JP2000340084A - High-frequency relay - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-frequency relay wherein high-frequency noise leaking to the outside is reduced. SOLUTION: A relay body 1 is composed of a body and a box-like synthetic resin cover 22 overlaid on the body and having one surface opened. A coil and contact parts of which contact state is switched according to the current carrying to the coil are received in the relay body 1, and plural terminals 17-19 project sideward from the lower surface of the relay body 1. A box-like metal case 2 having one surface opened is overlaid on the relay body 1, and a grounding terminal 3 projecting downward is protrusively formed on the open edge of the metal case 2. Thus, when the relay body 1 is mounted on a board, the grounding terminal 3 formed on the metal case 2 is electrically connected to the earth line of the board.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-frequency relay.

[0002]

2. Description of the Related Art FIG. 13A is a top view of a conventional high-frequency relay in which a part is broken, and FIG.
FIG. 13C shows a cross-sectional view taken along the line BB ′, and FIG. 13D shows a cross-sectional view taken along the line CC ′.

This relay is a seesaw type relay in which the contact is opened and closed using an electromagnet device in which an amateur operates in a seesaw operation. A coil 12 is wound around a central piece of a substantially U-shaped iron core 11 and the iron An electromagnet device 10 having a structure in which a permanent magnet 13 is disposed between the distal ends of the two leg pieces, and a strip-shaped armature 14 is swingably supported at an intermediate portion of the permanent magnet 13. The permanent magnet 13
Are magnetized to the same magnetic pole at both ends of the iron core 11 facing the two leg pieces, and magnetized to different magnetic poles at the intermediate part.
Numeral 4 swings bistable between positions in contact with one leg of the iron core 11 in response to energization of the coil 12.

[0004] Here, movable contact springs 15 are respectively arranged along both side surfaces in the longitudinal direction of the armature 14, and an intermediate portion of the movable contact spring 15 is attached to the armature 14 by a spring support 16 made of synthetic resin. They are joined together. A hinge spring 15b is continuously and integrally connected to an intermediate portion of the movable contact spring 15 in the longitudinal direction, and movable contacts 15a are provided at both ends, respectively.
With the swing of 4, each movable contact 15a comes into contact with and separates from a fixed contact 18a fixed at a fixed position of the body 20.

Incidentally, the electromagnet device 10, a common terminal 17 electrically connected to the hinge spring 15b, a contact terminal 18 having a fixed contact 18a at an end thereof, and a coil 12
A coil block 19 is molded with a synthetic resin with the coil terminal 19 electrically connected to the body block 21 to form a body block 21. The body block 21 is covered with a substantially box-shaped synthetic resin cover 22 that is open on one side. I have. Here, the relay block 1 is composed of the body block 21 and the cover 22.
Each of the terminals 17 to 19 is disposed along a side surface of the body 20 in the longitudinal direction, and has a tip bent at a substantially right angle.
It protrudes laterally from the opening edge of the cover 20.
Thus, the relays are electrically and mechanically connected to the mounting substrate by surface-mounting the tips of the terminals 17 to 19 on a mounting substrate (not shown).

Here, when the armature 14 is swung according to the energization of the coil 12, the movable contact 15a provided at the tip of the movable contact spring 15 comes into contact with and separates from the fixed contact 18a. By electrically connecting to the common terminal 17, a relay having a switching contact (transfer contact) using the movable contact 15a as a common contact can be configured. The hinge springs 15b, 15b
Is twisted when the amateur 14 swings,
The elastic force is generated to return the amateur 14.

[0007]

The high-frequency relay having the above structure is driven by a high-frequency signal. However, a high-frequency signal (noise) leaks to the outside from a contact portion including the fixed contact 18a and the movable contact 15a, and the hinge spring 15b, Alternatively, since a high-frequency signal (noise) leaks outside via the hinge spring 15b and the armature 14, there is a problem that high-frequency characteristics are deteriorated.

There is also a high-frequency relay in which a metal case is placed directly on the body 20 instead of the cover 22 to prevent a high-frequency signal from leaking from the contact portion, the hinge spring 15b and the armature 14 to the outside. Since the cover 20 is not provided and the metal case is directly covered on the body 20, there is a problem that it is difficult to seal the inside of the relay.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a high-frequency relay in which high-frequency noise leaking to the outside is reduced.

[0010]

In order to achieve the above object, according to the first aspect of the present invention, a coil and a contact portion whose contact state switches according to energization of the coil are housed therein.
It is composed of a relay body provided with mounting terminals for mounting on a board, and a metal case covering the surface of the relay body, wherein the metal case is provided with a ground terminal for grounding to a ground line of the board. Since the metal case that covers the surface of the relay body is grounded to the ground line of the board via the ground terminal, high-frequency signals (high-frequency noise) leaking from the relay body to the outside are dropped to the ground line of the board via the metal case. High frequency characteristics can be improved.

According to a second aspect of the present invention, in the first aspect of the present invention, a fixing piece for fixing the relay body to the metal case by engaging with the peripheral surface of the relay body is provided on the metal case. By locking the fixing piece provided on the case to the peripheral surface of the relay main body, the relay main body can be securely fixed to the metal case.

According to a third aspect of the present invention, in the first aspect of the present invention, the relay body is substantially box-shaped, the metal case is formed in a substantially box shape opened on one side, and the ground terminal is formed at an opening edge of the metal case. It is characterized by being provided at the four corners, and the ground terminals are provided at the four corners of the opening edge of the metal case, so the mounting terminals of the relay body can be mounted by the ground terminals provided at the four corners no matter where the mounting terminals are located. High-frequency signals leaking from the terminals to the outside can be reliably dropped to the ground line, high-frequency signals leaking to the outside can be efficiently reduced, and high-frequency characteristics can be improved.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the relay body is provided with a plurality of mounting terminals, and one or more ground terminals are arranged between adjacent mounting terminals. Is provided in a metal case, and the ground terminal is arranged between adjacent mounting terminals, so that leakage of high-frequency signals between mounting terminals can be dropped to the ground line by the ground terminal. And high frequency characteristics can be improved.

According to a fifth aspect of the present invention, in the first aspect of the present invention, the mounting terminal comprises a surface mounting terminal, and the grounding terminal is provided on a metal case for fixing the relay body to the metal case. When the relay body is fixed to the metal case by bending the fixing piece and locking it to the peripheral surface of the relay body, the surfaces of the fixing piece and the mounting terminals facing the substrate are substantially flush with each other. In the state where the fixing piece is bent and the relay body is fixed to the metal case, the surfaces of the fixing piece and the mounting terminal facing the substrate are substantially flush with each other. When the surface is mounted on the substrate, the fixing piece can be electrically connected to the ground line of the substrate. Therefore, since the grounding terminal can be shared by the fixing piece, there is no need to separately provide the grounding terminal and the fixing piece in the metal case, and the structure of the metal case can be simplified,
In addition, since it is only necessary to bend the fixing piece, the fixing of the relay body and the grounding of the metal case can be easily performed.

According to a sixth aspect of the present invention, in the first aspect of the present invention, the ground terminal comprises a terminal for a through hole inserted into a through hole formed in the substrate.
It can also handle the case where the relay body is a through-hole type,
Since the soldering surface of the mounting terminal of the relay body and the soldering surface of the ground terminal are on the same surface of the substrate, the soldering operation can be performed at a time.

According to a seventh aspect of the present invention, in the first to sixth aspects of the present invention, the metal case is formed by drawing, and since the metal case is formed by drawing, the metal case has a gap. Therefore, high-frequency signals leaking to the outside from the gap can be reduced, and high-frequency characteristics can be improved.

[0017]

Embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1) A high-frequency relay according to this embodiment will be described with reference to FIGS. The high-frequency relay according to the present embodiment includes a coil and a contact part whose contact state switches according to the energization of the coil. The relay body includes terminals (mounting terminals) 17 to 19 for mounting on a substrate. 1 and a metal case 2 attached to the relay body 1. Since the relay body 1 has the same configuration as the conventional relay shown in FIG. 13 described above, the description thereof will be omitted. As described in the conventional example, the relay main body 1 is configured by covering the body 20 with the cover 22. By filling the lower surface of the body 20 with a sealant (not shown), the body 20 and the cover 22 are separated from each other. The inside of the enclosed relay can be sealed.

The metal case 2 is formed by punching, dividing, and bending a sheet metal having conductivity, thereby forming a substantially box-like shape having one open surface. A protruding ground terminal 3 is provided.

Then, as shown in FIG.
When surface mounting is performed on the mounting substrate 30, the ground terminal 3 of the metal case 2 is electrically connected to an earth line (not shown) provided on the mounting substrate 30 by soldering or the like, and the metal case 2 is connected to the mounting substrate 30. Ground line. Here, the metal case 2 is attached to the relay main body 2 so as to cover the cover 22 of the relay main body 2, the portions of the terminals 17 to 19 disposed on the side surface of the body 20, the hinge spring 15 b, and the amateur. 14 is covered by the metal case 2, the contact portion, the hinge spring 15b and the amateur 1
4 can be dropped to the ground line of the mounting board 30 through the metal case 2,
High frequency signals (noise) leaking to the outside can be reduced, and high frequency characteristics can be improved.

(Embodiment 2) A high-frequency relay according to this embodiment will be described with reference to FIGS. In the high-frequency relay according to the present embodiment, in the high-frequency relay according to the first embodiment, a pair of substantially L-shaped grounding terminals 3 are protruded at both ends of the opening edge on both side surfaces in the longitudinal direction of the metal case 2 and are short. At both ends of the opening edge on both sides in the width direction,
Fixing piece 4 for fixing relay body 1 to metal case 2
Are protruded one by one. The ground terminal 3 and the fixing piece 4
The other configuration is the same as that of the first embodiment, and therefore, the same components are denoted by the same reference numerals and description thereof will be omitted.

Here, as shown in FIGS. 3B and 4, after the metal case 2 is put on the relay body 1, the fixing piece 4 provided on the metal case 2 is bent inward, and the relay body 1 is bent. The relay main body 1 is securely fixed to the metal case 2 by engaging with the lower surface of the relay.

When the relay body 1 is surface-mounted on the mounting board 30, the ground terminal 3 of the metal case 2 is electrically connected to an earth line provided on the mounting board 30 by soldering or the like. It is grounded to the ground line of the mounting board 30. By the way, the ground terminal 3 and the relay body 1
In some cases, grounding cannot be reliably performed depending on the positional relationship with the terminals 17 to 19, but in this embodiment, since the grounding terminals 3 are provided at the four corners of the opening edge of the metal case 2,
Regardless of the position of the terminals 17 to 19 of the relay body 1, the high frequency signal (noise) leaking from each of the terminals 17 to 19 to the outside is mounted on the mounting substrate 3 by the four ground terminals 3.
0 can be efficiently dropped to the ground line, and high frequency characteristics can be improved.

(Embodiment 3) A high-frequency relay according to this embodiment will be described with reference to FIG. In the high-frequency relay of the present embodiment, in the high-frequency relay of the second embodiment, fixing pieces 4 for fixing the relay body 1 to the metal case 2 are provided at both ends of the opening edges on both side surfaces in the short width direction of the metal case 2. A pair of terminals 17 to 1 adjacent to the relay main body 1 are provided at the opening edges on both sides in the longitudinal direction.
9, a plurality of (for example, six) substantially L-shaped ground terminals 3 are provided so as to be interposed between them. Since the configuration other than the ground terminal 3 is the same as that of the second embodiment, the same components are denoted by the same reference numerals and description thereof will be omitted.

In this embodiment, a plurality of ground terminals 3 are provided so as to be interposed between the adjacent terminals 17 to 19 of the relay main body 1, and each ground terminal 3 is soldered to the ground line of the mounting board 30. Since the terminals are electrically connected to each other, a high-frequency signal leaking directly from the terminals 17 to 19 to the outside can be dropped to the ground line of the mounting board 30 via the metal case 2, and a high-frequency signal (noise) leaking to the outside
And the high frequency characteristics can be improved.

(Embodiment 4) A high-frequency relay according to this embodiment will be described with reference to FIGS. In the high-frequency relay of the present embodiment, in the high-frequency relay of the first embodiment, a pair of fixing pieces 5 project from both ends of the opening edge on both sides in the short width direction of the metal case 2. Since the configuration other than the fixing piece 5 is the same as that of the first embodiment, the same components are denoted by the same reference numerals and description thereof will be omitted.

Here, as shown in FIGS. 6 (b) and 7, after the metal case 2 is put on the relay body 1, the tip of the fixing piece 5 provided on the metal case 2 is bent inward, and the relay body 1 is bent. By engaging with the lower surface of the relay 1, the relay body 1 is securely fixed to the metal case 2. Also, the fixing piece 5
Is bent, and the terminals 17 to 19 of the relay body 1 and the surfaces of the fixing pieces 5 facing the mounting board 30 are substantially flush with each other in a state where the relay body 1 is fixed to the metal case 2. When the surface is mounted on the mounting board 30, the fixing piece 5 is electrically connected to the ground line of the mounting board 30, and the metal case 2 is grounded to the ground line of the mounting board 30 by the fixing piece 5.

As described above, in the high-frequency relay of the present embodiment, the fixing piece 5 also serves as a ground terminal for grounding the metal case 2 to the ground line of the mounting board 30.
There is no need to separately provide the ground terminal and the fixing piece on the metal case 2, and the structure of the metal case 2 can be simplified as compared with the case where the ground terminal 3 and the fixing piece 4 are separately provided as in the second embodiment. In addition, since it is only necessary to bend the fixing piece 5, the fixing of the relay body 1 and the grounding of the metal case 2 can be easily performed.

(Embodiment 5) A high-frequency relay according to this embodiment will be described with reference to FIGS. In the high-frequency relay of each of the above-described embodiments, the relay body 1 is surface-mounted on the mounting board 30. In the present embodiment, in the high-frequency relay of the second embodiment, the through-hole provided on the mounting board 30 of the relay body 1 is used. Terminals 17 to 19 for through holes to be inserted into 31 are provided.

Here, the metal case 2 is formed by punching, dividing, and bending a conductive plate material. Both ends of the opening edge on both sides in the longitudinal direction of the metal case 2 are formed. A pair of substantially bar-shaped grounding terminals 3 ′ to be inserted into through holes 31 provided in the mounting board 30 are provided one by one, and the relay main body 1 is provided with a metal case at both ends of the opening edges on both side surfaces in the short width direction. A pair of fixing pieces 4 for fixing to 2 are projected. The ground terminal 3 '
Structures other than the above are the same as those of the second embodiment, and therefore, the same components are denoted by the same reference numerals and description thereof will be omitted.

When soldering the relay body 1 to the mounting board 30, the terminals 17 to 19 and the ground terminal 3 'of the relay body 1 are inserted into the through holes 31 provided in the mounting board 30. By soldering, the relay body 1
Can be electrically connected to the mounting board, and the metal case 2 can be grounded to the ground line of the mounting board 30, so that high-frequency signals leaking to the outside can be reduced and high-frequency characteristics can be improved.

The terminals 17 to 19 of the relay body 1
Is a through-hole terminal, and if the metal case 2 is provided with the grounding terminal 3 for surface mounting as in the second embodiment described above, the board to which the terminals 17 to 19 of the relay body 1 are soldered Is different from the surface of the substrate to which the ground terminal 3 is soldered.
Is provided with a grounding terminal 3 'for through-holes, so that the relay body 1 can be easily adapted to a through-hole type, and the surface of the board to which the terminals 17 to 19 of the relay body 1 are soldered is connected to the grounding terminal. The surface of the substrate to which 3 'is soldered is the same surface, and the soldering operation can be easily performed.

In the high frequency relay of the present embodiment,
As shown in FIGS. 10A and 10B, a plurality of grounding terminals are arranged between opening edges on both side surfaces in the longitudinal direction of the metal case 2 and between adjacent terminals 17 to 19 of the relay main body 1. 3 ′ may be protrudingly provided, and by electrically connecting each ground terminal 3 ′ to the ground line of the mounting board 30,
High-frequency signals leaking directly from the terminals 17 to 19 to the outside can be dropped to the ground line of the mounting board 30 via the metal case 2, and high-frequency signals leaking to the outside can be reduced, and high-frequency characteristics can be improved.

(Embodiment 6) A high-frequency relay according to this embodiment will be described with reference to FIGS. In the high-frequency relay of each of the above-described embodiments, since the metal case 2 is formed by punching, dividing, and bending a sheet metal having conductivity, the minute gaps 2a are formed between the respective side surfaces of the metal case 2. And high frequency signals may leak from the gap 2a. Therefore, in the high-frequency relay of the present embodiment,
In the high-frequency relay according to the second embodiment, the metal case 2 is formed by drawing. Since the configuration of the high-frequency relay other than the metal case 2 is the same as that of the second embodiment, the same components are denoted by the same reference numerals and description thereof will be omitted.

As described above, in this embodiment, the metal case 2
Is formed by drawing, so that a minute gap is generated between the side surfaces of the metal case 2 as in the case of forming the metal case 2 by punching, dividing, and bending a sheet metal. There is no high frequency signal (noise) leaking from the minute gap between each side,
High frequency signals (noise) leaking to the outside can be reduced, and high frequency characteristics can be improved. The metal case 2 of the present embodiment may be used for the high-frequency relays of the first and third to fifth embodiments described above, and a high-frequency signal (noise) leaking to the outside is reduced in the same manner as described above to improve the high-frequency characteristics. be able to.

The material of the metal case 2 is, for example, MB115 alloy (product number of Mitsubishi Electric Corporation) which is a nickel-based alloy containing copper, nickel and zinc as main components.
And has better corrosion resistance, conductivity, and solderability than conventional nickel silver such as C7521 (product number of Mitsubishi Electric Corporation).

[0037]

As described above, according to the first aspect of the present invention, the coil and the contact portion whose contact state switches according to the energization of the coil are housed inside, and the mounting terminal for mounting on the substrate is provided. And a metal case that covers the surface of the relay body.The metal case covers the surface of the relay body. Grounded to the ground line via the ground terminal, so that high-frequency signals (high-frequency noise) leaking from the relay body to the outside can be dropped to the ground line on the board via the metal case.
There is an effect that high frequency characteristics can be improved.

According to a second aspect of the present invention, in the first aspect of the present invention, a fixing piece for fixing the relay body to the metal case by engaging with the peripheral surface of the relay body is provided on the metal case. By locking the fixing piece provided on the case and the peripheral surface of the relay main body, there is an effect that the relay main body can be securely fixed to the metal case.

According to a third aspect of the present invention, in the first aspect of the invention, the relay body is substantially box-shaped, the metal case is formed in a substantially box-like shape having an open surface on one side, and the ground terminal is formed at the opening edge of the metal case. It is characterized by being provided at the four corners, and the ground terminals are provided at the four corners of the opening edge of the metal case, so the mounting terminals of the relay body can be mounted by the ground terminals provided at the four corners no matter where the mounting terminals are located. The high frequency signal leaking from the terminal to the outside can be reliably dropped to the ground line, and the high frequency signal leaking to the outside can be efficiently reduced, and the high frequency characteristics can be improved.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the relay body has a plurality of mounting terminals,
One or more ground terminals are provided in the metal case so as to be arranged between adjacent mounting terminals,
Since the ground terminal is arranged between the adjacent mounting terminals, the leakage of the high-frequency signal between the mounting terminals can be dropped to the ground line by the ground terminal, and the high-frequency characteristics can be improved.

According to a fifth aspect of the present invention, in the first aspect of the present invention, the mounting terminal comprises a surface mounting terminal, and the ground terminal is provided on a metal case for fixing the relay body to the metal case. When the relay body is fixed to the metal case by bending the fixing piece and locking it to the peripheral surface of the relay body, the surfaces of the fixing piece and the mounting terminals facing the substrate are substantially flush with each other. In the state where the fixing piece is bent and the relay body is fixed to the metal case, the surfaces of the fixing piece and the mounting terminal facing the substrate are substantially flush with each other. When the surface is mounted on the substrate, the fixing piece can be electrically connected to the ground line of the substrate. Therefore, since the grounding terminal can be shared by the fixing piece, there is no need to separately provide the grounding terminal and the fixing piece in the metal case, and the structure of the metal case can be simplified,
In addition, since it is only necessary to bend the fixing piece, there is an effect that the fixing of the relay body and the grounding of the metal case can be easily performed.

According to a sixth aspect of the present invention, in the first aspect of the present invention, the ground terminal comprises a terminal for a through hole inserted into a through hole formed in the substrate, and the relay body is of a through hole type. In this case, the soldering surface of the mounting terminal of the relay body and the soldering surface of the ground terminal are on the same surface of the substrate, so that there is an effect that the soldering operation can be performed at once.

According to a seventh aspect of the present invention, in the first to sixth aspects of the present invention, the metal case is formed by drawing, and since the metal case is formed by drawing, a gap is formed in the metal case. Thus, there is an effect that high-frequency signals leaking to the outside from the gap can be reduced and high-frequency characteristics can be improved.

[Brief description of the drawings]

1A and 1B show a high-frequency relay according to a first embodiment, wherein FIG. 1A is a perspective view showing a state before assembly, and FIG. 1B is an external perspective view after assembly.

FIG. 2 is a diagram illustrating a state in which the high-frequency relay is mounted on a board.

3A and 3B show a high-frequency relay according to a second embodiment, in which FIG. 3A is a perspective view showing a state before assembly, and FIG. 3B is an external perspective view after assembly.

FIG. 4 is a diagram illustrating a state in which the high-frequency relay is mounted on a board.

5A and 5B show a high-frequency relay according to Embodiment 3, wherein FIG. 5A is a perspective view showing a state before assembly, and FIG. 5B is an external perspective view after assembly.

6A and 6B show a high-frequency relay according to a fourth embodiment, in which FIG. 6A is a perspective view showing a state before assembly, and FIG. 6B is an external perspective view after assembly.

FIG. 7 is a diagram illustrating a state in which the high-frequency relay is mounted on a board.

8A and 8B show a high-frequency relay according to a fifth embodiment, in which FIG. 8A is a perspective view showing a state before assembly, and FIG. 8B is an external perspective view after assembly.

FIG. 9 is a diagram illustrating a state in which the high-frequency relay is mounted on a board.

10A and 10B show another high-frequency relay of the above, wherein FIG. 10A is an external perspective view and FIG. 10B is a side view.

11A and 11B show a high-frequency relay according to Embodiment 6, in which FIG. 11A is a perspective view showing a state before assembly, and FIG. 11B is an external perspective view after assembly.

FIG. 12 is a diagram illustrating a state in which the high-frequency relay is mounted on a board.

13A and 13B show a conventional high-frequency relay, wherein FIG. 13A is a top view partially broken, FIG. 13B is a cross-sectional view taken along line AA ′, and FIG.
FIG. 6D is a cross-sectional view taken along the line B-B ′, and FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Relay body 2 Metal case 3 Grounding terminal 17-19 terminal 22 Cover

Claims (7)

[Claims] 1. A relay body in which a coil and a contact portion whose contact state switches according to energization of the coil are housed, and a relay body provided with mounting terminals for mounting on a board, and a metal covering a surface of the relay body. A high-frequency relay comprising a case, and a metal case provided with a ground terminal for grounding to a ground line of the substrate. 2. The high-frequency relay according to claim 1, wherein a fixing piece for fixing the relay main body to the metal case by engaging with the peripheral surface of the relay main body is provided on the metal case. 3. The relay body is substantially box-shaped, the metal case is formed in a substantially box-like shape with one open side, and ground terminals are provided at four corners of an opening edge of the metal case. 2. The high-frequency relay according to 1. 4. The relay body is provided with a plurality of mounting terminals, and a plurality of mounting terminals are arranged between adjacent mounting terminals.
The high-frequency relay according to claim 1, wherein a plurality of ground terminals are provided on the metal case. 5. The mounting terminal comprises a surface mounting terminal,
The grounding terminal is composed of a fixing piece provided on the metal case to fix the relay body to the metal case, and the fixing piece is bent and locked to the peripheral surface of the relay body to connect the relay body to the metal case. 2. The high-frequency relay according to claim 1, wherein, in the fixed state, the surfaces of the fixing pieces and the mounting terminals facing the substrate are substantially flush. 6. The high frequency relay according to claim 1, wherein the ground terminal comprises a terminal for a through hole inserted into a through hole formed in the substrate. 7. The high-frequency relay according to claim 1, wherein the metal case is formed by drawing.