The present invention relates to a stacked disk-shaped optical lens array, a stacked disk-shaped lens module array and methods of manufacturing the same, especially to a stacked disk-shaped optical lens array having at least two disk-shaped optical lens arrays stacked precisely with a required disk-shaped optical element array to produce a stacked disk-shaped lens module array used in LED arrays, lens module arrays of solar energy conversion systems, etc.
The resin injection-compression molding technology has been widely applied to various optical produces with high requirements of precision, size and optical properties such as DVD, CD-ROM, or optical lenses. The resin injection-compression molding combines two techniques-injection molding and compression molding. A mold compression process is added into general injection molding processes. That means during the beginning of the resin casting process, the mold is not closed completely. The mold is closed by pressure after part of resin being filled into a mold cavity. The pressure is applied to melt resin material inside the mold cavity through the casting area. The processes are called “closing and clamping mold operations” and the mold cavity filling is finished by compression molding. Compared with injection molding, the residual stress is reduced, the difference in refractive index is decreased, and the optical lens element is with higher accuracy. As shown in US2008/0093756, JP2008-230005, JP2003-071874 etc., optical lens elements are produced by such molding method.
Optical lenses have been broadly used in camera lenses, LED distributing lens and concentrating lenses of solar energy conversion systems. In manufacturing optical lens arrays, JP2001194508 disclosed a method for manufacturing plastic optical lens array while TW M343166 revealed a method for manufacturing glass optical lens array. In manufacturing lens module arrays, U.S. Pat. No. 7,183,643, US2007/0070511, WO2008011003 etc revealed a wafer level lens module. Refer to FIG. 1, an ordinary optical lens module array includes an aperture 911, a cover glass 912, a plurality of optical lens elements and an IR cut glass 917. As shown in figure, it is a three-piece type optical lens set includes a first optical lens element, a second optical lens element and a third optical lens element 914, 915, 916, spaced by a spacer 913. After assembly, a lens module array is produced.
While assembling optical lenses or producing optical lenses, a plurality of optical lens elements with different refractions is assembled with certain air spacing for images. Thus optical axis of each optical lens element needs to be aligned precisely so as to prevent reduced resolution. Moreover, there is a certain distance arranged between the optical lens elements. It takes a lot of time and efforts to run processes and precise alignment. Thus the production can't be boosted and the cost can't be reduced. Especially the assembling of the optical lens array will influence the optical effects once the optical axis of the optical lens array is not aligned. Thus the alignment of the optical lens array is getting more important and more complicated. Refer to US2006/0249859, it revealed fiducial marks generated by infrared rays to assemble wafer level lens module. Refer to JP2000-321526, and JP2000-227505, a SELFOC lenses array is produced by assembling of height with cervice. Refer to JP2001-042104, recesses with different depth are used to prevent warpage and deformation of the micro lens array. As to U.S. Pat. No. 7,187,501, cone-shaped projection is used to stack multiple optical lens elements and produce a plastic optical lens array. Refer to FIG. 2, an optical lens module array 900 includes three optical lens arrays 910, 920, 930, each disposed with projections 915 and holes 925. By the projections 915 connected with the holes 925, the optical lens module array 900 is produced. However, the projections 915 and the holes 925 are used for mechanical positioning not for optical alignment. Thus the optical axis of each optical lens element of the optical lens array is not aligned. Furthermore, refer to FIG. 3, an optical lens module array 900 consists of two glass lens arrays 910, 920, respectively with at least one alignment cavity 915 and at least one alignment pin 925. By connection of the alignment cavity 915 with the alignment pin 925, the optical lens module array 900 is formed. The alignment cavity 915 and the alignment pin 925 can be integrated with the glass lens arrays 910, 920 by glass molding. And an optical axis of each optical lens element of the optical lens module array is aligned.
The optical lens module array used in lens assemblies of LED (light emitting diode) light sources, lens assemblies of solar energy systems, and lens modules of mobile cameras generally includes a plurality of optical lens arrays with different optical surfaces. In conventional plastic optical lens arrays assembled by projections and holes, the plastic optical lens arrays are produced by injection molding, the size of the projections and holes may change due to material shrinkage. Thus the alignment accuracy is difficult to be improved. And the optical axis of each optical lens in the plastic optical lens array is shifted and difficult to be aligned. This results in restrictions on use.
A disk-shaped optical lens array produced by resin injection-compression molding and resin casting process through a center of a disk has low inner stress and high accuracy. Moreover, a disk hole arranged at a center of the disk-shaped optical lens array is used for alignment while assembling. Thus an easy method of manufacturing an optical lens module array with high accuracy by the disk-shaped optical lens array is provided. The produced optical lens module array is used in LED arrays or lens module arrays of solar energy conversion systems, matching requirements of yield rate and production of mass production.
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