Monitoring system with dual memory for electrophotographic printing machines using replaceable cartridges
AssigneeXerox Corporation
InventorChristian G. Midgley, Sr.
Life of this patent
Estimating the term…
Abstract
A monitoring system for replaceable units, such as toner cartridges in an electrophotographic printer, includes on the unit an electronic count memory and an electronic flag memory. The count memory maintains a one-by-one count of prints made with the cartridge. The flag memory includes a series of bits which are alterable from a first state to a second state but not alterable from the second state to the first state. The bits in the flag memory are altered at predetermined intervals as prints are made with the cartridge. The flag memory is used as a check to override unauthorized manipulation of the count memory.
Claims16
A replaceable unit relating to an output of a predetermined number of prints in an electrophotographic printer, comprising:
- a first memory, permanently associated with the replaceable unit, adapted to retain counting data relating to a cumulative output relating to the replaceable unit;
- and
- a second memory, permanently associated with the replaceable unit, having a plurality of flags associated therewith, each flag being statable in one of a first state and a second state, each flag being alterable from the first state to the second state but not alterable from the second state to the first state.
A monitoring system for a replaceable unit in an electrophotographic apparatus, the replaceable unit being adapted to relate to an output of a predetermined number of prints, comprising:
- a first memory, permanently associated with the replaceable unit, adapted to retain counting data relating to a cumulative output relating to the replaceable unit;
- a second memory, permanently associated with the replaceable unit, having a plurality of flags associated therewith, each flag being statable in one of a first state and a second state, each flag being alterable from the first state to the second state but not alterable from the second state to the first state;
- means for altering one flag in the second memory from the first state to the second state in response to a predetermined cumulative output relating to the replaceable unit;
- and
- means for comparing counting data in the first memory and the number of flags in a predetermined state in the second memory.
A method of monitoring a cumulative use of a replaceable unit relating to an output of a predetermined number of prints in an electrophotographic printer, comprising the steps of:
- changing a number stored in a first memory in accordance with the number of prints outputted;
- and
- altering one flag in a second memory from a first state to a second state when the predetermined number of prints are outputted, each flag in the second memory being selectably alterable from the first state to the second state but not alterable from the second state to the first state.
Dependencies are inferred from the claim text.