Patent Abstract:
A light-emitting apparatus, for enabling a beam of light to be projected on a desired target located a distance away to project the beam on the desired target without any or substantially any undesired movement. The apparatus may include a housing, a light generating device located within the housing and operable to generate a beam of light, a sensing device or devices for sensing an undesired action of the housing, a control circuit operable to provide a control signal corresponding to the sensed undesired action, and a drive device operable to counter act all or at least some of the undesired action of said housing in accordance with said control signal. The sensing device or devices may be one or more gyroscopes, accelerometers or other such devices.

Full Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation-in-part of U.S. patent application Ser. No. 11/315,906, filed Dec. 22, 2005, entitled Motion-Compensating Light-Emitting Apparatus, which in turn is a continuation-in-part of U.S. patent application Ser. No. 11/022,215, now U.S. Pat. No. 7,312,863, filed Dec. 23, 2004, entitled Motion-Compensating Light-Emitting Apparatus, all of which are incorporated by reference herein. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates generally to a system for maintaining a beam of electromagnetic radiation, such as visible light, pointed in a particular direction, despite unwanted movement of the device emitting the beam with respect to an inertial frame of reference. 
       BACKGROUND OF THE INVENTION 
       [0003]    The present invention relates to light-emitting devices and particularly to those devices intended to produce a beam in a selected direction such as toward a target of interest. The invention provides motion-compensation technology suitable for use with such light-emitting devices, which may dampen and/or substantially eliminate the effect of unintentional motion, vibration, or movements, such as angular and/or translational movements, caused by mechanical vibrations, hand tremors, and so forth. 
         [0004]    Light-emitting devices, such as laser diode devices, are used in a variety of consumer, computer, business, medical, scientific, military, outdoor, telecommunication and industrial products, including but not limited to compact disk (CD) players and computer CD-ROM drives, digital video disk (DVD) players and DVD-ROM drives, laser printers, laser pointers, barcode scanners, measurement devices, rangefinders, scopes, industrial material processing devices, marking and cutting systems, medical equipment, fiber optic transmission systems, satellite communications, and digital printing presses. Many of these applications require precision accuracy for successful implementation. However, conventional light-emitting devices may be affected by unintentional angular and/or translational movements (e.g., fine vibrations from the machine in which a laser is encased, fine tremors from a shaking hand holding a laser, etc.) and, as a result, generate an unsteady column of light—producing an effect that may cause inferior performance. 
         [0005]    An example of the above mentioned effect will now be described with reference to a laser pointer. Fine tremors of the human hand, when holding even a lightweight laser pointer (or other pointing device), have been measured at a frequency range of 1 to 5 Hz. These unwanted vibrations are often amplified when the person maneuvering the device is nervous. The resulting deviation of the projected spot from the intended target point to the actual point is proportional to the distance from the pointing device to the target object (e.g., a point on a screen). This deviation may be approximately equal to the product of the sine or the tangent of the angle and the distance to the projected spot. In other words, for small angular movements (such as less than 10 degrees), the movement of the projected spot is approximately equal to the product of the distance to the target and the angle of the movement (in radians). For instance, small angular movements of +/−1 degree of a laser pointing device may result in movements of approximately +/−2 cm of the projected spot on a target 1 meter away; and, these angular movements will result in a 10-fold larger projected spot movement (approximately +/−20 cm) for a target 10 meters away (which may be typical of large lecture halls). In contrast to angular movements, translational movements (sideways movements of the hand) are not amplified by the distance from the light-emitting device to the target object. That is, if the hand holding a laser pointer is moved sideways by 1 cm, the spot on the target is also moved sideways by 1 cm irrespective of how far the target is from the hand. 
       BRIEF SUMMARY OF THE INVENTION 
       [0006]    The present invention provides a motion-compensated, light-emitting apparatus which enables a steady beam of light to be projected onto a desired target even if subjected to undesired unsteady conditions by automatically redirecting or compensating for unintentional, off-target angular and/or translational movements. The present apparatus may use miniature gyroscopes and/or accelerometers and/or other motion sensing type devices and an optical system including light-refracting elements arranged within the apparatus. In a preferred embodiment of the present invention, a motion-compensating light-emitting device is provided which utilizes a mirror mounted on a cantilever composed of an aluminum and Lead Zirconium Titanate (PZT) metal sandwich. In a preferred embodiment, the mirror, positioned by the cantilever, deflects the light beam to compensate for the unwanted tremor based on the angular rates and/or translational motion measured by two or more motion sensors. 
         [0007]    In an alternate embodiment of the present invention, a motion-compensated, light-emitting device utilizes a micro mirror in a two axis Micro-Electronic Mechanical System (MEMS)-based, gimbal-less scanning mirror device. In a preferred embodiment, a commercially available MEMS, made entirely of monolithic single-crystal silicon in a single miniature package, changes a mirror angle in two deflection axes. When an electric field is applied to the preferred two axis MEMS, the mirror surface tilts an amount that is proportional to the applied voltage to stabilize the direction of the emitted light beam. 
         [0008]    In an alternate embodiment of the present invention a motion compensated, light-emitting device is provided that displays a variety of stabilized-rasterized and stabilized-vector graphics as well as stabilized multi-frame animations at arbitrary refresh rates. The system is highly adaptable to projection onto various surfaces and in a variety of applications, including projection onto specially-coated transparent surfaces. Due to the low power consumption and vibration stabilized output of this device, the system preferably is miniaturized, highly portable and fully mobile when used with a laptop small computer. The computer may project different letters, symbols, or graphics or other static or moving images that can change and evolve over time. The system preferably includes a two axis MEMS micro mirror. The signals providing the desired rasterized or vector graphics are added to the vibration stabilization signals, and unwanted movement is reduced or eliminated in the resulting projection. 
         [0009]    In an alternate embodiment of the present invention, a motion-compensated, light-emitting device displays full color, high-quality images that remain in focus at all distances using holographic laser projection technology. The term “holographic” refers not to the projected image, but to the method of projection. A diffraction pattern of the desired 2D image, calculated using holographic algorithms, is displayed on a phase-modulating Liquid Crystal on Silicon (LCOS) microdisplay attached to a two axis MEMS micro mirror. When illuminated by coherent laser light, the desired image is projected on various surfaces without distortion by the micro-tremors imposed on the projection system. 
         [0010]    Rather than blocking light, a phase-modulating LCOS microdisplay mounted on the MEMS micro mirror steers light to exactly where it is needed, making the system highly efficient. Unlike conventional projection systems, a projection lens is not needed. Instead, a demagnification lens pair expands the diffracted image from the microdisplay, producing an ultra-wide throw angle, greater than 100°. The projected images are in focus at all distances from the projector, eliminating the need for focus control. 
         [0011]    The diffractive method of projection naturally lends itself to miniaturization and low cost implementation, allowing images to be projected onto curved and angled surfaces without distortion. In addition, the system is highly tolerant of microdisplay pixel failure—essential in safety critical applications in markets such as automotive. 
         [0012]    In an alternate embodiment of the present invention a motion-compensated, light-emitting device stores the exact orientation of the laser or projection system for later retrieval, derived from a location determination system, a range to target determination system and information from motion detection devices such as accelerometers under user control. The system automatically maintains a light beam emitted from the device in the exact orientation, as stored. In addition, the system may store several orientations, and the system can reorient the light beam in sequential, round-robin fashion. With sufficient displacement of the compensating mirrors, the system can be moved from its location, and if the targets are far enough away, the system can maintain the orientation of the light beam at the marked targets. In addition, by adding some simple modulation to the laser light beams the beams can be turned off when not actually pointing at memorized locations, thus maintaining illumination only at the desired locations that were previously set in memory. 
         [0013]    In one aspect, the present invention is directed to a light-emitting apparatus comprising: a light beam generator that emits a light beam; a device that produces a first signal indicating motion of the generator; an integrator that integrates the first signal to produce a second signal indicating movement of the light beam generator; and a light diverting device mounted to an electronically adjustable cantilever; wherein the second signal is applied to the cantilever so that the light beam projects substantially in a particular direction. 
         [0014]    In another aspect of the present invention, the cantilever comprises a first layer of ceramic and a second layer of lead zirconium titanate. 
         [0015]    In another aspect of the present invention, the apparatus further comprises first and second angular rate-sensing devices; and first and second cantilevers; wherein the first angular rate-sensing device measures pitch angular velocity and the second angular rate-sensing device measures yaw angular velocity, the integrator integrates signals produced by both first and second signals and the integrated signals are applied to the first and second cantilevers, respectively. 
         [0016]    In another aspect of the present invention, the apparatus further comprises a graphics generator that generates a third signal; and a signal combiner that combines the first and second signals with the third signal; wherein the third signal, applied to the cantilevers, diverts the light beam to project an image. 
         [0017]    In another aspect of the present invention, the apparatus further comprises a user interface that selects a current orientation of the generator; and a memory that stores the current orientation; wherein the apparatus maintains the light beam projected at the current orientation. 
         [0018]    In another aspect of the present invention, the apparatus further comprises a measurement device that generates a third signal representative of a measured orientation and wherein the memory further stores the measured orientation. 
         [0019]    In another aspect of the present invention, the measurement device comprises a digital magnetometer and the measured orientation is azimuth. 
         [0020]    In another aspect of the present invention, the memory stores more than one orientation and the apparatus directs the beam in a sequence of one or more directions from the orientations stored in the memory. 
         [0021]    In another aspect of the present invention, the light diverting device comprises a mirror. 
         [0022]    In another aspect of the present invention, the light diverting device comprises a lens. 
         [0023]    In another aspect of the present invention, the integrator integrates the first signal to produce a second signal that indicates an angular and translational movement of the light beam generator; and; wherein the second signal is applied to the cantilever so that angular and translational movement is substantially eliminated. 
         [0024]    In another aspect, the present invention is directed to a light-emitting apparatus comprising: a light beam generator that emits a light beam; a motion-sensing device that produces a first signal indicating movement of the generator; an integrator that integrates the first signal to produce a second signal indicating a movement of the light beam generator; and a micro electronic mechanical system that positions a light diverting device; wherein the second signal is applied to the micro electronic mechanical system to project the beam substantially in a particular direction. 
         [0025]    In another aspect of the present invention, the light diverting device comprises a mirror. 
         [0026]    In another aspect of the present invention, the light diverting device comprises a lens. 
         [0027]    In another aspect of the present invention, the apparatus further comprises first and second angular rate-sensing devices; wherein the first angular rate-sensing device measures pitch angular velocity and the second angular rate-sensing device measures yaw angular velocity, the integrator integrates signals produced by both first and second signals and the integrated signals are applied to the micro electronic mechanical system. 
         [0028]    In another aspect of the present invention, the apparatus further comprises a graphics generator that generates a third signal; and a signal combiner that combines the first and second signals with the third signal; wherein the third signal, applied to the micro electronic mechanical system, diverts the light beam to project an image. 
         [0029]    In another aspect of the present invention, the integrator integrates the first signal to produce a second signal that indicates an angular and translational movement of the light beam generator; and; wherein the second signal is applied to the micro electronic mechanical system to project the beam so that angular and translational movement is substantially eliminated. 
         [0030]    In another aspect of the present invention, the apparatus further comprises a user interface that selects a current orientation of the generator; and a memory that stores the current orientation; wherein the apparatus maintains the light beam projected at the current orientation. 
         [0031]    In another aspect of the present invention, the apparatus further comprises a measurement device that generates a third signal representative of a measured orientation and wherein the memory further stores the measured orientation. 
         [0032]    In another aspect of the present invention, the measurement device comprises a digital magnetometer and the measured orientation is azimuth. 
         [0033]    In another aspect of the present invention, the memory stores more than one orientation and the apparatus directs the beam in a sequence of one or more directions from the orientations stored in the memory. 
         [0034]    In another aspect of the present invention, the apparatus further comprises a plurality of colored lasers; and a laser collimating device that combines the plurality of colored lasers into a single beam; wherein the light beam generator comprises the plurality of colored lasers; and wherein the light diverting device comprises a micro display that generates an image from the single beam. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0035]      FIG. 1  is a diagram of a motion-compensating light-emitting apparatus according to an embodiment of the present invention; 
           [0036]      FIG. 2  is a diagram of the motion-compensating light-emitting apparatus of  FIG. 1  to which reference will be made in explaining the operation thereof; 
           [0037]      FIG. 3  is a diagram of a motion-compensating light-emitting apparatus according to another embodiment of the present invention; 
           [0038]      FIG. 4  is a diagram of the motion-compensating light-emitting apparatus of  FIG. 3  to which reference will be made in explaining the operation thereof; 
           [0039]      FIG. 5  is a diagram to which reference will be made in explaining the operation of the present apparatus; 
           [0040]      FIG. 6  is a diagram of a motion-compensating light-emitting apparatus according to another embodiment of the present invention; 
           [0041]      FIG. 7  is a block diagram of a motion-compensated, laser diode pointer utilizing cantilevers; 
           [0042]      FIG. 8  is a block diagram of a motion-compensated light-emitting apparatus according to another embodiment of the present invention comprising a two axis MEMS based micro mirror; 
           [0043]      FIG. 9  is a block diagram illustrating a motion-compensated light-emitting device for displaying a variety of stabilized rasterized and stabilized vector graphics as well as stabilized multi-frame animations at arbitrary refresh rates; 
           [0044]      FIG. 10  is a block diagram of a motion-compensated, holographic laser projector; and 
           [0045]      FIG. 11  is a block diagram of a motion and position compensated laser pointer. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0046]      FIG. 1  is a diagram of a laser diode pointer  100  which includes vibration or motion compensation circuitry in accordance with an embodiment of the invention. A visible laser diode  110  may be used as the light source. There are several ways of implementing the vibration compensation scheme. In accordance with an embodiment of the invention, two angular velocity sensors (gyros)  120  and  125  are aligned in orthogonal directions and used to measure the angular movements in the pitch and yaw axis (also referred to as the X and Y axis). In a preferred embodiment, the two miniature gyroscopes comprise, for example, a micro electro mechanical system (“MEMS”), such as model ADXRS150 manufactured by Analog Devices, Inc. These gyros may have a relatively small volume (such as less than 0.15 cm 3 ), low weight (such as less than 500 mg), and small size (such as 7 mm×7 mm×3 mm or less). In another embodiment of the present invention, a motion-compensating light-emitting device is provided which utilizes two or three miniature accelerometers (for example, MEMS, such as model ADXL203 manufactured by Analog Devices, Inc.) arranged to measure acceleration and changes of the gravity vector (changes in acceleration) or relative tilts with respect to the vertical axis in two orthogonal directions (i.e., yaw and pitch) and to obtain from this information the relative vertical and horizontal angular movements and translational movements. These accelerometers may have a relatively small volume 0.05 cm 3  (with dimensions of 0.5 cm×0.5 cm×0.2 cm). Additionally, the accelerometers may be provided in a hermetically sealed package. 
         [0047]    The output of gyros  120  and  125  are amplified by two amplifiers  131  and  132  respectively and/or sampled by an A/D converter  133  in anti-vibration control circuit  130 . The sampled signal may be passed to a band frequency filter  134  where the portion of the signal associated with the rapid, unwanted angular motions of the pointer in this example, typically that portion between 1 and 5 Hz, is extracted. Although a band frequency filter having a range of 1 to 5 Hz is described, a variable frequency filter may be used to set the desired band of frequencies. The range of frequencies may be adjusted by utilizing an adjustment type device such as a variable resistor or digital switches. 
         [0048]    The filtered signal may then be integrated by an integrating processor circuit  135 . Because gyros  120  and  125  measure angular velocity, the signal received by integrating processor circuit  135  may be integrated to obtain angular information from which an angular difference may be obtained. Although the embodiment of  FIG. 1  utilizes gyros  120  and  125  that measure angular velocity, gyros  120  and  125  may measure an angular difference. In such instance, integrating processor circuit  135  may not be included in the anti-vibration control circuit  130 . 
         [0049]    The integrated rate output or angular difference (proportional to the angle of the unwanted angular motion) may be conditioned by a correction amount normalization circuit  136  (which may include amplifying the signal by a necessary or predetermined amount) and supplied as an input for motors  140  and  150 , which may be connected to a movable lens  160  (which may be located between the laser diode  110  and a focusing lens  170 ). Movable lens  160  and focusing lens  170  may each be constructed from one or more convex lenses and/or concave lenses, or a combination of convex and concave lenses, or one or more convex/concave type lenses, or any combination thereof. The signals may be conditioned so that the feedback loops provide an input signal to the motion correction mechanisms such that the resulting circuits are stable in the region of interest. The conditioning may include adjusting the gain of the signal as well as adjusting for the null of the circuit and the zero offset of the gyros. Thus, if the integrated rate output measured is equal to 1 degree, the amplified signal has to equal a voltage (or current) that will produce a motor movement required to move the compensating lens for a one degree of motion. 
         [0050]    The anti-vibration control circuit  130  may be part of a microprocessor or microcomputer, or could be constructed out of individual analog and digital elements depending on the cost, size and power consumption of each implementation. Additionally, an on/off switch may be provided in laser diode pointer  100  which may enable a user to turn off the anti-vibration control circuit if the user does not want to use the motion compensating function. 
         [0051]      FIG. 2  is a diagram of a laser diode pointer  100  when it is tilted down. The gyros  120  and  125  may measure the angular velocity of the tilt, and their output signals (which may be in analog form) are proportional to the angular rate of the motion. Such signals may then be amplified, digitized and passed to the band pass frequency filter  134 . The band frequency filter  134  may extract the portion of the signal(s) associated with rapid unwanted angular motion (e.g. unwanted hand tremors which may be in the 1 to 5 Hz range). The filtered signal may then be integrated by the integrating processor circuit  135 . The normalizing and conditioning circuit  136  may receive the integrated signal and, in accordance therewith, may generate a voltage or current signal having a value or magnitude corresponding to the necessary compensation, and may cause the same to be supplied to compensating element(s) (such as motors  140  and  150 ). In response thereto, the motors  140  and  150  may cause the corrective lens  160  to move in a direction such that an exiting beam continues to exit the laser pointer  100  in a horizontal or a substantially horizontal direction. Without the movement of this corrective movable lens  160  the beam would exit at a downward angle. The motors  140  and  150  may be an electro-motor, an electromagnetic motor, a piezo-electric motor or any other type of actuator suited for this application. 
         [0052]    Although not shown in this diagram, laser pointer  100  (which includes the gyros and the anti-vibration circuit) may be powered by a power source such as two 1.5V batteries connected in series as used for ordinary laser pointers. To save on power usage, the motion-compensation technology may be activated only upon activation of the laser pointer. 
         [0053]    Although  FIG. 2  depicts a laser diode pointer  100  tilted on one axis and its resulting compensation, tilting on the other axis would be compensated similarly (and independently) and is not illustrated in order to keep the drawings simple and easy to follow. 
         [0054]    In another embodiment of the invention, and as shown in  FIG. 3 , a laser diode pointer  200  may use a movable bellows  210  that may be filled with a high refractive index solution or material  220  instead of corrective movable lens  160 . The refractive index of the high refractive index solution or material  220  may be approximately 1.33 or higher. The high refractive index solution or material  220  may be stored between two sheets of glass  230  and  240  such that the portion of the high refractive index solution in the path of the optical beam may be adjusted (by squeezing or spreading the bellows) based on the angular rates measured by the two angular velocity sensors or gyros  120  and  125 . Instead of moving an optical lens to change the direction of the exiting beam the bellows filled with high refractive index solution may be contracted on one end and expanded on the other end so as to bend the exiting light beam in a direction opposite to the unwanted motion. 
         [0055]      FIG. 4  shows how such a change in the thickness or arrangement of the bellows may cause the beam to bend so as to compensate for the unwanted motion. As in the previously described laser pointer having a movable lens, the laser pointer  200  may be powered by a power source such as a number of batteries arranged in a predetermined manner. Additionally,  FIGS. 3 and 4  indicate how motion in the pitch or X axis is compensated; however, motion in the yaw or Y axis may be compensated similarly (and independently) and is not illustrated in order to keep the drawings simple and easy to follow. 
         [0056]      FIG. 5  is a flow chart describing how a laser pointer in accordance with an embodiment of the present invention compensates for unwanted motion. The process starts in step S 100  where the laser pointer is turned on by pressing a button or the like. During operation of the laser pointer, a sensing means, which may include gyros or accelerometers or a combination thereof, measure movement and output a signal which may be processed by the anti-vibration control circuit. Such processing may include the analog to digital conversion performed by the A/D converter  133 . Processing may then proceed to step S 120  wherein the signal may be supplied through a band pass filter so as to effectively detect and extract signals corresponding to the unwanted motion of the laser pointer (unwanted motion may be in the 1 to 5 Hz range). If the sensing means does not detect unwanted motion, the method may proceed to step S 130  where the correcting lens or bellows is not moved and the beam exits the laser pointer with out any redirection. If there is unwanted motion detected by the sensing means, the method proceeds to step S 140  where the processed signal may be integrated and/or amplified. A voltage or current corresponding to the processed and/or amplified signal may be applied to the drive motors in step S 150 , which in turn, may move the prism or the bellows in step S 160 . In step S 170 , the beam may be redirected in the direction opposite the direction of the hand tremor. 
         [0057]      FIG. 6  is a diagram of another embodiment of the laser diode pointer  300  wherein accelerometers are utilized instead of gyroscopes. Three angular velocity and/or translational motion sensors (accelerometers)  310 ,  320 , and  330 , which may be aligned in orthogonal directions, may be used to measure the angular and/or translational movements in the pitch, yaw and roll axis (also referred to as the X, Y and Z axis) respectively. The output of accelerometers  310 ,  320 , and  330  may be respectively amplified by three amplifiers  340 ,  350 , and  360 , and then sampled by A/D converter  133  in the anti-vibration control circuit  330 . The portion of the signal associated with rapid unwanted angular and/or translational motions of the pointer (e.g., an unwanted hand tremor in the 1-5 Hz range) may be extracted by band pass filter  134  and integrated by integrating processor circuit  135 . Movements (tilts) of the laser pointer may be measured by comparing the measured acceleration to a gravity vector (g acceleration) as the laser pointer is tilting and/or computing the motions from the three orthogonal measurements of the acceleration. 
         [0058]    The computed integrated rate output (proportional to the angle of the unwanted angular and/or translational motion) may be conditioned (which may include amplifying the signal by a necessary or predetermined amount) and/or used as the input for motor(s) that may be coupled to movable lens  160  located between the laser diode  110  and the focusing lens  170 . The anti-vibration circuit  330  may be included in a microprocessor or microcomputer or may be constructed out of individual analog and/or digital elements depending on the cost, size and power consumption requirements. 
         [0059]      FIG. 7  is a block diagram of another embodiment of the present invention. A motion-compensated, laser diode pointer illustrated in  FIG. 7  comprises a laser emitting diode  110 , motion sensors  120 ,  125 , signal amplifiers  131 ,  132 , an A/D converter  133 , high pass filter  134 , integrating circuit  135 , normalization circuit  136 , pitch drive  140 , yaw drive  150 , and mirrors  310  and  320  mounted on cantilevers  350  and  360 . Preferably, Bimorph ceramic cantilever strips  350  and  360  comprise Lead Zirconium Titanate (PZT)-metal sandwich strips, or other piezoelectric materials. Cantilevers  350 ,  360  may be composed of single or multiple elements. Mirrors  310 ,  320  may be moved by various other means in addition to bimorph ceramic strips of the type used for this application. 
         [0060]    In operation, the function of laser emitting diode  110 , motion sensors  120 ,  125 , signal amplifiers  131 ,  132 , an A/D converter  133 , high pass filter  134 , integrating circuit  135 , normalization circuit  136 , pitch drive  140  and yaw drive  150  are described above and will not be repeated here. Voltage generated by these components are applied to cantilevers  350 ,  360 , causing them to bend and thus to change the angle of mounted mirrors  310 ,  320 . The voltage applied to cantilevers  350 ,  360  deflects each cantilever proportional to the magnitude of the voltage applied. Mirrors  310  and  320  at the end of cantilevers  350 ,  360  deflect the laser beam. A mirror deflection of one degree of angle will deflect light by a two degree of angle deflection—one degree of deflection for the incident beam and one degree of deflection for the reflected beam. Thus, moving a mirror is twice as efficient as moving a lens. The amount of deflection may be adjusted based on the angular rates measured by the two motion sensors  120  and  125 . Preferably, motion sensors  120 ,  125  are angular velocity sensors or gyros. 
         [0061]    In an alternate embodiment (not illustrated), a set of three to six accelerometers are connected to the body of the laser pointer to measure the unwanted vibrations by measuring the changes of the gravity vector during the unwanted vibration of the laser pointer. Three accelerometers would be the minimum number required and six accelerometers would provide additional accuracy for determining the amount of unwanted vibration present. 
         [0062]      FIG. 8  is a block diagram of a motion-compensated light-emitting apparatus according to another embodiment of the present invention comprising a two axis MEMS based micro mirror. As illustrated in  FIG. 8 , the system includes a two axis MEMS micro mirror  410 , in addition to the aforementioned components laser emitting diode  110 , motion sensors  120 ,  125 , signal amplifiers  131 ,  132 , an A/D converter  133 , high pass filter  134 , integrating circuit  135 , normalization circuit  136 , pitch drive  140 , yaw drive  150 . Two axis MEMS micro mirror  410  is preferably a commercially available unit, such as from Mirrorcle Technologies Inc., type SO308. The mirror changes angle with respect to the package in a similar manner as large scale galvanometer based optical scanners, except that MEMS micro mirror  410  requires several orders of magnitude less driving power. In addition, micro mirrors devices that change in both deflection axes are readily available in a single miniature device that is very compact, typically smaller than 8 mm×14 mm×2 mm. 
         [0063]    In operation, the function of laser emitting diode  110 , motion sensors  120 ,  125 , signal amplifiers  131 ,  132 , an A/D converter  133 , high pass filter  134 , integrating circuit  135 , normalization circuit  136 , pitch drive  140  and yaw drive  150  are described above and will not be repeated here. In this embodiment, the angle of mirror  410  can be controlled independently in each of two axes (X and Y) by the applied voltage from independent mirror drives  140  and  150 . Mirror  410  will deflect the beam proportional to the applied voltage in each axis. The amount of deflection may be adjusted based on the angular rates measured by the motion sensors  120  and  125 . A voltage applied to the MEMS micro mirror tilts to change the angle of mirror  410 . As described above, moving a mirror is twice as efficient as moving a lens. Thus, with a mirror deflection of one degree of angle, the light is deflected two degrees—one degree of deflection for the incident beam and one degree of deflection for the reflected beam. 
         [0064]    In an alternate embodiment (not illustrated), a set of three to six accelerometers are connected to the body of the laser pointer to measure the unwanted vibrations by measuring the changes of the gravity vector during the unwanted vibration of the laser pointer. Three accelerometers would be the minimum number required and six accelerometers would provide additional accuracy for determining the amount of unwanted vibration present. 
         [0065]      FIG. 9  is a block diagram illustrating a motion-compensated light-emitting device for displaying a variety of stabilized rasterized and stabilized vector graphics as well as stabilized multi-frame animations at arbitrary refresh rates. As illustrated in  FIG. 9 , the system comprises laser emitting diode  110 , motion sensors  120 ,  125 , signal amplifiers  131 ,  132 , an A/D converter  133 , high pass filter  134 , integrating circuit  135 , normalization circuit  136 , pitch drive  140 , yaw drive  150  and a two axis MEMS micro mirror  410 , all of which are described above. In addition, the system comprises a signal conditioning filtering and voltage control device  420 , a computer or microprocessor  430 , a self contained vector graphics or raster graphics generator  440 , a signal conditioning, filtering and voltage control unit  450  and a voltage adder  460 , which are used to generate a projected image  470 , for example, a symbol, letter, or figure. 
         [0066]    Image  470  is represented by a low level signal that is transmitted to a signal conditioning, filtering and voltage control device  420  by computer  430 . Device  420  sends its output signal to a voltage adder  460  that combines this output signal with the motion compensation signal from normalization circuit  136 , to stabilize the projection of image  470 . In another embodiment, a self contained vector graphics or raster graphics generator  440  can be self contained within the proposed laser pointer system. The signal output of generator  440  is sent to a signal conditioning, filtering and voltage control unit  450  to ensure the proper dimensioning of the projected image  470 . Signal conditioning, filtering, voltage control system  450  sends an output signal to the voltage adder/combiner  460 . After the voltages for the vibration stabilization  136  and the generation of the image  470  have been combined, the signals are provided as input to the respective X and Y axis mirror drive units  140  and  150 . By superposition, the resulting system projects the desired rasterised or vector graphic with the motion reduction signal in a manner that would not be possible without the vibration stabilization portion as often the resulting projection would be unrecognizable or unreadable because of laser beam jitter. 
         [0067]    The system is highly adaptable to projection onto various surfaces and in a variety of applications, including projection onto specially-coated transparent surfaces. Due to the low power consumption and vibration stabilized output of this device, the system is highly portable, especially mobile when used with a laptop small computer. A computer can be used for a generator  440  to project different letters, symbols, or graphics or other static or moving images  470  that can change and evolve over time as well as be a function of the material that is presented. 
         [0068]    In an alternate embodiment (not illustrated), a set of three to six accelerometers are connected to the body of the laser pointer to measure the unwanted vibrations by measuring the changes of the gravity vector during the unwanted vibration of the laser pointer. Three accelerometers would be the minimum number required and six accelerometers would provide additional accuracy for determining the amount of unwanted vibration present. 
         [0069]      FIG. 10  is a block diagram of a motion-compensated, holographic laser projector. As illustrated in  FIG. 10 , a motion-compensated projection device is provided comprising motion sensors  120 ,  125 , signal amplifiers  131 ,  132 , an A/D converter  133 , high pass filter  134 , integrating circuit  135 , normalization circuit  136 , pitch drive  140 , yaw drive  150  and a two axis MEMS micro mirror  410 , all of which are described above. In addition, the system comprises lasers  500 , collimating lenses  510 , mirrors  520 , demagnification lenses  530 , projected display  540  and micro display  550 . 
         [0070]    The motion-compensated projection device displays full color, high-quality images that remain in focus at all distances using holographic laser projection technology. The term “holographic” refers not to the projected image, but to the method of projection. Three lasers of magenta, blue and green color  500  each generate a laser beam that is collimated by individual lenses  510 . The beams are reflected and combined into a single beam by three mirrors  520 . The combined beam is then reflected off micro display  550 . A diffraction pattern of the desired 2D image, calculated using holographic algorithms, is displayed on this phase-modulating Liquid Crystal on Silicon (LCOS) micro display  550  that is attached on top of a two axis MEMS micro minor  410 . When illuminated by coherent laser light, the desired image  540  is projected on various surfaces without being distorted by the micro-tremors of the projection system. 
         [0071]    Rather than blocking light, the phase-modulating LCOS micro display  550  mounted on MEMS micro minor  410  steers the light to exactly where it is needed, making the system highly efficient. By combining the holographic laser projection technology with the vibration reduction technique a projection system is created that projects images without also projecting the various vibrations and tremors of the projection system or the support structure of the projection system. The resulting system projects the desired image in a manner that would not be possible without the vibration stabilization portion as often the resulting projection would be of much lower quality, unrecognizable or unreadable because of laser beam jitter, or jitter in all elements used to project the image on the desired surface. 
         [0072]    Unlike conventional projection systems, this type of technology does not require a projection lens. Instead, a demagnification lens pair expands the diffracted image from the micro display, producing an ultra-wide throw angle greater than 100°. The projected images are in focus at all distances from the projector, eliminating the need for a focus control. The diffractive method of projection naturally lends itself to miniaturization and low cost implementation. It allows images to be projected onto curved and angled surfaces without distortion, and is highly tolerant to micro display pixel failure—essential in safety critical applications in markets such as automotive. 
         [0073]    In an alternate embodiment (not illustrated), a set of three to six accelerometers are connected to the body of the laser pointer to measure the unwanted vibrations by measuring the changes of the gravity vector during the unwanted vibration of the laser pointer. Three accelerometers would be the minimum number required and six accelerometers would provide additional accuracy for determining the amount of unwanted vibration present. 
         [0074]      FIG. 11  is a block diagram of a motion and position compensated laser pointer. As illustrated in  FIG. 11 , the system comprises laser emitting diode  110 , signal amplifiers  131 ,  132 , an A/D converter  133 , high pass filter  134 , integrating circuit  135 , normalization circuit  136 , pitch drive  140 , yaw drive  150  and a two axis MEMS micro mirror  410 , all of which are described above. In a preferred embodiment, the system further comprises a memory  560 , a computer  570 , X and Y accelerometers  580  and  590 , a digital magnetometer  595 , a location indicator  596  and a range indicator  597 . 
         [0075]    The motion-compensated projection device stores in memory  560  the orientation of the laser or projection system at times directed by the user. For example, the user may mark a target by pressing a button (not shown). Signals from two angular position and/or translational motion sensors or accelerometers, in the X and Y orientation  580  and  590  and a digital magnetometer  595  (for azimuth orientation) indicate the orientation of the laser pointer when the user so indicates. In addition, location indicator  596  and range indicator  597  provide position and range to target information that is stored in memory  560  for later retrieval. Memory  560  is accessed by computer  570 . In an alternative method of operation, the desired positions could be downloaded from computer  570  into memory  560 . The system maintains the laser pointed in the marked orientation. In addition, several points can be marked in sequence, and the laser can scan and point at them in a round-robin fashion. 
         [0076]    In an alternate embodiment (not illustrated), a set of three to six accelerometers are connected to the body of the laser pointer to measure the unwanted vibrations by measuring the changes of the gravity vector during the unwanted vibration of the laser pointer. Three accelerometers would be the minimum number required and six accelerometers would provide additional accuracy for determining the amount of unwanted vibration present. 
         [0077]    Having thus described at least illustrative embodiments of the invention, various modifications and improvements will readily occur to those skilled in the art and are intended to be within the scope of the invention. Accordingly, the foregoing description is by way of example only and is not intended as limiting. 
         [0078]    Although the above embodiments describe laser pointers that may utilize specific combinations of gyroscopes or accelerometers, the present invention is not so limited. For example, the present invention may also utilize other types of motion sensing devices or may utilize a different number of gyroscopes or accelerometers or may utilize a combination of gyroscopes and accelerometers to sense unwanted motion. In addition, although a “light beam” is recited, the invention shall not be limited to a ray of visible light, but shall also encompass other forms of electromagnetic radiation that can be reflected or refracted, as is well known in the art, such as infrared, ultraviolet, or even x-ray or other non-visible radiation. Although preferred embodiments of the present invention and modifications thereof have been described in detail herein, it is to be understood that this invention is not limited to those precise embodiments and modifications, and that other modifications and variations may be effected by one skilled in the art without departing from the spirit and scope of the invention as defined by the appended claims.

Technology Classification (CPC): 6