Provided is a method for removing a first holder member from a second holder member in a cartridge. The cartridge includes: a housing; the first holder member holding an electrical contact surface; and the second holder member supported by the housing. The first holder member includes a pawl, and the second holder member includes a corner part engageable with the pawl of the first holder member. The electrical contact surface is held at one end surface of the first holder member in a first direction crossing the electrical contact surface. The method includes: disengaging the pawl from the corner part; and separating the housing and the second holder member from the first holder member in the first direction away from the one end surface of the first holder member.

An image forming apparatus includes a developing cartridge, a main memory and a controller. The controller is configured to perform determining whether the developing cartridge is reached a lifetime on a basis of: at least one of s developing maximum printable number of sheets which corresponds to developing identification information, a maximum developing roller rotation number which corresponds to the developing identification information, and a maximum dot count which corresponds to the developing identification information; and at least one of a developing cumulative number of printed sheets, a cumulative developing roller rotation number and a cumulative dot count.

A drum unit includes a photosensitive drum, a developing unit, a toner cartridge, a connector and a relay board. The photosensitive drum is rotatable about a first axis extending in an axial direction. The developing unit includes a magnetic roller, a developer container, a conveyer member and a toner sensor. The developer container accommodates therein carrier, and has an inlet. The conveyer member is positioned in the developer container, and configured to convey toner and the carrier from the inlet toward the magnetic roller. The toner cartridge accommodates therein toner and is attachable to the developer container to replenish toner in the developer container through the inlet. The connector is electrically connected to an image forming apparatus. The relay board electrically connects the toner sensor to the connector. The relay board is configured to transmit a detection signal from the toner sensor to the image forming apparatus.

An example print device may comprise a consumable component comprising a human-indiscernible hardware-based identifier. The example print device may also comprise a sensor to read the human-indiscernible hardware-based identifier.

An image forming apparatus includes a drum cartridge and a controller. The drum cartridge includes a photosensitive drum, a charger and a drum cartridge memory storing a life count value and discharge history information. The controller includes a voltage applying circuit, and an abnormal discharge detection circuit. In a case where the abnormal discharge detection circuit detects an abnormal discharge, the controller does not permit printing in a case where the life count value is equal to or more than a first reference value and a number of abnormal discharges which is included in the discharge history information read from the drum cartridge memory is equal to or more than a particular threshold value, or permits printing in a case where the life count value is equal to or more than the first reference value and the number of abnormal discharges is less than the particular threshold value.

A drum unit includes a photosensitive drum, a developing unit, a toner cartridge, a connector and a relay board. The photosensitive drum is rotatable about a first axis extending in an axial direction. The developing unit includes a magnetic roller, a developer container, a conveyer member and a toner sensor. The developer container accommodate therein carrier, and has an inlet. The conveyer member is positioned in the developer container, and configured to convey the toner and the carrier from the inlet toward the magnetic roller. The toner cartridge accommodate therein toner and is attachable to the developer container to replenish the toner in the developer container through the inlet. The connector is electrically connected to the image forming apparatus. The relay board electrically connects the toner sensor to the connector. The relay board is configured to transmit a detection signal from the toner sensor to the image forming apparatus.

The image forming apparatus includes a user interface, a controller, and a main memory. The controller provides an error notification to the user interface in a case where drum cartridge information read from the main memory does not match drum-cartridge identification information stored in a drum-cartridge memory of a drum cartridge and replacement of the drum cartridge replacement is not necessary. The controller may also provide an error notification to the user interface in a case where a toner cartridge information read from the main memory does not match toner-cartridge identification information stored in a toner-cartridge memory of a toner cartridge and replacement of the toner cartridge is not necessary.

An image forming apparatus includes a drum cartridge and a controller. The drum cartridge includes a photosensitive drum, a charger and a drum cartridge memory storing a life count value and discharge history information. The controller includes a voltage applying circuit, and an abnormal discharge detection circuit. In a case where the abnormal discharge detection circuit detects an abnormal discharge, the controller does not permit printing in a case where the life count value is equal to or more than a first reference value and a number of abnormal discharges which is included in the discharge history information read from the drum cartridge memory is equal to or more than a particular threshold value, or permits printing in a case where the life count value is equal to or more than the first reference value and the number of abnormal discharges is less than the particular threshold value.

An image forming apparatus includes an apparatus body, a cover, a cartridge, and a controller. The cartridge includes a second memory storing lifetime information indicating lifetime of the cartridge and identification information unique to the cartridge. In a case where the lifetime information indicates the initial value for the lifetime, the controller is configured to perform setting the cartridge to be usable in the image forming apparatus. In a case where the controller determines that the lifetime information does not indicate the initial value for the lifetime of the cartridge, the controller is configured to perform judging whether the identification information stored in the second memory matches a registration identification information stored in a first memory of the apparatus body. In a case where the identification information matches the registration identification information, the controller is configured to perform determining that the cartridge is usable for the image forming apparatus.

An image forming apparatus includes: a casing having an opening; a cover for opening and closing the opening; a cartridge attachable to the casing through the opening; and a controller. The casing includes a first memory. The cartridge includes a second memory storing consumption state information representing a consumption state of the cartridge. The controller performs: determining whether the cartridge attached to the casing is unused; storing, when the attached cartridge is unused, the consumption state information acquired from the second memory in the first memory; determining, when the image forming apparatus is powered on or the cover is closed, whether the consumption state information in the first memory and the consumption state information in the second memory match; permitting use of the cartridge when the two sets of consumption state information match; and prohibiting use of the cartridge when the two set of consumption state information does not match.