Abstract: In a thermal type flow rate measurement apparatus comprising a sub-passage having a detour passage and a hole just before a flow rate measuring part, for preventing its output value from falling onto a negative side when the flow rate is abruptly changed, a slit is formed downstream of a flow rate detecting element located after the detour passage. The slit hole may be arranged between the flow rate detecting element and the outlet port part, and may be opened between a wall surface side and a recess part. Thereby, it is possible to prevent the output value from falling in the negative side upon rise-up thereof.

Abstract: An optical quantizing unit includes an optical divider dividing 1st optical pulses to be quantized and sending the divided 1st optical pulses into a plurality of paths; a plurality of optical filters passing with different transmittances the divided 1st optical pulses; and an optical threshold filter sequentially receiving the 1st optical pulses, and sending 2nd optical pulses when light intensities of the 1st optical pulses are above a preset threshold value.

Abstract: To realize a control apparatus for an internal combustion engine having a heating resistor type air flow rate measuring apparatus which can effectively remove salinity adhered to the heating resistor. Salt adheres not only to the heating portion of a heating resistor but also to lead members and supporting members. When a certain time period is passed after the current supply to the heating resistor is stopped, the salt adhered thereto absorbs moisture in the air by deliquescence, and becomes salt water near the heating resistor and the support members etc. Then, suction air flows through an auxiliary air passage by the cranking of the engine to disperse the salt water adhered not only to the support member parts but also to the heating resistor. Thus, even if the heating resistor is supplied with current after the dissipation, salt components do not remain on the heating resistor.

Abstract: In a Fresnel lens which is made of a lens material whose refraction index is n, and focuses light beam from a light source at a specified radiation view angle ?, and has plural N pieces of circular lens surfaces arranged concentrically around a common optical axis, and plural circular rise surfaces arranged adjacent alternately between these lens surfaces, and two lens surfaces adjacent via at least one of the rise surfaces are concave surfaces, and tangent lines and at the intersecting point with the rise surfaces of the shape of a cross section passing through the optical axis of those lens surfaces intersect at the outside with respect to the optical axis, and when the angle formed between these tangent lines is defined as ?, a relational equation ???/(2 n N) stands.