Patent Publication Number: US-2016226545-A1

Title: Communication device

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority of Taiwan Patent Application No. 104102968 filed on Jan. 29, 2015, the entirety of which is incorporated by reference herein. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The disclosure generally relates to a communication device, and more specifically, to a communication device with a radiation element configured as both an antenna and a sensing pad. 
     2. Description of the Related Art 
     With the progress of mobile communication technology, mobile devices, for example, portable computers, mobile phones, tablet computers, multimedia players, and other hybrid functional portable electronic devices, have become more common. To satisfy the needs of users, mobile devices can usually perform wireless communication functions. Some functions cover a large wireless communication area; for example, mobile phones using 2G, 3G, and LTE (Long Term Evolution) systems and using frequency bands of 700 MHz, 850 MHz, 900 MHz, 1800 MHz, 1900 MHz, 2100 MHz, 2300 MHz, and 2500 MHz. Some functions cover a small wireless communication area; for example, mobile phones using Wi-Fi and Bluetooth systems and using frequency bands of 2.4 GHz, 5.2 GHz, and 5.8 GHz. 
     A conventional mobile device usually includes an antenna and a sensing pad, which are separate from each other, so as to support wireless communication and adjustment of radiation power. However, since there is limited space in a mobile device, the aforementioned antenna and sensing pad may be very close to each other, and this can lead to interference and poor radiation efficiency of the antenna. Accordingly, there is a need to design a novel mobile communication device for solving the problem of the prior art. 
     BRIEF SUMMARY OF THE INVENTION 
     In a preferred embodiment, the invention provides a communication device including a radiation element, an RF (Radio Frequency) choke element, a DC (Direct Current) block element, an SAR (Specific Absorption Rate) sensor, a transceiver, and a platform. The radiation element has the functions of both an antenna and a sensing pad. The radiation element is configured to receive a low-frequency signal and an RF signal. The RF choke element is configured to remove the RF signal. The DC block element is configured to remove the low-frequency signal. The radiation element is coupled through the RF choke element to the SAR sensor. The radiation element is further coupled through the DC block element to the transceiver. The platform is coupled to the SAR sensor and the transceiver. 
     In some embodiments, the SAR sensor is configured to process the low-frequency signal and obtain SAR information thereof accordingly. 
     In some embodiments, when a human body is close to the radiation element, an effective capacitance is formed between the radiation element and the human body. The low-frequency signal includes information of the effective capacitance. 
     In some embodiments, the transceiver is configured to process the RF signal and obtain a communication content thereof accordingly. 
     In some embodiments, the RF choke element includes an inductor, and the inductor has a relatively large inductance. 
     In some embodiments, the DC block element includes a capacitor, and the capacitor has a relatively large capacitance. 
     In some embodiments, the radiation element is further coupled to a ground voltage. 
     In some embodiments, the radiation element and the DC block element are implemented with a first metal element and a second metal element. The first metal element is separate from the second metal element. 
     In some embodiments, the first metal element is close to the second metal element, and a coupling gap is formed between the first metal element and the second metal element. 
     In some embodiments, the second metal element is coupled to the RF choke element and a ground voltage. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein: 
         FIG. 1  is a diagram of a communication device according to an embodiment of the invention; 
         FIG. 2  is a diagram of measurement of an effective capacitance according to an embodiment of the invention; 
         FIG. 3  is a diagram of an RF (Radio Frequency) choke element according to an embodiment of the invention; 
         FIG. 4  is a diagram of an RF choke element according to an embodiment of the invention; 
         FIG. 5  is a diagram of a DC (Direct Current) block element according to an embodiment of the invention; 
         FIG. 6  is a diagram of a DC block element according to an embodiment of the invention; 
         FIG. 7  is a diagram of a communication device according to an embodiment of the invention; 
         FIG. 8  is a diagram of a communication device according to an embodiment of the invention; and 
         FIG. 9  is a diagram of a communication device according to an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In order to illustrate the purposes, features and advantages of the invention, the embodiments and figures of the invention are shown in detail as follows. 
       FIG. 1  is a diagram of a communication device  100  according to an embodiment of the invention. The communication device  100  may be a mobile device with a communication function, such as a smart phone, a tablet computer, or a notebook computer. As shown in  FIG. 1 , the communication device  100  includes a radiation element  110 , an RF (Radio Frequency) choke element  120 , a DC (Direct Current) block element  130 , an SAR (Specific Absorption Rate) sensor  140 , a transceiver  150 , and a platform  160 . It should be understood that the communication device  100  may further include other elements, such as a battery, a display device, a touch control module, a speaker, and/or a housing (not shown), although they are not displayed in  FIG. 1 . 
     The radiation element  110  may be made of a conductive material, such as copper, silver, aluminum, iron, or their alloy. The shape and size of the radiation element  110  are not limited in the invention. For example, the radiation element  110  may substantially have a straight-line shape, a loop shape, or an inverted F-shape. The radiation element  110  has the functions of both an antenna and a sensing pad. The radiation element  110  is configured to receive a low-frequency signal Si and an RF signal S 2 . In some embodiments, the low-frequency signal S 1  is a DC signal (i.e., its frequency is zero), and the RF signal S 2  has a frequency which is higher than 700 MHz. For example, the RF signal S 2  may be a mobile communication signal, such as an LTE (Long Term Evolution) signal, a 3G signal, or a GSM (Global System for Mobile Communication) signal. 
       FIG. 2  is a diagram of measurement of an effective capacitance CE according to an embodiment of the invention. As shown in  FIG. 2 , when a human body HB (or a conductor) is close to the radiation element  110 , an effective capacitance CE is formed between the radiation element  110  and the human body HB. The aforementioned low-frequency signal S 1  may include the information of the effective capacitance CE. By analyzing the information of the effective capacitance CE from the low-frequency signal S 1 , the spacing between the human body HB and the communication device  100  can be obtained, and therefore the corresponding SAR value can be calculated. 
     The RF choke element  120  is configured to remove the RF signal S 2 . The radiation element  110  is coupled through the RF choke element  120  to the SAR sensor  140 , such that the SAR sensor  140  can receive only the low-frequency signal S 1  from the radiation element  110 . The SAR sensor  140  is configured to process the low-frequency signal S 1  and obtain its SAR information accordingly. The DC block element  130  is configured to remove the low-frequency signal S 1 . The radiation element  110  is further coupled through the DC block element  130  to the transceiver  150 , such that the transceiver  150  can receive only the RF signal S 2  from the radiation element  110 . The transceiver  150  is configured to process the RF signal S 2  and obtain its communication content accordingly, such as voice information or digital data. The platform  160  may be a CPU (Central Processing Unit). The platform  160  is coupled to the SAR sensor  140  and the transceiver  150 , and is configured to analyze all information from the SAR sensor  140  and the transceiver  150 . 
     In the communication device  100  of the invention, the antenna is combined with the sensing pad, and they form a single radiation element  110 . In addition, the RF choke element  120  and the DC block element  130  are used to filter input signals, and therefore the low-frequency signal S 1  and the RF signal S 2 , received by the radiation element  110 , are transmitted to the SAR sensor  140  and the transceiver  150 , respectively. The above signals do not tend to interfere with each other. Since the antenna is integrated with the sensing pad, their total size can be further reduced. In comparison to the conventional design, the invention has at least the advantages of reducing the cost, minimizing the size, and enhancing the efficiency of using the elements. 
       FIG. 3  is a diagram of an RF choke element  320  according to an embodiment of the invention. The RF choke element  320  of  FIG. 3  may be applied to the communication device  100  of  FIG. 1 . The RF choke element  320  has a first terminal  321  coupled to the SAR sensor  140 , and a second terminal  322  coupled to the radiation element  110 . In the embodiment of  FIG. 3 , the RF choke element  320  includes an inductor L 1 . The inductor L 1  is coupled between the first terminal  321  and the second terminal  322  of the RF choke element  320 . The inductor L 1  has a relatively large inductance. For example, the aforementioned inductance may be greater than or equal to 10 nH. The RF choke element  320  is configured to remove the RF signal S 2  and retain the low-frequency signal S 1 . 
       FIG. 4  is a diagram of an RF choke element  420  according to an embodiment of the invention. The RF choke element  420  of  FIG. 4  may be applied to the communication device  100  of  FIG. 1 . The RF choke element  420  has a first terminal  421  coupled to the SAR sensor  140 , and a second terminal  422  coupled to the radiation element  110 . In the embodiment of  FIG. 4 , the RF choke element  420  includes an inductor L 1  and a capacitor C 1 . The inductor L 1  is coupled between the first terminal  421  and the second terminal  422  of the RF choke element  420 . The inductor L 1  has a relatively large inductance. For example, the aforementioned inductance may be greater than or equal to 10 nH. The capacitor C 1  is coupled between the second terminal  422  of the RF choke element  420  and a ground voltage VSS. In alternative embodiments, the capacitor C 1  is coupled between the first terminal  421  of the RF choke element  420  and the ground voltage VSS. The RF choke element  420  is configured to remove the RF signal S 2  and retain the low-frequency signal S 1 . 
       FIG. 5  is a diagram of a DC block element  530  according to an embodiment of the invention. The RF choke element  530  of  FIG. 5  may be applied to the communication device  100  of  FIG. 1 . The DC block element  530  has a first terminal  531  coupled to the transceiver  150 , and a second terminal  532  coupled to the radiation element  110 . In the embodiment of  FIG. 5 , the DC block element  530  includes a capacitor C 1 . The capacitor C 1  is coupled between the first terminal  531  and the second terminal  532  of the DC block element  530 . The capacitor C 1  has a relatively large capacitance. For example, the aforementioned capacitance may be greater than or equal to 10 pF. The DC block element  530  is configured to remove the low-frequency signal S 1  and retain the RF signal S 2 . 
       FIG. 6  is a diagram of a DC block element  630  according to an embodiment of the invention. The RF choke element  630  of  FIG. 6  may be applied to the communication device  100  of  FIG. 1 . The DC block element  630  has a first terminal  631  coupled to the transceiver  150 , and a second terminal  632  coupled to the radiation element  110 . In the embodiment of  FIG. 6 , the DC block element  630  includes a capacitor C 1  and an inductor L 1 . The capacitor C 1  is coupled between the first terminal  631  and the second terminal  632  of the DC block element  630 . The capacitor C 1  has a relatively large capacitance. For example, the aforementioned capacitance may be greater than or equal to 10 pF. The inductor L 1  is coupled between the first terminal  631  of the DC block element  630  and a ground voltage VSS. In alternative embodiments, the inductor L 1  is coupled between the second terminal  632  of the DC block element  630  and the ground voltage VSS. In other embodiments, the inductor L 1  may be replaced with another capacitor C 2  (not shown). The DC block element  630  is configured to remove the low-frequency signal S 1  and retain the RF signal S 2 . 
       FIG. 7  is a diagram of a communication device  700  according to an embodiment of the invention.  FIG. 7  is similar to  FIG. 1 . The difference between the two embodiments is that a radiation element  710  of the communication device  700  is a planar metal board, which is further coupled to a ground voltage VSS. A grounding point of the planar metal board may be positioned at a connection path between the radiation element  710  and the RF choke element  120 . Other features of the communication device  700  of  FIG. 7  are similar to those of the communication device  100  of  FIG. 1 . Accordingly, the two embodiments can achieve similar levels of performance. 
       FIG. 8  is a diagram of a communication device  800  according to an embodiment of the invention.  FIG. 8  is similar to  FIG. 1 . The difference between the two embodiments is that a radiation element  810  and a DC block element  830  of the communication device  800  are implemented with a first metal element  811  and a second metal element  812 . The first metal element  811  is separate from the second metal element  812 . The first metal element  811  may substantially have an L-shape. The second metal element  812  may substantially have another L-shape. The length of the second metal element  812  may be longer than that of the first metal element  811 . The first metal element  811  is close to the second metal element  812 , and a coupling gap GC 1  is formed between the first metal element  811  and the second metal element  812 . The width of the coupling gap GC 1  may be shorter than 2 mm. The first metal element  811  is coupled to the transceiver  150 . The second metal element  812  is coupled to the RF choke element  120  and a ground voltage VSS. Other features of the communication device  800  of  FIG. 8  are similar to those of the communication device  100  of  FIG. 1 . Accordingly, the two embodiments can achieve similar levels of performance. 
       FIG. 9  is a diagram of a communication device  900  according to an embodiment of the invention.  FIG. 9  is similar to  FIG. 1 . The difference between the two embodiments is that a radiation element  910  of the communication device  900  is a metal element having any shape. For example, the metal element may substantially have a triangular shape, a circular shape, an elliptical shape, a rectangular shape, or a trapezoidal shape. Other features of the communication device  900  of  FIG. 9  are similar to those of the communication device  100  of  FIG. 1 . Accordingly, the two embodiments can achieve similar levels of performance. 
     The invention proposes a novel communication device with a compound element including an antenna and a sensing pad. In addition, an RF choke element and a DC block element are used, and therefore the invention can not only avoid signal interference but also reduce design space. 
     Note that the above element sizes, element shapes, and frequency ranges are not limitations of the invention. An antenna engineer can adjust these settings or values according to different requirements. It should be understood that the communication device of the invention is not limited to the configurations of  FIGS. 1-9 . The invention may merely include any one or more features of any one or more embodiments of  FIGS. 1-9 . In other words, not all of the features shown in the figures should be implemented in the communication device of the invention. 
     Use of ordinal terms such as “first”, “second”, “third”, etc., in the claims to modify a claim element does not by itself connote any priority, precedence, or order of one claim element over another or the temporal order in which acts of a method are performed, but are used merely as labels to distinguish one claim element having a certain name from another element having the same name (but for use of the ordinal term) to distinguish the claim elements. 
     It will be apparent to those skilled in the art that various modifications and variations can be made in the invention. It is intended that the standard and examples be considered as exemplary only, with a true scope of the disclosed embodiments being indicated by the following claims and their equivalents.