Active tuning of a torsional resonant structure

#The present invention relates to scanned light devices and, more particularly, to scanned light beam displays and imaging devices for viewing or collecting images.

#A variety of techniques are available for providing visual displays of graphical or video images to a user. In many applications cathode ray tube type displays (CRTs), such as televisions and computer monitors produce images for viewing. Such devices suffer from several limitations. For example, CRTs are bulky and consume substantial amounts of power, making them undesirable for portable or head-mounted applications.

#Matrix addressable displays, such as liquid crystal displays and field emission displays, may be less bulky and consume less power. However, typical matrix addressable displays utilize screens that are several inches across. Such screens have limited use in head mounted applications or in applications where the display is intended to occupy only a small portion of a user's field of view. Such displays have been reduced in size, at the cost of increasingly difficult processing and limited resolution or brightness. Also, improving resolution of such displays typically requires a significant increase in complexity.

#FIG. 1 is a diagrammatic representation of a display aligned to a viewer's eye.

#FIG. 2A is a combined image perceived by a user resulting from the combination of light from an image source and light from a background.

#FIG. 2B is an image perceived by a user from the display of FIG. 1 where the background light is occluded.

#As shown in FIG. 6, a scanned beam display 70 according to one embodiment of the invention is positioned for viewing by a viewer's eye 72. While the display 70 is presented herein is scanning light into the eye 72, the structures and concepts described herein can also be applied to other types of displays, such as projection displays that include viewing screens.

#The display 70 includes four principal portions, each of which will be described in greater detail below. First, control electronics 74 provide electrical signals that control operation of the display 70 in response to an image signal VIM from an image source 76, such as a computer, television receiver, videocassette player, DVD player, remote sensor, or similar device.

#The second portion of the display 70 is a light source 78 that outputs modulated light beams 80, each having a modulation corresponding to information in the image signal VIM. The light source 78 may utilize coherent light emitters, such as laser diodes or microlasers, or may use non-coherent sources such as light emitting diodes. Also, the light source 78 may include directly modulated light emitters such as the light emitting diodes (LEDs) or may include continuous light emitters indirectly modulated by external modulators, such as acousto-optic modulators.