Projection type display device

• US 20040136204A1
• Filed: 10/20/2003
• Published: 07/15/2004
• Est. Priority Date: 10/21/2002
• Status: Active Grant

• Current Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Original Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Inventors: Asao, Yasufumi
• Granted Patent: US 6,939,013 B2
• Time in Patent Office: Days
• US Class Current: 362/561
• CPC Class Codes: G09G 2310/024 Scrolling of light from the illumination source over the display in combination with the scanning of the display screen
• CPC Class Codes: G09G 2310/08 Details of timing specific for flat panels, other than clock recovery
• CPC Class Codes: G09G 2320/02 Improving the quality of display appearance
• 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 2320/0271 Adjustment of the gradation levels within the range of the gradation scale, e.g. by redistribution or clipping
• CPC Class Codes: G09G 2320/064 by time modulation of the brightness of the illumination source
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 3/002 to project the image of a two-dimensional display, such as an array of light emitting or modulating elements or a CRT
• CPC Class Codes: G09G 3/025 with scanning or deflecting the beams in two directions or dimensions
• CPC Class Codes: G09G 3/342 using several illumination sources separately controlled corresponding to different display panel areas, e.g. along one dimension such as lines
• CPC Class Codes: G09G 3/3426 the different display panel areas being distributed in two dimensions, e.g. matrix
• CPC Class Codes: H04N 5/7408 Direct viewing projectors, e.g. an image displayed on a video CRT or LCD display being projected on a screen

Abstract

A projection type display device includes a light source, a picture information display element, and a light deflection device with a function to deflect light from the light source and irradiate the deflected light on a region of the picture information display element. The light deflection device scans the region on the picture information display element to be irradiated with light over the entire picture information display element within each frame period to thereby project a picture. A picture is displayed by changing the region on the picture information display element irradiated by light within a period of each one frame. The projection type display device provides sharp moving pictures and bright images. Furthermore, the projection type display device provides a wide dynamic range and faithful tone reproducibility for pictures that are mainly dark images. Moreover, the projection type display device can use a Half-V type FLC element for creating bright and sharp moving pictures.

Claims

1. A projection type display device comprising:

a light source;

a picture information display element; and

a light deflection device with a function to deflect light from the light source and irradiate the deflected light on one region of the picture information display element,

wherein the light deflection device scans the region on the picture information display element to be irradiated with light over an entire region of the picture information display element within each frame period to thereby project a picture.

2. A projection type display device according to claim 1, further comprising a light condensing device that condenses light from the light source and irradiate the condensed light on the light deflection device.

3. A projection type display device according to claim 1, wherein the picture information display element comprises a plurality of scanning lines, and the scanning lines are driven at different timings to change the region to be irradiated by the light.

4. A projection type display device according to claim 1, wherein a part of the plurality of scanning lines is scanned at a scanning speed lower than a scanning speed at another part of the plurality of scanning lines.

5. A projection type display device according to claim 1, wherein the picture information display element is composed of an effective scanning area and an area outside the effective scanning area, and the area outside the effective scanning area is irradiated with the light to create a period during which the light is not irradiated on the picture information display element.

6. A projection type display device according to claim 1, wherein the picture information display element comprises a plurality of scanning lines extending in a first direction that are scanned in a second direction transverse to the first direction.

7. A projection type display device according to claim 6, wherein the light from the light source irradiated on the picture information display element spans in an entire length of the picture information display element in the first direction, and on a part of the picture information display element in the second direction.

8. A projection type display device according to claim 7, wherein the picture information display element is entirely irradiated with the light by scanning the picture information display element in the second direction regions in a specified timing within each frame period.

9. A projection type display device according to claim 1, wherein the picture information display element has vertical and horizontal sides;

and the light from the light source irradiated on the picture information display element spans in an entire length of the picture information display element in a first direction parallel with one of the vertical and horizontal sides, and in a part of the picture information display element in a second direction perpendicular to the first direction.

10. A projection type display device according to claim 9, wherein the region on the picture information display element to be irradiated with the light is scanned in the second direction to irradiate an entire area of the picture information display element with the light.

11. A projection type display device according to claim 10, wherein the picture information display element is provided with information signals through a line sequential driving, and a direction of the line sequential driving is identical with the second direction.

12. A projection type display device according to claim 1, wherein the light from the light source is deflected to irradiate a region of the picture information display element, and an entire area of the picture information display element is irradiated with the light by scanning the region of the picture information display element to be irradiated with the light in the horizontal and vertical directions in a specified timing within each frame period.

13. A projection type display device according to claim 1, wherein the picture information display element is a liquid crystal display element.

14. A projection type display device according to claim 13, wherein the liquid crystal display element is a reflective type liquid panel.

15. A projection type display device according to claim 13, wherein the liquid crystal display element is a transmissive type liquid panel.

16. A projection type display device according to claim 13, wherein the liquid crystal display element uses a liquid crystal display mode having characteristics in which an average molecular axis of the liquid crystal indicates a monostabilized position when no voltage is applied, wherein the average molecular axis of the liquid crystal tilts to a first direction from the monostabilized position at an angle according to the magnitude of a voltage of a first polarity applied, the average molecular axis of the liquid crystal tilts to a second direction opposite the first direction from the monostabilized position at an angle according to the magnitude of a voltage of a second polarity that is an opposite polarity of the first polarity applied, and a maximum tilt angle β

1 of the average molecular axis of the liquid crystal upon application of the voltage of the first polarity and a maximum tilt angle β

2 of the average molecular axis of the liquid crystal upon application of the voltage of the second polarity with respect to a position of the average molecular axis of the liquid crystal in the monostabilized position satisfy a relation of β

1<

β

2, and wherein the liquid crystal display element has active elements that are line sequentially scanned.

17. A projection type display device according to claim 1, wherein the picture information display element displays picture information by changing the reflecting angle of a mirror surface present on each pixel to control the light on/off state.

18. A projection type display device according to claim 1, wherein the light deflection device is a polygon mirror.

19. A projection type display device according to claim 1, further comprising a function to change a scanning speed of the light deflection device according to display picture information.

20. A projection type display device according to claim 1, further comprising a picture processing function to change a scanning speed of the light deflection device and give a picture information signal to the picture information display element according to the scanning speed.

21. A projection type display device according to claim 1, wherein the light deflection device irradiates the light on an area outside of an effective display area of the picture information display element.

22. A projection type display device according to claim 21, further comprising a function to change a scanning speed of the light deflection device according to picture information and control a period in which the area outside the effective display area is irradiated with the light according to a luminance level of the picture information.

23. A projection type display device according to claim 1, wherein the light source is a point light source.