Fresnel lens, screen, image displaying device, lens forming mold manufacturing method and lens manufacturing method

A Fresnel lens, in which a ray of incident light having a prescribed incident angle goes out through a prism portion as a ray of outgoing light having a prescribed outgoing angle for each pitch area, comprising:

• a plurality of pitch areas respectively having a hybrid type prism portion which has both a refraction type prism portion and a total reflection prism portion integrally formed with each other, wherein
• a sectional shape of the refraction type prism portion of each pitch area is formed by:
• a first incident plane for changing a ray of first incident light incident at a prescribed incident angle to a ray of first transmitted light according to a first refraction phenomenon;
• a plane-shaped outgoing plane for changing the ray of first transmitted light obtained on the first incident plane to a ray of first outgoing light having a prescribed outgoing angle according to a second refraction phenomenon;
• and
• an ineffective plane connecting with the first incident plane and an adjacent pitch area, a sectional shape of the total reflection type prism portion of each pitch area is formed by:
• a second incident plane for changing a ray of second incident light incident at the prescribed incident angle to a ray of second transmitted light according to a third refraction phenomenon;
• a total reflection plane for changing the ray of second transmitted light obtained on the second incident plane to a ray of third transmitted light parallel to the ray of first transmitted light according to a total reflection phenomenon;
• and
• the ray of third transmitted light obtained in the total reflection plane is changed to a ray of second outgoing light having the prescribed outgoing angle according to a fourth refraction phenomenon on the outgoing plane, and
• a portion of the ray of second incident light not changed to the ray of third transmitted light is received as the ray of first incident light.

A Fresnel lens, comprising:

• a plurality of total reflection type prism portions which are arranged on a light incident side and respectively have both a second incident plane, on which a plurality of rays of light are incident, and a total reflection plane, on which a part of the rays of light are totally reflected and are deflected in a desired direction,
• wherein each total reflection type prism portion has a subsidiary unit-prism portion arranged in a part of the second incident plane on which a ray of light expected not to be totally reflected on the total reflection plane is incident, and
• the subsidiary unit-prism portion functions as a refraction type prism portion having a first incident plane on which the ray of incident light is refracted to be deflected in the desired direction;
• wherein a plane obtained by extending the first incident plane of each subsidiary unit-prism portion is placed in a position shifted from the total reflection plane toward a light outgoing side in a range of the corresponding total reflection type prism portion.

A Fresnel lens, comprising:

• a plurality of total reflection type prism portions which are arranged on a light incident side and respectively have both a second incident plane, on which a plurality of rays of light are incident, and a total reflection plane, on which a part of the rays of light are totally reflected and are deflected in a desired direction,
• wherein each total reflection type prism portion has a subsidiary unit-prism portion arranged in a part of the second incident plane on which a ray of light expected not to be totally reflected on the total reflection plane is incident, and
• the subsidiary unit-prism portion functions as a refraction type prism portion having a first incident plane on which the ray of incident light is refracted to be deflected in the desired direction;
• wherein a ratio of each subsidiary unit-prism portion to the corresponding second incident plane differs from those of the other subsidiary unit-prism portions.

A Fresnel lens, comprising:

• a first region in which a plurality of total reflection type prism portions which are arranged on a light incident side and respectively have both a second incident plane, on which a plurality of rays of light are incident, and a total reflection plane, on which a part of the rays of light are totally reflected and are deflected in a desired direction,
• wherein each total reflection type prism portion has a subsidiary unit-prism portion arranged in a part of the second incident plane on which a ray of light expected not to be totally reflected on the total reflection plane is incident, and
• the subsidiary unit-prism portion functions as a refraction type prism portion having a first incident plane on which the ray of incident light is refracted to be deflected in the desired direction;
• and
• a second region in which a plurality of refraction type prism portions respectively having both a first incident plane, on which a ray of incident light is refracted to be deflected in a desired direction, and an ineffective plane different from the first incident plane are arranged on a light incident side,
• wherein each refraction type prism portion has a subsidiary unit-prism portion arranged on the first incident plane, a ray of light expected to be incident on the ineffective plane of another adjacent refraction type prism portion placed on a Fresnel periphery side is received in the subsidiary unit-prism portion, and the subsidiary unit-prism portion functions as a total reflection type prism portion having both a second incident plane, on which a ray of light is received, and a total reflection plane on which the ray of light received on the second incident plane is totally reflected to be deflected in the desired direction.

A Fresnel lens, comprising:

• a plurality of total reflection type prism portions which are arranged on a light incident side and respectively have both a second incident plane, on which a plurality of rays of light are incident, and a total reflection plane, on which a part of the rays of light are totally reflected and are deflected in a desired direction,
• wherein each total reflection type prism portion has a subsidiary unit-prism portion arranged in a part of the second incident plane on which a ray of light expected not to be totally reflected on the total reflection plane is incident, and
• the subsidiary unit-prism portion functions as a refraction type prism portion having a first incident plane on which the ray of incident light is refracted to be deflected in the desired direction;
• wherein a second Fresnel lens different from the Fresnel lens arranged on a plane of the light incident side is arranged on a plane of a light outgoing side of the Fresnel lens.

A screen, comprising:

• a Fresnel lens including
• a plurality of refraction type prism portions which are arranged on a light incident side and respectively have both a first incident plane, on which a ray of incident light is refracted to be deflected in a desired direction, and an ineffective plane different from the first incident plane,
• wherein each refraction type prism portion has a subsidiary unit-prism portion arranged on the first incident plane, a ray of light expected to be incident on the ineffective plane of another adjacent refraction type prism portion placed on a Fresnel periphery side is received in the subsidiary unit-prism portion, and
• the subsidiary unit-prism portion functions as a total reflection type prism portion having both a second incident plane, on which a ray of light is received, and a total reflection plane on which the ray of light received on the second incident plane is totally reflected to be deflected in the desired direction,
• a plane-shaped outgoing plane which transmits the light from the total reflection plane and the first incident plane;
• and
• a light diffusing means, arranged on the outgoing plane.