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[on:]

hey guys, i was wondering, if i want to take a non contact thermometer and feed the temperature vales which it displays on the built in lcd to my pc for storage, how can that be done?

[Reply #1 on:]

aim a webcam on it ?

You need to provide more details about the device used to give a tech answer. You might tap the signal at the sensor, or near the lcd both are possible, but it requires in both cases some serious reverse engineering.

[Reply #2 on:]

hmm that sounds incredibly complicated, the problem i see with the webcam is that picture taking may be very slow, especially since i want to use this device to make thermal area plots for a thermocam. what is the fastest image acquisuition rate i can get from a typical consumer webcam?

heres the basic concept:

-take two servos and assemble them to provide x-y control
-connect thermometer and webcom to servos, placing the webcam so that it centered at the same point the laser from the thermometer is aimed at.
-place servos at 0 displacement(looking dead centre) and take picture with cam.
-based on the FOV of the camera, change servo angle to aim where the top right corner of the first image would have been.
-*turn on thermometer for say 30ms by replacing the physical trigger with a digital one connected to the board, recording output value from lcd to the pc(along with servo angle) 2-3 times during this period.
-move servo in raster motion repeating this process to obtain a 'grid' of thermal values.
-use graphical postprocessing to shade the grid with desired colors based on temperature value at each cell in the grid
-overlay the original image with the thermal grid(for eg with photoshop) for a cheap thermo-map.

i suppose if i am using a webcam with a fast enough image capture rate i can have it take images of the lcd at the rate stated in the * step, then record the values after by examining them in a slideshow. I also guess i could program analytical software to then auto convert the values using image recognition, but this again seems like a bit of a task.

where can i learn about reverse engineering an lcd?

[Reply #3 on:]

check - http://www.cheap-thermocam.tk/ - for inspiration

where can i learn about reverse engineering an lcd?

text only or a graphical LCD?

Course LCD hacking:
Chapter 1: find the type and typenumber, you must open the device, and some LCD's just don't have a name and number => EXIT

Chapter 2: google the datasheet, relative easy

Chapter 3: identify the communication lines, can be harder

Chapter 4: sniff the data from them, Can it be soldered? or otherwise? What protocol is used?

Chapter 5: interpret them, can also be hard but mostly ASCII characters are used, what is the data, what is overhead?.

Chapter 6: process the data, relative easy if all other succeeded

Chapter 7: answers to the exercises, 

Thats about the outline, can take one hour, can take 3 weeks. 
The good part is that hacking a sensor is quite similar.

Rob

[Reply #4 on:]

hey rob, thanks for the info. i actually went to that site first, thats where i got the idea. that system will actually work just fine for my purposes, but the sensor he uses has become short supplied and relatively expensive(about 70 bucks). in comparison, a handheld therm wud run be about 40 bucks, and i would at least have the fallback of being able to just take measurements by hand if all else fails(though my data set would probably be a lot smaller due to laziness =D)

[Reply #5 on:]

What do you want to measure?

With a DS18B20 you can measure (with contact) temperature quite well,  - http://www.sparkfun.com/products/245 - $5
or Infrared Thermometer - MLX90614 - http://www.sparkfun.com/products/9570 -  $20