GB1564777A

GB1564777A - Ultrasonic imaging apparatus

Info

Publication number: GB1564777A
Application number: GB2751777A
Authority: GB
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 1976-07-02
Filing date: 1977-06-30
Publication date: 1980-04-16
Also published as: JPS535884A; DE2629895B2; FR2356953A1; DE2629895C3; DE2629895A1; NL7703388A; FR2356953B1

Description

(54) ULTRASONIC IMAGING APPARATUS (71) We, SIEMENS AKTIENGESELL SCHAFT, a German Company of Berlin and Munich, Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: - This invention relates to utlrasonic imaging apparatus. One aspect of the invention relates to an ultrasonic imaging apparatus operating on the pulse-echo principle, for example for medical diagnosis, with an ultrasonic applicator for the linear ultrasonic scanning of an examination subject and an image display device, including a line sweep generator for representing the echo pulses by lines and also an image generator for the displacement of the lines as a function of the displacement of the ultrasonic beam in the subject.

In the case of this type of ultrasonic imaging apparatus it would be very suitable to use standard television monitors as image display devices for the echo sectional image. However, this creates difficulties as the echo signal-receiving times for covering a desired whole image area in the examination subject are relatively long in comparison with the short standard line sweep times of a television picture tube. It is possible to solve this problem by operating with so-called full image storage of the ultrasonic full image. With this type of full image storage technique therefore the whole image could be stored slowly in complate lines in chronological sequence to correspond to the relatively slow time of occurrence of echo signals and then be read out again in the essentially quicker readout operation in television standard on the television picture tube. However, the full image storage technique requires a large number of individual stores, so that the apparatus is bulky and, what is more, expensive.

According to this invention there is provided ultrasonic imaging apparatus, which operates according to a pulse-echo principle, the apparatus comprising: an ultrasonic applicator, for line-by-line scanning of a body, image display means, which includes line sweep generating means, for representing echo pulse signals by lines, and means for displacing such lines as a function of the displacement of an ultrasonic beam transmitted during scanning by the applicator, and image conversion means, for converting echo pulse signals to a form suitable for display by the image display means, the image conversion means including: two buffer stores, for storing echo pulse signals of scan lines scanned by the applicator, supply means for supplying echo pulse signals of successive scan lines to alternate ones of the two buffer stores, read-out means, for reading-out echo pulse signals from the two buffer stores alternately for supply to the image display means, and control means, for controlling transmitting/receiving cycles of the apparatus such that the period of each transmitting/receiving cycle is an integral multiple greater than unity of the line sweep period, and for controlling the supply means and the read-out means such that echo pulse signals of each transmitting/receiving cycle are supplied to one of the two buffer stores until the next transmitting/receiving cycle when they are read-out during the simultaneous supply of echo pulse signals to the other buffer store.

The control means could be arranged such that the period of each transmitting/ receiving cycle is three times the line sweep period and, accordingly, the echo pulse signals of each scan line are read-out three times in succession.

The control means could comprise counting means for controlling transmitting/ receiving cycles of the apparatus, the counting means being arranged to count line synchronising pulses of a picture signal supplied to the image display means.

In this case, clock pulse generating means could be provided for controlling production of the line synchronising pulses, the clock pulse generating means preferably generating pulses with a frequency of 15.625 KHz.

In the case of ultrasonic imaging apparatus provided with clock pulse generating means, there could be provided blanking pulse generating means, arranged to be controlled by the clock pulse generating means, for producing blanking pulses for the picture signal supplied to the image display means and for controlling the frequency of reading-out of echo pulse signals stored in the buffer stores. Such blanking pulse generating means could comprise two monostable flip-flops.

The invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 shows a circuit diagram of ultrasonic video apparatus according to one example of the invention, and Figure 2 shows signal waveforms produced during a video standard conversion process using the apparatus shown in Figure 1.

Referring to Figure 1, an ultrasonic am plicator 1 is constructed as an ultrasonic array comprising a plurality of ultrasonic transducers, We to Wn (piezoelectric crystal plates), which are fixed side by side in a row on a carrier member 2. This member 2 is made of a material which effectively damps ultrasonic waves. The transducers Wl to Wn may be selectively energised either individually or in groups, by means of high frequency pulses produced by a high frequency pulse generator 3, so that they radiate ultrasonic pulses into an examation subject 5, for example a human body, in the direction indicated by arrows 4. The control of the transducers W1 to Wn in to individual or group formation is effected by means of a control device which comprises a control shift register 6 and control switches Si to Sn. This control device connects the transducers which are to be energised with the high frequency pulse generator 3 in the transmitting cycle, or with an echo pulse receiver amplifier 7 in the receiving cycle. The shift register 6 of the control device ensures that, by means of controlling the switches Si to Sn, the transducers Wi to Wn respectively may be continuously switched in succession to trans mit or receive, either individually or in groups. A linear progression of an ultrasonic transmitting/receiving beam is thus produced over the row of transducers W1 to Wn with corresponding linear ultrasonic scanning of the examination subject 5. A conventional television monitor 8 is used for displaying the echo signals of each ultrasonic scanning line by a corresponding image line. This television monitor 8 comprises a television picture tube 9 with which there is associated, in the normal way, a line sweep generator 10 for supplying a horizontal deflection coil 11 and an image (field) sweep generator 12 for supplying a vertical deflection coil 13 of the television picture tube 9. The monitor 8 further comprises an intensity modulator 14, for intensity modulation of the image lines of the line-scanning pattern at the frequency of the echo pulses being produced, and a pulse isolating stage 15 for the variable information contents of a picture (BAS) signal fed to the monitor 8.

This picture (BAS) signal occurs at the output of a mixer stage 16 which has inputs supplied by echo signals, horizontal or vertical blanking pulses and also line or image synchronising pulses. The echo signals are supplied from the output of the echo pulse receiver amplifier 7 via two buffer stores 17 and 18 which are controlled in a counter clock pulse manner by means of two oscillating switches 19 and 20, and also via a further amplifier 21 for amplifying the echo signals. A blanking pulse generator 22, 23 and a synchronising pulse generator 24 are used for producing the horizontal (or vertical) blanking pulses and the line (or image) synchronizing pulses respectively. The blanking pulse generator 22, 23 includes two monostable flip-flops 22 and 23 which are pulsed in chronological sequence at the frequency of clock pulses TG produced by a basic clock pulse generator 25. Two pulse trains TA and TzI respectively (shown in Figure 2) thus result from the basic frequency produced by the basic clock pulse generator 25 which oscillates at the normal line sweep frequency of the television picture tube 9, of 15.625 KHz for example. The basic clock pulse generator 25 also supplies clock pulses TG to the synchronising pulse generator 24 which is similarly formed by a monostable flip-flop which produces transient synchronised pulses having a clock pulse waveform THUS. The picture (BAS) signal is thus produced, having the waveform shown in Figure 2, by superposition of the blanking pulses Tzr with the synchronising pulses TES (TVS) and the echo signals. After isolation in the pulse isolating stage 15 of the television monitor 8, a line sweep voltage Z, is triggered by the horizontal synchro nising pulses T11s. At the end of each image synthesis an image synchronising pulse is produced together with an image blanking pulse which causes the return of the electron beam of the television picture tube 9 to the output position and re-triggering of a further image sweep by the line-scanning waveform ZK. To determine the transmitting/receiving times of the ultrasonic transmitter/receiver cycles, a counter 26 is used to count the synchronising pulses TEs (Tvs) produced by the synchronising pulse generator 24. For every fourth synchronising pulse THB (Tvs), this counter 26 produces an output pulse TL which acts as a control clock pulse to produce further clock pulsing of the register positions in the shift register 6 and hence corresponding successive switching of the switches S, to S". Also, the high frequency pulse generator 3 is simultaneously energised on the appearance of a control clock pulse Tl, to emit a high frequency pulse to those transducers Wi to Wn connected by the switches S1 to S" respectively. Linear ultrasonic scanning of the examination subject 5 is thus produced at the frequency of the control clock pulse TL. Alternate switching of the switches 19 and 20 is also governed by the control clock pulses TL. In Figure 2 the switch-over times at the store inputs, and the switch-over times at the store outputs, are designated in each case by TE17 and TEI8 respectively and TAI7 and Taxi, respectively. The pulses shown with hatching designate in each case the duration of the reading-in of echo signals in to one store with the simultaneous reading-out of the information representing a previous echo line held in the other store. The actual reading-out of data held in the stores 17 and 18, the outputs of which are connected via the amplifier 21 to the mixer stage 16, takes place at the synchronising frequency of the output pulses TZI of the blanking pulse generator 22, 23 via the read-out control lines 27 and 28 respectively. Since three blanking pulses Tzi always occur in chronological succession during the period of control of one store 17 or 18 by the output switch 20, one echo line, stored in the relevant connected store 17 or 18, is read-out three times in all in chronological succession. An echo image is therefore produced on the screen of the elevision picture tube 9 having a high line density and relatively high frame speed, with each line being reproduced three times.

The embodiment described operates according to the simple full image principle.

However, a line jump technique may also be used such that, with even-numbered multiples of the horizontal synchronising pulses, ultrasonic scanning of the lexamina- tion subject and the corresponding picture line reproduction on the television picture tube takes place, for example, in two successive half-pictures (or fields) according to an interlaced scanning method. In this case the multiple reproduction of an echo line is half an even-numbered multiple of the number of the horizontal synchronising pulses.

WHAT WE CLAIM IS: 1. Ultrasonic imaging apparatus, which operates according to a pulse-echo principle, the apparatus comprising: - an ultrasonic applicator, for line-by-line scanning of a body, image display means, which includes line sweep generating means, for representing echo pulse signals by lines, and means for displacing such lines as a function of the displacement of an ultrasonic beam transmitted during scanning by the applicator, and image conversion means, for converting echo pulse signals to a form suitable for display by the image display means, the image conversion means including: two buffer stores, for storing echo pulse signals of scan lines scanned by the applicator, supply means for supplying echo pulse signals of successive scan lines to alternate ones of the two buffer stores, read-out means, for reading-out echo pulse signals from the two buffer stores alternately for supply to the image display means, and control means, for controlling transmitting/receiving cycles of the apparatus such that the period of each transmitting/receiving cycle is an integral multiple greater than unity of the line sweep period, and for controlling the supply means and the readout means such that echo pulse signals of each transmitting/receiving cycle are supplied to one of the two buffer stores until the next transmitting/receiving cycle when they are read-out during the simultaneous supply of echo pulse signals to the other buffer store.

2. Ultrasonic imaging apparatus according to claim 1, wherein the control means is arranged such that the period of each transmitting/receiving cycle is three times the line sweep period and, accordingly, the echo pulse signals of each scan line are read-out three times in succession.

3. Ultrasonic imaging apparatus according to claim 1 or 2, wherein the control means comprises counting means for controlling transmitting/receiving cycles of the apparatus, the counting means being arranged to count line synchronising pulses of a picture signal supplied to the image display means.

4. Ultrasonic imaging apparatus ac

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. nising pulses T11s. At the end of each image synthesis an image synchronising pulse is produced together with an image blanking pulse which causes the return of the electron beam of the television picture tube 9 to the output position and re-triggering of a further image sweep by the line-scanning waveform ZK. To determine the transmitting/receiving times of the ultrasonic transmitter/receiver cycles, a counter 26 is used to count the synchronising pulses TEs (Tvs) produced by the synchronising pulse generator 24. For every fourth synchronising pulse THB (Tvs), this counter 26 produces an output pulse TL which acts as a control clock pulse to produce further clock pulsing of the register positions in the shift register 6 and hence corresponding successive switching of the switches S, to S". Also, the high frequency pulse generator 3 is simultaneously energised on the appearance of a control clock pulse Tl, to emit a high frequency pulse to those transducers Wi to Wn connected by the switches S1 to S" respectively. Linear ultrasonic scanning of the examination subject 5 is thus produced at the frequency of the control clock pulse TL. Alternate switching of the switches 19 and 20 is also governed by the control clock pulses TL. In Figure 2 the switch-over times at the store inputs, and the switch-over times at the store outputs, are designated in each case by TE17 and TEI8 respectively and TAI7 and Taxi, respectively. The pulses shown with hatching designate in each case the duration of the reading-in of echo signals in to one store with the simultaneous reading-out of the information representing a previous echo line held in the other store. The actual reading-out of data held in the stores 17 and 18, the outputs of which are connected via the amplifier 21 to the mixer stage 16, takes place at the synchronising frequency of the output pulses TZI of the blanking pulse generator 22, 23 via the read-out control lines 27 and 28 respectively. Since three blanking pulses Tzi always occur in chronological succession during the period of control of one store 17 or 18 by the output switch 20, one echo line, stored in the relevant connected store 17 or 18, is read-out three times in all in chronological succession. An echo image is therefore produced on the screen of the elevision picture tube 9 having a high line density and relatively high frame speed, with each line being reproduced three times. The embodiment described operates according to the simple full image principle. However, a line jump technique may also be used such that, with even-numbered multiples of the horizontal synchronising pulses, ultrasonic scanning of the lexamina- tion subject and the corresponding picture line reproduction on the television picture tube takes place, for example, in two successive half-pictures (or fields) according to an interlaced scanning method. In this case the multiple reproduction of an echo line is half an even-numbered multiple of the number of the horizontal synchronising pulses. WHAT WE CLAIM IS:

1. Ultrasonic imaging apparatus, which operates according to a pulse-echo principle, the apparatus comprising: - an ultrasonic applicator, for line-by-line scanning of a body, image display means, which includes line sweep generating means, for representing echo pulse signals by lines, and means for displacing such lines as a function of the displacement of an ultrasonic beam transmitted during scanning by the applicator, and image conversion means, for converting echo pulse signals to a form suitable for display by the image display means, the image conversion means including: two buffer stores, for storing echo pulse signals of scan lines scanned by the applicator, supply means for supplying echo pulse signals of successive scan lines to alternate ones of the two buffer stores, read-out means, for reading-out echo pulse signals from the two buffer stores alternately for supply to the image display means, and control means, for controlling transmitting/receiving cycles of the apparatus such that the period of each transmitting/receiving cycle is an integral multiple greater than unity of the line sweep period, and for controlling the supply means and the readout means such that echo pulse signals of each transmitting/receiving cycle are supplied to one of the two buffer stores until the next transmitting/receiving cycle when they are read-out during the simultaneous supply of echo pulse signals to the other buffer store.

4. Ultrasonic imaging apparatus ac

cording to claim 3, wherein there is provided clock pulse generating means for controlling production of the line synchronising pulses.

5. Ultrasonic imaging apparatus according to claim 4, wherein the clock pulse generating means generates pulses with a frequency of 15.625 KHz.

6. Ultrasonic imaging apparatus according to claim 4 or 5, wherein there is provided blanking pulse generating means, arranged to be controlled by the clock pulse generating means, for producing blanking pulses for the picture signal supplied to the image display means and for controlling the frequency of reading-out of echo pulse signals stored in the buffer stores.

7. Ultrasonic imaging apparatus according to claim 6, wherein the blanking pulse generating means comprises two monostable flip-flops.

8. Ultrasonic imaging apparatus substantially as herein described with reference to the accompanying drawings.