Publication

An LCD Tachistoscope With Sub-Millisecond Precision

2013
Posters

Abstract

Tachistoscopes allow brief visual stimulation delivery, crucial for experiments where subliminal presentation is required. Up to now, tachistoscopes have shortcomings regarding timing accuracy, reliability, and flexibility of use. Here, we present a new and inexpensive 2-channel tachistoscope which allows for exposure durations in the sub-millisecond range with an extremely high timing accuracy. The tachistoscope consists of two standard liquid-crystal display (LCD) monitors of the light-emitting diode (LED) backlight type, a semipermeable mirror, a mounting rack, and an experimental personal computer (PC). The monitors have been modified to provide external access to the LED backlights which are controlled by the PC via the standard parallel port. Photodiode measurements confirm reliable operation of the tachistoscope and reveal switching times of 3 microseconds.

Official source

https://infoscience.epfl.ch/entities/publication/142ce209-e586-439e-9437-aad4a51b1811

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2013
Posters

Abstract

Official source

https://infoscience.epfl.ch/entities/publication/142ce209-e586-439e-9437-aad4a51b1811

About this result

Related concepts (31)

Backlight

A backlight is a form of illumination used in liquid-crystal displays (LCDs). As LCDs do not produce light by themselves—unlike, for example, cathode ray tube (CRT), plasma (PDP) or OLED displays—they need illumination (ambient light or a special light source) to produce a visible image. Backlights illuminate the LCD from the side or back of the display panel, unlike frontlights, which are placed in front of the LCD.

Liquid-crystal display

A liquid-crystal display (LCD) is a flat-panel display or other electronically modulated optical device that uses the light-modulating properties of liquid crystals combined with polarizers. Liquid crystals do not emit light directly but instead use a backlight or reflector to produce images in color or monochrome. LCDs are available to display arbitrary images (as in a general-purpose computer display) or fixed images with low information content, which can be displayed or hidden: preset words, digits, and seven-segment displays (as in a digital clock) are all examples of devices with these displays.

Light-emitting diode

A light-emitting diode (LED) is a semiconductor device that emits light when current flows through it. Electrons in the semiconductor recombine with electron holes, releasing energy in the form of photons. The color of the light (corresponding to the energy of the photons) is determined by the energy required for electrons to cross the band gap of the semiconductor. White light is obtained by using multiple semiconductors or a layer of light-emitting phosphor on the semiconductor device.