HP L1940 Service Manual page 73

GENERAL PRODUCT SPECIFICATION(Continued)
patterns may be visible when viewed from off-axis.
10.7 Optical Light Leakage
There shall not be visible light from the back-lighting system around the edges of the screen as seen from a
distance of 20 inches from the screen with an overhead light level of 10 lux. The manufacturer shall furnish
samples of the monitor with each supported LCD module showing the maximum amount of light leakage. This
sample shall be considered the
have a lesser amount of light leakage.
10.9 LCD Inspection
Put LCD panel on inspection table and illuminate the panel with a daylight fluorescent lamp located above the
panel surface such that the illuminance at the LCD panel is between 1000 lux and 1500 lux. Defect limits are
given in Table 3 for the combined defects from this inspection and the electrical and mechanical defects from
Table 4.
Average Diameter
smaller of (L+W)/2 or L/20+2W
<0.1mm
0.1 mm
0.31 mm
0.51 mm
1.26 mm
2.51 mm
Greater than 3.75 mm
Allowable distance between spots of two sizes is the minimum separation number for the smaller spot.
Therefore, if there are two spots, 1.30 mm and 0.4 mm in diameter, they must be at least 15 mm apart.
11.0 USB 2.0 HUB
The USB hub shall be powered by the internal supply of the monitor. The communication protocol shall comply
with USB specification revision 2.0. A single upstream connector shall serve as connection to the CPU or other
USB hub. Each of the 2 downstream ports shall include current-limited power of 5VDC at 500mA for use by an
attached device.
USB Signals
USB signals shall meet the timing and signal level standards for high speed devices set forth by industry
standard USB specification revision 2.0. Each downstream port shall provide 5VDC at up to 500mA for use by
an attached USB device.
Communication Protocol
USB connections shall be established via 4-conductor USB cables. USB cables must be shielded in
accordance with the USB specification for high speed devices.
19 inch LCD Monitor
TYPE
BRAND : HP L1940
2004-08-31
Jacky Lee
worst case
Table 4 Defect Inspection
Acceptable
Number
Non countable
0.3 mm 10
10
0.5 mm
5
1.25 mm
2.5 mm 3
3
3.75 mm
none
:EJ6B50/02
2004-08-31
light leakage sample and all panels used for production shall
Minimum
separation
N/a
15 mm
15 mm
15 mm
25.4 mm
25.4 mm
Not applicable
8639 000 15804
590
28 23
HP L1940 73
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