Abstract: A two-lens-group zoom lens system includes a positive first lens group and a negative second lens group in this order from the object, and zooming is performed by varying the distance between the first and the second lens groups. The positive first lens group includes a negative first lens element, a plastic-made second lens element having at least one aspherical surface, and a positive third lens element in this order from the object. The zoom lens system satisfies the following conditions: 3.5<fT/f1G<4.5  (1) −4.7<fT/f2G<−3.7  (2) 63<&ngr;DL3  (3) wherein fT designates the focal length of the entire zoom lens system at the long focal length extremity; f1G designates the focal length of the positive first lens group; f2G designates the focal length of the negative second lens group; and &ngr;dL3 designates the Abbe number with respect to the positive third lens element in the positive first lens group.

Abstract: A zoom lens system including a first through third lens groups. The combined power of the first and second lens groups is positive. Upon zooming from the short focal length extremity towards the long focal length extremity, all the three lens groups are moved from the image towards the object.

Abstract: In a short-focal-length side zooming range, a moveable sub-lens group of a zoom lens system is made stationary at one of the object-side and the image-side end. At the intermediate switching focal length, the moveable sub-lens group is moved to the other of the object-side and the image-side end.

Abstract: A vortex prevention apparatus is combined with a pump, and prevents an air entrained vortex or a submerged vortex from being produced when water in the pump pit is pumped up by a pump. A suction member is disposed in an open water channel and has a suction port. An auxiliary flow-path forming structure is disposed substantially concentrically around the suction member with a gap defined between the auxiliary flow-path forming structure and an outer circumferential surface of the suction member.

Abstract: A zoom lens system includes a first lens group, a second lens group, and a third lens group, in this order from the object. Zooming is performed by moving the first through third lens groups. The zoom lens system satisfies the following conditions: 1 0.62 < ( d T12 - d W12 ) / f W < 1.

Abstract: A zoom lens system including a positive first lens group and a negative second lens group, in this order from the object, wherein zooming is performed by varying the distance between the first lens group and the second lens group. The positive first lens group includes a negative first sub-lens-group, a positive second sub-lens-group, and a positive third sub-lens-group, in this order from the object, wherein the zoom lens system satisfies the following condition: 0.7<fT/f1-2<1.5  (1) wherein fT designates the focal length of the entire zoom lens system at the long focal length extremity; and f1-2 designates the focal length of the positive second sub-lens-group in the first lens group.

Abstract: A vacuum envelope of a cathode ray tube comprises a faceplate and a rear envelope bonded to the faceplate. The rear envelope includes a rear plate opposed to the faceplate, a side wall, a plurality of funnels extending from the rear plate, partition walls set up on the rear plate, and necks bonded individually to the funnels. The rear envelope is formed by connecting a plurality of miniature envelopes to one another. Each miniature envelope includes at least one funnel, and is molded by pressing.

Abstract: A zoom lens system includes a positive first lens group and a negative second lens group, in this order from the object. Zooming is performed by varying the distance between the first lens group and the second lens group. The positive lens group includes a negative 1-a sub lens group and a positive 1-b sub lens group, in this order from the object, and the zoom lens system satisfies the following conditions: 0.4<fW/|f1-a|<0.7  (1) 0.07<da-b/fW<0.14  (2) 4<fT/f1-b<6  (3) wherein fW designates the entire focal length at the short focal length extremity; f1-a designates the focal length of the 1-a sub lens group (f1-a<0); da-b designates the distance between the 1-a sub lens group and the 1-b sub lens group; fT designates the focal length of the entire the zoom lens system at the long focal length extremity; and f1-b designates the focal length of the 1-b sub lens group.

Abstract: A needle selector for knitting machines is provided, which includes a finger actuating device, a power supply means for feeding electric power to the finger actuating device, and power supply terminals for supplying power to the power supply means, wherein said finger actuating device fast and steadily operates piezoelectric bodies 7 including piezoelectric elements by bending them while supporting the piezoelectric bodies 7 at the tip, rear end and a prescribed position between the tip and the rear end, and using a power supply means including of bar-shaped electrodes 28 each including at least two conductive parts with an insulating part in-between, resulting in a substantial reduction in size.

Abstract: A zoom lens system including a positive first lens group and a negative second lens group in this order from the object, and in which zooming is performed by varying the distance between the positive first lens group and the negative second lens group; wherein a diaphragm is positioned between lens elements which constitute the first lens group, and wherein focusing is performed by moving the negative second lens group along the optical axis.

Abstract: A zoom lens system having a positive first lens group and a negative second lens group in this order from the object side, wherein zooming is performed by varying the distance between the first and the second lens groups. The zoom lens system satisfies the following conditions (1) and (2): 1.4<fw/f1G<1.7  (1) 0.85<&Sgr;d1G/fw<1.1  (2) wherein: fw designates the focal length of the zoom lens system at the short focal length extremity; and f1G designates the focal length of the positive first lens group; and &Sgr;d1G designates the thickness of the positive first lens group.

Abstract: A copolymer having (I) a repeating unit derived from a monomer having a fluorine atom and (II) repeating unit derived from a fluorine-free monomer having at least one urethane or urea linkage and one carbon—carbon double bond, gives excellent water- and oil-repellency and is dissolved in an alcohol solvent.

Abstract: A zoom lens system including a positive first lens group and a negative second lens group in this order from the object side, wherein the distance between the first and second lens groups is varied upon zooming. A middle or rear portion of the positive first lens group is formed as a focusing lens group so that the focusing lens group can be moved along the optical axis without changing the distance between the most-object side lens surface of the first positive lens group and the image plane when focusing is performed.

Abstract: An envelope of a cathode ray tube includes a substantially rectangular flat face plate, and a substantially rectangular flat rear plate opposed to the face plate with a side wall being interposed therebetween, a plurality of funnels extending from the rear plate. A plurality of necks extend from the respective funnels, and a plurality of electron guns are respectively arranged in the necks. A plurality of plate support portions are arranged between the rear plate and the face plate, so as to support the rear plate and the face plate against an atmospheric pressure. Each plate support portion includes a support body made of glass which is integrally welded with the rear plate and extends from the rear plate toward the face plate, and a distal end portion jointed to the extending end of the support body and being in contact with the face plate.

Abstract: An optical modulation device is constituted by a first substrate provided with a plurality of first electrodes each comprising a plurality of portions electrically independent of each other, a second substrate disposed opposite to the first substrate and provided with a plurality of second electrodes each confronting a corresponding first electrode, and an optical modulation substance disposed between the first and second substrates so as to form a plurality of pixels each having a particular electrode structure. In the electrode structure, the optical modulation substance is sandwiched between each second electrode and said portions of said corresponding first electrode so as to form a series circuit providing a plurality of capacitance, thus reducing the capacitance for each pixel to improve a switching characteristic while minimizing a defective portion due to a short-circuit between the confronting electrodes.

Abstract: A zoom lens system which includes a positive first lens group and a negative second lens group, in this order from the object side; wherein zooming is performed by moving the first lens group and the second lens group, and by varying the distance between the first lens group and the second lens group; wherein the zoom lens system satisfies the following condition: −7.0<fT/f2G<−5.1 . . .   (1) wherein: fT designates the focal length of the entire lens system at the long focal-length extremity and f2G designates the focal length of the second lens group.

Abstract: A vacuum envelope includes a flat face plate having a phosphor screen formed on the inner surface of the face plate, and a flat rear plate opposed to the face plate with a side wall interposed therebetween. A plurality of funnels extend from the rear plate, and electron guns are respectively enclosed in the necks of the funnels. The rear plate and the plurality of funnels are integrally formed of one single plate glass and are joined to face plate through the side wall. A plurality of reference surfaces are formed on the inner surface of the rear plate, and ends of the plate support members are respectively fixed to the reference surfaces.

Abstract: A zoom lens system including a positive first lens group and a negative second lens group, in that order form the object. The positive first lens group includes, on the most-object side, a cemented sub lens group having a negative lens element and a positive lens element. The zoom lens system satisfies the following conditions, and the order of the lens elements in the cemented sub lens group is the negative lens element and positive lens element in this order from the object:-1.2<r1/fw<-0.3 (1)-2<fw/fc<-0.5 (2)8<.nu.N-.nu.P (3)Wherein r1 designates the radius-of-curvature of the most-object side surface of the cemented sub lens group; fw designates the focal length of the entire lens system at the short focal length extremity; fc designates the focal length of the cemented sub lens group; .nu.N designates the Abbe number of the negative lens element of the cemented sub lens group; and .nu.P designates the Abbe number of the positive lens element of the cemented sub lens group.

Abstract: A zoom lens system comprising at least three lens groups including a positive first lens group, a positive second lens group having at least one negative lens element, and a third lens group having a negative focal length, wherein upon zooming from the shortest focal length toward the longest focal length, all the lens groups are moved toward the object side, and the distance between the first and second lens groups increases and the distance between the second and third lens groups decreases, and wherein the system satisfies the conditions (1) -0.3<f.sub.W /f.sub.1G +f.sub.W /f.sub.2G +f.sub.W /f.sub.3G <0, and (2) 1.845<N.sub.2Gn, wherein f.sub.W designates the focal length of the entire optical system at the short focal length extremity, f.sub.1G designates the focal length of the first lens group (f.sub.1G >0), f.sub.2G designates the focal length of the second lens group (f.sub.2G >0), f.sub.3G designates the focal length of the third lens group (f.sub.3G <0), N.sub.

Abstract: A zoom lens system comprises a first lens group of positive power and a second lens group of negative power. The zoom lens system is arranged to perform a zooming operation by varying a distance between the first lens group and the second lens group. Furthermore, the first lens group comprises a front sub lens group of negative poser and a rear sub lens group of positive power. Still further, the front sub lens group comprises a first single lens element of negative power and a second single lens element having an aspherical surface on which the radius of curvature becomes larger in the off-axis region, and the rear sub lens group of the first lens group comprises a cemented lens having a positive lens element and a negative lens element. Moreover, the zoom lens system satisfies various conditions.