Acer X223 X223W LCD Service Guide - Page 7

6 ACER X223W Go to cover page 1. Product Specification (continued) 1.3.8 Display Communications Channel The monitor assembly shall provide a display communications channel that conforms to VESA DDC2Bi hardware requirements. This configuration shall contain the 128-byte EDID file as specified by VESA EDID standard.The monitor should not write to the EDID file for the first two minutes of operation following power-up UNLESS some action taken by the user or the host CPU forces the write (for instance, requesting the serial number via the OSD). Furthermore, it is recommended that CMOS switches be incorporated to isolate the DDC IC from outside connections while the EDID Fault Management is being updated. This is to prevent corruption of the data by attempts to read the data while it is being changed. 1.3.9 Firmware Update Function (same ISP function) The update firmware need through from the D-Sub connector, use DDC I2C bus to do update firmware. 1.4 PANEL ELECTRICAL 1.4.1 General Requirements The panel used as the display device shall be an WSXGA resolution,20/22W, TFT-LCD.This panel shall be approved for use in this monitor. 1.4.2 Panel Timings The controller included with the monitor shall translate all video timings from the CPU that meet the timing requirements listed in Panel specification into timings appropriate for the panel. Under no circumstances may the controller supply the panel with timings that may result in damage. The controller shall insulate the panel from the CPU , so that the panel shall always be driven per it's own specification regardless of the timings being sent from the CPU. 1.4.3 Polarizer Hardness The outer face of the front polarizer panel shall be covered with a coating with a # 3 hardness value . 1.4.4 Backlight Requirements 1.4.4.1 General Requirements The backlight assembly shall be designed to support field replacement at the customer site or authorized service center. The lamps shall have a continuous operating life of at least 40,000 hours at 25. The operating life is defined as having ended when the illumination of light has reached 50% of the initial value. The lamps shall extend a sufficient amount from the edge of the light guide that sputtering over the life of the lamps shall not cause degradation of the luminance uniformity (such as non-illuminated bands along the edges of the display). 1.4.4.2 Lamps Startup Time The backlight lamps shall start about 2 sec of the time the monitor power switch is pressed or the monitor is restarted from a power - down mode .The starting time shall stay about 2 sec. for the minimum expected life of the lamps. Test conditions are as follows : Ambient Light 1.0 lux Temperature 10℃ Inactive Time 24 hours 1.4.5 Defects 1.4.5.1 Visual Inspection The LCD panel shall be inspected with all pixels set to white,black , red , green , and blue. The color variation, brightness variation , and overall appearance must not be perceived as poor quality by Lite-On . Areas and / or parameters considered questionable shall be subjected to detailed measurements . 1.4.5.2 Display Degradation Over the life of the product , variation of the parameters specified in Panel specification shall be maintained within reasonable limits.The panel must not exhibit any significant defects while in operation ( excluding the CCFL operation ).This does not in any way change the warranty given by the panel manufacturer . 1.4.5.3 Light Leakage Except for the active display area , there shall be no light emission visible from any angle from any other part of the display . For this test , the ambient illumination must follow panel's specification. 1.4.5.4 Allowable Defects No cosmetic defects are allowed except those specified below.The conditions of visual inspections are as follows : For P20/22 W Series. ■Viewing distance is to be approximately 35-50cm ■Ambient illumination is to be 300 to 700 lux. ■Viewing angle shall be at 90 degree. ■Defects not apparent within one minute shall be ignored.