Variable color-output strobe for photographic apparatus

• US 5,109,248 A
• Filed: 09/21/1990
• Issued: 04/28/1992
• Est. Priority Date: 12/27/1988
• Status: Expired due to Fees

• Current Assignee: Senshin Capital LLC (Intellectual Ventures LLC)
• Original Assignee: Polaroid Corporation (PLR IP Holdings LLC)
• Inventors: Petrakos, Stephanie, Gaewsky, John P.
• Primary Examiner(s): ADAMS JR, RUSSELL E
• Application Number:
  US07/586,512
• Time in Patent Office: 585 Days
• Field of Search: 354/413, 354/132, 354/21, 354/430, 315/358
• US Class Current: 396/155
• CPC Class Codes: H01J 61/95 Lamps with control electrode for varying intensity or wavelength of the light, e.g. for producing modulated light
• CPC Class Codes: H05B 41/325 by measuring the incident light

Abstract

A single flash discharge tube system is provided that is capable of emitting artificial light of a controlled and variable spectral output to compensate for photographic film color variations and/or extremes in scene color temperature. The flash tube contains a mixture of two or more gasses with each gas in the tube having a different ionization potential. When ionized, each gas or combination thereof produces light having a different spectral output. The ionization of each gas is controlled by a trigger voltage applied to the flash tube in accordance with a code on a film container indicative of the color balance of film contained therein and/or sensing apparatus that determines scene color temperature.

Claims

1. A flash discharge device for illuminating a scene to be photographically exposed, comprising:

an airtight housing through which light may be transmitted toward the scene to be photographically exposed, for enclosing a gaseous mixture;

a mixture of gases contained within said housing, with at least two of the gasses forming said mixture having different ionization potentials;

means for generating at least two electrical potentials with each such electrical potential having a different potential magnitude; and

means responsive to a signal representative of the scene color temperature and/or a signal representative of the color balance of a photosensitive material being used to record the scene for selectively coupling one of said electrical potentials to said gas mixture to ionize one of the gases included therein without ionizing another and thereby generate a source of light having a particular spectral content and subsequently transmit said light outwardly of said airtight housing and toward the scene to be photographed.

2. The flash discharge device of claim 1 wherein said selective coupling means includes a single gas-ionizing electrode and each of said gas ionizing output potentials are selectively coupled to said enclosed gas mixture through said single gas-ionizing electrode.

3. The flash discharge device of claim 1 wherein said selective coupling means includes a number of different gas-ionizing electrodes equal to the number of gases forming said gas mixture with each such electrode selectively coupling a single ionization potential thereto.

4. Photographic apparatus adapted to receive a film cassette having indicia thereon representative of the color balance of photosensitive material contained therein, and including a flash discharge device for providing artificial illumination during an exposure cycle, said photographic apparatus comprising;

a housing;

an airtight enclosure mounted on said housing, through which light maybe transmitted toward a scene to be photographically exposed;

a mixture of gases contained within said enclosure, with at least two of the gases forming said mixture having different ionization potentials;

means for generating at least two electrical potentials with each such electrical potential having a different potential magnitude;

means for generating a signal representative of the scene color temperature;

means responsive to the color balance information encoded in the film cassette indicia for generating a signal representative thereof;

means for initiating a photographic exposure cycle; and

means responsive to said scene color temperature signal and/or said color balance signal for selectively coupling one of said electrical potentials to said gas mixture to ionize one of the gases included therein without ionizing another to thereby generate a source of light having a particular spectral content and thereby transmit said light toward the scene to be photographed during an exposure cycle.

5. The photographic apparatus of claim 4 wherein said selective coupling means time modulates the coupling of said output potentials to said gas mixture.