However, since image data has a large amount of information, storing a plurality of page images requires an enormous memory capacity. For this reason, for example, in JP-A-1-209169, a compressor for compressing image data and a decompressor for expanding the image data are provided, and the image data to be stored in the memory is compressed in advance by the compressor to reduce the storage capacity. On the other hand, there has been proposed a page printer print control device in which compressed data read from a memory is restored to original image data by a decompressor and then output to a printer.

In such a configuration, a first storage area for temporarily storing uncompressed bitmap data and a second storage area for storing compressed data obtained by compressing the uncompressed data by a compression device. Required. Further, even if compression is performed by the compression device, the capacity does not always decrease, and the capacity of compressed data may exceed the capacity of non-compressed data depending on the pattern of bitmap data.

On the other hand, the worst value of the compression ratio (compressed data / uncompressed data) when the capacity of the compressed data exceeds the capacity of the uncompressed data is predetermined for each compression method. For example, in the “LZ77” system, The worst compression ratio is 9 /
8 is guaranteed.

Accordingly, when the capacity of the uncompressed data is D, (1 + 9/8) D is indispensable as the storage capacity for the first and second storage areas.

[0007]

In the above-mentioned prior art, the total capacity of the storage capacity required for the first storage area and the storage capacity required for the second storage area is equal to the memory capacity required for the image memory. There is a problem that a large memory capacity is required because of the large capacity.

An object of the present invention is to provide a printer control method and apparatus which solves the above-mentioned problems of the prior art and which can reduce the memory capacity required when compressing and storing uncompressed bitmap data. To provide.

[0009]

Means for Solving the Problems In order to achieve the above object, the present invention is characterized in that the following means are taken. (1) storage means for storing uncompressed data for each unit amount,
An uncompressed data reading means for sequentially reading the uncompressed data from the storage means, a compression means for compressing the read uncompressed data, and a compressed data writing means for writing the compressed data to the storage means. (2) The compressed data writing means writes the compressed data into a substantially free area of the storage means from which the uncompressed data has already been read. (3) When the practical free space is insufficient, the non-compressed data saving means for saving the non-compressed data of the area to which the non-compressed data is to be written to the free area of the storage means to secure a substantial free area. Was further provided. (4) The read start position by the non-compressed data read means and the write start position by the compressed data write means are made the same. (5) When the capacity Mmax is guaranteed as the upper limit of the capacity of the compressed data obtained by compressing a unit amount of uncompressed data by the compression means, the storage means stores the capacity M expressed by the following equation.
It was made to have.

Mmax ≦ M <(Mmax + unit amount) (6) In a printer control method for compressing and storing uncompressed data, reading it out again, decompressing it and outputting it to the printer, the data is stored in the storage means. Uncompressed data is sequentially read and compressed, and the compressed data is stored in the storage unit.
Uncompressed data before reading is written so as not to be destroyed.

According to the above configuration (1), the data read from the storage means and compressed is stored again in the same storage means, so that the uncompressed data and the compressed data can share the storage area. Become.

According to the above configuration (2), the ratio of the storage area shared by the uncompressed data and the compressed data increases.

According to the above configuration (3), when the compressed data is about to be overwritten on the uncompressed data which has not been processed yet, the uncompressed data is evacuated to a free area. Data destruction is prevented.

According to the above configuration (4), data write control and data read control are simplified.

According to the above configuration (5), an optimum value according to the compression method can be selected as the capacity of the storage means.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 2 is a functional block diagram of the printer control device of the present invention. The uncompressed data writing unit 20 stores the uncompressed data in the storage unit 10 as uncompressed data D for each first unit amount (for example, for one page). The uncompressed data reading means 30 sequentially reads the uncompressed data D from the storage means 10 as uncompressed data Dx for each second unit amount smaller than the first unit amount. Compression means 40
Generates compressed data dx by sequentially compressing the read uncompressed data Dx. The compressed data writing means 50 converts the compressed data dx into the uncompressed data Dx so as not to destroy the uncompressed data D in the storage means 10 before reading.
x is a vacant area of the storage means 10 from which x has been read
(Expressed as an empty area after reading). The uncompressed data saving means 60 saves the uncompressed data Dx stored in the area where the compressed data dx is to be written to the free area on the storage means 10 when the free space after reading on the storage means 10 becomes insufficient. In this way, a free area (hereinafter, referred to as a saved free area) is secured.

In such a configuration, when the uncompressed data D is stored in the storage means 10 by the uncompressed data writing means 20, the uncompressed data reading means 30
From the uncompressed data D by a second unit amount
The data is sequentially read out as x and transferred to the compression means 40. The storage area from which the uncompressed data Dx has been read will be treated as a post-read free area thereafter. The compression means 40 compresses the transferred uncompressed data Dx and transfers it to the compressed data writing means 50 as compressed data dx. The compressed data writing means 50 sequentially stores the compressed data dx in a storage area in the storage means 10 from which the uncompressed data Dx has been read out and which has newly become a free area after reading.

Here, if the capacity of the compressed data dx exceeds the capacity of the uncompressed data Dx due to the low compression ratio of the uncompressed data Dx, the free space after reading after the uncompressed data Dx is read out. The compressed data dx cannot be stored in the area. If this is left as it is, the compressed data dx is overwritten on the uncompressed data D before reading, and the uncompressed data D is destroyed. As described above, when the free area of the storage means 10 becomes insufficient after reading, the non-compressed data saving means 60 stores the non-compressed data Dx stored in the area where the compressed data dx is to be written on the storage means 10. To a free area, and secure a free area after the save.

As described above, according to the present invention, the non-compressed data read from the storage means is stored again in the free space after reading (or the free space after saving) after the non-compressed data is read after compression. As a result, the storage area is shared between the uncompressed data and the compressed data, and the capacity of the storage unit can be reduced.

FIG. 1 is a block diagram of a printer control device 1 according to an embodiment of the present invention. The printer control device 1 of the present invention is connected to a plurality of computers 3 via a network 2 such as a local area network (LAN), and each computer 3 transmits print data to the printer control device 1 as a host device. Upon receiving the print data, the printer control device 1 performs appropriate data processing and sends the data to the printer 4.

The CPU 102 of the printer control device 1 includes the uncompressed data writing means 20, the uncompressed data reading means 30, and the compressed data writing means 5 described with reference to FIG.
0, and controls the operation of the entire printer control device 1 according to a program, constants, and the like stored in the program memory 103 in advance. A communication interface (I / F) 101 controls transmission and reception of data with the computer 3 via the network 2. The working memory 104 stores data temporarily used for control of the printer control device 1.

The compression / expansion unit 107 functions as the compression means 40 and performs compression processing on bitmap data temporarily stored in the image memory 109 and expansion processing on compressed data stored in the hard disk device 108 according to the LZ77 system. The algorithm is executed according to the following algorithm. The image memory 109 functions as the storage unit 10 and has a storage capacity of 4.8 MB (megabyte) in the present embodiment. The storage capacity of the image memory 109 is LZ77 in 4 MB which is the data amount of print data for one page.
It is necessary to exceed 4.5 MB multiplied by the worst compression ratio of 9/8 in the system, but any value may be used as long as it is less than (4 + 4.5) MB. The image transfer I / F 110 is connected to the printer 4
The print data read from the image memory 109 is transferred to the printer 4 in synchronization with a synchronization signal output from the printer 4.

Hereinafter, the operation of the present embodiment will be described with reference to the flowcharts of FIGS. In step S1, when the print data transmitted from the computer 3 is received via the network 2 and the communication I / F 101, the received print data is stored in the hard disk device (HDD) 108 in step S2. If it is determined in step S3 that all the print data has been received and stored, the process proceeds to step S4 to print the print data.

In step S4, the hard disk drive 1
The print data is read from 08 in page units, and is developed into bitmap data on the image memory 109. In step S5, as will be described in detail later, the image memory 109
The bitmap data is sequentially read from above and transferred to the compression / expansion unit 107, and after being compressed by the compression / expansion unit 107, is stored again in the image memory 109.

Here, the processing of step S5 will be described in more detail with reference to the flowchart of FIG. In step S501, the head address of the bitmap data stored in the image memory 109 is specified as the read address RAD.
Is designated as the write address WAD.
In this embodiment, as shown by hatching in FIG. 5A, 4 MB of bitmap data is stored from the start address AD0 to AD10 of the image memory 109, and 0.8 MB of the addresses AD10 to AD12 is a free area. The description will be continued. Therefore, step S5
In 01 and S502, the start address AD0 is designated as both the read address RAD and the write address WAD. As described above, when the read address RAD of the bitmap data is the same as the write address WAD of the compressed data, the data write control and the read control are simplified.

In step S503, the image memory 109
From the specified read address RAD (AD0), bitmap data is stored in a predetermined unit amount (actually, about 4 KB is preferable, but in the present embodiment, in order to make the drawing easy to see, 0.4 MB for one address). 0.4 MB buffer 104 read and secured in working memory 104
a is temporarily stored. Therefore, at this time, the address A is stored in the image memory 109 as shown in FIG.
An empty area after reading of 0.4 MB is secured in D0 to AD1.

In step S504, the specified write address WAD (AD0) is stored in the bitmap data storage area (at this point, the bitmap data has not been read yet).
It is determined whether or not the addresses AD1 to AD10 in FIG. 5B are specified, that is, whether or not the compressed data is about to be overwritten on the bitmap data that has not been read. At first, since the start address (address AD0) of the empty area after reading in which the reading of the bitmap data has already been completed is specified, it is determined that it is not overwriting, and step S5 is performed.
Go to 05.

In step S505, the buffer 10
The bitmap data in 4a is sequentially encoded and compressed by the compression / expansion unit 107. In step S506, the compressed data is stored in the image memory 109 in order from the write address WAD (AD0) designated in step S502.
In step S507, it is determined whether or not the compression processing of all the bitmap data in the buffer 104a has been completed. If the compression processing has not been completed, the process returns to step S504, and the processing is repeated. S5
Proceed to 08.

FIG. 5C shows an example of the contents stored in the image memory 109 at the time when the compression processing of all the bitmap data in the buffer 104a has been completed. Since the data amount of the compressed data is smaller than the data amount of the bitmap data (0.4 MB), an empty area remains.

In step S508, the image memory 109
It is determined whether or not the compression processing for the bitmap data for one page stored in is completed. At first, it is determined that the processing has not been completed, and the process proceeds to step S509. In step S509, the image memory 1 is set as the write address WAD.
09, the start address of the empty area after reading is designated. In step S510, it is determined whether there is any data being saved, which will be described later. Since there is no saved data at first, the process proceeds to step S511. In step S511, the next address on the image memory 109 (that is, AD1) is specified as the read address RAD, and then the process returns to step S503.

In step S503, one bit of the remaining bitmap data (0.4 MB of addresses AD1 to AD2) is read from the read address RAD (AD1) designated in step S511. Is temporarily stored in the buffer 104a. Step S
In steps 504 to S507, the buffer 104a
Are sequentially compressed, and are sequentially stored again in the empty area after readout of the image memory 109.

Here, although the compression ratio of the bitmap data is reduced and the unprocessed bitmap data remains in the buffer 104a, the address AD2 of the image memory 109 as shown in FIG. If the compressed data is filled up and the free area becomes insufficient after reading, step S504
Then, it is determined that data is about to be written on bit map data for which reading has not been completed, and the process proceeds to step S513. In step S513, the area where the compressed data is about to be overwritten (address AD2
As shown in FIG. 5 (e), the bit map data of AD3) is the address A which is a free area on the image memory 109.
The data is saved after D11, and in steps S505 and S506, the remaining compressed data is stored in the free space after saving (addresses AD2 to AD3) generated by the saving. FIG. 5F shows the storage contents of the image memory 109 when the storage of the remaining compressed data is completed.

Thereafter, when the process proceeds to step S510, it is determined that the bitmap data saved in step S513 exists, and the process proceeds to step S512.
Proceed to. In step S512, the head address AD11 of the saved bitmap data is specified as the read address RAD. Therefore, in the next step S503, the saved bitmap data is preferentially read and stored in the buffer 104a.

As described above, the compression processing of the bitmap data for one page stored in the image memory 109 is completed, and the fact that the compressed data for one page has been stored in the image memory 109 is determined in step S508. When detected,
The process proceeds to step S6 in FIG.

In step S6, one page of compressed data newly stored in the image memory 109 is stored in the hard disk device 108. In step S7, it is determined whether or not the processing for all pages has been completed. If not, the flow returns to step S4 to store the bitmap data of the next page from the hard disk device 108 into the image memory 10
9, and the above processing is repeated. When the processing for all pages is completed, the compressed data is read out one page at a time from the hard disk device 108 in step S8, and the read compressed data is Is transferred to the printer 4.

As described above, according to the present embodiment, the data read and compressed from the image memory is stored again in the same image memory, so that the bitmap data and the compressed data share the memory. And the memory capacity can be reduced.

Further, when the compressed data is about to be overwritten on bitmap data that has not been processed yet,
Since the bitmap data is saved in the empty area, data destruction is prevented even in a case where the compression rate is reduced and the data amount of the compressed data exceeds the data amount of the bitmap data. .

[0038]

As described above, according to the present invention, the following effects can be achieved. (1) According to the first and sixth aspects, since the data read and compressed from the storage means is stored again in the same storage means, the storage area can be shared between the uncompressed data and the compressed data. Thus, the capacity of the storage means can be reduced. (2) According to the second aspect, since the compressed data is written in the free area after the reading of the storage means from which the non-compressed data has already been read, the storage area shared by the non-compressed data and the compressed data is stored. As the ratio increases, the capacity of the storage means can be further reduced. (3) According to the third aspect, when the compressed data is about to be overwritten on the uncompressed data which has not been processed yet in the storage means, the uncompressed data is evacuated to a free area. And the data amount of the compressed data exceeds the data amount of the uncompressed data, thereby preventing data destruction. (4) According to the fourth aspect, data write control and data read control are simplified. (5) According to the fifth aspect, it is possible to select an optimum value according to the compression method as the capacity of the storage means.

[Brief description of the drawings]

FIG. 1 is a block diagram of one embodiment of the present invention.

FIG. 2 is a functional block diagram of the present invention.

FIG. 3 is a flowchart showing the operation of the present invention.

FIG. 4 is a flowchart showing the operation of the present invention.

FIG. 5 is a diagram schematically illustrating the storage contents of an image memory.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Printer control device, 2 ... Network, 3 ... Computer, 4 ... Printer, 10 ... Storage means, 20 ... Uncompressed data writing means, 30 ... Uncompressed data reading means, 40 ...
Compression means, 50: compressed data writing means, 60: non-compressed data saving means

Continuation of the front page (51) Int.Cl. ⁷ identification code FI H04N 1/21 H04N 1/21 1/41 1/41 Z (58) Investigated field (Int.Cl. ⁷ , DB name) B41J 5/30 G06F 3/12 G06F 12/00 580 G06F 12/02 530 H04N 1/21 H04N 1/41

Claims (3)

(57) [Claims] 1. A printer control device for compressing and accumulating uncompressed data, reading the compressed data again, decompressing the compressed data, and outputting the decompressed data to a printer device. An uncompressed data reading means for sequentially reading uncompressed data from the memory; a compression means for compressing the read uncompressed data; and a compressed data writing means for writing the compressed data to the storage means. 2. The printer control device according to claim 1, wherein the writing unit writes the compressed data into a vacant area after reading from which uncompressed data has already been read. 2. The non-compressed data for saving the free area after saving by saving the uncompressed data of the area where the compressed data is to be written to another free area of the storage means when the free area after reading is insufficient. 2. The printer control device according to claim 1, further comprising a save unit, wherein the compressed data is written in the free space after the save . 3. The printer control device according to claim 1, wherein a read start position of the uncompressed data read unit and a write start position of the compressed data write unit are the same.