JP4490805B2 - Color television camera device - Google Patents

Description

  The present invention relates to a television camera apparatus having an external synchronization function, and more particularly to a color television camera apparatus having an external synchronization function for synchronizing a subcarrier of its own device.

  For example, in broadcasting stations, multiple color television cameras are often combined and operated as a system, but at this time, it is necessary to prevent synchronization disturbance between color television camera devices. A color television camera device provided has been conventionally proposed (see, for example, Patent Document 1).

  The external synchronization function is a function for synchronizing the video signal of the own camera device with the video signal input from the outside. The own camera device at this time is a plurality of color television cameras. This is a camera device that is going to be externally synchronized.

  For this external synchronization function, a PLL (Phase Locked Loop) circuit is usually used. The PLL circuit is operated by using a horizontal synchronization signal included in a video signal input from the outside as a reference input. In general, the clock output from the clock oscillation circuit of the camera apparatus is synchronized.

  More specifically, there are a luminance system method and a chroma system method as follows. First, in the luminance system method, a horizontal synchronization signal is extracted from the luminance signal of an externally input video signal, and the phase of the horizontal synchronization signal is generated from a clock that is a reference of the luminance signal of the own camera device. Another color television camera that is input from the outside by configuring a PLL circuit that controls the oscillation frequency of the oscillation circuit that generates the clock based on the comparison result and the phase of the horizontal synchronization signal The luminance signal of the own camera device is synchronized with the luminance signal included in the video signal.

Next, in the method based on the chroma system, a burst signal is extracted from the chroma signal included in the video signal, and the phase of the burst signal is generated based on a clock that is a reference of the chroma signal of the own camera device. Another color television input from the outside by configuring a PLL circuit that compares the phase of the carrier signal (burst signal) and controls the oscillation frequency of the oscillation circuit that generates the clock based on the comparison result The chroma signal of the own camera device can be synchronized with the chroma signal included in the video signal of the camera.

  In this way, by simultaneously operating two systems of the PLL of the luminance system and the chroma system, the luminance signal and the chroma signal are both included in the video signal input from the outside and the video signal synchronized with the chroma signal. Can be output.

  Here, an example of a circuit relating to external synchronization in a conventional color television camera apparatus will be described with reference to FIG. 5. First, an external synchronization input signal (GenLock signal: GL signal) supplied from the outside is supplied from the input terminal 21. Input to the synchronization signal separation IC 22. The burst signal is extracted here and supplied to the external synchronization function IC 23. Here, the external synchronization function IC is generally called a GenLock IC, and is provided with an adjustment signal input and connected to the control signal input terminal 27.

  On the other hand, in the voltage controlled oscillator 25, a clock serving as a reference for the chroma signal is generated, and this clock is frequency-divided by the 1 / N frequency divider 26 and used in the own camera device SC (subcarrier). A signal, that is, an own device SC signal is supplied to the external synchronization function IC 23.

Therefore, the external synchronization function IC 23 compares the phase of its own SC signal with the phase of the burst signal and supplies the comparison result to an LPF ( low-pass filter) 24. The comparison result filtered here is fed back to a VCO (voltage controlled oscillation unit) 25 as a control voltage. As a result, the oscillation frequency of the VCO 25 is controlled by an external synchronization input signal, and the camera apparatus is synchronized. Will be given.

Therefore, in this case, the loop system including the external synchronization function IC 23, the LPF 24, the VCO 25, and the 1 / N frequency divider 26 constitutes a so-called PLL, which is a burst extracted from the external synchronization input signal. By operating the signal as a reference input, the external SC signal that is externally synchronized is obtained at the output terminal 28.

  The above prior art does not take into consideration the need for a synchronization signal separation IC and an external synchronization function IC, and there is a problem in miniaturization of the color television camera device.

As described above, in the prior art, the synchronization signal separation IC and has an external synchronization function IC is used, they often are provided as dedicated IC, therefore, the size reduction for the package size is large toward No. On the other hand, it is difficult to obtain ICs that have the same functions as those of these dedicated ICs and can be replaced with them. Therefore, the conventional technology causes a problem in miniaturization of the color television camera apparatus.

  Further, in the phase correction of the subcarrier system, the phase is often confirmed by a vector display. For this reason, in the above-described prior art, the 360-degree phase is divided into four, and each of the 90-degree divided ranges is analog. In this case, it is difficult to accurately realize the 90 degree division range, and in order to secure the 360 degree correction range, it is necessary to secure a correction amount of 90 degrees or more for each divided region. As a result, there is a case where the correction process crosses the dividing points, and in this case, there is a problem that discontinuous points are generated.

  Also in color television camera devices, in recent years, digitization has progressed, and there are many parts that use digital circuits such as image quality improvement systems and timing generation systems. There was no consideration.

  An object of the present invention is to provide a color television camera apparatus having an external synchronization function by digital processing.

The object is to extract a burst signal component from the external synchronization input signal as a digital signal in a color television camera apparatus provided with an external synchronization function for synchronizing the own subcarrier signal to the external synchronization input signal. And the phase difference between the burst signal component converted into the digital signal and the own subcarrier signal is converted into an angle obtained by adding the phase angle in the zone to the phase angle of the zone obtained by dividing 360 degrees into eight quadrants. Means for controlling the phase of the own subcarrier signal based on the converted angle .

According to the above means, the video signal input from the outside is digitized, the phase difference is detected by signal processing from the digitized external synchronization signal, correction data is created, and the chroma signal of the own camera device is filtered and processed. The oscillation frequency of the oscillation circuit that generates the reference clock is controlled, the burst signal component is extracted from the external synchronization signal, the phase is compared with the subcarrier signal of the own camera device, and the processing until the correction data is created is digital As a result, it is possible to realize a color television camera device capable of continuously performing 360 ° phase correction.

  According to the present invention, the phase difference between the burst signal component of the external synchronization input signal and the sub-carrier signal of the own camera device is calculated by digital signal processing, and correction data is created from the phase difference. Can be continuously varied over 360 degrees, and the stability of operation against temperature fluctuations can be improved.

  Hereinafter, a color television camera apparatus according to the present invention will be described in detail with reference to embodiments shown in the drawings.

  FIG. 1 shows, as an example, an embodiment in which the present invention is applied to an NTSC color television camera apparatus. In this case as well, the external synchronization input signal is input from the input terminal 1 to the external synchronization unit. In this embodiment, first, it is converted into a digital signal by an A / D (analog-digital converter) 2. The digitized external synchronization input signal is filtered by a BPF (band-pass filter) 3, whereby only the chroma signal component is extracted and supplied to the burst extraction unit 4.

  The burst extraction unit 4 extracts only the burst signal component from the chroma signal component of the input external synchronization input signal and supplies it to the phase difference determination unit 5, and the phase difference determination unit 5 extracts data from this burst signal component. X and zone Z are calculated digitally and supplied to the phase difference converter 6. The data X and the zone Z will be described in detail later.

At this time, the control signal for adjustment is input from the input terminal 10 to the phase difference conversion unit 6 and given a predetermined phase difference correction angle required for adjustment and the like. Therefore, the phase difference conversion unit 6 calculates the phase angle of the burst signal component of the external synchronization input signal based on the data X and the zone Z input from the phase difference determination unit 5, and uses this as the phase difference correction angle for adjustment. Are mixed with each other, the phase is compared with the own SC signal, the phase error is output as correction data H, and it is supplied to the LPF 7.

  Therefore, the LPF 7 filters the input correction data H and supplies it to the VCO 8 as a control voltage. As a result, the oscillation frequency of the VCO 8 is controlled by the correction data H and becomes a frequency synchronized with the external synchronization input. Therefore, the output of the VCO 8 is N-divided by the 1 / N divider 9 to generate its own SC signal. At this time, if the oscillation frequency of the VCO 8 is, for example, four times the frequency of the required subcarrier signal, the 1 / N divider 9 may divide by 4, that is, the division ratio N = 4. .

  Thus, the own SC signal output from the 1 / N frequency dividing unit 9 is supplied to the phase difference converting unit 6, whereby the LPF 7, VCO 8, and 1 / N frequency dividing unit 9 are supplied from the phase difference converting unit 6. A loop returning to the phase difference conversion unit 6 is formed via these, and a PLL is constituted by these portions.

  As a result, the own SC signal synchronized with the external synchronization input signal can be obtained at the output terminal 11. Therefore, it is possible to provide a color television camera apparatus having an external synchronization function according to this embodiment. Here, the present embodiment is characterized in that the phase difference determination unit 5 is digitized. Next, details of the phase difference determination unit 5 will be described.

  FIG. 2 shows an example of the digitized phase difference determination unit 5 in this embodiment. In this example, the self-system SC signal is used as it is for the operation clock, or is formed into a waveform suitable for the clock. The burst signal component extracted from the chroma signal by the burst extraction unit 4 is input to the input terminal 50.

  At this time, the SCDEC (subcarrier decoder) 51 inputs the own SC signal as a clock and functions to sequentially generate signals EN1, EN2, EN3, and EN4 for each clock. That is, from the SCDEC 51, the signals EN1, EN2, EN3, and EN4 are generated in a cycle with four clocks.

  Here, it is assumed that the period for external synchronization is set to the period from the signal EN1 to the signal EN2. Then, in this case, the signals EN1 and EN2 are supplied to FF (flip-flop) 1 and FF2, and the signals of the digital external synchronization input signal supplied to the input terminal 50 using these signals EN1 and EN2 as enable signals. So that adjacent 2-bit data is evaluated every 4 clocks. Therefore, at this time, the signals EN3 and EN4 remain unused.

  Then, the data latched by these FF1 and FF2 are respectively subjected to AVE (averaging) processing to average value data B and D as shown in the figure, and further, these data are subjected to ABS (absolute value) processing to obtain absolute values. Value data A and C.

  Then, from the relationship between the average value data and the absolute value data in these burst periods, as shown in FIG. 3, the phase of the burst signal included in the external synchronization input signal is divided into 360 quadrants into 8 quadrants. It is possible to identify which zone is in the zone.

  In FIG. 3, first, (a) represents the determination condition of the zone Z based on the average value data B, D and the absolute value data A, C, and (b) represents the determination result of the zone Z.

  Therefore, these data A to D are input to the ZONE (zone) determination unit 52, where calculation processing according to the determination conditions shown in FIG. 3A is executed, as shown in FIG. Then, the zone Z is determined and output to the output terminal 53.

  At this time, the external synchronization input signal supplied to the input terminal 50 is also input to the magnitude comparison unit 53 after being subjected to band-pass filter processing. At this time, on the one hand, it is input to the size comparison unit 53 as it is, and on the other hand, it is input after being latched by FF for one clock.

  As a result, the size comparison unit 53 sequentially compares the data of two adjacent points in the burst signal for each bit, and outputs the adjacent data divided into a larger one and a smaller one. Then, these are subjected to AVE (averaging) processing, and BDATA, which is an average value of large data, and SDATA, which is an average value of small data, are calculated.

  These data BDATA and SDATA are subjected to ABS (absolute value) processing as shown in the figure and input to the divider 55, where data X is generated by the following division processing.

X = | SDATA | / | BDATA |
◆
Here, it is assumed that the burst signal component of the color television signal is sampled with a subcarrier clock having a frequency four times that of the subcarrier. Then, the burst signal component is expressed by a trigonometric sin function, and the phase of the burst signal is θ, and sinθ, sin (θ + Π / 2) = cosθ, sin (θ + Π) = − sinθ, sin (θ + 3 * Π / 2) = −cos θ, and in this case, the previously obtained data X corresponds to tan θ. Here, Π represents the circumference ratio (: π≈3.14159...).

  At this time, since the absolute value processing is performed as described above, the range of the angle θ is limited to within 45 °, that is, 0 ° ≦ θ ≦ 45 °. If the angle θ is within 45 °, the angle and the trigonometric function have a one-to-one correspondence. Therefore, the arctan function can be easily obtained from the data X only by using the table ROM, and the angle θ can be obtained.

In addition, at this time, as shown in FIG. 3B, the zone in which the phase of the burst signal included in the external synchronization input signal is located is detected in parallel by the ZONE determination unit 52, and the zone Z Therefore, the actual phase angle θ ^* of the burst signal is an angle obtained by adding the phase angle in each zone to the angle θ given by the data X.

For example, when the zone is Z1, since the zone Z1 starts from 0 °, the phase angle θ ^* = θ + (45 ° × 0) = θ, and when the zone is Z2, the zone starts from 45 °. The phase angle θ ^* = θ + (45 ° × 1) = θ + 45 °. Similarly, in the zone Z3, the phase angle θ ^* = θ + (45 ° × 2) = θ + 90 °, and in the zone Z4, the phase angle θ ^*. = Θ + (45 ° × 3) = θ + 135 ° …… In zone Z8, the phase angle θ ^* = θ + (45 ° × 7) = θ + 315 °, and since the angle θ is within 45 °, it is continuous from 0 ° to 360 °. Thus, the phase angle θ ^* can be obtained.

  Therefore, the data X and the zone Z are input to the phase difference conversion unit 6, and the phase of the burst signal component of the external synchronization input signal is combined by combining the data X and the zone Z, and the correction by the control signal is added to this. If the correction data H is used and compared with the phase of the own device SC signal, the oscillation frequency of the voltage controlled oscillator 8 is controlled by the external synchronization input signal, and external synchronization of the own camera device is given.

FIG. 4 shows details of the phase difference conversion unit 6. In this example, the phase difference conversion unit 6 is constituted by a conversion circuit 60 and a correction circuit 61, and data X and zone Z are input to the conversion circuit 60. As described above, the phase angle θ ^* is generated from the data X and the zone Z and is input to the correction circuit 61. Then, in the correction circuit 61, the phase angle θ ^* is added with the correction amount by the control signal, the phase is compared with the own SC signal, and the control voltage of the voltage controlled oscillation unit 8 is obtained.

  Therefore, according to this embodiment, functions equivalent to the synchronization signal separation IC and the external synchronization function IC in the prior art can be obtained by digital processing, and as a result, it greatly contributes to miniaturization of the color television camera device. be able to.

  Further, according to this embodiment, since the digital processing is performed, the zone division can be accurately obtained, and as a result, there is no possibility of discontinuity, and phase synchronization can be obtained continuously over 360 °. .

  By the way, in the color television signal, when 4 clocks are set as 1 cycle, there are about 10 burst components, but at this time, the burst signal is usually subjected to a slope process.

  However, in the above embodiment, since band-pass processing is applied to the burst signal in the previous stage, it is limited to use only the central part of the burst component that exists for about 10 cycles, and thus the accuracy of the detection data is improved. In addition, the accuracy of the correction data is improved.

  Here, in the above-described embodiment, the example in which the oscillation frequency of the NTSC subcarrier system clock is multiplied by 4 has been shown. However, the present invention is not limited to the multiplication by 4 but may be a multiple of 4. The same can be done with N-multiplied ones.

  In the embodiment described above, the case of the NTSC system has been described. However, the present invention relates to the relationship between the vertical synchronization component and the burst signal component of the external synchronization input signal even when the color television camera apparatus is the PAL system, for example. Can be easily applied by generating a LINE switching signal peculiar to the PAL system, shifting the comparison position for each LINE, or performing a process such as thinning out the comparison process every two lines (LINE).

It is a block diagram of the external synchronization processing part in one Embodiment of the color television camera apparatus by this invention. It is a block diagram which shows an example of the phase difference determination part in one Embodiment of this invention. It is explanatory drawing of operation | movement of the phase difference determination part in one Embodiment of this invention. It is a block diagram which shows an example of the phase difference conversion part in one Embodiment of this invention. It is a block diagram which shows an example of the external synchronization process part in the color television camera apparatus by a prior art.

Explanation of symbols

1: External sync signal input terminal 2: A / D (analog-digital converter)
3: BPF (band-pass filter)
4: Burst extraction unit 5: Phase difference determination unit 6: Phase difference conversion unit 7: LPF (low-pass filter)
8: Voltage control oscillation unit 9: 1 / N frequency division unit 10: Control signal input terminal 11: Output terminal (output terminal of own subcarrier)

Claims (1)

In a color television camera device provided with an external synchronization function for synchronizing its own subcarrier signal with an external synchronization input signal,
Means for extracting a burst signal component from the external synchronization input signal as a digital signal;
Means for converting a phase difference between the burst signal component converted into the digital signal and the own subcarrier signal into an angle obtained by adding a phase angle in the zone to a phase angle in a zone obtained by dividing 360 degrees into eight quadrants; Provided,
A color television camera apparatus, wherein the phase of the own subcarrier signal is controlled based on the converted angle .

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