JPH0197663A - Compression of font data - Google Patents

Abstract

PURPOSE:To reduce communication time for downloading from a host computer by reading the font data and link data for emulating, and then composing all the font data required for the emulation. CONSTITUTION:Emulation font data are stored in a memory within a host computer or an external storage. The data include special font data EFa for part of an emulation font containing no character image corresponding to a resident font RF stored in a ROM; and linkdata LD indicating the correlation between the common data in the resident font RF and the emulation font. According to this method, the data of the emulation font can be compressed to a great extent, and this decreases the necessary memory capacity and the time required for communication with the host computer.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention maintains one or more sets of resident fonts,
This invention relates to a font data compression method for a printer capable of multiple printer emulations.

Conventionally, for example, optical printers such as laser printers have been capable of various types of printer emulation, and it has been possible to use the same printer to operate in place of different types of printers, such as age wheel printers and wire dot printers. , it is possible to perform operations that match the printer specifications of each company.

In that case, to run a certain emulation, the program data (
emulation program).

Font data (emulation font) necessary for the emulation is essential.

For this reason, conventionally, emulation fonts based on the printer specifications were prepared for all character sets for each emulation, resulting in an extremely large amount of data between the emulation program and the emulation fonts.

This data is stored in the ROM inside the printer,
The information was obtained from an external storage device or host computer that could be connected to the printer.

However, since the amount of data is large, it requires a large capacity internal ROM or external storage device, resulting in high costs, and when downloading from a host computer, it takes a long time to communicate. there were.

1-1 This invention was made in view of the above points, and it is an object of the present invention to compress the amount of data of an emulation font to reduce the capacity of a storage device or to shorten the communication time when downloading from a host computer. With the goal.

In order to achieve the above-mentioned purpose, this invention always uses one printer in a printer capable of multiple printer emulations.
Focusing on the fact that font data constituting more than one character set is stored and maintained in the ROM (this font data is referred to as a "resident font" in this specification), one type of font data for emulation is created. , store link data indicating the correspondence between some dedicated font data that does not have a character image corresponding to the resident font and font data necessary for the emulation of the font data that has a character image that corresponds to the resident font. To provide a font data compression method which reads out the dedicated font data and link data and completes all the font data necessary for emulation by using the resident font when executing emulation.

Hereinafter, a detailed explanation will be given based on one embodiment of the present invention.

FIG. 2 is a block diagram showing the configuration of a printer controller in an optical printer embodying the present invention.

This printer controller has host interface 1
．． External storage device interface (I/F') 2, CPU
3. It is composed of a ROM 4 which is a program memory, a RAMP which is a data memory, and an engine interface 6.

The host interface 1 is an interface for connecting to an office computer, a personal computer, a word processor, etc. (collectively referred to as a "host computer"), and various parallel interfaces or serial interfaces can be selected depending on the host computer.

The external storage device interface 2 is an interface for reading data stored in a ROM, RAM, floppy disk, etc. built into an external storage device such as a removable font cartridge, emulation card, or floppy disk device in this printer. .

The CPt is a central processing unit that centrally controls the entire printer controller, and is a general-purpose 16-bit or 32-bit central processing unit.
Uses Bit CPU.

The ROM 4 contains various processing programs for the CPU 3 to operate this printer controller.

Stores data of resident fonts that constitute at least one character set.

RAM5 is a large capacity random access memory,
It is mainly used for the following purposes.

(a) Input buffer (b) Page buffer (e
) Video buffer (d) Font file (e)
System memory Note that each buffer in (a) to (c) and the font file in (d) are
To secure and use the required amount of AM area in advance.

The input buffer is a buffer that temporarily holds data sent from the host computer through the host interface 1, and is sequentially retrieved by the printer software to locate the source address where the data is actually stored. Then, page data is created in the page buffer by adding information such as a destination address and size that specify where in the video buffer the video data is to be created.

Using this page data and font data (source data) of the font file, video data is created on the video buffer.

The font file includes emulation font data that is completed by emulation font data transferred from the host computer through host interface 1 or read from an external storage device through interface 2, and resident font data held in ROM 4. Data is loaded.

The engine interface 6 is a serial interface for connecting to a printer engine including an image forming unit and its sequence controller. When printing is started, the CPU 3 reads out the video data created in the video buffer on the RAM 55, and processes it. is converted into a serial write signal in synchronization with the write clock from the engine driver and sequentially output.

Next, the font data compression method according to this embodiment will be explained with reference to FIG.

Among the data necessary for the various emulations executed by this printer, the emulation program data is stored in the host computer's internal memory or external storage device as before, but the emulation font data is stored in the ROM4 shown in Figure 2. Dedicated font data EFa that is part of the emulation font that does not have a character image corresponding to the stored resident font RF, and link data LD that indicates the correspondence relationship between the common character data CF in the resident font RF and the emulation font. It is stored in the memory within the host computer or in an external storage device.

As a result, the data of the emulation font can be significantly compressed, and the amount of memory storage or communication time with the host computer can be reduced.

When the printer executes the emulation, it reads out the dedicated font data EFa and link data LD together with the emulation program through the host interface 1 or external storage interface 2 shown in FIG. The common character data CF in the resident font data RF is used to make a correspondence and combined with the dedicated font data EFa to complete all the font data (emulation font) EF necessary for emulation, and the font in RAM 5 shown in Figure 2 is created. Load into file.

Here, the resident font, emulation font, and link data will be specifically explained with reference to FIG.

Font a and font a/ have the same font and size but different character sets, or different correspondences between character codes and character images.

Assume that there are font b and font b'.

Font a and font b are resident fonts, and font a' and font b' are emulation fonts. And aXX, a' XX, in Figure 3
bXX, b' XX indicate character codes.

Among the emulation fonts (font a' and font b'), the shaded portions are character images that do not exist in the resident fonts (font a, font b), and are dedicated font data that must be prepared separately. In other cases, since the character image exists in the resident font, there is no need to prepare character image data, and it is sufficient to prepare link data such as the one illustrated on the next page that shows the correspondence between single character codes.

Then, when executing printer emulation, by sharing or copying the character image of the resident font using this link data, all character images necessary for the emulation font are prepared with dedicated font data other than the shaded area. can do.

As explained above, according to the present invention, the amount of data of an emulation font can be compressed, so the capacity of the memory for storing it can be reduced.

When sending the emulation program and font data from the host computer, the amount of data is reduced, so communication time can be shortened. It can also be effectively used when using the printer's internal memory.

[Brief explanation of the drawing]

FIG. 1 is a font data compression method according to the present invention. FIG. 2 is a block diagram showing the configuration of a printer controller in an optical printer embodying the present invention. FIG. 3 is an explanatory diagram showing an example of resident fonts and emulation fonts. 1...Host interface 2...External storage device interface 3...cpty 4...ROM 5.
・・RA M6°°°Engine Interface

Claims (1)

[Claims] 1. In a printer that holds one or more sets of resident fonts and is capable of multiple printer emulations, some dedicated font data that does not have a character image corresponding to the resident font is used as font data for emulation. and link data indicating the correspondence between the font data that has a character image corresponding to the resident font data and the font data necessary for the emulation, and when executing the emulation, the dedicated font is stored. A font data compression method characterized in that data and link data are read out and all font data necessary for emulation is completed using the resident font.