Display apparatus having a full-color display

• US 6,392,620 B1
• Filed: 11/05/1999
• Issued: 05/21/2002
• Est. Priority Date: 11/06/1998
• Status: Expired due to Fees

• Current Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Original Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Inventors: Mizutani, Hidemasa, Onitsuka, Yoshihiro
• Primary Examiner(s): NGUYEN, CHANH DUY
• Application Number:
  US09/434,297
• Time in Patent Office: 928 Days
• Field of Search: 345/88, 345/89, 345/87, 345/92, 345/103, 345/72, 345/83, 345/96, 345/99, 345/91
• US Class Current: 345/88
• CPC Class Codes: G09G 2300/0809 Several active elements per pixel in active matrix panels
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2310/0235 Field-sequential colour display
• CPC Class Codes: G09G 2310/061 for resetting or blanking
• CPC Class Codes: G09G 2310/063 Waveforms for resetting the whole screen at once
• CPC Class Codes: G09G 2320/0257 Reduction of after-image effects
• 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 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 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence

Abstract

A display apparatus features an optical modulation device including a plurality of pixels and a pair of electrodes to which a voltage is applied, and an illumination device for illuminating the optical modulation device instantaneously and successively with a plurality of monochromatic lights of different colors in a frame period to provide a full-color image in combination with application of the voltage to the electrodes of the optical modulation device thereby effecting a full-color display over a succession of the prescribed period. A controller divides each frame period into two periods including a first period for displaying a full-color image at each pixel and a second period immediately after the first period and for placing the optical modulation device in a non-display state, thus effectively suppressing an after image phenomenon adversely affecting a full-color image display in a subsequent frame period.

Claims

1. A display apparatus, comprising:

an optical modulation device including a plurality of pixels and a pair of electrodes to which a voltage is applied,

an illumination device for illuminating said optical modulation device instantaneously and successively with a plurality of monochromatic lights of different colors in a prescribed period to provide a full-color image in combination with application of the voltage to the electrodes of said optical modulation device thereby effecting a full-color display over a succession of the prescribed period, and

control means for dividing each prescribed period into two periods including a first period for displaying a full-color image at each pixel and a second period immediately after the first period and for placing the optical modulation device in a non-display state, wherein

the second period is longer than a period from termination of illumination with a monochromatic light to initiation of illumination with a subsequent monochromatic light within the first period.

2. An apparatus according to claim 1, wherein the non-display state is provided by effecting a black image display in said optical modulation device.

3. An apparatus according to claim 1, wherein the non-display state is provided by terminating the illumination with the plurality of monochromatic lights.

4. An apparatus according to claim 1, wherein the plurality of monochromatic lights includes a green light with which the optical modulation device is illuminated last in each first period.

5. An apparatus according to claim 1, wherein the plurality of monochromatic lights comprises a red light, a green light and a blue light.

6. An apparatus according to claim 1, wherein the first period is substantially at least half of the prescribed period.

7. A liquid crystal apparatus, comprising:

a liquid crystal device including a liquid crystal, a plurality of pixel electrodes for applying a voltage to said liquid crystal arranged in a matrix form, a plurality of thin film transistors for simultaneous transfer connected to said pixel electrodes, a sample-and-hold circuit connected to said thin film transistors for simultaneous transfer, and a plurality of thin film transistors for successive charge storage connected to said sample-and-hold circuit,

means for generating picture image signals for defining gradation images for three primary colors to be visually recognized and displayed on said liquid crystal device as a full-color image, and

a light source for illuminating said liquid crystal device with a plurality of color, lights corresponding to the gradation images displayed on said liquid crystal device in a three primary color sequential display scheme, wherein

said liquid crystal exhibits a voltage-transmittance characteristic of showing a transmittance increasing monotonously in response to a voltage of one polarity and a transmittance which is non-zero but is substantially unchanged in response to a voltage of the other polarity.

8. An apparatus according to claim 7, wherein the full-color image is displayed in each frame by applying a voltage wave form to said liquid crystal, with each frame including a first period for displaying the full-color image and a second period for not displaying the full-color image, and said voltage waveform including a first voltage of a first polarity and a second voltage of a second polarity opposite to the first polarity for the first voltage.