Patent Publication Number: US-2013229500-A1

Title: Methods and apparatus for upgrading a projector to display three-dimensional content

Description:
BACKGROUND 
     For decades, two-dimensional (2D) display screens have been used to display video content to viewers. While such screens have managed to evolve over the years, a current direction of interest in display screens is towards three-dimensional (3D) display screens. With such interest, the development of ways to upgrade a projector to display three-dimensional content is also of interest. 
     SUMMARY 
     These and other drawbacks and disadvantages of the prior art are addressed by the present principles, which are directed to methods and apparatus for upgrading a projector to display three-dimensional (3D) content. 
     According to one aspect, an apparatus is provided for upgrading a projector having a two-dimensional projector lens to display three-dimensional content. The apparatus includes a circular polarized filter having at least two polarized zones, and a motor having a shaft on which is mounted the circular polarized filter. The apparatus further includes at least one light sensor disposed in front of the projector lens for providing a spatial control output signal and a temporal control output signal. The apparatus further includes a processor for controlling a speed at which the circular polarized filter is rotated around the shaft of the motor responsive to information determined from the spatial control output signal and the temporal control output signal, such that the circular polarized filter is automatically adjusted to spin so as to respectively place an appropriate one of the two polarized zones of the circular polarized filter in front of an applicable frame of the video sequence to obtain a polarization thereof representative of the three-dimensional content. 
     According to another aspect, a method is provided for upgrading a projector having a two-dimensional projector lens to display three-dimensional content. The method includes providing a circular polarized filter having at least two polarized zones, and a motor having a shaft on which is mounted the circular polarized filter. The method further includes providing a spatial control output signal and a temporal control output signal. The method also includes controlling a speed at which the circular polarized filter is rotated around the shaft of the motor responsive to information determined from the spatial control output signal and the temporal control output signal, such that the circular polarized filter is automatically adjusted to spin so as to respectively place an appropriate one of the two polarized zones of the circular polarized filter in front of an applicable frame of the video sequence to obtain a polarization thereof representative of the three-dimensional content. 
     According to yet another aspect, an apparatus is provided for upgrading a projector having a two-dimensional projector lens to display three-dimensional content. The apparatus includes a circular polarized filter having at least two polarized zones, and a motor having a shaft on which is mounted the circular polarized filter. The apparatus further includes a user input device for receiving a user input and controlling a speed at which the circular polarized filter is rotated around the shaft of the motor responsive to the user input. The circular polarized filter is spun responsive to the user input so as to respectively place an appropriate one of the two polarized zones of the circular polarized filter in front of an applicable frame of the video sequence to obtain a polarization thereof representative of the three-dimensional content. 
     According to still another aspect, a method is provided for upgrading a projector having a two-dimensional projector lens to display three-dimensional content. The method includes providing a circular polarized filter having at least two polarized zones, and a motor having a shaft on which is mounted the circular polarized filter. The method further includes receiving a user input and controlling a speed at which the circular polarized filter is rotated around the shaft of the motor responsive to the user input. The circular polarized filter is spun responsive to the user input so as to respectively place an appropriate one of the two polarized zones of the circular polarized filter in front of an applicable frame of the video sequence to obtain a polarization thereof representative of the three-dimensional content. 
     These and other aspects, features and advantages of the present principles will become apparent from the following detailed description of exemplary embodiments, which is to be read in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present principles may be better understood in accordance with the following exemplary figures, in which: 
         FIG. 1  is a block diagram showing an exemplary apparatus for upgrading a projector to display three-dimensional content, in accordance with an embodiment; 
         FIG. 2  is a flow diagram showing an exemplary method for upgrading a projector to display three-dimensional content, in accordance with an embodiment; 
         FIG. 3  is a block diagram showing another exemplary apparatus for upgrading a projector to display three-dimensional content, in accordance with an embodiment; and 
         FIG. 4  is a flow diagram showing another exemplary method for upgrading a projector to display three-dimensional content, in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     The present principles are directed to methods and apparatus for upgrading a projector to display three-dimensional (3D) content. The present description illustrates the present principles. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described or shown herein, embody the present principles and are included within its scope. 
     All examples and conditional language recited herein are intended for pedagogical purposes to aid the reader in understanding the present principles and the concepts contributed by the inventor(s) to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. 
     Moreover, all statements herein reciting principles, aspects, and embodiments of the present principles, as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently known equivalents as well as equivalents developed in the future, i.e., any elements developed that perform the same function, regardless of structure. 
     Thus, for example, it will be appreciated by those skilled in the art that the block diagrams presented herein represent conceptual views of illustrative circuitry embodying the present principles. Similarly, it will be appreciated that any flow charts, flow diagrams, state transition diagrams, pseudocode, and the like represent various processes which can be substantially represented in computer readable media and so executed by a computer or processor, whether or not such computer or processor is explicitly shown. 
     The functions of the various elements shown in the figures can be provided through the use of dedicated hardware as well as hardware capable of executing software in association with appropriate software. When provided by a processor, the functions can be provided by a single dedicated processor, by a single shared processor, or by a plurality of individual processors, some of which can be shared. Moreover, explicit use of the term “processor” or “controller” should not be construed to refer exclusively to hardware capable of executing software, and can implicitly include, without limitation, digital signal processor (“DSP”) hardware, read-only memory (“ROM”) for storing software, random access memory (“RAM”), and non-volatile storage. 
     Other hardware, conventional and/or custom, can also be included. Similarly, any switches shown in the figures are conceptual only. Their function can be carried out through the operation of program logic, through dedicated logic, through the interaction of program control and dedicated logic, or even manually, the particular technique being selectable by the implementer as more specifically understood from the context. 
     In the claims hereof, any element expressed as a means for performing a specified function is intended to encompass any way of performing that function including, for example, a) a combination of circuit elements that performs that function or b) software in any form, including, therefore, firmware, microcode or the like, combined with appropriate circuitry for executing that software to perform the function. The present principles as defined by such claims reside in the fact that the functionalities provided by the various recited means are combined and brought together in the manner which the claims call for. It is thus regarded that any means that can provide those functionalities are equivalent to those shown herein. 
     Reference in the specification to “one embodiment” or “an embodiment” of the present principles, as well as other variations thereof, means that a particular feature, structure, characteristic, and so forth described in connection with the embodiment is included in at least one embodiment of the present principles. Thus, the appearances of the phrase “in one embodiment” or “in an embodiment,” as well any other variations, appearing in various places throughout the specification are not necessarily all referring to the same embodiment. 
     It is to be appreciated that the use of any of the following “/”, “and/or”, and “at least one of”, for example, in the cases of “A/B”, “A and/or B” and “at least one of A and B”, is intended to encompass the selection of the first listed option (A) only, or the selection of the second listed option (B) only, or the selection of both options (A and B). As a further example, in the cases of “A, B, and/or C” and “at least one of A, B, and C”, such phrasing is intended to encompass the selection of the first listed option (A) only, or the selection of the second listed option (B) only, or the selection of the third listed option (C) only, or the selection of the first and the second listed options (A and B) only, or the selection of the first and third listed options (A and C) only, or the selection of the second and third listed options (B and C) only, or the selection of all three options (A and B and C). This can be extended, as readily apparent by one of ordinary skill in this and related arts, for as many items listed. 
     The present principles are directed to a method and apparatus for upgrading a two-dimensional (2D) projector to display three-dimensional (3D) content. The REALD 3D technology currently used on movie theaters involves using two polarized filters that are alternated in front of the projector lens synchronously with the frames. Thus, the left and right frames of the three-dimensional content will be polarized with one of the two polarized filters. 
     For example, in one embodiment, a light sensor (i.e., a photoresistor) set in front of a projector lens is considered. By using this sensor and some processing (if required), it can be possible to detect the frequency F and time in which frames are projected. Let us consider a small Direct Current (DC) motor, spinning at the same speed as F. Attached to this motor there is a circular filter, each half with a different polarization. By using another sensor, it is possible to know the instant at which the edge between the two polarized zones of the filter crosses a particular point. The circular filter is placed in front of the projector lens, and the system is automatically adjusted to spin at the proper speed to use one zone of the polarized filter per frame. 
     Turning to  FIG. 1 , an exemplary apparatus for upgrading a projector to display three-dimensional content is indicated generally by the reference numeral  100 . The apparatus  100  includes a first light sensor  110 , a processor  120 , a Direct Current (DC) motor  130 , a circular polarized filter  140 , and a second light sensor  150 . The circular polarized filter  140  is manufactured and/or otherwise provided to have at least two polarized zones thereon, namely at least a first polarized zone  145  and a second polarized zone  146 , with at least one edge  141  separating the at least first and second zones  145  and  146 . 
     The light sensor  110  is set in front and/or in proximity of a projector lens  101 . An output (also interchangeably referred to herein as a “temporal control output signal”) of the light sensor  110  is connected in signal communication with a first input of the processor  120 . The processor  120  determines, based on pre-specified criteria applied to the output of the light sensor  110 , a frequency F and a time at which frames of a particular video sequence are projected during a sequential showing of the particular video sequence. The criteria can include, but is not limited to, information indicative of the presentation (displaying) of a new frame. Such information can include, but is not limited to, one or more new objects being displayed that were not displayed a set time earlier or one or more objects missing that were displayed a set time earlier, where the inclusion or omission can be judged as a new frame. Moreover, reappearing objects (i.e., there one instant, gone a set time later, only to reappear a set time there after) can be used as well to judge the presence of a new frame. Moreover, text, symbols, etc. (collectively referred to as characters herein after) can used to indicate the presence (displaying) of a new frame, where the characters are formatted into a display size that is small (e.g., smaller than the naked eye can see at close range), and the sensor  110  can read the same to determine when a new frame is being displayed. Of course, it is to be appreciated that the preceding criteria is merely illustrative and, thus, other criteria can be used as readily contemplated by one of ordinary skill in this and related arts, given the teachings provided herein. In this way, accurate temporal positioning of an appropriate one of the at least two polarized zones of the filter in front of an appropriate frame of the video sequence can be obtained. Thus, the output signal of the light sensor  110  can be considered a temporal control output signal. 
     The light sensor  150  is also set in front and/or in proximity of a projector lens  101 . An output (also interchangeably referred to herein as a “spatial control output signal”) of the light sensor  150  is connected in signal communication with a second input of the processor  120 . The processor  120  determines a time instant at which the edge  141  between the two polarized zones of the filter crosses a particular point. In this way, accurate spatial positioning of an appropriate one of the at least two polarized zones of the filter in front of an appropriate frame of the video sequence can be obtained. Thus, the output signal of the light sensor  150  can be considered a spatial control output signal. 
     As noted above, the circular polarized filter  140  is manufactured and/or otherwise provided to have at least two polarized zones thereon. The circular polarized filter  140  is attached to an output shaft  131  of the DC motor  130 . An output of the processor  120  is connected in signal communication with a control input of the DC motor  130 . The control input controls the speed at which the shaft  131  of the DC motor spins. The DC motor  130  is configured to spin at a speed equal and/or otherwise corresponding to the frequency F. In this way, the DC motor  130  spins so that the attached circular polarized filter  140  is automatically adjusted to spin at the proper speed which respectively places an appropriate one of the two polarized zones of the circular polarized filter  140  in front of an applicable frame of the video sequence to obtain a desired polarization thereof. 
     Turning to  FIG. 2 , an exemplary method for upgrading a projector to display three-dimensional content is indicated generally by the reference numeral  200 . At step  210 , a processor  120  is provided along with a motor  130  having a shaft  131  on which is mounted a circular polarized filter  140  having at least two polarized zones. At step  220 , a first light sensor  110  and a second light sensor  150  are provided. 
     At step  230 , a video sequence to be sequentially projected by the projector is evaluated responsive to an output of the first sensor  110  to determine a frequency F and time instant at which frames in the video sequence are projected during the sequential projecting thereof. The time instant can be the time instant corresponding to the displaying of the first frame of the video sequence, or can correspond to any other frame. It is to be appreciated that simply determining a single time instant at which a single frame is projected along with the frequency F allows for the readily determination of the corresponding time instants for other frames in the video sequence, presuming a fixed temporal distance between consecutive frames. 
     At step  240 , the video sequence is evaluated responsive to an output of the second sensor  150  to determine the time instant at which the edge  141  between the at least two polarized zones on the circular polarized filter  140  crosses a particular point. The point can correspond to, for example, a location in between at least two frames or a location in between one frame, e.g., in between the top and bottom fields. Of course, other locations can also be used. 
     The former evaluation (as per step  230 ) can be considered to be a temporal evaluation in that timing information is determined there from, while the second evaluation (as per step  240 ) can be considered a spatial evaluation in that one or more correlations in space are determined. In any event, the results of both evaluations are used (at step  250 ) to rotate the circular filter  140  at the proper speed and so as to place the appropriate one of the two polarized zones at the proper location in front of the projection lens  101 . 
     At step  250 , the circular polarized filter  140  having the at least two polarized zones is automatically rotated on the shaft  131  of the DC motor  130  responsive to the information determined from the temporal control output signal and the spatial control output signal such that the shaft is rotated at a speed equal and/or otherwise corresponding to the frequency F, with one of the two polarized zones being respectively positioned in front of the projector lens  101  at any given time during the rotation of the circular filter. 
     Regarding another exemplary embodiment, an apparatus and/or method is configured to swap views. That is, using input from the user, the motor can spin faster or slower for a few instants in order to use an appropriate filter for a given view. The user input is used because the system does not know if it is using the proper filter for the frames that are being displayed through the projector. 
     Turning to  FIG. 3 , another exemplary apparatus for upgrading a projector to display three-dimensional content is indicated generally by the reference numeral  300 . The apparatus  300  includes a Direct Current (DC) motor  330 , a circular polarized filter  340 , and a user input device  360 . The circular polarized filter  340  is manufactured and/or otherwise provided to have at least two polarized zones thereon, namely at least a first polarized zone  345  and a second polarized zone  346 , with at least one edge  341  separating the at least two first and second zones  345  and  346 . 
     The user input device  360  is connected in signal communication with the DC motor  330 , and is used to control a speed at which the circular polarized filter is rotated around the shaft  331  of the DC motor  330 . In this way, the DC motor  130  spins so that the attached circular polarized filter  340  is (manually) adjusted to spin at the proper speed which respectively places an appropriate one of the at least two polarized zones of the circular polarized filter  340  in front of an applicable frame of the video sequence to obtain a desired polarization thereof. For example, such speed can be equal to and/or other correspond to a frequency F and a time at which frames of a particular video sequence are projected during a sequential showing of the particular video sequence, as ascertained by, e.g., the user providing the user input. 
     It is to be appreciated that the user input device  360  can be a device that receives a user input and provide a respective output current and/or voltage responsive to the user input. Thus, for example, such user input device  360  can include a keyboard, buttons, a foot pedal, and/or so forth, where depending upon which key or button is depressed and/or an amount of displacement of, e.g., a key, button and/or the foot pedal, the output current and/or voltage provided to the motor  130  is adjusted accordingly. In other embodiments, a processor (not shown in  FIG. 3 , but shown in  FIG. 1 ) can be used, where the user input (e.g., which key is pressed, how much are one or more keys depressed, and so forth) is judged by the processor in order to adjust (step up or step down) the current and/or voltage provided to the motor  350 . 
     Turning to  FIG. 4 , another exemplary method for upgrading a projector to display three-dimensional content is indicated generally by the reference numeral  400 . At step  410 , a user input device  360  is provided along with a motor  330  having a shaft  331  on which is mounted a circular polarized filter  340  having at least two polarized zones. At step  420 , a user input is received that causes the shaft  331  of the motor  330  to rotate and, hence, the circular polarized filter  340  attached thereto. At step  430 , the rotation of the circular polarized filter  340  is controlled responsive to the user input such that one of the at least two polarized zones is positioned in front of the projector lens at any given time. 
     It is to be appreciated that while a Direct Current motor is described with respect to one or more embodiments of the present principles, the embodiments are not limited to DC motors and, thus, other types of motors can also be used in accordance with the teachings of the present principles, while maintaining the essence of the present principles. 
     It is to be further appreciated that one of the many advantages of the present principles is that manipulation of the projector is not required to upgrade the functionality of the projector. Moreover, it is to be appreciated that the zone between the two polarized filters can be opaque to avoid light from the projector coming through when the filter is alternating. 
     These and other features and advantages of the present principles can be readily ascertained by one of ordinary skill in the pertinent art based on the teachings herein. It is to be understood that the teachings of the present principles can be implemented in various forms of hardware, software, firmware, special purpose processors, or combinations thereof. 
     Most preferably, the teachings of the present principles are implemented as a combination of hardware and software. Moreover, the software can be implemented as an application program tangibly embodied on a program storage unit. The application program can be uploaded to, and executed by, a machine comprising any suitable architecture. Preferably, the machine is implemented on a computer platform having hardware such as one or more central processing units (“CPU”), a random access memory (“RAM”), and input/output (“I/O”) interfaces. The computer platform can also include an operating system and microinstruction code. The various processes and functions described herein can be either part of the microinstruction code or part of the application program, or any combination thereof, which can be executed by a CPU. In addition, various other peripheral units can be connected to the computer platform such as an additional data storage unit and a printing unit. 
     It is to be further understood that, because some of the constituent system components and methods depicted in the accompanying drawings are preferably implemented in software, the actual connections between the system components or the process function blocks can differ depending upon the manner in which the present principles are programmed. Given the teachings herein, one of ordinary skill in the pertinent art will be able to contemplate these and similar implementations or configurations of the present principles. 
     Although the illustrative embodiments have been described herein with reference to the accompanying drawings, it is to be understood that the present principles is not limited to those precise embodiments, and that various changes and modifications can be effected therein by one of ordinary skill in the pertinent art without departing from the scope of the present principles. All such changes and modifications are intended to be included within the scope of the present principles as set forth in the appended claims.