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

• US 20040150602A1
• Filed: 12/22/2003
• Published: 08/05/2004
• Est. Priority Date: 12/27/2002
• Status: Active Grant

• 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
• Granted Patent: US 7,382,382 B2
• Time in Patent Office: Days
• US Class Current: 345/98
• 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 an inputted video signal, by using an inverse function of a sigmoid function obtained by approximating an input/output characteristic of a display panel, so as to output the video signal.

2. The display device conversion device as set forth in claim 1, wherein the display panel is a liquid crystal panel.

3. The display device conversion device as set forth in claim 1, being constituted of a DSP (Digital Signal Processor).

4. The display device conversion device as set forth in claim 1, comprising an input interface for inputting a parameter contained in the sigmoid function.

5. A display device correction circuit, comprising:

a display device conversion device for converting a video signal inputted to the display device conversion device, by using an inverse function of a sigmoid function obtained by approximating an input/output characteristic of a display panel, so as to output the video signal; and

a γ

conversion circuit for converting a video signal inputted to the γ

conversion circuit so that an image displayed in the display panel has a desired γ

characteristic, so as to output the video signal.

6. The display device correction circuit as set forth in claim 5, wherein the display device conversion device and the γ

conversion circuit are connected to each other in this order so as to be disposed in a cascade manner.

7. The display device correction circuit as set forth in claim 5, wherein the desired γ

characteristic is γ

=1.8 to 2.4.

8. The display device correction circuit as set forth in claim 5, wherein the display device conversion device and the γ

conversion circuit are constituted of a single conversion table.

9. A display device, comprising:

a display device conversion device for converting an inputted video signal, by using an inverse function of a sigmoid function obtained by approximating an input/output characteristic of a display panel, so as to output the video signal; and

the display panel for displaying an image in accordance with the video signal converted by the display device conversion device.

10. A display device, comprising:

a display device correction circuit which includes (i) a display device conversion device for converting a video signal inputted to the display device conversion device, by using an inverse function of a sigmoid function obtained by approximating an input/output characteristic of a display panel, so as to output the video signal and (ii) a γ

conversion circuit for converting a video signal inputted to the γ

conversion circuit so that an image displayed in the display panel has a desired γ

characteristic, so as to output the video signal; and

the display panel for displaying an image in accordance with the video signal outputted by the display device conversion device.

11. A display device driving device, generating a driving voltage for driving a display panel in accordance with a video signal that has been converted by 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 of the display panel, so as to output the video signal.

12. A display device examination device, comprising:

a luminance measuring device for measuring luminance of a display panel which displays an image in accordance with a video signal converted by 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 of a display panel, so as to output the video signal; and

a parameter calculating section for calculating a parameter contained in the sigmoid function of the display device conversion device, in accordance with a measurement result given by the luminance measuring device, so as to output the parameter to the display device conversion device.

13. 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 single 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.

14. The display device conversion device as set forth in claim 13, wherein the single function is a sigmoid function which is a monotonously increasing function having a saturation characteristic.

15. The display device conversion device as set forth in claim 14, comprising a storage element for storing the inverse function of the sigmoid function as a conversion table.

16. The display device conversion device as set forth in claim 15, wherein the storage element is rewritable.

17. The display device conversion device as set forth in claim 14, wherein the sigmoid function contains three or more parameters.

18. 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 single 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.

19. The display device correction circuit as set forth in claim 18, comprising 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.

20. The display device correction circuit as set forth in claim 19, wherein the state amount indicates dispersion and an average value of luminance in the image displayed in the display panel.

21. The display device correction circuit as set forth in claim 20, 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

a data generating section for setting the γ

characteristic in accordance with the average luminance and the dispersion of the luminance.

22. 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 gradation resolution increasing section for increasing gradation resolution of the video signal; and

a display device conversion device for converting an output from the gradation resolution increasing section by using an inverse function of a single 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.

23. The display device correction circuit as set forth in claim 22, further comprising a gradation interpolation circuit for (i) decreasing gradation resolution of an output from the display device conversion device and (ii) interpolating gradation by performing time-series calculation or area coverage modulation.

24. A display device driving device, generating a driving signal from a video signal inputted to a display device so as to output the driving signal to a display panel, wherein

an output signal to the display panel is generated in accordance with an output from a display device conversion device for converting the video signal by using an inverse function of a single 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.

25. A display device, causing a display panel to display an image based on an inputted video signal, wherein

the display panel displays the image based on the video signal which has passed through a display device conversion device for converting the video signal by using an inverse function of a single 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.

26. A display device examination device, which examines a display panel for displaying an image based on an inputted video signal, comprising:

a parameter calculating section for setting a parameter contained in a function used by a display device conversion device which converts the video signal by using an inverse function of a single 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, so as to give the parameter to the display device conversion device; and

a luminance measuring device for measuring luminance of the display panel which displays an image based on the video signal outputted from the display device conversion device, in accordance with the parameter set by the parameter calculating section, wherein

the parameter calculating section calculates the parameter in accordance with a measurement result given by the luminance measuring device.

27. A display method for displaying an image based on an inputted video signal, comprising the step of converting the video signal in accordance with a monotonously increasing function, being sequential and differentiable from a minimum level to a maximum level of the video signal, which has a saturation characteristic.