Renesas Technology Corp.

Hitachi, Ltd.

Renesas Electronics Corporation

Lapis Semiconductor Co., Ltd.

Hitachi Displays, Ltd.

Hiroki Aizawa

Yasuyuki Kudo

Akihito Akai

Kazunari Kurokawa

Kazuo Ookado

Kazuo Okado

Hiroyoshi Ichikura

Takeshi Nosaka

Toshimitsu Matsudo

Takuya Eriguchi

A display driving device comprising: a high supply voltage operation unit that generates an operating current under application of a high supply voltage so as to supply driving voltages to a display panel; a low supply voltage operation unit that operates under the application of a low supply voltage lower than the high supply voltage and controls the high supply voltage operation unit; and a reuse circuit that receives the operating current from the high supply voltage operation unit and supplies the operating current to a ground side via the low supply voltage operation unit so as to apply the low supply voltage to the low supply voltage operation unit.

Display driving device

A display driver includes a data fetching unit that fetches first to Nth pixel data pieces corresponding to luminance levels of respective pixels and outputs the same at a timing of an edge of a clock signal, first to Nth amplifiers that amplify first to Nth gradation voltages corresponding to the first to Nth pixel data piece to obtain first to Nth driving voltages, and a bias voltage generation unit that generates and supplies bias voltages for setting current values of operation currents to the respective amplifiers. The bias voltage generation unit stores a first value and a second value of the bias voltage used for setting the current value to a higher value and a lower value, and generates a bias voltage having the first value during a period from the timing of the edge of the clock signal, and switches the voltage value to the second value thereafter.

Display driver and semiconductor device comprising display driver

A liquid crystal display system including: a liquid crystal display panel for displaying image data; a semiconductor device including a display driving circuit configured to drive the liquid crystal display panel, said display driving circuit having a function of generating gray scale voltages based on a gamma characteristic curve, said display driving circuit including: an interface circuit coupled to plurality of external terminals for inputting a first, second and third value which define the gamma characteristic curve; a first register configured to store the first value that adjusts an amplitude of the gamma characteristic curve; a second register configured to store the second value that adjusts a gradient of the gamma characteristic curve; a third register configured to store the third value making a micro adjustment of the gamma characteristic curve; and a generation circuit configured to generate the gray scale voltages based on the gamma characteristic curve.

Display apparatus and driving device for displaying

Display driving arrangements including: generation circuit dividing a reference voltage by variable resistors for plural levels of voltages; a decoder circuit decoding gray scale voltage corresponding to the display data among the levels of voltages; and a register setting variable resisters resistance values to adjust amplitude and gradient of the gamma characteristic curve of the gray scale voltages with respect to the gray scale number, the generation circuit having a group of resistive voltage dividing circuits dividing the reference voltage, a variable resister amplitude adjusting the gamma characteristic curve in accordance with register setting values connected with a side of the reference voltage in series, being closer to the side of the reference voltage than the group of resistive voltage dividing circuits, a variable resister to adjust the gradient of the gamma characteristic curve per the register setting values connected within the group of resistive voltage dividing circuits in series.

A display driving circuit to supply a gray scale voltage corresponding to display data to a display panel, the display driving circuit including: a generation circuit to divide a reference voltage to generate a plurality of levels of the gray scale voltages; an interface circuit; a selection circuit to select the gray scale voltage corresponding to the display data from the plurality of levels of voltages; a first register to store a setting value that adjusts the amplitude of a gamma characteristic curve from outside via the interface circuit; and a second register to store a setting value that adjusts the gradient of the gamma characteristic curve from outside via the interface circuit; and a third register to store a setting value for micro adjusting the gamma characteristic curve from outside via the interface circuit; wherein the first, second and third registers are assigned different addresses.

A display driver used in common for a first screen and a second screen. The display driver includes a data line drive circuit which supplies gray scale voltages to the first and second screens in accordance with display data via data lines in common for the first and second screens, and a scan line drive circuit which supplies scan signals to the first and second screens via scan lines, with the scan lines in the first screen being different from the scan lines in the second screen. The scan line drive circuit scans the second screen in one of a one-line-at-a-time operation and a plural-line-at-a-time operation by using the scan signals every time the scan line drive circuit scans at least one frame of the first screen in a one-line-at-a-time operation by using the scan signals.

Device for driving a display apparatus

A driving circuit provided by the present invention is characterized in that the driving circuit selects a gray-scale voltage in accordance with high-order bits of display data from a group of gray-scale voltages with their voltage level varying step by step from fractional time period to fractional time period, which are set in advance, and outputs the selected gray-scale voltage during a time period between the start of a scanning period and a time at which a number assigned to a fractional time period matches quantitative information contained in low-order bits of the display data. In addition, the driving circuit provided by the present invention is also characterized in that the time ratio of the first fractional time period is set at a relatively high value while the time ratios of the second and subsequent fractional time periods are each set at a relatively low value.

Driving circuits for display device

A display driver adjustable for a gamma specification of a liquid display panel, including: a system interface receiving display data from an external; a memory storing the display data; a grayscale voltage generator generating a plurality of grayscale voltages; a gamma adjusting circuit adjusting the gamma specification; and an output circuit outputting the grayscale voltage in response to the display data from the memory to the liquid display panel, wherein the gamma adjusting circuit includes: a gradient adjustment register controlling variable resistors of a ladder resistor; an amplitude/reference adjustment register; and a micro adjustment register, wherein the gradient adjustment register, the amplitude/reference adjustment register and micro adjustment register, are independently set in accordance with red, green and blue, respectively.

A driving display device includes a gray scale voltage generating circuit for generating a plurality of levels of gray scale voltages from a reference voltage, an amplitude adjustment register capable of setting the amplitude of a characteristic curve of a plurality of levels of the gray scale voltages with respect to gray scale numbers, and a gradient adjustment register capable of setting the gradient of the characteristic curve. With this arrangement, the gradient and amplitude of the gray scale number-gray scale voltage characteristic are adjusted.

A display apparatus includes a data driver that is common to a main screen and a sub screen, and the data driver applies, to the main screen, a tone voltage corresponding to display data from a CPU, and during a vertical blanking time-period of the main screen, the data driver applies, to the sub screen, a tone voltage corresponding to black data or white data, and also includes a scan driver scans the main screen and scans the sub screen during the vertical blanking time-period of the main screen.

Display apparatus

There is provided a device for driving a display apparatus. A data line drive section is common to a main screen and a sub-screen, supplies to the main screen gray scale voltages corresponding to display data from CPU, and supplies to the sub-screen a gray scale voltage corresponding to black or white data during a vertical blanking period of the main screen. A scan line drive section scans the main screen, and also scans the sub-screen during the vertical blanking period of the main screen.

Growing community of inventors

Chigasaki, Japan

Hiroki Aizawa