Voltage generating circuit, and common electrode drive circuit signal line drive circuit and gray-scale voltage generating circuit for display device

A source driver electrically connected to a capacitance load of a display body which performs a display with a charge charged in the capacitive load, the source driver comprising:

• a gray-scale voltage generating circuit out-putting a plurality of A.C. voltages at different levels;
• and
• means for outputting a voltage to the display body, the voltage being among the plurality of A.C. voltages output from the gray-scale voltage generating circuit, corresponding to image data to be displayed on the display body,
• each of the gray-scale voltage generating circuits comprising:
• a plurality of voltage generating circuits outputting A.C. voltages at different levels;
• and
• first capacitor means provided between any two of the plurality of voltage generating circuits, each of the voltage generating circuit comprising:
• two voltage sources outputting voltages at different levels;
• and
• switching means which receives voltages output from the two voltage sources and outputs one of the two voltages to the capacitance load,
• wherein one terminal of the first capacitor means is connected between either one of the two voltage sources and the switching means in one of the two voltage generating circuits and the other terminal of the first capacitor means is connected between either one of the two voltage sources and the switching means in the other of the two voltage generating circuits.

A voltage generating circuit comprising:

• a power supply for outputting a power supply signal in an A.C. waveform, the power supply signal alternately having a first period in which the power supply signal is at a first level and a second period in which the power supply signal is at a second level;
• a power supply line connected to the power supply;
• first and second charge storage elements connected to the power supply line;
• and
• first and second switching elements respectively provided between the power supply line and each of the first and second charge storage elements, wherein the first switching element connects the first charge storage element to the power supply line substantially while the second switching element disconnects the second charge storage element from the power supply line when the power supply signal is in the first period, and the second switching element connects the second charge storage element to the power supply line substantially while the first switching element disconnects the first charge storage element from the power supply line when the power supply signal is in the second period.

A voltage generating circuit for driving a liquid crystal display, the liquid crystal display including a display medium disposed between a first substrate and a second substrate, the first substrate including a plurality of pixel electrodes disposed thereon and the second substrate including a common electrode disposed thereon, the voltage generating circuit comprising:

• a power supply for outputting a power supply signal in an A.C. waveform at different levels, the power supply signal alternately having a first period in which the power supply signal is at a first level and a second period in which the power supply signal is at a second level;
• a power supply line connected to the power supply;
• a common electrode drive circuit for providing voltage for driving the common electrode;
• a common electrode supply line coupled to the common electrode drive circuit;
• a plurality of switching elements including a first switching element, a second switching element, a third switching element and a fourth switching element;
• and
• a charge storage element including a first electrode and a second electrode, the first electrode of the charge storage element coupled to the terminals of the first and second switching elements and the second electrode of the charge storage element coupled to the terminals of the third and fourth switching elements wherein, when the power supply signal is in the first period, the first switching element connects the first electrode of the charge storage element to the power supply line and the fourth switching element connects the second electrode of the charge storage element to the common electrode supply line substantially while the third switching element disconnects the second electrode of the charge storage element from the power supply line and the second switching element disconnects the first electrode of the charge storage element from the common electrode supply line, and when the power supply signal is in the second period, the third switching element connects the second electrode of the charge storage element to the power supply line and the second switching element connects the first electrode of the charge storage element to the common electrode supply line substantially while the first switching element disconnects the first electrode of the charge storage element from the power supply line and the fourth switching element disconnects the second electrode of the charge storage element from the common electrode supply line.

A voltage generating circuit comprising:

• a first power supply for outputting a first voltage in an A.C. waveform oscillating between a first level and a second level
• a power supply line connecting the first power supply to a load;
• a second, third, and fourth power supply, respectively outputting a second, third and fourth voltage at a predetermined level;
• a first and second charge storage element each having a first electrode and a second electrode, the first electrode of each of the first and second charge storage elements being coupled to the second power supply;
• a first and second switching element coupling the second electrode of the first and second charge elements respectively to the power supply line;
• a third switching element coupling the second electrode of the first charge element to the third power supply;
• and
• a fourth switching element coupling the second electrode of the second charge element to the fourth power supply;
• wherein, when the first voltage is output at the first level, the first switching element connects the first charge storage element to the power supply line and the fourth switching element connects the second storage element to the fourth power source substantially while the third switching element disconnects the first charge storage element from the third power supply and the second switching element disconnects the second charge element from the power supply line and, when the first voltage is output at the second level, the third switching element connects the first charge storage element to the third power supply and the second switching element connects the second charge storage element to the power supply line substantially while the first switching element disconnect the first charge storage element from the power supply line and the fourth switching element disconnects the second charge storage element from the fourth power supply.

A drive circuit for a display device in which pixel electrodes are provided on one of two substrates facing each other with a display body sandwiched therebetween and the common electrode forms capacitance between the common electrode and the pixel electrodes, the drive circuit comprising:

• a common electrode drive circuit including first and second different power supplies, said common electrode drive circuit outputting two kinds of voltages at different levels in a rectangular waveform to the common electrode utilizing said first and second power supplies;
• a voltage generating circuit generating a voltage at an arbitrary level between the levels of the two kinds of voltages in a rectangular waveform;
• and
• switching means for switching an output of the common electrode drive circuit to an output of the voltage generating circuit which is different than the levels of the first and second power supplies during a predetermined period in which the level of the voltage in a rectangular waveform is changed.

A drive circuit for a display device comprising:

• a gray-scale voltage drive circuit which directly outputs externally supplied gray-scale voltages or outputs interpolated voltages formed of the combination of the gray-scale voltages, thereby applying two kinds of voltages at different levels in a rectangular waveform to signal lines;
• a voltage generating circuit generating a voltage at an arbitrary level between the levels of the two kinds of voltages in a rectangular waveform;
• and
• switching means for switching an output of the gray-scale voltage drive circuit to an output of the voltage generating circuit which is different than the levels of the first and second power supplies during a predetermined period in which the level of the voltage in a rectangular waveform is changed.

A voltage generating circuit comprising:

• a plurality of power supplies, each of the plurality of power supplies respectively outputs a voltage at one of a plurality of predetermined levels, each of the respective levels of the voltages being different from each other;
• a first switching means group including a plurality of switching means which respectively receive a voltage from each respective power supply, in which the switching means is successively turned on, whereby a voltage whose level is changed from the level of the voltage from each of the respective power supply is output;
• and
• a second switching means one terminal of which is connected to an output side of the first switching means group and the other terminal of which is grounded, the second switching means being turned on only during a period including a time at which the level of the voltage, whose level is to be changed, is changed and being turned off during the other period.

A common electrode drive circuit for a display device in which pixel electrodes are provided on one of two substrates facing each other with a display body sandwiched therebetween and a common electrode, which constitutes capacitance between the common electrode and the pixel electrodes, is provided on the other substrate, for driving the common electrode, the common electrode drive circuit comprising:

• a plurality of power supplies;
• each of the plurality of power supplies respectively outputs a voltage at one of a plurality of predetermined levels, each of the respective levels of the voltages being different from each other;
• a first switching means group including a plurality of switching means which respectively receive a voltage from each respective power supply, in which the switching means is successively turned on,
• whereby a voltage whose level is changed from the level of the voltage from each of the respective power supply is output;
• and
• a second switching means one terminal of which is connected to an output side of the first switching means group and the other terminal of which is grounded, the second switching means being turned on only during a period including a time at which the level of the voltage, whose level is to be changed, is changed and being turned off during the other period.

A gray-scale voltage generating circuit for a display device in which pixel electrodes are provided on one of two substrates facing each other with a display body sandwiched therebetween, for supplying a plurality of gray-scale voltages to the pixel electrodes, based on an externally supplied digital video signal, the gray-scale voltage generating circuit comprising:

• a plurality of power supplies, each of the plurality of power supplies respectively outputs a voltage at one of a plurality of predetermined levels, each of the respective levels of the voltages being different from each other;
• a first switching means group including a plurality of switching means which respectively receive a voltage from each respective power supply, in which the switching means is successively turned on, whereby a voltage whose level is changed from the level of the voltage from each of the respective power supply is output;
• and
• a second switching means one terminal of which is connected to an output side of the first switching means group and the other terminal of which is grounded, the second switching means being turned on only during a period including a time at which the level of the voltage, whose level is to be changed, is changed and being turned off during the other period.

A drive circuit for a display device in which pixel electrodes are provided on one of two substrates facing each other with a display body sandwiched therebetween and the common electrode forms capacitance between the common electrode and the pixel electrodes, the drive circuit comprising:

• a common electrode drive circuit including first and second different power supplies, said common electrode drive circuit outputting first and second kinds of voltages at different levels in a rectangular waveform to the common electrode utilizing said first and second power supplies;
• a voltage generating circuit generating a voltage at an arbitrary level between said levels of said two kinds of voltages in a rectangular waveform;
• and
• a switching circuit system for switching an output of the common electrode drive circuit to an output of the voltage generating circuit during a predetermined period in which the level of the voltage in a rectangular waveform is changed.