KR102597143B1 - Cleaning head of ultrasonic cleaner - Google Patents

Abstract

The present invention improves the structure of the discharge passage that sprays air on the surface of the object to be cleaned without installing a separate ultrasonic oscillator, and improves cleaning power by oscillating ultrasonic waves with various frequencies by controlling the amount of supplied air. By assembling the upper duct, lower duct, and inner duct with bolts, disassembly for assembly and maintenance of the cleaning device is easy, and a second suction hole for secondary suction is formed on the outside of the first suction hole. The purpose is to provide a cleaning head of an ultrasonic cleaning device that can significantly increase suction efficiency by suctioning contaminants that separate and scatter from the surface of the object to be cleaned.

Description

Cleaning head of ultrasonic cleaner}

The present invention relates to a dry cleaning device, and more specifically, to ultrasonic cleaning, which can improve cleaning power by oscillating ultrasonic waves by improving the structure of the discharge passage that sprays air on the surface of the object to be cleaned without installing an ultrasonic oscillation device. It concerns the cleaning head of the device.

Because display panels, glass substrates, or wafers are manufactured through many processes, various contaminants are attached to the surface, so they necessarily undergo a cleaning process to remove contaminants after processing. Cleaning methods can be broadly classified into wet cleaning and dry cleaning. Wet cleaning is a cleaning method that sequentially goes through organic cleaning, cleaning with pure water, inorganic cleaning, and drying steps. Additionally, dry cleaning is a method of cleaning non-stick contaminants by floating them in a non-contact manner.

The dry cleaning device sprays clean air on the surface of the object to be cleaned while passing it through a narrow passage, separates and disperses particles attached to the surface of the object, and suctions the floating particles to clean the object. This is a device that removes contaminants attached to the surface of water. In order to increase cleaning power, ultrasonic waves are oscillated by passing air through a narrow channel. Patent registration No. 2207537, “Dry Cleaning,” covers the flow path structure of a dry cleaning device that can oscillate ultrasonic waves through the flow of air without a separate ultrasonic oscillation device. It is presented in “Device”. However, in order to increase particle removal efficiency, it is necessary to oscillate ultrasonic waves through the flow of air sprayed on the surface of the object to be cleaned and simultaneously improve the flow rate of the discharged air. The patent has a simple flow path structure, which increases the flow rate significantly. There is a problem that it cannot be improved and ultrasonic waves with various frequencies cannot be oscillated.

In addition, the technology presented in Patent Registration No. 2039530 "Cleaning Head" surrounds an inner duct equipped with an air jet that sprays clean air onto the surface of the object to be cleaned with a lower cover, and an exhaust duct is connected to the upper part of the lower cover. It is constructed by combining the upper duct, and the upper cover, lower cover, inner duct, and lower cover are each connected by a slide guide with a concavo-convex structure. However, the patent

First, it is a structure in which the upper cover, lower cover, inner duct, and lower cover are each joined by a slide guide with an uneven structure. Since the length of the slide guide is long (the length of the guide is usually about 1 to 3 m), two members It is very difficult and inconvenient to combine, and when disassembly is required for repair or maintenance, there is a problem that it is even more inconvenient and difficult to disassemble.

Second, since the air jet that sprays clean air onto the surface of the object to be cleaned is not structured to generate ultrasonic waves, the cleaning power is inevitably very weak, so there is a problem of low cleaning efficiency.

Third, since the air suction hole (suction hole) through which contaminants separated from the surface of the object to be cleaned and scattered are suctioned is formed close to the air injection port, the suction efficiency is not high, so the contaminants flying away from the surface of the object to be cleaned are not high. There is a problem that contaminants that cannot be suctioned spread into the work space, causing secondary contamination.

The present invention was developed to solve the above problems, and the purpose of the present invention is to improve the structure of the discharge passage that sprays air on the surface of the object to be cleaned without installing a separate ultrasonic oscillator, and to improve the structure of the discharge passage to spray air on the surface of the object to be cleaned without separately installing an ultrasonic oscillator. The purpose is to provide a cleaning head of an ultrasonic cleaning device that can improve cleaning power by oscillating ultrasonic waves with various frequencies by controlling the amount.

Another object of the present invention is to facilitate assembly and disassembly for maintenance of the cleaning device by assembling the upper duct, lower duct, and inner duct with bolts, and to install a second suction hole for secondary suction on the outside of the first suction hole. The purpose of this invention is to provide a cleaning head for an ultrasonic cleaning device that can significantly increase suction efficiency by forming a hole to suction contaminants flying away from the surface of the object to be cleaned.

In the cleaning head of the ultrasonic cleaning device according to the present invention, air supplied from the outside through an air supply duct stays inside the pressure chamber, and then blows onto the surface of the object to be cleaned through an air injection hole formed along the longitudinal direction in the lower center of the pressure chamber. an internal duct through which air is sprayed, and first suction holes are formed on both sides of the air injection hole; The cross-section is formed in a square shape with the bottom open, and is arranged to surround the inner duct, forming a suction buffer zone in the space spaced between the square-shaped inner circumferential surface and the inner duct. A lower cover having a square-shaped upper surface formed with a first exhaust port for exhausting the suctioned air that has passed through the suction buffer zone; The cross-section is formed in a square shape with the lower part open, and is coupled to the upper part of the lower cover. A suction zone is formed in the square-shaped inner space, and the first It is configured to include an upper cover through which the suctioned air passing through the exhaust port stays in the suction zone and is then discharged to the outside through the exhaust duct. A nozzle unit is inserted into the lower part of the pressure chamber, and the air passing through the nozzle unit is Ultrasonic waves are oscillated and sprayed through the air injection hole, and the inner duct is coupled to the lower cover, and the lower cover is coupled to the upper cover by bolts.

Preferably, the pressure chamber has a square cross-section, and at the upper part of the square shape, a connection portion is formed along the longitudinal direction to protrude vertically to the upper surface of the lower cover, and a bolt is connected to the connection portion from the top of the lower cover. are joined by fastening, and the central portion of the square-shaped bottom surface forming the pressure chamber protrudes downward by a certain width along the longitudinal direction, and the protruding portion protrudes downward by a certain height in the vertical direction into which the nozzle unit is inserted. It forms a space for the nozzle unit insertion part, and an air injection hole is formed on the bottom surface of the nozzle unit insertion part. Concealment plates are formed to protrude in the horizontal direction on both sides of the bottom surface of the nozzle unit insertion part, so that the ends of each concealment plate ( As the lower part of both side walls of the lower cover and the lower cover are connected by bolts, the concealment plate closes the open lower part of the lower cover, and a first suction hole is formed in each concealment plate.

Preferably, a gap-maintaining shaft is inserted into the upper part of the nozzle unit insertion space to enable the nozzle unit insertion part to maintain a space of a certain width, and the nozzle unit is inserted into the space formed in the lower part of the gap-maintaining shaft at the nozzle unit insertion part. It is inserted and installed.

Preferably, the nozzle unit includes first and second nozzle bodies formed as a pair of corresponding shapes and installed to face each other; It is inserted and fixedly installed between the first and second nozzle bodies, and a slit is formed between the first and second nozzle bodies to maintain a constant shape so that the slit becomes a flow path through which air flows. It is configured to include a fixed shaft, and the flow path is formed to have an arrow shape with a conical cross-section from the top to the bottom, and air flows from the pressure chamber into the upper flow path located at the top of the arrow shape. , the lower flow path located at the bottom of the arrow shape is installed to be connected to the air injection hole, the slit width of the upper flow path is formed to be larger than the slit width of the lower flow path, and the fixed shaft is installed in the cone-shaped portion, A gap-maintaining protrusion is formed to protrude on either side of the first or second nozzle body, and the protruding gap-maintaining protrusion maintains the slit width of the lower flow path, and the upper part of the gap-maintaining protrusion in the lower flow path. Alternatively, an ultrasonic generator with a rectangular cross-section larger than the slit width of the lower flow path is installed at the lower part.

Preferably, the lower portions of both side walls of the lower cover are each double bent inward to form a step, and a cover is attached to the lower cover to create a secondary suction space open downward outside the double bent portion. is formed, and a second exhaust port penetrating into the suction buffer zone is formed in the double bent part, and the open lower part of the space of the secondary suction part becomes a second suction hole to suction air, and the second suction part is formed. The air suctioned through the hole stays in the secondary suction part and is discharged to the suction buffer zone through the second exhaust port.

Preferably, inside the suction buffer zone, protrusions are formed on the inner wall of the lower cover, and protrusions are also formed on the outer wall of the inner duct at opposing positions to reduce the flow rate of the suctioned air passing between the protrusions. will increase.

Preferably, the amount of air supplied from the air supply duct is controlled to adjust the amount of air supplied to the air chamber and sprayed through the nozzle unit to generate ultrasonic waves having various frequencies.

The ultrasonic cleaning device according to the present invention improves the structure of the discharge passage that sprays air on the surface of the object to be cleaned, and controls it to adjust the amount of air supplied, thereby oscillating ultrasonic waves with various frequencies to remove various types of contaminants. Because it can be removed effectively, cleaning power can be significantly improved without installing a separate ultrasonic oscillator.

In addition, disassembly for assembly and maintenance of the cleaning device is easy by assembling the upper duct, lower duct, and inner duct by fastening them with bolts, and a second suction hole for secondary suction is formed outside the first suction hole to avoid By suctioning contaminants that separate and scatter from the surface of the cleaning product, it can increase cleaning efficiency and exert a soundproofing effect by absorbing ultrasonic sound.

Figure 1 is a perspective view showing a cleaning device according to the present invention.
FIG. 2 is a cross-sectional view taken along line AA in FIG. 1.
Figure 3 is an enlarged view of the nozzle unit portion in Figure 2.
Figure 4 is a diagram showing the direction in which air sprayed from the cleaning device onto the surface of the object to be cleaned is suctioned and discharged.

The technical features of the ultrasonic cleaning device according to the present invention are that it improves the structure of the discharge passage that sprays air on the surface of the object to be cleaned without installing an ultrasonic oscillator, and oscillates ultrasonic waves with various frequencies by controlling the amount of supplied air. In addition, the cleaning efficiency was significantly increased by forming a second suction hole for secondary suction on the outside of the first suction hole to suction contaminants flying away from the surface of the object to be cleaned. am.

The dry cleaning device of the present invention is a cleaning device that separates contaminants such as dust attached to the surface of the object to be cleaned by spraying air containing ultrasonic waves on the surface of the object to be cleaned, and suctions and removes contaminants scattered in the sprayed air. . The cleaner head of the cleaning device includes an internal duct 30 through which clean air flows in from the outside, a lower cover 20 surrounding the internal duct 30 and into which suctioned air flows in, and a lower cover 20. ) It is configured to include an upper cover 10 that is coupled to the upper part and discharges the suctioned air to the outside (see Figure 2). A motor (not shown) is installed outside the cleaning head to supply clean air to the internal duct 30 through the air supply duct 40, and to the upper cover 10 through the exhaust duct 40'. ), it creates a suction force that can suction air by forming a vacuum.

The inner duct 30 is connected to the lower cover 20, and the lower cover 20 is connected to the upper cover 10 by bolts. Since they are connected by bolts, they are used for assembly and maintenance of the cleaning device. Disassembly is simple and convenient.

The internal duct 30 is a duct in which air supplied from the outside through the air supply duct 40 stays inside the pressure chamber 31, which is the internal space of the internal duct, and is formed along the longitudinal direction in the lower center of the pressure chamber 31. Air is sprayed at high pressure on the surface of the object to be cleaned through the air injection hole 34, and on both sides of the air injection hole 34, there are first suction holes ( 361) are formed and composed respectively. A nozzle unit 35 is inserted into the lower part of the pressure chamber 31, and ultrasonic waves are oscillated in the air passing through the nozzle unit 35 and are sprayed onto the surface of the object to be cleaned through the air injection hole 34.

The lower cover 20 is formed in a square-shaped cross-section with the lower part open, and is arranged to surround the internal duct 30, forming a square-shaped inner peripheral surface and an internal duct ( 30), a suction buffer zone (21) is formed in the space between them, and the suctioned air that has passed through the suction buffer zone (21) is formed on the square-shaped upper surface forming the lower cover (20). A first exhaust port 23 for exhausting air is formed. The suction buffer zone 21 is located on the movement path of the suctioned air, and changes the cross-sectional area with protrusions formed on the inner peripheral surface to increase the suction attraction force by increasing the flow speed.

The upper cover 10 is formed in a square-shaped cross-section with the lower part open, and the open part is coupled to the upper part of the lower cover 20, and the suction zone is in the square-shaped internal space. ) (11) is formed so that the suctioned air that has passed through the suction buffer zone (21) and the first exhaust port (23) stays in the suction zone (11) and is then discharged to the outside through the exhaust duct (40'). do.

The pressure chamber 31 has a square cross-section, and at the top of the square shape, a connection portion 32 is formed along the longitudinal direction to protrude vertically to the upper surface of the lower cover 20, so that the lower cover ( 20) is fixedly coupled by fastening bolts to the connection portion 32 at the top.

The central portion of the square-shaped bottom surface forming the pressure chamber 31 protrudes downward by a certain width along the longitudinal direction, and the protruding portion protrudes downward by a certain height in the vertical direction to form a nozzle into which the nozzle unit 35 is inserted. A space is formed for the unit insertion part 33, and an air injection hole 34 is formed on the bottom of the nozzle unit insertion part 33. In addition, plate-shaped concealing plates 36 are formed to protrude in the horizontal direction on both sides of the bottom surface of the nozzle unit insertion portion 33, so that the end portions and lower covers of each concealing plate 36 are formed. As the lower portions of both side walls of (20) are fastened and coupled with bolts, the concealment plate (36) closes the open lower part of the lower cover (20), and each concealment plate (36) has air sprayed on the surface of the object to be cleaned. A first suction hole 361 is formed to suction.

A gap maintenance shaft 352 is inserted into the upper part of the nozzle unit insertion part 33 space, allowing the nozzle unit insertion part 33 to maintain a space of a certain width. The nozzle unit 35 is a nozzle unit insertion part ( 33), it is inserted and installed into the space formed in the lower part of the gap maintenance shaft 352. Insert the gap maintenance shaft 352 between both side walls of the nozzle unit insertion part 33, place the plates 354 on the outside of both side walls of the nozzle unit insertion part 33, and then maintain the gap at the plate 354. If the position of the gap maintenance shaft 352 is fixed by fastening the bolt to the shaft 352, the nozzle unit insertion part 33 can maintain a space of a certain width. The gap maintenance shafts 352 are installed at equal intervals along the longitudinal direction of the nozzle unit insertion portion 33 in the pressure chamber 31.

The nozzle unit 35 is a pair of first and second nozzle bodies 351 and 351', and a fixed shaft ( 353), the nozzle unit 35 is manufactured as one unit and is inserted into the nozzle unit insertion part 33 and installed (see FIG. 3).

The first and second nozzle bodies (351, 351') are formed as a pair of corresponding shapes and are installed to face each other. There is a fixed device between the first and second nozzle bodies (351, 351'). The shaft 353 is inserted and fixedly installed, and a slit is formed between the first and second nozzle bodies 351 and 351', and the fixed shaft 353 is inserted and installed so that the slit is a passage through which air flows. It allows the flow path to maintain a certain shape.

The flow path is formed to have an arrow-shaped space with a cone-shaped cross section from the top to the bottom, and air flows into the upper flow path located at the top of the arrow shape from the pressure chamber 31, and is shaped like an arrow. The end of the lower flow path located at the bottom is installed to be connected to the air injection hole 34, and the upper flow path and lower flow path are respectively installed at the top and bottom of the cone shape and each has a slit shape with a certain width. Since the slit width of the flow path is formed to be larger than the slit width of the lower flow path, the flow rate of air passing through the lower flow path becomes much faster than the flow rate of air passing through the upper flow path.

The fixed shaft 353 is installed in a cone-shaped portion, and a gap maintenance protrusion 355 is formed to protrude integrally with the nozzle body on one side of the first or second nozzle body 351, 351', so that the protruding The ends of the gap maintenance protrusions 355 are supported on the nozzle body installed to face each other, thereby maintaining the slit width of the lower flow path. Gap maintaining protrusions 355 are installed at equal intervals along the longitudinal direction of the lower flow path.

The characteristic structure for ultrasonic oscillation in the cleaning device of the present invention is the first and second ultrasonic wave generators 356, which have a rectangular cross-section, on the upper and/or lower part of the gap maintenance protrusion 355 in the lower flow path. 357), where the first and second ultrasonic wave generators (356, 357) are spaces formed much larger than the slit width of the lower flow passage, so that the air flowing in the lower flow passage suddenly expands the width of the slit in the ultrasonic generator. As this space is formed, a vortex phenomenon occurs, causing vibration, and at this time, ultrasonic waves are oscillated. It is desirable that the second ultrasonic wave generator 357 be formed on the lower surface of the nozzle unit 35 and be directly connected from the second ultrasonic wave generator 357 to the air injection hole 34, which is the slit width of the lower flow path. This is because it is difficult to accurately match the air injection hole 34 and the flow path because it is very narrow.

In this way, the air passing through the upper flow path flows into the cone-shaped arrow-shaped part, changing the flow rate, and with the flow rate further increased due to the inclined surface of the cone, it flows into the lower flow path from the bottom outlet of the cone, and the lower flow As it passes through the furnace, the cross-section suddenly increases at the ultrasonic generator and a vortex is formed. The flow speed increases again and the vortex formation process is repeated, causing ultrasonic waves to be oscillated.

Another technical feature of the dry cleaning device according to the present invention is that it is provided with a secondary suction unit 242 to increase cleaning efficiency and soundproofing effect. The lower portions of both side walls of the lower cover 20 are double bent inward to form a single stage, and a cover 241 is attached from the unbent part of the lower cover 20 to the bottom, so that the cover ( The inner surface of the 241) and the outer surface of the double-bent portion form a secondary suction portion 242 space open downward, and the double-bent portion has a second exhaust port 244 penetrated through the suction buffer zone 21. ) are formed at regular intervals (see Figure 3).

The open lower part of the space of the secondary suction unit 242 becomes the second suction hole 243 to suction air mixed with contaminants that was not suctioned in the first suction hole 361, and the second suction hole 243 is opened. Air mixed with contaminants suctioned through stays in the secondary suction unit 242 and is discharged to the suction buffer zone 21 through the second exhaust port 244. The space of the secondary suction unit 242 also functions to remove noise generated during suction and noise generated during ultrasonic oscillation, so it also has a soundproofing effect.

Inside the suction buffer zone 21, a protrusion 22 is formed on the inner wall of the lower cover 20, and a protrusion (not specified in the drawing) is formed on the outer wall of the inner duct 30 at an opposing position. It is desirable to give, as the cross-sectional area narrows between the opposing protrusions, increasing the flow rate of the suctioned air passing between the protrusions, thereby increasing the suction power.

In addition, by controlling the amount of air supplied from the air supply duct 40, the amount of air supplied to the air chamber 31 and injected through the nozzle unit 35 is controlled to generate ultrasonic waves with various frequencies. It will be done. Since various types of contaminants are attached to the surface of the object to be cleaned, cleaning efficiency can be increased by adjusting the frequency of ultrasonic waves according to the type of contaminants.

The above description is an illustrative description of the present invention, and the embodiments published in the specification are not intended to limit the technical idea of the present invention, but are for illustrative purposes, so those skilled in the art Various modifications and variations will be possible without departing from the technical idea of . Therefore, the scope of protection of the present invention should be interpreted based on the matters stated in the claims, and technical matters within the equivalent scope thereof should also be interpreted as being included in the scope of rights of the present invention.

10: Upper cover 11: Suction zone
20: lower cover 21: suction buffer zone
22: Protrusion 23: First exhaust port
24: step portion 241: cover
242: 2nd suction part 243: 2nd suction hole
244: 2nd exhaust port
30: internal duct 31: pressure chamber
32: Connection part 33: Nozzle unit insertion part
34: air injection hole 35: nozzle unit
351, 351': first and second nozzle bodies 352: gap maintenance shaft
353: fixed shaft 354: plate
355: Gap maintaining protrusion 356: First ultrasonic wave generator
357: Second ultrasonic wave generator
36: Concealment plate 361: First suction hole
40: air supply duct 40': exhaust duct

Claims (7)

In a cleaning device that sprays air on the surface of an object to be cleaned, separates contaminants such as dust attached to the surface of the object to be cleaned, and removes contaminants scattered in the sprayed air by suction,
The cleaner head of the cleaning device is,
Air supplied from the outside through the air supply duct stays inside the pressure chamber, and then the air is sprayed onto the surface of the object to be cleaned through the air injection hole formed along the longitudinal direction in the lower center of the pressure chamber, and air is sprayed on both sides of the air injection hole. Internal ducts each formed with a first suction hole;
The cross-section is formed in a square shape with the bottom open, and is arranged to surround the inner duct, forming a suction buffer zone in the space spaced between the square-shaped inner circumferential surface and the inner duct. A lower cover having a square-shaped upper surface formed with a first exhaust port for exhausting the suctioned air that has passed through the suction buffer zone;
The cross-section is formed in a square shape with the lower part open, and is coupled to the upper part of the lower cover. A suction zone is formed in the square-shaped inner space, and the first An upper cover where the suctioned air passing through the exhaust port stays in the suction zone and is then discharged to the outside through the exhaust duct;
It is composed including,
A nozzle unit is inserted into the lower part of the pressure chamber, and ultrasonic waves are oscillated in the air passing through the nozzle unit and are sprayed through the air injection hole.
The inner duct is connected to the lower cover, and the lower cover is connected to the upper cover by bolts, respectively,
The nozzle unit is,
First and second nozzle bodies formed as a pair of corresponding shapes and installed to face each other;
It is inserted and fixedly installed between the first and second nozzle bodies, and a slit is formed between the first and second nozzle bodies to maintain a constant shape so that the slit becomes a flow path through which air flows. fixed shaft;
It is composed including,
The flow path is formed to have an arrow shape with a conical cross-section from the top to the bottom, and air flows from the pressure chamber into the upper flow path located at the upper part of the arrow shape, and the lower part located at the lower part of the arrow shape. The flow path is installed to be connected to the air injection hole, and the slit width of the upper flow path is formed to be larger than the slit width of the lower flow path.
The fixing shaft is installed in a cone-shaped portion, and a gap maintenance protrusion is formed to protrude on either side of the first or second nozzle body, and the protruding gap maintenance protrusion maintains the slit width of the lower flow path. ,
A cleaning head of an ultrasonic cleaning device, characterized in that an ultrasonic generator having a rectangular cross-section and being formed to be larger than the slit width of the lower flow path is installed on the upper or lower part of the gap maintenance protrusion in the lower flow path.
According to paragraph 1,
The pressure chamber has a square cross-section, and at the top of the square shape, a connection part protrudes vertically along the longitudinal direction to the upper surface of the lower cover, and a bolt is fastened from the top of the lower cover to the connection part. are combined,
The central portion of the square bottom surface forming the pressure chamber protrudes downward by a certain width along the longitudinal direction, and the protruding portion protrudes downward by a certain height in the vertical direction to form a nozzle unit insertion space into which the nozzle unit is inserted. An air injection hole is formed on the bottom of the nozzle unit insertion part,
Concealment plates are formed to protrude horizontally from both sides of the bottom surface of the nozzle unit insertion portion, so that the end of each concealment plate and the lower part of both side walls of the lower cover are fastened with bolts to connect the concealment plate to the open side of the lower cover. A cleaning head of an ultrasonic cleaning device, characterized in that the lower part is closed and a first suction hole is formed in each concealment plate.
According to paragraph 2,
A gap maintenance shaft is inserted into the upper part of the nozzle unit insertion space to maintain a space of a certain width, and the nozzle unit is inserted and installed into the space formed at the lower part of the gap maintenance shaft at the nozzle unit insertion area. A cleaning head of an ultrasonic cleaning device, characterized in that:
delete According to paragraph 1,
The lower portions of both side walls of the lower cover are each double bent inward to form a step, and the cover is attached to the lower cover to form a secondary suction space open downward outside the double bent portion. The double bent portion is formed with a second exhaust port penetrating the suction buffer zone,
The open lower part of the secondary suction part space becomes the second suction hole to suction air, and the air suctioned through the second suction hole stays in the secondary suction part and is discharged to the suction buffer zone through the second exhaust port. A cleaning head of an ultrasonic cleaning device, characterized in that:
According to paragraph 1,
Inside the suction buffer zone, protrusions are formed on the inner wall of the lower cover, and protrusions are also formed on the outer wall of the inner duct at opposing positions, increasing the flow rate of suctioned air passing between the protrusions. A cleaning head of an ultrasonic cleaning device, characterized in that.
According to paragraph 1,
Cleaning of the ultrasonic cleaning device, wherein the amount of air supplied from the air supply duct is controlled to adjust the amount of air supplied to the air chamber and sprayed through the nozzle unit, thereby generating ultrasonic waves with various frequencies. head.

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