Circuit board structure
A circuit board structure capable of heating a battery without requiring cost for adoption and replacement of the battery is provided. In the mounting of an auxiliary battery incorporated in an in-vehicle emergency notification device as a standby power supply for a main battery and a heater resistor for heating the auxiliary battery, a heat transfer mechanism for transferring heat generated by the heater resistor to the auxiliary battery is provided on a printed board. Further, the auxiliary battery is detachably fixed on the printed board through the heat transfer mechanism.
1. A circuit board structure comprising:
a circuit board;
a battery that is detachably fixed on the circuit board;
a heating element that is disposed on the circuit board, and generates heat when a current flows to the heating element from a power supply; and
a heat transfer member that is disposed adjacent to the heating element, and transfers the heat generated by the heating element to the battery, wherein
the battery is detachably fixed on the circuit board through the heat transfer member,
the circuit board has a cutout,
the heat transfer member has:
a metallic battery holder that includes a fixing portion defining an end fixed to the circuit board, and a battery holding portion extending from the fixing portion toward the cutout and having a shape for holding the battery in the cutout; and
a heat transfer material that has an elasticity and a sheet shape, and is interposed between the circuit board and the fixing portion of the battery holder and between the battery holding portion of the battery holder and the battery.
2. The circuit board structure according to claim 1 , wherein
the heating element is disposed on one surface of the circuit board,
the heat transfer member is disposed on another surface of the circuit board, and
the circuit board is formed with a through hole at a position corresponding to a portion where the heating element is disposed and a portion where the heat transfer member is disposed, and the heat is conducted from the heating element to the heat transfer member through the through hole.
3. The circuit board structure according to claim 1 , wherein
the heating element includes a chip resistor.
4. The circuit board structure according to claim 1 , wherein
the battery has a cylindrical shape, and
the heating element is disposed along a longitudinal direction of a contour of the battery.
5. The circuit board structure according to claim 4 , wherein
a plurality of the heating elements are disposed on both sides of the battery along the longitudinal direction of the contour of the battery.
6. The circuit board structure according to claim 1 , further comprising
a temperature detection unit that detects a temperature of the battery,
wherein the temperature detection unit is disposed close to the heat transfer member on the circuit board.
7. The circuit board structure according to claim 1 , wherein
the cutout is recessed from an end of the circuit board,
the end of the fixing portion is fixed along a rim of the circuit board, the rim defining the cutout.
8. The circuit board structure according to claim 1 , wherein
the fixing portion is disposed along a surface of the circuit board through the heat transfer material, and
the battery holding portion extending from the fixing portion has a curved plate shape along a contour of the battery.
9. The circuit board structure according to claim 8 , wherein
a plurality of the heating elements is disposed along a rim of the circuit board defining the cutout, on another surface of the circuit board, the another surface being opposite to the surface along which the fixing portion is disposed through the heat transfer material, and
the circuit board is formed with a plurality of through holes at positions corresponding to the heating elements, and the heat is conducted from the heating element to the heat transfer member through the through holes.