THERMOMAGNETIC IMAGING METHOD

• US 3,791,843 A
• Filed: 11/03/1971
• Issued: 02/12/1974
• Est. Priority Date: 11/04/1970
• Status: Expired due to Term

• Current Assignee: Josef Kohlmannsperger
• Original Assignee: Josef Kohlmannsperger
• Inventors: Kohlmannsperger, Josef
• Primary Examiner(s): Martin, William D.
• Assistant Examiner(s): Sofocleous, M.
• Application Number:
  US05/195,338
• Time in Patent Office: 832 Days
• Field of Search: 117/237,240,17.5 346/1,74MT 250/65T
• US Class Current: 430/123.4
• CPC Class Codes: G03G 19/00 Processes using magnetic patterns; Apparatus therefor , i.e. magnetography
• CPC Class Codes: Y10S 101/37 Printing employing electrostatic force

Abstract

The magentic image receiving surface of a copying apparatus is provided with a layer of FeRh or an analogous ingredient which is antiferromagnetic above and below its Neel temperature but exhibits a pronounced coercive force at the Neel temperature. The image receiving surface is moved past an exposure station to receive a thermal image of an original. The exposing step may involve heating selected areas of the image receiving surface to Neel temperature in accordance with the image pattern of the original or heating selected areas of the image receiving surface to above the Neel temperature while the remaining areas remain at Neel temperature. The resulting thermal image is converted with magnetic toner into a powder image, either on the image receiving surface or upon transfer onto an auxiliary surface, and the powder image is transferred onto and fused to paper or another transfer material.

Claims

2. A method as defined in claim 1, wherein said ingredient is FeRh.

3. A method as defined in claim 1, further comprising the step of maintaining said ingredient below said Neel temperature prior to said exposing step, said temperature changing step comprising heating said first areas of said surface to said Neel temperature and said other temperature being substantially below said Neel temperature.

4. A method as defined in claim 1, further comprising the step of maintaining said ingredient at said Neel temperature prior to said exposing step, said temperature changing step comprising heating said second areas above said Neel temperature so that said other temperature substantially exceeds said Neel temperature.

5. A method as defined in claim 1, further comprising the step of maintaining said ingredient prior to said exposing step at a temperature which closely approximates the temperature of one of said first and second areas upon completion of said temperature changing step.

6. A method as defined in claim 1, further comprising the step of transferring said powder image onto a transfer material.

7. A method as defined in claim 1, wherein said contacting step comprises contacting the exposed image receiving surface with a coat of pulverulent magnetic toner carried on a donor surface from which said coat the image receiving surface removes toner so that the thus removed toner adheres to said first area of said image receiving surface and the remainder of said coat conStitutes said powder image.

8. A method as defined in claim 1, further comprising the step of transferring said thermal image of said image recieving surface onto a magnetic layer whose coercive force is less than the coercive force of said ingredient at said Neel temperature, said contacting step comprising placing said transferred thermal image at least once into contact with a pulverulent magnetic toner to thus convert said thermal image into a powder image.

9. A method as defined in claim 1, wherein said toner consists of pigmentized thermoplastic material and magnetizable carrier for said pigmentized thermoplastic material.

10. A method as defined in claim 9, further comprising the steps of transferring said powder image onto a transfer material and fixing the transferred powder image to the transfer material in the presence of heat.