Abstract:
In order to minimize light diffraction along the direction of switching and more particularly light diffraction into the acceptance cone of the collection optics, in the present invention, micromirrors are provided which are not rectangular. Also, in order to minimize the cost of the illumination optics and the size of the display unit of the present invention, the light source is placed orthogonal to the rows (or columns) of the array, and/or the light source is placed orthogonal to a side of the frame defining the active area of the array. The incident light beam, though orthogonal to the sides of the active area, is not however, orthogonal to any substantial portion of sides of the individual micromirrors in the array. Orthogonal sides cause incident light to diffract along the direction of micromirror switching, and result in light ‘leakage’ into the ‘on’ state even if the micromirror is in the ‘off’ state. This light diffraction decreases the contrast ratio of the micromirror. The micromirrors of the present invention result in an improved contrast ratio, and the arrangement of the light source to micromirror array in the present invention results in a more compact system. Another feature of the invention is the ability of the micromirrors to pivot in opposite direction to on and off positions (the on position directing light to collection optics), where the movement to the on position is greater than movement to the off position. A further feature of the invention is a package for the micromirror array, the package having a window that is not parallel to the substrate upon which the micromirrors are formed. One example of the invention includes all the above features.
Abstract:
A spatial light modulator is disclosed, along with a method for making such a modulator that comprises an array of micromirror devices. The center-to-center distance and the gap between adjacent micromirror devices are determined corresponding to the light source being used so as to optimize optical efficiency and performance quality. The micromirror device comprises a hinge support formed on a substrate and a hinge that is held by the hinge support. A mirror plate is connected to the hinge via a contact, and the distance between the mirror plate and the hinge is determined according to desired maximum rotation angle of the mirror plate, the optimum gap and pitch between the adjacent micromirrors. In a method of fabricating such spatial light modulator, one sacrificial layer is deposited on a substrate followed by forming the mirror plates, and another sacrificial layer is deposited on the mirror plates followed by forming the hinge supports. The two sacrificial layers are removed via the small gap between adjacent mirror devices with spontaneous vapor phase chemical etchant. Also disclosed is a projection system that comprises such a spatial light modulator, as well as a light source, condensing optics, wherein light from the light source is focused onto the array of micromirrors, projection optics for projecting light selectively reflected from the array of micromirrors onto a target, and a controller for selectively actuating the micromirrors in the array.
Abstract:
A method and apparatus are disclosed for increasing contrast in micromirror-based image display devices. As a result the displayed image is a more faithful reproduction of the original and is more pleasing to human perception than is possible with a low contrast display. The method and apparatus comprise a micromirror design and a modulation scheme for driving micromirrors with a combination of analog and digital techniques to achieve partial and full micromirror deflection. The analog techniques permit the mirrors to be deflected to positions intermediate between the resting position and the position of maximum deflection. These intermediate deflections appear as intermediate light levels in an image. Compared to digital modulation, the analog techniques provide an increase in the number of light levels that can be displayed by a system that is limited by its incoming data rate and maximum micromirror speed.
Abstract:
A method for forming a MEMS device is disclosed, where a final release step is performed just prior to a wafer bonding step to protect the MEMS device from contamination, physical contact, or other deleterious external events. Without additional changes to the MEMS structure between release and wafer bonding and singulation, except for an optional stiction treatment, the MEMS device is best protected and overall process flow is improved. The method is applicable to the production of any MEMS device and is particularly beneficial in the making of fragile micromirrors.
Abstract:
An integrated driver for controlling operations of display systems having spatial light modulators that are operated in binary states is provided.
Abstract:
A spatial light modulator is disclosed, along with a method for making such a modulator that comprises an array of micromirror devices. The center-to-center distance and the gap between adjacent micromirror devices are determined corresponding to the light source being used so as to optimize optical efficiency and performance quality. The micromirror device comprises a hinge support formed on a substrate and a hinge that is held by the hinge support. A mirror plate is connected to the hinge via a contact, and the distance between the mirror plate and the hinge is determined according to desired maximum rotation angle of the mirror plate, the optimum gap and pitch between the adjacent micromirrors.In a method of fabricating such spatial light modulator, one sacrificial layer is deposited on a substrate followed by forming the mirror plates, and another sacrificial layer is deposited on the mirror plates followed by forming the hinge supports. The two sacrificial layers are removed via the small gap between adjacent mirror devices with spontaneous vapor phase chemical etchant. Also disclosed is a projection system that comprises such a spatial light modulator, as well as a light source, condensing optics, wherein light from the light source is focused onto the array of micromirrors, projection optics for projecting light selectively reflected from the array of micromirrors onto a target, and a controller for selectively actuating the micromirrors in the array.
Abstract:
A spatial light modulator having a photo-detector for use in digital display systems is provided. The spatial light modulator modulates a light beam having multiple light components of different frequencies so as to produce color images. The photo-detector detects a component of the light beam and generates a timing signal. The timing signal is then used to synchronize the operation of the spatial light modulator with the sequence of incident light color components.
Abstract:
Methods and apparatus for selectively updating memory cells of a memory cell array are provided. The memory cells of each row of the memory cell array are provided with a plurality of wordlines. Memory cells of the row are activated and updated by separated wordlines. In an application of display systems using memory cell arrays for controlling the pixels of the display system and pulse-width-modulation (PWM) technique for displaying grayscales, the pixels can be modulated by different PWM waveforms. The perceived dynamic-false-contouring artifacts are reduced thereby. In another application, the provision of multiple wordlines enables precise measurements of voltages maintained by memory cells of the memory cell array.
Abstract:
A method for making a MEMS device comprises forming a plurality of micromechanical elements on a first substrate; forming circuitry and electrodes on a second substrate, the first and second substrates extending in a plane in X and Y directions; aligning the first and second substrates in the X and Y directions and moving the substrates toward each other in a Z direction and bonding the first and second substrates with a gap therebetween in the Z direction to form an assembly; singulating the assembly into assembly portions; and altering the gap for each assembly portion. Another embodiment involves aligning the first and second substrates in the X and Y directions and moving the substrates toward each other in a Z direction and bonding the first and second substrates with a gap therebetween in the Z direction to form an assembly; actuating and testing the micromechanical elements of the assembly; and altering the gap for each assembly. A further embodiment involves aligning the first and second substrates in the X and Y directions and moving the substrates toward each other in a Z direction and bonding the first and second substrates with a gap therebetween in the Z direction to form an assembly; wherein the micromechanical elements are actuated while bonding of the substrates.
Abstract:
A MEMS device is disclosed comprising: a substrate; a movable micromechanical element movable relative to the substrate; a connector and a hinge for allowing movement of the micromechanical element, wherein the connector is made of a material different than the hinge. In another embodiment of the invention, the connector has a conductivity greater than the hinge. In a further embodiment of the invention, the hinge provides at least 90% of the restoring force to the MEMS device, and the connector provides 10% or less of the restoring force. In a further embodiment of the invention, the connector and the hinge have different spring constants. In a still further embodiment of the invention, the connector experiences a lower strain at maximum deflection of the micromechanical element than the hinge.