JP2000098996A - Image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To instantly change the overlapping state of respective windows in an image display device performing a multi-window display. SOLUTION: This image display device provided with a multi-window display means for setting the window being plural rectangular areas in a display picture of a display device 9 and respective displaying image information stored in a plural image memory areas in respective plural windows is provided with a display control circuit 4 for controlling the display contents by performing mask processing for expressing the overlapping state of respective windows displayed on the display picture synchronized with display operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display device using a CRT (cathode ray tube), an LCD (liquid crystal display), or the like.

[0002]

2. Description of the Related Art Conventionally, as an image display device, image data stored in a VRAM is sequentially read out, and a CRT or an LC is read.
A display device using D or the like includes a graphic display device that displays image information such as characters and patterns.

In this type of image display device, a so-called window display is conventionally used as a method of switching display contents and expanding a screen. This window display
A rectangular area is set in the screen to display image information stored in a completely different image memory area (hereinafter referred to as "layer"). Among them, multi-window display in which a plurality of rectangular areas are set is common. It has become.

A method for performing multi-window display includes a software method in which data in a frame buffer for storing displayed image information is rewritten, and another image information is drawn in the area. There is a method of setting mask data and controlling the drawing area in hardware.

[0005] In the case of a software method, in addition to a VRAM necessary for storing all image information including an image of a portion where each window is not displayed, the same image information as the displayed image is held. Are provided.

In the case of a hardware method, image information for drawing all images is stored in a VRAM, and a multi-window display is performed by performing hardware mask processing of a portion where each window overlaps.

[0007]

However, when a window is displayed by a software method, the image information to be displayed must be restored each time the overlapping of the windows is changed. Had to be transferred to the frame buffer again. This transfer process has been a factor in slowing down the drawing speed when changing the screen.

[0008] Among the hardware methods, the method of rewriting the mask data in the overlapping portion of each window is as follows.
There is a drawback that the circuit constituting the mask data becomes enormous in scale as the number of windows increases.

In view of the above, the present invention has been made to solve such a problem, and has a so-called multi-window display in which a plurality of windows are set in a display screen and image information stored in a plurality of layers is displayed. It is an object of the present invention to make it possible to immediately change the degree of overlap between windows in an image display device.

[0010]

In order to solve the above-mentioned problems, the present invention sets a plurality of rectangular windows on a display screen, and stores image information stored in a plurality of image memory areas. In an image display apparatus having multi-window display means for displaying in a plurality of windows, display processing is performed by performing a mask process for expressing an overlap between windows displayed on the display screen in synchronization with a display operation. And a display control means for controlling the image display device.

The display control means has at least a mask calculator and an effective layer controller, and outputs image information stored in an image memory area corresponding to the effective information output by the effective layer controller. The mask arithmetic unit may perform the mask processing for preventing the image information stored in the image memory area from being displayed.

The display control means has at least a mask calculator, a window attribute register, a window attribute switch, and an effective layer controller, and an image memory area corresponding to the effective information output by the effective layer controller. The mask arithmetic unit performs a mask process for outputting the image information stored in the window attribute register so as not to display the image information stored in the other image memory areas, and stores the mask information in the window attribute register. Preferably, the attribute information is changed by the window attribute switch to change the shape of the window.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the main configuration inside the image display device of the present invention, and FIG. 2 is a block diagram showing the entire configuration inside the device.

The image display device, as shown in FIG.
U1, ROM 2, timing generator 3, display control circuit 4, bus driver 5, multiplexer 6, VRAM (video RAM) 7, latch circuit 8,
It comprises a LUT (logical unit table) 20 and a display device 9, and further includes a display start address (start address) for accessing the VRAM 7, and the number of display characters in the horizontal direction on the display screen of the display device 9 (horizontal). A register (not shown) for setting the display screen width) is also provided.

The CPU 1 is a central processing unit for controlling the entire image display device, and executes processing according to a predetermined program. Then, the display start address on the VRAM 7 and the LC
The number of characters to be displayed in the horizontal direction of the D screen, the number of characters to be written in the VRAM 7 in the horizontal direction, and the like are set.

The ROM 2 is a read-only storage device, which stores not only programs to be processed by the CPU 1 but also graphic pattern data to be displayed on the display device 9.

The timing generator 3 includes a display device 9
It generates various synchronization signals required for the screen display of
It is connected to the CPU 1, the display control circuit 4, the bus driver 5, the multiplexer 6, and the latch 8 circuit.

The display control circuit 4 has a data bus (D0-1).
5) and the multiplexer 6 via the graphic display address bus 10.
It is connected to the.

The display control circuit 4 controls the CPU according to the timing signal generated by the timing generator 3.
1 has a function of repeating a cyclic display operation asynchronously. And, in order to display regularly,
The display control circuit 4 has a priority in accessing the VRAM 7 as a display memory. The timing generator 3 controls the multiplexer 6 so that the display data is rewritten or read by the CPU 1 at the timing when the display control circuit 4 is in the non-access state.

As shown in FIG. 1, the display control circuit 4 includes a main scanning counter 11, a sub-scanning counter 12, a window attribute register 13, a priority register 14, an effective layer controller 15, a window attribute switch 16, a mask operation. And an address output unit 18.

Main scanning counter 11 and sub-scanning counter 1
2 sets the display position of the data to be displayed on the display screen of the display device 9 as shown in FIG.
The former defines the coordinates in the main scanning direction (horizontal direction in the drawing), and the latter defines the coordinates in the sub-scanning direction (vertical direction in the drawing).

The window attribute register 13 stores the attributes of each window displayed on the display screen. Window attributes include the origin coordinates of the window display position,
There are end point coordinates, virtual screen width, and address offset values (addresses of the origin data of each window on the VRAM 7). In the window attribute register 13, a plurality of registers for setting the origin and end point coordinates and a virtual screen width are set. There are a plurality of registers for setting the address offset value and a plurality of registers for setting the address offset value.

The priority register 14 stores priority information for setting the display order of each window displayed on the display screen. The effective layer controller 15 determines the only layer that stores the image information of the window displayed at the top when a plurality of windows overlap, and outputs valid information for specifying the layer.

The window attribute switch 16 changes the size and display position of the window on the display screen by appropriately switching the attribute of each window displayed on the display screen. In other words, the window attribute corresponding to the valid information output from the valid layer controller 15 is extracted from the window attribute register 13 and output to the mask calculator 17.

The mask calculator 17 executes a mask process for expressing the overlap of windows displayed on the display screen based on various kinds of input information. The address output unit 18 outputs a display address for specifying the image information stored in the frame buffer in the VRAM 7.

The bus driver 5 shown in FIG. 2 controls the data buses (D0 to D15). The bus driver 5 is connected to the CPU 1 and the display control circuit 4 via the data bus, and is also connected to the VRAM 7. I have. Multiplexer 6
Executes a process of selecting access to the VRAM 7 from the CPU 1 and the display control circuit 4. It is also connected to CPU 1 and ROM 2 via an address bus.

The VRAM 7 is a memory for storing image information such as characters and figures to be displayed on the display device 9.
Image information corresponding to the designated address can be taken out. Then, the extracted image information is transferred to the display device 9 via the latch circuit 8 and the LUT 20.

The display device 9 has a display screen for displaying image information stored in the VRAM 7. A plurality of windows can be displayed on this display screen in addition to the basic display screen. The display device 9 is a CRT, LCD
Alternatively, a display device capable of two-dimensional display of other characters and figures may be used.

Next, a specific operation of the image display device will be described. This image display device corresponds to the ROM 2 of FIG.
Operates according to the processing program stored in the CPU 1 as follows.

First, the CPU 1 transfers image information to be displayed to an area defined by a predetermined address of a frame buffer in the VRAM 7. The image information is sent to the address output unit 18 of the display control circuit 4 shown in FIG. 1 according to the frame synchronization signal generated by the timing generator 3.
Are read from the VRAM 7 and output in accordance with the graphic display address output on the graphic display address bus 10. The output image information is transferred to the display device 9 via the latch circuit 8 and the LUT 20, and displayed on the display screen.

As described above, the CPU 1 shown in FIG. 2 displays the image information, and at the same time, sets a plurality of rectangular areas, that is, a plurality of windows in the basic screen, and displays the image information stored in another layer. Processing shall be executed.

In this process, first, the CPU 1 sets a start address of the basic screen, a horizontal display screen width, a basic screen width, and the like in order to display the basic screen. Then, the mask calculator 17 of FIG. 1 calculates and outputs the display address for the basic screen based on these and the output values of the main scanning counter 11 and the sub-scanning counter 12.

When the CPU 1 displays each window, the CPU 1 sets attribute information indicating the attribute of each window to be displayed in the window attribute register 13. in this case,
The attributes to be set include the virtual screen width Wm on the VRAM 7.
n, the coordinates of the origin of the display position (Wsxn, Wsyn) and the coordinates of the end point (Wexn, Weyn) are set independently, and the address offset Awsn of the layer corresponding to each window is set. The CPU 1 sets priority information in the priority register 14 before and after this. By setting the priority information, the display order of each window to be displayed on the display screen of the display device 9 can be set in advance.

During the execution of the display process, the main scanning counter 11 and the sub-scanning counter 12 output coordinate information for setting the display position. Then, based on the coordinate information, the attribute information of each window, and the priority information stored in the priority register 14, the effective layer controller 15 determines a single layer (the highest layer among the overlapping windows). It outputs valid information for validating a layer for storing image information displayed in the window. The valid information includes an address for specifying a unique layer and the attribute information of the corresponding window, and is sent to the window attribute switch 16 when output.

When the window attribute switch 16 receives the valid information from the valid layer controller 15, the window attribute register 13 displays the image information in the topmost window from the window attribute register 13 so as to display the layer information corresponding to the window to be displayed. The mask calculator 17 converts the address and the attribute information.
Output to

The mask arithmetic unit 17 performs the following arithmetic processing for each coordinate corresponding to the output of the main scanning counter 11 and the sub-scanning counter 12 in synchronization with the above-described basic screen display processing by the CPU 1. This is a masking process performed in synchronization with the screen display process with reference to the address of the received valid information and its attribute information. That is, the image information of the layer corresponding to the address is output to the corresponding window of the display device 9, while the other image information is subjected to arithmetic processing so as not to be output, and is displayed in the lower window. The image information to be performed is not displayed on the screen.

As described above, the mask computing unit 1 is synchronized with the display processing of the basic screen for displaying image information by the CPU 1.
7 operates, and the VRAM 4 corresponds to the display address of the only layer received from the effective layer controller 15.
The corresponding image information is picked up from the display data of each window stored in. Thus, a multi-window screen is obtained.

Next, the case where the display shape of each displayed window is changed will be described. This can be performed by changing the origin coordinates and the end point coordinates of the window attribute register 13. Can be done without changing information. This is because when changing the display shape of the window, it is not necessary to change the contents of the image displayed in the window, and the display position of the window can be changed accordingly by changing the origin coordinates and the end point coordinates.

When scrolling the display of image information in the window, the address offset value Awsn of the window attribute register 13 may be changed. In the above embodiment, the case where the present invention is applied to an LCD controller of an image display device has been described as an example. Needless to say, it can be applied to

[0040]

According to the image display apparatus of the present invention, in so-called multi-window display, mask data for expressing the degree of overlap of individual windows to be displayed is generated in synchronization with the display operation, and display control is performed. it can. For this reason, by setting the degree of overlap of each window using the priority information corresponding to the order in which the windows overlap, it is possible to arbitrarily set the display shape of the window without changing the image information in the VRAM. it can.

Therefore, in order to change the vertical relationship of each window, it is sufficient to change the priority information.
There is no need to change the above image information. In order to change the display position and size of the window, the display position coordinates (origin, end point) of the corresponding window may be changed. Therefore, the vertical relationship of each window can be changed, and the display position and size can be changed quickly, and all means for changing the display state of the multi-window screen can be quickly performed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a relationship between a portion according to the present invention of a display control circuit 4 and a VRAM 7 and a display device 9 in FIG.

FIG. 2 is a block diagram showing an internal configuration of an embodiment of the image display device according to the present invention.

FIG. 3 is a diagram showing an example of a window display on a display screen.

[Explanation of symbols]

1: CPU 2: ROM 3: Timing generator 4: Display control circuit 5: Bus driver 6: Multiplexer 7: VRAM 8: Latch circuit 9: Display device 10: Display address bus 11: Main scanning counter 12: Sub scanning counter 13: Window attribute register 14: Priority register 15: Effective layer controller 16: Window attribute switch 17: Mask calculator 18: Address output unit

Claims (3)

[Claims] 1. A multi-window display means for setting a plurality of rectangular windows on a display screen and displaying image information stored in a plurality of image memory areas in each of the plurality of windows. An image display device, comprising: a display control unit that controls display contents by performing a mask process for expressing an overlap between windows displayed on the display screen in synchronization with a display operation. Display device. 2. The display control means includes at least a mask calculator and an effective layer controller, and outputs image information stored in an image memory area corresponding to the effective information output by the effective layer controller. 2. The image display device according to claim 1, wherein the mask calculator performs a mask process for preventing display of image information stored in an image memory area other than the image information. 3. The display control means includes at least a mask calculator, a window attribute register, a window attribute switch, and an effective layer controller, and an image memory area corresponding to the effective information output by the effective layer controller. The mask arithmetic unit performs a mask process for outputting the image information stored in the memory unit and not displaying the image information stored in the other image memory areas. 2. The image display device according to claim 1, wherein the shape of the window is changed by changing the attribute information by the window attribute switch.