JPH03114449A - Digital rf type ultrasonic diagnostic apparatus - Google Patents

Abstract

PURPOSE:To simplify constitution by providing one decimation filter behind a digital beam former without providing decimation filters at every channels. CONSTITUTION:A digital RF type ultrasonic diagnostic apparatus has a primary DELTA-SIGMA tracker 11 to which the signals of respective channels are inputted, a digital beam former 30 respectively delaying and adding the outputs of the primary DELTA-SIGMA tracker 11 and one decimation filter 31 converting the output signal of the digital beam former 30 to a digital signal. By providing one decimation filter 31 behind the digital beam former 30 without providing decimation filters at every channels, constitution is simplified. When an analogue filter is used as the decimation filter 31, the analogue signal of the echo of the sound ray synthesized with the output thereof is obtained.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a digital RF type fez-array type extremely short range sonar, particularly to an ultrasonic diagnostic device having a function as a medical ultrasonic imager. It relates to wave reception and beamforming means.

[Prior Art] FIG. 6 is a block diagram showing a circuit configuration around a beam former of a conventional digital RF type ultrasonic diagnostic apparatus. In the figure, (10) is an A/D converter. This A/D converter (10) is composed of a Δ-Σ tracker (11) and a decimation filter (16). The Δ-Σ tracker (11) is composed of an adder (12), a filter (13), an amplifier (14), and a filter (15). (20) is a digital beam former. In addition, in this figure, A for one channel is
Only the /D converter (10) is shown, and other channels are omitted.

A conventional digital RF type ultrasonic diagnostic apparatus is configured as described above, and the RF signal El(k
) is converted into a binary digital signal string through a Δ-Σ tracker (11) and a decimation filter (16) and input to a digital beamformer (20), where it is subjected to signal processing and transmitted to the subsequent device ( (not shown).

[Problems to be Solved by the Invention] In the conventional digital RF type ultrasonic diagnostic apparatus as described above, it is sufficient that the word rate of the data words of each channel satisfies the Nyquist condition. It was sufficient to sample the signal at a sampling rate of 4FO. However, A/
Whatever the D-converter approach, the data word handling must be parallel and the digital beamformer (2
0) requires a corresponding number of input lines and also requires timing accuracy, making the device complicated.

The present invention was made to solve these problems, and an object of the present invention is to provide a digital RF type ultrasonic diagnostic apparatus with a simpler configuration.

[Means for Solving the Problems] A digital RF type ultrasonic diagnostic apparatus according to the present invention includes a first-order Δ-Σ tracker (or pulse width modulator) into which signals of each channel are input, and a first-order Δ-Σ tracker (or pulse width modulator). The output of the Δ-Σ tracker (or pulse width modulator) is delayed and
It has a digital beamformer for adding and one decimation filter for converting the output signal of the digital beamformer into a digital signal.

Further, the digital RF type ultrasonic diagnostic apparatus according to the present invention uses a second-order or higher-order Δ-Σ tracker instead of the first-order Δ-Σ tracker, and uses , insert a linearizer for each channel.

Further, in an example of the digital RF type ultrasonic diagnostic apparatus according to the present invention, an analog filter is used as the decimation filter.

[Function] In this invention, one decimation filter is provided after the digital beamformer without providing a decimation filter for each channel, so the configuration is simplified.

Furthermore, in this invention, since a linearizer is inserted for each channel, it is possible to reduce the chip rate.

Further, in the present invention, since an analog filter is used instead of a decimation filter, an analog signal of echoes of sound rays synthesized with the output thereof can be obtained.

[Embodiment] FIG. 1 is a diagram showing a circuit configuration around a beam former of a digital RF type ultrasonic diagnostic apparatus according to an embodiment of the present invention. In the figure, (11) to (15) are the sixth
This is exactly the same as the conventional device shown in the figure. (3
0) is a digital beam former according to this embodiment. (31) is a common decimation filter.

Figure 2 shows the delay and delay of the digital beamformer (30).
FIG. 2 is a block diagram showing the configuration of an addition section. In the figure,
(40-1), (40-2), (40-3),
... (40-84) are variable-length shift registers to which the comparator outputs of the Δ-Σ trackers of each channel are input, and one long shift register for each channel (for example, 10 μSeC), provided that the bit rate is Δ -High speed that is sufficient to match that of the Σ tracker (e.g. ≦ton
s). (41) is an adder that adds the outputs of this fully variable length shift register. In this embodiment, a first-order Δ-Σ tracker is used, and since each channel has one bit, it is constituted by an adder having parallel input terminals for the number of channels.

In the digital RF type ultrasonic diagnostic apparatus configured as described above, the system clock φ is 100 to 200 times or more than the center frequency fo, and the Δ-Σ tracker of all channels is It operates synchronously with that system clock. Then, the comparator output (binary signal) of the Δ-Σ tracker of each channel that comes out for each clock is directly controlled by the digital beamformer (30) without passing it through a decimation filter individually as in the conventional case. Long shift register (40-1), (
40-2).

(40-3), ... (40-64) at the same timing.

And variable length shift register (40-1), (4
0-2).

By changing the length (number of stages) of (40-3), ... (40-84), the delay distribution necessary for beamforming is realized, and the output of the delay distribution is added by an adder (41).
The resulting digital composite output is output to a decimation filter (31) common to all channels, and a signal forming a digital beamformer is output from this decimation filter (31).

Figure 3 shows the delay and delay of the digital beamformer (30).
FIG. 7 is a block diagram showing another example of the configuration of the addition section, and this embodiment employs a partial addition method.

In the figure, (42) to (45) are adders each having parallel input terminals for 15 channels. (46) is an adder that adds the outputs of adders (42) to (45).

In this embodiment, the signals of each channel are sent to variable length shift registers (40-1) to (40-64), and the adder (42) is sent to variable length shift registers (40-1) to (40-64).
-15) to output a 4-bit signal, and the other adders (43), (44), and (45) add the outputs of the variable length shift registers and output the same. The adder (4B) adds the outputs of the adders (42) to (45) and sends an output signal consisting of, for example, 6-bit data to the decimation filter (31).

Figure 4 shows the delay and delay of the digital beamformer (30).
FIG. 7 is a block diagram showing another example of the configuration of the adder section, in which variable delay registers are distributed between the adders to reduce the total length of the required shift registers. In the figure,
(47), (48), (49), and (50) are adders, respectively. (51-1) ~ (51-7) C
(hereinafter referred to as (51)) is a variable length shift register,
There are 57 more similar ones, but they are not shown.

(52) are three variable length shift registers provided corresponding to the 3-bit signal line from the adder (47);
There are seven more similar ones, but they are not shown. (5
3) and (54) are adders (48) and (49), respectively.
) are provided corresponding to the 5-bit signal lines from the 5-bit signal line.

In this embodiment, the signals of each channel delayed by the variable length shift register (51) are added by the adder (47), and the output thereof is input to the variable shift register (52), where the signal is delayed and then added by the adder (47). 48), (49) are added,
Its output is a variable shift register (53), (54)
are delayed respectively. This delay result is sent to the adder (50)
The addition result consists of a 6-bit signal structure and is sent to a decimation filter (31).

By the way, in the above embodiment, an example was shown in which a Δ-Σ tracker was used as a subsystem of an A/D converter, but the S/N
It is conceivable to use a method with a variable step size (adaptive delta modulation (ADM) method) to improve this. However, at that time, the output of the Δ-Σ tracker system is
Since the value signal cannot be returned to the original analog signal even if it is directly applied to an integrating circuit or a low-pass filter, corresponding signal processing is required.

FIG. 6 is a circuit diagram that takes such signal processing into consideration.

In the figure, (60) is a beam riser, which is an F in which a shift register (61) and a state change table are stored.
It is composed of ROM (62). This shift register (61) has a high-order Δ-
A binary signal from the Σ tracker is input, and this signal is
” or a pattern of consecutive “0”s, press F R
The corresponding addition value (step size) is given by OM (82). In this way, the invention can be applied at slower clock rates and over a wider dynamic range.

Also, in that the output pit stream can be converted to the original signal by passing it through an integrating circuit or a low-pass filter,
In addition to the Δ-Σ tracker, there is a pulse width modulator, which
Exactly the same operation can be obtained by replacing the tracker with a pulse width modulator.

Furthermore, if an analog filter is used as the decimation filter (31) in the embodiment shown in FIG. 1, an analog signal of echoes of the sound rays synthesized with its output can be obtained.

[Effects of the Invention] As described above, according to the present invention, one decimation filter is provided after the digital beamformer instead of providing a decimation filter for each channel, which simplifies the configuration. . Furthermore, when a Δ-Σ tracker is used, all the features of the Δ-Σ oversampling type A/D conversion can be utilized. When one analog filter is provided as a decimation filter, an analog signal of synthesized sound ray echoes can be obtained by using only one analog filter.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the circuit configuration around the beamformer of a digital RF type ultrasonic diagnostic apparatus according to an embodiment of the present invention, and FIGS. 2 to 4 show delay and addition of the digital beamformer, respectively. FIG. 5 is a block diagram showing an example of a configuration of a linearizer, and FIG. 6 is a diagram showing a circuit configuration around a beam former of a conventional digital RF ultrasonic diagnostic apparatus. . In the figure, (11) is a Δ-Σ tracker, (30) is a digital beam former, and (31) is a decimation filter.

Claims (4)

[Claims] (1) First-order Δ− that each channel signal inputs
a digital beamformer that delays and adds the outputs of the Σ tracker and the first-order Δ-Σ tracker, respectively;
A digital RF type ultrasonic diagnostic apparatus comprising one decimation filter that converts the output signal of the digital beamformer into a digital signal and outputs the digital signal. (2) Instead of a first-order Δ-Σ tracker, a second-order or higher-order Δ-Σ tracker is used, and a linearizer is inserted for each channel at the position before addition of the digital beamformer. The digital RF type ultrasonic diagnostic apparatus according to claim 1. (3) The digital RF type ultrasonic diagnostic apparatus according to claim 1, characterized in that a pulse width modulator is used in place of the first-order Δ-Σ tracker. (4) The digital RF type ultrasonic diagnostic apparatus according to claim 1 or 2, characterized in that an analog filter is used as the decimation filter.