JP3029675B2 - NTSC video camera with PAL signal output - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an NTSC video camera, and more particularly to an NTSC video camera capable of switching to a PAL signal output.

[0002]

2. Description of the Related Art The number of scanning lines per frame is 525 lines / 60 Hz in the NTSC system, but 625 lines in the PAL system.
This is significantly different from book / 50 Hz. For this reason, the number of pixels of a solid-state imaging device used for a video camera, for example, a CCD is as follows: NTSC system: 510 (H) × 492 (V), P
For the AL system: CCDs dedicated to each system such as 500 (H) × 582 (V) are used. Therefore, using the conventional NTSC video camera C (N) shown in FIG.
In order to obtain an AL signal, a PA is converted from an NTSC signal SVN using a method converter CON shown as an example in FIG.
It had to be converted to the L system signal SVP.

[0003] In FIG.
The subject image formed above is taken out of the CCD 2 as a video signal by driving the H and V drive circuits 3 and 4 controlled by the timing generator 5. This video signal is subjected to signal processing such as clamping and gamma correction in a process amplifier circuit 7 after amplification and automatic gain control by an automatic gain control circuit (AGC) 6. Process amplification circuit 7
Are supplied to the encoder 8. On the other hand, the luminance signal Y output from the process amplification circuit 7 is supplied to a gamma correction circuit 8 and a luminance amplification circuit 9.
, And the encoder 10 converts the signals RY, BY, and Y into NTSC video signals SVN.
Convert to

The NTSC video signal SVN is converted to PAL
In order to convert to the format video signal SVP, a format converter CON as shown in FIG. 7 is used. In FIG. 7, an input NTSC video signal SVN is separated by a Y / C separation circuit 52 into a luminance signal YN and a chroma signal CN. The luminance signal YN is input to an A / D converter 54Y via a low-pass filter (LPF) 53, and is written as digital data in a memory circuit 55Y. On the other hand, the chroma signal C
N is input to a color demodulation circuit 60 via a band pass filter (BPF) 59 and demodulated into color difference signals RN-YN and BN-YN. The color difference signals RN-YN are digitized by the A / D converter 54R and then written to the memory circuit 55R. Similarly, the color difference signal BN-YN is output from the A / D converter 54B.
After that, the data is written into the memory circuit 55B. Here, the memory circuits 55Y, 55R, 55
The writing of each digital data to B is controlled by the controller 64 based on the synchronization signals HD and VD separated from the NTSC video signal SVN by the synchronization separation circuit 63.

After writing digital data in field units, digital data is read from the memory circuits 55Y, 55R, and 55B in accordance with the PAL system under the control of the controller 64. The read digital data is stored in D / A converters 56Y, 56R, 56B.
Analogized by the LPFs 57Y, 57R, 57
A luminance signal YP, color difference signals RP-YP, BP-YP via B
Becomes The color difference signals RP-YP and BP-YP are supplied to a color modulation circuit 61.
As a result, the signal becomes a chroma signal CP, and is added to the luminance signal YP in the adding circuit 58 to obtain a PAL video signal SVP.

[0006]

Recently, there has been an increasing demand for conversion from the NTSC system to the PAL system due to exchange of video letters with European countries. There were challenges.

The system converter CON shown in FIG. 7 has a digital memory and performs a field number conversion and a scanning line number interpolation process. Therefore, the system conversion device CON is a large-scale and expensive device. It was not suitable for mounting on a video camera.

Further, as described above, separation of the luminance signal YN and the chroma signal CN, A / D conversion, interpolation of the number of scanning lines, field number conversion, D / A conversion, synthesis of the luminance signal YP and the chroma signal CP, etc. However, there is a disadvantage that the image quality is degraded by the signal processing.

The present invention proposes an NTSC video camera that is simple, lightweight, inexpensive, and outputs a PAL signal without deteriorating image quality in order to solve the above-mentioned problems.

[0010]

Accordingly, in an NTSC video camera with a PAL signal output according to the present invention which has been made to solve the above-mentioned problems, an output signal is designated to either the NTSC system or the PAL system. And a control circuit that generates a vertical clock signal and a horizontal clock signal according to the NTSC system when the system specified by the control circuit is the NTSC system. When the PAL system is specified by the control circuit, A timing generation circuit for generating a vertical clock signal according to the PAL system and a horizontal clock signal having a shorter clock cycle than the horizontal clock signal according to the PAL system; and a timing generation circuit when the PAL system is designated by the control circuit. A masking processing circuit for masking the generated vertical clock signal and horizontal clock signal; A drive circuit for reading signals from the solid-state imaging device for the NTSC system using the vertical clock signal and the horizontal clock signal according to the C system, or the vertical clock signal and the horizontal clock signal masked by the masking processing circuit. In the timing generation circuit, when a signal is read from the NTSC system solid-state imaging device using a vertical clock signal corresponding to the PAL system, a clock of a horizontal clock signal is obtained so that a captured image having a predetermined aspect ratio can be obtained. Set the cycle,
The masking processing circuit masks the vertical clock signal and the horizontal clock signal so that the image captured by the solid-state image sensor for the NTSC system is located at the center of the screen and a mask is set at the periphery of the captured image.

[0011]

An NTS with a PAL signal output according to the present invention
In the C system video camera C (N + P), the system switching signal PA output from the control circuit 11 as shown in FIG.
L / bar NTSC causes the timing generator 12 to
Clock and synchronization signals S1, S3, HD, VD, O / bar E required to output AL or NTSC signal
Is output.

When trying to obtain a PAL signal,
Control circuit 1 based on synchronization signals HD, VD, O / bar E
The masking processing circuit 13 performs a masking process on the clock signals S1 and S3 in response to the mask signal S4 output by 1 and outputs read clock signals S2 and S5.

Under the control of the read clock signals S2 and S5, the drive circuits 3 and 4 are driven by the NTSC CCD 2
As a result, the CCD 2 outputs a PAL system video signal in which an NTSC system image is fitted in the center of the screen.

[0014]

Next, an embodiment of a video camera C (N + P) with a PAL signal output according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention. The same components as those of the conventional example shown in FIG. 7 are denoted by the same reference numerals, and the description thereof will not be repeated.

In FIG. 1, the control circuit 11 outputs a system switching signal PAL / NTSC to the timing generation circuit 12 to designate either the PAL system or the NTSC system. The designation is performed by a system selection switch (not shown) provided on the video camera body (not shown). The operation when the NTSC system is specified is the same as that of the conventional example shown in FIG. 7, but the case where the PAL system is specified will be described below.

The timing generation circuit 12 receiving the system switching signal PAL outputs clock signals S1 and S3, synchronizing signals HD, VD, and O / E required for constructing the PAL system signal. Based on the synchronization signals HD, VD, and O / bar E, the control circuit 11 outputs a mask signal required for fitting the video signal from the NTSC CCD 2 into the PAL field (hereinafter, referred to as "masking").

The masking processing circuit 13 masks the clock signals S1 and S3 input by the mask signal and outputs read clock signals S2 and S5 for reading a video signal from the CCD 2. Based on the read clock signals S2 and S5, the drive circuits 3 and 4
The CCD 2 for NTSC is driven to obtain a PAL video signal. Subsequent signal processing on the PAL video signal is the same as in the related art.

FIG. 2 is an explanatory diagram showing the correspondence between the operations of the control circuit 11, the timing generation circuit 12, and the masking processing circuit 13 described above, the configuration of the PAL system field signal, and the PAL system screen.

As described above, the solid-state image pickup device has a CCD 2 for NTSC system having 510 (H) × 492 (V) pixels as described above.
Is C for PAL system with 500 (H) × 582 (V) pixels
A case where the PAL video signal SVP is generated instead of a CD will be described. As shown in FIG. 2A, 291 out of 312.5 scanning lines per field are used.
The book constitutes an effective screen of the PAL system. Here, this effective screen is actually composed of 287.5 lines, but for the purpose of explanation, it is simply 58 58 per field.
Handle as 2 (V) / 2. Hereinafter, the number of pixels per scanning line in the PAL system (500 pixels), the number of scanning lines per field in the NTSC system (246 lines), and the number of pixels per scanning line (5
(10 pixels).

In the present invention, 246 out of the 291 scanning lines constituting the effective screen are used in the NTSC system CC.
The data is read from D2, and the shortage of 45 lines is sorted up and down to form a black level mask region. The above is the outline of the vertical reading process. That is, the vertical readout of the CCD 2 is performed at the normal PAL readout timing in which upper and lower portions are masked.

On the other hand, horizontal reading is performed by a normal PAL.
FIG. 2A shows the case where the reading is performed at the system readout timing.
The video is displayed in the flat image area shown in FIG. This screen becomes a horizontally flat image compressed up and down in proportion to the scanning line number ratio (246 lines / 291 lines). To restore the flat image to normal, the read clock cycle in the horizontal direction may be reduced by the same ratio. That is, as shown in FIG. 2B, the number of clocks per scanning line is changed from 615 clocks to 728 clocks. At this time, out of the 603 pixels constituting the effective screen, 93 pixels, which are insufficient for the 510 pixels of the NTSC CCD, are distributed to the left and right for mask processing.

The image thus obtained is shown in FIG.
As shown as an image area in (B), an NTSC system screen is fitted in the center of the PAL system effective screen,
The entire captured image can be displayed in an easily viewable manner. Also, the mask area around the image area is not so large as shown in the figure, and most of this mask area is hidden by the display frame of the picture tube on the actual display screen. No.

As is well known, reading of the CCD 2 is performed as follows.
Since driving by two-phase horizontal and four-phase vertical clock signals is common, the above-described description, for example, 510 clocks for reading 510 pixels is a simplification for the sake of convenience. The same applies to the description.

FIGS. 3 and 4 are waveform diagrams for explaining signal processing when the above-described PAL signal output is selected. In the figure, a masking processing circuit 13 performs a masking process on a PAL type clock signal S3 received from the timing generation circuit 12 based on a mask signal S4 supplied from the control circuit 12, and outputs a vertical read clock signal S3.
5 is output. As shown, the mask for the PAL screen has 23 scan lines at the upper edge and 22 scan lines at the lower edge.

FIG. 4A is a waveform diagram showing a horizontal clock signal corresponding to FIG. 2A, and FIG. 4B is a waveform diagram showing a horizontal clock signal corresponding to FIG. 2B. FIG.
The number of clocks per line 615 in FIG. 4A is 728 in number of clocks per line in FIG. 4B, and the ratio of the number of scanning lines in the vertical direction (246 lines / 291 lines) for correcting a flat image. The time axis conversion proportional to is performed.

Note that such time axis conversion is not limited to the above-described method of changing the frequency of the CCD read clock signal, but may be performed by, for example, the following well-known configuration. That is, two 1H delay lines (line memories) are provided, and reading from the CCD 2 dedicated to the NTSC system is performed using a normal horizontal read clock signal (FIG. 4A). input. This 1H
The horizontal read clock signal S2 is used for reading from the delay line.
Using FIG. 4B, the time axis is converted alternately for each line. The vertical reading is performed in the same manner as described above.
In the embodiment using such a 1H delay line, since the frequency of the horizontal readout signal is substantially the same as that in the case of using the CCD dedicated to the PAL system, correlated double sampling or the like performed to reduce noise in the obtained video signal is used. It is advantageous in the point.

In FIG. 4B, a masking processing circuit 13 performs a masking process on a mask area on the left and right sides of the screen with a mask signal S4 supplied from the control circuit 11 in response to the horizontal clock signal S1 output from the timing generation circuit 12. And outputs a horizontal read clock signal S2. As shown, this mask area is 47 pixels at the left end of the screen and 4 pixels at the right end.
6 pixels. As described above, the control circuit 11 outputs the system switching signal P
This is the operation when AL is output to set the output mode of the PAL system.

FIG. 5 is a waveform diagram showing signals when the output mode is set to the NTSC system. As shown, the mask signal S4 output from the control circuit 11 is always at a high level, that is, the masking processing by the masking processing circuit 13 is not performed, so that the operation is the same as the conventional example.

Although the above description has been limited to the NTSC video camera with the PAL signal output, the SECAM signal output with a simple change is described.
Or NT with PAL and SECAM signal output
An SC video camera may be used.

[0031]

According to the present invention, a simple control circuit, a timing generation circuit and a masking processing circuit replace the conventional large-scale and expensive system conversion apparatus.
A PAL video signal can be obtained directly from the TSC-dedicated CCD.

For this reason, by providing an extremely small, lightweight, inexpensive and low power consumption circuit integrally with the NTSC video camera, there is an effect that the output of the PAL or NTSC video signal can be arbitrarily selected.

The PAL video signal output has the effect of being free from image quality deterioration and the like accompanying the format conversion processing.

[Brief description of the drawings]

FIG. 1 shows an NTS with a PAL signal output according to the present invention.
FIG. 1 is a block diagram illustrating an embodiment of a C-system video camera.

FIG. 2 is an explanatory diagram showing a correspondence between an operation of the video camera and a display screen.

FIG. 3 is a waveform diagram showing signals in the PAL system in the video camera.

FIG. 4 is a waveform diagram showing signals in the PAL system in the video camera.

FIG. 5 is a waveform diagram showing signals in the NTSC system in the video camera.

FIG. 6 is a block diagram showing an example of a conventional NTSC video camera.

FIG. 7 is a block diagram showing an example of a conventional system conversion device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lens 2 CCD for NTSC system 3 Horizontal drive circuit 4 Vertical drive circuit 11 Control circuit 12 Timing generation circuit 13 Masking processing circuit

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04N 5/225 H04N 5/335

Claims (1)

(57) [Claims] An NSC having a solid-state imaging device for an NTSC system.
In a TSC video camera, a control circuit that specifies an output signal to be either an NTSC system or a PAL system; and, when the system specified by the control circuit is the NTSC system, a vertical clock signal corresponding to the NTSC system and When a horizontal clock signal is generated and a PAL system is designated by the control circuit, a vertical clock signal according to the PAL system and a horizontal clock signal having a shorter clock cycle than the horizontal clock signal according to the PAL system are generated. A timing generation circuit; a masking processing circuit for masking a vertical clock signal and a horizontal clock signal generated by the timing generation circuit when the control circuit specifies the PAL system; and a vertical clock signal according to the NTSC system. And horizontal clock signal or masking processing circuit. A drive circuit for reading signals from the NTSC system solid-state image pickup device using the vertical clock signal and the horizontal clock signal subjected to the sking process; and the timing generation circuit uses a vertical clock signal according to the PAL system. The clock cycle of the horizontal clock signal is set so that a captured image having a predetermined aspect ratio is obtained when a signal is read out from the NTSC system solid-state image sensor by using the NTSC system. Wherein the vertical clock signal and the horizontal clock signal are masked so that a captured image of the solid-state imaging device for use is located at the center of the screen and a mask is set at the periphery of the captured image. NTSC video camera.