An image forming apparatus includes an apparatus body, an image bearing member, and a process unit attached to the apparatus body, the process unit including a frame including a storage portion configured to store developer, a developer bearing member configured to supply developer to the image bearing member to develop an electrostatic latent image; and a circuit board attached to the frame, wherein the circuit board includes a light emitting portion configured to emit light, and a light receiving portion configured to receive the light emitted from the light emitting portion and having passed through an interior of the storage portion.

A toner collection container detachably incorporated in an electrophotographic image forming device in order to collect toner to be discarded from an image former of the device includes: a housing including a hollow capable of storing discarded toner, and incorporated between an air inlet port and the image former in a space surrounded by a chassis of the image forming device; and at least one duct being formed of a cylindrical or tubular member that penetrates a storing region in the hollow of the housing from a side closer to the air inlet port to a side closer to the image former out of side walls of the housing, or formed of a recess included in a bottom surface of the housing and recessed toward the storing region, the duct guiding external air flowing from the air inlet port to a side where the image former is positioned.

An image forming apparatus includes a controller configured to, each time a development roller of a developing device rotates by a particular rotational amount, increment a counter value stored in a storage, calculate a remaining amount of developer in the developing device, when the counter value is less than a first value, setting a remaining amount threshold to a first threshold, whereas, when the counter value is equal to or more than a second value, setting the remaining amount threshold to a second threshold, the second value being equal to or more than the first value, the second threshold being less than the first threshold, and when the calculated remaining amount is less than the set remaining amount threshold, control a transporter to transport developer stored in a developer box to the developing device.

A toner collection container detachably incorporated in an electrophotographic image forming device in order to collect toner to be discarded from an image former of the device includes: a housing including a hollow capable of storing discarded toner, and incorporated between an air inlet port and the image former in a space surrounded by a chassis of the image forming device; and at least one duct being formed of a cylindrical or tubular member that penetrates a storing region in the hollow of the housing from a side closer to the air inlet port to a side closer to the image former out of side walls of the housing, or formed of a recess included in a bottom surface of the housing and recessed toward the storing region, the duct guiding external air flowing from the air inlet port to a side where the image former is positioned.

An image forming apparatus includes a controller configured to, each time a development roller of a developing device rotates by a particular rotational amount, increment a counter value stored in a storage, calculate a remaining amount of developer in the developing device, when the counter value is less than a first value, setting a remaining amount threshold to a first threshold, whereas, when the counter value is equal to or more than a second value, setting the remaining amount threshold to a second threshold, the second value being equal to or more than the first value, the second threshold being less than the first threshold, and when the calculated remaining amount is less than the set remaining amount threshold, control a transporter to transport developer stored in a developer box to the developing device.

A developing device includes a developer storage chamber configured to store developer to be supplied to the development chamber, a partition configured to separate a development chamber and the developer storage chamber and having an opening allowing communication between the developer storage chamber and the development chamber, and a protruding portion configured to protrude toward the inside of the developer storage chamber from the partition on a downstream side of the opening in the rotation direction of a rotating shaft, and within one turn of rotation of the rotating shaft, a receiving member moves while contacting the protruding portion according to the rotation of the rotating shaft.

An electrophotographic image forming apparatus may include an imaging cartridge and a toner cartridge that are detachably attached to a main body, a first optical sensor that is mounted in the imaging cartridge and detects a toner level in a development chamber, and a second optical sensor that is mounted in the toner cartridge and detects a toner level in the development chamber.

A developing device includes a developer storage chamber configured to store developer to be supplied to the development chamber, a partition configured to separate a development chamber and the developer storage chamber and having an opening allowing communication between the developer storage chamber and the development chamber, and a protruding portion configured to protrude toward the inside of the developer storage chamber from the partition on a downstream side of the opening in the rotation direction of a rotating shaft, and within one turn of rotation of the rotating shaft, a receiving member moves while contacting the protruding portion according to the rotation of the rotating shaft.

An electrophotographic imaging system according to one example embodiment includes a toner cartridge including a housing having a reservoir for storing toner. A shaft is rotatably positioned within the reservoir and includes a threaded portion. A partition mounted on the threaded portion of the shaft moves axially along the threaded portion when the shaft rotates. The partition divides the reservoir into a first toner compartment and a second toner compartment. A sensing arrangement monitors an axial position of the partition along the shaft. The sensing arrangement includes a plurality of sensors arranged at predetermined axial locations relative to the shaft and a sensed member connected to the partition. The plurality of sensors are positioned to detect an axial position of the sensed member relative to the shaft for determining the axial position of the partition along the shaft.

A developing device includes a developer storage chamber configured to store developer to be supplied to the development chamber, a partition configured to separate a development chamber and the developer storage chamber and having an opening allowing communication between the developer storage chamber and the development chamber, and a protruding portion configured to protrude toward the inside of the developer storage chamber from the partition on a downstream side of the opening in the rotation direction of a rotating shaft, and within one turn of rotation of the rotating shaft, a receiving member moves while contacting the protruding portion according to the rotation of the rotating shaft.