Topway

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[edit] Topway LCD: LM6023B, LMB162NDC

[edit] backlight LED
  • a 24hrs(un-power off) long run lasting a long period over a year, start testing on afternoon 16 july 2008
    • with full pwr backlight LED: +3.3V -- backlight LED -- GND
    • with partial pwr backlight LED: +3.3V -- 10ohm res. -- backlight LED -- GND

[edit] LCD glass signal connection

[edit] LCD Life Time

  • The old model LCD LM6023B has some problems after using for a period due to technical problem

on the old structure LCD.

  • The old model make up of Metal Frame, LCD, Rubber Connector, COB and Heat Seal.
    • Heat seal paper, Nippon Graphite, is connected between LCD and COB horizontally.
      • When there is any aging problem on the heat seal paper,missing horizontal line or dimmed down may happened. According to the report from our supplier, Running under higher temperature or adverse situation, the life time of LCD will be shorten.
  • Now, the new model LCD doesn't consist of the heat seal paper, so the life time of LCD will much longer than that of old model.

[edit] LCD Lifetime test under different temperature

  • set up
    • settle down the Environment Chamber
      • prepare fan
      • connection of electric supply
      • high temperature resist cable
  • LCD
    • 10 ohm sand 0 ohm resistor LCD
    • remove the plastic cover
  • Test
      • set up different temperature
        • eg. 13,25,40,25,13,0,-15,0,13,25
        • record different result under different condition

[take photo]

[edit] LCD Backlight

  • The LCD can be enlarged the lifetime of backlight by not always 100% turn ON the backlight LED.
  • A high frquency PWM is used to control a transistor and push the backlight LED.
    • the high frequency will not affect the life time of backlight LED, because if the frequency is high enough, it just look like a DC. However, if a lower frequency is used, flicking on the LCD may occurs.


[edit] Troubleshooting
  • Problem: just a touch, whole screen blank, but backlight still ON
    • Reason:
      • static electricity lets the module reset pin drop, then reset whole module
      • collect Static Electricity from its front black color Enclosure
      • its original circuit fr. Topway is "front black color Enclosure" shorted to GND circuit.
      • this circuit lets the "Static Electricity" going into "front black color Enclosure", then go into Gnd circuit, and let the GND circuit in un-stable situation.
    • Solution:
      • Option 1
        • each around 10min. to software reset once
        • dis-adv. -- it lets the screen always refresh, however, when the screen blank, user must wait a while to let the screen recover.
      • Option 2
        • adding the following circuit between host reset control pin and module reset pin
        • adding a 0.04uF Y-Cap. bet. metal case(Earth) and Digital Gnd, they should have 60V
        • dis-adv. -- it seems does not apply to this problem.
      • Option 3
        • Cut JP1 which is short the "front black color Enclosure" and GND circuit, i.e. seperate them
        • Solder a wire between "front black color Enclosure" and local Enclosure
  • Problem: backlight dim down
    • Conditions:
      • LED backlight and its circuit is Vcc-LED(3.3V)-Resistor_in_82_ohm(1.3V, i.e. 20mA)-GND
    • Reason: LED is 50000hrs, assume 10000hrs(around 1 yr) for good lighting
    • Solutions:
      • serial a resistor in our circuit board for lower the backlight current AND get a LM6001
      • make a PWM to control the power of backlight to damper in some non-working time
  • Problem: some rows missing
    • Conditions:
      • (guessingly) environment in day time with air-condition, night time without air-condition, then humidity
    • Reason: humidity affect the paper tape to glass of LCD
    • Solutions:
      • another model with diff. arch to avoid this (model fr. LM6023B to LM6023ADW)


[edit] Backlight

[edit] yellow-green LED
  • long life
  • heat
[edit] white LED
  • around 6000hrs dim down to 50% bright
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