Seiko Instruments Inc

Fujio Matsu

Shuhei Yamamoto

Masafumi Hoshino

Hiroyuki Fujita

Hirotomo Oniwa

Teruo Ebihara

Kentaro Yagi

A display device includes a liquid crystal panel, a controller, a common driver and a segment driver. The common driver is powered by a high power supply voltage and outputs row driving waveforms having predetermined voltage levels, which are relatively high. The segment driver is powered by a low power supply voltage and outputs column driving waveforms having predetermined voltage levels, which are relatively low. By this construction, it is not necessary for both the segment and common drivers to be high withstand voltage integrated circuit devices.

Display device

A liquid crystal display panel gray shade driving device comprises first circuitry for applying row signals represented by a set of orthonormal functions to a group of row electrodes throughout one frame by set sequential scanning for each of selecting periods, and second circuitry for sequentially carrying out a dot product computation between the set of orthonormal functions and a set of pixel data consisting of bits, and applying a column signal having a voltage level corresponding to a result of the computation to each of a group of column electrodes in synchronization with the set sequential scanning for each of the selecting periods. The first circuitry has a vertical driver for applying the row signal, by doubling the rate thereof, to the group of row electrodes and repeating the same set sequential scanning at least for two frames of previous and subsequent frames. The second circuitry has a frame memory for holding the pixel data in each frame while dividing it according to a significance of each bit and a dot product computing circuit for reading out the set of held pixel data per significance of each bit and carrying out the dot product computation to generate a column signal component corresponding to the significance of each bit. A horizontal driver divides the column signal components into a significant bit component and a less significant bit component, and distributes one component to the previous frame and the other to the subsequent frame to generate a column signal which is applied to the group of column electrodes.

Gray shade driving device of liquid crystal display

A display device includes a vertical driver for applying to row electrodes a set of row signals represented by a set of orthogonal functions supplied by an orthogonal function generator at each selection period by group-sequential scanning within one frame. A dot product processor successively carries out a dot product computation between the set of orthogonal functions and a set of pixel data. A horizontal driver applies to column electrodes column signals having voltage levels determined by the results of the dot product computation at each selection period in synchronization with the group-sequential scanning. A frame memory stores the pixel data for each frame in divided bit form. The dot product processor reads out the set of stored pixel data in divided bit form and executes the dot product computation to produce a column signal component for each respective bit. The horizontal driver arranges a plurality of column signal components corresponding to the respective bits subjected to either pulse modulation or frame-rate modulation within one frame period to produce the column signal that is applied to the column electrodes. A memory controller controls the writing of the pixel data into the frame memory. Bit data subjected to the pulse modulation are written to the frame memory for every frame, while bit data subjected to frame-rate modulation are selectively written to the frame memory only at frames specified by the frame-rate modulation.

Gradative driving apparatus of liquid crystal display panel

In order to prevent signal distortion using a multiple line selection driving technique when using pulse width modulation to achieve a half-tone display in a liquid crystal display panel, respective bits of column signals are arranged in a descending pulse width order and a voltage generating circuit is used to lower level differences in adjacent bits. An orthonormal function generating circuit generates a plurality of row signals to drive a group of row electrodes through a vertical driver. A dot product computation circuit computes a dot product of the orthonormal functions and pixel display data to generate a column signal in the above manner. A horizontal driver applies the column signal to a group of column electrodes. Pixel data is stored in a frame memory, each datum being represented by a series of bits corresponding to a gray scale. The dot product computation circuit divides the pixel data into the respective bits, and individually carries out the dot product computation for each bit. The horizontal driver arranges the column signal components in order of descending pulse width. A voltage level circuit lowers the voltage level between the column components to reduce distortion caused by the high switching speed between the components and the low response time of the liquid crystal material.

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Chiba, Japan

Fujio Matsu