These devices are a type of photodiode that can detect light with about the same sensitivity as the human eye. Since these
devices flexibly support a wide range of end product designs and sizes, they can be used to control the LCD backlight and
button lamps in cell phones to implement power saving automatic brightness adjustment
33
32
Achieving Low Power and Superb Viewability
Amorphous Optical Sensors
●
Increased operating time for portable electronic
equipment due to reduced power consumption!
●
LCD backlight level automatically adjusted to just the
right level for viewing according to the ambient
illumination level
These devices are a type of photodiode that can detect the presence/absence of ambient light, or the intensity of ambient light.
Wavelength [nm]
Illumination [Lux]
1
400
500
600
700
800
900
1000
0.5
Relativ
e sensitivity
Visible wavelength amorphous optical sensor
Human visual sensitivity
Single-crystal silicon optical sensors
2.0
[AM-30-26]
2.1
0.84
0.88
1.2
1.E-10
1.E-09
1.E-08
1.E-07
1.E-06
1.E-05
1.E-04
1.E-03
1
10
100
1,000
10,000 100,000
Isc(A)
Measured at FL
(for color illuminator): 1 to 10 kLx
: 10 to 10k Lx
at SS (Solar Simulator)
[AM-30-26]
Bright environments
Dark environments
Bright environments
Dark environments
LCD backlight ON
LCD backlight ON
LCD backlight OFF
Button lamps ON
95 to 110mA
Button lamps OFF
55 to 70mA
Button lamps OFF
5 to 20mA
About 300Lx
About 3Lx
Unnecessary power
consumption occurs
Unnecessary power
consumption occurs
LCD backlight ON
LCD backlight ON
LCD backlight ON
Button lamps ON
95 to 110mA
Button lamps ON
95 to 110mA
Button lamps ON
95 to 110mA
Bright environments
Dark environments
LCD backlight
Button lamps
Automatic brightness adjustment
ON
OFF
Like amorphous silicon solar cells, amorphous optical
sensor use the photovoltaic effect in semiconductors.
When light hits a semiconductor, electrons and holes
are created, the electrons diffuse in the n-type
semiconductor, and the holes diffuse in the p-type
semiconductor. As a result, a current will flow when the
two semiconductor types are connected externally.
The current output from the amorphous optical sensor is
converted to a voltage, and signal processing is applied to that
voltage.
Normally, an operational amplifier is used for linear amplification.
The amorphous optical sensor is connected to a resistor and the
voltage is input directly to an A/D converter for discrimination.
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
Transparent electrode
p
i
n
Metallic electrode
Light
Electron
Electron hole
(+) Anode
(-) Cathode
*
1 : at 1000Lux, Fluorescent Light for color illuminator
Type No.
External dimensions (mm)
Short-circuit current (I
SC
, typical)
Dark current (V
R
= 50 mV) MAX.
AM-30-26
1.2 A
*
1
10 pA
2.1
×
2.0 mm
2
(glass thickness: 0.4 mm)
3V
Amorphous
Optical Sensor
(AM-30-26)
A
A/D converter
R
C
Amorphous
Optical Sensor
(AM-30-26)
A/D converter
With an operational amplifier
Without an operational amplifier
Flexible pattern geometries and sizes
These devices support designs with sizes and
shapes that correspond to the target application.
The output current is proportional
to the illumination
Since the output current changes proportionally to
the light striking the sensor, these devices provide
precise detection.
High sensitivity in the visible region
The human eye is sensitive to light with
wavelengths from about 400 nm to about 700 nm.
Since these amorphous optical sensors have
sensitivity to essentially the same wavelengths,
they provide sensing that is close to that of the
human eye.
Contact your SANYO sales representative for details on these products
Amorphous Silicon Solar Cells
Amorphous Optical Sensors
Amorphous Optical Sensor Application Examples
Amorphous Optical Sensor Structure
Amorphous Optical Sensor Circuit Examples
Amorphous Optical Sensor Product Lineup
Automatic adjustment of LCD backlight and operating panel buttons
Cell phone with built-in optical sensor
Cell phone without built-in optical sensor
Amorphous optical sensor spectral sensitivity
Illumination-dependent characteristics of ISC
Amorphous optical sensor pattern examples
These sensors can be used to sense the ambient
illumination level and automatically turn off these lamps in
bright operating environments. This reduces unnecessary
power consumption and creates LCD screen display that is
easy to see whatever the ambient lighting.
Summary of Contents for Easy Radio IC LV24000 Series
Page 1: ... 06 04 Cell Phone Devices ...
