JPS5915371A - Converter for number of scanning lines - Google Patents

Abstract

PURPOSE:To convert the number of scanning lines, by using three CCDs to write the signal of the 1st scanning system into the CCDs with the writing clock of the 1st frequency by an amount equivalent to one horizontal scan period, then reading out repetitively the written signal with the reading clock of the 2nd frequency. CONSTITUTION:The signals supplied to input terminals Xin and Yin are distributed to three parts and transmitted to input switches 1, 4 and 7 to be fed to three CCDs 2, 5 and 8 respectively. The outputs supplied from CCD driving clock oscillating circuits 13 and 14 of frequencies fC1 and fC2 are gated with control pulses W-1-3 and R-1-3 to perform switching between writing and reading clocks W'1-3 and R'1-3 of the CCD2, 5 and 8. The signals of R-1-3 are applied to buffers 3, 6 and 9 respectively, and these buffers are controlled to deliver outputs only when the signals of R-1-3 are at high levels respectively. The output signals fed from those three buffers are added together at an adder circuit 10, then delivered to output terminals Xout and Yout in the form of converted signals of the 2nd horizontal scanning system.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a scanning line number conversion device for matching the number of scanning lines when receiving two television signals having different horizontal scanning periods.

Conventional configuration and its problems The image transmission method divides the screen horizontally and sends it out.
Basically, the receiving side scans and reproduces the screen in synchronization with the transmitting side. This number of horizontal scans is determined by one transmission method, and it is impossible to reproduce signals with different numbers of horizontal scans.

However, if the currently proposed 1,126-line horizontal scanning high-definition television broadcasting begins, there will be two types of systems in addition to the current NTSC system, and a separate television receiver will be required. However, if the vertical frequencies are the same, it is only necessary to convert the number of scans so that a signal scanned at a lower horizontal frequency can be received by a receiver that scans at a higher horizontal frequency.

On the other hand, various format conversion devices for converting from the NTSC format with different horizontal scanning periods to the PAL format or SECAM format, or vice versa, have been proposed and are currently being used at broadcasting stations, but these devices are expensive A/ Most digital image processing devices using D converters, D/A converters, memories, etc. are not designed with consideration for incorporation into commercially available television receivers.

However, when broadcasting in other formats such as high-definition television broadcasting begins, a receiver that can also receive NTSC format and high-definition Internet television is required, and the system that can be incorporated into such a receiver is required. One important condition is that the conversion device be inexpensive.

Purpose of the Invention The purpose of the present invention is to realize a system conversion device having the necessary performance by using a relatively inexpensive charge transfer device (COD) without using an expensive digital element. .

Structure of the Invention In the present invention, three CODs are used, and a signal of the first scanning method is written to the COD for one horizontal scanning period using a single write clock of the first frequency, and then a read clock of the second frequency is used. It's repeated.

DESCRIPTION OF THE EMBODIMENTS One horizontal scanning period of the television signals of two types of scanning methods as shown in FIG.
TH2), THl”” TH2+Δt −−・・−(
1) (n is an integer) Δt<TH2・・・・−・・・・・・・(2
).

In order to convert the signal of the first scanning method (scanning period TH1) to the second scanning method (scanning period TH2), the signal transmitted in THl must be time-compressed and reproduced in TH2. .

When using COD, if the number of stages of COD is N, then by using the write clock fc1, THl
One horizontal scanning period can be loaded into the CCDK@. During the write, stop the write clock fc1 during write X7 for the TH1 period and hold it as it is until the beginning of the horizontal scanning period of the second method, and then read the signal from the COD repeatedly with the next read clock. If it is output, it is possible to read out the proper length signal written during the T output period during the TH2 period. In this way, the COD is used as a time compression element.

Hereinafter, for the sake of simplicity, the description will be made assuming that n shown in equation (1) is 2.

As shown in Figure 2, the signal A of the first scanning method is
In order to convert to signal B of the scanning method, CO
The signal written to D must be read out twice or more. In order to read out a signal written in the COD multiple times, the output of the COD may be returned to the input through a buffer circuit as shown in FIG. 2, and the data may be written and transferred using the same clock as the read clock fC2.

Now, in FIG. 2, the signal A of the first scanning method and the signal A of the second scanning method
With the scanning method signal B, Δt as shown in FIG.
The time at which horizontal scanning starts is not constant due to the time lag.

If, instead, a signal written in THl is read out in fc2 immediately after THl ends, the signal will be out of phase with TH2. Therefore, the signal must be held for a period of time Δt1 from the end of TH1 to the start of TH2 immediately after.

When the COD is used normally, it only functions as a shift register for analog signals and has no storage function. In the present invention, we focus on the fact that by stopping the transfer lock of the COD, the charge stored inside the COD at that point can be held at that point, and when the THl ends, the clock is switched for Δt1-2. By stopping the signal and then reading it with a clock fC2, the signal can be converted regardless of the phase difference between the horizontal periods of the first method and the second method. This kind of behavior is
A minimum of three CODs are required to write the entire period to the signal of the first horizontal scanning method using OD and read out the entire period as the signal B of the second horizontal scanning method.
Figures C, D, and E show the timing of each COD.

In order to operate these three CODs, it is necessary to set the fcl write clock to each COD during the write period W.
and at the same time close the input ports of those CCDs to the input A side of the first horizontal scanning system signal.
It is possible to write signals using the following methods.

After that, during the holding period H, the clock is stopped and held by Δt, and then during the reading period R, the fc2 clock is applied to each COD.
At the same time, by switching the input signal to the output side of the COD which is outputted through the buffer circuit, the signals of each COD are alternately switched and outputted repeatedly to obtain the second horizontal scanning signal B. can be converted.

During times other than the write/read period, the COD does not write or read signals, and holds the signal written immediately before.

The overall configuration of a device that realizes such an operation will be described with reference to FIG. 3.

In general, a composite signal method and a component method (Y/C or R, Ci, B) are considered for color signal transmission, but if the composite signal method is used, the color subcarrier must also be converted.
The above-mentioned method cannot perform conversion with exact fidelity.

This apparatus employs a two-channel system as shown in FIG. 3, and converts the luminance signal and the color signal or two color difference signals, respectively. In the figure, X is a brightness circuit, Y is a color circuit, and both have the same configuration.

Of course, converting RGBS colors using 3 channels is also possible with 5 channels, but in that case, you will need 3 more CODs.

The signals input to the input terminals Xin and Yin are distributed into three parts and transmitted to the human Kasuinochi 1.4.7, respectively. This input switch is opened and closed at the timing of W-1, W-2°W-3, and the three C0D2, cs, -
are input to each of a. On the other hand, the synchronous control circuit 1 generates control pulses that determine the writing and reading timing of the CCD 2° 5.8 from the horizontal frequencies fH1 and fH2 of the two methods.
6 and a switching circuit 16.

Oscillation circuit 1 for CCD driving clocks fol and fo2
3. The output from
C0D2,s gated with R-1 to R-3.

8 write clocks and read clocks W'1-3°R'1-3 are switched.

The outputs of the three C0D2.6.8 are distributed to two outputs: one that is returned to the input in the output circuit 3, 6.9, and the other that outputs it. Signals R-1 to R-3 are added to each of the signals R-1 to R-3, and these signals are controlled to be output only when they are at a high level.

The output signals from the three buffers 3 and 6.9 are added in an adder circuit 10, and then passed through a low-nosis filter (LDF) 11 that removes the COD clock component, and then converted into a second horizontal scanning method. output terminal Xou as a signal of
t, output to Yout.

Effects of the Invention As described above, in the present invention, by transferring the COD and changing the lock, it is used as a time compression element and at the same time has the function of storing by stopping the clock, thereby allowing two different scanning methods to be used. A simple conversion circuit has become OJ functional.

To convert an NTSC system signal to a high-definition television system, since the vertical frequencies are the same, it is sufficient to convert the horizontal frequency, and according to the present invention, a high-definition television receiver can convert NTSC signals to
You can view C-type images.

Since format conversion can be performed with a relatively simple circuit configuration as described above, it can also be incorporated into general household television receivers.

[Brief explanation of drawings]

1 and 2 are waveform diagrams illustrating the operation of a scanning line number conversion device according to an embodiment of the present invention, and FIG. 3 is a block diagram of the same device. 1.4.7...Enter Kasisochi, 2,5.8...
... Addition circuit, 12 ... Conversion circuit, 13.14
Oscillation circuit, 15...Switching circuit, 16...
・Synchronous control circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person
1 Figure 2

Claims (1)

[Claims] Two types of scanning methods have the same vertical frequency but different horizontal frequencies, and the horizontal scanning period of the first scanning method is an integer multiple of the horizontal scanning period of the second scanning method, and the horizontal scanning period of the second scanning method is different from that of the second scanning method. Two types of television signals having a time difference equal to or less than the scanning period are received, and the first . Using second and third charge transfer devices in parallel, a television signal of a first scanning method is transmitted to the first to third charge transfer devices for a first horizontal scanning period using a write clock of a first frequency. Writing is held until the start of the second horizontal scanning period, and the scanning line is transferred from the first scanning method to the second scanning method by repeatedly reading n times using the read clock of the second frequency during the second horizontal scanning period. Scanning line number conversion device 0 characterized by converting numbers