Hitachi, Ltd.

Hitachi Koki Co., Ltd.

Yuzuru Simazaki

Takao Kumasaka

Takao Umeda

Tatsuo Igawa

Yasuro Hori

Youji Hirose

Tetsuya Nagata

Isamu Komatsu

Takao Miyashita

Kunio Satoh

Noboru Tokuyasu

Susumu Tateyama

Nobuyoshi Hoshi

Yasuo Takuma

Fumio Nakano

Seikichi Tanno

Hisao Okada

Kiyohiko Tanno

Tomio Sugaya

Ken Sasaki

Akira Terakado

Shigetaka Fujiwara

Motoo Yamaguchi

Masato Yamada

Ryota Doi

Yuji Kumagai

Ikou Fukazawa

An image formation method for forming an image of a plurality of colors through a charging step, an image exposing step, a developing step and a transferring step, wherein the image exposing step is made up of a first image exposing step and a second image exposing step, the developing step of at least one color is carried out after the first image exposing step, and in the subsequent second image exposing step, the toner image area formed by the developing step is exposed and charge latent images for forming toner images of the rest of the colors are formed while a potential of the toner image area is selectively shifted.

Image formation method and image formation apparatus

In a developing apparatus in which a developer containing magnetic particles is carried on a developer carrier to form a magnetic brush and a latent image on a latent image carrier opposing the developer carrier is developed by the magnetic brush, the magnetic brush bristle height and the developing gap are controlled to keep density of a first color image and density of a second and the ensuing color images in color development at predetermined values or more, thereby maintaining quality of printed images stably. There are also provided method and apparatus of measuring the bristle height of the magnetic brush of the developing apparatus, which bristle height is a parameter indispensable for control of the above developing condition, under the dynamic condition that the developing roller rotates.

Magnetic brush with bristle height equal to developing gap

An image recording apparatus including a photosensitive medium. A voltage is applied between the photosensitive medium and a developing sleeve of a developing unit, and a current flowing between the photosensitive medium and the developing sleeve is measured to be converted into a pulse waveform which is then compared by a predetermined reference value. On the basis of the result of the comparison, a gap is determined between the photosensitive medium and the developing unit, which is then advanced or retracted toward or from the photosensitive medium in accordance with the determined gap. Owing to the recording method carried out by the image recording apparatus, the gap can be selectively determined by observing the current waveform pattern of the current flowing between the photosensitive medium and the developing sleeve while decreasing gradually the gap therebetween, whereby a relation between the gap and height of a magnetic brush can definitely be established. Since the gap can be set within a range from a value representing an initial contact state in which the magnetic brush starts to contact with the photosensitive medium to a value representing a wholly contact state in which the whole magnetic brush contacts with the photosensitive medium with the aid of a current curve of the current flowing between the photosensitive medium and the developing sleeve, a contacting force of the magnetic brush bearing on the photosensitive medium can be weakened.

Image recording method including determining a gap between a

An electrophotographic recording apparatus is provided having a reduced overall size. The space around a photosensitive member required for the developing unit to be located is minimized, more particularly, it i minimized in the lengthwise directional space. In the electrophotographic recording apparatus having a photosensitive member which moves at a predetermined speed; an exposure device for exposing the photosensitive member; a developing unit for developing an electrostatic latent image obtained by the exposure; and a transferring device for transferring a developed visible image to a recording paper sheet or the like, the developing unit is composed of developing devices, a plurality of supporting members for supporting the developing devices and an element for rotating the supporting members. The supporting members can be rotated while making a portion adjacent to a widthwise directional end of the photosensitive member to be a supporting point in a range from a state where the surface of the photosensitive member and the surface of a developing roll of each developing device run parallel to each other to a state where they are positioned substantially perpendicular to each other.

Electrophotographic recording apparatus having a plurality of developing

A transfer apparatus for electrophotography is disclosed in which the resistance values of a transfer belt and the recording paper are measured, and the current value applied to a device for charging a member is set on the basis of the electrical resistance values. The charging device of the transfer belt is adapted to be taken up and reeled out and to circulate along a track. This configuration assures a stable transfer characteristic against the secular environmental variations of the component elements, lengthens the intervals of replacement of the charged member, and hence increases the mechanical life of the transfer apparatus and the electrophotographic apparatus using the same.

Corona deterioration and moisture compensation for transfer unit in an

In a multi-color LBP (laser beam printer) or a full-color LBP, two image producing elements each composed of charge-exposure-develop devices are arranged around one drum, and each of the image producing elements includes a developer capable of color changing for achieving a color change developing in every one revolution. In this way, it is made possible to practice a multicolor printing or a full-color printing in two rotations of one photosensitive drum. This printer has a higher printing speed and a smaller size of the apparatus in comparison with that of a one drum four rotation system and that of a one drum one rotation system, respectively. Further, the system includes several features common to two-color LBP printing art, making it possible to conveniently utilize the latter printing art.

Multi-color electrophotograph apparatus

An electrophotographic image transfer member of bias-roller transfer type is capable of pressing a recording medium into contact with a toner image. The image transfer member has a rotatable supporting member, an elastic member provided around the supporting member, and a conductive resin layer formed on the surface of the elastic member. An electrical path is formed to enable supply of a bias voltage to the conductive resin layer. An image transfer device has the image transfer member and a cleaner capable of removing toner from the image transfer member upon frictional contact therewith. An electrophotographic apparatus has an image transfer member for bringing the recording medium into pressure contact with the toner image and for applying the bias voltage, and a mechanism for bringing the image transfer member towards and away from the photosensitive member in response to a signal indicative of execution of one of several basic steps of the electrophotographic process.

Electrophotographic image transfer member, electrophotographic image

An electrophotographic recording apparatus comprises an electrostatic charging device for electrostatically charging a surface of a photosensitive body, an exposure device adapted to form an electric charge latent image on the surface of the photosensitive body, a developing device for effecting developing of the electric charge latent image by using a developer containing at least a toner to thereby form a toner image, and a transferring/fixing device for transferring and fixing onto a recording sheet of paper the toner image formed on the surface of the photosensitive body, the exposure means including a laser exposure section for exposing the surface of the photosensitive body to an optical image of high resolution and a light emitting diode array exposure section for exposing the surface of the photosensitive body to an optical image of low resolution.

Electrophotographic recording apparatus

A developing device is of non-contact development type in which a toner is jumped to a photoconductor to develop a latent image on the photoconductor. The developing device is controlled in height of a developer-agent layer on a developer roll, and sets a developing gap between the photoconductor and the developer roll in such a manner that a driving electric field required for jumping of the toner can be maintained at the air gap between the photoconductor and a developer-agent layer on the developer roll and developing bias voltage can be brought to a value lower than charged electric potential of the photo-conductor. By setting the developing bias voltage to the valve lower than the charged electric potential of the photoconductor, jumping of additional or unnecessary toner is restricted so that contamination of an image and a recording sheet can be prevented. Further, a multi-color recording apparatus having this developing device prevents toner developer agents different in color from being brought into contact with each other to form a clear multi-color image without mixing in color and contamination.

Developing device and multi-color recording apparatus

The invention relates to a liquid crystal optical switch array in which optical switch elements are opened and closed by the time-sharing drive and to an optical printer using this optical switch array. The optical switch element comprises a ferroelectric liquid crystal having a relaxative memory effect, signal electrodes and scanning electrodes which sandwich the liquid crystal layer, and a resistor element which is formed between the scanning electrode and the liquid crystal. A line selection signal is sequentially supplied to the scanning electrodes, these scanning electrodes become substantially the open state when the selection signal is not supplied. When the scanning electrodes are open, the resistor element has a predetermined resistance value. When the selection signal is supplied to the scanning electrodes, the resistor element has a lower resistance value.

Time-sharing drive liquid crystal optical switch array and optical

A multiplexed driving method of an optical switching element employing ferroelectric liquid crystal with a negative dielectric anisotropy including signal electrodes and common signal electrodes arranged in matrix and a ferroelectric liquid crystal layer disposed therebetween so as to constitute pixels at the respective facing portions of the signal electrodes and the common signal electrodes comprising a step of applying a common writing signal voltage to one of the common signal electrode to select pixels to which information be written, simultaneously applying a common status holding AC signal voltage to the other common signal electrodes covering non-selected pixels and simultaneously applying one of two signal pulses with opposite polarities to the signal electrodes, whereby resultant information writing voltages formed in combination of the common writing signal voltage and the signal pulses, which are enough to determine the orientation of the ferroelectric liquid crystal molecules, are applied on the selected pixels and resultant AC status holding voltage formed in combination of the common status holding AC signal voltage and the signal pulses which determine the limited bias voltage for the resultant AC voltage are applied on the non-selected pixels.

Multiplexed driving method for an optical switching element employing

A liquid crystal display device is disclosed in which a liquid crystal material mixed with a dichroic dye is held between a pair of substrates whose facing surfaces are provided with electrodes, so that a picture element is made up of a pair of facing portions of the electrodes and a portion of the liquid crystal material sandwiched by the facing portions, in which a reflecting plate is adjacent to one of the substrates, and in which at least one of the substrates is formed of a birefringent material having slow and fast principal axes of birefringence. In the above device, an angle between the direction of the absorption axis of the dichroic dye and one of the principal axes of birefringence of the substrate is selected so that the contrast and viewing-direction characteristic of the device can be improved.

Liquid crystal display device

This invention relates to a liquid crystal display element comprising a pair of transparent substrates, electrodes formed on the individual surfaces thereof facing each other, a liquid crystal material layer held between the substrates, and gap controlling material for keeping the gap between the substrates, and is characterized in that the gap controlling material is dispersed and fixed on the substrate surface by an insulating coating film such as an orientation controlling film. When the gap controlling material is thus dispersed and fixed, it does not move between the substrates, and hence the change of the gap length between the substrates is prevented, so that there can be obtained a liquid crystal display element in which the distance between the substrates is uniform. Moreover, when the insulating coating film is an orientation controlling film, the dispersion and fixation of the gap controlling material is completed simultaneously with the formation of the orientation controlling film, so that beneficial effect can be obtained also with respect to working efficiency. When the gap controlling material is a combination of a polymer solid and an insulating material having a higher softening point and regidity than those of the polymer solid, the uniformalization and change prevention of the gap length are more effectively achieved.

Liquid crystal display element with gap controlling material and process

A stator structure for the induction motor is disclosed, in which the winding accommodated in the slots of the stator iron core has one end portion, outside of the stator iron core, shaped to provide a flared bell-like opening, and the other end portion thereof, outside of the stator iron core, forming short-passed winding and being provided with an opening sufficiently large to permit insertion of the shaft of the rotor. Between the inner surface of the short-passed end portion and a given portion of the surface of the stator iron core a coil-supporting member is disposed. The outer surface of the coil-supporting member has a shape along the inner surface of the other coil end portion, while the inside thereof is so shaped as to provide a sufficient space or air gap with respect to the rotor to be inserted. The coil-supporting member is made of an elastic material and adapted to be forcibly fitted between the inner surface of the short-passed coil end portion and the given portion of the surface of the stator iron core from the opening of the bell-shaped coil end portion through the rotor-accommodating cavity formed in the stator core, thus closely contacting the inner surface of the short-passed end portion. Means is provided for bringing at least part of the coil-supporting member into close contact with the short-passed coil end portion and rendering them immovable with respect to each other.

Growing community of inventors

Hitachi, Japan

Yuzuru Simazaki