Charging circuit and module using the same
A module includes a charging circuit and a driven unit. The charging circuit includes a power generation element and an electric storage element. The power generation element is connected to the electric storage element to charge the electric storage element. The electric storage element is connected to the driven unit to drive the driven unit with electric power stored. The power-generating voltage of the power generation element has a value equal to or more than the charging voltage of the electric storage element. The electric storage element is a secondary battery including a lithium-transition metal oxide in a positive electrode active material layer, and a lithium-titanium oxide of spinel-type crystal structure in a negative electrode active material layer.
1. A charging circuit comprising:
an electric storage element having a rated charging voltage:
a power generation element having a rated power generation voltage which is greater than the rated charging voltage, the power generation element being coupled to the electric storage unit so as to charge the electric storage element; and
the electric storage element having a positive electrode active material layer containing a lithium-transition metal oxide and a negative electrode active material layer containing lithium-titanium oxide having a spinel-type crystal structure.
2. The charging circuit according to claim 1 , wherein the rated power-generating voltage of the power generation element falls within the range of 100 to 130% of the rated charging voltage of the electric storage element.
3. The charging circuit according to one claim 1 , wherein the power generation element includes a dye-sensitized photoelectric conversion element, an amorphous Si photoelectric conversion element, a compound-semiconductor thin-film photoelectric conversion element, and/or an organic thin-film photoelectric conversion element.
4. The charging circuit according to claim 1 , wherein the power generation element is a photoelectric conversion element which when subjected to an illuminance in the range of 50 to 2000 lux generates a power-generating voltage which is at least 60% of the power-generating voltage of the photoelectric conversion element at 2000 lux.
5. The charging circuit according to claim 1 , wherein a protection circuit is located between the power generation element and the electric storage element.
6. The charging circuit according to claim 1 , wherein the positive electrode active material layer and the negative electrode active material layer are no more than 100 μm in thickness.
7. A module comprising the charging circuit according to claim 1 , and a circuit driven by the electric storage element of the charging circuit, the circuit having a rated operating voltage equal to or less than the rated charging voltage of the electric storage element.
8. The module according to claim 7 , wherein the circuit comprises a sensor that measures at least one of infrared, magnetism, temperature, humidity, atmospheric pressure, flow rate, illuminance, light, sound waves, odors, and tactile.
9. The module according to claim 7 , wherein the circuit comprises a radio communication unit, a storage unit, and a control unit that controls both the radio communication unit and the storage unit.
10. The module according to claim 9 , wherein the storage unit stores a personal identification number for identifying the module from other modules.
11. The module according to claim 7 , wherein the circuit comprises a display unit, and a control unit that controls the display unit.