Patent Document ID: 9134675
Application ID: 13929748
Patent Flag: 1

Claim One:
1. An image production device, comprising: at least one replaceable cartridge; monitoring device in the at least one replaceable cartridge that monitors toner level changes; and a consumable management unit in communication with the at least one replaceable cartridge that determines from the toner level changes if a remaining useful life span is greater than a predetermined threshold, the predetermined threshold relating to the expected life span of the at least one replaceable cartridge; wherein if the consumable management unit determines that the remaining useful life span is not greater than the predetermined threshold, the consumable management unit automatically generating a message to a user at a user interface or to the consumable service/maintenance provider to replenish the at least one replaceable cartridge; wherein the remaining useful life span is determined by using the following equation: X 2 = ∑ t = 1 n ⁢ ⁢ W i ⁡ ( Y i - a - bx i ) 2 where y i is the toner level, x i is number of usage days, w i is a weight associated with the ith experiment and where a and b are the coefficients of a fitted linear line.