Selection device
A selection device includes an acquisition part to acquire digital selection signals, and an output part to output selection signals to respective unit cells, each unit cell capable of being commanded to output the value zero. In the selection device, each selection signal is to command the unit cell to output a value corresponding to that selection signal; the sum of the values to be output as commanded by the respective selection signals, which are output to the respective unit cells, is a value determined in association with the digital selection signal; and if the output corresponding to the digital selection signal is the value zero, then selection signals each commanding to output a non-zero value (N) are output to some of the unit cells.
1. A selection device comprising:
an acquisition part which acquires a digital selection signal; and
an output part which outputs a selection signal to each of a plurality of unit cells which can be instructed to output a value 0, outputs of the plurality of unit cells being input to an adder, the adder outputting a value of a sum of the outputs of the plurality of unit cells, wherein
the selection signal instructs an output of a value corresponding to the selection signal to the unit cell,
the value output by the adder is a value determined according to the digital selection signal,
when the value output by the adder corresponding to the digital selection signal is a value 0, a unit cell exists which is output with a selection signal which instructs an output of a value N which is not 0,
a time average of the value output by the adder is a value 0 when the digital selection signal is a value 0, and
wherein the digital selection signal is a digital audio signal, each of the unit cells is a drive circuit which drives a voice coil, and the selection signal represents an existence and a polarity of a current which flows in the voice coil which is driven by the unit cell.
2. The selection device according to claim 1 , wherein when the value output by the adder which corresponds to the digital selection signal is a value 0, the number of unit cells output with selection signals which instruct outputs of value N which is not a value 0 becomes the same as the number of unit cells which are output with selection signals which instruct outputs of value −N.
3. The selection device according to claim 1 , wherein the output part includes a conversion part which outputs the number of unit cells which are instructed to perform outputs of values other than 0 according to the digital selection signal, and a selection part which outputs selection signals according to the number of unit cells which are output by the conversion part, wherein when the output corresponding to the digital selection signal is a value 0, the number of unit cells output by the conversion part is 2 or more.
4. The selection device according to claim 3 , wherein the conversion part selects from the number of two or more types of unit cells according to a digital selection signal corresponding to a value 0.
5. The selection device according to claim 3 , wherein the selection part measures the frequency of selection of the unit cell by the selection signal and determines, in order of smallest frequency of selection, a unit cell which is outputs with a selection signal which instructs an output of a value N which is not 0.
6. The selection device according to claim 1 , wherein the selection part instructs an output of a value of either 1, 0, or −1 to the unit cells.
7. The selection device according to claim 1 , wherein the output part includes a first selection circuit which outputs a selection signal of a unit cell which outputs a plus value and a second selection circuit which outputs a selection signal of a unit cell which outputs a minus value.
8. The selection device according to claim 7 , further comprising:
a first integration part which accumulates a selection signal output by the first selection circuit, and
a second integration part which accumulates a selection signal output by the second selection circuit,
wherein
the first selection circuit selects unit cells in order from the smallest selection frequency which indicates the results of accumulation by the first integration part, and the second selection circuit selects unit cells in order from the smallest selection frequency which indicates the results of accumulation by the second integration part.
9. The selection device according to claim 8 , wherein the first integration part and the second integration part each accumulates the sum of weighting a selection signal which is output by the first selection circuit and a selection signal which is output by the second selection circuit.
10. The selection device according to claim 7 , further comprising:
a third integration part which accumulates the sum of a selection signal which is output by the first selection circuit and a selection signal which is output by the second selection circuit, the first selection circuit and the second selection circuit selecting unit cells in order from the smallest selection frequency which indicates the results of accumulation by the third integration part.
11. The selection device according to claim 10 , wherein the third integration circuit includes three or more integration circuits.