Claims
- 1. A focusing screen made from a plate of optical material, comprising:
- a plurality of small lens portions disposed on a surface of said plate, said plurality of small lens portions projecting from said surface in an array of equilateral triangles; and
- a flat portion formed around a periphery of each of said small lens portions;
- wherein each of said plurality of small lens portions has an inclined surface extending from said periphery of said small lens portion to an apex thereof, said inclined surface having a constricted portion.
- 2. A focusing screen as recited in claim 1, each of said small lens portions having concentric contour lines and an apex located at the center of said lens portion.
- 3. A focusing screen as recited in claim 2, wherein said focusing screen satisfies the following condition:
- 90<(n-1).P.theta.<130
- where .theta.=tan.sup.-1 (Hmax/D), in which n is the refractive index of said optical material, P is the distance between said apexes of adjacent ones of said small lens portions, Hmax is the height of said apexes, wherein the direction of projection is positive with respect to said flat portion, and D is the radius of said small lens portions.
- 4. A focusing screen as recited in claim 2, wherein said focusing screen satisfies the following condition:
- 0.8<H.sub.0.2D /Hmax<1
- 0.4<H.sub.0.4D /Hmax<0.8
- 0.2<H.sub.0.6D /Hmax<0.6
- 0.1<H.sub.0.8D /Hmax<0.5
- where Hmax is the height of said apexes of said small lens portions, wherein the direction of projection is positive with respect to said flat portion, and D is the radius of said small lens portions, and H.sub.0.2D, H.sub.0.4D, H.sub.0.6D, and H.sub.0.8D, are the heights of contour lines having radii 0.2 D, 0.4 D, 0.6 D, and 0.8 D, respectively.
- 5. A focusing screen as recited in claim 2, wherein said focusing screen satisfies the following condition:
- 0.35<D/P<0.5
- where P is the distance between said apexes of adjacent ones of said small lens portions, and D is the radius of said small lens portions.
- 6. A focusing screen as recited in claim 1, wherein said flat portion is formed so as to be devoid of high spots and low spots.
- 7. A focusing screen as recited in claim 1, wherein said constricted portion is disposed in a middle portion of said inclined surface between an upper and lower portion, said constricted portion having a less steep inclination than said upper and lower portions of said inclined surface.
- 8. A focusing screen as recited in claim 1, wherein each of said plurality of small lens portions and said flat portion has an irregular pattern of finer asperities formed thereon.
- 9. A focusing screen made from a plate of optical material, comprising:
- a plurality of small lens portions disposed on a surface of said plate, said plurality of small lens portions being recessed into said surface in an array of equilateral triangles; and
- a flat portion formed around a periphery of each of said small lens portions;
- wherein each of said plurality of small lens portions has an inclined surface extending from said periphery of said small lens portion to a valley thereof, said inclined surface having a bulging portion.
- 10. A focusing screen as recited in claim 9, each of said small lens portions having concentric contour lines and a valley located at the center of said small lens portion.
- 11. A focusing screen as recited in claim 10, wherein said focusing screen satisfies the following condition:
- 90<(n-1).P.theta.<130
- where .theta.=tan.sup.-1 (Hmax/D), in which n is the refractive index of said optical material, P is the distance between said valleys of adjacent ones of said small lens portions, Hmax is the depth of said valleys, wherein the direction of projection is positive with respect to said flat portion, and D is the radius of said small lens portions.
- 12. A focusing screen as recited in claim 10, wherein said focusing screen satisfies the following condition:
- 0.8<H.sub.0.2D /Hmax<1
- 0.4<H.sub.0.4D /Hmax<0.8
- 0.2<H.sub.0.6D /Hmax<0.6
- 0.1<H.sub.0.8D /Hmax<0.5
- where Hmax is the depth of said valleys of said small lens portions, wherein the direction of projection is positive with respect to said flat portion, and D is the radius of said small lens portions, and H.sub.0.2D, H.sub.0.4D, H.sub.0.6D, and H.sub.0.8D, are the depths of contour lines having radii 0.2 D, 0.4 D, 0.6 D, and 0.8 D, respectively.
- 13. A focusing screen as recited in claim 10, wherein said focusing screen satisfies the following condition:
- 0.35<D/P<0.5
- where P is the distance between said valleys of adjacent ones of said small lens portions, and D is the radius of said small lens portions.
- 14. A focusing screen as recited in claim 9, wherein said flat portion is formed so as to be devoid of high spots and low spots.
- 15. A focusing screen as recited in claim 9, wherein said bulging portion is disposed in a middle portion of said inclined surface between an upper and lower portion, said bulging portion having a less steep inclination than said upper and lower portions of said inclined surface.
- 16. A focusing screen as recited in claim 9, wherein each of said plurality of small lens portions and said flat portion has an irregular pattern of finer asperities formed thereon.
Priority Claims (1)
Number |
Date |
Country |
Kind |
63-106540 |
Apr 1988 |
JPX |
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Parent Case Info
This is a continuation of application Ser. No. 07/564,270 filed on Aug. 8, 1990, now abandoned which is a continuation of application No. 07/280,902 filed Dec. 7, 1988, now abandoned.
US Referenced Citations (6)
Foreign Referenced Citations (2)
Number |
Date |
Country |
3125205 |
Mar 1982 |
DEX |
3125317 |
Apr 1982 |
DEX |
Non-Patent Literature Citations (1)
Entry |
"Investigation and Application of Photographic Micro-Lenticular Rasters", Deml et al. Optik 37 pp. 439-450, Sep. 1972. |
Continuations (1)
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Number |
Date |
Country |
Parent |
564270 |
Aug 1990 |
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Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
280902 |
Dec 1988 |
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