1. Device for extracting at least one gas contained in drilling mud of the type comprising:
an enclosure;
means for conveying the drilling mud into the enclosure;
means for removing the drilling mud from the enclosure;
means for admitting a carrier gas into the enclosure comprising a carrier gas admission pipe, connecting a source of carrier gas to the enclosure, the admission pipe being equipped with a regulating device for regulating the flow of carrier gas circulating in the pipe, and
a gas extraction pipe opening into the enclosure via a gas extraction opening;
characterised in that the means for admitting the carrier gas comprise:
a sensor for measuring an instantaneous pressure which is substantially identical to the pressure inside the enclosure at a point located downstream of the regulating device; and
means for controlling the regulating device which are connected to the sensor in order to control the flow of carrier gas injected into the enclosure via the regulating device at any moment in time as a function of the difference between the pressure measured by the sensor and a specified gas extraction pressure.
2. Device according to claim 1, characterised in that the sensor is located upstream of the extraction opening.
3. Device according to either claim 1, characterised in that the sensor is located in the carrier gas admission pipe.
4. Device according to claim 1, characterised in that the sensor is located in the extraction pipe.
5. Device according to claim 4, characterised in that the extraction pipe comprises a flow regulator, the sensor being located upstream of the flow regulator.
6. Device according to claim 1, characterised in that the regulating device is located close to the enclosure, the admission pipe comprising a downstream section of a length which is greater than zero located between the enclosure and the regulating device.
7. Device according to claim 1, characterised in that the control means comprise means for calculating the difference between the specified extraction pressure and the pressure measured by the sensor, means for comparing the calculated difference from a threshold error value and means for controlling the regulating device as a function of the result obtained by the comparison means.
8. Device according to claim 7, characterised in that the threshold error value is less than 2 mbar.
9. Device according to claim 1, characterised in that the admission pipe comprises a flowmeter.
10. Device according to claim 1, characterised in that the gas extraction pipe is connected downstream to suction means.
11. Assembly for analysing the gases contained in drilling mud, characterised in that it comprises:
an extraction device according to any of the preceding claims;
means for sampling drilling mud which are connected to the transfer means and
analysis means connected to the extraction pipe.
12. Method for extracting at least one gas contained in drilling mud of the type comprising the following stages:
conveying the drilling mud into an enclosure;
admission of a carrier gas into the enclosure via an admission pipe, this admission including regulation of the flow of carrier gas admitted into the enclosure by a regulating device,
gas extraction from the enclosure via an extraction pipe opening in the enclosure via a gas extraction opening, and
removal of the drilling mud from the enclosure;
characterised in that the admission stage comprises:
instantaneous measurement of a pressure substantially equal to the pressure prevailing in the enclosure, at a point located downstream of the regulating device, and
at any moment in time, control of the flow of carrier gas injected into the enclosure through the regulating device as a function of the difference between the pressure measured and a specified gas extraction pressure.
13. Process according to claim 12, characterised in that control of the carrier gas flow comprises the following stages:
calculation of the difference between the specified extraction pressure and the pressure measured by the sensor,
comparison of the calculated difference from a threshold error value; and
control of the regulating device as a function of the result obtained by the said comparison.
14. Process according to claim 13, characterised in that the threshold error value is less than 2 mbar.
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 liquid crystal display device, comprising:
first and second substrates facing each other and including a plurality of pixel regions, each of the plurality of pixel regions including transmissive and reflective areas;
a plurality of first electric field distorting units repeatedly arranged in the transmissive area, wherein each of the plurality of first electric field distorting units generates a first domain structure;
a plurality of second electric field distorting units repeatedly arranged in the reflective area, wherein each of the plurality of second electric field distorting units generates a second domain structure having less domains than the first domain structure; and
a liquid crystal layer interposed between the first and second substrates,
wherein the plurality of second electric field distorting units have one of a reversed-T shape, a T shape and an inclined T shape.
2. The device according to claim 1, wherein the first domain structure includes four domains.
3. The device according to claim 2, wherein the second domain structure includes two domains.
4. The device according to claim 3, wherein liquid crystal molecules in the liquid crystal layer of the two domains have different orientational directors from each other about 90 degrees.
5. The device according to claim 1, wherein the plurality of first electric field distorting units have two cross shapes combined with each other.
6. The device according to claim 1, wherein the transmissive area includes a plurality of first regions, each including the first electric field distorting unit, and the reflective area includes a plurality of second regions, each including the second electric field distorting unit, and wherein the first region has a same area as the second region.
7. The device according to claim 6, wherein an area of disclination between domains in the second domain structure is less than an area of disclination between domains in the first domain structure.
8. The device according to claim 1, wherein each of the first and second electric field distorting units includes one of a rib shape and a slit shape.
9. The device according to claim 1, wherein each of the first and second electric field distorting units is formed on one of the first and second substrates.
10. The device according to claim 1, wherein the reflective area surrounds the transmissive area.
11. The device according to claim 1, wherein the plurality of first electric field distorting units and the plurality of second electric field distorting units are arranged in a column direction.
12. The device according to claim 1, further comprising:
gate and data lines on the first substrate and crossing each other to define the plurality of pixel regions;
a plurality of thin film transistors connected to the gate and data lines;
a plurality of reflectors corresponding to the reflective area;
a plurality of pixel electrodes connected to the plurality of thin film transistors and corresponding the transmissive area; and
a common electrode on the second substrate.
13. The device according to claim 12, wherein the plurality of reflectors are electrically connected to the plurality of pixel electrodes.
14. The device according to claim 12, further comprising a passivation layer interposed between the plurality of reflectors and the plurality of pixel electrodes.