Hitachi Cable, Inc.

Hitachi, Ltd.

Hisao Iizuka

Kiyohiko Tanno

Hideo Hirane

Shigetoshi Hiratsuka

Norihiro Ashizuka

Teruji Satou

Hiroshi Kajioka

A driver IC of a light-emitting diode array head for an electronic photograph printer includes a current mirror circuit having a reference element and at least an output element so as to produce a reference current by use of a digital signal as an input thereto, a reference current source capable of outputting a plurality of reference current values, a selection circuit for specifying and selecting one of a plurality of reference current values from the reference current source, to be applied as an input current to the current mirror and an output control circuit for controlling the on and off states of an output current to be supplied to the output element of the current mirror circuit in accordance with a light emission control signal externally supplied. In connection with such a driver IC for a light-emitting diode array, there is implemented, furthermore, a bidirectional data scan with a reduced number of register circuits by employing in connection with n-data lines constituting a data bus, a group of register blocks each one thereof having n registers and which are operatively coupled so as to provide image data stored in the n registers to a plurality of driver circuits which switch ON/OFF the correspondingly associated light-emitting diodes. Furthermore, in connection with the register blocks, the driver also employs a bidirectional shift register for sequentially providing corresponding timing signals to each of the memory blocks.

Light-emitting element array driver circuit

A driver IC of a light-emitting diode array head for an electronic photograph printer includes a current mirror circuit having a reference element and at least an output element so as to produce a reference current by use of a digital signal as an input thereto, a reference current source capable of outputting a plurality of reference current values, a selection circuit for specifying and selecting one of a plurality of reference current values from the reference current source to be applied as an input current to the current mirror circuit, and an output control circuit for controlling the on and off states of an output current to be supplied to the output element of the current mirror circuit in accordance with a light emission control signal externally supplied. The output control circuit achieves a multi-stage control of the driver output current volume, which is to be delivered to the light emitting diodes, thereby facilitating the driving operation to correct the fluctuation in the light emission power of the light-emitting diode array and the change of the light emission power thereof with the lapse of time.

An optical printer head with a light emitting diode array comprises means for setting a distance between a light emitting surface of a light emitting diode array chip and a rod lens array. The means is provided with two reference position levels at which the light emitting diode array chip and the rod lens array are held. Therefore, there is no necessity for adjusting the distance between the light emitting diode array chip and the rod lens array so that a productivity thereof is much improved.

Optical printer head with a light emitting diode array

In a single-polarization fiber optics magnetic sensor comprising a light source, a Faraday rotation element, a photodetector, and optical waveguide means for optically coupling them; according to a first embodiment, the optical waveguide means comprises upstream and downstream polarization-maintaining optical fibers coupled to the entrance and exit of the Faraday rotation element without a polarizer or an analyzer interposed therebetween; according to a second embodiment, in addition thereto, the axis of polarization of the downstream polarization-maintaining optical fiber is at an angle of about 45 degrees with respect to the orientation of the linearly polarized light exiting from the Faraday rotation element at a magnetic field intensity H equal to 0; and according to a third embodiment, in addition thereto, a polarization beam splitter is located in alignment with the orientation of polarization of the exit light from the downstream polarization-maintaining optical fiber, and two polarized light beams produced by said beam splitter are received by two photo-detectors for subsequent signal computation.

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Hitachi, Japan

Hisao Iizuka