CN1150776A - Coincident drop selection, drop separation printing method and system - Google Patents

Abstract

Ink is contained under pressure in an ink reservoir. The ink travels to a nozzle, where it is retained in the nozzle by the ink surface tension. An equilibrium is created whereby no ink escapes the nozzle by ensuring that the ink pressure, plus a predetermined external electrostatic or magnetic field, is insufficient to expel the ink from the nozzle. The system can include a heater which is incorporated at the tip of the nozzle. When this heater is energized by a heater control circuit, the ink in contact with the nozzle tip is heated. Convection rapidly transports the heat over the ink meniscus. The ink is formulated so that surface tension reduces with increasing temperature. At an elevated temperature, the surface tension of the ink is reduced sufficiently that the equilibrium is broken, and ink moves out of the nozzle. At a predetermined time, the heater is turned off by the heater control circuit and the falling temperature causes the surface tension to increase. Ink continues to move out of the nozzle by its own momentum. Surface tension and the viscous flow limitation of the nozzle causes the ink drop to ''neck'' and separate from the body of ink. The ink drop then travels to the recording medium. The thermal drop on demand mechanism operates at low power, making construction of monolithic multiple nozzle print heads using a modified CMOS process practical. The print heads can include extensive fault tolerance to improve yield, device life, and reliability.

Description

Coincident drop is selected, ink droplet separates Method of printing and system

Invention field

The present invention relates to computer-controlled PRN device field. Concrete field is the print head structure of throwing in as required (DOD) print system.

Background of invention

At present many dissimilar digital control print systems have been invented, and many kinds of products are arranged at present. These print systems are used various driving mechanisms, various printed material and various recording medium. The example of the digital printing system that uses at present comprises: electronic laser photograph printer; LED electrophotographic printer; Dot matrix impacts printer; The heat-sensitive paper printer; Film recorder; The thermoplastic printer; Dyestuff scatters thermal transfer printer; And ink-jet printer. Yet, being worth although just have coml when this customary way needs expensive equipment and only has thousands of pages of duplicate of the printing of needs, this electron-like print system can not replace the mechanical art of printing effectively. Therefore need to improve numerically controlled print system, for example need and in high speed and to produce high-quality coloured image with common paper under the condition cheaply.

Inkjet printing is considered to an outstanding competitor in numerically controlled electronic printing field, because it has without impacting, low noise characteristic is used common paper, and can avoid transfer printing and the photographic fixing of toner.

Many kinds of inkjet printing mechanisms have been invented. They can be classified into continous inkjet (CIJ) or throw in as required (DOD) ink-jet. The printing technique of continous inkjet can be traced back to nineteen twenty-nine at least: the patent US1 of Hansell, 941, No. 001.

The people such as Sweet are at patent US3 in 1967, disclose a kind of array of continous inkjet nozzle in 373, No. 437, need the ink droplet of printing to be injected selectively and towards recording medium deflection. This technology is called as binary system deflection CIJ, and is included Elmjet and Scitex adopts in interior many manufacturers.

The people such as Herhz are at patent US3 in 1966, disclose a kind of method that realizes the varying optical density of print point in CIJ prints in 416, No. 153, adopt static to disperse the ink droplet stream that injects, thereby modulation are by the ink droplet quantity of aperture. This technology is used in the ink-jet printer of Iris Graphics manufacturing.

The people such as Kyser are at patent US3 in 1970, disclose a kind of DOD ink-jet printer in 946,398, and it applies high voltage to piezo-electric crystal, makes crystal crooked, thereby exert pressure and spray on demand ink droplet at ink reservoir. Invented subsequently the printer that many kinds of piezoelectric types are thrown in as required, they have utilized bending shape, propelling form, shearing form and the extruding form of piezo-electric crystal. Use the piezoelectricity DOD printer of hot melt printing ink to obtain coml success (for example Tektronix and Dataproducts printer), and make family expenses and the image resolution ratio of handling official business with printer reach 720dpi (Seiko Epson). The advantage of piezoelectricity DOD printer is to use many kinds of printing ink. Yet the piezoelectric printer structure needs complicated high-voltage driving circuit and heavy piezo-electric crystal array usually, and this requirement is imperfect in manufacturing process and aspect of performance.

The people such as Eodo are at patent GB2 in 1979, disclose a kind of electric heating DOD ink-jet printer in 007, No. 162, it to nozzle in the printing ink electric transducer (heater) that forms thermo-contact apply electric pulse. Heater is heated to rapidly very high temperature to moisture printing ink, makes a small amount of printing ink evaporate rapidly the formation bubble. The formation of these bubbles produces pressure wave, and the ink droplet that makes printing ink sprays from aperture along the edge of heater substrate. This technology is called as Bubblejet^TM(trade mark of Japanese Canon K.K.), and be widely used in from Canon, in the printer system of Xerox and other manufacturers.

The people such as Vaught are at the patent US4 of nineteen eighty-two, disclose a kind of electrical heating ink droplet spraying system in 490,728, and it also operates by forming bubble. In this system, ink droplet sprays by being located at the nozzle that is arranged in the perforated panel above the heater on perpendicular to the direction of heater substrate plane. This system is called as Thermal Ink Jet, is made by Hewlett-Packard. In this article, this term of Thermal Ink Jet is used to represent the Hewlett-Packard system and is commonly referred to Bubblejet^TMSystem.

Typical Thermal Ink Jet is printed on needs about 20 μ J (heat) in cycle of the about 2 μ s that spray each ink droplet. Each heater need to consume 10 watts driving power, and this is its shortcoming, and needs special-purpose printing ink, complicated drive circuit, and heating element is easy to damage.

The ink-jet print system that other in technical literature, also occurred, but unpopular in market at present. For example US Patent No. 4,275, and disclosed a kind of system in No. 290 when the predetermined print-head nozzle of receiving thermal pulse is consistent with the address of static pressure, just makes printing ink freely flow on the paper that separates with pad below printhead. In US Patent No. 4,737,803; 4,737,803 and 4,748, in the disclosed inkjet printing register system, when the printing ink in the print-head nozzle of receiving thermal pulse was consistent with the address of electrostatic attraction field, ink droplet just was injected on the printing paper in No. 458.

Each own pluses and minuses separately of above-mentioned ink-jet print system. Yet, generally also think in other respects and need to improve inkjet technology, need improved problem that the simplification of price, speed, quality, reliability, power consumption, structure and operation, durability and running stores etc. are for example arranged.

Summary of the invention

The name that the applicant proposes simultaneously is called ＂ liquid ink printing apparatus and the ＂ of system and the ＂ coincident drop is selected, ink droplet separates Method of printing and the application of the ＂ of system and has described new-type method and apparatus, and this method and apparatus has had obvious progress towards the improvement direction that overcomes the above-mentioned shortcoming of prior art. These inventions have important advantage in following each side, wherein relate to the ink droplet model and place precision, accessible print speed, power consumption, the thermal stress that faces when life-span and operation, and other performance characteristics of printer, also relate to the feature of manufacturability and used printing ink. A free-revving engine of the present invention is further to improve structure and the method described in these applications, thereby makes contributions for the progress of printing technique.

The theme of a distinctness of the present invention provides new as required input ink print method, and the method has been improved existing scheme. From main aspect, method of the present invention has advantage in following each side, comprising the ink droplet model with place precision, print speed, power consumption, life-span and thermal stress during operation, and other various performance characteristics of the following printer that will specify. From other importances, the present invention is in the obvious advantage of being convenient to make and the aspect such as employed ink performance has.

According to design on the one hand, the present invention includes a kind of Method of printing of throwing in as required, the step that the method comprises have (1) with (a) be higher than the power of external pipe pressure and (b) synthetic effect of a doubling force of selecting energy pulse to the printing ink addressing in the selected nozzle of printhead, the power of these coincidences is enough to make chosen printing ink part to be out-diffusion to preset range from corresponding nozzle, surpass the printing ink in the non-selected nozzle, but the printing ink overall separation that can't be connected with them; And (2) are in this address step, attract printing ink from printhead towards print area with powerful and approaching power, thereby (a) make selected ink diffusion to above-mentioned scope, the printing ink overall separation that is connected with them, and (b) non-selected printing ink is separated.

In some preferred embodiments, the ink droplet selecting arrangement comprises, heating printing ink reduces its surface tension, applies pressure above ambient atmosphere pressure at printing ink with matching therewith. In further embodiments, the ink droplet separator comprises that a predetermined printing ink conductive characteristic combines with the uniform electric field of being scheduled to.

In another kind of preferred version, the present invention includes the liquid ink printhead that a kind of heat drives, it is characterized in that, it is little to spray the required energy comparison of ink drop, and it is lower than the printing ink of above-mentioned ink droplet equal volume is elevated to the required energy of uniform temperature that is lower than the ink droplet injection temperation from the temperature that is higher than the environment ink temperature.

In another kind of preferred version, the present invention includes the as required input printer that a kind of heat drives, it is characterized in that, used printing ink at room temperature is solid, but under operating temperature, be liquid, and selecting arrangement comprises that the pressure pulse that makes variation overlaps with selectable heating, thereby reduces the viscosity of printing ink near selecteed ink droplet.

In other scheme, the invention provides the liquid ink printhead that a kind of heat drives, it is characterized in that, it is little to spray the required energy comparison of ink drop, and it is lower than the printing ink of above-mentioned ink droplet equal volume is elevated to the required energy of uniform temperature that is lower than the ink droplet injection temperation from the temperature that is higher than the environment ink temperature.

Brief description of drawings

The schematic block diagram of the simplification of Fig. 1 (a) expression routine printing equipment of the present invention.

The sectional view at one of Fig. 1 (b) expression various nozzles of the present invention top.

The hydrodynamic model that Fig. 2 (a) selects to 2 (f) expression ink droplet.

Fig. 3 (a) is illustrated in the hydrodynamic model that limits element according in the nozzle of one embodiment of the present of invention operation.

Fig. 3 (b) is illustrated in sequenced meniscus position in ink droplet selection and the separation process.

Fig. 3 (c) is illustrated in the temperature on each aspect between the ink droplet selecting period.

The surface tension that Fig. 3 (d) expression measures for various easers and the relation curve of temperature.

Fig. 3 (e) expression is applied on the nozzle heater, thereby produces the electric pulse of temperature curve shown in Fig. 3 (c).

Fig. 4 represents be used to the schematic block diagram that realizes print-head drive circuit of the present invention.

Fig. 5 represents to embody the concrete fabrication yield that is used for A4 pagewidth color print head of feature of the present invention, comprising tolerance being arranged and not having the situation of tolerance.

Fig. 6 represents to adopt the general frame of the print system of one embodiment of the invention.

Fig. 7 represents the sectional view of the print-head nozzle of one embodiment of the invention, uses it for computer simulation in Fig. 8 to 18.

Fig. 8 (a) expression is applied to the power supply subpulse that is used as single heater-driven pulse on the printhead.

Fig. 8 (b) is illustrated in during the ink droplet selection course temperature on each aspect in nozzle.

Fig. 9 is for the meniscus position of ink droplet selection course and the relation curve of time.

Fig. 1 O is illustrated in the curve of meniscus position and shape during the ink droplet selection course at 5 μ s intervals.

Figure 11 represents the resting position of printing ink meniscus before the ink droplet selection course.

Figure 12 to 17 is illustrated in meniscus position and the hot isopleth in the stages during the ink droplet selection course.

Figure 18 be illustrated in ink droplet select heat pulse begin after flow line chart during 50 μ s.

Figure 19 keeps the curve that maximum that cooling itself allows is thrown in energy.

Figure 20 represents the Three pressures cycle of oscillation as the function of time.

Figure 21 applies in the situation of an electrothermal pulse during being illustrated in period 3 of Fig. 8, in the nozzle on each aspect as the temperature of the function of time.

Figure 22 is illustrated in the time durations of Fig. 7 as the meniscus extreme position of the function of time.

Figure 23 (a), 23 (c), 23 (e), 23 (g) and 23 (i) are illustrated in hot isopleth and the ink droplet evolution process on each time point during the ink droplet injection cycle.

Figure 23 (b), 23 (d), 23 (f), 23 (h) and 23 (j) are illustrated in viscosity isopleth and the ink droplet evolution process on each time point during the ink droplet injection cycle.

Figure 24 represents the change in location of its meniscus in one-period when ink droplet is not selected.

Figure 25 represents the change in location of meniscus in an ink droplet selection cycle, does not represent that wherein ink droplet separates.

Figure 26 represents in the printhead meniscus extreme position as the function of time, and this printhead is according to half frequency work of the printhead among Figure 20 to 25.

Figure 27 represents that the meniscus position of not selected ink droplet during one-period in the printhead changes, and this printhead is according to half frequency work of the printhead among Figure 20 to 25.

Figure 28 represents the change in location of a meniscus in the printhead in an ink droplet selection cycle, and this printhead is according to half frequency work of the printhead among Figure 20 to 25. Do not represent that wherein ink droplet separates.

The detailed description of preferred embodiment

Generally speaking, the present invention has consisted of a kind of print system of throwing in as required, wherein be used for selecting the device of printed dot between selected ink droplet and unselected ink droplet, to produce an alternate position spike, but this alternate position spike deficiency so that ink droplet overcome the surface tension of printing ink and separate from the printing ink main body, and another device is provided therein, has been used for selected ink droplet is separated from the printing ink main body.

Because the ink droplet selecting arrangement separates with the ink droplet separator, so just reduced significantly needed energy when selecting the ink droplet that to print. Only there is the ink droplet selecting arrangement to be driven by the independent signal that offers each nozzle. The ink droplet separator can be a kind of or the state that is applied to simultaneously on all nozzles.

The ink droplet selecting arrangement can be chosen from following listed scheme, but is not limited only to these schemes:

1) reduces the surface tension of pressurized printing ink with Electric heating

2) produce bubble with electrical heating, the volume deficiency of bubble is so that the ink droplet ejection

3) use the piezoelectricity mode, the change deficiency of volume is so that the ink droplet ejection

4) use the electrostatic attraction mode, for each nozzle is equipped with an electrode

The ink droplet separator can be chosen from following listed scheme, but is not limited only to these schemes:

1) near (making recording medium proximity printing head)

2) approach, and the pressure of vibration printing ink

3) electrostatic attraction

4) magnetic field suction

The table of ＂ DOD printing technique index ＂ has represented to throw in as required some desirable features of printing technique. Above-mentioned table has also been listed the certain methods that is better than prior art that some embodiment in the present invention or the inventor's the relevant application adopt.

＜DOD printing technique index 〉

Index	The improvement embodiment that surmounts prior art
		High speed operation	Practicality, low price, the printhead of pagewidth has the nozzle more than 10,000. Whole A4 pagewidth printhead can be made with 300mm (12 ＂) silicon wafer of standard
High image quality	High-resolution (800dpi is enough for most purposes), six colors are processed, in order to reduce picture noise
		The full color operation	The colour that screens 800dpi by probability carries out half halftone process
The flexibility of printing ink	The operating temperature of printing ink is low, and does not need to form bubble
		Low-power requirements	Because the ink droplet selecting arrangement needn't make ink droplet spray fully, operand power is low
Low price	Whole printhead does not have microwell plate, the rate that manufactures a finished product height, and the existing CMOS manufacturing process through revising is adopted in a small amount of electrical connection
		The high rate that manufactures a finished product	Tolerance is concentrated in the printhead
High reliability	Tolerance is concentrated in the printhead. Eliminate space and section's a word used for translation oil (kogation). Reduce thermal shock.
		A small amount of electrical connection	The CMOS technique of employing standard can concentrate on shift register, control logic and drive circuit on the whole printhead
Use existing VLSI manufacturing process	Because heater-driven power is lower than 1% of hot inkjet heater driving power, can realize the compatibility of CMOS.
		The management of electronization	Can realize the new-type page compressibility of compression in 100: 1, and scheme

The deterioration of picture is also not obvious, so just makes the data volume of compression enough low, can print in real time thousands of pages any combination on the disc driver that is stored in low price

In hot ink-jet (TIJ) and piezoelectric inkjet system, the flow velocity of ink droplet is about 10 meters of per second preferably, thereby guarantees that the ink droplet that is selected can overcome ink surface tension and separates from the printing ink main body, and touches recording medium. The efficient of these systems when electric energy is converted to ink droplet kinetic energy is very low. The efficient of TIJ system approximately is 0.02%. This just means that the drive circuit for the TLJ printhead need to switch large electric current. The drive circuit of piezoelectric ink jet printing head need to switch high voltage or drive large capacity load. The total power consumption of pagewidth TIJ printhead also is very large. The A4 full color page TIJ printhead of a 800dpi was printed the electrical power that four look black white images need to consume about 6KW within one second, major part wherein has been converted into useless heat. To remove these heats be very difficult, thereby hindered the manufacturing of low price, high-speed, high-resolution small-sized pagewidth TIJ system.

A key character of the embodiment of the invention is to have reduced significantly as need selecting the required energy of ink droplet of printing with a device. This measure be by the device of selecting ink droplet with guarantee selected ink droplet separated and separate at the device that recording medium forms point from the printing ink main body to realize. Only there is the ink droplet selecting arrangement to be driven by the independent signal that offers each nozzle. And the ink droplet separator can be a kind of or the state that offers simultaneously all nozzles.

The table of ＂ ink droplet selecting arrangement ＂ has represented might be used for according to the present invention several means of selection ink droplet. The ink droplet selecting arrangement only needs to make selected ink droplet to produce enough change in location, makes the ink droplet separator can identify selected ink droplet and unselected ink droplet.

＜ink droplet selecting arrangement 〉

Method	Advantage	Restriction
				1. the electricity consumption heat drop hangs down the surface tension of pressurized printing ink	Low-temperature-rise and low ink droplet are selected energy. Can use multiple inks. Simple in structure. The CMOS drive circuit can be assembled on the same substrate.	Need the ink pressure governor motion. Ink surface tension is along with the increase of temperature must be able to descend significantly.

2. the electricity consumption heat drop hangs down ink viscosity, in conjunction with the vibration of ink pressure	Ink droplet selects the energy of usefulness moderate, is applicable to the printing ink of hot melt and oil base. Simple in structure. The CMOS drive circuit can be assembled on the same substrate.	Need the ink pressure oscillating mechanism. The viscosity of printing ink is along with the increase of temperature must significantly descend.
			3. electric heating foaming makes the volume deficiency of bubble so that the ink droplet ejection	Known technology, simple in structure. The bipolar driving circuit can be assembled on the same substrate.	Ink droplet selects energy high, needs water-based inks, has section's a word used for translation oil (kogation), cavity and thermal stress issues
4. the piezoelectricity mode makes the deficient change of volume so that the ink droplet ejection	Can use the printing ink of multiple matrix	Manufacturing cost is high, and integrated circuit technology is complicated, high driving voltage, and complex structure is heavy
			5. an electrode is joined in electrostatic attraction, each nozzle	Simplify the manufacturing of electrode	Injector spacing needs relatively large. Between the adjacent electric field interference is arranged. Need high-voltage driving circuit.

Other ink droplet selecting arrangement also can use.

Preferred ink droplet selection scheme to water-based inks is method 1: " the surface tension ＂ of the low pressurized printing ink of electricity consumption heat drop. This ink droplet selecting arrangement has been compared many advantages with other system, this is comprising: low-power operation (approximately be TLJ 1%), compatible with CMOS VLSI chip manufacturing process, low voltage operating (approximately 10V), the high density nozzle, low-temperature operation, and be widely used in various ink formulations. The surface tension of printing ink must reduce along with the increase of temperature.

Preferred ink droplet selection scheme to hot melt or oil-based ink is method 2: ＂ electricity consumption heat drop hangs down ink viscosity, in conjunction with the vibration ＂ of ink pressure. This ink droplet selecting arrangement is specially adapted to viscosity and significantly descends along with the increase of temperature, but but seldom printing ink of capillary reduction. This phenomenon is obvious especially in having the nonpolar printing ink of relatively high molecular weight. This method is specially adapted to the printing ink of hot melt or oil base.

The table of ＂ ink droplet separator ＂ has provided and has severally separated selected ink droplets from the printing ink main body, and guarantees that selected ink droplet forms the possible method of point at printed medium. The ink droplet separator is identified between selected ink droplet and unselected ink droplet, guarantees that unselected ink droplet can not form a little at printed medium.＜ink droplet separator 〉

Means	Advantage	Restriction
				1. electrostatic attraction	Can print on coarse surface, realize easily	Need high voltage source
2.AC electric field	Can obtain the field intensity higher than static, opereating specification can increase, and ink pressure reduces, and can reduce the gathering of dust	The phase locked high pressure AC power supply that need to spray with ink droplet is difficult to operation when multiple ink droplet phase place
			3. near (printhead approaches still not contact history media)	Can obtain very little point. Power consumption is very low. The precision of drop location is very high.	Need to make the very surface of proximity printing head of printed medium, not be suitable for coarse printed medium, usually need conveying cylinder or belt
4. carry near (making printhead near conveying cylinder or belt)	Can obtain very little point. Power consumption is very low. Precision is high, can print at coarse paper	Because the size restrictions of conveying cylinder or belt conveyor is compact not
			5. approach, and follow the ink pressure vibration	The hot melt printing ink that is used for the ink droplet system of selection of employing reduced viscosity, the possibility of minimizing nozzle blockage can use pigment to replace dyestuff	Require very proximity printing head surface of printed medium, be not suitable for coarse printed medium, need the ink pressure oscillation device
6. magnetic field suction	Can print at rough surface. If use permanent magnet, power are very low	Need uniform high magnetic field intensity, need magnetic ink

Also can use other ink droplet separators.

Preferred ink droplet separation scheme depends on required purposes. In great majority are used, the most suitable employing method 1: " electrostatic attraction ＂, or method 2: ＂ AC electric field ＂. At the paper that uses smooth finish or film and adopt unusually when high-speed, can using method 3: ＂ be near ＂. For high speed, high-quality system can carry near ＂ by using method 4: ＂. Method 6: ＂ magnetic field suction ＂ is applicable to portable printing system, and the printed medium that this system uses is too coarse, is not suitable for proximity printing, and does not want to adopt electrostatic drop to separate required high voltage. The ＂ ink droplet separator that does not have the ＂ the best that is applicable to significantly all environment.

Described the further details of various print systems of the present invention in the following Australian patent application specification of submitting to April 12 nineteen ninety-five, these specifications are in this article as with reference to data:

" liquid ink tolerance (LIFT) printing mechanism " (A Liquidink Fault Tolerant (LIFT) printing mechanism) (application number: PN2308);

" the electric heating ink droplet in LIFT prints is selected " (Electrothermal drop selection in LIFT printing) (application number: PN2309);

" in printing, separates LIFT " (Drop separation in LIFT printing by print media proximity) (application number: PN2310) by the approaching ink droplet that carries out of printed medium;

" in printing near LIFT, adjust ink drop size (Drop size adjustmentin Proximity LIFT printingby varying head to media distance) (application number: PN2311) by changing printhead to the distance of media;

" expansion with sound China ink ripple is printed near LIFT " (Augmenting Proximity LIFT printing with acousticink waves) (application number: PN2312);

" electrostatic drop in LIFT prints separates " (Electrostatic drop separation in LIFT printing) (application number: PN2313);

" the how synchronous ink drop size in printing near LIFT " (Multiple simultaneous drop sizesin Proximity LIFT printing) (application number: PN2321);

" the certainly cooling operation of thermal excitation printhead " (Self cooling operation in thermally activated print heads) (application number: PN2322); And

" hot sticky reduction LIFT prints " (Thermal Viscosity Reduction LIFT printing) (application number: PN2323).

The rough schematic view that in Fig. 1 (a), has represented the present invention's one routine print system.

Image source 52 can be the panel view data from scanner or computer, or adopts the contour images data of page description language (PDL) form, or other digital image form. This view data is converted to the page-images of pixel graphics by image processing system 53.

Can adopt panel image processor (RIP) for the PDL view data, can adopt pixel image to process to the panel view data. Carry out halftone process by the continuous tone data that image processing apparatus 53 produces, halftone process (Halftoning) is carried out by digital halftone treating apparatus 54. Halftone process bit map view data is stored in the video memory 72. According to the structure of printer and system, video memory can be full page face memory or belt memory. Control circuit for heater 71 is sense data from video memory 72, and provides the upper electric pulse that changes of time to the nozzle heater (103 among Fig. 1 (b)) as printhead 50 parts. These pulses offer suitable nozzle at reasonable time, and selected ink droplet is formed a little by the appropriate location of the data appointment in the video memory 72 on recording medium 51.

Recording medium 51 is moved by paper induction system 65 with respect to printhead 50, and it is be subjected to paper transport control system 66 electronically controlled, and the latter is subjected to the control of a microcontroller 315. Only be schematically to have represented the paper induction system in Fig. 1 (a), many different frame for movements all are possible. If use the printhead of pagewidth, all be moving recording media 51 below static printhead 50 generally. Yet, in the situation of scan-type print system, normally along an axis (inferior scanning direction) mobile print head 50, and along axis (main scanning direction) the mobile print media 51 of quadrature, form the relative motion of panel. Microcontroller 315 can also be controlled page pressure regulator 63 and control circuit for heater 71.

Reduce capillary printing type for adopting, printing ink is installed in the ink storage device 64 that is under the pressure. Under static state (do not have the ink droplet ejection), ink pressure is not enough to overcome the surface tension of printing ink and sprays ink droplet. Under 63 controls of ink pressure adjuster, exert pressure to ink storage device 64, just can obtain constant ink pressure. Otherwise, for larger print system, if make the end face of the printing ink in the holder 64 be in the suitable distance of printhead 50 tops, just can very accurately produce and control the pressure of printing ink. This printing ink liquid level can directly be regulated with unsteady valve (not shown).

Fall low viscous printing type for employing, printing ink is installed in the ink storage device 64 that is under the pressure, and makes ink pressure produce vibration. The device that produces this vibration can be mounted in the piezo-activator in the oil ink passage (not shown).

If the ink droplet separator can correctly be set, selected ink droplet just can form a little at printed medium 51, and unselected ink droplet then still is retained as the part of printing ink main body.

Utilize oil ink passage device 75 the rear surface of distributes ink to printhead 50. Printing ink preferably can be by the seam on the silicon chip that is etched in printhead 50 and/or orifice flow to the front that is provided with nozzle and actuator 64. In the situation that heat is selected, nozzle actuators is electrothermal heater.

In the printer according to some type of the present invention, need the field 74 of an outside to guarantee that the ink droplet of selecting moves from the separation of printing ink main body and towards recording medium 51. Habitual external field 74 is constant electric fields, because the printing ink of conduction is made easily. In this case, can make paper guider or platen 67 with conductive material, and with its electrode as the generation electric field. Another electrode can be that printhead 50 is own. Another embodiment adopts the means of proximity printing media to identify selected ink droplet and unselected ink droplet.

Because ink droplet is very little, the gravity that acts on the ink droplet is very little; Approximately be capillary 10^-4, therefore can ignore gravity as a rule. So just allow printhead 50 to align in any direction with respect to Local Gravity Field with recording medium 51. This point is an important requirement of portable printer.

Fig. 1 (b) is the cross section enlarged drawing with a micro nozzle tip of the embodiment of the invention of improved CMOS technique manufacturing. Nozzle is etched on a substrate 101, and substrate can be silicon chip, glass, metal or other suitable materials. If use the substrate of non-semiconductor material, can deposit a kind of semi-conducting material (for example non-crystalline silicon) at substrate, and can in the surface of semiconductor layer, form integrated driving transistors and data allocation circuit. Monocrystalline silicon (SCS) substrate has following several advantages:

1) in SCS, can make high performance driving transistors and other circuit;

2) adopt the VLSI process equipment of standard can under existing convenience (fabs), make printhead;

3) SCS has very high mechanical strength and rigidity; And

4) SCS has high thermal conductivity.

In this example, nozzle is columnar, and heater 103 forms a ring. The tip 104 of nozzle is that the silicon dioxide layer 102 with deposition forms during making the CMOS drive circuit. The tip silicon nitride passivation of nozzle. The outstanding contact point of nozzle tip control pressurized printing ink 100 on print head surface. Print head surface or hydrophobic diffusion occurs once in a while in case be in the procephalic printing ink of printing.

The nozzle of many other structures also is feasible, and can change the material of shape, size and use in the embodiment of nozzle of the present invention. The nozzle that is etched into monolithic with substrate when forming heater and drive circuit has an advantage, and that is exactly not need microwell plate. When making and assemble, saved microwell plate cost is reduced significantly. The method that is used at present the omission microwell plate comprises use ' eddy current ' actuator, transferred the patent US4 of Xerox in 1986 such as people such as Domoto, 580, in No. 158 and the people such as Miller transferred the patent US5 of Hewlett-Packard in 1994, actuator described in 371, No. 527. Yet these actuators are that complexity is difficult to again make. The present invention packs microwell plate in the actuator substrate into.

This nozzle can be used for adopting various technical points from the printhead of ink droplet.

The working method that electrostatic drop separates

As an example, in Fig. 2, represented the working method of utilizing heating to reduce surface tension and adopt static to separate ink droplet.

Fig. 2 has represented the Inc. with Fluid Dynamics, energy transfer and fluid dynamic simulation result that the fluid dynamic simulation software kit FIDAP of the commercialization that of Illinois USA provides carries out. This simulation is to select nozzle to realize that environment temperature is 30 ℃ with the heating ink droplet of diameter 8 μ m. The gross energy that offers heater is 276nJ, applies respectively 69 pulses that respectively account for 4nJ. Ink pressure is than the high 10KPa of ambient atmosphere pressure, and ink viscosity is 1.84cPs in the time of 30 ℃. Printing ink is water base, and comprises 0.1% hexadecanoic acid colloidal sol, is used for promoting capillary decline along with the increase of temperature. Represented in the drawings the nozzle tip cross section from the central shaft of nozzle to 40 μ m of radius distance. Adopt the material of various density, thermal capacity and thermal conductivity to simulate in the various materials of flow nozzle, comprise silicon chip, silicon nitride, noncrystal silica, crystalline silica and water base printing ink. The time interval of simulation is 0.1 μ s.

Fig. 2 (a) has represented to start heater inactive state before. Guarantee at ambient temperature to make ink pressure to add that outside electrostatic field is not enough to overcome the surface tension of printing ink, thereby produce a kind of balance, printing ink under static state can not overflowed from nozzle. Under static state, the meniscus of printing ink can not given prominence to from the surface of printhead significantly, and therefore, electrostatic field can not concentrate on the meniscus significantly.

Fig. 2 (b) be illustrated in the heater driving pulse start after 5 ℃ of hot isopleth during the 5 μ s of interval. When heater was subject to encouraging, the printing ink that contacts with nozzle tip was heated rapidly. The heated portion that capillary decline makes meniscus extends rapidly with respect to the meniscus of cold oil China ink. The convection current that causes is thus transferred to rapidly on the whole Free Surface of printing ink at nozzle tip place heat. Heat should be assigned on the whole ink pellet surface, rather than only concentrate on printing ink that heater contacts in. This is because stoped the movement of the printing ink that directly contacts with heater with respect to the viscosity resistance of solid heater.

5 ℃ of hot isopleth when Fig. 2 (c) has represented after the heater driving pulse starts interval 10 μ s. The increase of temperature reduces surface tension, has upset equilibrium of forces. Along with whole meniscus is heated, printing ink begins to flow.

Fig. 2 (d) be illustrated in the heater driving pulse start after 5 ℃ of hot isopleth during the 20 μ s of interval. The pressure of printing ink has made printing ink flow to a new meniscus position, and meniscus is outstanding from printhead.

Fig. 2 (e) be illustrated in the heater driving pulse start after 5 ℃ of hot isopleth during the 30 μ s of interval since the duration of heater pulse be 24 μ s, this moment also be after heater pulse finishes 6 μ s constantly. Because the conduction of oxide layer, nozzle tip has cooled off rapidly, and is transmitted to mobile printing ink. Printing ink has played effective ＂ water-cooled ＂ effect to nozzle tip. Electrostatic attraction makes ink droplet begin to accelerate towards recording medium. If heater pulse obviously shortens (for example less than 16 μ s), printing ink just can not accelerate towards recording medium, but in the nozzle of can retracting.

5 ℃ of hot isopleth after Fig. 2 (f) expression heater pulse finishes during the 26 μ s of interval. The temperature at nozzle tip place exceeds 5 ℃ of less thaies than environment temperature at this moment. Nozzle tip surface tension is on every side increased. When the speed that is drawn out of from nozzle when printing ink has surpassed the speed that is subjected to viscous force restriction when printing ink is flowed through nozzle, the printing ink in the nozzle tip zone will ' shrink ', and selected ink droplet will separate from the printing ink main body. Selected ink droplet externally flows on the recording medium under the effect of electrostatic field subsequently. And the printing ink meniscus at nozzle tip place will return to its resting position at this moment. Wait for that next heat pulse removes to select next ink droplet. Each heat pulse is selected and is separated an ink droplet, and forms a point in recording medium. Because heat pulse just can realize the inkjet printer operation of throwing in as required by circuit control.

Fig. 3 (a) according to 5 μ s time interval from the ink droplet selection cycle that the heater starting pulse begins the order meniscus position.

Fig. 3 (b) is meniscus position with respect to the curve of time, has represented the movement of meniscus central point. 10 μ s enter simulation after heater pulse begins.

Fig. 3 (c) is illustrated in the nozzle temperature on each aspect with respect to the relation curve of time. The longitudinal axis of curve represents temperature, and unit is 100 ℃. The transverse axis of curve represents the time, and unit is 10 μ s. Temperature curve shown in Fig. 3 (b) is to utilize FIDAP to calculate according to the time interval of 0.1 μ s. Local ambient temperature is 30 ℃. Represented in the drawings the thermograph on three points.

A-nozzle tip: represented passivation layer, the thermograph between printing ink and the air in the contact circulation.

B-meniscus mid point: this point is the middle circle of printing ink meniscus between nozzle tip and the meniscus center.

The C-chip surface: this point is on the print head surface apart from nozzle center 20 μ s places. Temperature has only risen the several years. This show function circuit can be very near nozzle, and can not affect owing to the rising of temperature performance or reduce the life-span.

Fig. 3 (e) expression offers the power of heater. Best operation requirements temperature sharply rises in the starting point of heater pulse, at impulse duration temperature is maintained slightly to be lower than the printing ink boiling point, and when end-of-pulsing temperature is descended rapidly. Need to change the average energy that offers heater at whole impulse duration for this reason. In this case, be that the energy that pulse frequency modulated by 0.1 μ s slave pulses obtains each slave pulses of this change is 4nJ. The peak power that offers heater is 40mW, and the mean power during heater pulse is whole is 11.5mW. The slave pulses frequency of this moment is 5MHz. This point is easy to change, and can not affect significantly the operation of printhead. Higher slave pulses frequency can realize more accurate control in the process that power is provided to heater. Suitable slave pulses frequency is 13.5MHz, because this frequency also is fit to reduce to greatest extent the impact of Radio frequency interference (RFI).

Surface tension has the printing ink of negative temperature coefficient

The surface tension of printing ink is increased along with temperature and the requirement that reduces is not a main restriction, because most of pure liquid and many mixtures all have this character. For liquid arbitrarily, there is not the exact relationship formula of surface tension and temperature. Yet the following empirical equation of being derived by Ramsay and Shields can be fit to many liquid: ${\mathrm{\γ}}_T=k\frac{(T_c-T-6)}{\sqrt[3]{{\left(\frac{\mathrm{Mx}}{\mathrm{\ρ}}\right)}^2}}$

γ wherein_TBe the surface tension of temperature when being T, k is a constant, and Tc is the critical-temperature of liquid, and M is the molecular weight of liquid, and x is association (association) degree of liquid, and ρ is the density of liquid. This formula shows that the surface tension of most liquid can drop to zero when temperature reaches the critical-temperature of liquid. Under atmospheric pressure, the critical-temperature of most liquid all is higher than its boiling point significantly, therefore, in order to obtain the larger variation of ink surface tension with less variations in temperature near the injection temperation of reality, needs to add surfactant.

The selection of surfactant is very important. For example, the water-based inks that is used for thermal ink jet printers usually comprises for reducing surface tension and impels its rapidly dry isopropyl alcohol (2-propyl alcohol). The boiling point of isopropyl alcohol is 82.4 ℃, is lower than the boiling point of water. Along with the increase of temperature, alcohol is vaporized quickly than water, the concentration of alcohol is reduced, and surface tension is increased. Surfactant such as 1-ethanol (b.p.158 ℃) can be used for offseting this effect, and obtains with temperature a little surface tension of decline. Yet, in order to increase opereating specification as far as possible, need to make the surface tension decline relatively large along with temperature has. Preferably make the surface tension 20mN/m that in 30 ℃ temperature range, can descend, in order to obtain large opereating specification, in order to satisfy the action need of printhead of the present invention, minimumly will adopt 10mN/m.

Has large-Δ γ_TPrinting ink

Can come to make surface tension obtain larger negative variation along with the increase of temperature with several method. Two kinds of these class methods are as follows:

1) printing ink can comprise the surfactant colloidal sol of low concentration, and this colloidal sol is solid at ambient temperature, but dissolves under a threshold temperature. Granularity should be less than 1000A. The suitable molten point of the surfactant of water-based inks is between 50 ℃ to 90 ℃, preferably is between 60 ℃ to 80 ℃.

2) printing ink can comprise a kind of micro emulsion of oil/water, and its phase inversion temperature (PIT) is higher than high ambient temperature, but is lower than the boiling point of printing ink. For stable, the PIT of micro emulsion preferably be on the highest nonoperating temperature that printing ink can run into more than 20 ℃. Suitable PIT value approximately is 80 ℃.

The printing ink that contains surfactant colloidal sol

In the printing ink of preparation, the granule colloidal sol of surfactant is dissolved in the operating temperature range of appointment. The example of this surfactant comprises the carboxylic acid with 14 to 30 carbon atoms, for example:

Title	General formula	m.p.	Different name
				Tetradecanoic acid	CH 3(CH 2) 12COOH	58℃	Myristic acid
Hexadecanoic acid	CH 3(CH 2) 14COOH	63℃	Palmitic acid
				Octadecanoid acid	CH 3(CH 2) 15 COOH	71℃	Stearic acid
Arachic acid	CH 3(CH 2) 16COOH	77℃	Arachidic acid
				Behenic acid	CH 3(CH 2) 20 COOH	80℃	Behenic acid

Owing to have the molten point of colloidal sol of small particle size usually a shade below the material of bulky grain degree, preferably select a kind of molten carboxylic acid slightly higher than required ink droplet selection temperature. A kind of good example is arachic acid.

Can be with having bought at a low price the highly purified carboxylic acid of this class. Therefore the amount of needed surfactant seldom, is added activating agent cost is obviously increased in different name. The mixed carboxylic acid of the length slight change of chain can be used for making molten point to be distributed in certain temperature range. The price of this mixture is usually low than pure acid.

The selection of surfactant not necessarily is limited in simple without branch's carboxylic acid. Also can use with side chain or phenyl or the surfactant of other hydrophobic ingredients. And also not necessarily to use carboxylic acid. The composition of many high degree of polarization can be used for the water-wet side of surfactant. Polarization end should be able to be at the water intermediate ion, thereby makes the surface charging of surfactant granules, helps like this to disperse and prevent flocculation. If the use carboxylic acid can be realized by adding basic species such as NaOH or potassium hydroxide.

Preparation with the printing ink of surfactant colloidal sol

The surfactant colloidal sol that can prepare separately high concentration, and add in the printing ink by needed concentration.

The concrete grammar of making surfactant colloidal sol is as follows:

1) in the environment of anoxic, in pure water, adds carboxylic acid.

2) mixture is heated to more than the molten point of carboxylic acid. Can make the water boiling.

3) mixture is carried out supersonic oscillations, until the typical size of carboxylic acid ink droplet is between the 100A to 1000A.

4) make the mixture cooling.

5) above mixture, analyse larger particle.

6) add for example alkaline matter of NaOH, make the carboxylic acid molecules ionization on the particle surface. Suitable pH value is 8. This step not necessarily still helps to make Stability of Sols.

7) colloidal sol is done centrifugal treating. Because the proportion of carboxylic acid is lower than water, little particle is concentrated in the outside of centrifuge, and large particle is in the center.

8) filter colloidal sol with millipore filter, remove any particle greater than 5000A.

9) in the printing ink of preparation, add surfactant colloidal sol. Colloidal sol only needs very rare concentration.

The printing ink of preparation can also comprise dyestuff or pigment, bactericidal additive, when using electrostatic drop to separate for increasing the additive of printing ink electric conductivity, wetting agent, and other additives that need.

Usually do not need to put the foam agent, because in the ink droplet course of injection, can not form bubble.

Cationic surfactant colloidal sol

The printing ink made from cationic surfactant colloidal sol is not suitable for using with cationic dyestuff or pigment usually. This is because cationic dyestuff or pigment may form precipitation or flocculation with cationic surfactant. In order to use cationic pigment or dyestuff, need a kind of colloidal sol of cationic surfactant. Alkylamine family is applicable to this purposes.

Various suitable alkylamine families are as shown in the table:

Title	General formula	Different name
			Hexadecylamine	CH 3(CH 2) 14CH 2NH 2	Palmitamide
Octadecylamine	CH 3(CH 2) 16CH 2NH 2	Stearylamine
			Eicosyl amine	CH 3(CH 2) 18CH 2NH 2	Peanut amine
Docosyl amine	CH 3(CH 2) 20CH 2NH 2	Shan Yu amine

The method for preparing cationic surfactant colloidal sol is basic identical with the method that prepare anion surfactant colloidal sol, just with acid substitution alkali, in order to be used for regulating the balance of pH and the electric charge on the increase surfactant granules. When using HCI, suitable pH value is 6.

The printing ink of micro emulsion matrix

The another kind of means that surface tension is sharply descended at a certain temperature threshold place are the printing ink that adopts take micro emulsion as matrix. The phase inversion temperature of selected micro emulsion (PIT) is near the required injection threshold temperature. Below PIT, micro emulsion is the oil (O/W) in the water, and more than PIT, micro emulsion then is the water (W/O) in the oil. When low temperature, the surfactant that consists of micro emulsion forms the deep camber surface that encases oil, and when temperature during apparently higher than PIT, it is surperficial that surfactant then forms the deep camber that encases water. At the temperature place near PIT, micro emulsion forms presses water and the oily continuous ＂ cavernous body ＂ that topological structure connects.

Capillary this decline phenomenon has two kinds of mechanism. Near PIT, surfactant forms the very low surface of curvature, and its curvature is well below the curvature of oil emulsion. So just reduced the surface tension of water. More than phase inversion temperature, micro emulsion has become W/O from O/W, so the interface of printing ink/air has become oil/air from water/air. And the interface of oil/air has lower surface tension.

There are many possible methods to can be used for preparing the printing ink of micro emulsion matrix.

For quick ink-jet, preferably select low viscous oil.

In many examples, water is a kind of suitable polarization solvent. Yet, may need different polarization solvents in some occasion. In these cases, should select to have large capillary polarization solvent, surface tension is sharply descended.

The selection result of surfactant can make phase inversion temperature be within the required scope. For example, can use poly-(oxygen ethene) alkyl phenyl ether (ethoxylated alkyl phenol, general formula is:

C _nH _2n＋1C ₄H ₆(CH ₂CH ₂O)～ _mOH) family. If increase m, just can improve the hydrophily of surfactant, increase n and also can improve hydrophily. Value is approximately 10, and the desired value of n is about 8.

Can prepare the goods of low price with the polymer of the oxirane of various molecule ratios and alkyl phenol, and the accurate quantity of oxyethylene group changes near selected mean value. Goods on these markets just can be satisfied the demand, and do not need to possess the pure surfactant of height of specific quantity oxyethylene group.

The general formula of this surfactant is C₈H _l7C ₄H ₆(CH ₂CH ₂O) _nOH (average n=10).

Synonyms comprises Octoxynol-10, PEG-10 octyl phenyl ether and POE (10) octyl phenyl ether.

HLB is 13.6, and molten point is 7 ℃, and cloud point is 65 ℃.

The goods of this surfactant on market have following brand. In following table, listed the title of supplier and commodity:

Trade name	Supplier
		Akyporox OP100	Chem-Y GmbH
Alkasurf OP-10	Rhone-Poulenc Sufactants and Specialties
		Dehydrophen POP
10	Pulcra SA
		Hyonic OP-10	Henkel Crop.
Iconol OP-10	BASF Crop.
		Igepal O	Rhone-Poulenc France
Macol OP-10	PPG Industries
		Malorphen 810	Huls AG
Nikkol OP-10	Nikko Chem.Co.Ltd.
		Renex 750	ICI Americas Inc.
Rexol 45/10	Hart Chemical Ltd.
		Synperonic OP10	ICI PLC
Teric X10	ICI Australia

These products can be with having bought (each pound is less than one dollar) at a low price in a large number, and therefore, when preparation contained the micro emulsion printing ink of 5% surfactant concentration, each rises only need to be less than 10 cents.

In following table, comprised other applicable ethoxylated alkyl phenol:

Popular name	General formula	HLB	Cloud point
				Nonoxynol-9	C 9H 19C 4H 6(CH 2CH 2O)～ 9OH	13	54℃
Nonoxynol-10	C 9H 19C 4H 6(CH 2CH 2O)～ 10OH	13.2	62℃
				Nonoxynol-11	C 9H 19C 4H 6(CH 2CH 2O)～ 11OH	13.8	72℃
Nonoxynol-12	C 9H 19C 4H 6(CH 2CH 2O)～ 12OH	14.5	81℃
				Octoxynol-9	C 8H 17C 4H 6(CH 2CH 2O)～ 9OH	12.1	61℃
Octoxynol-10	C 8H 17C 4H 6(CH 2CH 2O)～ 10OH	13.6	65℃
				Octoxynol-12	C 8H 17C 4H 6(CH 2CH 2O)～ 12OH	14.6	88℃
Dodoxynol-10	C 12H 25C 4H 6(CH 2CH 2O)～ 10OH	12.6	42℃
				Dodoxynol-11	C 12H 25C 4H 6(CH 2CH 2O)～ 11OH	13.5	56℃
Dodoxynol-14	C 12H 25C 4H 6(CH 2CH 2O)～ 14OH	14.5	87℃

Except capillary control, the printing ink of micro emulsion matrix also has other advantages:

1) micro emulsion is stable at thermodynamics, and can not separate. Therefore, the time of storage can be very long. This point is particularly useful for office and portable printer that those just use once in a while.

2) micro emulsion can be formed naturally the ink droplet of specific size, and does not need to stir thoroughly, and centrifugal or filtration just can guarantee to make the size of oil emulsion ink droplet to be in specific scope.

Therefore 3) contained oil mass can be very high in printing ink, can use oil-soluble or water soluble or dissolve in the two dyestuff. Also can use the dyestuff of mixing, a kind of water soluble, another kind of oil-soluble so just can obtain specific color.

4) can stop the flocculation of oily miscible pigment, because it is to be rolled in the small ink droplet of oil.

5) use micro emulsion can reduce the color of different pigment in the lip-deep mixing of printed medium.

6) viscosity of micro emulsion is very low.

7) can reduce or do not use wetting agent.

Dyestuff and pigment in the micro emulsion matrix printing ink

The mixture of oil-containing can have very high oil content-up to 40%-and still can consist of the micro emulsion of O/W in the water. So just can add a lot of dyestuffs or pigment.

Can use the mixture of dyestuff and pigment. The ink mixture of a routine micro emulsion matrix that comprises dyestuff and pigment is as described below:

1) 70% water

2) 5% the water stain

3) 5% surfactant

4) 10% oil

5) 10% oily miscible pigment

Nine kinds of operational basic combinations that belong to oil phase and the water colouring agent of micro emulsion have been represented in the following table.

Combination	The colouring agent of water	The colouring agent of oil phase
			1	Nothing	The miscible pigment of oil
2	Nothing	Oil-soluble dyes
			3	The water stain	Nothing
4	The water stain	The miscible pigment of oil
			5	The water stain	Oil-soluble dyes
6	The pigment that is dispersed in water	Nothing
			7	The pigment that is dispersed in water	The miscible pigment of oil
8	The pigment that is dispersed in water	Oil-soluble dyes
			9	Nothing	Nothing

Do not have colouring agent in the 9th kind of combination, it can be used for the front cover of print transpatent, UV printing ink, and the signal portion of glazing selectively.

Because many dyestuffs all are amphiphilics, also can dissolve a large amount of dyestuffs in the oil-water boundary layer, because the surface area of this one deck is very large.

Also can use the multiple dyestuff or the pigment that are in various liquid phases, and obtain the dyestuff of various liquid phases and the mixture of pigment.

When using multiple dyestuff and pigment, the absorption spectrum of synthetic ink is the weighted average of the absorption spectrum of used different colorant. Can produce like this two kinds of problems:

1) because the absorption peak of two kinds of colouring agents is averaged, absorption spectrum can trend towards broadening. Can cause like this color ' muddiness ' trend. In order to obtain color true to nature, need to carry out careful selection according to the absorption spectrum of dyestuff and pigment, and be not only the color of selecting human eye to see.

2) color of printing ink may be different on different substrates. If used dyestuff and pigment in combination, if print at the larger paper of absorbability, the color of dyestuff role in the ink colors of printing is less because dyestuff can be inhaled in the paper, pigment then can ' lid ' on paper. This is a kind of advantage in some occasion.

The Krafft point is in the surfactant within the ink droplet selection temperature range

For Ionized surfactant, a temperature (Krafft point) is arranged, below the temperature, its solubility is very low at this, and does not basically comprise colloidal ion in the solution. More than the Krafft temperature, might form colloidal ion, and the solubility of surfactant can increase rapidly. If critical colloidal ion concentration (CMC) has surpassed the solubility of surfactant at a certain temperature, just can be on the point of solubility maximum rather than the CMC point obtain minimum surface tension. The effect of surfactant when the Krafft point is following is normally very low.

This phenomenon can be used for making surface tension along with the increase of temperature further reduces. At ambient temperature, some surfactant in the solution. When nozzle heater was opened, temperature rose, and more surfactant will enter in the solution, and surface tension is reduced.

When the option table surface-active agent, its Krafft point should be near the upper limit of the temperature range of printing ink heating. So just can make concentration and the ink droplet of environment temperature lower surface activating agent in solution select to obtain between the concentration of temperature lower surface activating agent in solution maximum surplus.

The concentration of surfactant should approximate greatly CMC on the Krafft point. Adopt this method, when temperature rises, can farthest reduce surface tension, and make at ambient temperature capillary decline minimum.

Following table has represented that several Krafft points are in the surfactant of the commercialization of ideal range.

General formula	The Krafft point
		C 16H 33SO 3 -Na +	57℃
C 18H 37SO 3 -Na +	70℃
		C 16H 33SO 4 -Na +	45℃
Na +O 4S(CH 2) 16SO 4 -Na +	44.9℃
		K +O 4S(CH 2) 16SO 4 - K +	55℃
C 16H 33CH(CH 3)C 4H 6SO 3 -Na +	60.8℃

Cloud point is in the surfactant within the ink droplet selection temperature range

Adopt the non-ionic surface active agent of polyoxyethylene (POE) chain can be used for making such printing ink, its surface tension reduces along with the increase of temperature. When low temperature, the POE chain is hydrophilic, and surfactant is retained in the solution. When temperature rose, the steeping in water for reconstitution life of constructing around the molecule of POE part was broken, and the POE part has just become hydrophobic. Water can further resist surfactant when high temperature, so that the surfactant concentration on the air/oil China ink interface increases, so just reduced surface tension. It is relevant with the cloud point of surfactant to make the POE of non-ionic surface active agent partly become hydrophilic actual temp. The POE chain itself is not specially suitable, because its cloud point is generally more than 100 ℃.

Polyoxypropylene (POP) can be used to be combined into the POE/POP block copolymer with POE, thereby reduces the cloud point of POE chain, and can not produce very strong hydrophily when low temperature.

Have the POE/POP block copolymer of symmetry of two kinds of primary structures available, they are:

1) have the POE section in the end of molecule, and the surfactant that has the POP section in the centre, for example surfactant of poloxamer level (general designation CAS 9003-11-6).

2) have the POP section in the end of molecule, and the surfactant that has the POE section in the centre, for example surfactant of meroxapol level (also being to be called CAS 9003-11-6).

Listed various poloxamer and the meroxapol that sell in market in following table, they at room temperature have higher surface tension, and its cloud point is more than 40 ℃ and below 100 ℃.

Popular name	The BASF trade name	General formula	Surface tension (mN/m)	Cloud point
					Meroxa pol     105	Pluronic     10R5	HO(CHCH 3CH 2O)～ 7(CH 2CH 2O) ～ 22-(CHCH 3CH 2O)～ 7OH	50.9	69℃
Meroxa pol
	108	Pluronic     10R8	HO(CHCH 3CH 2O)～ 7(CH 2CH 2O) ～ 91-(CHCH 3CH 2O)～ 7OH	54.1	99℃
Meroxa pol     178						Pluronic     17R8	HO(CHCH 3CH 2O)～ 12(CH 2CH 2O) ～ 136-(CHCH 3CH 2O)～ 12OH	47.3	81℃
	Meroxa pol     258	Pluronic     25R8	HO(CHCH 3CH 2O)～ 18(CH 2CH 2O) ～ 163-(CHCH 3CH 2O)～ 18OH	46.1	80℃
Poloxamer     105						Pluronic     L35	HO(CH 2CH 2O)～ 11(CHCH 3CH 2O) ～ 16-(CH 2CH 2O)～ 11OH	48.8	77℃
	Poloxamer     124	Pluronic     L44	HO(CH 2CH 2O)～ 11(CHCH 3CH 2O) ～ 21-(CH 2CH 2O)～ 11OH	45.3	65℃

Adopt known technology also can be easy to synthesize other various poloxamer and meroxapol. Desirable characteristic is to make surface tension at room temperature high as best one can, and cloud point is between 40 ℃ to 100 ℃, preferably 60 ℃ to 80 ℃.

At Meroxapol[HO (CHCH₃CH ₂O) _x(CH ₂CH ₂O) _y(CHCH ₃CH ₂O) _zOH] in the product, the suitable mean value of x and z is 4, and the mean value of y is 15.

If increase the electric conductivity of printing ink with salt, just need to consider the impact of the cloud point of this salt Surfactant.

If break the structure (for example I) of water with ion, just can improve the cloud point of surfactant, because can make so more hydrone and POE oxygen orphan to consisting of hydrogen bond. Utilize to form the water structure ion (for example Cl～, OH～) can reduce the cloud point of POE surfactant, this is less because can consist of the hydrone of hydrogen bond. Bromide ion affect less. By the length that changes POE in the block copolymer surfactant and POP chain can make ink composition in the temperature range of appointment ' change ', and can by change the salt that adds (be CI～to Br～to I～) selection increase electric conductivity. NaCl is being best selection aspect the increase electric conductivity, because it is very cheap and nontoxic. NaCl can make the cloud point of non-ionic surface active agent reduce slightly.

Hot melt printing ink

Printing ink at room temperature not necessarily must be liquid. If printhead and ink storage device are heated on the molten point of printing ink, just can use solid ' hot melt ' printing ink. Hot melt printing ink must be made according to prescription, and the surface tension of dissolving printing ink is reduced along with temperature. The typical reduction amplitude of the goods of many employing waxes and other materials approximately is 2mN/m. Yet when relying on the reduction surface tension rather than reducing viscosity, in order to obtain desirable operation tolerance limit, it should be about 20mN/m that desirable surface tension reduces amplitude.

For hot melt printing ink, static temperature and ink droplet select the temperature difference that the temperature difference between the temperature can be than for water-based inks the time large, because water-based inks is subject to the restriction of the boiling point of water.

Printing ink must be liquid under static temperature. This static temperature should be higher than being printed the high ambient temperature that the page may run into. Simultaneously, static temperature should be low as far as possible, in order to reduce power required when adding thermal printer head, and provides maximum tolerance limit between static temperature and ink droplet injection temperation. The most general static temperature is between 60 ℃ to 90 ℃, although also can adopt other temperature range. The most general ink droplet injection temperation is between 160 ℃ to 200 ℃.

There is following several method to realize and to promote surface tension to reduce along with the rising of temperature.

1) fine granular of dissemination surface activating agent, its molten point is higher than static temperature significantly, but is lower than significantly the ink droplet injection temperation, can under liquid-phase condition it be added hot melt printing ink.

2) a kind of polarization/non-polarised micro emulsion, the molten point that its PIT cans be compared to polarization and non-polarized compound most is high at least 20 ℃.

For surface tension is sharply reduced along with temperature, the carrier of hot melt printing ink should have relatively large surface tension (more than 30mN/m) under static temperature. Typically use for example alkane of wax. Suitable material has very strong intermolecular attraction usually, and this gravitation can be obtained by many hydrogen bonds, polyalcohol for example, and for example, the molten point of Hexanetetrol is 88 ℃.

The surface tension of various solution reduces

Fig. 3 (d) is illustrated in comprise following additive various and contains in the aquatic product temperature effect for stalagmometry:

1) 0.1% octadecanoid acid colloidal sol

2) 0.1% hexadecanoic acid colloidal sol

3) 0.1% Pluronic 10R5 (trade mark of BASF) solution

4) 0.1% Pluronic L35 (trade mark of BASF) solution

5) 0.1% Pluronic L44 (trade mark of BASF) solution

Illustrated to be fit to the printing ink that print system of the present invention is used in following Australian patent specification, these specifications can be used as reference herein:

" based on the ink combination of microemulsion " (Ink composition based ona microemulsion) (application number: PN5223, submit September 6 nineteen ninety-five);

" ink combination that comprises surfactant " (Ink composition containing surfactant sol) (application number: PN5224, submit September 6 nineteen ninety-five);

" near the ink combination of the DOD printer that has Krafft to order selecting temperature at ink droplet " (Ink composition for DOD printers with Krafft point near the drop selection temperture sol) (application number: PN6240, submit October 30 nineteen ninety-five); And

" based on the dyestuff in the microemulsion of printing ink and pigment " (Dye and pigment in a microemulsion based ink) (application number: PN6241, submit October 30 nineteen ninety-five).

Low viscous operation falls in employing

As second example, in following embodiment, reduce viscosity and employing separates ink droplet near mode by heating in combination with hot melt printing ink. Before printer operation, in holder 64, solid ink is dissolved. Printing ink leads to printhead by oil ink passage 75 from holder, and printhead 50 maintained makes printing ink 100 be in liquid state, but the but temperature of relatively high (for example approximately 100cP) of viscosity. Surface tension by printing ink is limited in printing ink 100 within the nozzle. Printing ink 100 is made by prescription, and its viscosity is reduced along with the rising of temperature. Ink pressure is vibrated at certain frequency, and this frequency is the integral multiple of the frequency of spraying in the drops out from nozzles. The pressure oscillation of printing ink is so that be in the printing ink meniscus of nozzle tip and vibrate, but because the viscosity of printing ink is very high, this vibration is very little. Under normal running temperature, the underswing of this vibration is so that the ink droplet separation. When heater 103 was activated, the printing ink that consists of selected ink droplet was heated, and its reduced viscosity is to certain value, and this value is preferably less than 5cP. The reduction of viscosity is moved further the printing ink meniscus during the high pressure section of ink pressure circulation. Recording medium 51 is arranged on the position of fully close printhead 50, makes selected ink droplet touch recording medium 51, but enough far away again, makes unselected ink droplet can not run into recording medium 51. When touching recording medium 51, selected part ink droplet will solidify, and is adsorbed on the recording medium. Along with the decline of ink pressure, printing ink begins to get back in the nozzle. The main body of printing ink is separated with printing ink on being set in recording medium. Then, return to again by a small margin vibration at the meniscus of the printing ink 100 of nozzle tip. Be dispersed into along with remaining heat on the printing ink and printhead of bulk, the viscosity rise of printing ink is to its static level. Each thermal pulse is selected and is separated an ink droplet, and forms a point in recording medium 51. Because thermal pulse just can realize the ink ejection operation mode of throwing in as required by circuit control.

The manufacturing of printhead

The manufacture method of monolithic print head of the present invention has been described in the following Australian patent specification punching of submitting in April 12 nineteen ninety-five, and these specifications can be used as reference herein:

" monolithic LIFT printhead " (A monolithic LIFT printing head) (application number: PN2301);

" manufacture method of monolithic LIFT printhead " (A manufacturing process for monolithic LIFT printing head) (application number: PN2302);

" the auto-collimation design of LIFT printhead " (A self-aligned header design for LIFT print heads) (application number: PN2303);

" integrated four look LIFT printheads " (Integrated four color LIFT print heads) (application number: PN2304);

" reduction of the power requirement in monolithic print head " (Power requirement reduction in monolithic LIFT printing heads) (application number: PN2305);

" manufacture method of employing wet corrosion LIFT printhead " (A manufacturing process for monolithic LIFT print heads using anisotropic wet etching) (application number: PN2306);

" nozzle location in monolithic DOD printhead " (Nozzle placement in monolithic drop-on-demend print heads) (application number: PN2307);

" the heating head structure of monolithic print head " (Heater structure for monolithic LIFT print heads) (application number: PN2346);

" connection of monolithic LIFT printhead power supply " (Power supply connection for monolithic LIFT print heads) (application number: PN2347);

" near the outside connection of LIFT printhead " (External connection for Proximity LIFT print heads) (application number: PN2348); And

" " the auto-collimation manufacture method of monolithic LIFT printhead " (Aself-aligned manufacturing process for monolithic LIFT print heads) (application number: PN2349); And

" the CMOS compatible making method of LIFT printhead " (CMOS process compatible fabrication of LIFT print heads) (application number: PN5222, submit September 6 nineteen ninety-five).

" manufacture method with LIFT printhead of nozzle edge heater " (A manufacturing process for LIFT print heads with nozzle rim heater) (application number: PN6238, submit October 30 nineteen ninety-five);

" module LIFT printhead " (A modular LIFT print head) (application number: PN6237, on October 30th, 1995 submitted);

" increase the method for printing nozzle packed density " (Mothod of increasing packing density of printing nozzle) (application number: PN6236, submit October 30 nineteen ninety-five); And

" nozzle that reduces electrostatic interaction between the isochronous printing ink droplet scatters " (Nozzle dispersion for reduced electrostatic interaction between simultaneously printed droplets)

(application number: PN6239, submit October 30 nineteen ninety-five).

The control of printhead

Described the device of the heter temperature that is used in the present invention providing page-images data and control printhead in the following Australian patent specification of submitting April 12 nineteen ninety-five, these specifications can be used as reference herein:

" integrated drive electronics in the LIFT printhead " (Integrated drive circuitry in LIFT print heads) (application number: PN2295);

" the nozzle cleaning process that is used for liquid ink capacity (LIFT) printing " (A nozzle clearing procedure for Liquid Ink Fault Tolerant (LIFT) printing) (application number: PN2294);

" heater power that is used for LIFT print system temperature compensates " (Heater power compensation fortemperaturein LIFT printing systems) (application number: PN2314);

" heater power that is used for LIFT print system thermo-lag compensates " (Heater power compensation for thermal lag in LIFT printing systems) (application number: PN2315);

" heater power that is used for LIFT print system print density compensates " (Heater power compensation for print denslty in LIFT printing systems) (application number: PN2316);

" the accurate control of printhead temperature pulse " (Accurate control of temperature pulses in printing heads) (application number: PN2317);

" data in the monolithic LIFT printhead distribute " (Data distrbution in monolithic LIFT print heads) (application number: PN2318);

" the page or leaf image and the tolerance route device that are used for the LIFT print system " (Page image and fault tolerance routing device for LIFT printing systems) (application number: PN2319); And

" the removable fluid under pressure ink cartridge of LIFT printer " (A removable pressurized liquidink cartridge for LIFT printers) (application number: PN2320).

The image of printhead is processed

The target of print system of the present invention is to obtain such print quality, and it is equivalent to the quality of the Colorful publishing thing of the habitual use offset printing technology printing of people. Print resolution with about 1600dpi just can obtain this effect. Yet the printing of 1600dpi is that difficulty is expensive again. Print resolution with 800dpi can obtain similar effect, and dark blue and wine-colored each pixel is with 2, and each pixel of yellow and black is with 1. This color mode is referred to herein as CC ' MM ' YK. If also need high-quality monochrome image to print, also can adopt 2 of each pixels to black. This color mode is referred to herein as CC ' MM ' YKK '.

Described the color mode, tone processing, data compression and the real-time extension system that are suitable for system of the present invention and other print systems in the following Australian patent specification of submitting April 12 nineteen ninety-five, these specifications can be used as reference herein:

" the level Four printing ink that is used for the twin-stage colour print " (Four level ink for bi-level color printing) (application number: PN2339);

" compressibility of page or leaf image " (Compression system for page images) (application number: PN2340);

" the real-time extension equipment that is used for the page or leaf image of compression " (Real-time expansion apparatus for compressed page images) (application number: PN2341); And

" document image that is used for the high power capacity compression of digital color printer " (High capacity compressed document image for digital color printers) (application number: PN2342);

" the JPEG compression in the improvement of text " (Improving JPEG compression in the presence of text) (application number: PN2343);

" expansion and the halftoning device that are used for the page or leaf image of compression " (An expansion and halftoning device for compressed pageimages) (application number: PN2344); And

" improvement of image halftoning " (Improvements in image halftoning) (application number: PN2345).

The application of printhead of the present invention

Method of printing of the present invention and device are fit to widely purposes, comprise below (but being not limited only to): colored and monochromatic office printer, the figure punch that uses in short-term, high-speed figure are printed, are processed chromatograp, on-the-spot colour print, the auxiliary low price printer of printing, adopting the scan-type printhead of offset press, adopt high-speed printer, portable colour and monochrome printers, colour and one-color copier, colour and monochromatic facsimile machine, combination printer, fax and duplicator, the label printing machine of pagewidth printhead, large space of a whole page plotter, photocopying, be used for the portable printer of printing machine that Digital photographic processes, the numeral of packing into ' vertical bat ' video camera, with the printer of the printer of display screen, PhotoCD image, for portable printer, wallpaper stripper printing machine, indoor character printer, document printing and the cloth print of ' Personal Digital Assistants '.

Described based on print system of the present invention in the following Australian patent specification of submitting April 12 nineteen ninety-five, these specifications can be used as reference herein:

" the high-speed color office printer with the storage of large capacity digital page or leaf image " (A high speed color office printer with a high capacity digital page image store) (application number: PN2329);

" the in short-term digital color printer with the storage of large capacity digital page or leaf image " (A short run digital color printer with a high capacity digital page image store) (application number: PN2330);

" the color digital compression of use LIFT printing technique " (A digital color printing press using LIFT printing technology) (application number: PN2331);

" compression printed in the modulus word " (A modular digital printing press) (application number: PN2332);

" high-speed figure cloth print " (A high speed digital fabric printer) (application number: PN2333);

" photochrome treatment system " (A color photograph coping system) (application number: PN2334);

" the high-speed color photo duplicator of use LIFT print system " (A high speed color photocopier using a LIFT printing system) (application number: PN2335);

" the portable photochrome duplicator of use LIFT technology " (A protable color photocopier using LIFT printing technology) (application number: PN2336);

" photo processing system of use LIFT printing technique " (A photograph processing system using LIFT printing technology) (application number: PN2337);

" the flat paper facsimile machine of use LIFT print system " (A plain paper facsimile machine using a LIFT printingsystem) (application number: PN2338);

" the photo CD system with integrated printer " (A PhotoCD system with integrated printer) (application number: PN2293);

" color plotter of use LIFT printing technique " (A color plotter using LIFT printing technology) (application number: PN2291);

" notebook with integrated LIFT color printing system " (A notebook computer with integrated LIFT color printing system) (application number: PN2292);

" portable printer of use LIFT print system " (A portable printer using a LIFT printing system) (application number: PN2300);

" facsimile machine with online database and the printing of customization magazine " (Fax machine with on-line database interrogation and customized magazine printing) (application number: PN2299);

" miniature color printer " (Miniature portable color printer) (application number: PN2298);

" color video printer of use LIFT print system " (A color video printer using a LIFT printing system) (application number: PN2296); And

" integrated printer, duplicator, scanner and the facsimile machine of use LIFT print system " (An integrated printer, copier, scanner, and facsimile using a LIFT printing system) (application number: PN2297).

To printing the compensation of headring border condition

The print system of throwing in as required have consistently and predictable droplet size and position. The unnecessary variation of droplet size and position can make the optical density (OD) of print result change, and the print quality of seeing will reduce. These variations should be maintained at minimum ratio in specified droplet volume and pixel gap. Can compensate many environmental variances, in order to its impact is reduced to unconspicuous level. Offer the power of nozzle heater by change, can carry out compensation initiatively to some factor.

The optimum temperature curve that is used for a printhead embodiment is such, namely a flash the chien shih nozzle tip active component rise to injection temperation, at impulse duration this position is maintained injection temperation, and in a flash this position is being cooled to environment temperature.

Because hot memory capacity and the heat conduction property of the various materials that use when making printhead of the present invention, this preferred plan can't realize. Yet, undertaken repeatedly selectedly hand to hand by the finite element model to printhead, just can obtain a curve, utilize this curve sharpening output pulses, so just can improve performance. Can utilize various technology change provides time from power to heater, this comprising, but be not limited in:

1) changes the voltage that is added on the heater

2) width (PWM) of a series of short pulses of modulation

3) frequency (PFM) of a series of short pulses of modulation

In order to obtain accurate result, can simulate the instantaneous hydrodynamic model of Free Surface when needing one in printing ink, to have convection current and ink flow, obtain effective impact of temperature with concrete power curve.

If at the printhead substrate suitable digital circuit is installed, just can controls independently the power that offers each nozzle. A kind of mode of accomplishing this point be on whole print head chip ' broadcasting ' various digit pulse string, and be an amount of train of pulse of each nozzle selection by multiplex electronics.

In the table of ＂ to the compensation ＂ of environmental factor, some environmental factors that can be compensated have been listed. Pointed out that at this table the optimal compensation to each environmental factor is whole (for whole printhead), (for each chip in the synthetic multi-chip printhead) of chip one by one, still nozzle one by one.

＜to the compensation of environmental factor 〉

Compare factor	Scope	Detect or user's control method	Compensation mechanism
				Environment temperature	Whole	Be contained in the temperature sensor on the printhead	Supply voltage or whole PFM figure
Supply voltage changes along with the quantity of effective nozzle	Whole	Predict the quantity of effective nozzle according to print data	Supply voltage or whole PFM figure
				Successively startup generation amount of localized heat along with nozzle	Nozzle one by one	Predict the quantity of effective nozzle according to print data	For each printed dot is selected suitable PFM figure
The size of control ink droplet when each pixel has multidigit	Nozzle one by one	View data	For each printed dot is selected suitable PFM figure
				Nozzle Geometrical change between the wafer	Chip one by one	In factory, measure the data file that offers printhead	The whole PF M figure of print head chip one by one
Heater resistance between the wafer changes	Chip one by one	In factory, measure the data file that offers printhead	The whole PF M figure of print head chip one by one
				The user images Auto-regulating System of Density of Heavy Medium	Whole	User selection	Supply voltage, static accelerating potential, or ink pressure
Reduce method and the threshold temperature of ink surface tension	Whole	Ink cartridge sensor or user selection	Whole PFM figure

Ink viscosity	Whole	Ink cartridge sensor or user selection	Whole PFM figure and/or clock rate
				The dyestuff of printing ink or pigment concentration	Whole	Ink cartridge sensor or user selection	Whole PFM figure
The printing ink response time	Whole	Ink cartridge sensor or user selection	Whole PFM figure

Do not need all of these factors taken together is compensated in most application scenarios. Some variable has negative effect, and only just needs compensation when requiring very high picture quality.

Print-head drive circuit

Fig. 4 is the schematic block diagram according to the circuit theory of a routine print-head drive circuit of the present invention. This control circuit adopts the supply voltage of analog-modulated, provides it to printhead, thereby realizes the heater power modulation, and the not independently control of power to offering each nozzle. Fig. 4 has represented to adopt the system block diagram of 800dpi pagewidth printhead, and this system adopts CC ' MM ' YK color mode to carry out colour print. Printhead 50 has altogether 79,488 nozzles, and 39,744 main burners and 39,744 redundant nozzles are wherein arranged. Main burner and redundant nozzle are divided into six kinds of colors, and every kind of color is divided into 8 driving phases. Each drives a shift register mutually, is used for the serial data from print head controller ASIC 400 is converted to for the parallel data that starts control circuit for heater. Always have 96 shift registers, 828 nozzles of respectively doing for oneself provide data. Each shift register is made of 828 shift register stage 217, and its output is by a ＂ and non-＂ door 215 and phase enabling signal actuating logic ＂ and ＂. The output of NAND gate 215 drives an inverter buffer 216, and the latter controls driving transistors 201 again. Driving transistors 201 excitation electric hot heaters 200, it can be the heater 103 shown in Fig. 1 (b). Effective in order during starting impulse, to keep shifted data, stopped the clock of shift register by clock brake 218, it is effective to keep starting impulse, represents the clock brake with single door in the drawings for clear, but can realize with any known error free clock control circuit. The clock that stops shift register can being locked in parallel data in the printhead, but the circuit among the print head controller ASIC 400 has been increased some complexity. According to the state of special signal on the malfunction bus, data shunt 219 sends to main burner or redundant nozzle to data.

Printhead shown in Fig. 4 is through simplifying, and not have to represent for improvement of various devices such as the parts (block) of manufacturing process are fault-tolerant. Be easy to obtain drive circuit for the different structure printhead according to device disclosed herein.

The digital information that represents the print point figure on the recording medium is stored in page or leaf or the range storage device 1513, and it can be identical with the video memory 72 among Fig. 1 (a). Address multiplexer 417 is read 32 bit data that represent a kind of color dot by address choice from page or leaf or range storage device 1513, and produces control signals by memory interface 418. These addresses are produced by address generator 411, and it is ' part of the circuit of every kind of color ' 410, six kinds of color components respectively have a sort circuit 410. The address is to produce according to the position of nozzle with respect to printed medium. Because the relative position of the nozzle of different printheads might be different, address generator is preferably programmable. Address generator 411 produces the address corresponding with the main burner position when normal. Yet, when breaking down nozzle, in fault graph R AM412, can mark the position of out of order jet element. In printer page, read fault graph RAM412. If this memory indicates fault is arranged in jet element, the address just is changed, the address that makes address generator 411 produce corresponding redundant nozzle location. Lock the data of from page or leaf or range storage device 1513, reading with register 413, and converted thereof into four bytes of order by multiplexer 414. Regulate the sequential of these bytes with FIFO415, make itself and the Data Matching that represents other colors. Then cushion these data by buffer 430, thereby consist of 48 main data bus of printhead 50. Because the position potential range print head controller ASIC of printhead is relatively far away, data need buffering. Also consisted of the input of FIFO416 from the data of fault graph RAM412. The output data of the sequential of these data and FIFO415 are complementary, and by buffer 431 bufferings, thereby consist of the malfunction bus.

Programmable power supply 320 provides electric power for printhead 50. The voltage of power supply 320 is subjected to the control of DAC313, and DAC313 is the part of the combination (RAMDAC) 316 of RAM and DAC. RAMDAC 316 comprises a two-port RAM 317. The content of two-port RAM 317 is by microcontroller 315 programmings. Come compensation temperature by the content that changes two-port RAM 317. These values of temperature computation that microcontroller 315 detects according to heat sensor 300. The signal of heat sensor 300 is connected to analog-digital converter (ADC) 311. ADC 311 preferably is contained within the microcontroller 315.

Print head controller ASIC 400 comprises the control circuit for thermal lag compensation and print density. It is an in time vertiginous voltage that thermal lag compensation requires the supply voltage in printhead Europe 50, and it should be synchronous with the starting impulse of heater. This voltage is by 320 programmings produce to programmable power supply. DAC 313 produces the program voltage that a simulated time changes according to the data of reading from two-port RAM 317. Data are read out according to the address that is produced by counter 403. Counter 403 produces the address of a complete cycle during a starting impulse. Because counter 403 is by system clock 408 regularly, thus guaranteed this synchronously, and the highest counting of counter 403 is used as the timing that starts counter 404. Then by the decoding of the counting of 405 pairs of startup counters 404 of decoder, and produce the starting impulse of printhead 50 through the buffering of buffer 432. If the status number of counting is less than the clock periodicity in the starting impulse, counter 403 can comprise a pre-frequency counter. For the thermo-lag of compensating heater accurately, adopt 16 voltage status. These 16 states can be specified with four connecting lines between counter 403 and the two-port RAM 317. Yet these 16 states not necessarily adopt linear interval in time. In order to satisfy the non-linear timing of these states, counter 403 can also comprise a ROM or other devices, in order to counter 403 is counted according to nonlinear mode. Or also can adopt and be less than 16 status number.

Aspect the print density compensation, in each start-up period, the pixel number of an ink droplet of needs (on pixel) printing is counted, detect thus print density. 402 pairs in print picture element (print pel) counter ' print ' the pixel counting. Eight starting impulses respectively there is a print picture element (print pel) counter 402. According to the present invention, the startup number of phases in printhead depends on concrete design. Although and do not require that the startup number of phases must be two multiple, normally four, eight and 16. Print picture element (print pel) counter 402 can be made of combinational logic pixel counter 420, determines in a data segment how many units to be arranged with counter 420. Then by adder 421 and accumulator 422 cumulative these units. Register 423 keeps this cumulative numerical value effective during starting impulse. Multiplexer 401 is selected the output of the register 423 of corresponding current starting impulse according to the decision that starts counter 404. The output of multiplexer 401 has consisted of a part of address of two-port RAM 317. Do not need right ' print ' pixel counts accurately, only needs four highest significant positions of this counting just enough.

The combination of four thermal lag compensation addresses and four print density compensation addresses represents 8 bit address of dual-port RA M317. This expression two-port RAM 317 comprises 256 numerical value that are arranged in two-dimensional array. This two-dimensional representation (being used for thermal lag compensation) time and print density. Can also comprise the third dimension, namely temperature. Because the variation of ambient temperature of printhead is very slow, microcontroller 315 has time enough to calculate the matrix of 256 numerical value that are used for compensation thermo-lag and print density under current temperature. Microcontroller periodically (for example per second several times) detects current printhead temperature, and calculates this matrix.

The clock of printhead 50 is produced according to system clock 408 by printhead clock generator 407, and by buffer 406 bufferings. For ease of test printing head controller ASIC,

Can also comprise jtag test circuit 499.

Comparison with hot ink-jet technology

The table of comparison ＂ between the hot ink-jet of ＂ and the present invention has been made the comparison of each side to the present invention and thermal inkjet-printing technology.

Because the present invention and hot ink-jet technology all are the as required jettison systems that adopts thermal excitation and liquid ink, can directly compare between the two. Although they look like similarly, these two kinds of technology are by different principle work.

The thermal inkjet-printing technology adopts following basic principle of operation. The thermal pulse that produces by resistance heated forms rapidly bubble in liquid ink. Can be fast and form reliably bubble by making that printing ink is overheated, thus before bubble is assembled fully to the enough heats of printing ink transmission. For water-based inks, the temperature of printing ink need to reach 280 ℃ to 400 ℃. High viscosity inks ink droplet in the pressure wave compressing hole that the formation of bubble causes. Bubble disappears subsequently, and picks up ink from ink storage device is loaded nozzle again. Because the packing density of nozzle is very high, and uses ripe ic manufacturing technology, the thermal inkjet-printing technology has commercially obtained huge success. Yet, the thermal inkjet-printing technology faces like this some obvious technical problems, comprising the yield rate of multipart accurate assembly, device, image resolution ratio, ' difficulty that peppef ' noise, print speed, driving transistors power, power consumption, the splash of formation ink droplet, thermal stress, thermal expansion difference, section a word used for translation oil (kogation), cavitation, distillation diffusion and ink composition cause.

Printing technique of the present invention has many advantages of thermal inkjet-printing technology, and has eliminated the intrinsic many problems of thermal inkjet-printing technology fully or basically.

Comparison between＜hot ink-jet and the present invention 〉

	Hot ink-jet	The present invention
			Ink droplet is selected mechanism	The pressure wave that the bubble that generates by thermoinduction causes sprays ink droplet	Select to reduce the mechanism of surface tension or viscosity
The ink droplet separation mechanism	Select mechanism identical with ink droplet	Select to approach static, magnetic field and additive method
			Basic ink carrier	Water	Water, micro emulsion, alcohol, ethylene glycol, or hot melt
Printhead configuration	Accurately assemble nozzle plate, oil ink passage and substrate	Monolithic
			Every printing expense	Because the life-span of printhead is limited and printing ink is very expensive, expense is very high	Because the durability of printhead and the printing ink that adapts to wide region, expense can reduce
The formation of ink droplet splash	Affect significantly picture quality	Can not form the ink droplet splash

The operating temperature of printing ink	280 ℃ to 400 ℃ (high temperature limit use and the ink composition of dyestuff)	About 70 ℃ (depending on ink composition)
			The heater peak temperature	400 ℃ to 1000 ℃ (high temperature can reduce device lifetime)	About 130 ℃
Air pocket (heater is owing to breaking of bubble worn and torn)	The serious problems of restriction print head longevity	There is not (not forming bubble)
			Section's a word used for translation oil (kogation) (heater is covered by the printing ink ash)	The serious problems of restriction print head longevity and ink composition	There is not (temperature of water-based inks is no more than 100 ℃)
Distillation diffusion (because pressures cycle forms bubbles of ink)	The serious problems of restriction ink composition	Because ink pressure can not become negative value, does not have this problem
			Resonance	The serious problems of limits nozzle structure and repetition rate	Affect very little because pressure wave is very little
True resolution	Maximum is about 800dpi	Maximum is about 1600dpi
			From the cooling operation	There is not (needing high-energy)	Have: the printing ink of printing has been taken away ink droplet and has been selected energy
Ink ejection velocity	High (approximately 10m/sec)	Low (approximately 1m/sec)
			Disturb	Serious problems need accurate acoustic construction, the speed that limits nozzle refills	Low speed, and the pressure when spraying ink droplet is low, therefore disturbs very little
The operation thermal stress	The serious problems of restriction print head longevity	Low: the maximum temperaturerise of heater center approximately is 90 ℃
			Make thermal stress	The serious problems of restriction printhead size	Identical with the CMOS manufacturing process of standard
Ink droplet is selected energy	About 20 μ J	About 270nJ
			The heater pulse cycle	About 2-3 μ s	About 15-30 μ s

The heater pulse mean power	About 8 watts of each heater	The about 12mW of each heater, the specific heat ink-jet is low more than 500 times
			Heater pulse voltage	About 40V	About 5-10V
Heater peak pulse electric current	Each heater needs 200mA usually, needs bipolar or very large MOS driving transistors	The about 4m A of each heater can use little MO S driving transistors
			Fault-tolerant	Do not implement	Implement easily, can make yield rate and Reliability Enhancement
Restriction to ink composition	Comprise section a word used for translation oil (kogation), many restrictions such as unclean	The temperature coefficient of surface tension or viscosity must be negative value
			Ink pressure	Below the atmospheric pressure	About 1.1atm
Integrated drive electronics	Because drive current is large, usually needs bipolar circuit	CMOS, nMOS, or bipolar circuit
			Thermal expansion difference	Obvious problem to large-scale printhead	Structure with monolithic reduces this problem
The pagewidth printhead	Subject matter is yield rate, cost, structure precision, print head longevity, and power consumption	By fault-tolerant acquisition high finished product rate, low cost. Because low-power consumption can cooling itself.

Yield rate and fault-tolerant

As a rule, if monolithic integrated optical circuit function imperfection during fabrication can't be repaired. The percentage of the operational device that produces by wafer process is called as yield rate. Yield rate has direct impact to manufacturing cost. The manufacturing cost of the device of 5% yield rate is than expensive ten times of the manufacturing costs of the identity unit with 50% yield rate.

Here mainly contain three kinds of yield rate measurement indexes:

1) fabrication yield

2) wafer separation yield rate

3) final test yield rate

For the situation of large form, the wafer separation yield rate is normally to the strictest restriction of total yield rate. It is very large comparing with typical VLSI circuit according to full pagewidth color print head of the present invention. Satisfied wafer separation yield rate is crucial problem to effective manufacturing cost of this printhead.

Fig. 5 is for the wafer separation yield rate of the colored A4 printhead of the full pagewidth of monolithic of the present invention embodiment and the relation curve of defect concentration. Printhead has 215mm long and 5mm is wide. Be to calculate according to the method for Murphy without fault-tolerant yield rate 198, this is a kind of yield prediction method of extensive use. If defect concentration is defective of every square of cm, the yield rate that dopes with the method for Murphy is less than 1%. This means that the printhead of making has more than 99% must be abandoned. Low like this yield rate is very undesirable, because the manufacturing cost of printhead is too high.

The method of Murphy is similar to the impact of uneven distribution defective. Fig. 5 also comprises one without the curve of fault-tolerant yield rate 197, and it has introduced a defective grouping coefficient, thereby is clearly shown that the grouping of defective. Defective grouping coefficient be not one during fabrication can be controlled parameter, but can be used as a feature of manufacturing process. The coefficient that defective can be divided into groups in manufacturing process is predefined for 2, and in this case, the perspective view of yield rate roughly conforms to the method for Murphy.

A method that solves low yield rate problem is that introducing is fault-tolerant, namely comprises redundant functional unit at chip, is used for replacing the functional unit of fault.

In integrated circuit (WSI) device of memory chip and most of wafer-scales, the physical location of redundant pair unit on chip is unimportant. Yet in printhead, redundant pair unit may comprise one or more printing starter. The page that they are printed with respect to needs must have fixing spatial relationship. In order to print a point at same position as out of order driver, redundant driver must not misplace in non-scanning direction. Yet failed drive can be replaced by the redundant drive that misplaces in the scanning direction. In order to guarantee that redundant drive can print a point at same position as failed drive,

Can change the data timing of redundant drive, thus the dislocation on the compensated scanning direction.

In order to replace all nozzles, a complete cover nozzle must be arranged, so just consisted of 100% redundancy. Yet the requirement of 100% redundancy need to make chip area double usually, is replacing can reducing significantly elementary yield rate before the redundancy unit, and will offset so fault-tolerant most of advantage of bringing.

Yet, according to printhead embodiment of the present invention, the minimum physical size of print head chip depends on the pagewidth that is printed, and print head chip holds breakable character, and the manufacturing process restriction that runs into when chip provides the oil ink passage of printing ink behind in assembling. The actual minimum dimension that is used for the full duration full color printhead of the printing A4 size page approximately is 215mm^*5mm. When adopting 1.5 μ m CMOS manufacturing technology, this size allows to hold 100% redundancy, and can not increase significantly chip area. Therefore, under the condition that can obviously not reduce elementary yield rate, can realize high-caliber fault-tolerant.

When comprising in the device when fault-tolerant, can not adopt the yield formula of standard. Otherwise in yield formula, must embody particularly and comprise fault-tolerant mechanism and degree. Fig. 5 has represented to be used for the fault-tolerant sorting yield rate of the colored A4 printhead of full page face, comprising various forms of fault-tolerant, has comprised its model in yield formula. This curve represents concrete yield rate with the function of defect concentration and defective grouping. The yield rate perspective view that represents in Fig. 5 shows, under identical creating conditions, adopts fully fault-tolerant networks can make the wafer separation yield rate from bringing up to more than 90% below 1%. Can make like this manufacturing cost reduce by 100 times.

For the printhead that comprises thousands of printing nozzles, fault-tolerantly can improve widely yield rate and reliability, thus just can the actual printhead of making pagewidth. But fault-tolerant is not core content of the present invention.

Described in the fault-toleranr technique of throwing in as required in the print system in the following Australian patent specification of submitting April 12 nineteen ninety-five, these specifications can be used as reference herein:

" the integrated tolerance in printing mechanism " (Integrated fault tolerance in printing mechanisms) (application number: PN2324);

" component tolerances in the integrated print head " (Block fault tolerance in integrated printing heads) (application number: PN2325);

" nozzle that is used for integrated print head tolerance copies " (Nozzle duplication for fault tolerance in integrated printing heads) (application number: PN2326);

" detection of defective nozzle in the printhead " (Detection of faulty nozzles in printing heads) (application number: PN2327); And

" tolerance of large capacity force of impression " (Fault tolerance in high volume printing presses) (application number: PN2328).

Print system embodiment

In Fig. 6, represented to adopt the schematic diagram of a kind of digital and electronic print system of printhead of the present invention. The figure shows a monolithic print head 50, it is printed on the piece image 60 that is made of many ink droplets on the recording medium 51. Typical media are paper, also can be that common transparent film, fabric or many other can be admitted the planar materials of printing ink. Printed image is provided by an image source 52, and it can be any image format that can convert two-dimensional pixel array to. Typical image source has the image of image analyzer, stored digital, the image of using PDL (PDL) to encode, Adobe Postscript for example, Adobe Postscript level2, or Hewlett-Packard PCL 5, the page-images of utilizing raster generator to produce by routine call, Apple QuickDraw for example, Apple Quickdraw GX, or Microsoft is GDI, or the text of electronic form ASCII for example. This view data is converted to the two-dimensional pixel array that is fit to specific print system by image processing system 53. Image can be colored or monochromatic, and each pixel can have the data between 1 to 32 usually, depends on the form of image source and concrete print system. If image source is a kind of page figure, image processing system can adopt raster image processor (RIP), if image source also can adopt the two dimensional image treatment system from a scanner.

If need the image of continuous tone, just need a halftone process system 54. Suitable halftone process mode is based on that ＂ sequentially trembles or the spaced point of error diffusion (dispersed dot ordered dither or error diffusion) ＂. Or adopt known ＂ random screening or frequency modulation(PFM) to screen (stochastic screening or frequency modulation screening) ＂. The boundling point that ＂ when here recommend adoption is not generally used for hectographic printing sequentially trembles (clustered dot ordered dither) " the halftone process system because adopt this technology can unnecessarily waste effective image resolution ratio. The output of halftone process system is binary system monochrome or the coloured image that is fit to the resolution ratio of print system of the present invention.

Binary picture is to be processed by data phasing circuit 55 (it can be contained among the print head controller ASIC 400 shown in Figure 4), and data phasing circuit 55 offers data shift register 56 to pixel data according to correct order. For the arrangement of compensating jet and the movement of paper, need to be to the data sequencing. After data were loaded in the shift register 56, data were provided for heater drive circuit 57 in parallel mode. Drive circuit 57 is connected to corresponding heater 58 potential pulse that produces by pulse shaper 61 and voltage regulator 62 according to correct time with electronic circuit. The tip of heater 58 heated nozzles 59 affects the physical characteristic of printing ink. Ink droplet 60 breaks away from nozzle according to the figure corresponding with the digit pulse that offers heater drive circuit. Ink pressure in the ink storage device 64 is regulated by pressure regulator 63. By selected ink droplet separator ink droplet chosen in the ink droplet 60 is separated from the printing ink main body, and touch recording medium 51. During printing, utilize paper induction system 65 to make recording medium 51 mobile continuously with respect to printhead 50. If printhead 50 has covered the whole width of the print range of recording medium 51, recording medium 51 only needs to move in one direction printhead 50 then can keep fixing. If use less printhead 50, just need to adopt raster scanning system. Typical method is the minor face scanning and printing head 50 along recording medium 51, simultaneously along its long limit moving recording media 51.

Binary picture is to be processed by data phasing circuit 55 (it can be contained among the print head controller ASIC 400 shown in Figure 4), and data phasing circuit 55 offers data shift register 56 to pixel data according to correct order. For the arrangement of compensating jet and the movement of paper, need to be to the data sequencing. After data were loaded in the shift register 56, data were provided for heater drive circuit 57 in parallel mode. Drive circuit 57 is connected to corresponding heater 58 potential pulse that produces by pulse shaper 61 and voltage regulator 62 according to correct time with electronic circuit. The tip of heater 58 heated nozzles 59 affects the physical characteristic of printing ink. Ink droplet 60 breaks away from nozzle according to the figure corresponding with the digit pulse that offers heater drive circuit. Ink pressure in the ink storage device 64 is regulated by pressure regulator 63. By selected ink droplet separator ink droplet chosen in the ink droplet 60 is separated from the printing ink main body, and touch recording medium 51. During printing, utilize paper induction system 65 to make recording medium 51 mobile continuously with respect to printhead 50. If printhead 50 has covered the whole width of the print range of recording medium 51, recording medium 51 only needs to move in one direction printhead 50 then can keep fixing. If use less printhead 50, just need to adopt raster scanning system. Typical method is the minor face scanning and printing head 50 along recording medium 51, simultaneously along its long limit moving recording media 51.

The computer simulation of nozzle dynamic characteristic

Utilize computer that the details of operation of printhead has been made comprehensive simulation. Fig. 7 to 9 is some results of simulation, and the operation of this nozzle is to reduce surface tension by electrical heating to select ink droplet, and combines with the ink droplet separate mode of static.

The characteristic of the phenomenon of observation is extremely useful to determining to be difficult to directly in computer simulation. Owing to following several reasons, the operation of nozzle is difficult to observe by experiment, and these reasons comprise:

1) nozzle of experiment is miniature, and the feature of important phenomenon is less than 1 μ m.

The time scale of 2) spraying ink droplet only has several microseconds, needs high observation speed.

3) important phenomenon occurs in opaque inside of solid material, can not directly observe.

4) for example heat flow and fluid velocity vector field are difficult to directly observe with any scale some important parameters.

5) expense of manufacturing experiment nozzle is very high.

Computer simulation has overcome above-mentioned problem. The software kit that is used for a kind of advanced person of fluid dynamic simulation is Fluid Dynamics International Inc.ofIllinois, the FIDAP that USA (FDI) makes. FIDAP is the registration mark of FDI. On market, also can obtain other simulation softwards, but why select FIDAP to be because it at the fluid dynamic simulation of transition, energy shifts, and the aspect such as surface tension calculating has very high precision. The FIDAP version that adopts is FIDAP7.06.

The theoretical foundation of calculating

In the FIDAP 7.0 Thoery Manual (in April, 1993) that FDI publishes, describe the theoretical foundation that adopts Finite Element Mothod to carry out hydrodynamic analysis and power conversion calculating in detail, and the method for in the FIDAP computer program, using this theoretical foundation, foregoing can be used as reference of the present invention.

Material behavior

The table that is used for the material behavior ＂ of FIDAP simulation at ＂ has provided the approximate physical characteristic of material, and these materials can be used to make printhead.

In fact the character of the ＂ printing ink ＂ that uses in this simulation be exactly the character of pure water. Separate for ink droplet, this is the situation of the worst ＂ of ＂, and the surface tension of printing ink is along with temperature only can reduce slightly. If use surface tension along with the printing ink of the special composition of temperature decrease, just can obtain the opereating specification much wide.

For with the transient state Free-surface model of FIDAP7.06 according to the time acquisition convergence of micron-sized surface tension variations and Microsecond grade, need to adopt nondimensional simulation.

The table that is used for the material behavior ＂ of FIDAP simulation at ＂ has provided the numerical value that uses in the simulation of adopting the FIDAP program. Most of numerical value are taken from CRC Handbook of Chemistry and Physics, 72nd edition, or the handbook of chemistry of Lange, 14th edition.

＜be used for the material behavior of FIDAP simulation 〉

Characteristic		Physical quantity (SI unit)	Dimensionless numerical value
				Characteristic length (L)	All	10-6m	1
Characteristic velocity (U)	Printing ink	1m/s	1
				Characteristic time	All	10-6s	1
Time period	All	10-7s	0.1
				Environment temperature	All	303.15°K	30
Boiling point	Printing ink	376.15°K	103
				The energy density scale factor	Heater	4.216×10 14m	668
Viscosity (η)	At 20 ℃	10.02×10 -4Pas	1.536
					At 30 ℃	7.977×10 -4Pas	1.416
	At 40 ℃	6.534×10 -4Pas	1
					At 50 ℃	5.470×10 -4Pas	0.837
	At 60 ℃	4.665×10 -4Pas	0.714
					At 70 ℃	4.040×10 -4Pas	0.618

	At 100 ℃	2.818×10 -4Pas	0.431
				Surface tension (γ)	At 20 ℃	0.0728Nm -1	111.4
	At 30 ℃	0.0712Nm -1	108.9
					At 40 ℃	0.0696Nm -1	106.5
	At 50 ℃	0.0679Nm -1	103.9
					At 60 ℃	0.0662Nm -1	101.3
	At 70 ℃	0.0645Nm -1	98.7
					At 100 ℃	0.0589Nm -1	90.1
Surface tension coefficient (γ T)	At 40 ℃	0.0728Nm -1k -1	-1.7×10 -4
				Pressure (P)	Printing ink	10,000Pa	15.3
Thermal conductivity (k)	Printing ink	0.631Wm -1k -1	1
					Silicon metal	148Wm -1k -1	234.5
	Amorphous SiO2	1.5Wm -1k -1	2.377
					TaAl	23Wm -1k -1	36.45
	Tantalum	57.5Wm -1k -1	91.13
					Si 3N 4	19Wm -1k -1	30.11
Concrete heat (cp)	Printing ink	3,727Jkg -1k -1	3.8593
					Silicon metal	711Jkg -1k -1	0.7362
	Amorphous SiO2	738Jkg -1k -1	0.7642
					TaAl	250Jkg -1k -1	0.2589
	Tantalum	138Jkg -1k -1	0.1429
					Si 3N 4	712Jkg -1k -1	0.7373
Density (p)	Printing ink	1,036kgm -3	1.5856
					Silicon metal	2,320kgm -3	3.551
	Amorphous SiO2	2,190kgm -3	3.352
					TaAl	10,500kgm -3	16.07
	Tantalum	16,600kgm -3	25.41
					Si 3N 4	3,160kgm -3	4.836

Hydrodynamic analogy

Fig. 7 is temperature curve on from nozzle edge radial finger to the curved surface at printing ink meniscus center in according to a nozzle of printing operate of the present invention. The unit of the longitudinal axis is 100 ℃, and the unit of transverse axis is 10 μ m. At the time phase that is marked as 5 μ s, approximately be 10 μ m along the distance of meniscus radius, and temperature is 30 ℃. During the heater-driven cycle (curves from 10 μ s to 20 μ s), the temperature of nozzle tip (coordinate 0.0) approximately is 100 ℃. The temperature at meniscus center rises to about 60 ℃. Along with printing ink overflows from nozzle, the curved surface from nozzle tip to the meniscus center is gradually elongated. Turn-off (at times 24 μ s) afterwards at heater, the drop in temperature of nozzle tip. Printing ink still continues to overflow from nozzle. At 75 μ s constantly, the nearly 40 μ m of the meniscus radius from nozzle tip to the meniscus center are long.

In 8 (j), represented thermodynamics and the hydrodynamic analogy curve that a routine nozzle makes up at Fig. 8 (a) in each time period. Because this routine nozzle is columnar, adopts axisymmetric analog form. The shape of cylinder can produce four kinds of deviations. Here it is and being connected of heater, because the laminar airflow that the movement of paper causes, gravity (if printhead is not vertical), and the adjacent nozzle that exists on the substrate. These factors are very little on the impact that ink droplet sprays. Spout radius is 7 μ m, and curve adopts corresponding scale.

The tip region that has only represented nozzle is because select relevant most of phenomenons all to appear at this zone with ink droplet. These curves have represented from the nozzle cross-section of the outside 22.1 μ m distances of symmetry axis.

The nozzle that Fig. 8 (a) expression remains static, the surface tension of this moment and ink pressure and exterior static or magnetic field consist of balance. In this figure, the 100th, printing ink, the 101st, silicon chip, the 102nd, silica, the position of 103 expression heaters, the 104th, tantalum passivation layer, the 108th, silicon nitride passivation. Be provided with hydrophobic coating at the silicon nitride passivation that exposes. Nozzle tip and printing ink are in the environment temperature of device, are 30 ℃ herein. During operation, owing to can reach an equilibrium temperature that depends on print density during spraying many ink droplets, the device environment temperature can a little higher than atmospheric temperature. Because the thermal conductivity of silicon is very high, and the convection current in the printing ink, the heat between ink droplet sprays in nozzle distributes very equably.

Nozzle after Fig. 8 (b) expression heater-driven cycle begins during 2 μ s. This is a warm-up phase, for reducing being the required peak power of realization fast temperature transition. The power that offers at this moment heater is 61mW. Temperature isopleth shown in the figure is since 35 ℃ (marks), and increases by 5 ℃ interval.

Nozzle after Fig. 8 (c) expression heater-driven cycle begins during 4 μ s. Apply at this moment peak value heater power (97mW), in printing ink, produce rapid temperature transient.

Nozzle after Fig. 8 (d) expression heater-driven cycle begins during 9 μ s. Heater power is 43mW, so that printing ink, the temperature on the circle interface between nozzle and the air just maintains the boiling point of printing ink following (approximately be 100 ℃ to water-based inks). The figure shows convection current and promptly heat has been taken to the center of meniscus.

Nozzle after Fig. 8 (e) expression heater-driven cycle begins during 14 μ s. Heater power is 40mW. Whole meniscus is heated, and printing ink has begun to flow.

Nozzle after Fig. 8 (f) expression heater turn-offs during 1 μ s. The heater pulse width that adopts in this simulation is 18 μ s, and the heater pulse energy is 930nJ.

Nozzle after Fig. 8 (g) expression heater turn-offs during 16 μ s. This figure demonstrates substrate and is cooled off rapidly, and this moment maximum temperature (56.6 ℃) in printing ink. At this one-phase, printing ink has enough momentum, guarantees that sagging ink droplet can be by inlet nozzle again.

Nozzle after Fig. 8 (h) expression heater turn-offs during 36 μ s. The temperature that this figure demonstrates rising is dispersed into around the meniscus of ink drop very equably, and the temperature of nozzle tip has dropped to 35 ℃.

Nozzle after Fig. 8 (i) expression heater turn-offs during 46 μ s. Taken away by ink drop by most of heat that heater provides. At this one-phase, the temperature of all nozzles has all dropped to below 35 ℃.

Nozzle after Fig. 8 (j) expression heater turn-offs during 56 μ s. The printing ink of nozzle tip has begun ＂ and has shunk ＂, and will form the ink droplet of separation.

If adopt the non-overlapped ink droplet of eight 18 μ s duration to spray phase, total ink droplet spraying cycle is 144 μ s. This has just had time enough that the heat in this structure is distributed by silicon chip and printing ink, thereby does not have obvious interference between the ink droplet of order.

Fig. 9 is meniscus position in the nozzle and the relation curve of time. The unit of the longitudinal axis is 10 μ m, and the unit of transverse axis is 100 μ s. In this simulation, initial meniscus position and resting position are slightly different, and do not have temperature pulse. This curve has represented the degree of resonant frequency (approximately 25KHz can get from the distance derivation between the peak value of order) and meniscus and the decay of printing ink post. Can be clear that from this curve meniscus is promptly got back to resting position, be ready to spray next ink droplet.

The fluid nozzle Dynamic Simulation

Printhead can be designed to operate under very wide condition and range and various print resolution. The most print system of throwing in as required has print resolution between 300 to 400dpi in the market. This point is not an absolute restriction for hot ink discharge device, and still, along with the increase of print resolution, the design of printhead can become more difficult usually gradually. The design of printhead can realize the print resolution of wide region, but the resolution ratio of most products is in 400dpi between the 800dpi. Print main suitable text and figure double-deck time of 400dpi, but can not be applicable to the high-quality panchromatic photography copies. An exception of this situation is the printing on fabric, and can obtain the very standard fabric of high-quality this moment that is printed on of 400dpi. This is because when fabric adopts the mechanical printing technology, be to be difficult to stop fabric to occur between the shades of colour to stretch and distortion printing to the major limitation of print quality. 800dpi is regarded as the peak demand of popular print system, because the result who adopts 800dpi6 look CC ' MM ' YK printing of random screening to produce is about as much as the quality that usefulness 133 to the 1501pi colored hectographic printings of people's custom obtain.

Various nozzles have been carried out a large amount of simulations. Figure 10 (a) has represented to be 400dpi, the comprehensive simulation result of the nozzle of 600dpi and 800dpi printed design to 10 (f). Hydrodynamic analogy is to adopt the FIDAP simulation softward to carry out. Simulation in the various situations all is to carry out during 100 μ s by the interval of 0.1 μ s. Nozzle tip is columnar, and the radius that is used for the 400dpi simulation is 20 μ m, and the radius of 600dpi simulation is 14 μ m, and the radius of 800dpi simulation is 10 μ m. The ink pressure of 400dpi simulation is 3.85KPa, and the ink pressure of 600dpi simulation is 5.5KPa, and the ink pressure of 800dpi simulation is 7.7KPa. Environment temperature in three kinds of simulations all is 30 ℃. When the simulation beginning, the printing ink meniscus is near its resting position, and all speed are zero. Provide the output pulses that changes by the time to heater during since 20 μ s. The pulse duration that is used for the 400dpi simulation is 30 μ s, and the pulse duration that is used for the 600dpi simulation is 24 μ s, and the pulse duration that is used for the 800dpi simulation is 18 μ s. In order to make the printing ink meniscus arrive resting position before the ink droplet strobe pulse, pulse is during since 20 μ s.

In these simulations, only imitated the ink droplet selection course. The ink droplet separation process can be adopted approaching, static, or other devices. Select ink droplet and depend on the physical differences on meniscus position between selected ink droplet and the non-selected ink droplet separating of non-selected ink droplet. In order to realize that ink droplet separates, before the ink droplet strobe pulse, after, the suitable axial difference that adopts 15 μ m between the meniscus center.

Figure 10 (a), 10 (c) and 10 (e) are respectively for the 400dpi nozzle, the meniscus center of 600dpi nozzle and 800dpi nozzle and the relation curve of time. The unit of the longitudinal axis is 10 μ m, and the unit of transverse axis is 100 μ s. When these curves of observation and comparison, need to consider the variation of vertical scale between the curve. Most important feature is that meniscus position can reach about 15 μ m from resting position (position of pulse before 20 μ s beginning). In this, ink droplet separator (not having expression in simulation) can guarantee to make selected ink droplet to separate from the printing ink main body, and is transferred on the recording medium. After the ink droplet strobe pulse, the vibration of meniscus position has just disappeared, and this is because the ink droplet that oozes out has aspheric nature at first: ink droplet becomes oblate ellipsoid shape again from initial prolate ellipsoid deformation globulate, repeatedly vibration between this. These vibrations are unimportant, and this is because the ink droplet separator has become the main determining factor of printing ink meniscus position after ink droplet is selected.

Figure 10 (b), 10 (d) and 10 (f) they are respectively the 400dpi nozzles, the meniscus shape of 600dpi nozzle and 800dpi nozzle is at each instantaneous figure. In order directly to compare, three figures adopt identical scale. During since 20 μ s place ink droplet strobe pulses, until after the end-of-pulsing 4 μ s places for extremely, according to the time interval meniscus position of 2 μ s.

At Figure 10 (b), among 10 (d) and 10 (f), the 100th, printing ink, the 101st, silicon chip, the 102nd, SiO₂, the position of 103 expression ring heaters, one side, the 108th, Si₃N ₄Passivation layer,

The 109th, hydrophobic face coat. Although the title of figure is ＂ temperature Contour map ＂, do not represent the temperature isopleth.

From the analog result of Figure 10 as seen, the structure of nozzle and Fig. 7,8 is different with 9 nozzle analog result. The nozzle of printhead can have many possible structures. Because it is simple that the requirement of the basic demand specific heat inkjet nozzle of nozzle is wanted, the concrete geometry that nozzle can be selected mainly is that the facility according to manufacture craft decides.

Heat drives the certainly cooling operation in the printhead

The invention provides a kind of system that used heat distributes problem of eliminating or obviously reduce, allow printhead to reach higher speed, less size, lower cost, and comprise more nozzle.

This system depends on the printing ink of ejection itself and takes away used heat, and makes the structure of printhead satisfy following two conditions:

1) stationary power consumption (the printhead power consumption when not beginning to print) should be enough low, in order to utilize convection current or the compulsory air-cooled static heat that distributes.

2) maximum drive power consumption (power consumption during printing) should be lower than the ink temperature that is used in printing and rises to the above needed power of reliable operating temperature.

First condition can satisfy with the CMOS drive circuit. Under most of environment, adopt the CMOS drive circuit can make stationary power very low, do not need radiator or other special constructions just can dispel the heat. Bipolarity nMOS or other drive circuits also can use, and just require the thermal impedance from the printhead to the surrounding environment enough low, in order to stop the progressively accumulation of heat. Yet the required driving power of existing hot ink-jet (TIJ) print system is too high, in fact can not adopt CMOS or nMOS circuit. Therefore typically use the bipolar drive circuit. Adopt the printhead of printing technique of the present invention can be designed to have enough low driving power consumption (be lower than TIJ 1%), thus can actual employing CMOS drive circuit.

Second condition can satisfy with the structure of print-head nozzle, is lower than the printing ink of equal volume is heated to the needed energy of the highest ink temperature of keeping reliable printing from the ink environment temperature so that spray the required energy of single ink droplet. If can realize this point, all driving powers can be distributed by the printing ink itself of printing.

The consumption of driving power directly is directly proportional with the ink drop quantity of printing in the time per unit. The power that can distribute in pad-ink also is to be directly proportional with the ink drop quantity printed in the time per unit. Therefore, if the energy of each ink droplet can be reduced to below the thresholding of requirement, just can eliminate power fully and distribute print speed, the restriction that nozzle quantity or spray nozzle density bring, and realize that ＂ is from cooling operation ＂.

Self cooled threshold value depends on environment temperature, ink droplet radius, the actual thermal capacity of printing ink, the boiling point of printing ink, and required opereating specification.

Figure 19 keeps the maximum ink droplet that allows from the cooling operation to spray energy curve. This maximum ink droplet sprays energy curve and draws with respect to ink droplet radius and environment temperature for water-based inks. The opereating specification of supposing is 20 ℃. In hypothesis, ignored the stationary power consumption of printhead.

The printhead that ink droplet injection energy is lower than curve shown in Figure 6 can adopt self cooled mode of operation. Energy shown in Figure 19 is high if printhead sprays the needed energy Ratios of ink droplet, just can not only cool off fully by the ink drop of spraying.

The required ink droplet injection energy of thermal inkjet-printing technology at present general on the market approximately is from ten times that cool off operating threshold. During less than 10pl, thermal ink jet printers is difficult to realize from the cooling operation in the ink droplet model.

Yet the print-head nozzle that operates according to the present invention is easy to realize from the cooling operation.

Adopt the preferred embodiment that reduces the viscosity selection mode

The device of the ink droplet of select to need printing in the present embodiment, is the viscosity that reduces printing ink when having the ink pressure of vibration by heating. The average pressure of the ink pressure of vibration is not enough to overcome the surface tension of printing ink, therefore printing ink is sprayed from nozzle. At ambient temperature, ink viscosity has such value, so that the printing ink meniscus oscillation deficiency that the vibration in the ink pressure causes is so that the ink droplet separation. When the hot driver of nozzle was driven, ink viscosity reduced fully, and the printing ink meniscus oscillation amplitude that the vibration in the ink pressure is caused is enough to cause ink droplet to separate.

In most of the cases, the speed of printing ink is not sufficient to make the ink drop of overflowing to separate from the printing ink main body when it overflows from nozzle. For the most of ink droplet models that in computer-controlled print system, run into, act on that gravity on the ink droplet is compared with surface tension and not obvious, therefore can not be with gravity as the means of separating ink droplet.

Therefore, need to there be a device that selected ink droplet is separated from the printing ink main body, and guarantees that selected ink droplet can form a point in recording medium. The ink drop separator can be selected from following catalogue, but is not limited only to following means:

1) near (making recording medium proximity printing head)

2) electrostatic attraction

3) magnetic field suction

For effectively operation, the viscosity of printing ink should sharply reduce along with temperature. For non-selected ink droplet, ink viscosity should be very high (preferably surpassing 20cP), but then should reduce by the coefficient more than 10 times for selected ink droplet. Adopt various organic waxes, acid, alcohol, the mixture of oil and other compounds can obtain suitable ink characteristics.

Using hot melt printing technique, printing ink according to stickiness printing of the present invention at room temperature is solid. The molten point of printing ink preferably is higher than 60 ℃, also can be made of the compound with different molten points, in order to make its ＂ soften ＂, but does not have special molten point. Before printing, ink storage device and printhead are heated to molten of printing ink more than the temperature (for example 80 ℃). This temperature is used as static temperature. The temperature of printhead can be regulated, in order to reduce environment temperature to the impact of print characteristic.

When needs are printed an ink droplet, just drive an electric heating driver in the nozzle, the ink temperature of nozzle tip is raise. Suitable injection temperation can be higher 100 ℃ than static temperature, in order to enough temperature official post viscosity decreases are arranged. Under the print conditions of high speed, high resolution, the viscosity of printing ink under injection temperation should be lower than 10cP, preferably is in the order of magnitude of 1cP. The reduction of viscosity is so that printing ink is mobile quickly under the ink pressure effect of vibration, thereby printing ink is moved further.

The reduction of viscosity makes selected ink droplet have the meniscus position of peak value, and this position further stretches out from nozzle than the peak value meniscus position of non-selected ink droplet. So just make the ink droplet separator can identify the selected non-selected ink droplet of ink droplet Buddhist monk.

Printing ink is applied the ink pressure that sound wave can obtain to vibrate. Its waveform is restriction not, but adopts sine wave herein, because its easiest control and prediction. Its frequency is identical with the drop ejection frequency of single-nozzle, or its integral multiple. The phase place of vibration should be with respect to the ink droplet spraying cycle accurately regularly.

The device that produces sound wave comprises a piezo-electric crystal that runs through a whole row nozzle, and its effect is that the printing ink main body in the oil ink passage of row nozzle supply printing ink is moved. Apply appropriate frequency at piezo-electric crystal, the voltage of amplitude and phase place. Piezo-electric crystal expands according to the voltage that applies or shrinks, and printing ink is moved. Because movement is dynamic and continuous, will produce pressure wave in printing ink.

Because printing ink is applied complexity and the cost that additional sound wave can increase printer, it is suitable for application scenario that cost is not too noted most. This class purposes comprises the color digital printing of using in short-term, and the high-speed colour office printer of high-quality.

The viscosity operation

The present invention adopts the accurate operation fall low viscous printing technique to depend on many factors, and these factor major parts can both be in the process of making printhead, the making of printing ink or accurately controlled during printer operation. These factors comprise:

1) spout radius

2) nozzle length

3) barrel geometry

4) the ink pressure cycle

5) ink pressure wave amplitude

6) the stable compensation of ink pressure

7) the heater-driven pulsion phase is for the phase place of ink pressure ripple

8) heat pulse energy

9) heat pulse is about the Energy distribution of time

10) heater geometry shape

11) relative position of heater and nozzle

12) thermal conductivity of nozzle material

13) thermal conductivity of printing ink

14) with respect to the ink viscosity of temperature

The computer simulation of nozzle dynamic characteristic

With computer comprehensive simulation has been carried out in the operating process of printhead. Figure 21 to 25 is some results that the nozzle of the embodiment of the invention is simulated, and this routine nozzle adopts when operation and falls low viscous electric heating ink droplet selection mode. In simulation, do not simulate the ink droplet separator. Therefore, selected ink droplet does not separate from the printing ink main body, and returns in the nozzle. In order to make the exercisable printer of throwing in as required, the ink droplet selecting arrangement of simulation must combine with suitable ink droplet separator herein.

The characteristic of the phenomenon of observation is extremely useful to determining to be difficult to directly in computer simulation. Owing to following several reasons, the operation of nozzle is difficult to observe by experiment, and these reasons comprise:

1) nozzle of the present invention's use is miniature, and the feature of important phenomenon is in 1 μ m magnitude.

The time scale of 2) spraying ink droplet only has several microseconds, needs high observation speed.

3) important phenomenon occurs in opaque inside of solid material, can not directly observe.

4) some important parameters heat flow for example, viscosity and fluid velocity are difficult to direct observation.

5) expense of manufacturing experiment nozzle is very high.

Computer simulation has overcome above-mentioned problem. The software kit that is used for a kind of advanced person of fluid dynamic simulation is Fluid Dynamics Intemational Inc.ofIllinois, USA FDI) FIDAP that makes. FIDAP is the registration mark of FDI. On market, also can obtain other simulation softwards, but why select FIDAP to be because it at the fluid dynamic simulation of transition, energy shifts, and the aspect such as surface tension calculating has very high precision. The FIDAP version that adopts is FIDAP7.06.

The theoretical foundation of calculating

In the FIDAP 7.0 Thoery Manual (in April, 1993) that FDI publishes, describe the theoretical foundation that adopts Finite Element Mothod to carry out hydrodynamic analysis and power conversion calculating in detail, and the method for in the FIDAP computer program, using this theoretical foundation, foregoing can be used as reference of the present invention.

Material behavior

The table that is used for the material behavior ＂ of FIDAP simulation at ＂ has provided the approximate physical characteristic of material, and these materials can be used to make printhead.

The character of the ＂ printing ink ＂ that uses in this simulation is the hot melt black ink that comprises the solid pigment of dispersion for a kind of in carrier, and carrier is by C₁₈-C ₂₄The mixture of acid or alcohol and/or the molten o'clock suitable wax between 60 ℃ to 80 ℃ consists of. Under the environment temperature of simulation (80 ℃), carrier is liquid, and viscosity approximately is 100cP. The viscosity number of hot melt printing ink does not represent any specific composition, and is a kind of target viscosities curve of suggestion. Black colorant is 2% Acheson graphite, and granularity is less than 10 μ m. Graphite provides a kind of and has had good stability and non-fading dense black colorant, and can increase the thermal conductivity of printing ink. Acheson graphite has 150Wm in the direction that is parallel to the axis that stretches in the time of 100 ℃^-1k ^-1Thermal conductivity, have 111Wm in the direction perpendicular to the axis that stretches^-1k ^-1Thermal conductivity. Increased the thermal conductivity of ink carrier as colouring agent with graphite. Very important on one point, because high speed and the relatively high thermal conductivity of lower powered action need. If select not possess the colouring agent of high-termal conductivity, and the thermal conductivity of ink carrier is lower, just should be increased at least 0.5Wm to thermal conductivity with other modes for high-speed printer^-1k ^-1。

For with the transient state Free-surface model of FIDAP7.06 according to the time acquisition convergence of micron-sized surface tension variations and Microsecond grade, need to adopt nondimensional simulation.

The table that is used for the material behavior ＂ of FIDAP simulation at ＂ has provided the numerical value that uses in the simulation of adopting the FIDAP program. Most of numerical value are taken from CRC Handbook of Chemistry and Physics, 72nd edition, or the handbook of chemistry of Lange, 14thedition.

＜be used for the material behavior of FIDAP simulation 〉

Characteristic		Physical quantity (SI unit)	Dimensionless numerical value
				Characteristic length (L)	All	1μm	1
Characteristic velocity (U)	Printing ink	1ms	-1					1
				Characteristic time	All	1μs	1

Static temperature	All	80℃	80
				Viscosity (η)	At 80 ℃	100cP	153
	At 100 ℃	10cP	15.3
					At 120 ℃	2cP	3.06
	At 140 ℃	1.5cP	2.29
					At 160 ℃	1.2cP	1.84
	At 180 ℃	1.0cP	1.53
				Surface tension (γ)	At 20 ℃	27mNm -1	41.3
	At 80 ℃	22mNm -1	33.7
					At 160 ℃	18mNm -1	27.6
The pressures cycle cycle	Printing ink	72μs						72
				The driving pulse duration	Heater	36μs	36
Thermal conductivity (k)	Printing ink (2% graphite)	2.6Wm -1k -1	4.12
					Silicon metal	148Wm -1k -1	234.5
	Amorphous SiO2	1.5Wm -1k -1	2.377
					Heater	23Wm -1k -1	36.45
	Si 3N 4	19Wm -1k -1	30.11
				Concrete heat (cp)	Printing ink	2,000Jkg -1k -1	2.071
	Silicon metal	711Jkg -1k -1	0.7362
					Amorphous SiO2	738Jkg -1k -1	0.7642
	Heater	250Jkg -1k -1	0.2589
					Si 3N 4	712Jkg -1k -1	0.7373
Density (p)	Printing ink	0.9gcm -3	1.38
					Silicon metal	2.32gcm -3	3.551
	Amorphous SiO2	2.19gcm -3	3.352
					Heater	10.5gcm -3	16.07
	Si 3N 4	3.16gcm -3	4.836

The hydrodynamic analogy result

Figure 20 to 25 has represented thermodynamics and the hydrodynamic analogy curve of the combination of a routine nozzle. Because this routine nozzle is columnar, adopts axisymmetric analog form. The shape of cylinder can produce five kinds of deviations. Here it is and being connected of heater, since the laminar airflow that the movement of paper causes, gravity (if printhead is not vertical), and the geometry of nozzle cylindrical shell is counted greater than 25 μ m from symmetry axis, and the adjacent nozzle that exists on the substrate. These factors are very little on the impact that ink droplet sprays.

Figure 22 is the function of time curve of ink pressure. Pressure changed according to sinusoidal rule with the cycle of 72 μ s. Represented in the drawings the Three pressures circulation. The unit of transverse axis is 100 μ s, from 0 μ s to 216 μ s.

Figure 21 represents in the nozzle function of time of temperature on each aspect, and the electrical heating pulse is to provide in the 3rd circulation of Figure 20. Pulse originates in 160 μ s, and the duration is 36 μ s. The top of pulse is shaped, so as impulse duration the temperature stabilization of nozzle tip (the printing ink meniscus is contact nozzle from here) maintain about 180 ℃, shown in curve B. Curve A represents the temperature of heater center. Curve C represents on the print head surface temperature on a bit apart from heater 14.5 μ m places. Identical among transverse axis and Figure 20. The unit of the longitudinal axis is 100 ℃. Environment temperature is 80 ℃.

Figure 22 represents the function of time of meniscus extreme position. Identical among transverse axis and Figure 20. The first two circulation (0 μ s is to 144 μ s) represents unselected ink droplet, is not activated heater this moment. In this case, temperature is very low, and viscosity very high (100cP). High viscosity makes printing ink seldom mobile under the pressure variation effect of Figure 20 (peak value approximately changes 2 μ m to peak value). The 3rd cycle period at pressure wave starts heater, and temperature is increased as shown in figure 21. Since reduced viscosity, the nearly 10 μ m of the movement of meniscus. Difference between non-selected ink droplet and the selected ink droplet on meniscus position makes the ink droplet separator can guarantee to allow selected ink droplet transfer to recording medium and forms a point, and unselected ink droplet then can not be transferred on the recording medium. Do not represent the ink droplet separator in simulation, therefore, selected ink droplet is got back in the nozzle. 196 μ s can see this phenomenon in the cycle of 216 μ s from Figure 22.

Figure 23,24,25,27 and 28 expression nozzle cross sections during operation. The tip region that has only represented nozzle is because select relevant most of phenomenons all to appear at this zone with ink droplet. These curves have represented from the nozzle tip cross section of the outside 22 μ m distances of symmetry axis. Spout radius is 10 μ m, and curve adopts corresponding scale. In these figure, the 100th, printing ink, the 101st, silicon chip, the 102nd, SiO₂, the position of 103 expression ring heaters, one side, the 108th, Si₃N ₄Passivation layer, the 109th, hydrophobic face coat.

Figure 23 (a), 23 (c), 23 (e) 23 (i) according to 5 ℃ time interval hot isopleth. Figure 23 (b), 23 (d), 23 (f), 23 (h) and 23 (j) are illustrated in the viscosity isopleth on each time point and ink droplet differentiation situation in the ink droplet spraying cycle.

Figure 23 (a) is illustrated in the times 160 μ s place shown in Figure 20 to 22, i.e. temperature isopleth when heater-driven pulse begins. The power that offers at this moment heater is 180mW. Environment temperature is 80 ℃, and from 85 ℃ to 120 ℃ by 5 ℃ time interval the temperature isopleth.

Viscosity isopleth during Figure 23 (b) expression 160 μ s. The viscosity of monoblock printing ink is 100cP, and the viscosity of this moment changes very little. Solid material (silicon chip 101, SiO2102, and Si₃N 4108) in line represent that limited element calculates mesh.

Figure 23 (c) expression times 170 μ s place, i.e. temperature isopleth after heater-driven pulse begins during 10 μ s. The power that offers at this moment heater is 74mW. From 85 ℃ to 195 ℃ by 5 ℃ time interval the temperature isopleth.

Viscosity isopleth during Figure 23 (d) expression 170 μ s. Ink viscosity changes near below the 2cP at heater place from the 100cP away from heater.

Figure 23 (e) expression times 180 μ s place, i.e. temperature isopleth after heater-driven pulse begins during 20 μ s. The power that offers at this moment heater is 60mW.

Viscosity isopleth during Figure 23 (f) expression 180 μ s. Moving range when the ink pressure that the ink viscosity that reduces has allowed to increase makes printing ink more not driven than heater is larger. Viscosity on the nozzle tip end wall is minimum, and the temperature here is the highest. Help like this movement of printing ink, because ink viscosity is larger than nozzle-axis place near nozzle wall section to the retardation that printing ink moves.

Figure 23 (g) expression times 190 μ s place, i.e. temperature isopleth after heater-driven pulse begins during 30 μ s. The power that offers at this moment heater is 58mW.

Viscosity isopleth during Figure 23 (h) expression 190 μ s. The ripple of viscosity isopleth (particularly from the 4cP isopleth as seen) is the result of calculation of finite element simulation, and it is by the interpolation method in the element and in conjunction with the non-linear relation acquisition of temperature and viscosity. Interpolation method has been left in the basket on the impact of simulation.

Figure 23 (i) expression times 200 μ s place, i.e. temperature isopleth after heater-driven pulse begins during 40 μ s. This is the moment of 4 μ s after heater turn-offs, and the maximum temperature in this stage is 155 ℃.

Viscosity isopleth during Figure 23 (j) expression 200 μ s. At this one-phase, the ink droplet separator has become the principal element of definite meniscus position. Most of high temperature, low viscous printing ink have formed selected ink droplet gradually, and form a point in recording medium. On the viscosity of the selected ink droplet of reduction and the fiber that the rising temperature helps to make ink droplet be bonded at fibrous recording medium before ink droplet solidifies.

Figure 24 represents the meniscus position situation of movement of unselected ink droplet a cycle period. In the drawings from 88 μ s to 128 μ s according to the time interval of 10 μ s the printing ink meniscus position. These positions are corresponding with the same phase of the ink pressure ripple from 160 μ s to 200 μ s shown in Figure 25. Meniscus is along with about 2 μ s are moved in the vibration of pressure.

Figure 25 represents the situation that ink droplet selection cycle period meniscus position moves. In the drawings by 10 μ s time interval the printing ink meniscus position from 160 μ s to 200 μ s. These positions are corresponding with the same phase of the ink pressure ripple from 88 μ s to 128 μ s shown in Figure 24. Because the reduced viscosity of heated ink, meniscus is along with about 10 μ m are moved in the vibration of pressure.

Figure 26 represents the function of time of the meniscus extreme position of simulating, and therein the ink pressure wave frequency is selected with ink droplet and the frequency of separating has all reduced half. The maximum printable speed of this structure is half of the sort of structure of analog result shown in Figure 20 to 25. Yet the position absolute difference between non-selected ink droplet and the selected ink droplet has been increased, thereby has increased the opereating specification of ink droplet separating step. Transverse axis is identical with Figure 20, but time shaft is pressed coefficient 2 expansions. The longitudinal axis scale of curve is different from Figure 20. The first two circulation (0 μ s is to 288 μ s) represents unselected ink droplet, is not activated heater this moment. In this case, temperature is very low, and viscosity very high (100cP). High viscosity causes and move among a small circle (peak-to-peak value is approximately 4 μ m) under the pressure variation effect in 144 μ s cycles. In the 3rd circulation of pressure wave, start heater. The reduction of viscosity is so that meniscus moves about 15 μ m. Do not simulate the ink droplet separator in simulation process, therefore, selected ink droplet can be got back in the nozzle. This point can be seen during the cycle of 432 μ s by 392 μ s from Figure 26.

Figure 27 is illustrated in when not selecting ink drop the meniscus shift position in the circulation. In the drawings by 20 μ s time interval the printing ink meniscus position from 176 μ s to 256 μ s. These positions are corresponding with the same phase of the ink pressure ripple from 320 μ s to 400 μ s shown in Figure 28. Meniscus is along with about 4 μ m are moved in the vibration of pressure.

Figure 28 represents the movement of meniscus position in ink droplet is selected to circulate. In the drawings by 20 μ s time interval the printing ink meniscus position from 320 μ s to 400 μ s. These positions are corresponding with the same phase of the ink pressure ripple from 176 μ s to 256 μ s shown in Figure 27. Because the reduced viscosity of heated ink, meniscus is along with about 16 μ m are moved in the vibration of pressure.

The nozzle arrangements that produces these analog results shown in Figure 28 to 28 is different from the nozzle arrangements shown in Fig. 1 and 2. The nozzle of printhead can have multiple possible structure. Because the requirement of the basic demand specific heat inkjet nozzle of nozzle what want simple, for the facility of manufacture craft, the actual geometric configuration of nozzle has larger choice.

Variable ink droplet model

Can adopt several means in order to change the ink droplet model, in order to double-deck time printer is made into the mode of operation of continuous tone (contone) printer. The excursion of ink droplet model depends on printhead, drive circuit, ink droplet separator, and the precise characteristics of used printing ink.

Connecing one mode according to one modulates the device of ink droplet model and comprises:

1) time in modulation heater pulse forward position, keeps rear along constant.

2) time on edge after the modulation heater pulse, keep the forward position constant.

3) time in modulation heater pulse forward position, keep pulse width constant.

4) voltage of modulation heater pulse.

Above overall and preferred embodiment of the present invention described. The feature of a specific embodiment has been described in the table of appendix A. Those skilled in the art obviously can make various changes to overall and specific embodiment under the condition that does not break away from the scope of the invention. Appendix A

This is a kind of four-color printhead for A4 number printing for A4-4-600 type monolithic LIFT printhead. Printhead is fixed, and is the full pagewidth of A4 paper. The resolution ratio that is used for recording quality output is double-deck time of 600dpi.
	The keystone specification foundation
Resolution ratio ... 600dpi technical specification printhead length ... the 215mm print area width adds 5mm printhead width ... 5mm is according to physics and the level restriction ink colors of printhead ... 4 CMYK page sizes ... A4 illustrates print area width ... the every row pixel of 210mm/resolution printing zone length ... total length one page time-write interval that 297mm prints ... 1.3 second according to fluid dynamic properties, nozzle quantity etc. page per minute ... 45ppm is used for every stature recording medium speed of full page face size ... 22.0cm/sec L/ (resolution ratio*The drive cycle time number of phases) basic I C technique ... 1.5 μ mCMOS suggestion bit diagram memory requirement ... 16.6MBytes the memory pixel interval that when not using compression, needs ... 42.33 reciprocal every row number of picture elements of μ m resolution ratio ... 4, every page of line number of 960 effective nozzle/number of colors ... 7,015 scanning distances*Every page of number of picture elements of resolution ratio ... 34,794,400 every row number of picture elements*Every page of ink droplet number of every page of line number ... 139,177,600 every page of number of picture elements*The ink colors mean data rate that uses simultaneously ... 12.3MByte/sec per second number of picture elements*Glossy black color/8 Mbits
	Yield rate and cost foundation
The chip-count of every stature ... 1 suggestion wafer size ... the chip on each wafer of integral product is adopted in the 300mm suggestion ... the 36 wafer size print head chip areas according to chip size and suggestion ... 10.7cm2The chip width*Length is without fault-tolerant sorting yield rate ... 0.87% adopts the method for Murphy, defect concentration=1/cm2Fault-tolerant sorting yield rate is arranged ... 0.90% calculating (the D=1/cm referring to fault-tolerant yield rate2CF=2) fault-tolerant total yield rate is arranged ... the 0.90% qualified printhead of making per month according to 80% reliable making yield rate ... 260,208 hypothesis are per month from 10,000 wafer begins the printhead assembly cost ... the miscellaneous payment of $ 10 each printhead of estimation ... $ 13 equips required cost 120 m of 1.5 μ m production lines after according to depreciation in 5 years again, add the wafer cost of each printhead of P.A. running cost of $ 16m ... $ 23 is according to the printhead assembly basis of material cost $ 600 estimations of each wafer ... $ 46 printheads assemblings, the summation of miscellaneous and wafer cost

Appendix A (continuing)

A4-4-600 type monolithic LIFT printhead
	Nozzle and type of drive foundation
Spout radius ... 14 μ m specifications drive the number of phases ... the every phase nozzle of 8 specifications ... 2,480 according to pagewidth, effective nozzle number of resolution ratio and the every stature of color ... 19,840 drive the number of phases*The redundant nozzle of the every stature of every phase nozzle number ... 19,840 100% when redundant with total nozzle number of effective identical every stature of nozzle number ... 39,680 effective nozzles add the input speed of redundant each nozzle of nozzle ... 5,208Hz 1/ (the heater-driven cycle*The number of phases) heater radius ... 14.5 μ m is according to nozzle geometry and radius heater film resistance ... 2.3 μ Ω m for the heater heater resistance 2,095 made from TaA1 according to heater size and the average heater pulse electric current of resistance ... 5.6mA according to heater power and resistance heater drive cycle ... 24 μ s are according to the landing time between the finite element analog pulse ... 168 μ s drive cycles*(driving the number of phases-1) every row clock pulse ... 2,834 are provided with a plurality of clocks and do not have the shift register clock frequency ... 14.8Mhz clock pulses and per second line number driving transistors conducting resistance according to every row ... the 42 device geometries average print head driving voltages according to suggestion ... 12.0V hot device electric current*(heater+driving transistors resistance) ink droplet is selected temperature ... the m. p. heater peak temperature of 75 ℃ of surfactant colloidal sol or PIT microemulsion ... 120 simulate according to finite element

The ink characteristics foundation

Basic ink carrier ... water specification surfactant ... Arachidic acid obtains the suggesting method droplet volume of temperature threshold ... 18pl simulates printing ink concentration according to finite element ... 1.030g/cm3Black ink concentration ink drop quality in the time of 60 ℃ ... 18.5ng ink drop volume*Printing ink concentration printing ink specific heat capacity ... 4.2J/Kg/ ℃ self cooled ceiling capacity of ink carrier characteristic ... 2,715nJ/ drips ink droplet thermal capacity*The injection energy that temperature rise is every ... 1,587nJ offers the energy of the energy printing all black page of heater in the finite element simulation ... the 221J ink droplet sprays energy*The total ink of every page of upper every kind of color of every page of ink droplet number ... 0.63ml every page of upper every kind of color ink droplet number*The maximum printing ink flow velocity of every kind of color of droplet volume ... 0.47ml/sec every page of upper every kind of color ink amount/one page time-write interval all black printing ink covers ... 40.2ml/m2Droplet volume*Number of colours*Every square metre of ink droplet is counted the ink jet surface tension ... 38.5mN/m spray the surface tension ink pressure that needs ... 5.5KPa 2*Ink jet surface tension/spout radius printing ink post height ... 545mm obtains the printing ink post height of ink pressure

Claims (29)

1. a Method of printing of throwing in as required may further comprise the steps:

(1) with the power of following coincidence to the printing ink addressing in the selected nozzle of printhead:

(a) be higher than the power of external pipe pressure, and

(b) select energy pulse for one, the synthetic effect of these doubling forces is enough to make chosen printing ink part to be out-diffusion to preset range from corresponding nozzle, surpass the printing ink in the non-selected nozzle, but the printing ink overall separation that can't be connected with them; And

(2) in this address step, attract printing ink from printhead towards print area with powerful and approaching power, thereby:

(a) make selected ink diffusion to above-mentioned scope, the printing ink overall separation that is connected with them, and

(b) non-selected printing ink is separated.

2. according to the method for claim 1, it is characterized in that the step of addressing comprises the printing ink that heats in the selected nozzle.

3. according to the method for claim 2, it is characterized in that ink composition and heat energy have such relation: namely select by the poor ink droplet of realizing of the surface tension between the printing ink in chosen and the non-selected nozzle.

4. according to the method for claim 2, it is characterized in that ink composition and heat energy have such relation: namely realize the ink droplet selection by the differences in viscosity between the printing ink in chosen and the non-selected nozzle.

5. according to the method for claim 1, it is characterized in that above-mentioned attraction step adopts an electric field, and above-mentioned printing ink conducts electricity.

6. according to the method for claim 1, it is characterized in that above-mentioned attraction step adopts a magnetic field, and above-mentioned printing ink can be subject to magnetic field suction.

7. throw in as required print system and comprise a kind of printing ink that can be subject to magnetic field or electric field attracts for one kind, printer with nozzle, and make printing ink in the nozzle be subject to being higher than at least the device of the pressure of ambient atmosphere pressure 2%, or according to endless form change pressure, above-mentioned printhead also comprises an electric control gear that is used for selecting ink droplet, this device reduces surface tension or the viscosity of above-mentioned printing ink, make the meniscus of above-mentioned selected ink droplet under above-mentioned pressure-acting, be enough to flow to the position different from the meniscus of non-selected ink droplet, and the ink droplet separator, be used for the selected ink droplet of attraction from printer towards recording medium.

8. according to the system of claim 7, it is characterized in that the capillary device of above-mentioned reduction comprises provides device from heat to selected nozzle tip.

9. according to the system of claim 8, it is characterized in that above-mentioned to provide the device of heat to selected nozzle tip be an electric heating driver.

10. according to the system of claim 7, it is characterized in that above-mentioned low viscous device comprises provides the device from heat to selected nozzle that falls.

11. according to the system of claim 10, it is characterized in that above-mentioned to provide the device of heat to selected nozzle tip be an electric heating driver.

12. according to the system of claim 7, it is characterized in that the ink droplet separator is the electric field that acts on the electrically conductive ink.

13. according to the system of claim 7, it is characterized in that the ink droplet separator is the magnetic field that acts on the liquid ink that contains magnetic particle.

14. according to the system of claim 7, it is characterized in that recording medium is paper.

15. according to the system of claim 7, it is characterized in that recording medium is transparent film.

16. according to the system of claim 7, it is characterized in that recording medium is fabric.

17. the method according to claim 1 is characterized in that, in heating during printing ink, selects the energy required with separating ink drop required energy less than not the separating printing ink and be heated to ink droplet selection temperature of equal volume the time.

18. according to the system of claim 7, it is characterized in that above-mentioned printing ink and electric control gear are to consist of like this, so that select the energy required with separating ink droplet required energy less than not the separating printing ink and be heated to the ink droplet separation temperature of equal volume the time.

19. liquid ink printhead that heat drives, it is characterized in that, it is little to spray the required energy comparison of ink drop, and it is lower than the printing ink of above-mentioned ink droplet equal volume is elevated to the required energy of uniform temperature that is lower than the ink droplet injection temperation from the temperature that is higher than the environment ink temperature.

20. according to the as required input print system of claim 7, it is characterized in that above-mentioned ink droplet selecting arrangement reduces near the ink viscosity of selecteed ink droplet.

21. according to the as required input print system of claim 20, the reduction that it is characterized in that ink viscosity is to cause by near the selected ink droplet temperature is raise.

22. according to the as required input print system of claim 21, it is characterized in that utilizing the electrothermal driving device that near the temperature of selected ink droplet is raise.

23. the as required input print system according to claim 22, it is characterized in that the meniscus position of above-mentioned selected ink droplet is poor is produced by above-mentioned ink droplet selecting arrangement, and the poor deficiency of above-mentioned meniscus position of above-mentioned selected ink droplet so that selected ink droplet separate from above-mentioned printing ink main body.

24. according to the as required input printing equipment of claim 20, it is characterized in that the above-mentioned device of printing ink pressurized that makes is fit to apply the pressure that changes by endless form.

25. according to the as required input print system of claim 20, it is characterized in that used printing ink at room temperature is solid, but under the operating temperature of printhead, be liquid.

26. according to the as required input print system of claim 24, it is characterized in that the above-mentioned variation of ink pressure is produced by a piezoelectric device, apply the voltage of variation at piezoelectric device.

27. according to the as required input print system of claim 26, it is characterized in that above-mentioned ink pressure is according to drop ejection frequency or the fluctuation of its integral multiple.

28. according to the as required input print system of claim 20, it is characterized in that recording medium is a kind of plastic film.

29. according to the as required input print system of claim 20, it is characterized in that the ink droplet separator makes recording medium proximity printing head.

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