JP3000800B2 - Dot matrix printer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dot matrix type printer which stores bitmap data of characters and figures arbitrarily created by a user and reads out the data by a code signal from a host device. The present invention relates to data registration and reading techniques.

[0002]

2. Description of the Related Art When printing a pattern other than a figure or a character stored in a ROM of a printer as a character set in advance, an individual user creates a necessary pattern from bitmap data, and writes this pattern into the printer. It is required to register as external character data in the memory device.

Incidentally, such registration of external character data is normally performed by allocating a part of a memory device constituting a buffer or the like built in a printer, but there is a possibility that the character data is registered. It is necessary to secure a capacity corresponding to the data size of the maximum size.

[0004]

However, the degree of necessity of external characters varies depending on the user, and there is little need for external characters for some users. In this case, one of the memory devices for registering external character data is used. There is a problem that parts are wasted.

A method of compressing bitmap data constituting an external character pattern to reduce the amount of memory required for storing data is used on a maker side for a printer built-in character pattern and the like. Requires specialized knowledge and cannot be immediately applied to user registration of external character data.

The present invention has been made in view of such a problem, and an object thereof is to convert external character data created by a user into compressed data without forcing the user to perform a compression operation. It is an object of the present invention to provide a dot matrix type printer which can be registered from the Internet and can effectively utilize the memory.

[0007]

SUMMARY OF THE INVENTION The present invention provides a compression means for compressing bitmap data by a plurality of methods, respectively, and receiving the compressed data from the compression means by a plurality of compression methods to minimize the data amount. A dot comprising: a selection unit that selects compressed data by a compression method; a storage unit that stores the compressed data selected by the selection unit; and a restoration unit that reads out the compressed data from the storage unit and restores the data to bitmap data. Provide a matrix type printer.

[0008]

The bitmap data is compressed by a plurality of methods. The data amounts of the data respectively generated by the compression by the plurality of methods are compared, and the compressed data by the compression method with the smallest data amount is selected and stored in the storage means. Thus, the external character pattern data created by the user can be automatically stored in the storage unit in a compressed form that minimizes the data amount, so that the printer memory can be effectively used.

[0009]

FIG. 1 is a block diagram showing the configuration of one embodiment of the present invention. Reference numeral 1 denotes a control device constituted by a microcomputer, and signals from a host device via an interface 2, such as external character data and control signals. To receive commands. The control device 1 has a memory 4 storing a control program for controlling a function as a printer.
Also, a storage device 5 including a ROM and a working RAM for storing bitmap data of characters and patterns prepared as defaults is connected. Further, a driver 7 for outputting bitmap data to the print head 8 is connected to the control device 1 via the interface 6.

FIG. 2 is a block diagram showing functions to be performed by a microcomputer constituting the control device 1 described above. The data analysis unit 10 analyzes a signal input from the host device, and outputs external character data, a memory address signal,
It outputs memory selection and control signals.

The address signal output from the data analyzer 10 is given to the RAM 17 and the ROM 16 in which a default font is registered in advance for address designation. The selection signal and the control signal from the data analyzer 10 are: In order to select the ROM 16 and the RAM 17 and control the write / read operation, the ROM 16 and the RA
M17.

The external character data output from the data analyzer 10 is input to a bitmap data generator 11. The bitmap data creation unit 11 has a buffer memory, creates bitmap data according to external character data, and develops the bitmap data on the XY coordinate area of the buffer memory. The bitmap data developed in the buffer memory of the bitmap data creation unit 11 is read by the null string removal unit 12. The null column removing unit 12 includes, in the bitmap data (for example, FIG. 4), data that are continuously arranged in a line in the arrangement direction (vertical direction in FIG. 4) of the dot forming elements (for example, print pins) of the print head 8. All data of a group (hereinafter referred to as a data string) is dot-free (that is, null).
(Hereinafter referred to as null data), and if there is a data string in which all data is null data (hereinafter referred to as null string), this is deleted (this is referred to as pre-compression processing). ). The bitmap data after the pre-compression processing output from the null string removing unit 12 is used for the compression unit 1 having a plurality of compression modes.
3 is input. The compression unit 13 compresses the bitmap data after the pre-compression in a plurality of compression modes.
Bitmap data compressed in each compression mode (hereinafter, referred to as compressed data) is sent to the comparing unit 14 together with uncompressed pre-compressed bitmap data (hereinafter, referred to as uncompressed data). The data amount of the uncompressed data is compared, and the compressed data or the uncompressed data having the smallest data amount is selected. The data selected by the comparison unit 14 is stored in the registration unit 1
5 together with half information, left space information, right space information and compression mode information to be described later.
17 is written.

The data read from the ROM 16 or the RAM 17 is input to a compression mode determination unit 18 where it is identified which compression mode the data is compressed in or not, and the compression mode determination unit 18 The ROM 16 or the RAM 17 stores the identification result in one of the decompression modules 19a to 19d in the corresponding compression decompression unit 19.
Gives the data read from The compression / decompression unit 19 calculates R
For the data from the AM 17, the compressed data is restored to bitmap data after pre-compression based on data such as half information, left space information, right space information, and compression mode information. Then, the bitmap data output from the compression / decompression unit 19 is input to a null sequence decompression unit 20, where the null sequence removed by the null sequence removal unit 12 is added and restored to the original bitmap data. Then, it is sent to the interface 6 and printing is performed.

In such a configuration, when a request for registration of an external character is received from the host device, the data analysis unit 10 recognizes the request, and the RAM 1 is received by the selection signal.
7 is enabled, the external character data from the host device is compressed in the optimum form as described above, and the compressed data is provided to the RAM 17 as data, and at the same time, the address is specified in the RAM 17 by an address signal, and The control signal causes the RAM 17 to perform a write operation, whereby the compressed data of the external character and the above-described accompanying information are registered in the RAM 17. In this case, the details of the processing performed on the external character data are as follows.

First, the creation unit 11 converts the external character data input from the host device into bitmap data representing a dot pattern. Subsequently, the bitmap data is sent to the null string removing unit 12, where the null string is removed (pre-compression processing). The operation is as follows. The number of consecutive null columns from the left end of the bitmap data is counted, the number of the columns is used as left-side null information, and null columns that are consecutive from the left end by the number of columns are deleted. Next, as half information, it is checked whether or not there is a null column every other column throughout the remaining bitmap data. If there is no null column every other column, the half flag is turned off. If a null row exists every other row, the half-present flag is turned ON. Next, the number of consecutive null columns from the right end is counted, the number of the columns is used as right null information, and null columns consecutive from the right end are deleted by the number of columns. And the flag with half is O
In the case of N, that is, when there is a null column every other column, the null column every other column is deleted. When the flag with half is OFF, no further null row is deleted.
When the pre-compression process is completed, the number of bytes of the bitmap data is calculated.

Subsequently, the compression unit 13 further compresses the bitmap data after the pre-compression processing. In this embodiment, three compression modes will be described. The operation of each mode is as follows.

First compression section (first compression mode) 13a
Checks whether the pattern is symmetrical with respect to the vertical center line when looking at the entire bitmap data after pre-compression, and if so, splits the data to the left and right at the center line Then, only data on one side from the center line is left.

Second compression section (second compression mode) 13b
Is an exclusive-OR operation between adjacent left and right data bytes (a data group constituting one byte in the data string, for example, in FIG. 4, the upper half and the lower half of the data string are respectively data bytes). Check its identity. If the left and right adjacent data bytes are the same, one (eg, right) data byte is deleted, and if different, both bytes are left.

Third compression section (third compression mode) 13c
Determines whether there is a data byte consisting of only null data (hereinafter referred to as null byte) without determining the symmetry or the identity of adjacent data bytes, and deletes the null byte if there is one And keep other data.

After performing such compression, the data amount of the compressed data in each compression mode is calculated, and the comparison unit 14 compares the data amount of each compressed data including the case where no compression is performed, and , The compression mode having the least amount of data is determined to be the optimal compression mode. The compressed data compressed in the optimal mode is sent to the registration unit 15 together with the accompanying half information, left null information, right null information, compression mode information, etc.
7 is registered.

FIG. 3 shows the structure of a memory area assigned to one external character in the RAM 17. The sub address 0 stores half information, the left null information, the right null information, the compression mode information, and the compression mode information. Deleted byte information is stored in the areas from the sub-addresses 4 to m. The deleted byte information indicates the address of the data byte deleted by the optimal compression mode. Each bit of this memory area corresponds to each byte address in the bitmap data, and the address of the deleted byte Is written to the bit corresponding to. Compressed data is stored in the subaddresses m + 1 to n.

When printing external characters registered in such an order, first, the data analysis unit 10 which has received a request for external character printing from the host device supplies a selection signal, an address signal, and a control signal to the RAM 17, and the RAM 17 receives the request signal. The registered external character compressed data and the associated half information, left null information, right null information, compression mode information, and other information are read and sent to the compression mode determination unit 18. Upon receiving the transmitted information, the compression mode determination unit 18 transmits the external character data to the decompression module corresponding to the optimal compression mode. That is, external character data is sent to the first compression / decompression unit 19a when compressed in the first compression mode and to the second compression / decompression unit 19b when compressed in the second compression mode. After the restoration is performed by the restoration unit 19,
The restored data is sent to the null string restoring unit 20, where the null string is restored based on the half information, left null information and right null information, and the original bitmap data is reproduced and printed. You.

The above operation will be specifically described using the bit map data of FIG. 4 as an example.

Eliminating null strings before compression (pre-compression)
The flow of this operation is shown in FIG. First, the number of null columns on the left side is checked. In this case, since the columns “A” and “B” are null columns on the left side, this column number 2 is registered as null information on the left side, and these two columns are deleted. . Next, it is checked whether there is a null column every other column in order from the right side. In this case, “d”, “b”,
.., "F" and "D" are present, so the half-present flag is ON. Next, the rightmost null strings “e” and “d” are detected, and the number of columns 2 is registered as right null information, and the two null strings are deleted.
Furthermore, since the flag with half is ON, 1
Remove null columns that exist every other column. By such a procedure, all null strings are deleted, and bitmap data as shown in FIG. 6 is obtained. In this bitmap data, since half of one data string corresponds to one byte, the data amount of this bitmap data is 28 bytes. Here, the upper data byte is given an even byte address, and the lower data byte is given an odd byte address.

Subsequently, the data shown in FIG. First, the first compression mode will be described. The flow of this operation is shown in the flowchart of FIG. FIG. 8 shows the state of compression. First, the entire pattern is checked to determine whether it is symmetric with respect to the center line.
And a symmetric flag indicating that it is symmetric is set. Then, only the data on one side (for example, the left side) is extracted, and the data amount is calculated. If not symmetric, this compression mode does not compress. The hatched portion in FIG. 8 is a data byte deleted by compression. In this case, since the data amount before compression was 28 bytes, it is 14 bytes which is half of the data amount after compression.

Next, the second compression mode will be described.
The flow of this operation is shown in the flowchart of FIG.
FIG. 10 shows the state of compression. First of all, 2
Compare two data bytes and check if they are identical. If they are the same, one data byte is deleted. If they are not the same, the process proceeds to the next column and the two adjacent data bytes are compared. This is done for all adjacent sets of data bytes.
In this case, when viewed from the left side in FIG. 10, the bytes at addresses 0, 2, 4, 6, and 8 are not identical because their neighbors are not the same. Then, since the addresses 8 and 10 are the same, the 10th byte is deleted.
When the numbers are compared with the twelfth, they are not the same, so they are left as they are. Then, comparing the twelfth and the fourteenth, since they are the same, the fourteenth byte is deleted. As a result of continuing this operation, the bytes indicated by hatching in FIG. 10 are deleted. In this case, the data amount after compression is 22 bytes since it is reduced by 6 bytes from the original data amount.

Next, the third compression will be described. As shown in the flowchart of FIG. 11, this operation flow deletes the byte when all the bits of the byte are spaces, and performs this for all the bytes. In this case, in FIG. 12, all the bits are spaces only in the 7th and 21st bytes of the address, so these 2 bytes are deleted. The data amount after compression is 26 bytes since only the data amount before compression is reduced by 2 bytes.

When comparing the data amount after performing the first, second and third compression modes described above and the data amount of uncompressed data, since the data amount in the first compression mode is the smallest, this mode is used. Is compressed by RA
It will be registered in M17.

In this embodiment, the optimum compression method is selected from the three types of compression methods. However, other compression methods, for example, the pattern similarity between data bytes separated by one byte are determined. If the same pattern continues over 3 bytes or more, a compression method that uses the first byte and the number of bytes of the same pattern as compressed data can be appropriately adopted.

[0030]

As described above, according to the present invention,
Just by creating bitmap data in the same procedure as that for creating an external character, the data is automatically compressed in an optimal compression form and registered in the memory, so that the memory capacity can be used effectively.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic overall configuration of an embodiment according to the present invention.

FIG. 2 is a block diagram showing functions of the control device of the embodiment.

FIG. 3 is a diagram showing a structure of an area of a RAM in which external characters are registered according to the embodiment;

FIG. 4 is a view showing an example of bitmap data used for explaining the operation of the embodiment;

FIG. 5 is a flowchart showing a pre-compression step of the embodiment.

FIG. 6 is a diagram showing an example of bitmap data after pre-compression according to the embodiment.

FIG. 7 is a flowchart showing steps in a first compression mode of the embodiment.

FIG. 8 is a view showing a state of a first compression according to the embodiment;

FIG. 9 is a flowchart showing steps in a second compression mode according to the embodiment.

FIG. 10 is a diagram showing a state of a second compression according to the embodiment.

FIG. 11 is a flowchart showing steps of a third compression mode of the embodiment.

FIG. 12 is a diagram showing a state of a third compression according to the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Data analysis part 11 Bit map preparation part 12 Null string removal part 13 Compression part 14 Comparison part 15 Registration part 16 ROM 17 RAM 18 Compression form determination part 19 Compression restoration part 20 Null string restoration part

──────────────────────────────────────────────────の Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B41J 5/44 B41J 2/485 B41J 5/30 G06F 3/12 H04N 1/21 H04N 1/411

Claims (3)

(57) [Claims] 1. When a request for registering an external character is made,
The external character bitmap data is input, and the external character bitmap data is input.
Null data that satisfies specified conditions is removed from map data
Pre-compression to generate pre-compression bitmap data
And means, receiving said pre-compressed bit map data, the pre-pressure
Compresses compressed bitmap data using multiple compression methods
Main compression means for generating data, wherein when the entire pre-compressed bitmap data is viewed,
Whether the pattern is symmetrical about the vertical centerline
Check, and if it is the target,
Compressed data obtained by dividing the compressed bitmap data to the left and right, leaving only data on one side from the center line
Generating a, a first compression means, the data for the left and right adjacent said pre-compressed bit map data
Check the identity of the columns and check that the adjacent left and right data columns
If they are the same, compression leaving only one data string
A main compression unit having at least a second compression unit for generating data, and receiving compressed data from the main compression unit by a plurality of compression methods, and selecting compressed data by a compression method that minimizes the data amount. Selecting means, storing means for storing the compressed data selected by the selecting means, and printing the compressed data of the external character stored in the storing means
A dot matrix type printer comprising: a decompression means for reading out compressed data from the storage means and decompressing it into bitmap data when requested . 2. The dot matrix type printer according to claim 1, wherein said main compression means includes a pre-compression bitmap data.
The pre-compressed bitmap data
Check if there is data, and if the null data is
In some cases, compressed data from which only null data has been deleted
And a third main compression means for generating data.
Matrix printer. 3. The dot matrix type printer according to claim 1, wherein said pre-compression means is configured to continuously execute the character from the left end in the bitmap data of the external character.
Null data sequence and null data sequence that continues from the right end
And delete null data every other column in the deleted bitmap data.
If there is a data column, this alternate null data
Dot matrix printer that deletes data rows .