JPH0358690A - Television signal converter - Google Patents

Abstract

PURPOSE:To display a video signal while varying the lightness or lightness and color of a blanking part in matching with a luminance level of the video signal by providing a level processing circuit and a counter circuit. CONSTITUTION:The converter is provided with a level processing circuit 7 detecting a luminance level of a video signal, a blanking addition circuit 5 generating a blanking signal and adding it to a current standard television signal outputted from a signal processing circuit 3 and a counter circuit 8. Then the blanking addition circuit 5 is controlled in response to the luminance of the screen by the level processing circuit 7 and the counter circuit 8. Thus, the color and lightness of the blanking part are varied optionally and automatically. Moreover, when an output of the blanking addition circuit 5 is applied only to a luminance signal line, only the lightness is changed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is applicable to converting a high-definition television signal into a current standard television signal with a different aspect ratio. The present invention relates to a television signal conversion device having a function of automatically changing the brightness and color according to the brightness of a video signal and displaying the image.

BACKGROUND OF THE INVENTION In recent years, television signals such as high-definition television, which have transmission methods different from conventional television signals, have been developed and come into use. Along with this, the current standard 1 high-definition television signal will also be converted to a television signal,
It has become necessary to play back to conventional television receivers.

FIG. 3 shows a schematic diagram of a conventional television signal converter. In the figure, 1 is an A/D converter that converts the analog video detection signal from the tuner's detection circuit (not shown) into a digital signal, 2 is the RAM that stores the video signal, 3 is the number of scanning lines, 4 is a signal processing circuit that converts the aspect ratio; 4 is a synchronization processing circuit that detects the synchronization of the video detection signal and generates the synchronization of the standard television signal; 5 is a blanking circuit that displays the blanking portion during a period of no video signal; 6 A 1 Addition circuit, 6 Pa Signal processing circuit 3
D converts the processed digital signal into an analog signal
/A concert. Note that A is an input terminal for high-quality television signals, and B is an output terminal for standard television signals.

The operation of the television signal converter configured as shown below will be explained below.

A high-definition television signal {K} from a tuner and a detection circuit is converted into a digital signal by an A/D converter 1, and the aspect ratio and number of scanning lines are converted by a signal processing circuit 3. At this time, the RAM 2 stores video signals to be displayed on the screen. Furthermore, the synchronization processing circuit 3 detects synchronization of high-definition television signals and generates synchronization of standard television signals. An arbitrary blanking signal generated by a blanking addition circuit 5 is added to the digital signal output from the signal processing circuit 3, and the blanking signal is added to the digital signal output from the signal processing circuit 3.
The signal is then converted to an analog signal and displayed on a television receiver.

Problems to be Solved by the Invention However, as can be seen from the operation of the conventional example, when converting a high-definition television signal with a different aspect ratio from the current standard television signal to the current standard television signal, the aspect ratio is different. Therefore, it is necessary to add blanking areas unrelated to the video signal at the top and bottom of the screen, but at this time, if the blanking areas are fixed to black, it may cause burn-in on a part of the CRT. , which is undesirable because the screen becomes uneven when viewing standard television signals. Also, if the blanking part is displayed in a constant color other than black and brightness, the contrast of the screen will change to 1.
There was a problem in that it appeared to be lower or higher.

FIG. 4 is a characteristic diagram showing the problem. Here, A indicates the effective display range of the current standard television signal, B indicates the effective display range of the high-definition television signal, and C indicates the blanking portion.

Therefore, the present invention is based on such an intermediate point, eliminates the drawback, and provides a simple method for changing at least the brightness of the blanking portion depending on the brightness of the video signal of a high-definition television signal. The present invention provides a television signal conversion device that can perform the following functions.

Means for Solving the Problems The television signal conversion device of the present invention includes an A/D converter, a signal processing circuit, a synchronization processing circuit, a level processing path for detecting the luminance level of a video signal, and a blanking signal. A blanking addition circuit is provided to add to the current standard television signal output from the level signal processing circuit, and the detection output of the level processing circuit is added to the blanking addition circuit to perform blanking according to the brightness of the screen. At least the brightness of the ranking part is changed.

According to the television signal conversion device of the present invention, the brightness of the blanking portion of the video is adjusted according to the brightness of the screen by being equipped with a level processing circuit that detects the brightness of the video signal portion of the high-quality television signal. What's more, you can change the color.

Example Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 is a schematic block diagram showing one embodiment of the present invention.

In this figure, parts common to those in FIG. 3 are denoted by the same reference numerals, and detailed explanations will be omitted. 7 is a level processing circuit that detects the level of the luminance signal and controls the blanking addition circuit 5; 8 is a count circuit that counts the number of horizontal synchronizations and vertical synchronizations and outputs it to the level processing circuit 7;

Next, the operation will be explained using the tying diagram shown in FIG. In the same figure, (a) shows the luminance signal output from the signal processing circuit 3 of FIG. 1, (b) shows the horizontal synchronization signal output from the synchronization processing circuit 4, and (d) shows the synchronization This is a vertical synchronization signal output from the processing circuit 4. The counter circuit 8 counts the number of IHs based on the horizontal synchronization signal b, and the level processing circuit 7 calculates the brightness level of each IH.
Detect as shown in (C). The counter circuit 8 is reset by the vertical synchronizing signal d, and the luminance level of the next field is detected in the same manner.

(e) shows the effective period for each field of the counter circuit 8, during which the average value 5 of the luminance level is detected in the level processing circuit 7, and an arbitrary control signal is output based on the data. , the blanking addition circuit 5 allows the data of the blanking portions of the Y signal, RY signal, and BY signal to be arbitrarily varied.

In this way, by the level processing circuit 7 and the counter circuit 8,
By controlling the blanking addition circuit 6 according to the brightness of the screen, the color and brightness of the blanking portion can be changed arbitrarily and automatically. Note that by applying the output of the blanking addition circuit 5 only to the luminance signal line, the brightness can be changed.

As described above, according to the present invention, although the structure is simple and only requires the insertion of a level processing circuit and a counter circuit,
It is possible to provide a television signal conversion device that can display images by changing the brightness of the blanking part or the brightness and color according to the brightness level of the video signal, and has outstanding practical effects. It can be called an invention.

[Brief explanation of drawings]

FIG. 1 is a schematic block diagram of a television signal converter according to an embodiment of the present invention, FIG. 2 is a diagram showing the operation of an embodiment of the present invention, and FIG. 3 is a diagram of a conventional television. FIGS. 4a and 4b are characteristic diagrams illustrating conventional problems. 5...Blanking addition circuit, 7...
Level processing circuit, 8... Counter circuit

Claims (2)

[Claims] (1) a signal processing circuit that receives a high-definition television signal and converts it into a current standard television signal with a different aspect ratio, and a level processing circuit that detects the brightness of a video signal included in the high-definition television signal; and a blanking circuit for adding a blanking signal to the current standard television signal output from the signal processing circuit, and the detection output signal of the level processing circuit is added to the blanking circuit according to the brightness of the screen. A television signal converter configured to control at least the brightness of a blanking portion. (2) The television signal conversion device according to claim 1, wherein the blanking portion is configured to change color as well as brightness.