KR0160612B1 - Apparatus for discriminating image signals - Google Patents

Abstract

The present invention provides a signal input determination device for determining whether an image signal is input or not, and in particular, having an internal synchronization signal generator to stably determine whether or not a signal is input without being influenced by an external synchronization signal. A synchronization signal separating means (10) for separating a first synchronization signal from an external image input signal; Toggle means for changing the logic state in response to the input of the separated synchronization signal; Synchronization generating means for generating an internal second synchronization signal; Shifting means for shifting the second synchronization signal output from the synchronization generating means by a predetermined value each time an output from the toggle means is input; Toggle checking means for checking whether the state is repeated for a predetermined value by receiving the output shifted from the shifting means as an input signal so as to output a video signal input determination signal; And mode output means for outputting a second synchronous signal from the synchronization generating means in accordance with the source presence determination signal from the toggle checking means.

Description

Video signal presence and absence device

1 is a block diagram of a video signal discrimination apparatus according to the present invention.

2 is a waveform diagram when a video signal is input.

3 is a waveform diagram when no video signal is input.

4 is a view showing one example of a toggle means and a shifting means in the present invention.

5 is a view showing an example of a toggle check means applicable in the present invention.

* Explanation of symbols for main parts of the drawings

10: synchronization signal separation means 20: toggle means

30: shifting means 40: synchronization signal generator

50: toggle check means 60: mode output means

The present invention provides a signal input determination device for determining whether an image signal is input or not, and in particular, having an internal synchronization signal generator to stably determine whether or not a signal is input without being influenced by an external synchronization signal. It is about.

In the related art, a compound synchronization is generated internally in hardware when a source signal is not input from a video tape recorder (VTR) laser disk player (LDP), or when a tape or a laser disk is stopped. It has a color generator circuit inside the signal and sends a blue signal to the screen for display on the monitor. In addition, when an image signal is input, a determination is made as to whether a signal is input in the process of interfacing with the microcomputer to determine whether the signal is input. In this process, when the synchronization between the hardware and the microcomputer is not precise, there may be a momentary flicker, and the reliability may be deteriorated depending on the state of the input signal when the input video signal is interfaced with the microcomputer. In addition, there is a problem in that a multi-panel without a microcomputer and an interface is provided with a device capable of separately determining whether a signal is input or not, and the mode must be independently determined.

Accordingly, it is an object of the present invention to provide an apparatus for determining the presence or absence of an image signal that can stably determine whether an image signal is input.

In order to achieve the above object, the present invention provides a synchronization separation means for separating the first synchronization signal from the external image input signal; Toggle means for changing the logic state in response to the input of the separated synchronization signal; Synchronization generating means for generating an internal second synchronization signal; Shifting means for shifting the second synchronization signal output from the synchronization generating means by a predetermined value each time an output from the toggle means is input; Toggle checking means for checking whether the state is repeated for a predetermined value by receiving the output shifted from the shifting means as an input signal so as to output a video signal input determination signal; And a mode output means for outputting a second synchronization signal from the synchronization generating means in accordance with the source presence / absence determination signal from the toggle check means.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic block diagram of a video signal discrimination apparatus according to the present invention.

1 shows a synchronization signal separator 10 for detecting a vertical synchronization signal from a received external image signal, a toggle means 20 for toggling a state according to an input signal, and a shifting means 30 for shifting an input signal. ), A synchronization signal generator 40 that is built in the video device to generate a vertical synchronization signal, a toggle check means 50 for checking the state change of the signal, and outputs a video signal input or not discrimination signal according to the input mode signal The mode output means 60 is comprised.

The operation of each component of FIG. 1 is as follows. When the video signal is input from the outside, the synchronizing signal separating means 10 separates the vertical synchronizing signal VSYNC1 from the image signal and inputs the separated vertical synchronizing signal VSYNC1 to the toggle means 20. The toggle means 20 serves to toggle the current state whenever the vertical synchronization signal separated by the synchronization signal separation means 10 is applied. That is, when the output state of the existing toggle signal is a high state, if the vertical synchronization signal VSYNC1 detected from the synchronization signal separating means 10 is input, it serves to toggle the output state low. In addition, when the output state is low, when the vertical synchronizing signal VSYNC1 is input from the synchronizing signal separating means 10, the state of the currently output signal is toggled from low to high state. Therefore, when the state of the vertical synchronizing signal VSYNC1 from the synchronizing signal separating means 10 is continuously high or low, that is, when there is no input of an image signal from the outside, the output signal of the toggle means 20 changes in the state. There is no. The toggle means 20 inputs the signal which toggles the current state every time the activated signal from the synchronization signal separation means 10 is input to the shifting means 30.

In addition to the vertical synchronizing signal VSYNC1 detected by the synchronizing signal detecting means 10 by an image signal flowing from the outside, a synchronizing signal generator 40 for generating a stable synchronizing signal therein is provided inside the apparatus. The internal synchronization signal generator 40 installed as described above generates a stable synchronization signal and supplies the vertical synchronization signal VSYNC2 to the shifting means 30 and the mode output means 60.

In the shifting means 30 which inputs the output signal from the toggle means 20 and the stable synchronization signal output from the synchronization signal generator 40, when the state of the input signal from the toggle means 20 changes. Each time the output signal of the toggle means 20 is shifted by a certain integer multiple of the frequency of the vertical synchronization signal VSYNC2 input from the synchronization signal generator 40. At this time, the output signal of the toggle means 20 is preferably shifted three to five times, respectively.

The shifted output from the shifting means 30 is input to the toggle checking means 50, and the toggle checking means 50 checks whether the input signal is repeatedly high and low by a predetermined value. At this time, the allowance of the toggle check by a predetermined value is to prevent the check of the input vertical synchronization signal (VSYNC1) is shaken, and to improve the reliability. The check of this state is for determining whether the video signal is input. If there is no video signal input, since the vertical synchronizing signal VSYNC1 is continuously high or low, the toggle check means 50 keeps the high or low state. Since the signal is output and the high and low repetition is not performed, the stop and input signal no-mode signals indicating no stop and no input signal are output.

However, when there is a video signal input, the vertical synchronizing signal VSYNC1 is detected and the toggle checking means 50 repeats the high and low signals, so that the playback and input signals are being input. Generates a mode signal. The generated input signal presence / absence discrimination signal is input to the mode output means 60, and latched into a stable vertical synchronizing signal VSYNC2 generated by the synchronization signal generator 40 to finally output the mode discrimination signal.

The shifting means used in the present invention can be easily configured by using a shift register composed of a D flip flop shown in FIG. Also in the case of the toggle check means, the check of the state change of the shifted output signals from the shifting means to high or low can be easily configured using the NAND gate and the OR and AND gate shown in FIG. Can be.

Referring to FIG. 2 and FIG. 3, the waveform diagrams in the case of the presence or absence of signal input from each component of the video signal discrimination apparatus of the present invention will be described in detail as follows.

2 shows a waveform diagram of each component when there is an input of a video signal. When the video signal is input, the synchronizing signal separating means 10 separates and outputs the vertical synchronizing signal at a predetermined time interval from the original video signal. (Figure 2a). The separated vertical synchronous signal is input to the toggle means 20, and the toggle means outputs a toggle signal indicating a changed state each time the vertical synchronous signal is activated, and thus the vertical synchronous signal of FIG. 2a as shown in the waveform diagram of FIG. 2b. When to change from low to high toggles the state of the signal and outputs it to the shifting means (30).

The internal synchronous signal generator 40 generates a vertical synchronous signal VSYNC2 having the same pulse width as the synchronous signal detected from the image signal input from the outside, and outputs it to the shifting means 30 (Fig. 2C). ).

The shifting means 30 shifts the signal input from the toggle means 20 until the time point at which the vertical synchronization signal input from the synchronization signal generator 40 changes from low to high (FIG. 2D). Subsequently, the input signal from the toggle means is shifted several times and outputted (Figs. 2e, 2f and 2g). The shifted output signals are respectively input to the toggle check means 50 to check whether each shifted output is repeated low or high, and maintains the high signal if any one is repeated (2h). In the case of the mode output means 60, if the signal input from the toggle check means 50 is maintained as a high signal indicating that the video signal is input, the mode discrimination signal is latched as a stable vertical synchronization signal VSYNC1 to output the final output. send.

FIG. 3 is a waveform diagram of each component in the case where there is no input of the video signal (FIG. 3A). Since there is no change in the state of the signal, the synchronization signal separating means 10 keeps the high state (FIG. 3B). Degree). Accordingly, the shifting means 30 shifts and outputs only the signal having no change in the state in FIG. 3b at a predetermined interval (3d, 3e, 3f, and 3g), and the toggle checking means 50 Since there is no state change of the shifted signal, only the low state signal is output (Fig. 3h). Therefore, the mode output means 60 also outputs a low state signal indicating that no signal is input (FIG. 3i).

As described above, the present invention enables a multi-channel such as a discrimination signal or a closed circuit TV to internally output a synchronization signal (SYNC) or a blue signal when a stop mode and a video input signal are not input in a video tape recorder or a laser disk player. When no single source is input in the state, a constant clamp must be sent to the display of the channel, which can be used to detect traffic lights.

Claims (2)

Synchronization signal separation means for separating the first synchronization signal from the external image input signal; Toggle means for changing a logic state in response to the input of said first synchronization signal; Synchronizing signal generating means for generating a second synchronizing signal; Shifting means for shifting the output signal of the toggle means each time by an integer multiple of the frequency of the second synchronization signal output from the synchronization signal generation means each time the output from the toggle means is input; Toggle checking means for checking whether the logic state is repeated a predetermined number of times by receiving the shifted outputs from the shifting means as input signals to determine whether an image signal is input; And a mode output means for latching the second synchronization signal from the synchronization signal generating means and outputting a determination signal according to the presence / absence determination signal of the input signal from the toggle checking means. Device. 2. The apparatus as claimed in claim 1, wherein the toggle checking means has a repetition frequency of 3 to 5 times in a logic state.