Inside the development of TXI: an interview with Hiroyuki Tomooka

Hiroyuki Tomooka is one of OPTEX's leading experts in intrusion detection sensor development, with more than three decades experience. He is listed on more than 70 patents and registered designs worldwide and is one of the engineers behind the new TXI series. We spoke to him about his career, the thinking behind Triple AND Logic, a world-first technology at the heart of the TXI, and the engineering challenge of developing a compact, high-mounted curtain sensor.

An engineer from the start

I understand you were interested in making things from an early age…
"When I was in elementary school, I made plastic models and fishing lures almost every week," Tomooka recalls. Technology classes in junior high led him towards a technical high school, then a science and engineering degree. "Above all, I enjoyed making things through mechanical design, so I imagined I would probably become an engineer."

He joined OPTEX in 1991 and began developing security sensors, starting with the FX-360, a ceiling-mounted sensor that remains on the market today. “After that, I temporarily worked in departments related to water quality measurement, radiation thermometers, and business development for building automation. Those experiences later proved very valuable. Fundamentally, however, I have always worked in security products and specifically passive infrared sensors.”

Working towards the right solution

What exactly is a curtain narrow sensor?
"It's a type of intrusion detector with a major market in Europe, particularly Italy, with a history of more than 20 years," Tomooka explains. "'Narrow refers to the slim width of the detection area, while 'curtain' means there are no gaps." Curtain sensors create a detection zone running parallel to a building's exterior wall and are part of a wider outdoor passive infrared detection category.

Tomooka had already helped establish the market for outdoor PIR sensors with another of his inventions: the VX-40, a low-mounted sensor. Its innovation was pet-tolerant performance, achieved through a two-zone design, upper and lower, that triggered an alarm when both zones were crossed together, helping to reduce false alarms caused by small animals. Sales, in Tomooka’s words, became "a tremendous hit." The patented technology won an industry award and proved so influential that competitors adopted it the moment the patent expired in 2016.

Its success created demand for something OPTEX didn't yet offer: a high-mounted equivalent. However, it took almost twenty years for OPTEX to launch a sensor in this category.

"There certainly was a market," Tomooka says. Sensors were already available, but they could either falsely detect small animals or fail to respond even when a person was intruding. “Every proposal fell short in one respect: it did not meet OPTEX’s quality standards." Customers wanted reliable detection, but also easy installation, a strong design and a compact size.

Triple AND Logic technology was developed to address these requirements together. While the underlying principle may sound simple, the engineering challenge was not. Adding more components would make the product larger and more complex.

"I had to devise a technology that creates three zones while keeping the apparent part count unchanged."

A unique sensor-element arrangement creates three detection zones

When and how did the idea for Triple AND Logic emerge?
"I don't clearly remember when, but the thought was something like: if we combine a DUAL-type element with a QUAD-type element, couldn't we achieve Triple AND with only two elements? I remember thinking, 'This is it! This will work perfectly for a curtain sensor.' At that moment I could already see the finished product."

Tomooka describes his creation process as letting ideas rest: "When I'm thinking about many things, I scribble down whatever comes to mind: a design, a structure, a detection-zone pattern. By letting ideas sit in a mental drawer, when the right moment comes, something in that stock connects to a product."

With TXI, once the core idea appeared, the concept itself was not the biggest challenge. The engineers working on the product faced the more difficult task of making it work.

One of those engineers, Kataoka-san, handled electrical design, had to fit everything onto a circuit board two-thirds the size of previous products, while increasing the number of sensor elements to two and circuits to three. "He went through considerable difficulty," Tomooka explains. "Even after reducing the design as far as possible, requests for additional functions kept arriving.”

Looking back at the earliest TXI sketches, Tomooka-san describes Kataoka as “the person who makes the impossible fit.” Technically, the core challenge was balancing detection performance, zone layout, false-alarm resistance, compact size, and ease of installation.

Do you have a philosophy about quality and performance?

"Not exactly a philosophy, but experience has given me a firm internal line: performance must never fall below this point."

He distinguishes between accepting a sound product while knowing it could still be refined and giving up on a worrying area and simply hoping it works. "With the latter, you usually pay for it later.

“OPTEX products have long life cycles; the sensor I worked on when I joined is still being sold. My ideal is a product that promotes itself. With TXI, I believe we created a living product that communicates the intentions of those who made it."