Ricoh Company, Ltd.

Jyunya Sakuraba

Kenji Sugiura

Naohiro Kumagai

Junpei Fujita

Seiichi Kogure

Kazuki Yogosawa

Yuuji Wada

Shinya Tanaka

Hirokazu Ishii

Hiroyoshi Haga

Masayoshi Nakayama

Toshitaka Yamaguchi

Tatsuya Ohsugi

Masahide Nakaya

Shinji Minami

Yuuto Hakamada

Hiroju Takanezawa

An image forming apparatus includes a photoconductor, a power supply, and circuitry. The power supply is configured to apply a charging voltage to the photoconductor. The circuitry is configured to control film thickness detection of detecting a charging current corresponding to the charging voltage to detect a film thickness of a surface of the photoconductor. The circuitry is further configured to determine a sampling period taken to detect the charging current; calculate a variation in the charging current detected; and determine whether the variation is greater than a threshold. The circuitry is configured to: determine the sampling period according to a determination result as to whether the variation is greater than the threshold; and sample the charging current for the sampling period determined, on a subsequent film thickness detection control.

Image forming apparatus and control method for controlling photoconductor film thickness detection

An image forming apparatus includes an image bearer including a first image portion to bear a first toner image, a second image portion to bear a second toner image, and a non-image portion to bear an adjustment pattern. A transferor forms a transfer nip with the image bearer. A controller controls the power source to output an image bias as a transfer bias to transfer the first toner image and the second toner image onto a first recording medium and a second recording medium, respectively, in the transfer nip when the first image portion and the second image portion pass through the transfer nip and output a non-image bias as the transfer bias when the non-image portion passes through the transfer nip. The controller performs a constant current control on the image bias and performs a constant voltage control when the image bias switches to the non-image bias.

Image forming apparatus

An image forming apparatus includes an image bearer, a transfer member, and a power source. The image bearer includes a plurality of layers. The transfer member forms a transfer nip between the image bearer and the transfer member. The power source outputs a transfer bias to transfer a toner image from the image bearer onto a recording sheet in the transfer nip. The transfer bias alternates between a transfer-side bias that causes the toner image to move from the image bearer to the recording sheet, and an opposite-side bias different from the transfer-side bias. A duty ratio of a time period, during which the opposite-side bias is output, relative to one cycle of a waveform, is greater than 50%.

A power supply controlling device includes: a direct-current power supply configured to output a direct-current voltage; an alternating-current power supply configured to output one selected from between a superimposed voltage obtained by superimposing an alternating-current voltage onto the direct-current voltage and the direct-current voltage; a bypass capacitor configured to partially store therein an output from the alternating-current power supply and configured to, when the direct-current voltage is output from the direct-current power supply while no electric charge is stored therein, store therein a second direct current being a part of a first direct current output from the direct-current power supply in conjunction with the output of the direct-current voltage; and a power supply controlling unit configured to cause the direct-current power supply to control a level of the direct-current voltage based on a target value for the first direct current and a value indicating the second direct current.

Power supply controlling device, power supply device, image forming apparatus, and power supply controlling method

In an embodiment, a fixing device includes: a fixing member that revolves in a circumferential direction in a heated state and transfers heat to a recording medium that is brought into contact with an outer circumferential face thereof; a temperature detecting unit that detects a temperature of the outer circumferential face of the fixing member; and a circumferential-direction position adjusting unit that adjusts a circumferential-direction position of the fixing member such that the recording medium is brought into contact with a high temperature portion out of the high-temperature portion of the outer circumferential face of the fixing member of which temperature detected by the temperature detecting unit is relatively high and a low-temperature portion of which temperature detected by the temperature detecting unit is relatively low.

Fixing device, image forming apparatus, and method of controlling fixing device

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Kanagawa, Japan

Jyunya Sakuraba