RK Watch Service

Seiko HAQ wristwatch with a cesium atomic oscillator (chip-scale atomic clock)

As I discussed in below quote, Seiko has patented a new HAQ method with dual oscillators (likely based on an older Citizen method for which the patent has expired).

CitizenPromaster said:
———— NEW SEIKO PATENT WARNING ————–

What is also jumping out at me this time, is that JPS57116287A recently got cited by none other than Seiko Epson.

View attachment 18861739

The Japanse characters don’t give anything away to us…

Seiko HAQ wristwatch with a cesium atomic oscillator (chip-scale atomic clock)

What HAQ watch are you sporting today?

My 1st and only at the moment. I am loving this thing.

High Accuracy Quartz watches News from the Watch Industry rk watch service

Citizen frequency correction patents

This thread is a discussion of three Citizen patents highlighted by @CitizenPromaster in the pinned TC thread.

This thread is not so much about this technology’s place in Citizen’s product line, if any, but about the invention on its own merits as an aid to energy-efficient quartz watch accuracy.

Attached as PDF, the US version of these patents are…

Citizen frequency correction patents

High Accuracy Quartz watches

Citizen cal. 1730

This thread is to collect and organize all information on the Citizen ‘4 Mega’ cal. 1730 launched in 1981, as existing information is scattered such as in the TC thread.

The Exceed 4 Mega watches powered by this caliber were the last known Citizen AT-cut wristwatches before the cal. 0100 pocket watch shown at BaselWorld 2018 and First Series wristwatches released to the market in 2019.