TA1204AF Datasheet, PDF (13/25 Pages) Toshiba Semiconductor – γ CORRECTION IC FOR LCD TV

TA1204AF
METHOD OF MEASUREMENT
Note 1:
Note 2:
Note 3:
Note 4:
Image signal input dynamic range
• Test condition 2 (direct-coupling mode)
• Input : G In1 / G In2
Test signal 1
For input A, measure the peak levels at input pins 32 {34, 36} immediately before the top / down
clipping of the output signals of output pins 21 {19, 14}, while adjusting VR34 and changing the
pedestal levels at the end of the input pin. Specify the difference between the upper and lower
measurement values as the dynamic range to be obtained.
For input B, change SW2B from a to b, adjust VR40, and take the same measurements for input pins
38 {40, 42}.
Inter-channel crosstalk 1
• Test condition 5 (CP mode, fixed polarity)
• Input : X In1 / X In2
Test No. 2
Measurement frequency 1MHz
• Other input pins
(Y In1 · Z In1 / Y In2 · Z In2) : short to GND
Change SW27 from a to b as before, and adjust VR27 so there is no difference between the γ0 and
black levels in the output waveform at pin 19.
For input A, input it to the X-axis (pin X In1) and measure the amplitude values of the 1MHz
components at output pins 21, 19, and 14. Short to GND the other input pins (Y In1 / Z In1).
Crosstalk from the X-axis to the Y-axis = (amplitude value of the Y-axis output) /
(amplitude value of the X-axis output)
Crosstalk from the X-axis to the Z-axis = (amplitude value of the Z-axis output) /
(amplitude value of the X-axis output)
Change the combination of X, Y, and Z among B (output pin 21), G (output pin 19), and R (output pin
14), and repeat the same measurement. For the B input, change SW2B from a to b, set the input pin
at BINX, short to GND the other input pins (Y In2 / Z In2), and measure as for input A.
Switched SW crosstalk
• Test condition 5 (CP mode, fixed polarity)
• Input : X In1 (X In2 = short to GND)
/ X In2 (X In1 = short to GND)
Test signal 2
Measurement frequency 1MHz
Change SW27 from a to b as before, adjust VR27 so there is no difference between the γ0 level and
the black level in the output waveform of pin 19, input it to the channel A X-axis (pin X In1), switch
SW2B from a to b, and measure the amplitude value of the 1MHz component of the X-axis output
pins (pin 21 when X = B, pin 19 when X = G, and pin 14 when X = R) before and after switching.
Crosstalk from input A to input B =
(amplitude value when SW = b) /
(amplitude value when SW = a)
Change the input pin to channel B (pin X In2) and repeat the same measurement.
Crosstalk from input B to input A =
(amplitude value when SW = a) /
(amplitude value when SW = b)
Repeat this measurement replacing B, G, and R as the X-axis.
Typical amplitude for signal outputs, inter-axis amplitude deviation, and polarity difference
• Test condition 4 (CP mode)
• Input : X In1
Test signal 3
Input signals (0.7Vp-p) including black and white levels at input A (X In1).
Measure the amplitudes between the black and white waveform levels at output pins (pin 21 when X
= B, pin 19 when X = G, and pin 14 when X = R) for positive and negative polarities.
Repeat this measurement replacing B, G, and R as the X-axis.
2001-02-07 13/25