US20090009860A1

US20090009860A1 - Flexible members for moving screens in display systems

Info

Publication number: US20090009860A1
Application number: US11/956,684
Authority: US
Inventors: Stephen Wesley Marshall
Original assignee: Texas Instruments Inc
Current assignee: Texas Instruments Inc
Priority date: 2007-07-02
Filing date: 2007-12-14
Publication date: 2009-01-08
Also published as: US8444271B2; US8031403B2; US20120019918A1; US20090009871A1

Abstract

For reducing artificial effects, especially the speckle effects, in display systems employing light valves, a movable screen is provided in the display system. The screen motion is enabled by attaching the screen to flexible elements that are connected to non-movable member of the display system.

Description

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This US patent application claims priority from co-pending U.S. provisional patent application Ser. No. 60/947,640 to Marshall et al. filed Jul. 2, 2007, the subject matter of which is incorporated herein by reference in its entirety.

TECHNICAL FIELD OF THE DISCLOSURE

The technical field of this disclosure relates to the art of screens for use in display systems, and more particularly, to the art of flexible members for moving screens of display systems.

BACKGROUND OF THE DISCLOSURE

In recent years, solid-state light illuminators, such as LASERs and light-emitting-diodes (LEDs), and other narrow-banded illuminators capable of producing phase-coherent light (e.g. wavelength specific plasma lamps) have drawn significant attention as alternative light sources to traditional light sources (e.g. arc lamps) for use in display systems, especially display systems employing light valves, due to many advantages, such as compact size, greater durability, longer operating life, and lower power consumption.
However, most of the current solid-state illuminators and narrow-banded illuminators cause artificial effects, such as speckle effects, during display applications. These artificial effects can be perceived by viewers; and thus, degrading the viewing experience.
Therefore, what is desired is a method for eliminating the artificial effects, especially the speckle effect, in display applications using display systems with light valves.

SUMMARY OF THE DISCLOSURE

In one example, a screen for use in a display system is disclosed. The screen is attached to a flexible element that holds the screen and a moving mechanism that moves the screen.
In another example, a method of displaying an image is disclosed. The method comprises: producing an image on a screen; and moving the screen relative to a view of the image using a flexible element and a screen driver, further comprising: holding the screen by the flexible element; and moving the screen relative to the viewer by the screen driver.
In yet another example, a display system is disclosed. The system comprises: a light valve comprising an array of individually addressable pixels; a screen attached to and held by a flexible element; a moving mechanism attached to the screen for moving the screen; and a set of optical elements for directing light from the light valve onto the screen.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 schematically illustrates a side view of a structure wherein a screen is movably held by a fixed member of a display system;

FIG. 2 schematically illustrates a front view of the screen portion in FIG. 1;

FIG. 3 schematically illustrates an exploded view of an exemplary flexible element that is attached to the a fixed frame and the screen for holding the screen while enabling the screen to move;

FIG. 4 schematically illustrates an exploded view of another exemplary flexible element that is attached to the a fixed frame and the screen for holding the screen while enabling the screen to move;

FIG. 5 diagrammatically illustrates an exemplary driving mechanism provided in the movable screen in FIG. 1;

FIG. 6 diagrammatically illustrates an exploded view of the driving mechanism in FIG. 5;

FIG. 7 schematically illustrates another exemplary movable screen;

FIG. 8 schematically illustrates yet another exemplary movable screen;

FIG. 9 diagrammatically illustrates a method for moving the screen in FIG. 8;

FIG. 10 schematically illustrates an exemplary movement of the screen;

FIG. 11 a schematically illustrates another exemplary movement of the screen;

FIG. 11 b schematically illustrates another exemplary movement of the screen;

FIG. 12 schematically illustrates an exemplary screen having a lenticular array and a Fresnel lens, one of which can be moved;

FIG. 13 schematically illustrates yet another exemplary screen having a lenticular array, a Fresnel lens, and an optical diffuser, one of which can be moved;

FIG. 14 schematically illustrates yet another exemplary screen having a lenticular array, a Fresnel lens, and an optical diffuser, one of which can be moved;

FIG. 15 illustrates an exemplary display system with a movable screen; and

FIG. 16 schematically illustrates an exemplary illumination system of the display system in FIG. 15.

DETAILED DESCRIPTION OF SELECTED EXAMPLES

Disclosed herein is a mechanism for holding and moving screens of display systems so as to eliminate artificial effects, especially speckle effects. The mechanism comprises one or more flexible members. Each flexible member is substantially rigid along its length; while flexible in directions perpendicular to the length. By attaching each flexible member to a fixed member of the display system and the screen to be moved, the screen is movable along directions perpendicular to the length of the flexible member. However, screen motion along the length of the flexible member is substantially prevented.
The screen motion is capable of reducing artificial effects (e.g. speckle effects) by showing each artificial effect in multiple different locations within the integration time of the viewers' eyes. Viewers' eyes collect the artificial effects from different locations and average the perceived artificial effects. As a consequence, viewers perceive the artificial effect as a background; thus making the image appear substantially free of the artificial effect.
The movable screen will be discussed in the following with reference to selected examples. However, it will be appreciated by those skilled in the art that the following discussion is for demonstration purpose, and should not be interpreted as a limitation. Other variations within the scope of the disclosure are also applicable.
Referring to the drawings, FIG. 1 schematically illustrates a screen that is held by a fixed member of a display system and a set of flexible elements. In this example, screen 102 is held by screen frame 106. The screen frame (106) is connected to fixed (non-moving) member 100 of the display system through multiple flexible elements, such as element 104. The fixed member (100) can be a fixed member inside the body of the display system, such as the fixed chassis member, or alternatively, the cabinet of the display system, or other members that are not movable in the display system during image displaying.
With the flexible elements, the fixed member, and the screen frame, the screen (102) is held at the desired static position when screen motion is not desired; and is capable of moving relative to the fixed member (100) in displaying images when screen motion is desired.
For better illustrating movements of the screen relative to the fixed member, a static Cartesian coordinate O_cX_cY_cis established on the screen (102) with the origin O_caligned to the geometric center of the screen when the screen is not moved (e.g. at the desired static position). The Z_cdirection is along the normal direction of the screen; and the X_cand Y_cdirections are in the plane of the screen (102). It is noted that the O_cX_cY_ccoordinate is static; and does not move with the screen when the screen is moved during image displaying applications. The geometric center of the screen is aligned to the coordinate origin O_cwhen the screen is not moving; and is away from the coordinate origin when the screen is moving, as will be illustrated in FIG. 10 and FIG. 11 a afterwards.
With reference to the Cartesian coordinate O_cX_cY_c, the screen (102) is capable of moving in the X_cY_cplane. The movement can be in any desired pattern, such as a circular pattern, a spiral pattern, any combinations thereof, or many other forms, as will be detailed afterwards with reference to FIG. 10 and FIG. 11 a. Regardless of different moving patterns, the screen is preferably (though not required) moved at or in the vicinity of the resonant frequency of the system that comprises the flexible elements and their connections to the screen (the screen frame) and the fixed member of the display system.
In a display application that generates an artificial effect (e.g. speckle effect) on the screen, the artificial effect can be imaged at multiple different locations of each retina of the viewer's eyes. The number of such images, as well as the duration of each image depends upon the frequency of the screen motion (e.g. the motion in the X_cY_cplane). Within the integration time of the viewers' eyes, viewers' eyes integrate the images of the artificial effect at different locations; and average the perceived artificial effects. As a consequence, viewers perceive the artificial effect as a background; while the image appears substantially free of the artificial effect. In one example wherein screen comprises an optical diffuser with a full-width-half-maximum (FWHM) diffusion angle of 5° or less, such as 3° degrees or less, or 2° degrees or less, the speckle effect can be reduced by 10 db or higher, such as 15 db or higher, 20 db or higher, or 25 db or higher.
In order to not introduce additional artificial effects due to the screen motion, it is preferred that 1) the screen substantially does not rotate relative to its geometric center during screen motion; 2) the screen substantially does not tilt relative to the fixed member during screen motion; and/or 3) the screen substantially does not move along the normal direction (e.g. along the Z_cdirection) of the screen.
The front view of the attachment of the screen to the fixed member is schematically illustrated in FIG. 2. Referring to FIG. 2, screen 102 is held by screen frame 106. The screen frame (106) is attached to the fixed member (100) using flexible elements, such as elements 104. The flexible elements in this example are deployed around the parameter of the screen frame. It is noted that FIG. 2 is for demonstration purpose, and illustrates only one of many possible examples. The flexible elements can be deployed in any desired ways. For example, the flexible elements can be uniformly distributed on the sides of the screen frame. In another example, the flexible elements can be non-uniformly distributed in a side of the screen frame, in which instance, the flexible elements can be distributed according to the distribution of the tension or torque exerted to the screen frame when the screen is moving with a desired moving pattern. It is preferred that the deployment of the flexible elements ensures that 1) the screen is capable of moving in a plane parallel to the screen (e.g. the X_cY_cplane); 2) the screen is substantially prevented from moving along the normal direction (e.g. along the Z_cdirection) of the screen; 3) the screen substantially does not rotate relative to its geometric center during moving; and/or 4) the screen substantially does not tilt relative to the fixed member.
The flexible elements can be any suitable elements, and preferably those flexible elements that have resonant frequencies; and are strong enough such that the screen frame (as well as the screen and other attached elements) can be held at the desired static position by a limited number (e.g. equal to or less than 500) of such flexible elements. In order to avoid the screen moving along the normal direction of the screen (the Z_cdirection), it is preferred that the flexible elements are substantially rigid in at least one direction (e.g. along the length of the flexible element); and such direction is aligned to the normal direction of the screen. The flexible element can have one or more deformable directions, such as directions perpendicular to the normal direction of the screen, so as to allow the screen motion in the plane of the screen.
Even though not required, the flexible elements used in connecting the screen to the fixed member are preferably identical to avoid possible screen tilt (displacement along the Z_cdirection) or rotate (the motion around the geometric center of the screen) of the screen during moving. When different types of flexible elements or the same type of flexible elements but with different mechanical properties are employed, different flexible elements can be utilized as combined flexible elements (e.g. flexible element pairs and flexible element triplets) such that the flexible element combinations exhibit substantially the same mechanical property. Each flexible combination can then be used in place of each single flexible element as illustrated in FIG. 1. By way of example, two different groups of flexible elements can be used. The flexible elements in the same group have substantially the same mechanical properties; and the flexible elements in different groups have different mechanical properties. Each flexible element in one group can be combined with a flexible element in the other group so as to form a flexible element pair; and the flexible element pairs exhibit substantially the same mechanical property. Of course, more different groups of different flexible elements can be provided and combined as desired.
As is known by those skilled in the art that human eyes are sensitive to movements at frequencies in the range from 7 Hz to 30 Hz. Low contrast defects or smudges on the screen that are not objectionable when the screen is static, become noticeable when the screen is in motion; and particularly when the motion is in the 7 Hz to 30 Hz range. In order to avoid introducing perceivable artificial effects due to the screen motion, the screen preferably moves at a frequency compatible with the motion sensitivity of human eyes, such as lower than 7 Hz or higher than 30 Hz. For example, the screen can be moved at a frequency of 7 Hz or lower, such as 5 Hz or lower, or 3 Hz or lower, but preferably higher than 0.1 Hz. Alternatively, the screen can be moved can be at a frequency substantially equal to or higher than 30 Hz, such as 32 Hz or higher or 35 Hz or higher, but preferably lower than 300 Hz. Accordingly, the flexible elements selected and arranged for holding the screen frame (and the screen) each can have an intrinsic spring rate such that the effective resonant frequency of the flexible elements with the specific screen frame arrangement is approximately equal to the desired motion frequency of the screen. As an example, each flexible element may have a resonant frequency of 7 Hz or lower or 30 Hz or higher.
Still, in order to avoid introducing perceivable artificial effects or causing the screen motion to be perceived by the viewer, the maximum displacement of the screen is preferably, though not required, equal to or less than 2000 image pixels or less, 1000 image pixels or less, 500 image pixels or less, 100 image pixels or less, 50 image pixels or less, and more preferably 12 image pixels or less. In one example, the maximum displacement of the moving screen can be 10 mm or less, 5 mm or less, 3 mm or less, 1 mm or less, 500 microns or less, 200 microns or less, or even 120 microns or less. Accordingly, for a specific screen design with given weight and other mechanical properties, the flexible elements selected for holding the screen preferably each have the maximum displacement at the resonant frequency corresponding to the allowed maximum displacement of the moving screen.
A group of candidates of flexible elements is springs—with intrinsic spring rates compatible with the desired resonant frequency of the screen system, such as cantilever spring rods, extension springs, compression springs, torsion springs, double torsion springs, and magazine springs. Other flexible elements, such as flat strip forms, wire forms, straightened wire and pins, and rings and retainers, are also applicable, though less preferred.
In examples of springs, the opposite ends along the length of each spring are securely connected to the screen frame and the fixed member of the display system so as to hold the screen in front of the fixed member. For demonstration purposes, FIG. 3 schematically illustrates an exemplary scheme that uses music wire springs for holding the screen frame (and screen).
Referring to FIG. 3, music wire spring 104 in this example is an elongated spring rod. The spring rod is substantially non-extendable (rigid) along the length of the spring rod, but is subject to deforming along the width and/or the height direction. The length of the spring rod is aligned to the normal direction of the screen (e.g. the Z_cdirection in the Cartesian coordinate). One end of the spring rod (104) is securely anchored at the fixed member (100) such that the anchored end does not move; while the other end of the spring rod is connected to the screen frame 106. The spring rod (104) in this attachment configuration behaves as a cantilever spring rod—one end (attached to the fixed member) of the spring rod is fixed; while the other end (attached to the screen frame) is subject to moving in the X_cY_cplane.
For simplicity and demonstration purposes, FIG. 3 illustrates only one spring rod (104) and the attachment of the spring rod to the screen frame (106) and the fixed member (100). The screen of a display system can be held by many such spring rods, as schematically illustrated in FIG. 1. For example, ten spring rods can be employed with four spring rods at each top and bottom sides of the screen frame, and one at each side of the screen frame. These springs rods can be selected as the same spring rod (104) as discussed above with reference to FIG. 3, and can be attached to the screen frame and the fixed member in the same way. Alternatively, spring rods with different mechanical properties can be deployed along the parameter of the screen frame and used for connecting the screen frame to the fixed member. In one example, a group of spring rods with substantially the same mechanical property can be deployed on the top and/or the bottom side of the screen frame for connecting the top side of the screen frame to the fixed member. Another group of spring rods with the substantially the same mechanical property, but are different from the spring rods in the first group, can be deployed on the vertical sides of the screen frame for connecting the vertical sides of the screen frame to the fixed member.
Other than attaching the spring rod to the screen frame and the fixed member as illustrated in FIG. 3, a spring rod can be attached as a co-axial spring rod, as schematically illustrated in FIG. 4.
Referring to FIG. 4, spring rod 104 is disposed inside tubing 108. The tubing (108) is disposed behind the screen frame (106) and the fixed member (100). The opening of the tubing is aligned to the position wherein a flexible element is to be used for connecting the screen frame to the fixed member. The end of spring rod 104 inside tubing 108 is securely anchored to the tubing such that the end of the spring rod is substantially non-movable relative to the tubing or non-movable to the fixed member (100). The spring rod (104) passes through the body of fixed member 100; and is attached to the screen frame (106) at the other end as illustrated in FIG. 4. Though not required, the flexible element (104) is connected to and thus held by fixed member 100. The other end of the spring rod, which is attached to the screen frame, however, is subject to moving so as to allow for the desired screen motion.
The flexible elements and their attachments enable the screen motion; while the motion is driven by a screen driver. Moving the screen with a screen driver can be implemented in many ways as will be discussed in the following. Regardless of different screen drivers and different deployments, it is preferred that the screen does not rotate around its geometric center, tilt (having a screen portion moving along the normal direction of the screen), or move along the normal direction of the screen. It is preferred that the screen as a rigid body moves substantially in the X_cY_cplane; while the trajectory of any points on the screen can be in any moving patterns, which will be discussed below. The screen driver can be in any suitable form, such as actuators and step-motors. As an example illustrated in FIG. 5, a screen driver, which is implemented as two voice coils, is provided for moving the screen.
Referring to FIG. 5, voice coils 112 and 116 are provided for causing the screen to move in a desired pattern. Specifically, each voice coil is attached to a frame nose, such as frame noses 110 and 114 that are fixed to the screen frame. An exemplary voice coil is schematically illustrated in FIG. 6.
Referring to FIG. 6, voice coil 112 comprises coil base 124, coil 125, magnets 126, 130, and 128, and moving stage 132. The coil base (124) can be Bezel or any of a number of other suitable materials. The coil base (124) in this example is attached to a static element of the display system, such as a portion of fixed member 100 that is illustrated in FIG. 1, or can be any suitable elements that do not move in the display system. The coil (125) is disposed with one end being anchored to the static coil base (124); and the other end being free (or alternatively being anchored). Magnets 126, 130, and 128 are disposed such that the at least one of the magnets is movable so as to cause moving stage 132 to move. In this example, all magnets 126, 130, and 128 are attached to moving stage 132; and are movable so as to drive the moving stage (132) to move. The moving stage (132) is attached to the frame nose, such as frame nose 110, for moving the screen frame by applying a force to the frame nose.
When an alternate electrical current (AC current) is introduced to the coil (through ends of the coil, which are not shown), the magnets moves under the current-induced force. The magnets drive the moving stage (132) to move; and the moving stage drives the frame nose to move by applying a force to the frame nose along the desired direction as illustrated in FIG. 5. The direction of the applied force can be controlled through the alignment of the moving stage (132) to the frame nose, specially, through the angle between the moving stage (132) and the edge of the frame nose in contact to the moving stage.
Referring again to FIG. 5, the moving stage of voice coil 112 applies force F₁to frame nose 110 along direction 118 that passes through the mass center (or the geometric center) O_sof the screen (or the combination of the screen and the screen frame). Force F₁causes the screen frame to move along direction 118. Along direction 120 that is perpendicular to direction 118 and passes through center O_s, the moving stage of voice coil 116, which is substantially the same as voice coil 112, applies force F₂to frame nose 114 so as to move the screen frame along direction 120.
Forces F₂and F₁have substantially the same amplitude. Because directions 118 and 120 both pass through center O_sof the screen, neither force causes the rotation of the screen. Because forces F₁and F₂are substantially in the plane (e.g. the plane of the screen), either one or both of the applied forces F₁and F₂do not cause tilt of the screen. Under the driving forces F₁and F₂, the screen frame (as well as the enclosed screen) is capable of moving relative to the fixed member (100 in FIG. 1); while the movement is substantially in the plane of the screen (e.g. the X_cY_cplane).
Another exemplary arrangement of the screen driver is schematically illustrated in FIG. 7. Referring to FIG. 7, voice coils 112 and 114, each of which can be voice coil 112 discussed above with reference to FIG. 6, are symmetrically arranged on the major sides (e.g. the left and bottom sides) of the screen frame. Voice coil 112 applies force F₁along the horizontal direction that passes through center O_s; and voice coil 114 applies force F₂along the vertical direction passing through center O_s. Forces F₁and F₂may or may not have the same amplitude. However, because the orthogonal forces F₁and F₂both are applied along directions passing through the mass center of the screen frame, the screen is not caused to rotate by the applied forces F₁and F₂. Because the two forces are applied along directions substantially in the same plane (e.g. the plane of the screen), the two forces do not cause tilt of the screen.
Another exemplary arrangement of the screen driver is schematically illustrated in FIG. 8. Referring to FIG. 8, screen 102 is held by screen frame 106. Spring rods 134, 136, 138, 140, 142, 144, 146, and 148 connect the screen frame (106) to fixed member 100 of the display system. In this example, the spring rods each can be the spring rod (104) as discussed above with reference to FIG. 3 and FIG. 4; and each spring can be connected to the screen frame and the fixed member in the same way as discussed above with reference to FIG. 3 or FIG. 4, except that the screen frame and the spring rods, in this example, are substantially in the same plane, such as the plane of the screen.
For moving the screen frame so as to move the screen held by the screen frame, voice coils 112 and 114 are attached to the screen frame (106) in the same way as discussed above with reference to FIG. 7. As an alternative feature, motion detectors 150 and 152 can be attached to the screen frame so as to dynamically detect the moving pattern, such as the position and speed (linear or angular), of the screen frame (or the screen).
As discussed above, the voice coils move the screen frame by the moving stages of the voice coils. The movements of the moving stages are caused by the AC currents in the coils of the voice coils. In other words, by controlling the AC currents in the coils, the moving stages can be moved in desired patterns. As an example, FIG. 9 diagrammatically illustrates a control unit for driving the voice coils illustrated in FIG. 8.
Referring to FIG. 9, the driving unit comprises invert amplifier 154, X-axis VC driver 156, Y-axis VC driver 162, X-position sensor 164, and Y-position sensor 164. The X-axis VC driver (156) and Y-axis VC driver 162 generate driving signals for the coils of the voice coils so as to cause oscillations of the coils. The frequency of the oscillation is substantially equal to or in the vicinity of the resonant frequency of spring mass system (comprising the spring rods and their specific attachments to the screen frame and the screen). The driving unit can be used for driving the screen to move in a desired pattern, such as a circular moving pattern as schematically illustrated in FIG. 10.
Referring to FIG. 10, the screen (and the screen frame) is represented by a point mass at the mass center of the screen frame because the screen frame and the screen are substantially rigid bodies. At the time when the screen frame is not moving, the mass center is at the origin O_cof the Cartesian coordinate O_cX_cY_c, as illustrated in FIG. 1. For better describing the motion of the screen frame, a moving Cartesian coordinate O_sX_sY_sis established, wherein the O_sX_sY_scoordinate is aligned to the static O_cX_cY_ccoordinate when the screen frame is not moving.
The screen can perform a circular motion, for example, around the origin O_c(the mass center of the screen frame at the natural resting state) of the static coordinate O_cX_cY_c. The trajectory of the mass center of the screen frame forms a circle, as illustrated by the dashed line in FIG. 10, with the origin of the circle at O_c. During the circular motion, it is preferred that the axes (X_s, Y_s, and Z_s) of the moving coordinate O_sX_sY_sdo not change their directions; and the origin O_sof the O_sX_sY_scoordinate circularly moves around origin O_c. The frequency of the circular motion is preferably compatible with the motion sensitivity of human eyes. The radius of the circle, which is the maximum displacement of the moving screen during moving, can be 10 mm or less, 5 mm or less, 3 mm or less, 1 mm or less, 500 microns or less, 200 microns or less, or even 120 microns or less.
The above circular motion can be accomplished by generating driving forces F₁and F₂(as illustrated in FIG. 5 through FIG. 8) with a 90° degrees phase difference, and the waveforms of the driving signals can be quadrature or sinusoidal waveforms.
From the origin O_cto the maximum displacement M, the screen can move along any desired trajectories. For example, the screen can be moved from the origin O_cto the maximum displacement M along a straight line connecting the origin O_cand M. Alternatively, the screen can be moved from the origin O_cto the maximum displacement M along a spiral curve as schematically illustrated in FIG. 11 a.
Referring to FIG. 11 a, the screen frame and the enclosed screen are represented by a point mass at the mass center of the screen frame and screen combination. When the screen is not moving, the moving coordinate O_sX_sY_sis aligned to the static coordinate O_cX_cY_c. Driven by the frame driver (e.g. the voice coils), the screen (e.g. the mass center O_s) moves from the origin O_cto the maximum displacement O_cM along a spiral trajectory as illustrated by the dashed curve. When the screen is at the maximum displacement, the screen moves along a circle as discussed above with reference to FIG. 10.
In yet another example as schematically illustrated in FIG. 11 b, the screen can move from its original O_cto the maximum displacement O_xM along the dashed spiral curve; and returns to the origin O_cfrom the maximum displacement along another spiral trajectory as illustrated by the solid-curve. The frequency of the spiral motion can be defined as 2×π/T, wherein T is the time of the screen moving from the origin O_cto the maximum displacement O_cM and back to the origin O_c. The frequency of such spiral motion is preferably compatible with the motion sensitivity of the human eye. The maximum displacement (the amplitude of vector O_cM) of the moving screen can be 10 mm or less, 5 mm or less, 3 mm or less, 1 mm or less, 500 microns or less, 200 microns or less, or even 120 microns or less.
The spiral trajectories as discussed above with reference to FIG. 11 a and FIG. 11 b can take any suitable spiral forms, such as Archimedean spirals, logarithmic spirals, Fermat's spirals, hyperbolic spirals, Cornu spirals, lituus spirals, Fibonacci spirals, golden spirals, and other two-dimensional spiral forms.
The moving screen, which is held by the screen frame, of a display system can be screens with any desired configurations. For example, the screen may comprise multiple optical elements, such as a lenticular array, an optical diffuser, a Fresnel lens, or other desired optical components.
In one example, a screen (166) may comprise lenticular array 170 and Fresnel lens 168 as schematically illustrated in FIG. 12. The Fresnel lens can be replaced by or in combination with other desired optical elements. For reducing the artificial effects in images displayed on the screen (166), the screen (166) can be moved relative to the fixed member or the viewer. Alternatively, one of the lenticular array 170 and Fresnel lens 168 can be moved relative to the other. For example, the lenticular array (or the Fresnel lens) can be moved relative to the Fresnel lens (or the lenticular array). The movement can be accomplished in the same way as moving the screen frame by attaching the desired components(s) to the screen frame.
In another example, a screen (172) may comprise an optical diffuser (174), lenticular array 170, and Fresnel lens 168 with the optical diffuser being disposed between the lenticular array and the Fresnel lens, as schematically illustrated in FIG. 13. The optical diffuser preferably has a full-width-half-maximum (FWHM) diffusion angle of 5° or less, such as 3° degrees or less, or 2° degrees or less.
For reducing the artificial effects in images displayed on the screen (172), the screen (172) can be moved relative to the fixed member or the viewer. Alternatively, one or two of the components of lenticular array 170, Fresnel lens 168, and optical diffuser 174 can be moved relative to the other two or one components. For example, the optical diffuser can be moved relative to the lenticular array and the Fresnel lens. In another example, the optical diffuser and the Fresnel lens can be moved together relative to the lenticular array. The movement can be accomplished in the same way as moving the screen frame by attaching the desired components(s) to the screen frame.
In yet another example, the optical diffuser (174) and the Fresnel lens (168) can be bonded together to form an assembly as schematically illustrated in FIG. 14. The assembly can then be moved relative to the lenticular array of screen 176 in the same way as moving the screen frame by attaching the desired components(s) to the screen frame.
In addition to the holding and driving mechanisms, the movable screen may comprise other features. For example, a moving stopper can be provided for preventing the screen from moving when the screen motion is not desired. This feature can be useful for protecting the screen, especially during installation and transportation.
The screen as discussed above can be implemented in a wide range of display systems, one of which is schematically illustrated in FIG. 15. Referring to FIG. 15, display system 206 comprises illumination system 182, optical element 184, light valve 192, optical element 194, a screen unit that comprises screen 102, screen frame 106, flexible elements (e.g. flexible element 104), and fixed member 100), and screen controller 204.
Illumination system 182 provides illumination light for the display system. The illumination system may comprise a wide range of light emitting devices, such as lasers, light-emitting-diodes, arc lamps, devices employing free space or waveguide-confined nonlinear optical conversion and many other light emitting devices. In particular, the illumination system may comprise illuminators with low etendue, such as solid state light emitting devices (e.g. lasers and light-emitting-diodes (LEDs)).
When solid-state light emitting devices are used, the illumination system may comprise an array of solid-state light emitting devices capable of emitting different colors, such as colors selected from red, green, blue, and white. Because a single solid-state light emitting device generally has a narrow characteristic bandwidth that may not be optimal for use in display systems employing spatial light modulators, multiple solid-state light emitting devices can be used for providing light of each color so as to achieve optimal bandwidth for specific display systems. For example, multiple lasers or LEDs with slightly different characteristic spectra, such as 20 nm or less characteristic wavelength separation, can be used to produce a color light such that the characteristic spectra of the multiple lasers or LEDs together form an optimal spectrum profile of the display system. Exemplary laser sources are vertical cavity surface emitting lasers (VCSEL) and Novalux™ extended cavity surface emitting lasers (NECSEL), or any other suitable laser emitting devices. By way of example, FIG. 16 schematically illustrates an exemplary illumination system comprising laser emitting devices.
Referring to FIG. 16, illumination system 182 comprises laser R 206, laser G 208, and laser B 210 for emitting light of different colors, such as red, green, and blue colors. The laser light beams from laser emitting devices 206, 208, and 210 are combined and directed to the spatial light modulator through reflective mirror 211, optical filter 212 that passes the red light and reflects other color spectrums, and optical filter 214 that passes the red and green light components and reflects the blue light spectrum.
In other examples, the illumination system (182) may have any number of laser emitting devices capable of providing any suitable colors, preferably those colors selected from red, green, blue, yellow, magenta, cyan, white, or any combinations thereof.
Referring again to FIG. 15, the illumination light from the illumination system is directed to light valve 192 through optical element 184. Optical element 184 may comprise a group of optics, such as diffusers, condensing lens, and optical integrator. The light valve (192) comprises an array of individually addressable pixels, such as micromirrors, liquid-crystal-on-silicon cells, and other suitable devices. The light valve modules the incident light based on the image data (e.g. bitplanes) of the desired image; and the modulated light is directed to screen 102 through projection optical element 194.
The screen (102) is held by screen frame 106 that is attached to fixed member 100 (e.g. the cabinet of the display system) through flexible elements (e.g. element 104) as discussed above with reference to FIG. 1 through FIG. 14. A screen driver (not shown for simplicity) is attached to the screen for moving the screen with a desired pattern. The screen driver is connected to and thus controlled by controller 204, such as the controller discussed above with reference to FIG. 9.
It will be appreciated by those of skill in the art that a new and useful mechanism for moving a screen of a display system using flexible elements has been described herein. In view of the many possible embodiments, however, it should be recognized that the embodiments described herein with respect to the drawing figures are meant to be illustrative only and should not be taken as limiting the scope of what is claimed. Those of skill in the art will recognize that the illustrated embodiments can be modified in arrangement and detail. Therefore, the devices and methods as described herein contemplate all such embodiments as may come within the scope of the following claims and equivalents thereof.

Claims

1. A screen for use in a display system, wherein the screen is attached to a flexible element that holds the screen and a screen driver that moves the screen.

2. The screen of claim 1, wherein the flexible element is connected to the screen and a fixed member of the display system.

3. The screen of claim 2, wherein the fixed member is a cabinet of the display system.

4. The screen of claim 1, wherein the flexible element comprises at least one spring rod.

5. The screen of claim 4, wherein the screen driver is capable of moving the screen at a frequency determined based upon a resonant frequency of the spring rod and screen.

6. The screen of claim 4, wherein the screen driver is capable of moving the screen at a frequency lower than 7 Hz or higher than 30 Hz.

7. The screen of claim 1, further comprising an actuator attached to the screen for moving the screen.

8. The screen of claim 1, further comprising first and second actuators; wherein the first and second actuators are disposed such that first and second forces generated by the first and second actuators are applied to the screen along first and second directions that are perpendicular and pass through a mass center of the screen.

9. The screen of claim 4, wherein the screen is held by a screen frame that is connected to one end of the spring rod; and wherein the other end of the spring rod is securely anchored at a fixed member of the display system.

10. The screen of claim 1, wherein the flexible element is a co-axial spring rod.

11. The screen of claim 1, wherein the screen is held by a set spring rods that are deployed around the parameter of a screen frame that holds the screen.

12. The screen of claim 1, wherein the flexible elements are connected to the screen such that a motion of the screen along the normal direction of the screen is absent.

13. The screen of claim 4, wherein the spring rod is substantially rigid along the length of the spring rod.

14. A method of displaying an image, comprising:

producing an image on a screen; and

moving the screen relative to a viewer of the image using a flexible element and a screen driver, further comprising:

holding the screen by the flexible element; and

moving the screen relative to the viewer by the screen driver.

15. The method of claim 14, wherein the step of moving the screen further comprises:

moving the screen such that a mass center of the screen moved relative to the viewer; while the screen substantially does not tilt or rotate around the mass center.

16. The method of claim 14, wherein the screen is substantially not moved along a normal direction of the screen.

17. The method of claim 14, wherein the screen moves circularly at a frequency lower than 7 Hz or higher than 30 Hz.

18. The method of claim 14, wherein the maximum displacement of the screen during moving is equal to or less than 5 mm.

19. The method of claim 15, further comprising:

applying first and second forces to the screen, wherein the first and second forces are applied along first and second directions that are perpendicular and pass through a mass center of the screen.

20. The method of claim 19, wherein the first and second forces are substantially in a plane of the screen.

21. The method of claim 20, wherein the first and second forces are applied by first and second actuators; and wherein the screen is held by a plurality of spring rods that are attached to a fixed member of the display system.

21. A display system, comprising:

a light valve comprising an array of individually addressable pixels;

a screen attached to and held by a flexible element;

a moving mechanism attached to the screen for moving the screen; and

a set of optical elements for directing light from the light valve onto the screen.

22. The display system of claim 21, wherein the flexible element is an elongated element; wherein the flexible element is rigid along the length; and is flexible in at least a direction perpendicular to the length.

23. The display system of claim 22, wherein the flexible element is an elongated spring rod.

24. The display system of claim 21, wherein the moving mechanism comprises a voice coil comprising a movable member connected to a screen frame that holds the screen.

25. The display system of claim 21, wherein the flexible element has an intrinsic resonant frequency of lower than 7 Hz or higher than 30 Hz.