JPH04185365A - Printer device - Google Patents

Abstract

PURPOSE:To ensure that a large amount of print information can be processed efficiently by storing print information sent from a host computer in a storage device in a compressed form, and then decoding the compressed print information after reading it from the storage device, prior to recording said information in a recording medium. CONSTITUTION:If it is interpreted that data entered from a host computer is control information parameters, these parameters are stored in RAM 12. On the other hand, if it is interpreted that entered data is a character code for printing, character code data is compressed. Then, given a single line of character pattern which is output as a continuous character string containing no vector data such as figures, it is calculated that a single line of character code data should be a continuous binary bit pattern of 2112 bits, based on an assumption that 132 characters are output for each single line. Further, it is considered that this bit pattern has a high redundancy, so that a single line of character code data can be compressed on an assumption that it is equal to a binary bit pattern. In this case, said data is processed in a compressed form according to an MH compression method and therefore, complete information restoration during following decoding process is ensured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a printer device, and particularly to a page printer device.

[Prior Art] An example of page editing processing in a conventional page printer device will be described with reference to FIG.

First, print information for one page sent from the host computer 31 is stored in the page buffer memory 33 via the interface 32. Next, based on a command from the CPU 41, a character code, which is printing information, is read from the page buffer memory 33, stored in the character font memory 34, a certain character font is called, and a bitmap is developed in the text bitmap memory 35.

If a form overlay instruction is included in the print information, patterned characters, symbols, etc. are developed in the form overlay memory 36.

Furthermore, the parallel-to-serial converter 37 reads and inputs the developed dot images from the text bitmap memory 35 and the form overlay bitmap memory 36, calculates the logical sum of the read parallel data, converts it into serial data, and records it. Send to Department 38. Finally, the recording unit 38 scans the light beam irradiated onto the photoreceptor based on the input image information, and forms a static 1:1 image on the photoreceptor.

Here, the CPU 41 has a ROM 39 that stores a control program for executing page editing, print processing, etc., and a RAM 40 that is used as a work area during the execution of various programs. Additionally, the components of the page printer device exchange information with each other via the CPU bus 42.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional example, the print information sent from the host computer was stored in the page buffer as a character code, such as an ASCII code. A large capacity memory is required to accommodate one page's worth of character codes, which has the disadvantage of increasing the cost of the device.

The present invention has been made in view of the above conventional example, and an object of the present invention is to provide a printer device that can efficiently process a large amount of print information using a small capacity memory.

[Means for Solving the Problems] In order to achieve the above object, the printer device of the present invention has the following configuration. That is, the printer device receives print information from a host computer, stores the print information, and then records the print information on a recording medium, and compresses the print information transmitted from the host computer into predetermined amounts. A printer device comprising a compression means, a storage means for storing the print information compressed by the compression means, and a decoding means for reading and decoding the compressed print information from the storage means. .

[Operation] With the above configuration, the present invention compresses and stores the print information sent from the host computer in the storage means,
It operates to read compressed print information from the storage means and decode it before recording it on a recording medium.

[Embodiments] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram showing the configuration of a page printer device that is a typical embodiment of the present invention. In Figure 1,
The page printer device includes an interface 2 that receives print information sent from a host computer 1 (hereinafter referred to as the host), and a compression circuit 3 that compresses the print information.
, a page buffer memory 4 (hereinafter referred to as page buffer) that stores compressed print information, a decoding circuit 5 that decodes the compressed print information into original data, and a page buffer memory 4 that stores compressed print information. Reading from character font memory 6 which stores character fonts for referencing fonts, text bitmap memory 7, form overlay bitmap memory 8, text bitmap memory 7, and form overlay bitmap memory 8 A parallel-to-serial conversion unit 9 calculates the logical sum of the parallel data and converts it into serial data, scans the light beam irradiated onto the photoreceptor based on the input raster data, and forms an electrostatic latent image on the photoreceptor. It is composed of a recording section 10 and a CPU 13 that controls the entire page printer device.

Here, the CPU 13 has a ROM 11 that stores a control program for controlling page editing, print processing, etc., and a RAM 12 that is mainly used as a work area during execution of various programs.

Further, the CPU bus 14 is used as an information transmission path when each component of the page printer device exchanges information.

Further, in the recording unit 10 of this embodiment, it is assumed that printing is performed by a known electrophotographic process, and a description regarding the electrophotographic process will be omitted.

Next, flowcharts 1 and 2 shown in FIGS. 2(a) and 2(b) are performed for each of the data compression processing and data decoding processing executed using the page printer device having the above configuration.
Explain using. In particular, a case will be described here in which data compression processing and data decoding processing are performed for each line of character data input to be printed on a page printer device. Therefore, it is assumed that one line of character data information can be input into the interface 2. For example, if the page printer device of this embodiment can print a maximum of 132 characters per line, the character codes and control information for 132 characters (for example, control information indicating the end of a line or the end of a page) are sent to the interface 2. shall be able to accommodate.

First, in step S1 of FIG. 2(a), it is checked whether the input data from the host 1 is a printing character code or a control information parameter.

If it is determined that the input data is a control information parameter, the process proceeds to step S2, and the parameter is stored in RAMI2. On the other hand, if it is determined that the input data is a character code for printing, the process proceeds to step S3, where the character code data is compressed.

Now, when a page printer device like the present embodiment is capable of outputting "kana-kanji" like Japanese, the character code is usually expressed in 2 bytes per character. Here, if the character pattern of one line to be output is a continuous character string that does not include vector data such as figures, and if 132 characters are output per line, then the character code data for one line is a 2-byte memory. 132 characters x 8 = 2112 bits, that is, it can be said to be a continuous binary bit pattern of 2112 bits. In addition, such a bit pattern has consecutive bits "0" and "1", that is, it can be said to have a high degree of redundancy, so one line of character code data can be regarded as a binary bit pattern. It becomes possible to compress. In this embodiment, the data is compressed according to the MH compression method used in facsimile. This method does not cause information loss even if the information is compressed, so the information can be completely restored in the subsequent decoding process.

Next, in step S4, the compressed data is stored in the page buffer 4. Then, until it is determined in step S5 that data for one page has been received, steps 81 to
Repeat the process of S5.

In the manner described above, the character data compression process is completed.

Next, when bitmap expansion is performed based on the character data compressed in the bitmap memory, the character data is decoded. First, in step S6 of FIG. 2(b), one line of character information is read from the page buffer 4. Subsequently, in step S7, the data compressed in step S3 according to the MH method is decoded. This decoding process follows a known technique and will not be described here. Furthermore, in step S8, the character font memory 6 is stored based on the decoded data.
refers to the character pattern and expands it into bitmap memory. The processes of steps 86 to S9 are repeated until it is determined in step S9 that the bitmap development for one page is completed.

In this manner, the character data decoding process is completed.

Therefore, according to this embodiment, the character code sent from the host is compressed in units of character output for one line and stored in the page buffer, so that the memory capacity of the page buffer can be reduced.

In the above embodiment, an example was explained in which the compression process is performed each time one line of print information is received from the host computer, but it is also possible, for example, to perform the compression process after receiving -pages of print information. .

Further, in the above embodiment, a case has been described in which compression and decoding processing of print information is performed by hardware, but it is also possible to perform similar processing by software.

Further, in the above embodiment, compression processing was performed according to the MH compression method, but the present invention is not limited to this as long as the compression method can completely decode the information.

[Effects of the Invention] As explained above, according to the present invention, print information sent from a host computer can be compressed and decoded, so a large amount of print information can be efficiently stored simultaneously using a small memory capacity. There is an effect that can be processed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a page printer device that is a typical embodiment of the present invention, FIGS. 2(a) to 2(b) are flowcharts showing character code compression processing and decoding processing procedures, and FIG. 3 is a block diagram showing the configuration of a conventional page printer device. In the figure, 1... host computer, 2... interface, 3... compression circuit, 4... page buffer memory, 5... decoding circuit, 6... character font memory, 7...・Bitmap memory for text, 8...
Bitmap memory for form overlay, 9... Parallel-serial conversion circuit, 10... Recording section, 11...
・ROM, 12...RAM, 13...CPLI, 1
．． 4...CPU bus. Patent applicant Canon Co., Ltd. agent Patent attorney Yasunori Otsuka (1 other person) (0)
(b) Figure 2

Claims (1)

[Scope of Claims] A printer device that receives print information from a host computer, stores the print information, and then records the print information on a recording medium, the printer device storing the print information transmitted from the host computer. It is characterized by comprising a compression means for compressing each quantitative amount, a storage means for storing the print information compressed by the compression means, and a decoding means for reading and decoding the compressed print information from the storage means. printer device.