Electrical connector including shielding net connected to conductive body

The application provides an electrical connector, which includes: an insulating body, including a first surface and a second surface opposite to the first surface; a plurality of grounding terminals and a plurality of signal terminals, the plurality of grounding terminals and the plurality of signal terminals being connected to the insulating body in an array; a conductive body, connected to the insulating body from the first surface; and a conductive shielding net. The shielding net is connected to the insulating body from the second surface and electrically connected to the conductive body, and the plurality of grounding terminals are electrically connected with the shielding net through the conductive body. According to the electrical connector of the application, by the shielding net, shielding in an insertion direction may be implemented better, thereby preventing or reducing crosstalk generated during a signal transmission of the electrical connector.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Chinese Patent Application No. 201920815386X, filed on May 31, 2019, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

The application relates to an electrical connector, and more particularly to an electrical connector for signal transmission, which may prevent or reduce crosstalk generated during a signal transmission of the electrical connector.

BACKGROUND

In an electronic or communication system, circuits and electronic modules are usually arranged on some separated printed circuit boards, and these separated printed circuit boards are connected to each other by electrical connectors. An electrical connector implements connection of a backplane and each daughterboard. Along with constantly increase of bandwidth requirements from users, more and more circuits have been arranged in a specified narrow region of each printed circuit board and work at increasing frequencies. Correspondingly, an electrical connector between printed circuit boards transmits data at an increasing rate, and a signal transmission rate has reached 6 Gbps and even 10 Gbps or higher. Such a high-speed and high-density connection requires a high requirement on a signal integrity (SI) performance index, particularly a numerical value of a crosstalk index, of the electrical connector.

In order to preventing such crosstalk, efforts have been made to a certain extent in prior arts. For example, an electrical connector is provided in Patent Application No. CN205863449U, the electrical connector includes a conductive plastic for connecting grounding terminals, and a plurality of linearly arranged rectangular blocks are arranged between adjacent terminal rows to form shields between two differential signal terminal pairs adjacent to the rectangular blocks. However, since the conductive plastic is formed integrally with a U-shaped plastic body by a secondary injection molding manner, and due to differences between material characteristics, a preparation process is complex and unfavorable for mass production. In a preparation and forming process of the conductive plastic, extension of the linear rectangular block in a length direction may not be excessively increased for enhancement of a shielding effect under the limit of spaces of a mold and the U-shaped plastic body, and this is because excessive extension of the rectangular block in the length direction may cause a corresponding rectangular groove in the corresponding U-shaped plastic body excessively long, thereby reduce structural stability of the U-shaped plastic body.

In addition, an electrical connector is provided in No. CN202930673U, the electrical connector includes a double-layer shielding structure for shielding a signal terminal in an insertion direction. However, the metal shielding structure is directly connected with a grounding terminal by a spring finger, and such direct physical connection between metal components may cause metal debris, thereby bringing negative interference influence to the whole mechanism.

In view of this, the application discloses an electrical connector, to overcome the shortcomings.

SUMMARY

The application is intended to provide an electrical connector, which may prevent or reduce crosstalk generated during a signal transmission of the electrical connector.

The application provides an electrical connector, which includes: an insulating body, comprising a first surface and a second surface opposite to the first surface; a plurality of grounding terminals and a plurality of signal terminals connected to the insulating body in an array respectively; a conductive body, connected to the insulating body from the first surface; and a shielding net. The shielding net is connected to the insulating body from the second surface and electrically connected to the conductive body, and the plurality of grounding terminals are electrically connected with the shielding net through the conductive body. By the shielding net, the electrical connector may be shielded from a insertion direction, thereby preventing or reducing crosstalk generated during a signal transmission of the electrical connector.

Further, at least one row of the plurality of grounding terminals in a row direction is electrically connected with the shielding net through the conductive body. Further, at least one column of the plurality of grounding terminals in a column direction is electrically connected with the shielding net through the conductive body. Therefore, the grounding terminals are common ground together in the row and/or column directions for grounding the shielding net better, thereby ensure a shielding effect.

Further, the shielding net comprises a plurality of terminal opening rows, each terminal opening row comprises a plurality of grounding terminal openings for the grounding terminals of the electrical connector to pass through and a plurality of signal terminal openings for the signal terminals to pass through, the signal terminal openings are configured to space the signal terminals from the shielding net, and in any terminal opening row, the grounding terminal openings and signal terminal openings are alternately arranged and spaced from one another in the row direction. The shielding net distinguishes different openings, thereby effectively enlarging a shielding area.

Further, at least one grounding terminal opening in any terminal opening row and the corresponding grounding terminal opening in another adjacent terminal opening row are staggered in the column direction, and projections of at least one signal terminal opening in any terminal opening row and the corresponding signal terminal opening in another adjacent terminal opening row in the column direction are at least partially overlapped. By such staggered arrangement, the signal terminals may be isolated better and be arranged more close for increasing the density, thereby performance of the electrical connector may be improved.

Further, one or more connecting tabs formed by downward bending are arranged at two ends of the shielding net in an extension direction of the terminal opening row respectively. By the connecting tabs, the shielding net may be firmly fixed to the insulating body of the electrical connector.

Further, a plurality of L-shaped protrusions are arranged on the conductive body. A short edge portion of the L-shaped protrusion extends along the column direction of the array and is electrically connected to the corresponding grounding terminal, a long edge portion of the L-shaped protrusion extends along the row direction of the array, and the shielding net directly contacts with a top of the L-shaped protrusion in an insertion direction. Further, the L-shaped protrusions are arranged in notches of the insulating body respectively, and a row of the L-shaped protrusions are formed between every two adjacent terminal rows. Thus, the differential terminal pairs may be shielded well to avoid crosstalk interference by the arrangement of the L-shaped protrusions. Meanwhile, the shielding net is electrical connected with the grounding terminals through the L-shaped protrusions, thereby the differential signal terminal pairs be shielded well in six directions.

Further, a protruding portion is formed on the second surface of the insulating body for fitting with the shielding net.

Further, the shielding net comprises a plurality of signal terminal openings for the signal terminals to pass through, each of the signal terminal openings fits with the protruding portion.

Further, the shielding net is arranged on the second surface of the insulating body and forms a substantially flat surface with the protruding portion.

Further, the insulating body comprises a plurality of first terminal openings for the grounding terminals to pass through and a plurality of second terminal openings for the signal terminals to pass through. The protruding portion is formed at a portion surrounding the second terminal opening. After mounting, the shielding net is arranged on the second surface of the insulating body, and the shielding net is ensured to be electrically connected with the L-shaped protrusions well, and meanwhile, forms a relatively flat surface structure with the protruding portions on the second surface.

Further, every two adjacent signal terminals in the row direction of the array form a differential signal terminal pair, and each differential signal terminal pair passes through the corresponding signal terminal opening and is at a distance from the signal terminal opening. By the distance between the signal terminal opening and the differential signal terminal pair, the short-circuit may be effectively prevented.

Further, the shielding net is a metal shielding net.

Further, the shielding net is a conductive plastic shielding net.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The technical solutions in the embodiments of the application will be described below in combination with the drawings in the embodiments of the application in detail. It is to be noted that the embodiments in the application and characteristics thereof may be combined without conflicts.

As shown inFIG. 1toFIG. 4, an electrical connector1according to a first embodiment of the application generally includes an insulating body11, a conductive body12, a plurality of grounding terminals13and a plurality of signal terminals. The conductive body12is located relative to the insulating body11, wherein the conductive body12is an individual component that is integrally formed and assembled and matched with the insulating body11. Convenience for a preparation in manufacture, easiness for mass production and high replaceability are ensured. The plurality of grounding terminals13and the plurality of signal terminals are connected to the insulating body11in an array. Every two adjacent signal terminals in a row direction X of the array form a differential signal terminal pair14, and the differential signal terminal pairs14(including a first signal terminal14aand a second signal terminal14b) and the grounding terminals13are alternately arranged in the row direction X to form terminal rows. In an unlimited example shown inFIG. 1, the array includes six terminal rows and nine terminal columns, each terminal row includes three differential signal terminal pairs14, and three grounding terminals13are alternately arranged between the differential terminal pairs14. Moreover, projections of the differential signal terminal pairs14in adjacent terminal rows in a column direction Y perpendicular to the row direction X are at least partially overlapped. But the present disclosure does not limited thereto, in other embodiment, two differential signal terminal pairs14may arranged two grounding terminals13therebetween.

As shown inFIG. 2a, a plurality of L-shaped protrusions121are arranged on the conductive body12, the L-shaped protrusions121are arranged in notches11aof the insulating body11(as shown inFIG. 7) respectively, and every two adjacent terminal rows formed a row of the L-shaped protrusions therebetween. The L-shaped protrusion121includes a short edge portion121aand a long edge portion121b, a first end of the short edge portion121ais connected with a first end of the long edge portion121b, the short edge portion121apreferably forms a right-angle connection with the long edge portion121b, the short edge portion121aextends along the column direction Y and is electrically connected to the corresponding grounding terminal13by a second end of the short edge portion121a, and the long edge portion121bextends along the row direction X to isolate a part of the differential signal terminal pairs14in adjacent terminal rows that are at least partially overlapped in the column direction Y. Preferably, one signal terminal of the differential signal terminal pair14is isolated.

By such a specific arrangement for the L-shaped protrusions121of the electrical connector, the long edge portion121bextending along the row direction X is intended to isolate the part of the differential signal terminal pairs14in the adjacent terminal rows that are at least partially overlapped in the column direction Y, there are enough distances between the notches11ain the insulating body11in the row direction X, thereby strength and structural stability of the insulating body11may be ensured. In addition, the L-shaped protrusions121of the conductive body12may also shield adjacent differential signal terminal pairs14in the column direction Y to avoid crosstalk interference.

As shown inFIG. 2a, the differential signal terminal pairs14in adjacent terminal rows are staggered so that the first signal terminal14ain the differential signal terminal pair14in one terminal row and a grounding terminal13in the adjacent terminal row are arranged relative to each other, and the second signal terminal14bin the differential signal terminal pair14in the terminal row and the first signal terminal14ain the differential signal terminal pair14in the adjacent terminal row are arranged relative to each other, thereby the relatively arranged terminals along the column direction Y form signal terminal columns. That is, as shown inFIG. 2a, if the leftmost signal terminal column is a first signal terminal column and the rightmost signal terminal column is a ninth signal terminal column, the first signal terminals14aand the grounding terminals are alternately arranged along the column direction Y in the first signal terminal column, and the second signal terminals14band the first signal terminals14aare alternately arranged along the column direction Y in a second signal terminal column.

The terminals in adjacent terminal rows are staggered, so that crosstalk interference generated during a high-frequency signal transmission may further be reduced or avoided, adaptation to a chip and a circuit board may be implemented better, and slots or openings in the insulating body may be scattered as much as possible to reduce structural weak links so that an overall structure of the electrical connector becomes more stable.

As shown inFIG. 2a, the long edge portions121bof the L-shaped protrusions121may respectively extend through a region between the adjacent signal terminals in the signal terminal columns along the row direction X. That is, the long edge portions121bof the L-shaped protrusions121are configured to respectively extend to a region between the second signal terminals14band first signal terminals14ain the signal terminal columns where the second signal terminals14band the first signal terminals14aare alternately arranged along the column direction Y.

By such arrangement, in the row direction X, adjacent differential signal terminal pairs14in the terminal rows are spaced and shielded by the grounding terminals13; and in the column direction Y, one side of the first signal terminal14ain each differential signal terminal pair14is shielded by the grounding terminal13, while the other side is shielded by the grounding terminal13and the L-shaped protrusion121, and both sides of the second signal terminals14bin the differential signal terminal pair14are shielded by the long edge portions121bof the L-shaped protrusions121. As such, any two adjacent signal terminal pairs14may be shielded, thereby the crosstalk generated during a signal transmission of the electrical connector may be prevented or reduced.

Preferably, a second end of the long edge portion121bof the L-shaped protrusion121may extend to a position flushed with the signal terminal in the corresponding signal terminal column in the column direction Y. That is, as shown inFIG. 2a, the long edge portion121bof the L-shaped protrusion121may extend in the region between the second signal terminal14b(on one side) and the first signal terminal14a(on the other side) of the same signal terminal column. An edge of the long edge portion is flushed with edges of the second signal terminal14band the first signal terminal14aalong the column direction Y (namely flushed with an imaginary flush line extending along the column direction Y).

By such a “flush” arrangement for the long edge portions121bof the L-shaped protrusions121, the differential signal terminal pairs14may be shielded well, meanwhile the notch11aof the insulating body11for arranging the L-shaped protrusion121therein is not too large, for ensuring structural strength of the insulating body11.

FromFIG. 2a, it can also be seen that, in the embodiment, the long edge portion121bof the L-shaped protrusion121may equidistant from two adjacent terminal rows respectively. As such, the long edge portion121bof the L-shaped protrusion121is arranged at a middle position between the adjacent terminal rows, so that the conductive body12and the insulating body11are structurally arranged more uniformly and stably. In addition, an extension height of the L-shaped protrusion121in an insertion direction Z perpendicular to both the row direction X and the column direction Y may be configured to be consistent with a depth of the notch11a. Therefore, the shielding of the signal terminal pairs14by the L-shaped protrusions121in the insulating body11may be ensured, and influence on connection and shielding between each of the grounding terminals13and signal terminal pairs14on the electrical connector and other connected components may be eliminated.

As shown inFIG. 2a, extension directions of the long edge portions121bof two adjacent rows of the L-shaped protrusions121relative to the short edge portions121aare opposite. InFIG. 2a, the long edge portions121bof the bottom row of the L-shaped protrusions121each extend leftwards relative to the short edge portions121a, and the long edge portions121bof the L-shaped protrusions in the adjacent row above each extend rightwards relative to the short edge portions121a.

The short edge portions121aof two adjacent L-shaped protrusions121in the column direction Y may extend along the same direction, and the long edge portions121bof two adjacent L-shaped protrusions121in the column direction Y may extend along the opposite direction.

The short edge portions121aof two adjacent L-shaped protrusions121in the row direction X may extend along the same direction, and the long edge portions121bof two adjacent L-shaped protrusions121in the row direction X may extend along the same direction.

By such an arrangement, a good shielding effect may be achieved, and the structural strength of the insulating body11may favorably be ensured.

FIG. 2billustrates another arrangement for the L-shaped protrusions121. The difference between the L-shaped protrusions121shown inFIG. 2aand that shown inFIG. 2bis that the short edge portions121aof two adjacent L-shaped protrusions121in the row direction X extend along the opposite direction and the long edge portions121bof two adjacent L-shaped protrusions121in the row direction X extend along the opposite direction. By such an arrangement, a good shielding effect may also be achieved.

As shown inFIG. 2aandFIG. 3, conductive protruding blocks122extending upwards are arranged on two opposite edges of the conductive body12in the column direction Y respectively, and an extension distance of the conductive protruding block122in the row direction X is equal to a distance from the first end to second end of the long edge portion121bof the L-shaped protrusion121, so that the differential signal terminal pairs14in the corresponding rows are shielded to avoid interference with other circuit structure/chip on the circuit board. Meanwhile, the conductive protruding blocks122may also provide a constructive interference when the conductive body12is connected with the insulating body11(for example, the conductive protruding blocks122on the conductive body12may form interference fit with the corresponding matched notches in the insulating body11) to reduce or avoid the risk of separation of the conductive body12from the insulating body11.

As shown inFIG. 7,FIG. 8aandFIG. 8b, a protruding rib113may be formed on the notch11a, and the protruding rib113forms interference fit with the L-shaped protrusion121(for conveniently showing the protruding rib113, the L-shaped protrusion121is not shown inFIG. 7,FIG. 8aandFIG. 8b), so that connection stability of the conductive body12and the insulating body11is enhanced. Such interference fit may be hard interference, that is, at least one protruding rib113is formed on an inner surface of the notch11a, and a corresponding lateral surface of the corresponding L-shaped protrusion121is flat, and when the L-shaped protrusion121is inserted into the notch11a, the L-shaped protrusion121is firmly clamped into the notch11aby the protruding rib113.

As shown inFIG. 8aandFIG. 8b, the protruding rib113on the notch11alinearly extends along the insertion direction Z, and a thickness of at least part of the protruding rib113may gradually decrease from top to bottom along the insertion direction Z to form a guide section, so that, when the conductive body12is inserted into the insulating body11from below shown inFIG. 8a, a part of the protruding rib with a relatively small thickness at the lower portion may conveniently guide the insertion of the L-shaped protrusion121and provide a gradually enhanced clamping effect along with increase of an insertion depth thereof. However, the disclosure is not limited thereto. In an alternative solution, a fit manner for the L-shaped protrusion121and the notch11amay be concave-convex fit or other equivalent means to achieve the effect of fixing the two.

As shown inFIG. 7, the insulating body11includes a plurality of first terminal openings111and a plurality of second terminal openings112, the plurality of grounding terminals13pass through the plurality of first terminal openings111respectively, and the plurality of signal terminals (including the first signal terminals14aand the second signal terminals14b) pass through the plurality of second terminal openings112respectively, wherein the first terminal openings111are communicated with the notches11arespectively, so that when the L-shaped protrusions121are inserted into the notches11a, the short edge portions121aof the L-shaped protrusions121may be electrically connected with the grounding terminals13.

As shown inFIG. 5andFIG. 6, the conductive body12includes a plurality of third terminal openings123and a plurality of fourth terminal openings124, the plurality of grounding terminals13pass through the plurality of third terminal openings123respectively and are electrically connected with the conductive body12, and the plurality of differential signal terminal pairs14pass through the plurality of fourth terminal openings124respectively and are disengaged from the conductive body12, wherein the fourth terminal opening124is a rectangular structure, a length D of a short edge of the rectangular structure is not less than 1.6 mm and a length L of a long edge adjacent to the short edge is not less than 2.7 mm.

FIG. 9illustrates an electrical connector according to a second embodiment of the disclosure. An arrangement thereof is substantially same as the arrangement for the first electrical connector shown inFIG. 1toFIG. 8b, one difference therebetween is the electrical connector according to the second embodiment including ten terminal rows and twelve terminal columns and the assembling manner for the conductive body is also different.

As shown inFIG. 10, the conductive body of the electrical connector in each embodiment of the disclosure may be of a split structure, for example, may adopt a two-piece structure shown inFIG. 10, which consists of two half portions electrically connected together. For an electrical connector with a large size due to relatively large numbers of grounding terminals and signal terminals, such two-piece structure (split structure) is convenient to manufacture.

As shown inFIG. 11andFIG. 12, in an electrical connector according to the application (including the first embodiment and the second embodiment), the insulating body11includes a first surface114and a second surface115opposite to the first surface114; the plurality of grounding terminals13and the plurality of signal terminals are connected to the insulating body11in an array; and the conductive body12is connected to the insulating body11from the first surface114. The electrical connector further includes a shielding net16, the shielding net16is made from a conductive material, and the conductive material may be a metal, conductive plastic . . . etc. The shielding net16is connected to the insulating body11from the second surface115and electrically connected to the conductive body12, and the plurality of grounding terminals13are electrically connected with the shielding net16through the conductive body12, so that shielding in a insertion direction Z may be implemented better by the shielding net16, and meanwhile, common ground of the grounding terminals13may also be ensured. In another embodiment (not shown) of the application, the shielding net may also be formed by injection molding together with the insulating body to be directly embedded into the second surface of the insulating body.

The conductive body12and the shielding net16may be made from a wave absorbing material, an electrically lossy material or the like, and the electrically lossy material is formed by adding a filler including a conductive particle into a binder. Examples of the conductive particle capable of forming the electrically lossy material as the filler may include a carbon or graphite in a fiber or sheet form, or other particle form. Metal in powder, sheet, fiber or other particle form may also be used for providing a proper electrical loss characteristic. Optionally, a combination of fillers may be used. For example, a metal-plated carbon particle may be used. Silver and nickel are proper plated metals for fibers. A coated particle may be used independently or combined with a filler of another fiber such as a carbon sheet for use.

In some embodiments, a binder may be a thermoplastic material and a high-temperature-resistant nylon material, and is for example routinely used for manufacturing the electrical connector to die-cast the electrically lossy material into an expected shape and position as part of manufacturing of the electrical connector. However, binder materials in many optional forms may be used. A curable material such as an epoxy resin may also be used as the binder. Optionally, a material such as a thermoplastic resin or adhesive may be used. Moreover, although the above-described binder material forms the binder surrounding the conductive particle filler to create the electrically lossy material, the application is not limited thereto. For example, according to another solution for the conductive body and the shielding net, the thermoplastic material or high-temperature-resistant nylon material routinely for manufacturing the electrical connector may also be injection-molded at first and then metal-plated with a conductive material such as copper, nickel, gold and silver, so that the formed conductive body and shielding net may be electrically connected with each other.

During specific implementation, the shielding net16may be arranged such that at least one row of the plurality of grounding terminals13in a row direction X is electrically connected with the shielding net16through the conductive body12, and/or such that at least one column of the plurality of grounding terminals13in a column direction Y is electrically connected with the shielding net16through the conductive body12. Therefore, the shielding net16ensure a perfect shielding effect.

As shown inFIG. 11toFIG. 13, the shielding net16is substantially a rectangular sheet structure, and includes a plurality of terminal opening rows, each terminal opening row includes a plurality of grounding terminal openings161for the grounding terminals of the electrical connector to pass through and a plurality of signal terminal openings162for the signal terminal pairs of the electrical connector to pass through, the signal terminal opening162is configured to space the signal terminal from the shielding net16, and in any terminal opening row, the grounding terminal openings161and signal terminal openings162are alternately arranged and separated from each other in the row direction X. Compared with a conventional shielding net, the shielding net16of the application distinguishes different openings and keeps a structural completeness and strength of the shielding net16, so that a shielding area is effectively enlarged.

In addition, fromFIGS. 11 and 12, it can also be seen that at least one grounding terminal opening161in any terminal opening row of the shielding net16and the corresponding grounding terminal opening161in another adjacent terminal opening row are staggered in the column direction Y, and projections of at least one signal terminal opening162in any terminal opening row and the corresponding signal terminal opening162in another adjacent terminal opening row in the column direction Y are at least partially overlapped. By such staggered arrangement, the signal terminals may be isolated better and be arranged more close for increasing the density, thereby performance of the electrical connector may be improved.

One or more connecting tabs163formed by downward bending may be arranged at two ends of the shielding net16in an extension direction of the terminal opening row respectively, the connecting tabs163are used for firmly fixing the shielding net16into the second surface115of the insulating body11, and the connecting tabs163may be formed integrally with the shielding net16.

As shown inFIG. 12, a plurality of L-shaped protrusions121are arranged on the conductive body12, wherein a short edge portion121aof the L-shaped protrusion121extends along the column direction Y of the array and is electrically connected to the corresponding grounding terminal13, a long edge portion121bof the L-shaped protrusion121extends along the row direction X of the array, and the shielding net16directly contacts with a top of the L-shaped protrusion121in an insertion direction Z. The L-shaped protrusions121are arranged in notches11aof the insulating body11, and a row of L-shaped protrusions121are formed between every two adjacent terminal rows. By such an arrangement, shielding in insertion direction is provided by the shielding net16and the conductive body12, shielding in four lateral directions is provided by the grounding terminals13and the L-shaped protrusions121, so that the effect of complete shielding in six space directions can be achieved.

Besides contacting with the L-shaped protrusions121of the conductive body12, the shielding net16may further fit with the grounding terminals13in a manner of setting sizes of the grounding terminal openings161or by additional spring arms (not shown) or the like, to directly connect with the grounding terminals13through the grounding terminal openings161.

As shown inFIG. 12andFIG. 13, on the second surface115of the insulating body11, a protruding portion116is formed at a portion surrounding the second terminal opening112. Moreover, when the shielding net16is connected to the second surface115, the shielding net16is electrically connected with the L-shaped protrusions121, and the second terminal openings162of the shielding net16fit with the protruding portions116. Preferably, after mounting, the shielding net16is arranged on the second surface115of the insulating body11and forms a relatively flat surface structure together with the protruding portions116on the second surface115. Further, the shielding net16and the protruding portions116are arranged substantially on the common plane.

In addition, a distance between each differential signal terminal pair14and the second terminal opening162may be ensured since the arrangement of the protruding portions116when each differential signal terminal pair14passes through the corresponding one signal terminal opening162in the shielding net16, and by the distance, the signal terminal pair14may be prevented from contacting with the shielding net16, thereby effectively preventing short-circuit and potential crosstalk influence.

The above is only the preferred embodiment of the application and not intended to limit the application. For those skilled in the art, the application may have various modifications and variations. Any modifications, equivalent replacements, improvements and the like made within the spirit and principle of the application shall fall within the scope of protection of the application.