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+====== Seiko ultra-thin quartz ======
+{{wst>author|[[Foskett, Stephen|Stephen Foskett]] ([[https://grail-watch.com/|Grail Watch]])}}
+[[Seiko]] produced a range of [[ultra-thin quartz]] movements in the 1970s and 1980s, culminating in the 0.85 mm [[Seiko 9A|Cal. 9A85]] in [[1989]], which remains the [[ultra-thin|thinnest]] [[quartz]] analog movement ever produced [[as of 2020]].
+===== History =====
+Seiko produced the first quartz watch for sale to the public in [[1969]], the groundbreaking [[Seiko Astron]]. Its [[Seiko 35|Cal. 35SQ]] evolved rapidly over the few years it was produced, but the successor movement, [[Seiko 38|Cal. 38]], set the template for future quartz movements, with a [[stepper motor]] and [[integrated circuit]] divider on its introduction in [[1972]]. By the mid-1970s, [[Seikosha|the two Seiko factories]] were rapidly iterating, releasing a new movement nearly every year throughout the decade.
+Seiko produced the first movement compact enough for a ladies watch, [[Seiko 03|Cal. 03]], in [[1972]], and replaced this in [[1974]] with the more robust [[Seiko 41|Cal. 41]]. Although not a thin movement at nearly 4 mm thick, it nevertheless showed that quartz technology could be miniaturized. Mass-produced miniature 32 KHz tuning fork quartz crystals, [[CMOS]] [[IC]]s, compact [[stepper motor]]s, and advanced batteries were all rapidly advancing and coming to production.
+[[Citizen]] and Seiko initiated a so-called "[[ultra-thin quartz|thin watch war]]" in [[1978]], with Citizen first to market with the [[Citizen Exceed Gold|Quartz 790, also called the Exceed Gold]]. The watch was moderately thin at 4.1 mm, but the movement, [[Citizen 790|Cal. 790]] was remarkable. It measured just 0.98 mm thick, though the battery and [[hand set]] more than doubled this. The watch was nevertheless impressive, and Seiko (and the Swiss [[Delirium]] project) set about beating their record.
+Seiko was next to market, announcing the ultra-thin [[Seiko 93|Cal. 9320]] on July 20, [[1978]]. It measured 0.90 mm thick, setting a new record just a few months after Citizen, and was featured in an ultra-thin watch that measured just 2.5 mm. These caused an international stir, with a high-profile release at famed New York jeweler Tiffany & Co. at a price of $5,000. For the first time, a Japanese watch was the high-dollar focus of American tastes. Sold under the new [[Credor]] label in Japan, the [[Seiko HGY|HGY614 (9320-7000)]] feature Seiko branding on the dial and can be seen as a stepping stone between the [[Grand Seiko]] lines of the 1960s and [[Credor]] and [[Grand Seiko]] of the 1990s and beyond.
+These releases from Japan caused great concern for the [[North American Watch|North American Watch Company (NAWC)]], which had been the leader in high-end ultra-thin watches in America with the [[Piaget]] brand. They demanded that [[Ebauches SA]] produce a thinner watch, leading to the creation of the [[Delirium]], which was sold in the United States under the [[Concord]] brand. They announced their 1.98 mm watch on January 12, [[1979]], which featured a remarkable 1.1 mm battery from [[Renata]].
+Later that year, ETA and Concord announced the Delirium II which, at just 1.43 mm, was impractical for everyday wear but nevertheless set a record. The Delirium movement was integrated with the case, however, making comparison of movement size difficult. Seiko responded to the Delirium with an even thinner watch to house Cal. 9320. The Seiko/Credor 9320-400x was just 1.79 mm thick, but it arrived a few months after the thinner Delirium II. Both were impractical watches designed for collectors and museums, and both are quite rare to this day. The ultimate expression of this impractical line was the Delirium IV, which appeared in December [[1980]]. The entire watch was 0.98 mm thick, with a special battery and engraved crystal discs rather than hands.
+Both Citizen and Seiko also created more practical versions of their ultra-thin watch movements, and these sold for far less than the ultra-thin leaders. [[Daini Seikosha]] bested rival [[Suwa Seikosha|Suwa's]] movement by 0.01 mm with their [[1980]] [[Seiko 67|Cal. 6720]], which was also smaller in diameter. At 18x13x0.89 mm, it would become one of the smallest movements ever made. Their [[Seiko 2F|Cal. 2F family]] of [[1983]] was also impressively small, measuring 15.55 mm diameter and 1.39 mm thick. Suwa released another family of ultra-compact movements in [[1984]]. Their [[Seiko 5A|Cal. 5A family]] measured 1.3 mm thick and was used in watches from Seiko's recently-acquired [[Lassale]] brand as well as Credor and Seiko.
+The final ultra-thin watch movement from Seiko, and still the world's thinnest movement, appeared in [[1989]], fittingly in a watch that celebrated the 20th anniversary of the [[Seiko Astron]]. The [[Seiko SCQX|SCQX 20th Anniversary]] watch was a wearable 3.36 mm thin and houses the remarkable 0.85 mm [[Seiko 9A|Cal. 9A85A]]. The movement was created by Suwa Seikosha (now called Seiko Epson) and was finished and decorated in high-end style despite being housed in a closed-back watch. The gold Anniversary watch sold for over 1 million Yen, more than twice as much as contemporary gold Seiko watches, and remains a collectible.
+===== See Also =====
+  * Seiko ultra-thin movements
+    * [[Seiko 93|Cal. 9320]] (1978) - 0.90 mm
+    * [[Seiko 67|Cal. 6720/6730]] (1980) - 0.89-1.10 mm
+    * [[Seiko 2F|Cal. 2F50]] (1983) - 1.39 mm
+    * [[Seiko 5A|Cal. 5A50/5A54/5A70/5A74]] (1984) - 1.30 mm
+    * [[Seiko 9A|Cal. 9A85]] (1989) - 0.85 mm
+  * [[Ultra-thin]]
+  * [[Ultra-thin quartz]]
+  * [[Delirium]]
+  * [[Citizen Exceed Gold]]
+===== External Links =====
+  * [[https://www.plus9time.com/blog/2020/12/12/worlds-thinnest-movement-seiko-9a85|World's Thinnest Movement - Seiko 9A85]]
+{{tag>Seiko Ultra-thin_watches}}