JPH1016212A - Driving of ink jet recording head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the positional shift of dots by correcting the shift of the emitting speed of ink droplets from an ink chamber by the hysteresis of piezoelectric members constituting a wall. SOLUTION: With respect to an ink chamber (n) ready to drive, it is judged whether both adjacent ink chambers n-1, nil are driven during the period from previous driving to lately driving and, when both adjacent ink chambers are together driven in a drive waveform wherein a current supply time is T1 and final voltage is V1 and, when only the adjacent ink chamber n-1 is driven, the ink chamber (n) is driven in a drive waveform wherein a current supply time is T2 and final voltage is V2 and, when both adjacent chambers are not together driven, the ink chamber (n) is driven in a drive waveform wherein a current supply time is T3 and final voltage is V3. The relation between the current supply times T1, T2, T3 and the voltages V1, V2, V3 is set to T1>T2>T3 and V1>V2>V3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for driving an ink jet recording head used in, for example, an on-demand type ink jet printer.

[0002]

2. Description of the Related Art Conventionally, a plurality of ink chambers each having a wall formed by a polarized piezoelectric member called PZT are provided side by side, electrodes are arranged on inner surfaces of both walls of each ink chamber, and a drive pulse is selected for each electrode. An ink jet recording head which performs printing by deforming both walls of an ink chamber to be driven by applying pressure to apply ink to the ink inside the ink chamber and ejecting ink droplets from ink ejection ports is disclosed in, for example, Showa 6
One disclosed in Japanese Patent Application Laid-Open No. 3-252750 is known.

In a recording head of this type, since a wall made of a piezoelectric member is shared between adjacent ink chambers, when a certain ink chamber is driven, pressure fluctuation occurs in the adjacent ink chamber. Therefore, the pressure state in the ink chamber changes depending on whether or not the adjacent ink chamber is driven, and the discharge speed of the ink droplet from the ink discharge port changes accordingly. This change in the ejection speed causes a shift in the landing time of the ink droplets on the paper, that is, a shift in the dot position, and causes a deterioration in print quality. This is generally an important problem of this type of recording head as a problem of crosstalk.

[0004] The problem that the ejection speed differs among the ink chambers due to the difference in the driving pattern will be described below. For example, FIG. 24A shows the case of single nozzle driving in which ink is ejected only from the ink chamber C. A to E
Indicates an ink chamber, and P1 to P6 indicate walls made of a piezoelectric member. In this case, a voltage is applied to the electrodes of the ink chamber C to open the walls P3 and P4 outward, and the ink is filled in the ink chamber C. Then, the voltage application is stopped and the walls P3 and P4 are rapidly restored to the original state. The state returns to the state, and the volume of the ink chamber C is reduced to discharge the ink droplets.

FIG. 24B shows a case of a type of multi-nozzle drive in which ink is simultaneously ejected from every other ink chamber B, D and F. A to G indicate ink chambers, and P1 to P8 indicate walls made of piezoelectric members. In this case, a voltage is applied to the electrodes of the ink chambers B, D and F, and both walls P2 and P3 of the ink chamber B and both walls P4 of the ink chamber D are applied.
, P5, the walls P6, P7 of the ink chamber F are opened outward to fill the ink chambers B, D, F, respectively, and then the voltage application is stopped to stop the walls P2, P3, P4, P5, P6.
, P7 are quickly returned to the original state, and the ink chambers B,
The ink droplets are ejected by reducing the volumes of D and F.

In the case of the single-nozzle drive shown in FIG. 24 (a), looking at the state of the adjacent ink chambers B and D when the walls P3 and P4 are returned to the original state, the walls P3 and P4 are conversely closed. Since the ink chambers suddenly open from the closed state, the adjacent ink chambers B and D become negative pressure, and the walls P3 and P4 are pulled by the force in the direction opposite to the direction in which the walls are to be closed. In the case of the multi-nozzle drive shown in FIG. 24B, for example, the ink chambers C and E on both sides of the ink chamber D are suddenly opened from the state where both walls P3, P4, P5 and P6 are closed. The negative pressure in the ink chambers C and E is larger than that in the case of FIG. 24A, so that the force applied to each wall increases. Therefore, the pressure in the ink chamber D does not increase as compared with the case of the single nozzle drive, and the ejection speed of the ink from the ink chamber D is reduced.

As for the ink chambers B and F, the ink chambers C and E adjacent to the inside have a large negative pressure, but the ink chambers A and G adjacent to the outside are the same as in the case of single nozzle driving. The pressure rise in the ink chambers B and F is smaller than in the case of single nozzle driving, and larger than that in the ink chamber D. Therefore, the ejection speed of the ink from the ink chamber is the largest in the case of the single nozzle drive, the ejection speed of the ink chamber D in the simultaneous drive of the ink chambers B, D, and F is the smallest, and the ink chambers B, F
Is in the middle. in this way,
There is a difference in the ink ejection speed from the target ink chamber when the ink chambers adjacent to the target ink chamber are driven simultaneously and when they are not driven.

As a driving method for avoiding this, Japanese Patent Laid-Open No.
As disclosed in Japanese Patent Application Laid-Open No. 1-76653, there is known a driving method in which each ink chamber is divided into three groups every two ink chambers, and the ink chambers are dividedly driven for each group to discharge ink droplets. This is, as shown in FIG. 25, ink chambers A, B, C,
With respect to D, E, F, G, ..., the ink chambers A, D, G, ... are first driven as shown in (a) and (b), and the ink chambers are moved to (c) and (d) at the next timing. Are driven at the next timing, and the ink chambers C, F,... Are driven at the next timings as shown in (e) and (f).
In this method, the ink chambers are divided and driven in groups such as driving the ink chambers A, D, G,... as shown in FIGS.

In this case, in the ink chambers on both sides of the ink chamber for discharging ink, only one wall always deforms, and the other wall does not deform. Therefore, if the drive frequency is reduced and the timing of each ejection is set to be sufficiently long and the residual vibration in the ink chamber when the adjacent ink chamber is driven is completely attenuated, the next ink chamber is driven. It is considered that even if the ink chambers are driven simultaneously, the ink ejection speed from each ink chamber becomes the same, and there is no difference from the case of single nozzle driving.

However, in a case where the ink chambers are divided into three groups every three and the ink chambers are divided and driven, an ejection experiment was performed using drive pulses as shown in FIG. FIG. 27 shows the ratio of the discharge speed in the multiple nozzle drive of 2 to 7 nozzles when the discharge speed is set to 100%. In addition, 2 to 7 nozzle driving indicates the number of ink chambers used for driving. FIG.
Shows, as an example, a drive pulse waveform applied to each electrode in the case of four nozzle drive. The drive voltage Vm is 20V
Then, gradually increase the voltage, and drive pulse width Tm = 100 μs
The pulse is cut off at ec. The driving cycle T between the ink chambers is 5.5 msec. The driving pulse width Tm
In contrast, the driving cycle T is sufficiently long, and the residual vibration when the adjacent ink chamber is driven is completely attenuated, and the driven ink chamber is not affected by the residual vibration due to the driving of the adjacent ink chamber.

From FIG. 27, the discharge speed in the case of the multi-nozzle drive is lower than that of the single-nozzle drive, and the discharge speed of the ink chambers (nozzles) at both ends of the ink chamber (nozzle) to be driven in the multi-nozzle drive. There is a tendency that the ejection speed of the ink chamber (nozzle) at the center becomes lower than that of the ink jet head. This phenomenon is presumed to be caused by residual strain due to the history of the piezoelectric member. FIG. 28 shows an example of single nozzle drive, in which only the ink chamber C is driven with respect to the ink chambers A to E separated by walls P1 to P6. In this case, as shown in (a) and (b), a voltage that gradually rises is applied to the electrodes of the ink chamber C to expand both walls P3 and P4, and after the ink is filled in the ink chamber C, the voltage is increased. To return the two walls P3 and P4 to the original state, whereby the volume of the ink chamber C is reduced, the internal pressure is increased, and ink is ejected from the ink chamber C. Then, at the next timing, as shown in (c) and (d),
When ink is ejected from the ink chamber C, both walls P3 and P4 are deformed in the same direction in the previous ejection operation.

FIG. 29 shows an example of three nozzle driving.
A case is shown in which ink chambers D, B, and C are driven in this order with respect to ink chambers A to E separated by walls P1 to P6. In this case, as shown in (a) and (b), a voltage that gradually rises is applied to the electrodes of the ink chamber D to expand both walls P4 and P5, and after the ink is filled in the ink chamber D, the voltage is increased. To return the two walls P4 and P5 to the original state, thereby reducing the volume of the ink chamber D and increasing the internal pressure.
The ink is ejected from. And at the next timing
As shown in (c) and (d), a gradually rising voltage is applied to the electrodes of the ink chamber B to expand both walls P2 and P3, and after the ink is filled in the ink chamber B, the voltage is cut off. Walls P2, P
3 is returned to the original state, whereby the volume of the ink chamber B is reduced, the internal pressure is increased, and ink is ejected from the ink chamber B.

At the next timing, as shown in (e) and (f), a voltage that gradually rises is applied to the electrodes of the ink chamber C to expand both walls P3 and P4, and the ink chamber C is filled with ink. After that, the voltage is turned off to return the two walls P3 and P4 to the original state, whereby the volume of the ink chamber C is reduced, the internal pressure is increased, and ink is ejected from the ink chamber C. In this case, when the ink is to be ejected from the ink chamber C, the walls P3 and P4 are deformed in the opposite directions in the operation of ejecting the ink from the preceding ink chambers D and B.

By the way, the piezoelectric member has a hysteresis phenomenon. When an electric field is applied, the piezoelectric member is distorted. When the electric field is removed, the distortion does not return to the original position and there is a residual distortion. Therefore, the initial state of the wall is different due to residual distortion between the case where the wall is deformed in the same direction and the case where the wall is deformed in the opposite direction before ejection, and there is a negative residual distortion when deformed in the opposite direction. Therefore, when the same electric field is applied in that state, the amount of displacement of the wall is smaller than when the wall is deformed in the same direction.

For example, FIG. 30 shows an example of 7-nozzle driving. First, as shown in (a) and (b), ink chambers B and P are separated from ink chambers A to I separated by walls P1 to P10. E, H
Are simultaneously driven, and at the next timing, the ink chambers C and F are simultaneously driven as shown in (c) and (d), and at the next timing, the ink chambers D and D are displayed as shown at (e) and (f). G are driven at the same time, and the process returns to the simultaneous driving of the original ink chambers B, E, and H at the next timing.

In this case, the ink chambers B and H at both ends of the ink chamber to be driven are connected to the outer wall P before the ejection operation.
2, P9 is deformed in the same direction. On the other hand, the ink chambers C, D, E, F, and G at the center have both walls deformed in the opposite directions before the ejection operation. This is the same in the case of three nozzle drive, four nozzle drive, five nozzle drive, and six nozzle drive. In the case of single nozzle drive, both walls are always deformed in the same direction. Accordingly, as shown in FIG. 27, in the case of the multi-nozzle drive, the ejection speed is lower than in the case of the single-nozzle drive, and the ink at the center of the ink chamber to be driven is located at the center of the ink chambers (nozzles) at both ends. The discharge speed of the chamber (nozzle) decreases.

Next, a description will be given of a case where an ejection experiment was performed using a drive pulse different from that shown in FIG. In a case where the ink chambers are divided into three groups and the ink chambers are divided and driven, a discharge experiment was performed using a drive pulse as shown in FIG.
FIG. 32 shows the ratio of the discharge speed in the multiple nozzle drive of 2 to 7 nozzles when 0% is set. FIG. 31 shows, as an example, a drive pulse waveform applied to each electrode in the case of four nozzle drive. In this example, the main pulse voltage Vm is 3 V, the pulse width Tm is 18 μsec, the sub-pulse voltage Vs is −19.5 V, and the pulse width Ts is 36 μsec.
c. The wall is slightly widened by the main pulse, and then the wall is narrowed by the sub-pulse to eject ink. The drive cycle T between the ink chambers is 5.5 msec, and the drive cycle T is sufficiently long with respect to the pulse widths Tm and Ts to eliminate the influence of residual vibration when adjacent ink chambers are driven. .

From FIG. 32, in contrast to the case of FIG. 27, the discharge speed in the case of the multi-nozzle drive increases with respect to the single-nozzle drive, and the ink chambers (nozzles) at both ends of the ink chamber (nozzle) to be driven There is a tendency that the discharge speed of the ink chamber (nozzle) at the center is higher than the discharge speed of. This phenomenon is presumed to be caused by residual strain due to the history of the piezoelectric member. FIG. 33 shows an example of single nozzle driving, in which only the ink chamber C is driven with respect to the ink chambers A to E separated by walls P1 to P6. In this case, as shown in (a) to (c), the drive voltage Vm is applied to the electrode of the ink chamber C by the main pulse to expand both walls P3 and P4, and the ink chamber C
Then, a drive voltage Vs is applied to the electrode of the ink chamber C by a sub-pulse to narrow both walls P3 and P4, thereby increasing the pressure in the ink chamber to eject ink droplets. Then, the voltage is turned off to return the two walls P3 and P4 to the original state.

At the next timing, as shown in (d) to (f), the main pulse and the sub-pulse are similarly applied to eject ink from the ink chamber C. At this time, both walls P3 and P4 are deformed in the opposite direction in the previous ejection operation shown in (b).

FIG. 34 shows an example of three nozzle driving.
A case is shown in which ink chambers D, B, and C are driven in this order with respect to ink chambers A to E separated by walls P1 to P6. In this case, as shown in (a) to (c), the drive voltage Vm is applied to the electrode of the ink chamber D by the main pulse, and the two walls P4,
After P5 is expanded and the ink chamber D is filled with ink, a drive voltage Vs is applied to the electrodes of the ink chamber D by sub-pulses to narrow both walls P4 and P5, thereby increasing the pressure in the ink chamber D and increasing the ink pressure. Discharge the droplet. Then, at the next timing, as shown in (d) to (f), the drive voltage Vm is applied to the electrodes of the ink chamber B to expand both the walls P2 and P3, and the ink chamber B is filled with ink. Applies a drive voltage Vs to the electrode of the ink chamber B by a sub-pulse,
P3 is narrowed, thereby increasing the pressure in the ink chamber B to eject ink droplets.

At the next timing, as shown in (g) to (i), the drive voltage Vm is applied to the electrodes of the ink chamber C to expand both walls P3 and P4, and after the ink is filled in the ink chamber C, This time, the drive voltage Vs is applied to the electrode of the ink chamber C by the sub-pulse to narrow both the walls P3 and P4, thereby increasing the pressure in the ink chamber C and ejecting the ink droplets. In this case, when the ink is to be ejected from the ink chamber C, the walls P3 and P4 are deformed in the same direction in the operation of ejecting the ink from the preceding ink chambers D and B.

In the case of driving using the positive main pulse and the negative sub-pulse as described above, the state of the wall before ink ejection is opposite to that shown in FIGS. 28 and 29 in both single nozzle driving and double nozzle driving. Therefore, due to the influence of the residual distortion due to the hysteresis of the piezoelectric member, the discharge speed is higher in the case of the multiple nozzle drive than in the case of the single nozzle drive,
Further, the ejection speed of the ink chamber (nozzle) at the center is higher than that at both ends of the ink chamber to be driven.

[0023]

As described above, conventionally, the discharge speed of ink droplets from the ink chamber changes between single nozzle driving and multiple nozzle driving due to the hysteresis of the piezoelectric member forming the wall. In addition, the ejection speed of the ink droplets from the ink chambers changes between the ink chambers at both ends and the ink chambers at the center in the multi-nozzle drive. And the printing quality could not be sufficiently improved.

Therefore, according to the first to eighth aspects of the present invention, the deviation of the dot position can be prevented by correcting the deviation of the ejection speed of the ink droplet from the ink chamber due to the hysteresis of the piezoelectric member constituting the wall. The present invention provides a method for driving an ink jet recording head capable of sufficiently improving print quality.

[0025]

According to the first aspect of the present invention,
A plurality of ink chambers are provided side by side, electrodes are provided on the inner wall of each ink chamber, and a drive pulse is selectively applied to each electrode to deform the piezoelectric member to apply pressure to ink in the ink chamber to be driven. In an ink jet recording head that performs printing by discharging ink droplets from ink discharge ports, each ink chamber is divided into (n + 1) sets every nth ink unit, and the ink chambers are divided and driven for each set to discharge ink drops. If you do
For the ink chamber to be driven, it is determined whether or not both adjacent ink chambers have been driven between the last drive and the current drive, and based on the determination result, ejection of ink droplets based on the distortion history of the piezoelectric member. The purpose is to change the waveform of the drive pulse so as to correct the change in speed.

According to a second aspect of the present invention, a plurality of ink chambers are provided side by side, electrodes are provided on the inner wall of each ink chamber, and a driving pulse is selectively applied to each of the electrodes to deform the piezoelectric member. In the ink jet recording head that performs printing by opening both walls of the ink chamber to be driven outward and deforming it back to the original state to apply pressure to the ink in the ink chamber and eject ink droplets from the ink ejection ports. 2 ink chambers
When the ink chambers are divided into three groups and the ink chambers are dividedly driven for each group to discharge the ink droplets, the ink chambers to be driven are adjacent to each other between the previous drive and the current drive. It is determined whether or not both ink chambers have been driven, and when both ink chambers are driven together, the ejection speed is higher than when only one of the ink chambers is driven, and only one of the ink chambers is driven. The object of the present invention is to change the waveform of the drive pulse so that the ejection speed is higher when the ink chambers are driven than when both ink chambers are not driven.

According to a third aspect of the present invention, a plurality of ink chambers are provided side by side, electrodes are provided on the inner wall of each ink chamber, and a driving pulse is selectively applied to each electrode to deform the piezoelectric member. The walls of the ink chamber to be driven are deformed so as to be closed and then returned to the inside, or the walls of the ink chamber to be driven are deformed so as to be opened and then closed inside and then returned to the original state. In an ink jet recording head that applies pressure to the ink in the ink chamber and discharges ink droplets from the ink discharge ports to perform printing, the ink chambers are divided into three sets every two ink chambers, and the ink chambers are divided and driven in units of each set. When ejecting ink droplets, it is determined whether or not adjacent ink chambers have been driven between the previous drive and the current drive for the ink chambers to be driven. When driven, one Drive so that the ejection speed is smaller than when only the chambers are driven, and so that the ejection speed is smaller when only one ink chamber is driven than when both ink chambers are not driven. The purpose is to change the pulse waveform.

According to a fourth aspect of the present invention, in the method for driving an ink jet recording head according to the second or third aspect, the waveform of the driving pulse is changed by changing a voltage value.

According to a fifth aspect of the present invention, in the driving method of the ink jet recording head according to the second or third aspect, the waveform of the driving pulse is changed by changing a time from when the wall is opened to when the wall is restored. It is in.

According to a sixth aspect of the present invention, in the method for driving an ink jet recording head according to the fifth aspect, the time from when the wall is opened to when it is restored is determined by the time when the pressure wave propagates one way in the ink chamber in the longitudinal direction. Or, it is set in the vicinity of this.

According to a seventh aspect of the present invention, in the method for driving an ink jet recording head according to the second or third aspect, a pre-pulse is provided before the driving pulse such that the ink is not ejected from the ink chamber, and the pre-pulse is applied to the electrode. The object is to change the ejection speed by changing the application time of the pre-pulse or the time interval between the pre-pulse and the drive pulse.

According to an eighth aspect of the present invention, in the method for driving an ink jet recording head according to the seventh aspect, the application time of the pre-pulse or the time interval between the pre-pulse and the driving pulse is determined by the pressure wave in the longitudinal direction in the ink chamber. The time is set at or near the one-way propagation time.

[0033]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) In this embodiment, an embodiment corresponding to claims 1, 2 and 4 will be described. FIG. 1 is an exploded perspective view showing the structure of an ink jet recording head, partially cut away, and 1 is a substrate made of a ceramic material.
Two rectangular piezoelectric members 2 and 3 are bonded and fixed to the upper front side with an epoxy resin adhesive. The piezoelectric members 2,
3, a plurality of long grooves 4, 4,... Having the same width, the same depth, and the same length are formed in parallel at predetermined intervals by cutting. Electrodes 5, 5,... Are formed on the side and bottom surfaces of the long grooves 4, 4,..., And a lead electrode 6 extending from the rear end of each long groove 4, 4,. ,
6, ... are formed. These electrodes 5, 5, ..., 6,
Are formed by electroless nickel plating.

A PC board 7 is bonded and fixed to the rear side of the substrate 1. A drive IC 8 having a built-in drive circuit is mounted on the PC board 7, and conductive patterns 9, 9,... Connected to the drive IC 8 are formed. .. And the respective lead-out electrodes 6, 6,.
0,...

A top plate 11 made of a ceramic material is bonded and fixed on the piezoelectric member 3 with an epoxy resin adhesive. Further, a nozzle plate 13 provided with a plurality of ink discharge ports 12, 12,... At the tips of the piezoelectric members 2, 3 is bonded and fixed with an adhesive. Thereby, each said long groove 4,
4,... Are covered with the top plate 11 and their ends are closed by the nozzle plate 13, thereby forming ink chambers. A common ink chamber 14 is formed in the top plate 11, and the rear end of the ink chamber formed by the long grooves 4, 4,... Communicates with the common ink chamber 14. The common ink chamber 14 communicates with an ink supply unit (not shown).

FIG. 2 is a partial sectional view of the recording head having the structure shown in FIG. 1 taken along the line XX.
The ink chambers 15, 15,... Formed by 4, 4,. Each of the piezoelectric members 2 and 3 is composed of, for example, a piezo element made of a piezoelectric ceramic, and is polarized in a direction opposite to each other in a plate thickness direction as indicated by an arrow in the drawing.

FIG. 3 is a diagram for explaining a method of driving the recording head. For example, a wall P1 composed of piezoelectric members 2 and 3 is illustrated.
, P2, P3, P3, three ink chambers 15
Focusing on A, 15B and 15C, the central ink chamber 15
Assuming that ink droplets are ejected from B, a positive voltage is applied to the electrode 5 of the ink chamber 15B from the steady state of FIG. 3A to gradually increase the voltage to + V after T time. That is, the driving voltage of the triangular wave shown in FIG. 4 is applied. At this time, the electrodes 5 of the adjacent ink chambers 15A and 15C are kept at the ground potential. The voltage V can be varied by varying the time T.

Thus, each of the walls P 2,
The direction of the electric field applied to P3 is perpendicular to the polarization direction of each of the piezoelectric members 2 and 3, and each of the walls P2 and P3 expands the ink chamber 15B as shown in FIG. 3B by shear mode deformation due to piezoelectric thickness slip. Each deforms outward. Due to the expansion of the ink chamber 15B, ink is supplied from the common ink chamber 14 to the ink chamber 15B. In this state, when the voltage applied to the electrode 5 of the ink chamber 15B is lowered to the ground potential, the walls P2 and P3 return to the original state as shown in FIG. Is rapidly pressurized, and ink droplets are ejected from the corresponding ink ejection port 12.

Since such a recording head utilizes the deformation of a wall, it is impossible to simultaneously drive adjacent ink chambers. Therefore, ink chambers which are not adjacent to each other are divided into two sets or three sets. To drive separately. Here, an example in which the driving is divided into three groups will be described. FIG. 5 shows a drive circuit for applying a drive voltage to the electrode 5 of the ink chamber 15B, and this drive circuit is provided for each electrode of each ink chamber. This drive circuit connects the electrode 5 of the ink chamber 15B to the + Vm terminal via the PNP-type first transistor 21 in the reverse direction, further via the current adjusting resistor 22, and connects the NPN-type second transistor 23. Grounded through the forward direction.

The first transistor 21 has its base connected to the collector of a PNP-type third transistor 24, which is a constant current transistor, and to the + Vm terminal via a resistor 25. The third transistor 2
Reference numeral 4 denotes an emitter connected to the + Vm terminal, a base connected to the emitter of the first transistor 21 via a resistor 26, and a collector connected to a collector of an NPN type fourth transistor 28 via a resistor 27. ing. The fourth transistor 28 has an emitter grounded, a base grounded via a resistor 29 and connected to a signal input terminal s1 via a resistor 30. The second transistor 23 has an emitter grounded, a base grounded via a resistor 31, and connected to a signal input terminal s2 via a resistor 32.

A main pulse signal MP is supplied to the signal input terminal s1, and a ground signal GP is supplied to the signal input terminal s2. In a steady state at the time of non-driving, the main pulse signal MP becomes L (low) level,
The ground signal GP is at the H (high) level, the second transistor 23 is on, the first and fourth transistors 21 and 28 are off, and the electrode 5 is at the ground potential.

When the main pulse signal MP goes high and the ground signal GP goes low, the fourth transistor 28 is turned on, the first transistor 21 is turned on, and the second transistor 23 is turned off. Become. As a result, + Vm is applied to the electrode 5 via the current adjusting resistor 22 and the first transistor 21. At this time, since both ends of the current adjusting resistor 22 are connected between the base and the emitter of the third transistor 24, a constant current flows while being maintained at the potential between the base and the emitter of the third transistor 24, Thereby, the voltage applied to the electrode 5 gradually increases.

When the H level application time of the main pulse signal MP reaches the time T, the voltage applied to the electrode 5 reaches Vm. Then, immediately, the main pulse signal MP goes to the L level and the ground signal GP goes to the H level, so that the second transistor 23 is turned on and the first and fourth transistors 2 and 3 are turned on.
Since the electrodes 1 and 28 are turned off and the electrode 5 is connected to the ground, the electric charge of the electrode 5 is instantaneously discharged to the ground potential. This series of operations is the same for the electrodes of other ink chambers.

Next, the driving method will be described. In order to correct the crosstalk caused by the residual distortion of the wall due to the hysteresis of the piezoelectric members 2 and 3, an ink chamber (nozzle) to be driven as shown in FIG.
For n, it is determined whether or not both adjacent ink chambers (nozzles) n-1 and n + 1 have been driven during the period from the previous drive to the current drive.

When the ink chamber (nozzle) n is driven by the drive pulse shown in FIG. 2B, the adjacent ink chambers (nozzles) n-1 and n + 1 are driven between the previous drive and the current drive. Further, when driven by the drive pulse shown in FIG. 2B, only the adjacent ink chamber (nozzle) n-1 is driven from the previous drive to the current drive, and is driven by the drive pulse shown in FIG. When this is done, both adjacent ink chambers (nozzles) n-1 and n + 1 are used between the previous drive and the current drive.
Is not driven at all.

Accordingly, the energizing time T of the drive pulse shown in FIG.
1 is set to be longer than the energizing time T3 of the driving pulse C in the figure, and the energizing time T2 of the driving pulse B in the figure is set to an intermediate value between T1 and T3. That is, T1>T2> T3 is set. Therefore, the peak voltages V1, V2, V
3 also satisfies V1>V2> V3.

In order to control the energization of such a drive pulse, as shown in FIG.
An energizing pulse generating circuit 43 is provided to drive the driving voltages to V1 and V2.
, V3, the data for setting the energization times T1, T2, T3 of the main pulse signal MP are stored in the storage device 42. Then, when the arithmetic unit 41 receives the print data, the arithmetic unit 41 operates between the two adjacent ink chambers (nozzles) n between the previous drive and the current drive.
It is determined whether −1 and n + 1 have been driven, and appropriate energization time data is read from the storage device 42 and supplied to the energization pulse generation circuit 43. The drive pulse generation circuit 43 generates an appropriate drive pulse from the energization time data and supplies the drive pulse to the head drive circuit 44, whereby the head drive circuit 44 drives the recording head 45. In this manner, in the case of the so-called pulling drive, when the adjacent ink chambers are driven at the previous timing, the ink chamber is ejected by opening both walls of the ink chamber once and then returning to the original state. Since the wall is once deformed in the opposite direction, a negative residual strain remains due to the hysteresis of the piezoelectric member. When the wall is opened by the next ejection operation from that state, the amount of deformation of the wall becomes small and the ejection speed becomes small. Therefore, a large driving voltage is applied to correct this.

That is, the drive pulse shown in FIG. 6A increases the voltage to V1 and the drive pulse shown in FIG. 6B increases the voltage to V2. It is possible to match the ink ejection speed when the ink chambers n-1 and n + 1 are not driven at all. Therefore, it is possible to correct the deviation of the ejection speed of the ink droplet from the ink chamber due to the hysteresis of the piezoelectric member constituting the wall, thereby preventing the deviation of the dot position and sufficiently improving the print quality.

(Second Embodiment) In this embodiment, an embodiment corresponding to claims 1, 3, 5, and 6 will be described. The configuration of the recording head is the same as that of the first embodiment.

FIG. 8 is a diagram for explaining a method of driving the recording head.
3, three ink chambers 15A, 15B separated by P4,
Focusing on 15C, assuming now that ink droplets are ejected from the central ink chamber 15B, a positive voltage Vm is applied to the electrode 5 of the ink chamber 15B for a predetermined time Tm from the steady state of FIG. As a result, as shown in FIG.
P3 is deformed outward, the volume of the ink chamber 15B is rapidly increased, and ink is replenished. After the time Tm, a negative voltage -Vs is applied to the electrode 5 of the ink chamber 15B for a predetermined time Ts. As a result, as shown in FIG.
P3 is deformed inward, the volume of the ink chamber 15B is rapidly reduced, the ink is pressurized, and the ink is ejected from the ink chamber 15B. After time Ts, the electrode 5 of the ink chamber 15B becomes the ground potential, and the ink chamber 15B returns to the original state as shown in FIG. That is, the drive voltage waveform shown in FIG. 9 is applied to the electrode 5 of the ink chamber 15B, whereby ink is ejected from the ink chamber 15B.

FIG. 10 shows a drive circuit for applying a drive voltage to the electrode 5 of the ink chamber 15B. This drive circuit is provided for each electrode of each ink chamber. This drive circuit is connected to the ink chamber 1
The electrode 5B is connected to the + Vm terminal through the PNP first transistor 51 in the reverse direction, and is connected to the -Vs terminal through the NPN second transistor 52 in the forward direction. Further, the electrode 5 of the ink chamber 15B is grounded through a diode 53 in the reverse direction, a third PNP transistor 54 is grounded in the reverse direction, and the diode 55 is forwardly grounded through the diode 55. Transistor 56 is grounded in the forward direction.

The base of the first transistor 51 is grounded via a resistor 57 and further via a fifth transistor 58 of the NPN type, and a resistor 59 is connected between the base and the emitter. The second transistor 52
Has a base grounded via a resistor 60 and a sixth NPN transistor 61, and a resistor 62 is connected between the base and the emitter.

The third transistor 54 has a base connected to a + Vs terminal via a resistor 63 and a PNP
A seventh transistor 64 is connected in the opposite direction to the + 5V terminal. The fifth transistor 58 has its base grounded via a resistor 65 and connected to a signal input terminal s1 via a resistor 66. The sixth transistor 61 has a base grounded via a resistor 67 and connected to a signal input terminal s2 via a resistor 68. The seventh transistor 64 has a base connected to a resistor 69.
To the signal input terminal s3 via
A resistor 70 is connected between the emitters. The fourth transistor 56 has its base grounded via a resistor 71 and connected to the signal input terminal s3 via a resistor 72.

A main pulse signal MP is supplied to the signal input terminal s1, a sub-pulse signal SP is supplied to the signal input terminal s2, and a ground signal GP is supplied to the signal input terminal s3. . In a steady state during non-driving, the main pulse signal MP and the sub-pulse signal SP are at L (low) level, and the ground signal GP is at H (high) level. The sixth transistor 51, 52, 58, 61 is off, the third, fourth, and seventh transistors 54, 56, 64 are on, and the electrode 5 is at ground potential.

In this state, while the sub-pulse signal SP remains at the L level, the main pulse signal MP changes to the H level for the time T1.
When the ground signal GP goes to L level, the first and fifth transistors 51 and 58 are turned on, and the electrode 5 is set at +
Connect to Vm terminal. When the time T1 has elapsed, the main pulse signal MP goes low and the sub-pulse signal SP goes high during the time T2.
1, 58 are off, the second and sixth transistors 52, 61
Is turned on, and the electrode 5 is connected to the -Vs terminal.
When the time T2 elapses, the sub-pulse signal SP becomes L
The level and the ground signal GP become H level, return to the original state, and the electrode 5 becomes the ground potential. This series of operations is the same for the electrodes of other ink chambers.

In this driving method, the main pulse signal MP
By varying the energization time Tm, the ejection speed of the ink from the ink chamber changes as shown in FIG. This is because the pressure state in the ink chamber fluctuates with time, and the cycle is the time when the pressure wave is reflected and returned from one end of the ink chamber to the other in the longitudinal direction. Therefore, half of this time is the time required for one-way propagation from one end of the ink chamber to the other in the longitudinal direction. If the length of the ink chamber is L and the speed of sound in the ink is a, this pressure propagation time is L / a. Becomes

When the main pulse voltage Vm is applied to the electrode 5 and both walls are rapidly expanded, the pressure in the ink chamber becomes negative. When the pressure propagation time elapses, the pressure in the ink chamber is reversed to the positive pressure. By applying the sub-pulse voltage -Vs and sharply narrowing both walls, a higher discharge pressure can be obtained. Therefore, the discharge speed reaches a peak by setting the energizing time Tm of the main pulse to this pressure propagation time.
When the time twice as long as the pressure propagation time elapses after the application of the main pulse voltage Vm, the pressure in the ink chamber reverses from negative pressure to positive pressure and back to negative pressure. If the two walls are sharply narrowed by applying -Vs, a high ejection pressure cannot be obtained this time. Therefore, the ejection time of the ink is set by setting the energization time Tm of the main pulse to twice the pressure propagation time. Speed decreases. Thus, the discharge speed can be corrected by setting the energization time Tm to an appropriate value.

Next, the driving method will be described. In order to correct the crosstalk caused by the residual distortion of the wall due to the hysteresis of the piezoelectric members 2 and 3, as shown in the drive pulse waveform in FIG. 12, the ink chamber (nozzle) n to be driven is driven last time. It is determined whether or not both adjacent ink chambers (nozzles) n-1 and n + 1 have been driven during the period from this time to the current drive.

When the ink chamber (nozzle) n is driven by the drive pulse shown in FIG. 2B, both adjacent ink chambers (nozzles) n-1 and n + 1 are driven at all from the previous drive to the current drive. In addition, when driven by the drive pulse shown in FIG. 2B, only the adjacent ink chamber (nozzle) n-1 is driven from the previous drive to the current drive, and the drive pulse shown in FIG. When driven by the above, both adjacent ink chambers (nozzles) n−1, from the previous drive to the current drive,
n + 1 are driven together.

Therefore, the energizing time of the main pulse is set to T1 in the case of (a), the energizing time of the main pulse is set to T2 in the case of (b), and the energizing time of the main pulse is set to T3 in (c). I do. From the relationship between the main pulse energizing time Tm and the discharge speed v in FIG. 11, T1 is set to the pressure propagation time so that the discharge speed v1 becomes the maximum value, and T2, T3
Is that the discharge speeds v2 and v3 are v3 (T3) <v2 (T2)
<V1 (T1).

In the case of the driving method in which the discharge operation is performed by opening and narrowing both the walls as described above, the discharge operation is completed.
Adjacent ink chambers (nozzles) until the next ejection operation
When both are not driven, the wall is deformed in the direction to be narrowed by the previous ejection operation, so that a negative residual strain remains due to the hysteresis of the piezoelectric member. When the wall is opened and narrowed in the next discharge operation from that state, the amount of deformation of the wall is reduced, and the discharge speed is reduced. On the other hand, when the adjacent ink chamber (nozzle) is driven between the end of the discharge operation and the start of the next discharge operation, the wall is once deformed in the opposite direction (opening direction).
Positive residual strain remains due to the hysteresis of the piezoelectric member. When the wall is opened and narrowed in the next ejection operation from that state, the deformation amount of the wall is increased and the ejection speed is increased as compared with a case where both adjacent ink chambers (nozzles) are not driven.

Therefore, the difference in the discharge speed can be corrected by changing the energization time, that is, by shifting the timing of the pressure fluctuation. Therefore, it is possible to correct the deviation of the ejection speed of the ink droplet from the ink chamber due to the hysteresis of the piezoelectric member constituting the wall, thereby preventing the deviation of the dot position and sufficiently improving the print quality. (Third Embodiment) In this embodiment, an embodiment corresponding to claims 1, 3 and 4 will be described. This embodiment is a modification of the above-described second embodiment. In the second embodiment, the discharge speed is corrected by changing the energization time Tm. In this embodiment, the voltage is changed. To correct the ejection speed. As shown in the drive pulse waveform in FIG. 13, the ink chamber (nozzle) n to be driven from now on
It is determined whether or not both adjacent ink chambers (nozzles) n-1 and n + 1 have been driven between the previous drive and the current drive.

When the ink chamber (nozzle) n is driven by the drive pulse shown in the figure, the adjacent ink chambers (nozzles) n-1 and n + 1 are completely driven from the previous drive to the current drive. In addition, when driven by the drive pulse shown in FIG. 2B, only the adjacent ink chamber (nozzle) n-1 is driven from the previous drive to the current drive, and the drive pulse shown in FIG. When driven by the above, both adjacent ink chambers (nozzles) n−1, from the previous drive to the current drive,
n + 1 are driven together.

Therefore, the potential difference Vm-(-Vs) between the main pulse and the sub-pulse is V1 in the case of A in the drawing, the potential difference Vm-(-Vs) is V2 in the case of B in the drawing, and C in the drawing. Sets the potential difference Vm-(-Vs) to V3. In addition,
V1, V2, and V3 have a relationship of V1>V2> V3.

In the case of a driving method in which the ejection operation is performed by opening and narrowing both walls, when both the adjacent ink chambers (nozzles) are not driven between the end of the ejection operation and the next ejection operation. Since the ejection speed is lower than when adjacent ink chambers (nozzles) are driven between the end of the ejection operation and the next ejection operation, the voltage is increased by that amount to correct the ejection speed.

By changing the voltage in this manner, the difference in the ejection speed can be corrected. Therefore, it is possible to correct the deviation of the ejection speed of the ink droplet from the ink chamber due to the hysteresis of the piezoelectric member constituting the wall, thereby preventing the deviation of the dot position and sufficiently improving the print quality.

(Fourth Embodiment) This embodiment is also an embodiment corresponding to the first, third and fourth aspects and is another modified example of the above-described second embodiment. In the second embodiment, the discharge time is corrected by varying the energization time Tm. In this embodiment, the drive pulse waveform control of the first embodiment is applied to the main pulse. The discharge speed is corrected by varying the energization time Tm and thereby varying the voltage. As shown in the drive pulse waveform in FIG. 14, for the ink chamber (nozzle) n to be driven from now on, both adjacent ink chambers (nozzles) n-1 and n + 1 are driven between the previous drive and the current drive. It is determined whether or not it has been performed.

When the ink chamber (nozzle) n is driven by the drive pulse shown in FIG. 2B, the adjacent ink chambers (nozzles) n-1 and n + 1 are completely driven between the previous drive and the current drive. In addition, when driven by the drive pulse shown in FIG. 2B, only the adjacent ink chamber (nozzle) n-1 is driven from the previous drive to the current drive, and the drive pulse shown in FIG. When driven by the above, both adjacent ink chambers (nozzles) n−1, from the previous drive to the current drive,
n + 1 are driven together.

Therefore, in the case of A in the figure, the voltage of the main pulse is set to V by setting the energizing time Tm of the main pulse to T1.
To 1 and the main pulse conduction time T
By setting m to T2, the voltage of the main pulse is increased to V2, and in the case of C in FIG.
By doing so, the voltage of the main pulse is increased to V3. Note that T1, T2, and T3 are T1>T2> T3, V
1, V2 and V3 are in the relationship of V1>V2> V3.

In the case of a driving method in which the discharge operation is performed by opening and narrowing both walls, when both the adjacent ink chambers (nozzles) are not driven between the end of the discharge operation and the next discharge operation. Since the ejection speed is lower than when adjacent ink chambers (nozzles) are driven between the end of the ejection operation and the next ejection operation, the voltage of the main pulse is increased to compensate for the ejection speed. I do.

By changing the voltage in this way, it is also possible to correct the difference in the ejection speed. Therefore, it is possible to correct the deviation of the ejection speed of the ink droplet from the ink chamber due to the hysteresis of the piezoelectric member constituting the wall, thereby preventing the deviation of the dot position and sufficiently improving the print quality.

(Fifth Embodiment) This embodiment is also an embodiment corresponding to the first, third and fourth aspects. This embodiment is based on the driving pulse waveform of the second embodiment described above. The ink chamber is driven only by the sub-pulse waveform excluding the pulse waveform. That is, in this method, the ink ejection operation is performed by deforming the ink chamber from the steady state to the side where both walls are sharply narrowed, and is a so-called push driving method.

As shown in FIG. 15, the driving pulse waveforms of the ink chambers (nozzles) n to be driven from now on, between the previous driving and the current driving, the two adjacent ink chambers (nozzles) n−1, It is determined whether or not n + 1 has been driven.

When the ink chamber (nozzle) n is driven by the drive pulse shown in FIG. 7B, the adjacent ink chambers (nozzles) n-1 and n + 1 are completely driven from the previous drive to the current drive. In addition, when driven by the drive pulse shown in FIG. 2B, only the adjacent ink chamber (nozzle) n-1 is driven from the previous drive to the current drive, and the drive pulse shown in FIG. When driven by the above, both adjacent ink chambers (nozzles) n−1, from the previous drive to the current drive,
n + 1 are driven together.

Accordingly, the driving voltage is set to V1 in the case of A in the drawing, the driving voltage is set to V2 in the case of B in the drawing, and the driving voltage is set to V3 in the case of C in the drawing. Note that V1,
The absolute values of V2 and V3 have a relationship of V1>V2> V3.

In the case of the driving method in which the discharge operation is performed by sharply narrowing both the walls, if both the adjacent ink chambers (nozzles) are not driven until the discharge operation is completed and the next discharge operation is performed. Since the ejection speed is lower than when adjacent ink chambers (nozzles) are driven between the end of the ejection operation and the next ejection operation, the ejection speed is corrected by increasing the drive voltage accordingly.

By changing the voltage in this manner, the difference in the ejection speed can be corrected. Therefore, it is possible to correct the deviation of the ejection speed of the ink droplet from the ink chamber due to the hysteresis of the piezoelectric member constituting the wall, thereby preventing the deviation of the dot position and sufficiently improving the print quality.

(Sixth Embodiment) This embodiment is an embodiment corresponding to the seventh and eighth aspects. In this embodiment, a pre-pulse is provided before the driving pulse waveform of the second embodiment. Is provided to drive the ink chamber. When changing the ink ejection speed by providing a pre-pulse,
There are two cases: a case where the energization time of the pre-pulse is varied and a case where the interval between the pre-pulse and the drive pulse is varied.

FIG. 16 shows a pulse waveform when the interval between the pre-pulse and the drive pulse is fixed and the energizing time of the pre-pulse is varied, and a temporal pressure change state in the ink chamber due to the pulse waveform. 16A and 16B both set the interval between the pre-pulse and the drive pulse to the pressure propagation time L / a, and the width of the main pulse in the drive pulse also corresponds to the pressure propagation time L / a. You have set. FIG. 16 (a) sets the pre-pulse energizing time to the pressure propagation time L / a, and FIG. 16 (b) sets the pre-pulse energizing time to L / 2a which is half the pressure propagation time. .

When the pre-pulse energizing time is set to the pressure propagation time L / a as shown in FIG. 16 (a), when both walls of the ink chamber are rapidly opened by energizing the pre-pulse, the pressure in the ink chamber becomes negative pressure. When the pressure propagation time L / a elapses, the pressure in the ink chamber is inverted to a positive pressure. When both walls of the ink chamber are returned to the original state in this state, the pressure in the ink chamber increases in positive pressure, and the residual pressure generated by the pre-pulse reverses to negative pressure after the passage of the pressure propagation time L / a. Become. In this state, if both walls are suddenly opened by the energization of the drive pulse, the pressure in the ink chamber will increase the negative pressure,
When the pressure propagation time L / a elapses thereafter, the pressure in the ink chamber is inverted to a positive pressure, and when both walls are closed for ink ejection, the ejection pressure is applied with the residual pressure of the previous prepulse. Larger than,
Ink is ejected at a relatively high ejection speed.

On the other hand, when the pre-pulse energizing time is set to half the pressure propagation time L / 2a as shown in FIG. 16 (b), when the pre-pulse energizing suddenly opens both walls of the ink chamber, The pressure in the chamber becomes a negative pressure, and just after half of the pressure propagation time L / 2a elapses, the pressure in the ink chamber becomes substantially zero. In this state, when the two walls of the ink chamber are returned to the original state, the pressure in the ink chamber becomes a positive pressure.
It does not increase as in (a). Accordingly, since the residual pressure generated by the pre-pulse is smaller than that in the case of FIG. 16A, the discharge pressure by the next drive pulse also becomes small, and as a result, the discharge speed becomes small. That is, in this case, the ink is ejected at a relatively low ejection speed.

As described above, the ejection speed can be varied by providing the pre-pulse before the driving pulse and changing the energization time of the pre-pulse. Therefore, by adjusting the energization time of the pre-pulse, the ejection speed between the ink chambers can be adjusted. The difference can be corrected. Therefore, it is possible to correct the deviation of the ejection speed of the ink droplet from the ink chamber due to the hysteresis of the piezoelectric member constituting the wall, thereby preventing the deviation of the dot position and sufficiently improving the print quality.

FIG. 17 shows a pulse waveform when the interval between the pre-pulse and the drive pulse is varied while keeping the pre-pulse energizing time constant, and a temporal pressure change state in the ink chamber due to the pulse waveform. 17 (a) and (b), the energizing time of the pre-pulse is set to the pressure propagation time L / a, and the width of the main pulse in the drive pulse is also set to the pressure propagation time L / a. And in FIG.
(a) sets the interval between the pre-pulse and the drive pulse to the pressure propagation time L / a, and (b) of FIG. 17 sets the interval between the pre-pulse and the drive pulse to L / 2a which is half the pressure propagation time. Is set to

In the case of FIG. 17 (a), as in the case of FIG. 16 (a), when both walls of the ink chamber are rapidly opened by energizing the pre-pulse, the pressure in the ink chamber becomes negative pressure, and When the time L / a elapses, the pressure in the ink chamber reverses and becomes positive. When both walls of the ink chamber are returned to the original state in this state, the pressure in the ink chamber increases, and the residual pressure generated by the pre-pulse is reduced to the pressure propagation time L / a.
Is reversed, the pressure becomes negative. In this state, when both walls are suddenly opened by energizing the drive pulse, the pressure in the ink chamber increases negative pressure, and after a lapse of the pressure propagation time L / a, the pressure in the ink chamber reverses to become a positive pressure. Further, when both walls are closed for ink ejection, the ejection pressure becomes larger than when there is no pre-pulse because the residual pressure of the previous pre-pulse is applied, and the ink is ejected at a relatively high ejection speed.

On the other hand, when the interval between the pre-pulse and the drive pulse is set to L / 2a which is half of the pressure propagation time as shown in FIG. 17B, the residual pressure due to the pre-pulse is just the pressure propagation time. When the drive pulse is applied in this state, the ink ejection pressure becomes smaller than in FIG. 17A and the ejection speed becomes smaller. That is, in this case, the ink is ejected at a relatively low ejection speed.

As described above, the pre-pulse is provided before the drive pulse, and the ejection speed can be varied by changing the time interval between the pre-pulse and the drive pulse. Therefore, by adjusting this time interval, the ejection between the ink chambers can be performed. The speed difference can be corrected. Therefore, it is possible to correct the deviation of the ejection speed of the ink droplet from the ink chamber due to the hysteresis of the piezoelectric member constituting the wall, thereby preventing the deviation of the dot position and sufficiently improving the print quality.

The pre-pulse used in this embodiment is set to a voltage small enough not to discharge ink from the ink chamber. Therefore, there is almost no hysteresis of the piezoelectric member, and the residual distortion of both walls of the ink chamber is reduced. The state is almost the same with or without the pre-pulse.

FIG. 18 shows an example of a pulse waveform applied to the electrode of the ink chamber when the interval between the pre-pulse and the drive pulse is varied while the energizing time of the pre-pulse is kept constant. ) N
It is determined whether both adjacent ink chambers (nozzles) n-1 and n + 1 have been driven between the last drive and the current drive.

When the ink chamber (nozzle) n is driven by the drive pulse shown in the figure, both adjacent ink chambers (nozzles) n-1 and n + 1 are driven at all from the previous drive to the current drive. In addition, when driven by the drive pulse shown in FIG. 2B, only the adjacent ink chamber (nozzle) n-1 is driven from the previous drive to the current drive, and the drive pulse shown in FIG. When driven by the above, both adjacent ink chambers (nozzles) n−1, from the previous drive to the current drive,
n + 1 are driven together.

Therefore, the time interval between the pre-pulse and the driving pulse is T1 in the case of A in the drawing, the time interval between the pre-pulse and the driving pulse is T2 in the case of FIG. Sets the time interval between the pre-pulse and the drive pulse to T
Set to 3. The relationship between T1, T2, and T3 is T1
>T2> T3. Assuming that the ejection speed at T1 is v1, the ejection speed at T2 is v2, and the ejection speed at T3 is v3, the relationship between v1, v2, and v3 is v1>v2> v3.

When both the adjacent ink chambers (nozzles) are not driven between the end of the ejection operation and the next ejection operation, the wall is deformed in a direction narrowing by the previous ejection operation. Negative residual strain remains due to the hysteresis of the member. When the wall is opened and narrowed in the next discharge operation from that state, the amount of deformation of the wall is reduced, and the discharge speed is reduced.
Therefore, in this case, the time interval between the pre-pulse and the drive pulse is increased to T1 to make a correction to increase the ejection speed.

On the other hand, when both the adjacent ink chambers (nozzles) are driven between the end of the ejection operation and the next ejection operation, the wall is once deformed in the opposite direction (opening direction). Positive residual strain remains due to the hysteresis of the piezoelectric member. When the wall is opened and narrowed in the next ejection operation from that state, the deformation amount of the wall is increased and the ejection speed is increased as compared with a case where both adjacent ink chambers (nozzles) are not driven. Therefore, in this case, the time interval between the pre-pulse and the drive pulse is reduced to T3 to perform the correction for decreasing the ejection speed.

The difference in ejection speed can be corrected by adjusting the pre-pulse energizing time in this manner. Therefore, it is possible to correct the deviation of the ejection speed of the ink droplet from the ink chamber due to the hysteresis of the piezoelectric member constituting the wall, thereby preventing the deviation of the dot position and sufficiently improving the print quality.

FIG. 19 shows an example of pulse waveforms applied to the electrodes of the ink chamber in the case where the interval between the pre-pulse and the drive pulse is made constant and the pre-pulse energizing time is varied. ) N
It is determined whether both adjacent ink chambers (nozzles) n-1 and n + 1 have been driven between the last drive and the current drive.

When the ink chamber (nozzle) n is driven by the drive pulse shown in the drawing, both adjacent ink chambers (nozzles) n-1 and n + 1 are completely driven from the previous drive to the current drive. In addition, when driven by the drive pulse shown in FIG. 2B, only the adjacent ink chamber (nozzle) n-1 is driven from the previous drive to the current drive, and the drive pulse shown in FIG. When driven by the above, both adjacent ink chambers (nozzles) n−1, from the previous drive to the current drive,
n + 1 are driven together.

Therefore, the energizing time of the pre-pulse is set to T1 in the case of (a), the energizing time of the pre-pulse is set to T2 in the case of (b), and the energizing time of the pre-pulse is set to T3 in the case of (c). Note that the relationship between T1, T2 and T3 is T1> T
2> T3. If the discharge speed at T1 is v1, the discharge speed at T2 is v2, and the discharge speed at T3 is v3, the relationship between v1, v2, and v3 is v1
1>v2> v3.

If both adjacent ink chambers (nozzles) are not driven between the end of the ejection operation and the start of the next ejection operation, the wall is deformed in the direction narrowed by the previous ejection operation. Negative residual strain remains due to the hysteresis of the member. When the wall is opened and narrowed in the next discharge operation from that state, the amount of deformation of the wall is reduced, and the discharge speed is reduced.
Therefore, in this case, the time interval between the pre-pulse and the drive pulse is increased to T1 to make a correction to increase the ejection speed.

On the other hand, if both the adjacent ink chambers (nozzles) are driven between the end of the ejection operation and the next ejection operation, the wall is once deformed in the opposite direction (opening direction). Positive residual strain remains due to the hysteresis of the piezoelectric member. When the wall is opened and narrowed in the next ejection operation from that state, the deformation amount of the wall is increased and the ejection speed is increased as compared with a case where both adjacent ink chambers (nozzles) are not driven. Therefore, in this case, the time interval between the pre-pulse and the drive pulse is reduced to T3 to perform the correction for decreasing the ejection speed.

As described above, by adjusting the time interval between the pre-pulse and the drive pulse, it is possible to correct the difference in the ejection speed. Therefore, it is possible to correct the deviation of the ejection speed of the ink droplet from the ink chamber due to the hysteresis of the piezoelectric member constituting the wall, thereby preventing the deviation of the dot position and sufficiently improving the print quality.

Although the embodiments of the present invention have been described above, the application of the present invention is not limited to these embodiments. For example, in the case where the ink chamber of the recording head is driven by pulling, in the first embodiment, a driving voltage of a triangular wave is applied. However, the present invention is not limited to this. For example, as shown in FIG. 20, drive voltages of rectangular waves having different voltages may be used. That is, for the ink chamber (nozzle) n to be driven from now on, both adjacent ink chambers (nozzles) n-
It is determined whether 1, n + 1 has been driven.

When the ink chamber (nozzle) n is driven by the drive voltage V1 shown in FIG. 10B, both adjacent ink chambers (nozzles) n-1 and n + 1 are driven from the previous drive to the current drive. Further, when driven by the drive voltage V2 shown in FIG. 2B, only the adjacent ink chamber (nozzle) n-1 is driven from the previous drive to the current drive, and the drive voltage V shown in FIG. When driven by V3, both adjacent ink chambers (nozzles) n-1 and
n + 1 is not driven at all. Each drive voltage V1, V2, V
The relationship of 3 is V1>V2> V3. Therefore,
When the ink chamber (nozzle) n is driven by the drive voltage V1 shown in FIG. 3A, the ejection speed is corrected to be higher than when it is driven by the drive voltage V3 shown in FIG. In the case where the pulling driving is performed in this manner, the same operation and effect as in the first embodiment can be obtained by adjusting the driving voltage of the rectangular wave.

Further, as shown in FIG. 21, drive voltages of rectangular waves having different energization times may be used. That is, for the ink chamber (nozzle) n to be driven from now on,
It is determined whether both adjacent ink chambers (nozzles) n-1 and n + 1 have been driven between the last drive and the current drive.

When both the adjacent ink chambers (nozzles) n-1 and n + 1 are driven in the period from the previous drive to the current drive, the energizing time of the drive voltage applied to the ink chamber (nozzle) n is shown in FIG. Set to T1 as shown in middle a.
When only the adjacent ink chamber (nozzle) n-1 is driven between the previous drive and the current drive, the energizing time of the drive voltage applied to the ink chamber (nozzle) n is as shown in FIG. Set to T2. In addition, both adjacent ink chambers (nozzles) n-
When 1, n + 1 are not driven at all, the energizing time of the driving voltage applied to the ink chamber (nozzle) n is set to T3 as shown in FIG. Energization time T1, T2 of each drive voltage
, T3 are such that T1>T2> T3.

As described above, by changing the energizing time of the driving voltage, the timing of closing both walls is changed according to the temporal change of the pressure state generated in the ink chamber after the ink chamber is rapidly expanded. Can also change the ink ejection speed. That is, when the ink chamber (nozzle) n is driven by the drive voltage of T1 in the figure, the ejection speed becomes higher than when the ink chamber (nozzle) n is driven by the drive voltage of T3 in the figure. Corrected in the direction. In the case of the pulling driving in this manner, the same operation and effect as in the first embodiment can be obtained by adjusting the energizing time of the rectangular wave driving voltage.

Further, in the case of pulling drive,
As shown in FIGS. 22 and 23, a pre-pulse may be provided before the square-wave drive pulse. FIG. 22 shows a case in which the time interval between the pre-pulse and the drive pulse is changed. For the ink chamber (nozzle) n to be driven,
It is determined whether both adjacent ink chambers (nozzles) n-1 and n + 1 have been driven between the last drive and the current drive.

When both the adjacent ink chambers (nozzles) n-1 and n + 1 are driven in the period from the previous drive to the current drive, the time between the pre-pulse applied to the ink chamber (nozzle) n and the drive pulse The interval is set to T1 as shown in FIG. When only the adjacent ink chamber (nozzle) n-1 is driven between the previous drive and the current drive, the time interval between the pre-pulse applied to the ink chamber (nozzle) n and the drive pulse is shown in FIG. Set to T2 as shown. Further, when both adjacent ink chambers (nozzles) n-1 and n + 1 are not driven at all between the previous drive and the current drive, the time interval between the pre-pulse applied to the ink chamber (nozzle) n and the drive pulse is shown. Set to T3 as shown in middle c. The relationship between the time intervals T1, T2 and T3 is T1>T2> T3. Also in this case, the time interval T1 is set to the pressure propagation time L / a so that the discharge speed becomes the maximum value.

As described above, in the case of the pulling drive, the difference in the ejection speed can be corrected by providing the pre-pulse before the drive pulse and changing the time interval between the pre-pulse and the drive pulse. Therefore, it is possible to correct the deviation of the ejection speed of the ink droplet from the ink chamber due to the hysteresis of the piezoelectric member constituting the wall, thereby preventing the deviation of the dot position and sufficiently improving the print quality.

FIG. 23 shows a case where the energizing time of the pre-pulse is changed. In the ink chamber (nozzle) n to be driven from now on, both ink chambers (nozzles) between the previous drive and the current drive are driven. ) It is determined whether or not n-1 and n + 1 are driven.

When both adjacent ink chambers (nozzles) n-1 and n + 1 are driven together from the previous drive to the current drive, the energizing time of the pre-pulse applied to the ink chamber (nozzle) n is shown in the figure. Set to T1 as shown in a. When only the adjacent ink chamber (nozzle) n-1 has been driven between the previous drive and the current drive, the energizing time of the pre-pulse applied to the ink chamber (nozzle) n is represented by T2 as shown in FIG. Set to. Further, when both adjacent ink chambers (nozzles) n-1 and n + 1 are not driven at all between the previous drive and the current drive, the energizing time of the pre-pulse applied to the ink chamber (nozzle) n is shown in FIG. To T3 as follows. Each time interval T1, T2
, T3 are such that T1>T2> T3. Also in this case, the time interval T1 is set to the pressure propagation time L / a so that the discharge speed becomes the maximum value. As described above, in the case of the pull driving, a difference in the ejection speed can be corrected even if the pre-pulse is provided before the driving voltage and the energizing time of the pre-pulse is changed. Therefore, it is possible to correct the deviation of the ejection speed of the ink droplet from the ink chamber due to the hysteresis of the piezoelectric member constituting the wall, thereby preventing the deviation of the dot position and sufficiently improving the print quality. The driving of the recording head to which the present invention is applied is not limited to the three-division driving.
The method can be applied as long as the ink chambers are divided into (n + 1) sets every other unit and the ink chambers are divided and driven in each set unit.

[0110]

As described above, according to the first to eighth aspects of the present invention, the deviation of the dot position is corrected by correcting the deviation of the ejection speed of the ink droplet from the ink chamber due to the hysteresis of the piezoelectric member constituting the wall. Thus, the print quality can be sufficiently improved.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a configuration of an ink jet recording head according to a first embodiment of the present invention, with a portion cut away.

FIG. 2 is a partial cross-sectional view of the recording head according to the embodiment.

FIG. 3 is a view for explaining a method of driving the recording head in the embodiment.

FIG. 4 is a drive voltage waveform diagram applied to an electrode of an ink chamber in the embodiment.

FIG. 5 is a circuit configuration diagram showing a configuration of a drive circuit for applying a drive voltage to an electrode of an ink chamber in the embodiment.

FIG. 6 is a diagram showing an example of a drive voltage waveform applied to an electrode of an ink chamber in the embodiment.

FIG. 7 is a block diagram showing the configuration of the entire printhead control unit according to the embodiment;

FIG. 8 is a diagram for explaining a method of driving a recording head according to a second embodiment of the present invention.

FIG. 9 is a waveform diagram of a driving pulse applied to an electrode of an ink chamber in the embodiment.

FIG. 10 is a circuit configuration diagram showing a configuration of a drive circuit for applying a drive pulse to an electrode of an ink chamber in the embodiment.

FIG. 11 is a graph showing a relationship between a current supply time of a main pulse signal and an ink ejection speed in the embodiment.

FIG. 12 is a diagram showing an example of a drive pulse waveform applied to an electrode of an ink chamber in the embodiment.

FIG. 13 is a diagram illustrating an example of a drive pulse waveform applied to an electrode of an ink chamber according to a third embodiment of the present invention.

FIG. 14 is a diagram illustrating an example of a drive pulse waveform applied to an electrode of an ink chamber according to a fourth embodiment of the present invention.

FIG. 15 is a diagram illustrating an example of a drive pulse waveform applied to an electrode of an ink chamber according to a fifth embodiment of the present invention.

FIG. 16 is a diagram illustrating an example of a pulse waveform applied to an electrode of an ink chamber and a temporal pressure change state in the ink chamber according to a sixth embodiment of the present invention.

FIG. 17 is a diagram showing another example of a pulse waveform applied to an electrode in the ink chamber and a temporal pressure change state in the ink chamber in the embodiment.

FIG. 18 is a diagram showing an example of a pulse waveform applied to an electrode of an ink chamber when an interval between a pre-pulse and a drive pulse is varied in the embodiment.

FIG. 19 is a diagram showing an example of a pulse waveform applied to an electrode of an ink chamber when the energizing time of a pre-pulse is varied in the embodiment.

FIG. 20 is a diagram showing another example of a driving voltage used in the present invention.

FIG. 21 is a diagram showing another example of a drive voltage used in the present invention.

FIG. 22 is a diagram showing another example of a driving voltage used in the present invention.

FIG. 23 is a diagram showing another example of a driving voltage used in the present invention.

FIG. 24 is a diagram for explaining the operation of a conventional recording head.

FIG. 25 is a view for explaining the operation of a conventional recording head.

FIG. 26 is a diagram showing an example of a drive pulse waveform conventionally applied to an electrode of an ink chamber of a print head.

FIG. 27 is a view for explaining a problem of conventional multi-nozzle driving.

FIG. 28 is a view for explaining the operation of a conventional recording head.

FIG. 29 is a diagram for explaining the operation of a conventional recording head.

FIG. 30 is a view for explaining the operation of a conventional recording head.

FIG. 31 is a diagram showing an example of a drive pulse waveform conventionally applied to an electrode of an ink chamber of a recording head.

FIG. 32 is a view for explaining a problem of conventional multi-nozzle driving.

FIG. 33 is a view for explaining the operation of a conventional recording head.

FIG. 34 is a view for explaining the operation of a conventional recording head.

[Explanation of symbols]

 2, 3 ... piezoelectric member 5 ... electrode 12 ... ink discharge port 15 ... ink chamber

Claims (8)

[Claims] An ink chamber to be driven by deforming a piezoelectric member by selectively applying a drive pulse to each of the plurality of ink chambers, arranging electrodes on the inner wall of each of the ink chambers, and applying a drive pulse to each of the electrodes. In the ink jet recording head which performs printing by applying pressure to the inks of the above and discharging the ink droplets from the ink discharge ports, the ink chambers are divided into (n + 1) groups every n units, and the ink chambers are divided in units of each group. When driving to eject ink droplets, it is determined whether or not both adjacent ink chambers have been driven between the last drive and the current drive for the ink chamber to be driven. A method for driving an ink jet recording head, comprising: changing a waveform of a driving pulse so as to correct a change in an ejection speed of an ink droplet due to a distortion history of a piezoelectric member based on the driving history. 2. An ink chamber to be driven by deforming a piezoelectric member by selectively providing a plurality of ink chambers, arranging electrodes on inner walls of the ink chambers, and selectively applying a driving pulse to each of the electrodes. An ink jet recording head that performs printing by applying pressure to the ink in the ink chamber by deforming the two walls of the ink cartridge to open and then returning the ink chamber to the original state and ejecting ink droplets from the ink ejection ports, In the case where the ink chambers are divided into three sets for each unit and the ink chambers are divided and driven for each set to eject ink droplets,
For the ink chambers to be driven, it is determined whether both adjacent ink chambers have been driven between the last drive and the current drive, and if both ink chambers are driven together, only one of the ink chambers is driven. The waveform of the drive pulse is adjusted so that the ejection speed is higher than when the ink chambers are driven, and when only one ink chamber is driven, the ejection speed is higher than when both ink chambers are not driven. A method for driving an ink jet recording head, wherein the method is changed. 3. Ink chambers to be driven by deforming a piezoelectric member by selectively applying a drive pulse to each of the plurality of ink chambers, arranging electrodes on inner walls of the ink chambers, and selectively applying drive pulses to the respective electrodes. The ink chamber inside the ink chamber is deformed so that both walls of the ink chamber are deformed so as to be closed and then returned to the original state, or both walls of the ink chamber to be driven are opened outward and then closed inside and then returned to the original state. In an ink jet recording head that performs printing by applying pressure and ejecting ink droplets from ink ejection ports, the ink chambers are divided into three sets every two ink chambers, and the ink chambers are divided and driven for each set. When performing the discharge of
For the ink chambers to be driven, it is determined whether both adjacent ink chambers have been driven between the last drive and the current drive, and if both ink chambers are driven together, only one of the ink chambers is driven. The drive pulse waveform is adjusted so that the ejection speed becomes smaller than when the ink chambers are driven, and when only one ink chamber is driven, the ejection speed is smaller than when both ink chambers are not driven. A method for driving an ink jet recording head, wherein the method is changed. 4. The method according to claim 2, wherein a waveform of the driving pulse is changed by changing a voltage value. 5. The method according to claim 2, wherein a waveform of the drive pulse is changed by changing a time from when the wall is opened to when the wall is restored. 6. The time from opening the wall to returning it to the original state,
6. The method according to claim 5, wherein the pressure wave is set at or near a time in which the pressure wave propagates in the ink chamber in one direction in the longitudinal direction. 7. A method in which a pre-pulse that does not cause ink to be ejected from the ink chamber is provided before the drive pulse and applied to the electrode, and the application time of the pre-pulse or the time interval between the pre-pulse and the drive pulse is changed. 4. The method according to claim 2, wherein the ejection speed is changed. 8. The pre-pulse application time or the time interval between the pre-pulse and the drive pulse is set at or near the time when the pressure wave propagates in the ink chamber in one direction in the longitudinal direction. The driving method of the inkjet recording head according to the above.