# US 8,770,807 B2 · Method and device for increasing the robustness of a vehicle headlight having a cylindrical prism > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,770,807 B2 - Document ID: US8770807B2 - Status: Granted - Kind: B2 - Application number: 13/642,586 - Filed: 2011-04-13 - Published: 2013-02-07 - Granted: 2014-07-08 - Earliest claimed: 2010-04-21 - Assignees: Continental Automotive GmbH - Applicants: Stefan Holzinger - Inventors: Stefan Holzinger - Web page: https://patentgrep.com/patent/US8770807B2 ## CPC - G01D 5/24457: {Failure detection} - F21S 41/635: {by moving refractors, filters or transparent cover plates} - F21S 41/698: Shaft-shaped screens rotating along its longitudinal axis - G01D 5/142: {using Hall-effect devices (measuring magnetic variables using Hall-effect or other galvanomagnetic devices G01R33/06)} - G01D: MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR - F21S: NON-PORTABLE LIGHTING DEVICES; SYSTEMS THEREOF; VEHICLE LIGHTING DEVICES SPECIALLY ADAPTED FOR VEHICLE EXTERIORS ## Abstract A method is provided for increasing the robustness of a vehicle headlight comprising a cylindrical prism that can rotate about a rotary axis in a plurality of rotary positions and comprising a Hall effect sensor by means of the output signals of which the rotary position of the cylindrical prism can be determined. According to the method, a check is made as to whether a defect of the Hall effect sensor is present. In the event of a defect of the Hall effect sensor, a stop is temporarily provided and the rotary position of the prism is verified by being blocked at the provided stop. ## Claims ### Claim 1 A method for increasing the robustness of a vehicle headlight having a cylindrical prism that is rotatable about a rotary axis using a first drive, and a Hall sensor that generates output signals for determining a rotary position of the cylindrical prism, the method comprising: performing a check to identify a defect of the Hall sensor, in response to identifying a defect of the Hall sensor: automatically moving the prism to a predefined stop position in which a movement of the prism is blocked by a physical stop, and automatically moving the prism from the predefined stop position to another predefined position. ### Claim 2 (depends on 1) The method of claim 1, wherein automatically moving the prism from the predefined stop position to another predefined position comprises rotating the prism to a predefined rotary position relative to the stop position. ### Claim 3 (depends on 1) The method of claim 1, wherein moving the prism to the predefined stop position includes moving the prism with a second drive. ### Claim 4 (depends on 3) The method of claim 3, wherein the second drive provides an axial displacement of the prism. ### Claim 5 (depends on 1) The method of claim 1, wherein moving the cylindrical prism to the predefined stop position includes an axial displacement and a subsequent rotation of the cylindrical prism. ### Claim 6 (depends on 5) The method of claim 5, wherein the predefined stop position for the prism is provided at an end stop of the second drive. ### Claim 7 (depends on 6) The method of claim 6, wherein the subsequent rotation of the cylindrical prism comprises rotating the prism until a stop element provided on the cylindrical prism contacts a stop counter element of the end stop. ### Claim 8 (depends on 1) The method of claim 1, wherein the check to identify the defect of the Hall sensor is performed in connection with a reference run. ### Claim 9 An apparatus for increasing the robustness of a vehicle headlight, comprising: a cylindrical prism rotatable about a rotary axis to a plurality of rotary positions using a first drive, and a Hall sensor that generates output signals for determining a rotary position of the cylindrical prism, a control unit configured to: perform a check to identify a defect of the Hall sensor is present, and in response to identifying a defect of the Hall sensor: automatically move the prism to a predefined stop position in which a movement of the prism is blocked by a physical stop, and automatically move the prism from the predefined stop position to another predefined position. ### Claim 10 (depends on 9) The apparatus of claim 9, comprising a second drive configured to move the prism toward the predefined stop position. ### Claim 11 (depends on 9) The apparatus of claim 9, wherein automatically moving the prism from the predefined stop position to another predefined position comprises rotating the prism to a predefined rotary position relative to the stop position. ### Claim 12 (depends on 10) The apparatus of claim 10, wherein the second drive provides an axial displacement of the prism. ### Claim 13 (depends on 9) The apparatus of claim 9, wherein a stop element is provided at the cylindrical prism and a stop counter element is provided at an end stop of the motor-vehicle headlight, and wherein moving the cylindrical prism to the predefined stop position includes an axial displacement, and a subsequent rotation of the cylindrical prism until a stop element provided on the cylindrical prism contacts a stop counter element of the end stop.