Canon Kabushiki Kaisha

Takahito Fuse

Tadashi Fukuda

Masami Hano

Shota Soda

Takehiro Kojima

Atsushi Matsumoto

Kenichiro Kitajima

Hidetaka Nakahara

Hiroyuki Amano

Tatsuya Kohno

Hiroaki Ishida

An image forming apparatus includes an image bearing member and a developer bearing member. A first period is from when rotational drive of the developer bearing member is started until increased to a speed at which the image forming apparatus performs image forming. A first absolute value of a difference between a developer bearing member surface potential Vdc and an image bearing member surface potential Vd, as determined when the image bearing member is facing the developer bearing member, is obtained during the first period. The value |Vdc−Vd| obtained during the first period is smaller than the value |Vdc−Vd| obtained after the first period. During the first period, the image bearing member surface potential Vd at the facing position is a first potential and, after the first period, the image bearing member surface potential Vd at the facing position becomes a second potential different from the first potential.

Image forming apparatus

An image forming apparatus includes a rotatable intermediate transfer member; a first image forming portion having a first photosensitive member which rotates, a first developing unit, and a first charge eliminating unit; a second image forming portion that is located on a downstream side of the first image forming portion in a rotational direction of the intermediate transfer member, and that has a second photosensitive member which rotates, a second developing unit, and a second charge eliminating unit; a transfer unit; and a switching unit that switches a light amount of the second charge eliminating unit when a usage amount of the second image forming portion reaches a predetermined amount to a value that is greater than a light amount of the first charge eliminating unit when a usage amount of the first image forming portion reaches the predetermined amount.

Image forming apparatus and image forming system

An image forming apparatus includes a photosensitive member, a first charging roller, a first cleaning member, a second charging roller, and a second cleaning member. The following relationship is satisfied:(0+1+2)&#x2212;(3+4)&#x2260;0where Lrepresents a length of a whole circumference of the first charging roller, Lrepresents a length between a first contact area and a first contact position of the first charging roller and the photosensitive member, Lrepresents a length of a whole circumference of the second charging roller, Lrepresents a length between a second contact area and a second contact position, Lrepresents a length between the first contact position and the second contact position, X represents an integer in a range of 0&#x2264;X&#x2264;40, and Y represents an integer in a range of 0&#x2264;Y&#x2264;40.

An image forming apparatus has a changing portion configured to change, based on a detection result of a temperature sensor, response sensitivity in starting of power supply by a determination portion based on a detection result of a human body detection sensor in a case where a human body approaches the human body detection sensor. The changing portion increases the sensitivity in a case where a temperature detected by the temperature sensor is a second temperature lower than a first temperature than in a case where the temperature detected by the temperature sensor is the first temperature.

An image forming apparatus including a rotatable photosensitive member, a first charging member for electrically charging the photosensitive member at a first charging portion by applying thereto a first DC voltage, and a second charging member, provided downstream of the first charging portion with respect to a rotational direction of the photosensitive member, for electrically charging the photosensitive member charged by the first charging member, at a second charging portion by applying thereto an oscillating voltage in the form of a second DC voltage superposed with an AC voltage. In addition, a toner image forming portion, provided downstream of the second charging portion and upstream of the first charging portion, forms a toner image on a surface of the charged photosensitive member, a current detecting portion detects a DC current passing through the second charging member, and a controller controls a voltage value of the first DC voltage on the basis of the detected DC current when the first DC voltage is applied to the first charging member and the oscillating voltage is applied to the second charging member. The controller controls the voltage value of the first DC voltage so that an absolute value of the detected DC current is smaller than a predetermined value.

Image forming apparatus having voltage control

A high-density area of a low-reflectance patch image is accurately detected. There is an image forming apparatus that detects the density of a patch image by radiating light from a laser oscillatorand receiving reflected light reflected off the patch image using a line sensor. The density of a black patch imagehaving a low reflectance is detected from the difference between the position at which reflected light from a yellow patch imageis received and the position at which reflected light from a superimposed toner image that is transferred in such a manner that the yellow patch imageis superimposed on the top of the black patch imageis received.

A toner image height measurement apparatus capable of accurately measuring heights of toner images of respective colors with a relatively simple construction and without being affected by toner colors. With motion of an image carrier, there occurs a change in reflection light amount detected by a photodiode of the height measurement apparatus in timing when laser light having been irradiated onto the image carrier starts to be irradiated onto or intercepted by a toner image and in timing when the laser light having been irradiated onto the toner image starts to be irradiated onto the image carrier. Based on a principle that these timings vary according to a toner image height, the height measurement apparatus detects the timing when the reflection light amount changes by a predetermined amount, thereby detecting the toner image height.

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Nagareyama, Japan

Takahito Fuse