Appeal No. 1998-2513
Application No. 08/171,427
the independent claims (1, 5, and 12) do not contain the language “the measured speed.”
Appellant’s Figure 3, as described at page 3, line 11 through page 4, line 18 of the
instant specification, discloses a capstan servo system which compares the actual speed
of capstan motor 27 with a reference value. The error calculated by speed error detector
21 is changed into a degree of speed control by speed controller 22. The speed control
signal is output to adder 25, and ultimately to motor driver 26. There is thus a feedback
loop which utilizes the measured speed of motor 27.
Another feedback loop operates on capstan tracking error by means of phase
comparison between a control pulse reproduced by fixed head 28 and the head switching
pulse. The degree of tracking error is further processed by capstan phase controller 24,
with the degree of capstan tracking control being output to adder 25. The input to motor
driver 26 is thus the summation of the signals from the speed control and the tracking
control.
Takeda discloses in Figure 1, and describes principally at page 13, line 3 through
the last line of page 15 of the English translation, a servo circuit which includes a “tracking
error generating part” 200a. A tracking error signal is output by “sample hold” circuit 19,
which is relayed to “addition amplifier” 1 through amplifier 20 and low-pass filter 21.
Control circuit 24 uses input from the tracking error signal at “sample hold” circuit 19, and
outputs a signal to “reference voltage generation circuit” 7b, which in turn outputs a signal
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