Coil unit, method of manufacturing the same, and electronic instrument
A coil unit includes a planar coil, a printed circuit board that includes a planar coil placement section that receives the planar coil, a protective sheet that is provided on a transmission side of the planar coil and protects the planar coil, and a magnetic sheet that is provided on a non-transmission side of the planar coil. The planar coil is placed in the planar coil placement section and is electrically connected to the printed circuit board. The planar coil placement section has a shape that corresponds to an external shape of the planar coil.
1. A coil unit comprising:
a planar coil having a transmission side and a non-transmission side;
a printed circuit board that includes a planar coil placement section that receives the planar coil so as to reduce a thickness of the coil unit by a thickness of the planar coil; and
a magnetic sheet that is provided on the non-transmission side of the planar coil,
the planar coil placement section being a first hole formed through the printed circuit board in a thickness direction, the hole having a shape that corresponds to an external shape of the planar coil,
the planar coil being formed by winding a coated coil wire in a plane and having an air-core section, an inner terminal, an outer terminal, a first lead line connected to the inner terminal and a second lead line connected to the outer terminal,
the first lead line being provided over the non-transmission side of the planar coil,
the printed circuit board having a lead line placement section that receives the first lead line and the second lead line, the lead line placement section being a second hole formed through the printed circuit board in the thickness direction,
the second hole of the lead line placement section being continuous with the first hole of the planar coil placement section, and
the printed circuit board having a first electrode and a second electrode on a surface that is the same side as the non-transmission side of the planar coil, the first electrode being connected to the first lead line and the second electrode being connected to the second lead line.
2. The coil unit as defined in claim 1 , further comprising a protective sheet that is provided on the transmission side of the planar coil and protects the planar coil,
the protective sheet having a first positioning hole that is formed at a position corresponding to the air-core section of the planar coil.
3. The coil unit as defined in claim 2 ,
the printed circuit board having a second positioning hole; and
the protective sheet having a third positioning hole that is formed at a position corresponding to the second positioning hole.
4. The coil unit as defined in claim 1 , further comprising a protective sheet that is provided on the transmission side of the planar coil and protects the planar coil,
the protective sheet being a heat sink sheet that has a thermal conductivity of 1 WmK or more.
5. The coil unit as defined in claim 1 ,
a mounted circuit being provided on a non-transmission side of the printed circuit board.
6. The coil unit as defined in claim 5 ,
a common ground electrode surface being formed on a transmission side of the printed circuit board, the common ground electrode surface being electrically connected to the mounted circuit.
7. An electronic instrument comprising the coil unit as defined in claim 1 .