US3921179A

US3921179A - Fluid pen assembly

Info

Publication number: US3921179A
Application number: US351222A
Authority: US
Inventors: Ronald J Weerstra
Original assignee: Xerox Corp
Current assignee: Xerox Corp
Priority date: 1973-04-16
Filing date: 1973-04-16
Publication date: 1975-11-18
Anticipated expiration: 1992-11-18
Also published as: USB351222I5

Abstract

A non-wearing pen or stylus arrangement for use in electrographic recording apparatus comprising a container filled with an electrically conductive liquid which will not wet the surface of a recording medium. The liquid is made to form a meniscus which is in contact with a moving recording medium. An electrode is immersed in the liquid to permit conduction of electric charge from a source through the electrode and liquid onto the surface of the recording medium.

Description

United States Patent 1191 Weerstra Nov. 18, 1975 [5 FLUID PEN ASSEMBLY 1,827,362 10/1931 Hiltz et al. 235/61.ll A Inventor: Ronald J. s' a, Clare, M ch. 3,626,422 12/1971 Lloyd 346/74 ES 73 A X C t' Sslgnee 22: orpora Stamford Primary Examiner-Thomas A. Robinson [22] Filed: Apr. 16, 1973 21 App]. No.: 351,222 [57] ABSTRACT [44] Published under the Trial Voluntary Protest f Program on January 28, 1975 as document no. A non'weanpg pen f Stylus arrangemenl use m B 351 222 electrographic recording apparatus comprismg a container filled with an electrically conductive liquid [52] U S 346/74 235/61 11 200/193 which will not wet the surface of a recording medium. [51] G03G 15/00 The liquid is made to fon'n a meniscus which is in [58] Fieid 4 Es 139 0 contact with a moving recording medium. An elec- 200/193 11 A 6 H 178/87 trode is immersed in the liquid 'to permit conduction of electric charge from a source through the electrode [56] References Cited and liquid onto the surface of the recording medium. UNITED STATES PATENTS 10 Claims, 1 Drawing Figure 1,711,497 5/1929 l-liltz et al. 235/6l.ll A I US. Patent Nov. 18, 1975 3,921,179

. I FLUID PEN ASSEMBLY substantially eliminated.

In electrographic recording a charge pattern corresponding to information to be recorded is deposited on a recording medium. The recording medium generally comprises an electrically conductive base paper on which a dielectric material of high resistivity is coated. The charge is deposited on the recordingmedium by means of a stylus held at a potential of several hundred volts with respect to a backing platen. The accumulation of charges on the dielectric surface and the induced opposite charge at the dielectric base interface create a strong field through the dielectric coating. A varietyof flexible web-shaped materials are available for use in accepting the electrostatic charge. The recording medium may also be a dielectric rotatable drum, as are well known inthe prior art.

The latent electrostatic image produced above may be rendered visible by the deposition of suitably charged and colored development particles on the recording medium. Heat is subsequently applied to fix or make permanent the visible image.

The pen or stylus used for charge deposition, is connected to a source of input signals which vary the charge to be deposited on the paper in correspondence to the information to be recorded. The recording paper is generally moved across the fixed tip of a pen or stylus to properly deposit the information on the recording medium.

In order to provide for an acceptable transfer of charge in an electrographic system, a certain minimum contact pressure must be maintained between the paper and the stylus. This contact pressure results in friction between the recording medium and the stylus resulting in eventual wear of the stylus or the medium or both.

Various attempts at reducing the wear have centered around reducing the speed at which the recording medium moves relative to the stylus and utilizing a stylus or medium of increased hardness. The former approach has the disadvantage of reducing the speed of the recording process, while the latter necessitates increased costs for materials.

OBJECTS AND SUMMARY OF THE INVENTION It is therefore an object of the invention to provide a stylus or writing instrument arrangement for electrographic recording which is less subject to excessive wear due to the friction between the writing instrument and the moving recording medium.

A further object is to provide a stylus comprising a liquid conductor which acts as the charge transfer intermediary.

A further object of the invention is the provision of a stylus for electrographic recording which comprises relatively few moving parts.

Other objects and advantages may be appreciated from the simplicity, economy and efficiency of the prebetween the pen and the recording medium may be 2 ferred embodiment which will become apparent upon understanding of the details thereof.

These and other objects of the invention are realized by a stylus comprising a cylindrical tube filled with an electrically conductive liquid which does not wet the surface of the recording medium. The liquid is placed under sufficient pressure so as to provide a meniscus which protrudes into contact with the recording medium. An electrode is immersed in the liquid via which current is passed through the liquid onto the recording medium in correspondence with information to be recorded.

BRIEF DESCRIPTION OF THE VIEWS The drawing diagrammatically illustrates the construction of the new stylus of the invention in an electrical recording system.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawing, there is shown a transport arrangement for moving a web-shaped recording medium 2, such as paper, in the direction indicated by the arrows in the drawing past a recording stylus 3, accord-. ing to the invention. The transport arrangement is shown in the drawing as including three rollers 4, 5 and 6 which rotate in the directions shown. The roller 6 may be spring biased so as to maintain a constant contact between the recording medium 2 and the tip of the stylus arrangement 3.

The stylus arrangement 3 is shown as comprising a U-shaped glass container 7 filled with an electrically conductive liquid 11. The container 7 may be cylindrical in cross-section and have a narrow diameter portion 8 located adjacent the recording medium 2 and a wider diameter portion 9 remote from the recording medium 2. The liquid 11 is of a type which will not wet the surface of the recording medium 2 being used when in contact therewith. The wider diameter portion 9 of the container 7 serves as a reservoir and is filled to a suitable level to provide a meniscus 10 which protrudes above the topmost lip of the narrow diameter portion 8. The container 7 may be supported by structure (not shown) of an appropriate design to maintain the meniscus 10 of the liquid in contact with the recording medium 2.

An electrode 12 is immersed in the liquid and is connected to one side of an input signal generating means 13. The other side of the signal generator 13 is suitably grounded or held at an appropriate reference potential. The roller 6 or at least the surface of the roller in contact with the back side of the recording medium is held at an appropriate electrical potential so as to allow the proper deposition of electrical signals on the recording paper in accordance with variations in the magnitude of the input signal generator means 13.

In operation, an electrical signal is generated by the source 13 which varies in correspondence with the information to be recorded. This signal is impressed across the meniscus l0 and the recording medium 2 via the electrode 12, resulting in the flow of charge onto the medium in proportion to the variations in the source. A latent static charge pattern is therefore deposited on the moving web which corresponds to the information to be recorded. The latent charge pattern may then be made visible by means (not shown) of the conventional technique of applying colored development particles of suitable affinity to the paper, which 3 particles adhere to charged portions of the paper. The particles are then fused to the paper to produce a permanent record of the information.

The use of mercury as the electrically conductive liquid 11 in the above-described arrangement has given satisfactory results,-but it is to be understood that various other liquid metals may be used in place of mercury.

The area of contact between the recording medium and the liquid 11, and consequently, the width of the printed line, may be controlled by varying the diameter of the narrow diameter section 8 of the container. Commercially available capillary tubes may be utilized to' hold the liquid with suitable level control arrangements used to vary the height of the liquid in the capillary tubes. These arrangements, in order to effect a change in the height of the liquid, generally vary the pressure applied to the liquid or insert solid plunger devices into' the liquid to thereby displace it.

While this application has emphasized that the recording medium may be an electrographic paper, it should be understood that various recording media capable of accepting surface charges may be utilized. For example, a dielectric rotating drum may be used for the same purpose, the glass coating being in contact with the stylus arrangement of the invention.

It should be understood that in its broadest aspects, the invention proposes a novel sliding electrical contact arrangement with reduced wear. In this sense, the moving recording medium may be replaced by any moving conductor to which current is to be transferred from a stationary source.

While the invention has been disclosed with reference to a single tube and meniscus, it should be understood that a plurality of such tubes may be spaced across the width of the recording medium. Furthermore, while the stylus arrangement of the invention has beenillustrated as being stationary, it should be understood that means may be provided for moving the stylus while holding the recording medium stationary.

What is claimed is:

1. A stylus arrangement for applying a charge to a recording medium comprising a container having an opening therein adjacent one side of said medium,

a liquidin said container arranged to form a convex meniscus extending beyond said opening and contacting said one side of said medium, said liquid being electrically conductive and non-wettable to said one side of said medium,

means for providing relative motion between said styfirst electrode means on the other side of said medium, o.

second electrode means immersed in said liquid, said second electrode means being coupled to an electrical signal'source, whereby electrical signals from said source result in passage of charge to said recording medium via s'aid second electrode means 7 and liquid.

2. The combination recited in' claim 1 wherein said container comprises a U-shaped cylinder having a large diameter at one end thereof and a small diameter at the other end thereof forming said opening.

3. The combination recited in claim 1 wherein said medium comprises a dielectric paper having a conductive base surface and a high resistivity upper surface in contact with said meniscus.

4. The combination recited in claim 1 wherein said liquid comprises mercury.

5. The combination recited in claim 1 wherein the electrical signals from said source vary in magnitude.

6. Recording apparatus comprising a recording medium, I

a container having an opening therein adjacent one side of said medium, an electrically conductive fluid in said container forming a convex menisucs at one end thereof extending beyond said opening and contacting said one side of said medium,

means for moving said medium in contact with said meniscus, said fluid being non-wettable to said medium,

a source emitting electrical signals-in accordance with information to be recorded, and

means for connecting said source across said fluid and said recording medium whereby an electrical charge is deposited on said recording medium in accordance with said electrical signals.

7. The combination recited in claim 6 wherein said fluid is mercury.

8. The combination recited in claim 7 wherein said container comprises a U-shaped cylinder having said opening of relatively narrow diameter and a reservoir 9. The combination recited in claim 7 wherein said connecting means for said source includes an electrode Ins and said medium, with said meniscus in contact with said medium, and

immersed in said mercury and connected to said source.

10. The combination as recited in claim 6 wherein the electrical signals emitted from said source vary in magnitude thereby depositing a charge on said recording medium in accordance with the variations in the signal magnitude.

Claims

1. A stylus arrangement for applying a charge to a recording medium comprising a container having an opening therein adjacent one side of said medium, a liquid in said container arranged to form a convex meniscus extending beyond said opening and contacting said one side of said medium, said liquid being electrically conductive and non-wettable to said one side of said medium, means for providing relative motion between said stylus and said medium, with said meniscus in contact with said medium, and first electrode means on the other side of said medium, second electrode means immersed in said liquid, said second electrode means being coupled to an electrical signal source, whereby electrical signals from said source result in passage of charge to said recording medium via said second electrode means and liquid.

2. The combination recited in claim 1 wherein said container comprises a U-shaped cylinder having a large diameter at one end thereof and a small diameter at the other end thereof forming said opening.

4. The combination recited in claim 1 wherein said liquid comprises mercury.

6. Recording apparatus comprising a recording medium, a container having an opening therein adjacent one side of said medium, an electrically conductive fluid in said container forming a convex menisucs at one end thereof extending beyond said opening and contacting said one side of said medium, means for moving said medium in contact with said meniscus, said fluid being non-wettable to said medium, a source emitting electrical signals in accordance with information to be recorded, and means for connecting said source across said fluid and said recording medium whereby an electrical charge is deposited on said recording medium in accordance with said electrical signals.

7. The combination recited in claim 6 wherein said fluid is mercury.

8. The combination recited in claim 7 wherein said container comprises a U-shaped cylinder having said opening of relatively narrow diameter and a reservoir port of relatively large diameter.

9. The combination recited in claim 7 wherein said connecting means for said source includes an electrode immersed in said mercury and connected to said source.