Tohoku Ricoh Co., Ltd.

Ricoh Company, Ltd.

Yoshiyuki Shishido

Satoshi Katoh

Yasumitsu Yokoyama

Yasunobu Kidoura

Akira Saito

Hisahiro Kamata

Hiroyuki Hiratsuka

Yukitaka Watarai

Yusuke Nemoto

Masakazu Fujita

Yoshihiko Kudoh

Susumu Shirauchi

Shin-ichi Shoji

An inverter device applies an excitation current to an excitation winding of a step-up transformer through a switching element, and outputs an output voltage with an alternating-current half-wave waveform from an output winding of the step-up transformer. The inverter device includes: an input-voltage detecting unit that detects a state of the input voltage, as a voltage; a current detecting unit that converts a current flowing through the switching element into a voltage to detects the current; and a comparing unit that compares a detected current value detected by the current detecting unit with a detected input voltage value detected by the input-voltage detecting unit, and detects a high-current period in which the detected current value exceeds the detected input voltage value. Based on information indicating the high-current period detected by the comparing unit, the control circuit adjusts a period in which the switching element is turned on.

Inverter device

An image-forming apparatus includes a head unit configured to include line-type recording heads for ejecting ink droplets, a transport mechanism disposed facing the recording head and configured to transport a sheet, a maintain-recovery mechanism disposed downstream from the transport mechanism in a direction in which the sheet is transported and configured to maintain and recover the line type recording heads, and a head drive mechanism configured to move the head unit between a position facing the transport mechanism and a position facing the maintain-recovery mechanism in the direction in which the sheet is transported.

Image forming apparatus

A stencil printer of the present invention perforates, or cuts, a thermosensitive stencil with a thermal head to thereby make a master. The stencil printer includes a stencil distinguishing device for automatically identifying the kind of the stencil or a master setting device for allowing the operator of the printer to set the kind of the stencil. An adjusting device selects, among master making conditions experimentally determined beforehand, a master making condition matching with information output from the stencil distinguishing device or the stencil setting device. The operator can easily change the master making condition in accordance with the kind of a stencil to use.

Stencil printer

A thermal master making device and a thermal printer including the same are disclosed. A thermistor senses ambient temperature around a thermal head. A correcting device corrects the amount of heat to be generated by the thermal head, i.e., the duration of energization at least two times during a single master making operation. This configuration reduces a change in the perforation conditions of a thermosensitive medium ascribable to the heat accumulation characteristic of the head. The printer achieves high resolution, high-speed master making and space saving.

Thermal master making device and thermal printer including the same

A master making device includes a thermal head with heat generating elements and a platen roller. While the head and platen roller convey a thermosensitive medium in a subscanning direction perpendicular to a main scanning direction, the heat generating elements selectively generate heat in order to perforate the medium in accordance with an image signal. The head includes a stepped portion formed at a medium outlet side in the subscanning direction. The edges of the heat generating elements adjoining the medium outside side are located at a distance of 0.018 mm to 0.5 mm from the end of the stepped portion adjoining the above edges. It is not necessary to position the head with respect to an effective nip between it and the platen roller by a troublesome procedure. Further, the distance over which the perforated medium is conveyed is reduced to obviate the reduction or contraction of an image ascribable to the sticking of the medium to the head.

Device for making a master

A thermal master making device includes a thermal head having a plurality of heating elements arranged in an array in the main scanning direction. The thermal head is caused to contact a stencil including a thermoplastic resin film. While the master is fed at a preselected feed pitch in the subscanning direction perpendicular to the main scanning direction, the heating elements selectively heat and perforate the film of the stencil in accordance with image data to thereby form an image in the stencil in the form of a dot pattern. A pitch at which the heating elements are arranged and the feed pitch are substantially equal to each other. The heating elements each have a length in the subscanning direction smaller than one-half of the feed pitch inclusive and have a length in the main scanning direction greater than the length in the subscanning direction. The device is capable of stably forming desired perforations in the stencil and extending the life of the heating element and therefore the life of the head. In addition, the device needs a minimum of master making time and therefore operates at a high speed.

Thermal master making device

A thermal master making device and a thermal recording device each including a thermal head and a platen roller. The master making device thermally perforates, or cuts, a thermosensitive stencil for making a master while the recording device thermally records an image on a thermosensitive recording medium. The devices each reduce the corrosion of an expensive thermal head in any environmental conditions while guaranteeing the conveyance of the stencil or the recording medium. The stencil and recording medium each contain a corrosive substance in an antistatic agent or adhesive or an overcoat layer thereof. The corrosion of the head would directly translate into defective images. With the above devices, it is possible to reduce a burden on the user and to extend the life of the head. Extending the life of the head is desirable from the environmental standpoint also.

Thermal master making device and thermal recording device

A control device for a thermosensitive stencil printer capable of perforating a stencil in an optimal configuration matching a desired resolution in the subscanning direction and thereby producing desirable images. The device allows perforations to be formed in a stencil in an adequate size in the subscanning direction. Heating portions included in a thermal head are each sized, in the subscanning direction, smaller than a feed pitch corresponding to the highest resolution available with a resolution setting device.

Control device for a thermosensitive stencil printer

A control device for a thermosensitive stencil printer which is capable of perforating a stencil in an optimal configuration matching a desired resolution in the subscanning direction and thereby producing desirable images. The device allows perforations to be formed in a stencil in an adequate size in the subscanning direction. Heating portions included in a thermal head are each sized, in the subscanning direction, smaller than a feed pitch corresponding to the highest resolution available with a resolution setting device.

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Miyagi, Japan

Yoshiyuki Shishido