JP3506589B2 - Surveillance camera system and signal correction method for camera system - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera system in which a system control section including a signal processing circuit and a small camera head section are separated from each other.
The present invention relates to a surveillance camera system for correcting distortion of a signal transmitted from a camera head unit to a signal processing circuit, and a signal correction method in the surveillance camera system.

[0002]

2. Description of the Related Art Today, two-dimensional solid-state image pickup devices (hereinafter simply referred to as C
A television camera using a CD is often used.
As the surveillance camera system, as shown in FIG. 2, the oscillation circuit 15, the CCD 19 and the CCD drive control circuit 17 are incorporated in the camera head unit 11, and the CCD output signal from the camera head unit 11 is sent to the system control unit 31. Some processing circuits 37 perform conversion processing into video signals.

As described above, the surveillance camera system in which the signal processing circuit 37 for converting the CCD output signal into the video signal is separated from the camera head portion 11 can be downsized and is suitable for the surveillance camera. It is a thing.
Further, the oscillator circuit 15 of the camera head unit 11 is a phase-locked oscillator circuit 15, the reference clock generation circuit 33 is provided in the system control unit 31, and the phase is synchronized with the reference clock signal output from the reference clock generation circuit 33. The generated clock pulse may be formed by the oscillator circuit 15.

As described above, when the phases of the clock pulses formed and used by the camera head unit 11 are matched with the reference clock signal of the system control unit 31, a plurality of camera head units are provided.
The timings of the CCD output signals formed by 11 can be matched, and a surveillance camera system having a large number of camera heads 11 can be easily formed. In such a surveillance camera system, when the camera head unit 11 and the system control unit 31 are connected by a single coaxial cable, the camera head unit 11 is provided with a phase-locked oscillator circuit 15 such as a PLL circuit or a pulse separation circuit. 13, a CCD 19 and a CCD drive control circuit 17 are provided, and the system control unit 31 is provided with a reference clock generation circuit 33, a reference signal forming circuit 35, and a signal processing circuit 37.

The reference clock generation circuit 33 of the system control unit 31 forms a reference clock signal necessary for driving the CCD 19 and the signal processing circuit 37, and the reference signal formation circuit 35 uses this reference clock signal as a reference synchronization signal. System control unit
It is output to the video signal line 29 that connects the camera head unit 11 and the camera head unit 11. As shown in FIG. 3, this reference synchronization signal is output during the blanking period H0 in synchronization with the timing of the blanking period H0 in the video signal, and is formed with the required number of reference clock signals. It is something. Then, this reference synchronization signal is sent to the camera head unit 11 via a video signal line 29 which is a coaxial cable as a signal forming a synchronization signal such as a vertical and horizontal synchronization signal.

In the camera head section 11, the pulse separation circuit 13 extracts the pulse of the reference synchronizing signal from the video signal line 29, sends the pulse of the reference clock signal to the oscillation circuit 15, and determines the number of pulses of the reference clock signal. The vertical and horizontal synchronizing signals are formed by the above and are sent to the CCD drive control circuit 17. Therefore, the phase of the clock pulse formed by the oscillator circuit 15 can be matched with the phase of the reference clock signal, and the timing of one frame when driving the CCD 19 is also the reference synchronization formed by the reference signal forming circuit 35 of the system control unit 31. It can be controlled by a signal.

Further, the CCD drive control circuit 17 includes an oscillation circuit 15
Is output to the CCD 19 as a horizontal transfer pulse which is a CCD drive pulse. When outputting the horizontal transfer pulse, the output of the horizontal transfer pulse is stopped during the blanking period H0 based on the synchronizing signal from the pulse separation circuit 13, and the vertical transfer pulse is appropriately output to output the accumulated charge. The lines are sequentially changed so that the CCD 19 outputs a CCD output signal as image information for one screen.

Then, the accumulated charge from the final line is CC
After the output as the D output signal, the output of the accumulated charge is stopped for the time of the vertical blanking period, and then the accumulated charge is sequentially output again from the first line. Further, the CCD drive control circuit 17 outputs the accumulated charge output from the CCD 19 to the video signal line 29 as a CCD output signal which is appropriately amplified, and the CCD output signal is output to the system control unit 31.
To send to.

Further, the signal processing circuit 37 of the system control unit 31 removes the reference synchronizing signal from the signal of the video signal line 29, and based on the CCD output signal which is a video signal component, a luminance signal and a color difference signal of NTSC standard, etc. Or a composite video signal or the like is further formed from the luminance signal and the color difference signal and is output from the output terminal 39. In the camera system that forms this color video signal, the CCD 19
As such, the CCD 19 using the complementary color filters of cyan, magenta, yellow and green may be used.

As an example of this complementary color filter, as shown in FIG. 4, there is one in which rows of cyan (C) and magenta (M) and rows of yellow (Y) and green (G) are alternately formed. Then, the CCD 19 outputs the charges generated in the pixels forming the respective filters as accumulated charges in accordance with the horizontal transfer pulse φ. Further, in outputting each of the accumulated charges, as shown in A of FIG. 5, after the accumulated charges of the cyan (C) and magenta (M) pixels are output, the yellow (Y) and The accumulated charge of the green (G) pixel is output, and the accumulated charge of the adjacent four primary color pixels forms the image information of one pixel.

As the CCD output signal, when the accumulated charges of the four primary color pixels are output, as shown in FIG. 5B, the average of the accumulated charges of the two primary color pixels of cyan (C) and magenta (M). The value and the average value of the accumulated charges of the two primary color pixels of yellow (Y) and green (G) are used as the values of the luminance information, and cyan (C), magenta (M), yellow (Y), and green (G). The CCD output signal is formed by using the value of the accumulated charge of each primary color pixel of FIG.

Although there are various types of complementary color filter arrangements, most of them use the average value of the accumulated charge for each of the adjacent two primary color pixels as the luminance information. And
In the signal processing circuit 37, based on this luminance information, the NTSC
A luminance signal of a standard or the like is formed, and a color difference signal is formed based on the color information of the four primary color pixels.

[0013]

In the surveillance camera system today, the distance between the camera head section for outputting a CCD output signal and the system control section for converting the CCD output signal into a video signal of NTSC standard or PAL standard is long. Becomes
The CCD output signal input to the signal processing circuit of the system controller may be weak.

Then, the CCD output signal is amplified by using an automatic amplification factor adjusting amplifier circuit (auto gain control circuit) or the like, and a video signal is formed based on the amplified CCD output signal. However, when a weak CCD output signal is amplified to form a color video signal, the color of an image may be unnatural.

The present invention eliminates such drawbacks and allows the camera head section to the system control section through the video signal line to the C line.
It is an object of the present invention to provide a surveillance camera system that corrects the distortion generated when transmitting a CD output signal and forms a video signal with excellent color reproducibility.

[0016]

The present invention provides an oscillator circuit and a C
In a surveillance camera system in which a camera head unit including a CD drive control circuit and a CCD and a system control unit including a signal processing circuit for converting a CCD output signal into a video signal are connected by a relatively long video signal line, a CCD
A pulse detection circuit for providing a detection pulse generation circuit for inserting a detection pulse having a constant peak value having a frequency equal to the frequency of the drive pulse in the blanking period of the CCD output signal in the camera head section and separating the detection pulse from the CCD output signal, And a system of amplification factor control means for detecting the peak value of the detection pulse separated by the pulse detection circuit to control the amplification factor of the CCD output signal and also controlling the amplification factor of the luminance signal by the peak value of the detection pulse. A surveillance camera system provided in the control unit.

As described above, since the camera head unit has the detection pulse generation circuit for generating the detection pulse having the constant peak value, the detection pulse having the constant peak value can be output from the camera head unit. Further, since the system control unit has a pulse detection circuit for extracting the detection pulse and an amplification factor control means for detecting the peak value of the extracted detection pulse, the amplification factor control means provides a constant peak value. The attenuation rate of the signal transmitted from the camera head section to the system control section through the video signal line can be detected based on the peak value of the power detection pulse. That
Since the video signal line standard and length are common,
Each signal is reduced according to the ratio of the loose frequency to the frequency of each signal.
The decay rate is calculated and the control to adjust the amplification rate can be performed.
Kill Therefore, it is possible to form an excellent video signal of the color reproducibility.

[0018] Also, since you are detecting pulse generating circuit for outputting a pulse frequency equal to the frequency of the CCD driving pulse during a blanking period as a detection pulse, equal to the frequency of the color information the frequency of the detection pulses in the CCD output signal
Then, the CCD output signal is increased by amplification that restores the color information correctly.
It can also be done by adjusting the width .

By superposing this detection pulse on the CCD output signal, the signal attenuation rate detected by the amplification factor control means and the attenuation rate of the color information signal in the CCD output signal are equal, and the amplification degree of the CCD output signal is increased. It can be easily determined. Further, according to the present invention, a CCD output in which a detection pulse having a constant frequency equal to the frequency of the CCD drive pulse which always has a constant peak value is formed in the camera head portion and this detection pulse is inserted in the blanking period of the CCD output signal A signal is output from the camera head section, the peak value of this detection pulse is detected by the system control section, and based on the attenuation rate and frequency of the detection pulse, each information is matched to the frequency band of the color information and luminance information of the CCD output signal. A signal correction method for a surveillance camera system that adjusts the amplification of a signal.

As described above, since the CCD output signal is amplified for each frequency component based on the frequency and the attenuation rate of the reference detection pulse, the distortion of the CCD output signal due to the transmission via the video signal line is corrected. be able to.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a surveillance camera system according to the present invention, as shown in FIG.
The detection pulse generating circuit 21 is provided in the, the system control unit 31 is provided with the pulse detection circuit 41 and the amplification factor control means 43,
A signal amplification amplifier 45 for amplifying the CCD output signal input to the signal processing circuit 37 is provided.

Camera head section of this surveillance camera system
Reference numeral 11 denotes a pulse separation circuit 13 and a phase-locked oscillator circuit 15, and the pulse separation circuit 13 extracts a reference synchronization signal sent from a system control unit 31 via a video signal line 29,
The phase of the clock pulse output from the oscillator circuit 15 is matched with the phase of the reference clock, and the vertical synchronizing pulse and the horizontal synchronizing pulse are output to the CCD drive control circuit 17 based on the reference synchronizing signal, as in the conventional case.

Not only when the reference synchronization signal is sent to the camera head section 11 through the video signal line 29, but also when the system control section is used.
The reference clock from the reference clock generating circuit 33 of 31 and the reference synchronizing signal or the vertical / horizontal synchronizing signal formed by the reference signal forming circuit 35 may be sent to the camera head unit 11 via a control signal line different from the video signal line 29. And the camera head
The detection pulse generation circuit 21 incorporated in 11 receives the clock pulse from the oscillation circuit 15 and outputs the clock pulse to the video signal line 29 as a detection pulse having a constant peak value.

This detection pulse is supplied to the CCD drive control circuit 17
Is output to the video signal line 29 as a required number of pulses at a predetermined position during the horizontal blanking period during which no CCD output signal is output from the device. Also, the CCD of this camera head unit 11
A CCD 19 of 250,000 pixels using complementary color filters of cyan, magenta, yellow, and green is incorporated in 19 and the frequency of the clock pulse which is the CCD drive pulse is about 10 MHz.

Therefore, the frequency of the color information in the CCD output signal is about 10 MHz which is equal to the frequency of the clock pulse which is the CCD driving pulse, and the frequency of the luminance information is about 5 MHz which is half the frequency of the CCD driving pulse. Is output from the CCD drive control circuit 17 to the video signal line 29. Further, in this surveillance camera system, as described above, the detection pulse from the detection pulse generation circuit 21 is output to the video signal line 29, and the output timing of this detection pulse is synchronized with the CCD drive control circuit 17. The signal is output at a predetermined timing during the horizontal blanking period.

Therefore, the CCD output signal in which the detection pulse from the detection pulse generating circuit 21 is superimposed in the blanking period is output from the camera head unit 11. The system control unit 31 is provided with a pulse detection circuit 41 for extracting this detection pulse from the CCD output signal, and an amplification factor control means for detecting the peak value of the extracted detection pulse and controlling the amplification degree of the CCD output signal. 43 is provided with a microcomputer.

The system control unit 31 includes a CCD 19
A reference clock generation circuit 33 that generates a reference clock according to the frequency of a clock pulse that drives the reference clock and a reference signal formation circuit that forms a reference synchronization signal that indicates the timing of the synchronization signal based on the reference clock formed by the reference clock generation circuit 33. 35 and a signal processing circuit 37 for forming a video signal or the like from the CCD output signal is the same as in the conventional case, and the CCD output via the signal amplification amplifier 45 whose amplification degree is controlled by the amplification factor control means 43. The signal is input to the signal processing circuit 37.

The pulse detection circuit 41 attached to the system control section 31 receives the CCD output signal input from the camera head section 11 via the video signal line 29 and the reference synchronization signal from the reference signal forming circuit 35. And C by the reference synchronization signal
Only the detection pulse signal is extracted from the CD output signal and sent to the amplification factor control means 43. Also, amplification factor control means
43 is CC based on the peak value of the input detection pulse
When the peak value of the detection pulse input to the system control unit 31 is low, the amplification factor of the D output signal is determined and the amplification factor of the luminance signal in the video signal formed by the signal processing circuit 37 is also determined and controlled. In addition, the amplification factor of the signal amplification amplifier 45 is increased, the amplification factor corresponding to the amount of change in the peak value is controlled, and the amplification factor of the luminance signal is also reduced.

That is, the resistance attenuation constant α1 of the coaxial cable used for the video signal line 29 is

[0030]

[Equation 1] Therefore, depending on the standard of the video signal line 29 used and the frequency of the detection pulse, the attenuation rate per km [d
B] is obtained, and the peak value of the detection pulse whose output peak value is constant is used to determine the attenuation rate until transmission to the system control unit 31, and thus the cable length from the camera head unit 11 to the system control unit 31 and each It is possible to know the attenuation rate of a signal at a frequency.

Therefore, it is possible to calculate the attenuation rate until it is transmitted to the system control unit 31 by the frequency of the color information and the brightness information, and it is possible to calculate the amplification degree for restoring the color information and the brightness information to the original. In this surveillance camera system,
Since the frequency of the detection pulse is equal to the frequency of the CCD drive pulse, that is, the frequency of the color information, the amplification factor of the CCD output signal is determined by using the attenuation rate of the detection pulse as the attenuation rate of the color information.

As described above, if the amplification factor of the CCD output signal is determined based on the peak value input to the system control unit 31 by the detection pulse output from the camera head unit 11 at a constant peak value, the video signal line 29 CCD based on cable length
It is possible to correct the attenuation of the output signal. Then, the amplification factor of the CCD output signal is determined according to the attenuation rate of the detection pulse, and the color difference signals formed by the signal processing circuit 37 are accurately formed by matching the color information of the four primary colors with the values at the time of output from the CCD 19. be able to.

Since the frequency of the luminance information is one half of the frequency of the color information in the CCD output signal, the attenuation rate of the luminance information is about 0.707 times the attenuation rate of the color information. The quantity is input to the system control unit 31. Therefore, since the luminance information input to the signal processing circuit 37 is excessively amplified with respect to the output time of the CCD 19, the signal processing circuit 37 forms a luminance signal based on the luminance information and the color difference signal based on the color information. When forming, the amplification control signal for reducing the amplification factor of the luminance signal as compared with the amplification factor of the color difference signal is input to the signal processing circuit 37.

As described above, based on the peak value of the detection pulse output as a constant peak value from the camera head unit 11, the microcomputer using the amplification factor control means 43 to determine the amplification factor of the CCD output signal or the luminance signal. By controlling, the distortion of the CCD output signal in the surveillance camera system in which the cable length of the video signal line 29 is long is corrected,
A video signal with excellent color reproducibility can be formed.

In the surveillance camera system having in the system control section 31 an automatic amplification factor adjustment amplification circuit (auto gain control circuit) for greatly amplifying the CCD output signal when the visual field of the camera head section 11 becomes dark, the signal amplification The amplifier 45 is omitted, the control signal from the amplification factor control means 43 is input to the automatic amplification factor adjustment amplification circuit, and the CC depending on the cable length is used.
It is also possible to perform the level reduction of the D output signal and the brightness correction of the screen when the visual field becomes dark by the automatic amplification factor adjusting amplifier circuit.

As the detection pulse, a pulse obtained by dividing a clock pulse, which is a CCD drive pulse, by half may be used to match the frequency of the detection pulse with the frequency of the luminance information. In this case, a signal processing circuit is provided for the signal based on the color information of the CCD output signal and the signal based on the luminance information.
After the separation at 37, a signal based on color information is further amplified, and then a color difference signal is formed.

As described above, if the frequency of the detection pulse is adjusted to the frequency of the luminance information, the amplification degree before or immediately after the input to the signal processing circuit 37 is reduced to reduce the signal attenuation due to the cable length of the video signal line 29. The correction can be easily performed. Further, in controlling the amplification degree of the CCD output signal by the amplification factor control means 43, after separating the CCD output signal into a luminance signal based on luminance information and a color difference signal based on color information, the amplification degree of the color difference signal and the luminance signal are separated. The amplification degree and the amplification degree may be individually controlled.

[0038]

According to the first aspect of the present invention, the camera head portion has a detection pulse generation circuit for inserting a detection pulse having a constant peak value in the blanking period of the CCD output signal, and the detection pulse is output from the CCD output signal. The system control unit is provided with a pulse detection circuit for separation and an amplification factor control means for detecting the peak value of the separated detection pulse to control the amplification factor of the CCD output signal and also the amplification factor of the luminance signal. The surveillance camera system has.

Therefore, it is possible to perform amplification to correct the attenuation amount of the CCD output signal by the decrease of the peak value of the detection pulse output at the constant peak value, and the attenuation according to the frequency of the luminance information and the color information of the CCD output signal. Amplify to correct
Even if the video signal line between the camera head section and the system control section is long, a video signal with excellent color reproducibility can be formed.

Then, according to the present invention, a pulse having a frequency equal to the frequency of the CCD drive pulse is used as the detection pulse, and
A <br/> which the detection pulse generating circuit for outputting a CD output signal. Therefore, the amount of attenuation of the detection pulse is equal to the amount of attenuation of the color signal in the CCD output signal, and it becomes easy to determine the amplification degree for correcting the attenuation. It is also easy to form the detection pulse using the CCD drive pulse.

The invention according to claim 2 forms a detection pulse of a constant frequency having a constant peak value at the camera head section, and inserts this detection pulse into the blanking period of the CCD output signal. A signal is output from the camera head section, the peak value of this detection pulse is detected by the system control section, and based on the attenuation rate and frequency of the detection pulse, each information is matched to the frequency band of the color information and luminance information of the CCD output signal. A signal correction method for a surveillance camera system that adjusts the amplification of a signal.

Therefore, it is possible to calculate the amplification for correcting the attenuation amount in each frequency band of the CCD output signal by the decrease of the peak value of the detection pulse which is output at the constant peak value with the constant frequency. Amplification is performed to correct the attenuation according to the frequency of the luminance information and color information of
Even if the video signal line between the camera head section and the system control section is long, a video signal with excellent color reproducibility can be formed.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of a surveillance camera system according to the present invention.

FIG. 2 is a block diagram showing an example of a conventional surveillance camera system.

FIG. 3 is a diagram showing an example of a reference signal in the surveillance camera system.

FIG. 4 is a diagram showing an arrangement example of complementary color filters of a CCD in a color CCD camera.

FIG. 5 is a diagram showing an example of a CCD output signal in a color CCD camera.

[Explanation of symbols]

11 camera head section 13 pulse separation circuit 15 oscillation circuit 17 CCD drive control circuit 19 CCD 21 detection pulse generation circuit 29 video signal line 31 system control section 33 reference clock generation circuit 35 reference signal formation circuit 37 signal processing circuit 39 output terminal 41 pulse Detection circuit 43 Amplification factor control means 45 Signal amplification amplifier

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H04N 7/18 H04N 5/225

Claims (2)

(57) [Claims] 1. An oscillator circuit, a CCD drive control circuit, and a CC
In a surveillance camera system in which a camera head section that incorporates D and a system control section that incorporates a signal processing circuit that converts the CCD output signal into a video signal are connected by a video signal line , a CCD drive pulse with a constant peak value Equal to the frequency of
The camera head has a detection pulse generation circuit that outputs a pulse of a high frequency to the video signal line as a detection pulse to be inserted in the blanking period of the CCD output signal. The system control unit has a pulse detection circuit and an amplification factor. Control means
And the pulse detection circuit separates the detection pulse from the CCD output signal , and the amplification factor control means detects the peak value of the detection pulse separated by the pulse detection circuit to detect the system control from the camera head section.
To calculate the attenuation rate until the signal is transmitted to the control unit
Controlling the amplification degree of the input CCD output signal more to the system control unit, and the attenuation factor of the signal at each frequency the
Calculated by the ratio of the frequency of the signal and the frequency of the detection pulse
The surveillance camera system is characterized in that the amplification degree of the luminance signal is also controlled based on the attenuation rate . 2. A CCD drive pattern which always has a constant peak value.
The detection pulse of the constant frequency equal to the frequency of the lu
It is formed by the head part, and this detection pulse is used for the CCD output signal.
Output to the video signal line so that it can be inserted during the blanking period
Output the CCD output signal with the superimposed noise from the camera head.
The peak value of this detection pulse in the system controller.
CC based on the attenuation rate and frequency of the detected pulse
Each according to the frequency band of the color information and brightness information of the D output signal
A signal correction method for a surveillance camera system , which comprises adjusting the amplification of an information signal .