1. A discharge sustain driver circuit for a plasma display device, the driver circuit comprising:
a first transistor switching circuit for switching a DC bus voltage across the plasma display device;
a storage capacitance;
at least one inductor; and
first and second bi-directional switching circuits coupled in series and being coupled to the first switching circuit to transfer charge from the plasma display device through the at least one inductor to the storage capacitance, and back to the plasma display device; and
a controller for the bi-directional switching circuits to control the bi-directional switching circuits so as to receive the charge on the storage capacitance and return the charge in an opposite charge direction to the plasma display device.
2. The discharge sustain driver circuit of claim 1, wherein the first transistor switching circuit comprises a full bridge transistor switching circuit.
3. The discharge sustain driver circuit of claim 1, wherein the storage capacitance comprises a single storage capacitor or a plurality of parallel connected storage capacitors.
4. The discharge sustain driver circuit of claim 1, wherein the bi-directional switching circuits each include a current sensor and each turn off when current through the switching circuit is approximately zero.
5. The discharge sustain driver circuit of claim 1, wherein each bi-directional switching circuit comprises two series connected semiconductor switches that are turned on substantially simultaneously.
6. The discharge sustain driver circuit of claim 5, further comprising a current sensor in series with the semiconductor switches.
7. The discharge sustain driver circuit of claim 6, wherein the current sensor comprises a resistor.
8. The discharge sustain driver circuit of claim 1, wherein the at least one inductor comprises first and second inductors in series with both bidirectional switches, and the storage capacitance is connected in parallel with a series connection of one bidirectional switch and the second inductor.
9. The discharge sustain driver circuit of claim 1, wherein the at least one inductor is connected in a series circuit with the storage capacitance, and the series circuit of the storage capacitance and at least one inductor is connected in parallel with one of the bidirectional switches.
10. The discharge sustain driver circuit of claim 2, wherein the full bridge switching circuit comprises first and second series connected transistors connected across the DC bus and third and fourth series connected transistors connected across the DC bus; wherein the first and third transistors are high side connected and the second and fourth are low side connected;
the plasma display device being connected across a common connection of the first and second transistors and a common connection of the third and fourth transistors, and wherein the first and second bi-directional switches are coupled in series together and in series with first and second inductors, the storage capacitance being connected across a series connection of the second bidirectional switch and the second inductor;
the circuit operating according to the steps comprising:
turning on the first and fourth transistors to charge the display device substantially to the bus voltage;
turning off the first and fourth transistors when the display device has charged to substantially the bus voltage;
turning on the first bidirectional switch to transfer the charge on the display device to the storage capacitance;
turning off the first bi-directional switch when the charge transfer is substantially complete;
turning on the second bi-directional switch to reverse the charge across the storage capacitance;
turning off the second bi-directional switch when the current in the second bi-directional switch is substantially zero;
turning on the first bi-directional switch to transfer the reverse charge on the storage capacitance to the display device;
turning on the second and third transistors to further charge the display device substantially to the bus voltage in the reverse direction;
turning off the second and third transistors when the display device has charged to substantially the bus voltage;
turning on the first bi-directional switch to transfer charge from the display device to the storage capacitance;
turning on the second bi-directional switch to reverse the charge across the storage capacitance;
turning off the second bi-directional switch when the current in the second bi-directional switch is substantially zero; and
turning on the first bi-directional switch to transfer the again reversed charge on the storage capacitance to the display device; and repeating the above steps as long as desired to sustain a discharge in the display device.
11. The circuit of claim 10, wherein the bidirectional switches automatically turn off when the current through the respective switch is substantially zero.
12. The circuit of claim 10, wherein all transistors are MOSFETs and the bidirectional switches employ MOSFETs.
13. The circuit of claim 2, wherein the full bridge switching circuit comprises first and second series connected transistors connected across the DC bus and third and fourth series connected transistors connected across the DC bus; wherein the first and third transistors are high side connected and the second and fourth are low side connected;
the plasma display device being connected across a common connection of the first and second transistors and a common connection of the third and fourth transistors, and wherein the first and second bi-directional switches are coupled in series together, and wherein the storage capacitance and the at least one inductor are coupled in a series circuit across the second bi-directional switch;
the circuit operating according to the steps comprising:
turning on the first and fourth transistors to substantially charge the display device to the bus voltage;
turning off the first and fourth transistors when the display device has charged to substantially the bus voltage;
turning on the first bi-directional switch to transfer the charge on the display device to the storage capacitance;
turning off the first bi-directional switch when the current through the switch is substantially zero;
turning on the second bidirectional switch to reverse the charge across the storage capacitance;
turning off the second bi-directional switch when the current therethrough is substantially zero;
turning on the first bi-directional switch to transfer the reverse charge on the storage capacitance to the display device;
turning on the second and third transistors to fully charge the display device to substantially the bus voltage in the reverse direction;
turning off the second and third transistors when the display device has charged to substantially the bus voltage;
turning on the first bi-directional switch to transfer the reverse charge on the display device to the storage capacitance;
turning off the first bi-directional switch when the current through the switch is substantially zero;
turning on the second bi-directional switch to again reverse the charge across the storage capacitance;
turning off the second bi-directional switch when the current therethrough is substantially zero;
turning on the first bi-directional switch to transfer the charge on the storage capacitance to the display device; and
repeating the above steps as long as desired to sustain a discharge in the display device.
14. The circuit of claim 13, wherein the bi-directional switches automatically turn off when the current through the respective switch is substantially zero.
15. The circuit of claim 13, wherein all transistors are MOSFETs and the bi-directional switches employ MOSFETs.
16. The circuit of claim 1, wherein the first and second bidirectional switching circuits each comprise:
first and second semiconductor switching devices;
a current sensor connected in series with the switching devices, thereby forming a series circuit;
a driver circuit controlling the onoff operation of the first and second switching devices such that the first and second switching devices are substantially simultaneously turned on and off, the driver circuit turning the first and second switching devices on in response to a control input and turning the first and second switching devices off when current in the current sensor substantially drops to near a zero current.
17. The circuit of claim 1, wherein the first and second bi-directional switching circuits each comprise:
at least one semiconductor switching device;
a current sensor connected in series with the switching device, thereby forming a series circuit;
a driver circuit controlling the onoff operation of the at least one switching device, the driver circuit turning the switching device on in response to a control input and turning the switching device off when current in the current sensor substantially drops to near a zero current.
18. A discharge sustain driver circuit for a plasma display device, the driver circuit comprising:
a first transistor switching circuit for switching a DC bus voltage across the plasma display device;
a storage capacitance;
at least one inductor; and
first and second bi-directional switching circuits coupled in series and being coupled to the first switching circuit to transfer charge from the plasma display device trough the at least one inductor to the storage capacitance, and back to the plasma display device; and
a controller for the switching circuits to control the switching circuits so as to receive the charge on the storage capacitance and return the charge in an opposite charge direction to the plasma display device, the first and second bi-directional switching circuits turning off when a substantially zero current flows through the respective bi-directional switching circuit.
19. A discharge sustain driver circuit for a plasma display device, the driver circuit comprising:
a first transistor switching circuit for switching a DC bus voltage across the plasma display device;
a storage capacitance;
at least one inductor; and
first and second bidirectional switching circuits coupled in series and being coupled to the first switching circuit to transfer charge from the plasma display device through the at least one inductor to the storage capacitance, and back to the plasma display device; and
a controller for the bi-directional switching circuits to control the bi-directional switching circuits so as to receive the charge on the storage capacitance and return the charge in an opposite charge direction to the plasma display device, further wherein the storage capacitance comprises a single storage capacitor or a plurality of parallel connected storage capacitors.
20. A method of operating a discharge sustain driver circuit for a plasma display device, the driver circuit comprising a first transistor switching circuit for switching a DC bus voltage across the plasma display device, a storage capacitance, at least one inductor; and first and second bi-directional switching circuits coupled in series and being coupled to the first switching circuit to transfer charge from the plasma display device through the at least one inductor to the storage capacitance, and back to the plasma display device; and a controller for the bi-directional switching circuits to control the bidirectional switching circuits so as to receive the charge on the storage capacitance and return the charge in an opposite charge direction to the plasma display device and wherein the first switching circuit comprises a full bridge switching circuit, the full bridge switching circuit comprising first and second series connected transistors connected across the DC bus and third and fourth series connected transistors connected across the DC bus; wherein the first and third transistors are high side connected and the second and fourth are low side connected; the plasma display device being connected across a common connection of the first and second transistors and a common connection of the third and fourth transistors, and wherein the first and second bi-directional switches are coupled in series together and in series with first and second inductors, the storage capacitance being connected across a series connection of the second bi-directional switch and the second inductor;
the method comprising:
turning on the first and fourth transistors to charge the display device to substantially the bus voltage;
turning off the first and fourth transistors when the display device has charged to substantially the bus voltage;
turning on the first bi-directional switch to transfer the charge on the display device to the storage capacitance;
turning off the first bi-directional switch when the charge transfer is substantially complete;
turning on the second bi-directional switch to reverse the charge across the storage capacitance;
turning off the second bi-directional switch when the current in the second bi-directional switch is substantially zero;
turning on the first bi-directional switch to transfer the reverse charge on the storage capacitance to the display device;
turning on the second and third transistors to further charge the display device substantially to the bus voltage in the reverse direction;
turning off the second and third transistors when the display device has charged to substantially the bus voltage;
turning on the first bidirectional switch to transfer charge from the display device to the storage capacitance;
turning on the second bi-directional switch to reverse the charge across the storage capacitance;
turning off the second bi-directional switch when the current in the second bi-directional switch is substantially zero; and
turning on the first bi-directional switch to transfer the again reversed charge on the storage capacitance to the display device; and repeating the above steps as long as desired to sustain a discharge in the display device.
21. The method of claim 20, wherein the bi-directional switches automatically turn off when the current through the respective switch is substantially zero.
22. A method of operating a discharge sustain driver circuit for a plasma display device, the driver circuit comprising a first transistor switching circuit for switching a DC bus voltage across the plasma display device, a storage capacitance, at least one inductor; and first and second bi-directional switching circuits coupled in series and being coupled to the first switching circuit to transfer charge from the plasma display device through the at least one inductance to the storage capacitor, and back to the plasma display device, and a controller for the bi-directional switching circuits to control the bi-directional switching circuits so as to receive the charge on the storage capacitance and return the charge in an opposite charge direction to the plasma display device; and wherein the first switching comprises a full bridge switching circuit, the full bridge switching circuit comprising first and second series connected transistors connected across the DC bus and third and fourth series connected transistors connected across the DC bus; wherein the first and third transistors are high side connected and the second and fourth are low side connected; the plasma display device being connected across a common connection of the first and second transistors and a common connection of the third and fourth transistors, and wherein the first and second bi-directional switches are coupled in series together, and wherein the storage capacitance and the at least one inductor are coupled in a series circuit across the second bi-directional switch;
the method comprising:
turning on the first and fourth transistors to substantially charge the display device to the bus voltage;
turning off the first and fourth transistors when the display device has changed to substantially the bus voltage;
turning on the first bi-directional switch to transfer the charge on the display device to the storage capacitance;
turning off the first bi-directional switch when the current through the switch is substantially zero;
turning on the second bi-directional switch to reverse the charge across the storage capacitance;
turning off the second bi-directional switch when the current therethrough is substantially zero;
turning on the first bi-directional switch to transfer the reverse charge on the storage capacitance to the display device;
turning on the second and third transistors to fully charge the display device to substantially the bus voltage in the reverse direction;
turning off the second and third transistors when the display device has charged to substantially the bus voltage;
turning on the first bi-directional switch to transfer the reverse charge on the display device to the storage capacitance;
turning off the first bi-directional switch when the current through the switch is substantially zero;
turning on the second bi-directional switch to again reverse the charge across the storage capacitance;
turning off the second bi-directional switch when the current therethrough is substantially zero;
turning on the first bi-directional switch to transfer the charge on the storage capacitance to the display device; and
repeating the above steps as long as desired to sustain a discharge in the display device.
23. The method of claim 22, wherein the bi-directional switches automatically turn off when the current through the respective switch is substantially zero.
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 cambering vehicle comprising:
an elongate front column having a longitudinal axis;
a bracket assembly attached to said front column by a pivot shaft;
a first pivot axle and a second pivot axle adjacent said bracket;
a first trailing arm pivotally attached to said first pivot axle;
a second trailing arm pivotally attached to said second pivot axle; and,
first and second rear wheels associated with said first and second trailing arms;
wherein said steering column may be rotated away from said bracket about said pivot shaft and toward said first and second trailing arms to place said cambering vehicle in a folded position.
2. The cambering vehicle of claim 1, wherein said steering column may be rotated about said pivot shaft toward said bracket to place said cambering vehicle in a working position.
3. The cambering vehicle of claim 2, further comprising a latching mechanism attached to said bracket to secure said bracket to said column in said working position.
4. The cambering vehicle of claim 3, wherein said latching mechanism comprises a spring loaded latch.
5. The cambering vehicle of claim 3, wherein said bracket further comprises an aperture therethrough, said latching mechanism further comprising a spring-loaded shaft capable of fitting within said aperture to releaseably connect said bracket to said steering column.
6. The cambering vehicle of claim 1, wherein said first and said second pivot axles are inclined from an imaginary line perpendicular to said longitudinal axis of said front column.