KR0159372B1 - Method for automatically switching the broadcast signal mode in a video cassette recorder - Google Patents

Abstract

The present invention relates to a method of switching a video cassette recorder, and more particularly, to automatically switch the color mode when the set color system (Color System) is different from the color system of an input signal or a reproduction signal. It is about automatic switching method of V-seal.

To this end, the present invention provides a method of automatic switching of V-CAL to switch the color mode using a vertical synchronization signal and a changing color killer voltage, the method comprising: determining whether a play key signal is input (200); If the playkey signal is input, set to the NTSC mode (201), and determining whether a vertical synchronization signal for the PAL-N method is input (202); Setting the PAL-N method to the PAL-N method if the vertical synchronization signal is input (203); If the vertical synchronization signal of the PAL-N method is not input, determining whether a low-level killer signal is input (204); If the low-level killer signal is input, setting the NTSC method (205); Determining whether a high-level killer signal is input if the low-level killer signal is not input (206); Setting a forced mode when a high-level killer signal is input (207); If the high-level killer signal is not input, it is configured to include the step 208 of setting the PAL-M method, and there is an advantage that there is no need to add a separate circuit by automatically switching the color mode in software. .

Description

Automatic Switching Method of Video Cassette Recorder

1 is a switching circuit diagram of a typical video cassette recorder.

2 is a flowchart for performing automatic switching of a video cassette recorder according to the present invention.

* Explanation of symbols for main parts of the drawings

10 comparison unit 11 switching unit

12: D flip-flop Q1, Q2: switching transistor

The present invention relates to a method of switching a video cassette recorder (hereinafter referred to as Bricial), and more particularly, when the set color system (Color System) is different from the color system of the input signal or the reproduction signal automatically; The automatic switching method of V-Cal for switching the color system mode.

In general, the color schemes used are transmitted according to some standard schemes adopted by various regions or countries. For example, North America, Latin America, South Korea, Japan, and Southeast Asia adopt the NTSC (National Television System Committee), while Europe and China, such as the United Kingdom, Germany, Italy, and Switzerland, use the PAL (Phase Alternation Line) method in France. The SECAM (Sequentiel Couleur A Memorie) method is adopted.

FIG. 1 is a circuit diagram of a general color switching device, and includes a comparator 10, a switching unit 11, a D flip-flop 12, and switching transistors Q1 and Q2.

In the present specification, first, the color scheme is NTSC high level, PAL is low level, and the color scheme of the input signal is different from the currently set color scheme. Let's look at the case where the signal from is received or played back from the videotape.

In this case, a voltage of a killer mode (for example, 3.1V in the present specification) is input to the non-inverting terminal (+) of the comparator 10, and a reference voltage (for example, the present specification) is input to the inverting terminal (-). 2 ~ 2.5V) is configured to be input.

That is, as described above, when the color scheme of the input signal is different from the currently set color scheme, the input voltage of the non-inverting terminal (+) is input to a voltage larger than the reference voltage of the inverting terminal (-). 10) outputs a high level logic signal.

Accordingly, the switching unit 11 is turned on, and the switching pulse is input to the clock pulse CP of the D flip-flop 12 to change the state of the output Q. That is, the output Q is output from the high level logic signal to the low level logic signal so that the switching transistor Q1 is turned off and the switching transistor Q2 is turned on to switch the color mode.

In this case, since the color scheme is switched by the changed voltage as described above, that is, the color scheme of the input signal becomes the same as the currently set color scheme, so that the color of the non-inverting terminal (+) of the comparator 10 is colored. ) Voltage (for example, 1.9V in the present specification) is input, and a low level logic signal is output to the output of the comparator 10.

Accordingly, since the switching unit 11 is turned off and no switching pulse is input to the clock pulse CP of the D flip-flop 12, the output Q maintains the changed state as it is.

On the other hand, when the color system reproduced from the receiving or videotape is the same as the currently set color system (in this specification, the NTSC system signal is reproduced from the receiving or videotape with VLC or TV set to the NTSC system). Looking at it as follows.

Color mode voltage (for example, 1.9V in the present specification) is input to the non-inverting terminal (+) of the comparator 10, and a reference voltage (for example, 2 in the present specification) is input to the inverting terminal (-). ~ 2.5V) is configured to be input.

At this time, since the input voltage of the non-inverting terminal (+) is smaller than the reference voltage of the inverting terminal (−), the comparator 10 outputs a low level logic signal.

Therefore, since the switching unit 11 is turned off, the switching pulse is not input to the clock pulse CP of the D flip-flop 12, so that the output Q of the D flip-flop 12 maintains the current state.

However, as described above, many elements are used to construct a circuit of an automatic switching device of V-Cal, which causes a problem in that the cost is increased.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and an object of the present invention is to provide a vertical synchronization signal and a changing color killer voltage level when a color scheme inputted to a BC is different from a currently set color scheme. It is to provide an automatic switching method of V-CAL to reduce the cost by automatically switching the color scheme to software using the software.

A feature of the present invention for achieving the above object is a method of automatic switching of V-Cal to switch the color mode using the vertical synchronization signal and the changing color killer voltage, the process comprising: determining whether a play key signal is input; Setting the NTSC mode when the playkey signal is input, and determining whether a vertical synchronization signal for the PAL-N method is input; Setting a PAL-N method when a vertical synchronization signal of the PAL-N method is input; Determining whether a low-level killer signal is input if the PAL-N type vertical synchronization signal is not input; Setting the NTSC method when a low-level killer signal is input; Determining whether a high level killer signal is input when the low level killer signal is not input; Setting a forced mode when a killer signal having a high level is input; If the high-level killer signal is not input, it is configured to include a process of setting the PAL-M method.

Other objects and various advantages of the present invention will become more apparent from the preferred embodiments of the present invention described below with reference to the accompanying drawings by those skilled in the art.

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

Table 1 is a truth table for performing automatic switching of V-Cal according to the present invention.

At this time, k1, k2 are control signals outputted to the video IC terminal to set the color mode in accordance with the vertical synchronization signal and the killer output signal to which the microcomputer (not shown) is input.

That is, as shown in Table 1, when k1 and k2 are both 0, the control signal is set to the NTSC method, kl is 0, and when k2 is 1, the control signal is set to the PAL-M method, and k1 is 1, k2 is a control signal that is set to NTSC or PAL-M when the signal played back from the videotape is a black and white signal when 0, and a control signal that is set to PAL-N when both k1 and k2 are 1 Indicates.

FIG. 2 is a flowchart for performing an automatic switching method of a VR in accordance with the present invention, and automatically switches a color mode of a VC using a vertical synchronization signal and a killer output signal for each color scheme.

First, the microcomputer (not shown) determines whether a playkey signal is input in step 200. As a result of the determination, if the Playkey signal is input, the process proceeds to step 201, the color system is set to the NTSC method, and the process proceeds to step 202.

The microcomputer (not shown), which proceeds to step 202, detects the input vertical synchronization signal and determines whether the vertical synchronization signal for the PAL-N method is input.

At this time, the vertical synchronization signal of the PAL-N method is 50Hz, NTSC and PAL-M method is 59.94Hz.

As a result of the determination, if the input vertical synchronization signal is a PAL-N type vertical synchronization signal, that is, 50 Hz, the flow proceeds to step 203 to set the PAL-N method.

If the vertical synchronization signal input in step 202 is not a PAL-N type vertical synchronization signal, the microcomputer proceeds to step 204 to determine whether the killer output signal is a low level logic signal.

As a result of the determination, if the low level logic signal between the killer output signals proceeds to step 205 to set to the NTSC method.

In addition, if the killer output signal is not a low level logic signal in step 204, the microcomputer proceeds to step 206 to determine whether the killer output signal is a high level logic signal.

As a result of the determination, if a high-level killer signal is input, the process proceeds to step 207 to set to a forced mode set to NTSC or PAL-M. If the killer signal of the high level is not input, the process proceeds to step 208 to set the PAL-M method.

As described above, the method of the present invention has the advantage that it is not necessary to add a separate circuit by automatically switching the color scheme in software according to the vertical synchronization signal and the killer output signal.

While the invention has been shown and described with respect to certain preferred embodiments, those skilled in the art will recognize that various modifications and changes can occur without departing from the spirit and scope of the invention as set forth in the claims below.

Claims (1)

An automatic switching method of V-CAL for switching the color mode using a vertical synchronization signal and a changing color killer voltage, the method comprising: determining whether a play key signal is input (200); If the playkey signal is input, set to NTSC mode (201) and determine whether a vertical synchronization signal for the PAL-N method is input (202); Setting (203) a PAL-N method when the vertical synchronization signal of the PAL-N method is input; If the vertical synchronization signal of the PAL-N method is not input, determining whether a low-level killer signal is input (204); Setting (205) the NTSC method when the low-level killer signal is input; Determining whether a high level killer signal is input if the low level killer signal is not input (206); Setting a forced mode when the high-level killer signal is input (207); And setting (208) the PAL-M method if the high level killer signal is not input.