Brother Kogyo Kabushiki-kaisha

Shiro Ueno

Katsumi Inukai

Masahito Hamaya

Hideki Arimoto

Hiroyuki Naganawa

A switched-mode power supply includes a transformer, a switching element, a switching controller, a voltage generator circuit, an overvoltage protection circuit, and a load increase circuit. The overvoltage protection circuit is configured to, when a first DC voltage outputted from the voltage generator circuit is below a predetermined voltage, apply a first drive voltage to an input terminal of the switching controller, and to, when the first DC voltage exceeds the predetermined voltage, apply a second drive voltage, which is different from the first drive voltage, to the input terminal, whereby the switching controller stops controlling switching operation. The load increase circuit is configured to, when the output voltage exceeds a threshold voltage, flow a current from the secondary side, thereby increasing a load applied to the secondary side. The threshold voltage is less than a rated voltage of the transformer and greater than the target voltage.

Switched-mode power supply having a load increase circuit

A switching power supply includes: a transformer; a switching device, which is connected to a primary coil of the transformer; a switching controller; a voltage generation circuit, which rectifies and smooths an AC voltage induced in an auxiliary coil provided on the primary side of the transformer, and output the rectified and smoothed AC voltage as a first DC voltage; and an overvoltage protection circuit, wherein the auxiliary coil and the switching controller are connected via a capacitor, and the switching controller stops the switching control depending on a change in at least one of a current and a voltage between electrodes of the capacitor, the change being caused by a voltage rise of the AC voltage induced in the auxiliary coil.

Switching power supply

An image forming apparatus, comprising: a frame body to which an attachment unit is detachably attachable, the attachment unit being configured to have an input electrode and to be used for image formation on a recording medium; a power source substrate configured to have an output electrode for outputting a voltage and to be attached to the frame body from an opposite side with respect to a side on which the attachment unit is attached; and a connection electrode configured to electrically connect the output electrode to the input electrode of the attachment unit, wherein the frame body comprises an insertion part into which the connection electrode is inserted from an opposite side with respect to a side on which the power source substrate is attached.

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Ichinomiya, Japan

Shiro Ueno