Abstract: A liquid discharge apparatus includes a circulation channel in which liquid circulates, a liquid discharge head disposed on the circulation channel to discharge the liquid, a bypass channel to connect an upstream portion and a downstream portion of the liquid discharge head, a switch to switch the circulation channel between a first route in which the bypass channel is a part of the circulation channel and a second route in which the bypass channel is not a part of the circulation channel, a pressure generator to generate pressure to circulate the liquid in the circulation channel, a degassing device to degas the liquid in the circulation channel, and control circuitry to perform a degassing operation to degas the liquid by circulating the liquid in the circulation channel.

Abstract: An image forming apparatus includes a liquid discharge head, a temperature detector, a memory, and a controller. The temperature detector detects a temperature of the liquid discharge head. The memory stores the temperature of the liquid discharge head detected with the temperature detector. The controller controls a bubble purge operation to purge bubbles in the liquid discharge head. When a current temperature of the liquid discharge head acquired by the temperature detector is higher than a stored temperature stored in the memory and a deviation of the acquired current temperature and the stored temperature is equal to or more than a predefined threshold value, the controller executes control to execute the bubble purge operation, and when the current temperature acquired by the temperature detector is lower than the stored temperature, the controller executes control to update the stored temperature stored and retained in the memory with the acquired current temperature.

Abstract: An image forming apparatus includes a recording head, a head tank, a main tank, and a controller. The recording head includes nozzles to discharge liquid droplets. The head tank includes a liquid containing part to contain liquid supplied to the recording head. The main tank contains the liquid supplied to the head tank. The controller controls, after detection of an end state of the main tank, post-end printing using the liquid remaining in the head tank corresponding to the main tank in the end state. The controller permits the post-end printing when an amount of the liquid remaining in the head tank to which the liquid is supplied from the main tank in the end state is a predetermined threshold remaining amount or greater.

Abstract: An image forming apparatus includes a liquid discharge head, a temperature detector, a memory, and a controller. The temperature detector detects a temperature of the liquid discharge head. The memory stores the temperature of the liquid discharge head detected with the temperature detector. The controller controls a bubble purge operation to purge bubbles in the liquid discharge head. When a current temperature of the liquid discharge head acquired by the temperature detector is higher than a stored temperature stored in the memory and a deviation of the acquired current temperature and the stored temperature is equal to or more than a predefined threshold value, the controller executes control to execute the bubble purge operation, and when the current temperature acquired by the temperature detector is lower than the stored temperature, the controller executes control to update the stored temperature stored and retained in the memory with the acquired current temperature.

Abstract: An image forming apparatus includes a recording head, a head tank, a main tank, and a controller. The recording head includes nozzles to discharge liquid droplets. The head tank includes a liquid containing part to contain liquid supplied to the recording head. The main tank contains the liquid supplied to the head tank. The controller controls, after detection of an end state of the main tank, post-end printing using the liquid remaining in the head tank corresponding to the main tank in the end state. The controller permits the post-end printing when an amount of the liquid remaining in the head tank to which the liquid is supplied from the main tank in the end state is a predetermined threshold remaining amount or greater.

Abstract: An image forming apparatus includes a liquid ejection head, a cap, and a dummy discharge controller. The liquid ejection head has plural nozzle rows in a nozzle formed face thereof. Each of the plural nozzle rows includes multiple nozzles through which droplets are discharged. The cap caps the nozzle formed face of the liquid ejection head. The dummy discharge controller controls a dummy discharge operation to discharge dummy discharge droplets not contributing to image formation from the nozzles with the nozzle formed face opposed to the cap. The dummy discharge controller controls the liquid ejection head to discharge the dummy discharge droplets at different timings between adjacent nozzle rows of the plural nozzle rows in the dummy discharge operation.

Abstract: An image forming apparatus includes a liquid ejection head, a cap, and a dummy discharge controller. The liquid ejection head has plural nozzle rows in a nozzle formed face thereof. Each of the plural nozzle rows includes multiple nozzles through which droplets are discharged. The cap caps the nozzle formed face of the liquid ejection head. The dummy discharge controller controls a dummy discharge operation to discharge dummy discharge droplets not contributing to image formation from the nozzles with the nozzle formed face opposed to the cap. The dummy discharge controller controls the liquid ejection head to discharge the dummy discharge droplets at different timings between adjacent nozzle rows of the plural nozzle rows in the dummy discharge operation.

Abstract: An image forming apparatus includes a recording head, a head tank, a main tank, a liquid feed device, and a controller. When the main tank is in an ink end state, the controller causes the feed device to feed the liquid in reverse from the head tank to the main tank. When air is unlikely to be mixed with the liquid or the liquid is unlikely to be bubbled in the head tank before installation of a new main tank, the controller causes the feed device to feed the liquid from the main tank to the head tank with an air release unit opened after the installation. When air is likely to be mixed with the liquid or the liquid is likely to be bubbled in the head tank before the installation, the controller causes the feed device to feed the liquid with the release unit closed after the installation.

Abstract: An image forming apparatus includes a plurality of nozzles to discharge liquid droplets; a recording head including a pressure generator to generate a pressure to cause the nozzles to discharge liquid droplets; a droplet discharge status sensor unit to detect a droplet discharging status from each nozzle; and a maintenance controller to control a maintenance operation by a dummy discharge of liquid droplets not contributing to image formation. In such an image forming apparatus, the droplet discharge status sensor unit compares a detection result of the droplet discharge status and a preset reference threshold and determines whether the nozzle discharges normally or defectively; and the maintenance controller outputs a dummy discharge drive waveform corresponding to a difference between the detected droplet discharge status and the reference threshold to the pressure generator of the nozzle determined to be defective to cause the nozzle to discharge droplets for dummy discharging.

Abstract: An image forming apparatus includes a recording head, a head tank, a main tank, a liquid feed device, and a controller. When the main tank is in an ink end state, the controller causes the feed device to feed the liquid in reverse from the head tank to the main tank. When air is unlikely to be mixed with the liquid or the liquid is unlikely to be bubbled in the head tank before installation of a new main tank, the controller causes the feed device to feed the liquid from the main tank to the head tank with an air release unit opened after the installation. When air is likely to be mixed with the liquid or the liquid is likely to be bubbled in the head tank before the installation, the controller causes the feed device to feed the liquid with the release unit closed after the installation.

Abstract: An image forming apparatus includes a plurality of nozzles to discharge liquid droplets; a recording head including a pressure generator to generate a pressure to cause the nozzles to discharge liquid droplets; a droplet discharge status sensor unit to detect a droplet discharging status from each nozzle; and a maintenance controller to control a maintenance operation by a dummy discharge of liquid droplets not contributing to image formation. In such an image forming apparatus, the droplet discharge status sensor unit compares a detection result of the droplet discharge status and a preset reference threshold and determines whether the nozzle discharges normally or defectively; and the maintenance controller outputs a dummy discharge drive waveform corresponding to a difference between the detected droplet discharge status and the reference threshold to the pressure generator of the nozzle determined to be defective to cause the nozzle to discharge droplets for dummy discharging.