Inkjet printer and method for use thereof

An ink jet printer, comprising:

• a reference plane near and parallel to a media surface plane;
• a first sensor configured to detect a presence of a first ink drop at a first predetermined distance from the reference plane;
• a second sensor configured to detect a presence of a second ink drop at a second predetermined distance from the reference plane;
• and
• a processing device configured to calculate a velocity of the first ink drop and the second ink drop based on:
• the first predetermined distance;
• the second predetermined distance;
• a first time period between a printhead firing the first ink drop and said first sensor sensing the first ink drop;
• and
• second time period between said printhead firing the second ink drop and said second sensor sensing the second ink drop,
• wherein at least one of said first sensor and said second sensor has an outside surface, said at least one of said first sensor and said second sensor being configured to detect a presence of at least one of the first ink drop and the second ink drop on said outside surface.

An ink jet printer, comprising:

• a reference plane near and parallel to a media surface plane;
• a first sensor configured to detect a presence of a first ink drop at a first predetermined distance from the reference plane;
• a second sensor configured to detect a presence of a second ink drop at a second predetermined distance from the reference plane;
• and
• a processing device configured to calculate a velocity of the first ink drop and the second ink drop based on:
• the first predetermined distance;
• the second predetermined distance;
• a first time period between a printhead firing the first ink drop and said first sensor sensing the first ink drop;
• and
• a second time period between said printhead firing the second ink drop and said second sensor sensing the second ink drop,
• wherein said first sensor includes two first terminals defining a first gap therebetween, said first sensor being configured to detect a presence of ink in said first gap as a reduction in a first electrical resistance between said first terminals, said second sensor including two second terminals defining a second gap therebetween, said second sensor being configured to detect a presence of ink in said second gap as a reduction in a second electrical resistance between said second terminals.

A method of calculating at least a component of ink drop velocity in an ink jet printer, said method comprising the steps of:

• jetting at least one first ink drop from a printhead firing plane;
• detecting when the first ink drop is a first predetermined distance away from a reference plane;
• measuring a first time period between said jetting and said detecting of the first ink drop;
• jetting at least one second ink drop from the printhead firing plane;
• detecting when the second ink drop is a second predetermined distance away from the reference plane;
• measuring a second time period between said jetting and said detecting of the second ink drop;
• and
• dividing a difference between the first predetermined distance and the second predetermined distance by a difference between the first time period and the second time period.

A method of calculating at least a component of ink drop velocity in an ink jet printer, said method comprising the steps of:

• jetting at least one first ink drop from a printhead firing plane;
• detecting when the first ink drop is a first predetermined distance away from a reference plane;
• measuring a first time period between said jetting and said detecting of the first ink drop;
• jetting at least one second ink drop from the printhead firing plane;
• detecting when the second ink drop is a second predetermined distance away from the reference plane;
• measuring a second time period between said jetting and said detecting of the second ink drop;
• dividing a difference between the first predetermined distance and the second predetermined distance by a difference between the first time period and the second time period;
• providing a first ink drop sensor at a first location, the first location being separated from the reference plane by the first predetermined distance, said step of jetting the at least one first ink drop comprising jetting the at least one first ink drop from the printhead firing plane onto said first ink drop sensor;
• and
• providing a second ink drop sensor at a second location, the second location being separated from the reference plane by the second predetermined distance, said step of jetting the at least one second ink drop comprising jetting the at least one second ink drop from the printhead firing plane onto said second ink drop sensor,
• wherein said first sensor includes two first terminals defining a first gap therebetween, said step of detecting the first ink drop including detecting a presence of ink in said first gap as a reduction in a first electrical resistance between said first terminals, said second sensor including two second terminals defining a second gap therebetween, said step of detecting the second ink drop including detecting a presence of ink in said second gap as a reduction in a second electrical resistance between said second terminals.

A method of determining a length of a printhead gap between a printhead and a print media surface plane in an ink jet printer, said method comprising the steps of:

• jetting a first ink drop from a printhead firing plane;
• detecting when the first ink drop is at a first location a first predetermined distance away from a reference plane;
• measuring a first time period between said jetting and said detecting of the first ink drop;
• jetting a second ink drop from the printhead firing plane;
• detecting when the second ink drop is at a second location a second predetermined distance away from the reference plane;
• measuring a second time period between said jetting and said detecting of the second ink drop;
• calculating an ink drop velocity by dividing a difference between the first predetermined distance and the second predetermined distance by a difference between the first time period and the second time period;
• determining a detecting distance by multiplying the ink drop velocity by the first time period;
• and
• ascertaining the length of the printhead gap by one of:
• subtracting a distance between the media surface plane and the first location from the detecting distance;
• and
• adding the distance between the media surface plane and the first location to the detecting distance.

An ink jet printer, comprising:

• a first sensor configured to detect a presence of a first ink drop at a first location;
• a second sensor configured to detect a presence of a second ink drop at a second location;
• and
• a processing device configured to calculate a speed of the first ink drop and the second ink drop in a jetting direction based on:
• a first time period between a printhead firing the first ink drop and said first sensor sensing the first ink drop;
• a second time period between said printhead firing the second ink drop and said second sensor sensing the second ink drop;
• and
• a distance between the first location and the second location in the jetting direction.

A method of determining an ink drop speed in a jetting direction in an ink jet printer, said method comprising the steps of:

• jetting a first ink drop in the jetting direction;
• detecting when the first ink drop is at a first location;
• measuring a first time period between said jetting and said detecting of the first ink drop;
• jetting a second ink drop in the jetting direction;
• detecting when the second ink drop is at a second location;
• measuring a second time period between said jetting and said detecting of the second ink drop;
• and
• calculating the ink drop speed dependent upon:
• the first time period;
• the second time period;
• and
• a distance between the first location and the second location in the jetting direction.

A method of determining a length of a printhead gap between a printhead and a print media surface plane in an ink jet printer, said method comprising the steps of:

• jetting a first ink drop from a printhead firing plane in a jetting direction;
• detecting when the first ink drop is at a first location;
• measuring a first time period between said jetting and said detecting of the first ink drop;
• jetting a second ink drop from the printhead firing plane in the jetting direction;
• detecting when the second ink drop is at a second location;
• measuring a second time period between said jetting and said detecting of the second ink drop;
• calculating an ink drop speed in the jetting direction by dividing a distance between the first location and the second location in the jetting direction by a difference between the first time period and the second time period;
• determining a detecting distance by multiplying the ink drop speed by the first time period;
• and
• ascertaining the length of the printhead gap by one of:
• subtracting a distance between the media surface plane and the first location from the detecting distance;
• and
• adding the distance between the media surface plane and the first location to the detecting distance.

A method of determining a printhead gap between a printhead and a first location in a jetting direction in an ink jet printer, said method comprising the steps of:

• jetting a first ink drop from the printhead in the jetting direction;
• detecting when the first ink drop is at the first location;
• measuring a first time period between said jetting and said detecting of the first ink drop;
• jetting a second ink drop from the printhead in the jetting direction;
• detecting when the second ink drop is at a second location;
• measuring a second time period between said jetting and said detecting of the second ink drop;
• and
• calculating the printhead gap dependent upon:
• the first time period;
• the second time period;
• and
• a distance between the first location and the second location in the jetting direction.

A method of determining an ink drop speed in a jetting direction in an ink jet printer, said method comprising the steps of:

• moving a printhead in a scanning direction;
• jetting a first ink drop in the jetting direction during said moving step;
• detecting when the first ink drop is at a first location;
• measuring a first distance traveled by the printhead between said jetting and said detecting of the first ink drop;
• moving the printhead in one of the scanning direction and a second direction substantially opposite to the scanning direction;
• jetting a second ink drop in the jetting direction during said second moving step;
• detecting when the second ink drop is at a second location;
• measuring a second distance traveled by the printhead between said jetting and said detecting of the second ink drop;
• and
• calculating the ink drop speed dependent upon:
• the first distance;
• the second distance;
• and
• a distance between the first location and the second location in the jetting direction.

A method of identifying an ink type in an ink jet printer, said method comprising the steps of:

• jetting ink onto a test surface providing a test pattern surface having a plurality of areas, selected nozzle of the ink jet printhead;
• emitting light onto the ink wherein the ink was actually jetted onto the test surface during said identifying step;
• measuring at least one characteristic of light reflected off of the ink;
• and
• determining the ink type based on the at least one characteristic of the respective area.

A method of detecting at least one missing nozzle in an ink jet printhead, said method comprising the steps of:

• attempting to jet ink onto a test surface with a selected nozzle of the ink jet printhead;
• using an optical device to detect whether the ink was actually jetted onto the test surface during said attempting step;
• and
• determining whether the selected nozzle is missing based upon a result of said detecting.

A method of detecting at least one missing nozzle in an ink jet printhead having a plurality of nozzles, said method comprising the steps of:

• providing a test surface having a plurality of areas, each of the areas corresponding to a respective one of the nozzles;
• attempting to jet ink onto each of the areas with the respective nozzles;
• using an optical device to detect whether the ink was actually jetted onto each of the areas during said attempting step;
• and
• determining whether at least one said nozzle is missing based upon a result of said detecting.

A method of detecting at least one missing nozzle in an ink jet printhead having a plurality of nozzles, said method comprising the steps of:

• providing a test surface have a predetermined region;
• using an optical detector to detect an intensity of light being one of reflected off of and emitted through the region;
• attempting to jet ink from one of the nozzles onto a respective area within the region;
• using said optical detector to detect a change in the intensity of light being one of reflected off of and emitted through the region, said light intensity change being a result of said attempting step;
• and
• determining whether said one nozzle is missing based upon the light intensity change.