| abstract |
Disclosed is a bulb-shaped lamp that simultaneously achieves improved heat dissipation and reduced size and weight, and reduces the thermal load on the lighting circuit. A bulb-shaped lamp (1) comprises an LED module (3) which has an LED, a cylindrical case (7) which is equipped with a base member (15) at one end and dissipates heat during LED light emission, a mounting member (5) at which the LED module (3) is mounted and which closes the other end of the case (7) and transfers the aforementioned heat to the case (7), a lighting circuit (11) which receives power supplied via the base member (15) and causes the LED to emit light, and a circuit holder (13) which is disposed inside the case (7) and houses the lighting circuit (11). There is an air layer between the circuit holder (13), and the case (7) and the mounting member (5), the lighting circuit (11) is isolated from the aforementioned air layer by the circuit holder (13), and the contact surface area ratio S1/S2, where S1 is the contact surface area between the mounting member (5) and the case (7) and S2 is the contact surface area between the substrate (17) of the LED module (3) and the mounting member (5), meets the condition that S1/S2 is not less than 0.5. |