Speaker for generating sound based on digital signal
To respond to an n-bit digital signal, a speaker ( 1 ) is provided that includes an sound pressure generator ( 10 ) including 2 i−1 piezoelectric elements ( 51, 52 , and 53 ) for an i-th bit, and a total of 2 n −1 stacked piezoelectric elements ( 51, 52 , and 53 ). Due to divided vibration of the piezoelectric elements ( 51, 52 , and 53 ), the speaker ( 1 ) has low directionality. Planar electrodes ( 80, 81, 82 , and 83 ), to which voltage is applied, are provided between the piezoelectric elements ( 51, 52 , and 53 ). By this means, all the piezoelectric elements can be driven using similar voltages, and high sound quality can be obtained without a problem of unit-to-unit differences between voltage sources.
1. A speaker comprising:
a signal division circuit for dividing an inputted digital signal into bit units;
n D/A converters for output of a voltage in the bit units based on n post-division digital signals divided by the signal division circuit, n being greater than or equal to 2; and
a sound pressure generator, including 2 n −1 stacked piezoelectric elements, for receiving the voltage output from the D/A converters, wherein
maximum output voltages of the n D/A converters are the same, and
the sound pressure generator includes 2 i-1 of the piezoelectric elements for receiving the voltage output from the D/A converters processing the post-division digital signal for an i-th order bit from a lower order bit of the digital signal, i being an integer ranging from 1 to n, and includes n through-hole electrodes corresponding to the n D/A converters.
2. A speaker comprising:
a signal division circuit for dividing an inputted digital signal into bit units;
n D/A converters for output of a voltage in the bit units based on n post-division digital signals divided by the signal division circuit, n being greater than or equal to 2; and
a sound pressure generator, including 2 n −1 stacked piezoelectric elements, for receiving the voltage output from the D/A converters, wherein
maximum output voltages of the n D/A converters are the same, and
the sound pressure generator includes 2 i-1 of the piezoelectric elements for receiving the voltage output from the D/A converters processing the post-division digital signal for an i-th order bit from a lower order bit of the digital signal, i being an integer ranging from 1 to n, and includes n through-hole electrodes corresponding to the n D/A converters, and an i-th through-hole electrode applies to 2 i-1 of the piezoelectric elements the voltage output from a D/A converter of the D/A converters processing the post-division digital signal for the i-th order bit from the lower order bit of the digital signal.
3. The speaker according to claim 2 , wherein
the sound pressure generator includes planar electrodes disposed between the 2 i-1 piezoelectric elements of the sound pressure generator, and
planar electrodes to which the voltage is applied from the through-hole electrode and planar electrodes to which the voltage is not applied from the through-hole electrode are alternatingly disposed.
4. The speaker according to claim 2 , wherein 2 or more of the sound pressure generators are bonded together via a flexible resin.
5. The speaker according to claim 4 , wherein the flexible resin is bent to form a cylindrical shape.
6. The speaker according to claim 3 , wherein 2 or more of the sound pressure generators are bonded together via a flexible resin.
7. The speaker according to claim 6 , wherein the flexible resin is bent to form a cylindrical shape.