JP2001177821A - Control signal mask method and control signal mask circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control signal mask method and a control signal mask circuit where a burst level for a prescribed period is extracted from a digitally converted burst signal, a reference pedestal level is calculated and outputted by the burst level and a mask signal with the reference pedestal level is superimposed on a digital image signal. SOLUTION: A pedestal level extracts means 5 converts a color video signal into a digital image signal and extracts a burst level for a horizontal period where a control signal is superimposed in the digital signal based on an extract signal from an extract signal generating means, a mask signal generating means 6 calculates an outputs a reference pedestal level by the extracted burst level, generates and outputs a mask signal with the reference pedestal level, a mask signal superimposing means 6 switchingly superimposes a digital control signal part on the mask signal and converts the digital image signal into an analog video signal and provides as output of it.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control signal superimposed on a color video signal with a control signal which is input from a camera unit and the like and in which a control signal such as a camera number and control data is superimposed during a vertical blanking period. Instead, the present invention relates to a control signal masking method and a control signal masking circuit which are output by replacing a pedestal level mask signal. More specifically, a mask signal is generated by extracting a pedestal level from a digitally converted burst signal. Things.

[0002]

2. Description of the Related Art The configuration and operation of a control signal mask circuit will be described with reference to a block diagram of a main part of a control signal mask circuit according to the prior art shown in FIG. 5 and a signal waveform diagram shown in FIG. The plurality of surveillance cameras 1 are mounted on a camera controller 1a that can drive a pan tilt or the like. These cameras are connected to a camera control / switching device 2 installed in a monitoring office or the like. The camera control / switching device 2 selects and switches a plurality of camera signals and outputs the signals to the monitor M, and also controls the camera 1 and the camera control device 1a. The supervisor uses the camera operation unit 2c to operate the camera control device 1a such as a turning device and the zoom lens of the camera. The control signal generating means 2d generates a control signal and inputs it to the control signal superimposing means 2a. The control signal superimposing means 2a superimposes the control signal in the form of a code signal at a predetermined pedestal position in a vertical retrace period of the video signal from the camera 1, sends the control signal back to the camera side, and superimposes the control signal. Signal (Figure 2
(B) is output to the monitor M. The camera 1 separates and demodulates the superimposed control signal to obtain a control signal of the camera control device 1a. Further, in the camera 1, sensor data such as an attached sensor signal or an image sensor signal extracted from a camera image may be superimposed on a pedestal position in another horizontal period.

A video signal on which a superimposed signal such as a control signal and sensor data is superimposed is sent to a monitor M or a recording device. However, when it is desired to add a transmission line test signal or another analog data to the superimposed signal portion, a control signal masking circuit 3 or a control signal masking device is added to the line, and after the superimposed signal portion is deleted, the mask signal is removed. Is added. More specifically, the video signal is used to detect V
D and HD are extracted, and a pseudo synchronizing signal generating means 8 generates a synchronizing signal for a vertical blanking period. Next, the mask signal superimposing means 7 superimposes the pedestal signal in the mask period on the video signal. The pedestal level of this pseudo sync signal is a level fixed by circuit constants, and does not match the pedestal level of the video signal from the camera (FIG. 2).
(D)) often occurs. When the average gradation level of the video signal changes, the pedestal level often fluctuates in a DC manner. For this reason, the added pedestal signal is shown in FIG.
As shown in (e), the signal level becomes a mask signal that does not match the pedestal level of the input video signal, and there is a problem that transmission line test signals and analog data cannot be added correctly.

[0004]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention extracts a burst level for a predetermined period from a burst signal converted into a digital image signal, and uses the burst level as a reference pedestal level. And a control signal masking circuit and a control signal masking circuit for superimposing the control signal on a digital image signal as a mask signal after calculating and outputting the same.

[0005]

A color video signal with a control signal in which a control signal such as a camera number of a monitoring camera and control data of the camera is superimposed is input to VBL, and a control superimposed on the VBL of the color video signal is input. In a method of masking a control signal which is replaced with a mask signal of a pedestal level and output, the input color video signal is converted into a digital image signal, and a burst is obtained from the digital image signal in the horizontal period in which the control signal is superimposed. Pedestal level extracting means for extracting a level;
HD, a synchronization separation unit for separating and generating a CLK phase-locked to a burst, a mask signal generation unit for generating a mask signal based on a burst level extracted by a pedestal level extraction unit, and a digital image signal, A pedestal level extracting unit converts a color video signal into a digital image signal by using a control signal mask circuit configured by a mask signal superimposing unit that superimposes a mask signal instead of the control signal unit of the control signal unit. Based on the extracted signal, the burst level of the horizontal period in which the control signal is superimposed is extracted, and the mask signal generation unit calculates the extracted burst level based on an operation function previously registered and stored in an operation function memory. After calculating and outputting the reference pedestal level, a mask signal of the reference pedestal level is generated. Outputs the mask signal superimposing means,
The control signal portion of the digital image signal is switched and superimposed on the mask signal, and the digital image signal on which the mask signal is superimposed is converted and output as an analog video signal.

The extraction signal generation means generates an extraction signal for extracting a burst level at a zero crossing point of a burst, or a detection means for a burst is provided to generate an extraction signal for extracting a burst level for an entire burst period.

A specific zero-cross point level calculation function that uses the burst level at the specific zero-cross point as a reference pedestal level is registered and stored in the mask signal generation means. The average zero-cross point that uses the average value of the burst levels at all zero-cross points as the reference pedestal level Registering and storing the level calculation function, registering and storing the average burst level calculation function using the average value of the burst levels during the entire burst period as the reference pedestal level, and storing the average burst level calculation function during the specific burst period as the reference pedestal level Registering and storing a level calculation function, registering and storing an initial burst level calculation function that sets the average value of the burst level in the horizontal period in which the first control signal is superimposed on the VBL as the reference pedestal level in the entire control signal superimposition period, or , Burst level for the entire burst period A maximum / minimum burst level calculation function which is used as a reference pedestal level to obtain an average value from the maximum value and the minimum value of the data is registered and stored.

[0008] A color video signal with a control signal in which a control signal such as a camera number of a monitoring camera and control data of the camera is superimposed is input to the VBL, and the control signal superimposed on the VBL of the color video signal is replaced with a pedestal. In a method of masking a control signal to be output in place of a mask signal of a level, an input color video signal is converted into a digital image signal, and a shift register is used from the digital image signal in a horizontal period in which the control signal is superimposed. Pedestal level extracting means for extracting a burst level, synchronous separating means for separating and generating VD, HD, and CLK phase-locked to a burst from a color video signal, and generating a mask signal based on the extracted burst level A mask signal generating means, and a digital image signal control signal, A pedestal level extracting means converts a color video signal into a digital image signal by using a control signal mask circuit comprising a mask signal superimposing means for superimposing a mask signal instead of a signal portion, and converts the digital image signal into a shift register. Means for extracting a burst level in the horizontal period in which the control signal is superimposed, and the mask signal generating means calculates the burst level extracted by the pedestal level extracting means based on an arithmetic function set by the extracting function setting means. After calculating and outputting the reference pedestal level, a mask signal of the reference pedestal level is generated and output. The mask signal superimposing means switches and superimposes the control signal portion of the digital image signal on the mask signal, and the mask signal is superimposed. The digital image signal is converted to an analog video signal and output.

The extraction function setting means sets an average burst level calculation function that sets an average value of burst levels during the entire burst period as a reference pedestal level. All zero crosses that set an average value of burst levels at all zero cross points as a reference pedestal level. A point burst level calculation function is set, or a peak burst level calculation function is set, in which the average value of the burst levels at 90 ° and 270 ° of the burst phase is set as the reference pedestal level.

A control signal masking circuit inputs a color video signal with a control signal in which a control signal such as a camera number of a monitoring camera and control data of the camera is superimposed on the VBL, and controls the color video signal superimposed on the VBL. Instead of a signal,
In a mask circuit of a control signal which is output after replacing the mask signal of the pedestal level, VD,
Synchronization separation / PLL section for separating and generating HD and CLK phase locked to a burst, A / D for converting the input color video signal into a digital image signal, and burst signal extraction for extracting a burst from the color video signal An extraction function memory for registering and storing an extraction function for burst level extraction; an extraction signal generating means for generating a burst level extraction signal based on the extraction function from the extracted burst, VD, HD and CLK; A pedestal level extraction unit having a pedestal extraction unit for extracting a burst level from an image signal using a burst level extraction signal; a mask timing generation unit for generating a timing of a mask signal from VD, HD, etc .; An arithmetic function memory that stores and stores arithmetic functions, and an arithmetic function Then, after calculating the burst level and calculating and outputting the reference pedestal level, a mask signal generating means having an additional pedestal calculating section for generating a mask signal of the reference pedestal level, and a control signal section deleted from the digital image signal A mask signal superimposing section for replacing and superimposing a mask signal; and a D / D converter for converting and outputting the digital image signal on which the mask signal is additionally superimposed into an analog video signal.
A and a mask signal superimposing means having A.

[0011] The extraction signal generation means is configured to detect a zero-cross point pulse of the burst from the burst extracted by the burst signal extraction unit by using a zero-cross point detection unit that detects a zero-cross point pulse of the burst and an extraction function registered and stored in an extraction function memory. A detection unit for linearly detecting the burst extracted by the burst signal extraction unit, the detection unit comprising a sampling pulse generation unit for generating a burst level extraction signal from a pulse, VD, HD, and the like; A waveform shaping section for slicing to form a burst period signal, and a sampling pulse generating section for generating a burst level extraction signal from a burst period signal, VD, HD, etc. using an extraction function registered and stored in an extraction function memory. Or, after the burst extracted by the burst signal extraction unit is shaped into a rectangular wave pulse, N-ary (N = 0, 1, 2) count through N
It is composed of a binary counter and an N-ary setting unit for setting the N-ary of the N-ary counter.

A specific burst storing and registering a zero cross point extraction function for extracting a digital image signal of a zero cross point of a burst in an extraction function memory, and storing and registering a full burst extraction function for extracting a digital image signal of all burst periods. A specific burst extraction function for extracting a digital image signal of a period is stored and registered. A stable period burst extraction function for extracting a digital image signal only for a stable period of burst amplitude is stored or registered, or a first control signal is superimposed on VBL. The first horizontal period burst extraction function for extracting the digital image signal of only the horizontal period is stored and registered.

The control signal masking circuit inputs a color video signal with a control signal in which a control signal such as a camera number of a monitoring camera and control data of the camera is superimposed on the VBL, and controls the color video signal superimposed on the VBL. Instead of a signal,
In a mask circuit of a control signal which is output after replacing the mask signal of the pedestal level, VD,
A synchronization separation / PLL unit for separating and generating an HD and a CLK phase-locked to a burst, an A / D for converting the input color video signal into a digital image signal,
A burst signal extraction unit for extracting a burst from a color video signal, and an AND for outputting CLK only during a burst signal period
A gate, an arbitrarily configurable N-ary counter for counting the CLK output from the AND gate, and shifting the digital image signal by the CLK to obtain burst phases 0, 90, 1
Pedestal level extracting means having a shift register for outputting digital image signals at 80 and 270 degree points, and an addition operation unit for performing an addition operation on the digital image signal output from the shift register based on a setting output of an N-ary counter;
A mask timing generation unit for generating the timing of the mask signal from D, HD, etc., and a division operation of a reference pedestal level on a digital image signal output from the addition operation unit using a predetermined extraction function. A mask signal generating means having a division operation unit for generating a signal, an extraction function setting unit for setting an extraction function such as an N-ary counter and the division operation unit, and a control signal unit for deleting a control signal unit from the digital image signal. And a D / D converter that converts a digital image signal on which a mask signal is added and superimposed into an analog video signal and outputs the analog image signal.
A and a mask signal superimposing means having A.

An extraction function setting unit sets an average burst level extraction function in which N is an average value of burst levels in all burst periods as a reference pedestal level. , Or N is set to 90 degrees of the burst phase and 2
A peak burst level extraction function that sets the average value of the burst level at the 70-degree point as a reference pedestal level is set.

[0015]

FIG. 1 is a schematic block diagram of a monitoring system used in a control signal masking method according to the present invention. FIG. 2 is a main part block diagram of a first embodiment of the control signal mask circuit according to the present invention. FIG. 3 is a signal waveform diagram for explaining the operation of the control signal mask circuit according to the present invention. FIG.
FIG. 7 is a block diagram of a main part of a second embodiment of the control signal mask circuit according to the present invention. The background and object of the present invention will be outlined with reference to FIGS. FIG. 2A is an enlarged view of an input video signal from the camera switching unit 2b, particularly, VBL (vertical retrace period). The control signal of the camera section is superimposed 1H (horizontal) period ahead of the end of the VD (vertical synchronization signal) and the equivalent pulse. The superimposition period varies from 1 to 8H depending on the system. (B) is a waveform obtained by removing the superposition control signal and adding a pedestal level mask signal.
It is a target output waveform of the present invention. In the prior art described above, the sync separation unit (FIG. 5 (4)) converts the input video signal into V
After synchronizing signals such as D and HD are separated, a pseudo synchronizing signal for replacement is generated by the pseudo synchronizing signal generation means (FIG. 5 (8)) based on the synchronizing signal, and the mask period of the signal is cut off to obtain a mask signal (c). ). The level of the pseudo synchronizing signal is a constant value determined by the circuit constant. The video signal from the camera switching device 2 cannot be kept at a constant level due to factors such as variations among cameras, distortion in transmission lines, and differences in average luminance of captured images. If there is a high level input, the pseudo sync signal is relatively low in level (d), which means that the pedestal level in the mask period falls to the sync signal level as shown in (e).

In order to solve this phenomenon, in the present invention,
Focusing on the color burst (hereinafter referred to as burst) portion, the level of the burst operating point (hereinafter referred to as burst level)
The reference pedestal level is extracted from it. A mask signal is generated based on the reference pedestal level.

The control signal masking circuit 3 according to the present invention
A pedestal level extracting unit 5 for converting a color video signal input from the camera switching unit 2b into a digital image signal and extracting a burst level from the digital image signal in the horizontal period on which the control signal is superimposed, and V from the color video signal
D, HD, a sync separation unit 4 for separating and generating a CLK phase-locked to a burst, a mask signal generation unit 6 for generating a mask signal based on a burst level extracted by a pedestal level extraction unit 5, a digital image signal, It is roughly composed of a mask signal superimposing means 7 for superimposing a mask signal instead of a digital control signal.

The detailed configuration of the control signal mask circuit according to the present invention will be described with reference to FIG. The control signal mask circuit of the first embodiment includes a synchronization separation / PLL unit 4 for separating and generating VD, HD, and CLK phase-locked to a burst from a color video signal, and converts the input color video signal into a digital image signal. A / D 5a to be converted, burst signal extractor 5 for extracting burst from color video signal
d, an extraction function memory 5f in which an extraction function for burst level extraction is registered and stored, an extraction signal generating means 5e for generating a burst level extraction signal based on the extraction function from the extracted burst, VD, HD and CLK, a digital image A pedestal level extracting means 5 having a pedestal extracting section 5b for extracting a burst level from a signal using a burst level extracting signal; a mask timing generating section 6c for generating a timing of a mask signal from VD, HD, etc .; An operation function memory 6b that registers and stores the operation function of the above, an additional pedestal operation unit 6a that calculates the burst level based on the operation function, calculates and outputs a reference pedestal level, and then generates a mask signal of the reference pedestal level. A mask signal generating means 6 having Remove the control signal unit from the image signal,
The standard configuration includes a mask signal superimposing section 7a for replacing and superimposing a mask signal, and a mask signal superimposing means 7 having a D / A 7b for converting and outputting a digital image signal on which the mask signal is additionally superimposed into an analog video signal.

Further, the above-mentioned extraction signal generating means 5e
Three types are proposed, the first and second embodiments are (b)
The third embodiment is shown in (c). The extraction signal generating means 5e of the first embodiment includes a zero-cross detection unit 5e1 for detecting a zero-cross point pulse of the burst from the burst extracted by the burst signal extraction unit 5d, and an extraction function memory 5
a sampling pulse generating unit 5e4 for generating a burst level extraction signal from a zero-crossing point pulse, VD, HD, or the like using an extraction function registered and stored in f; Is a detector 5e for linearly detecting the burst extracted by the burst signal extractor 5d.
2. A waveform shaping section 5e3 for slicing the linearly detected waveform at a predetermined level to form a burst period signal, and a burst period signal, VD, HD using an extraction function registered and stored in an extraction function memory 5f. It is composed of a sampling pulse generator 5e4 for generating a burst level extraction signal.

The extraction signal generating means 5 e of the third embodiment
Sets the N-ary (N = 0, 1, 2,...) Count through N-ary counter 5e5 and N-ary counter 5e5 after shaping the burst extracted by the burst signal extraction unit 5d into a rectangular wave pulse. It is composed of an N-ary setting unit 5e6 and the like.

A circuit operation and a method of generating a mask signal will be described along the flow of processing of an input video signal. Sync separation &
The PLL unit 4 separates the VD, HD, color bust signal, and the like from the input video signal, and generates a 4 fsc (four times the color carrier frequency) CLK (sampling clock signal) phase-locked to the color bust signal by the PLL circuit. I do. FIGS. 3G and 3H show the relationship between burst and CLK. The input video signal is converted to a digital image signal by an A / D 5a operating at a 4 fsc CLK. One of the digital image signals is input to a pedestal level extraction unit 5b, and the other is input to a mask signal superimposition unit 7a. The image data for each pixel of the digital image signal is CLK
Is the video signal level at the time of rising. FIG. 3 (L) shows an analog display of the image data of the burst portion. T0 is originally a zero crossing point (phase 0 °), but is sampled and held at a level higher than the pedestal level because the burst is slightly disturbed at the rising edge of the burst. T90 (phase 90
°) is the plus peak level of the burst, T180 (phase 180 °) is the zero cross level of the burst, T180
(Phase 270 °) represents the negative peak level of the burst. At T360, the phase returns to 0 °, indicating the zero cross level of the burst.

The pedestal level extractor 5b extracts the image data of the burst part based on the extraction signal from the extraction signal generator 5e, and inputs the image data to the additional pedestal calculator 6a. The first method of extracting the burst level is a method of extracting only the zero-cross level of the burst based on the zero-cross pulse from the zero-cross detector 5e1. The second method is to extract all burst levels in all burst periods based on the burst detection pulse from the waveform shaping unit 5e3. The extraction method selected by the extraction signal generating means 5e is registered and stored in the extraction function memory 5f as an extraction function in advance. Other than the methods described above, the fixed duration of the burst,
An extraction method such as a burst amplitude stabilization period or only a horizontal synchronization period of the first control signal superimposition can be selectively registered.

The additional pedestal calculation section 6a converts the image data of the burst section from the pedestal level extraction section 5b into
The reference pedestal level is calculated and output using a calculation function registered and stored in the calculation function memory 6b, and pedestal data (FIG. 3F) in which the reference pedestal level is maintained for a control signal period is generated. This pedestal level data is supplied to the mask signal superimposing section 7a only during the control signal period.
The image signal data from D5a is replaced and superimposed.

The operation functions registered and stored in the operation function memory 6b are a specific zero-cross point level operation function that uses the burst level at a specific zero-cross point as a reference pedestal level, and an average value of burst levels at all zero-cross points as a reference pedestal level. An average zero-crossing point level calculation function, an average burst level calculation function that uses the average value of burst levels for all burst periods as a reference pedestal level, a specific burst level calculation function that uses the average burst level for a specific burst period as a reference pedestal level, VBL
The first burst level calculation function that sets the average value of the burst level in the horizontal period in which the first control signal is superimposed as the reference pedestal level in the entire control signal superimposition period, the average value from the maximum and minimum values of the burst level in the entire burst period It is possible to select the maximum / minimum burst level calculation function used as the reference pedestal level.

The control signal mask circuit of the second embodiment will be described mainly with reference to FIG. 4, focusing on the differences from the first embodiment. The control signal mask circuit of the second embodiment converts the input color video signal into a digital image signal by A
/ D5a, a burst signal extractor 5d for extracting a burst from a color video signal, an AND gate 5d1 for outputting CLK only during the burst signal period, an arbitrarily configurable N-ary counter 5i for counting the CLK output from the AND gate 5d1, a digital A shift register 5g that shifts the image signal by CLK and outputs a digital image signal at points 0, 90, 180, and 270 degrees of the burst phase, and outputs the digital image signal output from the shift register based on the setting output of an N-ary counter 5i. A pedestal level extraction means 5 having an addition operation unit 5h for performing an addition operation; a mask timing generating unit 6c for generating the timing of the mask signal from VD, HD, etc .; After dividing the reference pedestal level using A mask signal generation unit 6 having a division operation unit 6d for generating a mask signal at a reference pedestal level, an N-ary counter 5i, an extraction function setting unit 6e for setting an extraction function such as the division operation unit 6d, and the like are separately provided. ing.

In the second embodiment, the extraction method is A / D5
The image data of the digital image signal converted and output from a is input to the shift register 5g which is transferred at a 4 fsc CLK. The shift register 5g has output terminals (270, 180, 90, 0) in units of CLK, and burst levels at timings of 0, 90, 180, and 270 degrees in burst phase are extracted.

The AND gate 5d1 performs a logical product of the burst period and CLK, and outputs a burst CLK only from the start to the end of the burst. The burst CLK is counted and output by an N-ary counter 5i capable of setting an arbitrary N-ary number. The addition operation unit 5h performs the addition operation by selecting the burst levels of 0, 90, 180, and 270 degrees in the burst phase from the shift register 5g according to the count setting of the N-ary counter 5i, and reduces the addition burst level. Output. The division operation unit 6d performs a division operation on the added burst level based on the setting of the extraction operation setting unit 6e, and outputs a reference pedestal level. In other words, the divisor is set and the average value is calculated based on how many burst levels have been added by the above-described addition calculation section 5h. Hereinafter, the method of generating the mask signal is the same as in the first embodiment, and a description thereof will be omitted.

The extraction function that can be set in the extraction calculation setting unit 6 e is an average burst level extraction function of N = 0 (an average value of burst levels in all burst periods is set as a reference pedestal level), and N = 1 (zero cross point point). Zero-cross point burst level extraction function of the average value of the burst level as the reference pedestal level, N = 2 (9 of the burst phase)
The average value of the burst levels at the 0-degree and 270-degree points is defined as a reference pedestal level).

[0029] In addition to the first and second embodiments described above, many specific circuit configurations are conceivable but omitted.
However, a reference pedestal level is generated from the image data of the burst portion of the digital image signal, and after superimposing and replacing the control signal superimposing portion of the image signal, the analog video signal on which the mask signal is superimposed by the D / A 7b is output. The method is the basis of the present invention.

[0030]

The present invention is embodied as described above, and has the following effects. The pedestal level extracting means 5 converts a color video signal into a digital image signal, and extracts a burst level in a horizontal period in which a control signal is superimposed on the basis of the extracted signal from the extracted signal generating means,
The mask signal generation means 6 calculates and outputs the extracted burst level to a reference pedestal level based on a calculation function previously registered and stored in a calculation function memory, and then generates and outputs a mask signal of the reference pedestal level. The mask signal superimposing unit 7 proposes a control signal masking method and a control signal masking circuit for switching and superposing a digital control signal portion on the mask signal and converting and outputting a digital image signal on which the mask signal is switched and superimposed into an analog video signal. did it.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a monitoring system used for a control signal masking method according to the present invention.

FIG. 2 is a main part block diagram of a first embodiment of a control signal mask circuit according to the present invention.

FIG. 3 is a signal waveform diagram for explaining the operation of the control signal mask circuit according to the present invention.

FIG. 4 is a main part block diagram of a second embodiment of the control signal mask circuit according to the present invention.

FIG. 5 is a block diagram of a main part of a control signal mask circuit according to a conventional technique.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 camera 1a camera control device 2 camera control / switching device 2a control signal superimposing means 2b camera switching unit 2c camera operating unit 2d control signal generating means 3 control signal masking circuit 4 sync separation & PLL unit 4a sync separation means 5 pedestal level extraction means 5a A / D 5b Pedestal extractor 5d Burst signal extractor 5e Extracted signal generator 5e1 Zero cross detector 5e2 Detector 5e3 Waveform shaping unit 5e4 Sampling pulse generator 5e5 N-ary counter 5e6 N-ary setting unit 5f Extraction function memory 6 Mask signal generation Means 6a Additional pedestal operation unit 6b Operation function memory 6c Mask timing generation unit 7 Mask signal superimposition unit 7a Mask signal superimposition unit 7b D / A 8 Pseudo synchronization signal generation unit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 7/087 7/088 9/455 F-term (Reference) 5C022 AA00 AB64 AB65 AB68 AC01 AC27 AC69 5C054 AA02 CC02 EA01 EA03 EB01 EJ02 FF01 FF02 HA18 5C063 AA01 AB01 AC01 AC05 CA09 CA14 CA23 CA36 DA11 DA20 DB02 5C066 AA01 AA11 BA01 CA27 DC07 DC08 EG03 GA12 GA16 GA20 GA23 GB08 HA01 HA02 HA03 JA01 KD06 KE07 KE16 KE19 KE24

Claims (26)

[Claims] 1. A vertical blanking period (hereinafter, referred to as VBL)
The camera number of the surveillance camera, a color video signal with a control signal superimposed with a control signal such as control data of the camera is input, and the control signal superimposed on the VBL of the color video signal is replaced with a pedestal level. A method of masking a control signal to be output in place of a mask signal, comprising: converting an input color video signal into a digital image signal; and extracting a burst level from the digital image signal in a horizontal period in which the control signal is superimposed. Level extracting means, and a sampling clock signal (hereinafter CLK) which is phase-locked to a vertical synchronizing signal (hereinafter referred to as VD), a horizontal synchronizing signal (hereinafter referred to as HD), and a color burst signal (hereinafter referred to as burst) from the color video signal. And the pedestal level extracting means. And a mask signal superimposing means for superimposing the mask signal on the digital image signal in place of the control signal part of the digital image signal. Using a control signal mask circuit to perform, the pedestal level extraction means converts the color video signal into a digital image signal, based on the extraction signal from the extraction signal generation means, during the horizontal period in which the control signal is superimposed After extracting a burst level, the mask signal generating means calculates and outputs a reference pedestal level based on the extracted burst level based on a calculation function previously registered in a calculation function memory,
The mask signal of the reference pedestal level is generated and output. The mask signal superimposing means switches and superimposes the control signal portion of the digital image signal on the mask signal, and converts the digital image signal on which the mask signal is superimposed by switching into an analog image. A control signal masking method, which converts and outputs a signal. 2. The control signal masking method according to claim 1, wherein said extraction signal generation means generates an extraction signal for extracting a burst level at a zero cross point of said burst. 3. The control signal masking method according to claim 1, wherein said extraction signal generation means is provided with said burst detection means, and generates an extraction signal for extracting a burst level in an entire burst period. 4. The control signal masking method according to claim 1, wherein a specific zero-crossing point level calculation function that sets a burst level at a specific zero-crossing point as a reference pedestal level is registered and stored in the mask signal generating means. 5. The control signal according to claim 1, wherein the mask signal generating means registers and stores an average zero-crossing point level calculation function using an average value of burst levels at all zero-crossing points as a reference pedestal level. Mask method. 6. The control signal mask according to claim 1, wherein an average burst level operation function that sets an average value of burst levels in all burst periods as a reference pedestal level is registered and stored in said mask signal generating means. Method. 7. The control signal mask according to claim 1, wherein a specific burst level operation function that sets an average value of burst levels during a specific burst period as a reference pedestal level is registered and stored in said mask signal generation means. Method. 8. The method according to claim 8, wherein the mask signal generating means includes
2. A first burst level calculation function for registering and storing an average value of burst levels in the horizontal period in which the first control signal is superimposed as a reference pedestal level in the entire control signal superimposition period. Control signal masking method. 9. A maximum and minimum burst level operation function, wherein an average value is obtained from a maximum value and a minimum value of burst levels during the entire burst period and is used as a reference pedestal level, is stored in the mask signal generation means. Item 2. The control signal masking method according to Item 1. 10. A color video signal with a control signal in which a control signal such as a camera number of a surveillance camera and control data of the camera is superimposed on VBL, and the VBL of the color video signal is input.
In a method of masking a control signal, which is output by replacing the control signal superimposed on BL with a mask signal at a pedestal level, the input color video signal is converted into a digital image signal, and the control signal is superimposed. Pedestal level extraction means for extracting a burst level from the digital image signal during the horizontal period using a shift register means, and synchronization separation means for separating and generating VD, HD, and CLK phase-locked to the burst from the color video signal When,
A control comprising mask signal generating means for generating the mask signal based on the extracted burst level, and mask signal superimposing means for superimposing the mask signal on the digital image signal in place of the digital control signal. Using a signal mask circuit, the pedestal level extracting means converts the color video signal into a digital image signal, and converts the digital image signal into a burst in a horizontal period in which the control signal is superimposed by using the shift register means. After extracting a level, the mask signal generating means calculates and outputs the burst level extracted by the pedestal level extracting means to a reference pedestal level based on an arithmetic function set by an extracting function setting means, A pedestal level mask signal is generated and output, and the mask signal superimposing means is Aforementioned switching superimposes the control signal portion of the digital image signal to the mask signal, the control signal mask wherein the mask signal is converted outputs digital image signals switched superimposed on an analog video signal. 11. The control signal masking method according to claim 10, wherein said extraction function setting means sets an average burst level operation function that sets an average value of burst levels for all burst periods as a reference pedestal level. . 12. The control signal according to claim 10, wherein said extraction function setting means sets an all zero-cross point burst level calculation function that sets an average value of burst levels at all zero-cross points as a reference pedestal level. Mask method. 13. A peak burst level calculation function that sets an average value of burst levels at 90 ° and 270 ° points of a burst phase as a reference pedestal level. 3. The control signal masking method according to 1. 14. A color video signal with a control signal in which a control signal such as a camera number of a monitoring camera and control data of the camera is superimposed on VBL, and the V
A control signal mask circuit that replaces the control signal superimposed on BL with a mask signal of a pedestal level and outputs the separated signal, wherein VD, HD, and CLK phase-locked to a burst are separated and generated from the color video signal. Synchronous separation / P
An LL unit, an A / D (Analog Digital converter) for converting the input color video signal into a digital image signal, a burst signal extraction unit for extracting a burst from the color video signal, and an extraction function for the burst level extraction Extraction function memory that stores and stores the extracted burst, V
Extraction signal generation means for generating a burst level extraction signal from D, HD, and CLK based on the extraction function;
Pedestal level extraction means having a pedestal extraction section for extracting the burst level from the digital image signal using the burst level extraction signal; and a mask timing generation section for generating the timing of the mask signal from VD, HD, etc. And an operation function memory for registering and storing the operation function of the burst level. After calculating the burst level and calculating and outputting the reference pedestal level based on the operation function, generating a mask signal of the reference pedestal level. A mask signal generating means having an additional pedestal operation unit, a control signal unit is deleted from the digital image signal, and a mask signal superimposing unit for replacing and superposing the mask signal is provided. D / A (Digital Analog convert)
er) and a mask signal superimposing means comprising: 15. An extraction signal generating unit, comprising: a zero-cross detection unit that detects a zero-cross point pulse of a burst from a burst extracted by the burst signal extraction unit; and an extraction function registered and stored in the extraction function memory. 15. The control signal masking circuit according to claim 14, wherein the control signal masking circuit comprises a sampling pulse generation unit that generates the burst level extraction signal from the zero cross point pulse, VD, HD, or the like. 16. A detection unit for linearly detecting a burst extracted by the burst signal extraction unit, and a waveform for slicing the linearly detected waveform at a predetermined level to form a burst period signal. It is characterized by comprising a shaping section and a sampling pulse generating section for generating the burst level extraction signal from the burst period signal, VD, HD, etc. using an extraction function registered and stored in the extraction function memory. The control signal mask circuit according to claim 14, wherein 17. An N-ary counter for counting the N-ary (N = 0, 1, 2,...) After shaping the burst extracted by the burst signal extractor into a rectangular wave pulse, 15. The control signal masking circuit according to claim 14, comprising an N-ary setting unit for setting the N-ary of the N-ary counter. 18. A zero-cross point extraction function for extracting a digital image signal at a zero-cross point of a burst is stored and registered in the extraction function memory.
3. The control signal mask circuit according to 1. 19. The control signal masking circuit according to claim 14, wherein an entire burst extraction function for extracting a digital image signal for all burst periods is stored and registered in the extraction function memory. 20. The control signal mask circuit according to claim 14, wherein a specific burst extraction function for extracting a digital image signal of a specific burst period is stored and registered in the extraction function memory. 21. The control signal masking circuit according to claim 14, wherein a stable period burst extraction function for extracting a digital image signal for only a stable period of burst amplitude is registered in said extraction function memory. 22. The first horizontal period burst extraction function for extracting a digital image signal only in a horizontal period in which a first control signal is superimposed on the VBL is registered in the extraction function memory. 3. The control signal mask circuit according to 1. 23. A color video signal with a control signal in which a control signal such as a camera number of a monitoring camera and control data of the camera is superimposed on the VBL, and a V of the color video signal
A control signal mask circuit that replaces the control signal superimposed on BL with a mask signal of a pedestal level and outputs the separated signal, wherein VD, HD, and CLK phase-locked to a burst are separated and generated from the color video signal. Synchronous separation / P
An LL unit, an A / D that converts the input color video signal into a digital image signal, a burst signal extraction unit that extracts a burst from the color video signal, and an AND gate that outputs CLK only during a burst signal period; An arbitrarily settable N-ary counter that counts the CLK output from the AND gate; and a shift that shifts the digital image signal by CLK and outputs a digital image signal at burst phase points of 0, 90, 180, and 270 degrees. Pedestal level extraction means having a register, an addition operation unit for performing an addition operation on the digital image signal output from the shift register based on the setting output of the N-ary counter, and generating the timing of the mask signal from VD, HD, etc. And a digital image signal output from the addition operation unit After performing a division operation on a reference pedestal level using a predetermined extraction function, a division operation unit for generating a mask signal of the reference pedestal level, and an extraction function setting for setting extraction functions such as the N-ary counter and the division operation unit And a mask signal generating unit having a unit, a control signal unit is deleted from the digital image signal, and a mask signal superimposing unit that replaces and superimposes the mask signal is provided. And a mask signal superimposing means having a D / A for conversion and output. 24. The control signal according to claim 23, wherein the extraction function setting unit sets an average burst level extraction function in which N is an average value of burst levels in all burst periods as a reference pedestal level. Mask circuit. 25. The control according to claim 23, wherein the extraction function setting section sets a zero-cross point burst level extraction function in which N is an average value of burst levels at the zero-cross point as a reference pedestal level. Signal mask circuit. 26. The extraction function setting unit sets a peak burst level extraction function in which N is an average value of burst levels at 90 degrees and 270 degrees of a burst phase as a reference pedestal level. Item 24. The control signal mask circuit according to item 23.