JPH0262243A - Printing method - Google Patents

Abstract

PURPOSE:To improve the quality of printing by conducting printing so that mutually adjacent positions in a first direction of a plurality of dot groups printed by a recording head are set randomly in a second direction. CONSTITUTION:A region 2A printed by a first recording head and a region 2B printed by a second recording head are overlapped. The boundaries (positions where dots 1a and dots 1b are adjoined in the X direction) of dot groups 1A formed by arranging a plurality of the dots 1a in the X direction and dot groups 1B shaped by disposing a plurality of the dots 1b in the X direction are distributed randomly in the Y direction. Accordingly, the boundaries of overlapped regions 2 and regions except the regions 2 are not shaped to a straight line and are formed randomly, thus preventing the appearance of band-shaped black stripes and white stripes, etc. in the regions 2, then improving the quality of printing.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention uses a recording head whose printing unit is a group of dots in which a plurality of dots are arranged in a first direction, and prints the group of dots on a recording medium. Regarding a printing method in which printing is performed by placing the image on the body in the first direction and in a second direction orthogonal to the first direction, it is possible to improve the printing quality of a dot matrix printer in particular. Concerning printing methods.

(Prior art and its problems) Conventionally, this type of printer has been designed to print a plurality of dots (hereinafter referred to as the "sub-scanning direction") in the feeding direction of paper, which is the recording medium.
For example, a recording head for printing n dots) is provided, and this recording head is scanned by a predetermined number of dots (for example, m dots) in a direction perpendicular to the sub-scanning direction (hereinafter referred to as the "main scanning direction") to print an nxm dot matrix. The first line is printed, then the paper is sent in the sub-scanning direction, the recording head is scanned in the main scanning direction, and the second line is printed using the same dot matrix of <nxm, and so on. There is a system in which printing is performed sequentially from the third line onwards.

However, in this printer, it is difficult to adjust the seams between adjacent lines.

In other words, if the bottom dot of one printed line and the top dot of the next line are overlapped too much, the density of that part becomes high and dark streaks appear at the seam. On the other hand, if the distance between the dots is too large, white sushi will appear at the seam. Therefore, by improving the mechanical precision of the printer,
It is desirable to control the voltage applied to the printer and adjust the dot spacing between the two to an appropriate value so that the seam is not noticeable. However, the dot spacing is determined not only by controllable factors such as mechanical precision, but also by factors that are generally difficult to control, making it difficult to adequately adjust the dot spacing. Here, examples of factors that are difficult to control include expansion and contraction of paper, which is the recording medium. In other words, the expansion and contraction of paper changes with the environment in which the printer is used (temperature, humidity, etc.), and since temperature etc. change from moment to moment, it simply depends on the mechanical accuracy etc. If only the temperature is controlled, the paper expands and contracts with changes in temperature and the like, causing subtle changes in the dot spacing, resulting in a problem in that sufficient printing quality cannot be achieved.

Therefore, techniques for solving this problem have been proposed in the past. For example, according to Japanese Patent Application Laid-Open No. 55-42836, as shown in FIG.
A and the printing area 10B in the next row, B, are overlapped by at least one dot, and in the overlapped joint part 10, the printing of the dots arranged in the odd numbered columns is performed when printing in the A row. On the other hand, dots arranged in even-numbered columns are printed at the time of printing the B row. In the figure, dots (white circles) are shown when printing rows '1QaG and tA, and 10b represents dots (shaded circles) when printing rows B.

In addition, according to Un FfLa 60 107975, as shown in FIG.
A plurality of dots are overlapped in the printing area 11B in the next row B, and in the overlapped joint part 11, the dots arranged in the odd numbered row are printed while printing the A row. , dots arranged in even-numbered rows are printed when printing the B row. In addition, in the same figure, lla
11b represents a dot (white circle) when printing row A, and 11b represents a dot (shaded circle) when printing row B.

However, in such a conventional printing method, although the printing quality can be improved compared to the previous printing method without the joint part 10. Because the dots are arranged in a regular manner, black or white streaks may appear at the border of the seam, or band-like black or white streaks may appear within the seam, making it difficult to expect sufficient printing quality. The problem was that there was no.

(Object of the Invention) The present invention has been made in order to solve the above problems, and an object thereof is to provide a printing method that can improve the printing quality of a dot matrix printer.

(Means for Achieving the Object) The present invention uses a recording head whose printing unit is a group of dots in which a plurality of dots are arranged in a first direction, and prints the group of dots onto a recording medium in the first direction. 1 direction and a second direction perpendicular to the first direction, the printing method comprises: printing the plurality of dots in the first direction; It is characterized in that printing is performed such that the positions where the groups are adjacent to each other are random in the second direction.

(Example) A0 Summary of the Invention Fig. 1 is an explanatory diagram for explaining the outline of the printing method according to the invention, in which a dot consisting of a predetermined number of dots arranged in the X direction (for example, the main scanning direction) is used. A plurality of recording heads (not shown) that print in groups as printing units are arranged along the X direction, and the recording medium is moved along the Y direction perpendicular to the X direction.
FIG. 2 is a diagram schematically showing a part of the printing surface formed on a recording medium when the present invention is applied to a dot printer that performs predetermined printing by feeding dots in the direction of 1 dot]. In the figure, dot 1a (white circle) is printed by one of the plurality of recording heads (hereinafter referred to as "first recording head"), and dot 1b (hatched circle) is the one printed by the above-mentioned one. The image is printed by a recording head located adjacent to the first recording head (hereinafter referred to as "second recording head").

As shown in the figure, an area 2A printed by the first recording head and an area 2B printed by the second recording head overlap, and a plurality of dots 1a
A dot group 1A formed by arranging dots in the X direction, and a dot group 1 formed by arranging a plurality of dots 1b in the X direction.
B (locations where dots 1a and 1b are adjacent in the X direction) are randomly arranged in the Y direction. Therefore, the boundary between the overlapping region 2 and other regions is not linear as in the conventional example,
Since it is random, band-like black streaks, white streaks, etc. do not appear in area 2, and the printing quality in area 2 is further improved.

Below, printers to which the above invention is applicable will be shown, and embodiments thereof will be described in detail.

B. First Embodiment First, an example of a printer to which the present invention can be applied is a charge deflection type inkjet printer.

This charge deflection type inkjet printer constantly supplies ink to the nozzle portion of the recording head, vibrates a piezoelectric element attached to the nozzle at a constant frequency, and ejects the ink from the nozzle at regular intervals to form particles.
band? An image is printed on a recording medium by photographing the flight direction of ink particles vertically or horizontally using a faff pole and a deflection electrode. Here, we will discuss a system in which a plurality of nozzles that print several dots in the main scanning direction are arranged in a straight line along the main scanning direction, and the recording medium is sent one bit at a time in the sub-scanning direction to make a predetermined impression. explain.

FIG. 2 is a block diagram showing the basic configuration of a charge deflection type inkjet printer to which an embodiment of the printing method according to the present invention can be applied. As shown in FIG. 2, binarized image data 21a, 21b, . . . are stored in the image memory 21.
In response to an instruction from a controller (not shown), each line is transferred to a one-line buffer 23 provided in the shift device 22 in accordance with the printing order as printing data indicating whether or not printing is necessary. The shift device 22 is connected to the random number generator 24 and shifts the print data transferred to the one-line buffer 23 to the left by the number of bits corresponding to the random number n given from the random number generator 24. And random number n
The printing f-1 shifted to the left by the amount of the printing device 2
The printing data is divided into five parts, and the divided printing data is transferred to each printing unit 26. In this way, each image data 2
1a.

21b..., the area to be printed by each printing unit 26 is adjusted based on the random number n.

Each printing unit 26 includes a driving device 30 including a printing data control section 27, a printing position control section 28, and a driving circuit 29, and a printing bag M25. Predetermined printing is performed based on the random number n given to the control section 2B and the printing data given from the shift device 23 to the printing data control section 27.

FIG. 3 is a detailed block diagram of the printing unit 26 shown in FIG. 2. The printing data control unit 27 is equipped with a printing memory 31, and when the divided printing data is transferred from the 1-line buffer 23 to the printing memory 31, the printing data is transferred to the printing memory 31 according to the printing clock C according to instructions from the controller. 31
The printing data within is sequentially output one bit at a time to the input side of a gate 34, which will be described later.

Further, the printing position control 'F1iS 28 is composed of an up counter 32, an adder 33, and a gate 34, and the up counter 32 is controlled by an instruction from the controller.
is preset and then incremented based on the printing clock C, and the output value of the up counter 32 and the random number n are added by the adder 33, and printing position data taking into account the shift by the random number n is sequentially obtained. create. This printing position data is given to the other input side of the gate 34.
Then, based on the printing data sequentially given from the printing memory 31, the passage of the printing position data is controlled.

That is, when the print data given from the print memory 31 is, for example, ``''O++'' representing content that does not need to be printed, the passage of the print position data is restricted, while the print data is the content that does not require printing. When the value is 1'' representing , printing position data is allowed to pass. In this way, the printing position data that has passed through the gate 34 is given to the drive circuit 29.

The drive circuit 29 is composed of a D/A converter 35 and an amplifier 36, and the printing position data output from the gate 34 is D/A converted by the D/A converter 35, and further amplified by the amplifier 36. and provides it to the printing device 25. The printing device 25 is configured to print only at a position corresponding to the above-mentioned printing position data using a nozzle portion which is a recording head, and thus print corresponding to the image data.

Next, a specific printing procedure when printing using the inkjet printer configured as described above will be described with reference to FIG. 4. First, image data 218, 211), etc. are stored in the image memory 21 (step 81).
). Here, for the following explanation, the image data 21a is 28-bit binary data d, d, ..., d.
28.

Next, one line of image data 21 is stored in the image memory 21.
a(d , d , ·”, 62g) to the 1-line buffer 23 (step 82).Then, the random number generator 24 generates a random number n (step S3).Here, for the following explanation, , the random number n is IQIZI“1゛′
, "2", and the one-line buffer 23 is composed of 30 bits.

Next, in step S2, the image data 21a (d
, d, =-, d28) is shifted to the left by the value of the random number n (step 84). For example, when the value of the random number n is 1'', the memory contents of the 1-line buffer 23 are 'O, d, d, . . . , d28,''.

Then, this memory content is divided into the number of printing units 26 (step S5).

Here, for the following explanation, the number of printing units 26 is set to 5.
'', and assume that the above memory contents are divided into 5 equal parts of 6 bits each. Therefore, for example, if the contents are as shown above,
If "O, d, d, ..., d28°0'', the printing data transferred to each printing unit 26a to 268 will be "O, dl, ... d5, pad d6,
°゛°・dll・”dl2・°°゛・d17it
d ..., d'' and "d , ..., d28
゜18・23 2401
It becomes 1.

Next, by performing steps 86 to S10 in the first to fifth printing units 26a to 26e,
1 corresponding to the image data 21a on the recording medium based on the printing data transferred to each printing unit 26a to 26e.
The printing of the lines is executed. That is, after the up counter 32 is preset in response to a printing start command (not shown) given to each of the printing units 26a to 26e from a controller (not shown), the up counter 32 performs an up counting operation based on the printing clock C. (Step S6). Then, the up count value and the value of the random number n are added by the sifter 33 (step S7), and the printing position data, which is the added value, is applied to one input side of the gate 34, while the printing clock One dot worth of printing data stored in the printing memory 31 is read out in accordance with C (step S8) and applied to the other input side of the gate 34. gate 3
4 controls the passage of the printing position data output from the adder 33 based on the printing data, and controls the passage of the printing position data output from the adder 33.
The printing operation of the printing device 35 is controlled based on the output signal of (step 89). In other words, when the data read from the printing memory 31 is Or+ indicating content that does not require printing, passage of the printing position data 1 to 34 is restricted and no printing is performed; When the content is "1", the printing position data is allowed to pass through the gate 34,
Based on the printing position data, one dot is printed at a position corresponding to the data. Then, in step S10, until it is confirmed that the above processing (steps 87 to 89) has been executed for all of the print data, in other words, the process is performed by the number of bits of the print data (6 times in this case). The operations of the above processing (steps 86 to S9) are repeated.

Since the above operations are performed simultaneously in each of the printing units 26a to 26e, one line of 28 dots corresponding to the image data 21a is printed by the series of operations described above.

Furthermore, in step S11, it is determined whether or not the printing process for all lines has been completed, that is, whether or not there is unprocessed image data. A series of actions (step $2~
Step 510) is repeated to sequentially execute the printing process for each line, and when the printing process for the last line is completed, all the work is completed.

When printing is performed as described above, the image is printed as shown in FIG. 5, for example. FIG. 5 is a diagram schematically showing a part of the printing surface when printing is performed on a recording medium by applying an embodiment of the printing method according to the present invention to the above printer.

However, in this embodiment, the first to fifth printing units 26a to 26e, each having a nozzle portion that prints as a printing unit a group of dots consisting of a predetermined number of dots arranged in the main scanning direction, are used in the main scanning direction. They are arranged in a straight line along the direction, and the recording medium is fed dot by dot in the sub-scanning direction perpendicular to the main-scanning direction to perform predetermined printing. In the figure, a dot 51a (white circle) is printed by the first printing unit 26a, and a dot 51b (white circle) is printed by the first printing unit 26a.
The dots 51c (circles with diagonal lines) and dots 51c (circles with X marks) are the second and fifth printing units l-26b, respectively.
26C! They were each printed by. Furthermore, the value of the random number n when printing the first line is "2", and similarly the value of the random number n when printing the second to fifth lines is "2".
0", "1"""2", "°O".

As shown in the figure, the area 52A printed by the first printing unit 26a and the area 52B printed by the second printing unit 26b overlap and are formed in the main scanning direction. Since the boundaries between the dot group 51A and the dot group 51B are arranged randomly in the sub-scanning direction, the boundaries between the overlapping area 52 and other areas are not linear as in the conventional example, but are random. Therefore, band-like black streaks and white streaks do not appear in the region 52, and the printing quality in the region 52 is further improved. Note that although the above description has been made regarding the joint between the first and second printing units 26a and 26b, the joint between the other printing units is also printed in the same manner as above, and the printing quality of that part is different. Needless to say, it will be improved.

In the embodiment L, the image data 21a, 21b, . . . stored in the image memory 21 is partially shifted by a random number n using the shift device 22, but as shown in FIG. 1 line data 23a partially shifted by random number n in advance by internal rough 1 to wear;
23b, . . . may be prepared and stored in the image memory 21. In this case, the shift device 22 becomes unnecessary, and the configuration of the printer becomes simple. Also,
As described above, since there is no need to generate a random number n at a predetermined timing during printing to shift the image data 21a, 21b, . . . , the printer can be easily controlled.

C0 Second Embodiment In the first embodiment above, the case where an embodiment of the present invention is applied to a charge deflection type inkjet printer has been described, but the scope of application of the present invention is limited to charge deflection type inkjet printers. For example, it is applicable to on-demand inkjet printers.

This on-demand inkjet printer applies a pulse voltage to the piezoelectric element on the back of the ink chamber to increase the pressure in the ink chamber, which causes ink to be ejected from the nozzle, turned into particles, and printed onto the recording medium. This is Surushino.

FIG. 7 is a diagram showing a schematic configuration of an on-demand type inkjet printer to which an embodiment of the present invention can be applied. In the figure, 71a to 71d are first to fourth recording heads each having a plurality of nozzles 72 arranged in the main scanning direction. The end portions 71d are arranged so as to overlap each other in the sub-scanning direction.

FIG. 8 is a diagram schematically showing a part of the printing surface when printing is performed on a recording medium by applying an embodiment of the printing method according to the present invention to the printer shown in FIG. 7. be. In the same figure,
The dot group 81A is printed by the first recording head 71a, and similarly, the dot groups 81B to 81D are printed by the second to fourth recording heads 71b, 71c, and 71, respectively.
These were printed by d. That is,
The printer shown in FIG. 7 has a dot group 81B, 8
1D as the second and fourth recording heads 71b.

71d, the recording medium is sent in the sub-scanning direction, and then the first and third recording heads 71a,
71c to print the m-th row of dots 81A and 81C, and by printing a plurality of rows at the above-mentioned timing, for example, as shown in FIG. 8 is printed.

As shown in the figure, even when the printing method according to the present invention is applied to an on-demand inkjet printer, similarly to the first embodiment, areas printed by mutually adjacent recording heads (for example, , area 82 in the same figure) overlap, and the boundaries between mutually adjacent dot groups (for example, dot group 81A and dot group 81B) are arranged randomly in the sub-scanning direction. It has the same effect as the example.

D. Third Embodiment Although the first and second embodiments described above describe the case where the present invention is applied to a line blink, the scope of application of the present invention is not limited to the above-mentioned line printer. , can also be applied to serial printers.

Here, as a serial printer, for example, a recording head in which a plurality of nozzles are arranged in the main scanning direction is scanned in the main scanning direction by an appropriate drive device to print the -share, and the recording medium is sequentially 01 One example is one that is configured to be sent in the scanning direction and to scan the recording head in the main scanning direction to perform printing.

FIG. 9 is a diagram schematically showing a part of the printing surface when printing is performed on a recording medium by applying an embodiment of the printing method according to the present invention to the serial printer. In the same figure,
Dot groups 91A and 918° 91G are in the 1st and 2nd rows, respectively.
These are the prints of the rows and nth rows.

As shown in the figure, when an embodiment of the printing method according to the present invention is applied to a serial printer, the printing area of a certain line and the printing area of the next line are a partial area ( For example, dot groups (for example, dot group 91A and dot group 91
Since the boundaries in B) are randomly arranged in the main scanning direction, the same effects as in the first and second embodiments are achieved.

E. Other Implementations In the first to third embodiments above, the case where the present invention is applied to an inkjet printer has been described, but the scope of application of the present invention is not limited to inkjet printers, but can be applied to wire dot printers in general. It goes without saying that you can.

(Effects of the Invention) As described above, according to the present invention, the positions of the plurality of dot groups printed by the recording head that are adjacent to each other in the first direction are printed at random in the second direction. This has the effect of improving printing quality.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram for explaining the outline of the printing method according to the present invention, FIG. 2 is a block diagram showing the basic configuration of a charge deflection type inkjet printer to which the present invention can be applied, and FIG. 4 is a detailed block diagram of the printing unit shown in FIG. 2, FIG. 4 is a flowchart showing the printing procedure when printing by the printer shown in FIGS. 2 and 3, and FIG. 5 is a detailed block diagram of the printing unit shown in FIG. 6 is a diagram schematically showing a part of the printing surface when printing is performed on a recording medium by applying an embodiment of the printing method according to the present invention to the above-mentioned printer, and FIG. Figure 1 shows the contents of an image memory of a charged deflection type inkjet printer to which the invention can be applied, Figure 7 shows a schematic configuration of an on-demand type inkjet printer to which the invention can be applied, and Figure 8 7th
9 is a diagram schematically showing a part of the printing surface when printing is performed on a recording medium by applying an embodiment of the printing method according to the present invention to the printer shown in the figure; FIG. 10 is a diagram schematically showing a part of the printing surface when printing is performed on a recording medium by applying an embodiment of the printing method according to the present invention to a serial printer, and FIG.
FIG. 1 is an explanatory diagram for explaining the outline of a conventional printing method.

Claims (1)

[Claims] (1) Using a recording head whose printing unit is a group of dots in which a plurality of dots are arranged in a first direction, the group of dots is printed onto a recording medium in the first direction and in the first direction. A printing method in which dots are printed so as to be arranged in a second orthogonal direction, and the positions where the plurality of dot groups are adjacent to each other in the first direction are random in the second direction. A printing method characterized by: