Hitachi, Ltd.

Kyocera Corporation

Masafumi Suzaki

Katsumasa Mikami

Akira Sasaki

Tomoji Kitagishi

Yousuke Nagano

Shigetaka Furukawa

Fumio Takahagi

Akiyoshi Hakoyama

Ryooichi Kobayashi

Yoshihito Takahashi

Yasuo Nishiguchi

Tsuyoshi Yasutomi

Ryoichi Shiraishi

Takeo Honma

Masahiko Saito

Ryoichi Kobayashi

Masaru Nakano

Tetsuro Akasaki

Yoshifumi Homma

Kunio Tajima

Yoosuke Nagano

Kenichi Ebata

Rooichi Kobayashi

Tsugio Kikuchi

Registration controlling methods are provided for a color electrophotographic apparatus capable of forming an image without color registration errors and uneven color. This is accomplished by preventing a photosensitive medium from being undesirably moved in the direction perpendicular to the transportation direction caused by an electrostatic attractive force between the photosensitive medium and an intermediate transfer device, even if there is a twist between the fixed axis of the member supporting the photosensitive medium and the axis of the member supporting the intermediate transfer device. With these methods, a fur brush cleaner made of a conductive brush is detached from the intermediate transfer device during the time period after the start of driving the photosensitive medium and until the front edge of the photosensitive medium reaches the intermediate transfer device. A small amount of toner therefore always exists between the intermediate transfer device and the photosensitive medium during the transportation of the photosensitive medium, thereby reducing the electrostatic attractive force between the intermediate transfer device and the photosensitive medium and preventing the photosensitive medium from being undesirably moved in the direction perpendicular to the transportation direction. Also during this time period, the photosensitive medium is irradiated by a fade lamp to reduce electric charges on the photosensitive medium.

Electrophotographic apparatus having an intermediate transfer device and

Guide rollers are provided to be symmetric with respect to a center of the thermal head. The guide rollers comprise first two guide rollers provided in a vicinity of the thermal head, a guide roller provided in a vicinity of the supply core, a guide roller provided in a vicinity of the take-up core, and second two guide rollers. The second two guide rollers are disposed nearly in a vicinity of the first two guide rollers. The back tension force adding members comprise a fixed brake adding member provided at the supply shaft and an outer peripheral brake adding member for contacting the ink ribbon. The ink ribbon shifting down phenomenon can be prevented. The dirty background and the rubbing transfer phenomenon can be reduced. The aligned winding of the ink ribbon make possible a practical reciprocating ink ribbon cassette. without concern about ink ribbon winding accidents.

Ink ribbon cassette for use in a thermal transfer printer and having

An electrophotography printer includes a drum formed of a non-magnetic cylindrical body having an outer circumferential surface to which a photosensitive material is applied, end brackets attached to opposite ends of the drum, and a drum shaft for transmitting a driving torque to the drum. A connection structure between the drum and the drum shaft includes end bracket shafts provided on the end brackets, a hole formed in the drum shaft so as to be capable of engaging with one of the end bracket shafts, parallel pins provided on the end bracket shafts so as to be perpendicular to the axes thereof, and at least one taper groove formed in an end portion of the drum shaft. When the drum is housed, one of the parallel pins and the taper groove engage with each other while the whole of the drum is pressed toward the drum shaft by an elastic member, thereby reducing the non-uniformity of the rotation of the drum.

Drum driving unit of electrophotography printer

A combination of a thermal printer and an invertible ribbon cassette has a mechanism for preventing a portion of the inked ribbon extending between a supply core and a take-up core of the ribbon cassette from shifting in the direction perpendicular to the longitudinal direction of the inked ribbon with respect to a printing head. The mechanism includes a substantially planar surface of a platen, and a printing head is urged against the planar surface of the platen through the inked ribbon portion and a sheet to which solid ink in the area on the inked ribbon portion is transferred by the printing head. The width of that area on the inked ribbon portion in the widthwise direction of the inked ribbon is at most equal to a half of the width of the inked ribbon. Alternatively, the mechanism includes a detector mechanism operative in response to the variation in diameter of the inked ribbon wound on the supply core for applying a variable back tension in the reverse direction to the tension acting on the inked ribbon portion by the take-up core.

Thermal printer and invertible ribbon cassette therefor including a

The face pressure distribution shape of the graze portion of the thermal head is made to be consistent with the temperature distribution shape of the graze portion of the thermal head. The temperature distribution shape of the graze portion of the thermal head is made to be consistent with the face pressure distribution shape of the graze portion of the thermal head. The graze portion of the thermal head is formed projectingly in two steps, and the heating resistor element of the thermal head is provided on the top portion of the graze portion of the thermal head. A thermal transfer printer having no ink void and no ink transfer unevenness can be obtained.

Thermal transfer printer having an improved thermal head to improve ink

In a thermal printer having a flat platen, a flat platen support mechanism comprises a flat platen support plate, and a frame body. A projection having a curvature is provided between the flat platen support plate and the frame body. The projection having a curvature is to be swingable freely and to be movable with a slip movement. The projection is arranged on a center line of a flat platen width. When a thermal head is pressed with the flat platen, the flat platen swings smoothly. The thermal head is face contacted uniformly with the flat platen.

Thermal printer having a flat platen support mechanism

A thin film type thermal head includes a head substrate member, a partial projected glaze portion mounted on the head substrate member, a plurality of heating resistor elements provided on the partial projected glaze portion with each of the heating resistor elements having a uniform thin thickness and two electrode end portions. A common electrode is provided on the partial projected glaze portion and an individual control electrode is also provided on the partial projected glaze portion. The partial projected glaze portion has at least two projected portions of different height with the plurality of heating resistor elements having a portion thereof disposed on at least the highest projected portion of the partial projected glaze portion with both electrode end portions of each of the heating resistor elements being disposed on the partial projected glaze portion other than the highest projected portion of the partial projected glaze portion so as to enable a recording dot to become narrow in the printing direction.

Thermal head

A thermal head is pressed against a platen consisting of rubber through a recording paper or a heat sensitive paper. The thermal head is provided a head base, a glaze layer portion mounted on the head base, and a heating resistor portion provided on the glaze layer portion. An unit area surface pressure applied from the glaze layer portion of the thermal head to the recording paper or the heat sensitive paper is set to not less than 0.3 kg/mm.sup.2. A hardness of the rubber of the platen is adapted to about Hs 40.degree.-Hs 100.degree.. The high areas of the surface of the recording paper or the heat sensitive paper are flattened to increase the smoothness of the surface of the recording paper or the heat sensitive paper. A high quality printed product of the thermal transfer printer or the thermal printer can be obtained even when the relatively rough recording paper or the heat sensitive paper is used as the object paper.

Printer having a thermal head

A thermal transfer printer wherein the carriage is equipped with the ribbon cassette and the thermal head and has a take-up shaft engageable with the take-up core of the ribbon cassette, and clutch means is provided between the motion converting means and the take-up shaft of the carriage, rotational force is transmitted from said motion converting means to the clutch means, and the clutch means cuts off the transmission of the rotational force to the take-up shaft. The rubbing transfer phenomenon does not occur, since, the ink ribbon starts to travel before the thermal head contacts the platen or after the thermal head separates the platen. It is possible to effect control such that no rubbing transfer occurs even when the thermal head is pressed against the platen to effect printing while the carriage is moving transversely at high speed.

Thermal transfer printer

A thermal trasfer printer including a thermal head, and a platen positioned against the thermal head through a printing sheet. The thermal head has a substrate formed of heat insulating material, at least one glaze layer on a top surface of the substrate extending longitudinally thereof, a plurality of heat generating elements on the glaze layer, a plurality of electrodes each connected to the heat generating elements in a manner to form an opening for the heat generating elements and a protective layer for preventing the electrodes and heat generating elements from contacting the printing sheet to avoid their wear. A portion of the protective layer for protectng the heat generating elements has a height which is greater by more than 5 .mu.m than the height of a portion of the protective layer for protecting the electrodes. The width of the glaze layer transversely of the substrate is less than 200 .mu.m at a location which is 10 .mu.m below a top surface of the portion of the protective layer for protecting the heat generating elements in a vertical direction. The platen is a flat platen and its deflection caused to occur by a biasing force exerted on the thermal is more than 0.02 time and less than twice as great as the height of the glaze layer.

Thermal print head

In the thermal transfer printer for printing with an ink ribbon in plural columns, a center of a flat portion formed on the platen roller of a contact portion of the thermal head and a center of the thermal head are shifted corresponding to an amount of shift of printing position as against a center of width of the ink ribbon. When the printing position is set above as against the center of width of the ink ribbon, the center of the thermal head is set above width (P) of the flat portion being formed on the platen roller of the contact portion of the thermal head. When the printing position is set below as against the center of width of the ink ribbon, the center of the thermal head is set below width of the flat portion being formed on the platen roller of the contact portion of the thermal head. The present invention can prevent the shifting-up or the shifting-down of the ink ribbon at the thermal head in structure in which the center of the ink ribbon width and the center of the printing shift in the plural columns printing.

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Hitachi, Japan

Masafumi Suzaki