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US-12617203-B2 - Liquid discharge head, element substrate and method for manufacturing the same

US12617203B2US 12617203 B2US12617203 B2US 12617203B2US-12617203-B2

Abstract

A liquid discharge head includes first, second and third substrates. The second substrate includes a piezoelectric element configured to generate energy for discharging liquid, and a protective layer. The protective layer includes a first protective layer in contact with the piezoelectric element and a second protective layer covering the first protective layer, wherein L 3 >L 1 >L 2 is satisfied, where L 1 is a length of a through hole, L 2 is a length of a communication port connecting the through hole and a liquid chamber in the second substrate, and L 3 is a length of an opening of the protective layer, on a straight line passing through a center of the through hole when viewed from a direction perpendicular to a surface of the element substrate, and wherein an inner wall surface of the opening of the protective layer is a substantially flat surface.

Inventors

  • Masataka Kato

Assignees

  • CANON KABUSHIKI KAISHA

Dates

Publication Date
20260505
Application Date
20240208
Priority Date
20230213

Claims (13)

  1. 1 . A liquid discharge head comprising an element substrate, the element substrate including: a first substrate including a discharge opening for discharging a liquid; a second substrate joined with the first substrate and including a liquid chamber for supplying the liquid to the discharge opening; and a third substrate joined with the second substrate via an adhesive and including a through hole for supplying the liquid to the liquid chamber, wherein the second substrate includes: a piezoelectric element disposed on a surface closer to the third substrate, the piezoelectric element being configured to generate energy for discharging the liquid; and a protective layer covering at least part of the piezoelectric element and including an opening connecting the liquid chamber and the through hole, wherein the protective layer includes a first protective layer in contact with the piezoelectric element and a second protective layer covering the first protective layer, wherein L 3 >L 1 >L 2 is satisfied, where L 1 is a length of the through hole, L 2 is a length of a communication port connecting the through hole and the liquid chamber in the second substrate, and L 3 is a length of the opening of the protective layer, on a straight line passing through a center of the through hole when viewed from a direction perpendicular to a surface of the element substrate, wherein an inner wall surface of the opening of the protective layer is a substantially flat surface, and wherein the inner wall surface of the opening of the protective layer is in contact with the adhesive.
  2. 2 . The liquid discharge head according to claim 1 , wherein in the opening of the protective layer, an inner wall surface of an opening in the first protective layer and an inner wall surface of an opening in the second protective layer are aligned when viewed from the direction perpendicular to the surface of the element substrate.
  3. 3 . A liquid discharge head comprising an element substrate, the element substrate including: a first substrate including a discharge opening for discharging a liquid; a second substrate joined with the first substrate and including a liquid chamber for supplying the liquid to the discharge opening; and a third substrate joined with the second substrate via an adhesive and including a through hole for supplying the liquid to the liquid chamber, wherein the second substrate includes: a piezoelectric element disposed on a surface closer to the third substrate, the piezoelectric element being configured to generate energy for discharging the liquid; and a protective layer covering at least part of the piezoelectric element and including an opening connecting the liquid chamber and the through hole, wherein the protective layer includes a first protective layer in contact with the piezoelectric element and a second protective layer covering the first protective layer, wherein L 3 >L 1 >L 2 is satisfied, where L 1 is a length of the through hole, L 2 is a length of a communication port connecting the through hole and the liquid chamber in the second substrate, and L 3 is a length of the opening of the protective layer, on a straight line passing through a center of the through hole when viewed from a direction perpendicular to a surface of the element substrate, wherein an inner wall surface of the opening of the protective layer is a substantially flat surface, and wherein in the opening of the protective layer, an edge of the first protective layer is covered by the second protective layer.
  4. 4 . The liquid discharge head according to claim 1 , wherein L 2 >L 1 ×0.6 is satisfied, where L 1 is an opening diameter of the through hole and L 2 is an opening diameter of the communication port connecting the through hole and the liquid chamber in the second substrate, when viewed from the direction perpendicular to the surface of the element substrate.
  5. 5 . The liquid discharge head according to claim 1 , wherein L 2 >L 1 ×0.75 is satisfied, where L 1 is an opening diameter of the through hole and L 2 is an opening diameter of the communication port connecting the through hole and the liquid chamber in the second substrate, when viewed from the direction perpendicular to the surface of the element substrate.
  6. 6 . The liquid discharge head according to claim 1 , wherein the first protective layer is silicon oxide, and the second protective layer is silicon nitride.
  7. 7 . The liquid discharge head according to claim 1 , wherein a distance from a periphery of the through hole to a periphery of the protective layer is greater than or equal to 5 μm, when viewed from the direction perpendicular to the surface of the element substrate.
  8. 8 . The liquid discharge head according to claim 1 , wherein the third substrate further includes a second through hole for collecting the liquid from the liquid chamber, and wherein the liquid is allowed to circulate between the liquid chamber and outside.
  9. 9 . The liquid discharge head according to claim 1 , wherein a surface in the element substrate that is to be in contact with the liquid is covered by a corrosion-resistant film.
  10. 10 . The liquid discharge head according to claim 9 , wherein the corrosion-resistant film includes tantalum oxide.
  11. 11 . The liquid discharge head according to claim 1 , wherein both of the second substrate and the third substrate are silicon substrates.
  12. 12 . The liquid discharge head according to claim 1 , wherein at least one of the first protective layer or the second protective layer includes an opening on a surface of the piezoelectric element that is on an opposite side to a side closer to the vibration plate.
  13. 13 . An element substrate for use in a liquid discharge head, the element substrate comprising: a first substrate including a discharge opening for discharging a liquid; a second substrate joined with the first substrate and including a liquid chamber for supplying the liquid to the discharge opening; and a third substrate joined with the second substrate via an adhesive and including a through hole for supplying the liquid to the liquid chamber, wherein the second substrate includes: a piezoelectric element on a surface closer to the third substrate, the piezoelectric element being configured to generate energy for discharging the liquid; and a protective layer covering at least part of the piezoelectric element and including an opening connecting the liquid chamber and the through hole, wherein the protective layer includes a first protective layer in contact with the piezoelectric element and a second protective layer covering the first protective layer, wherein L 3 >L 1 >L 2 is satisfied, where L 1 is a length of the through hole, L 2 is a length of a communication port connecting the through hole and the liquid chamber in the second substrate, and L 3 is a length of the opening of the protective layer, on a straight line passing through a center of the through hole when viewed from a direction perpendicular to a surface of the element substrate, wherein an inner wall surface of the opening of the protective layer is a substantially flat surface, and wherein the inner wall surface of the opening of the protective layer is in contact with the adhesive.

Description

BACKGROUND Field of the Disclosure The present disclosure relates to a liquid discharge head, an element substrate, and a method for manufacturing the same. Description of the Related Art A mechanism that uses piezoelectric elements for discharging liquid in a liquid discharge head of a liquid discharge apparatus, such as an inkjet recording apparatus, is known. In the mechanism, part of a liquid chamber storing the liquid is formed using a vibration plate, and a voltage is applied to the piezoelectric elements to deform the vibration plate and contract the liquid chamber so that the liquid is discharged through a discharge opening formed at one end of the liquid chamber. There are liquid discharge heads that include an element substrate including a discharge opening substrate, an actuator substrate, and a flow path substrate joined together in this order. A discharge opening is formed in the discharge opening substrate. The actuator substrate includes a vibration plate and a piezoelectric film, and a liquid chamber is formed in the actuator substrate. The flow path substrate includes a flow path for supplying liquid to the liquid chamber. Japanese Patent Application Laid-Open No. 2015-100919 discusses a liquid discharge head that includes the above-described element substrate. A wiring layer for feeding electric signals to piezoelectric elements is situated on a side of the actuator substrate that is in contact with the flow path substrate, and an insulative layer and a protective layer are layered to cover the wiring layer. FIGS. 2A and 2B are cross-sectional views illustrating an element substrate according to a comparative example of the present disclosure. In FIGS. 2A and 2B, an actuator substrate 20 and a flow path substrate 10 are joined together with an adhesive 40, and there is a step shape formed at a joint surface by end portions of an insulative layer 241 and a protective layer 242 near a through hole 100 formed in the flow path substrate 10. In this case, the adhesive 40 on edges of the insulative layer 241 and the protective layer 242 sometimes peels and forms a particle 41. SUMMARY The present disclosure is directed to providing a liquid discharge head and an element substrate for a liquid discharge head with high discharge stability and in which formation of particles originating from an adhesive is reduced. According to an aspect of the present disclosure, a liquid discharge head includes an element substrate including a first substrate including a discharge opening for discharging a liquid, a second substrate joined with the first substrate and including a liquid chamber for supplying the liquid to the discharge opening, and a third substrate joined with the second substrate via an adhesive and including a through hole for supplying the liquid to the liquid chamber, wherein the second substrate includes a piezoelectric element disposed on a surface closer to the third substrate, the piezoelectric element being configured to generate energy for discharging the liquid, and a protective layer covering at least part of the piezoelectric element and including an opening connecting the liquid chamber and the through hole, wherein the protective layer includes a first protective layer in contact with the piezoelectric element and a second protective layer covering the first protective layer, wherein L3>L1>L2 is satisfied, where L1 is a length of the through hole, L2 is a length of a communication port connecting the through hole and the liquid chamber in the second substrate, and L3 is a length of the opening of the protective layer, on a straight line passing through a center of the through hole when viewed from a direction perpendicular to a surface of the element substrate, and wherein an inner wall surface of the opening of the protective layer is a substantially flat surface. According to another aspect of the present disclosure, a method for manufacturing an element substrate for use in a liquid discharge head, the element substrate including a first substrate including a discharge opening for discharging a liquid, a second substrate joined with the first substrate and including a liquid chamber for supplying the liquid to the discharge opening, and a third substrate joined with the second substrate via an adhesive and including a through hole for supplying the liquid to the liquid chamber, includes forming, on a side of the second substrate that is in contact with the third substrate, a piezoelectric element configured to generate energy for discharging the liquid, forming a protective layer f covering the piezoelectric element and including a first protective layer in contact with the piezoelectric element and a second protective layer covering the first protective layer, and forming an opening in the protective layer to connect the liquid chamber and the through hole by etching the first protective layer and the second protective layer simultaneously, wherein L3>L1>L2 is satisfied, where