TWI385885B - Multimedia device and volume control method - Google Patents

Description

Multimedia device and volume control method

The present invention relates to a multimedia mobile phone, and more particularly to a volume control method for protecting an ear.

The first figure is a conventional multimedia mobile phone 100, which includes a receiver 102 for playing the sound source signal #A. A sound hole 108 is connected between the receiver 102 and the casing for conducting the sound source signal #A. Thereby, the user can listen to the sound source signal #A by placing the sound hole 108 close to the ear. On the other hand, the multimedia mobile phone 100 further includes a speaker 112 for playing the sound source signal #A ' in a sound amplification manner. The sound source signal #A ' can be a ringtone of the incoming call, and the volume generated by the speaker 112 in order to enlarge the sound source signal #A ' is usually quite large. If the user just puts the ear close to the sound hole 108, it may be damaged by the sound.

In order to solve this problem, the conventional multimedia mobile phone 100 may additionally provide a sensor 106 for detecting the distance between the person's head and the multimedia mobile phone 100. The sensor 106 is typically an infrared sensor. When the ear is close to the sound hole 108, the sensor 106 sends a control signal #S to notify the processor 104 to cause the processor 104 to suppress the gain value of the sound source signal #A ' .

However, the addition of an additional sensor 106 is an increase in cost and system complexity.

The present invention provides a multimedia device in which a gain amplifier controls the gain of an audio source signal based on a control signal. A first speaker and a second speaker share a back air cavity, and when the first speaker plays the sound source signal, the second speaker generates an induced electromotive force. A detector is coupled to the second speaker for detecting the induced electromotive force and generating the control signal according to the induced electromotive force. When the induced electromotive force is greater than a threshold, the detector commands the gain amplifier to reduce the gain of the audio signal by the control signal, and reduces the playing volume of the first speaker.

The detector is a comparator having a first input receiving the induced electromotive force, a second input receiving the threshold, and outputting the comparison result as the control signal.

Further, a selector in the multimedia device can switchably select to output the sound source signal to the first speaker or the second speaker. A diode is coupled between the second speaker and the selector to prevent the induced electromotive force from being fed back from the second speaker to the selector.

When the selector selects to output the sound source signal to the second speaker, the detector is turned off. When the selector selects to output the sound source signal to the gain amplifier, the detector is turned on.

A first sound hole is connected to the first speaker for transmitting the sound emitted by the first speaker. A second sound hole is connected to the second speaker for transmitting the sound emitted by the second speaker. When the first speaker plays the sound source signal The sound film of the second speaker is vibrated and vibrated through the back air cavity, thereby driving the coil in the second speaker to generate the induced electromotive force.

The determination of the critical value is the induced electromotive force set according to the empirical value when the second sound hole is covered by the user's ear or other object and the amplitude of the second speaker sound film and the voice coil is different when the sound is not covered.

The multimedia device proposed by the present invention is particularly suitable for use in a mobile phone. The first speaker is a speaker, the second speaker is a receiver, and the sound source signal is an incoming ringtone or a calibration test tone.

In another embodiment, the present invention discloses a volume control method applied to the above multimedia device. First, the first speaker is caused to play an audio source signal. Then, an induced electromotive force generated by the second speaker is detected. If the induced electromotive force is greater than a threshold, the gain of the source signal is reduced.

The following examples specifically illustrate how the invention can be carried out in a preferred manner. The examples are for illustrative purposes only, and are not intended to limit the scope of the invention. The actual scope is subject to the scope of the patent application.

The architecture proposed by the present invention does not require an additional configuration of the infrared sensor, but directly uses the principle of mutual induction between the speaker and the receiver to determine the position of the ear. In a multimedia mobile phone, the same back air cavity is shared between the speaker and the receiver, so when the speaker emits a sound, the sound film and the coil of the receiver are vibrated to generate a small amount of induced electromotive force. The sound hole of the receiver, if it is outside When the object is covered, the magnitude of the induced electromotive force generated will also vary. Therefore, measuring the induced electromotive force of the receiver can effectively judge whether the ear is close to the receiver.

2 is a multimedia device 200 according to an embodiment of the present invention. The multimedia device 200 can be a typical mobile phone or telephone handset, and has a speaker 202 and a receiver 212 sharing the same back air cavity 210. The speaker 202 is externally connected to a first sound hole 204 for transmitting the sound emitted by the speaker 202. Similarly, the second speaker hole 214 is connected to the receiver 212 for transmitting the sound emitted by the receiver 212. The speaker 202 provides the function of the speakerphone, so the played source signal #A ' is louder. The gain of the sound source signal #A ' is provided by a gain amplifier 206, and the gain amplifier 206 determines the magnitude of the gain according to a control signal #ctrl.

In the multimedia device 200, the present invention provides a detector 220 coupled to the receiver 212 for detecting an induced electromotive force Sin generated by the receiver 212, and generating the control signal #ctrl according to the induced electromotive force Sin. The receiver 212 can be a conventional receiver that contains some of the basic components necessary for sounding, such as coils and sound films. The sound is transmitted through the immediately adjacent second sound hole 214. Since the receiver 212 does not provide a high gain value, the user must hold the ear close to the second sound hole 214 to hear the sound. When the receiver 212 is used to broadcast sound, the sound source signal is received from the endpoint P in the multimedia device 200. And when the receiver 212 When used as a sensor, the detector 220 also detects the induced electromotive force Sin generated in the receiver 212 from the end point P.

If the second sound hole 214 is not covered by foreign matter, the diaphragm and the coil in the receiver 212 can generate a large induced electromotive force. In contrast, if the second sound hole 214 is covered by the ear or other articles to form a confined space, the diaphragm in the receiver 212 is restricted by the air pressure to generate a lower induced electromotive force. Therefore, a threshold value #th can be determined according to actual experience, and the detector 220 compares the induced electromotive force Sin with the threshold value #th to determine the covering condition of the second sound hole 214. More specifically, the selection of the threshold value #th must be lower than the induced electromotive force generated when the second sound hole 214 is not covered, and higher than the inductance generated when the second sound hole 214 is covered. Electromotive force. In actual operation, as long as the induced electromotive force Sin is greater than the threshold value #th, the detector 220 can instruct the gain amplifier 206 to reduce the gain of the sound source signal #A through the control signal #ctrl to generate an adjusted sound source signal. #A ' .

More specifically, the detector 220 can be a comparator having a first input receiving the induced electromotive force Sin and a second input receiving the threshold #th, and the output comparison result is the control signal # Ctrl.

The receiver 212 may operate in a variety of situations. For example, the user is listening to the first source signal, such as music, through the receiver 212, and the speaker 202 suddenly receives an incoming call or is triggered by other events to play a second. Source signal, such as ringtones. At this time, the original playback state of the receiver 212 is first suspended, and the detector 220 is activated to detect the induced electromotive force Sin value of the receiver 212 to determine the playback volume of the incoming call ringtone.

On the other hand, the user may be listening to music through the speaker 202 in a broadcast manner, but suddenly needs to use the receiver 212 to answer the private call. At this time, the detector 220 can immediately determine whether the ear is close, and the speaker 202 is turned off, and the receiver 212 is turned on.

When detecting the occlusion state of the second sound hole 214, the multimedia device 200 can first play a preset calibration test sound through the horn 202, and the detector 220 receives the induced electromotive force Sin. However, the multimedia device 200 can also directly output the ringtone of the incoming call, so that the detector 220 can immediately determine whether the suppressed gain is needed. There are many variations on the actual operation and application of the multimedia device 200. The present invention does not limit the switching process between the speaker 202 and the receiver 212.

Usually, the speaker 202 or the receiver 212 will not be turned on at the same time, and only one will be turned on. For example, in the hands-free mode, only the speaker 202 needs to be turned on, and the receiver 212 does not need to be turned on. In contrast, in the handset mode, only the receiver 212 is turned on and the speaker 202 is off. Therefore, the multimedia device 200 can further include a selector 230 for determining to switch the sound source signal #A to the speaker 202 or the receiver 212.

In the present embodiment, since the detector 220 is connected to the input terminal P of the receiver 212, when the receiver 212 generates the induced electromotive force Sin, a diode 218 is required to prevent the induced electromotive force Sin from being poured back to the selector 230 or the previous stage circuit. . When the selector 230 selects to output the sound source signal #A to the receiver 212, it does not suppress the necessity of the speaker 202, so the detector 220 is in the off state. In contrast, when the selector 230 selects to output the sound source signal to the speaker 202, it is necessary to turn the detector 220 on. When the horn 202 plays the sound source signal #A ' , the sound film of the receiver 212 is resonated through the back air chamber 210, thereby driving the coil in the receiver 212 to generate the induced electromotive force Sin.

The circuit of the implementation of the detector 220 requires only a simple comparator, and the cost is lower than that of the conventional infrared sensor. The present invention does not limit the actual circuit design of the detector 220.

The multimedia device 200 of the present invention is particularly suitable for use in a mobile phone. The sound source signal for judging the cover state of the second sound hole 214 can directly use the ringtone of the caller or provide a calibration test tone.

Furthermore, the detector 220 can also use the same principle to determine the occlusion state of the first sound hole 204. If the multimedia device 200 is placed in a pocket, the first sound hole 204 and the second sound hole 214 are simultaneously covered. At this time, there is no need to protect the ear. On the contrary, it is necessary to increase the volume to let the user hear the ringtone of the incoming call. Therefore, only a single sound hole is covered, or both sound holes are covered, which is handled differently.

Figure 3 is a flow chart of the volume control method of the present invention. In step 301, the multimedia device 200 as shown in Fig. 2 is activated. In step 303, when an incoming call or a special event is triggered, the speaker 202 turns on and plays the sound source signal #A ' . In step 305, the detector 220 detects the induced electromotive force Sin generated by the receiver 212 through the endpoint P. In step 307, the detector 220 compares the induced electromotive force Sin with the threshold value #th, and the comparison result is output to the gain amplifier 206 as the control signal #ctrl. If the induced electromotive force Sin is smaller than the critical value #th, it means that the ear is not close, and no protection is required, so step 309 is performed. In contrast, if the induced electromotive force Sin is greater than the critical value #th, the gain is suppressed as shown in step 311 to protect the ear. In step 309, the gain amplifier 206 does not suppress the gain of the sound source signal #A, so that the sound source signal #A is directly played through the speaker 202. In step 311, the gain amplifier 206 suppresses the gain of the sound source signal #A according to the control signal #ctrl to generate a sound source signal #A ' with a lower volume or a silent state.

While the invention has been described above by way of a preferred embodiment, it is understood that the scope of the invention is not necessarily limited. In contrast, any modifications that are obvious to those skilled in the art or to those skilled in the art are within the scope of the invention. Therefore, the scope of patent claims must be interpreted in the broadest sense.

100‧‧‧Multimedia mobile phone

102‧‧‧Receiver

104‧‧‧Processor

106‧‧‧ sensor

108‧‧‧ sound hole

200‧‧‧Multimedia device

202‧‧‧ horn

204‧‧‧The first sound hole

206‧‧‧Gain Amplifier

210‧‧‧back air cavity

212‧‧‧Receiver

214‧‧‧Second sound hole

218‧‧‧ diode

220‧‧‧Detector

230‧‧‧Selector

1 is a conventional multimedia mobile phone 100; FIG. 2 is a multimedia device 200 according to an embodiment of the present invention; Figure 3 is a flow chart of the volume control method of the present invention.

200‧‧‧Multimedia device

202‧‧‧ horn

204‧‧‧The first sound hole

206‧‧‧Gain Amplifier

210‧‧‧back air cavity

212‧‧‧Receiver

214‧‧‧Second sound hole

218‧‧‧ diode

220‧‧‧Detector

230‧‧‧Selector

Claims (14)

A multimedia device includes: a gain amplifier for controlling the gain of an audio source signal according to a control signal; a first speaker coupled to the gain amplifier for playing the sound source signal; a second speaker, and the first The speaker shares a back air cavity, and is induced by the first speaker to generate an induced electromotive force; a detector coupled to the second speaker for detecting the induced electromotive force, and generating the control signal according to the induced electromotive force; When the induced electromotive force is greater than a threshold, the detector commands the gain amplifier to reduce the gain of the sound source signal through the control signal. The multimedia device of claim 1, wherein the detector is a comparator having a first input receiving the induced electromotive force, a second input receiving the threshold, and outputting a comparison result. This is the control signal. The multimedia device of claim 1, further comprising a selector for selectively selecting to output the sound source signal to the first speaker or the second speaker. The multimedia device of claim 3, further comprising a diode coupled between the second speaker and the selector to prevent the induced electromotive force from being fed back from the second speaker to the selector. The multimedia device of claim 3, wherein the detector is turned off when the selector selects to output the sound source signal to the second speaker. The multimedia device of claim 4, wherein the selection is When the selector selects to output the sound source signal to the gain amplifier, the detector is turned on. The multimedia device of claim 5, further comprising: a first sound hole connected to the first speaker for transmitting sound emitted by the first speaker; and a second sound hole connected to the a second speaker for transmitting sound from the second speaker. The multimedia device of claim 6, wherein when the first speaker plays the sound source signal, the sound film of the second speaker is resonated through the back air cavity, thereby driving the coil in the second speaker The induced electromotive force is generated. The multimedia device of claim 7, wherein the threshold value is that the second sound hole is covered by the user's ear or other object and the second speaker sound film and the voice coil have different vibration amplitudes according to the empirical value. The set induced electromotive force. The multimedia device of claim 1, wherein the multimedia device is a mobile phone; and wherein the first speaker is a speaker, the second speaker is a receiver, and the audio signal is a Caller ringtone or a calibration test tone. A volume control method is applied to a multimedia device, wherein the multimedia device includes a first speaker and a second speaker sharing a back air cavity, the volume control method includes: causing the first speaker to play an audio source signal; detecting the An induced electromotive force generated by the second speaker; If the induced electromotive force is greater than a threshold, the gain of the source signal is reduced. The volume control method of claim 10, further comprising selectively switching the sound source signal to the first speaker or the second speaker. The volume control method of claim 11, further comprising detecting the induced electromotive force of the second speaker when the second speaker is selected to output the sound source signal. The volume control method of claim 12, wherein the multimedia device further comprises: a first sound hole connected to the first speaker for transmitting the sound emitted by the first speaker; and a second sound a hole connected to the second speaker for transmitting the sound emitted by the second speaker; and the threshold value is lower than an induced electromotive force generated when the second sound hole is not covered, and the second sound hole is higher than the second sound hole The induced electromotive force generated when covering.