JPH05301391A - Printing device - Google Patents

Abstract

PURPOSE:To obtain output image data for multiple pages with a little memory quantity. CONSTITUTION:A developing circuit 40 stores output image data in a frame memory 42. A memory compaction circuit 44 compacts the output image data of the frame memory 42 and stores in a work memory 46. A memory extending circuit 48 extends the compacted data of the work memory 46, restores the former output image data so as to supply to an output circuit 50.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing device, and more particularly to a printing device for printing data output from a data processing device such as a computer on paper.

[0002]

2. Description of the Related Art FIG.
The schematic block diagram of a printer is shown. Reference numeral 10 is a printing device, 12 is an external device that outputs data to be printed by the printing device 10, and 14 is a sheet on which data is printed.

In the printing apparatus 10, the receiving circuit 16 receives the data from the external apparatus 12, the analyzing circuit 18 analyzes the received data, and the expanding circuit 20 uses the bit map based on the analysis result of the analyzing circuit 18. Create an output image of
It is stored in the frame memory 22. Frame memory 2
2 may be prepared for a plurality of frames. The output circuit 24 controls the laser beam for the photosensitive drum to be turned on / off and transfers the laser beam onto the photosensitive drum according to the output image developed in the frame memory 22, and is fixed on the paper 14 by a so-called electrophotographic method, that is, Print.

[0004]

In the conventional example, since the bit map data of the output image as it is is stored in the frame memory 22, a large memory capacity is required. For example, if you can store multiple pages,
It will be a huge amount of memory. By the way, A4 size binary bit map data of 300 dpi (dot per
To store in inches) resolution, about 1 per page
You will need megabytes.

An object of the present invention is to provide a printing apparatus that requires a small amount of memory in the frame memory 22.

[0006]

According to a first aspect of the present invention, there is provided a printing apparatus which comprises an output image forming means for forming output image data from received data, a compression means for compressing the output image data, and a compression means for compressing the output image data. Storage means for temporarily storing the decompressed data, decompression means for decompressing the compressed data stored in the storage means, and output means for outputting based on the output image data decompressed by the decompression means. And

A printing apparatus according to a second aspect of the present invention is a printing apparatus that expands print data into an output image of the bit map format and prints the received data, and expands the received data in predetermined segment units. A compression unit for compressing the output image data expanded by the expansion unit in units of the predetermined segment, a storage unit for temporarily storing the data compressed by the compression unit, and a compressed data stored in the storage unit for a predetermined segment. It is characterized in that it comprises an expanding means for expanding in units and an output means for outputting based on the output image data expanded by the expanding means.

[0008]

Since the output image data is stored in the storage means in the compressed form, many pages can be stored with a small amount of memory.

Further, in the second invention, the amount of frame memory required for developing the output image data is reduced to at most the size of the above segment, and is reduced. Also, the amount of memory required to store the output image data is reduced.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a schematic block diagram of an embodiment of the present invention. Reference numeral 30 is a printing device according to an embodiment of the present invention, 32 is an external device for outputting data including image data to be printed, and 34 is a printing paper.

In the printing device 30, the receiving circuit 36 receives the data from the external device 32, the analyzing circuit 38 analyzes the received data, and the expanding circuit 40 analyzes the bit of the output image based on the analysis result of the analyzing circuit 38. The map data is formed and stored in the frame memory 42. So far,
It is the same as the conventional example.

The memory compression circuit 44 compresses the data of the output image stored in the frame memory 42 and stores it in the work memory 46. When the compressed data is stored in the work memory 46, the frame memory 42 is released, and the data of the output image of the next page can be stored. Since compressed data is stored in the work memory 46, the memory amount may be relatively small even when storing a plurality of pages.

The memory expansion circuit 48 reads out and expands the compressed data in the work memory 46 in accordance with the progress of printing. The output circuit 50 prints a corresponding image on the paper 34 according to the output image expanded by the memory expansion circuit 48 as in the conventional example.

Memory compression circuit 44 and memory expansion circuit 4
A known technique can be used for compression / decompression by 8 and is not limited to a specific method. It may be performed by software or hardware.

FIG. 3 shows a flowchart of processing in the expansion circuit 40. First, the frame memory 42 is cleared (S1), and the output image is developed based on the analysis result of the analysis circuit 38 (S2). After expanding one page (S
3) Request the memory compression circuit 44 to compress the output image data written in the frame memory 42 (S).
4). When the compression is completed (S5), the process returns to S1 and the expansion process of the next page into the frame memory 42 is performed.

FIG. 4 is a block diagram showing a concrete circuit configuration for realizing this embodiment. Reference numeral 60 is a printing device corresponding to the printing device 30 of FIG. 1, and 62 is a host computer corresponding to the external device 32. In the printing device 60, 64 is an input interface for receiving print data from the host computer 62, 66 is a CP for controlling the whole and performing the functions of the analysis circuit 38 and the development circuit 40.
U and 68 are ROMs for storing operation programs of the CPU 66 (programs related to the flowchart shown in FIG. 3) and character fonts and patterns, and 70 is a CPU.
A work area 66, a reception buffer for receiving data from the host computer 62, a RAM functioning as a storage area for page data and the like for constructing an output image from the received print information.

Further, 72 is a frame memory for storing an output image, 74 is a memory compression circuit, and 76 is a RAM.
Is a work memory, and 78 is a memory expansion circuit. These correspond to the frame memory 42, the memory compression circuit 44, the work memory 46, and the memory expansion circuit 48, respectively. 80 is an output interface,
A system bus 82 connects the circuits 64 to 80 to each other. Reference numeral 84 is an output circuit corresponding to the output circuit 50.

The work memories 46 and 76 may be hard disks instead of RAM. Further, the compressed data by the memory compression circuit 44 may be returned to the frame memory 42 so that it can be used by the expansion circuit 40. For example, when implementing the overlay function of the page, the output image of the overlay page can be compressed, expanded on the frame memory and overlapped, saving the memory amount and saving the overlay data. The redeployment process can be omitted.

Depending on the compression / expansion algorithm, the data expanded by the memory expansion circuit 48 may not be directly supplied to the output circuit 50, but may be supplied to the output circuit 50 via the work memory. This is effective when the order of the decompressed data and the order of the data to be input to the output circuit 50 do not match and the data order needs to be rearranged. Of course, this does not prevent understanding that such a function and processing are included in the memory expansion circuit 48.

Next, a description will be given of an embodiment in which one page is divided into a plurality of segments and applied to a printing apparatus which prints in each segment. FIG. 5 shows a schematic block diagram of the embodiment. Reference numeral 130 is a printing device according to an embodiment of the present invention, 132 is an external device that outputs data to be printed including image data, and 134 is a printing paper.

In the printing device 130, the receiving circuit 136 is
The data from the external device 132 is received and the analysis circuit 138
Analyzes the received data and checks which data should be expanded into which divided portion (hereinafter referred to as a paint segment).

The expansion circuit 140 expands the output image data in the frame memory 142 in paint segment units. Output image data unnecessary for the expansion processing of the expansion circuit 140 is compressed by the memory compression circuit 144 and stored in the work memory 146. Expansion circuit 140
Is required to expand the output image on the frame memory 142, and the compressed data of the output image stored in the work memory 146 is stored in the memory expansion circuit 14.
8 is expanded and supplied to the frame memory 142.

In this manner, the expansion circuit 140 can expand a large amount of image data on the frame memory 142 having a small memory amount.

When the expansion of one page is completed, the memory expansion circuit 148 expands the compressed data stored in the work memory 146 and supplies it to the output circuit 150 in the output order. The output circuit 150 prints a corresponding image on the paper 134 as in the conventional example and the embodiment shown in FIG.

A known technique can be used for compression / expansion by the memory compression circuit 144 and the memory expansion circuit 148, and the method is not limited to a particular method. Similar to the embodiment of FIG. 1, this may be done by software or hardware.

FIG. 6 shows an output image when one page of the output image is divided into N paint segments, a frame memory 142 and a work memory 146.
It is a figure which shows the relationship with. Paint segments # 1 to #N of the output image are # 1 on the work memory 146.
Corresponding to #n, the data of one paint segment in the frame memory 142 is stored in the frame memory 142.

FIG. 7 shows a flow chart of the expansion processing in the expansion circuit 140. First, the paint segment number to be developed is determined (S11), and it is checked whether or not the number matches the paint segment number currently developed (S12). If they do not match, the data of the current paint segment is compressed by the memory compression circuit 144 and stored in the work memory 146 (S13), and the compressed data of the paint segment to be expanded is stored in the work memory 1.
The data is read out from memory 46 and expanded by the memory expansion circuit 148 (S14). If they match, S13 and S14 are bypassed.

Regarding the paint segment of interest,
The output image data is expanded on the frame memory 142 (S15). Steps S11 to 15 are repeated until the development of all segments is completed. In the first paint segment of the page, after the paint segment number is determined (S11), the process immediately proceeds to S15 and the output image data is expanded in the frame memory 142.

FIG. 8 shows a specific circuit configuration block diagram for realizing this embodiment. Reference numeral 160 is a printing device corresponding to the printing device 130 of FIG. 5, and 162 is a host computer corresponding to the external device 132. In the printing apparatus 160, 164 is an input interface for receiving print data from the host computer 162, 166 is for controlling the whole, and an analysis circuit 138 and a development circuit 140 are also provided.
A CPU that fulfills the function of 168, a ROM that stores an operation program of the CPU 166 (a program related to the flowchart shown in FIG. 7, etc.) and a character font pattern, 170 is a work area of the CPU 166, and received data from the host computer 162. Receiving buffer, RAM that functions as a storage area for page data, etc. for constructing an output image from received print information
Is.

Further, 172 is a frame memory for storing an output image, 174 is a memory compression circuit, 176 is a work memory composed of RAM, and 178 is a memory expansion circuit. These are the frame memory 142, the memory compression circuit 144, and the work memory 14, respectively.
6 and the memory expansion circuit 148. Reference numeral 180 is an output interface, and 182 is a system bus that interconnects the circuits 164-180. An output circuit 184 corresponds to the output circuit 150.

The work memories 146 and 176 are RAMs.
Alternatively, it may be a hard disk. In the above embodiment, the output (printing) is started after the expansion of one page is completed, but the output (printing) is started from the page segment where the expansion is completed, even if the expansion of all the one page is not completed. ) May be started. By doing so, output (printing) and expansion are processed in parallel, and throughput is improved.

[0033]

As can be easily understood from the above description, according to the present invention, output images of a plurality of pages can be held with a small memory amount. When applied to the segment method, the amount of memory required to expand the output image can be significantly reduced.

[Brief description of drawings]

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

FIG. 2 is a configuration block diagram of a conventional example.

FIG. 3 is a flowchart of expansion processing of the embodiment shown in FIG.

FIG. 4 is a specific circuit configuration example of the embodiment shown in FIG.

FIG. 5 is a configuration block diagram of a second embodiment of the present invention.

FIG. 6 is a conceptual diagram of division processing of the embodiment shown in FIG.

FIG. 7 is a flowchart of expansion processing of the embodiment shown in FIG.

FIG. 8 is a specific circuit configuration example of the embodiment shown in FIG.

[Explanation of symbols]

10: Printing device 12: External device 14: Paper 16:
Reception circuit 18: Analysis circuit 20: Expansion circuit 22: Frame memory 24: Output circuit 30: Printing device 3
2: External device 34: Printing paper 36: Reception circuit 3
8: Analysis circuit 40: Expansion circuit 42: Frame memory 44: Memory compression circuit 46: Work memory 4
8: Memory expansion circuit 50: Output circuit 60: Printing device 62: Host computer 64: Input interface 66: CPU 68: ROM 70: RAM 72: Frame memory 74: Memory compression circuit 76: Work memory 78: Memory expansion circuit 80: output interface 82: system bus 84: output circuit 130: printing device 132: external device 134: printing paper 136: receiving circuit 138:
Analysis circuit 140: Expansion circuit 142: Frame memory 144: Memory compression circuit 146: Work memory 148: Memory expansion circuit 150: Output circuit 16
0: printer 162: host computer 164:
Input interface 166: CPU 168: RO
M 170: RAM 172: Frame memory 17
4: Memory compression circuit 176: Work memory 17
8: Memory expansion circuit 180: Output interface
182: System Bus 184: Output Circuit

Claims (2)

[Claims] 1. An output image forming means for forming output image data from received data, a compression means for compressing the output image data, a storage means for temporarily storing the data compressed by the compression means, and the storage means. A printing apparatus comprising: a decompressing unit for decompressing the compressed data stored in the decompressing unit, and an output unit for outputting the decompressed data based on the output image data. 2. A printing device for expanding print data into an output image in a bit map format and printing the expanded image, the expanding means expanding the received data in a predetermined segment unit, and the output expanded by the expanding means. Compression means for compressing the image data in the predetermined segment unit, storage means for temporarily storing the data compressed by the compression means, decompression means for decompressing the compressed data stored in the storage means in the predetermined segment unit, A printing device comprising: an output unit that outputs the output image data expanded by the expansion unit.