Subject:
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ir reflectance sensors found !!!
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Fri, 31 Jul 1998 11:33:54 GMT
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Original-From:
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Jaron Paludanus <jaron@cybercomm(spamless).nl>
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Viewed:
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879 times
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Howdy,
When browsing through the catalog of CONRAD ELECTRONICS (www.conrad.de) I
found an IR reflectance sensor with build in logic to measure distances
between 10 and 80 cm. I requested the datasheets and they arrived today; I
am gonna order article number 185329! The datasheets describe in some
detail the measuring process with examples of different materials,
situations and conversion formulas. Allas no circuitry examples but they
suggest it is standard (?).
According to the specs, size, weight etc. it should be an ideal sensor for
a robot.
Since I have not much experience I hope to get all your help to get this
going.
I included some data, hoping to interest more people.
Hope to hear from you.
jaron
--------------------------------------------------------------
<here some of the datasheet, sorry; no scanner = no pics>
The sensor itself measures about 40mm x 14 mm x 16mm and uses four pins to
connect to the world. (Vin / GND / Vo / Vcc)
Operating Supply Voltage
Symbol Rating Unit
------ -------- -----
Vcc 4.4 to 7 V
Electro - Optical Characteristics (Ta=25 degrees C, Vcc=5V)
Parameter Symbol Conditions Min. Typ.
Max. Unit
---------------------------- ------- --------------- ------- -----
----- -----
Distance measuring range delta L - 10 -
80 cm
Output terminal voltage Voh at high level Vcc-0.3 -
- V
Vol at low level - -
0.3 V
Average supply current Icc during measuring - 10
- mA
Standby mode supply current Iccoff Vin=high(current=off) - 3
8 uA
Vin terminal current Ivin Vin=0V - -160
-270 uA
Measuring principal and features of this sensor
Principal of triangulation
Optical spot position on PSD shall be changed when reflective object is at
'A' point and at 'B' point.
By processing this optical spot position electrically, the position
(distance) of the reflective object on straight line can be detected.
Features of the GP2D02/05
* Compact high performance distance measuring sensor with build-in PDS,
Infrared LED and signal processing circuit.
* Little influence by collor and reflective ratio of the reflective object.
* High accurracy measuring by sequential position detection and mean
processing data output.
* GP2D02: 8 bit serial measured output which is possible to connect
directly with micro computer.
* GP2D05: 1 bit (high/low) measured output. The measuring range can be
adjustable as threshold level at any distance by adjusting the built-in
volume.
* Low current consumption at stand-by mode (Current consumption at stand-by
mode: TYP 3uA)
Input signal
Input should be current driving input in order to improve the measuring
accuracy.
Circuit Example
--------|
| Vin terminal
O-------------|
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| \
| \ | R 10k
| \| _______
sensor | /|----------|_____|----------O input
| / |
--------| /
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---
///
Concrete application example of the GP2D02
* Output conversion
The relation between the output of the GP2D02: "D" and the distance to the
reflective object can be shown in the following:
D=b/(L1+a)+C
However, actual deviation shall deviate mainly shifting the following
output curve (Distance characteristics) toward up and down direction.
This is caused by the position tolerance between the detecting device (PSD)
and the front lens in assembly
This deviation will be appeared as 'C' in (*1).
Since 'a' and 'b' can be assumed as almost constant value. actual relation
between "D" and "L" shall be shown in the following:
D=1560/L1+0.5)+C
* Output conversion method
As shown in (*2), the output of the GP2D02: "D" is in proportion to
1/(L1+0.5) (at L1=10 to 80cm).
The relation graph between output "D" of the sample which has output
characteristics shown in Fig.1 and 1/(L1+0.5) is shown in Fig.2.
By getting "C" for each sample using (*2) the distance to the reflective
object: "L1" can be calculated by output value "D".
...
the datasheet continues ...
...
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