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Non Accelerating Platen Detent

IP.com Disclosure Number: IPCOM000052931D
Original Publication Date: 1981-Aug-01
Included in the Prior Art Database: 2005-Feb-12
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

Vaughan, JL: AUTHOR

Abstract

Illustrated above is a platen detent mechanism consisting of a spur gear 10 directly attached to the platen 12 and pivoting about point 14. The roller detent 16 is pivoted on a stud 18 mounted on slider 20. The slider 20 is mounted on bellcrank 22 by studs 24. Bellcrank 22 is pivoted on pin 24. Spring 26 provides force F(s) on slider 20, while spring 28 provides moment M(b) on bellcrank 22. Slots 30 limit the motion of slider 20 to approximately 40% of the tooth-to-tooth spacing on gear 10.

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Non Accelerating Platen Detent

Illustrated above is a platen detent mechanism consisting of a spur gear 10 directly attached to the platen 12 and pivoting about point 14. The roller detent 16 is pivoted on a stud 18 mounted on slider 20. The slider 20 is mounted on bellcrank 22 by studs 24. Bellcrank 22 is pivoted on pin 24. Spring 26 provides force F(s) on slider 20, while spring 28 provides moment M(b) on bellcrank 22. Slots 30 limit the motion of slider 20 to approximately 40% of the tooth-to-tooth spacing on gear 10.

The function of the detent is to provide a fine location of the platen after it is rough-positioned by the drive mechanism (not shown). In order to accomplish this, the moment M(B) must be very large (compared to the driving torque). This results in a large energy transfer between the detent 16 and platen 12 during running, as the detent 16 is alternately driven out of the platen gear 10 by the drive mechanism and driven into the gear 10 by moment M(B). The net effect of this action is to cause the platen velocity to be sinusoidal (high accelerations), and results in skewing the typing paper relative to the platen. This makes it almost impossible to achieve character realignment on rollback.

The spring loading and slidability of the detent slider accomplishes the detenting function while minimizing the gear 10/detent 16 energy transfers, thereby decreasing the Platen 12 accelerations and improving the paper skew/slip condition.

As the platen 12 i...