FIELD
[0001] Embodiments described herein relate generally to a liquid ejection device and an
image forming device.
BACKGROUND
[0002] There is known a liquid ejection device which supplies a predetermined amount of
liquid to a predetermined position. The liquid ejection device is mounted on an inkjet
printer, a 3D printer, a dispensing device, or the like. The inkjet printer ejects
ink droplets from an ink jet head to form an image or the like on a surface of a recording
medium. The 3D printer ejects and cures droplets of a shaping material from a shaping-material
ejection head to form a three-dimensional shaped object. The dispensing device ejects
droplets of a sample and supplies a predetermined amount to a plurality of containers
or the like.
[0003] A liquid ejection device which drives an actuator to eject ink and includes a plurality
of nozzles drives a plurality of actuators at the same phase or drives the actuators
with the phases shifted slightly in order to avoid the concentration of a drive current.
However, if a plurality of actuators are driven at almost the same timing, the ink
ejection may become unstable due to a crosstalk in which the operations of the actuators
interfere with each other.
SUMMARY OF INVENTION
[0004] To solve such problem, there is provided a liquid ejection device, comprising:
a nozzle plate in which a plurality of nozzles for ejecting liquid are arranged two-dimensionally
in an XY direction;
an actuator provided in each of the nozzles;
a liquid supply unit configured to communicate with the nozzles; and
a drive control unit configured to, when one nozzle among the plurality of nozzles
is given attention, give drive signals to actuators of nozzles adjacent the one nozzle
in an X direction and a Y direction, to drive the actuators at a timing shifted by
a predetermined amount from a timing of an actuator of the one nozzle given attention.
[0005] Preferably, the predetermined amount is half of a drive period.
[0006] Preferably still, the predetermined amount is a quarter of a drive period.
[0007] Preferably yet, a half wavelength of a vibration along a surface direction of the
nozzle plate when the actuator is driven is longer than a pitch of arrangement of
the actuator.
[0008] Suitably, the drive control unit further configured to, when one of the plurality
of nozzles is given attention, give drive signals to actuators of nozzles adjacent
the one nozzle in an X direction and a Y direction, drive the actuators of the nozzles
adjacent the one nozzle in the X direction, the actuators of the nozzles adjacent
the one nozzle in the Y direction, or the actuators of the nozzles adjacent the one
nozzle in the X direction and the actuactors of the nozzle adjacent the one nozzle
in the Y direction by drive waveforms with phases reverse to each other.
[0009] The invention also relates to a liquid ejection device, comprising:
a nozzle plate in which a plurality of nozzles for ejecting liquid are arranged two-dimensionally
in an XY direction;
an actuator provided in each of the nozzles;
a liquid supply unit configured to communicate with the nozzles; and
a drive control unit configured to, when one of the plurality of nozzles is given
attention, give drive signals to an actuator of a nozzle adjacent the one nozzle in
an X direction and an actuator of a nozzle adjacent the one nozzle in a -X direction
such that drive waveforms have phases reverse to each other, and give drive signals
to an actuator of a nozzle adjacent the one nozzle in a Y direction and an actuator
of a nozzle adjacent the one nozzle in a -Y direction such that drive waveforms have
phases reverse to each other.
[0010] Preferably, a half wavelength of a vibration along a surface direction of the nozzle
plate when an actuator is driven is longer than a pitch of arrangement of the actuators.
[0011] The invention also concerns a liquid ejection device in which a plurality of nozzles
for ejecting liquid are arranged two-dimensionally in an XY direction, wherein
when one nozzle of the plurality of nozzles is given attention, nozzles adjacent the
one nozzle in an X direction and a -X direction are positioned such that a shift distance
from the one nozzle given attention in a Y-axis direction is (m + 0.5)p, nozzles adjacent
the one nozzle in a Y direction are positioned such that a separation distance from
the one nozzle in the Y-axis direction is (n + 0.5)p, and nozzles adjacent the one
nozzle in a -Y direction are positioned such that a separation distance from the one
nozzle in the Y-axis direction is (n - 0.5)p, wherein
m is a natural number including zero, n is a natural number not including zero, and
p is a dot pitch of a dot formed by the ejected liquid.
[0012] The invention further relates to a liquid ejection device in which a plurality of
nozzles for ejecting liquid are arranged two-dimensionally in an XY direction, wherein
when one nozzle of the plurality of nozzles is given attention, nozzles adjacent the
one nozzle in an X direction and a -X direction are positioned such that a shift distance
from the one nozzle given attention in a Y-axis direction is (m + 0.5)p, nozzles adjacent
the one nozzle in a Y direction are positioned such that a separation distance from
the one nozzle in the Y-axis direction is (n + 0.5)p, and nozzles adjacent the one
nozzle in a -Y direction are positioned such that a separation distance from the one
nozzle in the Y-axis direction is (n - 0.5)p, wherein
m is a natural number including zero, n is a natural number not including zero, and
p is a nozzle pitch in the X direction.
[0013] The invention furhter concerns an image forming device, comprising:
the liquid ejection device above.
[0014] Preferably, the image forming device further comprises: an inkjet head.
DESCRIPTION OF THE DRAWINGS
[0015] The above and other objects, features and advantages of the present invention will
be made apparent from the following description of the preferred embodiments, given
as non-limiting examples, with reference to the accompanying drawings, in which:
FIG. 1 is a configuration diagram of the entire inkjet printer according to a first
embodiment;
FIG. 2 is a perspective view of an ink jet head of the inkjet printer;
FIG. 3 is a plan view of a nozzle plate of the ink jet head;
FIG. 4 is a longitudinal sectional view of the ink jet head;
FIG. 5 is a longitudinal sectional view of the nozzle plate of the ink jet head;
FIG. 6 is a block configuration diagram of a control system of the inkjet printer;
FIG. 7 is a view of a drive signal given to an actuator of the ink jet head;
FIGS. 8A to 8E are views for explaining an operation of the actuator to which the
drive signal is given;
FIGS. 9A to 9C are distribution charts obtained by plotting channel numbers of channels
arranged on the nozzle plate and magnitudes of pressure amplitudes which respective
channels give to an attention channel 108;
FIG. 10 is a graph illustrating an amplitude waveform and a magnitude of amplitude
in a residual vibration which is induced to the attention channel 108 while a channel
109 is driven;
FIG. 11 is a distribution chart obtained by plotting the channel numbers of the channels
arranged on the nozzle plate and magnitudes of pressures which respective channels
give to the attention channel 108;
FIG. 12 is a graph illustrating pressure waveforms (residual vibration waveform) appearing
in the attention channel 108 when a channel 116 and a channel 132 are driven individually;
FIG. 13 is a graph illustrating pressure waveforms (residual vibration waveform) appearing
in the attention channel 108 when a channel 109 and a channel 107 are driven individually;
FIG. 14 is a graph illustrating pressure waveforms (residual vibration waveform) appearing
in the attention channel 108 when a channel 100 and the channel 116 are driven individually;
FIG. 15 is a graph illustrating pressure waveforms (residual vibration waveform) appearing
in the attention channel 108 when a channel 101 and a channel 99 are driven individually;
FIG. 16 is a graph illustrating pressure waveforms (residual vibration waveform) appearing
in the attention channel 108 when a channel 117 and a channel 115 are driven individually;
FIG. 17 is a view for explaining four drive timings A1, A2, B1, and B2 in which time
differences (delay time) are set between drive waveforms for driving channels;
FIG. 18 is a matrix in which the drive timings A1, A2, B1, and B2 are regularly allocated
to all the channels and which illustrates a distribution of the delay times of respective
channels;
FIG. 19 is an arrangement view of nozzles of an ink jet head which is one example
of a liquid ejection device of a second embodiment;
FIG. 20 is a view for explaining a positional relation and a distance of the nozzles;
and
FIG. 21 is a longitudinal sectional view of an ink jet head which is one example of
a liquid ejection device of a third embodiment.
DETAILED DESCRIPTION
[0016] Embodiments provide a liquid ejection device and an image forming device in which
a stable liquid ejection can be performed by preventing a crosstalk in which operations
of actuators interfere with each other.
[0017] In general, according to one embodiment, a liquid ejection device includes a nozzle
plate in which nozzles for ejecting liquid are arranged, an actuator, a liquid supply
unit, and a drive control unit. The actuator is provided in each of the nozzles. The
liquid supply unit communicates with the nozzles. When one of a plurality of nozzles
is given attention, the drive control unit gives drive signals to actuators of nozzles
adjacent in an X direction and a Y direction, to drive the actuators at a timing shifted
by a predetermined amount, such as half of a drive period or a quarter a drive period,
from a timing of an actuator of the nozzle given attention.
[0018] Hereinafter, a liquid ejection device and an image forming device according to the
embodiment will be described with reference to the accompanying drawings. In the drawings,
the same configurations are denoted by the same reference numerals.
First Embodiment
[0019] An inkjet printer 10 which prints an image on a recording medium is described as
one example of an image forming device mounted with a liquid ejection device 1 of
an embodiment. FIG. 1 illustrates a schematic configuration of the inkjet printer
10. For example, the inkjet printer 10 includes a box-shaped housing 11 which is an
exterior body. A cassette 12 which stores a sheet S which is one example of the recording
medium, an upstream conveyance path 13 of the sheet S, a conveyance belt 14 which
conveys the sheet S picked up from the inside of the cassette 12, ink jet heads 1A
to 1D which eject ink droplets toward the sheet S on the conveyance belt 14, a downstream
conveyance path 15 of the sheet S, a discharge tray 16, and a control board 17 are
arranged inside the housing 11. An operation unit 18 as a user interface is arranged
on the upper side of the housing 11.
Data of the image printed on the sheet S is generated by a computer 2 which is external
connection equipment, for example. The image data generated by the computer 2 is transmitted
to the control board 17 of the inkjet printer 10 through a cable 21 and connectors
22B and 22A.
A pickup roller 23 supplies the sheets S one by one from the cassette 12 to the upstream
conveyance path 13. The upstream conveyance path 13 is configured by a feed roller
pair 13a and 13b and sheet guide plates 13c and 13d. The sheet S is fed to the upper
surface of the conveyance belt 14 through the upstream conveyance path 13. An arrow
A1 in the drawing indicates a conveyance path of the sheet S from the cassette 12
to the conveyance belt 14.
The conveyance belt 14 is a reticular endless belt in which a large number of through
holes are formed on the surface. Three rollers, a drive roller 14a and driven rollers
14b and 14c, rotatably support the conveyance belt 14. A motor 24 rotates the conveyance
belt 14 by rotating the drive roller 14a. The motor 24 is one example of a driving
device. In the drawing, A2 indicates a rotation direction of the conveyance belt 14.
A negative pressure container 25 is arranged on a back surface side of the conveyance
belt 14. The negative pressure container 25 is connected to a fan 26 for reducing
pressure, and the inner pressure of the container becomes negative by the air flow
formed by the fan 26. When the inner pressure of the negative pressure container 25
becomes negative, the sheet S is sucked and held on the upper surface of the conveyance
belt 14. In the drawing, A3 indicates the flow of air.
The ink jet heads 1A to 1D are arranged to face the sheet S sucked and held on the
conveyance belt 14 through a slight gap of 1 mm, for example. The ink jet heads 1A
to 1D each eject the ink droplets toward the sheet S. An image is formed on the sheet
S when the sheet passes below the ink jet heads 1A to 1D. The ink jet heads 1A to
1D have the same structure except for the color of the ejected ink. The color of the
ink is cyan, magenta, yellow, or black, for example.
The ink jet heads 1A to 1D are connected through ink passages 31A to 31D with ink
tanks 3A to 3D and ink supply pressure adjusting devices 32A to 32D, respectively.
For example, the ink passages 31A to 31D are resin tubes. The ink tanks 3A to 3D are
containers which store ink. The ink tanks 3A to 3D are arranged above the ink jet
heads 1A to 1D, respectively. During standby, the ink supply pressure adjusting devices
32A to 32D respectively adjust the inner pressures of the ink jet heads 1A to 1D to
be negative compared to the atmospheric pressure, for example, -1 kPa, to prevent
that the ink leaks out from nozzles 51 (see FIG. 2) of the ink jet heads 1A to 1D.
During formation of an image, the inks of the ink tanks 3A to 3D are supplied to the
ink jet heads 1A to 1D by the ink supply pressure adjusting devices 32A to 32D, respectively.
After forming the image, the sheet S is fed from the conveyance belt 14 to the downstream
conveyance path 15. The downstream conveyance path 15 is configured by feed roller
pairs 15a, 15b, 15c, and 15d and sheet guide plates 15e and 15f defining the conveyance
path of the sheet S. The sheet S is fed from a discharge port 27 to the discharge
tray 16 through the downstream conveyance path 15. In the drawing, an arrow A4 indicates
the conveyance path of the sheet S.
Subsequently, the configuration of the ink jet head 1A will be described with reference
to FIGS. 2 to 6. The ink jet heads 1B to 1D have the same structure as the ink jet
head 1A, and the description is not given in detail.
FIG. 2 is a perspective view of the appearance of the ink jet head 1A. The ink jet
head 1A includes an ink supply unit 4 which is one example of a liquid supply unit,
a nozzle plate 5, a flexible board 6, and a drive circuit 7. A plurality of nozzles
51 for ejecting ink are arranged in the nozzle plate 5. The ink ejected from the nozzles
51 is supplied from the ink supply unit 4 communicating with the nozzles 51. The ink
passage 31A from the ink supply pressure adjusting device 32A is connected to the
upper side of the ink supply unit 4. The drive circuit 7 is one example of a drive
control unit. An arrow A2 indicates the rotation direction of the above-described
conveyance belt 14 (see FIG. 1).
FIG. 3 is an enlarged plan view partially illustrating the nozzle plate 5. The nozzles
51 are two-dimensionally arranged in a column direction (X direction) and a row direction
(Y direction). However, the nozzles 51 arranged in the row direction (Y direction)
are obliquely arranged such that the nozzles 51 are not overlapped on the axis of
a Y axis. The nozzles 51 are arranged to have gaps of a distance X1 in the X-axis
direction and a distance Y1 of in the Y-axis direction. As one example, the distance
X1 is about 42.25 µm, and the distance Y1 is about 253.5 µm. That is, the distance
X1 is determined such that a recording density of 600 DPI is formed in the X-axis
direction. The distance Y1 is determined to print at 600DPI in the Y-axis direction.
When eight nozzles 51 arranged in the Y direction are set as one set, plural sets
of nozzles 51 are arranged in the X direction. Although not illustrated, for example,
150 sets of nozzles are arranged in the X direction, and thus a total of 1,200 nozzles
51 are arranged.
An actuator 8 serving as a driving source of the operation of ejecting ink is provided
at each of the nozzles 51. Each actuator 8 is formed in an annular shape and is arranged
such that the nozzle 51 is positioned at the center thereof. One set of the nozzles
51 and the actuator 8 configure one channel. For example, the size of the actuator
8 is an inner diameter of 30 µm and an outer diameter of 140 µm. The actuators 8 are
connected electrically with the individual electrodes 81, respectively. In the actuators
8, eight actuators 8 arranged in the Y direction are connected electrically by a common
electrode 82. The individual electrodes 81 and the common electrodes 82 are connected
electrically with a mounting pad 9. The mounting pad 9 serves as an input port for
giving a drive signal (electric signal) to the actuator 8. The individual electrodes
81 give the drive signals to the actuators 8, respectively. The actuators 8 are driven
according to the given drive signals. In FIG. 3, the actuator 8, the individual electrode
81, the common electrode 82, and the mounting pad 9 are described by a solid line
for convenience of explanation. However, these units are arranged inside the nozzle
plate 5 (see the longitudinal sectional view of FIG. 4). Naturally, the actuator 8
is not necessarily arranged inside the nozzle plate 5.
The mounting pad 9 is connected electrically with a wiring pattern formed in the flexible
board 6 through an anisotropic contact film (ACF), for example. The wiring pattern
of the flexible board 6 is connected electrically with the drive circuit 7. The drive
circuit 7 is an integrated circuit (IC), for example. The drive circuit 7 generates
the drive signal which is given to the actuator 8.
FIG. 4 is a longitudinal sectional view of the ink jet head 1A. As illustrated in
FIG. 4, the nozzle 51 penetrates the nozzle plate 5 in a Z-axis direction. For example,
the size of the nozzle 51 is a diameter of 20 µm and a length of 8 µm. A plurality
of pressure chambers (individual pressure chamber) 41 communicating with the respective
nozzles 51 are provided inside the ink supply unit 4. The pressure chamber 41 is a
cylindrical space of which the upper portion is open, for example. The upper portions
of the pressure chambers 41 are open and communicate with a common ink chamber 42.
The ink passage 31A communicates with the common ink chamber 42 through an ink supply
port 43. The pressure chambers 41 and the common ink chamber 42 are filled with ink.
In some cases, the common ink chamber 42 is formed in a passage shape for circulating
ink, for example. For example, the pressure chamber 41 is configured such that a cylindrical
hole having a diameter of 200 µm is formed in a single crystal silicon wafer having
a thickness of 500 µm. For example, the ink supply unit 4 is configured such that
the space corresponding to the common ink chamber 42 is formed in alumina (Al
2O
3).
FIG. 5 is an enlarged view partially illustrating the nozzle plate 5. The nozzle plate
5 has a structure in which a protective layer 52, the actuator 8, and a diaphragm
53 are laminated in order from the bottom surface side. The actuator 8 has a structure
in which a lower electrode 84, a thin plate-shaped piezoelectric body 85 which is
one example of a piezoelectric element, and an upper electrode 86 are laminated. The
upper electrode 86 is connected electrically with the individual electrode 81, and
the lower electrode 84 is connected electrically with the common electrode 82. An
insulating layer 54 for preventing the short circuit of the individual electrode 81
and the common electrode 82 is interposed at the boundary between the protective layer
52 and the diaphragm 53. For example, the insulating layer 54 is formed of a silicon
dioxide film (SiO
2) to have a thickness of 0.5 µm. The lower electrode 84 and the common electrode 82
are connected electrically by a contact hole 55 formed in the insulating layer 54.
Considering piezoelectric property and dielectric breakdown voltage, the piezoelectric
body 85 is formed of lead zirconate titanate (PZT) to have a thickness of 5 µm or
less, for example. For example, the upper electrode 86 and the lower electrode 84
are formed of platinum to have a thickness of 0.15 µm. For example, the individual
electrode 81 and the common electrode 82 are formed of gold (Au) to have a thickness
of 0.3 µm.
The diaphragm 53 is formed of an insulating inorganic material. For example, the insulating
inorganic material is silicon dioxide (SiO
2). For example, the thickness of the diaphragm 53 is 2 to 10 µm and preferably 4 to
6 µm. Although illustrated below in detail, the diaphragm 53 and the protective layer
52 are bent inward when the piezoelectric body 85 applied with voltage is deformed
into a d
31 mode. Then, the diaphragm and the protective layer return to the original when the
application of voltage to the piezoelectric body 85 is stopped. The volume of the
pressure chamber (individual pressure chamber) 41 expands and contracts according
to the reversible deformation. When the volume of the pressure chamber 41 is changed,
the ink pressure in the pressure chamber 41 is changed.
For example, the protective layer 52 is formed of polyimide to have a thickness of
4 µm. The protective layer 52 covers one surface of the nozzle plate 5 on the bottom
surface side and further covers the inner peripheral surface of the hole of the nozzle
51.
FIG. 6 is a functional block diagram of the inkjet printer 10. The control board 17
as a control unit is mounted with a CPU 90, an ROM 91, and an RAM 92, an I/O port
93 which is an input/output port, and an image memory 94. The CPU 90 controls the
drive motor 24, the ink supply pressure adjusting devices 32A to 32D, the operation
unit 18, and various sensors through the I/O port 93. Print data from the computer
2 which is external connection equipment is transmitted through the I/O port 93 to
the control board 17 and is stored in the image memory 94. The CPU 90 transmits the
print data stored in the image memory 94 to the drive circuit 7 in the drawing order.
The drive circuit 7 includes a print data buffer 71, a decoder 72, and a driver 73.
The print data buffer 71 stores the print data in time series for each actuator 8.
The decoder 72 controls the driver 73 based on the print data stored in the print
data buffer 71 for each actuator 8. The driver 73 outputs the drive signal for operating
each actuator 8 based on the control of the decoder 72. The drive signal is a voltage
to be applied to each actuator 8.
Subsequently the drive waveform of the drive signal given to the actuator 8 and the
operation of ejecting ink from the nozzle 51 are described with reference to FIGS.
7 to 8E. FIG. 7 illustrates a multi drop drive waveform of dropping ink droplets three
times during one drive period by triple pulses as one example of the drive waveform.
If the ink is dropped at a high speed, the ink becomes one droplet to impact the sheet
S. The drive waveform of FIG. 7 is a so-called pulling striking of the drive waveform.
However, the drive waveform is not limited to the triple pulses. For example, the
drive waveform may be double pulses. The drive waveform is not limited to the pulling
striking and may be a pushing striking or a pushing and pulling striking.
The drive circuit 7 applies a bias voltage V1 to the actuator 8 from time t0 to time
t1. That is, the voltage V1 is applied between the upper electrode 86 and the lower
electrode 84. Then, after a voltage V0 (= 0 V) is applied until time t2 from time
t1 of starting ink ejection operation, a voltage V2 is applied from time t2 to time
t3 to perform a first ink drop. After the voltage V0 (= 0 V) is applied from time
t3 to time t4, the voltage V2 is applied from time t4 to time t5 to perform a second
ink drop. After the voltage V0 (= 0 V) is applied from time t5 to time t6, the voltage
V2 is applied from time t6 to time t7 to perform a third ink drop. If the ink is dropped
at a high speed, the ink becomes one droplet to impact the sheet S. At time t7 after
drop completion, the bias voltage V1 is applied to attenuate a vibration in the pressure
chamber 41.
The voltage V2 is a voltage smaller than the bias voltage V1. For example, the voltage
value is determined based on the attenuation rate of the pressure vibration of the
ink in the pressure chamber 41. The time from time t1 to time t2, the time from time
t2 to time t3, the time from time t3 to time t4, the time from time t4 to time t5,
the time from time t5 to time t6, and the time from time t6 to time t7 are each set
to a half period of a natural vibration period λ determined by the property of the
ink and the inner structure of the head. The half period of the natural vibration
period λ is also referred to as acoustic length (AL). During a series of operations,
the voltage of the common electrode 82 is made constant at 0 V.
FIGS. 8A to 8E schematically illustrate the operation of driving the actuator 8 with
the drive waveform of FIG. 7 to eject ink. In the standby state, the pressure chamber
41 is filled with ink. As illustrated in FIG. 8A, the meniscus position of the ink
in the nozzle 51 is stationary near zero. When the bias voltage V1 is applied as a
contraction pulse from time t0 to time t1, an electric field is generated in a thickness
direction of the piezoelectric body 85, and the deformation of the d
31 mode occurs in the piezoelectric body 85 as illustrated in FIG. 8B. Specifically,
the annular piezoelectric body 85 extends in the thickness direction and contracts
in a radial direction. Although compressive stresses are generated in the diaphragm
53 and the protective layer 52 by the deformation of the piezoelectric body 85, the
compressive force generated in the diaphragm 53 is larger than the compressive force
generated in the protective layer 52, so that the actuator 8 is bent inward. That
is, the actuator 8 is deformed to be a depression centered on the nozzle 51, and the
volume of the pressure chamber 41 is contracted.
At time t1, when the voltage V0 (= 0 V) is applied as an expansion pulse, the actuator
8 returns to a state before the deformation as schematically illustrated in FIG. 8C.
At this time, in the pressure chamber 41, the inner ink pressure is lowered due to
the return of the volume to the original state. However, ink is supplied from the
common ink chamber 42 to the pressure chamber 41 so that the ink pressure rises. Thereafter,
when the time reaches time t2, the ink supply to the pressure chamber 41 is stopped,
and the rise of the ink pressure is also stopped. That is, the state becomes a so-called
pulling state.
At time t2, as schematically illustrated in FIG. 8D, when the voltage V2 is applied
as the contraction pulse, the piezoelectric body 85 of the actuator 8 is deformed
again so that the volume of the pressure chamber 41 is contracted. As described above,
the ink pressure rises between time t1 and time t2, and further the ink pressure is
raised when the pressure chamber 41 is pushed by the actuator 8 to reduce the volume
of the pressure chamber 41, so that the ink is extruded from the nozzle 51. The application
of the voltage V2 continues to time t3, and the ink is ejected as a droplet from the
nozzle 51 as schematically illustrated in FIG. 8E. That is, the first ink drop is
performed.
When the voltage V2 is applied from time t4 to time t5 after the voltage V0 (= 0 V)
is applied from time t3 to time t4, the second ink drop is performed according to
the same operation and effect (FIGS. 8B to 8E). When the voltage V2 is applied from
time t6 to time t7 after the voltage V0 (= 0 V) is applied from time t5 to time t6,
the third ink drop is performed according to the same operation and effect (FIGS.
8B to 8E).
When the third drop is performed, at time t7, the voltage V1 is applied as a cancel
pulse. The inner ink pressure of the pressure chamber 41 is lowered by ejecting ink.
The vibration of the ink remains in the pressure chamber 41. In this regard, the actuator
8 is driven such that the voltage V2 is changed to the voltage V1 to contract the
volume of the pressure chamber 41, and the inner ink pressure of the pressure chamber
41 is made substantially zero, thereby forcibly reducing the residual vibration of
the ink in the pressure chamber 41.
Herein, the property of the pressure vibration transmitted to peripheral channels
when the actuator 8 is driven is described based on the result of the test performed
by using the ink jet head 1A in which 213 channels are arranged two-dimensionally
in the nozzle plate 5. As described above, one channel is configured by one set of
the nozzle 51 and the actuator 8. FIG. 9A illustrates channel numbers allocated to
the 213 channels arranged in an XY direction. Naturally, the channels arranged in
the Y-axis direction are obliquely arranged in practice as illustrated in FIG. 3.
In the following, right and left (X direction) sides, upper and lower (Y direction)
sides, and an oblique side are mentioned for convenience of explanation of the positional
relation between the channels.
For example, when a channel 108 which is one of the 213 channels is given attention,
and other channels are driven individually, the distribution diagram of FIG. 9B is
obtained by plotting the magnitudes of the pressures given to the attention channel
108. The channel is driven by giving a step waveform to the actuator 8. The step waveform
is a waveform for measurement which contracts the actuator 8 only once as illustrated
in FIG. 9C. A period after the contraction is set as a measurement period. The numerical
value in each cell of the distribution diagram of FIG. 9B is a maximum value of a
residual vibration amplitude induced to the attention channel 108 during the measurement
period after the drive signal is given to the driven channel. A voltage value (mV)
of the piezoelectric effect generated in the piezoelectric body 85 of the actuator
8 of the attention channel 108 is used as the value indicating the magnitude of the
residual vibration amplitude.
More specifically, the maximum value of the residual vibration amplitude is calculated
as follows. For example, the pressure waveform of FIG. 10 is obtained when the channel
109 next to the right side of the attention channel 108 is driven, and the residual
vibration which is induced to the attention channel 108 is expressed by the voltage
value (mV) of the piezoelectric effect generated in the piezoelectric body 85. At
this time, when a section of 8 µs is moved along a time axis, and a width between
a maximum value and a minimum value of the section is plotted, a waveform of "a width
of maximum and minimum values of the residual vibration" in the same drawing is obtained.
Then, the maximum value of the plotted width is plotted as the maximum value of the
residual vibration in FIG. 9B. The maximum value of "the width of maximum and minimum
values of the residual vibration" of the channel 109 is 135 mV. For the remaining
channels, the maximum value of "the width of maximum and minimum values of the residual
vibration" is measured by the same procedure.
From the result of FIG. 9B, it is understood that the effect of the vibration to the
attention channel 108 from the channels 109 and 108 adjacent to the upper and lower
sides of the attention channel 108 is the largest. It is understood that the effect
of the vibration from the channels 100 and 116 adjacent to the right and left sides
is the next largest. That is, in order that the effect from the peripheral channels
is reduced such that the channel performs a stable ejection, particularly, the effect
of the vibration from the channels on the upper and lower sides and the right and
left sides is desirably reduced as much as possible.
Subsequently, the distribution diagram of FIG. 11 is obtained when the magnitude of
the pressure given to the attention channel 108 is plotted. The numerical value in
each cell of the distribution diagram of FIG. 11 indicates the magnitude of the pressure
generated in the attention channel 108 when ten seconds elapse after the drive signal
is given to the channel. A positive value indicates a positive pressure, and a negative
value indicates a negative pressure. A voltage value (mV) of the piezoelectric effect
generated in the piezoelectric body 85 of the actuator 8 of the attention channel
108 is measured as the value indicating the magnitude of the pressure.
As illustrated in the distribution diagram of FIG. 11, the channels surrounding the
attention channel 108 generate pressure at almost the same phase as each other (the
range of the positive value), and further the channels surrounding the outer periphery
thereof reversely generate pressure at the almost reverse phases (the range of the
negative value). That is, a distance from the attention channel 108 to the area of
the channel group which generates the reverse-phase pressure corresponds to a half
wavelength of the pressure vibration which is transmitted while spreading along the
surface of the nozzle plate 5. That is, the half wavelength of the pressure vibration
which is transmitted while spreading along the surface of the nozzle plate 5 is longer
than a pitch (adjacent distance) of the channels arranged in the nozzle plate 5 in
a surface direction. For this reason, the pressure vibrations of the channels, which
have a positional relation of being close to each other, such as adjacent channels
are in phase.
The waveform diagram of FIG. 12 illustrates the respective pressure waveforms (residual
vibration waveform) appearing in the attention channel 108 when a channel 116 and
a channel 132 are driven individually. The channel 116 is next to the right side of
the attention channel 108. The channel 132 is positioned at the third right position
from the attention channel 108. In the pressure waveform (residual vibration waveform),
a vertical axis indicates the voltage value (mV) of the piezoelectric effect representing
the magnitude of the pressure, and a horizontal axis indicates time (µs). The natural
pressure vibration period λ of the ink jet head 1A is 4 µs, and the half period (AL)
thereof is 2 µs. From the result, it is understood that the pressure given to the
attention channel 108 varies in the magnitude and the phase depending on the places
of the driven channels.
On the other hand, the waveform diagram of FIG. 13 illustrates the respective pressure
waveforms (residual vibration waveform) appearing in the attention channel 108 when
a channel 109 and a channel 107 are driven individually. The channel 109 is next to
the upper side of the attention channel 108. The channel 107 is next to the lower
side of the attention channel. From the result, it is understood that the pressure
waveforms which the channels next to the upper side and the lower side of the attention
channel give to the attention channel are similar.
The waveform diagram of FIG. 14 illustrates the respective pressure waveforms (residual
vibration waveform) appearing in the attention channel 108 when a channel 100 and
the channel 116 are driven individually. The channel 100 is next to the left side
of the attention channel 108. The channel 116 is next to the right side of the attention
channel 108. From the result, it is understood that the pressure waveforms which the
channels next to the left side and the right side of the attention channel give to
the attention channel are almost identical.
The waveform diagram of FIG. 15 illustrates the respective pressure waveforms (residual
vibration waveform) appearing in the attention channel 108 when a channel 101 and
a channel 99 are driven individually. The channel 101 is next to the upper left side
of the attention channel 108. The channel 99 is next to the lower left side of the
attention channel 108. From the result, it is understood that the pressure waveforms
which the channels next to the obliquely upper left side and the obliquely lower left
side of the attention channel give to the attention channel are also similar. The
waveform diagram of FIG. 16 illustrates the respective pressure waveforms (residual
vibration waveform) appearing in the attention channel 108 when a channel 117 and
a channel 115 are driven individually. The channel 117 is next to the upper right
side of the attention channel 108. The channel 115 is next to the lower right side
of the attention channel 108. From the result, it is understood that the pressure
waveforms which the channels next to the obliquely upper right side and the obliquely
lower right side of the attention channel give to the attention channel are also similar.
From the results illustrated in FIGS. 11 to 16, it is understood that the channels
which are positioned to be symmetrical to the attention channel give almost the same
pressure vibration to the attention channel. That is, the channels adjacent to the
right and left sides (X direction) of the attention channel, the channels adjacent
to the upper and lower sides (Y direction) of the attention channel, and the channels
adjacent to the obliquely upper and obliquely lower sides of the attention channel
are each positioned to be symmetrical to the attention channel and each give almost
the same pressure vibration to the attention channel.
Based on the above results, four drive timings A1, A2, B1, and B2 in which time differences
(delay time) are set between the drive waveforms given to the plural actuators 8 are
prepared as one example is illustrated in FIG. 17. The drive waveform of a group A
configured by the drive timings A1 and A2 and the drive waveform of a group B configured
by the drive timings B1 and B2 are shifted to each other by a half of the drive period.
One drive period is configured by a time tAB of performing the ejection operation
of a former half portion and a time tBA of the standby until the next ejection operation
is started. As one example, if each pulse of the drive waveform from time t1 to time
t7 is set to the half period AL of the natural vibration period λ, and the drive period
of the ink jet head is 24 µs, the time tAB of the ejection operation is 12 µs. Preferably,
the time tAB of the ejection operation and the time tBA of the standby are the same
time or almost the same time.
Even in the drive waveforms of the group A, the drive waveform of the drive timing
A1 and the drive waveform of the drive timing A2 are shifted by the half period AL
(a half of λ) of the natural pressure vibration period λ. Similarly, even in the drive
waveforms of the group B, the drive waveform of the drive timing B1 and the drive
waveform of the drive timing B2 are shifted by the half period AL (a half of λ) of
the natural pressure vibration period λ. However, the drive waveforms may have phases
reverse to each other, and the shifted time (delay time) is not limited to the half
period (1AL). The shifted time may be odd times the half period AL.
As one example is illustrated in FIG. 18, the drive timings A1, A2, B1, and B2 are
regularly allocated to all the 213 channels, to form a checkered pattern. That is,
the drive timing (B1 or B2) of the group B is allocated to all the channels adjacent
to the upper and lower sides and the right and left sides of the channel to which
the drive timing (A1 or A2) of the group A is allocated. Conversely, the drive timing
(A1 or A2) of the group A is allocated to all the channels adjacent to the upper and
lower sides and the right and left sides of the channel to which the drive timing
(B1 or B2) of the group B is allocated. In the channel at a corner, naturally, the
channels adjacent to one side of upper and lower sides and one side of the right and
left sides become targets.
In the channels adjacent to the upper and lower sides of the channel to which the
drive timing (A1 or A2) of the group A is allocated, the drive timing B1 is allocated
to one channel, and the drive timing B2 is allocated to the other channel. In the
channels adjacent to the right and left sides, the drive timing B1 is allocated to
one side, and the drive timing B2 is allocated to the other side. That is, the channels
adjacent to the upper and lower sides and the channels adjacent to the right and left
sides each are a pair of channels which are driven by the drive waveforms with reverse
phases.
Similarly, in the channels adjacent to the upper and lower side of the channel to
which the drive timing (B1 or B2) of the group B is allocated, the drive timing A1
is allocated to one channel, and the drive timing A2 is allocated to the other channel.
In the channels adjacent to the right and left sides, the drive timing A1 is allocated
to one channel, and the drive timing A2 is allocated to the other channel. That is,
the channels adjacent to the upper and lower sides and the channels adjacent to the
right and left sides each are a pair of channels which are driven by the drive waveforms
with reverse phases.
That is, in the 213 channels of FIG. 18, even when any channel is given attention,
the drive period between the channels adjacent to the upper and lower sides of the
channel and the drive period between the channels adjacent to the right and left sides
of the channel are shifted by a half.
If the drive period is short, the printing speed is fast. The drive period is determined
from the printing speed required for a printer. When the drive period is a predetermined
value, tAB is set to be equal to tBA, such that any channel is driven at the timing
separated as far as possible from the drive timings of the channels adjacent to the
upper and lower sides and the right and left sides. Accordingly, it is possible to
reduce the crosstalk from the channels which are adjacent to the upper and lower sides
and the right and left sides and to which the channel is most susceptible. The channels
adjacent to the upper and lower sides and the channels adjacent to the right and left
sides each are a pair of channels which are driven by the drive waveforms with phases
reverse to each other. Thus, the effects of the pressures on the channel positioned
at the center thereof are canceled by each other. That is, as described above, the
channels adjacent to the upper and lower sides and the right and left sides are channels
which are positioned to be symmetrical to the attention channel. The channels which
are positioned symmetrically give the pressure vibration with almost the same or similar
waveforms to the attention channel. Therefore, when both channels are driven at the
same timing (in-phase), the vibrations are added to each other to amplify the pressure
vibration, which is given to the attention channel. However, when the drive timings
are shifted by the half period, and the channels are driven in the drive waveforms
with reverse phases, the pressure vibrations with the reverse phases in which the
vibrations are canceled by each other are given to the attention channel.
The drive waveforms illustrated in FIGS. 7 and 17 are multi-drop waveforms of ejecting
three small drops while forming one dot. In the multi-drop waveforms illustrated in
FIGS. 7 and 17, the ejections of the small drops are performed at times t2, t4, and
t6 with the timing when the voltage V2 is given to the actuator as a starting point.
The time from time t1 to time t2, the time from time t2 to time t3, the time from
time t3 to time t4, the time from time t4 to time t5, the time from time t5 to time
t6, and the time from time t6 to time t7 are each set to the half period (AL) of the
natural vibration period λ. The drive timing A2 is delayed by the half period (AL)
from the drive timing A1. The drive timing B2 is delayed by the half period (AL) from
the drive timing B1. Therefore, the drive timing A1 and the drive timing A2 of the
multi-drop waveform are driven at the reverse phases whenever small drops are ejected.
The drive timing B1 and the drive timing B2 of the multi-drop waveform are driven
at the reverse phases whenever small drops are ejected. For this reason, in the multi-drop
waveform, the crosstalk is reduced more effectively. Naturally, the multi-drop waveform
is not limited to the multi-drop waveform which ejects three small drops while forming
one dot. For example, a multi-drop waveform may be used which ejects two or four small
drops while forming one dot. The effect of reducing the above-described crosstalk
can be obtained although the drive waveform is not necessarily a multi-drop waveform.
That is, the drive waveform is not limited to the multi-drop waveform.
When the checkered pattern is allocated as illustrated in FIG. 18, in the channel
adjacent to any one of the right and left sides of the attention channel and the channel
adjacent to any one of the upper and lower sides, a pair of channels are driven by
drive waveforms with the reverse phases or are driven by in-phase drive waveforms.
Even in this case, in the pair of channels driven by the drive waveforms with the
reverse phases, the pressure vibrations of the reverse phases in which the vibrations
are canceled by each other are given to the attention channel. The channels next to
the obliquely upper left side, the obliquely lower left side, the obliquely upper
right side, and the obliquely lower right side have the same drive period as the attention
channel and have the group A of the drive timings. However, the channels next to the
obliquely upper left side and the obliquely lower left side and the channels next
to the obliquely upper right side and the obliquely lower right are each driven by
the drive waveforms with phase reverse to each other, and thus the pressure vibrations
with the reverse phases in which the vibrations are canceled by each other are given
to the attention channel.
FIG. 18 is one example of the drive timings A1, A2, B1, and B2 allocated to the 213
channels. However, even if the number of the channels is 213 or more, the stable ejection
can be performed by allocating the drive timings A1, A2, B1, and B2 with the same
regularity.
Second Embodiment
[0020] Subsequently, the liquid ejection device 1 of a second embodiment will be described.
FIG. 19 is a nozzle arrangement when the sheet S is viewed from the Z-axis direction
in FIG. 1 through the ink jet head 1A which is one example of the liquid ejection
device 1. That is, FIG. 19 is a projection plan view of the nozzle arrangement. The
reference numerals #1 to #66 in the drawings indicate the channel numbers corresponding
to those of FIG. 9A, and the nozzles 51 subsequent to the channel number 66 are not
illustrated for convenience. The configuration of the actuator 8 or the like is the
same as in the ink jet head 1A of the first embodiment except for the nozzle arrangement.
Therefore, the description is not given in detail.
As illustrated in FIG. 19, the nozzles 51 arranged in the column direction (X direction)
are arranged alternately to be separated by a predetermined distance in the Y-axis
direction. For example, in column 1, a nozzle 51 group of #1, #17, #33, #49, and #65
are separated by a predetermined distance in the Y-axis direction from a nozzle 51
group of #9, #25, #41, and #57. That is, the nozzles are arranged with a relative
shift in the Y-axis direction. When a distance X1 between the nozzles is defined as
"1 p", the distance of the relative shift in the Y-axis direction is 0.5 p. When all
the nozzle 51 from columns 1 to 8 are set as targets and viewed from the Y direction,
the distance X1 between the nozzles is a nozzle pitch in the X direction. The pitch
of the nozzles 51 in the X direction in the same column is 8 p. Similarly, the nozzles
51 arranged in columns 2 to 8 in the column direction (X direction) are shifted alternately
in the Y-axis direction. However, the rows of the nozzles 51 shifted in the Y-axis
direction are formed to alternate with those of the upper and lower columns. Thus,
the checkered pattern is formed by the nozzles 51 shifted in the Y-axis direction
and the nozzles 51 not shifted.
In the arrangement of the checkered pattern as above, for example, if the nozzle 51
of #14 is given attention, the nozzle 51 of #22 adjacent in the X direction and the
nozzle 51 of #6 adjacent in the -X direction are separated by a distance of 0.5 p
in the Y-axis direction from the nozzle 51 of #14 given attention. In the nozzle 51
of #15 adjacent in the Y direction, the separation distance from the nozzle 51 of
#14 given attention in the Y-axis direction is 6.5 p. In the nozzle 51 of #13 adjacent
in the -Y direction, the separation distance from the nozzle 51 of #14 given attention
in the Y-axis direction is 5.5 p. That is, when any one of a plurality of nozzles
51 is given attention, the nozzle 51 given attention and the nozzles 51 adjacent in
the X direction and the -X direction are arranged to be relatively shifted by the
distance of 0.5 p in the Y-axis direction. The nozzle 51 may be arranged such that
when the separation distance of the nozzles 51 adjacent in the Y direction and the
-Y direction from the nozzle 51 given attention in the Y-axis direction is 6.5 p for
one nozzle 51, the separation distance is 5.5 p for the other nozzle 51. In the nozzle
51 itself given attention, the nozzle is arranged to be relatively shifted by the
distance of 0.5 p in the Y-axis direction from the nozzles 51 adjacent to the upper
and lower sides and the right and left sides in the X direction, the -X direction,
the Y direction, and the -Y direction.
The nozzles 51 adjacent in the X direction, the nozzles 51 adjacent in the Y direction,
the shift distance in the Y-axis direction, and the separation distance in the Y-axis
direction satisfy the positional relation and the distance of the nozzles 51 illustrated
in FIG. 20. That is, the nozzles 51 adjacent in the X direction are the nozzles 51
adjacent in the same column and are not necessarily on the X axis. The same is applied
to the case of the -X direction. The nozzles 51 adjacent in the Y direction are the
nozzles 51 arranged obliquely and adjacent on the same row and are not necessarily
on the Y axis. The same is applied to the case of the -Y direction. The shift distance
of the Y-axis direction and the separation distance of the Y-axis direction are the
separation distance on the Y axis. The Y axis is a direction of a relative movement
of the ink jet head 1A and the sheet S when the image or the like is printed on the
sheet S.
p indicates a dot pitch of the dot which is formed on the sheet S when the ink jet
head 1A ejects ink. In the case of the ink jet head 1A of 600 DPI, it is satisfied
that p ≅ 42.25 µm. Accordingly, it is satisfied that 0.5 p ≅ 21.13 µm, 5.5 p ≅ 232.38
µm, and 6.5 p ≅ 274.63 µm. If the shift of 0.5 p is not provided, all the separation
distances of the nozzles 51 adjacent in the Y direction in the Y-axis direction are
6 p (≅ 253.5 µm). p may be defined not to be associated with the dot pitch and, for
example, may be defined by the nozzle pitch (= X1) in the X direction.
0.5 p, 5.5 p, and 6.5 p are repsective examples of the set distance. The distance
by which the nozzles 51 adjacent in the X direction and the -X direction are shifted
in the Y-axis direction is not limited to 0.5 p and may be set according to Expression
(m + 0.5)p. The character m is a natural number including 0. The separation distances
of the nozzles 51 adjacent in the Y direction and the -Y direction in the Y-axis direction
are not limited to 6.5 p and 5.5 p and may be set according to Expression (n + 0.5)p
and Expression (n - 0.5)p. n is a natural number not including 0. That is, any set
distance is odd times a half of P.
As described above, Y in FIG. 19 is a direction of the relative movement of the ink
jet head 1A and the sheet S when an image or the like is printed on the sheet S. For
example, if the sheet S is directed to the lower side of the ink jet head 1A from
the -Y direction, the nozzles 51 facing the sheet S first are the nozzles 51 of #10,
#26, #42, and #58 of column 8, and after the delay of the time required for sheet
conveyance of the distance of 0.5 p, the nozzles 51 of #2, #18, #34, #50, and #66
of the same column face the sheet S. When facing the sheet S, the nozzles 51 are positioned
in a printing range of the sheet S.
Thereafter, after the delay of the time required for the sheet conveyance of the distance
of 5.5 p, the nozzles 51 of #3, #19, #35, and #51 arranged in column 7 face the sheet
S, and after the delay of the time required for the sheet conveyance of the distance
of 0.5 p, the nozzles 51 of #11, #27, #43, and #59 of the same column face the sheet
S.
Thereafter, after the delay of the time required for the sheet conveyance of the distance
of 6.5 p, the nozzles 51 of #12, #28, #44, and #60 arranged in column 6 face the sheet
S, and after the delay of the time required for the sheet conveyance of the distance
of 0.5 p, the nozzles 51 of #4, #20, #36, and #52 of the same column face the sheet
S.
If the drive timings illustrated in FIG. 18 are set for respective channels, in the
nozzles 51 of #9, #16, #41, #48, ..., #19, #26, #51, and #58, the actuators 8 are
driven at the drive timing of A1. In the nozzles 51 of #25, #32, #57, #64, ..., #3,
#10, #35, and #42, the actuators 8 are driven at the drive timing of A2. In the nozzles
51 of #8, #33, #40, #65, ..., #11, #18, #32, and #50, the actuators 8 are driven at
the drive timing of B1. In the nozzles 51 of #17, #24, #49, #56, ..., #2, #27, #34,
#59, and #66, the actuators 8 are driven at the drive timing of B2.
As for the nozzle 51 of #14 which is previously given attention, the actuator 8 of
the nozzle 51 of #14 is driven at the drive timing of A2 in the group A (A1 and A2).
All the actuators 8 of the nozzles 51 of #6 and #22 adjacent on the right and left
sides in the X direction and the -X direction and the nozzles 51 of #13 and #15 adjacent
on the upper and lower sides in the Y direction and the -Y direction are driven at
the drive timing of the group B (B1 and B2) which is shifted by a half of the drive
period from that of the nozzle 51 of #14. During the execution of printing, the nozzles
51 having the drive timings of the group A are driven, and then after the delay of
the time of a half of the drive period, the nozzles 51 having the drive timings of
the group B are driven. However, the nozzles 51 having the drive timings of the group
B face the sheet S after the delay of 0.5 p from the nozzles 51 having the drive timings
of the group A. Thus, although the nozzles are driven at the timing delayed by a half
of the drive period, the printing results of the group A and the group B are arranged
on one straight line on the sheet S.
The time difference of the drive timings of B1 and B2 and the time difference of the
drive timings of A1 and A2 are slight and thus do not affect linearity. Although there
is an effect, the effect is extremely small.
The direction of the relative movement of the ink jet head 1A and the sheet S may
be a single-pass type in which the ink jet head 1A is fixed, and the sheet S moves
in one direction of the Y-axis direction. However, for example, a scan type may be
adopted in which the ink jet head 1A and the sheet S move relatively in the X-axis
direction. In the case of the scan type, the direction in which the ink jet head 1A
moves during the printing operation is set to X. Thus, similarly to the previous one,
the nozzles 51 of #10, #26, #42, and #58 of column 8 first face the sheet S, and after
the delay of the time required for the head movement of the distance of 0.5 p, the
nozzles 51 of #2, #18, #34, #50, and #66 of the same column face the sheet S.
As described above, in the second embodiment, in the nozzle 51 of the drive timing
of the group B, the actuator 8 is driven at the timing delayed by a half of the drive
period from that of the nozzle 51 of the drive timing of the group A. That is, the
channel is driven at the timing separated as far as possible from the drive timings
of the channels adjacent to the upper and lower sides and the right and left sides.
Thus, it is possible to reduce the crosstalks from the channels which are adjacent
to the upper and lower sides and the right and left sides and to which the channel
is most susceptible. When the position of the nozzle 51 is shifted by odd times a
half of the dot pitch or the nozzle pitch in a feed direction (Y-axis direction) of
the sheet S, the linearity of the printing result can be maintained although the channel
is driven at the timing delayed by a half of the drive period.
Hereinbefore, the configuration in which the nozzle arrangement is associated with
the drive timing is described as one preferable example. However, the association
with the delay timing is not necessary.
Third Embodiment
[0021] Subsequently, a liquid ejection device of a third embodiment will be described. FIG.
21 illustrates a longitudinal sectional view of the ink jet head 101A as one example
of the liquid ejection device. The ink jet head 101A is configured to be the same
as the ink jet head 1A illustrated in the first embodiment except that the pressure
chamber (individual pressure chamber) 41 is not provided, and the nozzle plate 5 communicates
directly with the common ink chamber 42. Accordingly, the same configurations as the
ink jet head 1A are denoted by the same reference numerals, and the detail description
is not given.
Also in the ink jet head 101A illustrated in FIG. 21, all the channels are driven
such that the drive timings A1, A2, B1, and B2 of the checkered pattern are allocated
as one example is illustrated in FIG. 18.
According to any one embodiment described above, the drive timings A1, A2, B1, and
B2 of the checkered pattern are allocated as one example is illustrated in FIG. 18.
Thus, even when any channel is given attention, the drive periods of the channels
adjacent to the upper and lower sides and the right and left sides are shifted by
a half. Thus, when the ejection operation is performed on the channel at the center,
the channel is hardly affected by the pressure vibration from the channels adjacent
to the upper and lower sides and the right and left sides. As a result, the crosstalk
in which the operations of the actuators interfere with each other can be prevented,
and liquid can be ejected stably.
That is, in the ink jet heads 1A and 101A, the actuator 8 and the nozzle 51 are arranged
on the surface of the nozzle plate 5. In this case, when the plurality of actuators
8 are driven simultaneously, the surface of the nozzle plate 5 is bent, and the crosstalk
in which the operation of the actuator 8 interferes with the operation of another
actuator 8 occurs due to the reason that the pressure change from the peripheral actuators
8 has an effect through the common ink chamber 42. In this regard, when the drive
timings are allocated as described above, the crosstalks from the peripheral actuators
8 is prevented.
In the above-described embodiments, the actuators of the nozzles adjacent to the right
and left sides, the actuators of the nozzles adjacent to the upper and lower sides,
and the actuators of the nozzle adjacent to any one of the right and left sides and
the nozzle adjacent to any one of the upper and lower sides are each driven by the
drive waveforms with phases reverse to each other. However, any one may be driven
as above, and all the actuators do not necessarily satisfy all conditions.
In the above-described embodiment, the ink jet heads 1A and 101A of the inkjet printer
1 are described as one example of the liquid ejection device. However, the liquid
ejection device may be a shaping-material ejection head of a 3D printer and a sample
ejection head of a dispensing device.
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 scope of the inventions.
The accompanying claims and their equivalents are intended to cover such forms or
modifications as would fall within the scope of the inventions.