JPS59160379A - Horizontal amplitude controller - Google Patents

Abstract

PURPOSE:To prevent the generation of ringing at the upper part of a video screen by eliminating the transient response of a deflection system right after the 1st horizontal scan of one field share is started. CONSTITUTION:When a control signal held in a vertical blanking period TVb/k varies in level, a control signal correcting circuit 30 supplies a correcting signal PS1 for one vertical scanning period Tv.scn which has an amplitude corresponding to a voltage difference DELTAV between a vertical blanking end point t2 of time and the 1st horizontal scanning start point t3 of time of every field to a horizontal deflecting circuit 20. Consequently, a deflecting current which is amplitude- modulated by said RS1 is supplied to a deflecting coil by a horizontal deflecting circuit 20 to deflect an electron beam EB horizontally. Then, the distortion component on the screen 29 corrected by said RS1 is detected by a photodetector 27 in the period Tv.scn, and a control signal for controlling the distortion component is supplied to the horizontal deflecting circuit 20 by a horizontal amplitude control circuit 28 on the basis of the photodetection result.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a horizontal amplitude control device for correcting distortion in the horizontal deflection of an electron beam, and the present invention relates to a horizontal amplitude control device for correcting distortion in the horizontal deflection of an electron beam. By comparing the signal levels at the start time, that is, at the start time of the first horizontal scan for one field, and supplying a correction signal corresponding to the difference to the deflection system together with the above control signal, the vertical set meal start time is determined. This was done in order to prevent the occurrence of the transient response of the deflection system mentioned above.

<Prior art and its problems> In general, a telephotography receiver scans the fluorescent surface 2 of the fluorine tube 1 as shown in FIG. 1 (electron beam E B emitted from the electron gun 11 as shown) A predetermined image 3 is projected onto the fluorescent surface 2.

That is, the electron beam EB emitted from the electron gun 11 scans horizontally (point a = point b, point C = point d.

) and horizontal return line (point b = point C, point 6 - point ○, ...
) is repeated to reach the 0 point (from this point, an image for the field is projected. Then, the Kameko beam EB that has reached the 0 point is again vertically deflected to the 0 point at the top of the fluorescent surface 2, and the above-mentioned Repeat this action to project the next field's worth of images.

As mentioned above, the period from point a to point n for the electron beam EB is called the vertical scanning period Tv, scn.
The period from point to point 0 is the vertical retrace period 'l:'
It is called v, blk.

Incidentally, since the moving speed of the electron beam EB becomes faster as it approaches the ends of the fluorescent surface 2, the amount of deflection of the electron beam EB increases at the four corners of the fluorescent surface 2, causing so-called left-right pincushion distortion in the image 3. .

Therefore, in order to correct the distortion of the image 2, a second
A horizontal amplitude control device 5 as shown in the figure was used.

This horizontal amplitude control device 5 is installed vertically on the side of the effective screen 4 of the cathode ray tube, and has an index 6 having a length e that can cover the length of the effective screen 4 in the vertical direction, and an electronic A photodetector 7 detects the specially emitted light through which the beams E and B have passed, and the Intex 6 is detected from the horizontal scanning start time t3 for each horizontal scanning of the electron beam EB based on the detection signal from the photodetector 7. It has a horizontal amplitude control circuit 8 which outputs a parabolic control signal corresponding to the left and right pincushion distortion of the image 2 in accordance with the size of the time interval in passing.

3C outputted from the horizontal amplitude control circuit 8.
The parabolic ff control signal S1 shown in A,] is supplied to the horizontal deflection circuit 9, and thereby the magnitude of the deflection current supplied from the horizontal deflection circuit 9 to the horizontal deflection coil 10 is made to correspond to the control signal Sl. The amplitude is modulated in a parabolic manner.

As a result, the distortion-corrected deflection current is supplied to the horizontal deflection coil 10, so that the distortion of the image 3 is corrected.

By the way, the control signal S1 is controlled by the electron beam E as described above.
It is created by detecting the point in time when B passes above index 6. Therefore, the above electron beam EB has index 6
If it does not pass through, then vertical retrace period Tv,b
Ik control signal 81 is not generated. Therefore, conventionally, a method has been adopted in which the level of the side leg signal Sl at the vertical scanning end time t is held during the vertical retrace interval blk.

However, during the vertical retrace periods Tv and blk, there were cases where the level of the control signal Sl changed due to natural discharge of the capacitor, as shown in FIG. 3 (B).

In this case, between the signal level at the vertical retrace end point 12 and the signal level at the start point of the vertical scanning period TV-5C11, that is, the first horizontal scanning start point T3 for one field. Since a gap of more than a certain level occurs in Figure 3 [
13], a transient response occurs in the deflection system immediately after the horizontal scanning start time t3.

This transient response also affects the deflection coil current supplied to the deflection coil 10, causing ringing in the upper part of the image 3 projected on the fluorescent surface 2. 2 distortion may occur.

In that case as well, a control signal S3 as shown in FIG. 3 [C1] corresponding to the same minute as in the case described above is generated.

Also in this case, a gap of more than a certain level may occur in the signal level between the end time t2 of the vertical retrace period 'pv,))Ik and the first horizontal scanning start time t3, and this is different from the case described above. Similarly, there was a risk that ringing would occur at the top of the image.

<Object of the Invention> The present invention has been made in view of the above-mentioned circumstances, and eliminates the ringing at the top of the video screen by eliminating the transient response of the deflection system immediately after the start of the first horizontal scan for one field. The purpose is to prevent the occurrence of

<Summary of the Invention> In order to achieve the above object, the present invention comprises an index vertically arranged on at least one side of the left and right sides of the effective screen of a fluoroun tube, and a heel detection detector for detecting when an electron beam passes over the index. - a horizontal amplitude control circuit that outputs a control signal according to the time interval from the start of horizontal scanning to the point in time when the electronic beam passes over the index in each horizontal scanning period; and a signal at the end of the vertical retrace line of the control signal. A control signal correction circuit is provided which compares the level with the signal level at the start of vertical scanning and outputs a correction signal according to the difference, and performs feedback control of the horizontal deflection circuit using the control signal and the correction signal. The gist is:

<Example> Hereinafter, an example according to the present invention will be explained in detail using FIGS. 4 to 9.

FIG. 4 is a block diagram showing the electrical configuration of a deflection system to which the horizontal amplitude control device according to the present invention is applied.

Reference numeral 20 denotes a horizontal deflection circuit, which deflects the electron beam E B emitted from the electron gun 22 in the horizontal direction at a predetermined period on the fluorescent surface 24 of the fluorine tube 23 in response to a horizontal drive signal supplied through the input terminal 21. A deflection current for this purpose is supplied to a horizontal deflection coil 25 provided in the fluorine tube 23.

26 is an index, and in this embodiment, the tex 26 is placed on the top, and when the electron beam EB scans over this index 26, a sufficient amount of light is generated. Note that the index 26 has a length l that can cover the length in the vertical direction to the effective screen 27.

And the light emitted by Intex 26 is fu.

It is detected by a photodetector 27 which is a beam detection output stage provided outside one of the lauan tubes 23, and the photodetector 27 sends a detection signal indicating the point in time when the electron beam EB passes over the above-mentioned intex 26 to a horizontal amplitude control circuit. 28.

This horizontal amplitude control circuit 28 uses the detection signal to generate a control signal S4 as shown in FIG. Appear.

The signal level of the control signal S4 is at the horizontal scanning start time t3 of the electron beam EB and at the index passing time.

Therefore, the waveform of the control signal S4 has a parabolic shape corresponding to the pincushion distortion of the screen 29 when the control signal s1 is not supplied to the horizontal deflection circuit 2o, as shown in FIG. 8A.

The parabolic control signal S4 is then supplied to the horizontal deflection circuit 20 and the control signal correction circuit 30.

The control signal correction circuit 30 is shown in FIG. 8 [B] and FIG. 9 [
A, signal level of control signal S5, 87 shown in vertical retrace line end time t2 and vertical scanning period Tv, start time of scn, first horizontal scanning start time t3 of Zunawa 1 field 1-minute Figure 7 [B
A correction signal tt that produces a sawtooth waveform as shown in
S is supplied to the horizontal deflection circuit 20.

FIG. 6 is a circuit diagram showing a specific configuration of the control signal correction circuit 30. The control signal correction circuit 30 is composed of a Hanosor amplifier 32, a sample bold circuit 33, and an integrating circuit 40.

The fli control signal S5 is input to this control signal correction circuit 30 via an input terminal 31. The supplied control signal S5 is then supplied to the sampling switch 34 of the sample hold circuit 33 via the hasher amplifier 32.

The sample hold circuit 33 includes the sampling switch 34, an amplifier 35, and a hold capacitor 3.
b, 37 etc. The sampling link switch 34 supplies the voltage ■l of the control signal S5 at the first horizontal scanning start time t3 for each one film 1 to one of the capacitors 36, and also supplies the control signal S1 at the vertical blanking end time t2 to one of the capacitors 36. The voltage 2 of S5 is switched to the other capacitor 37 at the appropriate timing. In addition,
Each of the above points t2. At times other than t3, the control signal S5 is not supplied to each of the capacitors 36 and 37.

The one capacitor 36 supplies the held voltage V+ of the control signal S5 at the horizontal scanning start time t3 to the inverting input terminal of the amplifier 35 via the resistor 38. Further, the other capacitor 37 supplies the similarly held voltage v2 of the 'ff1lJH signal S5 at the vertical blanking end time t2 to the non-inverting input terminal of the amplifier 35.

The output of the amplifier 35 is supplied to the inverting input terminal via a resistor 39 to form a return loop.

As a result, the sample and hold circuit 33 is activated as shown in FIG.
A], the voltage difference △V: IVI of the control signal S5 at the horizontal scanning start time t3 (!: Vertical retrace end time t2
It outputs the Zambreholt output signal S HS having an amplitude corresponding to V21, and supplies the signal SH8 to the integrating circuit 40. and the supplied sample-and-hold output signal S
HS is connected to the operational amplifier 4 of the integrating circuit 40 via a resistor 41.
It is supplied to the inverting input terminal of No. 2.

Further, the non-inverting input terminal of this operational amplifier 42 is grounded, and its output is supplied to the above-mentioned inverting input terminal via a capacitor 43 to form a return loop.

In addition, a recent switch 44 which is reset by the vertical retrace line is connected to the return loop in parallel with the capacitor 43.

As a result, the integrating circuit 40 converts the sawtooth wave having an amplitude corresponding to the voltage difference Δ■ and a wavelength corresponding to the vertical scanning period Tv, scn into the correction signals R, S, as shown in FIG. Output as .

The correction signals R and S are then supplied to the horizontal deflection circuit 20 via the output terminal 45 as output signals of the irl 111 signal correction circuit 30.

Next, the specific operation of the deflection system configured as described above will be explained.

First, as shown in FIG. 8 [A], the vertical retrace period Tv,
There may be cases where the level of the Hall 1 control signal changes due to natural discharge of the capacitor or the like between b and lk.

In this case, as described above, the control signal correction circuit 30 generates an amplitude corresponding to the voltage difference ΔV between the vertical retrace end time t2 and the first horizontal scan start time t3 for each field during one vertical scanning period 'll'. v, ,c, 1 minute correction signal R8, is supplied to the horizontal deflection circuit 20.

As a result, the horizontal deflection circuit 20 supplies a deflection current whose amplitude is modulated by the correction signal 1tSl to the deflection coil 24, thereby horizontally deflecting the electron beam gB.

Then, from then on, during that vertical scanning period TV, scn.
= 2rI of the screen 29 corrected by the correction signal R8l Control signal S6 as shown in FIG.
is supplied to the horizontal deflection circuit 20.

Therefore, as described above, even if the signal level of the control signal S5 changes by a certain amount Δ■ during the vertical retrace period Tv, blk, the return control of the horizontal deflection circuit 20 is performed by the control signal and the correction signal. By this, the vertical scanning period '1''V, 5
The signal level at the start time t3 of C11 can be made equal to the signal level at the end time t2 of the vertical retrace line, and the deflection system when moving from the vertical retrace end time t2 to the start time t3 of the vertical scanning period '17v, scn. It is possible to prevent the occurrence of a transient response, and it is also possible to prevent the occurrence of linking at the top of the image.

In addition, there may be cases where the television receiver is moved or the like.

In this case, as in the case described above, first, the correction signal R82 for one vertical scanning period Tv, scn is supplied to the horizontal deflection circuit 20, and as a result, the correction signal R82 shown in FIG. A control signal S8 as shown in [B] is supplied to the horizontal deflection circuit 20 to correct the -vertical scanning periods Tv and scn.

In this case, the starting time t3 between vertical scans 191
In order to correct the positive portion due to the earth's magnetic field using the sawtooth correction signal R82 having an amplitude corresponding to the change in signal level ΔV between the vertical retrace end point t2 and the vertical retrace end time t2, the vertical retrace period ζ is used as in the previous case. Vertical scanning period Tv, scn from Tv, blk
It is possible to prevent the occurrence of a transient response of the deflection system when moving to the image, and it is possible to prevent the occurrence of linking at the upper part of the image.

<Effects of the Invention> As is clear from the above description, the present invention compares the signal level of the control signal at the end of vertical blanking with the signal level at the start of vertical scanning, and outputs a correction signal according to the difference. In particular, a control signal correction circuit is provided to supply the correction signal to the horizontal deflection circuit together with the control signal, thereby improving the feedback loop of the horizontal deflection circuit. Even if a certain degree of difference occurs between the signal levels at the end of vertical retrace and the start of vertical scanning by carrying out step A, this will prevent a transient response of the deflection system due to the difference and prevent ringing from occurring at the top of the video screen. In addition to being able to correct the distortion of the video screen correctly, it becomes difficult to correct.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of a fluorine tube, and FIG. 2 is a block diagram showing the electrical configuration of a conventional deflection system. Figure 3 is a waveform diagram of the control signal output from the horizontal amplitude control circuit shown in Figure 2. Figure 3 [A] is a normal state, Figure 3 (I3)
3 shows a state in which the control signal changes during the vertical retrace period, and FIG. 3 shows a state in which the control signal changes due to changes in geomagnetism, etc. FIG. FIG. 5 is a schematic front view of a fluorown tube to which the present invention is applied, and FIG. 6 is a circuit diagram of the control signal correction circuit in FIG. 4. FIG. 7 is a waveform diagram of the power signal of the control signal correction circuit of the control signal correction circuit in FIG. 6;
The output signal and FIG. 7(B) show the correction signal, respectively. Figure 8 is a waveform diagram showing the (TFI signal) for performing amplitude modulation of the deflection current. Waveform diagram of the control signal in a conventional deflection system when the level changes,
FIG. 8 [q is a waveform diagram of the signals of the deflection system shown in FIG. ) is a waveform diagram of the control signal in the conventional deflection system when the control signal changes due to changes in geomagnetism, etc., and FIG. 9(B) is a waveform diagram of the signal in the deflection system shown in FIG. 4. 20.・・・・・・Horizontal deflection circuit 22・・・・・・Front tube Shiro・・・・・・Inch Nox 27・・・・・・
...Photodetector 30...... Control signal correction circuit and Figure 2 499 Figure 6 Figure 7 Figure 8 Figure 9

Claims (1)

[Claims] Is the effective screen of a Fraun tube less on the left or right than on one side? - A detection stage for detecting when the electron beam has passed over the index; A horizontal amplitude control device that outputs a control signal according to a time interval, compares the signal level of the control signal at the end of the vertical retrace line with the signal level at the start of the vertical set meal, and outputs a correction signal according to the difference. 1. A horizontal amplitude control device comprising a control signal correction circuit for controlling a horizontal deflection circuit using the 111 signal and the correction signal.