JP2004160903A - Head driving controller and image recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that ejection of a liquid in the printing become instable by a residual vibration due to charging and discharging in a time period of non-printing so that quality of an image is deteriorated. <P>SOLUTION: In the case where a pressurizing chamber 46 is contracted from an initial condition prior to the printing in a time period T1 and the pressurizing chamber 46 is restored to the initial condition after the printing in a time period T2, at least the time period T1 is set to be equal to or greater than a half of a refill cycle Trefill (0.5×Trefill), thereby stabilizing a meniscus. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
[Industrial applications]
The present invention relates to a head drive control device and an image recording device.
[0002]
[Patent Document 1] Japanese Patent No. 3201073
[0003]
[Prior art]
2. Description of the Related Art An ink jet recording apparatus used as an image recording apparatus (image forming apparatus) such as a printer, a facsimile, a copying apparatus, and a plotter includes a nozzle for ejecting ink droplets and an ink flow path (ejection chamber, pressure chamber, pressurizing chamber) communicating with the nozzle. Chamber, a liquid chamber, a pressurized liquid chamber, etc.) and a pressure generating means for pressurizing the ink in the ink flow path.
[0004]
As an ink jet head, a piezoelectric element is used as a pressure generating means for pressurizing ink in an ink flow path, and a diaphragm forming a wall surface of the ink flow path is deformed to change a volume in the ink flow path to discharge ink droplets. The so-called piezoelectric type, or the so-called thermal type, in which ink droplets are ejected with pressure generated by heating ink in the ink flow path using a heating resistor to generate bubbles, An electrostatic type in which a diaphragm and an electrode to be formed are opposed to each other, and the diaphragm is deformed by an electrostatic force generated between the diaphragm and the electrode, thereby changing a volume in an ink flow path and ejecting ink droplets. And others are known.
[0005]
By the way, in an ink jet recording apparatus using a piezoelectric ink jet head, in order to prevent the occurrence of migration when the piezoelectric element (electrostrictive element) of the head is charged in advance of printing and driven in a manner of discharging after printing is completed. ,
Japanese Patent Application Laid-Open No. H11-163873 discloses that a charging current or a discharging current at the time of starting or ending printing of a head is limited, or an intermittent charging or discharging is performed, and an electrostrictive element is formed at the time of starting or ending printing. It is disclosed that voltage application or discharge is performed stepwise at the time of voltage application or discharge.
[0006]
[Problems to be solved by the invention]
However, as mentioned above
In the ink jet recording apparatus described in Patent Document 1, no consideration is given to residual vibrations caused by charging and discharging during non-printing, and droplet ejection during printing is unstable due to the residual vibrations. And the image quality is degraded.
[0007]
The present invention has been made in view of the above problems, and has as its object to provide a head drive control device and an image recording device that enable high-speed, high-quality printing.
[0008]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the head drive control device according to the present invention is configured to contract the pressurizing chamber from the initial state at time T1 prior to printing, and to expand the pressurizing chamber at time T2 after printing to complete the initial state. , And at least the time T1 is set to a half cycle or more of the refill cycle.
[0009]
The head drive control device according to the present invention controls the pressurizing chamber to contract from the initial state at a time T1 prior to printing, expands the pressurizing chamber at a time T2 after printing is completed, and returns to the initial state. T1 and T2 are configured to be set to a half cycle or more of the refill cycle.
[0010]
The head drive control device according to the present invention is configured such that when the pressurizing chamber is contracted from the initial state prior to printing, the contracted state of the pressurizing chamber is completed two or more pixels before printing starts. It is what it was.
[0011]
In each of these head drive control devices according to the present invention, the method includes a step of contracting the pressurizing chamber from an initial state prior to printing, and when the driving waveform at the time of printing is different, contracting so as to match the reference potential of the driving waveform. It is preferable that the potential that determines the state is set so as to be multiplied by the magnification.
[0012]
The head drive control device according to the present invention, when applying a drive waveform for stirring or removing the ink near the nozzles prior to printing, contracts the pressurized chamber from the initial state at time T1 prior to the drive waveform, After the application of the drive waveform, the pressure chamber is controlled to expand at time T2 to return to the initial state, and at least one of the times T1 and T2 is set to be equal to or longer than a half of the refill cycle.
[0013]
In each of these head drive control devices according to the present invention, it is preferable to adjust the time or size of contracting or expanding the pressurizing chamber based on the detection result of the detecting means for detecting the environmental condition.
[0014]
An image recording apparatus according to the present invention includes any one of the head drive control apparatuses according to the present invention that drives and controls a pressure generating unit that contracts and expands the volume of a pressurized chamber to which a nozzle of a droplet discharge head communicates. It is.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a schematic perspective explanatory view of a mechanism of an ink jet recording apparatus as an image recording apparatus according to the present invention, and FIG. 2 is a side explanatory view of the mechanism.
[0016]
This ink jet recording apparatus includes a carriage that is movable in the main scanning direction inside the recording apparatus main body 1, a recording head including an inkjet head mounted on the carriage, an ink cartridge that supplies ink to the recording head, and the like. After storing the mechanism unit 2 and the like, taking in the paper 3 fed from the paper feed cassette 4 or the manual feed tray 5, recording the required image by the printing mechanism unit 2, the paper is transferred to the paper output tray 6 mounted on the rear side. Discharge paper.
[0017]
The printing mechanism 2 holds the carriage 13 slidably in the main scanning direction (the direction perpendicular to the paper surface in FIG. 2) by a main guide rod 11 and a sub guide rod 12, which are guide members that are laterally mounted on left and right side plates (not shown). The carriage 13 is provided with an ink jet head 14 for ejecting ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (Bk) with the ink droplet ejection direction directed downward. Each ink tank (ink cartridge) 15 for supplying each color ink to the head 14 is exchangeably mounted on the upper side of the carriage 13.
[0018]
The ink cartridge 15 has an upper air port that communicates with the atmosphere, a lower supply port for supplying ink to the inkjet head 14, and a porous body filled with ink inside. The ink supplied to the inkjet head 14 by the force is maintained at a slight negative pressure. The ink is supplied from the ink cartridge 15 into the head 14.
[0019]
Here, the carriage 13 is slidably fitted to the main guide rod 11 on the rear side (downstream side in the paper transport direction), and is slidably mounted on the front guide rod 12 (upstream side in the paper transport direction). are doing. In order to move and scan the carriage 13 in the main scanning direction, a timing belt 20 is stretched between a driving pulley 18 and a driven pulley 19 that are driven to rotate by a main scanning motor 17. , And the carriage 13 is reciprocated by the forward and reverse rotation of the main scanning motor 17.
[0020]
Although the heads 14 of each color are used here as the recording head, a single head having nozzles for ejecting ink droplets of each color may be used. Further, as described later, a vibration plate that forms at least a part of the wall surface of the ink flow path and a piezo-type inkjet head that deforms the vibration plate with a piezoelectric element are used as the head 14 as described later.
[0021]
On the other hand, in order to transport the paper 3 set in the paper cassette 4 to the lower side of the head 14, the paper 3 is guided by the paper feed roller 21 and the friction pad 22, which separate and feed the paper 3 from the paper cassette 4. A guide member 23, a transport roller 24 that reverses and transports the fed paper 3, a transport roller 25 pressed against the peripheral surface of the transport roller 24, and a leading end that defines an angle at which the paper 3 is sent out from the transport roller 24. A roller 26 is provided. The transport roller 24 is driven to rotate by a sub-scanning motor 27 via a gear train.
[0022]
Further, there is provided a printing receiving member 29 which is a paper guide member for guiding the paper 3 sent from the transport roller 24 below the recording head 14 in accordance with the moving range of the carriage 13 in the main scanning direction. On the downstream side of the printing receiving member 29 in the paper transport direction, there are provided a transport roller 31 and a spur 32 that are driven to rotate in order to transport the paper 3 in the paper discharge direction. Rollers 33 and spurs 34 and guide members 35 and 36 forming a paper discharge path are provided.
[0023]
At the time of recording, the recording head 14 is driven in accordance with an image signal while moving the carriage 13 to discharge ink on the stopped paper 3 to record one line, and after the paper 3 is conveyed by a predetermined amount, the next paper is transported. Record the line. Upon receiving a recording end signal or a signal indicating that the rear end of the sheet 3 has reached the recording area, the recording operation is terminated and the sheet 3 is discharged.
[0024]
Further, a recovery device 37 for recovering from the ejection failure of the head 14 is disposed at a position outside the recording area on the right end side in the moving direction of the carriage 13. The recovery device 37 has a cap unit, a suction unit, and a cleaning unit. The carriage 13 is moved to the recovery device 37 side during printing standby, the head 14 is capped by the capping means, and the ejection opening (nozzle hole) is kept in a wet state, thereby preventing ejection failure due to ink drying. In addition, by discharging (purging) ink that is not related to printing during printing or the like, the ink viscosity of all the discharge ports is made constant, and stable discharge performance is maintained.
[0025]
When a discharge failure occurs, the discharge port (nozzle) of the head 14 is sealed by capping means, bubbles are sucked out of the discharge port with ink by a suction means through a tube, and ink or dust adhered to the discharge port surface. Is removed by the cleaning means, and the ejection failure is recovered. The sucked ink is discharged to a waste ink reservoir (not shown) provided at a lower portion of the main body, and is absorbed and held by an ink absorber inside the waste ink reservoir.
[0026]
Next, an ink jet head constituting the recording head 14 of the ink jet recording apparatus will be described with reference to FIGS. FIG. 3 is an explanatory cross-sectional view of the head along the longitudinal direction of the liquid chamber, FIG. 4 is an explanatory cross-sectional view of the head along the lateral direction of the liquid chamber, and FIG. 5 is an explanatory plan view of a main part of the head.
[0027]
The inkjet head has a flow path plate 41 formed of a single crystal silicon substrate, a vibration plate 42 joined to the lower surface of the flow path plate 41, and a nozzle plate 43 joined to the upper surface of the flow path plate 41, With these, a nozzle 45 for ejecting ink droplets, which are liquid droplets, is connected to a pressurizing chamber 46 as an ink flow path communicating through a nozzle communication passage 45a, and a common liquid chamber 48 for supplying ink to the pressurizing chamber 46 is supplied to the ink chamber. The ink supply path 17 is formed as a fluid resistance portion communicating with the supply port 49.
[0028]
Then, an electromechanical converter which is a pressure generating means (actuator means) for pressurizing ink in the pressurizing chamber 46 corresponding to each pressurizing chamber 46 on the outer surface side (the opposite side to the liquid chamber) of the vibration plate 42. A laminated piezoelectric element 52 as an element is joined, and this piezoelectric element 52 is joined to a base substrate 53. Further, between the piezoelectric elements 52, support columns 54 are provided corresponding to the partition walls 41a between the pressurizing chambers 46, 46. Here, the piezoelectric element member is divided into comb-tooth shapes by subjecting the piezoelectric element member to slit processing by half-cut dicing, and each of the piezoelectric element members is formed by a piezoelectric element 52 and a support portion 54. The structure of the support portion 54 is the same as that of the piezoelectric element 51, but is a simple support since no drive voltage is applied.
[0029]
Further, the outer peripheral portion of the diaphragm 42 is joined to the frame member 44 by an adhesive 50 including a gap material. The frame member 44 has a recess serving as a common liquid chamber 48 and an ink supply hole (not shown) for supplying ink to the common liquid chamber 48 from outside. The frame member 44 is formed by injection molding of, for example, epoxy resin or polyphenylene sulfite.
[0030]
Here, for example, the channel plate 41 is formed by anisotropically etching a single crystal silicon substrate having a crystal plane orientation of (110) using an alkaline etching solution such as an aqueous solution of potassium hydroxide (KOH) to form a nozzle communication passage 45a, The pressure chamber 46 and the concave portion and the hole serving as the ink supply path 47 are formed. However, the present invention is not limited to a single crystal silicon substrate, and other stainless steel substrates and photosensitive resins can be used.
[0031]
The vibration plate 42 is formed from a nickel metal plate, and is manufactured by, for example, an electroforming method (electroforming method). However, other vibration members such as a metal plate, a resin plate, or a joining member between a metal and a resin plate may be used. It can also be used. The vibration plate 42 has a thin portion (diaphragm portion) 55 for facilitating deformation and a thick portion (island-shaped convex portion) 56 for joining with the piezoelectric element 52 at a portion corresponding to the pressurizing chamber 46. At the same time, a thick portion 57 is also formed at a portion corresponding to the support portion 54 and a joint portion with the frame member 44, the flat surface side is bonded to the flow channel plate 41 with an adhesive, and the island-shaped convex portion 56 is formed with the piezoelectric element 52. The thick portion 57 is further joined to the support portion 54 and the frame member 44 with an adhesive 50. Here, the diaphragm 42 is formed by nickel electroforming of a two-layer structure. In this case, the thickness of the diaphragm 55 is 3 μm and the width is 35 μm (one side).
[0032]
The nozzle plate 43 forms a nozzle 45 having a diameter of 10 to 35 μm corresponding to each pressurizing chamber 46 and is bonded to the flow path plate 41 with an adhesive. As the nozzle plate 43, a metal such as stainless steel or nickel, a combination of a metal and a resin such as a polyimide resin film, silicon, or a combination thereof can be used. Here, it is formed by a Ni plating film or the like by an electroforming method. Further, the inner shape (inner shape) of the nozzle 43 is formed in a horn shape (a substantially columnar shape or a substantially truncated cone shape), and the hole diameter of the nozzle 45 is about 20 to about the diameter on the ink droplet outlet side. It is 35 μm. Further, the nozzle pitch of each row was 150 dpi.
[0033]
Further, a water-repellent treatment layer (not shown) on which a water-repellent surface treatment is performed is provided on the nozzle surface (surface in the discharge direction: discharge surface) of the nozzle plate 43. Examples of the water-repellent layer include PTFE-Ni eutectoid plating, electrodeposition coating of a fluororesin, evaporation-coated fluororesin (for example, pitch fluoride), silicon-based resin and fluorine-based resin. A water-repellent treatment film selected according to the physical properties of the ink, such as baking after the application of a solvent, is provided to stabilize the ink droplet shape and flying characteristics and obtain high-quality image quality.
[0034]
The piezoelectric element 52 includes a piezoelectric layer 61 of lead zirconate titanate (PZT) having a thickness of 10 to 50 μm / 1 and an internal electrode layer 62 of silver / palladium (AgPd) having a thickness of several μm / 1. The internal electrodes 62 are alternately stacked, and are electrically connected alternately to the individual electrodes 63 and the common electrodes 64 which are end electrodes (external electrodes) on the end surfaces. The pressurizing chamber 46 is contracted and expanded by the expansion and contraction of the piezoelectric element 52 whose piezoelectric constant is d33. When a drive signal is applied to the piezoelectric element 52 and charging is performed, the piezoelectric element 52 expands in the direction of arrow A in FIG. 3, and when the charge charged in the piezoelectric element 52 discharges, it contracts in the direction opposite to the direction of arrow A. ing.
[0035]
In addition, the end face electrode on one end face of the piezoelectric element member is divided into individual electrodes 63 by dicing processing by half-cutting, and the end face electrode on the other end face is not divided by the restriction of processing such as notch and is divided by all the piezoelectric elements 52. The conductive common electrode 64 is formed.
[0036]
An FPC cable 65 is connected to the individual electrodes 63 of the piezoelectric element 52 by solder bonding, ACF (anisotropic conductive film) bonding, or wire bonding in order to supply a drive signal. Is connected to a drive circuit (driver IC) for selectively applying a drive waveform. The common electrode 64 is provided with an electrode layer at an end of the piezoelectric element and is turned around to be connected to a ground (GND) electrode of the FPC cable 65.
[0037]
In the ink jet head configured as described above, for example, by applying a drive waveform (pulse voltage of 10 to 50 V) to the piezoelectric element 52 in accordance with a recording signal, a displacement in the stacking direction occurs in the piezoelectric element 52, and vibration is generated. The ink in the pressurizing chamber 46 is pressurized via the plate 42, the pressure increases, and ink droplets are ejected from the nozzle 45.
[0038]
Thereafter, with the end of the ink droplet ejection, the ink pressure in the pressurizing chamber 46 is reduced, and a negative pressure is generated in the pressurizing chamber 46 due to the inertia of the ink flow and the discharge process of the driving pulse, and the ink filling process is started. Transition. At this time, ink supplied from an ink tank (not shown) flows into the common liquid chamber 48, passes through the ink supply port 49 from the common liquid chamber 48, passes through the fluid resistance part 47, and is filled into the pressurizing chamber 46.
[0039]
The fluid resistance portion 47 is effective in attenuating the residual pressure vibration after ejection, but is resistant to refilling due to surface tension. By appropriately selecting the fluid resistance value of the fluid resistance unit 47, the balance between the attenuation of the residual pressure and the refill time can be achieved, and the time (drive cycle) until the transition to the next ink droplet ejection operation can be shortened.
[0040]
Next, an outline of a control unit of the inkjet recording apparatus will be described with reference to FIG.
The control unit includes a printer controller 70 and an engine controller including a head drive circuit 71. The printer controller 70 includes an interface (hereinafter, referred to as “I / F”) 72 that receives print data and the like from a host computer or the like via a cable or a network, a main control unit 73 including a CPU or the like, storage of various data, and the like. 74, a ROM 75 storing routines for various data processing, an oscillation circuit 76, and a drive waveform generating means for generating a drive waveform Pv including a plurality of drive pulses applied to the piezoelectric element 52 of the head 14. A drive waveform generation circuit 77, an I / F 78 for transmitting print data and drive waveforms developed into dot pattern data (bitmap data) to the head drive circuit 71, and a temperature detection for detecting an environmental temperature as an environmental condition And a temperature sensor 80 as means.
[0041]
The RAM 74 is used as various buffers and a work memory. The ROM 75 stores various control routines executed by the main control unit 73, font data, graphic functions, various procedures, and the like. The main control unit 73 reads out the print data in the reception buffer included in the I / F 72, converts the print data into an intermediate code, stores the intermediate code data in an intermediate buffer formed of a predetermined area of the RAM 74, and The data is developed into dot pattern data using the font data stored in the ROM 75, and stored again in a different predetermined area of the RAM 74.
[0042]
When the dot pattern data corresponding to one line of the recording head 14 is obtained, the main control unit 73 synchronizes the dot pattern data for one line with the clock signal CK from the oscillation circuit 76, and Is transmitted as serial data SD to the head drive circuit 71 via the.
[0043]
The head drive circuit 71 is mounted on a driver IC, and receives a clock signal CK from the printer controller 70 and a serial data SD as a print signal. The shift register 81 inputs the register value of the shift register 81 from the printer controller 70. A latch circuit 82 that latches with the signal LAT, a level conversion circuit (level shifter) 83 that changes the output value of the latch circuit 82, and an analog switch array (switch circuit) 84 whose on / off is controlled by the level shifter 83 Become. The switch circuit 84 is composed of an analog switch array that inputs the drive waveform Pv from the drive waveform generation circuit 77 of the printer controller 70, and is connected to the piezoelectric elements 52 corresponding to each nozzle of the recording head (inkjet head).
[0044]
The print data SD serially transferred to the shift register 81 is temporarily latched by the latch circuit 82. The latched print data is boosted by the level shifter 83 to a voltage at which the switches of the switch circuit 84 can be driven, for example, a predetermined voltage value of about several tens of volts, and is supplied to the switch circuit 84 as a switch means.
[0045]
The drive waveform Pv from the drive waveform generation circuit 77 is applied to the input side of the switch circuit 84, and the piezoelectric element 52 as pressure generating means is connected to the output side of the switch circuit 84. Therefore, for example, during a period in which the print data applied to the switch circuit 84 is “1”, the drive pulse is applied to the drive pulse piezoelectric element 52 obtained from the drive waveform Pv, and the piezoelectric element 52 expands and contracts according to the drive pulse P. . On the other hand, while the print data applied to the switch circuit 84 is “0”, the supply of the drive pulse to the piezoelectric element 52 is cut off.
[0046]
The drive waveform generation circuit 77 can be constituted by a discrete circuit, but here, a ROM storing pattern data of the drive waveform Pv, and a D / A conversion for D / A conversion of drive waveform data read out from the ROM. And a container. Here, a plurality of drive waveform patterns (including a drive waveform (hereinafter referred to as a “recovery waveform”) pattern for stirring or removing ink near the nozzle opening before printing is included in the drive waveform generating circuit 77 in advance). Is stored so that a drive waveform to be output can be selected.
[0047]
A first embodiment of a head drive control device according to the present invention included in the ink jet recording apparatus thus configured will be described with reference to FIG.
In the head drive control device according to the present invention, prior to printing, the pressurizing chamber is contracted from the initial state at time T1, and after printing, the pressurizing chamber is controlled to expand at time T2 and return to the initial state, The time T1 and / or the time T2 are set to be equal to or longer than a half cycle of the refill cycle.
[0048]
Therefore, first, a measuring method for obtaining the refill cycle will be described with reference to FIG.
A drive pulse is applied to the piezoelectric element 52 of the inkjet head as shown in FIG. The arrows in the figure indicate the timing at which ink droplets are ejected. Then, when the discharge droplet volume Mj is obtained while keeping the fall time of the discharge pulse and the rise time of the charge pulse constant and changing the holding time, the characteristics shown in FIG.
[0049]
Here, in FIG. 7B, the state in which the voltage is applied to the piezoelectric element 52 and the piezoelectric element 52 is charged is the state in which the piezoelectric element 52 is bent in the direction of arrow A in FIG. It has become.
[0050]
Next, when a discharge pulse is applied, the piezoelectric element 52 bends in the direction opposite to the direction of arrow A in FIG. 3 to expand the volume of the pressurizing chamber 46 and generate a negative pressure inside the pressurizing chamber 46. As a result, the meniscus is largely drawn from the opening of the nozzle 45 toward the pressurizing chamber 46, and at the same time, a small amount of ink flows out to the common liquid chamber 48 through the fluid resistance part 47.
[0051]
After the application of the discharge pulse, the ink is supplied from the common liquid chamber 48 to the pressurizing chamber 46 while the holding pulse is applied. Therefore, the meniscus rises toward the opening of the nozzle 45 as the ink in the pressurizing chamber 46 increases.
[0052]
At this time, there is a correlation between the ink meniscus position and the ejected droplet volume Mj. When a driving pulse indicated by a solid line in FIG. 3B is applied, ink flows from the common liquid chamber 48 and the meniscus is Indicates that it is on the way to the club. Further, when the driving pulse indicated by the broken arrow is applied, the meniscus is in a state of being maximally raised. Further, when the drive pulse indicated by the imaginary arrow is applied, the ink flows out to the common liquid chamber 48 side, indicating that the meniscus is on the way from the opening of the nozzle 45 to the pressurizing chamber 46.
[0053]
The outflow and inflow of the ink between the common liquid chamber 48 and the pressurized chamber 46 repeats the damping oscillation at the ink refill cycle Trefil, and finally the meniscus is stabilized.
[0054]
Here, the state in which the meniscus is maximally raised (at the time of the drive pulse indicated by the dashed arrow) is substantially half of the ink refill period Trefil (0.5 × Trefil), so that the ejection droplet volume Mj is maintained at the maximum. By measuring the pulse time, the refill cycle of the ink can be determined.
[0055]
Next, when a charging pulse that does not cause the ink droplet to be ejected is applied, and while the rise time is changed, a driving pulse as shown in part B in FIG. 8 is further applied to eject the ink droplet. When the ejection droplet volume Mj is obtained, the characteristics shown in FIG.
[0056]
When a charging pulse is applied to the piezoelectric element 52 in FIG. 8B, the piezoelectric element 52 bends in the direction of arrow A in FIG. If the contraction time is short (in the case of the drive pulse indicated by the solid line), the amount of ink flowing into the common liquid chamber 48 is small, so that the meniscus rises toward the opening of the nozzle 45 as the volume of the pressure chamber 46 decreases. go. On the other hand, if the contraction time is long (in the case of the drive pulse indicated by the broken line or the imaginary line), the amount of ink flowing into the common liquid chamber 48 is sufficient, so that the meniscus remains at a substantially stable position and maintains a stable state. .
[0057]
Experimentally, the rising time of the charging pulse or the total time of the rising time of the charging pulse and the time until the ink is ejected is set to half or more (0.5 × Trefil) of the ink refill cycle Trefil. Thus, it was confirmed that the meniscus stopped at an almost stable position and maintained a stable state.
[0058]
Next, a case of recording by one-way printing will be described with reference to FIGS.
In the one-way printing, as shown in FIG. 9, for example, printing is performed by ejecting ink droplets while the head H moves in the main scanning direction indicated by a solid arrow (from left to right on the paper) in FIG. At the end of a line feed after the end, the printing method moves without discharging ink droplets in the main scanning direction indicated by a dashed arrow (from right to left on the paper surface), resumes printing after feeding a predetermined amount of paper, and resumes printing.
[0059]
At this time, as shown in FIG. 10, when the reference potential of the driving pulse (driving waveform) is not zero, the printing is completed, and the electric charge of the piezoelectric element is discharged during the line feed operation. Is necessary. In the case of one-way printing, the fall time T2 at the end of printing is short, and even if the meniscus vibrates to some extent, sufficient time is allowed to start printing, so that the meniscus can be stabilized during that time. .
[0060]
However, if the pressurizing chamber 46 is set to a predetermined reference potential to contract from the initial state at time T1 prior to printing in order to start printing, as shown in FIG. If the length is short, the meniscus is not stabilized as described above, but is in a vibrating state, and the ejection state is likely to be unstable.
[0061]
Therefore, as shown in FIG. 10A, the start-up time T1 for contracting the pressurizing chamber 46 from the initial state before printing is set to be equal to or more than half (0.5 × Trefil) of the ink refill cycle Trefil. By setting, the meniscus is stabilized and the ejection state is also stabilized.
[0062]
As described above, when the pressurizing chamber is contracted from the initial state at time T1 prior to printing, and the pressurizing chamber is expanded at time T2 to return to the initial state after printing is completed, the refilling is performed at least for time T1 at least. By setting the cycle to a half cycle or more, it is possible to stabilize the nozzle meniscus at the start of printing of one-way printing, and to prevent instability of the ejection state, for example, dispersion of the ejection volume Mj, bending of the ejection direction, and the like. And high-quality images can be recorded.
[0063]
Next, the case of recording by bidirectional printing will be described with reference to FIGS.
In the bidirectional printing, as shown in FIG. 11, for example, the head moves in the main scanning direction indicated by an arrow (from left to right on the paper) in the figure to eject ink droplets to perform printing. This is a printing method in which ink droplets are ejected and moved in the main scanning direction in a direction opposite to the first direction (from right to left on the paper) after the paper is fed by a predetermined moving amount.
[0064]
At this time, if the reference potential of the drive pulse (drive waveform) is not zero as shown in FIG. 12, it is necessary for reliability to discharge the electric charge of the piezoelectric element while printing is completed and the operation at the time of line feed is performed. It is. Further, in the case of bidirectional printing, unlike the one-way printing, the time from the end of printing to the restart of printing is short, so the fall time T2 which is the time for expanding the pressurizing chamber and returning to the initial state after the printing is completed. Also, it is necessary to set so as to stabilize the meniscus.
[0065]
Therefore, by setting both the fall time T2 and the rise time T1 to be equal to or more than half (0.5 × Trefil) of the ink refill cycle Trefil, the meniscus can be stabilized and the ejection state can be stabilized.
[0066]
As described above, when the pressurizing chamber is contracted from the initial state at the time T1 prior to printing, and the pressurizing chamber is expanded at the time T2 to return to the initial state after printing is completed, the time T1 and the time T2 are set as follows. By setting the refill cycle to a half cycle or more, it is possible to stabilize the nozzle meniscus at the start of printing of one-way printing, and at the start of printing of bidirectional printing or at the end of one-line printing. For example, it is possible to prevent variations in the ejection droplet volume Mj, bend in the ejection direction, and the like, and it is possible to perform high-quality recording.
[0067]
Next, the relationship between the timing of completion of the contracted state and the dot density when the pressurizing chamber is contracted from the initial state prior to printing will be described with reference to FIG.
When the dot density is 600 dpi, the size (diameter) of one drop is about 42 μm as shown in FIG. Here, for example, assuming that ink is ejected at a drive frequency of 16 kHz, one line can be formed by setting the head to move by one dot at intervals of 62.5 μsec.
[0068]
In this case, the refill cycle of the ink of the normal head is several tens to one hundred and several tens of microseconds, so that the half of the refill cycle of the ink is half or more for two dots (two pixels). In this case, the period is 125 μsec. It is enough.
[0069]
Therefore, by raising this period up to the reference potential and setting the meniscus stabilization time, printing can be performed stably from the third dot. Therefore, as shown in FIG. 3B, the drive waveform is set so that the rise of the drive waveform is completed so that the contraction state of the pressure chamber is completed two or more pixels before the start of printing.
[0070]
As described above, when the pressurizing chamber is contracted from the initial state prior to printing, the driving waveform is set so that the contracted state of the pressurizing chamber is completed two or more pixels before the printing is started, so that the printing at the start of printing is performed. The nozzle meniscus can be stabilized, and the instability of the ejection state, for example, the variation of the ejection droplet volume Mj and the ejection direction bend can be prevented, and a high-quality image can be recorded.
[0071]
Next, a head drive control device according to a second embodiment will be described with reference to FIG.
In the case where the reference potentials of the drive waveforms at the time of printing are made different, for example, as shown in the drawing, when the drive waveform A (reference potential Va) and the drive waveform B (reference potential Vb) are required, The drive waveforms for the rising and falling pulses are prepared, the times T1 and T2 are fixed, and the control (processing) for multiplying the magnification so that the reference potential of the drive waveform at the time of printing is performed is performed.
[0072]
For example, the drive waveform generation circuit 77 includes a storage unit that stores a magnification for setting a reference potential for each drive waveform, and a processing unit that multiplies the magnification. As a result, a drive waveform B indicated by a solid line in the figure can be generated by multiplying the drive waveform A indicated by a dashed line in the figure by a predetermined magnification.
[0073]
As described above, the process includes the step of contracting the pressurizing chamber from the initial state prior to printing, and when generating and outputting a different drive waveform at the time of printing, setting the potential to determine the contracted state so as to match the reference potential of the drive waveform. By setting so that the magnification can be multiplied, it is not necessary to provide a drive waveform pattern for setting a reference potential for each drive waveform at the time of printing, and different drive waveforms can be output without increasing the storage capacity of the storage means. In addition, the rise time T1 and the fall time T2 can be easily set to half or more (0.5 × Trefil) of the ink refill cycle Trefil.
[0074]
Next, a head drive control device according to a third embodiment of the present invention will be described with reference to FIG.
In this embodiment, a drive waveform (hereinafter, referred to as a “recovery waveform RP”) for stirring or removing ink near the nozzle opening is applied before printing.
[0075]
At this time, irrespective of unidirectional printing or bidirectional printing, when applying the recovery waveform RP immediately before the start of printing, after setting to the reference potential of the driving waveform at the time of printing using the driving waveform for the rising pulse, It is set so that the recovery waveform RP is applied. This can be achieved by incorporating a configuration for performing such processing in the drive waveform generation circuit 77 of FIG. Also in this case, the rising pulse time T1 is set to be equal to or more than half (0.5 × Trefil) of the ink refill period Trefil.
[0076]
Similarly, when the recovery waveform RP is applied at the end of one-line printing, the recovery waveform Rp is applied following the driving waveform at the time of printing, and the charge of the piezoelectric element is calculated using the driving waveform for the falling pulse. Is set in the drive waveform generation circuit 77 in FIG. Here, particularly in the case of two-pass printing, it is necessary to set the falling pulse time T2 to half or more (0.5 × Trefil) of the ink refill cycle Trefil.
[0077]
As described above, when a drive waveform for stirring or removing the ink near the nozzle opening is applied before printing, the pressurizing chamber is contracted from the initial state at time T1 before the drive waveform, and after the drive waveform is applied. The pressurizing chamber is controlled to expand to the initial state by the time T2, and at least one of the times T1 and T2 is set to be equal to or longer than a half of the refill cycle to refresh the vicinity of the nozzle opening during non-printing. Therefore, it is possible to prevent the print quality from deteriorating, and also to stabilize the nozzle meniscus even at the start of the subsequent printing, thereby preventing instability of the ejection state, for example, variation in the ejection droplet volume Mj, bending of the ejection direction, and the like. Recording with higher image quality.
[0078]
Next, a head drive control device according to a fourth embodiment of the present invention will be described with reference to FIG.
When the environmental conditions, here the environmental temperature, change, the viscosity of the ink changes, so the refill cycle of the ink also changes. FIG. 16B shows a case where the environmental temperature is low (solid line), a case where the ambient temperature is normal (dashed line), and a case where the environmental temperature is high (double-dashed line).
[0079]
The higher the environmental temperature is, the shorter the refill cycle Trefill becomes. Therefore, if the refill cycle is set in the case where the use environment temperature is the lowest (the ink viscosity is high), even if the environment temperature rises further, half or more (0.5 × Trefill) of the refill cycle can be secured. .
[0080]
However, when the environmental temperature is low, the ink viscosity is high and the meniscus is difficult to move, but when the environmental temperature is high, the ink viscosity is low and the meniscus is easy to move. Therefore, when the environmental temperature is high, it is necessary to lower the reference potential to suppress the meniscus vibration as much as possible.
[0081]
Therefore, as shown in FIG. 3A, the drive waveform also depends on the environmental temperature. When the temperature is high, a driving waveform such as a driving waveform of a reference potential indicated by a two-dot chain line is selected and output according to the environmental temperature. In this case, for any of the drive waveforms of the reference potentials, the rising time T1 for contracting the pressurizing chamber prior to printing is set to be equal to or more than half (0.5 × Trefill) of the refill cycle at low temperature. .
[0082]
Also, the time for contracting and / or expanding the pressurizing chamber can be adjusted according to the detection result of the environmental temperature. In this case, too, a plurality of driving waveform patterns corresponding to the environmental temperature are provided to the driving waveform generating circuit 77. May be stored, and this may be selected and output. However, even in this case, the rising time T1 for contracting the pressurizing chamber before printing and / or the falling time T2 for expanding the pressurizing chamber after printing is completed is a half of the refill cycle (0. 5 × Trefill) or more.
[0083]
In this way, by adjusting the magnitude of the reference potential of the drive waveform or the time for contracting or expanding the pressurizing chamber based on the detection result of the environmental condition, particularly the temperature detection result from the temperature detection unit, Even if environmental conditions change, the nozzle meniscus can always be stabilized, and stable droplet ejection can be performed.
[0084]
According to the ink jet recording apparatus provided with the above-described head drive control device, it is possible to always obtain a stable high-quality image.
[0085]
In the above embodiment, the piezoelectric element is assumed to be PZT having a displacement of d33 direction, but may be a flexural vibration type PZT. However, the reliability of the element is higher when PZT having a displacement of d33 direction is used. In addition, the image recording apparatus according to the present invention is applied to an inkjet recording apparatus equipped with a droplet discharge head for discharging ink droplets, but droplets of liquid other than ink, for example, droplet discharge for discharging liquid resist for patterning The present invention can also be applied to an image recording apparatus equipped with a head, a droplet discharge head for discharging a gene analysis sample, and the like.
[0086]
【The invention's effect】
As described above, according to the head drive control device of the present invention, the pressurizing chamber is contracted from the initial state at time T1 prior to printing, and the pressurizing chamber is expanded at time T2 after printing is completed. In the case where the control is performed so as to return to, since only the time T1 or both the times T1 and T2 are set to be equal to or longer than a half cycle of the refill cycle, instability of the ejection state can be prevented and high-quality recording can be performed. .
[0087]
According to the head drive control device of the present invention, when the pressurizing chamber is contracted from the initial state prior to printing, the contraction state of the pressurizing chamber is set to be completed two or more pixels before the start of printing. Instability of the state can be prevented, and high-quality recording can be performed.
[0088]
According to the head drive control device of the present invention, a drive waveform for stirring or removing ink near the nozzle opening is applied prior to printing, and the pressurizing chamber is contracted from the initial state at time T1 prior to the drive waveform. When the pressure chamber is controlled to be expanded at time T2 after the application of the drive waveform and returned to the initial state, at least one of the times T1 and T2 is set to be equal to or longer than a half cycle of the refill cycle. Can be improved.
[0089]
According to the image recording device of the present invention, since the head drive control device of the present invention is provided, it is possible to always obtain a stable image of high print quality.
[Brief description of the drawings]
FIG. 1 is an explanatory perspective view showing an example of a mechanism of an ink jet recording apparatus as an image recording apparatus according to the present invention.
FIG. 2 is an explanatory side sectional view of a mechanism section of the recording apparatus.
FIG. 3 is an explanatory cross-sectional view of an example of an ink jet head constituting a recording head of the recording apparatus, taken along a long side of a liquid chamber of the head.
FIG. 4 is an explanatory cross-sectional view of the head taken along a liquid chamber short side direction.
FIG. 5 is an explanatory plan view of a main part of the head.
FIG. 6 is a block diagram illustrating an outline of a control unit of the recording apparatus.
FIG. 7 is an explanatory diagram for explaining a method of measuring a refill cycle used in the head drive control device according to the present invention;
FIG. 8 is an explanatory diagram for explaining a method of measuring a refill cycle when a recovery waveform is used;
FIG. 9 is an explanatory diagram for explaining a one-way printing method in the first embodiment of the head drive control device according to the present invention;
FIG. 10 is an explanatory diagram for explaining a rise time T1 and a fall time T2 in the same one-way printing method.
FIG. 11 is an explanatory diagram serving to explain a two-way printing method according to the embodiment;
FIG. 12 is an explanatory diagram for explaining a rising time T1 and a falling time T2 in the same two-way printing method.
FIG. 13 is an explanatory diagram for explaining a relationship between a dot density and a rise time;
FIG. 14 is an explanatory diagram for explaining a second embodiment of the head drive control device according to the present invention;
FIG. 15 is an explanatory diagram for explaining a third embodiment of the head drive control device according to the present invention;
FIG. 16 is an explanatory diagram for explaining a fourth embodiment of the head drive control device according to the present invention;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 13 ... Carriage, 14 ... Recording head, 41 ... Flow path plate, 42 ... Vibration plate, 43 ... Nozzle plate, 45 ... Nozzle, 46 ... Pressurizing chamber, 47 ... Fluid resistance part, 48 ... Common liquid chamber, 52 ... Piezoelectric Element: 71: head drive circuit, 77: drive waveform generation circuit, 84: switch circuit

Claims (7)

In a head drive control device that drives and controls a pressure generation unit that contracts and expands the volume of a pressurized chamber to which a nozzle of a droplet discharge head communicates, the pressurized chamber is contracted from an initial state at time T1 prior to printing, A head drive control device, wherein after the printing is completed, the pressurizing chamber is controlled to expand at a time T2 to return to an initial state, and at least the time T1 is set to be equal to or longer than a half cycle of a refill cycle. In a head drive control device that drives and controls a pressure generation unit that contracts and expands the volume of a pressurized chamber to which a nozzle of a droplet discharge head communicates, the pressurized chamber is contracted from an initial state at time T1 prior to printing, A head drive control device, wherein after the printing is completed, the pressurizing chamber is controlled to expand at a time T2 to return to an initial state, and the times T1 and T2 are set to be equal to or longer than a half of a refill cycle. In a head drive control device that drives and controls a pressure generating unit that contracts and expands the volume of a pressurized chamber to which a nozzle of a droplet discharge head communicates, when the pressurized chamber is contracted from an initial state prior to printing, printing is performed. A head drive control device set to complete the contracted state of the pressurized chamber two or more pixels before the start. 4. The head drive control device according to claim 1, further comprising a step of contracting the pressurizing chamber from an initial state prior to printing, and when a drive waveform at the time of printing is different, a reference potential of the drive waveform. The head drive control device is set so that the potential for determining the contracted state is multiplied by a magnification so as to match the following. In a head drive control device that drives and controls a pressure generation unit that contracts and expands the volume of a pressure chamber to which a nozzle of a droplet discharge head communicates, a drive waveform for stirring or removing ink near the nozzle prior to printing is provided. When applying, the pressure chamber is contracted from the initial state at time T1 prior to the drive waveform, and the pressure chamber is expanded at time T2 after application of the drive waveform and controlled to return to the initial state, At least one of the times T1 and T2 is set to be equal to or longer than a half cycle of a refill cycle. 6. The head drive control device according to claim 1, wherein a time or a size of contracting or expanding the pressurizing chamber is adjusted based on a detection result of a detecting unit that detects an environmental condition. And a head drive control device. 7. An image recording apparatus comprising a droplet discharge head having a pressure generating means for contracting and expanding the volume of a pressurized chamber communicating with a nozzle, wherein the pressure generating means of the droplet discharge head is drive-controlled. An image recording apparatus comprising the head drive control device according to any one of the above.

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