Plastic bonding method

A method of making integral members for a planar light source device, the method comprising:

• irradiating one of opposite surfaces of a first member made of a plastic material, that is to be bonded with a second member, with energy rays having quantum energy not lower than 4 eV;
• and
• directly bonding the first and second members together at room temperature after the irradiating without any bonding agent being used,
• wherein respective mating surfaces of the first and the second members are not melted when bonding,
• wherein:
• the second member comprises a light guide element for propagating rays of light from a light source towards a light exit surface thereof;
• and
• the first member comprises an optical film disposed on the light exit surface of the light guide element;
• and forming a plurality of projections operable to transmit rays of light from the light exit surface of the light guide element towards a front surface region of the light exit surface, on one of opposite surfaces of the optical film that confronts the light guide element;
• wherein the light guide element is directly bonded with the optical film at vertexes of the plural projections.

A method of making integral members for a planar light source device, the method comprising:

• irradiating one of opposite surfaces of a first member made of a plastic material, that is to be bonded with a second member, with energy rays having quantum energy not lower than 4 eV;
• and
• directly bonding the first and second members together at room temperature after the irradiating without any bonding agent being used,
• wherein respective mating surfaces of the first and the second members are not melted when bonding, and
• wherein one of opposite surfaces of the second member that is to be bonded with the first member is irradiated with the energy rays having quantum energy not lower than 4 eV;
• wherein:
• the first member comprises a light guide element for propagating rays of light from a light source towards a light exit surface thereof;
• and
• the second member comprises an optical film disposed on the light exit surface of the light guide element;
• and forming a plurality of projections operable to transmit rays of light from the light exit surface of the light guide element towards a front surface region of the light exit surface, on one of opposite surfaces of the optical film that confronts the light guide element;
• wherein the light guide element is directly bonded with the optical film at vertexes of the plural projections.