CA1219776A - Fluid jet print head - Google Patents
Fluid jet print headInfo
- Publication number
- CA1219776A CA1219776A CA000425460A CA425460A CA1219776A CA 1219776 A CA1219776 A CA 1219776A CA 000425460 A CA000425460 A CA 000425460A CA 425460 A CA425460 A CA 425460A CA 1219776 A CA1219776 A CA 1219776A
- Authority
- CA
- Canada
- Prior art keywords
- print head
- fluid
- transducers
- elongation
- frequency
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- 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
- B41J2/18—Ink recirculation systems
- B41J2/185—Ink-collectors; Ink-catchers
-
- 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
- B41J2/015—Ink jet characterised by the jet generation process
- B41J2/02—Ink jet characterised by the jet generation process generating a continuous ink jet
- B41J2/025—Ink jet characterised by the jet generation process generating a continuous ink jet by vibration
-
- 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
- B41J2/015—Ink jet characterised by the jet generation process
- B41J2/02—Ink jet characterised by the jet generation process generating a continuous ink jet
- B41J2/03—Ink jet characterised by the jet generation process generating a continuous ink jet by pressure
-
- 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
- B41J2/07—Ink jet characterised by jet control
- B41J2/105—Ink jet characterised by jet control for binary-valued deflection
Landscapes
- Particle Formation And Scattering Control In Inkjet Printers (AREA)
Abstract
Abstract of the Disclosure A fluid jet print head includes an elongated body having a length substantially greater than its other dimensions and defining a fluid receiving reservoir in one end. The body defines at least one nozzle from which fluid, supplied under pressure to the reservoir, emerges as a fluid filament. The print head includes a support for engaging the body intermediate its ends. Further, the print head includes a pair of piezoelectric transducers, bonded to the exterior of the print head body, for alternately elongating and contracting in phase in the direction of elongation of the print head body. This causes mechanical vibration of the body and break up of the fluid filament into drops. Alternately, the piezoelectric transducers may be driven out of phase such that the print head body flexes.
Description
7~i ~1DF 002 P2 -l-FLUID JET PRINT H~AD
Background of the Invention The present invention relates to a fluid jet print head and, more particularly, to a print head and method for generating at least one stream of drops in which construction and operation of the print head ar~
facilitated.
Jet drop printers and coating devices operate by generating streams of small drops of ink or coating fluid and controlling the deposit of the drops on a print receiving medium. Typically, the drops are electrically charged and then deflected by an electrical field. The drops are formed from fluid filaments which emerge from small orifices. The orifices communicate with a fluid reservoir in which fluid is maintained under pressure.
Each El~1id Eilament tends to break apart at its tip to form a stream of drops. In order to deELect drops acc~lrateLy by means of an el.ectrical field and produce selective cleposition of the drops on the print receiving nlc~diuln, iL i~. r1ece~sary lor th~ drop~q to be sub.qtantial1y uniEorm in size and ln interdroE~ spacin~ within each stream. 'L'he brealc up of the fiLaments into streams of drops is Eacilitated by mechar1ical vibration of some portion or all of the print head structure in a process termed "stimulation".
One prior art stimulation technique, as shown in tl.S. patel1t No. 3,739,393, is~ued June 12, 1973, to Lyon et al, is to provide the fluid oriEices in a relatively thin, flexible wall of the fluid reservoir and to stimulate this wall, known as an "orifice plate", by causing a series of bending waves to travel along the MDF 002 P2 -2- ~2~6 plate. This technique results in substantially uniform drop size and spacing but the timing of break up of the fluid filaments varies along the length of the orifice plate.
Another approach is to vibrate the entire print head, including the ink manifold structure and the orifice plate structure, together. This is shown in U.S. patent No. 3,586,907, issued June 22, 1971, to Beam et al. Such an arrangement will necessarily fatigue the print head mounting structure, since the mounting structure experiences the same vibrations which are applied to the manifold and the orifice plate. Further, the amplitude and phase of the vibratory motion are difficult to control at the frequencies commonly used for jet drop printer operation.
A further approach to filament stimulation is disclosed in U.S. patent No. 4,095,232, issued June 13, 197~, to Cha. U.sing the tecllllique discl.osed in this patent, stimulators mounted in the upper portion oE a Eluid reservoir generate pressure waves which are transmitted downward through the Eluid. ~ach stimulator ir)cludes a pair oE piezoelectric crystal.s which vibrate in pllase and which are mounted on opposite sides oE a mountillg plate which is coincident with a nodal plane. A
reaction mass is positioned at the end oE each stimulator opposite the stimulation member which is coupled to the fluid. The reaction mass ensures that the nodal plane is properly positioned.
In British patent specification 1~22388, a print head is disclosed in which a piezoelectric crystal forms one wall of a single-jet ink jet print head. When a drop MDF 002 P2 -3- ~2~9~
is to be emitted from the orifice, the piezoelectric transducer is electrically actuated, causing it to distort and thereby forcing a drop from the orifice.
In British patent specification 1293980, published October 25, 1972, and U.S. patent No. 4,19~,643, issued April 15, 1980, to Cha et al, print heads are disclosed in which a pair of piezoelectric crystals are bonded to opposite sides of a support plate. A print head manifold structure is bonded to one of the piezoelectric crystals and a counterbalance is bonded to the other of the crystals. The weight of the counterbalance is selected so as to offset the weight of the print head manifold. By this balanced arrangement, the support plate is placed in a nodal plane when tlle two piezoelectric transducers are energized in svnchronism. It will be appreciated, however, that the construction Oe such a print head is relatively complicated and, Eurther, that it is diEEiclllt to design such a print heacl to be resonant at a desire.l Erequellcy. r~'he print head m~lst be tuned subsecluell~ to construction, therecore, such that the resonant Erequency oE t~e print llead equals che desired operating Erequency.
Flnally, in U.S. pa~ell~ No. 3,972,47~, issued ~ugust 3, 1976, to i~eur, an ink drop writing system is showll in whicll a vibratin-3 nozzle is used to produce a stream of drops. The length oE the nozzle is selected so that its mechanical resonallt frequency is much higher than the frequency at which it is driven. The nozzle, configured as a tube, is surrounded by a piezoelectric ring which, when electrically driven, provides radial contraction and expansion of the tube.
MDF 002 P2 -4~ 977~
There is a need for an improved fluid jet print head in which uniform in-phase stimulation may be provided for a plurality of jet drop streams, in which mounting oE
the print head is facilitated, and in which construction and design of the print head are simplified.
Summary_of the Invention A fluid jet print head for generatinq at least one stream of drops comprises an elongated print head body, the length of the body between first and second ends thereof being substantially greater than its other dimensions. The body defines a fluid receiving reservoir in its first end and at least one orifice communicating ~ith the fluid receiving reservoir. Fluid is supplied to the reservoir under pressure by appropriate means such that it emeryes from the reservoir to Eorm a fluid stream. ~ transducer means is mountec~ on the exterior of the body and extends a substantial distance a:Long the body in the direction of elongation Erom adjacent the support means toward both the Eir~st ancl second ends oE the body.
Ihe tran-;~lucer means is responsive to an electrical drivincJ sigrla:L Eor changillg dimcnsion in the direction of elongatiorl oE the body, thereby causing mechanical vibrcltion oE the body and break up oE the f:luid stream into a stream oE drops.
rile transducer means compri.ses a pair oE
piezoelectric transducers bonded to opposite sides of the hody and extending in the direction of elongation from points adjacent the first end to points adjacent the second end of the body. The piezoelectric transducers provide alternate lengthening and contraction of the elongated print head body in the direction of elongation of the body.
l9~;
The transducer means further comprises means for electrically connecting the pair of transducers in parallel, whereby the transducers operate in phase so as to produce vibration which is in a direction substantially parallel to the direction of elongation of the elongated print head body. A support means for the print head engages the print head body intermediate and substantially equidistant from its first and second ends.
Alternatively, the transducer means may comprise means for electrically connecting the transducers so that they operate out of phase, thus producing flexure waves.
The support means for the print head engages the print head body a distance from each end of the body approximately equal to .23 of the overall length of the body.
F'or vibration parallel to the direction of elongation, the support means may comprise a pair of mountinq Elanges, each inteqrally formed with the print head body, and being relatively thin. The flanges extend Erom the elongated print heacl hocly on opposite si.des thereoE ancl are substantially equidis~ant from the first ancl secolld encls o~ the bocly such that they support the bocly alonc3 a noclaL plane. Alternatively, the support means may compri.se a pair of support screws which engage the body at opposite sides thereof at points substantially ecTuidistant from the first and second ends of the print head body.
The print head body includes means defining a slot in the first end thereof and orifice plate means, attached to the means defining a slot, and forming the fluid receiving reservoir therewith. The orifice plate ~IDF 002 P2 -6- ~2~
means may define a plurality of orifices for production of a plurality of drop streams. The print head body may further define a Eluid supply opening and a fluid outlet opening communicating with the slot. The fluid jet print head may further lnclude fluid conduit lines connected to the fluid supply opening and the fluid outlet opening.
The fluid conduit lines are formed of a material having a substantially different vibrational impedance than the print head body, whereby the conduit lines do not provide a substantial power loss. The fluid conduit llnes may, for example, be made of a poLymer material.
The fluid jet print head may further include means for applying an electrical driving signal of a frequency substantially equal to fo = C/2L, where L is the dimension of the body in the direction of elongation, and C is the speed of sound through the body. In this case the fluid ~et print head is driven at a Erequency approximating its mechanical resonant: Erequency.
r~or Elexure wave vibration, the tran.sducers are driven at a Erecl-lency Fo ~ /L2~ wh(?re a is the transverse thickness oE the print head body and ~ -1.7.
In this case, two nodal mounting axes are established a distance equal to approximately .23 oE the length oE the print heacl body/ centerecl betwe~en the transducers.
The mettlod Eor stimulating the break up of a fluid stream emanatLng from at least one orifice communicating with the fluid reservoir in a fluicl jet print head includes the steps oE:
(a) providing an elongated print head which defines the reservoir and the orifice at one end thereof;
(b) applying fluid under pressure to the reservoir so as to produce fluid flow through the orifice;
(c) supporting the print head at points in a plane substantially equidistant from the ends of the elongated print head and normal to the direction of elongation of the print head; and (d) alternately elongating and contracting the print head substantially at the resonant frequency of the print head, whereby the print head is supported in a nodal plane and the stream is eEfectively stimulated to break up into drops.
The resonant frequency of the print head may be substantially equal to the resonant frequency o~ the fluid stream. The print head may be elongated and contracted by means of piezoelectric trans-lucers bonded to its exterior.
The stream may also be stimulated by operatincJ the transducers ouk of phase, thereby causing ~lexure of the print head. In this stimuLation mode, the print head is mounted at points which are a distance Erom each end which are approximately equal to ~23 times the length of the print head.
Accordingly, it is an object oE the present invention to provide a fluid jet print head for generating one or more streams of drops in which the print head includes an elongated body which is driven to elongate and contract in the direction of MDF 002 P2 -8- ~9~7~
elongation of the body; to provide such a print head and method in which the print head is driven by means of thin piezoelectric transducers bonded to the print head exterior; and to provide such a print head in which support for the print head is provided in a nodal plane.
Other objects and advantages of the invention will be apparent from the following description, the accompanying drawings and the appended claims.
Brief Description of the Drawings .
Fig. 1 is an exploded view, illustrating a first embodiment of the fluid jet print head of the present invention;
Fig. 2 is a plan view oE the print head oE
Fig. 1, with the orifice plate removed;
Fig. 3 is a side view oE the print head oE
Fig. l with the electrical drive circuitry illustrated;
Fig. 4 is an enlarc3ecl partial sectional view, taken c~enerally along line 4-4 in Fig. 2;
Fic~. 5 is a graph, use~ul in explaining the operation oE the print hea~3 oE the present invention;
Flig~ 6 is a graph, useful in e~plaining operation oE the print head of the present invention.
Fig. 7 is a schematic diagram illustrating driving circuitry for the fluid print heacl; and F`ig. ~ is a side view oE a second embodiment of the fluid jet print head of the present invention.
Detailed Description of the Preferred Embodiments The present invention relates to a fluid jet print head oE the type which may be used for ink jet printing, coating, textile dyeing, and other purposes. As is known, such devices typicall~
operate by electrically charging the drops in one or more jet drop streams and, thereafter, deflecting the trajectories of some of the drops by means of electrical fields. In order to produce the stream or streams of drops, fluid is typically applied to a fluid reservoir under pressure such that it then flows through one or more orifices or nozzles which communicate with the reservoir. The fluid emerges from the orifices as fluid filaments which, i~ left undisturbed, would brealc up somewhat irregularly into drops of varying size and spacing. It is not possible to charge and deflect such nonuniform drops accurately and, as a consequellce, jet drop devices have typically applied mechanical stimulation in some Eashion to the f]uid Eilaments so as to cause break up oE the filame~nts into clrops of generally uniEorm size allcl spacin~ at a deqired clrop break up frequency.
A first ernbocliment of the print head of the present invention is shown in Figs. 1-4. ~rhe print head generally includes an elongated print head body lO, the Length of which, L, is substantially greater than its other dimensions a and b. The body lO
includes an orifice plate 12 and a block of material 14. The body lO defines a fluid receiving re,ervoir 16 in its first end, and at least one and preferably ~DF 002 P2 -10-a number oE orifices 18 which are arranged in a row across orifice plate 12. The orifice plate 12 is bonded to block 14 of material, such as stainless steel by means oE a suitable adhesive. Block 14 defines a slot 20 which, in conjunction with orifice plate 12 defines the reservoir 16. The block 14 further defines a fluid supply opening 22 and a fluid outlet opening 24, both of which communicate with the slot 20.
The print head further includes means for supplying fluid to the reservoir 16 under pressure such that fluid emerges from the ori~ices 1~ as 1uid Eilaments which then break up into streams of drops. This includes a pump 26 which receives fluid from a tank 28 and delivers it, via fluid conduit line 30, to the reservoir 16. A conduit 32 is connected to fluid outlet 2~ such that fluid may be removecl from the re~qervoir L6 at shut down of the print head or during cross-Elushill~ oE the reservoir L6. As wlll become apparent, the end oE the print head to which conduits 30 and 32 are attached, as well as the opposite encl of the print head, i;
subjected to mechanical vibrations which cause the fluid filalnents to break up into streams of drops of uniform si~e and spacing. The conduits 30 and 32 are selected from among a number of materials, such as a polymeric material, which have a vibrational impedance substantially different from that oE the stainless steel block 14. As a consequence, power loss through the conduits 30 and 32 and the resulting damping of the vibrations are minimized.
r~lDF 002 P2 ~ 77~
The print head further includes support means, such as mounting flanges 34. Flanges 34 are relatively thin and are integrally formed with the block 14. The flanges 34 extend from opposite sides of the elongated print head body 10 and are substantially equidistant from the first and second ends of the body. As a result, the flanges may be used to support the body 10 in a nodal plane. The flanges 34 are therefore not subjected to substantial vibration.
The print head further comprises a transducer means, including thin piezoelectric transducers 36 and 38. The transducers are bonded to the exterior oE the body of block 14 and extend a substantial distance along the body in the direction of elongation thereof, from ad~aeent the support means toward both the first and seconcl ends of the body. The transdueers 36 and 3~ respond to an electrical drivlncJ sicJnal, provided by power supply ~0 on lin~ ~2, by eharlcJiny dimension, thereby causing meehallieal vibration oE the body and break up oE the Elllid streams into streams of drops.
'I'ht~ piezoeleetric transclueers 36 and 3~
have electrically eonduetive eoatings on their outer ~urfaces, that is the sur~aces away frorn the print head block 1~, whieh define a first eleetrode for each such transducer. The metallie print head bloek 14 typieally grounded, provides the seeond electrode for eaeh of the transdueers. The piezoeleetric transducers are seleeted such that when driven by an a.e. drive signal, they alternately expand and ~IDF 002 P2 -12~
contract in the direction of elongation oE the print head. As may be seen in Fig. 3, transducers 36 and 38 are electrically connected in parallel. The transducers are oriented such that a driving signal on line 42 causes them to elongate and contract in unison. Since the transducers 36 and 3~ are bonded to the block 14, they cause the block to elongate and contract, as well.
If desired, an additional piezoelectric transducer 44 may be bonded to one of the narrower sides o e the print head to provide an electrical output potential on line 46 which fluctuates in correspondence with the elongation and contraction of the print head block 14. The amp]itude of the signal on line 46 is proportional to the amplitude oE the mechanical vibration of the block 14.
rrhe mechanism by which the Eirst embodiment Oe the print head oE the present invention functions may be deseribc-.~d as Eollows. rl'hc elongated print heacl bocly is som~what analogous to an ordinary hellcal speing. If such a spring i5 COmpreS5ed alld then quickly released, it will oscillate about its center at a frequency eO, callec~ its Eundamental longitudinal resonant Erequency. In this eondition, both ends of the spring move toward and away from the center of the spring, while the center remains at rest. Therefore, if one fixes the center of the spring and repeats the above described operation, the spring will oscillate in the same manner at the Erequency Fo.
MDF 002 P2 -13- ~Z~97~6 The steel block 14 which forms a part of the print head body can be considered to be a very stiff spring. If properly mechanically stimulated, it may therefore be held at its center, as by flanges 34, while both ends of the block 14 alternately move toward and away from the center.
Since the center of the block lies in a nodal plane, the flanges 34 are not subjected to substantial vibration and the support for the print head does not interfere with its operation. As the end of the print head body 10 which defines the fluid receiving reservoir 16 is vibrated, the vibrations are transmitted to the fluid filaments which emerge frorn the orifices 16, thus ca~lsing substantially simultaneous uniform drop break up. Note that the reservoir 16 is small in relation to the overall size oE the block 14 and is centered in the end of the block. As a consequence, the reservoir 16 does not interE~re si~niEicantly with the vibration of the bLock ]4, nor a~Eect the resonant ~requency of the print llead substantially.
rt'he resonant frequency of the block 14 can ~enerally be said to be given by ~0 = C/2L =VE/P/2L
where C is the speed of sound through the print head block 14 material, L is the length of the print head body in the direction of elongation, E is the modulus of elasticity of the material forming block 14 and p is the density of the material forming the block 14. Preferably the print head is designed to operate at or near its resonant frequency, and this ~DF 002 P2 -14~ ~2~9~7~
frequency, in turn, is selected within an appropriate fluid jet stimulation frequency range, e.g., 50KH~ to ]OOKH~.
By providing a pair of piezoelectric transducers 36 and 38 on opposite sides of the block 14, the block 14 is elongated and contracted without the flexure oscillations which would otherwise result if only one such piezoelectric transducer were utilized. Additionally, the use oE two piezoelectric transducers allows for a higher power inpu~ into the print head for a given voltage and, consequently, for a higher maximum power input into the print head, since only a limited voltage differential may be placed across a piezoelectric transducer without break down of the transducer.
As is well known, E, p and L are temperature dependent and, as a con.sequence, the resonant Eeequ~ncy oE the print head varies with changes in temperature. The variation Af in Eo for a temperature chanc~e oE Aq', at or near room temperature, is given by AE = AfokAll/2~ where k is approximateLy ~ x 10-4/C Eor stainless steel.
Whell the dimensions a and h are smal:L as compared to L, the print head can be driven at a Erequency off resonance. ~ig. 5 illustrates the changes in the driving voltage applied to the transducers which are required in order to drive a single jet print head for a constant nominal filament length oE 16.5 x 10-3 . In general, the nominal filament length is a function of both the driving voltage and the driving frequency. At any given driving frequency the nominal filament length decreaes with increases in the driving voltage.
~L9776 From Fig. 5, it is clear that at resonance, 83 KHz, the print head requires a drive voltage of approximately 20 volts peak-to-peak. When driven by an oscillator at a frequency to either side oE the resonant frequency, the driving voltage must be increased substantially in order to maintain the filament length at 16.5 x 10-3 . On either side of the resonant frequency, the voltage required rises approximately linearly with frequency. There is, however, a maximum voltage which may be applied to the piezoelectric transducers and, so long as the maximum voltage is not exceeded, the transducers may be driven on the positive slope portion of the curve of Fig. 5, or the negative slope portion of the curve. Assuming that the resonant frequency remains constant, the driving frequency may be varied in synchronization with Eluctuations in speed of the print receiving mediurn upon which drops from the print head are to be deposit:ed, thereby compensating ~or SUCtl Eluctuations. In such an instance, the frequency oE the drive signal i9 monitored, however, and the volta~e oE the drive signal adjusted accordingly in order to compensate for the frequency shiet and thereby maintain the desired fluid filament length.
If desired, the additional piezoelectric transducer 44 may be utilized to monitor the Erequency oE the drive signal and amplitude of vibration of the print head. In Fig. 6, the voltage output on line 46 is plot~ed against the frequency of the driving signal for the maintenance of a MDF 002 P2 -16- ~2~7~6 single jet print head nominal fluid filament of a length equal to 16.5 x 10-3 , and a diameter of approximately 1 x 10-3 . Assuming no change in the resonant frequency o the print head or the jet, a fluid filament of a desired length can be maintained by monitoring the output voltage and frequency on line 46 and adjusting the level of the driving signal as needed to maintain the output voltage on line 46 at a reference voltage level specified by the curve of Fig. 6.
It will be appreciated that numerous variations may be made in the disclosed print head within the scope of the present invention. For example, flanges 34 may be deleted. Another arrangement, such as support screws may be provided for attaching the print head body to appropriate support structure, as long as the point or points of attachment lie substantially in the nodal plane intermecliate the ends oE print head body 10.
Reference is made to Fig. 7 which illustrates a circuit which provides a means for supplying an electrical driving signal. The output oE a flxecl frequency osciLlator 48 is supplied to transducers 36 and 38 via a voltage controlled a~tenuator circuit 50, a power amplifier 52 and a step-up transformer 54. The output from transducer 44 on line 4fi is used to control the amount of attenuation provided by circuit 50. The signal on line 46 is amplified by amplifier 56, converted to a d.c. signal by converter 58, and then compared to a selected reference signal by summing circuit 60 to MDF 002 P2 ~ 2~76 produce a signal on line 62 which controls the attenuation provided by circuit 50. By this feedback arrangement, the amplitude of the driving signal on line 42 and the amplitude of the mechanical vibration of the print head are precisely controlled.
Fig. 8 is a side view illustrating a second embodiment of the present invention, with elements corresponding to the print head of Fig. 1 being labeled with identical reference numerals. In this embodiment the transducers 36 and 38 are oriented on the print head body such that a positive driving signal on line 42 causes one of the transducers to elongate and the other transducer to contract, while a negative driving signal has the opposite effect.
As a consequence, as an a.c. driving signal is supplied to line 42, the print head is caused to vibrate in its first flexure mode. This vibrational mode i5 iLlustrated in E'i~. ~ by medial lines 6~
which, alttlough greatly exaggerated in Elexure Eor purpose~s oE clarity, indicate the extent of movement of the center oE the print head body 1~. It should be noted that lines 64 cross at points which are approximately .23L inward from each end oE the print head body, thus indicating nodal points. Mounting hoLes 66 are drilled into body 14 at the nodal points and a second corresponding pair of mounting holes are drilled into the opposite side of the print head body. By providing mounting pins which extend into holes 66, pivot supports are provided which do not interfere with flexure of the print head.
~IDF 002 P2 -18- 12~
This flexure mode may be excited by driving the transducers at a frequency Fo = ~Ca/L2, where ~is approximately 1.76.
This is a simplification of the resonant frequency equation Fo = 9~CK/8L2, where K is the radius of gyration, which for the print head illus-trated equals a/2.
It will be further appreciated that the present invention is not limited to the precise method and form of apparatus disclosed, and that changes may be made in either without departing from the scope of the invention.
Background of the Invention The present invention relates to a fluid jet print head and, more particularly, to a print head and method for generating at least one stream of drops in which construction and operation of the print head ar~
facilitated.
Jet drop printers and coating devices operate by generating streams of small drops of ink or coating fluid and controlling the deposit of the drops on a print receiving medium. Typically, the drops are electrically charged and then deflected by an electrical field. The drops are formed from fluid filaments which emerge from small orifices. The orifices communicate with a fluid reservoir in which fluid is maintained under pressure.
Each El~1id Eilament tends to break apart at its tip to form a stream of drops. In order to deELect drops acc~lrateLy by means of an el.ectrical field and produce selective cleposition of the drops on the print receiving nlc~diuln, iL i~. r1ece~sary lor th~ drop~q to be sub.qtantial1y uniEorm in size and ln interdroE~ spacin~ within each stream. 'L'he brealc up of the fiLaments into streams of drops is Eacilitated by mechar1ical vibration of some portion or all of the print head structure in a process termed "stimulation".
One prior art stimulation technique, as shown in tl.S. patel1t No. 3,739,393, is~ued June 12, 1973, to Lyon et al, is to provide the fluid oriEices in a relatively thin, flexible wall of the fluid reservoir and to stimulate this wall, known as an "orifice plate", by causing a series of bending waves to travel along the MDF 002 P2 -2- ~2~6 plate. This technique results in substantially uniform drop size and spacing but the timing of break up of the fluid filaments varies along the length of the orifice plate.
Another approach is to vibrate the entire print head, including the ink manifold structure and the orifice plate structure, together. This is shown in U.S. patent No. 3,586,907, issued June 22, 1971, to Beam et al. Such an arrangement will necessarily fatigue the print head mounting structure, since the mounting structure experiences the same vibrations which are applied to the manifold and the orifice plate. Further, the amplitude and phase of the vibratory motion are difficult to control at the frequencies commonly used for jet drop printer operation.
A further approach to filament stimulation is disclosed in U.S. patent No. 4,095,232, issued June 13, 197~, to Cha. U.sing the tecllllique discl.osed in this patent, stimulators mounted in the upper portion oE a Eluid reservoir generate pressure waves which are transmitted downward through the Eluid. ~ach stimulator ir)cludes a pair oE piezoelectric crystal.s which vibrate in pllase and which are mounted on opposite sides oE a mountillg plate which is coincident with a nodal plane. A
reaction mass is positioned at the end oE each stimulator opposite the stimulation member which is coupled to the fluid. The reaction mass ensures that the nodal plane is properly positioned.
In British patent specification 1~22388, a print head is disclosed in which a piezoelectric crystal forms one wall of a single-jet ink jet print head. When a drop MDF 002 P2 -3- ~2~9~
is to be emitted from the orifice, the piezoelectric transducer is electrically actuated, causing it to distort and thereby forcing a drop from the orifice.
In British patent specification 1293980, published October 25, 1972, and U.S. patent No. 4,19~,643, issued April 15, 1980, to Cha et al, print heads are disclosed in which a pair of piezoelectric crystals are bonded to opposite sides of a support plate. A print head manifold structure is bonded to one of the piezoelectric crystals and a counterbalance is bonded to the other of the crystals. The weight of the counterbalance is selected so as to offset the weight of the print head manifold. By this balanced arrangement, the support plate is placed in a nodal plane when tlle two piezoelectric transducers are energized in svnchronism. It will be appreciated, however, that the construction Oe such a print head is relatively complicated and, Eurther, that it is diEEiclllt to design such a print heacl to be resonant at a desire.l Erequellcy. r~'he print head m~lst be tuned subsecluell~ to construction, therecore, such that the resonant Erequency oE t~e print llead equals che desired operating Erequency.
Flnally, in U.S. pa~ell~ No. 3,972,47~, issued ~ugust 3, 1976, to i~eur, an ink drop writing system is showll in whicll a vibratin-3 nozzle is used to produce a stream of drops. The length oE the nozzle is selected so that its mechanical resonallt frequency is much higher than the frequency at which it is driven. The nozzle, configured as a tube, is surrounded by a piezoelectric ring which, when electrically driven, provides radial contraction and expansion of the tube.
MDF 002 P2 -4~ 977~
There is a need for an improved fluid jet print head in which uniform in-phase stimulation may be provided for a plurality of jet drop streams, in which mounting oE
the print head is facilitated, and in which construction and design of the print head are simplified.
Summary_of the Invention A fluid jet print head for generatinq at least one stream of drops comprises an elongated print head body, the length of the body between first and second ends thereof being substantially greater than its other dimensions. The body defines a fluid receiving reservoir in its first end and at least one orifice communicating ~ith the fluid receiving reservoir. Fluid is supplied to the reservoir under pressure by appropriate means such that it emeryes from the reservoir to Eorm a fluid stream. ~ transducer means is mountec~ on the exterior of the body and extends a substantial distance a:Long the body in the direction of elongation Erom adjacent the support means toward both the Eir~st ancl second ends oE the body.
Ihe tran-;~lucer means is responsive to an electrical drivincJ sigrla:L Eor changillg dimcnsion in the direction of elongatiorl oE the body, thereby causing mechanical vibrcltion oE the body and break up oE the f:luid stream into a stream oE drops.
rile transducer means compri.ses a pair oE
piezoelectric transducers bonded to opposite sides of the hody and extending in the direction of elongation from points adjacent the first end to points adjacent the second end of the body. The piezoelectric transducers provide alternate lengthening and contraction of the elongated print head body in the direction of elongation of the body.
l9~;
The transducer means further comprises means for electrically connecting the pair of transducers in parallel, whereby the transducers operate in phase so as to produce vibration which is in a direction substantially parallel to the direction of elongation of the elongated print head body. A support means for the print head engages the print head body intermediate and substantially equidistant from its first and second ends.
Alternatively, the transducer means may comprise means for electrically connecting the transducers so that they operate out of phase, thus producing flexure waves.
The support means for the print head engages the print head body a distance from each end of the body approximately equal to .23 of the overall length of the body.
F'or vibration parallel to the direction of elongation, the support means may comprise a pair of mountinq Elanges, each inteqrally formed with the print head body, and being relatively thin. The flanges extend Erom the elongated print heacl hocly on opposite si.des thereoE ancl are substantially equidis~ant from the first ancl secolld encls o~ the bocly such that they support the bocly alonc3 a noclaL plane. Alternatively, the support means may compri.se a pair of support screws which engage the body at opposite sides thereof at points substantially ecTuidistant from the first and second ends of the print head body.
The print head body includes means defining a slot in the first end thereof and orifice plate means, attached to the means defining a slot, and forming the fluid receiving reservoir therewith. The orifice plate ~IDF 002 P2 -6- ~2~
means may define a plurality of orifices for production of a plurality of drop streams. The print head body may further define a Eluid supply opening and a fluid outlet opening communicating with the slot. The fluid jet print head may further lnclude fluid conduit lines connected to the fluid supply opening and the fluid outlet opening.
The fluid conduit lines are formed of a material having a substantially different vibrational impedance than the print head body, whereby the conduit lines do not provide a substantial power loss. The fluid conduit llnes may, for example, be made of a poLymer material.
The fluid jet print head may further include means for applying an electrical driving signal of a frequency substantially equal to fo = C/2L, where L is the dimension of the body in the direction of elongation, and C is the speed of sound through the body. In this case the fluid ~et print head is driven at a Erequency approximating its mechanical resonant: Erequency.
r~or Elexure wave vibration, the tran.sducers are driven at a Erecl-lency Fo ~ /L2~ wh(?re a is the transverse thickness oE the print head body and ~ -1.7.
In this case, two nodal mounting axes are established a distance equal to approximately .23 oE the length oE the print heacl body/ centerecl betwe~en the transducers.
The mettlod Eor stimulating the break up of a fluid stream emanatLng from at least one orifice communicating with the fluid reservoir in a fluicl jet print head includes the steps oE:
(a) providing an elongated print head which defines the reservoir and the orifice at one end thereof;
(b) applying fluid under pressure to the reservoir so as to produce fluid flow through the orifice;
(c) supporting the print head at points in a plane substantially equidistant from the ends of the elongated print head and normal to the direction of elongation of the print head; and (d) alternately elongating and contracting the print head substantially at the resonant frequency of the print head, whereby the print head is supported in a nodal plane and the stream is eEfectively stimulated to break up into drops.
The resonant frequency of the print head may be substantially equal to the resonant frequency o~ the fluid stream. The print head may be elongated and contracted by means of piezoelectric trans-lucers bonded to its exterior.
The stream may also be stimulated by operatincJ the transducers ouk of phase, thereby causing ~lexure of the print head. In this stimuLation mode, the print head is mounted at points which are a distance Erom each end which are approximately equal to ~23 times the length of the print head.
Accordingly, it is an object oE the present invention to provide a fluid jet print head for generating one or more streams of drops in which the print head includes an elongated body which is driven to elongate and contract in the direction of MDF 002 P2 -8- ~9~7~
elongation of the body; to provide such a print head and method in which the print head is driven by means of thin piezoelectric transducers bonded to the print head exterior; and to provide such a print head in which support for the print head is provided in a nodal plane.
Other objects and advantages of the invention will be apparent from the following description, the accompanying drawings and the appended claims.
Brief Description of the Drawings .
Fig. 1 is an exploded view, illustrating a first embodiment of the fluid jet print head of the present invention;
Fig. 2 is a plan view oE the print head oE
Fig. 1, with the orifice plate removed;
Fig. 3 is a side view oE the print head oE
Fig. l with the electrical drive circuitry illustrated;
Fig. 4 is an enlarc3ecl partial sectional view, taken c~enerally along line 4-4 in Fig. 2;
Fic~. 5 is a graph, use~ul in explaining the operation oE the print hea~3 oE the present invention;
Flig~ 6 is a graph, useful in e~plaining operation oE the print head of the present invention.
Fig. 7 is a schematic diagram illustrating driving circuitry for the fluid print heacl; and F`ig. ~ is a side view oE a second embodiment of the fluid jet print head of the present invention.
Detailed Description of the Preferred Embodiments The present invention relates to a fluid jet print head oE the type which may be used for ink jet printing, coating, textile dyeing, and other purposes. As is known, such devices typicall~
operate by electrically charging the drops in one or more jet drop streams and, thereafter, deflecting the trajectories of some of the drops by means of electrical fields. In order to produce the stream or streams of drops, fluid is typically applied to a fluid reservoir under pressure such that it then flows through one or more orifices or nozzles which communicate with the reservoir. The fluid emerges from the orifices as fluid filaments which, i~ left undisturbed, would brealc up somewhat irregularly into drops of varying size and spacing. It is not possible to charge and deflect such nonuniform drops accurately and, as a consequellce, jet drop devices have typically applied mechanical stimulation in some Eashion to the f]uid Eilaments so as to cause break up oE the filame~nts into clrops of generally uniEorm size allcl spacin~ at a deqired clrop break up frequency.
A first ernbocliment of the print head of the present invention is shown in Figs. 1-4. ~rhe print head generally includes an elongated print head body lO, the Length of which, L, is substantially greater than its other dimensions a and b. The body lO
includes an orifice plate 12 and a block of material 14. The body lO defines a fluid receiving re,ervoir 16 in its first end, and at least one and preferably ~DF 002 P2 -10-a number oE orifices 18 which are arranged in a row across orifice plate 12. The orifice plate 12 is bonded to block 14 of material, such as stainless steel by means oE a suitable adhesive. Block 14 defines a slot 20 which, in conjunction with orifice plate 12 defines the reservoir 16. The block 14 further defines a fluid supply opening 22 and a fluid outlet opening 24, both of which communicate with the slot 20.
The print head further includes means for supplying fluid to the reservoir 16 under pressure such that fluid emerges from the ori~ices 1~ as 1uid Eilaments which then break up into streams of drops. This includes a pump 26 which receives fluid from a tank 28 and delivers it, via fluid conduit line 30, to the reservoir 16. A conduit 32 is connected to fluid outlet 2~ such that fluid may be removecl from the re~qervoir L6 at shut down of the print head or during cross-Elushill~ oE the reservoir L6. As wlll become apparent, the end oE the print head to which conduits 30 and 32 are attached, as well as the opposite encl of the print head, i;
subjected to mechanical vibrations which cause the fluid filalnents to break up into streams of drops of uniform si~e and spacing. The conduits 30 and 32 are selected from among a number of materials, such as a polymeric material, which have a vibrational impedance substantially different from that oE the stainless steel block 14. As a consequence, power loss through the conduits 30 and 32 and the resulting damping of the vibrations are minimized.
r~lDF 002 P2 ~ 77~
The print head further includes support means, such as mounting flanges 34. Flanges 34 are relatively thin and are integrally formed with the block 14. The flanges 34 extend from opposite sides of the elongated print head body 10 and are substantially equidistant from the first and second ends of the body. As a result, the flanges may be used to support the body 10 in a nodal plane. The flanges 34 are therefore not subjected to substantial vibration.
The print head further comprises a transducer means, including thin piezoelectric transducers 36 and 38. The transducers are bonded to the exterior oE the body of block 14 and extend a substantial distance along the body in the direction of elongation thereof, from ad~aeent the support means toward both the first and seconcl ends of the body. The transdueers 36 and 3~ respond to an electrical drivlncJ sicJnal, provided by power supply ~0 on lin~ ~2, by eharlcJiny dimension, thereby causing meehallieal vibration oE the body and break up oE the Elllid streams into streams of drops.
'I'ht~ piezoeleetric transclueers 36 and 3~
have electrically eonduetive eoatings on their outer ~urfaces, that is the sur~aces away frorn the print head block 1~, whieh define a first eleetrode for each such transducer. The metallie print head bloek 14 typieally grounded, provides the seeond electrode for eaeh of the transdueers. The piezoeleetric transducers are seleeted such that when driven by an a.e. drive signal, they alternately expand and ~IDF 002 P2 -12~
contract in the direction of elongation oE the print head. As may be seen in Fig. 3, transducers 36 and 38 are electrically connected in parallel. The transducers are oriented such that a driving signal on line 42 causes them to elongate and contract in unison. Since the transducers 36 and 3~ are bonded to the block 14, they cause the block to elongate and contract, as well.
If desired, an additional piezoelectric transducer 44 may be bonded to one of the narrower sides o e the print head to provide an electrical output potential on line 46 which fluctuates in correspondence with the elongation and contraction of the print head block 14. The amp]itude of the signal on line 46 is proportional to the amplitude oE the mechanical vibration of the block 14.
rrhe mechanism by which the Eirst embodiment Oe the print head oE the present invention functions may be deseribc-.~d as Eollows. rl'hc elongated print heacl bocly is som~what analogous to an ordinary hellcal speing. If such a spring i5 COmpreS5ed alld then quickly released, it will oscillate about its center at a frequency eO, callec~ its Eundamental longitudinal resonant Erequency. In this eondition, both ends of the spring move toward and away from the center of the spring, while the center remains at rest. Therefore, if one fixes the center of the spring and repeats the above described operation, the spring will oscillate in the same manner at the Erequency Fo.
MDF 002 P2 -13- ~Z~97~6 The steel block 14 which forms a part of the print head body can be considered to be a very stiff spring. If properly mechanically stimulated, it may therefore be held at its center, as by flanges 34, while both ends of the block 14 alternately move toward and away from the center.
Since the center of the block lies in a nodal plane, the flanges 34 are not subjected to substantial vibration and the support for the print head does not interfere with its operation. As the end of the print head body 10 which defines the fluid receiving reservoir 16 is vibrated, the vibrations are transmitted to the fluid filaments which emerge frorn the orifices 16, thus ca~lsing substantially simultaneous uniform drop break up. Note that the reservoir 16 is small in relation to the overall size oE the block 14 and is centered in the end of the block. As a consequence, the reservoir 16 does not interE~re si~niEicantly with the vibration of the bLock ]4, nor a~Eect the resonant ~requency of the print llead substantially.
rt'he resonant frequency of the block 14 can ~enerally be said to be given by ~0 = C/2L =VE/P/2L
where C is the speed of sound through the print head block 14 material, L is the length of the print head body in the direction of elongation, E is the modulus of elasticity of the material forming block 14 and p is the density of the material forming the block 14. Preferably the print head is designed to operate at or near its resonant frequency, and this ~DF 002 P2 -14~ ~2~9~7~
frequency, in turn, is selected within an appropriate fluid jet stimulation frequency range, e.g., 50KH~ to ]OOKH~.
By providing a pair of piezoelectric transducers 36 and 38 on opposite sides of the block 14, the block 14 is elongated and contracted without the flexure oscillations which would otherwise result if only one such piezoelectric transducer were utilized. Additionally, the use oE two piezoelectric transducers allows for a higher power inpu~ into the print head for a given voltage and, consequently, for a higher maximum power input into the print head, since only a limited voltage differential may be placed across a piezoelectric transducer without break down of the transducer.
As is well known, E, p and L are temperature dependent and, as a con.sequence, the resonant Eeequ~ncy oE the print head varies with changes in temperature. The variation Af in Eo for a temperature chanc~e oE Aq', at or near room temperature, is given by AE = AfokAll/2~ where k is approximateLy ~ x 10-4/C Eor stainless steel.
Whell the dimensions a and h are smal:L as compared to L, the print head can be driven at a Erequency off resonance. ~ig. 5 illustrates the changes in the driving voltage applied to the transducers which are required in order to drive a single jet print head for a constant nominal filament length oE 16.5 x 10-3 . In general, the nominal filament length is a function of both the driving voltage and the driving frequency. At any given driving frequency the nominal filament length decreaes with increases in the driving voltage.
~L9776 From Fig. 5, it is clear that at resonance, 83 KHz, the print head requires a drive voltage of approximately 20 volts peak-to-peak. When driven by an oscillator at a frequency to either side oE the resonant frequency, the driving voltage must be increased substantially in order to maintain the filament length at 16.5 x 10-3 . On either side of the resonant frequency, the voltage required rises approximately linearly with frequency. There is, however, a maximum voltage which may be applied to the piezoelectric transducers and, so long as the maximum voltage is not exceeded, the transducers may be driven on the positive slope portion of the curve of Fig. 5, or the negative slope portion of the curve. Assuming that the resonant frequency remains constant, the driving frequency may be varied in synchronization with Eluctuations in speed of the print receiving mediurn upon which drops from the print head are to be deposit:ed, thereby compensating ~or SUCtl Eluctuations. In such an instance, the frequency oE the drive signal i9 monitored, however, and the volta~e oE the drive signal adjusted accordingly in order to compensate for the frequency shiet and thereby maintain the desired fluid filament length.
If desired, the additional piezoelectric transducer 44 may be utilized to monitor the Erequency oE the drive signal and amplitude of vibration of the print head. In Fig. 6, the voltage output on line 46 is plot~ed against the frequency of the driving signal for the maintenance of a MDF 002 P2 -16- ~2~7~6 single jet print head nominal fluid filament of a length equal to 16.5 x 10-3 , and a diameter of approximately 1 x 10-3 . Assuming no change in the resonant frequency o the print head or the jet, a fluid filament of a desired length can be maintained by monitoring the output voltage and frequency on line 46 and adjusting the level of the driving signal as needed to maintain the output voltage on line 46 at a reference voltage level specified by the curve of Fig. 6.
It will be appreciated that numerous variations may be made in the disclosed print head within the scope of the present invention. For example, flanges 34 may be deleted. Another arrangement, such as support screws may be provided for attaching the print head body to appropriate support structure, as long as the point or points of attachment lie substantially in the nodal plane intermecliate the ends oE print head body 10.
Reference is made to Fig. 7 which illustrates a circuit which provides a means for supplying an electrical driving signal. The output oE a flxecl frequency osciLlator 48 is supplied to transducers 36 and 38 via a voltage controlled a~tenuator circuit 50, a power amplifier 52 and a step-up transformer 54. The output from transducer 44 on line 4fi is used to control the amount of attenuation provided by circuit 50. The signal on line 46 is amplified by amplifier 56, converted to a d.c. signal by converter 58, and then compared to a selected reference signal by summing circuit 60 to MDF 002 P2 ~ 2~76 produce a signal on line 62 which controls the attenuation provided by circuit 50. By this feedback arrangement, the amplitude of the driving signal on line 42 and the amplitude of the mechanical vibration of the print head are precisely controlled.
Fig. 8 is a side view illustrating a second embodiment of the present invention, with elements corresponding to the print head of Fig. 1 being labeled with identical reference numerals. In this embodiment the transducers 36 and 38 are oriented on the print head body such that a positive driving signal on line 42 causes one of the transducers to elongate and the other transducer to contract, while a negative driving signal has the opposite effect.
As a consequence, as an a.c. driving signal is supplied to line 42, the print head is caused to vibrate in its first flexure mode. This vibrational mode i5 iLlustrated in E'i~. ~ by medial lines 6~
which, alttlough greatly exaggerated in Elexure Eor purpose~s oE clarity, indicate the extent of movement of the center oE the print head body 1~. It should be noted that lines 64 cross at points which are approximately .23L inward from each end oE the print head body, thus indicating nodal points. Mounting hoLes 66 are drilled into body 14 at the nodal points and a second corresponding pair of mounting holes are drilled into the opposite side of the print head body. By providing mounting pins which extend into holes 66, pivot supports are provided which do not interfere with flexure of the print head.
~IDF 002 P2 -18- 12~
This flexure mode may be excited by driving the transducers at a frequency Fo = ~Ca/L2, where ~is approximately 1.76.
This is a simplification of the resonant frequency equation Fo = 9~CK/8L2, where K is the radius of gyration, which for the print head illus-trated equals a/2.
It will be further appreciated that the present invention is not limited to the precise method and form of apparatus disclosed, and that changes may be made in either without departing from the scope of the invention.
Claims (19)
1. Fluid jet printing apparatus, comprising:
an elongated print head body, the length of said body between first and second ends thereof being substantially greater than its other dimensions, said body defining a fluid receiving reservoir in said first end thereof and a planar arrangement of orifices, communicating with said fluid receiving reservoir, means for supplying fluid to said reservoir under pressure such that fluid emerges from said orifices to form a plurality of parallel fluid streams, support means for engaging said print head body intermediate said first and second ends, a pair of parallel transducers mounted on exterior opposite surfaces of said body and extending a substantial distances along said body in the direction of elongation thereof, and driving means for providing said transducers with an electrical driving signal of predetermined frequency productive of resonant vibration in said body;
said transducers being responsive to said driving signal by changing dimension in the direction of elongation of said body thereby causing resonant mechanical vibration of said body at said frequency and resultant stimulation of said streams.
an elongated print head body, the length of said body between first and second ends thereof being substantially greater than its other dimensions, said body defining a fluid receiving reservoir in said first end thereof and a planar arrangement of orifices, communicating with said fluid receiving reservoir, means for supplying fluid to said reservoir under pressure such that fluid emerges from said orifices to form a plurality of parallel fluid streams, support means for engaging said print head body intermediate said first and second ends, a pair of parallel transducers mounted on exterior opposite surfaces of said body and extending a substantial distances along said body in the direction of elongation thereof, and driving means for providing said transducers with an electrical driving signal of predetermined frequency productive of resonant vibration in said body;
said transducers being responsive to said driving signal by changing dimension in the direction of elongation of said body thereby causing resonant mechanical vibration of said body at said frequency and resultant stimulation of said streams.
2. Apparatus according to claim 1 wherein said transducers are piezoelectric transducers.
3. Apparatus according to claim 2 wherein said orifices are located in the surface of said print head body at said first end so as to project said streams in a direction parallel to said direction of elongation.
4. Apparatus according to claim 3 and further comprising means for electrically connecting said pair of piezoelectric transducers in parallel.
5. Apparatus according to claim 4 in which said piezoelectric transducers are connected to elongate and contract in phase.
6. Apparatus according to claim 5 in which said support means engages said print head body substan-tially intermediate and equidistant from said first and second ends thereof.
7. Apparatus according to claim 4 in which said piezoelectric transducers are connected to elongate and contract out of phase, thereby producing flexure of said print head body.
8. Apparatus according to claim 7 in which said support means pivotally engages said print head body at flexure nodes.
9. Apparatus according to claim 1 in which said support means comprises a pair of mounting flanges, each integrally formed with said print head body, and being relatively thin, said flanges extending from said elongated print head body on opposite sides thereof and substantially equidistant from said first and second ends of said body such that said flanges support said body along a nodal plane.
10. Apparatus according to claim 1 in which said support means comprises a pair of support screws which engage said body at opposite sides thereof at points substantially equidistant from said first and second ends of said print head body.
11. Apparatus according to claim 1 in which said print head body includes means defining a slot in the first end thereof, and orifice plate means, attached to said means defining a slot, and forming said fluid receiving reservoir therewith.
12. Apparatus according to claim 11 in which said print head further defines a fluid outlet opening communicating with said slot.
13. Apparatus according to claim 12 further comprising fluid conduit lines connected to said fluid supply opening and said fluid outlet opening, said fluid conduit lines being formed of a material having a substantially different vibrational impedance than said print head body, whereby said conduit lines do not provide a substantial power loss.
14. Apparatus according to claim 13 in which said fluid conduit lines are made of a polymer material.
15. Apparatus according to claim 1, further comprising monitor transducer means, mounted on the exterior of said body and providing an electrical monitor signal in response to dimensional changes of said body.
16. Apparatus according to claim 5 further comprising means for applying an electrical driving signal of a frequency substantially equal to fo, where fo = C/2L, L is the dimension of said body in the direction of elongation, and C is the speed of sound through said body, whereby said fluid jet print head may be driven at a frequency approximately its mechanical resonant frequency.
17. Apparatus according to claim 1 further comprising monitor transducer means, mounted on the exterior of said body and providing an electrical monitor signal in response to dimensional changes of said body, and means, responsive to said monitor transducer means, for applying an electrical driving signal to said transducers of an amplitude dependent upon said electrical monitor signal.
18. Apparatus according to claim 7 further comprising means for applying an electrical driving signal of a frequency substantially equal to F
where Fo = 9 CK/8L2, L is the dimension of said body in the direc-tion of elongation, C is the speed of sound through said body, and K
is the radius of gyration of said body.
where Fo = 9 CK/8L2, L is the dimension of said body in the direc-tion of elongation, C is the speed of sound through said body, and K
is the radius of gyration of said body.
19. A method of fluid jet stimulation comprising the steps of:
applying fluid to an elongated print head having a generally rectangular cross section and an orifice at a surface thereof;
said fluid being applied under pressure such that said fluid flows through said orifice to form a fluid jet, securing a pair of elongated transducers to opposite surfaces of said print head; said transducers being oriented parallel to the direction of elongation of said print head, and periodically elongating said transducers to produce resonant vibration of said print head and resulting stimulation of said jet.
applying fluid to an elongated print head having a generally rectangular cross section and an orifice at a surface thereof;
said fluid being applied under pressure such that said fluid flows through said orifice to form a fluid jet, securing a pair of elongated transducers to opposite surfaces of said print head; said transducers being oriented parallel to the direction of elongation of said print head, and periodically elongating said transducers to produce resonant vibration of said print head and resulting stimulation of said jet.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US39010582A | 1982-06-21 | 1982-06-21 | |
| US390,105 | 1982-06-21 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1219776A true CA1219776A (en) | 1987-03-31 |
Family
ID=23541082
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000425460A Expired CA1219776A (en) | 1982-06-21 | 1983-04-08 | Fluid jet print head |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0097413B1 (en) |
| JP (1) | JPS595071A (en) |
| CA (1) | CA1219776A (en) |
| DE (1) | DE3364155D1 (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4646104A (en) * | 1982-06-21 | 1987-02-24 | Eastman Kodak Company | Fluid jet print head |
| JPS62131779U (en) * | 1986-02-07 | 1987-08-20 | ||
| US6336708B1 (en) | 1992-09-18 | 2002-01-08 | Iris Graphics, Inc. | Ink jet nozzle |
| US5407136A (en) * | 1992-09-18 | 1995-04-18 | Iris Graphics, Inc. | Ink-jet nozzle |
| DE69406734T2 (en) * | 1993-08-17 | 1998-03-12 | Scitex Digital Printing Inc | Assembly arrangement for resonators |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| BE790064A (en) * | 1971-10-14 | 1973-02-01 | Mead Corp | DROP GENERATOR FOR RECORDING DEVICE. |
| US4095232A (en) * | 1977-07-18 | 1978-06-13 | The Mead Corporation | Apparatus for producing multiple uniform fluid filaments and drops |
| US4245227A (en) * | 1978-11-08 | 1981-01-13 | International Business Machines Corporation | Ink jet head having an outer wall of ink cavity of piezoelectric material |
| US4198643A (en) * | 1978-12-18 | 1980-04-15 | The Mead Corporation | Jet drop printer with elements balanced about support plate in nodal plane |
-
1983
- 1983-03-31 DE DE8383301874T patent/DE3364155D1/en not_active Expired
- 1983-03-31 EP EP19830301874 patent/EP0097413B1/en not_active Expired
- 1983-04-08 CA CA000425460A patent/CA1219776A/en not_active Expired
- 1983-06-11 JP JP10484083A patent/JPS595071A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS595071A (en) | 1984-01-11 |
| EP0097413B1 (en) | 1986-06-18 |
| EP0097413A1 (en) | 1984-01-04 |
| JPH038946B2 (en) | 1991-02-07 |
| DE3364155D1 (en) | 1986-07-24 |
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