Abstract:
A projector and method of controlling a projector, the projector including: a projection unit configured to project an image; first and second sensors which are disposed to be centered about the projection unit and configured to detect a motion of an object; and a control unit configured to control the projector if the motion of the object is detected by at least one of the first and the second sensors, wherein an axis of detection of the first sensor intersects an axis of detection of the second sensor.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority from Korean Patent Application No. 10-2011-0048057, filed May 20, 2011, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety. 
       BACKGROUND 
       [0002]    1. Field 
         [0003]    Apparatuses and methods consistent with the present inventive concept relate to a projector and a control method thereof, and more particularly to a projector and a control method thereof, which can detect a person approaching a projection region of the projector or existing therein thus to prevent her vision from being impaired. 
         [0004]    2. Description of the Related Art 
         [0005]    A projector, a projection system or the like is a display apparatus, which projects received image signals onto a screen by using a light emitted from a light source (for example, a light emitting diode (LED) or a lamp) thus to show images. Such a display apparatus is used, for example, in a presentation in a conference room, or in a motion picture projector at a theater, or in a home theater, etc. 
         [0006]    The light source provided in the projector emits a projection light when it is supplied with electric power. The projection light emitted from the projector is very strong, i.e., intense, and if a person looks directly at a lens of the projector during operation of the projector, her vision may be worsened, and if exposed to the projection light for a long period of time, her vision may be impaired. 
         [0007]    A projector with a protection circuit has been recently proposed, which detects a projection area of the projection light using a sensor and which stops the projection operation, or reduces the strength of the projection light if a person is detected within the projection area. 
         [0008]    However, in the case of an ultra-short focus projector, since an angle of projection of the projection light is wider than that of general projectors, there is a problem in that it is difficult to detect the existence or the approach of the person in the projection area of the projector using the related art detecting method. 
       SUMMARY 
       [0009]    Exemplary embodiments may overcome the above disadvantages and other disadvantages not described above. However, an exemplary embodiment is not required to overcome the disadvantages described above, and an exemplary embodiment may not overcome any of the problems described above. 
         [0010]    According to an aspect of an exemplary embodiment, there is provided a projector which may include: a projection unit configured to project an image; first and second sensors which are disposed to be centered about the projection unit and configured to detect a motion of an object; and a control unit configured to control the projector if the motion of the object is detected by at least one of the first and the second sensors, wherein an axis of detection of the first sensor intersects an axis of detection of the second sensor. 
         [0011]    The first sensor may be disposed on a left of the projection unit and may be configured to detect a right region and a center region of the projection area, and the second sensor may be disposed on a right of the projection unit and may be configured to detect a left region and the center region of the projection area. 
         [0012]    The axis of detection of the first sensor may form an angle of 30 to 50 degrees with a center axis of projection. 
         [0013]    The axis of detection of the first sensor may form an angle of 5 to 15 degrees with a center axis of projection. 
         [0014]    The axis of detection of the first sensor may intersect a first point on an right side with respect to a screen point intersecting a center axis of projection, and the axis of detection of the second sensor may intersect a second point on an left side with respect to the screen point intersecting the center axis of projection. 
         [0015]    The control unit may control the projection unit to turn off a projection light if the motion of the object is detected by the at least one of the first and the second sensors. 
         [0016]    The control unit may control the projection unit to reduce a projection light if the motion of the object may be detected by the at least one of the first and the second sensors. 
         [0017]    The projector may further include: a storing unit configured to store a message; and an output unit configured to output the message stored in the storing unit, wherein the control unit may control the output unit to output the message if the motion of the object is detected by the at least one of the first and the second sensors. 
         [0018]    The projector may be an ultra-short focus projector. 
         [0019]    The first and the second sensors may include pyro-electric infrared sensors, respectively. 
         [0020]    According to an aspect of an exemplary embodiment, there is provided a method of controlling a projector including a projection unit, wherein the method may include: projecting an image by the projection unit; detecting a motion of an object by at least one of a first and second sensor which are respectively disposed to be centered about the projection unit; and controlling the projector if the motion of the object is detected by the at least one of the first and the second sensors, wherein an axis of detection of the first sensor may intersect an axis of detection of the second sensor. 
         [0021]    The first sensor may be disposed on a left of the projection unit and may be configured to detect a right region and a center region of the projection area, and wherein the second sensor may be disposed on a right of the projection unit and is configured to detect a left region and the center region of the projection area. 
         [0022]    The axis of detection of the first sensor may form an angle of 30 to 50 degrees with a center axis of projection. 
         [0023]    The axis of detection of the first sensor may form an angle of 5 to 15 degrees with a center axis of projection. 
         [0024]    The axis of detection of the first sensor may intersect a first point on an right side with respect to a screen point intersecting a center axis of projection, and wherein the axis of detection of the second sensor may intersect a second point on an left side with respect to the screen point intersecting the center axis of projection. 
         [0025]    The controlling may include turning off a projection light projecting the image if the motion of the object is detected by at least one of the first and the second sensors. 
         [0026]    The controlling may include reducing a projection light projected by the projector in strength if the motion of the object is detected by at least one of the first and the second sensors. 
         [0027]    The method may further include: outputting a previously stored message if the motion of the object is detected by the first and the second sensors. 
         [0028]    According to an aspect of an exemplary embodiment, there is provided a projector which may include: a projection unit configured to project a light; a plurality of sensors disposed about a center axis of projection of the light projected by the projection unit, wherein each of plurality of sensors is configured to detect a motion of a person within a predetermined detection space; and a control unit configured to control an operation of the projector if the motion of the person is detected by at least one of the plurality of sensors, wherein a detection space of a first sensor of the plurality of sensors may cover at least a portion of a detection space of a second sensor of the plurality of sensors. 
         [0029]    The light projected by the projection unit is projected within a projection space, wherein the first sensor may be disposed on a left of the projection space and the second sensor may be disposed on a right of the projection space. 
         [0030]    A total detection space including the detection space of the first sensor and the detection space of the second sensor may substantially cover the projection space. 
         [0031]    An axis of detection of the first sensor may intersect a first point within the projection space which is on a right of a center point intersected by the center axis of projection, and an axis of detection of the second sensor may intersect a second point within the projection space which is on a left of the center point intersected by the center axis of projection. 
         [0032]    The operation of the projector controlled by the control unit may include turning off the light projected by the projection unit. 
         [0033]    The object detected may be a person. 
         [0034]    The first and second sensors may further be disposed opposite to the projection unit. 
         [0035]    According to an aspect of an exemplary embodiment, there is provided a projector which may include: a projection unit configured to project a light within a projection area; a plurality of sensors disposed about a center axis of projection of the light projected by the projection unit, wherein each of plurality of sensors is configured to detect motion via one of temperature and heat changes within a predetermined detection area; and a control unit configured to control the projecting of the light by the projection unit if the motion is detected by at least one of the plurality of sensors, wherein a detection area of a first sensor of the plurality of sensors overlaps at least a portion of a detection area of a second sensor of the plurality of sensors. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0036]    The above and/or other aspects will become more apparent by describing certain exemplary embodiments with reference to the accompanying drawings, in which: 
           [0037]      FIG. 1  is a block diagram view showing a configuration of a projector according to an exemplary embodiment; 
           [0038]      FIG. 2  is a side view showing a projection space/area of the projector according to an exemplary embodiment; 
           [0039]      FIG. 3  is a top view showing the projection space/area of the projector according to an exemplary embodiment; 
           [0040]      FIGS. 4 to 6  are views showing a detection area according to exemplary embodiments; 
           [0041]      FIG. 7  is a view showing a screen point to an axis of detection and a center axis of projection according to an exemplary embodiment; 
           [0042]      FIG. 8  is a flowchart showing a control method of the projector according to an exemplary embodiment; and 
           [0043]      FIG. 9  is a flowchart for explaining a detecting operation and a protection mode operation in  FIG. 8 . 
       
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0044]    Exemplary embodiments are described in greater detail below with reference to the accompanying drawings. 
         [0045]      FIG. 1  is a block diagram view showing a configuration of a projector according to an exemplary embodiment. 
         [0046]    Referring to  FIG. 1 , the projector  100  includes a telecommunication interface unit  110 , a projection unit  120 , a storing unit  130 , an output unit  140 , a detection unit  150 , and a control unit  160 . Here, the projector  100  may be an ultra-short focus projector. 
         [0047]    The communication interface unit  110  is formed for connecting the projector  100  with outer appliances (not shown), and may be embodied in a form where it is connected by a universal serial bus (USB) port and a wireless communication method, as well as a form where it is connected to the outer appliances through a local area network (LAN) or an internet network. 
         [0048]    If the projector  100  has a function capable of receiving and outputting broadcasting signals, the communication interface unit  110  may receive broadcasting by wire or radio from a satellite or a broadcasting station and demodulate it. The communication interface unit  110  may divide the received broadcasting signals into video signals, audio signals, and broadcasting information, and may image-process the divided video signals to be transmitted to the projection unit  120  and audio-process the divided audio signals to be transmitted to the output unit  140 . 
         [0049]    The projection unit  120  projects images. To be more specific, the projection unit  120  may project images transmitted from the communication unit  110  or images stored in advance in the storing unit  130  by using a light source, such as a lamp or a light emitting diode (LED). Detailed configuration and operation on the projection unit  120  will be described later with reference to  FIG. 2 . 
         [0050]    The storing unit  130  may store contents received from or broadcasting signals processed by the communication interface unit  110 . The storing unit  130  may also store a message. The storing unit  130  may be embodied by a memory, for example, a read only memory (ROM), a flash memory, or a hard disk drive (HDD), mounted in the projector  100 , or by an external HDD or a memory card, for example, a flash memory (M/S, XD, SD, etc.) or a USB memory, connected with the projector  100 . 
         [0051]    In this case, the message may be a warning message, and may include a message informing a user that she is exposed to a projection light of the projector. This message may include an animation massage, a text message and/or a voice message, for example. 
         [0052]    The output unit  140  outputs the message. For example, the output unit  140  may include a speaker or a display panel, and if the message is the text message, may display corresponding texts on the display panel and if it is the voice message, may output corresponding voice through the speaker. Although an exemplary embodiment has been explained only as outputting the message through the output unit  140 , other exemplary embodiments may include outputting the message through the projection unit  120 . 
         [0053]    The detection unit  150  detects an existence or a motion of an object (or person) within a projection space or area of the projection unit  120 . For example, the detection unit  150  may include first and second sensors  131  and  132  disposed opposite thereto and are centered thereabout. In this case, the first and the second sensors  131  and  132  may be made up of pyro-electric infrared (PIR) sensors, respectively. If the PIR sensors as the first and the second sensors are used as described above, they may detect only a motion of a target via temperature or heat, thereby preventing an error from occurring, for example, preventing them from detecting whether or not there is an object other than a person. Although in the exemplary embodiment, the detection unit  150  has been explained as using the PIR sensors as the first and the second sensors, other exemplary embodiments may include a case where the detection unit  150  uses sensors other kinds of sensors for the first and the second sensors. 
         [0054]    The control unit  160  is capable of controlling many components in the projector  100 . The control unit  160  may control the projection unit  120  to project the images according to a control command of the user, and control the detection unit  150  to detect whether or not there is motion of the object within the projection area. 
         [0055]    If there is motion of the object in the projection area, the control unit  160  may control the projector to be operated in a protection mode. Here, the protection mode is an operation where the projector turns off the projection light, reduces the projection light in strength, outputs a certain message, etc. For example, if the motion of the object is detected through the first and the second sensors  131  and  132 , the control unit  160  may control the projection unit  120  to turn off the projection light thereof or reduce a strength of the projection light. In addition, the control unit  160  may control the output unit  140  to output the message stored in advance in the storing unit  130 . This message outputting operation may be carried out along with the operation of turning off the projection light or reducing a strength of the projection light. 
         [0056]    As described above, the projector  100  according to an exemplary embodiment can detect a person approaching the projection area or existing therein, and if the approach or the existence of the person is detected, can operate in the protection mode to prevent an accident due to the projection light. 
         [0057]      FIG. 2  is a side view showing a projection area of the projector according to an exemplary embodiment. 
         [0058]    Referring to  FIG. 2 , the projector  100  is an ultra-short focus projector, which projects light for images. For example, the projector  100  projects the light according to the images toward a screen  10  via a mirror, and thus the light of the projected image is projected onto the screen  10 . 
         [0059]      FIG. 3  is a top view showing an example of the projection area of the projector according to an exemplary embodiment. Hereinafter, to facilitate explanation, a direction parallel with the screen is referred as an “X” direction, and a direction vertical to the X direction (i.e., a direction toward the screen) is referred as an “Y” direction. 
         [0060]    Referring to  FIG. 3 , a projection area  210  to which the light is projected from the ultra short focus projector  100  has an angle of projection wider than that of the projection area of the related art projector. To detect such a wide projection area  210 , the detection unit  150  according to an exemplary embodiment is provided with the first and the second sensors  131  and  132  disposed opposite to the projection unit  120  or  200 , and centered with respect to the projection unit  120  or  200 . 
         [0061]    Here, the first sensor  131  is disposed on the left side of the projection unit  200  in the X direction, and detects the motion of the object to a right region and a center region of the projection area  210 . The second sensor  132  is disposed on the right side of the projection unit  200  in the X direction, and detects the motion of the object to a left region and the center region of the projection area  210 . The detection areas of the first and the second sensors  131  and  132  will be described later with reference to  FIGS. 4 to 6 . 
         [0062]    Although in the explanation on  FIG. 3 , the first and the second sensors  131  and  132  have been explained as being disposed on the same line (i.e., the same X axis) with respect to the projection unit  200 , they may be disposed on or near the rear of the projection unit  200  (i.e., the Y direction) with respect to the screen  10 . Also, although the first and the second sensors  131  and  132  have been explained as being directly disposed adjacent to the projection unit  200  in the direction of the X axis, they may be disposed apart from the projection unit  200  in the same direction of the X axis. 
         [0063]    Hereinafter, the detection areas of the first and the second sensors  131  and  132  will be described with reference to  FIGS. 4 to 6 . 
         [0064]      FIG. 4  is a top view showing the detection area of the projector according to an exemplary embodiment. 
         [0065]    Referring to  FIG. 4 , the first sensor  131  is disposed on the left of the projection unit  120 , and detects the center region and the right region of the projection area  210 . For example, an axis  530  of detection of the first sensor  131  intersects a right area of the screen  10  with respect to a center axis  220  of projection, and the detection area  540  of the first sensor  131  is from a first axis  510  to a second axis  520 . Here, an angle between the first axis  510  and the second axis  520  may be approximately 80 degrees. In addition, the axis  530  of detection of the first sensor  131  may form an angle α of 30 to 50 degrees in a horizontal direction, for example, with the center axis  220  of projection, i.e., about which images are projected from the projection unit  200  ( 120  of  FIG. 1 ). Such an angle between the first axis  510  and the second axis  520  is typical of a detecting angle of the general PIR sensors, however PIR sensors may have different detecting angles, or other sensors may be used which may have varying detecting angles. 
         [0066]    The second sensor  132  is disposed on the right of the projection unit  120 , and detects the center region and the left region of the projection area  210 . For example, an axis  430  of detection of the second sensor  132  intersects a point at a left area of the screen  10  with respect to the center axis  220  of projection, and the detection area  440  of the second sensor  132  is from a third axis  410  to a fourth axis  420 . Here, an angle between the third axis  410  and the fourth axis  420  may be approximately 80 degrees. In addition, the axis  430  of detection of the second sensor  132  may form an angle of 30 to 50 degrees in the horizontal direction, for example, with the center axis  220  of projection, which projects the images from the projection unit  200 . Such an angle between the third axis  410  and the fourth axis  420  is typical of the detecting angle of the general PIR sensors, however PIR sensors may have different detecting angles, or other sensors may be used which may have varying detecting angles. 
         [0067]    As described above, the first and the second sensors  131  and  132  are arranged so that the axes of detection intersect each other, thereby allowing the first and the second sensors  131  and  132  to maximally cover the projection area  210  of the projector  100 . 
         [0068]      FIGS. 5 and 6  are alternative views showing the projection area of the projector according to exemplary embodiments. Hereinafter, to facilitate explanation, an up and down direction of the projector is referred as a “Z” direction. 
         [0069]    Referring to  FIGS. 5 and 6 , the axes  530  and  430  of detection of the first and the second sensors  131  and  132  have the same angle in the Z direction. At this time, an angle β between the axes  530  and  430  of detection and the center axis  220  of projection, which projects the images from the projection unit  200 , forms an angle of 5 to 15 degrees in a vertical direction, for example. 
         [0070]    As described above, the detection areas of the first and the second sensors  131  and  132  may be located at various places with respect to the projection space or area  210  of the projection unit  120 , thereby easily detecting the movement of a user with respect to the projector  100 . 
         [0071]      FIG. 7  is a view showing a screen point to the axis of detection and the center axis of projection according to an exemplary embodiment. 
         [0072]    Referring to  FIG. 7 , the axis  530  of detection of the first sensor  131  intersects a first point  730  on an upper right side with respect to a screen point  710  intersecting the center axis  220  of projection, about which images are projected by the projection unit  200 . 
         [0073]    The axis  430  of detection of the second sensor  132  intersects a second point  720  on an upper left side with respect to the screen point  710  intersecting the center axis  220  of projection, about which images are projected by the projection unit  200 . 
         [0074]      FIG. 8  is a flowchart showing a control method of the projector according to an exemplary embodiment. 
         [0075]    Referring to  FIG. 8 , images are first projected (S 810 ). For example, the images may be projected onto the screen  10  by using the light source, such as a lamp or an LED. 
         [0076]    Further, a motion of an object is detected through the first and the second sensors disposed opposite to the projection unit, and centered with respect to the projection unit (S 820 ). Since the operation of detecting the motion of the object using the first and the second sensors is explained above with reference to the detection unit  150  of  FIGS. 1 and 4  to  7 , a redundant explanation thereon will be omitted. 
         [0077]    When the motion of the object is detected by the first and the second sensors, the projector operates in a protection mode (S 830 ). For example, if motion of the object is detected through the first and the second sensors, the projector may be operated so as to turn off a projection light, which projects the images, or to reduce a strength of the projection light. Additionally, the projector may inform a user of the previously stored message. 
         [0078]      FIG. 9  is a flowchart for explaining the detecting operation and the protection mode operation, an example of which is shown in  FIG. 8 , in more detail. 
         [0079]    Referring to  FIG. 9 , first, when detection signal levels are output from the first and the second sensors (S 905 ), it is determined whether any of the detection signal levels are larger than a predetermined signal value (S 910 ). The predetermined signal value may be a signal value provided from a manufacturing company, and may be an experimental value which corresponds to a temperature measured of the person or from heat emitted by the person. Such a detecting operation may be carried out in real time or each predetermined time (for example, 0.5 seconds) 
         [0080]    If any of the detected signal levels are larger than the predetermined signal value, the projector operates in the protection mode (S 915 ). For example, a warning phrase (or message) may be displayed on the screen (S 916 ), a warning alarm may be output through the speaker (S 918 ), or the strength of the projection light may be reduced (S 917 ). 
         [0081]    After entering the protection mode, detection signal levels are received from the first and the second sensors again (S 920 ), and it is determined whether any of the detection signal levels are larger than the predetermined signal value (S 925 ). 
         [0082]    If any of the detected signal levels are not larger than the predetermined signal value (S 925 -N), the protection mode may be lifted (S 930 ). 
         [0083]    If any of the detected signal levels are larger than the predetermined signal value (S 925 -Y), it is determined whether an operation time for the protection mode exceeds a predetermined time (S 935 ), and if it exceeds the predetermined time, the projection light may be turned off (S 940 ). Although in the exemplary embodiment the turnoff operation has been explained as turning off the projection light only when the operation time for the protection mode exceeds the predetermined time, it may be embodied in a form where if the detected signal levels is larger than the predetermined signal value, the projection light is turned off directly. 
         [0084]    Accordingly, the control method of the projector according to an exemplary embodiment may detect the person approaching the projection area or existing therein, and if the approach or the existence of the person is detected, the projector may operate in the protection mode, thereby preventing an accident due to the projection light. The examples of the control methods of the projector shown in  FIGS. 8 and 9  may be applied to and executed, for example, by the projector having the configuration of  FIG. 1 , but also by projectors having other configurations. 
         [0085]    As described above, although the present inventive concept has been explained by the exemplary embodiments, it is not limited to the foregoing exemplary embodiments. The present teaching can be readily applied to other types of apparatuses and many alternatives, modifications, and variations will be apparent to those skilled in the art.