JPH11300996A - Image recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance processing rate of recording data by recording a data while partially overlapping the upper and lower bands of a recording head and distributing a recording data of a plurality of dots in the overlapped recording range to the upper and lower bands. SOLUTION: The recording range of one thermal head, i.e., an upper band, and the recording range of next thermal head, i.e., a lower band, are recorded while being overlapped partially. When a thermal head has 240 dots, 237th through 240th dots in the upper band and 1st through 4th dots in the lower band are recorded while being overlapped. Among 4 dots, the 237th dot is a reference dot and the 238th dot (2nd dot), 239th dot (3rd dot) and 240th dot (4th dot) are distributed to the upper and lower bands.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image recording method. The present invention relates to an image recording method in which recording is performed separately to an upper band and a lower band.

[0002]

2. Description of the Related Art Generally, thermal transfer printers are widely used as output devices such as computers and word processors for reasons such as high recording quality, low noise, low cost, and ease of maintenance.

In such a general thermal transfer printer, a paper is supported in front of a platen, and a thermal head having a plurality of heating elements is mounted on a carriage, and a thermal head is provided between the thermal head and the platen. In a state where the ink ribbon and the paper are sandwiched, the ink ribbon is fed out while the thermal head is reciprocated with the carriage along the platen, and the heating elements of the thermal head are selectively energized based on the recording information. By causing heat to occur, the ink of the ink ribbon is partially transferred to a sheet, and an image such as a desired character is recorded on the sheet.

[0004] In such a thermal transfer printer, the range recorded by one scan of the thermal head and the range recorded by the next scan of the thermal head are too close to each other due to a paper feed error or the like. Therefore, there is a problem that a so-called black line is generated, or conversely, the respective ranges are separated and a so-called white line is generated.

For example, assuming that a basic halftone dot consisting of an N × M dither matrix is a basic cell, this basic cell is shifted so as to be lowered to the right in the scanning direction of the thermal head to perform recording with a screen angle of minus. FIG. 18
As shown in, when the paper feed amount of the recording paper is appropriate,
The interval between the recording range (upper band) by one thermal head scan and the recording range (lower band) by the next thermal head scan is uniform.

However, as shown in FIG. 19, when the paper feed amount of the recording paper is too small, the interval between the upper band and the lower band becomes narrow, and a black line is generated. Also,
As shown in FIG. 20, when the paper feed amount of the recording paper is too large, the interval between the upper band and the lower band becomes wide, and a white line is generated. Such a black line and a white line are also unsightly and greatly affect the quality of a recorded image.

For this reason, conventionally, in order to prevent the occurrence of black lines and white lines, the upper band and the lower band are partially overlapped and recorded.

FIG. 21 schematically shows such a conventional recording method. For example, when there are 240 heating dots of a thermal head, four heating dots, that is,
237th dot, 238th dot, 2
The 39th dot and the 240th dot are superimposed on the first dot, the second dot, the third dot, and the fourth dot of the lower band. Then, the recording data for these four dots is divided into an upper band and a lower band.

Conventionally, in such a case, the upper band and the lower band are arranged for each column while observing the dots in the arrangement direction (column direction) of each heating element of the thermal head in the overlapping recording range (for 4 dots). And the recording data is distributed to the band. That is, as shown in FIG. 17, when print data is present in all four dots in the first column, the first and second two of the four dots are assigned to the upper band, and And the third and fourth two dots are assigned to the lower band. In the second column, the first dot is assigned to the upper band, and the third and fourth two dots are assigned to the lower band. Further, in the third column, the first dot is assigned to the upper band, and the second and fourth dots are assigned to the lower band.

As described above, conventionally, the print data of the dots is appropriately allocated to the upper band and the lower band for each column, and each heating element of the thermal head is driven based on the allocated print data. As a result, recording is performed in the overlapping recording range.

[0011]

However, in the conventional thermal transfer printer, the recording data of the dots is distributed for each column, so that the processing amount of the recording data is extremely large, and the processing speed becomes extremely slow. There is a problem that it is. Therefore, for example, it is necessary to handle a large amount of print data, such as in the case of performing multi-tone printing by controlling the energization time to the heating element of the thermal head and changing the diameter of the print dot. In the case of such recording, there is a problem that the processing of the recording data cannot be performed in time, the recording speed decreases, and high-speed recording cannot be performed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and can significantly increase the processing speed of print data, perform high-speed printing, and prevent the occurrence of black lines and white lines. It is an object of the present invention to provide an image recording method by which a high-quality recorded image can be obtained.

[0013]

According to the present invention, there is provided an image recording method comprising:
The dots in the scanning direction of the print head are sequentially observed, and if there is print data in this dot, a continuous flag is added to the dot. Only when print data is exhausted, continuous dots with the continuous flag are printed. The point is that the data is divided into two groups in the scanning direction of the recording head, and the data is divided into upper and lower bands, respectively.

[0014] By adopting such a method, compared to the case where the print data distribution process is performed for each column as in the conventional case, the method of the print data distribution process is more regulated. And simple,
In addition, the amount of processing can be significantly reduced, and processing can be performed easily and quickly. In addition, even if the distance between the upper band and the lower band is reduced or widened due to a recording paper conveyance error,
Since dots having an appropriate interval are recorded at an appropriate interval in the scanning direction of the recording head, it is possible to prevent a black line or a white line from being generated in the recorded image, and to obtain an extremely high quality recorded image.

According to a second aspect of the present invention, there is provided an image recording method according to the first aspect, wherein the recording is performed such that the screen angle formed by shifting the arrangement of the basic cells is negative right downward. Of the continuous dot recording data divided into two groups in the scanning direction of the recording head, the recording data on the left side in the scanning direction is allocated to the lower band, and the recording data on the right side in the scanning direction is allocated to the upper band. In the case where recording is performed so that the screen angle rises to the right by plus, the recording data on the left side in the scanning direction among the recording data of the continuous dots divided into the two groups is distributed to the upper band. In that the distribution processing is performed so that the recording data on the right side in the scanning direction is distributed to the lower band.

By adopting such a method, even if the paper feed pitch of the recording paper becomes narrow or wide, dots having the correct distance between the recording dots are always mixed in the column direction. Therefore, it is possible to prevent a black line or a white line from being generated in the recorded image.

According to a third aspect of the present invention, there is provided an image recording method according to the first or second aspect, wherein recording of each color is performed based on image information separated into at least three colors of cyan, magenta and yellow. The point is that the data are individually sorted to perform full-color printing.

By employing such a method, a full-color image can be properly recorded in three colors of cyan, magenta and yellow.

A feature of the image recording method according to a fourth aspect is that, in the first or second aspect, monochromatic recording is performed by performing a sorting process on recording data of monochrome image information. is there.

By employing such a method, a monochrome image can be properly recorded.

[0021]

FIG. 1 is a block diagram showing an embodiment of the present invention.
This will be described with reference to FIG.

FIGS. 1 to 16 show an embodiment of an image recording method according to the present invention. In this embodiment, as shown in FIG. (Upper band) and a recording range (lower band) by the scanning of the next thermal head are partially overlapped and recorded. For example, if the thermal head has 240 heating dots, four dots, ie, the 237th, 238th, 239th, and 240th dots of the upper band, and the 1st, 2nd, and 240th dots of the lower band Dot eye, third dot and fourth
It is designed to be recorded by overlapping the dots. Of the four dots, the 237th dot is used as a reference dot, and the 238th dot (the 2nd dot), the 239th dot (the 3rd dot) and the 240th dot (the 4th dot).
Is divided into an upper band and a lower band.

In the present embodiment, while observing dots in the scanning direction (raster direction) of the thermal head,
The dots in the overlap recording range are sorted into an upper band and a lower band.

Next, means for allocating dots in such an overprinting range to an upper band and a lower band will be described.
This will be described with reference to FIGS.

First, as shown in FIG. 2, first, for example, after initializing a memory for storing recording data and other control circuits (ST1), the endmost column to be recorded first in the overlapping recording range An address is set to the dot at (first column) (ST2).

Thereafter, it is determined whether or not the dots in the first column are solid patterns (ST3). The solid pattern refers to a pattern to be recorded at the maximum gradation. When all the dots in the column direction are solid patterns, it is determined that the solid pattern is a solid pattern.

If the dot in the column is a solid pattern, a solid flag is given (ST4), and solid pattern processing is performed (ST5). In this solid pattern processing, as shown in FIG. 3, it is determined whether or not the solid pattern is the first solid pattern (ST6). If the solid pattern is the first solid pattern, each dot in the column direction is set to the maximum gradation. Are assigned to, for example, the upper band (ST7). Of course, this may be allocated to the lower band. If the solid pattern is not the first solid pattern, regular pattern processing is performed (ST8). In this regular pattern processing, as shown in FIG. 5, for example, some of the dots in the column direction are thinned out, and only the dots to be printed are recorded as the dots to be recorded at the maximum gradation. The band is assigned to the upper band (ST9).

Further, as shown in FIG. 2, if the dot of the column is not a solid pattern, the process returns to the previous column to determine whether or not the pattern is a solid pattern (ST10). If is a solid pattern, a return process is performed (ST11). In this return process, as shown in FIG. 4, the solid flag is cleared (ST12), and each dot in the column direction is set as a dot to be recorded at the maximum gradation.
For example, it is assigned to the upper band (ST13). That is, in the range recorded by the solid pattern, all dots are recorded in the first column and the last column of the solid pattern, and thinned dots are recorded in columns between them. The reason why all dots are recorded in the first column and the last column of the solid pattern in this way is, for example, in a rectangular pattern of a solid pattern or the like, so that the stitching processing part of the side is not missing. The reason why the thinned dots are recorded in the intervening column is that if all the dots in the interval are recorded, the recording becomes too dark, and a so-called black line is generated.

If the dot of the column is not a solid pattern, raster processing is performed from the 238th dot (ST14). This raster processing is performed as shown in FIG.
It is checked whether or not there is print data in the dot portion of the 238th dot of the column (ST15).
It is checked whether this recording data is the first recording data (ST1).
6) If it is the first print data, the first address of the continuous data for the dot is stored (ST17), and a continuous flag is given (ST18). If it is not the first recording data, a continuous flag is added as it is (S
T18).

If there is no recording data in the dot portion of the column, the number of continuous flags up to that point is checked.
The recording data is divided into two groups at the center position in the raster direction in accordance with the number of the continuous flags, and a process is performed in which these groups are grouped and the recording data is divided into an upper band and a lower band. At this time, in the present embodiment, it is determined whether or not the continuous flag is an even number (ST
19) If the continuous flag is an even number, an even number process is performed (ST20). If the continuous flag is not an even number, it is determined whether or not it is an odd number (ST21). If the continuous flag is an odd number, an odd number is determined. Processing (ST2).
2).

Whether the two groups divided in the raster direction are recorded in the upper band or the lower band may be arbitrarily selected. In the present embodiment, the dither matrix is used as a unit. In the case where a so-called screen angle is formed by arranging basic halftone dots (basic cells) to be appropriately shifted, the screen angle is determined by whether the screen angle is negative or positive. ing.

For example, when the screen angle is minus right lowering, of the continuous flag groups divided into two, the recording data of the left group is sorted to the lower band, and the recording data of the right group is divided. If the screen angle is positive and rises to the right, the recorded data of the left group will be distributed to the upper band, and the recorded data of the right group will be distributed to the lower band. It is supposed to be sorted.

The reason why the screen angle is formed to be negative or positive is to prevent the occurrence of moire fringes which occur when each ink is superimposed and to stabilize the hue of the recorded image in color recording. .

Here, the even-number processing and the odd-number processing will be described in detail by taking as an example a case where recording is performed so that the screen angle becomes negative right downward.

In the above even-number process, as shown in FIG. 7, first, a value N obtained by dividing the number of continuous flags by 2 is calculated (ST2).
3) Write 0 in the upper band as the recording data of the dot in the column of the first address among the dots to which the continuation flag is added (ST24), and write the recording data in the lower band (ST25). . Next, the address of the column is advanced by one for both the upper band and the lower band (ST26, 27). Similarly, 0 is written to the upper band as dot recording data of the next column (ST24). , Write recording data to the lower band (ST
25), This process is repeated N times (ST28). When this process is repeated N times, the recording data of the dot in the next column is written in the upper band (ST4129), and
0 is written in the lower band (ST30). Next, the address of the column is advanced by one in both the upper band and the lower band (ST31, 32), and similarly, the recording data of the dot in the next column is written in the upper band (S31).
T29), 0 is written in the lower band (ST30), this process is repeated (number of data-N) times (ST33), and the recording data distribution process is performed. As a result, as shown in FIG. 8, the recording data is sorted. Here, “○” indicates that there is recorded data,
“X” indicates that there is no recording data.

Next, the odd number process will be described with reference to FIGS.

When the continuous flag is an odd number, the continuous flag cannot be divided into equal numbers in the left and right directions in the raster direction, and a fractional flag is generated. For this reason, this fractional flag is added to one of the left and right groups, and each recording data is distributed and written to either the upper band or the lower band.

In this embodiment, the raster of the 238th dot is sorted so that a fractional dot is added to the left group. That is, as shown in FIG. 9, a value M obtained by dividing the number obtained by subtracting 1 from the number of continuous flags by 2 is calculated (ST34), and of the dots to which the continuous flag is assigned, As recording data, 0 is written in the upper band (ST35), and recording data is written in the lower band (ST35).
36). Next, the address of the column is advanced by one for both the upper band and the lower band (ST37, ST3).
8) Similarly, 0 is written in the upper band as the recording data of the dot in the next column (ST35), and the recording data is written in the lower band (ST36).
This is repeated twice (ST39). When this process is repeated M times, the recording data of the dot in the next column is written in the upper band (ST40), and 0 is written in the lower band (ST41). Next, the column address is advanced by one for both the upper band and the lower band (ST42, ST42).
43) Similarly, the recording data of the dot in the next column is written in the upper band (ST40), and 0 is written in the lower band (ST41). This process is performed by subtracting M from the number of the continuous flags. The repetition is performed by (the number of data-M) (ST44), so that the recording data distribution process is performed. As a result, the recording data is sorted as shown in FIG.

It should be noted that it is possible to arbitrarily determine to which of the left and right groups one dot of the fractional flag in the odd processing is added. In the present embodiment, the columns at the 238th dot and the 239th dot are added to the left group, and the column at the 240th dot is added to the right group.

As shown in FIG. 6, when there is no recording data in the dot portion of the column and the number of continuous flags is 0, the addresses of the upper and lower bands are stored (S
T45), 0 processing is performed (ST46). In the 0 processing, as shown in FIG. 11, 0 is written in the upper band as the recording data of the dot in the column (ST4).
7) Write 0 in the lower band (ST
48). As a result, as shown in FIG. 12, the recording data is sorted.

Further, when each of the above processes is completed, the continuous flag is cleared (ST49), and the raster process for the 238th dot is completed.

After the recording data of the 238th dot has been distributed in this manner, similarly, as shown in FIG.
While performing the raster processing of the 39th dot (ST5)
0), raster processing for the 240th dot is performed (ST5).
1).

Thereafter, the address is moved to the next column (ST52), and it is determined whether or not the recording data has been distributed to all the columns (ST53). If so, the distribution processing is completed. If not, the sorting process is repeatedly performed on the recording data of all the columns.

By performing such processing, desired recording is performed by operating the thermal head based on the distribution of recording data.

Although the above-described recording data distribution processing has been described for the case where recording is performed so that the screen angle becomes minus right downward, when recording is performed so that the screen angle becomes plus upward right, The recording data allocated to the upper band and the lower band are each allocated to the upside-down band.

More specifically, in the even-number processing and the odd-number processing, when the screen angle is negative, the recording data written in the upper band is written in the lower band, and 0 (no recording data) is written, while the recording data written in the lower band is written in the upper band, and 0 is written in the lower band. As a result, as shown in FIGS. 13 and 14, the recording data is sorted.

Further, for example, by performing recording data distribution processing for each color based on image information for each color of cyan, magenta, and yellow, a full-color image can be properly recorded. In this case, the sorting process of each color may be such that print data is sorted based on the same even process and odd process for each color, or the even process and the odd process are different for each color according to the column. It may be arranged as follows.

Further, based on monochrome image information,
By performing the print data sorting process, a monochrome image can be properly recorded.

Therefore, in the present embodiment, for a dot in the raster direction, if there is print data in this dot, a continuous flag is given to that dot, and only when there is no print data, the continuous flag is given. Since continuous dots are divided into two groups on the left and right, and the recording data is regularly distributed to the upper band and the lower band, a sorting process is performed. Compared to the case of performing the recording data distribution processing, the processing method of the recording data distribution processing is simplified, and the processing amount can be significantly reduced, and the processing can be performed easily and quickly. Can be. As a result, the distribution processing time can be extremely reduced as compared with the conventional case, the recording speed can be increased, and the multi-gradation recording is performed by changing the diameter of the recording dot. Can also respond sufficiently.

Further, as shown in FIG. 15, continuous dots provided with a continuous flag are divided into two groups of right and left, and each recording data is routinely distributed to an upper band and a lower band. Therefore, for example, as shown in FIG. 16, when the screen angle is minus right downward, even if the paper feed pitch becomes narrow, the distance between the recording dots based on the recording data allocated to the lower band is set to the correct distance. As a result, the portion where the distance between the recording dots is small is inconspicuous, and the occurrence of a black line in the recorded image can be prevented.

Conversely, as shown in FIG. 17, even if the paper feed pitch is widened, the distance between the recording dots based on the recording data allocated to the upper band is maintained at the correct distance, and It is possible to prevent a portion having a large distance from being noticeable, and to prevent a white line from being generated in a recorded image.

Further, when recording so that the screen angle becomes minus right lowering, the recording data on the left side among the recording data of the continuous flags divided into the right and left groups is written to the lower band, and the recording data on the right side is written. Write in the upper band, and when recording so that the screen angle rises to the positive right, write the left-side recording data of the continuous flag recording data divided into left and right groups to the upper band. In addition, by writing the right-side recording data to the lower band, it is possible to efficiently perform clear recording with good connection between dots.

It should be noted that the present invention is not limited to the above-described embodiment, and can be changed as needed.

For example, the above-described image recording method has been described as an image recording method in a thermal transfer printer. However, the present invention is not limited to such a case and can be applied to a serial type ink jet printer or the like.

[0055]

According to the first aspect of the present invention, by adopting such a method, it is possible to compare with the conventional case in which the recording data is distributed for each column. Thus, the method of sorting the recording data is regular and simple, and the amount of processing can be significantly reduced, so that the processing can be performed easily and quickly. Further, even when the distance between the upper band and the lower band is narrowed or widened due to a recording paper conveyance error, dots having an appropriate interval in the scanning direction of the recording head are provided. Is recorded, it is possible to prevent a black line or a white line from being generated in a recorded image, and to obtain a very high-quality recorded image.

According to the second aspect of the invention, in addition to the effects of the first aspect, even if the paper feed pitch of the recording paper becomes narrower or wider, the column is always provided. Since the dots having the correct distance between the recording dots are mixed in the direction, it is possible to reliably prevent the occurrence of black lines and white lines in the recorded image.

According to the third aspect of the present invention,
In addition to the effects of the invention described in claim 1 or claim 2,
A full-color image can be properly recorded using three colors of cyan, magenta, and yellow.

Further, the invention described in claim 4 is the same as that in claim 1.
Alternatively, in addition to the effect of the invention described in claim 2, there is an effect that a monochrome image can be properly recorded.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an embodiment of an image recording method according to the present invention.

FIG. 2 is a flowchart showing recording data distribution processing in the image recording method of the present invention.

FIG. 3 is a flowchart showing solid pattern processing in FIG. 2;

FIG. 4 is a flowchart showing a return process in FIG. 2;

FIG. 5 is a flowchart showing a regular pattern process in FIG. 3;

FIG. 6 is a flowchart showing raster processing of the 238th dot in FIG. 2;

FIG. 7 is a flowchart showing processing when the screen angle is negative in the even-number processing in FIG. 6;

FIG. 8 is an explanatory diagram showing a distribution result by the even-number processing in FIG. 7;

FIG. 9 is a flowchart showing processing when the screen angle is negative in the odd number processing in FIG. 6;

FIG. 10 is an explanatory diagram showing a sorting result by the odd-number processing in FIG. 9;

FIG. 11 is a flowchart showing a 0 process in FIG. 6;

FIG. 12 is an explanatory diagram showing a result of sorting by the 0 process in FIG. 11;

13 is an explanatory diagram showing a sorting result by a process when the screen angle is positive in the even-number process in FIG. 6;

FIG. 14 is an explanatory diagram showing a sorting result by a process when the screen angle is positive among the odd-number processes in FIG. 6;

FIG. 15 is an explanatory diagram showing an overlap recording portion of an upper band and a lower band when the paper feed pitch is matched in the image recording method of the present invention.

FIG. 16 is an explanatory diagram showing an overlap recording portion of an upper band and a lower band when the paper feed pitch is narrow in the image recording method of the present invention.

FIG. 17 is an explanatory diagram showing an overlap recording portion of an upper band and a lower band when the paper feed pitch is wide in the image recording method of the present invention.

FIG. 18 is an explanatory diagram showing recording of a boundary portion between an upper band and a lower band when a paper feed pitch is matched in a conventional image recording method.

FIG. 19 is an explanatory diagram showing recording of a boundary portion between an upper band and a lower band when the paper feed pitch is narrow in the image recording method of the present invention.

FIG. 20 is an explanatory diagram showing recording of a boundary portion between an upper band and a lower band when the paper feed pitch is wide in the image recording method of the present invention.

FIG. 21 is an explanatory diagram showing processing when an upper band and a lower band are overlaid and recorded in a conventional image recording method.

Claims (4)

[Claims] 1. A recording sheet is conveyed so that a plurality of dots overlap an upper band which is a recording range by one scanning of a recording head and a lower band which is a recording range by scanning of a next recording head. At the same time, the recording data for a plurality of dots in the overlapping recording range is divided into an upper band and a lower band, and recording is performed by operating each heating element of the recording head based on the divided recording data. In the image recording method, the dots in the scanning direction of the recording head are sequentially observed, and if there is recording data in this dot, a continuous flag is added to the dot. Distributing the recording data of the given continuous dots into two groups in the scanning direction of the recording head and distributing them into upper and lower bands, respectively. An image recording method characterized by performing processing. 2. When printing is performed such that the screen angle formed by shifting the arrangement of the basic cells becomes minus right lowering, continuous dots of continuous dots divided into two groups in the scanning direction of the printing head. Among the recording data, the recording data on the left side in the scanning direction is allocated to the lower band, and the recording data on the right side in the scanning direction is allocated to the upper band, and the recording is performed so that the screen angle is positively increased to the right. When performing, among the recording data of the continuous dots divided into the two groups, the recording data on the left side in the scanning direction is distributed to the upper band,
2. The image recording method according to claim 1, wherein the distribution processing is performed so that recording data on the right side in the scanning direction is distributed to a lower band. 3. A full-color printing by performing a sorting process on print data of each color based on image information color-separated into at least three colors of cyan, magenta and yellow. 3. The image recording method according to claim 1 or 2. 4. The image recording method according to claim 1, wherein a distribution process is performed on recording data of monochrome image information to perform monochrome recording.