Claims
- 1. Apparatus for applying liquid droplets to a surface comprising, a housing including a first liquid chamber for containing a liquid to be applied to a surface and having an associated piezoelectric device for generating short-duration rises of the pressure of liquid in the first liquid chamber, a second liquid chamber communicating with the first chamber through a connecting channel and having a first discharge channel for droplets of said liquid to leave the apparatus, the first discharge channel being in alignment with the connecting channel and in close proximity thereto so that a short-diration pressure rise in the first liquid chamber causes a series of liquid droplets of decreasing size to be expelled through the first discharge channel, the second liquid chamber having a first intake channel connected to a liquid supply source, a pneumatic chamber substantially divided into an inner, disc-like portion formed with a second discharge channel and an outer, annular portion formed with a second intake channel connected to a source of pressurized air, the second discharge channel being in alignment with the first discharge channel and in close proximity thereto, means for providing communication for the liquid supply source with the air supply source to increase the pressure in the liquid in the first discharge channel relative to the pressure at an exit thereof so that the pressurized air is admitted firstly into the annular portion of the pnuematic chamber, then into the disc-like portion thereof and expelled through the second discharge channel in the form of a laminar jet stream, whereby droplets of said liquid of smaller size when expelled through the first discharge channel are accelerated by the jet stream of air at higher speeds than droplets of large size so that said series of droplets lands on said surface substantially at the same instant of time, and means for humidifying the air in the pneumatic chamber to maintain the liquidity of the liquid in the first discharge channel.
- 2. Apparatus as claimed in claim 1, wherein said humidifying means comprises a housing for holding a liquid suitable for imparting moisture to air, a porous member dividing the interior of the housing into an air intake chamber portion and an air outlet chamber portion and partially disposed in the moisture imparting liquid in the housing interior to absorb the liquid, the intake chamber portion communicating with the air supply means and the outlet chamber portion communicating with the second chamber portion, whereby the liquid absorbed by the porous member moists the air passing therethrough as it is admitted from the intake chamber portion to the outlet chamber portion.
- 3. Apparatus as claimed in claim 1 wherein said humidifying means comprises a housing having top, bottom and side walls for holding a liquid suitable for imparting moisture to air, means defining an intake channel connected to the air supply means and disposed adjacent to the bottom wall of the housing to admit the air therefrom into the liquid in the housing, a porous member disposed in the liquid downstream of the admitted air to create air bubbles in the liquid, and an outlet channel adjacent to the top wall of the housing and connected to the second chamber portion.
- 4. Apparatus as claimed in claim 3, wherein said humidifying means further comprises a second porous member disposed between the surface of the liquid and the outlet channel.
- 5. Apparatus for applying liquid droplets to a surface comprising, a housing including a first liquid chamber for containing a liquid to be applied to a surface and having an associated piezoelectric device for generating short-duration rises of the pressure of liquid in the first liquid chamber, a second liquid chamber communicating with the first liquid chamber through a connecting channel and having a first discharge channel for droplets of said liquid to leave the apparatus, the first discharge channel being in alignment with the connecting channel and in close proximity thereto so that a short-duration pressure rise in the first liquid chamber causes a series of liquid droplets to be expelled through the first discharge channel, the second liquid chamber having a first intake channel connected to a liquid supply source, a pneumatic chamber substantially divided into an inner, disc-like portion formed with a second discharge channel and an outer, annular portion formed with a second intake channel connected to a source of pressurized air, the second discharge channel being in alignment with the first discharge channel and in close proximity thereto, and means for providing communication for the liquid supply source with the air supply source to increase the static pressure in the liquid in the liquid supply source to such a degree that the static pressure in the first discharge channel is substantially equal to the static pressure in the space between the first and second discharge channels.
- 6. Apparatus for applying liquid droplets to a surface as claimed in claim 5, wherein the ratio of the diameter of the first discharge channel to that of the second discharge channel is in a range substantially from 2:5 to 4:15.
- 7. Apparatus for applying liquid droplets to a surface as claimed in claim 6, wherein the diameter of said first discharge channel is 40 micrometers.
- 8. Apparatus for applying liquid droplets to a surface as claimed in claim 6, wherein the ratio of the diameter of said first discharge channel to the axial dimension of said disc-like chamber portion is substantially 1:less than 2.5.
- 9. Apparatus for applying liquid droplets to a surface as claimed in claim 8, wherein the axial dimension of said disc-like chamber portion ranges from 10 to 100 micrometers.
- 10. Apparatus as claimed in claim 5, wherein said communicating means includes means for regulating the pressure of the air supplied to said liquid supply source.
Priority Claims (4)
| Number |
Date |
Country |
Kind |
| 49-111279 |
Sep 1974 |
JPX |
|
| 50-34109 |
Mar 1975 |
JPX |
|
| 50-72555 |
Jun 1975 |
JPX |
|
| 50-73469 |
Jun 1975 |
JPX |
|
BACKGROUND OF THE INVENTION
This is a continuation-in-part application of Ser. No. 616,636 filed on Sept. 25, 1975 now abandoned. su
The present invention relates to apparatus for applying fluid droplets to a writing surface, and more particularly to improvement to a mechanism for writing on paper with an ejected colored liquid.
The speed of recording data on paper in, for example, a data processing system is limited for one thing by the capability of the writing mechanism, which in many cases is substantially less than that of the data processing system.
Because of the high speed capability of the ink ejection type writing mechanism, many proposals have been made in which the liquid is discharged onto the paper by application of electrical pulses, the liquid being ejected in a series of pulsed droplets. The speedof the writing mechanism is in turn largely determined by the capability of the liquid responding to the rapidly occurring electrical pulses. However, the voltage of the electrical pulses must be high enough to overcome the resistance offered by the liquid due to its surface tension and viscosity. The range of voltage necessary for driving the writing unit (dynamic range of a writing mechanism) is therefore determined by the resistance of the liquid to the applied pulses. Prior art writing mechanisms have a narrow dynamic range. This resulted in liquid droplets of comparatively large size and therefore satisfactory gradation of image cannot be obtained on the writing surface.
Because of the high operating speed of the writing mechanism, the liquid droplets are ejected onto a sheet of paper which is wrapped around a roller revolving at a high speed. Since a series of droplets is formed upon ejection in response to a single electrical pulse, they tend to land on different localities of the writing surface, thus causing a blur on the image. Furthermore, the high speed revolution of the roller creates a whirl of wind at the surface which would cause dispersion of the ejected droplets.
Therefore, an object of the present invention is to provide an improved liquid applying apparatus which assures a wider dynamic range than is available by the prior art apparatus to thereby decrease the size of droplets to be deposited on the writing surface.
Another object is to provide an improved liquid applying apparatus in which liquid droplets ejected in response to a single pulse are accelerated by a stream of air so that they land on the writing surface at substantially the same instant of time.
A specific object of the invention is to provide a liquid applying apparatus having a pneumatic chamber connected to a source of pressurized air and an improved arrangement for connecting a liquid supply container with the source of pressurized air.
These and other objects are accomplished in accordance with the invention by apparatus having an improved chamber which includes means separating the chamber into a pneumatic chamber portion and a liquid chamber portion, a liquid discharge channel formed in the separating means, an air discharge channel or nozzle axially aligned with the liquid discharge channel, a liquid intake channel in communication with the liquid chamber for the supply of liquid and an air intake channel in communication with the pneumatic chamber portion for the supply of pressurized air. The liquid chamber portion is in contact with a pressure producing means which produces periodic pressure increases in the liquid in the liquid chamber portion. The liquid and air discharge channels are opposite to the pressure producing means for deposition of liquid droplets therethrough onto a writing surface.
The pneumatic chamber portion is a disc-like configuration and the air intake channel is connected at the periphery thereof and the air discharge channel is located at the center thereof. The cross-sectional area of the air discharge channels is selected in relation to the cross-sectional area of the liquid discharge channel in order that a laminar air flow is formed at the exit thereof.
The source of pressurized air is in communication with the liquid supply container to increase the pressure in the liquid in relation to the air pressure. This prevents the intrusion of air into the liquid chamber portion.
US Referenced Citations (3)
Continuation in Parts (1)
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Number |
Date |
Country |
| Parent |
616636 |
Sep 1975 |
|
Patent Grant
4106032
