 The history of automotive windshields is as interesting as the automobile itself. The elementary form of what we call as windshields on modern autos dates back to early twentieth century. Windshields were sold as optional equipment to motorists who needed something a little more dashing than goggles. Soon came closed cars, buses and trucks. The demand for vehicle glass rose sharply, and has been climbing ever since. By 1929, 9 out of 10 cars were equipped with glass all around, to provide protection from wind, rain, mud splashes, road dust, and flying debris. Driving now became an all-weather activity. In 1924 the process for plate glass was changed from the "batch" method to a continuous ribbon method making the production of glass much more efficient, reliable and affordable. Four years later PPG introduced a process to mass-produce sheet glass which further improved quality and availability. These advances significantly improved the vision through the windshields, eliminating much of the distortion that had previously existed and made the product affordable enough to be widely used in the automobile. The innovations in the glass industry with improved optics and affordable costs, made the widespread use of glass windows in cars practical.
Safety glass in the form of laminated windshields was introduced in 1927. This would include a layer of film between two layers of thin glass. While lamination, in today's times, would mean a multilayer unit consisting of a thin plastic layer (currently polyvinyl butryal or PVB) layered between two sheets of glass, curved windshields appeared in 1934 and ushered an era of windshields that curved four ways – not only at the sides but at the top and bottom as well. Curved rear windows have come to present a good deal of styling freedom. However, beyond styling freedom, a windshield of today, or the side (window) glasses on contemporary automobiles are fabricated such that they have holes drilled in them to help them anchor to the sliding mechanism. While the rear and side glass were often tempered until recent times, a process which gives it strength against shocks to a great extent, the front windshield is subject to constant improvement and research. Laminated glass to say the least, has taken over.
Acting as a component of body that offers added rigidity, glass on modern cars is often laminated all-around. From a point of view of safety this translates into laminated glass being more difficult to shatter than tempered auto glass. Laminated glass can also help reduce the incidence of passenger ejection – a possible result of impact that can make the occupant three times more likely to be killed than if he or she had stayed inside the vehicle. The strength of the plastic can allow windows and windshields to stretch and yield, serving as a “safety net” to keep passengers inside. Furthermore, an extra layer in laminated glass offers additional sound protection. In developed markets like US, the use of laminated glass accounts to 100%. Interestingly, plastics are increasingly used as adhesives to bond the windshield directly to the car, enhancing vehicle structure and helping to prevent the windshield from popping out in an accident. Plastic windshield adhesive has effectively halved windshield bond separation and occupant ejection through the windshield portal, saving numerous lives every year.
 Automotive laminated glass also comes with infrared coatings and ultraviolet protection options. Not only do these technological developments keep the harmful sun's rays from heating or damaging the car's interior – plastic parts especially, they also help to protect the passengers from the harmful UV rays that contribute to skin cancer.
New developments in the area of communication and infotainment involve the automotive glass as well. From antennas and defrosters to speedometers, many types of laminated glass include the latest technologies right in the interlayer. While these types of benefits might not add to driver safety, they do add an appeal that increases car value and satisfaction. Some modern automobiles have come to posses a technology called “heads up display”. The “heads up display” technology displays data and control settings via projection onto the inside of the windshield.
An important element of this technology are a combination of different types of light and temperature sensors to give drivers what can be equated to night vision. The new windshield technology enhances objects near the road such as mailboxes, telephone poles, people and animals by outlining them in a lighted silhouette. Efforts are on to create a full-size HUD that will cover the whole windshield to better integrate with the driver’s natural field of view. For full-size HUD operation, the whole windshield is coated with a series of transparent phosphors, which emit visible light when excited by a light beam from a compact laser, transforming into a large area transparent display. In pursuing to make driving safer, General Motors, which has been at the forefront of full-size HUD development, wired the full-screen HUD to a series of top-of-the-line sensors like night vision systems, global positioning navigation and camera-based sensor technologies. Interestingly, the system will also introduce a new concept in GPS navigation, allowing the driver to actually see the desired point-of-interest, such as a building, thanks to the system’s feature that highlights the aforementioned object on the screen in real time.
 In what is considered as a giant leap into future, an Italian design house recently unveiled a concept car without mechanical wipers. The concept car uses nanotechnology to keep its windshield clean. The windshield is made of a special glass with four high-tech layers that change the characteristics of glass at the molecular level.
The outermost layer is based on titanium dioxide and filters the sun and waterproofs the windshield. The second layer of glass is actually made up of microscopic dust pushing dirt on the sides of the glass. The third layer contains sensors that sense the dirtiness and wetness of the windshield. Like an LCD display, the fourth layer conducts electricity, needed to power this complex multilayer windshield.
With technological innovations like a full-size HUD windshield or a wiperless windshield around the corner, automotive glass or windshield, which was once an optional fitment, will soon turn out be a major contributor of safety, reliability and functionality.
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