Author: claimsbot

1. A process for preparing 4-aminodiphenylamine comprising
reacting nitrobenzene and aniline in presence of a complex base catalyst for condensation reaction to form a reaction mixture comprising 4-nitrodiphenylamine and 4-nitrosodiphenylamine;
hydrogenating the reaction mixture in presence of hydrogen, a powdery composite catalyst, and a hydrogenation solvent to obtain a hydrogenation reaction product;
separating, recovering, and reusing the complex base catalyst and the powdery composite catalyst from the hydrogenation reaction product;
separating, recovering, and reusing aniline, and optionally water, from the hydrogenation reaction product;
refining the hydrogenation reaction product to obtain 4-aminodiphenylamine,
wherein the complex base catalyst comprises tetraalkyl ammonium hydroxide, alkali metal hydroxide or oxide, and tetraalkyl ammonium salt, the powdery composite catalyst comprises nickel, aluminum, and a component A that is at least one selected from the group consisting of Fe, Cu, Co, Mn, Cr, Mo, B and P.
2. The process according to claim 1, wherein the condensation reaction is carried out under conditions of a molar ratio of nitrobenzene to aniline of from 1:1 to 1:15, a reaction temperature of from 20 to 150\xb0 C., a reaction pressure of from 0.005 to 0.1 MPa (absolute pressure), and a reaction time of from 3.5 to 6 hours.
3. The process according to claim 1, wherein a molar ratio of hydroxide ion in the complex base catalyst to nitrobenzene is in a range of from 1:4 to 4:1.
4. The process according to claim 1, wherein a molar ratio of tetraalkyl ammonium hydroxide to alkali metal hydroxide or oxide to tetraalkyl ammonium salt in the complex base catalyst equals (0-9):(0.5-3):(0.5-3).
5. The process according to claim 1, wherein an amount of total concentration of tetraalkyl ammonium hydroxide, alkali metal hydroxide or oxide, and tetraalkyl ammonium salt in the reaction mixture is in a range from 10 to 100 percent by weight.
6. The process according to claim 1, wherein the complex base catalyst is prepared by stirring tetraalkyl ammonium hydroxide, alkali metal hydroxide or oxide, and tetraalkyl ammonium salt, in a solid or aqueous solution form, in water at a temperature of from 0 to 90\xb0 C. until being homogeneous to form an aqueous form of the complex base catalysts.
7. The process according to claim 6, wherein the aqueous form of the complex base catalyst is treated through azeotropic process by adding benzene to completely remove water and form an anhydrous form of the complex base catalysts.
8. The process according to claim 1, wherein the tetraalkyl ammonium salt is represented by a formula of
(R1)(R2)(R3)(R4)N+nXn\u2212
wherein R1, R2, R3 and R4, identical or different, respectively, is an alkyl having from 1 to 4 carbon atoms and said alkyl being optionally substituted by a hydrophilic substitute; Xn\u2212 is selected from the group consisting of halide ion, sulfate radical, carbonate radical, phosphate radical, bicarbonate radical, bisulfate radical, C1-C2-alkyl carbonate radical, and C1-C2-alkyl sulfate radical; n is a value of from 1 to 2.
9. The process according to claim 8, wherein in the formula of the tetraalkyl ammonium salt, at least one of R1, R2, R3 and R4 is substituted by a hydrophilic substitute selected from the group consisting of hydroxy, methoxy, polyether, cationic polyamide, polyester, polyethylene polyamine, and highly water-soluble quaternary ammonium salt-containing radical.
10. The process according to claim 9, wherein the tetraalkyl ammonium salt is a hydrophilic substituent-carring tetraalkyl ammonium salt selected from the group consisting of poly-methylated triethylene tetraamine sulfate, poly-methylated diethylene triamine carbonate, N,N-dimethyl-N,N-bis(methoxyethyl)ammonium carbonate, N-methyl-N,N,N-tri(methoxyethyl)ammonium carbonate, N,N,N-trimethyl-N-hydroxyethyl ammonium carbonate, trimethyl hydroxyethyl ammonium chloride, N,N,N-trimethyl-N-ethoxylated (1-4 moles of ethylene oxide)ethyl ammonium carbonate, N,N,N-trimethyl-N-ethoxylated (1-4 moles of ethylene oxide)propyl ammonium carbonate, N,N,N-trimethyl-N-ethoxylated (1-4 moles of ethylene oxide)propyl ammonium chloride, and N,N-dimethyl-N,N-bis(ethoxylated (1-4 moles of ethylene oxide)propyl)ammonium carbonate.
11. The process according to claim 8, wherein the tetraalkyl ammonium salt is selected from the group consisting of tetramethyl ammonium carbonate, tetramethyl ammonium methyl-carbonate, tetraethyl ammonium carbonate, tetraethyl ammonium ethyl-carbonate, tetramethyl ammonium sulfate, tetramethyl ammonium methyl-sulfate, tetraethyl ammonium sulfate, and tetraethyl ammonium ethyl-sulfate.
12. The process according to claim 8, wherein the tetraalkyl ammonium salt is prepared by reacting trialkyl amine with di(C1-C2)alkyl carbonate or di(C1-C2)alkyl sulfate in a polar solvent.
13. The process according to claim 12, wherein the reaction for preparing the tetraalkyl ammonium salt is carried out under a reaction pressure of from 0.1 to 3.0 MPa, a reaction temperature of from 50-200\xb0 C., reaction time ranges from 1.5 to 6 hours, a molar ratio of trialkyl amine to di(C1-C2)alkyl carbonate or di(C1-C2)alkyl sulfate of from 2:1 to 1:2, and
wherein the polar solvent is methanol, ethanol, or isopropanol, and the polar solvent is in an amount of from 1 to 10 times of weight of the trialkyl amine.
14. The process according to claim 1, wherein the condensation reaction is carried out in the absence of oxygen.
15. The process according to claim 1, wherein it is unnecessary to add or control proton materials during the condensation reaction.
16. The process according to claim 1, wherein the condensation reaction is carried out without a solvent.
17. The process according to claim 1, wherein the complex base catalyst is added during an initial stage of the condensation reaction, and tetraalkyl ammonium salt and alkali metal hydroxide or oxide are replenished during the condensation reaction.
18. The process according to claim 1, wherein the condensation reaction is conducted in a circulating system comprising a condensing circulating pump, a falling film reactor, and a first reactor.
19. The process according to claim 18, wherein the falling film reactor uses ethanol vapor, hot water, steam, or methanol vapor as heat medium.
20. The process according to claim 1, wherein hydrogen gas is used as reducing agent for hydrogenating the reaction mixture;
wherein the hydrogenation reaction is carried out at a volume ratio of hydrogen gas to a sum of the hydrogenation solvent and the reaction mixture in a range of from 10:1 to 1500:1, a weight ratio of the powdery composite catalyst to the sum of the hydrogenation solvent and the reaction mixture in a range of from 0.5:100 to 16:100, and a weight ratio of the hydrogenation solvent to the reaction mixture in a range of from 1:10 to 5:10; and
wherein a reaction temperature of the hydrogenation reaction ranges from 50 to 100\xb0 C., a reaction pressure of the hydrogenation reaction ranges from 0.2 to 3.0 MPa (absolute pressure), and the reaction time ranges from 2 to 7 hours.
21. The process according to claim 1, wherein the powdery composite catalyst comprises nickel in a range of from 25 to 99.9 wt %, and a total amount of aluminum and the component A in a range of from 0.1 to 75 wt %.
22. The process according to claim 1, wherein the powdery composite catalyst is at least partially regenerated.
23. The process according to claim 1, wherein the powdery composite catalyst is prepared by
mixing powdery nickel, powdery aluminum, and component A to form a mixture,
melting the mixture at an elevated temperature,
discharging and quenching the mixture,
pulverizing the discharged and quenched mixture into powder, and
treating the powder with an aqueous solution of a hydroxide.
24. The process according to claim 1, wherein a magnetic separator is used to recover the powdery composite catalyst based on the magnetism thereof following the hydrogenation reaction.
25. The process according to claim 24, wherein the recovered powdery composite catalyst is conveyed back to hydrogenation reactor via a Venturi type mixed solid-liquid conveying equipment utilizing feeding power.
26. The process according to claim 1, wherein deactivated powdery composite catalyst is regenerated by treating with ultrasonic vibration andor strong base.
27. The process according to claim 1, wherein the hydrogenation solvent is an alcohol, water, or a mixture of alcohol and water.
28. The process according to claim 1, wherein the hydrogenation reaction product is extracted with a water-based extracting agent comprising a polyether as a co-extracting agent, a volume ratio of the extracting agent to the hydrogenation reaction product is in a range of from 0.5:1 to 5:1, and an extracting time is in a range of from 2 to 5 hours.
29. The process according to claim 28, wherein the polyether co-extracting agent is selected from the group consisting of polyethylene glycol ether, polypropylene glycol ether, fatty alcohol polyethenoxy ether, and a mixture thereof, and a volume ratio of the polyether co-extracting agent to the water-based extracting agent ranges from 0.0001:1 to 0.005:1.
30. The process according to claim 1, wherein an aqueous phase obtained by extracting the hydrogenation reaction product is concentrated by a one-stage or multi-stage gas-aid falling film evaporators to recover the complex base catalyst.
31. The process according to claim 30, wherein the gas-aid falling film evaporator includes a shell pass, a tube pass, a steam inlet installed on a top of the shell pass, a condensed water outlet installed at a bottom of the shell pass, a lower concentration aqueous phase inlet installed on a top of the tube pass, a higher concentration aqueous phase outlet installed at a bottom of the tube pass, a pair of flow-aiding steam inlets installed on a top of the tube pass, and a distributing tray installed at below the lower concentration aqueous phase inlet.
32. The process according to claim 30, wherein inside the falling film evaporator, a system pressure ranges from 0.005 to 0.1 MPa (absolute pressure), residence time ranges from 2 to 60 seconds, and a pressure of flow-aiding steam is maintained in a range of from 0.01 to 0.5 MPa during the concentration of the aqueous phase.
33. The process according to claim 1, wherein refining is performed through a three-column continuous rectification and batch rectification, and
wherein the rectification column 1, rectification column 2, and rectification column 3 are operated at a vacuum degree ranging independently from 0.09 to 0.098 MPa; a still temperature of from 260 to 290\xb0 C., from 260 to 300\xb0 C. and from 120 to 170\xb0 C., respectively; a reflux ratio of from 2:1 to 10:1, from 1:0.5 to 1:4 and from 1:0.5 to 1:2, respectively; and the batch rectification column is operated at a vacuum degree of from 0.09 to 0.098 MPa, and a still temperature of from 280 to 330\xb0 C.
34. A process for preparing 4-aminodiphenylamine comprising:
(i) continuously feeding nitrobenzene, aniline, and a complex base catalyst to a condensation process stage reactor via metering pumps, and allowing to react to form a condensation liquid comprising 4-nitrodiphenylamine, 4-nitrosodiphenylamine, and salts thereof;
(ii) continuously feeding the condensation liquid and a hydrogenation solvent, including supplementary hydrogenation solvent and optionally recovered hydrogenation solvent, to a hydrogenation process stage reactor, and allowing to react with hydrogen gas under a powdery composite catalyst, including supplementary powdery composite catalyst and reused, optionally regenerated, powdery composite catalyst, to form a hydrogenation liquid containing 4-aminodiphenylamine;
(iii) feeding the hydrogenation liquid to separation I process stage reactor, where the powdery composite catalyst, which is to be recycled back to the hydrogenation process stage directly or after being at least partially regenerated, the complex base catalyst, which is to be recycled back to the condensation process stage, and an aqueous phase obtained by evaporation during concentration and organic phase obtained by extraction are obtained;
(iv) feeding separately aqueous phase and organic phase obtained in separation I process stage reactor to separation II process stage reactor, where aniline, which is to be recycled back to the condensation process stage reactor, crude 4-aminodiphenylamine from which most aniline has been separated, and optionally, the hydrogenation solvent, which is to be recycled back to the hydrogenation process stage, are obtained; and
(v) feeding crude 4-aminodiphenylamine to a refining process stage reactor, where partial aniline, which is to be recycled back to the condensation process stage, and refined 4-aminodiphenylamine are obtained.

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 method of making a flexible printed circuit board (FPC) which comprises a substrate comprising a first metal foil layer, a second metal foil layer, a first intervening layer interleaved the first and second metal foil layers, a second intervening layer covered on the second metal foil layer, and a third metal foil layer covered on other side of the second intervening layer, the method comprising:
(a) laminating the substrate;
(b) adhering a covering film to outermost surfaces of the substrate;
(c) defining a hole in one side of the substrate through the covering film and the first and second metal foil layers and the first intervening layer and an additional hole in an opposite side of the substrate through the second and third metal foil layer and the second intervening layer; and
(d) plating a portion of an inner wall of the hole and the additional hole with a conductive material to form a via to electrically connect the at least two metal foil layers.
2. The method as claimed in claim 1, further comprising removing the covering film from the substrate.
3. The method as claimed in claim 1, wherein the hole is defined by etching or laser technology.
4. The method as claimed in claim 1, wherein the covering film is made of insulative plastic.
5. The method as claimed in claim 1, wherein the first intervening layer comprises two insulating layers and an adhesive layer adhering the insulating layers together.
6. The method as claimed in claim 1, wherein the second intervening layer comprises an insulating layer and an adhesive layer to adhere the insulating layer to the second metal foil layer.

That claimed is:

1. A user-actuated ignition and powering system for starting and sustaining the operative functioning of an internal combustion engine in a vehicle and powering at least one electronic control unit positioned to control a predetermined function associated with the operation or use of the vehicle, the user-actuated ignition and powering system comprising:
a starter responsive to the user and having an electrically driven motor to crank the engine;
a capacitor electrically connected to the starter to provide power to drive the motor of the starter and thereby enable the starter to crank the engine;
an alternator mechanically connected to the engine and electrically connected to the capacitor to convert mechanical energy generated by the engine when the engine is operatively functioning into electrical energy to provide power to the capacitor for maintaining the stored energy of the capacitor substantially at or above a first predetermined level;
power delivery controller connected to the capacitor and responsive to the alternator for controlling power delivery to and from the capacitor by permitting power to be delivered from the capacitor to the starter when the starter is engaged to crank the engine, permitting power to be delivered to the capacitor from the alternator when the alternator is operatively generating electrical current such that the stored energy of the capacitor is maintained at or above the predetermined level, and electrically isolating the capacitor from the at least one electronic control unit to thereby prevent discharge of power from the capacitor to the electrical system of the vehicle;
a voltage enhancer electrically connected to the capacitor and responsive to the power delivery controller to enhance voltage between the capacitor and the alternator when the alternator is operatively generating electrical current to thereby increase the power delivered from the alternator to the capacitor;
at least one battery electrically connected to the at least one electronic control unit of the vehicle to provide power to the electronic control unit and electrically connected to the alternator to receive power from the alternator to thereby maintain the energy of the battery substantially at or above a second predetermined level; and
a power delivery control override responsive to a user and electrically connected to each of the power delivery controller and the capacitor to override the power delivery controller and provide power to the electronic control unit from the capacitor.
2. A system as defined in claim 1, wherein capacitor has at least eleven cells to readily provide a voltage greater than about fourteen and six-tenths volts (14.6 V).
3. A system as defined in claim 2, wherein the capacitor provides at least fifteen volts (15.0 V) during normal operating conditions to thereby generate more than six kilowatts (6 kW) of power to the starter.
4. A system as defined in claim 3, wherein the power delivery controller comprises a switch responsive to an electrical signal supplied by the alternator when the alternator is generating electrical current, the switch being operatively responsive to the electrical signal by closing an open connection along a current path between the alternator and the capacitor to thereby permit power to be delivered to the capacitor from the alternator when the alternator is generating electrical current such that the stored energy of the capacitor is maintained substantially at or above the predetermined level.
5. A system as defined in claim 4, wherein the switch comprises at least one of a transistor or a magnetic switch.
6. A system as defined in claim 5, wherein the voltage enhancer comprises a step-up converter electrically connected to the capacitor and the power delivery controller to step-up the voltage between the capacitor and the alternator to thereby ensure that the voltage is at least about fifteen volts (15.0 V) and less than about seventeen and eight-tenths volts (17.8 V) during normal operating conditions as power is delivered to the capacitor when the starter is disengaged and the alternator is operatively generating electrical current.
7. A user-actuated ignition system for starting an internal combustion engine in a vehicle, the system comprising:
a starter responsive to the user and having an electrically driven motor to crank the engine;
a capacitor electrically connected to the starter to provide electric power for driving the motor of the starter and thereby enabling the starter to crank the engine;
an alternator mechanically connected to the engine and electrically connected to the capacitor to convert mechanical energy generated by the engine when the engine is operatively functioning into electrical energy to provide power to the capacitor for maintaining the stored energy of the capacitor substantially at or above a predetermined level; and
a power delivery controller connected to the capacitor and responsive to the alternator for controlling power delivery to and from the capacitor by permitting power to be delivered from the capacitor to the starter when the starter is engaged to crank the engine and permitting power to be delivered to the capacitor from the alternator when the alternator is operatively generating electrical current such that the stored energy of the capacitor is maintained at or above the predetermined level.
8. A system as defined in claim 7, wherein the capacitor provides at least about fifteen volts (15.0 V) during normal operating conditions to thereby generate more than about six kilowatts of power (6 kW) to the starter.
9. A system as defined in claim 8, wherein the capacitor has at least eleven cells to thereby readily provide a voltage greater than 14.6 volts during normal operating conditions
10. A system as defined in claim 9, further comprising a voltage enhancer electrically connected to the capacitor and to the alternator to enhance the voltage between the capacitor and the alternator to thereby increase the power delivered from the alternator to the capacitor when the alternator is operatively generating electrical current.
11. A system as defined in claim 10, wherein the voltage enhancer comprises a step-up converter electrically connected to the capacitor to step-up the voltage between the capacitor and alternator to thereby ensure that the voltage is at least about fifteen volts (15.0 V) and less than about seventeen and eight-tenths volts (17.8 V) during normal operating conditions as power is delivered to the capacitor when the starter is disengaged and the alternator is operatively generating electrical current.
12. A system as defined in claim 7, wherein the power delivery controller comprises a switch responsive to an electrical signal supplied by the alternator when the alternator is generating electrical current, the switch being operatively responsive to the electrical signal by closing an open connection along a current path between the alternator and the capacitor to thereby permit power to be delivered to the capacitor from the alternator when the alternator is generating electrical current such that the stored energy of the capacitor is maintained substantially at or above the predetermined level.
13. A system as defined in claim 12, wherein the switch comprises at least one of a transistor or a magnetic switch.
14. A user-actuated ignition system for starting an internal combustion engine in a vehicle, the system comprising:
a starter responsive to the user and having an electrically driven motor to crank the engine;
an alternator; and
an n-celled capacitor electrically connected to the starter to provide power for driving the motor of the starter and thereby enabling the starter to crank the engine and to the alternator for receiving power from the alternator when the alternator is generating electrical current, the number of cells, n, corresponding to the amount of power delivered to the starter by the capacitor and the amount of power delivered from the alternator to the capacitor.
15. A system as defined in claim 14, wherein the (10i)th cell, i1, provides an incremental power increase of greater than about one and ninety six hundredths (1.96) times the product of the capacitance, C, of the capacitor and the total number of cells, n.
16. A system as defined in claim 15, wherein power, p, is determined by the product 0.98 times the capacitance of the capacitor times the square of the number of cells employed in the system, according to the formula p0.98(C) (n2)watts, where C is the capacitance of the capacitor and n is the number of cells.
17. An internal combustion engine starting system comprising:
a starter to crank the engine when engaged;
an alternator mechanically connected to the engine to convert mechanical energy generated by the engine when the engine is operatively functioning into electrical energy;
a capacitor electrically connected to each of the starter and the alternator to provide power to the starter and receive power from the alternator, the capacitor having at least eleven cells which readily provides a voltage greater than 14.6 volts during normal operating conditions; and
a power delivery controller electrically connected to the capacitor and responsive the starter to prevent power from being delivered by the capacitor to the starter and permit power to be delivered to the capacitor from the alternator when the starter is disengaged and the alternator is operatively generating electrical current such that the energy level of the capacitor is maintained within a predetermined range while permitting power to be delivered to the starter when the starter is engaged.
18. A system as defined in claim 17, wherein the capacitor provides at least fifteen volts (15.0 V) under normal operating conditions to thereby generate more than six kilowatts of power (6 kW) to the starter.
19. A system as defined in claim 17, wherein the power deliver controller comprises a transistor responsive to an electrical signal supplied by the alternator when the alternator is generating electrical current, the transistor closing in response to the electrical system to permit power to be delivered to the capacitor from the alternator when the starter is disengaged and the alternator is operatively generating electrical current such that the energy level of the capacitor is maintained within a predetermined range.
20. A system as defined in claim 19, wherein the power delivery controller comprises a magnetic switch responsive to an electrical signal supplied by the alternator when the alternator is generating electrical current, the magnetic switch closing in response to the electrical system to permit power to be delivered to the capacitor from the alternator when the starter is disengaged and the alternator is operatively generating electrical current such that the energy level of the capacitor is maintained within a predetermined range.
21. A method for selectively providing power to an electrical system associated with an internal combustion engine connected to a starter, an alternator, and a battery, the method comprising:
supplying power from a capacitor to the starter when the engine is being started, the capacitor having at least eleven cells to thereby readily provide a voltage greater than 14.6 volts during normal operating conditions;
preventing delivery of power from the capacitor to the electrical system when the engine is not being started; and
providing power from the alternator to the enhanced-power capacitor when the engine is running.
22. A method as defined in claim 21, wherein the step of supplying power to the starter comprises generating more than six kilowatts of power (6 kW) to the starter by providing a voltage with the enhanced-power capacitor of at least fifteen volts (15.0 V) under normal operating conditions.
23. A method as defined in claim 21, wherein the step of providing power from the alternator to the capacitor when the engine is running comprises providing a closed conductive path between the alternator and the capacitor, the path being established in response to a current generated by the alternator.
24. A method as defined in claim 23, wherein the step of providing power from the alternator to the capacitor comprises providing a capacitor having a voltage level sufficient to deliver enough power to the starter to crank the engine and be recharged directly by the alternator.
25. A method as defined in claim 24, wherein the step of providing power from the alternator to the capacitor comprises providing a capacitor having n cells wherein each cell provides an incremental increase in power of the product one and ninety six hundredths times the capacitance of the capacitor, C, and the number of cells, n, as represented by the expression 1.96(C)(n).
26. A method as defined in claim 23, wherein the step of providing power from the alternator to the capacitor further comprises stepping-up the voltage between the capacitor and the alternator such that the voltage is at least about fifteen volts (15 V) and less than about 17.8 volts (17.8 V).
27. A method as defined in claim 23, wherein the step of preventing delivery of power from the capacitor to the electrical system comprises electrically isolating the capacitor from the electrical system.
28. A method as defined in claim 27, wherein the step of preventing delivery of power by isolating the enhanced-power capacitor comprises providing a transistor that is connected to the enhanced-power capacitor and that provides an open electrical connection when the engine is not running.
29. A method as defined in claim 27, wherein the step of preventing delivery of power by isolating the enhanced-power capacitor comprises providing a magnetic switch that is connected to the enhanced-power capacitor and that provides an open electrical connection when the engine is not running.
30. A method as defined in claim 21, further comprising selectively supplying power from the capacitor to the electrical system.
31. A method as defined in claim 30, wherein the step of selectively supplying power from the capacitor to the electrical system is performed when the power available to the electrical system from the battery is insufficient to perform a function otherwise powered by the electrical system.

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 normally black mode liquid crystal display device that performs monochrome gradation display, the liquid crystal display device comprising:
a liquid crystal panel including a plurality of pixels, each constituted by a plurality of subpixels whose transmittances can be controlled independently of each other;
a gradation converting unit that converts a gradation of each pixel included in an input video signal to gradations of a plurality of subpixels; and
a drive circuit that drives the liquid crystal panel based on a video signal obtained by the gradation converting unit, wherein
characteristics of the gradation conversion by the gradation converting unit are obtained by performing, in a case where the gradation of the pixel can be represented by only one minimum-area subpixel, a process in which with setting gradations of other subpixels to their minimum gradations, a gradation of the minimum-area subpixel is determined, and by performing, in other cases, one of a first process in which one subpixel is selected as a first subpixel, and with setting gradations of other subpixels to their maximum gradations or minimum gradations, a gradation of the first subpixel is determined so that a ratio of a transmittance of the first subpixel to a transmittance of the pixel is less than a limit value, and when the gradation of the first subpixel cannot be determined to satisfy the condition regarding the transmittances, a plurality of subpixels are selected as second subpixels, and with setting a gradation of a remaining subpixel to its maximum gradation or minimum gradation, gradations of the second subpixels are determined to obtain a gradation higher than or equal to the gradation of the pixel; a second process in which the gradation of the first subpixel is determined with changing the gradations set to other subpixels; and a third process in which one subpixel different from the first subpixel is selected as a third subpixel, and with setting gradations of other subpixels to their maximum gradations or minimum gradations, a gradation of the third subpixel is determined.
2. The liquid crystal display device according to claim 1, wherein each pixel of the liquid crystal panel is constituted by a plurality of subpixels having equal areas.
3. The liquid crystal display device according to claim 2, wherein each pixel of the liquid crystal panel is constituted by three subpixels with an area ratio of 1:1:1.
4. The liquid crystal display device according to claim 1, wherein each pixel of the liquid crystal panel is constituted by a plurality of subpixels including subpixels having different areas.
5. The liquid crystal display device according to claim 4, wherein each pixel of the liquid crystal panel is constituted by three subpixels with an area ratio of 1:2:2.
6. The liquid crystal display device according to claim 1, wherein each pixel of the liquid crystal panel is constituted by a plurality of subpixels having different areas.
7. The liquid crystal display device according to claim 6, wherein each pixel of the liquid crystal panel is constituted by three subpixels with an area ratio of 1:2:3.
8. The liquid crystal display device according to claim 1, wherein the gradation converting unit includes a lookup table, and converts a gradation of a pixel into gradations of a plurality of subpixels using the look up table.
9. The liquid crystal display device according to claim 8, wherein the gradation converting unit includes a plurality of look up tables in association with a plurality of gamma characteristics, and converts a gradation of a pixel into gradations of a plurality of subpixels using a look up table selected from the plurality of look up tables.
10. The liquid crystal display device according to claim 1, wherein the limit value is a value of 0.1 or less.
11. The liquid crystal display device according to claim 1, wherein the limit value is a value of 0.05 or less.
12. The liquid crystal display device according to claim 1, wherein the liquid crystal panel is a vertical alignment-type liquid crystal panel.
13. A method of driving a normally black mode liquid crystal display device that has a liquid crystal panel including a plurality of pixels, each constituted by a plurality of subpixels whose transmittances are controlled independently of each other, and that performs monochrome gradation display, the method comprising the steps of:
converting a gradation of each pixel included in an input video signal to gradations of a plurality of subpixels; and
driving the liquid crystal panel based on an obtained video signal, wherein
characteristics of the gradation conversion in the step of performing the gradation conversion are obtained by performing, in a case where the gradation of the pixel can be represented by only one minimum-area subpixel, a process in which with setting gradations of other subpixels to their minimum gradations, a gradation of the minimum-area subpixel is determined, and by performing, in other cases, one of a first process in which one subpixel is selected as a first subpixel, and with setting gradations of other subpixels to their maximum gradations or minimum gradations, a gradation of the first subpixel is determined so that a ratio of a transmittance of the first subpixel to a transmittance of the pixel is less than a limit value, and when the gradation of the first subpixel cannot be determined to satisfy the condition regarding the transmittances, a plurality of subpixels are selected as second subpixels, and with setting a gradation of a remaining subpixel to its maximum gradation or minimum gradation, gradations of the second subpixels are determined to obtain a gradation higher than or equal to the gradation of the pixel; a second process in which the gradation of the first subpixel is determined with changing the gradations set to other subpixels; and a third process in which one subpixel different from the first subpixel is selected as a third subpixel, and with setting gradations of other subpixels to their maximum gradations or minimum gradations, a gradation of the third subpixel is determined.