You are an expert at summarizing long articles. Proceed to summarize the following text:

You are an expert at summarizing long articles. Proceed to summarize the following text: 
BACKGROUND OF THE INVENTION 
       [0001]    1. Technical Field 
         [0002]    The present disclosure relates generally to roller shades, and more particularly to a motorized roller shade with a sun angle sensor. 
         [0003]    2. Background Art 
         [0004]    Typical motorized roller shades provide privacy, glare control, minimize heat gain, and prevent damage to interior furnishings by minimizing the effects of ultra violet radiation from the sun. In order to realize these benefits, roller shades are manually adjusted by the occupant to solve one or more of the above-mentioned issues. 
       SUMMARY OF THE INVENTION 
       [0005]    It is to be understood that both the general and detailed descriptions that follow are exemplary and explanatory only and are not restrictive of the invention 
       DISCLOSURE OF THE INVENTION 
       [0006]    According to one aspect, the invention involves a motorized roller shade system. The system includes a flexible shade material, a roller tube configured for windingly receiving the flexible shade material, a shade motor coupled to the roller tube, a motor controller in communication with the shade motor, and a sun angle sensor. The sun angle sensor is configured for determining the angle of the sun and transmitting the angle of the sun to the motor controller. The motor controller is configured for driving the shade motor to rotate the roller tube to wind or unwind the flexible shade material in response to the transmitted angle of the sun to limit sunlight penetration through a window to a predetermined maximum distance into a room. 
         [0007]    In one embodiment, the roller shade system further includes a memory configured for storing a height of the window covered by the flexible shade material and a height of a window sill associated with the window. 
         [0008]    In another embodiment, the motor controller is further configured for driving the shade motor to rotate the roller tube to wind or unwind the flexible shade material in response to the stored height of the window and the stored height of the window sill associated with the window to limit sunlight penetration through the window to a predetermined maximum distance into the room. 
         [0009]    In still another embodiment, the motor controller includes a microcontroller, a controller interface, a memory, and a motor driver circuit in communication with the motor. 
         [0010]    In various embodiments, the sun angle sensor is solar powered, and the sun angle sensor transmits the angle of the sun to the motor controller through one of a wired connection and a wireless connection. 
         [0011]    According to another aspect, the invention involves a method of limiting the maximum distance sunlight penetrates through a window into a room. The method includes providing for the window a roller shade that includes a flexible shade material, a motor, a motor controller, and a sun angle sensor. The method further includes storing a height of the window and a height of a window sill associated with the window. The method further includes determining, by the sun angle sensor, the angle of the sun, transmitting the angle of the sun to the motor controller, and driving the shade motor, by the motor controller, to wind or unwind the flexible shade material in response to the transmitted angle of the sun, the stored height of the window, and the stored height of a window sill to limit sunlight penetration through the window to a predetermined maximum distance into the room. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The accompanying figures further illustrate the present invention. Exemplary embodiments are illustrated in reference figures of the drawings. It is intended that the embodiments and figures disclosed herein are to be considered to be illustrative rather than limiting. 
           [0013]    The components in the drawings are not necessarily drawn to scale, emphasis instead being placed upon clearly illustrating the principles of the present invention. In the drawings, like reference numerals designate corresponding parts throughout the several views. 
           [0014]      FIG. 1  is an illustrative diagram of a motorized roller shade employing a sun angle sensor, according to one embodiment of the invention. 
           [0015]      FIG. 2  is an illustrative block diagram of a motorized roller shade, motor controller, and sensor, according to one embodiment of the invention. 
           [0016]      FIG. 3  is an illustrative diagram of a motorized roller shade position based on sun angle for a floor to ceiling window, according to one embodiment of the invention. 
           [0017]      FIG. 4  is an illustrative diagram of a motorized roller shade position based on sun angle for a standard window, according to one embodiment of the invention. 
       
    
    
       [0018]    LIST OF REFERENCE NUMBERS FOR THE MAJOR ELEMENTS IN THE DRAWINGS 
         [0019]    The following is a list of the major elements in the drawings in numerical order.
     102  roller shade     104  roller tube     106  flexible shade material     108  hembar     110  shade motor     112   a  sensor     112   b  sensor     114  window     116  window frame     118  window sill     202  motor controller     204  memory     206  controller interface     208  microcontroller/microprocessor     210  motor driver circuit     212  master controller     214  photovoltaic cell     216  microcontroller/microprocessor     218  communication interface     302  window     304  shade     306  sun rays     402  window     404  shade     406  sun rays   
 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0045]    Reference will now be made to the exemplary embodiments illustrated in the drawings, and specific language will be used herein to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended. Alterations and further modifications of the inventive features illustrated herein, and additional applications of the principles of the inventions as illustrated herein, which would occur to one skilled in the relevant art and having possession of this disclosure, are to be considered within the scope of the invention. 
         [0046]    Unless the context clearly requires otherwise, throughout the description and the claims, the words ‘comprise’, ‘comprising’, and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”. 
       Mode(s) for Carrying Out the Invention 
       [0047]    Disclosed is a motorized roller shade system that automatically adjusts the position of the shade to minimize UV penetration into a room and prevent glare on items, such as television screens, by specifying the maximum distance into a room from a window that direct sunlight may penetrate. 
         [0048]    Referring to  FIG. 1 , in one embodiment, the shade system, which is designed to be mounted in a window frame  116  and cover window  114 , includes a roller shade  102 , a roller shade motor  110 , and a sun angle sensor (generally  112 ). The roller shade  102  includes a roller tube  104 , flexible shade material  106 , and a hembar  108 . The motor  110  is in wired communication with, and controlled by, a motor controller  202  ( FIG. 2 ). The sensor  112  is in wired or wireless communication with the motor controller  202 . In one embodiment, the sensor  112  is an integrated solar angle sensor E910.86 from Elmos, Inc. The sensor  112  is capable of determining the angle of light incidence in both xz- and yz-planes, with the z axis being perpendicular to the surface of the sensor  112 , the x axis being parallel to the surface sensor and parallel to the surface of a window sill  118 , and the y axis being parallel to the surface sensor and perpendicular to the surface of the window sill  118 . In one embodiment, the sensor  112   a  is disposed on a surface of the window  114 . In another embodiment, the sensor  112   b  is disposed on the window sill  118 . 
         [0049]    The motor controller  202  controls/drives the motor  110  and includes a microcontroller/microprocessor  208 , a controller interface  206 , a memory  204 , and a motor driver circuit  210 , which is in communication with the motor  110 . The controller interface  206  is in wired or wireless communication with a master controller  212 , which is capable of controlling one or more motor controllers  208 . During installation of the roller shade system, the height (h) of the top of the window above the floor and the height (s) of the window sill are stored in the memory  204 . In the case of a window that extends to the floor (i.e., no window sill), height s=0. 
         [0050]    In various embodiments, the sensor  112 , which is in wired or wireless communication with the microcontroller  208 , includes at least one photovoltaic cell  214 , a microcontroller/microprocessor  216 , and a wired or wireless communication interface  218 . The sensor  112  is removeably coupled to the window  114  or disposed on a window sill  118  in order to have an unobstructed view of the sun. If the sensor  112  is in wired communication with the microcontroller  208 , the sensor  112  receives power through/from the motorized roller shade. If the sensor  112  is in wireless communication with the microcontroller  208 , the sensor  112  is battery powered and/or solar powered. 
         [0051]    The sensor  112  determines the angle of the sun based on sunlight incident thereon, and reports/transmits the sun angle to the microcontroller  208 . The microcontroller  208  also retrieves height (h) and height (s) from memory  204 . In response to receiving the sun angle and retrieving height (h) and height (s), the microcontroller  208  instructs the motor  110  (via the motor driver circuit  210 ) to move the roller shade  102  up or down to allow sunlight to enter a predetermined (user defined) distance (a) into a room. Because the sensor  112  detects actual light conditions, there is no need to specify the location (i.e., latitude and longitude) of the building or whether there are any obstructions between the window and the sun. Furthermore, the sensor  112  also determines the intensity of the sun and thus eliminates the need for additional sensors to detect clouds and/or shadows. 
         [0052]    The disclosed roller shade system prevents furnishings, artwork, or other materials from being damaged by the sun&#39;s harmful ultraviolet (UV) rays. For example, if a user knows that all the items in a particular room that could be damaged by Ultraviolet rays are a minimum of five feet away from the windows, the disclosed roller shade system can be easily configured to allow direct sunlight to penetrate no more than five feet into the room. 
         [0053]    Referring to  FIG. 3 , in one embodiment, in operation with a floor to ceiling window  302 , assume a user wants to position a shade  304  so that sunlight penetrates into a room a maximum distance (a) of five feet. Next assume that the distance (h) from the top of a window  302  employing the disclosed roller shade system to the floor is ten feet (i.e., shade length). Further assume that the sensor  112  determines that the angle (theta) of incidence of the sun rays  306  is 50 degrees, in the yz-plane relative to the z-axis. The distance b is the distance from the floor that the shade  304  needs to be raised to allow sunlight to penetrate into the room a maximum of five feet 
         [0054]    The distance b is determined using the equation: Tan (theta)=b/a. For the current example, b=Tan (50)*5=5.958≈6 feet, or 60 percent of the total shade length (i.e., 10 feet). In other words, the shade  304  must be 60 percent open to allow the incident light rays  306  to penetrate a distance of 5 feet into the room. 
         [0055]    Referring to  FIG. 4 , in another embodiment, in operation with a standard sized window  402 , assume a user wants to position a shade  404  so that sunlight penetrates into a room a maximum distance (a) of five feet. Next assume that the distance (h) from the top of a window  402  employing the disclosed roller shade system to the floor is ten feet and that the height (s) of the window sill is two feet. Further assume that the sensor  112  determines that the angle (theta) of incidence of the sun rays  406  is 50 degrees, in the yz-plane relative to the z-axis. In this example, the relative position (RP) that the shade  404  needs to be raised to allow sunlight to penetrate into the room a maximum of five feet is determined by the equation RP=(b/(h−s))*100. 
         [0056]    The distance b is determined using the equation: Tan (theta)=b/a. For the current example, b=Tan (50)*5=5.958≈6 feet. Using the above described equation, RP=(6/(10−2))*100=75% open. In other words, the shade  404  must be 75 percent open to allow the incident light rays  406  to penetrate a distance of 5 feet into the room. 
         [0057]    As mentioned above, the sensor  112  is capable of determining the angle of light incidence in both xz- and yz-planes, with the z axis being perpendicular to the surface of the sensor  112 , the x axis being parallel to the surface sensor and parallel to the surface of the window sill  118 , and the y axis being parallel to the surface sensor and perpendicular to the surface of the window sill  118 . Consequently, the sensor can be used with drapery tracks, vertical blinds, venetian blinds, or any other type of motorized window treatment. In the case of the sensor  112  being used with drapes or vertical blinds, a user can set a maximum horizontal width that direct sunlight covers, rather than the maximum distance that direct sunlight may penetrate. 
         [0058]    In another embodiment, the sensor additionally includes a memory configured for storing the height (h), the height (s), and the maximum distance sunlight is allowed to penetrate into the room. After the sensor determines the angle of the sun, the microcontroller/microprocessor performs the calculations described above to determine the percentage open (e.g., 0=closed, 100=fully open, 50=50% open) the shade needs to be to limit the sunlight penetration into the room to the predetermined maximum distance. The sensor then transmits the percentage open to the shade motor, which moves the flexible shade material to the appropriate position. 
       ALTERNATIVE EMBODIMENTS 
       [0059]    Variations, modifications, and other implementations of what is described herein may occur to those of ordinary skill in the art without departing from the spirit and scope of the invention. Accordingly, the invention is not to be defined exclusively by the preceding illustrative description.

Summary:
Presented is a motorized roller shade system. The system includes a flexible shade material, a roller tube configured for windingly receiving the flexible shade material, a shade motor coupled to the roller tube, a motor controller in communication with the shade motor, and a sun angle sensor. The sun angle sensor is configured for determining the angle of the sun and transmitting the angle of the sun to the motor controller. The motor controller is configured for driving the shade motor to rotate the roller tube to wind or unwind the flexible shade material in response to the transmitted angle of the sun to limit sunlight penetration to a predetermined maximum distance into a room.