Compact Camera Module Research Articles

Real-time segmentation network for compact camera module assembly adhesives based on improved U-Net

Real-time segmentation network for compact camera module assembly adhesives based on improved U-Net

A K-Means Clustering and the Prim’s Minimum Spanning Tree-Based Optimal Picking-List Consolidation and Assignment Methodology for Achieving the Sustainable Warehouse Operations

Rapid industrialization has caused the concentration of greenhouse gases in the atmosphere to increase rapidly, leading to drastic global climate changes and ecological degradation. To establish a sustainable supply chain for consumer electronic products, this study focuses on warehouse operations and develops a K-means clustering and Prim’s minimum spanning tree-based optimal picking-list consolidation and assignment methodology. Compact camera modules are used to demonstrate and verify the effectiveness of this methodology. This methodology can be divided into two parts. First, the K-means clustering method is applied to conduct a picking-list consolidation analysis to create an optimal picking-list consolidation strategy for sustainable warehouse operations. Second, the most similar picking lists in each cluster are connected using Prim’s minimum spanning tree algorithm to generate the connected graph with the minimum spanning tree so as to establish a picking-list assignment strategy for sustainable warehouse operations. In this case study, this to-be model substantially reduced the traveling distance of the electric order-picking trucks within a warehouse and increased the picking efficiency to diminish the carbon emissions toward a sustainable supply chain.

Tiny Piezoelectric Multi-Layered Actuators with Application in a Compact Camera Module-Design, Fabrication, Assembling and Testing Issues.

Piezoelectric actuators with multi-layer structures have largely gained attention from academic and industry experts. This is due to its distinctive advantages of fast response time, huge generative force and the inherent good planar electromechanical coupling factor, as well as other mechanical qualities. Typically, lead zirconate titanate (PZT) is one of the most represented piezoelectric ceramic materials that have been used for multi-layer piezoelectric actuators. Piezoelectric multi-layered actuators (PMLAs) were developed vigorously in the past decades due to the emergence of portable devices, such as smartphones with a highly compact camera module (CCM) and an image stabilizer (IS). This study reviewed the progress made in the field of PMLA applications, with a particular focus on the miniaturized dimensions and associated generated output force, speed and maximum output power requirement for various loads. Several commercial attempts, such as Helimorph, Lobster and the two-degrees-of-freedom ultrasonic motor (USM), were investigated. The proposed simple bimorph and multi-layer bimorph USMs experimentally showed thrust as high as 3.08 N and 2.57 N with good free speed and structural thicknesses of 0.7 and 0.6 mm, respectively. When compared with the other 14 reported linear USMs, they ranked as the top 1 and 2 in terms of the thrust-to-volume ratio. The proposed design shows great potential for cellphone camera module application, especially in moving sensor image stabilization. This study also provided outlooks for future developments for piezoelectric materials, configurations, fabrication and applications.

Automatic compact camera module solder joint inspection method based on machine vision

Because of the contradiction between the production requirements of compact camera modules (CCMs) to achieve high efficiency and quality and the low efficiency and poor accuracy of traditional solder joint inspection methods, an automatic inspection method of CCM solder joint based on machine vision is proposed. After optimizing the imaging parameters according to the CCM inspection process, the region of interest is dynamically identified based on feature matching and image enhancement methods to remove background interference. On this basis, an improved adaptive particle swarm optimization is used to optimize the kernel extreme learning machine to automatically classify the solder joint defects. Experimental results showed that with its low latency, high precision and robustness, the CCM surface solder joint defect detection and classification method based on machine vision can effectively solve the problem of low efficiency and high cost of the current CCM solder joint defect detection technology.

쿼드 트리 분해를 이용한 딥러닝 기반의 소형 카메라 모듈 덮개 결함 분류

Compact camera modules are used in many small electronic devices. Defect detection is essential because the cover protecting the module is exposed to the environment outside. It also defects classification to provide feedback to the production process and prevent further defects from occurring. Since the size of the defect is small compared to the size of the module, we adopted the method of extracting the inspection patch. To reduce the inspection time, we employed the compact camera module defect classification system using quadtree decomposition. The module area was detected using template matching, and the unnecessary background was deleted through bit operation. By binarizing the detected module areas, defect candidates were found through quadtree decomposition. The defects were then classified through deep learning. Compared to the previously proposed patch-based method, the inspection time could be reduced.

Compact optical zoom camera module based on Alvarez elements

A compact optical zoom camera module with Alvarez freeform elements is reported. A 3 × magnification in the optical zoom system was achieved by means of lateral shifting two pairs of Alvarez lenses. The optical design performances, profiles of the freeform surfaces, tolerance analysis results, and Monte Carlo yield simulation for mass production of the optical zoom system are presented. The optomechanical structures of the whole camera module including the barrels, actuators, and the slide-guiding systems are also described. The Alvarez elements and aspheric lenses were fabricated by precise injection molding and the movable elements are actuated by voice coil motors with a stroke of 3 mm. A camera module was developed with a size of 25 mm (width) × 25 mm (length) × 6 mm (height). The zooming and imaging capabilities of this Alvarez zoom lens were demonstrated experimentally.

A Compact Low-Cost Camera Module with Modified Magnetic Restoring Force

AbstractIn recent years, compact camera modules (CCMs) have been widely used in consumer electrical and electronic products. CCMs with low cost specially are necessary for portable devices. Therefore, the present group recently developed a miniaturized open-loop controlled camera module with low cost for cellphone applications, in which the Lorentz force is balanced by a magnetic restoring force. To enhance the performance of the camera module, this article reports a pattern structure to modify the linearity of the magnetic restoring force. We fabricated a CCM prototype with the dimensions of 8.5 mm × 8.5 mm × 5 mm and demonstrated the usefulness of the pattern structure with the CCM prototype. Its potential applications are foreseeable in portable devices, such as cellphones, web cameras, personal digital assistants and other commercial electronics.

Fabrication of microoptical freeform arrays on wafer level for imaging applications.

Miniaturized imaging systems combining an ultra-compact form factor in combination with the ability of refocusing and depth imaging have gained much interest in the field of mobile imaging. Therefore, artificial compound eye cameras are an extremely promising approach for the realization of compact monolithic camera modules on wafer level. Up to now, their imaging performance was limited to low resolution in the range of VGA format according to fabrication constrains given by the established microoptical fabrication methods, namely the reflow of photoresist. In order to overcome these classical limitations, the use of refractive freeform arrays (RFFA) instead of conventional microlens arrays is inevitable. To enable high volume and cost efficient mass production of artificial compound eye cameras for mass markets like the consumer electronics industry, their fabrication on wafer level is essential, but has not been published up to now. We present a wafer level based process chain enabling the fabrication of these elements for the first time.

Scatterings

Silica Overlay Cools Solar Cells; Slow Light Could Carry Biological Cargo; A Step Toward "Molecules of Light"; Silicon Nanowire for Supercontinuum; Leaky-Wave Antenna for Wireless Telecom; An "Optical Transistor" from a Silicon Nanoparticle; Compact Camera Module Market to Double; US$81 Million for Nanotech Infrastructure; US$35 Million for Laser Defense Systems; Nanoscale Light Harvesting; Optogenetic Control of Differentiation.

A Design of Mini Actuator for Compact Camera without Using Permanent Magnet

This paper presents a design of mini actuator without using permanent magnet for auto-focus (AF) compact camera module (CCM) built on mobile phone, tablet PC and notebook. The current through the coils of electromagnets will yield magnetic force to move the moving part up and down. Comparing with conventional spring-type voice coil motor (VCM) and non-spring type VCM, the proposed actuator eliminates the concerns of rare earth supply and magnetic flux leakage which can fail the function of magnetic flux sensitive device such as e-compass. The proposed actuator also simplifies the power converter design from bipolar scheme as required by conventional non-spring type VCM to unipolar. A comprehensive electromagnetic analysis is performed by using finite element method to characterize the performance of the proposed actuator. Numerical simulations demonstrate that the magnetic flux leakage in the proposed actuator is much smaller than those by conventional design.

Optical design of camera optics for mobile phones

Abstract At present, compact camera modules are included in many mobile electronic devices such as mobile phones, personal digital assistants or tablet computers. They have various uses, from snapshots of everyday situations to capturing barcodes for product information. This paper presents an overview of the key design challenges and some typical solutions. A lens design for a mobile phone camera is compared to a downscaled 35 mm format lens to demonstrate the main differences in optical design. Particular attention is given to scaling effects.

Compact camera module testing equipment with a conversion lens

Modified testing equipment for adjusting the back focal length of a compact camera module (CCM) is proposed. The advantages of this modified testing equipment which includes a conversion lens are that it saves on testing space, offers a smaller sized testing chart, as well as high speed chart changing, and variable object distances. The modified testing equipment can produce a test chart of 38.32 mm compared to an equivalent testing chart of 5000 mm with the conventional testing equipment. At the regular object distance of 2000 mm, both total track and testing chart size for the modified test equipment were 8.3% that of the conventional testing equipment. By using this testing equipment, the testing space can be shrunk significantly.

Investigation of high resolution compact gamma camera module based on a continuous scintillation crystal using a novel charge division readout method

The objective of this study is to investigate a high performance and lower cost compact gamma camera module for a multi-head small animal SPECT system. A compact camera module was developed using a thin Lutetium Oxyorthosilicate (LSO) scintillation crystal slice coupled to a Hamamatsu H8500 position sensitive photomultiplier tube (PSPMT). A two-stage charge division readout board based on a novel sub-tractive resistive readout with a truncated center-of-gravity (TCOG) positioning method was developed for the camera. The performance of the camera was evaluated using a flood 99mTc source with a four-quadrant bar-mask phantom. The preliminary experimental results show that the image shrinkage problem associated with the conventional resistive readout can be effectively overcome by the novel subtractive resistive readout with an appropriate fraction subtraction factor. The response output area (ROA) of the camera shown in the flood image was improved up to 34%, and an intrinsic spatial resolution better than 2 mm of detector was achieved. In conclusion, the utilization of a continuous scintillation crystal and a flat-panel PSPMT equipped with a novel subtractive resistive readout is a feasible approach for developing a high performance and lower cost compact gamma camera.

An automatic optical inspection system for inspection of CMOS compact camera module assembly

This paper presents the development of an automatic inspection system to check lens focus status and white balance level and to inspect defects including black and white defect, dim defect, color defect, and line defects in manufacturing process of compact camera module. To check the imaging status and inspect the defects of compact camera module, a unique image capturing system is developed to get image data from CMOS sensor at high speed. It has a complex programmable logic device, and the camera link and the frame grabber is used to transfer and store images to PC. Several kinds of unique image charts are designed to inspect the various types of defects in compact camera module, and they are implemented and displayed on the LCD monitor directly to reduce handling and exchanging time of inspection charts during test procedures. Various image processing algorithms are developed to analyze the captured image from each test chart and to find and verify the defects of camera modules. The experimental results show that the proposed system is able to reliably inspect various types of defects with high precision and high speed in real manufacturing condition.

Electroactive Polymer Actuator for Lens-Drive Unit in Auto-Focus Compact Camera Module

We propose a lens-drive unit composed of an ionic polymer-metal composite (IPMC) for an auto-focus compact camera module in cellular phones to solve the power consumption problem of voice coil motors which are widely used in commercial products. In this research, an IPMC incorporated into a lens-drive unit is designed to implement a large displacement in low-power consumption by using an anisotropic plasma treatment. Experimental results show that a camera module containing IPMCs can control and maintain the position of the lens by using proportional integral derivative control with a photo-reflective position sensor despite the non-linear actuation behavior of IPMCs. We demonstrate that the fabrication and commercialization of a lens actuator that has a large displacement and low power consumption using IPMCs is possible in the near future.

Improving the tolerance characteristics of small F/number compact camera module using wavefront coding

We propose a novel optical design method for small F/number (F/#) compact camera module using wavefront coding. Decreasing the F/# decreases the focus depth of the optical system, which can result in manufacturing tolerances so tight that fabrication is impossible. To obtain reasonable tolerances for easy fabrication and alignment of compact camera module, we designed the final imaging system to have a target wavefront with an extended focus depth. Because additional optical elements, such as phase plates, are not available for compact camera modules, target wavefront should be the combination of the wavefront errors of all lenses in the optical system. Wavefront-coded compact camera modules have higher tolerances and an extended focus depth, so that the images obtained from them have high resolution over a broad defocus range. Images simulated by a wavefront-coded optical system can be restored to much higher resolution using deconvolution of images and a point spread function given by the coded target wavefront.

Auto-focusing actuator and camera module including flexible diaphragm for mobile phone camera and wireless capsule endoscope

Recent cellular phones have high-resolution, compact digital camera modules that have several millions of pixels. Although being small, such several mega-pixel camera modules definitely need to be able to execute auto-focusing and/or optical zooming in order to obtain precise images. Hence, image photographing devices having driving mechanisms that can move a lens group in the direction parallel to an optical axis have appeared such as piezoelectric type, linier motor type, and voice coil motor type. Although these technologies are already popular in existing digital cameras, driving mechanism for camera modules in cellular phones needs to be extremely improved because their requirements are totally different from usual digital cameras. Compact image photographing devices, which are installed in mobile apparatuses, should improve portability by reducing their sizes and weights and increase use-time of a battery by reducing power consumption. Weakened suspension (e.g. thickness is 0.02 mm or less) in order to minimize an elastic coefficient for drastic decrease of driving current frequently occurs permanent step-out of a lens group by plastic deformation of the metal suspensions when it comes to getting shocks from accidental drops of a handset. The proposed auto-focusing actuator using conductive polyimide as a flexible diaphragm satisfies these requirements of ultra slim cell phones. This polyimide suspension shows ultimate toughness when it comes to drop-test of cell phones. This actuator also shows high performance quite enough for several mega-pixel camera modules for ultra slim cellular phones; the moving range is up to 0.35 mm, the DC sensitivity is 0.2 mm/140 mA, and the resistance at the terminal is 22 Ohm, whereas the aperture is 6.8 mm, and the overall size is 10 × 10 × 3.95 mm. Most of all, the robustness against drop and shock has been dramatically increased, with no change of reliability under high temperature and high humidity condition, because of the flexibility of the conductive polyimide suspension.

Design and implementation of a scanner with stitching of multiple image capture

Instead of the flatbed scanner which moves slowly as it scans, we propose in this paper a new design of a high-speed and low-power scanner with a stitching of multiple image capture. We divide the area to be scanned into four parts, capture each image and then stitch these into a whole. Our design uses the compact camera module (CCM) advantages of high integrity, white balance, advanced calibration, and auto exposure for color and luminance, all of which reduce the software post-processing time. To solve the light reflection problem we propose an interleaved light source compensation method. To reduce power consumption and prevent light reflection among the four scan areas, we scan the four images one by one, during which a single CCM is turned on while the others are turned off. We use field of view (FOV) calculation to obtain the overlap area used by the stitching algorithms.

Effects of fabrication errors in the diffractive optical element on the modulation transfer function of a hybrid lens

Diffractive optical elements (DOEs) are often used to improve the performance of optical systems. However, when a blazed DOE is machined, shape errors can be generated in the discontinuity region of the DOE due to the finite radius of the processing tool. We simulated the effects of this shape error on the optical path and modulation transfer function (MTF) in a hybrid lens for a compact camera module. The decrease rate of the MTF was larger in the low-spatial-frequency domain and when the light entered at a low incident angle.

A fast focusing method for CCM autofocusing handlers

This paper proposes an autofocusing (AF) method for production of compact camera module (CCM). The CCM AF handlers are mainly used in the final CCM production stage to measure and adjust the lens focus of CCMs. To improve the productivity of CCM AF handlers, we propose an efficient focusing method adjusting the lens focus quickly. The max–min difference method is newly developed to compute the focus value efficiently, and two-stage searching method is also developed to find the best focus position quickly. Experimental results are presented to verify the usefulness of the proposed method.