Field-sequential color display unit and display method

• US 20020122019A1
• Filed: 12/18/2001
• Published: 09/05/2002
• Est. Priority Date: 12/21/2000
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Okumura, Haruhiko, Taira, Kazuki, Baba, Masahiro
• Granted Patent: US 6,911,963 B2
• Time in Patent Office: Days
• US Class Current: 345/88
• CPC Class Codes: G02B 2027/0112 comprising device for genereting colour display
• CPC Class Codes: G02B 2027/014 comprising information/image processing systems
• CPC Class Codes: G02B 26/008 in the form of devices for effecting sequential colour changes, e.g. colour wheels
• CPC Class Codes: G02B 27/017 Head mounted
• CPC Class Codes: G09G 2310/0235 Field-sequential colour display
• CPC Class Codes: G09G 2320/0242 Compensation of deficiencies in the appearance of colours
• CPC Class Codes: G09G 2320/0261 in the context of movement of objects on the screen or movement of the observer relative to the screen
• CPC Class Codes: G09G 2320/103 Detection of image changes, e.g. determination of an index representative of the image change
• CPC Class Codes: G09G 2340/06 Colour space transformation
• CPC Class Codes: G09G 3/3413 Details of control of colour illumination sources
• CPC Class Codes: G09G 3/36 using liquid crystals
• CPC Class Codes: G09G 3/3607 for displaying colours or for displaying grey scales with a specific pixel layout, e.g. using sub-pixels display of colours in flat matrix panels other than liquid crystal displays G09G3/2003; grey scales specific for television H04N3/127
• CPC Class Codes: G09G 5/02 characterised by the way in which colour is displayed details of colour display specific for CRTs G09G1/28; specific for flat matrix panels other than liquid crystal displays G09G3/2003; specific for liquid crystal displays G09G3/3607
• CPC Class Codes: H04N 9/22 using the same beam for more than one primary colour information H04N9/27 takes precedence
• CPC Class Codes: H04N 9/30 using solid-state colour display devices
• CPC Class Codes: H04N 9/3111 for displaying the colours sequentially, e.g. by using sequentially activated light sources sequential projection in colour photography G03B33/08
• CPC Class Codes: H04N 9/3114 by using a sequential colour filter producing one colour at a time
• CPC Class Codes: H04N 9/3179 Video signal processing therefor

Abstract

There is provided a field-sequential color displaying method capable of reducing color breakup with respect to an optional image without greatly increasing a sub-field frequency. The field-sequential color display method includes; time-sequentially displaying of luminous information of an input image information with every display color and changing the display color in synchronism with the displaying of the luminous information in order to display the input image information, wherein one frame period in which one color image is displayed includes at least four sub-field periods in which information of each color is displayed, and a picture signal displayed in at least one sub-field period is a non-three-primary color picture signal which is generated from at least two primary color signals of input picture signals including three-primary color signals.

Claims

1. A field-sequential color display method comprising:

time-sequentially displaying of luminous information of an input image information with every display color; and

changing the display color in synchronism with the displaying of the luminous information in order to display the input image information,

wherein one frame period in which one color image is displayed comprises at least four sub-field periods in which information of each color is displayed, and a picture signal displayed in at least one sub-field period is a non-three-primary color picture signal which is generated from at least two primary color signals of input picture signals including three-primary color signals.

2. A field-sequential color display method as set forth in claim 1, wherein the non-three-primary color picture signal displayed in the sub-field period is determined on the basis of the input image information.

3. A field-sequential color display method as set forth in claim 2, wherein the display colors of the primary color signals include red, green and blue, and the display color of the non-three-primary color picture signal is any one of white, cyan, magenta and yellow which are generated from the at least two primary color picture signals.

4. A field-sequential color display method as set forth in claim 2, wherein the non-three-primary color picture signal displayed in the sub-field period is determined on the basis of a part of image information of the input image information in one frame period.

5. A field-sequential color display method as set forth in claim 1, wherein the non-three-primary color picture signal displayed in the sub-field period is determined on the basis of the input image information every a predetermined frame interval including a plurality of frame periods.

6. A field-sequential color display method as set forth in claim 1, wherein the non-three-primary color picture signal displayed in the sub-field period is determined with every scene change of the input image information.

7. A field-sequential color display method as set forth in claim 1, wherein the picture signal displayed in each of the sub-field periods is one of modified picture signals which are obtained by separating the input picture signal into the n non-three-primary color picture signals and three modified three-primary color picture signals when n is an integer of 1 or more.

8. A field-sequential color display method as set forth in claim 7, wherein the picture signal displayed in the sub-field period comprises the separated and modified three-primary color picture signals, and the n non-three-primary color picture signals which are generated from the at least two primary color picture signals and which have a higher mean signal intensity than that of at least one of the modified three-primary color picture signals.

9. A field-sequential color display method as set forth in claim 7, wherein the separation of the picture signals is carried out by detecting the minimum value of the three-primary color picture signals, causing the minimum value to be set as the signal value of a first non-three-primary color picture signal of the non-three-primary color picture signals, and causing a smaller signal value of two modified picture signals, which are obtained by subtracting the minimum value from the three-primary color picture signal values and which are not zero, to be set as a second non-three-primary color picture signal of the non-three-primary color picture signals.

10. A field-sequential color display method as set forth in claim 7, which includes converting process of the input picture signal into a chromaticity coordinates when the input picture signal is separated into the n non-three-primary colors picture signals and the modified three-primary color picture signals.

11. A field-sequential color display unit comprising:

a non-three-primary color picture signal generator generating a non-three-primary color picture signal by selecting at least two primary color picture signals of three-primary color signals on the basis of an input picture signal including the three-primary color signals;

a monochrome image display sequentially displaying a input picture signal as a monochrome image;

a color display capable of changing a display color every sub-field period at least four of which constitutes one frame period, in which one image is displayed, in synchronism with the monochrome image displaying; and

a display color controller controlling the color display so as to display the non-three-primary color picture signal in at least one of the sub-field periods.

12. A field-sequential color display unit as set forth in claim 11, wherein the display colors of the primary color signals include red, green and blue, and the display color of the non-three-primary color picture signal is any one of white, cyan, magenta and yellow which are generated from the at least two primary color picture signals.

13. A field-sequential color display unit as set forth in claim 11, wherein the non-three-primary color picture signal generator includes a signal separating circuit separating the three-primary color signals from the input picture signal, and generates the non-three-primary color picture signal from the three-primary color signals separated by the signal separating circuit.

14. A field-sequential color display unit as set forth in claim 11, wherein the monochrome image display is a self-emissive type-monochrome image display unit, and the color display is a color filter which is provided in front of the monochrome image display unit and which is capable of time-sequentially changing transmitted color.

15. A field-sequential color display unit as set forth in claim 14, wherein the color filter is a liquid crystal color shutter comprising liquid crystal cells, and a plurality of polarizers.

16. A field-sequential color display unit as set forth in claim 11, wherein the field-sequential color display unit is a projection type-display unit having an optical lens for enlarging or reducing a field-sequentially displayed color image to project the image on a screen.

17. A field-sequential color display unit as set forth in claim 11, wherein the color display is a color wheel.

18. A field-sequential color display unit as set forth in claim 11, wherein the field-sequentially color display unit is a head mounted display observing a field-sequentially displayed color image via an enlarging optical system.

19. A field-sequential color display unit as set forth in claim 11, wherein the monochrome image display is a transmissive type-liquid crystal light valve, and the color display is a backlight provided on the back side of the transmissive type-liquid crystal light valve, the backlight having g a plurality of light sources capable of time-sequentially selecting or combining three-primary colors to emit light.