Cassette tape player having circuit for detecting reverse rotation of take-up reel
AssigneeFord Motor Company
InventorsGerald W. Tarpley, Jr., Kenneth C. Miller, Karen M. Carlson
Life of this patent
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Abstract
A system for preventing improper tape feed in a cassette tape player uses pulse width measurements from the take-up reel output signal to sense normal or aberrant tape feeding conditions. The pulse width of the output signal is compared with a predetermined range of pulse widths associated with normal tape operation. The range is variable as a function of the rotational frequency of the take-up reel and is updated periodically to reflect changes in the diameter of the take-up reel as the tape plays. If the pulse width of the output signal falls outside of the predetermined range, it denotes an aberrant tape feeding condition.
Claims9
A tape player apparatus for playing a cassette tape cartridge having a magnetic tape which is wound between a take-up reel and a supply reel, the apparatus comprising:
- a drive motor;
- a take-up reel spindle driven by the drive motor, the take-up reel spindle having a rotational frequency;
- a supply reel spindle;
- means for sensing the rotational frequency of the take-up reel spindle, the sensing means producing an output signal having a pulse width inversely proportional to the rotational frequency;
- means for measuring the pulse width of the output signal;
- means for comparing the pulse width of the output signal with a variable predetermined range of pulse widths, the range being variable as a function of the rotational frequency of the take-up reel, said comparing means further comprising a microprocessor based control using a comparison function defined by:
- t.sub.low -Y.ltoreq.t.sub.current .ltoreq.t.sub.high +X for a normal operating condition;
- and
- (t.sub.current <t.sub.low -Y) or (t.sub.current >t.sub.high +X) for an aberrant operating condition where t.sub.low and t.sub.high are first and second pulse width values determined by rotating the take-up reel spindle a predetermined rotation wherein the sensing means produces the output signal having a plurality of pulses, each pulse having a pulse width which is inversely proportional to the rotational frequency and then ranking the pulse width values of the plurality of pulses where:
- t.sub.low is the lowest pulse width value,
- t.sub.high is the highest pulse width value,
- t.sub.current is the pulse width being measured,
- X is a first constant related to the values of t.sub.low and t.sub.high, and
- Y is a second constant related to the values of t.sub.low and t.sub.high, wherein each of the above variables are updated in a loop function until a control status signal is initiated;
- means for interrupting operation of the take-up reel spindle in response to the pulse width falling outside of the predetermined range thereby denoting an aberrant tape condition.
A tape player apparatus for playing a cassette tape cartridge having a magnetic tape which is wound between a take-up reel and a supply reel, the apparatus comprising:
- a drive motor;
- a take-up reel spindle driven by the drive motor, the take-up reel spindle having a rotational frequency;
- a supply reel spindle;
- means for sensing the rotational frequency of the take-up reel spindle, the sensing means producing an output signal having a pulse width inversely proportional to the rotational frequency;
- means for measuring the pulse width of the output signal;
- means for comparing the pulse width of the output signal with a variable predetermined range of pulse widths, the range being variable as a function of the rotational frequency of the take-up reel;
- means for interrupting operation of the take-up reel spindle in response to the pulse width falling outside of the predetermined range thereby denoting an aberrant tape condition, wherein the range of pulse widths is defined by:
- t.sub.low -Y.ltoreq.t.sub.current .ltoreq.t.sub.high +X for a normal operating condition, and
- (t.sub.current <t.sub.low -Y) or (t.sub.current >t.sub.high +X) for an aberrant operating condition where:
- t.sub.low is the lowest pulse width value occurring during a predetermined time period,
- t.sub.high is the highest pulse width value occurring during the predetermined time period,
- t.sub.current is the pulse width being measured,
- X is a first constant related to the values of t.sub.low and t.sub.high, and
- Y is a second constant related to the values of t.sub.low and t.sub.high, wherein each of the above variables are updated in a loop function until a control status signal is initiated.
Dependencies are inferred from the claim text.