Sanyo EP92H User's Manual | Page 17

Sanyo Cell Phone User's Manual - EP92H.
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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 (ISC, typical)

Dark current (VR = 50 mV) MAX.

    AM-30-26

    1.2    A *1

    10 pA

2.1 

× 2.0 mm2 

(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.

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