Display device conversion device, display device correction circuit, display device driving device, display device, display device examination device, and display method

• US 7,382,382 B2
• Filed: 12/22/2003
• Issued: 06/03/2008
• Est. Priority Date: 12/27/2002
• Status: Expired due to Fees

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Ueno, Masafumi, Furukawa, Hiroyuki, Yoshida, Yasuhiro
• Primary Examiner(s): Tran; Henry N
• Application Number:
  US10/740,795
• Publication Number:
  US 20040150602A1
• Time in Patent Office: 1,625 Days
• Field of Search: 345 87- 90, 345204-207, 345/596, 345/600, 345/690, 345/214, 348/254, 348/671, 348/674, 382/274, 382/300, 382/299, 358/448, 358/519, 358/523
• US Class Current: 345/690
• CPC Class Codes: G09G 2320/0276 for the purpose of adaptation to the characteristics of a display device, i.e. gamma correction
• CPC Class Codes: G09G 2320/0285 using tables for spatial correction of display data
• CPC Class Codes: G09G 3/2051 with use of a spatial dither pattern
• CPC Class Codes: G09G 3/3688 suitable for active matrices only
• CPC Class Codes: H04N 9/315 Modulator illumination systems general applications of lighting devices F21V; general optical systems G02B; lamp houses for projectors not peculiar to the presence of an electronic spatial light modulator G03B21/20
• CPC Class Codes: H04N 9/69 for modifying the colour signals by gamma correction controlling camera response for colour signals H04N23/83

Abstract

The liquid crystal display device inputs a signal, corrected by a correction circuit provided with a sigmoid inverse function generator, to a source driver. A sigmoid function which is an S-shaped function is used to approximate an input/output characteristic (applied voltage-transmittance curve) of a liquid crystal panel. The sigmoid inverse function generator converts an input signal by using an inverse function of the sigmoid function obtained by performing the approximation. A γ conversion circuit provided on the correction circuit and the sigmoid inverse function generator realize the desired γ characteristic regardless of a characteristic of the liquid crystal panel. Further, since the inverse function of the sigmoid function which is an S-shaped function is used, it is possible to provide a display device which corrects the input/output characteristic of the display panel by performing the approximation in accordance with not plural functions but a single function (without dividing the characteristic into sections).

Claims

1. A display device conversion device, converting a video signal inputted to a display device so as to output the video signal to a display panel,

wherein said conversion device converts the video signal by using an inverse function of a sigmoid function obtained by approximating an input/output characteristic indicative of a relationship between an input to the display panel and a display output of the display panel,

wherein the sigmoid function is a monotonically increasing function having a saturation characteristic, and

wherein the sigmoid function contains three or more parameters.

2. A display device correction circuit, which corrects a video signal inputted to a display device so as to output the video signal to a display panel, comprising:

a γ

conversion circuit for converting the video signal so that the video signal has a desired γ

characteristic; and

a display device conversion device for converting the video signal by using an inverse function of a sigmoid function obtained by approximating an input/output characteristic indicative of a relationship between an input to the display panel and a display output of the display panel, and

a state amount calculation setting circuit for calculating a state amount of an image displayed by the video signal, in accordance with the video signal, so as to set the γ

characteristic of the γ

conversion circuit in accordance with the state amount.

3. The display device correction circuit as set forth in claim 2, wherein the state amount indicates dispersion and an average value of luminance in the image displayed in the display panel.

4. The display device correction circuit as set forth in claim 3, wherein

the state amount calculation setting circuit includes:

a luminance calculating section for calculating each pixel luminance of an image displayed in the display panel;

an average calculating section for calculating average luminance of a single image by using said each pixel luminance;

a dispersion calculating section for calculating dispersion of luminance of the single image by using said each pixel luminance; and

data generating section for setting the y characteristic in accordance with the average luminance and the dispersion of the luminance.