LCD Question and Answer

1.Question:What types of LCD and LCD Module?

    Answer:TN:Twisted Nematic

                 HTN:High Twisted Nematic

                 STN:Supper Twisted Nematic

                 FSTN:Formulated STN

                 TFT:Thin Film Transistor

                 COB:Chip On Board

                 COF:Chip On Film

                 COG:Chip On Glass

                 TAB:Tape Automated Bonding

2.Question:What is the LCD character?

    Answer: LCD:Liquid crystal displays (LCDs) are a passive display technology. This means they do not emit light nor any radiation; instead,

                   they use the ambient light in the environment.

               1. Operating temperature and storage temperature: Operating temperature 0℃~50℃,storage temperature -20℃~70℃

                    Wide range LCD operating temperature -30℃~80℃,storage temperature -40℃~100℃

               2. Contrast:TN LCD:DUTY 1~1/8 Cr >5.

                    DUTY 1/8~1/16 (1/8 included),Cr >3.

                    STN LCD:Cr > 3 for blue and gray type. Cr〉5 for yellow, green, yellow and green type

                3. Response time: TN LCD:Rising time < 250ms; Falling time < 300ms. STN LCD:Rising time<400ms;  Falling time < 400ms.

                4. Viewing angle:TN LCD:DUTY 1~1/8〉 30°; DUTY 1/8~1/16,> 25°. STN LCD:DUTY > 1/64,> 50°; DUTY < =1/64,> 30°.

                5. Threshold Voltage:Minimum 0.7V for TN type under normal atmospheric temperature,

                     minimum 0.8V for STN type. Threshold voltage may rise if LCD has a wide range temperature.

3.Question:What is the Caution for Operation with LCD and LCD Module?


                1-1. MOUNTING METHOD

                    The panel of the LCD module consists of two thin glass plates with polarizers which easily get damaged since the module is fixed by
                    utilizing fitting holes in the printed circuit board. Extreme care should be taken when handling the LCD modules.
                    When cleaning the display surface. Use soft cloth with solvent (recommended as below) and wipe lightly.
                    -Isopropyl alcohol -Ethyl alcohol
                    Do not wipe the display surface with dry or hard materials that will damage the polarizers surface.
                    Do not use the following solvents:
                    -Ketones solvents
                    -Aromatics solvents
                   The LCD modules use C-MOS LSI drivers. So we recommend that you connect any unused input terminal to Vdd or Vss,
                    Do not input any signals before power is turned on and ground your body,
                    Work/assembly table and assembly equipment to protect against static electricity.
                    Modules use LCD elements,
                    Do not subject to excessive shocks by dropping the units. -To prevent modules from degradation,
                    do not operate or store them in sunshine or at high temperature/humidity.
               1-5.CAUTION FOR OPERATION
                    It is indispensable to drive LCM within the specified voltage limit since the higher voltage than the limit will shortens LCM life.
                    Response time will be extremely delayed at lower temperature than in the specified operating temperature range and on the other
                    hand at higher temperature LCD will show dark color in them. However those phenomena do not mean malfunction or out of order
                    with LCD, which will come back in the specified operating temperature range. If the display area is pushed hard during operation.
                    Some font will be abnormally displayed but it resumes normal condition once turning off A slight dew depositing on terminals may c
                    ause Electro-chemical reaction resulting in terminal open circuit. Under the maximum operating temperature, 50%RH or less is
                1-6 STORAGE
                    In the case of storing for a long period of time (for instance, for years) for the purpose of replacement use, the following ways are
                    recommended -Storage in a anti-static polyethylene bag with the opening sealed so as not to enter fresh air outside in it, and with
                    no desiccant. -Placing in a dark place where neither exposure to direct sunlight nor to light, keeping temperature in the specified
                    storage temperature range. -Storing with no touch on polarizers surface by anything else. (it is recommended to store them as

                    they have been contained in the inner container ).
                     It is recommended to crash damaged or unnecessary LCD into pieces and wash off liquid crystal by using solvents such as acetone
                     and ethanol, which should be burned up later. When any liquid crystal leaked out of a damaged glass cell comes in contact with your
                    hands, please wash it off immediately with soap and water.
                    2.PRECAUTION FOR USE
                 2-1. A limit sample should be provided by the both parties on the occasion when the both parties agree its necessity. Judgment by
                     a limit sample shall take effect after the limit sample has been established and confirmed by the both parties.
                 2-2. On the following occasions, the handling of problem should be decided through discussion and agreement between
                     representative of the both parties When a question is arisen in this specification. When a new problem is arisen which is not
                     specified in this specifications. When an inspection specification change or operating condition change in customer is reported to
                     Link-Sun and some problem is arisen in this specification due to the change. When a new problem is arisen at the customer's
                    operating set for sample evaluation in the customer size.

4.Question:LCD Optical & Color Mode?


TN Type

                     Positive display,black display with white background
                     Negative display, white display with black background
                     LC twist angle stays at 90o for TN LCD

STN Type

                     Yellow & green mode, blue black display with yellow & green background
                     Blue mode, white display with blue background
                     Gray mode, brown blue display with gray background
                     Because twist angle can stay at 180o~240ofor STN type,this type is applicable to higher drive


                     Positive and Negative display can be accomplished for FSTN type with multi-drives
                     Negative FSTN display,white character with black background
                     Positive FSTN type,black character with white background
                     FSTN is a type of display in which single or double compensation films are attached to STN LCD panel so that the interfering colors

                     can be compensated

Holographic FSTN

                     This is a type of LCD display in which a holographic film is attached to the FSTN LCD panel

                     With holographic film,bright background color pleasant to eyes will emerge

5.Question:LCD Connector?

    Answer:Rubber connector

                     ompression-type connector where current flows between the LCD panel and the electronics of the printed circuit board through

                     a rubber connector

                     Since the pin pitch can be reduced,this connector is suitable for a large capacity LCD .

Pin connector

                      A connector soldered to the printed circuit board
                     The type of the pin: 2.54mm,2.0mm,1.8mm.
                     It can be used to such thick glasses:1.1mm,0.7mm,0.55mm

Heat seal connector

                      A connector where the LCD and the printed circuit board are connected using a heat crimping machine.(it is also possible

                      to solder them)
                     Since the connector has flexibility ,the LCD panel can be mounted easily.


                     TAB is the abbreviation of Tape Automated Bonding.
                     A connector where the LCD and the IC are connected using a ACF
                     It can reduce the capacity of the LCM


                     COG is the abbreviation of Chip On Glass
                     A connector where the LCD and the IC are connected using a ACF
                     It can reduce the capacity of the LCM

6.Power Supply Schematics?

    Answer: Interface with MPU
                     1.1 Character type LCM (Controller ks0066)

                     1.2 LCM using controller SED1520D0A(NJU6450)

                     1.3 LCM using controller SED1520DAA(NJU6452

                     1.4 LCM using controller KS0108(HD61202)

                     1.5 using controller T6963C

                     2 Power supply

                     2.1 Single power(Character type)

                     2.2 Dubble power(Character type and Graphic type)

                     2.3 Dubble power (Graphic type)

                     2.4 Single power (Graphic type)