Editing Cherry MY (section)

==Description==
Cherry MY switches use discrete actuator modules over a three-layer [[membrane]] assembly; the membrane sheets are allegedly made of vinyl.{{citation needed}} The switch technology is referred to by Cherry as "'''FTSC'''". A [[:File:Cherry G81-1800 datasheet.pdf|Cherry G81-1800 datasheet.pdf]] is one of the rare examples of "FTSC" being expanded to "Full-Travel Sealed Contact". 

The earliest patent was filed in 1984, while the switch is claimed to have been introduced in 1987.{{citation needed}} Since its introduction, three separate actuator designs have been encountered. Although all three appear to be very different, the basic construction is identical. The springs in all three appear to be identical; the changes appear to be solely to the design of the shell and [[slider]].

Each actuator module contains two springs: a small helical return spring and a horizontal leaf spring that applies pressure to the membrane. The leaf spring serves as a [[motion reducer]] and functions similarly to [[prong over membrane]] switches by deflecting by a small amount in proportion to the force applied to the helical spring. The leaf spring is however operated directly by the slider; a bar that runs across the inside of the switch provides the post that locates the helical spring, and the helical spring does not come into contact with either the membranes or the leaf spring.

The base of the shell has been measured as approximately 18.7 mm square for Type 1, and approximately 18.8 mm square for Type 3. The shell height measures around 11.0 mm for Type 1, and around 10.8 mm for Type 3.

The leaf spring has two folds; one fold is approximately 90° and allows the spring to be pressed up into the shell. The other fold is very shallow and appears to be there to concentrate pressure onto the membrane assembly when the slider presses down on it.

The actuator modules are supported by the metal backplate behind the membrane assembly. Each module has two feet, each with three "toes". The feet push through holes in the membrane assembly, and small pegs are forced between the "toes" to push them apart and stop the actuator from being pulled out of the keyboard. The actuator modules thus rest directly on the top membrane sheet; as such, the leaf spring is only expected to move downwards a short direction, as the maximum travel of a membrane assembly is under 1/10th of a millimetre.

The slider can only be inserted in one orientation. Of the four grooves in the shell that guide the slider, one is wider, and the corresponding portion of the slider is wider to match.

Cherry's "The keyboard pros!" Catalog 06/07 provides the switch lifetime of 50 million keystrokes, and presents a force curve giving 20 cN preload, 60 cN actuation at just over 2 mm, and around 110 cN peak force; the extra 15 cN comes from the fact that the force curve is progressive rate, curving upwards just after actuation.