Abstract: A method for producing a surface-treated carbon black particle aqueous dispersion that exhibits excellent blackness and dispersibility, exhibits excellent storage stability, suppresses feathering, exhibits an excellent discharge capability and rubfastness (quick-drying capability), and suppresses metal corrosion when used in an aqueous black pigment (colorant) ink, is disclosed. The method for producing a surface-treated carbon black particle aqueous dispersion includes providing an aqueous dispersion of oxidized carbon black particles obtained by forming acidic hydroxyl groups on a surface of carbon black particles having a DBP absorption of 120 cm3/100 g or more, neutralizing 5% or more and less than 50% of the acidic hydroxyl groups with a polyvalent cation, and neutralizing the remainder of the acidic hydroxyl groups with a monovalent cation.

Abstract: A method for producing a surface-treated carbon black particle aqueous dispersion that exhibits excellent blackness and dispersibility, exhibits excellent storage stability, suppresses feathering, exhibits an excellent discharge capability and rubfastness (quick-drying capability), and suppresses metal corrosion when used in an aqueous black pigment(colorant) ink, is disclosed. The method for producing a surface-treated carbon black particle aqueous dispersion includes providing an aqueous dispersion of oxidized carbon black particles obtained by forming acidic hydroxyl groups on a surface of carbon black particles having a DBP absorption of 120 cm3/100 g or more, neutralizing 5% or more and less than 50% of the acidic hydroxyl groups with a polyvalent cation, and neutralizing the remainder of the acidic hydroxyl groups with a monovalent cation.

Abstract: A radio apparatus includes a plurality of receiving systems connected to multiple antennas providing diversity, respectively, each receiving system including an antenna terminator and a preamplifier. After one receiving system is discriminated from another receiving system based on radio signals received by the receiving systems, respectively, a controller controls the one receiving system such that an antenna terminator is inactive and a preamplifier is active and, at the same time, further controls the other receiving system such that an antenna terminator is active and a preamplifier is inactive.

Abstract: A radio apparatus includes a plurality of receiving systems connected to multiple antennas providing diversity, respectively, each receiving system including an antenna terminator and a preamplifier. After one receiving system is discriminated from another receiving system based on radio signals received by the receiving systems, respectively, a controller controls the one receiving system such that an antenna terminator is inactive and a preamplifier is active and, at the same time, further controls the other receiving system such that an antenna terminator is active and a preamplifier is inactive.

Abstract: A planar antenna includes a ground plate and a conductive plate arranged in parallel to the ground plate. The conductive plate has a ground terminal at a first position thereof and has a feed terminal at a second position thereof. The planar antenna further includes a frequency change switch which is used to charge the antenna resonance frequency by electrically connecting the conductive plate to the ground plate at a third position which is different from the first and second positions.

Abstract: A helical antenna is provided for portable radio apparatus characterized in having one communication band switch and having two separated communication bands, or a broad communication band. The helical antenna comprises a screw shaped emitting element having one power supply terminal and two communication band switching terminals, a switch which short circuits and disconnects the two communication band switching terminals, and a switch drive circuit which drives this switch, and in accordance with an externally applied signal, the switch drive circuit short circuits or disconnects the switch, and by means of the disconnection or short circuiting of the two communication band switching terminals, the resonance frequency is switched.

Abstract: An optical star coupler that distributes the optical signal radiated from an optical fiber uniformly across the mixing means and couples the distributed optical signal efficiently to the other optical fibers. The optical star coupler includes: a bundling means including a plurality of optical fibers, the ends thereof being bundled, a flat plane formed by polishing the end faces of the optical fibers, and a light reflector formed on a part of the flat plane; a mixing means including a waveguide, the first end face thereof contacting with the flat plane and wide enough to cover the cores of the optical fibers; and a diffuser-reflector means arranged on the second end face of the waveguide.

Abstract: A light beam from an optical fiber held by a waveguide support is guided to an illuminated region of a light-receiving section. A light beam from one light-deflecting device inside this region is reflected by a reflecting surface and passed as a light beam through a second light-deflecting device in another illuminated region to arrive at a second optical fiber. A light beam from the second optical fiber takes the reverse route to the foregoing route. In this way, various light-deflecting devices in one illuminated region are optically coupled to light-deflecting devices in other illuminated regions with substantially equal optical coupling strength. Further for equalizing light-beam intensities and minimizing optical dispersion loss, lenses may be included with the light-deflecting devices.

Abstract: A light beam from an optical fiber held by waveguide support is guided to an illuminated region of a light-receiving section. A light beam from one light-deflecting device inside this region is reflected by a reflecting surface and passed as a light beam through a second light-deflecting device in another illuminated region to arrive at a second optical fiber. A light beam from the second optical fiber takes the reverse route to the foregoing route. In this way, various light-deflecting devices in one illuminated region are optically coupled to light-deflecting devices in other illuminated regions with substantially equal optical coupling intensity.