| 摘要 |
PROBLEM TO BE SOLVED: To improve the representation of a gradation, especially on a low concentration side by metering a medium to be metered with the help of a heating element when the medium to be metered is mixed with a discharge medium and the mixture is jetted. SOLUTION: A heat-generating element 11 which consists of a resistor 25 with both ends to which electrodes 23a, 23b are connected, on a heat accumulation layer 21 and a protecting coating 24 formed on the resistor 25 and generates heat through energization to the resistor 25, is installed in a second pressure chamber 9 filled with a metered medium in such a manner that the protecting coating 24 comes into contact with the metered medium in the pressure chamber 9. The heat-generating element 11 has an in-plane temperature distribution on the surface of the element at the time of heat generation. In this heating element 11, the temperature distribution should preferably be formed in the in-plane direction at the time of heat generation by changing the heat generating value of the resistor 25, at its energization, in the in-plane direction. In addition, the thickness of the protecting coating 24 is changed in the in-plane direction of the heating element 11. Alternatively, the thickness of the heat accumulation layer 21 may be changed in the in-plane direction of the heating element 11, so that the in-plane temperature distribution at the time of heat generation is formed. |
