earphones

Abstract

To provide an earphone with a simple structure that eliminates the discomfort of pressing on an eardrum and alleviates the easiness of coming off due to the air pressure difference between the inside and outside of an external auditory canal.SOLUTION: An earphone includes a housing, a diaphragm which is provided in the housing and is movable between a first position capable of vibrating and outputting sound and a second position projecting from the first position in a direction of outputting sound, a voice coil that drives the diaphragm with an input signal, and a signal supply unit that supplies a signal to the voice coil such that the diaphragm switches between the first position and the second position.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to earphones. [Background Art]

[0002] A canal-type (earplug-type) earphone is known which is used by providing a cylindrically protruding sound tube portion on a housing that accommodates a speaker unit, inserting an earpiece attached to the sound tube portion into the external auditory canal, and mounting the earphone on the auricle.

[0003] In a canal-type earphone, the earpiece and the inner wall of the external auditory canal are substantially in close contact during use. Therefore, when the earpiece is inserted into the external auditory canal, the internal space of the external auditory canal becomes sealed, the internal air is compressed, and the pressure increases. This causes a problem that the eardrum is compressed, causing a sense of discomfort.

[0004] To solve these problems, there is known a technique in which a housing divided into two parts, a cylinder and a piston, is used, and the position of the hole of the cylinder and the position of the hole of the piston are aligned to reduce the air pressure difference between the inside and outside of the external auditory canal (for example, Patent Document 1). [Prior Art Documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Laying-Open No. 2018-121286 [Summary of the Invention] [Problem to be Solved by the Invention]

[0006] However, implementing the above technique in a small earphone whose earpiece is inserted into the ear requires a complicated structure, and advanced processing technology is required for implementation.

[0007] The present invention has been made in view of the above, and aims to provide an earphone that eliminates the discomfort of pressure on the eardrum, reduces the tendency to fall out due to the pressure difference inside and outside the ear canal, and has a simple structure. [Means for solving the problem]

[0008] The earphones according to this disclosure include a housing, a diaphragm provided within the housing and movable between a first position capable of vibrating and outputting sound, and a second position protruding from the first position in the direction of outputting sound, a voice coil that drives the diaphragm by an input signal, and a signal supply unit that supplies the signal to the voice coil so that the diaphragm moves by switching between the first position and the second position.

[0009] The earphones according to this disclosure include a housing, a diaphragm provided inside the housing and which outputs sound by vibrating, a voice coil that drives the diaphragm in response to an input signal, and a switch provided outside the housing, wherein the diaphragm is movable between a first position and a second position which protrudes from the first position in the direction of sound output, and when the diaphragm is in the first position, when the signal is input to the voice coil, the diaphragm vibrates and outputs sound, when the switch is operated the diaphragm protrudes from the first position to the second position, and when the switch is not operated the diaphragm is in the first position. [Effects of the Invention]

[0010] According to this disclosure, the simple structure eliminates the discomfort caused by pressure on the eardrum and reduces the likelihood of the earpiece falling out due to the pressure difference inside and outside the ear canal. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a longitudinal cross-sectional view illustrating the structure of an earphone according to an embodiment of the present invention. [Figure 2]Figure 2 shows an example of a signal amplification circuit. [Figure 3] Figure 3 is a longitudinal cross-sectional view illustrating the structure of the earphone. [Figure 4] Figure 4 is a waveform diagram showing an example of the operation of the signal amplification circuit shown in Figure 2. [Figure 5] Figure 5 is a waveform diagram showing an example of the operation of the signal amplification circuit shown in Figure 2. [Figure 6] Figure 6 is a waveform diagram showing an example of the operation of the signal amplification circuit shown in Figure 2. [Figure 7] Figure 7 is a longitudinal cross-sectional view illustrating the procedure for putting on earphones. [Figure 8] Figure 8 is a longitudinal cross-sectional view illustrating the procedure for putting on earphones. [Figure 9] Figure 9 is a longitudinal cross-sectional view illustrating the procedure for putting on earphones. [Figure 10] Figure 10 shows a first modified example of the signal amplification circuit. [Figure 11] Figure 11 shows a second modified example of the signal amplification circuit. [Figure 12] Figure 12 is a longitudinal cross-sectional view showing an example of an earphone configuration using the signal amplification circuit shown in Figure 11. [Figure 13] Figure 13 shows a third modified example of the signal amplification circuit. [Figure 14] Figure 14 shows an example of a signal amplification circuit according to another embodiment. [Figure 15] Figure 15 shows an example of a signal output from the audio playback unit. [Figure 16] Figure 16 shows an example of a signal input to a voice coil. [Modes for carrying out the invention]

[0012] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description of each embodiment, the same or equivalent components as those in other embodiments are denoted by the same reference numerals, and the description thereof will be simplified or omitted. The present invention is not limited by the respective embodiments. In addition, the constituent elements of each embodiment include those that can be easily replaced by a person skilled in the art, or those that are substantially identical. The configurations described below can be combined as appropriate. In addition, omissions, substitutions, or changes in the configuration can be made without departing from the gist of the invention.

[0013] [Configuration] Fig. 1 is a longitudinal cross-sectional view for explaining the structure of an earphone 51 according to an embodiment of the present invention. Hereinafter, for convenience of description, the front-rear direction of the earphone 51 is defined by the reciprocating arrow shown in Fig. 1. The front side is the ear (head) side on which the earphone 51 is worn during use.

[0014] The earphone 51 includes a main body portion 1 that accommodates a speaker unit 3 therein. The main body portion 1 has a cylindrical sound tube portion 4a protruding forward. An earpiece 2 is attached to the sound tube portion 4a. The earpiece 2 is detachably attached to the sound tube portion 4a. The earphone 51 is a so-called canal-type (earplug-type) earphone that is used by inserting the earpiece 2 into the external auditory canal and attaching the main body portion 1 to the auricle. In each drawing, the cord and the bushing drawn out from the speaker unit 3 to the outside are not illustrated. The earphone 51 may be cordless, and may receive audio signals via short-range wireless communication or the like.

[0015] The main body 1 has a front housing 4 and a rear housing 5 that are combined front and rear. The combined front housing 4 and rear housing 5 constitute the housing 6. In the housing 6, the front housing 4 and the rear housing 5 are each formed in a bottomed pot shape with axis CL1 as the center. The sound tube portion 4a is formed to protrude forward of axis CL1 in the front housing 4. In the example shown in Figure 1, the axis of the sound tube portion 4a is aligned with axis CL. This structure is not limited to this, and the axis of the sound tube portion 4a does not have to be aligned with axis CL. That is, the axes do not coincide, and the axis of the sound tube portion 4a is inclined with respect to the axis CL of the housing 6. If the axis of the sound tube portion 4a is inclined with respect to axis CL at a predetermined angle, the fit of the earpiece 2 in the ear canal may be improved.

[0016] The front housing 4 and rear housing 5 are formed of, for example, resin. The resin is, for example, PC (polycarbonate). The earpiece 2 is formed of a flexible material such as rubber. The earpiece 2 is formed of, for example, silicone rubber.

[0017] A baffle 7 is installed inside the housing 6. In this example, the baffle 7 is an annular shape centered on the axis CL1. The speaker unit 3 is fitted inside the annular shape of the baffle 7. In this way, the baffle 7 holds the side surface 3j of the speaker unit 3. The speaker unit 3 and the baffle 7 that supports it constitute the baffle body B2. Thus, the earphone 51 has a baffle 7 that supports the speaker unit 3 and divides the internal space of the housing 6 into front and back sections. The baffle 7 is made of, for example, resin. The resin is, for example, PC (polycarbonate). Note that the baffle 7 may be an annular shape centered on a point other than the axis CL1. Also, the baffle 7 may be a shape other than an annular shape, for example, an elliptical annular shape.

[0018] A signal amplification circuit C1 is provided inside the housing 6. In this example, the circuit board of the signal amplification circuit C1 is fixed to the rear housing 5 of the housing 6. The signal amplification circuit C1 is a signal supply unit that supplies a signal to the voice coil 3f. The signal amplification circuit C1 will be described later.

[0019] The external surface of the housing 6 is provided with a switch operation section 8, which will be described later. The operation section 8 is positioned so that the wearer naturally touches it when inserting the earphones.

[0020] The speaker unit 3 is an electroacoustic transducer in which an audio signal is input from an external source via a cord (not shown), causing the diaphragm 3a to vibrate in the front-to-back direction and outputting sound mainly from the sound emission surface 3k to one side (the front side in Figure 1).

[0021] More specifically, the speaker unit 3 has a fixing part that includes an annular frame 3b, a bottomed pot-shaped yoke 3c fixed to the inside of the frame 3b, a cylindrical magnet 3d fixed to the bottom wall of the yoke 3c, and a disc-shaped top plate 3e fixed to the front end of the magnet 3d.

[0022] Furthermore, the speaker unit 3 includes a cylindrical voice coil 3f positioned outside the top plate 3e and magnet 3d with axis CL1 as its central axis, and a diaphragm 3a to which the front end of the voice coil 3f is connected in the radial middle section, with its outer edge fixed to the frame 3b as an edge 3a1, and capable of reciprocating in the direction of axis CL1. Figure 1 shows the state in which the diaphragm 3a is in a first position. The first position is the position of the diaphragm 3a when no signal is applied to the voice coil 3f. Let L1 be the amount of protrusion of the diaphragm 3a in the direction of arrow Y1 in the first position.

[0023] The manufacturing process for the earphone 51 is as follows: The pre-formed baffle body B2 is fixed to the front housing 4. Specifically, an annular stepped portion 4b is formed on the rear inner surface of the front housing 4, into which the peripheral edge of the baffle 7 in the baffle body B2 engages. The base portion 7a of the baffle 7 is engaged with this stepped portion 4b from the rear and fixed by adhesive or welding. Furthermore, the front end of the rear housing 5 is butted against the rear end of the front housing 4 in a recessed-protrusion fitting, and the base portion 7a of the baffle 7 is sandwiched between them and integrated by adhesive or welding.

[0024] Furthermore, the space Va immediately behind the diaphragm 3a, which is the diaphragm of the speaker unit 3, is connected to the rear space Vg via a through-hole 3g. An acoustic filter 28a may be attached to cover the opening of the through-hole 3g in a way that allows for ventilation.

[0025] The baffle body B2, which includes the baffle 7 and the speaker unit 3, substantially divides the interior of the housing 6 into a front space Vf of the front air chamber and a rear space Vg of the rear air chamber of the baffle 7.

[0026] [Example of a signal amplification circuit configuration] Figure 2 shows an example of a signal amplification circuit C1. As shown in Figure 2, the signal amplification circuit C1 includes an audio playback unit 11, an operational amplifier A1, capacitors 12 and 13, resistors R11 and R12, and a switch SW1.

[0027] The audio playback unit 11 plays back the received audio. The audio playback unit 11 is, for example, a D / A converter, a vocoder, or a codec.

[0028] Operational amplifier A1 has an inverting input terminal (-), a non-inverting input terminal (+), and an output terminal. The inverting input terminal (-) of operational amplifier A1 is connected to one end of resistor R11 and one end of resistor R12. The other end of resistor R11 is connected to the output terminal of operational amplifier A1. As a result, the output of operational amplifier A1 is fed back to the inverting input terminal of operational amplifier A1. The non-inverting input terminal (+) of operational amplifier A1 is connected to the power supply potential 14. Therefore, operational amplifier A1, resistor R11, and resistor R12 act as an inverting amplifier AMP1 that inverts and amplifies the signal applied to the other end of resistor R12.

[0029] The other end of the resistor R12 is connected to one end of the capacitor 12. The other end of the capacitor 12 is connected to the output of the audio playback unit 11. The capacitor 12 removes the DC component contained in the audio signal output from the audio playback unit 11.

[0030] One end of capacitor 13 is connected to the output of operational amplifier A1. The other end of capacitor 13 is connected to one end of voice coil 3f. Capacitor 13 removes the DC component contained in the inverting amplified signal output from operational amplifier A1. The inverting amplified signal from which the DC component has been removed is output from signal amplification circuit C1. The output of signal amplification circuit C1 is connected to one end of voice coil 3f. The other end of voice coil 3f is connected to the reference potential 15. The signal output from signal amplification circuit C1 corresponds to signals S2 and S3, which will be described later.

[0031] Here, one end of the capacitor 13 is connected to the first terminal T11 of the switch SW1. The other end of the capacitor 13 is connected to the second terminal T12 of the switch SW1. In other words, the switch SW1 is connected in parallel with the capacitor 13. The switch SW1 is a momentary switch that is ON only while the operation unit 8 is being operated.

[0032] When the operation unit 8, as explained with reference to Figure 1, is operated, the switch SW1 changes from the off state to the on state. When the switch SW1 is in the off state, the first terminal T11 and the second terminal T12 are not connected, and the capacitor 13 is not bypassed. When the switch SW1 is in the on state, the first terminal T11 and the second terminal T12 are electrically connected, and the capacitor 13 is bypassed. Specifically, while the wearer's fingers or other body parts are touching the operation unit 8, the switch SW1 is in the on state, and the capacitor 13 is bypassed. When the fingers or other body parts that were touching the operation unit 8 are removed, the switch SW1 returns to the off state, and the capacitor 13 is not bypassed.

[0033] [Operation] When switch SW1 is in the off position, the first terminal T11 and the second terminal T12 are not connected, and capacitor 13 is not bypassed. As a result, the DC component of the inverting amplification signal output from op-amp A1 is removed, and only the AC component of the inverting amplification signal is input to voice coil 3f. Voice coil 3f generates a force based on the input signal. The resulting electromagnetic force causes diaphragm 3a to vibrate, generating sound.

[0034] When switch SW1 is ON, the first terminal T11 and the second terminal T12 are electrically connected. As a result, when switch SW1 is ON, capacitor 13 is bypassed, and the inverting amplification signal output from op-amp A1 is directly input to voice coil 3f. In other words, the DC component is not cut by capacitor 13. Therefore, the inverting amplification signal input to voice coil 3f contains a DC component. Due to the force generated by voice coil 3f based on the DC voltage of the inverting amplification signal, the diaphragm 3a protrudes significantly in the direction of arrow Y1 in Figure 1.

[0035] Figure 3 is a longitudinal cross-sectional view illustrating the structure of the earphone 51. Figure 3 shows the state in which the diaphragm 3a protrudes in the direction of arrow Y1 in Figure 1. As shown in Figure 3, the position in which the diaphragm 3a protrudes is called the second position. In the second position, the amount of protrusion of the diaphragm 3a in the direction of arrow Y1 shown in Figure 3 is L2. The amount of protrusion L2 is greater than the amount of protrusion L1 in the first position.

[0036] [Example of a signal waveform] Figures 4, 5, and 6 are waveform diagrams showing examples of operation of the signal amplifier circuit C1 shown in Figure 2. In Figures 4, 5, and 6, the horizontal axis represents time and the vertical axis represents voltage. In Figures 4, 5, and 6, the dashed line represents the midpoint voltage P.

[0037] Figure 4 shows an example of a signal S1 output from the audio playback unit 11 with the DC component removed. The signal S1 shown in Figure 4 has an amplitude centered on the midpoint voltage P.

[0038] Figure 5 shows an example of signal S2 in Figure 2. Figure 5 shows an example of signal S2 when switch SW1 in Figure 2 is in the off state. Referring to Figure 5, signal S2 is an inverted and amplified signal of signal S1 shown in Figure 4. That is, signal S2 is a signal that is the inverted and amplified version of signal S1. When signal S2 is applied to the voice coil 3f, the diaphragm 3a vibrates and sound is generated.

[0039] Figure 6 shows an example of signal S3 when switch SW1 in Figure 2 is in the ON state. Referring to Figure 6, signal S3 is a constant voltage that is larger than the midpoint voltage P. Therefore, as explained with reference to Figure 3, the amount of protrusion of the diaphragm 3a in the direction of arrow Y1 is larger than in the case shown in Figure 1.

[0040] [Installation Instructions] Next, the procedure for inserting the earphone 51 will be described. Figures 7, 8, and 9 are longitudinal cross-sectional views illustrating the procedure for inserting the earphone 51. Figure 7 shows the state before inserting the earphone 51 into the wearer's ear canal 62. Figure 8 shows the state during insertion of the earphone 51 into the ear canal 62. Figure 9 shows the state after insertion of the earphone 51 into the ear canal 62 is complete. In these figures, the eardrum 63 is located at the back (internal) side of the ear canal 62. The auricle 61 is located at the front (outer) side of the ear canal 62.

[0041] When the diaphragm 3a is in the first position, if a signal is input to the voice coil, the diaphragm 3a is driven. The vibration of the diaphragm 3a causes the earphone 51 to output sound.

[0042] Before inserting the earpiece 2 into the ear canal 62, if the wearer's fingers or other objects touch the control unit 8, the diaphragm 3a will protrude from the first position to the second position, in this example toward the inside of the ear canal 62 (direction of arrow Y1), as shown in Figure 7. The protrusion of the diaphragm 3a from the first position to the second position pushes the air inside the sound tube 4a in the direction of arrow Y1. Therefore, it can also be said that in the second position, the diaphragm 3a is protruding in the direction that pushes the air inside the sound tube 4a. The second position is the position in which the diaphragm 3a is protruding from the first position toward the direction that outputs sound. In other words, when the control unit 8 is operated during ear placement, the diaphragm 3a moves to the second position.

[0043] If the wearer's fingers or other body parts touch the control unit 8 while inserting the earpiece 2 into the ear canal 62, the diaphragm 3a will remain protruding from the first position to the second position, as shown in Figure 8. As shown in Figure 8, the earpiece 2 deforms upon contact with the inner wall of the ear canal 62. As a result, the earpiece 2 becomes tightly fitted against the inner wall of the ear canal 62.

[0044] When the earpiece 2 is fully inserted into the ear canal 62, and contact with the operating part 8, such as the wearer's finger, is released, the protrusion to the second position is released, as shown in Figure 9. As a result, the diaphragm 3a returns to the first position. In other words, once the earpiece is fully inserted into the ear and the operating part 8 is not operated, the diaphragm 3a moves to the first position. This allows the air pressure inside the ear canal 62 to be lowered while the earpiece 2 of the earphone 51 seals the ear canal 62. By lowering the air pressure inside the ear canal 62, the pressure difference between the inside and outside of the ear canal 62 can be eliminated or reduced. This prevents discomfort caused by pressure on the eardrum 63. Furthermore, by eliminating or reducing the pressure difference between the inside and outside of the ear canal 62, the earpiece 2 of the earphone 51 can be prevented from falling out of the ear canal 62.

[0045] When the earpiece 2 is inserted into the ear canal 62 and the diaphragm 3a is in the first position, a signal is input to the voice coil, causing the diaphragm 3a to be driven. The vibration of the diaphragm 3a causes the earphone 51 to output sound.

[0046] When removing the earphone 51 from the ear canal 62, if the wearer's fingers or other body parts touch the operating part 8, the diaphragm 3a may be made to protrude from the first position to the second position, as shown in Figure 8. This prevents a decrease in air pressure inside the ear canal 62, which could cause discomfort.

[0047] The position of the operating part 8 does not have to be the position described with reference to Figures 1, 3, and 7 to 9. However, it is preferable that the position of the operating part 8 be a position that the wearer unconsciously touches with their fingers when inserting the earphone 51 into the ear canal 62. If it is in such a position, it can be extended from the first position to the second position without any special operation and without burdening the wearer.

[0048] The above describes the case where the signal amplification circuit is provided inside the housing of the earphone 51, but the signal amplification circuit may also be provided in a housing separate from the earphone 51.

[0049] The above describes the case where the operating unit 8 is provided on the outer surface of the housing of the earphone 51, but the operating unit 8 may also be provided on a housing separate from the earphone 51.

[0050] The above describes the case where the audio playback unit 11 is located inside the housing of the earphone 51, but the audio playback unit 11 may be located in a separate housing from the earphone 51. For example, the audio playback unit 11 may be located in a handheld transceiver or a music player.

[0051] [First modified example of a signal amplification circuit] [composition] Figure 10 shows a first modified example of the signal amplification circuit. The signal amplification circuit C2a shown in Figure 10 employs a BTL (Bridge Tied Load, or Bridged Transformer Less) connection with respect to the voice coil 3f. The signal amplification circuit C2a is a signal supply unit that supplies a signal to the voice coil 3f.

[0052] The signal amplification circuit C2a includes an inverting amplifier AMP1 and an inverting amplifier AMP2 connected to its output side. The configuration of the inverting amplifier AMP1 is as described with reference to Figure 2. However, the inverting input terminal (-) of operational amplifier A1 is connected to the reference potential 15 via switch SW2. Switch SW2 includes a first terminal T21 connected to the inverting input terminal (-) of operational amplifier A1 and a second terminal T22 connected to the reference potential T15. Switch SW2 is turned on or off by operating the control unit 8 (see Figure 1).

[0053] The inverting amplifier AMP2 includes operational amplifier A2, resistors R21 and R22, and its output is connected to the inverting input terminal (-) of operational amplifier A2 via resistor R21. This feeds the output of operational amplifier A2 back to its inverting input terminal. The non-inverting input terminal (+) of operational amplifier A2 is connected to the power supply potential 16. Therefore, operational amplifier A2, resistors R21 and R22 operate as an inverting amplifier AMP2, amplifying the applied signal.

[0054] The signal S4a, which is the output of the inverting amplifier AMP2, is a signal obtained by inverting and amplifying the signal S1, and then inverting and amplifying that signal. Signal S4a is input to the voice coil 3f. Similarly, the signal S4b output from the inverting amplifier AMP1 is also input to the voice coil 3f. In the signal amplification circuit C1 described with reference to Figure 2, the amplification circuit is connected in a single-ended push-pull (SEPP) configuration, and the DC cut capacitor at the output is bypassed by a switch to input a DC signal to the voice coil 3f. In contrast, the signal amplification circuit C2a shown in Figure 10 inputs the differential signals S4a and S4b to the voice coil 3f.

[0055] [Operation] When inserting the earphone 51, which employs the signal amplification circuit C2a shown in Figure 10, into the ear canal 62, the switch SW2 changes from the off state to the on state when the wearer's finger or other object touches the operating part 8. As a result, the inverting input terminal (-) of the operational amplifier A1 is connected to the reference potential. This sets the reference potential to the intermediate potential. Consequently, as explained with reference to Figure 6, a constant voltage larger than the midpoint voltage P is input to the voice coil 3f, and the amount of protrusion of the diaphragm 3a in the direction of arrow Y1 becomes larger than in the case shown in Figure 1.

[0056] After insertion into the ear canal 62, when the finger or other object touching the control part 8 is removed, the switch SW2 turns off. This returns the voice coil 3f to its normal protrusion. When signals S4a and S4b are input to the voice coil 3f, sound is reproduced by the vibration of the diaphragm 3a.

[0057] Furthermore, since the signal amplification circuit C2a employs a BTL connection for the voice coil 3f, the current value driving the voice coil 3f is twice that of the case in Figure 2. Therefore, when the power source for the earphone 51 is a battery, sufficient sound output can be obtained even when using a battery with a low output voltage.

[0058] [Second variation of the signal amplification circuit] [composition] Figure 11 shows a second modified example of the signal amplification circuit. The signal amplification circuit C2b shown in Figure 11 employs a BTL (Bridge Tied Load, or Bridged Transformer Less) connection for the voice coil 3f, similar to the case in Figure 10. The signal amplification circuit C2b is the signal supply unit that supplies a signal to the voice coil 3f.

[0059] The signal amplification circuit C2b shown in Figure 11 is the same as the signal amplification circuit C2a shown in Figure 10, but with the addition of a variable resistor element VR1 connected between the switch SW2 and the reference potential.

[0060] Figure 12 is a longitudinal cross-sectional view showing an example configuration of the earphone 52 when the signal amplification circuit C2b shown in Figure 11 is used. The variable resistor element VR1 shown in Figure 12 is located outside the signal amplification circuit C2b, but is part of the signal amplification circuit C2b. The resistance value can be adjusted by operating the knob KN of the variable resistor element VR1. For example, the resistance value can be adjusted by rotating the knob KN clockwise or counterclockwise around the axis CL1. The DC voltage value applied to the voice coil 3f when the switch SW2 is turned ON can be adjusted by the resistance value adjusted by the variable resistor element VR1.

[0061] [Operation] When inserting the earphone 52, which employs the signal amplification circuit C2b shown in Figure 11, into the ear canal 62, the switch SW2 changes from the off state to the on state when the wearer's finger or other object touches the operating part 8. This connects the inverting input terminal (-) of the operational amplifier A1 to the reference potential. As a result, a DC voltage corresponding to the resistance value adjusted by the variable resistor element VR1 is applied to the voice coil 3f.

[0062] Here, by setting the resistance value of the variable resistor element VR1 to a sufficiently small value, when the switch SW2 is turned on, a constant voltage larger than the midpoint voltage P is applied to the voice coil 3f, and the amount of protrusion of the diaphragm 3a in the direction of arrow Y1 becomes larger than in the case shown in Figure 1. By appropriately setting the resistance value of the variable resistor element VR1, the amount of protrusion of the diaphragm 3a in the direction of arrow Y1 can be set to an appropriate value.

[0063] After insertion into the ear canal 62, when the finger or other object touching the control part 8 is removed, the switch SW2 turns off. This returns the voice coil 3f to its normal protrusion. When signals S4a and S4b are input to the voice coil 3f, sound is reproduced by the vibration of the diaphragm 3a.

[0064] Furthermore, since the signal amplification circuit C2b employs a BTL connection for the voice coil 3f, the current value driving the voice coil 3f is twice that of the case in Figure 2. Therefore, even when the power supply for the earphone 52 is a battery with a low output voltage, sufficient sound output can be obtained.

[0065] [Third variation of the signal amplification circuit] [composition] Figure 13 shows a third modified example of the signal amplification circuit. As shown in Figure 13, the signal amplification circuit C2c includes an audio playback unit 11, an operational amplifier A1, capacitors 12 and 13, resistors R11 and R12, a bypass switch 17, a bypass switch control unit 18, and a switch SW1c. The signal amplification circuit C2c is a signal supply unit that supplies a signal to the voice coil 3f. The signal amplification circuit C2c differs from the signal amplification circuit C1 in that a bypass switch 17, a bypass switch control unit 18, and a switch SW1c are provided instead of the switch SW1. In Figure 13, the bypass switch 17 is composed of, for example, two transistors and one resistor, but is not limited to this configuration and may be configured in other ways. The other audio playback unit 11, operational amplifier A1, capacitors 12 and 13, and resistors R11 and R12 are the same as those in the signal amplification circuit C1 of the above embodiment.

[0066] When the operation on the operation unit 8 described above is performed, the switch SW1c changes from the off state to the on state. When the switch SW1c is in the off state, the bypass switch control unit 18 controls the bypass switch 17 so that the capacitor 13 is not bypassed. When the switch SW1c is in the on state, the bypass switch control unit 18 controls the bypass switch 17 so that the capacitor 13 is bypassed. For example, while the wearer's finger or other object is touching the operation unit 8, the switch SW1c is in the on state and the capacitor 13 is bypassed. When the finger or other object that was touching the operation unit 8 leaves the operation unit 8, the switch SW1c is in the off state and the capacitor 13 is not bypassed.

[0067] [Operation] When switch SW1c is in the off state, the bypass switch control unit 18 controls the capacitor 13 so that it is not bypassed. As a result, the DC component of the inverting amplifier signal output from op-amp A1 is removed, and only the AC component of the inverting amplifier signal is input to the voice coil 3f. The voice coil 3f generates a force based on the input signal. The electromagnetic force generated by this causes the diaphragm 3a to vibrate, producing sound.

[0068] When switch SW1c is ON, the bypass switch control unit 18 bypasses capacitor 13, and the inverting amplification signal output from op-amp A1 is directly input to voice coil 3f. In other words, the DC component is not cut off by capacitor 13. Therefore, the inverting amplification signal input to voice coil 3f contains a DC component. The force generated by voice coil 3f based on the DC voltage of the inverting amplification signal causes diaphragm 3a to protrude significantly in the direction of arrow Y1 in Figure 1.

[0069] Furthermore, in the signal amplification circuit C2c, the bypass switch control unit 18 controls the bypass switch 17 to switch between the bypassed and unbypassed states of the capacitor 13, thereby suppressing the generation of popping noises during this switching. This reduces any discomfort the user may feel.

[0070] [Other embodiments of signal amplification circuits] [composition] Figure 14 shows an example of a signal amplification circuit according to another embodiment. As shown in Figure 14, the signal amplification circuit C3 employs a BTL (Bridge Tied Load, or Bridged Transformer Less) connection with respect to the voice coil 3f. The signal amplification circuit C3 is a signal supply unit that supplies a signal to the voice coil 3f.

[0071] The signal amplification circuit C3, like the signal amplification circuit C2a shown in Figure 10, includes an inverting amplifier AMP1 and an inverting amplifier AMP2 connected to its output side. The configurations of the inverting amplifiers AMP1 and AMP2 are as described with reference to Figure 10. The signal amplification circuit C3 differs from the signal amplification circuit C2a in that it does not have a capacitor 12, and instead of switch SW2, it has a switch SW3 and a midpoint voltage control unit 19.

[0072] When the operation described above is performed on the operation unit 8, the switch SW3 changes from the off state to the on state. The midpoint voltage control unit 19 controls the midpoint voltage of the signal S4 output from the audio playback unit 11 according to the off and on states of the switch SW3.

[0073] [Operation] When inserting the earphone 51, which employs the signal amplification circuit C3 shown in Figure 14, into the ear canal 62, the switch SW3 changes from the off state to the on state when the wearer's finger or other object touches the control unit 8.

[0074] Figure 15 shows an example of a signal S4 output from the audio playback unit 11. As shown in Figure 15, when the switch SW3 is in the off state, the midpoint voltage control unit 19 controls the midpoint voltage of the signal S4 output from the audio playback unit 11 to be the first midpoint voltage P1. The first midpoint voltage P1 is set as a value to keep the diaphragm 3a in a state where it can vibrate at the first position. When the diaphragm 3a is vibrated to output sound, the audio playback unit 11 outputs a signal whose voltage value fluctuates around the first midpoint voltage P1 to correspond to the vibration. The following explanation will use the case where the diaphragm 3a is not vibrated as an example. When the diaphragm 3a is kept in a state of standby without vibrating at the first position, the audio playback unit 11 outputs a signal S4 with the voltage value of the first midpoint voltage P1 as the output value.

[0075] When the switch SW3 is ON, the midpoint voltage control unit 19 controls the midpoint voltage of the signal S4 to a second midpoint voltage P2 that is different from the first midpoint voltage P2. The second midpoint voltage P2 is set as a value to position the diaphragm 3a at a second position. As in the above embodiment, the second position is a position that protrudes from the first position in the direction of sound output. By changing the midpoint voltage of the signal S4, the voltage value of the signal S4 output from the sound playback unit 11 changes from the first midpoint voltage P1 to the second midpoint voltage P2.

[0076] The example in Figure 15 shows the case where switch SW3 switches from the off state to the on state at time t. In the case shown in Figure 15, the midpoint voltage control unit 19 controls the signal S4 so that its midpoint voltage is the first midpoint voltage P1 until time t, and then controls the signal S4 so that its midpoint voltage switches from the first midpoint voltage P1 to the second midpoint voltage P2 at time t. As a result of this control, the voltage value of the signal S4 output from the audio output unit 11 changes curvilinearly from the first midpoint voltage P1 to the second midpoint voltage P2.

[0077] Figure 16 shows an example of a signal S5 input to the voice coil 3f. As shown in Figure 16, the voltage value of signal S5 changes according to the voltage value of signal S4 output from the audio playback unit 11. That is, if the voltage value of signal S4 is the first midpoint voltage P1, the voltage value of signal S5 input to the voice coil 3f becomes the first voltage V1 corresponding to the first midpoint voltage P1. When the first voltage V1 is input to the voice coil 3f, the diaphragm 3a is positioned in the first position.

[0078] When the voltage value of signal S4 is the second midpoint voltage P2, the voltage value of signal S5 input to voice coil 3f becomes the second voltage V2, which corresponds to the second midpoint voltage P2. In the signal amplification circuit C3, the signal is supplied to voice coil 3f via inverting amplifiers AMP1 and AMP2, so the second voltage V2 is greater than the first voltage V1. When the second voltage V2 is input to voice coil 3f, the diaphragm 3a is positioned in the second position.

[0079] Furthermore, when the voltage value of signal S4 changes curvilinearly from the first midpoint voltage P1 to the second midpoint voltage P2, the voltage value of signal S5 changes curvilinearly from the first voltage V1 to the second voltage V2 to correspond to the change in the voltage value of signal S4. Because the voltage value of signal S5 changes smoothly in this way, the discomfort felt by the user can be mitigated.

[0080] In the above example, the midpoint voltage control unit 19 can set the value of the second midpoint voltage according to the distance between the first position and the second position. For example, as shown by the dashed line in Figure 15, the midpoint voltage control unit 19 can set the value of the second midpoint voltage to a voltage value P3 that is greater than the voltage value P2 described above. In this case, the amount of variation from the first midpoint voltage P1 becomes smaller. As a result, as shown by the dashed line in Figure 16, the voltage value of the second voltage of the signal S5 input to the voice coil 3f becomes V3, which is smaller than V2. Therefore, the distance between the first position and the second position, i.e., the travel distance of the diaphragm 3a, becomes smaller when the voltage value of the second midpoint voltage is P3 compared to when the voltage value of the second midpoint voltage is P2. In this way, the amount of change in the midpoint voltage can be appropriately set according to the distance between the first position and the second position by controlling the midpoint voltage control unit 19, so that the optimal air pressure according to the user can be easily and appropriately controlled without using, for example, a variable resistor.

[0081] The earphones 51 and 52 described above include a housing 2, a diaphragm 3a provided inside the housing 2 and movable between a first position capable of vibrating and outputting sound, and a second position protruding from the first position in the direction of sound output, a voice coil 3f that drives the diaphragm 3a according to an input signal, and a signal supply unit (signal amplification circuits C1, C2a, C2b, C2c, C3) that supplies a signal to the voice coil 3f so that the diaphragm 3a moves by switching between the first position and the second position.

[0082] In the earphones 51 and 52 according to this disclosure, the signal supply unit (for example, signal amplification circuits C1, C2a, C2b, and C2c) can input a signal to the voice coil 3f by switching between a path via a capacitor 13 that removes the DC component of the signal and a path with the capacitor 13 short-circuited. When the signal is input to the voice coil 3f via the path with the capacitor 13 short-circuited, the diaphragm 3a protrudes from a first position to a second position.

[0083] In the earphones 51 and 52 according to this disclosure, the signal supply unit (for example, signal amplification circuits C2a, C2b, C2c, C3) has a first amplification circuit AMP1 that inputs the amplified signal obtained by amplifying the signal to the voice coil 3f, and the voice coil 3f is made to protrude its diaphragm 3a from a first position to a second position when a DC voltage based on the power supply of the first amplification circuit AMP1 is input to it.

[0084] In the earphones 51 and 52 according to this disclosure, the signal supply unit (for example, the signal amplification circuit C2b) has a second amplification circuit AMP2 that inverts the amplified signal output from the first amplification circuit AMP1, and the first amplification circuit AMP1, the second amplification circuit AMP2, and the voice coil 3f are connected in a BTL configuration.

[0085] In the earphones 51 and 52 according to this disclosure, the signal supply unit (for example, the signal amplification circuit C3) outputs a signal S4 whose voltage value fluctuates in accordance with the vibration of the diaphragm 3a, centered around a midpoint voltage, when the diaphragm 3a is vibrated, and sets the midpoint voltage to a first midpoint voltage P1 when the diaphragm 3a is positioned in a first position, and sets the midpoint voltage to a second midpoint voltage P2 which is different from the first midpoint voltage P1 when the diaphragm 3a is positioned in a second position.

[0086] The earphones 51 and 52 described above do not require a complex housing structure, which is expected to improve yield in the manufacturing process, reduce component costs, and decrease market defects.

[0087] The technical scope of the present invention is not limited to the embodiments described above, and modifications can be made as appropriate without departing from the spirit of the invention. For example, in each of the above descriptions, a configuration in which switches SW1, SW1a, SW2, and SW3 are provided on the housing 2 was used as an example, but the invention is not limited to this configuration. For example, a configuration in which signals corresponding to the ON state and OFF state of switches SW1, SW1a, SW2, and SW3 are supplied to the earphones 51 and 52 from an external source by wireless communication such as short-range wireless communication. Also, in each of the above descriptions, the ON state and OFF state of switches SW1, SW1a, SW2, and SW3 are switched in accordance with the operation of the operation unit 8, but the timing of inserting and removing the earphones 51 and 52 may be detected by a sensor or the like, and the ON state and OFF state of switches SW1, SW1a, SW2, and SW3 may be switched according to that timing. For example, a contact sensor, proximity sensor, or pressure sensor may be provided, and the timing of inserting and removing the earphones 51 and 52 may be detected based on the detection results of these sensors.

[0088] The above explanation describes the case of canal-type earphones 51 and 52, but acoustic tube-type earphones or headsets may also be used. [Explanation of Symbols]

[0089] 1. Main body 2 eartips 3 Speaker Units 3a Diaphragm 3f voice coil 4a Sound cylinder part 7 Baffles 11 Audio playback unit 12, 13 Capacitors 17 Bypass switch 18 Bypass switch control unit 19 Midpoint Voltage Control Unit 51, 52 Earphones 61 Auricle 62 External auditory canal 63 Eardrum A1, A2 operational amplifiers AMP1, AMP2 Inverting Amplifier C1, C2a, C2b, C2c, C3 signal amplification circuit KN Knob L1, L2 protrusion amount SW1, SW1c, SW2, SW3 switches VR1 Variable Resistor

Claims

1. The casing and A first position provided within the housing that vibrates and can output sound, and sound from the first position A diaphragm is provided that is movable between a second position protruding in the direction of outputting, A voice coil that drives the diaphragm in response to an input signal, The diaphragm moves to switch between the first position and the second position. The system comprises a signal supply unit that supplies the aforementioned signal to the voice coil, The signal supply unit has a path through a capacitor that removes the DC component of the signal, and the capacitor The signal can be input to the voice coil by switching between a path with the passiter shorted and a path with the passiter shorted. The voice coil is configured such that the signal is input through a path that shorts the capacitor. The diaphragm is made to protrude from the first position to the second position. Earphones characterized by the following features.

2. The signal supply unit provides a first signal that amplifies the signal and inputs the amplified signal to the voice coil. It has an amplification circuit, The voice coil receives a DC voltage based on the power supply of the first amplification circuit. Furthermore, the diaphragm is made to protrude from the first position to the second position as described in claim 1. The included earphones.

3. The casing and A first position provided within the housing that vibrates and can output sound, and sound from the first position A diaphragm is provided that is movable between a second position protruding in the direction of outputting, A voice coil that drives the diaphragm in response to an input signal, The diaphragm moves to switch between the first position and the second position. The system comprises a signal supply unit that supplies the aforementioned signal to the voice coil, The signal supply unit provides a first signal that amplifies the signal and inputs the amplified signal to the voice coil. It has an amplification circuit, The voice coil receives a DC voltage based on the power supply of the first amplification circuit. To cause the diaphragm to protrude from the first position to the second position, Earphones characterized by the following features.

4. The signal supply unit provides a second signal that inverts the amplified signal output from the first amplification circuit. It has an amplification circuit, The first amplification circuit, the second amplification circuit, and the voice coil are connected in a BTL configuration. The earphone according to claim 3.

5. When switching the position of the voice coil to the second position, the following is supplied to the voice coil. It further comprises a voltage control unit that controls the DC voltage of the signal. The earphone according to claim 3.

Images