KR100193616B1 - Video signal encryption device - Google Patents

Abstract

[purpose]

When the video signal is transmitted from a cable broadcasting station, the present invention devises a scheme different from the conventional video signal encryption scheme, and configures a circuit in a unique manner to change the luminance level of the video signal, and changes the level of the video signal multiplely. In addition, by changing the level of the video signal for each line selectively to realize the video signal encryption effect and low-cost high-definition.

[Configuration]

The present invention provides a stabilization circuit section for keeping the synchronization signal and the gain of an input video signal constant, a sample / hold section for making the DC stabilized output to be easily controlled at a later stage, and a compensation for signal loss. A first amplifier unit, a first mux unit for restoring an encrypted video signal to its original state and controlled by a reference signal applied by an offset control unit, a second amplifier unit amplifying using a reference signal applied by the offset control unit; A third amplifier unit for changing an offset, a second mux unit for inserting a reference signal at a predetermined position of the video signal under the control of the logic circuit unit, a fourth amplifier unit for outputting an encrypted video signal, and an amplifying five amplifier unit And a synchronous signal separator for separating the synchronous signal of the video signal, and changing the offset of the offset control unit of the reference signal under the control of the microcomputer. A first mux unit, a logic circuit unit for controlling the second mux unit, a screen unit for displaying the current control state by the control of the microcomputer, and a control unit for allowing the microcomputer to be operated by manual and remote control.

Description

Video signal encryption device

1 is a block diagram of a conventional video signal encryption device.

2 is a block diagram of a video signal encryption apparatus according to the present invention.

3A is a waveform diagram of an input video signal.

(b) is an output waveform diagram of a sample / hold part.

(c) is an output waveform diagram of a synchronization signal separator.

(d) is an output waveform diagram of the first mux.

(e) is an output waveform diagram of a second mux.

* Explanation of symbols for main parts of the drawings

1: Stabilization circuit part 2: Sample / hold part

3: first amplifier part 4: first mux part

5: 2nd amplifier part 6: 3rd amplifier part

7: second mux part 8: fourth amplifier part

9: offset control unit 10: logic circuit unit

11: micom 12: control unit

13: screen portion 14: fifth amplifier portion

15: Sync signal separator 16: Channel selector

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for encrypting a video signal, wherein a cable TV (CATV) transmitting station changes and transmits a luminance level of a video signal, thereby preventing non-subscribers from watching TV and preventing unauthorized eavesdropping. A video signal encryption apparatus is described.

In general, when it is necessary to encrypt pay-TV or other video signals so that they cannot be stolen on a general television, the asynchronous signals of the video signals are attenuated so that the TVs do not recognize the sync signals of the video signals, The video signal encryption device and the decryption device are used to change a signal such as to invert the signal to change the color and luminance, or to shift the sync signal to distort the image due to the inconsistency of the sync signal when receiving a television.

FIG. 1 is a block diagram of a conventional video signal encryption circuit. The modulator 100 converts an input video signal into a video and audio intermediate frequency, and attenuates a synchronization signal of a video intermediate frequency modulated by the modulator 100. The switching unit 101 and the logic circuit unit 104 which provides a switching timing pulse to the switching unit 101 under the control of the microcomputer 102 or the remote control unit 103.

The conventional video signal encryption apparatus configured as described above modulates the video signal input from the modulator 100 to the video and audio intermediate frequencies, and converts the horizontal synchronization signal of the modulated video intermediate frequency VIF into the switching unit 101 and the logic. The logic circuit unit 104 attenuates and encrypts the timing pulses provided by the circuit unit 104. The logic circuit unit 104 generates a timing pulse based on the synchronization signal of the image input signal and provides the timing pulse to the switching unit 101.

Further, the timing information of the attenuated section is AM-modulated to a carrier of the voice intermediate frequency (SIF) and transmitted at a high frequency.

However, the conventional video signal encryption apparatus uses a synchronization signal suppression method that simply attenuates the synchronization signal of the image intermediate frequency, but this technique has a problem that the restoration circuit is complicated and the image quality deteriorates during restoration.

Therefore, the present invention has been made to solve the various problems as described above. The main object of the invention is to devise a method different from the conventional video signal encryption method when transmitting a video signal from a cable broadcasting station, the lumi of the video signal By constructing a circuit in a unique manner to change the nonce level, the low cost and high image quality are achieved while having an encryption effect of the video signal.

Another object of the present invention is to change the level of the video signal to multiple, and to selectively change the level of the video signal for each line to implement the encryption effect of the video signal and low cost high quality.

And a characteristic configuration for this is the Automatic Gain Control and Synchronous Corrector to keep the synchronous signal and the gain of the input video signal constant, and the sample to make the DC stabilized output to be easily controlled at the rear end Sample / Hold, a first amplifier to ensure signal loss, and a first signal to restore the encrypted video signal to its original state and controlled by a reference signal applied by an offset control unit (Offset). A mux unit, a second amplifier unit for amplifying using a reference signal applied from the offset control unit, a third amplifier unit for changing the offset, and a control of a logic circuit unit (Logic Circuit) under the control of the video signal A second mux unit for inserting a reference signal at a position, a fourth amplifier unit for outputting an encrypted video signal, a fifth amplifier unit for amplifying, and a synchronization for separating a synchronous signal of the video signal A call separator, a logic circuit part for controlling the sample / hold part, the first mux part, and the second mux part by changing the offset of the offset control part of the reference signal under the control of the micom, and the current control state by the control of the micom. The display unit (Front Display) for displaying, and the control unit for allowing the microcomputer to operate by manual and remote (Remote) control.

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

2 is a block diagram of an image signal encryption circuit according to the present invention, in which the encryption circuit of the present invention consistently synchronizes the gain and gain of an image signal consisting of an input horizontal synchronization signal, a color burst signal, and a video signal. A stabilization circuit section 1, a sample / hold section 2 for making a direct current stabilized output by using one output of the stabilization circuit section 1 as input, and the above-mentioned A first amplifier part 3 for compensating for the loss of the signal through the sample / hold part 2, an offset control part 9 for generating a reference voltage as a direct current stabilization circuit under the control of the logic circuit part 10, and A first mux unit 4 controlled by a reference signal applied from the offset control unit 9 to restore an encrypted video signal to an original state by using the output of the first amplifier unit 3 as an input, and the first mux Output of negative (4) A multi-stage according to the change of the DC offset using the second amplifier part 5 to amplify the reference signal applied from the offset control unit 9 and the reference signal applied from the offset control unit 9. A third amplifier unit 6 for changing the signal level of the video signal multiplely by selectively changing the offset in conjunction with the channel selector 16 so as to select the IRE (the magnitude of the video signal); and the third amplifier unit ( 6) in conjunction with the channel selector 16 to select the multi-level IRE, the output of the second amplifier unit 5, the third amplifier unit 6 as the input under the control of the logic circuit unit 10 The image encrypted by inserting a reference signal at a predetermined position of the video signal and selecting a signal for each line of the video signal to change the signal level and the output of the second mux unit 7 as an input. A fourth amplifier section 8 for outputting a signal and the stabilization A fifth amplifier unit 14 which amplifies by using another output of the circuit unit 1 as an input, and a synchronous signal separator 15 which separates a synchronous signal of a video signal by using an output of the fifth amplifier unit 14 as an input. And the offset of the offset control unit 9 of the reference signal by the control of the microcomputer 11 by using the output of the synchronization signal separator 15 as a reference time. Logic circuit unit 10 for controlling the mux unit 4 and the second mux unit 7, a screen unit 13 for displaying the current control state under the control of the microcomputer 11, and the microcomputer 11 ) Can be manipulated by manual and remote control.

(A) is a waveform diagram of an input video signal, (b) is an output waveform diagram of a sample / hold section, (c) is an output waveform diagram of a sync signal separator, and (d) is an output waveform diagram of a first mux. , (e) is the output waveform of the second mux.

The following describes the operating state of the present invention configured as described above.

When a video signal consisting of the horizontal synchronization signal, the color burst signal and the video signal of FIG. 3A is input, the image signal is passed through the stabilization circuit unit 1 in order to keep the synchronization signal and the gain of the input video signal constant. The signal output from the stabilization circuit section 1 is adjusted so as to produce a stabilized output through the sample / hold section 2 as shown in FIG. The first amplifier 3 compensates for the loss at the front end, and the first mux 4 controls the reference signal of FIG. 3 (d) for restoring the encrypted video signal to its original state by the control of the offset controller 9. The reference signal is inserted at a predetermined position of the video signal of FIG. 3A by the control signal from the logic circuit unit 10. As shown in FIG. The offset of the reference signal receives the data from the logic circuit unit 10 under the control of the microcomputer 11 to change the DC offset. In this case, the change of the DC offset causes the third amplifier 6 to select a multi-level IRE. And channel selector 16 may be linked to select an IRE. The signal output from the third amplifier 6 is changed to the offset supplied from the offset control unit 9. The changed signal is formed as shown in the waveform of (e) of FIG. 3, which, when low, changes the brightness of the screen. The video signal encrypted through the fourth amplifier 8 is output. The signal output through the fourth amplifier 8 is transmitted from a broadcasting station through a modulator.

In addition, an image signal including the horizontal synchronization signal, the color burst signal, and the video signal of FIG. 3A is input to the synchronization signal separator 15 through the fifth amplifier 14, and the synchronization signal separator 15 is provided. The signal input to is formed as shown in (c) of FIG. 3 and is applied to the logic circuit unit 10 by separating the synchronization signal for use as a reference timing to the logic circuit unit 10. The microcomputer 11 controls the offset control unit 9, the sample / hold unit 2, the first mux 4, the channel selector 16, and the second mux 7 as control signals. In addition, the microcomputer 11 displays the current control state on the screen unit 13, and the microcomputer 11 may control the state by receiving a command from the controller 12 capable of manual and remote control.

As described in detail above, the television set as a receiver is used as a reference signal capable of filtering the signal of the video signal to change the DC value of the offset to control the brightness of the screen.

In the present invention, when the position of the reference signal is changed, the multi-level third amplifier and the channel selector can select the multi-level IRE by using the reference signal applied from the offset control unit. When the received video signal is received by the TV, it can be made black, and by selecting specific lines of the video signal, a certain line can be darkened, such that a certain interval of lines is formed on the TV screen.

Claims (3)

A stabilization circuit unit which makes the synchronization signal and the gain of the input video signal constant; A sample / hold section for producing a DC stabilized output; A first amplifier compensating for loss of a signal; An offset control unit for generating a reference voltage as a DC stabilization circuit under control of a logic circuit unit, and a first mux unit for restoring an encrypted video signal of the first amplifier unit to an original state and controlled by a reference signal of an offset control unit; A second amplifier unit amplifying using a reference signal applied from the offset controller; A third amplifier unit for changing an offset in association with a channel selector using a reference signal applied from the offset control unit; A channel selector configured to select an IRE of the third amplifier unit; A second mux unit for inserting a reference signal at a predetermined position of an image signal under the control of the logic circuit unit; A fourth amplifier outputting an encrypted video signal; A fifth amplifier unit configured to receive an output of the stabilization circuit unit; A synchronization signal separator for separating the synchronization signal of the image signal output from the fifth amplifier unit; A logic circuit unit for changing the offset of the offset control unit under the control of a microcomputer and controlling the sample / hold unit, the first mux unit, the channel selector, and the second mux unit; A screen unit which displays a current state under the control of the microcomputer; And a control unit capable of manipulating the microcomputer. The video signal encryption apparatus of claim 1, wherein the third amplifier changes the signal level of the video signal multiplely by interworking with a channel selector to select a multi-level IRE according to the change of the DC offset. The method of claim 1, wherein the second mux unit selects each line of the image signal by inputting the outputs of the second and third amplifier units and inserting a reference signal at a predetermined position of the image signal under the control of the logic circuit unit. Video signal encryption apparatus characterized in that the level is changed by.