RELATED APPLICATIONS This application is a continuation-in-part of U.S. patent application Ser. No. 11/182,205, filed on Jul. 15, 2005.
BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to optics. More specifically, the present invention discloses an array of lenses for high-resolution imaging of a surface.
2. Description of the Prior Art
Traditionally, the lens for a one to one imaging optical scanner is a rod lens array. Please refer to FIG. 1, a perspective drawing of a prior-art rod lens array 100. The rod lens array 100 is constructed from a plurality of fiber optic rod lenses 110. Each individual fiber optic rod lens 110 is cut from a fiber optic glass strand, and its ends must be polished. The plurality of fiber optic rod lenses 110 are then arranged side by side, in a row or multiple rows with their optical axes in parallel, in a frame 120 and held in place by an adhesive layer 130. The fiber optic rod lenses 110 are typically made from GRIN (graduated index) fibers, with the refractive index of the glass carefully controlled during manufacture to have a graduated refractive index that decreases radially from the central axis to the edge.
However, this type of lens is expensive to manufacture. GRIN type fiber optic glass strands are expensive in and of themselves; cutting and polishing the strands to precise lengths to form fiber optic rod lenses 110, assembling them so that their axes are precisely parallel in the frame 120, and gluing the fiber optic rod lenses 110 are all precision steps for which entire technologies have had to be developed in order to satisfy requirements.
In addition, a major disadvantage of this type of lens is that because of the number of lenses and the difficulty in orienting them, it is not practical to shape the ends of the lenses so that they can magnify the surface that they are imaging; flat ends are used. In order to increase the imaging resolution, it is necessary to use larger numbers of smaller-diameter rod lenses 110, limiting the maximum resolution and driving up the costs as the desired resolution increases. Furthermore, suppliers for the necessary GRIN fiber optic strands are limited, and thus the base materials themselves are expensive.
Therefore there is need for an improved lens array for which materials are substantially cheaper and which is simpler to manufacture, and which can have increased resolution without substantially increasing costs.
SUMMARY OF THE INVENTION To achieve these and other advantages and in order to overcome the disadvantages of the conventional method in accordance with the purpose of the invention as embodied and broadly described herein, the present invention provides a lens array where pluralities of lens faces are molded into surfaces of polymer bars, thus simplifying manufacturing, using inexpensive materials, and aligning the lenses without requiring significant manufacturing infrastructure.
The present invention further provides a lens array where the lens faces are configurable at the time of design to support increased resolution.
These and other objectives of the present invention will become obvious to those of ordinary skill in the art after reading the following detailed description of preferred embodiments.
It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed.
BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. In the drawings:
FIG. 1 is a perspective drawing of a prior art rod lens array;
FIG. 2 is an exploded perspective drawing of a lens array of the present invention;
FIG. 3a is a drawing of a surface of a stop for a lens array of the present invention with the view in line with the optical axis;
FIG. 3b is a drawing of a surface of a spacer for a lens array of the present invention with the view in line with the optical axis;
FIG. 3c is a drawing of a surface of a spacer for a lens array of the present invention with the view in line with the optical axis;
FIG. 4a is a drawing of a first surface of a first lens section for a lens array of the present invention with the view in line with the optical axis;
FIG. 4b is a drawing of a second surface of a first lens section for a lens array of the present invention with the view in line with the optical axis;
FIG. 4c is a drawing of a cross-section of a first lens section for a lens array of the present invention along the long axis;
FIG. 5 is a drawing of a cross-section of a first lens section for a lens array of the present invention across a width of the first lens section;
FIG. 6a is a drawing of a second surface of a first lens section for a lens array of the present invention with the view in line with the optical axis;
FIG. 6b is a drawing of an end of a second surface of a first lens section for a lens array of the present invention with the view in line with the optical axis;
FIG. 6c is a drawing of a cross-section of a first end of a first lens section for a lens array of the present invention along the long axis;
FIG. 6d is a drawing of a cross-section of a second end of a first lens section for a lens array of the present invention along the long axis;
FIG. 7a is a drawing of a first surface of a second lens section for a lens array of the present invention with the view in line with the optical axis;
FIG. 7b is a drawing of a second surface of a second lens section for a lens array of the present invention with the view in line with the optical axis;
FIG. 7c is a drawing of a cross-section of a second lens section for a lens array of the present invention along the long axis;
FIG. 8a is a drawing of a first surface of a second lens section for a lens array of the present invention with the view in line with the optical axis;
FIG. 8b is a drawing of a cross-section of an end of a second lens section for a lens array of the present invention along the long axis;
FIG. 9 is a drawing of a cross-section of a second lens section for a lens array of the present invention across a width of the second lens section;
FIG. 10a is a detail drawing of a first end of a surface of a stop for a lens array of the present invention with the view in line with the optical axis;
FIG. 10b is a detail drawing of a second end of a surface of a stop for a lens array of the present invention with the view in line with the optical axis;
FIG. 10c is a detail drawing of an end of a surface of a spacer for a lens array of the present invention with the view in line with the optical axis;
FIG. 10d is a detail drawing of an end of a surface of a spacer for a lens array of the present invention with the view in line with the optical axis;
FIG. 11a is a perspective drawing of a lens array of the present invention;
FIG. 11b is a drawing of a lens array of the present invention mounted to a printed circuit board, with the view in line with the optical axis;
FIG. 11c is a cross-section drawing of a lens array of the present invention mounted to a printed circuit board, along the long axis;
FIG. 12a is a top view of a lens array of the present invention in a frame mounted to a printed circuit board;
FIG. 12b is a cross-section drawing of a lens array of the present invention in relation to a printed circuit board, along the long axis;
FIG. 12c is a cross-section drawing of a lens array of the present invention in relation to a printed circuit board, across the width of the lens array and printed circuit board;
FIG. 13A is a top view drawing of a first lens section according to an embodiment of the present invention;
FIG. 13B is a cross sectional view drawing of a first lens section according to an embodiment of the present invention;
FIG. 13C is a bottom view drawing of a first lens section according to an embodiment of the present invention;
FIG. 13D is a 3-dimensional drawing of a first lens section according to an embodiment of the present invention;
FIG. 14A is a cross sectional view drawing of a second housed lens according to an embodiment of the present invention;
FIG. 14B is a bottom view drawing of a second housed lens according to an embodiment of the present invention;
FIG. 14C is a side view drawing of a second housed lens according to an embodiment of the present invention;
FIG. 14D is a top view drawing illustrating a second housed lens according to an embodiment of the present invention;
FIG. 14E is a 3-dimensional drawing of a second housed lens according to an embodiment of the present invention;
FIG. 15A is a cross sectional view of the lens array assembly according to an embodiment of the present invention;
FIG. 15B is a top view of the first housed lens of the lens array assembly according to an embodiment of the present invention;
FIG. 15C is a side view of the lens array assembly according to an embodiment of the present invention;
FIG. 15D is a bottom view of the second housed lens of the lens array assembly according to an embodiment of the present invention;
FIG. 15E is a 3-dimensional drawing illustrating the lens array assembly according to an embodiment of the present invention; and
FIGS. 16A and 16B are cross sectional views illustrating light pathways through a lens array assembly according to an embodiment of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts.
Please refer to FIG. 2, which shows an exploded perspective drawing of a lens array of the present invention. The lens array 200 of this embodiment consists of a stop 240, a first lens section 210, three spacers 221,222,223, and a second lens section 230. Each component is discussed in further detail below. The number of spacers may vary between embodiments depending on design considerations. Only one spacer is required, but two or more may be used; the example embodiment uses three spacers. A frame (not shown) may optionally enclose the perimeter of the assembled lens array 200, providing support, mounting, and protection, and blocking external light.
Please refer momentarily to FIG. 6b, which is a cross-section drawing of a lens array of the present invention in relation to a printed circuit board. This figure will be discussed in greater detail later; until then, note the distance 201 between the optical axes of two adjacent lens surfaces, referred to hereafter as the inter-axis distance 201.
Please refer to FIG. 3a, which is a drawing of a surface of a stop for a lens array of the present invention with the view in line with the optical axis, in combination with FIG. 10a and FIG. 10b, which are detail drawings of the same part as marked in FIG. 3a by A and B respectively. The stop 240 has a plurality of holes 241 organized such that the centers of the holes form a line down the center of the spacer. The first plurality of holes 241 are spaced apart equally by the inter-axis distance. The first plurality of holes 241 are circular, oval, cylindrical, or conical. Along the edges of the stop 240, a plurality of notches 242 is positioned to mate with a plurality of ears 211e of the first surface 211 of the first lens section 210. A locating hole 243 near one end of the stop 240 is sized and positioned to fit around the phasing post 351 of the first lens array.
Please refer to FIG. 3b, which is a drawing of a surface of a spacer for a lens array of the present invention with the view in line with the optical axis, in combination with FIG. 10c, which is a detail of one end of the part as marked in FIG. 3b by C. The third spacer 223 is substantially identical to the first spacer 221 and is not shown separately here. The first and third spacers 221,223 have a plurality of holes 410 organized such that the centers of the holes form a line down the center of the spacer. The holes 410 are spaced apart equally by one inter-axis distance 201. The holes 410 may be tapered right conic frustums or they may be cylindrical. Along the sides of the spacer 220, a plurality of notches 420 is positioned to mate with the ears 211e of the lens arrays. A locating hole 430 near one end of the first and third spacers 221,223 is sized and positioned to fit around the phasing post 350 of the second lens array. The locating hole 430 and the plurality of notches 420 serve to locate and hold the first and third spacers 221,223 in alignment with the first and/or second lens sections 210,230 so that the centers of the holes 410 are centered on the lens axes. The minimum diameter of the holes 410 is the outer diameter of the lens faces molded into the surface against which the spacer is disposed.
FIG. 3c is also a drawing of a surface of a spacer for a lens array of the present invention with the view in line with the optical axis, in combination with FIG. 10d, which is a detail of the same part, noted in FIG. 3c by D. The spacer 222 is similar to the first spacer 221 and third spacer 223 except that the diameter of the plurality of holes 411 are smaller. The plurality of holes 411 are spaced apart equally by one inter-axis distance 201. The notches 421 are the same size as the notches 420 of the spacers 221,223.
Please refer to FIG. 4a, which is a drawing of a first surface of a first lens section for a lens array of the present invention with the view in line with the optical axis. Two section lines A-A and B-B are marked for use in FIG. 4c and FIG. 5 respectively. FIG. 4a shows the first surface 211 of the first lens section 210. The first surface 211 has a channel 211c down the center of the lens, and a first plurality of lens surfaces 213 are formed with their optical axes in line, spaced apart equally by one inter-axis distance 201. The line of the centers of the first plurality of lens surfaces 213 in this example embodiment is along the center line of the channel 211c. A plurality of ears 211e is formed along the edges 211a, 211b of the first lens surface 211 of the first lens section 210, such that the ears 211e are sized and spaced to mate with the notches 242 of the stop 240. The width of the first lens section 210 is substantially the same as the width of the stop 240. A first post 211p is located at one end of the first lens section 210, sized and positioned to mate with the locating hole 243 of the stop 240. A surface of the stop 240 fits snugly against the faces of the edges 211a,211b with notches 242 mating to ears 211e so that the plurality of holes 241 of the spacer 240 are lined up with their centers on the optical axes of the first plurality of lens surfaces 213. The locating hole 243 and the plurality of notches 242 serve to locate and hold the stop 240 in alignment with the first lens section 210 so that the centers of the holes 241 are substantially on the optical axes of the first plurality of lens surfaces 213.
Please refer to FIG. 4b, which is a drawing of a second surface of a first lens section for a lens array of the present invention with the view in line with the optical axis, in combination with FIG. 6a and FIG. 6b, which are detail drawings of the same part as marked by C and D in FIG. 4a, respectively. These figures show the second surface 212 of the first lens section 210. The second surface 212 has a channel 212c down the center of the lens, and a second plurality of lens surfaces 214 are formed with their optical axes in line, spaced apart equally by one inter-axis distance 201. The line of the centers of the first plurality of lens surfaces 213 in this example embodiment is along the center line of the channel 212c. A plurality of ears 212e is formed along the edges 212a, 212b of the first lens surface 212 of the first lens section 210, such that the ears 212e are sized and spaced to mate with the notches 420 of the first spacer 221. The width of the first lens section 210 is substantially the same as the width of the first spacer 221. A first hole 212h is located and sized to mate with a second post 231p (see FIG. 7a, FIG. 7c, and FIG. 8b) of the second lens section 230 (see FIG. 7a, FIG. 7b, FIG. 7c, FIG. 8a, FIG. 8b, and FIG. 9). A surface of the first spacer 221 fits snugly against the faces of the edges 212a,212b with notches 420 mating to ears 212e so that the plurality of holes 410 are lined up with their centers on the optical axes of the second plurality of lens surfaces 214.
Please refer to FIG. 4c, which is a drawing of a cross-section of a first lens section for a lens array of the present invention along the long axis, in combination with FIG. 6c and FIG. 6d, which are detail drawings of the same part for the details marked in FIG. 4c by E and F respectively. The cross-section view also shows the distal portion of the lens in the background. The cross-section cuts across the first plurality of lens surfaces 213 and the second plurality of lens surfaces 214, as well as the first post 211p and first hole 212h. The second edges 211b, 212b and ears 211e, 212e are visible in the background, behind the channels 211c, 212c. In FIG. 6c, a first post 211p for positioning a stop 240 is located on the first surface 211. Several first lens surfaces of the first plurality of lens surfaces 213 are located in the channel 211c. Several second lens surfaces of the second plurality of lens surfaces 214 are located in the channel 212c. In FIG. 6d, the first hole 212h is located in the second surface 212. The plurality of optical axes of the first plurality of lens surfaces 213 are inline with the plurality of optical axes of the second plurality of lens surfaces 214. Please note that the optical axes of the second plurality of lens surfaces 214 are aligned with the optical axes of the first plurality of lens surfaces 213 and that the number of lens surfaces in the first plurality of lens surfaces 213 is the same as the number of lens surfaces in the second plurality of lens surfaces 214.
Please refer to FIG. 5, which is a cross-section drawing of a first lens section for a lens array of the present invention across a width of the first lens section. This cross-section cuts along the optical axes of a pair of lens surfaces consisting of one of the first plurality of lens surfaces 213 in channel 211c and one of a lens surface of the second plurality of lens surfaces 214 in channel 212c, two ears of the plurality of ears 211e, and two ears of the plurality of ears 212e. Visible in the background is the first post 211p. Edges 211a and 211b, against which the stop 240 (not shown) will be placed when assembled, are shown. Edges 212a and 212b, against which the first spacer 221 will be placed when assembled, are also shown.
Please refer to FIG. 7a, which is a drawing of a third surface of a second lens section for a lens array of the present invention with the view in line with the optical axis, in combination with FIG. 8a, which is a detail of the same part for the region marked in FIG. 7a by C. Two section lines A-A and B-B are marked for use in FIG. 7c and FIG. 9 respectively. FIG. 7a shows the third surface 211 of the second lens section 230. The third surface 231 has a channel 231c down the center of the lens, and a third plurality of second lens surfaces 233 are formed with their optical axes in line, spaced apart equally by one inter-axis distance 201. The line of the centers of the third plurality of lens surfaces 233 in this example embodiment is along the center line of the channel 231c. A plurality of ears 231e is formed along the edges 231a, 231b of the second lens surface 231 of the second lens section 230, such that the ears 231e are sized and spaced to mate with the notches 410 of the first spacer 221, the notches 411 of the second spacer 222, and the notches 410 of the third spacer 223. In this embodiment, the ears 231e are substantially longer than the ears 212e on the first lens section 210, and mate with the notches on all three spacers, compared with the first lens section 210 only mating with the notches on the first spacer 221, but this is implementation-dependent and may vary in practice. The width of the second lens section 230 is substantially the same as the width of the first spacer 221, second spacer 222, and third spacer 223. A second post 231p is located at one end of the second lens section 230, sized and positioned to mate with the locating hole 430 of the first spacer 221, the locating hole 431 of the second spacer 222, the locating hole 430 of the third spacer 223, and the first hole 212h of the first lens section 210. This second post 231p is stepped down in diameter since the locating holes 430,431,430 are larger in diameter than the first hole 212h (see further discussion for FIG. 8b). A surface of the third spacer 223 fits snugly against the faces of the edges 231a,231b with notches 420 mating to ears 231e so that the plurality of holes 410 are lined up with their centers on the optical axes of the third plurality of lens surfaces 233.
Please refer to FIG. 7b, which is a drawing of a second surface of a second lens section for a lens array of the present invention with the view in line with the optical axis. FIG. 7b shows the second surface 232 of the second lens section 230. The second surface 232 has a channel 232c down the center of the lens, and a fourth plurality of lens surfaces 234 are formed with their optical axes in line, spaced apart equally by one inter-axis distance 201. The line of the centers of the third plurality of lens surfaces 233 in this example embodiment is along the center line of the channel 232c. The edges to the sides 232a, 232b help protect the fourth plurality of lens surfaces 234 from handling damage during manufacture.
Please refer to FIG. 7c, which is a drawing of a cross-section of a second lens section for a lens array of the present invention along the long axis, in combination with FIG. 8b, which is a detail of the same part as marked in drawing 7c by D. The cross-section view also shows the distal portion of the lens in the background. The cross-section cuts across the third plurality of lens surfaces 233 and the fourth plurality of lens surfaces 234, as well as the second post 231p, which has a section of a first diameter 231p1 and a section of a second diameter 231p2. The section 231p1 is larger in diameter than the section 231p2; the section 231p1 is designed to mate with the locating holes 430,431,430 in the first spacer 221, second spacer 222, and third spacer 223 respectively. The section 231p2 is designed to mate with the first hole 212h of the first lens section 210. The second edges 231b, 232b and ears 231e are visible in the background, behind the channels 231c, 232c. Please note that the optical axes of the third plurality of lens surfaces 233 are aligned with the optical axes of the fourth plurality of lens surfaces 234 and that the number of lens surfaces in the third plurality of lens surfaces 233 is the same as the number of lens surfaces in the fourth plurality of lens surfaces 234.
Please refer to FIG. 11a, a perspective drawing of a lens array of the present invention, in combination with FIG. 12b and FIG. 12c, cross sections of a lens array of the present invention. The lens array 200 is assembled with a frame 250 (not shown) so that it is held at a fixed distance from a sensor 260 which is mounted on a printed-circuit board (PCB) 270. The stop 240 is positioned against the first surface 211 of the first lens section 210. The first spacer 221 is positioned with one face against the second surface 212 of the first lens section 210, with its notches 420 aligned with and held in place by the ears 212e, which extend only partially through the depth of the plurality of notches 420 of the first spacer 221; one face of the second spacer 222 is positioned against the other face of the first spacer 221; and then one face of the third spacer 223 is positioned against the other face of the second spacer 222; finally, the other face of the third spacer 223 is positioned against the third surface 231 of the second lens section 230. The second post 231p of the second lens section 230 fits its larger-diameter segment 231p1 through the locating holes 430,431,430 of the first spacer 221, second spacer 222, and third spacer 223 respectively; and the longer ears 231e of the second lens section 230 fit through the notches 420,421,420 of the first spacer 221, second spacer 222, and third spacer 223 respectively. The smaller-diameter segment 231p2 of the second post 231p fits into the first hole 212h of the second surface 212 of the first lens section 210. The ears 231e of the second lens section 230 abut the ears of the first lens section 210. The ears, posts, holes, and notches combine to hold the stop 240, the three spacers 221,222,223, and the two lens sections 210,230 in alignment.
Referring now to FIG. 11b, a top view of the lens array of the present invention assembled with a PCB, in combination with FIG. 12a, a detail view of the same assembly, as marked on FIG. 11b by B. A cross-section used in FIG. 11c and FIG. 12b is marked with the section line A-A. The lens array 200 is assembled inside a frame 250 which secures the lens to the PCB 270. The stop 240 is fitted against the first surface, and the first plurality of lens surfaces 213 of the first surface 211 of the first lens section 210 is visible through the plurality of holes 241 in the stop.
The lens surfaces of the first plurality of lens surfaces 213 have identical diameters and optical radii. The lens surfaces of the second plurality of lens surfaces 214 have identical diameters and optical radii. The lens surfaces of the third plurality of lens surfaces 233 have identical diameters and optical radii. The lens surfaces of the fourth plurality of lens surfaces 234 have identical diameters and optical radii. The four pluralities of lens surfaces 213,214,233,234 are identical in number and in the center-to-center spacing of the lens faces. The four pluralities of holes 410,411,410,241 from the first spacer 221, second spacer 222, third spacer 223, and stop 240 also are identical both in number and in the center-to-center spacing of the holes to the four pluralities of lens surfaces. As shown in FIG. 12b, the optical axes of the four pluralities of lens surfaces, and the centers of the four pluralities of holes, are all aligned, thus forming a single plurality of lens units. Each quad of four lens faces, one from each of the four pluralities above, positioned on the same optical axis forms a lens unit with a lens axis. One embodiment for imaging A4 sized paper at 300 dpi has 330 lens units. Note that there is no restriction on the configuration of the lens units; although this example embodiment shows an array in a single line, two or more lines of lens units can be used, organized in a square grid, or a rectangular grid, or hexagonally.
Please refer to FIG. 11c, a cross-section view of the lens array of the present invention assembled with a PCB, in combination with FIG. 12b, a detail view of the same assembly, as marked on FIG. 11c by C. A line at the top of FIG. 12b represents the object plane 280, which corresponds to a surface to be imaged. The stop 240 is proximal to the object plane 280, along with the first plurality of lens surfaces 213. The plurality of lens surfaces gathers and focuses light reflected from the surface so that the light travels in a divergent beam through the first lens section to the second plurality of lens surfaces 214. The light is generated by an external source. The first spacer 221, second spacer 222, and third spacer 223 block and absorb scattered light, while the pluralities of holes 420,421,420 allow desired, focused light to reach the third plurality of lens surfaces 233. The light then transits the second lens section and exits through the fourth plurality of lens surfaces 234, which focuses the light onto the sensor 260 mounted on the PCB 270.
In the preferred embodiment, the first lens section and second lens section are preferably made of a refractive, substantially transparent polymer. The spacer(s), stop, and frame are preferably made of an opaque polymer, preferably black, to absorb and/or block undesirable scattered or external light. One or more spacers can be used; using fewer spacers reduces manufacturing costs.
Refer to FIG. 13A, which is a top view drawing of a first lens section according to an embodiment of the present invention; to FIG. 13B, which is a cross sectional view drawing of a first lens section according to an embodiment of the present invention; to FIG. 13C, which is a bottom view drawing of a first lens section according to an embodiment of the present invention; and to FIG. 13D, which is a 3-dimensional drawing of a first lens section according to an embodiment of the present invention.
In an embodiment of the present invention, the lens array comprises two housed lens; a first housed lens and a second housed lens. Both of the housed lens comprise a plurality of lens disposed on the top and bottom surfaces of the lens sections.
As shown in FIGS. 13A-13D, the first housed lens 1300 comprises a plurality of first lenses 1330 on the top surface of the first lens section 1320 and a plurality of second lenses 1340 on the bottom surface of the first lens section 1320. As in the previous embodiments, the lens section is transparent.
In this embodiment, the first lens section 1320 is encased in a first lens housing 1310. The first lens housing 1310 is made of black plastic or other light absorbing material. The first lens housing 1310 has holes which expose the plurality of first lenses 1330 and second lenses 1340. The first lens housing 1310 further comprises a plurality of slots 1350.
In the previous embodiments, the spacers prevented unwanted light from entering the lenses. In the embodiment illustrated in FIGS. 13A-13D, the edges of the holes in the first lens housing 1310 extend all the way to the edges of the lenses 1330 1340. Additionally, the thickness of the first lens housing 1310 is greater than the spacers in the previous embodiments.
In production, the lens section is molded and then placed into another mold as an insert and the lens housing is molded around the lens section.
Refer to FIG. 14A, which is a cross sectional view drawing of a second housed lens according to an embodiment of the present invention; to FIG. 14B, which is a bottom view drawing of a second housed lens according to an embodiment of the present invention; to FIG. 14C, which is a side view drawing of a second housed lens according to an embodiment of the present invention; to FIG. 14D, which is a top view drawing illustrating a second housed lens according to an embodiment of the present invention, and to FIG. 14E, which is a 3-dimensional drawing of a second housed lens according to an embodiment of the present invention.
As shown in FIGS. 14A-14E, the second housed lens 1400 comprises a plurality of first lenses 1430 on the top surface of the second lens section 1420 and a plurality of second lenses 1440 on the bottom surface of the second lens section 1420. As in the previous embodiments, the lens section is transparent.
In this embodiment, the second lens section 1420 is encased in a second lens housing 1410. The second lens housing 1410 is made of black plastic or other light absorbing material. The second lens housing 1410 has holes which expose the plurality of first lenses 1430 and second lenses 1440. The second lens housing 1410 further comprises a plurality of tabs 1460.
Refer to FIG. 15A, which is a cross sectional view of the lens array assembly according to an embodiment of the present invention; to FIG. 15B, which is a top view of the first housed lens of the lens array assembly according to an embodiment of the present invention; to FIG. 15C, which is a side view of the lens array assembly according to an embodiment of the present invention; to FIG. 15D, which is a bottom view of the second housed lens of the lens array assembly according to an embodiment of the present invention; and to FIG. 15E, which is a 3-dimensional drawing illustrating the lens array assembly according to an embodiment of the present invention.
As shown in FIGS. 15A-15E, the tabs of the second lens housing mate with the plurality of slots of the first lens housing. The mating tabs and slots hold the first housed lens 1300 and second housed lens 1400 together to form the lens array assembly 1500.
Refer to FIGS. 16A and 16B, which are cross sectional views illustrating light pathways through a lens array assembly according to an embodiment of the present invention.
When the lens array assembly is used in an image scanner, it is very important that image light does not pass from one lens into another lens that is not perpendicular to it. When this light progresses into an adjacent lens, the resultant image that the sensor captures is a ghost image of the adjacent lens. This is called cross-talk and is undesirable.
An advantage of the present invention is that due to the wall thickness of the first and second lens housings and the housings extend to the edges of the individual lenses, cross-talk is prevented.
As shown in FIG. 16B, if the lens assembly doesn't have a suitable lens housing, light can pass between lenses and result in ghosting. However, as shown in FIG. 16A, if light passes from one lens into the hole of the housing, the light is absorbed by the wall of the housing thus preventing the undesirable light from entering the adjacent lens. As a result, cross-talk is eliminated and ghosting is prevented.
As shown in FIGS. 13-16, the holes in the top and bottom of the first lens housing and the holes in the top of the second lens housing encircle the lenses of the first lens section and the second lens section. Also, little or no gap exists between the lens sections between the lenses and the lens housings.
The dots per inch (DPI) resolution of the lens array is adjustable at design time by changing the optical radii, conic constant, or aspherical coefficients of the four lens groups. In contrast with the prior art rod lenses, the lens array can be designed to magnify the surface being imaged. The lens surface is defined by the formula:
for each of the two lens sections.
The lens array thus provides a substantial improvement over the prior art by reducing manufacturing complexity and materials costs. Furthermore, the lens array makes it substantially less difficult to increase the resolution of a device using the lens array compared to the prior art.
It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the invention and its equivalent.
