Function Of Decreasing The Brightness Level; Limiting For The Maximum Number Of Sus Pulses; Abl Adjustment Value Offset; Relationship Between Input Apl And Number Of Sus Pulses - Pioneer PDP-5020FD Service Manual

5

[2] FUNCTION OF DECREASING THE BRIGHTNESS LEVEL

If the panel temperature becomes high or a video signal that requires activation of panel protection is input, the unit will
protect the panel by decreasing the brightness level.
* While a mask is being displayed, the panel protection function will not be activated.
Protection Function
Purpose
Name
High-temperature For protection of
protection function 1 parts (DCF)
High-temperature For reducing
protection function 2 heating in the unit
Panel protection For preventing
function 1 burn-in
Panel protection For protection of
function 2 SCAN ICs
Panel protection For protection
function 3 against panel
cracking

Limiting for the maximum number of SUS pulses

By gradually decreasing the limit for the maximum number of SUS pulses, the temperature of the panel will be lowered.
• The limit for the maximum number of SUS pulses will be decreased by 8 per 5 seconds.
• The lower limit for the maximum number of SUS pulses is about 700.
• The maximum number of SUS pulses will begin to increase gradually if the conditions that led to activation of the
protection function return to normal.

ABL adjustment value offset

By gradually offsetting the ABL adjustment value, the temperature of the
panel will be lowered. The number of SUS pulses, which is determined
based on the input APL (average picture level), will be decreased.
• The ABL adjustment value will be offset by one step per 30 seconds.
• The ABL adjustment value will be gradually restored if conditions that
let to activation of the protection function return to normal.
Limiting for the maximum number
of SUS pulses
2000
700
Fig. 1: Relationship between input APL and number of SUS pulses
5
6
Conditions
Panel temperature (TEMP1) Offsetting the ABL
reaches 65 ºC. adjustment value
Panel temperature (TEMP1) Limiting for the maximum
reaches 80 ºC. number of SUS pulses
A still image is displayed for Limiting for the maximum
3 minutes or more. number of SUS pulses
An image with which a particular Limiting for the maximum
load is applied to one SCAN IC number of SUS pulses
is displayed. (See Fig. 2)
An image with which the heat of Limiting for the maximum
part in the panel is increased is number of SUS pulses
displayed. (See Fig. 3)
Offsetting of the ABL adjustment value
The number of SUS pulses with regard
to the input APL will be decreased.
Input APL
PDP-5020FD
6
7
Protection Function
The picture will be considered to be still
if only the mouse cursor is moved.
Fig. 2: Detection example: SCAN IC protection
Fig. 3: Detection example: Protection against panel cracking
7
8
Remarks
81
8
A
B
C
D
E
F