JPS63296734A - Digital scanning converter - Google Patents

Abstract

PURPOSE:To flexibly deal with even pictures different in display and scanning systems and to realize DSC reduced in the increase of capacity accompanied by an increase in a degree of freedom even if said degree of freedom increases, by applying coordinates transformation to the sound ray data corresponding to each of the coordinates of the region to be displayed of an image data memory means of orthogonal coordinates by a coordinates transformation means and interpolating said data by an interpolation means before writing the same in an image data memory means. CONSTITUTION:Inputted analogue sound ray data is converted to a digital signal by an A/D converter 11 to be written in a sound ray memory 12. A mapping circuit 13 generates a display memory writing address along the arbitrary axis among X- and Y-axes with respect to the mapping objective region in a display memory 15 and calculates the address of the sound ray memory 12 corresponding to each pixel of the display memory 15 corresponding to said writing address and reads data from the sound ray memory 12 to write the same in the display memory 15. When the data just corresponding to the pixel of the above-mentioned display memory 15 in the region written in the sound ray memory 12 is not present in the sound ray memory, interpolation data is calculated from the data at several vicinal points by an interpolator 14.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a digital scan converter that converts an ultrasonic reception signal of an ultrasonic diagnostic apparatus into a television format signal.

(Prior art) An ultrasonic diagnostic device irradiates ultrasound signals into the subject's body and displays on a TV-type monitor the differences in reflected waves caused by normal tissues and lesions within the subject's body, or due to the distance between group 11, etc. I am observing. As a method of displaying this, a digital scan converter (hereinafter referred to as DSC) is used to convert the scanning of the ultrasonic signal by the probe into standard TV scanning, and
The method of displaying on a V monitor is mainly used. D
There are two methods (1) and (2) below for writing to the frame memory in the SC. One method is to write to the frame memory as it is in rectangular coordinates, and the other method is to write to the frame memory as it is in rectangular coordinates. This method takes and writes the sound ray number on the horizontal axis.

(1) The DSC performs ΔD conversion on the echo signal, writes it into a frame memory of orthogonal coordinates, reads it using standard TV scanning, converts it from analog to analog, and displays it on a TV monitor. If the ultrasonic diagnostic apparatus is performing sector scanning, the xY coordinates are digitized when written into the digital memory, so if displayed as is, an image with moire fringes will be displayed. In order to avoid this, it is necessary to perform appropriate interpolation between ultrasound scanning lines. Therefore, during the transmission/reception period of a sound ray, the vixels in the partial sector area between that sound ray and the adjacent sound ray are filled in with sufficient interpolation. In this method, it is necessary to have information on the shape of the partial sector handled for each transmission/reception period, and to know which pixel to write data into.The pixel into which the corresponding sound ray data is written is calculated each time. have to find the location. Since this calculation is complex, it is necessary to prepare conversion data in advance in a table-format memory or the like. In this case, changing the magnification.

Changing the display by rotating the display, changing the sound ray density, introducing convex scanning, etc. requires a different table each time, and the greater the degree of freedom, the larger the table capacity must be. If the enlargement ratio could be changed arbitrarily, an enormous table capacity would be required.

(2) In the case of a frame memory that takes the depth on the vertical axis and the sound ray number on the horizontal axis (in sector scan or convex scan, the vertical axis takes r and the horizontal axis takes θ), the irradiation of the sound ray to be written Since these are not parallel, the shape must be changed and interpolated when read out in accordance with the TV format (Cartesian 11[). Originally not parallel 4: Since the Yang lines are written in parallel, when reading, the locus of the address must be read as a curved line, and when reading this, the TV display is performed while calculating the address along the curved line. A read address must be generated at the dot clock cycle.

(Problem to be Solved by the Invention) In the case of (1) above, in addition to the required capacity of the table increasing, if the image enlargement ratio increases, the data must be written within the transmission and reception period of the same sound ray. The number of pixels increases. Since there is a limit to the writing time to the frame memory, it is necessary to lengthen the sound ray period and lower the frame rate to increase the writing time.If you do not do this,
Interpolation cannot be performed sufficiently, and it becomes necessary to insert interpolated data when reading in the rask direction.

If this is done, for example, if the angle of the sector scan is tilted, satisfactory interpolation will not be possible because the read direction is a rectangular coordinate axis. This state is shown in FIG. In the figure, a tilted sector scan image 2 is displayed on a display screen 1. For example, to interpolate points A and B between sound rays 3 and 4, either take the midpoint of the string AS on the same circumference, like the 0 point in the diagram, or take the midpoint of line segment AB. Although it is necessary (here, 0A=OB), when interpolating at the time of reading, the straight line PQ parallel to the horizontal axis and the sound ray 3. The midpoint R of the line segment PQ formed by the intersections P and Q of the sounds 14 must be taken, which results in an error.

When the vertical axis is the sound ray depth and the horizontal axis is the sound ray number, as in case (2) above, the frame memory is read out along the curved line at the cycle of the TV's dot clock. Arithmetic operations must be performed, and the address generation system is required to be extremely fast, and if this were to be performed using arithmetic operations, the equipment would be expensive. Rather than using calculations,
It would be possible to use a table format, but then, as in (1), the table capacity would increase as the degree of freedom increases. Furthermore, in this system, if a composite display is to be performed in which a plurality of screens are displayed on the same display screen, a plurality of similar mechanisms are required, making the system even more complex and large-scale. the above(
In both methods 1) and (2), the operating speed of the DSC (address conversion speed) depends on whether it is in Japanese/American format or Western format.
Or, it is greatly influenced by the TV format, such as whether it is standard speed or double speed. The present invention has been made in view of the above points, and its purpose is to provide a different display format.

The object of the present invention is to realize a DSC that can respond flexibly to screens of different scan formats, and that increases the degree of freedom with less increase in size.

(Means for Solving the Problems) The present invention solves the above-mentioned problems by using a digital scan converter that converts an ultrasound reception signal of an ultrasound diagnostic apparatus into a television format signal. a sound data storage means for writing the sound ray data according to the coordinates, where the abscissa is the depth of the 9 reflection points on the sound ray, and a right angle for recording the sound ray data converted into a television format signal. coordinate image data storage means, and coordinate conversion means for reading out the sound ray data to be written to each coordinate of the image data storage means existing in the display target fr4 band from the sound ray data storage means and writing it into the image data storage means. and an interpolation means for interpolating the sound ray data based on the read address of the coordinate conversion means.

(Function) The received signal obtained by scanning in any format is written into the sound ray data storage means based on sound ray and depth coordinates, and the sound corresponding to each coordinate of the display target area of the image data storage means using rectangular coordinates is recorded. The line data is coordinate-converted by the coordinate conversion means, interpolated by the interpolation means, and then written into the image data storage means.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of one embodiment of the present invention.

In the figure, 11 is a ΔD converter that converts analog sound ray data from reflected waves from within the subject into digital sound ray data, and 12 is an AD converter that indicates the sound ray number in the horizontal direction and the depth in the vertical direction. This is a sound ray memory into which the sound ray data of output No. 11 is written. The sound ray memory write address is given from an address generator (not shown) in conjunction with the transmission and reception of ultrasonic waves. The data stored in the sound ray memory 12 is read out using the sound ray memory read address from the mapping circuit 13, and the data is interpolated between the sounds I11 by the interpolator 14 and written into the display memory 15. The display memory write address is output from the mapping circuit 13.

A read address matching the TV format is given to the display memory 15 from a predetermined address generator (not shown), and the output data is converted into an analog signal by a DA converter 16 and sent to a CRT (not shown). will be displayed.

Next, the operation of the embodiment configured as described above will be explained.

The input analog sound ray data is converted into a digital signal by the AD converter 11 and written into the sound ray memory 12 . The data stored in the sound ray memory 12 is structured such that the vertical axis represents the depth and the horizontal axis represents the sound ray number. The mapping circuit 13 generates a display memory write address along an arbitrary axis of the X axis or the Y axis for the mapping target area in the display memory 15, and generates a sound corresponding to each pixel of the display memory 15 corresponding to this write address. line memory 1
2 is calculated and obtained, the data is read from the sound ray memory 12 and stored in the display memory 15. If there is no data in the sound ray memory 12 that exactly corresponds to a pixel of the display memory 15 in the area inserted into the sound ray memory 12, interpolated data is calculated in the interpolator 14 from data at several points in the vicinity. . The sound ray memory read address input to the interpolator 14 is used for weighting in interpolation data calculation. The sound ray data read from the sound ray memory 12 is interpolated as necessary as described above, and is stored in the display memory 15 according to the display memory write address.
be refined. The data written in the display memory 15 is read out using a read address matching the TV format, converted into an analog signal by the DA converter 16, and displayed on a CRT.

Next, the operation of the mapping circuit 13 will be explained in detail in the case of sector scan with reference to FIG. In the figure, reference numeral 5 denotes a mapping target area set in the display memory 15 by the mapping circuit 13, and only this area is scanned during writing and reading. 6 is a sector scan area in the mapping area, and all data is written in this area. In reading data from the sound ray memory 12, the mapping circuit 13 first generates a display memory write address along any axis, either the X axis or the Y axis, of the mapping target area 5 in the display memory 15, The following equation is calculated for each point (X, Y) of the address.

r= + , θ-tan −' (x/Y)
(1) If these r and θ are within the values that the mapping circuit 13 recognizes as being within the sector scan area 6, this pixel exists within the sector scan area 6, and the sound ray memory 12
Since all the sound ray data of one frame in the sector scan area 6 is read into the field, all the data corresponding to the above-mentioned pixels are included in the range of the sound ray data written in the sound ray memory 12. There is. Therefore, the data at the coordinates (r, θ) determined from equation (1) is read out using the sound ray memory read address, passes through the interpolator 14, and is written into the display memory 15. If the coordinates of (', θ) determined by equation (1) do not exactly correspond to the address of the sound ray memory 12, the data of several nearby points are distributed proportionally according to the fractional value of the sound ray memory read address. interpolated data is calculated and written into the display memory 15.

FIG. 4 shows a case where sector scanning is performed at an angle. In the figure, parts equivalent to those in FIG. 3 are given the same reference numerals. Assuming that the x, ■ coordinate axes are tilted by an angle φ with respect to the XY coordinate axes, the following equation is calculated.

x=Xcosφ+y sinφ y−−Xsinφ+y cosφ (2) After calculating equation (2), equation (1) is calculated to obtain polar coordinates.

The magnification rate is used to enlarge or reduce the display.

You only need to calculate by multiplying the reduction rate, and there is no need to prepare many tables. Therefore, the parameters for the mapping circuit 13 to calculate for changes in the position of the sector scan area are the movement m1 of the origin between the X, Y coordinates of the display memory address and the xy coordinate of the physical system of the sector scan.
All that is required is the rotation angle and magnification, coefficients for determining the depth and sound ray number from polar coordinates or xy coordinates, and bias amounts such as the starting point of the scan.

In addition, for conversions due to enlargement, reduction, and rotation, the amount of change ΔXy in the X-axis direction and the X-axis direction corresponds to the movement of 1 pixel in the X-axis direction.
, Δyx, the amount of change Δxy in the X-axis and V-axis directions corresponding to the movement of 1 pixel in the Y-axis direction.

This can be done by determining ΔVv. Therefore, the xy coordinate representation of the display memory can be obtained by cumulative addition of the minute changes described above.

As described above, since the sound ray memory has one frame's worth of all sound ray data, the data can be read out at any time using an address calculated simply from the display system address. As a result, it is sufficient to perform the coordinate transformation according to the formula, and the only necessary parameters are the coefficients of the numerical edges necessary for the coordinate transformation and the bias value indicating the start value.

Furthermore, by providing a display memory 15 and temporarily storing the scan-converted data in the display memory 15, the above-mentioned scan conversion can be performed independently and with a different clock from the display on the CRT, which does not require particularly high speed. Scan conversion can be performed using practical circuit elements without any problems. Furthermore, it has become possible to perform composite image display in which screens of different display formats and scan formats are displayed simultaneously, which was not possible with conventional methods. - (Effects of the invention) As explained in detail above, by simply having two sets of memories, various image displays such as coordinate conversion, scan format changes, enlargement ratio changes, composite display, etc. can be freely performed. It is possible to realize a DSC that does not require an increase in capacity, which has a great practical effect.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of one embodiment of this embodiment, Fig. 2 is a diagram showing an example of interpolation using the conventional method, Fig. 3 is an explanatory diagram of image conversion by a mapping circuit, and Fig. 4 is a diagram showing tilted sector scanning. FIG. 3 is an explanatory diagram of Okeko image conversion. 1... Display screen 2... Sector scan image 3.4... Sound ray 5... Sector scan area 11... AD converter 12... Sound ray memory 13.
... Mapping circuit 14 ... Interpolator 15 ... Display memory 16 ...
...DA converter patent applicant Yokogawa Medical System Co., Ltd. Procedural amendment writer volunteer)

Claims (1)

[Claims] In a digital scan converter that converts the ultrasound reception signal of an ultrasound diagnostic device into a television format signal, the sound ray data is converted into a digital scan converter, with the sound ray of the ultrasound beam as the abscissa and the depth of the reflection point above the sound ray as the ordinate. sound ray data storage means for writing according to the coordinates; image data storage means for rectangular coordinates for storing the sound ray data converted into television format signals; and each coordinate of the image data storage means existing in the display target area. coordinate conversion means for reading out the sound ray data to be written into the sound ray data storage means and writing it into the image data storage means; and interpolation means for interpolating the sound ray data based on a read address of the coordinate conversion means. A digital scan converter comprising: