Canon Kabushiki Kaisha

Adeka Corporation

Yuta Okuyama

Tomoyuki Sakamaki

Yusuke Ishida

Katsuya Nose

Takanori Iida

Masashi Wakisaka

Yoshie Makabe

A developing device includes a developer bearing member and carrier to develop an electrostatic latent image formed on an image bearing member, a developing container, a conveying screw which conveys the developer, and an inductance sensor which includes a detecting portion which detects magnetic permeability of the developer in the developing container. If the inductance sensor is not attached to the developing container and a predetermined magnetic material is disposed in contact with the detection portion, an output value when the detecting portion detects magnetic permeability of the predetermined magnetic material is A, and if the inductance sensor is not attached to the developing container and the predetermined magnetic material is disposed 1 mm away from the detection portion in a vertical direction passing through the detection portion, an output value when the detecting portion detects magnetic permeability of the predetermined magnetic material is B, with B/A≥0.1 being satisfied.

Developing device having inductance sensor

In a developing apparatus, a distance along an outer peripheral surface of a rotatable developing member between a first and a second maximum peak positions is less than 18 [mm], the first and the second maximum peak positions respectively corresponding to maximum values of a magnetic flux density of a first and a second magnetic poles with respect to a normal direction of the rotatable developing member. A distance along the outer peripheral surface of the rotatable developing member in a width of a value obtained by adding 2 [mT] to a minimum value of the magnetic flux density with respect to the normal direction of the rotatable developing member is 5.5 [mm] or more, at a downstream side of the first maximum peak position and at an upstream side of the second maximum peak position with respect to a rotation direction of the rotatable developing member.

Developing apparatus capable of enhancing efficiency of peeling off developer from a developing sleeve

An image forming apparatus includes an image bearing member, an exposure device configured to expose the image bearing member to form an electrostatic latent image thereon, and a developing device including a rotatable developing member configured to carry and feed a developer containing toner and a carrier to develop the electrostatic latent image formed on the image bearing member, and a magnet provided non-rotatably and stationarily inside the rotatable developing member including a developing magnetic pole, wherein magnetic chains formed by the carrier, on the rotatable developing member, magnetized by the magnet contact the electrostatic latent image formed on the image bearing member in a developing region of the rotatable developing member, wherein a maximum peak position where a magnetic flux density of the developing magnetic pole is maximum with respect to a normal direction of the rotatable developing member exists within a range of the developing region with respect to a rotational direction of the rotatable developing member, and wherein a ratio of an 80%-value-width which is a width of a portion where the magnetic flux density of the developing magnetic pole with respect to the normal direction of the rotatable developing member is 80% of the maximum of the magnetic flux density of the developing magnetic pole with respect to the normal direction of the rotatable developing member to a half peak width which is a width of a portion where the magnetic flux density of the developing magnetic pole with respect to the normal direction of the rotatable developing member is half of the maximum of the magnetic flux density of the developing magnetic pole with respect to the normal direction of the rotatable developing member is 0.65 or more.

Developing device

An image forming apparatus includes a permeability sensor configured to detect information on magnetic permeability of developer contained in a developer container for detecting toner density of the developer, and a controller configured to control a control voltage applied to the permeability sensor so that (i) a value of the control voltage that is applied to the permeability sensor in a case where a predetermined condition including a condition that the toner density of the developer contained in the developer container is a predetermined density is satisfied and an amount of the developer contained in the developer container is a first amount is greater than (ii) a value of the control voltage applied to the permeability sensor in a case where the predetermined condition is satisfied and the amount of the developer contained in the developer container is a second amount greater than the first amount.

Image forming apparatus having toner density control

An image forming apparatus includes a control portion, and in a first period from when use of a developing apparatus is started until when an amount of developer in a developing device reaches a predetermined amount larger than an amount of initial developer, when an amount of developer supplied from a supplying portion through a single supplying operation in an image forming operation is larger than a predetermined supplied amount, the control portion interrupts the image forming operation and drives a conveyance portion for a predetermined time. In a second period after the amount of the developer reaches the predetermined amount, when an amount of the supplying developer supplied through a single supplying operation in the image forming operation is larger than the predetermined supplied amount, the control portion continues the image forming operation without interruption.

Image forming apparatus having image formation interruption

A developing device includes a rotatable developing sleeve to carry and feed a developer including toner and a carrier toward a developing region, and a magnetic field generating portion provided inside the developing sleeve and having a developing magnetic pole for forming the developing region. The developing magnetic pole is disposed opposite to a closest position of the image bearing member to the developing sleeve. A ratio of an 80%-value-width of magnetic flux density of the developing magnetic pole with respect to a normal direction of the developing sleeve to a half peak width of the magnetic flux density of the developing magnetic pole with respect to the normal direction is 0.65 or more.

A developing device includes a developing sleeve configured to carry and convey developer containing non-magnetic toner and magnetic carrier and having a plurality of concave parts on a surface thereof. The concave parts are periodically arranged in each of a rotation direction and a width direction of the developing sleeve, and each have a shape that can house a circular shape having a diameter equal to an average particle diameter of the carrier carried on the developing sleeve, in a planar view. A distance between the concave parts is smaller than the average particle diameter.

A groove is provided in a magnet such that a first magnetic force region where an absolute value of a magnetic force of a component in a direction normal to a developer carrying member is 1 [nN] or less is formed on a surface of the developer carrying member on a downstream side of a third maximum peak position and on an upstream side of a second maximum peak position in a rotation direction of the developer carrying member, and a second magnetic force region where the absolute value of the magnetic force of the component in the direction normal to the developer carrying member is 1 [nN] or less is formed on the surface of the developer carrying member on a downstream side of a first maximum peak position and on an upstream side of the third maximum peak position in the rotation direction of the developer carrying member.

Developing device and magnet for two-component development

A development device includes a magnetic field generation unit having a developing magnetic pole S, a magnetic pole N, and a magnetic pole N. The magnetic poles Nand Nare disposed adjacent to the magnetic pole S, at positions downstream and upstream of the magnetic pole Sin a rotation direction of a sleeve, respectively. The magnetic pole Nis configured to have a larger magnetic flux density and full width half maximum in a normal direction of the sleeve and have a smaller inter-pole distance from the developing magnetic pole than the magnetic pole N, so that the rising position of magnetic brushes of developer is shifted in the upstream direction, and the magnetic brushes come into contact with a photosensitive drum more suitably.

Development device using a dry electrophotographic method

An image forming apparatus includes an image bearing member, a developing device which is configured to store developer having magnetic carrier and toner and to develop an electrostatic latent image formed on the image bearing member, and a discharge port which is arranged in the developing device and through which developer is discharged from the developing device. A collection portion is configured to collect the developer discharged through the discharge port, and a discharge conveyance portion is configured to convey the developer discharged through the discharge port to the collection portion. An environment detector is arranged in a conveyance passage of the discharge conveyance portion and is configured to detect environment information, and an adjustment portion is configured to adjust a development condition of the developing device based on output of the environment detector.

Image forming apparatus

Disclosed are a photo-acid generator having high developing properties, a cationic polymerization initiator having high curing properties, and a resist composition and a cationically polymerizable composition containing the photo-acid generator and the cationic polymerization initiator, respectively. Described are a noble aromatic sulfonium salt compound of general formula (I) and a photo-acid generator, a cationic polymerization initiator, a resist composition, and a cationically polymerizable composition containing the compound.  In formula (I), Rto Rare each an optionally substituted C1-C18 alkyl, etc.; Rto Rare each an optionally substituted C1-C18 alkyl, etc.; Ris an optionally substituted C1-C18 alkyl, etc.; and Xis a monovalent anion.

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Matsudo, Japan

Yuta Okuyama