Optics: eye examining – vision testing and correcting – Eye examining or testing instrument – Objective type
Reexamination Certificate
2000-03-31
2001-05-15
Manuel, George (Department: 3737)
Optics: eye examining, vision testing and correcting
Eye examining or testing instrument
Objective type
Reexamination Certificate
active
06231185
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a method for operating an apparatus for acquiring the location of at least one characteristic area of a person and for generating a control signal for a device dependent on this location.
2. Description of the Related Art
German Patent DE 27 40 908 discloses an x-ray diagnostics means for transillumination and provides a means for acquiring the viewing direction of an observer. The means is connected to a control device for varying the direction of the central ray of a ray beam emanating from an x-ray source, so that the direction of the central ray can be modified dependent on the viewing direction of the observer.
The periodical Bild der Wissenschaft, Nr. 3, 1977, page 27, published a report under the title “Blick ins Auge” according to which scientists of the Radiation Center of Honeywell (Lexington/USA) have developed a device that makes it possible to acquire, to register and to visualize the viewing direction of a test person as preciseley as possible. An infrared light beam is directed onto the eyes of the test person and a special video camera registers each eye movement. The information identified in this way are supplied to a mini-computer that calculates the respective position of where the person is looking and allows this to appear on a picture screen as a visible point. The scene observed by the test person can be seen on the same picture screen. The “remote oculometer” allows the direction of view to be acquired without deteriorating normal eye movements. This system is used in the USA in the Air Force, the Marines, in NASA and in commercial air traffic. It serves both training purposes, namely improving the ability of the observer to concentrate, as well as design purposes for determining better designs of cockpits, instrument panels and similar devices. Further areas of application are opened up in reviewing the effectiveness of advertising in television programs, in the registration of recognition possibilities in road traffic and in determining learning disabilities in children.
German Patent DE 195 41 301 provides a controlling means for acquiring what an observer has focused on and observed on a display means observed, whereby the means controlling generate a signal for controlling the display means such that the resolution of the display means in the observed area is higher than in the non-observed area of the display means.
In such devices for acquiring the viewing direction or what an observer has focused on, it is mainly the eyes of the person that are utilized, and the direction of view is acquired on the basis of the alignment of the pupil in the eye. The image signals of the eye registered by a camera are interpreted by an image computer and converted into control signals. However, since the recognition of the pupil from the image signals of a camera, is an extremely complicated procedure, a high calculating performance of the computer unit is required. Such computer units are expensive since they must work with large data sets generated from the image signals in an optimally short time. The required computing power is significantly greater than available in current PCs. The application of such a means is therefore limited to few areas of employment.
A device for detecting the pupil movement for controlling, in particular, a computer on the basis of a menu is previously known from Ebisawa, Y., “Unconstrained Pupil Detection Technique using Two Light Sources and the Image Difference Method”, Visualization and Intelligent Design in Engineering and Architecture II, Proceedings of 2nd International Conference on Visualization Tools for Intelligent Design in Engineering and Architecture, La Coruna, Spain, June 1995, ISBN 1-85312-319-5, 1995, Southhampton, UK, Comput. Mech. Publications, UK, pages 79-89, XP002052717. The apparatus in this referance uses two light sources that are implemented as infrared light sources and are arranged at an angle relative to one another, as well as a video camera in combination with a computer unit that subtracts the image signals of the light sources driven in alternation from one another in order to generate difference image signals. This apparatus differs from the subject matter of the present application in that the light sources according to the reference have the same light emission. The subject matter of the present application is therefore not known from the reference, nor is there an obvious teaching thereof.
Using only a single infrared light source for generating image signals for detecting eye movement is known from Ebisawa, Y. et al., “Non-invasive Eye-gaze Position Detecting Method Used on Man/Machine Interface for the Disabled”, Computer based Medical Systems, Proceedings of the Fourth Annual IEEE Symposium, Baltimore, Md. USA, May 12-14 1991, ISBN 0-8186-2164-8, 1991, Los Alamitos, Calif., USA, IEEE Comput. Soc. Press, USA, pages 374-380, XP000350289, Section “2.2.2 Camera Rotation system”.
U.S. Pat. No. 4,950,069 discloses a device for detecting the eye movement and for generating a control signal for a computer. In combination with only a single infrared light source, an infrared camera generates image signals that are processed in a computer for generating the control signals.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to specify a method and an apparatus of the species initially cited with which it is possible to manage with lower computing power and, thus, lower costs.
This object is inventively achieved by a method for operating a device for acquiring the location of a characteristic region of a person and generating a control signal for a device dependent on this location which comprises the steps of generating first and second image signals of a characteristic region with a camera, and two light sources (one with an emission different from the other), subtracting one image signal from the other, analyzing the difference signal thus produced, determining location coordinates of the characteristic region, and generating a signal dependent on these location coordinates.
This object is also inventively achieved by an apparatus for acquiring the location of a characteristic region of a person and for generating a control signal for a device dependent on this location having an image signal generator for generating first and second image signals of the characteristic region with a camera, two light sources with a second having a light emission different from the first, a subtractor which calculates a difference image signal from the two image signals, an analyzer and locator for determining the location coordinates of the characteristic region, and a location coordinate generator for generating a signal dependent on the location coordinates.
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An advantage of the method is that, in a first process, (method step (a)) the method steps generate first and second image signals of the characteristic area with a camera, whereby the first image signals are generated with a first light source and the second image signals are generated with the first and an additional, second light source having narrow-band light emission. The first and second image signals consequently differ from one another particularly due to the influence of the second light source in a method step (b). When the first and second image signals are subtracted for generating difference image signals, then the difference image signals contain only the information that are generated by the second light source. The influences of the first light source on the image signals as well as reflections from the environment of the person are thus eliminated to the farthest-reaching extent. When the difference signals are analyzed in view of the signals generated by the characteristic area and the location coordinates of the characteristic area are identified, then a control signal dependent on the location coordinates can be generated and a device can be operated or controlled. To be cited as a particular advantage of this method is that, in particula
Manuel George
Schiff & Hardin & Waite
Siemens Aktiengesellschaft
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