Three-phase silicon controlled trigger

Abstract

The utility model relates to the technical field of silicon controlled rectifiers, in particular to a three-phase silicon controlled rectifier trigger, which comprises a trigger body, the surface of a fixing block and the inner wall of a fixing frame are respectively provided with a convenient dismounting mechanism, and the surface of the trigger body is respectively provided with a wiring anti-winding mechanism. The surface of the trigger body is provided with a heat conduction and heat dissipation mechanism. According to the utility model, the trigger is more practical and convenient to operate during installation, wiring processing can be carried out on a wire body when the trigger is used, and the phenomenon of short circuit of the trigger body caused by accumulation and winding of the wire body in the use process of the trigger is avoided; and heat generated in the trigger body can be quickly dissipated when the trigger is used, so that the phenomenon that the normal use of the trigger body is influenced by over-high internal temperature of the trigger body in the use process of the trigger is avoided, and the service life of the trigger is longer when the trigger is used.

Description

Technical Field

[0001] The utility model relates to the technical field of thyristors, in particular to a three-phase thyristor trigger. Background Art

[0002] Thyristor rectifier is a very important power device that can be used to control high voltage and large current. Currently, the rated current of thyristor devices can range from a few mA to more than 5,000 A, and the rated voltage can exceed 10,000 V. Thyristor trigger is a supporting product of SCR. The principle is similar and it is mainly used for AC and DC voltage adjustment.

[0003] The existing thyristor phase-shift trigger also has problems such as poor heat dissipation effect, inconvenient installation and lack of protection function. In addition, the existing thyristor phase-shift trigger has some disadvantages to a certain extent. The thyristor phase-shift trigger needs to be assembled before use. The assembly steps of the existing thyristor phase-shift trigger are often cumbersome and inconvenient during assembly, which makes the trigger not practical and inconvenient to operate during installation; the thyristor phase-shift trigger needs to be wired to prevent entanglement when in use. The existing thyristor phase-shift trigger is prone to entanglement and accumulation between the wires when in use, which makes it impossible to wire the wires when the trigger is in use, which easily leads to wire accumulation and entanglement during use of the trigger, causing a short circuit in the trigger body; the surface temperature of the thyristor phase-shift trigger will continue to rise during use. The existing thyristor phase-shift trigger is not efficient in heat conduction and heat dissipation during use, which makes it impossible to quickly dissipate the heat generated inside the trigger body when the trigger is in use, which easily leads to the internal temperature of the trigger body being too high during use, affecting the normal use of the trigger body, shortening the service life of the trigger when in use. Utility Model Content

[0004] The purpose of the present invention is to provide a three-phase thyristor trigger to solve the problems in the above-mentioned background technology that the assembly steps of the thyristor are often complicated, the assembly is not convenient, the wire body cannot be wired, and the heat conduction and heat dissipation efficiency is not high enough.

[0005] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a three-phase thyristor trigger, comprising a trigger body, the surface of the trigger body is installed with a power supply terminal, the surface of the power supply terminal is plugged with a wire body, the surface of the trigger body is installed with a thyristor, the surfaces of both sides of the trigger body are installed with a fixed block, both sides of the trigger body are provided with a fixing frame, the fixed block and the inner wall of the fixing frame slide with each other, the surface of the fixed block and the inner wall of the fixing frame are provided with a convenient disassembly and assembly mechanism, the interior of the convenient disassembly and assembly mechanism includes a guide slider, a guide slot and a convenient disassembly and assembly part, the surface of the trigger body is provided with a wiring anti-winding mechanism, the interior of the wiring anti-winding mechanism includes a wiring hole, a wiring board and a wiring anti-winding group, the surface of the trigger body is provided with a heat conduction and heat dissipation mechanism, the interior of the heat conduction and heat dissipation mechanism includes a heat conduction plate, a heat dissipation through-hole, heat dissipation fins and mounting screws.

[0006] Preferably, the convenient disassembly and assembly portion is arranged on the surface of the fixed block and the inner wall of the fixed frame, the convenient disassembly and assembly portion is composed of an extension spring, an arc-shaped clip and a groove, a guide slider is installed on the surface of the fixed block, and a guide groove is provided on the inner wall of the fixed frame, the guide groove and the surface of the guide slider slide with each other, and the surface of the guide slider is provided with a groove.

[0007] Preferably, an arc-shaped clip is provided inside the groove, the arc-shaped clip and the inner wall of the groove are slidably matched with each other, the arc-shaped clip and the inner wall of the fixing frame are snap-fitted with each other, and an extension spring is installed inside the groove, and one end of the extension spring is fixed to the surface of the arc-shaped clip.

[0008] Preferably, the wiring anti-entanglement group is arranged on the surface of the trigger body, and the wiring anti-entanglement group is composed of a wiring tube, a telescopic spring, an arc-shaped splint and a telescopic column. The surface of the trigger body is installed with a wiring board by screws, and the interior of the wiring board is provided with wiring holes at equal intervals.

[0009] Preferably, the surface of the wiring board is installed with equally spaced wiring tubes, the wiring tubes are connected to the inside of the wiring holes, the inside of the wiring tubes is provided with arc-shaped clamping plates for clamping the wires, and the inner walls of the wiring tubes are installed with equally spaced telescopic springs.

[0010] Preferably, one end of the telescopic spring is fixed to the surface of the arc-shaped clamping plate, and the inner wall of the wiring tube is installed with equally spaced telescopic columns, and one end of the telescopic column is fixed to the surface of the arc-shaped clamping plate.

[0011] Preferably, a heat conducting plate for heat conduction is installed inside the trigger body, and the inner wall of the trigger body is provided with heat dissipation holes at equal intervals, and the heat dissipation holes are connected to the interior of the trigger body.

[0012] Preferably, the surface of the trigger body is provided with equidistant heat dissipation fins, the surface of the heat dissipation fins is threadedly connected with mounting screws, and one end of the mounting screw passes through the heat dissipation fins and is threadedly fastened to the surface of the trigger body.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: the three-phase thyristor trigger not only enables the trigger body to be installed at a specified position of the fixing frame as needed when the trigger is in use, making the trigger more practical and convenient to operate during installation, but also enables the wires to be routed when the trigger is in use, thereby avoiding the phenomenon of wire accumulation and entanglement during use of the trigger, which may cause a short circuit in the trigger body, but also enables the heat generated inside the trigger body to be quickly dissipated when the trigger is in use, thereby avoiding the phenomenon of the internal temperature of the trigger body being too high during use, which may affect the normal use of the trigger body, thereby extending the service life of the trigger when in use;

[0014] 1. By providing a convenient disassembly and assembly mechanism, the user places the trigger body between the fixing frames, so that the trigger body drives the fixing block to move. At this time, the fixing block drives the guide slider to slide inside the guide slot. Under the joint action of the guide slider and the guide slot, the trigger body and the fixing block are guided. At this time, the arc-shaped clip is driven to move under the elastic force of the extension spring inside the groove, so that the arc-shaped clip is clamped to the inner wall of the corresponding fixing frame. Under the action of the arc-shaped clip, the trigger body is prevented from displacement, so that the trigger body is installed at the specified position of the fixing frame, realizing the convenient assembly function of the trigger, so that when the trigger is used, the trigger body can be installed at the specified position of the fixing frame as needed, making the trigger more practical and convenient to operate during installation;

[0015] 2. By providing a wiring anti-entanglement mechanism, the user installs the wiring board on the surface of the trigger body with screws, and the user pulls the wires on the surface of the power strip respectively, so that one end of the wire passes through the wiring hole and extends to the inside of the wiring barrel. At this time, the arc-shaped clamping plate is driven to move under the joint action of the telescopic spring and the telescopic column inside the wiring barrel, so that the arc-shaped clamping plate moves to contact the surface of the wire. Under the action of the arc-shaped clamping plate, the wire is clamped inside the wiring barrel and the wiring hole, avoiding the accumulation of the wire on the surface of the trigger body, causing safety hazards such as short circuit of the trigger body, and realizing the function of the trigger to prevent the wire from being entangled, so that the wire can be wired when the trigger is in use, avoiding the phenomenon of wire accumulation and entanglement during use of the trigger, which may cause a short circuit in the trigger body.

[0016] 3. By providing a heat conduction and heat dissipation mechanism, the user places the heat dissipation fins on the surface of the trigger body respectively, and the user tightens the mounting screws, and the heat dissipation fins are respectively installed on the surface of the trigger body under the action of the mounting screws, and the interior of the trigger body is heat-conducted under the action of the heat conduction plate, and the interior of the trigger body is dissipated under the action of the heat dissipation fins, so that the heat is discharged from the interior of the trigger body through the heat dissipation through-holes, and the interior of the trigger body is quickly dissipated, thereby realizing the heat conduction and heat dissipation function of the trigger, so that the heat generated inside the trigger body can be quickly dissipated when the trigger is in use, avoiding the phenomenon that the internal temperature of the trigger body is too high during the use of the trigger and affecting the normal use of the trigger body, and extending the service life of the trigger when in use. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the three-dimensional structure of the utility model;

[0018] Figure 2 This is a schematic diagram of the main cross-sectional structure of the utility model;

[0019] Figure 3 It is a schematic diagram of an enlarged side cross-section structure of the utility model;

[0020] Figure 4 For the utility model Figure 2 An enlarged structural diagram of the convenient disassembly and assembly mechanism;

[0021] Figure 5 For the utility model Figure 2 An enlarged structural diagram of the wiring anti-entanglement mechanism;

[0022] Figure 6 For the utility model Figure 3 Schematic diagram of the enlarged structure of the heat conduction and heat dissipation mechanism.

[0023] In the figure: 1. Trigger body; 101. Power supply terminal; 102. Thyristor; 103. Fixing frame; 104. Fixing block; 2. Convenient disassembly and assembly mechanism; 201. Guide slider; 202. Guide slide; 203. Convenient disassembly and assembly part; 2031. Extension spring; 2032. Arc-shaped clamp; 2033. Groove; 3. Wiring anti-winding mechanism; 301. Wiring hole; 302. Wiring board; 303. Wiring anti-winding group; 3031. Wiring barrel; 3032. Extension spring; 3033. Arc-shaped splint; 3034. Extension column; 4. Heat conduction and heat dissipation mechanism; 401. Heat conduction plate; 402. Heat dissipation through hole; 403. Heat dissipation fin; 404. Mounting screws. DETAILED DESCRIPTION

[0024] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. In addition, the terms "first", "second", "third", "upper, lower, left, right", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. At the same time, in the description of the present invention, unless otherwise clearly stipulated and limited, the terms "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0025] The utility model provides a three-phase thyristor trigger with a structure as follows Figure 1 and Figure 2 As shown, it includes a trigger body 1, the surface of the trigger body 1 is installed with a power supply bar 101, the surface of the power supply bar 101 is plugged with a wire body, the surface of the trigger body 1 is installed with a thyristor 102, the surfaces of both sides of the trigger body 1 are installed with a fixing block 104, and both sides of the trigger body 1 are provided with a fixing frame 103, and the fixing block 104 and the inner wall of the fixing frame 103 slide together.

[0026] Furthermore, if Figure 2 and Figure 3 As shown, the surface of the fixed block 104 and the inner wall of the fixed frame 103 are both provided with a convenient disassembly and assembly mechanism 2, the interior of the convenient disassembly and assembly mechanism 2 includes a guide slider 201, a guide slot 202 and a convenient disassembly and assembly portion 203, the convenient disassembly and assembly portion 203 is provided on the surface of the fixed block 104 and the inner wall of the fixed frame 103, the convenient disassembly and assembly portion 203 is composed of an extension spring 2031, an arc-shaped clamp 2032 and a groove 2033, the surface of the fixed block 104 is provided with a guide slider 201, the inner wall of the fixed frame 103 is provided with a guide slot Toward the slide groove 202, the guide slide groove 202 and the surface of the guide slider 201 slide with each other, the surface of the guide slider 201 is provided with a groove 2033, the interior of the groove 2033 is provided with an arc-shaped clamp 2032, the arc-shaped clamp 2032 and the inner wall of the groove 2033 slide with each other, the arc-shaped clamp 2032 and the inner wall of the fixed frame 103 are clamped with each other, and the interior of the groove 2033 is installed with an extension spring 2031, and one end of the extension spring 2031 is fixed to the surface of the arc-shaped clamp 2032.

[0027] During implementation, the trigger body 1 drives the fixed block 104 to move. At this time, the fixed block 104 drives the guide slider 201 to slide inside the guide slot 202. Under the joint action of the guide slider 201 and the guide slot 202, the trigger body 1 and the fixed block 104 are guided. At this time, the arc-shaped clip 2032 is driven to move under the elastic force of the extension spring 2031 inside the groove 2033, so that the arc-shaped clip 2032 is stuck to the inner wall of the corresponding fixing frame 103. Under the action of the arc-shaped clip 2032, the trigger body 1 is prevented from displacement, so that the trigger body 1 is installed at the specified position of the fixing frame 103, so as to realize the function of convenient assembly of the trigger.

[0028] Furthermore, if Figure 2 and Figure 4 As shown, the surface of the trigger body 1 is provided with a wiring anti-winding mechanism 3, the interior of the wiring anti-winding mechanism 3 includes a wiring hole 301, a wiring plate 302 and a wiring anti-winding group 303, the wiring anti-winding group 303 is provided on the surface of the trigger body 1, the wiring anti-winding group 303 is composed of a wiring tube 3031, a telescopic spring 3032, an arc-shaped clamping plate 3033 and a telescopic column 3034, the surface of the trigger body 1 is installed with a wiring plate 302 by screws, the interior of the wiring plate 302 is provided with wiring holes 301 at equal intervals, the wiring The surface of the plate 302 is installed with equally spaced wiring tubes 3031, which are connected to the interior of the wiring hole 301. The interior of the wiring tube 3031 is provided with an arc-shaped clamping plate 3033 for clamping the wire body. The inner wall of the wiring tube 3031 is installed with equally spaced telescopic springs 3032, one end of the telescopic spring 3032 is fixed to the surface of the arc-shaped clamping plate 3033, and the inner wall of the wiring tube 3031 is installed with equally spaced telescopic columns 3034, one end of the telescopic column 3034 is fixed to the surface of the arc-shaped clamping plate 3033.

[0029] During implementation, the user installs the wiring board 302 on the surface of the trigger body 1 with screws, and the user pulls the wires on the surface of the power strip 101 respectively, so that one end of the wire passes through the wiring hole 301 and extends to the inside of the wiring barrel 3031. At this time, the arc-shaped clamping plate 3033 is driven to move under the joint action of the telescopic spring 3032 and the telescopic column 3034 inside the wiring barrel 3031, so that the arc-shaped clamping plate 3033 moves to contact the surface of the wire. Under the action of the arc-shaped clamping plate 3033, the wire is clamped inside the wiring barrel 3031 and the wiring hole 301, avoiding the wire accumulation on the surface of the trigger body 1, causing safety hazards such as short circuit in the trigger body 1, so as to realize the function of the trigger to prevent the wire wiring from being entangled.

[0030] Furthermore, if Figure 3 and Figure 6As shown, the surface of the trigger body 1 is provided with a heat-conducting and heat-dissipating mechanism 4, and the interior of the heat-conducting and heat-dissipating mechanism 4 includes a heat-conducting plate 401, heat-dissipating through-holes 402, heat-dissipating fins 403 and mounting screws 404. The interior of the trigger body 1 is provided with a heat-conducting plate 401 for heat conduction, and the inner wall of the trigger body 1 is provided with heat-dissipating through-holes 402 at equal intervals. The heat-dissipating through-holes 402 are connected to the interior of the trigger body 1. The surface of the trigger body 1 is provided with heat-dissipating fins 403 at equal intervals, and the surface of the heat-dissipating fins 403 is threadedly connected with mounting screws 404, and one end of the mounting screw 404 passes through the heat-dissipating fin 403 and is threadedly fastened to the surface of the trigger body 1.

[0031] During implementation, when the trigger body 1 works for a long time, the internal temperature will be too high. The user places the heat dissipating fins 403 on the surface of the trigger body 1 respectively, tightens the mounting screws 404, and installs the heat dissipating fins 403 on the surface of the trigger body 1 respectively under the action of the mounting screws 404. The interior of the trigger body 1 is heat-conducted under the action of the heat conducting plate 401, and the interior of the trigger body 1 is dissipated under the action of the heat dissipating fins 403, so that the heat is discharged from the interior of the trigger body 1 through the heat dissipating through-holes 402, and the interior of the trigger body 1 is quickly dissipated to realize the heat conduction and heat dissipation function of the trigger.

[0032] Working principle: When in use, first place the trigger body 1 at the specified position, and the user places the trigger body 1 between the fixing frame 103, so that the trigger body 1 drives the fixing block 104 to move. At this time, the fixing block 104 drives the guide slider 201 to slide inside the guide slot 202, and the trigger body 1 and the fixing block 104 are guided by the joint action of the guide slider 201 and the guide slot 202. At this time, the arc-shaped clip 2032 is driven to move under the elastic force of the extension spring 2031 inside the groove 2033, so that the arc-shaped clip 2032 is stuck to the inner wall of the corresponding fixing frame 103. Under the action of the arc-shaped clip 2032, the trigger body 1 is prevented from displacement, thereby installing the trigger body 1 at the specified position of the fixing frame 103 to realize the function of convenient assembly of the trigger, so that the trigger body 1 can be installed at the specified position of the fixing frame 103 as needed when the trigger is used, making the trigger more practical and convenient to operate during installation.

[0033] Afterwards, the user installs the wiring board 302 on the surface of the trigger body 1 with screws, and the user pulls the wires on the surface of the power strip 101 respectively, so that one end of the wire passes through the wiring hole 301 and extends to the inside of the wiring barrel 3031. At this time, the arc-shaped clamping plate 3033 is driven to move by the joint action of the telescopic spring 3032 and the telescopic column 3034 inside the wiring barrel 3031, so that the arc-shaped clamping plate 3033 moves to contact the surface of the wire. Under the action of the arc-shaped clamping plate 3033, the wire is clamped inside the wiring barrel 3031 and the wiring hole 301 to prevent the wire from accumulating on the surface of the trigger body 1, causing safety hazards such as short circuit in the trigger body 1, so as to realize the anti-entanglement function of the trigger for wire wiring, so that the wire can be wired when the trigger is used, avoiding the phenomenon of wire accumulation and entanglement during use of the trigger, which may cause a short circuit in the trigger body 1.

[0034] Subsequently, when the trigger body 1 works for a long time, the internal temperature will be too high. The user places the heat dissipation fins 403 on the surface of the trigger body 1 respectively, tightens the mounting screws 404, and installs the heat dissipation fins 403 on the surface of the trigger body 1 respectively under the action of the mounting screws 404. The interior of the trigger body 1 is heat-conducted under the action of the heat conduction plate 401, and the interior of the trigger body 1 is dissipated under the action of the heat dissipation fins 403, so that the heat is discharged from the interior of the trigger body 1 through the heat dissipation through-holes 402. The interior of the trigger body 1 is quickly dissipated to realize the heat conduction and heat dissipation function of the trigger, so that the heat generated inside the trigger body 1 can be quickly dissipated when the trigger is in use, thereby avoiding the phenomenon that the internal temperature of the trigger body 1 is too high during the use of the trigger and affecting the normal use of the trigger body 1, making the trigger have a longer service life when in use, and finally completing the use of the thyristor.

[0035] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the present invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be encompassed within the present invention. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

Claims

1. A three-phase thyristor trigger, comprising a trigger body (1), characterized in that: The surfaces of the trigger body (1) are all installed with power supply terminals (101), the surfaces of the power supply terminals (101) are all plugged with wires, the surfaces of the trigger body (1) are all installed with thyristors (102), the surfaces of both sides of the trigger body (1) are all installed with fixing blocks (104), both sides of the trigger body (1) are provided with fixing frames (103), the fixing blocks (104) and the inner walls of the fixing frames (103) are slidably matched with each other, the surfaces of the fixing blocks (104) and the inner walls of the fixing frames (103) are both provided with convenient disassembly and assembly mechanisms (2), the convenient disassembly and assembly mechanisms (2) are provided with fixing blocks (104) and the inner walls of the fixing frames (103). The interior of the assembly mechanism (2) includes a guide slider (201), a guide slot (202) and a convenient disassembly portion (203); the surface of the trigger body (1) is provided with a wiring anti-winding mechanism (3); the interior of the wiring anti-winding mechanism (3) includes a wiring hole (301), a wiring board (302) and a wiring anti-winding group (303); the surface of the trigger body (1) is provided with a heat conduction and heat dissipation mechanism (4); the interior of the heat conduction and heat dissipation mechanism (4) includes a heat conduction plate (401), a heat dissipation through hole (402), a heat dissipation fin (403) and an installation screw (404).

2. A three-phase thyristor trigger according to claim 1, characterized in that: The convenient disassembly and assembly portion (203) is arranged on the surface of the fixed block (104) and the inner wall of the fixed frame (103); the convenient disassembly and assembly portion (203) is composed of an extension spring (2031), an arc-shaped clamp (2032) and a groove (2033); a guide slider (201) is installed on the surface of the fixed block (104); a guide slot (202) is provided on the inner wall of the fixed frame (103); the guide slot (202) and the surface of the guide slider (201) are slidably matched with each other; and the surface of the guide slider (201) is provided with a groove (2033).

3. A three-phase thyristor trigger according to claim 2, characterized in that: An arc-shaped clamp (2032) is provided inside the groove (2033), and the arc-shaped clamp (2032) and the inner wall of the groove (2033) are slidably matched with each other. The arc-shaped clamp (2032) and the inner wall of the fixing frame (103) are engaged with each other. An extension spring (2031) is installed inside the groove (2033), and one end of the extension spring (2031) is fixed to the surface of the arc-shaped clamp (2032).

4. A three-phase thyristor trigger according to claim 1, characterized in that: The wiring anti-entanglement group (303) is arranged on the surface of the trigger body (1), and the wiring anti-entanglement group (303) is composed of a wiring tube (3031), a telescopic spring (3032), an arc-shaped clamping plate (3033) and a telescopic column (3034). The surface of the trigger body (1) is mounted with a wiring board (302) by screws, and the interior of the wiring board (302) is provided with wiring holes (301) at equal intervals.

5. A three-phase thyristor trigger according to claim 4, characterized in that: The surface of the wiring board (302) is equipped with wiring tubes (3031) at equal intervals. The wiring tubes (3031) are connected to the interior of the wiring hole (301). The interior of the wiring tubes (3031) is equipped with arc-shaped clamping plates (3033) for clamping the wires. The inner wall of the wiring tubes (3031) is equipped with telescopic springs (3032) at equal intervals.

6. A three-phase thyristor trigger according to claim 5, characterized in that: One end of the telescopic spring (3032) is fixed to the surface of the arc-shaped clamping plate (3033), and the inner wall of the wiring tube (3031) is installed with equally spaced telescopic columns (3034), and one end of the telescopic columns (3034) is fixed to the surface of the arc-shaped clamping plate (3033).

7. The three-phase thyristor trigger according to claim 1, characterized in that: The interior of the trigger body (1) is provided with a heat conducting plate (401) for heat conduction, and the inner wall of the trigger body (1) is provided with heat dissipation holes (402) at equal intervals, and the heat dissipation holes (402) are connected to the interior of the trigger body (1).

8. The three-phase thyristor trigger according to claim 1, characterized in that: The surface of the trigger body (1) is provided with equidistant heat dissipation fins (403), and the surface of the heat dissipation fins (403) is threadedly connected with mounting screws (404), and one end of the mounting screw (404) passes through the heat dissipation fins (403) and is threadedly fastened to the surface of the trigger body (1).

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