Digital audio signal playback apparatus with scratch effect control device

A digital audio signal playback apparatus, comprising:

• a housing having a top wall formed with an opening;
• a data reading device mounted in said housing and operably associated with a data recording medium for reading digital audio data recorded in the data recording medium;
• a pivot axle unit defining an axis, and including a rotatable inner spindle and an outer sleeve sleeved rotatably on said inner spindle,
• said outer sleeve having a platter connecting portion extending through said opening in said top wall of said housing so as to be disposed outwardly of said housing, and an encoder connecting portion disposed inside said housing,
• said inner spindle having a platter connecting section extending upwardly through said platter connecting portion of said outer sleeve, and an encoder connecting section extending downwardly through said encoder connecting portion of said outer sleeve;
• a turntable unit disposed above said top wall of said housing, and including a lower platter member coupled co-axially to said platter connecting portion of said outer sleeve for co-rotation therewith, an upper platter member superposed on said lower platter member and coupled co-axially to said platter connecting section of said inner spindle for co-rotation therewith, and a coupling interlayer interposed between and in friction contact with said lower and upper platter members, said upper platter member being rotatable together with said lower platter member as a result of friction between said coupling interlayer and said upper and lower platter members;
• a driving unit mounted in said housing and coupled to said lower platter member for driving rotation of said lower platter member about said axis;
• a first encoder disc mounted co-rotatably on said encoder connecting portion of said outer sleeve and formed with a first pick-up pattern;
• a second encoder disc mounted co-rotatably on said encoder connecting section of said inner spindle and formed with a second pick-up pattern;
• a first pick-up device proximate to said first encoder disc and interacting with said first pick-up pattern for generating a first control signal representative of angular velocity and rotational direction of said first encoder disc;
• a second pick-up device proximate to said second encoder disc and interacting with said second pick-up pattern for generating a second control signal representative of angular velocity and rotational direction of said second encoder disc;
• and
• a control unit connected electrically to said first and second pick-up devices and said data reading device, said control unit controlling output of the digital audio data read by said data reading device in accordance with the first and second control signals from said first and second pick-up devices so as to impart a scratch effect to the digital audio data.