WO2006056577A1 - Rectification de distorsion trapezoidale dans des systemes de projection laser - Google Patents

Rectification de distorsion trapezoidale dans des systemes de projection laser Download PDF

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Publication number
WO2006056577A1
WO2006056577A1 PCT/EP2005/056171 EP2005056171W WO2006056577A1 WO 2006056577 A1 WO2006056577 A1 WO 2006056577A1 EP 2005056171 W EP2005056171 W EP 2005056171W WO 2006056577 A1 WO2006056577 A1 WO 2006056577A1
Authority
WO
WIPO (PCT)
Prior art keywords
distortion
line
projection
laser
projection systems
Prior art date
Application number
PCT/EP2005/056171
Other languages
German (de)
English (en)
Inventor
Christian Gammer
Ralf Hying
Original Assignee
Benq Mobile Gmbh & Co. Ohg
Benq Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Benq Mobile Gmbh & Co. Ohg, Benq Corporation filed Critical Benq Mobile Gmbh & Co. Ohg
Publication of WO2006056577A1 publication Critical patent/WO2006056577A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/12—Picture reproducers
    • H04N9/31—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
    • H04N9/3129—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM] scanning a light beam on the display screen
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/0025—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for optical correction, e.g. distorsion, aberration
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/12—Picture reproducers
    • H04N9/31—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
    • H04N9/3179—Video signal processing therefor
    • H04N9/3185—Geometric adjustment, e.g. keystone or convergence

Definitions

  • the invention relates to a method according to the preamble of patent claim 1.
  • miniaturization of projection devices for their use in interaction with mobile telephones can be a way out of this contrast.
  • a promising design of mini projectors is the projection with the aid of a laser beam deflected via a 2D micromirror.
  • the laser beam scans the projection surface line by line, similar to the electron beam in a cathode ray tube.
  • An image is created by modulating the image data onto the laser beam.
  • a problem in the projection with mobile projection systems is that the angle between the projection direction, or between the center beam of the projection beam, and the normal of the projection surface can change during the projection. If this angle is not zero, image distortions occur, the so-called trapezoidal distortion or keystone distortion.
  • the invention has for its object to provide a method for electronic equalization of the keystone distortion. This object is achieved by the features specified in patent claim 1 features.
  • the compensation of the keystone distortion by means of a counter-distortion of the image content.
  • This counterdistraction occurs in particular by a real-time adaptation of the laser modulation.
  • Figure 1 is a basic concept of the method according to the invention
  • Figure 2 is a schematic diagram for carrying out the inventive method
  • FIGS 3 and 4 an application of the method according to the invention.
  • the method according to the invention compensates for the trapezoidal drawing in that the image content is, so to speak, counter-distorted before the projection on electronic paths.
  • the trapezoidal distortion resulting from the optical path is, for example, influenced by an oblique angle of incidence of the projection beam onto a projection surface, compensated by an electronically generated opposite distortion or distortion.
  • an at least almost distortion-free projection image with parallel edges is formed as desired.
  • the optical keystone distortion produces a comparatively wider image line at the upper edge of the image than at the lower edge.
  • Such a distortion is caused, for example, by se by an obliquely upwardly directed projector on ei ⁇ nem table.
  • the orientation between the projection axis and the projection surface is to be determined.
  • methods for example via inclination sensors, or methods based on distance measurements. These methods are not the subject of the invention and are therefore not described in detail.
  • the counter-distortion of the image content takes place by adaptation of the laser modulation.
  • the pixels at the upper edge of the image are slightly compressed, for example by an algorithm, during the projection of a line. This results in narrower lines at the upper edge of the image projection and wider lines at the lower edge. This is done, as already stated in the principle description, in opposite relationship to the existing or on optical way resulting keystone distortion.
  • the maximum line length in the example shown is the length of the line at the bottom of the screen.
  • the line length t z thus also changes.
  • the length of the delay time t D is linearly reduced from its maximum value in the uppermost row, for example, down to the value zero in the last row.
  • the last, lowest line is a - largely - undistorted displayed line.
  • the laser remains dark, ie no pixels are displayed on the projection surface.
  • the delay time t D will increase from a value of zero to its maximum value or extreme value.
  • the number of pixels per line is preferably constant throughout the image.
  • the method according to the invention can be used in all laser projection devices in which the projection beam is deflected via micromirrors.
  • One of the advantages is that no additional mechanical or optical components are needed, but only the activation of the laser is expanded.
  • the method can be implemented, for example, as an electronic circuit, FPGA (ASIC) module or as software in a microcontroller or DSP.
  • ASIC electronic circuit
  • FIG 3 the method is illustrated by the example of a built-in a pen projection system. The details are the figure removed.
  • the projection is designed in this example to an angle ⁇ of preferably 60 degrees between pin axis and projection surface. If, during use of the pen, this angle is changed by the hand position of the user, this change can be detected, for example, via an inclination sensor and corrected in real time by the method according to the invention.
  • the method according to the invention is basically not only suitable for compensating a trapezoidal distortion in one direction, but can also compensate for distortions that arise due to the inclination of the projection unit in several directions or due to rotation.

Abstract

La présente invention concerne un procédé pour réaliser la rectification électronique de distorsions trapézoïdales dans des systèmes de projection laser, en particulier des systèmes de projection laser mobiles. Selon l'invention, une distorsion trapézoïdale survenant sur la trajectoire optique, est compensée par une distorsion opposée produite sur la trajectoire électronique, ou une distorsion du contenu d'image, la superposition des deux distorsions permettant l'obtention d'une image de projection au moins approximativement dépourvue de distorsion, présentant des arêtes parallèles.
PCT/EP2005/056171 2004-11-24 2005-11-23 Rectification de distorsion trapezoidale dans des systemes de projection laser WO2006056577A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102004056753 2004-11-24
DE102004056753.0 2004-11-24

Publications (1)

Publication Number Publication Date
WO2006056577A1 true WO2006056577A1 (fr) 2006-06-01

Family

ID=35840499

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2005/056171 WO2006056577A1 (fr) 2004-11-24 2005-11-23 Rectification de distorsion trapezoidale dans des systemes de projection laser

Country Status (1)

Country Link
WO (1) WO2006056577A1 (fr)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5465121A (en) * 1993-03-31 1995-11-07 International Business Machines Corporation Method and system for compensating for image distortion caused by off-axis image projection
EP0773679A2 (fr) * 1995-11-13 1997-05-14 Daewoo Electronics Co., Ltd Procédé pour précompenser une image asymétrique dans un système de projection d'image
US6191827B1 (en) * 1998-12-01 2001-02-20 Oplus Technologies Ltd. Electronic keystone correction for electronic devices with a visual display
US6493044B1 (en) * 1998-06-01 2002-12-10 Mustek Systems Inc. Digital keystone modulation circuit
US20040036844A1 (en) * 2002-06-12 2004-02-26 Wood John S. Automatic keystone correction system and method

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5465121A (en) * 1993-03-31 1995-11-07 International Business Machines Corporation Method and system for compensating for image distortion caused by off-axis image projection
EP0773679A2 (fr) * 1995-11-13 1997-05-14 Daewoo Electronics Co., Ltd Procédé pour précompenser une image asymétrique dans un système de projection d'image
US6493044B1 (en) * 1998-06-01 2002-12-10 Mustek Systems Inc. Digital keystone modulation circuit
US6191827B1 (en) * 1998-12-01 2001-02-20 Oplus Technologies Ltd. Electronic keystone correction for electronic devices with a visual display
US20040036844A1 (en) * 2002-06-12 2004-02-26 Wood John S. Automatic keystone correction system and method

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