Image display device and portable terminal device using the same

1. An image display device comprising:

a display panel which has a plurality of pixel sections provided in the form of a matrix, each pixel section including at least a pixel for displaying a first image and a pixel for displaying a second image, wherein said first image is different from said second image;

a lens disposed in front of said display panel, said lens being constituted by a plurality of lens elements, each of said plurality of lens elements corresponding to each pixel section, a direction of refracting light from each pixel for said first image being different from a direction of refracting light from each pixel for said second image; and

a reflection plate disposed in said display panel or in the rear of said display panel, said reflection plate having surface projections on the surface thereof for reflecting exterior light to said lens;

wherein the focal distance f of said lens is different from the distance H between the surface of said reflection plate and the apex of said lens.

2. An image display device according to claim 1 , wherein the focal distance f of said lens is smaller than the distance H between the surface of said reflection plate and the apex of said lens.

3. An image display device according to claim 2 , wherein the focal distance f of said lens and the distance H between the surface of said reflection plate and the apex of the lens fulfill the following expression:

H/f≧V/L+ 1

where L is the pitch of convex portions on the surface of said lens in a first direction extending toward said pixel for displaying said image for said second viewpoint from said pixel for displaying said image for said first viewpoint and V is the minimum pitch of the surface projections in said reflection plate in said first direction.

4. An image display device according to claim 3 , wherein the focal distance f of said lens fulfills the following expressions in the case when an optimal observation distance of the thee-dimensional image display device is OD; an expanded projection width of the pixel at a distance of OD is e; a refraction index of said lens is n; and a pitch of the pixels in each of the pixel sections is P:

β= arc tan( e/OD )

α= arc sin(1/ n ·sin β)

f=P /tan α

5. An image display device according to claim 3 , wherein an optimal observation distance OD, an expanded projection width e of the pixel, a refraction index n of said lens, a distance H between the surface of said reflection plate and the center of the convex portion on the surface of the lens and a pitch P of the pixels in each of the pixel sections fulfill the following expressions:

β= arc tan( e/OD )

α= arc sin(1/ n ·sin β)

H=P /tan α

6. An image display device according to claim 1 , wherein a focal distance f of said lens is larger than a distance H between the surface of said reflection plate and the apex of the lens.

7. An image display device according to claim 6 ,

wherein the focal distance f of said lens, the distance H between the surface of said reflection plate and the apex of the lens, said lens pitch L and the minimum pitch V of said surface projections fulfill the following expression:

H/f≦−V/L+ 1

where L is the pitch of convex portions on the surface of said lens in a first direction extending toward said pixel for displaying said second image from said pixel for displaying said first image and V is the minimum pitch of the surface projections in said reflection plate in said first direction.

8. An image display device according to claim 7 , wherein an optimal observation distance OD, an expanded projection width e of the pixel, a refraction index n of said lens, the focal distance f of said lens and a pitch P of the pixels in each of the pixel sections fulfill the following expressions:

β= arc tan( e/OD )

α= arc sin(1 /n ·sin β)

f=P /tan α

9. An image display device according to claim 7 , wherein an optimal observation distance OD, an expanded projection width e of the pixel, a refraction index n of said lens, the distance H between the surface of said reflection plate and the apex of the lens and a pitch P of the pixels in each of the pixel sections fulfill the following expressions:

β= arc tan( e/OD )

α= arc sin(1/ n ·sin β)

H=P /tan α

10. An image display device according to claim 1 , wherein said lens is a lenticular lens.

11. An image display device according to claim 1 , wherein said lens is a fly-eye lens.

12. An image display device according to claim 1 , wherein said image for said first viewpoint is an image for the left eye and said image for said second viewpoint is an image for the right eye which has a parallax with respect to said image for the right eye to thereby provide a three-dimensional image.

13. An image display device according to claim 1 , wherein said display device is a liquid crystal display device.

14. A portable terminal device including a three-dimensional image display device according to claim 1 .

15. An image display device according to claim 14 , wherein said portable terminal device is a cellular phone, portable terminal, PDA, game machine, digital camera, or digital video camera.

16. An image display device comprising:

a display panel which has a plurality of pixel sections provided in the form of a matrix, each pixel section including at least a pixel having a transmissive region and a reflective region for displaying a first image and a pixel having a transmissive region and a reflective region for displaying a second image, wherein said first image is different from said second image;

a lens disposed in front of the display panel, said lens being constituted by a plurality of lens elements, each of said plurality of lens elements corresponding to each pixel section, a direction of refracting light from each pixel for said first image being different from a direction of refracting light from each pixel for said second image;

a light source illuminating the transmissive region of said display panel with the light; and

a reflection plate disposed in the reflective region of said display panel or in the rear of the reflective region of said display panel, said reflection plate having surface projections on the surface thereof for reflecting exterior light to said lens;

wherein the focal distance f of said lens is different from the distance H between the surface of said reflection plate and the apex of said lens.

17. An image display device according to claim 16 , wherein the focal distance f of said lens is smaller than the distance H between the surface of said reflection plate and the apex of said lens.

18. An image display device according to claim 17 , wherein the focal distance f of said lens and the distance H between the surface of said reflection plate and the apex of the lens fulfill the following expression:

H/f≧V/L+ 1

where L is the pitch of convex portions on the surface of said lens in a first direction extending toward said pixel for displaying said image for said second viewpoint from said pixel for displaying said image for said first viewpoint and V is the minimum pitch of the surface projections in said reflection plate in said first direction.

19. An image display device according to claim 18 , wherein the focal distance f of said lens fulfills the following expressions in the case when an optimal observation distance of the three-dimensional image display device is OD; an expanded projection width of the pixel at a distance of OD is e; a refraction index of said lens is n; and a pitch of the pixels in each of the pixel sections is P:

β= arc tan( e/OD )

α= arc sin(1/ n ·sin β)

f=P /tan α

20. An image display device according to claim 18 , wherein an optimal observation distance OD, an expanded projection width e of the pixel, a refraction index n of said lens, a distance H between the surface of said reflection plate and the center of the convex portion on the surface of the lens and a pitch P of the pixels in each of the pixel sections fulfill the following expressions:

β= arc tan( e/OD )

α= arc sin(1/ n ·sin β)

H=P /tan α

21. An image display device according to claim 16 , wherein a focal distance f of said lens is larger than a distance H between the surface of said reflection plate and the apex of the lens.

22. An image display device according to claim 21 ,

wherein the focal distance f of said lens, the distance H between the surface of said reflection plate and the apex of the lens, said lens pitch L and the minimum pitch V of said surface projections fulfill the following expression:

H/f≦−V/L+ 1

where L is the pitch of convex portions on the surface of said lens in a first direction extending toward said pixel for displaying said second image from said pixel for displaying said first image and V is the minimum pitch of the surface projections in said reflection plate in said first direction.

23. An image display device according to claim 22 , wherein an optimal observation distance OD, an expanded projection width e of the pixel, a refraction index n of said lens, the focal distance f of said lens and a pitch P of the pixels in each of the pixel sections fulfill the following expressions:

β= arc tan( e/OD )

α= arc sin(1/ n ·sin β)

f=P /tan α

24. An image display device according to claim 22 , wherein an optimal observation distance OD, an expanded projection width e of the pixel, a refraction index n of said lens, the distance H between the surface of said reflection plate and the apex of the lens and a pitch P of the pixels in each of the pixel sections fullfill the following expressions:

β= arc tan( e/OD )

α= arc sin(1/ n ·sin β)

H=P /tan α

25. An image display device according to claim 16 , wherein said lens is a lenticular lens.

26. An image display device according to claim 16 , wherein said lens is a fly-eye lens.

27. An image display device according to claim 16 , wherein said image for said first viewpoint is an image for the left eye and said image for said second viewpoint is an image for the right eye which has a parallax with respect to said image for the right eye to thereby provide a three-dimensional image.

28. An image display device according to claim 16 , wherein said display device is a liquid crystal display device.

29. A portable terminal device including a three-dimensional image display device according to claim 16 .

30. An image display device according to claim 29 , wherein said portable terminal device is a cellular phone, portable terminal, PDA, game machine, digital camera, or digital video camera.