CN114258373A

CN114258373A - Prevent and remove unmanned aerial vehicle

Info

Publication number: CN114258373A
Application number: CN202080057801.5A
Authority: CN
Inventors: 金应琪
Original assignee: Individual
Current assignee: Individual
Priority date: 2019-08-05
Filing date: 2020-08-04
Publication date: 2022-03-29
Also published as: KR20210016768A; WO2021025417A1; KR102307265B1

Abstract

The present invention relates to an unmanned aerial vehicle, and more particularly, to an unmanned aerial vehicle in which a propeller is easily replaced, and which can contain a fluid such as a chemical in the interior of the main body of the unmanned aerial vehicle without an additional storage tank and can spray in multiple directions with only one cartridge, in addition to an arm, a slide, and a main frame which are components of the unmanned aerial vehicle. The invention comprises the following steps: a body storing a fluid therein; a propeller unit provided in the main body so as to be capable of taking off; an injection unit provided at the main body to spray liquid to the outside; and a control unit provided in the main body to selectively control driving of the propeller unit or the injection unit.

Description

Prevent and remove unmanned aerial vehicle

Technical Field

The invention relates to a unmanned control plane, which is easy to replace propellers, adopts only one cartridge case except an arm lever, a slide way and a main frame, is internally provided with propellers, batteries, sensors and the like, and can spray in a plurality of directions.

Background

A general Unmanned Aerial Vehicle (Drone) is variously called depending on the situation, purpose, and country, and is generally a generic name of an Unmanned Aerial Vehicle (UAV) that can be controlled by radio waves, an aircraft that does not carry a person but realizes flight control by radio wave guidance, or a helicopter-shaped Unmanned Aerial Vehicle.

In this type of unmanned aerial vehicle, the unmanned aerial vehicle has an advantage in that it can maintain an appropriate height in a wide farmland and uniformly spray an appropriate amount of chemicals.

The unmanned aerial vehicle uses a detachable cartridge, and adopts a mode of downwards spraying a medicament, and adopts a complex combined structure that the lower part is provided with a leg structure equivalent to a Foot (Foot), and the upper part is provided with a propeller structure for flying, and the like.

However, in a forest farm having fruit trees such as an orchard, since it is difficult to fly effectively due to the fact that the structure of the unmanned aerial vehicle is hooked by the branches of the fruit trees or the bottom of the orchard, there is a problem that the prevention and control function cannot be effectively exerted, and there is a need for an unmanned aerial vehicle that is simpler in structure and more convenient to move.

Taking fruit trees as an example, in most cases, the interior of the tree is fruited, and the downward-spraying structure is difficult to directly spray the medicament to the fruit, so that an unmanned aerial vehicle capable of spraying upwards is needed.

Disclosure of Invention

(technical problem to be solved)

The present invention has been made to solve the above problems, and an object of the present invention is to provide an unmanned aerial vehicle in which a cartridge containing a fluid such as a chemical is used as a housing of a structure in which a propeller unit or a control unit is fitted, thereby minimizing members exposed to the outside of the unmanned aerial vehicle, minimizing collision with obstacles of the unmanned aerial vehicle generated when the unmanned aerial vehicle is controlled, and maximizing a control function.

(means for solving the problems)

As means for solving the above-described problems, in an embodiment of the present invention, as shown in fig. 1, there is provided an unmanned aerial vehicle including: a body 110 storing fluid therein; a propeller unit 120 mounted to a circular hole 112 formed in a structure penetrating the body 110 in an embedded structure; an injection unit 130 provided inside the main body 110 and having a nozzle portion 131 that injects a fluid contained inside the main body 110; and a control unit 140 disposed inside the body 110 in an embedded structure, controlling driving of the propeller unit 120 and the injection unit 130.

(Effect of the invention)

According to the embodiment of the invention, the cartridge containing the fluid such as the medicament is used as the shell (main body) of the structure embedded in the propeller unit or the control unit, thereby reducing the components exposed outside the unmanned aerial vehicle to the maximum extent, minimizing the collision between the unmanned aerial vehicle and the obstacle of the unmanned aerial vehicle when the unmanned aerial vehicle is controlled, and realizing the maximization of the control function.

And, set up the injection unit with embedded structure in the inside of unmanned aerial vehicle main part, can change the direction of shower nozzle at will, can realize the injection from a plurality of directions such as the lower part of fruit tree to upper portion, can ensure the efficiency of spraying the medicament.

Furthermore, the agent spraying mode of the spraying unit adopts an air static pressure spraying mode of sucking fluid by the pressure of air and spraying the fluid in a mist shape, so that the spraying in various directions including the lower part to the upper part of the fruit tree is realized, and the agent spraying range can be expanded.

And, set up the screw unit in the medicament section of thick bamboo inside with embedded structure can combine and be installed inside the circular port with the motor, adopt the mode of dismantling, can improve the efficiency of changing and maintaining.

Drawings

Fig. 1 is a plan view of a drone according to one embodiment of the present invention.

Fig. 2 is a cross-sectional view of the unmanned control plane with the propeller unit shown in fig. 1 as a reference.

Fig. 3 is a perspective view of the propeller unit shown in fig. 1.

Fig. 4 is a diagram illustrating an operation state of the propeller unit of fig. 1.

Fig. 5 is a cross-sectional view of the unmanned control plane with the spraying unit shown in fig. 1 as a reference.

Fig. 6 and 7 are sectional views of the nozzle portion of fig. 5, showing a rotation state of the head.

Fig. 8 is a sectional view a-a of fig. 6 and 7.

Fig. 9 is a bottom view of the drone controlling shown in fig. 1.

Fig. 10 is a perspective view of a protector combined with the circular hole of fig. 1.

Fig. 11 is a front view, a bottom view of the protector shown in fig. 10.

Fig. 12 is a view showing a state in which the protector of fig. 11 is coupled with a circular hole.

Description of the symbols

100: the unmanned control plane 110: main body

120: the propeller unit 130: injection unit

140: control unit

Detailed Description

In order to describe the present invention in sufficient detail to enable those skilled in the art to easily implement the technical idea of the present invention, the following description will be made with reference to the most preferred embodiments of the present invention.

When reference numerals are given to components in each drawing, the same reference numerals are used as much as possible even when the same components are shown in different drawings. Also, in explaining the present invention, if it is determined that a detailed description of related known structures or functions may obscure the gist of the present invention, the detailed description will be omitted.

A unmanned control plane according to an embodiment of the present invention is described in detail below with reference to fig. 1 to 12.

Fig. 1 is a plan view of a drone according to an embodiment of the present invention, fig. 2 is a sectional view of the drone with reference to a propeller unit shown in fig. 1, and fig. 3 is a perspective view of the propeller unit shown in fig. 1.

Referring to fig. 1 to 3, a unmanned control plane according to an embodiment of the present invention includes: a body 110 containing a fluid therein; a propeller unit 120 mounted to a circular hole 112 formed in a structure penetrating the body 110 in an embedded structure; an injection unit 130 provided inside the main body 110 and having a nozzle portion 131 that injects a fluid contained inside the main body 110; and a control unit 140 disposed inside the body 110 in an embedded structure, controlling driving of the propeller unit 120 and the injection unit 130.

The body 110 has an accommodating space, the inside of which is empty, and fluid can be stored in the accommodating space. In this case, the concept of the fluid includes liquid such as water, a medicament, a pesticide, and the like. The shape of the main body 110 does not adopt a structure of the unmanned aerial vehicle in which a frame structure of the unmanned aerial vehicle and a drug cartridge are separately formed in the existing unmanned aerial vehicle, but changes the structure of the drug cartridge itself containing the drug, so that the main body can be used as the drug cartridge to contain the drug, and simultaneously, basic structures such as an external arm lever, a slide way, a main frame and the like can be removed, and main components such as a propeller unit or a control unit can be contained. This kind of structure is inside at the cartridge case with main components such as embedded structure installation screw unit or the control unit to expose at the outside component of unmanned aerial vehicle during furthest reduces the flight, can solve unmanned aerial vehicle when flying around fruit tree or trees etc. by the problem that branch or other barriers hooked.

Also, the body 110 is hollow to receive fluid therein, has a streamline structure in the shape of an almond, thus reducing air resistance during flight, and can be made of a light material having a certain rigidity, such as plastic resin, aluminum material, etc., which is well known.

The outer shape of the main body 110 shown in fig. 1 is an example of having an oval structure as a whole, but is not limited thereto, and a cartridge having various structures may be used as the main body, and the main member of the unmanned aerial vehicle such as a propeller unit or a control unit described later may be embedded therein.

Referring to fig. 1 and 2, the structure of the body 110 according to an embodiment of the present invention is described as follows. The main body 110 includes: a fluid housing 111 having a space therein which can contain a fluid; a plurality of circular holes 112 formed in a structure penetrating the fluid housing 111; and a control room 113, which is a space part where the control unit 140 is installed in an embedded structure.

The fluid housing 111, as shown in fig. 1 and 2, is constructed to form a receiving space between the outside and the inside of the cartridge holding the outer bone, and preferably, as shown in fig. 2, the inner medicine receiving space is partitioned by at least one or more partition walls. This is to improve flight stability by minimizing a phenomenon that fluid flows inside due to acceleration or deceleration, direction change, and the like of the unmanned aerial vehicle during flight when the fluid is stored inside.

And, an upper portion of the fluid housing 111 forms a recessed mounting area to mount the control chamber 113 in an embedded structure. The control room 113 is provided with a battery 10 for supplying power to the electronic devices of the unmanned control plane 100, such as the propeller unit 120 and the jet unit 130, and the control unit 140. In this case, the battery 10 may be a known battery such as a disposable battery or a rechargeable lithium battery, and if a rechargeable battery is used, the battery may be detached from the control room 113 and separately charged, or the control room 113 may be charged through a power connector.

The control room 113 can be opened and closed by a cover 113a, and foreign matter is prevented from entering the control room 113 at ordinary times or when the unmanned control plane 100 is operating. In this case, it is preferable that the cover 113a is hinge-coupled to the control room 113 or provided to the control room 113 by a known fixing member such as a bolt. Further, the fluid housing 111 may be provided with an antenna 114 for receiving a driving signal of the drone 100 via a remote controller or a user terminal.

Further, an injection hole 115 is formed at an upper portion of the fluid housing 111 so that fluid can flow into the inside, and the injection hole 115 is opened and closed by a cover 115 a. The cover 115a is provided to the fluid housing 111 by hinge coupling or screw coupling.

The body 110 of the present invention has a plurality of circular holes 112 formed to penetrate the fluid housing 111. In an embodiment of the present invention, a 'circular hole' is defined as a through hole having a circular cross-section. However, this is only an example, but the 'circular hole' is not limited to the above definition as long as it can vertically penetrate the through-type structure of the body 110. The flow of air generated based on the operation of the propeller unit 120 disposed inside the circular hole 110 may function as a passage for freely moving the main body 110 up and down, and as long as an embedded type structure in which the propeller unit can be installed can be presented, it should be considered to be included in the above structure.

Further, in the embodiment of the present invention, the circular hole 112 is integrally formed in the fluid housing 111 by injection, forming a passage for burying an electric wire for transmitting power from the battery 10.

Also, the circular hole 112 includes a mounting portion coupled to or separated from the propeller unit 120, and the propeller unit is mounted to the inside of the circular hole in an insertion type.

In the unmanned aerial vehicle according to the embodiment of the present invention, when the circular hole 112 is formed in a cylindrical shape along the width direction of the fluid housing 111 based on the thrust generated by the rotation of the propeller 120, the flow of air based on the rotation of the propeller 120 is limited to a downward direction, thereby realizing the flight of the unmanned aerial vehicle 100.

The propeller unit 120 may be formed with a mesh-shaped protector (refer to 190 in fig. 10) on one side of the circular hole 112, and a steel or plastic resin material may be used, and the protector may be disposed on the circular hole 112 so as to be positioned above the propeller unit 120, thereby preventing the propeller unit 120 from being damaged by an unspecified obstacle such as a tree branch while the drone 100 is flying.

Fig. 3 shows the main component of the propeller unit 120 of fig. 1, i.e. the propeller.

As for the configuration of the propeller unit 120 according to the embodiment of the present invention, various known propeller configurations can be used, and thus, the present invention can be applied to any configuration as long as it can generate a flow of air from the upper portion to the lower portion to generate thrust when being installed in the circular hole 112 and rotated.

Fig. 4 is a conceptual diagram for describing the flight principle and direction change of the unmanned control plane of the present invention described above in fig. 1 to 3. As shown in fig. 4, the main body 110 of the unmanned control plane of the present invention is provided with a plurality of propeller units 120 in an embedded structure.

In this case, a part of the propeller units 120 moves the drone 100 forward and backward, and the remaining left and right move directions of the drone 100. For example, the four twin-screw units installed at the outer corners of the body 110 in an embedded type structure are controlled in rotation speed and operation to be lifted up and down, and the propeller units are adjusted in inclination to advance and retreat, and when moving left and right, thrust is formed in a direction in which the propeller units need to be moved, the rotation speed of the propeller units is controlled to form a difference in thrust.

Fig. 5 is a sectional view of the unmanned aerial vehicle with the spraying unit shown in fig. 1 as a reference, fig. 6 and 7 are sectional views of the nozzle part of fig. 5 showing a rotating state of the head, and fig. 8 is a sectional view a-a of fig. 6 and 7.

Referring to fig. 5, the injection unit 130 of the embodiment of the present invention includes: a nozzle portion 131 provided on an inner side surface of the body 110, one end of which is exposed to the outside of the body 110; an air pump 132 disposed inside the body 110 to inject external air into the nozzle portion 131; and a fluid inflow pipe 133 having one end portion disposed inside the body 110 and the other end portion disposed in the nozzle portion 131. In fig. 5, a pair of injection units is illustrated as an example, but not limited thereto, and as shown in fig. 4, a plurality of injection units 130 may be provided along a side surface of the body 110. In addition, in order to install the ejection units in the number required for the location and situation in accordance with the control mission of the unmanned aerial vehicle, the installation position can be changed at a plurality of places inside the main body.

As shown in fig. 6, the nozzle portion 131 of the injection unit 130 is connected to the air pump 132 and is provided in plurality along the outer corner edge direction of the fluid housing 111, and the nozzle portion 131 includes a plurality of heads 136 which are inclined at a certain angle with respect to a horizontal plane in the width direction of the main body.

In particular, referring to fig. 6, the fluid is ejected from the nozzle part 131 by an air positive pressure ejection method, the air supplied from the air pump 132 is supplied to the nozzle part 131 and moves, the fluid sucked through the fluid inflow pipe 133 rises to the nozzle part 131 based on the pressure generated by the flow of the moving air, and the fluid flowing into the nozzle part 131 collides with the air and is ejected in a spray form.

As shown in fig. 6, when the nozzle portion 136 of the head is directed upward, the fluid in the spray form is sprayed upward from the lower portion of the fruit tree to the upper portion, and the effective medicine spraying can be performed also for the fruits inside and outside the fruit tree, and the medicine can be sprayed to a wider range by the fluid spraying in the spray form.

For this, a plurality of the spray heads 136 are formed, and are disposed at the side of the fluid housing 111 at intervals in the direction of the fluid housing 111. The nozzle portion 131 is connected to the air pump 132, communicates with a flow path 135 for the inflow of the external air, and is formed as a head 136 inclined at a certain angle with respect to the width direction of the body 110.

The fluid inlet pipe 133 is connected to the center of the journal portion 135a through which the air in the flow passage 135 flows in the radial direction. That is, the fluid flows along the fluid inflow pipe 133 to enter the flow path 135a based on a pressure difference generated in the flow path 135a by a flow rate of the external air through the air discharge pipe 132b connected to the air pump 132, and the fluid entering the flow path 135a is mixed with the external air to be injected to the outside through the head 136. The shape of the journal portion 135a may be increased or decreased in various forms according to the pressure state of the air generated in the air pump 132.

Fig. 7 shows a state in which the head 136 is rotated to face downward in the structure in which the head 136 of the spray unit 130 of fig. 6 is positioned to face upward. Fig. 8 is a front view illustrating an operation state in which the head 136 is rotated in the spray unit 130 of fig. 6 and 7.

That is, the spray unit 130 of the present invention may further include a nozzle rotating part 137 that rotates the inlet to direct the exposure direction of the head 136 to an upper or lower portion.

In this case, the nozzle rotating part 137 includes: a rotary case 137a accommodating the head 136 and performing a rotating operation; a rotation motor 137b that provides power to rotate the rotation housing 137 a; and a rotation shaft 137c for transmitting a rotation force of the rotation motor 137 to the rotation housing 137 a. When the nozzle portion 131 sprays fluid (chemicals or the like) from the lower portion to the upper portion of the fruit tree based on the rotation of the rotary case 137a, the downward spraying can be realized by directing the head toward the lower portion as necessary even if the unmanned control plane of the present invention is used.

Also, as an optional member, a nozzle separating part 137d may be included, which is separated from the middle end 138 of the nozzle part 131 based on the rotation of the rotating housing 137 a.

Such a spraying unit may be disposed at a plurality of positions as shown in fig. 9, and in the unmanned control plane according to an embodiment of the present invention, the lower portion of the main body 110 may further include a landing unit 180. Such a shape or structure of the landing unit 180 is a structure that is not caught by an external obstacle, and as shown in fig. 5, a wheel structure may be formed at a lower portion of the main body 110, and in this case, a portion of the landing unit 180 is in a structure that is embedded inside the main body 110, thereby minimizing exposure, and a structure that can land or continue flying with minimized exposure even in the case of collision with the ground is employed.

The operation of the injection unit 130 of fig. 9 can be represented by a control unit (140 of fig. 1) including a communication unit for receiving driving signals of the propeller unit 120 and the injection unit 130 through a remote controller via the antenna 114, and an operation unit, and a known wireless system such as a wireless network or bluetooth may be used. In this case, the operation section performs driving of the respective members based on the driving signal received through the communication section. That is, the air pump (132 in fig. 2) is driven according to the forward or reverse direction driving signal of the propeller motor 124 to spray the fluid through the spray head (136 in fig. 6).

Fig. 10 is a perspective view of the protector combined with the upper or lower portion of the circular hole 112 of fig. 1, a of fig. 11 is a front view of the protector shown in fig. 10, b is a bottom view of the protector shown in fig. 10, and fig. 12 is a view showing a state where the protector of fig. 10 is combined with the circular hole.

As shown in fig. 10, the unmanned control plane of the present invention may further include: and a protector 190 coupled to an upper or lower portion of the circular hole (fig. 1: 112) and having a fluid hole 191a guiding a flow of air based on driving of the propeller unit. The protector 190 is a member for protecting the propeller unit 120 from being caught by an unspecified obstacle such as a tree branch.

In this case, the protector 190 includes: a protective cover 191 coupled to an upper end or a lower end of the circular hole 112; the partition wall 192 is extended in a plurality of plate-shaped structures spaced apart from each other in a diameter direction of the protective cover 191. The protective cover 191 has a plate shape corresponding to the diameter of the upper or lower end of the circular hole 112. The protective cover 191 has fluid holes 191a, and the partition 192 is formed along a diameter direction of the protective cover 191 such that air flowing along the circular hole 112 by the propeller 120 can pass through the protective cover 191.

That is, when the tree branches enter through the fluid hole 191a, the tree branches are hooked by the partition 192 at a uniform angle, and the tree branches are discharged outside the fluid hole 191a again as the unmanned aerial vehicle 100 moves, thereby protecting the propeller 120.

In particular, it is preferable that the plurality of partition walls 192 hold the fluid holes 191a and form an inclined angle with the surface of the protective cover 191. That is, as shown in fig. 10 to 12, the partition wall 192 is configured to protrude downward with reference to a virtual horizontal plane formed on the surface of the protective cover 191, and to protrude upward and downward with reference to a virtual horizontal plane formed on the surface of the protective cover 191.

In the configuration of fig. 10, the partition 192 is illustrated as protruding downward, but the present invention is not limited thereto, and may include a structure protruding upward with respect to a virtual horizontal plane formed on the surface of the protective cover 191.

That is, the plurality of partition walls 192 may be formed toward upper and lower directions of the inclined structure. This combination of structures is a very efficient structure, for example, when an obstacle such as a branch descending from the upper portion enters through the flow hole 191a of the protective cover 191, it is first hooked by the inclined structure of the partition wall, and it can be removed backward as it flies. Also, when the partition wall 192 has a structure protruding in an upper direction of the protective cover 191, it may be installed in a structure in which the partition wall 192 protrudes at a lower portion of the main body of the present invention, and in this case, the partition wall 192 exposed to the outside is structured such that an outer corner portion has a circular curvature, thereby being applied as a landing portion.

Referring to fig. 12, in the present invention, a placing portion 112a is concavely formed along a circumferential direction of a circular hole 112 formed in a body (fig. 1: 110) in a through-shaped structure at an upper end or a lower end of the circular hole 112, and a protector 190 is coupled to the circular hole 112. When the protective cover 191 is pulled by the fluid hole 191a, the protective cover 191 is separated from the placement portion 112a, and the protector 190 is separated from the circular hole 112.

As described above, according to the unmanned control plane of the present invention, a fluid including a chemical or the like is stored inside the main body without an additional tank and the tank is mounted to a structure required for the unmanned control plane. Further, the propeller unit is coupled to or separated from the main body, so that the propeller unit can be easily replaced and maintained. In addition, the ejection head expands the ejection range of the fluid by the upward or downward rotation of the ejection unit.

As described above, the preferred embodiments have been disclosed in the accompanying drawings and the description. Although specific terms are employed herein, they are used in a descriptive sense only and not for purposes of limitation or limitation of the scope of the invention as set forth in the claims. Accordingly, various modifications and equivalent other embodiments will be apparent to those skilled in the art. Therefore, the true technical scope of the present invention should be determined by the technical idea of the appended claims.

Claims

1. A unmanned control plane, comprising:

a body (110) containing a fluid therein;

a propeller unit (120) mounted in an embedded structure to a circular hole (112) formed in a structure penetrating the main body (110);

an injection unit (130) provided inside the main body (110) and having a nozzle section (131) that injects a fluid contained inside the main body (110); and

a control unit (140) disposed inside the main body (110) in an embedded structure, controlling driving of the propeller unit (120) and the injection unit (130).

2. The unmanned control plane of claim 1,

the main body (110) includes: a fluid housing (111) having a space therein which can contain a fluid;

a plurality of circular holes (112) formed in a structure penetrating the fluid housing (111); and

a control room (113) in the form of a space portion in which the control unit (140) is installed in an embedded structure.

3. The unmanned control plane of claim 2,

the injection unit (130) includes:

a nozzle unit (131) which is provided on the inner side surface of the main body (110) and one end of which is exposed to the outside of the main body (110);

an air pump (132) disposed inside the main body (110) and injecting outside air into the nozzle section (131); and

and a fluid inflow pipe (133) having one end portion disposed inside the main body (110) and the other end portion disposed in the nozzle portion (131).

4. The unmanned control plane of claim 3,

a plurality of the nozzle portions (131) are connected to the air pump (132) and arranged along the direction of the fluid housing (111),

the nozzle unit (131) includes a plurality of heads (136) that are disposed so as to be inclined at a predetermined angle with respect to a horizontal plane in the width direction of the main body.

5. The unmanned control plane of claim 4,

the nozzle part (131) adopts an air positive pressure injection mode,

the air supplied by the air pump (132) is supplied to the nozzle portion (131) to move,

the fluid sucked through the fluid inflow pipe (133) rises to the nozzle portion (131) based on the pressure generated by the flow of the moving air,

the fluid flowing into the nozzle portion (131) collides with the air and is sprayed in a spray pattern.

6. The unmanned control plane of claim 5,

the nozzle portion (131) further includes: and a nozzle rotating part (137) which rotates the inlet to direct the exposure direction of the nozzle (136) to the upper part or the lower part.

7. The unmanned control plane of claim 6,

the nozzle rotating portion (137) includes:

a rotary case (137a) accommodating the head (136) and performing a rotating operation;

a rotary motor (137b) that provides power to rotate the rotary housing (137 a);

and a rotating shaft (137c) that transmits the rotational force of the rotating motor (137) to the rotating housing (137 a).

8. The unmanned control plane of claim 2,

the unmanned control plane further includes a protection member (190) coupled to an upper or lower portion of the circular hole (112) and having a fluid hole (191a) for guiding a flow of air based on driving of the propeller unit.

9. The unmanned control plane of claim 8,

the protector (190) includes:

a protective cover (191) coupled to an upper end or a lower end of the circular hole (112);

and a plurality of partition walls (192) provided so as to protrude in the diameter direction of the protective cover (191).

10. The unmanned control plane of claim 9,

the partition wall (192) is formed on an upper surface or a lower surface of the protective cover (191).

11. The unmanned control plane of claim 10,

the plurality of partition walls (192) are provided in a structure of holding the flow holes (191a) and crossing the surface of the protection cover (191) at right angles or forming an acute inclination angle.