Liquid crystal display with several capacitors for holding information at each pixel

• US 5,566,010 A
• Filed: 04/04/1994
• Issued: 10/15/1996
• Est. Priority Date: 04/10/1991
• Status: Expired due to Term

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Tsuchihira, Terutoshi, Ishii, Yutaka, Yamamoto, Yoshitaka
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US08/222,162
• Time in Patent Office: 925 Days
• Field of Search: 359/68, 359/100, 359/98, 359/53, 359/70, 359/93, 359/85, 359/57, 359/59, 359/55, 359/58, 340/784, 345/98, 345/100, 345/186, 345/196, 345/88, 345/90, 345/93, 345/101
• US Class Current: 349/42
• CPC Class Codes: G02F 1/13475 in which at least one liquid crystal cell or layer is doped with a pleochroic dye, e.g. GH-LC cell G02F1/13476 takes precedence
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2300/0852 being a dynamic memory with more than one capacitor
• CPC Class Codes: G09G 2310/0235 Field-sequential colour display
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336
• CPC Class Codes: G09G 3/3413 Details of control of colour illumination sources
• 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

Abstract

It is an object of the invention to present a liquid crystal display device capable of displaying high precisely and brightly. The incident light into the reflection type liquid crystal display element is selectively varied by using the light selecting means, that is, cyan filter, magenta filter, and yellow filter, and red light, green light, and blue light are entered in every unit time. By controlling the reflection/cutoff of color lights of these three primary color by the reflection type liquid crystal display element, multicolor display of eight colors or full-color display is realized.

Claims

1. A reflection type liquid crystal display device having a display mode, said device comprising:

an active matrix liquid crystal display element having a transparent substrate, a second substrate having light reflecting means for reflecting the incident light coming from a transparent substrate side, electrodes formed on confronting surfaces of said substrates, and an interposing liquid crystal composition between the transparent substrate and the second substrate,

pixels defined by overlapping regions of the electrodes, each pixel having a respective driving circuit corresponding to pixels individually and including a respective first signal holding capacitor connected to a picture element capacitor through a buffer circuit, a voltage supply line for driving a respective pixel being different from a voltage supply line to the respective first signal holding capacitor;

means for holding driving signal information to be displayed on the pixel in a next time frame While display is performed in a current time frame.

2. A liquid crystal display device of claim 1, wherein the color selecting means comprises multiple layers, each layer permitting a different wavelength of light to pass through, each layer being coextensive with said liquid crystal display element.

3. The liquid crystal display device or claim 2, wherein one or more of said transparent substrates have an anti-reflective film thereon.

4. A liquid crystal display device of claim 1, wherein the color selecting means comprises:

a cyan filter having a pair of transparent substrates, transparent electrodes extending nearly over the entire area of the confronting surface of said pair of transparent substrates, and an interposing liquid crystal composition containing dichroic pigment of cyan between the pair of transparent substrates,

a magenta filter having a pair of transparent substrates, transparent electrodes extending nearly over the entire area of the confronting surface of said pair of transparent substrates, and an interposing liquid crystal composition containing dichroic pigment of magenta between the pair of transparent substrates,

a yellow filter having a pair of transparent substrates, transparent electrodes extending nearly over the entire area of the confronting surface of said pair of transparent substrates, and an interposing liquid crystal composition containing dichroic pigment of yellow between the pair of transparent substrates, and

filter driving means for applying a voltage selectively to the transparent electrodes of the cyan filter, the magenta filter and the yellow filter.

5. A liquid crystal display device of claim 4, wherein the filter driving means (i) sequentially drives the cyan filter, magenta filter and yellow filter in every predetermined unit time, thereby providing a red display period in which the incident light to the liquid crystal display element is red, a green display period in which it is green, and a blue display period in which it is blue, and (ii) sets the unit display period as the sum of the red display period, green display period and blue display period.

6. A liquid crystal display device of claim 5, further comprising the respective driving circuits controlling a quantity of reflected light in each pixel in each display period comprising a unit display period.

7. A liquid crystal display device of claim 6, wherein the quantity of reflected light in each pixel is either at 0 or at a predetermined value.

8. A liquid crystal display device of claim 6 wherein the quantity of reflected light in each pixel is changed continuously or stepwise between 0 and a predetermined value.

9. The liquid crystal display device of claim 4, wherein one or more of said transparent substrates have an anti-reflective film thereon.

10. A liquid crystal display device of claim 1, 2, 4, 5, 6, 7 or 8, wherein the liquid crystal display element is an active matrix type liquid crystal display element having one common electrode over substantially the entire surface of the transparent substrate, and having plural display electrodes for forming pixels on the confronting side of the second substrate.

11. A liquid crystal display device of claim 10, wherein the driving circuits are controlled by display control means for producing a scanning signal for specifying the plural display electrodes individually, and a driving signal for applying a voltage to each display electrode.

12. A liquid crystal display device of claim 11, wherein the respective driving circuits include:

a signal scanning part controlled by the scanning signal for producing the driving signal in an On state,

said buffer circuit applying a voltage to a display electrode according to the driving signal from the signal scanning part, and

said first signal holding capacitor disposed between the signal scanning part and buffer circuit for holding the potential of the driving signal from the signal scanning part.

13. A liquid crystal display device of claim 11, wherein the respective driving circuits include:

a signal scanning part controlled by the scanning signal for producing the driving signal in an On state,

said buffer circuit applying a voltage to the display electrode according to the driving signal from the signal scanning part,

said means for holding driving signal information being a second signal holding capacitor disposed between the signal scanning part and buffer circuit for holding the potential of the driving signal from the signal scanning part, and

connection changeover means for connecting the second signal holding capacitor to the buffer circuit when connecting the first signal holding capacitor to the signal scanning part, and connecting the first signal holding capacitor to the buffer circuit when connecting the second signal holding capacitor to the signal scanning port.

14. The liquid crystal display device of claim 10, wherein the active matrix liquid crystal display element comprises a substrate containing amorphous silicon, polycrystalline silicon or monocrystalline silicon.

15. A liquid crystal display device of claim 1, wherein the display mode is a phase transition mode or a high molecular dispersion type liquid crystal mode.

16. The liquid crystal display device of claim 1, further comprising an anti-reflective film on said transparent substrate.

17. The liquid crystal display device of claim 1, having a cell thickness d and an intrinsic spiral pitch p wherein d/p≧

2 and d≦

10 μ

m.

18. The liquid crystal display device of claim 1, wherein the liquid crystal material comprises a structure made of phenylcyclohexane liquid crystal or fluorinated liquid crystal.

19. The liquid crystal display device of claim 1, wherein the active matrix liquid crystal display element comprises an active matrix substrate comprising a polysilicon material or a monocrystalline silicon material as an active element material.

20. The liquid crystal display device of claim 19, wherein the liquid crystal composition comprises a liquid crystal material for a two frequency driving mode, a liquid crystal material for a high molecular dispersion type liquid crystal display mode, or a liquid crystal material comprising a dichroic pigment in a display element having a cell thickness d and an intrinsic spiral pitch p wherein d/p≧

2 and d≦

10 μ

m for a phase transition display mode.

21. The device of claim 1 further including color selecting means disposed at the transparent substrate side of the liquid crystal display element for varying the wavelength of the incident light to the liquid crystal display element in every predetermined unit time.

22. The device of claim 1 wherein the liquid crystal composition comprises a chiral nematic liquid crystal material, a liquid crystal material for a two frequency driving mode, a liquid crystal material for a high molecular dispersion type liquid crystal display mode, a liquid crystal material for a ferroelectric liquid crystal display mode, or a liquid crystal material for a phase transition display mode.