liquid storing opening 302 in a preferred embodiment the liquid storing wall 32 has an arc shaped surface the width of the first liquid storing opening 302 is greater than the width d 1 of the second liquid storing opening 304 preferably the width d 1 of the second liquid storing opening 304 ranges from 3 to 45 u03bcm owing to that the liquid storing wall 32 has an arc shaped surface and that the width of the first liquid storing opening 302 is greater than the width d 1 of the second liquid storing opening 304 the liquid in a container can easily enter the liquid storing space 30 via the wider first liquid storing opening 302 and then the arc shaped surface of the liquid storing wall 32 smoothly guides the liquid to go out from the narrower second liquid storing opening 304 such a structure favors liquid atomization or tiny droplet formation fig3 is a sectional view schematically showing a liquid guiding space 40 of an orifice 20 a according to one embodiment of the present invention as shown in fig1 the liquid guiding space 40 connects and communicates with the liquid storing space 30 and the liquid outputting space 50 so as to guide liquid to flow from the liquid storing space 30 to the liquid outputting space 50 the liquid guiding space 40 is defined by a liquid guiding wall 42 of the plate 10 and has a width d 2 the liquid guiding space 40 connects and communicates with the liquid storing space 30 via the.