Pioneer PDP-4280HD, Service Manual

Page: 73 / 176

PDP-4280HD
73
5 6 7 8
5 6
7
8
C
D
F
A
B
E
5.5.2 FUNCTION OF DECREASING THE BRIGHTNESS LEVEL
High-temperature protection function 1/
panel protection functions 1, 2, and 3
High-temperature protection function 1/panel
protection: The limit for the maximum count
of plasma discharge will be gradually
decreased if the panel temperature reaches
70
°
C.
High-temperature protection function 2
The count of plasma discharge with regard to the APL will be
decreased if the panel temperature becomes 65
°
C or higher.
2000
700
APL (average picture level)
If the panel temperature (TEMP1) reaches 70
°
C, the limit for the maximum count of plasma discharge will be gradually
decreased to lower the temperature of the panel.
• This function is activated based on the TEMP1 temperature.
• The limit for the maximum count of plasma discharge will be decreased 8 per 5 seconds.
• The lowest limit for the maximum count of plasma discharge is about 700.
• The maximum count of plasma discharge will begin to increase gradually if the panel temperature falls to the specified
temperature.
High-temperature protection function 1
If a still picture is displayed for 3 minutes or more, the limit for the maximum count of plasma discharge will be gradually
decreased to minimize the effects of phosphor burn.
• This function is activated after detection if the displayed picture is still (the picture will be considered to be still if only the
mouse cursor is moved).
• The limit for the maximum count of plasma discharge will be decreased 8 per 5 seconds.
• The lowest limit for the maximum count of plasma discharge is about 700 (it takes about 15 minutes to reach the lowest limit,
although the required time varies depending on the displayed picture).
• The maximum count of plasma discharge will begin to increase gradually if the displayed picture is changed to animated
picture.
Note: How to decrease the brightness level in this function is the same as in high-temperature protection function 1.
Panel protection function 1 (protection against still picture)
If a particular load is applied to the SCAN IC, the limit for the
maximum count of plasma discharge will be gradually decreased.
Note: How to decrease the brightness level in this function is the
same as in high-temperature protection function 1.
Panel protection function 2 (SCAN IC protection)
A bright window, as shown in the figure on the right, on the screen
increases the heat of the panel. If such a pattern is recognized on
the screen, the limit for the maximum count of plasma discharge
will be gradually decreased.
Note: How to decrease the brightness level in this function is the
same as in high-temperature protection function 1.
Panel protection function 3
(protection against panel cracking)
If the panel temperature (TEMP1) reaches 65
°
C, the plasma-discharge count that is determined based on the input APL will
be decreased. In actual operation, the ABL adjustment value will be offset.
• This function is activated based on the TEMP1 temperature.
• The ABL adjustment value will be decreased by one step per 30 seconds.
• The ABL adjustment value will begin to increase gradually if the panel temperature falls to the specified temperature.
High-temperature protection function 2
Maxim
um count of plasma discharge
Detection example: Protection against panel cracking
Detection example: SCAN IC protection