JPH01194781A - Television signal system converting device - Google Patents

Abstract

PURPOSE:To easily convert the TV system by employing a field memory to store one-field-length of digitized TV signals. CONSTITUTION:An input signal 1 of, for instance, 625/50-system, is A/D- converted 2 and transmitted to a scanning line interpolation circuit 3. In the circuit 3, interpolation is executed in order to convert the number of lines per one frame of the signals from 625 to 525. And an output signal from the circuit 3 is written in the field memory 4 in accordance with an address generated by a write address genera tion circuit 6 and a timing signal generated by a timing control circuit 8. At this very time, the signals of the 625-lines-per-frame- system only are written in the memory 4. Only, since the capacity of the memory 4 is just for one field, the signals are written in superimposition in the unit of field. In the meantime, the signals stored in the memory 4 are read out in accordance with an address generated by a read address generation circuit 7 and a timing signal generated by the circuit 8, D/A-converted 5, then outputted 9.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a television signal format conversion device for converting a television signal into a television signal of another format having a different field frequency. The television system used in Japan has 625 scanning lines and a field frequency of 5oHz (
(hereinafter abbreviated as 625150 method) and the number of scanning lines is 526.
In the book, the field frequency is aoHzO method (hereinafter 525/
(abbreviated as 60 methods).

A device that converts a television signal into a television signal of another format with a different number of scanning lines and a different field frequency has been known as a television standard format converter, for example, as described in TV Society Journal, Vol. 29, No. 10. Its contents are described in the issue ``Recent Television Standard Conversion Devices''. Since the main purpose of this conventional conversion device is to operate at broadcasting stations, the converted television signal must also meet strict standards, and the conversion of the number of fields requires In order to reduce the unnaturalness of moving images, the configuration is complicated and expensive, such as having at least two fields of memory and performing field interpolation.

Problems to be Solved by the Invention However, when converting the television format using general consumer video equipment, such as a television receiver or video tape recorder (hereinafter abbreviated as VTR), the converted signal does not necessarily meet strict standards. It is not necessary to satisfy the standards, and a low-cost device that is practical for consumer use is desired even if some unnatural movement remains.

In view of the above-mentioned points, the present invention provides a television signal format converting device that realizes format conversion of television signals with a simple configuration that uses one field's worth of memory.

Means for Solving the Problems In order to solve the above problems, the television signal format conversion device of the present invention includes a memory for storing one field of a digitized television signal, and a signal writing device for writing the above signal into the memory. and a signal readout means for reading out field signals stored in the memory with a length different for signals on a certain line than for signals on other lines.

According to the above-described structure, the present invention converts a 62615° television signal into a 525/80 television signal while the 6n fields of the 625150 television signal are written into the memory field by field. Read the signal from memory, 5
When converting from a 25/60 television signal to a 625150 television signal, while the 6n field signals of the 525/60 television signal are written to the memory field by field, the 6n field signals can be read out from the memory. This results in the number of fields,
This means that it can be converted to a television signal of another system with a different number of lines.

Embodiment Hereinafter, a telepijo/format conversion device according to an embodiment of the present invention will be explained with reference to the drawings.
The figure is a diagram showing the configuration of a television signal format conversion device according to an embodiment of the present invention.

Figure 1 shows the 625150 system, and the television signal is 525.
The configuration for converting to /60 format television signal is as follows.
Figure 2 shows the 525/60 television signal as 6251.
This figure shows a configuration for converting to a V.50 format television signal. In the figure, 1 is the signal input terminal, 2 is the mu D
Converter, 3 is a scanning line interpolation circuit, 4 is a field memory,
6 is a zero-person converter, 6 is a write address generation circuit, 7 is a read address generation circuit, 8 is a timing control circuit,
9 is a signal output terminal. Note that the same blocks in FIG. 1 and FIG. 2 are given the same numbers.

The operation of the television signal format converter configured as described above will be described below.

First, the operation of converting a 625150 television signal into a 625/60 television signal will be described with reference to FIGS. 1 and 3.

In Figure 1, 6251 input from signal input terminal 1
The V.50 system signal is converted into a digital signal by the mu D converter 2 and sent to the scanning line interpolation circuit 3. Scanning line interpolation circuit 3
Then, scanning line interpolation is performed to convert a signal of 25 lines at the top into a signal of 625 lines per frame. It is well known that scanning line interpolation can be simply realized by multiplying two signals temporally different by one horizontal period by a certain weighting coefficient and then adding the signals. The output signal from the scanning line interpolation circuit 3 is written into the field memory 4 according to the address generated by the write address generation circuit 6 and the timing signal generated by the timing control circuit 8. At this time, only 525 lines of signals obtained by circular scanning line interpolation of 626 lines of signals per frame are written into the field memory (writing is prohibited during the remaining 1oO line (625-625)).
.

However, since the memory capacity is only for one field, 62
Six lines (one frame) of signals do not exist on the memory at the same time, but are written overlapping one field at a time. On the other hand, the signal stored in the field memory 4 is read out according to the address generated by the read address generation circuit 7 and the timing signal generated by the timing control circuit 8, and converted into an analog signal by the zero-person converter 6. The signal is output from the signal output terminal 9.

Figure 3 is an explanatory diagram for explaining the operation of field number conversion, and the horizontal length is 1 of the 625150 system signal.
It represents the time with a period of 0 field, and the upper line indicates the time period for each field period of the 625150 signal.
．． A2. Mu3. Mushimamu 5. Muro.

M7. Bo, B1 . B2. B3. B4. B.S.
, B.S.

B6. B7. Ba, B9. It is marked B+o. The subscript number of symbol B indicates that the signal written in the field memory 4 during the period of time having the same subscript number is read out during the period of B having that subscript number. However, during the BO period, the signal is written and read out one field before M1. Further, B5 is repeated twice, and during this time, the signal of the same field is repeatedly read out for two field periods. 625 as shown in the figure
12 of the 525/ao system signal from field memory 4 during the period of adjustment to the 10th field of the 150 system signal.
The number of fields is converted by reading signals for fields. By the way, in the NTSG color television system, the field frequency is approximately 60H2, but not exactly 60Hz (However, in this text, this signal will also be included as one of the 525/60 system signals). The length of the field period is 62515
This does not exactly match the length of the 10 field period of the 0 format signal.

For example, if the clock frequency of MU D conversion is 13.5 MHz
Then, for a 625/50 format signal, the number of pixels is 2,700,000 pixels per 10 fields (6 frames) (86,464 pixels per line, 540,000 pixels per frame), whereas for a 525/60 format signal (
For NTSC color television signals), there are 2702,700 pixels (1
868 pixels per line, 45045 pixels per frame
0 pixel), resulting in a difference of 2700 pixels.

If there is this difference, the read address of field memory 4 will overtake the write address (since 12 field signals are read while 10 field signals are written, the read address will exceed the write address by 2 times).
The address position will gradually shift.

When this overtaking address position comes to a visible position on the screen, a horizontal shift occurs above and below the overtaking address position on a moving screen. FIG. 6 shows this situation. The figure shows one frame of a video television screen in which a circular figure moves to the right, and the part where the figure is shifted in the horizontal direction at the center of the screen is the overtaking position of the address. In the area below the address overtaking position, a signal that is one field before the signal that has been read up to that point is read out, so on a moving screen, a shift as shown in the figure will occur.

In order to solve this problem, in the embodiment of the present invention, the number of pixels per 12 fields of the signal read from the field memory 4 matches the number of pixels per 10 fields of the 625150 signal (2,700,000 pixels). Controls reading of signals from memory 4. For example, the number of read pixels per line is usually 8.
5757 pixels, 1 field out of 2 fields is 1
By reading out the line length as 857+38 pixels and the length of one other field as 857-1-37 pixels, the number of pixels per 12 fields is s
57 x 525 x 6+(3B+37)X6=27
00,000 pixels, which corresponds to the number of pixels per 10 fields of the Shiro 25150 system signal.

This fixes the overtaking position of the Seadress, so
(If 12 fields of the 625150 signal are one cycle, there will be two address overtakes during that period, and there will be a slight deviation in the address overtake position between the two times, but this is not a particular problem.) By setting the overtaking position in an invisible part of the screen, there will be no lateral shift on the screen as described above.

In order to set the overtaking position in an invisible part of the screen, the read address generation counter and the write address generation counter are simultaneously reset at a cycle of 12 fields of the 625150 signal.

In addition, in the above method, the length of one line of the signal in one field is different from the signal length of the other lines, so when this signal is played back on a television screen, skew distortion as shown in Figure 6 occurs. occurs. However, in this case as well, by using a line near the vertical synchronization signal as the signal that changes the length of the line, the skew does not appear on the screen and is not a particular problem.

Above, we have explained the operation of converting a 625150 signal to a 525/60 signal.
The operation of converting a 0 system signal into a 625150 system signal will be explained with reference to FIGS. 2 and 4.

The basic operation is from 625150 system signal to 525/6
This is the same as when converting to a 0 system signal. The major difference in configuration is from 625150 signal to 525/60 signal.
When converting to a standard signal, scanning line interpolation is performed before writing the signal to the field memory 4, whereas
When converting from a 5/60 system signal to a 625750 system signal, this is done after reading from the field memory 4. In Fig. 2, the MuD converter 2
The digitized signal is directly written into the field memory 4 as a signal of 25 lines per frame, while the signal read out from the field memory 4 is processed by the scanning line interpolation circuit 3, which converts the signal into a signal of 525 lines per frame. , scanning line interpolation is carried out into a signal of 625 lines per frame, and the signal is sent to the DMU converter 5.

In addition, when converting from a 625150 signal to a 525/60 signal, the number of lines is reduced from 625 lines per frame to 525 lines per frame, so one line for every few lines is stored in the field memory 4. Prohibits writing of signals, but 525/60
When converting from a 625750 system signal to a 625750 system signal, conversely, in order to increase the number of lines from a 526-line signal per frame to a 626-line signal, the same line must be read twice at a rate of once every few lines. becomes. The number of lines is converted as described above.

Next, the operation of converting the number of fields will be explained with reference to FIG. Figure 4 is an explanatory diagram for explaining the operation of field number conversion.The horizontal length represents the time with a period of 12 fields of the 526780 system signal, and the upper line A shows the 525/60 system signal. For each field period of the signal, M1. Mu2. Mu3. M4゜m5. Muro, M7. M8.
M9. Mu10. M11. The line B at the bottom of the figure shows B1 . B2. B3. B4.
BS, B7. B8. B9. B10. It is marked B11. The meanings of the subscript numbers are the same as in FIG. 5
When converting a 25/60 system signal to a 625150 system signal, during a period K during which 12 fields of the 525/60 system signal are written into the field memory 4, a 1° field worth of signals is read out from the field memory 4. Therefore, the signal for two fields (in Fig. 4, Muro and M1
2) is not read out.

In order to read exactly 10 fields of signals in a period corresponding to 12 fields of the 525/60 signal, the same method as in the case of converting the 825/50 signal to the 525/60 signal described above is used. That is, the number of pixels per 12 fields (6 frames) of a 525/60 system signal (HTSG color television signal) is 27o27o when the sample 1)711 frequency is 13.5 MHz.

Since the number of pixels is (858X525X6=2702700), the number of pixels per 10 fields of the signal read from the field memory 4 is made equal to this number of pixels (2702700 pixels).

For example, if the number of pixels per line is normally 865, one field out of the two fields reads out a certain line as a signal of 865-42 pixels, and the other one field reads out a certain line as a signal of 865-43 pixels. Realizable (865X625X5-(42-)-43)X5=27
02700).

As described above, 82t is obtained from the 525/60 signal.
Conversion to s/50 system signals can be realized.

In addition, in the embodiment of the present invention, the 625150 system signal is
2. A configuration for converting to a ts/eo system signal, and 5.
The configuration for converting the E.215/60 format signal to the E.25/50 format signal is shown separately in Figures 1 and 2, but the configuration of Figures 1 and 2 can be changed by switching the signal flow with a switch. Of course, it is possible to share some or all of the blocks with the same number. It is therefore also possible to perform bidirectional conversion with a single device.

Effects of the Invention As described above, according to the present invention, it is possible to obtain the excellent effect that television formats can be easily converted using a field memory that stores one field of a digitized television signal.

'When using the present invention in a digital television or digital VTR that has a built-in field memory,
By sharing a converter, a zero-person converter, and a field memory, it is possible to convert television formats at an extremely low cost, which is highly effective.

[Brief explanation of the drawing]

1 and 2 are block diagrams showing the configuration of a television signal format conversion device according to an embodiment of the present invention, and FIGS.
The figure is a schematic diagram for explaining the operation of an embodiment of the present invention. 1... Signal input terminal, 2... MuD converter, 3... Scanning line interpolation circuit, 4... Old field memory, 5... 0 person converter, 6... mark/write address generation circuit, 7... read address generation circuit, 8... river/timing control circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Fig. 2 <rQ<2 Material Fig. 5 Fig. 6

Claims (1)

[Claims] a memory for storing approximately one field of a digitized television signal; a signal writing means for writing the television signal into the memory; and K and n fields of the television signal (where K and n are positive integers); ) for sequentially reading signals for L·n fields (where L is a positive integer) from the memory during a period in which the field is stored field by field in the memory, and the signal reading means reads one field signal. 1. A television signal format conversion device characterized in that a signal on a predetermined line is read out with a length different from signals on other lines.