Abstract: A color luminance meter 1 is provided with a polychrometer 4 as a spectral optical system including a light receiving sensor array 43, a signal processing circuit 5 and an operation control unit 6. The operation control unit 6 carries out calculations to obtain characteristics of a measurement light based on a specified spectral responsitivity, using light reception signals and specified weighting coefficients. The spectral responsitivities of light receiving sensors constructing the light receiving sensor array 43 are selected such that B?5 nm and A/B lies within a range of 1.5 to 4.0 when A, B denote the half power band width of the spectral responsitivities and a center wavelength interval of the spectral responsitivities. Accordingly, there can be provided a light measuring apparatus capable of maximally suppressing errors to highly precisely measure color luminance values and the like even in a measurement of a light lying in a narrow band such as a monochromatic light.

Abstract: An ink jet head of an ink jet printer of a drop-on-demand type achieves mounting or connection between a driving electrode and an external electrode easily and surely and at the same time reduces revolution of a piezoelectric material during driving. Between the driving electrode with an insulating film and the external electrode is provided an electrical joining component containing electroconductive particles that are harder than the insulating film and that have a particle diameter larger than the thickness of the insulating film. At the bottom part of a slot in a piezoelectric material that forms an ink chamber and pressure chamber is provided a concave portion having a shape formed of combined at least two lines or surfaces. A part of a surface causing a revolution is converted to a component causing a shearing mode.