Abstract: An imaging lens includes a first lens group and a second lens group, arranged in this order from an object side to an image plane side. The first lens group includes a first lens, a second lens, and a third lens having negative refractive power. The second lens group includes a fourth lens, a fifth lens having negative refractive power, and a sixth lens having negative refractive power. The fourth lens has a specific Abbe's number. The fifth lens has a specific Abbe's number.

Abstract: An imaging lens includes a first lens group and a second lens group, arranged in this order from an object side to an image plane side. The first lens group includes a first lens, a second lens, and a third lens. The second lens group includes a front side lens group and a rear side lens group. The front side lens group includes a fourth lens and a fifth lens. The rear side lens group includes a sixth lens having two aspheric surfaces and a seventh lens having two aspheric surfaces. The imaging lens has a total of seven single lenses. The first to seventh lenses are arranged respectively with a space in between. The third and fourth lenses have convex surfaces on the image plane side. The fifth lens has a convex surface on the object side. The rear side lens group has a specific focal length.

Abstract: An imaging lens includes a first lens group and a second lens group, arranged in this order from an object side to an image plane side. The first lens group includes a first lens, a second lens, and a third lens having negative refractive power. The second lens group includes a fourth lens, a fifth lens having negative refractive power, and a sixth lens. The third lens has a concave surface facing the image plane side near an optical axis thereof. The fourth lens has a specific Abbe's number. The fifth lens has a specific Abbe's number.

Abstract: An imaging lens includes a first lens group having positive refractive power and a second lens group having negative refractive power, arranged in this order from an object side to an image plane side. The first lens group includes a first lens, a second lens, and a third lens. The second lens group includes a fourth lens, a fifth lens having negative refractive power, and a sixth lens. The third lens has a concave surface facing the image plane side near an optical axis thereof. The sixth lens has a concave surface facing the object side near an optical axis thereof. The fifth lens has a specific Abbe's number.

Abstract: An imaging lens includes a first lens; a second lens; a third lens; a fourth lens; a fifth lens; a sixth lens; and a seventh lens, arranged in this order from an object side to an image plane side. The imaging lens has a total of seven lenses. The first to seventh lenses are arranged respectively with a space in between. The second lens is formed in a meniscus shape near an optical axis. The third lens is formed in a meniscus shape so that a surface on the object side is convex near an optical axis. The sixth lens is formed in a meniscus shape near an optical axis. The seventh lens is formed in a shape so that a surface on the image plane side has at least one inflexion point. The first lens and the second lens have specific Abbe's numbers.

Abstract: An imaging lens includes a first lens group; and a second lens group, arranged from an object side to an image plane side. The first lens group includes a first lens having negative refractive power and a second lens. The second lens group includes a third lens having positive refractive power and a fourth lens having negative refractive power. The fourth lens is formed in a shape so that a curvature radius of a surface thereof on the image plane side is positive. The first lens, the second lens and the third lens have specific Abbe's numbers, the first lens is arranged to be away from the second lens, the second lens is arranged to be away from the third lens, and the third lens is arranged to be away from the fourth lens by specific distances on an optical axis so that the specific conditional expressions are satisfied.

Abstract: An imaging lens includes a first lens; a second lens; a third lens; a fourth lens; a fifth lens; a sixth lens; and a seventh lens, arranged in this order from an object side to an image plane side. The imaging lens has a total of seven lenses. The first to seventh lenses are arranged respectively with a space in between. The first lens is formed in a shape so that a surface thereof on the object side is convex near an optical axis. The fifth lens is formed in a shape so that a surface thereof on the image plane side is concave near an optical axis. The seventh lens is formed in a shape so that a surface thereof on the image plane side has at least one inflexion point and is concave near an optical axis.

Abstract: In a noise reduction device that generates and outputs a control sound signal for reducing noise, an internal loop control unit controls an internal loop in which a pre-output control sound signal that is acquired from a control sound output unit before output to a speaker is input to a sound receiver. A measurement unit measures an input level of a microphone sound signal and an input level of the pre-output control sound signal that has been input to the sound receiver in the internal loop. A fault detector uses the input level of the microphone sound signal and the input level of the pre-output control sound signal measured by the measurement unit to detect a fault in any one of the microphone, the sound receiver, the speaker, and the control sound output unit. A transmitter sends a result of fault detection performed by the fault detector to a management device.

Abstract: An imaging lens includes a first lens having positive refractive power; a second lens; a third lens; a fourth lens; a fifth lens having positive refractive power; and a sixth lens having negative refractive power, arranged in this order from an object side to an image plane side. The first lens is formed in a shape so that surfaces on the object side and the image plane side are convex near an optical axis. The second lens is formed in a meniscus shape near an optical axis. The fifth lens is formed in a shape so that surfaces on the object side and the image plane side are convex near an optical axis. The sixth lens is formed in a shape so that surfaces on the object side and the image plane side are concave near an optical axis. The first lens has a specific Abbe's number.

Abstract: With the noise reduction device (300), in identifying an acoustic transfer function that includes a path from the control speaker (340) to the error microphone (350) or the noise microphone (320) by outputting an identification sound from the control speaker (340) and detecting the identification sound with the error microphone (350) or the noise microphone (320), the identification controller (338) is configured to identify the acoustic transfer function by generating the identification sound from the white noise generator (337) when the seat detector (582) has detected that the seat is in the actual usage state for noise reduction.

Abstract: An imaging lens includes a stop; a first lens; a second lens; a third lens having positive refractive power; a fourth lens; a fifth lens having positive refractive power; and a sixth lens, arranged in this order from an object side to an image plane side. The fourth lens is formed in a shape so that a surface thereof on the image plane side is convex near an optical axis thereof. The sixth lens is formed in a shape so that a surface thereof on the image plane side is concave near an optical axis thereof. The second lens is formed in a shape so that a surface thereof on the object side and a surface thereof on the image plane side have specific curvature radii.

Abstract: An imaging lens includes a first lens group and a second lens group, arranged in this order from an object side to an image plane side. The first lens group includes a first lens, a second lens, and a third lens. The second lens group includes a fourth lens, a fifth lens having positive refractive power, a sixth lens having two aspheric surfaces, and a seventh lens having two aspheric surfaces. The imaging lens has a total of seven single lenses. The first to seventh lenses are arranged respectively with a space in between. The third lens is formed in a shape so that a surface on the object side is convex. The fourth lens is formed in a shape so that a surface on the object side is concave. The fifth lens is formed in a shape so that a surface on the image plane side is concave.

Abstract: An imaging lens includes a first lens group and a second lens group, arranged from an object side to an image plane side. The first lens group includes a first lens, a second lens, and a third lens. The second lens group includes a front side lens group and a rear side lens group. The front side lens group includes a fourth lens and a fifth lens. The rear side lens group includes a sixth lens and a seventh lens both having two aspheric surfaces. The imaging lens has a total of seven single lenses. The first to seventh lenses are arranged respectively with a space in between. The third lens has convex surfaces on both sides. The fourth lens has a concave surface on the object side. The fifth lens has a concave surface on the image plane side. The rear side lens group has a specific focal length.

Abstract: An imaging lens includes a first lens having positive refractive power; a second lens having negative refractive power; a third lens having positive refractive power; a fourth lens having positive refractive power; a fifth lens; and a sixth lens having negative refractive power, arranged in this order from an object side to an image plane side. The second lens is formed in a shape so that surfaces on the both sides have positive curvature radii. The sixth lens is formed in a shape so that surfaces on the both sides have negative curvature radii. The fourth lens is arranged to be away from the fifth lens by a specific distance on an optical axis, and the imaging lens has a specific angle of view so that specific conditional expressions are satisfied.

Abstract: An imaging lens includes a first lens group and a second lens group, arranged in this order from an object side to an image plane side. The first lens group includes a first lens having negative refractive power, a second lens having negative refractive power, and a third lens. The second lens group includes a fourth lens and a fifth lens having negative refractive power. The first lens is formed in a shape so that a curvature radius of a surface thereof on the image plane side is positive. The fifth lens is formed in a shape so that a surface thereof on the image plane side is aspheric.

Abstract: An imaging lens includes a first lens having one aspheric surface and positive refractive power; a second lens having one aspheric surface and negative refractive power; a third lens having one aspheric surface; a fourth lens having one aspheric surface; a fifth lens having one aspheric surface; a sixth lens having two aspheric surfaces; and a seventh lens having two aspheric surfaces, arranged in this order from an object side to an image plane side respectively with a space in between. The imaging lens has a total of seven lenses. The first lens is formed in a meniscus shape so that a surface on the object side is convex near an optical axis. The sixth lens is formed in a shape so that a surface on the image plane side is concave near an optical axis. The fifth lens has a specific Abbe's number.

Abstract: An imaging lens includes a first lens; a second lens; a third lens; a fourth lens; a fifth lens; a sixth lens; and a seventh lens, arranged in this order from an object side to an image plane side. The imaging lens has a total of seven lenses. The first to seventh lenses are arranged respectively with a space in between. The first lens is formed in a shape so that a surface on the object side is convex near an optical axis. The second lens is formed in a shape so that a surface on the image plane side is concave near an optical axis. The fifth lens is formed in a shape so that a surface on the image plane side is concave near an optical axis. The seventh lens is formed in a shape so that a surface on the image plane side has one inflexion point.

Abstract: An imaging lens includes a first lens having at least one aspheric surface and positive refractive power; a second lens having at least one aspheric surface; a third lens having at least one aspheric surface; a fourth lens having at least one aspheric surface; a fifth lens having at least one aspheric surface; a sixth lens having two aspheric surfaces; and a seventh lens having two aspheric surfaces and negative refractive power, arranged in this order from an object side to an image plane side respectively with a space in between. The imaging lens has a total of seven lenses. The fourth lens and the sixth lens have specific Abbe's numbers.

Abstract: An imaging lens includes a first lens having at least one aspheric surface and positive refractive power; a second lens having at least one aspheric surface and negative refractive power; a third lens having at least one aspheric surface; a fourth lens having at least one aspheric surface; a fifth lens having at least one aspheric surface; a sixth lens having two aspheric surfaces; and a seventh lens having two aspheric surfaces, arranged in this order from an object side to an image plane side respectively with a space in between. The imaging lens has a total of seven lenses. The fifth lens is disposed away from the sixth lens by a specific distance on an optical axis.

Abstract: In the noise reduction device, the sound receiver receives a noise signal acquired from the microphone. The sound source input unit receives an input of a sound source signal from a sound source. The sound adjuster changes the intensity of the sound source signal relative to the intensity of the noise signal. The control sound generator generates a control sound signal that reduces the noise signal. The control unit controls the change of the intensity of the sound source signal and the generation of the control sound signal. The sound output outputs the control sound signal to the speaker. The sound output outputs to the speaker the sound source signal at the intensity changed by the sound adjuster.