JP3576915B2 - Mobile phone equipment - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a mobile phone device, and more particularly to a mobile phone device provided with a microphone that can reduce the influence of ambient noise.
[0002]
[Prior art]
In an ordinary mobile phone device, an electrolet microphone is mounted and used at a lower end of a main body or a lower side of a flapper attached to the main body.
With the miniaturization of mobile telephone devices, these microphones have also been miniaturized.
In recent years, optical microphone elements have attracted attention as small microphone elements, and in particular, those using a vertical cavity surface emitting laser (hereinafter, referred to as VCSEL) as light emitting elements can achieve further miniaturization.
Further, in the use of a normal mobile phone device, the relationship between the microphone and the mouth of the speaker is close to each other. In some cases, the distance between the telephone device and the speaker increases, and thus the distance between the speaker and the microphone increases.
[0003]
[Problems to be solved by the invention]
However, in the conventional mobile phone device, even when such a mobile phone device is used away from the mouth of a caller, no special measures are taken for the built-in microphone.
Therefore, when using the portable telephone device away from the speaker, there is a problem that it is difficult to sufficiently collect voice due to the influence of ambient noise.
In addition, there is another problem that the sensitivity is reduced because the microphone moves away from the mouth when performing operations such as transmission and reception while watching the display on the display.
The present invention solves the above-described problem, and does not cause a decrease in sensitivity even when the built-in microphone is used at a distance from the speaker's mouth, and furthermore minimizes noise contamination as much as possible. It is an object to provide a mobile phone device using a microphone element.
[0004]
[Means for Solving the Problems]
In order to achieve the above object, a mobile phone device according to the present invention has a first usage state in which the mobile phone device is used in close contact with the face and a second usage state in which the mobile phone device is used away from the face. A sensor for detecting the separation distance from the device is attached to the device, and a vertical cavity surface emitting laser light emitting device having a light emission intensity distribution substantially uniform in a concentric circle is arranged as a built-in microphone to receive the light emitted from the light emitting device. A substrate on which the light-receiving element is disposed, and installed substantially parallel to and close to a position facing the substrate, vibrates by sound pressure, reflects light from the light-emitting element, and radiates the light to the light-receiving element. A diaphragm, a light source driving circuit that supplies a driving current to the light emitting element, and a negative feedback circuit that supplies a part of a signal output from the light receiving element to the light source driving circuit as a negative feedback signal. Using light microphone for Bei, controls the directional characteristics of the optical microphone by changing the magnitude of the negative feedback signal by a sensor signal indicative of the distance.
[0005]
Further, the mobile phone device of the present invention is a mobile phone device having a first use state in which the mobile phone device is used in close contact with the face and a second use state in which the mobile phone device is used while being separated from the face. A proximity sensor that outputs a detection signal that is turned off at one time and turned on at the time of the second use state is attached to the device, and as a built-in microphone, a vertical cavity surface emission type in which the emission intensity distribution is substantially uniform concentrically. A laser light-emitting element is arranged, and a substrate on which a light-receiving element for receiving radiation light of the light-emitting element is arranged, is installed substantially parallel to and close to a position facing the substrate, and vibrates by sound pressure. A diaphragm that reflects light from the light emitting element and emits the light to the light receiving element, a light source driving circuit that supplies a driving current to the light emitting element, and a part of a signal output from the light receiving element. A directional characteristic of the optical microphone is controlled by switching the magnitude of the negative feedback signal in two stages in response to the detection signal using an optical microphone having a negative feedback circuit that supplies the signal to the light source driving circuit. I do.
[0006]
BEST MODE FOR CARRYING OUT THE INVENTION
In the portable telephone device of the present invention, an optical microphone using a VCSEL is used as a built-in microphone.
The optical microphone can change directional characteristics and can form a sharp directional beam pattern in a predetermined direction.
For this reason, even if the distance between the microphone and the mouth is large, a decrease in sensitivity can be prevented, and noise contamination can be eliminated.
First, prior to the description of the embodiment of the mobile phone device of the present invention, the basic principle and structure of an optical microphone using a VCSEL used in the present invention will be described.
[0007]
FIG. 11 is a diagram showing the structure of the head portion of the optical microphone element 50.
A diaphragm 2 that vibrates when subjected to sound waves is stretched over the microphone head (container) 1. The surface 2a on the side to which the sound wave strikes is exposed to the outside.
Accordingly, the sound wave 7 reaches the surface 2a and vibrates the diaphragm 2.
FIG. 11A shows a cross-sectional shape. An electronic circuit board 12 is installed on the bottom surface 8 of the container 1, and a substrate 9 on which a light emitting element and a light receiving element are arranged is mounted on the substrate 12. The attachment can also be performed by electrically connecting the substrate 9 and the substrate 12 by, for example, flip chip bonding. If the bottom surface 8 is formed of a semiconductor substrate such as silicon, an electronic circuit can be formed thereon, and the electronic circuit substrate 12 can be omitted. In the example shown in FIG. 8, a vertical cavity surface emitting laser diode LD is used as a light emitting element, and a photodiode PD is used as a light receiving element. A circular surface emitting laser diode LD is arranged at the center of the substrate 9, and the light receiving elements PD are arranged concentrically around the surface emitting laser diode LD.
[0008]
FIG. 11B is an enlarged plan view showing a light emitting / receiving section of the substrate 9 on which the light emitting / receiving elements shown by dotted lines in FIG. 11A are mounted.
As shown in the figure, a circular light emitting element LD is arranged at the center, and light receiving elements PD1, PD2,... PDn are arranged concentrically so as to surround the light emitting element LD. Note that a vertical cavity surface emitting laser can be used as the light emitting element LD used here.
The light emitting element LD and the light receiving element PD can be simultaneously manufactured on a gallium arsenide wafer by a semiconductor manufacturing process.
Therefore, since the alignment accuracy between the light emitting element LD and the light receiving element PD is determined by the accuracy of the mask used in the semiconductor manufacturing process, the alignment accuracy can be made 1 μm or less, and the conventional light receiving and emitting element of the optical microphone element can be used. It can be realized with a high accuracy of 1/100 or less as compared with the alignment accuracy.
[0009]
In general, a vertical cavity surface emitting type light emitting device has a characteristic in which a light emission intensity distribution is concentric and almost uniform. Therefore, the radiated light emitted from the light emitting element LD installed at the center toward the diaphragm 2 at a predetermined angle is reflected concentrically with the same intensity, and the diaphragm 2 is vibrated by receiving the sound wave 7. As a result, the reflection angle changes and the light reaches the light receiving element PD concentrically.
Accordingly, the vibration displacement of the diaphragm 2 can be detected by detecting a change in the amount of received light of the light receiving elements PD1 to PDn arranged concentrically. As a result, the strength of the incident sound wave 7 can be detected, so that it can be used as an optical microphone element.
An electrode 11 is formed for driving the light emitting element LD and the light receiving element PD or detecting the amount of incident light.
[0010]
Next, a vertical cavity surface emitting laser (hereinafter, referred to as VCSEL) which is a light emitting element used in the present invention will be described.
FIG. 12 shows the emission intensity distribution of the VCSEL. As shown in the figure, the emission intensity distribution is given as a Gaussian distribution with respect to the inside of the nucleus.
The emission intensity distribution P0 (θ) is represented by the following equation (1).
(Equation 1)
Po (θ) = exp (−α ² θ ² ) (1)
θ: angular displacement from a vertical line on the light emitting surface (unit radian)
α: Coefficient for defining the emission divergence angle (originally simplified in calculation of “1 / α ² ”)
[0011]
When the calculation of the light emission distribution coefficient α is calculated for a one-dimensional case, it is expressed as in equation (2).
(Equation 2)
α ² = − [ln (h)] / (FAHM / 2) ² (2)
h: 1 at the relative intensity vertical given by actually measuring the laser emission distribution. Half value = 0.5.1 / e = 0.3183.1 / e2 = 0.135335.
FAHM: Normally, the manufacturer provides a full width at half maximum (FAHM) value.
If h = 0.5, FAHM = 9 degrees (with angle), rad (9/2) = 0.07854
α ² = − [(ln (0.5)] / (0.07854) ² = 112.369
Then, using this to calculate the emission intensity distribution for the specified azimuth, the distribution as shown in FIG. 12 is obtained.
[0012]
FIG. 13 is a diagram in a case where the emission intensity distribution is calculated and illustrated in two dimensions.
In this case, the two-dimensional emission intensity distribution P0 (θ) is given by equation (3).
(Equation 3)
Po (θ) = exp (−α ² θ ² ) · exp (−β ² ψ ² ) (3)
The distribution calculation coefficients α and β are calculated for the θ and ψ directions in the same manner. The light emission distribution coefficient α is given by equation (4), and the light emission distribution coefficient β is given by equation (5).
(Equation 4)
α ² = − [ln (h)] / (FAHM / 2) ² (4)
If h = 0.5 and FAHM = 9 degrees, rad (9/2) = 0.07854
α ² = − [(ln (0.5)] / (0.07854) ² = 112.369
(Equation 5)
β ² = − [ln (h)] / (FAHM / 2) ² (5)
If h = 0.5 and FAHM = 9 degrees, rad (9/2) = 0.07854
β ² = − [(ln (0.5)] / (0.07854) ² = 112.369
[0013]
As is apparent from the two-dimensional emission intensity distribution obtained in this way, in the vertical cavity surface emitting laser, the intensity distribution of the light emitting element is almost concentrically uniform.
Therefore, in order to efficiently receive the laser light as the displacement (displacement) of the diaphragm 2, it is optimal to arrange the light receiving elements concentrically. Then, the differential signal of the signal detected by the light receiving elements belonging to different concentric circles arranged concentrically becomes a signal giving a change in sound pressure.
Here, in order to limit or select the dynamic range of the received signal, it becomes possible by providing two or more light receiving elements concentrically.
However, the optical microphone shown in FIG. 11 cannot expect much noise reduction effect.
That is, the diaphragm 2 also vibrates due to the noise that reaches the diaphragm 2, and this is superimposed on the vibration of the normal sound wave 7 as a noise signal.
[0014]
An optical microphone having a structure as shown in FIG. 3 has been known as an optical microphone which has reduced the influence of this noise and has further improved the noise reduction effect.
In the structure shown in FIG. 3, the vibrating plate 2 vibrated by the sound wave 7 is stretched substantially at the center of the container 1. A first opening 15 and a second opening 16 are provided on both sides of the container 1 so as to be symmetrical with respect to the diaphragm 2.
With such a configuration, the sound wave 7 enters the container 1 from any of the openings 15 and 16 and vibrates the diaphragm 2.
Note that FIG. 3 shows a structure in which the light emitting element LD and the light receiving element PD are separated for convenience of explanation. However, in actuality, FIG. 11 shows that the light emitting element LD and the light receiving element PD are integrally formed on the substrate 9. The structure shown in Fig. 1 is used.
[0015]
In the optical microphone element 50 shown in FIG. 3, when the amplitude and the phase of the sound wave entering from the first opening 15 and the sound wave entering from the second opening 16 are equal, these two sound waves are applied to both surfaces of the diaphragm 2. The vibration plate 2 is not vibrated by canceling each other in 2a and 2b.
It is known that when two microphone elements having the same receiving sensitivity are arranged close to each other and a sound wave generated at a long distance is received, the two microphone elements detect the incoming sound waves equally.
[0016]
Generally, sound waves originate from the mouth of a person at a short distance from the microphone element, ie, sound is generated at a short distance from the microphone element. This short-range person's voice has a spherical field characteristic as shown by the circular curve.
On the other hand, sound waves generated at a long distance, for example, due to noise and acoustics have characteristics of a plane field.
The sound intensity of a spherical wave is approximately the same along its sphere or envelope and varies along the radius of the sphere, but for a plane wave the sound intensity is approximately the same at all points in the plane.
[0017]
Therefore, since the optical microphone element as shown in FIG. 3 can be considered to be a combination of two microphone elements, when it is placed in a far field, the first opening 15 and the second opening 16 As a result, sound waves having substantially the same amplitude and phase characteristics arrive at the diaphragm 2 and cancel each other out as described above, thereby reducing the effect.
On the other hand, a sound wave from the near field is incident nonuniformly through the first opening 15 or the second opening 16 so that the vibration plate 2 is vibrated and extracted as a signal from the light receiving element PD. In this way, an optical microphone element capable of further reducing the influence of noise is obtained by the structure of FIG.
[0018]
FIG. 6 is a diagram showing a directivity pattern of the optical microphone element shown in FIGS.
11A shows the directivity pattern of the optical microphone element 50 shown in FIG. 11, and has a substantially circular directivity having a maximum sensitivity in a direction perpendicular to the diaphragm 2 toward the opening (left side in the figure). Have a sexual pattern.
(B) shows the directivity pattern of the optical microphone element 50 shown in FIG. 3, which has a substantially 8-shaped directivity pattern having maximum sensitivity in both directions of the openings 15 and 16.
Here, the directivity pattern of the optical microphone element 50 shown in FIGS. 11 and 3 is changed so as to extend in the axial direction showing the maximum sensitivity as shown in FIG. 2 or 5, or to narrow down in the direction perpendicular to the axis. be able to.
[0019]
In order to change the directivity pattern as described above, a part of the detection output from the light receiving element PD is negatively fed back (negative feedback) to the light source driving circuit that drives the light emitting element LD using a negative feedback circuit. Good. FIG. 4 is a diagram showing a schematic configuration of an optical microphone device using a feedback circuit 100 for changing a beam pattern as shown in FIG. 2 or FIG.
The output from the light receiving element PD is taken out through the filter circuit 18 and amplified by the amplifier 19 to become the microphone output.
The filter circuit 18 is used to extract only a signal component in a desired frequency range.
[0020]
Here, in the optical microphone device shown in FIG. 4, a predetermined current is supplied to a light emitting element LD through a negative feedback (negative feedback: NFB) circuit 100 to supply a part of an output signal taken out of the light receiving element PD. The light source driving circuit 13 that drives the light emitting element LD is configured to be supplied as a negative feedback signal.
The negative feedback circuit 100 includes a small signal amplifier circuit 10, a filter circuit 15 for extracting only a signal component in a desired frequency range from its output, and a comparator 16.
A reference power supply 14 serving as a reference voltage is connected to a non-inverting input terminal of the comparator 16.
The signal extracted through the filter circuit 15 is supplied to the inverting input terminal of the comparator 16.
[0021]
With this configuration, the comparator 16 outputs a lower output level as the output of the filter circuit 15 increases, whereby the light source drive circuit 13 operates to reduce the current supplied to the light emitting element LD.
Here, the small signal amplifying circuit 10 amplifies the signal only when the input signal level is lower than a predetermined level, and does not amplify a signal higher than a certain level.
Therefore, when the input signal level is equal to or higher than a certain level, the output signal level does not change and the amplification (gain) becomes zero. When the input signal is lower than a predetermined signal level, the signal is amplified so that the smaller the signal level, the larger the amplification.
Further, the rate of increase of the output signal with respect to the input signal increases as the input signal level decreases.
Here, since the output from the light receiving element PD is proportional to the received sound volume, the output of the small signal amplifying circuit 10 is amplified and output as the volume becomes smaller.
[0022]
Since this output is input to the inverting input terminal of the comparator 16 via the filter circuit 15, the output level of the comparator 16 decreases as the volume decreases.
As a result, the current supplied to the light emitting element LD operates so that the light output of the light emitting element LD decreases as the volume decreases.
That is, the lower the volume, the lower the sensitivity of the microphone.
Further, since a signal of a predetermined level or higher is not amplified, the light output is not limited at the signal level.
Therefore, the sensitivity of the microphone does not decrease.
For sounds that come from the axial direction perpendicular to the diaphragm and that do not cause a decrease in microphone sensitivity, if the sound is shifted from the axial direction, the sensitivity will follow the original directivity pattern curve. It gradually decreases.
When the level falls below a certain level, the small signal amplifier circuit 10 has an amplification degree, and the supply current control of the light source drive circuit 13 works to further reduce the sensitivity of the microphone.
As a result, in the optical microphone device having the negative feedback circuit 100, as shown in FIG. 2 or FIG. 5, the pattern of the directional beam is narrower than the directional pattern of the sensitivity.
[0023]
2 and 5 show a change in the directivity pattern due to the change in the amount of negative feedback.
(A) shows the directivity pattern when no negative feedback is applied, and in this case, the directivity pattern is substantially circular.
Next, the directivity patterns when negative feedback is applied are shown in (B) and (C).
In the case of (B), the amount of negative feedback is small, and in the case of (C), the amount of negative feedback is large. By changing the amplification degree of the small signal amplifier circuit 10 in this way, the amount of negative feedback is changed to extend the directivity pattern of sensitivity in the axial direction of maximum sensitivity or to narrow down in the direction orthogonal to the axis. be able to.
In this manner, the directional characteristics of the sensitivity of the optical microphone can be changed.
In the sound pickup device according to the present invention, the directivity of the selected microphone is changed by using an optical microphone of a very small VCSEL that can change the beam pattern of the directivity.
[0024]
Next, an embodiment of the portable telephone device of the present invention will be described.
FIG. 7 is a diagram showing a schematic configuration of a conventional mobile phone device. A mobile phone device 200 includes a speaker 201 at an upper end of a main body and a microphone 204 at a lower end, and inputs telephone number and fax information on its surface. Key 203 and a display unit 202 are provided.
FIG. 8 is a diagram showing an example of a mobile phone device according to the present invention, in which the above-described optical microphone element 50 is used instead of the conventional microphone 204.
Further, a proximity sensor 55 for detecting the positions of the microphone element 50 and the speaker of the mobile phone device 200 is provided at a predetermined position of the mobile phone device 200.
[0025]
FIG. 9 is a diagram showing a method of using the mobile phone device according to the present invention. In a normal usage method, the mobile phone device 200 is used in close contact with a speaker, and in this state, the proximity sensor 55 is used to connect the speaker and the mobile phone. It recognizes that the distance is close.
When the mobile phone device 200 is operated away from the speaker, for example, when an operation for transmitting and receiving is performed while watching the display on the display 202, the mobile phone device 200 is different from the use state illustrated in FIG. Placed away from speaker.
In this case, the proximity sensor 55 recognizes that the distance between the speaker and the mobile phone device 200 is a long distance.
Since a specific method of distance recognition by the proximity sensor 55 is well known, a detailed description thereof will be omitted.
[0026]
In the present invention, the proximity sensor 55 attached to the mobile phone body recognizes the distance between the speaker and the mobile phone device, and changes the magnitude of the negative feedback signal of the optical microphone element 50 based on the recognition result. Thus, the directional characteristics of the optical microphone element 50 are controlled.
FIG. 1 is a diagram showing a circuit for changing the directivity of a microphone in a mobile phone device of the present invention.
The amount of negative feedback of the negative feedback circuit 100 is changed by a sensor signal from the proximity sensor 55.
That is, when the proximity sensor 55 recognizes that the distance between the mobile phone device 200 and the speaker's mouth is far, the negative feedback amount of the negative feedback circuit 100 is increased by the output signal of the proximity sensor 55, and the The directivity pattern of the microphone element 50 is narrowed down and sharpened so that sound from the mouth of the speaker is received with high sensitivity.
As described above, the amount of negative feedback of the negative feedback circuit 100 can be adjusted by increasing the degree of amplification of the small signal amplifier circuit 10 shown in FIG.
[0027]
FIG. 10 shows another circuit used in the portable telephone device of the present invention. In this case, a switch 56 for connecting or disconnecting the negative feedback circuit 100 based on the output of the proximity sensor 55 is provided.
When the proximity sensor 55 recognizes that the speaker is close to the speaker, the switch 56 is turned off and the negative feedback by the negative feedback circuit 100 is stopped. As a result, a normal wave receiving state is set.
When the proximity sensor 55 determines that the distance is long, the switch 56 is turned on.
Then, since the negative feedback circuit 100 operates, the directivity pattern of the optical microphone element 50 becomes sharp as shown in FIG. 2 or FIG. 5, and the sensitivity increases with respect to the speaker. It becomes possible. Further, the influence of ambient noise can be reduced as described above.
[0028]
【The invention's effect】
As described above in detail, in the present invention, an optical microphone using a VCSEL is used as a microphone used in a mobile phone device, and the directivity of the optical microphone is changed or switched based on the usage state of the mobile phone. As a result, good wave receiving characteristics can be obtained regardless of the usage state of the mobile phone device.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing a peripheral circuit of an optical microphone used in the present invention.
FIG. 2 is a diagram showing a change in a directivity pattern of an optical microphone element used in the present invention.
FIG. 3 is a diagram showing a structure of an optical microphone element used in the present invention.
FIG. 4 is a circuit diagram showing a schematic configuration of an optical microphone device used in the present invention.
FIG. 5 is a diagram showing a change in the directivity pattern of the optical microphone element shown in FIG. 3;
FIG. 6 is a directional pattern diagram of an optical microphone element used in the present invention.
FIG. 7 is an external view showing a schematic configuration of a conventional mobile phone device.
FIG. 8 is an external view showing a schematic configuration of a mobile phone device according to the present invention.
FIG. 9 is a diagram showing a use state of the mobile phone device according to the present invention.
FIG. 10 is a circuit diagram showing a peripheral circuit of an optical microphone used in another embodiment of the present invention.
FIG. 11 is a diagram showing a basic structure of an optical microphone element used in the present invention.
FIG. 12 is a diagram showing a light emission intensity distribution of a VCSEL used in the present invention.
FIG. 13 is a diagram illustrating a two-dimensionally calculated emission intensity distribution of a VCSEL used in the present invention.
[Explanation of symbols]
2 diaphragm LD light emitting element PD light receiving element 7 sound wave 13 light source driving circuit 50 optical microphone element 55 proximity sensor 56 switch 100 negative feedback circuit 200 mobile phone device

Claims (2)

In a mobile phone device having a first use state in which it is used in close contact with the face and a second use state in which it is used while being separated from the face,
A sensor for detecting a separation distance from the face is attached to the device,
As a built-in microphone,
A substrate on which a vertical cavity surface emitting laser light emitting device in which the light emission intensity distribution is substantially uniform in a concentric manner is arranged, and an optical device for receiving radiation light of the light emitting device is arranged,
A diaphragm that is installed substantially in parallel and close to the position facing the substrate, vibrates by sound pressure, reflects light from the light emitting element and emits the light to the light receiving element,
A light source driving circuit that supplies a driving current to the light emitting element;
Using an optical microphone including a negative feedback circuit that supplies a part of the signal output from the light receiving element to the light source driving circuit as a negative feedback signal,
A portable telephone device, wherein the directivity of the optical microphone is controlled by changing the magnitude of the negative feedback signal according to the sensor signal indicating the separation distance. In a mobile phone device having a first use state in which it is used in close contact with the face and a second use state in which it is used while being separated from the face,
A proximity sensor that outputs a detection signal that is turned off when in the first use state and turned on when in the second use state is attached to the device,
As a microphone,
A substrate on which a vertical cavity surface emitting laser light emitting device in which the emission intensity distribution is substantially uniform concentrically is arranged, and a light receiving element for receiving emitted light of the light emitting device is arranged,
A diaphragm that is installed substantially in parallel and close to the position facing the substrate, vibrates by sound pressure, reflects light from the light emitting element and emits the light to the light receiving element,
A light source driving circuit that supplies a driving current to the light emitting element;
Using an optical microphone including a negative feedback circuit that supplies a part of the signal output from the light receiving element to the light source driving circuit as a negative feedback signal,
A portable telephone device, wherein the directivity of the optical microphone is controlled by switching the magnitude of the negative feedback signal in two stages in response to the detection signal.

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