Surface light source device of side light type

A surface light source device of side light type, comprising:

• a guide plate having two major surfaces to provide an emission surface and a back surface, and a primary light source to supply illuminating light from an end surface of said guide plate,
• wherein at least one of said two major surfaces provides a light control surface having projections repeatedly arranged and running in a direction approximately perpendicular to said end surface, with each of said projections including a slope-couple connecting a pair of slopes with a dullness, defined as degree of roundness of the slope-couple, being given to said slope-couple in the vicinity of the end surface in a tendency to an increase in dullness in accordance with approaches to left-hand and right-hand side portions so as to produce a uniform emitting intensity from said emission surface.

A surface light source device of side light type, comprising:

• a guide plate having two major surfaces to provide an emission surface and a back surface, and a primary light source to supply illuminating light from an end surface of said guide plate,
• wherein at least one of said two major surfaces provides a light control surface having projections repeatedly arranged and running in a direction approximately perpendicular to said end surface, with each of said projections including a slope-couple connecting a pair of slopes with a dullness, defined as degree of roundness of the slope-couple, being given to said slope-couple in a tendency to an increase in dullness in accordance with an approach to the end surface from a distal end of said guide plate so as to produce a uniform emitting intensity from said emission surface.

A surface light source device of side light type, comprising:

• a guide plate having two major surfaces to provide an emission surface and a back surface, and a primary light source to supply illuminating light from an end surface of said guide plate,
• wherein at least one of said two major surfaces provides a light control surface having projections repeatedly arranged and running in a direction approximately perpendicular to said end surface, with each of said projections including a slope-couple connecting a pair of slopes with a dullness, defined as degree of roundness of the slope-couple, being given to said slope-couple in the vicinity of the end surface in a tendency to an increase in dullness in accordance with approaches to left-hand and right-hand side portions and also in another tendency to an increase in dullness in accordance with an approach to the end surface from a distal end of said guide plate so as to produce a uniform emitting intensity from said emission surface.

A surface light source device of side light type, comprising:

• a guide plate having two major surfaces to provide an emission surface and a back surface, and a primary light source to supply illuminating light from an end surface of said guide plate,
• wherein said emission surface provides a light control surface having projections repeatedly arranged and running in a direction approximately perpendicular to said end surface, with each of said projections including a slope-couple connecting a pair of slopes with a dullness, defined as degree of roundness of the slope-couple varying in accordance with position on said emission surface, being given to said slope-couple so as to produce a uniform emitting intensity from said emission surface.

A surface light source device of side light type, comprising:

• a guide plate having two major surfaces to provide an emission surface and a back surface, and a primary light source to supply illuminating light from an end surface of said guide plate,
• wherein said emission surface provides a light control surface having projections repeatedly arranged and running in a direction approximately perpendicular to said end surface, with each of said projections including a slope-couple connecting a pair of slopes with a dullness, defined as degree of roundness of the slope-couple, being given to said slope-couple in the vicinity of the end surface in a tendency to an increase in dullness in accordance with approaches to left-hand and right-hand side portions so as to produce a uniform emitting intensity from said emission surface.

A surface light source device of side light type, comprising:

• a guide plate having two major surfaces to provide an emission surface and a back surface, and a primary light source to supply illuminating light from an end surface of said guide plate,
• wherein said emission surface provides a light control surface having projections repeatedly arranged and running in a direction approximately perpendicular to said end surface, with each of said projections including a slope-couple connecting a pair of slopes with a dullness, defined as degree of roundness of the slope-couple, being given to said slope-couple in a tendency to an increase in dullness in accordance with an approach to the end surface from a distal end of said guide plate so as to produce a uniform emitting intensity from said emission surface.

A surface light source device of side light type, comprising:

• a guide plate having two major surfaces to provide an emission surface and a back surface, and a primary light source to supply illuminating light from an end surface of said guide plate,
• wherein said emission surface provides a light control surface having projections repeatedly arranged and running in a direction approximately perpendicular to said end surface, with each of said projections including a slope-couple connecting a pair of slopes with a dullness, defined as degree of roundness of the slope-couple, being given to said slope-couple in the vicinity of the end surface in a tendency to an increase in dullness in accordance with approaches to left-hand and right-hand side portions and also in another tendency to an increase in dullness in accordance with an approach to the end surface from a distal end of said guide plate so as to produce a uniform emitting intensity from said emission surface.

A surface light source device of side light type, comprising:

• a guide plate having two major surfaces to provide an emission surface and a back surface, and a primary light source to supply illuminating light from an end surface of said guide plate,
• wherein said back surface provides a light control surface having projections repeatedly arranged and running in a direction approximately perpendicular to said end surface, with each of said projections including a slope-couple connecting a pair of slopes with a dullness, defined as degree of roundness of the slope-couple varying in accordance with position on said emission surface, being given to said slope-couple so as to produce a uniform emitting intensity from said emission surface.

A surface light source device of side light type, comprising:

• a guide plate having two major surfaces to provide an emission surface and a back surface, and a primary light source to supply illuminating light from an end surface of said guide plate,
• wherein said back surface provides a light control surface having projections repeatedly arranged and running in a direction approximately perpendicular to said end surface, with each of said projections including a slope-couple connecting a pair of slopes with a dullness, defined as degree of roundness of the slope-couple, being given to said slope-couple in the vicinity of the end surface in a tendency to an increase in dullness in accordance with approaches to left-hand and right-hand side portions so as to produce a uniform emitting intensity from said emission surface.

A surface light source device of side light type, comprising:

• a guide plate having two major surfaces to provide an emission surface and a back surface, and a primary light source to supply illuminating light from an end surface of said guide plate,
• wherein said back surface provides a light control surface having projections repeatedly arranged and running in a direction approximately perpendicular to said end surface, with each of said projections including a slope-couple connecting a pair of slopes with a dullness, defined as degree of roundness of the slope-couple, being given to said slope-couple in a tendency to an increase in dullness in accordance with an approach to the end surface from a distal end of said guide plate so as to produce a uniform emitting intensity from said emission surface.

A surface light source device of side light type, comprising:

• a guide plate having two major surfaces to provide an emission surface and a back surface, and a primary light source to supply illuminating light from an end surface of said guide plate,
• wherein said back surface provides a light control surface having projections repeatedly arranged and running in a direction approximately perpendicular to said end surface, with each of said projections including a slope-couple connecting a pair of slopes with a dullness, defined as degree of roundness of the slope-couple, being given to said lope-couple in the vicinity of the end surface in a tendency to an increase in dullness in accordance with approaches to left-hand and right-hand side portions and also in another tendency to an increase in dullness in accordance with an approach to said incidence surface from a distal end of said guide plate so as to produce a uniform emitting intensity from said emission surface.