Light emitting device and diffusion member used therein

A light-emitting device comprising:

• a substrate;
• a wiring formed in the substrate;
• a light-emitting element including an electrode electrically connected to the wiring, and configured to emit light having a main wavelength in a range from 420 nm to 560 nm, and
• a diffusion member disposed on a light-emitting surface side of the light-emitting element on a side opposite to a surface on which the electrode is formed, wherein
• a first direction parallel to one side of the diffusion member and a second direction orthogonal to the first direction are defined when the diffusion member is viewed in plan view,
• a first measurement plane is defined as a plane passing through a center of an outer shape of the diffusion member when viewed in plan view, parallel to the first direction, and perpendicular to a light emission surface of the diffusion member, and
• a second measurement plane is defined as a plane passing through the center of the outer shape, parallel to the second direction, and perpendicular to the light emission surface of the diffusion member,
• when chromaticity x and chromaticity y of an emission color of the light-emitting device are measured in each of the first measurement plane and the second measurement plane in a prescribed range in which an angle at the center of the outer shape is in a range from -60° to 60° with reference to a perpendicular line passing through the center of the outer shape, being orthogonal to the light emission surface, and extending in a light emission observation direction,
• an average value β of a difference between a maximum value and a minimum value of a chromaticity difference Δy of the chromaticity y measured in the first measurement plane and a difference between a maximum value and a minimum value of a chromaticity difference Δy of the chromaticity y measured in the second measurement plane is less than 30% of an average value β′ obtained by measuring an emission color of a light-emitting device including a transparent member instead of the diffusion member.

A light-emitting device comprising:

• a substrate;
• a wiring formed in the substrate;
• a light-emitting element including an electrode electrically connected to the wiring, and configured to emit light having a main wavelength in a range from 420 nm to 560 nm, and
• a diffusion member disposed on a light-emitting surface side of the light-emitting element on a side opposite to a surface on which the electrode is formed, wherein
• a first direction parallel to one side of the diffusion member and a second direction orthogonal to the first direction are defined when the diffusion member is viewed in plan view,
• a first measurement plane is defined as a plane passing through a center of an outer shape of the diffusion member when viewed in plan view, parallel to the first direction, and perpendicular to a light emission surface of the diffusion member, and
• a second measurement plane is defined as a plane passing through the center of the outer shape, parallel to the second direction, and perpendicular to the light emission surface of the diffusion member,
• when chromaticity x and chromaticity y of an emission color of the light-emitting device are measured in each of the first measurement plane and the second measurement plane in a range in which an angle at the center of the outer shape is in a range from -60° to 60° with reference to a perpendicular line passing through the center of the outer shape, being orthogonal to the light emission surface, and extending in a light emission observation direction,
• an average value β of a difference between a maximum value and a minimum value of a chromaticity difference Δy of the chromaticity y measured in the first measurement plane and a difference between a maximum value and a minimum value of a chromaticity difference Δy of the chromaticity y measured in the second measurement plane satisfies formula (1) below,
• β
• <0
• .0006y
• 0
• + 0
• .0006
• in formula (1) above, y0 is the chromaticity y of the emission color of the light-emitting device measured on the perpendicular line passing through the center of the outer shape, being orthogonal to the light emission surface, and extending in a light emission observation direction.

A light-emitting device comprising:

• a substrate;
• a wiring formed in the substrate;
• a light-emitting element including an electrode electrically connected to the wiring, and configured to emit light having a main wavelength in a range from 420 nm to 480 nm;
• and
• a diffusion member disposed on a light-emitting surface side of the light-emitting element on a side opposite to a surface on which the electrode is formed, wherein
• a first direction parallel to one side of the diffusion member and a second direction orthogonal to the first direction are defined when the diffusion member is viewed in plan view,
• a first measurement plane is defined as a plane passing through a center of an outer shape of the diffusion member when viewed in plan view, parallel to the first direction, and perpendicular to a light emission surface of the diffusion member, and
• a second measurement plane is defined as a plane passing through the center of the outer shape, parallel to the second direction, and perpendicular to the light emission surface of the diffusion member,
• when chromaticity x and chromaticity y of an emission color of the light-emitting device are measured in each of the first measurement plane and the second measurement plane in a range in which an angle at the center of the outer shape is in a range from -60° to 60° with reference to a perpendicular line passing through the center of the outer shape, being orthogonal to the light emission surface, and extending in a light emission observation direction,
• an average value β of a difference between a maximum value and a minimum value of a chromaticity difference Δy of the chromaticity y measured in the first measurement plane and a difference between a maximum value and a minimum value of a chromaticity difference Δy of the chromaticity y measured on the second measurement plane is less than 0.0006.

A diffusion member configured to diffuse light from a light-emitting element configured to emit light having a main wavelength of 523 nm, the diffusion member comprising:

• a surface configured to face a light-emitting surface of the light-emitting element when the diffusion member is disposed on the light-emitting element to allow light from the light-emitting element to pass through the diffusion member;
• and
• one side parallel to a first direction when the diffusion member is viewed in plan view, wherein
• a first measurement plane is defined as a plane passing through a center of an outer shape of the diffusion member when viewed in plan view, parallel to the first direction, and perpendicular to a light emission surface of the diffusion member, and
• a second measurement plane is defined as a plane passing through the center of the outer shape, being parallel to a second direction orthogonal to the first direction, and perpendicular to the light emission surface of the diffusion member,
• when chromaticity x and chromaticity y of an emission color of the light passing through the diffusion member are measured in each of the first measurement plane and the second measurement plane in a range in which an angle at the center of the outer shape is in a range from -60° to 60° with reference to a perpendicular line passing through the center of the outer shape, being orthogonal to the light emission surface, and extending in a light emission observation direction,
• an average value β of a difference between a maximum value and a minimum value of a chromaticity difference Δy of the chromaticity y measured in the first measurement plane and a difference between a maximum value and a minimum value of a chromaticity difference Δy of the chromaticity y measured in the second measurement plane is less than 30% of an average value β′ obtained by measuring the emission color of the light from light-emitting element, the light passing through a transparent member disposed on the light-emitting surface of the light-emitting element instead of the diffusion member.