JPH05297819A - Picture display controller and picture display control method - Google Patents

Abstract

PURPOSE:To obtain a picture display controller in which the shape of picture is not distorted even if it is moved at a boundary between two scanning regions. CONSTITUTION:The picture display controller holds picture display position information in a second position holding means 109. A comparing means 106 detects that the output of the final line of a picture is finished, and by using the signal as a timing signal, picture display position information held in the second position holding means 109 is transferred to a first position holding means 104'. The transferred signal can be used as an interruption signal to MPU. Since a next picture position is rewritten by a timing signal indicating the finish of outputting whole line of the picture, the shape of the picture is not distorted even if a picture being present on a boundary between an upper scanning region and a lower scanning region is moved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device in which one display screen is divided into two or more scanning areas, such as an LCD (liquid crystal) display, an EL (electroluminescent) display, or a plasma display. The present invention relates to an image display control device and an image display control method used in the above.

[0002]

2. Description of the Related Art A conventionally known image display control device for displaying a small image such as a cursor on a display device composed of upper and lower screens is
When splitting the cursor into two upper and lower screens,
There is an odd-numbered frame for displaying the upper screen of the cursor on the upper screen, and an even-numbered frame for displaying the lower screen of the cursor on the lower screen (for example, JP-A-2-273786). ). In addition, in the cursor display control device, when the cursor is displayed across the upper and lower display areas, a unit for detecting whether or not the cursor is displayed across the two areas is provided.
Some display one cursor in the frame scanning period (for example, Japanese Patent Application No. 3-2403 proposed by the present applicant).
No. 29, filed on August 28, 1991). The outline of the above-mentioned invention proposed by the present applicant will be described below.

FIG. 4 is a diagram for explaining a cursor display control device in a conventional display device having upper and lower screens. In FIG. 4, the bitmap display device has, for example, an upper screen of 640 horizontal dots × 240 vertical lines and a lower screen of the same size as the upper screen, which is 640 horizontal dots × 480 vertical lines as a whole. It is one display screen consisting of. Then, in the horizontal size register 112, for example, horizontal dots “640” are set.

In the vertical line register 113, "240", which is half the number of vertical lines, is set. The vertical cursor start register 122 can store vertical lines “0” to “479” according to designation from the MPU 108. The horizontal counter 114 counts up from "0" by "1" by using the pixel clock as a clock input.
The comparator 115 compares the count value of the horizontal counter 114 with the set value of the horizontal size register 112,
When these values match, a match signal 116 is output. The coincidence signal 116 is connected to the clear input of the horizontal counter 114, and at this time, the horizontal counter 114 is cleared to "0".

The coincidence signal 116 is the vertical counter 11
It is connected to the clock input of 7 and the vertical counter 11
The value of 7 is incremented from "0" by "1".
The comparator 118 compares the count value of the vertical counter 117 with the set value set in the vertical line register 113, and outputs a match signal 119 when they match.
The match signal 119 is connected to the clear input of the vertical counter 117 and clears the vertical counter 117 to “0”. The detection circuit 106 detects whether the cursor is on the upper screen or the lower screen according to the value set in the vertical cursor start register 122.

Next, a case where the cursor does not extend over the upper and lower screens will be described. For example, the cursors whose vertical cursor lines in the vertical cursor start register 122 are at positions "0" to "223" and "240" to "479" do not span the upper and lower screens. In the case of a cursor that does not span the upper and lower screens, the data in the vertical cursor start register 122 outputs a coincidence signal 127 when the detection circuit 106 detects that the values of the vertical counter 117 coincide. This coincidence signal 127 is one of the cursor selection signals which is the timing for displaying the cursor from this line.

Match signal 12 which is the cursor selection signal
7, the cursor control circuit 107 clears the previous cursor display information. In addition, the cursor control circuit 10
7 selects a desired cursor pattern and outputs a cursor display signal 126. As shown in FIG. 4, the cursor display signal 126 as described above is generated by the mixer 131.
Entered in. On the other hand, the image information is stored in the memory control circuit 13
2 from the image storage device 133 to the mixer 13
Input to 1. Then, the image information and the cursor display signal 126 are superimposed by the mixer 131 and displayed on the bitmap display device 101.

Next, the case where the cursor extends over the upper and lower screens will be described. The detection circuit 106 detects that the vertical cursor line is between “225” and “239” based on the value of the vertical counter 117 and the value of the vertical cursor start register 122, and the cursor position extends over the upper and lower screens. Cursor selection signal 124 indicating that
Is output. In addition, the detection circuit 106 uses the cursor selection signal 12 indicating the first cursor line number on the lower screen.
5 is output.

The cursor control circuit 107 has a cursor selection signal 1 indicating the first cursor line number on the lower screen.
With 25, for example, control is performed so as to output the fifteenth cursor from the first line to the lower screen. After that, the cursor control circuit 107 counts the pixel clock, and when the number of scanning lines becomes “239” and coincides with the vertical cursor start line “239”,
The 0th line of the cursor is output to the upper screen. As a result, the scanning line "239" on the upper screen
Then, a cursor composed of scanning lines “1” to “15” on the lower screen is displayed on the bitmap display device 101. Therefore, even if the cursor is specified at a position across the upper and lower screens of the bitmap display device 101,
It is displayed in a state that it spans the upper and lower screens within one frame.

[0010]

However, in the first prior art (Japanese Patent Laid-Open No. 2-273786), the cursor is displayed in one by the odd-numbered frame and the even-numbered frame. You can only change the position once every two frames. Therefore, there is a problem in that the cursor straddling the boundary between the two scanning areas does not move smoothly when moving on the boundary line.

In the second prior art (Japanese Patent Application No. 3-240329 proposed by the present applicant), the display position of the cursor is changed every frame (every one screen display). However, there is a problem that the shape of the scanning area shifts when it moves at the boundary between the two scanning areas. For example,
The above problem will be described with reference to FIGS. 5 and 6.

FIG. 5 is a diagram for explaining a state in which the cursor moves on the boundary line between the two scanning areas. FIG. 6 is a diagram for explaining the cursor on the display screen which is composed of two scanning areas. 5 and 6, the display screen 4
1 is composed of, for example, 1024 horizontal pixels × 768 vertical lines (pixels). Upper scanning area 42 and lower scanning area 43
Are arranged adjacent to each other, and between them, there is a boundary 44 of the scanning area which divides the screen into two parts, the upper part and the lower part. However, in practice, the boundary 4 formed by these scan areas
No. 4 cannot be discerned visually. Further, the two scanning areas are simultaneously scanned about 60 to 70 times per second from the leftmost pixel of the uppermost line to the rightmost pixel of the lowermost line. The cursors 45 to 47, 47 'are composed of, for example, 16 horizontal pixels × 16 vertical lines (pixels). The cursor 45 indicates the case where the whole is in the upper scanning area 42. The cursor 46 is
The case where the whole is in the lower scanning area 43 is shown. Cursor 4
Reference numerals 7 and 47 'indicate the case where the upper scanning region and the lower scanning region are straddled.

In the case of a flat panel display, since the vertical synchronization period occupying one frame scanning time is small, if neglecting this, the scanning time for one line is 1 [S] ÷ 60 ÷ (768 ÷ 2) = 43.4 [μS]. Therefore, when the cursors 45 and 46 are entirely in the upper or lower scanning areas 42 and 43, they are displayed for 43.4 [μS] × 16 = 694 [μS]. If the cursor 47, 47 'spans the two scan areas 42, 43, the scan starts from the top line. Therefore, the cursors 47, 47 '
First, the portion of the cursor that is in the lower scanning area 43 is displayed, and the portion that is in the upper scanning area 42 is displayed at the end of the frame. Therefore, the time from the cursors 47 and 47 'being displayed in the lower scanning area 43 to the remaining portion being displayed in the upper scanning area 42 is 43.4 [μS] × (768 ÷ 2-16) = 16.0
[MS]. This time is a blank period.

Next, the cursors 47 and 47 'are moved to the lower scanning area 4 immediately after the portion corresponding to the upper scanning area 42 is displayed.
The part related to 3 will be displayed. As a result, it is perceived by the human eye as a combination of the upper scanning region 42 and the lower scanning region 43 of the next frame. When the cursors 47 and 47 'are stationary, there is no problem in the display method of the cursors 47 and 47'.
However, as shown in FIG. 5, the cursors 47, 47 ′ move on the boundary 44 of the vertical scanning regions 42, 43, for example, 4 [c
m / S] and slowly move. In this case, 1
The distance moved within the frame is 4 [cm] ÷ 60 = 0.6 [mm]. That is, as shown in FIG. 5, since the information of the cursor 47 is rewritten after the end of one frame, the information of the cursors 47-2 and 47'-2 in the upper scanning area 42 is the one before the rewriting and the cursor 47- 1,47 '
The information of -1 is the one after rewriting. For example,
When the cursor 47 moves to the left side of the drawing, the portion 47-1 in the lower scanning area 43 moves first, and the upper scanning area 42
The 47-2 portion at is visible 0.6 mm behind. Similarly, when the cursor 47 'moves to the right side of the drawing, the 47'-1 portion in the lower scanning area 43 moves first, and the 47'-2 portion in the upper scanning area 42 appears 0.6 mm behind. .
That is, when the cursors 47 and 47 'displayed on the boundaries of the vertical scanning regions 42 and 43 are moved, the deviations formed at the boundaries of the boundaries appear to be distortions of the shape.

The present invention has been made to solve the above problems, and an image display control device which does not disturb the shape of a small image such as a cursor even if it is moved at the boundary between two scanning areas. And an image display control method.

[0016]

[Means for Solving the Problems]

(First Invention) An image display control device for controlling an image displayed on a display in which a display screen for displaying bitmap information is divided into a plurality of scanning regions is superimposed on an image to be displayed on the display. Position information calculation means (110 in FIG. 1) for calculating display position information indicating the position where the small image to be displayed should be displayed, and this position information calculation means (11).
0) for holding the display position information calculated by the first holding means (104 'in FIG. 1) and the display position information held by the first holding means (104') and the image to be displayed. Comparison means for comparing scanning positions (106 in FIG. 1)
And update means (104 in FIG. 1) for updating the display position information held in the first holding means (104 ') at a timing based on the comparison result of the comparing means (106).

(Second Invention) The small image in the image display control device is composed of a cursor.

(Third invention) The comparing means (106) in the image display control device detects that the scanning position of the image to be displayed has passed the position to display the small image, and the update signal is updated by the detection signal. The means (104) is configured to update the display position information held by the first holding means (104 ').

(Fourth Invention) The updating means (104) in the image display control device is the position information calculating means (108).
Second holding means (109 in FIG. 1) for holding the calculation result of
And a transfer means (110 in FIG. 1) for transferring the position information held by the holding means (109) to the first holding means (104 ').

(Fifth Invention) The position information calculating means (110) in the image display control device is the updating means (104).
The display position information held in the first holding means (104 ') is updated by the above, and at the same time, the calculation of the next display position information is started.

(Sixth Invention) A cursor display control device for controlling a cursor displayed on a display in which a display screen for displaying bitmap information is divided into a plurality of scanning regions is provided for displaying the cursor on the screen. Cursor pattern storage means (14 in FIG. 3) and a counting means (FIG. 2) for sequentially reading out cursor patterns from the cursor pattern storage means (14) and generating a timing signal indicating that the cursor pattern data has been output. Of 1
3), first horizontal cursor position holding means (1 in FIG. 2) for holding the horizontal position of the cursor, and data held in the first horizontal cursor position holding means (1) as the timing signal (FIG. 2). 24) of the second horizontal cursor position holding means (2 in FIG. 2), and horizontal position counting means (3 in FIG. 2) for counting the horizontal position of the image to be displayed,
Detecting means (4 in FIG. 2) for detecting that the value of the horizontal position counting means (3) becomes equal to the data held in the second horizontal cursor position holding means (2), and the vertical position of the cursor. For holding the first vertical cursor position holding means (5 in FIG. 2) and second vertical cursor position holding means (5) for latching the data held in the first vertical cursor position holding means (5) by the timing signal. Figure 2
6), a vertical position counting means (7 in FIG. 2) for counting the vertical position of the image to be displayed, and the vertical position counting means (7).
The detection means (8 in FIG. 2) for detecting that the value of is equal to the data held in the second vertical cursor position holding means (6).

(Seventh Invention) In the image display control method, a display screen for displaying bitmap information is superimposed on an image to be displayed on a display having a plurality of scanning regions,
A control method for displaying a small image, wherein an area in which a small image to be displayed superimposed on an image displayed on an image display device is to be updated and stored, and the small image stored by this storing step is displayed. The timing at which the scanning position of the area to be displayed matches the scanning position of the image to be displayed is detected, and the image data to be displayed on the image display device and the image data of the small image are superimposed on the basis of the timing detected by this detection step.

(Eighth Invention) The small image in the image display control method is a cursor.

(Ninth Invention) An image display control method is characterized in that the control method described as the seventh invention is repeated.

[0025]

[Operation] The image position information from the MPU is written in the second position holding means by the write clock.
Next, the comparison means detects that the last line of the small image has been output and outputs a transfer signal. The image position information written in the second position holding means is transferred to the first position holding means by the transfer signal. After the image position information is written in the second position holding means,
In order to be transferred to the position holding means, it is necessary to finish outputting all the small image displays. Therefore, the image position information is not rewritten while the small image is displayed. That is, even a small image that moves on the boundary line between the upper scanning region and the lower scanning region will not be deformed and distorted during the movement of the small image. Even when the small image is a cursor, the same operation is performed.

After the comparison means in the image display control device detects that the last line of the small image has been output, the updating means updates the display position information held in the first holding means. .. The calculation result calculated by the position information calculation means is held in the second position holding means. Since the transfer signal from the comparison means takes a long time from when the image position information is written in the second position holding means by the MPU to when it is transferred to the first position holding means, the transfer signal is transmitted to the first position holding means. The timing of writing the data and the timing of transferring the data to the second position holding means overlap each other, and the risk of displaying an image at an abnormal position is minimized.

The horizontal position information of the cursor is written in the first horizontal cursor position holding means by the write clock. Similarly, the vertical position information of the cursor is written in the first vertical cursor position holding means by the write clock. These pieces of information are transferred to the second horizontal cursor position holding means and the second vertical cursor position holding means, respectively, by a timing signal described later. The horizontal position counting means, which represents the horizontal scanning position of the display pixel, counts up every pixel at the horizontal scanning position. The vertical position counting means, which represents the vertical scanning position of the display pixel, counts up every line.

When the detecting means detects that the value of the second horizontal cursor position holding means and the value of the horizontal position counting means match, it outputs a coincidence output signal. Further, the detection means is
When it is detected that the value of the second vertical cursor position holding means and the value of the vertical position counting means match, a match output signal is output. These coincidence output signals serve as a cursor pattern output enable signal and a signal that holds a high level for 16 lines.

The cursor pattern storage means stores a cursor pattern for displaying the cursor on the screen. Further, the counting means sequentially reads out the cursor pattern from the cursor pattern storage means and generates a timing signal indicating that the cursor pattern data has been output. This timing signal becomes the transfer signal.

As described above, since the cursor position information is transferred by the timing signal indicating that the cursor lines have been output for 16 lines, the cursor does not move during the rewriting of the cursor. That is, the cursor straddling the boundary line between the upper scanning region and the lower scanning region is not distorted due to its shape shift even when moved.

[0031]

Practical Example FIG. 1 is a schematic block diagram for explaining an embodiment for controlling the display of a cursor in the case where the upper and lower scanning regions are integrally formed into one display device. In FIG. 1, the image display control device includes a cursor and a bitmap display device 101 for displaying image information,
A screen configuration storage circuit 102 consisting of a horizontal size register and a vertical line register for constructing a bitmap.
And a cursor pattern storage circuit 103 for storing the size and shape of the cursor, and a first cursor position holding circuit 1 including a horizontal cursor start register and a vertical cursor start register for storing the cursor position.
04 'and the update circuit 10 for updating the cursor position information held in the first cursor position holding circuit 104'.
4 and a horizontal and vertical counter for generating a timing signal necessary for displaying a cursor on the bitmap display device 101.
05 and the end of the output of the last line of the cursor are detected, and the comparator circuit 106 which transfers the cursor information of the first cursor position holding circuit 104 ′ to the second cursor position holding circuit 109 by using this output signal as a transfer signal. When,
Position information including a cursor control circuit 107 for displaying a cursor to be displayed on the upper and lower screens together with image information according to the signal output from the comparison circuit 106, and an MPU (not shown) for calculating the cursor position information and controlling each circuit. And an arithmetic circuit 108.

Further, the update circuit 104 has a second cursor position holding circuit 109 for holding the calculation result of the position information calculation circuit 108 and the second cursor position holding circuit 109.
Transfer means 110 for transferring the position information held by the first cursor position holding circuit 104 '.

FIG. 2 is a block diagram specifically showing a part of the schematic block diagram in FIG. FIG. 3 is a block diagram specifically showing a part of the schematic block diagram in FIG. The first cursor position holding circuit 104 'shown in FIG. 1 holds the cursor position information 21 from the MPU by the write clock 22 and the cursor position information 21 from the MPU by the write clock 23. It is composed of a vertical cursor position register 5.

The second cursor position holding circuit 10 shown in FIG.
Reference numeral 9 denotes a horizontal cursor start register 2 for transferring and holding the cursor information held in the horizontal cursor position register 1 by a timing signal 24 described later,
Similarly, a vertical cursor start register 6 for transferring and holding the cursor information held in the vertical cursor position register 5 by a timing signal 24 which will be described later.

Timing signal generation circuit 105 shown in FIG.
Is composed of a horizontal counter 3 which counts a pixel clock 35 in the horizontal scanning direction, and a vertical counter 7 which counts an output signal 36 of each line of the horizontal counter 3.

The comparison circuit 106 shown in FIG. 1 includes a comparison circuit 4 for detecting whether the output signals of the horizontal cursor start register 2 and the horizontal counter 3 shown in FIG. 2 coincide with each other, a vertical cursor start register 6 and a vertical counter. A comparator circuit 8 for detecting whether or not the output signals of 7 match, a flip-flop 9 for outputting by a match signal output from the comparator circuit 8 and resetting the output by a timing signal 24 described later; The output signal 25 of the flop 9 (the timing signal 24 described later is 16
This timing signal 24 is a signal indicating that the output for the line has been completed, and this timing signal 24 enters the reset terminal of the flip-flop 9. Therefore, the output signal 25 holds the high level for 16 lines. ), The flip-flop 12 is reset by a timing signal 24, which will be described later, and the output signal of the flip-flop 12 enables the clock to count 4 bits of the clock output for each horizontal line and end counting. After that, it is composed of a 4-bit counter 13 which outputs a timing signal 24.

The cursor control circuit 107 shown in FIG. 1 has the flip-flop 9 and the output signal of the comparison circuit 4 shown in FIG.
AND circuit 10 that takes the logical product of the output signals of
The logical product of the flip-flop 11 that outputs the cursor pattern output permission signal 27 by the output of the D circuit 10 and the output signal of the cursor pattern output permission signal 27 and the signal 29 indicating that the cursor is on the upper screen And an AND circuit 17 for taking the logical product of the output signal of the output permission signal 27 of the cursor pattern and the signal 30 indicating that the cursor is on the lower screen,
The ND circuit 17 enables the mixing circuit 15 for mixing the cursor pattern data and the upper screen image data 31, and the AND circuit 18 enables the mixing circuit 15 for the cursor pattern data and the lower screen image data 32. And a mixing circuit 16 for mixing.

Cursor pattern storage circuit 10 shown in FIG.
3 corresponds to the cursor pattern register 14 composed of the 2-port RAM shown in FIG. 3, and the cursor pattern data 37 designated by the MPU side is written in the address 38 designated by the MPU side.
Using the count value of the 4-bit counter 13 as an address, the pattern data is read out, and the mixing circuits 15 and 1 are read.
6 input signal.

The operation of this embodiment will be described with reference to FIGS. 2 and 3, the horizontal position information of the cursor is stored in the MP (not shown) by the rising edge of the write clock 22 via the data bus 21.
Write from U to Horizontal Cursor Position Register 1. Similarly, the vertical position information of the cursor is written in the vertical cursor position register 5 via the data bus 21 at the rising edge of the write clock 23. These pieces of information are transferred to the horizontal cursor start register 2 in the second stage and the vertical cursor start register 6 in the second stage at the rising edge of the timing signal 24 described later. Since the timing signal 24 is the most important point in the present invention, it will be described in detail later.

The horizontal counter 3 representing the horizontal scanning position of the display pixel counts up for each pixel at the horizontal scanning position. The vertical counter 7 representing the vertical scanning position of the display pixel is
Count up every line. When the comparison circuit 4 detects that the value of the horizontal cursor start register 2 and the value of the horizontal counter 3 match, the comparison circuit 4 becomes a high level as a match output signal. This high level signal is the AND circuit 1
It becomes one input of 0.

Further, when the comparison circuit 8 detects that the value of the vertical cursor start register 6 and the value of the vertical counter 7 match each other, it becomes a high level as a match output signal. This high level signal sets flip-flop 9. The flip-flop 9 remains set until the timing signal 24 becomes high level, that is, for 16 lines, and holds its output signal 25 at high level. Similarly, the horizontal counter 3 representing the horizontal scanning position of the display pixel is counted up for each pixel.
When the comparison circuit 4 detects that the value of the horizontal cursor start register 2 and the value of the horizontal counter 3 match, the comparison circuit 4 becomes a high level as a match output signal.

Since the high-level signals output from the respective comparison circuits 4 and 8 are logically ANDed by the AND circuit 10, the flip-flop 11 is operated only for 16 lines after the horizontal position of the cursor coincides. set. The output permission signal 27 of the flip-flop 11 is a cursor pattern output permission signal indicating that the cursor pattern may be mixed with the image data. Flip flop 1
1 is a signal 2 which goes high 16 pixels after the cursor pattern output permission signal 27 goes high
Reset by 6. The signal 26 is generated by a counter (not shown) that counts the number of horizontal pixels of the cursor pattern.

The output signal 25 sets the flip-flop 12. As a result, the flip-flop 12
Is connected to the enable terminal of the 4-bit counter 13 to enable the 4-bit counter 13. The 4-bit counter 13 starts counting up from the initial value 0 by the clock 28 that goes high every line. The 4-bit counter 13 outputs a high-level timing signal 24 from its overflow terminal OV when its value changes from 15 to 0 in decimal notation. When the timing signal 24 becomes high level,
Since the flip-flop 9 shown in FIG. 2 is reset, the output signal 25 becomes low level. In addition, the above 16
Timing signal 2 indicating that the output for the line is completed
As described above, 4 indicates the values of the horizontal cursor position register 1 and the vertical cursor position register 5 by using the horizontal cursor start register 2 and the vertical cursor start register 6 respectively.
Transfer to.

At the same time, when the timing signal 24 becomes high level, the flip-flop 12 is reset, so that the 4-bit counter 13 stops counting up. That is, the timing signal 24 becomes high level 16 lines after the comparison circuit 8 outputs the coincidence output signal. The output of the 4-bit counter 13 is 16 bits x 1
It is connected to the address input of a 6-word cursor pattern register 14. This cursor pattern register 1
4, an address “0” of the cursor has a bit pattern of the first line of the cursor, an address “1” has a bit pattern of the second line of the cursor ,. ． ． The bit pattern of the 16th line of the cursor is stored in the address “15”. Therefore, the image data mixing circuit 1
The cursor patterns are sequentially supplied to 5 and 16 from the first line.

The output permission signal 27 of the cursor pattern is
It is connected to one input of the AND circuits 17 and 18.
The signal 29 connected to the other input of the AND circuit 17
Is a signal indicating that the cursor is in the upper scanning area. Therefore, the mixing circuit 15 has the AND circuit 17 described above.
The output signal causes the enable state. As a result, the mixing circuit 15 mixes the upper screen data 31 and the cursor pattern from the cursor pattern register 14 and outputs the image data 33. This image data 33 is
When supplied to a flat panel display, a cursor is displayed with the image in the upper scan area.

Similarly, the signal 30 connected to one input of the AND circuit 18 is a signal indicating that the cursor is in the lower scanning area. Therefore, when the cursor is in the lower scanning area and the output permission signal 27 of the cursor pattern becomes high level, the mixing circuit 16 is enabled by the output signal of the AND circuit 18. As a result, the mixing circuit 16 mixes the lower screen image data 32 and the cursor pattern from the cursor pattern register 14 and outputs the image data 34. This image data 3
When No. 4 is supplied to the flat panel display, the cursor is displayed in the lower scanning area together with the image. As described above, the cursor is always displayed from the first line and is continuously displayed for 16 lines, so that the shape does not appear distorted even if it extends over the upper and lower scanning regions.

Here, the timing signal 24 will be supplementarily described. Generally, the clock that supplies image information to the display device and the operation clock of the MPU are asynchronous. That is, the timing of counting up the horizontal counter 3 indicating the horizontal scanning position and the timing 22 of rewriting the horizontal cursor position register 1 by the MPU are asynchronous. The timing at which the vertical counter 7 indicating the vertical scanning position is counted up and the timing at which the MPU rewrites the vertical cursor position register 5 are asynchronous. Further, when the MPU rewrites the horizontal cursor position register 1 and the vertical cursor position register 5, it is impossible that all the bits change from the previous value to the new value at the same time and in an instant. Therefore, when the MPU rewrites the horizontal cursor position register 1 and the vertical cursor position register 5, the means for detecting the coincidence of the values of the horizontal cursor position register 1 and the horizontal counter 3 and the vertical cursor position register 5 and the vertical counter 7 is temporarily operated. , Or the horizontal cursor position register 1 and the vertical cursor position register 5 have a two-stage buffer structure,
MP synchronized with the count-up clock of the counter
Data must be transferred to the second-stage register at a timing when U does not rewrite the first-stage register.
If the above is not done, the cursor may be momentarily displayed in a place where it should not be displayed.

If the means 4 or 8 for detecting the coincidence is temporarily disabled at the timing when the horizontal cursor position register 1 is rewritten by the MPU or the timing when the vertical cursor position register 5 is rewritten, the cursor may flicker. Therefore, the register has a two-stage buffer structure,
The cursor data is transferred, for example, from the horizontal cursor position register 1 to the second horizontal cursor start register 2. This transfer clock uses a timing signal 24 indicating that the cursor has been output for 16 lines. The timing signal 24 can also be used as an interrupt signal to an MPU (not shown). That is, when the timing signal 24 becomes high level, the MPU rewrites the data of the horizontal cursor position register 1, the vertical cursor position register 5 and the cursor pattern register 14.

If the transfer signals of the horizontal cursor start register 2 and the vertical cursor start register 6 and the write clocks 22 and 23 have the same timing, the cursor display may be strange. If the rewriting timing of the cursor pattern register 14 and the output timing of the cursor pattern overlap, the shape of the cursor pattern may be disturbed. Therefore, the timing signal 24 interrupts the MPU immediately after the cursor pattern on the 16th line is output so that the MPU can maximize the time margin until the end of the rewriting of data in these registers, and at the same time, the horizontal cursor The values of the position register 1 and the vertical cursor position register 5 are transferred to the horizontal cursor start register 2 and the vertical cursor start register 6.

Although the present embodiment has been described in detail above, the present invention is not limited to this embodiment. Various design changes can be made without departing from the invention described in the claims. For example, in the present embodiment, the display screen is described as being vertically divided into two and scanned, but the present invention is not limited to this. In general, the same applies to the case where scanning is performed by being divided into k (k is a natural number of 2 or more) screens. The size of the display screen is 1024 pixels × 768 lines, but the size is not limited to this, and generally n pixels × 768 pixels.
m lines (n and m are natural numbers) may be used. Further, the size of the cursor has been described as 16 pixels × 16 lines, but the size is not limited to this, and may be generally i pixels × j lines (i and j are natural numbers) or a pattern indicating an arrow. good.

Some flat panel displays require a plurality of dummy lines in the vertical synchronization period, and some do not. In the present embodiment, the description is given of the case where no dummy line is required, so that the cursor is always continuously output for 16 lines. If a dummy line is required, the clock 28 of the 4-bit counter 13 may be set so as not to be high level during the dummy line period. As a result, the cursor is not continuously output when it extends over the upper and lower scanning areas. However, while there are several dummy lines, there are several hundred lines until the cursor is next displayed. Therefore, the shape of the cursor is distorted and cannot be seen.

In this embodiment, the horizontal position of the display pixel is described as being counted by the horizontal counter 3 for each pixel, but the present invention is not limited to this, and for example, 2 pixels, 4 pixels or Like every 8 pixels,
You may count for every several pixel. In this case, the horizontal cursor start register 2 is correspondingly set with a value indicating the cursor position for each of a plurality of pixels, and the deviation for each pixel from that position to the actual start position of the cursor is illustrated as an offset value. Not set by the mechanism. Furthermore, although the 4-bit counter 13 is described as counting up from 0, the 4-bit counter 13 is not limited to this and counts from other numbers in relation to the data stored in the cursor pattern register 14. It may be up, or may be configured as a down counter.

[0053]

As described above, according to the present invention, 2
On a screen that is divided into three or more areas and scanned, the display position information of the small image is updated immediately after the small image to be superimposed on the image to be displayed on the screen has finished outputting the displayed scan line. Since the next display position information is written, there is an effect that even if the small image is moved over different scanning areas, the shape of the small image does not shift and does not appear distorted. In addition, since the calculation start signal for the position of the small image is used as the signal indicating that the output of the small image is completed, the calculation is completed by the time the next small image is output, so that the small image is located at an abnormal position. It is never displayed. Furthermore, since the signal indicating that the output of the small image has ended is the rewriting start signal of the display position information, the display position information can be rewritten by the time the next small image is output.
The small image is not displayed in an abnormal position.

[Brief description of drawings]

FIG. 1 is a schematic block configuration diagram for explaining an embodiment for controlling display of a cursor in the case where vertical scanning regions are integrally configured to form one display device.

FIG. 2 is a block configuration diagram specifically showing a part of the schematic block configuration diagram in FIG.

FIG. 3 is a block configuration diagram specifically showing a part of the schematic block configuration diagram in FIG. 1.

FIG. 4 is a diagram for explaining a cursor display control device in a conventional display device having upper and lower screens.

FIG. 5 is a diagram for explaining a state in which a cursor moves on a boundary line between two scanning areas.

FIG. 6 is a diagram for explaining a cursor on a display screen including two scanning regions.

[Description of Reference Signs] 101 ... Bitmap display device 102 ... Screen configuration storage circuit 103 ... Cursor pattern storage circuit 104 ... Update circuit 104 '... First cursor position holding circuit 105 ... Timing signal generation circuit 106 ... Comparison circuit 107 ... Cursor control circuit 108 ... Transfer means 109 ... Second cursor position holding circuit 110 ... Position information calculation circuit 1 ... Horizontal cursor position register 2 ... Horizontal cursor start register 3 ... Horizontal counter 4 ... Comparison circuit 5 ... Vertical cursor position register 6 ... Vertical cursor start register 7 ... Vertical counter 8 ... Comparison circuit 13 ...・ 4 bit counter 14 ・ ・ ・ Cursor pattern register 15 ・ ・ ・ Mixing circuit 16 ・ ・ ・ Mixing circuit

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location G09G 5/36 9177-5G

Claims (9)

[Claims] 1. An image display control device for controlling an image displayed on a display in which a display screen for displaying bitmap information is divided into a plurality of scanning areas, the image display control device being superimposed on the image to be displayed on the display. Position information calculation means for calculating display position information indicating the position where the small image to be displayed is displayed, first holding means for holding the display position information calculated by this position information calculation means, and this first Comparing means for comparing the display position information held in the holding means with the scanning position of the image to be displayed, and the display position information held in the first holding means at a timing based on the comparison result of the comparing means. An image display control device comprising: an updating unit that updates the. 2. The image display control device according to claim 1, wherein the small image is a cursor. 3. The comparing means detects that the scanning position of the image to be displayed has passed the position to display the small image, and the detection signal causes the updating means to update the first image.
The image display control device according to claim 1, wherein the display position information held in the holding means is updated. 4. The updating means includes second holding means for holding the calculation result of the position information calculating means, and transfer means for transferring the position information held by the holding means to the first holding means. The image display control device according to claim 1, further comprising: 5. The position information calculation means starts the calculation of the next display position information at the same time when the display position information held in the first holding means is updated by the updating means. The image display control device according to claim 1. 6. An image display control device for controlling a cursor displayed on a display in which a display screen for displaying bitmap information is divided into a plurality of scanning areas, and a cursor pattern storage for displaying the cursor on the screen. Means, a counting means for sequentially reading out the cursor pattern from the cursor pattern storage means, and generating a timing signal indicating that the cursor pattern data has been output, and a first horizontal cursor position holding means for holding the horizontal position of the cursor. Means, second horizontal cursor position holding means for latching the data held in the first horizontal cursor position holding means by the timing signal, horizontal position counting means for counting the horizontal position of the image to be displayed, The value of the position counting means is held in the second horizontal cursor position holding means. Detection means for detecting that the data has become equal to the stored data, first vertical cursor position holding means for holding the vertical position of the cursor, and data held in the first vertical cursor position holding means for the timing signal. Second vertical cursor position holding means for latching by, vertical position counting means for counting the vertical position of an image to be displayed, and data of the value of the vertical position counting means held in the second vertical cursor position holding means An image display control device comprising: a detection unit that detects equality. 7. An image display control method for displaying a small image by superimposing it on an image to be displayed on a display in which a display screen for displaying bitmap information is divided into a plurality of scanning areas. The area for displaying the small image to be displayed superimposed on the image displayed in is updated and stored, and the scanning position of the area for displaying the small image and the scanning position for the image stored by this storing step match. An image display control method comprising detecting timing and superimposing image data to be displayed on an image display device and image data of a small image on the basis of the timing detected by the detecting step. 8. The image display control method according to claim 7, wherein the small image is a cursor. 9. An image display control method, characterized in that the control method according to claim 7 is repeated.