JPH1049316A - Image forming device and its host device, and print system including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device which uses a cache memory, etc., efficiently and has a superior use rate (hit rate) with small memory capacity and a print system which includes the device. SOLUTION: A host computer checks the use frequencies and appearance distributions of character codes included in print data in advance, registers character codes which are less in use frequency and appearance distribution than specific values and waste a memory when previously registered in the cache as character codes inhibited from being cached, and registers character codes which are larger in use frequency and appearance distribution than the specific values and high in appearance frequency as character codes inhibited from being deleted. After this previous registration, characters to be registered among characters included in the print data are registered and also registered in a font cache buffer 15 while converted into bit map data, and bit map data registered in the font cache buffer 15 are read out each time a reread is made, thereby performing efficient and fast print processing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, an upper apparatus thereof, and a printing system including the same, and more particularly, to an image forming apparatus which performs efficient printing using outline fonts, and an upper apparatus thereof. Related to printing systems.

[0002]

2. Description of the Related Art When analyzing print information output from a host computer and developing it in an image memory, outline fonts are employed to clearly print images such as characters. However, in the image forming apparatus using the outline font, since it takes time to develop the pattern data from the outline font to the image memory after designating the character, the pattern data of the character used once is stored in the memory (for example, the cache memory). ) Is registered as cache data. By performing such processing, when printing the same character again, the cache memory can be designated, and the pattern data can be directly expanded from the cache memory to the image memory, thus enabling high-speed data expansion processing.

Since the capacity of the cache memory is limited, old and infrequently used data is sequentially updated.
New data is registered.

[0004]

In the above-mentioned conventional apparatus,
Infrequently used characters are always registered in the cache memory. For example, a character that is printed only once is registered in the cache memory. Therefore,
If a large cache memory capacity cannot be secured, the number of characters that can be registered is small, and the utilization rate of the cache memory decreases. That is, the hit rate of the cache memory decreases.

[0005] In addition, this process itself deletes complicated data and new input processing is frequently repeated, so that efficient cache management cannot be performed. SUMMARY OF THE INVENTION In order to solve the above-described problems, an object of the present invention is to provide an image forming apparatus that uses a cache memory efficiently, has a small memory capacity, has an excellent utilization rate (hit rate), and a printing system including the apparatus.

[0006]

According to a first aspect of the present invention, there is provided an analyzing means for analyzing information included in print data, and selecting whether or not a font cache is registered based on an analysis result of the analyzing means. A transfer unit that transfers a selection result of the selection unit to the image forming apparatus;
Conversion means for converting an outline font of a corresponding character into bitmap data based on the data transferred from the transfer means, a cache memory for registering the bitmap data converted by the conversion means in advance, and registration in the cache memory This can be achieved by providing a printing system including an image forming apparatus having printing means for printing on recording paper based on the bitmap data thus obtained.

Here, the analyzing means and the selecting means are connected to the image forming apparatus, for example, a CPU in a host computer.
And a ROM. Based on a program stored in the ROM, the CPU performs print data analysis processing and selection processing of the presence or absence of font cache registration based on the analysis processing.
The selection data indicating whether or not the font cache is registered is transferred to the image forming apparatus by the transfer unit.

Further, when the image forming apparatus performs a printing process based on the print data, the outline font of the corresponding character is converted into bitmap data based on the transfer data and registered in the cache memory. When developing the same data to be bitmap data,
By using this bitmap data, printing processing on recording paper is performed. With this configuration,
Only the characters that need to be registered in the cache memory are preliminarily registered in the cache memory based on the information on whether or not the font cache has been registered by the host device.

A second aspect of the present invention embodies the first aspect of the present invention, wherein the analyzing means analyzes, for example, the number of times of use and appearance distribution of characters included in print data. .

The number of times of use of a character is the number of times of use of the same character included in print data, and the appearance distribution is an interval at which the same character is used. By analyzing the number of uses and the appearance distribution of characters included in the print data, the number of identical characters included in the print data can be known, and the characters that need to be registered can be accurately known. The registration process in the cache memory is performed based on the above, the effective use of the memory can be performed more reliably, and more efficient printing process can be performed.

According to a third aspect of the present invention, the selecting means selects a character whose font cache registration is to be prohibited from, for example, an analysis result of the analyzing means. It is.

For example, from the above analysis result, if a character appears once or very few times in the print data, the font cache registration for the character is prohibited, and even if the character is registered, it is not used or the number of times it is used Prohibit the registration of characters with few characters.

With such a configuration, a cache memory (cache buffer) having a small memory capacity can be used, and the memory utilization rate is improved. The invention according to claim 4 embodies the invention according to claim 1, wherein the selection means selects a character for which font cache registration is to be performed in advance from the analysis result of the analysis means, for example.

For example, from the analysis result, when a certain character appears many times in the print data and its appearance distribution is large, an instruction to register a font cache for the character is output. With this configuration, font cache registration is reliably performed for characters that appear many times and appear, and efficient printing processing is performed. According to a fifth aspect of the present invention, there is provided an analyzing means for analyzing information included in print data, and a selection for selecting a character for which registration of a font cache and prohibition of registration are performed based on an analysis result of the analyzing means. This can be attained by providing a higher-level device having means and a transfer unit for transferring a selection result of the selection unit to the image forming apparatus.

That is, the above invention is an invention of a host device such as a host computer for providing information of registration of a font cache and registration prohibition to an image forming apparatus. The invention according to claim 6 embodies the invention according to claim 5, wherein the analysis unit analyzes, for example, the number of times of use and the appearance distribution of characters included in print data.

That is, the present invention is configured to embody the analyzing means according to the fifth aspect of the present invention, and the analysis includes the number of times of use and appearance distribution of characters included in print data. According to a seventh aspect of the present invention, there is provided a conversion method for converting an outline font of a corresponding character into bitmap data based on character information for registering a font cache transferred from a higher-level device and prohibiting registration. Means, a cache memory for pre-registering the bitmap data converted by the conversion means, and a printing means for printing on recording paper based on the bitmap data registered in the cache memory. Can be achieved.

That is, the above-mentioned invention is an invention of an image forming apparatus in which registration of a font cache and information of prohibition of registration are provided.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 2 is a configuration diagram of the image forming apparatus of this embodiment, its higher-level devices, and a printing system including these devices. In FIG. 1, an image forming apparatus 1 is connected to a host computer 2 as a host device, and includes an interface controller (hereinafter, referred to as an I / F controller) 3 and a printer engine 4. I
/ F controller 3 includes CPU 5, ROM 6, RAM
7, outline vector data 8, a cache control unit 9, and a frame memory 10. CPU5
Performs control processing according to the program stored in the ROM 6 described above. For example, the CPU 5 receives print information supplied from the host computer 2, analyzes the print information, outputs a character code included in the print information to the above-described outline vector data 8, and converts the character code into corresponding pattern data. Then, the data is output to the frame memory 10. The cache control unit 9 converts a part of the vector data registered in the outline vector data 8 into bitmap data, and registers the converted data.

The frame memory 10 has a memory area for storing the above-described pattern data, and stores, for example, video data for one page of paper. On the other hand, the printer engine 4 is an image forming unit that performs actual printing (transfer) on recording paper.
In the case of the electrophotographic image forming apparatus 1, after charging, the above-described video data is output to a print head, and development and transfer processes are performed, and an image is formed on recording paper.

Incidentally, the image forming apparatus 1 and the host computer 2 are connected via a host interface 12, and the I / F controller 3 and the printer engine 4 are connected via a printer interface 13.

FIG. 1 shows a specific configuration of the cache control unit 9 described above. The cache control unit 9 includes a font cache buffer 15, a cache management table 16, a font cache management unit 17, and an outline character drawing unit 1.
8, a buffer 19 for bitmap development. Note that the outline vector data 8 and the frame memory 10 shown in the figure are the circuits described in FIG.

The outline vector data 8 stores data corresponding to a character code in a vector font state.
Each time a character code is input, the corresponding vector font is read and output to the outline character drawing unit 18. The outline character drawing unit 18 converts the vector font into bitmap data, and
Expand to 9. When a registration command described later is input from the host computer 2, the bitmap data created by the outline character drawing unit 18 is registered by the registration processing unit 17 a of the font cache management unit 17 and registered in the font cache buffer 15. . The cache management table 16 stores the font cache buffer 15
Manages the registration area of the bitmap data to be registered in the.

The bitmap data registered in the font cache buffer 15 is output to the bitmap development buffer 19 according to the processing of the read processing unit 17c. The bitmap data expanded in the bitmap expansion buffer 19 is output to the frame memory 10.

When a deletion command described later is input from the host computer 2, the bitmap data registered in the font cache buffer 15 is deleted according to the processing of the deletion processing unit 17b.

The number of characters that can be registered in the above-mentioned font cache buffer 15 is determined by the capacity of the font cache buffer 15 and the character size of print data. That is, the number of characters that can be registered in the font cache buffer 15 = the capacity of the font cache buffer 15 / the capacity per character (character size).

On the other hand, the host computer 2 (FIG. 2)
The CPU 2a) includes a CPU 2a, a ROM 2b, and a RAM 2c, outputs print data, and outputs command information for controlling the cache control unit 9 to the image forming apparatus 1. The command information is created by the host computer 2 based on the print information. This command information is creation information of various commands such as the above-mentioned registration command and deletion command.

The processing operation of the printing system having the above configuration will be described below. First, processing performed on the host computer 2 will be described. This process is a process of creating command information to be output to the image forming apparatus 1. FIG. 3 is a diagram for explaining this processing.
0 is registered in the RAM 2c, for example. The print data may be created by the host computer 2 using word processing software, or may be print data created by another computer or word processor.

The print data is sent to the CPU 2 according to the print character data analysis processing program 21 stored in the ROM 2b.
Analyzed by 2a. This analysis process is a process of analyzing the number of times of use and appearance distribution for each character (each character code) included in the print data, and creating the table 22 in the RAM 2c. The above-mentioned number of times of use is, for example, the number of appearances of the same character included in the print data, and the occurrence distribution is the interval from the use of a certain character to the next use, and therefore, the The smaller the value, the smaller the value. The CPU 2a sequentially analyzes the print data, and analyzes the number of uses and the appearance distribution for each character (for each character code).

FIG. 4 is a flowchart for explaining this analysis processing. FIG. 5 is a diagram showing an initial state of the above-described table 22, and includes a character code, a use count, an appearance distribution,
Are reset to “0”.

First, the character code of the print data is read out character by character (step (hereinafter referred to as S) 1), and it is determined whether or not the character code has already appeared (S2). 22 (S3). For example,
FIG. 6 shows the i-th character “aaaa” from the top in Table 2.
2 shows the state registered. On the other hand, if the same character has already been registered, the table 22 is updated (S4). In this update processing, for example, the area of the number of times of use of the area of the same character code in the table 22 is counted up, and data of, for example, character spacing is written in the area of the appearance distribution. FIG. 7 shows the same character “aaaa” already registered again (second time).
Shows the state of the table 22 in which the registration processing has been performed. still,
In this case, the appearance distribution is obtained by adding the squares of the characters read from the first use to the second use.

The above processing is performed on all the character codes included in the print data, and when the processing on all the character codes is completed, the analysis processing is completed (S5: YES).
The data of the number of times of use and the appearance distribution analyzed in this way are registered in the table 22 in the RAM 2c.

Next, the CPU 2a selects a cache-inhibited character and a cache-registered character according to the cache character selection processing program 23 stored in the ROM 2b. Here, the CPU 2a sets a character used only once as a cache-inhibited character and reads a character code used once from the data registered in the table 22 described above. In addition, a character whose usage count is m or more and whose appearance distribution is n or more is set as a cache registration character, and a corresponding character code is read from the above-described table 22.

The cache-inhibited characters and cache-registered characters thus selected are stored in the area 24 of the RAM 2c.
(See FIG. 3). Thus, area 2
4 are added to the cache control command and transferred to the image forming apparatus 1. For example, the character code for which the cache prohibition is selected is added to the cache prohibition control command, and the character code for which the cache registration is selected is added to the cache registration control command, and transferred to the image forming apparatus 1.

Thereafter, the print data registered in the RAM 2c is transferred to the image forming apparatus 1. Note that these transfer processes are also executed based on the programs 25 and 26 stored in the ROM 2b.

Next, processing in the image forming apparatus 1 will be described. The above-described cache control command and print data are supplied to the image forming apparatus 1. Here, the input process of the cache control command will be described first. The font cache buffer 15 and the cache management table 1
In 6, an initial reset process is performed, and a clear process for the previous process data is performed.

The cache control commands include a cache prohibition control command and a cache registration control command including the corresponding character codes as described above, and are supplied from the host computer 2 via the host I / F 12. The CPU 5 in the image forming apparatus 1 performs a corresponding process according to the input of both commands. That is, the CPU 5 registers the character code added to the cache prohibition control command as, for example, the RAM 7 as a cache prohibition character. Further, the character code added to the cache registration control command is registered in the RAM 7 as a cache registration character.
Then, when the corresponding character code is input thereafter, the registration processing of the corresponding bitmap data in the font cache buffer 15 is prohibited or the registration processing is executed.

After the above processing, the host computer 2
Supplies print data. The print data includes information necessary for printing processing such as shading and inversion in addition to the character code. When the print data is input, the CPU 5
For example, after storing data in a reception buffer in the RAM 7, when a predetermined amount of data is input, the print data is analyzed. This analysis process executes a command corresponding to each command of the print data, and executes a process corresponding to a command such as, for example, shading or inversion. Further, the above-described analysis process also performs a process of converting a character code into corresponding bitmap data.

In particular, FIG.
It is a flowchart shown in FIG. That is, the print data is sequentially analyzed, and when the character code is read, it is determined whether the character code has been registered in the cache (ST1).
Usually, in the first determination, since the cache is not registered (ST1 is N (No)), the bitmap development process is executed (ST2). In this process, vector data corresponding to a character code is read from the outline vector data 8 and converted into bitmap data by the outline character drawing unit 18.

After being developed into bitmap data in this way, it is determined whether this data is a cache registration target character (ST3). This determination can be made by checking whether the character code to be analyzed is included in the registration prohibition character code registered in the RAM 7 as described above. Here, for example, if the analysis target character is not a cache registration target character (ST3 is N), the bitmap development buffer 1
9 immediately registers the developed bitmap data in the frame memory 10 (ST4).

On the other hand, if the character to be analyzed is a character to be registered in the cache (ST3 is Y (yes)), it is determined whether or not no more data is input to the font cache buffer 15 (ST5). That is, when data cannot be input to the font cache buffer 15 any more,
The data registered in the font cache buffer 15 is deleted (ST6). Specifically, the oldest input bitmap data or the least frequently used bitmap data is deleted, and then new bitmap data is registered. Further, in this example, the deletion of registration is prohibited even if the above-mentioned condition is applied to a character code for which registration deletion prohibition is instructed.

In the first determination, the font cache buffer 15 has been cleared beforehand.
The above determination (ST5) is N (No), and in the first flow, the process of registering the bitmap data in the font cache buffer 15 is performed without performing the cache deletion process (ST7). Then, the fact that the bitmap data corresponding to the analysis character code has been registered is recorded in the cache management table 16 (ST8). After registering the bitmap data in the font cache buffer 15 in this way, the bitmap data developed in the outline character drawing unit 18 is developed in the frame memory 10 via the bitmap development buffer 19.

Thereafter, the same processing is performed to sequentially read out character codes, and it is determined whether or not the read out character codes have been registered in the cache (ST1).
If it is not registered (ST1 is N (No)), bitmap expansion processing is executed (ST2), it is determined whether the character is a cache target character (ST3), and it is determined whether or not the font cache buffer 15 has room for registration. After doing (ST5),
The new bitmap data is registered in the font cache buffer 15 (ST7). When there is no room for registration in the font cache buffer 15 (Y in ST5),
The registration is deleted for the character code which is old input data or data of low use frequency and has no instruction to prohibit registration deletion (ST6), and new bitmap data is registered (ST7).

On the other hand, while the above processing is repeated, the same character code in the print data is read out (Y in ST1).
In this case, since the bitmap data corresponding to the same character code has already been registered in the font cache buffer 15, the corresponding bitmap data is read from the font cache buffer 15 without performing the same expansion processing again (ST9). That is, the conversion process to the bitmap data by the outline character drawing unit 18 is as follows.
This is an extremely time-consuming process, and the corresponding bitmap data is directly read from the font cache buffer 15 without performing this process, and is expanded in the frame memory 10. Thereafter, the corresponding character code in the cache management table 16 is updated (ST10).

By repeating the above processing, the RAM
7 are registered as bitmap data in the font cache buffer 15 by being analyzed at least once, and when the same character code is read out thereafter, the character is immediately stored in the frame memory 10. Bitmap data can be expanded. Therefore, hereinafter, the conversion process into the bitmap data for the same character code can be omitted,
Conversion processing can be performed efficiently.

Further, by performing registration prohibition processing on a character code that appears only once in print data, useless processing can be avoided even if the character code is registered in the font cache buffer 15. That is, even if a character code that appears only once is converted to bitmap data by the outline character drawing unit 18, the bitmap data registered in the font cache buffer 15 is not used again, and It is wasted.

In the above-described bitmap data deletion processing (ST6), the font cache buffer 1
5, when there is not enough memory for registering new data, the bitmap data to be deleted is old and infrequently used data, and data corresponding to a character code for which deletion prohibition has been registered as a condition. It cannot be deleted. Therefore, as described above, a character code having a large number of uses and a large appearance distribution is not deleted.

Note that, as described above, the frame memory 10
The bitmap data expanded in the frame memory 1
When the data of one page of the recording paper is expanded to 0, the data is output to the printer engine 4 via the printer I / F 13 described above,
Printing is performed on recording paper according to the bitmap data. In addition, at this time, the bitmap data development processing to the frame memory 10 can be performed extremely efficiently and at high speed as described above, and the printing processing can be performed at high speed.

In the above-described example, the number of times of use for prohibiting registration as bitmap data is one time, but is not limited to one time, and may be a small number of times such as two or three times.

[0049]

As described above, according to the present invention, a character which appears only a small number of times is not registered in the cache, so that even if a font cache buffer having a small memory capacity is used, the bitmap data can be stored in the cache memory. Cache registration can be reliably performed for character codes that require conversion.

Further, it is possible to efficiently use the font cache buffer and prevent waste of memory. Furthermore, when there is no room for registering new data in the font cache buffer, “delete” is data for characters for which the requirement for deletion prohibition is not set. Can be registered as bitmap data.

[Brief description of the drawings]

FIG. 1 is a specific configuration diagram of a cache control unit.

FIG. 2 is a configuration diagram of an image forming apparatus of the embodiment and a printing system including the image forming apparatus.

FIG. 3 is a diagram illustrating a process of creating command information to be output to an image forming apparatus.

FIG. 4 is a flowchart illustrating an analysis process of the present example.

FIG. 5 is a diagram illustrating a configuration of a table.

FIG. 6 is a diagram illustrating a configuration of a table when a character code is registered once.

FIG. 7 is a diagram illustrating a configuration of a table when the same character code is registered twice.

FIG. 8 is a flowchart illustrating outline character drawing processing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Host computer 2a CPU 2b ROM 2c RAM 3 Interface controller 4 Printer engine 5 CPU 6 ROM 7 RAM 8 Outline vector data 9 Cache control unit 10 Frame memory 12 Host interface 13 Printer interface 15 Font cache buffer 16 Cache management table Reference Signs List 17 font cache management unit 17a registration control unit 17b deletion control unit 17c read control unit 18 outline character drawing unit 19 bitmap development buffer 20 print data 21 print character data analysis processing program 22 table 23 cache character selection processing program 24 area 25, 26 programs

Claims (7)

[Claims] An analyzing unit for analyzing information included in the print data; a selecting unit for selecting whether or not to register a font cache based on an analysis result of the analyzing unit; and transferring a selection result of the selecting unit to the image forming apparatus. Transfer means for converting an outline font of a corresponding character into bitmap data based on the data transferred from the transfer means; a cache memory for registering the bitmap data converted by the conversion means in advance; A printing means for printing on recording paper based on the bitmap data registered in the cache memory. 2. The printing system according to claim 1, wherein said analyzing means analyzes the number of times of use and appearance distribution of characters included in the print data. 3. The printing system according to claim 1, wherein the selection unit selects a character whose font cache registration is prohibited from the analysis result of the analysis unit. 4. The printing system according to claim 1, wherein the selection unit selects a character for which font cache registration is to be performed in advance from an analysis result of the analysis unit. 5. An analysis means for analyzing information included in print data, registration of a font cache based on an analysis result of the analysis means,
And a transfer means for transferring a selection result of the selection means to the image forming apparatus. 6. The apparatus according to claim 5, wherein said analyzing means analyzes the number of times of use and appearance distribution of characters included in the print data. 7. Based on character information for registering a font cache transferred from a higher-level device and prohibiting registration,
Conversion means for converting the outline font of the corresponding character into bitmap data; cache memory for pre-registering the bitmap data converted by the conversion means; printing on recording paper based on the bitmap data registered in the cache memory An image forming apparatus comprising: a printing unit that performs printing.