JPS6243390B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vertical line distortion correction circuit that detects the amount of distortion in a vertical line and performs correction using a correction signal corresponding to the detected amount of distortion.

An example of a conventional vertical line distortion correction circuit is shown in FIG.
This will be explained below. The vertical output signal input from the signal input terminal 1 is passed through the DC blocking capacitor 2 and the integrating circuit (resistors 5, 9, capacitor 3,
4) and is converted into a distortion correction signal (parabolic waveform). This signal is biased by resistors 6 and 7, amplified by a transistor 10 having a resistor 8 connected between its emitter and ground, and applied to a vertical coil 11v of a correction transformer 11. 12 is a power terminal. The correction transformer 11 is a vertical coil 1
If the current flowing through the vertical coil 11v is small, the inductance of the horizontal coil 11h connected in series with the horizontal deflection coil is increased, and if the current flowing through the vertical coil 11v is large, the inductance of the horizontal coil 11h is increased. Reduce inductance. Therefore, vertical coil 1
If a parabolic current (a waveform in which the current is small at the beginning and end of the vertical scanning period and large in the middle) is applied to 1V, vertical line distortion can be substantially corrected. However, as described above, in the conventional technology, the distortion correction signal does not correspond accurately to the actual amount of distortion, and is approximated by a signal obtained by integrating the vertical output signal, so there is a drawback that some distortion remains even after correction. be.

SUMMARY OF THE INVENTION An object of the present invention is to provide a distortion correction circuit that eliminates the above-mentioned drawbacks of the prior art and can extremely reduce residual distortion by performing distortion correction according to each amount of distortion.

The key point of the present invention is to actually detect the amount of distortion of the vertical line,
By correcting vertical line distortion using a distortion correction signal corresponding to the amount of distortion, the amount of residual distortion can be significantly reduced compared to conventional distortion correction circuits.

The present invention will be described in detail below with reference to the drawings.
FIG. 2 is a block diagram showing one embodiment of the present invention.
It mainly consists of a time interval detector 15, a pulse width/amplitude converter 16, and an inversion circuit 17.
3 is a horizontal synchronizing signal input terminal, and 14 is an index signal input terminal indicating the beam position. FIG. 3 shows the relationship between the vertical line distortion shape 19 and the index stripe 18 for detecting the beam position. Figure 4 shows the positional relationship on the time axis of the horizontal synchronizing signal 22 and index signal 21 at a-a', b-b', and c-c' in Figure 3, and 1H indicates one horizontal period. . Figure 5 shows the output waveforms of the time interval detector 15 for a, b, and c in Figure 4, and is 1V.
indicates one vertical period. Also, Figure 6 shows the pulse width/
The output waveforms of the amplitude converter 16 are shown as a, b, and c in FIG.
This is what is shown.

Now, suppose that the vertical line distortion has a shape as shown by reference numeral 19 in FIG. It is sufficient to detect the phase difference with the index signal (electron beam scanning position detection signal) 21, that is, the time interval between the two, and repeat this during the vertical period. That is, for example, when the distortion amounts of the vertical lines at a-a', b-b', and c-c' in Fig. 3 are converted into time intervals, the output waveform 2 in Fig. 5 is obtained.
3 a, b, c, respectively τ ₁ and τ
₂ , _τ3 . Here the detected time interval τ
₁ , τ ₂ , and τ ₃ are generated by the pulse width/amplitude converter 16, as shown in FIGS. 6a, b, and c. It is converted into a correction signal. In the above, the amount of distortion is detected by 1
Although this detection has been described as being performed at the beginning of one horizontal scanning period, it may also be performed at the end of one horizontal scanning period, or both may be used in combination. Note that when the vertical line has a distorted shape as shown in Figure 3, the output waveform on the time axis will change as shown in Figures 4 and 5 due to the circuit configuration in Figure 2. The reason why this can be detected will be explained using FIG.

FIG. 7 shows only the vicinity of the left end of the screen shown in FIG. 3, and 25 indicates the left end of the screen. Assume that the electron beam is scanning from left to right.

19-1 to 19-4 indicate vertical lines when distortion correction is not performed (for example, a vertical line of a crosshatch signal), and the vertical line 19-1 is the leftmost signal, and for convenience, it is temporally connected to the horizontal synchronization signal. I think it matches.
18 is the index stripe shown in FIG.
parallel to - in other words, perpendicular to.

As is clear, in FIG. 7, the vertical line 19--
If lines 1 to 19-4 are set to be displayed at equal intervals on the screen in a non-distorted state, the scanning time between adjacent lines is the same. For example, when the horizontal scanning time of the effective screen is 51 μs and 18 vertical lines are displayed, the scanning time between adjacent lines is 3 μs.
becomes.

Therefore, the scanning lines a-a', b-b', c in FIG.
- If 19-1 is the horizontal synchronizing signal, the amount of distortion of the vertical line on -c' is equal to the interval between 19-1 and index stripe 18 on a-a' and c-c', and the vertical line distortion on a-a' and c-c' In one interval, the time difference is about 3
It is μs. Similarly, the amount of distortion on b-b′ is equal to the interval of 0.5 vertical lines, and the time difference is approximately 1.5μ.
It becomes s. Furthermore, at the top and bottom edges of the screen, the vertical lines are spaced 1.4 apart, resulting in a time difference of 4.2 μs.

As shown in FIGS. 4 and 5, the detected vertical line distortion amounts are calculated as shown in FIGS.
They are expressed as τ ₁ , τ ₂ , and τ ₃ on b-b' and c-c', respectively.

By inputting the distortion correction signal obtained in this way to the base of the transistor 10 of a circuit using a conventional correction transformer as shown in FIG. Line distortion correction can be performed. In the case of FIG. 2, since the polarity of the distortion correction signal is inverted, an inverting circuit 17 is added. Further, as the pulse width/amplitude converter, for example, a low pass filter or the like can be used.

As is clear from the above description, the present invention detects the amount of distortion of vertical lines for each scanning line, creates a distortion correction signal according to this amount of distortion, and performs distortion correction using this correction signal. Therefore, there is an advantage that residual distortion can be extremely reduced compared to the conventional method. In addition, in beam-indexed television receivers that can detect the scanning position of the electron beam, the color switching circuit for switching the color signal applied to the cathode in synchronization with the phosphor array has been simplified and performance improved. Additional effects can be expected.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of a conventional vertical line distortion correction circuit, FIG. 2 is a block diagram showing an embodiment of the present invention, and FIGS. 3 and 7 are diagrams showing a vertical line distortion shape and an index stripe. Figure 4 is a timing chart showing the relationship between the horizontal synchronization signal and index signal, Figure 5 is an example of the output waveform of the time interval detector, and Figure 6 is an example of the output waveform of the pulse width/amplitude converter. It is a diagram. 11...Correction transformer, 11v...Vertical coil, 1
1h...Horizontal coil, 13...Horizontal synchronization signal input terminal, 14...Index signal input terminal, 15...Time interval detector, 16...Pulse width/amplitude converter, 1
7...Inversion circuit.

Claims (1)

[Scope of Claims] 1. A vertical line distortion correction circuit for a television receiver using a cathode ray tube capable of detecting an electron beam scanning position, the circuit being arranged at at least one of the left and right ends of the cathode ray tube image plane. a horizontal synchronizing signal, a time interval of an index signal from the detecting body within one horizontal synchronization starting from the horizontal synchronizing signal, and an index signal from the detecting body and a horizontal synchronizing signal immediately thereafter; means for detecting at least one of the time intervals in each horizontal period, means for converting the time interval into a vertical line distortion correction signal, and a distortion correction circuit supplied with the vertical line distortion correction signal. A vertical line distortion correction circuit featuring: 2. The vertical line distortion correction circuit according to item 1, wherein the vertical line distortion correction signal is obtained by converting the time interval obtained for each horizontal period into an amplitude.