Liquid ejection head
A liquid ejection head includes multiple ejection ports; multiple pressure chambers; a printing element substrate on which printing elements are arrayed and in which a supply flow channel that extends in a direction in which the multiple pressure chambers are arrayed and that supplies the multiple pressure chambers with a liquid and a collection flow channel that extends in the direction and that collects the liquid from the multiple pressure chambers are provided; and at least two or more bypasses as flow channels that do not pass through the pressure chambers, and in which the at least two or more bypasses include at least one of two or more bypasses for each supply flow channel and two or more bypasses for each collection flow channel.
1 . A liquid ejection head, comprising:
a printing element substrate comprising:
an ejection port row in which a plurality of ejection ports are arrayed in an arrayment direction;
a plurality of pressure chambers communicating with the plurality of ejection ports, respectively;
a plurality of printing elements provided in the plurality of pressure chambers, respectively;
a liquid supply channel extending in the arrayment direction and supplying a liquid to the plurality of pressure chambers; and
a liquid collection channel extending in the arrayment direction and collecting the liquid from the plurality of pressure chambers;
a supply communication port supplying the liquid to the printing element substrate via a supply opening;
a collection communication port collecting the liquid from the printing element substrate via a collection opening; and
at least either of two or more flow-in bypasses and two or more discharge bypasses as flow channels that do not pass through the pressure chambers, wherein
the two or more flow-in bypasses connect a plurality of flow-in bypass openings with the collection opening;
the two or more discharge bypasses connect a plurality of discharge bypass openings with the supply opening; and
each flow-in bypass opening is positioned between the supply communication port and the liquid collection channel in a positional relation along a route through which the liquid is supplied and is an opening supplying the liquid to the liquid collection channel, and each discharge bypass opening is positioned between the liquid supply channel and the collection communication port and is an opening collecting the liquid from the liquid supply channel.
2 . The liquid ejection head according to claim 1 , wherein
the supply communication port and the collection communication port are formed in a support member that supports the printing element substrate directly or indirectly.
3 . The liquid ejection head according to claim 2 , wherein
the number of supply communication ports connected to each liquid supply channel is two or more, and the number of collection communication ports connected to each liquid collection channel is two or more.
4 . The liquid ejection head according to claim 2 , wherein
the discharge bypass openings and the flow-in bypass openings are formed in a lamination direction of the printing element substrate and the support member by photolithography.
5 . The liquid ejection head according to claim 2 , wherein
a cover plate is provided between the printing element substrate and the support member, and
the supply opening and the collection are provided in the cover plate, and at least either of the plurality of discharge bypass openings and the plurality of flow-in bypass openings is formed in the cover plate.
6 . The liquid ejection head according to claim 5 , wherein
the cover plate is formed of a photosensitive resin or silicon, and
the supply opening, the collection opening, the discharge bypass openings, and the flow-in bypass openings are formed by photolithography on the cover plate.
7 . The liquid ejection head according to claim 6 , wherein
the discharge bypass openings and the flow-in bypass openings are each formed in a thickness direction of the cover plate and penetrate the cover plate.
8 . The liquid ejection head according to claim 2 , wherein
in the arrayment direction, one of the plurality of flow-in bypass openings is arranged on an end portion side of the plurality of discharge bypass openings.
9 . The liquid ejection head according to claim 5 , wherein
a pressure difference between the flow-in bypass openings and the collection openings is 70 mmAq or lower.
10 . The liquid ejection head according to claim 5 , wherein
a pressure difference between the supply opening and the discharge bypass openings is 70 mmAq or lower.
11 . The liquid ejection head according to claim 5 , wherein
a pressure difference between the flow-in bypass openings and the collection opening is 70 mmAq or lower, and
a pressure difference between the supply opening and the discharge bypass openings is 70 mmAq or lower.
12 . The liquid ejection head according to claim 2 , wherein
each of the flow-in bypasses and the discharge bypasses is a circular tube of a diameter of 0.11 mm or less or a tube having a flow resistance per pipeline length equal to that of the circular tube.
13 . The liquid ejection head according to claim 2 , wherein
each of a flow resistance per pipeline length of the flow-in bypasses and a flow resistance per pipeline length of the discharge bypasses is equal to or greater than a flow resistance per pipeline length of a circular tube of a diameter of 0.08 mm.
14 . The liquid ejection head according to claim 2 , wherein
each of a cross-section area of an opening shape of the flow-in bypass openings and a cross-section area of an opening shape of the discharge bypass openings is equal to or greater than a cross-section area of a circular tube of a diameter of 0.04 mm.
15 . The liquid ejection head according to claim 2 , wherein
a combined resistance of a path passing through the flow-in bypasses or the discharge bypasses but not passing through the pressure chambers is ⅕ or greater of a combined resistance of a path from an inlet of the liquid supply channel to an outlet of the liquid collection channel in a case of passing through the pressure chambers.
16 . The liquid ejection head according to claim 2 , wherein
each printing element is a heating element.
17 . The liquid ejection head according to claim 2 , wherein
the printing element substrate includes a temperature sensor and a heating unit, and
temperature control during printing is executed by using the temperature sensor and the heating unit.
18 . The liquid ejection head according to claim 2 , wherein
each printing element is a piezoelectric element, and
an integrated circuit that provides a waveform to the piezoelectric element and the printing element substrate are thermally connected with each other.
19 . The liquid ejection head according to claim 1 , wherein
the liquid ejection head comprises two or more of the flow-in bypasses and two or more of the discharge bypasses.