| 摘要 |
The invention discloses a system and method for sensing changes in the weight of an ink reservoir which supplies ink to a printhead which ejects ink onto a recording medium during a printer operational mode. The ink reservoir, whether located separately from the printhead, as in a plotter or pagewidth printer embodiment, or mechanically attached to the printhead and moved in a scanning printhead architecture, has its weight supported by a structure. A strain gage or other weight sensor is affixed to the supporting structure and incorporated in a circuit which produces an output signal representative of resistive changes in the weight sensor. Since a resistive change in the weight sensor is caused by a decrease in the supply of ink in the reservoir during continued printer operation, the output signal is proportional to the ink level. The output signal is digitized and sent to a system controller where it is compared to a predetermined reference level and a low level output signal is generated for use as a warning to a operator or user. In one embodiment, the strain gage is a leg of a resistor in a bridge circuit and provides continuous ink level readout. In another embodiment, multiple warning levels are enabled by inserting the resistor in a circuit where comparators compare the resistance of the strain gage to reference resistance levels.
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