JPH06262766A - Character height control device of ink jet printer - Google Patents

Abstract

PURPOSE:To prevent the deterioration in printing quality due to the change of a character height input value and to print a small character of high quality by controlling the height of a printed character by combining change voltage and deflection voltage to change them at a time of printing. CONSTITUTION:Pressurized ink is emitted from a nozzle 32 and this nozzle 32 is vibrated at a constant cycle to pulverize the ink at the constant cycle and graded wave like charge voltage is applied to a charge electrode 33 to apply charge to an ink particle and the charged particle is allowed to fly within the deflection electric field formed by deflection electrodes 37, 38 to be vertically deflected and an object 42 to be printed is relatively moved in the direction almost right-angled to the vertical deflection of the ink particle to form a character on the object 42 to be printed. In this ink jet printer, charge voltage and deflection voltage are combined to be changed at a time of printing to control the height of a printed character. As a result, the deterioration of printing quality due to the change of a character height input value is prevented and a small character of high quality can be printed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a character height control device for an ink jet printer according to a charging control system.

[0002]

2. Description of the Related Art In a conventional apparatus, the deflection voltage and the lowest charging voltage are kept constant to reduce the inter-charging voltage, or the staircase charging voltage is kept constant to change the deflection voltage. The character height was controlled.

[0003]

Generally, in an ink jet printer, distortion is corrected because printing distortion occurs due to mutual interference between charged ink particles, air resistance during ink flight, and the like. This distortion correction eliminates print distortion by correcting the charging voltage in advance for a distorted dot. The problem of controlling the character height only by controlling the charging voltage is that when the character height is large or small, the charged electric charge amount of the charged ink particles is changed. Therefore, there is a problem that the print quality varies depending on the character height. This is not a big problem when the change range of the character height is small, but becomes large when the change range is large and the distortion becomes serious. As a means to solve this, the range from the maximum to the minimum of the character height is divided into several ranges, each of which has distortion correction data, and the character height to be printed with one distortion correction data However, there is a problem in that the amount of data for distortion correction and the time for creating and examining the data for distortion correction are twice or three times as long as the conventional method. Another problem in controlling the character height by changing the deflection voltage is that the deflection voltage becomes smaller when the character height is made smaller, so that the lowest charged ink particles can obtain sufficient deflection. However, it is impossible to print because it collides with a gutter that collects unused ink particles, and printing cannot be performed. An object of the present invention is to improve the above-mentioned problems and improve print quality.

[0004]

[Means for Solving the Problem] When changing the character height,
It has means for changing both the deflection voltage and the charging voltage.

Further, when the character height is reduced,
When the deflection voltage is decreased, the lowest charged ink particles collide with the unused ink particle recovery gutter.Before that happens, keep the deflection voltage and the lowest charging voltage constant and reduce the voltage between charging voltages. Have the means to go.

[0006]

When the character height is changed, by minimizing the change in the charging voltage, it is possible to reduce the difference in printing quality depending on the character height. In addition, decrease the deflection voltage,
Before the lowest charged ink particles collide with the unused ink particle recovery gutter, keep the deflection voltage and the lowest charged voltage constant,
Since there is a means of reducing the voltage between charging voltages, it is possible to print even sufficiently small characters.

[0007]

1 is a block diagram of a character height control device for an ink jet printer according to the present invention. The microprocessor (MPU) 1 is a main circuit element that controls the overall control of the inkjet printer, and the ROM 2 is a read-only memory that stores programs and control data necessary for the MPU 1 to operate. . RA
M3 is a rewritable memory that temporarily stores data and the like handled by the MPU while the program is being executed. The bus line 4 is a signal line for transmitting a data signal, an address signal and a control signal of the MPU 1.

A first-in first-out register (FIFO) 5 stores dot data of a character pattern output from the MPU 1 in 1-byte units. FIFO
The output of 5 is led to the selector (C) 8. Selector (C)
Reference numeral 8 sequentially converts 8-bit dot data output from the FIFO 5 in parallel and outputs the dot data, thereby converting the 8-bit dot data into a serial signal.

The peripheral interface adapter (PIA) 11 mediates input / output of various signals. The buffer (A) 12 is a data bus (D signal) in the MPU bus line 4 and a data bus (D) in the control RAM 13.
It has the function of connecting (signals) and specifying the direction of data flow. The control RAM 13 is the MPU1
Various control information necessary for sequentially executing the print control according to a predetermined procedure is stored. The selector (E) 14 is for switching the address information given to the control RAM 13.

The thinning switch 15 is for setting the utilization rate of ink particles continuously generated from the nozzles (allocation rate to matrix = thinning rate). The excitation setting switch 16 sets the frequency of the excitation signal applied to the nozzle 32 and specifies the generation period of the ink particles generated from the nozzle 32. The frequency division counter 17
The signal output from the oscillator 18 is used for the thinning switch 1
5, Divide based on the setting value of the excitation setting switch 16,
The count signal OT1 for obtaining the staircase wave data for generating the charging voltage, the thinning-out timing signal OT2, and the excitation signal OT3 for exciting the nozzle 32 are generated.

The column counter 6 repeatedly operates at a cycle of a number including the number of print dots in the vertical direction and the number of idle dots for adjusting the character width. Total dot count is PIA11 PA
0 to PA7. The staircase wave counter 19 receives a clear signal for each column from the column counter 6 and then 0 to 1
Each dot printing is counted in ascending order. The output (OT1) of the counter is given to the selector (F) 22. The output signals of PB0 to PB2 of PIA11 are also selectors.
(F) It is given to 22. This signal specifies the format. The output of the selector (F) 22 is a video RA.
Given to M21. The buffer (B) 20 is a video RA
Used for data input / output of M21. This video RAM21
Stores the staircase wave according to the specified format, and also includes information on the character height. The shift register 24 outputs dot data (output ports QA, QB, QD, QE) corresponding to the ink particles in the charging control target column. The dot data corresponding to the front and rear ink particles is used for distortion correction. AND gate 29
Is an AND gate for generating a charging signal,
It is composed of 12 AND gate elements corresponding to each bit of the 12-bit digital signal given from M21,
Each AND gate element has one of the signals given from the video RAM 21, dot data outputted from the output port QC of the shift register (B) 24, and control R.
A column print area signal output from the AM 13 so as to specify the timing of printing one row of the matrix, PIA11
The print start signal output from the output port OT3 and the thinning-out timing signal output from the output port OT2 of the frequency division counter 17 are commonly input. The D / A converter 30 is for converting the digital charging signal output from the AND gate 29 into an analog signal, and the amplifier (AMP) 31 in the subsequent stage amplifies the output to obtain a charging voltage.

The nozzle 32 ejects the pressurized ink and gives a signal according to the excitation signal to the ink to specify the particle formation. The charging electrode 33 is arranged so as to surround the position where the ink ejected from the nozzle 32 is turned into particles, and the charging voltage is applied to charge the ink particles. With respect to the deflection voltage, its magnitude is determined by the signal output at the peripheral interface adapter (PIA) 34. The D / A converter 35 converts this deflection voltage signal into an analog signal, and the AMP 36 amplifies its output and applies it as a deflection voltage to the deflection electrode (+) 37. The deflection electrode (+) 37 and the deflection electrode (-) 38 form a deflection electric field in the ink particle flight path, and the ink particles 39 flying in the deflection electric field are deflected according to the charge amount.

The conveyor belt 44 carries a workpiece 42 to be printed by an ink jet printer and conveys the workpiece 42 at a predetermined constant speed in a direction perpendicular to the deflection direction of the ink particles 39. The gutter 40 is arranged in the flight path of the unused ink particles so as to capture and collect the unused ink particles not used for dot printing. The sensor 41 is the work 4 conveyed by the conveyor belt 44.
2 is detected, and is used to execute printing (charging) control in synchronization with the work 42 passing through the printing area facing the nozzle 32. The input panel 43 is used to set print contents (characters), specify the height and width of characters, and specify the type of matrix. This concludes the description of the configuration of the present invention, and then the character height control system of the present invention will be described. As a method of controlling the character height, there are a method of controlling a charging voltage and a method of controlling a deflection voltage. The present invention performs optimal correction by controlling both of these in good balance. FIG. 2 shows a change in charging voltage [A] and a change in deflection voltage [A] when printing with dot pattern 5 × 7, one-step printing, and a printing example [C] when printing with that voltage.
Is. The details of this method are as follows. When the character height is reduced to 300 to 150 by the panel input value, the charging voltage is first kept constant as shown in FIG.
Gradually reduce as shown in [a]. This voltage control is controlled by the 8-bit signal output from the PIA34 in FIG. During this period, the lowest charging voltage is about 90V and the highest charging voltage is about 240V. Further, the deflection voltage is about 5.7 kV at the maximum character height, which is set to a value such that there is no danger of dielectric breakdown due to the gap length between the deflection electrodes 37 and 38. As can be seen from the printed character results in FIG. 2C, the lowermost charged ink particles gradually approach the gutter level as the character height decreases in the area A. Therefore, the panel input value 150
However, this is the limit when lowering the deflection voltage. If the deflection voltage is continued to be lowered in order to further reduce the character height from here, the lowest charged ink particles collide with the unused ink particle recovery gutter 40 in the middle thereof. The deflection voltage value at that time is
It is about 2.8 kV with a standard machine with a 65 μm nozzle diameter, but it is kept constant at a deflection voltage of about 3.0 kV just before that so that the lowest charged ink particles do not collide with the unused ink particle recovery gutter 40. . The character height panel input values 150 to 0, which is the area B in FIG. 2A, are performed by keeping the deflection voltage and the lowest charging voltage 90V constant and reducing the voltage between charging voltages. At this time, PIA3
The deflection voltage of the output signal 4 is kept constant at 3.0 kV and is controlled by the staircase wave charging signal output from the video RAM 21. Further, the charging voltage waveform when the character height is changed is shown in FIG. 3. In FIG. 3, the lowest charging voltage is always constant regardless of the size of the character, and the character height is When it is large, the uppermost charging voltage of the staircase waveform of the charging voltage and the voltage between charging voltages are increased as shown in (a). When the character height is small, the staircase waveform of the charging voltage of Character height is controlled by reducing the highest charging voltage and the voltage between charging voltages.

[0014]

According to the present invention, when the character height is changed, the change of the charging voltage is minimized by changing the deflection voltage. Therefore, the print character height is not affected and the printing quality is always good. There is an effect that can be obtained.

Further, even if the deflection voltage becomes small, the lowest charging ink particles cannot be sufficiently deflected, and the lowest charging voltage and the deflection voltage are kept constant before they collide with the unused ink particle collecting gutter. Since there is a means to reduce the size, there is an effect that even small characters can be printed.

[Brief description of drawings]

FIG. 1 is a block diagram of an inkjet printer according to the present invention.

FIG. 2 is a diagram showing an example of a control method of the character height control device according to the present invention, showing how the charging voltage and the deflection voltage change, and an example of a printed character result.

FIG. 3 is an example of a control method of the character height control device according to the present invention, and is a staircase waveform diagram of the charging voltage when the character height is changed.

[Explanation of symbols]

1 ... Microprocessor, 6 ... Column counter, 13 ... Control RAM, 19 ... Staircase wave counter, 21 ... Video RAM.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location 9012-2C B41J 3/04 104 G

Claims (2)

[Claims] 1. A pressurizing ink is ejected from a nozzle, and the nozzle is vibrated at a constant cycle so that the ink is made into particles at a constant cycle. When printing is performed in an inkjet printer that forms characters on an object to be printed by causing the charged particles to fly in a deflection electric field to vertically deflect and relatively move the object to be printed at a right angle to the vertical deflection of the ink particles. In addition, the character height control device for an ink jet printer is characterized in that the character height to be printed is controlled by combining and changing the charging voltage and the deflection voltage. 2. The deflection according to claim 1, wherein when the character height is made smaller than the maximum character height, the ink particles charged at the lowest voltage of the staircase charging voltage can jump over the unused ink particle collecting gutter. In the range of deflection voltage that can take a large amount, the deflection voltage is not changed and only the deflection voltage is lowered.If the deflection voltage is further lowered, the lowest charged ink particles will collide with the unused ink particle recovery gutter. A character height control device for an ink jet printer, characterized in that the deflection voltage and the lowest voltage are kept constant, and then the voltage between charging voltages is reduced to reduce the character height.