JPH08230247A - Control device of page printer - Google Patents

Abstract

PURPOSE: To enable the development and storing of compressed data to expanded image data by using a small capacity memory in the control unit of a page printer. CONSTITUTION: A large quantity of image data are processed by an expanding processor 1 developing compressed image data on a small capacity memory, a graphic processor 2 processing expanded image data and a memory access control circuit 5 controlling the access to the memories of both processors.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a page printer control device having a decompression function for compressed image data and a graphic function for enlarging / reducing / trimming image data after decompression.

[0002]

2. Description of the Related Art FIG. 3 is a block diagram of a page printer. 8 is a control unit, 9 is a print data processing unit, 10 is a page memory,
Reference numeral 11 is a data conversion unit, and 12 is a printer unit. The print information from the host device is received by the control unit 8. The control unit 8 decodes the received print information, transfers the character code and the like to the print data processing unit 9, and issues a print instruction. The print data processing unit 9 processes a character code or the like according to a print instruction from the control unit 8, generates print data in a dot pattern format, and stores the print data in the page memory 10. The data conversion unit 11 reads out print data from the page memory 10, converts it into serial dot data, and sends it to the printer unit 12.

By the way, a page printer can print an image such as a picture or a photograph in addition to characters, but the image data is usually in the form of a dot pattern when it is sent from a host device such as a host computer. have. However, in recent years, page printers have come to handle image data in a form in which the dot pattern format image data is converted according to an algorithm and the information amount is compressed. A page printer that handles this compressed image data requires a process (hereinafter referred to as a compressed image decompression process) that decompresses the compressed image data received from the host device in the page printer control device and restores it to image data in dot pattern format. Becomes

Some printers further perform graphic processing (hereinafter simply referred to as graphic processing) on the restored image data in the dot pattern format, such as enlarging / reducing the image and cutting out an arbitrary area of the image. Some things came out. The compressed image decompression process and the graphic process described above are performed by the print data processing unit 9 because it is necessary for the page printer controller to store the data in the page memory 10.

FIG. 4 shows the configuration of the print data processing unit 9 in the conventional page printer control device. Here, the characters are converted into a dot pattern by the dot data conversion unit 13 having font data, and the page memory 10
Sent to Further, the compressed image data is sent to the decompression processor 1 and decompressed according to a predetermined algorithm to be restored to the original image data. The restored image data is sequentially written in the expanded image memory 3. The graphic processor 2 reads the restored image data on the decompressed image memory 3, further performs image enlargement / reduction, cutout of an arbitrary area of the image, and the like, and stores the processed data in the pattern memory 4. After that, the dot data conversion unit 13 reads the dot data from the pattern memory 4, and the page memory 10
Transfer to.

[0006]

In the conventional page printer control apparatus, in the above-described compressed image decompression processing, first, all the compressed image data are restored in the compressed image memory, and the graphic processing is performed after the compressed image decompression processing is completed. It was performing the process of starting the processor.

For this reason, there is a drawback in that a memory having a sufficient capacity to hold the maximum decompressed image data handled by itself must be installed. As a result, in a page printer control device that must handle a large amount of data, it becomes a factor of increasing the size and cost of the device due to the mounting of a large amount of memory, and the amount of memory that can be mounted tends to be limited in terms of cost and physical space. The small page printer controller had to reduce the amount of image data to be handled.

An object of the present invention is to eliminate the above-mentioned drawbacks of the conventional method and to make the actual memory capacity smaller than the expanded image memory capacity capable of storing the expanded image data handled by the page printer controller.

[0009]

The above object is achieved by the memory access control circuit after the compressed image expansion processing by the expansion processor and the graphic processing by the graphic processor are processed in parallel.

[0010]

The memory access control circuit correlatively controls accesses performed by the two processors to and from each other in writing into the memory of the decompression processor and reading from the memory of the graphic processor so as not to exceed a certain range. As a result, the decompressed image memory having only the capacity necessary for holding the data in a certain specific range can process the decompressed image data larger than that handled by the apparatus.

[0011]

FIG. 1 shows an embodiment of the present invention. The decompression processor 1 decompresses the compressed image data and writes the dot pattern data in the decompression image memory 3 via the gate 6. On the other hand, the graphic processor 2 reads out the dot pattern data on the decompressed image memory 3 through the gate 7, performs graphic processing on the dot pattern data, and writes it in an area of the pattern memory 4.

The memory access control circuit 5 controls the access to the decompressed image memory 3 of the decompressing processor 1 and the graphic processor 2 to instruct execution or waiting of the memory access started in each processor, and to actually execute the decompressing image memory 3. Access. Gates 6 and 7 are gates that control the flow of data.

In the page printer controller adopting this embodiment, the maximum amount of expanded image data to be handled (the maximum amount of image data output by the expansion processor 1) is 128 megabytes. In the conventional method, the capacity of the decompression image memory 3 had to be 128 megabytes, but in the present embodiment, this is 64 kilobytes. The memory control method will be described below with reference to the drawings.

FIG. 2 is a conceptual diagram of the decompression image memory 3 in this embodiment. In this figure, the addresses increase from bottom to top in the direction of the arrow in the figure. a) Area of maximum expanded image data 128 megabytes output by the expansion processor 1 or input by the graphic processor 2 b) Physical expansion image memory 3 area of 64 kilobytes, that is, expansion processor 1 and graphic processor 2
The decompressed image memory 3 handled by has a structure in which 2000 blocks of 64 kilobytes are virtually connected, and each block of 64 kilobytes (1) to (2000) is actually recorded on the same memory of 64 kilobytes. It

In this apparatus, in order of processing, the decompression processor 1 first writes decompression image data in the decompression image memory 3, and the graphic processor 2 reads the written data. The decompression processor 1 starts writing data from the hatched portion of the block (1) in the figure and proceeds to write decompressed image data in the direction of the arrow.

The graphic processor 2 performs processing in parallel with the decompression processor 1, and reads the data written by the decompression processor 1 from the shaded portion of the block (1) in the arrow direction. Here, in order to prevent the graphic processor 2 from reading the data that the decompression processor 1 has not yet written, the memory access control circuit 5 precedes the reading process of the graphic processor 2 before the writing process of the decompression processor 1. Control not to let.

When the graphic processor 2 starts the memory reading, the memory access control circuit 5 judges whether the decompression processor 1 has already written the data to the address which the graphic processor 2 is going to read, and is still writing the data. If not, the graphic processor 2 is instructed to wait for the reading operation currently being executed,
If it has already been written, the reading process of the graphic processor 2 is executed as it is.

On the other hand, the following control is performed for the write operation of the decompression processor 1. As described above, blocks (1) to (2000) in FIG. 2 are physically the same memory. That is, for example, the shaded areas in the figure have different addresses for the decompression processor 1 and the graphic processor 2, but have the same address in the actual memory.

Therefore, for example, the graphic processor 2
If the decompression processor 1 has proceeded to write data to the shaded address of the block (2) when the data of the shaded address of the block (1) has not yet been read, the graphic processor 2 is actually stored in the memory. The data that should be read will be rewritten.

In this case, the decompression processor 1 can proceed with the writing within the range of the block (1). That is, the writing can be advanced to the last address read by the graphic processor 2.

However, the graphic processor used in this embodiment has a maximum of 3 with respect to the read address.
Since data before 2 kilobytes may be read again, in the present embodiment, the decompression processor 1 can actually proceed to write 32 kilobytes to the last address where the graphic processor 2 proceeded to read. Is.

From this, the memory access control circuit 5
Determines whether the address from the decompression processor 1 is within 32 kilobytes with respect to the last address read by the graphic processor 2 when the decompression processor 1 starts writing to the memory, and if it exceeds the address,
The decompression processor 1 is instructed to wait for the write operation currently being executed, and if it is within 32 kilobytes, the write processing of the decompression processor 1 is executed as it is.

Under the control of the memory access control circuit 5 as described above, the expanded image memory 3 of 64 kilobytes processes the expanded image data of 128 megabytes.

[0024]

According to the present invention, a page printer controller having graphic functions such as a function for decompressing compressed image data and a function for enlarging / reducing / trimming image data after decompression possesses more than the amount of decompressed image data handled by the device. The expansion image memory capacity can be reduced.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of a compressed image expansion processing and graphic processing unit in a page printer control device of the present invention.

FIG. 2 is a conceptual diagram of a decompression image memory.

FIG. 3 is a configuration diagram of a page printer control device.

FIG. 4 is a configuration diagram of a compressed image expansion processing and graphic processing unit in a conventional page printer control device.

[Explanation of symbols]

1 is a decompression processor, 2 is a graphics processor, 3
Is an expanded image memory, 4 is a pattern memory, 5 is a memory access control circuit, and 6 and 7 are gates.

Claims (1)

[Claims] 1. A page printer control device having a function of expanding compressed image data and graphic functions such as enlargement / reduction / trimming of image data after expansion expands image data in a compressed data format sent from a host device. A decompression processor that restores the dot pattern format, a memory that temporarily stores the image data that is restored to the dot pattern format by the decompression processor, a graphic processor that reads the decompressed image data on the memory and performs graphic processing, and a decompression processor. A memory access control circuit for controlling access to the memory of the graphic processor is provided, and the capacity of the memory is set as a partial capacity for holding a certain range for the expanded image data, and the expanded image data is processed in the memory. Page printer controller according to claim.