Abstract: A material used for the actuator walls in an ink ejecting device, that are the walls of ink flow paths, are those in which the rate of change of the electromechanical coupling coefficient, with changes in temperature, is not greater than 3000 PPm/.degree. C. at temperatures of 20.degree. C. or less. Consequently, at a driving voltage that produces an ink drop ejection velocity of 5 m/s at 25.degree. C., the ink drop ejection velocity when driven at 10.degree. C. is at least 3 m/s, so that it is possible to obtain good printing quality.

Abstract: The present invention comprises an inkjet print head structure wherein the placement of the transducer electrodes in combination with the particular poling direction of the print head transducer material provides for an efficient combination of shear and normal mode actuation of the print head. The preferred print head structure may be formed as a densely packed linear series of substantially parallel ink channels interspaced between and adjacent to a series of substantially parallel air channels. Further, the present invention provides for a print head structure wherein structures in contact with ink are maintained at ground potential. The present invention provides for a method to manufacture a print head having an array of densely packed ink channels having the characteristics of reduced mechanical crosstalk.

Abstract: The effective length of an ink chamber extends from a front end of a manifold to a nozzle plate. Accordingly, the lengths of the manifolds formed in one or more cover plates are different, based on the different types of ink ejected from each ink chamber to change the lengths of the ink chambers. The effective lengths of the ink chambers for differently colored inks, such as cyan, black, yellow and magenta inks, are different. In particular, the effective lengths of the ink chambers in the yellow, magenta, cyan and black ink ejecting devices are different according to the different viscosities of the yellow, magenta, cyan and black inks, so that the volumes of ink droplets ejected from the ink ejecting devices are substantially equal to each other. As a result, the dot diameters of the different types of ink on a sheet of paper are substantially equal to each other, allowing beautiful color images to be formed.

Abstract: An ink-jet head comprising a plurality of sidewalls each imparting a pressure pulse to an ink pressurizing cell by means of shear mode deformation, and a front wall having a plurality of orifices. The ink in the ink pressurizing cells is ejected from the orifices. Each sidewall comprises a first wall section, a first electrode disposed thereon, an anisotropic adhesive disposed thereon, a second electrode disposed thereon, and a second wall section disposed thereon. Width of the first electrode is narrower than width of the first wall section, and the upper surface of the first wall section has first side areas which are not covered by the first electrode. Width of the second electrode is narrower than width of the second wall section, and the lower surface of the second wall section has second side areas which are not covered by the second electrode.

Abstract: Disclosed is an ink jet head which ejects an ink drop from an ink room throughout an orifice in response to deformation of piezoelectric member. The ink jet head has a non-piezoelectric member having a groove; a film provided on the non-piezoelectric member to cover the groove, the space formed between the groove and the film being uses as the ink room; a substrate provided opposing to the film; and a piezoelectric member having a first surface, the first surface contacting with the substrate corresponding to the ink room. A part of the first surface is fixedly connected with the substrate. The remaining part of the first surface is facing to the substrate, but is not fixedly connected.

Abstract: An ink droplet ejecting device includes first and second grooves formed on a piezoelectric ceramic plate. The positions of the first and second grooves are offset by a half pitch and are formed by cutting. A cover plate closes openings of the grooves at one side of the piezoelectric ceramic plate. The first grooves become gradually shallower toward one end surface of the piezoelectric ceramic plate to form flat surface portions so that the second grooves do not intercommunicate with a manifold of the cover plate. Further, first metal electrodes are formed on inner surfaces of the first grooves, and second and third metal electrodes are simultaneously formed on inner surfaces of the second grooves on the whole surface of the piezoelectric ceramic plate where the second grooves are formed.

Abstract: A page wide piezoelectric ink jet print engine and a method of manufacturing the same. The page wide ink jet print engine includes lower and upper body parts, each formed from piezoelectric material and having a plurality of generally parallel, spaced projections. Lower side surfaces of the projections of the lower body part are conductively mounted to corresponding bottom side surfaces of the projections of the upper body part to define a plurality of generally parallel, axially extending ink-carrying channels from which ink may be ejected.

Abstract: A drive method for an ink ejection device that cancels residual pressure fluctuations using a signal drive power source, wherein at time (b) a positive voltage V from a single power source is applied to an ink chamber 4b1 and other ink chambers 4 are connected to ground. Therefore, the volume of ink chamber 4b1 increases from a natural volume. At time (c), voltage V applied to the ink chamber 4b1 is stopped and a positive voltage V from the single power source is applied to the other ink chambers 4 so that the volume in the ink chamber 4b1 is reduced from the increased volume to an extent beyond the natural volume that causes an ink droplet to be ejected from the nozzle 12 of ink chamber 4b1. At timing (d), application of positive voltage V to the ink chambers 4c0, 4a1, 4c1, 4a2, 4b2, and 4c2 is stopped so that all the ink chambers revert to the natural volume.

Abstract: In an ink ejection device, second grooves having a width larger than the width of first grooves which are formed in a piezoelectric ceramic plate are formed on the end surface of the piezoelectric ceramic plate. A step portion is formed at an intersection portion between each of the first groove and each of the second grooves because the width of the second groove is larger than the first grooves. By depositing a conductive material from two directions above and to one side of the piezoelectric ceramic plate, driving electrodes and non-ejection channel lead wire electrodes are formed in the first grooves and on the inner surfaces of the slits by a shadow effect of the side walls on the second grooves.

Abstract: An ink jet printhead body has an ink filter structure integrally incorporated therein and operative to filter ink flowing into its internal ink receiving channels disposed between piezoelectrically deflectable interior wall portions of the body. In various illustrated embodiments of the printhead, the filter structure is defined by a series of photoetched micro filter passageways formed integrally in an outer side portion of the printhead body, a filter cavity formed in the outer side portion and receiving a separate photoetchable filter member in which photoetched micro filter passageways are formed, and a filter cavity formed in the outer side portion and receiving a separate mesh-type micro filter member.

Abstract: An ink jet head of an ink jet printer of a drop-on-demand type achieves mounting or connection between a driving electrode and an external electrode easily and surely and at the same time reduces revolution of a piezoelectric material during driving. Between the driving electrode with an insulating film and the external electrode is provided an electrical joining component containing electroconductive particles that are harder than the insulating film and that have a particle diameter larger than the thickness of the insulating film. At the bottom part of a slot in a piezoelectric material that forms an ink chamber and pressure chamber is provided a concave portion having a shape formed of combined at least two lines or surfaces. A part of a surface causing a revolution is converted to a component causing a shearing mode.

Abstract: Disclosed herein is an ink jet printer head including a substrate which includes a piezoelectric member polarized across a thickness thereof and a plate-like low-rigid member bonded to an upper surface of the piezoelectric member. The low-rigid member has a low permittivity and a rigidity lower than that of the piezoelectric member. The substrate has a plurality of grooves cut from an upper surface of the low-rigid member to a depth beyond a bonded surface between the low-rigid member and the piezoelectric member. A top plate is bonded to the upper surface of the low-rigid member so as to cover upper openings of the grooves, thereby defining a plurality of pressure chambers between the grooves and the top plate. A plurality of ink jet nozzles are provided so as to respectively communicate with the pressure chambers. A plurality of electrodes are formed on inner surfaces of the pressure chambers.

Abstract: To provide an ink ejecting device with high quality and excellent stability, three-layered laminated protective film is formed to cover an electrode which is formed on a ceramic element. The protective film is composed of an organic continuous film formed on the electrode as a first layer for covering surface unevenness. On the resultant smooth surface, a continuous inorganic film is formed as a second layer. Further, an organic layer is formed as a final layer.

Abstract: An ink droplet jet device having a piezoelectric ceramic plate is provided with ink chambers having partitions. The front half of each partition is opposite to the rear half in the direction of polarization. When a voltage is applied to the electrodes of a given partition, the front and the rear half thereof deform in the opposite directions because of their inverse directions of polarization. This prevents the introduction of air through the nozzles into the ink chambers adjacent to the activated ink chamber and the speed of printing is increased.

Abstract: In the embodiments of the simplified ink jet head described in the specification, a carbon plate is formed with orifice passages extending through the plate, pressure chambers on one side of the plate, flow-through passages on the other side of the plate and ink supply passages, and a piezoelectric plate having a conductive coating on the exposed side is affixed to the pressure chamber side of the carbon plate by a thin layer of epoxy adhesive. The conductive coating on the piezoelectric plate is photo-etched to produce an electrode pattern corresponding to the pattern of the pressure chambers in the carbon plate, and an orifice plate is affixed by a thin layer of epoxy adhesive to the opposite surface of the carbon plate with orifices aligned with the orifice passages in the carbon plate.

Abstract: An ink jet apparatus applies a drive voltage to electrodes formed on portions of side walls made of piezoelectric ceramics and varies the internal volumes of grooves adjacent to the side walls using the action of a deformation produced by a piezoelectric thickness/slip effect of the piezoelectric ceramics. Thereby, ink stored inside the grooves is ejected. According to such an ink jet apparatus, a void ratio of the piezoelectric ceramic is 10% or less, and an average crystal grain diameter of the piezoelectric ceramics is 10 .mu.m or less. Further, a variation in a ratio d.sub.15 /S.sub.E44 of a piezoelectric constant d.sub.15 of the piezoelectric ceramic to an elastic compliance S.sub.E44 thereof between the side walls falls within 4. A ratio H/W of a height H of each side wall to a width W thereof ranges from above 2 to below 9, and a ratio d.sub.15 /S.sub.E44 of a piezoelectric constant d.sub.15 of the piezoelectric ceramic to an elastic compliance S.sub.E44 thereof is 10 or more.

Abstract: The invention is a method of forming a conductive coating on a structural substrate. The method involves depositing a relatively non-conductive precursor material in a solution state on the structural substrate using inkjet apparatus. The solution is dried to leave a film. Then, the dried film is heated to a level at which a chemical (pyrolysis) reaction is triggered to convert the dried precursor material to a conductive material. The precursor solution can be dried in a manner which does not result in its transformation to the conductive state, as for example through the use of microwave apparatus. The precursor material can be applied on the substrate in such a manner as to control the conductivity of the coating and to provide a coating which exhibits one of uniform characteristics, discrete patterns, or gradient characteristics.

Abstract: An ink ejection device for ejecting ink comprises: a piezoelectric ceramic plate for defining an ink channel for containing ink, the piezoelectric ceramic plate deforming by application of an electric voltage thereto so as to change the volume in the ink channel and eject ink from the ink channel, the piezoelectric ceramic plate being formed by injection molding so that the piezoelectric ceramic plate having one surface with a surface roughness Rz (defined in Japanese Industrial Standard "JIS B 0601") of 1 .mu.m or less; and a metal electrode provided on the surface of the piezoelectric ceramic plate for applying the electric voltage to the piezoelectric ceramic plate.

Abstract: An ink ejecting device includes ink channels intercommunicating with slits and air channels intercommunicating with another slits. The ink channels and the air channels have a narrow shape with a rectangular cross-section, and all of the ink channels are filled with ink and the air channels are filled with air. An LSI chip applies a voltage V to a pattern conducting to metal electrodes positioned in air channels located at both sides of an ink channel from which the ink is to be ejected and connects the other patterns connected to metal electrodes in other air channels not adjacent the ejecting ink channel and a pattern conducting to the metal electrodes of the non-ejecting ink channels to a ground line. Therefore, the ink ejecting device of the above structure requires no insulation between ink and electrodes as the working electrodes do not contact the ink.

Abstract: An ink-ejecting device includes an actuator plate formed of piezoelectric material having ferroelectric properties, and a base plate formed of conductive material. After both plates are joined, plural grooves and partition walls for separating the grooves from one another are formed. First electrodes for applying a driving voltage are formed at respective size surfaces of the first grooves so as to extend from open portions of the grooves to middle portions thereof. The first electrodes are individually and independently connected to a controller. Further, second electrodes are formed on entire inner surfaces of respective second grooves, and all the second electrodes are connected to the controller through the base plate. According to an alternative embodiment, the ink-ejecting device further includes an intermediate plate formed of insulation material. After the three plates are joined, plural grooves and partition walls for separating the grooves from one another are formed.

Abstract: An ink ejecting apparatus is composed of a piezoelectric ceramics plate, a cover plate, and a nozzle plate. The piezoelectric ceramics plate is provided with a plurality of grooves. The cover plate is composed of a front plate and a rear plate. The rear plate is provided with a plurality of ink inlet holes and a manifold. The cover plate is bonded to the piezoelectric ceramics plate to define a plurality of ink chambers communicating with the manifold through the ink inlet holes and a plurality of air chambers that do not communicate with the manifold.

Abstract: A dual ink jet head has an actuator formed from a piezoelectric material that has side A and side B formed with a plurality of ink channels in total. To eject ink droplets from the nozzles in both side A and side B of the actuator using a single power source, electrode pairs for selected ink channels in side A are connected to the single power source and the remaining electrode pairs for non-selected ink channels in side A are disconnected from the single power source, and electrode pairs for selected ink channels in side B are disconnected from the single power source and the remaining electrode pairs for non-selected ink channels in side B are connected to the single power source. By so driving the actuator, ink droplets are ejected from the nozzles corresponding to the selected electrode pairs in both side A and side B.

Abstract: An actuator is made from a piezoelectric ceramic substrate and an alumina ceramic substrate. The alumina ceramic substrate is made from a material with a dielectric constant that is lower than the piezoelectric material from which the piezoelectric ceramic substrate is made. Using a diamond cutter blade, the actuator is formed with channel groove portions cut in the piezoelectric ceramic substrate, and sloping groove portions and shallow groove portions cut in the alumina ceramic substrate. Metal electrodes are vapor deposited at the inner surface of the shallow groove portions, on the side walls and a portion of the floor of the sloping groove portions, and on the side walls of the channel groove portions. Ink is ejected by deforming the side walls at the channel groove portions, which are made the piezoelectric ceramic substrate. Because the capacitance of the sloping groove portions and the shallow groove portions is small, only a small amount of energy need be inputted to eject ink droplets.

Abstract: A piezoelectric ink jet print head includes a body of piezoelectric material defining a plurality of parallel open topped channels having electrodes on opposite walls thereof. A top cover having a pattern of parallel conductors congruent with the open tops of the parallel channels is secured to the body by reflow soldering the conductors to the electrodes. The resulting solder bond is very stiff, thereby improving the performance of the print head, and the conductors provide convenient electrical contact to the electrodes.

Abstract: An ink jet print head includes pressure chambers divided by side walls formed at least partially of a piezoelectric member, voltage is applied to electrodes formed on surface of side walls, and jets ink in the pressure chambers through ink jets by causing deformation of shearing strain mode to the side walls. Each one of the side walls disposed on both sides of the pressure chambers has different operating characteristics. The volume of the ink to be jetted can be changed in three ways by selectively deforming either of the side walls of the pressure chamber from which the ink is to be jetted or by deforming both of the side walls of the pressure chamber simultaneously. Accordingly, gradation can be acquired by a simply constructed print head.

Abstract: An ink jet printer head has a piezoelectric ceramic element with a plurality of ink reservoirs wherein at least one side wall of each reservoir is made of a piezoelectric ceramic material and has an electrode for driving the piezoelectric ceramic element formed on the wall. The electrode is covered with an inorganic passive state protective film, and the protective film has a thickness of from 0.1 .mu.m to a value smaller than 1/8 of a thickness of the wall in maximum or a density of not smaller than 1.8 g/cm.sup.3. The protective film may be formed to cover all inner surfaces of each reservoir.

Abstract: Method for manufacturing a sidewall actuatable, high density channel array for an ink jet printhead. A first surface of a main body portion formed from an inactive material is conductively bonded to a first surface of a first intermediate body portion formed from an active material. A plurality of parallel grooves are then machined through the first intermediate body portion and part of the main body portion to form a plurality of channels separated by a corresponding plurality of sidewall actuators comprised of a first sidewall section formed from an inactive material and a second sidewall section formed from an active material. A top body portion is then conductively mounted to the intermediate body portion.

Abstract: A digital driver for an ink jet printhead and an associated method for selectively applying voltage to a piezoelectric sidewall actuator of the ink jet printhead. The digital driver includes positive and negative voltage sources, a first switching element having a first control input, a first voltage supply input connected to the positive voltage source, and a first output, and a second switching element having a second control input, a second voltage supply input connected to the negative voltage source, and a second output connected to the first output to provide a single output connected to the piezoelectric sidewall actuator. By asserting the first control input for a first time period, the first switching element generates a positive voltage pulse at the single output to displace the sidewall actuator from a rest position to a first position.

Abstract: A droplet jet apparatus using an actuator serves as an electromechanical transducer that acts as an energy generator used for the ejection of droplets. The actuator has a plurality of grooves and walls made of piezoelectric material that define liquid channels and pressure chambers. Drive electrodes are formed on both sides of each wall. The drive electrodes formed on both sides of each piezoelectric wall fall within an electrode depth range of .+-.30% or less with respect to a set value of an electrode depth d extending in the wall height direction. Thus, the droplets can be stably jetted for a long period of time by setting the electrode depth to a proper value.

Abstract: In a piezoelectric type ink jet head, a plurality of pressure chambers are separated into n groups each having dummy pressure chambers at opposite ends. An increased spacing between ejection nozzles resulting from the dummy pressure chambers is compensated for by inclining the nozzle openings within each of the groups. The ink jet head is driven in a time sharing manner.

Abstract: An organic material is used as the protective film in the ink ejecting printer head with the surface roughness Ra of the protective film is set to be no greater than 3 .mu.m. Accordingly, the segregation of ink components is suppressed to ensure a smooth flow of ink. As a result, the variations in the volume of the ink droplets ejected is reduced and the ejecting stability is improved. Therefore, the ink ejecting printer head having such a protective film that is excellent in protection also improves the stability of the ejected ink droplets and can be manufactured at a low cost.

Abstract: A multi-channel array droplet deposition apparatus has a base sheet comprising a layer of piezo-electric material poled normal thereto, an array of parallel, open-topped droplet liquid channels provided by upstanding channel separating walls formed in the layer, electrodes on channel facing surfaces of the walls, a channel closure sheet bonded to the walls, nozzles respectively communicating with the channels and a droplet liquid supply connecting with the channels, the closure sheet having an array of parallel conductive tracks thereon paced at intervals corresponding with the channel spacing and located parallel to and opposite the channels and bonds, which preferably are solder bonds, mechanically and electrically connect each track to the electrodes of the channel facing walls of the channels opposite thereto and seal the closure sheet to the channels.

Abstract: Multi-channel droplet deposition apparatus of the kind having an array of parallel channels (1-11) with which respective nozzles and common ink supply communicate and in which electrically actuable devices (21-31) are located in relation to said channels to impart energy pulses to selected channels for effecting droplet ejection therefrom is operated by applying energy pulses to selected channels of the array and channels in the vicinity of the selected channels the amplitudes of which depend on the value of the compliance ratio of the channel walls to the droplet liquid and which together produce a pressure distribution in the channels to which they are applied which both effects droplet ejection from only said selected channels and is substantially free from pressure crosstalk between said selected channels or between said selected channels and other channels of the array.

Abstract: A switched digital drive system is used to actuate an ink jet printhead having a spaced, parallel series of internal ink receiving channels opening outwardly at front ends thereof through ink discharge orifices formed in the printhead body. The channels are laterally bounded by a spaced series of piezoelectrically deflectable internal sidewall sections of the printhead body interdigitated with the channels. The drive system includes a series of electrical actuation leads each connected to a different one of the sidewall sections, and dual transistor switch structures connected in the leads with each switch, in turn, connected to positive and negative DC voltage sources.

Abstract: Method for manufacturing a sidewall actuatable, high density channel array for an ink jet printhead. A first surface of a main body portion formed from an active material is conductively bonded to a first surface of a first intermediate body portion formed from an active material. A plurality of parallel grooves are then machined through the first intermediate body portion and part of the main body portion to form a plurality of channels separated by a corresponding plurality of sidewall actuators comprised of a first sidewall section formed from an active material and a second sidewall section formed from an active material. A top body portion is then conductively mounted to the intermediate body portion.

Abstract: In a shear mode type ink jet head, nozzle holes are disposed at substantially central portions of channels formed between barriers of piezoelectric material, and common ink reservoirs are provided at both ends of the channels. In one embodiment, two kinds of channels having different depths are formed in alternating succession on a board made of piezoelectric material. Channels of one depth are used as dummy channels and are kept empty, and channels of the other depth are filled with ink and the ink can be ejected from the channels through nozzle holes.

Abstract: A digital driver for an ink jet printhead and an associated method for selectively applying voltage to a piezoelectric sidewall actuator of the printhead. The digital driver includes positive, negative and neutral voltage sources, a first switching element having a first control input, a first voltage supply input connected to the positive voltage source and a first output, a second switching element having a second control input, a second voltage supply input connected to the negative voltage source and a second output, and a third switching element having a third control input, a third voltage supply input connected to the neutral voltage source and a third output. The first, second and third outputs are connected together to provide a common output for connection to the piezoelectric sidewall actuator.

Abstract: A droplet jet device for use in an ink jet printer. The device has a bottom ceramics plate into which parallel grooves for storing ink are cut. A covering plate is either fixedly or slidably mounted over the grooved side of the ceramic plate to enclose the grooves. The sidewalls of the grooves have electrodes mounted thereon. One end of each groove is connected to an opening serving as an ink jet and the other end is connected to a ink source. The ink jets may be smaller grooves connecting the grooves to a print face of the bottom ceramics plate or may be ends of smaller grooves in the cover plate, one of the smaller grooves in the cover plate partially overlapping a corresponding groove in the ceramics base plate. When a current is applied to selected electrodes, the associated walls are deformed by a piezoelectric effect to compress the groove and eject an ink droplet from the ink jet.

Abstract: An ink jet printhead includes of a lower body part having a base section and a plurality of generally parallel spaced projections extending upwardly therefrom and an upper body part having a top section and a corresponding plurality of generally parallel spaced projections extending downwardly therefrom. The top sides of the lower body projections are conductively mounted to the bottom sides of the upper body projections to form sidewalls which define a plurality of ink-carrying channels. Strips of a conductive adhesive mount the lower and upper body projections together and a controller is electrically connected to the strips to selectively impart either a positive, zero, or negative voltage to each strip. The lower body part is formed using a piezoelectric material poled in a first direction generally perpendicular to the channels and the upper body part is formed using a piezoelectric material also poled in the first direction.

Abstract: In the ink droplet jet device of the present invention having a plurality of jet units for jetting an ink in an ink channel from jet nozzles formed on a nozzle plate by changing a volume in the ink channel by using a piezoelectric transducer, two plates are bonded for forming the ink channel. Two piezoelectric ceramic plates having grooves whose widths are larger than widths of the ink channel are provided. Alternatively, one piezoelectric ceramic plate and non-piezoelectric materials can be provided on which the same grooves are formed. When the interval between adjoining ink channels becomes very small to enable an increase in a number of jet nozzles communicating with the ink channels in order to make an image formed by the jetted ink droplet an image of high resolution, the groove processing of the piezoelectric ceramic plate is facilitated because the width of grooves to be ground is very wide in comparison with a conventional device, thereby reducing manufacturing cost.

Abstract: A method of multi-tone printing employs a drop-on-demand printing apparatus for depositing ink droplets on printing element areas of a substrate which is movable relatively to the apparatus. The droplets are deposited from an array of channels on the substrate which is movable relatively to the channels. The channels length and nozzle location and dimensions afford each channel with a high longitudinal resonant frequency and energy pulses are supplied to selected channels at or near the resonant frequency of the channels to deposit from each selected channel in the corresponding printing element area of the substrate a number of drops equal to the number of pulses applied thereto, the number of pulses applied being dependent on the tone of printing required. Single channel and color versions of the invention are also disclosed.

Abstract: An ink jet head is disclosed for use with a drop-on demand type printer, and includes an insulating base, a plurality of elongated barriers projecting upwardly from the base so as to form a plurality of slots between the barriers, a plurality of nozzle holes communicating with the slots, and electrodes formed on the side walls of the elongated barriers. Voltage can be applied to the various barriers through the electrodes in order to cause deflection of the barriers and a corresponding reduction in the cross-sectional area of selected slots, so as to force ink contained in the slots to be jetted through the nozzle holes. In order to provide a uniform ink jet intensity from the outermost slots relative to the inner slots, dummy slots can be formed outwardly of the outermost active slots by providing dummy barriers outwardly of the outermost active barriers. In addition, the nozzle holes are formed in a nozzle plate. The nozzle plate can either be mounted against the ends of the slots, or atop the base.

Abstract: An array of ink droplet ejection devices for use in a drop-on-demand type printer includes a piezoelectric transducer and a cover plate. Both the piezoelectric transducer and the cover plate are formed with a plurality of grooves in parallel to one another. The groove-formed surfaces of the piezoelectric transducer and the cover plate are engaged with each other to form a plurality of ink channels. The piezoelectric transducer and the cover plate are in surface contact with each other at the side surfaces of the respective protrusions. The protrusion of the piezoelectric transducer is uni-directionally deformable to be substantially out of surface contact with the protrusion of the cover plate. With such a construction, the individual ink channels can be operated independently of one another and ink droplets can be simultaneously ejected from the adjacent ejection devices.