Experiments with lcd

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Experiments with LCD screens

Release status: Just started

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Description
Experiments with LCD and UV.
License
GPL
Author
Contributors
Based-on
Categories
CAD Models
External Link





Experiments with LCD screens

These experiments are to look at the possibility of using LCD screens as UV masks for Vat Grown RepRap 3d printing or Automated Circuitry Making PCB creation.

If this is of interest to you, Please join in and add to this page.

Two years ago a cheap digital photo frame was purchased to look into the viability of it being used as a UV mask for curing resins layer by layer, the consensus at that time was that the UV light would damage the LCD or that the LCD would not pass UV, therefore the project was put on the back burner, but recent interest in this has prompted revived interest, an old LCD monitor has also been acquired and will be tested.



Measurement

An old reflectance meter to measure the amount of light passing through the panel, this has light sensitive material which generates a voltage (millivolts) proportional to the amount of light, this can not measure wavelength but should give representative values?, it gives readings for white light as well as UV light.

Old reflectance meter
Underside showing light sensitive material


Quinine apparently is UV sensitive, Tonic water could be used as an indicator of the amount of UV passing through the LCD.

Effect of UV on tonic water, image source Wikipedia

















Photoframe front
Photoframe rear
Diplaying image
bezel removed
Display panel folded back to reveal circuit, usb and media slots
LCD and backlight separated
Backlight held behind LCD, be careful of the HT
Backlight has convenient plug for removal
Luxeon LED with diffuser used as backlight










The Photo frame has USB and media card slots, a USB stick with images on the root will be displayed in automatic mode, the delay between images is also settable, the stripdown took a few minutes only, and does not involve destruction of any components. The materials used for manufacture in LCD panels may vary, therefore the transmission of UV may vary for different panels?.


Experiment 1... Using a suitable UV light source, measurements of light output with and without the screen in place to ascertain if UV light will pass and at what ratio.

3 sources of UV are available to the author, UV led, UV cold cathode (bug killer), UV pcb developer. (try and find wavelengths and power output of each)



Experiment 2... Long term test to observe effects of UV on LCD, dependant on experiment 1.



Repeat experiment 1 and 2 with monitor LCD





LCD Monitor An old computer monitor has been dismantled to extract the LCD screen, the monitor was built to a high standard, with metal support frame to guard against twist and breakage of the LCD panel,

An old computer monitor
Bezel removed
Showing metal support frame and drive electronics
Backlight and LCD panel removed
LCD panel removed from backlight
A single LED as illumination





Very old Astrobeam projector

An old computer monitor
An old computer monitor
An old computer monitor
An old computer monitor


The Astrobeam is built to a very high standard and probably cost a great deal when new, the bulb adjustment is on a ball bearing slide, and the metalwork is mainly thick aluminium, it has 2 Fresnel lenses, one before the lcd panel and one behind it. It is possible that LCD screens used for projection were made different from LCD for display ??????.