PH Origins: Auto-dimming mirrors


Entrepreneur Fred Bauer was making waves. He studied at the Michigan State University, graduating with a major in electrical engineering and a minor in business, and then launched his first company in 1967 - when he was just 23 years old.

Like any good entrepreneur, Bauer had identified the need for a product that he was well positioned to develop and supply. At the time, his father ran a furnace business and Bauer had seen the problems posed when trying to accurately monitor and regulate the combustion inside the furnaces.

Typically, the burner controls for the furnaces relied on heavy, complicated and expensive relay and motor systems that were prone to problems - resulting in erratic burner operation and improper furnace behaviour.

He subsequently designed his own electronic control systems which were more compact, reliable and accurate. Because of their improved circuitry and smaller size and weight, they could also be quickly adapted to a wider range of furnaces.

These new burner controls were put into production in 1967, by his freshly founded company called Simicon Corporation, and proved a great success. By 1971 Simicon employed some 90 people and was reporting sales of $1.8 million. It soon popped up on the radar of much larger businesses operating in the same sector and, in 1972, was bought out by Robertshaw Controls - which produced control systems for both buildings and standalone hardware.

Bauer would work for Robertshaw for several years before once again heading out on his own and setting his sights on a new product: smoke alarms. America was experiencing huge problems with fire in the 1970s, with one prominent report stating that 12,000 civilians were being killed in destructive fires each year - and tens of thousands were also being injured. The financial cost of these fires was significant, too, totalling some $11 billion a year.

There were a plethora of causes, including building design, material use and a lack of warning systems. Family homes accounted for some 80 per cent of fire-related fatalities and it was mobile homes, in particular, that were highlighted as being most hazardous. They contained lots of flammable material, had no fire safety requirements and were difficult to get out of in an emergency.

An act signed by President Johnson in 1968, which resulted in a commission being formed to study the nation's fire problems, led to a dramatic report entitled 'America Burning' in 1973. This report brought about several changes, including the promotion of smoke alarm installation - which would ultimately become a requirement in family homes in 1976.


In order to meet the rising demand, and to help develop better fire detection systems, Bauer helped found a new Michigan-based company called Gentex in 1974. It produced smoke detectors, aimed primarily at mobile homes, and came up with the world's first dual-sensor photoelectric smoke detector - the design for which was patented by engineer Jeffrey Franks.

Photoelectric smoke detectors, which had been invented in 1972, featured an internal light source and sensor set-up; when smoke entered the detector, the change in the amount of light transmitted from source to sensor would trigger the alarm.

These alarms were good at responding to the early initial smouldering stages of a fire and weren't as prone to nuisance alarms as ionizing detectors, which could be easily triggered by steam or light smoke from cooking. However, these photoelectric detectors relied on one bulb for a light source - so if the bulb failed then the detector would become useless.

They also often required complicated focusing assemblies and couldn't cope with changes in light output that came about as a result of an ageing light source or voltage and temperature-induced fluctuations. These early detectors, as a result, were often heavy, complicated, expensive and prone to false alarms.

Frank's improved design dealt with many of these issues, proving more reliable and quicker to act, but Gentex seemingly struggled to make any notable dent in the market - and, in the late 1970s, it was perilously close to shutting up shop.

What happened next isn't entirely clear but, reputedly, Bauer had established a design partnership called the Integrity Design Company that ran alongside Gentex - and, in fact, IDC itself may have indeed been the source of the photoelectric set-ups used in the smoke detectors.

IDC then appears to have been approached by, or engaged with, local automotive supplier Donnelly Corporation. Donnelly was a vast manufacturer of glass, mirrors, door handles and window hardware and was looking for a new product to add to its line-up. Bauer knew that OEMs were seeking ways to combat rear-view glare and, in particular, IDC/Gentex's photoelectric expertise could be used to help the company develop an auto-dimming mirror.

The concept of a light-sensitive rear-view mirror was not a new one, by a long stretch - with automatically dimming mirrors being offered as early as 1959. Chrysler, for example, offered the 'Mirror-Matic' which used a photocell-triggered electromagnet to tilt the prismatic rear-view mirror, helping cut glare and improving the driver's night vision.


None had been commercially successful, though, and increasing demands for safer motoring and technological advances had refloated interest in the devices. Consequently, Donnelly reportedly funded IDC to the tune of some $620,000 in order to hasten the development of the automatic day/night mirror.

Gentex, which was strapped for cash and clamouring for options, then announced that it was going to market the auto-dimming mirrors - snatching back the attention of many investors. The company went public in 1981, granting it access to a substantial amount of funding, which it used to buy the rights for the auto-dimming mirror system from IDC. The cash injection also allowed it to acquire the hardware required to produce the mirrors en masse.

The lines began running in 1982 and, by 1984, some 70,000 units had been shipped to the likes of General Motors and Ford - and sales continued to climb. By 1991, a total of 1.1 million of Gentex's mirrors had been sold.

One factor that prompted the surge in adoption was that many studies revealed that numerous drivers simply didn't bother using the anti-glare setting on their rear-view mirrors. As was the case with many automotive safety issues, automation was one of the few ways that the problem could be convincingly tackled without relying on the driver.

Gentex's auto-dimming mirrors were not without fault, though. The mechanisms could be noisy in operation, distracting the driver, and they could only offer fixed day and night positions. In some conditions, consequently, the view presented would be too dim or too bright.

Harlan Byker, and his father Gary Byker - scientists from Battelle Laboratories - had a solution to the problem. They were experts in the fields of thermochromics and electrochromics, which focused on substances which would change colour when heat or current was applied to them. Harlan Byker approached Gentex and claimed that he could use the electrochromic technology to counter the issues with the mechanical mirrors - by using an electrochromic system to remove the need for the mechanical system and also enable a variable range of accurate dimming.

This concept, again, wasn't entirely new. Patents for electrochromic devices dated back to the mid-1960s but no one had made a viable commercial product - and Gentex, sensing yet another opportunity to further expand its business, backed Byker's research into the electrochromic mirror.

In 1986, by which point Harlan Byker had joined Gentex, the company was ready to announce the first production electrochromic automotive rear-view mirror. Inside was a specially developed gel, sandwiched between pieces of glass, which when charged would darken - dimming the rear-view mirror. An optoelectronic sensor would measure the light intensity from behind and, as the brightness rose and fell, different currents would be applied to the mirror's gel to produce the optimum degree of dimming.


Gentex branded this set-up the 'Night Vision Safety' mirror and, in 1987, the first were dispatched to Ford for use in the 1988 model year Lincoln Town Car. General Motors then began offering it in 1989 and, not long after, the use of electrochromic mirrors spread to several other brands. Gentex quickly began boosting its margins, too, by integrating features such as compasses and light controls into the mirror itself. The technology proved successful and Gentex had soon established itself a substantial foothold in the competitive automotive marketplace.

Rival Donnelly hadn't completely missed the boat, however, and had been working on its own electrochromic systems. On seeing how popular Gentex's electrochromic offerings were, it quickly set about emulating the company's set-up - albeit using a very slightly different approach, presumably to circumvent certain key portions of Gentex's patent catalogue.

Subsequently, in the 1990s, several ugly legal battles ensued between the two companies. Cases came and went, and even a partnership was suggested then quashed, but ultimately the two ended up spending the sum total of $30 million to get nowhere - and both continued to manufacture their own electrochromic mirrors.

Interesting, Donnelly mirrors - perhaps due to differences resulting from the patent issues - always remained the most unreliable. As many Jaguar owners will tell you, the Donnelly electrochromic mirrors are prone to leaking when they are older. This marks the console below and also causes the mirror to fail; this is further credited as being one of the reasons why Gentex proved so successful, as its mirrors didn't suffer this issue.

By 1991, Gentex had introduced exterior electrochromic mirrors. By 1992, the NVS set-up was being used in more than 52 cars and the company recorded sales of $45 million. Gentex then set about expanding into other markets and, by 1996, had cornered 90 per cent of the electrochromic market. Customers included Ford, GM, Chrysler, BMW, Toyota, Nissan, Mercedes-Benz and more. In 2015, it shipped a total of 33 million auto-dimming mirrors.

Donnelly would eventually be bought out by Magna International in 2002, an automotive supplier which it had worked with for years, as Magna moved to bolster its own mirror operations. Donnelly, at the time, held 16 per cent of the market for auto-dimming mirrors. Gentex, on the other hand, then held 80 per cent. Many expected the combined force of Magna and Donnelly to make a substantial dent in Gentex's figures but, after the acquisition, Gentex's market share grew to 88 per cent and Magna's fell from 19 per cent to just 10 per cent.

Today, Gentex continues to supply a plethora of manufacturers and is further expanding the range of features available on its electrochromic mirrors - and, despite its lack of initial success in that area, it still makes a range of fire protection systems. And Bauer? He took up the position of chief executive of Gentex in 1986 and finally stepped down on 31 December 2017. When he left, many estimated the company to have a market value of some $6 billion - a far cry from the start-up that later netted just $17 million in market capitalisation following its IPO in 1981.

P.H. O'meter

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Comments (12) Join the discussion on the forum

  • skylarking808 20 Aug 2018

    My 1990's Beemer has an auto dim rear view mirror and I find it hard to judge distances at night.

    Prefer the old manual dip system.

  • unsprung 20 Aug 2018


    I'm appreciative of the auto-dimming rear-view mirror in my car; was a bit of a curiosity for me in the beginning

    years ago I pointed out this feature to an English friend as part of an introduction to my car; he gave it a thumbs-down

    but he also declined my offer to take the fob and give the car a drive, so who cares; horse to water and all that



  • iiievolution 21 Aug 2018

    Magna Donnelley is responsible for the “famous” E46 M3 leaking mirror that would leak the liquid it has down onto the center console and destroy it.

  • Lotusgav 21 Aug 2018

    Great article! Obviously took a while to research and it's not something I would have thought to look up - thanks for that👍

  • va1o 21 Aug 2018

    Lotusgav said:
    Great article! Obviously took a while to research and it's not something I would have thought to look up - thanks for that??
    Yep agree!

    I’ve always liked having auto dimming mirrors, think I’d miss if I had a car without! Interesting to know the story behind

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