JP3761492B2 - Mobile phone and voice capturing method used therefor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a mobile phone and an audio capturing method used therefor, and more particularly to an audio capturing method in a mobile phone with a moving image shooting function.
[0002]
[Prior art]
In recent years, a mobile phone has realized a terminal to which a digital camera is added in order to take a still image, and an image taken by the digital camera is also transferred by e-mail. In addition, in this mobile phone, a terminal to which a moving image shooting function for enabling moving image shooting using a digital camera has appeared.
[0003]
The digital camera for photographing includes an example in which it is provided on the same side as the installation surface, an example in which it is provided on the back side of the installation surface, etc., based on the installation surface on which the microphone for voice input is installed. In either case, the sound that is captured during moving image shooting is collected by a microphone.
[0004]
[Problems to be solved by the invention]
However, in the conventional mobile phone described above, when the digital camera is provided on the back side of the microphone installation surface, the sound from the person to be photographed is collected from the back side of the microphone.
[0005]
The photographer's voice is collected from the front of the microphone in the same way as during a normal call, so the required frequency characteristics can be obtained, but if the voice is collected from the back of the microphone, use an omnidirectional microphone. Even so, there is a phenomenon that the microphone output level of 2 kHz or more deteriorates due to the influence of the mobile phone case on the back side of the microphone.
[0006]
For this reason, when the sound at the time of moving image shooting is reproduced from the mobile phone, the sound quality of the sound collected from the back side of the microphone may be degraded compared to the sound collected from the front side of the microphone.
[0007]
Therefore, the object of the present invention is to solve the above-mentioned problems and to correct the level deterioration of 2 kHz or more that occurs when taken from the back side of the microphone. It is an object of the present invention to provide a mobile phone capable of reducing a characteristic difference from the voice from the side and a voice capturing method used therefor.
[0008]
[Means for Solving the Problems]
The mobile phone according to the present invention is a mobile phone including a digital camera capable of shooting a moving image, and has a first and a second different in characteristics from means for making a key selection request for a voice capturing direction when the moving image shooting function is activated. A filter, and means for switching between the first and second filters in response to an external instruction for the key selection request.
[0009]
An audio capturing method according to the present invention is an audio capturing method for a mobile phone including a digital camera capable of capturing a moving image, the step of making a key selection request for an audio capturing direction when the moving image capturing function is activated, and the key selection request Switching between first and second filters having different characteristics according to an external instruction.
[0010]
That is, the mobile phone according to the present invention transmits a moving image in a terminal to which a moving image shooting function is added, depending on whether the direction of the audio to be captured is the front side of the microphone or the back side of the microphone. It is characterized by switching the speech filter and performing control to reduce deterioration of sound quality and transmission level.
[0011]
More specifically, in the mobile phone of the present invention, the key selection setting is performed during the moving image shooting operation, and whether the sound taken in during the moving image shooting is the sound from the front side of the microphone (the sound from the photographer) Select whether the sound is from the side (person to be photographed).
[0012]
As a result, in the case of audio from the front side of the microphone, a filter with the characteristic of removing the high frequency range used during normal calls is used, and in the case of audio from the back side of the microphone, attenuation in the high frequency band is reduced. By switching to a filter having a wideband filter characteristic, it becomes possible to correct a level deterioration of 2 kHz or more that occurs when taking in from the back side of the microphone, and the sound from the front side of the microphone and the sound from the back side of the microphone can be corrected. It is possible to reduce the characteristic difference.
[0013]
In addition, in the mobile phone of the present invention, the level of the captured audio is monitored in a certain time zone from the start of moving image shooting, and the level corresponding to the audio level when the level is captured from the microphone front side set in advance Compared with the level value, if it is equal to or lower than the reference level value, it is determined that the sound is from the back side of the microphone, and the filter is switched to a filter having a broadband filter characteristic with reduced attenuation of the high frequency band.
[0014]
As in the above case, this makes it possible to correct the level deterioration of 2 kHz or more that occurs when the sound is captured from the back side of the microphone, and the sound from the front side of the microphone and the back side of the microphone can be corrected. It is possible to reduce the characteristic difference from the voice.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a mobile phone according to an embodiment of the present invention. In FIG. 1, a mobile phone according to an embodiment of the present invention includes a microphone 1 for capturing sound when shooting a moving image, a microphone amplifier 2 for amplifying the output signal of the microphone 1, and an out-of-band audio band. The filter 4 that removes the frequency component, the filter control unit 3 that performs switching control of the filter 4 by selecting the shooting condition key 7, the voice data processing, the shot image processing from the digital camera 6, and the control to the shooting condition key 7 And a moving image shooting control unit 5 that performs the above.
[0016]
The filter 4 includes two filters (A) 4a and a filter (B) 4b having different characteristics, and the filter (A) 4a passes only within the voice band when performing a normal voice call, and other unnecessary. To remove unwanted frequency bands. That is, the filter (A) 4a is a filter having a characteristic of attenuating low and high frequencies like the A characteristic shown in FIG. The filter (B) 4b has a B characteristic shown in the figure. Compared with the filter (A) 4a, the attenuation in the high frequency band is reduced, and a broadband filter characteristic is realized.
[0017]
The shooting condition key 7 is a key for selecting the direction in which the voice is captured during moving image shooting, and selects whether the voice direction to be captured is from the front side of the microphone or the back side of the microphone by key operation. This operation is manually set by the carrier during the operation of the moving image shooting function, and is selected from “take in from the front side of the microphone” or “take in from the back side of the microphone”.
[0018]
FIG. 2 is a diagram showing an internal mounting state of a mobile phone according to an embodiment of the present invention. In FIG. 2, the mobile phone according to the embodiment of the present invention is opposite to the front liquid crystal monitor 24 because the photographer (carrier) generally takes a picture while looking at the front liquid crystal monitor 24. It is mounted on the back side of the microphone.
[0019]
On the other hand, the microphone 1 is mounted on the same surface as the front liquid crystal monitor 24 (on the opposite side to the digital camera 6, that is, on the front side of the microphone) in consideration of a telephone call function. Since the sound at the time of video recording is collected by the microphone 1, the sound spoken by the photographer (carrier) is collected from the front side of the microphone, but the sound from the subject to be photographed is collected from the back side of the microphone. Become. The shooting condition key 7 is a key for selecting the front side of the microphone, that is, capturing the voice of the user, and the back side of the microphone, that is, capturing the voice of the subject.
[0020]
The filter control unit 3 performs switching control so that the filter (A) 4a is selected when the sound is captured from the front side of the microphone and the filter (B) 4b is selected when the sound is captured from the back side of the microphone.
[0021]
The signal passing through the filter 4 is A / D (analog / digital) converted by the moving image shooting control unit 5 and stored as sound data. Thereafter, the moving image with sound is transmitted to the mobile phone of the other party as moving image reproduction or moving image mail.
[0022]
3 is a flowchart showing the operation of the mobile phone according to one embodiment of the present invention, FIG. 4 is a diagram showing the microphone characteristics of the mobile phone according to one embodiment of the present invention, and FIG. 5 is one embodiment of the present invention. FIG. 6 is a diagram showing the general transmission characteristics of a mobile phone according to an embodiment of the present invention. The operation of the mobile phone according to one embodiment of the present invention will be described with reference to FIGS.
[0023]
By operating the moving picture shooting function of the mobile phone according to one embodiment of the present invention, shooting is started by the digital camera 6 mounted on the back of the mobile phone (step S1 in FIG. 3). In addition, the video being taken can be monitored by the wearer with the front liquid crystal monitor 24, and a voice capturing operation is performed with the microphone 1 mounted on the same surface as the front liquid crystal monitor 24.
[0024]
Since sound at the time of moving image shooting is collected by the microphone 1, in this embodiment, the carrier (photographer) selects in advance whether to collect the sound from the front side of the microphone or from the back side of the microphone. The photographing condition key 7 is provided, and setting is performed by key operation on the front liquid crystal monitor 24 (step S2 in FIG. 3).
[0025]
The audio signal collected by the microphone 1 is amplified in a wide band by the microphone amplifier 2 and sent to the filter control unit 3. The filter control unit 3 selects the filter (A) 4a in the filter 4 and the sound from the person to be photographed when capturing the photographer's voice according to the result of the shooting condition key 7 set at the start of moving image shooting. Control to select the filter (B) 4b in the filter 4 is performed.
[0026]
If the user wants to capture his / her voice while shooting a moving image, the shooting condition key 7 requested to be selected from the mobile phone during the moving image shooting operation is determined to be “capture from the front side of the microphone”.
[0027]
The filter control unit 3 recognizes from the setting information of the photographing condition key 7 that the sound is taken in from the front side of the microphone, and controls the switching of the filter 4 so as to pass the filter (A) 4a (step in FIG. 3). S3, S4).
[0028]
The filter (A) 4a attenuates low and high frequencies such as the A characteristic shown in FIG. 5 for the purpose of passing only the voice band for normal voice calls and removing other unnecessary frequency bands. This is a filter having the characteristic of
[0029]
The transmission characteristics of the microphone 1 are shown in FIG. This characteristic is a microphone output level characteristic when the microphone 1 is mounted on the case (lower) 23 of the mobile phone. When a sound signal is input from the front side of the microphone, the A characteristic shown in FIG. 4 is obtained.
[0030]
The signal amplified by the microphone amplifier 2 passes through the filter (A) 4a switched by the filter control unit 3 (step S5 in FIG. 3). As a result, the sound characteristic input to the moving image shooting control unit 5 is finally a characteristic obtained by combining the characteristic of the filter (A) 4a and the A characteristic of the microphone 1, that is, the frequency according to the A characteristic shown in FIG. The characteristic voice is stored at the time of moving image shooting and becomes the sound data characteristic attached at the time of moving image reproduction or moving image mail (steps S6 and S7 in FIG. 3).
[0031]
On the other hand, when “capturing from the back side of the microphone” is selected by the shooting condition key 7, the filter control unit 3 recognizes that the voice is being captured from the back side of the microphone by the setting information of the shooting condition key 7. Switching control of the filter 4 is performed so as to pass the filter (B) 4b (steps S3 and S8 in FIG. 3).
[0032]
Microphone characteristics from the back side of the microphone are as shown by B characteristics shown in FIG. In general, when sound data is input from the back side of the microphone, the microphone output level is lowered as compared with the input of sound data from the front side of the microphone, particularly at a frequency of 2 kHz or more, as shown by the B characteristic.
[0033]
The filter (B) 4b has a filter characteristic of B characteristics shown in FIG. 5, and the filter (A) 4a shown in FIG. 5 is corrected so as to correct the output level deterioration of 2 kHz or more due to sound data input from the back side of the microphone. Compared with the A characteristic shown in Fig. 5, the filter characteristic of the wide band with reduced cut in the high frequency band is provided.
[0034]
The signal amplified in a wide band by the microphone amplifier 2 passes through the filter (B) 4b switched by the filter control unit 3 (step S10 in FIG. 3). As a result, the sound characteristic input to the moving image shooting control unit 5 is finally the sound having the frequency characteristic according to the B characteristic shown in FIG. 6 in which the characteristic of the filter (B) 4b and the B characteristic of the microphone 1 are combined. Is stored at the time of moving image shooting and becomes the sound data characteristic attached at the time of moving image reproduction or moving image mail (steps S6 and S7 in FIG. 3).
[0035]
According to the above, correction is made with the filter characteristic that passes the transmission level deterioration at 2 kHz or more that occurs at the time of capturing the voice from the back side of the microphone, and the characteristic difference between the voice from the front side of the microphone and the voice from the back side of the microphone is reduced. be able to.
[0036]
FIG. 7 is a block diagram showing the configuration of a mobile phone according to another embodiment of the present invention. 7, another embodiment of the present invention is the same as that shown in FIG. 1 except that a transmission level detection unit 8, a comparison unit 9, and a reference transmission level value storage unit 10 are provided instead of the photographing condition key 7. The configuration is the same as that of one embodiment of the invention, and the same reference numerals are given to the same components.
[0037]
In the mobile phone according to the embodiment of the present invention, in response to a setting request at the time of moving image shooting operation, “take in from the front side of the microphone” and “take in from the back side of the microphone” are performed by the key setting operation of the shooting condition key 7. By making selections and switching the subsequent pass filter, sound characteristic deterioration from the back of the microphone is corrected. On the other hand, in this embodiment, the sound level at the time of moving image shooting is monitored, and the comparison is made with respect to a preset reference level, so that the subsequent stage filter is switched to perform sound correction.
[0038]
The audio signal collected by the microphone 1 is amplified in a wide band by the microphone amplifier 2 and sent to the filter 4. The filter 4 includes two filters (A) 4a and a filter (B) 4b having different characteristics as in the embodiment of the present invention, and controls to use the file (A) at the start of moving image shooting. .
[0039]
The transmission level detection unit 8 detects the level of audio data that has passed through the filter (A) 4a at a fixed timing. The comparison unit 9 compares the data from the transmission level detection unit 8 with a reference level value preset in the reference transmission level value storage unit 10 and sends the comparison result to the filter control unit 3. The filter control unit 3 performs control to switch the subsequent filter 4 in accordance with information from the comparison unit 9.
[0040]
The reference level value set in the reference transmission level value storage unit 10 is set to a value equivalent to the transmission level value collected when the user (photographer) inputs sound from the front side of the microphone. Keep it. Usually, the transmission level captured from the back side of the microphone is, as shown by the B characteristic in FIG. 4, due to reasons such as deterioration of the level particularly at 2 kHz or higher, and the distance between the subject and the mobile phone being separated. It is considered that the voice level spoken by the user (photographer) from the front side of the microphone is lower than the transmission level at which the microphone collects sound. Therefore, it can be easily predicted that the transmission level from the back side of the microphone will be lower than the set reference level value.
[0041]
Thereby, when the filter control unit 3 determines that the comparison unit 9 determines that the level is equal to or higher than the reference level value, the filter control unit 3 selects the filter (A) 4a based on the voice capturing state from the front side of the microphone and determines that the level is equal to or lower than the reference level value Then, it is determined that the voice is being taken in from the back side of the microphone, and control for selecting the filter (B) 4b is performed.
[0042]
FIG. 8 is a flowchart showing the operation of a mobile phone according to another embodiment of the present invention, and FIG. 9 is a diagram showing an output waveform of the transmission level detector 8 of FIG. The operation of the mobile phone according to another embodiment of the present invention will be described with reference to FIGS.
[0043]
When the moving picture shooting function of the mobile phone according to another embodiment of the present invention starts to operate (step S11 in FIG. 8), sound is collected by the microphone 1 (step S12 in FIG. 8). The sound collected by the microphone 1 is amplified by the microphone amplifier 2 (step S13 in FIG. 8), passes through the initially set filter (A) 4a (step S14 in FIG. 8), and is recorded in the moving image shooting control unit 5. Audio signal A / D conversion and storage are performed.
[0044]
The transmission level detection unit 8 monitors the signal input to the moving image shooting control unit 5 (step S15 in FIG. 8), and the comparison unit 9 compares it with a preset reference transmission level value (step S16 in FIG. 8). .
[0045]
When the output waveform of the transmission level detection unit 8 as shown in FIG. 9 is detected, the comparison unit 9 detects the output waveform of the transmission level detection unit 8 within the time T (sec) after starting the moving image shooting function. Comparison with the reference level value set in the reference transmission level value storage unit 10 is performed. In this case, since a level equal to or higher than the reference level value is not detected during T (sec), the comparison unit 9 determines that the level is equal to or lower than the reference level value, and performs control to switch the filter control unit 3 to the filter (B) 4b (FIG. 8 step S21).
[0046]
The reference level value is set to be equivalent to the level value collected when the user (photographer) inputs sound from the front side of the microphone. It can be assumed that the sound is captured from the back side of the microphone.
[0047]
As described in the embodiment of the present invention, the filter (B) 4b has a filter characteristic of B characteristic shown in FIG. 5, and an output level degradation of 2 kHz or more due to sound data input from the back side of the microphone. Compared with the A characteristic shown in FIG. 5 of the filter (A) 4a, the filter (A) 4a has a broadband filter characteristic in which the cut in the high frequency band is reduced.
[0048]
The sound characteristic input to the moving image shooting control unit 5 is finally the sound of the frequency characteristic according to the B characteristic shown in FIG. 6 in which the characteristic of the filter (B) 4b and the B characteristic of the microphone 1 are combined. It is sometimes stored and becomes a sound data characteristic attached at the time of moving image reproduction or moving image mail (steps S22, S19, S20 in FIG. 8).
[0049]
In addition, when a transmission level equal to or higher than the reference level value is detected within T (sec), it can be predicted that the voice is captured from the front side of the microphone, so the filter control unit 3 selects the filter (A). (Step S17 in FIG. 8), the audio characteristic input to the moving image shooting control unit 5 finally follows the A characteristic shown in FIG. 6, which combines the characteristic of the filter (A) 4a and the A characteristic of the microphone 1. Sound with frequency characteristics is stored at the time of moving image shooting, and becomes sound data characteristics attached at the time of moving image reproduction or moving image mail (steps S18 to S20 in FIG. 8).
[0050]
According to the above, correction is made with the filter characteristic that passes the transmission level deterioration at 2 kHz or more that occurs at the time of capturing the voice from the back side of the microphone, and the characteristic difference between the voice from the front side of the microphone and the voice from the back side of the microphone is reduced. be able to.
[0051]
As described above, according to the present invention, the key selection setting is performed during the moving image shooting operation, and whether the sound captured during the moving image shooting is the sound from the front side of the microphone (sound from the photographer) or the sound from the back side of the microphone (shooting). In the case of the sound from the back side of the microphone using the filter (A) 4a having a characteristic in which the high frequency range used in normal calls is removed in the case of the sound from the front side of the microphone By switching to the filter (B) 4b having a wideband filter characteristic with reduced attenuation in the high-frequency band, it is possible to correct a level deterioration of 2 kHz or more that occurs when the microphone is taken in from the back side of the microphone, and to correct the front side of the microphone. The characteristic difference between the sound from the microphone and the sound from the back side of the microphone can be reduced.
[0052]
Further, in the present invention, the level of the captured audio is monitored in a certain time zone from the start of moving image shooting, and compared with a reference level value corresponding to the audio level when captured from the front side of the microphone set in advance. When the sound is taken from the back side of the microphone by switching to the filter (B) 4b having a wideband filter characteristic with reduced attenuation in the high frequency band, when the sound is determined to be from the back side of the microphone when the reference level value is below Therefore, it is possible to correct the level deterioration of 2 kHz or more that occurs in the microphone, and to reduce the characteristic difference between the sound from the front side of the microphone and the sound from the back side of the microphone.
[0053]
【The invention's effect】
As described above, according to the present invention, in a mobile phone including a digital camera capable of shooting a moving image, a key selection request for the voice capturing direction is made when the moving image shooting function is activated, By switching between the different first and second filters, it is possible to correct the level deterioration of 2 kHz or more that occurs when taking in from the back side of the microphone, and from the back side of the microphone and the sound from the front side of the microphone The effect that the difference in characteristics from the voice can be reduced is obtained.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a mobile phone according to an embodiment of the present invention.
FIG. 2 is a diagram showing an internal mounting state of a mobile phone according to an embodiment of the present invention.
FIG. 3 is a flowchart showing an operation of the mobile phone according to the embodiment of the present invention.
FIG. 4 is a diagram illustrating microphone characteristics of a mobile phone according to an embodiment of the present invention.
FIG. 5 is a diagram illustrating filter characteristics of a mobile phone according to an embodiment of the present invention.
FIG. 6 is a diagram illustrating a general transmission characteristic of a mobile phone according to an embodiment of the present invention.
FIG. 7 is a block diagram showing a configuration of a mobile phone according to another embodiment of the present invention.
FIG. 8 is a flowchart showing an operation of a mobile phone according to another embodiment of the present invention.
9 is a diagram showing an output waveform of a transmission level detection unit in FIG. 7;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Microphone 2 Microphone amplifier 3 Filter control part 4 Filter 4a Filter A
4b Filter B
5 Video shooting control unit 6 Digital camera 7 Shooting condition key 8 Transmission level detection unit 9 Comparison unit 10 Reference transmission level value storage unit 21 Antenna 22 Mobile phone case (upper)
23 Mobile phone case (bottom)
24 Front LCD monitor

Claims (8)

  A mobile phone including a digital camera capable of shooting a moving image, wherein means for making a key selection request for a voice capturing direction when a moving image shooting function is activated, first and second filters having different characteristics, and the key selection request And a means for switching the first and second filters in response to an external instruction to the mobile phone. The first filter is a filter having a characteristic that the level deterioration in the high sound range is large,
The second filter is a filter having a characteristic of low level deterioration in a high sound range, and the second filter is selected in the case of capturing sound from the back side of the microphone in response to an external instruction in response to the key selection request. The mobile phone according to claim 1, characterized in that: A mobile phone including a digital camera capable of shooting a movie,
Means for monitoring a certain transmission level from the start of moving image shooting operation, comparison means for comparing the monitoring result with a preset reference level value, first and second filters having different characteristics, and the comparison Means for switching the first and second filters according to a comparison result of the means,
The mobile phone according to claim 1, wherein the reference level value is set to a transmission level corresponding to a voice level captured from the front side of the microphone and is equal to or higher than a voice level captured from the rear side of the microphone . The first filter is a filter having a characteristic that the level deterioration in the high sound range is large,
The second filter is a filter having a characteristic in which a level deterioration in a high sound range is small, and the first filter is selected when a comparison result of the comparison unit is a level larger than the reference level value, and the reference level value 4. The mobile phone according to claim 3 , wherein the second filter is selected at a lower level.   An audio capturing method for a mobile phone including a digital camera capable of capturing a moving image, the step of making a key selection request for a sound capturing direction when the moving image capturing function is activated, And switching between different first and second filters. The first filter is a filter having a characteristic that the level deterioration in the high sound range is large,
The second filter is a filter having a characteristic of low level deterioration in a high sound range, and the second filter is selected in the case of capturing sound from the back side of the microphone in response to an external instruction in response to the key selection request. 6. A voice capturing method according to claim 5, wherein An audio capturing method for a mobile phone including a digital camera capable of shooting a movie,
A step of monitoring a certain transmission level from the start of the moving image shooting operation, a step of comparing the monitoring result with a preset reference level value, and a first and a second having different characteristics depending on the comparison result of the comparison means possess the step of switching the second filter,
The reference level value is set to a transmission level corresponding to an audio level acquired from the front side of the microphone, and is equal to or higher than an audio level acquired from the rear side of the microphone . The first filter is a filter having a characteristic that the level deterioration in the high sound range is large,
The second filter is a filter having a characteristic in which a level deterioration in a high sound range is small, and the first filter is selected when a comparison result of the comparison unit is a level larger than the reference level value, and the reference level value 8. The voice capturing method according to claim 7 , wherein the second filter is selected at a lower level.

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