Abstract: An imaging lens includes a first lens L1 that has a biconvex shape near an optical axis and has positive refractive power, a second lens L2 that has a biconcave shape near the optical axis and has negative refractive power, a third lens L3 that has a shape of a meniscus lens directing a concave surface thereof to an object side near an optical axis and has positive refractive power, and a fourth lens L4 that has a biconcave shape near the optical axis and has negative refractive power, arranged in this order from the object side. When the whole lens system has a focal length f and the fourth lens L4 has a focal length f4, the imaging lens of the invention satisfies the following expression: ?0.7<f4/f<?0.1.

Abstract: An imaging lens includes a first lens having negative refractive power; a second lens having negative refractive power; a third lens; a fourth lens; and a fifth lens. The first lens has a positive curvature radius on an image plane side. The second lens has a sharp convex surface, and a positive curvature radius on the image plane side. The third lens has a positive curvature radius on the object side and a negative curvature radius on the image plane side. The fourth lens has a negative curvature radius on the object side and a positive curvature radius on the image plane side. The fifth lens has a positive curvature radius on the object side and a negative curvature radius on the image plane side, and an aspheric surface.

Abstract: An imaging lens includes an aperture stop ST, a first lens L1 that is shaped to form a meniscus lens that directs a convex surface to the object side near an optical axis and has positive refractive power, a second lens L2 that is shaped to form a meniscus lens that directs a convex surface to the object side near the optical axis and has negative refractive power, a third lens L3 that is shaped to form a meniscus lens that directs a concave surface to the object side near the optical axis and has positive refractive power, and a fourth lens L4 that is shaped to form a meniscus lens that directs a convex surface to the object side near the optical axis, arranged in this order from an object side to an image side. When the first lens L1 has a focal length f1 and the second lens L2 has a focal length f2, the imaging lens is configured such that a relationship 0.3<|f1/f2|<0.7 is satisfied.

Abstract: An imaging lens, although compact, has satisfactorily corrected aberrations. The imaging lens is configured by disposing, in sequence from the object side, a stop (ST); a first lens (L1), which has a double convex shape near the optical axis; a meniscus-shaped negative second lens (L2) which has near the optical axis a convex surface facing the object side; a meniscus-shaped positive third lens (L3) which has near the optical axis a concave surface facing the object side; and a positive fourth lens (L4) which has a double convex shape near the optical axis. In the configuration, the refractive power of the first lens (L1) is greater than the refractive power of each of the second lens (L2), the third lens (L3), and the fourth lens (L4).

Abstract: An imaging lens includes a first lens having negative refractive power; a second lens having negative refractive power; a third lens; a fourth lens; and a fifth lens. The first lens has a positive curvature radius on an image plane side. The second lens has a sharp convex surface, and a positive curvature radius on the image plane side. The third lens has a positive curvature radius on the object side and a negative curvature radius on the image plane side. The fourth lens has a negative curvature radius on the object side and a positive curvature radius on the image plane side. The fifth lens has a positive curvature radius on the object side and a negative curvature radius on the image plane side, and an aspheric surface.

Abstract: An imaging lens, although compact, has satisfactorily corrected aberrations. The imaging lens is configured by disposing, in sequence from the object side, a stop (ST); a first lens (L1), which has a double convex shape near the optical axis; a meniscus-shaped negative second lens (L2) which has near the optical axis a convex surface facing the object side; a meniscus-shaped positive third lens (L3) which has near the optical axis a concave surface facing the object side; and a positive fourth lens (L4) which has a double convex shape near the optical axis. In the configuration, the refractive power of the first lens (L1) is greater than the refractive power of each of the second lens (L2), the third lens (L3), and the fourth lens (L4).

Abstract: An imaging lens includes a first lens L1 that has a biconvex shape near an optical axis and has positive refractive power, a second lens L2 that has a biconcave shape near the optical axis and has negative refractive power, a third lens L3 that has a shape of a meniscus lens directing a concave surface thereof to an object side near an optical axis and has positive refractive power, and a fourth lens L4 that has a biconcave shape near the optical axis and has negative refractive power, arranged in this order from the object side. When the whole lens system has a focal length f and the fourth lens L4 has a focal length f4, the imaging lens of the invention satisfies the following expression: ?0.7<f4/f<?0.

Abstract: An imaging lens includes an aperture stop ST, a first lens L1 that is shaped to form a meniscus lens that directs a convex surface to the object side near an optical axis and has positive refractive power, a second lens L2 that is shaped to form a meniscus lens that directs a convex surface to the object side near the optical axis and has negative refractive power, a third lens L3 that is shaped to form a meniscus lens that directs a concave surface to the object side near the optical axis and has positive refractive power, and a fourth lens L4 that is shaped to form a meniscus lens that directs a convex surface to the object side near the optical axis, arranged in this order from an object side to an image side. When the first lens L1 has a focal length f1 and the second lens L2 has a focal length f2, the imaging lens is configured such that a relationship 0.3<|f1/f2|<0.7 is satisfied.

Abstract: An opening method for a packaging bag with a fastener enables the fastener to be surely opened with a simplified arrangement and by a simple operation as compared to the prior art. A packaging bag with a fastener is held by being gripped at the laterally opposite side edges thereof with a pair of grippers. A pair of suction cups are disposed at respective stand-by positions at both sides of the bag. The suction cups are moved to respective mutually close positions and allowed to adhere to both side surfaces of the bag at respective regions where the fastener is present. The suction cups adhering to the bag are retracted to respective intermediate positions. The movement of the suction cups between the mutually close positions and the intermediate positions is repeated a plurality of times. Thereafter, the suction cups are returned to the stand-by positions. The fastener is opened stepwise.

Abstract: A bag supplying device including a conveying arm that has a fixed clamping element and a movable clamping element, a reciprocating-rotating assembly that causes the conveying arm to make a back-and-forth rotational movement between a downwardly-facing clamping position and a substantially horizontal intermediate position, a slide frame on which the rotational shaft is rotatably supported, a reciprocating movement assembly that reciprocates the slide frame horizontally so that the conveying arm advances toward and retracts from a transfer position (where bags are transferred) to a gripper, and an opening-and-closing assembly that opens and closes the movable clamping element. With the bag mouth of an empty bag clamped by the clamping element, the conveying arm rotates upward and then advances to the transfer position, then the movable clamping element opens so as to transfer the empty bag, which is in a vertical attitude, to the gripper.

Abstract: A bag opening apparatus and method for use in a bag filling and packaging machine using flat bags allow a bag to move to a subsequent step while being surely maintained in the state of having been opened. At a mouth opening step, the mouth portion of a bag is opened by using suction cups serving as a mouth opening device. Next, an abutting member of a bag bottom deforming device is moved upward to abut on the bottom of the bag, thereby deforming at least a part of the bottom inward of the bag, while restraining movement of a lower portion of the bag with retaining plates of a bag movement restraining device.

Abstract: A bag supplying device including a conveying arm that has a fixed clamping element and a movable clamping element, a reciprocating-rotating assembly that causes the conveying arm to make a back-and-forth rotational movement between a downwardly-facing clamping position and a substantially horizontal intermediate position, a slide frame on which the rotational shaft is rotatably supported, a reciprocating movement assembly that reciprocates the slide frame horizontally so that the conveying arm advances toward and retracts from a transfer position (where bags are transferred) to a gripper, and an opening-and-closing assembly that opens and closes the movable clamping element. With the bag mouth of an empty bag clamped by the clamping element, the conveying arm rotates upward and then advances to the transfer position, then the movable clamping element opens so as to transfer the empty bag, which is in a vertical attitude, to the gripper.

Abstract: A bag opening apparatus and method for use in a bag filling and packaging machine using flat bags allow a bag to move to a subsequent step while being surely maintained in the state of having been opened. At a mouth opening step, the mouth portion of a bag is opened by using suction cups serving as a mouth opening device. Next, an abutting member of a bag bottom deforming device is moved upward to abut on the bottom of the bag, thereby deforming at least a part of the bottom inward of the bag, while restraining movement of a lower portion of the bag with retaining plates of a bag movement restraining device.