JPH02234286A - Font pattern forming device - Google Patents

Abstract

PURPOSE:To improve a whole throughput by expanding a font cache area according to a prescribed rule as RAM capacity is expanded. CONSTITUTION:A font pattern generated in a font pattern generator 204 is stored into a font cache memory 207 so as to be retrievable by a dot image. Further a memory space is dynamically altered so that an expanded RAM port 205, which is not ordinarily used for the storage of a font pattern but is storable by the dot image, ma be incorporated to a part of a font cache memory 207, and the space of the font cache memory 207 to store the font pattern as necessary is increased/decreased. Thus since the font cache area can be expanded according to a prescribed rule as the RAM capacity is expanded, the whole RAM space can be effectively utilized, and the throughput of the whole device can be improved.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a generation device for generating font patterns such as character symbols, and more specifically, for example, when a removable optional RAM board is installed. This paper concerns improvements to the dynamic allocation (location) of font pattern storage areas. [Prior Art] Conventionally, among output devices such as printers, many output devices other than type printers output characters and symbols in dot patterns (hereinafter referred to as font patterns or character patterns). Character code data given from a host computer or the like is developed in advance into a frame buffer memory (image memory for one page) into a character pattern using a character generator and output.

The way character pattern information is stored in a character generator can be roughly classified into the following three ways. ■: A font in which the character pattern is composed of a simple dot matrix itself (unprocessed) (hereinafter collectively referred to as the "dot matrix") ■: Memorized as the outline of the character, the stroke, or the coordinate point relative to the character origin fonts (hereinafter collectively referred to as "vector fonts") ■: Fonts that are formed by processing a dot matrix pattern using some kind of compression technology (for example, run-length encoding method) (hereinafter referred to as "compressed fonts") collectively.

) Among these, "dot matrix fonts" are most commonly used in conventional output devices. The reason this is so widely used is that since the character patterns themselves are stored on a dot matrix, they can be expanded easily and quickly into the frame buffer memory.

However, as output devices become more sophisticated and have higher resolution, it becomes necessary to rotate and transform characters, so-called “
"Vector fonts" are also beginning to be commonly used.Also, "compressed fonts" have come to be used as a measure to cope with the increase in font size due to higher resolution.More recently, mixed types of these It has appeared up to.
If all of these are called "non-dot matrix type",
Although "non-dot matrix" fonts have advantages that "dot matrix" fonts do not have, they generally take longer to process characters, etc. in frame buffer memory than do simple "dot matrix" fonts. The disadvantage is that it requires a lot of energy.

There is a "font cache method" as a method to solve this problem. This is a method that contributes to improving overall processing speed by converting a "non-dot matrix" font to a "dot matrix" type font in advance and storing and storing the pattern when it is expanded to the frame buffer memory. As such, it is used in many output devices. The pattern storage area for this purpose is called a font cache memory, and this area is usually reserved in a random access memory (RAM) built into the main device.

On the other hand, as a method to increase the expandability of the device itself, the overall R
There are also many devices whose AM capacity can be easily expanded using an option board or the like. This expansion RAM board is typically used for general purposes.

[Problems to be Solved by the Invention] Therefore, in conventional models of this type, even if such an expansion RAM board is installed, the font cache memory area is fixedly secured, so the font cache memory is does not actually increase in size and is not used as font cache memory, so when the font cache memory runs out of space,
This results in a situation where data in the existing cache memory is erased and new patterns such as characters are stored. Therefore, the addition of the extended RAM board is meaningless, at least from the perspective of the font cache memory, and this causes a drop in the efficiency of outputting characters and the like as visible images.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to propose a font pattern generation device that can dynamically change the area in which font patterns are stored as necessary.

[Means for Solving the Problems] The configuration of the present invention for achieving the above problems includes a pattern generating means for generating font patterns such as character symbols, and storing the generated font patterns in a searchable manner as dot images. A first storage means, a second storage means which is not normally used for storing font patterns but can be stored as a dot image, and the second storage means is incorporated into a part of the first storage means. , and changing means for dynamically changing the memory space.

[Embodiment] A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings. This embodiment deals with "non-dot matrix" fonts, and in an output device whose RAM capacity can be increased by an expansion board, etc., the "font cache" area is expanded according to a certain predetermined rule as the RAM capacity is expanded. This made it possible.

FIG. 2 shows a laser beam printer according to an embodiment of the present invention (
FIG. 2 is a sectional view showing the internal structure of the LBP (hereinafter also referred to as LBP). The laser beam printer shown in the figure is capable of registering patterns such as characters and regular formats (form patterns) from a data source (not shown).
In the figure, 10o is the LBP main body, which converts character information (character code) etc. supplied from an externally connected host computer (201) into corresponding character patterns, form patterns, etc. and prints it on paper, which is a recording medium. 300 is an operation panel on which operation switches, LED indicators, etc. are arranged; 101 is an LBP 100 that forms an image;
This is a printer control unit that performs overall control and analyzes character information etc. supplied from the host computer. The printer control unit 101 mainly converts text information into a video signal of a corresponding pattern such as text and sends it to the laser driver 10.
Output to 2. Laser driver 102 is semiconductor laser 1
03, and switches on/off the laser beam 104 emitted from the semiconductor laser 103 according to the input video signal. The laser beam 104 is swung left and right by a rotating polygon mirror 105 and is directed to an electrostatic drum 106.
A latent image of a pattern such as a character is formed on the electrostatic drum 106. This latent image is developed by a developing unit 107 around the electrostatic drum 106 and then transferred onto paper. Cut sheet paper is used as the paper, and the cut sheet paper is stored in a paper cassette 108 attached to the LBP 100, taken into the device by a paper feed roller 109 and transport rollers 110 and 111, and transferred to an electrostatic drum 106.
is supplied to FIG. 1 shows an example of the configuration of a control system of the output device shown in FIG. The control system with the illustrated configuration is an example of a case where character code data and control commands sent from a print information generation source are input, and printing is performed by a printing mechanism such as a laser beam printer that prints a document page by page. ing. Here, 201 is a host computer as a print information generation source that generates character code data and control commands. 202 is an input interface section consisting of a receiving interface circuit for receiving character code data and control commands generated from the host computer 201, and 203 is an input buffer memory consisting of a RAM for temporarily storing the character code data and control commands. be. Reference numeral 204 denotes a character pattern generator, which is composed of a ROM that stores character patterns compressed and encoded using the run-length technique and a control circuit thereof, and calculates the address of each character pattern from character code data. It also has a code converter function.

A RAM cartridge 205 is composed of a RAM element with a capacity of IM bytes, its control circuit, and a connector 206 for attachment to the main unit. This cartridge 2
05 is directly connected to the bus of the CPU 208 of the main printer by being attached to the main printer via the socket 212.

207 stores the decoded pattern into a raw dot matrix pattern, such as a compression-encoded character pattern;
This is a font cache memory consisting of RAM for storage. By storing decoded character patterns in the font cache memory, there is no need to decode once-used characters again, and high-speed printing becomes possible.

208 is a general-purpose microprocessor that controls the entire control section, has a built-in ROM 2 1 2, and controls the entire control system according to a program stored in the ROM.

Reference numeral 209 is a frame buffer for one page consisting of a RAM, which is used to develop an image of a character pattern, etc., once developed in the font cache memory from a character etc. pattern generator, into an appropriate position according to a print position command from the host computer. It's memory. 210 is an output interface section that generates a video signal according to the dot pattern information from the frame buffer memory 209 and interfaces with the page printer printing 111; 211 receives the video signal from the output interface section 210 and outputs the video signal; Page printer that prints image information by
1 is the CPU board on which this control mechanism is mounted. FIGS. 3A to 3C are diagrams for explaining the actual memorization method of "dot matrix font" and "non-dot matrix font" in the embodiment. Figure 3A is a diagram that visually represents the unprocessed "dot matrix font", and in the diagram, the "●" part of the character pattern etc. is imaged in black, and the "・" part is not imaged. This character pattern is 32 dots wide and 32 dots high.
etc. are line numbers. It can be seen that storing the characters in Figure 3A in the form of a "dot matrix pattern" requires 128 bytes of memory. Figure 3B shows how the visually represented character patterns as shown in Figure 3A can be stored in ROM or R
This is a hexadecimal representation of the memory contents when stored in the unprocessed "dot matrix pattern" format in the AM, and the corresponding bits are "l" and "1" for the parts where the image is formed in black. In the non-image forming portion, the corresponding bit is set to “0”. In this embodiment, the character patterns etc. stored in the font cache memory 207 are as follows:
This is the form shown in FIG. 3B. Figure 3C shows the hexadecimal representation of the contents of the memory when stored in the form of a "non-dot matrix pattern" font. In the case of this embodiment, it is a "compressed font" using a run-length method. Specifically, this run-length method consists of the following rules. ■: Each code unit is 4 bits.

■: Each horizontal direction (scan direction) of the font pattern of one character has a delimiter code "E" (hexadecimal).

◎: The code “E” means that all bits in the line pattern following this “E” are set to “O”. ■: A scan line that has exactly the same content as the previous scan line is represented by the code “F”. (2): Each code unit (4 bits) within a scan is represented in the order of "O" (white) and "l" (black), and this is repeated.

■: However, if the length is 13 or more, code “D”
” (hexadecimal) followed by 1 code unit (4 bits)
Expressed as the sum of That is, only in this case, the length is represented by 8 bits. For example, in FIG. 3C, the content of the 14th scan is "8".
464" (hexadecimal), r"O" is 8 bits from the left,
"1" is 4 bits, "0" is 6 bits, "l" is 4 bits, and hereinafter "O"J represents image formation. Also, the content of the 24th scan is “44D14E”
(Hexadecimal) is also from the left: “4 bits of “0”, “1”
” is 4 bits, “0” is 14 bits (13+1), “1”
” represents 4 bits, hereinafter “O”J, to form an image. By using the above rules, the character etc. pattern represented in Figure 3B requires only 39 bytes of memory. I understand.

In this embodiment, character pattern generators 2 to 4 are "non-dot matrix fonts" using this technique.

FIGS. 4A to 4C are memory maps illustrating the state of memory usage.

FIG. 4A is a memory map of the memory space when the entire device is viewed from the CPU 2.08, and explains a state in which a total of 16 MB of space is allocated to each device (memory). From address 08 to address FFFFF■, CPU208
This is the storage area for the control protocol of IFFFFF. from address 1000008. The space up to the address is allocated to the built-in ROM of the character pattern generator 204. The RAM built into the main unit is 3FF from address 200008.
2MB up to address FFFH is allocated and RA
An M element is also mounted. The built-in RAM is the memory in the font cache memory 209 and frame buffer memory 209 when the cartridge 205 is not installed in FIG. Furthermore, the expanded RAM is 4FFFF from address 400000s.
IMB up to FH address is allocated and extended RA
The mounting on the M board 205 is also IMB.

Figure 4B shows the total RAM (i.e., only the built-in RAM) when the expansion RAM board 205 is not installed.
It explains the allocation of RAM internally for purposes of use,
25% of the total area is used as font cache
, that is, 0.5MB is secured.

Further, FIG. 4C explains the allocation of the entire RAM according to usage purposes when the IMB expansion RAM board 205 is installed. Of the IMBs on this board 205, 0
．． 25MB is allocated to the font cache, 0.
Allocated for 75MB work. Therefore, although the area used as font cache remains the same at 25% of the total, it can be seen that the capacity has been expanded to 0.75MB. In the socket 212 on the main body side,
It is equipped with a switch (not shown) that turns on when pressed.
When the cartridge 205 is installed, this switch is pressed, so that it can be determined whether the cartridge 205 is installed.

Figure 5 shows the internal RA
This is a font table developed in the work area of M.

This font table is formed with each unit having a fixed length for each character code, etc., and the stored information is 1 indicating whether or not a font pattern has already been developed in the font cache memory 209. Bit information and
It consists of an address field in the cache memory 209 when expanded.

FIG. 6 is an overall flowchart showing the control of the CPU 208. From then on, according to the flowchart in Figure 5,
When the printer unit and CPU board 101 of this embodiment are powered on, the character code data stored in the input buffer memory 202 is converted into character, etc. pattern data, and the character, etc. pattern is transferred to the frame buffer memory 209. , operations up to printing by the page printer printing unit 211 will be explained.

When power is applied to the CPU board 101, the CPU 20
8, after completing a predetermined initialization process (not shown), it is immediately determined in step S1 whether or not the RAM cartridge 205 is installed in the socket 212. If it is attached, the process advances to step S2. In step S2, each area of the total RAM capacity of 3 MB is initialized to match the memory layout shown in FIG. 4C in which the font cache is 0.75 MB. During this initialization, the fifth
The bits shown in the figure that indicate whether or not the font pattern is developed in the cache memory are set to "O".

If the RAM cartridge 205 is not installed,
Proceeding to step S3, the font cache is set to 0.5 MB of the total RAM capacity fi2 MB, and each area is initialized to match the memory layout shown in FIG. 4B. In this initialization as well, the bits shown in FIG. 5 that indicate whether or not the font pattern is developed in the cache memory are set to "0".

Next, the process advances to step S4, and print data sent from the host computer 201 is received from the input buffer memory 203 via the input interface section. Here, the information for printing one character, that is, the character code,
After receiving the designation of the print position, the type of font to be printed, etc., the process advances to step S5. In step S5, the character code is checked to determine whether it is a page break (form feed) code. If it is not a page break code, it is a character code to be printed, so step S
In step 6, it is checked whether the character pattern to be printed is already stored in the font cache memory 207. This test is performed using the test bits shown in FIG.

If it is already stored, proceed to step S8,
The corresponding character pattern is transferred from the font cache memory 207 to the frame buffer memory 209 while controlling where in the frame buffer memory the image is to be formed.

If it is determined in step S6 that the frame buffer is not stored in the frame buffer, step S3 and step S
Using the cache memory space left during font caching in step 2, the required character, etc. pattern is read from the character, etc. pattern generator 204 and developed in the font cache memory 209. At this time, the check bit is set to "1" and the storage location in the font cache memory is also stored.

Incidentally, if the free space in the cache memory 209 is already full, this is handled by sequentially deleting the characters, etc. patterns cached earliest using the FIFO method. Also, after step S7, step S
8, the process of step S8 described above is the same.

After the character pattern for one character is developed in the frame buffer memory 209 in this manner, the process returns to step S4 and the above-described process is repeated. During this process, if it is determined in step S5 that it is a page break code, the process proceeds to step S9, where a video signal is created through the output interface section 40, and the video signal for one page is sent to the page printer printing section. Printing of one sheet is completed by the electrophotographic process described above. Furthermore, the process returns to step S4 to obtain data for the next page, and the above-described process is repeated to create pages one after another.

In this way, according to the above embodiment, in an output device that handles "non-dot matrix" fonts and whose RAM capacity can be increased by an expansion board, the "font cache" area is It is now possible to expand using predetermined rules. For this reason, increasing the font cache memory in response to the addition of an optional RAM card has the effect of effectively utilizing the entire RAM space and improving the font cache hit rate. This improves the throughput of the entire device.

The present invention can be modified in various ways without departing from the spirit thereof.

In the above embodiment, the expansion RAM is removable.
Therefore, we propose the following modification example. That is, the built-in RAM in the main body has an area reserved for, for example, a frame buffer for multiple pages and other programs. Therefore, such a spare area may be used as font cache memory. Further, in the above embodiment, a laser beam printer is used as the output device, but the present invention can also be applied to an image output device such as a CRT instead of such a printer.

In addition, although a font using a run-length technique is used as a "non-dot matrix type" font in the embodiment, other so-called outline fonts that memorize contour coordinates, fonts that memorize character strokes,
It can be used in a wide range of "non-dot matrix fonts" such as fonts created by combining radicals of kanji. Furthermore, although the font cache is stored in RAM, it can be easily replaced with other storage media (such as a hard disk).

Although this embodiment has one character generator and uses a single "non-dot matrix" font, it is also possible to have multiple character generators.

Furthermore, in this embodiment, the total R of the font cache memory is
Although the proportion in the AM capacity is fixed at 25%, it is extremely easy to change this proportion by external operation. Also, when no RAM card is installed, 25%, R
When an AM card is installed, it is also meaningful to switch to 20% or the like according to practical use.

It goes without saying that the shape of the RAM card is not limited to board-like, cartridge-like, or IC card-like.

[Effects of the Invention] As explained above, according to the present invention, there are provided a pattern generation means for generating a font pattern such as a character symbol, a first storage means for storing the generated font pattern in a searchable manner as a dot image. , a second storage means which is not normally used for storing font patterns but can be stored as a dot image, and the memory space is dynamically configured such that the second storage means is incorporated into a part of the first storage means. By providing a changing means for changing the font pattern, the space of the first storage means in which the font pattern is to be stored can be increased or decreased as necessary.

In particular, according to the invention of item 2 or 3, the first storage means is built in the font pattern creation device main body,
The second storage means is composed of a memory means that is detachable from the main body, so that even when the second storage means is attached from the outside, the newly added memory is used for storing font patterns.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the inside of a laser beam printer to which the present invention can be applied, FIG. 2 is a memory map explaining an example of the configuration of the printer control unit 101, and FIG. 5 is a diagram for managing font patterns in the embodiment device. FIG. 6 is a flowchart showing the control operation of the CPU in the device of this embodiment. In the figure, 201... host computer, 202... input interface section, 203... input buffer memory,
204...Character pattern generator, 205...RAM
Cartridge, 208...CPU, 209...Frame buffer memory, 210...Output interface unit, 211...Page printer. Patent applicant Canon Inc.

Claims (4)

[Claims] (1) pattern generation means for generating font patterns such as character symbols, first storage means for storing the generated font patterns in a searchable manner as dot images; A font pattern creation device comprising: a second storage means capable of storing dot images; and a changing means for dynamically changing the memory space so that the second storage means is incorporated into a part of the first storage means. . (2) The first storage means is built in the main body of the font pattern creation device, and the second storage means is comprised of a memory means that is removable from the main body. font pattern creation device. (3) The font pattern creation device according to claim 2, wherein the changing means includes determining means for determining whether the memory means is attached to or removed from the main body. (4) The font pattern creation device according to claim 1, wherein the pattern generation means is constructed using a memory method other than a raw pattern dot matrix.