JP2003198714A - Mobile phone - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mobile phone capable of making a hands-free speech while keeping the best speech quality under a condition where the housing is open or closed. <P>SOLUTION: Two kinds of delays for an inverted phase component for the open housing and the closed housing are prepared, to add the inverted phase component at a receiver side signal to a transmitter side for canceling echo. Two kinds of levels for a negative gain for the open housing and the closed housing are prepared to add the negative gain to a component left not cancelled for completely canceling the echo. An opening/closing detection switch 28 detects an opening state or a closing state of the housing to select a corresponding delay and a corresponding level of the negative gain to the detected state. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a mobile telephone.

[0002]

2. Description of the Related Art The mainstream casing structure of a mobile phone is shown in FIG.
As shown in, the conventional straight type (non-deformable type) has been changed to a folding type (variable type). this is,
Although there is a fashion trend in terms of design, from a technical point of view, since the mobile phone can be folded compactly, each functional module (large color display, simple It can be said that it is a rational structure because it is easy to mount a digital camera, etc.

However, the demand for smaller and lighter mobile telephones is still severe, and the demand for higher functionality of mobile telephones continues to be met, and various additional functions that were not required before are mounted one after another. As a result, each functional module in the housing, especially one with a large volume (board portion such as a radio circuit / control circuit that fulfills the basic functions of a mobile phone, a display, a battery, a speaker, etc.) The placement of is very limited.

Here, the focus is on the transmitting microphone and the loudspeaker which are acoustic parts (used for making a ringing tone for the incoming call and for reproducing the received voice from the other party during the call). Incoming ringing tones, which used to function with electronic buzzers, became the mainstream to play chord melodies with rich musicality as mobile phones became more sophisticated, so instead of electronic buzzers, large loudspeaker speakers It became common sense to install. By using this loudspeaker in this flow, it is possible to make a so-called hands-free call on a mobile phone, which is a call by loud sound reproduction of the received sound that could not be realized until now using a general fixed telephone or a dedicated external connection speaker. It became possible to do it. An important technical point in making this hands-free call is the echo that occurs when the received sound reproduced from the loudspeaker wraps around to the transmitting side (the voice from the other party returns to the other party and is heard. In the worst case, the occurrence of howling is prevented), that is, echo canceling.

As described above, the arrangement of the functional modules mounted on the mobile telephone is usually provided with a large number of restrictions, and in particular, the loudspeaker speaker has a sufficient reproduction volume and a wide reproduction band. Since it has a large volume when desired, its location is limited. An example of the arrangement of parts of the folding mobile phone will be described. As shown in FIG. 4, the battery unit 13 having the largest volume and the largest weight is provided.
In consideration of the lowering of the center of gravity for ensuring a sense of stability when the mobile phone 10 is held in the hand, the mobile phone 10 is the lower part of the mobile phone 10, that is, the lower side in normal use.
It is arranged on the back side of the lower case 11. Further, an operation key group 14 is arranged on the front side of the lower case 11. Then, since there is no more space left below the mobile phone 10, the loudspeaker 15 is at the upper part of the mobile phone 10, that is, the upper case 12 of the mobile phone 10 which is the upper side during normal use. In many cases, it is arranged on the back side (the display display 16 is arranged on the front side). Here, the positional relationship between the transmitting microphone and the loudspeaker 15 will be examined. The transmission microphone 17 is used in a normal communication mode (not the hands-free communication but the mobile phone 1
The most common state of the telephone as a telephone which is used by holding 0 in the hand and using it on the side of the head) is as close as possible to the mouth to secure sufficient sensitivity and S / N ratio. In many cases, it is arranged at the lowermost end of the lower part, that is, at the end of the lower case 11 opposite to the upper case 12. On the other hand, the loudspeaker 15 is often arranged on the upper rear surface of the mobile phone 10 (the rear surface of the upper case 12) as described above. As a result, as shown in FIG. 5, the positional relationship between the transmitting microphone 17 and the loudspeaker 15 is different when the mobile phone 10 (housing) is open and when it is closed. It will change significantly when it is far away or close when closed. Looking at this acoustically, ERL (echo return level: the amount by which the received sound wraps around to the transmitting side when the received voice uttered from the loudspeaker 15 wraps around the transmitting microphone 17, not the absolute value, but the receiving path. (Represented by the ratio of the signal electric level to the signal electric level sneaking into the transmitting side) and the delay time (time until the receiving sound sneak into the transmitting side) vary. As a numerical value in the present embodiment, the ERL value is about -25 to -30 dB when the foldable mobile phone of a general size having the above-described transmitting microphone and the speaker for loudspeaker is opened and closed. +5 when you are
+10 dB, delay time sonic speed 340 m / Sec
Then, it is about 500 μSec when opened and about 50 μSec when closed.

[0006]

In recent years, echo canceling during a call has been performed by a digital signal processor (DS).
It is generally performed by signal processing according to P). The principle thereof will be briefly described with reference to FIG. 2. An echo picked up by the transmitting microphone 17 is obtained by converting the signal on the receiving side into an antiphase by the adaptive filter 51 and adding it to the transmitting side by the adding section 52. Has been erased. This process has a feedback loop 53, detects an ERL value that changes every moment by a sequential adaptive calculation, and adjusts the addition amount of the antiphase component so that optimum echo canceling is always performed. To work. Furthermore, a DSP having a high-level echo canceling function has a "remaining echo suppressing means" composed of a remaining echo detecting section 54, a remaining echo suppressing section 55 and a subtracting section 56, detects an unerased echo, and leaves an unerased component. By adding a negative gain to, the echo is completely erased. At this time, since the level of the transmission signal generated by the speaker along with the unerased component of the echo is also reduced by the minus gain, if the minus gain of the residual echo suppressing means is too strong, the speech quality is deteriorated. Therefore, the peak value of the negative gain can be set arbitrarily by the telephone designer after verifying the optimum point. In a DSP without residual echo suppression means, if there is an unerased component of the echo, the echo path is completely blocked (muted) so that the echo is not transmitted to the other party. (While the other party speaks, this voice does not reach the other party) and the call quality deteriorates, so the phone designer also adjusts the activation threshold of the mute operation (how much the remaining unerased echo is allowed). It is generally possible.

The above-mentioned echo canceling is an echo canceling function by DSP processing having a high performance, but there is a limit to the allowable ERL value, and if there is a very large wraparound of the received voice, the echo cannot be erased. . As described above, in the case of the foldable mobile phone, it can be considered that the ERL value is low and the amount of echo remaining is small because there is a certain distance between the loudspeaker and the transmission microphone in the open state. . Therefore, it is often not necessary to perform the process of muting the transmission path. On the other hand, in the closed state, the ERL value becomes high because the distance between the transmitting microphone and the loudspeaker is shortened, and echoes often remain, and it is necessary to mute the transmitting path or to perform processing close to it. Come on. On the other hand, when looking at this canceling process on the time axis, the delay time is an important factor for the echo canceling process, and if the delay time becomes long, the delay time is estimated in advance and the anti-phase component in the echo canceller unit is estimated. It is necessary to slightly shift the addition timing of (1) by the delay operation of the adaptive filter 51 portion of FIG. This delay time estimation requires the condition that the distance relationship between the loudspeaker and the transmission microphone is always constant. In the case of the folding mobile phone as described above, the open state and the closed state are determined. Then, the delay time fluctuates, becomes large in the open state and becomes small in the closed state, and thus does not match.

In summary, when it is attempted to realize a hands-free call in a foldable mobile phone in which a transmitting microphone is arranged at the bottom of the mobile phone and a loudspeaker is arranged at the top of the mobile phone, the mobile phone is 2 of "ERL value" and "delay time" depending on whether it is open or closed
Two conditions will change. And when these two conditions are open, "ERL value is small, delay time is large"
Thus, the closed state is a condition that conflicts with "large ERL value, small delay time". Therefore, in the mobile phone having the above structure, if the open state is estimated and the echo cancellation adjustment is performed, the echo cancellation processing is not sufficiently performed in the closed state, and conversely, the echo cancellation adjustment is performed assuming the closed state. If you do, the echo cancellation processing will not be sufficient when opened. as a result,
When realizing a hands-free call in a mobile phone having the above structure, sufficient call quality cannot be obtained unless it is designed to operate only in either an open state or a closed state.

The present invention has been made in view of the above points,
An object of the present invention is to provide a mobile phone capable of performing a hands-free call while maintaining the best call quality under each condition regardless of whether the case is open or closed.

[0010]

A first mobile telephone of the present invention is a folding or sliding mobile telephone capable of opening and closing a housing, and converts a signal of a receiving side into an opposite phase to a transmitting side. A first echo canceling means for canceling the echo by adding to the first echo canceling means, and a first echo canceling means for detecting the echo remaining unerased and adding a negative gain to the unerased residual component to cancel the echo. Two types of echo canceling means and two kinds of delay amounts of the anti-phase component when adding the anti-phase component to the transmitting side by the first echo canceling means are provided for the case opened and the case closed. And a unit for storing the negative gain level of the second echo canceling unit in the memory by preparing two types, one for opening the casing and one for closing the casing. Inspection to detect opening and closing Means and, when the detecting means detects the open state of the housing, the delay amount and the minus gain level for opening the housing are read out from the memory to the first and second echo canceling means. When the closed state of the casing is detected by the setting means, the delay amount and the minus gain level for closing the casing are read out from the memory to the first and second echo canceling means. And a control means for setting.

In a preferred form, the delay amount is set for opening the housing> closing the housing, and the level of the negative gain is set for opening the housing <closing the housing. It Also, the control means sets the delay amount and the minus gain level in the first and second echo canceling means during the hands-free call as described above.

The second mobile telephone of the present invention is a folding or sliding mobile telephone capable of opening and closing the housing, and an echo is generated by converting the signal on the receiving side to the opposite phase and adding it to the transmitting side. Echo canceling means for erasing
The echo canceling means detects the echo left unerased, and if the unerased component exceeds a predetermined threshold value, muting means for muting the transmission path, and the echo cancellation means transmits the antiphase component. Means for storing two kinds of delay amounts of the anti-phase component when adding to the side, one for opening the case and one for closing the case, and storing in a memory, and a threshold value of the mute means when the case is opened. For storing two types of data, one for storage and one for closing the housing, and storing it in the memory, a detecting means for detecting opening / closing of the housing, and a memory for detecting the open state of the housing by the detecting means. If the delay amount and the threshold value for opening the housing are read from and are set in the echo canceling means and the mute means, and the closed state of the housing is detected by the detecting means, the housing is read from the memory. Amount of delay and threshold for closing Characterized by comprising a control means for reading Te is set to the echo canceling means and mute means.

In a preferred mode of this second mobile telephone, the delay amount is set so that when the housing is opened> when the housing is closed, and the threshold value is when the housing is opened> the above It is set for when the case is closed. Further, the control means sets the delay amount and the threshold value in the echo canceling means and the mute means as described above during a hands-free call.

Further, in the above-mentioned mobile phone of the present invention, as a preferred form, the case is constructed such that the lower end of the upper case is rotatably or slidably connected to the upper end of the lower case. A loudspeaker for loudspeaker is arranged in the lower case, and a transmitting microphone is arranged in the lower case.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a mobile telephone according to the present invention will be described in detail with reference to the accompanying drawings. The mobile phone according to the embodiment of the present invention is a foldable mobile phone. As shown in FIG. 4, the foldable mobile telephone has a lower case 11 having an upper end rotatably connected to a lower end of an upper case 12, and the case (housing) opened as shown on the left side of FIG. The state can be changed to the closed state (folded state) shown on the right side of FIG. An operation key group 14 and a transmission microphone 17 are arranged on the front side of the lower case 11, and a battery section 13 is provided on the rear side of the lower case 11. On the other hand, the liquid crystal display 16 and the receiving speaker 18 are arranged on the front surface of the upper case 12, and the loud speaker 15 is arranged on the rear surface of the upper case 12. Therefore, by using the loudspeaker 15 and the transmitting microphone 17, a hands-free call is made in a state where the casing shown on the left side of FIG. 5 is open and a state where the casing shown on the right side of FIG. 5 is closed. It can be performed. The hands-free call is activated by operating the operation key 14. A normal conversation is conducted by the transmitting microphone 17 and the receiving speaker 18. The reception speaker 18 and the loudspeaker 15 can be switched by a switch (not shown),
Switch for loudspeaker 1 for hands-free calling
It has been switched to the 5 side.

FIG. 1 shows a circuit block diagram of the mobile telephone according to the embodiment of the present invention as described above. This block diagram shows an R that is connected to the antenna 21 and performs a transmission / reception operation.
An F circuit 22, a digital signal processor (DSP) 30 for digitally processing a transmission / reception signal, and the DSP
A D / A converter 23 for D / A converting the reception signal output from 30 and a loudspeaker 15 for expanding the reproduction of the reception signal D / A converted by the D / A converter 23.
And a transmitting microphone 17 for inputting the voice of the speaker, an A / D converter 24 for A / D converting the transmitting signal input from the transmitting microphone 17 and outputting it to the DSP 30, and a CPU for controlling the whole. The part 25, the memory 26 and the ROM 27 connected to the CPU part 25 for storing programs and various data, and the case (the upper case 12 and the lower case 11 in FIG. 4) connected to the CPU part 25 to open and close. An open / close detection switch 28 for detecting. The open / close detection switch 28 operates mechanically, electrically, magnetically,
Various types such as optical type are conceivable.

The DSP 30 comprises a baseband modem section 40 for modulating / demodulating a transmission / reception signal and an echo canceller section 50 for carrying out an echo canceling process. The echo canceller unit 50 comprises a first echo canceling means 60 and a second echo canceling means 70, as shown in FIG. The first echo canceling means 60 is composed of an adaptive filter 51, an adder 52 and a feedback loop 53, and converts the signal on the receiving side into an opposite phase and adds it to the transmitting side to pick up the echo picked up by the transmitting microphone 17. Erase. The second echo canceling means 70 includes a residual echo detector 54 and a residual echo suppressor 55.
The first echo canceling means 60 detects the echo left unerased and adds a negative gain to the unerased component to completely cancel the echo.

In the mobile telephone according to the embodiment of the present invention as described above, the opening / closing detection switch 28 can detect the opening / closing of the housing (the upper case 12 and the lower case 11 in FIG. 4).
When the open / close detection switch 28 detects the open state of the housing (left side in FIG. 5) during a hands-free call using the transmitting microphone 17 and the loudspeaker 15, the first echo canceling means 60 When adding anti-phase components,
The delay amount of the antiphase component is set to be large. On the other hand, when the open / close detection switch 28 detects the closed state of the housing (right side in FIG. 5), the delay amount is set to be small. That is, in the mobile telephone according to the embodiment of the present invention, the delay time (the time until the received sound wraps around to the transmitting side) is large in the open state of the housing, and accordingly, the delay of the antiphase component to be added is delayed. Set the amount large (to about 500 μSec).
On the other hand, since the delay time is small when the case is closed,
Correspondingly, the delay amount of the antiphase component to be added is set small (to about 50 μSec). That is, the delay amount of the antiphase component to be added is optimized in each of the case open state and the case closed state. Here, as an example, the value is set based on the numerical value of one embodiment described in the related art.

Further, the ERL value is small in the open state of the housing (-25 to -30 dB), and even if there is an unerased echo left by the first echo canceling means 60, it is a small value. In the state where the open state of the housing is detected by the open / close detection switch 28, the negative gain level (fixed value) of the second echo canceling means (residual echo suppressing means) 70 is set small (suppressed small). . As a result, the residual echo can be surely erased, the transmission signal can be prevented from being excessively attenuated, and good communication quality can be maintained. On the other hand, the ERL value is large (+5 to +10
dB) Case closed state (open / close detection switch 2 indicates the closed state of the case)
8), a large unerased component may be generated as an unerased part of the echo of the first echo canceling means 60, and it is possible to suppress this large unerased part as well. The negative gain level (fixed value) of the second echo canceling means 70 is set large (suppressed greatly). As a result, the level of the transmitted signal is slightly lowered, but even a large residual echo can be erased and good speech quality can be secured.

The above setting method will be described more specifically with reference to FIGS. 1 and 2. A pair of a parameter representing the delay amount and a parameter representing the level of the minus gain (both parameters are parameters of about 2 to 4 bytes) are set as “for housing opening” and “for housing closing”. 2 types are prepared and stored in the ROM 27 in advance. When a hands-free call is started, the open / close detection switch 28 detects the open / closed state of the housing, and if the open / closed detection switch 28 detects the open state of the housing, the information from the open / close detection switch 28 is used as a basis. In addition, the CPU section 25 reads the parameters (delay amount and minus gain level) for “when the housing is opened” from the ROM 27, and the delay amount and minus gain level are sent to the first and second echo canceling means 60 and 70. Set. On the other hand, if the open / closed detection switch 28 detects the closed state of the housing, the CPU 25 uses the information from the open / closed detection switch 28 to set parameters for "closed housing" (delay amount and negative gain level). ) Is read from the ROM 27, and the delay amount and the minus gain level thereof are set in the first and second echo canceling means 60 and 70. Also, open the housing during a call ←
→ When the open / close detection switch 28 detects that the housing is opened or the housing is closed due to the closing operation, the setting operation is similar to the above.

As described above, according to the above mobile telephone, the delay amount of the first echo canceling means 60 and the level of the negative gain of the second echo canceling means 70 are set to the open state and the closed state of the case. It can be optimized for each of the states. Therefore, it is possible to perform a hands-free call while maintaining a sufficient call quality regardless of whether the case is open or closed. Further, the setting values (delay amount and minus gain level) are automatically selected by the CPU unit 25 for convenience.

In the above embodiment, the residual echo suppressing means (second echo canceling means 70) suppresses and erases the echo left unerased by the first echo canceling means 60, but instead of this residual echo suppressing means. It is also possible to provide mute means for muting the transmission path when the level of the remaining echoes exceeds a predetermined threshold value.
In this case, in the mobile phone of the present invention, two types of threshold values for the mute means, "for housing opening" and "for housing closing", are prepared, and can be selected depending on whether the housing is open or closed. Switch threshold settings. The threshold value is set to "for case opening">"for case closing". This facilitates muting when the housing is closed with a large ERL value and a very large echo amount, and the call quality can be maintained by muting. On the other hand, E
When the housing with a low RL value and a small amount of echo is opened, it is difficult to mute, and it is possible to continue the transmission and ensure the communication quality. The threshold value is stored in the ROM 27 of FIG. 1, and the CPU 25 reads out either “for housing opening” or “for housing closing” according to the detection state of the open / close detection switch 28. Set to mute means.

Although the case where the lower end of the upper case 12 rotates to cover the lower case 11 has been described in the present embodiment, the upper case 12 is configured to be slidable.
Even when the upper case 12 slides to cover the lower case 11, the opening and closing of the housing is detected and controlled in the same manner as in the above embodiment.

[0024]

As described in detail above, according to the mobile telephone of the present invention, the best call quality can be maintained under each condition regardless of whether the case is open or closed, and the hands-free call can be made. It can be carried out.

[Brief description of drawings]

FIG. 1 is a circuit block diagram showing an embodiment of a mobile phone of the present invention.

FIG. 2 is a specific circuit diagram of an echo canceller unit.

FIG. 3 is a perspective view showing the transition of the housing structure of the mobile phone.

FIG. 4 is a perspective view showing a foldable mobile phone in an open state.

FIG. 5 is a perspective view showing a foldable mobile phone in an open state and a closed state.

[Explanation of symbols]

25 CPU section 27 ROM 28 Open / close detection switch 50 Echo canceller section 60 First Echo Canceling Means 70 Second Echo Canceling Means

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Claims (7)

[Claims] 1. A folding-type or sliding-type mobile telephone capable of opening and closing a casing, wherein first echo canceling means for canceling an echo by converting a signal on the receiving side into an opposite phase and adding the signal to the transmitting side. A second echo canceling means for detecting an echo left unerased by the first echo canceling means, and canceling the echo by adding a negative gain to the unerased residual component; and the first echo canceling means. Means for preparing and storing in the memory two types of delay amounts of the anti-phase component when adding the anti-phase component to the transmitting side, one for the case opened and one for the case closed, and the second echo canceller. Means for preparing two types of negative gain levels of the means, one for opening the housing and one for closing the housing, and storing the same in a memory; a detecting means for detecting opening / closing of the housing; Open state When detected, the delay amount for opening the housing and the level of the minus gain are read from the memory and set in the first and second echo canceling means, and the detecting means determines the closed state of the housing. When it is detected, the control means for reading the delay amount for closing the housing and the level of the minus gain from the memory and setting them in the first and second echo canceling means is provided. Body phone. 2. The delay amount is set for opening the housing> closing the housing, and the level of the negative gain is set for opening the housing <closing the housing. The mobile phone according to claim 1, wherein: 3. The control means sets the delay amount and the minus gain level in the first and second echo canceling means as described above during a hands-free call. The mobile phone according to 2. 4. A folding or sliding mobile telephone capable of opening and closing a housing, and echo canceling means for canceling an echo by converting a signal on the receiving side to an opposite phase and adding the signal to the transmitting side. The echo canceling means detects the remaining unerased echo, and if the remaining unerased component exceeds a predetermined threshold value, muting means for muting the transmission path; and the echo cancellation means for transmitting the opposite phase component on the transmitting side. Means for storing two types of delay amounts of the anti-phase component when adding to the case, one for opening the case and one for closing the case, and storing it in the memory; and a threshold value of the mute means for opening the case. And a means for storing two kinds of data for closing the housing in the memory, a detecting means for detecting the opening / closing of the housing, and a detecting means for detecting the open state of the housing, from the memory. Delay amount for opening the case And a threshold value are read out and set in the echo canceling means and the mute means, and when the detecting means detects the closed state of the housing, the delay amount and the threshold value for closing the housing from the memory. And a control means for reading out and setting the echo canceling means and the mute means. 5. The delay amount is set for opening the housing> closing the housing, and the threshold value is set for opening the housing> closing the housing. The mobile phone according to claim 4, wherein the mobile phone is a mobile phone. 6. The control unit according to claim 4, wherein the delay amount and the threshold value are set in the echo canceling unit and the mute unit as described above during a hands-free call. Mobile phone. 7. The housing is configured such that a lower end of an upper case is rotatably or slidably connected to an upper end of a lower case, a loudspeaker for loudspeaker is arranged in the upper case, and a voice is transmitted to the lower case. 7. The mobile phone according to claim 1, further comprising a microphone.