Terminal module

Abstract

The invention relates to a terminal module used for an electric connector, the terminal module comprises a plurality of terminals arranged in a row along the transverse direction, each terminal is provided with a contact part, the terminal module further comprises an insulating part, the insulating part fixedly holds the contact part, and the insulating part is arranged in the row. The upper shielding sheet is arranged on one side of the row of terminals, the lower shielding sheet is arranged on the other side of the row of terminals, and at least one of the upper shielding sheet and the lower shielding sheet is integrally provided with a plurality of grounding contact parts aligned with the plurality of contact parts of the row of terminals. And the conductive piece is electrically connected with the upper shielding sheet and the lower shielding sheet.

Description

[Technical field]

[0001] The invention relates to a terminal module for an electric connector, and in particular to a terminal module for transmitting high-frequency and high-speed signals. [Background technology]

[0002] With the development of the Internet and big data, the requirements for the speed of connector signal transmission are getting higher and higher. In order to meet the higher signal transmission requirements, the frequency of signal transmission is also gradually increasing. However, this faces the problem of high-frequency signal interference, which makes it difficult to improve signal transmission.

[0003] US Patent Application No. US20210328384A1 discloses a conductive grounding shield, which is a plurality of split shields or a one-piece shield. Please refer to the previous case Figure 3 As shown in FIG. 1 , a combined conductive ground shield and a metal ground terminal are also disclosed.

[0004] U.S. patent application No. US20220352675A1 discloses a terminal module having a corrugated plate, which can be arranged on the top surface, the bottom surface, or both the top surface and the bottom surface of the terminal module. The corrugated plate is electrically coupled to a grounding conductor and can be made of a conductive material or a lossy material. The electrically lossy material generally has a volume conductivity of about 1 to 100,000 Siemens / meter.

[0005] US Patent No. US11322869B2 discloses a terminal module for an electrical connector, the terminal module includes a terminal row, the terminal row includes a signal terminal and a ground terminal, each terminal includes a docking cantilever portion and a tail portion, a front fixing member for fixing the docking cantilever, a rear fixing member for fixing the tail portion, and a grounding bridge, the grounding bridge extends between each grounding terminal to ground the grounding terminals, the grounding bridge is formed integrally with the grounding terminal and includes a plate located in the middle portion. The plate of the grounding bridge extends across the middle portion of the signal terminal, that is, parallel to and spaced apart from the middle portion of the signal terminal, and is in close proximity to the signal terminal, for resonance control of the signal transmitted by the signal terminal.

[0006] US Patent No. US11469554B2 discloses a terminal module, which includes a conductive terminal, a housing for holding the conductive terminal, and a ground shield, the ground shield being separated from the middle portion of the conductive terminal by the housing. The ground shield can be stamped from a metal plate and can have a right-angle bend. The ground shield can be attached to the housing portion. The ground shield may include a body, a ground mating end extending from the body, and a ground mounting end extending from the body.

[0007] US patent application No. US20140127946A1 discloses a socket connector, which includes a housing, a first row of terminals, a second row of terminals, a plurality of first conductive members, and a plurality of second conductive members, wherein the conductive members are made of conductive resin and are used to electrically connect a plurality of ground terminals in the terminals. The conductive member has a base and a protrusion. When a long and thin metal plate is inserted, the conductive members can be connected to each other, that is, integrated together, and can be flexibly applied.

[0008] In the previous case, the grounding plate is only provided on one side of the grounding terminal or the grounding plate and the grounding terminal are provided separately, and the shielding and grounding effects are poor.

[0009] Therefore, an improved terminal module is needed to overcome the deficiencies of the prior art. [Summary of the invention]

[0010] The main purpose of the present invention is to provide a terminal module, which can improve the performance of high-frequency and high-speed signal transmission.

[0011] To achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a terminal module, which is used for an electrical connector, the terminal module includes a row of terminals arranged in a horizontal direction, the terminals are provided with contact portions, and further include an insulating member, the insulating member fixes the contact portions, an upper shielding sheet arranged on one side of the row of terminals and a lower shielding sheet arranged on the other side of the row of terminals and a plurality of conductive members, at least one of the upper shielding sheet and the lower shielding sheet is integrally provided with a plurality of grounding contact portions aligned with the plurality of contact portions of the row of terminals, and the conductive member electrically connects the upper shielding sheet and the lower shielding sheet.

[0012] Compared with the prior art, the advantages of the terminal module of the present invention are that at least one of the upper shielding plate and the lower shielding plate of the terminal module for the electrical connector of the present invention is integrally provided with multiple grounding contact portions aligned with the multiple contact portions of the row of terminals, and the conductive member electrically connects the upper shielding plate and the lower shielding plate, thereby having better high-frequency and high-speed performance.

Brief Description of the Drawings

[0013] Figure 1 It is a three-dimensional diagram of an electrical connector according to the present invention.

[0014] Figure 2 yes Figure 1 A rear view of the electrical connector is shown.

[0015] Figure 3 yes Figure 1 An exploded view of the electrical connector is shown.

[0016] Figure 4 yes Figure 3 An exploded view of the electrical connector from another perspective is shown.

[0017] Figure 5 yes Figure 3 A three-dimensional view of the upper terminal module of the electrical connector is shown.

[0018] Figure 6 yes Figure 5 A three-dimensional view of the upper terminal module from another perspective is shown.

[0019] Figure 7 yes Figure 5 A side view of the upper terminal module is shown.

[0020] Figure 8 is along Figure 5 Cross-sectional view along the AA direction.

[0021] Fig. 9 is along Figure 5 Cross-sectional view along the BB direction.

[0022] Fig.10 yes Figure 5 Exploded view of the upper terminal module shown.

[0023] Fig.11 yes Fig.10 An exploded view of the upper terminal module from another perspective is shown.

[0024] Fig.12 yes Fig.11 A three-dimensional view of the first submodule of the upper terminal module is shown.

[0025] Fig.13 yes Fig.11 An exploded view of the first submodule is shown.

[0026] Fig.14 yes Fig.13 A further exploded view of the first submodule is shown.

[0027] Fig.15 yes Fig.14 A further exploded view of another perspective of the first submodule is shown.

[0028] Fig.16 yes Fig.12 A perspective view of the conductive element of the first submodule is shown.

[0029] Fig.17 yes Fig.16 Exploded view of the conductive parts shown.

[0030] Fig.18 It is a side view of an upper terminal module according to a second embodiment of the electrical connector of the invention.

[0031] Fig.19 yes Fig.18An exploded view of the first submodule of the upper terminal module is shown.

[0032] Fig. 20 yes Fig.18 An exploded view of the second submodule of the upper terminal module is shown.

[0033] Fig.21 It is a three-dimensional view of a portion of an upper terminal module according to a third embodiment of the electrical connector of the invention.

[0034] Fig. 22 yes Fig.21 A side view of the upper terminal module is shown.

[0035] Fig.23 yes Fig.21 An exploded view of the first submodule of the upper terminal module is shown. [Specific implementation method]

[0036] like Figure 1-17 As shown, an electrical connector 100 in accordance with the present invention can be installed on an external circuit board (not shown) and can be matched with a docking connector (not shown). The electrical connector 100 includes an insulating body 10 and a terminal module 20 accommodated in the insulating body 10.

[0037] See also Figure 1-4 The insulating body 10 includes a main body 11 and a cover body 12 that can be matched with the main body 11. The main body 11 includes a pair of docking ports 110 that can be matched with a docking connector and are arranged at intervals in the up-down direction, and a through hole 111 arranged between the pair of docking ports 110. The cover body 12 includes a top cover 121 and a rear cover 122. The rear cover 122 is provided with a plurality of through slots 120.

[0038] See also Figure 3-12 , the terminal module 20 includes an upper terminal module 21, a lower terminal module (not shown), and a spacer 24 disposed between the upper terminal module 21 and the lower terminal module (not shown). The upper terminal module 21 includes a first submodule 210, a second submodule 220, and a pair of fixing plates 230 disposed on the side to fix the first submodule 210 and the second submodule 220 together. The front areas of the first submodule 210 and the second submodule 220 together form a mating area electrically connected to the two opposite surfaces of the docking connector. The spacer 24 is provided with a plurality of vents 240 that are connected to the through holes 111 on the main body 11 and pass through the spacer 24 from front to back. During assembly, the fixing plate 230 fixes the first submodule 210, the second submodule 220 and the cover body 12 together and then assembles them into the main body 11.

[0039] Specifically, the first submodule 210 includes a first row of terminals 201 arranged at intervals in the transverse direction, an insulating member 213 for holding the first row of terminals 201, an upper shielding sheet 2140 arranged on the upper side of the first row of terminals 201, a lower shielding sheet 2141 arranged on the lower side of the first row of terminals 201, and a conductive member 216 electrically connecting the upper shielding sheet 2140 and the lower shielding sheet 2141. The insulating member 213 is integrally formed with the first row of terminals 201. The first row of terminals 201 includes a signal pair terminal 2011 for transmitting differential signals and a bypass terminal 2012 for transmitting other signals such as low speed, power supply, control, etc. In the invention, the first row of terminals 201 includes four bypass terminals 2012, corresponding to other signal channels such as low speed, power supply, control, etc. Eight pairs of signal pair terminals 2011 correspond to eight high-speed signal channels. The eight pairs of signal pair terminals 2011 are evenly divided into two groups, which are respectively arranged on both sides of the bypass terminal 2012. According to specific needs, the number of high-speed signal channels can be any number greater than or equal to one, and the other signal channels such as low-speed, power supply, control, etc. can be increased or decreased, or even absent. Each terminal in the first row of terminals 201 includes a contact portion 211 that can be matched with a docking connector, a mounting portion 212 that is arranged opposite to the contact portion 211 and can be matched with the circuit board, and a connecting portion 215 located between the contact portion 211 and the mounting portion 212. The connecting portion 215 includes a horizontal portion 2151 connected to the contact portion 211, a vertical portion 2152 connected to the mounting portion 212, and an inclined portion 2153 connecting the horizontal portion 2151 and the vertical portion 2152.

[0040] The upper shielding sheet 2140 is arranged on one side of the row of terminals and is spaced apart from the row of terminals by a first distance, and the lower shielding sheet 2141 is arranged on the other side of the row of terminals and is spaced apart from the row of terminals by a second distance. The first distance is equal to the second distance. The upper shielding sheet 2140 and the lower shielding sheet 2141 surround the signal terminals of the row of terminals to form a stripline structure, which is similar to the structural design of a PCB, to achieve better high-speed transmission performance.

[0041] The upper shielding sheet 2140 and the lower shielding sheet 2141 are both sheet metal plates, and are bent according to the overall extension shape of the entire first submodule 210. The upper shielding sheet 2140 and the lower shielding sheet 2141 can be a single metal plate or a multi-piece metal plate arranged in the transverse direction. The upper shielding sheet 2140 and the lower shielding sheet 2141 are located on opposite sides of the first row of terminals 201, which can achieve better high-speed transmission performance. The width dimensions of the upper shielding sheet 2140 and the lower shielding sheet 2141 in the transverse direction are greater than or equal to the outermost dimensions of the first row of terminals 201 in the transverse direction, so that the entire first row of terminals 201 can be covered in the width direction, and have a better shielding function. The upper shielding sheet 2140 and the lower shielding sheet 2141 are not electrically connected to the first row of terminals 201. The upper shielding sheet 2140 and the lower shielding sheet 2141 are spaced apart from the first row of terminals by the insulating member 213, so that the first row of terminals 201 are exposed to the air except for the portions formed on the insulating member 213. The upper shielding sheet 2140 and the lower shielding sheet 2141 are provided with a plurality of through holes 2143 and covering portions 2144 located between adjacent through holes 2143, each of the covering portions 2144 is aligned with a corresponding signal pair terminal 2011, and the width of the covering portion 2144 in the lateral direction is greater than the width of the corresponding signal pair terminal 2011. Specifically, the through holes 2143 are elongated, so that air can flow between the through holes 2143 on the upper shielding sheet 2140, the space between the upper shielding sheet 2140 and the lower shielding sheet 2141, and the through holes 2143 on the lower shielding sheet 2141, so that an air heat dissipation channel can be formed. The through groove 120 on the cover body 12 is connected to the through hole 2143 on the upper shielding plate 2140, the space between the upper shielding plate 2140 and the lower shielding plate 2141, the through hole 2143 on the lower shielding plate 2141, the space between the first submodule 210 and the second submodule 220, the through hole 2143 on the second submodule 220 that is the same as the first submodule 210, the vent hole 240 of the spacer 24, and the through hole 111 on the main body 11 for air communication, so that the electrical connector 100 as a whole has an air heat dissipation channel.

[0042] See also Figure 13-15, the upper shielding sheet 2140 is provided with a plurality of grounding contact portions 2111 and a plurality of grounding mounting portions 2121. The plurality of grounding contact portions 2111 and the plurality of grounding mounting portions 2121 are integrally stamped from the corresponding shielding sheet. The grounding contact portions 2111 are aligned with the contact portions 211 of the first row of terminals 201 in the transverse direction, and the contact portion 211 of each of the signal pair terminals 2011 is located between an adjacent pair of the grounding contact portions 2111. Similarly, the plurality of grounding mounting portions 2121 are aligned with the mounting portions 212 of the first row of terminals 201 in the transverse direction, and the mounting portion 212 of each of the signal pair terminals 2011 is located between an adjacent pair of the grounding mounting portions 2121. It is understandable that the plurality of grounding contact portions 2111 and the plurality of grounding mounting portions 2121 can also be formed on the lower shielding sheet 2141. Alternatively, some of the plurality of grounding contact portions 2111 and the plurality of grounding mounting portions 2121 are formed on the upper shielding sheet 2140, and the remaining are formed on the lower shielding sheet 2141. In a similar manner, the upper shielding sheet and the lower shielding sheet of the second submodule 220 may include an integrally formed grounding contact portion and / or a grounding mounting portion. Further, the upper shielding sheet 2140 includes one or more elastic sheets 524 integrally punched out for contacting the lower shielding sheet 2141. The elastic sheet 524 may also be punched out from the lower shielding sheet 2141 and extend toward the upper shielding sheet 2140. The upper shielding sheet 2140 and the lower shielding sheet 2141 also include overhang features for impedance control, such as a front extension portion 526 located between every two grounding contact portions 2111.

[0043] See also Figure 14-15, the insulating member 213 is in the shape of a thin strip extending in the transverse direction. In this embodiment, the number of the insulating members 213 is four, which is one arranged on the horizontal part 2151, one on the vertical part 2152 and two on the inclined part 2153, and the two insulating members 213 arranged on the inclined part 2153 are connected together at both ends in the transverse direction. The insulating member 213 is provided with a plurality of mounting protrusions 2131, and the upper shielding sheet 2140 and the lower shielding sheet 2141 are both provided with mounting holes 2145 that cooperate with the mounting protrusions 2131. Both ends of each insulating member 213 in the transverse direction extend beyond the upper shielding sheet 2140 and the lower shielding sheet 2141, and a protrusion 2130 is formed at the exceeding part. The pair of fixing sheets 230 are provided with mounting through holes 2300 corresponding to the protrusions 2130, and the protrusions 2130 cooperate with the corresponding mounting through holes 2300 to fix the upper terminal module 21. Furthermore, the protrusion 2130 extends beyond the mounting through hole 2300, and the protruding portion is then hot-riveted to strengthen the stability of the connection between the fixing plate 230 and the insulating member 213. The number of insulating members 213 can be increased or decreased according to specific needs. The number of mounting protrusions 2131 can also be set on only one insulating member 213, or on each insulating member 213, as required.

[0044] The conductive member 216 may be made of metal or other conductive materials. The conductive member 216 may be manufactured separately and then assembled to the upper shielding sheet 2140 and the lower shielding sheet 2141. The conductive member 216 may also be an injection moldable conductive material directly molded to the upper shielding sheet 2140 and the lower shielding sheet 2141. The plastic conductive material may use a conductive plastic material with a surface resistance less than or equal to 0.1 ohm / square block, or a conductive plastic material with a volume resistivity less than or equal to 0.02 ohm-cm. Of course, according to specific needs, a conductive plastic material with a surface resistance greater than 0.1 ohm / square centimeter may also be used, or a conductive plastic material with a volume resistivity greater than 0.02 ohm-cm may be used. When direct molding of plastic materials is adopted, the conductive member 216 may be molded after the upper shielding sheet 2140, the lower shielding sheet 2141 and the insulating member 213 are assembled to electrically connect the upper shielding sheet 2140 and the lower shielding sheet 2141, or the conductive member 216 may be molded on the insulating member 213 first, and then the upper shielding sheet 2140 and the lower shielding sheet 2141 are assembled. Of course, when the conductive member 216 is assembled after being molded separately, the conductive member 216 may be assembled after the upper shielding sheet 2140, the lower shielding sheet 2141 and the insulating member 213 are assembled, or the conductive member 216 may be assembled with the insulating member 213 first, and then the upper shielding sheet 2140, the lower shielding sheet 2141 and the conductive member 216 are assembled to electrically connect.

[0045] In the present invention, the conductive member 216 is manufactured by separate molding and then assembled on the upper shielding sheet 2140, the lower shielding sheet 2141 and the insulating member 213. Specifically, the insulating member 213 is provided with a plurality of openings 2132, and the upper shielding sheet 2140 and the lower shielding sheet 2141 are provided with a plurality of through holes 2142 that penetrate through both sides thereof. The through holes 2142 of the upper shielding sheet 2140 and the lower shielding sheet 2141 are aligned with the corresponding openings 2132. During assembly, the upper shielding sheet 2140, the lower shielding sheet 2141 and the insulating member 213 are assembled first, and then the conductive member 216 is passed through the corresponding openings 2132 and the through holes 2142. The openings 2132 may be provided on each of the insulating members 213, or the openings 2132 may be provided on only some of the insulating members 213. Specifically, in the present invention, the opening 2132 is provided on the insulating member 213 located at the horizontal portion 2151 and the vertical portion 2152, so as to electrically connect the upper shielding sheet 2140 and the lower shielding sheet 2141 in the area close to the ground contact portion 2111 and the ground mounting portion 2121. The insulating member 213 is provided with the opening 2132 between each adjacent signal pair terminal 2011.

[0046] See also Figure 16-17 , the conductive member 216 is not connected into a whole in the lateral direction, but is discretely arranged one by one. Specifically, the conductive member 216 is composed of a plurality of separate conductive rivets, and each conductive member 216 includes a horizontal portion 2161 and a vertical portion 2162 connected to the horizontal portion 2161. The lateral dimension of the horizontal portion 2161 is greater than the lateral dimension of the vertical portion 2162. The dimension of the vertical portion 2162 in the vertical direction is greater than the dimension of the horizontal portion 2161 in the vertical direction. The dimension of the horizontal portion 2161 is greater than the dimension of the through hole on the upper shielding sheet 2140, and the horizontal portion 2161 is located outside the upper shielding sheet 2140 and stops at the upper shielding sheet 2140. The vertical portion 2162 passes through the corresponding through holes of the upper shielding sheet 2140 and the lower shielding sheet 2141 and the opening 2132 of the insulating member 213. Further, the vertical portion 2162 is hot-riveted after extending beyond the lower shielding sheet 2141, so as to strengthen the connection between the conductive member 216 and the upper shielding sheet 2140 and the lower shielding sheet 2141. Further, each of the discrete conductive members 216 is embedded with a metal member 217, and the metal member 217 penetrates the horizontal portion 2161 and extends to the vertical portion 2162 to enhance the strength of the conductive member 216. The metal member 217 is integrally formed with the conductive member 216. The metal member 217 is formed by stamping a metal flat plate material. Before the conductive member 216 is assembled to the upper shielding sheet 2140 and the lower shielding sheet 2141, the metal members 217 in each conductive member 216 are connected together by a material strip, and the material strip is removed after the assembly is completed. The metal member 217 does not have direct mechanical contact with the upper shielding sheet 2140 and the lower shielding sheet 2141.

[0047] The structure of the second submodule 220 is similar to that of the first submodule 210 , with the main difference being that the size is relatively shorter and the direction in which the contact portion 211 protrudes is opposite to that of the first submodule. The other structures are almost the same as those of the first submodule 210 , and thus will not be described in detail here.

[0048] The overall length of the lower terminal module is much smaller than that of the upper terminal module 21, so that it can adopt a traditional structure to achieve the same effect as the upper terminal module 21. Of course, it can also adopt a structure similar to the upper terminal module 21 in the present invention. Therefore, the specific structure of the lower terminal module will not be repeated.

[0049] like Figure 18-20As shown, it is a second embodiment of the upper terminal module 21' in accordance with the present invention. Compared with the first embodiment, in this embodiment, the grounding contact portion 2111' of the first submodule 210' is arranged on one of the upper shielding sheet 2140' and the lower shielding sheet 2141', and the grounding mounting portion 2121' is arranged on the other. Specifically, in this embodiment, the grounding contact portion 2111' is arranged on the upper shielding sheet 2140', and the grounding mounting portion 2121' is arranged on the lower shielding sheet 2141'. Of course, the grounding mounting portion 2121' can also be arranged on the upper shielding sheet 2140', and the grounding contact portion 2111' can be arranged on the lower shielding sheet 2141', or both the upper shielding sheet 2140' and the lower shielding sheet 2141' are provided with the grounding contact portion 2111' and the grounding mounting portion 2121'.

[0050] The ground contact portion 2111' of the second submodule 220' is arranged on the lower shielding sheet 2141', and the ground mounting portion 2121' is arranged on the upper shielding sheet 2140'. Of course, the arrangement may be the same as that of the first submodule 210', or the upper shielding sheet 2140' and the lower shielding sheet 2141' may both be provided with the ground contact portion 2111' and the ground mounting portion 2121'.

[0051] like Figure 21-23 , which is a partial view of a third embodiment of an upper terminal module 21" in accordance with the present invention. Compared with the first embodiment, in this embodiment, the conductive members 216" of the first submodule 210" and the second submodule 220" are integrally formed with the corresponding upper shielding sheet 2140", the lower shielding sheet 2141" and the insulating member 213".

Claims

1. A terminal module for an electrical connector, the terminal module comprising a row of terminals arranged in a transverse direction, the terminals being provided with contact portions, characterized in that: It further includes an insulating member that holds the contact portion, an upper shielding sheet arranged on one side of the row of terminals, a lower shielding sheet arranged on the other side of the row of terminals, and a plurality of conductive members, at least one of the upper shielding sheet and the lower shielding sheet being integrally provided with a plurality of grounding contact portions aligned with the plurality of contact portions of the row of terminals, and the conductive member electrically connects the upper shielding sheet and the lower shielding sheet.

2. The terminal module according to claim 1, characterized in that: The row of terminals is provided with a plurality of mounting portions, the insulating member fixes the plurality of mounting portions, and at least one of the upper shielding sheet and the lower shielding sheet is integrally provided with a plurality of grounding mounting portions aligned with the plurality of mounting portions of the row of terminals.

3. The terminal module according to claim 2, characterized in that: All of the ground contact portions are disposed on one of the upper shielding sheet or the lower shielding sheet, and all of the ground mounting portions are disposed on the other of the upper shielding sheet or the lower shielding sheet.

4. The terminal module according to claim 2, characterized in that: The plurality of ground contact portions and the plurality of ground mounting portions are both disposed on the upper shielding sheet.

5. The terminal module according to claim 2, wherein: The plurality of ground contact portions and the plurality of ground mounting portions are both disposed on the lower shielding sheet.

6. The terminal module according to claim 2, characterized in that: Some of the plurality of ground contact portions and the plurality of ground mounting portions are disposed on the upper shielding sheet, and the other ones are disposed on the lower shielding sheet.

7. The terminal module according to claim 2, wherein: The upper shielding sheet is spaced apart from the row of terminals by a first distance, and the lower shielding sheet is spaced apart from the row of terminals by a second distance, wherein the first distance is equal to the second distance.

8. The terminal module according to claim 2, wherein: The insulating member is provided with a plurality of openings, and the upper shielding sheet and the lower shielding sheet are provided with through holes aligned with the openings, and each conductive member includes a horizontal portion and a vertical portion connected to the horizontal portion, and the vertical portion passes through the corresponding through holes of the upper shielding sheet and the lower shielding sheet and the openings of the insulating member.

9. The terminal module according to claim 8, characterized in that: Each of the conductive parts is embedded with a metal part, and the metal part passes through the horizontal part and extends to the vertical part. The free end of the vertical part extends through the lower shielding sheet and is fixed to the lower shielding sheet by hot melting.

10. The terminal module according to claim 2, wherein: The row of terminals includes a plurality of pairs of signal terminals for transmitting differential signals. The upper shielding sheet and the lower shielding sheet are both provided with a plurality of through holes for air circulation, and covering portions located between adjacent through holes. Each of the covering portions is aligned with a pair of corresponding signal terminals, and a width of the covering portion in a lateral direction is greater than a width of a pair of signal terminals.

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