Method and apparatus for dispensing material in a printer

A printer for printing a viscous material at predetermined positions forming a pattern on a substrate, the printer comprising:

• a frame;
• a device, mounted to the frame, having a number of perforations arranged to form the pattern;
• a support apparatus, coupled to the frame, that supports the substrate in a printing position beneath the device;
• a material dispenser having a rigid chamber to contain the viscous material to be printed on the substrate, the chamber having an opening through which the viscous material is dispensed, the material dispenser being coupled to the frame, positioned over the device, and constructed and arranged to dispense the viscous material through the perforations in the device and onto the substrate;
• means for retaining the viscous material in the chamber after dispensing is complete including means for increasing a volume of the rigid chamber,
• a cartridge coupled to the chamber that provides material to the chamber;
• and
• means for applying pressure to the viscous material in the cartridge to force material from the cartridge into the chamber and out of the opening of the chamber.

A method for printing a pattern of viscous material on a substrate using a dispenser having a rigid chamber with an inlet to receive visous material and an outlet from which viscous material is dispensed, the chamber having a volume, the method comprising steps of:

• positioning the dispenser over the substrate;
• extending a plunger into the chamber to contact the material in the chamber and decrease the effective volume of the chamber;
• applying pressure to the viscous material in the chamber to dispense viscous material form the outlet of the chamber onto the substrate;
• relieving the pressure applied to the viscous material to discontinue dispensing;
• expanding the volume of the chamber to retain the viscous material in the chamber by at least partially retracting the plunger form the chamber;
• coupled a removable cartridge containing the viscous material in the chamber by at an outlet of the removable cartridge is coupled to the inlet of the chamber.

A system for depositing a viscous material at predetermined position forming a pattern on a substrate, the system comprising:

• a frame;
• a device, mounted to the frame, having a number of perforations arranged to form the pattern;
• a support apparatus, coupled to the frame, that supports the substrate in a printing position beneath the device;
• and
• a material dispenser coupled to the frame and including:
• a chamber to contain the viscous material to be printed on the substrate, the chamber having an opening through which the viscous material is dispensed onto the substrate;
• a retraction device, extendable into the chamber, that prevents leakage of the viscous material from the opening after dispensing is complete, the retraction device increasing the volume of the chamber after dispensing;
• a cartridge coupled to the chamber and containing material to be dispensed, the cartridge having an inlet to receive pressurized air to force the material from the cartridge into the chamber and out of the opening of the chamber.