Driving device of liquid-jet head, liquid-jet device and method for driving liquid-jet head

Disclosed is a driving device of a liquid-jet head having a piezoelectric device arranged for each of nozzles and having mutually facing electrodes. The driving device includes switching devices connected in parallel to each other, one of the electrodes being connected to first ends of the switching devices for selectively ON/OFF controlling the switching devices while the other electrode is connected to a reference potential, a driving signal source to generate a driving signal connected to second ends of the switching devices, and a control unit to switch the driving signal to ON or OFF control the switching devices. At least one of the switching devices has electrically conducting properties for not ejecting a liquid drop from the nozzle with a driving signal being applied to the switching device in an ON-controlled status, and the switching devices are all ON-controlled for causing the nozzles to eject liquid drops.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The disclosures discussed herein relate to a driving device of a liquid-jet head to eject liquid drops from nozzles of the liquid-jet head, a liquid-jet device having such a driving device and a method for driving a liquid-jet head.

2. Description of the Related Art

There are various types of technologies for causing nozzles provided in a liquid-jet head to eject liquid drops.

For example, a piezo-type liquid-jet head is configured to eject liquid drops by utilizing a piezoelectric device to deform a vibrating plate constituting a wall surface of a liquid channel to change the volume of the liquid channel. Further, a thermal-type liquid-jet head is configured to eject liquid drops by utilizing a heat element to heat liquid inside a liquid channel to generate air bubbles such that the liquid drops are ejected by the pressure generated by the air bubbles. In addition, a electrostatic-type liquid-jet head is configured to eject liquid drops by utilizing electrostatic force generated between a vibrating plate and an electrode to deform the vibrating plate constituting a wall surface of a liquid channel to change the volume of the liquid channel.

Mechanical structures of the liquid-jet heads of these types may be easily simplified and downsized. Accordingly, the liquid-jet heads may be fabricated by utilizing an integrated circuit (IC) technology or a microprocessing technology markedly advanced in the recent semiconductor field, which may provide advantages for implementing high-density packaging while reducing the fabrication cost.

Further, since the liquid-jet heads of the above types electrically control ejection of liquid drops, various sizes of the liquid drops may be precisely controlled. Accordingly, it is advantageous for the liquid-jet heads of the aforementioned types to be incorporated into recording devices configured to eject microscopic liquid drops to form high definition images.

The liquid-jet device generally includes a liquid-jet head having a series of liquid drop channels including a pressure chamber containing liquid, plural nozzle arrays communicating with the pressure chamber and piezoelectric devices corresponding to the nozzles, and a driving signal generator circuit configured to generate driving signals to be applied to the piezoelectric devices. In the aforementioned configuration, the liquid-jet device is capable of ejecting liquid drops from the nozzles by applying driving signals generated from the driving signal generator circuit to the piezoelectric devices so as to change the pressure inside the pressure chamber.

Examples of wiring member to transmit the driving signals generated from the driving signal generator circuit include a flexible flat cable (hereinafter simply called “FFC”) or a flexible printed circuit board (hereinafter simply called “FPC”).

The wiring member generally includes an inductance component L, other than a resistance component R, that with a change in the current produced on induced electromotive force. The inductance component L has a property of changing the magnitude of the inductance component L based on the length of wire.

The resistance component R of the wiring member is extremely small. Hence, even if the length of wire is increased, the transmission of the driving signals will not be interfered with. However, the inductance component L changes with the length of wire or the diameter of a path, which generates the counter electromotive force ΔE (=L×(di/dt)) that represents a product of the inductance component L and the current change rate per unit time (di/dt).

When the inductance component L becomes large due to an increase in the length of the wiring member, the counter electromotive force ΔE may become too large to be ignored as noise, which may become a cause of driving waveform distortion. The noise caused by the inductance component L may appear as overshoot or undershoot in the driving waveform.

If the amount of the overshoot or undershoot occurring in the driving waveform is constant, the driving waveform and the driving signal generator circuit may be prepared based on anticipation that such driving waveform distortion will occur.

However, the magnitude of overshoot or undershoot changes with the amount of current passing through the wiring member, which indicates that the magnitude of overshoot or undershoot changes with the number of nozzles that are driven in the liquid-jet head.

That is, if the number of nozzles is small, the driving waveform distortion may be small, and if the number of nozzles is large, the driving waveform distortion may be large. Hence, the driving waveform changes with the number of driven nozzles, which may cause a change in liquid-jet properties.

Japanese Laid-open Patent Publication No. 2007-203493 (hereinafter referred to as “Patent Document 1”) discloses a technology for stabilizing ink drop ejection properties. In this technology, the inkjet printer includes plural capacitive loads to be connected to/disconnected from a supply wire of a drive pulse in parallel. The connection/disconnection conditions of the capacitive loads to the supply wire of the drive pulse are set based on either the number of nozzles driven for ejecting ink droplets or piezoelectric actuators for driving the nozzles. This makes total electrostatic capacitance of the capacitive loads to be connected to the supply wire of the drive pulse to be a constant value. As a result, the ink drop ejection properties may be stabilized.

RELATED ART DOCUMENT

Patent Document

However, the inkjet printer disclosed in Patent Document 1 may require the capacitive loads to be connected to a head end of the wiring member for transmitting the driving signals and a switching device. In addition, since the capacitive loads are difficult to be integrated in the IC or the like, the inkjet printer further requires additional components such as a capacitor. This may result in increasing the sizes of the components and cost.

SUMMARY OF THE INVENTION

Accordingly, it is a general object of at least one embodiment of the present invention to provide a driving device of a liquid-jet head, a liquid-jet device and a method for driving the liquid-jet head capable of stabilizing liquid-jet properties of the liquid-jet head without increasing sizes of its components and fabrication cost while reducing a change in driving signals applied to the liquid-jet head, which substantially eliminate one or more problems caused by the limitations and disadvantages of the related art.

In one embodiment, there is provided a driving device of a liquid-jet head, the liquid-jet head having a piezoelectric device arranged corresponding to each of nozzles, the piezoelectric device having mutually facing electrodes, and a driving signal being applied to the piezoelectric device for causing a corresponding one of the nozzles to eject a liquid drop. The driving device includes a plurality of switching devices connected in parallel to each other, one of the electrodes being connected to first ends of the switching devices for selectively ON or OFF controlling the switching devices while the other electrode is connected to a reference potential part having a reference potential; a driving signal source configured to generate a driving signal, the driving signal source being connected to second ends of the switching devices; and a control unit configured to switch the driving signal generated from the driving signal source to ON or OFF control the switching devices. In the driving device, at least one of the switching devices has electrically conducting properties for not ejecting a liquid drop from a corresponding one of the nozzles with a driving signal being applied to the switching device in an ON-controlled status, and the switching devices having the electrically conducting properties for not ejecting liquid drops from the corresponding nozzles are all ON-controlled for causing one or more of the nozzles to eject liquid drops.

In another embodiment, there is provided a method for driving a liquid-jet head, the liquid-jet head having a piezoelectric device arranged corresponding to each of nozzles, the piezoelectric device having mutually facing electrodes, and a driving signal being applied to the piezoelectric device for causing a corresponding one of the nozzles to eject a liquid drop. The driving device includes connecting one of the electrodes to a reference potential part having a reference potential; connecting the other electrode to first ends of a plurality of switching devices connected in parallel to each other for selectively ON or OFF controlling the switching devices; connecting a driving signal source configured to generate a driving signal to second ends of the switching devices, at least one of the switching devices having electrically conducting properties for not ejecting a liquid drop from a corresponding one of the nozzles with a driving signal being applied to the switching device in an ON-controlled status; and ON-controlling the switching devices having the electrically conducting properties for not ejecting liquid drops from the corresponding nozzles for causing one or more of the nozzles to eject liquid drops.

Additional objects and advantages of the embodiments will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments are described below, with reference to accompanying drawings.

Configuration of Liquid-Jet Device

FIG. 1is an appearance perspective diagram illustrating an inkjet recording device serving as a liquid-jet device according to an embodiment viewed from a front side.

The inkjet recording device includes a device main body1, a sheet-feeding tray2attached to the device main body1, and a catch tray3removably attached to the device main body1. The sheet-feeding tray2is utilized for supplying a sheet of paper (hereinafter simply called a “sheet”) and the catch tray103is utilized for receiving the sheet after having formed (recorded) an image on the sheet.

The inkjet recording device according to the embodiment further includes a cartridge attachment part4on one end part of the front surface of the device main body1(i.e., the sheet-feeding tray2and catch tray3side), such that ink cartridges are attached to the device main body1via the cartridge attachment part4. The cartridge attachment part4includes an operation/display part5such as operations buttons and a display on its surface.

The cartridge attachment part4includes ink cartridges of different colors. The ink cartridges (main tanks)10k,10c,10mand10y(also simply referred to as an “ink cartridge10” as a generic name when different colors are not considered) contain ink of different color materials such as black (K) ink, cyan (C) ink, magenta (M) ink and yellow (Y) ink. The ink cartridge10is attached to the cartridge attachment part4such that the ink cartridge10is inserted into the cartridge attachment part4from a front side to a rear side of the main body1.

The cartridge attachment part4further includes a front cover (cartridge cover)6on its front side. The front cover6is configured to open when the ink cartridge10is inserted into the cartridge attachment part4and close after the ink cartridge10has been inserted. Further, the ink cartridges10k,10c,10mand10yare in a portrait orientation and aligned parallel to one another in a horizontal direction.

The operation/display part5includes remaining ink display parts111k,111c,111mand111yconfigured to display respective remaining amounts of ink in the cartridges110k,110c,110mand110yat respective attachment positions (respective disposed positions) of the ink cartridges110k,110c,110mand110ywhen ink in the cartridges110k,110c,110mand110yare in a near end status or in an end status. The operation/display part5further includes a power button, a sheet feeding/printing restart button and a cancelling button.

Next, a mechanical part of the inkjet recording device is described with reference toFIG. 2.FIG. 2is a schematic plan diagram illustrating the mechanical part of the inkjet recording device1according to the embodiment.

In the mechanical part of the inkjet recording device1, a carriage25is slidably supported by a guide rod22and a not-illustrated sub-guide member (a guide rod, guide stay or the like) in a main-scanning direction (a longitudinal direction of a guide rod). The guide rod22serves as a main guide member laterally bridging between main side plates21A and21B, which constitute frame members of the device main body1.

The carriage25is moved by a main scanning mechanism composed of a main-scanning motor26, a driving pulley27, a driven pulley28and a timing belt29while scanning in the main-scanning direction.

Each of the four liquid-jet heads31includes a nozzle array composed of plural nozzles in the sub-scanning direction orthogonal to the main-scanning direction. The four liquid-jet heads31are attached to the carriage25with liquid-jet directions of the liquid-jet heads31being downwardly directed.

In the carriage25, driving signals from a driving signal substrate51are supplied to the liquid-jet heads31via a flexible flat cable (FCC)12attached to a rear surface of the carriage25and an intermediate substrate56attached to the carriage25.

Meanwhile, in the mechanical part of the inkjet recording device1, a transfer belt41is arranged at a position below the carriage25. The transfer belt41serves as a transferring unit configured to transfer a sheet11supplied from a not-illustrated sheet-feeding cassette in the sub-scanning direction. The transfer belt41is an endless belt that is looped over a transfer roller42and a tension roller43that are rotationally supported between not-illustrated sub-side plates. Hence, the transfer belt41rotationally travels in a belt transferring direction (i.e., the sub-scanning direction inFIG. 2) according to the rotation of the transfer roller42that is rotationally driven by a not-illustrated sub-scanning motor.

Structure of Liquid-Jet Head

Next, a structure of the liquid-jet head31is described with reference to a cross-sectional diagram of the liquid-jet head31illustrated inFIG. 3.

The liquid-jet head31includes a drive unit102and a liquid chamber unit104.

The drive unit102includes a frame member80formed of thermoplastic resin and having a hollow part80aserving as a pressure generator device accommodating space at its central part, and a pressure generator device82arranged inside the hollow part80a.

Further, common liquid chambers80band80care respectively arranged at two opposite sides of the hollow part80ain a direction orthogonal to a longitudinal direction (hereinafter also called a “short direction”) of the frame member80.

The pressure generator device82includes a rectangular base member84formed of a rigid material such as ceramics, metal, or stainless-steel, and plural piezoelectric devices86arranged in a matrix with2rows and n columns on a base member84.

Each of the piezoelectric devices86is formed of a stacked piezoelectric device illustrated inFIG. 3. Numerous internal electrodes90of the piezoelectric device86are alternately extended to opposite end faces, and each of the extended internal electrodes90is connected to a corresponding one of not-illustrated individual end face electrodes made of AgPd alloy. Further, individual end face electrodes facing other piezoelectric devices corresponding to the piezoelectric devices66of the same rows are connected to a not-illustrated common electrode on the base member84.

Although not illustrated inFIG. 3, the individual end face electrodes and the common electrode not facing the other piezoelectric devices corresponding to the piezoelectric devices86of the same rows are connected to a flexible printed circuit board (FPC) by soldering, and the common electrode is connected to a reference potential.

An electric field is generated in a stacked direction of each of the piezoelectric devices by the application of the driving signals generated from the driving signal generator circuit via switching devices, the driving signal generator circuit serving as a driving signal source. Stretching displacement occurs in each of the piezoelectric devices in the stacked direction (displacement in a d33 direction same as the electric field), and liquid drops are thus ejected from nozzles98a.

Driving Device of Liquid-Jet Head

The outline of a driving device of the liquid-jet head31according to the embodiment is described below.

FIG. 4is a block diagram illustrates a driving signal generator circuit part of the driving signal substrate51.

In the liquid-jet device1according to the embodiment, driving signals generated within the driving signal substrate51are supplied to the liquid-jet head31, which changes an internal volume of the liquid chamber to eject liquid drops.

A waveform data memory61records waveform data corresponding to sizes of liquid drops and ink-specific temperatures. In the inkjet recording device1, a control unit is configured to select waveform data, update waveform data per a predetermined time while generating the waveform data, and output digital driving waveform data.

The digital waveform data output from the waveform data memory61are converted into an analog signal by a DA converter62. The voltage and current of the converted analog signal are then amplified by a voltage amplifier circuit63and a current amplifier circuit64, respectively, and the amplified voltage and the current serve as a driving signal of the liquid-jet head31.

FIG. 5is a circuit diagram illustrating the liquid-jet head31and a driving device of the liquid-jet head31in the inkjet recording device according to the embodiment.

Since a capacitor C is formed of each of individual electrodes34facing a corresponding one of the nozzles, and a common electrode35, the liquid-jet head31has a configuration to include an electrically capacitive actuator formed of the capacitor C and the piezoelectric device86.

The common electrode35is connected to a ground GND serving as a reference potential part having a low impedance reference potential. Further, in an analog switching circuit71, each of the individual electrodes34is connected to first ends of switching devices SW1and SW2that are connected in parallel to each other.

In this embodiment, a configuration example of two switching devices SW1and SW2that are connected in parallel to each other is described. However, the number of switching devices SW that are connected in parallel to the corresponding individual electrode is not limited to two. The number of switching devices SW that are connected in parallel to one another may be two or more.

Recording data are transmitted to the analog switching circuit71via a decoder73and a level shifter72from shift registers74and75. The analog switching circuit71selects one of the piezoelectric devices86to be driven based on the recording data, and selectively ON or OFF controls the switching devices SW corresponding to the selected piezoelectric device to be driven. For example, when data “1” or data “2” are recorded as recording data into the corresponding shift register74or75to switch a signal SWON1or SWON2to a “high level”, the signal SWON1or SWON2switched to the high level serves as the driving signal to ON-control a specific one of the switching devices SW, and consequently, the driving signal is applied to the piezoelectric device86. Note that the shift registers74and75serve as a control unit of the driving device configured to switch the respective signals SWON1and SWON2to ON or OFF control the corresponding switching devices SW.

The switching device SW1includes a resistance value R1 for causing a nozzle to eject liquid drops when the switching device SW1is ON-controlled (in an ON-controlled status) to apply a driving signal to the piezoelectric device86, while the switching device SW2connected in parallel to the switching device SW1is in an OFF-controlled status. The switching device SW2includes a resistance value R2 for not causing a nozzle to eject liquid drops when the switching device SW2is ON-controlled (in an ON-controlled status) to apply a driving signal to the piezoelectric device86, while the switching device SW1connected in parallel to the switching device SW2is OFF-controlled (in an OFF-controlled status).

Note that the resistance value R2 of the switching device SW2set in this embodiment is 10 times the resistance R1 of the witching device SW1. However, the resistance values R1 and R2 are not limited to those values, and may be able to be set appropriately.

The driving signal of the liquid-jet head31is output the driving signal substrate51, the output driving signal passes through the flexible flat cable (FFC)12, and the driving signal having passed through the FFC12is supplied to the piezoelectric device86via the switching device SW.

Note that since the FFC12includes a resistance component R and an inductance component L, counter electromotive force that is a noise component may be generated in the FFC12. This may induce undershoot or overshoot in the driving waveform.

Switching Device Control and Driving Waveform

FIGS. 6A to 6Dare diagrams illustrating examples of driving waveforms applied to a piezoelectric device utilized in the inkjet recording device according to the embodiment.

FIG. 6Ais a diagram specifically illustrating a driving waveform when liquid drops are ejected from only one nozzle by ON-controlling one of the switching devices SW1while OFF-controlling all the switching devices SW2.

Further,FIG. 6Bis a diagram specifically illustrating a driving waveform when liquid drops are ejected from all the nozzles by ON-controlling all the switching devices SW1while OFF-controlling all the switching devices SW2. InFIG. 6B, a broken line illustrates the driving waveform when the liquid drops are ejected from only one nozzle illustrated inFIG. 6A.

When all the nozzles are driven as illustrated inFIG. 6B, overshoot and undershoot may be induced in the driving waveform due to the effect of the counter electromotive force generated in the FEC12. Accordingly, a voltage Vpp of a falling part of the driving waveform is increased to a voltage Vpp2while a voltage Vpp1of a rising part of the driving waveform is increased to a voltage Vpp3as illustrated inFIG. 6Bwhen comparing the case of driving the nozzles (i.e.,FIG. 6B) with the case of driving of only one nozzle inFIG. 6A.

As illustrated inFIG. 6B, since overshoot and undershoot are generated in the driving waveform, a liquid-jet speed of the case of driving all of the nozzles is increased compared to a liquid-jet speed in the case of driving only one of the nozzles. Accordingly, image quality may deteriorate due to shifting of printing positions.

FIG. 6Cis a diagram specifically illustrating a driving waveform when a driving signal is applied to only one nozzle by ON-controlling one of the switching devices SW2while OFF-controlling all the switching devices SW1. InFIG. 6C, a broken line illustrates the driving waveform when the liquid drops are ejected from only one nozzle illustrated inFIG. 6A.

In this case, a voltage Vpp4of the rising part of the driving waveform, and a voltage Vpp5of the falling part of the driving waveform are smaller than the respective voltages Vpp0and Vpp1of the case illustrated inFIG. 6A, where only one nozzle is driven by the switching device SW1. Further, the rising part of the driving waveform and the falling part of the driving waveform inFIG. 6Cexhibit gentler curves compared to those of the driving waveform inFIG. 6A. Accordingly, even if the driving signal is applied to the nozzle by ON-controlling the switching device SW2, the nozzle will not eject liquid drops.

Thus, the resistance value R2 is set in the switching device SW2such that even if the identical driving signals are applied, the driving waveforms differ between the switching device SW1and the switching device SW2. Further, even if the driving signal is applied by ON-controlling the switching device SW2, liquid drops will not be ejected from the corresponding nozzle.

Thus, when one or more nozzles of all of the nozzles in the liquid-jet head31are caused to eject liquid drops, the driving signals are applied to the nozzles by OFF-controlling the switching devices SW2corresponding to the non-ejecting nozzles. Accordingly, it may be possible to reduce the difference in the amount of current flowing through the FFC12between the case of driving only one nozzle and the case of driving all of the nozzles while causing the necessary nozzles to eject liquid drops. This may control the amount of the counter electromotive force generated in the FFC12to reduce the difference between the driving waveforms due the number of driven nozzles. As a result, liquid-jet properties of the nozzles may be stabilized.

FIG. 6Dis a diagram specifically illustrating a driving waveform when liquid drops are ejected from only one nozzle by ON-controlling one of the switching devices SW1while ON-controlling all the switching devices SW2not to eject liquid drops. InFIG. 6D, a broken line illustrates the driving waveform when the liquid drops are ejected from all of the nozzles by ON-controlling all the switching devices SW1illustrated inFIG. 6B.

In this case, the amounts of undershoot and overshoot in the driving waveform are increased compared to the case of causing only one nozzle to eject liquid drops while OFF-controlling the switching devices SW2illustrated inFIG. 6A. This is because a constant amount of current is caused to flow by ON-controlling the switching devices SW2corresponding to the non-ejecting nozzles.

However, the difference between the voltages Vpp2and Vpp6in the falling time and the difference between the voltages Vpp3and Vpp7may be reduced in comparison with the case illustrated inFIG. 6B, where liquid drops are ejected from all of the nozzles by ON-controlling the switching devices SW1corresponding to those nozzles.

Accordingly, the liquid drops may be ejected stably without any change in the liquid ejection properties due to the number of driven nozzles by reducing the difference to be subtle between the waveform obtained by driving one nozzle and the waveform obtained by driving all of the nozzles. Further, in the liquid-jet device1having the driving device of the liquid-jet head31according to the embodiment, ejection of the liquid drops is stabilized such that shifting of the printing positions will not occur. Accordingly, the liquid-jet device1may be able to output a high quality image.

As described above, the liquid-jet properties are stabilized by ON-controlling all the switching devices SW2corresponding to the non-ejecting nozzles in this embodiment. However, the switching devices SW2may alternatively be ON-controlled by detecting the number of ejecting nozzles ejecting the liquid drops, and ON-controlling the switching devices SW2to the extend in which liquid-jet properties are not degraded corresponding to the number of driven nozzles.

FIG. 7is a graph illustrating a relationship between the number of nozzles ejecting liquid drops and speeds of the liquid drops.

The graph inFIG. 7illustrates the relationship between the number of nozzles ejecting liquid drops and the speeds of the liquid drops when only the switching devices SW1are ON and OFF controlled while all the switching devices SW2are OFF-controlled.

The speeds of the liquid drops are changed due to overshoot and undershoot occurring in the driving waveform corresponding to the number of driven nozzles ejecting the liquid drops, and the speeds of the liquid drops are increased with an increase in the number of driven nozzles. In the inkjet recording device1, a change in the speeds of the liquid drops causes the shifting of the printing positions, which degrades the image quality.

Hence, the switching devices SW2may be ON-controlled by detecting the number of driven nozzles such that the speeds of the liquid drops reach a target speed V0under a condition in which the number of driven nozzles is N0CH or less (see a graph inFIG. 7). This may stabilize the speeds of the liquid drops without degrading the image quality.

The number of nozzles ejecting the liquid drops may be detected based on the image data. Hence, the liquid-jet properties may be improved while reducing the electric power consumption by changing the number of nozzles. The number of nozzles is changed by ON-controlling the switching devices SW2based on the detected number of nozzles compared to the case of ON-controlling all the switching devices SW2corresponding to non-ejecting nozzles.

Further, when R1 represents the resistance value for ejecting the liquid drops from the nozzles and R2 represents the resistance value for not ejecting the liquid drops from the nozzles under a condition in which the driving signals are applied by ON-controlling the switching devices SW, a resistance value R1′ of the switching devices SW1is set as “R1′=(R1×R2/(R2−R1))”, and a resistance value of the switching devices SW2is set as R2.

With the above settings, a synthetic resistance of the switching devices SW1and SW2that are connected in parallel to each other corresponds to the resistance value R1 for ejecting the liquid drops. Accordingly, the nozzles may be caused to eject the liquid drops under a condition in which all the switching devices SW connected in parallel are ON-controlled.

Thus, the nozzles may be able to eject the liquid drops by selectively ON or OFF controlling the switching devices SW1alone, while the switching devices SW2corresponding to all of the nozzles are ON-controlled. Controlling the switching devices SW in the aforementioned manner may be capable of reducing a change in the amount of current flowing into the FFC12to reduce a change in the driving waveform, which may stabilize the liquid-jet properties.

Further, the synthetic resistance value of the switching devices SW1and SW2connected in parallel to each other is equivalent to a generally required resistance value for ejecting the liquid drops. In addition, there is virtually no increase in an IC chip area. Hence, it may be easy to integrate the switching devices SW into one IC.

Accordingly, it may be possible to stabilize the liquid-jet properties of the liquid-jet head without increasing the sizes of its components and cost while reducing a change in the driving waveforms applied to the liquid-jet head.

Overview

As described above, among the switching devices SW1and the switching devices SW2that are connected in parallel to one another, each of the switching devices SW2includes the resistant value R2 for not causing a nozzle to eject the liquid drops when the switching devices SW2are ON-controlled to apply the driving signals. The amount of current flowing into the FFC12may be capable of falling within a predetermined range and the change in the driving waveform corresponding to the number of driven nozzles may be lowered by ON-controlling the switching devices SW2corresponding to the non-ejecting nozzles when the nozzles of the liquid-jet head31eject the liquid drops.

Thus, according to the embodiment, it may be possible to stabilize the liquid-jet properties of the liquid-jet head31. Hence, the liquid-jet head31may be capable of constantly ejecting a predetermined amount of the liquid drops. Further, in the inkjet recording device1having the driving device of the liquid-jet head31according to the embodiment, the shifting of the printing positions will not occur. Accordingly, the inkjet recording device1may be able to stably form a high quality image.

According to the above embodiments, when the liquid-jet head is to eject liquid drops, the switching devices corresponding to the non-ejecting nozzles are ON-controlled. As a result, a constant amount of current may flow in the FFC even if the number of driven nozzles is small, the amount of change in the driving waveform due to the change in the number of driven nozzles may be reduced, and the liquid-jet properties may be stabilized.

Note that the arrangements and configurations described as the above embodiment have been described heretofore for the purpose of illustration; however, the present invention should not be limited to the foregoing description of the embodiment. The present invention may be taken into practice by adding various modifications to the foregoing embodiment without departing from the gist of the invention.

This patent application is based on Japanese Priority Patent Application No. 2011-204824 filed on Sep. 20, 2011, the entire contents of which are hereby incorporated herein by reference.