JP2012066489A - Method of computing duration of bst waveform - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of computing the duration of a BST waveform without using a special device.SOLUTION: First driving signals having different AL values are input to an inkjet head to compute the AL values for minimizing the quantity of ink to be discharge, from the result of measuring the mass of a recording medium for each of the first driving signals. In second driving signals having one driving waveform of the AL value and the BST waveform in a predetermined driving period, the mass of the recording medium is measured for each of the second driving signals having different durations of the BST waveform. In third driving signals having two driving waveforms of the AL value and the BST waveform, the mass of the recording medium is measured for each of the third driving signals having different durations of the BST waveform. The duration of the BST waveform is computed so that the quantity of ink to be discharged using the BST waveform and a first driving waveform and the quantity of ink to be discharged using a second driving waveform are equal to each other, on the basis of the results of the measurements.

Description

  The present invention relates to a method for calculating a time width of a BST waveform.

A drive signal in which the number of drive waveforms corresponding to the target gradation is inserted within a predetermined drive cycle is input, and ink is ejected a number of times according to the number of drive waveforms within the predetermined drive cycle (for example, the target gradation is There is known a multi-drop driving type ink jet head that forms dots of a target gradation by performing 7 drops in the case of 8 gradations (for example, Patent Document 1). In this type of ink jet head, the discharge amount of the first drop ink is generally smaller than the discharge amount after the second drop. Therefore, in order to increase the discharge amount of the first drop, a so-called BST (Boost) waveform is inserted before the drive waveform of the first drop.
Conventionally, the time width of a BST waveform is calculated by observing ink ejected from an inkjet head using a special device such as a flying droplet observation device.

  However, the conventional method of calculating the time width of the BST waveform using a special device such as a flying droplet observation device cannot calculate the time width of the BST waveform when the inkjet head is incorporated in the printer. There is a problem that a special device such as a flying droplet observation device is required to calculate the time width.

  The present invention provides a time width calculation method for a BST waveform that can calculate the time width of a BST waveform with an inkjet head incorporated in an image forming apparatus, and that can calculate the time width of a BST waveform without using a special device. The purpose is to do.

  In order to solve the above-described problem, according to one aspect of the present invention, each first drive signal having a different AL value in a first drive signal in which a plurality of drive waveforms are inserted within a predetermined drive cycle is input to the inkjet head. Printing on the recording medium, measuring the mass of the recording medium for each of the first drive signals, calculating the AL value that minimizes the ink ejection amount from the measurement result, and within the predetermined drive cycle In a second drive signal having one drive waveform of the AL value and a BST waveform inserted before the drive waveform, each second drive signal having a different time width of the BST waveform is input to the inkjet head. Printing on the recording medium, measuring the mass of the recording medium for each of the second drive signals, and before the two drive waveforms, the two drive waveforms of the AL value within the predetermined drive cycle. BST waveform inserted in In each of the third drive signals, the third drive signals having different time widths of the BST waveform are input to the inkjet head to perform printing on the recording medium, and the recording medium for each third drive signal , And based on the measurement results of the second and third drive signals, the ink discharge amount by the BST waveform and the first drive waveform and the ink discharge by the second drive waveform The present invention relates to a BST waveform time width calculation method for calculating a time width of a BST waveform having the same amount.

  As described in detail above, according to the present invention, the time width of the BST waveform can be calculated with the inkjet head incorporated in the image forming apparatus, and the time width of the BST waveform can be calculated without using a special device. It is possible to provide a BST waveform time width calculation method that can be used.

It is a block diagram which shows PC of this embodiment. It is a flowchart for demonstrating the time width calculation method of a BST waveform. It is a figure which shows a 1st drive signal. It is a figure which shows UL value from which the discharge amount of ink becomes the minimum. It is a figure which shows a 2nd drive signal. It is a figure which shows the discharge amount of the ink at the time of a 2nd, 3rd drive signal being input. It is a figure which shows a 3rd drive signal.

Hereinafter, embodiments will be described with reference to the drawings.
FIG. 1 is a block diagram showing a PC 1 (Personal Computer) of this embodiment.
The PC 1 includes a processor 11, a memory 12, an ASIC 13, an HDD 14, a display unit 15, and an operation unit 16.
The processor 11 performs various processes in the PC 1 and implements various functions by executing programs stored in the memory 12.
The memory 12 may be, for example, a RAM (Random Access Memory), a ROM (Read Only Memory), a DRAM (Dynamic Random Access Memory), an SRAM (Static Random Access Memory), or a VRAM (Video RAM). Store various information and programs.

The display unit 15 displays various operation screens and measurement results. The display unit 15 may be an LCD (Liquid Crystal Display), an EL (Electronic Luminescence), a PDP (Plasma Display Panel), or a CRT (Cathode Ray Tube).
The operation unit 16 may be a keyboard, a mouse, a touch panel, a touch pad, a pen tablet, a dedicated button, or the like. The display unit 15 and the operation unit 16 are configured as a single unit, and may be a touch panel display device.
An image forming apparatus 2 and a mass meter 3 are connected to the PC 1. The PC 1 outputs a drive signal to the image forming apparatus 2 and controls the image forming apparatus 2. The PC 1 controls the mass meter 3.

The image forming apparatus 2 may be a printer, for example, and forms an image by ejecting ink onto a recording medium S such as paper. The image forming apparatus 2 includes an inkjet head 21.
The inkjet head 21 may eject one of color inks such as yellow, magenta, cyan, black, and white ink. The ink jet head 21 includes a piezoelectric member that deforms according to a drive waveform in a drive signal input to the ink jet head 21, an ink chamber whose volume changes due to the deformation of the piezoelectric member, and an ink when the volume of the ink chamber decreases. And a nozzle for discharging the ink to the outside of the inkjet head 21. When the drive waveform is a positive voltage, for example, the inkjet head 21 discharges ink by reducing the volume of the ink chamber by the piezoelectric member. The inkjet head 21 is driven by a multi-drop driving method, and ejects ink at a number of times corresponding to the number of drive waveforms inserted within a predetermined drive cycle in an input drive signal, thereby forming a target gradation dot. Form.

  The mass meter 3 measures the mass of the recording medium S on which the ink has been ejected, and outputs the measurement result to the PC 1.

  Hereinafter, a method for calculating the time width of the BST waveform of the present embodiment by the PC 1 will be described. FIG. 2 is a flowchart for explaining a method for calculating a time width of a BST waveform, FIG. 3 is a diagram showing a first drive signal, and FIG. 4 is a diagram showing a UL value at which the ink ejection amount is minimized.

  First, in the first drive signal in which seven drive waveforms are inserted within a predetermined drive cycle T as shown in FIG. 3, the PC 1 has a UL value (also referred to as a (Unit Length) value or an AL (Acoustic Length) value). The first drive signals (voltage Vaa constant, no BST waveform) having different values are input to the inkjet head 21 to perform printing on the recording medium S, and the mass of the recording medium S for each first drive signal is mass. Measure by total 3. Note that each time the inkjet head 21 prints on the recording medium S, the operator may transfer the recording medium S to the mass meter 3, or the same operation may be automatically performed by an appropriate machine. The inkjet head 21 has, for example, 318 nozzles and is driven at a drive frequency of 4.8 KHz. The fact that the operator may transfer the recording medium S to the mass meter 3 and that the inkjet head 21 is driven at a drive frequency of 4.8 kHz, for example, are the same in ACTs 2 and 3 described later. The PC 1 subtracts the mass of the recording medium S before ink adhesion from the mass of the recording medium S measured for each first drive signal with a different UL value, and varies the UL value as shown in FIG. The ink ejection amount for each first drive signal is calculated, and the UL value that minimizes the ink ejection amount is calculated. In the present embodiment, the PC 1 calculates the UL value that minimizes the ink ejection amount as 2.50 μs (ACT1).

  After the ACT1, the PC1 includes a drive waveform P having a UL value (2.50 μs) calculated by the ACT1 and a BST waveform inserted before the drive waveform within a predetermined drive cycle T. In the signal (FIG. 5), each second drive signal with a different time width tb of the BST waveform is input to the inkjet head 21 to print on the recording medium S. Then, the PC 1 measures the mass of the recording medium S for each second drive signal by the mass meter 3 and calculates the ink ejection amount for each second drive signal (see 1 drop in FIG. 6, ACT 2).

  After ACT2, PC1 includes two drive waveforms P having a UL value (2.50 μs) calculated by ACT1 and a BST waveform inserted before the two drive waveforms within a predetermined drive cycle T. In the two drive signals (FIG. 7), each second drive signal with a different time width tb of the BST waveform is input to the inkjet head 21 to print on the recording medium S. Then, the PC 1 measures the mass of the recording medium S for each second drive signal by the mass meter 3, and calculates the ink ejection amount for each second drive signal (see 2drop in FIG. 6, ACT3). Note that the order of ACT2 and ACT3 may be changed.

After ACT 3, the PC 1 determines the ink discharge amount based on the BST waveform and the first drive waveform and the ink discharge amount based on the second drive waveform based on the measurement results based on the second and third drive signals. A time width tb of equal BST waveforms is calculated. In the present embodiment, the PC 1 calculates the time width tb of the BST waveform as 0.72 μs as shown by the broken line in FIG. 6 (ACT 4).
Each operation in the processing in the PC 1 described above is realized by causing the processor 11 to execute a BST waveform time width calculation program stored in the memory 12.

In the present embodiment described above, since the time width tb of the BST waveform can be calculated in a state where the inkjet head 21 is incorporated in the image forming apparatus 2, the drive waveform can be optimized in accordance with changes in the operating temperature environment.
In the present embodiment, the drive waveform of the ink jet head 21 can be determined by a generally available mass meter 3 without using a special device such as a flying droplet observation device.

  In the above embodiment, seven drive waveforms are inserted in the first drive signal, but an appropriate number may be inserted.

  The present invention can be implemented in various other forms without departing from the spirit or main features thereof. Therefore, the above-described embodiment is merely an example in all respects and should not be interpreted in a limited manner. The scope of the present invention is indicated by the scope of claims, and is not restricted by the text of the specification. Further, all modifications, various improvements, alternatives and modifications belonging to the equivalent scope of the claims are all within the scope of the present invention.

  21 Inkjet head, S recording medium.

JP 2006-137047 A

Claims (2)

Each first drive signal having a different AL value in a first drive signal in which a plurality of drive waveforms are inserted within a predetermined drive cycle is input to the ink jet head to perform printing on a recording medium. Measure the mass of the recording medium for each drive signal and calculate the AL value that minimizes the ink ejection amount from the measurement result.
In the second drive signal including one drive waveform of the AL value and a BST waveform inserted before the drive waveform within the predetermined drive cycle, each second drive having a different time width of the BST waveform. A signal is input to the inkjet head to perform printing on a recording medium, and the mass of the recording medium for each second drive signal is measured,
In a third drive signal comprising two drive waveforms of the AL value within the predetermined drive cycle and a BST waveform inserted before the two drive waveforms, each time width of the BST waveform is made different. 3 driving signals are input to the inkjet head to perform printing on a recording medium, and the mass of the recording medium for each third driving signal is measured,
Based on the measurement result of the second and third drive signals, the BST waveform and the first drive waveform ink discharge amount are equal to the ink discharge amount of the second drive waveform. A method for calculating a time width of a BST waveform. In the BST waveform time width calculation method according to claim 1,
The mass of the recording medium is a time width calculation method of a BST waveform measured by a mass meter.

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