close

Вход

Забыли?

вход по аккаунту

?

JPH0213003

код для вставкиСкачать
Patent Translate
Powered by EPO and Google
Notice
This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
financial decisions, should not be based on machine-translation output.
DESCRIPTION JPH0213003
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
temperature compensation circuit used in an amplifier circuit for driving a negative impedance,
and in particular, it is used to rationally realize temperature compensation of a drive state. 2.
Description of the Related Art Generally, a speaker has a voice coil disposed in a magnetic gap of
a magnetic circuit, and a diaphragm or the like is driven by passing a driving current through the
voice coil. Here, the voice coil has a unique internal impedance including a DC resistance
component, which is the Q value of the resonance of the sound pressure reproduction
characteristic of the speaker system in which the speaker is disposed, and the lowest resonance
frequency f. Have an important impact. The applicant filed a patent application for an acoustic
reproduction apparatus in which the DC resistance component of the voice coil was equivalently
invalidated or reduced, paying attention to such a fact (Japanese Patent Application No. 62334262.334263, etc.) Unpublished). The equivalent circuit diagram which expressed this
notionally is shown in FIG. 5 (a). In the same figure, CM and LH are the capacitance and
inductance of the motional impedance ZM of the electromagnetic converter (speaker),
respectively, and Rv is the internal resistance of the voice coil which is a load. This internal
resistance Rv is reduced by the negative resistance -RA formed equivalently on the drive side,
and the apparent drive impedance ZA is 2 "" Rv-Rt. となる。 However, when ZA becomes
negative, the operation of the circuit becomes unstable, so RvRARA. According to this sound
reproducing apparatus, the Q value of the resonance of the unit vibration system consisting of
speakers is ideally zero and the lowest resonance frequency f. Also disappears. Furthermore,
when the above-mentioned resonator is driven, strong resonance acoustic radiation can be
realized because the Q value of resonance is not lowered. In order to perform such negative
impedance driving, it is necessary to equivalently generate a negative impedance, and for that
purpose, as a current detecting element 3 in series with a speaker that is a load 2, a detecting
08-05-2019
1
cord R Is connected. FIG. 5 (b) shows a circuit diagram of the negative impedance generating
circuit. As shown, detection resistance R is S connected to load 2 (internal resistance R), and the
detection output is applied to adder 5 via feedback circuit 4 with feedback factor β, and positive
for amplifier 1 with amplification factor A. I will return. Therefore, the equivalent output
impedance R8 for the load 2 is Ro-R8 (1-A-.beta.). [Problems to be Solved by the Invention]
However, in this negative impedance drive, it is usually the case that appropriate temperature
compensation is not applied to the change in direct current resistance Rv of the voice coil due to
the temperature change of the voice coil of the speaker. In the case of the constant voltage drive
of the above, the fluctuation of the driving state is caused larger than in the case of the constant
voltage driving.
And considering that the voice coil is made of copper wire etc., the temperature rise can not be
avoided. However, a device for actively compensating for such a temperature change of the
internal resistance R is not particularly made conventionally. Therefore, an object of the present
invention is to provide a temperature compensation circuit capable of performing temperature
compensation of a load with a simple configuration. [Means for Solving the Problems] In the
temperature compensation circuit according to the present invention, the detection output of the
current detection means inserted in series in the speaker serving as a load is positively fed back
to the input terminal to make negative resistance in the output impedance. In the speaker driving
amplifier circuit which produces the component and equivalently reduces or cancels the direct
current resistance of the voice coil of the speaker, the current detecting means is a heat radiation
which raises the temperature almost equal to the voice coil material of the speaker A
temperature sensing means of a predetermined resistance temperature coefficient thermally
coupled to the current detecting means is provided, and a feedback of positive feedback is made
by an electrical change corresponding to the temperature of the temperature sensing means. It is
characterized by controlling the quantity. Here, instead of the temperature sensing means
described above, temperature detection means thermally coupled to the current detection means
may be provided, and multiplication means for multiplying the detection signal of the
temperature detection means by the feedback rate of positive feedback may be provided. Good.
[Operation] According to the configuration of the present invention, since the drive current
flowing through the voice coil of the speaker flows directly to the current detection element, the
current detection element exhibits substantially the same temperature rise as the temperature of
the voice coil rises. It will be. Here, the current detecting element and the temperature sensing
means or the temperature detecting means are thermally coupled, whereby the positive feedback
is controlled. Therefore, the above-mentioned temperature compensation is performed.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention will be
described in detail with reference to FIGS. 1 to 4 of the accompanying drawings. In the
description of the drawings, the same elements will be denoted by the same reference symbols,
without redundant description. FIG. 1 is a circuit diagram of a negative impedance drive circuit
according to a first embodiment. 5 is different from the circuit of FIG. 5 (b) in that a temperature
08-05-2019
2
sensitive resistance element (for example, a thermistor) R thermally coupled to the detection
resistance R as the current detection means 3 is provided, and this is connected to the feedback
circuit 4 It is that you are. Here, the heat radiation resistance and the thermal time constant of
the detection resistor R in FIG. 1 are set such that the temperature rise of the voice coil of the
speaker 2 and the temperature rise of the detection resistor R become between paths. According
to the first embodiment, since the feedback ratio β of the feedback circuit 4 is controlled
according to the temperature rise of the detection resistor R6, temperature compensation can be
suitably performed.
This will be explained by the specific example of FIG. Here, a temperature coefficient of the same
polarity as the voice coil R of the speaker 2 as the detection resistance R (when the voice coil R
has a positive temperature coefficient such as vv copper, the detection resistance R also has a
positive temperature coefficient) ) Is shown. In this case, the drive impedance of the equivalent
motional impedance ZH is R + R + 1 + A (1 + R / R1) 1 v S x (1) because the feedback ratio β is
β−1 + R / R1. Here, since it is only the voice coil R and the temperature sensitive resistance R
that has a temperature coefficient, if this is extracted by v x (1), R-RA (R / R 1) (2) v S x
Therefore, if this is zero, temperature compensation is ideally performed, and R = RA (R / R1) vSx.
Here, for the voice coil R1 temperature-sensitive resistor R, R-R (1 + K-T) v vo Tv v R-R (1 + K-T)
X XOT x x (where R is the value of R at 0 ° C, vOvK Temperature coefficient of R, Tv v Tv:
temperature of R, R value of R at 0 ° C., xO x K: temperature coefficient of R, Tx x T, temperature
of R (2) becomes R (1 + K-T) voTvv-RA-R (1 + K-T) / R1sxoTxX. Here, since TV: = fT is set by the
above-described thermal coupling, (1 + K 1 −T 2) / (1 + K −T 2) Tv v Tx x? By using the
temperature-sensitive resistor Rx that nails the temperature coefficient KTx such that (R−A−R) /
(R−R) s x o t, it is possible to almost eliminate the influence of temperature. When a temperature
sensitive resistor R having a temperature coefficient reverse to that of the voice coil R is used, X
may have a circuit configuration as shown in FIG. Next, a second embodiment of the present
invention will be described with reference to FIG. FIG. 4 is a circuit diagram thereof. Here, a
temperature detection element 11 thermally coupled to the detection resistor R is provided, and
this detection signal (change parameter due to temperature) is given to the conversion circuit 12
and converted into a voltage signal (Y).
Then, this voltage signal (Y) is given to the multiplier 13, multiplied by the feedback signal (X)
from the feedback circuit 4, and given to the adder 5. In this circuit, the drive impedance of the
equivalent motional impedance ZH is R + R (1−AβY) (3) v S. Here, assuming that the voice coil
resistance R at 0 ° C. is R, v v O (1 + K −T) R (4) T v V VO can be obtained. Therefore, the
equation (3) is (1 + K-T) RTv v v. + R (1−AβY) (5) Here, since it is Ktv and Y that have
temperature parameters in equation (5), RvOKTVTV-RSAβY-0 is sufficient, and RvoKTvTv -Rs
AβY (6), and equation (6) is T-(R,. K, v) / RSAβ (7) Here, since T ′ x T is set by the abovedescribed thermal coupling, temperature / voltage conversion characteristics Y / T R (RvOKlx) /
08-05-2019
3
(RsAβ) from the temperature S degree of the detection resistor R to the voltage signal (Y) It is
sufficient to set the temperature detection element 11 and the conversion circuit 12 so that In
the second embodiment, various temperature detection elements 11 can be used. For example, a
resistor having a temperature coefficient, a thermistor, a semiconductor such as a posistor, a
thermocouple, or the like can be used. Alternatively, a junction voltage of an element such as a
transistor or a diode may be used. Further, the multiplier 13 may be a multiplier circuit (vCA)
configured by VBE (base-emitter voltage) characteristics of a transistor or a circuit using a
resistance change region such as an FET, a lamp such as an LED and Cd It may be a circuit
combining an S cell or an analog switch circuit. [Effects of the Invention] As described above, in
the present invention, since the drive current flowing through the voice coil of the speaker flows
directly to the current detection element, the current detection element is substantially
equivalent as the temperature of the voice coil rises. It indicates a temperature rise, and the
current detection element and the temperature sensing means or temperature detection means
are thermally coupled. Accordingly, the temperature of the voice coil and the temperature
sensing means or the temperature detecting means likewise rise, and thereby the positive
feedback is controlled, so that the above-mentioned temperature compensation can be
performed.
[0002]
Brief description of the drawings
[0003]
FIG. 1 is a circuit diagram of a first embodiment of the present invention, and FIGS. 2 and 3 are
diagrams showing the configuration of a specific example of the circuit of FIG. 1, and FIG. 4 is a
second embodiment of the present invention. FIG. 5 is a circuit diagram of an embodiment of the
present invention, and FIG. 5 is an equivalent circuit diagram of the electrodynamic
electroacoustic transducer of the prior application and a circuit diagram of a negative impedance
generation circuit.
DESCRIPTION OF SYMBOLS 1 ... amplifier (amplification factor A) 2 ... load (speaker), 3 ... current
detection means (detection resistance R), 4 ... feedback circuit (feedback rate β), 5 ... adder , R ...
temperature sensitive resistance.
08-05-2019
4
Документ
Категория
Без категории
Просмотров
0
Размер файла
13 Кб
Теги
jph0213003
1/--страниц
Пожаловаться на содержимое документа