close

Вход

Забыли?

вход по аккаунту

?

DESCRIPTION JPS62155698

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 JPS62155698
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
power saving drive device in a drive circuit of a capacitive loudspeaker such as, for example, a D
/ A convertible high polymer piezoelectric headphone. (Prior Art) Capacitive loudspeakers of the
type described above are known as having a digital signal as a drive signal, which itself converts
it into an analog signal due to its internal structure to generate voice. In this case, since the drive
signal is a digital signal, there are naturally two types of voltages: VH (VH) 0) and 0 voltage. The
drive circuit of a conventional capacitive loudspeaker (hereinafter referred to as a capacitive
load) will be described with reference to FIG. 2. Reference numeral 1 denotes an operational
amplifier, a positive power supply 2 supplies positive voltage + VDD to a power supply terminal
1a, and a power supply terminal 1b A negative voltage -Vss is applied from the negative power
supply 3 to operate. The inverting input terminal 1C of the operational amplifier 1 is connected
to the input terminal 5 via the resistor 4 (resistance value R1) and can be supplied with the input
voltage Vi. The non-inverting input terminal 1d of the operational amplifier 1 is grounded. There
is. The base of the transistor 6.7 is connected to the output terminal 1 e of the operational
amplifier 1, the collector of the transistor 6 is connected to the positive power supply 2, and the
collector of the transistor 7 is connected to the negative power supply 3. The emitter of the
transistor 6.7 is connected to the other end of the capacitive load 8 (capacitance C) whose
negative terminal is grounded and to the other end of the resistor 9 whose one end is connected
to the inverting input terminal 1C of the operational amplifier 1 The operation of this circuit will
be described below. First, assuming that the driving voltage o is 0, the load stored in the
capacitive load 8 is 0 and then the driving voltage vo becomes VI (the load current flows out
through the transistor 6, and the capacitive load A charge Q = cvH is to be supplied to Q8. For
the sake of simplicity and practically no problem at all, we will ignore the energy radiated into
space as sound and proceed with the explanation. At this time, energy of WL = C?vH 2/2 is
11-04-2019
1
stored in the capacitive load 8. When the drive voltage becomes 0 again, a load current flows
from the transistor 7 this time, and the charge amount of the capacitive load 8 becomes Q = O.
That is, the energy W = C-vH2 / 2 stored in the load in this process has been consumed.
(Problems to be Solved by the Invention) As described above, in the conventional circuit, even
when the power consumption of the transistor 6.7 is ignored, the change in drive voltage of one
cycle (0 ? VH? + Q) Certainly, consumption of energy W = C-vH2 / 2 will occur.
Incidentally, assuming that the drive voltage vH is 10, the capacity of the capacitive load 8 is I11
?F, and the number of cycles per second is 44.1 KHz, the power consumption is about 0.22 W.
In particular, in battery-operated equipment, the battery life is critical and the need for calmness
consumption is limited, so even the power consumption generated by the above mechanism can
not be ignored. become. The present invention has been made to solve this problem. (Means for
Solving the Problems) As means for solving the above problems, the present invention relates to
a series of a switching element and an inductance between a capacitive loudspeaker and an
output circuit for driving the capacitive loudspeaker. When connecting via a circuit, connecting
between the capacitive loudspeaker and the power supply via a second inductance closely
coupled to the inductance, and driving the switching element with the answer loudspeaker In this
configuration, when the capacitive load is not driven, the energy stored in the load is supplied to
the power supply through the second inductance. No unnecessary power consumption will be
returned. (Example) Next, one embodiment of the present invention will be described. The same
reference numerals as in FIG. Explanation In this circuit, a resistor 10 is connected between the
inverting input terminal 1C of the operational amplifier 1 and the output terminal 1e, and a
transistor as a switching element via the resistor 11 at the output terminal 1C. 12 paces are
connected ? ? ? ? The collector of the transistor 12 is connected to the positive 1 (source 2
and the pace is also connected to the positive power supply 2 via the resistor 16) The emitter of
the transistor 12 is connected via the inductance 14 Thus, the capacitive load 8 is connected to
one pole. Further, one side of the capacitive load 8 is connected to the positive power supply 2
via a series circuit of a reverse-wound second inductance 15 and a diode 16 which are closely
coupled to the inductance 14. In this case, assuming that the driving voltage has only two values
of 0 and VH and ignoring the voltage drop of the transistor 12 and the diode 16, the difference
from the one in FIG. It is connected from the emitter side to the capacitive load 8 through the
inductance 14, and the transistor 12 allows only the ON state and the floating state by the output
of the operational amplifier 1, and the capacitive load from the second inductance 15 (inductance
It is connected to the positive power supply 2 via the diode 16 and the diode 14).
The inductance 14.15 is equal in value and electrically well coupled via mutual inductance.
Initially, if the drive T @ voltage vo is zero, then the charge stored in the capacitive load 8 is Q =
0. Next, when the transistor 12 is turned on, v H is approximated to be constant, and di IV H = L
d t + T 5 fi d t is satisfied. Here, if the on-time T1 of the transistor 12 is selected so that ? (Tt /
11-04-2019
2
4r) = 1, ie, T, = ??ID / 2, the amount of charge stored in the capacitive load 8 at t = T1 Is Q = Tl.
The energy stored is C-vH2 / 2, where foldt = CL-vH. Since the current of the inductance 14 at
this time is i = Vo IC1, the energy stored in the inductance 14 is completely equal to the energy
stored in LH2 / 2 = CL-VHz / 2 toner ') and the energy stored in the load 8K. o Therefore, the
sum of the energy possessed by the two is CL-VH2. Next, when the drive current o is brought
into a floating state, the second inductance 15 becomes active via the mutual inductance, and
this tries to cause the current to flow back to the positive power supply 2 via the diode 16 0 The
equation is di IVDD = L stone +, and f zat is l), and the initial condition is + ('l = Vo V / C /' L + Q
(0) = C ииии. If you solve the equation under these conditions, you get 5 charges. The first term is
approximated as ignored if it is regarded as VDD vH. This current stops at 0 at t = ? ? C / 2 (=
Tx). At this time, the charge of the capacitive load 8 is Q = ?stone idt?Q (0) = 0, and completely
disappears from the capacitive load 8. That is, the energy C-vH2 / 2 stored in the capacitive load
8 flows out of the capacitive load 8. ???????????????????????????
? Therefore, the energy of C-vH2 flows out in total. By the way, there must be energy recovery
because the current of the above equation flows into the positive power supply 2, so the energy
inflow to the 0 positive power supply 2 to calculate this can be calculated by f 1 vdt, 1 '1 vdt =
VDD, / 'lT' 5dt = c-vH! (', Get Vl (# VD). Thus, it has been found that the energy supplied to the
capacitive load 8 while the transistor 12 is on is recovered to the power supply while the
transistor 12 is in the 70-tending state.
(Effects of the Invention) Since the present invention is configured as described above, the drive
signal is an 8-bit PCM signal, and the drive signal is divided so as to have an area proportional to
2 (N = O to 7) each. By applying to an area division type direct D / A conversion type capacitive
speaker such as having a diaphragm, still a loudspeaker such as headphones. Since the audio
signal can be converted to sound pressure with low power consumption, its application range is
extremely large.
[0002]
Brief description of the drawings
[0003]
FIG. 1 is a circuit diagram of an embodiment of the present invention, and FIG. 2 is a circuit
diagram of a conventional one 01... Op amp 2 .. positive power supply 3 .. negative power supply
5 .. input terminal 8. и и Heavy load 12 и и и transistor 14 и и и inductance 15 и и и second inductance
16 и и и
11-04-2019
3
Документ
Категория
Без категории
Просмотров
0
Размер файла
12 Кб
Теги
description, jps62155698
1/--страниц
Пожаловаться на содержимое документа