Appeal No. 2002-1788 Page 8
Application No. 09/217,667
Xs3 is the actual lateral position of the paper at sensor 134 when the paper
is at datum 3.
Xdisp is the requested lateral displacement of the paper as it moves from
datum 2 to datum 3. If the sensors were perfect Xdisp=-Xs2 would cause the paper
to move to Xs3= 0.
c(Xs2) is the correction to be added to the measured sensor values. As the
notation suggests, it is a function of the position on the sensor. This invention
provides a method to determine this correction.
e2(Xs2) and e3(Xs3) are the sensor errors; the difference between the actual
and measured paper position. These errors are a function of the position on the
sensor.
From these definitions it follows that:
Xs3=X3+e3(Xs3) (1)
X3 =X2+Xdisp (2)
Xdisp=-(Xs2+c(Xs2)) (3)
X2=Xs2-e2(Xs2) (4)
Combining these relations, one obtains an expression that relates the
sensor measurements to the sensor correction.
Xs3+c(Xs2)=e3(Xs3)-e2(Xs2) (5)
What follows is a description of the method used to determine the
correction c(Xs2) for a particular value of Xs2, call it X*s2. For complete sensor
calibration this method is applied at several points along the sensor. To facilitate
the explanation of the method consider the following thought experiment.
Feed paper to the lateral position X*s2. Randomly choose a value for the
correction c and, using relation (3), determine Xdisp. Perform the registration
move, measure the resulting Xs3 and calculate the value of the quantity Xs3+c.
Repeat this procedure using various different values for the correction c. By
doing this we have experimentally generated Xs3+c as a function of c. Call this
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