Abstract: A motor has a plurality of excitation coils, a commutator having a plurality of segments, a plurality of supply brushes and a short-circuit line. Each coil is connected to corresponding ones of the segments. The supply brushes include a plurality of supply brushes each having one of an anode and a cathode. At least one supply brush has the other one of an anode and a cathode. The supply brushes each simultaneously contact different one of the segments. The short-circuit line short-circuits segments that simultaneously contact the supply brushes of the same pole. The supply brushes of the same pole separate from the short-circuited segments at different times.

Abstract: A core includes a ring body and a plurality of teeth. The teeth extend radially outward form the outer circumference of the ring body. The core is formed by assembling a first core member and a second core member. Each core member has part of the teeth the number of which is half the total number of the teeth. Each tooth includes a tooth body about which the coil is wound, and a magnetism converging portion provided at the distal end of the tooth body. The tooth height of each tooth body gradually increases from a distal section to a proximal section of the tooth body. The tooth width gradually decreases from the distal section to the proximal section. The wire is wound about each of the teeth of the first and second core members. Then, the first and second core members are assembled to form the core. Accordingly, a rotor core having a high coil accommodation efficiency and a high coil space factor is obtained.

Abstract: A motor includes a commutator, which has twenty-four segments. Each of eight short-circuit members is connected to three of the segments. Each short-circuit member extends in an arcuate form in an angular range corresponding to arranging positions of three segments to be connected to the short-circuit member. The eight short-circuit members are laminated to form a multiple-layer structure in the axial direction of the commutator. The short-circuit members form a substantially cylindrical laminated body. The short-circuit members are formed and arranged such that the number of the layers of the laminated body is less than the number of the short-circuit members. As a result, the axial dimension of the laminated body is reduced and the miniaturization of the motor in the axial direction is achieved.

Abstract: A motor has twenty-four segments and a commutator. Each of eight short-circuit members short-circuits three of the segments with one another. Each short-circuit member includes an annular base portion and three arms radially extending from the base portion. Each arm is connected to one of the three segments to be short-circuited. Each arm has a segment connection portion at the distal end. The segment connection portion is connected to the corresponding segment. The base portions are laminated in the axial direction of the commutator such that the short-circuit members form a laminated body. The arms are formed such that all the segment connection portions are located in the same position with respect to the axial direction of the laminated body. As a result, the manufacture of the motor is facilitated.

Abstract: A motor includes a commutator, which has twenty-four segments. Each of eight short-circuit members is connected to three of the segments. Each short-circuit member extends in an arcuate form in an angular range corresponding to arranging positions of three segments to be connected to the short-circuit member. The eight short-circuit members are laminated to form a multiple-layer structure in the axial direction of the commutator. The short-circuit members form a substantially cylindrical laminated body. The short-circuit members are formed and arranged such that the number of the layers of the laminated body is less than the number of the short-circuit members. As a result, the axial dimension of the laminated body is reduced and the miniaturization of the motor in the axial direction is achieved.

Abstract: A motor includes a stator having magnets, a rotor having teeth, a commutator secured to the rotor, and brushes. A coil is wound about each tooth. The commutator is connected to the coils. The brushes slidably contact the commutator. The number of the magnets and the number of the teeth are determined such that the resultant of torque vectors that act on the teeth is zero. For example, the number of the magnet is six, and the number of the teeth is eight. As a result, the rotor is prevented from vibrating.

Abstract: The present invention provides a photopolymerizable composition useful as a liquid photoimageable solder mask comprising (a) a reaction product obtained by reacting epoxy resin A containing at least two terminated epoxy groups with 0.8 to 1.2 mol, per 1 epoxy equivalent of epoxy resin A, of an .alpha.,.beta.-unsaturated carboxylic acid and then reacting same with 0.2 to 1.0 mol, per 1 epoxy equivalent of epoxy resin A, of polybasic acid anhydride, (b) diluent, (c) sensitizer, (d) epoxy resin B consisting of tris (2,3-epoxypropyl) isocyanurate whose melting point is 130.degree. C. or less, and (e) an epoxy resin curing agent represented by the general formula [I:] ##STR1## wherein R is --H, halogen, --NH.sub.2, --SH, aromatic hydrocarbon, a C.sub.1 -C.sub.4 alkyl group or NHR' (R' is a C.sub.1 -C.sub.4 alkyl group having --CN or NH.sub.2 C.dbd.NH).