Binary logic apparatus

Claim 3

The method set forth in claim 1 wherein said discrete portions are heated by Joule heating to a third temperature which is greater than said second temperature but less than the minimum saturation temperature associated with the high temperature reflectance of said thermochromic film.

Claim 4

The method set forth in claim 1 wherein said discrete portions are heated to a third temperature which is substantially greater than the minimum saturation temperature associated with the high temperature reflectance of said thermochromic film, thereby to cause permanent change in the reflectance of said discrete portions.

Claim 5

In an apparatus for recording high resolution binary data at selected spots on an erasable, re-usable recording medium, which apparatus includes means for producing radiation signals in binary form, said means including a source of radiation and means for focusing the radiation to a beam having a diameter appreciably less than 30 microns, said apparatus further including an erasable, reusable recording medium which incorporates a thermochromic material having a detectable characteristic which exhibits hysteresis with change in temperature over a certain range, said thermochromic material having a hysteresis loop bounded on its high end by a minimum saturation temperature associated with its high temperature characteristic and on its low end by a maximum saturation temperature associated with its low temperature characteristic, and said recording medium having a thermal time constant defined as the ratio of the square of a given thermal diffusion length occasioned by absorbed energy passing laterally through the material and the material''s thermal diffusivity, said recording medium being characterized by recording the incidence of radiation signals without vaporizing as a result of such incidence, and said recording medium having a surface with a multiplicity of discrete portions with each having a unique address, the method of: a. establishing a bias temperature in said thermochromic material between said minimum saturation temperature and said maximum saturation temperature; and b. directing said radiation signals onto selected ones of the discrete portions of the surface of said thermochromic material in order to directly heat said portions, said discrete portions having a size which is the same as the beam diameter, thereby to temporarily raise the temperature of somewhat larger portions of said thermochromic material to a recording temperature which is greater than said bias temperature, said larger portions encompassing the directly heated portions, and said radiation signals being directed onto said material within a controlled period of time that is sufficiently short so that diffusion of heat is limited to the extent that said larger portions of heated material have a maximum dimension of 30 microns, with the controlled period of time being not appreciably greater than the recording medium''s thermal time constant, and the diffusion of heat being limited so that heat from a surface portion at one address does not diffuse into a surface portion at an adjacent address, whereby the subsequent interrogation of said recording medium will not provide an erroneous answer because of uncontrolled heat diffusion through the material.

Claim 6

In an apparatus for recording high resolution binary data at selected spots on an erasable, re-usable recording medium, which apparatus includes means for producing radiation signals in binary form, said means including a source of radiation and means for focusing the radiation to a beam having a diameter appreciably less than 30 microns, said apparatus further including an erasable, reusable recording medium which incorporates a thermochromic material having a detectable characteristic which exhibits hysteresis with change in temperature over a certain range, said thermochromic material having a hysteresis loop bounded on its high end by a minimum saturation temperature associated with its high temperature characteristic and on its low end by a maximum saturation temperature associated with its low temperature characteristic, and said recording medium having a thermal time constant defined as the ratio of the square of a given thermal diffusion length occasioned by absorbed energy passing laterally through the material and the material''s thermal diffusivity, said recording medium being characterized by recording the incidence of radiation signals without vaporizing as a result of such incidence, and said recording medium having a surface with a multiplicity of discrete portions with each having a unique address, the method of: a. establishing a bias temperature in said thermochromic material between said minimum saturation temperature and said maximum saturation temperature; and b. directing said radiation signals onto selected ones of the discrete portions of the surface of said thermochromic material in order to directly heat said portions, said discrete portions having a size which is the same as the beam diameter, thereby to temporarily raise the temperature of somewhat larger portions of said thermochromic material to a recording temperature which is greater than said bias temperature, said larger portions encompassing the directly heated portions, and said radiation signals being directed onto said material within a controlled period of time that is sufficiently short so that diffusion of heat is limited to the extent that said larger portions of heated material have a maximum dimension of 30 microns, with the controlled period of time being not appreciably greater than the recording medium''s thermal time constant, and the diffusion of heat being limited so that heat from a surface portion at one address does not diffuse into a surface portion at an adjacent address, whereby the subsequent interrogation of said recording medium will not provide an erroneous answer because of uncontrolled heat diffusion through the material.

Claim 7

The method defined in claim 4 wherein said thermochromic material is disposed between electrically conductive members during the time that said radiation signals may be directed onto discrete portions, and including the step of passing current simultaneously between said conductive members and through said thermochromic material, whereby the contrast between the discrete portions and the rest of the material is enhanced.

Claim 8

In an apparatus having an erasable recording means including a thermochromic film which exhibits hysteresis in changing from a first reflectance to a second reflectance with changing temperature over a certain range, said thermochromic film having a hysteresis loop bounded on its high end by a minimum saturation temperature associated with its high temperature reflectance and on its low end by a maximum saturation temperature associated with its low temperature reflectance, and said thermochromic film having a multiplicity of addressed portions at which information bits are to be recorded, the method comprising the steps of: a. establishing a bias temperature in said thermochromic film between said minimum and maximum saturation temperature, thereby to cause said film to exhibit a first reflectance, with the bias temperature being selected near the middle of the hysteresis loop so as to promote an appreciable change in the film''s reflectance with only a small change in temperature; b. producing radiant energy in pulses corresponding to binary information bits which are to be recorded; c. directing a first pulse of radiant energy of a given magnitude onto a selected discrete portion of said thermochromic film, thereby to temporarily raise the temperature of said discrete portion to a second temperature which is greater than said bias temperature so as to change the reflectance of said discrete portion to a second reflectance; d. re-establishing thermal equilibrium in the thermochromic film after termination of each pulse; and e. directing another pulse of radiant energy of a second magnitude onto selected ones of said discrete portions, with the magnitude of the second pulse being greater than that of the first pulse, said second pulse of radiant energy being sufficient to raise the temperature of said discrete portion to a third temperature which is greater than said bias temperature, thereby to invert the reflectance of the discrete portion from said second reflectance back to said first reflectance.

Claim 9

In an apparatus having an erasable recording means including a thermochromic film which exhibits hysteresis in changing from a first reflectance to a second reflectance with changing temperature over a certain range, said thermochromic film having a hysteresis loop bounded on its high end by a minimum saturation temperature associated with its high temperature reflectance and on its low end by a maximum saturation temperature associated with its low temperature reflectance, and said thermochromic film having a multiplicity of addressed portions at which information bits are to be recorded, the method comprising the steps of: a. establishing a bias temperature in said thermochromic film between said minimum and maximum saturation temperature, thereby to cause said film to exhibit a first reflectance, with the bias temperature being selected near the middle of the hysteresis loop so as to promote an appreciable change in the film''s reflectance with only a small change in temperature; b. producing radiant energy in pulses corresponding to binary information bits which are to be recorded; c. directing a first pulse of radiant energy of a given magnitude onto a selected discrete portion of said thermochromic film, thereby to temporarily raise the temperature of said discrete portion to a second temperature which is greater than said bias temperature so as to change the reflectance of said discrete portion to a second reflectance; d. re-establishing thermal equilibrium in the thermochromic film after termination of each pulse; and e. directing another pulse of radiant energy of a second magnitude onto selected ones of said discrete portions, with the magnitude of the second pulse being greater than that of the first pulse, said second pulse of radiant energy being sufficient to raise the temperature of said discrete portion to a third temperature which is greater than said bias temperature, thereby to invert the reflectance of the discrete portion from said second reflectance back to said first reflectance.

Claim 10

The method defined in claim 4 wherein said thermochromic material consists essentially of material selected from the group consisting of: a. material having the general formula M2M''X4 where M is Ag1 , Cu1 , or Tl1 , M'' is Hg2 or Cd2 , and X is a halide; b. material having the general formula MM''2X4 where M is zinc, cadmium or mercury, M'' is aluminum, gallium or indium, and X is sulphur, selenium or tellurium; and c. the vanadium oxides.

Claim 11

Apparatus for recording high resolution binary data on an erasable, re-usable recording medium, comprising: a. means for producing radiation signals in binary form, said means including a source of radiation and means for focusing the radiation to a beam having a diameter appreciably less than 30 microns; b. an erasable, re-usable recording medium including a thermochromic material having at least one detectable characteristic including reflectance which exhibits hysteresis with change in temperature over a certain range, said thermochromic material having a hysteresis loop bounded by a minimum saturation temperature associated with its high temperature characteristic and a maximum saturation temperature associated with its low temperature characteristic, and said thermochromic material being disposed between electrically conductive members, and including means for passing current simultaneously between said conductive Members and through said thermochromic material; c. means for establishing a bias temperature in said thermochromic material between said minimum saturation temperature and said maximum saturation temperature, whereby the material can be made particularly sensitive to incident radiation; d. means for directing said radiation signals onto discrete portions of the surface of said thermochromic material in order to directly heat said portions, said discrete portions having a size which is the same as the beam size, thereby to temporarily raise the temperature of somewhat larger portions of said thermochromic material to a recording temperature which is greater than said bias temperature, said larger portions encompassing the directly heated portions and resulting from the diffusion of heat from the directly heated portions, said means being adapted to direct said radiation signals onto said material within a controlled period of time that is sufficiently short so that thermal diffusion is limited to the extent that said larger portions of heated material have a maximum dimension of 30 microns; e. means for scanning said thermochromic material with an electron beam which imparts substantially less energy per unit area to said thermochromic material than said radiation signals; and f. means for detecting the current passing through the thermochromic material when said material is scanned by the scanning beam.

Claim 12

Apparatus for recording high resolution binary data on an erasable, re-usable recording medium, comprising: a. means for producing radiation signals in binary form, said means including a source of radiation and means for focusing the radiation to a beam having a diameter appreciably less than 30 microns; b. an erasable, re-usable recording medium including a thermochromic material having at least one detectable characteristic including reflectance which exhibits hysteresis with change in temperature over a certain range, said thermochromic material having a hysteresis loop bounded by a minimum saturation temperature associated with its high temperature characteristic and a maximum saturation temperature associated with its low temperature characteristic, and said thermochromic material being disposed between electrically conductive members, and including means for passing current simultaneously between said conductive Members and through said thermochromic material; c. means for establishing a bias temperature in said thermochromic material between said minimum saturation temperature and said maximum saturation temperature, whereby the material can be made particularly sensitive to incident radiation; d. means for directing said radiation signals onto discrete portions of the surface of said thermochromic material in order to directly heat said portions, said discrete portions having a size which is the same as the beam size, thereby to temporarily raise the temperature of somewhat larger portions of said thermochromic material to a recording temperature which is greater than said bias temperature, said larger portions encompassing the directly heated portions and resulting from the diffusion of heat from the directly heated portions, said means being adapted to direct said radiation signals onto said material within a controlled period of time that is sufficiently short so that thermal diffusion is limited to the extent that said larger portions of heated material have a maximum dimension of 30 microns; e. means for scanning said thermochromic material with an electron beam which imparts substantially less energy per unit area to said thermochromic material than said radiation signals; and f. means for detecting the current passing through the thermochromic material when said material is scanned by the scanning beam.