JPH04357036A - Ink jet printer - Google Patents

Abstract

PURPOSE:To obtain the flying speed and size of ink droplets in the same state as in the case of the single drive of a nozzle by summing the total weights for other nozzles to be driven simultaneously with an arbitrary nozzle and varying the driving pulse width for the arbitrary nozzle in accordance with the total weight. CONSTITUTION:Image data for 48 lines are transferred from an image memory 3 to a line buffer 5, and, according to the image data, the pulse width of a driving pulse to be applied to a piezoelectric transducer for each of nozzles is determined by a pulse width modulation unit 6. The driving pulse width for an arbitrary nozzle is determined in such a manner that the weight for each of all other nozzles to be driven at the same timing as that of the arbitrary nozzle is determined according to a table on the basis of respective distances from the artitrary nozzle and then the total weight is summed to determine the driving pulse width according to another table. An operation driver means 7 generates a driving pulse that meets pulse width thus determined. By applying this driving pulse to a piezoelectric transducer for a printing head 8, ink droplets having optimum sizes and optimum flying speed can be obtained in the same state as in the case of the single drive of one nozzle.

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 apparatus, and more particularly to a method for generating drive pulses for ejecting ink from a print head.

0002

[Prior Art] Conventional inkjet printers have been designed to reduce the problems that occur when piezoelectric transducers of multiple nozzles are driven simultaneously, such as the influence of fluid vibration from adjacent nozzles and insufficient ink supply. The ink flow path that supplies ink to the nozzle is made longer or has a more complicated shape.

0003

[Problems to be Solved by the Invention] In the conventional inkjet printer described above, even if the ink channels in the print head are made long or complicated, ink is supplied from the same ink reservoir through each ink channel. When the piezoelectric transducers of multiple nozzles are driven at the same time, it is not possible to completely eliminate the effects of ink fluid vibration and ink supply shortages, and the size and flying speed of ink droplets are smaller than when they are driven individually. The problem was that it was small. In particular, this phenomenon becomes more pronounced as the nozzles that are driven simultaneously are closer together.

Accordingly, an object of the present invention is to obtain the same flying speed and size of ink droplets even when the piezoelectric transducers of a plurality of nozzles are driven at the same time as when they are driven individually.

[0005]

[Means for Solving the Problems] In order to achieve the above object, in the inkjet printer of the present invention, each of the other nozzles is weighted according to the distance from the other nozzle to the arbitrary nozzle. The weights for this nozzle and other nozzles driven simultaneously are summed, and the pulse width of the drive pulse applied to the piezoelectric transducer of the arbitrary nozzle is changed in accordance with the weight.

Note that the weight may be constant regardless of the distance between any nozzle and another nozzle.

[0007] It is also possible to check all the nozzles in the head that are driven simultaneously and determine the pulse width of the drive pulse for any nozzle, or you can check the investigation range of the nozzles that are driven simultaneously It is also possible to limit the number of nozzles on the left and right of the user.

Furthermore, in order to make the timing at which ink is ejected the same for all nozzles, it is preferable to synchronize with the falling edge of the drive pulse.

[0009]

[Operation] The ink droplets ejected from the inkjet printer configured as above are set with the drive pulse width and drive voltage based on the setting standard when one nozzle is driven alone, so that the ink droplets have the optimal size and flying speed. It is possible to obtain the same size and flight speed as the ink droplets. In other words,
When driving multiple nozzles at the same timing, the more nozzles that are driven at the same time, the more the ink supply shortage to the nozzles increases. By changing the number of ink droplets, it is possible to compensate for insufficient supply of ink to the nozzles, and ink droplets with the optimum size and flight speed can be obtained as in the case of driving one nozzle alone.

Furthermore, since the timing at which ink droplets fly out from the orifice at the tip of the head is caused by the falling edge of the driving pulse, by making the falling edge of the driving pulse common to all nozzles, the accuracy of ink droplet landing on paper can be improved. The decline can be prevented.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained below with reference to the drawings. In FIG. 2, the input section 1 is connected to the control section 2 inside the printer.
The print data taken in is subjected to image processing in the image processing section 4 and stored in the image memory 3. During printing, 48 lines of image data are transferred from the image memory 3 to the line buffer 5, and the pulse width of the drive pulse applied to the piezoelectric transducer of each nozzle is determined by the pulse width modulation section 6 based on the image data. . The drive driver 7 generates a drive pulse that matches the determined pulse width. By applying this to the piezoelectric transducer of the print head 8,
Ink droplets fly out from the nozzle and printing is performed.

In the embodiment shown in FIG. 1, weights are determined as shown in Table 1 depending on the distance between the driven nozzle and other nozzles.

[0013]

[Table 1]

The distance 1 here indicates the distance between adjacent nozzles. For example, the distance between the first nozzle and the fifth nozzle is four. Furthermore, ten types of pulse widths of the driving pulses, from the basic waveform to waveform 9 shown in FIG. 3, are used. Therefore, the drive pulse width of an arbitrary nozzle can be determined by calculating the weights in Table 1 from the distances to the arbitrary nozzle for all other nozzles that are driven at the same timing as that nozzle, and then summing these weights. It was determined using Table 2.

[0015]

[Table 2]

For example, let us find the drive pulse for the second dot of the sixth nozzle in FIG. First, the nozzles that are driven simultaneously with the 6th nozzle are the 3rd, 7th, 8th, 9th, 10th, 13th, and 17th nozzles.
Therefore, it is unknown after the 18th nozzle. However, as shown in Table 1, when the distance between nozzles is 6 or more, the weight is 0, so the nozzles involved in determining the pulse width are the 3rd and 7th nozzles.
, 8, 9, and 10 nozzles. Next, when calculating the weight from the distance between these nozzles and the 6th nozzle, the weight for the 3rd nozzle is 4,
The 7th nozzle is 16, the 8th nozzle is 8, the 9th nozzle is 4,
Since the 10th nozzle is 2, the total weight of this is 34
become. As a result, the drive pulse for the sixth nozzle becomes waveform 5 from Table 2. This method is applied to all nozzles.

In the embodiment shown in FIG. 5, the search for nozzles that are driven at the same time for arbitrary nozzles is performed using a distance of up to 2 between nozzles as shown in Table 3.

[0018]

[Table 3]

Furthermore, since the weight is set to 1, the total weight becomes 0 to 4 as shown in Table 4, and drive waveforms with five types of pulse widths shown in FIG. 4 are used depending on each of the totals. .

[0020]

[Table 4]

[0021] By doing so, calculations for determining the pulse width of the drive pulse are facilitated.

Note that for any nozzle, the search range of nozzles driven at the same timing is the sum of n nozzles on the left side and m nozzles on the right side of the arbitrary nozzle.
It may be a range of . Furthermore, the ranges of n and m may be made variable for each nozzle.

[0023]

As explained above, according to the present invention, it is possible to reduce the flying speed of ink droplets and reduce the size of ink droplets caused by insufficient ink supply due to simultaneous driving of multiple nozzles. This can be easily prevented without changing the shape of the ink flow path within the printer, and the print head can be made smaller. Furthermore, by giving more weight to the distance between the nozzles, it is possible to more effectively suppress the influence of other nozzles that are driven simultaneously on a given nozzle.

Furthermore, by limiting the search range for other nozzles that are driven simultaneously with respect to any nozzle, calculations for determining the pulse width can be simplified. Furthermore, it can be flexibly adapted to the shape of the ink flow path of the print head. Furthermore, by making the falling timing of the drive pulse constant for all nozzles, it is possible to synchronize ink ejection, and it is possible to prevent a decrease in printing accuracy caused by increasing the pulse width.

[Brief explanation of the drawing]

FIG. 1 is a time chart showing an embodiment of an inkjet printer of the present invention.

FIG. 2 is a control block diagram of the embodiment of FIG. 1;

FIG. 3 is a drive waveform used in the embodiment of FIG. 1;

FIG. 4 is a drive waveform used in another example.

FIG. 5 is a time chart of another embodiment.

[Explanation of symbols]

1 is an input section, 2 is a control section, 3 is an image memory, 4 is an image processing section, 5 is a line buffer, 6 is a pulse width modulation section,
7 is a drive driver, and 8 is a print head.

Claims (3)

[Claims] 1. A nozzle forming part having a plurality of nozzle openings, a piezoelectric transducer, and a heating means, the heating means heat and liquefy solid ink at room temperature, and the ink filled in the nozzle forming part is transferred to the piezoelectric transducer. In an inkjet printer that ejects and prints, any nozzle can
Weights are given according to the distances from other nozzles, the weights of other nozzles driven at the same time as the arbitrary nozzle are summed, and the pulse width of the driving pulse applied is changed according to the size. An inkjet printer characterized by: 2. The inkjet printer according to claim 1, wherein the weight of the nozzle is constant regardless of the distance between any nozzle and another nozzle. 3. The inkjet printer according to claim 1, wherein all of the drive pulses applied to the piezoelectric transducer have the same fall timing.