JP2001121752A - Printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printer in which shift at a joint can be made inconspicuous when an image is separated while overlapping the joint or when the image is shifted in the horizontal scanning direction at the joint. SOLUTION: The serial printer comprises a print head 8 having a plurality of recording elements, a print control circuit 5, a carriage motor 1, a sheet feed motor 2, a motor drive circuit 3, and a control section 4 for the print control circuit 5 and the motor drive circuit 3 wherein recording is performed by scanning a recording medium relatively in the vertical scanning direction such that the images are overlapped partially between horizontal scanning and next horizontal scanning thereby joining print areas. The control section 4 controls the print control circuit 5 and the motor drive circuit 3 such that the mask pattern of overlapped images is asymmetric at the overlapped part of horizontal scanning and next horizontal scanning.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a serial printing method for printing a desired image or character on a recording sheet by repeating a series of operations of scanning a print head in a main scanning direction and then performing a line feed in a sub-scanning direction. The present invention relates to a printing device such as a printer, a facsimile, a copying machine, and the like.

[0002]

2. Description of the Related Art A serial printer as an example of a printing apparatus has been widely used as a printing apparatus for a personal printer or a word processor because of its relatively simple structure, small size and low price. As recording heads (printing heads), there are a dot impact head, a thermal head, an ink jet head, and the like, which are used in a form that can make use of the characteristics of each head.

FIG. 5A is a configuration diagram showing a general serial printer, and FIG. 5B is a plan view showing a print head of the serial printer shown in FIG.

In FIG. 5, reference numeral 11 denotes a print head, 12 denotes a carriage, 13 denotes a guide, 14 denotes a platen, 15 denotes a recording sheet as a recording medium, and 16 denotes a print area (print band). As shown in FIG. 5B, the print head 11 is formed with n print elements, which are recording elements, in a row.

Next, printing will be described. In the serial printing device, the print head 11 is moved in the X direction, that is, the main scanning direction (a direction perpendicular to the feeding direction of the recording paper 15).
During the movement, the serial dot printing elements (# 1 in FIG. 5B)
To #n) are selectively turned on / off in the printing area 16.
Is printed. Normally, the length H of the serial dot print element arranged in the sub-scanning direction is the width of the print area 16 and is called the print band width. Therefore, in the serial printing apparatus, after the print head 11 moves in the main scanning direction and finishes printing with the print bandwidth H, the recording paper 15 is fed by the print bandwidth H in the sub-scan direction (Y direction). The data of a predetermined area is recorded while repeating the sequence of the print head 11 executing the printing operation again as described above.

Next, the operation of the conventional printing apparatus will be described with reference to FIGS. FIG. 6 (a) shows that the printing band overlaps and separates in the sub-scanning direction (hereinafter simply referred to as
6 (b) is a print state diagram showing a case where an overlap occurs at the joining portion of the print bands, and FIG. 6 (c) is a print band diagram showing a case where an overlap occurs at the joining portion of the print bands. FIG. 6D is a printing state diagram showing a case where separation occurs in the joining portion of FIG. 6, FIG. 6D is a printing state diagram showing a case where the printing band overlaps and the main scanning direction shifts, and FIG. FIG. 11 is a printing state diagram showing a case where a separation occurs in a joining portion of a printing band and a shift occurs in a main scanning direction. FIG. 7A is a printing state diagram showing an upper printing band and a lower printing band, and FIG. 7B is a printing state diagram showing a case where the printing band overlaps a joining portion of the printing band and no separation occurs. FIG. 7C is a printing state diagram showing a case where a separation occurs at the joining portion of the printing band, and FIG.
FIG. 7D is a printing state diagram showing a case where an overlap occurs at the joining portion of the print band, and FIG. 7E is a printing state diagram showing a case where the overlapping portion of the print band and a shift in the main scanning direction occur. is there. In FIG. 7, 20 is an upper band, 30 is a lower band, and W is an overlapping portion (joining portion).

[0007] In a conventional printing apparatus, FIG.
As shown in (c), the first print pattern and the second print pattern, the (n-1) th print pattern and n
As in the case of the second printing pattern, a joining portion of the printing band is required for each printing band width H. in this case,
Since the joining portions of the print bands are all in a straight flat state, for example, as shown in FIG.
There is no problem when printing is performed without separation. However, when the ends of the joining portion overlap or separate from each other, the joining portion of the print band becomes extremely noticeable,
This was the cause of poor print quality. FIG. 6B shows black streaks when the joined portions overlap by １ ／ dot width, and FIG. 6C shows white streaks when the joined portions are separated by ４ dot width. Such phenomena are caused by print head manufacturing accuracy (print element position, shape, etc.), recording paper feeding accuracy, device assembly accuracy, and environmental conditions (temperature, humidity, etc.).
It is a problem that is difficult to solve due to various factors.

On the other hand, the recording area of the joining portion is overlapped by at least one dot, and the overlapping area is selectively recorded so as to be complementary by a conversion table (for example, see Japanese Patent Publication No. 6-35191). 6 (b) and 6 (c) are effective to some extent, but FIG.
In the cases of (d) and (e), no effect can be expected. In addition, the phenomena shown in FIGS. 6D and 6E occur quite generally.

Here, a method of overlapping the joining portions when using a complementary mask pattern will be described with reference to FIG. In this case, for the four overlapping dots, as the complementary mask pattern, 80
An example is shown in which masks are set to be%, 60%, 40%, and 20%. That is, the upper band 20
In the # (n-3) th dot of the overlapping portion of # and the # 4 dot of the overlapping portion of the lower band, 80%, that is, only one dot in a continuous block of 5 dots is not printed. Similarly, # (n-
2) For the dot # 3 and the dot # 3 of the lower band 30,
In order to avoid hitting two dots in a dot block, three dots in a five-dot block are used in the # (n-1) th dot in the overlapping portion of the upper band and the # 2 dot in the lower band. The mask pattern is set so that no dot is hit at the #n dot in the overlapping portion of the upper band and at the # 1 dot of the lower band so as not to hit 4 dots in the 5-dot block. are doing. In the case of the complementary mask pattern, the dots of the lower band 30 corresponding to the positions where the dots of the upper band 20 are not hit (the positions where the dots are OFF) are as follows:
It is the place where dots are to be placed (the place where dots are ON), and conversely the place where the dots of the upper band 20 are to be placed (places where dots are ON)
The dot of the lower band 30 corresponding to is a place where no dot is formed (a place where the dot is OFF). FIG. 7B shows a case where there is no displacement at the joint portion, and FIG. 7C shows a case where a separation in the 1/4 dot sub-scanning direction occurs in the complementary selected pixel mask. 7) shows a case where an overlap in the 1/4 dot sub-scanning direction occurs, and FIG. 7E shows a case where a shift in the 1/4 pixel main scanning direction occurs in addition to the case of FIG. 7D. I have. In the complementary selection pixel mask, especially FIG.
In the case of (e), it is insufficient.

[0010]

As described above, the conventional printing apparatus has a problem that when a shift in the main scanning direction occurs at a joint portion of the print band, the shift is conspicuous at the joint portion. I was

In this printing apparatus, when the print band overlaps and is separated from the printed band, the displacement of the joined portion is inconspicuous, and even if the printed band is displaced in the main scanning direction, the joined portion is displaced. It is required that the deviation be inconspicuous.

According to the present invention, when the print band overlaps and is separated from the printed band, the displacement of the bonded portion can be made inconspicuous, and the printed band can be displaced in the main scanning direction. It is an object of the present invention to provide a printing device that can make the displacement of the joining portion inconspicuous even when the printing is performed.

[0013]

In order to solve the above-mentioned problems, a printing apparatus according to the present invention mainly includes a print head having a plurality of recording elements, a print control circuit for controlling the drive timing of the print head, and a print head. A carriage motor that drives in the scanning direction, a paper feed motor that drives the recording medium in the sub-scanning direction, a motor drive circuit that drives the carriage motor and the paper feed motor, and a control that controls the print control circuit and the motor drive circuit The print head is driven by a print control circuit in accordance with print data, and is scanned in a main scanning direction by a carriage motor to perform one line of recording, thereby performing a main scan and a main scan following the main scan. A serial printing method that prints by connecting the printing areas by relatively scanning the recording medium in the sub-scanning direction so that a part of the image overlaps with the next main scanning that is the scanning. A device, the control unit, the mask pattern of the overlapping image is a structure for controlling the print control circuit and the motor drive circuit so that the asymmetric overlap the main scanning and the next main scanning.

[0014] With this arrangement, when the print band overlaps with the joining portion and the separation occurs, the displacement of the joining portion can be made inconspicuous, and the joining portion of the print band shifts in the main scanning direction. Even in this case, a printing device can be obtained in which the displacement of the joining portion can be made inconspicuous.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A printing apparatus according to a first aspect of the present invention includes a print head having a plurality of recording elements, a print control circuit for controlling a drive timing of the print head, and a print head in a main scanning direction. A carriage motor for driving, a paper feed motor for driving the recording medium in the sub-scanning direction, a motor drive circuit for driving the carriage motor and the paper feed motor, and a control unit for controlling the print control circuit and the motor drive circuit. A carriage is driven in a main scanning direction by a carriage motor while a print head is driven by a print control circuit in accordance with print data, thereby recording one line, and is a main scan and a main scan next to the main scan. A serial printing device that performs printing by connecting printing areas by relatively scanning the recording medium in the sub-scanning direction so that a part of the image overlaps with the next main scanning, Control unit is obtained by the fact that the mask pattern of overlapping images to control the printing control circuit and the motor drive circuit so that the asymmetric overlap the main scanning and the next main scanning.

With this configuration, even if a shift occurs in the overlapping portion between the print band of the main scan and the print band of the next main scan, the print is performed so that the shift is inconspicuous due to the asymmetry of the mask pattern. In addition to the overlapping and separation of the joining portions in the sub-scanning direction, the displacement of the joining portion of the print band in the main scanning direction is less noticeable.

According to a second aspect of the present invention, in the printing apparatus of the first aspect, the control unit makes the mask pattern asymmetrical according to the density of the overlapping portion of the image.

With this configuration, dots are turned on (there is a dot) in a portion having a high density with respect to a shift between the main scanning and the sub-scanning.
To prevent white spots from occurring, and to increase the number of dot OFF (no dot) locations in low-density portions so that dots do not overlap or thicken, thereby deteriorating the image quality of the print band junction. It has the effect that it can be prevented.

According to a third aspect of the present invention, in the printing apparatus of the first aspect, the control unit makes the mask pattern asymmetrical by the dot pattern of the overlapping portion of the image.

According to this configuration, with respect to the deviation between the main scanning and the sub-scanning, the number of the dots ON in the portion where the dot density is high in the overlapping portion is increased to prevent the occurrence of white spots, and in the portion where the dot density is low, This has the effect of increasing the number of dot-off locations so that dots do not overlap or thicken, so that the image quality of the joined portion can be maintained.

According to a fourth aspect of the present invention, in the printing apparatus according to the first aspect, a memory for storing an asymmetric mask pattern in a table is provided, and the control unit refers to the table to make the mask pattern asymmetric. It is decided to do.

According to this configuration, by preparing a plurality of asymmetric mask patterns in advance, it is possible to maintain the image quality at the junction of the print bands at a high speed.

According to a fifth aspect of the present invention, in the printing apparatus of the first aspect, the control unit determines that only one of the overlapping main scans is an asymmetric mask pattern. is there.

According to this configuration, an asymmetric mask pattern of only one of the upper and lower print bands is generated to maintain the image quality of the joined portion of the print bands, so that the processing time for generating the mask pattern is reduced. Also, having only an asymmetric mask pattern of only one band in the table has the effect of reducing the amount of memory by half.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG.

(Embodiment 1) FIG. 1 is a block diagram showing a printing apparatus according to Embodiment 1 of the present invention.

In FIG. 1, 1 is a carriage motor, 2
Denotes a paper feed motor, 3 denotes a motor drive circuit for driving the carriage motor 1 and the paper feed motor 2, 4 denotes a control unit (CPU) for controlling a print sequence of the printer, 5 denotes drive timing of a print head 8 described later, and the like. , A mask circuit for inputting print data a and adjusting a mask pattern at a joint portion of a print band, and 7 for storing a mask pattern to be referred to by the mask circuit 6 and data for determining a mask pattern. The memory 8 has n print elements (recording elements) # 1, # 2,.
The print heads are arranged as # (n-1) and #n. The print head 8 corresponds to the print head 11 in FIG.

With respect to the printing apparatus configured as described above,
The operation will be described with reference to FIGS. FIG. 2A is a printing state diagram showing an upper printing band and a lower printing band, and FIG. 2B is a printing state diagram showing a case where the printing band overlaps a joining portion of the printing band and no separation occurs, and FIG. FIG. 2) is a printing state diagram showing a case where separation occurs at the joining portion of the printing band, FIG.
FIG. 2D is a printing state diagram showing a case where an overlap occurs at the joining portion of the print band, and FIG. 2E is a printing state diagram showing a case where the overlapping portion of the print band and a shift in the main scanning direction occur. is there. FIG. 3 is a flowchart showing an asymmetric mask pattern generation process based on density according to the first embodiment of the present invention, and FIG. 4 is a flowchart showing an asymmetric mask pattern generation process using a pattern according to the first embodiment of the present invention.

In FIG. 2, 20 is an upper band, 30 is a lower band, and W is an overlapping portion (joining portion).

In FIG. 2, the number of overlapping pixels in the joint portion W should be suitably set according to the print head, the printing method, the resolution, and the like. Here, the case where four dots overlap will be described. That is, upper band 2
0 and the lower band 30 correspond to one main scan, and the overlapping portion W of the upper band 20 is the print element # (n-3), # (n-2), # (n-
1), #n, and the overlapping portion W of the lower band 30 corresponds to the print elements # 1, # 2, # 3, # 4 of the print head 8. As in the case of FIG. 7, the overlapping portion W is for four dots, and the basic mask pattern is based on the same one in terms of comparison with FIG. The asymmetrical portion is indicated by oblique lines (a straight line from the upper left to the lower right in the circle), and is a dot ON position in both the upper band 20 and the lower band 30. The non-complementary, ie, asymmetric, mask pattern needs to be adjusted according to the characteristics of the print head 8 and the shape of the dots. As a criterion for determining the mask pattern, there may be a case where the density of the bonding portion W is used as a criterion. In an extreme case, even in the case of hitting twice, the portion having a high density can be made inconspicuous without adversely affecting the displacement occurring at the joining portion W of the print band. In the low-density portion, by setting the dot-off portions in both the upper band 20 and the lower band 30, the overlapping of dots and the thickening due to the combination of dots are made inconspicuous, and the image quality is degraded even when there is no shift. Do not feel.

The flow of processing for generating an asymmetric mask pattern based on density and performing mask processing for an overlapping portion will be described with reference to the flowchart of FIG.

In FIG. 3, first, for all the overlapping pixels, the shade is determined using the adjacent pixels (S).
1). Next, an average density D is obtained using adjacent pixels including the target dot (S2). The adjacent pixels are eight dots vertically, horizontally, and diagonally. At the end points, the average density D can be obtained by using only available pixels. Next, a density threshold value TH1 is obtained based on the pattern of adjacent pixels, the number of dots serving as a dot ON mask pattern, and the like (S3). A method of determining the value of the threshold value TH1 depending on the characteristics of the printer or the like, writing the value in a table in advance, and referring to the value is also available. Here, it is determined whether the target dot is a dot ON or a dot OFF (S4). If it is a dot OFF dot, it is determined whether the dot is ON based on the average density D and the density threshold TH1 (S5, S6). Conversely, if the dot is a dot ON, it is determined whether or not the dot is OFF based on the average density D and the density threshold value TH1 (S7, S8). A series of these processes is performed on all the overlapping pixels, and the overlapping portion W is masked using the generated mask pattern (S9). Here, an example in which the density is determined using only the dots adjacent to the target dot is described. However, a method of determining the density using a pixel at the junction end including the maximum, overlapping portion or overlapping portion is also possible. is there.

Similarly, a similar effect can be obtained by forming an asymmetric mask pattern by the dot pattern of the overlapping portion W. A flow of a process of generating an asymmetric mask pattern based on the dot pattern of the overlapping portion W and performing a mask process on the overlapping portion W will be described with reference to the flowchart of FIG.

In FIG. 4, first, a pattern is determined for all overlapping pixels by using neighboring pixels (S11). Next, a dot pattern of a neighboring pixel including the dot of interest (hereinafter, referred to as “neighboring pixel pattern”) is obtained (S12). Various methods are possible, such as setting a neighboring pixel pattern in a table in advance and searching therefrom, generating a key code from the neighboring pixel pattern, and referring to the table. Information on whether the target dot is to be turned ON or OFF is given to this neighboring pixel pattern. Therefore, it is determined whether or not the target dot is to be turned on (S13). If it is determined that the target dot is to be turned on, it is further determined whether or not the target dot is a dot OFF (S14).
N (S15). If the dot is a dot ON, nothing is performed. If it is determined in step S13 that the target dot is to be turned off, it is determined whether the target dot is a dot ON (S16).
F (S17). For a dot OFF dot,
Do nothing. This series of processing is performed on all the overlapping pixels, and the overlapping portion W is generated using the generated mask pattern.
Is performed (S18).

The print band joining portion W described so far.
The method of generating an asymmetric mask pattern described above is a method of generating the asymmetric mask pattern in the processing flow. However, if the mask pattern is a certain mask pattern determined by the print head 8, carriage, paper feed accuracy, etc., a table is stored in the memory 7 in advance. It is also possible to store it as a reference and refer to it. Further, depending on the characteristics of the print head 8, the operation may be performed on both overlapping portions W of the two main scans to be joined, or may be performed on only one of them. By applying the method to only one of the overlapping portions W or storing an asymmetric mask pattern in a table, it is possible to increase the speed and reduce the memory.

As described above, according to the present embodiment, the control unit 4 controls the print control circuit 5 so that the mask pattern of the overlapping image is asymmetrical at the overlapping portion between the main scanning and the next main scanning.
And the motor drive circuit 3 are controlled so that even if a shift occurs in the overlapping portion W between the main scanning band 20 and the next main scanning band 30, the shift is not noticeable due to the asymmetry of the mask pattern. , So that the joining portion W of the print band overlaps in the sub-scanning direction,
Not only the separation but also the displacement of the joining portion W of the print band in the main scanning direction can be made inconspicuous. Further, the control unit 4 makes the mask pattern asymmetrical according to the density of the overlapping portion of the image. To prevent white spots from occurring, and to increase the number of dot OFF (no dot) locations in low-density areas so that dots do not overlap or thicken, so that the image quality of the print band junction is not impaired. Can be Further, the control unit 4 makes the mask pattern asymmetrical by the dot pattern of the overlapping portion of the image, so that the dot ON in the portion where the dot density of the overlapping portion is high with respect to the shift between the main scanning and the sub-scanning. To avoid white spots, and to increase the number of dot-off locations in areas with low dot density to prevent dot overlap and fattening, so as not to impair the image quality of the joined parts. Can be. The control unit 4 further includes a memory 7 for storing asymmetric mask patterns in a table, and the control unit 4 refers to the table to make the mask patterns asymmetric, so that a plurality of asymmetric mask patterns are prepared in advance. By doing so, it is possible to maintain the image quality at the junction of the print bands at high speed. Furthermore, the control unit 4 uses only one main scan among the overlapping main scans as an asymmetric mask pattern, so that the upper and lower bands 2 can be maintained in order to maintain the image quality of the junction W of the print band.
Since the asymmetrical mask pattern of only one of the bands 0 and 30 is generated, the processing time for generating the mask pattern is reduced, and the amount of memory is reduced by having only the asymmetrical mask pattern of only one of the bands in the table. Can be reduced to の of the case of both bands.

[0037]

As described above, according to the printing apparatus of the first aspect of the present invention, a print head having a plurality of recording elements, a print control circuit for controlling the drive timing of the print head, and a print head , A carriage motor for driving the recording medium in the sub-scanning direction, a motor drive circuit for driving the carriage motor and the paper feed motor, a print control circuit and a motor drive circuit. And a control unit for performing one line of recording by scanning in a main scanning direction by a carriage motor while driving the print head in accordance with print data by a print control circuit, and performing main scanning and subsequent main scanning. A serial method that connects the print areas and prints by relatively scanning the recording medium in the sub-scanning direction so that a part of the image overlaps with the next main scanning that is the main scanning of The control unit controls the print control circuit and the motor drive circuit such that the mask pattern of the overlapping image is asymmetric at the overlapping portion between the main scanning and the next main scanning, thereby controlling the main scanning. Even if a shift occurs in the overlapping portion between the print band and the print band of the next main scan, printing can be performed so that the shift is not conspicuous due to the asymmetry of the mask pattern. An advantageous effect is obtained that the displacement of the joining portion can be made inconspicuous not only for the overlap and separation but also for the displacement of the joining portion of the print band in the main scanning direction.

According to the printing apparatus of the second aspect, in the printing apparatus of the first aspect, the control unit makes the mask pattern asymmetric by the density of the overlapping portion of the image, thereby performing main scanning and sub-scanning. For the deviation, the number of dots ON (with dots) is increased in a high density portion to prevent white spots from occurring, and in a low density portion, a dot O
An advantageous effect is obtained in that the number of FF (no dot) locations is increased to prevent the dots from overlapping or thickening, so that the image quality at the junction of the print bands can be prevented.

According to the printing apparatus of the third aspect, in the printing apparatus of the first aspect, the control unit makes the main scanning and the sub-scanning by making the mask pattern asymmetric by the dot pattern of the overlapping portion of the image. With respect to the scanning deviation, the number of dots ON is increased in a portion where the dot density of the overlapping portion is high so that white spots are not generated. In the portion where the dot density is low, the number of dots OFF is increased and the overlap of dots is reduced. An advantageous effect is obtained in that the fattening does not occur and the image quality of the joined portion can be prevented from being impaired.

According to the printing apparatus of the fourth aspect, in the printing apparatus of the first aspect, there is provided a memory for storing an asymmetric mask pattern in a table, and the control unit refers to the table to store the mask pattern. By providing the asymmetrical mask pattern, a plurality of asymmetrical mask patterns are prepared in advance, whereby an advantageous effect that the image quality of the joint portion of the print band can be maintained at high speed can be obtained.

According to the printing apparatus of the fifth aspect, in the printing apparatus of the first aspect, the control unit sets only one of the overlapping main scans as an asymmetric mask pattern, Since an asymmetric mask pattern is generated for only one of the upper and lower print bands in order to maintain the image quality at the junction of the print bands, the processing time for generating the mask pattern can be reduced, and Providing the table with only the asymmetric mask pattern of only the band has an advantageous effect that the memory amount can be reduced to １ ／ of that in both cases.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a printing apparatus according to a first embodiment of the present invention.

FIG. 2A is a printing state diagram showing an upper printing band and a lower printing band. FIG. 2B is a printing state diagram showing a case where the printing band overlaps with the bonding portion of the printing band and no separation occurs. (D) A print state diagram showing the case where the print band is overlapped. (E) A print state diagram showing the case where the print band is overlapped. Print state diagram showing

FIG. 3 is a flowchart illustrating a density-based asymmetric mask pattern generation process according to the first embodiment of the present invention;

FIG. 4 is a flowchart showing an asymmetric mask pattern generation process using a pattern according to the first embodiment of the present invention;

5A is a configuration diagram showing a general serial printer. FIG. 5B is a plan view showing a print head of the serial printer shown in FIG.

FIG. 6A is a printing state diagram showing a case in which the printing band overlaps in the sub-scanning direction and does not separate from each other in the sub-scanning direction. FIG. 6B is a printing state diagram showing a case in which the printing band bonding portion overlaps. ) A printing state diagram showing a case where a separation occurs in a joining portion of a printing band. (D) A printing state diagram showing a case where an overlapping portion of a printing band and a shift in a main scanning direction occur. (E) A joining portion of a printing band. State diagram showing the case where there is a gap in the main scanning direction

FIG. 7A is a printing state diagram showing an upper printing band and a lower printing band. FIG. 7B is a printing state diagram showing a case where the printing band overlaps the bonding portion of the printing band and no separation occurs. (D) A print state diagram showing the case where the print band is overlapped. (E) A print state diagram showing the case where the print band is overlapped. Print state diagram showing

[Explanation of symbols]

 Reference Signs List 1 carriage motor 2 paper feed motor 3 motor drive circuit 4 control unit (CPU) 5 print control circuit 6 mask circuit 7 memory 8 print head 11 print head 12 carriage 13 guide 14 platen 15 recording paper (recording medium) 16 printing area (printing) band)

Claims (5)

[Claims] A print head having a plurality of recording elements; a print control circuit for controlling a drive timing of the print head; a carriage motor for driving the print head in a main scanning direction; A paper feed motor for driving; a motor drive circuit for driving the carriage motor and the paper feed motor; and a control unit for controlling the print control circuit and the motor drive circuit. By scanning in the main scanning direction by the carriage motor while driving according to the print data by the control circuit, one line of recording is performed, and the main scanning and the next main scanning which is the next main scanning after the main scanning are performed. A serial printing apparatus that performs printing by connecting printing areas by relatively scanning the printing medium in the sub-scanning direction so that a part of an image overlaps. Wherein the control unit controls the print control circuit and the motor drive circuit such that a mask pattern of the overlapping image is asymmetric at an overlapping portion between the main scanning and the next main scanning. Printing device. 2. The printing apparatus according to claim 1, wherein the control unit makes the mask pattern asymmetrical according to the density of the overlapping portion of the image. 3. The printing apparatus according to claim 1, wherein the control unit makes the mask pattern asymmetrical by a dot pattern of an overlapping portion of an image. 4. The printing apparatus according to claim 1, further comprising a memory for storing an asymmetric mask pattern in a table, wherein the control unit makes the mask pattern asymmetric by referring to the table. 5. The printing apparatus according to claim 1, wherein the control unit sets only one of the overlapping main scans as an asymmetric mask pattern.