JP5558914B2 - Transmission circuit of ultrasonic diagnostic equipment - Google Patents

Description

  The present invention relates to a transmission circuit of an ultrasonic diagnostic apparatus, and more particularly to a technique for applying a bias to a drive circuit that amplifies an original transmission signal.

  The transmission circuit of the ultrasonic diagnostic apparatus drives the vibration element by amplifying the power of the transmission signal by an amplification circuit (drive circuit) and supplying the amplified signal to the vibration element. Conventionally, as such an amplifier circuit for power amplification, a circuit capable of faithfully linearly amplifying an arbitrary waveform such as a pulse wave, a sine wave, and a Gaussian wave has been proposed (see Patent Documents 1 and 2).

  In order to operate the amplifier circuit at a desired operating point, a bias is applied to the amplifier circuit. In the case of an ultrasonic diagnostic apparatus, since a large number of vibration elements of several hundred channels are driven, a large number of amplifier circuits are provided, so power consumption and heat generation due to bias current cannot be ignored.

  Thus, for example, in the transmission circuit described in Patent Document 1, the power consumption during non-transmission is reduced by applying a bias to the amplifier circuit only during signal transmission. That is, the transmission circuit includes a bias on / off circuit for each amplifier circuit and a circuit that generates a control signal for controlling on / off of each of the on / off circuits according to a signal transmission period.

  The transmission circuit disclosed in Patent Document 2 does not require such a control signal, but if the bias current consumed by the amplifier circuit during non-transmission is reduced, output amplitude attenuation called a droop phenomenon occurs. There is a problem.

Japanese Patent No. 3857676 JP 2008-188321 A

  In the present invention, the bias application to the drive circuit (amplifier circuit) that amplifies the original transmission signal is limited to the signal transmission period of the original transmission signal without using a bias on / off circuit or a signal generation circuit for on / off control. It aims to be realized.

  In one aspect, the transmission circuit of the ultrasonic diagnostic apparatus according to the present invention includes a drive circuit that generates a drive signal for the ultrasonic transducer by amplifying the original transmission signal, and a waveform of the original transmission signal. Supply means for supplying bias added waveform data, which is a result of adding a bias to be applied to the drive circuit for amplification of the original transmission signal to the original transmission signal waveform data to be represented, and supplied from the supply means A digital / analog conversion circuit that converts the bias-added waveform data into an analog signal, and the drive circuit amplifies the analog signal output from the digital / analog conversion circuit, thereby Generating the drive signal for.

  In one aspect, the bias-added waveform data is waveform data obtained by adding the bias with the same polarity as the signal polarity of the corresponding section to the signal portion of the section of each signal polarity of the original transmission signal.

  In another aspect, the supply means includes first generation means for generating the original transmission signal waveform data, second generation means for generating bias waveform data representing the waveform of the bias to be applied to the drive circuit, and An adder that adds the original transmission signal waveform data generated by the first generation means and the bias waveform data generated by the second generation means to generate the bias-added waveform data; and The digital / analog conversion circuit converts the bias-added waveform data output from the adder into an analog signal.

  In still another aspect, the supply means generates first original transmission signal waveform data, and the original transmission signal waveform data generated by the first generation means is to be supplied to the drive circuit. A waveform processing circuit that generates the bias-added waveform data by processing according to a bias level, and the digital-to-analog converter circuit outputs the bias-added waveform data output from the waveform processing circuit. Convert to analog signal.

  In still another aspect, the supply means is a result of adding a bias to be applied to the drive circuit for amplification of the original transmission signal to the original transmission signal waveform data representing the waveform of the original transmission signal. Storage means for storing bias-added waveform data, and the digital-to-analog converter circuit converts the bias-added waveform data read from the storage means into an analog signal.

  ADVANTAGE OF THE INVENTION According to this invention, the circuit structure for the application of the bias with respect to the drive circuit in the transmission circuit of an ultrasonic diagnosing device can be simplified.

It is a functional block diagram which shows an example of the transmission circuit of the ultrasonic diagnosing device of embodiment. It is a figure which shows an example of the waveform of an original transmission signal. FIG. 3 is a diagram illustrating an example of a bias waveform corresponding to the original transmission signal illustrated in FIG. 2. FIG. 4 is a diagram illustrating an example of a bias added waveform obtained by adding the bias of FIG. 3 to the original transmission signal of FIG. It is a figure which shows an example of a drive circuit (amplifier circuit). It is a functional block diagram which shows another example of the transmission circuit of an ultrasonic diagnosing device. It is a functional block diagram which shows another example of the transmission circuit of an ultrasonic diagnosing device.

  FIG. 1 shows an example of a transmission circuit of the ultrasonic diagnostic apparatus according to the embodiment. In this example, in the original transmission waveform memory 10a, the vibration elements 20-1 to 20-n (n is the number of vibration elements included in the ultrasonic probe, that is, the number of channels) (hereinafter collectively referred to as the vibration element 20). The original transmission signal waveform data representing the waveform of the original transmission signal which is a drive signal for driving the signal is stored.

  FIG. 2 shows an example of the original transmission signal waveform 100 stored in the original transmission waveform memory 10a. This shows a waveform of two periods of sine waves having a certain amplitude and period. For example, by continuously repeating and outputting the waveform data for two cycles, the vibration element 20 can be driven by a CW (continuous wave) sine wave having the amplitude and cycle. Such a continuous wave can be used for the continuous wave Doppler method, for example.

  The original transmission waveform memory 10a may store a plurality of different original transmission signal waveform data. For example, the original transmission signal waveform data of various waveform types such as a pulse wave, a sine wave, and a Gaussian wave may be stored in the original transmission waveform memory 10a. Further, a plurality of original transmission signal waveform data having different amplitudes and / or frequencies may be stored for the same waveform type (types such as pulse wave, sine wave, and Gaussian wave). In addition, for one waveform type, only one waveform data whose amplitude and / or period can be changed parametrically is stored in the original transmission waveform memory 10a, and the amplitude and / or period or both of the waveform data is stored. It may be configured to generate desired waveform data by designating.

  Further, the waveform data stored in the original transmission waveform memory 10a may be data in which voltage levels at respective times are arranged in time series, and functions and waveform generation rules for defining such voltage waveforms parametrically. Or the like. In the latter case, a time-series voltage level sequence representing the original transmission signal is shown according to the stored original transmission signal waveform data (function, etc.) and parameters (for example, amplitude and period) specified by the user. A circuit for generating digital data may be provided between the original transmission waveform memory 10 a and the adder 12.

  The original transmission signal waveform data to be output from the original transmission waveform memory 10a is determined by the controller 30 based on the user input (for example, mode selection) to the operation unit of the ultrasonic diagnostic apparatus or the type of the ultrasonic probe attached. select.

  Bias waveform data is stored in the bias waveform memory 10b. The bias waveform is a waveform representing a time change of a bias to be applied to the drive circuit 18 when the drive (amplification) circuits 18-1 to 18-n (hereinafter collectively referred to as the drive circuit 18) amplify the original transmission signal. It is. The bias is a DC voltage applied to use the drive circuit 18 in a desired linear amplification region (in other words, defining an operating point of the drive circuit 18).

  FIG. 3 shows an example of the bias waveform 110 corresponding to the original transmission signal waveform 100 of FIG. The bias waveform 110 in FIG. 3 is a signal having a predetermined bias voltage level that has the same polarity as the signal polarity in each range of each signal polarity (positive or negative polarity) of the original transmission signal waveform 100. It is a waveform. That is, when the bias voltage level is BL (positive value), the bias waveform has a level of + BL when the original transmission signal waveform 100 is in the positive range and −BL when the original transmission signal waveform 100 is in the negative range. Bias waveform data representing such a bias waveform 110 is stored in the bias waveform memory 10b.

  Although the original transmission signal waveform in FIG. 2 is a sine wave, even if it is another waveform such as a pulse wave or a Gaussian wave, the bias waveform is similarly + BL and negative in the range where the original transmission signal waveform is positive. A waveform having a level of -BL in the range may be used.

  When a plurality of original transmission signal waveform data is stored in the original transmission waveform memory 10a, the bias waveform data corresponding to each original transmission signal waveform data may be stored in the bias waveform memory 10b. Thus, instead of preparing bias waveform data for each original transmission signal waveform data, only one bias waveform data whose bias voltage level and / or period can be changed parametrically is stored in the bias waveform memory 10b. The configuration may be such that desired bias waveform data is generated by designating a bias voltage level and / or a period for the waveform data. Also, the waveform data of the bias waveform may be data in which the voltage levels at each time are arranged in time series like the original transmission signal, and functions and waveform generation rules for defining such voltage waveforms parametrically. Or the like. In the latter case, digital data indicating a series of time-series voltage levels representing a bias waveform in accordance with stored bias waveform data (function, etc.) and parameters (for example, bias voltage level and period) specified by the user. May be provided between the bias waveform memory 10 b and the adder 12.

  The controller 30 selects the original transmission signal waveform to be output from the original transmission waveform memory 10a, and at the same time, selects the bias waveform corresponding to the original transmission signal waveform and outputs it from the bias waveform memory 10b. When the vibration element 20 is driven by a continuous wave, for example, the unit waveform data of a sine wave is repeatedly output from the original transmission waveform memory 10a, and the bias waveform data corresponding to the unit waveform data is repeatedly output from the bias waveform memory 10b. Let Further, when the vibration element 20 is driven with a pulse wave, the waveform data of the pulse wave and the corresponding bias waveform data from the original transmission waveform memory 10a and the bias waveform memory 10b are synchronized with the timing of transmitting the pulse wave. Can be output.

  The adder 12 adds the original transmission signal waveform data and the bias waveform data read out in synchronization with each other from the original transmission waveform memory 10a and the bias waveform memory 10b in accordance with an instruction from the controller 30. That is, the adder 12 adds the signal level values at the same time of the synchronized original transmission signal waveform data and bias waveform data. By this addition, bias added waveform data obtained by adding the original transmission signal waveform data and the bias waveform data is generated.

  FIG. 4 shows an example of a bias-added waveform 120 that is the result of adding the original transmission signal waveform 100 of FIG. 2 and the bias waveform 110 of FIG. As described above, the bias-added waveform is a waveform in which the waveform portion of each of the positive and negative polarity ranges of the original transmission signal waveform is raised in the direction of the polarity of the corresponding range by the bias voltage level. .

  In the example of FIG. 1, the bias-added waveform data output from the adder 12 is input to the delay circuits 14-1 to 14-n of the respective channels. Each delay circuit 14-1 to 14-n delays the input bias-added waveform data by a delay amount corresponding to the channel of the delay circuit itself. The bias-added waveform data delayed by the respective delay circuits 14-1 to 14-n are D / A (digital / analog) conversion circuits 16-1 to 16-n (hereinafter, collectively referred to as D / A conversion circuit 16). Are converted into analog signals. This time change of the voltage of the analog signal corresponds to the waveform represented by the bias added waveform data.

  The analog signals output from the D / A conversion circuits 16-1 to 16-n are power-amplified by the drive (amplification) circuits 18-1 to 18-n, respectively, and are supplied to the vibration elements 20-1 to 20-n. Supplied. The drive circuit 18 is used in an area where linear amplification is possible by a digital bias application method described later in order to amplify an arbitrary waveform inputted as faithfully as possible.

  FIG. 5 shows an example of a specific circuit configuration of the drive circuit 18. This circuit configuration is a push-pull circuit configuration for amplifying positive and negative input signals by MOSFETs Q1 and Q2, respectively. An analog signal output from the D / A conversion circuit 16 is input to the input terminal of the circuit of FIG. 5, and the signal output from the output terminal of the circuit of FIG. Such a push-pull amplifier circuit configuration is well known as the configuration of the amplifier circuit of the transmission circuit of the ultrasonic diagnostic apparatus, and therefore detailed description thereof is omitted (a similar circuit is shown in Patent Document 2). Also, see Patent Document 1).

  In the circuit configuration of FIG. 5, due to the input / output characteristics of the MOSFETs Q1 and Q2, even if the original transmission waveform is input as it is, crossover distortion or the like occurs. In order to eliminate this distortion, a bias voltage is conventionally applied to the MOSFETs Q1 and Q2. In particular, in the circuit of Patent Document 1, a control circuit for applying a bias only during a period in which a signal is actually transmitted ( By providing a bias on / off circuit, a signal generation circuit for on / off control, and the like, low power consumption and reduced heat generation have been achieved.

  On the other hand, the transmission circuit of FIG. 1 generates data (bias added waveform data) representing the signal waveform after bias application by adding the digital data of the bias waveform to the digital data of the original transmission signal waveform. To do. That is, in this example, the bias is applied digitally. The bias-added waveform data is converted into an analog signal and supplied to the drive circuit 18, so that the MOSFETs Q1 and Q2 in the drive circuit 18 are biased in a section where the original transmission signal waveform has positive and negative polarities. The original transmission signal waveform can be amplified at an appropriate operating point. As a result, the output of the drive circuit 18 has a waveform close to the original transmission signal waveform without crossover distortion or the like (or reduced).

  As described above, the transmission circuit of FIG. 1 can be in a state in which a bias is applied only during a period in which the original transmission signal exists (that is, a period of positive or negative polarity). And reduction of heat generation can be achieved.

  In the transmission circuit of FIG. 1, since bias is added to the original transmission signal waveform at the stage of digital data, it is only necessary to provide a common bias waveform memory 10b and an adder 12 for many channels. Therefore, the circuit configuration can be made simpler than the conventional configuration in which a bias on / off circuit and a signal generation circuit for on / off control are provided for each individual channel.

  1 is a digital waveform that generates digital waveform data indicating a time-series voltage level sequence representing the original transmission signal from data such as a function that defines the original transmission signal waveform parametrically and waveform generation rules. When the generation circuit is provided, the digital addition of the original transmission signal waveform and the bias waveform may be performed using a logic circuit (for example, an adder) in the digital waveform generation circuit. Some transmission circuits of conventional ultrasonic diagnostic apparatuses have such a digital waveform generation circuit. In such a transmission circuit, an adder 12 is used to realize the circuit configuration of this embodiment. There is no need to add.

  Next, another configuration example of the transmission circuit will be described with reference to FIG.

  The circuit configuration of FIG. 6 includes a bias level memory 10 c and a waveform processing circuit 13 instead of the bias waveform memory 10 b and the adder 12 in the example of FIG. Other elements may be the same as in the example of FIG.

  The bias level memory 10c stores a bias voltage level BL (positive value) to be applied to the drive circuit 18. The waveform processing circuit 13 performs waveform processing for reflecting the bias of the level BL stored in the bias level memory 10c on the original transmission signal waveform data supplied from the original transmission waveform memory 10a. In this waveform processing, BL is added to the signal level of the original transmission signal waveform in a section where the original transmission signal waveform has a positive polarity. Further, in a section where the original transmission signal waveform has a negative polarity, -BL is added to the signal level of the original transmission signal waveform.

  6 is a digital waveform generation circuit that generates digital data indicating a time-series voltage level sequence representing an original transmission signal from data such as a function for defining the original transmission signal waveform parametrically and a waveform generation rule. If provided, the function of the waveform processing circuit 13 can also be realized by using a logic circuit in the digital waveform generation circuit. In the example of FIG. 6, the same effect as that of the example of FIG. 1 can be obtained.

  Next, still another configuration example of the transmission circuit will be described with reference to FIG.

  The circuit configuration of FIG. 7 includes a waveform memory 10d instead of the bias waveform memory 10b and the adder 12 in the example of FIG. Other elements may be the same as in the example of FIG.

  The waveform memory 10d stores bias added waveform data obtained by digitally adding bias waveform data to the original transmission signal waveform data. When there are a plurality of original transmission signal waveform data, bias-added waveform data is created in advance according to each original transmission signal waveform data and stored in the waveform memory 10d. The controller 30 causes the waveform memory 10d to output the bias-added waveform data corresponding to the original transmission signal waveform indicated by the instruction from the user. The output bias added waveform data is supplied to each delay circuit 14. In the example of FIG. 7, the same effect as that of the example of FIG. 1 can be obtained.

  Each example of the transmission circuit described above can be used to generate transducer drive signals for various diagnostic modes such as continuous wave Doppler method, pulse Doppler method, blood flow color imaging, B mode, A mode, and M mode. (However, it does not necessarily need to be available for all of these).

  The example of the transmission circuit according to the embodiment described above is merely an example, and various other modifications can be considered.

  For example, in the above-described example, a common bias is applied to all channels (vibration elements), but a bias is individually applied to each channel (for example, in accordance with the characteristics of the drive circuit 18 of the channel). You can also Taking the configuration of FIG. 1 as an example, in this modification, for example, an adder 12 may be provided for each channel (or an adder of a digital waveform generation circuit provided individually for each channel may be used. ). Then, the common original transmission signal waveform data and the bias waveform data specific to the channel are supplied and added to the adder for each channel. Information (such as bias waveform data or bias voltage level) that defines a bias specific to each channel may be stored in the bias waveform memory 10b or the bias level memory 10c. In the example of FIG. 7, the bias-added waveform data for each channel may be stored in the waveform memory 10d.

  The bias voltage level may be changed according to the mode of the ultrasonic diagnostic apparatus. For example, the bias voltage level is changed between a continuous wave and a pulse wave. In this case, the bias waveform data and the bias voltage level are stored for each mode in the bias waveform memory 10b and the bias level memory 10c, and the controller 30 selects a bias corresponding to the mode.

  1, 6 and 7 are examples in which one delay circuit 14, one D / A conversion circuit 16 and one drive circuit 18 are provided for each channel, this is merely an example. Even when one or more of the delay circuit 14, the D / A conversion circuit 16, and the drive circuit 18 are shared by a plurality of channels, the method of this embodiment can be applied.

  In the above example, the drive circuit 18 is exemplified as a type that can amplify both positive and negative polarities. However, even when a drive circuit that amplifies only positive or negative polarity is used, The method is applicable.

  10a original transmission waveform memory, 10b bias waveform memory, 12 adder, 14-1 to 14-n delay circuit, 16-1 to 16-n D / A conversion circuit, 18-1 to 18-n drive circuit, 20- 1-20-n Vibration element.

Claims (5)

A drive circuit that generates a drive signal for the ultrasonic transducer by amplifying the original transmission signal;
Supply means for supplying bias added waveform data, which is a result of adding a bias to be applied to the drive circuit for amplification of the original transmission signal to the original transmission signal waveform data representing the waveform of the original transmission signal; ,
A digital-to-analog conversion circuit for converting the bias-added waveform data supplied from the supply means into an analog signal;
With
The transmission circuit of an ultrasonic diagnostic apparatus, wherein the drive circuit generates the drive signal for the ultrasonic transducer by amplifying an analog signal output from the digital / analog conversion circuit. A transmission circuit of the ultrasonic diagnostic apparatus according to claim 1,
The bias-added waveform data is waveform data obtained by adding the bias with the same polarity as the signal polarity of the section to the signal portion of the section of each signal polarity of the original transmission signal.
A transmission circuit for an ultrasonic diagnostic apparatus. The transmission circuit of the ultrasonic diagnostic apparatus according to claim 1 or 2,
The supply means includes
First generation means for generating the original transmission signal waveform data;
Second generation means for generating bias waveform data representing the waveform of the bias to be applied to the drive circuit;
An adder that adds the original transmission signal waveform data generated by the first generation means and the bias waveform data generated by the second generation means to generate the bias-added waveform data;
With
The transmission circuit of an ultrasonic diagnostic apparatus, wherein the digital / analog conversion circuit converts the bias-added waveform data output from the adder into an analog signal. The transmission circuit of the ultrasonic diagnostic apparatus according to claim 1 or 2,
The supply means includes
First generation means for generating the original transmission signal waveform data;
A waveform processing circuit for generating the bias-added waveform data by processing the original transmission signal waveform data generated by the first generation means according to the level of the bias to be applied to the drive circuit;
With
The transmission circuit of the ultrasonic diagnostic apparatus, wherein the digital / analog conversion circuit converts the bias-added waveform data output from the waveform processing circuit into an analog signal. The transmission circuit of the ultrasonic diagnostic apparatus according to claim 1 or 2,
The supply means includes
Storage means for storing bias-added waveform data that is a result of adding a bias to be applied to the drive circuit for amplification of the original transmission signal to the original transmission signal waveform data representing the waveform of the original transmission signal ,
With
The transmission circuit of an ultrasonic diagnostic apparatus, wherein the digital / analog conversion circuit converts the bias-added waveform data read from the storage means into an analog signal.

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