EP0052914B1 - Printer head for an ink-on-demand type ink-jet printer - Google Patents

Printer head for an ink-on-demand type ink-jet printer Download PDF

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Publication number
EP0052914B1
EP0052914B1 EP19810302728 EP81302728A EP0052914B1 EP 0052914 B1 EP0052914 B1 EP 0052914B1 EP 19810302728 EP19810302728 EP 19810302728 EP 81302728 A EP81302728 A EP 81302728A EP 0052914 B1 EP0052914 B1 EP 0052914B1
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EP
European Patent Office
Prior art keywords
ink
pressure
valve
pressure chamber
control means
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Expired
Application number
EP19810302728
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German (de)
English (en)
French (fr)
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EP0052914A1 (en
Inventor
Michihisa Suga
Mitsuo Tsuzuki
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NEC Corp
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NEC Corp
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Publication of EP0052914A1 publication Critical patent/EP0052914A1/en
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
    • B41J2/01—Ink jet
    • B41J2/17—Ink jet characterised by ink handling
    • B41J2/175—Ink supply systems ; Circuit parts therefor
    • B41J2/17596—Ink pumps, ink valves

Definitions

  • This invention relates to a printer head for an ink-on-demand type ink-jet printer in which ink droplets are squirted out each time a driving pulse is applied to an electromechanical transducer attached to one wall of an ink chamber.
  • This previously proposed printer head has a nozzle through which ink droplets are to be squirted, a supply passage for supplying ink from an ink tank, pressure exertion means for exerting pressure on the ink in accordance with an electric signal to squirt the ink droplets and fluid control means including two non-deformable valves which are disposed in the ink passage and can be solenoid operated.
  • the present invention is characterised by the features set out in claim 1.
  • a nozzle 104 and an ink feed port 105 communicate with a pressure chamber 103 which is filled with ink and which genertes a pressure pulse by deforming a wall 102 with electromechanical transducer means 101.
  • the ink feed port 105 feeds the ink from an ink tank to the pressure chamber 103.
  • a piezoelectric element is mainly employed as the electromechanical transducer means 101. The piezoelectric element is fastened to the wall 102.
  • ink droplet is carried out as follows.
  • the wall 102 is curved inwardly of the pressure chamber 103 by applying the voltage to the piezoelectric element 101, the internal volume of the pressure chamber decreases, and ink within the pressure chamber is forced out of the pressure chamber.
  • the ink pressure at this time squirts the ink from the nozzle 104.
  • the ink pressure from the pressure chamber acts also on the ink feed port 105, and also an ink stream which returns from the ink feed port to the ink tank arises.
  • the ink feed from the ink tank is continued at the ink feed port 105.
  • the supply for the ink previously squirted from the nozzle 104 finishes off.
  • the droplet forming operation in the conventional ink-on-demand type ink-jet printer has involved several problems as stated hereunder.
  • the ink pressure generated by the deformation of the wall of the pressure chamber acts, not only on the nozzle portion, but also on the ink feed port, so that the loss of energy dissipated otherwise than the droplet formation is great.
  • the volume change of the pressure chamber needs to be made large by applying high electric energy to the piezoelectric element. This has led to such problem as degradation in the characteristics of the piezoelectric element and lowering in the response rate of the droplet formation.
  • the number of ink droplets to be formed within one second or the ink droplet frequency is at most 3KHz or so in a practical range, and the highest frequency with the fluctuations of the characteristics neglected is approximately 10KHz.
  • the prior art has therefore been unsuitable for high-speed high-density printing.
  • An ink-jet printer head in which an ink passage on the ink feed side is constructed of a fluidic element in order to enhance the energy efficiency at the droplet formation is disclosed in the United States Patent No. 3,848,118.
  • the fluidic element has the effect that the flow resistance to an ink stream changes depending upon the direction of the ink stream, and it intend to enhance the energy efficiency at the droplet formation. Since, however, the fluidic element attains kind of rectification characteristic by utilizing physical properties inherent in fluids, there are such problems that the characteristic fluctuates depending upon the nature of the fluid used and that the ratio of the flow resistance changes responsive to the directions of the ink stream cannot he set large. Moreover, the fluidic element has been structurally complicated and has been attended with much difficulty in disposing it within the ink-jet printer heads.
  • An object of this invention is to provide a novel ink-jet printer head which solves the various problems in the prior art.
  • a printer head for an ink-on-demand type ink-jet printer for squirting ink droplets onto a printing medium
  • said printer head comprising: a nozzle for squirting said ink droplets; a supply passage for supplying ink in communication with an ink tank; pressure exertion means for exerting a pressure on said ink in accordance with an electric signal to squirt said ink droplets; and fluid control means having a valve which is deformed under the action of the ink pressure.
  • the first embodiment of this invention includes an ink-jet printer head 10 which is constructed of a nozzle 14 for squirting ink, a supply passage 15 communicating with an ink tank (not shown) and for supplying the ink, a pressure chamber 13 filled with the ink, a piezoelectric element 11 fastened to a wall 12 of the pressure chamber, first fluid control means 21 disposed between the nozzle 14 and the pressure chamber 13, and second fluid control means 22 disposed between the pressure chamber 13 and the supply passage 15.
  • first fluid control means 21 disposed between the nozzle 14 and the pressure chamber 13
  • second fluid control means 22 disposed between the pressure chamber 13 and the supply passage 15.
  • the fluid control means 21 and 22 operates so that the flow resistance may become low under the action of the pressure of the ink in response to the ink stream in the direction of from the supply passage side toward the nozzle side, whereas the f!ow resistance may become high under the action of the ink pressure in response to the ink stream in the direction of from the nozzle side toward the supply passage side.
  • ink droplets in the ink-jet printer head 10 is carried out as follows:
  • the wall 12 is curved inwardly of the pressure chamber 13 by applying a voltage to the piezoelectric element 11 through electrodes 16 and 17 from a power source 18, the pressure owing to the wall 12 acts on the ink within the pressure chamber 13.
  • the stream from the pressure chamber 13 toward the nozzle 14 acts on the first fluid control means 21 so as to render the flow resistance low
  • the stream of the ink from the pressure chamber 13 toward the supply passage 15 acts on the second fluid control means 22 so as to render the flow resistance high.
  • the difference of the two flow resistances becomes large, the ink forced out of the pressure chamber flows out principally toward the nozzle side, and the ink droplet is squirted from the nozzle 14. Subsequently, when the voltage applied to the piezoelectric element 11 is returned to zero or voltage of the opposite polarity is applied so as to render the deformation of the wall 12 of the pressure chamber null or to curve the wall outwardly of the pressure chamber, the interval volume of the pressure chamber 13 increases and the pressure inside the pressure chamber 13 decreases.
  • the stream from the nozzle 14 toward the pressure chamber 13 acts on the first fluid control means 21 to render the flow resistance high
  • the ink stream from the supply passage 15 toward the pressure chamber 13 acts on the second fluid control means 22 to render the flow resistance low.
  • the ink flows principally from the supply passage 15 into the pressure chamber 13, and the extent to which the meniscus in the nozzle portion is retracted into the nozzle lowers.
  • the deformation of the pressure chamber 13 acts for squirting the ink droplet when the volume of the pressure chamber decreases, and it acts for supplying the ink when the volume to the pressure chamber increases. Therefore, the dissipation of energy onto the supply passage side at the ink droplet squirt as in the prior art lessens, and the energy efficiency is enhanced. Further, since the retraction of the meniscus into the nozzle at the ink supply lessens, the period of time required for the meniscus to revert to the nozzle end part is shortened.
  • the ink-jet printing apparatus since the change of the internal volume of the pressure chamber by the piezoelectric element may be small on the same order as the volume of the ink droplet, the period of time for forming the droplet can be shortened in the extreme. Since excess electric energy need not be applied to the piezoelectric element, the degradations of the characteristics of the piezoelectric element are not incurred. Further, in the prior art, the ink supply is relied on the surface tension of the meniscus at the nozzle portion, whereas the ink is supplied from the supply passage owing to the increase of the internal volume of the pressure chamber and forcibly performs the ink supply by the use of the external energy such as electric energy, so that the ink supply for the high-speed droplet formation is possible. Thus, the ink-jet printing apparatus according to this invention has realized the droplet formation at very high speed.
  • the ink flows in the pressure chamber from the nozzle portion and the supply passage.
  • the fluid control means located on the supply passage side operates so that the flow resistance may decrease.
  • the flow resistance in the supply passage can be set so as to become less than that in the nozzle portion. As a result, most of the ink flows from the supply passage into the chamber. In this manner, the ratios between the flow resistances in the nozzle portion and the supply passage in case of the extrusion and retraction of the ink from and into the pressure chamber are made different, whereby the same effect as in the first embodiment can be brought forth.
  • a similar effect is also attained in the case where the fluid control means is disposed between the pressure chamber and the nozzle.
  • the flow resistance of the fluid control means is smaller under a high internal pressure than that under a low internal pressure.
  • the stream of the ink in the on-demand type ink-jet printer head is always pulsatile, and the quantity of the ink which is passed through a valve by one pulsatile stream is as extremely small as approximately equal to at most the volume of the ink droplet.
  • the volume of the space in which the valve moves is made sufficiently smaller than the quantity of the ink to pass through the valve.
  • a flat valve 301 made of an elastic member is arranged so as to cover an ink outflow port 302.
  • the valve 301 is fixed in close contact with a valve seat 304 by means of a stationary portion 303.
  • a movable portion 305 lies in close contact with a valve seat 306.
  • the dimension of the overlap parts 309 of the valve and the valve seat needs to be made small so as to reduce the pressure loss.
  • the material of the valve there can be used thin films of metals such as gold, nickel and stainless steel and various plastic films.
  • the movable portion 305 and the outflow port 302 of the valve are respectively made square with each side being 200 um long and 180 11m long, and the length of the overlap part 309 is set to 10 11m.
  • the valve is formed by punching from the polyethylene terephthalate film of 20 11m thick. The valve is fixed in such manner that the stationary portion 303 is pressed against the valve seat 304 by a fixing member 307.
  • the wall 12 of the pressure chamber 13 is made of a cold-rolled stainless steel plate of 0.4 mm thick.
  • the piezoelectric transducer may be of NEPEC N-10 having dimensions of 2 mmx26 mmxO.4 mm.
  • the piezoelectric transducer is fastened to the wall 12 with an epoxy type solventless thermosetting binder.
  • the droplet formation is carried out by supplying the piezoelectric transducer with a pulse voltage which has a waveform corresponding to one wavelength of the cosine wave.
  • the formation of an ink droplet having a diameter of about 100 pm and an initial velocity of about 2.4 m/sec is observed at a pulse width of 55 psec and a peak voltage of 80 V.
  • the maximum value of the operating frequencies at which the fluctuations of the initial velocity of the droplet fall within 10% is 18 KHz.
  • the operating frequency is about 12 KHz under the operating conditions mentioned above.
  • the operating frequency for fulfilling the droplet velocity fluctuations of within 10% is at most only about 1.5 KHz.
  • the geometries of the valve it is advantageous in the assemblage job to make the geometries of the valve as large as possible. In this case, however, the geometries must be limited to the range in which the volume of the moving space of the valve is smaller than the volume of the droplet.
  • the valve enlarges, also its thickness needs to be increased. For example, when the sides of square valve made of polyethylene terephthalate enlarged to 300 pm and 400 pm, the thicknesses of the valves needed to be made 35 pm and 75 pm, respectively. It has been confirmed that when the dimensions of the valve are further enlarged, the effect of the valve lowers abruptly.
  • the fluid control means in this invention has its one feature in exploiting the displacement of the valve owing to the ink pressure.
  • the displacement of the valve needs to be made within the elastic limit thereof.
  • the valve is displaced beyond the elastic limit, it is deformed and cannot return to its original closed state.
  • a pressure range in which the elastic limit is not exceeded is narrow. Therefore, it has sometimes been the case that an excess ink pressure acts to deform the valve at, for example, the initial charging of the ink-jet printer head with the ink.
  • a doughnut-shaped disc valve 401 made of an elastic member is fixed in close contact with a valve seat 404 by a stationary portion 403, and in the absence of the stream of the ink, also a movable portion 405 lies in close contact with a valve seat 406 so as to blockade an ink outflow port 402.
  • Such valve is constructed of a components as shown in Fig. 4C. More specifically, the valve seats 404 and 406 are unitarily formed in a manner to have the annular outflow port 402 therebetween.
  • the disc valve 401 formed with a hole in its central part is stacked on the valve seats, and a ring-shaped fixing member 407 is further stacked on the valve, to fix the valve.
  • the valve 401 When a pressure causing the ink to flow upwardly acts on the valve, the valve 401 is pushed up similarly to the cantilever valve in Fig. 3, the ink flows out through the opening 408 between the valve and the valve seats as shown in Fig. 4B.
  • the deformation of the disc valve around the central hole thereof as in Fig. 4B includes an elongation in the circumferential direction of the central hole in addition to the same simple bending in the radial direction as in the cantilever valve of Fig. 3. Accordingly, the disc valve is more difficult of deformation than the cantilever valve and has its durability sharply enhanced against the action of intense pressure.
  • the doughnut-shaped disc valve 401 is formed by punching from the polyethylene terephthalate film 20 11m thick.
  • the diameter of the central hole is set at 300 um, and the outside diameter of the movable portion 405 of the valve 401 is set at 500 ⁇ m.
  • the outside diameter of the valve seat 406 is set at 320 ⁇ m so that the length of the overlap parts 409 of the movable portion 405 and the valve seat 406 may become 10 ⁇ m.
  • the fluid control means thus constructed is applied to the ink-jet printer head 10 shown in Fig. 2. As a result, the same effects as in the fluid control means shown in Fig. 3 has been confirmed.
  • various microscopic machining techniques have been known. For example, according to the machining technique called "electroforming", an electrode in the flat shape of the disc valve is plated with gold up to a predetermined thickness in the vertical direction, whereby the disc valve of the gold foil can be formed.
  • the thickness of the valve must be made smaller as the elastic modulus of the material used is greater.
  • the pressure for the droplet formation needs to be made approximately double that in the case of the gold foil.
  • the thickness of the stainless steel valve needs to be made smaller than 5 um.
  • the thin valve however, has such problems that the handling is difficult and that thin foils are difficult to obtain in case of some materials.
  • a valve 501 arranged in close contact with a valve seat 506 so as to cover an outflow port 502 is supported by fine supporting arms 510, and is fixed to the valve seat 506 by a stationary portion 503.
  • the third example can be constructed by successively stacking the valve seat 506 having the outflow port 502 in its central part, a valve member 511 which is centrally located and in which the valve 501 to cover the outflow port is unitary with the peripheral stationary ring 503 through the fine supporting arm 510, and a fixing member 507.
  • the valve 501 is pushed up as shown in Fig.
  • the operation of the valve involves the flexures and elongation of the supporters 510, and the valve has its durability sharply enhanced against the action of intense pressure in comparison with the cantilever valve of Fig. 3.
  • the quantity of the displacement of the valve can be set larger than in the disc valve of Fig. 4, resulting in the advantage that the versatility of the selection of the valve material and the versatility of the design are sharply enhanced.
  • a disc valve 601 in the fourth example of the fluid control means, is fixed in close contact with a valve seat 604 by a stationary portion 603, and in the absence of the stream of the ink, a movable portion 605 lies in a position separate from a valve seat 606 and the parts of the ink before and behind the valve communicate.
  • a pressure acts to cause the ink to flow downwardly, as shown in Fig. 6B, the valve 601 flexes and comes into contact with the valve seat 606, and it acts to prevent the stream of the ink.
  • valve 601 Under the action of a pressure causing the ink to flow upwardly as shown in Fig. 6C, the valve 601 flexes upwards and the ink flows out upwards through the opening 608 between the valve and the valve seat. In this manner, to the end of attaining the rectification effect of permitting the ink to flow in one direction, it is not always necessary that the valve and the valve seat lie in close contact at a standstill.
  • the quantity of flexure of the valve under the ordinary droplet-forming conditions is readily calculated within the scope of the fundamental knowledge of the material strength and is found to be approximately 3 ⁇ m.
  • a stationary rectification effect is accordingly achieved when the spacing between the valve and the valve seat at the standstill is up to 3 11m or so. Needless to say, the fact that the valve and the valve seat need not always lie in close contact at the standstill is applicable, not only to the cases of employing the doughnut-shaped disc valves, but also to the fluid control means shown in Figs. 3 and 5.
  • the spacing between the valve and the valve seat at the standstill is increased beyond the quantity of flexure of the valve, the ink comes to flow also in the opposite direction, and the rectification effect weakens gradually.
  • the flow resistance can be greatly changed depending upon the direction of the ink stream, and hence, a satisfactory function can be exercised as the fluid control means.
  • the flow resistance an inertial resistance and a viscous resistance which are based on the ink stream, and a loss term in the part in which the sectional shape of the flow passage changes.
  • the viscous resistance becomes the greatest with respect to the steady flow after the valve has flexed a fixed amount.
  • the viscous resistance is proportional to d- 3 with respect to the spacing d between the valve and the valve seat. Accordingly, in case where, for example, the spacing between the valve and the valve seat at the standstill is set at 8 um for a valve flexure quantity of 3 pm, the flow resistance changes about 10 times in dependence on the direction of the ink, and a satisfactory function can be achieved as the fluid control means.
  • the above-mentioned structures in which the valve and the valve seat are separated at the standstill have an important advantage from the viewpoint of practical use.
  • the ink meniscus is formed at the end face of the nozzle of the ink-jet printer head, and a liquid component in the ink in the nozzle portion is continually vaporizing.
  • the fluid control means is disposed between the pressure chamber and the supply passage and where the ink passages before and behind the fluid control means are separated from each other by the valve, the ink in the nozzle decreases and the meniscus is retracted into the nozzle.
  • the air is introduced into the pressure chamber and a stable droplet formation can no longer be executed.
  • the ink passage parts before and behind the fluid control means are communicating even at the standstill, the ink is supplied from the supply passage side to the extent that the ink in the nozzle portion has decreased due to the vaporization of the liquid component, and hence, the ink meniscus is always kept at the nozzle end face.
  • the fifth example of the fluid control means shown in Figs. 7A and 7B is constructed of a wall member 35 defining a flow passage of the ink, a plate member 31 provided with an aperture, a spacer 32, a film 33 which can be deformed by the pressure of the ink, and a frame member 34 which has a frame for securing the film and whose outer side is a penetration portion.
  • the bore of the plate member 31 is made smaller than the diameter of the film.
  • the film 33 may be made of sheets of metals such as gold and stainless steel, films of plastics, etc.
  • the ink flows from the passage 36 to the passage 40 through the aperture 37, the opening 38 between the plate member 31 and the film 33, and the penetration portion 39 of the frame member 34. When the ink flows from the passage 40 to the passage 36, it passes in the reverse order.
  • the film 33 curves upwards conversely to the foregoing, the gap width of the opening 38 decreases and the flow resistance increases. For this reason, the overall flow resistance of the flow passage increases.
  • the flow passage whose flow resistance changes depending upon the direction of the ink stream can be provided, and a high-speed ink-jet printer head may be provided by employing it as the fluid control means.
  • the magnitude of the ratio between the flow rates dependent upon the direction of the stream becomes under an identical pressure.
  • the material of the film is polyethylene terephthalate of 10 um thick
  • the diameter of the film is 400 pm
  • the gap width of the opening 38 is 10 pm.
  • the fluid control means is arranged between the ink feed port and the pressure chamber in the conventional ink-jet printer head shown in Fig. 1.
  • a passage 42 having a fixed gap width is disposed between an ink feed port 41 and a pressure chamber 103, the wall of the passage on one side is provided with a hole communicating with the pressure chamber, and a film 43 is fastened to a part of the passage 42.
  • the film the sheet of a metal, plastic or the like can be employed as mentioned above.
  • the quantity of the retracted ink is smaller than the quantity of the squirted ink in the nozzle portion, the period of time in which the retracted meniscus return to the nozzle end is shortened, and it is permitted to shorten the period of the ink droplet formation.
  • the change of the flow resistance is the sum of the fixed value independent of the direction of the ink stream and a value varying under the action of the valve. Accordingly, the flow resistance can also be changed in dependence on the direction of the ink stream in such a way that an auxiliary ink passage having a fixed flow resistance is disposed jointly with the fluid control means which has previously been illustrated in Figs. 3, 4 and 5 and which has the complete rectification action.
  • Fig. 9 shows another example of the fluid control means in which auxiliary ink passages penetrating at all times are respectively provided in the valve seats in the three kinds of fluid control means shown in Figs. 3,4 and 5.
  • Fig. 9 shows the case where the valve is open under the action of the ink pressure and where the ink is flowing upwards.
  • the flow resistance to the ink passing through opening 908 between a valve 901 and a valve seat 906 needs to become sufficiently lower than the flow resistance of the auxiliary ink passage 912.
  • FIG. 10 A still another example of the fluid control means is shown in Fig. 10, in which the parts of the ink passage covered by the valve and the valve seat, as shown in Figs. 3, 4 and 5, are communicated by an auxiliary passage which is provided so as to bypass the valve and the valve seat.
  • the flow resistance to the ink passing through the opening 908 between the valve 901 and the valve seat 906 needs to be sufficiently lower than the flow resistance of the auxiliary ink passage 912.
  • the driving voltage to be applied to the piezoelectric transducer 11 or 101 will be described.
  • a pressure is generated in accordance with its voltage value ⁇ or with a quantity of deflection, and the magnitude of the pressure can be approximated as follows:
  • a and B are constants that are determined by the dimension and material of the piezoelectric oscillation plate
  • P is the pressure
  • ⁇ is the voltage
  • ⁇ o is the initial voltage
  • V is the capacity of the pressure chamber
  • the pressure occurring on the piezoelectric oscillation plate increases in proportion to the amplitude ( ⁇ - ⁇ o ) of the impressed voltage.
  • the pressure occurs in accordance with the equation (1) and the ink is caused to flow out from the pressure chamber.
  • the capacity of this pressure chamber decreases, the pressure also decreases progressively and when a predetermined voltage I) a is kept being applied, the pressure approaches zero.
  • the behaviour of the capacity change in this case is shown in Figure 11 a.
  • symbols b and c represent the behaviours when other voltages q) b and ⁇ c are applied, respectively.
  • the relation between these voltages is ⁇ a ⁇ b ⁇ c .
  • the deflection quantity of the capacity becomes greater with an increasing amplitude of the voltage.
  • the time required for deflection can be shortened by increasing the amplitude of the voltage if a predetermined capacity change is to be effected by this oscillation plate. It will be assumed the case in which the capacity is to be changed from V. to V a .
  • the width of this driving pulse is related with an ink droplet formation characteristic.
  • behaviour of the droplet formation will be considered by changing the width of the driving pulse.
  • the pulse width becomes greater and exceeds a predetermined width
  • the volume and initial speed of the ink droplet become constant irrespective of the pulse width. This is because the deflection of the pressure chamber reaches the saturation value in Figure 11.
  • this pulse width a large number of sub-droplets, that are called "satellite", of ink are formed in addition to the main ink droplet and cause recording problems.
  • the time required for the deflection to attain its maximum becomes about 0.2 msec in ordinarily available ink jet recording heads in this pulse width.
  • a pulse width is employed, it is not possible to obtain a high ink droplet-forming frequency.
  • a practical driving pulse is used one that shortens the application time and finishes the pulse application before the deflection attains its maximum.
  • the formation of the satellites can be eliminated, and the repetition frequency of the driving pulse can be enhanced since the pulse width is narrow.
  • FIG 12B shows the behaviour of the change in the capacity of the pressure chamber when the driving pulse having a pulse width, at which the capacity of the pressure chamber does not attain the maximum deflection quantity, such as shown in Figure 12A, is employed.
  • V o represents the initial capacity and V 1 does the saturation value when ⁇ 1 is impressed.
  • the capacity of the pressure chamber so changes as to asymptotically approach the saturation value V 1 and becomes V 2 at the time t 1 of finish of the ⁇ 1 application.
  • the deflection quantity of the pressure chamber capacity from V o is smaller than the deflection quantity up to the saturation value V i .
  • the ink droplet is formed by use of such a driving waveform as shown in Figure 12A, therefore, its repetition frequency becomes high, and if the application time of the driving pulse and the repetition frequency approach each other, a succeeding voltage is applied before the deflection of the pressure chamber is not capable of returning its initial value V o .
  • the pressure generated by the pressure chamber becomes smaller even if the same voltage is impressed. For this reason, the velocity of the jetted ink droplet and the volume of the droplet decrease. The decreases in the ink droplet velocity and the ink droplet volume may presumably be attributed to the slow action of the pressure chamber capacity in returning to its initial value.
  • the present invention contemplates to enhance the ink droplet forming a frequency by making it possible for the capacity of the pressure chamber to return to its initial value within a shorter period of time.
  • FIG. 13A shows an example of the driving pulse in accordance with the present invention.
  • the waveform is so arranged that it first changes from ⁇ 1 to ⁇ 1 at the time of jetting of the ink and when the deflection of the pressure chamber is to be returned to its initial state, it is set to ⁇ 2 having an amplitude in the opposite direction to ⁇ 1 with respect to ⁇ o before the voltage is returned to ⁇ o and is then allowed to return to ⁇ o .
  • the mode of change in the capacity of the pressure chamber when this driving waveform is applied is shown in Figure 13B.
  • the impressed voltage changes from ⁇ o to ⁇ 1 and attains the stage in which the ink droplet is about to be jetted, the capacity of the pressure chamber exhibits the same change as in Figure 12B.
  • the application time of ⁇ 2 in this description is the time required for the pressure chamber capacity to return to V o , some increases or decreases of the application time may be effected in practice in consideration of the force of inertia of the ink or the like.
  • This application time of ⁇ 2 varies in accordance with the magnitude of
  • the driving waveform shown in Figure 13A consists of two pulses continuously combined with each other, the former being for forming the ink droplet and the latter, for shortening the returning time of the capacity of the pressure chamber.
  • other driving waveforms may be employed, as well, such as one consisting of two spaced-apart pulses as shown in Figure 13C.
  • the present invention is not limited in particular to such a waveform. Namely, it is possible to use a waveform in which a predetermined time constant is applied to the rise and fall of the pulse, a triangular wave, a sine wave, a trapezoidal wave, and so forth. Namely, after the voltage for jetting the ink droplet is applied, the voltage is not merely returned to its initial value ⁇ o , but a voltage of an amplitude in the opposite direction to the voltage pulse for jetting the droplet is applied to the initial potential ⁇ o so that the capacity of the pressure chamber is capable of more rapidly returning to its initial value V o .
  • the waveform for this purpose is not limitative, in particular.
  • FIG 16 shows a representative of circuits for forming the driving waveform such as shown in Figure 13A.
  • a trigger pulse for forming the ink droplet is applied to a mono-multiple vibrator 211, there is produced a rectangular pulse 212.
  • This pulse width determines the ⁇ 1>1 application time of the driving pulse.
  • the pulse 212 is applied to a second mono-multiple vibrator, which is triggered by the rear end of the pulse and generates a rectangular pulse 214.
  • the pulse width of this pulse determines the ⁇ 1>2 application time of the driving pulse.
  • the rectangular pulses 212 and 214 are subjected to the amplitude adjustment by an amplitude control circuit 215 and are then applied to positive and negative input terminals of a differential amplifier 216, thereby yielding a driving signal 217.
  • FIG 16A shows an example of the driving waveform
  • Figure 16B shows an example of a compensating waveform.
  • Driving waveforms of the present invention synthesized from these waveforms are shown in Figures 16C, 16D and 16E.
  • Figure 17 shows an example of the circuit for forming these driving waveforms.
  • a trigger 210 signal is applied to a driving waveform forming circuit 218, a waveform such as shown in Figure 16A is produced as the output.
  • This trigger signal 10 is also applied to a delay circuit 219 and is applied to a compensating waveform forming circuit 219 after the passage of a predetermined time, thereby yielding the waveform such as shown in Figure 16B.
  • the force of returning the deflected piezoelectric oscillation plate to its original state becomes great by applying, after the formation of the ink droplet, a voltage having an amplitude in the opposite direction with respect to the voltage applied at the time of jetting the ink droplet and consequently, the returning time to the original state becomes shorter.
  • the delay time is selected in accordance with the signal response characteristic of the piezoelectric oscillation plate of the ink jetter printer to be employed and with the amplitude of the signal so that the time required for the capacity of the pressure chamber to return to its original state is shortened.
  • a voltage having an amplitude in the opposite direction to the driving voltage for jetting the ink with respect to the initial voltage is applied to the piezoelectric oscillation plate in order to allow the capacity of the pressure chamber to immediately return to its initial state after jetting of the ink.

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  • Particle Formation And Scattering Control In Inkjet Printers (AREA)
EP19810302728 1980-11-21 1981-06-17 Printer head for an ink-on-demand type ink-jet printer Expired EP0052914B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP16434380A JPS5787957A (en) 1980-11-21 1980-11-21 Ink jet recorder
JP164343/80 1980-11-21

Publications (2)

Publication Number Publication Date
EP0052914A1 EP0052914A1 (en) 1982-06-02
EP0052914B1 true EP0052914B1 (en) 1985-08-14

Family

ID=15791361

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19810302728 Expired EP0052914B1 (en) 1980-11-21 1981-06-17 Printer head for an ink-on-demand type ink-jet printer

Country Status (3)

Country Link
EP (1) EP0052914B1 (enrdf_load_stackoverflow)
JP (1) JPS5787957A (enrdf_load_stackoverflow)
DE (1) DE3171804D1 (enrdf_load_stackoverflow)

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US4433341A (en) * 1982-06-07 1984-02-21 Ncr Corporation Ink level control for ink jet printer
JPS59104950A (ja) * 1982-12-07 1984-06-18 Seiko Epson Corp インクジエツトヘツド駆動方法
JPS59110967A (ja) * 1982-12-16 1984-06-27 Nec Corp 弁素子の製造方法
DE3481902D1 (de) * 1983-08-31 1990-05-17 Nec Corp Bedarfsweise betriebener tintenstrahldruckkopf mit mitteln zur fluessigkeitskontrolle.
JPS6052352A (ja) * 1983-08-31 1985-03-25 Nec Corp インクジェット記録装置
GB2152877A (en) * 1984-01-16 1985-08-14 Howtek Inc Droplet ejector with control of fluid inlet to a reservoir
FR2618727B1 (fr) * 1987-07-31 1989-12-15 Ricard Claude Imprimantes a jet d'encre comprenant un collecteur d'aspiration et un collecteur connecte a un reservoir de stockage de gaz et vapeurs comprimes
US5500663A (en) * 1992-02-24 1996-03-19 Canon Kabushiki Kaisha Recording ink container with an air vent valve
US6692117B1 (en) 1997-07-14 2004-02-17 Owens-Illinois Closure Inc. Liquid containment and dispensing device with improved flow control valve
JPH11157092A (ja) * 1997-11-26 1999-06-15 Bridgestone Corp インクジェットプリンタ用部材の製造方法
DE69936797T2 (de) * 1998-06-16 2007-12-06 Seiko Epson Corp. Zuführventil
DE69941375D1 (de) † 1998-07-15 2009-10-15 Seiko Epson Corp Tintenzufuhreinheit
JP2007296675A (ja) * 2006-04-28 2007-11-15 Mimaki Engineering Co Ltd 流体吐出装置
JP6737327B2 (ja) * 2016-02-24 2020-08-05 コニカミノルタ株式会社 インクジェット記録装置及びインクジェットヘッドの駆動方法
US10974517B2 (en) * 2018-10-16 2021-04-13 Electronics For Imaging, Inc. High stability ink delivery systems, and associated print systems and methods

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US4007465A (en) * 1975-11-17 1977-02-08 International Business Machines Corporation System for self-cleaning ink jet head
DE2835262C2 (de) * 1978-08-11 1982-09-09 Dr.-Ing. Rudolf Hell Gmbh, 2300 Kiel Ansteuerung eines Tintenstrahl-Aufzeichnungsorgans
JPS5565568A (en) * 1978-11-11 1980-05-17 Ricoh Co Ltd Electrostrictive vibrator driving apparatus for ink jet printer
JPS5597677A (en) * 1979-01-16 1980-07-25 Seiko Epson Corp Driving circuit for ink jet printer head
JPS56139973A (en) * 1980-04-01 1981-10-31 Sharp Corp Ink jet recording

Also Published As

Publication number Publication date
JPH0329593B2 (enrdf_load_stackoverflow) 1991-04-24
DE3171804D1 (en) 1985-09-19
EP0052914A1 (en) 1982-06-02
JPS5787957A (en) 1982-06-01

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