HK1209551B - Compact spacer in multi-lens array module - Google Patents

Description

Compact spacers in multi-lens array modules

Technical Field

The present invention relates generally to image sensors, and more particularly to a lens array for a segmented image sensor.

Background Art

An image capture unit typically includes an image sensor and an imaging lens. The imaging lens focuses light onto the image sensor to form an image, and the image sensor converts the light into an electrical signal. The electrical signal is then output from the image capture unit to a host electronic system or other unit within a subsystem. This electronic system can be a mobile phone, computer, digital camera, or medical device.

As the use of image capture units in electronic systems increases, demands on image capture unit features, capabilities, and device size also increase. For example, there is a growing demand for image capture units with a lower profile so that the overall size of the electronic system incorporating the image capture unit can be reduced without sacrificing the quality of the captured optical image. The profile of an image capture unit can be related to the distance from the bottom of the image sensor to the top of the imaging lens.

Summary of the Invention

In an exemplary embodiment, an apparatus includes an image sensor partitioned into N image sensor regions, wherein the image sensor is attached to a circuit board; a lens array comprising N lenses disposed proximate to the image sensor, wherein each of the N lenses is arranged to focus a single image onto a respective one of the N image sensor regions; and a spacer structure stacked between the lens array and the circuit board to separate the lens array from the image sensor, wherein the spacer structure surrounds a perimeter surrounding all of the N image sensor regions and N lenses such that the spacer structure is not disposed between the N lenses and any of the N image sensor regions of the image sensor.

In another exemplary embodiment, an imaging system includes a pixel array comprising an image sensor partitioned into N image sensor regions, wherein each of the N image sensor regions has a plurality of pixels arranged therein, wherein the image sensor is attached to a circuit board; a lens array comprising N lenses disposed proximate to the image sensor, wherein each of the N lenses is arranged to focus a single image onto a respective one of the N image sensor regions; a spacer structure stacked between the lens array and a printed circuit to separate the lens array from the image sensor, wherein the spacer structure surrounds a perimeter surrounding all of the N image sensor regions and the N lenses such that the spacer structure is not disposed between the N lenses and any of the N image sensor regions of the image sensor; control circuitry coupled to the pixel array to control operation of the pixel array; and readout circuitry coupled to the pixel array to read out single image data from the plurality of pixels.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting and non-exhaustive embodiments of the present invention are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various views unless otherwise specified.

FIG. 1A is a schematic diagram of an image capture unit including an imaging lens and an image sensor.

FIG. 1B is a schematic diagram of a low-profile image capture unit including a low-profile imaging lens and an image sensor.

2 illustrates a top view of one example of an image sensor having four segmented regions in accordance with the teachings of the present invention.

3 illustrates a top view of one example of a 2×2 multi-lens array module positioned over an image sensor having four segmented regions in accordance with the teachings of the present invention.

4 is a cross-section illustrating two lenses of an example 2×2 multi-lens array module positioned over two segmented regions of an example low-profile image capture unit in accordance with the teachings of the present invention.

5 is a block diagram illustrating one example of a portion of an image sensing system including a multi-lens array module positioned over an image sensor having segmented areas in accordance with the teachings of the present invention.

Corresponding reference characters indicate corresponding components throughout the several views of the drawings. Those skilled in the art will appreciate that the elements in the figures are illustrated for simplicity and clarity and are not necessarily drawn to scale. For example, to help improve understanding of the various embodiments of the present invention, the dimensions of some of the elements in the figures may be exaggerated relative to other elements. Furthermore, common and well-known elements that are useful or necessary in commercially feasible embodiments are generally not depicted to facilitate a less obstructed view of the various embodiments of the present invention.

DETAILED DESCRIPTION

In the following description, numerous specific details are set forth to provide a thorough understanding of the present invention. However, it will be apparent to one of ordinary skill in the art that it is not necessary to employ specific details to practice the present invention. In other instances, well-known materials or methods are not described in detail to avoid obscuring the present invention.

References throughout this specification to "one embodiment," "an embodiment," "an example," or "an instance" mean that a particular feature, structure, or characteristic described in connection with the embodiment or instance is included in at least one embodiment of the present invention. Thus, the appearances of the phrases "in one embodiment," "in an embodiment," "an example," or "an instance" in various places throughout this specification are not necessarily all referring to the same embodiment or instance. Furthermore, in one or more embodiments or instances, the particular features, structures, or characteristics may be combined in any suitable combinations and/or subcombinations. The particular features, structures, or characteristics may be included in an integrated circuit, an electronic circuit, a combinational logic circuit, or other suitable components that provide the described functionality. In addition, it should be understood that the figures provided herein are for explanation purposes to persons of ordinary skill in the art and that the figures are not necessarily drawn to scale.

The present disclosure is directed to example methods and apparatus for a multi-lens array module including a compact spacer structure for use in a low-profile image capture unit. As will be appreciated, a multi-lens array module for use in a low-profile image capture unit can be provided in accordance with the teachings of the present disclosure without sacrificing the quality of the captured optical image, such as resolution (i.e., number of pixels) and clarity, to achieve a low profile in accordance with the teachings of the present disclosure.

For illustration, FIG1A is a schematic diagram of an image capture unit 100 including an imaging lens 102 and an image sensor 104. The distance between lens 102 and image sensor 104 is approximately f, where f is the focal length of lens 102. The width of image sensor 104 covered by lens 102 is W, and the lens diameter is D. For comparison, FIG1B shows a schematic diagram of a low-profile image capture unit 106 including an imaging lens 108 and an image sensor 110. The distance between lens 108 and image sensor 110 is approximately f/2, where f/2 is the focal length of lens 108. The width of image sensor 110 covered by lens 108 is W/2, and the lens diameter is D/2.

In the low-profile image capture unit, the imaging lens is replaced with a low-profile imaging lens, while the image sensor remains unchanged. Image sensors 104 and 110 are identical, and both image sensors have the same pixel array structure. Because the width of image sensor 110 is half the width of image sensor 104, image sensor 110 will have half the number of pixels as image sensor 104 in one dimension. In both dimensions, image sensor 110 will have one-quarter the number of pixels as image sensor 104. In other words, the number of pixels in the captured image is roughly proportional to the square of the distance between the lens and the image sensor.

FIG2 illustrates an image sensor 212 having four segmented regions 214, 216, 218, and 220 arranged in close proximity to one another on a circuit board 221 in accordance with the teachings of the present invention. As will be discussed in greater detail below, in accordance with the teachings of the present invention, each segmented region 214, 216, 218, and 220 is covered by a corresponding imaging lens in a multi-lens array module. In this manner, the focal length of each imaging lens in the multi-lens array module can be half that of an imaging lens when the image sensor is not segmented into four regions. Thus, in accordance with the teachings of the present invention, a low-profile image capture unit can be constructed using four lenses and four segmented regions of the image sensor. The low-profile image capture unit will have approximately the same resolution (i.e., the same number of pixels) as the original image capture unit because four regions of the image sensor are used. The area of each segmented region can be similar to that of the image sensor 110 of FIG1B. In one example, segmented regions 214 , 216 , 218 , and 220 of image sensor 212 are designated as red (R), green (G), blue (B), and transparent (C) regions, respectively.

FIG3 illustrates a top view of one example of a 2×2 multi-lens array module 311 positioned above an image sensor having four segmented regions mounted on a circuit board 321 in accordance with the teachings of the present invention. In one example, it should be understood that the image sensor having four segmented regions mounted on the circuit board 321 of FIG3 is one example of the image sensor 212 having four segmented regions 214, 216, 218, 220 mounted on the circuit board 221 discussed above with respect to FIG2. Therefore, it should be understood that similarly named and numbered elements mentioned below are coupled and function as described above.

3 , in accordance with the teachings of the present invention, multi-lens array module 311 includes a 2×2 lens array 313 including lenses 322, 324, 326, and 328 mounted to a spacer structure 330 above an image sensor having four segmented regions mounted on a circuit board 321. In one example, in accordance with the teachings of the present invention, lenses 322, 324, 326, and 328 of lens array 313 are low-profile lenses mounted to a glass wafer 315 attached to a spacer structure 330, which is stacked between lens array 313 and circuit board 321. In one example, spacer structure 330 is adapted to separate lens array 313 from the image sensor by the focal length of lenses 322, 324, 326, and 328. As shown in the illustrated example, in accordance with the teachings of the present invention, spacer structure 330 surrounds the perimeter of all of the segmented regions of the image sensor and lenses 322, 324, 326, and 328, such that spacer structure 330 is not disposed between lenses 322, 324, 326, and 328 and any of the segmented regions of the image sensor mounted on circuit board 321. In one example, spacer structure 330 is bonded directly to circuit board 321 in accordance with the teachings of the present invention.

As shown in the depicted example, lenses 322, 324, 326, and 328 are designated as red (R), green (G), blue (B), and transparent (C) regions, respectively. In other words, each of lenses 322, 324, 326, and 328 is arranged to focus a single image onto a respective one of the red (R), green (G), blue (B), and transparent (C) regions of the image sensor area (e.g., segmented regions 214, 216, 218, and 220, respectively, of image sensor 212, as illustrated in FIG. 2 ). Thus, in one example, lens 322 forms only a red image, lens 324 forms only a green image, and lens 326 forms only a blue image. Additionally, in one example, each of lenses 322, 324, 326, and 328 has a different respective radius of curvature corresponding to the particular color of light being focused onto the corresponding image sensor area, in accordance with the teachings of the present invention.

In contrast, a typical image capture unit uses a single imaging lens that simultaneously forms red, green, and blue images. However, since each lens 322, 324, 326, and 328 forms a single color image according to the teachings of the present invention, the optical quality (e.g., clarity) of each individual image can be improved by individually adjusting the radius of curvature of each lens and the corresponding image sensor. Thus, in one example, according to the teachings of the present invention, the radius of curvature of each of lenses 322, 324, 326, and 328 and the corresponding segmented image sensor can be individually adjusted according to the wavelength of light to obtain high-quality images. Thus, in one example, according to the teachings of the present invention, the radius of curvature of the red lens relative to the red region of the image sensor, the radius of curvature of the green lens relative to the green region of the image sensor, and the radius of curvature of the blue lens relative to the blue region of the image sensor are different. In one example, the radius of curvature of the C lens relative to the C region of the image sensor can be adjusted to correspond to white light, or, for example, can be adjusted to correspond to green light.

FIG4 illustrates a cross-section of two lenses 422 and 424 of lens array 413 of an example 2×2 multi-lens array module 411 positioned above two segmented regions 414 and 416 of an image sensor 412 of one example of a low-profile image capture unit in accordance with the teachings of the present invention. In one example, the cross-section illustrated in FIG4 may correspond to dashed line AA′ of FIG2 and/or dashed line AA′ of FIG3 . Segmented regions 414 and 416 of image sensor 412 of FIG4 may be examples of regions 214 and 216 of image sensor 212 of FIG2 . Similarly, lenses 422 and 424 and spacer structure 430A of lens array 413 of FIG4 may be examples of lenses 322 and 324 and spacer structure 330, respectively, of lens array 313 of FIG3 . Thus, it should be understood that similarly named and numbered elements mentioned below couple and function as described above.

4 , spacer structure 430A is adapted to separate lenses 422 and 424 of lens array 413 from segmented regions 414 and 416 of image sensor 412 by a focal length f of lenses 422 and 424. In one example, the focal length f of lenses 422 and 424 and the width W of segmented regions 414 and 416 of image sensor 412 are half the focal length of lens 102 and half the width W of image sensor 104 of FIG. 1A .

A typical image capture unit may include a Bayer-type color filter array on the image sensor. In contrast, the segmented regions of image sensors 414 and 416 of FIG. 4 may not include a Bayer-type color filter array. Referring back to the example described above in FIG. 2 , segmented regions 214, 216, 218, and 220 may be designated as red (R), green (G), blue (B), and clear (C) regions, respectively. Thus, the red region may be covered by a single red filter, the green region by a single green filter, the blue region by a single blue filter, and the clear or C region by any filter, a single clear filter, or a single green filter.

As shown in the example depicted in FIG4 , the radius of curvature of lens 422 is different from the radius of curvature of lens 424. In one example, the radius of curvature of lens 422, having a focal length f, corresponds to light having a first color, such as, but not limited to, red (R), and the radius of curvature of lens 424, having a focal length f, corresponds to light having a second color, such as, but not limited to, green (G). Thus, in accordance with the teachings of the present invention, a single image having the first color is focused by lens 422 onto partitioned area 414 of image sensor 412, and the same single image having the second color is focused by lens 424 onto partition 416 of image sensor 412.

In one example, a single color filter may be disposed over each lens. Alternatively, a single color filter may be disposed between each lens and each segmented region of a single image sensor. For example, as shown in the example depicted in FIG4 , color filters 432 and 434 are disposed over lenses 422 and 424, respectively. Continuing with the example discussed above in which the radius of curvature of lens 422 corresponds to red (R) light and the radius of curvature of lens 424 corresponds to green (G) light, filter 432 is a red (R) filter and filter 434 is a green (G) filter.

Referring briefly back to the example depicted in FIG2 , the red (R) region includes only red pixels, the green (G) region includes only green pixels, and the blue (B) region includes only blue pixels. The transparent or C region may include white pixels when no filter is applied and green pixels when a green filter is applied. A readout system and/or processor (not shown) may rearrange the red, green, and blue pixels into a Bayer pattern or any pattern for further processing the color signal and forming a color image. In accordance with the teachings of the present invention, the C pixels may be used as white pixels for specific processing or as green pixels only.

Referring back to the example of multi-lens array module 411 depicted in FIG4 , lenses 422 and 424 of lens array 413 are low-profile lenses mounted to a glass wafer 415 attached to a spacer structure 430A, which is stacked between lens array 413 and circuit board 421. In one example, spacer structure 430A is adapted to separate lens array 413 from image sensor 412 by a focal length f of lenses 422 and 424 in accordance with the teachings of the present invention. In one example, multi-lens array module 411 may also include lenses 417 and 419 mounted to a glass wafer 417, which is attached to spacer structures 430A and 430B, as shown. In one example, spacer structures 430A and 430B are substantially similar and stacked as shown. Indeed, as shown in the illustrated example, in accordance with the teachings of the present invention, spacer structures 430A and 430B surround the perimeter of all of the segmented regions surrounding the image sensor and lenses 422, 424, 417, and 419, such that neither spacer structures 430A nor spacer structures 430B are disposed between lenses 422, 424, 417, and 419 and/or any of the segmented regions 414 and 416 of image sensor 412 mounted on circuit board 421. In one example, in accordance with the teachings of the present invention, spacer structures 430A and 430B are bonded directly onto circuit board 421 as shown.

FIG5 is a block diagram illustrating one example of a portion of an image sensing system 536 including a multi-lens array module 511 positioned above an image sensor 512 having segmented regions 514, 516, 518, and 520 in accordance with the teachings of the present invention. In one example, it should be understood that the example multi-lens array module 511 of FIG5 is one example of the multi-lens array module 311 of FIG3 or the multi-lens array module 411 of FIG4, or that the example image sensor 512 of FIG5 is one example of the image sensor 212 of FIG2 or the image sensor 412 of FIG4. Thus, it should be understood that similarly named and numbered elements mentioned below are coupled and function as described above.

As shown in the example depicted in FIG5 , imaging system 536 includes a multi-lens array module 511 positioned above image sensor 512, readout circuitry 540, function logic 542, and control circuitry 544. In the illustrated example, image sensor 512 is segmented into four segmented regions 514, 516, 518, and 520. In one example, each segmented region 514, 516, 518, and 520 is covered by a color filter. In one example, in accordance with the teachings of the present invention, multi-lens array module 511 includes a spacer structure, such as spacer structure 330 of FIG3 or spacer structures 430A and 430B of FIG4 , stacked between the lens arrays of multi-lens array module 511 and image sensor 512. As shown in the depicted example, multi-lens array module 511 is adapted to direct a single image 538 onto image sensor 512. In one example, each lens in the lens array included in multi-lens array module 511 is adapted to direct a single image 538 onto a respective one of partitions 514 , 516 , 518 , and 520 , respectively, as discussed above, in accordance with the teachings of the present invention.

As shown in the depicted example, image sensor 512 includes a two-dimensional (2D) array of pixel cells (e.g., pixels P1, P2, ... Pn). Each pixel cell in the pixel array can include a CMOS pixel or a CCD pixel. As illustrated, each pixel cell is arranged into a row (e.g., rows R1 through Ry) and a column (e.g., columns C1 through Cx) of the pixel array to acquire image data of a person, place, object, etc., which can then be used to reproduce a 2D image of the person, place, object, etc. In one example, image sensor 512 is a backside illuminated (BSI) image sensor. In one example, image sensor 512 is a frontside illuminated (FSI) image sensor.

After each pixel cell P1, P2, ... Pn has acquired its image data or image charge, the image data is read out from the image sensor 512 via the bit lines to the readout circuitry 540, which can then be transferred to the function logic 542. The readout circuitry 540 may include amplification circuitry, analog-to-digital (ADC) conversion circuitry, or other circuitry. The function logic 542 may simply store the image data or even manipulate the image data by applying post-image effects (e.g., cropping, rotation, red-eye removal, brightness adjustment, contrast adjustment, or other). In one example, the readout circuitry 540 may read out the image data from the image sensor 512 one row at a time along the readout column lines, or read out the image data from each partition 514, 516, 518, and 520 (illustrated), or may read out the image data using a variety of other techniques (not illustrated), such as serial readout or simultaneous full parallel readout of all pixels.

Control circuitry 544 is coupled to image sensor 512 to control the operating characteristics of pixel array 512. For example, control circuitry 544 may generate a shutter signal for controlling image acquisition. In one example, the shutter signal is a global shutter signal for simultaneously enabling all pixels within image sensor 512 to simultaneously capture their respective image data during a single acquisition window. In an alternative example, the shutter signal is a rolling shutter signal, whereby each pixel row, column, group, or partition is sequentially enabled during successive acquisition windows.

It should be understood that the low-profile image capture unit is not limited to a 2×2 lens array; any size of lens array in the multi-lens array module 511 is possible. Therefore, the image sensor 512 is not limited to four segmented regions. Any number of segmented regions is possible. The segmented regions 514, 516, 518, and 520 of the image sensor 512 can be square or rectangular.

The above description of the illustrated examples of the present invention, including what is described in the Abstract, is not intended to be exhaustive or limited to the precise forms disclosed. Although specific embodiments and examples of the invention are described herein for illustrative purposes, various equivalent modifications may be made without departing from the broader spirit and scope of the invention.

These modifications may be made to examples of the present invention in light of the above detailed description. The terms used in the appended claims should not be construed to limit the invention to the specific embodiments disclosed in the specification and claims. Rather, the scope is to be determined entirely by the appended claims, which are to be construed in accordance with established doctrines of claim interpretation. Accordingly, the specification and drawings are to be regarded as illustrative rather than restrictive.

Claims (18)

1. An imaging device comprising: An image sensor is divided into multiple image sensor areas, wherein the image sensor is attached to a circuit board, and the circuit board and the image sensor are non-integrated components; A lens array comprising multiple lenses, positioned close to the image sensor, wherein each of the multiple lenses is arranged to focus a single image onto a corresponding one of the multiple image sensor regions; and A spacer structure extending between the lens array and the circuit board to separate the lens array from the image sensor, wherein the spacer structure is directly coupled to the circuit board and surrounds the perimeter of all the plurality of image sensor areas and the plurality of lenses, such that the spacer structure is not positioned between any of the plurality of lenses and any of the plurality of image sensor areas of the image sensor. 2. The imaging device according to claim 1, wherein the spacer structure is adapted to separate the lens array from the image sensor by the focal length of the plurality of lenses. 3. The imaging device of claim 1, wherein the plurality of lenses comprises: a first lens having a first radius of curvature and positioned at a first focal length away from a corresponding one of the plurality of image sensor areas; a second lens having a second radius of curvature and positioned at a second focal length away from a corresponding one of the plurality of image sensor areas; and a third lens having a third radius of curvature and positioned at a third focal length away from a corresponding one of the plurality of image sensor areas, wherein the first, second, and third radii of curvature are different. 4. The imaging device according to claim 3, wherein the first radius of curvature corresponds to light having a first color, wherein the second radius of curvature corresponds to light having a second color, and wherein the third radius of curvature corresponds to light having a third color. 5. The imaging device of claim 4, wherein the first lens focuses the single image having the first color onto a corresponding one of the plurality of image sensor areas, wherein the second lens focuses the single image having the second color onto a corresponding one of the plurality of image sensor areas, and wherein the third lens focuses the single image having the third color onto a corresponding one of the plurality of image sensor areas. 6. The imaging device according to claim 4, further comprising first, second, and third color filters respectively close to the first, second, and third lenses. 7. The imaging apparatus of claim 1, wherein the plurality of lenses further comprises a fourth lens having a fourth radius of curvature and positioned at a fourth focal length away from the respective one of the plurality of image sensor regions. 8. The imaging device according to claim 7, wherein the fourth focal length corresponds to white light. 9. The imaging device according to claim 7, wherein the fourth focal length corresponds to green light. 10. An imaging system comprising: A pixel array comprising an image sensor divided into multiple image sensor regions, each of the multiple image sensor regions having multiple pixels arranged therein, wherein the image sensor is attached to a circuit board, and the circuit board and the image sensor are non-integrated components. A lens array comprising a plurality of lenses is positioned close to the image sensor, wherein each of the plurality of lenses is arranged to focus a single image onto a corresponding one of the plurality of image sensor regions. A spacer structure extending between the lens array and the circuit board to separate the lens array from the image sensor, wherein the spacer structure is directly coupled to the circuit board and surrounds the perimeter of all the plurality of image sensor areas and the plurality of lenses, such that the spacer structure is not positioned between any of the plurality of lenses and any of the plurality of image sensor areas of the image sensor. Control circuitry coupled to the pixel array to control the operation of the pixel array; and A readout circuit is coupled to the pixel array to read out individual image data from the plurality of pixels. 11. The imaging system of claim 10, further comprising functional logic coupled to the readout circuitry to store the individual image data read from each of the plurality of image sensor regions. 12. The imaging system of claim 10, wherein the spacer structure is adapted to separate the lens array from the image sensor by the focal length of the plurality of lenses. 13. The imaging system of claim 10, wherein the plurality of lenses comprises: a first lens having a first radius of curvature and positioned at a first focal length away from a corresponding one of the plurality of image sensor regions; a second lens having a second radius of curvature and positioned at a second focal length away from a corresponding one of the plurality of image sensor regions; and a third lens having a third radius of curvature and positioned at a third focal length away from a corresponding one of the plurality of image sensor regions, wherein the first, second, and third radii of curvature are different. 14. The imaging system of claim 13, wherein the first radius of curvature corresponds to light having a first color, wherein the second radius of curvature corresponds to light having a second color, and wherein the third radius of curvature corresponds to light having a third color. 15. The imaging system of claim 14, wherein the first lens focuses the single image having the first color onto a corresponding one of the plurality of image sensor areas, wherein the second lens focuses the single image having the second color onto a corresponding one of the plurality of image sensor areas, and wherein the third lens focuses the single image having the third color onto a corresponding one of the plurality of image sensor areas. 16. The imaging system of claim 14, further comprising first, second, and third color filters respectively close to the first, second, and third lenses. 17. The imaging system of claim 10, wherein the plurality of lenses further comprises a fourth lens having a fourth radius of curvature and positioned at a fourth focal length away from the respective one of the plurality of image sensor regions. 18. The imaging system of claim 17, wherein the fourth focal length corresponds to white light.