====== Open heart ======
{{wst>image_cr|Frederique Constant|Heart Beat Manufacture Moonphase Date}}

An **open heart** [[dial]] is has a hole through which the [[escapement]] can be viewed.

===== History =====
[[Revue]] used the name "Open Heart" on a line of mechanical watches as early as [[1979]]. These featured hand-finished mechanical movements visible through an aperture above the balance. The [[1982]] line features a circular aperture at the center of the dial.

In [[1994]], [[Frederique Constant]] used the name for their "[[Frederique Constant Heart Beat|Heart Beat]]" model. Since then, the open heart concept and terminology has spread throughout the industry. It is a limited form of [[skeletonization]] that focuses on the [[escape wheel]] and [[anchor]] (the most active parts of the movement) rather than other [[wheels]].

Not all movements are amenable to open heart dials. The [[escapement]] must be visible through the [[top plate]], either by design or through skeletonization of the plate. The escapement must also be oriented harmoniously to the overall dial layout, typically between 6 00 and 10 00 on the dial. Furthermore, complications like a [[date wheel]] can interfere with visibility so most open heart watches lack these.

===== See Also =====
  * [[Skeleton]]
  * [[Openworked]]
  * [[Dial]]


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