JPH02246943A - A/d converter for ultrasonic diagnostic device - Google Patents

Abstract

PURPOSE:To execute an A/D conversion holding the number of effective digits even in the case of an ultrasonic wave receiving signal with a wide dynamic range by amplifying the same receiving signal with different plural amplification rates, A/D-converting the signal in parallel, selecting digital data not to be saturated, and converting the data to data with a large data length. CONSTITUTION:The receiving signal from an ultrasonic transducer 1 is amplified by an amplifier 2 and A/D-converted to an A/D converter 5. At such a time, the amplification rate of the amplifier 2 is made small, and the A/D converter 5 is prevented from being saturated even in the case of an intensive reflected signal from the shallow part of an object. A part of the output of the amplifier 2 is amplified further sixteen-fold by an amplifier 3 and A/D-converted by an A/D converter 6. A part of the output of the amplifier 3 is amplified further sixteen-fold by an amplifier 4 and A/D-converted in the same manner by an A/D converter 7. The digital data obtained respective A/D converters 5, 6 and 7 are inputted to a data converter 8. The data converter 8 prepares converted data with the digital data 9 having the largest number of effective digits among the digital data of the A/D converters 5, 6 and 7 to be unsaturated by means of an electronic digital signal processing, and the converter 8 outputs the data.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an A/D converter for an ultrasonic diagnostic apparatus that is used in an ultrasonic diagnostic apparatus to digitize and process received signals.

BACKGROUND OF THE INVENTION Recently, ultrasonic diagnostic devices have come to be widely used in fields such as medical diagnosis. As for this conventional ultrasound diagnostic device, for example, as described in "Ultrasonic Diagnosis" (edited by the Japan Society of Ultrasound in Medicine, published by Igaku Shoin), Chapter 1, 3-3, "Digital Technology and Image Processing", A configuration is known in which a received signal from a subject is digitized and image processing and signal processing are performed on the digital signal. By processing digital signals in this way, it has become possible to significantly improve image quality compared to conventional ultrasonic diagnostic equipment that processes the entire image using an analog method.

Problems to be Solved by the Invention However, in the conventional example described above, the reception signal from the subject is directly converted from analog to digital (A/D conversion), so the need for a wide dynamic range unique to ultrasound signals requires an order of magnitude difference. The problem is that it is difficult to obtain an effective number of bits unless a large A/D converter is used. This problem will be explained in more detail below.

Among the signals received by the ultrasonic transducer of an ultrasound diagnostic device, the intensity of the reflected signal from the shallow part of the subject reaches several hundred mVpp, but the intensity of the reflected signal from the deep part can be less than 1 mVpp. No, there is a change in reflected signal strength of 60 dB or more. A/D converters are usually IV,...
Since the input level is a full input case, the received signal can hardly be amplified in order to avoid being saturated with the reflected signal from a shallow portion. For this reason, the received signal from deep parts is as small as 1 mpp, so the A/D converter is
In the case of bits, the minimum bit corresponds to about 8 mV, and unless the resolution is less than 1 bit (number of effective digits is 0), no substantial number of effective digits can be obtained.

Due to the above problems, there is a method of compressing the amplitude dynamic range of the received signal using a partial analog logarithm circuit and then applying it to the A/D converter, but this method introduces a lot of distortion to the data and
This becomes a hindrance to later digital signal processing. Therefore, in the past, an A/D converter with a resolution of 12 or 16 bits was required in order to obtain the effective number of digits of the reflected signal from a deep part.
An A/D converter capable of D conversion is expensive and large in size, which poses major practical problems.

The present invention solves the above-mentioned problems of the conventional example, and maintains the number of effective digits even in ultrasonic reception signals with a wide dynamic range by using a general-purpose A/D converter with a practical low bit number. Provides an A/D converter for ultrasonic diagnostic equipment that can perform A/D conversion, and also matches A/D conversion times even with high-frequency received signals to prevent errors from occurring in data. It is an object of the present invention to provide an A/D conversion device for an ultrasonic diagnostic apparatus that can perform the following functions.

Means for Solving the Problems The technical solution of the present invention for achieving the above object is as follows:
a plurality of amplification means for amplifying the same received signal received by the ultrasonic transducer with a plurality of different amplification factors; a plurality of A/D converters that A/D converts the received signal of each amplification factor in parallel; A that is not saturated among these multiple A/D converters
/D converter digital data is electronically selected and the A/D
The data converter converts the data into data having a data length larger than the data length of the converter.

The apparatus also includes a delay means for setting the A/D conversion timings of the plurality of A/D converters to have the same signal delay time.

Therefore, according to the present invention, a received signal with a large amplitude from a shallow area is transmitted to the A/D through an amplifying means with a small amplification factor.
By performing DA/D conversion using a converter, it is possible to obtain digital data that does not saturate, and the received signal with a small amplitude from a deep part is amplified by an amplifying means with a large amplification factor.
By performing F) AID conversion using a /D converter, it is possible to obtain digitized data while maintaining the number of effective digits, and these digital data are electronically reorganized using a data converter to create data. It can be output as long data.

Furthermore, the delay means allows the plurality of A/D converters to perform A/D conversion with the same signal delay time.

EXAMPLES Hereinafter, examples of the present invention will be described with reference to the drawings.

First, a first embodiment of the present invention will be described.

FIG. 1 is a block diagram showing an A/D converter for an ultrasonic diagnostic apparatus in a first embodiment of the present invention.

In FIG. 1, 1 is an ultrasonic transducer;
Ultrasonic pulses are transmitted to the subject and reflected signals are received from the subject. 2 is a first amplifier hv, which amplifies the signal received by the ultrasonic torence deacer 1; 3 is the second
, and a part of the output of the first amplifier 2 is further
Amplify 6 times.

4 is a third amplifier, which further amplifies a part of the output of the second amplifier 3 by 16 times. 5.6.7 are first, second, and third A/D converters, which A/D convert the received signals amplified by the first, second, and third amplifiers 2.3.4, respectively. D-convert. These first, second and third A/D converters 5.6.
7 may be a general-purpose monolithic IC of about 8 bits. 8 is a data converter, and among the first, second, and third A/D converters 5.6.7, the A/D converter 5 is not saturated.
, 6, or 7 A/D conversion data is selected and electronically converted to data with a large data length.

The operation of the above configuration will be described below.

The received signal from the ultrasonic transducer 1 is amplified by the first amplifier 2, and then amplified by the first A/D converter 5! 5A/
D-converted. At this time, the amplification factor of the first amplifier 2 is set so that the first A/D converter 5 is not saturated even with a strong reflected signal from a shallow part of the subject. A part of the output of the first amplifier 2 is further amplified 16 times by the second amplifier 3, and the second A/D converter 6 converts the output into A/D converter 6.
/D converted. A portion of the output of the second amplifier 3 is further amplified 16 times by the third amplifier 4, and A/D converted by the third A/D converter 7 in the same manner as described above.

The digital data obtained by each of the A/D converters 5, 6, and 7 is input to the data converter 8. The data converter 8 generates converted data 9 by electronic digital signal processing using digital data with the largest number of significant digits among the unsaturated digital data of the A/D converters 5, 6, and 7. and output it.

The processing operation of the data converter 8 will be explained in more detail with reference to the processing operation explanatory diagram of FIG.

In FIG. 2, A is 8-bit data indicating the digital data of the third A/D converter 7, B is 8-bit data indicating the digital data of the second A/D converter 6, and C is the 8-bit data indicating the digital data of the first A/D converter 7.
D is 16-bit data representing the converted data 9 of the data converter 8.

The intensity of the reflected signal from a deep part of the subject is weak, and none of the three A/D converters 5.6.7 is saturated. Therefore, since digital data A from the third A/D converter 7 has the largest number of significant digits, bit 0 of this digital data A
-7 correspond to bits O-7 of conversion data D, and O is inserted into bits 8-15 of conversion data D (however, bit 15 is an upper pit and bit 0 is a lower pit).

). When the signal strength increases and the third A/D converter 7 becomes saturated, that is, when all of the digital data A (Pi)O to 7 become 1, the digital data of the second A/D converter 6 becomes 1. Convert bits 0 to 7 of data B bits 4 to 7 of data D
11, and bits O to 3 and 1 of conversion data D
Insert O in 2-15.

If the signal strength further increases and the second A/D converter 6 is also saturated, that is, if all bits 0 to 7 of digital data B become 1, the digital signal of the first A/D converter 5 becomes saturated. Convert bits 0 to 7 of data C bits 8 to 7 of data D
15, and 0 is inserted into bits O to 7 of the conversion data D. Even if the switching is performed as described above, if the amplification factors of the second and third amplifiers 3.4 are set to exactly 16 times, discontinuity of digital data will not occur. In addition, the A/D converter 7
．． Regarding the determination of saturation in step 6, if an overflow signal is output from the A/D converter, this signal may be used.

Through the above operations, the 8-bit general-purpose A/D converter 5.6.
7 makes it possible to obtain 16-bit digital data and greatly expand the dynamic range of the input signal. Also, when switching from the digital data of the third A/D converter 7 to the digital data B of the second A/D converter 6, and when switching from the digital data B of the second A/D converter 6 to the digital data B of the second A/D converter 6, Digital data C of A/D converter 5 of 1
Although the number of effective digits decreases when switching to , at least 4 effective digits can be obtained even then, which is sufficient for ultrasound image data.

Note that in the first embodiment, three A/D converters 5.
Although the case where 6.7 is operated in parallel has been described, if the dynamic range of the input signal is to be further expanded, the number of amplifiers and A/D converters may be increased. Also, the second
If the amplification factor of the third amplifier 3.4 is set to a double number other than 16 times, the number of digits of digital data to be moved when switching each A/D converter 7.6.5 will change. , can be set according to the final number of significant digits required. Further, in the above embodiment, the case where an 8-bit A/D converter 5.6.7 is used has been explained, but it is of course possible to use a converter other than 8-bit.

Next, a second embodiment of the present invention will be described.

FIG. 3 is a block diagram showing an A/D converter for an ultrasonic diagnostic apparatus in a second embodiment of the present invention.

In this embodiment, the same parts as in the first embodiment shown in FIG. 1 are denoted by the same reference numerals, and the explanation thereof will be omitted, and the different configuration will be explained. In this embodiment, a first delay device IO is inserted between the first amplifier 2 and the first A/D converter 5, as shown in FIG. A second delay device 11 is inserted between the A/D converters 6.

The operation of the above configuration will be described below.

In the first embodiment shown in FIG. 1, the second amplifier 3,
Since the third amplifier 4 has a finite signal propagation time, it causes a signal delay. Therefore, when the frequency of the input signal is high, errors occur in the digital data because the time relationships of A/D conversion in each A/D converter 5, 6, and 7 are different. To prevent this, in this embodiment, the sending of the analog signal is delayed by the first and second delay devices 10 and 11 in order to match the effective A/D conversion time. That is, the first delay device 10 is the total delay time of the second amplifier 3 and the third amplifier 4, and the delay time from the first amplifier 2 to the first A/D converter 5.
The second delay device 11 delays the sending of the output signal to the second amplifier 3 for the same time as the delay time of the third amplifier 4.
The transmission of the output signal to the second A/D converter 6 is delayed.

With such a configuration, even high-frequency input signals have the same conversion time, and it is possible to prevent errors from occurring in the data.

Note that instead of delaying the output of the analog signal by the delay device 10.11 as in the second embodiment, the trigger signal of the conversion trigger input signal of the A/D converter 5.6.7 is It is also possible to delay the time corresponding to the delay time of .

In short, the analog signal or digital trigger signal may be delayed so that the effective A/D conversion time is the same in each A/D converter 5.6.7.

Furthermore, in both the first and second embodiments, multiple signals with different amplification factors may be created by not using all of the multiple amplifiers with different amplification factors, but using some resistor attenuators etc. to generate the signals. Good things are natural.

Effects of the Invention As described above, according to the present invention, a received signal with a large amplitude from a shallow part is amplified by an amplifying means with a small amplification factor.
Digital data that does not saturate can be obtained by A/D conversion using a /D converter, and small amplitude received signals from deep parts are converted to A/D through an amplifier with a large amplification factor.
By performing F)AID conversion using a /D converter, it is possible to obtain digitized data while maintaining the number of effective digits, and these digital data can be reorganized into stain reservations using a data converter to convert large data lengths. It can be output as data. Therefore, it is possible to digitize a received signal with a wide dynamic range using a general-purpose A/D converter while maintaining the number of effective digits.

In addition, the delay means allows the plurality of A/D converters to perform A/D conversion with the same signal delay time, making the A/D conversion time the same even for high-frequency received signals, causing errors in data. can be prevented.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an A/D converter for an ultrasonic diagnostic apparatus according to a first embodiment of the present invention, and FIG.
FIG. 3 is a block diagram showing an A/D converter for an ultrasonic diagnostic apparatus in a second embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Ultrasonic transducer, 2.3.4... Amplifier, 5.6.7... A/D converter, 8... Data converter, 1O111... Delay device. Name of agent: Patent attorney Shigetaka Awano and one other person

Claims (2)

[Claims] (1) a plurality of amplification means for amplifying the same received signal received by the ultrasonic transducer at a plurality of different amplification factors;
Multiple A/D converters that A/D convert received signals of each amplification factor in parallel.
electronically selecting digital data of a D converter and an A/D converter that is not saturated among the plurality of A/D converters;
A for ultrasonic diagnostic equipment equipped with a data converter that converts data into data with a data length larger than the data length of the A/D converter
/D conversion device. (2) The A/D converter for an ultrasonic diagnostic apparatus according to claim 1, further comprising a delay means for setting A/D conversion timings of the plurality of A/D converters to have the same signal delay time.