1. A method for providing electronic content, comprising:
presenting a list of a plurality of selectable electronic-content-items available for downloading to a first mobile electronic device;
receiving a request for one or more selected electronic-content-items of the plurality of selectable electronic-content-items;
in response to receiving the request, a second mobile electronic device retrieving the one or more selected electronic-content-items; and
the second mobile electronic device transmitting the one or more selected electronic-content-items to the first mobile electronic device via a short-range wireless connection between the first and second mobile electronic devices.
2. The method of claim 1, wherein presenting the list comprises the second mobile electronic device transmitting the list of the plurality of selectable electronic-content-items via the short-range wireless connection to the first mobile electronic device.
3. The method of claim 2, wherein transmitting the list is performed by a short-range communications subsystem of the second mobile electronic device
4. The method of claim 1, wherein presenting the list comprises the second mobile electronic device displaying the list of selectable electronic-content-items on a display element of the second mobile electronic device.
5. The method of claim 4, wherein receiving the request further comprises receiving at an inputoutput subsystem of the second mobile electronic device a selection for the one or more selected electronic-content-items of the plurality of selectable electronic-content-items.
6. The method of claim 1, wherein presenting the list is in response to receiving a request for the list of the plurality of selectable electronic-content-items.
7. The method of claim 6, wherein presenting the list further comprises receiving the request from the first mobile electronic device at a short-range communications subsystem of the second mobile electronic device via the short-range wireless connection.
8. The method of claim 6, wherein presenting the list further comprises receiving the request at an inputoutput subsystem of the second mobile electronic device.
9. The method of claim 8, wherein the inputoutput subsystem of the second mobile electronic device comprises a user interface of the second mobile electronic device.
10. The method of claim 1, wherein the request for one or more selected electronic-content-items is received at a short-range communications subsystem of the second mobile electronic device.
11. The method of claim 1, wherein receiving the request for one or more selected electronic-content-items further comprises:
receiving at an inputoutput subsystem of the second mobile electronic device selection of the one or more selected electronic-content-items.
12. The method of claim 11, wherein the inputoutput subsystem of the second mobile electronic device comprises a user interface of the second mobile electronic device.
13. The method of claim 1, further comprising retrieving the plurality of selectable electronic-content-items and storing the retrieved plurality of selectable electronic-content-items in an electronic content repository of the second mobile electronic device.
14. The method of claim 1, wherein the plurality of selectable electronic-content-items is available in an electronic content repository of the second mobile electronic device and retrieving comprises an electronic content manager of the mobile electronic device retrieving the one or more selected electronic-content-items from the electronic content repository.
15. The method of claim 1, wherein the plurality of selectable electronic-content-items is available from a content server external the second mobile electronic device, the method further comprising:
the second mobile electronic device establishing a long-range wireless connection with the content server;
a long-range communication subsystem of the second mobile electronic device querying the content server;
the long range communication subsystem receiving via the long-range wireless connection the plurality of selectable electronic-content-items from the content server;
in response to the request for one or more selected electronic-content-items of the plurality of selectable electronic-content-items received by the second mobile electronic device, the second mobile electronic device retrieving the one or more selected electronic-content-items by requesting and receiving from the content server via the long-range wireless connection the one or more selected electronic-content-items; and
a short-range communications subsystem of the second mobile electronic device transmitting the retrieved one or more selected electronic-content-items via the short-range wireless connection to the first mobile electronic device.
16. The method of claim 15, wherein the plurality of selectable electronic-content-items reside in a content repository coupled to the content server and further comprising the content server retrieving the plurality of selectable electronic-content-items from the content repository.
17. The method of claim 15, further comprising:
after receiving the request, the second mobile electronic device re-establishing the long-range wireless connection to the content server;
18. The method of claim 1, wherein the plurality of selectable electronic-content-items is available from a content server.
19. The method of claim 18, wherein in response to the second mobile electronic device receiving the request for one or more selected electronic-content-items of the plurality of selectable electronic-content-items, the method further comprising:
a long-range communication subsystem of the second mobile electronic device retrieving the one or more selected electronic-content-items from the content server via a long-range wireless connection with the content server; and
a short-range communications subsystem of the second mobile electronic device transmitting the retrieved one or more selected electronic-content-items via the short-range wireless connection.
20. The method of claim 19, further comprising:
after receiving the request, the second mobile electronic device establishing the long-range wireless connection to the content server;
21. The method of claim 19, further comprising an electronic content manager of the second mobile electronic device storing the retrieved one or more selected electronic-content-items in an electronic content repository of the second mobile electronic device.
22. The method of claim 18, the method further comprising:
a long-range communication subsystem of the second mobile electronic device retrieving the plurality of selectable electronic-content-items from the content server via a long-range wireless connection with the content server; and
in response to the mobile electronic device receiving the request, a short-range communications subsystem of the second mobile electronic device transmitting the retrieved one or more selected electronic-content-items via the short-range wireless connection to the first mobile electronic device.
23. The method of claim 18, further comprising:
after receiving the request, the second mobile electronic device establishing the long-range wireless connection to the content server;
24. The method of claim 18, further comprising:
an electronic content manager of the second mobile electronic device storing the retrieved plurality of selectable electronic-content-items in an electronic content repository of the second mobile electronic device.
25. The method of claim 1, wherein transmitting the one or more selected electronic-content-items further comprises a short-range communications subsystem of the second mobile electronic device transmitting the one or more selected electronic-content-items via the short-range wireless connection to the first mobile electronic device.
26. The method of claim 1, further comprising establishing the short-range wireless connection between the first and second mobile electronic devices.
27. The method of claim 26, wherein establishing the short-range wireless connection between the first and second mobile electronic devices creates a personal area network (PAN) between the first and second mobile electronic devices.
28. The method of claim 1, wherein the plurality of selectable electronic-content-items comprise one or more of an electronic book, video, music, multimedia, and an e-mail attachment.
29. The method of claim 1, further comprising:
the second mobile electronic device transmitting an electronic contact list via the short-range wireless connection, wherein the electronic contact list is an updated list of electronic content stored on the second mobile electronic device.
30. The method of claim 1, the first mobile electronic device having a display of sufficient size to enable visual viewing of electronic content.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
What is claimed is:
1. A switching power supply unit comprising:
a transformer having a primary winding and a secondary winding;
a capacitor coupled to the transformer;
a first switching circuit connected in series with a series circuit of the primary winding and an input power source, the first switching circuit comprising a parallel circuit comprising a first switching element, a first diode and a first capacitor;
a second switching circuit connected in parallel with the primary winding, the second switching circuit comprising a parallel circuit comprising a second switching element, a second diode and a second capacitor;
first and second switching controlling circuits connected to the first and second switching circuits, respectively for controlling the first and second switching elements so as to turn onoff alternately with a period in which the first and second switching elements turn off being interposed therebetween;
a rectifying and smoothing circuit connected to the secondary winding; and
a voltage detection and voltage reduction circuit having a control signal input terminal and connected to the rectifying and smoothing circuit, the voltage detection and voltage reduction circuit detecting an output voltage of the rectifying and smoothing circuit and outputting a feedback signal to the first switching controlling circuit such that an output voltage of the rectifying and smoothing circuit is stabilized at one of a first voltage and a second voltage lower than the first voltage based on a signal applied to the control signal input terminal.
2. The switching power supply unit of claim 1, wherein at least one of the first and second switching elements comprises a field-effect transistor.
3. The switching power supply unit of claim 1, wherein the transformer includes a first driving winding for generating a voltage driving the first switching element into conduction and a second driving winding for generating a voltage driving the second switching element to perform a self-excited oscillation.
4. The switching power supply unit of claim 2, wherein the transformer includes a first driving winding for generating a voltage driving the first switching element into conduction and a second driving winding for generating a voltage driving the second switching element to perform a self-excited oscillation.
5. The switching power supply unit of claim 1, wherein the transformer includes one of a leakage inductor disposed between the primary winding and the secondary winding and an inductor connected in series with the primary winding; and
the inductor and the capacitor form a resonance circuit.
6. The switching power supply unit of claim 1, wherein the rectifying and smoothing circuit includes a diode, and at least one of a parasitic capacitance of the diode and a capacitive impedance connected in parallel to the diode; and
the at least one of the parasitic capacitance and the capacitive impedance and an inductance of the transformer form a resonance circuit during a period in which the first and second switching elements are both turned off.
7. The switching power supply unit of claim 2, wherein the rectifying and smoothing circuit includes a diode, and at least one of a parasitic capacitance of the diode and a capacitive impedance connected in parallel to the diode; and
the at least one of the parasitic capacitance and the capacitive impedance and an inductance of the transformer form a resonance circuit during a period in which the first and second switching elements are both turned off.
8. The switching power supply unit of claim 1, wherein the second switching controlling circuit includes a time constant control circuit comprised of a transistor, a capacitor, and an impedance circuit.
9. The switching power supply unit of claim 1, wherein an on-period of the first switching element is controlled so as to control the output voltage so that an on-period of the second switching element is maintained approximately constant.
10. The switching power supply unit of claim 2, wherein an on-period of the first switching element is controlled so as to control the output voltage so that an on-period of the second switching element is maintained approximately constant.
11. The switching power supply unit of claim 3, wherein an on-period of the first switching element is controlled so as to control the output voltage so that an on-period of the second switching element is maintained approximately constant.
12. The switching power supply unit of claim 5, wherein an on-period of the first switching element is controlled so as to control the output voltage so that an on-period of the second switching element is maintained approximately constant.
13. The switching power supply unit of claim 6, wherein an on-period of the first switching element is controlled so as to control the output voltage so that an on-period of the second switching element is maintained approximately constant.
14. The switching power supply unit of claim 8, wherein an on-period of the first switching element is controlled so as to control the output voltage so that an on-period of the second switching element is maintained approximately constant.
15. The switching power supply unit of claim 1, further comprising a control circuit for controlling the time of conduction of the second switching element such that at least one of the first and second switching elements is brought into a conductive state at a voltage of zero or after dropping down to a voltage of zero.
16. The switching power supply unit of claim 2, further comprising a control circuit for controlling the time of conduction of the second switching element such that at least one of the first and second switching elements is brought into a conductive state at a voltage of zero or after dropping down to a voltage of zero.
17. The switching power supply unit of claim 3, further comprising a control circuit for controlling the time of conduction of the second switching element such that at least one of the first and second switching elements is brought into a conductive state at a voltage of zero or after dropping down to a voltage of zero.
18. The switching power supply unit of claim 5, further comprising a control circuit for controlling the time of conduction of the second switching element such that at least one of the first and second switching elements is brought into a conductive state at a voltage of zero or after dropping down to a voltage of zero.
19. The switching power supply unit of claim 6, further comprising a control circuit for controlling the time of conduction of the second switching element such that at least one of the first and second switching elements is brought into a conductive state at a voltage of zero or after dropping down to a voltage of zero.
20. The switching power supply unit of claim 8, wherein the second switching controlling circuit controls the time of conduction of the second switching element such that at least one of the first and second switching elements is brought into a conductive state at a voltage of zero or after dropping down to a voltage of zero.
21. The switching power supply unit of claim 9, further comprising a control circuit for controlling the time of conduction of the second switching element such that at least one of the first and second switching elements is brought into a conductive state at a voltage of zero or after dropping down to a voltage of zero.
22. The switching power supply unit of claim 1, wherein the output voltage is decreased by the voltage detection and voltage reduction circuit to reduce current fed back to an input power supply; and
operations of the first and second switching elements are intermittent oscillation operations in which an oscillation period for performing onoff switching operations and a suspension period for performing no switching operations are alternately repeated.
23. The switching power supply unit of claim 2, wherein the output voltage is decreased by the voltage detection and voltage reduction circuit to reduce current fed back to on input power supply; and
operations of the first and second switching elements are intermittent oscillation operations in which an oscillation period for performing onoff switching operations and a suspension period for performing no switching operations are alternately repeated.
24. The switching power supply unit of claim 3, wherein the output voltage is decreased by the voltage detection and voltage reduction circuit to reduce current fed back to an input power supply; and
operations of the first and second switching elements are intermittent oscillation operations in which an oscillation period for performing onoff switching operations and a suspension period for performing no switching operations are alternately repeated.
25. The switching power supply unit of claim 5, wherein the output voltage is decreased by the voltage detection and voltage reduction circuit to reduce current fed back to an input supply; and
operations of the first and second switching elements are intermittent oscillation operations in which an oscillation period for performing onoff switching operations and a suspension period for performing no switching operations are alternately repeated.
26. The switching power supply unit of claim 6, wherein the output voltage is decreased by the voltage detection and voltage reduction circuit to reduce current fed back to an input power supply; and
operations of the first and second switching elements are intermittent oscillation operations in which an oscillation period for performing onoff switching operations and a suspension period for performing no switching operations are alternately repeated.
27. The switching power supply unit of claim 8, wherein the output voltage is decreased by the voltage detection and voltage reduction circuit to reduce current fed back to an input power supply; and
operations of the first and second switching elements are intermittent oscillation operations in which an oscillation period for performing onoff switching operations and a suspension period for performing no switching operations are alternately repeated.
28. The switching power supply unit of claim 9, wherein the output voltage is decreased by the voltage detection and voltage reduction circuit to reduce current fed back to an input power supply; and
operations of the first and second switching elements are intermittent oscillation operations in which an oscillation period for performing onoff switching operations and a suspension period for performing no switching operations are alternately repeated.
29. The switching power supply unit of claims 15, wherein the output voltage is decreased by the voltage detection and voltage reduction circuit to reduce current fed back to an input power supply; and
operations of the first and second switching elements are intermittent oscillation operations in which an oscillation period for performing onoff switching operations and a suspension period for performing no switching operations are alternately repeated.
30. The switching power supply unit of claim 1, further comprising an output stabilization circuit connected to the secondary winding of the transformer.