Sanyo Electric Co., Ltd.

Sanjo Electric Co., Ltd.

Hisao Uehara

Mitsugu Kobayashi

Makoto Shimizu

Yusuke Tsutsui

Makoto Kitagawa

Atsuyoshi Tanioka

Makoto Fujioka

Kazuhiko Moriwaki

Yasushi Marushita

Yasuki Rai

Masahiro Okuyama

Norio Miura

Yasushi Miyajima

Kiyoshi Yoneda

Ryoichi Yokoyama

Yukinori Kuwano

Shigeru Noguchi

Shoichi Nakano

Kaneo Watanabe

Takeo Yoshimura

Noriyuki Mori

Kenji Saiki

A power supply circuit () for a display device such as a liquid crystal outputs a boosted supply voltage VDDduring normal operation, and generates a non-boosted supply voltage VDDhaving a voltage lower than that during the normal display operation by controlling the switches for switching the output within the power supply circuit () during a power save mode. The non-boosted supply voltage is supplied to the analog circuits of a driving circuit () so that the power consumption at the analog circuits is reduced. By controlling the switch for switching the output within the power supply circuit and the supply of the power supply clock, the circuit can be switched, in the power save mode, to either a mode where a lower supply voltage is generated or to a mode where the power supply is turned off.

Driving apparatus for display device

The display device of this invention, in which the retaining circuit for retaining the image signal is provided for each of the pixel elements, is capable of operating under two operation modes, a normal operation mode and a memory mode. Since the placement of the retaining circuitwhich requires relatively large area, is confined to the area for the pixel element electrodenot in between the neighboring pixel element electrodesthe required area for one pixel element is minimized, resulting in the size reduction of the liquid crystal display device. By placing at least a portion of the retaining circuit in the area of the pixel element electrodeof the neighboring pixel element, the detour of the wiring can be omitted, resulting in the efficient use of the space. By this, the area required for the retaining circuit is minimized, directly resulting in the reduction of the size of the liquid crystal display device.

Active matrix display device

Graphics are drawn with an input pen, which is provided with an optical sensor at its tip, on a display surface of an EL display. At this time, the EL display is caused to emit light in dot sequence, and the position of the input pen is detected as coordiante information on the basis of timing of light emission of the EL display and timing of light emission detection of the input pen.

Digitizing apparatus

A driving circuit of a display device such as a liquid crystal generates power supply clocks (and) based on a system clock during the normal display operation which is not a power save mode. The generated power supply clocks are supplied, directly or after inversion, to the switches (SWthrough SW(and SWthrough SW)) in a charge pump type power supply circuit () for switching the connection of capacitors (Cand C(and Cand C)) in the power supply circuit (). In this manner, supply voltages VDDand VDDwhich function as the driving power supply for a driving circuit () and a display panel () can be obtained at the power supply circuit () by boosting the input voltage Vin. The driving circuit () stops supply of the power supply clocks to the power supply circuit () when a transition to the power save mode is instructed and a power save control signal generated by a CPU I/F circuit () is changed, thereby suspending generation of the supply voltage an consumption of power consumption at the circuit and display panel.

Charge pump type power supply circuit and driving circuit for display device and display device using such power supply circuit

A liquid crystal display apparatus includes a liquid crystal display panel having preset display characteristics, such as image brightness and contrast. A luminescent unit is optically connected with the display panel and provides light to the display panel in order to form an image on the display panel. The luminescent unit includes a light collector which collects ambient light and a light source, for generating light when the amount of ambient light is insufficient to generate a clear image. A control circuit is electrically connected to the display panel and automatically varies the preset display characteristics in accordance with the amount of ambient light collected by the light collector.

Liquid crystal display apparatus having light collecting mechanism

External light is introduced by a light-introducing portion to be used as a light source for a backlight, so that the power consumption of the backlight of a liquid crystal display device can be suppressed. At the same time, the brightness of the screen of the liquid crystal display device can be increased to enhance the visibility in outdoors. Therefore, the portability of a mobile information terminal can be improved. Furthermore, the light-introducing portion covers an end portion of the main unit opposed to an axis, whereby the main unit is protected so that the life period of the mobile information terminal can be prolonged. The variety of the design of the mobile information terminal can be increased by using the transparency of the light-introducing portion.

Mobile information terminal

An improved liquid crystal display device of the type having a liquid crystal display panel, a light guide plate below a surface of the display panel and located between a reflecting portion and a diffusing portion, and a light collecting lens located at one end of the light guide plate for collecting and transmitting light to the light guide plate for providing backlight to the display panel. The display device includes a light transmitter located between the light collecting lens and the light guide plate. The light transmitter optically connects the light collecting lens and the light guide plate and separates the light collecting lens from the display panel by a predetermined difference. The light transmitter allows light to be more evenly distributed or reflected onto the display panel so that images displayed on the panel have a more uniform brightness.

Liquid crystal display having a light collecting mechanism with a light transmitter optically connected to the light guide plate and light collector for collecting ambient light

A signal driving circuit for an active matrix type display device having display pixels arranged in a matrix, comprises a signal waveform correcting circuit receiving an input pixel signal for generating a corrected output pixel signal to the display device, said signal waveform correcting circuit including a delay circuit for generating a delay signal, a difference calculating circuit for calculating a difference signal between the input pixel signal and the delay signal, and a correction circuit for generating the corrected output pixel signal based upon the difference signal and the input pixel signal, wherein a portion of the waveform amplitude of the corrected output pixel signal is formed by adjusting a corresponding portion of the waveform amplitude of the input pixel signal based upon the difference signal.

Driving circuit for display device

In the &ggr; correction circuit, a crossover point arithmetic processing unit performs arithmetic processing for each region on crossover points y in the output data direction of a &ggr; correction crossover line based on a plurality of slope data A respectively specified for each of a plurality of regions and crossover point positions X in the input data direction set in advance. A 5-to-4 encoder and a selector select one of a plurality of slope data A respectively specified for each of a plurality of regions and one result B of the results y of arithmetic processing on said crossover points based on the upper bits of input data, a flag encoder and another selector calculate the difference &Dgr;X from a crossover point position in the input data direction to the input data in the region to which input data belongs, and an arithmetic processing unit multiples the above difference &Dgr;X by the selected slope A, adds the multiplication result to the value of the selected crossover point position B in the output data direction, and outputs that value as a &ggr; correction value. Consequently, even if the number of crossover lines for digital &ggr; correction increases, arithmetic processing is simplified. When an image data processing apparatus is used, a pseudo gray scale processing circuit may be provided in a later stage of this &ggr; correction circuit to decrease the number of data bits.

Digital correction circuit and image data processing apparatus equipped with a digital correction circuit

A backlight for a liquid crystal display includes a light guide plate located adjacent to a liquid crystal display panel. A light collector is located at one end of the light guide plate and has an exposed surface for receiving ambient light. The light collector has a reflector secured inside it. The received ambient light is reflected by the reflector along the light guide plate. The reflector may include three arcuate shaped reflecting elements. The light guide plate has a reflective surface which reflects the light toward the liquid crystal display panel.

Backlight for liquid crystal displays

There is proposed is a method of controlling a flat panel display apparatus for multi-gradation display in which a data determination portion and a subfield control portion are provided. Based on a most significant bit or an upper bit of original image data, it is determined in which one of two or more divided gradation groups the original image data is included, to select a combination of subfields in accordance with a gradation-brightness characteristic of the belonging gradation group. Using a complementary relationship with human visibility, a difference in brightness between the gradations in a low-order brightness region is reduced, and a difference in brightness between the gradations in a high-order brightness region is enlarged. Therefore, a density of brightness is uniformly recognized visually over all the brightness regions, and a good quality of display can be obtained.

Method of driving flat panel display apparatus for multi-gradation

An image processing apparatus detects, in step 1, whether or not differences between currently supplied image data and image data of a previous pixel are more than a predetermined value m, and identifies a border of a computer-created image or a natural image, where a brightness level differs from the remaining area of the image, when the differences are more than the predetermined value m. Conversely, when the differences are less than the predetermined value m, the image processing apparatus checks, in step 2, whether image data at a pixel before and a pixel two before the current pixel are identical with respect to the color components constituting the color image. When the differences are not all zero, it is checked whether or not the image data at a pixel before the current pixel and the image data at the current pixel are all zero. When the image data are not identical, the color image is identified as being a natural image. When the image data are identical, the color image is identified as being a computer-created image. In step 3, the computer-created image is checked as to whether it is a 2-pixel checkered image.

Image data processing through changing error diffusing technique

A liquid crystal display (LCD) includes liquid crystal display panel located within a housing. A backlight source is detachably connected to the housing for providing light to the display panel. When the backlight source is removed from the housing, outside light, such as ambient light, provides light to the display panel. The LCD includes a light collecting lens which transmits light to the display panel and which is either covered by the backlight source or exposed to an external light source when the backlight source is detached from the housing. When the backlight source is detached, the LCD has a small size and light weight, making it convenient for carrying and using outdoors. The LCD also consumes less power when the backlight source is detached.

Liquid crystal display having detachable light source

There is provided an image information process apparatus to be applied to a display for displaying bit image display data for each pixel, for enabling the display to display continuous tones in an error diffusion manner based on P bit image data, P being larger than L. This apparatus includes a plurality of adding circuits to which a plurality of P bit image data are concurrently supplied. A predetermined lower bit of an added result at respective adding circuits is used as error data supplied to the next adjacent adding circuit. An error data holding circuit holds a predetermined lower bit of an output from an adding circuit corresponding to the last column pixel in image data supplied. It then supplies the lower bit held to an adding circuit corresponding to the top front column pixel of the image data supplied. With this arrangement, a display which is capable of displaying images based on digital data of a limited number of bits displays in a pseudo manner continuous tones expressed using a higher number of bits than the limited number. In addition, performance and processing speed of image information processing are improved.

Image information process apparatus for causing a display to display

An image information processor for a liquid crystal display by a digital driver is intended to provide image display near to a source image by making continuous-tone image display by pseudo representations. The image information processor generates L-bit image display data based on P-bit source image data, L being less than P. Added to source image data of a picture element of the Nth frame (where N is a natural number of 2 or greater) is error data corresponding to the picture element of the (N-1)th frame at the same position as the picture element of the Nth frame. The high-order L bits of the P-bit data resulting from the addition are used as image display data of the picture element of the Nth frame and at least one bit of the remaining low-order bit data is held as error data of the picture element of the Nth frame. Thus, error data of a picture element of one frame is added to the same picture element of the next frame, thereby lessening the brightness difference between both the picture elements and smoothing a time change in brightness.

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Ogaki, Japan

Hisao Uehara