Abstract: The projection zoom lens system includes a negative first lens group, a positive second lens group, a third lens group, a positive fourth lens group, a fifth lens group, and a positive sixth lens group. The lens system is nearly telecentric on a reduction side. During zooming, the second to fifth lens groups are moved while the first and six lens groups remain stationary. The third lens group includes a positive lens LP having a convex surface directed to a magnification side, and a negative lens LN having a concave surface which is directed to the reduction side and has a curvature stronger than a magnification-side surface of the negative lens LN. The conditional expression of 5.0?|fG3/RLN-2| is satisfied. Here, fG3 denotes a focal length of the third lens group, and RLN-2 denotes a radius of curvature of the reduction-side surface of the negative lens LN.

Abstract: Disclosed are a projection lens that has a small size, a simple inner focus structure, a high optical performance, and a wide angle of view of about 75 degrees or more, and a projection display device. A projection lens includes a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power arranged in this order from a magnification side. A fifth lens arranged closest to a reduction side in the first lens group is moved along an optical axis to adjust focus. The projection lens satisfies the following conditional expression: 3.0<DG12/f<6.0 where DG12 indicates a distance between the first lens group and the second lens group and f indicates the focal length of the entire lens system.

Abstract: Disclosed are a projection lens that is faster than F1.95 and has a simple inner focus structure, a high optical performance, and a small size, and a projection display device. A projection lens includes a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power arranged in this order from a magnification side. A fifth lens arranged closest to a reduction side in the first lens group is moved along an optical axis to adjust focus. The projection lens satisfies the following conditional expression: 0.2<DG12/f<0.8 where DG12 indicates a distance between the first lens group and the second lens group and f indicates the focal length of the entire lens system.

Abstract: Disclosed are a projection lens that has a simple inner focus structure, an appropriate back focal length, telecentricity, a high optical performance, and a small size and can effectively correct, particularly, lateral chromatic aberration, and a projection display device. A projection lens includes a first lens group having a negative refractive power and a second lens group having a positive refractive power arranged in this order from a magnification side. A fifth lens arranged closest to a reduction side in the first lens group is moved along an optical axis to adjust focus, and at least two lenses are made of a material satisfying the following conditional expression: 0.018<??(?0.00164·?d+0.6427)<0.06 (where ?=(ng?nF)/(nF?nC), ?d=(nd?1)/(nF?nC), and ng, nF, nd, and nC indicate refractive indexes with respect to the g-line, the F-line, the d-line, and the C-line, respectively).

Abstract: To provide an internal gear pump capable of preventing small vibrations due to pressure differences at the outlet port side of a crescent disposed between the outer rotor and the inner rotor, so that fatigue failure does not occur in the crescent over a long time period, whereby the durability can be increased. The internal gear pump includes a rotor unit, in which an inner rotor is disposed within an outer rotor on the inner peripheral side and a crescent is disposed in the gap between the inner rotor and the outer rotor, the rotor unit being housed in a pump casing. Outer cells are formed by the crescent and the outer rotor. Inner cells are formed by the crescent and the inner rotor. Linking of the outer cells and the outlet port, and linking of the inner cells 6 and the outlet port, start substantially simultaneously.

Abstract: The projection zoom lens system includes a negative first lens group, a positive second lens group, a third lens group, a positive fourth lens group, a fifth lens group, and a positive sixth lens group. The lens system is nearly telecentric on a reduction side. During zooming, the second to fifth lens groups are moved while the first and six lens groups remain stationary. The third lens group includes a positive lens LP having a convex surface directed to a magnification side, and a negative lens LN having a concave surface which is directed to the reduction side and has a curvature stronger than a magnification-side surface of the negative lens LN. The conditional expression of 5.0?|fG3/RLN?2| is satisfied. Here, fG3 denotes a focal length of the third lens group, and RLN?2 denotes a radius of curvature of the reduction-side surface of the negative lens LN.

Abstract: The present invention enables the manufacture of a trochoid pump having a crescent which has been considered theoretically impossible by employing an inner rotor of a trochoid pump. An inner rotor having a predetermined number N of teeth that is equal to or larger than 4 is formed in advance.

Abstract: A projection zoom lens device includes, in order from a magnification side, a negative first group G1 and positive second to fifth groups (G2 to G5) and is configured so that the second group G2, the third group G3, and the fourth group G4 are moved along an optical axis toward the magnification side during zooming from a wide-angle end state to a telephoto end state. Also, a lens L4, being closest to the magnification side, of the second group G2 is formed of a negative lens, and the fifth group G5 includes a single positive lens.

Abstract: To provide an internal gear pump capable of preventing small vibrations due to pressure differences at the outlet port side of a crescent disposed between the outer rotor and the inner rotor, so that fatigue failure does not occur in the crescent over a long time period, whereby the durability can be increased. The internal gear pump includes a rotor unit, in which an inner rotor is disposed within an outer rotor on the inner peripheral side and a crescent is disposed in the gap between the inner rotor and the outer rotor, the rotor unit being housed in a pump casing. Outer cells are formed by the crescent and the outer rotor. Inner cells are formed by the crescent and the inner rotor. Linking of the outer cells and the outlet port, and linking of the inner cells 6 and the outlet port, start substantially simultaneously.

Abstract: A trochoidal oil pump which makes it possible to achieve an improved reduction in discharge pulsation and noise, and which makes it possible to realize such a reduction using an extremely simple structure. The trochoidal oil pump of the present invention comprises a rotor chamber 1 which has an intake port 2 and discharge port 3, an outer rotor 6 and an inner rotor 5. A plurality of inter-tooth spaces S, S, . . . that are formed by the tooth shapes 5a and 6a of the inner rotor 5 and outer rotor 6 comprise a maximum sealed space Smax that is positioned in the region of the partition part 4 between the intake port 2 and discharge port 3, a plurality of inter-tooth spaces S, S, . . . within the region of the intake port 2, and a plurality of inter-tooth spaces S, S, . . . within the region of the discharge port 3. The plurality of inter-tooth spaces S, S, . . .

Abstract: To reduce noise caused by pulsation generated when fluid is expelled, in a trochoidal pump comprising an inner rotor and outer rotor having trochoidal toothed shapes. [Means of Solution] The inner rotor 5 and outer rotor 6 having trochoidal toothed shapes are set in such a manner that when they are in a mutually intermeshing state, a tip clearance d0 is created between the respective tooth crests 5a of the inner rotor 5 and the outer rotor 6. In at least one position of this group of tip clearances d0, a large clearance d1 forming a large interval is provided.

Abstract: A trochoidal oil pump which makes it possible to achieve an improved reduction in discharge pulsation and noise, and which makes it possible to realize such a reduction using an extremely simple structure. The trochoidal oil pump of the present invention comprises a rotor chamber 1 which has an intake port 2 and discharge port 3, an outer rotor 6 and an inner rotor 5. A plurality of inter-tooth spaces S, S, . . . that are formed by the tooth shapes 5a and 6a of the inner rotor 5 and outer rotor 6 comprise a maximum sealed space Smax that is positioned in the region of the partition part 4 between the intake port 2 and discharge port 3, a plurality of inter-tooth spaces S, S, . . . within the region of the intake port 2, and a plurality of inter-tooth spaces S, S, . . . within the region of the discharge port 3. The plurality of inter-tooth spaces S, S, . . .

Abstract: To reduce noise caused by pulsation generated when fluid is expelled, in a trochoidal pump comprising an inner rotor and outer rotor having trochoidal toothed shapes.