1. A switching voltage controlling circuit that is adapted to a liquid crystal display (LCD), the LCD comprising a display panel and a plurality of gate drivers, the display panel comprising a plurality of pixel units, the switching voltage controlling circuit comprising:
a current-controlled switch, having a first terminal and a second terminal, the first terminal being coupled to a constant voltage;
a transmission line, having a first terminal and a second terminal, the first terminal being coupled to the second terminal of the current-controlled switch, the transmission line being serially coupled to the gate drivers, wherein the gate drivers generate a switching voltage according to a voltage provided by the transmission line and control the pixel units; and
a feedback circuit, coupled to the transmission line and the current-controlled switch, the feedback circuit regulating an amount of a current passing through the current-controlled switch according to a voltage difference between the first terminal and the second terminal of the transmission line.
2. The switching voltage controlling circuit as claimed in claim 1, wherein the current-controlled switch is a transistor operated in an active region.
3. The switching voltage controlling circuit as claimed in claim 1, wherein the feedback circuit comprises: a first amplifier, a first input terminal and a second input terminal of the first amplifier being coupled to the first terminal and the second terminal of the transmission line, respectively;
a first voltage dividing resistor, a first terminal of the first voltage dividing resistor being coupled to an output terminal of the first amplifier;
a second voltage dividing resistor, a first terminal and a second terminal of the second voltage dividing resistor being coupled to a second terminal of the first voltage dividing resistor and a first voltage, respectively; and
a second amplifier, a first input terminal and a second input terminal of the second amplifier being coupled to the second terminal of the first voltage dividing resistor and a second voltage, an output terminal of the second amplifier outputting a control voltage for regulating the amount of the current passing through the current-controlled switch.
4. The switching voltage controlling circuit as claimed in claim 3, wherein the first voltage is a ground voltage, and the second voltage is greater than the first voltage.
5. A liquid crystal display (LCD), comprising:
a display panel, comprising a plurality of pixel units;
a plurality of gate drivers, coupled to the pixel units;
a current-controlled switch, having a first terminal and a second terminal, the first terminal of the current-controlled switch being coupled to a constant voltage;
a transmission line, a first terminal of the transmission line being coupled to the second terminal of the current-controlled switch, the transmission line being serially coupled to the gate drivers, wherein the gate drivers generate a switching voltage according to a voltage provided by the transmission line and control the pixel units; and
a feedback circuit, coupled to the transmission line and the current-controlled switch, the feedback circuit regulating an amount of a current passing through the current-controlled switch according to a voltage difference between the first terminal and a second terminal of the transmission line.
6. The LCD as claimed in claim 5, wherein the current-controlled switch is a transistor operated in an active region.
7. The LCD as claimed in claim 5, wherein the feedback circuit comprises:
a first amplifier, a first input terminal and a second input terminal of the first amplifier being coupled to the first terminal and the second terminal of the transmission line, respectively;
a first voltage dividing resistor, a first terminal of the first voltage dividing resistor being coupled to an output terminal of the first amplifier;
a second voltage dividing resistor, a first terminal and a second terminal of the second voltage dividing resistor being coupled to a second terminal of the first voltage dividing resistor and a first voltage, respectively; and
a second amplifier, a first input terminal and a second input terminal of the second amplifier being coupled to the second terminal of the first voltage dividing resistor and a second voltage, an output terminal of the second amplifier outputting a control voltage for regulating the amount of the current passing through the current-controlled switch.
8. The LCD as claimed in claim 7, wherein the first voltage is a ground voltage, and the second voltage is greater than the first voltage.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1-18. (canceled)
19. A process for producing polyolefins, comprising the steps of:
polymerizing at least one olefin monomer to obtain a reaction mixture;
separating at least a part of the reaction mixture to obtain a separated portion;
dividing the separated portion of the reaction mixture into a polymer-lean fraction and a polymer-rich fraction;
subjecting at least a part of the polymer-lean fraction to a purification step to obtain a purified polymer-lean fraction;
recycling at least a part of the purified polymer-lean fraction back into the polymerizing step of the at least one olefin monomer; wherein
the polymerizing step comprises slurry polymerization; and
the polymer-lean fraction is in liquid form or in a super critical state.
20. The process according to claim 19, wherein
the subjecting of the at least a part of the polymer-lean fraction to a purification step and the recycling of the at least a part of the purified polymer-lean fraction comprise:
dividing the polymer-lean fraction into a first and a second stream;
recycling the first stream to the polymerizing step of the at least one olefin monomer;
purifying the second stream; and
recycling at least a part of the purified second stream back to the polymerizing step of the at least one olefin monomer.
21. The process according to claim 19, wherein the subjecting of the at least a part of the polymer-lean fraction to a purification step comprises removing impurities contained in the polymer-lean fraction; and
the reaction mixture comprises at least 50% by mole of hydrocarbons having from 1 to 4 carbon atoms.
22. The process according to claim 19, wherein the purification step is carried out by conducting at least one flashing step.
23. The process according to claim 19, wherein the purification step is carried out by conducting at least one distillation step.
24. The process according to claim 19, wherein the step of dividing the separated portion of the reaction mixture is carried out in a hydrocyclone or a screen.
25. The process according to claim 20, wherein the step of dividing the polymer-lean fraction is carried out in a hydrocyclone or a screen.
26. The process according to claim 19, wherein the polymer-lean fraction comprises at least one selected from the group consisting of: olefin oligomers, metal components, unreacted monomer, and byproducts formed during the polymerizing step.
27. The process according to claim 26, wherein the byproducts comprise at least one selected from the group consisting of ketones, aldehydes, sulphur-containing compounds, and alcohols.
28. The process according to claim 19, further comprising:
mixing the polymer-rich fraction with fresh olefin monomer to obtain a second mixture; and
dividing the second mixture into a second polymer-rich fraction and a monomer-rich fraction.
29. The process according to claim 28, further comprising recycling the monomer-rich fraction to the polymerizing step of the at least one olefin monomer.
30. The process according to claim 20, wherein the dividing of the polymer-lean fraction comprises dividing 10 to 95 wt % of the polymer-lean fraction into the second stream.
31. The process according to claim 19, wherein the separating at least a part of the reaction mixture is carried out continuously.
32. The process according to claim 19, wherein the separating at least a part of the reaction mixture is carried out intermittently.
33. The process according to claim 19, wherein the separating at least a part of the reaction mixture comprises concentrating a polymer in the reaction mixture to obtain another mixture and separating at least a part of the another mixture to obtain the separated portion.
34. The process according to claim 33, wherein the concentrating is carried out by a settling leg.
35. The process according to claim 19, wherein a concentration of a polymer in the reaction mixture is from 30 to 60% by weight.
36. The process according to claim 19, wherein the polymerizing step is carried out in a stirred tank reactor or loop reactor.