Optical: systems and elements – Single channel simultaneously to or from plural channels – By surface composed of lenticular elements
Reexamination Certificate
2000-03-30
2001-09-25
Epps, Georgia (Department: 2873)
Optical: systems and elements
Single channel simultaneously to or from plural channels
By surface composed of lenticular elements
C359S621000
Reexamination Certificate
active
06295165
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to an erect image magnifying lens device, particularly to an erect image magnifying lens device utilizing a microlens array.
BACKGROUND OF THE INVENTION
One example of a conventional erect image lens devices for magnifying displayed image is a device in which a plurality of distributed-index rod lenses are arranged in one dimension. In this erect image magnifying lens device, each optical axis of the rod lenses is arranged in an angle so as to implement desired magnification of the lens device, and the working distance of each rod lens is adjusted in such a manner that images passed through respective rod lenses are formed on a same plane.
Another example of a conventional erect image magnifying lens device comprises the combination of an erect image, unity magnification lens and a fresnel lens, the erect image, unity magnification lens consisting of a plurality of distributed-index rod lenses arranged in two dimensions on the same plane.
FIG. 1
shows such an erect image magnifying lens device. The lens device
8
comprises an erect image, unity magnification lens
10
consisted of a plurality of distributed-index rod lenses arranged in two dimensions on the same plane, a concave fresnel lens
12
positioned within the working distance of the rod lens, a display element
14
, and an image plane
16
.
According to the lens device
8
, the light emitted from the display element
14
is transmitted through the rod lenses
10
, is refracted by the concave fresnel lens
12
, and reaches to the image plane
16
on which a large magnified image is formed.
In the first conventional lens device comprising the plurality of distributed-index rod lenses arranged in one dimension, it is impossible to form a two-dimensional device because the adjustment of the optical axis angle and the working distance of the rod lens is difficult.
In the second conventional lens device comprising the combination of the erect image, unity magnification lens and the concave fresnel lens, it is difficult to obtain higher magnification since the magnification obtained is only 1.1-1.2 by refracting the light within the working distance of the erect image, unity magnification lens with the concave fresnel lens. When a plurality of erect image magnifying lens devices are arranged in two dimensions to form an image display apparatus having a large screen, if the magnification of the erect image magnifying lens device is low, it is difficult to make a display element small so that the cost of the lens device becomes high. Also, if the light is caused to be refracted by the concave fresnel lens in a large angle so as to obtain a higher magnification, there is a problem such that an image displayed around the peripheral portion of an image plane gets blurred.
While the both of conventional lens devices have the construction utilizing rod lenses, the processing for rod lenses is very difficult.
The object of the present invention, therefore, is to provide an erect image magnifying lens device which may obtain a higher magnification.
Another object of the present invention is to provide an erect image magnifying lens device having a superior image forming capability without decreasing an image quality of the peripheral portion of an image plane.
Still another object of the present invention is to provide an erect image magnifying lens device using a micro-lens array which may be easily formed by a molding process.
SUMMARY OF THE INVENTION
The present invention is directed to an erect image magnifying lens device. This lens device comprises a display element for displaying an image; a fresnel lens provided on the display element for refracting a light emitted by the display element to a direction to magnify the image; an erect image magnifying lens consisted of stacked two micro-lens arrays and positioned in opposition to the fresnel lens; and an image plane positioned in opposition to the errect image magnifying lens, on which the image from the display element is formed.
Each of the micro-lens arrays has a number of spherical micro-lenses arrayed in X-Y matrix on at least one side thereof. At least three spherical micro-lenses may be aligned on a given one of the optical axes of the erect image magnifying lens.
The array pitches of the spherical micro-lenses on respective sides of the two micro-lens arrays are selected so that any of the optical axes which pass through at least three spherical micro-lenses of the erect image magnifying lens are crossed through the back focus of the fresnel lens.
When the angle in which the light emitted from the display element and passed through the fresnel lens goes into the spherical surface of micro-lens without becoming stray light is defined as “an incident angle &dgr;”, the incident angle &dgr; is determined by the dimension of spherical micro-lens. Assuming that an angle between a given optical axis and a main axis line is “an optical axis angle &thgr;”, an incident light which is matched to the incident angle &dgr; at a given optical axis angle &thgr; comes from the first fresnel lens.
REFERENCES:
patent: 6128054 (2000-10-01), Schwarenberger
patent: 6133687 (2000-10-01), Clarke
patent: 2000284217-A (2000-10-01), None
Kishimoto Takashi
Nemoto Hiroyuki
Epps Georgia
Nippon Sheet Glass Co. Ltd.
Ratner & Prestia
Seyrafi Saeed H
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