Patent Publication Number: US-8979594-B2

Title: Electrical receptacle

Description:
FIELD OF THE INVENTION 
     The present invention relates to an electrical receptacle, and more particularly to an electrical receptacle with a signal interface, in which a portion of the signal interface structure segments (e.g. the fixture segments) the signal interface are previously installed on a rear cover. 
     BACKGROUND OF THE INVENTION 
     Nowadays, the functions of various electronic products become more powerful. Since handheld devices are increasingly popular, the demands on the data transmission between various electronic products or handheld devices are increased. 
     Generally, the electrical receptacle for the electronic product has a single signal interface such as a universal serial bus 2.0 (also referred as USB 2.0) signal interface, an external Serial ATA (also referred as eSATA) signal interface, a universal serial bus 3.0 (also referred as USB 3.0) signal interface. Moreover, the electrical receptacle may include an image transmission signal interface such as a display port signal interface or a high definition multimedia interface (HDMI) signal interface. Moreover, the electrical receptacle may include at least two of the above-mentioned signal interfaces. Recently, the manufacturers pay much attention to the integration of more terminals or conductive wires into the electrical receptacle. 
     Regardless of whether the electrical receptacle has a single signal interface, multiple signal interfaces, a display port signal interface and/or a HDMI signal interface, there is a need of providing an electrical receptacle with reduced assembling complexity and reduced fabricating cost in order to comply with various size specifications of the electronic products or the handheld devices. 
     Moreover, there is also a need of providing an electrical receptacle with reduced signal interference between adjacent high-speed signal interfaces. 
     SUMMARY OF THE INVENTION 
     The present invention provides an electrical receptacle for distributing some of the signal interface structure segments to the rear cover, so that the signal interface structures are not excessively centralized to the plastic main body. 
     The present invention also provides an electrical receptacle having a single type of signal interface or various types of signal interfaces and having a novel receptacle structure. 
     The present invention further provides an electrical receptacle with reduced signal interference between adjacent high-speed signal interfaces. 
     In accordance with an aspect of the present invention, there is provided an electrical receptacle. The electrical receptacle includes a first plastic main body, a tongue plate structure, plural signal interface structure segments, and a second plastic main body. At least two of the plural signal interface structure segments are located at a top side and a bottom side of the tongue plate structure, respectively. The second plastic main body has at least one structure segment fixing space. At least a first portion of the plural signal interface structure segments are previously accommodated and fixed within the at least one structure segment fixing space. After the second plastic main body with the first portion of the plural signal interface structure segments and the first plastic main body are combined together, the second plastic main body, the first plastic main body, the tongue plate structure and a second portion of the plural signal interface structure segments are assembled into the electrical receptacle. 
     In an embodiment, the tongue plate structure is combined with or integrally formed with the first plastic main body, and the tongue plate structure is a single tongue plate structure or a composite tongue plate structure including at least two plates. 
     In an embodiment, the composite tongue plate structure is at least composed of two plastic tongue plates. Alternatively, the composite tongue plate structure is at least composed of one plastic tongue plate and one circuit board. Alternatively, the composite tongue plate structure is at least composed of two plastic insert molding tongue plates with at least one signal interface structure segment each. Alternatively, the composite tongue plate structure is at least composed of one plastic tongue plate and one plastic insert molding tongue plate with at least one signal interface structure segment. 
     In an embodiment, the single tongue plate structure or the plastic tongue plate of the composite tongue plate structure is a fixed plastic tongue plate or a removable plastic tongue plate. In addition, the circuit board is a removable circuit board, and the plastic insert molding tongue plate is a fixed plastic insert molding tongue plate or a removable plastic insert molding tongue plate. 
     In an embodiment, the second portion of the plural signal interface structure segments are installed on the first plastic main body, or installed on the tongue plate structure, or installed in a first docking space beside a first surface of the tongue plate structure, or installed in a second docking space beside a second surface of the tongue plate structure, or installed on the second plastic main body, or installed in the at least one docking space including at least one of the first docking space and the second docking space. 
     In an embodiment, the at least two signal interface structure segments located at the top side and the bottom side of the tongue plate structure are respectively exposed to or arranged beside the first docking space and the second docking space. Moreover, the at least two signal interface structure segments are both metallic contact segments, or at least one of the at least two signal interface structure segments is a metallic contact segment, and the metallic contact segment belongs to the second portion of the plural signal interface structure segments. 
     In an embodiment, the plural signal interface structure segments includes at least one contact resilience arm segment, which is accommodated within at least one corresponding slot of the tongue plate structure, wherein a front end and a rear end of the contact resilience arm segment are respectively protruded from the first surface and the second surface of the tongue plate structure. 
     In an embodiment, an extension segment or an extension wire or a fixture segment of the plural signal interface structure segments electrically connected with the contact resilience arm segment belongs to the first portion of the plural signal interface structure segments and is previously accommodated and fixed within the at least one structure segment fixing space. 
     In an embodiment, an extension segment or a fixture segment belongs to the first portion of the plural signal interface structure segments. Moreover, a pin segment or a welding segment connected to a rear end of the extension segment or the fixture segment is not penetrated through or accommodated within any structural member or only penetrated through or accommodated within one of the first plastic main body and the second plastic main body. 
     In an embodiment, a first end of the pin segment or a first end of the welding segment is electrically connected with the extension segment or electrically connected with the fixture segment, and a second end of the pin segment or a second end of the welding segment is welded to a motherboard, so that none of the structural member is arranged between the first portion of the plural signal interface structure segments and the motherboard or the first portion of the plural signal interface structure segments are only installed on one of the first plastic main body and the second plastic main body. 
     In an embodiment, a contact pad or a contact resilience arm segment or a contact segment, or an extension wire or an extension segment, or a fixture segment, or a pin segment or a welding segment belongs to the second portion of the plural signal interface structure segments, wherein the second portion of the plural signal interface structure segments which are installed on the first plastic main body exclude the pin segment or the welding segment. 
     In an embodiment, the first portion of the plural signal interface structure segments and the second portion of the plural signal interface structure segments are collaboratively defined as plural signal interfaces. Each signal interface unit of the plural signal interfaces is composed of four structure segments: (1) a contact pad or a contact resilience arm segment or a contact segment, (2) an extension wire or an extension segment, (3) a fixture segment, and (4) a pin segment or a welding segment. Alternatively, each signal interface unit of the plural signal interfaces is composed of three structure segments: (1) a contact pad or a contact resilience arm segment or a contact segment, (2) an extension wire or an extension segment, and (3) a pin segment or a welding segment. Alternatively, each signal interface unit of the plural signal interfaces is composed of two structure segment: (1) a contact and extension segment or a contact and extension wire, and (2) a pin segment or a welding segment. Each of the signal interfaces includes plural conductive terminals, which are separated from each other and not electrically with each other. 
     In an embodiment, the second plastic main body is a rear cover, which is combined with the first plastic main body or the tongue plate structure or integrally formed with the tongue plate structure. The rear cover has at least one sidewall exposed to or arranged beside at least one docking space mating with an electrical plug. Alternatively, the rear cover has at least one position-limiting fixing recess for previously accommodating and fixing the first portion of the plural signal interface structure segments. Alternatively, the rear cover has at least one receiving hole for accommodating at least one pin segment of the first portion of the plural signal interface structure segments or the second portion of the plural signal interface structure segments. Alternatively, the rear cover has at least one fixing recess for previously accommodating and fixing the first portion of the plural signal interface structure segments and at least one receiving hole for accommodating at least one pin segment of the first portion of the plural signal interface structure segments or the second portion of the plural signal interface structure segments. 
     In an embodiment, the electrical receptacle further includes a metallic casing. The metallic casing is sheathed around the first plastic main body, or the metallic casing is sheathed around an outer periphery of a combination of the first plastic main body and the second plastic main body, wherein no signal interface structure segment is installed on the first plastic main body, or no any other protrusion plate parallel with and separated from the plastic tongue plate is arranged under the plastic tongue plate. Alternatively, the first plastic main body has two lateral walls extended toward a front side thereof, or the first plastic main body is not integrally formed with the tongue plate structure. Moreover, a shared profile mating with various signal interfaces of an electrical plug is defined by front peripheries of the two lateral walls. 
     In an embodiment, the plural signal interface structure segments are collaboratively defined as a signal interface complying with an USB 2.0 or USB 3.0 communication protocol and an eSATA communication protocol. Alternatively, the plural signal interface structure segments are collaboratively defined as a single-type USB signal interface complying with an USB 2.0 or USB 3.0 communication protocol. Alternatively, the plural signal interface structure segments are collaboratively defined as a signal interface complying with a high definition multimedia interface (HDMI) communication protocol. Alternatively, the plural signal interface structure segments are collaboratively defined as a signal interface complying with a display port communication protocol. 
     In accordance with another aspect of the present invention, there is provided an electrical receptacle having at least one docking space for accommodating an electrical plug. The electrical receptacle includes a plastic main body, a tongue plate structure, plural signal interface structure segments, and a rear cover. The tongue plate structure can be accommodated within a tongue plate receiving space of the electrical plug. The rear cover has at least one structure segment fixing space. At least a first portion of the plural signal interface structure segments are previously accommodated and fixed within the at least one structure segment fixing space. The tongue plate structure is combined with or integrally with the one of the plastic main body and the rear cover. The rear cover with the first portion of the plural signal interface structure segments, the plastic main body, the tongue plate structure and a second portion of the plural signal interface structure segments are assembled into the electrical receptacle. 
     In an embodiment, the tongue plate structure is combined with or integrally formed with the plastic main body, and the tongue plate structure is a single tongue plate structure or a composite tongue plate structure including at least two plates, wherein the single tongue plate structure or the composite tongue plate structure is an only tongue plate structure of the electrical receptacle. 
     In an embodiment, the composite tongue plate structure is at least composed of two plastic tongue plates. Alternatively, the composite tongue plate structure is at least composed of one plastic tongue plate and one circuit board. Alternatively, the composite tongue plate structure is at least composed of two plastic insert molding tongue plates with at least one signal interface structure segment each. Alternatively, the composite tongue plate structure is at least composed of one plastic tongue plate and one plastic insert molding tongue plate with at least one signal interface structure segment. 
     In an embodiment, the single tongue plate structure or the plastic tongue plate of the composite tongue plate structure is a fixed plastic tongue plate or a removable plastic tongue plate, and the circuit board is a removable circuit board, and the plastic insert molding tongue plate is a fixed plastic insert molding tongue plate or a removable plastic insert molding tongue plate. 
     In an embodiment, at least two of the plural signal interface structure segments are located at a top side and a bottom side of the tongue plate structure, respectively. 
     In an embodiment, the second portion of the plural signal interface structure segments are installed on the plastic main body, or installed on the tongue plate structure, or installed in a first docking space beside a first surface of the tongue plate structure, or installed in a second docking space beside a second surface of the tongue plate structure, or installed on the rear cover, or installed in the at least one docking space including at least one of the first docking space and the second docking space. 
     In an embodiment, the at least two signal interface structure segments located at the top side and the bottom side of the tongue plate structure are respectively exposed to or arranged beside the first docking space and the second docking space. Moreover, the at least two signal interface structure segments are both metallic contact segments, or at least one of the at least two signal interface structure segments is a metallic contact segment, and the metallic contact segment belongs to the second portion of the plural signal interface structure segments. 
     In an embodiment, the plural signal interface structure segments includes at least one contact resilience arm segment, which is accommodated within at least one corresponding slot of the tongue plate structure, wherein a front end and a rear end of the contact resilience arm segment are respectively protruded from the first surface and the second surface of the tongue plate structure. 
     In an embodiment, an extension segment or a fixture segment of the plural signal interface structure segments electrically connected with the contact resilience arm segment belongs to the first portion of the plural signal interface structure segments and is previously accommodated and fixed within the at least one structure segment fixing space. 
     In an embodiment, an extension segment or a fixture segment belongs to the first portion of the plural signal interface structure segments. Moreover, a pin segment or a welding segment connected to a rear end of the extension segment or the fixture segment is not penetrated through or accommodated within any structural member or only penetrated through or accommodated within one of the plastic main body and the rear cover. 
     In an embodiment, a first end of the pin segment or a first end of the welding segment is electrically connected with the extension segment or electrically connected with the fixture segment, and a second end of the pin segment or a second end of the welding segment is welded to a motherboard, so that none of the structural member is arranged between the first portion of the plural signal interface structure segments and the motherboard or the first portion of the plural signal interface structure segments are only installed on one of the plastic main body and the rear cover. 
     In an embodiment, a contact pad or a contact resilience arm segment or a contact segment, or an extension wire or an extension segment, or a fixture segment, or a pin segment or a welding segment belongs to the second portion of the plural signal interface structure segments, wherein the second portion of the plural signal interface structure segments which are installed on the first plastic main body exclude the pin segment or the welding segment. 
     In an embodiment, the first portion of the plural signal interface structure segments and the second portion of the plural signal interface structure segments are collaboratively defined as plural signal interfaces. Each signal interface unit of the plural signal interfaces is composed of four structure segments: (1) a contact pad or a contact resilience arm segment or a contact segment, (2) an extension wire or an extension segment, (3) a fixture segment, and (4) a pin segment or a welding segment. Alternatively, each signal interface unit of the plural signal interfaces is composed of three structure segments: (1) a contact pad or a contact resilience arm segment or a contact segment, (2) an extension wire or an extension segment, and (3) a pin segment or a welding segment. Alternatively, each signal interface unit of the plural signal interfaces is composed of two structure segment: (1) a contact and extension segment or a contact and extension wire, and (2) a pin segment or a welding segment. Each of the signal interfaces includes plural conductive terminals, which are separated from each other and not electrically with each other. 
     In an embodiment, the rear cover is combined with the plastic main body or the tongue plate structure or integrally formed with the tongue plate structure. The rear cover has at least one sidewall exposed to or arranged beside the at least one docking space, or the rear cover has at least one position-limiting fixing recess for previously accommodating and fixing the first portion of the plural signal interface structure segments, or the rear cover has at least one receiving hole for accommodating at least one pin segment of the first portion of the plural signal interface structure segments or the second portion of the plural signal interface structure segments, or the rear cover has at least one fixing recess for previously accommodating and fixing the first portion of the plural signal interface structure segments and at least one receiving hole for accommodating at least one pin segment of the first portion of the plural signal interface structure segments or the second portion of the plural signal interface structure segments. 
     In an embodiment, the plural signal interface structure segments are collaboratively defined as a first signal interface complying with an eSATA communication protocol, and collaboratively defined as a second signal interface having plural contact resilience arm segments and complying with a USB 2.0 communication protocol. Alternatively, the plural signal interface structure segments are collaboratively defined as the second signal interface and a third signal interface so as to comply with a USB 3.0 communication protocol. 
     In an embodiment, the electrical receptacle further includes a metallic casing. The metallic casing is sheathed around the plastic main body, or the metallic casing is sheathed around an outer periphery of a combination of the plastic main body and the rear cover, wherein no signal interface structure segment is installed on the plastic main body, or no any other protrusion plate parallel with and separated from the plastic tongue plate is arranged under the plastic tongue plate. Alternatively, the plastic main body has two lateral walls extended toward a front side thereof, or the plastic main body is not integrally formed with the tongue plate structure. Moreover, a shared profile mating with various signal interfaces of the electrical plug is defined by front peripheries of the two lateral walls. 
     The above objects and advantages of the present invention will become more readily apparent to those ordinarily skilled in the art after reviewing the following detailed description and accompanying drawings, in which: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic assembled view illustrating an electrical receptacle according to a first embodiment of the present invention; 
         FIG. 2  is a schematic exploded view illustrating the electrical receptacle of the first embodiment; 
         FIG. 3  is a schematic perspective view illustrating the combination of the USB 2.0 signal interface and the second plastic main body of the electrical receptacle of the first embodiment; 
         FIG. 4  is a schematic exploded view illustrating the electrical receptacle of the first embodiment and taken along another viewpoint; 
         FIG. 5  is a schematic perspective view illustrating the combination of the USB 2.0 signal interface and the second plastic main body of the electrical receptacle of the first embodiment and taken along another viewpoint; 
         FIG. 6  is a schematic side view illustrating the electrical receptacle of the first embodiment; 
         FIG. 7  is a schematic side view illustrating an electrical receptacle to be mounted on a motherboard according to a second embodiment of the present invention; 
         FIG. 8  is a schematic assembled view illustrating an electrical receptacle according to a third embodiment of the present invention; 
         FIG. 9  is a schematic exploded view illustrating the electrical receptacle of the third embodiment; 
         FIG. 10  is a schematic exploded view illustrating the electrical receptacle of the third embodiment and taken along another viewpoint; 
         FIG. 11  is a schematic side view illustrating the electrical receptacle to be mounted on a motherboard according to the third embodiment of the present invention; 
         FIG. 12  is a schematic side view illustrating the electrical receptacle to be mounted on a motherboard according to a fourth embodiment of the present invention; 
         FIG. 13  is a schematic side view illustrating the electrical receptacle according to a fifth embodiment of the present invention; 
         FIG. 14  is a schematic side view illustrating the electrical receptacle according to a sixth embodiment of the present invention; 
         FIG. 15  is a schematic side view illustrating the electrical receptacle to be mounted on a motherboard according to a seventh embodiment of the present invention; 
         FIG. 16  is a schematic side view illustrating the electrical receptacle according to an eighth embodiment of the present invention; 
         FIG. 17  is a schematic side view illustrating the electrical receptacle according to a ninth embodiment of the present invention; 
         FIG. 18  is a schematic side view illustrating the electrical receptacle according to a tenth embodiment of the present invention; 
         FIG. 19  is a schematic side view illustrating the electrical receptacle to be mounted on a motherboard according to an eleventh embodiment of the present invention; 
         FIG. 20  is a schematic exploded view illustrating an electrical receptacle according to a twelfth embodiment of the present invention; 
         FIG. 21  is a schematic exploded view illustrating the electrical receptacle of the twelfth and taken along another viewpoint; 
         FIG. 22  is a schematic exploded view illustrating an electrical receptacle according to a thirteenth embodiment of the present invention; 
         FIG. 23  is a schematic exploded view illustrating the electrical receptacle of the thirteenth and taken along another viewpoint; 
         FIG. 24  is a schematic exploded view illustrating an electrical receptacle according to a fourteenth embodiment of the present invention; 
         FIG. 25  is a schematic exploded view illustrating the electrical receptacle of the fourteenth and taken along another viewpoint; 
         FIG. 26  is a schematic side view illustrating the electrical receptacle to be mounted on a motherboard according to a fifteenth embodiment of the present invention; 
         FIG. 27  is a schematic exploded view illustrating an electrical receptacle according to a sixteenth embodiment of the present invention; 
         FIG. 28  is a schematic exploded view illustrating an electrical receptacle according to a seventeenth embodiment of the present invention; 
         FIG. 29  is a schematic exploded view illustrating the electrical receptacle of the seventeenth and taken along another viewpoint; 
         FIG. 30  is a schematic exploded view illustrating an electrical receptacle according to an eighteenth embodiment of the present invention; 
         FIG. 31  is a schematic exploded view illustrating the electrical receptacle of the eighteenth and taken along another viewpoint; 
         FIG. 32  is a schematic exploded view illustrating an electrical receptacle according to a nineteenth embodiment of the present invention; 
         FIG. 33  is a schematic exploded view illustrating the electrical receptacle of the nineteenth and taken along another viewpoint; 
         FIG. 34  is a schematic side view illustrating an electrical receptacle to be mounted on a motherboard according to a twentieth embodiment of the present invention; 
         FIG. 35  is a schematic side view illustrating an electrical receptacle to be mounted on a motherboard according to a twenty-first embodiment of the present invention; 
         FIG. 36  is a schematic side view illustrating an electrical receptacle according to a twenty-second embodiment of the present invention; 
         FIG. 37  is a schematic side view illustrating an electrical receptacle to be mounted on a motherboard according to a twenty-third embodiment of the present invention; 
         FIG. 38  is a schematic exploded view illustrating an electrical receptacle according to a twenty-fourth embodiment of the present invention; 
         FIG. 39  is a schematic exploded view illustrating the electrical receptacle of the twenty-fourth and taken along another viewpoint; 
         FIG. 40  is a schematic side view illustrating an electrical receptacle according to a twenty-fifth embodiment of the present invention; 
         FIG. 41  is a schematic side view illustrating an electrical receptacle according to a twenty-sixth embodiment of the present invention; 
         FIG. 42  is a schematic side view illustrating an electrical receptacle according to a twenty-seventh embodiment of the present invention; 
         FIG. 43  is a schematic side view illustrating an electrical receptacle according to a twenty-eighth embodiment of the present invention; 
         FIG. 44  is a schematic side view illustrating an electrical receptacle according to a twenty-ninth embodiment of the present invention; 
         FIG. 45  is a schematic side view illustrating an electrical receptacle according to a thirtieth embodiment of the present invention; 
         FIG. 46  is a schematic side view illustrating the electrical receptacle to be mounted on a motherboard according to a thirty-first embodiment of the present invention; 
         FIG. 47  is a schematic side view illustrating the electrical receptacle according to a thirty-second embodiment of the present invention; 
         FIG. 48  is a schematic exploded view illustrating an electrical receptacle according to a thirty-third embodiment of the present invention; 
         FIG. 49  is a schematic exploded view illustrating the electrical receptacle of the thirty-third and taken along another viewpoint 
         FIG. 50  is a schematic side view illustrating the electrical receptacle to be mounted on a motherboard according to a thirty-fourth embodiment of the present invention; 
         FIG. 51  is a schematic exploded view illustrating an electrical receptacle according to a thirty-fifth embodiment of the present invention; 
         FIG. 52  is a schematic assembled view illustrating an electrical receptacle according to a thirty-sixth embodiment of the present invention; 
         FIG. 53  is a schematic front view illustrating the electrical receptacle of the thirty-sixth embodiment; 
         FIG. 54  is a schematic exploded view illustrating the electrical receptacle of the thirty-sixth embodiment; 
         FIG. 55  is a schematic exploded view illustrating the electrical receptacle of the thirty-sixth embodiment and taken along another viewpoint; 
         FIG. 56  is a schematic front view illustrating the electrical receptacle according to a thirty-seventh embodiment of the present invention; 
         FIG. 57  is a schematic exploded view illustrating the electrical receptacle of the thirty-seventh embodiment; 
         FIG. 58  is a schematic exploded view illustrating the electrical receptacle of the thirty-seventh embodiment and taken along another viewpoint; 
         FIG. 59  is a schematic cross-sectional view illustrating the electrical receptacle according to a thirty-eighth embodiment of the present invention; 
         FIG. 60  is a schematic cross-sectional view illustrating the electrical receptacle according to a thirty-ninth embodiment of the present invention; and 
         FIG. 61  is a schematic side view illustrating an electrical plug applied to the electrical receptacle of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The present invention provides an electrical receptacle. The concepts of the present invention may be applied to an electrical receptacle with a single kind of signal interface or an all-in-one signal interface. In addition, the concepts of the present invention may be applied to an electrical receptacle with a unidirectional or bidirectional conducting means. For example, the concepts of the present invention are at least applied to the electrical receptacle having a USB 2.0 or USB 3.0 signal interface and an eSATA signal interface to comply with an all-in-one signal interface protocol. Alternatively, the concepts of the present invention are at least applied to the electrical receptacle comprising a USB 2.0 or USB 3.0 signal interface with a unidirectional or bidirectional conducting means but without a foolproof profile. Alternatively, the concepts of the present invention may be applied to the electrical receptacle with a single type signal interface, for example the signal interface complying with a high definition multimedia interface (HDMI) protocol or the signal interface complying with a display port protocol. 
     Moreover, numerous modifications and alterations of the electrical receptacle may be made while retaining the teachings of the invention. For example, the structure of the electrical receptacle may comprise four individual components: (1) a plastic main body (or a hollow plastic main body) with an integral tongue plate or a plastic tongue plate of the composite tongue plate structure, (2) a circuit board of the composite tongue plate structure, (3) a rear cover (also referred as a covering member), and (4) a metallic casing. Alternatively, the structure of the electrical receptacle may comprise four individual components: (1) a plastic main body (or a hollow plastic main body), (2) a circuit board of the composite tongue plate structure, (3) a rear cover (also referred as a covering member) with an integral tongue plate of the composite tongue plate structure, and (4) a metallic casing. Alternatively, the structure of the electrical receptacle may comprise four individual components: (1) a plastic main body (or a hollow plastic main body), (2) a single tongue plate or a composite tongue plate structure, (3) a rear cover (also referred as a covering member), and (4) a metallic casing. It is to be noted that the following descriptions of preferred embodiments of this invention are presented herein for purpose of illustration and description only. 
     The plastic main body may be considered as a first plastic main body. The rear cover (also referred as a covering member), or an individual pressing plate (or pressing structure), or an integral combination of the rear cover (also referred as a covering member) and a pressing plate (or pressing structure) may be considered as a second plastic main body. 
     Moreover, according to the practical requirements, the manufacturer may determine whether a signal interface is installed on the plastic main body or not, whether two lateral walls are respectively extended from left/right sides of the plastic main body or not, whether there is any other protrusion plate parallel with and separated from the single tongue plate or the composite tongue plate structure to support the plastic main body, whether the plastic main body has a bottom part (base part) or not, or whether the plastic main body has a foolproof profile mating with different signal interfaces. Consequently, numerous modifications and alterations may be made while retaining the teachings of the invention. 
     Moreover, the plastic main body of the electrical receptacle of the present invention has two lateral walls, which are extended toward the front side. The two lateral walls and at least one of a bottom part of the plastic main body and the rear cover collectively define a docking recess. The electrical receptacle has at least one docking space including a first receptacle or a second docking space. The docking space is at least defined by the plastic tongue plate (or the composite tongue plate structure) within the docking recess and the plastic main body (or the rear cover). Alternatively, the docking space is further defined by a metallic casing. It is to be noted that the following descriptions of preferred embodiments of this invention are presented herein for purpose of illustration and description only. 
     The entrance of the docking recess at least comprises a shared profile mating with various signal interfaces of a corresponding electrical plug. It is preferred that the shared profile is located at the front peripheries of the two lateral walls. 
     Moreover, the tongue plate used in the electrical receptacle may be a plastic tongue plate. In views of the relationship between the tongue plate and the main body, the plastic tongue plate may be integrally formed with the plastic main body to be served as an extension structure (i.e. a fixed plate) of the plastic main body. Alternatively, the tongue plate is an individual component (e.g. a removable plastic tongue plate). Alternatively, the tongue plate and some other components may be combined as an individual component. It is to be noted that the following descriptions of preferred embodiments of this invention are presented herein for purpose of illustration and description only. 
     Moreover, the circuit board used in the electrical receptacle of the present invention is a removable circuit board. Of course, the circuit board may be accommodated within a receiving space of the plastic tongue plate or the removable plastic tongue plate. Alternatively, according to the practical requirements, the circuit board is not accommodated within the receiving space. 
     Moreover, a composite tongue plate structure used in the electrical receptacle of the present invention is at least composed of two plastic tongue plates. Alternatively, the composite tongue plate structure is at least composed of a plastic tongue plate and a circuit board. Alternatively, the composite tongue plate structure is at least composed of two plastic insert molding tongue plates, wherein each of the plastic insert molding tongue plate has at least one signal interface structure segment. Alternatively, the composite tongue plate structure is at least composed of a plastic tongue plate and a plastic insert molding tongue plate with at least one signal interface structure segment. 
     Moreover, the signal interface unit of any signal interface used in the electrical receptacle of the present invention may comprise a single conductive terminal or further comprise a contact pad and an extension wire. According to the specifications of the general electric connector, the signal interface unit is composed of four structure segments: (1) a metallic contact part such as a (metallic) contact resilience arm segment or a (metallic) contact pad or a (metallic) contact segment, (2) a (metallic) extension segment (or an extension wire), (3) a (metallic) fixture segment, and (4) a (metallic) pin segment (a welding segment). Due to these four structure segments, the signal interface unit is effective to completely transmit an interface signal. Of course, these structure segments may have different definitions, explanations or classifications. For example, by changing the definition and classification, the signal interface unit may be composed of two structure segments: (1) a (metallic) contact and extension segment (contact and extension wire), and (2) a (metallic) pin segment (a welding segment). Alternatively, the signal interface unit may be composed of three structure segments: (1) a (metallic) contact resilience arm part (a contact pad or a contact segment), (2) a (metallic) extension segment (or an extension wire), and (3) a (metallic) pin segment (a welding segment). Of course, the structure segments may have different explanations or classifications, which are well known to those skilled in the art. 
     Hereinafter, any signal interface used in the electrical receptacle of the embodiments as shown in  FIGS. 1˜14  will be illustrated by referring to the signal interface composed of four structure segments: (1) a metallic contact part such as a (metallic) contact resilience arm segment or a contact pad or a contact segment, (2) an extension segment (or an extension wire), (3) a fixture segment, and (4) a pin segment. Moreover, any signal interface used in the electrical receptacle of the embodiments as shown in other drawings will be illustrated by referring to a signal interface having an signal interface structure composed of three structure segments: (1) a metallic contact part such as a (metallic) contact resilience arm segment or a contact pad or a contact segment, (2) an extension segment (or an extension wire), and (3) a pin segment. That is, the features of the present invention are not restricted by the definition or classification of any signal interface. 
     Moreover, the structural relationship or spatial arrangement between the signal interfaces or the structure segments of various signal interfaces and other components or structures (e.g. the plastic main body, the single tongue plate, the composite tongue plate structure, or the rear cover) and the structural relationship or spatial arrangement between the single tongue plate, the composite tongue plate structure and above components or structures (e.g. the plastic main body or the rear cover) may be varied according to the practical requirements or according to the plastic insert molding process or the circuit board forming process. It is to be noted that the following descriptions of preferred embodiments of this invention are presented herein for purpose of illustration and description only. 
     Moreover, a metallic contact part of at least one signal interface is located at each of the top side and the bottom side of the single plastic tongue plate or the composite tongue plate structure of the electrical receptacle. Moreover, the two metallic contact parts on different positions of the top side and the bottom side of the plastic tongue plate are respectively exposed to or arranged beside different docking space. Alternatively, a metallic contact part of at least one signal interface is located at only the top side or the bottom side of the single plastic tongue plate or the composite tongue plate structure. 
     In a case that a metallic contact part of at least one signal interface is located at only the top side or the bottom side of the single plastic tongue plate or the composite tongue plate structure, the composite tongue plate structure of the present invention is not defined by a plastic tongue plate integrally formed with the plastic main body and another plastic tongue plate integrally formed with the rear cover. 
     In the following descriptions of preferred embodiments and clams of this invention, the concepts or mechanisms of arranging the components or structures may be implements by various specified embodiments. The specified embodiment includes but is not limited to the combination assembly (or detachable combination assembly), the integrally-formed assembly or the secondary processing assembly (including fastening or welding means). 
     The present invention will now be described more specifically with reference to the following embodiments. It is to be noted that the following descriptions of preferred embodiments of this invention are presented herein for purpose of illustration and description only. It is not intended to be exhaustive or to be limited to the precise form disclosed. 
     Hereinafter, a composite tongue plate structure including a fixed plastic tongue plate or a removable plastic tongue plate and a circuit board will be illustrated in more detail with reference to  FIGS. 1˜6 .  FIG. 1  is a schematic assembled view illustrating an electrical receptacle according to a first embodiment of the present invention.  FIG. 2  is a schematic exploded view illustrating the electrical receptacle of the first embodiment.  FIG. 3  is a schematic perspective view illustrating the combination of the USB 2.0 signal interface and the second plastic main body of the electrical receptacle of the first embodiment.  FIG. 4  is a schematic exploded view illustrating the electrical receptacle of the first embodiment and taken along another viewpoint.  FIG. 5  is a schematic perspective view illustrating the combination of the USB 2.0 signal interface and the second plastic main body of the electrical receptacle of the first embodiment and taken along another viewpoint.  FIG. 6  is a schematic side view illustrating the electrical receptacle of the first embodiment. 
     In this embodiment, the present invention will be illustrated by referring to an electrical receptacle including an eSATA signal interface and a USB 2.0 signal interface. As shown in  FIGS. 1˜6 , the electrical receptacle  10  comprises a first plastic main body  11 , a plastic tongue plate  111 , a circuit board  12 , and a second plastic main body  13 . The first plastic main body  11  has a first docking space  171  and a second docking space  172 . The plastic tongue plate  111  is fixed on a sidewall of a bottom part  114  of the first plastic main body  11  and extended toward the front side. 
     In this embodiment, the plastic tongue plate  111  is suspended toward the front side. Moreover, no any other protrusion plate parallel with and separated from the plastic tongue plate  111  is arranged under the plastic tongue plate  111  to support the first plastic main body  11 . That is, two lateral walls  113  are disposed on the bottom part  114  of the first plastic main body  11  and extended toward the front side. Moreover, a shared profile  1131  mating with different signal interfaces of an electrical plug (see  FIG. 61 ) is located at the front peripheries of the two lateral walls  113 . Consequently, the two lateral walls  113  can support the first plastic main body  11  and provide the shared profile  1131  to achieve the all-in-one electrical receptacle. 
     In this embodiment, the circuit board  12  is accommodated within a receiving space  1111 , which is located under the tongue plate  111  (see  FIG. 4 ). Moreover, the circuit board  12  and the tongue plate  111  may be in close contact with each other. Alternatively, the circuit board  12  is separated from the tongue plate  111  by a spacing interval, so that another signal interface can be interposed between the circuit board  12  and the tongue plate  111  and will be illustrated later. 
     In the embodiment, the first plastic main body  11  is a hollow plastic main body  11  (also referred as a plastic main body), and the plastic tongue plate  111  is arranged between the first docking space  171  and the second docking space  172  of the plastic main body  11 . In the embodiment, the first docking space  171  and the second docking space  172  are defined by the plastic tongue plate  111 , the circuit board  12  and the first plastic main body  11 . 
     Moreover, in this embodiment, the plastic tongue plate  111  and the circuit board  12  are both installed on the first plastic main body  11 . Alternatively, in the following embodiments, either the plastic tongue plate or the circuit board is installed on the first plastic main body  11 . 
     In the embodiment, any signal interface used in the electrical receptacle includes but is not limited to a first signal interface (e.g. an eSATA signal interface), or a second signal interface (e.g. a USB 2.0 signal interface), or a third signal interface (e.g. USB 3.0 signal interface). 
     The signal interface structure segment used in the electrical receptacle of the present invention is a part of the signal interface structure segments of any signal interface, for example a contact pad or a metallic contact resilience arm, an extension wire or an extension segment, a fixture segment, or a pin segment. According to the specifications of the general electric connector, any signal interface is composed of four kinds of the above-mentioned structure segments. Due to these four structure segments, the signal interface is effective to completely transmit interface signals. Of course, the signal interface structure may have different explanations or classifications, which are well known to those skilled in the art. 
     Please refer to  FIGS. 1˜6  again. From front to back, the signal interface structure segments of the eSATA signal interface  14  successively comprise a plurality of contact pads  141 , a plurality of extension wires  142 , a plurality of fixture segments  143 , and a plurality of pin segments (or welding segments)  144 . From front to back, the signal interface structure segments of the USB 2.0 signal interface  15  successively comprise a plurality of contact resilience arm segments  151 , a plurality of extension segments  152 , a plurality of fixture segments  153 , and a plurality of pin segments (or welding segments)  154 . That is, the USB 2.0 signal interface  15  comprises a plurality of USB 2.0 metallic terminals. 
     In this embodiment, the eSATA signal interface  14  is installed on the bottom surface of the circuit board  12 . The extension segments  152 , the fixture segments  153  and the pin segments  154  of the USB 2.0 signal interface  15  are arranged beside the eSATA signal interface  14 . The contact resilience arm segments  151  are penetrated upwardly from the bottom surface of the circuit board  12  and through four grooves  121  of the circuit board  12  and four slots  1112  of the plastic tongue plate  111 , and exposed to the first docking space  171  beside the plastic tongue plate  111 . 
     The plastic tongue plate  111  and the circuit board  12  may be collaboratively defined as a composite tongue plate structure. In this embodiment, the contact resilience arm segments  151  of the USB 2.0 signal interface  15  are located at the top side of the composite tongue plate structure and exposed to the first docking space  171 . The contact pads  141  of the eSATA signal interface  14  are located at the bottom side of the composite tongue plate structure and exposed to the second docking space  172 . 
     In this embodiment, the electrical receptacle  10  further comprises a metallic casing  16 , which is sheathed around the outer periphery of the combination of the first plastic main body  11  and the second plastic main body  13 . 
     In accordance with a key feature, the second plastic main body  13  is a rear cover with a plurality of structure segment fixing spaces. For example, the structure segment fixing spaces are fixing recesses  1311 ,  1312  with position-limiting structures (see  FIG. 4 ). The structure segment fixing spaces are used for accommodating and fixing the fixture segments  153  of the USB 2.0 signal interface  15  that are installed on the second plastic main body  13 . The fixture segments  143  of the eSATA signal interface  14  are accommodated within and installed on the region between the first plastic main body  11  and the second plastic main body  13 . 
     For assembling the electrical receptacle  10 , the above components may be moved in the assembling directions S 11 ˜S 14  as shown in  FIG. 2  and  FIG. 4 . Firstly, the fixture segments  153  of the USB 2.0 signal interface  15  are previously installed on the second plastic main body  13  along the assembling direction S 11 . Then, the circuit board  12  is installed on the first plastic main body  11  along the assembling direction S 12 . Then, the combination of the second plastic main body  13  and the USB 2.0 signal interface  15  is moved upwardly to be installed on the first plastic main body  11  along the assembling direction S 13 . After the metallic casing  16  is sheathed around the outer periphery of the combination of the first plastic main body  11  and the second plastic main body  13  along the assembling direction S 14 , the electrical receptacle  10  is assembled. 
     Moreover, after the first plastic main body  11  and the second plastic main body  13  are combined together, the pin segments  144  of the first signal interface  14  (i.e. the eSATA signal interface) are respectively accommodated within the seven receiving holes  133  (see  FIG. 2  and  FIG. 3 ) of the second plastic main body  13 . Whereas, the pin segments  154  of the second signal interface  15  (i.e. the USB 2.0 signal interface) are not accommodated within the second plastic main body  13 . 
     In this embodiment, the second plastic main body  13  (i.e. the rear cover) comprises a plurality of fixing recesses  1311 ,  1312  and a plurality of receiving holes  133 . Moreover, a sidewall  130  of the second plastic main body  13  (i.e. the rear cover) is exposed to or arranged beside the second docking space  172 . 
     Moreover, a motherboard  100  is shown in  FIG. 6  but not shown in  FIGS. 1˜5 . The motherboard  100  has a plurality of insertion holes  1001  and  1002 . The pin segments  144  of the first signal interface  14  (i.e. the eSATA signal interface) and the pin segments  154  of the second signal interface  15  (i.e. the USB 2.0 signal interface) are inserted into the insertion holes  1001  and  1002 , respectively. After the pin segments  144  and  154  are welded to the insertion holes  1001  and  1002 , the electrical receptacle  10  is welded on the motherboard  100 . 
     Moreover, after the second signal interface  15  is fixed on the second plastic main body  13  (i.e. the rear cover), no additional structural member is arranged between the pin segments  154  of the second signal interface  15  and the motherboard  100 . In other words, a first end  1541  of the pin segment  154  is connected to the fixture segment  153 , and a second end  1542  of the pin segment  154  is inserted into the motherboard  100 . Moreover, after the first signal interface  14  is installed on the first plastic main body  11 , the pin segments  144  are penetrated through the receiving holes  133  of the second plastic main body  13  (i.e. the rear cover) and then inserted into the motherboard  100 . 
     From the above discussions, some of the signal interface structure segments are previously distributed to the second plastic main body  13 . Since the signal interface structure segments are not excessively centralized to the first plastic main body  11 , the layout space is no longer crowded. Moreover, since the portions of the signal interface structure segments are previously installed on the second plastic main body  13 , the speed and convenience of assembling the other mechanisms will be enhanced. In such way, the electrical receptacle can be quickly assembled. 
       FIG. 7  is a schematic side view illustrating an electrical receptacle to be mounted on a motherboard according to a second embodiment of the present invention. As shown in  FIG. 7 , the electrical receptacle  20  comprises a first plastic main body  21 , a plastic tongue plate  211 , a circuit board  22 , and a second plastic main body  23 . The first plastic main body  21  has a first docking space  271  and a second docking space  272 . The plastic tongue plate  211  is fixed on a sidewall of a bottom part  214  of the first plastic main body  21  and extended toward the front side. Moreover, the circuit board  22  is disposed over the plastic tongue plate  211 . 
     From front to back, the signal interface structure segments first signal interface  24  (e.g. an eSATA signal interface) successively comprise a plurality of contact pads  241 , a plurality of extension wires, a plurality of fixture segments  243 , and a plurality of pin segments  244 . From front to back, the signal interface structure segments of the second signal interface  25  (e.g. a USB 2.0 signal interface) successively comprise a plurality of contact resilience arm segments  251 , a plurality of extension segments  252 , a plurality of fixture segments  253 , and a plurality of pin segments  254 . That is, the USB 2.0 signal interface  25  also comprises a plurality of USB 2.0 metallic terminals. 
     In this embodiment, the eSATA signal interface  24  is located at the top side of the circuit board  22 . The extension segments  252 , the fixture segments  253  and the pin segments  254  of the USB 2.0 signal interface  25  are arranged beside the eSATA signal interface  24 . The contact resilience arm segments  251  are penetrated downwardly from the top surface of the circuit board  22  and through four grooves  221  of the circuit board  22  and four slots  2112  of the plastic tongue plate  211 , and exposed to the first docking space  271  beside the plastic tongue plate  211   
     In this embodiment, the circuit board  22  and the plastic tongue plate  211  may be collaboratively defined as a composite tongue plate structure. The contact pads  241  of the eSATA signal interface  24  are located at the top side of the composite tongue plate structure and exposed to the second docking space  272 . Moreover, the contact resilience arm segments  251  of the USB 2.0 signal interface  25  are located at the bottom side of the composite tongue plate structure and exposed to the first docking space  271 . 
     Moreover, in this embodiment, a sidewall  230  of the second plastic main body  23  (i.e. the rear cover) is exposed to or arranged beside the second docking space  272 . 
     In this embodiment, the electrical receptacle  20  further comprises a metallic casing  26 , which is sheathed around the outer periphery of the combination of the first plastic main body  21  and the second plastic main body  23 . 
     In accordance with a key feature of the present invention, the second plastic main body  23  is a rear cover with a plurality of structure segment fixing spaces. For example, the structure segment fixing spaces are fixing recesses with position-limiting structures for accommodating and fixing the fixture segments  353  of the USB 2.0 signal interface  35  that are installed on the second plastic main body  23 . 
     Moreover, a motherboard  200  is shown in  FIG. 7 . The motherboard  200  has a plurality of insertion holes  2001  and  2002 . The pin segments  244  of the first signal interface  24  (i.e. the eSATA signal interface) and the pin segments  254  of the second signal interface  25  (i.e. the USB 2.0 signal interface) are inserted into the insertion holes  2001  and  2002 , respectively. After the pin segments  244  and  254  are welded to the insertion holes  2001  and  2002 , the electrical receptacle  20  is welded on the motherboard  200 . Moreover, after the second signal interface  25  is fixed on the second plastic main body  23  (i.e. the rear cover), no additional structural member is arranged between the pin segments  254  of the second signal interface  25  and the motherboard  200 . In other words, a first end  2541  of the pin segment  254  is connected to the fixture segment  253 , and a second end  2542  of the pin segment  254  is inserted into the motherboard  200 . 
     Please refer to  FIGS. 8˜11 .  FIG. 8  is a schematic assembled view illustrating an electrical receptacle according to a third embodiment of the present invention.  FIG. 9  is a schematic exploded view illustrating the electrical receptacle of the third embodiment.  FIG. 10  is a schematic exploded view illustrating the electrical receptacle of the third embodiment and taken along another viewpoint.  FIG. 11  is a schematic side view illustrating the electrical receptacle to be mounted on a motherboard according to the third embodiment of the present invention. 
     As shown in  FIGS. 8˜11 , the electrical receptacle  30  comprises a first plastic main body  31 , a plastic tongue plate  311 , a circuit board  32 , and a second plastic main body  33 . The first plastic main body  31  has a first docking space  371  and a second docking space  372 . The plastic tongue plate  311  is fixed on a sidewall of a bottom part  314  of the first plastic main body  31  and extended toward the front side. Moreover, the circuit board  32  is disposed under the plastic tongue plate  311 . 
     In this embodiment, the electrical receptacle  30  further comprises a metallic casing  38 , which is sheathed around the outer periphery of the combination of the first plastic main body  31  and the second plastic main body  33 . 
     In this embodiment, the plastic tongue plate  311  is suspended toward the front side. Moreover, no any other protrusion plate parallel with and separated from the plastic tongue plate  311  is arranged under the plastic tongue plate  311  to support the first plastic main body  31 . That is, two lateral walls  313  are disposed on the bottom part  314  of the first plastic main body  31  and extended toward the front side. Moreover, a shared profile  3131  mating with different signal interfaces of an electrical plug (see  FIG. 61 ) is located at the front peripheries of the two lateral walls  313 . Consequently, the two lateral walls  313  can support the first plastic main body  31  and provide the shared profile  3131  to achieve the all-in-one electrical receptacle. 
     From front to back, the signal interface structure segments of the first signal interface  34  (e.g. an eSATA signal interface) successively comprise a plurality of contact pads  341 , a plurality of extension wires  342 , a plurality of fixture segments  343 , and a plurality of pin segments  344 . From front to back, the signal interface structure segments of the second signal interface  35  (e.g. a USB 2.0 signal interface) successively comprise a plurality of contact resilience arm segments  351 , a plurality of extension segments  352 , a plurality of fixture segments  353 , and a plurality of pin segments  354 . That is, the USB 2.0 signal interface  35  also comprises a plurality of USB 2.0 metallic terminals. 
     The arrangements of the eSATA signal interface  34  and the USB 2.0 signal interface  35  are similar to the arrangements of the eSATA signal interface  14  and the USB 2.0 signal interface  15  of the first embodiment, and are not redundantly described herein. 
     In comparison with the pin segment  144  of the eSATA signal interface  14  of the first embodiment, the bending angle of the pin segment  344  of the eSATA signal interface  34  is relatively larger. Moreover, for complying with the USB 3.0 communication protocol, the electrical receptacle  30  of this embodiment further comprises a USB 3.0 signal interface  36 . That is, the four-terminal USB 2.0 signal interface  35  and the 5-terminal USB 3.0 signal interface  36  may collaboratively support the USB 3.0 communication protocol. 
     From front to back, the signal interface structure segments of the USB 3.0 signal interface  36  successively comprise a plurality of contact segments  361 , a plurality of extension segments  362 , a plurality of fixture segments  363 , and a plurality of pin segments (or welding segments)  364 . That is, the USB 3.0 signal interface  36  comprises a plurality of USB 3.0 metallic terminals. 
     In accordance with a key feature of the present invention, the second plastic main body  33  is a rear cover with a plurality of structure segment fixing spaces. For example, the structure segment fixing spaces are a plurality of fixing recesses  3311 ,  3312  with position-limiting structures (see  FIG. 10 ). The structure segment fixing space is used for accommodating and fixing the fixture segments  353  of the USB 3.0 signal interface  35  that are installed on the second plastic main body  33 . Moreover, the fixture segments  343  of the eSATA signal interface  34  are accommodated within and installed on the region between the first plastic main body  31  and the second plastic main body  33 . The fixture segments  363  of the USB 3.0 signal interface  36  are installed on the first plastic main body  31 . 
     For assembling the electrical receptacle  30 , the above components may be moved in the assembling directions S 31 ˜S 34  as shown in  FIG. 9  and  FIG. 10 . Firstly, the fixture segments  353  of the USB 2.0 signal interface  35  are previously installed on the second plastic main body  33  along the assembling direction S 31 . Then, after the USB 3.0 signal interface  36  is inserted and placed within the terminal recesses  3114  of the plastic tongue plate  311  along the assembling direction S 32 , the contact segments  361  of the USB 3.0 signal interface  36  are penetrated through a plurality of contact holes  3113  of the plastic tongue plate  311  to be exposed to the first docking space  371 . Then, the circuit board  32  is installed on the first plastic main body  31  along the assembling direction S 33 . Then, after the combination of the second plastic main body  35  and the USB 2.0 signal interface  35  is moved upwardly to be installed on the first plastic main body  31  along the assembling direction S 34 , and the contact resilience arm segments  351  of the USB 2.0 signal interface  35  are penetrated through the grooves  321  of the circuit board  32  and the slots  3112  of the plastic tongue plate  311 . After the metallic casing  38  is sheathed around the outer periphery of the combination of the first plastic main body  31  and the second plastic main body  33  along the assembling direction S 35 , the electrical receptacle  30  is assembled. 
     In this embodiment, the plastic tongue plate  311  and the circuit board  32  may be collaboratively defined as a composite tongue plate structure. The contact resilience arm segments  351  of the USB 2.0 signal interface  35  are located at the top side of the composite tongue plate structure and exposed to the first docking space  371 . Moreover, the contact pads  341  of the eSATA signal interface  34  are located at the bottom side of the composite tongue plate structure and exposed to the second docking space  372 . 
     Moreover, after the first plastic main body  31  and the second plastic main body  33  are combined together, the seven pin segments  344  of the eSATA signal interface  34  and the five contact segments  364  of the USB 3.0 signal interface  36  are accommodated within respective ones of twelve receiving holes  333  of the second plastic main body  33  (see  FIG. 9 ). It is noted that the four pin segments  354  of the USB 2.0 signal interface  35  are not accommodated within the second plastic main body  33 . 
     In this embodiment, the second plastic main body  33  (i.e. the rear cover) comprises a plurality of fixing recesses  3311 ,  3312  and a plurality of receiving holes  333 . Moreover, a sidewall  330  of the second plastic main body  33  (i.e. the rear cover) is exposed to or arranged beside the second docking space  372 . 
     Moreover, a motherboard  300  is shown in  FIG. 11  but not shown in  FIGS. 8˜10 . The motherboard  300  has a plurality of insertion holes  3001 ,  3002  and  3003 . The pin segments  344  of the first signal interface  34  (i.e. the eSATA signal interface), the pin segments  354  of the second signal interface  35  (i.e. the USB 2.0 signal interface) and the pin segments  364  of the USB 3.0 signal interface  36  are inserted into the insertion holes  3001 ,  3002  and  3003 , respectively. After the pin segments  344 ,  354  and  364  are welded to the insertion holes  3001 ,  3002  and  3003 , the electrical receptacle  30  is welded on the motherboard  300 . 
     Moreover, after the second signal interface  35  is fixed on the second plastic main body  33  (i.e. the rear cover), no additional structural member is arranged between the pin segments  354  of the second signal interface  35  and the motherboard  300 . In other words, a first end  3541  of the pin segment  354  is connected to the fixture segment  353 , and a second end  3542  of the pin segment  354  is inserted into the motherboard  300 . Moreover, after the first signal interface  34  is arranged between the first plastic main body  31  and the second plastic main body  33  and the third signal interface  36  is installed on first plastic main body  31 , the pin segments  344  and  364  are penetrated through the receiving holes  333  of the second plastic main body  33  (i.e. the rear cover), and then welded on the motherboard  300 . 
     The electrical receptacle of the third embodiment has benefits identical to those of the first embodiment. Moreover, since portions of the signal interface structure segments of the USB 2.0 signal interface  35  are previously distributed to the second plastic main body  33  and separated from the USB 3.0 signal interface  36  by a spacing interval, the signal interference between the USB 2.0 signal interface  35  and the USB 3.0 signal interface  36  will be minimized. 
       FIG. 12  is a schematic side view illustrating the electrical receptacle to be mounted on a motherboard according to a fourth embodiment of the present invention. As shown in  FIG. 12 , the electrical receptacle  40  comprises a first plastic main body  41 , a plastic tongue plate  411 , a circuit board  42 , and a second plastic main body  43 . The first plastic main body  41  has a first docking space  471  and a second docking space  472 . The plastic tongue plate  411  is fixed on a sidewall of a bottom part  414  of the first plastic main body  41  and extended toward the front side. Moreover, the circuit board  42  is disposed over the plastic tongue plate  411 . 
     From front to back, the signal interface structure segments of the first signal interface  44  (e.g. an eSATA signal interface) successively comprise a plurality of contact pads  441 , a plurality of extension wires, a plurality of fixture segments  443 , and a plurality of pin segments  444 . From front to back, the signal interface structure segments of the second signal interface  45  (e.g. a USB 2.0 signal interface) successively comprise a plurality of contact resilience arm segments  451 , a plurality of extension segments  452 , a plurality of fixture segments  453 , and a plurality of pin segments  454 . That is, the USB 2.0 signal interface  45  comprises a plurality of USB 2.0 metallic terminals. 
     From front to back, the signal interface structure segments of the third signal interface  46  (e.g. a USB 3.0 signal interface) successively comprise a plurality of contact segments  461 , a plurality of extension segments  462 , a plurality of fixture segments  463 , and a plurality of pin segments  464 . That is, the USB 3.0 signal interface  46  comprises a plurality of USB 3.0 metallic terminals. 
     In this embodiment, the eSATA signal interface  44  is installed on the top surface of the circuit board  42 . The extension segments  452 , the fixture segments  453  and the pin segments  454  of the USB 2.0 signal interface  45  are arranged beside the eSATA signal interface  44 . The contact resilience arm segments  451  are penetrated downwardly from the top surface of the circuit board  42  and through four grooves  421  of the circuit board  42  and four slots  4112  of the plastic tongue plate  411 , and exposed to the first docking space  471  beside the plastic tongue plate  411 . 
     In this embodiment, the circuit board  42  and the plastic tongue plate  411  may be collaboratively defined as a composite tongue plate structure. The contact pads  441  of the eSATA signal interface  44  are located at the top side of the composite tongue plate structure and exposed to the second docking space  472 . Moreover, the contact resilience arm segments  451  of the USB 2.0 signal interface  45  and the contact segments  461  of the third signal interface  46  are located at the bottom side of the composite tongue plate structure and exposed to the first docking space  471 . 
     Moreover, in this embodiment, a sidewall  430  of the second plastic main body  43  (i.e. the rear cover) is exposed to or arranged beside the second docking space  472 . 
     In this embodiment, the electrical receptacle  40  further comprises a metallic casing  48 , which is sheathed around the outer periphery of the combination of the first plastic main body  41  and the second plastic main body  43 . 
     In accordance with a key feature of the present invention, the second plastic main body  43  is a rear cover with a plurality of structure segment fixing spaces. For example, the structure segment fixing spaces are a plurality of fixing recesses with position-limiting structures (see also the third embodiment). The structure segment fixing spaces are used for accommodating and fixing the fixture segments  453  of the USB 2.0 signal interface  45  that are installed on the second plastic main body  43 . 
     Moreover, a motherboard  400  is shown in  FIG. 12 . The motherboard  400  has a plurality of insertion holes  4001 ,  4002  and  4003 . The pin segments  444  of the first signal interface  44  (i.e. the eSATA signal interface), the pin segments  454  of the second signal interface  45  (i.e. the USB 2.0 signal interface) and the pin segments  464  of the USB 3.0 signal interface  46  are inserted into the insertion holes  4001 ,  4002  and  4003 , respectively. After the pin segments  444 ,  454  and  464  are welded to the insertion holes  4001 ,  4002  and  4003 , the electrical receptacle  40  is welded on the motherboard  400 . 
     Moreover, after the second signal interface  45  is fixed on the second plastic main body  43  (i.e. the rear cover), no additional structural member is arranged between the pin segments  454  of the second signal interface  45  and the motherboard  400 . In other words, a first end  4541  of the pin segment  454  is connected to the fixture segment  453 , and a second end  4542  of the pin segment  454  is inserted into the motherboard  400 . 
     Hereinafter, some variants of the electrical receptacle of the present invention will be illustrated in more details. The functions or arrangements which are similar to the above embodiments will not be described herein. 
       FIG. 13  is a schematic side view illustrating the electrical receptacle according to a fifth embodiment of the present invention. Like the third embodiment, the electrical receptacle  50  as shown in  FIG. 13  comprises a first plastic main body  51 , a plastic tongue plate  511 , a circuit board  52 , a second plastic main body  53 , a first signal interface  54  (e.g. an eSATA signal interface), a second signal interface  55  (e.g. a USB 2.0 signal interface), and a third signal interface  56  (e.g. a USB 3.0 signal interface). The first plastic main body  51  has a first docking space  571  and a second docking space  572 . The plastic tongue plate  511  is fixed on a sidewall of a bottom part of the first plastic main body  51  and extended toward the front side. Moreover, the circuit board  52  is disposed under the plastic tongue plate  511 . 
     In this embodiment, the fixture segments  563  of the USB 3.0 signal interface  56  are installed on the second plastic main body  53 . Consequently, for assembling the electrical receptacle  50 , the circuit board  52  and the second plastic main body  53  with the USB 3.0 signal interface  56  are moved forwardly to be combined with the first plastic main body  51 . 
     Of course, after the USB 3.0 signal interface  56  is fixed on the second plastic main body  53 , no additional structural member is arranged between the pin segments  564  of the USB 3.0 signal interface  56  and the motherboard (not shown). 
       FIG. 14  is a schematic side view illustrating the electrical receptacle according to a sixth embodiment of the present invention. Like the fifth embodiment, the electrical receptacle  60  as shown in  FIG. 14  comprises a first plastic main body  61 , a plastic tongue plate  611 , a circuit board  62 , a second plastic main body  63 , a first signal interface  64  (e.g. an eSATA signal interface), a second signal interface  65  (e.g. a USB 2.0 signal interface), and a third signal interface  66  (e.g. a USB 3.0 signal interface). The first plastic main body  561  has a first docking space  671  and a second docking space  672 . The plastic tongue plate  611  is fixed on a sidewall of a bottom part of the first plastic main body  61  and extended toward the front side. Moreover, the circuit board  62  is disposed over the plastic tongue plate  611 . Like the fifth embodiment, the fixture segments  663  of the USB 3.0 signal interface  66  are installed on the second plastic main body  63 . Consequently, for assembling the electrical receptacle  60 , the circuit board  62  and the second plastic main body  53  with the USB 3.0 signal interface  66  are moved forwardly to be combined with the first plastic main body  61 . 
     Of course, after the USB 3.0 signal interface  66  is fixed on the second plastic main body  63 , no additional structural member is arranged between the pin segments  664  of the USB 3.0 signal interface  66  and the motherboard (not shown). 
     The following embodiments will be illustrated by referring to the electrical receptacle with the composite tongue plate structure including a fixed plastic tongue plate or a removable plastic tongue plate and at least one circuit board. In addition, each signal interface unit of any signal interface is composed of three structure segments, including a metallic contact part (e.g. a contact resilience arm segment or a contact pad or a contact segment), an extension segment (or an extension wire), and a pin segment. 
       FIG. 15  is a schematic side view illustrating the electrical receptacle to be mounted on a motherboard according to a seventh embodiment of the present invention. Except for the following items, the other components and mechanisms of the electrical receptacle of this embodiment are similar to those of the fourth embodiment, and are not redundantly described herein. 
     In this embodiment, the extension segments  7072  of the second signal interface  707  of the electrical receptacle  70  are previously installed and fixed on the rear cover  705 . In comparison with the fourth embodiment, the first signal interface  706  and the third signal interface  708  are welded on a first surface  7041  and a second surface  7042  of the circuit board  706 , respectively. A process of assembling the electrical receptacle  70  will be illustrated as follows. Firstly, the circuit board  704  is accommodated within the receiving space of the tongue plate  702 , which is installed on the plastic main body  701 . That is, the circuit board  704  with the first signal interface  706  and the third signal interface  708  welded thereon is accommodated within the receiving space of the tongue plate  702 . Then, the rear cover  7055  along with the second signal interface  707  is installed on the plastic main body  701 . After the metallic casing  709  is sheathed around the outer periphery of the plastic main body  701 , the electrical receptacle  70  is assembled. 
     In this embodiment, the USB 2.0 signal interface  707  is installed on the rear cover  705 . In addition, a first end  70731  of the pin segment  7073  of the USB 2.0 signal interface  707  is connected to the extension segment  7072 , and a second end  70732  of the pin segment  7073  is inserted into the motherboard  700 . Moreover, no additional structural member is arranged between the pin segments  7073  of the USB 2.0 signal interface  707  and the motherboard  700 . Moreover, the pin segments  7063  of the first signal interface  706 , the pin segments  7073  of the second signal interface  707  and the pin segments  7083  of the USB 3.0 signal interface  708  are inserted into the insertion holes  7001 ,  7002  and  7003  of the motherboard  700 , respectively. 
       FIG. 16  is a schematic side view illustrating the electrical receptacle according to an eighth embodiment of the present invention. Except for the following items, the other components and mechanisms of the electrical receptacle of this embodiment are similar to those of the seventh embodiment, and are not redundantly described herein. 
     In comparison with the seventh embodiment, the circuit board  714  of the electrical receptacle  71  has a plurality of conductive holes  7144  running through the first surface  7141  and the second surface  7142  of the circuit board  714 . The contact pads  7161  and the extension wires  7161  of the first signal interface  716  are disposed on the second surface  7142  of the circuit board  714  or accommodated within the second docking space  7112  beside the second surface  7142  of the circuit board  714 . The pin segments  7163  of the first signal interface  716  are welded on the respective soldering regions of the conductive holes  7144  at the first surface  7141  of the circuit board  714 . Moreover, the conductive holes  7144  run through the first surface  7141  and the second surface  7142  of the circuit board  714 , and are electrically connected with the extension wires  7162 . In this embodiment, the pin segments  7163  of the first signal interface  716  and respective pin segments  7183  of the third signal interface  718  are shared with each other. 
     A portion of the signal interface structure segments of the second signal interface  717  (e.g. the last half of the segment  7172 ) and the contact pad  7161  and the extension wire  7162  of the first signal interface  716  are arranged beside each other and located at the same side of the circuit board  714  (i.e. disposed on the second surface  7142  of the circuit board  714 , or disposed within the second docking space  7112  beside the second surface  7142  of the circuit board  714 ). Moreover, another portion of the signal interface structure segments of the second signal interface  717  (e.g. the first half of the segment  7172 ) and the contact pad  7181  and the extension wire  7182  of the third signal interface  718  are arranged beside each other and located at the same side of the circuit board  714  (i.e. disposed on the first surface  7141  of the circuit board  714 , or disposed within the first docking space  7111  beside the first surface  7141  of the circuit board  714 ). 
     In this embodiment, the extension segments  7072  of the second signal interface  717  are also previously installed and fixed on the rear cover  715 . 
       FIG. 17  is a schematic side view illustrating the electrical receptacle according to a ninth embodiment of the present invention. Except for the following items, the other components and mechanisms of the electrical receptacle of this embodiment are similar to those of the seventh embodiment, and are not redundantly described herein. 
     In comparison with the seventh embodiment, the second signal interface  727  of the electrical receptacle  72  is directly installed on the plastic main body  721 . Moreover, the second signal interface  727  is arranged between the tongue plate  722  and the circuit board  724 . Consequently, the second signal interface  727  is not penetrated through the grooves  7243  of the circuit board  724 , but only penetrated through the slots  7223  of the tongue plate  722  to be exposed to the first docking space  7211 . 
     Moreover, the contact pads  7281  and the extension wires  7282  of the third signal interface  728  are disposed on the circuit board  724 . The pin segments  7283  of the third signal interface  728  are welded on the extension wires  7282  which are disposed on the circuit board  724 . 
       FIG. 18  is a schematic side view illustrating the electrical receptacle according to a tenth embodiment of the present invention. Except for the following items, the other components and mechanisms of the electrical receptacle of this embodiment are similar to those of the eighth embodiment, and are not redundantly described herein. 
     In comparison with the eighth embodiment, the second signal interface  737  of the electrical receptacle  73  is directly installed on the tongue plate  732  of the plastic main body  731 . Moreover, the second signal interface  737  is arranged between the tongue plate  732  and the circuit board  734 . Consequently, the second signal interface  737  is not penetrated through the grooves  7343  of the circuit board  734 , but only penetrated through the slots  7323  of the tongue plate  732  to be exposed to the first docking space  7311 . 
     Moreover, the contact pads  7361  and the extension wires  7362  of the first signal interface  736  are disposed on the second surface  7342  of the circuit board  734 , or accommodated within the second docking space  7312  beside the second surface  7342  of the circuit board  734 . The pin segments  7363  of the first signal interface  736  are welded on respective soldering regions of the conductive holes  7344  at the first surface  7373  of the circuit board  734 . Moreover, the conductive holes  7344  run through the first surface  7373  and the second surface  7342  of the circuit board  734 , and are electrically connected with the extension wires  7362 . In this embodiment, the pin segments  7363  of the first signal interface  736  and respective pin segments  7383  of the third signal interface  738  are shared with each other. 
     The second signal interface  737  and the pin segment  7363  of the first signal interface  736  are arranged beside each other and located at the same side of the circuit board  734  (i.e. disposed on the first surface  7373  of the circuit board  734 , or disposed within the first docking space  7311  beside the first surface  7373  of the circuit board  734 ). Moreover, the second signal interface  737  and the contact pad  7381  and the extension wire  7382  of the third signal interface  738  are arranged beside each other and exposed to the same docking space (i.e. the first docking space  7311 ). 
       FIG. 19  is a schematic side view illustrating the electrical receptacle to be mounted on a motherboard according to an eleventh embodiment of the present invention. Except for the following items, the other components and mechanisms of the electrical receptacle of this embodiment are similar to those of the fourth embodiment, and are not redundantly described herein. 
     In comparison with the fourth embodiment, the rear end of the extension segment  7482  and the pin segment  7483  of the third signal interface  748  are previously installed on the rear cover  745 . That is, the rear cover  745  of the electrical receptacle  74  further comprises a plurality of fixing recesses  7452  for previously accommodating and fixing the extension segment  7482  of the third signal interface  748 . Alternatively, the second signal interface  747  is not necessarily installed on the rear cover  745  or the circuit board  744 . For example, the extension segments  7472  of the second signal interface  747  are installed on the plastic main body  741 , and the pin segments  7473  are penetrated through the rear cover  745 . 
     After the third signal interface  748  is fixed on the rear cover  745 , no additional structural member is arranged between the pin segment  7483  of the third signal interface  748  and the motherboard  740 . In addition, a first end  74831  of the pin segment  7483  of the third signal interface  748  is connected to the extension segment  7482 , and a second end  74832  of the pin segment  7483  is inserted into the motherboard  700 . Moreover, the pin segments  7463  of the first signal interface  746 , the pin segments  7473  of the second signal interface  747  and the pin segments  7483  of the third signal interface  748  are inserted into the insertion holes  7401 ,  7402  and  7403  of the motherboard  740 , respectively. 
     In this embodiment, the fixed plastic tongue plate  742  and the circuit board  744  are collaboratively defined as a composite tongue plate structure. The contact resilience arm segments  7471  of the second signal interface  747  are penetrated through the slots (not shown) of the fixed plastic tongue plate  742  and the grooves (not shown) of the circuit board  744 . 
       FIG. 20  is a schematic exploded view illustrating an electrical receptacle according to a twelfth embodiment of the present invention.  FIG. 21  is a schematic exploded view illustrating the electrical receptacle of the twelfth and taken along another viewpoint. Except for the following items, the other components and mechanisms of the electrical receptacle of this embodiment are similar to those of the third embodiment, and are not redundantly described herein. 
     In comparison with the third embodiment, the plastic tongue plate  753  of the electrical receptacle  75  is a removable plastic tongue plate. The plastic tongue plate  753  is integrally formed with the rear cover  755 . Moreover, the extension segments  7572  of the second signal interface  757  are previously accommodated within the fixing recesses  7512  of the plastic main body  751 , but not installed on the circuit board  754 . 
     Moreover, the plastic main body  751  has a thin bottom part  7515 , and a plurality of fixing holes  7511 ,  7513  and a plurality of fixing recesses  7512  are formed in the bottom part  7515  of the plastic main body  751 . Two lateral walls  7515  are disposed on the thin bottom part  7514  of the plastic main body  751  and extended toward the front side. Moreover, a shared profile  75151  mating with various signal interfaces of an electrical plug (see  FIG. 61 ) is located at the front peripheries of the two lateral walls  7515 . Consequently, the two lateral walls  7515  can support the plastic main body  751  and provide the shared profile  75151  to achieve the all-in-one electrical receptacle. 
     In this embodiment, the circuit board  754  with the first signal interface  756  is receiving within a receiving space  7531  of the removable plastic tongue plate  753 . The third signal interface  758  is accommodated within the terminal recesses  7532  of the removable plastic tongue plate  753 . During the process of assembling the electrical receptacle  75 , the pin segments  7563  of the first signal interface  756  and the pin segments  7583  of the third signal interface  758  are accommodated within the receiving holes  7511  and  7513  of the plastic main body  751 , and then these pin segments are welded on a motherboard (not shown). 
     In this embodiment, the removable plastic tongue plate  753  and the circuit board  754  are collaboratively defined as the composite tongue plate structure. The contact resilience arm segments  7571  of the second signal interface  757  are penetrated through the slots  7533  of the removable plastic tongue plate  753  and the grooves  7543  of the circuit board  754 . 
     In this embodiment, the contact resilience arm segments  7571  of the second signal interface  75  are located at the top side of the composite tongue plate structure, and the contact segments  7581  of the third signal interface  758  and the contact pads  5611  of the eSATA signal interface  756  are located at the bottom side of the composite tongue plate structure. 
     Moreover, a sidewall  7550  of the rear cover  755  is exposed to or arranged beside at least one docking space  759 . 
     Of course, after the second signal interface  757  is fixed on the plastic main body  751 , no additional structural member is arranged between the pin segments  7573  of the second signal interface  757  and the motherboard (not shown). 
     Moreover, the receiving holes  7511  and  7513  of the plastic main body  751  are arranged between the pin segments  7563 ,  7583  of the first signal interface  756  and the third signal interface  758  and the motherboard (not shown). 
       FIG. 22  is a schematic exploded view illustrating an electrical receptacle according to a thirteenth embodiment of the present invention.  FIG. 23  is a schematic exploded view illustrating the electrical receptacle of the thirteenth and taken along another viewpoint. Except for the following items, the other components and mechanisms of the electrical receptacle of this embodiment are similar to those of the third embodiment, and are not redundantly described herein. 
     In comparison with the third embodiment, the plastic tongue plate  763  of the electrical receptacle  76  is a removable plastic tongue plate. Moreover, the plastic tongue plate  763  is an individual component to be combined with the plastic main body  761 . That is, the plastic tongue plate  763  is not extended from a sidewall of the bottom part  7614  of the plastic main body  761 . 
     In this embodiment, a first signal interface  766  is installed on the circuit board  764 . The removable plastic tongue plate  763  and the circuit board  766  are collaboratively defined as the composite tongue plate structure. Moreover, the contact resilience arm segments  7671  of the second signal interface  767  are penetrated through the slots  7633  of the removable plastic tongue plate  763  and the grooves  7643  of the circuit board  764 . Moreover, the third signal interface  768  is accommodated within the terminal recesses  7632  of the removable plastic tongue plate  763 . 
     The following embodiments will be illustrated by referring to the electrical receptacle with the composite tongue plate structure including two plastic tongue plates, wherein each of the plastic tongue plates is a fixed plastic tongue plate or a removable plastic tongue plate. In addition, each signal interface unit of any signal interface is composed of three structure segments, including a metallic contact part (e.g. a contact resilience arm segment or a contact pad or a contact segment), an extension segment (or an extension wire), and a pin segment. 
       FIG. 24  is a schematic exploded view illustrating an electrical receptacle according to a fourteenth embodiment of the present invention.  FIG. 25  is a schematic exploded view illustrating the electrical receptacle of the fourteenth and taken along another viewpoint. Except for the following items, the other components and mechanisms of the electrical receptacle of this embodiment are similar to those of the above embodiments, and are not redundantly described herein. 
     In comparison with the first embodiment, the electrical receptacle  77  of the fourteenth embodiment further comprises a removable plastic tongue plate  773  to replace the circuit board. Moreover, the removable plastic tongue plate  773  is integrally formed with the rear cover  775 . The first signal interface  776  and the second signal interface  777  are both accommodated within the removable plastic tongue plate  773  and the rear cover  775 . The extension segments  7762  of the first signal interface  776  and the extension segments  7772  of the second signal interface  777  are previously accommodated and fixed within the fixing recesses  7751  and  7732 , which are formed in the combined structure of the removable plastic tongue plate  773  and the rear cover  775 . 
     After the first signal interface  776  and the second signal interface  777  are fixed on the combined structure of the removable plastic tongue plate  773  and the rear cover  775 , no additional structural member is arranged between the pin segments  7763 ,  7773  and the motherboard (not shown). Moreover, the first signal interface  776  and the second signal interface  777  are respectively conductive terminal groups. The conductive terminals of each conductive terminal group are separated from each other and not electrically with each other. 
     In this embodiment, the fixed plastic tongue plate  772  and the removable plastic tongue plate  773  are collaboratively defined as the composite tongue plate structure. The removable plastic tongue plate  773  is accommodated within a receiving space  7721  of the fixed plastic tongue plate  772 . Moreover, the contact resilience arm segments  7771  of the second signal interface  777  are penetrated through the slots  7723  of the fixed plastic tongue plate  772  and the slots  7733  of the removable plastic tongue plate  773 . 
     In this embodiment, the first signal interface  776  is an eSATA signal interface, and the second signal interface  777  is a USB 2.0 signal interface. Consequently, the metallic contact part (i.e. the contact resilience arm segments  7771 ) of the second signal interface  777  is located at the top side of the composite tongue plate structure, and the metallic contact part (i.e. the contact segments  7761 ) is located at the bottom side of the composite tongue plate structure. 
       FIG. 26  is a schematic side view illustrating the electrical receptacle to be mounted on a motherboard according to a fifteenth embodiment of the present invention. Except for the following items, the other components and mechanisms of the electrical receptacle of this embodiment are similar to those of the third and fourteenth embodiments, and are not redundantly described herein. 
     In comparison with the fourteenth embodiment, the electrical receptacle  78  of this embodiment further comprises a removable plastic tongue plate  783  to replace the circuit board. Moreover, the removable plastic tongue plate  783  is integrally formed with the rear cover  785 . The first signal interface  786  and the second signal interface  787  are both accommodated within the within the fixing recesses (not shown, but may be referred to  FIGS. 24 and 25 ), which are formed in the combined structure of the removable plastic tongue plate  783  and the rear cover  785 . The third signal interface  788  is accommodated within the plastic main body  781  and the fixed plastic tongue plate  782 , which is extended from the plastic main body  781 . 
     In this embodiment, the fixed plastic tongue plate  782  and the removable plastic tongue plate  783  are collaboratively defined as the composite tongue plate structure. Moreover, the contact resilience arm segments  7871  of the second signal interface  787  are penetrated through the slots  7823  of the fixed plastic tongue plate  782  and the slots  7833  of the removable plastic tongue plate  783 . 
     Moreover, the rear cover  785  has a plurality of receiving holes  7851  for accommodating the pin segments  7833  of the third signal interface  788 . The pin segments  7863  of the first signal interface  786  and the pin segments  7873  of the second signal interface  787  are bent downwardly from the bottom side and the top side of the combined structure of the removable plastic tongue plate  783  and the rear cover  785 , respectively. 
     After the first signal interface  786  and the second signal interface  787  are fixed on the combined structure of the removable plastic tongue plate  783  and the rear cover  785 , no additional structural member is arranged between the pin segments  7863 ,  7873  and the motherboard  780 . Moreover, the pin segments  7863  of the first signal interface  786 , the pin segments  7873  of the second signal interface  787  and the pin segments  7883  of the third signal interface  788  accommodated within the receiving holes  7851  are inserted into the insertion holes  7801 ,  7802  and  7803  of the motherboard  780 , respectively. 
     Moreover, the first signal interface  786 , the second signal interface  787  and the third signal interface  788  are respectively conductive terminal groups. The conductive terminals of each conductive terminal group are separated from each other and not electrically with each other. 
       FIG. 27  is a schematic exploded view illustrating an electrical receptacle according to a sixteenth embodiment of the present invention. Except for the following items, the other components and mechanisms of the electrical receptacle of this embodiment are similar to those of the fifteenth embodiment, and are not redundantly described herein. 
     In comparison with the fifteenth embodiment, the removable plastic tongue plate  799  and the rear cover  795  of the electrical receptacle  79  of this embodiment are both individual components. The extension segments  7972  of the second signal interface  797  are previously installed and fixed on the rear cover  795 . Moreover, the first signal interface  796  is accommodated within the removable plastic tongue plate  799 . Moreover, the third signal interface  798  is accommodated within the fixed plastic tongue plate  792 . 
     In this embodiment, the removable plastic tongue plate  799  and the fixed plastic tongue plate  782  are collaboratively defined as the composite tongue plate structure. Moreover, the contact resilience arm segments  7971  of the second signal interface  797  are penetrated through the slots  7923  of the fixed plastic tongue plate  792  and the slots  7993  of the removable plastic tongue plate  799 . 
     The following embodiments will be illustrated by referring to the electrical receptacle with a composite tongue plate structure including two plastic tongue plates. One of these two plastic tongue plates is a fixed plastic tongue plate, and the other is a removable plastic insert molding tongue plate with at least one signal interface structure segment. In addition, each signal interface unit of any signal interface is composed of three structure segments, including a metallic contact part (e.g. a contact resilience arm segment or a contact pad or a contact segment), an extension segment (or an extension wire), and a pin segment 
       FIG. 28  is a schematic exploded view illustrating an electrical receptacle according to a seventeenth embodiment of the present invention.  FIG. 29  is a schematic exploded view illustrating the electrical receptacle of the seventeenth and taken along another viewpoint. Except for the following items, the other components and mechanisms of the electrical receptacle of this embodiment are similar to those of the first embodiment, and are not redundantly described herein. 
     In comparison with the first embodiment, the electrical receptacle  80  of this embodiment further comprises a removable plastic insert molding tongue plate  809  to replace the circuit board. The first signal interface  806  and the removable plastic insert molding tongue plate  809  are combined together by a plastic insert molding process. Moreover, the extension segments  8072  of the second signal interface  807  may be previously installed and fixed on the rear cover  805 . 
     In this embodiment, the fixed plastic tongue plate  802  and the removable plastic insert molding tongue plate  809  are collaboratively defined as the composite tongue plate structure. Moreover, the contact resilience arm segments  8071  of the second signal interface  807  are penetrated through the slots  8023  of the fixed plastic tongue plate  802  and the slots  8093  of the removable plastic tongue plate  809 . 
       FIG. 30  is a schematic exploded view illustrating an electrical receptacle according to an eighteenth embodiment of the present invention.  FIG. 31  is a schematic exploded view illustrating the electrical receptacle of the eighteenth and taken along another viewpoint. Except for the following items, the other components and mechanisms of the electrical receptacle of this embodiment are similar to those of the third embodiment, and are not redundantly described herein. 
     In comparison with the third embodiment, the electrical receptacle  81  of this embodiment further comprises a removable plastic insert molding tongue plate  819  to replace the circuit board. The first signal interface  816 , the third signal interface  818  and the removable plastic insert molding tongue plate  819  are combined together by a plastic insert molding process. Moreover, the extension segments  8172  of the second signal interface  817  may be previously installed and fixed on the rear cover  815 . 
     In this embodiment, the fixed plastic tongue plate  812  and the removable plastic insert molding tongue plate  819  are collaboratively defined as the composite tongue plate structure. Moreover, the contact resilience arm segments  8171  of the second signal interface  817  are penetrated through the slots  8123  of the fixed plastic tongue plate  812  and the slots  8193  of the removable plastic tongue plate  819 . 
       FIG. 32  is a schematic exploded view illustrating an electrical receptacle according to a nineteenth embodiment of the present invention.  FIG. 33  is a schematic exploded view illustrating the electrical receptacle of the nineteenth and taken along another viewpoint. Except for the following items, the other components and mechanisms of the electrical receptacle of this embodiment are similar to those of the eighteenth embodiment, and are not redundantly described herein. 
     In comparison with the eighteenth embodiment, the first signal interface  826  and the third signal interface  828  have shared pin segments. The first signal interface  826 , the third signal interface  828  and the removable plastic insert molding tongue plate  829  are combined together by a plastic insert molding process. 
     In this embodiment, the fixed plastic tongue plate  822  and the removable plastic insert molding tongue plate  829  are collaboratively defined as the composite tongue plate structure. Moreover, the contact resilience arm segments  8271  of the second signal interface  827  are penetrated through the slots  8223  of the fixed plastic tongue plate  822  and the slots  8293  of the removable plastic tongue plate  829 . Moreover, the extension segments  8272  of the second signal interface  827  may be previously installed and fixed on the rear cover  825 . 
     The following embodiments will be illustrated by referring to the electrical receptacle with the composite tongue plate structure complying with a single communication protocol (e.g. the USB 3.0 communication protocol). Consequently, the electrical plug may be inserted into the electrical receptacle in a forward or reverse docking direction. 
       FIG. 34  is a schematic side view illustrating an electrical receptacle to be mounted on a motherboard according to a twentieth embodiment of the present invention. As shown in  FIG. 34 , the electrical receptacle  83  comprises a plastic main body  831  (also referred as a first insulating main body), a circuit board  834 , two 5-terminal USB 3.0 signal interfaces  8380 ,  838 , and two 4-terminal USB 2.0 signal interfaces  8370 ,  837  (i.e. the total terminal number is 8). The first plastic main body  831  has a first docking space  8391  and a second docking space  8392 . The USB 3.0 signal interfaces  8380  and  838  are located at the top side  8341  and the bottom side  8342  of the circuit board  834 , respectively. The USB 2.0 signal interfaces  8370  and  837  are located at the top side  8341  and the bottom side  8342  of the circuit board  834 , respectively. 
     In this embodiment, the tongue plate  832  is fixed on a sidewall of a bottom part of the plastic main body  831  and extended toward the front side. A receiving space  8320  for accommodating the circuit board  834  is arranged between the top surface and the bottom surface of the tongue plate  832 . 
     Moreover, the extension segments  8372  of the USB 2.0 signal interface  837  are previously installed on and fixed on the rear cover  835  (also referred as a second insulating main body). Consequently, for assembling the electrical receptacle  83 , the rear cover  835  with the 4-terminal USB 2.0 signal interface  837  is moved upwardly to be combined with the plastic main body  831 . 
     In the following embodiments, the composite tongue plate structure is applied to the electrical receptacle with the signal interfaces other than the eSATA signal interface and the USB signal interface. It is to be noted that the following descriptions of preferred embodiments of this invention are presented herein for purpose of illustration and description only. 
       FIG. 35  is a schematic side view illustrating an electrical receptacle to be mounted on a motherboard according to a twenty-first embodiment of the present invention. The electrical receptacle  84  is an electrical receptacle complying with a high definition multimedia interface (HDMI) protocol. In this embodiment, a fixed plastic tongue plate  842  is integrally formed with the plastic main body  841 . In addition, a removable plastic tongue plate  843  is integrally formed with the rear cover  845 . That is, the fixed plastic tongue plate  842  and the removable plastic insert molding tongue plate  843  are collaboratively defined as the composite tongue plate structure. Moreover, a first docking space  8491  and a second docking space  8492  are located at the top side and the bottom side of the composite tongue plate structure, respectively. A sidewall  8450  of the rear cover  845  is exposed to or arranged beside the first docking space  8491 . 
     Moreover, a HDMI signal interface  846  is installed and fixed on the fixed plastic tongue plate  842 , and another HDMI signal interface  846  is installed and fixed on the removable plastic insert molding tongue plate  843 , which is integrally formed with the rear cover  845 . Consequently, the HDMI signal interface structure segment (at least including a metallic contact part and an extension segment) is installed on each of the top side and the bottom side of the composite tongue plate structure. 
     Of course, no additional structural member is arranged between the pin segments of the HDMI signal interface  846  and the motherboard (not shown). 
       FIG. 36  is a schematic side view illustrating an electrical receptacle according to a twenty-second embodiment of the present invention. The electrical receptacle  85  is an electrical receptacle complying with a display port protocol. In this embodiment, a fixed plastic tongue plate  852  is integrally formed with the plastic main body  851 . In addition, a removable plastic tongue plate  853  is integrally formed with the rear cover  855 . That is, the fixed plastic tongue plate  852  and the removable plastic insert molding tongue plate  853  are collaboratively defined as the composite tongue plate structure. Moreover, a first docking space  8591  and a second docking space  8592  are located at the top side and the bottom side of the composite tongue plate structure, respectively. A sidewall  8550  of the rear cover  855  is exposed to or arranged beside the first docking space  8591 . 
     Moreover, a display port signal interface  856  is installed and fixed on the fixed plastic tongue plate  852 , and another display port signal interface  856  is installed and fixed on the removable plastic insert molding tongue plate  853 , which is integrally formed with the rear cover  855 . Consequently, the display port signal interface structure segment (at least including a metallic contact part and an extension segment) is installed on each of the top side and the bottom side of the composite tongue plate structure. 
     Of course, no additional structural member is arranged between the pin segments of the display port signal interface  856  and the motherboard (not shown). 
     The following embodiments will be illustrated by referring to the electrical receptacle with the single tongue plate structure. The single tongue plate structure is a fixed plastic tongue plate or a removable plastic tongue plate. Moreover, the single tongue plate structure may be a plastic tongue plate or a plastic insert molding tongue plate. 
       FIG. 37  is a schematic side view illustrating an electrical receptacle to be mounted on a motherboard according to a twenty-third embodiment of the present invention. Except for the following items, the other components and mechanisms of the electrical receptacle of this embodiment are similar to those of the first embodiment, and are not redundantly described herein. 
     In comparison with the first embodiment, the electrical receptacle  86  of this embodiment has no circuit board. Consequently, the tongue plate structure  862  is a single fixed plastic tongue plate. In addition, the tongue plate structure  862  is fixed on a sidewall of a bottom part  8614  of the plastic main body  861  and extended toward the front side. Moreover, a first docking space  8691  and a second docking space  8692  are located at the top side and the bottom side of the tongue plate structure  862 , respectively. 
     The electrical receptacle  86  further comprises a rear cover  865 . A second signal interface  867  is previously installed and fixed on the rear cover  865 . Moreover, the contact resilience arm segments  8671  of the second signal interface  867  are penetrated through the slots  8623  of the tongue plate structure  862 . The sidewall  8650  of the rear cover  865  is exposed to or arranged beside the second docking space  8692 . 
     Moreover, the contact segments  8661  and the front ends of the extension segments  8662  of the first signal interface  866  are fixed on the plastic main body  861 . The pin segments  8663  of the first signal interface  866  are accommodated within the receiving holes  8651  of the rear cover  865 . 
     In this embodiment, the first signal interface  866  is an eSATA signal interface, and the second signal interface  867  is a USB 2.0 signal interface. Consequently, the metallic contact part (i.e. the contact segments  8661 ) of the first signal interface  866  is located at the bottom side of the single tongue plate structure, and the metallic contact part (i.e. contact resilience arm segments  8671 ) of the second signal interface  867  is located at the top side of the single tongue plate structure. Moreover, the contact resilience arm segments  8671  and the extension segments  8672  of the second signal interface  867  are penetrated through the slots  8623  of the tongue plate structure  862  and exposed to the first docking space  8691 . 
     Moreover, the first signal interface  866  and the second signal interface  867  are respectively conductive terminal groups. The conductive terminals of each conductive terminal group are separated from each other and not electrically with each other. Moreover, no additional structural member is arranged between the pin segments  8673  of the second signal interface  867  and the motherboard  860 . In other words, a first end  86731  of the pin segment  8673  is connected to the fixture segment  8672 , and a second end  86732  of the pin segment  8673  is inserted into the motherboard  860 . Moreover, the pin segments  8663  of the first signal interface  866  and the pin segments  8673  of the second signal interface  867  are inserted into the insertion holes  8601  and  8602  of the motherboard  860 , respectively. 
       FIG. 38  is a schematic exploded view illustrating an electrical receptacle according to a twenty-fourth embodiment of the present invention.  FIG. 39  is a schematic exploded view illustrating the electrical receptacle of the twenty-fourth and taken along another viewpoint. Except for the following items, the other components and mechanisms of the electrical receptacle of this embodiment are similar to those of the third embodiment, and are not redundantly described herein. 
     In comparison with the third embodiment, the electrical receptacle  87  of this embodiment has no circuit board. Consequently, the tongue plate structure  872  is a single fixed plastic tongue plate. In addition, the tongue plate structure  872  is fixed on a sidewall of a bottom part  8714  of the plastic main body  871  and extended toward the front side. Moreover, a first docking space  8791  and a second docking space  8792  are located at the top side and the bottom side of the tongue plate structure  872 , respectively. 
     The electrical receptacle  87  further comprises a rear cover  875 . A second signal interface  877  (e.g. a USB 2.0) is previously installed and fixed on the rear cover  875 . Moreover, the contact resilience arm segments  8771  of the second signal interface  877  are penetrated through the slots  8723  of the tongue plate structure  872 . The sidewall  8750  of the rear cover  875  is exposed to or arranged beside the second docking space  8792 . 
     Moreover, the contact segments  8761  of the first signal interface  876  (e.g. an eSATA signal interface), the contact segments  8781  of the third signal interface  878  (e.g. a USB 3.0 signal interface), the front ends of the extension segments  8762  of the first signal interface  876  and the front ends of the extension segments  8782  of the third signal interface  878  are fixed on the plastic main body  871  and the tongue plate structure  872  through the terminal recesses  8732 . Moreover, the pin segments  8763  of the first signal interface  876  and the pin segments  8783  of the third signal interface  878  are accommodated within the receiving holes  8751  of the rear cover  875 . Moreover, the extension segments  8782  of the third signal interface  878  are previously accommodated and fixed within the fixing recesses  8572  of the rear cover  875 . That is, the rear cover  875  comprises both the receiving holes  8751  and the fixing recesses  8572 . 
     Moreover, the first signal interface  876 , the second signal interface  877  and the third signal interface  878  are respectively conductive terminal groups. The conductive terminals of each conductive terminal group are separated from each other and not electrically with each other. Moreover, no additional structural member is arranged between the pin segments  8773  of the second signal interface  877  and the motherboard (not shown). 
       FIG. 40  is a schematic side view illustrating an electrical receptacle according to a twenty-fifth embodiment of the present invention. Except for the following items, the other components and mechanisms of the electrical receptacle of this embodiment are similar to those of the twenty-fourth embodiment, and are not redundantly described herein. 
     In comparison with the twenty-fourth embodiment, the extension segments  8882  of the third signal interface  888  (e.g. a USB 3.0 signal interface) are previously installed and fixed on the rear cover  885  of the electrical receptacle  88  of this embodiment. In addition, the first signal interface  886  (e.g. an eSATA signal interface) and the second signal interface  887  (e.g. a USB 2.0 signal interface) are installed on the plastic main body  881 . Moreover, the contact resilience arm segments  8871  of the second signal interface  887  are penetrated through the slots  8823  of the tongue plate structure  882 . 
       FIG. 41  is a schematic side view illustrating an electrical receptacle according to a twenty-sixth embodiment of the present invention. Except for the following items, the other components and mechanisms of the electrical receptacle of this embodiment are similar to those of the twenty-third embodiment, and are not redundantly described herein. 
     In comparison with the twenty-third embodiment, the extension segments  8972  of the second signal interface  872  are previously installed and fixed on the rear cover  895  of the electrical receptacle  89  of this embodiment. Whereas, the contact resilience arm segments  8971  of the second signal interface  897  are not penetrated through the slots  8923  of the plastic tongue plate  892 , which is extended from and integrally formed with the plastic main body  891 . Of course, the first signal interface  896  is installed on the plastic main body  891  and the plastic tongue plate  892 . 
       FIG. 42  is a schematic side view illustrating an electrical receptacle according to a twenty-seventh embodiment of the present invention. Except for the following items, the other components and mechanisms of the electrical receptacle of this embodiment are similar to those of the twenty-sixth embodiment, and are not redundantly described herein. 
     The electrical receptacle  90  of this embodiment further comprises a third signal interface  908 . Moreover, the firsts signal interface  906  and the third signal interface  908  are both installed on the plastic main body  901  and the plastic tongue plate  902 . The extension segments  9072  of the second signal interface  907  are previously installed and fixed on the rear cover  905 . Moreover, the contact resilience arm segments  9071  of the second signal interface  907  are not penetrated through the slots  9023  of the plastic tongue plate  902 , which is extended from and integrally formed with the plastic main body  901 . 
       FIG. 43  is a schematic side view illustrating an electrical receptacle according to a twenty-eighth embodiment of the present invention. In this embodiment, a single plastic tongue plate is employed. As shown in  FIG. 43 , the electrical receptacle  91  comprises a first plastic main body  911  (also referred as a first insulating main body), an (insulating) plastic tongue plate  912 , a rear cover  915  (also referred as a second insulating main body), a first signal interface  916  (e.g. an eSATA signal interface), a second signal interface  917  (e.g. a USB 2.0 signal interface), and a third signal interface  918  (e.g. a USB 3.0 signal interface). The first plastic main body  911  has a first docking space  9191  and a second docking space  9192 . The plastic tongue plate  912  is fixed on a sidewall of a bottom part of the first plastic main body  911  and extended toward the front side. 
     In this embodiment, the extension segments  9162  of the eSATA signal interface  916  are previously installed and fixed on the rear cover  915 . Consequently, for assembling the electrical receptacle  81 , the rear cover  915  with the eSATA signal interface  916  is moved forwardly to be combined with the plastic main body  911 . 
     In accordance with the present invention, the electrical receptacle with a single tongue plate can support a single communication protocol (e.g. USB 2.0 or USB 3.0 communication protocol). 
       FIG. 44  is a schematic side view illustrating an electrical receptacle according to a twenty-ninth embodiment of the present invention. As shown in  FIG. 44 , the electrical receptacle  92  comprises a first plastic main body  921  (also referred as a first insulating main body), an (insulating) plastic tongue plate  922 , a rear cover  925  (also referred as a second insulating main body), a second signal interface  927  (e.g. a four-terminal USB 2.0 signal interface), and a third signal interface  928  (e.g. a five-terminal USB 3.0 signal interface). The first plastic main body  921  has a first docking space  9291  and a second docking space  9292 . The plastic tongue plate  922  is fixed on a sidewall of a bottom part of the first plastic main body  921  and extended toward the front side. 
     In this embodiment, the extension segments  9272  of the USB 2.0 signal interface  927  are previously installed and fixed on the rear cover  925 . Consequently, for assembling the electrical receptacle  91 , the rear cover  925  with the four-terminal USB 2.0 signal interface  927  is moved forwardly to be combined with the plastic main body  921  while the contact resilience arm segments  9271  are penetrated through the slots  9223  of the plastic tongue plate  922 . 
       FIG. 45  is a schematic side view illustrating an electrical receptacle according to a thirtieth embodiment of the present invention. Except for the following items, the other components and mechanisms of the electrical receptacle of this embodiment are similar to those of the twenty-ninth embodiment, and are not redundantly described herein. 
     In comparison with the twenty-ninth embodiment, the plastic main body  931 , the plastic tongue plate  932  and the third signal interface  938  (e.g. a USB 3.0 signal interface) of the electrical receptacle  93  of this embodiment are combined as a single structural body by a plastic insert molding process. Moreover, in this embodiment, the contact resilience arm segments  9371  of the second signal interface  937  are penetrated through the slots  9323  of the plastic tongue plate  932 , and the extension segments  9372  of the second signal interface  937  are installed and fixed on the rear cover  935 . 
       FIG. 46  is a schematic side view illustrating the electrical receptacle to be mounted on a motherboard according to a thirty-first embodiment of the present invention. Except for the following items, the other components and mechanisms of the electrical receptacle of this embodiment are similar to those of the twenty-ninth embodiment, and are not redundantly described herein. 
     In comparison with the twenty-ninth embodiment, the rear cover  945  of the electrical receptacle  94  of this embodiment is disposed over the plastic main body  941 . Moreover, the extension segments  9472  of the second signal interface  947  are installed on the rear cover  945 , and the contact resilience arm segments  9471  of the second signal interface  937  are extended downwardly from the extension segments  9472  and then penetrated through the slots  9423  of the tongue plate structure  942 . In addition, the pin segments  9473  of the second signal interface  947  are penetrated through the receiving holes  9411  of the plastic main body  941 . 
     In this embodiment, the third signal interface  948  is installed on the plastic main body  941  and the tongue plate structure  942 . 
     Moreover, a first end  94731  of the pin segment  9473  of the second signal interface  947  is connected to the extension segment  9472 , and a second end  94732  of the pin segment  9473  is inserted into the motherboard  940 . That is, the pin segments  9483  of the third signal interface  948  and the pin segments  9473  of the second signal interface  947  which are penetrated through the receiving holes  9411  of the plastic main body  941  are inserted into the insertion holes  9401  and  9402  of the motherboard  940 , respectively. 
     In this embodiment, the second signal interface  947  and the third signal interface  948  are respectively conductive terminal groups. The conductive terminals of each conductive terminal group are separated from each other and not electrically with each other. 
       FIG. 47  is a schematic side view illustrating the electrical receptacle according to a thirty-second embodiment of the present invention. Except for the following items, the other components and mechanisms of the electrical receptacle of this embodiment are similar to those of the thirty-first embodiment, and are not redundantly described herein. 
     In comparison with the thirty-first embodiment, the third signal interface  948  is not included in the electrical receptacle  95  of this embodiment. In this embodiment, the extension segments  9572  of the second signal interface  957  are previously installed and fixed on the rear cover  955 , and the contact resilience arm segments  9571  of the second signal interface  957  are penetrated through the slots  9523  of the plastic tongue plate  952 . 
     The following embodiments will be illustrated by referring to the electrical receptacle with a single tongue plate structure which is also the removable plastic tongue plate. 
       FIG. 48  is a schematic exploded view illustrating an electrical receptacle according to a thirty-third embodiment of the present invention.  FIG. 49  is a schematic exploded view illustrating the electrical receptacle of the thirty-third and taken along another viewpoint. Except for the following items, the other components and mechanisms of the electrical receptacle of this embodiment are similar to those of the twelfth embodiment, and are not redundantly described herein. 
     In comparison with the twelfth embodiment, the electrical receptacle  96  of this embodiment has no circuit board. Consequently, the tongue plate structure  963  is a removable plastic tongue plate, and the tongue plate structure  963  is integrally formed with the rear cover  965 . Moreover, the contact segments  9661  and the front ends of the extension segments  9662  of the first signal interface  966  and the third signal interface  968  are accommodated within the combination of the tongue plate structure  963  and the rear cover  965 . Moreover, in this embodiment, the extension segments  9672  of the second signal interface  967  are installed on a bottom part  9614  (e.g. a thin slab) of the plastic main body  961 , and the contact resilience arm segments  9671  of the second signal interface  967  are penetrated through the slots  9633  of the tongue plate structure  963 . 
       FIG. 50  is a schematic side view illustrating the electrical receptacle to be mounted on a motherboard according to a thirty-fourth embodiment of the present invention. Except for the following items, the other components and mechanisms of the electrical receptacle of this embodiment are similar to those of the thirty-third embodiment, and are not redundantly described herein. 
     In comparison with the thirty-third embodiment, the third signal interface  968  is not included in the electrical receptacle  97  of this embodiment. Moreover, in this embodiment, the extension segments  9772  of the second signal interface  977  (i.e. the USB 2.0 signal interface) are installed on the plastic main body  971 , and the contact resilience arm segments  9771  of the second signal interface  977  are penetrated through the slots  9733  of the single removable plastic tongue plate  973 . Moreover, the first signal interface  976  (i.e. the eSATA signal interface) is installed on the combination of the plastic tongue plate  973  and the rear cover  975 , and the pin segments  9763  of the first signal interface  976  are penetrated through the receiving holes  9711  of the plastic main body  971 . 
     Moreover, a first end  97631  of the pin segment  9763  of the first signal interface  976  is connected to the extension segment  9762 , and a second end  97632  of the pin segment  9763  is inserted into the motherboard  970 . The pin segments  9763  of the first signal interface  976  (i.e. the eSATA signal interface) and the pin segments  9773  of the second signal interface  977  (i.e. the USB 2.0 signal interface) are inserted into the insertion holes  9701  and  9702  of the motherboard  970 , respectively. 
     In this embodiment, the first signal interface  976  and the second signal interface  977  are respectively conductive terminal groups. The conductive terminals of each conductive terminal group are separated from each other and not electrically with each other. 
       FIG. 51  is a schematic exploded view illustrating an electrical receptacle according to a thirty-fifth embodiment of the present invention. Except for the following items, the other components and mechanisms of the electrical receptacle of this embodiment are similar to those of the twenty-fourth embodiment, and are not redundantly described herein. 
     In comparison with the twenty-fourth embodiment, the tongue plate structure  983  of the electrical receptacle  98  is not fixed on the bottom part of the plastic main body  981 . That is, the tongue plate structure  983  is an individual component (i.e. a single removable plastic tongue plate). The tongue plate structure  983  is used for accommodating the first signal interface  986  and the third signal interface  988 . 
     Moreover, in this embodiment, the extension segments  9872  of the second signal interface  987  are previously installed and fixed on the rear cover  985 , and the contact resilience arm segments  9871  of the second signal interface  987  are penetrated through the slots  9833  of the single removable plastic tongue plate  983 . 
       FIG. 52  is a schematic assembled view illustrating an electrical receptacle according to a thirty-sixth embodiment of the present invention.  FIG. 53  is a schematic front view illustrating the electrical receptacle of the thirty-sixth embodiment.  FIG. 54  is a schematic exploded view illustrating the electrical receptacle of the thirty-sixth embodiment.  FIG. 55  is a schematic exploded view illustrating the electrical receptacle of the thirty-sixth embodiment and taken along another viewpoint. 
     In this embodiment, the electrical receptacle  99  comprises a plastic main body  991 , a removable plastic tongue plate  993  combined with a rear cover  995 , a first signal interface  996 , a second signal interface  997 , and a metallic casing  990 . 
     Moreover, after the removable plastic tongue plate  993  with the rear cover  995  and the plastic main body  991  are combined together, a first docking space  9991  and a second docking space  9992  are defined by the removable plastic tongue plate  993  and the plastic main body  991 . 
     In this embodiment, the plastic main body  991  is an integral plastic main body. Moreover, two lateral walls  9913  are located at bilateral sides of the plastic main body  991  and extended toward the front side. A shared profile  99131  is located at the front peripheries of the two lateral walls  9913 . Moreover, no any fixed plastic tongue plate is installed on the plastic main body  991 , and the first signal interface  996  and the second signal interface  997  are not included in the plastic main body  991 . Due to the shared profile  99131 , an electrical plug (not shown) with the first signal interface or the second signal interface can be coupled with the electrical receptacle  99 . 
     Moreover, the first signal interface  996  and the second signal interface  997  are installed on the removable plastic tongue plate  993 . The removable plastic tongue plate  993  is integrally formed with the rear cover  995 . The rear cover  995  has a plurality of fixing recesses  9952 . The extension segments  9962  of the first signal interface  996  and/or the extension segments  9972  of the second signal interface  997  are previously accommodated and fixed within the fixing recesses  9952 . 
     Moreover, each of the first signal interface  996  and the second signal interface  997  comprises a plurality of signal interface units (also referred as terminals). The first signal interface  996  is accommodated within the second docking space  9992 . The extension segment  9962  of each signal interface unit of the first signal interface  996  is partially or completely fixed in a corresponding fixing recess  9952 . It is noted that the fixing recesses  9952  may be formed on the other side of the rear cover  995  for fixing the extension segments  9972  of the signal interface units of the second signal interface  9991  that are accommodated within the first docking space  9991 . 
     Moreover, in this embodiment, the first signal interface  996  and the second signal interface  997  are an e-SATA signal interface and a USB 2.0 signal interface. 
       FIG. 56  is a schematic front view illustrating the electrical receptacle according to a thirty-seventh embodiment of the present invention.  FIG. 57  is a schematic exploded view illustrating the electrical receptacle of the thirty-seventh embodiment.  FIG. 58  is a schematic exploded view illustrating the electrical receptacle of the thirty-seventh embodiment and taken along another viewpoint. 
     In this embodiment, the electrical receptacle  18  comprises a plastic main body  181 , a rear cover  185 , a removable plastic tongue plate  183 , a first signal interface  186 , a second signal interface  187 , and a metallic casing  180 . Like the thirty-sixth embodiment, after the removable plastic tongue plate  183  with the rear cover  185  and the plastic main body  181  are combined together, a first docking space  1891  and a second docking space  1892  are defined by the removable plastic tongue plate  183  and the plastic main body  181 . The first signal interface  186  is accommodated within the second docking space  1892 , which is arranged beside a surface of the removable plastic tongue plate  183 . The second signal interface  187  is accommodated within the first docking space  1891 , which is arranged beside another surface of the removable plastic tongue plate  183 . 
     In this embodiment, the plastic main body  181  is an integral plastic main body. Moreover, two lateral walls  1813  are located at bilateral sides of the plastic main body  181  and extended toward the front side. In comparison with the thirty-sixth embodiment, after the electrical receptacle  18  is assembled, a gap  18901  is created between the bottom part  1814  of the plastic main body  181  and the removable plastic tongue plate  183 . 
     In the following embodiments, the single tongue plate structure is applied to the signal interfaces other than the eSATA signal interface and the USB signal interface. It is to be noted that the following descriptions of preferred embodiments of this invention are presented herein for purpose of illustration and description only. 
       FIG. 59  is a schematic cross-sectional view illustrating the electrical receptacle according to a thirty-eighth embodiment of the present invention.  FIG. 60  is a schematic cross-sectional view illustrating the electrical receptacle according to a thirty-ninth embodiment of the present invention. As shown in  FIG. 59 , the electrical receptacle  28  is an electrical receptacle with a high definition multimedia interface (HDMI) signal interface  286 . As shown in  FIG. 60 , the electrical receptacle  29  is an electrical receptacle with a display port signal interface  296 . In these two embodiments, the tongue plate structures are installed on the plastic main body  281  and the plastic main body  291 . Moreover, the removable plastic tongue plates  283  and  293  may be integrally formed with the rear covers  285  and  295 , respectively. 
     Moreover, the HDMI signal interface  286  as shown in  FIG. 59  is installed on the combination of the removable plastic tongue plate  283  and the rear cover  285 . Similarly, the display port signal interface  296  as shown in  FIG. 60  is installed on the combination of the removable plastic tongue plate  293  and the rear cover  295 . 
       FIG. 61  is a schematic side view illustrating an electrical plug applied to the electrical receptacle of the present invention. The electrical plug  39  may comply with the above-mentioned communication protocols (e.g. the eSATA signal interface, the USB 2.0 signal interface and/or the USB 3.0 signal interface). The electrical plug  39  has a tongue plate receiving space  391  for accommodating various tongue plate structures that are described in the above embodiment. 
     From the above description, the electrical receptacle of the present invention can be easily assembled. In the electrical receptacle of the present invention, the signal interface structure segments are not excessively centralized to a single plastic main body, and thus the drawbacks encountered from the prior art will be eliminated. Especially for the high-speed signal interfaces, the distributed arrangement of the signal interface structure segments is effective to reduce the signal interference between adjacent signal interfaces. Consequently, the electrical receptacle of the present invention is industrially valuable. 
     While the invention has been described in terms of what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention needs not be limited to the disclosed embodiment. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims which are to be accorded with the broadest interpretation so as to encompass all such modifications and similar structures.