JP2002234198A - Driving device for ink jet device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a driving device for an ink jet device that can execute a recording operation at high speed even when a driving waveform is long and can perform stable ejection even when dots for ejecting are continuous. SOLUTION: In the case where, for example, three ejection pulses are outputted with respect to one dot, when a dot in a printing cycle T starting from time t2 following a dot to be printed in a printing cycle T starting from time t1 is a printing cycle wherein the printing is not executed, a driving waveform H2 which is longer than a normal driving waveform H1 and bridges the two printing cycles T is used and the driving waveform H2 is outputted by being delayed by a delay time td from the normal driving waveform H1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of a driving device for an ink ejecting apparatus.

[0002]

2. Description of the Related Art An ink jet printer head in a piezoelectric ink jet printer is provided with a cavity having a pressure chamber and a piezoelectric element as an actuator provided adjacent to the pressure chamber of the cavity. By supplying a predetermined drive pulse to the piezoelectric element, the volume of the pressure chamber is reduced, and ink is ejected from the orifice. Further, by supplying a plurality of drive pulses for one dot, a dot having a desired density is formed.

For example, when two pulses are supplied as drive pulses, the second pulse is generated at a timing such that the residual pressure fluctuation in the pressure chamber caused by the first pulse becomes larger.
By supplying this pulse, the second ink droplet can be ejected efficiently.

However, when a plurality of pulses are supplied as described above, extra ink droplets called satellites may be generated when ink is ejected, in addition to the ink droplets that should be originally ejected. This is mainly due to the fact that after the ink is continuously ejected by a plurality of pulses, the pressure fluctuation in the cavity does not sufficiently fall even after the original ink droplet is ejected, and the ink is ejected due to the residual pressure. It is. When such satellites occur, the image quality of the formed characters and the like deteriorates.

Therefore, conventionally, a cancel pulse (stabilizing pulse) is added to a driving waveform in order to prevent the generation of the above-mentioned extra ink droplet. For example, when two pulses are supplied as described above, the second pulse
After the supply of the drive pulse, a method of supplying a cancel pulse at a timing that cancels out the residual pressure fluctuation in the pressure chamber is adopted. After the supply of the first drive pulse,
Similarly, a method of supplying a first cancel pulse for canceling the residual pressure fluctuation and supplying a second cancel pulse after the supply of the second drive pulse has been adopted.

[0006] The cancel pulse is particularly important when there is no ink ejection in the printing cycle of the next dot. That is, in the case where the ink ejection is also performed in the printing cycle of the next dot, the influence is small since the next ink ejection is performed again without sufficiently attenuating the residual pressure fluctuation. However, if there is no ink ejection in the printing cycle of the next dot, the above-mentioned satellite will occur unless the residual pressure fluctuation is sufficiently attenuated.

[0007] The determination as to whether or not ink is to be ejected for each printing cycle is made based on the dot information stored in the image memory. When a strobe as a reference for the operation of the ink jet head occurs, dot information is input as data to a control circuit of the ink jet head. Then, the control circuit determines a drive pulse corresponding to the dot information based on the dot information and a clock serving as a reference for generating the drive pulse.

[0008]

However, when a cancel pulse for sufficiently attenuating the residual pressure fluctuation is supplied as described above, the cancel pulse is inserted into the original drive pulse necessary for forming a dot. Therefore, the entire driving waveform becomes long.

As a result, the printing cycle must be determined in accordance with such a long driving waveform, and there is a problem that the operation speed of the ink jet head is reduced as a whole.

In the case where a plurality of drive pulses are supplied for one dot, for example, in the case where two printing cycles for ejection are continuous, depending on the number of pulses, the last drive pulse for the first dot may be changed depending on the number of pulses. The time until the first drive pulse for the next dot is shortened. as a result,
In some cases, the residual pressure in the pressure chamber was not sufficiently attenuated, and it was impossible to stably eject the next dot.

Therefore, the present invention solves such a problem, and enables the recording operation to be performed at a high speed even when the drive waveform is long, and even when the printing cycle for performing the discharge is continuous, the discharge is performed. It is an object of the present invention to provide a drive device for an ink ejecting apparatus that can be performed stably.

[0012]

According to a first aspect of the present invention, there is provided a driving apparatus for an ink ejecting apparatus, comprising: a cavity plate having a pressure chamber for discharging ink droplets; A driving device that outputs a driving pulse to the actuator at a predetermined printing cycle based on dot information to be sequentially formed along a direction of relative movement with a recording medium. When a plurality of the drive pulses are continuously output in order to form one dot with a plurality of ink droplets, the dot information of the current printing cycle is ejection, and the dot information of the next printing cycle is not ejected. In the case of ejection, the drive pulse is output with a predetermined time delay from the printing cycle.

According to the first aspect of the present invention, when a plurality of drive pulses are continuously output to form one dot by a plurality of ink droplets, the dot information of the current print cycle is output. When the ejection is performed and the dot information of the next printing cycle is non-ejection, the drive pulse is output with a predetermined time delay from the printing cycle. Therefore, even if a plurality of drive pulses are continuously output in a print cycle before the print cycle when the drive pulse is to be output, the output pulse is output from the last pulse of the output drive pulse. Since there is a time margin of a predetermined time longer than before until the first drive pulse of
The residual pressure in the pressure chamber due to the plurality of continuously output drive pulses is reliably attenuated, and the ejection of the ink by the plurality of continuously output drive pulses to be output from this is performed stably.

According to a second aspect of the present invention, there is provided a driving apparatus for an ink ejecting apparatus according to the first aspect of the present invention, wherein the driving is performed so that one dot is formed by a plurality of ink droplets. When a plurality of pulses are continuously output, if the dot information of the current printing cycle is ejection and the dot information of the next printing cycle is non-ejection, the driving is performed so as to straddle an adjacent printing cycle. It is characterized in that a plurality of pulses are continuously output.

According to the second aspect of the present invention, when a plurality of the drive pulses are continuously output so as to form one dot by a plurality of ink droplets, the dot information of the current printing cycle is output. Is the ejection, and when the dot information of the next printing cycle is non-ejection, the driving pulse is output not only by delaying the printing cycle by a predetermined time, but also over the adjacent printing cycle. A plurality of pulses are continuously output. Therefore, even if the drive pulse generated by the drive pulse output with a delay of the predetermined time is a long drive waveform, it is output in a short print cycle.

According to a third aspect of the present invention, there is provided a driving device for an ink ejecting apparatus according to the first or second aspect, wherein the plurality of driving pulses are continuously output. Includes a cancel pulse for reducing pressure fluctuations in the pressure chamber.

According to a third aspect of the present invention, the plurality of continuously output drive pulses include a cancel pulse for attenuating a pressure fluctuation in the pressure chamber. Therefore, even when a plurality of drive pulses are continuously output, the pressure fluctuation in the pressure chamber is stabilized. Further, when the dot information of the current printing cycle is ejection and the dot information of the next printing cycle is non-ejection, the driving pulse is output with a predetermined time delay from the printing cycle, so that the current printing is performed. Even if a drive pulse including the cancel pulse is output in a printing cycle earlier than the cycle, a sufficient time is provided for attenuating the pressure fluctuation in the pressure chamber, and the pressure fluctuation in the pressure chamber is surely reduced. Stabilization is achieved.

[0018]

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. The following description is an embodiment in which the present invention is applied to a piezoelectric inkjet head.

FIG. 1 is a schematic diagram showing an ink jet head 1 and a driving device 30 in this embodiment.

As shown in FIG. 1, the ink jet head 1 comprises a cavity plate 10 and a piezoelectric actuator 20.

In the cavity plate 10, an ink supply port 11, a manifold 12, a throttle unit 13, a pressure chamber 14, a descender hole 15, and a nozzle 16 connected to an ink supply source are formed.

The cavity plate 10 has, for example, 4
Made of 2% nickel alloy steel plate (42 alloy), 50 μm to 1
It has a structure in which a plurality of metal plates having a thickness of about 50 μm are formed, and each is overlapped and bonded with an adhesive. However, it is not limited to metal and may be formed of, for example, resin.

The piezoelectric actuator 20 has a structure in which, for example, a piezoelectric sheet, an insulating sheet, a drive electrode and the like are laminated, and the pressure chamber 1 of the cavity plate 10 is formed.
4 is mounted over the open surface.

The driving device 30 has an image memory 31 for storing dot information to be printed, which is input from the outside, and has dot information to be printed in the current printing cycle and the next printing cycle based on the dot information in the memory 31. Dot information discriminating means 32 for discriminating whether or not, a driving waveform memory 33 for storing a plurality of types of driving waveforms, and a driving waveform selection for selecting one driving waveform from the driving waveform memory 33 based on output information of the dot information discriminating means 32 Means 34, an output circuit 3 for supplying dot information in the image memory 31 to the piezoelectric actuator 20 with a selected drive waveform on a clock signal
5 is provided.

In such a configuration, when a driving pulse is supplied to the driving electrodes of the piezoelectric actuator 20 by the driving device 30, distortion in the stacking direction due to the piezoelectric effect occurs. Then, the pressure due to this distortion causes the pressure chamber 1
When the internal volume of the pressure chamber 4 is reduced, the ink in the pressure chamber 14 is ejected from the nozzles 16 in the form of droplets, and predetermined printing is performed.

At this time, the ink flow path is composed of an ink supply port 11, a manifold 12, a throttle unit 13, a pressure chamber 14, a descender hole 15, and a nozzle 16 from the upstream.

Next, the ink ejection control of the ink jet head 1 by the driving device 30 in this embodiment will be described in detail.

In this embodiment, FIG.
As shown in (B), a normal waveform H1 output within the printing cycle T while having the same number of ejection pulses for one dot, and a long waveform H2 output over two printing cycles T Are used. Note that the waveform H
1, H2 is an example in which three ejection pulses are output for one dot, and these are stored in the drive waveform memory 33.

In FIG. 2A, the waveform H1 output at the time t0 is a normal waveform composed of three ejection pulses and one cancel pulse. on the other hand,
The waveform H2 output at a timing having a delay time of td from the time t1 is a long waveform. This long waveform is composed of three ejection pulses and two cancellation pulses, and the entire length is longer than the printing cycle T.

This long waveform H2 is used when the next printing cycle of the dot to be printed at present is a printing cycle in which printing is not performed, and is a waveform that can effectively suppress the generation of satellites.

In the example of FIG. 2A, the first dot is formed in the first printing cycle T starting from time t0, and then the second dot is formed in the second printing cycle T starting from time t1. Is formed, but in the third printing cycle T starting from the next time t2, there is no dot to start forming.

In the example of FIG. 2B, the first printing cycle T starting from time t0 has no dots to be formed, and the second printing cycle T starting from time t1. , The formation of the first dot is started, but in the third printing cycle T starting from the next time t2,
This is the case where there is no dot to start forming.

In these cases, the second printing cycle T
Even if a part of the drive waveform takes the third printing cycle T because the entire length of the drive waveform whose output is started is long or the output timing of the drive waveform is late, There is no drive waveform affected by

Therefore, in this embodiment, when the next printing cycle of the dot to be printed at present is a printing cycle in which printing is not performed, the long waveform H2 is used as a driving waveform, and The output is performed at a timing delayed by the delay time td from the normal waveform H1.

As a result, it is possible to output the cancel pulse at a preferable timing in the long waveform, and to output the cancel pulse twice in the case shown in FIG. So you can
Even when a plurality of ejection pulses are output for one dot, the pressure fluctuation in the pressure chamber 14 can be reliably stabilized. Therefore, generation of satellite and unstable ejection can be reliably prevented.

Since the long waveform is output with a delay time td behind the output timing of the normal waveform, as shown in FIG.
Even if the next dot after the dot formed in the first printing cycle T starting from 0 is printed,
As shown in (A), a cancel pulse can be added to the drive waveform used in the first printing cycle T. As a result, when a plurality of ejection pulses are output for one dot, the pressure fluctuation in the pressure chamber 14 can be reliably stabilized.

On the other hand, as shown in FIG. 3A, when the long waveform H2 is output at the timing of time t1, the cancel pulse output in the first printing cycle T starting from time t0. From the long waveform H2
The time until the first pulse of is shortened. As a result, the residual pressure in the pressure chamber 14 is not sufficiently attenuated, so that the ink is not stably ejected by the long waveform H2.

As shown in FIG. 3B, when there is no driving waveform output in the first printing cycle T starting from time t0, even if the long waveform is output at the timing of time t1, it is stable. Discharge can be performed. However, in this case, even if the long waveform H2 is output with a delay time of td as shown in FIG.
The same result as in the case of FIG. 3B is obtained.

Therefore, as in the present embodiment, when the printing cycle next to the currently printing dot is a printing cycle in which printing is not performed, the presence or absence of printing of the dot before the currently printing dot is determined. Regardless, by outputting the long waveform uniformly with a delay time of td,
With a simple configuration, stable ink ejection can be performed.

In the above embodiment, an example is described in which two types of waveforms are used, a normal waveform output within one printing cycle and a long waveform output over two printing cycles. However, the present invention is not limited to such a configuration. For example, although the waveforms are mutually output within one printing cycle, one is a drive waveform having one cancel pulse, and the other is a drive waveform having two cancel pulses.
If the next drive cycle of the dot to be printed is a print cycle in which printing is not performed, the drive waveform having two cancel pulses is represented by t
The output may be performed with a delay time of d.

Further, the length of the delay time td may be appropriately selected from the size or shape of the pressure chamber 14 as appropriate. In addition, the inkjet head 1
The optimal value may be selected based on the ambient temperature or the like.

[0042]

According to the driving apparatus of the ink ejecting apparatus according to the first aspect, when a plurality of driving pulses are continuously output so as to form one dot by a plurality of ink droplets, the dot of the current printing cycle is output. If the information is ejection and the dot information of the next printing cycle is non-ejection, the drive pulse is output with a predetermined time delay from the printing cycle, so that the plurality of continuously output drive pulses Can reliably attenuate the residual pressure in the pressure chamber, and can stably eject ink. Moreover, generation of satellites can be reliably prevented.

According to the second aspect of the present invention, when a plurality of the drive pulses are continuously output so as to form one dot by a plurality of ink droplets, the dot information of the current printing cycle is output. Is the ejection, and when the dot information of the next printing cycle is non-ejection, the driving pulse is output not only by delaying the printing cycle by a predetermined time, but also over the adjacent printing cycle. Since a plurality of pulses are continuously output, even if the drive waveform output by the drive pulse delayed by the predetermined time is a long drive waveform, the pulse can be output in a short print cycle.

According to a third aspect of the present invention, the plurality of continuously output drive pulses include a cancel pulse for attenuating a pressure fluctuation in the pressure chamber. Can be stabilized even when a plurality of the pressure chambers are continuously output. Further, when the dot information of the current printing cycle is ejection and the dot information of the next printing cycle is non-ejection, the driving pulse is output with a predetermined time delay from the printing cycle, so that the current printing is performed. Even if a drive pulse including the cancel pulse is output in a printing cycle earlier than the cycle, a sufficient time is provided for reducing the pressure fluctuation in the pressure chamber, and the pressure fluctuation in the pressure chamber is surely reduced. Stabilization can be achieved.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a piezoelectric inkjet head and a driving device according to an embodiment of the present invention.

2A and 2B are diagrams showing driving waveforms output by the driving device of FIG. 1; FIG. 2A shows a case where a printing cycle, a printing cycle, a non-printing cycle, and a printing cycle are arranged; It is a figure which shows the case where a printing cycle, a printing cycle, a non-printing cycle, and a printing cycle are arranged.

FIG. 3 is a diagram showing driving waveforms according to a conventional method;
(A) is a case where a printing cycle, a printing cycle, a non-printing cycle, and a printing cycle are arranged, (B) is a non-printing cycle, a printing cycle,
FIG. 4 is a diagram illustrating a case of a non-printing cycle and a printing cycle.

[Explanation of symbols]

 Reference Signs List 1 inkjet head 10 cavity plate 11 ink supply port 12 manifold 13 throttle section 14 pressure chamber 15 descender hole 16 nozzle 20 piezoelectric actuator 30 driving device

Claims (3)

[Claims] 1. An ink jet apparatus comprising: a cavity plate having a pressure chamber for discharging ink droplets; and an actuator for changing a pressure in the pressure chamber, the ink jet apparatus being sequentially formed along a direction of relative movement with a recording medium. A drive device that outputs a drive pulse to the actuator at a predetermined printing cycle based on dot information to be printed, and outputs a plurality of the drive pulses continuously to form one dot with a plurality of ink droplets. When the dot information of the current printing cycle is ejection and the dot information of the next printing cycle is non-ejection, the drive pulse is output with a predetermined time delay from the printing cycle. The driving device of the ink ejecting device. 2. The method according to claim 1, wherein when the plurality of drive pulses are continuously output so as to form one dot with a plurality of ink droplets, dot information of a current printing cycle is ejection, and dot information of a next printing cycle is discharged. 2. The driving apparatus according to claim 1, wherein when the ejection is not performed, the plurality of the driving pulses are continuously output so as to extend over an adjacent printing cycle. 3. The driving apparatus for an ink jet apparatus according to claim 1, wherein the plurality of continuously output drive pulses include a cancel pulse for reducing pressure fluctuation in the pressure chamber. .