JPH02147246A - Strain correction apparatus of ink jet printer - Google Patents

Abstract

PURPOSE:To set a correction coefficient most suitable for an individual factor by correcting three kinds of strain factors according to algorithms most suitable for the respective factors. CONSTITUTION:An exciting amplifier 2 vibrates the piezoelectric element in a nozzle 1 and divides injected ink into ink particles 7 while the ink particles 7 are charged in a charge electrode 3 to receive deflection during the flight through the electrostatic field between a positive deflection electrode 5 and a negative deflection electrode 6 and a character is formed on an object 9 to be printed. The correction coefficients to various strain factors are preliminarily stored in an ROM 21. When the height of a character to be printed is inputted from an input/output apparatus 24, an MPU 19 operates stepped data according to each of the correction coefficients in the ROM 21 to store the operated data in a stepped wave RAM 14 through a selector 15 by writing processing. Stepped wave data corrected in strain with respect to one strain factor according to the algorithm concerned is formed and corrected according to the algorithm concerned with respect to the second and third strain factors. Since stepped wave data in which three kinds of all of the factors are incorporated is formed, printing is confirmed using this stepped wave data. Since the setting of the correction coefficient can be altered at every factor, a proper correction coefficient can be set.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a device for reducing printing distortion in an inkjet printer using a charging control method.

[Conventional technology]

In the conventional apparatus, as described in Japanese Patent Publication No. 53-22019, one correction coefficient is selected for the printed result, instead of changing the correction coefficient for each distortion factor.

[Problem to be solved by the invention]

In the above-mentioned conventional technology, it is difficult to set an optimal correction coefficient because it is not possible to independently correct each distortion factor.

An object of the present invention is to make it possible to set the most suitable correction coefficient for each individual factor.

[Means to solve the problem]

The above object is achieved by making it possible to correct three types of distortion factors using an algorithm most suitable for each factor.

[Effect]

First, staircase wave information is created by distortion-correcting one distortion factor using a corresponding algorithm.For a zero-order second distortion factor, the staircase wave information is corrected using a corresponding algorithm. Next, the staircase wave information is corrected using an algorithm corresponding to the third distortion factor. In this way, staircase wave information incorporating all three types of factors is created, and printing is confirmed using this staircase wave information.

This makes it possible to change the setting of the correction coefficient for each factor, thereby making it possible to set an appropriate correction coefficient.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

1 is a nozzle, into which pressurized ink is fed from the left and the ink is ejected. The excitation amplifier 2 vibrates the electrostrictive element in the nozzle 1 to regularly form ejected ink particles into particles. The ink particles 7 are charged in the charging electrode 3, and depending on the amount of charge, the ink particles 7 are deflected onto the printing object 9 while flying in an electrostatic field composed of ten deflection electrodes 5 and one deflection electrode 6. Form the characters as shown. Further, unused ink particles are collected in the gutter 8 and reused. The high voltage power supply 4 is for generating an electrostatic field. The video amplifier 12 is for amplifying the charging signal, and the D/A converter 13 is for converting the digital charging signal into an analog signal. Staircase wave RAM1
4 is a memory storing a plurality of types of staircase waves subjected to various distortion corrections, and a selector 15 is a RAM from the lMPU 19.
This is for switching between access and RAM access from the vertical dot counter 161 and the previous and subsequent dot information registers 17. The MPU 19 is for controlling the entire inkjet, the RAM 20 is a memory element that can be read and written as the program progresses, and the NC 22 is a group of circuits from which a charging signal is generated. The pass line 23 is a signal line that transmits commands from the MPU 19. The input/output device 24 has various input/output functions such as inputting and displaying print data. ROM21 is an element that stores programs and data.

Next, detailed operation of the present invention will be explained.

Correction coefficients for various distortion factors are stored in the ROM 21 in advance. Immediately after the power is turned on or when the print character height etc. are input from the input/output device 24, the MPU
19 calculates and writes staircase wave data into one staircase wave RAM l/1 via the selector 15 according to the correction coefficient in the ROM 21. The processing flow in this case is explained in the second
As shown in the figure. BOXNα5 in FIG. 2 is indicated as A5. The same shall apply hereinafter. The flow shown in FIG. 2 will be explained one by one. A5 indicates that a correction coefficient is incorporated to remove distortion due to the influence of preceding charged particles. Figure 3 shows the influence of the preceding electric particles. An example of the distortion is shown above the column of letters T in the lower row of FIG. To explain FIG. 3, a positive polarity charging signal is applied to the video amplifier 12. A charge proportional to this voltage is induced in the ink particle C. Ink particle S is the preceding particle, and ink particle a is the preceding particle. NQa, b, and c of the ink particles are also shown in FIG. 4. In this example, 2 The preceding particles are considered. In reality, it will be further influenced by the preceding particles, but for practical purposes, up to two preceding particles are sufficient. The effect of the preceding particles is that the amount of charge charged to ink particle C is reduced due to the amount of charge on ink particles a and b. For this reason.

If the particles a and b are charged, it is necessary to increase the amount of charge on the ink particles C. Therefore, the correction equation in this case is expressed by equation (1).

...Formula (1) ■n: Intermediate value of voltage applied to the corresponding ink particle Vns:
Standard voltage for n stages v(nt)s: Standard voltage for (n 1) stage, that is, standard voltage for the previous preceding particle y(nz)s: Standard voltage for (n-2) stages In other words, standard voltage Kb for the two preceding particles: correction coefficient Ka when one preceding particle exists: correction coefficient when two preceding particles exist.Based on this formula (1), Create staircase waves for four types of combinations that occur depending on the presence or absence of a and b.

Store it in the staircase wave RAM. This process is the AI shown in Figure 2.
It is O.

Next, the process moves to A20 in FIG. 2, and the electrostatic interference correction coefficient between adjacent ink particles is taken in. This is a so-called correction of distortion due to Coulomb repulsion during flight, and is particularly likely to occur at the ends of a continuous group of charged particles. An example of distortion is shown in FIG.

Figure 5 shows the state of electrostatic interference during flight. Ink particles d-j are continuous particles on the upper stage side, and in particular, d repulses against e and receives a force in the direction of the arrow. Also, j repels i and receives a force in the direction of the arrow. For this reason, it can be estimated that distortion occurs as shown in FIG. As in this example, one nozzle can
When printing in columns, there is a gap of two dots in the Y direction between ink particles C and d, so there is little repulsion between d and 0. Therefore, it is more reasonable to consider that there are no ink particles in front of d. Therefore, the algorithm for electrostatic interference is to correct ink particles that have no charged particles in the front and have charged particles in the rear (termed d) to increase the amount of charge. Also, for ink particles that have charged particles in the front and do not exist in the rear (terminal j), the amount of charge is corrected to decrease. The correction equations in this case are expressed by equations (2) and (3).

Equation (2) is for ink droplet d, and equation (3) is for ink droplet j.

V:: Intermediate value of voltage applied to the corresponding ink droplet vll: Value obtained by equation (1) -: Correction coefficient in the state of ink droplet d -: Ink droplet j Based on this algorithm and equation, The staircase wave data obtained by AIO in Figure 2 will be corrected. This process is A25. After completing the creation of all staircase waves according to A30's judgment,
Enter A35.

Next, the third factor, air resistance distortion, is corrected. The correction coefficient is read in at A35 in FIG. Next, at A40, one step wave correction is performed in consideration of air resistance. Figure 4 shows an example of distortion due to air resistance. Air resistance distortion tends to occur in isolated ink particles. The ink droplet M in FIG. 5 is isolated.

Due to air resistance, the flight speed of the ink particles is lower than that of other ink particles,
As a result, it is considered that the amount of deflection becomes larger than a predetermined value. Therefore, as a correction algorithm, if there are no printing particles before or after the corresponding particle, the amount of charge of the corresponding ink particle is reduced. The correction formula in this case is formula (4
).

V = V--V-・□ Mv company = final applied voltage V to the corresponding ink particle: Formula (2
) or the value obtained from equation (3) KM: Correction coefficient for the state of the ink particles Based on this algorithm and equation, the step wave data obtained at A25 in Figure 2 is corrected. This process is A40. . When the creation of all staircase waves is completed based on the judgment in A45, the creation of staircase wave data in consideration of the distortion correction coefficient according to the present invention is completed.

Next, the actual printing operation will be explained. It is assumed that the printing object 9 is moving in the direction of the arrow and moving relative to the nozzle. It is assumed that the content to be printed is input in advance from the input device 24. When it is time to start printing, the MPU 19 sequentially takes out CG data from a character generator (hereinafter referred to as CG) stored in the ROM 21 and passes it to the NC 22. The NC 22 determines the presence/absence of dots from the supplied CG data and outputs a dot presence/absence signal. This signal enters the G terminal of the selector 15. If this G is LOW, there is a printing dot, and H
If it is ``high'', there is no printing dot. Furthermore, the NC 22 increments the vertical dot counter 16. The vertical dot counter 16 is for advancing the staircase wave stored in the staircase wave RAM 14 one step at a time from the lowest one toward the higher one.

This is a register that indicates whether or not charged particles exist in the particles before and after the ink particles used for printing.
Assuming that the particle about to be charged is C, a
, b, dl This indicates whether or not charged particles exist at e. These two types of information, that is, the information from the vertical dot counter 16° and around 16° dot information register 17 are given to the staircase wave RAM 14 from the port (2) of the selector 15.

Based on the result, a digital signal corresponding to the voltage level of the charging signal applied to the corresponding ink droplet is extracted from the output of the staircase wave RAM 14. Thereafter, this digital charging signal is converted into an analog signal by a D/A converter 13, amplified by an AMP 12, and charged to ink particles by a charging electrode 3. As shown in FIG. 5, while the charged particles fly between the ten deflection electrodes 5 and the one deflection electrode
As a result of being deflected in the direction, as shown in FIG. 1, it can be attached to the printing object sensor 9 that moves relatively, and printing can be performed.

〔Effect of the invention〕

According to the present invention, since distortion correction coefficients can be set for each distortion factor, more appropriate distortion correction can be performed and printing quality can be improved.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of the present invention, FIG. 2 is a processing flow diagram of the present invention, FIG. 3 is a diagram showing the influence of preceding charged particles, FIG. 4 is a diagram showing an example of printing distortion, FIG. 5 is a diagram showing the flight state of ink particles within the deflection electrode. DESCRIPTION OF SYMBOLS 1... Nozzle, 2... Excitation amplifier, 3... Charged electrode, 4... High voltage power supply, 5... Deflection electrode, 6...
- Deflection electrode, 7... Ink particle, 8... Gutter, 9
...Printed object, 12...Video amplifier, 13...
D/A converter, 14... Staircase wave RAM, 15...
・Selector, 16... Vertical dot counter, 17...
Front and rear dot information registers, 19...MPU, 20...
・RAM, 21...ROM, 22...NC123・
...Pass line, 24...I/O device. Figure 1 Section 2 Figure 7'111A Figure Figure ○K

Claims (1)

[Scope of Claims] 1. Pressurized ink is ejected from a nozzle, the nozzle is vibrated at a constant frequency, the ink is turned into particles at a constant synchronization, and a step-wave charging signal is applied to the charged electrodes. By imparting an electric charge to the ink particles and causing the charged particles to fly through a deflection electric field, they are deflected in the Y direction, and the printed object is moved relative to the deflection in the Y direction, thereby printing characters. In an inkjet printer that creates
The present invention has an algorithm means for alleviating distortion due to the influence of preceding charged particles, an algorithm means for alleviating distortion due to electrostatic interference between ink particles, and an algorithm means for alleviating distortion due to air resistance experienced by flying ink particles. 1. A distortion correction device for an inkjet printer, comprising means for integrating a plurality of algorithm means into one type of charging signal. 2. In claim 1, there is provided a means for recognizing the charging state of a plurality of preceding particles and the charging state of a plurality of subsequent particles with respect to an ink particle that is about to be charged, and a means for recognizing the charging state of a plurality of subsequent particles, and As a means of strain relaxation, there is an algorithm that increases the amount of charge on ink particles by a specific ratio when the preceding particle is present, and as a means of strain relaxation due to electrostatic interference between ink particles, there is no subsequent particle and only the preceding particle is present. An algorithm that reduces the amount of charge on ink particles at a specific ratio when there is an algorithm that increases the amount of charge on ink particles at a specific ratio when there are no leading particles and a trailing particle exists, and an algorithm that increases the amount of charge on ink particles at a specific ratio when there are no leading particles and there are following particles. As a means for alleviating distortion, it has an algorithm that reduces the amount of charge on an ink droplet at a specific ratio when no preceding particles are present, and has means for integrating these multiple algorithm means into one system of charging signals. A distortion correction device for an inkjet printer, which is characterized by: 3. The distortion correction device for an inkjet printer according to claim 2, characterized by having an algorithm that eliminates the influence of preceding particles or subsequent particles depending on the dot position where the charged particle is placed.