Deflection device for a projection apparatus, projection apparatus for projecting an image and method for controlling a deflection apparatus for a projection apparatus

US9151949B2 · kind B2 · utility

Assignee

• Fraunhofer-Gesellschaft zur förderung der angewandten Forschung e.V. · DE

Inventors

• Ulrich Hofmann · Itzehoe, DE
• Lars Ratzmann · Osterhofen, DE
• Joachim Janes · Itzehoe, DE
• Manfred Weiss · Bad Liebenzell, DE
• Sascha Mühlmann · Itzehoe, DE

Key dates

• Filing date: Dec 13, 2010
• Grant date: Oct 6, 2015
• Expiry date: Nov 7, 2032

Classification

• Technology area (CPC H): Electricity
• CPC primary: H04N9/3135
• WIPO field: Audio-visual technology
• WIPO sector: Electrical engineering

Abstract

The invention relates to a deflection device for a projection apparatus for projecting Lissajous figures onto an observation field which is made to deflect a light beam about at least one first and one second deflection axis for generating Lissajous figures having a deflection unit for producing oscillations about the deflection axes and having a control apparatus for producing control signals for the deflection unit having a first and second control frequency which substantially corresponds to the resonant frequencies of the deflection unit, wherein the deflection unit has a quality factor of >3,000 and the control apparatus includes a feedback loop which is configured to regulate the first and/or second control frequencies in dependence on a measured phasing of the oscillations of the deflection unit so that the maximum amplitude of the oscillations remains in the resonant range of the deflection unit. The invention further relates to a projection apparatus having such a deflection device as well as to a method for controlling a corresponding deflection device.