Patent Publication Number: US-2015063068-A1

Title: Sensing device and positioning method

Description:
RELATED APPLICATIONS 
     This application claims priority to Taiwan Application Serial Number 102130854, filed Aug. 28, 2013, which is herein incorporated by reference. 
     BACKGROUND 
     1. Field of Invention 
     The present invention relates to a sensing device. More particularly, the present invention relates to a sensing device and a positioning method to perform detection using sonic waves. 
     2. Description of Related Art 
     With the progress of display and touch technologies, user-friendly interfaces enabling the communications between electronic systems and users have been extensively applied in different fields, such as cell phones, display panels, tutoring systems, etc. An ultrasonic touch system is a common application of touch technology. The ultrasonic touch system detects the position of an object and generating an instruction corresponding to the position based on the reflected wave generated by the object being detected and intensity of the reflected wave. 
     Several sensing methods have been developed in the ultrasonic touch systems used in some approaches. One type of ultrasonic touch system includes an ultrasonic transmitter and ultrasonic sensors positioned around the object to be detected. The ultrasonic transmitter transmits a sonic signal to the object to be detected, and the ultrasonic sensors are configured for receiving the sonic signals reflected from the object, so as to calculate and position the relative position of the object. However, in this application, the configuration of positions of the ultrasonic sensors is strictly limited to ensure that each of the ultrasonic sensors is able to receive a single reflected sonic signal. In addition, when there is an excessive number of ultrasonic sensors, the computational complexity of the overall system is too high so that time delays in subsequent executions are caused. 
     Another type of ultrasonic touch system comprises a plurality of ultrasonic transceivers positioned around the object to be detected. The ultrasonic transceivers are configured for respectively generating sonic signals at the same time so as to monitor the object within a predetermined distance. However, in this system, the system cannot perform the subsequent calculations for positioning unless each of the ultrasonic transceivers has received the individual sonic signal reflected from the object to be detected within the above-mentioned predetermined distance. The positioning update rate of the system is thus not sufficient so that a real-time calculation cannot be provided for the current touch operation. 
     For the forgoing reasons, there is a need for effectively improving the detection update rate and calculating the position of the object to be detected more efficiently using an ultrasonic wave to perform touch control, which is also the object that the industry eagers to achieve. 
     SUMMARY 
     One aspect of the present disclosure is to provide a sensing device. The sensing device is configured to mount around a display module to detect an object. The display module has a display screen for displaying an image. The sensing device includes a first sonic wave transceiver, a second sonic wave transceiver and a control module. The first sonic wave transceiver is configured for transmitting a first sonic wave. The second sonic wave transceiver is configured for transmitting a second sonic wave. The first sonic wave transceiver and the second sonic wave transceiver are further configured for receiving a first reflected sonic wave and a second reflected sonic wave generated in accordance with the first sonic wave and the second sonic wave, respectively. A frequency of the first sonic wave and the second sonic wave is between 50 KHz and 70 KHz. The control module is electrically coupled to the first sonic wave transceiver and the second sonic wave transceiver, and the control module is configured for controlling the first sonic wave transceiver and the second sonic wave transceiver. The control module further calculates a position of the object relative to the display module in accordance with the first reflected sonic wave and a second reflected sonic wave. By setting the frequency of the first sonic wave and the second sonic wave between 50 KHz and 70 KHz, the first sonic wave transceiver and the second sonic wave transceiver are allowed to receive the first reflected sonic wave and the second reflected sonic wave more accurately. 
     According to a first embodiment of the present disclosure, the control module is further configured for controlling the first sonic wave transceiver to transmit the first sonic wave, and controlling the second sonic wave transceiver to transmit the second sonic wave or controlling the first sonic wave transceiver to transmit the first sonic wave again in accordance with whether the first sonic wave transceiver receives the first reflected sonic wave. A transmission path of the first sonic wave at least partially overlaps a transmission path of the second sonic wave. 
     According to a first embodiment of the present disclosure, the first sonic wave includes a vertical beam angle in a vertical direction perpendicular to the display screen. The vertical beam angle is from 15 to 40 degrees. 
     According to a first embodiment of the present disclosure, the first sonic wave includes a horizontal beam angle in a horizontal direction parallel with the display screen. The horizontal beam angle is from 80 to 100 degrees. 
     According to a first embodiment of the present disclosure, the first sonic wave transceiver has a transmitting terminal configured for generating the first sonic wave. The first sonic wave transceiver further include a sound absorbing material extending from the transmitting terminal and elongated along a propagation direction of the first sonic wave. 
     According to a first embodiment of the present disclosure, the control module is further configured for monitoring whether an intensity of the first reflected sonic wave is greater than or equal to a threshold value. When the intensity of the first reflected sonic wave is greater than or equal to the threshold value, the control module interrupts monitoring of the intensity of the first reflected sonic wave, and calculates a distance of the object relative to the first sonic wave transceiver in accordance with a time at which the intensity of the first reflected sonic wave is greater than or equal to the threshold value and a time at which the first sonic wave is transmitted. 
     Another aspect of the present disclosure is to provide a sensing device. The sensing device is configured to mount around a display module to detect an object. The display module has a display screen for displaying an image. The sensing device includes a first sonic wave transceiver, a second sonic wave transceiver, and a control module. The first sonic wave transceiver is configured for transmitting a first sonic wave. The second sonic wave transceiver is configured for transmitting a second sonic wave. The first sonic wave transceiver and the second sonic wave transceiver are further configured for receiving a first reflected sonic wave and a second reflected sonic wave generated based on the first sonic wave and the second sonic wave, respectively. The first sonic wave includes a vertical beam angle in a vertical direction perpendicular to the display screen. The vertical beam angle is from 15 to 40 degrees. The control module is electrically coupled to the first sonic wave transceiver and the second sonic wave transceiver, and the control module is configured for controlling the first sonic wave transceiver and the second sonic wave transceiver. The control module further calculates a position of the object relative to the display module based on the above first reflected sonic wave and a second reflected sonic wave. By setting the above vertical beam angle, the present embodiment sensing device is allowed to have a more accurate detection distance to avoid misjudgments. 
     According to a second embodiment of the present disclosure, the first sonic wave includes a horizontal beam angle in a horizontal direction parallel with the display screen. The horizontal beam angle is from 80 to 100 degrees. 
     According to a second embodiment of the present disclosure, the control module is further configured for controlling the first sonic wave transceiver to transmit the first sonic wave, and controlling the second sonic wave transceiver to transmit the second sonic wave or controlling the first sonic wave transceiver to transmit the first sonic wave again depending on whether the first sonic wave transceiver receives the first reflected sonic wave. A transmission path of the first sonic wave at least partially overlaps a transmission path of the second sonic wave. 
     According to a second embodiment of the present disclosure, the control module is further configured for monitoring whether an intensity of the first reflected sonic wave is greater than or equal to a threshold value. When the intensity of the first reflected sonic wave is greater than or equal to the threshold value, the control module interrupts monitoring of the intensity of the first reflected sonic wave, and calculates a distance of the object relative to the first sonic wave transceiver in accordance with a time at which the intensity of the first reflected sonic wave is greater than or equal to the threshold value and a time at which the first sonic wave is transmitted. 
     According to a second embodiment of the present disclosure, the first sonic wave transceiver has a transmitting terminal configured for generating the first sonic wave. The first sonic wave transceiver further includes a sound absorbing material extending from the transmitting terminal and elongated along a propagation direction of the first sonic wave. 
     Yet one aspect of the present disclosure further provides a sensing device. The sensing device is configured to mount around a display module to detect an object. The display module includes a display screen for displaying an image. The sensing device comprises a first sonic wave transceiver, a second sonic wave transceiver, and a control module. The first sonic wave transceiver is configured for transmitting a first sonic wave. The second sonic wave transceiver is configured for transmitting a second sonic wave. The first sonic wave transceiver and the second sonic wave transceiver are further configured for receiving a first reflected sonic wave and a second reflected sonic wave generated in accordance with the first sonic wave and the second sonic wave, respectively. The control module is electrically coupled to the first sonic wave transceiver and the second sonic wave transceiver, and the control module is configured for controlling the first sonic wave transceiver and the second sonic wave transceiver. The control module further calculates a position of the object relative to the display module in accordance with the above first reflected sonic wave and a second reflected sonic wave. The control module is further configured for controlling the first sonic wave transceiver to transmit the first sonic wave, and controlling the second sonic wave transceiver to transmit the second sonic wave or controlling the first sonic wave transceiver to transmit the first sonic wave again selectively depending on whether the first sonic wave transceiver receives the first reflected sonic wave. A transmission path of the first sonic wave at least partially overlaps a transmission path of the second sonic wave. The sensing device in the present embodiment can avoid the second sonic transceiver to transmit the second sonic wave redundantly. 
     According to a third embodiment of the present disclosure, the control module is further configured for monitoring whether an intensity of the first reflected sonic wave is greater than or equal to a threshold value. When the intensity of the first reflected sonic wave is greater than or equal to the threshold value, the control module interrupts monitoring of the intensity of the first reflected sonic wave, and calculates a distance of the object relative to the first sonic wave transceiver in accordance with a time at which the intensity of the first reflected sonic wave is greater than or equal to the threshold value and a time at which the first sonic wave is transmitted. 
     According to a third embodiment of the present disclosure, the first sonic wave includes a vertical beam angle in a vertical direction perpendicular to the display screen. The vertical beam angle is from 15 to 40 degrees. 
     According to a third embodiment of the present disclosure, the first sonic wave includes a horizontal beam angle in a horizontal direction parallel with the display screen. The horizontal beam angle is from 80 to 100 degrees. 
     According to a third embodiment of the present disclosure, the first sonic wave transceiver has a transmitting terminal configured for generating the first sonic wave. The first sonic wave transceiver further comprises a sound absorbing material extending from the transmitting terminal and elongated along a propagation direction of the first sonic wave. 
     According to a third embodiment of the present disclosure, a frequency of the first sonic wave and the second sonic wave is between 50 KHz and 70 KHz. 
     Yet another aspect of the invention provides a positioning method. The positioning method is used to position a relative position of an object on one side of a display screen. The positioning method includes the following steps: (a) disposing a first sonic wave transceiver and a second sonic wave transceiver around the display screen; (b) utilizing the first sonic wave transceiver and the second sonic wave transceiver to generate a first sonic wave and a second sonic wave, respectively, and a frequency of the first sonic wave and the second sonic wave being set between 50 KHz and 70 KHz; and (c) calculating the position of the object relative to the display screen in accordance with a first reflected sonic wave and a second reflected sonic wave generated in accordance with the first sonic wave and the second sonic wave. 
     In summary, the technical solution of the present disclosure has obvious advantages and beneficial effects as compared with the prior art. Through the above technical solution, considerable advances in technology and extensive industrial applicability can be achieved. The sensing device and positioning method provided by the present disclosure have a high detection update rate and are suitable to be applied to the touch application for large-sized panels. 
     It is to be understood that both the foregoing general description and the following detailed description are by examples, and are intended to provide further explanation of the invention as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. In the drawings, 
         FIG. 1  is a schematic diagram of a sensing device according to one embodiment of the present disclosure; 
         FIG. 2A  is a graph illustrating curves of frequency of a first and second sonic waves versus reflection intensity by different materials according to one embodiment of the present disclosure; 
         FIG. 2B  is a schematic diagram of a vertical beam angle of a first sonic wave according to one embodiment of the present disclosure; 
         FIG. 2C  is a schematic diagram of a horizontal beam angle of a first sonic wave according to one embodiment of the present disclosure; 
         FIG. 2D  is a graph illustrating a relation between a frequency of a first and second sonic waves versus a vertical beam angle according to one embodiment of the present disclosure; 
         FIG. 3A  and  FIG. 3B  are flow charts illustrating positioning calculation of a sensing device according to one embodiment of the present disclosure; 
         FIG. 4  is a waveform graph of a operation of the first sonic wave transceiver according to one embodiment of the present disclosure; 
         FIG. 5  is a schematic diagram of a structure of a first sonic wave transceiver according to one embodiment of the present disclosure; and 
         FIG. 6  is a flow chart of a positioning method  600  according to one embodiment of the present disclosure. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     Reference will now be made in detail to the present embodiments of the invention, examples of which are illustrated in the accompanying drawings. However, the embodiments provided herein are intended as illustrative only since numerous modifications and variations therein will be apparent to those skilled in the art. Description of the operation does not intend to limit the operation sequence. Any devices resulting from recombination of components with equivalent effects are within the scope of the present invention. In addition, drawings are only for the purpose of illustration and not plotted according to the original size. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts. 
     As used herein, “the first”, “the second”, . . . etc. do not refer to the order or priority, nor are they intended to limit the invention. They are merely used to distinguish the devices or operations described with the same technical terms. 
     As used herein, “around”, “about”, or “approximately” shall generally mean within 20 percent, preferably within 10 percent, and more preferably within 5 percent of a given value or range. Numerical quantities given herein are approximate, meaning that the term “around,” “about” or “approximately” can be inferred if not expressly stated. 
     As used herein, both “couple” and “connect” refer to direct physical contact or electrical contact or indirect physical contact or electrical contact between two or more components. Or they can also refer to reciprocal operations or actions between two or more components. 
       FIG. 1  is a schematic diagram of a sensing device  100  according to one embodiment of present disclosure. As shown in  FIG. 1 , the sensing device  100  is configured to mount around a display module  102  to detect an object  104 . The display module  102  includes a display screen  102   a  for displaying an image. 
     The object  104  may be a palm or a finger of a user, a stylus pen, or any other indicator being operated by a user. The sensing device  100  can detect a relative position/coordinate of the palm above the display screen  102   a  by using a sonic wave method when the user performs a touch operation, so that a touch control corresponding to the touch operation is performed on the display module  102 . With such the method, users are able to perform touch operations in a contactless manner (i.e., the object  104  does not need to actually touch the display screen  102   a ) or a contact manner. 
     A number of embodiments are shown as following paragraphs. However, it should be understood that such description is only for illustration of functions and applications of the above sensing device  100  and not to limit the scope of the invention. 
     As shown in  FIG. 1 , the sensing device  100  includes a first sonic wave transceiver  120 , a second sonic wave transceiver  140 , and a control module  160 . The first sonic wave transceiver  120  is configured for transmitting a first sonic wave. The second sonic wave transceiver  140  is configured for transmitting a second sonic wave. The first sonic wave transceiver  120  and the second sonic wave transceiver  140  are further configured for receiving a first reflected sonic wave generated in accordance with the first sonic wave and a second reflected sonic wave generated in accordance with the second sonic wave. The control module  160  is configured for controlling the first sonic wave transceiver  120  and the second sonic wave transceiver  140 . The control module  160  further calculates a position of the object  104  relative to the display module  102  in accordance with the above first reflected sonic wave and the second reflected sonic wave. 
     For example, the control module  160  may control the first sonic wave transceiver  120  and the second sonic wave transceiver  140  to generate the above-mentioned first sonic wave and second sonic wave, and the first and second sonic waves are reflected by the object  104  to generate the first reflected sonic wave and the second reflected sonic wave, respectively. The control module  160  receives the first reflected sonic wave and the second reflected sonic wave through the first sonic wave transceiver  120  and the second sonic wave transceiver  140 , and calculates the relative position of the object  104  based on the first reflected sonic wave and the received second reflected sonic wave. A transmitting terminal and a receiving terminal of each of the first sonic wave transceiver  120  and the second sonic wave transceiver  140  may be integrated together or disposed separately. 
       FIG. 2A  is a graph illustrating curves of frequency of a first and second sonic waves versus reflection intensity by different materials according to one embodiment of the present disclosure. Since the first sonic wave has the same physical characteristics as the second sonic wave, a single curve is depicted in  FIG. 2A  to represent both the first sonic wave and the second sonic wave. When a sound pressure level (SPL) of the first and second reflected sonic waves generated by reflecting the above-mentioned first and second sonic waves by the object  104  has a certain degree of difference from a sound pressure level of sonic waves generated by reflecting the first and second sonic waves by air, the first sonic wave transceiver  120  and the second sonic wave transceiver  140  are allowed to receive the first reflected sonic wave and the second reflected sonic wave reflected from the object  104  accurately. Thus, the control module  160  is able to calculate the relative position of the object  104  correctly. As shown in  FIG. 2A , the first and the second reflected sonic waves generated by reflecting the above-mentioned first and second sonic waves by the object  104  made of different materials (e.g., sound-pressure-level curves  202 ,  204 ,  206 ,  208 ,  210 ,  212  respectively indicates that the first and second sonic waves are reflected by glass, sponge, aluminum, polypropylene, palm, and air) have different sound pressure levels. 
     Typically, most of the touch controls are performed using palms or fingers of users in current touch applications. Hence, as shown in  FIG. 2A , in this embodiment, a frequency of the first and second sonic waves is set between about 50 KHz and about 70 KHz, and a difference between a sound pressure level of sonic waves generated by reflecting the first and second sonic waves by the palm and the sound pressure level of the sonic waves generated by reflecting the first and second sonic waves by air is approximately 20 dB. When compared with the ultrasonic transceiver used in some approaches in which a frequency of a generated sonic wave is mostly set to 48 KHz or 75 KHz. A difference between the sound pressure level of the sonic wave generated by reflecting the sonic wave having the frequency of 48 KHz or 75 KHz by the palm and a sound pressure level of a sonic wave generated by reflecting the sonic wave having the frequency of 48 KHz or 75 KHz by air is only approximately 10 dB. As a result, when the frequency of the first and second sonic waves is set between about 50 KHz and about 70 KHz, the first sonic wave transceiver  120  and the second sonic wave transceiver  140  can receive the first and second reflected sonic waves more accurately. In some embodiments, the frequency of the first and second sonic waves is set greater than 50 KHz, and less than or equal to 70 KHz. In some other embodiments, the frequency of the first and second sonic waves is set between about 55 KHz and about 65 KHz. In yet some other embodiment, the frequency of the first and second sonic waves is set between about 55 KHz and about 60 KHz, such as 57 KHz. 
       FIG. 2B  is a schematic diagram of a vertical beam angle of a first sonic wave according to one embodiment of the present disclosure.  FIG. 2C  is a schematic diagram of a horizontal beam angle of a first sonic wave according to one embodiment of the present disclosure. Generally speaking, a sonic wave signal is one signal having multiple beam angles that indicate different directivities. For example, as shown in  FIG. 2B , the first sonic wave transmitted by the first sonic wave transceiver  120  includes a vertical beam angle in a vertical direction that is perpendicular to the display screen  102   a . Alternatively, as shown in  FIG. 2C , the first sonic wave includes a horizontal beam angle in a horizontal direction that is parallel with the display screen  102   a.    
     In typical applications, the larger the horizontal beam angle is, the greater the horizontal moving distance of the object  104  being detectable by the sensing device  100  is. This circumstance is applicable to the display screen  102   a  having a large area (such as a large-sized display panel). However, the larger the vertical beam angle is, the greater the minimum vertical distance d1 and the maximum vertical distance d2 of the object  104  relative to the display screen  102   a  are, which probably causes misjudgments of the sensing device  100 . For example, in typical touch applications, the sensing device  100  will probably determine that an accidental finger touch by a user to be a normal touch control if the vertical beam angle is excessively large, and an unnecessary touch operation is thus generated. 
       FIG. 2D  is a graph illustrating a relation between a frequency of a first and second sonic waves and a vertical beam angle according to one embodiment of the present disclosure. In  FIG. 2D , the beam angle is defined as the beam angle measured when energies of sonic waves decays to half of their original values. Similarly, since the first sonic wave has the same physical characteristics as the second sonic wave, a single curve is depicted in  FIG. 2D  to represent both the first sonic wave and the second sonic wave. Generally speaking, the higher the frequency of the first and second sonic waves is, the smaller the beam angles corresponding to the frequency that indicate different directivities are. Therefore, in considering the trade-off between frequency, horizontal beam angle, and vertical beam angle, the frequency of the first and second sonic waves generated by the first sonic wave transceiver  120  and the second sonic wave transceiver  140  can be set between about 50 KHz and about 70 KHz as described in the above-mentioned embodiment. As shown in  FIG. 2D , the vertical beam angle of the first and second sonic waves having the frequency set between about 50 KHz and about 70 KHz in the vertical direction perpendicular to the display screen  102   a  is from about 15 to about 40 degrees (see  FIG. 2B ). In some embodiments, the vertical beam angle of the first and second sonic waves having the frequency set between about 50 KHz and about 70 KHz in the vertical direction perpendicular to the display screen  102   a  is more preferably from about 20 to about 35 degrees. In some other embodiments, the vertical beam angle of the first and second sonic waves having the frequency set between about 50 KHz and about 70 KHz in the vertical direction perpendicular to the display screen  102   a  is further more preferably from about 25 to about 30 degrees. In addition, the horizontal beam angle of the above first and second sonic waves in the horizontal direction parallel with the display screen  102   a  is from about 80 to about 100 degrees. In some embodiments, the horizontal beam angle of the above first and second sonic waves in the horizontal direction parallel with the display screen  102   a  is more preferably from about 85 degrees to about 95 degrees. In some other embodiments, the horizontal beam angle of the above first and second sonic waves in the horizontal direction parallel with the display screen  102   a  is further more preferably about 90 degrees (see  FIG. 2C ). 
       FIG. 3A  to  FIG. 3B  are flow charts illustrating positioning calculation of a sensing device  100  according to one embodiment of the present disclosure. In the present embodiment, the control module  160  is further configured for controlling the first sonic wave transceiver  120  to transmit the first sonic wave, and controlling the second sonic wave transceiver  140  to transmit the second sonic wave or controlling the first sonic wave transceiver  120  to transmit the first sonic wave again in accordance with whether the first sonic wave transceiver  120  receives the first reflected sonic wave. A transmission path of the first sonic wave at least partially overlaps the transmission path of the second sonic wave. Because the position of a same object is calculated through the first sonic wave transceiver  120  and the second sonic wave transceiver  140 , the position of the object cannot be estimated correctly if only a position of the object relative to the single sonic wave transceiver is obtained. Hence, if the first sonic wave transceiver  120  does not receive the first reflected sonic wave, the control module  160  controls the first sonic wave transceiver  120  to transmit the first sonic wave again. Only when the second sonic wave transceiver  140  does not receive the first reflected sonic wave, the control module  160  will control the second sonic wave transceiver  140  to transmit the second sonic wave to obtain the position of the object relative to the second sonic wave transceiver  140 . As a result, the redundant transmission of the second sonic wave by the second sonic wave transceiver  140  is avoided. 
     In order to provide a clear explanation, a single sonic wave transceiver is depicted as a sonic wave transmitter and a sonic wave receiver in  FIG. 3A . For illustration, as shown in  FIG. 3A , the control module  160  controls the first sonic wave transmitter  122  in the first sonic wave transceiver  120  to generate the first sonic wave, and the first sonic wave is reflected by the object  104  to generate the first reflected sonic wave. If the first sonic wave receiver  124  receives the first reflected sonic wave, the control module  160  records a time period between transmission of the first sonic wave and reception of the first reflected sonic wave by the first sonic wave transceiver  120  as t1, and calculates a distance of the first sonic wave transceiver  120  relative to the object  104  d1(S1) according to the following equation (1) (i.e., step S 302   a  shown in  FIG. 3A ): 
         d 1( S 1)=( V*t 1)/2  (1)
 
     In the equation (1), d1(S1) denotes the distance measured by the first sonic wave transceiver  120  using the first sonic wave, V denotes a wave velocity of a sonic wave signal. Generally speaking, V is about 340 meters per second (m/s). After the distance d1(S1) is calculated, the control module  160  interrupts an operation of the first sonic wave receiver  124  (i.e., step S 303   a  shown in  FIG. 3A ). After that, if a second sonic wave receiver  144  also receives the first reflected sonic wave, the control module  160  records a time period between transmission of the first sonic wave and reception of the first reflected sonic wave by the second sonic wave transceiver  140  as t2, and calculates a distance of the second sonic wave transceiver  140  relative to the object  104  d2(S1) according to the following equation (2) (i.e., step S 302   b  shown in  FIG. 3A ): 
         d 2( S 1)= V*t 2− d 1( S 1)  (2)
 
     The control module  160  further calculates a position of the object  104  relative to the display module  102  using the above equations (1) and (2) (i.e., step S 304  shown in  FIG. 3A ). Then, the control module  160  controls the first sonic transceiver  120  to transmit the first sonic wave, so as to perform the next sensing operation (i.e., step S 306  shown in  FIG. 3A ). 
     However, as shown in  FIG. 3B , if the second sonic wave receiver  144  does not receive the first reflected sonic wave, the control module  160  cannot calculate the distance d2(S1). Then, the control module  160  further selects to control the second sonic wave transmitter  142  to transmit the second sonic wave (i.e., step S 308  shown in  FIG. 3B ). The second sonic wave is reflected by the object  104  to generate a second reflected sonic wave. When both the first sonic wave receiver  124  and the second sonic wave receiver  144  receive the second reflected sonic wave, the control module  160  records a time period between transmission of the second sonic wave and reception of the second reflected sonic wave by the first sonic wave transceiver  120  as t3, and records a time period between transmission of the second sonic wave and reception of the second reflected sonic wave by the second sonic wave transceiver  140  as t4. The control module  160  also respectively calculates a distance of the first sonic wave transceiver  120  relative to the object  104  d1(S2) according to the following equation (3) (i.e., step S 322   a  shown in  FIG. 3B ) and a distance of the second sonic wave transceiver  140  relative to the object  104  d2(S2) according to the following equation (4) (i.e., step S 322   b  shown in  FIG. 3B ): 
         d 1( S 2)= V*t 3− d 2( S 2)  (3)
 
         d 2( S 2)=( V*t 4)/2  (4)
 
     The control module  160  further combines the above equations (1), (3), and e(4) to obtain the following equation (5): 
         d 1=α* d 1( S 1)+(1−α)* d 1( S 2).  (5)
 
     Where α denotes a distance-weighted index which can be adjusted based on a distance of the first sonic wave transceiver  120  relative to the display module  102  and a distance of the second sonic wave transceiver  140  relative to the display module  102  correspondingly, and 0≦α≦1. In the present embodiment, the control module  160  may calculate a position of the object  104  relative to the display module  102  according to equations (4) and (5) (i.e., step S 324  shown in  FIG. 3B ). After that, the control module  160  controls the first sonic wave transceiver  120  to retransmit the first sonic wave, so as to perform the next sensing operation (i.e., step S 306  shown in  FIG. 3A ). Compared with the prior art in which the number of the sonic wave transceivers is larger than that utilized in the present disclosure, the positioning calculation method proposed by the present disclosure has a lower operational complexity, and the speed of positioning calculation process is thus improved. 
     In the above-mentioned embodiment, the control module  160  can further determine whether the first sonic wave receiver  124  and the second sonic wave receiver  144  receive the first reflected sonic wave or the second reflected sonic wave by setting an interrupt time. For illustration, if the maximum detectable distance of the sensing device  100  is about 50 centimeters (cm), and a wave velocity of the first sonic wave and the second sonic wave is supposed to be about 340 m/s, then the longest time taken to transmit and reflect the sonic wave is about 0.5*2/340=2.94 milliseconds (ms). Hence, the control module  160  may set the interrupt time to about 2.94 ms. If the first sonic wave receiver  124  and the second sonic wave receiver  144  have not received the first reflected sonic wave or the second reflected sonic wave after exceeding 2.94 ms, the control module  160  controls the first sonic wave transceiver  120  or the second sonic wave transceiver  140  to retransmit the sonic wave in a real-time manner. Thus, the detection update rate of the sensing device  100  is increased. 
       FIG. 4  is a waveform graph illustrating operation of the first sonic wave transceiver according to one embodiment of the present disclosure. Except for setting the interrupt time, the control module  160  may be further configured for monitoring whether an intensity of the first reflected sonic wave is greater than or equal to a threshold value VTH. When the intensity of the first reflected sonic wave is greater than or equal to the threshold value VTH, the control module  160  interrupts monitoring of the intensity of the first reflected sonic wave, and calculates a distance of the object  104  relative to the first sonic wave transceiver  120  in accordance with a time at which the intensity of the first reflected sonic wave is greater than or equal to the threshold value VTH and a time at which the first sonic wave is transmitted. 
     For illustration, as shown in  FIG. 4 , the first sonic wave transceiver  120  transmits the first sonic wave at a time TA, and the control module  160  detects that the intensity of the first reflected sonic wave received by the first sonic wave receiver  122  is greater than the threshold value VTH at a time TB. The control module  160  thus determines that the first sonic wave receiver  122  has received the first reflected sonic wave correctly. As a result, the control module  160  calculates the distance of the first sonic wave transceiver  120  relative to the object  104  d1(S1) based on a time difference between TA and TB (such as t1 in the above equation (1)). Similarly, the same configuration may be set for the second reflected sonic wave, and a description in this regard is not provided. Typically, the above threshold value may be adjusted depending on the actual environment. The threshold value must be greater than the environment noise of the actual environment, so as to avoid that the control module  160  mistakes the environment noise for the first or the second reflected sonic wave. As compared with the prior art in which each of the sonic wave transceivers must receive the individual sonic signal reflected from the object, the control module  160  is allowed to interrupt the sensing operation of the first sonic wave transceiver  120  or the second sonic wave transceiver  140  in a real-time manner, when the intensity of first reflected sonic wave or the intensity of the second reflected sonic wave received by the first sonic wave transceiver  120  or the second sonic wave transceiver  140  is greater than the threshold value, by setting the threshold value VTH according to the present embodiment. In this manner, the control module  160  is able to improve its speed of determining whether the first sonic wave transceiver  120  and the second sonic wave transceiver  140  have received the first or the second reflected sonic wave correctly, and the process speed when calculating the position of the object  104  is father improved. As a result, the detection update rate of the sensing device  100  is effectively improved. 
       FIG. 5  is a schematic diagram of a structure of a first sonic wave transceiver according to one embodiment of the present disclosure. In the present embodiment, the first sonic wave transceiver  120  has a transmitting terminal  126  and sound absorbing materials  128 . The transmitting terminal  126  is configured for generating the above-mentioned first sonic wave. The sound absorbing materials  128  extend from the transmitting terminal  126  and are elongated along a propagation direction of the first sonic wave. For example, the acoustic absorbing materials  128  may be acoustic boards or acoustic absorbers, and are disposed on two sides of the transmitting terminal  126 . Hence, the first sonic wave transceiver  120  may further reduce the above-mentioned vertical beam angle so as to improve the accuracy of the sensing device  100 . Likewise, the second sonic wave transceiver  140  may have the same structure. 
     It is should be noticed that there are two sonic wave transceivers in each of the above-mentioned embodiments. However, the sensing device  100  may further include numerous sonic wave transceivers, and calculates the position of the object  104  according to the positioning calculation flows  300 ,  320  shown in  FIG. 3A  and  FIG. 3B . Those of ordinary skill in the art may adjust the number of the sonic wave transceivers as required by the actual application environment, and the present invention is not limited in this regard. 
     In addition, the above control module  100  may be implemented in software or hardware/firmware. For illustration, if execution speed and accuracy are both the first considerations, the control module  160  may be basically implemented in hardware. For example, the control module  160  may be a processing unit or a field-programmable gate array (FPGA). If design flexibility is the first consideration, the control module  160  may be basically implemented in software. However, the present disclosure is not limited in this regard, those of ordinary skill in the art may flexibly select the implementation method for the control module  160  as required. 
     Another aspect of the present invention provides a positioning method. The positioning method is used to position a relative position of an object on one side of a display screen (such as the object  104  and the display screen  102   a  shown in  FIG. 1 ).  FIG. 6  is a flow chart of a positioning method  600  according to one embodiment of the present disclosure. As shown in  FIG. 6 , the positioning method  600  comprises a step S 620 , a step S 640 , and a step S 660 . 
     In step S 620 , the first sonic wave transceiver  120  and the second sonic wave transceiver  140  are disposed around the display screen  102   a , as shown in  FIG. 1 . 
     In step S 640 , the first sonic wave transceiver  120  and the second sonic wave transceiver  140  are utilize to respectively generate a first sonic wave and a second sonic wave. As described previously, the frequency of the first sonic wave and the second sonic wave may be set between about 50 KHz and about 70 KHz. The vertical beam angle of the first and second sonic waves in the vertical direction perpendicular to the display screen  102   a  is from about 15 to about 40 degrees (see  FIG. 2B ). In addition, the above-mentioned horizontal beam angle of the first and second sonic waves in the horizontal direction parallel with the display screen  102   a  is from about 80 to about 100 degrees. 
     In step S 660 , a position of the object  104  relative to the display screen  102   a  is calculated based on a first reflected sonic wave and a second reflected sonic wave generated by reflecting the first sonic wave and the second sonic wave. In step S 660 , the second sonic wave transceiver  140  may further transmit the second sonic wave or the first sonic wave transceiver  120  may further transmit the first sonic wave again depending on whether the first sonic wave transceiver  120  receives the first reflected sonic wave. In addition, a transmission path of the first sonic wave at least partially overlaps a transmission path of the second sonic wave. The relative position of the object  104  can be calculated, for example, according the above equations (1)-(5) and the above operation flows shown in  FIG. 3A  and  FIG. 3B . 
     Similarly, the step S 660  can be performed by monitoring whether an intensity of the first reflected sonic wave is greater than or equal to a threshold value VTH, as shown in  FIG. 4 . When the intensity of the first reflected sonic wave is greater than or equal to a threshold value VTH, interrupt the monitoring of the intensity of the first reflected sonic wave and calculate a distance of the object  104  relative to the first sonic wave transceiver  120  based on a time at which the intensity of the first reflected sonic wave is greater than or equal to the threshold value VTH and a time at which the first sonic wave is transmitted. 
     In summary, the present disclosure discloses the sensing device and the positioning method that have a higher accuracy and a higher detection rate than the prior art device and method when applied to detecting palms of users. In addition, the sensing device and positioning method in the present disclosure are suitable to be applied to the touch application for large-sized panels. 
     Although the present invention has been described in considerable detail with reference to certain embodiments thereof, other embodiments are possible. Therefore, the spirit and scope of the appended claims should not be limited to the description of the embodiments contained herein. 
     It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.