JP2016119623

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 JP2016119623
Abstract: PROBLEM TO BE SOLVED: To provide a compact, light-weight and stable operation of a
condenser speaker and a driving method thereof. SOLUTION: A high voltage is generated by
performing light irradiation of an LED on a plurality of photodiodes connected in series, and a
voltage generated from the photodiode is also an acoustic signal by changing a light amount of
the LED according to an acoustic signal. Change according to. The output voltage of the
photodiode is applied to the fixed electrode of the capacitor speaker, and the movable electrode
is vibrated mechanically to cause acoustic output, and the voltage detected by the bleeder
resistor connected in parallel to the photodiode is compared with the acoustic signal. , Control
the LED. [Selected figure] Figure 1
Condenser speaker and method of driving the same
[0001]
The present invention relates to a condenser speaker and a method of driving the same.
[0002]
A capacitor speaker is an electrostatic type speaker which generates an acoustic wave (air
vibration) by vibrating the electrode by the coulomb force of the charge generated between the
electrodes by applying a high voltage and an acoustic signal in parallel between the parallel plate
electrodes. It is known as a kind of
[0003]
04-05-2019
1
The circuit configuration of a conventional condenser speaker is shown in FIG.
The movable electrode 52 is held at its both ends by the cushioning insulating damper 54, and
these are held by the first and second fixed electrodes 51, 53, and DC by the DC power supply 55
via the step-up transformer 56. A bias voltage is applied.
That is, positive charges are charged to the first and second fixed electrodes 51 and 53, and
negative charges are charged to the movable electrode 52. M10 to which one end of the DC
power supply 55 is connected represents the position of the secondary side center tap of the
step-up transformer 56.
[0004]
Here, when the acoustic signal source 57 is applied to the primary side of the step-up
transformer 56, the acoustic signal is applied to the first and second fixed electrodes 51 and 53
which are secondary sides of the step-up transformer 56.
[0005]
FIG. 12 shows the relationship between the voltages of the movable electrode 52 and the first
and second fixed electrodes 51 and 53, V A10, V X10, and V Y10, using the potential of M10 as
a reference potential.
A voltage of opposite phase is applied to the first and second fixed electrodes 51 and 53, and an
appropriate oscillating electric field is applied to the movable electrode 52. That is, due to the
change of the electric field strength due to the acoustic signal applied to the primary side of the
step-up transformer 56, the movable electrode 52 having a negative charge generates a
mechanical vibration according to the electric field strength by the coulomb force. The electrode
52 vibrates to generate a sound wave.
[0006]
Here, the voltage applied to the DC power supply 55 is usually several hundred volts to 1 kV, and
a Cockcroft-Waltron type booster circuit in which capacitors and diodes are connected in
multiple stages or a piezoelectric element (PLZT element) using a ferroelectric is used. The
04-05-2019
2
booster circuit used is proposed (patent documents 1-2).
[0007]
As another configuration of the capacitor speaker, there is also known a configuration in which a
high voltage power source is not required by using a pre-charged electret material as a movable
electrode or a fixed electrode (Patent Document 3).
JP-A-9-182190 JP-A-2011-30047 JP-A-2008-312109
[0008]
In the case of the conventional capacitor speaker, since a DC high voltage and an acoustic signal
which is an AC signal are superimposed and applied to the step-up transformer, a large step-up
transformer having a high insulation property is required. Therefore, not only the overall size of
the device is increased, but also it is necessary to provide a current limiting function to ensure
safety, which complicates the circuit configuration. Furthermore, a typical Cockcroft-Waltron
circuit as a booster circuit requires an expensive high breakdown voltage capacitor component,
which is not preferable in terms of operating temperature and operating life. Furthermore, there
is also a problem that high frequency noise is easily generated.
[0009]
Conventional high voltage generation circuits that do not use a step-up transformer contribute to
miniaturization, but their temperature characteristics tend to be unstable, and their volume
decreases when the DC bias voltage is small, which causes problems when applied to condenser
speakers. there were.
[0010]
The present invention has been made in view of the circumstances as described above. A step-up
transformer is not necessary and the circuit configuration is simple. Furthermore, even if it is a
high voltage, only a current of the level of everyday static electricity flows. Technical challenge is
to provide a condenser speaker that can be
04-05-2019
3
[0011]
A capacitor speaker according to the present invention includes a movable electrode and a first
fixed electrode disposed opposite to the movable electrode, and a plurality of the plurality of
serially connected movable electrodes and the first fixed electrode. A first photodiode array
comprising photodiodes, and a first bleeder resistor comprising two division resistors connected
in series is connected in parallel to the first photodiode array; A first LED control unit to which a
detection voltage divided by the dividing resistor from a voltage generated from the photodiode
array and an acoustic signal voltage obtained by adding a DC bias voltage are input, and the first
LED control unit An output from the light emitting diode is connected to a first light emitting
diode, and the first photodiode array is disposed in the vicinity of a light irradiation surface of the
first light emitting diode. The features.
[0012]
With such a configuration, it is possible to inexpensively provide a condenser speaker that
realizes a compact, lightweight, and highly temperature stable operation while preventing an
electric shock to the human body.
[0013]
Further, in the capacitor speaker according to the present invention, the first fixed electrode, the
second fixed electrode disposed to face the first fixed electrode, and the first and second fixed
electrodes are provided. And a movable electrode facing the first and second fixed electrodes, the
movable electrode and the first fixed electrode comprising a plurality of photodiodes connected
in series. A photodiode row is connected, a second photodiode row consisting of a plurality of
photodiodes connected in series is connected to the movable electrode and the second fixed
electrode, and the first photodiode row is connected to the movable electrode and the second
fixed electrode. , And a second bleeder resistor comprising two split resistors connected in series
is connected in parallel, and the second photodiode row has a second bleeder resistor having the
same resistance value as the first bleeder resistor A second LED control unit in which resistors
are connected in parallel, and a detection voltage divided by the dividing resistor from the
voltage generated from the first photodiode row and an acoustic signal voltage obtained by
adding a DC bias voltage are input The first output from the second LED control unit is connected
to the first light emitting diode, and the second output in which the first output and the acoustic
signal component are in antiphase are the second light emission. The first photodiode array is
connected to a diode, the first photodiode array is disposed in the vicinity of the light irradiation
surface of the first light emitting diode, and the second photodiode array is irradiated with light
of the second light emitting diode. It is characterized in that it is arranged near the surface.
[0014]
04-05-2019
4
With such a configuration, it is possible to provide a push-pull type capacitor speaker in which
the movable electrode vibrates by the first fixed electrode and the second fixed electrode, and it
is possible to improve the speaker characteristics in the low frequency range.
[0015]
Further, according to another embodiment of the above-described capacitor speaker according to
the present invention, the first or second LED control unit is configured by a combination of an
operational amplifier and an LED driver, or a combination of an operational amplifier and a
power MOSFET. There is.
[0016]
As a result, the light emission intensity (light intensity) of the light emitting diode (LED) can be
controlled in accordance with the acoustic signal, and by using the power MOSFET, a lower
priced capacitor speaker can be provided.
[0017]
In the condenser speaker according to the present invention, a condenser capacity formed
between the first movable electrode and the first fixed electrode, and a first bleeder connected in
parallel to the first photodiode row It is characterized in that the reciprocal of the time constant
determined by the product of the resistance and the resistance value is equal to or higher than
the drive frequency of the condenser speaker.
[0018]
With such a configuration, it is possible to output a sound up to a desired frequency range from
the condenser speaker, and it is possible to have a function as a low pass filter when PWM
modulating an acoustic signal.
[0019]
The capacitor speaker according to the present invention is characterized in that at least the first
LED control unit, the first light emitting diode, and the first photodiode row are mounted in the
same package.
[0020]
Such a configuration makes it possible to realize further reduction in size and weight and to
obtain more stable temperature characteristics.
04-05-2019
5
[0021]
In the condenser speaker according to the present invention, at least the second LED control unit,
the first light emitting diode, the first photodiode row, the second light emitting diode, and the
second photodiode row are included. It is characterized in that it is implemented in the same
package.
[0022]
With such a configuration, even in the push-pull type condenser speaker, it is possible to realize
further reduction in size and weight, and further stable temperature characteristics can be
obtained.
[0023]
The capacitor speaker according to the present invention is characterized in that the first light
emitting diode and the first photodiode row are formed on a nitride semiconductor grown on the
front and back surfaces of a sapphire substrate.
[0024]
With such a configuration, light emission and light reception can be performed at the same
wavelength, the efficiency of photoelectric conversion can be increased, and more stable
characteristics can be obtained.
[0025]
In the capacitor speaker according to the present invention, the first light emitting diode and the
first photodiode array are formed on a nitride semiconductor grown on the front surface and the
back surface of a sapphire substrate, and the second The light emitting diode and the second
photodiode array are formed on a nitride semiconductor grown on the front surface and the back
surface of the sapphire substrate.
[0026]
With such a configuration, even in the push-pull type condenser speaker, the efficiency of
photoelectric conversion can be increased, and more stable characteristics can be obtained.
[0027]
04-05-2019
6
Further, a capacitor speaker according to the present invention includes a transparent movable
electrode having electrical conductivity, a first fixed electrode, and a second fixed electrode, and
the first fixed electrode and the second fixed electrode are One end of a photodiode row
consisting of a plurality of photodiodes connected in series is connected to the transparent
movable electrode of the step-up transformer, and the other end of the photodiode row is
connected to the step-up transformer A light emitting diode is connected to the center tap on the
secondary side of the light emitting diode so as to irradiate light to the photodiode row, a DC
power supply is connected to both terminals of the light emitting diode, and an acoustic signal
source is connected to the step-up transformer. Are connected, and light from the light emitting
diode is irradiated to at least a part of the transparent movable electrode.
[0028]
With such a configuration, it is possible to obtain irradiation of light from the condenser speaker
together with the sound wave, which makes it possible to check the operating condition, and to
obtain a condenser speaker having an electric decoration effect.
[0029]
In the capacitor speaker according to the present invention, the movable electrode is a
transparent movable electrode plate having electrical conductivity, and at least a part of the
transparent movable electrode plate is the first light emitting diode or the second light emitting
diode Light is emitted.
[0030]
With such a configuration, the intensity of light emitted from the condenser speaker changes
with the acoustic signal, and it is possible to produce a further illumination effect.
[0031]
Further, the condenser speaker according to the present invention is characterized in that a
removable filter is provided between the first fixed electrode and the movable electrode.
[0032]
Such a configuration makes it possible to realize a condenser speaker having an air cleaning
function.
[0033]
04-05-2019
7
In the method of driving a condenser speaker according to the present invention, the first light
emitting diode is caused to emit light by a first output outputted from the first LED control unit
according to the acoustic signal, An electric field between the first fixed electrode and the
movable electrode is applied by applying a voltage generated from the first photodiode row to
the first fixed electrode of the capacitor speaker according to the light emission intensity of the
light emitting diode. Driving the movable electrode in accordance with the change of the voltage
of the first photodiode array, the detection voltage divided by the dividing resistors connected in
parallel to the first And a voltage obtained by adding a DC bias voltage to the acoustic signal is
input to the first LED control unit, and the detected voltage is Wherein the generating the first
output corresponding to the voltage difference between the voltage obtained by adding a DC bias
to said acoustic signal from said first LED controller.
[0034]
With such a configuration, a high voltage modulation signal is obtained by irradiating a plurality
of photodiode rows connected in series with light from the LED modulated by an acoustic signal,
and the high voltage modulation signal is applied between parallel plate electrodes. The moving
electrode is mechanically vibrated by the coulomb force of the charge generated to generate a
sound wave, and the divided high voltage modulation signal is negatively fed back to control the
drive current of the LED to the human body. The stabilization of temperature characteristics can
be realized while eliminating the risk of electric shock.
[0035]
In the method of driving a condenser speaker according to the present invention, the first light
emitting diode emits light by a first output outputted from the second LED control unit according
to the acoustic signal, and the second light emitting diode emits light. The second light source
causes the second light emitting diode to emit light by a second output whose acoustic signal
component is in reverse phase with respect to the first output outputted from the LED control
unit, and the second light emitting diode according to the light emitting intensity of the first light
emitting diode. A first voltage generated from the first photodiode array is applied to the first
fixed electrode of the capacitor speaker, and a second voltage generated from the second
photodiode array according to the light emission intensity of the second light emitting diode
Voltage is applied to the second fixed electrode of the capacitor speaker, and the movable
electrode is driven according to a change in electric field between the first fixed electrode and the
second fixed electrode. And, from the voltage generated from the first photodiode array,
negatively detect the divided detection voltage divided by the dividing resistor connected in
parallel to the first photodiode array to the second LED control unit, A voltage obtained by
adding a DC bias to the acoustic signal is input to the second LED control unit, and the first
output is generated according to a voltage difference between the detected voltage and a voltage
obtained by applying a DC bias to the acoustic signal. Generating the second output from the
04-05-2019
8
second LED control unit.
[0036]
With such a configuration, it is possible to realize stabilization of temperature characteristics
while eliminating the risk of electric shock to the human body even for a push-pull type
condenser speaker.
[0037]
The present invention has a configuration that does not use a capacitor in place of the
conventional Cockcroft-Waltron circuit, and further provides a stable sound quality by providing
a circuit that eliminates the influence of environmental changes due to operating temperature
etc. A small (especially thin) and long-life condenser speaker can be provided.
[0038]
The block diagram of the condenser speaker in 1st Embodiment The voltage characteristic chart
in each point of the condenser speaker in 1st Embodiment The block diagram of the condenser
speaker in 2nd Embodiment The block diagram of the condenser speaker in 3rd Embodiment
Voltage characteristic chart at each point of the capacitor speaker in the third embodiment A
cross-sectional view of a package equipped with a component for electric signal processing of the
capacitor speaker in the fourth embodiment For electric signal processing of the capacitor
speaker in the fifth embodiment Cross-sectional view of a package having a component mounted
thereon Configuration view of a capacitor speaker in the sixth embodiment Voltage characteristic
chart at each point of the capacitor speaker in the sixth embodiment Circuit of a capacitor
speaker with an air cleaning function in the seventh embodiment Diagram Configuration diagram
of conventional condenser speaker Voltage characteristic chart at each point of condenser
speaker
[0039]
(First Embodiment) FIG. 1 shows a circuit configuration of a condenser speaker system according
to a first embodiment of the present invention.
The AC (AC) acoustic signal output from the acoustic signal source 1 is applied with a DC bias
voltage generated from the variable bias power supply 3 via the coupling capacitor 2 and is input
to the positive side input terminal of the operational amplifier 4.
04-05-2019
9
The resistive element 5 connected in series to the variable bias power supply 3 prevents the
acoustic signal output from the acoustic signal source 1 from flowing to the ground side via the
variable bias power supply 3.
[0040]
The output of the operational amplifier 4 is connected to the LED (light emitting diode) 7 via the
LED driver 6, and the drive current of the LED 7 changes according to the output voltage of the
operational amplifier 4, and the light emission intensity of the LED 7 changes.
That is, the operational amplifier 4 and the LED driver 6 constitute an LED control unit that
modulates the light emission intensity of the LED 7 according to the voltage of the acoustic signal
which is the input signal.
[0041]
A photodiode row 8 in which a plurality of photodiodes are connected in series is disposed in the
vicinity of the light irradiation surface of the LED 7.
If, for example, 1000 photodiodes each having a photovoltaic power of about 0.6 V are
connected in series, and a sufficient amount of light is generated to generate photovoltaic power
from the LED 7 to all the photodiodes of the photodiode array 8, A voltage of about 600 V is
generated at both ends of the photodiode row.
[0042]
One end of the photodiode array 8 is connected to the ground, and the other end is connected to
the movable electrode 11.
Further, the photodiode array 8 is provided with a bleeder resistor 9 composed of two dividing
04-05-2019
10
resistors 9a and 9b in order to reduce the time constant.
Thus, when the light irradiation is stopped, the high voltage generated at both ends of the
photodiode row 8 is discharged quickly, and the decrease in the operating frequency of the entire
circuit is suppressed.
[0043]
Note that the dividing resistors may substantially divide the resistors.
For example, it may be composed of two or more resistive elements, or conversely, may be
composed of an integral resistive element having a dividing point.
[0044]
As shown in FIG. 1, a bleeder resistor 9 consisting of two split resistors 9 a and 9 b is connected
in parallel to both ends of the photodiode array 8, and the split point S 1 of the two split resistors
9 a and 9 b corresponds to that of the operational amplifier 4. Connected to negative input
terminal (negative feedback connection).
[0045]
The voltage at both ends of the photodiode array 8 is simply divided by the resistance ratio of the
dividing resistors 9a and 9b.
For example, division point S1 is provided at a point where voltage division ratio = 1000: 1 (=
division resistance ratio 9a: 9b), and the potential at this division point S1 is set to V S1.
V S1 includes a DC voltage of about 0.6 V, and the DC bias voltage of the variable bias power
supply 3 corresponds to this DC voltage.
[0046]
04-05-2019
11
FIG. 2 shows temporal changes in voltages V A1, V S1 and V M1 at points A1, S1 and M1 based
on the potential at point M1 in the circuit shown in FIG.
[0047]
According to the above circuit configuration, the output voltage of the photodiode row 8 is
modulated to follow the acoustic signal from the acoustic signal source 1, and the capacitor
speaker can be driven by this output voltage.
[0048]
The mechanical portion of the condenser speaker includes a fixed electrode 10 provided with an
opening and a movable electrode (vibrating electrode) 11.
The fixed electrode 10 is made of, for example, stainless steel.
The movable electrode 11 is formed of, for example, a laminated structure such as a polyester
film to which an aluminum foil is bonded, and both ends thereof are held by an insulating
damper 12 made of, for example, urethane rubber.
That is, the fixed electrode 10 and the movable electrode 11 are provided to face each other at a
predetermined distance apart from each other, and are electrically insulated.
[0049]
That is, a parallel plate capacitor is formed by the fixed electrode 10 and the movable electrode
11.
Then, assuming that the photovoltaic power from the photodiode array 8 is Vp and the capacity
of the capacitor is Cx, the charges induced on the electrodes are Cx · Vp, and the electric field
strength between the electrodes is d between the electrodes. For example, Vp / d.
04-05-2019
12
As a result, the coulomb force received by the two electrodes is the product Cx · Vp <2> / d of
their products.
Since this coulomb force temporally changes according to the acoustic signal, the movable
electrode 11 mechanically vibrates to generate a sound wave, and the sound wave is output
through the aperture of the fixed electrode 10.
[0050]
As described above, the bleeder resistors (dividing resistors 9a and 9b) play a role in detecting
the voltage generated from the photodiode array 8 and at the same time with a role in reducing
the time constant.
Assuming that the resistance value of the bleeder resistance is Rx (= Ra + Rb), this capacitor
speaker has a time constant determined by the product Rx · Cx.
Ra and Rb are resistance values of the dividing resistors 9a and 9b, respectively.
[0051]
Considering that the upper limit of the frequency in the human audible sound range is about 20
kHz, it is necessary to drive the condenser speaker at this frequency.
Therefore, the acoustic signal frequency can be reproduced by the condenser speaker by
satisfying the condition of 1 / (Rx · Cx)> 20 KHz.
[0052]
The sound wave output from the condenser speaker is not necessarily limited to the audible
sound.
04-05-2019
13
If necessary, the ultrasonic wave can be generated from the condenser speaker by setting the
time constant to a high frequency equal to or higher than the audio frequency and setting the
time constant to a smaller value.
[0053]
Further, when the acoustic signal is PWM-modulated, if the sampling frequency is, for example,
about 10 times that of the acoustic signal, that is, 200 kHz, there is a risk that noise generated
due to the high frequency may be mixed in the condenser speaker.
However, since the configuration of the condenser speaker based on the above time constant
functions as a low pass filter, there is an effect of blocking such noise.
[0054]
Next, the stable driving principle of the capacitor speaker using the negative feedback of the
operational amplifier 4 will be described.
[0055]
The operational amplifier 4 shown in FIG. 1 operates as a differential amplifier.
Therefore, an electric signal (for example, a voltage obtained by multiplying the voltage
difference by a constant amplification factor) corresponding to the voltage difference between
the detection voltage S1 input to the negative input terminal of the operational amplifier 4 and
the input voltage of the positive input terminal is output. Be done.
[0056]
Even in this case, the light intensity of the LED 7 or the output voltage of the photodiode array 8
is decreased due to, for example, an increase in environmental temperature, and the input
voltage to the positive input terminal and the input voltage to the negative input terminal When
04-05-2019
14
the voltage difference between the operational amplifier 4 and the amplifier 7 increases, the
output voltage of the operational amplifier 4 increases, the drive current of the LED 7 increases
via the LED driver 6, and the light intensity of the LED 7 increases.
As a result, the output voltage of the photodiode row 8 and the detection voltage V S1 rise, and
the voltage difference changes in the direction of reduction.
If the luminous intensity of the LED 7 or the output voltage of the photodiode array 8 rises due
to a decrease in environmental temperature or the like, the operational amplifier 4 operates in
the opposite manner to the above.
[0057]
That is, since the detection voltage S1 is negatively fed back, the operational amplifier 4 operates
in the direction of canceling out the change of the detection voltage S1 due to the environmental
temperature or the like, and the stable operation becomes possible.
[0058]
Second Embodiment In the first embodiment, an integrated circuit can be used as the LED driver
6, but a power MOSFET may be used instead.
[0059]
In FIG. 3, the output of the operational amplifier 4 is connected to the gate terminal of the nchannel power MOSFET 13 as an LED driver.
The power MOSFET 13 supplies the current of the LED 7 such as a blue light emitting diode by
the power supply 14 with a DC voltage of 6V.
The resistance element 39 is a resistance element for LED protection.
[0060]
Thus, cost can be reduced by using a power MOSFET instead of the LED driver.
04-05-2019
15
[0061]
Third Embodiment FIG. 4 shows the structure of a condenser speaker system according to a third
embodiment of the present invention.
The AC (AC) acoustic signal output from the acoustic signal source 1 is applied with a DC bias
voltage generated from the variable bias power supply 3 through the coupling capacitor 2 and is
input to the positive side input terminal of the operational amplifier 15 having a complementary
output terminal. It is input.
As in the first embodiment, a resistive element 5 is connected in series to the variable bias power
supply 3.
[0062]
The complementary output of the operational amplifier 15 is connected to the first LED driver
16R and the second LED driver 16L.
[0063]
As in the first embodiment, the first and second LED drivers 16R and 16L control the LED drive
current according to the output of the operational amplifier 15, and the first LED 17R and the
second LED 17L Drive each.
[0064]
It should be noted here that the electric signals output from the first and second LED drivers 16R
and 16L have the same DC bias voltage component and the acoustic signal components in
opposite phase.
Therefore, the photovoltaic power generated in the first photodiode row 18R and the second
photodiode row 18L has the same direct current component by being irradiated with light from
the first LED 17R and the second LED 17L. The acoustic signals of opposite phase are
04-05-2019
16
superimposed and applied to each of them.
[0065]
Similar to the first embodiment, the first and second photodiode rows 18R and 18L are disposed
in the vicinity of the irradiation surfaces of the light from the first and second LEDs 17R and 17L,
respectively.
For example, 1000 photodiodes each having a photovoltaic power of about 0.6 V, for example,
are connected in series, and photovoltaics are applied to all the photodiodes of the first and
second LEDs 17R, 17L to the first and second photodiode rows 18R, 18L. If light with a sufficient
amount of light is generated to generate power, a voltage of about 600 V is generated at both
ends of the first and second photodiode rows 18R and 18L.
[0066]
First and second bleeder resistors 19R and 19L are connected in parallel to the first and second
photodiode rows 18R and 18L, respectively, and these first and second bleeder resistors 19R and
19L are They are set to the same resistance value.
[0067]
The first bleeder resistor 19R is configured by series connection of two divided resistors 19Ra
and 19Rb.
The detection voltage V S2 at the dividing point S2 by the dividing resistors 19Ra and 19Rb is
input to the negative input terminal of the operational amplifier 15.
[0068]
The first LED driver 16R, the first LED 17R, and the first bleeder resistor 19R collectively
constitute a negative feedback circuit of the operational amplifier 15 to ensure stable operation
of the entire system.
04-05-2019
17
[0069]
The mechanical portion of the capacitor speaker includes a first fixed electrode 20R provided
with an opening, a second fixed electrode 20L provided with an opening, and a movable
electrode 21.
The first and second fixed electrodes 20R and 20L are made of, for example, stainless steel.
Both ends of the movable electrode 21 are held by the insulating damper 22.
The materials and structures of the movable electrode 21 and the insulating damper 22 may be
the same as those of the first embodiment.
[0070]
That is, a pair of parallel plate capacitors is formed by the first fixed electrode 20R and the
second fixed electrode 20L.
Then, a signal voltage in which an acoustic signal is added to a DC high voltage is applied
between the electrodes of each capacitor.
Here, since the operational amplifier 15 outputs in a complementary manner, vibration voltages
whose acoustic signal components are in opposite phase are applied to the first fixed electrode
20R and the second fixed electrode 20L.
[0071]
As a result, when the attractive force from one of the movable electrodes 21 becomes strong, the
other can be functioned as a push-pull type condenser speaker in which the attractive force
becomes weak.
[0072]
04-05-2019
18
FIG. 5 shows a graph in which the horizontal axis is a time axis for each voltage V X4 and V Y4 of
the first fixed electrode 20R and the second fixed electrode 20L, with the movable electrode 21
as a reference point A4.
[0073]
It can be seen that the voltage relationship between the fixed electrode and the movable
electrode is similar to the voltage relationship of the capacitor speaker using the conventional
transformer shown in FIG.
That is, when viewed from the movable electrode 21, the coulomb force changes in accordance
with the acoustic signal in the first fixed electrode 20R and the second fixed electrode 20L which
are the left and right fixed electrodes.
The movable electrode 21 is vibrated by the coulomb force to generate a sound wave, and the
sound wave is output through the opening of the first fixed electrode 20R and the second fixed
electrode 20L.
[0074]
As described above, by the configuration of the movable electrode 21, the first fixed electrode
20R, and the second fixed electrode 20L, a push-pull type capacitor speaker can be provided, and
in particular, the speaker characteristics can be improved in the low frequency range It becomes.
[0075]
In the present invention, it is preferable to ground the fixed electrode side for safety.
For example, if the side generating the acoustic signal is the second fixed electrode 20L, it is safe
for the human body to touch by grounding Y4.
Further, it is possible to ground both of the two fixed electrodes, the first fixed electrode 20R and
the second fixed electrode 20L, and the safety in that case is further enhanced.
04-05-2019
19
[0076]
Also in this embodiment, a power MOSFET may be used instead of the LED driver.
[0077]
Also in the present embodiment, the relationship between the reciprocal of the time constant
determined by the product of the capacitor capacitance between the movable electrode and the
fixed electrode and the bleeder resistance and the operation (drive) frequency of the speaker is
the same as in the first embodiment. It is.
[0078]
Further, in the present embodiment, when the direction (polarity) of the photodiode in the high
voltage generating portion is opposite to that in the first and second embodiments, that is, the
potential of the movable electrode becomes lower than the potential of both fixed electrodes.
Although the embodiment has been shown, the direction of the photodiode may be reversed and
the potential of the movable electrode may be set higher than the potentials of both fixed
electrodes as in the first and second embodiments. In the second embodiment, the direction of
the photodiode may be reversed.
Also in other embodiments, although not particularly mentioned, it is possible to reverse the
orientation of the photodiode.
[0079]
(Fourth Embodiment) FIG. 6A is an example of a cross-sectional view in which components for
processing electrical signals of the first embodiment are mounted in one package.
[0080]
6A shows that the control unit 23 corresponding to the operational amplifier 4 and the LED
driver 6 in the electronic circuit shown in FIG. 1, the light emitting element unit 24
corresponding to the LED 7, and the light receiving element unit 25 corresponding to the
photodiode row 8 It is shown mounted on the frames 26a, 26b.
04-05-2019
20
[0081]
The coupling capacitor 2 and the resistance element 5 in the electronic circuit shown in FIG. 1
may be incorporated in the control unit 23 or may be connected to an external terminal formed
of a lead frame.
Similarly, the bleeder resistance may be built in the control unit 23 or the light receiving element
unit 25 or may be connected to the outside via the lead frames 26a and 26b.
[0082]
The control unit 23, the light emitting element unit 24, and the light receiving element unit 25
are all connected to the lead frames 26a to 26c by bonding wires 27 made of, for example, gold
or copper.
Alternatively, the light receiving element unit 25 may be formed of, for example, a silicon
photodiode, and the control unit 23 may be formed on the same chip by being formed of an
integrated circuit on a silicon substrate.
[0083]
The light emitting element portion 24 and the light receiving element portion 25 are provided to
face each other via the light transmitting resin 28, and the light receiving element portion 25 is
disposed in the vicinity of the irradiation surface of light from the light emitting element portion
24.
[0084]
Furthermore, the whole is covered with a light shielding resin 29 for mold sealing, and the
control unit 23, the light emitting element unit 24 and the light receiving element unit 25 are
configured as an integrated package.
[0085]
In FIG. 6 (a), the lead frames 26a and 26b are respectively provided only on one side of the
package, but not limited to one side, and may have external terminals on both sides, if necessary.
04-05-2019
21
It goes without saying that the shape and configuration of the lead frame can be freely designed.
[0086]
With the above configuration, the drive current output from the control unit 23 causes the LED
of the light emitting element unit 24 to emit light, and the light emitted from the light emitting
element unit 24 passes through the translucent resin 28 and the light receiving element unit 25.
Generate photovoltaic power.
That is, the voltage generated in the photodiode row 8 that is the light receiving element unit 25
is output as an output voltage, for example, by the bonding wire 27 via the lead frame
functioning as a connection terminal to the outside.
A capacitor speaker (not shown) is driven by the output voltage of the photovoltaic power to
generate an acoustic wave.
[0087]
By thus mounting the control unit 23, the light emitting element unit 24 and the light receiving
element unit 25 in an integrated package, further reduction in size and weight can be realized.
In addition, since the temperature difference between the two becomes extremely small and all
the elements operate at substantially the same temperature, the reliability for stable driving of
the light emitting element unit 24 by the temperature compensation of the control unit 23 is
further improved.
[0088]
Although this embodiment has described the case where the circuit configuration of the first
embodiment is packaged, the power driver may be used instead of the LED driver as described in
the second embodiment, or the other equivalent. Naturally, it may be replaced by one having a
function as an LED drive circuit.
04-05-2019
22
[0089]
Further, FIG. 6A shows an example in which the control unit 23 and the light receiving element
unit 25 are integrated on a single silicon substrate on a single chip, but as shown in FIG. 6B, the
light receiving element unit 25 and the control unit 23 may be separately prepared and
connected by a bonding wire 27.
Furthermore, in this case, as shown in FIG. 6C, the vertical relationship between the light emitting
element unit 24 and the light receiving element unit 25 may be reversed.
[0090]
It is also possible to form the light emitting element unit 24 and the control unit 23 in the same
chip.
In this case, the integrated circuit of the control unit 23 may be an integrated circuit made of
silicon, a compound semiconductor as the light emitting element unit 24, and both mixed
together using SOI (Silicon On Insulator) technology or SOS (Silicon On Sappire) technology. It is
possible.
[0091]
Furthermore, the light emitting element portion 24 and the light receiving element portion 25
can be integrated on the same substrate by using crystal growth of nitride semiconductor (for
example, GaN) on the front and back surfaces of the sapphire substrate 42.
In FIG. 6D, the LED as the light emitting element portion 24 and the photodiode row as the light
receiving element portion 25 are formed on the nitride semiconductor grown on the front and
back surfaces of the sapphire substrate 42 and integrated with the control portion 23 An
example implemented in the package of
The light from the light emitting element unit 24 is irradiated to the light receiving element unit
04-05-2019
23
25 through the sapphire substrate 42, so the translucent resin 28 is not necessary.
[0092]
In this case, light emission and light reception can be performed at the same wavelength by the
LED as the light emitting element unit 24 and the photodiode row as the light receiving element
unit 25, and the efficiency of photoelectric conversion can be enhanced.
Furthermore, in LED light emission of a nitride semiconductor, there is a tendency to shift to a
short wavelength side as the number of injection carriers increases, so there is also an advantage
that the light absorptivity of the nitride semiconductor photodiode array increases.
The LEDs of the light emitting element unit 24 may be a plurality of rows (arrays), which is the
same as in the other embodiments.
[0093]
6D shows an example in which the stacked structure of the light emitting element 24, the
sapphire substrate 42, and the light receiving element 25 and the control unit 23 are mounted
on an integrated package, but only the stacked structure is integrated. It may be implemented in
a package of
[0094]
In addition, as a form of a package, various forms, such as DIP, SOP, QFP, QFN, and BGA, are
employable.
All these points are the same as in the other embodiments.
[0095]
(Fifth Embodiment) FIG. 7 is an example of a cross-sectional view in which components for
04-05-2019
24
processing electrical signals of the third embodiment are mounted in one package.
In the third embodiment, two sets of the combination of the light emitting element and the light
receiving element are used. FIG. 7 shows that even in such a case, mounting in the same package
is possible.
[0096]
7A shows a control unit 23 corresponding to the operational amplifier 15 and the first and
second LED drivers 16R and 16L in the electronic circuit shown in FIG. 4, and a light emitting
element unit corresponding to the first and second LEDs 17R and 17L. Light receiving element
sections 25R and 25L corresponding to 24R and 24L and first and second photodiode rows 18R
and 18L are shown mounted on lead frames 26c, 26e and 26d.
[0097]
The control unit 23, the light emitting element units 24R and 24L, and the light receiving
element units 25R and 25L are all connected to the lead frames 26c to 26e by bonding wires 27
made of, for example, gold or copper.
[0098]
The light emitting element portion 24R and the light receiving element portion 25R are provided
to face each other via the light transmitting resin 28R, and the light receiving element portion
25R is disposed in the vicinity of the irradiation surface of light from the light emitting element
portion 24R.
Similarly, the light emitting element portion 24L and the light receiving element portion 25L are
provided to face each other via the translucent resin 28L, and the light receiving element portion
25L is disposed in the vicinity of the irradiation surface of light from the light emitting element
portion 24L. Be done.
[0099]
Furthermore, the whole is covered with a light shielding resin 29 for mold sealing, and the
control unit 23, the light emitting element units 24 (24R, 24L), and the light receiving element
units 25 (25R, 25L) are configured as an integrated package.
04-05-2019
25
[0100]
Further, in FIG. 7A, the light receiving element sections 25R and 25L are formed by, for example,
photodiodes made of silicon, and the control section 23 is also formed by an integrated circuit on
a silicon substrate, thereby being integrated on a single chip. Although an example is shown, as
shown in FIG. 7 (b), the light receiving element sections 25R and 25L and the control section 23
may be separately prepared and connected by the bonding wire 27, and further shown in FIG. 7
(c). As a matter of course, the vertical relationship between the light receiving element portions
25R and 25L and the light emitting element portions 24L and 24R may be reversed.
In the figure, reference numerals 26c to 26g denote lead frames.
[0101]
In FIG. 7, the lead frames 26c to 26g are provided only on one side of the package, but the lead
frames are not limited to one side, and may have external terminals on both sides. It goes without
saying that the shape and configuration can be designed freely.
[0102]
Further, similarly to the example shown in FIG. 6 (d), also in this embodiment, a laminated
structure in which the light emitting element portion and the light receiving element portion are
formed on the front and back surfaces of the sapphire substrate may be used.
[0103]
In the present embodiment, the case where the circuit configuration of the third embodiment is
packaged has been described, but even if a power MOSFET is used instead of the LED driver, it
has a function as another equivalent LED drive circuit. Naturally, it may be replaced by.
[0104]
The coupling capacitor 2 and the resistance element 5 in the electronic circuit shown in FIG. 4
may be incorporated in the control unit 23 or may be connected (externally attached) to an
external terminal formed of a lead frame. It may be built in the light receiving element unit 25L,
04-05-2019
26
25R or the control unit 23, or may be externally connected (externally connected) via a lead
frame.
This is the same in the fourth embodiment.
[0105]
Sixth Embodiment FIG. 8 is a circuit diagram of a condenser speaker system according to a fourth
embodiment.
The mechanism portion of the condenser of the system includes first and second fixed electrodes
34R and 34L provided with openings and a transparent movable electrode (vibrating electrode)
32.
Each of the first and second fixed electrodes 34R and 34L is made of, for example, stainless steel.
The transparent movable electrode 32 is formed of, for example, a laminated structure in which a
conductive thin film 31 is formed on a thin transparent acrylic resin 30, and both ends thereof
are held by an insulation damper 33 made of, for example, urethane rubber. That is, each of the
first and second fixed electrodes 34R and 34L and the transparent movable electrode 32 are
provided to face each other with a predetermined distance therebetween, and are electrically
insulated.
[0106]
The thickness of the transparent acrylic resin 30 is, for example, 0.5 mm, and the conductive thin
film 31 is, for example, a metal thin film such as gold formed by vacuum evaporation, and the
thickness is 50 nm.
[0107]
As in the first and third embodiments, the photodiode row 37 is disposed in the vicinity of the
04-05-2019
27
plane irradiated with the light from the LED 36.
If, for example, 1000 photodiodes each having a photovoltaic power of about 0.6 V are
connected in series and all the photodiodes of the photodiode row 37 are irradiated with light of
a light amount sufficient to generate the photovoltaic power from the LED 36, A voltage of about
600 V is generated at both ends of the photodiode row 37.
[0108]
One end of the photodiode array 37 is connected to the transparent movable electrode 32, and
the other end is connected to the center tap on the secondary side of the step-up transformer 38.
In addition, 39 is a resistive element for LED protection.
[0109]
Both terminals of the secondary side of the step-up transformer 38 are connected to the first and
second fixed electrodes 34R and 34L.
[0110]
A negative charge is charged on the transparent movable electrode 32 between the transparent
movable electrode 32 and the first and second fixed electrodes 34L and 34R by a voltage
generated by the photodiode row 37.
[0111]
Here, when the acoustic signal source 40 is applied to the primary side of the step-up
transformer 38, the acoustic signal is superimposed on the first and second fixed electrodes 34L
and 34R connected to the secondary side of the step-up transformer 38. Applied.
The change in electric field strength between the first and second fixed electrodes 34R and 34L
according to the acoustic signal mechanically vibrates the transparent movable electrode 32 to
generate a sound wave, and the sound wave is generated by the first and second sound waves. It
is output through the openings of the fixed electrodes 34R, 34L.
04-05-2019
28
[0112]
By guiding and irradiating a part of the irradiation light from the LED 36 to the end of the
transparent acrylic resin 30 during this series of operations, it is possible to cause the condenser
speaker that is the acoustic conversion unit to emit light.
[0113]
By providing fine irregularities on the surface of the transparent acrylic resin 30, irregular
reflection occurs on the surface of the light, and the light can be viewed from the outside through
the openings of the first and second fixed electrodes 34R and 34L. it can.
In this case, since the LED 36 is made to emit light by the power supply 35, a stable light
intensity can be obtained.
[0114]
With the above-described configuration, when the condenser speaker emits light, the operating
state can be clearly understood, and an electric decoration effect can be obtained.
[0115]
FIG. 9 shows the potential V A8 of the transparent movable electrode 32, the potential V Y8 of
the first fixed electrode 34R, and the potential V X8 of the second fixed electrode 34L based on
the secondary side center tap point M8 of the step-up transformer 38. Shows the relationship
between
In this embodiment, this voltage relationship is similar to that of a conventional condenser
speaker.
[0116]
Although the case where light reflected from the transparent movable electrode of the capacitor
speaker has a constant luminous intensity has been described here, also in the first to third
embodiments, as in this embodiment, transparent acrylic as the movable electrode If the light
04-05-2019
29
from the LED is guided to the transparent movable electrode using the transparent movable
electrode made of a laminated structure of resin and conductive thin film, the light modulated by
the acoustic signal component is extracted to the outside, and the decoration effect is further
achieved. It is also possible to produce
[0117]
The transparent acrylic resin is merely an example of the transparent plate, and it goes without
saying that other transparent resins such as polyethylene and thin glass may be used.
[0118]
Seventh Embodiment FIG. 10 is a circuit diagram of a condenser speaker with an air purifying
function according to a seventh embodiment.
In the present embodiment, a filter 41 for air cleaning is disposed between the movable electrode
22 and the first and second fixed electrodes 20R and 20L in the capacitor speaker shown in FIG.
The filter 41 preferably has a large surface area and is removable.
As such, for example, a HEPA filter etc. correspond.
[0119]
As described above, a high voltage is applied between the first and second fixed electrodes 20R
and 20L and the fixed electrode 22 during the capacitor speaker operation. Therefore, foreign
matter in the air that has passed through the openings of the first and second fixed electrodes 20
L and 20 R is charged and drawn to the movable electrode 22.
[0120]
Therefore, by installing the removable filter 41 having a large surface area between the
04-05-2019
30
electrodes, the condenser speaker can function as an electric dust collecting type air cleaner. If
filter 41 is made removable, regular replacement is easy.
[0121]
In particular, the condenser speaker according to the present invention is compact and
lightweight and is safe for the human body, so that it is possible to provide a speaker with an air
cleaning function that can be easily attached to the wall of a general household.
[0122]
In the present embodiment, an example of the air cleaner using the condenser speaker shown in
FIG. 4 is shown, but in the condenser speaker shown in FIG. 1 or FIG. The same is true even if a
possible filter 41 is installed.
[0123]
DESCRIPTION OF SYMBOLS 1 acoustic signal source 2 coupling capacitor 3 variable bias power
supply 4 operational amplifier 5 resistance element 6 LED driver 7 LED8 photodiode row 9a, 9b
division resistance 10 fixed electrode 11 movable electrode 12 insulation damper 13 power
MOSFET 14 power supply 15 operational amplifier 16R having a complementary output terminal
1st LED driver 16L 2nd LED driver 17R 1st LED 17L 2nd LED 18R 1st photodiode row 18L 2nd
photodiode row 19R 1st bleeder resistance 19L 2nd bleeder resistance 19Ra, 19Rb division
resistance 20R first fixed electrode 20L second fixed electrode 21 movable electrode 22
insulating damper 23 control unit 24, 24R, 24L light emitting element unit 25, 25L, 25R light
receiving element unit 26a, 26b, 26c, 26d, 26e, 26f , 26 g lead frame 27 bonding wire 28 light
transmitting resin 29 light shielding resin 30 transparent acrylic resin 31 conductive thin film 32
transparent movable electrode 33 insulating damper 34L, 34R first and second fixed electrodes
35 power supply 36 LED 37 photodiode array 38 Step-up transformer 39 Resistance element 40
Acoustic signal source 41 Filter 42 Sapphire substrate 51, 53 First and second fixed electrodes
52 Movable electrode 54 Insulating damper 55 DC power supply 56 Step-up transformer 57
Acoustic signal source V A1 Potential of movable electrode V A10 Potential V A4 of movable
electrode 52 Potential V M1 of movable electrode plate 21 Potential V M10 at ground point
Potential V S1 at secondary side center tap position of step-up transformer 56 Detection
potential V X at split point V S2 Fixed electrode 51 Potential V X4 of the first fixed electrode 20L
potential V Y1 The potential V Y4 of the fixed electrode 53 The potential V M8 of the second
fixed electrode 20 R The potential V A8 of the secondary side center tap position of the step-up
transformer 38 The potential V of the transparent movable electrode 32 Y 8 The potential V X of
the first fixed electrode 34 R The potential of the second fixed electrode 34L
04-05-2019
31

Download Report