# US 8,770,764 B2 · Programmable de-fogger system for a light projector > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,770,764 B2 - Document ID: US8770764B2 - Status: Granted - Kind: B2 - Application number: 13/350,932 - Filed: 2012-01-16 - Published: 2013-07-18 - Granted: 2014-07-08 - Earliest claimed: 2012-01-16 - Assignees: Barco Lighting Systems, Inc. - Applicants: Richard S. Belliveau; David R. Dahly; David Karl Peck - Inventors: Richard S. Belliveau; David R. Dahly; David Karl Peck - Web page: https://patentgrep.com/patent/US8770764B2 ## CPC - G03B 21/16: Cooling; Preventing overheating - F21V 5/04: of lens shape - F21V 29/504: of refractors - F21V 29/60: characterised by the use of a forced flow of gas, e.g. air - F21W 2131/406: for theatres, stages or film studios - G03B 21/10: Projectors with built-in or built-on screen - H04N 9/3141: {Constructional details thereof (details not peculiar to the presence of an electronic spatial light modulator G03B21/14)} - G03B: APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR (optical parts of such apparatus G02B; photosensitive materials or processes for photographic purposes G03C; apparatus for processing exposed photographic materials G03D) - F21V: FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR - F21W: INDEXING SCHEME ASSOCIATED WITH SUBCLASSES F21K, F21L, F21S and F21V, RELATING TO USES OR APPLICATIONS OF LIGHTING DEVICES OR SYSTEMS - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract A light projector for operation during a show that contains theatrical haze. The light projector may include a light source, a lens, a fan, and a housing having an inner chamber. The lens may have a first side and a second side. The first side of the lens may be contained within the inner chamber of the housing. The second side the lens may be outside of the inner chamber of the housing. The fan may be configured to be operated to generate air flow inside the inner chamber of the housing. A substantial portion of the air flow may be directed to impinge upon the first side of the lens to cause de-fogging of theatrical haze condensate on the first side of the lens. ## Claims ### Claim 1 A method comprising generating an air flow inside an inner chamber of a housing of a light projector, so that a substantial portion of the air flow is directed to impinge upon a first side of a lens fixed to the housing to cause de-fogging of theatrical haze condensate on the first side of the lens; and selecting any one of a plurality of de-fogging functions via an operator input panel to cause de-fogging of theatrical haze condensate on the first side of the lens. ### Claim 2 (depends on 1) The method of claim 1 wherein the operator input panel is fixed to the housing. ### Claim 3 (depends on 1) The method of claim 1 wherein the plurality of de-fogging functions include operating a fan to cause de-fogging only when the light projector is not being used to project light from the housing. ### Claim 4 (depends on 1) The method of claim 1 wherein the plurality of de-fogging functions include operating the fan when the light projector is projecting light from the housing. ### Claim 5 (depends on 3) The method of claim 3 wherein the plurality of de-fogging functions include operating the fan when the light projector is projecting light. ### Claim 6 A method comprising generating an air flow inside an inner chamber of a housing of a light projector, so that a substantial portion of the air flow is directed to impinge upon a first side of a lens fixed to the housing to cause de-fogging of theatrical haze condensate on the first side of the lens; receiving de-fogger commands at a communications port fixed to the light projector from an external control device; and causing the received de-fogger commands to be executed by a fan to generate the air flow. ### Claim 7 (depends on 6) The method of claim 6 wherein the external control device is a lighting console. ### Claim 8 (depends on 6) The method of claim 6 wherein the communications port receives de-fogger commands compliant with the DMX protocol. ### Claim 9 (depends on 6) The method of claim 6 wherein the first one of a plurality of de-fogging functions selected by the operator operates the fan to cause de-fogging only when the light projector is not being used to project light. ### Claim 10 A method comprising fixing a light source, and a lens to a housing; fixing a resistive conductor to the housing, in a position with respect to the lens so that the resistive conductor causes de-fogging of theatrical haze condensate on the lens. ### Claim 11 (depends on 10) The method of claim 10 wherein the resistive conductor is applied to the first side of the lens. ### Claim 12 (depends on 10) The method of claim 10 wherein the resistive conductor is a power resistor. ### Claim 13 A method comprising fixing a light source, and a lens to a housing; and fixing an infrared light source, so that the infrared light source projects infrared light onto the lens to cause de-fogging of theatrical haze condensate on the lens. ### Claim 14 (depends on 13) The method of claim 13 wherein the infrared light source projects light to a perimeter of the lens to cause heating of the lens. ### Claim 15 (depends on 13) The light projector of claim 13 wherein the infrared light source is comprised of at least one infrared light emitting diode.