Sharp Kabushiki Kaisha Corporation

Shirou Wakahara

Kazuya Masuda

Yukihito Nishio

Hirokazu Fujita

Nobuhiko Nakano

Kenji Tani

Katsumi Adachi

Fumio Shimazu

Eiichi Kido

Hironori Ogasawara

Tomohiro Oikawa

Hideo Yamasa

Yukikazu Kamei

Hiromu Yoshimoto

Iwakazu Honda

Hiroshi Doshoda

Koichi Inui

Yasuichi Onose

Hajime Yoshinaga

Yuuhi Yui

Yasuhiro Takai

Yoichi Yamamoto

Tomohiko Okada

Yoshitaka Matsumoto

Hideki Ohnishi

Daisaku Imaizumi

Tomoko Nishino

Koji Tsukamoto

Hideki Onishi

The present invention relates to an image forming apparatus with a charging member which charges an image bearer with a photoconductive surface. Forming a layer containing ferroelectric as part on the charging member, and applying the electric field formed by dipoles of the ferroelectric, the photosensitive member surface is electrified, thereby downsizing a charger and reducing power consumption thereof are achieved for realizing low-cost and reducing the number of consumable parts sufficiently.

Image forming apparatus

An image forming apparatus capable of forming an image with a uniform density includes a toner carrier, an opposing electrode, a high voltage power source for supplying a voltage to generate potential difference between the toner carrier and the opposing electrode, a control electrode arranged between the toner carrier and the opposing electrode and having a plurality of electrodes, and a control power source unit for implementing a plurality of potential states to each of the electrodes of the control electrode. The control electrode includes an insulating substrate, the plurality of electrodes provided on the insulating substrate and having passage portions for the toner, and a dielectric layer formed on a side facing the opposing electrode such that attracting force Fc attracting the toner adhered on the surface of the control electrode facing the opposing electrode is made smaller than attracting force Fb attracting the toner adhered on the opposing electrode. The control power supply unit includes an image forming unit for forming an image on a surface of a recording medium conveyed on the opposing electrode by applying prescribed potentials to respective ones of the plurality of electrodes and an electric field applying unit for applying an electric field of which electric field direction changes between the opposing electrode and the control electrode and which ensures that an electric force FE received by the toner adhered on the control electrode is greater than the attracting force Fc and that the force FE is smaller than the attracting force Fb.

Image forming apparatus in which toner is removed by changing electric field between opposing electrode and control electrode

An image forming apparatus of the present invention includes ring electrodes for controlling flying of toner from a carrier to a sheet, and a control power source section for applying a potential that is in accordance with an image signal to each ring electrode. The control power source section carries out, in the case where the image signal is applied to each ring electrode so that the potential is applied at the same timing, a control of shifting the timing of applying ON potential so that the sum of transient current flowing through each ring electrode at a predetermined time is smaller than the sum of maximum value of the transient current flowing through each ring electrode. This ensures that the amount of transient current supplied at a predetermined time to each ring electrode by the control power source section is reduced.

A transfer apparatus having a photoconductor drum for holding thereon an image formed by toner charged with a negative polarity and a transfer roller disposed opposite the photoconductor drum, in which paper is fed to an area where the photoconductor drum and the transfer roller face each other and the toner image on the photoconductor drum is transferred to the paper by using a unidirectional transfer electric field formed by the transfer roller. The transfer roller also serves as charge supply control device for supplying a charge to the toner held on the photoconductor drum to thereby substantially neutralize the charge of the toner while retaining the negative polarity of the toner.

Transfer apparatus

An image forming apparatus capable of forming an image with uniform density includes a toner carrier for carrying a toner, an opposing electrode arranged opposing to the toner carrier, a high voltage power supply unit for supplying a voltage to generate a potential difference between the toner carrier and the opposing electrode, a control electrode including a plurality of electrodes arranged between the toner carrier and the opposing electrode, and a control power supply unit for implementing a plurality of potential states at respective ones of the electrodes of the control electrode, controlling passage of the toner through a passage portion, and for forming an image on a surface of a recording medium conveyed over the opposing electrode. The control electrode includes an insulating substrate, the aforementioned plurality of electrodes having a passage portion through which the toner passes provided in the insulating substrate, and a plurality of float electrodes having an opening provided such that at least part of the plurality of electrodes are directly or electrically exposed to the toner carrier, for making uniform an electric field formed between the toner carrier and the opposing electrode.

Image forming apparatus having float electrode provided to make uniform electric field

A recording medium includes a liquid crystal material whose polarizing axis is controlled by an applied electric field, a layer including the liquid crystal material, and spacers for maintaining a constant spacing between the layer, and is formed in the form of a sheet. A visible image is recorded on the recording medium by applying a predetermined electrostatic charge image composed of electrostatic charges on a surface thereof and by controlling the polarizing axis of the liquid crystal material by an electric field formed by the charges of the electrostatic charge image, which controls reflectance or transmittance of incident light.

Recording medium and image forming apparatus for forming image thereon

An image forming unit includes: a toner support for supporting the toner; an opposing electrode opposed to the toner support; a high-voltage power source for supplying a high voltage to produce a potential difference between the toner support and the opposing electrode; a control electrode having an insulative substrate disposed between the developer support and the opposing electrode, a plurality of gates formed in the insulative substrate for forming the passage of the developer, and electrode groups provided around a multiple number of the gates; and a control device for selectively applying multiple potential states to each electrode in the control electrode, wherein the control device controls the passage of the developer through the gates by applying the predetermined voltage to electrode groups so as to form an image on the surface of the paper which is being conveyed over the opposing electrode. In this configuration, a slanted portion for reducing the component of a force, acting on the toner residing on the paper, in the direction opposite to the conveyed direction of the paper, is provided on the downstream side of the opposing electrode.

Image forming apparatus using gates and electrodes for selectively passing toner

In an image forming unit having a toner supplying section and a printing section, the toner supported on the toner support is caused to jump through gates so as to pass through the gates and adhere to the paper which is being conveyed from a paper cassette, whereby an image is formed directly on the paper. In this configuration, the jumping of toner from the toner support is controlled based on the application time of the voltage applied to the control electrode, and/or other factors.

An image forming apparatus is described that records with the developer a desired image on a recording medium, which is transported in a transporting direction through a gap between a control electrode and a counter electrode, by supplying a potential to the control electrode based on image data and selectively permitting the developer to pass through gates. The control electrode is a flat-shaped member interposed between the developer carrier and the counter electrode. It has a pair of support regions that are spaced apart from a central region, one supporting region on each side of said central region in the transporting direction. A first support member has a first flat surface and a first fixing member that holds one support region of the control electrode member fixedly on said first flat surface and (2) a second support member has a second flat surface and a second fixing member that holds the other support region of the control electrode member fixedly on said second flat surface. An adjustment feature can be used for slightly deforming the supporting member in the transporting direction.

Image forming apparatus having a control electrode support structure for fine adjustment of the control electrode in a region of the gates

A region with high resistance equal to the atmosphere is provided in a transfer roller. A discharge electrode capable of performing discharge between a base member and the discharge electrode is arranged within the region. When a predetermined electric potential is applied to the discharge electrode from a transfer power supply, the electric potential is separated and respectively applied to a first region in the transfer roller and a second region between the transfer roller and a photosensitive drum. At this time, since both the first and second regions are regions of high resistance, the electric potential applied to each region is equal, and therefore the electric field can never be concentrated in the second region. Moreover, since a predetermined electric field is formed in the first region, even when the transfer roller and photosensitive drum come into contact with each other, a transfer current can never collect in the contact. Thus, when a high electric potential is applied to the transfer roller, it is possible to avoid toner from unpreparedly flying from the photosensitive drum to paper, and prevent concentration of the transfer current in a region between the transfer roller and photosensitive drum, where the paper is not present.

Charge supply device for charging bodies in image forming apparatus and the like

The opposing electrode has an opposing portion facing the peripheral surface of the toner support and a brush portion formed of a partial circumferential surface continuous to both ends of the opposing portion. The opposing electrode is rotated about a rotary axis disposed at the center of the partial circumference forming the brush portion. When the opposing electrode rotates, the brush portion comes into contact with the undersurface of the control electrode. The opposing electrode is applied with a high voltage, e.g. 2 kV from a high-voltage power source so that the brush portion can remove the toner adhering to the control electrode.

Control electrode cleaning device

Formed between an opposing electrode and a toner support by a high voltage applied from a high-voltage power source is an electric field required for the toner carried on the toner support to jump toward the opposing electrode. A shield power source is provided to apply an identical voltage as the surface potential of the toner layer carried on the toner support.

Image forming apparatus that forms image on a medium by jumping developer

Formed between an opposing electrode and a toner support by a high voltage applied from a high-voltage power source is an electric field required for the toner carried on the toner support to jump toward the opposing electrode. The high-voltage power source and the duration of voltage application are adjusted so as to pick out suitable developer particles to be used for forming images.

Image forming apparatus using jumping toner/developer

An object of the present invention is to provide an image forming apparatus for forming images which are always and stably high quality regardless of changes of ambient conditions. In the image forming apparatus, a counter electrode is disposed facing a toner holder for holding at least one color toner, to generate a potential difference between the toner holder and the counter electrode by use of various types of power supplies. Between the toner holder and the counter electrode, a counter electrode is interposed, which is provided with a plurality of gates disposed on an insulating substrate and electrode groups respectively disposed around the plurality of gates. According to the potential difference between the toner holder and the counter electrode, it is controlled whether or not the toner is caused to pass through the gates. In the image forming apparatus, a resistance value of a cleaning member is detected for removing the toner stuck on the control electrode. On the basis of the detected resistance value, ambient conditions are determined. On the basis of the conditions, a state of at least one of elements in the image forming apparatus is controlled.

An object of the present invention is to provide an image forming apparatus for enabling toner to easily pass through gates of control electrode and increasing the scattering efficiency of the toner to improve the printing quality. Since a sticking force between the toner and toner holder or among particles thereof is weakened and the toner is held on the toner holder with a slight binding force between the toner holder and the control electrode, a voltage applied for enabling the toner to pass through the gates of the control electrode and scatter toward the counter electrode can be minimized as long as the toner can pass through the gates of the control electrode. In other words, a pulse is applied to a shielded electrode just before the toner held on the toner holder passes through the gates of the control electrode, so that the sticking force between the toner and the toner holder or among particles thereof can be weakened, or the toner can be transformed into cloud-like particles. Accordingly, the toner can easily pass through the gates of the control electrode and the scattering efficiency of the toner is increased to improve the printing quality.

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Chiba, Japan

Shirou Wakahara