Hewlett-packard Development Company, L.p.

Matthew Jason Janssen

James R Cole

Dennis Raymond Esterberg

James W Ring

Jeffrey Allen Nielsen

Norman L Berger

Andrew L Van Brocklin

Bruce Cowger

Timothy Wagner

A technique includes coupling outlets of a first ink supply and a second ink supply together to provide ink to a printhead of a printer; and pressurizing the first ink supply and the second ink supply with air so that an air pressure of the first ink supply has a different air pressure than an air pressure of the second ink supply. The technique includes monitoring an ink-to-air differential pressure of the first ink supply or the second ink supply; and detecting an ink state for the printer based on the monitored ink-to-air differential pressure.

Detecting ink states for printers based on monitored differential pressures

In some examples, an apparatus includes a pressure sensor, and a controller to determine, based on pressure data from the pressure sensor, an amount of time to depressurize a fluid supply from a first pressure to a second pressure, and determine a level of a fluid in the fluid supply based on the amount of time to depressurize the fluid supply from the first pressure to the second pressure.

Fluid supply levels based on fluid supply depressurizations

In one example, a method for determining an out-of-liquid condition of a liquid supply for an inkjet printer. The method includes acquiring, during printing, a sequence of data points, each data point comprising a differential liquid/air pressure at the liquid supply measured with a sensor and a corresponding cumulative amount of liquid delivered from the liquid supply. The method further includes generating a curve using the data points. The method also includes determining, from a predetermined characteristic of the curve, whether the out-of-liquid condition exists. The characteristic is independent of at least one of a gain and an offset of the sensor.

Determining an out-of-liquid condition

An example printhead assembly includes a housing, nozzles and a collapsible container within the housing to supply ink to the nozzles. The collapsible container includes a top wall, a bottom wall, first and second side walls that form an interior and a spring assembly within the interior. The first flexible wall includes a first amount of excess material. The second flexible wall includes a second amount of excess material less than the first amount of excess material such that motion of the first flexible wall of the collapsible container is constrained against movement to a lesser extent as compared to the second flexible wall. The first flexible wall faces the sensor. A sensor assembly is coupled to the housing and includes a sensor to provide a sensor signal indicating the amount of ink within the collapsible container.

Collapsible container and sensor

One example of a system includes a bulk ink assembly, a printhead assembly, a valve, and a controller. The bulk ink assembly receives a bulk ink supply. The printhead assembly includes nozzles to eject ink drops, a collapsible container to supply ink to the nozzles, and a sensor to provide a sensor signal indicating the amount of ink within the collapsible container. The valve supplies ink to the collapsible container from the bulk ink assembly in response to a control signal. The controller provides the control signal based on the sensor signal to regulate the amount of ink in the collapsible container and to provide an out of ink signal based on the sensor signal indicating the bulk ink supply is effectively empty.

Printhead assembly

One example of a printhead assembly includes a housing including sidewalls, nozzles to eject ink drops, a collapsible container, and a sensor assembly. The collapsible container is within the housing to supply ink to the nozzles. The collapsible container includes flexible sidewalls and a spring assembly between the flexible sidewalls. The sensor assembly is coupled to the housing and includes a sensor to provide a sensor signal indicating the amount of ink within the collapsible container.

An optical disc is rotated using a spindle motor of an optical disc device, at no more than 600 revolutions per minute (RPM). The spindle motor has at least three coil groups, where each coil group has one or more coils. While the optical disc is rotating, at least one of the coil groups generates a back electromagnetic force (EMF) signal. The back EMF signal is used to determine marking positions on the optical disc. An optical beam is used to mark the optical disc at the determined marking positions.

Controlling optical disc

Whether an optically writable label surface of an optical disc is suitable for having an image formed thereon is determined. A detectable number of encoder spokes on a control feature area of the optical disc is counted as the optical disc is rotated. Where the detectable number of encoder spokes is other than a predetermined value, an error condition with respect to the optically writable label surface of the optical disc is indicated.

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Corvallis, OR, United States of America

Matthew Jason Janssen