U.S. patent application number 14/527288 was filed with the patent office on 2015-02-26 for ultrasonic transducer driving circuit and ultrasonic image display apparatus.
This patent application is currently assigned to GENERAL ELECTRIC COMPANY. The applicant listed for this patent is GENERAL ELECTRIC COMPANY. Invention is credited to Shinichi Amemiya, Bruno Haider, Krishnakumar Sundaresan.
Application Number | 20150053011 14/527288 |
Document ID | / |
Family ID | 47215736 |
Filed Date | 2015-02-26 |
United States Patent
Application |
20150053011 |
Kind Code |
A1 |
Amemiya; Shinichi ; et
al. |
February 26, 2015 |
ULTRASONIC TRANSDUCER DRIVING CIRCUIT AND ULTRASONIC IMAGE DISPLAY
APPARATUS
Abstract
An ultrasonic transducer driving circuit configured to supply an
output current and/or an output voltage to an output line for
driving an ultrasonic transducer is provided. The ultrasonic
transducer driving circuit includes a first current discharge
circuit configured to allow a current arising from electric charges
accumulated in the ultrasonic transducer to flow from the output
line to ground when the output line is at a positive voltage, and a
second current discharge circuit configured to allow the current
arising from the electric charges accumulated in the ultrasonic
transducer to flow from ground to the output line when the output
line is at a negative voltage. The first current discharge circuit
and the second current discharge circuit are controlled based on
the output current and/or the output voltage.
Inventors: |
Amemiya; Shinichi; (Tokyo,
JP) ; Haider; Bruno; (Ballston Lake, NY) ;
Sundaresan; Krishnakumar; (Clifton Park, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
GENERAL ELECTRIC COMPANY |
Schenectady |
NY |
US |
|
|
Assignee: |
GENERAL ELECTRIC COMPANY
Schenectady
NY
|
Family ID: |
47215736 |
Appl. No.: |
14/527288 |
Filed: |
October 29, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13284156 |
Oct 28, 2011 |
8933613 |
|
|
14527288 |
|
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|
Current U.S.
Class: |
73/606 ;
310/317 |
Current CPC
Class: |
B06B 1/0215 20130101;
G01N 29/44 20130101; G01N 29/34 20130101; G01N 2291/102 20130101;
H01L 41/09 20130101; G01N 2291/048 20130101; G01N 29/06 20130101;
B06B 1/0207 20130101 |
Class at
Publication: |
73/606 ;
310/317 |
International
Class: |
H01L 41/09 20060101
H01L041/09; G01N 29/44 20060101 G01N029/44; G01N 29/06 20060101
G01N029/06 |
Claims
1. An ultrasonic transducer driving circuit comprising: a voltage
output type circuit configured to control an output voltage and to
supply an electrical current to an output line for driving an
ultrasonic transducer; and a buffer amplifier along an output line
of said voltage output type circuit, the buffer amplifier
configured to receive an output voltage of said voltage output type
circuit, said buffer amplifier comprising: a first push-pull
circuit of comprising a first transistor and a second transistor
connected to an output line of the buffer amplifier; and a second
push-pull circuit comprising a third transistor and a fourth
transistor connected between the output line of said buffer
amplifier and a ground, wherein each transistor of said first
push-pull circuit and said second push-pull circuit is configured
to receive a voltage having a predetermined voltage difference
relative to the output voltage of said voltage output type circuit;
wherein the predetermined voltage difference is larger for said
fourth transistor than for said second transistor, such that said
fourth transistor has an ON state based on the output voltage of
said voltage output type circuit when the output line of said
buffer amplifier is at a positive voltage to allow a current
arising from electric charges accumulated in the ultrasonic
transducer to flow from the output line of said buffer amplifier to
the ground; and the predetermined voltage difference is larger for
said third transistor than for said first transistor such that said
third transistor has an ON state based on the output voltage of
said voltage output type circuit when the output line of said
buffer amplifier is at a negative voltage to allow the current
arising from the electric charges accumulated in the ultrasonic
transducer to flow from the ground to the output line of said
buffer amplifier.
2. The ultrasonic transducer driving circuit according to claim 1,
wherein said first transistor and said second transistor are
connected between the output line of said buffer amplifier and a
power supply.
3. The ultrasonic transducer driving circuit according to claim 2,
wherein said first transistor is connected to a positive supply
voltage and said second transistor is connected to a negative
supply voltage.
4. The ultrasonic transducer driving circuit according to claim 1,
wherein: said first transistor and said third transistor are
configured to receive a voltage larger than the output voltage of
said voltage output type circuit; and said second transistor and
said fourth transistor are configured to receive a voltage smaller
than the output voltage of said voltage output type circuit.
5. An ultrasonic image display apparatus comprising an ultrasonic
transducer driving circuit according to claim 1.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. patent application
Ser. No. 13/284,156 filed Oct. 28, 2011, which is hereby
incorporated by reference in its entirety.
BACKGROUND OF THE INVENTION
[0002] The embodiments described herein relate to an ultrasonic
transducer driving circuit and ultrasonic image display
apparatus.
[0003] An ultrasonic transducer driving circuit is a circuit that
outputs pulses comprised of positive pulses and negative pulses to
an output line toward an ultrasonic transducer and drives the
ultrasonic transducer. As this kind of ultrasonic transducer
driving circuit, a voltage output type circuit that controls an
output voltage and supplies an electrical current for driving an
ultrasonic transducer is described in, for example, Japanese
Unexamined Patent Publication No. 2009-101072. In particular, the
voltage output type circuit comprises a positive voltage output
circuit which outputs a positive voltage to the above-mentioned
output line and a negative voltage output circuit which outputs a
negative voltage to the above-mentioned output line. In this
ultrasonic transducer driving circuit, when negative pulses are to
be generated from a state in which the above-mentioned output line
is at a positive voltage, the above-mentioned negative voltage
output circuit is triggered to operate; and when positive pulses
are to be generated from a state in which the above-mentioned
output line is at a negative voltage, the above-mentioned positive
voltage output circuit is triggered to operate.
[0004] When the above-mentioned negative voltage output circuit is
triggered to operate when generating negative pulses from a state
in which the above-mentioned output line is supplied with a
positive voltage, a current arising from electric charges which
have been charged in the above-mentioned ultrasonic transducer
flows in this negative voltage output circuit for a certain period
of time and power is consumed. In turn, when the above-mentioned
positive voltage output circuit is triggered to operate when
generating positive pulses from a state in which the
above-mentioned output line is at a negative voltage, a current
arising from electric charges which have been charged in the
above-mentioned ultrasonic transducer flows in this positive
voltage output circuit for a certain period of time and power is
consumed. Therefore, reducing power consumption becomes a
problem.
BRIEF DESCRIPTION OF THE INVENTION
[0005] In one aspect, an ultrasonic transducer driving circuit
supplies an output current or an output voltage to an output line
for driving an ultrasonic transducer. The ultrasonic transducer
driving circuit includes a first current discharge circuit that,
when the output line is at a positive voltage, allows a current
arising from electric charges accumulated in the ultrasonic
transducer to flow from the output line to ground and a second
current discharge circuit that, when the output line is at a
negative voltage, allows the current arising from electric charges
accumulated in the ultrasonic transducer to flow from ground to the
output line. The operations of the first and the second current
discharge circuits are controlled in accordance with the output
current or the output voltage.
[0006] Here, the output current or the output voltage is a current
or a voltage of an output line of the ultrasonic transducer driving
circuit.
[0007] In another aspect, an ultrasonic transducer driving circuit
includes a current output type circuit that controls an output
current for driving an ultrasonic transducer and a current control
unit that outputs a current to the current output type circuit for
controlling the output current. The current output type circuit
includes a first current discharge circuit that, when the output
line is at a positive voltage, allows a current arising from
electric charges accumulated in the ultrasonic transducer to flow
from the output line to ground and a second current discharge
circuit that, when the output line is at a negative voltage, allows
the current arising from electric charges accumulated in the
ultrasonic transducer to flow from ground to the output line. The
operations of the first current discharge circuit and the second
current discharge circuit are controlled by a current from the
current control unit.
[0008] Here the output current is a current of an output line of
the current output type circuit.
[0009] In yet another aspect, an ultrasonic transducer driving
circuit includes a voltage output type circuit that controls an
output voltage and supplies an electrical current to an output line
for driving an ultrasonic transducer and a first current discharge
circuit and a second current discharge circuit connected to the
output line. The first current discharge circuit is a circuit that,
when the output line is at a positive voltage, allows a current
arising from electric charges accumulated in the ultrasonic
transducer to flow from the output line to ground and the second
current discharge circuit is a circuit that, when the output line
is at a negative voltage, allows the current arising from electric
charges accumulated in the ultrasonic transducer to flow from
ground to the output line. The operations of the first and second
current discharge circuits are controlled by the voltage difference
between the output line and the output of the voltage output type
circuit.
[0010] Here, the output voltage is a voltage of an output line of
the voltage output type circuit.
[0011] In yet another aspect, an ultrasonic transducer driving
circuit includes a voltage output type circuit that controls an
output voltage and supplies an electrical current to an output line
for driving an ultrasonic transducer and a buffer amplifier that is
provided between this voltage output type circuit and the
ultrasonic transducer and takes input of an output voltage of the
voltage output type circuit. The buffer amplifier includes a first
push-pull circuit having a first transistor and a second transistor
connected to an output line of the buffer amplifier and a second
push-pull circuit having a third transistor and a fourth transistor
connected between the output line of the buffer amplifier and a
ground. A voltage having a predetermined voltage difference
relative to the output voltage of the voltage output type circuit
is input to each of the transistors constituting the first
push-pull circuit and the second push-pull circuit. The
predetermined voltage difference is larger for the fourth
transistor than for the second transistor, so that, when the output
line of the buffer amplifier is at a positive voltage, the fourth
transistor, of the second transistor and the fourth transistor,
turns into an ON state in accordance with an output voltage of the
voltage output type circuit, thereby allowing the current arising
from electric charges accumulated in the ultrasonic transducer to
flow from the output line to ground. The predetermined voltage
difference is also larger for the third transistor than for the
first transistor, so that, when the output line of the buffer
amplifier is at a negative voltage, the third transistor, of the
first transistor and the third transistor, turns into an ON state
in accordance with an output voltage of the voltage output type
circuit, thereby allowing the current arising from electric charges
accumulated in the ultrasonic transducer to flow from ground to the
output line.
[0012] Here, the output voltage is a voltage of an output line of
the voltage output type circuit.
[0013] A further aspect includes an ultrasonic image display
apparatus having an ultrasonic transducer driving circuit
pertaining to any of the aspects described above.
[0014] According to the aspects described above, when the output
line is at a positive voltage, the current arising from electric
charges accumulated in the ultrasonic transducer flows from the
output line to ground. When the output line is at a negative
voltage, the current arising from electric charges accumulated in
the ultrasonic transducer flows from ground to the output line.
Thereby, power consumption can be reduced.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is a block diagram showing an exemplary embodiment of
an ultrasonic image display apparatus.
[0016] FIG. 2 is a block diagram showing a transceiving section of
the ultrasonic image display apparatus shown in FIG. 1.
[0017] FIG. 3 is a diagram showing an outlined structure of an
ultrasonic transducer driving circuit in the ultrasonic image
display apparatus shown in FIG. 1.
[0018] FIG. 4 is circuit diagram showing an ultrasonic transducer
driving circuit in the ultrasonic image display apparatus shown in
FIG. 1.
[0019] FIG. 5 is a diagram for explaining how a first current
mirror circuit operates.
[0020] FIG. 6 is a diagram for explaining how a fourth current
mirror circuit operates.
[0021] FIG. 7 is a diagram for explaining how a third current
mirror circuit operates.
[0022] FIG. 8 is a diagram for explaining how a second current
mirror circuit operates.
[0023] FIG. 9 is a circuit diagram showing an ultrasonic transducer
driving circuit of a second embodiment.
[0024] FIG. 10 is a diagram showing a voltage waveform with five
levels of voltages.
[0025] FIG. 11 is a circuit diagram showing another example of an
ultrasonic transducer driving circuit of the second embodiment.
[0026] FIG. 12 is a diagram showing one example of a waveform of an
output voltage that is output from a voltage output type
circuit.
[0027] FIG. 13 is a diagram for explaining how the ultrasonic
transducer driving circuit of the second embodiment operates.
[0028] FIG. 14 is a diagram for explaining how the ultrasonic
transducer driving circuit of the second embodiment operates.
[0029] FIG. 15 is a diagram for explaining how the ultrasonic
transducer driving circuit of the second embodiment operates.
[0030] FIG. 16 is a diagram for explaining how the ultrasonic
transducer driving circuit of the second embodiment operates.
[0031] FIG. 17 is a circuit diagram showing an ultrasonic
transducer driving circuit of a first example of modification to
the second embodiment.
[0032] FIG. 18 is a circuit diagram in which switches were turned
off in the ultrasonic transducer driving circuit shown in FIG.
17.
[0033] FIG. 19 is a circuit diagram showing an ultrasonic
transducer driving circuit of a second example of modification to
the second embodiment.
[0034] FIG. 20 is a circuit diagram showing an ultrasonic
transducer driving circuit of a third embodiment.
[0035] FIG. 21 is a diagram for explaining how the ultrasonic
transducer driving circuit of the third embodiment operates.
[0036] FIG. 22 is a diagram for explaining how the ultrasonic
transducer driving circuit of the third embodiment operates.
[0037] FIG. 23 is a diagram for explaining how the ultrasonic
transducer driving circuit of the third embodiment operates.
[0038] FIG. 24 is a diagram for explaining how the ultrasonic
transducer driving circuit of the third embodiment operates.
DETAILED DESCRIPTION OF THE INVENTION
[0039] In the following, embodiments of the present invention will
be described in detail based on the drawings.
First Embodiment
[0040] To begin with, a first embodiment is described based on
FIGS. 1-8. As shown in FIG. 1, an ultrasonic image display
apparatus 100 includes an ultrasonic probe 101, a transceiver unit
102, an echo data processing unit 103, a display control unit 104,
a display unit 105, an operational unit 106, and a control unit
107.
[0041] The ultrasonic probe 101 is provided with a plurality of
ultrasonic transducers 101a for transmitting and receiving
ultrasonic waves.
[0042] The transceiver unit 102 includes a transmitter unit 1021
and a receiver unit 1022, as shown in FIG. 2. The transmitter unit
1021 supplies an electric signal for transmitting ultrasonic waves
under predetermined scanning conditions to the ultrasonic
transducers 101a, based on a control signal from the control unit
107. The transmitter unit 1021 includes ultrasonic transducer
driving circuits 1 that supply an electric signal for driving the
ultrasonic transducers 101a and causing them to transmit ultrasonic
waves (not shown in FIG. 2; see FIG. 3). Further description about
the ultrasonic transducer driving circuits 1 will be provided
later.
[0043] The receiver unit 1022 performs signal processing such as
A/D conversion, phasing and addition, etc. on an echo signal
received by the ultrasonic probe 2 and outputs resulting echo data
to the echo data processing unit 103.
[0044] The echo data processing unit 103 performs processing for
producing an ultrasonic image on echo data which has been input
from the transceiver unit 102. For example, the echo data
processing unit 103 performs B-mode processing such as logarithmic
compression and envelope detection and Doppler processing such as
quadrature detection and filtering.
[0045] The display control unit 104 performs scan conversion of
data obtained by the echo data processing unit 103 using a scan
converter and produces ultrasonic image data. Then, the display
control unit 104 causes the display unit 105 to display an
ultrasonic image in accordance with the ultrasonic image data.
[0046] The display unit 105 includes an LCD (liquid crystal
display), a CRT (Cathode Ray tube), or any other type of display.
The operational unit 106 includes a keyboard and a pointing device
(not shown) or the like for allowing an operator to enter a command
and information.
[0047] The control unit 107 includes a CPU (Central Processing
Unit). This control unit 107 reads a control program stored in a
memory unit which is not shown and causes respective components of
the ultrasonic image display apparatus 100 to perform their
functions.
[0048] Description about the ultrasonic transducer driving circuits
1 is provided based on FIGS. 3 and 4. The number of the (plural)
ultrasonic transducer driving circuits 1 corresponds to a maximum
number of the ultrasonic transducers 101a which are used for
transmission (only one of them is shown in FIG. 3). Each of the
ultrasonic transducer driving circuits 1 includes a current DAC
(Digital to Analog Converter) 2 and a current output type circuit
3. The current output type circuit 3 controls an output current
flowing through an output line O and supplies electrical currents
to the output line O for driving the corresponding ultrasonic
transducer 101a. This output line O is one example of an embodiment
of an output line.
[0049] In fact, the output line O is the output line of the current
output type circuit 3 and also the output line of each of the
ultrasonic transducer driving circuits 1. The output line of the
current output type circuit 3 is the output line of each of the
ultrasonic transducer driving circuits 1.
[0050] The current DAC 2 includes a positive current DAC 21 and a
negative current DAC 22. The current output type circuit 3 includes
a positive current output type circuit 31 and a negative current
output type circuit 32. The current DAC 2 is one example of an
embodiment of a current control. The current output type circuit 3
is one example of an embodiment of a current output type
circuit.
[0051] The positive current DAC 21 and the negative current DAC 22
output a current for controlling an output current of the positive
current output type circuit 31 and the negative current output type
circuit 32.
[0052] The positive current DAC 21 is connected to the positive
current output type circuit 31. The output current of the positive
current output type circuit 31 is controlled by the current that is
output from the positive current DAC 21 to the positive current
output type circuit 31. The negative current DAC 22 is connected to
the negative current output type circuit 32. The output current of
the negative current output type circuit 32 is controlled by the
current that is output from the negative current DAC 22 to the
negative current output type circuit 32.
[0053] By the way, in conjunction with controlling the output
currents of the positive current output type circuit 31 and the
negative current output type circuit 32, the operations of a second
current mirror circuit 312 and a fourth current mirror circuit 322
which will be described later are controlled. More specifically,
the operations of the second current mirror circuit 312 and the
fourth current mirror circuit 322 are controlled by the currents
that are output from the positive current DAC 21 and the negative
current DAC 22.
[0054] The positive current output type circuit 31 outputs a
positive current to the corresponding ultrasonic transducer 101a.
On the other hand, the negative current output type circuit 32
outputs a negative current to the corresponding ultrasonic
transducer 101a.
[0055] How the positive current output type circuit 31 and the
negative current output type circuit 32 are configured is described
in detail based on FIG. 4. The positive current output type circuit
31 includes a first current mirror circuit 311, a second current
mirror circuit 312, and a positive current switching circuit 313.
The first current mirror circuit 311 is configured with a
transistor Tr1 and a transistor Tr2. The second current mirror
circuit 312 is configured with a transistor Tr3 and a transistor
Tr4. The positive current switching circuit 313 is configured with
a transistor Tr5 and a transistor Tr6. The transistors Tr1 to Tr4
are p-channel type MOSFETs (Metal-Oxide Semiconductor Field-Effect
Transistors). The transistors Tr5, Tr6 are n-channel type
MOSFETs.
[0056] The operations of the first current mirror circuit 311 and
the second current mirror circuit 312 are controlled by the output
current of the positive current DAC 21, as will be described later.
The first current mirror circuit 311 is one example of an
embodiment of a positive current mirror circuit. The second current
mirror circuit 312 is one example of an embodiment of a second
current discharge circuit.
[0057] For the transistors Tr1, Tr2, their gate terminals are
connected to each other and their source terminals are connected to
a power supply voltage +HV. A drain terminal of the transistor Tr1
is connected to a drain terminal of the transistor Tr6 and a drain
terminal of the transistor Tr2 is connected to the output line
O.
[0058] For the transistors Tr3, Tr4, their gate terminals are
connected to each other and their source terminals are connected to
a ground. A drain terminal of the transistor Tr3 is connected to
the transistor Tr5 and a drain terminal of the transistor Tr4 is
connected to the output line O. Besides, a diode D1 is connected
between a drain terminal of the transistor Tr4 and the output line
O. This diode D1 is connected, oriented so that a current flows
from the transistor Tr4 toward the output line O.
[0059] For the transistors Tr5, Tr6, their source terminals are
connected to the positive current DAC 21. A gate terminal of the
transistor Tr5 is connected to a voltage -VrefGND and a gate
terminal of the transistor Tr6 is connected to the output line O.
By the way, -VrefGND is a voltage that is lower by a predetermined
voltage than ground.
[0060] The positive current switching circuit 313 formed of the
transistors Tr5, Tr6 is a differential amplifier circuit in which
the transistor Tr6 will be OFF when the transistor Tr5 is put in an
ON state, whereas the transistor Tr6 will be ON when the transistor
Tr5 is put in an OFF state. The transistor Tr6 is put in an ON
state when the output line O is at a positive voltage and in an OFF
state when the output line O is at a negative voltage. Hence, the
transistor Tr5 is put in an OFF state when the output line O is at
a positive voltage and in an ON state when the output line O is at
a negative voltage.
[0061] The negative current output circuit 32 includes a third
current mirror circuit 321, a fourth current mirror circuit 322,
and a negative current switching circuit 323. The third current
mirror circuit 321 is configured with a transistor Tr7 and a
transistor Tr8. The fourth current mirror circuit 322 is configured
with a transistor Tr9 and a transistor Tr10. The negative current
switching circuit 323 is configured with a transistor Tr11 and a
transistor Tr12. The transistors Tr7 to Tr10 are n-channel type
MOSFETs (Metal-Oxide Semiconductor Field-Effect Transistors). The
transistors Tr11, Tr12 are p-channel type MOSFETs.
[0062] The third current mirror circuit 321 is one example of an
embodiment of a negative current mirror circuit. The fourth current
mirror circuit 322 is one example of an embodiment of a first
current discharge circuit.
[0063] For the transistors Tr7, Tr8, their gate terminals are
connected to each other and their source terminals are connected to
a power supply voltage -HV. A drain terminal of the transistor Tr7
is connected to a drain terminal of the transistor Tr12 and a drain
terminal of the transistor Tr8 is connected to the output line
O.
[0064] For the transistors Tr9, Tr10, their gate terminals are
connected to each other and their source terminals are connected to
a ground. A drain terminal of the transistor Tr9 is connected to
the transistor Tr11 and a drain terminal of the transistor Tr10 is
connected to the output line O. Besides, a diode D2 is connected
between the drain terminal of the transistor Tr10 and the output
line O. This diode D2 is connected to be oriented so that a current
flows from the output line O toward the transistor Tr10.
[0065] For the transistors Tr11, Tr12, their source terminals are
connected to the negative current DAC 22. A gate terminal of the
transistor Tr11 is connected to a voltage +VrefGND and a gate
terminal of the transistor Tr12 is connected to the output line O.
By the way, +VrefGND is a voltage that is higher by a predetermined
voltage than ground.
[0066] The negative current switching circuit 323 formed of the
transistors Tr11, Tr12 is a differential amplifier circuit in which
the transistor Tr12 will be OFF when the transistor Tr11 is put in
an ON state, whereas the transistor Tr12 will be ON when the
transistor Tr11 is put in an OFF state. The transistor Tr12 is put
in an OFF state when the output line O is at a positive voltage and
in an ON state when the output line O is at a negative voltage.
Hence, the transistor Tr11 is put in an ON state when the output
line O is at a positive voltage and in an OFF state when the output
line O is at a negative voltage.
[0067] Then, how an ultrasonic transducer driving circuit 1 of the
present example operates is described. In this ultrasonic
transducer driving circuit 1, a positive current is output from the
positive current output type circuit 31 and a negative current is
output from the negative current output type circuit 32 and
electrical currents for driving the corresponding ultrasonic
transducer 101a are output. This is explained specifically
below.
[0068] First, the first current mirror circuit 311 operates and a
positive current +Io is output. Concretely speaking, as shown in
FIG. 5, a negative current -Ii is input from the positive current
DAC 21 to the positive current output type circuit 31. At this
time, the transistor Tr6 is put in an ON state and there is a
current I6 flowing through this transistor Tr6. This, in
consequence, produces a current I1 flowing through the transistor
Tr1 and a current I2 flowing through the transistor Tr2. This
current I2 is output to the output line O as the positive current
+Io and the voltage of this output line O rises and becomes a
positive voltage.
[0069] Then, the fourth current mirror circuit 322 operates and the
output of the positive current +Io causes discharging of electric
charges accumulated in the ultrasonic transducer 101a. Concretely,
as shown in FIG. 6, instead of the input of the negative current
-Ii from the positive current DAC 21 to the positive current output
type circuit 31, a positive current +Ii is input from the negative
current DAC 22 to the negative current output type circuit 32. At
this time, the transistor Tr11 is put in an ON state and,
therefore, the positive current +Ii produces a current I11 flowing
through the transistor Tr11, a current I9 flowing through the
transistor Tr9, and a current I10 flowing through the transistor
Tr10. This current I10 is a current arising from electric charges
accumulated in the ultrasonic transducer 101a and is one example of
an embodiment of a current flowing from the output line to
ground.
[0070] In turn, the third current mirror circuit 321 operates.
Concretely, the flowing of the current I10 causes a decrease in the
voltage (positive voltage) of the output line O. Then, when the
voltage of the output line O comes to the voltage +VrefGND, the
transistor Tr12 turns into an ON state, whereas the transistor Tr11
turns into an OFF state. As shown in FIG. 7, the turning of the
transistor Tr12 into the ON state produces a current I12 flowing
through this transistor Tr12. This, in consequence, produces a
current I7 flowing through the transistor Tr7 and a current I8
flowing through the transistor Tr8. This current I8 is output to
the output line O as a negative current -Io and the voltage of this
output line O falls and becomes a negative voltage.
[0071] Then, the second current mirror circuit 312 operates and the
output of the negative current -Io causes discharging of electric
charges accumulated in the ultrasonic transducer 101a. Concretely,
as shown in FIG. 8, instead of the input of the positive current
+Ii from the negative current DAC 22 to the negative current output
type circuit 32, the negative current -Ii is input from the
positive current DAC 21 to the positive current output type circuit
31. At this time, the transistor Tr5 is put in an ON state and,
therefore, the negative current -Ii produces a current I5 flowing
through the transistor Tr5, a current I3 flowing through the
transistor Tr3, and a current I4 flowing through the transistor
Tr4. This current I4 is a current arising from electric charges
accumulated in the ultrasonic transducer 101a and is one example of
an embodiment of a current flowing from ground to the output
line.
[0072] The flowing of the current I4 causes an increase of the
voltage (negative voltage) of the output line O. Then, when the
voltage of the output line O comes to the voltage -VrefGND, the
transistor Tr6 turns into an ON state, whereas the transistor Tr5
turns into an OFF state. The turning of the transistor Tr6 into the
ON state produces the current I2 again and the positive current +Io
is supplied to the output line O.
[0073] According to the ultrasonic transducer driving circuit 1 of
the present example, when the output line O is at a positive
voltage, the current arising from electric charges accumulated in
the ultrasonic transducer 101a flows from the output line O to
ground via the fourth current mirror circuit 322. Likewise, when
the output line O is at a negative voltage, the current arising
from electric charges accumulated in the ultrasonic transducer 101a
flows from ground to the output line O via the second current
mirror circuit 312. In this way, the current arising from electric
charges accumulated in the ultrasonic transducer 101a does not flow
through the first current mirror circuit 311 and the third current
mirror circuit 321 and, thus, power consumption can be reduced.
Second Embodiment
[0074] Next, a second embodiment is described. Ultrasonic
transducer driving circuits 50 of the present example are provided
in the transmitter unit 1021 of the ultrasonic image display
apparatus 100 (see FIG. 1 and FIG. 2), as is the case for the
ultrasonic transducer driving circuits 1 of the first
embodiment.
[0075] As shown in FIG. 8, each of the ultrasonic transducer
driving circuits 50 includes a voltage output type circuit 51, a
first current discharge circuit 52, and a second current discharge
circuit 53. The voltage output type circuit 51 controls an output
voltage of an output line O and supplies an electrical current to
an output line O for driving the corresponding ultrasonic
transducer 101a. This output line O is one example of an embodiment
of an output line.
[0076] The output line O is the output line of the voltage output
type circuit 51 and also the output line of each of the ultrasonic
transducer driving circuits 1. The output line of the voltage
output type circuit 51 is the output line of each of the ultrasonic
transducer driving circuits 50.
[0077] The voltage output type circuit 51 is a multi-level pulser
having three or more levels of output voltages. For example, the
voltage output type circuit 51 outputs five levels of voltages as
output voltages, as is illustrated in FIG. 10. This is, however,
not to be regarded as limiting.
[0078] The voltage output type circuit 51 includes an operational
amplifier 511. To this operational amplifier 511, a positive power
supply 512 which supplies a positive supply voltage and a negative
power supply 513 which supplies a negative supply voltage are
connected.
[0079] Besides, a power supply 514 is connected to a non-inverting
input terminal (+) of the operational amplifier 511. On end of this
power supply 514 is connected to the non-inverting input terminal
(+) and the other end is connected to a ground.
[0080] A resistor R1 is connected between an inverting input
terminal (-) of the operational amplifier 511 and the ground. The
other end of a feedback line FL whose one end is connected to the
output line O and having a resistor R2 is connected between this
resistor R1 and the inverting input terminal (-). Thus, by way of
this feedback line FL, the output voltage of the output line O is
divided by the resistor R2 and input to the inverting input
terminal (-).
[0081] The first current discharge circuit 52 and the second
current discharge circuit 53 are provided along the output line O.
In other words, the first current discharge circuit 52 and the
second current discharge circuit 53 are provided between the
voltage output type circuit 51 and the corresponding ultrasonic
transducer 101a. The first current discharge circuit 52 is
configured with a current mirror circuit having transistors Tr21
and Tr22. The second current discharge circuit 53 is configured
with a current mirror circuit having transistors Tr23 and Tr24. The
transistors Tr21 and Tr22 are p-channel type MOSFETs and the
transistors Tr23 and Tr24 are n-channel type MOSFETs.
[0082] For the transistors Tr21 and Tr22, their gate terminals are
connected to each other and their source terminals are connected to
the ultrasonic transducer 101a. A drain terminal of the transistor
Tr21 is connected to the voltage output type circuit 51 and a drain
terminal of the transistor Tr22 is connected to the ground.
[0083] For the transistors Tr23, Tr24, their gate terminals are
connected to each other and their source terminals are connected to
the ultrasonic transducer 101a. A drain terminal of the transistor
Tr23 is connected to the voltage output type circuit 51 and a drain
terminal of the transistor Tr24 is connected to the ground.
[0084] Here, a path between the transistors T21, T22 and an output
terminal of the operational amplifier 511 is assumed as a first
output line O1. A path between the transistors Tr21 to Tr24 and the
ultrasonic transducer 101a is assumed as a second output line O2.
That is, the output line includes the first output line O1 and the
second output line O2. One end of the first output line O1 is
connected to the output terminal of the operational amplifier 511
and the other end branches to connect to the drain terminals of the
transistors Tr21 and Tr23.
[0085] The operations of the first current discharge circuit 52 and
the second current discharge circuit 53 are controlled according to
an output voltage of the voltage output type circuit 51. In the
present example, the operations of the first current discharge
circuit 52 and the second current discharge circuit 53 are
controlled by the voltage difference between the second output line
O2 and the first output line O1. Further details will be provided
later.
[0086] Diodes D21 and D23 are connected at points on the branches
of the first output line O1. The diode D21 is connected to be
oriented so that a current flows from the transistor Tr21 toward
the output terminal of the operational amplifier 511. The diode D23
is connected to be oriented so that a current flows from the output
terminal of the operational amplifier 511 toward the transistor
Tr23.
[0087] However, the diodes D21 and D23 may not necessarily be
provided.
[0088] A diode D22 is connected between the transistor Tr22 and the
ground. A diode D24 is connected between the transistor Tr24 and
the ground. The diode D22 is connected to be oriented so that a
current flows from the transistor Tr22 toward the ground. The diode
D24 is connected to be oriented so that a current flows from the
ground toward the transistor Tr24.
[0089] Here, as shown in FIG. 11, the diode D21 may be connected
between the source terminal of the transistor Tr21 and the second
output line O2. The diode D22 may be connected between the source
terminal of the transistor Tr22 and the second output line O2. The
diode D23 may be connected between the transistor Tr23 and the
second output line O2. The diode D24 may be connected between the
transistor Tr24 and the second output line O2.
[0090] Although not shown particularly, an additional circuit may
be provided to avoid an excessive inverse voltage between the gate
and source terminals of the transistors Tr21 to Tr24.
[0091] Then, how an ultrasonic transducer driving circuit 1 of the
present example operates is described. In this ultrasonic
transducer driving circuit 1, a voltage having a waveform that is
shown in FIG. 12 is output from the voltage output type circuit 51.
In FIG. 12, the waveform of an output voltage is simplified and
represented as a sine wave.
[0092] In a state in which the second output line O2 is at a ground
voltage, when an output voltage starts to be supplied from the
voltage output type circuit 51 to the first output line O1 at time
t1, the voltage of this first output line O1 rises and the output
voltage becomes a positive voltage. This produces a current I23
flowing through the transistor Tr23, as shown in FIG. 13, and the
voltage of the second output line O2 rises.
[0093] Then, after the output voltage of the voltage output type
circuit 51 has reached a peak at time t2, when it starts to fall,
the voltage of the second output line O2 becomes smaller than that
of the first output line O1, thereby producing a current I21
flowing through the transistor Tr21 and a current I22 flowing
through the transistor Tr22, as shown in FIG. 14. The current I21
is a current that flows from the second output line O2 toward the
first output line O1. The current I22 is a current that flows from
the second output line O2 toward the ground.
[0094] Then, after the output voltage of the voltage output type
circuit 51 has become equal to the ground voltage at time t3, when
it further falls and becomes a negative voltage, the second output
line O2 becomes lower than the ground voltage, thus resulting in
that the current I21 only flows, but the current I22 does not flow,
as shown FIG. 15.
[0095] Then, after the output voltage of the voltage output type
circuit 51 has become minimum, when it starts to rise, the voltage
of the first output line O1 becomes larger than that of the second
output line O2, thereby producing a current I23 flowing through the
transistor Tr23 and a current I24 flowing through the transistor
Tr24, as shown in FIG. 16. The current I23 is a current that flows
from the first output line O1 toward the second output line O2. The
current I23 is a current that flows from the ground toward the
second output line O2.
[0096] According to the ultrasonic transducer driving circuits 50
of the present example, when the output line O is at a positive
voltage, the current arising from electric charges accumulated in
the ultrasonic transducer 101a flows from the second output line O2
to the ground as the current I22 via the first current discharge
circuit 52 and also flows from the second output line O2 to the
first output line O1 as the current I21. Therefore, power
consumption can be reduced by an amount equivalent to the amount of
the current I22 flowing.
[0097] Likewise, when the output line O is at a negative voltage,
the current arising from electric charges accumulated in the
ultrasonic transducer 101a flows from the ground to the second
output line O2 as the current I24 via the second current discharge
circuit 53 and also flows from the first output line O1 to the
second output line O2 as the current I23. Therefore, power
consumption can be reduced by an amount equivalent to the amount of
the current I24 flowing.
[0098] Next, examples of modification to the second embodiment are
described. To being with, a first modification example is
described. In an ultrasonic transducer driving circuit 50 of the
first modification example, a switch SW1 is provided on a
connection path between the transistors Tr21 and Tr22, that is,
between the gate terminals of the transistors Tr21 and Tr22, as
shown in FIG. 17. Besides, a switch SW2 is provided on a connection
path between the transistors Tr23 and Tr24, that is, between the
gate terminals of the transistors Tr23 and Tr24. As shown in FIG.
18, by turning the switches SW1 and SW2 off, it is possible to make
the transistors Tr22 and Tr24 and the diodes D22 and D24 operate as
a ground clamp circuit that keeps the voltage of the output line O
at the ground voltage level.
[0099] Then, a second modification example is described. In an
ultrasonic transducer driving circuit 50 of the second modification
example, instead of the voltage output type circuit 51, a voltage
output type circuit 51' shown in FIG. 19 is connected to the output
line O. The ultrasonic transducer driving circuit 50 of the second
modification example outputs two levels of voltages as output
voltages.
[0100] The voltage output type circuit 51' includes a positive
voltage output circuit 54 and a negative voltage output circuit 55.
Both the positive voltage output circuit 54 and the negative
voltage output circuit 55 output a voltage to the output line O.
The positive voltage output circuit 54 outputs a positive voltage
to the output line O and the negative voltage output circuit 55
outputs a negative voltage to the output line O.
[0101] The positive voltage output circuit 54 includes a positive
supply voltage +HV, a transistor Tr25, and a diode D25. The diode
D25 is connected between the transistor Tr25 and the output line
O.
[0102] The transistor Tr25 is a p-channel type MOSFET in which the
positive supply voltage +HV is connected to its source terminal and
the diode D2 is connected to its drain terminal To a gate terminal
of the transistor Tr25, a first driver circuit 56 is connected that
outputs a drive signal to turn the transistor Tr25 on/off.
[0103] The negative voltage output circuit 55 includes a negative
supply voltage -HV, a transistor Tr26, and a diode D26. The diode
D26 is connected between the transistor Tr26 and the output line
O.
[0104] The negative voltage output circuit 55 is an n-channel
MOSFET in which the negative supply voltage -HV is connected to its
source terminal and the diode D26 is connected to its drain
terminal To a gate terminal of the transistor Tr26, a second driver
circuit 57 is connected that outputs a drive signal to turn the
transistor Tr26 on/off.
[0105] How the circuit of the second modification example operates
is described. At time t1, as shown in FIG. 12, the transistor Tr25
turns into an ON state. This produces a current I23 flowing through
the transistor Tr23 and the voltage of the output line O rises.
[0106] Then, at time t2, the transistor Tr25 turns into an OFF
state and the transistor Tr26 turns into an ON state. This causes a
decrease in the voltage of the first output line O1, thereby
producing currents I21 and I22 flowing through the transistors Tr21
and Tr22.
[0107] Then, at time t4, the transistor Tr26 turns into an OFF
state and the transistor Tr25 turns into an ON state. This causes
an increase in the voltage of the first output line O1, thereby
producing currents I23, I24 flowing through the transistors Tr23,
Tr24.
Third Embodiment
[0108] Next, a third embodiment is described. Ultrasonic transducer
driving circuits 70 of the present example are provided in the
transmitter unit 1021 of the ultrasonic image display apparatus 100
(see FIG. 1 and FIG. 2), as is the case for the ultrasonic
transducer driving circuits 1 of the first embodiment and the
ultrasonic transducer driving circuits 50 of the second
embodiment.
[0109] As shown in FIG. 20, each of the ultrasonic transducer
driving circuits 70 includes a voltage output type circuit 71 and a
buffer amplifier 72. The voltage output type circuit 71 controls an
output voltage of an output line O and supplies an electrical
current to an output line O for driving the corresponding
ultrasonic transducer 101a. This output line O corresponds to an
output line of the voltage output type circuit 71. The output line
O includes an output line of the ultrasonic transducer driving
circuit 70. The output line O is one example of an embodiment of an
output line.
[0110] Here, a detailed configuration of the voltage output type
circuit 71 is not shown.
[0111] The buffer amplifier 72 is provided along the output line O
of the voltage output type circuit 71. Here, the output line
includes an input line IL to the buffer amplifier 72 and an output
line Ob of the buffer amplifier 72. To the buffer amplifier 72, an
output voltage of the voltage output type circuit 71 is input
through the input line IL.
[0112] The output line Ob of the buffer amplifier 72 is also the
output line of the ultrasonic transducer driving circuit 70.
[0113] The buffer amplifier 72 includes a first push-pull circuit
73 and a second push-pull circuit 74. The first push-pull circuit
73 is configured with transistors Tr31 and Tr32. The second
push-pull circuit 74 is configured with transistors Tr33 and Tr34.
The transistors Tr31 and Tr33 are npn type bipolar transistors. The
transistors Tr32 and Tr34 are pnp type bipolar transistors.
[0114] The first push-pull circuit 73 is one example of an
embodiment of a first push-pull circuit and the second push-pull
circuit 74 is one example of an embodiment of a second push-pull
circuit. Besides, the transistor Tr31 is one example of an
embodiment of a first transistor and the transistor Tr32 is one
example of an embodiment of a second transistor. Further, the
transistor Tr33 is one example of an embodiment of a third
transistor and the transistor Tr34 is one example of an embodiment
of a fourth transistor.
[0115] In the first push-pull circuit 73, emitter terminals of the
transistors Tr31 and Tr32 are connected to each other. In the
second push-pull circuit 74, emitter terminals of the transistors
Tr33 and Tr34 are connected to each other. The output line Ob of
the buffer amplifier 72 is connected between the transistors Tr31
and Tr32, and between the transistors Tr33 and Tr34.
[0116] A positive supply voltage +HV is connected to a collector
terminal of the transistor Tr31. A negative supply voltage -HV is
connected to a collector terminal of the transistor Tr32.
[0117] Collector terminals of the transistors Tr33 and Tr34 are
connected to a ground.
[0118] Between the positive supply voltage +HV and the input line
IL, a current source IS1 and a schottky diode D31 are provided. The
current source IS1 is arranged to the positive supply voltage +HV
and the schottky diode D31 is arranged to the input line IL. A base
terminal of the transistor Tr31 is connected between the current
source IS1 and the schottky diode D31.
[0119] Between the negative supply voltage -HV and the input line
IL, a current source IS2 and a schottky diode D32 are provided. The
current source IS2 is arranged to the negative supply voltage -HV
and the schottky diode D32 is arranged to the input line IL. A base
terminal of the transistor Tr32 is connected between the current
source IS2 and the schottky diode D32.
[0120] Between the positive supply voltage +HV and the input line
IL, a current source IS3 and a diode 33 are also provided in
parallel with the current source IS1 and the schottky diode D31.
The current source IS3 is arranged to the positive supply voltage
+HV and the diode D33 is arranged to the input line IL. A base
terminal of the transistor Tr33 is connected between the current
source IS3 and the diode D33.
[0121] Likewise, between the negative supply voltage -HV and the
input line IL, a current source IS4 and a diode 34 are provided in
parallel with the current source IS2 and the schottky diode D32.
The current source IS3 is arranged to the negative supply voltage
-HV and the diode D34 is arranged to the input line IL. A base
terminal of the transistor Tr34 is connected between the current
source IS4 and the diode D34.
[0122] To the transistors Tr31 to Tr34, a voltage having a
predetermined difference relative to the voltage of the input line
IL, that is, the output voltage of the voltage output type circuit
71 is input. For example, the potential of the base terminal of the
transistor Tr31 is 0.3 V higher than the potential of the input
line IL and the potential of the base terminal of the transistor
Tr33 is 0.7 V higher than the potential of the input line IL. The
potential of the base terminal of the transistor Tr32 is 0.3 V
lower than the potential of the input line IL and the potential of
the base terminal of the transistor Tr34 is 0.7 V lower than the
potential of the input line IL.
[0123] The potential difference between the base terminal of the
transistor Tr33 and the input line IL is larger than the potential
difference between the base terminal of the transistor Tr31 and the
input line IL. The potential difference between the base terminal
of the transistor Tr34 and the input line IL is larger than the
potential difference between the base terminal of the transistor
Tr32 and the input line IL.
[0124] Due to the fact that the potential differences of the base
terminals of the transistors Tr31, Tr33 and the input line IL are
as above, when the output line Ob is at a negative voltage, the
transistor Tr33, of the transistor Tr31 and the transistor Tr33,
turns into an ON state in accordance with an output voltage of the
voltage output type circuit 71, thereby allowing the current
arising from electric charges accumulated in the ultrasonic
transducer 101a to flow from ground to the output line Ob. Further
details will be provided later.
[0125] Due to the fact that the potential differences of the base
terminals of the transistors Tr32, Tr34 and the input line IL are
as above, when the output line Ob is at a positive voltage, the
transistor Tr34, of the transistor Tr32 and the transistor Tr34,
turns into an ON state in accordance with an output voltage of the
voltage output type circuit 71, thereby allowing the current
arising from electric charges accumulated in the ultrasonic
transducer 101a to flow from the output line Ob to ground. Further
details will be provided later.
[0126] Then, how the ultrasonic transducer driving circuit 70
operates is described. A voltage having a waveform that is shown in
FIG. 12, as is the case for the second embodiment, is output from
the voltage output type circuit 71. In a state in which the output
line Ob is at a ground voltage, when an output voltage starts to be
supplied from the voltage output type circuit 71 to the input line
IL at time t1, the voltage of this input line IL rises. With the
rise of the voltage of this input line IL, a base-emitter voltage
of the transistor Tr31 rises and the transistor Tr31 turns into an
ON state. This produces a current I31 flowing through the
transistor Tr31, as shown in FIG. 21, and the voltage of the output
line Ob rises.
[0127] Then, after the output voltage of the voltage output type
circuit 71 has reached a peak at time t2, when it starts to fall,
the transistor Tr31 turns into an OFF state due to a decrease in
its base voltage. As the output voltage of the voltage output type
circuit 71 falls, the base voltages of the transistors 32 and 34
fall. Because the turning of the transistor Tr31 into the OFF state
stops the rise of the voltage of the output line Ob, the falling
base voltages of the transistors Tr32 and Tr34 cause an increase in
the potential difference of base terminal with respect to emitter
terminal in the transistors Tr32 and Tr34.
[0128] Here, as mentioned above, the potential difference between
the base terminal of the transistor Tr34 and the input line IL is
larger than the potential difference between the base terminal of
the transistor Tr32 and the input line IL. Therefore, the
transistor Tr34 turns into an ON state earlier than the transistor
Tr32, thereby producing a current I34 flowing through the
transistor Tr34, as shown in FIG. 22.
[0129] After the transistor Tr34 has turned into the ON state,
until the output voltage of the voltage output type circuit 71
comes to the ground voltage at time t3, the voltage of the input
line IL and the voltage of the output line Ob fall in a state in
which the voltage of the base terminal with respect to the emitter
terminal of the transistor Tr34 is equal to the voltage of the base
terminal of the transistor Tr34 with respect to the input line IL.
After the output voltage of the voltage output type circuit 71 has
come to the ground voltage at time t3, when it further falls, the
voltage of the base terminal with respect to the emitter terminal
of the transistor Tr32 falls and the transistor Tr32 turns into an
ON state, as the voltage of the output line Ob remains at the
ground voltage. This, in consequence, produces a current I32
flowing through the transistor Tr32, as shown in FIG. 23, and the
voltage of the output line Ob falls.
[0130] Then, after the output voltage of the voltage output type
circuit 71 has become minimum, when it starts to rise, the
transistor Tr32 turns into an OFF state due to a rise of its base
voltage. As the output voltage of the voltage output type circuit
71 rises, the base voltages of the transistors Tr31 and Tr33 rise.
Because the turning of the transistor Tr32 into the OFF state stops
the fall of the voltage of the output line Ob, the rising base
voltages of the transistors Tr31 and Tr33 cause an increase in the
potential difference of base terminal with respect to emitter
terminal in the transistors Tr31 and Tr33.
[0131] Here, as mentioned above, the potential difference between
the base terminal of the transistor Tr33 and the input line IL is
larger than the potential difference between the base terminal of
the transistor Tr31 and the input line IL. Therefore, the
transistor Tr33 turns into an ON state earlier than the transistor
Tr31, thereby producing a current I33 flowing through the
transistor Tr33, as shown in FIG. 24.
[0132] After the transistor Tr33 has turned into the ON state,
until the output voltage of the voltage output type circuit 71
comes to the ground voltage at time t4, the voltage of the input
line IL and the voltage of the output line Ob rise in a state in
which the voltage of the base terminal with respect to the emitter
terminal of the transistor Tr33 is equal to the voltage of the base
terminal of the transistor Tr33 with respect to the input line IL.
After the output voltage of the voltage output type circuit 71 has
come to the ground voltage at time t4, when it further rises, the
voltage of the base terminal with respect to the emitter terminal
of the transistor Tr31 rises and the transistor Tr31 turns into an
ON state again, as the voltage of the output line Ob remains at the
ground voltage.
[0133] According to the ultrasonic transducer driving circuit 50 of
the present example, when the output line Ob is at a positive
voltage, the current arising from electric charges accumulated in
the ultrasonic transducer 101a flows from the output line Ob to
ground as the current I34, due to the fact that the transistor Tr34
turns into an ON state. When the output line Ob is at a negative
voltage, the current arising from electric charges accumulated in
the ultrasonic transducer 101a flows from ground to the output line
Ob as the current I33, due to the fact that the transistor Tr33
turns into an ON state.
[0134] Although the present invention has been described in
accordance with the embodiments, it will be obvious that various
modifications to the present invention may be made without changing
the gist of the invention.
* * * * *