The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 05, 1991
Filed:
Oct. 04, 1989
Ian A Shanks, Penn, GB;
Thorn EMI plc, London, GB;
Abstract
A required visual signal for direct observation is produced from a first source of light in the presence of a second source of light, such as ambient light. Light is transmitted from the first source to a defined surface or defined region distant from the first source. A means for modulating light is operated between at least a first mode and a second mode. This operation is synchronized with a varying of the intensity of at least one of the sources of light at or above a given frequency equal to or greater than the critical fusion frequency for the size and luminance of the required visual signal. When the modulating means is in the first mode, this allows the required visual signal to be directly observed on the defined surface or in the defined region. When the modulating means is in the second mode, this allows the effect produced by any light from the second source incident on the defined surface or in the defined region to be reduced.