Touchscreen phones

Touch screen phone problems

  In the recent years, touch screen phones have rapidly become the most popular. This is explained by the rapid development of modern technologies in the sphere of mobile phones, and also simplicity and convenience of touch control for users. In modern mobile phones touch control allows to use all functions and applications maximally comfortably.

  Today distinguish two types of touch screens: resistive and capacitive.

  • - Resistive screen

  The screen of this type is based on two layers, possessing certain resistance. Top is a flexible layer (plastic, called touchscreen) bottom - hard layer. Pressuring on an epiphase there is its contact with an understratum, and control electronics calculates the coordinates of click point.

  The main dignity of this screen is sensitiveness to any touch: it is possible to click on the screen with gloved hands, stylus or any other hard objects. Another important advantage of resistive screen is its stability at phone’s falling. This screen can be scratched, but to break up it very difficult, because it is a plastic.

  Despite all advantages of resistive screen, also there are some disadvantages. Touch screen constantly undergo mechanical loads during phone’s exploitation, that’s why there is a high risk to lose its efficiency. Another disadvantage of resistive screen is its low light transmission (no more than 85%). Having a protective layer, however there is still a possibility to damage a screen and violate its work. The surface of plastic is easy to cut and it cannot withstand too high temperatures.

  In case of a failure of touch screen (deterioration of detail or mechanical damage after falling) it is necessary to substitute faulty touchscreen by new one. It is necessary to take off the old one, before installing a new one.

  In order to get to the screen it is necessary to disassemble a mobile phone. To do this, remove the back cover of the phone, the battery and SIM – card. When back of the phone is taken off, carefully put aside system board and a flex is pulling out of the socket. This procedure is needed in an order to separate the front part from the main part of the phone.

  Then carefully disconnect a display and extract it from a corps. A touch screen is fastened on a corps by the specialized glue, that’s why it must be warmed at a temperature 100-120 degrees for 2-3 minutes to soften the glue. After warming the glue shall be cut by means of scalpel. Then a touch screen can be disconnected from a corps.

  Before new touch screen’s installing the specialized glue is applied to its basis for detail’s fixing; a display is cleaned out from a dust under strong pressure of air. After that procedure is possible to glue a new detail to the corps.

  The prepared screen and system board must be placed back in a corps, attaching the flex of display to the board. Need to check the efficiency of new detail, before the phone will be gathered completely. To do this, the battery is connected to the system board and phone must be turned on. If the screen correctly responds to the clicks, the detail is correctly installed. Only after careful verification it is possible to gather the phone. At the end of mobile phone’s repair it must be tested one more time. Only after complete inspection we can say confidently that the repair has been completed successfully.

  • - Capacitive screen

  The screen of this type based on ability of human body to conduct an electrical current. A capacitive touchscreen is a glass panel, which surface is coated with resistive material. When you touch the screen with finger there appear an electric current, and a special controller calculates the coordinates of click.

  Important advantage of this screen is its durability. In spite of regular loads, the risk of efficiency loss is small. Comparing with resistive screens, they have high light transmission (90% and more).

  Along with advantages, there also are disadvantages of capacitive screens. The weak point of this type of screen is possibility to work only under the influence of conductive material. Screen will not react on touching by stylus, by any other hard object or by gloved hands.

  Another capacitive screen disadvantage is its instability at phone’s falling. Glass is easy to break.

  Principle of replacing the defective touch screen at capacitive screen is similar to the principle of replacing the touch screen at resistive screen. The only difference is that touchscreen at capacitive screen is glued to the display, but not to the corps.

  But in some last models of mobile phone touch panel and display is one module, which considerably simplifies repair of defective detail’s replacement. It is not necessary to spend a lot of time on separation of touchscreen and display, and then to glue the touchscreen to the display. The new module is screwed on the corps or is glued to the corps of phone by specialized glue. There also are prepared modules in a corps, like in: Samsung Galaxy SII, Samsung Galaxy SIII, Samsung Galaxy Note. This type of module significantly reduces the amount of time for repair.

  It is necessary to put missing details from old module to the prepared module, such as: speaker, antenna, flex of system connector and decorative buttons. Then system board is put in module, display’s flex is attached to the display and back lid of phone is screwed on corps. In completion of repair it is necessary to check a new detail: turn on phone and see, does the screen respond to click; do the decorative buttons work; is there any sound. If all works correctly, repair is successfully completed.

  Touch screen phones require especially thorough and maximally careful handling. If there is a fault, the best decision of this problem will be repair in service center.

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