Dual-magnetic noise reduction earphone and control method thereof

Abstract

The present invention relates to the field of earphone technology, and in particular to a dual-magnetic noise reduction earphone and a control method thereof, comprising an earphone holder; both ends of the earphone holder are provided with a telescopic frame; one end of a fixed part is provided with a push rod for abutting against the earphone holder; the other end of the fixed part is provided with a body; the body is provided with a first diaphragm; a accommodating cavity is formed between the first diaphragm and the body; a driving unit is provided in the accommodating cavity; a lifting bracket is provided for lifting and lowering activities in the accommodating cavity; a permanent magnet is provided at the top of the lifting bracket; a second diaphragm is provided at the bottom of the first diaphragm; a magnetorheological fluid is provided between the first diaphragm and the second diaphragm; a transmission mechanism is provided between the push rod and the lifting bracket. The present invention adjusts the extension and retraction of the telescopic frame according to the size of the user's head, thereby driving the lifting bracket to drive the permanent magnet to move up and down, and uses the second permanent magnet to change the stiffness of the magnetorheological fluid, thereby limiting the amplitude of the first diaphragm, controlling the volume output, and preventing excessive volume from damaging the hearing of child users.

Description

Technical Field

[0001] The present invention relates to the technical field of earphones, and in particular to a dual-magnetic noise reduction earphone and a control method thereof. Background Art

[0002] Earphones are a conversion unit that usually has one or two speakers. They receive electrical signals from a media player or receiver and convert them into audible sound waves using speakers close to the ears. With the popularity of consumer electronic devices, earphones have been widely used in devices such as video games, mobile phones, live webcasts, computers, and digital audio players.

[0003] In daily life, parents often let their children use headphones. However, adults and children have different levels of acceptance of sound. Children have a lower tolerance for volume than adults. When the volume exceeds a certain value, it will cause irreversible damage to children's hearing. After using headphones, parents often forget to turn down the volume and give them to children directly, which causes harm to the children. Summary of the invention

[0004] The purpose of the present invention is to address the above-mentioned deficiencies in the prior art and to provide a dual-magnetic noise reduction headset and a control method thereof, which can adjust the volume of the headset according to the size of the user's head.

[0005] The purpose of the present invention is achieved through the following technical solutions: a dual-magnetic noise reduction headset, comprising a headset bracket; telescopic frames are provided at both ends of the headset bracket; the telescopic frame comprises a telescopic part and a fixed part; the telescopic part is telescopically arranged at the end of the headset bracket;

[0006] One end of the fixing part is provided with a push rod for abutting against the earphone bracket; the other end of the fixing part is provided with a body;

[0007] The body is provided with a first diaphragm; a receiving cavity is formed between the first diaphragm and the body; a driving unit is provided in the receiving cavity; a lifting bracket is provided for lifting and lowering activities in the receiving cavity; a permanent magnet is provided on the top of the lifting bracket; a second diaphragm is provided at the bottom of the first diaphragm; a magnetorheological fluid is provided between the first diaphragm and the second diaphragm;

[0008] A transmission mechanism is arranged between the push rod and the lifting bracket.

[0009] The present invention is further configured such that the driving unit comprises a first magnetic yoke disposed in the accommodating cavity, a magnetic ring disposed on the top of the first magnetic yoke, and a voice coil disposed at the bottom of the middle of the first diaphragm; an active cavity is disposed in the magnetic ring; the voice coil is movably disposed between the active cavity and the accommodating cavity; the second diaphragm is disposed at the bottom of the edge of the first diaphragm;

[0010] The second diaphragm is arranged on the top of the permanent magnet.

[0011] The present invention is further configured that the fixing portion is provided with a mounting cavity; the push rod is movably arranged in the mounting cavity; the body is rotatably arranged in the mounting cavity;

[0012] The transmission mechanism comprises a horizontal bracket movably arranged in the accommodating cavity; one end of the horizontal bracket protrudes out of the body and is provided with a gasket; the gasket is movably arranged in the installation cavity; the gasket abuts against the push rod;

[0013] The transmission mechanism also includes a driving frame connected with the lifting bracket; the driving frame is provided with an inclined groove; the horizontal bracket is provided with a latch; and the latch is movably arranged in the inclined groove.

[0014] The present invention is further configured such that the lifting bracket is in a ring shape; the permanent magnet is in a ring shape; a protrusion is provided at the edge of the first diaphragm; the second diaphragm is provided at the bottom of the protrusion; a storage cavity for placing magnetorheological fluid is formed between the second diaphragm and the bottom of the protrusion;

[0015] There are multiple second diaphragms; the multiple second diaphragms are arranged around the edge of the first diaphragm at equal angles.

[0016] The present invention is further configured such that a limiting column is provided at the bottom of the accommodating cavity; a reset column is provided at the bottom of the horizontal bracket; and a first reset spring is provided between the reset column and the limiting column;

[0017] There are two drive racks; the two drive racks are symmetrically arranged on both sides of the accommodating cavity.

[0018] The present invention is further configured such that the voice coil includes an annular frame arranged at the bottom of the middle portion of the first diaphragm and an annular coil arranged on the inner wall of the annular frame;

[0019] A boss is provided in the middle of the first magnetic yoke extending upward; the annular coil is arranged outside the boss for lifting and lowering movement; and a dust cover is provided on the top of the middle of the first diaphragm.

[0020] The present invention is further configured such that the bottom of the accommodating cavity is recessed downward to form a pit; a cylindrical portion is provided at the bottom of the boss; an annular movable groove is formed between the four sides of the cylindrical portion and the boss; a second magnetic yoke is provided in the pit for lifting and lowering movement; an annular magnetic yoke portion is provided on the outer periphery of the second magnetic yoke; the annular magnetic yoke portion is in contact with the inner wall of the annular movable groove; and the annular magnetic yoke portion is provided between the pit and the annular movable groove for lifting and lowering movement.

[0021] The present invention is further configured such that a second return spring is provided between the top of the second magnetic yoke and the cylindrical portion;

[0022] The pit is provided with a push block for horizontal movement; the push block is provided with an inclined surface matched with the bottom of the second magnetic yoke; and the push block is connected with the transmission mechanism.

[0023] The present invention is further configured such that a dust cover is provided on the top of the body; a plurality of through holes are provided through the dust cover; and a sponge cover is provided on the top of the dust cover.

[0024] The present invention is further configured such that a noise reduction wave generator is provided in the main body.

[0025] A control method for dual-magnetic noise reduction headphones, comprising the following steps:

[0026] S1, controlling the position of the telescopic part on the earphone bracket;

[0027] S2. The headphone bracket pushes the push rod to move;

[0028] S3, the push rod drives the lifting bracket to move up and down through the transmission mechanism;

[0029] S4, the lifting bracket drives the permanent magnet to move up and down;

[0030] S5, changing the stiffness of the magnetorheological fluid by means of a permanent magnet;

[0031] S6. The stiffness of the magnetorheological fluid changes, thereby changing the amplitude of the first diaphragm.

[0032] Beneficial effects of the present invention: The present invention adjusts the extension and retraction of the telescopic frame according to the size of the user's head, thereby driving the lifting bracket to drive the permanent magnet to lift and lower, and uses the second permanent magnet to change the stiffness of the magnetorheological fluid, thereby limiting the amplitude of the first diaphragm, controlling the volume output, and preventing excessive volume from damaging the hearing of child users. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The invention is further described using the accompanying drawings, but the embodiments in the accompanying drawings do not constitute any limitation to the invention. A person skilled in the art can obtain other drawings based on the following drawings without creative work.

[0034] Figure 1 It is a schematic diagram of the structure of the present invention;

[0035] Figure 2 is a cross-sectional view of the present invention;

[0036] Figure 3 is a cross-sectional view of the telescopic portion of the present invention when it is retracted;

[0037] Figure 4 yes Figure 3 A partial enlarged view of the A part;

[0038] Figure 5 yes Figure 3 A partial enlarged view of the B area;

[0039] Figure 6 is a cross-sectional view of the telescopic portion of the present invention when extended;

[0040] Figure 7 Book Figure 6 A partial enlarged view of the middle C area;

[0041] Among them: 1. Headphone bracket; 11. Dust cover; 12. Perforation; 13. Sponge cover; 14. Noise reduction wave generator; 21. Telescopic part; 22. Fixing part; 23. Installation cavity; 24. Push rod; 3. Body; 31. Accommodating cavity; 32. Limiting column; 33. Reset column; 34. First reset spring; 35. Concave pit; 4. First diaphragm; 41. Raised part; 42. Dust cover; 51. Second diaphragm; 52. Storage cavity; 53. Permanent magnet; 61. Lifting bracket; 62. Horizontal bracket; 63. Gasket; 64. Driving bracket; 65. Inclined groove; 66. Latch; 71. First yoke; 72. Magnetic ring; 73. Movable cavity; 74. Annular coil; 75. Annular skeleton; 8. Boss; 81. Cylindrical part; 82. Annular movable groove; 9. Second yoke; 91. Annular yoke part; 92. Second reset spring; 93. Push block; 94. Inclined surface. DETAILED DESCRIPTION

[0042] The present invention is further described in conjunction with the following examples.

[0043] Depend on Figures 1 to 7 It can be seen that a dual-magnetic noise reduction headset of this embodiment includes an earphone bracket 1; both ends of the earphone bracket 1 are provided with a telescopic frame; the telescopic frame includes a telescopic portion 21 and a fixed portion 22; the telescopic portion 21 is telescopically arranged at the end of the earphone bracket 1; one end of the fixed portion 22 is provided with a push rod 24 for abutting against the earphone bracket 1; the other end of the fixed portion 22 is provided with a body 3;

[0044] The body 3 is provided with a first diaphragm 4; a receiving cavity 31 is formed between the first diaphragm 4 and the body 3; a driving unit is provided in the receiving cavity 31; a lifting bracket 61 is provided in the receiving cavity 31 for lifting and lowering; a permanent magnet 53 is provided on the top of the lifting bracket 61; a second diaphragm 51 is provided at the bottom of the first diaphragm 4; a magnetorheological fluid is provided between the first diaphragm 4 and the second diaphragm 51;

[0045] A transmission mechanism is provided between the push rod 24 and the lifting bracket 61 .

[0046] Specifically, the dual-magnetic noise-cancelling headphones described in this embodiment have a telescopic cavity provided at the end of the headphone stand 1, so that the telescopic portion 21 of the telescopic frame can be telescopically arranged in the telescopic cavity, thereby being able to change the overall length of the dual-magnetic noise-cancelling headphones and matching users of different ages; wherein the telescopic cavity and the telescopic portion 21 of the telescopic frame have sufficient damping to overcome the effects of the first spring and the second spring.

[0047] When the telescopic part 21 is retracted back into the telescopic cavity at the end of the headphone holder 1, the headphone holder 1 will push the push rod 24 to move. During the pushing and moving process, the lifting bracket 61 is driven to rise through the transmission mechanism, thereby causing the permanent magnet 53 to rise. During the rising process of the permanent magnet 53, the magnetorheological fluid between the first diaphragm 4 and the second diaphragm 51 gradually increases in rigidity under the action of the magnetic field of the permanent magnet 53, thereby limiting the amplitude of the first diaphragm 4, limiting the first diaphragm 4 from vibrating greatly and producing excessive volume, thereby controlling the volume output; for younger children, the smaller the size of the head, the more the telescopic part 21 of the telescopic bracket needs to be retracted to the headphone holder 1, thereby making the lifting bracket 61 closer to the second diaphragm 51, which can more effectively limit the first diaphragm 4 from vibrating greatly and producing excessive volume.

[0048] The dual-magnetic noise reduction earphones of this embodiment have a driving unit including a first magnetic yoke 71 arranged in the accommodating cavity 31, a magnetic ring 72 arranged on the top of the first magnetic yoke 71, and a voice coil arranged at the bottom of the middle of the first diaphragm 4; an active cavity 73 is arranged in the magnetic ring 72; the voice coil is movably arranged between the active cavity 73 and the accommodating cavity 31; the second diaphragm 51 is arranged at the bottom of the edge of the first diaphragm 4; the second diaphragm 51 is arranged on the top of the permanent magnet 53.

[0049] Specifically, through the above arrangement, after the voice coil is energized, the voice coil moves up and down under the action of the magnetic ring 72, thereby driving the first diaphragm 4 to vibrate and generate sound.

[0050] In the dual-magnetic noise reduction earphone of the present embodiment, the fixing part 22 is provided with an installation cavity 23; the push rod 24 is movably provided in the installation cavity 23; the body 3 is rotatably provided in the installation cavity 23; the transmission mechanism includes a horizontal bracket 62 movably provided in the accommodating cavity 31; one end of the horizontal bracket 62 protrudes out of the body 3 and is provided with a gasket 63; the gasket 63 is movably provided in the installation cavity 23; the gasket 63 abuts against the push rod 24; the transmission mechanism also includes a driving frame 64 connected to the lifting bracket 61; the driving frame 64 is provided with an inclined groove 65; the horizontal bracket 62 is provided with a latch 66; the latch 66 is movably provided in the inclined groove 65. In the dual-magnetic noise reduction earphone of the present embodiment, a limiting column 32 is provided at the bottom of the accommodating cavity 31; a reset column 33 is provided at the bottom of the horizontal bracket 62; a first reset spring 34 is provided between the reset column 33 and the limiting column 32; the number of the driving frames 64 is two; the two driving frames 64 are symmetrically provided on both sides of the accommodating cavity 31.

[0051] Specifically, the dual magnetic noise reduction headphones described in this embodiment are used by adults as follows: Figure 3In the state shown, the telescopic frame is extended to the end of the earphone holder 1, and under the action of the first return spring 34, one end of the horizontal bracket 62 protrudes out of the main body 3, and the push rod 24 is pressed by the gasket 63 to move to the end of the mounting cavity 23 close to the earphone holder 1. At this time, the lifting bracket 61 and the permanent magnet 53 are far away from the second diaphragm 51, and the magnetorheological fluid is less affected by the permanent magnet 53, so that the rigidity of the second diaphragm 51 and the first diaphragm 4 is smaller, so that the amplitude of the first diaphragm 4 is larger, so that the dual magnetic noise reduction headphones can produce a louder sound.

[0052] When used by children Figure 6 In the state shown, the telescopic frame is retracted to the end of the headphone holder 1, and the distance between the end of the headphone holder 1 and the fixing portion 22 is reduced. The headphone holder 1 pushes the push rod 24 to move toward the main body 3. The push rod 24 pushes the horizontal holder 62 to move to the right through the gasket 63. During the movement of the horizontal holder 62, the lifting bracket 61 is driven to rise through the latch 66 and the inclined groove 65, thereby shortening the distance between the permanent magnet 53 and the second diaphragm 51. The magnetorheological fluid is affected by the permanent magnet 53 and becomes larger, so that the rigidity of the second diaphragm 51 is increased, thereby making the amplitude of the first diaphragm 4 larger, thereby reducing the sound emitted by the dual magnetic noise reduction headphones.

[0053] In the dual-magnetic noise reduction earphone of this embodiment, the lifting bracket 61 is in a ring shape; the permanent magnet 53 is in a ring shape; a protrusion 41 is provided at the edge of the first diaphragm 4; the second diaphragm 51 is provided at the bottom of the protrusion 41; a storage cavity 52 for placing magnetorheological fluid is formed between the second diaphragm 51 and the bottom of the protrusion 41;

[0054] There are multiple second diaphragms 51 ; the multiple second diaphragms 51 are arranged around the edge of the first diaphragm 4 at equal angles.

[0055] Specifically, by setting the protrusion 41, the deformation of the first diaphragm 4 can be compensated when the amplitude of the first diaphragm 4 is large; secondly, multiple second diaphragms 51 are arranged at equal angles around the edge of the first diaphragm 4, so that the structure between the first diaphragm 4 and the second diaphragm 51 is stable and reliable.

[0056] In the dual-magnetic noise reduction earphone of this embodiment, the voice coil includes an annular frame 75 disposed at the bottom of the middle of the first diaphragm 4 and an annular coil 74 disposed on the inner wall of the annular frame 75; a boss 8 is extended upward from the middle of the first magnetic yoke 71; the annular coil 74 is disposed outside the boss 8 for lifting and lowering; and a dust cover 42 is disposed on the top of the middle of the first diaphragm 4. The boss 8 is provided to facilitate the conduction of magnetism, and the dust cover 42 is provided to minimize the entry of dust into the active cavity 73.

[0057] In the dual-magnetic noise-cancelling earphone of the present embodiment, the bottom of the accommodating cavity 31 is recessed downward to form a pit 35; a cylindrical portion 81 is provided at the bottom of the boss 8; an annular movable groove 82 is formed between the cylindrical portion 81 and the boss 8; a second yoke 9 is provided in the pit 35 for lifting and lowering movement; an annular yoke portion 91 is provided on the outer periphery of the second yoke 9; the annular yoke portion 91 contacts the inner wall of the annular movable groove 82; the annular yoke portion 91 is provided between the pit 35 and the annular movable groove 82 for lifting and lowering movement. In the dual-magnetic noise-cancelling earphone of the present embodiment, a second return spring 92 is provided between the top of the second yoke 9 and the cylindrical portion 81; a push block 93 is provided in the pit 35 for horizontal movement; the push block 93 is provided with an inclined surface 94 that matches the bottom of the second yoke 9; the push block 93 is connected to the transmission mechanism.

[0058] Specifically, the dual magnetic noise reduction headphones described in this embodiment are used by adults as follows: Figure 3 In the state shown, the telescopic frame is extended to the end of the headphone holder 1, and under the action of the first return spring 34, one end of the horizontal bracket 62 protrudes out of the main body 3, and the push rod 24 is pressed by the gasket 63 to move to the end of the mounting cavity 23 close to the headphone holder 1; at the same time, the push block 93 moves to the bottom of the second yoke 9, so that the annular yoke portion 91 is completely set in the annular movable groove 82. At this time, the effective contact area between the first yoke 71 and the second yoke 9 is the largest, so that the dual magnetic noise reduction headphones can make a louder sound.

[0059] When used by children Figure 6 In the state shown, the telescopic frame is retracted to the end of the headphone holder 1, and the distance between the end of the headphone holder 1 and the fixing portion 22 is reduced. The headphone holder 1 pushes the push rod 24 to move in the direction close to the body 3. The push rod 24 pushes the horizontal holder 62 to move to the right through the gasket 63. In the process of the horizontal holder 62 moving to the right, the push rod 24 is driven to move to the right. Under the action of the second return spring 92, the second yoke 9 moves downward, so that part of the annular yoke portion 91 moves out of the annular movable groove 82; since the effective contact area between the first yoke 71 and the second yoke 9 is reduced, that is, the magnetic circuit area is reduced, when the magnetic field that can pass through the magnetic circuit area reaches saturation, the remaining magnetic flux lines cannot pass through the second yoke 9 to reach the middle of the first yoke 71, so that the magnetic field at the position corresponding to the annular coil 74 in the middle of the first yoke 71 is reduced, so as to achieve the effect of adjusting the output intensity of the magnetic field; the weakening of the magnetic field can further reduce the output volume of the earphone, so as to achieve the purpose of controlling the volume output.

[0060] In the dual-magnetic noise reduction earphone of this embodiment, a dust cover 11 is provided on the top of the body 3; a plurality of perforations 12 are provided through the dust cover 11; a sponge cover 13 is provided on the top of the dust cover 11. The dust cover 11 can prevent dust from entering the interior of the body 3, and the sponge cover 13 can enhance the comfort of the user.

[0061] In the dual-magnetic noise reduction earphone of this embodiment, a noise reduction wave generator 14 is provided in the body 3. The above arrangement enables noise reduction through an external electronic switch.

[0062] A control method for a dual-magnetic noise reduction headset in this embodiment includes the following steps:

[0063] S1, controlling the position of the telescopic portion 21 on the earphone holder 1;

[0064] S2, the headphone holder 1 pushes the push rod 24 to move;

[0065] S3, the push rod 24 drives the lifting bracket 61 to move up and down through the transmission mechanism;

[0066] S4, the lifting bracket 61 drives the permanent magnet 53 to move up and down;

[0067] S5, changing the stiffness of the magnetorheological fluid by means of the permanent magnet 53;

[0068] S6, the stiffness of the magnetorheological fluid changes, thereby changing the amplitude of the first diaphragm 4.

[0069] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A dual-magnetic noise reduction headset, characterized in that: It includes an earphone stand; both ends of the earphone stand are provided with telescopic frames; the telescopic frame includes a telescopic part and a fixed part; the telescopic part is telescopically arranged at the end of the earphone stand; One end of the fixing part is provided with a push rod for abutting against the earphone bracket; the other end of the fixing part is provided with a body; The body is provided with a first diaphragm; a receiving cavity is formed between the first diaphragm and the body; a driving unit is provided in the receiving cavity; a lifting bracket is provided for lifting and lowering activities in the receiving cavity; a permanent magnet is provided on the top of the lifting bracket; a second diaphragm is provided at the bottom of the first diaphragm; a magnetorheological fluid is provided between the first diaphragm and the second diaphragm; A transmission mechanism is provided between the push rod and the lifting bracket; The driving unit includes a first magnetic yoke arranged in the accommodating cavity, a magnetic ring arranged on the top of the first magnetic yoke, and a voice coil arranged at the bottom of the middle of the first diaphragm; an active cavity is arranged in the magnetic ring; the voice coil is movably arranged between the active cavity and the accommodating cavity; the second diaphragm is arranged at the bottom of the edge of the first diaphragm; The second diaphragm is arranged on the top of the permanent magnet; The fixed part is provided with an installation cavity; the push rod is movably arranged in the installation cavity; the body is rotatably arranged in the installation cavity; The transmission mechanism comprises a horizontal bracket movably arranged in the accommodating cavity; one end of the horizontal bracket protrudes out of the body and is provided with a gasket; the gasket is movably arranged in the installation cavity; the gasket abuts against the push rod; The transmission mechanism also includes a driving frame connected to the lifting bracket; the driving frame is provided with an inclined slot; the horizontal bracket is provided with a latch; the latch is movably arranged in the inclined slot; A limiting column is provided at the bottom of the accommodating cavity; a reset column is provided at the bottom of the horizontal bracket; a first reset spring is provided between the reset column and the limiting column; There are two drive racks; the two drive racks are symmetrically arranged on both sides of the accommodating cavity.

2. A dual-magnetic noise reduction headset according to claim 1, characterized in that: The lifting bracket is in a ring shape; the permanent magnet is in a ring shape; a convex portion is provided on the edge of the first diaphragm; the second diaphragm is provided at the bottom of the convex portion; a storage cavity for placing magnetorheological fluid is formed between the second diaphragm and the bottom of the convex portion; There are multiple second diaphragms; the multiple second diaphragms are arranged around the edge of the first diaphragm at equal angles.

3. A dual magnetic noise reduction headset according to claim 1, characterized in that: The voice coil comprises an annular frame arranged at the bottom of the middle part of the first diaphragm and an annular coil arranged on the inner wall of the annular frame; A boss is provided in the middle of the first magnetic yoke extending upward; the annular coil is arranged outside the boss for lifting and lowering movement; and a dust cover is provided on the top of the middle of the first diaphragm.

4. A dual-magnetic noise reduction headset according to claim 3, characterized in that: The bottom of the accommodating cavity is recessed to form a pit; a cylindrical portion is provided at the bottom of the boss; an annular movable groove is formed between the cylindrical portion and the boss; a second magnetic yoke is provided in the pit for lifting and lowering movement; an annular magnetic yoke portion is provided on the outer periphery of the second magnetic yoke; the annular magnetic yoke portion contacts the inner wall of the annular movable groove; and the annular magnetic yoke portion is provided between the pit and the annular movable groove for lifting and lowering movement.

5. A dual-magnetic noise reduction headset according to claim 4, characterized in that: A second return spring is provided between the top of the second magnetic yoke and the cylindrical portion; The pit is provided with a push block for horizontal movement; the push block is provided with an inclined surface matched with the bottom of the second magnetic yoke; and the push block is connected with the transmission mechanism.

6. A control method for the dual-magnetic noise reduction earphone according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1, controlling the position of the telescopic part on the earphone bracket; S2. The headphone bracket pushes the push rod to move; S3, the push rod drives the lifting bracket to move up and down through the transmission mechanism; S4, the lifting bracket drives the permanent magnet to move up and down; S5, changing the stiffness of the magnetorheological fluid by means of a permanent magnet; S6. The stiffness of the magnetorheological fluid changes, thereby changing the amplitude of the first diaphragm.

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