BLACK-AND-WHITE IMAGE CONTROL BY ULTRASONIC MODULATION OF NEMATIC LIQUID CRYSTALS

• US 3,700,805 A
• Filed: 08/26/1971
• Issued: 10/24/1972
• Est. Priority Date: 08/26/1971
• Status: Expired due to Term

• Current Assignee: Thomas F. Hanlon
• Original Assignee: Thomas F. Hanlon
• Inventors: Hanlon, Thomas F.
• Primary Examiner(s): Griffin, Robert L.
• Assistant Examiner(s): Stout, Donald E.
• Application Number:
  US05/175,395
• Time in Patent Office: 425 Days
• Field of Search: 250/199 178/7.3D,7.5D,5.4BD 350/16LC,161 332/7.51 23/23LC
• US Class Current: 348/198
• CPC Class Codes: G02F 1/11 based on acousto-optical elements, e.g. using variable diffraction by sound or like mechanical waves acousto-optical deflection G02F1/33
• CPC Class Codes: G02F 1/13 based on liquid crystals, e.g. single liquid crystal display cells

Abstract

A modulator in which ultrasonic waves are generated by a video carrier potential applied to a piezoelectric transducer mounted in a glass-sided cell containing a nematic liquid crystal, is positioned in the path of light from a source consisting of a stroboscopically pulsed (at the rate of the speed of sound) visible light laser or non-coherent light source, to produce a complete black-and-white television image.

Claims

1. An ultrasonic modulator comprising:

a container having opposed transparent sides and ends bounding an inner cavity, a nematic liquid crystal disposed in said cavity, a piezoelectric transducer mounted in said cavity adjacent one of said ends of said container for imparting ultrasonic waves to said nematic crystal, an attenuator disposed in said cavity at the opposite end of said container, and means for applying high frequency video signals to said transducer so as to generate ultrasonic waves in said nematic crystal.

2. A modulator as in claim 1 further including a light source positioned with respect to said container so that light from said source passes through said transparent sides and is varied in density in accordance with said video signals.

3. A modulator as in claim 2 further including means for stroboscopicallly pulsing said light source at the speed of sound.

4. A modulator as in claim 3 wherein said light source is a laser.

5. A modulator as in claim 3 including light reflective means mounted for receiving the light which has passed through the transparent sides of said container and directing that light so as to produce a video line scan.

6. For use in electronic imaging systems, an ultrasonic modulator consisting of a container having opposed transparent sides, a piezoelectric transducer mounted therein spaced from one end thereof and having its opposed faces facing opposite ends of the container, the container having an attenuator mounted in said one end thereof, and a nematic liquid crystal filling the container between said attenuator and said transducer, the modulator positioned with respect to a light source so that the light passes through said transparent sides, a source of received high frequency video potential, means for applying said received high frequency video potentials to said piezoelectric transducer whereby said potentials generating modulated ultrasonic waveS in said nematic liquid crystal thereby altering the molecular structure thereof so that light from said source varies in black-and-white density in accordance with the black-and-white density information conveyed by said potentials.

7. An imaging system for producing a complete black-and-white television image including an ultrasonic modulator consisting of a container having opposed transparent sides, a piezoelectric transducer mounted therein spaced from one end thereof and having its opposed faces facing opposite ends of the container, the container having an attenuator mounted in said one end thereof, and a nematic liquid crystal filling the container between said attenuator and said transducer, a light source stroboscopically pulsed at the speed of sound, the modulator being so positioned that light from said source passes through said transparent sides of the container, a source of received high frequency video carrier potential, the transducer having the received high frequency video carrier potential applied to said faces thereof thereby producing ultrasonic waves in said liquid crystal traveling from said transducer toward said attenuator consequently producing light scattering and density centers in the ordered molecular structure of said liquid crystal, said pulsed light source bringing said modulated beam of light to a stop thereby producing across the container all the video information in said video signal in a horizontal line, and a galvanometer synchronized with a video vertical sync signal for vertically modulating the horizontal video image thereby producing a complete black-and-white television image adapted to be projected on to a screen.

8. An imaging system according to claim 7, wherein said pulsed light source is a visible light laser.

9. An imaging system according to claim 7, wherein said pulsed light source is a noncoherent light source.