Patent Publication Number: US-2018048554-A1

Title: Monitoring apparatus and related method

Description:
BACKGROUND 
     The Internet of things (IoT) is a concept of interconnection among physical devices, vehicles, buildings, and other items. IoT is expected to offer advanced connectivity of devices, systems, and services that goes beyond machine-to-machine (M2M) communications and covers a variety of protocols, domains, and applications. The interconnection of these devices is expected to in nearly all fields, while also enabling advanced applications like a smart grid, and expanding to areas such as smart cities. The technology of Mesh Network is wildly used in IOT application. However, this technology has drawbacks of limited node number, communication range, and data rate. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying figures. It is noted that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion. 
         FIG. 1  is a diagram illustrating a mesh network system in accordance with some embodiments. 
         FIG. 2  is a diagram illustrating a time synchronization between two monitoring devices in accordance with some embodiments. 
         FIG. 3  is a diagram illustrating an example of transmitting an instruction signal in the mesh network system in accordance with some embodiments. 
         FIG. 4  is a diagram illustrating an example of transmitting an instruction signal in the mesh network system in accordance with some embodiments. 
         FIG. 5  is a diagram illustrating a monitoring device in accordance with some embodiments. 
         FIG. 6  is a diagram illustrating two monitoring devices in accordance with some embodiments. 
         FIG. 7  is a flowchart illustrating a monitoring method in accordance with some embodiment. 
         FIG. 8A  is a schematic view illustrating a coordinate sensing device according to one embodiment of the present invention. 
         FIG. 8B  is a schematic view illustrating the use of a coordinate sensing device of the present invention to output a coordinate of an object according to one embodiment. 
         FIG. 8C  is a schematic view illustrating the use of a coordinate sensing device of the present invention to output a coordinate of an object according to another embodiment. 
         FIG. 8D  is a schematic view illustrating the use of a coordinate sensing device of the present invention to output a coordinate of an object according to another embodiment. 
         FIG. 8E  is a schematic view illustrating the use of a coordinate sensing device of the present invention to output a coordinate of an object according to another embodiment. 
         FIG. 8F  is a top view illustrating the use of a coordinate sensing device of the present invention to scan an object according to another embodiment. 
         FIG. 8G  is an oscillogram of a receiving signal generated by a present receiver according to one embodiment. 
         FIG. 8H  is a top view illustrating the use of a coordinate sensing device of the present invention to scan an object according to another embodiment. 
         FIG. 8I  is an oscillogram of a receiving signal generated by a present receiver according to another embodiment. 
         FIG. 8J  is a top view illustrating the use of a coordinate sensing device of the present invention to output a three-dimensional coordinate of an object according to one embodiment. 
         FIG. 8K  is a top view illustrating the use of a coordinate sensing device of the present invention to scan an object according to another embodiment. 
         FIG. 9A  is a schematic view illustrating a coordinate sensing device according to one embodiment of the present invention. 
         FIG. 9B  is a schematic view illustrating the use of a coordinate sensing device of the present invention to output a coordinate of an object according to one embodiment. 
         FIG. 9C  is a schematic view illustrating the use of a coordinate sensing device of the present invention to output a coordinate of an object according to another embodiment. 
         FIG. 9D  is a schematic view illustrating the use of a coordinate sensing device of the present invention to output a coordinate of an object according to another embodiment. 
         FIG. 9E  is schematic view illustrating the use of a coordinate sensing device of the present invention to output a coordinate of an object according to another embodiment. 
         FIG. 9F  is a top view illustrating the use of a coordinate sensing device of the present invention to scan an object according to another embodiment. 
         FIG. 9G  is an oscillogram of a receiving signal generated by a present receiver according to one embodiment. 
         FIG. 9H  is a top view illustrating the use of a coordinate sensing device of the present invention to scan an object according to another embodiment. 
         FIG. 9I  is an oscillogram of a receiving signal generated by a present receiver according to another embodiment. 
         FIG. 9J  is a top view illustrating the use of a coordinate sensing device of the present invention to scan two objects according to one embodiment. 
         FIG. 9K  is a top view illustrating the use of a coordinate sensing device of the present invention to scan an object according to another embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     The following disclosure provides many different embodiments, or examples, for implementing different features of the provided subject matter. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. 
     Embodiments of the present disclosure are discussed in detail below. It should be appreciated, however, that the present disclosure provides many applicable inventive concepts that can be embodied in a wide variety of specific contexts. The specific embodiments discussed are merely illustrative and do not limit the scope of the disclosure. 
     Further, spatially relative terms, such as “beneath,” “below.” “lower,” “above,” “upper”, “lower”, “left”, “right” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly. It will be understood that when an element is referred to as being “connected to” or “coupled to” another element, it may be directly connected to or coupled to the other element, or intervening elements may be present. 
     Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the disclosure are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in the respective testing measurements. Also, as used herein, the term “about” generally means within 10%, 5%, 1%, or 0.5% of a given value or range. Alternatively, the term “about” means within an acceptable standard error of the mean when considered by one of ordinary skill in the art. Other than in the operating/working examples, or unless otherwise expressly specified, all of the numerical ranges, amounts, values and percentages such as those for quantities of materials, durations of times, temperatures, operating conditions, ratios of amounts, and the likes thereof disclosed herein should be understood as modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the present disclosure and attached claims are approximations that can vary as desired. At the very least, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Ranges can be expressed herein as from one endpoint to another endpoint or between two endpoints. All ranges disclosed herein are inclusive of the endpoints, unless specified otherwise. 
       FIG. 1  is a diagram illustrating a mesh network system  100  in accordance with some embodiments. The mesh network system  100  comprises a plurality of operational devices  102   a ˜ 102   p  and a plurality of monitoring devices  102 ,  104 ,  106 , and  108 . The operational devices  102   a ˜ 102   p  are distributed on a large-scale field. Each of the operational devices  102   a ˜ 102   p  is configured to perform a predetermined function. For example, the predetermined function may be an illumination control of a lighting device. For brevity, the operational devices  102   a ˜ 102   p  are illustrated as a plurality of nodes respectively as shown in  FIG. 1 . The operations of the operational devices  102   a ˜ 102   p  are controlled by a controller (not shown). The controller may be wirelessly connected or wire-coupled to the operational devices  102   a ˜ 102   p . The controller may transmit instruction(s) to one or more of the operational devices  102   a ˜ 102   p  for controlling their predetermined functions via a Gateway (not shown). The Gateway may be wirelessly connected or wire-coupled to the operational devices  102   a ˜ 102   p.    
     Furthermore, each of the operational devices  102   a ˜ 102   p  is further arranged to relay data or instruction for the network. Therefore, all the operational devices  102   a ˜ 102   p  are arranged to corporately distribute data in the network. Ideally, the operational devices  102   p  are all directly or indirectly connected with each other. For example, when one of the operation devices  102   a ˜ 102   p  receives an instruction from the Gateway, and when the operation device is functional work, the operation device may pass the instruction to the next operation device(s). The next operation device may pass the instruction to the another operation device(s) when the next operation device is functional work. Accordingly, the instruction may be distributed to all of the operational devices  102   a ˜ 102   p . According to some embodiments, the connection between two operational devices may be established by using any existing wireless communication technique, e.g. Zigbee. 
     However, in practice, some of the operational devices  102   a ˜ 102   p  may fail to perform their predetermined functions due to, for example, their limited lifetime. In the large-scale field, the failed operational devices may not easily be founded manually among the huge number of operational devices. Accordingly, in the present embodiment, a plurality of monitoring devices, e.g. the monitoring devices  102 ,  104 ,  106 , and  108 , are developed to automatically monitor the operational devices  102   a ˜ 102   p  respectively. According to the present embodiment, the mesh network system  100  may be applied to monitor a lighting system of a large-scale field, such as a lighting system in a shopping mall or a multi-story building. 
     According to some embodiments, the monitoring device  102  is arranged to monitor the operation of the operational devices  102   a ˜ 102   d . The monitoring device  104  is arranged to monitor the operation of the operational devices  102   e ˜ 102   h . The monitoring device  106  is arranged to monitor the operation of the operational devices  102   i ˜ 102   l . The monitoring device  108  is arranged to monitor the operation of the operational devices  102   m ˜ 102   p . It is noted that the number of monitoring devices and the number of operational devices monitored by each monitoring device are just examples, which are not the limitation of the present invention. According to the present embodiments, at least two monitoring devices are used to monitor a plurality monitoring devices in a field. A monitoring device may be capable of monitoring a predetermined or limited number of operational devices. The number of the monitoring devices may be adjusted depending on the number of the operational devices. 
     The monitoring devices  102 ,  104 ,  106 , and  108  are further arranged to wirelessly transmit the monitored results corresponding to the operational devices  102   a ˜ 102   p  to an external or remote processing system  110 . The remote processing system  110  may be a cloud computing system or a cloud server. The remote processing system  110  at least comprises a processing device for analyzing or processing the monitored results received from the monitoring devices  102 ,  104 ,  106 , and  108 . It is noted that cloud computing is a type of Internet-based computing that provides shared computer processing resources and data to computers and other devices on demand. It is a model for enabling ubiquitous, on-demand access to a shared pool of configurable computing resources (e.g., computer networks, servers, storage, applications and services), which can be rapidly provisioned and released with minimal management effort. 
     According to some embodiments, the connection between a monitoring device (e.g. the monitoring device  102 ) and the corresponding operational devices (e.g. the operational devices  102   a ˜ 102   d ) is implemented by a connecting device for conveying the corresponding acknowledgement signals respectively. The connecting device may comprise a plurality of connecting wires or lines connected between the monitoring device and the corresponding operational devices respectively. For example, in  FIG. 1 , the connecting wires between the monitoring device  102  and the operational devices  102   a ˜ 102   d  are illustrated as  112   a ˜ 112   d  respectively. 
     According to some embodiments, the connecting device may be implemented by an Universal Asynchronous Receiver/Transmitter (UART). The UART may be a microchip with programming that controls the interface of a monitoring device (e.g. the monitoring device  102 ) to its attached operational devices (e.g. the operational devices  102   a ˜ 102   d ). 
     According to some embodiments, the connecting device may be implemented by an Inter-Integrated Circuit (I2C). The I2C is used for attaching the operational devices (e.g. the operational devices  102   a ˜ 102   d ) to the corresponding monitoring device (e.g. the monitoring device  102 ) in short-distance, intra-board communication. The I2C may be a multi-master, multi-slave, packet switched, single-ended, serial computer bus. 
     According to some embodiments, the connecting device may be implemented by a Serial Peripheral Interface bus (SPI). The SPI is a synchronous serial communication interface specification used for short distance communication, primarily in embedded systems. An SPI device communicate in full duplex mode using a master-slave architecture with a single master (e.g. the monitoring device  102 ) and multiple slave devices (e.g. the operational devices  102   a ˜ 102   d ). Multiple slave devices are supported through selection with individual slave select (SS) lines. 
     In addition, the monitoring devices  102 ,  104 ,  106 , and  108  are capable of communicating with each other by using any existing wireless communication technique. Specifically, the operating clock signals of the monitoring devices  102 ,  104 ,  106 , and  108  are time synchronized with each other by using the technique of Reference Broadcast Synchronization (RBS).  FIG. 2  is a diagram illustrating the time synchronization between two monitoring devices in the field of the mesh network system  100  in accordance with some embodiments. For brevity, the monitoring device  102  and the monitoring device  104  are used to illustrate the operation of time synchronization of the present embodiment. It is noted that the time synchronization can be expanded to the synchronization among the monitoring devices  102 ,  104 ,  106 , and  108 . Specifically, during the synchronization, a beacon is wirelessly transmitted to the monitoring devices  102  and  104 . The beacon may be sent from a cloud computing system or a cloud server. For example, the cloud computing system may be the remote processing system  110 . The monitoring device  102  and the monitoring device  104  may exchange the timing information of the received beacons to perform the time synchronization between their operating clock signals respectively. For example, in  FIG. 2 , a packet is wirelessly transmitted to the monitoring device  104  from the monitoring device  102 . According to some embodiments, a timestamp may be attached to an end of the packet. The timestamp indicates or includes the receiving time of the beacon received by the monitoring device  102 . In  FIG. 2 , the curve  202  indicates the time domain of transmitting the packet by the monitoring device  102 . The curve  204  indicates the time domain of receiving the packet by the monitoring device  104 . The monitoring device  102  transmits the packet  202  at time ta, and transmits the corresponding timestamp  206  at time tb. The monitoring device  104  receives the packet  204  at time tc, and receives the corresponding timestamp  208  at time td. The monitoring device  104  is arranged to read or decipher the timestamp  206  to obtain the receiving time of the beacon received by the monitoring device  102 . When the beacon receiving time of the monitoring device  102  is obtained by the monitoring device  104 , the monitoring device  104  may calculate the offset between the beacon receiving time of the monitoring device  102  and the beacon receiving time of the monitoring device  104 . According to some embodiments, the offset corresponds to the phase shift between the operating clock signal of the monitoring device  102  and the operating clock signal of the monitoring device  104 . Accordingly, the monitoring device  102  and the monitoring device  104  may synchronize their operating clock signals respectively based on the offset or the phase shift. Although a propagation time Ts, e.g. the time difference between tb and td, exists between the packet  202  and the packet  204 , the propagation time Ts may be ignored if the transmission range is relatively small. 
     It is noted that, by using the technique of RBS, the time synchronization between the monitoring devices  102  and  104  is based on the offset between the beacon receiving time, and the time synchronization between the monitoring devices  102  and  104  is not based on the sending time of the beacon sent from the remote processing system  110 . Therefore, the technique of RBS removes the uncertainty of the sender by removing the sender, i.e. the remote processing system  110 , from the critical path. By removing the sender, the only uncertainty is the propagation and receiving times of the monitoring devices  102  and  104 . Therefore, the monitoring devices  102  and  104  may obtain relatively precise clock synchronization. 
       FIG. 3  is a diagram illustrating an example of transmitting an instruction signal Si in the mesh network system  100  in accordance with some embodiments. The instruction signal Si is arranged to control an operational device to perform its predetermined function. For example, if the operational device is a lighting device, the instruction signal Si is used to turn-on, turn-off, or adjusting illumination of the lighting device. For brevity, the operation of the monitoring devices  102 ,  104 ,  106 , and  108  is described by transmitting the instruction signal Si from the operational device  102   a  to the operational device  102   n  by an order of the operational device  102   a , the operational device  102   b , the operational device  102   c , the operational device  102   g , the operational device  102   k , the operational device  102   o , and the operational device  102   n . However, this is not a limitation of the present embodiment. 
     At time t 1 , when the predetermined function of the operational device  102   a  works, the instruction signal Si is transmitted by the operational device  102   a  to the operational device  102   b , and the monitoring device  102  records the transmitting time t 1 . At time t 2 , the instruction signal Si is received by the operational device  102   b , and the monitoring device  102  records the receiving time t 2 . At time t 3 , when the predetermined function of the operational device  102   b  works, the instruction signal Si is transmitted by the operational device  102   b  to the operational device  102   c , and the monitoring device  102  records the transmitting time t 3 . When the instruction signal Si is transmitted to the operational device  102   c  from the operational device  102   b , the monitoring device  102  transmits a first detecting event or packet Sd 1  including the information of times t 1 , t 2 , and t 3  to the remote processing system  110 . 
     At time t 4 , the instruction signal Si is received by the operational device  102   c , and the monitoring device  104  records the receiving time t 4 . At time t 5 , when the predetermined function of the operational device  102   c  works, the instruction signal Si is transmitted by the operational device  102   c  to the operational device  102   g , and the monitoring device  104  records the transmitting time t 5 . At time t 6 , the instruction signal Si is received by the operational device  102   g , and the monitoring device  104  records the receiving time t 6 . At time t 7 , when the predetermined function of the operational device  102   g  works, the instruction signal Si is transmitted by the operational device  102   g  to the operational device  102   k , and the monitoring device  104  records the transmitting time t 7 . When the instruction signal Si is transmitted to the operational device  102   k  from the operational device  102   g , the monitoring device  104  transmits a second detecting event Sd 2  including the information of times t 4 , t 5 , t 6 , and t 7  to the remote processing system  110 . 
     At time t 8 , the instruction signal Si is received by the operational device  102   k , and the monitoring device  106  records the receiving time t 8 . At time t 9 , when the predetermined function of the operational device  102   k  works, the instruction signal Si is transmitted by the operational device  102   k  to the operational device  102   o , and the monitoring device  106  records the transmitting time t 9 . At time t 10 , the instruction signal Si is received by the operational device  102   o , and the monitoring device  106  records the receiving time t 10 . At time t 11 , when the predetermined function of the operational device  102   o  works, the instruction signal Si is transmitted by the operational device  102   o  to the operational device  102   n , and the monitoring device  106  records the transmitting time t 11 . When the instruction signal Si is transmitted to the operational device  102   n  from the operational device  102   o , the monitoring device  106  transmits a third detecting event Sd 3  including the information of times t 8 , t 9 , t 10 , and t 11  to the remote processing system  110 . 
     At time t 12 , the instruction signal Si is received by the operational device  102   n , and the monitoring device  108  records the receiving time t 12 . When the instruction signal Si is received by the operational device  102   n  and the predetermined function of the operational device  108   a  works, the monitoring device  108  transmits a fourth detecting event Sd 4  including the information of time t 12  to the remote processing system  110 . 
     According to some embodiment, when the remote processing system  110  receives the first detecting event Sd 1 , the remote processing system  110  is arranged to process or analyze the first detecting event Sd 1  in order to determine if the predetermined functions of the operational device  102   a  and the operational device  102   b  work. When the remote processing system  110  founds that the first detecting event Sd 1  includes the information of times t 1 , t 2 , and t 3 , it means that the instruction signal Si is successfully transmitted to the operational device  102   c  by an order of the operational device  102   a , the operational device  102   b , and the operational device  102   c . Then, the remote processing system  110  determines that the operational device  102   a  and the operational device  102   b  are functional-work. However, when the remote processing system  110  founds that the detecting event merely includes the information of times t 1  and t 2 , it means that the instruction signal Si is just transmitted to the operational device  102   b  from the operational device  102   a , and the instruction signal Si is not transmitted to the operational device  102   c  from the operational device  102   b . Then, the remote processing system  110  determines that the operational device  102   a  is functional-work and the operational device  102   b  is functional-fail. In other words, when the operational device  102   b  is functional-fail, the operational device  102   b  merely receives the instruction signal Si at time t 2 , and the operational device  102   b  does not transmit the instruction signal Si to the operational device  102   c  at time t 3 . When operational device  102   b  does not transmit the instruction signal Si to the operational device  102   c  at time t 3 , the first detecting event Sd 1  may not has the information of time t 3 . It is noted that the remote processing system  110  uses the similar method to determine the functional of the following operational devices  102   c ,  102   g ,  102   k ,  102   o , and  102   n  based on the received detecting events Sd 2 , Sd 3 , and Sd 4 . Thus, the detailed description is omitted for brevity. 
     Accordingly, the operation of the operational devices  102   a ˜ 102   p  in the large-scale field may be effectively monitored by the monitoring devices  102 ,  104 ,  106 , and  108  respectively. 
     According to some embodiments, if the operational device  102   b  is functional-fail, the instruction signal Si may re-transmit to the operational device  102   f  from the operational device  102   a  as shown in  FIG. 4 .  FIG. 4  is a diagram illustrating an example of transmitting an instruction signal Si′ in the mesh network system  100  in accordance with some embodiments. For brevity, the operation of the monitoring devices  102 ,  104 ,  106 , and  108  is described by transmitting the instruction signal Si′ from the operational device  102   a  to the operational device  102   n  by an order of the operational device  102   a , the operational device  102   b , the operational device  102   f , the operational device  102   c , the operational device  102   g , the operational device  102   k , the operational device  102   o , and the operational device  102   n . However, this is not a limitation of the present embodiment. 
     At time t 1 ′, when the predetermined function of the operational device  102   a  works, the instruction signal Si′ is transmitted by the operational device  102   a  to the operational device  102   b , and the monitoring device  102  records the transmitting time t 1 ′. However, the operational device  102   b  does not receive the instruction signal Si′ because the operational device  102   b  is functional-fail. Then, at time t 2 ′, the operational device  102   a  re-transmits the instruction signal Si′ to another operational device (i.e.  102   f ), which is also monitored by the monitoring device  102 , and the monitoring device  102  records the transmitting time t 2 ′. At time t 3 ′, the instruction signal Si′ is received by the operational device  102   f , and the monitoring device  102  records the receiving time t 3 ′. At time t 4 ′, when the predetermined function of the operational device  102   f  works, the instruction signal Si′ is transmitted by the operational device  102   f  to the operational device  102   c , and the monitoring device  102  records the transmitting time t 4 ′. When the instruction signal Si′ is transmitted to the operational device  102   c  from the operational device  102   f , the monitoring device  102  transmits a first detecting event or packet Sd 1 ′ including the information of times t 1 ′, t 2 ′, t 3 ′, t 4 ′ to the remote processing system  110 . 
     When the remote processing system  110  receives the first detecting event Sd 1 ′, the remote processing system  110  is arranged to process or analyze the first detecting event Sd 1 ′ in order to determine the operation of the operational device  102   a , the operational device  102   b , and the operational device  102   f . When the remote processing system  110  founds that the first detecting event Sd 1 ′ includes the information of times t 1 ′, t 2 ′, t 3 ′, and t 4 ′, it means that the instruction signal Si′ is successfully transmitted to the operational device  102   c  by an order of the operational device  102   a , the operational device  102   b , the operational device  102   a , the operational device  102   f , and the operational device  102   c . Accordingly, the remote processing system  110  determines that the operational device  102   a  and the operational device  102   f  are functional-work, and the operational device  102   b  is functional-fail. 
     The instruction signal Si is then transmitted to the operational device  102   n  from the operational device  102   c  by an order of the operational device  102   c , the operational device  102   g , the operational device  102   k , the operational device  102   o , and the operational device  102   n . The monitoring devices  104 ,  106 , and  108  transmit the corresponding second detecting event Sd 2 ′, third detecting event Sd 3 ′, and fourth detecting event Sd 4 ′ to the remote processing system  110 . The remote processing system  110  is arranged to determine the operation of the operational devices  102   c ,  102   g ,  102   k ,  102   o , and  102   n  based on the second detecting event Sd 2 ′, third detecting event Sd 3 ′, and fourth detecting event Sd 4 ′ respectively. As the operation is similar to the operation of  FIG. 3 , the detailed description is omitted for brevity. 
     According to some embodiments, the monitoring devices  102 ,  104 ,  106 , and  108  are configured to have a similar configuration.  FIG. 5  is a diagram illustrating the operation of one monitoring device (e.g. the monitoring device  102 ) in accordance with some embodiments. 
     For the purpose of description, the operational device  102   b  is also shown in  FIG. 5 . The monitoring device  102  is arranged to monitor the operation of the operational device  102   b . According to some embodiments, the monitoring device  102  comprises a power supply unit  502 , a networking unit  504 , a time synchronization unit  506 , a signal measuring and analyzing unit  508 , and a connecting device  510 . In addition, the operational device  102   b  comprises a General Purpose Input/Output (GPIO) pin  102   b _ 1 . 
     For the monitoring device  102 , the power supply unit  502  is arranged to supply power to the operational device  102   b , the networking unit  504 , the time synchronization unit  506 , and the signal measuring and analyzing unit  508 . According to some embodiments, the power supply unit  502  may comprises a converter for converting AC (Alternative Current) or DC (Direct Current) signal into the voltage levels required by the operational device  102   b , the networking unit  504 , the time synchronization unit  506 , and the signal measuring and analyzing unit  508  respectively. For example, the voltage level may be 5V or 3.3V. 
     The time synchronization unit  506  is arranged to generate a clock signal Sck 1 . The clock signal Sck 1  is synchronized with the clock signals of other monitoring devices (not shown in  FIG. 5 ) via the technique of RBS. By using the technique of RBS, the time error between the clock signal Sck 1  and the other clock signals can be reduced to a relatively small range. When the time error between the clock signal Sck 1  and the other clock signals is small, the information in the timestamp of the packet generated or received by the monitoring device  102  is relatively accurate. For example, the time error may be smaller than 1 us, e.g. 50 ns. 
     For example, the clock signal Sck 1  of the time synchronization unit  506  is set to be the reference clock or reference time. Then, the other clock signals of the other monitoring devices synchronize with the clock signal Sck 1  by using the technique of RBS. 
     According to some embodiments, the time synchronization unit  506  may synchronize with the time synchronization units of other monitoring devices via the technique of GPS. For example, when the mesh network system  100  is applied in a wide environment, the time synchronization unit  506  performs synchronization with the other time synchronization units through GPS. 
     Furthermore, the time synchronization unit  506  may transmit an impulse signal Sip to the signal measuring and analyzing unit  508 . For example, the time synchronization unit  506  may transmit the impulse signal Sip to the signal measuring and analyzing unit  508  in every 10 ms. The signal measuring and analyzing unit  508  is arranged to reset or start a counting time upon the receiving of the impulse signal Sip. According to some embodiments, the time synchronization unit  506  and the signal measuring and analyzing unit  508  are arranged to have a crystal oscillator (or a counter) respectively. The signal measuring and analyzing unit  508  is arranged to use its crystal oscillator or the counter to count the time difference between two contiguous impulse signals Sip received from the time synchronization unit  506 . As mentioned above, the time difference between two contiguous impulse signals Sip received from the time synchronization unit  506  is 10 ms, thus the signal measuring and analyzing unit  508  can use the time space of 10 ms to modify or correct the counting time. By using the time difference of two impulse signals Sip to be the reference time, the error of the counting time of the signal measuring and analyzing unit  508  can be less than 1 us. 
     The connecting device  510  is coupled between the signal measuring and analyzing unit  508  and the operational device  102   b . The connecting device  510  may be a Serial Peripheral Interface (SPI) bus, an Universal Asynchronous Receiver/Transmitter (UART), or an Inter-Integrated Circuit (I2C) coupled to the GPIO pin  102   b _ 1  of the operational device  102   b . The signal measuring and analyzing unit  508  is arranged for analyzing an acknowledgement signal Sk 1  on the connecting device  510  received from the operational device  102   b  to obtain the time at which the operational device  102   b  transmitting the instruction signal Si. Every time the operational device  102   b  performs an operation of wireless communicating, the operational device  102   b  transmits a copy (i.e. the acknowledgement signal Sk 1 ) of received packet or transmitted packet to the signal measuring and analyzing unit  508  via the connecting device  510 . When the state of the operational device  102   b  is changed, e.g., from the normal operation mode to the sleep mode, the operational device  102   b  also transmits the state (i.e. the acknowledgement signal Sk 1 ) to the signal measuring and analyzing unit  508  via the connecting device  510 . 
     Every time the operational device  102   b  receives packet and the state of GPIO pin  102   b _ 1  is changed, the signal measuring and analyzing unit  508  records the packet and the state. The signal measuring and analyzing unit  508  also records the corresponding occur time of the packet and the state. According to some embodiments, when the state of the GPIO pin  102   b _ 1  is changed from a first level to a second level different from the first level, the operational device  102   b  may record the instant timestamp and the instant level for generating an event, i.e. the acknowledgement signal Sk 1 . The acknowledgement signal Sk 1  is transmitted to the networking unit  504  via the connecting device  510 . The networking unit  504  buffers the acknowledgement signal Sk 1  and transmits the acknowledgement signal Sk 1  to the signal measuring and analyzing unit  518 . 
     For example, when the operational device  102   b  receives a packet, the operational device  102   b  changes the state of the GPIO pin  102   b _ 11  to a high voltage level from a low voltage level, and records the instant timestamp of receiving the packet. Then, the operational device  102   b  generates an event packet including the information of the instant timestamp and the high voltage level, and transmits the event packet to the networking unit  504  via the connecting device  510 . When the operational device  102   b  transmits the event packet to the networking unit  504 , the state of the GPIO pin  102   b _ 1  remains the high voltage level. When transmission of the event packet is end, the operational device  102   b  changes the state of the GPIO pin  102   b _ 1  to the low voltage level from the high voltage level. Accordingly, the signal measuring and analyzing unit  508  may obtain the receiving time and the transmission time (or packet length) of the packet received by the operational device  102   b  according to the changing state of the GPIO pin  102   b _ 1 . 
     Furthermore, the signal measuring and analyzing unit  508  may use to update the firmware of the operational device  102   b . The signal measuring and analyzing unit  508  may also use to reset or turn-off the operational device  102   b . According to some embodiments, the signal measuring and analyzing unit  508  may receive an instruction from Internet via the networking unit  504  to update the firmware of the operational device  102   b . The signal measuring and analyzing unit  508  may update the firmware of the operational device  102   b  by using the bootstrap loader (BLS) function of the operational device  102   b.    
     The networking unit  504  may receive the packet event, and transmit the packet event (i.e. Sd 1 ) to a predetermined server. The predetermined server is arranged to save or record or analysis the packet event. Moreover, the predetermined server may transmit an instruction to the networking unit  504  for controlling the signal measuring and analyzing unit  508  update the firmware of the operational device  102   b . The signal measuring and analyzing unit  508  may reset or to turn-off the operational device  102   b  according to the instruction received from the predetermined server. 
     The networking unit  504  is arranged to wirelessly transmit the first detecting event Sd 1  to a processing device, i.e. the remote processing system  110 . 
     In addition, the networking unit  504  further receives data from the signal measuring and analyzing unit  508  via the SPI and the UART, wherein the SPI is arranged to receive the instant data (e.g. the state transmitted from the signal measuring and analyzing unit  508  in every 10 ms), and the UART is arranged to receive the detecting data in relatively high speed and large volume. The data received by the networking unit  504  is stored in a memory (not shown) of the networking unit  504 . Then, the networking unit  504  transmits the received data to the cloud system, i.e. the remote processing system  110 . According to some embodiments, the remote processing system  110  is arranged to update the firmware of the signal measuring and analyzing unit  508  and the operational device  102   b  through the networking unit  504 . Moreover, the remote processing system  110  is also arranged to update the firmware of the networking unit  504 . 
     According to some embodiments, the remote processing system  110  wirelessly couples to all operational devices. The remote processing system  110  updates the firmware of the monitoring device  102  and the operational device  102   b  for testing the monitoring device  102  and the operational device  102   b  under different conditions. According to some embodiments, the remote processing system  110  uses the bootloader designed inside the networking unit  504  to update the firmware of the signal measuring and analyzing unit  508  and the operational device  102   b . The remote processing system  110  may simulate the operation of the mesh network system  100  according to different number of operational devices and monitoring devices and/or different version of firmware. 
     The remote processing system  110  may be a cloud management platform for managing the operational devices  102   a ˜ 102   p  and the monitoring devices  102 ,  104 ,  106 , and  108 . For example, the remote processing system  110  is arranged to manage the registration, setting, firmware updating, information acquiring (e.g. address, id, setting of operational devices), resetting the operational devices, and setting of the pins connected to the operational devices. 
     According to some embodiments, the remote processing system  110  is arranged to acquire the occurrence time of the events and the contents of the transmitted and received packets, and to analysis the transmission paths of the packets in the mesh network system  100 . 
     In addition, the remote processing system  110  is arranged to evaluate the maximum loading of the mesh network system  100 , the maximum tolerable number of the operational devices, and the frequency of defection of an operational device. The remote processing system  110  is also arranged to determine the message storm or the abnormal operation (e.g. insufficient of memory, packet loss, or reboot unexpectedly) in the operational devices, the average processing time of a packet in an operational device, and the packet size. 
       FIG. 6  is a diagram illustrating the operation of two monitoring devices (e.g. the monitoring devices  102  and  104 ) in accordance with some embodiments. For the purpose of description, the operational device  102   b  and the operational device  102   c  are also shown in  FIG. 6 . The monitoring device  102  and the monitoring device  104  are arranged to monitor the operation of the operational device  102   b  and the operational device  102   c  respectively. The monitoring device  104  comprises a power supply unit  512 , a networking unit  514 , a time synchronization unit  516 , a signal measuring and analyzing unit  518 , and a connecting device  520 . The operational device  102   c  also comprises a GPIO pin  102   c _ 1 . 
     The power supply unit  512  is arranged to supply power to the operational device  102   c , the networking unit  514 , the time synchronization unit  516 , and the signal measuring and analyzing unit  518 . The networking unit  514  is arranged to wirelessly transmit the second detecting event Sd 2  to the remote processing system  110 . The time synchronization unit  516  is arranged to generate the clock signal Sck 2 . The signal measuring and analyzing unit  518  is coupled to the operational device  102   c  for analyzing an acknowledgement signal Sk 2  received from the operational device  102   c  to obtain the time t 4  at which the operational device  102   c  receiving the instruction signal Si. The connecting device  520  is coupled between the signal measuring and analyzing unit  518  and the operational device  102   c . The signal measuring and analyzing unit  518  further uses the second clock signal Sck 2  to lock or phase-lock the acknowledgement signal Sk 2  in order to receive the acknowledgement signal Sk 2 . As the operation of the monitoring device  104  is similar to the monitoring device  104 , the detailed description is omitted here for brevity. 
     Please refer to  FIG. 2  and  FIG. 6 , the packet  202  and the corresponding timestamp  206  are transmitted by the networking unit  504  of the monitoring device  102  at time ta and time tb respectively. When the packet  204  and the corresponding timestamp  208  are received by the networking unit  514  of the monitoring device  104  at time tc and time td respectively. The signal measuring and analyzing unit  518  is arranged to read the information of the timestamp  208  to calculate the offset between the beacon receiving time of the monitoring device  102  and the beacon receiving time of the monitoring device  104 . The offset may be transmitted to the monitoring device  102  from the monitoring device  104 . Then, the time synchronization unit  506  and the time synchronization unit  516  adjust the phases of the clock signal Sck 1  and the clock signal Sck 2 , respectively, based on the offset. Accordingly, the clock signal Sck 1  may synchronize with the clock signal Sck 2 . 
     Please refer to  FIG. 3  and  FIG. 6 , at time t 3 , when the predetermined function of the operational device  102   b  works, the instruction signal Si is transmitted from the operational device  102   b  to the operational device  102   c . Meanwhile, the acknowledgement signal Sk 1  is transmitted to the signal measuring and analyzing unit  508  via the connecting device  510 . The signal measuring and analyzing unit  508  is arranged to analyze the acknowledgement signal Sk 1  to obtain the time t 3  at which the operational device  102   b  transmitting the instruction signal Si occurs. In addition, the networking unit  504  of the monitoring device  102  is further arranged to transmit the first detecting event Sd 1  including the information of times t 1 , t 2 , and t 3  to the remote processing system  110 . 
     At time t 4 , when the instruction signal Si is received by the operational device  102   c , the acknowledgement signal Sk 2  is transmitted to the signal measuring and analyzing unit  518  via the connecting device  520 . The signal measuring and analyzing unit  518  is arranged to analyze the acknowledgement signal Sk 2  to obtain the time t 4  at which the operational device  102   c  receiving the instruction signal Si occurs. In addition, the networking unit  514  of the monitoring device  104  is further arranged to transmit the second detecting event Sd 2  including the information of times t 4 , t 5 , t 6 , and t 7  to the remote processing system  110 . 
     Accordingly, the clock signal Sck 1  may synchronize with the clock signal Sck 2  based on the offset between the beacon receiving time of the monitoring device  102  and the beacon receiving time of the monitoring device  104 . The monitoring device  102  and the monitoring device  104  may effectively monitor the operation of the operational device  102   b  and the operational device  102   c  respectively. 
     Briefly, the method of monitoring the operation of the operational device  102   b  and  102   c  may be summarized into the steps in  FIG. 7 .  FIG. 7  is a flowchart illustrating a monitoring method  700  in accordance with some embodiment. In operation  702 , arranging the operational device  102   d  to perform the predetermined function and accordingly transmitting the instruction signal Si. In operation  704 , receiving the first acknowledgement signal Sk 1  from the operational device  102   b , wherein the first acknowledgement signal Sk 1  indicates the operational device  102   b  transmitting the instruction signal Si occurs. In operation  706 , analyzing the first acknowledgement signal Sk 1  to obtain the time t 3  at which the operational device  102   b  transmitting the instruction signal Si occurs. In operation  708 , generating the first detecting event Sd 1  based on the time t 3 . In operation  710 , arranging the operational device  102   c  to receive the instruction signal Si and accordingly performing the predetermined function. In operation  712 , receiving the second acknowledgement signal Sk 2  from the operational device  102   c , wherein the second acknowledgement signal Sk 2  indicates the operational device  102   c  receiving the instruction signal Si occurs. In operation  714 , analyzing the second acknowledgement signal Sk 2  to obtain the time t 4  at which the second operational device receiving the instruction signal Si occurs. In operation  716 , generating the second detecting event Sd 2  based on time t 4 . In operation  718 , using the first detecting event Sd 1  and the second detecting event Sd 2  to determine if the first operational device  102   b  and the second operational device  102   c  functional work. 
     According to the description of the above embodiments, the number of the operational devices may be expanded to a relatively huge number in a large-scale field because the operation of the operational devices may be automatically monitored by a plurality of monitoring devices, wherein the monitoring devices are time-synchronized with each other. When the monitoring devices are time-synchronized with each other, the monitoring devices may precisely track the instruction signal transmitted in the operational devices, and accordingly determine the operation of the operational devices. 
     Please refer to  FIG. 8A , which is a schematic view showing a coordinate sensing device according to an embodiment of the present invention. The coordinate sensing device C 1  includes a transmitter C 11 , a receiver C 12  and a controller C 13 . The transmitter C 11  is configured to generate a first light signal CS 1 , a second light signal CS 2  and a third light signal CS 3 . The receiver C 12  is configured to sense the first light signal CS 1 , the second light signal CS 2  and the third light signal CS 3  for generating a receiving signal CSr. In an embodiment, the receiver C 12  uses a photodiode to sense the first light signal CS 1 , the second light signal CS 2  and the third light signal CS 3 , and convert the first light signal CS 1 , the second light signal CS 2  and the third light signal CS 3  into an electrical signal, for example, the receiving signal CSr. The controller C 13  is configured to output a coordinate of the receiver C 12  according to the receiving signal CSr. According to an embodiment of the present invention, the transmitter  12  further includes a wireless transmission module C 111 , and the receiver C 12  also further comprises a wireless transmission module C 121 . The wireless transmission module C 111  of the transmitter C 11  is configured to transmit a wireless signal CSn to the wireless transmission module C 121  of the receiver C 12 . The wireless signal CSn can be a pulse signal. According to one embodiment of the present invention, the wireless transmission modules C 111 . C 121  can be implemented using the radiofrequency (RF) technology, Bluetooth technology. ZigBee technology, Wi-Fi technology, or other wireless transmission module(s). Additionally, the controller C 13  is coupled with the transmitter C 11  and the receiver C 12 . In one embodiment, the controller C 13  is integrated within the transmitter C 11 , and the controller C 13  and the receiver C 12  are communicated through a wireless signal. In another embodiment, the controller C 13  is integrated within the receiver C 12 , and the controller C 13  and the transmitter C 11  are communicated through a wireless signal. It is also feasible to arrange the controller C 13  as a separate component, as long as it can be coupled with the transmitter C 11  and the receiver C 12  through a wired or wireless connection, and the present invention is not limited thereto. Therefore, the transmitter C 11 , the receiver C 12  and controller C 13  can be coupled to one another via a wired or wireless connection. Similarly, the connection among the transmitter C 11 , receiver C 12 , and controller C 13  can be implemented by the radiofrequency (RF) technology. Bluetooth technology, ZigBee technology. Wi-Fi technology, or other wireless transmission module(s). 
     According to one embodiment of the present invention, the controller C 13  may include a core control assembly of the coordinate sensing device C 1 ; for example, it may include at least one central processing unit (CPU, e.g., a microprocessor) and a memory, or include other control hardware(s), software(s), or firmware(s). Accordingly, it is feasible to use the controller C 13  to compute the three-dimensional coordinate or position between the object CT in a horizontal plane CP and the transmitter C 11 . 
     Please refer to  FIG. 8B , which is a schematic view illustrating the use of a coordinate sensing device C to output a coordinate of an object CT according to one embodiment of the present invention. The object CT locates in a locale, in which the locale can be an indoor warehouse space, a marketplace space, an office space, or other kinds of indoor space. The object CT can be a personnel or an article. Moreover, to determine the coordinate of the object CT, the receiver C 12  of the coordinate sensing device C 1  of the present invention can be installed on the object CT. In the relevant drawings following  FIG. 8B , the collection of the object CT and the receiver C 12  is labeled as CT/C 12 . For example, when the object CT is a personnel, the receiver C 12  can be disposed in a mobile device (such as, in a mobile phone or tablet) carried by the personnel. Moreover, the receiver C 12  can be disposed in a coordinate sensing device worn by the personnel (such as, a smart bracelet or ring worn by the personnel). Additionally, when the object CT is an article, the receiver C 12  can be disposed on the article. 
     The transmitter C 11  of the coordinate sensing device C 1  is disposed above the horizontal plane CP; that is, a horizontal level of the transmitter C 11  is higher than the horizontal level of the horizontal plane CP. For example, the transmitter C 11  can be installed on a ceiling, lighting fixture, smoke detector, air conditioner outlet, or other apparatuses in the locale. 
     According to one embodiment of the present invention, when the object CT and the receiver C 12  can move freely at any height Ch between a horizontal plane CP of the locale and the transmitter C 11 , the controller C 13  can compute the three-dimensional coordinate of the object CT in the locale. 
     According to one embodiment of the present invention, by the configuration of the transmitter C 11  and the receiver C 12 , the coordinate sensing device C 1  can compute the coordinate of the object CT at any height Ch between the horizontal plane CP and the transmitter C 11 . In other words, the coordinate is the three-dimensional coordinate in the locale. 
     According to one embodiment of the present invention, as illustrated in  FIG. 8B , the transmitter C 11  emits a first light signal CS 1 , a second light signal CS 2  and a third light signal CS 3  toward the horizontal plane CP, in which the first light signal CS 1 , the second light signal CS 2  and the third light signal CS 3  have a predetermined projection direction. In the present embodiment, the first light signal CS 1 , the second light signal CS 2  and the third light signal CS 3  respectively have a first predetermined projection direction, a second predetermined projection direction and a third predetermined projection direction, wherein the first predetermined projection direction, the second predetermined projection direction and the third predetermined projection direction are different projection directions from each other. When the first light signal CS 1 , the second light signal CS 2  and the third light signal CS 3  are projected to the horizontal plane CP of the locale according to the first predetermined projection direction, the second predetermined projection direction and the third predetermined projection direction, the surface of the horizontal plane CP will present a first straight ray pattern (straight ray pattern) CL 1 , a second straight ray pattern CL 2  and a third straight rat pattern CL 3 , respectively. It should be noted that the first straight ray pattern CL 1 , the second straight ray pattern CL 2  and the third straight ray pattern CL 3  can be an invisible pattern or visible pattern on the surface of the horizontal plane CP. According to one embodiment of the present invention, the transmitter C 11  can be a laser transmitter, which may emit three laser beams in different directions; the laser beams can be infrared (IR) laser beams, or the laser beams can be laser walls, while the first light signal CS 1 , the second light signal CS 2  and the third light signal CS 3  can be a first laser wall, a second laser wall and a third laser wall, respectively. It should be noted that the laser wall is a plane formed by beams. 
     According to the embodiment shown in  FIG. 8B , there is a predetermined angle Cθ between the laser wall of the first light signal CS 1  and the laser wall of the third light signal CS 3 , and there is another predetermined angle Cφ between the laser wall of the second light signal CS 2  and a bottom surface of the transmitter C 11 . On the horizontal plane CP, the first straight ray pattern CL 1 , the second straight ray pattern CL 2  and the third straight ray pattern CL 3  are substantially three parallel straight ray patterns, wherein the second straight ray pattern CL 2  is disposed between the first straight ray pattern CL 1  and the third straight ray pattern CL 3 . In addition, in the present embodiment, since the distance CHt between the horizontal plane CP and the transmitter C 11  and the angles Cθ and Cφ are predetermined, the respective distances between the first straight ray pattern CL, the second straight ray pattern CL 2  and the third straight ray pattern CL 3  are three predetermined distances. 
     Moreover, in the present embodiment, a bottom surface C 112  of the transmitter C 11  has a first transmitting terminal CO 1  and a second transmitting terminal CO 2 , wherein the first transmitting terminal CO 1  is configured to output the first light signal CS 1  and the third light signal CS 3 , the second transmitting terminal CO 2  is configured to output the second light signal CS 2 , and the distance between the first transmitting terminal CO 1  and the second transmitting terminal CO 2  is a predetermined distance. In the present embodiment, the bottom surface C 112  faces the horizontal plane CP, and the bottom surface C 112  is parallel to the horizontal plane CP. 
     It should be noted that in another embodiment of the present invention, the first light signal CS 1  and the third light signal CS 3  also may have the same projection direction. For example, the first light signal CS 1  is substantially parallel to the third light signal CS 3  as shown in  FIG. 8C  which is a schematic view illustrating a coordinate of the object CT computed by the coordinate sensing device C 1   a  of the present invention. As shown in  FIG. 8C , the transmitter C 11   a  may emit three infrared laser beams S 1   a , S 1   b  and S 1   c , wherein the first infrared laser beam S 1   a  is substantially parallel to the third infrared laser beam S 1   c , and the second infrared laser beam S 1   b  is not parallel to the infrared laser beams S 1   a , S 1   b . In the present embodiment, there is a predetermined angle Cφ between the laser wall of the second infrared laser beam S 1   b  and a bottom surface C 112   a  of the transmitter C 11   a . Accordingly, the present invention is not limited to any particular aspect of the lights emitted by the transmitter C 11   a . As long as the respective predetermined angles between the infrared laser beams S 1   a , S 1   b . S 1   c  and the bottom surface C 112   a  of the transmitter C 11   a  and the distance between the transmitter C 11   a  and the horizontal plane CP (i.e., the height in the z-axis) are known, it is still feasible to compute the distances between the first straight ray pattern CL 1 , the second straight ray pattern CL 2  and the third straight ray pattern CL 3  on the horizontal plane CP. 
       FIG. 8D  is a schematic view illustrating the use of a coordinate sensing device C of the present invention to output a coordinate of an object CT according to another embodiment. The embodiment shown in  FIG. 8D  is the same as the embodiment shown in  FIG. 8B . As shown in  FIG. 8D , the transmitter C 11  emits the first light signal CS 1 , the second light signal CS 2  and the third light signal CS 3  toward the horizontal plane CP. The first light signal CS 1 , the second light signal CS 2  and the third light signal CS 3  form a first laser wall CS 11 , a second laser wall CS 22  and a third laser wall CS 33  between the transmitter C 11  and the horizontal plane CP, respectively. The first laser wall CS 11 , the second laser wall S 12  and the third laser wall S 13  are three triangle planes shown in  FIG. 8D , respectively. In addition, the first light signal CS 1  and the third light signal CS 3  are output from the first transmitting terminal CO 1 , and the second light signal CS 2  is output from the second transmitting terminal CO 2 . When the first light signal CS 1 , the second light signal CS 2  and the third light signal CS 3  reach the horizontal plane CP, three parallel straight ray patterns are formed on the horizontal plane CP (that is the first straight ray pattern CL, the second straight ray pattern CL 2  and the third straight ray pattern CL 3 ). According to one embodiment of the present embodiment, a point on the horizontal plane CP that is right below the transmitter C 11  is defined as a rotation center CO. 
     Please refer to  FIG. 8E , which is schematic view illustrating the use of a coordinate sensing device C 1  of the present invention to output a coordinate of an object CT according to another embodiment. As illustrated in  FIG. 8E , during the operation of the coordinate sensing device C 1 , the transmitter C 11  controls the first light signal CS 1 , the second light signal CS 2  and the third light signal CS 3  such that the first straight ray pattern CL 1 , the second straight ray pattern CL 2  and the third straight ray pattern CL 3  rotate about the rotation center CO. In the present embodiment, the rotation direction is clockwise; however, the present invention is not limited thereto. In another embodiment, the rotation direction can also be counterclockwise. In one embodiment, the transmitter C 11  controls the first light signal CS 1 , the second light signal CS 2  and the third light signal CS 3  through a control unit (not shown in the drawings) such that the first straight ray pattern CL 1 . the second straight ray pattern CL 2  and the third straight ray pattern CL 3  rotate about the rotation center CO simultaneously, and therefore, the first laser wall CS 11 , the second laser wall CS 22  and the third laser wall CS 33  sequentially scan over (or pass through) the receiver C 12  on the object CT. It should be noted that the rotation center CO of the present invention is not limited to the one on the horizontal plane CP right below the transmitter C 11 . In some other embodiments, the transmitter C 11  itself also rotates in a different direction such that the rotation center CO on the horizontal plane CP also rotates simultaneously. Alternatively, in some other embodiments, the transmitter C 11  itself does not rotate, and only the first straight ray pattern CL 1 , the second straight ray pattern CL 2  and the third straight ray pattern CL 3  rotate about the rotation center CO simultaneously. 
     When the first straight ray pattern CL 1 , the second straight ray pattern CL 2  and the third straight ray pattern CL 3  rotate about the rotation center CO, the first laser wall CS 11 , the second laser wall CS 22  and the third laser wall CS 33  scan over the receiver C 12  on the object CT at different time points. When the first laser wall CS 11  scan over the object CT, the receiver C 12  on the object CT senses the light from the first laser wall CS 11 , and accordingly, the receiver C 12  outputs a first signal at a first time point. When the second laser wall CS 22  scan over the object CT, the receiver C 12  on the object CT senses the light from the second laser wall CS 22 , and accordingly, the receiver C 12  outputs a second signal at a second time point. When the third laser wall CS 33  scan over the object CT, the receiver C 12  on the object CT senses the light from the third laser wall CS 22 , and accordingly, the receiver C 12  outputs a third signal at a third time point. According to one embodiment of the present invention, the first signal, the second signal and the third signal are a first pulse signal, a second pulse signal and a third pulse signal, respectively. 
       FIG. 8F  is a top view illustrating the use of a coordinate sensing device C 1  of the present invention to scan an object CT according to another embodiment. For simplicity,  FIG. 8F  only shows the first straight ray pattern CL 1  and the third straight ray pattern CL 3 , and their first laser wall CS 11  and the third laser wall CS 33 , respectively. In  FIG. 8F , the rotation center CO is superimposed on the first transmitting terminal CO 1 , and is indicated as CO/CO 1 . The height Ch of the object CT is between the horizontal plane CP and the transmitting terminal CO 1  When the first ray pattern CL 1  and the third ray pattern CL 3  rotate about the rotation center CO on the horizontal plane CP by 360 degrees, the four positions CA, CB, CC, CD on the first laser wall CS 11  and the third laser wall CS 33  sequentially scan over the receiver C 12  on the object CT. The receiver C 12  outputs four pulse signals at four corresponding time points, respectively, as illustrated in  FIG. 8G .  FIG. 8G  is an oscillogram of a receiving signal CSr generated by a receiver C 12  according to one embodiment of the present invention. The receiving signals Sr at the time points Ct 1 , Ct 3 , Ct 4 , Ct 6  are four pulse signals CSp 1 , CSp 2 , CSp 3 , CSp 4 , respectively. According to one embodiment of the present invention, the pulse signals CSp 1 , CSp 2  are corresponding to the positions CA, CB of the first laser wall CS 11  and the third laser wall CS 33 , respectively, and the pulse signals CSp 3 , CSp 4  are corresponding to the positions CC, CD of the third laser wall CS 33  and the first laser wall CS 11 , respectively. Further, if the period of a full cycle of scanning of the first straight ray pattern CL 1  and the third straight ray pattern CL 3  is CTP, then the time difference between the respective central time points Ct 1 , Ct 4  of the pulse signals CSp 1 , CSp 3  or the time difference between the respective central time points Ct 3 . Ct 6  of the pulse signals CSp 2 , CSp 4  is half the scan period (CTP/2). The angular velocity ω at which the first straight ray pattern CL and the third straight ray pattern CL 3  rotate on the horizontal plane CP can be calculated from formula (1): 
       ω=2π/CTP  (1)
 
     Accordingly, the angular velocity ω at which the first straight ray pattern CL 1  and the third straight ray pattern CL 3  rotate on the horizontal plane CP is a predetermined angular velocity. It should be noted that the angular velocity of the first laser wall CS 11  and the third laser wall CS 33  at the height Ch is the same as the angular velocity ω of the first straight ray pattern CL 1  and the third straight ray pattern CL 3  on the horizontal plane CP. 
     It should be noted that in order to avoid the issue that the noise light in the ambient environment might affect the accuracy of the receiver C 12 , in some embodiments, the coordinate sensing device C 1 ,  1   a  can further comprise a filter (not shown in the drawings) disposed on the receiver C 12 , and the filter is configured to allow only the passage of the first light signal CS 1 , the second light signal CS 2  and the third light signal CS 3 . By using the filter, it is possible to filter out the light other than the first light signal CS 1 , the second light signal CS 2  and the third light signal CS 3 , thereby improving the detection accuracy of the receiver C 12 . 
     Please refer to  FIG. 8H , which is a top view illustrating the use of a coordinate sensing device C 1  to scan an object CT according to another embodiment of the present invention. As shown in  FIG. 8H , when the first straight ray pattern CL 1 , the second straight ray pattern CL 2  and the third straight ray pattern CL 3  continue to rotate about the rotation center CO on the horizontal plane CP, the first laser wall CS 11 , the second laser wall CS 22  and the third laser wall CS 33  sequentially scan over the receiver C 12  on the object CT. The receiver C 12  can sense light from the first laser wall CS 11 , the second laser wall CS 22  and the third laser wall CS 33  for multiple times at different time points. Therefore, the receiving signal CSr generated by the receiver C 12  has multiple sets of pulse signals. 
     Moreover, in the present embodiment, when the first laser wall CS 11 , the second laser wall CS 22  and the third laser wall CS 33  scan over the object CT, the transmitter C 11  first uses the wireless transmission module C 111  depicted in  FIG. 8A  to transmit a wireless signal CSn to the wireless transmission module C 121  of the receiver C 12 . When the receiver C 12  receives the wireless signal CSn, the receiver C 12  generates a reference time Ct 0 . The reference time Ct 0  is configured to synchronize the transmitter C 11  and the receiver C 12 , and therefore, the wireless signal CSn can be viewed as a synchronizing signal. Furthermore, the transmitter C 11  transmits the wireless signal CSn to the receiver C 12  when the first straight ray pattern CL 1 , or the third straight ray pattern CL 3  has a predetermined angle or a reference angle (such as, 0 degree), such that the receiver C 12  generates a reference time (i.e., Ct 0 ). Next, whenever the first straight ray pattern CL 1  or the third straight ray pattern CL 3  rotates to the predetermined angle or the reference angle, the transmitter C 11  transmits the wireless signal CSn to the receiver C 12 , such that the receiver C 12  generates a reference time (i.e., Ct 0 ). In this way, the transmitter C 11  and the receiver C 12  are synchronized.  FIG. 8I  is an oscillogram of a receiving signal CSr generated by a receiver C 12  according to another embodiment of the present invention. The receiving signals Sr, at the time points Ct 1 , Ct 2 , Ct 3 , are three pulse signals CSp 1 , CSp 2 , CSp 3 , respectively; the pulse signals CSp 1 , CSp 2 , CSp 3  correspond to the positions of the object CT scanned by the first laser wall CS 11 , the second laser wall CS 22  and the third laser wall CS 33 , respectively. According to one embodiment of the present invention, the receiver C 12  receives the wireless signal CSn from the transmitter C 11  at the reference time Ct 0 . Further, the receiving signal CSr generated by the receiver C 12  is received and stored by the controller C 13 . 
     Moreover, there is a time interval (or time difference) CT d1  between the first time Ct 1  and the second time Ct 2 , and the time interval CT d1  is the time difference between the central time points of the pulse signals CSp 1 , CSp 2 ; that is. CT d1 =Ct 2 −Ct 1 . There is a time interval (or time difference) CT d2  between the second time Ct 2  and the third time Ct 3 , and the time interval CT d2  is the time difference between the central time points of the pulse signals CSp 2 , CSp 3 ; that is, CT d2 =Ct 3 −Ct 2 . 
     It should be noted that, when implementing this embodiment, a microprocessor within the controller C 13  can record the time points of the rising and falling edges of three consecutive pulse signals (CS 1 , CS 2  and CS 3 ) so that it can further compute the central time points of the two pulse signals, thereby obtaining a more accurate time difference. 
     Moreover, a mean value of the first time Ct 1  and the third time Ct 3  can be calculated; the mean value is (Ct 1 +Ct 3 )/2. A time difference between the mean value and the reference time Ct 0  is (Ct 1 +Ct 3 )/2−Ct 0 ; i.e. the time required for the first laser wall CS 11  or the third laser wall CS 33  to rotate from the reference angle to the receiver C 12  of the object CT. Furthermore, a rotation angle ψ can be calculated by multiplying the time difference between the mean value (i.e., (Ct 1 +Ct 3 )/2) and the reference time Ct 0  by the angular velocity ω, referring to the following formula (2): 
       Ψ=ω*(( Ct 1+ Ct 3)/2− Ct 0)  (2)
 
     Generally, the rotation angle ψ is the angle of the first laser wall CS 11  or the third laser wall CS 33  rotating from a reference point to the object CT. According to one embodiment of the present invention, the controller C 13  uses the above-mentioned rotation angle ψ to compute the three-dimensional coordinate of the object CT at the height Ch. 
       FIG. 8J  is a top view illustrating the use of the coordinate sensing device C 1  of the present invention to compute the three-dimensional coordinate according to one embodiment. In  FIG. 8J , the vertical height of the object CT (or the receiver C 12 ) from the horizontal plane CP is h. In addition, on a horizontal line C 301  of the height Ch, the second laser wall CS 22  is formed between the first laser wall CS 11  and the third laser wall CS 33 . A normal line CN perpendicular to the horizontal plane CP and passing through the rotation center CO is aligned with the first transmitting terminal CO 1  of the bottom surface C 112  of the transmitter C 11 , i.e. the normal line CN passing through the first transmitting terminal CO 1 . The second laser wall CS 22  is emitted from the second transmitting terminal CO 2 , and the second transmitting terminal CO 2  is offset from the normal line CN. Further, the three laser walls CS 11 , CS 22 . CS 33  rotate about the rotation center CO at the angular velocity ω(ω=2π/CTP). The vertical or the shortest distance between the transmitter C 11  and the horizontal plane CP is CHt. Similar to  FIG. 8B , there is an angle Cθ between the first laser wall CS 11  and the third laser wall CS 33 , which is a predetermined angle. There is a predetermined distance CRd between the first transmitting terminal CO 1  and the second transmitting terminal CO 2  of the bottom surface C 112  of the transmitter C 11 , and there is an angle Cφ between the second laser wall CS 22  and the bottom surface C 112 , which is a predetermined angle. 
     Additionally, on the horizontal line C 301  of the height Ch, the first laser light wall CS 11  intersects the horizontal line C 301  at the point Ca, the second laser wall CS 22  intersects the horizontal line C 301  at the point Cb, the third laser wall CS 33  intersects the horizontal line C 301  at the point Cc, and the normal line CN intersects the horizontal line C 301  at the point Cd. On the horizontal line C 301 , the straight line distance between the point Cd and the point Cc is Cd a , the straight line distance between the point Cb and the point Cd is Cd b , and the straight line distance between the point Ca and the point Cd is Cd c . It should be noted that these straight line distances Cd a , Cd b , Cd c  will change along with the variation of the height Ch of the object CT. 
     Please refer to  FIG. 8K , which is a top view illustrating the use the coordinate sensing device C 1  to scan an object CT according to one embodiment of the present invention. As illustrated in  FIG. 8K , in the present embodiment, there is a distance Cr between the normal line CN passing through the rotation center CO and the object CT, when viewed from the top, and the position at which the first laser wall CS 11  rotates and passes through the object CT is a first point position CP 1 . Meanwhile, for the second laser wall CS 22 , there is a second point position CP 2  that is spaced from the normal line CN passing through the rotation center CO by the same distance Cr; and for the third laser wall CS 33 , there is a third point position CP 3  that is spaced from the normal line CN passing through the rotation center CO by the same distance Cr. In this case, the first point position CP 1  and the normal line CN form a first straight line C 302 , the second point position CP 2  and the normal line CN form a second straight line C 304 , the third point position CP 3  and the normal line CN form a third straight line C 306 , and there is a fourth straight line C 308  in the middle between the first laser wall CS 11  and the third laser wall CS 33 . The fourth straight line C 308  is parallel to the first laser wall CS 11  or the third laser wall CS 33 . The first straight line C 302  and the third straight line C 306  have an included angle CΦ therebetween, the first straight line C 302  and the fourth straight line C 308  have an included angle Cα therebetween, the fourth straight line C 308  and the second straight line C 304  have an included angle CP therebetween, and the second straight line C 304  and the third straight line C 306  have an included angle Cγ therebetween. In the present embodiment, the included angle CΦ is equal to the sum of the included angles Cα, Cβ and Cγ. In addition, the included angle Cα is substantially a half of the included angle CΦ. Since the first straight ray pattern CL 1  and the second straight ray pattern CL 2  have the predetermined angular velocity ω when they rotate about the rotation center CO, the above-mentioned included angle Cα would equal to the product of the predetermined angular velocity ω multiplying the mean value of the first time interval CT d1  and the second time interval CT d2 , referring to the following formula (3): 
         C α=ω*( CT   d1   +CT   d2 )/2  (3)
 
     In addition, at the height Ch, there is a distance CS between the first laser wall CS 11  and the third laser wall CS 33  (the distance CS changes along with the variation of the height Ch in the present embodiment). 
     As illustrated in  FIG. 8J  and  FIG. 8K , the first straight line distance Cd a  is equal to the third straight line distance Cd c , referring to the following formula (4): 
         Cd   c   =Cd   a =( CHt−Ch )*tan( Cθ/ 2)  (4)
 
     The second straight line distance Cd b  satisfies the following formula (5): 
         Cd   b =( CHt−Ch )* cot ( C φ)− CRd   (5)
 
     Further, the following formulas (6), (7), (8), (9) and (10) can be derived from  FIG. 8J  and  FIG. 8K : 
       sin  Cα=CS/ 2 Cr=Cd   c   /Cr   (6)
 
       Sin  Cβ=Cd   b   /Cr   (7)
 
         Cγ=Cα−Cβ   (8)
 
         CT   d1 =( Cα+C β)/ω  (9)
 
         CT   d2 =( Cα−C β)/ω  (10)
 
     According to the above formulas, the controller C 13  can compute the values of the straight line distance Cr and the height Ch in light of the following formulas (11) and (12): 
     
       
         
           
             
               
                 
                   
                       
                   
                    
                   
                     
                       Cd 
                       c 
                     
                     = 
                     
                       Cr 
                       * 
                       
                         sin 
                         ( 
                         
                           
                             ω 
                             * 
                             
                               ( 
                               
                                 
                                   
                                     CT 
                                     
                                       d 
                                        
                                       
                                           
                                       
                                        
                                       1 
                                     
                                   
                                   + 
                                   
                                     CT 
                                     
                                       d 
                                        
                                       
                                           
                                       
                                        
                                       2 
                                     
                                   
                                 
                                 2 
                               
                               ) 
                             
                           
                           = 
                           
                             
                               ( 
                               
                                 CHt 
                                 - 
                                 Ch 
                               
                               ) 
                             
                             * 
                             
                               tan 
                                
                               
                                 ( 
                                 
                                   
                                     C 
                                      
                                     
                                         
                                     
                                      
                                     θ 
                                   
                                   2 
                                 
                                 ) 
                               
                             
                           
                         
                       
                     
                   
                 
               
               
                 
                   ( 
                   11 
                   ) 
                 
               
             
             
               
                 
                   
                     Cd 
                     b 
                   
                   = 
                   
                     Cr 
                     * 
                     
                       sin 
                       ( 
                       
                         
                           ω 
                           * 
                           
                             ( 
                             
                               
                                 
                                   CT 
                                   
                                     d 
                                      
                                     
                                         
                                     
                                      
                                     1 
                                   
                                 
                                 + 
                                 
                                   CT 
                                   
                                     d 
                                      
                                     
                                         
                                     
                                      
                                     2 
                                   
                                 
                               
                               2 
                             
                             ) 
                           
                         
                         = 
                         
                           
                             
                               ( 
                               
                                 CHt 
                                 - 
                                 Ch 
                               
                               ) 
                             
                             * 
                             
                               cot 
                                
                               
                                 ( 
                                 
                                   C 
                                    
                                   
                                       
                                   
                                    
                                   ϕ 
                                 
                                 ) 
                               
                             
                           
                           - 
                           
                             CR 
                             d 
                           
                         
                       
                     
                   
                 
               
               
                 
                   ( 
                   12 
                   ) 
                 
               
             
           
         
       
     
     The angular velocity ω, the first time interval CT d1  and the second time interval CT d2  can be obtained from measurement and computation. The height CHt (i.e., the distance between the transmitter C 11  and the horizontal plane CP), the included angle Cθ, the included angle Cφ and the predetermined distance CRd are known parameters. Therefore the height Ch of the object CT and the distance Cr can be computed by the controller C 13  according to the above formulas (11) and (12), and are combined with the rotation angle Ψ obtained from the above formula (2), thereby obtaining the three-dimensional coordinate (x,y,z) of the object CT in the locale, illustrated in the following formula: 
         x=Cr *cos(ψ), y=Cr *sin(ψ), z=Ch   (13)
 
     x represents an x-coordinate distance of the object CT at the height Ch, y represents a y-coordinate distance of the object CT at the height Ch, z represents a height of the object CT spaced from the horizontal plane CP, and Ψ represents the rotation angle. 
     Based on the above illustrations, the three-dimensional coordinate (x,y,z) of the object CT in the locale can be computed by the microprocessor in the controller C 13  according to the angular velocity ω at which the first light signal CS 1 , the second light signal CS 2  and the third light signal CS 3  rotate (or the angular velocity ω at which the first laser wall CS 11 , the second laser wall CS 22  and the third laser wall CS 33  rotate), the distance between the transmitter C 11  and the horizontal plane CP (i.e., CHt), the first time interval CT d1 , the second time interval CT d2  and the reference time Ct 0 . Accordingly, the exact position of an object CT in a specific locale can be accurately obtained by the embodiment of the present invention. 
     Referring to  FIG. 9A , which is a schematic view illustrating a coordinate sensing device B 1  according to one embodiment of the present invention. The coordinate sensing device B 1  comprises a transmitter B 11 , a receiver B 12 , and a controller B 13 . The transmitter B 11  is configured to generate a first light signal BS 1  and a second light signal BS 2 . The receiver B 12  is configured to sense the first light signal BS 1  and the second light signal BS 2 , so as to generate a receiving signal BSr. In one embodiment, the receiver B 12  uses a photodiode to detect the first light signal BS 1  and the second light signal BS 2 , and convert the first light signal BS 1  and the second light signal BS 2  into an electric signal, such as the receiving signal BSr. The controller B 13  is configured to output a coordinate of the receiver B 12  according to the receiving signal BSr. According to one embodiment of the present invention, the transmitter B 11  further comprises a wireless transmission module B 111 , whereas the receiver B 12  also further comprises a wireless transmission module B 121 . The wireless transmission module B 111  of the transmitter B 11  is configured to transmit a wireless signal BSn to the wireless transmission module B 121  of the receiver B 12 . The wireless signal BSn can be a pulse signal. According to one embodiment of the present invention, the wireless transmission modules B 111 , B 121  can be implemented using the radiofrequency (RF) technology, Bluetooth technology, ZigBee technology, Wi-Fi technology, or other wireless transmission module(s). Additionally, the controller B 13  is coupled with the transmitter B 11  and the receiver B 12 . In one embodiment, the controller B 13  is integrated within the transmitter B 11 , whereas the controller B 13  and the receiver B 12  are communicated through a wireless signal. In another embodiment, the controller B 13  is integrated within the receiver B 12 , whereas the controller B 13  and the transmitter B 11  are communicated through a wireless signal. It is also feasible to arrange the controller B 13  as a separate member, as long as it can be coupled with the transmitter B 11  and the receiver B 12  through a wired or wireless connection, and the present invention is not limited thereto. Therefore, the transmitter B 11 , the receiver B 12  and controller B 13  can be coupled to one another via a wired or wireless connection. Similarly, the connection among the transmitter B 11 , receiver B 12 , and controller B 13  can be implemented by the radiofrequency (RF) technology, Bluetooth technology, ZigBee technology, Wi-Fi technology, or other wireless transmission module(s). 
     According to one embodiment of the present invention, the controller B 13  may comprise a core control assembly of the coordinate sensing device B 1 ; for example, it may comprise at least one central processing unit (CPU, e.g., a microprocessor) and a memory, or comprises other control hardware(s), software(s), or firmware(s). Accordingly, it is feasible to use the controller B 13  to compute the two-dimensional or three-dimensional position of the object BT in a horizontal plane BP. 
     Referring to  FIG. 9B , which is a schematic view illustrating the use of a coordinate sensing device B 1  of the present invention to output a coordinate of an object BT according to one embodiment. The object BT locates in a locale, in which the locale can be an indoor warehouse space, a marketplace space, an office space, or other kinds of indoor space. The object BT can be a personnel or an article. Moreover, to determine the coordinate of the object BT, the receiver B 12  of the present coordinate sensing device B 1  can be installed on the object BT. In the relevant drawings following  FIG. 9B , the collection of the object BT and the receiver B 12  is labeled as BT/B 12 . For example, when the object BT is a personnel, the receiver B 12  can be disposed in a mobile device (such as, in a mobile phone or tablet) carried by the personnel. Moreover, the receiver B 12  can be disposed in a coordinate sensing device worn by the personnel (such as, a smart bracelet or ring worn by the personnel). Additionally, when the object BT is an article, the receiver B 12  can be disposed on the article. 
     According to one embodiment of the present invention, the object BT and the receiver B 12  can move freely in a horizontal plane BP of the locale; for example, the horizontal plane BP can be the ground of the locale. For simplicity and brevity, the object BT and the receiver B 12  locate at a horizontal level that is substantially the same as the horizontal level of the horizontal plane BP. In other words, the object BT and the receiver B 12  is in contact with a surface of the horizontal plane BP. However, the present invention is not limited thereto. In practical applications, the object BT and the receiver B 12  are higher than the horizontal plane BP; nonetheless, this would not affect the operation of the present coordinate sensing device B 1 , and the present coordinate sensing device B 1  can still output the coordinate of the object BT in the horizontal plane BP. 
     Moreover, the transmitter B 11  of the coordinate sensing device B 1  is disposed above the horizontal plane BP; that is, a horizontal level of the transmitter B 11  is higher than the horizontal level of the horizontal plane BP. For example, the transmitter B 11  can be installed on a ceiling, lighting fixture, smoke detector, air conditioner outlet, or other apparatuses in the locale. 
     According to one embodiment of the present invention, by disposing the transmitter B 11  in combination with the receiver B 12 , the coordinate sensing device B 1  can output any coordinate of the object BT in the horizontal plane BP in relative to the transmitter B 11 . In other words, the coordinate can be a two-dimensional coordinate or three-dimensional coordinate in the locale. However, for the sake of simplicity and brevity, the present embodiment is primarily directed to the operation of a coordinate sensing device B 1  that outputs the two-dimensional coordinate of the object BT in the horizontal plane BP; that is, the respective distances in the x-axis and y-axis of the horizontal plane BP. 
     According to one embodiment of the present invention, as illustrated in  FIG. 9B , the transmitter B 11  emits a first light signal BS 1  and a second light signal BS 2  toward the horizontal plane BP, in which the first light signal BS 1  and the second light signal BS 2  have a pre-determined projection direction. In the present embodiment, the first light signal BS 1  and the second light signal BS 2  have the same projection direction. For example, the first light signal BS 1  is substantially parallel to the second light signal BS 2 . When the first light signal BS 1  and the second light signal BS 2  are projected to the horizontal plane BP of the locale, the surface of the horizontal plane BP will present a first straight ray pattern (straight ray pattern) BL 1  and a second straight ray pattern BL 2 , respectively. It should be noted that the first straight ray pattern BL 1  and the second straight ray pattern BL 2  can be an invisible pattern or visible pattern on the surface of the horizontal plane BP. According to one embodiment of the present invention, the transmitter B 11  can be a laser transmitter, which may emit two parallel laser beams; the laser beam can be an infrared (IR) laser beam, or the laser beam can be a laser wall, while the first light signal BS 1  and the second light signal BS 2  can be a first laser wall and a second laser wall, respectively. It should be noted that the laser wall is a plane formed by beams. Since the laser wall of the first light signal BS 1  is parallel to the laser wall of the second light signal BS 2 , the first straight ray pattern BL 1  and the second straight ray pattern BL 2  respectively formed by the first light signal BS 1  and the second light signal BS 2  in the horizontal plane BP are also two straight ray patterns that are parallel to each other, in which the distance or spacing between the first straight ray pattern BL 1  and the second straight ray pattern BL 2  has a fixed value, which is the so-called “pre-determined spacing”. 
     It should be noted that in another embodiment of the present invention, the first light signal BS 1  and the second light signal BS 2  may have different projection directions; for example, the respective projection directions of the first light signal BS 1  and the second light signal BS 2  form a pre-determined included angle, as illustrated in  FIG. 9C , which is a schematic view illustrating the use of the coordinate sensing device B 1   a  of the present invention to output a coordinate of an object BT according to another embodiment. As illustrated in  FIG. 9C , the transmitter B 11   a  can emit two non-parallel infrared laser beams BS 1   a , BS 1   b , wherein a pre-determined included angle Bβ is formed between the respective laser walls of the infrared laser beams BS 1   a , BS 1   b . Similarly, the infrared laser beams BS 1   a , BS 1   b  can also form two parallel patterns (i.e., the first straight ray pattern BL 1  and the second straight ray pattern BL 2 ) in the horizontal plane BP. Accordingly, the present invention is not limited to any particular aspect of the lights emitted by the transmitter B 11   a . As long as the pre-determined included angle Bβ between the infrared laser beams BS 1   a , BS 1   b  and distance between the transmitter B 11   a  and horizontal plane BP (i.e., the height in the z-axis) are known, it is still feasible to compute the spacing between the first straight ray pattern BL 1  and the second straight ray pattern BL 2  in the horizontal plane BP. Moreover, when the object BT and the receiver B 12  locate above the horizontal plane BP; that is, the horizontal level of the object BT and the receiver B 12  is higher than the horizontal level of the horizontal plane BP, then, as long as the pre-determined included angle Bβ between the infrared laser beams BS 1   a , BS 1   b  and the distance between the transmitter B 11  and the receiver B 12  (i.e., the object BT) are known, it is also feasible to compute the spacing between the first straight ray pattern BL 1  and the second straight ray pattern BL 2  at the horizontal level of the receiver B 12 . 
       FIG. 9D  is a schematic view illustrating the use of a coordinate sensing device B 1  of the present invention to output a coordinate of an object BT according to another embodiment. As illustrated in  FIG. 9D , the transmitter B 11  emits two parallel laser walls toward the horizontal plane BP, i.e., the first light signal BS 1  and the second light signal BS 2 . When the two parallel laser walls reach the horizontal plane BP, two parallel straight ray patterns (that is the first straight ray pattern BL 1  and the second straight ray pattern BL 2 ) are formed in the horizontal plane BP. According to one embodiment of the present invention, a point in the horizontal plane BP that is right below the transmitter B 11  is defined as a rotation center BO. 
       FIG. 9E  is schematic view illustrating the use of a coordinate sensing device B 1  of the present invention to output a coordinate of an object BT according to another embodiment. As illustrated in  FIG. 9E , during the operation of the coordinate sensing device B 1 , the transmitter B 11  controls the first light signal BS 1  and the second light signal BS 2  such that the first straight ray pattern BL 1  and the second straight ray pattern BL 2  rotate about the rotation center BO. In the present embodiment, the rotation direction is clockwise; however, the present invention is not limited thereto. In another embodiment, the rotation direction can also be counterclockwise. In one embodiment, the transmitter B 11  controls the first light signal BS 1  and the second light signal BS 2  through a control unit (not shown in the drawings) such that the first straight ray pattern BL 1  and the second straight ray pattern BL 2  rotate about the rotation center BO simultaneously, and therefore, the lights forming the first straight ray pattern BL 1  and the second straight ray pattern BL 2  sequentially scan over (or pass through) the receiver B 12  on the object BT. It should be noted that the rotation center BO of the present invention is not limited to the one on the horizontal plane BP right below the transmitter B 11 . In some other embodiments, the transmitter B 11  itself also rotates in a different direction such that the rotation center BO on the horizontal plane BP also rotates simultaneously. Alternatively, in some other embodiments, the transmitter B 11  itself does not rotate, and there are only the first straight ray pattern BL 1  and the second straight ray pattern BL 2  that rotate about the rotation center BO simultaneously. 
     When the first straight ray pattern BL 1  and the second straight ray pattern BL 2  rotate about the rotation center BO, the first straight ray pattern BL 1 , and the second straight ray pattern BL 2  scan over the receiver B 12  on the object BT at different time points. When the first straight ray pattern BL 1  scan over the object BT, the receiver B 12  on the object BT senses the light from the first straight ray pattern BL 1 , and accordingly, the receiver B 12  outputs a first signal at a first time point. When the second straight ray pattern BL 2  scan over the object BT, the receiver B 12  on the object BT senses the light from the second straight ray pattern BL 2 , and accordingly, the receiver B 12  outputs a second signal at a second time point. According to one embodiment of the present invention, the first signal and the second signal are respectively a first pulse signal and a second pulse signal. 
       FIG. 9F  is a top view illustrating the use of a coordinate sensing device B 1  of the present invention to scan an object BT according to another embodiment. When the first straight ray pattern BL 1  and the second straight ray pattern BL 2  rotate around the rotation center BO in the horizontal plane BP by 360 degrees, the four positions BA, BB, BC, BD on the first straight ray pattern BL 1  and the second straight ray pattern BL 2  sequentially scan over the receiver B 12  on the object BT. The receiver B 12  outputs four pulse signals at four corresponding time points, respectively, as illustrated in  FIG. 9G .  FIG. 9G  is an oscillogram of a receiving signal BSr generated by a present receiver B 12  according to one embodiment. The receiving signals BSr at the time points Bt 1 , Bt 2 , Bt 3 , Bt 4  are four pulse signals BSp 1 , BSp 2 , BSp 3 , BSp 4 , respectively. According to one embodiment of the present invention, the pulse signals BSp 1  and BSp 2  correspond to the position BA of the first straight ray pattern BL 1  and the position BB of the second straight ray pattern BL 2 , respectively; while the pulse signals BSp 3  and BSp 4  correspond to the position BC of the first straight ray pattern BL 1  and the position BD of the second straight ray pattern BL 2 , respectively. Further, when the period of a full cycle of scanning of the first straight ray pattern BL 1  and the second straight ray pattern BL 2  is BTP, then the time difference between the respective central time points Bt 1 , Bt 3  of the pulse signals BSp 1 , BSp 3  or the time difference between the respective central time points Bt 2 , Bt 4  of the pulse signals BSp 2 , BSp 4  is half the scan period (BTP/2). The angular velocity to at which the first straight ray pattern BL 1  and the second straight ray pattern BL 2  rotate in the horizontal plane BP can be calculated from equation (1): 
       ω=2π/ BTP   (1)
 
     Accordingly, the angular velocity co at which the first straight ray pattern BL 1  and the second straight ray pattern BL 2  rotate in the horizontal plane BP is a pre-determined angular velocity. 
     It should be noted that in order to avoid the issue that the noise light in the ambient environment might affect the accuracy of the receiver B 12 , in some embodiments, the coordinate sensing device B 1 , B 1   a  can further comprise a filter (not shown in the drawings) disposed on the receiver B 12 , the filter is configured to allow only the passage of the first straight ray pattern BL 1  and the second straight ray pattern BL 2 . By using the filter, it is possible to filter out the light other than the first straight ray pattern BL 1  and the second straight ray pattern BL 2 , thereby improving the detection accuracy of the receiver B 12 . 
       FIG. 9H  is a top view illustrating the use of a coordinate sensing device B 1  of the present invention to scan an object BT according to another embodiment. As can be seen in  FIG. 9H , when the first straight ray pattern BL 1  and the second straight ray pattern BL 2  continue to rotate in the horizontal plane BP about the rotation center BO, the first straight ray pattern BL 1  and the second straight ray pattern BL 2  sequentially scan over the receiver B 12  on the object BT. The receiver B 12  can sense the first straight ray pattern BL 1  and the second straight ray pattern BL 2  for multiple times at different time points. Therefore, the receiving signals BSr generated by the receiver B 12  will have multiple sets of pulse signals. 
     Moreover, in the present embodiment, when the first straight ray pattern BL 1  and the second straight ray pattern BL 2  scan over the object BT, the transmitter B 11  first uses the wireless transmission module B 111  depicted in  FIG. 9A  to transmit a wireless signal BSn to the wireless transmission module B 121  of the receiver B 12 . When the receiver B 12  receives the wireless signal BSn, the receiver B 12  generates a reference time Bt 0 . The reference time Bt 0  is configured to synchronize the transmitter B 11  and the receiver B 12 , and therefore, the wireless signal BSn can be viewed as a synchronizing signal. Furthermore, the transmitter B 11  transmits the wireless signal BSn to the receiver B 12  when the first straight ray pattern BL 1  or the second straight ray pattern BL 2  has a pre-determined angle or a reference angle (such as, 0 degree), such that the receiver B 12  generates a reference time (i.e., Bt 0 ). Next, whenever the first straight ray pattern BL 1  or the second straight ray pattern BL 2  rotates to said pre-determined angle or the reference angle, the transmitter B 11  transmits the wireless signal BSn to the receiver B 12 , such that the receiver B 12  generates a reference time (i.e., Bt 0 ). In this way, the transmitter B 11  and the receiver B 12  are synchronized.  FIG. 9I  is an oscillogram of a receiving signal BSr generated by a present receiver B 12  according to another embodiment. The receiving signals BSr, at the time points Bt 1 , Bt 2 , are two pulse signals BSp 1 , BSp 2 , respectively; the pulse signals BSp 1 , BSp 2  correspond to the position BA of the first straight ray pattern BL 1  and the position BB of the second straight ray pattern BL 2 , respectively. For the sake of simplicity and brevity, the two pulse signals respectively correspond to the position BC of the first straight ray pattern BL 1  and the position BD of second straight ray pattern BL 2  are omitted. According to one embodiment of the present invention, the receiver B 12  receives the wireless signal BSn from the transmitter B 11  at the reference time Bt 0 . Further, the receiving signal BSr generated by the receiver B 12  is received and stored by the controller B 13 . 
     Moreover, there is a time interval (or time difference) Bt between the first time Bt 1  and the second time Bt 2 , and the time difference is the time difference between the central time points of the pulse signal BSp 1 , BSp 2 ; that is, Bt=Bt 2 −Bt 1 . 
     It should be noted that, when implementing this embodiment, the microprocessor within the controller B 13  can record the time point of the rising or falling edge of two consecutive pulse signals BS 1 , BS 2 , so that it can further compute the central time points of the pulse signals BS 1 , BS 2 , thereby obtaining a more accurate time difference. 
     Moreover, a mean value of the first time Bt 1  and the second time Bt 2  can be calculated; the mean value is (Bt 1 +Bt 2 )/2. A time difference between the mean value and the reference time Bt 0  is (Bt 1 +Bt 2 )/2−Bt 0 ; this is the time required for the first straight ray pattern BL 1  or second straight ray pattern BL 2  to rotate from the reference angle to the receiver B 12  of the object BT. Furthermore, a rotation angle ψ can be calculated by multiplying the time difference between the mean value (i.e., (Bt 1 +Bt 2 )/2) and the reference time Bt 0  by the angular velocity co, see the following equation (2): 
       ψ=ω*(( Bt 1+ Bt 2)/2− Bt 0)  (2)
 
     According to one embodiment of the present invention, the controller B 13  uses the above-mentioned rotation angle ψ to compute the two-dimensional coordinate. 
       FIG. 9J  is a top view illustrating the use of the present coordinate sensing device B 1  to scan two objects BT 1 , BT 2  according to one embodiment. In the present embodiment, both the two objects BT 1 , BT 2  have a receiver B 12  disposed thereon. As illustrated in  FIG. 9J , when two objects BT 1 , BT 2  is spaced from the rotation center BO with different distances, each of the objects BT 1 , BT 2  forms a different scan angle Bθ 1 , Bθ 2  with the rotation center BO; that is, Bθ 1  is different from Bθ 2 . For example, the closer the distance between the object BT 1  and the rotation center BO, the greater the scan angle Bθ 1 , and therefore, the greater the time difference between the first time Bt 1  and the second time Bt 2 . This is because that when the distance between the object BT 1  and rotation center BO gets closer, the speed at which the first straight ray pattern BL 1  and the second straight ray pattern BL 2  scan becomes slower, thereby leading to a longer time difference and a greater scan angle Bθ 1 . On the contrary, when the distance between the object BT 2  and the rotation center BO gets farther, the scan angle Bθ 2  becomes smaller, and hence, the time difference between the first time Bt 1  and the second time Bt 2  shortens. This is because that when the distance between the object BT 2  and the rotation center BO gets farther, the speed at which the first straight ray pattern BL 1  and the second straight ray pattern BL 2  scan is faster, thereby leading to a shorter time difference and a smaller scan angle Bθ 2 . 
       FIG. 9K  is a top view illustrating the use of the present coordinate sensing device B 1  to scan an object BT according to one embodiment. As illustrated in  FIG. 9K , in the present embodiment, there is a distance BS between the rotation center BO and the object BT, when viewed from the top, and the position at which the first straight ray pattern BL 1  rotates and passes through the object BT is a first point position BP 1 . Meanwhile, for the second straight ray pattern BL 2 , there is a second point position BP 2  that is spaced from the rotation center BO by the same distance BS. In this case, the first point position BP 1  and the rotation center BO form a first straight line, the second point position BP 2  and the rotation center BO form a second straight line, and the first straight line and the second straight line have an included angle Bθ therebetween. Since the first straight ray pattern BL 1  and the second straight ray pattern BL 2  have the pre-determined angular velocity ω when they rotate about the rotation center BO, the above-mentioned included angle Bθ would equal to the product of the pre-determined angular velocity ω and the time difference Bt, see the following equation (3): 
         Bθ=ω*Bt   (3)
 
     Moreover, there is a pre-determined spacing BS between the first straight ray pattern BL 1  and the second straight ray pattern BL 2  (in this embodiment, the spacing BS has a fixed value), and as illustrated in  FIG. 9K , the relationship between the spacing BS and the distance Br satisfies the following equation (4): 
         Br=BS /(2*sin(ω* Bt/ 2))  (4)
 
     Using the above-mentioned equation (2) and equation (4), the controller B 13  may compute the angle ψ and the distance BS between the rotation center BO and the receiver B 12  (i.e., the object BT). Next, the controller B 13  may obtain the coordinate (x,y) representing the position of the object BT in the two-dimensional plane of the locale according to following equation (5): 
         x=Br *cos(ψ), y=Br *sin(ψ)  (5)
 
     where x is an x-coordinate distance of the object BT (or receiver B 12 ) in the horizontal plane BP, and y is a y-coordinate distance of the object BT in the horizontal plane BP. 
     In view of the foregoing, the microprocessor of the controller B 13  may compute two sets of coordinate position (x,y) of the object BT in the horizontal plane BP according to the angular velocity ω at which the first straight ray pattern BL 1  and the second straight ray pattern BL 2  rotate, the spacing BS between the first straight ray pattern BL 1  and the second straight ray pattern BL 2 , the time difference Bt between the first time Bt 1  and the second time Bt 2 , and the reference time Bt 0 . Therefore, the present invention embodiment may accurately determine the precise location of the object BT in a specific locale. 
     According to some embodiments, a monitoring apparatus includes: a first operational device arranged to perform a first predetermined function and accordingly transmit a first instruction signal; a second operational device arranged to receive a second instruction signal and accordingly perform a second predetermined function; a first monitoring device coupled to the first operational device for generating a first detecting event according to an operation of the first operational device; and a second monitoring device coupled to the second operational device for generating a second detecting event according to the operation of the second operational device. The first monitoring device is wirelessly coupled to the second monitoring device, and the first detecting event and the second detecting event are used to determine if the first operational device and the second operational device perform the first predetermined function and the second predetermined function respectively. 
     According to some embodiments, a monitoring method includes: arranging a first operational device to perform a first predetermined function and accordingly transmitting a first instruction signal; arranging a second operational device to receive a second instruction signal and accordingly performing a second predetermined function; generating a first detecting event according to an operation of the first operational device; generating a second detecting event according to the operation of the second operational device; and using the first detecting event and the second detecting event to determine if the first operational device and the second operational device perform the first predetermined function and the second predetermined function respectively. 
     The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure.