Coating processes – Direct application of electrical – magnetic – wave – or... – Electrostatic charge – field – or force utilized
Reexamination Certificate
1999-02-16
2001-04-24
Beck, Shrive (Department: 1762)
Coating processes
Direct application of electrical, magnetic, wave, or...
Electrostatic charge, field, or force utilized
C427S458000, C427S470000, C427S066000, C427S068000, C427S258000, C427S335000, C427S337000, C427S377000, C427S402000
Reexamination Certificate
active
06221438
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method of depositing a material in a pattern, and, more particularly, to selectively depositing charged droplets including display materials onto electrodes.
BACKGROUND OF THE INVENTION
The general concept of patterned deposition of a material onto a substrate has many applications. Some methods of patterned deposition are additive and others are subtractive. Additive methods deposit the material only where desired. In contrast, subtractive methods deposit the material and then selectively remove (subtract) the material exclusive of the desired pattern.
One application of patterned deposition is the patterned deposition of toner particles to reproduce images. Patterned deposition may also be used to deposit patterns of different colored phosphors to form color pixels on the screen of a cathode ray tube (CRT).
Shadowing is an additive method for depositing a pattern of a material onto a substrate. For shadowing, a shadow mask is formed above or on the substrate. The material is then directionally deposited onto the substrate through apertures in the shadow mask. As a result of the deposition being directional, the material is not deposited in the “shadows” of the structure. Thus, the material is deposited in a pattern defined by the portion of the substrate exclusive of the “shadows” and the structure. By varying the direction of deposition, this technique may be used to deposit different patterns of one or more different materials on a single substrate.
Another method of patterned deposition uses a patterned photoconductor to electrostatically attract charged particles of a material onto a pattern on a substrate. For example, as used in photocopiers, a photoconductor is first applied to the substrate. The photoconductor is then electrostatically charged. The charged photoconductor on the substrate is exposed to light in a desired pattern to selectively discharge the photoconductor. Particles of the material (toner), charged to an opposite polarity than the charge of the patterned photoconductor, are brought into proximity with the substrate. The attraction between opposite charges results in the deposition of the toner onto the substrate in the pattern formed by the charged photoconductor. Paper is then brought in contact with the substrate to deposit the patterned toner onto the paper. The paper may then be heated to fuse the toner to the paper.
Another method of patterned deposition may be used for forming patterns of different colored phosphors corresponding to different colors in pixels on the screen of a cathode ray tube (CRT). For example, a photoconductor may be deposited on the screen and then charged. The photoconductor may then be selectively exposed to form a pattern of charge. Oppositely charged phosphor particles of a first color are then formed. Electrostatic attraction causes the phosphor particles of the first color to attach to the screen positions where the charges were selectively deposited. The phosphors may then be secured to the screen by curing. The process may then be repeated to form patterns of additional colors of phosphor on the screen.
For some applications and for some materials it may be desirable to deposit a pattern while the material is in liquid form. Inkjet technology may be used to deposit a liquefied material in a pattern formed by a plurality of positions on a substrate. First, the liquefied material is supplied to the inkjet. The inkjet and the substrate are then positioned so the inkjet output is adjacent one of the plurality of positions on the substrate. The material in the inkjet is then discharged toward the one of the plurality of positions on the substrate. The inkjet is then repositioned and the process is repeated for each of the plurality of positions on the substrate.
The cost and complexity of an inkjet apparatus may increase when the positions on the substrate are small and when the deposition of material must be localized. Material discharged from an inkjet typically disperses once it exits from the inkjet. To localize deposition, the extent of dispersion may be limited by precisely locating the inkjet close to the substrate.
An inkjet method may also be costly when the number of positions on the substrate is large. When material is to be deposited on many distinct positions on the substrate, using an inkjet is costly due to the time necessary to reposition the inkjet in relation to the substrate for deposition at each of the positions. Alternatively, multiple inkjets may be used to simultaneously deposit material at more than one position. This alternative may be cost prohibitive due to the cost of the multiple ink jets and their operating and maintenance costs.
Inkjet deposition of a liquid may be undesirable for depositing a precise quantity of material. After repeated discharges, an inkjet may begin to clog. A clogged inkjet may not discharge as much material as an unclogged inkjet. Thus, the amount of material per discharge may vary from position to position on the substrate, depending on the extent to which the inkjet is clogged at the various positions.
To overcome the shortcomings of conventional methods of patterned deposition, a new method of deposition is provided.
SUMMARY OF THE INVENTION
The present invention provides a method of deposition. A substrate having a plurality of distinct electrodes is provided. A plurality of portions of a material are formed and charged to a first polarity. The plurality of portions of the material are selectively attracted to the first selected electrodes.
According to one aspect of the present invention, the plurality of portions are selectively deposited on the first selected electrodes.
According to another aspect of the present invention, the plurality of portions of the material are deposited on a second substrate disposed adjacent the first selected electrodes.
According to another aspect of the invention, each of the plurality of portions of the material charged to the first polarity is included in one of a plurality of liquid droplets.
According to another aspect of the invention, the charging of at least one of the first selected ones of the plurality of electrodes is selectively controlled responsive to a value corresponding to a quantity of the material attached to the at least one electrodes.
According to another aspect of the invention, the display material corresponds to a first color and material corresponding to a second color is similarly deposited onto second selected ones of the plurality of electrodes.
According to another aspect of the invention, the first selected ones of the plurality of electrodes are charged to one of the second polarity and a neutral polarity while material corresponding to the second color is attracted to the second selected ones of the plurality of electrodes.
According to another aspect of the invention, multiple material layers are formed by deposition of droplets including multiple materials.
According to another aspect of the invention, liquid droplets charged to the second polarity are formed, each droplet including a first solution and a second solution, the first solution including a hole transport material and a first solvent, the second solution including an organic electroluminescent material and a second solvent, wherein at least one of the droplets is selectively attached to at least one of the distinct electrodes wherein the hole transport material and the organic electroluminescent material in the at least one of the plurality of liquid droplets separate before the solvent evaporates to form a hole transport material layer and an organic electroluminescent layer upon the at least one of the distinct electrodes.
The present invention also provides a structure formed using a method according to the present invention. The structure includes a first substrate having a plurality of distinct electrodes and a plurality of portions of a material formed upon each of the plurality of distinct electrodes.
The present invention also provides an apparatus for forming a plurali
Barr Michael
Beck Shrive
Burke William J.
Huq Abhik A.
Sarnoff Corporation
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