Konica Minolta CA-100PLUS, Instruction Manual

Page: 102 / 125

100
Measuring Principle
1. Measuring Principle
This instrument uses sensors of a spectral sensitivity similar to the CIE 1931 color-matching function (–
–
x
2
λ , – y λ , – z λ )
to measure RGB emission energy of a color display, and displays the results in xyLv, T, ∆ uvLv, u’v’Lv or XYZ
values.
Measurement is performed in the following sequence.
1 RGB emission energy of the color display is acquired through the measuring probe’s receptor, and then
converted to a voltage by the photoelectric conversion section. (Outputs: X
2
, Y, Z)
2 The temperature of the probe is detected by the temperature detection section. (Output: T)
3
The outputs (X
2
, Y and Z of
1
) from the photoelectric conversion section and the output (T of
2
) from
the temperature detection section are digitized in the A/D conversion section. A/D conversion is per-
formed simultaneously within the measurement time according to SYNC mode.
4 The digitized values (counts) are sent to the instrument’s CPU, where they are calculated according to the
measurement mode, SYNC mode and correction factor (user calibration), which have been set using
keys and switches.
5
The processing results are then displayed in the display sections, and output to a PC via RS-232C or USB.
Chromaticity coordinates (x, y) for xyLv (CIE 1931 color space) are obtained by the following formula.
X, Y and Z in the formula are tristimulus values
(X = X
1
+ X
2
= 0.1672Z + X
2
).
x =
X
X + Y + Z
y =
Y
X + Y + Z
Fig. 1 Instrument’s Spectral Sensitivity
Relative sensitivity
Wavelength (nm)
Instrument’s spectral sensitivity
CIE 1931 color-matching function
Measuring probe
Photoelectric
conversion section
Temperature
detection section
Main body
Probe connector [P1]
A/D
conver-
sion
section
USB
port
Fig. 2 Measurement Block Diagram
Photoelectric
conversion section
Photoelectric
conversion section
C P U
Display
section
VSYNC
connector
RS-232C
connector
USB
driver
RS-232C
driver
SRAM
FROM
PIO
KEY
Multi-point expansion
board connector
Vertical synchronizing signal input