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Liquid Crystal Display
(48) of clock (CLK) cycles from the end of the HSYNC
pulse and the drive signals are ter mi nat ed a fi xed num-
ber (16) of CLK cycles prior to the next HSYNC pulse.
In DISPLAY ENABLE mode, the pix el drive signals
are applied to the pixels only while ENABLE signal is
present. This signal is typically present 4-48 CLKS after
the end of the HSYNC pulse and 2-16 CLKS prior to
the next HSYNC pulse. All YORK applications oper-
ate in the DISPLAY EN ABLE mode. The state of the
ENABLE (Display In ter face Board J1-27) signal from
the Microboard plac es the Display in the desired mode
as follows:
• SHARP LDQ10D367 & LDQ10D421 Dis plays -
When ENABLE maintained "low", display op er ates
in fi xed mode.
• NEC NL6448AC33-24 Displays - When EN ABLE
maintained "high" or "open", display op er ates in
fi xed mode.
• LG SEMICON Display does not have the fi xed
mode feature.
As described above, in OptiView Control Center ap pli -
ca tions, the Display scan is left to right, beginning with
the top row and continuing sequentially through the
rows to the last row. However, in Display ap pli ca tions
other than OptiView Control Centers, image reversal
is sometimes required. In image reversal applications,
the scan is re versed; the scan is right to left, beginning
with the last row and proceeding to the top row. The
SHARP or NEC Display is placed in the NORMAL
or RE VERSE scan mode by the volt age levels on the
Dis play In ter face Board J1-30 and J1-31 (display con-
nec tor CN1-30/31). These voltage lev els are de ter mined
by the con fi g u ra tion of Wire jumpers P30 and P31 on
the Display In ter face Board (ref. Fig. 28). The Display
reads these volt age levels and au to mat i cal ly assumes
NOR MAL or RE VERSE scan op er a tion. Refer to DIS-
PLAY IN TER FACE BOARD section that fol lows for
jumper con fi g u ra tions.
Displays by different manufacturers can require dif fer ent
timing and control signals. The Microboard must know
which Display is present in order provide the cor rect
signals. Therefore, when AC control power is fi rst ap-
plied to the OptiView Control Center, as part of the
power-up sequence, the Microboard reads the Panel ID
wire jump ers P1D0 - P1D3 on the Display In ter face
Board and de ter mines which Display is present. It can
then pro vide the correct timing and con trol sig nals to
pro duce the graph ic image, as required by the Dis play
man u fac tur er. Since the Display Interface Board iden-
ti fi es the Dis play for the Microboard, there is a dif fer ent
46
Display Interface Board required for each Dis play ap-
pli ca tion and each has a unique jump er con fi g u ra tion
that iden ti fi es the Dis play. A com plete ex pla na tion of
this process is in clud ed in the pre ced ing "Microboard"
sec tion and the "Display Interface Board" sec tion that
fol lows.
The DC power source to operate the Display is pro vid ed
by the Microboard J5. Some Display man u fac tur ers re-
quire +5VDC; others require +3.3VDC. The po si tion of
Microboard Program Jumper JP2 de ter mines which of
these power sources is supplied to the Dis play. JP2 must
be positioned according to the Dis play manufacturers
requirements. Refer to Table 1, "Pro gram Jumpers".
The Backlight Lamp provides the illumination for the
dis play. Av er age lamp life is 25000 hours (2.9 years).
Some dis plays use one lamp. Others use two lamps.
Lamps are re place able, but not in ter change able be tween
dif fer ent dis plays. Each Display man u fac tur er spec i fi es
the re quired lamp for their display. Refer to re place ment
parts list for ap pro pri ate re place ment lamp. Ser vice
re place ment lamps are stocked in the YORK Ser vice
Parts Dis tri bu tion Center. The lamp is il lu mi nat ed by
applying a high volt age AC (500 to 1500VAC) to it.
This il lu mi na tion volt age is created from a low lev el DC
voltage (+12VDC or +5VDC as required by the Dis play
man u fac tur er) by the Backlight Inverter Board. Lamp
bright ness is con trolled by varying the high volt age AC.
The great er the voltage the brighter the il lu mi na tion.
The lamp is con trolled by on/off com mands and bright-
ness con trol sig nals applied to the Backlight In vert er
Board from the Microboard. The Microboard Pro gram
de ter mines when the lamp is turned on and off and the
lamp bright ness. Each Dis play man u fac tur er specifi es
the Backlight Inverter Board to be used. Therefore,
it will vary ac cord ing to the Display man u fac tur er.
The ribbon ca ble that con nects the Microboard to the
Back light Inverter Board also varies according to the
Dis play man u fac tur er's re quire ments. Refer to Fig. 29
to 31. Microboard Pro gram Jump ers JP3, 4, 5, 7 and 8
de ter mine the voltage levels of the control sig nals sent to
the Backlight In vert er Board and must be con fi g ured
per the Dis play man u fac tur er's re quire ments as listed
in Table 1. A detailed description of the op er a tion of
this board is in the "Backlight In vert er Board" sec tion
that fol lows. Also refer to the pre ced ing "Microboard"
sec tion for a de tailed de scrip tion of the Lamp Dimmer
circuit.
The actual Display that is installed in the OptiView
Con trol Cen ter of the new chiller is determined by the
Dis play man u fac tur er contractual agreement in place
dur ing the time of OptiView Control Center production.
FORM 160.54-M1(503)
YORK INTERNATIONAL
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