EP0716926B1 - Tête d'impression à jet d'encre du type gouttelettes à la demande à canal allongé pour éjection de gouttelettes en direction orthogonale à des vitesses de fonctionnement améliorées - Google Patents

Tête d'impression à jet d'encre du type gouttelettes à la demande à canal allongé pour éjection de gouttelettes en direction orthogonale à des vitesses de fonctionnement améliorées Download PDF

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Publication number
EP0716926B1
EP0716926B1 EP19950309100 EP95309100A EP0716926B1 EP 0716926 B1 EP0716926 B1 EP 0716926B1 EP 19950309100 EP19950309100 EP 19950309100 EP 95309100 A EP95309100 A EP 95309100A EP 0716926 B1 EP0716926 B1 EP 0716926B1
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EP
European Patent Office
Prior art keywords
channels
series
length
body portion
ink jet
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Expired - Lifetime
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EP19950309100
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German (de)
English (en)
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EP0716926A2 (fr
EP0716926A3 (fr
Inventor
Lowell M. Good
David B. Wallace
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Compaq Computer Corp
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Compaq Computer Corp
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Publication of EP0716926A3 publication Critical patent/EP0716926A3/fr
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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
    • B41J2/135—Nozzles
    • B41J2/14—Structure thereof only for on-demand ink jet heads
    • B41J2/14201—Structure of print heads with piezoelectric elements
    • B41J2/14209—Structure of print heads with piezoelectric elements of finger type, chamber walls consisting integrally of piezoelectric material
    • 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
    • B41J2202/00—Embodiments of or processes related to ink-jet or thermal heads
    • B41J2202/01—Embodiments of or processes related to ink-jet heads
    • B41J2202/18—Electrical connection established using vias

Definitions

  • the present invention generally relates to ink jet printhead apparatus and, more particularly, to a length-mode drop-on-demand ink jet printhead for ejecting orthogonally directed droplets, i.e., droplets ejected in a direction generally orthogonal to the printhead's orifice plane, at improved operating speeds.
  • Ink jet printing devices use the ejection of tiny droplets of ink to produce an image. As such devices produce highly reproducible and controllable droplets, a droplet may be printed at a location specified by digitally stored image data.
  • One type of ink jet printing device is generally referred to as a "drop-on-demand" type ink jet printing device.
  • droplets of ink are ejected from the printhead in response to a specific command related to the image to be produced.
  • the quality of the image produced by an ink jet printing device is commonly measured by the resolution of the device in dots per inch (or "dpi").
  • dpi dots per inch
  • the resultant images produced thereby will more closely resemble full or continuous tone images.
  • To increase the resolution of drop-on-demand ink jet printing devices considerable efforts have been made to form as many individual channels in as small a space as possible.
  • "high density" drop-on-demand ink jet printheads generally characterized by a channel density greater than 125 channels per linear inch, have become increasingly common.
  • such ink jet printheads may be further classified as "length-mode" ink jet printheads.
  • the longitudinal extension of the channels are bounded by an ink ejection orifice on one end and by an interconnection with an ink supply on the other.
  • this longitudinal extension creates a single dominant acoustic resonance frequency which is proportional to the length of the channels.
  • the length of this longitudinal extension of the channels acts as limit on the maximum operating frequency of the printhead. More specifically, in order to prevent operating frequency induced variations in the volume and/or velocity of droplets ejected by a channel of a length-mode ink jet printhead, the channel must be limited to operating frequencies below the second or third subharmonic, i.e. f RES /2 or f RES /3 of the resonant frequency f RES . Thus, if an increase in the operating speed of a length-mode ink jet printhead is desired, the length of the channels may be reduced appropriately.
  • capillary pressure induces replenishing ink to flow towards the orifice of the channel to compensate for the losses in ink due to droplet ejection.
  • This capillary pressure is controlled by various factors which include orifice geometry, orifice material, surface tension and the shape and position of the ink meniscus. As the rate at which droplets are ejected from the channel is increased, the rate of ink flow in the channel and the pressure drop within the channel due to viscous losses increase.
  • EP-A-0648161 disclosed a page wide ink jet printhead having a series of elongated grooves formed in a block of active piezoelectric material. A corresponding series of channels are then formed by covering the grooves with a sheet of polymer material. Rather than placing the ink ejection orifices at one end of the resultant channels, the open ends of the channels are dammed and ink ejection orifices are ablated in the sheet of polymer material which forms the roof of the channels. However, as the orifices are formed proximate to one end of the channels, the resonant frequency of the channels are not significantly affected by placement of the orifices along the roof thereof. Accordingly, the frequency at which a selected channel may be actuated will not vary appreciably due to placement of its ink ejection orifice along the roof of the channel.
  • EP-A-0595654 discloses a drop-on-demand type ink jet head.
  • a length-mode ink jet printhead comprising:
  • each one of the series of channels has a length to height ratio of greater than 10:1 and, more preferably, each one of the series of channels has a length to height ratio of between about 25:1 and about 250:1.
  • the ink ejection orifices may be positioned such that each one communicates with the corresponding one of the channels midway between the first acoustic pressure wave reflection interface and the second acoustic pressure wave reflection interface.
  • the ink supply means may be comprised of an ink supply coupled to the first interior conduit at the front side surface of said first manifold plate.
  • the second acoustic pressure wave reflection interface includes a second manifold plate having a front side surface, a rear side surface coupled to the rear side surface of the body portion, a second manifold in communication with each one of the channels and grooved in the rear side surface and a second interior conduit which extends between the second manifold and the front side surface.
  • the ink supply means may include an ink supply coupled to the first interior conduit at the front side surface of the first manifold plate and to the second interior conduit at the front side surface of the second manifold plate and the means for imparting an acoustic pressure wave to ink contained in a selected one of the series of channels includes means for applying an electric field to the first and second sidewalls bounding the selected channel to cause a piezoelectric deflection thereof.
  • the body portion of the length-mode ink jet printhead includes a lower body section having an upper side surface and a series of generally parallel spaced projections extending longitudinally along the upper side surface between the front and rear side surfaces and upwardly therefrom.
  • a bottom side surface of an intermediate body section may be conductively mounted to a top side surface of a corresponding one of the lower body projections.
  • a lower side surface of an inactive upper body section in which the ink ejection orifices are formed may be conductively mounted to a top side surface of each one of the intermediate sections.
  • the lower body section is formed of an active piezoelectric material poled in a first direction.
  • the means for applying an electric field to the first and second sidewalls may further comprise means for applying an electric field between the bottom side surface of the intermediate body section of the first sidewall and the bottom side surface of the intermediate body section of the second sidewall.
  • each of the intermediate sections are formed of an active piezoelectric material poled in the first direction.
  • the means for applying an electric field to the first and second sidewalls may further comprise means for applying a first electric field between the bottom and top side surfaces of the intermediate body section of the first sidewall and a second electric field between the bottom and top side surfaces of the intermediate body section of the second sidewall.
  • a length-mode ink jet pinhead comprising:
  • each one of the series of channels has a length to height and length to width ratios of greater than 10:1 and, thereof, each one of the series of channels has length to height and length to width ratios of between about 25:1 and about 100:1.
  • length-mode drop-on-demand ink jet printhead 10 constructed in accordance with the teachings of the present invention will now be described in greater detail.
  • length-mode it is intended to refer to an ink jet printhead dimensioned such that the ratio of the length of the channel to the height of the sidewalls is greater than 10:1 and the ratio of the length of the channel to the width of the channel is also greater than 10:1.
  • length-mode ink jet printheads are typically dimensioned to have a channel length to sidewall height ratio of between about 25:1 and about 250:1.
  • the length-mode ink jet printhead 10 may be dimensioned to have a channel length of 15 mm, a sidewall height of 100 ⁇ m, a channel width of 90 ⁇ m and a sidewall width of 80 ⁇ m.
  • the ink jet printhead 10 is comprised of first and second body parts 12, 14, having respective top and bottom surfaces 12a, 12b and 14a, 14b.
  • the first and second body parts 12, 14 are similarly sized along their respective length and width dimensions. Relative to the height dimension, however, the second body part 14 is shorter than the first body part 12.
  • both the first and second body parts 12, 14 are formed of a piezoelectric material, for example, PZT, poled in direction P although, in an alternate embodiment of the invention, the first body part 12 may be formed of an inactive material.
  • Layers 16, 18, 20 of conductive material are formed along the top side surface 12a of the first body part 12, the bottom side surface 14b of the second body part 14 and the top side surface 14a of the second body part 14, respectively, for example, using a conventional metal deposition process.
  • the first and second body parts 12, 14 are aligned along respective front surfaces 12c, 14c and the layers 16, 18 are conductively bonded to each other using a layer of conductive adhesive (not shown in FIG. 1).
  • a series of generally parallel grooves which downwardly extend through the conductive layer 20, the second body part 14, the conductive layer 18, the layer of conductive adhesive, the conductive layer 16 and a portion of the first body part 12, and which longitudinally extend from the front side surfaces 14c, 12c to back side surfaces 14d, 12d, are formed, preferably using a machining or other sawing process.
  • the first sidewall part 24 includes a strip 28 of conductive material formed from the conductive layer 16 during the grooving process and is integrally formed with the first body part 12 on one side thereof.
  • the second sidewall part 24 includes lower and upper strips 30 and 32 of conductive material located on opposite sides thereof and respectively formed from the conductive layers 18 and 20 during the grooving process.
  • the strips 28 and 30 are conductively mounted to each other by a strip 34 of conductive adhesive formed from the layer of conductive adhesive, again during the grooving process.
  • a orifice plate 36 having a layer 38 of conductive material formed on a lower side surface 36b thereof is conductively mounted to the strips 32 to form a series of ink-carrying channels 40 from the grooves. More specifically, a layer 42 of conductive adhesive is applied to the layer 38 of conductive material, front and rear side surface 36c, 36d of the orifice plate 36 are aligned with the front and rear side surface 14c, 14d of the second body part 14 and the orifice plate 36 and the second body part 14 mated.
  • a series of ink ejection orifices 44 are formed in the orifice plate 36.
  • Each orifice 44 extends from a first opening 44b located along the bottom side surface 36b of the orifice plate 36 to a second, narrower, opening 44a located along a top side surface 36a of the orifice plate 36.
  • the orifices 44 are located along a line generally parallel to, and midway between, the front and rear side surfaces 36c, 36d of the orifice plate 36.
  • each orifice 44 By mounting the orifice plate 36 to the second body part 14, the opening 44b of each orifice 44 is placed in communication with a corresponding one of the channels 40 at the general center of the longitudinal extension of the channel 40, i.e. midway between front and rear side openings 40c, 40d of the channel 40. It is contemplated that a laser ablation process may be used to form the orifices 44 in the orifice plate 36. Preferably, the orifices 44 are formed after the orifice plate is mounted onto the second body part 14, for example, in accordance with the method set forth in U.S. Patent No. 5,208,980 to Hayes.
  • the ink jet printhead 10 is coupled to an ink supply system which includes an ink supply 46, a front manifold plate 48 and a rear manifold plate 50.
  • Each of the channels 40 is filled with ink received from the ink supply system connected with the front and rear openings 40c, 40d of each of the channels 40.
  • each horizontally opposed pair of the piezoelectric sidewall actuators 22 is piezoelectrically deflectable into and out of their associated channel 40 to force ink (in droplet form) outwardly through the orifice 44 associated with the actuated channel 40.
  • Each manifold plate 48, 50 includes an interior side surface 52, 56 and a manifold 54, 58 formed along the interior side surface 52, 56.
  • the interior side surface 52 of the front manifold plate 48 is mounted to the front side surfaces 12c, 14c of the first and second body parts 12, 14 such that the manifold 54 is in communication with the front opening 40c of each one of the channels 44.
  • the interior side surface 56 of the rear manifold plate 50 is mounted to the rear side surfaces 12d, 14d of the first and second body parts 12, 14 such that the manifold 58 is in communication with the rear opening 40d of each one of the channels 44.
  • Each manifold plate 48, 50 further includes an internal conduit 60 which extends between the exterior side surfaces 64, 66 and the manifolds 54, 58.
  • the ink supply system further includes an external conduit 68 connected to the internal conduit 60 of the front manifold plate 48 and the internal conduit (not visible) of the rear manifold plate 50.
  • the front and rear manifold plates 48, 50 provide first and second acoustic pressure wave reflection interfaces for the channels 40. It is contemplated that the front and rear manifold plates 48, 50 may provide the desired acoustic pressure wave reflection interfaces by either providing a large change in cross-sectional area in the transition between the channels 40 and the front and rear manifolds 54 and 58, or by being formed of a material having a much greater compliance than the material forming the walls of the channels 40, or by both. This type of acoustic pressure wave relection interface would have a reflection coefficient approaching -1.0 so that the resonance behavior is similar to the resonance behavior of an open-open organ pipe.
  • each conductive strip 28 may be electrically connected to a conductive pin 72 which extends through the first body part 12 and projects from the bottom side surface 12b thereof.
  • a driver board 70 having a plurality of pin-receiving apertures (not shown) for receiving the portions of the pins 72 projecting from the lower side surface 12b may be snap-mounted onto the bottom side surface 12b of the first body part 12.
  • the driver board 70 should include a controller for issuing control signals to actuate selected ones of the piezoelectric sidewall actuators 22 and a series of switching structures capable of generating a positive or negative voltage at an output thereof in response to instructions issued by the controller.
  • the driver board 46 is snap-mounted onto the lower body part 12, each output of a switching structure should become electrically connected with one of the pins 72.
  • a snap-in driver board 70 may be used to provide a separate electrical connection to every conductive strip 28.
  • the piezoelectric sidewall actuators 22 in which the conductive strips 28 are embedded may be deflected relative to the channels 40 bounded by the selected piezoelectric sidewall actuator 22 to impart a pressure pulse thereto which effects the ejection of a droplet of ink therefrom.
  • the portion of the pins 72 extending through the first body part 12 should be electrically isolated therefrom, for example, using a layer of insulative material (not shown), to prevent the pins 72 from shorting the electric fields which causes selected piezoelectric sidewall actuators 22 to deflect.
  • the driver board 70 may be omitted and the conductive strips 28 interconnected with a controller (not shown) by means of conductive electrical leads (also not shown) which extend through either of the front manifold plate 48 or the rear manifold plate 50.
  • conductive electrical leads also not shown
  • any such conductive electrical leads which extend through the manifold plates 48, 50 do not need to be insulated.
  • a voltage waveform 74 also referred to as an echo pulse waveform, which includes primary and echo portions 74a, 74b for generating a pressure wave in a selected channel 40 of the ink jet printhead 10 to cause the ejection of an orthogonally directed droplet of ink therefrom
  • a rest state 76 during which a rest state voltage is applied to the conductive strip 28 and the piezoelectric sidewall actuator 22 remains in a undeflected rest position, the voltage waveform 74 begins a rapid rise 78 at time T 1 in the voltage applied to the conductive strip 28.
  • the voltage rise 78 causes the piezoelectric sidewall actuator 22 to begin to move towards a first, outwardly deflected position, thereby producing an expansive acoustic pressure wave in the channel 40 partially defined thereby.
  • the resonant frequency f RES for the channels 40 of the ink jet printhead 10 is equal to the wavespeed of the acoustic pressure waves generated in the channels 40 divided by the length of the channels 40.
  • the length of the channels 40 is determined from the distance from the orifice 44 to the acoustic pressure wave relection interfaces provided by the front and rear manifolds 48 and 50.
  • the resonant frequency f RES for the channels 40 is L/2 where L is the length of the channels 40.
  • the acoustic wave generated by the deflection of the piezoelectric sidewall actuator 22 is a longitudinal wave having a fluid velocity directed parallel to the direction of propagation.
  • a pressure gradient K see FIG. 3
  • kinetic energy i.e., the velocity of an orthogonally directed droplet ejected from the orifice 44 or other movement of the ink meniscus at the orifice 44.
  • the direction of the fluid velocity produced during the conversion process is determined by the pressure gradient, and as the pressure gradient is orthogonal to the orientation of the orifice 44, the direction of the kinetic energy produced during the conversion process is determined by orientation of the orifice 44, which, in the embodiment of the invention disclosed herein, is perpendicular to the longitudinal extension of the channel 40. Accordingly, droplets ejected from the orifice 44 will travel in a direction generally orthogonal to the orifice plate 36 and the channel 40.
  • the orifice 44 effectively divides the channel 40 into a first (or forward) part and a second (or rearward) part. Both the forward and rearward part of the channel 40 has a discrete resonant frequency proportional to the length of that part of the channel. However, if the orifice 44 is located at the midpoint of the channel 40, this resonant frequency is the same for both parts of the channel 40 and is one-half the resonant frequency for a length-mode channel having an orifice at one end thereof.
  • the expansive acoustic pressure wave produced by the outward deflection of the piezoelectric sidewall actuator 22 begins to propagate both forwardly and rearwardly through both the forward and rearward parts of a channel 40 partially defined thereby.
  • the rearwardly propagating portion produced in the forward part of the channel 40 and the forwardly propagating portion produced in the rearward part of the channel 40 will encounter the pressure gradient at the orifice 44 and be converted into kinetic energy.
  • the voltage waveform 74 enters a primary dwell state 80 which extends from time T 2 to time T 3 .
  • the voltage is held constant at the first value to hold the piezoelectric sidewall actuator 22 in the deflected position.
  • the forwardly propagating pressure wave in the forward part of the channel 40 and the rearwardly propagating pressure wave in the rearward part of the channel 40 will have reflected off the interfaces with the ink supply 46 located at the front and rear openings 40c, 40d of the channel 40 and returned to their origination point.
  • the voltage waveform 74 begins a rapid fall 82 during which the voltage drops below the rest voltage (thereby ending the primary portion 74a and beginning the echo portion 74b of the echo pulse 74) to a second, lower value at time T 4 .
  • the voltage applied to the conductive strip 28 drops to the second value, thereby causing the piezoelectric sidewall actuator 22 to move, from the first, outwardly deflected position, past the rest position, and into a second, inwardly deflected position which compresses the channel 40.
  • the piezoelectric sidewall actuator 22 By compressing the channel 40, the piezoelectric sidewall actuator 22 imparts a second pressure wave into the channel 40 which reinforces the rearwardly propagating reflected pressure wave in the forward part of the channel 40 and the forwardly propagating reflected pressure wave in the rearward part of the channel 40.
  • the voltage waveform 74 enters an echo dwell state 84 which extends from time T 4 to time T 5 .
  • the voltage is held constant at the second value to hold the piezoelectric sidewall actuator 22 in the second, channel compressing, deflected position.
  • the reinforced pressure waves will propagate towards the orifice 44 where the pressure waves now have sufficient strength to overcome the surface tension of the meniscus of the ink when converted into kinetic energy.
  • the voltage waveform 74 will begin a second rise 86 which will return the voltage waveform 74 to the rest state 76 at time T 6 .
  • the piezoelectric sidewall actuator 22 will move from the second, channel compressing, deflected position to the rest position, thereby imparting a negative pressure wave into the channel 40.
  • This negative pressure wave acts as an active pull-up which prematurely terminates the droplet formation process by the rearwardly propagating reinforced pressure wave in the forward part of the channel 40 and the forwardly propagating reinforced pressure wave in the rearward part of the channel 40.
  • the voltage waveform 74 remains at this state to allow the pressure pulse within the channel 40 to dissipate over time.
  • the rest, first and second voltages may be 0, +20 and -20 volts, respectively, the rise, fall, and return times may all be 5 ⁇ sec, the dwell time may be 15 ⁇ sec and the echo dwell time may be 30 ⁇ sec. It is further contemplated that the rise, fall and return times may be effectively reduced to zero if a suitably configured digital switching system is incorporated as part of the drive system for the ink jet printhead 10.
  • FIG. 5 an illustrative actuation of a channel 40a to drive a quantity of ink therein, in droplet form, outwardly through the associated ink discharge orifice 44 will now be described in greater detail.
  • its horizontally opposed left and right sidewall actuators 22 L and 22 R are (at time T o in FIG. 5) in initial, laterally undeflected (or "rest") positions such as that illustrated in FIG. 2.
  • the voltage waveform 74 is applied to the conductive strip 28 L separating the lower and upper sidewall parts 24 L , 26 L of the piezoelectric sidewall actuator 22 L while a second voltage waveform of opposite polarity, relative to the rest state voltage 76, to the voltage waveform 74 is simultaneously applied to the conductive strip 28 R separating the lower and upper sidewall parts 24 R , 26 R of the piezoelectric sidewall actuator 22 R to initiate the channel actuation cycle.
  • the left conductive strip 28 L would have the voltage rise 78 imposed thereon during the time interval T 1 - T 2 , reaching the primary dwell state 80 where a constant positive voltage is applied thereto, at time T 2 .
  • the right conductive strip 28 R would have an equal negative voltage drop imposed thereon during the time interval T 1 - T 2 , reaching a negative dwell state where a constant negative voltage (relative to the rest voltage) is applied thereto at time T 2 .
  • the piezoelectric sidewall actuators 22 L and 22 R are outwardly deflected away from the channel 40a being actuated and into the outwardly adjacent channels (not shown), thereby imparting respective compressive pressure pulses to the outwardly adjacent channels and expansive pressure pulses to the channel 40a which propagate forwardly and rearwardly in both the forward and rearward parts of the channel 40.
  • the rearwardly propagating portion of the acoustic pressure wave imparted to the rearward part of the channel 40a reflects off the rear manifold plate 50 of the ink jet printhead 10 and begins to propagate forwardly in the channel 40a while the forwardly propagating portion of the acoustic pressure wave imparted to the forward part of the channel 40a reflects off the front manifold plate 48 and begins to propagate rearwardly in the channel 40b.
  • the forwardly propagating portion of the acoustic pressure wave imparted to the rearward part of the channel 40a and the rearwardly propagating portion of the acoustic pressure wave imparted to the forward part of the channel 40a are dissipated at the orifice 44.
  • the positive voltage pulse 70 transmitted to the conductive strip 28 L and the corresponding negative, relative to the rest state voltage 54, voltage pulse on the conductive strip 28 R are terminated and the conductive strip 28 L has the voltage fall 60 imposed thereon during the time interval T 3 - T 4 , reaching the echo dwell state 62 where a constant negative, relative to the rest state voltage 54, voltage is applied thereto, at time T 4 .
  • the conductive strip 28 R would have an equal positive voltage rise imposed thereon during the time interval T 3 - T 4 , reaching a positive echo dwell state where a constant positive voltage is applied thereto at time T 4 .
  • Such inward deflection of the actuators 22 L and 22 R elevates the potential energy stored as ink pressure within the channel 40a to an extent sufficient to initiate droplet formation due to the kinetic energy produced when the reinforced acoustic pressure waves arrive at the orifice 44.
  • the piezoelectric sidewall actuator 22 L has the second voltage rise 64 imposed thereon during the time interval T 5 - T 6 , returning to the rest state 76 at time T 6 .
  • the piezoelectric sidewall actuator 22 R would have an equal negative, relative to the rest state voltage 76, voltage fall imposed thereon during the time interval T 5 - T 6 , returning to the rest state at time T 6 .
  • the piezoelectric sidewall actuators 22 L and 22 R are outwardly deflected back to their respective rest positions.
  • the outward deflection back to the rest position cancels out forwardly propagating pressure waves within the rearward part of the actuated channel 40a and rearwardly propagating pressure waves within the forward part of the actuated channel 40a, thereby causing the premature termination of the formation of the ink droplet within the actuated channel 40a such that the volume of the droplet to be ejected therefrom is determined by the time at which the sidewall actuators 22 L and 22 R are driven back to the rest position.
  • the sidewall actuators 22 L and 22 R are then held at the rest state voltage 76 until any remaining pressure waves within the actuated channel 40a subside over time.
  • the resonant frequency of a length-mode ink jet printhead in which both the front and rear ends are dammed and the orifices are positioned midway between the front and rear ends is one-half the resonant frequency of a traditionally designed length-mode ink jet printhead having an open front end.

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Claims (15)

  1. Tête d'impression à jet d'encre (10) du type à canaux allongés, comprenant :
    une partie formant corps (12,14) possédant un paroi latérale extérieure, une paroi avant (12c,14c), une paroi arrière (12d,14d) et une série de canaux en général parallèles (40) s'étendant entre la paroi avant et la paroi arrière, chacun des canaux étant délimités par des première et seconde parois latérales intérieures, chacune des première et seconde parois latérales intérieures étant formées au moins partiellement d'un matériau piézoélectrique actif (16,18,20);
    la partie formant corps possédant une série d'orifices d'éjection d'encre (44) formés en elle, chaque orifice de la série d'orifices d'éjection d'encre traversant une plaque à orifices (36) jusqu'à l'un correspondant de la série de canaux;
    des moyens (48) pour envoyer de l'encre à la série de canaux;
    des moyens (22) pour appliquer une onde de pression acoustique à une encre contenue dans un canal sélectionné de la série de canaux pour injecter une gouttelette d'encre hors de l'orifice d'éjection d'encre en communication avec le canal sélectionné;
    une première interface (48) de réflexion d'ondes de pression acoustiques couplée à la paroi avant (12c,14c) de la partie du corps, la première interface de réflexion d'ondes acoustiques de pression réfléchissant des ondes de pression qui se propagent vers l'avant et sont produites par la série de canaux; et
    une seconde interface (50) de réflexion d'ondes acoustiques de pression couplée à la paroi arrière (12d, 14d) de la partie principale du corps, la seconde interface de réflexion d'ondes de pression acoustiques réfléchissant des ondes de pression se propageant vers l'arrière et produites dans la série de canaux;
       caractérisé en ce que la première interface de réflexion d'ondes acoustiques de pression comporte en outre une première plaque à collecteur (48) possédant une surface avant, une surface arrière (52) couplée à la paroi avant de la partie formant corps (12,14), un premier collecteur (54) en communication avec chacun des canaux (40) et creusé en forme de rainure dans la surface arrière, et un premier conduit intérieur (60) qui s'étend entre le premier collecteur et la surface avant de la première plaque à collecteur.
  2. Tête d'impression à jet d'encre (10) à canaux allongés selon la revendication 1, dans laquelle chaque canal de la série de canaux (40) possède un rapport longueur/hauteur supérieur à 10:1.
  3. Tête d'impression à jet d'encre (10) à canaux allongés selon la revendication 1, dans laquelle chaque canal de la série de canaux (40) possède un rapport longueur/hauteur compris entre environ 25:1 et environ 250:1.
  4. Tête d'impression à jet d'encre (10) à canaux allongés selon l'une quelconque des revendications précédentes, dans laquelle chacun des orifices d'éjection d'encre (44) communique avec le canal correspondant parmi les canaux (40), situés à mi-chemin entre la première interface (48) de réflexion des ondes de pression acoustiques et la seconde interface (50) de réflexion des ondes de pression acoustiques.
  5. Tête d'impression à jet d'encre (10) à canaux allongés selon l'une quelconque des revendications précédentes, dans laquelle les moyens d'alimentation à jet d'encre (46) comprennent en outre une alimentation en encre couplée au premier conduit intérieur (60) au niveau de la surface latérale avant de la première plaque à collecteur (48).
  6. Tête d'impression à jet d'encre (10) à canaux allongés selon l'une quelconque des revendications précédentes, dans laquelle la seconde interface (50) de réflexion d'ondes de pression acoustique comporte en outre une seconde plaque à collecteur (50) possédant une surface arrière, une surface avant couplée à la surface arrière (12d,14d) de la partie formant corps, un second collecteur (58) en communication avec chacun des canaux (40) et creusé en forme de rainure dans la surface avant et un second conduit intérieur (60) qui s'étend entre le second collecteur et la surface arrière de la seconde plaque à collecteur.
  7. Tête d'impression à jet d'encre (10) à canaux allongés selon la revendication 6, dans laquelle l'alimentation en encre (46) est couplée au second conduit intérieur (60) sur la surface arrière de la seconde plaque à collecteur (50).
  8. Tête d'impression à jet d'encre (10) à canaux allongés selon l'une quelconque des revendications précédentes, dans laquelle les moyens (22) pour appliquer une onde de pression acoustique à l'encre contenue dans l'un sélectionné de la série de canaux (40) comprennent en outre des moyens pour appliquer un champ électrique aux première et seconde parois latérales délimitant le canal sélectionné pour provoquer la déviation piézoélectrique des première et seconde parties latérales.
  9. Tête d'impression à jet d'encre (10) à canaux allongés selon l'une quelconque des revendications précédentes, dans laquelle la partie formant corps comporte :
    une section de corps inférieure (14) possédant une surface latérale supérieure et une série de parties saillantes espacées qui d'une manière générale sont parallèles et s'étendent longitudinalement le long de la surface latérale supérieure entre les surfaces latérales avant et arrière et vers le haut à partir de ces dernières, chacune des parties saillantes inférieures du corps comportant une surface supérieure;
    une série de sections de corps intermédiaires (16,18,20), chaque section de la série de corps intermédiaires possédant une surface inférieure montée de façon conductrice sur la surface supérieure d'une partie correspondante parmi les parties saillantes inférieures du corps; et
    une section de corps supérieure (12), dans laquelle les orifices d'éjection d'encre (44) sont formés, la section de corps supérieure étant formée d'un matériau inactif et possédant une surface latérale inférieure montée de façon conductrice sur une surface latérale de chacune de la série de sections intermédiaires (16,18,20).
  10. Tête d'impression à jet d'encre (10) à canaux allongés selon la revendication 9, dans laquelle la section de corps inférieure (14) est formée d'un matériau piézoélectrique actif polarisé dans une première direction, et dans laquelle les moyens (22) servant à appliquer un champ électrique aux première et seconde parois latérales délimitant le canal sélectionné (40) pour provoquer une déviation piézoélectrique des première et seconde parois latérales comprennent en outre des moyens pour appliquer un champ électrique entre la surface inférieure de la section de corps intermédiaire de la première paroi latérale et la surface inférieure de la section de paroi intermédiaire de la seconde paroi latérale.
  11. Tête d'impression à jet d'encre (10) à canaux allongés selon la revendication 9, dans laquelle chacune des sections intermédiaires (16,18,20) est formée d'un matériau piézoélectrique actif polarisé dans une première direction, et dans laquelle les moyens (22) servant à appliquer un champ électrique aux première et seconde parois latérales délimitant le canal sélectionné pour provoquer une déviation piézoélectrique des première et seconde parois latérales comprennent en outre des moyens pour appliquer le premier champ électrique entre les surfaces inférieure et supérieure de la section de corps intermédiaire de la première paroi latérale, et une seconde section de corps intermédiaire de la première paroi latérale et un second champ électrique entre les surfaces inférieure et supérieure de la section de paroi intermédiaire de la seconde paroi latérale.
  12. Tête d'impression à jet d'encre (10) à canaux allongés selon la revendication 9, dans laquelle la section de corps inférieur (14) est formée d'un matériau piézoélectrique actif polarisé dans une première direction, chacune des sections intermédiaires (16,18,20) sont formées d'un matériau piézoélectrique actif polarisé dans la première direction, et dans laquelle les moyens pour appliquer un champ électrique aux première et seconde parois latérales délimitant le canal sélectionné pour provoquer une déviation piézoélectrique des première et seconde parois latérales comprennent en outre des moyens pour appliquer un premier champ électrique entre la surface inférieure de la section de corps intermédiaire de la première paroi latérale et la surface inférieure de la section de corps intermédiaire de la seconde paroi latérale, un second champ électrique entre les surfaces inférieure et latérale de la section de corps intermédiaire de la première paroi latérale et un troisième champ électrique entre la surface inférieure et la surface supérieure de la section de paroi intermédiaire de la seconde paroi latérale.
  13. Tête d'impression à jet d'encre à canaux allongés, comprenant :
    une partie de corps inférieure (14) formée d'un matériau piézoélectrique actif polarisé dans une première direction, la partie de corps inférieure possédant une surface latérale avant, une surface latérale arrière, une surface latérale supérieure et une série de parties saillantes espacées, qui sont d'une manière générale parallèles et s'étendent longitudinalement le long de la surface latérale supérieure entre les surfaces avant et arrière et vers le haut à partir de là, chacune des parties saillantes inférieures du corps possédant des première et seconde surfaces latérales et une surface supérieure;
    une série de parties de corps intermédiaires (16, 18,20) formées d'un matériau piézoélectrique actif polarisé dans la première direction, chaque partie de la série de parties de corps intermédiaires possédant une paroi avant, une paroi arrière, des première et seconde surfaces latérales, une surface supérieure et une surface inférieure, la surface inférieure étant montée de façon conductrice sur la surface supérieure d'une partie correspondante parmi les parties saillantes inférieures du corps;
    une partie de corps supérieure (12) formée d'un matériau inactif, la partie de corps supérieure possédant une surface supérieure, une surface inférieure montée de façon conductrice sur la surface supérieure de chacune des parties de corps intermédiaires et une série d'orifices d'éjection d'encre (44);
    la surface supérieure de la partie de corps inférieure, les première et seconde surfaces latérales des parties saillantes inférieures du corps, les première et seconde surfaces latérales des parties de corps intermédiaires et la surface latérale inférieure de la partie de corps supérieure définissant une série de canaux (40) disposés d'une manière générale en parallèle et qui s'étendent entre la surface avant et la surface arrière des parties de corps inférieure et intermédiaire;
    chacun des canaux (40) étant délimité par des première et seconde parois latérales, chaque paroi latérale comprenant l'une des parties saillantes de corps inférieures et la partie de corps intermédiaire montée sur la partie saillante de corps inférieure;
    chaque orifice de la série d'orifices d'éjection d'encre (44) s'étendant entre la surface supérieure et un canal correspondant de la série de canaux;
    une première interface (48) de réflexion d'ondes de pression acoustiques pour réfléchir les ondes de pression se propageant vers l'avant et produites dans la série de canaux;
    une seconde interface (50) de réflexion d'ondes acoustiques de pression pour réfléchir des ondes de pression se propageant vers l'arrière et produites dans la série de canaux;
    des moyens (22) pour appliquer une onde de pression acoustique à l'encre contenue dans l'un sélectionné de la série de canaux (40) pour éjecter une gouttelette d'encre à partir de l'orifice d'éjection d'encre (44) en communication avec le canal de sélection, les moyens d'application comprenant des moyens pour appliquer un premier champ électrique entre la surface inférieure de la partie de corps intermédiaire de la première paroi latérale et la surface inférieure de la partie de corps intermédiaire de la seconde paroi latérale, des moyens pour appliquer un second champ électrique entre les surfaces inférieure et supérieure de la partie de corps intermédiaire de la première paroi latérale et des moyens pour appliquer un troisième champ électrique entre les surfaces inférieure et supérieure de la partie de corps intermédiaire de la seconde paroi latérale;
       caractérisée en ce que la première interface de réflexion d'ondes acoustiques de pression comprend une première plaque à collecteur (48) possédant une surface avant, une surface arrière couplée aux parois avant de la partie de corps inférieure, aux parties de corps intermédiaires et à la partie de corps supérieure, un premier collecteur (52) de communication avec chacun des canaux et usiné dans la surface arrière d'un premier conduit intérieur qui s'étend entre le premier collecteur et la surface avant de la première plaque à collecteur,
       en ce que la seconde interface de réflexion d'ondes de pression acoustiques comprend une seconde plaque à collecteur (50) possédant une surface avant, la surface avant étant couplée aux surfaces arrière de la partie de corps inférieure, à la série de parties de corps intermédiaires et à la partie de corps supérieure, le second collecteur (58) étant en communication avec chacun des canaux et étant usiné dans la surface avant d'un second conduit intérieur qui s'étend entre le second collecteur et l'arrière de la seconde plaque à collecteur;
       en ce que chacun des orifices d'éjection d'encre (44) communique avec celui correspondant des canaux (40), qui est à mi-chemin entre la surface arrière de la première plaque à collecteur et la surface arrière de la seconde plaque à collecteur; et
       en ce qu'une alimentation en encre (46) est couplée au premier conduit intérieur sur la surface avant de la première plaque à collecteur et au second conduit intérieur au niveau de la surface avant de la seconde plaque à collecteur.
  14. Tête d'impression à jet d'encre à canaux allongés selon la revendication 13, dans laquelle chacun de la série de canaux possède un rapport longueur/hauteur inférieur à 10:1.
  15. Tête d'impression à jet d'encre à canaux allongés selon la revendication 13, dans laquelle chaque canal de la série de canaux possède un rapport longueur/hauteur compris entre 25:1 et environ 250:1.
EP19950309100 1994-12-16 1995-12-14 Tête d'impression à jet d'encre du type gouttelettes à la demande à canal allongé pour éjection de gouttelettes en direction orthogonale à des vitesses de fonctionnement améliorées Expired - Lifetime EP0716926B1 (fr)

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US35772594A 1994-12-16 1994-12-16
US357725 2003-02-03

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EP0716926A2 EP0716926A2 (fr) 1996-06-19
EP0716926A3 EP0716926A3 (fr) 1997-04-16
EP0716926B1 true EP0716926B1 (fr) 2002-03-13

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Publication number Priority date Publication date Assignee Title
EP1029678B1 (fr) * 1999-02-17 2008-04-09 Konica Corporation Tête d'impression à jet d'encre
JP6377444B2 (ja) * 2014-08-01 2018-08-22 株式会社東芝 インクジェットヘッド

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US4887100A (en) 1987-01-10 1989-12-12 Am International, Inc. Droplet deposition apparatus
US5227813A (en) * 1991-08-16 1993-07-13 Compaq Computer Corporation Sidewall actuator for a high density ink jet printhead
US5471231A (en) * 1992-10-30 1995-11-28 Citizen Watch Co., Ltd. Ink jet head

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EP0716926A2 (fr) 1996-06-19
EP0716926A3 (fr) 1997-04-16
DE69525821D1 (de) 2002-04-18
DE69525821T2 (de) 2002-09-19
JPH08230187A (ja) 1996-09-10

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