JP3674644B2 - Data generator for printing - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a print data generation apparatus that compresses and accumulates image data, reads it out again, decompresses it, restores it to the original image data, and outputs it. Then, the present invention relates to a print data generating apparatus which outputs a page image by inverting the top, bottom, left and right.
[0002]
[Prior art]
In the case where a plurality of originals are sequentially read and each page is copied for each required number of pages, the same original has been repeatedly read for the required number of copies. However, in recent years, for example, it is described in Japanese Patent Publication No. 7-53454. As described above, a plurality of originals are read one by one in order and stored in the image memory, and the stored image data is repeatedly read out from the memory in order, so that the required number of copy outputs can be obtained by a single reading operation. Devices that can be used are widespread.
[0003]
However, since image data has a large amount of information, an attempt to store a plurality of page images results in an enormous memory capacity. Therefore, in general, a compressor for compressing image data and a decompressor for expanding the image data are provided, and the image data stored in the memory is pre-compressed by the compressor to reduce the storage capacity, while the compressed data read from the memory Is restored to the original image data by the decompressor and then output to the printing unit or the like.
[0004]
On the other hand, in an apparatus capable of double-sided printing, as discussed in, for example, Japanese Patent Laid-Open No. 60-204379, all the image data of the back page is reversed upside down, left and right, that is, the image data is rotated 180 °. It is necessary to output to the printing part. Regarding the image data rotation method, the following two methods have been proposed so far.
[0005]
The first method is a method in which input image data is first rotated by 180 °, and is compressed and stored in a memory. The second method is not rotated when compressed and stored. In this method, image data for one page is read and expanded, and then rotated by 180 °.
[0006]
[Problems to be solved by the invention]
In the first method described above, the image data stored in the memory intended to perform double-sided printing is rotated by 180 ° for each page. If for some reason it becomes necessary to print on one side, There is a problem that the document must be read, compressed, and stored again.
[0007]
In the second method described above, the image data is rotated 180 ° after the image data is read out, so there is no problem with the first method, but the expanded image data for one page is rotated 180 °. There is a problem that the memory capacity increases because a separate storage area is required.
[0008]
SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art and provide a printing data generator capable of rotating image data even after storing compressed data without greatly increasing the memory capacity. There is.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, in the present invention, compression means for compressing image data for each predetermined unit block, storage means for storing compressed image data for each unit block, and front side printing or back side printing In response to the instruction, the first reading means for reading the accumulated image data for each unit block from the forward or reverse direction, the decompression means for decompressing the read image data for each unit block, A data buffer for storing the image data for the expanded unit block; and second reading means for reading the image data on the data buffer from the forward and reverse directions in response to an instruction for front side printing or back side printing, respectively It is characterized by having
[0010]
According to the above-described configuration, the reading direction of each unit block and the reading direction of the byte data constituting each unit block are opposite to those at the normal time at the back surface printing timing, and the image data is substantially rotated by 180 °. The image data can be rotated even after the compressed data is accumulated without increasing the memory capacity.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram of an embodiment of a printer control apparatus to which a printing data generator of the present invention is applied. The network interface circuit 6 transmits / receives print data and its attribute data to / from an operator (user). A user interface (hereinafter referred to as UI) control circuit 9 receives a print command from an operator and provides print information to the operator. The system memory 3 is used as a program area and an image memory area of the system. The hard disk device 4 stores a plurality of pages of image data (uncompressed data) and compressed image data (compressed data).
[0012]
The compression / decompression circuit 7 performs compression by encoding image data and expansion by decoding compressed data. The communication control circuit 8 controls the operation of the printer 5. The output circuit 10 outputs the image data stored for each unit amount in its own data buffer in synchronization with the printing timing of the printer 5. The main processor 1 develops a dot image on the system memory 3 according to print information transferred from the network interface circuit 6, that is, a page description language (hereinafter referred to as PDL), the number of copies, a print surface (one side or both sides), and the like. Is stored in the hard disk device 4 after being compressed.
[0013]
FIG. 2 is a functional block diagram of the present invention and a schematic representation of the operation during front side printing and back side printing. The compression means 7a is a function of the compression / decompression circuit 7, and encodes and compresses one page of bitmap data D read from the system memory 3 for each of a plurality of unit blocks D1, D2,. Output as compressed data d1, d2,. The storage means 4a is a function of the hard disk device 4 and stores the compressed data d1, d2,.
[0014]
The first reading means 7c is a function of the compression / decompression circuit 7, and the compressed data d1 to dm stored in the storage means 4a are subjected to surface printing and printing separately designated by an instruction from the main processor 1 or the like. In response to any of the instructions for printing on the back side, the data is read out from the forward side, ie, the compressed data d1 side, or from the opposite side, ie, the compressed data dm side, by DMA transfer and output to the decompressing means 7b in this order.
[0015]
The decompression means 7b is also a function of the compression / decompression circuit 7, and the compressed data d1 to dm are decoded by decompressing the compressed data dx sequentially read by the first reading means 7c in this order. Are restored to the unit blocks D1 to Dm, respectively. The data buffer 10a is a function of the output circuit 10, and temporarily stores the unit blocks D1 to Dm restored by the decompression means 7b one block at a time.
[0016]
The second reading means 10b is also a function of the output circuit 10, and each of the data b1, b2,... Bn constituting each unit block Dx sequentially stored in the data buffer 10a is separately designated for surface printing and In response to any of the instructions for printing on the back side, the data are sequentially read out in the forward direction (for example, from the data b1 on the left side in the figure) or in the reverse direction (for example, from the data bn on the right side in the figure), respectively. Output in order. The printing unit 5a is a function of the printer 5 and prints and outputs each data bx (b1 to bn or bn to b1) sequentially read by the second reading means 10b. As a result, normal image data is printed out at the front side printing timing in the single-sided printing mode and double-sided printing mode, and image data rotated by 180 ° is printed out at the back side printing timing in the double-sided printing mode.
[0017]
Hereinafter, the operation of this embodiment will be described in detail. FIG. 3 is a flowchart showing the operation of the present invention. In step S 1, the first page of the bitmap data for a plurality of pages is developed on the system memory 3. In step S2, bitmap data D for one page temporarily stored in the system memory 3 is encoded and compressed for each unit block D1, D2... Dm by the compression means 7a, and stored as compressed data d1, d2. Accumulated in 4a. In step S3, it is determined whether or not the compression and accumulation of the bitmap data for one page has been completed. When the encoding compression and accumulation for all the unit blocks D1 to Dm are completed, the process proceeds to step S4.
[0018]
FIG. 4 is a diagram schematically showing the data structure of the compressed data sequence for one page stored in the storage means 4a. Here, the compression for each unit block of the bitmap data D is performed in units of lines. An example is shown. That is, the compressed data d1, d2,... Dm in FIG. 2 correspond to the first, second, and m-th line compressed data in FIG.
[0019]
A “final line offset address” is added to the head of the compressed data string as an offset value indicating the final address of the data string, and then the compressed data for each line is connected. In addition, a byte count (data size) of the compressed data is added to both ends of each compressed data. However, for the last m-th line compressed data, the byte count is added only at the leading end and not at the trailing end.
[0020]
Returning to the flowchart of FIG. 3 again, in step S4, it is determined whether the printing mode is the single-sided printing mode or the double-sided printing mode. If the single-sided printing mode is instructed, the process proceeds to step S6 and the double-sided printing mode is designated. If so, the process proceeds to step S5. In step S5, it is further determined whether it is the front surface printing timing or the back surface printing timing in the double-sided printing mode. If it is the front surface printing timing, the process proceeds to step S6 as in the single-sided printing mode, and at the backside printing timing. If there is, the process proceeds to step S7.
[0021]
In step S6, as shown in FIG. 5, the first reading means 7c performs DMA transfer of the m first to m line compressed data stored in the storage means 4a from the positive side, that is, the first line compressed data side. Are sequentially read out and transferred to the decompression means 7b in this order. On the other hand, in the backside printing step S7, as shown in FIG. 6, the first reading means 7c transfers the m first to m-line compressed data from the reverse side, that is, the m-th line compressed data side by DMA transfer. Read sequentially, and transfer to the decompression means 7b in this order.
[0022]
The reading from the opposite side can be performed at high speed and reliably by referring to the “byte count” added to the rear end of each compressed data described with reference to FIG. For example, when the processing related to the m-th line compressed data of the last line is completed, the “byte count” added before the “byte count” added immediately before the m-th line compressed data is read. Since the “byte count” represents the data amount of the (m−1) th line compressed data, the address returned by the “byte count” from the current position is the (m−1) th line compressed to be processed next. This is the start address of the data.
[0023]
Each compressed data read out as described above is decompressed for each unit block in step S8 and stored in the data buffer 10a. In step S9, it is determined again whether the printing mode is the single-sided printing mode or the double-sided printing mode. If the printing mode is the single-sided printing mode, the process proceeds to step S11. If the printing mode is the double-sided printing mode, the process proceeds to step S10. In step S10, it is further determined whether it is the front surface printing timing or the back surface printing timing in the double-sided printing mode. If it is the front surface printing timing, the process proceeds to step S11 as in the single-sided printing mode. If there is, the process proceeds to step S11.
[0024]
In step S11, as shown in FIG. 8, the second reading means 10b converts the n pieces of byte data 1 to n constituting the compressed data for one line stored in the data buffer 10a to the positive side, that is, byte data. The data are sequentially read from the 1 side and transferred in the order. On the other hand, in step S12 for reverse side printing, as shown in FIG. 9, the second reading means 10b sequentially reads the byte data 1 to n from the reverse side, that is, the byte data n side, and transfers them in this order. The transferred byte data 1 to n (or byte data n to 1) is printed out in step S13.
[0025]
FIG. 7 is a block diagram showing the configuration of the output circuit 10 provided with the second reading means 10b. In the block diagram of FIG. 7, the processes of the steps S11 and S12 are executed as follows. .
[0026]
The unit block number m is registered in the line counter 102 of the output circuit 10, and the byte data number n is registered in the dot counter 103. The count value of the line counter 102 is decreased in synchronization with the vertical synchronization signal output from the printer 5. Therefore, when the processing for one page is completed, the count value of the line counter 102 becomes “0”. Further, the count value of the dot counter 103 is decreased in synchronization with the horizontal synchronizing signal output from the printer 5. Therefore, when the processing for one line is completed, the count value of the dot counter 103 becomes “0”. When the count value of the dot counter 103 becomes “0”, the read control circuit 104 stops outputting the busy signal and prepares for the next data input.
[0027]
The address counter 101 is instructed to count up at the front surface printing timing in the single-sided printing mode and the double-sided printing mode, and is set to an initial value “0”. On the contrary, at the back side printing timing in the duplex printing mode, down count is instructed and the initial value “n” of the dot counter 103 is set as the initial value. The address counter 101 counts up or down in synchronization with the read timing signal output from the read control circuit 104. Since the data buffer 10a outputs byte data at the address indicated by the count value of the address counter 101, selective reading from the forward direction or the reverse direction as described above becomes possible.
[0028]
When the final data is shorter than the data width of the data buffer 10a, the output bit number conversion circuit 10c switches the number of bits by switching the output of the most significant bit and the output of the least significant bit.
[0029]
Returning to the flowchart of FIG. 3 again, when the print output for one line is completed in step S13, it is determined in step S14 whether the print output for all lines, that is, the print output for one page has been completed. If not, the process returns to step S4 to repeat the above processes. When printing for one page has been completed, the presence / absence of the next page is determined in step S15, and if there is a next page, the process returns to step S1 and the processes described above are executed for the next page. .
[0030]
【The invention's effect】
As described above, according to the present invention, the bitmap data is compressed and stored for each unit block, and the reading order of each unit block and the reading order of the byte data constituting each unit block are printed on the single-sided printing mode. Mode and double-sided printing mode, and if it is double-sided printing mode, depending on whether it is front side printing timing or back side printing timing, image data without increasing the memory capacity Can be rotated even after the compressed data is accumulated.
[Brief description of the drawings]
FIG. 1 is a block diagram of an embodiment of a printer control apparatus to which a printing data generation apparatus of the present invention is applied.
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 diagram illustrating a data structure of compressed data for one page.
FIG. 5 is a diagram showing a method for reading compressed data for a surface.
FIG. 6 is a diagram showing a method for reading back-side compressed data.
7 is a block diagram showing a configuration of the output circuit 10. FIG.
FIG. 8 is a diagram showing a data reading method for each surface line.
FIG. 9 is a diagram illustrating a data reading method for each line for the back surface.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Main processor, 3 ... System memory, 4 ... Hard disk apparatus, 4a ... Storage means, 5 ... Printer, 6 ... Network interface circuit, 7 ... Compression / decompression circuit, 7a ... Compression means, 7b ... Expansion means, 7c ... 1st 1 reading means, 8 ... communication control circuit, 9 ... UI control circuit, 10 ... output circuit, 10a ... data buffer, 10b ... second reading means

Claims (2)

In the data generator for printing which reads out anew after compressing and accumulating the image data, decompresses it and restores it to the original image data and outputs it,
Compression means for compressing image data for each scheduled unit block;
Storage means for storing compressed image data for each unit block;
First reading means for reading the accumulated image data for each unit block from the forward and reverse directions in response to an instruction for front side printing or back side printing;
Decompression means for decompressing the read image data for each unit block;
A data buffer for storing the decompressed unit block image data;
A second reading means for reading the image data on the data buffer from the forward direction in response to an instruction for front side printing, and reading from the reverse direction in response to an instruction for back side printing; Data generator. 2. The front-surface printing instruction is issued at one of the front-surface printing timings in the single-sided printing mode and the double-sided printing mode, and the back-side printing instruction is issued at the back-side printing timing in the double-sided printing mode. The data generator for printing described.

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