Patent US3789420A successfully refreshed from Google Patents.
US3789420A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Wide band recording apparatus
Assignee: Advanced Technology Center Inc
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Filing: 1971-02-02
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Granted: 1974-01-29
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Expires: 1991-02-02
Abstract
Abstract Disclosed is a wide bandwidth recording medium including a thermochromic material which changes reflectance with temperature. Information is recorded on the recording medium by selectively varying temperatures of discrete portions of the thermochromic material with a modulated energy beam such as a laser beam or electron beam. Techniques are described which permit extremely high resolution of data bits to be obtained in the recording medium even though the recording process is a thermal one. Apparatus is also disclosed for erasably and permanently recording information on thermochromic films.
Inventors
- 👤 R Claytor
- 👤 D Eden
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 17:11
CPC Classifications
B; B41; B41M; B41M5/00; B41M5/26; B41M5/28; B41M5/282; B41M5/283; G; G11; G11C; G11C13/00; G11C13/04; G11C13/048
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
264 words
In the class of thermochromic materials that are of the order-disorder type and comprising the ternary halides and the ternary chalcogenide glasses, whose reflectances exhibit hysteresis with change in temperature over a certain range of temperatures, the method of initially achieving different reflectances in different portions of a thermochromic film by subjecting different portions of the film to different heating, temporarily returning the film to a state of substantially uniform reflectance, and subsequently causing the originally obtained diverse reflectances to reappear, comprising the steps of: a. establisHing a first portion of the film at a bias temperature within the hysteresis loop at which it will manifest a certain reflectance, and heating a second portion of the film to a second temperature which is higher than the bias temperature though still within the hysteresis loop, at which it will manifest a reflectance which is different than that of the first portion, whereby a contrast is discernable between the two portions; b. cooling both portions of the film to a temperature at least as low as the maximum saturation temperature associated with the low temperature reflectance of the thermochromic film, whereby the entire film returns to a temporary state of substantially uniform reflectance; and c. thereafter, and within a period of time that is shorter than the relaxation time of the material, uniformly heating all portions of the film to a third temperature which is at least as high as the bias temperature, whereby a contrast in the reflectances of the two portions will again be manifested by virtue of the memory in the thermochromic film.
Claim 2
Dependent Claim
264 words
In the class of thermochromic materials that are of the order-disorder type and comprising the ternary halides and the ternary chalcogenide glasses, whose reflectances exhibit hysteresis with change in temperature over a certain range of temperatures, the method of initially achieving different reflectances in different portions of a thermochromic film by subjecting different portions of the film to different heating, temporarily returning the film to a state of substantially uniform reflectance, and subsequently causing the originally obtained diverse reflectances to reappear, comprising the steps of: a. establisHing a first portion of the film at a bias temperature within the hysteresis loop at which it will manifest a certain reflectance, and heating a second portion of the film to a second temperature which is higher than the bias temperature though still within the hysteresis loop, at which it will manifest a reflectance which is different than that of the first portion, whereby a contrast is discernable between the two portions; b. cooling both portions of the film to a temperature at least as low as the maximum saturation temperature associated with the low temperature reflectance of the thermochromic film, whereby the entire film returns to a temporary state of substantially uniform reflectance; and c. thereafter, and within a period of time that is shorter than the relaxation time of the material, uniformly heating all portions of the film to a third temperature which is at least as high as the bias temperature, whereby a contrast in the reflectances of the two portions will again be manifested by virtue of the memory in the thermochromic film.
Claim 3
Dependent Claim
175 words
With a thermochromic material whose electrical conductivity exhibits hysteresis with change in temperature over a certain range, and whose high temperature state is also its high conductivity state, a method of recording comprising the steps of: a. biasing the thermochromic material at a temperature within its hysteresis loop, whereby its physical state is caused to be particularly sensitive to the addition of heat; b. recording information by shining radiant energy onto certain selected portions of the surface of said thermochromic material and thereby establishing different conductivities in different portions of the material, by virtue of subjecting said certain portions to more heating than other portions which did not absorb the radiant energy, whereby different portions of the material are caused to experience different thermal histories; and c. impressing an electrical potential across the material while it is at a temperature within its hysteresis loop, whereby greater current will flow through those certain portions of the material having higher conductivities and the contrast in reflectance between the radiantly heated portions and the other portions is enhanced.
Claim 4
Dependent Claim
175 words
With a thermochromic material whose electrical conductivity exhibits hysteresis with change in temperature over a certain range, and whose high temperature state is also its high conductivity state, a method of recording comprising the steps of: a. biasing the thermochromic material at a temperature within its hysteresis loop, whereby its physical state is caused to be particularly sensitive to the addition of heat; b. recording information by shining radiant energy onto certain selected portions of the surface of said thermochromic material and thereby establishing different conductivities in different portions of the material, by virtue of subjecting said certain portions to more heating than other portions which did not absorb the radiant energy, whereby different portions of the material are caused to experience different thermal histories; and c. impressing an electrical potential across the material while it is at a temperature within its hysteresis loop, whereby greater current will flow through those certain portions of the material having higher conductivities and the contrast in reflectance between the radiantly heated portions and the other portions is enhanced.
Claim 5
Dependent Claim
61 words
The method of recording set forth in claim 2 wherein the electrical potential is established at a value which causes only enough current to flow through said certain portions so as to heat said portions to a temperature within the hysteresis loop, whereby an original difference in properties manifested by different portions of the material is changed to a greater difference.
Claim 6
Dependent Claim
74 words
The method of recording set forth in claim 2 wherein the electrical potential is established at a value which causes sufficient current to flow through said certain portions so as to heat said certain portions sufficiently beyond the high end of the hysteresis loop in order to achieve a chemical change in said certain portions, whereby an original difference in properties manifested by different portions of the material is permanently set in the material.
Claim 7
Dependent Claim
42 words
The method of recording set forth in claim 2 wherein the different thermal histories are established within a period of time that is not appreciably greater than the ratio of the square of a given diffusion length and the material''s thermal diffusivity.
Claim 8
Dependent Claim
47 words
The method of recording set forth in claim 2 wherein electrical current is caused to flow through portions of the material within a period of time that is not appreciably greater than the ratio of the square of a given diffusion length and the material''s thermal diffusivity.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-01-28 | 1977-07-30 | 1978-01-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-01-28 | 1981-07-30 | 1982-01-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-01-28 | 1985-07-30 | 1986-01-29 | $7700.00 | Window Closed / Lapsed |