The present invention pertains to a professional-type chair such as used by dentists, ophthalmologists, and other types of medical or quasi-medical professions in which adjustable operatory chairs are useful. Also, details and features of mechanisms found in such types of chairs are frequently employed in chairs used in barbering and beauty culture. One of the most common features now found in this type of chair comprises an upholstered seat to the rear edge of which a back rest is pivotally connected, and power means are employed to operate the back rest between substantially upright and rearwardly extending horizontal positions. Appropriate control means are employed to effect operation of one or more electric motors which effect movements of the back rest relative to the seat. In addition, many types of chairs of this type include a leg rest and/or a foot rest, the leg rest being pivotally connected to the seat adjacent the forward edge thereof and movement of the leg rest frequently occurs simultaneously with pivotal movement of the back rest relative to the seat.
Effecting control of the back rest and/or leg rest relative to the seat is accomplished in certain modern types of chairs of the type referred to above by means of rather sophisticated electrical circuitry, batteries of push buttons by which various switches are operated to start and stop the movements of the back and/or leg rests relative to the seat, as well as raising and lowering the seat with respect to a supporting base. Examples of such control in chairs of this type are found in various patents, including U.S. Pat. No. 3,357,740 to Vaughn et al, dated Dec. 12, 1967, and U.S. Pat. No. 3,578,379 to Taylor, dated May 11, 1971. Notwithstanding such sophisticated control systems, especially for moving the back and leg rests relative to a seat, as disclosed in said patents, it now has been found that in adjustable operatory chairs of the type referred to above, it is desirable to provide adjustable, programmable control means by which, for example, any adjustable setting may be effected quickly and manually by the operator of the chair to dispose the back rest and/or leg rest at a desired position intermediately between the limits of movement thereof, such as between substantially vertical position and horizontally extending position, with respect to both the back rest and/or leg rest.