JP2022135692A - Droplet ejection head, its drive circuit, and printer - Google Patents

Abstract

An object of the present invention is to easily change a drive pattern to be applied for ejection of a discharge amount that can be realized by a plurality of drive patterns. According to one embodiment, a drive circuit includes a generator, a selector, and a controller. The generation unit generates a plurality of drive signals in parallel for deforming the actuator in a plurality of patterns, some of the plurality of patterns are different patterns for realizing a plurality of stages of discharge amounts, and some of the plurality of patterns are a plurality of stages. A plurality of different patterns are used to realize a part of the ejection amount of . The selector selects and supplies one of the drive signals generated by the generator to each of the actuators. The control unit supplies drive signals associated with the received data to the plurality of actuators based on a lookup table representing which of the plurality of drive signals should be supplied to each of the plurality of actuators in association with each of the data. to control the selector. [Selection drawing] Fig. 16

Description

Embodiments of the present invention relate to a droplet ejection head, its drive circuit, and a printer.

A droplet ejection head is known as, for example, an inkjet head. In a droplet ejection head that ejects droplets by changing the volume of one pressure chamber by deforming each of a plurality of actuators, the same ejection amount may be achieved by a plurality of drive patterns.
In the case of such a droplet discharge head, which drive pattern is applied to discharge a discharge amount that can be realized by a plurality of drive patterns is selected at the stage of designing the drive circuit or the droplet discharge head. rice field.
Therefore, it has been difficult to change the drive pattern used for ejection of a certain ejection amount.
Under these circumstances, it has been desired to be able to easily change the drive pattern to be applied to achieve a discharge amount that can be achieved by a plurality of drive patterns.

JP-A-7-60961

SUMMARY OF THE INVENTION An object of the present invention is to provide a droplet discharge head, a drive circuit for the droplet discharge head, and a printer capable of easily changing the drive pattern to be applied to discharge a discharge volume that can be realized by a plurality of drive patterns. .

A drive circuit according to an embodiment includes a plurality of actuators that change the volume of a pressure chamber by deforming according to a supplied drive signal, and discharges liquid from the pressure chamber according to the change in the volume of the pressure chamber. A liquid that can change the discharge amount at one time into a plurality of stages by combining the respective deformation patterns of the actuator, and can be realized by any combination of the plurality of deformation patterns for at least a part of the plurality of stages. A generator, a selector, and a controller are provided to drive the ejection head. The generating unit generates a plurality of driving signals in parallel for deforming the actuator in a plurality of patterns, and some of the plurality of patterns are a plurality of different driving signals for realizing respective discharge amounts in a plurality of stages. A plurality of patterns are used, and a part of the plurality of patterns is a plurality of different patterns that achieve a part of the discharge amount in a plurality of stages. The selection unit selects and supplies one of the plurality of drive signals generated by the generation unit to each of the plurality of actuators. When receiving any one of a plurality of data representing different discharge amounts, the control unit indicates which of the plurality of drive signals should be supplied to each of the plurality of actuators in association with each of the plurality of data. Based on the lookup table obtained, the selector is controlled so as to supply drive signals associated with the received data to the plurality of actuators.

FIG. 2 is a block diagram showing the main circuit configuration of the printer according to one embodiment; FIG. 2 is a diagram showing the main configuration of the inkjet head shown in FIG. 1; 2 is an exploded perspective view showing a part of the inkjet head shown in FIG. 1; FIG. 3A and 3B are diagrams showing the operation of an actuator formed by the protrusions and electrodes of the piezoelectric member shown in FIG. 2; FIG. FIG. 4 is a diagram showing a first drive pattern; The figure which shows a 2nd drive pattern. The figure which shows a 3rd drive pattern. The figure which shows a 4th drive pattern. The figure which shows the 5th drive pattern. The figure which shows the 6th drive pattern. The figure which shows the 7th drive pattern. The figure which shows the 8th drive pattern. The figure which shows the 9th drive pattern. The figure which shows the 10th drive pattern. FIG. 4 is a diagram showing six types of waveforms of a first drive signal and a second drive signal; FIG. 4 is a diagram schematically showing contents of a lookup table;

A liquid droplet ejection device as an example of an embodiment will be described below with reference to the drawings. In the following, an example of realizing a droplet ejection device as a printer suitable for printing an image by spraying ink droplets onto a sheet of paper (recording medium) will be described.

FIG. 1 is a block diagram showing the essential circuitry of a printer 100 according to this embodiment.
As shown in FIG. 1, the printer 100 includes a processor 101, a main memory 102, an auxiliary storage unit 103, an operation panel 104, a communication interface 105, a transport unit 106, a transport control unit 107, a supply unit 108, a supply control unit 109, an inkjet A head 110 and a transmission line 111 are included.

By connecting the processor 101 , the main memory 102 and the auxiliary storage unit 103 via a transmission line 111 , a computer that performs information processing for controlling the printer 100 is configured.
The processor 101 corresponds to the core part of the computer. The processor 101 executes the above information processing according to information processing programs such as an operating system, middleware, and application programs.

The main memory 102 corresponds to the main memory portion of the computer. Main memory 102 includes a non-volatile memory area and a volatile memory area. The main memory 102 stores an information processing program in a nonvolatile memory area. The main memory 102 may also store data necessary for the processor 101 to execute processing for controlling each unit in a non-volatile or volatile memory area. The main memory 102 uses a volatile memory area as a work area in which data is appropriately rewritten by the processor 101 .

The auxiliary storage unit 103 corresponds to the auxiliary storage portion of the computer. As the auxiliary memory unit 103, well-known memory devices such as electric erasable programmable read-only memory (EEPROM), hard disc drive (HDD) and solid state drive (SSD) can be used alone or in combination. Auxiliary storage unit 103 stores data used by processor 101 in performing various types of processing and data generated by processing in processor 101 . Auxiliary storage unit 103 stores an information processing program.

Operation panel 104 includes an input device and a display device. The operation panel 104 inputs instructions from an operator using an input device. The operation panel 104 displays various information to be notified to the operator using a display device. A touch panel, for example, can be used as the operation panel 104 . However, various other devices can be appropriately used as the input device and the display device.

The communication interface 105 transmits and receives data to and from an external device via a communication network such as a LAN (local area network). The external device is, for example, an information processing device that requests the printer 100 to print. A known device such as a LAN communication device can be used as the communication interface 105 .

The transport unit 106 includes a motor, gears, rollers, and the like, and transports the paper across the flight path of the ink droplets ejected from the inkjet head 110 . Note that the transport unit 106 may move the inkjet head 110 along the fixed paper surface. Further, the transport unit 106 may move both the inkjet head 110 and the paper such that the inkjet head 110 moves along the surface of the paper. In other words, the transport unit 106 is an example of a moving unit as long as it moves the inkjet head 110 and the paper so as to change the relative positional relationship between the two.
Under the control of the processor 101 , the transport control unit 107 controls the transport unit 106 so that the paper is transported at a predetermined timing synchronized with the ejection operation of the ink droplets by the inkjet head 110 .

The supply unit 108 includes, for example, ink tanks, pumps, pipes and valves, and supplies ink to the inkjet head 110 . When the inkjet head 110 is of a circulation type, the supply unit 108 can also collect ink from the inkjet head 110 that has not been ejected.
A supply control unit 109 controls the supply unit 108 under control by the processor 101 .

The inkjet head 110 ejects the ink supplied by the supply unit 108 as ink droplets based on the line data. An ink droplet is an example of a droplet, and the inkjet head 110 is an example of a droplet ejection head.
The transmission line 111 includes an address bus, a data bus, a control signal line, etc., and transmits data and control signals exchanged between the connected units.

FIG. 2 is a diagram showing the configuration of the main part of the inkjet head 110. As shown in FIG. FIG. 3 is a perspective view showing a part of the inkjet head 110 exploded. 2 and 3, the up-down direction and the left-right direction in FIG. The front side in FIG. 2 and the upper left side in FIG. 3 are called the rear end side. The back side in FIG. 2 and the lower right side in FIG. 3 are called the tip side.

The inkjet head 110 includes a substrate 1, a piezoelectric unit 2, electrodes 3, 4, 5, a top plate 6, a nozzle plate 7 and a drive IC8.
The substrate 1 is an elongated plate-like member whose longitudinal direction is the width direction. It is desirable that the substrate 1 have a small dielectric constant. It is desirable that the substrate 1 has a small difference in thermal expansion coefficient from the piezoelectric unit 2 . Suitable materials for substrate 1 are, for example, alumina (Al ₂ O ₃ ), silicon nitride (Si ₃ N ₄ ), silicon carbide (SiC), aluminum nitride (AlN) or lead zirconate titanate (PZT).

A piezoelectric unit 2 is bonded to the upper surface of the substrate 1 . The piezoelectric unit 2 includes a first piezoelectric member 21 and a second piezoelectric member 22 . The material of the first piezoelectric member 21 and the second piezoelectric member 22 is, for example, lead zirconate titanate (PZT), lithium niobate (LiNbO ₃ ), lithium tantalate (LiTaO ₃ ), or the like. A first piezoelectric member 21 is bonded to the upper surface of the substrate 1 . A second piezoelectric member 22 is bonded onto the first piezoelectric member 21 . The first piezoelectric member 21 and the second piezoelectric member 22 are polarized in directions opposite to each other with respect to their joint surfaces.
The piezoelectric unit 2 has a plurality of plate-shaped projections PRA and PRB extending in the vertical direction and arranged in parallel along the width direction. The bonding surfaces of the first piezoelectric member 21 and the second piezoelectric member 22 are located near the center in the vertical direction of each of the plurality of protrusions PRA and PRB. The protrusions PRA and PRB have similar shapes and are arranged alternately. The distance between the right side surface of the protrusion PRA in FIG. 2 and the left side surface of the protrusion PRB in FIG. less than the spacing to the right flank of the That is, the intervals between the protrusions PRA and PRB are alternately different. However, the distance between protrusions PRA and PRB is not limited to this relationship. The space between the right side surface of the protrusion PRA in FIG. 2 and the left side surface of the protrusion PRB in FIG. This results in a pressure chamber CHA. The space between the left side surface of the protrusion PRA in FIG. 2 and the right side surface of the protrusion PRB in FIG. This results in an air chamber CHB. The piezoelectric unit 2 closes the rear end sides of the pressure chamber CHA and the air chamber CHB.

The electrode 3 is a conductive film covering the side surface of the protrusion PRA facing the air chamber CHB. The electrode 4 is a conductive film covering the side surface of the protrusion PRB facing the air chamber CHB. The electrode 5 is a conductive film that covers the side surface of the projection PRA facing the pressure chamber CHA and the side surface of the projection PRB facing the pressure chamber CHA, and is connected to the pressure chamber CHA at the bottom surface thereof. The electrodes 3, 4 and 5 have a two-layer structure of nickel (Ni) and gold (Au), for example. The electrodes 3, 4, 5 are formed uniformly by plating, for example. The method of forming the electrodes 3, 4, 5 is not limited to the plating method, and may be a sputtering method, a vapor deposition method, or the like. Note that the thicknesses of the electrodes 3, 4, and 5 are exaggerated in FIG. The electrode 4 is grounded via a conductive path formed by a conductive pattern, wire, or the like.

The top plate 6 is an elongated plate-like member whose longitudinal direction is the width direction. The top plate 6 is joined to the upper surface of the piezoelectric unit 2 and closes the upper portions of the pressure chamber CHA and the air chamber CHB.
The nozzle plate 7 is joined to the end face of the piezoelectric unit 2 on the tip side, and closes the tip sides of the pressure chamber CHA and the air chamber CHB. A plurality of nozzles 71 are formed in the nozzle plate 7 so as to correspond to each of the plurality of pressure chambers CHA. The nozzle 71 connects one corresponding pressure chamber CHA among the plurality of pressure chambers CHA and the outside of the inkjet head 110 . The nozzle 71 has a constricted portion slightly on the tip side of the center and gradually widens from there toward both the tip side and the rear end side. Note that the nozzle 71 is not limited to this shape. For example, it may have a tapered truncated cone shape in which the diameter of the nozzle on the ejection surface side becomes smaller. The plurality of nozzles 71 are arranged in a row along the width direction.
A structure including the substrate 1, the piezoelectric unit 2, the electrodes 3, 4, 5, the top plate 6, and the nozzle plate 7 as described above is hereinafter referred to as a head main body.

The drive IC 8 drives the head body so as to cause ink ejection from the nozzles 71 .
The drive IC 8 includes a pixel separator 81, a waveform generator 82 and a plurality of drivers 83, as shown in FIG.

Line data is input to the pixel separator 81 . Line data is a set of pixel data representing respective gradation values of a plurality of pixels included in one line. The pixel separator 81 outputs the pixel data included in the line data in parallel to each of the plurality of driving units 83 .
A waveform generator 82 simultaneously generates a plurality of drive signals having different waveforms and outputs the plurality of drive signals in parallel.

The number of drive units 83 is the same as the number of pressure chambers CHA provided in the head body. The plurality of drive units 83 are paired with each of the plurality of pressure chambers CHA. The drive unit 83 supplies a drive signal to each of the electrodes 3 and 4 provided on the projections PRA and PRB sandwiching the pair of pressure chambers CHA.
The drive unit 83 includes selectors 831 and 832, amplifiers 833 and 834, and an LUT converter 835, as shown in FIG. Although FIG. 2 shows only the configuration of one drive section 83, the other drive sections 83 have the same configuration.

A plurality of drive signals output from the waveform generator 82 are input in parallel to the selectors 831 and 832 . The selector 831 selects and outputs one drive signal to be supplied to the electrode 3 from among the plurality of drive signals under the control of the LUT converter 835 . The selector 832 selects and outputs one drive signal to be supplied to the electrode 4 from among the plurality of drive signals. The amplifier 833 amplifies the drive signal output from the selector 831 to a signal level for causing a desired deformation in the protrusion PRA to which the electrode 3 to which it is supplied is attached.
The amplifier 834 amplifies the drive signal output from the selector 832 to a signal level for causing a desired deformation in the protrusion PRB to which the electrode 4 to which it is supplied is attached. Drive signals output from the amplifiers 833 and 834 are supplied to the electrodes 3 and 4 via individual conductive paths formed by conductive patterns and wires.
The LUT converter 835 controls the selectors 831 and 832 so as to cause ink discharge according to the gradation value represented by the pixel data supplied from the pixel separator 81 . The LUT converter 835 incorporates a memory 8351 that stores lookup tables in an updatable manner. The memory 8351 is an example of a storage unit.

Next, the operation of the printer 100 configured as above will be described. Since the operation of the inkjet head 110 is characteristic of the operation of the printer 100, the operation related thereto will be mainly described.

4A and 4B are diagrams showing the operation of the actuator formed by the protrusion PRA of the piezoelectric unit 2 and the electrodes 3 and 5. FIG.
As described above and shown in FIG. 4, the inkjet head 110 includes a structure in which the electrodes 3 and 5 are provided on both sides of the protrusion PRA.
Since the electrode 5 is grounded, when the potential of the electrode 3 is 0V, no electric field acts on the protrusion PRA, and the protrusion PRA maintains a plate shape as shown in the center of FIG.

When the level of the drive signal supplied to the electrode 3 is +Va, an electric field generated according to the potential difference between the electrodes 3 and 5 acts on the protrusion PRA, and the protrusion PRA is formed as shown on the left side in FIG. is bent leftward in the drawing at the joint surface between the first piezoelectric member 21 and the second piezoelectric member 22 .
When the level of the driving signal supplied to the electrode 3 is -Va, an electric field generated according to the potential difference between the electrodes 3 and 5 acts on the protrusion PRA, and the protrusion PRA is formed as shown on the right side in FIG. The PRA deforms so as to bend to the right in the figure at the joint surface between the first piezoelectric member 21 and the second piezoelectric member 22 .
However, FIG. 4 schematically shows how the protrusion PRA is deformed, and does not strictly represent the state after deformation and the amount of deformation.

When the protrusion PRA is in the left state in FIG. 4, the volume of the pressure chamber CHA adjacent to the protrusion PRA is increased compared to when the protrusion PRA is in the state shown in the center of FIG. Also, when the protrusion PRA is in the state shown on the right side in FIG. 4, the volume of the pressure chamber CHA adjacent to the protrusion PRA is reduced compared to when the protrusion PRA is in the state shown in the center of FIG. Thus, the protrusion PRA and the electrodes 3 and 5 constitute an actuator for changing the volume of the pressure chamber CHA.
Although not shown, the protrusion PRB and the electrodes 4 and 5 also expand the volume of the adjacent pressure chamber CHA when the level of the drive signal supplied to the electrode 4 is +Va, and the pressure chamber CHA is supplied to the electrode 4. An actuator is configured to reduce the volume of the adjacent pressure chamber CHA when the level of the drive signal is -Va.

In the inkjet head 110, by changing the volume of each of the plurality of pressure chambers CHA, the amount of ink droplets ejected at one time is changed. The change in the volume of the pressure chamber CHA is defined as a cycle in which a neutral state, which will be described later, returns to the neutral state through a draw period and a push period. The draw period is a period for adjusting the amount of ink contained in the pressure chamber CHA. The push period is a period during which the ink contained in the pressure chamber CHA is ejected from the nozzles 71 .

In the neutral state and during the draw period, the supply unit 108 is controlled by the supply control unit 109 so that ink is supplied if ink is sucked into the pressure chamber CHA. In the neutral state and during the draw period, the supply unit 108 is controlled by the supply control unit 109 so that if ink is pushed out from the pressure chamber CHA, the ink is recovered. During the push period, the supply unit 108 is controlled by the supply control unit 109 so that neither ink supply nor ink recovery is performed.

Several drive patterns for causing ink ejection from the inkjet head 110 will be described below with reference to FIGS. 5 to 14. FIG. Here, attention is paid to the ejection of ink from one pressure chamber CHA.
In FIGS. 5 to 14, the deformation of the protrusions PRA and PRB is shown on the upper side, with the electrodes 3, 4 and 5 omitted. The upper signal waveform shown in FIG. 5 shows the waveform of the drive signal supplied to the electrode 3 (hereinafter referred to as the first drive signal), and the lower signal waveform shows the waveform of the drive signal supplied to the electrode 4 (hereinafter referred to as the first drive signal). , referred to as a second drive signal).

FIG. 5 is a diagram showing the first drive pattern.
The neutral state is a state in which neither the protrusions PRA, PRB adjacent to the pressure chamber CHA are deformed. In the neutral state, the signal levels of both the first drive signal and the second drive signal are zero.
In the first drive pattern, the signal level of both the first drive signal and the second drive signal is +Va in the draw period PA. This expands the volume of the pressure chamber CHA to the maximum. Assuming that the amount of ink contained in the pressure chamber CHA in this state is 100%, the amount of ink contained in the pressure chamber CHA in the neutral state is 50%. In the first drive pattern, the signal level of the first drive signal is 0 and the signal level of the second drive signal is +Va during the push period PB. This reduces the volume of the pressure chamber CHA. In this state, the amount of ink contained in pressure chamber CHA is 75%. Thus, in the first drive pattern, an amount of ink equivalent to 25% is ejected from the nozzles 71 .

FIG. 6 is a diagram showing the second drive pattern.
In the second drive pattern, the signal level of the first drive signal is +Va and the signal level of the second drive signal is 0 in the draw period PA. As a result, the volume of the pressure chamber CHA expands until the ink amount reaches 75%. In the second drive pattern, the signal levels of both the first drive signal and the second drive signal are 0 during the push period PB. As a result, a neutral state is established, and the volume of the pressure chamber CHA is reduced until the ink amount reaches 50%. Thus, in the second driving pattern, an amount of ink equivalent to 25% is ejected from the nozzles 71. FIG.

FIG. 7 is a diagram showing a third drive pattern.
In the third drive pattern, the signal levels of both the first drive signal and the second drive signal are 0 in the draw period PA. As a result, the volume of the pressure chamber CHA does not change, and the amount of ink is 50%. In the third drive pattern, the signal level of the first drive signal is -Va and the signal level of the second drive signal is 0 in the push period PB. As a result, the volume of the pressure chamber CHA is reduced until the ink amount reaches 25%. Thus, in the third driving pattern, an amount of ink equivalent to 25% is ejected from the nozzles 71 .

FIG. 8 is a diagram showing a fourth drive pattern.
In the fourth drive pattern, the signal level of the first drive signal is -Va and the signal level of the second drive signal is 0 in the draw period PA. As a result, the volume of the pressure chamber CHA is reduced until the ink amount reaches 25%. However, the ink pushed out from the pressure chamber CHA at this time is recovered by the supply unit 108 and is not ejected from the nozzle 71 . In the fourth drive pattern, the signal levels of both the first drive signal and the second drive signal are -Va during the push period PB. This reduces the volume of the pressure chamber CHA to the minimum. Even in this state, ink may still be contained in the pressure chamber CHA, but here, the amount of ink in this state is assumed to be 0%. Thus, in the fourth drive pattern, an amount of ink equivalent to 25% is ejected from the nozzles 71 .

FIG. 9 is a diagram showing a fifth drive pattern.
In the fifth drive pattern, the signal levels of both the first drive signal and the second drive signal are +Va in the draw period PA. As a result, the volume of the pressure chamber CHA is expanded until the ink amount reaches 100%. In the fifth drive pattern, the signal levels of both the first drive signal and the second drive signal are 0 during the push period PB. As a result, the volume of the pressure chamber CHA is reduced until the ink amount reaches 50%. Thus, in the fifth driving pattern, the amount of ink corresponding to 50% is ejected from the nozzles 71 .

FIG. 10 is a diagram showing a sixth drive pattern.
In the sixth drive pattern, the signal level of the first drive signal is +Va and the signal level of the second drive signal is 0 in the draw period PA. As a result, the volume of the pressure chamber CHA expands until the ink amount reaches 75%. In the sixth drive pattern, the signal level of the first drive signal is -Va and the signal level of the second drive signal is 0 in the push period PB. As a result, the volume of the pressure chamber CHA is reduced until the ink amount reaches 25%. Thus, in the sixth driving pattern, the amount of ink corresponding to 50% is ejected from the nozzles 71 .

FIG. 11 is a diagram showing a seventh drive pattern.
In the seventh drive pattern, the signal levels of both the first drive signal and the second drive signal are set to 0 in the draw period PA. As a result, the neutral state is maintained, and the volume of the pressure chamber CHA remains at 50% of the ink amount. In the seventh drive pattern, the signal levels of both the first drive signal and the second drive signal are -Va during the push period PB. As a result, the volume of the pressure chamber CHA is reduced until the ink amount reaches 0%. Thus, in the seventh drive pattern, the amount of ink corresponding to 50% is ejected from the nozzles 71 .

FIG. 12 is a diagram showing an eighth drive pattern.
In the eighth drive pattern, the signal levels of both the first drive signal and the second drive signal are +Va in the draw period PA. As a result, the volume of the pressure chamber CHA is expanded until the ink amount reaches 100%. In the eighth drive pattern, the signal level of the first drive signal is -Va and the signal level of the second drive signal is 0 in the push period PB. As a result, the volume of the pressure chamber CHA is reduced until the ink amount reaches 25%. Thus, in the eighth drive pattern, the amount of ink corresponding to 75% is ejected from the nozzles 71 .

FIG. 13 is a diagram showing a ninth drive pattern.
In the ninth drive pattern, the signal level of the first drive signal is +Va and the signal level of the second drive signal is 0 in the draw period PA. As a result, the volume of the pressure chamber CHA expands until the ink amount reaches 75%. In the ninth drive pattern, the signal levels of both the first drive signal and the second drive signal are -Va during the push period PB. As a result, the volume of the pressure chamber CHA is reduced until the ink amount reaches 0%. Thus, in the ninth drive pattern, an amount of ink equivalent to 75% is ejected from the nozzles 71 .

FIG. 14 is a diagram showing a tenth drive pattern.
In the tenth drive pattern, the signal levels of both the first drive signal and the second drive signal are +Va in the draw period PA. As a result, the volume of the pressure chamber CHA is expanded until the ink amount reaches 100%. In the tenth drive pattern, the signal levels of both the first drive signal and the second drive signal are -Va during the push period PB. As a result, the volume of the pressure chamber CHA is reduced until the ink amount reaches 0%. Thus, in the tenth drive pattern, an amount of ink equivalent to 100% is ejected from the nozzles 71 .

As described above, in the first to fourth driving patterns shown in FIGS. 5 to 8, the same amount of ink droplets is ejected. In the fifth to seventh drive patterns shown in FIGS. 9 to 11, the amount of ink droplets ejected is the same, and the amount is doubled compared to the first to fourth drive patterns. In the eighth and ninth drive patterns shown in FIGS. 12 and 13, the amount of ink droplets ejected is the same, and the amount is three times that of the first to fourth drive patterns. In the tenth drive pattern shown in FIG. 14, the amount of ejected ink droplets is four times that of the first to fourth drive patterns.

On the other hand, focusing on the first drive signal and the second drive signal, for example, the first drive signal of the first drive pattern and the second drive signal of the second drive pattern have the same waveform. A drive signal is included. In summary, there are six types of waveforms of the first drive signal and the second drive signal.

FIG. 15 is a diagram showing six types of waveforms of the first drive signal and the second drive signal.
Note that FIG. 15 also shows the signal level for returning to the neutral state after the push period PB.
The drive signal SA corresponds to the second drive signal of the second drive pattern, the second drive signal of the third drive pattern, and the second drive signal of the sixth drive pattern. The drive signal SB is a first drive signal of the first drive pattern, a first drive signal of the second drive pattern, a first drive signal of the fifth drive pattern, and a second drive signal of the fifth drive pattern. The drive signal and the second drive signal of the eighth drive pattern correspond. The drive signal SC corresponds to the second drive signal of the first drive pattern. The drive signal SD corresponds to the first drive signal of the fourth drive pattern. The drive signal SE includes the first drive signal of the third drive pattern, the second drive signal of the fourth drive pattern, the first drive signal of the seventh drive pattern, and the second drive signal of the seventh drive pattern. The drive signal corresponds to the second drive signal of the ninth drive pattern. The drive signal SF includes the first drive signal of the sixth drive pattern, the first drive signal of the eighth drive pattern, the first drive signal of the ninth drive pattern, and the first drive signal of the tenth drive pattern. The drive signal and the second drive signal of the tenth drive pattern correspond.
The plurality of drive signals generated by the waveform generator 82 are the six types of drive signals SA to SF described above. Waveform generator 82 is thus an example of a generator.

As described above, the inkjet head 110 is capable of gradation reproduction in 4 gradations by multi-drop. In the printer 100 of the present embodiment, 16-gradation printing is possible by forming one pixel by ejecting ink droplets four times. The pixel data included in the line data each represents a gradation value of "0" to "15".

FIG. 16 is a diagram schematically showing the contents of the lookup table built into the LUT converter 835. As shown in FIG.
In the lookup table shown in FIG. 16, the drive signal SA is used as the first drive signal and the second drive signal for each of the first to fourth drops to realize the grayscale value in association with the grayscale value. to drive signal SF to be supplied.
When the LUT converter 835 receives the pixel data from the pixel separator 81, it controls the selectors 831 and 832 so that the driving signals associated with the gradation values represented by the pixel data are sequentially selected.

For example, if the gradation value represented by the given pixel data is "1", the LUT converter 835 outputs the drive signal SB and the drive signal SB as the first drive signal and the second drive signal for the first drop. Selectors 831 and 832 are controlled to output SA respectively. Also, the LUT converter 835 controls the selectors 831 and 832 so as to output the drive signal SA as the first drive signal and the second drive signal for the second to fourth drops. In other words, the LUT converter 835 controls the selectors 831 and 832 so that the first drop causes ink ejection according to the second drive pattern, and the second to fourth drops do not cause ink ejection. As a result, one pixel is formed with an amount of ink equivalent to 25% of the amount described above. The amount of ink ejected at this time is referred to as a unit amount.

For example, if the gradation value represented by the given pixel data is "2", the LUT converter 835 uses the drive signal SB as both the first drive signal and the second drive signal for the first drop. Selectors 831 and 832 are controlled to output. That is, the LUT converter 835 causes ink ejection according to the fifth drive pattern as the first drop. The LUT converter 835 controls the selectors 831 and 832 so as not to cause ink discharge for the second drop to the fourth drop as described above. As a result, one pixel is formed with an amount of ink equivalent to 50%, that is, an amount twice the unit amount.

For example, if the gradation value represented by the given pixel data is "3", the LUT converter 835 outputs the drive signal SF and the drive signal SF as the first drive signal and the second drive signal for the first drop. Selectors 831 and 832 are controlled to output SE respectively. In other words, the LUT converter 835 causes ink ejection according to the ninth drive pattern as the first drop. The LUT converter 835 controls the selectors 831 and 832 so as not to cause ink discharge for the second drop to the fourth drop as described above. As a result, one pixel is formed with an amount of ink equivalent to 75%, that is, an amount three times the unit amount.

For example, if the gradation value represented by the given pixel data is "4", the LUT converter 835 uses the drive signal SF as both the first drive signal and the second drive signal for the first drop. Selectors 831 and 832 are controlled to output. In other words, the LUT converter 835 causes ink ejection according to the tenth driving pattern as the first drop. The LUT converter 835 controls the selectors 831 and 832 so as not to cause ink discharge for the second drop to the fourth drop as described above. As a result, one pixel is formed with an amount of ink equivalent to 100%, that is, an amount four times the unit amount.

For example, if the gradation value represented by the given pixel data is "5", the LUT converter 835 uses the drive signal SF as both the first drive signal and the second drive signal for the first drop. Selectors 831 and 832 are controlled to output. For the second drop, the LUT converter 835 controls the selectors 831 and 832 to output the drive signal SB and the drive signal SA as the first drive signal and the second drive signal, respectively. In other words, the LUT converter 835 causes ink ejection according to the tenth drive pattern as the first drop, and causes ink ejection according to the second drive pattern as the second drop. The LUT converter 835 controls the selectors 831 and 832 so as not to cause ink discharge for the third and fourth drops as described above. Thus, one pixel is formed with a total of five times the unit amount of ink by ejecting four times the unit amount of ink and ejecting the unit amount of ink as described above.

For example, if the gradation value represented by the given pixel data is "10", the LUT converter 835 outputs both the first drive signal and the second drive signal for the first drop and the second drop. The selectors 831 and 832 are controlled to output the drive signal SF. The LUT converter 835 controls the selectors 831 and 832 to output the drive signal SB as both the first drive signal and the second drive signal for the third drop. In other words, the LUT converter 835 causes ink ejection according to the tenth drive pattern as the first and second drops, and causes ink ejection according to the fifth drive pattern as the third drop. The LUT converter 835 controls the selectors 831 and 832 so as not to cause ink discharge for the fourth drop as described above. As a result, one pixel is formed with a total of 10 times the unit amount of ink by ejecting 4 times the unit amount of ink twice and by ejecting 2 times the unit amount of ink. .

For example, if the gradation value represented by the given pixel data is "15", the LUT converter 835 outputs both the first drive signal and the second drive signal for the first drop to the third drop. The selectors 831 and 832 are controlled to output the drive signal SF. For the fourth drop, the LUT converter 835 controls the selectors 831 and 832 to output drive signal SF and drive signal SE as the first drive signal and the second drive signal, respectively. In other words, the LUT converter 835 causes ink ejection according to the tenth driving pattern as the first to third drops, and causes ink ejection according to the ninth driving pattern as the fourth drop. As a result, one pixel is formed with a total of 15 times the unit amount of ink by ejecting four times the unit amount of ink three times and three times the amount of ink ejecting the unit amount. .
Thus, the selectors 831 and 832 implement a function as a selection section. Also, the LUT converter 835 is an example of a control unit.

As described above, the printer 100 ejects a unit amount of ink by the second drive pattern, ejects an amount of ink twice the unit amount by the fifth drive pattern, and ejects an amount three times the unit amount by the ninth drive pattern. 16 levels of gradation recording from 0 to 15 times the unit amount by combining the ejection of ink, the ejection of ink in an amount four times the unit amount by the tenth drive pattern, and the state in which no ink is ejected. Realize.

Now, in the above specific example, the second drive pattern is used to eject a unit amount of ink. However, by rewriting the lookup table contained in the LUT converter 835, the first, third or fourth drive pattern can also be used. For example, by rewriting the lookup table so as to set the drive signal SC as the second drive signal where the drive signal SB and the drive signal SA are set as the first drive signal and the second drive signal, respectively. , the first drive pattern can be used to eject a unit amount of ink.

Although the same amount of ink is ejected from each of the first to fourth drive patterns, in practice, due to variations in the characteristics of the piezoelectric unit 2, etc., the amount of ink ejected from each drive pattern differs from that of the ink jet head 110 . There may be errors in each In this case, it is possible to select and use a driving pattern that achieves the most preferable ejection amount for each inkjet head 110 .
The above is the same for ejection of ink at twice and three times the unit amount.

In addition, by rewriting the lookup table, it is also possible to change the ink discharge rate for multiple drops. In this case, when the unit amount, double the unit amount, or triple the unit amount of ink is ejected with a plurality of different drops, it is also possible to apply different drive patterns. . For example, for the gradation value "2", the first drive signal and the second drive signal for the first drop are the drive signal SB and the drive signal SA, and the first drive signal and the second drive signal for the second drop are the drive signal SB and the drive signal SA. By using the drive signal SD and the drive signal SE as the signals, a unit amount of ink is ejected by the third drive pattern and a unit amount of ink is ejected by the fourth drive pattern. Pixels can be formed by
That is, by combining different drive patterns, it is possible to finely adjust the amount of ink used to form one pixel.

Further, for example, if the second drive pattern is always used as described above for ejecting a unit amount of ink, the protrusion PRA will be deformed more than the protrusion PRB, and the protrusion PRA will be deteriorated. There is a possibility that the life of the inkjet head 110 may be shortened due to the large advance. In such a case, if the drive pattern is selected so as to equalize the deformation frequency of the protrusions PRA and PRB, or if the drive pattern that is used periodically is changed, the protrusions PRA and the protrusions PRB can be easily deformed. By distributing the load to the PRB, the life of the inkjet head 110 can be extended.

This embodiment can be modified in various ways as follows.
For each drive pattern other than the fifth drive pattern, the seventh drive pattern, and the tenth drive pattern, even if the first drive signal and the second drive signal are reversed, the ink ejection can be performed in any manner. can be done. Therefore, each of these drive patterns may be replaced with such a reversed drive pattern, or such a reversed drive pattern may be additionally used. It should be noted that such a reverse driving pattern can be easily realized by rewriting the lookup table.

The number of drops in multidrop can be changed arbitrarily. Also in this case, realization is possible by changing the lookup table. Also, one pixel may be formed by one ejection.

The lookup table does not have to be included in drive unit 83 . A single lookup table may be shared by a plurality of driving units 83 . The lookup table may also be stored in a storage device provided outside the inkjet head 110, such as the auxiliary storage unit 103, for example.

The specific structure of the inkjet head does not matter as long as it is capable of ejecting the same amount of ink in any of the plurality of driving patterns.

Some or all of the components of the drive IC 8 may be provided inside the printer 100 outside the inkjet head 110 as a drive circuit for the head body.

It can also be realized as a printer for other purposes, such as printing documents, printing barcodes, and printing certificates such as receipts. Alternatively, it can be implemented as a printer for purposes other than image printing, such as for forming three-dimensional objects. Therefore, the liquid to be ejected is not limited to ink, and may be a material for object formation or the like.

While several embodiments of the invention have been described, these embodiments have been presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and equivalents thereof.

DESCRIPTION OF SYMBOLS 100... Printer 101... Processor 102... Main memory 103... Auxiliary storage unit 104... Operation panel 105... Communication interface 106... Conveyance unit 107... Conveyance control unit 108... Supply unit 109... Supply control unit , 110... Inkjet head 111... Transmission path 1... Substrate 2... Piezoelectric unit 3, 4, 5... Electrode 6... Top plate 7... Nozzle plate 21... First piezoelectric member 22... Second Piezoelectric member, PRA, PRB... protrusion, 71... nozzle, 8... drive IC, 81... pixel separator, 82... waveform generator, 83... drive section, 831... selector, 832... selector, 833... amplifier, 834 ... amplifier, 835 ... LUT converter.

Claims (5)

A plurality of actuators are provided for changing the volume of a pressure chamber by deformation in response to a supplied drive signal, and liquid is ejected from the pressure chamber according to the change in the volume of the pressure chamber. A liquid ejection head capable of changing the ejection amount at one time into a plurality of steps by combining deformation patterns, and realizing any of the plurality of combinations of the deformation patterns for some steps of the plurality of steps. to drive
A plurality of drive signals for deforming the actuator in a plurality of patterns are generated in parallel, and some of the plurality of patterns are a plurality of patterns that are different from each other for realizing respective discharge amounts in a plurality of stages. and a generating unit, wherein some of the plurality of patterns are a plurality of different patterns that realize a part of the discharge amounts of the plurality of stages;
a selection unit that selects and supplies one of the plurality of drive signals generated by the generation unit to each of the plurality of actuators;
When any one of a plurality of data representing different discharge amounts is received, it indicates which of the plurality of drive signals should be supplied to each of the plurality of actuators in association with each of the plurality of data. a control unit that controls the selection unit to supply the drive signal associated with the received data to each of the plurality of actuators based on a lookup table;
A drive circuit with In association with the received data, if a plurality of drive signals for one actuator are represented in the lookup table, the control unit sequentially converts the plurality of drive signals to the corresponding one. controlling the selector to supply two actuators;
2. A drive circuit according to claim 1. a storage unit that stores the lookup table in an updatable manner;
3. The drive circuit of claim 1 or claim 2, further comprising: A plurality of actuators are provided for changing the volume of a pressure chamber by deformation in response to a supplied drive signal, and liquid is ejected from the pressure chamber according to the change in the volume of the pressure chamber. A head body that can change the discharge amount at one time into a plurality of steps by combining deformation patterns, and that at least some steps among the plurality of steps can be realized by any of the plurality of combinations of the deformation patterns. ,
A plurality of drive signals for deforming the actuator in a plurality of patterns are generated in parallel, and some of the plurality of patterns are a plurality of patterns that are different from each other for realizing respective discharge amounts in a plurality of stages. and a generating unit, wherein some of the plurality of patterns are a plurality of different patterns that realize a part of the discharge amounts of the plurality of stages;
a selection unit that selects and supplies one of the plurality of drive signals generated by the generation unit to each of the plurality of actuators;
When any one of a plurality of data representing different discharge amounts is received, it indicates which of the plurality of drive signals should be supplied to each of the plurality of actuators in association with each of the plurality of data. a control unit that controls the selection unit to supply the drive signal associated with the received data to each of the plurality of actuators based on a lookup table;
A droplet ejection head comprising: A plurality of actuators are provided for changing the volume of pressure chambers by deformation in accordance with a supplied drive signal, and ink is ejected from the pressure chambers according to changes in the volume of the pressure chambers. A head body that can change the discharge amount at one time into a plurality of steps by combining deformation patterns, and that at least some steps among the plurality of steps can be realized by any of the plurality of combinations of the deformation patterns. ,
A plurality of drive signals for deforming the actuator in a plurality of patterns are generated in parallel, and some of the plurality of patterns are a plurality of patterns that are different from each other for realizing respective discharge amounts in a plurality of steps. and a generating unit, wherein some of the plurality of patterns are a plurality of different patterns that realize a part of the discharge amounts of the plurality of stages;
a selection unit that selects and supplies one of the plurality of drive signals generated by the generation unit to each of the plurality of actuators;
When one of a plurality of pixel data representing different gradation values is received, each of the plurality of drive signals is applied to each of the plurality of actuators in association with the gradation value represented by each of the plurality of pixel data. a control unit for controlling the selection unit to supply the drive signal associated with the received pixel data to each of the plurality of actuators, based on a lookup table indicating whether to supply the
a moving unit that moves at least one of the head main body and the paper facing the head main body so as to change the relative positional relationship between the head main body and the paper;
A printer with

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