JPH01143580A - Teletext receiver - Google Patents

Abstract

PURPOSE:To attain the display of a superimposing pattern with an optional size by reading a data stored in a memory and estimating the superimposed area of a text picture depending on said data. CONSTITUTION:At first a video input A is given to a synchronizing separator circuit 4 to generate a horizontal synchronizing signal H and a vertical synchronizing signal V and gives them to a display control circuit 10. Furthermore, the signal H is given to a clock generating circuit 1 to generate a clock signal synchronously with the signal H, which is given to the circuit 10. The circuit 10 frequency-divides the clock signal to generate a 6-bit horizontal address signal synchronously with the signal 11. As a vertical address signal, the signal H is subject to frequency division and the 6-bit address signal is generated synchronously with the signal V. Then the memory 12 is accessed by the address in 6-bit both horizontal and vertical directions, then the data is read and the display position on the screen is controlled in the minimum display unit of mini-block.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a teletext receiving apparatus that performs superimposed display.

Conventional technology In recent years, teletext has been put into practical use and is becoming widespread in every household.

The superimposed display is convenient because it allows you to view text information while viewing the image on the television receiver. For superimposed display of teletext broadcasts, in addition to the display determined by the protocol, a method of forcibly superimposing on the receiver is also used. Some methods are still being used to reduce the horizontal and vertical display area of text information and superimpose it so that it does not interfere with the display of the main television image.

Hereinafter, a conventional teletext receiver as described above will be explained with reference to the drawings.

FIG. 5 shows a block diagram of a superimposing section of a conventional teletext receiver. In FIG. 5, a clock generation circuit 1 generates a clock of 5.72 MHz, which is about 364 times the frequency of the horizontal synchronization signal, in synchronization with the horizontal synchronization signal synchronously separated by the synchronization separation circuit 4. Reference numeral 2 denotes a display timing generation circuit which inputs the clock generated by the clock generation circuit 1 and generates a display signal synchronized with the horizontal synchronization signal and the vertical synchronization signal. When viewed on a television screen, this display signal is a signal that forms an area surrounded by a frame as shown in FIG. 3 (E) on the screen displaying the television image. The output of the display timing generation circuit 2 is added to the switching circuit 3, and from this switching circuit 3 RG
The video signal inputted at B (a) and the character image signal of character information synchronized with the video signal (b) are switched and outputted as superimposed output (c) in RGB. If these signals are viewed on a television screen, it will look like the one shown in FIG. 3, and the character image information will appear to be superimposed on the television image. Furthermore, in the text image information portion of FIG. 3(e), the effect of information transmission will be further enhanced if the text information, which conventionally should be displayed using the entire surface of the television screen, is reduced and displayed.

Problems to be Solved by the Invention However, in the above configuration, when superimposing, the position and size of character information to be displayed are
There is a drawback that the timing is fixed by a signal specifying the timing output from the display timing generation circuit 2 shown in the figure.

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide a teletext receiver in which the display position and size of character images can be freely set during superimposed display.

Means for Solving the Problems To achieve this object, the teletext receiving device of the present invention comprises a clock generation circuit, a display control circuit, a memory, a synchronization separation circuit, and a switching circuit. The display area to be superimposed on the screen can be variably set using synchronized display address signals and display timing signals.

Operation With the above configuration, when you want to display a superimposed display at any position on the TV screen, by writing data to the memory in the corresponding area, the display control circuit reproduces the signal in synchronization with the TV screen and sends it to the switching circuit. In addition, it is possible to switch between video input and character image input for superimposed display.

Embodiment Hereinafter, a teletext receiver according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a teletext receiver according to an embodiment of the present invention. Components similar to the conventional configuration shown in FIG. 6 are given the same reference numerals, and detailed explanation thereof will be omitted.

In FIG. 1, 1 is a clock generation circuit, 3 is a switching circuit, 4 is a synchronization separation circuit, (a is a video input, middle) is a character image input, and the above configuration is the same as that in FIG. 3. Reference numeral 1o denotes a display control circuit which receives as input the horizontal synchronizing signal and vertical synchronizing signal synchronously separated by the synchronous separating circuit 4, and the clock generated by the clock generating circuit 1. 11 is a control circuit that uses an arithmetic processing unit (hereinafter abbreviated as CPU). 12 is a readable/writable memory that uses a random access memory (hereinafter abbreviated as RAM).

The operation of the teletext receiving apparatus configured as described above will be described below. First, the video input mark is input to the synchronization separation circuit 4, and the horizontal synchronization signal H9 and the vertical synchronization signal V
is created and added to the display control circuit 10. Furthermore, the horizontal synchronization signal H is added to the clock generation circuit 1, and the horizontal synchronization signal H
A clock signal of approximately 5.73 MHz synchronized with is generated using a gated oscillator method and applied to the display control circuit 1o. The display control circuit '10 divides the clock signal and generates a 6-bit horizontal address signal synchronized with the horizontal synchronization signal. Further, as for the vertical address signal, a 6-bit address signal is generated by frequency-dividing the horizontal synchronizing signal H and synchronizing with the vertical synchronizing signal V. This address signal will be further explained using FIG. 2. In this embodiment, one miniblock is 4 bits in the horizontal direction and 4 horizontal scanning periods in the vertical direction, which is the minimum unit of display.

On a teletext screen, 248 dots are displayed horizontally and 204 lines are displayed vertically, so the total number of dots is 3162.
It can be divided into mini-blocks. Therefore, if one miniblock is assigned to one bit of memory, 3162 bits of memory can correspond to that address specification. Therefore, if the memory 12 is accessed and read using an address of 6 bits in the horizontal direction and 6 bits in the vertical direction, the minimum display unit will be the second
The display position on the screen is controlled in units of mini-blocks in the diagram. The control circuit 11 addresses the memory 12 and writes "o".
” or “1” signals. During periods other than when the display control circuit 10 is accessing the memory 12, the control circuit 11 accesses the memory 12 and records signals. As the period, a period corresponding to a screen area other than the character image display screen shown in FIG. 4 is used.

The output of the memory 12 is converted into a signal (
display address signal 1 display timing signal) switching circuit 3
In addition, as shown in FIG. 3, a character image is displayed in the part (e), and a television image is displayed in the other parts. Furthermore, if the contents of the memory 12 are updated, as shown in FIG. Target 43.3.1111 can be seen over a vertical period of 12.95 m5, and the third
It can also be reduced to any size as shown in the figure. Usually Figure 1 (
When creating the character stroke shown in b), the above-mentioned memory, etc. is used, and the elements constituting colors such as R, G, and B are colored units of 4 dots in the horizontal direction and 4 lines in the vertical direction, and the circuit Sharing can be achieved and costs can be reduced. In this embodiment, the horizontal and vertical lines are each 4 dots x 4 lines, but the horizontal.

1 dot x 1 line in each vertical direction can be easily achieved.

As described above, according to this embodiment, the signal recorded in the memory 12 is used as the switching signal between the television image and the character image, and by specifying the display area of the character image, a character image of any size can be created. Can be superimposed.

Effects of the Invention As described above, according to the present invention, the data recorded in the memory is read out, and the suit of character images is created using this data.
By estimating the localization area, a superimposed screen of any size can be displayed, which has great practical effects.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a teletext receiver according to an embodiment of the present invention, FIG. 2 is a front view illustrating a display unit of the present invention, and FIGS. 3 and 4 are display examples of the present invention. The front view shown in FIG. 6 is a block diagram showing a conventional example. 1... Clock generation circuit, 3... Switching circuit, 4... Synchronization separation circuit, 1o...
Display control circuit, 11... Control circuit, 12...
···memory. Name of agent: Patent attorney Toshio Nakao and 1 other person
2 Illustration 3 Figure 4

Claims (1)

[Claims] a synchronization separation circuit that creates a synchronization signal from an input television video signal; a clock generation circuit that generates a clock signal of n times the frequency synchronized with the synchronization signal; and a display address signal synchronized with the synchronization signal using the clock signal as input. and a display control circuit that generates a display timing signal, a memory, a control circuit that controls the memory, and a switching circuit, and a display that generates data recorded in the memory from the control circuit in the display control circuit. A video signal that is an input of the switching circuit and a character image signal synchronized with this video signal are read out in synchronization with the address signal and the display timing signal and added to the switching control terminal of the switching circuit. What is claimed is: 1. A teletext receiving device characterized in that the teletext receiving device is characterized in that the display is switched by a signal and the position of superimposition is varied according to the area recorded in the memory.