Liquid ejection head, liquid ejection apparatus, and method of supplying liquid

1. A liquid ejection head comprising:

an ejection opening for ejecting a liquid;

a pressure chamber having therein an energy generation element for generating energy for ejecting the liquid;

an ejection opening portion that allows communication between the ejection opening and the pressure chamber;

a first flow passage connected to the pressure chamber and supplying the liquid to the pressure chamber; and

a second flow passage connected to the pressure chamber and collecting the liquid from the pressure chamber,

wherein an expression of H −0.34 ×P −0.66 ×W>1.7 is satisfied when a height of the pressure chamber on the first flow passage side is set to H [μm],

a length of the ejection opening portion in a direction in which the liquid is ejected from the ejection opening is set to P [μm], and

a length of the ejection opening portion in a flow direction of the liquid inside the pressure chamber is set to W [μm].

2. The liquid ejection head according to claim 1 , further comprising:

an orifice plate on which the ejection opening and the ejection opening portion are formed; and

a substrate on which the energy generating element is formed,

wherein between the orifice plate and the substrate, the pressure chamber, the first flow passage, and the second flow passage are formed.

3. The liquid ejection head according to claim 1 ,

wherein the height H is 20 [μm] or less, the length P is 20 [μm] or less, and the length W is 30 [μm] or less.

4. The liquid ejection head according to claim 1 ,

further comprising a plurality of the energy generating elements and a plurality of the pressure chambers,

wherein partition walls are provided between the plurality of energy generating elements, and the pressure chambers are regions between the plurality of partition walls.

5. The liquid ejection head according to claim 1 ,

wherein the liquid inside the pressure chamber is circulated between the pressure chamber and the outside.

6. The liquid ejection head according to claim 1 ,

wherein the ejection opening is provided with two protrusions extending toward a center portion of the ejection opening.

7. The liquid ejection head according to claim 6 , wherein the two protrusions extend in a direction intersecting with a direction from a connection portion between the first flow passage and the pressure chamber to a connection portion between the second flow passage and the pressure chamber.

8. The liquid ejection head according to claim 7 ,

wherein the liquid ejection head is a page-wide liquid ejection head having a length corresponding to a width of a printing medium, and

wherein the liquid ejection head further comprises:

a plurality of printing element substrates each including an orifice plate having the ejection opening and the ejection opening portion, and a substrate having the energy generating element, and

a flow passage member extending along a longitudinal direction of the liquid ejection head.

9. The liquid ejection head according to claim 8 ,

wherein each of the plurality of printing element substrates is provided with a flexible circuit board.

10. The liquid ejection head according to claim 9 , wherein flexible wiring substrates provided on each of the printing element substrates extend along one another.

11. The liquid ejection head according to claim 8 , wherein a cover member having an opening for exposing the ejection opening is provided on the side where the plurality of printing element substrates are provided.

12. The liquid ejection head according to claim 8 , further comprising a support member for supporting at least one of the printing element substrates and an ejection module including the printing element substrate and the support member.

13. The liquid ejection head according to claim 12 , wherein a plurality of the ejection modules are arranged along the longitudinal direction of the liquid ejection head.

14. The liquid ejection head according to claim 1 , wherein an input terminal for inputting a signal from the outside to the liquid ejection head is provided on a side surface portion along a longitudinal direction of the liquid ejection head.

15. The liquid ejection head according to claim 1 , wherein the energy generation element is an electro-thermal conversion element.

16. The liquid ejection head according to claim 1 , wherein the first flow passage and the second flow passage are arranged on a straight line in the direction in which liquid is ejected from the ejection opening.

17. The liquid ejection head according to claim 1 , wherein an opening area of the ejection opening is smaller than an opening area of a communication portion between the ejection opening portion and the pressure chamber.

18. The liquid ejection head according to claim 1 ,

wherein a viscosity of the liquid flowing in the pressure chamber is 30 cP or less.

19. The liquid ejection head according to claim 1 ,

wherein a velocity of the liquid flowing in the pressure chamber is in a range of 0.1 to 100 mm/s.

20. A liquid ejection apparatus having a liquid ejection head,

the liquid ejection head comprising:

an ejection opening for ejecting a liquid;

a pressure chamber having therein an energy generation element for generating energy for ejecting the liquid;

an ejection opening portion that allows communication between the ejection opening and the pressure chamber;

a first flow passage connected to the pressure chamber and supplying the liquid to the pressure chamber; and

a second flow passage connected to the pressure chamber and collecting the liquid from the pressure chamber,

wherein an expression of H −0.34 ×P −0.66 ×W>1.7 is satisfied when a height of the pressure chamber on the first flow passage side is set to H [μm],

a length of the ejection opening portion in a direction in which the liquid is ejected from the ejection opening is set to P [μm], and

a length of the ejection opening portion in a flow direction of the liquid inside the pressure chamber is set to W [μm].