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News Release from: Sharp Microelectronics Europe | Subject: Opto devices for automotive sector
Edited by the Electronicstalk Editorial
Team on 17 November 2006
Opto advances free automotive dash
design
The ergonomics of vehicle passenger compartments are undergoing huge changes, thanks to innovations in the electronics sector.
The ergonomics of vehicle passenger compartments are undergoing huge changes, thanks to innovations in the electronics sector Until recently, mechanical rotary and flip switches were sufficient to operate applications such as ventilation, display lighting and radio
This article was originally published on Electronicstalk on 16 May 2003 at 8.00am (UK)
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The increasing tendency for electrical and electronic applications to be installed in vehicles means that the large number of controls has resulted in a confusing range of switches.
This trend is not good for road safety, as the large number of switches is making it more difficult to operate a vehicle and distracting drivers, slowing down their responses.
Three promising trends for increasing road safety and optimising ergonomics are therefore now being seen in the design of vehicle interior electronics and their controls: the introduction of TFT-LCDs as central navigation and infotainment displays; the consolidation of control of new car infotainment functions in particular in a multifunction switch called a centre switch; and combining flip switches into combined press and rotary switches.
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The new generation of switches must therefore not just be designed to meet the requirements of the vehicle industry in terms of heat resistance and mechanical stability, as they now have to fulfil many more functions and be easy and safe to use without significantly distracting the driver.
Sharp produces a number of optoelectronic components that give development engineers greater freedom in the ergonomic design of switches and control units in vehicle interiors.
The introduction of central information displays (CID) is one way in which car manufacturers can increase cockpit clarity.
The correct and, in particular, automatic adjustment of the brightness of the central information display depends very much on the ambient light conditions.
In bright sunlight, the display needs to shine more brightly to be easily legible, while the display should be dimmed in dark light conditions.
The changeover between light and dark ambient conditions sometimes occurs very quickly during driving, often when a vehicle drives into a tunnel or underground car park or because of changing weather conditions, for example.
The automatic control of display brightness is certainly a function that is relevant for safety.
If it doesn't occur during night driving, for example, the big difference in brightness between the display and the ambient light conditions may affect the driver's ability to see.
Distracting reflections in the windscreen are only one consequence.
By looking at an overbright display, a driver is dazzled as if by a torch.
This will prevent the driver from seeing what is going on outside correctly, increasing the risk of accidents.
Taking the eye, the naturally perfect sensor, as its model, Sharp has developed innovative OPIC GA1A0S100WP and GA1A1S200WP brightness sensors for optimal automatic control of the background lighting of LCDs in vehicles.
Sharp sensors are characterised by the fact that they reproduce the way in which the human eye perceives brightness almost exactly.
This means that the sensors mainly react in the visible light range with wavelengths of between about 450 and 650nm.
In addition, an integrated temperature compensation system ensures that the sensors behave consistently over the entire range of temperatures relevant for use in automotive applications, from -40 to +85C.
Another advantage of Sharp sensors is their quick reaction time of up to 25us.
The display background lighting can therefore be readjusted accurately, efficiently and without delay as soon as there is a change in the ambient light conditions, unlike traditional photodiodes, which are affected by a much wider range of wavelengths and ambient temperatures.
They are therefore not suitable for the accurate control of display brightness.
Accurately adjusting display brightness to the ambient conditions also has the advantage of minimising electricity consumption and therefore also actively helping to save fuel, which is something that is dear to the heart of any car driver.
Unlike mechanical rotary and flip switches, the multifunctional centre switches used in modern vehicles need to permit a much higher numbers of switch positions.
Sharp photointerrupters make it possible to separate the mechanical and electrical designs of switches.
This increases flexibility for development purposes, since the mechanical properties of the switch no longer have a significant influence on the way that operation feels to the operator.
Photointerrupters are used as optical barriers that initiate the switching process when interrupted.
Their very small sise, with a side length of only a few millimetres, means that Sharp photointerrupters can be integrated without difficulty in any kind of switch.
A typical centre switch has several interrupters, which cover both linear (up-down, left-right, in-out) and rotary movements.
Breaking down the 360-degree rotary movement into up to 400 steps is easily sufficient for current automotive applications.
A further advantage of the electromechanical disconnection is long life, as the contactless switching process means no wear.
Sharp photointerrupters are therefore a cost-effective, maintenance-free alternative to magnetic switches, for example.
There are many possible uses of distance meters in a vehicle passenger compartment.
They can be used to operate applications in cars without contact, which is especially convenient when the switch is not visible.
The interior lighting may, for example, be turned off simply by means of a hand movement close to the switch, without having to feel for the switch in the dark.
Sensors can also be useful for setting the seat position, by activating the central information display at the time when the hand is close to the seat levers, which are often positioned where it is difficult to see them, in order to show which seat adjustment lever the hand is in contact with.
It is normally difficult to distinguish between the levers under the seat.
They can also be used to control the air conditioning system.
Distance meters in the car ceiling can determine which seats are occupied and precisely adjust the cold air requirement and air conditioning system output accordingly.
Drivers who usually drive alone will then benefit from reduced petrol consumption.
Sharp sensors are also very reliable.
Unlike traditional IR sensors, which determine distance on the basis of the strength of a reflected IR beam, Sharp technology is based on the rules of trigonometry.
The sensors measure the distance to an object on the basis of the angle from which the reflected beam reaches the detector.
Distance is therefore measured completely independently of the surface condition of the reflecting surface.
The sensors therefore react completely independently of the clothing, hair or skin colour of a vehicle's occupants or the colour of the car interior and reliably trigger the appropriate applications.
Depending on the application and distance measuring sensor used, automotive distance meters may detect objects at distances from a few millimetres to 80cm away and have a very compact design, with casing dimensions of 20 x 10 x 7mm.
All Sharp optoelectronic components for automotive applications meet the appropriate quality and environmental standards.
They are designed for an operating temperature of -40 to +85C.
The first examples of the new generation of automotive sensors are available immediately from Sharp Microelectronics and European distributors.
Series production is planned for the first quarter of 2007.
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