Abstract:
An image projection system is disclosed. The system comprises a projector, a user input device and a computing device. The micro-mirror based projector projects an image including a cursor on a display plane. The present invention discloses various embodiments for the system and method of adjusting the brightness of the cursor to improve effects of a presentation. According to one embodiment, the brightness of the cursor is adjusted by modifying the on/off time ratio of the mirrors by which the cursor is formed. According to another embodiment, the projector comprises a first and a second micro-mirror array. The second array is dedicated for projecting the cursor image. The brightness of the cursor may be adjusted by changing the number of micro-mirrors by which the cursor is formed from the second array.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    Not applicable. 
       BACKGROUND 
       [0002]    1. Field of Invention 
         [0003]    This invention relates to an image projection system, specifically to an image projection system with adjustable cursor brightness. 
         [0004]    2. Description of Prior Art 
         [0005]    When making a presentation for a lecture or the like using a micro-mirror based projector, a laser pointer, which indicates a point on a screen by projecting a laser beam is often used. A laser pointer of this type has, however, the following disadvantages. Shake greatly and adversely influences the pointing operation, thereby making the point unstable. A laser beam may be erroneously projected to be hazardously incident on eyes of audience. In addition, the shape of point is limited to simple shapes such as a circle and a line, which can not satisfy the demand for changing the shape of the point according to the user&#39;s preference. Furthermore, the brightness of the point cannot be adjusted. 
         [0006]    Conventional computer pointing devices such as a mouse, a trackball, or a touchpad are also known in the prior art. The pointing devices allow a user to control the operation of a cursor on a computer screen and therefore a cursor on a large display plane in a synchronized manner for a presentation system comprising a projector and a computer. Most pointing devices are connected to a computer through a wire. This limits the use of such devices as a control and presentation tool because the wire limits their range of movement and flexibility of connections. 
         [0007]    Wireless pointing devices have become available in recent years. The devices allow for greater range of movement and connection flexibility. The wireless pointing devices are preferred for the projector because the lack of a wire or a cord allows a user to freely move about while continuing to maintain control of a cursor on the display plane. 
         [0008]    However, a problem with the computer based presentation system with a cursor as the point is that the cursor has the same brightness as the projected image. Audiences may encounter difficulties in capturing the cursor&#39;s position on the display plane. 
         [0009]    It is therefore desirable to have a computer based presentation system with adjustable cursor brightness, in particularly, with brighter cursor to enable the audiences to capture the movement and position of the cursor easily. 
       SUMMARY OF THE INVENTION 
       [0010]    It is therefore an object of the present invention to provide an image projection system with adjustable cursor characteristics, in particularly the cursor brightness to improve experience of the presenter and the audience. 
         [0011]    In one embodiment of the present invention, the brightness of the cursor is adjusted by modifying the on/off time ratio of selected micro-mirrors by which the light beams reflected form pixels of the cursor image. 
         [0012]    In another embodiment of the present invention, the image projector comprises a first micro-mirror array for projecting an image such as a slide for a presentation and a second micro-mirror array for projecting an image of a cursor. The projected image of the cursor is formed by a plurality of pixels. The brightness of the cursor may be adjusted by selecting an appropriate number of micro-mirrors from the second array. More mirrors are selected, brighter the cursor. The second array should have a sufficiently large number of mirrors to allow the user to adjust the brightness in a desired range. The micro-mirror arrays are controlled by a controller. The controller translates the user&#39;s instructions from the input device into a series of controlling signals for the controller to control the operation of the arrays. The first and the second micro-mirror arrays may be integrated into a single chip. 
         [0013]    In yet another embodiment, the methods of modifying the on/off time ratio of the mirrors and the one of using the second micro-mirror array may be combined to deliver a cursor with adjustable brightness. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    For a more complete understanding of the present invention and its various embodiments, and the advantages thereof, reference is now made to the following description taken in conjunction with the accompanying drawings. 
           [0015]      FIG. 1A  is a schematic diagram of an exemplary projector according to one embodiment of the present invention. The brightness of the cursor is adjusted by modifying the on/off time ratio of the micro-mirrors by which the reflected light beams form the image of the cursor. 
           [0016]      FIG. 1B  is a schematic diagram of an exemplary projector according to another embodiment of the present invention. The brightness of the cursor is adjusted by selecting an appropriated number of micro-mirrors from the second micro-mirror array to form the image of the cursor. 
           [0017]      FIG. 2  is a schematic illustration that the first and the second micro-mirror arrays are integrated in a single chip in an exemplary case. 
           [0018]      FIG. 3A  is a schematic functional block diagram of an image projection system in one embodiment that the user input device is connected to the computing device. 
           [0019]      FIG. 3B  is a schematic functional block diagram of an image projection system in another embodiment that the user input device is connected to the projector directly. 
           [0020]      FIG. 4  is a flow diagram depicting steps of operations of the image projection system in accordance with one embodiment of the present invention that the brightness of the cursor is adjusted by modifying the on/off time ratio of the micro-mirrors by which the reflected light beams form the cursor. 
           [0021]      FIG. 5  is a schematic diagram of the user selectable interface for the characteristics of the cursor. 
           [0022]      FIG. 6  is a flow diagram depicting steps of operations of the image projection system in accordance with another embodiment of the present invention that the brightness of the cursor is adjusted by selecting an appropriate number of micro-mirrors from the second array. 
           [0023]      FIG. 7  is a flow diagram depicting steps of operations of the image projection system in accordance with yet another embodiment of the present invention that the brightness of the cursor is adjusted by modifying on/off time ratio of the selected number of micro-mirrors from the second array. 
           [0024]      FIG. 8  is a flow diagram depicting steps of operations of the image projection system in accordance with yet another embodiment of the present invention that the user input device is connected through the computing device. 
       
    
    
     DETAILED DESCRIPTION 
       [0025]    The present invention will now be described in detail with references to a few preferred embodiments thereof as illustrated in the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art, that the present invention may be practiced without some or all of these specific details. In other instances, well known process steps have not been described in detail in order not to unnecessarily obscure the present invention. 
         [0026]    The present invention is based upon a micro-mirror array device or Digital Light Processing (DLP). DLP is a trademark owned by Texas Instruments, Dallas, Tex., representing a technology used in projectors and video projectors. It was originally developed by Larry Hornbeck of Texas Instruments. In DLP projectors, the image is created by microscopically small mirrors laid out in a matrix on a semiconductor chip, known as a Digital Micro-mirror Device (DMD). Each mirror represents one or more pixels in the projected image. 800×600, 1024×768, 1280×720, and 1920×1090 (HDTV) matrices are common DMD sizes. These mirrors can be repositioned rapidly to reflect light either through the lens or on to a heat-sink. 
         [0027]    Rapidly toggling the mirror between these two orientations (essentially on and off) produces grayscales, controlled by the on/off time ratio. 
         [0028]    One of the methods by which DLP projection systems create a color image is by a single DLP chip approach. Colors are either produced by placing a color wheel between the lamp and the DLP chip or by using individual light sources to produce primary colors, LED&#39;s for example. The color wheel is divided into multiple sectors: the primary colors: red, green and blue, and in many cases secondary colors. 
         [0029]    The DLP chip is synchronized with the rotating motion of the color wheel so that the red component is displayed on the DMD when the red section of the color wheel is in front of the lamp. The same is true for the green, blue and other sections. The colors are thus displayed sequentially at a sufficient high rate that the observer sees a composite “full color” image. 
         [0030]    The main light source used on micro-mirror or DLP-based projector is based on a replaceable high-pressure mercury-vapor metal halide arc lamp unit (containing a quartz arc tube, reflector, electrical connections, and sometimes a quartz/glass shield), while in some newer DLP projectors high power LED&#39;s are used as a source of illumination. 
         [0031]    The brightness of a projected image can be adjusted by modifying the on/off time ratio of the mirrors. According to one embodiment of the present invention, the brightness of a cursor image may be adjusted by modifying the on/off time ratio of the micro-mirrors by which the cursor image is formed through the reflection of the light beams. 
         [0032]    The brightness of a projected image can also be adjusted by directing more or less light beams reflected from the micro-mirrors to form the image of the cursor. A second micro-mirror array may be utilized in a dedicated manner to project the image of the cursor. The number of mirrors in the second array needs to be sufficiently high to allow the brightness of the cursor be adjusted in a desired range. 
         [0033]    The brightness of a projected image can further be adjusted by combining the modification of the on/off time and the selection of an appropriate number of mirrors from a dedicated array. 
         [0034]      FIG. 1A  is a schematic diagram of an exemplary projector  100  according to one embodiment of the present invention. The projector  100  comprises a light source  102 , a micro-mirror array  104 , and a controller  106 . The light source  102  may be a replaceable high-pressure mercury-vapor metal halide arc lamp unit with a color wheel. The light source  102  may also be a plurality of high power LED&#39;s. The micro-mirror array  104  may be a DMD or DLP. The controller  106  may be a data processor pertaining to control the operations of the micro-mirror array and the projector. The projector  100  further comprises an optical unit such as lens for directing light beams reflected by the micro-mirror array  104  from the light source  102  to a display plane. The communication unit  110  is for connecting the projector  100  with a computing device and/or a user input device. The communication unit  110  may be a wired connection such as for example an IEEE 1394 type of connection (FIREWIRE) or a Universal Serial Bus type of connection (USB). The communication unit  110  may also be a wireless communication transceiver such as a Bluetooth, WiFi, and ZigBee type of transceiver. A power supply  112  supplies power for the operations of the projector. The projector  100  further comprises a cursor control unit  114 .  114  may be implemented as a piece of software.  114  may also be implemented as a piece of hardware or a combination of software and hardware.  114  may be a part of the controller  106 . 
         [0035]    After receiving the user&#39;s selections of the characteristics (e.g. shape, size, color, and brightness) of the cursor from a user interface at a setup phase of the projector, the cursor control unit  114  translates the selections into a set of parameters for controlling the operations of the micro-mirrors by which the cursor is formed. When a user operates a user input device to move the cursor to a desired position on the display plane, a coordinate of the cursor is determined by the controller  106 . Micro-mirrors forming the cursor image corresponding to the coordinate are determined. The predetermined control parameters such as the on/off time ratio are applied to each mirror forming the cursor to project a desired image. When the cursor is moving on the display plane, the above mentioned operation is repeated in a rapid manner. The user and the audiences will only observe a moving cursor with desired characteristics. 
         [0036]      FIG. 1B  is a schematic diagram of an exemplary projector  101  according to another embodiment of the present invention. The projector  101  comprises a conventional DLP based projector  103  and various units as illustrated in an add-on module  105 . The embodiment is characterized by that the projector  101  includes a first micro-mirror array  104  and a second micro-mirror array  114 . The second micro-mirror array  114  is dedicated to generate the cursor image. The brightness of the cursor image can be increased significantly by directing more light beams reflected by more micro-mirrors than normally required to form the cursor image. The operation of  114  is controlled by the second controller  116 . The first and the second micro-mirror array  104 / 114  may be integrated in a single chip. The cost by adding a fraction of more micro-mirrors in the same chip is low based upon the integrated circuits based micro-machining process. The first and second controllers  106 / 116  may be in an integrated form. They may also be separate units. 
         [0037]    The second communication unit  118  is used to connect the projector with a user input device.  118  may be a part of wired connection such as the FIREWIRE or the USB type of connection. A wired connection, however, limits the movement of the user (presenter) within a range defined by the length of the connecting cable. A wireless connection by, for example, the Bluetooth transceiver may provide more flexibility for the user. 
         [0038]      FIG. 2  is a schematic diagram that the first and the second micro-mirror arrays are integrated in a single chip in an exemplary case. The micro-mirrors from the second array may be grouped together as illustrated in the figure. It is, however, not necessary to arrange the mirrors in such a manner. The mirrors from the second array may be arranged in other manners as appropriated. For example, the mirrors from the second array may be divided into four subgroups and be placed at four different corners of the first array. 
         [0039]      FIG. 3A  is a schematic functional block diagram of an image projection system according to one embodiment. The projection system  300  comprises a projector  302 , a display  304 , a computing device  306  and a user input device  308 . The computing device  306  may be a general purpose computer. The computing device  306  comprises a display screen  310 . The user input device  308  may be a mouse of the computer. The mouse may be connected to the computer in a wired manner or in a wireless manner as known in the art. After the computing device  306  is connected to the projector  302 , the movement of the cursor on the display  304  and the movement of the cursor on the display screen  310  of the computing device  306  are synchronized. The user can control the movement of the cursor on the display  304  by the use of the input device  308 . 
         [0040]      FIG. 3B  is a schematic functional block diagram of an image projection system in another embodiment. The image projection system  301  comprises the projector  302 , the display  304 , the computing device  306  and the user input device  308 . The user input device  308  is connected to the projector  302  directly according to the embodiment. The projector  302  may include a wireless communication unit.  308  may be a wireless mouse in an exemplary embodiment. The advantage of the present embodiment is that the user input device  308  is always connected to the projector even when the computing device  306  is replaced by a different one owned by a different presenter. When the computing device  306  is connected to the projector  302 , the movement of the cursor on the display screen  310  of the computing device  306  and the movement of the cursor on the display  304  are synchronized. 
         [0041]      FIG. 4  is a flow diagram depicting steps of operations of the image projection system  301 . Process  400  starts with step  402  that the projector  302  is switched on by the user. The user input device  308  is connected to the projector  302  in step  404 . A preliminary (or default) cursor image accompanying with a user selectable interface is then displayed on the display  304  in step  406 . An exemplary user interface is illustrated in  FIG. 5 . The characteristics of the cursor include its shape, size, color and brightness. C 1  to C 4  in the figure stands for different colors. The user can select the desired characteristics by moving the cursor to the right position and actuating the input device  308  to make the selection. The user&#39;s selections are received by the projector  302  in step  408 . The micro-mirrors by which the cursor is formed is determined in step  410  based upon the shape and size of the cursor selected by the user. The color and the brightness of the cursor is determined by the on/off time ratio for each micro-mirror and for each primary and each secondary color if it is used. An updated cursor is displayed in step  412 . It should be noted that steps from  408  to  412  may be repeated until a desired cursor image is established. After the computing device  306  is connected to the projector  302  in step  414 , an image such as a slide is delivered by the computing device  306  to the projector  302  and, consequently on the display  304  in step  416 . The user can then move the cursor with desired characteristics on the display as a point. 
         [0042]      FIG. 6  is a flow diagram depicting steps of operations of the image projection system  301  according to the embodiment that the projector  302  comprising the first and the second micro-mirror arrays  104 / 114 . The second micro-array  114  is dedicated to project the cursor image. Process  600  starts with step  602  that the projector  302  is switched on by the user. The user input device  308  is connected to the projector  302  in step  604 . A preliminary (or default) cursor image accompanying with a user selectable interface is then displayed on the display  304  in step  606 . The user&#39;s selections are received by the projector  302  in step  608 . The number of micro-mirrors by which the cursor is formed is determined in step  610  based upon shape, size and brightness of the cursor selected by the user. The color of the cursor is determined by controlling the on/off time ratio for each primary and each secondary color if it is used. The brightness of the cursor is changeable depending on the number of micro-mirror selected from the second array  114 . More micro-mirrors from the second array are selected, brighter the cursor. An updated cursor is displayed in step  612 . Steps from  608  to  612  may be repeated by the user until a satisfactory cursor image is displayed. After the computing device  306  is connected to the projector  302  in step  614 , an image such as a slide is delivered by the computing device  306  to the projector  302  and, consequently on the display  304  in step  616 . 
         [0043]      FIG. 7  is a flow diagram depicting steps of operations of the image projection system  301  according to the embodiment that the projector  302  comprising the first and the second micro-mirror arrays  104 / 114 . Further, the brightness of the cursor image may be adjusted by selecting the number of micro-mirror by which the cursor is formed and also by modifying the on/off time ratio for each selected mirror. The second micro-mirror array  114  is dedicated to project the cursor image. Process  700  starts with step  702  that the projector  302  is switched on by the user. The user input device  308  is connected to the projector  302  in step  704 . A preliminary (or default) cursor accompanying with a user selectable interface is then displayed on the display  304  in step  706 . The user&#39;s selections are received by the projector  302  in step  708 . The number of micro-mirrors from the second array  114  is determined in step  710  based upon the user selected shape, size and brightness of the cursor. The color of the cursor is determined by controlling the on/off time ratio for each primary and each secondary color if it is used. The brightness of the cursor is changeable depending on the number of micro-mirror selected from the second array  114 . The brightness of the cursor can be further modified by controlling the on/off time ratio of each selected micro-mirror from the second array. An updated cursor is displayed in step  712 . Steps from  708  to  712  may be repeated until a satisfactory cursor image is displayed. After the computing device  306  is connected to the projector  302  in step  714 , an image such as a slide is delivered by the computing device  306  to the projector  302  and, consequently on the display  304  in step  716 . 
         [0044]      FIG. 8  is a flow diagram depicting steps of operations of the image projection system  300  (the user input device  308  is connected to the computing device  306 ). Process  800  starts with step  802  that the projector  302  is switched on by the user. The computing device  306  is connected to the projector  302  in step  804 . The movement of the cursor on the display screen  310  of the computing device  306  is synchronized in step  806  with the movement of the cursor on the display  304 . A preliminary (or default) cursor accompanying with a user selectable interface is then displayed on the display  304  in step  808 . The user&#39;s selections are received by the projector  302  in step  810 . The number of micro-mirrors from the second array  114  by which the cursor is formed is determined in step  812  based upon shape, size and brightness of the cursor selected by the user. The color of the cursor is determined by controlling the on/off time ratio for each primary color and each secondary color if it is used. The brightness of the cursor is changeable depending on the number of micro-mirror selected from the second array  114 . The brightness of the cursor can be further modified by controlling the on/off time ratio of each selected micro-mirror. An updated cursor is displayed in step  814 . Steps  810  to  814  may be repeated until a satisfactory cursor image is displayed. An image such as a slide is delivered by the computing device  306  to the projector  302  and, consequently on the display  304  in step  816 . 
         [0045]    While the invention has been disclosed with respect to a limited number of embodiments, numerous modifications and variations will be appreciated by those skilled in the art. It is intended that all such variations and modifications fall within the scope of the following claims: