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BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
speaker capable of accurately detecting a temperature line of a voice coil unit. Generally, the
voice coil of the speaker is wound with a copper wire or an aluminum wire. When an audio
current flows through this voice coil, Joule heat is generated due to the electrical resistance of
these conductors. When a large current flows in the voice coil, heat is generated in proportion to
the resistance component, burning of the adhesive for fixing the voice coil bobbin and the voice
coil and melting of the coil lead occur, and the function of the speaker unit is lost. Generally,
voice coil bobbins are paper bobbins made of kraft paper etc. In particular, in order to withstand
large input, thermosetting resin bobbins such as polyimide film, metal foil bobbins such as
aluminum foil are used, and heat resistance is improved. But was inadequate. Conventionally, as
shown in FIG. 1, the thermal relay 1 using a bimetal is incorporated in the speaker system to
prevent the above-mentioned thermal deterioration, and the bimetal part is thermally deformed
when a large current flows in it. The contact point is opened to disconnect between the speaker
system and the amplifier, thereby preventing destruction of the voice coil portion of the speaker
2 due to heat generation. However, this method of protecting the speaker unit by the thermal
relay does not detect the actual temperature rise of the voice coil portion, but uses the
correlation between the amount of current flowing through the speaker and the temperature rise
of the voice coil portion. Furthermore, the temperature rise of the voice coil portion and the
temperature of the bimetal portion are not necessarily due to the variation of the temperature
characteristics of the bimetal portion of the thermal relay 1 and the difference in ambient
temperature, or the difference between the heat transfer coefficient of the voice coil portion and
the heat transfer coefficient of the bimetal portion. There was a drawback that the rise did not
correspond. SUMMARY OF THE INVENTION Therefore, the present invention is to provide a
speaker which directly detects the temperature of the voice fill section by utilizing the property
that the resistance of the metal conductor generally increases as the temperature rises. .
(Structure of the Invention) In order to achieve the above object, a seven rekin pull printed circuit
board having a metal conductor circuit formed thereon is used as a bobbin and a voice coil is
wound around it. Assuming that the resistance value of the metal conductor circuit at t2 ░ C.
and t2 ░ C. is R, (?), R2 (?), R2 = R, (] + ?, (12-1,)). иии (1) where ?1 is the temperature rise of
the voice coil section if the resistance values R1 and R2 of the metal conductor circuit are
measured from the temperature coefficient of resistance (2) of the metal conductor at t1 ░ C. I
can know.
Hereinafter, the embodiment will be described in detail with reference to the drawings.
(Description of the Embodiment) FIG. 2 shows an embodiment of the present invention, and
shows a flexible printed circuit board 5 which is a bobbin for winding a voice coil. 6 denotes a
conductor circuit formed by etching a copper foil on a flexible substrate by a known
photoetching method, and 7 and 8 denote lead terminals. An insulating layer and a pheno for
bonding voice coil are coated on the printed circuit board 5 and formed into a cylindrical shape,
which is used as a bobbin. FIG. 3 shows a voice coil in which a voice coil 9 is wound around the
bobbin and the temperature detection conductor circuit 6 is provided. In the present
embodiment configured as described above, since the resistance value of the conductor circuit
formed on the bobbin changes in response to the temperature change of the voice coil portion,
the voice coil portion is measured by measuring this resistance value. Temperature can be
accurately detected. (Effects of the Invention) As described above, according to the present
invention, since the temperature of the voice coil portion can be accurately detected, it is possible
to prevent thermal destruction of the speaker unit in advance, and Since the temperature
detection conductor circuit is formed by the photoetching method, the manufacturing process is
simple, and moreover, the variation in resistance value can be kept small. Furthermore, if a
polyimide-based or epoxy-based thermosetting resin, or a material obtained by adding glass cloth
or the like to these is used as the base of the flexible substrate, it has heat resistance, and hence
can be used in a wide temperature range.
Brief description of the drawings
FIG. 1 is a circuit diagram of a conventional example in which a thermal relay is incorporated in a
speaker system, FIG. 2 is a view showing a flexible printed circuit board according to an
embodiment of the present invention, and FIG. 3 is a sectional view of the voice coil. is there.
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jps5972899, description
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