Optical: systems and elements – Single channel simultaneously to or from plural channels – By surface composed of lenticular elements
Reexamination Certificate
2002-06-10
2004-09-21
Mack, Ricky (Department: 2873)
Optical: systems and elements
Single channel simultaneously to or from plural channels
By surface composed of lenticular elements
C359S619000
Reexamination Certificate
active
06795250
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to a lenticular lens array for producing visual effects from interdigitated or interlaced images. More particularly, the present invention relates to a lenticular lens array where a cross section of each lens element on the array comprises an elliptical shape. The present invention also relates to a tool and a method for creating such a lenticular lens array.
BACKGROUND OF THE INVENTION
A lenticular lens can create visual animated effects for interdigitated or interlaced (hereinafter “interlaced”) printed images. The images can be printed using non-impact printing, known as masterless printing, or by conventional printing processes, known as master printing. Typically, a lenticular lens application comprises two major components: an extruded, cast, or embossed plastic lenticular lens and the interlaced printed image. The front of the lenticular lens comprises a plurality of lenticules arranged in a regular array, having cylindrical lens elements running parallel to one another. The back of the lenticular lens is flat and smooth. The interlaced images are printed on the flat, smooth backside of the lenticular lens. Exemplary methods for printing the images include conventional printing methods such as screen, letterpress, flexographic, offset lithography, and gravure; and non-impact printing methods such as electro-photography, iconography, magnetography, ink jet, thermography, and photographic. Any of the above printing technologies can be used in either sheet-fed or roll web-fed forms.
The interlaced images are viewed individually, depending on the angle through which a viewer observes the images through the lenticular lens elements. At a first viewing angle, a first image appears through the lenticular lens elements. As the lenticular lens is rotated, the first image disappears and another image appears through the lenticular lens elements. Viewing the images through the lenticular lens elements can create the illusion of motion, depth, and other visual effects. A lenticular lens can create those illusions through different visual effects. For example, the visual effects can comprise three-dimensions (3-D), animation or motion, flip, morph, zoom, or combinations thereof.
For a 3-D effect, multiple layers of different visual elements are interlaced together to create the illusion of 3-D, distance, and depth. For example, background objects are pictured with foreground objects that appear to protrude when viewed through a straight forward, non-angled view. For an animation or motion effect, a series of sequential photos can create the illusion of animated images. A viewer observes the series of photos as the viewing angle of the lens changes. Animation is effective in showing mechanical movement, body movement, or products in use.
For a flip visual effect, two or more images flip back and forth as the viewing angle changes. The flip effect can show before-and-after and cause-and-effect scenarios. It also can show bilingual messages, such as flipping from English to Spanish. For a morph visual effect, two or more unrelated images gradually transform or morph into one another as the viewing angle of the lenticular lens changes. Finally, for a zoom effect, an object moves from the background into the foreground as the viewing angle of the lenticular lens changes. The object also may travel from side to side, but usually works better in a top to bottom format.
FIG. 1
illustrates a partial cross section of a conventional lenticular lens array
100
. The array
100
comprises lenticules
102
,
104
,
106
. Each lenticule
102
,
104
,
106
comprises a cylindrical lens element
102
a
,
104
a
,
106
a
, respectively. Each lens element
102
a
,
104
a
,
106
a
operates to focus light on a back surface
107
of the array
100
. In operation of the conventional array
100
, multiple images can be printed on the rear surface
107
. An observer can singularly view the images through the lens elements
102
a
,
104
a
,
106
a
by rotating the array
100
.
Specific characteristics of each lenticule
102
,
104
,
106
will be described with reference to exemplary lenticule
104
. Each lens element
102
a
,
104
a
,
106
a
has a circular cross section of radius R. The circular cross section corresponds to a desired circular shape
108
having the radius R. The lens element
104
a
comprises a portion of the circular shape
108
. Lenticule
104
also has a distance t from a vertex of the lens element
104
a
to the rear surface
107
of the array
100
. The lens element
104
a
has a lens junction depth d where it joins adjacent lens elements
102
a
,
106
a
. Finally, the material forming the lens array
100
determines a refractive index N of the array
100
.
The relationship between the distance t, the radius R, and the refractive index N is given by the following equation:
t
=
R
N
N
-
1
(
1
)
As shown in equation (1), the thickness t and radius R are a function of the refractive index N, which is a function of wavelength of light. Accordingly, the lenticular lens elements can be optimized for a particular wavelength based on the wavelength that provides the best overall performance for the desired application.
Regularity of the array
100
can be defined by the separation or distance S between the vertex of adjacent lens elements. For the conventional cylindrical lenticular lens array
100
, the maximum separation between the vertex of each lens element
102
a
,
104
a
,
106
a
is given by the following equation:
S
max
=2
R
(2)
A pitch P of the lenticules can be defined as a number of lenticules per unit length (lpu). For example, the unit length can comprise an inch or a millimeter. For the conventional cylindrical lenticular lens array
100
, the minimum pitch is given by the following equation:
P
min
=
1
2
R
[
lpu
]
(
3
)
FIG. 2
illustrates a light ray trace illustrating several problems associated with a conventional lenticular lens array
100
. In general, the array
100
operates by passing light from the rear surface
107
through the lens elements
102
a
,
104
a
,
106
a
to an observer. Reciprocity allows viewing the light path in reverse as illustrated in FIG.
2
. Ideally, on-axis light L
1
passes through lens element
104
a
and is focused to a common point
202
on the rear surface
107
of the array
100
. However, the circular cross-section of the lens element
104
a
produces a projected image having spherical aberration. For example, the light L
1
is projected over a large area
204
on the rear surface
107
. The large projection area limits resolution and the number of interlaced images that can be viewed on the rear surface
107
.
Additionally, off-axis light L
2
passes through the lens element
104
a
and is focused upon the rear surface
107
near point
203
. However, the circular cross-section of lens element
104
a
produces coma and an astigmatic aberration
208
. Finally, FIG.
2
illustrates that the depth d of the lens surface can approach the radius of the circular cross-section at the junction of adjacent lenses. Accordingly, portions of the light L
2
are blocked by lens
106
a
and may be redirected to the wrong location
206
.
FIG. 3
illustrates a light beam projection illustrating another problem associated with the conventional lenticular lens array
100
.
FIG. 3
illustrates light beams projected to an observer from different printed areas of the conventional lenticular lens array
100
. As shown, the light beams in the central area
302
are not reasonably matched over the circular angle of the lens.
Furthermore, conventional lenticular sheet-fed printing has been used to create promotional printed advertising pieces printed on a lenticular lens array. For example, the advertising pieces include limited volumes of thicker gauge lenticular material designs such as buttons, signage, hang tags for clothing, point-of-purchase displays, postcards, greeting cards, telephone cards, trading cards, credit cards, and the like. Those thick
Jacobsen Gary A.
Johnson Ralph Barry
King & Spalding LLP
LentiClear Lenticular Lens, Inc.
Mack Ricky
LandOfFree
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