Abstract:
Three dimensional (3D) glasses, a 3D display apparatus, and a 3D glasses charging system are provided. The 3D glasses, which operate in association with a 3D display apparatus, includes an interface unit which is configured to connect to the 3D display apparatus, and through which power is transmittable; a battery unit which supplies power to the 3D glasses; and a charging unit which is connected to the interface unit and the battery unit, and receives power input from the interface unit and charges the battery unit using the input power.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority from Korean Patent Application No. 10-2010-034309, filed on Apr. 14, 2010, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety. 
       BACKGROUND 
       [0002]    1. Field 
         [0003]    Glasses, apparatuses, and systems consistent with exemplary embodiments relate to three-dimensional (3D) glasses implementing a manner of displaying left-eye images and right-eye images alternately, a 3D display apparatus and a system for charging the 3D glasses. 
         [0004]    2. Description of the Related Art 
         [0005]    3D image technology has been applied in various fields such as communications, broadcasting, medical services, education, military, computer games, computer animation, virtual reality, computer-aided design (CAD), industrial technology, and the like. For all of the above areas, 3D image technology is a key enabling technology of the next generation 3D multimedia telecommunication. 
         [0006]    A person perceives a stereoscopic sense due to related effects, including changes in the thickness of a person&#39;s lens depending on a position of an object being viewed, the difference in the angle of the object as perceived by the left eye and the right eye, changes in position and form of the object as perceived by the left eye and the right eye, disparity caused by object movement, and various other psychological and memory effects. 
         [0007]    The binocular disparity, caused by an approximate 6 to 7 centimeter lateral distance between a person&#39;s left and right eyes, is one of the most influential causes of the stereoscopic sense. Due to binocular disparity, a person perceives an object at different angles, causing the left and right eyes to receive different images from each other and thus enabling the person&#39;s brain to perceive an object with depth by fusing the two different pieces of image information precisely as these are received through the retina. 
         [0008]    3D image display apparatuses are generally classified as eyeglasses types or a non-eyeglasses types. An eyeglasses type apparatus may be a color filter apparatus which filters an image using a color having complementary color filters; a polarizing filter type apparatus which divides an image into left- and right-eye images using a shading effect caused by combining orthogonal polarized light elements; and a shutter glasses type apparatus which alternately blocks a left eye and a right eye in response to a synchronization signal that projects a left-eye image signal and a right-eye image signal onto a screen. 
         [0009]    However, it is necessary for a viewer to wear 3D glasses to watch view an image from an eyeglasses type apparatus. 
         [0010]    A disposable battery may be inserted in the 3D glasses to power the 3D glasses, or the 3D glasses may be charged using a separate charger. In the case of a disposable battery, user convenience declines due to the need for frequent battery replacement and battery costs. Using a separate charger also may not be an ideal option, particularly considering the fact that a user has to purchase a separate charger to charge the 3D glasses. 
         [0011]    Therefore, an improvement is desired, which enables a user to charge the 3D glasses more conveniently. 
       SUMMARY OF THE INVENTION 
       [0012]    Exemplary embodiments overcome the above disadvantages and other disadvantages not described above. Also, the embodiments are not required to overcome the disadvantages described above, and an exemplary embodiment of the present inventive concept may not overcome any of the problems described above. 
         [0013]    According to an aspect of an exemplary embodiment, there is provided 3D glasses operating in association with a 3D display apparatus, the 3D glasses including an interface unit, adapted to connect to the 3D display apparatus, through which power can be transmitted to the 3D glasses, a battery unit which powers the 3D glasses, and a charging unit, connected to the interface unit and the battery unit, which receives power input from the interface unit and charges the battery unit. 
         [0014]    The interface unit may be a universal serial bus (USB) interface unit. 
         [0015]    According to an aspect of another exemplary embodiment, there is provided a 3D display apparatus operating in association with 3D glasses, the 3D display apparatus including a power supply unit which supplies power, and an interface unit which is adapted to connect to the 3D glasses, and through which a charging voltage can be transmitted to the 3D glasses. 
         [0016]    The interface unit may preferably be a USB interface unit. 
         [0017]    According to an aspect of another exemplary embodiment, there is provided a 3D display apparatus operating in association with a plurality of 3D glasses, the 3D display apparatus including a power supply unit which supplies power, and a plurality of interface units, each of which is adapted to connect to one of the plurality of 3D glasses, and through each of which a charging voltage can be transmitted to the respective connected 3D glasses. 
         [0018]    The plurality of interface units may preferably be a USB interface unit. 
         [0019]    According to an aspect of another exemplary embodiment, there is provided a system for charging 3D glasses operating in association with a 3D display apparatus, the system including a 3D display apparatus, a USB cable, and at least one pair of 3D glasses connected to the 3D display apparatus through the USB cable, wherein the 3D glasses can be charged by a charging voltage supplied from the 3D display apparatus through the USB cable. 
         [0020]    According to an aspect of another exemplary embodiment, there is provided a system for charging 3D glasses, the system including a 3D display apparatus and 3D glasses, in which the 3D display apparatus wirelessly supplies a voltage to the 3D glasses, thus charging the 3D glasses in a contactless charging manner. 
         [0021]    The 3D display apparatus may include a primary coil, and the 3D glasses may include a secondary coil coupled magnetically to the primary coil of the 3D display apparatus to generate an induced electromotive force. The 3D glasses further includes a rectifier which rectifies the generated induced electromotive force into a direct current, and a voltage adjusting unit which adjusts the voltage of the rectified direct current to a constant voltage level. 
         [0022]    The secondary coil may be located in a frame of the 3D glasses. 
         [0023]    The primary coil may be located in one of a front portion, a rear portion, a side portion, and a lower portion of the 3D display apparatus. 
         [0024]    The 3D display apparatus may additionally include a 3D glasses holder disposed adjacent to the primary coil so that the 3D glasses can be laid thereon. The 3D glasses are chargeable with the induced electromotive force which is generated by a magnetic coupling between the primary coil and the secondary coil, when the 3D glasses are disposed in the 3D glasses holder. 
         [0025]    The primary coil may be located in a lower portion of the 3D display apparatus, and the 3D glasses are wirelessly chargeable with the induced electromotive force when the 3D glasses are within a predetermined distance of the primary coil. 
         [0026]    The primary coil may be located in a support supporting the 3D display apparatus, and the 3D glasses are wirelessly chargeable with the induced electromotive force when the 3D glasses are within a predetermined distance of the primary coil. 
         [0027]    According to an aspect of another exemplary embodiment, there is provided a system for charging 3D glasses operating in association with a 3D display apparatus, the system including 3D glasses, and a cradle which is connected to the 3D display apparatus, and which receives a voltage from the 3D display apparatus and wirelessly supplies the voltage to the 3D glasses, thus charging the 3D glasses in a contactless charging manner. 
         [0028]    The cradle may include a primary coil magnetically coupled to a secondary coil included in the 3D glasses to generate an induced electromotive force. 
         [0029]    The cradle may be formed in a configuration suitable to hold the 3D glasses therein, in which if the 3D glasses are held in the cradle, the 3D glasses are charged using a voltage supplied wirelessly from the cradle. 
         [0030]    The cradle may additionally include a USB interface unit which receives a voltage from the 3D display apparatus, in which the 3D glasses are charged wirelessly with a voltage supplied via the USB interface unit. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0031]    The above and/or other aspects will be more apparent by describing certain exemplary embodiments with reference to the accompanying drawings, in which: 
           [0032]      FIG. 1  illustrates a system for charging 3D glasses according to an exemplary embodiment; 
           [0033]      FIG. 2  is a block diagram of a 3D TV implementing a USB charging method according to an exemplary embodiment; 
           [0034]      FIG. 3  is a block diagram of 3D glasses implementing a USB charging method according to an exemplary embodiment; 
           [0035]      FIG. 4  illustrates a system for charging 3D glasses implementing a contactless charging method according to an exemplary embodiment; 
           [0036]      FIG. 5  is a block diagram of a 3D TV implementing a contactless charging method according to an exemplary embodiment; 
           [0037]      FIG. 6  is a block diagram of 3D glasses implementing a contactless charging method according to an exemplary embodiment; 
           [0038]      FIG. 7  is a circuit diagram of a charging unit of 3D glasses implementing a contactless charging method according to an exemplary embodiment; 
           [0039]      FIG. 8  illustrates a coil of 3D glasses implementing a contactless charging method according to an exemplary embodiment; 
           [0040]      FIGS. 9A and 9B  illustrate a structure of a system for charging 3D glasses implementing a contactless charging method according to an exemplary embodiment; and 
           [0041]      FIGS. 10A and 10B  illustrate a structure of a system for charging 3D glasses including a charging cradle according to an exemplary embodiment. 
       
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0042]    Certain exemplary embodiments will now be described in greater detail with reference to the accompanying drawings. 
         [0043]      FIG. 1  illustrates a charging system  100  of 3D glasses  120  according to an exemplary embodiment. As illustrated, the wireless charging system of the 3D glasses  120  may include a 3D television (TV)  100  which supplies power to charge the 3D glasses  120 , and a plurality of 3D glasses  120 - 1 ,  120 - 2 , . . . ,  120 - n  which are charged by the power supplied from the 3D TV  100 . 
         [0044]    The 3D TV  110  is a display apparatus, which receives a 3D image from a photographing device such as a camera, or from a broadcasting station where an image captured through a camera is edited and/or processed and transmitted, processes the received 3D image and displays the result. Particularly, the 3D TV  110  may process left-eye images and right-eye images with reference to the 3D image format, and cause the processed left- and right-eye images to be time-divided and displayed alternately. The 3D TV  110  may additionally generate a synchronous signal in sync with the timing with which the time-divide left- and right-eye images are displayed, and transmits the synchronous signal to the 3D glasses  120 . 
         [0045]    The 3D glasses  120  may open and close the left glass and the right glass alternately in accordance with the synchronous signal received from the 3D TV, allowing a user to view the left-eye images and the right-eye images through his left eye and right eye, respectively. 
         [0046]    In a system for charging 3D glasses according to an exemplary embodiment, the 3D TV  110  may be connected to a plurality of 3D glasses  120 - 1 ,  120 - 2 , . . . ,  120 - n  via a USB cable. Through the USB cable, the 3D TV  110  may supply power to the plurality of 3D glasses  120 - 1 ,  120 - 2 , . . . ,  120 - n , and the plurality of 3D glasses  120 - 1 ,  120 - 2 , . . . ,  120 - n  may be charged by the supplied power. 
         [0047]    Hereinbelow, a method of charging the 3D glasses  120  using a USB cable will be explained in greater detail, mainly with reference to  FIGS. 2 and 3 .  FIG. 2  is a block diagram of the 3D TV  110  according to an exemplary embodiment. 
         [0048]    Referring to  FIG. 2 , the 3D TV  110  according to an exemplary embodiment may include a function unit  111 , a power unit  112 , a plurality of USB interfaces  113 - 1 ,  113 - 2 , . . . ,  113 -N, and a control unit  114 . 
         [0049]    The function unit  111  may carry out general functions of the 3D TV  110 . Specifically, the function unit  111  may receive 3D broadcast content from the outside and reproduce the received 3D broadcast content. In particular, the function unit  111  may carry out functions such as tuning of a broadcast signal from a broadcast server such as a terrestrial broadcast, a cable or a satellite, decoding of the tuned broadcast signal and correcting of errors. The function unit  111  may additionally separate the decoded broadcast signal into video data, audio data and other additional data, and decode the respective data. If the received data is a 3D image, the function unit  111  may also separate the 3D image video data into left-eye images and right-eye images, and process the separate images respectively. The function unit  111  may then output the processed left- and right-eye images alternately, while outputting the audio data in sync with the images. 
         [0050]    The power unit  112  may provide the power to the respective components of the 3D TV  110  under the control of the control unit  114  which will be explained in detail below. Particularly, in order to charge the 3D glasses  120 , the power unit  112  may supply the power to the USB interface unit  113  which will be explained below. Typically, 220V AC power is supplied to a home 3D TV  110 , and the power unit  112  may convert the power into 5V direct current (DC) power to charge the 3D glasses  120  through the USB cable. 
         [0051]    The USB interface unit  113  may be connected to an external terminal device through the USB cable to supply power or exchange data. Particularly, the USB interface unit  113  may be connected to the 3D glasses  120  to supply a charging voltage to the 3D glasses  120 . In such a situation, the USB interface unit  113  may include a plurality of USB interface units  113 - 1 ,  113 - 2 , . . . ,  113 - n  to charge the plurality of 3D glasses  120 - 1 ,  120 - 2 , . . . ,  120 - n.    
         [0052]    Specifically, a USB connection may include a pair of power terminals 5V, GND, and a pair of data terminals D+, D−. Charging between the 3D TV  110  and the 3D glasses  120  through the USB cable may be achieved by the pair of power terminals 5V, GND. That is, if the 3D glasses  120  are connected to the 3D TV  110  through the USB cable, the 3D TV  110  supplies power to the 3D glasses  120  through the 5V terminal. 
         [0053]    The control unit  114  may control the overall operation of the 3D TV  110  according to a user command transmitted from a user operating unit (not illustrated). 
         [0054]    Particularly, the control unit  114  may control the power unit  112  and a plurality of USB interface units  113 - 1 ,  113 - 2 , . . . ,  113 - n  so that the 3D TV  110  charges the 3D glasses  120 . 
         [0055]    Additionally, if the 3D TV  110  is currently charging the 3D glasses  120  through the USB cable, the control  114  may control so that a graphical user interface (GUI) appears, indicating the current status in which the 3D glasses  120  are charged. 
         [0056]    Although the power is supplied through the USB in the example explained above with reference to  FIG. 2 , this is only for illustrative purposes. Accordingly, other types of interfaces may be implemented to supply power. 
         [0057]      FIG. 3  is a block diagram of the 3D glasses  120  according to an exemplary embodiment. Referring to  FIG. 3 , the 3D glasses  120  may include an infrared (IR) receiving unit  121 , a control unit  122 , a USB interface unit  123 , a charging unit  124 , a battery unit  125 , a driving unit  126 , and a glass unit  127 . 
         [0058]    The IR receiving unit  121  may receive a synchronous signal regarding a 3D image from a glasses signal transmitting and receiving unit (not illustrated) of the 3D TV  120 . Particularly, the glasses signal transmitting and receiving unit may irradiate a synchronous signal using the infrared ray with linearity, and the IR receiving unit  121  may receive a synchronous signal from the irradiated infrared ray. By way of example, the glasses signal transmitting and receiving unit may transmit an infrared ray with frequency of 60 Hz to the IR receiving unit  121 . 
         [0059]    The USB interface unit  123  may be connected to the USB interface unit  113  of the 3D TV  110  explained above, to charge the 3D glasses  120 . 
         [0060]    The USB interface unit  123  of the 3D glasses  120  may be connected to the 3D TV  110  and the pair of power terminals 5V, GND through the USB cable. The USB interface unit  123  may receive a charge voltage from the 3D TV  110  through the 5V terminal of the power terminals, and supply the received charge voltage to the charging unit  124 . 
         [0061]    The charging unit  124  may rectify or transform the charge voltage received from the USB interface unit  123  to a form suitable to charge the battery unit  125  which will be explained below. 
         [0062]    The battery unit  125  may supply power to the components of the 3D glasses  120  under the control of the control unit  122 . Particularly, the battery unit  125  may supply power to the 3D glasses  120  using the power charged in the manner explained above. The battery unit  125  may be a rechargeable battery or a super capacitor battery. 
         [0063]    The driving unit  126  may generate a driving signal based on a control signal received from the control unit  122 . Specifically, since the glass unit  127  includes the left glass and the right glass, the driving unit  126  may generate a left glass driving signal to drive the left glass and a right glass driving signal to drive the right glass respectively, and transmit the generated left and right glass driving signals to the left and right glasses, respectively. 
         [0064]    The glass unit  127 , including the left glass and the right glass as mentioned above, may open and close the respective left and right glasses in accordance with the driving signals received from the driving unit  126 . 
         [0065]    The control unit  122  may control the overall operations of the 3D glasses  120 . Specifically, the control unit  122  may generate a control signal based on an output signal received from the IR receiving unit  121 , and transmit the generated control signal to the driving unit  126  to control the driving unit  126  accordingly. 
         [0066]    The control unit  122  may additionally control the battery unit  125  to supply the power charged in the manner explained above to the components of the 3D glasses  120 . 
         [0067]    Since the 3D TV  110  may charge the plurality of 3D glasses  120 - 1 ,  120 - 2 , . . . ,  120 - n  in the manner explained above, there is no need for a separate charger, and the plurality of 3D glasses  120 - 1 ,  120 - 2 , . . . ,  120 - n  can be charged concurrently. 
         [0068]    A method of wirelessly charging 3D glasses using a contactless charging method according to an exemplary embodiment will be explained below, with reference to  FIGS. 4 to 10B . 
         [0069]      FIG. 4  illustrates a system for charging 3D glasses implementing a contactless charging method according to an exemplary embodiment. As illustrated in  FIG. 4 , the system for charging 3D glasses may include a 3D TV  410  and 3D glasses  420 . 
         [0070]    If the 3D glasses  420  are within a predetermined distance of the 3D TV  410 , the 3D glasses  420  may be charged by the power supplied from the 3D TV  410  in a contactless charging manner. The term ‘contactless charging method (manner)’ relates to charging a battery using electromagnetic induction generated between two parallel metal coils. The contactless charging will be explained in greater detail below with reference to  FIG. 7 . 
         [0071]      FIG. 5  is a block diagram of the 3D TV  410  implementing the contactless charging method according to an exemplary embodiment. Referring to  FIG. 5 , the 3D TV  410  may include a function unit  411 , a power unit  412 , a wireless charging unit  413 , and a control unit  414 . 
         [0072]    The function unit  411 , the power unit  412 , and the control unit  414  of  FIG. 5  will not be explained in detail below, as these are analogous to the function unit  111 , the power unit  112 , and the control unit  114  explained above with reference to  FIG. 2 . 
         [0073]    The wireless charging unit  413  may wirelessly charge the 3D glasses  420  using the power supplied from the power unit  412 . Since the wireless charging unit  413  may implement contactless charging, the wireless charging unit  413  may include a primary coil (transmitting coil) for electromagnetic induction. The wireless charging unit  413  may apply the power supplied from the power unit  412  to the primary coil, and supply the power of the 3D TV  410  to the 3D glasses  420  using the electromagnetic induction. 
         [0074]    The primary coil of the wireless charging unit  413  may be located in at least one of a front surface, a rear surface, and a side surface of the 3D TV  410 . Specifically, if a 3D glasses holder in which the 3D glasses  420  can be laid thereon is provided, the primary coil may be located in the 3D glasses holder. 
         [0075]    Alternatively, the primary coil may be located in a bottom side or a support of the 3D TV  410 . If the 3D glasses  420  are placed on the bottom side of the 3D TV  410  where there is the primary coil, the 3D glasses  420  are charged in a contactless charging manner. 
         [0076]      FIG. 6  is a block diagram of the 3D glasses  420  according to an exemplary embodiment. As illustrated in  FIG. 6 , the 3D glasses  420  may include an infrared ray (IR) receiving unit  421 , a control unit  422 , a wireless charging unit  423 , a battery unit  424 , a driving unit  425 , and a glass unit  426 . 
         [0077]    The IR receiving unit  421 , the control unit  422 , the battery unit  424 , the driving unit  425 , and the glass unit  426  of  FIG. 6  will not be explained in detail below, as these are analogous to the IR receiving unit  121 , the control unit  122 , the battery unit  125 , the driving unit  126 , and the glass unit  127  explained above with reference to  FIG. 3 . 
         [0078]    An electric current is generated due to electromagnetic induction generated between the primary coil of the wireless charging unit  413  of the 3D TV  410  and a secondary coil included in the wireless charging unit  423  of the 3D glasses  420 , and the wireless charging unit  423  charges the battery unit  424  using the generated electric current. 
         [0079]    The wireless charging unit  423  will be explained in greater detail below with reference to  FIG. 7 .  FIG. 7  schematically illustrates the wireless charging unit  423  according to an exemplary embodiment. 
         [0080]    As illustrated in  FIG. 7 , the 3D TV  410  may include the power unit  412 , and the primary coil  413 - 1 . The power unit  412  supplies a sine wave of power to the primary coil  413 - 1  so that the electricity flows through the primary coil  413 - 1 . As the electricity flows through the primary coil  413 - 1 , a magnetic field is generated around the primary coil  413 - 1 . 
         [0081]    The wireless charging unit  423  of the 3D glasses  420 , which is provided for the wireless charging with the 3D TV  410 , may include a secondary coil  423 - 1 , a rectifier  423 - 2 , and a voltage adjusting unit  423 - 3 . 
         [0082]    If the secondary coil  423 - 1  is placed close to the magnetic field generated from the primary coil  413 - 1  explained above, electricity flows through the second coil  423 - 1  due to electromagnetic induction. In other words, the magnetic coupling between the primary and the secondary coils  413 - 1 ,  423 - 1  causes induced electromotive force to be generated in the secondary coil  423 - 1 . In such a situation, the secondary coil  423 - 1  may be located in the frame of the 3D glasses  420  as illustrated in  FIG. 8 . 
         [0083]    The generated induced electromotive force may be rectified to DC by the rectifier  423 - 1 . The rectifier  423 - 1  may include four bridge diode-type diodes, and a capacitor for filtering. Of course, other forms of rectifying circuits beside the rectifier  423 - 1  explained above may be implemented according to an exemplary embodiment. Additionally, the voltage adjusting unit  423 - 3  may adjust the rectified DC voltage to a constant voltage level. 
         [0084]    The DC voltage, which is adjusted by the processes explained above into a constant voltage level, is supplied to the battery unit  424 . Accordingly, the battery unit  424  may supply power to the components of the 3D glasses  120  using the power charged in the manner explained above. 
         [0085]    Since it is possible to charge the 3D glasses  420  wirelessly, i.e., without requiring a cable, user convenience in charging the 3D glasses  420  increases significantly. 
         [0086]      FIGS. 9A and 9B  illustrate the structure of the 3D glasses implementing a contactless charging method according to an exemplary embodiment. 
         [0087]    Specifically,  FIG. 9A  illustrates the 3D glasses  420  being charged while the 3D glasses  420  are laid on the 3D glasses holder  430  on a predetermined portion of the 3D TV  410 . Referring to  FIG. 9A , the system for charging 3D glasses may include the 3D TV  410 , the 3D glasses  420 , and the 3D glasses holder  430 . The 3D glasses holder  430  may be located close to a right lower edge of the 3D TV  410 . Accordingly, if the 3D glasses  420  are laid on the 3D glasses holder  430 , the primary coil  413 - 1  and the secondary coil  423 - 1  are placed close to each other, and accordingly, the electromagnetic induction is generated. Due to the electromagnetic induction, the 3D glasses  420  are chargeable with the electricity of the 3D TV  410 . 
         [0088]    Although the 3D glasses holder  430  and the primary coil  413 - 1  are explained above as being located on the lower portion of the right side of the 3D TV  410 , this is only for illustrative purposes. Accordingly, the location of the 3D glass holder  430  and the primary coil  413 - 1  may be changed to, for example, an upper right portion, a lower left portion, an upper left portion, or a rear portion. 
         [0089]      FIG. 9B  illustrates the 3D glasses  420  being charged as the 3D glasses  420  are laid on a lower portion of the 3D TV  410 . Referring to  FIG. 9B , the system for charging 3D glasses may include the 3D TV  410  and the 3D glasses  420 . 
         [0090]    The 3D glasses  420  may be placed within a predetermined distance of a lower end of the 3D TV  410 . The term ‘predetermined distance’ relates to a distance within which the electromagnetic induction can be generated between the primary coil  413 - 1  of the 3D TV  410  and the secondary coil  423 - 1  of the 3D glasses  420 . The primary coil  413 - 1  may be located in a lower surface of the 3D TV  410 , or on a support  460  supporting the 3D TV  410 . If the 3D glasses  420  are placed within the predetermined distance of the support  460  of the 3D TV  410  or the lower surface of the 3D TV  410 , the electromagnetic induction is generated as the primary coil  413 - 1  of the 3D TV  410  and the secondary coil  423 - 1  of the 3D glasses  420  are placed close to each other. As a result, due to the electromagnetic induction, it is possible to charge the 3D glasses  420  using the power of the 3D TV  410 . 
         [0091]    Since the 3D glasses  420  are chargeable contactlessly, there is no need for a separate cable or charger to charge the 3D glasses  420 , and user can charge the 3D glasses  420  more conveniently and easily. 
         [0092]    The system for charging 3D glasses implementing a contactless charging method using a charging cradle  440  according to an exemplary embodiment will be explained below with reference to  FIGS. 10A and 10B . 
         [0093]    In contactless charging using the charging cradle  440 , the power unit  412  and the primary coil  413 - 1  explained above with reference to  FIG. 7  may be located in the charging cradle  440 . Accordingly, due to the electromagnetic induction generated between the primary coil  413 - 1  of the charging cradle  440  and the secondary coil  423 - 1  of the 3D glasses  420 , the 3D glasses  420  are charged. The manner of charging the 3D glasses  420  is explained above with reference to  FIG. 7 , and therefore, will not be repeated below. 
         [0094]      FIG. 10A  illustrates the structure of a system for charging 3D glasses which has the charging cradle  440  according to an exemplary embodiment. The system for charging 3D glasses according to this embodiment may include the 3D TV  410 , the 3D glasses  420 , and the charging cradle  440 . The charging cradle  440  may be attached to the rear portion of the 3D TV  410  as illustrated in  FIG. 10A . Additionally, the charging cradle  440  may be connected electrically to the 3D TV  410  to charge the 3D glasses  420  with the power supplied from the 3D TV  410 . 
         [0095]      FIG. 10B  illustrates the structure of a system for charging 3D glasses which has the charging cradle  440  according to an exemplary embodiment. In this embodiment, the system for charging 3D glasses may include the 3D TV  410 , the 3D glasses  420 , the charging cradle  440 , and a cable  450 . As illustrated in  FIG. 10B , the charging cradle  440  may be connected to the 3D TV  410  through the cable  450 . Accordingly, the charging cradle  440  may charge the 3D glasses  420  with the power supplied from the 3D TV  410 . The cable  450  may be implemented as a USB cable. Accordingly, the charging cradle  440  may include a USB interface unit (not illustrated) to connect the charging cradle  440  to the 3D TV  410  through the USB cable. 
         [0096]    As explained above, the user is able to charge the 3D glasses  420  more easily, by simply laying the 3D glasses  420  in the charging cradle  440 . 
         [0097]    Although the 3D TV  110  is explained as an example of a 3D display apparatus in the exemplary embodiments explained above, this is only for illustrative purposes. Accordingly, the technical concept of what is described herein is equally applicable to any 3D display apparatus which is capable of displaying shutter glass type 3D images. By way of example, a 3D projection or 3D monitor may be implemented as an example of the 3D display apparatus. 
         [0098]    As explained above, user convenience in charging the 3D glasses  120  increases because there is no need for a separate charging device. 
         [0099]    The foregoing exemplary embodiments and advantages are merely exemplary and are not to be construed as limiting the present inventive concept. The present teaching can be readily applied to other types of apparatuses. Also, the description of the exemplary embodiments is intended to be illustrative, and not to limit the scope of the claims, and many alternatives, modifications, and variations will be apparent to those skilled in the art.