GP2W0110YPS Datasheet, PDF (12/14 Pages) Sharp Electrionic Components – Low Power Infrared Transceiver

GP2W0110YPS/GP2W0114YPS
Low Power Infrared Transceiver
Product Packaging
Many products that use infrared communication
locate their reception component behind dark plastic.
This often fits in with the overall design and coloring
of the product, and has an intentional design purpose
as well.
The photodiode that is used in optical receivers is
sensitive to a variety of light wavelengths, not only the
wavelength intended for reception. Visible light has
many component factors and sources in a room. The
dark plastic used in product faceplates can be formu-
lated to act as a highpass filter, reducing the amount of
visible light and other wavelengths landing on the pho-
todiode and raising the internal noise currents.
The reduction of unwanted wavelengths provides for
a quieter and more sensitive receiver. The wavelength
used for IrDA Data communications is 880 nm. The char-
acteristic of any plastic used in a final product should
keep this in mind and not attenuate this wavelength.
Constructing an Optical Highpass Filter
A simple material for test purposes is to obtain a roll
of 100 ASA color film. Pull the film all of the way out of
the can and expose it to outdoor light for about 5 sec-
onds. Have the film developed, but first inform the per-
son operating the developer what you are doing so that
your intent is understood, and the material is processed
correctly. Otherwise you may be informed that the roll
has been overexposed and the material was therefore
discarded as unusable. The resulting developed nega-
tive stock should be dark and difficult to see through.
Using one or more layers will provide a variable attenu-
ation filter that you can tailor for experimental purposes.
Other light sources may produce different results.
The graph in Figure 16 was produced by exposing the
film to a ‘cool white’ fluorescent lamp for five seconds.
The filter transmission data is excerpted from an article
in Electronic Design, December 2, 1996, written by
David A. Johnson. The response of the material is fairly
steep near 830 nm, and has reasonable pass charac-
teristics above 880 nm.
Figure 16 shows the basic characteristic of the high-
pass filter. The exact position of the slope and increas-
ing response will depend on the material selected and
the light used to expose it. The intent is to supress vis-
ible light, and neighboring wavelengths, and pass the
desired 880 nm.
Other glass and plastic filters are available, and
many vendors carry plastic materials that may be cut,
bent or molded. The key to selecting a plastics vendor
is to ask them about the wavelength characteristics of
their materials. The more they know, the more likely
they will be to help you in a knowledgeable manner
when working on both the industrial design and wave-
length pass characteristics of your IR window.
100
90
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60
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10
0
300
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1,000
1,100
WAVELENGTH IN NM
Figure 16. Optical Highpass Filter
GP2W0110YPS-13
12
IrDA Technical Information