Patent Publication Number: US-2010110006-A1

Title: Remote pointing appratus and method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the priority benefit of Korean Patent Application No. 10-2008-0107832, filed on Oct. 31, 2008, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
     BACKGROUND 
     1. Field 
     Exemplary embodiments relate to an infrared-ray (IR)-based pointing apparatus and method which controls a location of a cursor on a display. 
     2. Description of the Related Art 
     A pointing system controlling a location of a cursor on a display is currently the focus of attention due to the advent of an intelligent television (TV), and the like. In an initial model of the intelligent TV, an option provided on a display may be associated with a button of a remote control, or an activation portion on a screen may change using a direction button (left/right, top/bottom). 
     However, in a conventional art, a button may not effectively control a movement of a pointer/cursor on a display similar to a natural movement of a computer mouse. Accordingly, a method of naturally mapping a movement of a pointing apparatus to a movement of a pointer/cursor on a display, when a user moves the pointing apparatus, is required. 
     SUMMARY 
     Additional aspects and/or advantages will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the disclosure. 
     Exemplary embodiments may provide a remote pointing apparatus and method which may reduce complexity of a circuit configuration and an effect of noise. 
     Exemplary embodiments may also provide a frequency-modulated remote pointing apparatus and method which may be utilized for quick calculations without a control signal. 
     According to exemplary embodiments, there may be provided a remote pointing apparatus, including: a light receiving unit to receive a first emitted light and a second emitted light emitted during a first half cycle, and a third emitted light and a fourth emitted light emitted during a second half cycle; and a calculation unit to compare amplitudes of the received first emitted light and the received second emitted light to calculate a first coordinate axis value of a cursor on a display unit, and compare amplitudes of the received third emitted light and fourth emitted light to calculate a second coordinate axis value of the cursor on the display unit. 
     The light receiving unit may receive a control signal emitted every cycle, and the calculation unit may divide a cycle into the first half cycle and the second half cycle based on a time that the control signal is received. 
     According to exemplary embodiments, the first emitted light and the second emitted light may have an identical cycle and an identical amplitude, and each of the first emitted light and the second emitted light may be a pulse train with a first phase difference of a first angle. Also, the third emitted light and the fourth emitted light may have an identical cycle and an identical amplitude, and each of the third emitted light and the fourth emitted light may be a pulse train with a second phase difference with a second angle. The first angle and the second angle may be 180 degrees. 
     According to other exemplary embodiments, the first emitted light may be a signal of a ramp downward sawtooth wave, the second emitted light may be a signal of an upward ramp sawtooth waveform, and the first emitted light and the second emitted light may have an identical cycle and an identical maximum amplitude. The downward ramp sawtooth waveform of the first emitted light and the upward ramp sawtooth waveform of the second emitted light may be embodied as a pulse train. In this instance, a phase difference between the pulse trains of the first emitted light and the second emitted light may be 180 degrees. When the amplitude of the first emitted light increases from 0 to a maximum amplitude, the amplitude of the second emitted light may decrease from a maximum amplitude to 0. 
     Also, the third emitted light may be a signal of a downward ramp sawtooth waveform, the fourth emitted light may be a signal of a upward ramp sawtooth waveform, and the third emitted light and the fourth emitted light may have an identical cycle and an identical maximum amplitude. The third emitted light and the fourth emitted light may be emitted after the control signal is generated, that is, a time of (t 1 −t 0 ). 
     According to exemplary embodiments, the first emitted light may be a ramp downward pulse train signal, the second emitted light may be an upward ramp pulse train signal, and the calculation unit may calculate the first coordinate axis value of the cursor based on a time that intensities of the first emitted light and the second emitted light are identical. 
     The third emitted light may be a ramp downward pulse train signal, the fourth emitted light may be an upward ramp pulse train signal, and the calculation unit may calculate the second coordinate axis value of the cursor based on a time that intensities of the third emitted light and the fourth emitted light are identical. 
     According to still other exemplary embodiments, a remote pointing apparatus, including: a modulator to generate at least four emitted lights having a same amplitude and different frequencies; and at least four light emitting units to emit each of the at least four emitted lights. 
     The at least four emitted lights may include a first emitted light, a second emitted light, a third emitted light, and a fourth emitted light, and the first emitted light and the second emitted light may have a same amplitude and the third emitted light and the fourth emitted light may have a same amplitude. The first emitted light, the second emitted light, the third emitted light and the fourth emitted light may be an infrared-ray. 
     According to exemplary embodiments, a remote pointing apparatus, including: a filtering unit to filter a received signal to a first frequency component, a second frequency component, a third frequency component, and a fourth frequency component; and a calculation unit to compare amplitudes of the first frequency component and the second frequency component to calculate a first coordinate axis value of a cursor on a display unit, and compare amplitudes of the third frequency component and the fourth frequency component to calculate a second coordinate axis value of the cursor on the display unit. 
     According to exemplary embodiments, a remote pointing method, including: emitting a first emitted light and a second emitted light during a first half cycle; receiving the first emitted light and the second emitted light during the first half cycle and calculating a first coordinate axis value of a cursor on a display unit; emitting a third emitted light and a fourth emitted light during a second half cycle; and receiving the third emitted light and the fourth emitted light during the second half cycle and calculating a second coordinate axis value of the cursor on the display unit. 
     According to other exemplary embodiments, the remote pointing method may further include: emitting a control signal every cycle, wherein a cycle may be divided into the first half cycle and the second half cycle based on a time that the control signal is received. 
     According to still other exemplary embodiments, a remote pointing method, including: receiving a first emitted light modulated to a first frequency, a second emitted light modulated to a second frequency, a third emitted light modulated to a third frequency, and a fourth emitted light modulated to a fourth frequency in a light receiving unit; filtering the lights received in the light receiving unit to a first frequency component, a second frequency component, a third frequency component, and a fourth frequency component; and comparing amplitudes of the first frequency component and the second frequency component to calculate a first coordinate axis value of a cursor on a display unit, and comparing amplitudes of the third frequency component and the fourth frequency component to calculate a second coordinate axis value of the cursor on the display unit. 
     The first emitted light and the second emitted light may have a same amplitude and the third emitted light and the fourth emitted light may have a same amplitude. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and/or other aspects of exemplary embodiments will become apparent and more readily appreciated from the following description, taken in conjunction with the accompanying drawings of which: 
         FIG. 1  is a diagram illustrating an apparatus for transmitting an emitted light according to exemplary embodiments; 
         FIG. 2  is a diagram illustrating coordinates of a cursor on a display according to exemplary embodiments; 
         FIG. 3  is a block diagram illustrating a remote pointing apparatus according to exemplary embodiments; 
         FIG. 4  is a diagram illustrating pulse trains of emitted lights according to exemplary embodiments; 
         FIG. 5  is a diagram illustrating waveforms when receiving the emitted lights of  FIG. 4 ; 
         FIG. 6  is a diagram illustrating sawtooth waveforms of emitted lights according to exemplary embodiments; 
         FIG. 7  is a diagram illustrating waveforms when receiving the emitted lights of  FIG. 6 ; 
         FIG. 8  is a diagram illustrating emitted ramp signal lights according to exemplary embodiments; 
         FIG. 9  is a diagram illustrating waveforms when receiving the emitted lights of  FIG. 8 ; 
         FIG. 10  is a diagram illustrating emitted frequency-modulated lights according to exemplary embodiments; 
         FIG. 11  is a diagram illustrating waveforms when receiving the emitted lights of  FIG. 10 ; and 
         FIG. 12  is a flowchart illustrating a remote pointing method according to exemplary embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to exemplary embodiments, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. Exemplary embodiments are described below to explain the present disclosure by referring to the figures. 
       FIG. 1  is a diagram illustrating an apparatus  100  for transmitting an emitted light according to exemplary embodiments. 
     A control unit  110  may control a first light emitting unit  121 , a second light emitting unit  122 , a third light emitting unit  123 , and a fourth light emitting unit  124  to emit a first emitted light, a second emitted light, a third emitted light, and a fourth emitted light. When an operation command is transmitted by a user, the control unit  110  may control the first light emitting unit  121 , the second light emitting unit  122 , the third light emitting unit  123 , and the fourth light emitting unit  124  according to a predetermined scheme. 
     Waveforms of emitted lights emitted under control of the control unit  110  are described in detail with reference to  FIG. 4 ,  FIG. 6 ,  FIG. 8 , and  FIG. 10 . 
     At least one of the first light emitting unit  121 , the second light emitting unit  122 , the third light emitting unit  123 , and the fourth light emitting unit  124  may be an infrared-ray light-emitting diode (IR LED). 
     The first light emitting unit  121  may emit the first emitted light towards a right side by a predetermined angle in a front side of the apparatus  100  for transmitting an emitted light (hereinafter, the apparatus  100 ). Accordingly, when the apparatus  100  faces a receiving unit, the first emitted light may be emitted to a right side of the receiving unit. Also, as the apparatus  100  faces left, the first emitted light may be emitted to the receiving unit more strongly. 
     The second light emitting unit  122  may emit the second emitted light towards a left side by a predetermined angle in the front side of the apparatus  100 . Accordingly, when the apparatus  100  faces the receiving unit, the second emitted light may be emitted to a left side of the receiving unit. Also, as the apparatus  100  faces right, the second emitted light may be emitted to the receiving unit more strongly. 
     The third light emitting unit  123  may emit the third emitted light downwards by a predetermined angle in the front side of the apparatus  100 . Accordingly, when the apparatus  100  faces the receiving unit, the third emitted light may be emitted to a lower part of the receiving unit. Also, as the apparatus  100  faces upwards, the third emitted light may be emitted to the receiving unit more strongly. 
     The fourth light emitting unit  124  may emit the third emitted light upwards by a predetermined angle in the front side of the apparatus  100 . Accordingly, when the apparatus  100  faces the receiving unit, the fourth emitted light may be emitted to an upper part of the receiving unit. Also, as the apparatus  100  faces downwards, the fourth emitted light may be emitted to the receiving unit more strongly. 
     According to other exemplary embodiments, the second light emitting unit  122  may simultaneously function as any one of the third light emitting unit  123  and the fourth light emitting unit  124 . In this instance, when the apparatus  100  faces the receiving unit, the second light emitted light may be emitted to the front side of the receiving unit. Hereinafter, although the first light emitting unit  121 , the second light emitting unit  122 , the third light emitting unit  123 , and the fourth light emitting unit  124  are described, a light emitting unit may not be limited to the exemplary embodiments. According to still other exemplary embodiments, the second light emitting unit  122  may emit the second emitted light during a first half cycle, and the third emitted light during a second half cycle, and thus the third light emitting unit  123  may be omitted. 
     According to exemplary embodiment, a modulator  130  may modulate the first emitted light, the second emitted light, the third emitted light, and the fourth emitted light to a first frequency, a second frequency, a third frequency, and a fourth frequency. The modulator  130  may include an oscillator. However, amplitudes of the first emitted light modulated to the first frequency, and the second emitted light modulated to the second frequency, may be identical. The modulator  130  and the control unit  110  may adjust the amplitudes. The third emitted light modulated to the third frequency, and the fourth emitted light, modulated to the fourth frequency, may have a same amplitude. 
     The operation order of the user may be transmitted through a button  140  according to exemplary embodiments. The apparatus  100  may be activated and operated while the user pushes the button  140 . 
       FIG. 2  is a diagram illustrating coordinates of a cursor on a display according to exemplary embodiments. 
     A cursor  230  may be on a display  200  such as a television (TV), Plasma Display Panel (PDP), Liquid Crystal Display (LCD) panel, and the like. Although the cursor  230  is illustrated as  FIG. 2 , any form which may indicate a particular point on a screen may be the cursor  230 . 
     The cursor  230  may be used for a user to click a particular point on the display  200 . Coordinates of the cursor  230  may be (x 1 , y 1 ). Here, x 1  may be a value of a first coordinate axis  210 , hereinafter, x axis, and y 1  may be a value of a second coordinate axis  220 , hereinafter, y axis. 
     According to exemplary embodiments, a user may indicate the coordinates of the cursor  230 , (x 1 , y 1 ), on the display  200  through a remote control. 
     A light receiving unit  240  may receive a signal such as an IR signal, transmitted from the remote control. The light receiving unit  240  is described in detail with reference to  FIG. 3 . 
       FIG. 3  is a block diagram illustrating a remote pointing apparatus  300  according to exemplary embodiments. 
     According to exemplary embodiments, the remote pointing apparatus  300  may be embodied as a circuit module included in a circuit of the display  200  of  FIG. 2 . 
     A light receiving unit  310  may correspond to the light receiving unit  240  of  FIG. 2 . 
     The light receiving unit  310  may receive a first emitted light, a second emitted light, a third emitted light, and a fourth emitted light. Each of the first emitted light, the second emitted light, the third emitted light, and the fourth emitted light may be emitted in the first light emitting unit  121 , the second light emitting unit  122 , the third light emitting unit  123 , and the fourth light emitting unit  124  of  FIG. 1 . 
     According to exemplary embodiments, the first emitted light and the second emitted light may be received during a first half cycle, and the third emitted light and the fourth emitted light may be received during a second half cycle. Also, a control signal may be received when receiving the first emitted light, the second emitted light, the third emitted light, and the fourth emitted light, which are periodic waves. In this instance, a waveform of each of the four emitted lights is described in detail with reference to  FIG. 4 ,  FIG. 6 , and  FIG. 8 . 
     According to other exemplary embodiments, a first emitted light, a second emitted light, a third emitted light, and a fourth emitted light, modulated to different frequencies, may be simultaneously received. In this instance, a waveform of each of the four emitted lights is described in detail with reference to  FIG. 10 . 
     The light receiving unit  310  may be an IR sensor. However, the light receiving unit  310  may not be limited to the exemplary embodiment. Also, changes may be made with respect to the light receiving unit  310  depending on a type of signal emitted in a light emitting unit. 
     According to exemplary embodiments, a filtering unit  330  may analyze an amplitude for each frequency with respect to the first emitted light, the second emitted light, the third emitted light, and the fourth emitted light, when each of the four emitted lights is modulated to a first frequency, a second frequency, a third frequency, and a fourth frequency, and simultaneously emitted. 
     The filtering unit  330  may perform a band-pass filtering (BPF) with respect to the first emitted light received in the light receiving unit  310 , using the first frequency as a center frequency. Also, the filtering unit  330  may provide the filtered light to the calculation unit  320 . Also, the filtering unit  330  may filter the second emitted light according to the second frequency, the third emitted light according to the third frequency, and the fourth emitted light according to the fourth frequency. Here, the second emitted light, the third emitted light, and the fourth emitted light may be received in the light receiving unit  310 . 
     The BPF may be performed in parallel or sequentially. A quad configuration may be used to simultaneously filter the four frequencies. Four filters may be utilized in parallel, in the quad configuration. Those skilled in the art may change a configuration of filters without departing from the principles and spirit of the disclosure. 
     The calculation unit  320  may calculate a first coordinate axis value and a second coordinate axis value of a cursor on a display. The first coordinate axis value and the second coordinate axis value have been described in detail with reference to  FIG. 2 . 
     According to exemplary embodiments, when the first emitted light and the second emitted light are received during the first half cycle, the calculation unit  320  may calculate the first coordinate axis value, that is, an x coordinate value of the cursor. Also, when the third emitted light and the fourth emitted light are received during a second half cycle, the calculation unit  320  may calculate the second coordinate axis value, that is, a y coordinate value of the cursor. 
     In this instance, an operation of calculating the x coordinate value of the cursor based on amplitudes of the received emitted lights is described in detail with reference to  FIG. 5 ,  FIG. 7 , and  FIG. 9 . 
     According to other exemplary embodiments, when the four emitted lights are simultaneously emitted and received, the calculation unit  320  may simultaneously calculate the first coordinate axis value and the second coordinate axis value of the cursor. An operation of calculating the first coordinate axis value and the second coordinate axis value based on amplitudes of the received emitted lights is described in detail with reference to  FIG. 11 . 
       FIG. 4  is a diagram illustrating pulse trains of emitted lights according to exemplary embodiments. 
     According to exemplary embodiments, a signal illustrated in a graph  410  may be a first emitted light  412  emitted by the first light emitting unit  121  of  FIG. 1 . The first emitted light  412  may include a plurality of pulses and have a cycle T. Also, the first emitted light  412  may be emitted during a first half cycle  451 . 
     The first half cycle  451  may be a partial time period of the cycle T of the first emitted light  412 . The first half cycle  451  may be a period t (t 0 +k*T&lt;t&lt;t 1 +k*T). Here, k may be a positive number. Also, a second half cycle  461  may be a remaining time period of the cycle T. The second half cycle  461  may be another period t (t 1 +k*T&lt;t&lt; to +(k+1)T). Here, k may be a positive number. Hereinafter, the first half cycle  451  and the second half cycle  461  may be the same with respect to other emitted lights in  FIG. 4  through  FIG. 12 . 
     Although ‘first half cycle’ and ‘second half cycle’ are used for convenience of description, the cycle may not be limited to the exemplary embodiments. Accordingly, a time length of the first half cycle and the second half cycle are not required to be identical, and the time length may vary. 
     According to exemplary embodiments, a signal illustrated in a graph  420  may be a second emitted light  422  emitted by the second light emitting unit  122 . The second emitted light  422  may include a plurality of pulses and have the cycle T. Also, the second emitted light  422  may be emitted during the first half cycle  451 . 
     According to exemplary embodiments, a signal illustrated in a graph  430  may be a third emitted light  432  emitted by the third light emitting unit  123 . The third emitted light  432  may include a plurality of pulses and have the cycle T. Also, the third emitted light  432  may be emitted during the second half cycle  461 . 
     According to exemplary embodiments, a signal illustrated in a graph  440  may be a fourth emitted light  442  emitted by the fourth light emitting unit  124 . The fourth emitted light  442  may include a plurality of pulses and have the cycle T. Also, the fourth emitted light  442  may be emitted during the second half cycle  461 . 
     According to exemplary embodiments, the first light emitting unit  121 , the second light emitting unit  122 , the third light emitting unit  123 , and the fourth light emitting unit  124  may emit each control signal  411 ,  421 ,  431 , and  441  to distinguish the first half cycle  451  from the second half cycle  461 . Each of the control signals  411 ,  421 ,  431 , and  441  may be a periodic signal having the cycle T. 
     An amplitude of the first emitted light  412  is identical to an amplitude of the second emitted light  422 . Also, the first emitted light  412  and the second emitted light  422  have a first phase difference. According to exemplary embodiments, as illustrated in the graphs  410  and  420 , the first phase difference may be 180 degrees. However, the phase difference may not be limited to the exemplary embodiments, and be an arbitrary phase difference which prevents the first emitted light  412  and the second emitted light  422  from overlapping. 
     Also, an amplitude of the third emitted light  432  is identical to an amplitude of the fourth emitted light  442 . Also, the third emitted light  432  and the fourth emitted light  442  have a second phase difference. As illustrated in the graphs  430  and  440 , the second phase difference may be 180 degrees. According to other exemplary embodiments, however, the second phase difference may be an arbitrary phase difference which prevents the third emitted light  432  and the fourth emitted light  442  from overlapping. The first phase difference may be identical to the second phase difference. 
       FIG. 5  is a diagram illustrating waveforms when receiving the emitted lights of  FIG. 4 . 
     A graph  510  may illustrate emitted lights received during a first half cycle. Specifically, the emitted lights, that are received for a predetermined time (t 1 −t 0 ) after a control signal  511  is received, may be received during the first half cycle. Also, a light emitting unit emitting the emitted lights during the first half cycle may be the first light emitting unit  121  and the second light emitting unit  122 . 
     A received first emitted light  512  and second emitted light  513  may be used for calculating an x coordinate value, that is, a first coordinate axis value, of the cursor  230  of  FIG. 2 . An amplitude of the first emitted light  512  may be greater than an amplitude of the second emitted light  513  in the graph  510 . Although the first light emitting unit  121  and the second light emitting unit  122  emit emitted lights having a same amplitude, it may be sensed by the light receiving unit  240  that the amplitude of the first emitted light  512  is greater than the amplitude of the second emitted light  513 . Accordingly, it may be determined that a remote control  100 , that is, the apparatus  100 , that transmits emitted lights is towards a left side as opposed to a center. Accordingly, the x coordinate value of the cursor  230  may be a negative number, and be in proportion to a difference between the received first emitted light  512  and the second emitted light  513 . 
     A graph  520  may illustrate emitted lights received during the first half cycle. Specifically, the emitted lights, that are received for the predetermined time (t 1 −t 0 ) after a control signal  521  is received, may be received during the first half cycle. 
     A received first emitted light  522  and a second emitted light  523  may be used for calculating the x coordinate value, that is, the first coordinate axis value, of the cursor  230 . An amplitude of the first emitted light  522  may be the same as an amplitude of the second emitted light  523  in the graph  520 . Accordingly, it may not be determined that the remote control  100  that transmits emitted lights is towards the left or right. Accordingly, the x coordinate value of the cursor  230  may be 0. 
     A graph  530  may illustrate emitted lights received during the first half cycle. Specifically, the emitted lights, that are received for the predetermined time (t 1 −t 0 ) after a control signal  531  is received, may be received during the first half cycle. An amplitude of a first emitted light  532  may be less than an amplitude of a second emitted light  533  in the graph  530 . Accordingly, it may be determined that the remote control  100  that transmits emitted lights is towards the right. Accordingly, the x coordinate value of the cursor  230  may be a positive number, and be in proportion to a difference between the received first emitted light  532  and the second emitted light  533 . 
     A graph  540  may illustrate emitted lights received during a second half cycle. Specifically, the emitted lights, that are received for a predetermined time (t 0 +T−t 1 ) before a control signal  543  is received, may be received during the second half cycle. Also, a light emitting unit emitting the emitted lights during the second half cycle may be the third light emitting unit  123  and the fourth light emitting unit  124 . 
     A received third emitted light  541  and a fourth emitted light  542  may be used for calculating a y coordinate value, that is, a second coordinate axis value, of the cursor  230  of  FIG. 2 . An amplitude of the third emitted light  541  may be greater than an amplitude of the fourth emitted light  542  in the graph  540 . Although the third light emitting unit  123  and the fourth light emitting unit  124  emit emitted lights having a same amplitude, it may be sensed by the light receiving unit  240  that the amplitude of the third emitted light  541  is greater than the amplitude of the fourth emitted light  542 . Accordingly, it may be determined that the remote control  100  that transmits emitted lights is towards an upper part. Accordingly, the y coordinate value of the cursor  230  may be a positive number, and be in proportion to a difference between the received third emitted light  541  and fourth emitted light  542 . 
     A graph  550  may illustrate emitted lights received during the second half cycle. Specifically, the emitted lights, that are received for the predetermined time (t 0 +T−t 1 ) before a control signal  553  is received, may be received during the second half cycle. 
     A received third emitted light  551  and fourth emitted light  552  may be used for calculating the y coordinate value, that is, second coordinate axis value, of the cursor  230 . An amplitude of the third emitted light  551  may be the same as an amplitude of fourth emitted light  552  in the graph  550 . Accordingly, it may not be determined that the remote control  100  that transmits emitted lights is towards an upper or lower part. Accordingly, the y coordinate value of the cursor  230  may be 0. 
     A graph  560  may illustrate emitted lights received during the second half cycle. Specifically, the emitted lights, that are received for a predetermined time (t 0 +T−t 1 ) before a control signal  563  is received, may be received during the second half cycle. An amplitude of a third emitted light  561  may be less than an amplitude of a fourth emitted light  562  in the graph  560 . Accordingly, it may be determined that the remote control  100  that transmits emitted lights is towards a lower part. Accordingly, the y coordinate value of the cursor  230  may be a negative number, and be in proportion to a difference between the received third emitted light  561  and fourth emitted light  562 . 
       FIG. 6  is a diagram illustrating sawtooth waveforms of emitted lights, which are continuous signals, according to exemplary embodiments. 
     According to exemplary embodiments, a signal illustrated in a graph  610  may be a first emitted light  612  emitted by the first light emitting unit  121  of  FIG. 1 . The first emitted light  612  may be a signal of a downward ramp sawtooth waveform, and a continuous signal. The first emitted light  612  may have a cycle T, and be emitted during a first half cycle. 
     According to exemplary embodiments, a signal illustrated in a graph  620  may be a second emitted light  622  emitted by the second light emitting unit  122  of  FIG. 1 . The second emitted light  622  may be a signal of an upward ramp sawtooth waveform, and a continuous signal. The second emitted light  622  may have the cycle T, and be emitted during the first half cycle. 
     According to exemplary embodiments, a signal illustrated in a graph  630  may be a third emitted light  632  emitted by the third light emitting unit  123  of  FIG. 1 . The third emitted light  632  may be a signal of a downward ramp sawtooth waveform, and a continuous signal. The third emitted light  632  may have the cycle T, and be emitted during a second half cycle. 
     According to exemplary embodiments, a signal illustrated in a graph  640  may be a fourth emitted light  642  emitted by the fourth light emitting unit  124  of  FIG. 1 . The fourth emitted light  642  may be a signal of an upward ramp sawtooth waveform, and a continuous signal. The fourth emitted light  642  may have the cycle T, and be emitted during the second half cycle. 
     According to exemplary embodiments, the first light emitting unit  121 , the second light emitting unit  122 , the third light emitting unit  123 , and the fourth light emitting unit  124  may emit each control signal  611 ,  621 ,  631 , and  641  to distinguish the first half cycle from the second half cycle. Each of the control signals  611 ,  621 ,  631 , and  641  may be a periodic signal having the cycle T. 
     The first emitted light  612  and the second emitted light  622  may have a same maximum amplitude. The third emitted light  632  and the fourth emitted light  642  may have a same maximum amplitude. 
       FIG. 7  is a diagram illustrating waveforms when receiving the emitted lights of  FIG. 6 . 
     A graph  710  may illustrate an emitted light received during a first half cycle. Specifically, the emitted light, that is received for a predetermined time (t 1 −t 0 ) after a control signal  711  is received, may be received during the first half cycle. Also, a light emitting unit emitting the emitted light during the first half cycle may be the first light emitting unit  121  and the second light emitting unit  122 . 
     A received emitted light  712  is used for calculating an x coordinate value, that is, a first coordinate axis value, of the cursor  230  of  FIG. 2 . An amplitude of the emitted light  712  may show a ramp-down characteristic in the graph  710 . Although the first light emitting unit  121  and the second light emitting unit  122  emit emitted lights of the downward ramp sawtooth waveform and the upward ramp sawtooth waveform, the ramp-down characteristic may be sensed by the light receiving unit  240 . In this instance, the emitted lights of the downward ramp sawtooth waveform and the upward ramp sawtooth waveform may have a same maximum amplitude. Accordingly, it may be determined that a remote control  100  that transmits emitted lights is towards a left side. Accordingly, the x coordinate value of the cursor  230  may be a negative number, and be in proportion to a difference between a maximum amplitude and a minimum amplitude of the received emitted light  712 . 
     A graph  720  may illustrate an emitted light received during the first half cycle. Specifically, the emitted light, that is received for the predetermined time (t 1 −t 1 ) after a control signal  721  is received, may be received during the first half cycle. 
     A received emitted light  722  is used for calculating the x coordinate value, that is, the first coordinate axis value, of the cursor  230 . The received emitted light  722  may show a characteristic of a constant amplitude in the graph  720 . Accordingly, it may not be determined that the remote control  100  that transmits emitted lights is towards the left or right. Accordingly, the x coordinate value of the cursor  230  may be 0. 
     A graph  730  may illustrate an emitted light received during the first half cycle. Specifically, the, emitted light, that is received for the predetermined time (t 1 −t 0 ) after a control signal  731  is received, may be received during the first half cycle. An amplitude of a received emitted light  732  may show a ramp-up characteristic in the graph  730 . Accordingly, it may be determined that the remote control  100  that transmits emitted lights is towards the right. Accordingly, the x coordinate value of the cursor  230  may be a positive number, and be in proportion to a difference between a maximum amplitude and a minimum amplitude of the received emitted light  732 . 
     A graph  740  may illustrate an emitted light received during a second half cycle. Specifically, the emitted light, that is received for a predetermined time (t 0 +T−t 1 ) before a control signal  742  is received, may be received during the second half cycle. Also, a light emitting unit emitting the emitted lights during the second half cycle may be the third light emitting unit  123  and the fourth light emitting unit  124 . 
     A received emitted light  741  is used for calculating a y coordinate value, that is, a second coordinate axis value, of the cursor  230 . An amplitude of the emitted light  741  may show a ramp-down characteristic in the graph  740 . Although the third light emitting unit  123  and the fourth light emitting unit  124  emit emitted lights having a same amplitude, the ramp-down characteristic may be sensed by the light receiving unit  240 . Accordingly, it may be determined that the remote control  100  that transmits emitted lights is towards an upper part. Accordingly, the y coordinate value of the cursor  230  may be a positive number, and be in proportion to a difference between a maximum amplitude and a minimum amplitude of the emitted light  742 . 
     A graph  750  may illustrate an emitted light received during the second half cycle. Specifically, the emitted light, that is received for the predetermined time (t 0 +T−t 1 ) before the control signal  752  is received, may be received during the second half cycle. 
     A received emitted light  751  may show a constant amplitude characteristic in the graph  750 . Accordingly, it may not be determined that the remote control  100  that transmits emitted lights is towards the upper or the lower part. Accordingly, the y coordinate value of the cursor  230  may be 0. 
     A graph  760  may illustrate an emitted light received during the second half cycle. Specifically, the emitted light, that is received for the predetermined time (t 0 +T−t 1 ) before a control signal  762  is received, may be received during the second half cycle. An amplitude of a received emitted light  761  may show a ramp-up characteristic in the graph  760 . Accordingly, it may be determined that the remote control  100  that transmits emitted lights is towards a lower part. Accordingly, the y coordinate value of the cursor  230  may be a negative number, and be in proportion to a difference between a maximum amplitude and a minimum amplitude of the emitted light  761 . 
       FIG. 8  is a diagram illustrating emitted ramp signal lights according to exemplary embodiments. 
     According to exemplary embodiments, a signal illustrated in a graph  810  may be a first emitted light  812  emitted by the first light emitting unit  121  of  FIG. 1 . The first emitted light  812  may be a downward ramp pulse train signal having a ramp-down characteristic. The first emitted light  812  may have a cycle T, and be emitted during a first half cycle. 
     According to exemplary embodiments, a signal illustrated in a graph  820  may be a second emitted light  822  emitted by the second light emitting unit  122  of  FIG. 1 . The second emitted light  822  may be an upward ramp pulse train signal having a ramp-up characteristic. The second emitted light  822  may have the cycle T, and be emitted during the first half cycle. 
     According to exemplary embodiments, a signal illustrated in a graph  830  may be a third emitted light  832  emitted by the third light emitting unit  123  of  FIG. 1 . The third emitted light  832  may be a downward ramp pulse train signal having a ramp-down characteristic. The third emitted light  832  may have the cycle T, and be emitted during a second half cycle. 
     According to exemplary embodiments, a signal illustrated in a graph  840  may be a fourth emitted light  842  emitted by the fourth light emitting unit  124  of  FIG. 1 . The fourth emitted light  842  may be an upward ramp pulse train signal having a ramp-up characteristic. The fourth emitted light  842  may have the cycle T, and be emitted during the second half cycle. 
     According to exemplary embodiments, the first light emitting unit  121 , the second light emitting unit  122 , the third light emitting unit  123 , and the fourth light emitting unit  124  may emit each control signal  811 ,  821 ,  831 , and  841  to distinguish the first half cycle from the second half cycle. Each of the control signals  811 ,  821 ,  831 , and  841  may be a periodic signal having the cycle T. 
     The first emitted light  812  and the second emitted light  822  may have a same maximum amplitude. The third emitted light  832  and the fourth emitted light  842  may have a same maximum amplitude. 
     According to exemplary embodiments, the first emitted light  812  may be a pulse train showing the ramp-down characteristic at least twice during the first half cycle. In this instance, the second emitted light  822  may be a pulse train showing the ramp-up characteristic a same number of times as the number of times that the ramp-down characteristic shows in the first emitted light  812 . Similarly, the third emitted light  832  may be a pulse train showing the ramp-down characteristic at least twice during the first half cycle. In this instance, the fourth emitted light  842  may be a pulse train showing the ramp-up characteristic a same number of times as the number of times that the ramp-down characteristic shows in the third emitted light  832 . 
     For example, each of the first emitted light  812  and the third emitted light  832  may ramp downward three times, and each of the second emitted light  822  and the fourth emitted light  842  may ramp upwards three times. In this instance, each of the first emitted light  812 , the second emitted light  822 , the third emitted light  832 , and the fourth emitted light  842  may be a pulse train signal converted from the first emitted light  612 , the second emitted light  622 , the third emitted light  632 , and the fourth emitted light  642  of  FIG. 6 . Here, each of the first emitted light  812 , the second emitted light  822 , the third emitted light  832 , and the fourth emitted light  842  may be a continuous signal, and the pulse train signal may be a discrete signal. 
       FIG. 9  is a diagram illustrating waveforms when receiving the emitted lights of  FIG. 8 . 
     According to exemplary embodiments, the light receiving unit  310  of  FIG. 3  may receive the first emitted light  812  and the second emitted light  822  during the first half cycle, and compare amplitudes of the first emitted light  812  and the second emitted light  822 . Also, the light receiving unit  310  may receive the third emitted light  832  and the fourth emitted light  842  during the second half cycle, and compare amplitudes of the third emitted light  832  and the fourth emitted light  842 . 
     A graph  910  may illustrate emitted lights received during a first half cycle. Specifically, the emitted lights, that are received for a predetermined time (t 1 −t 0 ) after a control signal  911  is received, may be received during the first half cycle. Also, a light emitting unit emitting the emitted light during the first half cycle may be the first light emitting unit  121  and the second light emitting unit  122 . 
     A received first emitted light  912  and second emitted light  913  may be used for calculating an x coordinate value, that is, a first coordinate axis value, of the cursor  230  of  FIG. 2 . An amplitude of the first emitted light  912  and an amplitude of the second emitted light  913  may be identical at t 2 +α in the graph  910 . Although the first light emitting unit  121  and the second light emitting unit  122  emit the emitted lights having a same maximum amplitude, it may be sensed by the light receiving unit  240  that a time that the amplitude of the first emitted light  912  is identical to the amplitude of the second emitted light  913  is close to t 1 . Here, the emitted lights having the same maximum amplitude may be signals of a ramp downward pulse train and a ramp upward pulse train. Accordingly, it may be determined that a remote control  100  that transmits emitted lights is towards the left. Thus, the x coordinate value of the cursor  230  may be a negative number, and be in proportion to a indicating how close the time and t 1  are. 
     A graph  920  may illustrate emitted lights received during the first half cycle. Specifically, the emitted lights, that are received for the predetermined time (t 1 −t 0 ) after a control signal  921  is received, may be received during the first half cycle. 
     A received first emitted light  922  and second emitted light  923  may be used for calculating the x coordinate value, that is, the first coordinate axis value, of the cursor  230 . Since an amplitude of the first emitted light  922  and an amplitude of the second emitted light  923  may be identical at t 2  in the graph  920 , the first emitted light  922  and second emitted light  923  may be balanced. Accordingly, it may not be determined that the remote control  100  that transmits emitted lights is towards the left or right. Accordingly, the x coordinate value of the cursor  230  may be 0. 
     A graph  930  may illustrate emitted lights received during the first half cycle. Specifically, the emitted lights, that are received for the predetermined time (t 1 −t 0 ) after a control signal  931  is received, may be received during the first half cycle. An amplitude of the first emitted light  932  and an amplitude of the second emitted light  933  may be identical at t 2 −α in the graph  930 . Although the first light emitting unit  121  and the second light emitting unit  122  emit the emitted lights having a same maximum amplitude, it may be sensed by the light receiving unit  240  that a time that the amplitude of the first emitted light  932  is identical to the amplitude of the second emitted light  933  is close to t 0 . Here, the emitted lights having the same maximum amplitude may be signals of a ramp downward pulse train and a ramp upward pulse train. Accordingly, it may be determined that the remote control  100  that transmits emitted lights is towards the right. Thus, the x coordinate value of the cursor  230  may be a positive number, and be in proportion to α. 
     A graph  940  may illustrate emitted lights received during the second half cycle. Specifically, the emitted lights, that are received for a predetermined time (t 0 +T−t 1 ) before a control signal  943  is received, may be received during the second half cycle. Also, a light emitting unit emitting the emitted lights during the second half cycle may be the third light emitting unit  123  and the fourth light emitting unit  124 . 
     A received third emitted light  941  and fourth emitted light  942  may be used for calculating a y coordinate value, that is, a second coordinate axis value, of the cursor  230 . An amplitude of the first emitted light  941  and an amplitude of the second emitted light  942  may be identical at t 2 +α in the graph  940 . Although the third light emitting unit  123  and the fourth light emitting unit  124  emit the emitted lights having a same maximum amplitude, it may be sensed by the light receiving unit  240  that a time that the amplitude of the first emitted light  941  is identical to the amplitude of the second emitted light  942  is close to t 0 +T. Here, the emitted lights having the same maximum amplitude may be signals of a ramp downward pulse train and a ramp upward pulse train. Accordingly, it may be determined that the remote control  100  that transmits emitted lights is towards an upper part. Thus, the x coordinate value of the cursor  230  may be a positive number, and be in proportion to α. 
     A graph  950  may illustrate emitted lights received during the second half cycle. Specifically, the emitted lights, that are received for the predetermined time (t 0 +T−t 1 ) before a control signal  953  is received, may be received during the second half cycle. 
     A received third emitted light  951  and a received fourth emitted light  952  may be used for calculating the y coordinate value, that is, second coordinate axis value, of the cursor  230 . Since an amplitude of the first emitted light  951  and an amplitude of the second emitted light  952  may be identical at t 2  in the graph  950 , the first emitted light  951  and second emitted light  952  may be balanced. Accordingly, it may not be determined that the remote control  100  that transmits emitted lights is towards an upper or a lower part. Accordingly, the y coordinate value of the cursor  230  may be 0. 
     A graph  960  may illustrate emitted lights received during the second half cycle. Specifically, the emitted lights, that are received for a predetermined time (t 0 +T−t 1 ) before a control signal  963  is received, may be received during the second half cycle. An amplitude of a first emitted light  961  and an amplitude of a second emitted light  962  may be identical at t 2 −α in the graph  960 . Although the third light emitting unit  123  and the fourth light emitting unit  124  emit the emitted lights having a same maximum amplitude, it may be sensed by the light receiving unit  240  that a time that the amplitude of the first emitted light  961  is identical to the amplitude of the second emitted light  962  is close to t 1 . Here, the emitted lights having the same maximum amplitude may be signals of a ramp downward pulse train and a ramp upward pulse train. Accordingly, it may be determined that the remote control  100  that transmits emitted lights is towards a lower part. Thus, the y coordinate value of the cursor  230  may be a negative number, and be in proportion to α. 
       FIG. 10  is a diagram illustrating emitted frequency-modulated lights according to exemplary embodiments. 
     According to exemplary embodiments, a control signal is not required. 
     A first emitted light  1010  may be modulated to a first frequency and emitted by the first light emitting unit  121 . A second emitted light  1020  may be modulated to a second frequency and emitted by the second light emitting unit  122 . A third emitted light  1030  may be modulated to a third frequency and emitted by the third light emitting unit  123 , and a fourth emitted light  1040  may be modulated to a fourth frequency and emitted by the fourth light emitting unit  124 . 
     According to exemplary embodiments, an amplitude of the first emitted light  1010  is identical to an amplitude of the second emitted light  1020 . Also, an amplitude of the third emitted light  1030  is identical to an amplitude of the fourth emitted light  1040 . 
       FIG. 11  is a diagram illustrating waveforms when receiving the emitted lights of  FIG. 10 . 
     The light receiving unit  310  may receive waves where the first emitted light  1010 , the second emitted light  1020 , the third emitted light  1030 , and the fourth emitted light  1040  overlap. Also, the filtering unit  330  may filter the received first emitted light  1010 , the received second emitted light  1020 , the received third emitted light  1030 , and the received fourth emitted light  1040  to a first frequency component, a second frequency component, a third frequency component, and a fourth frequency component; 
     The calculation unit  320  may compare amplitudes of the first frequency component and the second frequency component, and calculate an x coordinate value, that is, a first coordinate axis value, of the cursor  230 . Also, the calculation unit  320  may compare amplitudes of the third frequency component and the fourth frequency component, and calculate a y coordinate value, that is, a second coordinate axis value, of the cursor  230 . Since the calculating of the x coordinate value and the y coordinate value may be simultaneously performed, calculation may be quickly performed. 
     A graph  1110  may illustrate a filtered first frequency component  1111  and second frequency component  1112 . The first frequency component  1111  and second frequency component  1112  may be used for calculating the x coordinate value, that is, the first coordinate axis value, of the cursor  230 . An amplitude of the first frequency component  1111  may be greater than an amplitude of the second frequency component  1112  in the graph  1110 . Although the first light emitting unit  121  and the second light emitting unit  122  emit emitted lights having a same amplitude, it may be sensed by the light receiving unit  240  that the amplitude of the first frequency component  1111  is greater than the amplitude of the second frequency component  1112 . Accordingly, it may be determined that a remote control  100  that transmits emitted lights is towards the left. Accordingly, the x coordinate value of the cursor  230  may be a negative number, and may be in proportion to a difference between the amplitudes of the first frequency component  1111  and the second frequency component  1112 . 
     A graph  1120  may illustrate a filtered first frequency component  1121  and second frequency component  1122 . The first frequency component  1121  and second frequency component  1122  may be used for calculating the x coordinate value, that is, the first coordinate axis value, of the cursor  230 . An amplitude of the first frequency component  1121  may be identical to an amplitude of the second frequency component  1122  in the graph  1120 . Accordingly, it may not be determined that the remote control  100  that transmits emitted lights is towards the left or right. Accordingly, the x coordinate value of the cursor  230  may be 0. 
     A graph  1130  may illustrate a filtered first frequency component  1131  and second frequency component  1132 . The first frequency component  1131  and second frequency component  1132  may be used for calculating the x coordinate value, that is, the first coordinate axis value, of the cursor  230 . An amplitude of the first frequency component  1131  may be less than an amplitude of the second frequency component  1132  in the graph  1130 . Although the first light emitting unit  121  and the second light emitting unit  122  emit emitted lights having a same amplitude, it may be sensed by the light receiving unit  240  that the amplitude of the first frequency component  1131  is less than the amplitude of the second frequency component  1132 . Accordingly, it may be determined that the remote control  100  that transmits emitted lights is towards the right. Accordingly, the x coordinate value of the cursor  230  may be a positive number, and be in proportion to a difference between the amplitudes of the first frequency component  1131  and the second frequency component  1132 . 
     A graph  1140  may illustrate a filtered third frequency component  1141  and a filtered fourth frequency component  1142 . The third frequency component  1141  and the fourth frequency component  1142  may be used for calculating the y coordinate value, that is, the second coordinate axis value, of the cursor  230 . An amplitude of the third frequency component  1141  may be greater than an amplitude of the fourth frequency component  1142  in the graph  1140 . Although the third light emitting unit  123  and the fourth light emitting unit  124  emit emitted lights having a same amplitude, it may be sensed by the light receiving unit  240  that the amplitude of the third frequency component  1141  is greater than the amplitude of the fourth frequency component  1142 . Accordingly, it may be determined that the remote control  100  that transmits emitted lights is towards an upper part. Accordingly, the y coordinate value of the cursor  230  may be a positive number, and be in proportion to a difference between the amplitudes of the third frequency component  1141  and the fourth frequency component  1142 . 
     A graph  1150  may illustrate a filtered third frequency component  1151  and a filtered fourth frequency component  1152 . The third frequency component  1151  and the fourth frequency component  1152  may be used for calculating the y coordinate value, that is, the second coordinate axis value, of the cursor  230 . An amplitude of the third frequency component  1151  may be identical to an amplitude of the fourth frequency component  1152  in the graph  1150 . Accordingly, it may not be determined that the remote control  100  that transmits emitted lights faces upwards or downwards. Accordingly, the y coordinate value of the cursor  230  may be 0. 
     A graph  1160  may illustrate a filtered third frequency component  1161  and a filtered fourth frequency component  1162 . The third frequency component  1161  and the fourth frequency component  1162  may be used for calculating the y coordinate value, that is, the second coordinate axis value, of the cursor  230 . An amplitude of the third frequency component  1161  may be less than an amplitude of the fourth frequency component  1162  in the graph  1160 . Although the third light emitting unit  123  and the fourth light emitting unit  124  emit emitted lights having a same amplitude, it may be sensed by the light receiving unit  240  that the amplitude of the third frequency component  1161  is less than the amplitude of the fourth frequency component  1162 . Accordingly, it may be determined that the remote control  100  that transmits emitted lights is towards a lower part. Accordingly, the y coordinate value of the cursor  230  may be a negative number, and may be in proportion to a difference between the amplitudes of the third frequency component  1161  and the fourth frequency component  1162 . 
       FIG. 12  is a flowchart illustrating a remote pointing method according to exemplary embodiments. 
     In operation S 1210 , a first emitted light, a second emitted light, a third emitted light, and a fourth emitted light may be emitted. Each of the first emitted light, the second emitted light, the third emitted light, and the fourth emitted light may be emitted in a first light emitting unit  121 , a second light emitting unit  122 , a third light emitting unit  123 , and a fourth light emitting unit  124 , respectively. 
     According to exemplary embodiments, the first emitted light and the second emitted light may be emitted during a first half cycle, and the third emitted light and the fourth emitted light may be emitted during a second half cycle. In this instance, a waveform of each of the four emitted lights is illustrated in  FIGS. 4 ,  6 , and  8 . However, the waveform may not be limited to the exemplary embodiments. Specifically, as long as an x coordinate value, that is, a first coordinate axis value, of the cursor  230  may be determined by comparing amplitudes of the first emitted light and the second emitted light, and as long as a y coordinate value, that is, a second coordinate axis value, of the cursor  230  may be determined by comparing amplitudes of the third emitted light and the fourth emitted light, changes may be made with respect to the waveform of each of the four emitted lights. 
     Also, in operation S 1210 , the four emitted lights which are periodic waves may be emitted together with each control signal in the first light emitting unit  121 , the second light emitting unit  122 , the third light emitting unit  123 , and the fourth light emitting unit  124 . 
     According to other exemplary embodiments, the first emitted light, the second emitted light, the third emitted light, and the fourth emitted light may be modulated to a first frequency, a second frequency, a third frequency, and a fourth frequency, respectively, and simultaneously emitted. In this instance, the control signal is not required to be transmitted. Also, an amplitude of the first emitted light is required to be identical to an amplitude of the second emitted light, and an amplitude of the third emitted light is required to be identical to an amplitude of the fourth emitted light. 
     In operation S 1220 , the light receiving unit  310  may receive the first emitted light, the second emitted light, the third emitted light, and the fourth emitted light. According to exemplary embodiments, the light receiving unit  310  may be an IR sensor. However, the light receiving unit  310  may vary depending on a type of a signal transmitted in a light emitting unit. 
     In operation S 1230 , according to other exemplary embodiments, when the first emitted light, the second emitted light, the third emitted light, and the fourth emitted light are modulated to the first frequency, the second frequency, the third frequency, and the fourth frequency, respectively, and simultaneously emitted, the filtering unit  330  may perform a BPF with respect to the first emitted light received in the light receiving unit  310 , using the first frequency as a center frequency. Also, the filtering unit  330  may provide the filtered light to the calculation unit  320 . Also, the filtering unit  330  may filter the second emitted light to the second frequency, the third emitted light to the third frequency, and the fourth emitted light to the fourth frequency. Here, the second emitted light, the third emitted light, and the fourth emitted light may be received in the light receiving unit  310 . 
     The BPF may be performed in parallel or sequentially. A quad configuration may be used to simultaneously filter the four frequencies. Four filters may be performed in parallel, in the quad configuration. Those skilled in the art may change a configuration of filter without departing from the principles and spirit of the disclosure. 
     In operation S 1240 , a first coordinate axis value and a second coordinate axis value of the cursor  230  on a display may be calculated. 
     According to exemplary embodiments, when the first emitted light and the second emitted light are received during a first half cycle, the calculation unit  320  may calculate the first coordinate axis value, that is, an x coordinate value of the cursor  230 . Also, when the third emitted light and the fourth emitted light are received during a second half cycle, the calculation unit  320  may calculate the second coordinate axis value, that is, a y coordinate value of the cursor  230 . 
     In this instance, an operation of calculating the x coordinate value of the cursor based on amplitudes of the received emitted lights has been described in detail with reference to  FIG. 5 ,  FIG. 7 , and  FIG. 9 . 
     According to other exemplary embodiments, when the four emitted lights are simultaneously emitted and received, the calculation unit  320  may simultaneously calculate the first coordinate axis value and the second coordinate axis value of the cursor  230 . An operation of calculating the first coordinate axis value and the second coordinate axis value based on amplitudes of the received emitted lights has been described in detail with reference to  FIG. 11 . 
     The remote pointing method according to the above-described exemplary embodiments may be recorded in computer-readable media including program instructions to implement various operations embodied by a computer. The media may also include, alone or in combination with the program instructions, data files, data structures, and the like. Examples of computer-readable media include magnetic media such as hard disks, floppy disks, and magnetic tape; optical media such as CD ROM disks and DVDs; magneto-optical media such as optical disks; and hardware devices that are specially configured to store and perform program instructions, such as read-only memory (ROM), random access memory (RAM), flash memory, and the like. The computer-readable media may also be a distributed network, so that the program instructions are stored and executed in a distributed fashion. The program instructions may be executed by one or more processors. The computer-readable media may also be embodied in at least one application specific integrated circuit (ASIC) or Field Programmable Gate Array (FPGA). Examples of program instructions include both machine code, such as produced by a compiler, and files containing higher level code that may be executed by the computer using an interpreter. The described hardware devices may be configured to act as one or more software modules in order to perform the operations of the above-described exemplary embodiments, or vice versa. 
     Although a few exemplary embodiments have been shown and described, the present disclosure is not limited to the described exemplary embodiments. Instead, it would be appreciated by those skilled in the art that changes may be made to these exemplary embodiments without departing from the principles and spirit of the disclosure, the scope of which is defined by the claims and their equivalents.