Posted tagged ‘Sensors’

QTC

August 23, 2011

01-3D tablet-touch screen-force sensitive touch screen-quantum tunnelling composite

QTC is a composite made from micron-sized metallic filler particles (Silicone Rubber) mixed into an elastomeric matrix. Quantum tunnelling composite is a flexible polymer that exhibits extraordinary electrical properties. In its normal state it is a perfect insulator, but when compressed it becomes a more or less perfect conductor and able to pass very high currents.

01-QTC-Graph-resistance vs force - quantum tunnelling composite

History:

First produced in 1996, QTC is a composite material made from conductive filler particles combined with an elastomeric binder, typically silicone rubber. The unique method of combining these raw materials results in a composite which exhibits significantly different electrical properties when compared with any other electrically conductive material.

01-QTC pills-variable resistor-applications of QTC using pills-touch switches

Types of QTC:

1. Elastomeric (Material: Silicone Rubber) (The particle move close together)

2. Ink / Coating Solvent or Aqueous Polymer

3. Granular Sensors

Working of Quantum tunnelling composite:

01-quantum tunnelling composite-QTC-smart flexible polymer-silicone rubber-pressure switching-sensing-metal like conductor-variable inductance principle-QTC working-QTC operation

QTC usually comes in the form of pills or sheet. QTC pills are just tiny little pieces of the material. The sheets are composed of one layer of QTC, one layer of a conductive material, and a third layer of a plastic insulator. While QTC sheets switch quickly between high and low resistances, QTC pills are pressure sensitive variable resistors.

Application:

01-QTC touch Screen-pills-force or pressure sensors-quantum tunneling composite screen-pressure sensitive variable resistors

– Touch switches (sheet)
– Force/pressure sensors (pills)
– Motor speed control using force (pills)

Benefits:

  • QTC is a pressure/force sensing material. It can be easily integrated into existing products to enable force sensing opportunities and solutions.
  • Product surfaces can be incorporated, coated or impregnated with QTC to impart the properties of force sensing into or onto the host surface.
  • QTC material can be formed or moulded into virtually any size, thickness or shape, permitting redesign of product interfaces and providing improved ergonomics, aesthetics and user comfort.
  • QTC is an enabling technology which is simple and reliable to use.
  • QTC material is durable – it has no moving parts to wear out.
  • QTC material is mechanically strong.
  • QTC material can be made to withstand extreme temperatures limits.
  • QTC material is versatile, both electrically and physically e.g. Its range and sensitivity can be altered. QTC material is also intrinsically safe – the material is a contactless switch, ideal for sparkless operation.
  • QTC material can be directly interfaced to standard electronic and electrical devices.
  • QTC material and/or technology can be customized for customer requirements, applications and products.

PASSIVE LIGHT SENSOR

August 22, 2011

Rain sensor systems:

Opto electronic sensors are used in a reflective mode in rain sensor systems to detect the presence of water on the windshield so that the windshield wipers can be controlled automatically.

01-rain sensor-rain gauge-electro luminescent diodes-ambient light sensors-light sensor-LED-Light emitting diode

An LED emits light in such a way that when the windshield is dry almost the entire amount of light is reflected onto a light sensor. When the windshield is wet, the reflective behavior changes: the more water there is on the surface, the less light is reflected. In the new rain sensor, infrared light is used instead of conventional visible light. This means that the sensor can be mounted in the black area at the edge of the windshield and cannot be seen from outside.

Working Operation:

01-ambient light sensor-working principle-reflection of infrared light-electro luminescent diodes


An infrared beam is reflected off the outer windshield surface back to the infrared sensor array. When moisture strikes the windshield, the system detects a reflection to its infrared beam. Advanced analogue and digital signal processing determines the intensity of rain. The sensor communicates to the wiper control module, which switches on the wiper motor and controls the wipers automatically, according to the moisture intensity detected.


01-Rain sensor-auto dimming mirror-light sensor

Depending on the quantity of rain detected, the sensor controls the speed of the wiper system. In conjunction with electronically controlled wiper drive units, the wiping speed can be continuously adjusted in intermittent operation. In the event of splash water – as when overtaking a truck – the system switches immediately to the highest speed.

01-Rain sensor working principle-auto dimming mirror

The new rain sensor offers further options. For example, it can be used to close windows and sunroofs automatically if the vehicle is parked and it starts to rain. It can even be fitted with an additional light sensor to control the headlights – at night or at the entrance to a tunnel, the lights can be switched on without any intervention by the driver.

For Windshield wipers working operation Click this Link.

Light Sensors:

Automatic lighting of the headlights is controlled by a passive light sensor. It measures available light using a set of photo-electric cells.

01-light sensor-rain gauge-electro luminescent diodes-ambient light sensors-rain sensor-LED-Light emitting diode

The light sensor comprises three lenses that focus the light onto three photo-electric cells. This allowed “the luminous space” surrounding the vehicle into several zones through the directivity of each basic lens cell pair.

  • Lens 1: Measure total ambient light
  • Lens 2: Intersect Front source of light
  • Lens 3: Distinguish Road Condition (Like brighter sunny weather condition or Dark tunnel)

By comparing the information gathered by these three devices, the system computer determines the situation with which the vehicle is confronted and commands the headlights in consequence.