Light box for providing a background illumination having brightness values locally adjusted to the density of a transparency to be viewed by means of the light box

Patent 4637150 Issued on January 20, 1987. Estimated Expiration Date:

May 17, 2005. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.

Abstract Claims Description Full Text

Patent References

1803631

2516270

3249691

3492486

Test plate reader
Patent #: 4003151
Issued on: 01/18/1977
Inventor: Tolosa , et al.

Automatic light intensity control for x-ray film viewer
Patent #: 4118654
Issued on: 10/03/1978
Inventor: Ohta , et al.

Portable map reading system
Patent #: 4164822
Issued on: 08/21/1979
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Patent #: 4267489
Issued on: 05/12/1981
Inventor: Morohashi

Light fixture, light aperture and method of uniformly illuminating an optically diffusive viewing area Patent #: 4335421
Issued on: 06/15/1982
Inventor: Modia , et al.

Inventor

Geluk, Ronald J.

Application

No. 06/735801 filed on 05/17/1985

US Classes:

40/361, PHOTOGRAPHIC TRANSPARENCY VIEWER, E.G., X-RAY VIEWER40/367With internal light source

Examiners

Primary: Mancene, Gene
Assistant: Hakomaki, J.

Attorney, Agent or Firm

Marn; Louis E.

International Class

G02B 27/02 (20060101)

Foreign Application Priority Data

1984-05-18 NL

Abstract

A device for directly viewing an image on a film transparency, in which the illuminating light source is controlled on the basis of discrete information elements written into and stored in a two-dimensional memory during a preliminary image brightness scanning operation. At option, the light beam produced by the light source either has its intensity or its scanning velocity controlled, in order to accordingly vary the brightness level of elementary film surface regions.Velocity modulation is to be preferred as the beam brightness level can then be maintained at an optimally constant value, while the dynamic contrast range of the image viewed by the observer is substantially determined by the beam velocity modulation range.