Abstract: A ceramic substrate comprises having two or more functional portions separated from each other, by providing a first region comprising a first dielectric porcelain having an insulating layer at the crystal grain boundaries of a semiconductor porcelain containing a semiconductivizing agent and a second region comprising a second dielectric porcelain with different dielectric constant from the first dielectric porcelain through the difference in amount or kind of the semiconductivizing agent from the first region.

Abstract: A camera includes a fixed first mirror for both reflecting a light flux and transmitting the light flux therethrough, a second mirror for reflecting a part of the light flux transmitted through the first mirror toward a particular device, the second mirror being capable of moving between a non-exposure position and a mirror-retracted position, and a light blocking member movable in interlocked relationship to a movement of the second mirror in such a manner that, when the second mirror is located at the non-exposure position, the light blocking member is located at a light blocking position at which the light blocking member blocks at least a part of the light flux transmitted through the first mirror, and, when the second mirror is retracted to the mirror-retracted position, the light blocking member moves to a retracted position at which the light blocking member is retracted from the light blocking position.

Abstract: A ceramic substrate comprises having two or more functional portions separated from each other, by providing a first region comprising a first dielectric porcelain having an insulating layer at the crystal grain boundaries of a semiconductor porcelain containing a semiconductivizing agent and a second region comprising a second dielectric porcelain with different dielectric constant from the first dielectric porcelain through the difference in amount or kind of the semiconductivizing agent from the first region.

Abstract: The present invention provides a ceramic having a first region comprising a dielectric porcelain having an insulating layer at the crystal grain boundary of a semiconductor porcelain containing 0.50 to 5.30 mol parts of MnO.sub.2 and 0.02 to 0.40 mol parts of Y.sub.2 O.sub.3 per 100 mol parts of the principal components comprising 49.50 to 54.00 mol % of TiO.sub.2 and 50.50 to 46.00 mol % of SrO, and a second region comprising a dielectric porcelain containing further 0.40 to 5.00 mol parts of MgO and 0.05 to 2.00 mol parts of SiO.sub.2 per 100 mol parts of the principal components in addition to the composition of the first region, and also provides a circuit substrate and an electronic circuit substrate using the same ceramic.

Abstract: The present invention provides a ceramic having a first region comprising a dielectric porcelain having an insulating layer at the crystal grain boundary of a semiconductor porcelain containing 0.50 to 5.30 mol parts of MnO.sub.2 and 0.02 to 0.40 mol parts of Y.sub.2 O.sub.3 per 100 mol parts of the principal components comprising 49.50 to 54.00 mol. % of TiO.sub.2 and 50.50 to 46.00 mol. % of SrO, and a second region comprising a dielectric porcelain containing further 0.40 to 5.00 mol parts of Al.sub.2 O.sub.3 and 0.05 to 2.00 mol parts of SiO.sub.2 per 100 mol parts of the principal components in addition to the composition of the first region, and also provides a circuit substrate and an electronic circuit substrate using the same ceramic.

Abstract: A ceramic comprising a first region comprises a dielectric porcelain having an insulating layer at the crystal grain boundary of a semiconductor porcelain containing 0.50-5.30 mol parts of MnO.sub.2 and 0.02-0.40 mol parts of Y.sub.2 O.sub.3 per 100 mol parts of a principal components consisting of 49.50-54.00 mol % of TiO.sub.2 and 50.50-46.00 mol % of SrO, and a second region comprising a dielectric porcelain containing further 0.40-5.00 mol parts of Al.sub.2 O.sub.3, based on 100 mol parts of said principal components, in addition to the composition of the first region.

Abstract: A ceramic comprises a first region comprising a dielectric porcelain having an insulating layer at the crystal grain boundary of a semiconductor porcelain containing 0.50-5.30 mol parts of MnO.sub.2 and 0.02-0.40 mol parts of Y.sub.2 O.sub.3 per 100 mol parts of a principal components consisting of 49.50-54.00 mol % of TiO.sub.2 and 50.50-46.00 mol % of SrO, and a second region comprising a dielectric porcelain containing further 0.40-5.00 mol parts of M.sub.g O, based on 100 mol parts of said principal components, in addition to the composition of the first region.

Abstract: A ceramic-forming composition comprises from 2.0 to 5.0 mol parts of MnO.sub.2 and from 0.05 to 0.30 mol part of Y.sub.2 O.sub.3 based on 100 mol parts of a main component comprising from 50.20 to 53.50 mol % of TiO.sub.2 and from 49.80 to 46.50 mol % of SrO. A semiconductor porcelain substrate, a dielectric porcelain substrate and a capacitor are produced by using the same ceramic-forming composition.

Abstract: The present invention provides a ceramic having a first region comprising a dielectric porcelain having an insulating layer at the crystal grain boundary of a semiconductor porcelain containing 0.50 to 5.30 mol parts of MnO.sub.2 and 0.02 to 0.40 mol parts of Y.sub.2 O.sub.3 per 100 mol parts of the principal components comprising 49.50 to 54.00 mol % of TiO.sub.2 and 50.50 to 46.00 mol % of SrO, and a second region comprising a dielectric porcelain containing further 0.40 to 5.00 mol parts of Al.sub.2 O.sub.3 and 0.05 to 2.00 mol parts of SiO.sub.2 per 100 mol parts of the principal components in addition to the composition of the first region, and also provides a circuit substrate and an electronic circuit substrate using the same ceramic.

Abstract: A ceramic comprises a first region comprising a dielectric porcelain having an insulating layer at the crystal grain boundary of a semiconductor porcelain containing 0.50-5.30 mol parts of MnO.sub.2 and 0.02-0.40 mol parts of Y.sub.2 O.sub.3 per 100 mol parts of a principal components consisting of 49.50-54.00 mol % of TiO.sub.2 and 50.50-46.00 mol % of SrO, and a second region comprising a dielectric porcelain containing further 0.40-5.00 mol parts of MgO, based on 100 mol parts of said principal components, in addition to the composition of the first region.

Abstract: The present invention provides a ceramic having a first region comprising a dielectric porcelain having an insulating layer at the crystal grain boundary of a semiconductor porcelain containing 0.50 to 5.30 mol parts of MnO.sub.2 and 0.02 to 0.40 mol parts of Y.sub.2 O.sub.3 per 100 mol parts of the principal components comprising 49.50 to 54.00 mol% of TiO.sub.2 and 50.50 to 46.00 mol% of SrO, and a second region comprising a dielectric porcelain containing further 0.40 to 5.00 mol parts of MgO and 0.05 to 2.00 mol parts of SiO.sub.2 per 100 mol parts of the principal components in addition to the composition of the first region, and also provides a circuit substrate and an electronic circuit substrate using the same ceramic.

Abstract: A ceramic comprising a first region comprises a dielectric porcelain having an insulating layer at the crystal grain boundary of a semiconductor porcelain containing 0.50-5.30 mol parts of MnO.sub.2 and 0.02-0.40 mol parts of Y.sub.2 O.sub.3 per 100 mol parts of a principal components consisting of 49.50-54.00 mol % of TiO.sub.2 and 50.50-46.00 mol % of SrO, and a second region comprising a dielectric porcelain containing further 0.40-5.00 mol parts of Al.sub.2 O.sub.3, based on 100 mol parts of said principal components, in addition to the composition of the first region.

Abstract: A ceramic comprises therein two or more dielectric portions having different dielectric constants formed by filling of one or more vacant spaces provided within a dielectric porcelain, a semiconductor porcelain as a precursor of said dielectric porcelain or a molded product as a precursor of said semiconductor procelain with one or more kinds of materials capable of becoming to have different dielectric constants from said dielectric porcelain and subsequent calcination.

Abstract: A composition for semiconductor porcelain comprisies:(a) 35.5 to 70 mol % of MgTiO.sub.3,(b) 26.5 to 61 mol % of BaTiO.sub.3,(c) a grain boundary improver, and(d) 0.01 to 0.2 mol % of an element selected from rare earth elements and the elements belonging to the group V of the periodic table.

Abstract: A functional substrate is produced by forming a diffusion source for fabricating an electronic part in a ceramic substrate which has been made semiconductive by a sintering and subjecting the ceramic substrate to a firing to give plural electronic-part-forming units, isolated from one another, in the ceramic substrate. An electronic circuit comprises the functional substrate and at least electrodes for the electronic-part-forming units.