1. A method comprising:
receiving one or more signals from a switching power converter;
processing the one or more signals to determine an approximate secondary-side conduction time delay that begins when at least one of the signals indicates cessation of primary-side current conduction in a transformer of the switching power converter and ends when conduction begins in a secondary-side current in the transformer;
determining the secondary-side current conduction time utilizing the secondary-side conduction time delay;
determining an approximate amount of charge transferred to the secondary-side of the transformer using the determined secondary-side current conduction time; and
generating a current control signal to control power delivered to a load coupled to the switching power converter based on the determined approximate amount of charge transferred to the secondary-side of the transformer.
2. The method of claim 1 wherein determining the approximate secondary-side conduction time delay further comprises:
sensing a signal representing a secondary-side voltage of a transformer of the switching power converter; and
based on at least one value of the sensed signal, determining the approximate secondary-side conduction time delay.
3. The method of claim 2 wherein the transformer further includes an auxiliary secondary-side winding, and the signal representing the secondary-side voltage of a transformer of the switching power converter comprises an auxiliary voltage across the auxiliary secondary-side winding.
4. The method of claim 3 wherein the value of the sensed signal represents a zero crossing of the auxiliary voltage and determining the approximate secondary-side conduction time delay comprises:
determining an elapsed time between cessation of the primary-side current conduction until sensing the zero crossing of the auxiliary voltage; and
determining the approximate secondary-side conduction time delay using the determined elapsed time.
5. The method of claim 4 wherein determining the approximate secondary-side conduction time delay using the determined elapsed time comprises:
multiplying the elapsed time by a value greater than one to determine the approximate secondary-side conduction time delay.
6. The method of claim 3 wherein the value of the sensed signal represents a zero crossing of the auxiliary voltage and determining the approximate secondary-side conduction time delay comprises:
determining a first elapsed time from when a pulse of a current control signal for the switching power converter ends that coincides with cessation of the primary-side current conduction and when a zero crossing detection signal received by the controller indicates a zero crossing of the auxiliary voltage;
determining a second elapsed time between the end of the first elapsed time cessation of the primary-side current conduction until determining that a first mathematical derivative of the auxiliary voltage is zero; and
adding the first and second elapsed times to determine the approximate secondary-side conduction time delay.
7. The method of claim 1 wherein determining the approximate secondary-side conduction time delay further comprises:
sensing a signal representing a drain voltage of a current control switch coupled to the primary-side of the transformer to control current in the primary-side;
processing the sensed signal representing the drain voltage to determine an elapsed time between cessation of the primary-side current conduction and when a first mathematical derivative of the signal equals zero; and
determining the approximate secondary-side conduction time delay using the determined elapsed time.
8. The method of claim 1 further comprising:
generating a control signal to turn the switch \u201cOFF\u201d;
determining a resonant period TRES of a secondary-side voltage;
detecting zero crossings of the secondary-side voltage;
determining an estimated secondary-side current conduction time period T2EST; wherein T2EST equals an elapsed time from when the switch turns \u201cOFF\u201d and detection of a second zero crossing of the secondary-side voltage; and
determining the approximate secondary-side transformer current conduction time to equal T2EST\u2212TRES4\u2212the secondary-side conduction time delay.
9. The method of claim 1 wherein the control switch is a field effect transistor (FET) coupled between a primary-side winding of the transformer and a reference voltage and determining the approximate secondary-side conduction time delay comprises:
sensing a drain voltage of the FET;
determining a first derivative of the drain voltage; and
determining the approximate secondary-side conduction time delay from when the FET is turned \u201cOFF\u201d until the first derivative of the drain voltage equals zero.
10. The method of claim 1 wherein the control switch is a field effect transistor (FET) coupled between a primary-side winding of the transformer and a reference voltage and determining the approximate secondary-side conduction time delay comprises:
generating a control signal to turn the FET \u201cOFF\u201d at a time t0;
detecting a zero crossing of a signal representing a voltage on a secondary-side of the transformer, wherein the detected zero crossing occurs at a time t1;
determining an elapsed time period Td1 wherein Td1=t1\u2212t0;
determining an elapsed time period Td2 from t1 until a drain voltage of the FET reaches a maximum value during the cycle of the FET; and
determining the approximate secondary-side conduction time delay equal to Td1+Td2.
11. The method of claim 10 further comprising:
generate a control signal to turn the switch \u201cOFF\u201d;
determining a resonant period TRES of a secondary-side voltage;
detecting zero crossings of the secondary-side voltage;
determining an estimated secondary-side current conduction time period T2EST; wherein T2EST equals an elapsed time from when the switch turns \u201cOFF\u201d and detection of a second zero crossing of the secondary-side voltage; and
determining the approximate secondary-side transformer current conduction time to equal T2EST\u2212TRES4\u2212Td1\u2212Td2.
12. The method of claim 1 wherein the load comprises one or more light emitting diodes.
13. The method of claim 1 wherein cessation of the primary-side current conduction in the transformer until conduction begins in a secondary-side current in the transformer occurs during a single cycle of a control switch that controls current in the flyback-type switching power converter.
14. The method of claim 1 wherein the switching power converter is a flyback-type switching power converter.
15. The method of claim 1 wherein:
the switching power converter includes a field effect transistor (FET) to control primary-side current conduction;
receiving one or more signals from the switching power converter comprises receiving a signal representing a gate voltage of the FET; and
processing the one or more signals to determine an approximate secondary-side conduction time delay comprises processing the signal representing the gate voltage of the FET to determine the approximate secondary-side conduction time delay.
16. An apparatus comprising:
a controller configured to:
receive one or more signals from a switching power converter;
process the one or more signals to determine an approximate secondary-side conduction time delay that begins when at least one of the signals indicates cessation of primary-side current conduction in a transformer of the switching power converter and ends when conduction begins in a secondary-side current in the transformer;
determine the secondary-side current conduction time utilizing the secondary-side conduction time delay;
determine an approximate amount of charge transferred to the secondary-side of the transformer using the determined secondary-side current conduction time; and
generate a current control signal to control power delivered to a load coupled to the switching power converter based on the determined approximate amount of charge transferred to the secondary-side of the transformer.
17. The apparatus of claim 16 wherein to determine the approximate secondary-side conduction time delay, the controller is further configured to:
sense a signal representing a secondary-side voltage of a transformer of the switching power converter; and
based on at least one value of the sensed signal, determine the approximate secondary-side conduction time delay.
18. The apparatus of claim 17 wherein the transformer further includes an auxiliary secondary-side winding, and the signal representing the secondary-side voltage of a transformer of the switching power converter comprises an auxiliary voltage across the auxiliary secondary-side winding.
19. The apparatus of claim 18 wherein the value of the sensed signal represents a zero crossing of the auxiliary voltage and to determine the approximate secondary-side conduction time delay the controller is further configured to:
determine an elapsed time between cessation of the primary-side current conduction until sensing the zero crossing of the auxiliary voltage; and
determine the approximate secondary-side conduction time delay using the determined elapsed time.
20. The apparatus of claim 19 wherein to determine the approximate secondary-side conduction time delay using the determined elapsed time the controller is further configured to:
multiply the elapsed time by a value greater than one to determine the approximate secondary-side conduction time delay.
21. The apparatus of claim 18 wherein the value of the sensed signal represents a zero crossing of the auxiliary voltage and to determine the approximate secondary-side conduction time delay, the controller is further configured to:
determine a first elapsed time from when a pulse of a current control signal for the switching power converter ends that coincides with cessation of the primary-side current conduction and when a zero crossing detection signal received by the controller indicates a zero crossing of the auxiliary voltage;
determine a second elapsed time between the end of the first elapsed time cessation of the primary-side current conduction until determining that a first mathematical derivative of the auxiliary voltage is zero; and
add the first and second elapsed times to determine the approximate secondary-side conduction time delay.
22. The apparatus of claim 16 wherein to determine the approximate secondary-side conduction time delay, the controller is further configured to:
sense a signal representing a drain voltage of a current control switch coupled to the primary-side of the transformer to control current in the primary-side;
process the sensed signal representing the drain voltage to determine an elapsed time between cessation of the primary-side current conduction and when a first mathematical derivative of the signal equals zero; and
determine the approximate secondary-side conduction time delay using the determined elapsed time.
23. The apparatus of claim 16 the controller is further configured to:
generate a control signal to turn the switch \u201cOFF\u201d;
determine a resonant period TRES of a secondary-side voltage;
detect zero crossings of the secondary-side voltage;
determine an estimated secondary-side current conduction time period T2EST, wherein T2EST equals an elapsed time from when the switch turns \u201cOFF\u201d and detection of a second zero crossing of the secondary-side voltage; and
determine the approximate secondary-side transformer current conduction time to equal T2EST\u2212TRES4\u2212the secondary-side conduction time delay.
24. The apparatus of claim 16 wherein the control switch is a field effect transistor (FET) coupled between a primary-side winding of the transformer and a reference voltage and to determine the approximate secondary-side conduction time delay, the controller is further configured to:
sense a drain voltage of the FET;
determine a first derivative of the drain voltage; and
determine the approximate secondary-side conduction time delay from when the FET is turned \u201cOFF\u201d until the first derivative of the drain voltage equals zero.
25. The apparatus of claim 16 wherein the control switch is a field effect transistor (FET) coupled between a primary-side winding of the transformer and a reference voltage and to determine the approximate secondary-side conduction time delay the controller is further configured to:
generate a control signal to turn the FET \u201cOFF\u201d at a time t0;
detect a zero crossing of a signal representing a voltage on a secondary-side of the transformer, wherein the detected zero crossing occurs at a time t1;
determine an elapsed time period Td1 wherein Td1=t1\u2212t0;
determine an elapsed time period Td2 from t1 until a drain voltage of the FET reaches a maximum value during the cycle of the FET; and
determine the approximate secondary-side conduction time delay equal to Td1+Td2.
26. The apparatus of claim 25 the controller is further configured to:
generate a control signal to turn the switch \u201cOFF\u201d;
determine a resonant period TRES of a secondary-side voltage;
detect zero crossings of the secondary-side voltage;
determine an estimated secondary-side current conduction time period T2EST, wherein T2EST equals an elapsed time from when the switch turns \u201cOFF\u201d and detection of a second zero crossing of the secondary-side voltage; and
determine the approximate secondary-side transformer current conduction time to equal T2EST\u2212TRES4\u2212Td1\u2212Td2.
27. The apparatus of claim 16 wherein the load comprises one or more light emitting diodes.
28. The apparatus of claim 16 wherein cessation of the primary-side current conduction in the transformer until conduction begins in a secondary-side current in the transformer occurs during a single cycle of a control switch that controls current in the flyback-type switching power converter.
29. The apparatus of claim 16 wherein the controller comprises an integrated circuit.
30. The apparatus of claim 16 wherein the switching power converter is a flyback-type switching power converter.
31. The apparatus of claim 16 wherein the switching power converter include a field effect transistor (FET) to control primary-side current conduction and the one or more signals from the switching power converter comprises a signal representing a gate voltage of the FET, and the controller is further configured to:
process the one or more signals to determine an approximate secondary-side conduction time delay comprises processing the signal representing the gate voltage of the FET to determine the approximate secondary-side conduction time delay.
32. A lamp comprising:
a switching power converter;
a load coupled to the switching power converter; and
a controller coupled to the switching power converter to control the switching power converter, wherein the controller is configured to:
receive one or more signals from the switching power converter;
process the one or more signals to determine an approximate secondary-side conduction time delay that occurs from cessation of primary-side current conduction in a transformer of the switching power converter until conduction begins in a secondary-side current in the transformer;
determine the secondary-side current conduction time utilizing the secondary-side conduction time delay;
determine an approximate amount of charge transferred to the secondary-side of the transformer using the determined secondary-side current conduction time; and
generate a current control signal to control power delivered to a load coupled to the switching power converter based on the determined approximate amount of charge transferred to the secondary-side of the transformer.
33. The lamp of claim 32 wherein the load comprises one or more light emitting diodes.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A printer comprising:
a printing medium feed reel that feeds a printing medium;
a ribbon feed reel that feeds an ink ribbon;
a platen roller that conveys the printing medium that is fed from said printing medium feed reel and the ink ribbon that is fed from said ribbon feed reel;
a thermal head that is disposed opposite said platen roller via the printing medium and the ink ribbon and performs printing by transferring ink of the ink ribbon onto the printing medium;
a ribbon conveying roller for conveying the ink ribbon that has been used for printing;
a ribbon take-up reel that takes up the ink ribbon that is conveyed by said ribbon conveying roller;
a motor that drives said platen roller;
a rotary drive mechanism that transmits a drive power of said motor to said ribbon conveying roller via at least a first belt and transmits a drive power of said motor to said ribbon take-up reel via at least the first belt and a second belt; and
a tension unit comprising a plurality of pulleys that are in contact at least with said first belt and second belt and rotate following the movement thereof, a plurality of elastic members that adjust positions of said plurality of pulleys so as to apply tension at least to said first belt and second belt and a plurality of fixing members that fix the positions of said plurality of pulleys.
2. The printer according to claim 1, wherein said plurality of pulleys comprise: a first pulley that is in contact with said first belt, rotates following the movement thereof, and transmits the drive power transmitted from said first belt to said second belt; and a second pulley that is in contact with said second belt and rotates following the movement thereof.
3. The printer according to claim 1, wherein said tension unit further comprises a base material and a plurality of support members that are slidably attached to said base material and rotatably support said plurality of pulleys; said plurality of elastic members comprise a plurality of coil springs that bias said plurality of support members in a predetermined direction; and said plurality of fixing members comprise a plurality of screws for fixing said plurality of support members to said base material.