Radiant energy – Photocells; circuits and apparatus – Optical or pre-photocell system
Reexamination Certificate
2005-02-22
2005-02-22
Luu, Thanh X. (Department: 2878)
Radiant energy
Photocells; circuits and apparatus
Optical or pre-photocell system
C250S576000, C347S019000, C347S074000, C347S081000
Reexamination Certificate
active
06858860
ABSTRACT:
In an apparatus for measuring a natural period of liquid in a pressure chamber formed in a head device which is provided with a nozzle orifice communicated with the pressure chamber and an actuator which varies pressure of the liquid contained in the pressure chamber, a driver generates a plurality of drive signals, each of which drives the actuator to eject a liquid droplet from the nozzle orifice under a condition different from the conditions established by the other drive signals. A light emitter emits a light beam so as to intersect a space through which the liquid droplet passes. A light receiver receives the light beam which has been passed through the space. A first calculator calculates an ejection velocity of the liquid droplet based on a timing at which the actuator is driven and a change in a photo-receiving state of the light receiver, with regard to every drive signal. A second calculator calculates a natural period of the liquid based on a change in the ejection velocity which is obtained from the plural drive signals.
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Endo Hironori
Hosono Satoru
Teramae Hirofumi
Luu Thanh X.
Seiko Epson Corporation
Yam Stephen
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