Patent Application
20120062633
This application is based upon and claims the benefit of priority from prior Japanese Patent Applications No. 2010-202161, filed on Sep. 9, 2010; and No. 2011-185791, filed on Aug. 29, 2011, the entire contents of all of which are incorporated herein by reference.
Embodiments described herein relate generally to a driving apparatus and a driving method of a shared-wall-type inkjet head.
There has been known an inkjet head that uses shear deformation of a piezoelectric member to eject ink drops from nozzles. Such an inkjet head is a so-called shared-wall-type inkjet head and mainly used in an inkjet printer. The shared-wall-type inkjet head enables so-called multi-drop gradation printing by effecting control so that one or more ink drops can be ejected from the nozzles in accordance with a gradation.
However, the shared-wall-type inkjet head has a problem that volumes of ink drops ejected from the nozzles differ and high-quality printing cannot be carried out when the gradation printing is performed.
In general, according to one embodiment, a driving apparatus of an inkjet head includes a drive signal output unit, an ejection pulse number decision unit, a pulse addition determination unit, and a drive signal generation unit.
The drive signal output unit outputs to an actuator a drive signal including ejection pulses which are used to generate pressure oscillation for ejecting ink drops from a nozzle in a pressure chamber associated with this nozzle. The ejection pulse number decision unit decides the number of ejection pulses based on a gradation value of print data. The pulse addition determination unit determines whether a control pulse for intensifying the pressure oscillation is to be added to the drive signal including the ejection pulses.
When the pulse addition determination unit has determined that the control pulse is not to be added, the drive signal generation unit generates a drive signal including ejection pulses whose number has been decided by the ejection pulse number decision unit. When the pulse addition determination unit has determined that the control pulse is to be added, the drive signal generation unit generates a drive signal including ejection pulses whose number is smaller than the number decided by the ejection pulse number decision unit.
An embodiment of a driving apparatus and a driving method of a shared-wall-type inkjet head will now be described hereinafter with reference to the drawings.
The inkjet head 1 ejects an ink, which is supplied from the ink supply opening 6, from the nozzles 2 in accordance with a drive signal generated from the driver IC 4. Further, the inkjet head 1 ejects from the ink ejection opening 7 an ink which has not been ejected from the nozzles 2 in the ink which has flowed in from the ink supply opening 6.
The head main body 3 has a base substrate 15 as a base. Furthermore, in the head main body 3, a frame member 17 is joined and connected to the upper side of this base substrate 15, and a piezoelectric member 14 is joined and connected in the frame member 17.
In the head main body 3, a nozzle plate 16 is bonded to the upper side of the frame member 17. Moreover, in the head main body 3, a space in a central part surrounded by the base substrate 15, the piezoelectric member 14, and the nozzle plate 16 is used as an ink supply path 18. Additionally, in the head main body 3, a space in a peripheral part surrounded by the base substrate 15, the piezoelectric member 14, the frame member 17, and the nozzle plate 16 is used as an ink ejection path 19.
Holes 22 communicating with the ink supply path 18 and holes 23 communicating with the ink ejection path 19 are formed in the base substrate 15. The holes 22 communicate with the ink supply opening 6 through the manifold 8. The holes 23 communicate with the ink ejection opening 7 through the manifold 8.
In regard to the base substrate 15, a material having a small dielectric constant and a small difference in thermal expansion coefficient from the piezoelectric member 14 is desirable. For example, the base substrate 15 made of a material such as alumina (Al2O3), a silicon nitride (Si3N4), a silicon carbide (SiC), an aluminum nitride (AlN), or a piezoelectric zirconate titanate (PZT) is used. In this embodiment, the piezoelectric zirconate titanate (PZT) having a small dielectric constant is used.
The piezoelectric member 14 is obtained by laminating on a first piezoelectric member 14a a second piezoelectric member 14b having a polarity opposite to that of this first piezoelectric member 14a. The first piezoelectric member 14a and the second piezoelectric member 14b are bonded to each other.
Long grooves 26 connected to the ink ejection path 19 from the ink supply path 18 are formed in the piezoelectric member 14 in parallel. Further, electrodes 21 are provided on inner surfaces of the respective long grooves 26. Each electrode 21 is connected with the driver IC 4 through each wiring line 20.
A space surrounded by each long groove 26 and a back surface of the nozzle plate 16 bonded to the upper side of the second piezoelectric member 14b to cover each long groove 26 functions as a pressure chamber 24. Furthermore, the nozzle 2 communicates with each pressure chamber 24 in a one-to-one relationship.
The piezoelectric member 14 forming a partition wall between the pressure chambers 24 adjacent to each other is sandwiched between the electrodes 21 of the respective pressure chambers 24. As a result, an actuator 25 is constituted by the piezoelectric member 14 and the electrodes 21 provided on both sides of this member 14.
When an electric field is applied by a drive signal generated in the driver IC 4, the actuator 25 shear-deforms into a sideling V shape with a joint portion between the first piezoelectric member 14a and the second piezoelectric member 14c being used as a vertex. Based on this deformation of the actuator 25, a volume of the pressure chamber 24 changes, and the ink provided in the pressure chamber 24 is pressurized. The pressurized ink is ejected from the nozzle 2 communicating with this pressure chamber 24.
In regard to the piezoelectric member 14, a piezoelectric zirconate titanate (PZT), a lithium niobate (LiNbO3), or a lithium tantalite (LiTaO3) is used as a material. In this embodiment, the piezoelectric zirconate titanate (PZT) having a high piezoelectric constant is used.
The electrode 21 has a double structure of nickel (Ni) and gold (Au). The electrode 21 is uniformly generated in the long groove 26 by a plating method. Besides the plating method, a sputtering method or a vapor deposition method can be used as the method of generating the electrode 21. The pressure chambers 24 are formed into a shape having a depth of 300 μm and a width of 80 μm and aligned with a pitch of 169 μm.
In the nozzle plate 16, the nozzles 2 are formed at positions offset every three cycles from the central part of the pressure chambers 24 in the longitudinal direction. As the nozzle plate 16, a metal material such as stainless, an inorganic material such as single crystal silicon, or a resin material such as polyimide is used. In this embodiment, a polyimide film is used.
The nozzles 2 are formed by bonding the nozzle plate 16 to the piezoelectric member 14 and then performing hole drilling by using an excimer laser. The nozzle 2 has a shape tapered from the back surface side of the pressure chamber 24 side toward the front surface side of the ink ejection side.
When a material of the nozzle plate 16 is stainless, the nozzles 2 can be formed by press work. When a material of the nozzle plate 16 is single crystal silicon, the nozzles 2 can be formed by dry etching or wet etching based on photolithography.
In the following description, a portion which is a combination of one actuator 25, the pressure chamber 24 having one sidewall formed by this actuator 25, and the nozzle 2 communicating with this pressure chamber 24 will be called a channel.
The respective channels are divided into three groups “a”, “b”, and “c”. Specifically, in
The driver IC 4 divides drive signals, which are supplied to the respective channels, into three signals, i.e., an A cycle signal, a B cycle signal, and a C cycle signal. Further, the A cycle signal is supplied to the channels belonging to the group “a”, the B cycle signal is supplied to the channels belonging to the group “b”, and the C cycle signal is supplied to the channels belonging to the groups “c”.
As described above, the driver IC 4 drives the respective channels in accordance with each of (n+1) channel groups in a time sharing manner. Therefore, power is not fed to the channels adjacent to each other in the same cycle.
The drive signal includes ejection pulses which are used to generate pressure oscillation for ejecting ink drops from the nozzle 2 in the pressure chamber 24 associated with this nozzle 2. When the ejection pulses are applied to the actuator 25, a volume of the pressure chamber 24 associated with this actuator 25 changes. Based on this change, ink drops are ejected from the nozzle 2 communicating with this pressure chamber 24.
The driver IC 4 outputs up to four ejection pulses in one cycle. That is, the inkjet head 1 can eject up to four ink drops from one channel in one cycle. A printer including the inkjet head 1 performs gradation printing by controlling the number of ink drops in one cycle of each channel.
In the following description, gradation data when not ejecting an ink drop from the channel in one cycle will be called a gradation value “0”, and gradation data when ejecting four ink drops from the same in one cycle will be called a gradation value “4”.
When the driver IC 4 receives data of a print image from the outside, e.g., a host computer that controls the inkjet printer, it stores a gradation value of this data in the gradation data buffer 41. The gradation data buffer 41 stores gradation values of print data of at least recent three cycles before.
As shown in
The gradation value “2” is determined as a reference to set each evaluation value. When a gradation value of previous printing is smaller than the reference gradation value “2”, i.e., when the number of ejected ink drops is small, the evaluation value is a positive value. This value tends to increase in the later cycle. Further, the evaluation value is increased as the number of ejected ink drops is reduced, i.e., as the gradation value is reduced.
Conversely, when a gradation value of previous printing is larger than the reference gradation value “2”, i.e., when the number of ejected ink drops is large, the evaluation value is a negative value. This value tends to increase in the later cycle. Furthermore, the evaluation value is increased as the number of ejected ink drops is increased, i.e., as the gradation value is increased.
In this embodiment, the respective evaluation values of one cycle before, two cycles before, and three cycles before are set to “0” with respect to the reference gradation value “2”. Moreover, the evaluation value of one cycle before is set to “5”, the evaluation value of two cycles before is set to “3”, and the evaluation value of three cycles before is set to “2” with respect to the gradation value “1” smaller than this gradation value “2”. Additionally, the evaluation value of one cycle before is set to “10”, the evaluation value of two cycles before is set to “6”, and the evaluation value of three cycles before is set to “4” with respect to the further smaller gradation value “0”.
Conversely, the evaluation value of one cycle before is set to “−5”, the evaluation value of two cycles before is set to “−3”, and the evaluation value of three cycles before is set to “−2” with respect to the gradation value “3” larger than the gradation value “2”. The evaluation value of one cycle before is set to “−10”, the evaluation value of two cycles before is set to “−6”, and the evaluation value of three cycles before is set to “−4” with respect to the further large gradation value “4”.
The arithmetic operation unit 43 executes arithmetic processing using a procedure shown in a flowchart of
As described above, the drive signals are divided into three signals, i.e., the A cycle signal, the B cycle signal, and the C cycle signal. Additionally, each cycle signal is supplied to three adjacent channels in accordance with each print cycle in a time sharing manner. Therefore, in the processing of Act 1, the arithmetic operation unit 43 acquires a total of three gradation values, i.e., a gradation value of print data of three cycles before supplied to the drive channel, a gradation value of print data of two cycles before supplied to one adjacent channel, and a gradation value of print data of one cycle before supplied to the other adjacent channel from the gradation data buffer 4.
Then, the arithmetic operation unit 43 makes reference to the evaluation value table 42 to convert all the acquired gradation values into evaluation values (Act 2). Further, the arithmetic operation unit 43 adds up the converted evaluation values to calculate a total value of the evaluation values (Act 3).
For example, it is assumed that the gradation value of the print data of one cycle before is “1”, the gradation value of the print data of two cycles before is “3”, and the gradation value of the print data of three cycles before is “4”. Then, the gradation value of the print data of one cycle before is converted into the evaluation value “5”, the gradation value of the print data of two cycles before is converted into the evaluation value “−3”, and the gradation value of the print data of three cycles before is converted into “−4”. Therefore, the arithmetic operation unit 43 calculates a total value “−2” of the evaluation values.
Subsequently, the arithmetic operation unit 43 determines whether the total value of the evaluation values is a negative value (Act 4: the pulse addition determination unit). When the total value of the evaluation values is not a negative value, i.e., when it is “0” or a positive value, the number of ink drops ejected from the drive channel and the adjacent channels on both sides of this channel is relatively small in printing of recent one cycle to three cycles before. At this time, the ejection rate of the ink drops ejected from the drive channel is stable. Therefore, in the current print cycle, a control pulse required to intensify pressure oscillation does not have to be added to the drive signal in this print cycle.
Thus, when the total value of the evaluation values is not a negative value (NO in Act 4), the arithmetic operation unit 43 sets the number of ink drops ejected from the drive channel to be equal to the gradation value in the current print cycle (Act 5: the ejection pulse number decision unit). That is, if the gradation value is “0”, the number of ink drops is also “0”. If the gradation value is “1”, the number of ink drops is also “1”. This is also applied to a situation where the gradation value is “2”, “3”, or “4”.
The arithmetic operation unit 43 generates waveform information of the drive signal including ejection pulses whose number coincides with this gradation value (the drive signal generation unit). Further, the arithmetic operation unit 43 outputs this waveform information to the drive signal generation unit 44 (Act 9).
On the other hand, when the total value of the evaluation values is a negative value, the number of ink drops ejected from the drive channel and the adjacent channels on both sides is relatively large in printing of recent one cycle to three cycles before. At this time, the ejection rate of ink drops ejected from the drive channel is reduced. Therefore, in the current print cycle, to increase the ejection rate of the ink drops, the control pulse must be added to the drive signal.
Therefore, when the total value of the evaluation values is a negative value (YES in Act 4), the arithmetic operation unit 43 generates and temporarily stores information indicating that the control pulse is added to the drive signal having ejection pulses (Act 6). Then, the arithmetic operation unit 43 determines whether the gradation value is larger than “1” (Act 7).
When the gradation value is “1” or “0” (NO in Act 7), the arithmetic operation unit 43 sets the number of ink drops ejected from the drive channel to be equal to the gradation value in the current print cycle (Act 5: the ejection pulse number decision unit). Furthermore, the arithmetic operation unit 43 generates waveform information of the drive signal including a control pulse and ejection pulses whose number is equal to this gradation value (the drive signal generation unit) and outputs this generated information to the drive signal generation unit 44 (Act 9).
On the other hand, when the gradation value is larger than “1” (YES in Act 7), the arithmetic operation unit 43 sets the number of ink drops ejected from the drive channel to a number obtained by subtracting “1” from the gradation value (Act 8: the ejection pulse number decision unit). Moreover, the arithmetic operation unit 43 generates waveform information of the drive signal including a control pulse and ejection pulses whose number is obtained by subtracting “1” from this gradation value (the drive signal generation unit) and outputs the generated information to the drive signal generation unit 44 (Act 9).
The drive signal generation unit 44 outputs the drive signal including a pulse waveform of the waveform information supplied from the arithmetic operation unit 43 to the head main body 3 (the drive signal generation unit).
Each of
In
As shown in
As shown in
As described above, in this embodiment, the control pulses 33 are simultaneously output to the drive channel and the adjacent channels on both sides of this drive channel. As a result, the voltage of the control pulse is not applied to the actuator 25 of the drive channel.
As shown in
Then, the ejection pulse 31 is periodically output to the drive channel in regard to the first drop to the third drop, and the cancellation pulse 32 is output to the same for the fourth drop. On the other hand, the cancellation pulse 32 is periodically output to both the adjacent channels on both sides for the first drop to the fourth drop. The cancellation pulse 32 is output after outputting the ejection pulse 31.
As described above, in this embodiment, the control pulses 33 are simultaneously output to the adjacent channels on both sides of the drive channel, and the control pulse 33 is not output to the drive channel. Adopting this configuration enables the voltage of the control pulse to be applied to the actuator 25 of the drive channel.
Additionally, in this embodiment, when applying the voltage of the control pulse to the actuator 25 of the drive channel, the number of ejection pulses for the drive channel is corrected. Specifically, the correction is performed in such a manner that “1” is subtracted from a number determined based on the gradation value, i.e., “1” is subtracted from the number of ink drops ejected from the drive channel.
Here, output timings for the ejection pulse 31, the cancellation pulse 32, and the control pulse 33 will now be described with reference to
As shown in
When the output timings of the ejection pulse 31, the cancellation pulse 32, and the control pulse 33 are set in this manner, an effect of each pulse can be greatly improved.
[Table 1] shows a combination example of gradation values for three cycles of each of recent print patterns (a pattern “1” to a pattern “9”) and a relationship between a total of evaluation values for the print pattern and presence/absence of addition of the control pulse and correction of ink drops.
The print pattern “1” corresponds to a case where the print gradation value of three cycles before is “0”, the print gradation value of two cycles before is “0”, and the print gradation value of one cycle before is “0”. In this case, based on the set data in the evaluation value table 42, when the print gradation value of three cycles before is “0”, the evaluation value is “4”. When the print gradation value of two cycles before is “0”, the evaluation value is “6”. When the print gradation value of one cycle before is “0”, the evaluation value is “10”. Therefore, a total of the evaluation values is “20”. When the total of the evaluation values is a positive value in this manner, the driver IC 4 does not add the control pulse and does not correct the number of ink drops either.
The print pattern “2” corresponds to a case where the print gradation value of three cycles before is “2”, the print gradation value of two cycles before is “2”, and the print gradation value of one cycle before is “2”. In this case, based on the set data in the evaluation value table 42, when the print gradation value of three cycles before is “2”, the evaluation value is “0”. When the print gradation value of two cycles before is “2”, the evaluation value is “0”. When the print gradation value of one cycle before is “2”, the evaluation value is “0”. Therefore, a total of the evaluation values is “0”. When the total of the evaluation values is not a negative value in this manner, the driver IC 14 does not add the control pulse and does not correct the number of ink drops either.
The print pattern “3” corresponds to a case where the print gradation value of three cycles before is “4”, the print gradation value of two cycles before is “4”, and the print gradation value of one cycle before is “4”. In this case, based on the set data in the evaluation value table 42, when the print gradation value of three cycles before is “4”, the evaluation value is “−4”. When the print gradation value of two cycles before is “4”, the evaluation value is “−6”. When the print gradation value of one cycle before is “4”, the evaluation value is “−10”. Therefore, a total of the evaluation values is “−20”. When the total of the evaluation values is a negative value in this manner, the driver IC 14 adds the control pulse and also corrects the number of ink drops.
The print pattern “4” corresponds to a case where the print gradation value of three cycles before is “0”, the print gradation value of two cycles before is “2”, and the print gradation value of one cycle before is “4”. In this case, based on the set data in the evaluation value table 42, when the print gradation value of three cycles before is “0”, the evaluation value is “4”. When the print gradation value of two cycles before is “2”, the evaluation value is “0”. When the print gradation value of one cycle before is “4”, the evaluation value is “−10”. Therefore, a total of the evaluation values is “−6”. When the total of the evaluation values is a negative value in this manner, the driver IC 14 adds the control pulse and also corrects the number of ink drops.
The print pattern “5” corresponds to a case where the print gradation value of three cycles before is “2”, the print gradation value of two cycles before is “4”, and the print gradation value of one cycle before is “0”. In this case, based on the set data in the evaluation value table 42, when the print gradation value of three cycles before is “2”, the evaluation value is “0”. When the print gradation value of two cycles before is “4”, the evaluation value is “−6”. When the print gradation value of one cycle before is “0”, the evaluation value is “10”. Therefore, a total of the evaluation values is “4”. When the total of the evaluation values is a positive value in this manner, the driver IC 14 does not add the control pulse and does not correct the number of ink drops either.
The print pattern “6” corresponds to a case where the print gradation value of three cycles before is “4”, the print gradation value of two cycles before is “0”, and the print gradation value of one cycle before is “2”. In this case, based on the set data in the evaluation value table 42, when the print gradation value of three cycles before is “4”, the evaluation value is “−4”. When the print gradation value of two cycles before is “0”, the evaluation value is “6”. When the print gradation value of one cycle before is “2”, the evaluation value is “0”. Therefore, a total of the evaluation values is “2”. When the total of the evaluation values is a positive value in this manner, the driver IC 14 does not add the control pulse and does not correct the number of ink drops either.
The print pattern “7” corresponds to a case where the print gradation value of three cycles before is “0”, the print gradation value of two cycles before is “4”, and the print gradation value of one cycle before is “2”. In this case, based on the set data in the evaluation value table 42, when the print gradation value of three cycles before is “0”, the evaluation value is “4”. When the print gradation value of two cycles before is “4”, the evaluation value is “−6”. When the print gradation value of one cycle before is “2”, the evaluation value is “0”. Therefore, a total of the evaluation values is “−2”. When the total of the evaluation values is a negative value in this manner, the driver IC 14 adds the control pulse and also corrects the number of ink drops.
The print pattern “8” corresponds to a case where the print gradation value of three cycles before is “2”, the print gradation value of two cycles before is “0”, and the print gradation value of one cycle before is “4”. In this case, based on the set data in the evaluation value table 42, when the print gradation value of three cycles before is “2”, the evaluation value is “0”. When the print gradation value of two cycles before is “0”, the evaluation value is “6”. When the print gradation value of one cycle before is “4”, the evaluation value is “−10”. Therefore, a total of the evaluation values is “−4”. When the total of the evaluation values is a negative value in this manner, the driver IC 14 adds the control pulse and also corrects the number of ink drops.
The print pattern “9” corresponds to a case where the print gradation value of three cycles before is “4”, the print gradation value of two cycles before is “2”, and the print gradation value of one cycle before is “0”. In this case, based on the set data in the evaluation value table 42, when the print gradation value of three cycles before is “4”, the evaluation value is “−4”. When the print gradation value of two cycles before is “2”, the evaluation value is “0”. When the print gradation value of one cycle before is “0”, the evaluation value is “10”. Therefore, a total of the evaluation values is “6”. When the total of the evaluation values is a positive value in this manner, the driver IC 14 does not add the control pulse and does not correct the number of ink drops either.
As shown in [Table 1], in this embodiment, when a total of the evaluation values is a negative value, the control pulse 33 is added, and the number of ink drops is corrected. On the other hand, when a total of the evaluation values is not lower than 0, the control pulse 33 is not added, and the number of ink drops is not corrected either.
The print pattern “2” corresponds to the case where the print gradation value of three cycles before is “2”, the print gradation value of two cycles before is “2”, and the print gradation value of one cycle before is “2”. Therefore, in
As shown in [Table 1], the driver IC 4 does not add the control pulse and does not correct the number of ink drops either immediately after the print pattern “2”. That is, a voltage of the control pulse 33 is not applied to actuators 25c1 and 25a2 constituting both sidewalls of the drive channel. Therefore, the control pulse 33 is output to the respective electrodes 21c1, 21a2, and 21b2 immediately before the print cycle (the A cycle).
Outputting this pulse equalizes potentials in electrode 21c1, electrode 21a2, and electrode 21b2. Therefore, an electric field of the control pulse 33 does not function with respect to actuator 25c1 and actuator 25a2. Further, the number of ink drops is not corrected. Therefore, in the print cycle, the ejection pulses 31 associated with the gradation value “4” in number are output to electrode 21a2, thereby ejecting four ink drops.
The print pattern “4” corresponds to the case where the print gradation value of three cycles before is “4”, the print gradation value of two cycles before is “4”, and the print gradation value of one cycle before is “4”. Therefore, in
As shown in [Table 1], the driver IC 4 adds the control pulse and also corrects the number of ink drops immediately after the print pattern “4”. That is, a voltage of the control pulse 33 is applied to actuators 25c1 and 25a2 constituting both the sidewalls of the drive channel. Therefore, the control pulse 33 is output to the respective electrodes 21c1 and 21b2 immediately before the print cycle (the A cycle). The control pulse 33 is not output to electrode 21a2.
Then, potential differences are generated between electrode 21c1 and electrode 21a2 and between electrode 21a2 and electrode 21b2. Therefore, an electric field of the control pulse 33 functions with respect to actuator 25c1 and actuator 25a2. Further, the number of ink drops is corrected. Therefore, in the print cycle, “3” ejection pulses 31, the number of which is a result of subtracting “1” from the gradation value “4”, are output to electrode 21a2, thereby ejecting three ink drops.
As described above, in this embodiment, when the control pulse 33 is generated and the gradation value is not smaller than “2”, the number of times of generation of the ejection pulses 31 is adjusted to be “1” smaller than the gradation value. That is because the ejection volume of ink drops tends to increase when the control pulse 33 is generated, and the ejection volume is further increased when the control pulse 33 is applied.
At the time of applying the control pulse 33 to the actuator 25, reducing the number of ink drops enables the ejection volume of the ink drops to be reduced. As a result, a variation in the ejection volume can be suppressed.
It is to be noted that the correction of ink drops is performed in such a manner that the corrected number of ink drops becomes 1 or above at minimum. That is, when the gradation value is “1”, the correction of ink drops is not performed.
[Table 2] shows variations in ink ejection volume and ink ejection rate when the ink ejection rate is not corrected by using the control pulse 33 in the above-described print patterns “1” to “9”.
Further, [Table 3] shows variations in ink ejection volume and ink ejection rate when the ink ejection rate is corrected by the control pulse 33 but the number of ink drops is not corrected.
Furthermore, [Table 4] shows variations in ink ejection volume and ink ejection rate when the ink ejection rate is corrected and the number of ink drops is corrected by the control pulse 33.
As shown in [Table 4], in this embodiment, the variations in ejection volume and ejection rate due to a difference in the last printing patterns are 4.2 pl and 5.3 m/s, respectively. On the other hand, as shown in [Table 3], the variations in ejection volume and ejection rate when the control pulse is corrected but the number of ink drops is not corrected are 9.1 pl and 5.3 m/s, respectively. Furthermore, as shown in [Table 2], the variations in ejection volume and ejection rate when the control pulse is not controlled and the number of ink drops is not corrected either are 6.8 pl and 7.9 m/s, respectively.
As described above, according to this embodiment, when the control pulse is corrected and the number of ink drops is also corrected, variations in both ejection rate and ejection volume of the ink drops can be sufficiently suppressed.
In the foregoing embodiment, the description has been given as to the configuration where the ink supply path 18 is provided at one end of the pressure chamber 24, the ink ejection path 19 is provided at the other end of the same, and the nozzles 2 are provided at the central part of the pressure chamber 24. However, the application range of the present invention is not restricted thereto, and a configuration where the nozzles are provided at one end of the pressure chamber 24 and the ink supply path is provided at the other end can be also applied.
Moreover, the number of ink drops is reduced by “1” when correcting an ink ejection rate by using the control pulse 33 in this embodiment, the number to be subtracted from the number of ink drops is not restricted to “1”. “2” or a higher value may be subtracted from the number of ink drops to correct a ejection volume.
While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2010-202161 | Sep 2010 | JP | national |
| 2011-185791 | Aug 2011 | JP | national |
