KR19980053584A - How to determine the video mode - Google Patents

Abstract

The present invention relates to a method for preventing a malfunction due to horizontal frequency discrimination in a mode determining apparatus for determining an input video signal. To this end, the present invention provides a control unit which detects a horizontal synchronization signal inserted into an image signal and provides the same to a controller. A first step of measuring a time for inputting a horizontal synchronization signal to the controller, a third step of calculating a frequency based on a provided horizontal synchronization signal and a measured time period, storing the calculated frequency in a memory, and increasing a counter The fourth step, the fifth step of repeating the first and second, third and fourth steps until the value of the counter becomes 2, whether the first and second horizontal frequencies calculated by the repeating operation match If the first and second horizontal frequencies do not match in the sixth and sixth steps of comparing, the first and second horizontal frequencies stored in the memory are erased and An eighth step of determining a mode according to a preset horizontal frequency of each mode when the first and second horizontal frequencies coincide in the seventh step and the sixth step of performing the operation again; switching to an image signal according to the determined mode It includes a ninth step to perform.

Description

How to determine the video mode

The present invention relates to video signal discrimination, and more particularly, to a method suitable for determining a mode of a video signal by using a horizontal synchronization signal inserted in an input video signal.

As is well known, a mode determination device for determining a mode of an input video signal in a monitor capable of processing a video signal of a conventional multi-mode inputs after setting and storing a horizontal frequency for each mode in a predetermined range. The horizontal frequency of the signal is operated in the mode of the corresponding range.

For example, an HDTV (high definition television, hereinafter abbreviated as HDTV) has a horizontal frequency of 33.75 kHz. If the horizontal frequency of an input signal is detected as 32.25 kHz within a period in which the horizontal frequency is set to 32 kHz to 35 kHz, The correction is performed by switching.

In the conventional multi-sync monitor having such a mode discrimination method, when the initial horizontal sync signal is inputted in a flexible manner without a constant input, it does not recognize the horizontal frequency and malfunctions, and a high voltage is generated due to the frequency difference. There was a problem that a breakdown of the horizontal output transistor occurred.

Accordingly, an object of the present invention is to solve the above-described problems of the prior art, and to provide an image mode discrimination method which repeatedly detects a horizontal synchronizing signal and operates at a frequency of a predetermined mode.

In order to achieve the above object, the present invention provides a first step of detecting and providing a horizontal synchronization signal inserted into a video signal to the control unit, a second step of measuring the time the horizontal synchronization signal is input to the control unit and providing it to the control unit, A third step of calculating a frequency based on a horizontal synchronizing signal and a measured time period, a fourth step of storing the calculated frequency in a memory, incrementing a counter, first, second, and second until the value of the counter becomes two; 3, the fifth step of repeating the fourth step, the sixth step of comparing whether the first and second horizontal frequencies calculated by the repetition performed match, the first and second horizontal frequency do not match in the sixth step If not, the first and second horizontal frequencies stored in the memory are erased and the operation from the first step is performed again in the seventh and sixth steps. An image mode discrimination method includes an eighth step of determining a mode according to a determined horizontal frequency of each mode, and a ninth step of switching a video signal according to the determined mode.

1 is a block diagram for determining an image mode according to a preferred embodiment of the present invention.

2 is a flowchart illustrating an image mode determination process according to an exemplary embodiment of the present invention.

<Description of the code | symbol about the principal part of drawing>

10: image signal detection unit 20: control unit

30: counter 40: timer

50: memory 60: comparison unit

70 mode determining unit 80 switching unit

The above and 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, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram for determining a video mode according to an exemplary embodiment of the present invention, wherein the video signal detector 10, the controller 20, the counter 30, the timer 40, the memory 50, and the comparator are shown. 60, a mode determination unit 70, and a switching unit 80.

The image signal detecting unit 10 detects only the horizontal synchronizing signal from the received image signal and provides it to the control unit 20. The counter 30 allows the counter to count up when the horizontal frequency calculated by the control unit 20 is input to the memory. The timer 40 measures the time at which the horizontal synchronization signal is generated in the control unit 20 and also provides the control unit 20 to the control unit 20.

On the other hand, the control unit 20 receives the horizontal synchronization signal provided from the image signal detection unit 10 and receives the time measured from the timer 40 and calculates the frequency based on this, the value of the counter 30 is 2 Ie calculate the horizontal frequency twice and store it in the memory 50 until it is repeated.

The comparator 60 compares the two horizontal frequencies calculated by the controller 20, that is, the first and second horizontal frequencies, and provides the comparison signal to the mode determiner 70. The control unit 80 is controlled by transmitting a mode control signal according to the horizontal frequency of each mode to the switching unit 80.

Meanwhile, FIG. 2 is a flowchart illustrating an image mode determination method according to an exemplary embodiment of the present invention with reference to FIGS. 1 and 2.

When the video signal is received from the signal receiver, not shown, and provided to the video signal detector 10, the video signal detector 10 detects the horizontal sync signal and provides the detected horizontal sync signal to the controller 20 (step 11). When the horizontal synchronizing signal is input, the control unit 20 operates the timer 40 to measure the time when the horizontal synchronizing signal is input (step 12).

Then, the control unit 20 calculates the frequency of the horizontal synchronization signal input by using the time measured by the timer 40 as a cycle (step 13), stores it in the memory 50 (step 14), and then the counter 30 The control signal is generated to perform up counting (step 15), and the above-described process is repeated until the value of the counter 30 becomes 2 (step 16).

Meanwhile, when the value of the counter 30 is 2, the controller 20 generates a control signal to the memory 50 and provides the comparator 60 with the two horizontal frequencies stored, that is, the first horizontal frequency and the second horizontal frequency. The comparator 60 compares the first and second horizontal frequencies (step 17). At this time, if the first and second horizontal frequencies do not coincide with each other, the controller 20 is stored in the memory 50. The value is erased (step 18), and the horizontal signal is received from the image signal detector 10 again (step 11). If the first and second horizontal frequencies coincide in the above-described step (step 17), the comparator 60 generates a comparison signal and provides it to the mode determiner 70. The mode of the input image signal is determined based on the set horizontal frequency of each mode and the comparison signal of the comparison unit 60 (step 19) to control the switching unit 80. The switching unit 80 controls the mode determination unit. The video signal is switched according to the mode control signal determined at 70 (step 20).

For example, when the first and second horizontal frequencies calculated by the controller 20 coincide with 33.776 kHz, the mode determination unit 70 determines that the switching unit 80 is 33.75 based on a preset horizontal frequency of 33.75 kHz. Control to operate with.

Therefore, as described above, the horizontal frequency of the image signal may be repeatedly detected and switched to the preset horizontal frequency mode.

As described above, according to the present invention, the horizontal frequency of the input video signal is repeatedly detected twice to increase the stability of the horizontal frequency measurement, thereby preventing the damage of the horizontal drive due to the malfunction of the system and providing a stable screen. In addition, when the horizontal synchronization signal is unstable, the video signal can be muted to protect the system.

Claims (1)

In the mode discrimination method of a multi-synchronous monitor that accommodates a video signal of various synchronization, A first step of detecting a horizontal synchronizing signal inserted into the video signal and providing the same to a control unit; A second step of measuring a time for inputting a horizontal synchronization signal to the controller; A third step of calculating a frequency based on the provided horizontal synchronizing signal and the measured time period; A fourth step of storing the calculated frequency in a memory and incrementing a counter; A fifth step of repeatedly performing the first, second, third and fourth steps until the value of the counter becomes two; A sixth step of comparing whether the first and second horizontal frequencies calculated by the repetition are matched; A seventh step of canceling the first and second horizontal frequencies stored in the memory and repeating the operation after the first step when the first and second horizontal frequencies do not match in the sixth step; An eighth step of determining a mode according to a preset horizontal frequency of each mode when the first and second horizontal frequencies coincide in the sixth step; And a ninth step of performing switching on the video signal according to the determined mode.