Compact Optic Design for Digital Image Capture Devices
A compact optic design is disclosed in which an image capture device's cover glass (or other transparent material) is imbued with optic power and affixed directly to the device's housing. A lens barrel, in which one or more additional lens elements are mounted, may be aligned with the optical lens formed by the cover glass and an image sensor to provide a complete camera module.
This disclosure relates generally to the field of optics. More particularly, this disclosure relates to a novel and highly beneficial techniques for fashioning an optical stack or camera module.
Camera modules for mobile telephone and other small form-factor electronic devices are one of the key components in controlling device thickness. Referring to
Thickness 145 of camera module 100 is controlled by several factors, a primary consideration among which is the module's overall optical track 150, defined as the distance from the camera's optical sensor surface 140 to the outer surface or top of its first lens element 120. This latter distance is fixed by the limits of Maxwell's equations (for a given sensor and pixel size). It would be beneficial to provide a means to reduce the overall camera height or thickness 145 so as to permit the design of thinner products, resulting in lower mass and improved product aesthetics.
SUMMARYIn one embodiment the inventive concept provides a compact optic design for use in electronic devices. The disclosed design permits the design and manufacture of digital image capture devices that are thinner and/or lighter than comparable prior art devices. One particular embodiment provides an image capture system that includes a first lens member fixed to and flush with an external surface of an electronic device (e.g., a mobile telephone, a personal music player, a personal digital assistant, and various forms of computer systems including desktop, laptop and tablet computer systems). A lens assembly that includes or more additional lens elements (each of which are in fixed relationship to one another) is axially aligned with, and in a movable relationship to, the first lens element. In one embodiment, the lens assembly may be a lens or lens barrel. A light sensor may then be positioned so that light passing through the axially aligned lenses (i.e., the first lens and the one or more additional lens elements mounted in the lens assembly) is focused on light collecting sites of the sensor. Illustrative light sensors include, but are not limited to, charge-coupled device (3D) and complementary metal-oxide-semiconductor (CMOS) active pixel sensors.
In another embodiment, an infrared cutoff filter (IRCF) element may be positioned between the bottom of the lens assembly (i.e., the side away from the first lens element) and the light sensor. In still another embodiment, an aperture stop may be fixed to a surface of a lens in the lens assembly that is closest to the first lens element. In yet another embodiment, a mechanical stop may be added to a surface of the lens assembly and/or the backside of the device's external surface (i.e., the same surface to which the first lens is flush). The mechanical stop providing a mechanism to prevent any lens in the lens assembly from physically contacting the first lens.
This disclosure pertains to systems and methods to reduce the height, size or thickness of an image capture device. In general, techniques are disclosed for fashioning a camera module that is more compact than that available in the prior art. More particularly, an compact optic design is disclosed wherein a device's cover glass (or other transparent material) is imbued with optic power and affixed directly to the device's housing. A lens barrel, in which one or more additional lens elements can be mounted, may be optically aligned with the lens/cover glass and an image sensor to provide a complete camera module. As used herein, a “lens” is an optical element that has a finite focal length. At present, the disclosed embodiments can provide a 10%-15% reduction in the camera module's overall height and system thickness in comparison to conventional designs having similar optic capabilities (e.g., number of lens elements).
In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the inventive concept. As part of this description, some of this disclosure's drawings represent structures and devices in block diagram form in order to avoid obscuring the invention. In the interest of clarity, not all features of an actual implementation are described in this specification. Moreover, the language used in this disclosure has been principally selected for readability and instructional purposes, and may not have been selected to delineate or circumscribe the inventive subject matter, resort to the claims being necessary to determine such inventive subject matter. Reference in this disclosure to “one embodiment” or to “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention, and multiple references to “one embodiment” or “an embodiment” should not be understood as necessarily all referring to the same embodiment.
It will be appreciated that in the development of any actual implementation (as in any development project), numerous decisions must be made to achieve the developers' specific goals (e.g., compliance with system- and business-related constraints), and that these goals may vary from one implementation to another. It will also be appreciated that such development efforts might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the design and implementation of camera or optic systems having the benefit of this disclosure. Further, the application in which the disclosed embodiments are described is a mobile telephone. No such limitation is inherent in the described technology. By way of example only, a camera module in accordance with this disclosure could also be implemented in any small form-factor digital device incorporating image capture capability. By way of example, stand-alone digital cameras, portable music players, personal digital assistants, laptop/notebook computer systems, and tablet computer systems.
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Together, lens L1 305 and lens barrel 310 (housing lenses L2 315-L5 330) form a 5-lens stack having an overall optical track 335 and device thickness 340. Incorporating lens L1 305 into the device's back-plate in accordance with this disclosure allows the lens barrel to be thinner (it now only has to host four lenses rather than 5 as in a prior art 5-lens camera module). This, in turn, permits the module's overall thickness 340 to be less than that of a prior art 5-lens module. The same may be said for all comparable devices. That is, a device in accordance with
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In one embodiment, a support structure may be insert-molded with the lens element that is coincident with a device's external surface (e.g., lens L1 305). An advantage of this approach is that a low compliance joint is created ensuring minimal displacement of the lens toward the device's interior (i.e., toward lens L2 315) under external loading. In another embodiment, the first lens element (i.e., lens L1 305) may be affixed into a support structure using pressure-sensitive adhesive or epoxy. In both embodiments, the support structure itself may, for example, be molded plastic or machined alloy.
Because lens member L1 305 is mechanically separated from the lenses mounted in lens barrel 310, it may be beneficial during assembly operations to ensure these lenses are properly aligned. In one embodiment, lens alignment may be achieved using an active alignment process. During active alignment, image sensor 250 is activated and the position of first lens member L1 305 is moved in the x, y and z directions until a suitable position is achieved (e.g., an acceptable position along the lens assemblies “through-focus curve” is found).
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Processor 605 may execute instructions necessary to carry out or control the operation of many functions performed by device 600. Processor 605 may, for instance, drive display 610 and receive user input from user interface 615. User interface 615 can take a variety of forms, such as a button, keypad, dial, a click wheel, keyboard, display screen and/or a touch screen. Processor 605 may be a system-on-chip such as those found in mobile devices and include a dedicated graphics processing unit (GPU). Processor 605 may be based on reduced instruction-set computer (RISC) or complex instruction-set computer (CISC) architectures or any other suitable architecture and may include one or more processing cores. Graphics hardware 620 may be special purpose computational hardware for processing graphics and/or assisting processor 605 process graphics information. In one embodiment, graphics hardware 620 may include a programmable graphics processing unit (GPU).
Sensor and camera circuitry 650 may utilize the compact optic design disclosed herein to capture still and video images. Output from camera circuitry 650 may be processed, at least in part, by video codec(s) 655 and/or processor 605 and/or graphics hardware 620, and/or a dedicated image processing unit incorporated within circuitry 650. Images so captured may be stored in memory 660 and/or storage 665. Memory 660 may include one or more different types of media used by processor 605, graphics hardware 620, and image capture circuitry 650 to perform device functions. For example, memory 660 may include memory cache, read-only memory (ROM), and/or random access memory (RAM). Storage 665 may store media (e.g., audio, image and video files), computer program instructions or software, preference information, device profile information, and any other suitable data. Storage 665 may include one more non-transitory storage mediums including, for example, magnetic disks (fixed, floppy, and removable) and tape, optical media such as CD-ROMs and digital video disks (DVDs), and semiconductor memory devices such as Electrically Programmable Read-Only Memory (EPROM), and Electrically Erasable Programmable Read-Only Memory (EEPROM). Memory 660 and storage 665 may be used to retain computer program instructions or code organized into one or more modules and written in any desired computer programming language. When executed by, for example, processor 605 such computer program code may implement one or more of the methods described herein.
It is to be understood that the above description is intended to be illustrative, and not restrictive. The material has been presented to enable any person skilled in the art to make and use the invention as claimed and is provided in the context of particular embodiments, variations of which will be readily apparent to those skilled in the art (e.g., some of the disclosed embodiments may be used in combination with each other). By way of example, camera modules in accordance with this disclosure are not limited to rear-facing camera modules or modules utilizing a 5-lens assembly as illustrated in
Claims
1. An image capture system, comprising:
- an electronic device having an outer surface;
- a first lens member that is a part of the outer surface of the electronic device;
- one or more additional lens members in fixed relation to each other and in movable relation with the first lens member, wherein each of the first lens member and the outer surface is stationary in relation to each of the one or more additional lens members; and
- a sensor having light sensitive elements on a first surface, wherein the one or more additional lens members are positioned between the first surface of the sensor and the first lens member.
2. The image capture system of claim 1, wherein the one or more additional lens members are mounted in a lens barrel.
3. The image capture system of claim 2, further comprising an infrared cutoff filter (IRCF) juxtaposed between the lens barrel and the sensor.
4. The image capture system of claim 1, wherein the first lens member has a focal length that is greater than an aggregate focal length of the one or more additional lens members.
5. The image capture system of claim 1, wherein the first lens member does not have an aperture stop coincident with, or coupled to, any surface of the first lens member.
6. The image capture system of claim 5, wherein the aperture stop is fixedly attached to an object side surface of a second lens member, the second lens member being one of the one or more additional lens members.
7. The image capture system of claim 6, wherein the object side surface is closest to, and oriented toward, the first lens member.
8. The image capture system of claim 1, wherein the one or more additional lens members, the first surface, and the outer surface of the electronic device are substantially parallel.
9. The image capture system of claim 1, wherein the first lens member comprises a support structure into which the first lens member has been insert-molded.
10. The image capture system of claim 1, further comprising a mechanical element configured to prevent any one of the one or more additional lens members from physically contacting the first lens member.
11. The image capture system of claim 10, wherein the one or more additional lens members are mounted in a lens barrel, the lens barrel having a top surface, the top surface of the lens barrel being oriented toward the first lens member, and wherein the mechanical element is affixed to the top surface of the lens barrel.
12. The image capture system of claim 1, comprising one of a mobile telephone, a tablet computer system, a notebook computer system, a personal music player, and a desktop computer system.
13. The image capture system of claim 1, wherein the outer surface of the electronic device is flush with at least a portion of the first lens member.
14. An image capture system, comprising:
- an electronic device having an outer surface;
- a first lens member having a first surface that is a part of the outer surface of the electronic device;
- a second lens member mounted in a lens assembly, wherein the lens assembly is in movable relation with the first lens member, wherein each of the first lens member and the outer surface is stationary in relation to the lens assembly;
- an aperture stop fixedly attached to an object side surface of the second lens member; and a sensor having light sensitive elements on a third surface, wherein the second lens member is positioned between the third surface and the first lens member.
15. The image capture system of claim 14, wherein the first lens member has a focal length that is greater than an aggregate focal length of the second lens member and the zero or more additional lens members housed in the lens assembly.
16. The image capture system of claim 14, wherein the outer surface of the electronic device, the second lens member, and third surface are substantially parallel.
17. The image capture system of claim 14, further comprising a mechanical stop configured to prevent any lens member mounted in the lens assembly from physically contacting the first lens member.
18. The image capture system of claim 17, wherein the mechanical stop comprises a component affixed to, or made part of, the lens assembly.
19. The image capture system of claim 14, comprising one of a mobile telephone, a tablet computer system, a notebook computer system, a personal music player, and a desktop computer system.
20. The image capture system of claim 14, wherein the outer surface of the electronic device is flush with at least a portion of the first lens member.
Type: Application
Filed: Jul 25, 2016
Publication Date: Nov 17, 2016
Inventors: Douglas S. Brodie (Los Gatos, CA), Miodrag Scepanovic (Santa Clara, CA)
Application Number: 15/218,478