Why Laptop battery reduces its efficiency? Tech Focus 9


Laptop battery is a kind of Lithium Ion ( Li-ion) battery which has features like high efficiency, slow discharge rate, best energy to weight ratio etc.Unlike other rechargeable batteries, Lithium ion battery uses Lithium as the active material. During discharge, the lithium ions move from the negative electrode to the positive electrode. The flow of lithium ions reverse during charging. Lithium Ion battery outperforms other types with its features like High open circuit voltage that deliver high power at low current rate, Low self discharge rate of 5-10% per month etc. But along with these advantages, lithium ion battery has demerits also. Memory effect, self discharge, over heating etc are the most important drawbacks of Laptop battery. Let us see how this happens and the solutions to prevent this.
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Why OLED screen looks brighter than LCD screen? Tech Focus 8


 

New version Mobile phone, Laptop, TV etc uses OLED screen to give brighter screen display. The advantage of the display is that, the screen can be viewed from any angle without glare and the image will be more clear and sharp. OLED (Organic LED) is a 100 – 500 nanometers thick semiconductor film that emits light through Electrophosphorescence. OLED is also called as OELD (Organic Electro Luminescent Device) and made up of thin layers of organic materials that emit Red, Green, Blue and white light. The OLED screen is much thinner than the LCD screen.

The Organic material in the OLED consists of Amorphous and Crystalline molecules without a definite arrangement. These molecules are arranged in different layers. When a potential difference is applied between the anode and cathode of OLED, current flows through the organic layer of OLED. During the flow of current, cathode layer emits electrons to the emissive layer. Anode then gives electrons from the conductive layer creating holes. These electrons combine with the holes in junction between the emissive and conductive layers. When the electrons combine with holes, the energy of electrons is emitted as photons. Colour of the photons depends on the type of the organic material in the emissive layer.Polymer light-emitting diodes (PLED), also Light-Emitting Polymers (LEP), are used in electroluminescent conductive polymer. Typical polymers used in PLED displays include derivatives of Poly(p-phenylene vinylene) and Polyfluorene.

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Why LCD Screen damage easily? Tech Focus 7


 

Liquid Crystal Display is a kind of screen filled with a polarizing fluid between two glass plates. This liquid is an electrically controlled fluid trapped between two transparent polarizing sheets. The polarizing axes of the two sheets are aligned perpendicular to each other. The polarizing liquid is filled in cells which have electrical contacts to permit the entry of electrical field into the cells. When an electric field is applied, the molecules in the liquid align themselves with the field, inhibiting rotation of the polarized light. As the light hits the polarizing sheet perpendicular to the direction of polarization, all the light is absorbed and the cell appears dark.

The whole display has array of segments called Pixels which may be coloured or monochrome or both. The pixels may be divided into Sub pixels of Red, Green, and Blue by additional filters as in the case of LCD TV. These pixels are arranged in front of a light source with a reflector. Each sub pixel can be controlled independently to produce thousands or millions possible colors for each pixel. The liquid crystal makes the light to pass through the other by twisting the polarization of light entering one filter. By applying a small electric charge to transparent electrodes over each pixels or sub pixels, the molecules of the liquid crystal are twisted by electrostatic forces. This reorientation of the liquid crystal makes the image.

LCD screen is too sensitive to mechanical shocks and heat , since the pressure may squeeze the fluid present in between the plates which can cause its permanent damage. Excessive heat can change the physical properties of the liquid so some part of the screen may damage and appear as black spots or segments.

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How Online UPS gives clean AC? Tech Focus 6


UPS is the essential part of the PC for providing uninterrupted power to run the system and to protect data. In the event of a power failure or voltage drop, PC will draw power from the UPS and will run for a prescribed time depending on the capacity of the battery. The change over time from the mains to battery power is a fraction of a second, so that the computer will not shut down. This is essential to protect the data in the computer. Basically there are two types of UPS. These are Offline UPS and Online UPS. Off line UPS passes the input AC to the output sockets if the AC power is available. The advantage of the Online UPS is that, it clean up the AC waveform by converting it into DC then reconverting this DC to fresh AC.
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How to maintain Maintenance Free Battery? Tech Focus 5


“My UPS is not giving sufficient back up”. This is the most common complaint raised by PC users. It is not the fault of the UPS, but is due to the poor maintenance of its battery. Sealed batteries are used in UPS, Emergency lamps etc do not require water and acid top up. There is no water loss in these batteries during the charge/discharge cycle and it can be positioned in any direction like vertical, horizontal etc. These sealed batteries are known as SMF (Sealed Maintenance Free) or VRLA (Valve Regulated Lead Acid) batteries and they work on the oxygen recombination principle. SMF battery is totally maintenance free and has longer cyclic life, thus compensating the initial higher cost. One of the important aspects of battery life in relation to the use of equipment is the cut off voltage set in the equipment. If properly maintained, the sealed battery can give sufficient back up time. Let us see the tips to increase the life of UPS and Inverter battery.
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How Curing Light works? Tech Focus 4


Curing light technique is widely used in chemical engineering, polymer processing and medicine to generate heat in the targeted area. Infrared, Ultra violet, Halogen light etc are usually used in curing light technique. With the introduction of high power LEDs, blue LED light is now used as a source for curing light technique.Dental curing light is  used by the dentists for treating tooth cavities or filling root canals.

The new light curing technique is based on Blue LED. High power LED (3 or 5 Watts) is used as the light source which emits blue light in the wave length of 430-485 nano meters. Light intensity can reach 1000 milli watt per cm2 and the timing of curing usually 10 -20 seconds can be set using a timer. The LED lamp hardly generates heat so the operation is comfortable. The light output can be adjusted as Fast, Ramp or Pulse depending on the requirements.
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How TFT Monitor gives clear image ? Tech Focus 3


Quality of image is far better in TFT monitor than the LCD monitor, This is because TFT monitor uses Thin Film Transistor (TFT) technology to enhance the contrast and addressability of the image. It is a variant of the  Liquid Crystal Display (LCD) that uses  matrix LED technology to provide clarity, brightness etc of the monitor. TFT monitors are now common in TV, Computer, Mobile phone etc.

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