Patent ID: 7177083
Filing Date: 2007-02-13
Classification: G02B,H04N

Abstract:
1. A display device for generating an image perceivable by a viewer as being superimposed on an object located in an object plane, said device comprising: an image generating device for generating the image projected to an image plane and a superimposing unit, the image generating device and the superimposing unit being mounted on a head wearable support device, and the image generating device comprising a variable focusing unit by which the distance from the image plane to the support device is adjustable, the variable focusing unit comprising a lens having a variable refractive index located in an optical path between the image generating device and the viewer and a control unit for adjusting the refractive index of the lens, the control unit applying a variable electrical signal to the variable refractive lens to alter the refractive index of the lens and to consequently vary the focusing power of the lens; the superimposing unit comprising a first beam splitter and a second beam splitter wherein, said first beam splitter deflects light coming from the image generating device to said second beam splitter which in turn deflects the light to the viewer, and wherein the light coming from the object is transmitted through said second beam splitter to the viewer, a measurement module that receives light coming from the object that passes through the first beam splitter and senses the object located in the object plane from the received light; wherein, when the support device is worn on the head of the viewer, the superimposing unit superimposes the generated image in a field of view including the object as seen by the viewer and the control unit adjusts the electrical signal applied to the variable refractive index lens to alter the refractive index of the lens to focus the image based on a signal from the measurement module, such that the image plane substantially coincides with the object plane and the object and the image are seen as simultaneously substantially equally focused by the user when the user accommodates to focus the object.