JP2997032B2 - Television signal transmission equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television signal transmission device, and more particularly to a television signal transmission device for improving the dynamic resolution of a television image.

SUMMARY OF THE INVENTION The present invention is directed to a television signal transmission device, for a 2: 1 interlaced scanning television system having a certain field frequency, with two consecutive fields scanning odd numbered scanning lines. And two consecutive fields for scanning even-numbered scanning lines.
An image is captured by a 4: 2 interlaced scanning camera that forms one frame with fields, and only the first, third or second and fourth fields of the camera output signal are extracted, and the time axis of the extracted signal is set to 2 It expands the image twice and transmits it as a 2: 1 interlace signal, thereby improving the dynamic resolution of the television image.

(Prior Art) As a method of improving the dynamic resolution of a television, conventionally, besides improving an electronic circuit of an imaging device or a camera, a shutter is used to mechanically limit light incident on the camera for a short time. There was a way. Although it is not often used, a method of simply doubling the field frequency of 2: 1 interlaced scanning, or simply performing imaging at twice the field frequency, and then scanning the signal to the original field frequency A method of conversion is conceivable.

(Problems to be Solved by the Invention) However, in the above-mentioned improvement of the current camera, the degree of the improvement is naturally limited. Further, the method using the shutter requires a mechanical mechanism, which makes the handling of the camera inconvenient. Besides, the causes of the deterioration of the dynamic resolution in the camera include accumulated blur and an afterimage, but the improvement by the shutter is limited to the former. There was a problem.

Further, in the method of simply doubling the field frequency, it is necessary to double the signal band over the entire television system, so that there is a problem that the required cost increases. Furthermore, in the method of simply doubling the imaging, interpolation processing is required in scan conversion of a signal as described later, so that the conversion processing becomes complicated and the vertical spatial frequency characteristics are deteriorated. Further, as described later, there is a problem that the deterioration due to the afterimage is not improved.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a television signal transmission apparatus in which the scanning blur and only the accumulated blur on the receiving side and both the accumulated blur and the afterimage are easily and completely electronically changed by changing the scanning and signal processing methods only on the imaging side. It is an object of the present invention to provide a television signal transmission device which can be improved by various means.

Means for Solving the Problems In order to achieve this object, a television signal transmitting apparatus according to the present invention comprises two consecutive fields for scanning odd-numbered scanning lines in a television image frame;
4: 2 interlaced scanning image capturing means, which comprises two continuous fields for scanning even-numbered scanning lines, and constitutes one frame with four fields. Field thinning-out means for extracting a field signal on the front side or rear side of a field of two odd-numbered scanning lines and two even-numbered scanning lines, and a transmission signal obtained by time-expanding the field signal extracted by the means by a factor of two. At least a time axis extending means for generating a 2: 1 interlace signal.

(Example) Hereinafter, the present invention will be described in detail by way of examples with reference to the accompanying drawings.

FIG. 1 shows a schematic block diagram of a configuration of an embodiment according to the transmission apparatus of the present invention.

The television system currently used in Japan is NTSC
Scanning is performed by 2: 1 interlace with a field frequency of 60 Hz in both the system and the high-definition (HDTV) system. In the configuration of the embodiment of the transmission apparatus of the present invention shown in FIG. 1, the camera 1 is a television camera that scans at a double speed of 60 Hz at 120 Hz and 4: 2 interlace. The output of the camera 1 is input to the field thinning circuit 2. In the circuit 2, for example, only the second and fourth fields are extracted from the signal of the 4: 2 interlace scanning and output. The output of the circuit 2 is extended to twice the time by the time axis extending circuit 3,
It will be a normal 60Hz / 2: 1 interlaced television signal. Therefore, circuits 2 and 3 as a whole are 120Hz / 4: 2 to 60Hz /
A 2: 1 scan converter 4 is configured. The output signal of the converter 4 can be viewed on a normal monitor 5 that scans at 60 Hz / 2: 1 interlace.

Next, 4: 2 interlace scanning and its scan conversion will be described with reference to FIG. In the 4: 2 interlaced scanning, one frame is composed of four fields as shown on the left side of FIG. If the first field (Δ mark: scan line to be thinned out) and the second field (o mark: scan line to be converted) are, for example, fields for scanning odd-numbered scan lines in a frame, the third field (Δ mark: ), 4th field (○)
Are fields for scanning even-numbered scanning lines. Therefore, in the vertical direction y of the screen, the first field (Δ)
And the second field (○) scan the same position, and the third field (フ ィ ー ル ド) and the fourth field (位置) scan the same position that is shifted from the first and second fields by 1/2 scanning line interval. . To convert a 4: 2 interlaced scanned image having a field frequency of 120 Hz to a normal 60 Hz 2: 1 interlaced image, as shown in FIG.
In the second embodiment, the second field and the fourth field are extracted, and the time axis may be doubled by writing to or reading from the memory element. This situation is shown in FIG. 3 by a signal waveform. The expanded signal is a normal 60 Hz, 2: 1 interlace signal as shown on the right side of FIG. The upper signal waveform in FIG. 3 is the input signal (120 Hz / 4: 2 signal) of the first illustrated element 4, and the lower signal waveform is the same as the illustrated element 4.
Is a waveform of each output signal (60 Hz / 2: 1 signal).

In order to explain one aspect of the effect of the present invention, as an example, 12
FIG. 4 shows an example of a conversion process when converting from 0 Hz / 2: 1 interlaced scanning to 60 Hz / 2: 1 interlaced scanning. In order to convert from the 120 Hz / 2: 1 interlaced scanning on the left side of the figure to the 60 Hz / 2: 1 interlaced scanning on the right side, for example, extract the second field of the first frame on the left side (印: scanning line to be directly converted) It is assumed that the time axis is extended and converted to become the first field of the first frame on the right side (marked by ○: directly converted scanning line). Then, the field to be converted next is the second field of the second frame on the left (Δ mark: scan line to be thinned out, ● mark: position of the scan line to be interpolated). Are scanned at the same position as the second field of the first frame. Therefore, a 2: 1 interlace signal cannot be obtained simply by time-expanding the signal in this field as it is, and an interpolation scan line is created by interpolation at the position indicated by the black circle in the left figure, and the interpolation scan line is time-expanded. Then, it is necessary to set it as the second field of the first frame (indicated by ●: interpolated and converted scanning line) in the figure on the right. However, the signal is band-limited with respect to the vertical spatial frequency by this interpolation processing, and the vertical resolution of the image is degraded. Further, the scan conversion process becomes complicated. According to the present invention, as shown in FIG. 2, all the scanning lines can be converted only by time expansion, and the above problems do not occur.

Further, another aspect of the effect of the present invention will be described with reference to FIGS. FIG. 5 shows a state of an afterimage in a normal 2: 1 interlace. The camera's image pickup tube accumulates incident light as electric charges on the conductive film by photoelectric conversion,
Light is converted into an electric signal by reading the stored signal with an electron beam from an electron gun. At this time, the longer the charge accumulating time is, the longer the integration time with respect to the incident light is, and the dynamic resolution of an image is deteriorated. This effect is called accumulation blur, but its effect is almost determined by the field frequency when the shutter is not used.
The higher the field frequency, the better the dynamic resolution. In the present invention, since the imaging is performed at twice the normal field frequency, the accumulated blur is reduced to half. However, this effect is the same even when a 120 Hz / 2: 1 interlace is used as shown in FIG. However, the situation is different for the afterimage, which is another factor of deteriorating the dynamic resolution, as follows.

In the normal 2: 1 / interlaced scanning shown in FIG. 5, it is assumed that light is incident only on the first field and no light is incident on the second field. In the first field (in this case, Δ mark: scanning line to be decimated), the charges converted from the incident light are read by a beam. At this time, since the beam from the electron gun is not rectangular, the charges as shown by oblique lines in the figure are used. Is left between the scanning lines. For 2: 1 interlace,
As shown in the figure, this is the second field (in this case, circle:
(Scanning line to be converted) and causes an afterimage.

On the other hand, according to the present invention as shown in FIG.
Even if the same residual reading occurs for the same incident light as that in the figure, the residual reading is hardly read out in the second and fourth fields to be scan-converted (indicated by a circle: the scanning line to be converted). In 1: 1 interlaced scanning, it is possible to obtain an image signal with low afterimage.

The first embodiment described in detail above corresponds to the case where the rear field signal is extracted in the claims of the present invention, and the case where the front field signal is extracted in the claims. In the second embodiment corresponding to FIG. 6, the diagram showing the state of the afterimage is a form in which the thinned-out scanning line Δ and the converted scanning line ○ are exchanged in FIG. 6. In this case, the converted The third field scanning line contains an afterimage component due to the unread image, and is not as effective as the case of extracting the rear field signal. However, the effect of preventing the deterioration of the moving resolution by increasing the scanning speed of the scanning on the imaging side remains as it is.

The embodiment described above is not limited to this, and it is obvious that various modifications and changes can be made within the gist of the invention described in the appended claims. The present invention can be applied to a field frequency other than the described field frequency, and the number of scanning lines can be applied to an arbitrary number of systems.

(Effects of the Invention) According to the transmission apparatus of the present invention described in detail above, the storage blur on the reception side or both the storage blur and the afterimage can be compared only by changing the method of scanning and signal processing only on the imaging side. It has become possible to provide a television signal transmission device which can be improved by a simple and all-electronic method.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of a configuration of an embodiment according to the transmission apparatus of the present invention, FIG. 2 is a diagram showing a scanning line structure of a scanning method and scan conversion processing in the transmission apparatus of the present invention, and FIG. FIG. 4 is a diagram showing an example of a signal waveform of scan conversion in FIG. 4, FIG. 4 is a diagram showing another example of double-speed 2: 1 interlace scanning and its scan conversion processing, and FIGS. FIG. 7 is a diagram for explaining a state of an afterimage in 4: 2 interlaced scanning according to the present invention. 1. Camera (120Hz / 4: 2) 2. Field thinning circuit 3. Time axis expansion circuit 4. Scan converter (120Hz / 4: 2 → 60Hz / 2: 1) 5. Monitor (60Hz / 2: 1)

Claims (1)

(57) [Claims] 1. A frame is composed of four fields consisting of two continuous fields for scanning odd-numbered scanning lines and two continuous fields for scanning even-numbered scanning lines in a television image frame. 4: 2 interlaced scanning image capturing means, 4: 2 produced by the means
Field thinning-out means for extracting field signals on the front side or rear side of two consecutive odd-numbered scan line fields and two even-numbered scan line fields, respectively, from the interlaced scan image signal, and extracting the field signals extracted by the means, respectively. An apparatus for transmitting a television signal, comprising at least time-base expansion means for generating a 2: 1 interlace signal as a transmission signal by performing time-base expansion twice.