Projection type liquid-crystal video display device using a fresnel lens

Claim 2

A projection-type liquid-crystal video display device, comprising: an illuminating light source; a nematic liquid-crystal display panel for transmitting said illuminating light, a reorientation angle of axes of liquid crystals in said display panel being inclined at a predetermined angle with respect to electrodes when a voltage is applied to said display panel; a projection optical system for projecting said transmitted light onto a screen, said optical system having an entrance pupil; and an optical element disposed on an emergence side of said liquid crystal panel for refracting the light emitted obliquely relative to said liquid crystal display in accordance with said reorientation angle of said liquid crystals, to optically converge the light in close proximity of said entrance pupil of said optical system, said optical element having on at least one surface thereof of Fresnel lens having an optical axis offset from an optical axis of said optical system.

Claim 3

A display device as recited in claim 1, wherein said optical element comprises two crossed linear Fresnel lenses orthogonally oriented to each other, at least one of said Fresnel lenses being eccentric with respect to a center line.

Claim 4

A display device as recited in claim 2, wherein said eccentric linear Fresnel lens has a spherical base.

Claim 5

A display device as recited in claim 2, wherein said eccentric linear Fresnel lens has a non-spherical base.

Claim 6

A display device as recited in claim 1, wherein said optical element comprises a circular Fresnel lens being eccentric with respect to a center point.

Claim 7

A display device as recited in claim 5, wherein said eccentric circular Fresnel lens has a spherical base.

Claim 8

A display device as recited in claim 5, wherein said eccentric circular Fresnel lens has a non-spherical base.

Claim 9

A projection-type liquid-crystal video display device, comprising: an illuminating light source; a nematic liquid-crystal display panel for transmitting said illuminating light, a reorientation angle of axes of light crystals of said display panel being inclined at a predetermined angle with respect to electrodes when a voltage is applied to said display panel; a projection optical system for projecting said transmitted light onto a screen, said optical system having an entrance pupil; and an optical element disposed on an emergence side of said liquid crystal panel for refracting the light emitted obliquely relative to said liquid crystal display in accordance with said reorientation angle of said liquid crystals, to optically converge the light in close proximity of said entrance pupil of said optical system, said optical element having a circular Fresnel lens on one surface and a stepped prism with a saw-toothed cross-section on the other.

Claim 10

A projection-type liquid-crystal video display device, comprising: an illuminating light source; a nematic liquid-crystal display panel for transmitting said illuminating light, a reorientation angle of axes of light crystals of said display panel being inclined at a predetermined angle with respect to electrodes when a voltage is applied to said display panel; a projection optical system for projecting said transmitted light onto a screen, said optical system having an entrance pupil; and an optical element disposed on an emergence side of said liquid crystal panel for refracting the light emitted obliquely relative to said liquid crystal display in accordance with said reorientation angle of said liquid crystals, to optically converge the light in close proximity of said entrance pupil of said optical system, said optical element having a circular Fresnel lens on one surface and a stepped prism with a saw-toothed cross-section on the other.

Claim 11

A display device as recited in claim 8, wherein said circular Fresnel lens has a spherical base.

Claim 12

A display device as recited in claim 8, wherein said circular Fresnel lens has a non-spherical base.

Claim 13

A projection-type liquid-crystal video display device, comprising: an illuminating light source; a nematic liquid-crystal display panel for transmitting said illuminating light, a reorientation angle of axes of liquid crystals of said display panel being inclined at a predetermined angle with respect to electrodes when a voltage is applied to said display panel; a projection optical system for projecting said transmitted light onto a screen, said optical system having an entrance pupil; a first optical element disposed adjacent on an emergence side of said liquid crystal panel for refracting the light emitted obliquely relative to said liquid crystal display in accordance with said reorientation angle of said liquid crystals, to optically converge the light in close proximity of said entrance pupil of said optical system, said optical element having on at least one surface thereof a Fresnel lens having an optical axis offset from an optical axis of said optical system; and a second optical element disposed on incident side of said liquid crystal panel for introducing the light, emitted from said illuminating light source, into said crystal display panel substantially in parallel with the reorientation angle of axes of the liquid crystals.

Claim 14

A projection-type liquid-crystal video display device, comprising: an illuminating light source; a nematic liquid-crystal display panel for transmitting said illuminating light, a reorientation angle of axes of liquid crystals of said display panel being inclined at a predetermined angle with respect to electrodes when a voltage is applied to said display panel; a projection optical system for projecting said transmitted light onto a screen, said optical system having an entrance pupil; a first optical element disposed adjacent on an emergence side of said liquid crystal panel for refracting the light emitted obliquely relative to said liquid crystal display in accordance with said reorientation angle of said liquid crystals, to optically converge the light in close proximity of said entrance pupil of said optical system, said optical element having on at least one surface thereof a Fresnel lens having an optical axis offset from an optical axis of said optical system; and a second optical element disposed on incident side of said liquid crystal panel for introducing the light, emitted from said illuminating light source, into said crystal display panel substantially in parallel with the reorientation angle of axes of the liquid crystals.

Claim 15

A display device as recited in claim 11, wherein said second optical element comprises a collimation lens having an optical axis inclined with respect to said display panel.

Claim 16

A display device as recited in claim 11, wherein said second optical element comprises a collimation lens and a stepped prism having a saw-toothed cross-section.

Claim 17

A display device as recited in claim 11, wherein said second optical element comprises a circular Fresnel lens and a stepped prism having a saw-toothed cross-section.

Claim 18

A display device as recited in claim 11, wherein said second optical element comprises a collimation lens and prism.

Claim 19

A display device as recited in claim 14, wherein said circular Fresnel lens has a spherical base.

Claim 20

A display device as recited in claim 14, wherein said circular Fresnel lens has a non-spherical base.

Claim 21

A display device as recited in claim 11, wherein said second optical element comprises two crossed linear Fresnel lenses orthogonally oriented to each other, at least one of said linear Fresnel lens being eccentric with respect to a center line.

Claim 22

A display device as recited in claim 18, wherein said eccentric linear Fresnel lens has a spherical base.

Claim 23

A display device as recited in claim 18, wherein said eccentric linear Fresnel lens has a non-spherical base.

Claim 24

A display device as recited in claim 18, wherein said second optical element comprises a circular Fresnel lens eccentric with respect to a center.

Claim 25

A display device as recited in claim 21, wherein said eccentric circular Fresnel lens has a spherical base.

Claim 26

A display device as recited in claim 21, wherein said eccentric circular Fresnel lens has a non-spherical base.

Claim 27

A display device as recited in claim 11, wherein said second optical element comprising an off-axis mirror facing said source of illuminating light for reflecting light at a inclined angle toward said display panel.

Claim 28

A projection-type liquid-crystal video display device, comprising: an illuminating light source; a nematic liquid-crystal display panel for transmitting said illuminating light, a reorientation angle of axes of liquid crystals in said display panel being inclined at a predetermined angle with respect to electrodes when a voltage is applied to said display panel; a projection optical system for projecting said transmitted light onto a screen, said optical system having an entrance pupil; a first optical element disposed on an emergence side of said liquid crystal panel for refracting the light emitted obliquely relative to said liquid crystal display in accordance with said reorientation angle of said liquid crystals, to optically converge the light in close proximity of said entrance pupil of said optical system, said optical element having a circular Fresnel lens on one surface and a stepped prism with a saw-toothed cross-section on the other; and a second optical element disposed on incident side of said liquid crystal panel for introducing the light, emitted from said illuminating light source, into said crystal display panel substantially in parallel with the reorientation angle of axes of the liquid crystals.

Claim 29

A projection-type liquid-crystal video display device, comprising: an illuminating light source; a nematic liquid-crystal display panel for transmitting said illuminating light, a reorientation angle of axes of liquid crystals in said display panel being inclined at a predetermined angle with respect to electrodes when a voltage is applied to said display panel; a projection optical system for projecting said transmitted light onto a screen, said optical system having an entrance pupil; a first optical element disposed on an emergence side of said liquid crystal panel for refracting the light emitted obliquely relative to said liquid crystal display in accordance with said reorientation angle of said liquid crystals, to optically converge the light in close proximity of said entrance pupil of said optical system, said optical element having a circular Fresnel lens on one surface and a stepped prism with a saw-toothed cross-section on the other; and a second optical element disposed on incident side of said liquid crystal panel for introducing the light, emitted from said illuminating light source, into said crystal display panel substantially in parallel with the reorientation angle of axes of the liquid crystals.