Abstract: The current drive device of the present invention includes: a current source transistor for allowing a preset drive current to flow to a drain; a cascode transistor cascode-connected to the current source transistor; a switch circuit for switching ON/OFF flow of the drive current through the drain of the cascode transistor and a circuit to be driven; and a bypass circuit for allowing the drive current to flow therethrough to bypass the switch circuit and the circuit to be driven when the switch circuit is OFF.

Abstract: To improve accuracy of determining the average brightness level and maximum and minimum levels of the brightness signals for the entire screen. There are included a differential operation circuit that detects and differentiates rise or breaking edges in horizontal and vertical synchronous signals of an input image signal, thereby outputting horizontal and vertical differential signals synchronized with the horizontal and vertical synchronous signals, respectively; a sample window circuit that detects the beginning and ending positions of horizontal and vertical intervals to produce sample window signals established in any desired vertical and horizontal positions on the screen in accordance with the horizontal and vertical differential signals; and a brightness signal output circuit that outputs sampled brightness signals when the sample window circuit is operative.

Abstract: A driving device for driving an image display system, which sequentially receives input image data corresponding to gradation of each pixel of a display image and outputs a driving voltage signal includes: an operation section for obtaining output image data of which a bit number is smaller than a bit number of the input image data based on input image data of a target pixel to be processed and input image data of a pixel in vicinity of the target pixel; a reference voltage generation section for generating a plurality of reference voltages of different levels; and a reference voltage selection section for selecting one of the plurality of reference voltages. The operation section is configured to obtain output image data of the target pixel so that a difference between the input image data and output image data of the target pixel and a difference between the input image data and output image data of the pixel in vicinity of the target pixel cancel out each other.

Abstract: A noise shaping processing part performs noise shaping processing on pixel data. An adding circuit performs accumulative adding processing on the noise-shaped pixel data. A first bit-shift part performs bit-shift processing on the accumulatively-added and noise-shaped pixel data. A second bit-shift part performs bit-shift processing on unprocessed pixel data. An inter-pixel subtracting circuit calculates a gradation level difference between neighboring current pixel and previous pixel in a horizontal direction in the unprocessed pixel data. A boundary judging circuit judges presence of a boundary between a low-gradation area and a high-gradation area in the horizontal direction of the unprocessed pixel data, based on a comparison between the gradation level difference and a prescribed threshold value.

Abstract: [PROBLEMS]To improve accuracy of determining the average brightness level and maximum and minimum levels of the brightness signals for the entire screen. [MEANS FOR SOLVING THE PROBLEMS]There are included a differential operation circuit that detects and differentiates rise or breaking edges in horizontal and vertical synchronous signals of an input image signal, thereby outputting horizontal and vertical differential signals synchronized with the horizontal and vertical synchronous signals, respectively; a sample window circuit that detects the beginning and ending positions of horizontal and vertical intervals to produce sample window signals established in any desired vertical and horizontal positions on the screen in accordance with the horizontal and vertical differential signals; and a brightness signal output circuit that outputs sampled brightness signals when the sample window circuit is operative.

Abstract: The current drive device of the present invention includes: a current source transistor for allowing a preset drive current to flow to a drain; a cascode transistor cascode-connected to the current source transistor; a switch circuit for switching ON/OFF flow of the drive current through the drain of the cascode transistor and a circuit to be driven; and a bypass circuit for allowing the drive current to flow therethrough to bypass the switch circuit and the circuit to be driven when the switch circuit is OFF.

Abstract: In a semiconductor device of the present invention, a clock is not changed instantaneously but it is changed over maximum N+1/M clocks (N: integer not less than 2) by shifting delay cells in a step by step manner to make the phase state of a previous reference signal and the phase state of a present reference signal coincide with each other, whereby the clock is synchronized with the reference signal with accuracy, and the duty of the output clock is kept constant. With this semiconductor device, it is possible to prevent the duty of the clock from being discontinuous when a signal whose reference signal does not coincide with the clock is inputted and reset is made to a rising edge of this reference signal.

Abstract: In a semiconductor device of the present invention, a clock is not changed instantaneously but it is changed over maximum N+1/M clocks (N: integer not less than 2) by shifting delay cells stepwisely to make the phase state of a previous reference signal and the phase state of a present reference signal coincide with each other, whereby the clock is synchronized with the reference signal with accuracy, and the duty of the output clock is kept constant. According to the semiconductor device of the present invention, it is possible to prevent the duty of the clock from being discontinuous when a signal whose reference signal does not coincide with the clock is inputted and reset is made to a rising edge of this reference signal.

Abstract: An object of the present invention is to provide a signal processor which improves the offset accuracy of a video signal without increasing the number of bits of a circuit. An N-bit adder (103) adds a video signal (S101) and an upper-N-bit signal of a brightness control signal (S102) as an offset value. A 1-bit pulse generator (107) generates a 1-bit pulse signal (S107) in which “1” and “0” have equal chances of appearing at random. A selector (106) selects the 1-bit pulse signal (S107) when the LSB of the brightness control signal (S102) is “1”, while selects a ground level “0” when the LSB is “0”, and supplies the selected signal to a carry input of the N-bit adder (103).

Abstract: An appropriate correction quantity is obtained for a video luminance signal on an individual video basis with a characteristic value, like the maximum or average value, of the luminance signal taken into account, thereby performing gray scale correction more effectively.

Abstract: The present invention provides a color difference signal correction apparatus for correcting color difference of parts having no color, particularly white characters, which can make the correction with high accuracy also for images including lightly colored parts.

Abstract: An object of the present invention is to provide a signal processor which improves the offset accuracy of a video signal without increasing the number of bits of a circuit.

Abstract: A large number of analog signals (Aa, Ba . . . Na) are time-division-multiplexed by an analog switch (12) into a single analog signal (c). The multiplexed analog signal (c) is converted by an A/D conversion circuit (8) into a digital signal (d). The digital signal (d) is separated by a signal separation circuit (14) into a large number of digital signals (e) respectively corresponding to the analog signals (Aa, Ba . . . Na). Each digital signal (e) is compared by a comparison circuit (9) with a digital reference value (f) having a predetermined value. A current source control circuit (10) generates a digital control signal (g) according to the amount of shift in the digital signal (e) with respect to the digital reference value (f), and the current source (11) is controlled by the control signal (g). Therefore, the clamp level of an analog signal is adjusted to a predetermined level with a high precision, thereby effectively suppressing the level shift thereof.

Abstract: An appropriate correction quantity is obtained for a video luminance signal on an individual video basis with a characteristic value, like the maximum or average value, of the luminance signal taken into account, thereby performing gray scale correction more effectively.