JPS6244464B2 - - Google Patents

Description

[Detailed Description of the Invention] As a correction circuit for left and right pink tension distortion,
There is something like the one shown in Figure 1. That is, between the input coil 1A of the flyback transformer 1 and the ground, the collector-emitter of the switching transistor 2, the damper diode 3, and the resonance capacitor 4 are connected in parallel.
Horizontal deflection coil 5 and S-shaped correction capacitor 6
and the auxiliary coil 11 are connected in series. Further, a series circuit between a large capacity capacitor 12 and an anode/cathode of a thyristor 13 is connected in parallel to the coil 11, and a diode 14 is connected in parallel to the thyristor 13.

A horizontal pulse is then supplied to the base of the transistor 2 from the horizontal oscillation circuit 16 . moreover,
The horizontal feedback pulse Ph obtained from the feedback coil 1C of the transformer 1 is supplied to the phase modulation circuit 17, and the vertical parabolic voltage Vp is supplied from the vertical deflection circuit 18.
is supplied to the modulation circuit 17 as a modulation input, and its modulation output is supplied to the gate of the thyristor 13. In this case, the modulation circuit 17 operates as a control circuit for the thyristor 13, and a horizontal control pulse, which is the control output thereof, is supplied to the gate of the thyristor 13.

Further, a diode 7 is connected to the high voltage coil 1B of the transformer 1, and a DC voltage HV is supplied to a picture tube (not shown). Furthermore, a resistor 8 and a capacitor 9 are connected to the ground side of the coil 1B.
ABL voltage is extracted.

In such a configuration, for the sake of simplicity, if the connection point between the capacitor 6 and the coil 11 is grounded, this is the same as a general horizontal deflection circuit, so the following operation is performed. That is,
By means of horizontal pulses from the oscillator circuit 16, the period
At T ₁ , transistor 2 is turned on as shown in Figure 2A, so the voltage Vf at its collector becomes
As shown in Figure B, it is 0. However, this period
At T ₁ , the voltage charged in the capacitor 6 is discharged through the line from the capacitor 6 to the deflection coil 5 to the transistor 2 to the capacitor 6, and the voltage in the deflection coil 5 is as shown by the solid line in FIG. 2D.
The current Id gradually increases in the opposite direction. At this time, electromagnetic energy is accumulated in the coil 5 as the current Id flows through the coil 5.

Then, in period T ₂ , transistor 2 is turned off, so the energy accumulated in coil 5 during period T ₁ causes current Id to flow in the line from coil 5 → capacitor 4 → capacitor 6 → coil 5, and this The current Id gradually decreases. Further, the capacitor 4 is charged by this current Id, and the voltage Vf increases.

Then, in period _T3 , the energy stored in the coil 5 becomes 0, so Id=0, but this time, the voltage charged in the capacitor 4 becomes
Vf is capacitor 4 → coil 5 → capacitor 6
→ Discharge through the line of capacitor 4, and the voltage
As Vf decreases, current Id increases.

Then, in period T ₄ , the energy accumulated by the current Id flowing through the coil 5 during period T ₃ causes the coil 5 → capacitor 6 → diode 3
→Current Id flows through the coil 5 line.

Therefore, a sawtooth wave current Id as shown by the solid line in FIG. 2D flows through the deflection coil 5, with the operation of the period T ₁ to _{T 4} being one cycle, so that horizontal deflection is performed.

In this case, the circuit of FIG.
3 and 14 are connected, the pink tension distortion is corrected as follows. That is, as shown by the solid line in FIG. 2C, if the voltage Vg rises at a relatively early point in the period _T3 within the horizontal flyback period, the thyristor 13 is on for most of the period _T3 . , when the capacitor 4 discharges during the period _T3 , most of its energy is supplied to the deflection coil 5, and therefore the amplitude (level) of the horizontal deflection current Id increases as shown by the solid line in FIG. 2D.

In addition, as shown by the broken line in FIG. 2C, the voltage Vg
rises at a relatively late point in the period _T3 , the thyristor 13 is off for most of the period _T3 , so when the capacitor 4 discharges during the period _T3 , that energy is also supplied to the coil 11. Therefore, the energy supplied to the deflection coil 5 is reduced. Therefore, the horizontal deflection current Id is shown in Fig. 2D.
The amplitude decreases as shown by the broken line.

Therefore, if the rising phase of voltage Vg is changed, the amplitude of horizontal deflection current Id will change accordingly.

On the other hand, in the modulation circuit 17, a sawtooth wave current Vh is formed from the horizontal feedback pulse Ph in synchronization with the horizontal feedback pulse Ph, and this voltage Vh is superimposed on the vertical parabolic wave Vp to form a voltage Vp as shown in FIG. 3A. A superimposed voltage Va with Vh is formed, and this voltage Va is sliced at the level Vs. Therefore, as shown on the left side of FIG. 3B, at the top and bottom of the screen, the voltage Vh is lower than the slice level Vs.
As shown on the left side of Fig. 3C and D, a voltage Vg with a slow rising phase is obtained, and in the center of the screen, as shown on the right side of Fig. 3B, a voltage Vg is obtained with respect to the slice level Vs. Since Vh becomes high, the third
As shown on the right side of Figures C and D, the rising phase of the voltage Vg becomes earlier.

Therefore, the amplitude of the horizontal deflection current Id becomes small at the top and bottom of the screen, and the amplitude of the current Id becomes large at the center of the screen, so that pink distortion distortion on the left and right sides of the screen is corrected.

However, in such a correction circuit for pink tension distortion, there is a risk that X-rays will be generated due to the high voltage HV in the event of an abnormality. In other words, if the voltage Vg rises slowly as shown by the broken line in Figure 2C,
Since the thyristor 13 is off during most of the period T ₃ , the width of the pulse voltage Vf (period T ₂ + T ₃ ) is determined by the resonance frequency of the capacitor 4 and the coils 5 and 11, and therefore the pulse voltage Vf Since the width of is relatively wide, its peak value is relatively low. However, as shown by the solid line in FIG. _2C , when the voltage Vg rises quickly, the pulse voltage
The width of Vf is determined by the resonance frequency of capacitor 4 and coil 5, and therefore, the width is relatively narrow, so the peak value of voltage Vf becomes high.

Therefore, if the phase modulation of the pulse Ph by the voltage Vp becomes overmodulated due to fluctuations in the commercial AC voltage or changes over time, the voltage Vg will rise very early in the period _T3 , and as a result, the pulse voltage Vf will increase. The peak value of is abnormally high, and the high-pressure HV becomes higher than necessary, resulting in the generation of X-rays exceeding the permissible level.

Of course, in this case, due to overmodulation, the pink distortion distortion is not corrected correctly, so the playback screen is distorted, but for example, in the case of aging, the change will gradually occur. A large amount of X-rays may be generated without noticing the distortion on the playback screen. Furthermore, when a service person is adjusting the correction circuit for parts replacement or maintenance due to a failure, overmodulation may occur and the service person may be exposed to a large amount of X-rays.

This invention attempts to solve these problems.

An example of this will be explained below. Note that the following example is also a case in which the pink distortion distortion can be appropriately corrected even if the brightness of the screen changes.

That is, when the screen is relatively dark and the load current of transformer 1 is relatively small, the flyback pulse voltage Vf is a half-cycle sine wave as shown by the thick line in FIG. When the target voltage is bright and the load current of the transformer 1 is relatively large, the waveform of the pulse voltage Vf is distorted as shown by the thin line in FIG. 4B due to changes in the resonant frequency of the transformer 1.

Therefore, as shown by the solid line in FIG. 4A, if voltage Vg rises at an early time point _t1 corresponding to the center of the screen, the level of voltage Vf at time point _t1 when the screen is bright is Since the level of the voltage Vf at time t ₁ is smaller than that of the screen, as shown in Figure 5, at the center of the screen, the amplitude of the deflection current Id when it is bright (shown by a thin line) is the same as the deflection current when it is dark. The amplitude becomes smaller than the amplitude of Id (shown by the bold line), and the correction of the pink tension distortion becomes insufficient.

In addition, if the voltage Vg rises at a late time point _t2 corresponding to the top and bottom of the screen, the level of the voltage Vf at time _t2 when the screen is bright is the same as the voltage Vf at time _t2 when the screen is dark. Therefore, as shown in Figure 5, at the top and bottom of the screen, the amplitude of the deflection current Id when it is bright is larger than the amplitude of the deflection current Id when it is dark, which corrects the pink distortion distortion. becomes too much.

In the example below, the pink tension distortion is also appropriately corrected for this luminance change.

In FIG. 6, a vertical deflection coil 21, an integrating capacitor 22, and a feedback resistor 23 are connected to the vertical deflection circuit 18, and a vertical deflection current is supplied to the deflection coil 21. Vertical sawtooth voltage at the connection point with 23
Vv is taken out and this voltage Vv is fed back to the deflection circuit 18.

A differential amplifier 30 is configured by the transistors 31 and 32, and the connection point between the coil 21 and the capacitor 22 is connected to the base of the transistor 32 through the resistors 34 and 35. The connection point with the transistor 31 is connected to the base of the transistor 31 through resistors 37 and 38. Furthermore, a connection point between resistors 34 and 35 is connected to resistor 38 through a diode 39.

Also, a resistor 4 is connected between the power supply terminal 41 and the ground.
2, 43 and capacitors 44, 45 are connected in series, and the connection point between the capacitors 44 and 45 is connected to the base of the transistor 32, and the resistor 4
The collector and emitter of a transistor 46 are connected between the connection point of transistors 2 and 43 and the ground.

Furthermore, coil 1C of flyback transformer 1
is connected to the base of transistor 46 through delay circuit 50. Also, coil 1B of transformer 1
The connection point between resistor 8 and capacitor 9 is connected through filter 52 and further through resistor 53 to the connection point between resistor 43 and capacitor 44, and through resistor 54 to the base of transistor 31.

Further, the collector of the transistor 32 is connected to the thyristor 1 through a transistor 60 whose emitter is grounded.
Connected to gate 3.

Further, a transistor 61 whose emitter is grounded is provided, and the coil 1C of the transformer 1 is connected to the differential circuit 62.
It is connected to the base of transistor 61 through resistor 64, and its collector is connected to the base of transistor 31 through resistor 64. Note that the capacitor 63 is for delay.

According to such a configuration, the vertical parabolic voltage Vp is applied to the connection point between the deflection coil 21 and the capacitor 22.
is obtained, and this voltage Vp is supplied to the base of transistor 32 through resistors 34 and 35.

In addition, in the coil 1C of the transformer 1,
A horizontal feedback pulse Ph is obtained as shown in FIG. Therefore, transistor 46 is turned off every pulse Pd, as shown in FIG. 7C. During the period when the transistor 46 is off, the capacitor 45 is charged mainly through the power supply terminal 41 → resistor 42 → resistor 43 → capacitor 44 → capacitor 45 → ground line, and during the period when the transistor 46 is on, Mainly, capacitor 4
The capacitor 45 is discharged through the line 5→capacitor 44→resistor 43→transistor 46→capacitor 45. Therefore, a sawtooth wave voltage Vh synchronized with the pulse Pd is obtained at the capacitor 45, as shown in FIG. 7D.

Since this voltage Vh is supplied to the base of the transistor 32, and the vertical parabolic voltage Vp is also supplied to the base of the transistor 32, the transistor 32 is equivalently supplied with the vertical parabolic voltage Vp and the horizontal sawtooth voltage Vp. A superimposed voltage Va (Fig. 3A) with the wave voltage Vh is supplied,
Its collector has a phase modulation voltage shown in Figure 7E.
Vg is obtained.

In this case, the capacitor 22 is connected to the feedback resistor 23.
is connected, the parabolic voltage Vp includes a vertical sawtooth voltage component, but the vertical sawtooth voltage Vv obtained at the resistor 23 is supplied to the transistor 31 through the resistors 37 and 38. Therefore, the vertical sawtooth voltage component included in the parabolic voltage Vp is canceled out. Also, at this time, a part of the parabolic voltage Vp is sliced by the diode 39 and supplied to the transistor 32, and the waveform of the parabolic voltage Vp is corrected.

Further, by varying the variable resistor 89, the DC level of the base voltage of the transistor 31 is changed, so that the rising phase of the voltage Vg can be adjusted.

Then, the voltage Vg obtained at the transistor 32
is supplied to the transistor 61 and inverted to the voltage Vg shown in FIG. 7F, and this voltage Vg is supplied to the gate of the thyristor 13 as a horizontal control pulse, so that the horizontal pincushion distortion is corrected.

In this case, according to the present invention, the phase of the rise of the horizontal control pulse voltage Vg from the modulation circuit 14, that is, the control circuit, is the same as that of the transistor 6.
Since it is limited by 0, overmodulation will not occur. That is, the falling portion of the horizontal feedback pulse Ph obtained by the coil 1C of the transformer 1 is supplied to the differentiating circuit 62 and differentiated, and the waveform is blunted by the capacitor 63 to form a wide differentiated pulse, as shown in FIG. The pulse Pb shown in G is supplied to the base of the transistor 61. Therefore, the transistor 61 is turned off during the period T ₂ and the following predetermined period τ, as shown in FIG. 7H, and is turned on during the other periods.

The differential waveform of the horizontal feedback pulse Ph is a so-called second-order differential waveform, with the first half convexing downward and the second half convexing upward; however, in this invention, the downward convex portion of the first half is important, so In Fig. 7G, the upper convex portion in the latter half is omitted.

Then, during the period when the transistor 61 is on,
The voltage Vg is formed as described above by selecting the values of the resistors 33 and 64 in advance, but during the periods T ₂ and τ when the transistor 61 is off, the bias voltage is divided by the resistor 64. Since there is no operation, transistor 31 is turned on.
Therefore, as shown in FIG. 7H, the transistor 32 is turned off during the period T ₂ , τ, so the voltage Vg obtained at the collector of the transistor 32 is
T ₂ and τ are always "1", so the voltage Vg supplied to the thyristor 13 does not rise during the period τ.

If the voltage Vg does not rise during the period τ, the high voltage HV will not rise abnormally, and therefore the generation of X-rays can be suppressed to below a permissible value.

Furthermore, even if the level of high-voltage HV changes depending on the brightness of the screen, appropriate correction of pink tension distortion is performed. That is, when the charging current of the capacitor 45 flows through the resistors 42 and 43, a part of the charging current is shunted through the resistor 53.
However, if the screen is relatively dark, the ABL voltage
When Vy becomes a relatively small negative voltage, the filter 5
Since the potential at the output end of the resistor 2 is a relatively small negative potential, the shunt current flowing through the resistor 53 is small.
Therefore, since the charging current to the capacitor 45 is large, the horizontal sawtooth wave voltage obtained at the capacitor 45
The amplitude of Vh increases. Therefore, as explained in FIG. 4, the voltage Vg is obtained in the relationship shown by the thick solid line and broken line in FIG.

Furthermore, when the screen is relatively bright, the ABL voltage Vy becomes a relatively large negative voltage, and the potential at the output end of the filter 52 becomes a relatively large negative potential, so that a shunt current flows through the resistor 53. increases, and therefore the charging current to the capacitor 45 decreases, so the amplitude of the horizontal sawtooth wave voltage Vh obtained across the capacitor 45 decreases as shown by the thin solid and broken lines in FIG. Therefore, at the center of the screen, the rising phase of voltage Vg advances to time t ₁₁ , and the level of voltage Vf at time t ₁₁ when the screen is bright is equal to the voltage at time t ₁ when it is dark.
Since it becomes equal to (or slightly larger than) the level of Vf, the amplitude of the deflection current Id also becomes equal.

Moreover, at the top and bottom of the screen, the rising phase of voltage Vf is delayed until time t ₁₂ , and the level of voltage Vf at time t ₁₂ when the screen is bright is equal to the level of voltage Vf at time t ₂ when it is dark. (or slightly larger), so the amplitudes of the deflection currents Id also become equal.

Therefore, even if the brightness of the screen changes, an appropriate amount of pink distortion distortion can be corrected.

Also, when the high voltage HV changes due to changes in screen brightness, the horizontal deflection width changes, but the ABL voltage
Vy is supplied to transistor 31 through filter 52 and resistor 54, thereby causing the level
Since Vs is changed, the amplitude of the deflection current Id is changed, and changes in the horizontal deflection width due to high voltage fluctuations are corrected.

As described above, according to this invention, the period
By turning off the transistor 61 at T ₂ , τ, the phase of the voltage Vg is restricted from advancing more than necessary, so that generation of X-rays can be suppressed.

Note that in the above description, the phase advance of the voltage Vg is limited by supplying the pulse Pb to the transistor 61, but by supplying the pulse Pb to the transistor 32,
Alternatively, it may be limited by supplying it to the emitters of the transistors 31 and 32. Further, it may be supplied to the signal path of the voltage Vg between the transistor 32 and the thyristor 13.

This invention was originally filed by the applicant in a patent application filed in 1983.
It can be applied in exactly the same way to the correction circuit shown in FIG. 9 proposed in No. 44996 and Japanese Patent Application No. 53-44997. That is, in the circuit of FIG. 9, the damper diode 3 connects the capacitor 12 and the thyristor 13.
and the collector of the transistor 2, and correction of pink tension distortion is performed in the same manner as in FIG. 1, as detailed in the above-mentioned earlier application.

[Brief explanation of the drawing]

FIG. 1 is a connection diagram for explaining this invention, FIGS. 2 to 5 are diagrams for explaining it, FIG. 6 is a connection diagram of an example of this invention, and FIGS. 7 and 8 are diagrams for explaining the same. A diagram for explanation, FIG. 9 is a connection diagram of another example. 1 is a flyback transformer, 5 is a horizontal deflection coil, 16 is a horizontal oscillation circuit, and 17 is a modulation circuit.

Claims (1)

[Claims] 1 A series circuit consisting of a horizontal deflection coil, a first capacitor, and another coil, a second capacitor for resonance, and a damper diode are connected in parallel to the first switching element for horizontal output, and the other A series circuit of a third capacitor and a second switching element is connected in parallel with the coil, and phase modulates the horizontal pulse with a vertical parabolic wave to generate a horizontal control pulse having a phase corresponding to the level of the vertical parabolic wave. A control circuit is provided, and the horizontal control pulse is supplied to the second switching element to turn on the second switching element at different positions depending on the level of the vertical parabolic wave within the horizontal flyback period, thereby suppressing the pink tension distortion. In addition to making the correction, a circuit for limiting the phase of the horizontal control pulse is provided in the control circuit so that the point at which the second switching element starts to turn on is limited to a later half of the peak position of the horizontal flyback pulse. Correction circuit for pink tension distortion.