Telecommunications – Transmitter and receiver at same station – Radiotelephone equipment detail
Reexamination Certificate
1998-06-22
2001-07-10
Urban, Edward F. (Department: 2683)
Telecommunications
Transmitter and receiver at same station
Radiotelephone equipment detail
C340S388400, C379S373040
Reexamination Certificate
active
06259935
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electro-mechanical-acoustic transducing device which is used for generating a ring-back calling tone or vibration in portable terminal devices such as a portable telephone, a pager, a personal handy phone set, and the like.
2. Description of the Related Art
As means for informing a user that a call is coming, a conventional portable terminal device (e.g., a conventional portable telephone, pager, personal handy phone set, or the like) generally includes both a small beeper for generating a bell sound and a micromotor in which vibration is caused by a weight eccentrically attached to a rotation shaft. On the other hand, U.S. Pat. No. 5,524,061 discloses a portable telephone containing an electro-mechanical-acoustic transducing device which realizes the generation of sound or vibration for informing a user that a call is coming using one unit in order to reduce the size and weight of a portable terminal device.
According to the electro-mechanical-acoustic transducing device disclosed in above-mentioned U.S. Pat. No. 5,524,061, by supplying an electric signal to an electromagnetic coil of an electromagnetic driver which is attached to a soundboard, a magnetic motional mass unit is vibrated due to a magnetic force affecting a region between the electromagnetic coil and the magnetic motional mass unit. The vibration is transferred to the soundboard, thereby generating vibration and sound. Such vibration becomes intensified in the vicinity of a resonance frequency of a mechanical resonance system constituted by the magnetic motional mass unit and a non-linear spring that supports the magnetic motional mass unit. Thus, the electric signal to be supplied to the electromagnetic coil is set to have a predetermined range of frequency containing the aforementioned resonance frequency (more accurately, so as to repeatedly sweep the predetermined frequency range in a successive manner) by a sweep frequency generator. The vibration reaches its maximum when the mechanical resonance frequency of the magnetic motional mass unit and the non-linear spring coincides with the frequency of the electric signal supplied to the electromagnetic coil.
According to such a conventional system, however, the supplied electric signal is swept in the entire frequency range including frequencies which do not correspond to the mechanical resonance frequency. The vibration becomes small when the electric frequency does not correspond to the mechanical resonance frequency upon sweeping. Therefore, in the above conventional system, an efficiency in the output of mechanical vibration with respect to an electrical input is often low.
SUMMARY OF THE INVENTION
An electro-mechanical-acoustic transducing device of the present invention includes: an electro-mechanical-acoustic transducer which has at least one resonance frequency, for converting an input electric signal into only vibration, or into both vibration and sound; a signal supplying unit for supplying a signal in a frequency band which includes at least one of the resonance frequencies of the electro-mechanical-acoustic transducer as the input signal of the electro-mechanical-acoustic transducer; and a frequency detector for detecting a signal component having a frequency corresponding to the mechanical resonance frequency of the electro-mechanical-acoustic transducer in an electric signal which is output from the electro-mechanical-acoustic transducer, and outputting the signal component as a part of an input signal to the signal supplying unit.
In one embodiment, the signal supplying unit is an amplifier for amplifying a given input signal.
In one embodiment, the amplifier amplifies a noise which is generated in an electrical circuit system including at least one of the amplifier and the frequency detector as the input signal.
In another embodiment, a signal generator is further included in generating a signal in a frequency band including at least one of the resonance frequencies of the electro-mechanical-acoustic transducer and supplying the signal as the input signal of the amplifier.
In such a case, the amplifier may amplify a noise which is generated in an electrical circuit system including at least one of the amplifier and the frequency detector as a part of the input signal.
In one embodiment, the electro-mechanical-acoustic transducer is structured so as to have at least two mechanical resonance frequencies and to respectively convert input electric signals corresponding to at least two of the resonance frequencies into vibration or sound. The signal supplying unit includes a first oscillator for oscillating a first electric signal in a frequency band including at least one of the resonance frequencies of the electro-mechanical-acoustic transducer and outputting the first electric signal as the input signal of the electro-mechanical-acoustic transducer, and a second oscillator for oscillating a second electric signal at a frequency corresponding to the at least one resonance frequency of the electro-mechanical-acoustic transducer and outputting the second electric signal as the input signal of the electro-mechanical-acoustic transducer. And a controller is further provided for controlling the second oscillator so as to oscillate a signal having the frequency corresponding to the mechanical resonance frequency of the electro-mechanical-acoustic transducer at a predetermined timing based on detection information of the frequency detector.
Furthermore, a voltage comparator may be further included for comparing an output voltage of the frequency detector with a predetermined reference potential, and supplying information regarding a potential difference to the controller.
In one embodiment, the signal supplying unit includes an oscillator for oscillating an electric signal in a frequency band including at least one of the resonance frequencies of the electro-mechanical-acoustic transducer, and outputting the electric signal as the input signal of the electro-mechanical-acoustic transducer. A controller is further provided for controlling the oscillator so as to oscillate a signal having a frequency corresponding to the mechanical resonance frequency of the electro-mechanical-acoustic transducer at a predetermined timing based on detection information of the frequency detector.
Furthermore, a voltage comparator may be further included for comparing an output voltage of the frequency detector with a predetermined reference potential and supplying information regarding a potential difference to the controller.
The controller may control the oscillator so that the oscillator performs oscillation of the electric signal in the frequency band including at least one of the resonance frequencies of the electro-mechanical-acoustic transducer and oscillation of the signal having the frequency corresponding to the mechanical resonance frequency of the electro-mechanical-acoustic transducer which is detected by the frequency detector in a time-divisional manner.
Alternatively, the controller may control the oscillator so that the oscillator oscillates the electric signal so as to sweep the frequency band including at least one of the resonance frequencies of the electro-mechanical-acoustic transducer, and upon detection by the frequency detector of the mechanical resonance frequency of the electro-mechanical-acoustic transducer, oscillates the signal having the frequency corresponding to the detected mechanical resonance frequency.
The frequency detector may include a bridge circuit constituted by using an electrical impedance of a predetermined component of the electro-mechanical-acoustic transducer as one of component circuit elements.
The predetermined component of the electro-mechanical-acoustic transducer may be a voice coil.
Each of the other three component circuit elements in the bridge circuit may be a circuit element containing a resistance component.
In one embodiment, in the case where an electrical impedance of the predetermined component of the electro-mechanical-a
Kuze Mitsukazu
Saiki Shuji
Sato Kazue
Usuki Sawako
Matsushita Electrical Industrial Co. Ltd.
Renner, Otto, Boiselle & Sklar LLP
Urban Edward F.
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