KR100727966B1 - Method for controlling driving pulse of head in ink jet printer - Google Patents

Abstract

A drive pulse control apparatus for a bubble jet head for generating bubbles by electro-thermal conversion means and discharging ink. The present invention relates to a head drive control method of an inkjet printer, comprising: counting the number of ink droplets simultaneously ejected from each ejection element of the head, measuring a temperature generated from a substrate of the head, and counting each ejection element from the count result Estimating the instantaneous temperature of the sensor; determining a correction value of the head drive waveform from the measured substrate temperature and the estimated instantaneous temperature; and adjusting a driving pulse width of the head based on the determined correction value. .

Description

{Method for controlling driving pulse of head in ink jet printer}

1 is a flowchart showing a drive control method of a conventional inkjet printer head.

2 is an embodiment of a drive control apparatus for an ink jet head according to the present invention.

3A and 3B are explanatory diagrams of operations in the first embodiment of FIG.

4A to 4C are explanatory diagrams of operations in the second embodiment of FIG.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet printing apparatus for ejecting ink droplets and to printing, and more particularly, to a method of controlling a pulse of a bubble jet head for generating bubbles by electro-thermal conversion means to eject ink.

Typically, printing devices such as copiers and printers are adapted to print an image composed of a dot pattern on a printing medium such as a paper sheet or a plastic plate based on the image information. Such printing apparatuses are classified into inkjet systems, wire dot systems, temperature systems, and laser beam systems based on the type of printing system. An inkjet system (inkjet printing apparatus) prints an image by discharging ink droplets from a discharge hole in a print header to deposit ink droplets on a print medium.

A technique related to ink head drive control of such an ink jet printing apparatus is disclosed in US Pat. No. 6,873,713 (filed 28 Jul. 2000 entitled PRINTING APPARATUS, CONTROL METHOD OF THE APPARATUS, AND COMPUTER-READABLE MEMORY).

Referring to FIG. 1, a technique related to the conventional ink head drive control detects a heater rank TrON rank and an ambient temperature provided by printhead characteristics (S101). Next, the driving pulse No is determined based on the heater rank TrON rank and the ambient temperature (S102). Next, the basic pulse width corresponding to the drive pulse No is determined (S103). Subsequently, the number of simultaneous ink discharge nozzles of the printhead to be processed is determined (S104). Subsequently, the modulation amount of the basic pulse width corresponding to the number of simultaneous ink discharge nozzles is determined (S105).

Therefore, in the prior art as shown in FIG. 1, in order to prevent a phenomenon in which driving energy decreases due to a voltage drop when driving a plurality of heaters at the same time, a printhead state may be adjusted by adjusting a driving pulse width according to the number of heaters simultaneously discharged. When the driving signal number is determined by TrON rank, temperature rank, etc., the pulse width is determined. The drive signal is obtained by applying a correction value according to the number of drive elements discharged simultaneously to this reference pulse.

However, in general, the bubble-jet head characteristics have a complicated influence on driving conditions and head temperature. Since the above-described prior art cannot correct the instantaneous temperature change of each nozzle, the ejection state of the ink is not constant for each nozzle and the print quality is deteriorated. In addition, when driving a nozzle with a high temperature and a low nozzle under the same drive conditions, since a ink viscosity falls with a nozzle with a high temperature, an ink drop rate will rise and the weight of an ink drop will fall. Therefore, as a result of printing, there is a problem that the line width is thinned and the accuracy of dot position is lowered.

The technical problem to be solved by the present invention is to correct the driving waveform of the head by predicting the influence of voltage drop and thermal accumulation and the instantaneous temperature change of each nozzle by the number of nozzles discharged at the same time to solve the driving voltage and thermal problems simultaneously. The present invention provides a method of controlling a driving pulse of a bubble jet head.

In order to solve the above first technical problem, a head drive control method of an inkjet printer of the present invention, the method comprising: counting the number of ink droplets ejected simultaneously from each ejection element of the head; Measuring a temperature occurring at the substrate of the head; Estimating the instantaneous temperature of each discharge element from the count result; Determining a correction value of the head drive waveform from the measured substrate temperature and the estimated instantaneous temperature; And adjusting the driving pulse width of the head based on the determined correction value.

delete

delete

delete

delete

delete

In order to solve the above second technical problem, in the head drive control method of the inkjet printer of the present invention, each head chip is divided into a plurality of parts, and the total number of times that the ejection element is driven within a predetermined time for each part is determined. Counting process; Measuring a substrate temperature of the head; Estimating a partial temperature of each region from the measured substrate temperature and the count result; Determining a correction value of the head drive waveform from the partially estimated temperature of each of the measured areas; And adjusting the driving pulse width of the head based on the determined correction value.

delete

delete

delete

delete

delete

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

The bubble jet head, which generates bubbles by using a conventional electro-thermal conversion element to eject ink droplets, divides the entire ejection element into a plurality of blocks, and ejects ink droplets by dividing the ejection droplets into several blocks one by one. That is, if the total number of ejection elements is T and the maximum number of ejection elements for ejecting ink droplets is m, one frame period is divided into T / m to drive the entire ejection elements.

Here, when a plurality of discharge elements are driven at the same time, a phenomenon occurs in which the driving power is lowered due to the internal resistance of the driving circuit or the capacity of the power supply. In addition to this phenomenon, when the same ejection element is continuously driven, the viscosity of the ink decreases due to heat accumulation, and the ejection characteristics change. Normally, this temperature change is detected by a temperature sensor provided on the substrate of the head to correct the drive waveform, but it is difficult to detect the temperature of each ejection element, and moreover, to respond to the instantaneous temperature change after ejecting ink droplets. There was no way.

2 is an embodiment of a drive control apparatus for an ink jet head according to the present invention.

The drive control apparatus of the inkjet head of FIG. 2 includes a data processor 210, a discharge water counter 220, a drive waveform controller 230, a temperature converter 240, a temperature sensor unit 250, and a drive waveform generator ( 260, a discharge element portion 270.

The driving control apparatus of the inkjet head of FIG. 2 will be described by dividing into a first embodiment and a second embodiment.

Referring to the first embodiment, the data processing unit 210 converts image data into print data, for example, a plurality of bits of images are converted into one bit of printing dots. Is discharged to the discharge water counter 220. The discharge water counter 220 is a simultaneous discharge water counter (not shown) for counting dots discharged at the same time and for each nozzle for each nozzle counting the number of dots discharged within a predetermined period. A discharge water counter (not shown) is provided, and these count results are transmitted to the drive waveform control unit 230. At the same time, the temperature sensor 250 is provided on the substrate of the head chip to determine the temperature of the heater in the head. The temperature converter 240 converts the temperature level detected by the temperature sensor 250 into temperature data and transmits the temperature to the driving waveform controller 230.

The drive waveform control unit 230 determines a correction value of a drive signal for driving each discharge element based on the count value of the discharge water counter 220 and the temperature data of the temperature converter 240, and together with the print data, the drive waveform generator. Send to 260.

The drive waveform generator 260 generates a drive waveform for driving each discharge element 270 from this input to drive each discharge element 270. Here, the ejection element 270 means one cell composed of at least one nozzle opening, a heater for generating a pressure for ejecting ink droplets from the nozzle opening, and an ink oil for guiding ink in the nozzle opening.

The reason why the driving waveform is adjusted by the number of dots discharged at the same time is to prevent the power applied to the above-described heater from dropping when the number of dots discharged at the same time is large due to the internal resistance of the head and the power of the power source.

Further, the drive waveform control unit 230 determines the instantaneous temperature at the time of starting the ink ejection operation of each dot of each drive element from the counter result of the ejection water counter 220 for each nozzle and the detection result by the temperature sensor 250. Estimate. For example, when the count result is s and the detection result of the temperature sensor is Tb, the drive pulse width Tw is represented by Tw = T0 + (Tb + (a x s)) b. Where a and b are predetermined integers and T0 is a basic pulse width.

A second embodiment will be described with reference to FIG.

The data processing unit 210 converts image data into print data. The discharge water counter 220 divides each head chip into a plurality of parts by counting the simultaneous discharge water counter (not shown) for counting dots discharged at the same time, and counting the total number of dots discharged within a predetermined time for each part. Section discharge water count (not shown). In the second embodiment, the head is divided into a plurality of parts to estimate the instantaneous temperature at the time of starting the ink ejection operation by the same method as in the first embodiment. That is, when the counter result of the interval discharge water counter is t and the detection result of the temperature sensor 250 is Tb, the driving pulse width Tw is expressed as Tw = T0 + (Tb + (cxt) d, where c, d Is a predetermined integer, T0 is the basic pulse width.

3A and 3B are explanatory diagrams of operations in the first embodiment of the present invention.

Referring to FIG. 3A, ink droplets are ejected from the inkjet head 10 from a plurality of ejection elements. The number of ink droplets 11 discharged between the predetermined ranges L immediately before the ink droplets 12 are discharged is counted for each discharge element. Here, d1 to dm are discharge elements driven simultaneously, and the counted result is referred to as n to nm. The actual discharge number s at each position in the scanning direction is determined by the printing pattern. In the discharge of the ink droplets 12, the basic drive waveform Pw is first determined by the actual discharge water s. Here, the larger the pulse width is, the larger the actual discharge water s is. Next, the instantaneous temperature of each discharge element is estimated from the detected temperature tb by the temperature sensor and the count results n1 to nm described above. This method can be realized by, for example, preparing a conversion table of temperature rise by the magnitude of the count result n1 to nm and adding the value and tb.

Next, the correction value Ph of the drive waveform is determined from the instantaneous temperature of each drive element. Even in this case, the correction value can be easily obtained from the temperature using a conversion table or conversion equation of the correction value. The correction value Ph may be represented by the ratio or may be represented by the width of the adjustment. The driving pulse width Pwh is obtained for each driving element. Pwh becomes Pw * Ph or Pw + Ph.

In this way, dn is driven from d1 by the drive means based on the requested drive pulse width Pwh. 3B shows the driving waveform. In the range L, since the number of discharges is large in the order of d2, dm, and d1, the pulse width is shortened in this order (the amount of correction increases). In the case of correction, it is preferable to adjust the start timing of driving to make the end position the same. The reason for this is that the discharge is quicker as the temperature is higher, so that the alignment accuracy of the dots can be improved by matching the end position of driving.

Further, by applying this configuration further, by referring to the count results of the ejection elements on both sides of the ejection element for adjusting the pulse width, high accuracy correction is possible. The influence of the discharge elements on both sides in that case is estimated from several tens to about several percent.

4A to 4C are diagrams illustrating the operation of the second embodiment of the present invention.

4A, first, the head is divided into a plurality of parts. This split is to estimate the temperature of the part.

Ink droplets are ejected from the plurality of ejection elements from the ink jet head 10, and the number of ejected droplets 11 between a certain range L immediately before the ejection of the droplets 12 is discharged from a1 to am. Count each area. The counted result is called nm from n1. Here again, the actual discharge water s at each position in the scan direction is determined by the print pattern.

In the discharge of the ink droplets 12, the basic drive waveform Pw is determined by the size of the actual discharge water s so that the pulse width becomes longer as the actual discharge water s is larger. Next, the partial temperature in each area | region is estimated from the detection temperature tb by a temperature sensor and the count result n1-nm mentioned above. A partial temperature estimation method of each region will be described with reference to FIG. 4B. That is, the temperature difference of each area | region is estimated by the conversion table of temperature rise etc. based on the count result n1-nm first. The temperature of the region (nm in FIG. 4B) closest to the temperature sensor is regarded as the temperature detected by the temperature sensor, and the temperature of each region is estimated by adding the temperature difference for each region.

Next, the correction value Ph of the drive waveform is determined from the partial temperature of each region. Even in this case, the correction value can be easily obtained from the temperature using a conversion table or conversion equation of the correction value. The correction value Ph may be represented by the ratio or may be represented by the width of the adjustment. The driving pulse width Pwh is obtained for each driving element. Pwh becomes Pw * Ph or Pw + Ph.

In this way, the ink droplets 12 are discharged by the driving means based on the required driving pulse width Pwh. At this time, the same driving waveform is applied to all the discharge elements in each region. The driving waveform is shown in Fig. 4C. Since the number of discharges is large in the order of a2, am, and a1 within the range L, the pulse width is shortened in this order (the amount of correction increases). In addition, when correcting, it is preferable to adjust the start timing of driving to make the end position the same. This reason is also the same as in the first embodiment.

In the above description, the first embodiment and the second embodiment have been described based on the number of discharge elements driven simultaneously. However, the main feature of the present invention is to estimate the instantaneous or partial temperature to correct the driving. It is in doing it. Therefore, when there is a margin in the drive circuit or the power supply, the basic drive waveform Pw may be a constant value regardless of the number of discharge elements driven simultaneously.

As described above, according to the present invention, it is possible to individually correct and control the change in characteristics due to the instantaneous temperature rise for each drive element, and to control the drive with high accuracy by estimating the temperature distribution in the head. . At the same time, it is possible to reduce excessive input energy to the discharge element.

Claims (5)

In the head drive control method of an inkjet printer, Counting the number of ink droplets ejected simultaneously from each ejection element of the head; Measuring a temperature occurring at the substrate of the head; Estimating the instantaneous temperature of each discharge element from the count result; Determining a correction value of the head drive waveform from the measured substrate temperature and the estimated instantaneous temperature; And adjusting the driving pulse width of the head based on the determined correction value. The method of claim 1, wherein the instantaneous temperature estimating step comprises preparing a conversion table of temperature rise by the magnitude of the count result, and adding the value and the substrate temperature. delete In the head drive control method of an inkjet printer, Dividing each head chip into a plurality of regions, and counting the total number of times the discharge element is driven within a predetermined time for each region; Measuring a substrate temperature of the head; Estimating a partial temperature of each region from the measured substrate temperature and the count result; Determining a correction value of the head drive waveform from the partially estimated temperature of each of the measured areas; And adjusting the driving pulse width of the head based on the determined correction value. 5. The method of claim 4, wherein the partial temperature estimation process of each region is based on the count result to estimate a temperature difference of each region by a conversion table of temperature rise, and calculates the temperature of the region of the position nearest to the temperature sensor. A method for controlling the head drive pulse of an inkjet printer, characterized in that it is regarded as a substrate temperature, and is estimated as a partial temperature of each region by adding the substrate temperature and the temperature difference of each region.

Images