Incremental printing of symbolic information – Electric marking apparatus or processes – Electrostatic
Reexamination Certificate
1998-04-02
2001-01-23
Tran, Huan (Department: 2861)
Incremental printing of symbolic information
Electric marking apparatus or processes
Electrostatic
C347S114000, C347S115000, C347S153000
Reexamination Certificate
active
06177947
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to an image forming apparatus for producing color images on a receiver comprising field-driven particles.
BACKGROUND OF THE INVENTION
There are several types of field-driven particles in the field of non-emissive displays. One class uses the so-called electrophoretic particle that is based on the principle of movement of charged colloidal particles in an electric field. In an electrophoretic display, the charged particles containing different reflective optical densities can be moved by an electric field to or away from the viewing side of the display, which produces a contrast in the optical density. Another class of field-driven particles are particles carrying an electric dipole. Each pole of the particle is associated with a different optical densities (bi-chromatic). The electric dipole can be aligned by a pair of electrodes in two directions, which orient each of the two polar surfaces to the viewing direction. The different optical densities on the two halves of the particles thus produces a contrast in the optical densities.
To produce a high quality image it is essential to form a plurality of image pixels by varying the electric field on a pixel wise basis. The electric fields can be produced by a plurality pairs of electrodes embodied in the receiver as disclosed in U.S. Pat. No. 3,612,758. A shortcoming is that this solution requires the incorporation of electrodes in the receiver, increasing the receiver complexity.
One difficulty in above described non-emissive display is in displaying color images. The field-driven particles of different colors can be provided in discrete color pixels. This approach requires the colored particles to be placed accurately. Moreover, the electrodes that drive the colored particles also need to in precise registration to the color pixels when different color image planes are formed. This approach is therefore complex and expensive.
The field-driven particles of different colors can also be stacked in layers. But since the field-driven particles are usually opaque and scatter light, the color layers under the top color layer normally receives less input light and reflect less corresponding colored light back to the viewers. The lower color layers therefore have low color reflection densities.
An additional problem in the receivers comprising field-driven particles is forming images which are stable. Typically the images on these receivers must be periodically reformed to keep the image from degrading.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a receiver which is highly stable and can be used in an image forming apparatus for producing color images.
A further object of the present invention is to provide a receiver which can produce color images that are highly stable.
These objects are achieved by apparatus for forming an image, comprising:
a) storage means for storing a digitized image;
b) a receiver comprising:
i) a matrix;
ii) a thermomeltable material disposed in the matrix, having a transition temperature range which is above room temperature wherein the viscosity of the thermomeltable material decreases substantially from below to above the transition temperature range; and
iii) field-driven particles, immersed in the thermomeltable material, so that the field-driven particles change reflective densities in response to an applied electric field when the material is above the transition temperature range and is stable at temperatures below its transition temperature range;
c) an array of electrodes associated with the receiver for selectively applying electric fields at an image forming position on the receiver;
d) means for heating the receiver to control the temperature of the receiver to control the response of the field-driven particles in the receiver; and
e) electronic control means coupled to the heater for applying heat to control the temperature of the receiver to selectively control the response of the colored field-driven particles when an electric field is applied and coupled to the electrode array for selectively applying voltages to the electrode array so that electric fields are applied at the image forming position at particular locations on the receiver corresponding to pixels in response to the stored image whereby the electrodes produces a color image in the receiver corresponding to the stored image.
In another aspect of the present invention, the object is achieved by using a receiver for forming images, comprising:
a) a substrate;
b) a layer having a matrix disposed over the substrate and including
i) a thermomeltable material disposed in the matrix, having a transition temperature range which is above room temperature wherein the viscosity of the thermomeltable material decreases substantially from below to above the transition temperature range; and
ii) field-driven particles, immersed in the thermomeltable material, so that the field-driven particles change reflective densities in response to an applied electric field when the material is above the transition temperature range and is stable at temperatures below its transition temperature range.
ADVANTAGES
An advantage of the present invention is that the colored field-driven particles can be provided in a receiver without forming spatially discrete color pixels.
Another advantage of the present invention is that the colored field-driven particles can be addressed in overlapping color pixels so that the spatial resolution is not compromised from monochromatic to color image display having field-driven particles.
A feature of the present invention is that the viscous material surrounding the colored field driven particles are heated to permit fast image writing.
A further feature is to provide a receiver having field-driven particles which is highly stable at room temperature.
An additional advantage is that the image formed by the color field-driven particles on a receiver are stabilized by a viscous material below melting temperature when the image is displayed.
REFERENCES:
patent: 3612758 (1971-10-01), Evans et al.
patent: 4143103 (1979-03-01), Sheridon
patent: 4305807 (1981-12-01), Somlyody
patent: 5344594 (1994-09-01), Sheridon
patent: 5604027 (1997-02-01), Sheridon
patent: 6064410 (2000-05-01), Wen et al.
patent: WO 97/04398 (1997-02-01), None
“A Newly Developed Electrical Twisting Ball Display”, by Saitoh, et al, Proceedings of the SID, vol. 23/4, 1982, pp. 249-253.
Maclean Steven D.
Simpson William H.
Wen Xin
Eastman Kodak Company
Owens Raymond L.
Tran Huan
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