# Patent

## Title
Ratio-recording spectrophotometer with suppression of uncompensation

## Abstract

Electrophoretic particles and dispersions are not new per se, and typical examples are given in U.S. Pat. No. 3,668,106. Light colored particles in a dark liquid and dark particles in a light or colorless liquid may be utilized, depending upon the type of display desired. A particle may comprise a metallic oxide pigment or a carbon pigment or titanium oxide coated with a colorless resin to provide the bulk and for controlling the charge. While positively charged particles have been utilized in the preceding discussion, negatively charged particles and neutral particles may also be utilized. Typically the particles are of the order of one micron in diameter and dispersed in the diluent in the ratio of approximately one percent by weight. At the present time, positively charged particles are more readily obtained and controlled. The liquid containing the particles should be relatively dense to help prevent precipitation of the particles. Typical suitable liquids are dibromotetrafluoroethane and di-iodomonofluoromethane. Other standard dispersent liquids such as isopar may be used.

## Background
## Claims

1. In an electronradiograph imaging chamber for providing a visual image, the combination of: therebetween, with said first electrode being relatively transparent optically; positive ion emitter and positioned at the surface of said second electrode facing said first electrode, with X-ray radiation entering said absorber sheet being absorbed and providing electrons and positive ions therein; and attracting electrons toward one electrode and positive ions toward the other depending upon the polarity of the power source and forming an electrostatic charge image, with said particles being selectively deposited at said first electrode as a function of said electrostatic charge image forming a visual image viewable through said first electrode.

2. An imaging chamber as defined in claim 1 wherein said absorber sheet is formed of a photoconductor.

3. An imaging chamber as defined in claim 1 wherein said absorber sheet is formed of at least one of selenium, lead oxide, cadmium sulfide, mercury iodide and cesium iodide.

4. An imaging chamber as defined in claim 1 wherein said absorber sheet comprises a dielectric support with a plurality of spaced passages therethrough, with said passages carrying the absorber material.

5. An imaging chamber as defined in claim 1 wherein said second electrode is relatively transparent optically, and including means for directing light through said electrodes with the deposited particles blocking light transmission.

6. An imaging chamber as defined in claim 1 including means for directing light onto said first electrode with the deposited particles reflecting light.

7. An imaging chamber as defined in claim 1 wherein said first electrode includes a support plate with an electrically conducting layer thereon, and including first means for directing light into said plate from an edge with the deposited particles scattering light.

8. An imaging chamber as defined in claim 7 with said light directed into said plate at an angle to produce substantially total reflection of the light internally of the plate except for that scattered by the deposited particles.

9. An imaging chamber as defined in claim 8 including: deposited particles reflecting light; and means.

10. An imaging chamber as defined in claim 1 wherein said electrophoretic particles are positively charged.

11. An imaging chamber as defined in claim 1 wherein said electrophoretic particles are negatively charged.

12. An imaging chamber as defined in claim 1 wherein said electrophoretic particles are electrically neutral.

13. An imaging chamber as defined in claim 1 including control means for cyclically actuating said imaging chamber to provide real time visual imaging and including means for energizing an X-ray source for a short portion of each cycle and simultaneously energizing an electric power source for attracting electrons and positive ions, and energizing a light source for viewing the deposited particles for a subsequent portion of the cycle.

14. An imaging chamber as defined in claim 13 wherein said control means includes means for connecting a relatively high voltage supply to said electrodes while the X-ray source is energized and then connecting a relatively low voltage supply to said electrodes.

15. An imaging chamber as defined in claim 14 wherein said control means includes means for connecting a voltage supply of reverse polarity prior to energizing the X-ray source.

16. An imaging chamber as defined in claim 13 wherein said control means includes means for connecting a voltage supply of reverse polarity prior to energizing the X-ray source.

17. An imaging chamber as defined in claim 1 including a dielectric layer at the surface of said first electrode facing said second electrode.