JP3388094B2 - Ink jet recording method and apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording method and apparatus, and more particularly to an ink jet recording method and apparatus that suppress deterioration in recording image quality due to variations in the flight direction of ink particles.

[0002]

2. Description of the Related Art In an ink jet recording apparatus, a line is recorded by scanning a head in the main scanning direction while the paper is stationary. As a result, one line is recorded with dots (dot lines) corresponding to the number of nozzles included in the head.
After that, the paper is fed in the sub-scanning direction, and the next line is recorded in the same manner. By repeating such operation,
Image information such as characters, symbols and figures is recorded on one page of paper.

[0003]

By the way, the flight direction of the ink particles flying from each nozzle of the head is such that a minute defect occurs in the nozzle portion due to ink adhering to the nozzle portion, variation in manufacturing of the nozzle, or the like. However, even if they are driven with the same drive signal, they are not all the same. In reality, the flight direction of the ink particles has a three-dimensional variation depending on the nozzle. Also, the nozzle driving means such as a piezo element that causes ink to fly to each nozzle cannot be driven in the same state with respect to the same drive signal due to manufacturing variations and the like. The flying directions of flying ink particles are different. When the ink is attached to the nozzle portion, the variation in the flight direction of the ink particles can be corrected by cleaning the nozzle portion and removing the attached ink. However, variations in the flight direction of ink particles due to variations in manufacturing nozzles and nozzle driving means are unique to each inkjet recording apparatus, and it is very difficult to correct the flight direction of ink particles.

When the flying direction of ink particles varies in the main scanning direction of the head, white or black streaks appear in the sub-scanning direction on the paper in monochrome recording. in this case,
The white streak refers to an unrecorded portion (recording skipped portion) that occurs on paper that is normally white when adjacent dot lines are separated. The black streak refers to a darkly recorded portion that occurs on the paper due to the overlapping of adjacent dot lines. On the other hand, if the flight direction of the ink particles varies in the sub-scanning direction, white or black streaks appear in the main scanning direction on the paper in monochrome recording. Similarly, in the case of color recording, white streaks and streaks of various colors appear on the paper in the main scanning direction or the sub scanning direction depending on the direction of variation in the flight direction of ink particles.

When the white streaks, the black streaks, or the streaks of various colors are generated on the paper as described above, there is a problem that the recording image quality is deteriorated. This kind of deterioration of recorded image quality
Especially when the number of dots for recording one line is small, that is,
This was especially noticeable when the recording resolution was low.

In order to prevent the deterioration of the recording image quality, it is only necessary to narrow the allowable range of the flight direction of ink particles from each nozzle. However, if the allowable range of the flight direction of the ink particles is narrowed, the yield of the head decreases, the head becomes very expensive, and the inkjet recording apparatus as a whole becomes expensive.

Therefore, the present invention is an ink jet recording method capable of suppressing deterioration of the recording image quality and performing recording at high speed even when an inexpensive head in which flight directions of ink particles from nozzles vary. And to provide a device.

[0008]

The above-mentioned problem is solved by claim 1.
In the ink jet recording method described above, in which a head having a plurality of nozzles for ejecting ink particles is scanned in the main scanning direction to record image information on a recording medium, one dot line is ejected from the same nozzle on a recording medium. In the high image quality recording mode in which the image is recorded with higher image quality, unlike the standard recording mode in which the recording is performed on the head, the head is scanned n times and one dot line is recorded on the recording medium by the ink particles flying from the n nozzles. And a step of variably setting the line feed pitch p of the paper in the sub-scanning direction orthogonal to the main scanning direction in accordance with the value of n in the high-quality recording mode, and in the high-quality recording mode, The step of variably setting the scanning speed of the head according to the value of
The flying amount of ink particles is kept constant, and it depends on the nozzle.
And a step of setting the flight speed of the ink at different values .

According to a second aspect of the invention, the invention of the first aspect further includes the step of setting the value of n. According to the invention of claim 3, in the invention of claim 1 or 2,
When the line feed pitch of the paper in the standard recording mode is P, the line feed pitch p in the high image quality recording mode is
Is set to satisfy p = P / n.

According to a fourth aspect of the present invention, in the method of any one of the first to third aspects, the step of variably setting the scanning speed of the head in the high image quality recording mode includes
The scanning speed of the head is set to about n times the scanning speed in the standard recording mode according to the value of.

According to a fifth aspect of the invention, in any one of the first to fourth aspects of the invention, the value of n is 2 or 4 .

[0012]

According to a sixth aspect of the present invention, in the first aspect of the invention, the step of setting the ink flight speed to a different value depending on the nozzle changes the signal waveform for driving the nozzle depending on the nozzle. Set. The above object is achieved according to claim 7, wherein a head having a plurality of nozzles for ejecting ink droplets at the time of driving, the head is scanned in the main scanning direction, the image information by the ink particles fly from the driven nozzle The means for recording on the recording medium, the means for feeding the paper in the sub-scanning direction orthogonal to the main scanning direction, and the standard recording mode for recording one dot line on the recording medium by the ink particles flying from the same nozzle In contrast, in the high image quality recording mode for recording with higher image quality,
A means for selectively driving the nozzles so as to record one dot line on the recording medium with ink particles flying from n nozzles by controlling the scanning means so as to scan once; means for variably setting the line feed pitch p of the paper in the sub-scanning direction according to the value of n, the high-quality recording mode, and means for variably setting a scanning speed of the head according to the value of the n, each Ink particle flight from nozzle
The amount of ink is kept constant, and the ink jet speed is changed according to the nozzle.
It is also achieved by an ink jet recording apparatus provided with means for setting different degrees .

[0014]

According to the first and seventh aspects of the present invention, even if an inexpensive head in which the flying directions of the ink particles from the nozzles are varied is used, deterioration of the recording image quality is suppressed and high-speed recording is performed. be able to. According to the second aspect of the invention, the value of n can be arbitrarily set according to the desired recording image quality.

According to the third aspect of the invention, a high recording image quality can be realized. According to the invention described in claim 4, high-speed recording can be realized. According to the invention of claim 5, the selective driving of each nozzle can be controlled by a simple means.

[0017]

According to the invention of claim 6 , the flying speed of the ink particles can be controlled by a simple means. Therefore, according to the present invention, high recording image quality and high recording speed can be realized by a relatively inexpensive inkjet recording apparatus.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION In the first embodiment of the present invention,
Standard recording in which one dot line is recorded on a recording medium by ink particles flying from the same nozzle when image information is recorded on the recording medium by scanning a head having a plurality of nozzles that fly ink particles in the main scanning direction. Unlike the mode, in the high image quality recording mode in which recording is performed with higher image quality, the head is scanned n times and one dot line is recorded on the recording medium by the ink particles flying from the n nozzles.
Further, in the high image quality recording mode, the line feed pitch p of the paper in the sub-scanning direction orthogonal to the main scanning direction is variably set according to the value of n, and the scanning speed of the head is varied according to the value of n. Set. As a result, it is possible to suppress deterioration of the recording image quality and perform high-speed recording even with an inexpensive head in which the flight directions of ink particles from nozzles vary.

In the second embodiment of the present invention, when the head having a plurality of nozzles for ejecting the ink particles is scanned to record the image information on the recording medium, the flying amount of the ink particles from each nozzle is It is kept constant and the ink flight speed is set to a different value depending on the nozzle. Further, each dot line is recorded on the recording medium by the ink particles flying from the corresponding nozzle. As a result, it is possible to suppress deterioration of the recording image quality and perform high-speed recording even with an inexpensive head in which the flight directions of ink particles from nozzles vary.

Furthermore, as a third embodiment of the present invention,
The first and second embodiments may be combined.
In this case, the recording image quality can be further improved.

[0022]

First, a first embodiment of the ink jet recording apparatus according to the present invention will be described. The first embodiment of the inkjet recording apparatus employs the first embodiment of the inkjet recording method according to the present invention.

FIG. 1 is a block diagram showing the schematic arrangement of an ink jet recording apparatus according to this embodiment together with a host device. In FIG. 1, an inkjet recording device (hereinafter, simply referred to as a printer) 1 is connected to a host device 3 via an interface 2. The host device 3 is, for example, a personal computer having a printer driver 32 activated by application software 31.

The printer 1 generally has a central controller (CP).
U) 11, read-only memory (ROM) 12, external interface (IF) 13 that controls the interface with the host device 3, random access memory (RA)
M) 14, a mechanical interface (IF) 15 that controls the interface with the mechanical portion 21 of the printer 1, a head drive interface (IF) 16 that controls an interface with a head 25 described later, a bus 17, a paper feed motor driver 18, and a head. It consists of a feed motor driver 19, a head driver 20, and a mechanical part 21. Bus 17 is R
The OM 12, the external IF 13, the RAM 14, the mechanical IF 15, and the head drive IF 16 are connected to the CPU 11.

The mechanical portion 21 generally includes a sensor group 22 connected to the mechanical IF 18, a paper feed motor 23 driven by the paper feed motor driver 18, a head feed motor 24 driven by the head feed motor driver 19, and a head. The head 25 is driven by the driver 20. The head 25 includes a nozzle selection circuit 26 and a piezo element 27.

The CPU 11 controls the operation of the printer 1 as a whole. The ROM 12 stores in advance programs and data to be executed by the CPU 11. RAM14 is CP
It stores data and intermediate data used when the U11 executes the program. The external IF 13 notifies the CPU 11 of the image information and control information obtained via the printer driver 32 of the host device 3, and
The host device 3 is notified of a message or the like issued by the host device 3. The image information is usually temporarily stored in the RAM 14.

The mechanical IF 15 drives and controls the paper feed motor 23 via the paper feed motor driver 18 based on an instruction from the CPU 11, and the head feed motor driver 19
Drive control of the head feed motor 24 via
The detection signal from the sensor group 22 is notified to the CPU 11.
The paper feed motor 23 drives a known paper feed mechanism (not shown) to feed the paper (not shown) used as a recording medium in the sub-scanning direction at a designated line feed pitch (paper feed pitch). On the other hand, the head feed motor driver 19 drives a well-known head feed mechanism (not shown) to feed the head 25 at the instructed scanning speed in the main scanning direction. The main scanning direction is a direction orthogonal to the sub scanning direction. The sensor group 22 includes a sensor that detects a paper jam, a sensor that detects the size of the paper loaded in the printer 1, and the like, and sends a detection signal indicating the detection result to the CPU 11 via the mechanical IF 15.

The head drive IF 16 drives and controls the head 25 via the head driver 20 based on an instruction from the CPU. The head driver 20 selects a nozzle (not shown) of the head 25 to be driven via the nozzle selection circuit 26. The piezo element 27 corresponding to the selected nozzle is driven by the nozzle selection circuit 26.

Since the configuration itself of each part of the printer 1 shown in FIG. 1 can be a known one, detailed description thereof will be omitted in this specification. In other words, the present embodiment is characterized by the operation of the CPU 11 that controls the overall operation of the printer 1, and the configuration of the printer 1 is not limited to the configuration shown in FIG. It can be applied to printers of various configurations.

FIG. 2 is a diagram schematically showing the nozzle arrangement of the head 25 when the printer 1 performs color recording.
In the figure, each circle indicates one nozzle, K1 to K15 are nozzles that fly black ink, C1 to C15 are nozzles that fly cyan ink, M1 to M15 are nozzles that fly magenta ink, and Y1 to Y15. Indicates a nozzle that ejects yellow ink. The horizontal direction corresponds to the main scanning direction of the head 25, and the vertical direction corresponds to the sub-scanning direction in which the paper is fed. In this case, the nozzles are arranged in the sub-scanning direction at the same dot number intervals as the nozzle number (dot number) per color. Further, the nozzles of each color are arranged in the sub-scanning direction at a pitch corresponding to a predetermined resolution. That is, in FIG. 2, the number of nozzles for each color of the head 25 is 16, and the nozzle groups for each color are arranged at 16-dot intervals in the sub-scanning direction. The colors of the color inks other than black are not limited to yellow, magenta and cyan.

3 to 5 are diagrams for explaining the recording operation in this embodiment. FIG. 3 is a diagram for explaining the operation in the standard recording mode, and FIGS. 4 and 5 are diagrams for explaining the operation in the high image quality recording mode, respectively. For convenience of explanation,
FIGS. 3 to 5 show only recording of 16 dots corresponding to the number of nozzles per color (= 16), and recording with black ink will be described as an example. Since recording with inks of other colors is performed in the same manner, description thereof will be omitted. Furthermore, it is assumed that the ink jetting direction from the bottommost nozzle is below the design value, and the ink jetting direction from the second lowest nozzle is above the design value.

The line feed pitch P in the standard recording mode is
It is assumed to be 16 dots. In this case, since one dot line is recorded by the same nozzle of the head 25, when the head 25 is scanned once in the main scanning direction, the bottom and the second from the bottom shown by black circles in FIG. The nozzle is driven and the dot at the corresponding position is recorded. As described above, in this case, the flying directions of the ink from the bottommost nozzle and the second lowest nozzle are different from each other, so the dots recorded on the paper are indicated by black circles in FIG. 3B. become,
White streaks occur in the main scanning direction. Although illustration is omitted, on the contrary, if the flying directions of the ink from the bottommost nozzle and the second lowest nozzle are different from each other, the dots printed on the paper partially overlap. , The darkly recorded portions become black streaks and appear in the main scanning direction.

In the high image quality recording mode, the line feed pitch p is set to be smaller than the line feed pitch P in the standard recording mode so that the white and black lines are inconspicuous, and recording with higher image quality than the standard recording mode is possible. To do. In this embodiment, the high image quality recording mode has two modes, a fine recording mode and an ultrafine recording mode. The line feed pitch p is set to 8 dots in the fine recording mode, and the line feed pitch p is set to 4 dots in the super fine recording mode.

In the fine recording mode, when the head 25 is scanned once in the main scanning direction, the bottom and second nozzles indicated by black circles in FIG. That is, half the amount of image information recorded in the standard recording mode is recorded. As described above, in this case, the flying directions of the ink from the bottommost nozzle and the second lowest nozzle are different from each other, so that white stripes appear on the printed paper in the main scanning direction. Next, the paper is fed in the sub-scanning direction by the line feed pitch p1 of 8 dots, and the head 25 is scanned again in the main scanning direction.
In this case, the 9th and 10th nozzles from the bottom, which are located 8 dots (line feed pitch p1) above in the sub-scanning direction from the bottom and second nozzles from the bottom shown by black circles in FIG. When driven, dots at corresponding positions, that is, the remaining image information is recorded. For convenience of explanation, it is assumed that the ink ejection directions from the ninth and tenth nozzles from the bottom are substantially the same as the design values, but at least the ejection directions of the ink from the bottommost nozzle and the second nozzle from the bottom. Since it is very unlikely that they are exactly the same, it does not necessarily have to be as designed. Therefore, the dots printed on the paper by the above-described two scans are shown by black circles in FIG.
It can be seen that the image quality is improved as compared with the case of (b).

In the super fine recording mode, when the head 25 is scanned once in the main scanning direction, the bottom and second nozzles from the bottom shown by black circles in FIG. Dots, that is, image information of 1/4 the amount of image information recorded in the standard recording mode is recorded. As described above, in this case, the flying directions of the ink from the bottommost nozzle and the second lowest nozzle are different from each other, so that white stripes appear on the printed paper in the main scanning direction. Next, the paper is fed in the sub-scanning direction by the line feed pitch p2 of 4 dots, and the head 25 is scanned once again in the main scanning direction. In this case, the 5th and 6th nozzles from the bottom, which are 4 dots (line feed pitch p2) above in the sub-scanning direction from the bottom and 2nd nozzles from the bottom shown by black circles in FIG. When driven, dots at corresponding positions, that is, the amount of image information that is ⅓ of the remaining image information is recorded. For convenience of explanation, it is assumed that the ink ejection directions from the fifth and sixth nozzles from the bottom are substantially the same as the designed values, but at least the ejection directions of the inks from the bottom and second nozzles from the bottom. Since it is very unlikely that they are exactly the same, it does not necessarily have to be as designed. Next, the paper is further fed in the sub-scanning direction by a line feed pitch p2 of 4 dots, and the head 25 is scanned again in the main scanning direction. In this case, the 9th and 10th nozzles from the bottom, which are located 4 dots (line feed pitch p2) above in the sub-scanning direction from the 5th and 6th nozzles from the bottom shown by black circles in FIG. 5C, are driven. The dot at the corresponding position, that is, 1/2 of the remaining image information
Image information is recorded. The ink jet directions from the ninth and tenth nozzles from the bottom are assumed to be substantially the same as designed values for convenience of description, but at least the second and the bottom nozzles from the bottom or the fifth and sixth nozzles from the bottom. Since it is very unlikely that it is the same as the flight direction of the ink from the second nozzle, it does not necessarily have to be the designed value.
Then, the paper is further fed in the sub-scanning direction by the line feed pitch p2 of 4 dots, and the head 25 is scanned again in the main scanning direction. In this case, the 13th and 14th nozzles from the bottom, which are located 4 dots (line feed pitch p2) above in the sub-scanning direction from the 9th and 10th nozzles from the bottom, which are indicated by black circles in FIG. 5D, are driven. The dot at the corresponding position,
That is, the remaining image information is recorded. The ink jet directions from the 13th and 14th nozzles from the bottom are almost the same as design values for convenience of explanation, but at least the 2nd and 6th nozzles from the bottom, and the 5th and 6th nozzles from the bottom. Since it is very unlikely that the ink ejection direction from the 9th nozzle or the 9th and 10th nozzles from the bottom is exactly the same, it does not necessarily have to be the designed value. Therefore, the dots printed on the paper by the above four scans are shown by black circles in FIG. 5E, and it is understood that the image quality is improved as compared with the case of FIG. 3B.

By the way, in the high image quality recording mode, the image quality can be greatly improved as compared with the standard recording mode by using the head 25 including the nozzles having a slight variation in the ink jet direction. The number of scans increases according to the line feed pitch p. Therefore, in the high image quality recording mode, when the head 25 is scanned n times and one dot line is recorded on the paper by the ink particles flying from the n nozzles, it is orthogonal to the main scanning direction depending on the value of n. In addition to variably setting the line feed pitch p of the paper in the sub-scanning direction,
The scanning speed of the head 25 is variably set according to the value of n.
Specifically, when the paper line feed pitch in the standard recording mode is P, the line feed pitch p in the high image quality recording mode is set to satisfy p = P / n, and the head 25
The scanning speed of is set to about n times the standard recording mode. As a result, even if the number of scans of the head 25 for one dot line is increased as compared with that in the standard recording mode, high-quality recording can be realized while maintaining the recording speed at about the same level as in the standard recording mode.

Since a known method can be used for the image information division processing itself for dividing and recording the image information in the high image quality recording mode, description thereof will be omitted. Further, when the head 25 is scanned a plurality of times to record one dot line, it goes without saying that recording may be performed only on the forward path in the main scanning direction of the head 25 or may be performed on both the forward and return paths. . If you want to record both forward and backward,
It is necessary to reverse the order of image information for each line,
A well-known method can also be used for this reversal process itself, and therefore its description is omitted.

Further, the high image quality recording mode is not limited to the two modes of the fine recording mode and the superfine recording mode, and three or more kinds of high image quality recording modes may be provided. Next, the operation of this embodiment will be described with reference to the flowchart shown in FIG. FIG. 6 corresponds to the operation of the CPU 11 shown in FIG.

In FIG. 6, when the printer driver 32 of the higher-level device 3 is activated and the control information including the recording mode and the image information to be recorded are supplied from the printer driver 32 to the external IF 13 of the printer 1, the CPU 11 executes step S11. Determines whether the recording mode is the standard recording mode or the high image quality recording mode. When the recording mode is the standard recording mode, the line feed pitch P of the paper is set in step S12, and the head scanning speed hp1 corresponding to the line feed pitch P is set in step S13. Step S14
Develops the image information to be recorded on the RAM 14.
In this case, the image information is developed on the RAM 14 according to the recording order so that one dot line is printed by the same nozzle of the head 25 by one scan of the head 25.
The line feed pitch P is, for example, 16 dots.

On the other hand, when the recording mode is the high image quality recording mode, it is determined in step 15 whether the recording mode is the fine recording mode or the ultrafine recording mode. In the fine recording mode, the line feed pitch p1 (p1
<P) is set, and the head scanning speed hp2 (hp2> hp1) according to the line feed pitch p1 is set in step S17. In step S18, the image information to be recorded is set to R
Deploy on AM14. In this case, as for the image information, one dot line is obtained by scanning the head 25 a plurality of times.
RA is recorded by a plurality of nozzles in accordance with the recording order and the number of scans of the head 25 with respect to one dot line.
Deployed on M14. The line feed pitch p1 is, for example, 8 dots, the head 25 scans a 1-dot line twice, and the head scanning speed hp2 is about twice the speed hp1.

In the case of the super fine recording mode, step S19
The line feed pitch p2 (p2 <p1) of the paper is set by and the head scanning speed h corresponding to the line feed pitch p2 in step S20.
p3 (hp3> hp2) is set. Step S21
Develops the image information to be recorded on the RAM 14.
In this case, the image information is stored in the RAM 14 in accordance with the recording order and the number of scans of the head 25 with respect to one dot line so that one dot line is printed by a plurality of nozzles of the head 25 by a plurality of scans of the head 25. Be expanded.
The line feed pitch p2 is, for example, 4 dots, and the head 25
Is scanned four times with respect to one dot line, and the head scanning speed hp3 is about 4 times as fast as hp1.

In the case of the standard recording mode, a step S22 sequentially reads the image information from the RAM 14 and, according to the image information, the head driver 20 via the head drive IF 16.
And the head feed motor driver 19 via the mechanical IF 15 to record the image information on the paper by one scan of the head 25. Step S2
When recording of one line is completed, 3 controls the paper feed motor driver 18 via the mechanical IF 15 to feed the paper in the sub-scanning direction by the line feed pitch P. Step S24
Determines whether or not the next line to be recorded exists, and if the determination result is YES, the process proceeds to step S1 above.
Return to 4.

In the case of the fine recording mode, a step S22 sequentially reads the image information from the RAM 14 and, according to the image information, the head driver 20 via the head drive IF 16.
By controlling the head feed motor driver 19 and the paper feed motor driver 18 via the mechanical IF 15, the paper feed for one line feed pitch p1 and the scanning of the head 25 for the image information on the paper are performed. To record. In step S23, when the recording of one line is completed, the mechanism I
By controlling the paper feed motor driver 18 via F15, the paper is fed by the line feed pitch p1 in the sub-scanning direction. A step S24 decides whether or not there is a next line to be recorded, and if the decision result is YES, the process returns to the step S14.

In the case of the super fine recording mode, step S22
Sequentially reads the image information from the RAM 14, and according to the image information, the head driver 2 via the head drive IF 16.
By controlling 0 and controlling the head feed motor driver 19 and the paper feed motor driver 18 via the mechanical IF 15, the image information is obtained by feeding the paper by the line feed pitch p2 three times and scanning the head 25 four times. Record on paper.
In step S23, when the recording of one line is completed, the paper feed motor driver 18 is controlled via the mechanical IF 15 to feed the paper in the sub-scanning direction by the line feed pitch p2. A step S24 decides whether or not there is a next line to be recorded, and if the decision result is YES, the process returns to the step S14.

If the decision result in the step S24 is NO, the process ends. As a well-known printer technology,
There are existing printers having a recording mode called a so-called draft mode. This draft mode is provided for the purpose of shortening the recording time. The recording speed is set to, for example, twice that in the standard recording mode, and the amount of image information to be recorded is thinned to, for example, half or less and then recorded on paper. For this reason, the resolution of the image information to be recorded is less than half of that in the standard recording mode, and the recording image quality is greatly deteriorated. However, this mode is convenient when you want to know the outline of the recording result quickly.

The high image quality recording mode is completely different from the draft mode. In the draft mode, the thinned image information is recorded, so that the recording image quality is significantly reduced as compared with the standard recording mode. On the other hand, in the high image quality recording mode, since the image information of one dot line is divided and recorded by a plurality of nozzles, the image information finally recorded is not thinned. Therefore, the recording image quality does not deteriorate due to the division of the image information, and when there is a variation in the ink ejection direction from the nozzles as described above, the recording image quality is improved rather than in the standard recording mode.

Next, a second embodiment of the ink jet recording apparatus according to the present invention will be described. The second embodiment of the inkjet recording apparatus employs the second embodiment of the inkjet recording method according to the present invention. FIG. 7 is a diagram for explaining the relationship between the flight speed of ink particles and the flight direction. This figure shows a part of the results of experiments by the inventors of the present invention with respect to two typical types of ink, and the flight direction shows the deviation from the design value as an angle. As can be seen from the figure, according to the experiments by the inventors,
It was confirmed that even with the same nozzle, the higher the flight speed of ink particles, the smaller the variation in the flight direction with respect to the design value. Therefore, in the present embodiment, the flying speed of the ink particles from the nozzles is controlled to suppress the deterioration of the recording image quality due to the variation in the flying direction. Specifically, in order to record one dot line with the same nozzle, the nozzles are selectively driven by drive waveforms with different voltage change ratios that contribute to the flight of ink particles, without changing the flight amount of ink particles. Recording is performed by changing only the flight speed and consequently changing the flight direction of ink particles from the same nozzle. As a result, high recording image quality can be achieved even with a head having variations in the flight direction of ink particles from the nozzles. In addition, high-speed recording is possible without sacrificing recording speed for improving recording image quality.

FIG. 8 is a block diagram showing the construction of the main part of the second embodiment of the ink jet recording apparatus according to the present invention. For convenience of explanation, it is assumed that the schematic configuration of the second embodiment of the inkjet recording apparatus is the same as that in FIG. In the following description, the circuit shown in FIG. 8 is described as being added to the nozzle selection circuit 26 shown in FIG. 1. However, even if it is connected to the outside of the nozzle selection circuit 26, it is added to the head driver 20. Even if connected to the outside of the head driver 20,
Alternatively, it goes without saying that they may be provided separately in the head driver 20 and the nozzle selection circuit 26.

The circuit shown in FIG. 8 is a drive waveform generation circuit 41.
To 43, analog switches 44-1 to 44-n, random number generator 47, registers 48 and 50, and shift register 4
It consists of 9. The drive waveform generation circuits 41 to 43 include a CPU
The trigger signal tR1 from 11 is supplied to the random number generator 4
A trigger signal tR2 from the CPU 11 is supplied to 7. The latch signal LT from the CPU 11 is supplied to the registers 48 and 50. The shift register 49 has a CP
Clock signal CLK from U11 and head driver 20
The image information DATA to be recorded from is supplied.

The drive waveform generation circuits 41 to 43 respectively generate three different drive waveforms w1 to w3 in response to the trigger signal tR1. These drive waveforms w1 to w3
Are generated in order to cause the ink particles to fly at different flight velocities. The drive waveforms w1 to w3 output from the drive waveform generation circuits 41 to 43 are supplied to all the analog switches 44-1 to 44-n, respectively.

The shift register 49 has a clock signal CL.
Image information DAT corresponding to the number of nozzles of the head 25 in response to K
Take in A. When the shift register 49 fetches the image information DATA for the number of nozzles of the head 25, the image information DATA is temporarily stored in the register 50 in response to the latch signal LT. On the other hand, the 3-bit random number generated from the random number generator 47 in response to the trigger signal tR2 is also temporarily stored in the register 48 in response to the latch signal LT. A 3-bit random number is generated such that only 1 bit has the logical value "1".

The 4-bit outputs of the registers 48 and 50 are supplied as control signals to the analog switches 44-1 to 44-n. Specifically, the 3-bit output of the register 48 is supplied to the select terminals Sel of the analog switches 44-1 to 44-n, and the analog switches 44-1.
-1 to 44-n are drive waveforms w1 to w3 depending on which 1-bit logical value of the 3-bit output is "1".
One of the corresponding drive waveforms is selectively output. or,
The 1-bit output of the register 50 is for each analog switch 4
4-1 to 44-n are supplied to enable terminals En and
When the logical value of the bit output is "1", the analog switches 44-1 to 44-n are in the operating state. That is, if the logical value of the 1-bit output of the register 50 is “0”,
Each of the analog switches 44-1 to 44-n is in a non-operating state, and none of the drive waveforms w1 to w3 is output. On the other hand, when the logical value of the 1-bit output of the register 50 is "1", the analog switches 44-1 to 44-
n becomes the operating state, and any one of the drive waveforms w1 to w3 has a drive waveform of each analog switch 44-1 to 44-n.
Is output and supplied to the corresponding piezo element 27.
Since each piezo element 27 is supplied with a different drive waveform according to the random number generated by the random number generator 47, it is possible to change the flying speed of the ink particles from the nozzle while keeping the flying amount of the ink particles constant. You can

In this embodiment, since the means for driving the nozzle is the piezo element 27, the difference in the driving waveform for changing the flying speed of the ink particles from the nozzle is the voltage per unit time when the ink particles fly. The change rate, that is, the slope of the drive waveform is reflected. FIG. 9 is a signal waveform diagram for explaining the operation of the second embodiment. In the figure, the clock signal CLK, the image information DATA, the latch signal LT, the trigger signal tR1, and the drive waveforms w1 to w described with reference to FIG.
Timing 3 is shown.

Although three types of drive waveforms are used in this embodiment, the number of types of drive waveforms may be two or four or more. Further, in the present embodiment, the drive waveform is selected based on the random number, but it is not always necessary to use the random number, and the drive waveform may be regularly selected. However, in order to effectively suppress the deterioration of the recording image quality due to the variation in the flight direction of ink particles from the nozzles, it is desirable to select the drive waveform based on a random number.

It is also possible to combine the first and second embodiments described above. That is, in the inkjet recording method and apparatus according to the present invention, the first and second embodiments of the inkjet recording method and apparatus described above are used in combination. Thereby, the recording image quality can be further improved.

The present invention has been described above with reference to the embodiments.
It is needless to say that the present invention is not limited to the above embodiments, and various improvements and modifications can be made within the scope of the present invention.

[0057]

According to the first and seventh aspects of the present invention, the deterioration of the recording image quality is suppressed even when an inexpensive head in which the flight direction of ink particles from nozzles varies is used, and
Recording can be performed at high speed.

According to the second aspect of the invention, the value of n can be arbitrarily set according to the desired recording image quality. According to the invention of claim 3, high recording image quality can be realized.
According to the invention described in claim 4, high-speed recording can be realized.

According to the fifth aspect of the invention, the selective driving of each nozzle can be controlled by a simple means .

According to the invention described in claim 6 , the flying speed of the ink particles can be controlled by a simple means. Therefore, according to the present invention, high recording image quality and high recording speed can be realized by a relatively inexpensive inkjet recording apparatus.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a first embodiment of an inkjet recording apparatus according to the present invention together with a host device.

FIG. 2 is a diagram schematically showing an arrangement of nozzles of a head.

FIG. 3 is a diagram for explaining an operation in a standard recording mode.

FIG. 4 is a diagram for explaining an operation in a fine recording mode.

FIG. 5 is a diagram for explaining an operation in a super fine recording mode.

FIG. 6 is a flowchart for explaining the operation of the first embodiment.

FIG. 7 is a diagram illustrating a relationship between a flight speed of ink particles and a flight direction.

FIG. 8 is a block diagram showing a configuration of a main part of a second embodiment of an ink jet recording apparatus according to the present invention.

FIG. 9 is a signal waveform diagram for explaining the operation of the second embodiment.

[Explanation of symbols]

1 printer 2 interface 3 Host device 11 CPU 12 ROM 13 External IF 14 RAM 15 Mechanical IF 16 head drive IF 17 bus 18 Paper feed motor driver 19 Head feed motor driver 20 head driver 21 Mechanical part 22 sensor group 23 Paper feed motor 24 head feed motor 25 heads 26 Nozzle selection circuit 27 Piezo element 41-43 Drive waveform generation circuit 44-1 to 44-n analog switch 47 Random number generator 48,50 registers 49 shift register

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-7-101062 (JP, A) JP-A-4-366645 (JP, A) JP-A-8-90776 (JP, A) JP-A-7- 61078 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B41J 2/01 B41J 2/045-2/055

Claims (7)

(57) [Claims] 1. A plurality of nozzles for ejecting ink particles are provided.
Image information on the recording medium by scanning the head in the main scanning direction.
In the inkjet recording method for recording on the body, 1 dot line to ink particles flying from the same nozzle
Unlike the standard recording mode that records on a recording medium,
In the high image quality recording mode, which prints with higher image quality, the head
Scan n times to scan 1 dot line from n nozzles.
Recording on a recording medium with flying ink particles, In the high image quality recording mode, in the main scanning direction depending on the value of n.
The line feed pitch p of the paper in the sub-scanning direction orthogonal to
Setting process, In the high image quality recording mode, the head is changed according to the value of n.
Variably setting the scanning speed of, The amount of ink particles flying from each nozzle is kept constant, and
Set the ink flight speed to a different value depending on the nozzle
And the process An inkjet recording method including: 2. The method further comprises the step of setting the value of n.
The inkjet recording method according to claim 1. 3. The line feed pitch p in the high image quality recording mode is set to satisfy p = P / n, where P is the line feed pitch of the paper in the standard recording mode. 2. The inkjet recording method of 2. 4. The step of variably setting the scanning speed of the head in the high image quality recording mode sets the scanning speed of the head to about n times the scanning speed in the standard recording mode according to the value of n. The ink jet recording method according to any one of claims 1 to 3. 5. The ink jet recording method according to claim 1, wherein the value of n is 2 or 4. 6. The flight speed of ink according to the nozzle
The process of setting different values drives the nozzles according to the nozzles.
The moving signal waveform is set to a different waveform.
Inkjet recording method. 7.Multiple nozzles that fly ink particles when driven
Head with cheat When, Nozzles driven by scanning the head in the main scanning direction
Image information is recorded on the recording medium by ink particles flying from the
Scanning means for recording, Line feed in the sub-scanning direction orthogonal to the main scanning direction
Means and 1 dot line to ink particles flying from the same nozzle
Unlike the standard recording mode that records on a recording medium,
In the high image quality recording mode for recording with higher image quality,
The scanning means is controlled so that the scanning is performed n times.
Ink particles that fly the try line from n nozzles
Means for selectively driving nozzles for recording on a recording medium
When, In the high image quality recording mode, in the sub-scanning direction depending on the value of n.
Means for variably setting the line feed pitch p of paper to In the high image quality recording mode, the head of the head is changed according to the value of n.
Means for variably setting the scanning speed, The amount of ink particles flying from each nozzle is kept constant, and
Set the ink flight speed to a different value depending on the nozzle
And an inkjet recording device.