JP2000177115A - Printing method and print head for use therein - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printing method for suppressing fluctuation of recording in ink jet printing by reducing the banding and a print head for use therein. SOLUTION: An ink jet head 10 is a line type head having channels 10a corresponding, in number, to the pixels within the width of a sheet 50. An ink drop being ejected from the ink jet head 10 is previously charged positively or negatively. Electrodes 3ia, 3ib (i=1-N) are arranged in the ink jet head 10 while holding at least one channel 10a between. A control section 20 applies a predetermined AC voltage between the electrodes 3ia, 3ib. The control section 20 controls the AC voltage in synchronism with the printing period and the pixel interval of the sheet such that respective pixels in same row in the main scanning direction on the sheet are printed with ink drops ejected from a plurality of channels 10a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing method and a print head apparatus using the method, and more particularly, to a printing method and a printing method for reducing banding caused by printing using an ink jet system and reducing recording unevenness. The present invention relates to an ink-jet type print head device used in the present invention.

[0002]

2. Description of the Related Art At present, an ink jet system is one of the printing systems used in a printer for printing characters and images on a recording member such as printing paper (hereinafter referred to as paper). The ink jet system is a system in which ink droplets are ejected from a print head device and adhere to paper.

There are mainly two types of print head devices used in the above-mentioned ink jet system, a scan type ink jet head device and a line type ink jet head device.

As shown in FIG. 8A, a scan type ink jet head device 101 is a print head device having a size smaller than the width of a sheet of paper 50 to be used. Channel)
Has a number that is greater than or equal to two and less than or equal to the size of the printhead device. Therefore, at the time of printing, it is necessary to scan the scan type inkjet head device 101 perpendicularly to the paper feeding direction.

On the other hand, as shown in FIG.
The line type inkjet head device 102 is a print head device having a size equal to or larger than the width of the paper 50 to be used.
The number of pixels corresponds to the width of the pixel. Therefore, when printing, the line type inkjet head device 10
2 does not need to be scanned perpendicular to the paper feed direction, and printing can be performed in a fixed manner.

[0006]

As described above, in the ink jet system, ink droplets are ejected from a print head device and adhere to paper. Therefore, as shown in FIG. 9A, there is no problem if the size and the ejection direction of the ink droplet ejected from the channel 100a are constant, but the accuracy and the deterioration over time of the print head device 100 alone (for example,
If the size and ejection direction of ink droplets vary due to (clogging of the channel 100a) or the like, banding occurs, as shown in FIG. That is, in FIG. 9B, a streak (a white line that is the color of the paper 50) occurs between the fourth channel and the fifth channel.

In order to reduce the banding, conventionally, an orifice having a more uniform channel is selected or the orifice is frequently cleaned. However, when the former is performed, the yield becomes worse as the number of channels increases, and when the latter is performed, there is a problem that the recording speed decreases.

Accordingly, in a scan type ink jet head device, as shown in FIG. 10, printing is performed by performing interlacing instead of printing in accordance with the arrangement of channels. (Without taking into account the variation of the ink droplets), the ink droplets are individually controlled and printed in a uniform size.

In FIG. 9 and FIG. 10, a print head device 100 having eight channels 100a is provided.
FIG. 5 is a diagram illustrating an example of the state of ink adhesion on the surface of the paper 50 when ink droplets are ejected onto the paper 50. Also, in FIG. 10, which channel 1
00a indicates which ink is attached by the same number.

For example, referring to FIG. 10, a scan type ink jet head apparatus for performing the above-described interlacing will be described first with respect to a first line, in sixth and eighth channels, then in first, third, fifth and fifth channels. Ink droplets are ejected in the order of the seventh channel, and finally the second and fourth channels. With respect to the second line, ink droplets are ejected in the order of the fifth and seventh channels, then the second, fourth, sixth and eighth channels, and finally the first and third channels. Thereafter, this operation is repeated.

However, in the line type ink jet head device 102, since the print head device is fixed, it is not possible to perform interlaced printing as in the scan type ink jet head device 101 described above.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a printing method for reducing banding and reducing recording unevenness in printing using an ink jet system, and a print head device used in this method.

[0013]

Means for Solving the Problems and Effects of the Invention A first invention is a method for printing using a line type print head device by an ink jet system, wherein the print head device is a paper sheet to be printed. It has channels (holes for ejecting ink droplets) of the number of pixels corresponding to the print width in the direction perpendicular to the feed direction. The method is characterized in that a recording line, which is controlled by bending a trajectory and records a plurality of pixels in a line in a paper feed direction on a sheet, is printed using ink droplets ejected from two or more different channels.

According to a second aspect of the present invention, there is provided a method of printing using a scan type print head device by an ink jet system, wherein the print head device prints two or more channels (holes for ejecting ink droplets) on a print target. It has the same direction as the paper feed direction of a certain paper, and controls the attachment position of the ink droplet ejected from the channel on the paper by bending the flight trajectory of the ink droplet. In this method, a recording line for recording a plurality of pixels in a line is printed using ink droplets ejected from two or more adjacent channels.

As described above, according to the first and second aspects of the present invention, the positions of the ink droplets ejected from the channels on the paper are controlled, and each pixel to be printed in a line is ejected from the plurality of channels. Printing using alternating ink droplets. As a result, ink droplets ejected from the same channel are not printed linearly in the paper feeding direction (main scanning direction) of the paper, so that banding can be reduced and recording unevenness can be reduced.

A third invention is an invention according to the first and second inventions, wherein one or two or more channels are predetermined with one or more channels interposed therebetween. It is characterized in that the flight trajectory of the ink droplet is bent by generating an electric field.

As described above, according to the third aspect, the first aspect
In the second invention, a predetermined electric field is generated across the channel. This makes it possible to easily bend the flight trajectory of the ink droplet.

A fourth invention is an invention according to the third invention, wherein the electric field is intermittently made unidirectional or bidirectional in synchronization with the timing at which ink droplets are ejected from the channel. The ink droplets are generated and alternately bent by an integral multiple of the print dot width on the paper.

As described above, according to the fourth aspect, the third aspect
Specifies a method of generating an electric field when controlling the flight trajectory of an ink droplet using the electric field in the invention of the above. As a result, ink droplets ejected from the same channel are not printed linearly in the main scanning direction, so that banding can be reduced and recording unevenness can be reduced.

A fifth aspect of the present invention is a line type print head device using an ink jet system, wherein a channel (ink droplet) having a number of pixels corresponding to a print width is provided in a direction perpendicular to a paper feeding direction of a sheet to be printed. A line type inkjet head having a hole for ejecting ink droplets, and control means for controlling the position of ink droplets ejected from the channel on the paper by bending the flight trajectory of the ink droplets. It is characterized in that a recording line for recording a plurality of pixels in a line in a paper feeding direction on a sheet is printed using ink droplets ejected from two or more different channels.

As described above, according to the fifth aspect of the present invention, the positions of the ink droplets ejected from the channels on the paper are controlled, and the pixels printed in a line are alternately ejected from the plurality of channels. Print using. This allows
Ink droplets ejected from the same channel are not printed linearly in the main scanning direction, so that banding can be reduced and recording unevenness can be reduced.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIG. 1 is a view showing the main components of a line type ink jet head device used in a printing method according to a first embodiment of the present invention. FIG. 1A is a front view of the ink jet head device, and FIG. 1B is a cross-sectional view taken along line AA in FIG. 1A. In FIG. 1, an inkjet head device includes an inkjet head 10;
Control unit 20, electrodes 31a, 31b to 3Na, 3Nb
(N is a positive integer).

First, referring to FIG.
The configuration of the head device will be described. The ink-jet head 10 is a print head device having a size equal to or larger than the width of the paper 50 to be used, and has channels 10a as many as the pixels of the width of the paper 50. The inkjet head 10 may be any suitable print head as is well known in the art, such as a method of ejecting ink droplets by bubbles or a method of ejecting ink droplets by vibration of a piezoelectric element such as a piezo element. It is. The ink droplet ejected by the inkjet head 10 is positive (plus) in advance.
Or it is charged to a negative (negative) charge. Electrode 31
a, 31b to 3Na, 3Nb are electrodes 3ia, 3ib
(I = 1 to N) are paired, and are arranged on the inkjet head 10 so that at least one channel 10a is interposed between the electrodes 3ia and 3ib. The control unit 20 applies a predetermined AC voltage between the pair of electrodes 3ia and 3ib, and generates an electric field between both electrodes. As will be described later, at this time, the control unit 20 controls the electrode 3ia and the electrode 3ib in synchronization with the printing cycle on the paper 50.
A predetermined AC voltage is applied so that the electric field generated between the two varies. In addition, the electrode 31 performed by the control unit 20
The control of a, 31b to 3Na, and 3Nb can be performed digitally in addition to the analog control using the AC voltage as described above.

Next, a printing method according to the present embodiment, which is performed using the ink jet head device having the above configuration, will be described with reference to FIGS. FIG. 2 shows the electrode 3i
a, 3 ib and the channel 10
FIG. 3 is a diagram illustrating a relationship between an ink droplet ejected from FIG. In the following description, it is assumed that the ink droplet has been charged to a positive charge in advance. FIG. 3 is a diagram showing the operation timing of printing in the printing method according to the first embodiment of the present invention. In FIG. 3, the inkjet head 10 that performs printing has first to n-th channels 10a. It is also assumed that the recordable range of the sheet 50 is the third to n-th columns. FIG. 4 is a diagram illustrating an example of how ink adheres to the surface of the sheet 50 by the printing method according to the first embodiment of the present invention.

As described above, the control unit 20 applies an AC voltage between the pair of electrodes 3ia and 3ib. By controlling the voltage value and timing of the applied AC voltage, the ink droplets on the paper 50 are controlled. Control the print position of. This control will be described separately for a sub-scanning direction, which is a direction perpendicular to the paper feeding direction of the paper 50, and a main scanning direction, which is a paper feeding direction for the paper 50.

The control in the sub-scanning direction is performed as follows according to the voltage value of the AC voltage of the control unit 20. Control unit 20
AC voltage applied between the electrodes 3ia and 3ib from the
In the case of [V] (that is, when no electric field is generated between the two electrodes), since the ink droplet charged to the positive charge has no effect, the ink droplet ejected from the channel 10a It flies straight and adheres to the paper 50 (FIG. 2A). On the other hand, electrodes 3ia and 3ib
When the AC voltage applied between the electrodes is + E [V] (that is, when an electric field is generated in the direction from the electrode 3ia to the electrode 3ib), the ink droplets are drawn to the electrode 3ib side, so that the channel The ink droplet ejected from 10a changes its flight trajectory and adheres to the paper 50 (FIG. 2).
(B)). In this case, the control unit 20 determines that the point at which the ink droplet changes its flight trajectory and adheres to the paper 50 is the position of the pixel to be printed when the channel 10a adjacent to the electrode 3ib directly splatters the ink droplet. As described above, the AC voltage + E [V] is set. The control unit 20
The AC voltage applied between the electrodes 3ia and 3ib is -E
[V] (that is, from the electrode 3ib to the electrode 3i
In the case where an electric field is generated in the direction a), the ink droplet is drawn to the electrode 3ia side, so that the ink droplet ejected from the channel 10a changes its flight trajectory and adheres to the paper 20 (FIG. 2). (C)). In this case,
The control unit 20 controls the AC so that the point at which the ink droplet changes its flight trajectory and adheres to the paper 50 is the position of a pixel to be printed when the channel 10a adjacent to the electrode 3ia side directly blows the ink droplet. Voltage -E [V] is set.

On the other hand, the control in the main scanning direction is performed in the following manner according to the timing at which the control unit 20 applies the AC voltage. The control unit 20 sets the timing for setting the AC voltage to 0 [V], the timing for setting + E [V], and the timing -E
The timing of [V] is controlled in synchronization with the printing cycle on the paper 50.

The control section 20 controls both the sub-scanning direction and the main scanning direction at the operation timing shown in FIG. In FIG. 3, C1 to Cn indicate the first to nth channels 10a for ejecting ink droplets at the corresponding positions. Referring to FIG. 3, in the first row, since the AC voltage is 0 [V], the second to (n−1) th channels 10 a are ink drops ejected straight, and the third to n-th columns are ink drops. Are printed respectively. Next, in the second row, since the AC voltage is + E [V], the first to (n-2) th channels 10a are ink droplets whose flight trajectories are changed by the electric field and ejected, and Each of the n columns is printed.
Next, in the third row, as in the first row, the AC voltage is 0 [V].
Therefore, the third to n-th columns are printed with the ink droplets ejected straight from the second to (n-1) -th channels 10a, respectively. Next, in the fourth row, the AC voltage is -E
[V], the third to n-th columns are printed with ink droplets ejected by changing the flight trajectory of the third to n-th channels 10a by the electric field. Next, in the fifth row, since the AC voltage is 0 [V] as in the first and third rows, the second to (n-1) th channels 10a are ink droplets that are ejected straight, The third to n-th columns are printed, respectively. Hereinafter, this line printing is repeatedly performed, and banding is reduced as shown in FIG.

As described above, according to the printing method and apparatus according to the first embodiment of the present invention, the position at which ink droplets ejected from the channel 10a are adhered on the paper 50 is controlled.
Each pixel in the same row is printed using ink droplets ejected from the plurality of channels 10a alternately. As a result, ink droplets ejected from the same channel 10a are not printed linearly in the main scanning direction, so that banding can be reduced and recording unevenness can be reduced.

In the first embodiment, a case where a line type print head device is used as the ink jet head device has been described. However, a scan type ink jet head device can be similarly used. It is.

In the first embodiment, the position of the ink droplet adhering to the sheet 50 due to the change of the flight trajectory due to the AC voltage ± E [V] applied between the electrodes 3ia and 3ib is set to the adjacent channel. Although the position of the pixel to be printed when the ink droplet is skipped straight at 10a, that is, the flight trajectory change of one pixel has been described, the flight of two pixels or more can be performed by arbitrarily setting the voltage value of the AC voltage. It is also possible to change the orbit.

Further, in the first embodiment, the case where an electric field is generated by applying a voltage between the electrodes using the electrodes 31a and 31b to 3Na and 3Nb has been described. Even if a magnetic field is generated between the magnetic poles, the above-described printing method of the present invention can be similarly realized. However, in this case, it is necessary to previously magnetize either the S pole side or the N pole side using the magnetic toner ink.

Further, in the first embodiment,
Multiple channels 1 as inkjet head device
Inkjet head 1 provided with 0a in a line
Although described using 0, it is also possible to use an ink jet head in which a plurality of channels 10a are provided in a staggered arrangement as shown in FIG.

(Second Embodiment) As a measure against banding at the time of printing, the first embodiment uses a single inkjet head device and changes the flight trajectory of ink droplets ejected from the channel 10a. went. On the other hand, the printing method according to the second embodiment of the present invention uses a plurality of ink-jet head devices, and does not change the flight trajectory of the ink droplet ejected from the channel 10a. We are going to take measures. Hereinafter, a printing method according to the second embodiment of the present invention will be described.

FIG. 6 is a perspective view showing main components of a line type ink jet head device used in a printing method according to a second embodiment of the present invention. In FIG. 6, the inkjet head device includes two inkjet heads 11 and 12 and a control unit 21. FIG. 7 shows how to use the inkjet heads 11 and 12 and the paper 5 according to the printing method according to the second embodiment of the present invention.
FIG. 6 is a diagram illustrating an example of the state of ink adhesion on a zero plane.

Each of the ink jet heads 11 and 12 is a print head device having a size equal to or larger than the width of the paper 50 used together, and has channels of the number of pixels corresponding to the width of the paper 50. This inkjet
The heads 11 and 12 are any suitable print heads that are well known in the art, such as a method of ejecting ink droplets by bubbles or a method of ejecting ink droplets by vibration of a piezoelectric element such as a piezo element. is there. The control unit 21 controls the inkjet head 11 and the inkjet head 12 to be used alternately for printing in synchronization with a printing cycle on the paper 50. That is, referring to FIG.
Prints the first row using the inkjet head 11 and the second row using the inkjet head 12. Hereinafter, the odd-numbered rows are similarly assigned to the inkjet head 1.
1 and the even rows are repeatedly printed using the inkjet head 12.

As described above, according to the printing method and apparatus according to the second embodiment of the present invention, printing is performed by changing the ink jet head used for each row. As a result, ink droplets ejected from the same ink jet head, that is, the same channel, are not printed linearly in the main scanning direction, so that banding can be reduced and recording unevenness can be reduced.

In the second embodiment, the case where two ink jet heads 11 and 12 are used as the ink jet head device has been described. However, it is of course possible to use three or more ink jet heads. It is.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating main components of a line type inkjet head device used in a printing method according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a relationship between an AC voltage applied between electrodes 3ia and 3ib and a flight trajectory of an ink droplet ejected from a channel 10a.

FIG. 3 is a diagram illustrating a printing operation timing in the printing method according to the first embodiment of the present invention.

FIG. 4 is a diagram illustrating an example of how ink adheres to the surface of a sheet of paper by a printing method according to the first embodiment of the present invention.

FIG. 5 is a diagram illustrating an example of another inkjet head that can be used in the printing method according to the first embodiment of the present invention.

FIG. 6 is a perspective view showing main components of a line type inkjet head device used for a printing method according to a second embodiment of the present invention.

FIG. 7 is a diagram illustrating an example of how to use the ink jet heads 11 and 12 and how ink adheres to the surface of a sheet 50 by a printing method according to a second embodiment of the present invention.

FIG. 8 shows a scan type inkjet head 10.
FIG. 3 is a diagram for explaining a difference between No. 1 and a line type inkjet head 102.

FIG. 9 is a diagram illustrating an example of a difference in the degree of ink adhesion on the surface of a sheet of paper 50 when banding occurs and when banding does not occur.

FIG. 10 shows a sheet 5 when banding is performed in a conventional scan type inkjet head.
FIG. 6 is a diagram illustrating an example of the degree of ink adhesion on surface 0.

[Explanation of symbols]

 10-12 Inkjet heads 10a, 100a Channels (injection holes) 20, 21 Control unit 50 Paper 31a-3Na, 31b-3Nb Electrodes 100 Printhead device 101 Scan type inkjet head device 102 Line type inkjet head device

Claims (5)

[Claims] 1. A method for printing using a line type print head device by an ink jet method, wherein the print head device corresponds to a print width in a direction perpendicular to a paper feeding direction of a sheet to be printed. It has channels (holes for ejecting ink droplets) of the number of pixels, and controls the attachment position of the ink droplets ejected from the channel on the paper by bending the flight trajectory of the ink droplets. A printing method, wherein a printing line for printing a plurality of pixels in a line in the paper feed direction is printed using ink droplets ejected from two or more different channels. 2. A method for printing using a scan type print head device by an ink jet system, wherein the print head device forms two or more channels (holes for ejecting ink droplets) on paper to be printed. It has the same direction as the paper feed direction, and controls the attachment position of the ink droplet ejected from the channel on the paper by bending the flight trajectory of the ink droplet, and is perpendicular to the paper feed direction on the paper. A printing method, wherein a printing line for printing a plurality of pixels in a row in one direction is printed using ink droplets ejected from two or more adjacent channels. 3. A flight trajectory of an ink droplet is generated by generating a predetermined electric field across one or more channels for each of one or more channels. The printing method according to claim 1, wherein the printing method is performed. 4. The method according to claim 1, wherein the electric field is generated intermittently in one direction or in two directions in synchronization with the timing at which the ink droplets are ejected from the channel, so that the ink droplets have a width of a print dot on the paper. The printing method according to claim 3, wherein the printing method is alternately bent by an integral multiple. 5. A line type print head device using an ink jet system, comprising:
Line-type inkjet printer with channels (holes for ejecting ink droplets) with the number of pixels corresponding to the print width
A head, and control means for controlling an attachment position of the ink droplet ejected from the channel on the paper by bending a flight trajectory of the ink droplet, and a line of a plurality of pixels in the paper feeding direction on the paper. A print line for printing on a recording line using two or more different ink droplets ejected by said channels.