JPH0345994A - Image display device - Google Patents

Abstract

PURPOSE:To obtain the composition effect between two images by after-image effect by projecting the images on a display device from an image storage means alternately through a display control means in synchronism with frames and rasters. CONSTITUTION:A triangular image is stored on an image memory 1, a circular image is stored on an image memory 2, and the stored images of pieces of image output information 1O and 2O are the same. Here, an image 5e is dis played on a display device 5 in even frames for operation and an image 5O is displayed in even frames. Those images 5e and 5O are alternated, frame by frame. The frame period is 30 - 60 Hz on a general raster type display device and frequently 60 Hz on a display device whose flicker is inconspicuous. Consequently, images are displayed alternately at a 60 Hz period. Consequently, the images 5e and 5O are seen as their composite image 5m to the human eye because of the after-image effect.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to displaying overlapping images in an image display device.

[Summary of the invention]

The present invention solves the problem of displaying image data stored in image memories divided into separate areas in an overlapping manner on a raster-type image display device in an image display device. Outputs image data at an even vertical address, and outputs image data at an odd vertical address in another image memory 2 in the case of an odd numbered rask;
And by outputting the opposite for odd frames,
A composite image is displayed on a display device using the afterimage effect of the human eye.

[Conventional technology]

Conventionally, methods for displaying superimposed images include a memory division method shown in FIG. 3 ial and a brightness addition method shown in FIG. 3 tb). In the former memory partitioning method, Figure 3 (a
By dividing the image memory 31 into an image memory 31a and an image memory 31b as shown in FIG.
A composite image is created using a brightness conversion table 32 and displayed on a display device 34 via a D/A converter 33.

In the latter luminance addition method, as shown in FIG.
After converting the brightness using 8, a brightness adder 39 converts the resulting image into a composite image, which is then displayed on a display device 41 via a D/A converter 40.

[Problem to be solved by the invention]

In the conventional method, for example, in the superimposed display using the memory division method, the memory plane is divided according to the brightness direction, so in the case of multi-color expression, there is a drawback that the expressed colors become small. In addition, when there are many expression colors, the high-speed brightness conversion table becomes large and the circuit becomes large. On the other hand, the superimposed display using the brightness addition method has the disadvantage that the brightness conversion table is doubled, the number of signals between the brightness conversion table and the image memory increases, and a high-speed synthesis circuit is required.

[Means to solve the problem]

In order to solve these problems, the present invention includes an image storage means for storing at least two or more screens of images, a display control means for extracting image data from the image storage means and displaying it on a display device, and a raster type display device. An image generating means for generating and storing an image in the image storing means, and a signal synchronized with the frame and raster of the display screen of the display device generated by the display controlling means to alternately output the image data of the image storing means. The present invention provides an image display device for displaying a composite image of images on two or more screens.

[Effect]

In the present invention, the display control means gives a display timing to the display device, the image storage means takes out the image storage data, and the switching means takes out the image data from the image storage means when the frame of the display screen is an even frame and an even raster; For odd-numbered rasters, image data is retrieved from the other image storage means and repeated sequentially; for odd-numbered frames, image data is retrieved from the image storage means for even-numbered frames, and for odd-numbered rasters, image data is retrieved from the image storage means for odd-numbered frames, in the reverse order of the even-numbered frames. Image data is retrieved from the image storage means and sequentially repeated, and in this way, the image data is alternately displayed on the display device via the display control means in synchronization with the frame and raster from the image storage means and the image storage means. The screen displayed at this time changes frame by frame, but to the human eye it appears as if two images have been combined due to the afterimage effect.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows an embodiment of the present invention, in which an image memory 1 is an image memory that stores image data for displaying images on a display device 5. As shown in FIG. Image memory 2 is the same as image memory 1.0 In this embodiment, image memory 1 and image memory 2 are physically separated, but they are the same memory and can be divided into image memory 1 and image memory 2 by address area. It may be an image memory consisting of a memory that distinguishes between different types of images.

That is, it is not necessary to have two image memories 1 and 2, and they may be memories that can be separated by address space.The outputs of the image memories 1 and 2, that is, image data, are connected to the switching circuit 3.In this embodiment, the switching circuit 3 The connections between image memories 1 and 2 are separately connected, but they may be shared by a logical connection to wired O. In this case, image memories 1 and 2 are connected separately.
Although they may be activated at the same time, usually either image memory 1 or image memory 2 is activated.

Now, the switching circuit 3 selectively extracts the image data output from the image memory 1 or 2 using the signals 4a and 4b output from the display control circuit 4, and transfers the image data of the image memories 1 and 2 to the display control circuit 4. The output 0 display control circuit 4 has a function of generating display timing for horizontal synchronization and vertical synchronization on the raster type display device 5, and is further configured to display on a predetermined raster in synchronization with the display timing. It also has a function of generating display memory addresses 4a for the image memories 1 and 2 and the switching circuit 3. The memory address 4a consists of a horizontal address corresponding to the horizontal starting point of the display device and a vertical address corresponding to the raster of the display device. It also has a function of generating a signal corresponding to the vertical period of the display device 5, that is, a frame signal 4b. This frame signal indicates an even frame state when the screen of the display device 5 is in an even-numbered screen display period (this is called an even frame), and when the screen of the display device 5 is in an odd-numbered screen display period (this is called an odd frame). (call) indicates an odd frame state.

The last function of the display control circuit 4 is to convert the image data sent from the switching port IS3 into a brightness signal using a brightness conversion table, and then convert it into an analog signal and display it as a brightness signal (also called a video signal) on the display device 5. Output to device 5.

The display device 5 is a raster type display device, and images are displayed on a CRT to the human eye.

The image generation circuit 6 is a circuit that generates and writes images to the image memories 1 and 2, and the 0 image generation circuit 6 connected by at least an image memory address signal, an image data signal, and a write control signal is a circuit according to the present invention. Since this is not a basic element, further explanation will be omitted.

Now, referring to FIG. 1, a simple operation of the present invention will be explained.

The display control circuit 4 outputs a memory address signal 4a and a frame signal 4b. The image memory 1 outputs the memory contents at the address, that is, image data, in response to the memory address signal 4a and the frame signal. Image memory 2 also operates in the same way as image memory 1. Each image data is sent to the switching circuit 3, and if the frame signal 4b is an even frame and the lowest vertical address signal 4aυ0 of the memory address signal 4a is 0, the switching circuit 3 selects an even raster address. As shown in the figure, at this time, the switching circuit 3 sends the image data in the image memory 1 to the display control circuit 4.

Lowest signal 4 of vertical address of memory address signal 4a
If aυ0 is 1, it indicates an odd raster address, but in this case, the switching circuit 3 continues the six or more operations of sending the image data in the image memory 2 to the display control circuit 4 until the even frame state ends. It will be done.

When the frame signal 4b becomes an odd frame state, the switching port t
m3 sends the image data of the image memory 2 to the display control circuit 4 when the lowest signal 4aυ0 of the vertical address is 0, and the image data of the image memory 1 when 4aυO is 1.

This operation also continues during the odd frame state. In this way, the image data in image memories 1 and 2 can be alternately displayed on the display device. The operation of the switching circuit 3 described above is shown in a table to make it easier to understand.

Now, how to display an image on the display device 5 will be explained based on FIG. A triangular image like le in FIG. 2 is stored in the image memory l in FIG. 1, and the image memory 2
It is assumed that a circular image such as 2e in FIG. 2 is stored in . The stored images of lo and 2o are the same. Here, in the case of an even number frame, the operation is performed as shown in the table above, so that an image as shown in 5e is displayed on the display device 5.

Further, in odd-numbered frames, an image as shown in 5o is displayed. The images 5e and 5o are alternately switched for each frame. This frame period is 3011z to 6011z in a general raster type display device. 6011z is often used in display devices where flicker is not noticeable, and as a result, the 5e video and the 50 video are alternately displayed at a cycle of 60 Hz. Then, due to the afterimage effect, 5e appears to the human eye.
The result is a composite image of 50 and 50 meters, that is, a 5-meter image.

In Fig. 1, the image data of image memories 1 and 2 are led to the switching circuit 3 and switched alternately by the switching circuit 3, but instead of the switching circuit 3, the outputs of the image memories 1 and 2 are wired to 0. It can also be realized by logical connections. In this case, image data output may be activated on the image memories 1 and 2 as shown in the table above. In addition, if image memories 1 and 2 are realized by the same memory, the same effect can be obtained by arranging the address space in the image memory 1 part and the image memory 2 part and outputting the image data from the predetermined address as shown in the table above. can be realized.

〔Effect of the invention〕

As explained above, according to the present invention, there is no restriction on expressed colors as in the conventional image memory plane division method, there is no increase in the luminance conversion table as in the luminance addition method, and a high-speed synthesis circuit is possible. It is possible to display images in a superimposed manner without the need.

[Brief explanation of drawings]

Fig. 1 is a detailed explanatory diagram of the present invention, Fig. 2 is a detailed explanatory diagram of the present invention, Fig. 3 Tal is an explanatory diagram of superimposed display using the memory division method, and Fig. 3 1b) is a superimposed display using the luminance addition method. It is an explanatory diagram. 1... Image memory 1e... Image information stored in image memory 1 and image output information for even frames 1o ・ ・ 2 ・ ・ 2 e ・ ・ 20 ・ ・ 3 ・ ・ 4 ・ ・ ・ 4a ・・ 4 b ・ ・ 4a υ 0 5 ・ ・ ・ 5e ・ ・ 50 ・ ・ 5m ・ 31 ・ ・ ・ ・Stored image information in image memory 1 and image output information for odd frames ・Stored image in image memory image memory 2 Information and image output information for even frames ・Stored image information in image memory 2 and image output information for odd frames Switching circuit Display control 1 circuit Memory address frame signal...Lowest signal of vertical address Image generation circuit Displayed for even frames Images displayed on the device 4 Images displayed on the display device 4 during odd frames - Composite image perceived by humans due to the afterimage effect of the human eye - Image memory 31a ・ 31b ・ 32 ・ ・ 33 ・ 34 ・ 35 ・・ 36 ・ ・ 37 ・ 38 ・ 39 ・ 40 ・ 41 ・ ・ Divided image memory ・ Divided image memo IJ ・ Brightness conversion table ・ D/A converter ・ Display device ・ Image memory ・ Image Memory, brightness conversion table, brightness conversion table, brightness adder, D/A converter, display device manufacturer Seiko Electronics Industries, Ltd.

Claims (1)

[Claims] an image storage means for storing at least two screens of images; a display control means for extracting image data from the image storage means and displaying it on a display device; a raster type display device; and a raster type display device, and generating and storing images in the image storage means. an image generating means; and a switching means for alternately outputting the image data of the image storage means by a signal synchronized with the frame and raster of the display screen of the display device generated by the display control means; An image display device characterized by displaying a composite video of images.