Konica Minolta Business Technologies, Inc.

Konica Minolta, Inc.

Makiko Watanabe

Toshiya Natsuhara

Shigeo Uetake

Takeshi Maeyama

Junya Hirayama

Nofumi Mizumoto

Eiji Tabata

Keiko Momotani

Atsuto Hirai

Yuuya Sato

An image forming device includes: an endless intermediate transfer belt; and a secondary transferrer, wherein the secondary transferrer includes a secondary transfer roller and a counter roller, a value calculated from w/Vis defined as a nip time N [sec], when the secondary transferrer is deemed as an equivalent circuit including a resistance R1 [&#x3a9;&#xb7;m] of the secondary transfer roller, a resistance R2 [&#x3a9;&#xb7;m] of the intermediate transfer belt, a resistance R3 [&#x3a9;&#xb7;m] of the counter roller, and capacitance C[F/m] of a recording medium, in a case where a combined resistance in the equivalent circuit is defined as R[&#x3a9;&#xb7;m], and combined capacitance in the equivalent circuit is defined as C[F/m], a value calculated from R&#xd7;Cis defined as a time constant &#x3c4; [sec], and the image forming device further includes: a sheet detector; and a hardware processor.

Image forming device

Prevention of an image defect due to discharging in a transfer portion and ensured transfer efficiency are both achieved. A control electrode is in contact with an outer circumferential surface of a secondary transfer roller on an upstream side of a position of contact between the secondary transfer roller and a recording medium in a direction of rotation of the secondary transfer roller. The control electrode has a potential set to a repel a toner image with respect to the secondary transfer roller. The control electrode is in contact with the outer circumferential surface of the secondary transfer roller under such a condition that discharging occurs in a gap between the secondary transfer roller and the intermediate transfer belt and a discharging current flows through the recording medium.

Control electrode for image formation apparatus

A transfer belt includes: an elastic layer, wherein the transfer belt is used to transfer a toner image onto a recording medium, the toner image being carried on a first main surface which is one of a pair of main exposed surfaces including the first main surface and a second main surface, when, using a lower block and an upper block, the transfer belt is placed on an upper surface of the lower block, a part of the transfer belt is interposed between a curved convex surface and a curved concave surface, and a pressed region reaches a pressing force of 200 [kPa] and is constantly pressed by the pressing force, if 'a' represents a maximum value of displacement of a measurement region, and 'b' represents displacement of the measurement region after convergence, E [&#x2212;] calculated by (a&#x2212;b)/b satisfies a condition of 0.2&#x2264;E&#x2264;3.

Transfer belt and image forming device

A transfer belt transfers a toner image carried on a first main surface to a recording medium. When the transfer belt is pressed by using a lower block provided with a hole and an upper block with pressurization force increased at a prescribed rate and thereafter kept constant, E [-] and t0 are curve-fitted to a function E=&#x3b1;&#xd7;exp(&#x2212;t0/&#x3c4;) defined by a time constant &#x3c4; [s] with respect to an amount of displacement of the transfer belt and a constant &#x3b1; [-], where E [-] is calculated as (a&#x2212;b)/b, a [&#x3bc;m] represents a maximum value of an amount of displacement of a measurement region, b [&#x3bc;m] represents an amount of displacement of the measurement region after converged, and t0 [s] represents a time period from start of pressurization until the maximum pressurization force, and time constant &#x3c4; satisfies a condition of 0.015&#x2264;&#x3c4;&#x2264;0.1.

Transfer belt and image formation apparatus

A transfer belt is configured to transfer a toner image carried on a first main surface of the transfer belt to a recording medium. When the transfer belt is pressed with pressure application three increased at a predetermined pressure application rate and is then pressed with certain pressure application force by using a lower block provided with a hole and an upper block, k[&#x3bc;m/s] satisfies 6&#x2264;k&#x2264;30, k[&#x3bc;m/s] being determined by (a&#x2212;b)/{2&#xd7;(t&#x2212;t)}, where a [&#x3bc;m/s] represents a maximum value of a displacement amount of a measurement region that is a portion of the first main surface corresponding to the hole, b [&#x3bc;m] represents a convergence value thereof, t[s] represents a time when the maximum value is observed, and t[s] represents a time when the displacement amount reaches (a+b)/2 again after the maximum value is observed.

Transfer belt and image forming apparatus

In the present wet-type image formation apparatus, when setting a standard image formation condition, a control unit adjusts both a conveyance amount of toner and a charge amount of the toner in order to obtain a predetermined developing characteristic. During normal image formation, the control unit obtains the image density of a patch image formed at a high contrast potential and the image density of a patch image formed at a low contrast potential, adjusts the conveyance amount of the toner when the image density of the patch image formed at the high contrast potential is varied from the developing characteristic for the standard image formation condition, and adjusts the charge amount of the toner when the image density of the patch image formed at the low contrast potential is varied from the developing characteristic for the standard image formation condition.

Wet-type image formation apparatus adjusting toner conveyance amount and toner charge amount

When a toner charging amount for toner in a liquid developer conveyed to a development portion is set, a wet-type image formation apparatus performs a sensing operation in which a sensing unit senses image densities of a plurality of patch images formed at different development biases with the toner charging amount being set to a constant value, and a setting operation in which, in a case where a control unit calculates current development characteristics based on the image densities of the plurality of patch images sensed by the sensing unit, and determines that the current development characteristics are not included within a set target range, the control unit controls a charging unit to set the toner charging amount such that the development characteristics are included within the set target range.

Wet-type image formation apparatus

A development apparatus and an image forming apparatus wherein optical high-precision detection of the toner amount of a toner layer formed on a toner carrying member is ensured even when the great amount of the toner is deposited on the toner carrying member by transferring all or a part of the toner on the surface of the toner carrying member onto a detecting roller, and wherein stable images are provided at all times.

Development apparatus and image forming apparatus using the same

Provided is a deposited-toner measuring apparatus capable of accurate detection of the amount of toner deposited on the toner carrying member, and an image forming apparatus equipped with the aforementioned measuring apparatus and capable of controlling the amount of toner deposited on the toner carrying member to a desired level so as to provide stable image quality at all times. A deposited-toner measuring apparatus that removes a toner layer in a part of the surface of the toner carrying member, detects change in the capacitance at the portion with a toner layer and the portion without such a toner layer, and detects the amount of the deposited toner based on the detection result of the said change in the capacitance.

Deposited toner measuring apparatus having a capacitor and a capacitance change detector for detecting a change in capacitance of the capacitor, and an image formation apparatus, and method for controlling image formation apparatus related thereto

A developer device includes two developer rollers arranged opposite to an image carrier. A first developer bias voltage (waveform Z) of a rectangular waveform obtained by superimposing an AC voltage on a DC voltage is applied to one of the developer rollers. A second developer bias voltage (waveform A) obtained by superimposing an AC voltage on a DC voltage is applied to the other developer roller. The waveform A is a waveform obtained by deforming the rectangular wave in the first developer bias voltage such that toner adhered to the image carrier is prevented from being dislodged by toner being subsequently scattered. According to the developer device, an optimal image density can be obtained at a low-density potential.

Developer device and image forming apparatus

Provided is a development device and an image forming apparatus that realize high image quality with improved decrease in density at high speed development and with reduced occurrence of development hysteresis (ghost) in a hybrid developing method having a plurality of toner carriers, by reducing the decrease in the toner supplying ability to a downstream-side toner carrier, which decrease is caused by the supply of toner to an upstream-side toner carrier on an upstream side in a rotating direction of a developer carrier. By providing a magnetic pole between main magnetic poles, of the developer carrier, facing the toner carriers, a magnetically raised bristle of developer is moved by a magnetic force, while the developer in which development hysteresis due to supplying toner to the upstream-side toner carrier occurred is conveyed to supply toner to the downstream-side toner carrier, whereby a developer layer is stirred.

Development device having developer carrier with stationary disposed magnetic body

Provided are a development apparatus and an image forming apparatus which, in a hybrid development apparatus provided with a plurality of toner carriers, a toner supply capability to supply toner to each toner carrier is controlled independent of development electric fields between the toner carriers and an image carrier, whereby each toner carrier is allowed to exhibit a desired development capability, and even in the case of high speed development, a high quality image is provided. The phases, the frequencies, and/or the duty ratios of the alternating current components of the voltages applied to the plurality of the toner carriers are made to be different, whereby the toner supply amount for each toner carrier from the developer carrier is controlled independently of the development electric fields between the toner carriers and the image carrier.

Development apparatus and image forming apparatus

Provided is a development device and an image forming apparatus both using a hybrid development method and capable of forming high quality images without occurrence of development hysteresis (ghost). The nip portion of the toner carrier and the developer carrier is configured as follows: the rotating direction of a toner carrier and a developer carrier are in counter directions; a magnetic pole facing the toner carrier is positioned on the upstream side in the developer carrier rotating direction; and a counter charge generated by the toner supply reaches a toner recovering portion without being considerably attenuated.

Development device and image forming apparatus using the same

In a hybrid development method using a plurality of toner carriers, a development device and image forming apparatus are provided, wherein high image quality in which toner density is not reduced even in the case of high speed printing and the occurrence of development hysteresis (ghost) is controlled is ensured by accelerating the collection of the post-development residual toner on the toner carrier. The counter-charge having occurred in the developer remains in the developer without decreasing to disappear until the developer moves to the second toner carrier on the downstream-side, wherein this counter-charge is caused by supplying toner to the first toner carrier upstream in the rotating direction of the developer carrier.

Provided are a developing device and an image forming apparatus which employ a hybrid development method, have a toner-collecting developer supporting member and keep toner collecting ability stable for a long period of time to form high-quality images without development hysteresis (ghost) over a long period of time. A toner separation member abutting the toner-collecting developer supporting member through a toner-collecting developer layer is provided, and the toner separation member is applied with a bias voltage to form an electric field in such a direction as to pull toner away from the toner-collecting developer supporting member to prevent the toner from accumulating on the surface of the toner-collecting developer supporting member.

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Uji, Japan

Makiko Watanabe