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Sommaire du brevet 1175359 

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Disponibilité de l'Abrégé et des Revendications

L'apparition de différences dans le texte et l'image des Revendications et de l'Abrégé dépend du moment auquel le document est publié. Les textes des Revendications et de l'Abrégé sont affichés :

  • lorsque la demande peut être examinée par le public;
  • lorsque le brevet est émis (délivrance).
(12) Brevet: (11) CA 1175359
(21) Numéro de la demande: 1175359
(54) Titre français: APPAREIL D'IMPRESSION A GICLEURS D'ENCRE EN ARROI
(54) Titre anglais: ARRAYED INK JET APPARATUS
Statut: Durée expirée - après l'octroi
Données bibliographiques
(51) Classification internationale des brevets (CIB):
  • B41J 2/145 (2006.01)
  • B41J 2/055 (2006.01)
  • B41J 2/14 (2006.01)
(72) Inventeurs :
  • MARTNER, JOHN G. (Etats-Unis d'Amérique)
(73) Titulaires :
  • EXXON RESEARCH AND ENGINEERING COMPANY
(71) Demandeurs :
  • EXXON RESEARCH AND ENGINEERING COMPANY (Etats-Unis d'Amérique)
(74) Agent: BORDEN LADNER GERVAIS LLP
(74) Co-agent:
(45) Délivré: 1984-10-02
(22) Date de dépôt: 1981-11-19
Licence disponible: S.O.
Cédé au domaine public: S.O.
(25) Langue des documents déposés: Anglais

Traité de coopération en matière de brevets (PCT): Non

(30) Données de priorité de la demande:
Numéro de la demande Pays / territoire Date
229,992 (Etats-Unis d'Amérique) 1981-01-30

Abrégés

Abrégé anglais


ABSTRACT OF THE DISCLOSURE
An elongated acoustic waveguide 20 couples a trans-
ducer 18 to an ink jet chamber 14 including an outlet
orifice 16 through which droplets of ink are ejected. In
one embodiment, the waveguide 20 is directly coupled to
ink within the chamber 14. Arrays are formed utilizing
such ink jet chambers 14 and waveguides 20.

Revendications

Note : Les revendications sont présentées dans la langue officielle dans laquelle elles ont été soumises.


THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A drop on demand ink jet apparatus comprising:
an ink jet chamber including an inlet port for receiving ink in
said chamber and an outlet orifice for ejecting ink droplets from said chamber;
an elongated single transducer remotely located from said
chamber; and
an elongated solid acoustic waveguide coupled between said ink
jet chamber and one end of said transducer for non-resonantly transmitting
individual acoustic pulses generated at said transducer to said chamber for
changing the volume of said chamber in response to the state of energization of
said transducer.
2. The ink jet apparatus of claim 1 wherein said chamber includes a
diaphragm coupled to said waveguide, said diaphragm contracting and expanding inresponse to said state of energization.
3. The ink jet apparatus of claim 1 wherein said pulses are
transmitted at said chamber in a direction having at least a component parallel
with the axis of the orifice.
4. The ink jet apparatus of claim 1 wherein said waveguide extends
in a direction having at least a component parallel with the axis of the
orifice.
5. The ink jet apparatus of claim 1 wherein said waveguide is
inserted substantially into said chamber.
6. The ink jet apparatus of claim 1 wherein at least a portion of
said waveguide includes a passageway for coupling ink from a reservoir to the
chamber.
7. The ink jet apparatus of claim 6 wherein said waveguide extends
through said reservoir, said inlet port being located in an intermediate portionalong the waveguide at said reservoir.
8. The ink jet apparatus of claim 7 wherein said inlet port
comprises a hole in said waveguide.

9. The ink jet apparatus of claim 6 wherein said passageway has a
lesser cross-section over said orifice than at said inlet port.
10. The ink jet apparatus of claim l wherein said acoustic waveguide
is elongated such that the overall length along the axis of propagation
substantially exceeds the dimension of said waveguide transverse to said axis.
11. The ink jet apparatus of claim 10 wherein said waveguide is
curved along the axis of elongation.
12. The ink jet apparatus of claim 1 wherein said waveguide abutts
the transducer.
13. A drop on demand ink jet array comprising:
a plurality of ink jet chambers, each of said chambers including
an inlet portion for receiving ink in said chamber and an outlet orifice for
ejecting ink droplets from said chamber;
a plurality of elongated transducers remotely located from said
chambers, respectively;
a plurality of solid elongated acoustic waveguides coupled
between said ink jet chambers and said transducers respectively for transmittingacoustic pulses generated at said transducers to said chambers for changing the
volume of said chambers in response to the state of energization of said
transducers, respectively.
14. The ink jet array of claim 13 wherein said waveguides are of
differing lengths along their axis of elongation.
15. The ink jet array of claim 14 wherein said waveguides converge
toward an array of said chambers.
16. The ink jet array of claim 15 wherein the maximum distance
between said array of chambers is substantially less than the maximum distance
between said transducers.
17. The ink jet array of claim 15 wherein all of said transducers
are located at one side of the axis of an orifice at one extremity of said array.
18. The ink jet array of claim 13 wherein each of said chambers
include a diaphragm coupled to said waveguide, said diaphragm contracting and
16

expanding in response to said state of energization.
19. The ink jet array of claim 18 wherein said diaphragm expands and
contracts in a direction having at least a component parallel with the axis of
its associated orifice.
20. The ink jet array of claim 18 wherein said waveguide extends in
a direction having at least a component in parallel with the direction of
expansion and contraction of said diaphragm.
21. The ink jet array of claim 20 wherein said diaphragm expands and
contracts in a direction having at least a component parallel with the axis of
the orifice.
22. The ink jet apparatus of claim 10 wherein said pulses are
transmitted at said chamber in a direction having at least a component parallel
with the axis of the orifice.
23. The ink jet apparatus of claim 10 wherein said waveguide extends
in a direction having at least a component parallel with the axis of the orifice.
24. The ink jet apparatus of claim 10 wherein at least a portion of
said waveguide includes a passageway for coupling ink from a reservoir to the
chamber.
25. The ink jet apparatus of claim 24 wherein said waveguide extends
through said reservoir, said inlet port being located in an intermediate portionalong waveguide at said reservoir.
26. The ink jet apparatus of claim 25 wherein said inlet port
comprises a hole in said waveguide.
27. The ink jet apparatus of claim 24 wherein said passageway has a
lower cross-section over said orifice than at said inlet port.
28. The ink jet array of claim 10 wherein each of said acoustic
waveguides is elongated such that the overall length along the axes of
propagation greatly exceeds the dimension of said waveguides transverse to said
axis.
29. The ink jet array of claim 10 wherein said plurality of
waveguides are removably coupled to said ink jet chambers.
17

30. The ink jet apparatus of claim 1, wherein said elongated
transducer is energizable for contracting along its axis of elongation, for
causing expansion of the volume of said chamber.
31. The ink jet apparatus of claim 1, wherein said elongated single
transducer is energizable by application of a field transverse to the direction
of expansion or contraction of said transducer.
18

Description

Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.


j35~
ARRAYED INK JET APPARATUS
1 BACKGROUND OF THE INVENTION
-
2 This invention relates to ink jets, more particularly,
3 to ink jets adapted to eject a droplet of ink from an ori-
4 fice for purposes of marking on a copy medium.
It is desirable in certain circumstances to provide
6 an array of ink jets for writing alpha-numeric characters.
7 For this purpose, it is frequently desirable to provide a
8 ; high density ink jet array. However, in many instances, the
9 stimulating element or transducers of such an array are
sufficiently bulkv so as to impose serious limitations on
11 the density in which ink jets may be arrayed. In this con-
12 nection, it will be appreciated that the transducers must
13 typically comprise a certain finite size so as to provide
14 the energy and displacements required to produce a change
in ink jet chamber volume which results in the ejection of
16 a droplet of ink from the orifice associated with the ink
17 chamber.
18 It will also be appreciated that efforts to create
19 a hiyh density ink jet array may produce undesirable cross
~ talk between the ink jets in the array. This is a result,
~1 at least at large part, of the relatively close spacing of
22 ink jets in the array.
23 When efforts are made to achieve a high densit~
24 array, the ink jet transducers become intimately associated
with the fluidic section of the ink jet, i.e., the ink
26 chambers and orifices. As a conse~uence, any failure in
27 the fluidic section of the device, which is far more common
28 than a failure of the transducer, necesitates the disposal
29 of the entire apparatus, i.e., both the fluidic section and
the transducer.
31 SUMMARY OF THE INVENTION
32 It is an object of this invention to provide a high
33 density ink jet array.
34 It is a further object of this invention to provide
an ink jet array to minimize cross talk between ink jets.

i359
-- 2 --
l It is a still further object of this invention to
2 provide an ink jet array which facilitates disposability
3 of the fluidic channel section of the ink jets indepen-
4 dently of the transducers of the ink jets.
It is a further objec~ of this invention to provide
6 a fluidic feeding system to the jets that minimize air
7 entrapment and cavitation sites.
8 It is a further object of this invention to provide
9 a waveguide array that is encapsulated in a suitable
material to prevent generation of flexural vibration that
11 can cause cross talk to neighboring fluidic feeding chan-
12 nels.
13 In accordance with these and other objects of the
14 invention, an ink jet apparatus comprises an ink jet
chamber including an inlet port for receiving ink in the
16 chamber and an outlet orifice for ejecting ink droplets
17 from the chamber. A transducer is remotely located from
18 the chamber and an elongated either solid or tubular acous-
l9 tic waveguide is coupled between the ink jet chamber and
the transducer. The acoustic waveguide transmits acoustic
21 pulses generated at the transducer to the chamber for
22 changing the volume of the chamber in response to the state
23 of energization~of the transducer.
~24 In accordance with this invention, acoustic pulses
are transmitted along the waveguide in the following manner.
26 When the transducer is energized, the ends thereof move in
27 an axial direction in an amount determined by the voltage
28 ~ applied to the transducer. If one end of said transducer
29 is affixed to a solid back piece, the other end will move
against the abutted end of the waveguide. The abutted end
31 of the waveguide will then be driven along in the same
32 direction by an amount corresponding to that of the end of
33 the transducer. If the driving pulse (voltage) is sharp,
34 e.g., the voltage takes a short time to reach its final
value, the end of the transducer will move fast; the end
36 of the waveguide will move accordingly fast, and only part
37 of said waveguide will be able to follow the fast motion.
,

~7~35~
1 The rest of the waveguide will stay at rest. The end of
2 the waveguide that was initially deformed will relax by
3 pushing and elastically deforming consecutive portions along
4 the waveguide. This successive displacement of the elastic
deformation ultimately reaches the distal end of the wave-
6 guide. The last portion thereof causes the fluid within
7 the chamber to be compressed and thus causes the ejection
8 of fluid droplets from the nozzle orifice. The physical
9 properties used in this invention are those of a true
wave traveling along the waveguide length and not those
11 of a push rod whereby when one end of the rod is moved,
12 the other end will move in unison.
13 In accordance with one important aspect of the inven-
14 tion, a plurality of such ink jets are utilized in an
array such that the spacing from center to center of trans-
16 ducers is substantially greater than the spacing from axis
17 to axis of the orifices. This relative spacing of trans-
18 ducers as compared with orifices is accomplished by con-
19 verging the acoustic waveguide toward the orifices.
In accordance with another important aspect of this
21 invention, all of the transducers are located at one side
22 of the axis of the orifice at one extremity of the array.
23 In accordance with another important aspect of the
24 invention, the waveguides are of differing lengths along the
axes of elongation.
26 In accordance with another important aspect of the
27 inventïon, the waveguides are tapered so that their dia-
28 meter at the distal ends are substantially smaller than
29 those at the transducer ends~ This tapering of the wave-
guides provides yet closer spacing between the waveguides,
31 thus further increasing the channel density.
32 In accordance with yet another important aspect of
33 the invention, the tapered ends of the waveguides are made
34 of tubular material to provide a fluid feed channel to thus
maintain the chambers filled with fluid.
36 In accordance with yet another important aspect of
37 the invention, the fluid feed channels are provided with an
- `

~7535~
orifice at the distal end having a cross-sectional area smaller
than the cross-sectional area of said fluid channel so as to
serve as a restrictor to control the flow of fluid passing there-
through.
In accordance with yet another important aspect of the
invention, the chambers of the ink jets may include a diaphragm
coupled to the waveguide such that the diaphragm contracts and
expands in response to the state of energization of the transducer
in a direction having at least a component parallel with the
axis of the orifice.
In accordance with yet still another important aspect
of the invention, each waveguide abutts the transducer and is
held thereon by means of a metal or ceramic ferrule that fits
both the transducer end and the waveguide end.
In accordance with another important aspect of the
invention, each acoustic waveguide is elongated such that the
overall length along the axis of elongation greatly exceeds the
dimension of the waveguide transverse to the axis.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a sectional view of an ink jet array
.
representing a preferred embodiment of the invention;
Fig. la is a sectional view taken along line la-la of
FigO l;
Fig. 2 is a partially enlarged view of the array shown
in Fig. l;
Fig. 2a is a sectional view taken along line 2a-2a of
Fig. 2;
~ ' ,r,~i_4_

~7535~
.
Fig. 2b is a sectional view taken along line 2b-2b of
Fig. 2;
Fig. 2c is a seational view taken along line 2c~2c of
Fig. 2;
Fig. 3 is a partially schematic diagram of yet another
embodiment of the invention;
Fig. 4 is a partially schematic diagram of still another
embodiment of the invention;
~ :.
: ~
~: :
:: ~
~:, ; : : : :
-;4a
:
.
'

~:~7S3~3
1 Fig~ 5 is a partially schematic diagram of still
2 another embodiment of the invention;
3 Fig. 6 is a sectional view of another embodiment
4 of the invention; and
Fig. 6a is a sectional view taken along line 6a-6a
6 of Fig. 6.
7 DETAILED DESCRIPTION OF PREFERRED EMB~DIMENT
-
8 ~eferring to Fig. 1, an ink jet array comprising a
9 plurality of jets 10 are arranged in a line so as to
asynchronously eject ink droplets 12 on demand. The jets
11 10 comprise chambers 14 having outlet orifices 16 from
12 which the droplets 12 are ejected. In accordance with this
13 invention, the chambers expand and contract in response to
14 the state of energization of transducers 18, which are
coupled to the chambers 14 by acoustic waveguides 20. In
16 further accordance with this invention, the waveguides 20
17 may actually be substantially inserted into said cham~er
18 by a distance d. as shown in Fig. 2.
19 In further accordance with this invention, the use
of the waveguides 20 which are coupled to the transducer
21 18 by a ceramic or metal ferrule 21 so as to permit the
22 jets~10 to be more closely spaced without imposing limi-
23 tations on the spacing o the transducers 18. More par-
2~4 ticularly, the centers of the chambers may be spaced by a
distance dc which is substantially less than the distance
26~ between the centers of the transducers dt~ This allows the
27 creation of a rather dense ink jet array regardless of the
28 ~configuration or size of the transducers 18.
2~9 In accordance with this invention, acoustic pulses
are transmitted along the waveguide 20 in the following
31 manner. When the transducer 18 is energized, the ends
32 thereof move~in an axial direction, i.e., the direction
33 parallel with the axis of elongation of the waveguide 20,
34 in an amount determined by the voltage applied to the
transducer 18. Since one end of the transducer 18 is
36 affixed to a solid back piece, the other end will move
37 against the abutting end of the waveguide 20. The abutting
.

~L17535~
-- 6 --
l end of the waveguide 20 will then be driven in the same
2 direction by an amount corresponding to the end of the
3 transducer 18. If the driving pulse is sharp, e.g., the
4 voltage takes a short time to reach its final value, the
end of the transducer will move fast; the end o-f the wave-
6 guide will move fast in a similar manner, and only part of
7 the waveguide 20 will be able to follow the fast motion.
8 The rest of the waveguide will stay at rest. The end of
9 the waveguide that was initially deformed will relax by
pushing an elastically deforming consecutive portion along
ll the waveguides 20. This successive displacement of the
12 elastic deformation ultimately reaches the distal end of the
13 waveguide 20. The last portion thereof causes the fluid
14 within the chamber 14 to be compressed and thus causes the
ejection of fluid droplets from the orifice. The physical
16 properties used in this invention are those of a true
17 waveguide traveling along the waveguide length and not
18 those of a piston whereby one end of the rod is moved and
19 the other end will move in unison.
In accordance with one important aspect of this
21 invention, the chambers 14 are coupled to a passageway 24
22 in the waveguide 20 which is terminated at the distal end
23 22 by an opening 26. The opening 26 is of a reduced cross-
24 sectional area as compared with the cross-sectional area
of the waveguide a greater distance from the orifice 16
26 (i.e., the passageway tapers) so as to provide a restrictor
27 at the inlet to the chamber 14. Ink enters the passageway
28 24 in the waveguide 20 through an opening 28, as perhaps
29 best shown in Figs. 2, 2a and 2c. The remainder of the
waveguide 20 may be filled with a suitable material 30
31 such as a metal piece or epoxy encapsulant.
32 During the operation of the ink jet array as shown
33 in Figs. l and 2, the distal end 22 of the waveguide 20
34 expands and contracts the volume of the chamber 14 in a
direction 32 having at least a component parallel with the
36 axis of the orifice 16. It will, or course, be appreciated
~ 37 that the waveguides 20 necessarily extend in a direction
,:
.

~ ~ ~ ~c~
1 having at least component parallel with the direction of
2 the expansion and contraction of the ends 22 of the wave-
3 guides 20.
4 It will be appreciated that the waveguides 20 as
shown in Fig. 1 are elongated. As utilized herein, the
6 waveguides 20 are considered elongated as long as the over-
7 all length along the axis of acoustic propagation greatly
8 exceeds the dimension of the waveguide transverse to the
9 axis, e.g., more than lO times greater.
As shown in Fig. 1, the waveguides 20 actually pene-
11 trate into the chambers 14. The position of the waveguides
12 20 in the chambers 14 may be preserved by maintaining a
13 close tolerance between the external dimension of the
14 waveguides 20 and the walls of the chamber 14 as formed in
a block 34. The block 34 may comprise a variety of mater-
16 ials including plastics, metals and/or ceramics. Ia A 17 Referring again to Fig. 1 in combination with Fig. ~,
18 it will be appreciated that the transducers 18 are potted
19 within a potting material 36 which may comprise elastomers
or foams. The waveguides 20 are also encapsulated or
21 potted within a material 38 as shown in Figs. 1 and 2. As
22 also shown in Fig. 2b, each waveguide 20 may be surrounded
23 by a sleeve 40, which assists in attenuating fluxural vi-
24 brations or resonances in the waveguide 20. In the alter-
native, sleeve 40 may be eliminated and the potting material
26 38 may be relied upon to attenuate resonances. A suitable
~7 potking material 38 includes elastomers, polyethylene or
28 polystyrene. The potting material 38 is separated from the
29 chamber block 34 by a gasket 41 which may comprise an
elastomer.
31 It will, or course, be appreciated that the trans-
32 ducers 18 must be energized in order to transmit an acoustic
33 pulse along the waveguides 20. Although no leads have been
34 shown as coupled to the transducers 18, it will be appre-
ciated that such leads will be provided for energization of
36 the transducers 18.

~L17S35~
-- 8 --
l By referring now to Figs. 1 and 2, it will be ap-
2 preciated that ink flows through the inlet ports 28 in
3 each of the waveguides 20 from a chamber 42 which communi-
4 cates through a channel 44 to a pump 46. The pump 46
supplies ink under the appropriate regulated pressure
6 from a supply 48 to the chamber 42. The pressure regula-
7 tion afforded by the pump 46 is important, particularly
8 in a typewriter environment, since considerable liquid
9 sloshing and accompanying chanSes in liquid pressure within
the chamber 42 and a passageway 44 may occur. As shown in
11 Fig. 1, the end of the ink jet array is capped by a member
12 50 which covers foot members 52 at the ends of the trans-
13 ducers 22 as well as the end of the pump 46.
14 As shown in Fig. 1, some of the waveguides 24 in-
dividually extend in a substantially straight li~e to the
16 respective chambers 14. Others may be bent or curved
~17 toward the chambers 14. As shown in Fig. 3, a somewhat
18 different transducer construction is utilized. More par-
~19 ticularly, an integral transducer 118 having a plurality of
legs 118(a-f) coupled to, for example, five jets 11~ of
21 the type shown in Fig. 1 through waveguides 120. Here
22 again, the configuration of the transducer block 118 is
23 immaterial so far as the density of the array of inX jets
24 is concerned~ Moreover, the disposition of the array of
ink jets 110 may be changed vis-a-vis the transducer block
26 118. As shown, all of the transducers 118(a-f) are located
27 at one side (shown as below) the axis x through the orifice
28 of the jet 110 located at one extremity (shown as the upper
29 extremity) of the array. As shown in Fig. 3 and in Fig. l
;30 the ink jet arrays are well suited for use in a printer
31 application requiring last character visibility because of
32 the skewing of the transducers to one side of the array of
33 jets 10. Referring now to Fig. 4, a plurality of trans-
34 ducers 218 and jets 210 are mounted on a two-tiered head
200. Once again, the jets 210 are very closely spaced so as
36 to achieve a dense array while the transducers 218 are
37 more substantially spaced. As a result, the waveguides

53S~
g
1 220 fan in or converge from the transducers 218 to the
2 jets 210. Fig. 5 shows an arrangement whereby two or more
3 heads 200 shown in Flg. 4 are sandwiched together to thus
4 form heads that have multiple rows of jets 210 with the
purpose of multiplying the writing capability of the
6 heads and thereby increasing the resolution of the char-
7 acters generated.
8 As clearly shown in Figs. 1, 3 and 4, the overall
9 lengths of the waveguides vary. This allows the distance
between the transducers to be maximized so as to minimize
11 cross talk between transducers as well as between wave-
12 guides.
13 Referring now to Figs. 6 and 6a, a somewhat dif-
14 ferent embodiment is shown wherein the acoustic waveguides
20 are coupled to the chambers 14 in a somewhat different
16 manner. In particular, the ends of the chambers 14 remote
17 from the orifices 16 are terminated by a diaphragm 60
18 including protrusions 62 which abut the waveguides 20.
19 Ink is capable of flowing into the chambers 14 through
~20 orifices 65 shown in Fig. 6a adjacent a restrictor plate
21 64. The openings 65 communicate with a reservoir 66 in
22 the manner disclosed in the aforesaid application. For
23 this purpose, the block 34 includes lands 68 which form the
24 restrictor openings 65 to the chamber 14 in combination with
the restrictor plate 64.
26 In operation, the pulse from a transducer travels
27 along each of the waveguides 20 in the embodiment shown in
28 Fig.~6 until such time as it reaches a projection 62 on the
29 diaphragm 60. This deforms the diaphragm 60 into and out
of the chamber 14 associated with that particular waveguide
31 20 so as to change the volume of that chamber and expell
32 droplets of ink 12 from the orifices 16. It will, there-
33 fore, be appreciated that the diaphragm 60 expands and
34 contracts in a direction generally corresponding to and
parallel with the axis of elongation of the waveguides 20
36 at the projection 62. It will be appreciated that the
37 fluidic reaction of this embodiment including the chamber 14
,,
.

117535~
-- 10 --
l may be reparable from the waveguides 20 at the diaphragm
2 62 in accordance with one important object of the inven-
3 tion.
4 Acoustic waveguides suitable for use in the various
embodiments of this invention include waveguides made of
6 such material as tungsten, stainless steel or titanium, or
7 other hard materials such as ceramics, or glass fibers.
8 In choosing an acoustic waveguide, it is particularly im-
9 portant that the transmissibility of the waveguide material
be a maximum for acoustic waves and its strength also be a
11 maximum.
12 The mechanism by which the waveguides operate in
13 conjunction with the transducer may be described as follows.
14 An electrical pulse arrives at the transducer. The trans-
ducer first retracts (fill cycle) and then expands. The
16 retraction, followed by expansion results in displacements
17 at the transducer face, which are imposed at the end of the
18 waveguide which is touching the transducer. Depending on
l9 the rise-time of the pulse, part of the end of the waveguide
~20 will be compressed elastically. This initial compression
21 wilI launch a compressional impulse along the waveguide
22 with a speed equal to the speed of sound in the material
23 of the waveguide. At a later time (corresponding to
24 approximately 2~ sec in a 2.54 cm steel guide), the impulse
25 ~will arrive at the distal end of the waveguide; it will,
26 thus, alter the volume of the chamber and generate dropletsO
27 The physical mechanism involved in truning the pulse
~;28 generated by the transducer into a mechanical impulse may
29 be explained using a unit step excitation analysis or a unit
im ulse excitation analYsis as follows:
p _ _
31 UNIT STEP EXCITATION
32 Herej a constant force Fo, is assumed to be applied
33 suddenly at time = 0 to a waveguide that is at rest ini-
34 tially. The usual equation of motion is:
';: '~ '

~175359
1 d x dx
2 m - + c - + kx = Fo for t>o
3 dt dt
4 with the solution of:
Fo -~ Xe - 3Wnt sin ( ~ Wnt ~
6 This must satisfy the initial conditions X = dXt = at t = o
1 2
7 ~ i-~ Fo
8 tg ~= - and X = r__~
9 ~ k~
Then:
Wnt r~-~~
12. x = Fo [1- e sin(~ 1-~ Wnt + ~)].
13 k ~
14 Here: Wn = frequency of the transient (W = 2 ~ f).
~ = damping factor (lossiness)
16 t = time (sec)
17 Fo = force applied (impulse) in dynes
18 ~ m = mass (gr).
19 k = spring constant assuming the guide deforma-
tion remains within the elastic limit of
21 the material.
22 k = 1 where: E = Young's Modulus in ~
23~ A = cross section area in (cm )
24 ~ ~ 1 = length in ~cm).
;25~ ~ also, C2m = ~Wn, where C is the damping.
: ::
26 UNIT IMP~SEEXCITATION
27 An impulse, I, is defined as a large force acting
28 for a very short time which can never be rigorously realized
29 in practice. However, it is useful to assume this case
because it provides insight into the understanaing of wave-
31 guide operation. Thus, as stated: lim ~ at ~ o
h 32
.,

~7S35~
This impulse produces an initial velocity in the small
short portion mass (m) adjacent to the transducer end. This
velocity is vO = I/m, and the displacement may be considered
equal to zero. Thus, the differential equation for t~o with the
right side equal to O the solution:
x = xe-~Wnt ~in~ ~ Wnt_~)
is fitted to:
dx = I ~at t=~) and x=o
Then: I
X = r~ for ~ = o
~ km(1-~ )
Thus, the displacement, x, at any time, t, is:
X = ~ e sin ~ Wnt
With peak displacement given by:
tg ~ Wn~ =
~: B
The Kinetic energy provided by unit impul~e on the first
end of ~he waveguide is derived as follow~:
An impulse, I, from the transducer hits the portion of
mass in the waveguide and generates thereon a velocity, V.
Assuming the waveguide had an initial velocity, VO~ we have, for
a velocity change:
m~V - VO) = I
multiplying both side~ by 1~2 (V + VO)
1/2 mV2 - 1/2 m~ = Itl/2(V-Vo)~
If no initial v~locity i~ assumed ~VO = O),
~-d - 12 -

~L75359
1/2 mV2 ~ 1/2 IV = kinetic energy (in CGS units~.
The foregoing is a general description o~ how a single
(impulse~ is intxoduced into a wave~uide. In what follow~, an
analysis i8 made on what happens when an impulse travel~ along a
waveguide.
- 12a -

:~753S~
`~ ~
When a mechanical impulse of amplitude, ~, travels along
a wavegulde medium, it w~ll have a particle velocity v a~ a time,
t~ and a displacement pos~tion, x. The di~placement, b, a~ a time,
t, o~ a particle whose initial po~ition i8, X, will be:
b - as~n2 ll~t - x) = esin2 Jl~ft-x~
Here: T - period ~sec)
f ~ ~requencytsec 1)
wave length ( impulse leading edge, pulse width,
trailing edge)
~ - particle di~placement amplitude.
Since: . -
v - ~A and w ~ 2nf
Then: x
b ~ ~s~n 2A ~ X) a asin w~t-v-)
The particle velocity is:
db _ Gw co~ w (t v)
Assuming a layer o~ thickne3~, dx, who~e wa~ is pdx
(wherep - density~. The klne~ic energy (KE) o~ ~his layer i~
dE 3 ~ [~ pdx~,2w2cog2w [~-Xv~
where dE i a small increment of the kinetic en~rgy.
The KE of the whole wave syst~m i~:
E ' 2 pa2w2lc~2w~t_x)dx
The total energy of the impul~e motion per unit volume
i~i2
E - 1~2pa2w2 ~-energy den~ity) ~ 2~2p2~2~2
Thu~, in thin wire~, one gets large di~placement~ and the
energy i~ transmittable if it stay~ within the wire.
The intensity of the pulse i~ energy transmission
per second per uni~ arga o~ wave front. Then it
- 13 -

~L~t75;3~9
equals energy density E x velocity V.
I ~ 1 pa2w2v = a2w2~pv)
The varying compre~sional pressure P at any point relates
to par~icle velocity in the medium as follows:
~ ) pv K ~contstanl) depending on the
The energy loss from the guide into the environment i~Q
calculated by:
R2 ~ R
R2 ~ R
Where R i9 the total reflected en~rgy f,rom the environment
surrounding the waveguide and the material o~ the waveguide, Rl,
is the reflected energy from the material and R2 is the reflected
: energy in the environment surrounding the waveguide.
: Making Rl = plCl where Pl = density of the waveguide
m~terial in (~_) and Cl = wave velocity in said material.
cm
Fvr steel: Rl = PlCl = 7.9 x S.2 x 105 _ 4.1 x 106.
R2 P2C2 .35 x 10 .
Whera ~ is~the density of air or material surrounding the wave~
guide.
~ Hence, 1 - R = .0164.
: which is the amount lost from the waveguide per unit length and
: ~ which is quite small.
: The energy attenuation due to bending is calculated by
A. E. H. Love in hia Tre tise of the Mathemati¢al Theory of
Elasticity. Dover (1944). From this calculation, it may be con-
14 -

~1753S~31
cluded that all of the energy would be transmitted along a bent
waveguide if the bending radiu~ i5 equal to or greater than a
quarter wave of the vibrating power for the material of the wave-
guide.
::
~ 14a ~
~ .

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2024-08-01 : Dans le cadre de la transition vers les Brevets de nouvelle génération (BNG), la base de données sur les brevets canadiens (BDBC) contient désormais un Historique d'événement plus détaillé, qui reproduit le Journal des événements de notre nouvelle solution interne.

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Historique d'événement

Description Date
Inactive : CIB désactivée 2011-07-26
Inactive : CIB de MCD 2006-03-11
Inactive : CIB de MCD 2006-03-11
Inactive : CIB de MCD 2006-03-11
Inactive : CIB dérivée en 1re pos. est < 2006-03-11
Inactive : Périmé (brevet sous l'ancienne loi) date de péremption possible la plus tardive 2001-11-19
Inactive : Renversement de l'état périmé 2001-10-03
Inactive : Périmé (brevet sous l'ancienne loi) date de péremption possible la plus tardive 2001-10-02
Accordé par délivrance 1984-10-02

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EXXON RESEARCH AND ENGINEERING COMPANY
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Revendications 1993-12-15 4 117
Page couverture 1993-12-15 1 19
Abrégé 1993-12-15 1 11
Dessins 1993-12-15 3 97
Description 1993-12-15 17 636