KR930002116B1 - Wireless transmittion and receiver circuit seperating viewfinder - Google Patents

Abstract

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Description

Wireless transceiver for video camera with separate viewfinder

1 is a block diagram showing a wireless transmission circuit employed in the main body of a video camera according to the present invention.

2 is a block diagram showing a wireless receiving circuit employing a viewfinder of a video camera according to the present invention.

3A, 3B, 3C, 3D, and 3E are waveform diagrams for explaining an encoding operation of a wireless transmission circuit of a video camera in which the viewfinder is separated according to the present invention, and each of a TV broadcast signal, a separate vertical synchronization signal, and a gate pulse. These waveforms show delayed and waveform-converted sync signals, separated horizontal sync pulses, and encoded horizontal sync pulses.

4 is a detailed block diagram of a timing control unit employed in FIGS. 1 and 2;

5 is a detailed circuit diagram of an encryption means employed in FIG.

6 is a block diagram showing another embodiment of implementing the receiving circuit of the wireless viewfinder of the present invention using a microcomputer.

* Explanation of symbols for main parts of the drawings

10: CCD unit 20: preprocessing unit

30,120: video signal processor 31: luminance / color difference signal processor

32: video signal processor 40: 130: synchronization signal separation unit

50: encryption means 51: code generator

52: encoder 60,140: timing control unit

70 mixer section 80 modulator section

81: carrier oscillator 82: modulator

90 transmitter 91 amplifier

92 transmitter 93 transmission antenna

100: receiving unit 101: receiving antenna

102 receiver 110: demodulator

111: amplifier 112: detector

141: vertical sync signal 142: horizontal sync signal

143: A / D converter 144: counter

145: memory section 146: read / write control logic section

147: D / A Converter 148: Ambient Vibrator

149: gate circuit 150: decryption means

151: code generator 152: decoder

153: code reader 160: gate portion

170: display unit 171: video signal amplifier and synchronization signal separation unit

172: EVF, A: camera lens portion B: VCR deck portion

The present invention relates to a video camera in which the viewfinder unit is separated from the main body, and more particularly, to a wireless transmission / reception circuit employed in a video camera in which the main unit and the viewfinder of the video camera operate separately.

In general, a view finder of a video camera (also referred to as a cam corder) has a structure that is connected to a wire to be integrated with a main body of a video camera and operates while being supported in a housing, or the present applicant As in the detachable video camera described in the filing specification of No. 15765 filed with the Republic of Korea on October 31, 1989, the user's body with the viewfinder connected to the main body of the video camera by QNS connection and wired. It is configured to be mounted on a part of the. However, since all of them are streamlined, there is a problem that the user is inconvenient to use the video camera because there is a spatial limitation when shooting in an uncomfortable place, that is, underwater shooting or corners.

An object of the present invention is to provide a wireless transmission and reception circuit for employing the main body and viewfinder of the video camera configured to operate wirelessly by separating the main body and the viewfinder of the video camera. I am doing it.

Another object of the present invention is to superimpose a digital coding signal set by a user to a video signal by applying a coding technique in order to prevent interference of operation signals between video cameras configured to operate wirelessly, The present invention provides a wireless receiving circuit employed in the viewfinder unit for receiving a video signal only when the signal is equal to the value stored in the viewfinder unit.

In order to achieve the above objects, the present invention is configured by separating the viewfinder unit from the main body of the video camera, and converting the image signal of the subject input through the lens unit of the video camera installed on the main body side of the video camera to the electrical video signal. A CCD unit for converting into a; A preprocessing unit which receives the electrical signal and performs auto white balance adjustment, auto black balance adjustment, flare correction and gamma correction; A video signal processing unit which receives the preprocessed signal, separates it into luminance and color difference signals, and outputs a composite video signal; A sync signal separator for separating the video signal output from the video signal processor into vertical and horizontal sync signals; Encryption means for encoding a code set by the user via the keypad; A timing controller which receives a signal output from the encryption means and superimposes the encryption signal on a predetermined horizontal synchronization signal among the horizontal synchronization signals separated by the synchronization signal separation unit; A mixer unit for mixing the superimposed signal from the timing controller and the video signal from the video signal processor; A modulator for receiving a mixed signal from the mixer and modulating the carrier by a carrier having a specific frequency; And a viewfinder including a transmitter for amplifying a modulated video signal from the modulator in an amplifier and then wirelessly transmitting the modulated video signal to the viewfinder through a transmission antenna.

In addition, the present invention is configured to separate the viewfinder unit from the main body of the video camera in order to achieve the above objects, and receives the signal transmitted from the main body of the video camera through the reception antenna to the viewfinder of the video camera. Is a receiving unit; A demodulator for amplifying and detecting a received signal from the receiver; A video signal processor which processes the detected video signal from the demodulator; A sync signal separator for separating the video signal into vertical and horizontal sync signals; A timing controller for extracting an encryption signal superimposed on a predetermined horizontal synchronization signal separated by the synchronization signal separation unit; Decrypting means for comparing and reading the decoded signal from the timing controller with a code set by the user through the keypad; A gate section for turning on and off the video signal from the video signal processing section by the signal from the decoding means; A video signal is received from the gate path, amplified and synchronously separated, and a viewfinder including a display unit for displaying a video signal on a viewfinder screen is provided.

Hereinafter, with reference to the accompanying drawings, the configuration and operation of the wireless transmission and reception circuit of the video camera in which the viewfinder is separated according to the present invention will be described in detail.

1 is a block diagram showing a wireless transmission circuit employed in the main body portion of a video camera according to the present invention, and FIG. 2 is a wireless reception circuit employed in the viewfinder portion of a video camera according to the present invention. It is a block diagram.

According to FIG. 1, the reflected light from the subject passes through the lens portion A of the video camera, where the light entering the camera lens portion A is not shown in the figure, but the auto focus driver, the auto iris driver and the shutter are not shown. By the unit, and converted into an electric video signal by the CCD unit 10 as an image pickup device. The output signal converted by the CCD unit 10 into an electrical signal is sent to the video signal processing unit 30 by the auto white balance adjustment, the auto black balance adjustment, the flare correction, and the gamma correction by the preprocessor 20. After being separated into a signal, it is again output as a video signal containing a composite synchronization signal. The video signal processed in this way can be recorded or reproduced by directly sending to the VCR deck unit B together with the composite synchronization signal. At this time, the audio signal is not shown in the drawing, but is also applied to the VCR deck unit 100 through the microphone to be recorded. The video signal processing technique described above is already known to be used in the present invention, and thus a detailed description thereof will be omitted.

Hereinafter, a process in which the video signals are wirelessly transmitted and received from the main body of the video camera to the screen of the viewfinder in the video camera in which the viewfinder constituting the gist of the present invention is separated will be described in detail.

The video signal supplied from the video signal processor 30 is sent to the synchronization signal separator 40 so that the vertical and horizontal synchronization signals are separated and supplied to the timing controller 60. On the other hand, the user can input the code by the keypad in the encryption means 50, and input the desired password from the code generator 51 through the numeric keys 0 to 9 and other function keys. Accordingly, the code generator 51 generates a digital signal corresponding to the input password. The digital signal is input to the encoder unit 52, encoded, and supplied to the timing controller 60. The encoder 52 is a 10-to-4 bit encoder that converts any number from 0 to 9 of the code generator 51 into 4-bit digital data. The timing controller 60 superimposes the digital data signal from the encryption means 50 on a horizontal synchronous signal corresponding to 10H to 13H within a possible period of character signal overlap among the horizontal synchronous signals separated by the synchronous signal separator 40. Each horizontal synchronous pulse is set to be high when the reference pulse is above the reference pulse and low when the reference pulse is below the reference pulse. The signal superimposed by the timing controller 60 is sent to the mixer 70 and mixed together with the video signal from which the synchronization signal is not separated, and then supplied to the modulator 80, and the carrier oscillator 81 in the counter 80. Is modulated by the modulator 82 by a carrier of a particular frequency. This modulator 81 uses a balance modulator or other amplitude modulator. The video signal modulated by the modulator 80 is amplified by the amplifier 91 constituting the transmitter 90 and the transmitter 92 and then wirelessly transmitted from the transmit antenna 93 to the viewfinder.

According to FIG. 2, the transmission signal wirelessly transmitted from the transmission unit 90 of the video camera is received by the reception unit 100 including the reception antenna 101 and the receiver 102. The signal received from the receiver 100 is amplified through the amplifier 111 and supplied to the demodulator 110 detected by the detector 112. The video signal detected by the demodulator 110 is sent to the video signal processor 120 for processing. At this time, the detector 112 is determined according to the type of the demodulator. That is, it may be classified into a synchronous detector or an asynchronous detector. The signal processed by the video signal processor 120 is applied to the synchronization signal separator 130 to separate the vertical and horizontal synchronization signals, and the separated horizontal and vertical synchronization signals are input to the timing controller 140 together with the video signal. do. The timing controller 140 extracts the 4-bit digital signal carried in the horizontal synchronization signal of 10H to 13H within the possible period of the character signal overlapping of the first field among the horizontal synchronization signal, and sends it to the decoding means 150. On the other hand, the timing controller 140 extracts the 4-bit digital signal contained in the horizontal synchronization signal of 273H to 276H in the second field of the horizontal synchronization signal. The extracted 4-bit digital signal is sent to the decoder unit 152 in the decryption means 150, and compared with the secret code generated from the code generator 151 by the key pressed on the keypad of the viewfinder and compared by the code reader 153. do. When the secret code from the code generator 151 and the signal from the decoder unit 152 coincide with the result decrypted and read by the decryption unit 150, the high signal is output to the gate unit 160 to output the video signal. The video signal supplied from the processing unit 120 to the gate unit 160 is sent to the display unit 170 for display. In this case, the display unit 170 receives a video signal from the gate unit 160, amplifies the video signal, and separates the synchronous signal from the video signal amplifier and the synchronous signal separator 171, and an electronic view finder 172 (electronic view finder; EVF). It consists of. However, when the secret code from the code generator 151 and the signal from the decoder unit 152 do not match, the low signal is input to the gate unit 160, and the video signal supplied from the video signal processing unit 120 is Since the electronic device is blocked by the gate unit 160, no image is displayed on the electronic viewfinder unit 172.

Hereinafter, the operation of the wireless transmission / reception circuit of the video camera in which the viewfinder having the above configuration is separated will be described.

3a, 3b, 3c, 3d and 3e are waveform diagrams for explaining the encoding operation of the wireless transmission circuit of the video camera in which the viewfinder is separated according to the present invention, each of a TV broadcast signal, a separate vertical synchronization signal, and a gate pulse. A waveform diagram showing a delayed and waveform-converted sync signal, a separate horizontal sync pulse, and an encoded horizontal sync pulse, which acts as?

First, the present invention uses a part of the horizontal synchronization signal separated by the synchronization signal separation unit 40 shown in FIG. 1, and according to FIG. 3A, the TV broadcast signal has 525 scanning lines, and 2 per frame. Scanned by field separation. At this time, the 1H to 3H sections of the first field show equalization pulses, and the 4H to 6H sections show vertical synchronization pulses. In addition, the section in which data such as a character multiplexing signal can overlap is from 10H to 20H. A section in which a text signal can overlap in the next second field is 273H to 283H. Accordingly, as shown in FIG. 3A, in the signal for one field of the TW broadcast signal, the equalization pulse period 3H, the vertical synchronous signal pulse period 3H, the equalization pulse period 3H, and the character signal overlapping period 10H to within the vertical blanking period. 20H and the remaining video signal periods. In the second field, the vertical retrace start point is delayed by 0.5H from this field in timing. That is, start at 263H.

The present invention superimposes the signal encoded by the encryption means 50 using the signal period of 10H to 13H during the character signal overlapping period in the timing control section 60 of the wireless transmission circuit shown in FIG. The timing control unit 140 of the radio receiving circuit shown in FIG. 2 extracts and decodes the data contained in this section, and then checks whether the secret code set in the decryption means 150 of FIG. The screen is displayed on the EVF 172, which is a password reading function for preventing radio interference.

On the other hand, the vertical and horizontal synchronization signals separated by the synchronization signal separator 40 of FIG. 1 are input to the timing controller 60. In this timing controller 60, as shown in FIGS. 3B and 3B. The vertical synchronization signal is delayed by 6H and the gate pulse signal is increased by increasing the pulse width from 3H to 4H, and only 10H to 13H portions are extracted from the video signal input to the timing controller 60.

Next, the key signal pressed by the keypad in the encryption means 50 of FIG. 1 is generated from the code generator 51 and input to the encoder 52. FIG. This encoder section 52 is a 10-to-4 bit encoder, where the secret code is supplied to the timing controller 60 as a parallel 4-bit digital signal. According to the 4-bit digital signal of " 1 " or " 0 " input to the timing controller 60, the width of 10H to 13H of the horizontal synchronization signals extracted in units of 1H from the LSB to the MSB is increased or left as it is. In this case, as shown in FIGS. 3D and 3E, when the 4-bit digital signal is " l ", the width of the 10H to 13H horizontal synchronous signal is increased, and when it is " 0 " Output as a pulsed amplitude modulation (PAM) signal. As shown in FIG. 1, the PAM signal is mixed with the video signal in the mixer 70, then modulated in the balance modulator 80 or the AM modulator, and amplified through the transmitter 90 to transmit the antenna. Is sent from to the viewfinder.

Next, the receiving unit 100 on the viewfinder side receives the radio wave transmitted from the video camera body through the receiving antenna 101. This receiver uses a fixed receive tuner to tune to a constant frequency. As shown in FIG. 2, the signal received by the receiver 100 is amplified and detected through the demodulator 110, and the video signal processor 120 processes the signal passed through the demodulator 110. After inputting the vertical and horizontal synchronous signals through the same synchronization signal separator 130 as in the transmitting circuit, the input signal is input to the timing controller 140. In the timing controller 140, as in the timing controller 60 in the wireless transmission circuit on the main body of the video camera, a gate pulse having a delay of 6H for the vertical synchronization signal and a width increased to 4H is generated and inputted to the timing controller 140. The horizontal synchronizing signal in the 10H to 13H section is separated from the horizontal synchronizing signal. The horizontal synchronization signal thus separated is supplied to the decoder unit 152 in the decoding unit 150 of FIG. 1, in which the level of " 1 " and " 0 " After the voltage at the midpoint of the level is set as the detection reference voltage, the level of the horizontal synchronization signal from 10H to 13H is detected. At this time, if the level of the horizontal synchronization signal is greater than the set reference voltage level, it is detected as "1", and if it is smaller, "0", and the digital synchronization signal is a 10-bit digital signal in the same order as the encoding from LSB to MSB on the transmitting circuit side of the video camera main body. The data is reconverted and sent to the code reader 153. On the other hand, when the user inputs the same secret code as the user presses on the keypad in the decryption means 150, a 10-bit digital signal is input from the code generator 151 to the code reader 153. Accordingly, the code reader 153 reads whether the secret code signal input by the user and the encryption signal loaded on the video signal are identical, and when the two signals match, the coincidence signal, that is, the high signal, is supplied to the gate unit 160. In addition, the gate unit 160 sends a video signal, that is, a TV video signal, to the EVF 172 according to the match signal to be displayed on the screen.

In addition, if the two signals do not match, the gate unit 160 blocks the video signal, thereby automatically preventing interference with the video signal input from another wireless video camera.

Next, the internal structure of the timing controller employed in the transmission and reception circuit of the present invention will be described.

4 is a detailed block diagram of a timing control unit employed in FIGS. 1 and 2.

4 illustrates an example in which the reception circuit is employed to explain the operation of the timing controller 140.

Referring to FIG. 4, the vertical synchronization signal 141 and the horizontal synchronization signal 142 separated by the synchronization signal separation unit 130 are input to the A / D converter 143 and the counter 144, respectively. At this time, the horizontal synchronization signal includes an equalization pulse, and two moving pulses are counted by being input to the counter 144 as one horizontal synchronization signal. One output of the counter 144 provides a clock signal CK to the A / D converter 143 to sample the vertical synchronous signal input to the A / D converter 143 to convert the digital signal into a digital signal. Is output to the memory unit 145 and is stored at a specified address addr of the memory unit 145. On the other hand, one output of the counter 144 is sent to the read / write control organization unit 146, which writes signals in the 1H to 6H sections and reads from 7H. The output of 146 is sent to the memory, and the vertical synchronous data written by the write signal is read by the read signal and sent to the D / A converter 147. In this case, the high signal from 1H to 6H and the low signal from 7H may be directly output from the counter 144 to the memory unit 145. Next, the vertical synchronization signal input to the D / A converter 147 receives the clock signal CK from the counter 144 and converts it into an analog signal. The vertical synchronization signal converted into this analog signal is delayed by 4H width by the monostable multivibrator (M / M) 148 and applied to one terminal of the gate portion 160. The gate unit 160 receives the counting output of the counter 144, i.e., the signals of 7H to 13H, as inputs to other terminals, thereby timing the D / A-converted delayed vertical synchronization signal and the original horizontal synchronization signal in a timing manner. It is a correction circuit for matching. That is, only signals from 7H to 13H are allowed to pass. In this case, the counter 144 is composed of a normal binary counter. Next, the gate pulse passing through the gate circuit 149 passes only 10H to 13H portions of the horizontal synchronization signal.

Next, as shown in FIG. 5, the detailed configuration of the encryption means employed in FIG. 1 of the present invention will be described.

According to FIG. 5, the encryption means 50 employed in FIG. 1 of the present invention comprises a code generator 51 and an encoder unit 52. As shown in FIG.

The key signal that the user presses on the keypad 51 of the transmission circuit in the video camera main body is a 10-bit digital signal, which is converted into 4 bits by the logic circuit 52. Each of the converted digits passes through the AND gate in synchronization with the horizontal synchronization signals 10H to 13H, and when high, the DC voltage is output by the DC bias circuit, and is added to the horizontal synchronization signals 10H to 13H by the adder. The timing controller 60 is supplied to the timing controller 60. In this timing controller 60, the encryption signal from the encryption means 50 is loaded on the horizontal synchronization signals 10H to 13H of the video signal. On the other hand, the configuration and operation of the decoder unit 152 and the code generator 151 constituting the decryption means 150 of the radio receiver circuit on the viewfinder side of the present invention are the case of the encryption means 50 of the radio transmitter circuit described above. It is very similar to, so detailed description is omitted.

In addition, the code generator, decoder unit, encoder unit, code reader, and timing control unit employed in the wireless transmission / reception circuit constituting the present invention have the same function by software embedded in a microcomputer as shown in FIG. Can be done.

6, the configuration of the present invention using a microcomputer is briefly shown.

Referring to FIG. 6, in response to a key input from the keyboard, the microcomputer adds an encoding signal in the 10H to 13H section of the horizontal synchronization signal, gate-pulses the vertical synchronization signal in synchronization with the horizontal synchronization signal, and then through the gate element. Gating with the TV video signal. The gating signal is added to the horizontal synchronizing signal to which the encoding signal is added and added by the adder, modulated and amplified by the modulator, and transmitted by the transmitting unit through the transmitting antenna. Although the detailed description of the present invention using the microcomputer as described above and the operation description through the flowchart are omitted, it can be said that the present invention is comprehensively included in the scope of the present invention even though the claims of the present invention are not described.

As described above, the wireless transmission / reception circuit of the video camera in which the viewfinder is separated according to the present invention is applied to a conventional video camera, and the video camera main body and the viewfinder may be used in places where shooting is difficult or in places subject to spatial limitations. Not only can it be taken separately, but also allows the user to easily set an encryption code through the keypad so as not to interfere with a video signal input from another wireless video camera.

Claims (7)

A CCD unit which separates the viewfinder from the main body of the video camera and converts the image signal of the subject input through the lens of the video camera into an electrical signal, and receives the electrical signal to adjust the auto white balance and auto black balance. The video signal processor on the main body side of the video camera having a preprocessor for adjustment, flare correction, and gamma correction, and a video signal processor for receiving the preprocessed signal and processing a luminance / color signal and then outputting a composite video signal. A synchronization signal separation unit for separating the video signal output from the vertical and horizontal synchronization signals; Encryption means for encoding a code set by the user via the keypad; A timing controller which receives a signal output from the encryption means and superimposes the encryption signal on a predetermined horizontal synchronization signal among the horizontal synchronization signals separated by the synchronization signal separation unit; A mixer unit for mixing the superimposed signal from the timing controller and the video signal from the video signal processor; A modulator for receiving a mixed signal from the mixer and modulating the carrier by a carrier having a specific frequency; And a transmitter for amplifying the modulated video signal from the modulator in an amplifier and wirelessly transmitting the modulated video signal to the viewfinder through a transmission antenna. 2. The apparatus of claim 1, wherein the timing controller comprises: a counter for counting and outputting a horizontal synchronization signal separated from the synchronization signal beak unit; An A / D converter for receiving a clock signal from the counter and converting the analog vertical synchronization signal separated by the synchronization signal separation unit into digital; A memory unit for storing the digitally converted signal at a designated address of the memory by an address signal from a counter; A read / write control logic section which sends a read / write logic signal to the memory section by an output from the counter to read / write the vertical synchronization signal stored in the memory; A digital-to-analog converter (D / A converter) for analog-converting the digital vertical synchronous signal read / written from a memory according to the control signal of the read / write control logic unit according to the clock signal from the counter; A monostable multivibrator for delaying the analog-converted vertical synchronization signal from the D / A converter by a predetermined width; And a gate circuit for passing only a predetermined horizontal synchronization signal by gating an output from the counter and an output from the multivibrator. 2. The apparatus of claim 1, wherein the encryption means comprises: a code generator for generating a secret code by a number from 0 to 9 input by a user through a keypad; And an encoder unit for encoding a secret code from the code generator and supplying the secret code to the timing controller. A receiving unit configured to separate the viewfinder from the main body of the video camera, and to receive a signal transmitted wirelessly from the main body of the video camera to the viewfinder side of the video camera through an antenna; A video signal processing unit for processing the detected video signal from the receiving unit; A sync signal separator for separating the video signal into vertical and horizontal sync signals; A timing controller for extracting an encryption signal superimposed on a predetermined horizontal synchronization signal separated by the synchronization signal separation unit; Decrypting means for comparing and reading the decoded signal from the timing controller and the code set by the user through the keypad; A gate section for turning on and off a video signal from the video signal processing section by a signal from the decoding means; And a display unit for receiving the video signal from the gate unit, amplifying and synchronously separating the video signal, and displaying the video signal on the screen of the electronic viewfinder. The apparatus of claim 4, wherein the timing controller comprises: a counter configured to receive and count a horizontal synchronization signal separated from the synchronization signal separator; An A / D converter for receiving a clock signal from the counter and converting the analog vertical synchronization signal separated by the synchronization signal separation unit into digital; A memory unit for storing the digitally converted signal at a designated address of the memory by an address signal from a counter; A read / write control logic section which sends a read / write logic signal to the memory section by an output from the counter to read / write a vertical motion signal stored in the memory; A D / A converter for analog-converting a digital vertical synchronization signal read / write from a memory according to a control signal of the read / write control logic unit according to a clock signal from the counter; A monostable multivibrator for delaying the analog-converted vertical synchronization signal from the D / A converter by a predetermined width; And a gate circuit for passing only a predetermined horizontal synchronization signal by gating an output from the counter and an output from the multivibrator. 5. The apparatus of claim 4, wherein the decryption means comprises: a code generator for generating a secret code by a number from 0 to 9 input by a user through a keypad; A decoder for decoding the encryption code carried in the horizontal synchronization signal from the timing controller; And a code reader for receiving the output from the code generator and the output from the decoder and comparing the output signals to the gate to compare the output signals to the gate. . A CCD unit configured to separate the viewfinder from the main body of the video camera, and convert the image signal of the subject input through the lens of the video camera to an electric signal on the main body side of the video camera; A pre-processing unit for receiving the electric signal and performing auto white balance adjustment, auto black balance adjustment, flare correction and gamma correction; A video signal processor which receives the previously processed signal and processes luminance / color signals to output a composite video signal; A sync signal separator for separating the video signal into vertical and horizontal sync signals; Encryption means for encoding a code set by the user via the keypad; A timing controller which receives a signal input from the encryption means and superimposes the encryption signal on a predetermined horizontal synchronization signal among the horizontal synchronization signals separated by the synchronization signal separation unit; A mixer unit for mixing the superimposed signal from the timing controller and the video signal from the video signal processor; A modulator for receiving a mixed signal from the mixer and modulating the carrier by a carrier having a specific frequency; And a wireless transmitting circuit comprising a transmitting unit for amplifying the modulated video signal from the modulator in an amplifier and wirelessly transmitting the modulated video signal to the viewfinder through a transmitting antenna, the main body of the video camera on the viewfinder side of the video camera. A receiving unit which receives a signal transmitted by radio from a receiving antenna; A video signal processing unit for processing the detected video signal from the receiving unit; A sync signal separator for separating the video signal into vertical and horizontal sync signals; A timing controller for extracting an encryption signal superimposed on a predetermined horizontal synchronization signal separated by the synchronization signal separation unit; Decrypting means for comparing and reading the decoded signal from the timing controller and the code set by the user through the keypad; A gate section for turning on and off the video signal from the video signal processing section by the signal from the decoding means; And a wireless receiving circuit comprising a display section for receiving a video signal from the gate section, amplifying and synchronously separating the video signal, and displaying a video signal on the screen of the viewfinder.

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