JPH065274B2 - Video display - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video display device for displaying a signal obtained from a device for displaying polar coordinates such as PPI scan of radar by raster scan.

[Conventional technology]

In general, a radar image display is performed by a PPI scan for displaying an image on a display surface 2 formed by rotating a sweep line 1 extending from the center in the circumferential direction in synchronization with the rotation of an antenna as shown in FIG. It is being appreciated. However, this method requires a cathode ray tube with afterglow and has the drawback that the screen must be viewed through the hood because of its low brightness, so in recent years, signals obtained by PPI scanning are raster-scanned. It has been proposed to convert and display.

In case of PPI scan, points 11 to 1n on sweep line 1
Is the angle θ that changes clockwise from the reference point 3 in FIG.
Then, the coordinates of the points 11 to 1n can be represented by the distance from the center. On the other hand, in the case of raster scan,
When the center of the circle of the points 11a to 1na on the scanning line 4 is defined as the display start point 5, the coordinates can be represented by the vertical position and the horizontal position from the display start point 5.

From this, in order to convert the position information of the points 11 to 1n in the PPI scan into the position information of the points 11a to 1na in the raster scan, a minute position change in the vertical direction in the raster scan based on the value of the angle θ in the PPI scan. The amount Δcos θ and the minute positional change amount Δsin θ in the horizontal direction are obtained, and by accumulating these values, points 11a to 1n corresponding to points 11 to 1n on the virtual line 1a corresponding to the sweep line 1
You can determine the coordinate of a.

In this way, the coordinates of the points 11a to 1na in the raster scan are determined, and the values are stored in the memory together with the luminance data at that point. The brightness data at this time is from point 1a to
Intensity data of 1n is used. And sweep line 1
When the data is stored in the memory in accordance with the movement of, and the data is read in the scanning order and displayed, the signal of the PPI scan is converted into the raster scan and displayed.

[Problems to be solved by the invention]

However, since such a conventional device can display only the position on the scanning line, when a circle centered on the display starting point 5 is displayed in order to display the range mark which is the distance marker, the circle is displayed. It has a drawback that it is displayed as a discontinuous line and is difficult to see.

[Means for solving problems]

In order to solve such a drawback, the present invention has a coordinate conversion unit that sequentially converts points on a PPI sweep line into points on a raster scanning line at a predetermined processing timing, and a coordinate conversion unit sequentially converts the points on a raster scanning line. The three consecutive points are the next adjacent preceding point, the adjacent preceding point, and the current display point in order from the latest one. Of these, the vertical and horizontal directions are defined by the intervals of the raster scanning lines and are points on the PPI sweep line corresponding to the current display point. A group selection unit that sets a point located at any one of the corners of the square area including the conversion point as a group of emission points for the conversion point, and each emission point set by the group selection unit from the conversion point. A luminance setting unit that sets the luminance inversely proportional to the distance, a first delay circuit that delays the luminance output of the light emitting point corresponding to the adjacent preceding point of the luminance setting unit by one processing timing, and the luminance setting unit. A second delay circuit for delaying the luminance output of the light emitting point corresponding to the next adjacent preceding point of the section by two processing timings, the luminance output of the light emitting point corresponding to the current display point of the luminance setting section, and the first delay circuit An output and a data conversion unit for selecting the maximum output of the second delay circuits.

[Action]

The position of the point to be displayed by the raster scan method is determined based on the position data of the polar coordinate method, and the brightness of each display point is determined based on this. Regarding the brightness of each display point, the brightness of the next adjacent preceding point, the adjacent preceding point, and the current display point is calculated for a certain display point, and the maximum one is selected.

〔Example〕

FIG. 1 is a block diagram showing an embodiment of the present invention,
10 is a coordinate detection unit, 20 is a modulation factor setting unit, 30 is a data conversion unit, 40 is a smoothing control unit, 50 is a group selection unit, 51 is a clock control unit, 52 is a brightness setting unit, 53 is a selector, and 54 to 56 are The shift register, 60 is a scan converter.

If the current display point on the raster scan line that is currently displayed on the raster is the m-th point from the display start point 5, the coordinate detection unit 10 precedes this current display point m in the preceding display direction (display start point 5 The coordinates of the adjacent preceding point (m + 1) adjacent to the raster scanning line in the direction away from () and the coordinates of the next adjacent preceding point (m + 2) adjacent to the adjacent preceding scanning point (m + 1) on the raster scanning line in the preceding display direction. It is designed to calculate. As shown in FIG. 2, the coordinate detecting section 10 is composed of registers 11, 13 and adders 12, 14. FIG. 2 shows a portion for accumulating Δsin θ, and although not shown, Δco has the same configuration as that in FIG.
There is a part that accumulates sθ.

The modulation degree setting unit 20 includes ROMs 21 to 21 as shown in FIG.
24 on the raster scanning line based on the signals supplied from the coordinate detecting unit 10 and the group selecting unit 50, that is, the current display point m, the adjacent preceding point (m + 1),
A signal for brightness modulation of the next adjacent preceding point (m + 2) is transmitted.

Three points on this raster scan line, that is, the current display point m,
The positional relationship between the adjacent preceding point (m + 1) and the next adjacent preceding point (m + 2) is determined to be one of the states shown in FIGS. 4 (a) to (e). 4 (a) to (e)
Is an example including an example in which two of the three display points are at the same place and two points are displayed in appearance.

In FIG. 4, each display point is on the raster scanning line,
The side distance is a value corresponding to the interval between adjacent raster scanning lines, and the range surrounded by the four sides is defined as a pixel. Since this pixel represents a range surrounded by four adjacent display points as shown in FIG. 12, it has the same size as the light emitting point (so-called pixel) on the scanning line of the display.

At this time, the relationship between the distance between adjacent coordinate-converted dots on the PPI scanning line (sweep) and the distance between the adjacent light emitting points on the raster scanning line is as follows.

The coordinate conversion of the sweep is as follows when the angle is θ as shown in FIG.

xn = sin θ × m yn = con θ × m Here, m is the number of cumulative additions, and the basic value of cumulative addition is as follows.

x = 1 × sin θ y = 1 × cos θ Therefore, the interval between dots (calculated dots, that is, ideal coordinates) that is printed when m increases by 1 is always 1. FIG. 13 shows this state, and the black circles on the sweep are ideal coordinates.

By the way, since the maximum straight line length within one pixel of the area shown by the thick line portion in FIG. 14 is 2 ^1/2 , it is larger than the required length “1” of two dots and the required length “2” of three dots. Shorter than. This means that as shown in FIG. 14, the ideal coordinates indicated by black circles cannot be displayed during raster scanning, so the points indicated by circles are displayed, and as a result, two dots may be printed within one pixel. . Then, the display is performed on the adjacent display point for the first time at the third dot.

Of course, as shown in FIG. 15, the ideal coordinates and the points actually displayed may all be different.

Further, as shown in FIG. 16, the maximum straight line length in the four pixels in the area shown by the thick line portion is 2 × 2 ^1/2 , which is shorter than the required length “3” of four dots. This means that the fourth dot cannot be an adjacent display point to be modulated, as shown in FIG.

As described above, the display point can be set only on the scanning line. However, if two points are emitting light and the brightness is the same, and if the distance between the two points is close, it seems that the light emitting point is in the center between the two points and the brightness of the two points is If they differ, the light emitting point seems to be in the higher brightness.

In the case of FIG. 4 (c), if the display point “a” and the display point “d” have the same brightness, the apparent display point is in the center of the pixel, but the display point “a” has a higher brightness. As it does, the apparent display point becomes closer to the display point "a".

The modulation degree setting unit 20 is for generating a signal for determining the brightness of the display point in this way and setting the apparent display point at an arbitrary position in the pixel.

The data conversion unit 30 is composed of a ROM having a comparator function, and selects the maximum one of the three types of brightness data supplied to the input side.

As shown in FIG. 5, the smoothing control unit 40 includes a latch 41, a comparator 42, a shift register 43,
44, delay circuit 45, OR circuits 46, 47, 48, 4
9. When a graphic with a large area is displayed, the AND circuit 49a is configured to output a signal indicating whether or not the current display point is the outline of the graphic, and in response to the signal. The selector 53 selects and outputs the brightness-modulated data supplied from the data converter 30 and the data before brightness modulation supplied from the scan converter 60.

The group selection unit 50 is a ROM, and is shown in FIG. 4 (a).
Signals indicating which display state (e) is displayed are generated, and each signal is defined as shown in Table 1.

At the same time, as shown in Table 2, a signal is generated which indicates which dot is shown in FIGS. 4 (a) to 4 (e).

The definitions of the main line dots and the supplementary line dots will be described later.

The brightness setting unit 52 is a ROM, and the brightness data before brightness modulation transferred from the scan converter 60 is brightness-modulated by the data representing the modulation degree supplied from the modulation degree setting unit 20 and supplied from the scan converter 60. The brightness-modulated data is output as shown in FIG. 6 corresponding to the data representing the modulation degree. The brightness change in FIG. 6 is set so that the curve is smoothly displayed while considering the exponential change according to the visual characteristics.

The operation of the device configured as described above is as follows. First, the scan converter 60 sends accumulated basic value data for converting polar coordinate data into rectangular coordinate data. This data is the horizontal minute distance data Δsin θ and the vertical minute distance data Δcos θ corresponding to the sweep angle θ in FIG. The coordinate detection unit 10 has two circuits shown in FIG. 2, one of which is supplied with Δsinθ data and the other of which is supplied with Δcosθ data. Different types and the timing pulse CK1 supplied to the register 11
Since both have the same circuit and the same operation except that the timing is different, only the operation of the horizontal coordinate detecting portion shown in FIG. 2 will be described.

When the horizontal small distance data Δsin θ is supplied from the scan converter 60 and the timing pulse CK1 is supplied from the clock control unit 51 to the coordinate detection unit 10, the register 11 shown in FIG. The captured data is held until the clock pulse CK1 is supplied.

The clock pulse CK1 is generated every one sweep, and therefore, the captured data is retained during the sweep from the center point to the outer peripheral end shown in FIG. 9, and the next sweep is performed. The data currently supplied to the register 11 at the time of start is newly taken into the register.

It should be noted that the vertical direction minute distance data Δcos θ is the timing pulse C at a timing different from the timing pulse CK1.
It is taken into the corresponding register by K3.

When the horizontal direction minute distance data Δsin θ is taken into the register 11, the clock pulse CK2 which is the scan conversion clock of the scan converter is successively supplied, so that this data is supplied by the adders 12 and 14 and the register 13 to the clock pulse CK2. Is accumulated every time is supplied.

At this time, the output signal 100 of the register 13 indicates the ideal coordinates in the pixel of the dot at that time, and the output signal 104 of the adder 12 obtained by adding Δsin θ to the value is the dot displayed next, that is, the output. Assuming that the dot of the signal 100 is displayed m-th (hereinafter, this dot is referred to as dot m), the output signal 104 is (m + 1).
The position of the dot displayed next (hereinafter, this dot is referred to as dot (m + 1)) is shown.

The carry signal 102 of the adder 12 represents whether or not the dot (m + 1) has moved to another pixel, and the carry signal 101 of the adder 14 is the (m + 2) th displayed dot [hereinafter, this dot is Dot (m + 2)] indicates whether or not the dot (m + 1) has moved to another pixel.

There are 16 combinations of carry signals, which are shown in FIG. However, as described above in the operation during coordinate conversion of the PPI sweep, the state without carry of three consecutive dots is that the required length “2” for three dots on the PPI sweep is the maximum straight line in the pixel. Since the length is larger than 2 ^1/2 , there is no actual operation in the pattern. Therefore, there are 15 combinations in this case.

Then, the coordinate detection unit 10 outputs a signal indicating the positional relationship between the dot (m + 1) and the dot (m + 2) with respect to the dot m and the ideal coordinates, that is, the position of the dot to be displayed, during the transfer of the dot m.

Of the signals output from the coordinate detection unit 10, the output signal 1
00 is supplied to the modulation degree setting unit 20, and the carry signal 10
1, 102 are supplied to the group selection unit 50. Since the coordinate detection unit 10 has two systems of circuits as described above, the modulation degree setting unit 20 is supplied with two types of signals and the group selection unit 50 is supplied with four types of signals.

Based on the supplied four types of carry signals, the group selection unit 50 indicates which of the dots m, (m + 1), (m + 2) the display position is (a) to (e) of FIG. This is output by the signal shown in Table 1, and what the constituent dots are at this time is output by the signal shown in Table 2.

Table 2 shows the main line dot m and the supplementary line dots (m + 1), (m
+2), the main line dot m is the above-mentioned m-th dot, and the brightness data is supplied from the scan converter 60 to this dot. The dot m is expressed as a main line dot m.

The complementary line dots (m + 1) and (m + 2) are the (m + 1) th dot and the (m + 2) th dot described above, and this dot is actually observed by the combined luminance of the main line dot and this dot. This is for deciding where to set the position to be set in the pixel.
As described above, the dots (m + 1) and (m + 2) are auxiliary dots, and therefore, when the constituent dots are expressed, these dots are expressed as complementary line dots.

However, the complementary line dots (m + 1) and (m + 2) may overlap with each other, and the complementary line dot (m + 1) may overlap with the main line dot m. Note that classification based on the data supplied from the scan converter 60 as shown in Tables 1 and 2 is defined as case classification.

The modulation degree setting unit 20 generates dots m, (m +) according to the ideal coordinate data of the dot m supplied from the coordinate detection unit 10 and the divided data supplied from the group selection unit 50.
1), the modulation degree is set, which is what kind of difference is made in the brightness of (m + 2).

As shown in FIG. 11, the display pattern of FIG. 4 divides the inside of a pixel to set the modulation degree, and the modulation degree can be selected from 16 types from 0 to 15. Since the gradation of the scan converter is 16 gradations, this is adapted to the characteristic. The operation of this part is as follows.

One of the five display patterns shown in FIG. 11 is selected from the group selection unit 50, and the display points a, b,
It is designated which of the dots m, (m + 1), and (m + 2) the dots c and d correspond to. At the same time, the coordinate detection unit 10 outputs a signal representing the position of the ideal coordinate within the pixel indicated by the black circle in FIG. The modulation degree setting unit 20 sets the modulation degree of the display point by an inversely proportional method using the ideal coordinates and the distances r _a and r _b to the actual display point based on the above information.

The setting at this time is such that the sum of the modulation degrees of the respective display points is 15, that is, the same as the brightness of the display point at the maximum brightness. As a result, the ideal coordinates, that is, the brightness of the apparent display point is always constant and displayed.

The modulation factor is stored in a P-ROM and divided into four groups as shown in FIG.
, Dot (m + 1), and dot (m + 2) output terminals are provided, and these are connected to each other by a bus. The coordinate data of the ideal coordinates is input to each group as a P-ROM address, and the display state and the constituent dot selection signal input by the group selection signal are input to the P-ROM output enable and address.

The group of ROMs 21 to 23 for two-point modulation is input with a display state selection signal, and ▲ ▼ as an output enable signal, to select a constituent dot. And (m + 2), and if "1", m and m + 1.

On the other hand, the three-point modulation as shown in FIGS. 11 (d) and 11 (e) is organized in one group in the ROM 24.

In this case, the constituent dot selection signal Table signal and display status selection signal at address The display state is shown in FIG. 11 (d), and if it is "1", the display state is shown in (e).

By the above operation, one state is selected, and the modulation degree of each dot m, (m + 1), (m + 2) is determined.

Since the modulation degree data sent from the modulation degree setting unit 20 is supplied to the brightness setting unit 52, the brightness setting unit 52 calculates the dots m, (m + 1), (m + 2) based on the brightness data supplied from the scan converter 60. ) Are set according to the characteristics shown in FIG. Of these data, the data of dot m is directly supplied to the data conversion unit 30, and the data of dot (m +) is the shift register 5.
The data of the dot (m + 2) is supplied to the data conversion unit 30 via the shift registers 54 and 55 via 6 Then, the data conversion unit 30 selects the data of the maximum brightness among the data of the dots m, (m + 1) a, and (m + 2) b supplied at the same time, and sends it to the selector 53.

Of the data selected at this time, dot (m + 1) a
Since the data of (1) passes through the shift register 56, the data of the processing is delayed from the data of the dot m by one processing. That is, when the dot (m-1) that is one process before the dot m is displayed, the data is determined by assuming the dot one dot ahead, that is, the dot m. From this, the brightness setting unit 5 is connected to the terminal c of the data conversion unit 30.
Both the data directly supplied from No. 2 and the data supplied via the shift register 56 are data representing the brightness of the dot m. Similarly, the shift registers 54, 5
Since the data supplied to the data conversion unit 30 via 5 is the data determined by assuming the dot two processing destinations from that point when displaying the dot (m-2), the dot m Data representing the luminance of the.

That is, when displaying the dot m in the modulation degree setting unit 20, the dot (m + 1) one dot ahead and the dot (m + 1) two dots ahead.
Three types of data of +2) are sent, but these dots (m + 1) are for one processing, and dots (m + 2)
Is delayed by the processing time of two processes. Therefore, the data conversion unit 30 is set at the timing of displaying the dot m.
Only the data of dot m is transmitted from the data.

As a result, the selector 53 is provided with two types of luminance data, the data that has passed through the data conversion unit 30 and the data that is sent from the scan converter 60. Then, one of these data is selected and transmitted by the signal supplied from the smoothing control unit 40.
It is displayed on a display unit (not shown). At this time, when the data from the data conversion unit 30 is selected, the display smoothing is performed.

In this way, by displaying the output from the data conversion unit 30, the contour portion can be displayed as a smooth line. However, performing smoothing is nothing but changing the brightness of each dot, so if such smoothing processing is performed on all data,
The unevenness occurs in a portion having an area, which makes it difficult to see. Therefore, such inconvenience can be avoided by performing the smoothing only on the portion where the luminance changes and not performing the smoothing on the portion where the luminance does not change. The smoothing control unit 40 shown in FIG. 5 performs such control.

Now, as shown in FIG. 7 (a), the screen displayed is composed of parts indicated by symbols a, b, and c, the brightness of each part is different, and the sweep is performed in the direction indicated by the arrow. An example of such a case will be described. When the data of the dot B is supplied to the terminal A of the comparator 42,
The terminal B of the comparator 42 is supplied with the data delayed by one clock by the latch 41, that is, the data of the dot A.

If the comparator 42 generates an output of "1" level when the data content of the terminal A and the data content of the terminal B are different, in this case, the brightness of the dot A and the dot B are different, so that the comparator 42 An output signal of "1" level is generated. This data is taken into the shift register 43 and sent from the terminals Q _A and Q _B , so that the OR circuit 4
It is supplied to the terminal S of the selector 53 via 8.

The selector 53 outputs the signal of the terminal B of the selector 53 when the signal of the “1” level is supplied to the terminal S, and outputs the signal of “0”.
If the signal of the terminal A of the selector 53 is output when the level signal is supplied, the data of the dot B is supplied from the data conversion unit 30 to the terminal B of the selector 53, and smoothing is performed. The output data is output. In this way, the initial timing of smoothing is determined.

The smoothing period is determined as follows, and the smoothing is performed by controlling the brightness of 2 dots or 3 dots as shown in FIG. Therefore, when performing smoothing, it is necessary to continuously perform smoothing for a maximum of 3 dots. Since the initial stage of smoothing is determined as described above, the smoothing period can be fixed by determining the final stage of smoothing. The period determined by the above operation is 2 dots. However, as described above, it may be necessary to perform smoothing for 3 dots, and at that time the following is performed.

The signal corresponding to each dot for smoothing is
Since it is generated from the group selection unit 50 as described above, the end of smoothing when 3 dots are required can be determined based on this signal. In the group selection unit 50, the dots to be smoothed are the dots m, (m + 1), (m
Out of +2) Is being sent. Both indicate that a smoothing period of 3 dots is required. Therefore, the OR circuit 46
If these signals are output via, the signal is generated for one dot at the smoothing start time.

By capturing this in the shift register 44 and outputting it from the second and third stages, the second dot and the third dot are output.
A signal for outputting smoothed data can be obtained for the dots as well. Since this signal is supplied to the terminal S of the selector 53 via the OR circuits 47 and 48, the data output from the 3-dot period data conversion unit 30 is output from the selector 53. Therefore,
Smoothing is performed on the dots B, C and D indicated by black circles in FIG. 7 (a).

Since the input data of the comparator 42 is the same when the dot E is displayed, the comparator 42 does not generate an output signal. Therefore, the output signal from the group selection unit 50 is masked by the AND circuit 49a and is not transmitted. For this reason, the output signal of the OR circuit 48 is at the “0” level, and therefore the data output from the scan converter 60 that has not been subjected to the smoothing process is output. Therefore, an image having an area can be displayed with uniform brightness without causing uneven brightness.

In the case of FIG. 7A, since the dots A and B have different luminances, the comparator 42 continuously outputs two dots. Therefore, 1 of the shift register 43
A signal for 2 dots can be obtained from only the output signal of the stage.
However, as shown in FIG. 7 (b), when the brightness is different between the part of the symbol A and the part of the symbol B, the boundary of the brightness is a line with no width, and in this case, the comparator 42 changes the timing of the dot B. Only when can the output signal be generated. Therefore, the output signal of the OR circuit 49 is used. If 3 dots are required, the output signal of the shift register 44 is secured for 3 dots by using the OR circuit 48.

Note that an actual image often has a luminance change represented by a normal distribution as shown in FIG. The initial smoothing detection and smoothing processing method described so far is performed when the brightness difference D in FIG. 8 is not zero, that is, when there is a brightness difference like the dots in FIG. There is a problem when using intensity modulation as a representational use.

In this case, if the threshold value of the brightness difference is a positive number n, smoothing is performed when D> n is satisfied, and the range of brightness modulation is also set according to the brightness levels of a and b in FIG. It is possible to make various brightness changes. In this case, the comparator 42 is a ROM that stores a preset value of n.
You can replace it with.

〔The invention's effect〕

As described above, according to the present invention, the brightness of the adjacent display points is controlled to make it appear as if a portion other than the actual display points is displayed. Therefore, the contour portion of the image is displayed as a smooth line. It is possible to obtain a screen that is easy to see.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a block diagram of a coordinate detecting unit, FIG. 3 is a block diagram of a modulation degree setting unit, and FIG. 4 is a diagram showing a positional relationship of each dot. 5, FIG. 5 is a block diagram of the smoothing control unit, FIG. 6 is a diagram showing modulation factor characteristics written in the luminance setting unit, FIG. 7 is a diagram showing boundaries where smoothing is performed, and FIG. 8 is a normal distribution. FIG. 9 is a diagram showing a luminance characteristic possessed, FIG. 9 is a diagram showing a screen displayed by polar coordinate display, FIG. 10 is a diagram showing a screen displayed by raster scan display, and FIG. 11 is a method for setting a modulation degree. FIG. 12, FIG. 12 is a diagram for explaining the size of a pixel, FIG. 13 is a diagram for explaining ideal coordinates and their intervals, and FIGS. 14 to 16 show luminance data of ideal coordinates. Figure 17 which shows where it is actually displayed It is a diagram for explaining a state in which up occurs. 1 ... sweep line, 3 ... reference point, 4 ... scanning line, 5 ...
... Display start point, 10 ... Coordinate detection unit, 20 ... Modulation degree setting unit, 30 ... Data conversion unit, 40 Smoothing control unit, 50 ... Group selection unit, 51 ... Clock control unit, 52 ... Luminance setting Part, 53 ... Selector, 54-56 ... Shift register.

Claims (1)

[Claims] 1. A video display device for converting a graphic in a PPI scan into a raster scan for display, and a coordinate conversion unit for sequentially converting points on a PPI sweep line into points on a raster scan line at a predetermined processing timing; The continuous three points sequentially converted on the raster scanning line by the conversion unit are sequentially arranged from the latest one to the next adjacent preceding point, the adjacent preceding point, and the current display point, of which the vertical and horizontal directions are divided at the intervals of the raster scanning line, and the current display is performed. PPI corresponding to a point
A group selection unit that sets a point located at one of the corners of a square area including a converted point that is a point on the sweep line as a group of light emitting points for the converted point, and each set by the group selection unit. A brightness setting unit that sets the light emitting point to a brightness that is inversely proportional to the distance from the converted point, and a first delay that delays the brightness output of the light emitting point corresponding to the adjacent preceding point of the brightness setting unit by one processing timing. A circuit, a second delay circuit that delays the luminance output of the light emitting point corresponding to the next adjacent preceding point of the luminance setting unit by two processing timings, and a light emitting point corresponding to the current display point of the luminance setting unit. A video display device, comprising: a luminance converter, a first delay circuit output, and a second delay circuit output, and a data conversion unit that selects the maximum output.