A print apparatus is disclosed. The print apparatus comprises a container-receiving unit for receiving a reusable print agent container; a print agent reservoir for storing print agent to be consumed by the print apparatus during a printing operation; a pump for transferring print agent between a reusable print agent container positioned in the container-receiving unit and the print agent reservoir; and processing circuitry. The processing circuitry is to operate the pump to transfer print agent of a first concentration from the reusable print agent container to the print agent reservoir; and, responsive to determining that a volume of print agent of the first concentration in the reusable print agent container has fallen below a threshold volume, operate the pump to transfer a volume of print agent of a second, lower concentration from the print agent reservoir to the reusable print agent container. A method and a machine-readable medium are also disclosed.

A toner transport apparatus includes: a storing portion that stores toner used by a developing apparatus; an ejection port for outputting the toner from the storing portion; a transport path unit that includes a receiving part which receives the toner ejected from the ejection port, and that constitutes a transport path for transporting the toner to the developing apparatus; a pump for outputting the toner stored in the storing portion from the ejection port toward the transport path unit; and an optical sensor unit that is disposed in a passage area through which the toner output by the pump from the ejection port to the transport path unit passes, the optical sensor unit detecting whether or not toner is present.

A print agent vessel is disclosed that comprises a circuit, the circuit comprising a first electrically conductive portion to couple to a first terminal of a printing device, a second electrically conductive portion to couple to a second terminal of the printing device, and an electrically conductive component capacitively coupled to the first electrically conductive portion. The circuit has a variable capacitance that is indicative of a parameter of the component.

A replaceable print component is disclosed that comprises first and second electrodes, and a circuit electrically connected between the first and second electrodes to vary an electrical property of the circuit with a frequency component within a selected frequency range to indicate a parameter of a part of the circuit in response to a stimulus.

Example aspects described herein relate to an apparatus for adjusting control parameters of a printing substance for a printing system. Such adjustments may occur in conjunction with a color calibration process of the printing system.

In an example, a method includes providing a print agent with chargeable particles in a carrier fluid to a print agent concentration apparatus. The print agent may be passed between a conveyor and an electrode, and a potential applied to cause the chargeable particles to be attracted to the conveyor and to form a concentrated layer of particles on the conveyor. An indicator of particle concentration in the concentrated layer may be measured. It may be determined if the indicator of particle concentration meets predetermined criteria.

In one example of the disclosure, a first measurement of actual quantity of ink in a target cartridge is taken utilizing a scale. An incremental dosage quantity be deposited into the target cartridge in a dosing pass is determined based upon a desired quantity, the actual quantity, and an undershoot safety factor. A valve is opened to enable a pressure deposit of the incremental dosage quantity of ink to the target cartridge, and then closed. A residue cutter is utilized to scrape the valve and thereby make a scraper deposit of ink to the target cartridge. A second measurement of actual quantity of ink in the target cartridge is taken utilizing the scale. An additional dosage pass is performed if the second measurement is not within an accepted variance of the desired quantity. The making of dosing passes is discontinued if the second measurement is within the accepted variance.

In an image forming apparatus, in a case where a power of the apparatus is turned from OFF to ON, a rotation drive unit rotationally drives each of a developing roller, a first conductive roller, and a second conductive roller in a state where a liquid developer supplied to a developer container by a supply device has reached a supply position, and a bias application unit applies a bias to each of the developing roller, the first conductive roller, and the second conductive roller after the developing roller rotates at least once, in the state where the liquid developer supplied to the developer container by the supply device has reached the supply position.

In an example, charged particles suspended in a non-conductive fluid are fed to a transfer device. A width of a charged particles layer of uniform density on a surface of the transfer device is controlled. Charged particles are transferred from the charged particles layer to a photo imaging plate of a liquid electro-photographic printing system.

An image forming apparatus includes a controller for performing a mode, in which an image portion potential is controlled during image formation so that an absolute value of the image portion potential is a first value when a resistance value of a developing roller based on a value of a current flowing between the developing roller and an electroconductive member is smaller than a predetermined value when a predetermined potential difference between the developing roller and the electroconductive member is formed during non-image formation and so that an absolute value of the image portion potential is a second value smaller than the first value when a resistance value of the developing roller based on a value of current flowing between the developing roller and the electroconductive member is not smaller than the predetermined value when the predetermined potential difference between the developing roller and the electroconductive member is formed during non-image formation.