Renesas Electronics Corporation

Hiroaki Shirai

Yoshiharu Hashimoto

Yoshiaki Ishizeki

Jou Kudou

A driving method of a liquid crystal display panel having a source line and a counter electrode, includes driving the counter electrode to a first potential, driving the, counter electrode to a second potential being different from the first potential, setting the counter electrode and the source line to a third potential by short-circuiting the counter electrode and the source line to an interconnection having a potential between the first potential and the second potential, and driving the source line to a potential corresponding to an image data. The setting of the counter electrode and the source line to the third potential occurs in a period of one frame.

Liquid crystal display panel driving method, liquid crystal display device, and liquid crystal display driver including driving and setting a counter electrode for common inversion driving

An impedance detection circuit includes a detection circuit, a correction circuit, a subtraction circuit, and an AC signal generator. The detection circuit has a first operational amplifier having an inverting input terminal coupled with one end of a signal line to whose other end a measured capacitor Cs is coupled, a non-inverting input terminal coupled with a shielding wire covering at least a part of the signal line and an output terminal of the AC signal generator, and an output terminal, and a second feedback resistor coupled between the output terminal and the inverting input terminal of the first operational amplifier. The correction circuit has a third resistor and a variable capacitor, and corrects a detection signal outputted from the first operational amplifier by adjusting a capacitance of the variable capacitor.

Impedance detecting circuit and impedance detection method

According to the present invention, a small impedance detection circuit capable of accurately detecting the impedance of an object to be measured and an adjustment method of an impedance detection circuit can be provided. In the impedance detection circuit according to the present invention, an AC signal generator outputs an AC signal. A detection circuit, which is connected to a circuit to be measured, applies an AC signal to the circuit to be measured. Further, the detection circuit outputs a first signal corresponding to the composite impedance of the impedance of the circuit to be measured and a parasitic impedance. A correction circuit outputs a second signal in synchronization with the first signal. A subtraction circuit outputs a detection signal obtained by subtracting the second signal from the first signal.

Impedance detection circuit and adjustment method of impedance detection circuit

A method is provided for operating a display apparatus in which one source output of a source driver is connected with first to N-th data lines through first to N-th time division switches, which method includes: driving a first pixel positioned in a first horizontal line and connected with one of the first to N-th data lines, by feeding a first drive voltage to the one of the first to N-th data lines from the one source output with associated one of the first to N-th time division switches; and driving a second pixel positioned in a second horizontal line next to the first horizontal line and connected with the one of the first to N-th data lines, by feeding a second drive voltage to the one of the first to N-th data lines from the source output with associated one of the first to N-th time division switches. The associated one time division switch is kept turned on during a time period from a start time of the driving the first pixel to a start time of the driving the second pixel.

Display panel drive technique for reducing power consumption

A driving method for driving an LCD panel having a counter electrode and a source line. In a first period, the counter electrode is driven to a potential VCOMH. In a second period, the counter electrode and the source line are short-circuited to a power supply interconnection having a power supply potential VCI. In a third period, the counter electrode is connected to a ground interconnection while the source line is kept to be short-circuited to the power supply interconnection. In a fourth period, the counter electrode is pulled down to a potential VCOML lower than a ground potential In a fifth period, the source line is driven to a potential corresponding to an image data while the counter electrode is kept to the potential VCOML. The electric power consumed in pulling down the counter electrode from a positive potential to a negative potential can be effectively reduced.

Liquid crystal display panel, common inversion driving method, liquid crystal display device, and liquid crystal display driver

A display apparatus includes a display panel; and a data driver configured to output drive voltages from a plurality of output nodes to drive the display panel. The data driver includes a plurality of output amplifiers, each of which is configured to receive a gradation voltage corresponding to a pixel data and to output the drive voltage in response to the gradation voltage; and a driver-side demultiplexer configured to connect the plurality of output amplifiers to selection output nodes selected from among the plurality of output nodes. The display panel includes a plurality of data lines; and a panel-side demultiplexer configured to connect selection data lines selected from among the plurality of data lines with the plurality of output nodes.

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Kanagawa, Japan

Hiroaki Shirai