Vehicle signal lamp

A vehicle signal lamp comprising:

• a boundary;
• a first lamp unit including a first casing having a first opening, a first outer lens having a first inner portion, and a first lamp room, the first outer lens attached to the first casing and covering the first opening of the first casing, and thereby the first lamp room formed between the first casing and the first outer lens, and the first inner portion of the first outer lens extending in a direction toward the first casing from the first outer lens along the boundary;
• at least one first light source having a first light-emitting direction located in the first lamp room, and the first light-emitting direction of the first light source being directed toward the first outer lens of the first lamp unit;
• a second lamp unit including a second casing having a second opening, a second outer lens having a second inner portion, and a second lamp room, the second outer lens attached to the second casing and covering the second opening of the second casing, and thereby the second lamp room formed between the second casing and the second outer lens, and the second inner portion of the second outer lens extending in a direction toward the second casing from the second outer lens along the boundary, and therefore facing the first inner portion of the first outer lens via the boundary, which is located between the first lamp unit and the second lamp unit, the second inner portion of the second outer lens including a second inner end surface, a second outer surface and a second inner surface located in an opposite direction of the second outer surface, and substantially facing the boundary, the second inner surface of the second inner portion including a plurality of concavo-convex surfaces, which extends in a substantially horizontal direction of the vehicle signal lamp;
• a boundary light source having a boundary light-emitting direction facing the second inner end surface of the second outer lens, and the boundary light-emitting direction of the boundary light source being directed toward the second inner end surface of the second outer lens;
• and
• at least one second light source having a second light-emitting direction located in the second lamp room, and the second light-emitting direction of the second light source being directed toward the second outer lens of the second lamp unit.