Hitachi Koki Co., Ltd.

Toshio Hiki

Yoshikane Matsumoto

Takashi Nakamura

Masao Miyasaka

Shingo Nakahara

Hiroyuki Kurosawa

Kohichi Yageta

Kazunari Kodama

Shinichi Sakamoto

Toshitaka Ogawa

Makoto Kurosawa

Shigenori Suematsu

Tsuneki Kobayashi

Hiroto Inagawa

Hirotaka Kobayashi

Kazuo Sugano

Nobuhiko Itoh

Shinichi Watahiki

Toshiaki Fujieda

Hiroshi Nishimura

Shozo Ishii

Youichi Hujita

Koichi Yageta

Akira Igarashi

Kiyoo Kawate

Kohki Kushima

Koichi Saga

A thickness of a form document loaded in a pin feed tractor is measured to appropriately adjust a gap between a platen and a print head. A projection formed on a pressing block is linearly moved toward and away from the form document supported on a tractor cover. The pressing block is moved by a stepping motor, and an amount of rotations of the stepping motor is detected to measure the movement of the projection. A first amount of rotations is detected under a condition where the form document is not loaded and subsequently a second amount of rotations is detected under a condition where the form document is loaded. The thickness of the form document is computed based on a difference between the first amount of rotations and the second amount of rotations to eliminate influence of resilient deformation of the tractor cover.

Device for measuring thickness of a form document in an impact printer

A recording sheet is positioned at one of a plurality of starting positions based on a printing mode used in previous printing operations. When printing operations are started in a printing mode different from the previous printing mode, the recording sheet is transported either in a forward direction or in a reverse direction to a corresponding starting position. Then, actual printing is started. On the other hand, when printing operations are started in the same printing mode, actual printing is started immediately. In this way, printing speed is improved.

Recording device including buffer mechanism for transporting recording medium in forward and reverse directions

A linear shuttle motor assembly used for reciprocally moving a printer head includes a rotor and a stator having the same mass. A loud, i.e., the printer head, is connected to the stator and a counter balance to the rotor. The rotor and the stator are driven to reciprocally move in mutually opposite directions. A 180 degree phase synchronizing mechanism is used to synchronize phases of the rotor and the stator. The mechanism is fixed to a housing and connected to the rotor and the stator. By this configuration, the amount of power transmission loss is reduced to a minimum, which improves energy conversion efficiency.

Linear shuttle motor assembly and a controller therefor

A printer and ribbon cassette with gears for transmitting power from the drive motor of the printer to the ribbon cassette. Guides are provided for guiding the ribbon cassette in a direction perpendicular to the rotational axis of the gears, so that the ribbon cassette slides easily into place and the gears engage easily, but the gears are tightly engaged.

Impact printer and ribbon cassette

A dot line printer has a plurality of print hammers accommodated in a hammer bank, which make dot impressions on a sheet of print paper as the hammer bank reciprocally moves in a print line direction perpendicular to the direction in which the sheet of print paper is fed. To print L dot lines at a time with each of forward and backward movements of the hammer bank, the print hammers are divided into a preselected number of groups so that each group includes N number of print hammers where L and N are integers equal to or greater than 3. The print hammers in each group are displaced one dot line distance from one another in the sheet feeding direction. The print hammers in each group are further displaced in the print line direction by respective predetermined distances from their home positions so that the respective hammers in each group do not impinge upon the sheet of print paper simultaneously. The print hammers equal in number to the least common multiple of L and N or integer multiples of the least common multiple thereof are integrally formed into a module structure to facilitate the manufacture and management of the hammer assemblies.

Print hammer arrangement in dot line printer minimizing number of

In a dot-line printer, a hammer bank carrying a plurality of dot printing hammers reciprocally moved along a printingline. Each of the printing hammers is made up of a leaf spring, one end of which is fixedly secured to the hammer bank and to another end of which a printing pin is attached. According to the invention, the plurality of dot printing hammers are separated into an odd-number group and an even-number group, in which the printing hammers in each of the odd-number and even-number groups are further separated into a predetermined number of sub-groups. The printing hammers in the odd-number group are arranged in the upper side of the printing line so that the printing pins extend downwardly and the printing hammers in the even-number group are arranged in the lower side of the printing line so that the printing pins extend upwardly. The printing pins in each of the sub groups of the odd-number group are positioned along a straight line inclined by a predetermined angle with respect to the printing line and the printing pins of the printing hammers in each of the sub groups of the even-number group are positioned along another straight line parallel to the aforementioned straight line. In order to facilitate fabrication of the printing hammers, the printing hammers in each of the sub groups are formed integrally to be in a comb-like shape.

Printing head in a dot-line printer

A printing hammer assembly is provided having a plurality of hammer springs arrayed side by side at a predetermined pitch in a shuttling direction of a hammer bank. A front yoke is provided in front of the hammer springs, and a plurality of rectangular grooves are formed at an upper portion of the front yoke so as to receive therein corresponding rectangular plungers provided at the hammer springs. A gap is defined between a side wall of the groove and a side wall of the plunger. The gap is sufficiently large for tolerating inaccurate assembly of the hammer springs and the front yokes. Further, a subordinate front yoke is provided on the front yoke at a position of an array of the grooves.

Dot line printer having improved yoke assembly

A dot line printer with a paper feed time controlling capability includes a hammer bank accommodating a plurality of print hammers, a shuttle mechanism for shuttling the hammer bank back and forth along a print line, and a sheet feeding mechanism for feeding a sheet of paper in a direction perpendicular to the direction in which the hammer bank shuttles. When a first predetermined amount of a line space feeding is to be carried out after completion of one line printing, a hammer bank reversing time is prolonged. When more than the first predetermined amount of the line space feeding but less than a second predetermined amount of line space feeding is to be carried out, it is carried out during an extended period of time including both the hammer bank reversing time and the subsequent hammer bank scanning time without prolonging the hammer bank reversing time. Further, when the amount of the interline space feed is more than the second predetermined amount, it is taken place during a prolonged hammer bank reversing time and also the subsequent hammer bank scanning time.

Dot line printer with paper feed time controlling capability

A dot line printer having ink ribbon guides for stabilizing running performance of an ink ribbon. A dot line printer includes a hammer bank, a shuttle mechanism, a platen and ink ribbon guides. The hammer bank has print hammers for forming a plurality of dot impressions. The shuttle mechanism has one side positioned adjacent to one end of the hammer bank for reciprocally moving the hammer bank. The platen is adapted for bearing dot impression force, and a part of the ink ribbon is positioned at an ink ribbon path extending along the platen. The ribbon guides have a first guide positioned adjacent to another end of the hammer bank, and a second guide positioned adjacent to another side of the shuttle mechanism. The ink ribbon guides guide travel of the ink ribbon at the ink ribbon path. The ribbon guides further include a third ink ribbon guide positioned between the hammer bank and the shuttle mechanism for further guiding travel of the ink ribbon at the ink ribbon path.

Dot line printer having ink ribbon guides

A shuttle printer carries out printing on a printing paper when a hammer bank shuttles back and fourth. At the beginning of the hammer bank reversal at the right or left end in the hammer bank shuttling path, a braking force is exerted to a shuttle motor which drives the hammer bank and an acceleration force is exerted to the shuttle motor immediately after the hammer bank turns around. In order to set a reversing duration of the hammer bank at constant, the braking force and the acceleration force exerting durations are prolonged from a predetermined minimum to a value when the hammer bank reversing duration is shortened to an extent as desired, whereby a printing paper can be fed a predetermined amount within the hammer bank reversing duration as desired.

Apparatus for controlling reversing duration of hammer bank in shuttle

A paper tension adjusting device in which one of the tractors with feeding pins changing feeding apertures in the paper is movable widthwise to adjust widthwise paper tension. The desired tension is determined from paper thickness which is in turn determined from the hammer flight time. Lengthwise tension is adjusted by adjusting paper clampers separated from the tractors. The tension is both widthwise and lengthwise directions is determined by optically sensing the positions of the feeding pin with respect to the aperture in which that pin is engaged.

Paper tension adjusting device and method for a printer

A dot-line printer has a hammer bank carrying a plurality of printing hammers arranged in groups, each group having a predetermined number of printing hammers displaced from one another by predetermined numbers of dot-lines in the direction of paper feed. A shuttle mechanism causes the hammer bank to undergo reciprocating shuttle movements with a reversing period between successive shuttle movements. A character line, covering a predetermined number of dot-lines, is printed over a plurality of shuttle movements, a paper feed mechanism causing the paper to move a predetermined number of dot-lines in the reversing period between shuttle movements. A number of blank dot-lines separate a printed character line from the beginning of the first dot-line of the next character line to be printed. A control mechanism sets the reversing period between successive shuttle movements to be longer than the paper feed time to move the paper to the first dot-line to be printed after the preceding character line has been printed and causes the paper feed to the first dot-line of the next character line to be printed to occur entirely in the reversing period.

Paper feed control for a dot-line printer

An auxiliary ribbon separator for use on a dot-line printer is positioned to prevent vertical ribbon displacement in the presence of upward forces such as caused by perforations on continuous feed paper. The auxiliary separator is located so that the ribbon is guided past an end of a front yoke. The front yoke serves as a course ribbon guide and is a component of the electro-magnetic assembly of the print head associated with the printer. The auxiliary separator may be shaped so as to facilitate loading of the ribbon in the printer.

Apparatus for preventing the rise of an ink ribbon

In a printing apparatus having a platen, a plurality of print hammers arranged in a horizontal row and a horizontally movable type carrier on which print carriers are arranged, a restraining member limits upward movement of a horizontally movable ink ribbon and thereby eliminates character omission. Between the print hammers and the type carriers are disposed the horizontally movable ink ribbon and a vertically movable print sheet on which a character impression is made upon impact of a selectively energized hammer. The print sheet is folded along transverse cut lines to define forms which are stacked together below the apparatus. When the print sheet is pulled upwardly, the folded portion tends to drag the ink ribbon upwardly displacing the ribbon from its print position. The restraining member is mounted above the ink ribbon to limit this upward movement of the ribbon.

Printing apparatus with inked ribbon lift restrainer

A sleeve member of elastomeric material is mounted on one of the driving and driven pulleys between which the type-carrier is passed. The sleeve member is wetted with a lubricant liquid so that a friction occurring between the type-carrier and the platen is minimized.

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Katsuta, Japan

Toshio Hiki