Portable Consumer Electronic Devices Research Articles

Copper-Coated Graphite Felt as Current Collector for Li-Ion Batteries

Lithium-ion batteries (LIBs) undoubtedly are considered a viable option to meet the ever-increasing demands for portable consumer electronic devices and electric vehicles. To meet this requirement, intensive research is being conducted on increasing the volumetric and gravimetric energy density of LIBs as well as developing high-capacity electrode materials for LIB. In this study, a novel copper-coated graphite felt as a current collector is proposed for use as a constituent of LIB. Different type of Cu-coated graphite felt electrodes were synthesized. They were characterized by X-ray Diffractometer (XRD). To test its electrochemical performance Electrochemical Impedance Spectroscopy (EIS) and cyclic voltammetry (CVA) techniques were used. Materials with a specific capacity of up to 473 mAh∙g−1 were obtained. It was found that the nature of the capacity gain of carbon felt electrodes differs from that of graphite due to a different crystal structure. The use of a copper coating reduces the charge transfer resistance and increases the capacity of the material. Therefore, such new type of anode materials may be successfully used in LIBs.

A New Low Complexity Bit-truncation Based Motion Estimation and Its Efficient VLSI Architecture

A new motion estimation method and its hardware implementation are presented in this paper. In this method, all the frames are firstly gray coded. After that, the two most significant bits from the current frame and reference frame are used to compute the motion vector. Besides, a diamond search algorithm is used in place of the full-search algorithm. The motion estimation scheme proposed in the present paper is also verified to work on various standard video sequences. The experimental results thus obtained show that the proposed algorithm has an excellent balance of performance and computational complexity. External memory access has been reduced drastically by incorporating search pixel reuse. The resulting architecture is simple in terms of the hardware cost and power requirements while being faster than a recently reported similar architecture. The proposed architecture requires less hardware than comparable systems without compromising performance. The proposed architecture is therefore suited to be used in portable consumer electronic devices with real-time video applications in which power consumption is a concern.

A fast integrated deblocking filter and sample-adaptive-offset parameter estimation architecture for HEVC

Low power hardware acceleration cores for integration into real-time High Efficiency Video Coding (HEVC) codec for smartphones, tablets, camcorders, and televisions are in great demand. This demand motivates one for an efficient approximation of important power-consuming modules of HEVC including in-loop filters. This paper presents a hardware-efficient implementation of integrated deblocking filter (DBF) and sample adaptive offset (SAO) parameter estimation architecture for 16×16, 32×32, and 64×64 coding tree units (CTU) in HEVC. When the architecture is extended to HEVC-Test-Model (HM) Software, the luminance peak-signal-to-noise-ratio gets increased by 0.02 decibel, and the execution time of DBF and SAO gets decreased by at most 35% and 38%, respectively while compared to the reference algorithm. Moreover, it delivers rate–distortion performance comparable to the HEVC standard and reports mean-squared-error, structural-similarity (SSIM) index, and multi-scale SSIM (MS-SSIM) index of values 0.15, 0.9984, and 1, respectively for 4K video sequences. The architecture consumes minimum power, area, and energy equal to 9.83 milliwatts, 162 kilo-gate-equivalents, and 44 picojoules, respectively while supporting up to forty-six 8K frames per second. Additionally, it reports 78% smaller area and requires 75% less clock-cycles-per-largest-coding-unit as compared to the separate implementation of DBF and SAO with reference to HEVC. Such designs with low power, area, and energy can be integrated into a real-time HEVC codec for portable HEVC-compliant consumer electronic devices.

Design, Analysis and Performance Evaluation of Electrical Power Subsystem based on Triple-Junctions Solar PV Cells and SEPIC for a Conceptual 1u Cubesat Mission

This study aims to popularize low voltage power supply design especially for space satellite Cubesat mission and other portable consumer electronic devices. In this context, a preliminary design of an electrical power subsystem (EPS) is carried out for a conceptual 1u Cubesat mission in this paper. Mathematical modeling of the basic elements of the EPS is presented. Photovoltaic (PV) power generation system that is selected is made up of triple-junction solar cells, and the battery charging system based on lithium technology as well as the power conditioning converters are selected based on single ended primary inductance converter topology popularly abbreviated as SEPIC. Triple-junction solar PV cell results are verified by comparing with the datasheet values. A maximum power point tracking algorithm which is known as perturb and observe is implemented and proportional-integral controller is used for the SEPIC. All of these are well analyzed, mathematically modeled and simulated. Feasibility of the designed EPS is verified by comparing with similar devices from different manufacturers.

Digital Storage in Smartphones and Wearables [The Art of Storage

This "Art of Storage" column will look at some portable consumer electronic devices and then explore the digital storage for these devices while touching on other important design elements. I will discuss smartphones and the variety of new wearable devices, such as smartwatches. These devices capture and store personal content as well as store and play commercial content.

Porous cellulose/graphene oxide nanocomposite as flexible and renewable electrode material for supercapacitor

The increasing demand for portable, wearable, miniaturized and flexible consumer electronic devices requests the development of flexible and renewable energy storage devices. This paper reports a flexible and renewable electrode material for supercapacitor. The electrode material is made by preparing a porous structured cellulose/graphene oxide (GO) nanocomposite. The morphology of the nanocomposite is shown to be porous structure with a pore size about 10μm. The Fourier transform infrared spectroscopy of the nanocomposites exhibits that the cellulose and GOs are successfully grafted by a grafting agent, which results in uniform dispersion of GOs in the cellulose matrix. The electrical performance of the nanocomposite is evaluated by measuring cyclic voltammograms and galvanostatic charge-discharge curves. Low cost and sustainability of the cellulose and graphene oxide nanocomposite encourage its possible use for electrode material of flexible energy storage devices.

Probing Lithium-Ion Battery Safety in Mining Environments

Lithium-ion batteries are increasingly ubiquitous in portable consumer electronic devices, including laptop computers, cellular phones, and tablet computers. Lithium-ion batteries are also finding widespread deployment in many additional applications and settings, including underground mining environments, where lithium-ion batteries are used as electrochemical power sources for cap lamps, and in tracking and communications equipment.1,2 Battery safety is of paramount importance in any portable electronic device regardless of setting, and is particularly significant in enclosed and isolated areas such as passenger aircraft, or in underground mining environments, where potentially explosive methane/air mixtures can be ignited by a simple spark, which can be caused by shorting and thermal runaway of lithium-ion batteries. This presentation will summarize systematic abuse testing of different lithium-ion batteries used in underground mining safety and communication equipment, including lithium cobalt oxide (LiCoO2), lithium nickel manganese cobalt oxide (NMC), and lithium iron phosphate (LiFePO4) based cathode chemistries. Prismatic and cylindrical 18650 lithium-ion batteries were obtained from commercial vendors and subjected to both wedge and flat plate crush tests, in order to determine the relative safety of each cathode chemistry under two crush speeds and various states-of-charge (SOC). Battery voltage, case temperature and applied load were recorded for each crush test. Video recording of each crush test was also collected. In some cases, hard or soft electrical short circuits were caused by crushing the battery, resulting in thermal runaway, rapid temperature increases, and explosions or fires. Correlations will be drawn between choice of cathode chemistry, state-of-charge, type of crush test, and choice of atmosphere (air or methane/air mixtures), in order to determine the most suitable lithium-ion battery chemistry for underground mining applications. References 1) Dubaniewicz, T. H. Jr.; DuCarme, J. P. Journal of Loss Prevention in the Process Industries. 2014, 32, 165. 2) Dubaniewicz, T. H. Jr.; DuCarme, J. P. IEEE Transactions on Industry Applications. 2013, 6, 2451-2460.

Energy-efficient video decoding schemes for embedded handheld devices

Dynamic voltage and frequency scaling (DVFS) is an effective technique for reducing power consumption. Because of the increasing popularity of multimedia applications for portable consumer electronic devices, the importance of reducing their power consumption has become crucial. This paper proposes a table-based DVFS mechanism for frame decoding that can effectively reduce the power consumption of a processor by exploiting the frame-decoding complexity features. This proposed table-based DVFS predictor requires no prior knowledge on video decoders, and can be flexibly applied on different video codecs. This study implemented the table-based DVFS predictor on the PXA270 embedded platform and all benchmarks were encoded into various video coding formats, including H.264, VP8 and WMV formats. In addition, the proposed DVFS predictor was also ported on a modern platform NVIDIA JETSON TK1, and has demonstrated that the proposed algorithm can provide significant energy saving performance on high definition (HD) videos. The experimental results demonstrate that the energy consumption of decoding videos can be reduced from 6 to 21 %, whereas the frame drop rate is less than 3 %.

Graphene and Carbon Nanotube Applications in Mobile Devices

This paper presents potential carbon nanoelectronic applications in battery-powered mobile devices such as mobile phones and laptop computers. Based on the physical behavior of carbon nanotubes (CNTs) and graphene and the specific requirements for portable consumer electronic devices, the main challenges and restrictions for the adoption of carbon-based components by the industry are presented. The main emphasis is on electronic components, particularly transistors and radio-frequency applications. A circuit theory model is used to predict the feasibility of CNT transmission lines, and technical challenges that have to be solved before graphene transistors are suitable for mobile devices are presented. The performance of graphene transistors is compared with the corresponding parameters of silicon. In addition, other potential carbon-based applications in mobile devices aside from transistors such as displays and memory elements are outlined briefly.

The Optical Sensors Packaging Solution

The market demand for portable consumer electronic devices are growing exponentially, it is because of the electronics devices are installed with multiple functions and user friendly applications. When the electronics devices are equipped with multiple functions and applications, the power consumption of the electronics devices is also rising exponentially. Therefore, the need of reducing power consumption has become a very critical design in the electronics design as to provide end users with increasing battery life. In this paper, we focus on ambient light sensor, one of optical sensor devices which is developed to detect light in the manner similar to human eyes. It is a sensor that detect light so if it is dark the screen monitor brightness will dim down, when it is bright the screen monitor brightness will go up to compensate for the extra light around you so you can see the monitor comfortably.

Topics in integrated circuits for communications [Series Editorial

In the past ten years, we have witnessed rapid advances in communication technology that enabled more than an order magnitude increase in throughput and reduction in power consumption. The steep rise in available throughput has stimulated the growth of ubiquitous broadband services such as streaming of high-definition video contents, while on the other extreme, the steep drop in power consumption, in particular for short-range radio technologies, has enabled personal area connectivity for all kinds of portable consumer electronic devices, such as headsets, cell phones, and cameras. Current third-generation (3G) mobile devices easily support data rates on the order of 1-10 Mb/s, while quasi-static devices can easily support up to 600 Mb/s with wireless LAN based on IEEE 802.11n. For short distances, Bluetooth and ZigBee connectivity technology consume power as low as 10-50 mW.

High Volume, Low Cost Multi Die Packaging Using Conductive Polymer Interconnect

Wire bonding multiple die in a single package, PoP (Package on Package) and, more recently, TSV (thru silicon via) approaches are often considered for small, portable consumer electronic devices. Conductive polymer interconnect is a new approach that provides cost and size advantages for a wide variety of applications. Conductive filled polymer materials are well suited for chip to package and chip to chip interconnect. They are compatible with existing equipment and material sets used in a typical semiconductor assembly facility, and capital costs for adding this capability are relatively low. This method also offers size and cost advantages for single die packaging of image sensors and other die, where there is a requirement to connect to the front side of a die from the backside, without occluding the front surface. Wafer level packaging (WLP) methods and array processing greatly reduce costs, making the technology competitive with traditional wire bond techniques.

Non-Volatile Memories for Removable Media

NAND Flash memory has become the preferred nonvolatile choice for portable consumer electronic devices. Features such as high density, low cost, and fast write times make NAND perfectly suited for media applications where large files of sequential data need to be loaded into the memory quickly and repeatedly. When compared to a hard disk drive, a limitation of the Flash memory is the finite number of erase/write cycles: most of commercially available NAND products are guaranteed to withstand 105 programming cycles at most. As a consequence, special care (remapping, bad block management algorithms, etc.) has to be taken when hard-drive based, read/write intensive applications, such as operating systems, are migrated to Flash-memory based devices. One of the basic requirements of the consumer market for data storage is the portability of stored data from one device to the other. Flash cards are the actual solution. A Flash card is a nonvolatile ldquosystem in packagerdquo in which a NAND Flash memory is embedded with a dedicated controller. This paper presents the basic features of the NAND Flash memory and the basic architecture of Flash cards. We provide an outlook on opportunities and challenges of future Flash systems.

A Method for Assessing the Potential for a Dermal Burn Hazard From Malfunctioning Consumer Electronic Devices

We developed an approach to adapt the ASTM C1055-03 Standard to assess the potential for contact burn injury from portable consumer electronic devices. The approach involves measuring the maximum temperature profile during the fault and devising a way to reproduce these temperatures in an exemplar device in a controlled manner for thermesthesiometer measurements. By comparing the results of the thermesthesiometer measurements to the contact burn injury threshold data published in ASTM C1055-03 and various guidelines for unintentional contact times, we were able to predict whether a potential hazard exists and verify result with "finger tests." We applied this method on a number of occasions to assess the likelihood of a contact burn injury resulting from a fault arising inside portable consumer electronic devices.

Human Powered Piezoelectric Batteries to Supply Power to Wearable Electronic Devices

Consumer electronic equipments are becoming small, portable devices that provide users with a wide range of functionality, from communication to music playing. The battery technology and the power consumption of the device limit the size, weight and autonomous lifetime. One promising alternative to batteries (and fuel cells, that must be refueled as well) is to use the parasitic energy dissipated in the movement of the wearer of the device to power it. We analyze in this work the current state-of-the-art and the future prospect of energy conversion from mechanical movement in the human environment to electrical energy based upon the piezoelectric effect. This is an interdisciplinary field where material technology and electrical circuits have to advance together to improve the conversion efficiency in order to reach the energy demands of the typical portable consumer electronic devices that will become in this way autonomous wearable devices.