The following invention relates to an improved lens apparatus for use in a head up display, particularly for providing a HUD with an active virtual one which has variable and selectable distance to the user. The compactor further includes an electronic control mechanism configured to activate the dispensing mechanism, and further configured to deactivate the dispensing mechanism responsive to data indicating an extent of coverage of the outer surface with the liquid is sufficient. The brake drum has a brake face on an inner peripheral surface thereof, and the brake shoe has a contact surface that contacts the brake face of the brake drum to apply a braking force to the brake drum.