Abstract: In the disclosed diaphragm device, an electromagnetic unit is composed of two opposing sets of circularly arranged magnets poled so that opposing surfaces have the same polarity, a rotary member carrying an electromagnetic coil that moves the rotary member in response to current therethrough and the field of the magnets, and diaphragm blades which are positioned between the magnet members and the rotary member and pivoted to close the aperture in response to rotation of the rotary member in one direction. When the rotary member is rotating in the closing direction, stopping means respond to an input signal and stop movement of the diaphragm blades at a particular aperture value.

Abstract: The carburetor of a motorcycle engine is fastened to an engine cylinder by a thin resilient hose connecting the fuel mixture outlet port of the carburetor to the intake port of the cylinder. The carburetor is fastened to the casing of the associated air cleaner much more rigidly than it is fastened to the cylinder. The fastening connection between the carburetor and the air cleaner casing is provided by a tubular member having a wider orifice fastened to said casing, a narrower orifice fastened to the carburetor, and a shoulder portion connecting the orifices and of greater wall thickness near the float chamber in the carburetor than elsewhere.

Abstract: Three-layer anti-reflection coatings consisting of first, second and third layers, respectively positioned from a glass base plate. The optical film thickness of the first layer and the second layer is one-half of a designed wavelength while that of the third layer is one-fourth of the same. And the relationship among the refractive index of each layer is second layer (n.sub.2) glass (n.sub.g) first layer (n.sub.1) third layer (n.sub.3). The first layer is made of a mixture of Al.sub.2 O.sub.3 and ZrO.sub.2.