KR100548026B1 - Mask cleaner apparatus and screen printing apparatus provided with the same - Google Patents

Abstract

According to the present invention, there is provided a fixed block and a lifting block provided to be liftable relative to the fixed block; A supply roll shaft and a supply roll shaft rotatably installed on the lifting block; A paper roll for cleaning the mask surface wound around the feed roll shaft and the feed roll shaft and deployed therebetween; A blowing shaft installed on the lifting block and having a plurality of blowing holes formed on a circumferential surface thereof; A vacuum block installed at the lifting block and having a vacuum suction port; A docking pin formed to extend downward from a bottom of the fixing block; And a docking block having a docking groove into which the docking pin can be inserted, the docking block having a first direction moving unit and a second direction moving unit to enable a rectangular coordinate movement on a plane. Provided is a cleaning device for cleaning the lower surface of the mask for screen printing operation having a.

Description

Mask cleaner and screen printing apparatus provided with the same {Mask Clearner and Screen Printer With Same}

1 is a schematic perspective view of a screen printing apparatus with a mask cleaner apparatus according to the present invention.

2 is a partial perspective view showing only a part of the overall perspective view shown in FIG.

3 is an enlarged perspective view of a mask.

4 is a partial perspective view showing in detail the driving mechanism of the second moving block provided in the second direction moving unit.

FIG. 5 is a front view of the screen printing apparatus shown in FIG. 1.

FIG. 6 is a side view of the screen printing apparatus shown in FIG. 1.

7 and 8 are plan views of the screen printing apparatus shown in FIG. 1, wherein FIG. 7 shows an undocked state while FIG. 8 shows a docked state.

<Brief Description of Major Codes in Drawings>

1. Lower frame 2. Flat frame

3. vertical frame 4. horizontal frame

11. First direction moving unit 12. Second direction moving unit

13. Cleaning Device 15. Board Holding Unit

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mask cleaner device and a screen printing device having the same, and more particularly to a mask cleaner device for cleaning a cream solder attached to a mask used in a screen printing operation in which a cream solder is applied to a printed circuit board. And a screen printing apparatus having the same.

In general, in order to mount an electronic component on a printed circuit board, a screen printing operation of applying a cream solder to the surface of the substrate must be preceded. In the screen printing operation, the cream solder is selectively applied to a position on the substrate surface corresponding to the opening by applying the cream solder while the mask having the opening formed at a predetermined position is in close contact with the substrate surface. In such a screen printing operation, the surface of the mask which comes into close contact with the surface of the printed circuit board may be contaminated by cream solder partially due to the repeated screen printing operation.

If the surface of the mask in contact with the substrate surface is contaminated with cream solder, the screen printing operation is less accurate and the possibility of defective products is increased. This is because adhesion between the mask and the substrate is poor due to the thickness of the cream solder deposited on the mask surface, and therefore the cream solder is not properly applied at the correct position on the substrate surface.

In order to prevent contamination of the mask, a mask cleaner device is provided in an apparatus for performing a screen printing operation. The mask cleaner device may be provided in various forms. In general, the mask cleaner may be in close contact with the mask surface of the cleaning paper wound on a roller to perform a cleaning action. The mask cleaner apparatus is operated to temporarily stop the screen printing operation and to clean the mask surface during the repeated screen printing operation.

In the prior art, there is a problem that an operator cannot arbitrarily adjust the operating range of the mask cleaner device. The mask cleaner device of the prior art is set to be able to perform a cleaning operation on a fixed area on the mask surface, so that the cleaning operation is performed even on a portion where cleaning is not necessary at all. This unnecessary cleaning not only increases waste of time and power, but also wastes of consumables such as paper used for cleaning. In addition, since washing the parts that do not need cleaning, the intensive cleaning work for the area that needs to be cleaned can not be made, which leads to the problem that the cleaning efficiency is lowered.

 The present invention has been made to solve the above problems, it is an object of the present invention to provide an improved mask cleaner device.

Another object of the present invention is to provide a mask cleaner device that can be set so that the cleaning range can be arbitrarily defined and cleaned on the mask surface.

Another object of the present invention is to provide a screen printing apparatus having a mask cleaner device.

In order to achieve the above object, according to the present invention,

A fixed block and a lifting block provided to be movable on and off the fixed block;

A supply roll shaft and a supply roll shaft rotatably installed on the lifting block;

A paper roll for cleaning the mask surface wound around the feed roll shaft and the feed roll shaft and deployed therebetween;

A vacuum block installed at the lifting block and having a vacuum suction port;

A docking pin formed to extend downward from a bottom of the fixing block;

And a docking block having a docking groove into which the docking pin can be inserted.

The docking block is provided with a cleaning device for cleaning the lower surface of the mask for a screen printing operation comprising a; a robot having a first direction movement unit and a second direction movement unit to enable a rectangular coordinate movement on a plane.

According to one feature of the invention, the blower shaft is further provided with a plurality of blower holes formed in the lifting block is formed on the circumferential surface.

According to another feature of the present invention, there is further provided a cleaning liquid spray nozzle which can supply the cleaning liquid to the cleaning paper developed between the supply roll shaft and the supply roll shaft.

According to another feature of the invention, the docking between the docking block and the docking pin of the cleaning device is released while the cleaning device is not performing a cleaning operation.

According to another feature of the present invention, the first direction moving unit and the second direction unit further comprises a camera that performs a planar orthogonal coordinate movement and captures the lower surface of the mask.

According to another feature of the invention, the cleaning device performs cleaning only for a limited range of the lower surfaces of the mask based on the imaging data captured by the camera.

Also according to the invention,

A pair of horizontal frames;

A robot comprising a first direction moving unit movably installed in a first direction that is a longitudinal direction of the horizontal frame and a second direction unit movably installed in a second direction perpendicular to the first direction;

A substrate holding unit installed to be liftable with respect to a screen printing operation mask held between the horizontal frames and having a printed circuit board supported on a plurality of pins;

A docking block having an orthogonal coordinate movement by the robot and having a docking groove formed on one side thereof;

A fixed block provided with a docking pin that can be extended or contracted so as to be inserted into the docking groove, a lifting block provided to be liftable with respect to the fixed block, a supply roll shaft rotatably installed at the lifting block, and a feed roll shaft A paper roll for mask surface cleaning, which is wound around the supply roll shaft and the supply roll shaft, and is installed between the lifting roll shafts, a blow shaft installed in the lifting block, and having a plurality of blowing holes formed on a circumferential surface thereof, A cleaning device having a vacuum block having a suction port formed therein;

Provided is a screen printing apparatus for a printed circuit board, comprising: a camera configured to image a lower surface of the mask by performing a rectangular coordinate movement by the robot.

In addition, according to another feature of the present invention, the cleaning device is docked to the docking block only while performing the cleaning operation, the Cartesian coordinate movement, otherwise the docking is released to the standby state.

Hereinafter, with reference to an embodiment shown in the accompanying drawings the present invention will be described in more detail.

1 is a schematic perspective view of a screen printing apparatus with a mask cleaner apparatus according to the present invention.

Referring to the drawings, the screen printing apparatus includes a flat frame 2 disposed and mounted at a predetermined height on the lower frame 1, a vertical frame 3 installed at each corner of the flat frame, and the vertical frame 3 A pair of horizontal frames 4 arranged parallel to the ends of the &lt; RTI ID = 0.0 &gt; The substrate holding unit 15 is provided on the flat plate frame 2 so as to be movable up and down, and on one of the vertical frames 3, the cleaner device 13 is installed to be movable. The cleaner device 13 can be controlledly moved on the rectangular coordinates by docking with respect to the second direction moving unit 12 as described later.

On the other hand, the first direction moving unit 11 is installed to be movable along the pair of horizontal frames 4. In addition, the first direction moving unit 11 is provided so that the second direction moving unit 12 is movable along the longitudinal direction of the first direction moving unit 11. The first direction unit 11 and the second direction movement unit 12 constitute a robot that performs a rectangular coordinate movement on a plane.

2 is a partial perspective view showing only a part of the overall perspective view shown in FIG.

Referring to the drawings, a mask 15 is fixed between the pair of horizontal frames 4. The mask 15 performs screen printing in a fixed state between the horizontal frames 4, and may clean the lower surface of the mask 15 while the screen printing is interrupted. It is also possible to perform a squeegee operation on the upper surface of the mask 15 as will be described later. The mask 15 can be held in place by the mask pressurizing cylinder 61 and the brace portion 67 provided in the horizontal frame 4 as will be described later.

3 is an enlarged perspective view of a mask.

Referring to the drawing, openings 15a are formed in the mask 15, and solder may be screen printed on the substrate through the openings 15a. That is, when solder is printed from the upper surface of the mask 15 while the lower surface of the mask 15 is in contact with the upper surface of the substrate, the solder is printed only on a predetermined portion of the upper surface of the substrate through the opening 15a. It can be.

Referring back to FIG. 2, the first moving block 21 is installed on the upper portion of one of the horizontal frames 4 to be movable along the longitudinal direction of the horizontal frame 4. The first moving block 21 is installed to be movable along the first guide 25 installed in the horizontal frame 4. A first ball screw 23 is rotatably installed at one side of the horizontal frame 4, and the first ball screw 23 is coupled with a first nut 24 fixed to the first moving block 21. have. The first ball screw 23 may be rotated by a driving force provided from the first drive motor 22 installed on the horizontal frame 4. Power of the first drive motor 22 is transmitted to the first ball screw 23 by the transmission means not shown in the figure. The transmission means can be, for example, a gear train, a timing belt and a pulley. As a result, the power of the first drive motor 22 can reciprocally controllably control the first moving block 21 provided in the first direction unit 11 in the first direction.

The third drive motor 31 is provided above the horizontal frame 4. The rotational force of the third drive motor 31 is transmitted to the third ball screw 32 via the transmission means. The third ball screw 32 is coupled to a third nut, not shown in the figure, which is installed in a squeegee means not shown in the figure. The squeegee means is intended to evenly apply the solder by pressing the solder on the surface of the mask which is not in contact with the substrate. Squeegee means will not be described in detail as they are not included in the present invention. The squeegee block 34 included in part of the squeegee means is movably installed along the third guide 33 provided on the horizontal frame 4.

The second moving block 26 is installed in the first moving block 21 so as to be movable in the longitudinal direction of the first moving block 21. The second moving block 26 is provided in the second direction unit 12, and the movement directions of the first moving block 21 and the second moving block 22 are perpendicular to each other. The second moving block 26 is provided with a docking block 41, which may be docked with the cleaner device 13 by docking with a docking pin (not shown) provided in the cleaner device 13. . The docking operation is only performed when the cleaning of the mask surface in contact with the substrate is required, otherwise the cleaner device 13 is waiting in the waiting block 53. That is, the washing operation can be performed only when the docking block 41 is docked with the cleaner device 13.

The drawing shows a docking groove 42 formed on one side of the docking block 41. A docking pin (not shown), which can enter from the top of the docking groove 42, is provided at the bottom of the cleaner device 31, and the docking pin (not shown) is provided with a pneumatic cylinder installed together at the bottom of the cleaner device 31. The action of (not shown) is to allow entry into or exit of the docking groove 42. Therefore, the docking action of the cleaner device 13 can be made only when necessary.

As shown in the drawing, the cleaner device 13 is provided with a lifting block 52 to elevate on an upper portion of the fixing block 51, and the lifting block 52 has a paper roll 54 and a vacuum block 59. And a blowing shaft 55 are provided. A lifting cylinder (not shown) is provided between the fixed block 51 and the lifting block 52, so that the lifting block 52 can be lifted and operated. This lifting action allows at least a portion of the cleaning paper provided on the paper roll 54 provided in the lifting block 51 to contact the lower surface of the mask 15. That is, the lifting block 51 is raised after the cleaner device 13 reaches the lower part of the mask 16 so that the cleaning paper can contact the lower surface of the mask 15 to perform the cleaning operation.

The paper roll 54 is wound around a supply roll shaft 56 (FIG. 6) and a supply roll shaft 57 (FIG. 7) rotatably installed in the lifting block 52 in which cleaning paper provided in the form of a roll is rolled. Will be. The paper roll 54 is unwound from the feed roll shaft 56 and wound onto the feed roll shaft 57, between which a flat surface of the cleaning paper is developed, which flat surface contacts the bottom of the mask 15. This makes it possible to carry out the cleaning operation.

In the cleaning operation, it is preferable to spray the cleaning liquid on the cleaning paper. The cleaning liquid may be supplied to the cleaning paper through a cleaning liquid spray nozzle (not shown). The cleaning liquid spray nozzle is installed on one side of the elevating block 52 so that it can be sprayed even during the cleaning operation, or one side of the horizontal frame 4 so that it can be sprayed when the cleaner device 13 is on the standby block 53. It can be installed on.

The lifting shaft 52 is provided with a blowing shaft 55. The blowing shaft 55 is a hollow cylinder in which a plurality of blowing holes are formed on the circumference. The blowing shaft 55 may be connected to a blowing tube (not shown) to receive air. Air may be discharged through the blow holes formed in the blow shaft 55 to be injected onto the bottom of the mask 15. The air discharged from the blow shaft 55 may serve to dry the cleaning liquid delivered to the surface of the mask 15 during the cleaning operation. The cleaning paper runs through the lower portion of the blow shaft 55.

The lifting block 52 is also provided with a vacuum block 59. In the example shown in the figure, the vacuum block 59 is provided at the bottom of the cleaning paper that is flatly developed. The vacuum suction port is formed on the upper portion of the vacuum block 59, and the force of the vacuum generated through the vacuum suction port assists the cleaning action of the cleaning paper. In other words, the cleaning paper allows for better adhesion of contaminants on the cleaning paper during the cleaning operation.

4 shows in detail the drive mechanism of the second moving block provided in the second directional moving unit.

Referring to the drawings, it can be seen that the second moving block 26 is installed to be movable in the second direction with respect to the first moving block 21. As can be clearly seen in FIG. 4, the first moving block 21 accommodates a second drive motor 27, a second ball screw 28, and the like for reciprocating the first moving block 26. It limits space for doing so. The second moving block 26 may guide and reciprocate along the second guide 30 installed extending in the longitudinal direction of the first moving block 21. In addition, the second nut 29 fixed to the second moving block 26 is coupled to the second ball screw 28 rotatably installed on the first moving block 21. The second ball screw 28 may rotate by receiving a rotational force from the second driving motor 27 through a transmission means (not shown). As a result, the rotational driving force of the second drive motor 27 can reciprocate the second moving block 26 in the second direction.

In FIG. 4, the second moving block 26 is docked with the cleaning device 13. Therefore, the cleaning device 13 can not only reciprocate in the second direction according to the reciprocating motion of the second moving block 26, but also reciprocate in the first direction according to the reciprocating motion of the first moving block 21. I can understand that I can.

Meanwhile, the camera / nozzle bracket 60 is fixed to the second moving block 26. A lifting cylinder 49 is installed in the camera nozzle bracket 60, and the camera 62 and the nozzles 46 (FIG. 5) are lifted and mounted by the lifting cylinder 49. The camera 62 is for imaging the lower surface of the mask 15, and the nozzle 46 is for picking up the substrate support pin 42. The camera 62 and the nozzle 46 will be described later in more detail.

In addition, the feed roll shaft 56 and the feed roll shaft 57 are installed in parallel to the lifting block 52 of the washing device 13, and the cleaning paper is provided while being wound around the shafts 56 and 57. It can be seen that. The rotation of the feed roll shaft 57 is provided with a drive motor (not shown) so that the cleaning paper can be wound from the feed roll shaft 56 to the feed roll shaft 57. The vacuum block 59 and the blow shaft 55 described above are also shown.

5 shows a front view of the screen printing apparatus shown in FIG.

Referring to the drawings, the first moving unit 11 is provided to reciprocate with respect to the horizontal frame 4. In addition, the docking block 41 fixed to the second moving block 26 of the second mobile unit 12 is shown in Fig. 5 in an undocked state with the cleaning device. The nozzle 46 provided to be elevated on the camera / nozzle bracket 60 of the second moving block 26 is provided to arrange the pin 42 at a predetermined position on the pin plate 43. This will be described in more detail below with respect to the operation of the substrate holding unit 15.

The substrate holding unit 15 includes an elevating plate 41 provided to be capable of elevating, a pin plate 43 provided on the elevating plate 41, and the elevating plate 41 at one side of the pin plate 43. And a pin waiting plate 45 fixed on the top. The pin plate 43 is provided with a plurality of pins 42, which may be moved to a predetermined position of the pin plate 43 by the action of the nozzle 46 described above. The pin 42 may be fixedly held at a predetermined position by inserting a lower end of the pin into a hole formed in the pin plate 43, and the upper end of the pin 42 supports a lower surface of a printed circuit board (not shown). Will be supported. The pins 42 can be appropriately supported by the substrates having different diameters. The nozzle 46 performs the operation of moving and placing the pin 42 between the pin waiting plate 45 and the pin plate 43, which is connected to the first moving unit 11 described above. By the action of the second moving unit 12, a rectangular coordinate movement can be performed on the plane, and the pin 42 can be lifted up or down by a lifting cylinder provided therein. The elevating plate 41 may be elevated by a cylinder or a drive motor (not shown).

Shown in FIG. 6 is a side view of the screen printing apparatus shown in FIG. 1.

Referring to the drawings, the mask 15 is held by a brace 67 mounted to the horizontal frame 4, the edge of the upper surface of the mask 15 being pressed by the pressure cylinder 61. As can be seen in FIG. 1, the pressure cylinder 61 may be provided in plural horizontal frames 4. The mask 15 can be stably maintained by the action of the brace part 67 and the pressure cylinder 61.

A lifting cylinder 49 is provided at the camera nozzle bracket 60, and the nozzle 46 and the camera 62 may be lifted and lowered by the lifting cylinder 49. The camera 62 is for imaging the bottom surface of the mask 15, and can determine the area which the washing | cleaning apparatus 13 should wash with the data acquired by imaging. As such, when the cleaning operation is performed only on the area based on the information obtained by the imaging, the time required for the cleaning operation, power, and the consumption of the consumable including the cleaning liquid may be reduced. In addition, the nozzle 46 can be lowered close to the pin waiting plate 45 by the lifting cylinder 49, and the pin can be moved by arranging itself as described above.

7 and 8 show the screen printing apparatus of FIG. 1 as a plan view, and FIG. 7 shows the docking apparatus and the docking state, and FIG. 8 shows the washing apparatus and the docking state. .

Referring to FIG. 7, the second direction moving unit 12 is separated from the washing device 13. The second direction movement unit 12 may perform Cartesian coordinate movement on the plane for the operation of the camera 62 or the nozzle 46.

Referring to FIG. 8, the second direction moving unit 12 is docked with the cleaning device 13. The second direction movement unit 12 may cause the cleaning device 13 to reach the lower part of the mask 15, and as described above, the second direction moving unit 12 may move the second block in the state where the lifting block 52 is lifted and raised in the cleaning device 13. When the direction unit 12 is moved, a predetermined washing operation may be performed.

Hereinafter, the screen printing action and the cleaning action made in the screen printing apparatus according to the present invention will be described schematically.

In order to perform the screen printing operation on the printed circuit board, first, the mask 15 is fixed in place in the preparation step, and the board supporting pins capable of holding the printed circuit board are disposed on the pin plate 43. The mask 15 is fixed by placing the mask 15 over the brace 67 and pressing the mask 15 with the pressure cylinder 61. In addition, the nozzle 46 moves the pin 42 from the pin standby plate 45 to the pin plate 43 so as to be disposed.

A printed circuit board (not shown) is then placed over the top end of the pins 42 supported on the pin plate 43. Typically a printed circuit board can be supplied using a conveyor belt, but this is known and will not be described herein any further.

Next, the lifting plate 41 is raised to bring the printed circuit board into close contact with the bottom surface of the mask 15. When the cream solder is applied from the upper surface of the mask 15 with the mask 15 and the printed circuit board approaching each other, the cream solder is applied to a predetermined portion of the printed circuit board through the opening 15a of the mask 15. do. Next, the lifting plate 41 is lowered and the printed circuit board is discharged.

As the number of repetitions of the screen printing operation as described above increases, the bottom surface of the mask 15 is contaminated with cream solder. To clean the contaminated portion, first, data on the contaminated area is obtained by imaging with the camera 62.

The docking of the cleaning device 13 is then made. Docking to the cleaning device 13 is accomplished by inserting a docking pin (not shown) into the docking groove 42 formed in the docking block 41 as described above. The docking pin is provided at the lower end of the fixing block 51 of the washing device 13, and is capable of being extended or contracted by a cylinder (not shown) provided at the fixing block 51.

The cleaning device 13 may reach the bottom of the mask 15 in the docked state. Next, as the lifting block 52 is raised, the washing paper developed from the paper roll 54 can be in close contact with the bottom surface of the mask 15. The cleaning paper is provided with a cleaning liquid.

In the state where the cleaning paper is in close contact with the bottom of the mask 15, the cleaning device 13 performs the rectangular coordinate movement by the action of the first and second directional moving units 11 and 12, and the lower part of the mask 15. The surface can be cleaned. The dirt generated in the cleaning operation may be introduced through the inlet of the vacuum block 59, and the cleaning liquid remaining on the bottom of the mask 15 is dried by the air blown from the blow shaft 55.

When the cleaning operation is completed, the lifting block 52 is lowered and the cleaning device 13 is returned to the position of the waiting block 53 again. Thereafter, the docking is released and the interrupted screen printing operation may be repeated.

The washing apparatus and the screen printing apparatus according to the present invention have an advantage that the washing operation and the printing operation can be performed more quickly and efficiently. In particular, the cleaning area can be controlled based on the information obtained from imaging of the lower surface of the mask, thereby reducing the time, power, and use of consumables such as cleaning paper and cleaning liquid required for cleaning. In addition, since the cleaning operation can be performed automatically, screen printing can be performed more quickly and efficiently, and the quality of the printed printed circuit board can be improved.

Although the present invention has been described with reference to one embodiment shown in the accompanying drawings, this is only illustrative, and it will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible. Could be. Therefore, the true scope of protection of the present invention should be defined only by the appended claims.

Claims (8)

A fixed block and a lifting block provided to be movable on and off the fixed block; A supply roll shaft and a supply roll shaft rotatably installed on the lifting block; A paper roll for cleaning the mask surface wound around the feed roll shaft and the feed roll shaft and deployed therebetween; A vacuum block installed at the lifting block and having a vacuum suction port; A docking pin formed to extend downward from a bottom of the fixing block; And a docking block having a docking groove into which the docking pin can be inserted. And the docking block includes a robot having a first direction moving unit and a second direction moving unit to enable a rectangular coordinate movement on a plane. The method of claim 1, The apparatus for cleaning the lower surface of the mask for screen printing operation, characterized in that it further comprises a blowing shaft is installed on the lifting block and a plurality of blowing holes on the circumferential surface. The method of claim 1, The cleaning apparatus for cleaning the lower surface of the mask for screen printing operation, characterized in that the cleaning liquid spray nozzle for supplying the cleaning liquid to the cleaning paper developed between the supply roll shaft and the supply roll shaft. The method of claim 1, The docking device between the docking block and the docking pin of the cleaning device is released while the cleaning device is not performing the cleaning operation, cleaning device for cleaning the lower surface of the mask for screen printing operation. The method of claim 1, Washing for cleaning the lower surface of the mask for screen printing work, characterized in that it further comprises a camera for performing a rectangular Cartesian motion by the first direction moving unit and the second direction unit, the image of the lower surface of the mask. Device. The method of claim 5, And the cleaning device performs cleaning only for a limited range of the lower surfaces of the mask based on the imaging data picked up by the camera. A pair of horizontal frames; A robot comprising a first direction moving unit movably installed in a first direction that is a longitudinal direction of the horizontal frame and a second direction unit movably installed in a second direction perpendicular to the first direction; A substrate holding unit installed to be liftable with respect to a screen printing operation mask held between the horizontal frames and having a printed circuit board supported on a plurality of pins; A docking block having an orthogonal coordinate movement by the robot and having a docking groove formed on one side thereof; A fixed block provided with a docking pin that can be extended or contracted so as to be inserted into the docking groove, a lifting block provided to be liftable with respect to the fixed block, a supply roll shaft rotatably installed at the lifting block, and a feed roll shaft A paper roll for mask surface cleaning, which is wound around the supply roll shaft and the supply roll shaft, and is installed between the lifting roll shafts, a blow shaft installed in the lifting block, and having a plurality of blowing holes formed on a circumferential surface thereof, A cleaning device having a vacuum block having a suction port formed therein; And a camera which photographs a lower surface of the mask by performing a rectangular coordinate movement by the robot. The method of claim 7, wherein And the cleaning device is docked to the docking block only while the cleaning operation is performed, thereby performing Cartesian coordinate movement. Otherwise, the docking device is released and placed in a standby state.

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