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Description 1, title of the invention
MFB circuit
3, Detailed Description of the Invention The present invention detects the recommendation of the
diaphragm of the speaker and converts it into a brilliance signal, and this electrical signal is the
speaker? With regard to MFB (MotlonalFeedBaak) lOJ'ilr that is fed back to the input circuit of
the gravity amplifier to be driven, a detector that detects the movement of the diaphragm can be
realized with a very electric +4 configuration, and accurate detection can be performed. It is like
this. Conventionally, there has been known an MFB circuit in which the driving of a speaker is
controlled by using a feedback circuit tl-as shown in the first paragraph. That is, the electric
signal applied to the input terminal 1 in FIG. 1 is supplied to the power increaser 11g via the
comparator 2, where it is ffi-widthed and then printed on the speaker 4 0 and The vibration of
the diaphragm of the speaker 4 is detected by the nosepiece 6, converted into an electricity 1g,
converted into an X, and then fed back to the comparator 2 via the feedback circuit 6. In the
comparator 2, the human power signal and the 4 far signal are compared, and the difference is
supplied to the power increaser 3. Heretofore, the detection section of this MFB circuit has been
constructed as shown in FIG. In Fig. lX2, 7I voice coil bobbin, S is a voice coil bobbin 7Vc one
hundredth-mounted convex @@ 5-bobbin, 91f, T, movable 'It pole attached to this bobbin 8, 1o a
center ball, 11 Is an insulator fixed on the center ball 10, 12 is a position facing the town ah 79
above the insulator 11, v is mounted VC, j is a stationary plate, 13 is a diaphragm o like this If
configured, the Boy EndPage: 1 coil bobbin 7 is driven in the lateral direction in the drawing
according to the input signal, and the diaphragm 13 is perturbed accordingly. Then, in
accordance with the drive of the + 'chair coil bobbing 7, the opposing area of the movable
electrode 9 and the fixed power and jli 12 is unified, so that the capacitance formed between
these two (9 and 12 changes. This change in capacitance may be proportional to the
displacement of the swing plate 13 [) or may be detected and fed back to the input circuit of the
force amplifier. However, in this case, it may be adhered to the movable electrode bobbin 81kM s
coil Gevin 7, or the bonding of the bonded part of the sheep becomes incomplete and the
recommendation of the voice coil bobbin 7 is not transmitted to the movable electrode 711.
There is a neck. In addition, since the phase shift at high frequencies also becomes large, there
was an open end that sufficient MFB could not be applied. The present invention is intended to
provide an MFB circuit that solves such problems. Hereinafter, an embodiment of the present
invention will be described with reference to FIG.
FIG. 3 shows the structure of the detection unit which is an essential part of the present
invention. In FIG. 3, reference numeral 14 denotes a voice coil bobbin made of aluminum foil, 15
voice coils wound around a bobbin 14, 16 a yoke, 17 center pole, 18 an insulator fixed on the
center pole 17 19 is a metal foil attached to a position on the insulator 18 opposite to the voice
coil bobbin 14, 2o is a diaphragm, and 21 is a damper. In the above configuration, the voice coil
bobbin 14 acts as a movable electrode and as the evening, and is on the ground side of each of
the electrostatic charges t. And metal foil 19 works as a fixed electrode. That is, when the voice
coil bobbin 14 is driven to the left and right in the figure according to the input signal, the facing
area of the voice coil bobbin 14 and the metal foil 19 changes, and the capacitance formed
between them changes. Therefore, the change in capacitance may be detected. As described
above, according to the present invention, since the voice coil bobbin of the speaker is formed of
metal foil and used as an eT moving electrode, the following excellent effects can be obtained. (A)
It is possible to accurately detect the change in each of the electrostatics according to the
movement of the voice coil bobbin. Since it is almost directly connected to the O (b) voice coil,
the speaker input 2>-etc. up to the detector output There is little phase rotation, and deep MFBff
can be applied in a wide band according to the system. (C) The processing for the speaker can be
reduced compared to the conventional one, and the processing can be performed very easily.
Particularly in recent years, a speaker in which the voice coil bobbin is made of aluminum foil is
used to enhance the heat radiation effect of the voice coil bobbin. However, when the present
invention is applied to such a speaker, it is extremely inexpensive and easy. It can be realized.
Because the voice coil bobbin is on the ground side of the capacitance, induction by high voltage
of the voice coil is also avoided. (E) Because it is efficient, it can be applied to squawkers and
4. Brief Description of the Drawings FIG. 1 is a circuit diagram for explaining the principle of an
FMB circuit, FIG. 2 is a cross-sectional view showing the main part of a conventional MFB circuit,
and FIG. 3 shows the main part of the present invention. FIG. DESCRIPTION OF SYMBOLS 1: .....
input terminal, 2 ...... comparator, 3 ... squid heater @ 4 ..... speaker, 6 ... detector .. 6 ... · · ·
Feedback circuit, 14 · · · · · · voice coil bobbin (movable 1. Poles, 16 ······ Voice coil, 16 ··· Yoke, 17
··· Center pole, 18 ······································ Metal foil (fixed? [Pole], 2 o ..... Vibrating plate. Name of
agent Attorney Nakakishi, man and one other EndPage: 2