A print media sensor (10) according to the present invention determines a
print medium type by utilizing an ultrasonic transducer (22) to vibrate a
print medium (28) at a resonant frequency of the print medium (28). The
print medium (28) is irradiated with light from an LED (20). Sensors (24,
26) measure the amount of light reflected from and transmitted through the
print medium (28) while it is being vibrated at the resonant frequency.
The ratio of the reflected to transmitted light is compared to a stored
table of ratios that are associated with the resonant frequencies of
specific print medium types and print medium ink volume and application
rates. The results of these comparisons are used to determine the print
medium type and the associated ink volume and application rate to be used
for printing on the print medium (28).
