CA1155165A - Nozzles for pressure pulse drop ejectors - Google Patents
Nozzles for pressure pulse drop ejectorsInfo
- Publication number
- CA1155165A CA1155165A CA000324979A CA324979A CA1155165A CA 1155165 A CA1155165 A CA 1155165A CA 000324979 A CA000324979 A CA 000324979A CA 324979 A CA324979 A CA 324979A CA 1155165 A CA1155165 A CA 1155165A
- Authority
- CA
- Canada
- Prior art keywords
- meniscus
- nozzle
- fluid
- section
- drop
- 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
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
- B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
- B41J2/01—Ink jet
- B41J2/135—Nozzles
- B41J2/14—Structure thereof only for on-demand ink jet heads
- B41J2002/14475—Structure thereof only for on-demand ink jet heads characterised by nozzle shapes or number of orifices per chamber
Landscapes
- Particle Formation And Scattering Control In Inkjet Printers (AREA)
- Nozzles (AREA)
- Special Spraying Apparatus (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A nozzle for use with a pressure pulse drop ejector system, which is relatively insensitive to nozzle orifice rim imperfections, and which provides reduced meniscus vibration facilitating a higher rate of drop formation. The nozzle is widened at the outlet orifice end. This removes the line of shear during drop formation from the fluid-solid interface to the fluid itself.
A nozzle for use with a pressure pulse drop ejector system, which is relatively insensitive to nozzle orifice rim imperfections, and which provides reduced meniscus vibration facilitating a higher rate of drop formation. The nozzle is widened at the outlet orifice end. This removes the line of shear during drop formation from the fluid-solid interface to the fluid itself.
Description
115~
BRIEF SUMMARY OF THE _INVENTION
The invention can be utilized in any pressure pulse drop ejector system; however, the greatest benefits are realized when the nozzles made in accordance with the present invention are used in an ink jet recording system. Accordingly, the present invention will be described in connection with an ink jet reco~ding system.
When an ink droplet is expressed from an outlet orifice, the new meniscus formed by the remaining fluid in the orifice vibrates until it reaches a stable condition.
Since the meniscus must be stabilized in order to express controlled droplets, the duration of the vibration affects the frequency at which controlled volume droplets can be expressed from the orifice. The longer the duration of vibration, the lower the frequency of acceptable operation. The problem is discussed in detail in commonly owned U.S. Patent 4,024,544.
Further, it has been found in ink jet recording systems that even relatively minor defects, such as chips or cracks in drop outlet orifice rims, can cause relatively large trajector~ errors. q'rajectory errors in an ink jet recording system can cause poor quality reproductions and can even render the system unusable.
Nozzles designed in accordance with the present invention provide meniscus vibration damping and are relatively not affected by orifice rim defects.
An aspect of the invention is as follows:
A nozzle for a pressure pulse drop ejector system, which comprises a throat section and an enlarged meniscus section in which a meniscus is formed in a fluid in said meniscus section, the relationship between the meniscus section and the throat section being such ,~t` ~ - 2 -llS51t~5 that drop formation shear occurs as fluid-to-fluid shear.
BRIEF DESCRIPTION OF THE DRAWINGS
_ FIG. lA and lB are side sectional schematic representations of the operation of nozzles in accordance with prior art.
FIG. 2A and 2B are side sectional schematic - 2a-'~G
;''"'~
1~551~i5 representations of the operation of nozzles in accordance with the present invention.
Referring now to FIG. lA, there is shown housing 10 having nozzle 12 formed therein. Nozzle 12 is filled with fluid 14 which, in its rest condition, forms meniscus 16.
FIG. lB illustrates the typical shape of the meniscus 16 when fluid 14 has been acted upon by a pressure pulse but before drop separation has occurred. The purpose of FIG. lB is to illustrate that in conventional nozzles, part of the fluid which forms the drop is in contact with solid material. The drag between the fluid and the solid material influences drop formation. Any defect, such as a chip or crack in the orifice material since it is in contact with the fast moving fluid material, can cause the drop to be expelled at an angle rather than, for example, straight; i.e., cause trajectory errors.
Referring now to FIG. 2A, there is shown housing 20 and a nozzle 22 formed therein in accordance with the present invention. Nozzle 22 has been widened at the orifice outlet to form an enlar~ed meniscus area. For purposes o discussion, the nozzle diameter before the enlargement will be referred to as the throat diameter shown as Dt in FIG. 2. The enlarged outlet orifice diameter will be referred to as the meniscus diameter shown as Dm in FIG. 2. FIG. 2B illustrates the key feature of the instant invention. The drop which is being formed is formed of fast moving fluid, which is not in contact with solid material at the time of drop formation and drop separation.
There is an area represented by a in FIG. 2A of relatively slow or stagnant fluid formed between the fast moving fluid and the orifice rim. The drop formation shear accordingly occurs as fluid-to-fluid shear rathe, than a fluid-to-solid shear.
1~55~S
The separation of the fluid, which forms the drop from the rim of the outlet orifice, minimizes or eliminates drop trajectory error caused by rim imperfections. It has also been found that increasing the meniscus area reduces the amplitude of meniscus vibration,and decreasing the throat area increases meniscus vibration damping. When a drop is expressed, a new meniscus is formed. This new meniscus vibrates for a time before coming to rest. It is only when the meniscus is at rest that an accurately sized drop can be expressed. Accordingly, the amount of time that it takes the meniscus to come to rest determines how fast the ink jet system can function. The improvement in meniscus damping occurs because the meniscus area is made independent of the throat area. Meniscus vibration decays in a manner dependent upon the compliance of the meniscus and the inertance and resistance of the nozzle. The compliance is a function of:
(meniscus cross-sectional area)2 (fluid surface tension) Inertance is a function of:
(fluid density)(nozzle len th) (throat cross-sectlonal area)~~
The nozzle resistance is a function of:
(fluid viscosity)(nozzle length) (throat cross-sectional area)~~
There is one relationship among design variables that achieves critical damping or the shortest time for meniscus relaxation.
For a given meniscus disturbance to be relaxed in the shortest time, the fluid "circuit" representing the pressure pulse drop ejector must be critically damped. ~ince the throat cross-sectional area, which determines resistance and inertance, can, according to the invention, be independently chosen from the meniscus cross-sectional area, which controls compliance, li55~6~
selection of these cross-sectional areas can be made to substan-tially achieve critical damping of the meniscus. As an example, a 20 ~um diameter throat having a 20 ~m deep, 40 ,um diameter ou let has a damping time one fourth that of a 40Jum straight nozzle.
The degree of damping can be measured by observing the meniscus through a microscope during either sinusoidal or pulsed jet excitation. It is thus relatively simple to compare meniscus damping in different nozzle designs. Such measurements have confirmed the teaching of this invention.
A further advantage of the improved nozzle is that the surface of the material from which the nozzle is formed need not be of a special wetting or non-wetting character since the rim of the meniscus forming area is remote from the fast-moving fluid which forms the drops shown in FIG. 2B.
Referring again to prior art FIG. lB, it is seen that the meniscus forms almost a 90 angle between the jet of ink and the outer nozzle surface. FIG. 2B conversely shows that the meniscus at the point of contact with the nozzle surface maintains an approximately 180 angle even during ejection. Hence, there is much greater resistance to wetting of the outer jet surface.
A typical nozzle in accordance with the present invention would have a throat diameter of about 20 ~m to about 80 ~um. The diameter of the meniscus would be from about 12 ~m to about 25 ~m larger than the throat diameter. The ratio of the area of the enlarged area to the area of the throat area is accordingly from about 1.5:1 to about 5 1. The depth of the enlarged area would be typically between about 25 ,um and about 50~um deep. Although the above measurements were given as diameters inferring circular cross-sectional areas, the throat cross-section and the meniscus cross-section can he triangles, ~L15Sl~S
squares, rectangles or any conveniently formed shape and need not be the same. Further, the enlarged space may be cylindrical, conical or any conveniently formed shape and need not even be coaxial or concentric with the nozzle throat.
BRIEF SUMMARY OF THE _INVENTION
The invention can be utilized in any pressure pulse drop ejector system; however, the greatest benefits are realized when the nozzles made in accordance with the present invention are used in an ink jet recording system. Accordingly, the present invention will be described in connection with an ink jet reco~ding system.
When an ink droplet is expressed from an outlet orifice, the new meniscus formed by the remaining fluid in the orifice vibrates until it reaches a stable condition.
Since the meniscus must be stabilized in order to express controlled droplets, the duration of the vibration affects the frequency at which controlled volume droplets can be expressed from the orifice. The longer the duration of vibration, the lower the frequency of acceptable operation. The problem is discussed in detail in commonly owned U.S. Patent 4,024,544.
Further, it has been found in ink jet recording systems that even relatively minor defects, such as chips or cracks in drop outlet orifice rims, can cause relatively large trajector~ errors. q'rajectory errors in an ink jet recording system can cause poor quality reproductions and can even render the system unusable.
Nozzles designed in accordance with the present invention provide meniscus vibration damping and are relatively not affected by orifice rim defects.
An aspect of the invention is as follows:
A nozzle for a pressure pulse drop ejector system, which comprises a throat section and an enlarged meniscus section in which a meniscus is formed in a fluid in said meniscus section, the relationship between the meniscus section and the throat section being such ,~t` ~ - 2 -llS51t~5 that drop formation shear occurs as fluid-to-fluid shear.
BRIEF DESCRIPTION OF THE DRAWINGS
_ FIG. lA and lB are side sectional schematic representations of the operation of nozzles in accordance with prior art.
FIG. 2A and 2B are side sectional schematic - 2a-'~G
;''"'~
1~551~i5 representations of the operation of nozzles in accordance with the present invention.
Referring now to FIG. lA, there is shown housing 10 having nozzle 12 formed therein. Nozzle 12 is filled with fluid 14 which, in its rest condition, forms meniscus 16.
FIG. lB illustrates the typical shape of the meniscus 16 when fluid 14 has been acted upon by a pressure pulse but before drop separation has occurred. The purpose of FIG. lB is to illustrate that in conventional nozzles, part of the fluid which forms the drop is in contact with solid material. The drag between the fluid and the solid material influences drop formation. Any defect, such as a chip or crack in the orifice material since it is in contact with the fast moving fluid material, can cause the drop to be expelled at an angle rather than, for example, straight; i.e., cause trajectory errors.
Referring now to FIG. 2A, there is shown housing 20 and a nozzle 22 formed therein in accordance with the present invention. Nozzle 22 has been widened at the orifice outlet to form an enlar~ed meniscus area. For purposes o discussion, the nozzle diameter before the enlargement will be referred to as the throat diameter shown as Dt in FIG. 2. The enlarged outlet orifice diameter will be referred to as the meniscus diameter shown as Dm in FIG. 2. FIG. 2B illustrates the key feature of the instant invention. The drop which is being formed is formed of fast moving fluid, which is not in contact with solid material at the time of drop formation and drop separation.
There is an area represented by a in FIG. 2A of relatively slow or stagnant fluid formed between the fast moving fluid and the orifice rim. The drop formation shear accordingly occurs as fluid-to-fluid shear rathe, than a fluid-to-solid shear.
1~55~S
The separation of the fluid, which forms the drop from the rim of the outlet orifice, minimizes or eliminates drop trajectory error caused by rim imperfections. It has also been found that increasing the meniscus area reduces the amplitude of meniscus vibration,and decreasing the throat area increases meniscus vibration damping. When a drop is expressed, a new meniscus is formed. This new meniscus vibrates for a time before coming to rest. It is only when the meniscus is at rest that an accurately sized drop can be expressed. Accordingly, the amount of time that it takes the meniscus to come to rest determines how fast the ink jet system can function. The improvement in meniscus damping occurs because the meniscus area is made independent of the throat area. Meniscus vibration decays in a manner dependent upon the compliance of the meniscus and the inertance and resistance of the nozzle. The compliance is a function of:
(meniscus cross-sectional area)2 (fluid surface tension) Inertance is a function of:
(fluid density)(nozzle len th) (throat cross-sectlonal area)~~
The nozzle resistance is a function of:
(fluid viscosity)(nozzle length) (throat cross-sectional area)~~
There is one relationship among design variables that achieves critical damping or the shortest time for meniscus relaxation.
For a given meniscus disturbance to be relaxed in the shortest time, the fluid "circuit" representing the pressure pulse drop ejector must be critically damped. ~ince the throat cross-sectional area, which determines resistance and inertance, can, according to the invention, be independently chosen from the meniscus cross-sectional area, which controls compliance, li55~6~
selection of these cross-sectional areas can be made to substan-tially achieve critical damping of the meniscus. As an example, a 20 ~um diameter throat having a 20 ~m deep, 40 ,um diameter ou let has a damping time one fourth that of a 40Jum straight nozzle.
The degree of damping can be measured by observing the meniscus through a microscope during either sinusoidal or pulsed jet excitation. It is thus relatively simple to compare meniscus damping in different nozzle designs. Such measurements have confirmed the teaching of this invention.
A further advantage of the improved nozzle is that the surface of the material from which the nozzle is formed need not be of a special wetting or non-wetting character since the rim of the meniscus forming area is remote from the fast-moving fluid which forms the drops shown in FIG. 2B.
Referring again to prior art FIG. lB, it is seen that the meniscus forms almost a 90 angle between the jet of ink and the outer nozzle surface. FIG. 2B conversely shows that the meniscus at the point of contact with the nozzle surface maintains an approximately 180 angle even during ejection. Hence, there is much greater resistance to wetting of the outer jet surface.
A typical nozzle in accordance with the present invention would have a throat diameter of about 20 ~m to about 80 ~um. The diameter of the meniscus would be from about 12 ~m to about 25 ~m larger than the throat diameter. The ratio of the area of the enlarged area to the area of the throat area is accordingly from about 1.5:1 to about 5 1. The depth of the enlarged area would be typically between about 25 ,um and about 50~um deep. Although the above measurements were given as diameters inferring circular cross-sectional areas, the throat cross-section and the meniscus cross-section can he triangles, ~L15Sl~S
squares, rectangles or any conveniently formed shape and need not be the same. Further, the enlarged space may be cylindrical, conical or any conveniently formed shape and need not even be coaxial or concentric with the nozzle throat.
Claims (3)
1. A nozzle for a pressure pulse drop ejector system, which comprises a throat section and an enlarged meniscus section in which a meniscus is formed in a fluid in said meniscus section, the relationship between the meniscus section and the throat section being such that drop formation shear occurs as fluid-to-fluid shear.
2. The nozzle of Claim 1, wherein said meniscus section has a cross-sectional area of from about 1.5 to about 5 times the cross-sectional area of the throat section.
3. The nozzle of Claim 1, wherein said throat section has a diameter of about 20 µm to about 80 µm, and said meniscus section has a diameter of from about 12 µm to about 25 µm larger, and said meniscus section is from about 25 µm to about 50 µm deep.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US91080278A | 1978-05-30 | 1978-05-30 | |
| US910,802 | 1978-05-30 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1155165A true CA1155165A (en) | 1983-10-11 |
Family
ID=25429346
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000324979A Expired CA1155165A (en) | 1978-05-30 | 1979-04-05 | Nozzles for pressure pulse drop ejectors |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPS54156209A (en) |
| CA (1) | CA1155165A (en) |
| DE (1) | DE2915886A1 (en) |
| GB (1) | GB2022021B (en) |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4233610A (en) * | 1979-06-18 | 1980-11-11 | Xerox Corporation | Hydrodynamically damped pressure pulse droplet ejector |
| US4587534A (en) * | 1983-01-28 | 1986-05-06 | Canon Kabushiki Kaisha | Liquid injection recording apparatus |
| JPS59162057A (en) * | 1983-03-03 | 1984-09-12 | Fujitsu Ltd | Ink-jet print head |
| US4599626A (en) * | 1984-08-02 | 1986-07-08 | Metromedia, Inc. | Ink drop ejecting head |
| DD250091B1 (en) * | 1986-06-18 | 1989-09-20 | Robotron Bueromasch | INK JET PRINT HEAD WITH DYNAMICALLY FLUSHED DUESEN PREORUMS |
| GB8722085D0 (en) * | 1987-09-19 | 1987-10-28 | Cambridge Consultants | Ink jet nozzle manufacture |
| DE4115504A1 (en) * | 1991-05-11 | 1992-11-12 | Braun Ag | NOZZLE, ESPECIALLY FOR A GAS-OPERATED DEVICE OF PERSONAL NEED |
| ATE226146T1 (en) | 1999-01-29 | 2002-11-15 | Seiko Epson Corp | INKJET PRINT HEAD WITH IMPROVED INK FEED CHANNELS |
| DE10236885A1 (en) * | 2002-08-12 | 2004-02-26 | Valeo Auto-Electric Wischer Und Motoren Gmbh | Nozzle head for wash nozzle for use with vehicles has spherical nozzle head body which by its fluid feed channel and outlet orifices is made in one piece from suitable material and especially from plastic, metal, glass or ceramic |
-
1979
- 1979-04-05 CA CA000324979A patent/CA1155165A/en not_active Expired
- 1979-04-19 DE DE19792915886 patent/DE2915886A1/en not_active Withdrawn
- 1979-05-21 GB GB7917576A patent/GB2022021B/en not_active Expired
- 1979-05-23 JP JP6376379A patent/JPS54156209A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| GB2022021B (en) | 1982-05-06 |
| JPS54156209A (en) | 1979-12-10 |
| GB2022021A (en) | 1979-12-12 |
| DE2915886A1 (en) | 1979-12-13 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |