RELATED APPLICATION The present application claims the benefit of US provisional application

61/167,226 filed on April 7 ^th , 2009, the disclosure of which is incorporated herein by reference.

FIELD OF THE INVENTION The present invention relates to imaging systems, and more particularly, the present invention relates to a method of manufacturing an imaging system from two or more image sensors having defective pixels.

BACKGROUND OF THE INVENTION AND PRIOR ART In the production of image sensors, often, one or more pixels of the produced image sensor are defective. The image sensor arrays are scanned and all detected defective pixels are sorted out, mapped and marked. In some types of image sensors such a defective image sensor is rejected. In other types of image sensors such a defective image sensor is computed from the adjacently surrounding pixels, for example, from the 4 or 8 adjacently surrounding pixels.

For Example, the yield of infra red (IR) image sensors is very low - about 0.1 -5%, due to defective pixels. Therefore, there is a need for and it would be advantageous to have a method to substantially raise the production yield of image sensors, such as infra red image sensors.

SUMMARY OF THE INVENTION

According to teachings of the present invention, there is provided a method of manufacturing an image sensor from two defective image sensor arrays having identical structural design, each having substantially the same field of view (FOV) and aligned to view substantially the same scene. The method includes providing a first defective image sensor array, having known defective pixels, providing a second defective image sensor array, having known defective pixels, and fusing the first image sensor array and the second image sensor array into a single output image array. For each of the defective pixels of the first image sensor array the respective pixel from the second image sensor array is selected to be an output pixel of the output image array. For each of the defective pixels of the second image sensor array the respective ^' pixel from the first image sensor array is selected to be an output pixel of the output image array. For each valid pixel in the first image sensor array, having a respective valid pixel in the second image sensor array, either of the respective valid pixels is selected to be an output pixel of the output image array.

Preferably, the first defective image sensor array and the second defective image sensor array have no overlapping defective pixels. In variations of the present invention, if the first defective image sensor array and the second defective image sensor array have overlapping defective pixels, then for each of the overlapping defective pixels, setting the value of a corresponding final output pixel in the output image array to be the average of the K immediately adjacent neighboring pixels of the overlapping defective pixel, in the output image array. In some variations of the present invention, K=4. In other variations of the present invention, K=8.

According to further teachings of the present invention, there is provided a computerized image acquisition system. The system includes a first image sensor array having defective pixels, a second image sensor array having defective pixels, and an image fusion module. The first image sensor array and the second image sensor array have substantially the same FOV and are aligned to view substantially the same scene. For each of the defective pixels of the first image sensor array, the image fusion module selects the respective pixel from the second image sensor array to be an output pixel of an output image array. For each of the defective pixels of the second image sensor array, the ^' image fusion module selects the respective pixel from the first image sensor array to be an output pixel of the output image array. For each valid pixel in the first image sensor array having a respective valid pixel in the second image sensor array, the image fusion module selects either of the respective valid pixels to be an output pixel of the output image array.

Preferably, the first defective image sensor array and the second defective image sensor array have no overlapping defective pixels. In variations of the present invention, if the first defective image sensor array and the second defective image sensor array have overlapping defective pixels, then for each of the overlapping defective pixels, the image fusion module sets the value of a corresponding final output pixel in the output image array to be the average of the K immediately adjacent neighboring pixels of the overlapping defective pixel, in the output image array. In some variations of the present invention, K=4. In other variations of the present invention, K=8. In variations of the present invention, if the first defective image sensor array and the second defective image sensor array have overlapping defective pixels that have partial light energy sensitivity, a weighted average of the partially defective pixels is computed. The weights are directly proportional to the partial light energy sensitivity of each of the partially defective pixels. The computed weighted average is then assigned to the corresponding output pixel.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become fully understood from the detailed description given herein below and the accompanying drawings, which are given by way of illustration and example only and thus not limitative of the present invention, and wherein:

FIG. 1 is a block diagram illustration of a camera system, according to embodiments of the present invention, built from two defective image sensors;

FIG. 2 is a block diagram illustration of a camera system, according to variations of the present invention;

FIG. 3 illustrates examples of a defective pixel having immediately adjacent valid pixels; and

FIG. 4 illustrates examples beam splitter configuration for camera systems according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided, so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The methods and examples provided herein are only illustrative and not intended to be limiting. By way of introduction, a principal intention of the present invention includes providing a method for producing an imaging system having two or more defective image sensors, yielding a single logical valid image sensor.

Reference is made to Figure 1, which is a block diagram illustration of exemplary imaging system 100, according to embodiments of the present invention. Imaging system 100 includes two defective image acquisition devices 110a and 110b, each of which' includes respective an image sensor array, 130a and 130b, and an image fusion module 140 wherein the methodology of image fusion module 140 yields a single output image frame 150. Both image acquisition devices 110 have substantially the same FOV and pointing substantially to the same distal object 20. Image fusion module 140 selects valid pixels from either image sensors 130a and 130b to yield a single output image frame 150.

It should be noted that the manufacturing method of the present invention, substantially increases the image sensors production, for example, the yield of IR image sensors may increase to over 90%.

Preferably, image sensor arrays 130a and 130b are selected such that there are no respective pairs of pixels, where both pixels are defective.

The methodology of image fusion module 140 may be embodied in various methods. In a first embodiment, the methodology of image fusion module 140 includes the following steps: a) selecting image sensor 130a as the primary image sensor and image sensor 130b as the secondary image sensor; and b) for each pair of respective pixels, performs the following steps: i. if the pixel of the primary image sensor is valid, setting the value of the corresponding output pixel in image frame 150 to be the value of the pixel of the primary image sensor; else ii. setting the value of the corresponding output pixel in image frame 150 to be the value of the pixel of the secondary image sensor. In a second embodiment, the methodology of image fusion module 140 includes the following steps: a) selecting image sensor 130b as the primary image sensor and image sensor 130a as the secondary image sensor; and b) for each pair of respective pixels, performs the following steps: i. if the pixel of the primary image sensor is valid, setting the value of the corresponding output pixel in image frame 150 to be the value of the pixel of the primary image sensor; else ii. setting the value of the corresponding output pixel in image frame 150 to be the value of the pixel of the secondary image sensor.

Reference is made to Figure 2, which is a block diagram illustration of exemplary imaging system 200, according to variations of the present invention. As in system 100, imaging system 200 includes two defective image acquisition devices HOa and 110b,' each of which includes respective an image sensor array, 130a and 130b. Both image acquisition devices 110 have substantially the same FOV and pointing substantially to the same distal object 20. Imaging system 200 further includes an image fusion module 140a which fusion module selects valid pixels from either image sensors 130a and 130b to yield a single output image frame 150a, an image fusion module 140b which fusion module selects valid pixels from either image sensors 130a and 130b to yield a single output image frame 150b, an averaging module 240, which averaging module averages image frames 150a and 150b to yield a single output image frame 250.

In a third embodiment, the methodology of image fusion modules 140a, 140b and averaging module 240 includes the following steps: a) performing the fusion method as in the first embodiment, thereby creating an output image frame 150a; b) performing the fusion method as in the second embodiment, thereby creating an output image frame 150b; and c) averaging each pair of pixels from image frames 150a and 150b whereby setting the value of a corresponding final output pixel in image frame 250.

In variations of the present invention, image sensor arrays 130a and 130b are selected such that there are a limited number of respective pairs of pixels, where both pixels are defective. Reference is also made to Figure 3, which illustrates examples of a defective pixel 134 having immediately adjacent valid pixels 132. In such cases, at least one of image sensor arrays 130a and 130b are selected such that the mutual defective pixels 134 have no immediately adjacent defective pixel 134. For the purpose of a clear description, with no limitation, image sensor arrays 130a is taken as the image sensor array that has no immediately adjacent defective pixels 134. In such variations of the present invention, for each pair of mutual defective pixels 134, the value of a corresponding final output pixel in image frame 250 is set to be the average of the K immediately adjacent neighboring pixels 132 of the defective pixel 134, in image sensor arrays 130a. Figure 3 illustrates two examples: in one example K=4 and in the other, K=8.

In other variations of the present invention, image sensor arrays 130a and 130b are selected such that there are a limited number of respective pairs of pixels, where both pixels are partially defective. The output pixel is proportionally average from the partially defective pixels. For example, pixel P;a senses 60% of the arriving energy and pixel P,b senses 75% of the arriving energy. In such a case the output pixel Pjout is averaged as follow:

P.out = (Pja*60 + P,b*75) / 130.

Reference is also made to Figure 4, which illustrates examples beam splitter configuration for camera systems (100, 200) according to the present invention. In such variations, image acquisition devices HOa and HOb share a single front lens 170 and the incoming light is split by beam splitter 180 into two beams, where a first beam is directed towards image sensor arrays 130a and the second beam is directed towards image sensor arrays 130a.

The invention being thus described in terms of embodiments and examples, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the claims.