JP2006148772A - Speaker unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a speaker unit capable of avoiding performance degradation due to heat dissipation or spurious radiation in an electronic circuit within a personal digital assistant, when the personal digital assistant is used. <P>SOLUTION: As shown in Figure (a), a digital amplifier 52 is attached at a yoke 44a constituting a cabinet of a speaker unit 41 together with a frame 42 formed with metal. An output current is supplied from the digital amplifier 52 to the speaker unit 41 by contact with a contact terminal 57 at a terminal portion 47. As shown in Figure (b), a bare chip 53 is directly packaged on a digital amplifier substrate 55 using a WL-Chip Scale Package (Wafer Level Chip Size Package), and a peripheral circuit component 54 of the bare chip 53 is packaged, and the contact terminal 57 is attached at a speaker connecting terminal. As shown in Figure (c), the frame 42 is connected with the yoke 44a thermally and electrically to enable installation of the digital amplifier 52. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a speaker unit, and more particularly to a speaker unit incorporating a digital amplifier.

  In recent years, in portable information terminals such as cellular phones, with the progress of miniaturization and high functionality, circuit components have been made into ICs (Integrated Circuits), and most circuits are configured on one main circuit board in a cellular phone. Can be done. However, it is difficult to directly attach components that need to be closely attached to the housing, such as a speaker for reception, to be connected to the main circuit board via a connection member. There are many.

  Conventionally, as shown in FIG. 5, the speaker unit 41 is connected to the main circuit board 1 via a signal line 31. More specifically, the circuit component 2 and the key switch group 3 are mounted on the main circuit board 1, and a terminal attached to a yoke (a yoke) 44a that forms a housing of the speaker unit 41 together with a frame 42 made of metal. A signal line 31 is connected to an output terminal of an amplifier 21 that forms part of the circuit component 2.

  However, in the above-described conventional speaker unit 41, the amplifier 21 that generates heat during operation is mounted on the main circuit board 1 that is mounted in a limited space in the casing of the portable information terminal, and thus heat is radiated to the amplifier 21. There was a problem that a heat radiating member such as a plate could not be attached and the performance of the electronic circuit formed on the main circuit board 1 was deteriorated by the heat generated by the amplifier 21.

As a countermeasure, for example, as disclosed in Patent Document 1, a circuit board such as an amplifier is fixed to a mounting surface of a holding member that holds a vibration generating unit and has an area larger than the main surface of the circuit board. A speaker that radiates heat generated from an electronic component attached to the circuit board by a holding member has been developed.
Further, as a conventional example for dealing with the problem of heat dissipation of electronic components, for example, as disclosed in Patent Document 2, a power amplifier is thermally connected to an antenna and a part of heat generated by the power amplifier is generated. Wireless communication devices have been developed that dissipate the light with an antenna.
JP 2000-13877 A JP 2003-218729 A

However, since the speaker disclosed in Patent Document 1 releases heat generated by the electronic components on the circuit board by the holding member, the degree of heat radiation is better than that before attaching the circuit board to the holding member. In such a limited space as in the case, there is a problem that heat to escape from the holding member is trapped, and heat dissipation performance cannot be expected.
In addition, since the wireless communication device disclosed in Patent Document 2 releases part of the heat generated by the power amplifier by the antenna, heat radiation is dissipated depending on whether the telescopic antenna is extended or stored in the portable information terminal. When the effect is changed and the antenna is stored, there is a problem that the heat dissipation performance cannot be expected.

  Further, by changing the amplifier 21 mounted on the main circuit board 1 from a linear amplifier in which heat generation is a problem to a digital amplifier that is excellent in power efficiency and alleviates the problem of heat generation, problems related to heat dissipation can be avoided. Can be considered. However, the output signal of the digital amplifier contains a lot of harmonics. When the output signal is passed through the signal line 31, unnecessary radiation Rad is emitted from the signal line 31, and the operation of the electronic circuit in the portable information terminal is performed. There was a problem that caused another problem of affecting.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to avoid the problem of deterioration of the performance of the electronic circuit inside the portable information terminal due to heat radiation or unnecessary radiation, for example, when used in the portable information terminal. It is to provide a speaker unit capable of

In order to achieve the above object, the present invention proposes the following means.
According to a first aspect of the present invention, there is provided a magnet, a yoke that is in contact with the magnet and forms a magnet circuit unit, a vibration unit that is attached to a coil provided in the magnet circuit unit, the magnet circuit unit, and the vibration And a digital amplifier that supplies a current corresponding to an audio signal to the coil, and the digital amplifier is attached to the frame part or the yoke.
According to the present invention, the digital amplifier is directly attached to the speaker unit while shortening the signal line to the speaker unit as much as possible.

The invention of claim 2 is the speaker unit according to claim 1, wherein a main part of the circuit of the digital amplifier is constituted by a bare chip, and the bare chip is directly mounted on a circuit board of the digital amplifier. Features.
According to the present invention, the bare chip is mounted on the circuit board while minimizing the mounting area occupied on the circuit board of the digital amplifier.

A third aspect of the present invention is the speaker unit according to the first or second aspect, wherein the frame portion is made of metal.
According to the present invention, the digital amplifier is electrically and thermally connected to the digital amplifier.

  According to the first aspect of the present invention, even if a digital amplifier is used which has a small problem of heat generation but a large problem of unnecessary radiation from the signal line, it is possible to minimize the generation of unnecessary radiation.

  According to the invention of claim 2, there is an effect that it is possible to take measures against unnecessary radiation of the digital amplifier using a small shield member or the like on the circuit board.

  According to the invention of claim 3, there is an effect that the digital amplifier can take measures against unnecessary radiation and can dissipate heat.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 2, the digital amplifier built-in speaker unit 51 has a configuration in which a digital amplifier 52 is directly attached to a yoke 44a that forms a housing of the speaker unit 41 together with a frame 42. It is electrically connected to the main body circuit board 1. The digital amplifier 52 is attached by being thermally connected to the yoke 44a and radiated by the yoke 44a. The flexible board 32 transmits a direct current for driving the digital amplifier 52 and an analog audio signal or a digital audio signal, which will be described later, from the main circuit board 1 to the speaker unit 51 with a built-in digital amplifier. The details of mounting the digital amplifier 52 to the speaker unit 41 in the digital amplifier built-in speaker unit 51 will be described later.

  The main body circuit board 1 is incorporated in a casing of a mobile phone (not shown), and constitutes most circuit patterns of the mobile phone. The circuit board 2 and the key switch group 3 are mounted on the main body circuit board 1, and a flexible board 32 is attached to be electrically connected to the speaker unit 51 with a built-in digital amplifier. In the main circuit board 1, another circuit component 22 is mounted in a region where the amplifier 21 is conventionally mounted.

  The circuit component 2 constitutes a circuit (control circuit, high frequency circuit, etc.) for realizing the function of the mobile phone. The key switch group 3 constitutes operation keys such as a numeric keypad, and realizes an operation assigned to each key when pressed by a user via a keypad (not shown) attached to the housing.

  3A and 3B are block diagrams showing an example of the circuit configuration of the digital amplifier 52. FIG. The digital amplifier 52 inputs an analog audio signal or a digital audio signal (PCM (Pulse Code Modulation) (pulse code modulation) signal) from the input terminal IN, performs PWM (Pulse Width Modulation) (pulse width modulation) conversion processing, The power of the processed PWM signal is amplified. The digital amplifier 52 outputs from the output terminal OUT to the speaker unit 41 via a low-pass filter (not shown).

  FIG. 3A shows one circuit configuration example of the digital amplifier 52. The digital amplifier 52 having the above circuit configuration includes a triangular wave generation circuit 151 that generates a triangular wave signal serving as a reference signal, a comparator 152, a power driver 153, a switching transistor 154 to which a power supply voltage + Vdd is supplied to a source, and a power supply to a source. The switching transistor 155 is supplied with the voltage −Vdd. The digital amplifier 52 receives an analog audio signal from the input terminal IN, and outputs a power-amplified PWM signal from an output terminal OUT that is a connection point between the drain of the switching transistor 154 and the drain of the switching transistor 155.

  In the digital amplifier 52 having the above circuit configuration, an analog audio signal is input to one input terminal of the comparator 152, and the comparator 152 compares the analog audio signal with the triangular wave signal output from the triangular wave generating circuit 151, thereby generating PWM. A signal is generated and output to the power driver 153. The power driver 153 drives the switching transistors 154 and 155 based on the PWM signal, and outputs a power amplified PWM signal from the output terminal OUT. This power-amplified PWM signal has a carrier frequency component removed by a low-pass filter, and is supplied to the speaker unit 41 as a power-amplified analog audio signal.

  FIG. 3B shows another circuit configuration example of the digital amplifier 52. The digital amplifier 52 having the above circuit configuration includes a ΔΣ modulation circuit 161, a PDM / PWM conversion circuit 162 that converts a pulse density modulation (PDM (Pulse Density Modulation)) signal into a PWM signal, a power driver 153, and a source. The switching transistor 154 is supplied with the power supply voltage + Vdd, and the switching transistor 155 is supplied with the power supply voltage -Vdd at the source. The digital amplifier 52 receives a digital audio signal from the input terminal IN, and outputs a power-amplified PWM signal from an output terminal OUT that is a connection point between the drain of the switching transistor 154 and the drain of the switching transistor 155.

  As shown in FIG. 1A, the digital amplifier 52 is attached to the yoke 44 a of the speaker unit 41. As shown in FIG. 1B, the digital amplifier 52 includes a bare chip 53 in which main parts of the circuit are integrated on a semiconductor substrate, a peripheral circuit component 54 of the bare chip 53, a bare chip 53, and a peripheral circuit component 54. The mounted digital amplifier circuit board 55 (circuit board), the speaker connection terminal 56 for taking out the output current of the digital amplifier 52, and the terminal portion 47 of the speaker unit 41 are brought into contact with the output current from the speaker connection terminal 56. The contact terminal 57 is supplied to 47.

  The bare chip 53 is directly attached on the digital amplifier circuit board 55 by WL-CSP (Wafer Level Chip Size Package). That is, the bare chip 53 is directly soldered to the digital amplifier circuit board 55 by solder balls. The contact terminal 57 is attached to the speaker connection terminal 56.

  As shown in FIG. 1C, the speaker unit 41 includes a frame 42 made of metal, a magnet 43, a yoke 44a, a center piece 44b, a voice coil 45 (coil), and a diaphragm 46 (vibration). Part), voice form 48 (vibrating part), edge 49a, and damper 49b. The terminal portion 47 is not shown.

  The inner periphery of the diaphragm 46 is fixed to the voice form 48, and the voice form 48 is supported on the inner periphery of the frame 42 via the damper 14. Further, the outer periphery of the diaphragm 46 is supported on the outer periphery of the frame 42 via the edge 49a, and thereby the diaphragm 46 is supported so as to be able to vibrate. The voice coil 45 is fixed to the voice form 48 so as to be disposed in a gap portion between the magnet 43 and the center piece 44b.

  The yoke 44a is fixed to the frame 42. An annular magnet 43 is fixed inside a cylindrical magnetic yoke 44a, and a columnar magnetic body center piece 44b is fixed to a cylindrical convex portion inside the yoke 44a. Therefore, the magnets 43 and 43, the yoke 44a, and the center piece 44b constitute a magnet circuit, and a magnetic field is formed between the magnet 43 and the center piece 44b.

  The voice coil 45 receives a current corresponding to the audio signal from the digital amplifier 52, and the voice coil 45 vibrates according to the current value by the magnetic flux in the gap. The voice coil 45 is connected to the diaphragm 46 via the voice form 48, and the diaphragm 46 vibrates in response to the vibration of the voice coil 45, and a sound corresponding to the audio signal is reproduced.

  Next, the operation of the mobile phone configured by incorporating the digital amplifier built-in speaker unit 51 and the main circuit board 1 in the housing in the present embodiment will be described with reference to FIG.

  First, the user depresses a specific key switch of the key switch group 3 by pressing a keypad of a specific key, and turns on the power of the mobile phone to make it operable. Then, a call is made by pressing the keypad corresponding to the numeric keypad.

  Then, a DC current and an analog audio signal or a digital audio signal are transmitted from the main circuit board 1 to the digital amplifier 52 via the flexible board 32 by the electronic circuit configured by the circuit component 2 during the call. The digital amplifier 52 amplifies the analog audio signal or the digital audio signal and outputs it to the speaker unit 41 through a low-pass filter. At this time, the heat generated from the digital amplifier 52 is radiated from the yoke 44a.

According to this embodiment, the digital amplifier 52 is directly connected to the speaker unit 41 while being thermally connected, so that the length of the signal line for supplying the signal from the digital amplifier 52 to the speaker unit 41 is minimized. Even if the digital amplifier 52 is used which has a small problem of heat generation but a large problem of unnecessary radiation from the signal line, generation of unnecessary radiation can be minimized.
In particular, in the cellular phone, the main circuit board 1 and the circuit components 2 are densely packed in a limited space in the housing, and heat generation or unnecessary radiation from the amplifier can be taken by a heat radiating member, a shield member, or the like. The present invention is effective because it is difficult to reduce heat generation from the amplifier or unnecessary radiation itself.

  Further, according to the present embodiment, since the bare chip 53 in which the main part of the circuit of the digital amplifier 52 is integrated on the semiconductor substrate is directly mounted on the digital amplifier circuit board 55 by WL-CSP, the bare chip 53 is digitally connected. The mounting area occupied on the amplifier circuit board 55 can be minimized, and a measure against unnecessary radiation can be taken by electrically connecting the yoke 44a with a small shield member or the like.

  In this embodiment, it is assumed that the bare chip 53 is directly attached to the digital amplifier circuit board 55 by WL-CSP, but may be attached by COB (Chip On Board).

  In the present embodiment, it is assumed that the digital amplifier 52 is attached to the yoke 44 a of the speaker unit 41, but the digital amplifier 52 may be attached to the frame 41. Here, since the frame 42 is formed of metal, it is possible to take measures against unnecessary radiation and to dissipate heat by attaching the frame 42 to the digital amplifier 52 in electrical and thermal connection.

Further, since the direct current for driving the digital amplifier 52 and the analog audio signal or the digital audio signal before being amplified by the digital amplifier 52 are transmitted to the pattern of the flexible substrate 32, the amplifier 21 is conventionally used. Since there is no signal line amplified by the above, that is, an AC line with high energy, the problem of unnecessary radiation can be avoided even if the output power of the digital amplifier 52 is increased.
In addition, as described above, since alternating current with high energy does not flow on the pattern of the flexible substrate 32, the length of the flexible substrate 32 can be increased within a range in which the loss of direct current is allowed, so In this case, the degree of freedom in arranging the speaker units can be increased.

  In addition, since the digital amplifier 52 is attached to the speaker unit 41, a space for mounting the amplifier is not required in the main circuit board 1, and another circuit component 22 is mounted in the space to improve the functionality of the mobile phone. Can be planned.

  Further, in the present embodiment, as described above, since high-energy alternating current does not flow on the pattern of the flexible substrate 32, the reduction of unnecessary radiation is significant, and the balance between the effect of reducing unnecessary radiation and cost. The digital amplifier 52 may be mounted on the digital amplifier circuit board 55 by ordinary mounting.

As a modification of the present embodiment, the digital amplifier 52 may be attached to the frame 42 via the attachment fitting 61 as shown in FIG. 4B and 4C, a digital amplifier 52 may be attached to the frame 42 via a mounting bracket 61 in a speaker unit 41a having a shape different from that of the speaker unit 41 described above. 4B and 4C are views of the digital amplifier built-in speaker unit 51a viewed from different angles. In this case, in the digital amplifier 52, the speaker connection terminal 56 and the terminal portion 47 are connected by the lead wire 62 instead of the contact terminal 57 shown in FIGS. Corresponding current is supplied.
Even if the digital amplifier 52 is attached to the frame 42 as described above, since the digital amplifier 52 is electrically and thermally connected to the frame 42, as in the basic embodiment, countermeasures against unnecessary radiation of the digital amplifier 52 and Heat can be dissipated.

  As mentioned above, although embodiment of this invention was explained in full detail with reference to drawings, the concrete structure is not restricted to this embodiment, The design change in the range which does not deviate from the summary of this invention is also included.

FIG. 3 is a diagram showing an attachment of the digital amplifier 52 to the speaker unit 41 and an internal structure of the digital amplifier 52 and the speaker unit 41 in the speaker unit 51 with a built-in digital amplifier according to an embodiment of the present invention. 4 is a diagram showing a configuration in which a digital amplifier built-in speaker unit 51 is connected to a main body circuit board 1 of a mobile phone in the embodiment. FIG. 3 is a block diagram illustrating a circuit configuration example of a digital amplifier 52 in the same embodiment. FIG. It is the attachment figure to the speaker units 41 and 41a of the digital amplifier 52 in the speaker units 51 and 51a with a built-in digital amplifier of the modification of one Embodiment of this invention. It is a figure which shows the structure which connected the speaker unit 41 to the main body circuit board 1 of the mobile telephone conventionally.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Main body circuit board, 2, 22 ... Circuit components, 3 ... Key switch group, 21 ... Amplifier, 31 ... Signal line, 32 ... Flexible board, 41, 41a ...・ Speaker unit, 42... Frame, 43 .. magnet, 44 a... Yoke (yoke), 44 b... Center piece, 45 .. voice coil (coil), 46. (Vibration part), 47 ... terminal part, 48 ... voice form (vibration part), 49a ... edge, 49b ... damper, 51, 51a ... speaker unit with built-in digital amplifier, 52 ... Digital amplifier 53 ... Bare chip 54 ... Peripheral circuit component 55 ... Digital amplifier circuit board (circuit board) 56 ... Speaker connection terminal 57 ... Contact terminal 61 ... Installation Money , 62 ... Lead wire, 151 ... Triangular wave generation circuit, 152 ... Comparator, 153 ... Power driver, 154, 155 ... Switching transistor, 161 ... ΔΣ modulation circuit, 162 ... PDM (Pulse Density Modulation) / PWM (Pulse Width Modulation) conversion circuit, Rad ... unnecessary radiation

Claims (3)

Magnets,
A yoke that is in contact with the magnet and forms a magnet circuit portion;
A vibration part attached to a coil provided in the magnet circuit part;
A frame part for holding the magnet circuit part and the vibration part;
A digital amplifier for supplying a current corresponding to an audio signal to the coil;
With
The speaker unit, wherein the digital amplifier is attached to the frame portion or the yoke. The main part of the circuit of the digital amplifier is constituted by a bare chip,
The bare chip is mounted directly on the circuit board of the digital amplifier;
The speaker unit according to claim 1. The speaker unit according to claim 1, wherein the frame portion is made of metal.

Images