JPS59160378A - Horizontal output circuit for television receiver - Google Patents

Abstract

PURPOSE:To make distortion corrections by flowing all of the primary current of a flyback transformer which flows when a horizontal output transistor (TR) is on to a distortion correcting capacitor from a light load to a heavy load. CONSTITUTION:When the load is light (less DC component to flyback transformer 10), the primary current of the transformer 10 is fed back to a power source 11 in a damper period, but the capacitor (C) 15 which is charged by a power source 11 when a horizontal TR 17 is on and a distortion correction control TR 18 is off is still charged to apply a reverse bias to the distortion correction control TR 18. Consequently, all of the feedback current to the power source 11 flows to the C15 to pass through the C15 while discharging the C15. When the load is intermediate, the feedback current from the transformer 10 to the power source 11 is reduced, but all of the current flows through the C15 to reduce charges in the capacitor. When the load is heavy, no feedback current flows to the power source 11 and the current flows from the power source 11 to the transformer throughout a horizontal period. At this time, the control TR 18 turns on to charge the C15.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a horizontal output circuit for a television receiver.More specifically, the present invention relates to a horizontal output circuit for a television receiver. This invention relates to a horizontal output circuit equipped with a correction circuit.

[Prior art]

FIG. 1 is an explanatory diagram of a television screen on which screen distortion has not been corrected. In the figure, P indicates the screen, D indicates the dark part of the picture, and B indicates the bright part.

Generally, the brightness of the picture on a television screen varies depending on the broadcast content. When the picture is bright, a large beam current is required, which means that the high voltage load on the cathode ray tube increases, and the high voltage decreases.

Conversely, when the pattern is dark, the high voltage load decreases, but the high voltage increases.

As shown in Figure 1, when a bright pattern B is displayed at the center of the screen, the horizontal size of the bright part B increases as the rask moves vertically downward due to the high voltage drop in the cathode ray tube. It is known that the originally square portion B becomes distorted and becomes trapezoidal.

FIG. 2 is a circuit diagram showing a conventional horizontal output circuit equipped with a correction circuit for correcting screen distortion as described above.

In the figure, M is a horizontal oscillation circuit, 1 is a resistor, 2 is a capacitor, 3 is a horizontal excitation transformer, 4 is a horizontal excitation transistor, 5 is a horizontal output transistor, 6 is a damper diode, 7 is a resonant capacitor, and 8 is a horizontal deflection Yoke, 9 is a figure 8 correction capacitor, 10 is a flyback transformer, 1
1 is a power supply, 12 is a diode, 13 is a capacitor, 14
is a high voltage load, 15 is a capacitor, and 16 is a diode. A circuit portion Y indicated by a broken line corresponds to a distortion correction circuit.

FIG. 3 is a diagram of signal waveforms at various parts of the circuit in FIG. 2 when the raster is located in the central bright picture/pattern B in FIG. 1.

The circuit operation will be explained with reference to FIGS. 2 and 3.

Depending on the normal horizontal drive and output operation in a television receiver, the collector voltage of the horizontal drive transistor 4 is:
The waveform becomes as shown in FIG. 3 (■). Further, the base current of the horizontal output transistor 50 has a waveform as shown in ■, and the collector voltage has a waveform as shown in ◎. [F] Lightning current waveform, which shows the primary current waveform of the flybank transformer 10 under heavy load (when the tab pattern is bright).

Next, consider the current waveform flowing through the capacitor 15 in the distortion correction circuit Y, that is, the current waveform at the zero point.

During the ON period of the transistor 5, the current from the figure-8 correction capacitor 9 flows through the horizontal deflection coil 8, the output transistor 5, the ground, and the diode 16 to the capacitor 9. Further, the current from the power source 11 flows to the power source 11 through the primary side of the flyback transformer 10, the output transistor 5, and the ground. When the transistor 5 enters the OFF period, the continuous current of the deflection coil 8 flows through the resonant capacitor 7.
to charge. The continuous current from the primary coil of flyback transformer 1.0 is capacitor 7 and capacitor 15.
It flows through the ground to the ground and charges the converter f15e. This charging current waveform is shown by a zero point waveform.

Thereafter, the discharge current from the resonant capacitor 7 flows through the deflection yoke 8 and the stub correction capacitor 9. Of course, the i part is the primary side of the flyback transformer 1°, the power supply 11
, flows through capacitor 15 to resonant capacitor 7.

This current waveform is shown by the symbol ``■'' at point ``■'' in Figure 3.

This current causes the voltage of the distortion correction capacitor 15 to become zero. This is shown in Figure 3: Point voltage ■.

The resonance pulse generated during this resonance period is boosted on the secondary side of the flyback transformer 1o and charges the capacitor 13. It goes without saying that the heavier the secondary load 14 (the brighter the tab pattern), the greater the current that charges the capacitor 13 during this period. The primary inflow current of the flyback transformer 1o under heavy load is shown in FIG. 3 as a zero point current.

When the load is heavy, this primary inflow current injects a current into the flyback transformer 10 over almost the entire period of horizontal synchronization, which has a large DC component. After a resonance period between the resonant capacitor 7, the horizontal deflection coil 8, and the primary coil of the flyback transformer 100, the DC component flows through the turned-on damper diode 6 and the capacitor 15, and returns to the power source 11. This current generates a voltage in the capacitor 15, which serves as a distortion correction voltage.

After this, when the horizontal output transistor 5 is turned on, the charge in the capacitor 15 flows through the figure-8 correction capacitor 9, the horizontal deflection coil 8, the output transistor 5, and the ground, and the charge in the capacitor 15 is instantly discharged. Becomes zero. After this, diode 16 is turned on, and the current from deflection coil 8 returns to figure-8 correction capacitor 9 through transistor 5, ground, and diode 16.

As explained above, the horizontal deflection circuit operates.

Now, in case of heavy load, horizontal output transistor 5 is turned off.
During the period, the primary inflow current of the flyback transformer 10 flows into the distortion correction co-capacitor 15, causing the capacitor 15 to generate a voltage corresponding to the inflow current. Here, the current flowing into the capacitor 5 changes depending on the brightness of the screen (high voltage load), and the voltage across the capacitor 5 changes. When the screen is bright, the voltage across the capacitor 15 increases, and accordingly the voltage across the S-hand correction capacitor 90 decreases, reducing the sensitivity of the horizontal deflection circuit and reducing the horizontal picture size.

Distortion correction is performed through the operations described above.

However, the conventional circuit system described above requires two diodes with high withstand voltage and low current, such as 6 and 16, and recently developed horizontal output with a built-in damper diode that reduces cost. Conventional horizontal output circuits with distortion correction circuits had the disadvantage of not being able to use transistors, and were disadvantageous in terms of cost.

Furthermore, when using the conventional horizontal output circuit with a distortion correction circuit as described above, when a bright picture B is displayed in the center of the TV screen as shown in Fig. 4, the distortion correction There is a phenomenon in which a portion becomes an ineffective corner and distortion remains (see the raster position indicated by point b-b in Fig. 4).

This will be explained below with reference to FIG.

Furthermore, Fig. 5 shows the signal waveforms in each part of the circuit in Fig. 2 when the raster is in the dark part (a-a' in Fig. 4) and the bright part (b-b' in the same figure) of the picture. It is a waveform diagram shown for comparison.

Figure 5 (a-a') shows the distortion correction operation waveforms of each part of the circuit in Figure 2 at points a-a' on the screen in Figure 4;
The distortion correction operation waveform at point -b' is shown in (bb').

Now, at point a-a in Figure 4, the screen is dark, so the high voltage load is light. Therefore, the direct current component to the flyback transformer 10 is small. For this reason, there is a return current to the power supply 11 as shown by the 0 point (■) in FIG. 5 (a-a'). When the return current begins to flow during the ON period of the tamper diode 6, the voltage across the capacitor 15 becomes almost zero V as described in the operation description above.
Most of the return current flows through diode 16.

This is shown by the 0 point ■ in FIG. 5 (a-a').

Due to this, the stain current is diode 16, diode 6,
Power supply 1 passes through the primary coil of flyback transformer 10
Return to 1. That is, when the load is light, the diode 16 is ONI, and during this period the voltage across the capacitor 15 is approximately zero.

This condition continues during load conditions where there is current flowing back from the flyback transformer 10 to the power supply 11. That is,
After the diode 16 is in the ONL no load condition,
Distortion correction is performed by storing a voltage proportional to the load state in the capacitor 15.

At point b-vi in Figure 4, there is no sudden increase in load;
This shows a state in which the diode 16 is turned on. For this reason, distortion correction cannot be applied.

As described above, the conventional circuit system has the drawback that distortion correction cannot be effected when the load increases slightly, and distortion remains in the upper part of bright patterns.

[゛Object of the invention]

The present invention has been made to overcome the drawbacks of the prior art as described above, and therefore, an object of the present invention is to enable the use of an economical horizontal output transistor with a built-in damper diode, and to It is an object of the present invention to provide a horizontal output circuit with a distortion correction circuit capable of making the distortion correction radius effective even when the load increases slightly.

[Summary of the invention]

In order to achieve the above object, the present invention provides three parallel connections: a horizontal output transistor connected in parallel with a Dan <- diode, a series circuit of a horizontal deflection yoke and a figure-eight correction capacitor, and a resonant capacitor. In a horizontal output circuit for a television receiver including a circuit, a power supply is connected on the positive side to the high voltage side of the parallel connection circuit via a flywheel transformer primary coil, and the negative side of this power supply is connected to the high voltage side of the parallel connection circuit. A third capacitor and a switching element are connected in parallel between the low voltage side of the circuit, and the switching element and the horizontal output transistor are driven with voltages of the same polarity. The element is turned off before the horizontal output transistor, so that the feedback current from the primary coil of the blueback transformer to the power source does not flow through the switching element, but flows through the third capacitor. It is characterized by the fact that

[Embodiments of the invention]

The present invention will now be described in detail with reference to the drawings.

FIG. 6 is a circuit diagram showing one embodiment of the present invention.

In the same figure, components given the same reference numerals as in FIG. 2 have the same functions. In addition, 17 is a horizontal output transistor with a damper diode, 18 is a transistor as a switching element, 19 is a horizontal drive transformer, and Y' is a distortion correction circuit added according to the present invention.

FIG. 7 is an operational waveform diagram of each part in the circuit of FIG. 6 when the picture is bright.

The circuit operation will be explained with reference to FIGS. 6 and 7.

Reference numeral 19 is a horizontal drive transformer for driving the circuit according to the present invention. There are two secondary windings; one drives the horizontal output transistor 17 and the other drives the distortion correction control transistor 18. The polarity of both secondary windings shall be the same. Figure 8 ■ shows the voltage and current waveforms at each point of the drive transformer.

(2) and cl are shown, while (2) and [F] are shown to flow currents of the same polarity.

In the above circuit configuration, horizontal output transistor 1
7 is ON, the horizontal deflection current from the figure-8 correction capacitor 9 passes through the horizontal deflection coil 8, passes through the transistor side of the horizontal output transistor 17 with a built-in damper diode, and returns to the figure-8 correction capacitor 9. The signal from the power supply 11 returns to the power supply 11 through the primary side of the flyback transformer 10, through the transistor side of the horizontal output transistor 17, through the distortion correction control transistor 18, and through the ground. During the first period when the transistor 18 is ON, the charge stored in the distortion correction capacitor 15 is also discharged through the transistor 18. This is shown in Figure 8 as ``■'' in the point ``waveform'' and ``■'' in the point ``waveform''.

Next, apply the same polarity OFF to the second winding on the secondary side of the horizontal drive winding.
When a signal is output, horizontal output transistor 17 and transistor 18 are turned off, but if T8 (register storage time) of transistor 18 is shorter than that of horizontal output transistor 17, transistor 18 will be turned off first. Therefore, at this time, the primary current of the flyback transformer 100 flows while charging the capacitor 15. This is shown in the point waveform (■) in Figure 7. This current generates a voltage in the capacitor 15, and this voltage acts as a reverse bias voltage for the distortion correction transistor 18.

Both transistors are then turned off. The continuous current in the horizontal deflection coil 8 then charges the resonant capacitor 7.

Further, the continuous current of the primary coil of the flyback transformer 10 flows through the resonance capacitor 7 and the distortion correction capacitor 15. This is shown in the 0-point waveform (■) in FIG.

After this, the discharge current of the capacitor 7 is transferred to the horizontal deflection coil 8.
It will flow through the figure 8 correction capacitor 9. Part of it is of course the primary side of the flyback transformer 10, the power supply 1
1, ground, flowing through capacitor 15. This current is shown by ■ in the zero point current waveform in FIG.

The resonance pulse generated during this resonance period is boosted on the secondary side of the fly current transformer 10 and charges the capacitor 13. It goes without saying that the heavier the secondary load 14, the greater the current that charges the capacitor 13 during this period.

Naturally, during the OFF period of the horizontal output transistor 17, the distortion correction control transistor 18 is also OFF, and during this period, all the primary current of the flyback transformer 100 flows through the distortion correction capacitor 15.

In this way, distortion can be corrected by generating a voltage in the capacitor 15 in accordance with the load, similar to the conventional circuit system.

Next, when the horizontal output transistor 17 is on, the distortion correction control transistor 18 also discharges the charge of the ONL capacitor 15 and resets it. In this way, the horizontal deflection operation in the television receiver continues.

With the above configuration, the voltage across the capacitor 15 changes as the high voltage load increases, and the voltage of the figure-8 correction capacitor 9 can be modulated accordingly, allowing distortion correction to take effect, just as in the conventional circuit system. I can do and.

In the case of light load (when the DC component to the flyback transformer 10 is small), the primary current of the flyback transformer 100 is fed back to the power supply 11 during the damper period, as in the conventional case, but at this time, the capacitor 15 has a , the horizontal output transistor 17 is turned on.

When the distortion correction control transistor 18 is OFF, almost the voltage charged by the power supply 11 remains, and this is shown in FIG. 7 [F].
The point waveform is shown in ■. That is, the distortion correction control transistor 1
8 is applied with a reverse bias.

In other words, the voltage between the collector and base of the transistor 18 is high (71), so that all the feedback current to the power supply 11 is passed through the capacitor 15, and the charge previously stored in the capacitor 15 is discharged. Flows while discharging.

At medium load, the feedback current from the flyback transformer 10 to the power supply 11 decreases (because the DC component to the flyback transformer increases), but even at this time, all the current flows through the capacitor 5, reducing the capacitor charge. .

However, when the load is medium, the feedback current to the power source 11 is smaller than when the load is light, and the amount of discharge from the capacitor 5 is also small. This corresponds to an increase in the voltage of the capacitor 5 when the load becomes a medium load.

When the load is heavy, there is no return M current to the power source 11, and current flows from the power source 11 into the flyback transformer 10 over the horizontal circumference. At this time, the control transistor 8 is naturally OFF and the capacitor 5 is charged.

In the circuit configuration as shown above, from light load to heavy load, all the primary current of the flyback transformer flowing when the horizontally suspended quadrant sister 7 is OFF is passed to the distortion correction capacitor 5. It is possible to faithfully correct distortion by changing the capacitor voltage according to the load.

FIG. 8 is a circuit diagram showing a modified embodiment of the present invention. In the circuit shown in the figure, the horizontal excitation transformer 30 secondary coil is
However, the point that voltages of the same polarity are applied to the bases of the transistors 17 and 18 is the same as in the embodiment shown in FIG. 6, and the point that the transistor 18 is turned off before the transistor 17 is also different. It's the same. The operation of the pick-up circuit is the same as that shown in FIG.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to use a transistor with a built-in damper diode adjacent to it, and only the primary inflow current of the flyback transformer and the discharge current of the distortion correction capacitor are passed through the distortion correction control transistor. Therefore, the entire circuit can be constructed at low cost. Also, the horizontal output transistor pTs is used as the distortion correction control transistor.
By using a transistor with a short storage time and turning it off first, it is possible to faithfully correct screen distortion from light loads to heavy loads without configuring a complicated circuit.

Furthermore, by connecting a current limiting resistor in series with the distortion correction capacitor, the capacity of the distortion correction control transistor can be further reduced, and costs can be reduced accordingly.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of a TV screen when distortion correction is not performed, Figure 2 is a circuit diagram showing a conventional horizontal output circuit equipped with a distortion correction circuit, and Figure 3 is a signal waveform at each part of the circuit in Figure 2. Figure 4 is an explanatory diagram of a TV screen when using a conventional horizontal output circuit with distortion correction circuit, and Figure 5 shows when the raster is in the dark part of the picture and in the bright part. A waveform diagram showing a comparison of signal waveforms in each part of the circuit shown in the figure,
FIG. 6 is a circuit diagram showing one embodiment of the present invention, FIG. 7 is a waveform diagram of each part of the circuit in FIG. 6 when the pattern is bright, and FIG. 8 is a circuit diagram showing a modified embodiment of the present invention. be. Description of symbols 15... Distortion correction capacitor, 18... Distortion correction control transistor Agent Patent attorney Akio Namiki Figure 1 Figure 2 Figure 4 Figure 5 Figure 6 Figure 8 = □□□ □□□−]n; p: ,,,l υゝ■ ト/ =OA −〇V

Claims (1)

[Claims] 1) In a horizontal output circuit for a television receiver that includes a horizontal output transistor with a damper diode connected in parallel, a series circuit of a horizontal deflection yoke and a figure-8 correction capacitor, and a resonant capacitor. , a power source is connected on the positive side to the high voltage side of the parallel connection circuit via a flyback transformer primary coil, and a third capacitor is connected between the negative electrode side of the power source and the low voltage side of the parallel connection circuit. A switching element is connected in parallel, and the switching element and the horizontal output transistor are driven with voltages of the same polarity, and when driving,
The switching element is turned off before the horizontal output transistor, so that the feedback current from the primary coil of the flyback transformer to the power source does not flow through the switching element but through the third capacitor. A horizontal output circuit characterized by a flowing flow.