Fujitsu General Limited

Hayato Denda

Masayuki Kobayashi

Masamichi Nakajima

Junichi Onodera

Asao Kosakai

Seiji Matsunaga

Toru Aida

In a moving image correcting circuit for a display unit wherein a motion vector detecting portion detects inter-frame motion vectors and a moving image correcting position corrects the display positions of subfields for pixels in blocks, based on the detection values, the picture quality is protected from being degraded by preventing the output of an erroneous motion vector due to noise in, or fluctuation of, the input image signal or else preventing the erroneous motion vector, even if output from the motion vector detecting portion, from entering the moving image correcting portion.

Moving image correcting circuit for display device

A motion vector difference detection stage detects a difference D in motion vector between a current frame and a succeeding frame and a difference D in motion vector between a preceding frame and current frame. A latched circuit outputs the motion vector S of the inputted current frame as a motion vector S in the case where both of the absolute values of the differences D and D does not exceed a preset value L , and outputs the motion vector S of the frame preceding the corresponding frame as a motion vector S in the case where at least one of the absolute values of the differences D and D exceeds the preset value L . The latched circuit outputs a motion vector of 0 as a motion vector S in the case where both of the absolute values of the differences D and D exceed the preset value L and also the absolute value of the sum of the differences D and D exceeds the preset value L . When a change in motion vector is small, the motion vector of the corresponding frame carries out dynamic image correction. When a change in motion vector is large, the small motion vector of the preceding frame or the motion vector of 0 carries out dynamic image correction.

Motion vector processing circuit

In a subfield drive method, two subframes of the least brightness are arranged adjacently to each other to select and light up the display device in terms of the change in image brightness in the time axial direction. When, for example, the level of original signal changes from 7 to 8 or from 8 to 7, SF , SF , SF and SF are selected as subframes for level 8, and SF , F and SF are selected as subframes for level 7. This prohibiting any continuous lighting or non-lighting at the levels 7 and 8, there is no substantial change in brightness nor degradation of picture quality at that time. Any distortion of moving image (pseudo contour) is removed by the correction circuit having the frame memory that delays by one frame, the correction constant set circuit that outputs correction data, and the adder that adds the correction data to the original image signal.

Drive method and drive circuit of display device

A display device which displays a multilevel gradation image by dividing a frame into a plurality of subfields in respect of time and by allowing the subfields corresponding to the luminance levels of the input image signals to emit light, comprising a motion vector detection unit which detects the motion vector which expresses the motion of a block from one frame to the next, a high speed dynamic image correction unit and a law speed dynamic image correction unit which correct the input image signal by dynamic image correcting means which are suitable for the respective cases when the value of the detected motion vector is larger than a preset value S and when it is smaller than the preset value S and output the corrected input image signal, and a switching unit which elects either the output signal of the high speed dynamic image correction unit or the output signal of the law speed dynamic image correction unit to output the selected signal to the display in accordance with whether or not the value of the detected motion vector is larger than the preset value S. As a result, both the high speed dynamic image part and the low speed dynamic image part of the image can be optimally corrected.

Dynamic image correction method and dynamic image correction circuit for display device

In an error diffusion processing unit to get a false half tone diffusing in the surroundings the luminance error between the original picture element signal quantizedly input and the preceding data, one dot of said signal is converted into plural picture elements. The respective picture elements (pixels) thus converted are compared with the prior data to detect the luminance error, which will then be weighted by multiplying it with certain coefficient to give, for instance, the reproduced error in one line past, that in one dot past and further the reproduced error a in one-line and one-dot past, which will respectively be added to the original pixels. Producing a false tone by error variance in unit of pixel enables to display the half tone without expanding the half tone display area beyond required dot number.

Drive for a display device

In a display device in which each group of plural drive elements takes charge of the drive of plural picture elements (pixels) and the display luminance changes as the number of sustaining pulses changes that are supplied to a plasma display panel, a constant emission luminance characteristic is maintained by increasing the number of sustaining pulses for a larger load when the display load factor is large, and decreasing the number of sustaining pulses for a smaller load when the display load factor is small. When displaying a multi-tone image by a subfield drive method, a display area detect circuit allows the display of an image with constant luminance characteristic despite the variation of the display load factor, and prevents the deterioration of tone characteristic due to the subfield drive method, and further, a half tone display circuit allows the decrease of the bit number thereby simplifying the configuration of the display area detect circuit.

Drive circuit for display device

Coupled to an error variance circuit 11 is an emission luminance characteristic acquisition circuit 20 that counts up, at a display number counter 21, the display number in the single or plural frames of the respective bits of image data by the counters, M in number, corresponding to said bits, then solves for display area percentage (Sk) dividing, at a display area percentage operation part 22, the display dot number as counted at a display number counter 21, by total dot number, and acquires the luminance deviation characteristic for each bit by means of an emission luminance deviation characteristic measuring part 24. The luminance deviation thus obtained is renewed for each frame and transferred to the error variance circuit 11, and processed for error variance on the basis of the emission luminance characteristic to be output at PDP. At low level, on the other hand, the luminance deviation is rendered either fixed type luminance deviation or emission luminance level more or less higher than the actual one to reduce the diffusion noise particularly at the low level image portion thereby obtaining a more natural image.

Error variance processing equipment for display device

An error variance circuit, wherein a reproduced error, as detected at an error detection circuit, is added to the image signal of the input signal picture element of n bits, and wherein a variance output signal is converted into a signal of m (.ltoreq.n-l) bits and outputted to a display panel, includes a clear circuit that clears error at each frame and forcibly reduces the prior error to zero thus preventing excessive noise from preceding frames and non-image duration causing flickering of picture.

Growing community of inventors

Kanagawa-ken, Japan

Hayato Denda