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+====== Seiko 41 ======
+Seiko's **Cal. 41** was the first production [[quartz]] movement small enough for ladies watches. It was produced by [[Suwa Seikosha]] starting in [[1974]] and was produced in volume in many different versions for most of the decade.
+===== History =====
+[[Seiko]] was raced to develop a [[quartz watch]] movement in the 1960s, and delivered their first [[Seiko 35|Cal. 35]] movement to the [[Neuchatel Observatory]] in late [[1967]], just a few months after the [[CEH]] delivered their [[Beta 21|"Beta" quartz movement prototypes]]. A product of [[Suwa Seikosha]], Seiko offered Cal. 35 SQ for sale in the [[Seiko Astron]] watch on Christmas Day, [[1969]]. Suwa rival [[Daini Seikosha]] developed [[Seiko 36|Cal. 36]] and launched it in [[1970]], but neither movement was truly produced in volume. Suwa's second quartz movement was [[Seiko 03|Cal. 03]], was the world's first quartz movement small enough for ladies watches but was also not produced in volume.
+In [[1974]], Suwa Seikosha released Cal. 41, a volume production quartz ladies watch movement. This was a modern movement designed similarly to the contemporary [[Seiko 38|Cal. 38]], also from Suwa. Cal. 41 was smaller overall, with a semi-tonneau shape that fit in narrow watches. It measured 19.4 mm diameter at the widest, and was 3.8 mm thick for the smallest examples, which lack a seconds hand. This gave Seiko bragging rights for producing "The World's Thinnest Quartz Watch" in [[1974]] advertisements.
+Like modern quartz movements, it used a 32 KHz [[quartz]] crystal and [[stepper motor]] actuating every second when equipped with a seconds hand or every five seconds otherwise. They are fitted with a trimmer condenser to adjust the rate, and are specified at less than 15 seconds variance per month. They also include a special [[thermocompensation|temperature-sensitive condenser]] to adjust to temperature variations. Battery life is better than 1 year.
+The movement is designed to be easily serviceable with replaceable components The coil block and circuit block can be swapped out, and are often replaced during servicing with upgraded types.
+===== Variants =====
+  * 4100A - Time-only, 4.0 mm thick, 3 jewels
+  * 4110A - Time-only, no seconds hand, 3.8 mm thick, 2 jewels
+  * 4120 - Time-only, mainstream watches
+  * 4122 - Date, mainstream watches
+  * 4130A/4130B - No seconds hand, high-end watches
+<WRAP ud ud_mov>
+**Description:**
+  * [[Quartz]] movement
+**Functions:**
+  * Hours, minutes, central seconds
+  * Optional [[date]]
+**Data:**
+  * 2 or 3 [[jewels]]
+  * 32 KHz
+  * 19.4 mm diameter
+  * 3.8 or 4.0 mm thick
+**Production period:**
+  * [[1974]]-[[1977]]
+  * Predecessor [[Seiko 03]]
+</WRAP>
+{{tag>Movements Quartz_movements Seiko_calibres Seiko_quartz_calibres}}