WO2006100911A1

WO2006100911A1 - Portable apparatus with built-in fm transmitter

Info

Publication number: WO2006100911A1
Application number: PCT/JP2006/304463
Authority: WO
Inventors: Hiroshi Miyagi; Takeshi Ikeda; Akira Okamoto
Original assignee: Niigata Seimitsu Co., Ltd.
Priority date: 2005-03-18
Filing date: 2006-03-08
Publication date: 2006-09-28
Also published as: CN101142749A; JPWO2006100911A1; GB2438135A; TW200637177A; GB0716779D0

Abstract

A portable apparatus with a built-in FM transmitter, where an antenna has a high degree of freedom in installation, less likely to break, and has enhanced transmission efficiency. A portable music playback apparatus (100) comprises an audio playback device (10) for generating an audio signal to be transmitted, a stereo modulation circuit (22) and an FM modulation circuit (24) for FM-modulating the audio signal to generate a carrier wave signal receivable by an FM receiver, an external transmission antenna (102) removably provided exposed to the outside of a housing, and a transmission circuit (26) for transmitting the carrier wave signal through the external transmission antenna (102).

Description

Specification

Mobile device with built-in FM transmitter

Technical field

TECHNICAL FIELD [0001] The present invention relates to a portable device having an FM transmitter including an FM transmitter that transmits an FM-modulated signal.

Background art

[0002] Conventionally, portable devices such as cellular phones with built-in FM transmitters are known (for example, see Patent Document 1). O Occurred in a portable device by using a built-in FM transmitter. Audio can be output from an external FM receiver. This makes it possible to output sound generated by a portable device that does not have the power from an external speaker, or to improve sound quality and ensure volume compared to using a small built-in speaker. It becomes possible. Further, as an antenna connected to an FM transmitter built in a portable device, an externally attached rod-shaped antenna is known (for example, see Patent Document 2).

Patent Document 1: Japanese Unexamined Patent Publication No. 2001-197168 (Page 3-6, Fig. 1-5)

Patent Document 2: Japanese Patent Laid-Open No. 10-207972 (Pages 4-7, Fig. 1-9)

Disclosure of the invention

Problems to be solved by the invention

By the way, as disclosed in Patent Document 2 described above, when a rod-shaped antenna is always externally attached, there is a risk of damage during storage or transportation. Although it may be possible to incorporate such a rod-shaped antenna, it is difficult to reduce the overall size of the device, and it is necessary to secure a space for housing the antenna in the housing, so that the degree of freedom of antenna installation is increased. There is a problem that the transmission efficiency decreases because the number of antennas decreases and a small antenna is used.

[0004] The present invention was created in view of these points, and an object of the present invention is to improve the transmission efficiency with a high degree of freedom of antenna installation and a low risk of damage. The purpose is to provide a portable device with a built-in transmitter. Means for solving the problem

[0005] In order to solve the above-described problems, a portable device incorporating an FM transmitter according to the present invention includes an audio signal generation circuit that generates an audio signal to be transmitted, and an FM receiver by FM-modulating the audio signal. A modulation circuit that generates a carrier wave signal that can be received by the mobile phone, an external transmission antenna that is exposed outside the housing and is detachable, and a transmission circuit that transmits the carrier wave signal through the external transmission antenna! / Speak. By using a removable external transmission antenna, it is only necessary to attach the antenna when necessary (only during transmission) .Therefore, the degree of freedom in installing the antenna is high, and the antenna may be damaged during transportation and storage. Can be prevented. In addition, it is possible to use a longer antenna than in the case of built-in, so that transmission efficiency can be increased.

[0006] Further, it is desirable that a loading coil is inserted in a part of the above-described external transmission antenna. Alternatively, it is desirable to further include an external antenna terminal provided in the housing described above and connected to the output terminal of the transmission circuit, and a loading coil is inserted between the output terminal of the transmission circuit and the external antenna terminal. As a result, the antenna length can be adjusted in accordance with the frequency of the transmitted carrier wave signal.

[0007] In addition, it is desirable to further include an output circuit that outputs the audio signal generated by the audio signal generation circuit described above, and to use a pluggable earphone cord connected to the output circuit as an external transmission antenna. As a result, since the earphone for listening to the audio sound can be used as an external transmission antenna, the number of parts can be reduced by eliminating the external transmission antenna as a separate part. In addition, since it is not necessary to provide an external antenna terminal dedicated to the external transmission antenna, the number of parts associated with this reduction can be reduced and the structure can be simplified.

[0008] Further, it is desirable to insert a choke coil between the transmission circuit and the output circuit described above. Thus, when a transmission signal is output from the transmission circuit toward the earphone cord, the transmission signal can be prevented from flowing into the output stage of the output circuit having a low output impedance.

[0009] Furthermore, a power supply circuit that receives power supply from a rechargeable secondary battery and supplies an operating voltage to each component is further provided, and the secondary battery is supplied from a commercial power supply cable via a power cable. It is charged when a charger that lowers and rectifies the AC voltage generated is connected, uses the power cable as an external transmission antenna, and electrically connects the transmission circuit and power cable via the internal wiring of the charger. It is desirable to connect. This makes it possible to use the power cable drawn from the charger as an external transmission antenna when the portable device is set in the charger to charge the built-in secondary battery. In addition, an external transmission antenna as a separate component is not necessary, and the number of components can be reduced and the structure of the portable device can be simplified.

[0010] In addition, the power cable described above has one end connected to the charger and the other end provided with an insertion plug corresponding to a household outlet. It is desirable to insert a choke coil in a position close to the other end provided. As a result, it is possible to remove power supply noise that enters from a household outlet when the power cord is used as an external transmission antenna.

[0011] In addition, the power supply circuit further supplies a rechargeable secondary battery power supply to supply an operating voltage to each component, and steps down an AC voltage supplied from a commercial power supply via a power cable. In addition, the secondary battery is charged by supplying a rectified charging current. The external transmission antenna is electrically connected to the charger antenna terminal provided on the charger casing, and is connected via the internal wiring of the charger. Therefore, it is desirable to electrically connect the transmission circuit and the external transmission antenna. This makes it possible to use the external transmission antenna attached to the charger when the portable device is set in the charger to charge the built-in secondary battery. Therefore, the portable device itself does not need an external antenna terminal, and thus the structure can be simplified.

[0012] Further, it is desirable that the external transmission antenna and the transmission circuit described above are separated from each other in a direct current manner. Specifically, the DC separation described above is performed by capacitive coupling via a capacitor. Alternatively, the DC separation described above is performed by electromagnetic coupling using a transformer. This makes it possible to protect the transmission circuit when the external transmission antenna comes into contact with a fixed potential or a ground potential.

[0013] In addition, it is desirable to further include an internal transmission antenna built in a casing connected to the transmission circuit described above. From this, the receiver is used when only the internal transmitting antenna is used. 1. You can't get enough signal quality on the side! / Only use an external transmit antenna! Therefore, handling of the portable device becomes easy when the external transmitting antenna is not used.

[0014] Further, the audio signal generation circuit described above is preferably recorded as a compressed format !, and is preferably an audio reproduction device that decompresses audio data and reproduces an audio signal. This makes it possible to transmit the audio signal reproduced by a small compressed audio playback device with excellent portability, such as an MP3 (MPEG Audio Layer-3) player, as an FM signal. Audio sound can be output from speakers such as home FM receivers.

Brief Description of Drawings

FIG. 1 is a diagram showing a configuration of a portable music playback device of a first embodiment.

FIG. 2 is a perspective view showing an appearance of a portable music player.

FIG. 3 is a diagram showing a modification of the present embodiment.

FIG. 4 is a diagram showing another modification of the present embodiment.

FIG. 5 is a diagram showing another modification of the present embodiment.

FIG. 6 is a diagram showing a configuration of a portable music playback device of a second embodiment.

FIG. 7 is a diagram showing a configuration of a portable music playback device of a third embodiment.

FIG. 8 is an external perspective view of charger 300.

FIG. 9 is a diagram showing a configuration of a portable music playback device of a fourth embodiment.

Explanation of symbols

[0016] 10 audio playback device

12 Output circuit

20 FM transmitter

22 Stereo modulation circuit

24 FM modulation circuit

26 Transmitter circuit

30 Operation unit

32 Display 36 Power supply circuit

38 Secondary battery

40, 108, 314, 322 loading coils

42, 46, 320 capacitors

44 coils

48, 334, 336 choke coil

100, 100A, 100B Portable music player

102 External transmit antenna

104, 116A, 116B, 118 External antenna terminal

106 Earphone jack

110 Earphone

110A earphone cord

112A, 112B, 114A, 114B charging terminal

200, 400 housing

300, 300A charger

310 Step-down circuit

312 Rectifier circuit

330 Power cable

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, a portable music playback device according to an embodiment to which the present invention is applied will be described in detail with reference to the drawings.

[First Embodiment]

FIG. 1 is a diagram showing the configuration of the portable music playback device of the first embodiment. A portable music playback device 100 of the present embodiment shown in FIG. 1 includes an audio playback device 10, an output circuit 12, an FM transmitter 20, an operation unit 30, a display unit 32, a control unit 34, a power supply circuit 36, and a secondary battery 38. It consists of Among these configurations, most configurations except the operation unit 30, the display unit 32, and the secondary battery 38 are formed on a semiconductor substrate as a one-chip component using a CMOS process or a MOS process (however, these components are not included). Cannot be formed by the process Except for the drive mechanism). By using these processes, it is possible to reduce the size and power consumption of the one-chip component formed on the semiconductor substrate and the portable music player 100 as a whole.

The audio playback device 10 is an audio signal generation circuit that expands audio data recorded in a compressed format and plays back and outputs an audio signal. For example, the audio playback device 10 is used in an MP3 player, an MD (mini disc) player, It corresponds. Note that the audio playback device 10 in the present embodiment needs at least a function for generating an audio signal to be transmitted, such as a CD (compact disc) player or a mobile phone that plays back an uncompressed audio data force audio signal. The audio reproduction device 10 may be configured by the audio reproduction circuit. The audio playback device 10 outputs L and R signals, which are separate left and right audio signals. The output circuit 12 outputs a signal obtained by amplifying the audio signal output from the audio playback device 10 and adjusting the sound quality to an earphone (not shown) via the earphone terminal 106.

The FM transmitter 20 transmits a signal after performing FM modulation on the L signal and the R signal output from the audio playback device 10 from the external transmission antenna 102 via the external antenna terminal 104. For this purpose, the FM transmitter 20 includes a stereo modulation circuit 22, an FM modulation circuit 24, and a transmission circuit 26. The stereo modulation circuit 22 performs a stereo modulation process that combines the input L signal and R signal to generate a stereo composite signal (stereo composite signal). The FM modulation circuit 24 performs FM modulation processing on the stereo composite signal, and generates a carrier wave signal that can be received by an external FM receiver (not shown) installed in the vicinity of the portable music playback device 100. . The transmission circuit 26 amplifies the carrier wave signal generated by the FM modulation circuit 24 and transmits it from the external transmission antenna 102.

The operation unit 30 includes various keys and operation knobs for accepting operations by the user. For example, a “play” key and a “stop” key are provided to give various instructions to the playback operation of the audio signal by the audio playback device 10, and a volume is used to indicate the degree of amplification of the output circuit 12. It has “UP” key and “DOWN” key for setting. The display unit 32 displays the content of the operation performed by the operation unit 30 and the content reproduced by the audio playback device 10 (for example, the name of the music being played (song name) and Such as the name of the artist and elapsed playback time). The control unit 34 controls the entire portable music player 100. For example, the playback state by the audio playback device 10 is set, or the volume is set by using the output circuit 12.

The power supply circuit 36 is applied with a terminal voltage of the secondary battery 38 and generates an operating voltage to be supplied to each part of the portable music playback device 100. Actually, an excessive voltage applied between the power circuit 36 and the secondary battery 38, or between the secondary battery 38 and the charging terminals 112A and 114A exposed to the outside, such as an external force, Although a protection circuit for protecting the secondary battery 38 and the power supply circuit 36 from noise and the like is provided, this protection circuit is omitted in FIG.

FIG. 2 is a perspective view showing the external appearance of the portable music playback device 100. As shown in FIG. 2, the housing 200 of the portable music playback device 100 is provided with an external antenna terminal 104 exposed to the outside, and the external transmission antenna 102 can be detachably attached to the external antenna terminal 104. Be attached. As shown in FIG. 2, the external transmission antenna 102 has, for example, a rod shape, and can be attached to the housing 200 by fitting one end of the external transmission antenna 102 into the external antenna terminal 104. The external transmission antenna 102 may be attached to the external antenna terminal 104 by forming a male screw groove at one end of the external transmission antenna 102 and a female screw groove at the external antenna terminal 104. Further, the shape of the external transmission antenna 102 may be a string shape that does not necessarily need to be a rod shape, or may have a bent shape such as an L shape.

As described above, since the portable music playback device 100 according to the present embodiment uses the removable external transmission antenna 102, the antenna may be attached only when necessary (only during transmission). Therefore, even if the antenna installation flexibility is high, it is possible to prevent the external transmission antenna 102 from being damaged during transportation or storage. In addition, since it is possible to use an external transmission antenna that is longer than the built-in case, transmission efficiency can be increased.

FIG. 3 is a view showing a modification of the present embodiment. In the configuration of the modification shown in FIG. 3, the loading coil 40 is inserted between the transmission circuit 26 and the external transmission antenna 102. By using the loading coil 40 as a part of the external transmission antenna 102, the effective length of the external transmission antenna 102 can be increased. In the configuration shown in FIG. The force of inserting the ing coil 40 between the transmitting circuit 26 and the external antenna terminal 104 The loading coil 40 may be inserted into a part of the external transmitting antenna 102 externally attached to the external antenna terminal 104. Further, in order to effectively use the space, the loading coil 40 may be formed by winding a copper wire around the outer antenna terminal 104.

FIG. 4 and FIG. 5 are diagrams showing another modification of the present embodiment. In the configuration of the modification shown in these drawings, the transmission circuit 26 and the external transmission antenna 102 are separated from each other in a direct current manner. Specifically, in the example shown in FIG. 4, by inserting a capacitor 42 between the transmission circuit 26 and the external antenna terminal 104, the transmission circuit 26 and the external transmission antenna 102 are connected via a capacitance ( Capacitive coupling). Further, in the example shown in FIG. 5, by inserting two coils 44 that are electromagnetically coupled to each other between the transmission circuit 26 and the external antenna terminal 104, the transmission circuit 26 and the external transmission antenna 102 are electromagnetically coupled. ing. This makes it possible to protect the transmission circuit 26 when the external transmission antenna 102 comes into contact with a fixed potential or a ground potential.

[Second Embodiment]

FIG. 6 is a diagram showing the configuration of the portable music playback device of the second embodiment. The portable music playback device 100A of the present embodiment shown in FIG. 6 has substantially the same configuration as the portable music playback device 100 shown in FIG. 1, and externally transmits a pluggable earphone cord connected to the output circuit 12. The difference is that it is used as an antenna. In the configuration shown in FIG. 6, the output terminal of the transmission circuit 26 in the FM transmitter 20 is connected to the wiring between the output circuit 12 and the earphone terminal 106 via the capacitor 46 for DC separation. Further, between the output circuit 12 and the earphone terminal 106, a choke coil 48 is inserted on the output circuit 12 side, and a loading coil 108 is inserted on the earphone terminal 106 side, respectively. The signal output from the transmission circuit 26 is input to the connection point of the choke coil 48 and the loading coil 108 via the capacitor 46, and the earphone cord 110A of the earphone 110 is externally transmitted via the loading coil 108 and the earphone terminal 106. Sent as an antenna.

[0028] As described above, since the earphone cord 110A of the earphone 110 that listens to the audio sound can be used as an external transmission antenna, the external transmission antenna 102 as a separate component is not provided. In this way, the number of parts can be reduced. In addition, since it is not necessary to provide the external antenna terminal 104 dedicated to the external transmitting antenna, the number of parts associated with this can be reduced and the structure can be simplified.

[0029] Since the output impedance of the output stage of the output circuit 12 is generally low, if the output terminal of the transmission circuit 26 is directly connected to the output stage of the output circuit 12, a transmission signal flows into the transmission circuit 26. Output By inserting the choke coil 48 on the output side of the circuit 12, it is possible to prevent such a transmission signal from flowing into the output circuit 12.

[Third Embodiment]

FIG. 7 is a diagram showing the configuration of the portable music playback device of the third embodiment, showing the overall configuration of the portable music playback device system including the charger! / The portable music playback device 100B of the present embodiment shown in FIG. 7 has substantially the same configuration as the portable music playback device 100 shown in FIG. 1, and the external antenna terminal 104 is provided in the vicinity of the charging terminals 112A and 114A. The external antenna terminal 116A is replaced.

[0031] In addition, a charger 300 used for charging the built-in secondary battery 38 is externally attached to the portable music playback device 100B of the present embodiment. The charger 300 includes a step-down circuit 310 that steps down an AC voltage that is also supplied with commercial power via a power supply line 330, and a rectifier circuit 312 that rectifies the stepped-down AC voltage to generate a DC charging current. ing. For example, in the simplest case, the step-down circuit 310 is constituted by a transformer, and the rectifier circuit 312 is constituted by a bridge circuit using a rectifier element such as a diode. The positive and negative output terminals of the rectifier circuit 312 are connected to the charging terminals 112B and 114B exposed to the outside. These charging terminals 112B and 114B are provided at positions that are electrically connected to the charging terminals 112A and 114A on the portable music playback device 100B side when the portable music playback device 100B is set at a predetermined position of the charger 300. Yes. Thereby, the charging current generated by the charger 300 is supplied to the secondary battery 38 via the charging terminals 112A and 112B and the charging terminals 114A and 114B.

FIG. 8 is an external perspective view of the charger 300, and shows a state where the casing 200B of the portable music playback device 100B is set. The charger 300 according to the present embodiment includes an external antenna terminal 116B provided in the vicinity of the charging terminals 112B and 114B, and a part of the casing of the charger 300. And an external antenna terminal 118 provided at a position exposed to the outside, and a loading coil 314 inserted between these external antenna terminals 116B and 118. The external antenna terminal 116B is provided at a position that is electrically connected to the external antenna terminal 116A on the portable music playback device 100B side when the portable music playback device 100B is set at a predetermined position of the charger 300. The external antenna terminal 118 has the same function as the external antenna terminal 104 shown in FIGS. 1 and 2, and the external transmission antenna 102 is detachably attached. In the present embodiment, the external antenna terminal 118 to which the external transmission antenna 102 is attached is provided on the casing 400 of the charger 300. Therefore, it is not always necessary to use the removable external transmission antenna 102. The transmitting antenna 102 may be attached to the external antenna terminal 118 in a non-removable state. Since the loading coil 314 is for adjusting the antenna length, it may be omitted.

[0033] Thus, when the portable music player 100B is set in the charger 300 in order to charge the built-in secondary battery 38, the external transmission antenna 102 attached to the charger 300 can be used. It becomes possible. Accordingly, the portable music player 100B itself does not require an external antenna terminal, and thus the structure can be simplified.

[Fourth Embodiment]

FIG. 9 is a diagram showing the configuration of the portable music playback device of the fourth embodiment, showing the overall configuration of the portable music playback device system including the charger. A portable music player 100B of the present embodiment shown in FIG. 9 is the same as that shown in FIG. 7, and includes an external antenna terminal 116A.

[0035] In addition, the charger 300A removes the external antenna terminal 118 and the loading coil 314 connected thereto from the charger 300 shown in FIG. 7, and instead connects to the external antenna terminal 116B. The difference is that a DC separating capacitor 320, a loading coil 322 inserted into the power cable 330, and two choke coils 334 and 336 are added. The two choke coils 334 and 336 are for removing power noise entering from the household outlet, and are closer to the end of the plug 332 side than the end of the step-down circuit 310 side of the power cable 330 Inserted in position. In addition, loading The coil 322 is for adjusting the antenna length and may be omitted.

[0036] By using such a charger 300A, when the portable music player 100B is set in the charger 300A in order to charge the built-in secondary battery 38, a power source drawn from the charger 300A is used. The cable 330 can be used as an external transmitting antenna. However, an external transmission antenna as a separate part is not required, and the number of parts can be reduced and the structure of the portable music playback device 100B can be simplified.

[0037] It should be noted that the present invention is not limited to the above embodiment, and various modifications can be made within the scope of the gist of the present invention. For example, in the above-described embodiment, the force described only focusing on the detachable external transmission antenna. In addition to the detachable external transmission antenna, the internal transmission antenna may be built in the portable music playback device 100 or the like. Good

. In this case, when using the internal transmission antenna and the external transmission antenna at the same time, it is desirable that these connections be made via a balun so that no impedance mismatch occurs. In this way, when the internal transmission antenna and the external transmission antenna are used in combination, the external transmission antenna only needs to be used when sufficient signal quality cannot be obtained on the FM receiver side when only the internal transmission antenna is used. . Therefore, when the external transmission antenna is not used, the external transmission antenna that protrudes from the housing 200 of the portable music playback device 100 or the like can be removed. Is easy to handle.

Industrial applicability

[0038] According to the present invention, by using a detachable external transmission antenna, only when necessary.

(Only at the time of transmission) Since it is only necessary to attach an antenna, the antenna can be prevented from being damaged during transportation and storage even when the antenna has a high degree of freedom in installation. In addition, since it is possible to use a longer antenna than in the case of built-in, transmission efficiency can be increased.

Claims

The scope of the claims

[1] an audio signal generation circuit for generating an audio signal to be transmitted;

A modulation circuit for FM-modulating the audio signal to generate a carrier wave signal that can be received by an FM receiver;

An external transmission antenna that is exposed to the outside of the housing and is detachable;

A portable circuit with a built-in FM transmitter, comprising: a transmission circuit that transmits the carrier wave signal through the external transmission antenna.

[2] In claim 1,

The external transmission antenna is a portable device with a built-in FM transmitter in which a loading coil is inserted.

[3] In claim 2,

An external antenna terminal provided in the housing and connected to an output terminal of the transmission circuit;

A portable device with a built-in FM transmitter in which a loading coil is inserted between the output terminal of the transmission circuit and the external antenna terminal.

[4] In claim 1,

An output circuit for outputting an audio signal generated by the audio signal generation circuit;

A portable device with a built-in FM transmitter that uses a pluggable earphone cord connected to the output circuit as the external transmission antenna.

[5] In claim 4,

A portable device with a built-in FM transmitter in which a choke coil is inserted between the transmission circuit and the output circuit.

[6] In claim 1,

Rechargeable secondary battery power A power supply circuit that further receives power supply and supplies operating voltage to each component is further provided.

The secondary battery is charged when a charger that rectifies and rectifies an AC voltage supplied from a commercial power supply via a power cable is connected, A portable device with a built-in FM transmitter that uses the power cable as the external transmission antenna and electrically connects the transmission circuit and the power cable via an internal wiring of the charger.

[7] In claim 6,

The power cable has one end connected to the charger and the other end provided with a plug corresponding to a household outlet.

A portable device with a built-in FM transmitter in which a choke coil is inserted closer to the other end side where the insertion plug is provided than to one end side of the power cable.

[8] In claim 1,

A charger antenna terminal provided on a case of a charger that charges the secondary battery by supplying a rectified charging current while stepping down an AC voltage supplied from a commercial power supply via a power cable. The external transmitting antenna is electrically connected;

A portable device with a built-in FM transmitter that electrically connects the transmission circuit and the external transmission antenna via the internal wiring of the charger.

[9] In claim 1,

The portable device with a built-in FM transmitter, wherein the external transmission antenna and the transmission circuit are galvanically separated from each other.

[10] In claim 9,

The DC separation is performed by capacitive coupling through a capacitor. A portable device with a built-in FM transmitter.

[11] In claim 9,

The DC separation is a portable device with a built-in FM transmitter that performs electromagnetic coupling using a transformer.

[12] In claim 1,

A portable device with a built-in FM transmitter, further comprising an internal transmission antenna built in the housing connected to the transmission circuit.

[13] In claim 1,

The audio signal generation circuit is a portable device having an FM transmitter, which is an audio playback device that decompresses audio data recorded in a compressed format and reproduces the audio signal.

[14] In claim 1,

A CMOS process is! / Is a portable device with a built-in FM transmitter in which a structure corresponding to the audio signal generation circuit, the modulation circuit, and the transmission circuit is formed on a semiconductor substrate using a MOS process.

[15] In claim 1,

The audio signal generation circuit is an MP3 player, a portable device with a built-in FM transmitter.

[16] In claim 1,

The audio signal generation circuit is an MD player, a portable device with a built-in FM transmitter.

[17] In claim 1,

The audio signal generation circuit is a CD player.

[18] In claim 1,

The audio signal generation circuit is a mobile phone.