MOBILE TELEPHONE DEVICE
It is intended to provide a cellular telephone apparatus which employs a single sound-producing body as both of a receiver for reproducing a speech sound and a speaker for reproducing a ringer tone and which can secure a necessary reproduction frequency characteristic for each of the reproduction of a speech sound and the reproduction of a ringer tone. During reproduction of a ringer tone, the characteristic of a lowpass filter 130 b is chosen as the frequency characteristic of a digital lowpass filter 130 , a speaker 135 is driven by rendering a preamplifier 133 b and a push-pull circuit 133 d of a speaker amplifier 133 in an active state and setting the output form (circuit configuration) of the speaker amplifier 133 to BTL output, and the signal pass-band is set to a pass-band of 100 Hz to 20 kHz. During reproduction of a speech sound, the characteristic of a lowpass filter 130 a is chosen as the frequency characteristic of the digital lowpass filter 130 , the speaker 135 is driven by rendering the preamplifier 133 b and the push-pull circuit 133 d of the speaker amplifier 133 in a halt state and setting the output form (circuit configuration) of the speaker amplifier 133 to single output, and the signal pass-band is set to a pass-band of 300 Hz to 3 kHz.
1 . A cellular telephone apparatus in which a single sound-producing body is used as both of a sound-producing body for reproducing a speech sound and a sound-producing body for reproducing a ringer tone and a drive circuit for driving the sound-producing body is a single drive circuit, comprising:
a drive circuit switching unit which switches a drive form of the drive circuit; and
a control unit which controls the switching of the drive form of the drive circuit.
2 . The cellular telephone apparatus according to claim 1 , wherein the drive form which is switched by the drive circuit switching unit includes BTL drive output and single drive output.
3 . The cellular telephone apparatus according to claim 1 , wherein the control unit causes switching of the drive form of the drive circuit so that BTL drive output is selected as the drive form of the drive circuit during reproduction of a ringer tone and single drive output is selected as the drive form of the drive circuit during reproduction of a speech sound.
4 . A cellular telephone apparatus in which a single sound-producing body is used as both of a sound-producing body for reproducing a speech sound and a sound-producing body for reproducing a ringer tone and a drive circuit for driving the sound-producing body is a single drive circuit, comprising:
a power circuit output state switching unit which switches an output state of a power circuit for the drive circuit for driving the sound-producing body between boosted voltage output and non-boosted voltage output, the sound-producing body using a piezoelectric device; and
a control unit which controls the switching of the output state of the power circuit for the drive circuit for driving the sound-producing body.
5 . The cellular telephone apparatus according to claim 4 , wherein the control unit performs a control so that the power circuit output state is made the boosted voltage output during reproduction of a ringer tone and the power circuit output state is made the non-boosted voltage output during reproduction of a speech sound.
6 . The cellular telephone apparatus according to claim 4 , further comprising a bias voltage switching unit which switches a bias voltage of an output-stage transistor of the drive circuit for driving the sound-producing body depending on which of a ringer tone and a speech sound is to be reproduced.
7 . The cellular telephone apparatus according to any one of claims 1 , wherein the control unit switches a signal pass-band characteristic of the drive circuit for driving the sound-producing body or a preprocessing circuit of the drive circuit depending on which of the ringer tone and the speech sound is to be reproduced.
8 . The cellular telephone apparatus according to claim 1 , wherein the control unit switches a signal pass-band characteristic of a post-processing circuit of the drive circuit for driving the sound-producing body depending on which of the ringer tone and the speech sound is to be reproduced.
9 . The cellular telephone apparatus according to claim 4 , wherein the control unit switches a signal pass-band characteristic of the drive circuit for driving the sound-producing body or a preprocessing circuit of the drive circuit depending on which of the ringer tone and the speech sound is to be reproduced.
10 . The cellular telephone apparatus according to claim 4 , wherein the control unit switches a signal pass-band characteristic of a post-processing circuit of the drive circuit for driving the sound-producing body depending on which of the ringer tone and the speech sound is to be reproduced.