JPH01261082A - Horizontal deflection circuit - Google Patents

Abstract

PURPOSE:To prevent distortion or reduction of a screen attended with such a cause as over adjustment of brightness by operating a saturable transformer and increasing a deflection current in response to the propagation of deflection energy based on the result of detection of a circuit current corresponding to the propagation of the deflection energy from a primary side to a secondary side. CONSTITUTION:When the brightness of a cathode ray tube 15 is increased, an output is extracted from the secondary side of a flyback transformer 8 and a deflection energy of the primary side is propagated to the secondary side, a high voltage output current IH is increased and it is detected by a current detection section 17. A DC amplifier 20 converts a detected DC current into a voltage and then amplifies it and gives its amplified output to a control coil 23 of a saturable transformer 18. Thus, the inductance of a coil 22 to be controlled of the saturable transformer 18 is decreased, a current flowing to the deflection coil 6 is increased, the deflection energy is propagated from the primary side to the secondary side and even if the current flowing to the horizontal deflection coil 6 is decreased, the reduction is immediately compensated. Thus, reduction and distortion caused on the screen is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a horizontal deflection circuit equipped with means for controlling deflection current.

[Conventional technology]

FIG. 6 shows a general horizontal deflection circuit used in television receivers and general CRT display devices.

This general circuit consists of horizontal deflection output circuit 1 and high voltage circuit 2.
and a high-voltage stabilizing circuit 11 with a high-voltage output voltage E□. The horizontal deflection output circuit 1 includes a horizontal output transistor 3, a damper diode 4, a resonant capacitor 5,
It consists of a horizontal deflection coil 6 and a three-figure correction capacitor 7. The horizontal output transistor 3 performs a switching action in response to voltage pulses sent from a horizontal drive circuit (not shown), and in cooperation with the damper diode 4 causes the horizontal deflection coil 6 to have a sawtooth shape as shown in FIG. 7(b). A wave current 17 is applied. On the other hand, the resonant capacitor 5 and the horizontal deflection coil 6 generate a flyback pulse (collector pulse e) as shown in FIG. 7(a) due to their resonance action.
c is generated and applied to the high voltage circuit 2.

The high voltage circuit 2 includes a flyback transformer 8 and a high voltage rectifier diode 10. One side terminal of the low voltage coil (minus coil) 12 of the flyback transformer 8 is connected to the collector side of the horizontal output transistor 3 and the damper diode 4.
and a common terminal of the horizontal deflection coil 6 and the resonant capacitor 5 , and the other end terminal of the low voltage coil 12 is connected to the input power source 13 .

On the other hand, a high voltage side terminal of a high voltage coil (secondary coil) 14 of the flyback transformer 8 is connected to an anode 16 of a cathode ray tube 15 via the high voltage rectifier diode 10.

In addition, the high voltage stabilizing circuit 11 suppresses fluctuations in the high voltage specific voltage E which changes due to brightness adjustment of the cathode ray tube 15, etc.
This stabilizes Ell to a constant level.

In this circuit configuration, the high voltage circuit 2 boosts the flyback pulse applied from the horizontal deflection output circuit 1 using the flyback transformer 8, further rectifies the signal using the high voltage rectifier diode IO, and outputs the rectified output (high voltage output voltage) Eo. is added to the anode 16.

(Problems to be Solved by the Invention) Generally, in this type of horizontal deflection circuit, deflection energy is held on the negative side. This deflection energy is 'A
It is expressed as L v ·I''.

However, LV: Inductance of the horizontal deflection coil 6 IY: Value from O to the peak value of the waveform of the horizontal deflection current iY (7th
Figure (b)).

Assuming that L v << L + (L r is the inductance of the low voltage coil 12), the deflection energy can be expressed as y2Lyl"yζ'AC,E"ゎ.

However, C8: Capacitance of the resonant capacitor 5 Ec: Voltage of the positive component of the flyback pulse (FIG. 7(b)).

This y2C+E''c means the energy on the primary side during the retrace period.

In this way, when the output is taken from the secondary side of the flyback transformer 8 by brightness increase adjustment etc. while the deflection energy is held on the -next side, the deflection energy is transmitted from the -next side to the secondary side. , EC decreases.

If this decrease in EC is ΔEc, then y2LY(IY-ΔIy)" = y2C, (Ec-ΔEc)z, and I7 also decreases by Δ17. This decreasing state is represented by the dotted line waveform in FIG. 7(b). This decrease in deflection energy causes the amplitude of the screen to decrease under a constant Ell condition, and for example, as shown in FIG. If the image is made brighter, the amplitude becomes smaller in that area, which has the disadvantage of causing screen reduction distortion.

The present invention has been made to solve the above-mentioned conventional problems, and its purpose is to provide a horizontal display that does not cause screen distortion even if the deflection energy moves from the primary side to the secondary side due to brightness increase adjustment, etc. The object of the present invention is to provide a deflection circuit.

[Means to solve the problem]

In order to achieve the above object, the present invention is configured as follows. That is, the present invention has a horizontal output transistor that performs a switching action in response to a voltage pulse sent from a horizontal drive circuit; a horizontal deflection coil that horizontally deflects the electron beam of a cathode ray tube; a damper diode that applies a sawtooth wave to the deflection coil; a resonant capacitor that generates a flyback pulse by resonance with the horizontal deflection coil; a flyback transformer that boosts the flyback pulse and applies a high output voltage to the anode of the cathode ray tube. and: a high-voltage output voltage stabilizing circuit; and a current detection section for detecting a high-voltage output current in a horizontal deflection circuit having;
A control coil and a controlled coil are wound around the core in such a manner that they are not magnetically coupled, and the controlled coil has a saturable transformer connected in series to the deflection coil side; A DC amplifier for amplifying and applying the amplified current to the control coil of the saturable transformer is provided.

[Effect]

In the present invention configured as described above, when the brightness of the cathode ray tube increases, the output is taken from the secondary side of the flyback transformer, and the deflection energy on the negative side moves to the secondary side, the high voltage output current 111 increases. To increase. And for example,
This increase in the DC component of I□ is detected directly or indirectly by the current detection section. The DC amplifier converts the DC current detected by the current detection section into a voltage, amplifies it, and applies the amplified output to the control coil of the saturable transformer.

That is, when IH increases, the current applied to the control coil also increases in accordance with the increase. Thus, when the current flowing through the control coil increases, the magnetic flux passing through the core of the saturable transformer increases, and the inductance of the controlled coil of the saturable transformer decreases accordingly.

When the inductance of the controlled coil decreases, the inductance of the series connection body of the controlled coil and the deflection coil decreases, so that the current flowing through the deflection coil (deflection current) is increased. Therefore, even if the deflection energy moves from the primary side to the secondary side and the current flowing through the horizontal deflection coil decreases, this decreased amount of current is immediately replenished, and this effectively reduces the reduction distortion that occurs on the screen. This will be prevented.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings. In the description of this embodiment, the same reference numerals are given to circuit parts that are the same as those of the conventional example, and redundant explanation thereof will be omitted.

FIG. 1 shows a circuit diagram of a horizontal deflection circuit showing one embodiment of the present invention. The circuit of this embodiment includes a saturable transformer 18 and a current detection section 1 in addition to the conventional circuit shown in FIG.
7 and a DC amplifier 20.

The saturable transformer 18, as shown in FIG.
, 210, the controlled coil 22 is divided into parts, with a first divided winding part 22a and a second divided winding part 22b between them, and a first divided winding part 23 outside the controlled coil 22.
a and a control coil 23 which is divided into parts and has a second divisional winding part 23b.

The number of turns nz+ of the first divided winding portion 22a of the controlled coil 22 and the number of turns n of the second divided winding portion 22b are the same number of turns (n21=flZ□) and are wound in opposite directions,
The magnetic flux φ21 generated in the core 21 by the first divided winding portion 22a and the magnetic flux φ generated in the core 21 by the second divided winding portion 22b are equal in opposite directions (φ2
1=φ2□). As shown in FIG. 1, the winding end side of the first divided winding portion 22a
is connected to a common connection between the emitter of the damper diode 4, the anode of the damper diode 4, and one end of the resonant capacitor 5. It is connected in series with the coil 6. On the other hand, the control coil 23 is connected to the first divided winding section 2.
3a and the second divided winding portion 23b are wound in the same direction.
and the number of turns n11 of this first divided winding portion 23a,
The number of turns n and □ of the second divided winding portion 23b are equal (n II"' n 1 *In addition, the core 21
Magnets 24a and 24b are fixed using an adhesive or the like to both ends of the magnets 24a and 24b so as to apply a bias magnetic field in the same direction.

The current detection section 17 is constituted by a detection resistor 25. One end of the detection resistor 25 is connected to the low voltage side (winding start side) of the high voltage coil 14, and the other end is connected to a reference potential (earth side in the figure). The detection resistor 25 converts the high voltage current I11 into voltage and detects it.If the resistance value of the resistor 25 is R, then ■□X
A voltage at RH is developed across resistor 250.

The DC amplifier 20 has a first input terminal 20a, a second input terminal 20b, a first output terminal 20c, and a second output terminal 20d, and the first input terminal 20a has a detection resistor 25. The second input terminal 20b is connected to one end of the resistor 2.
5, the first output terminal 20c is connected to the control coil 23.
The second output terminal 20d is connected to the winding start side of the coil 23.
are connected to the end of each winding. The DC amplifier 20 amplifies the high-voltage output current that is converted into a voltage value and detected by the current detection section 17, and applies the amplified output to the control coil 23.

In this embodiment configured as described above, the brightness of the cathode ray tube 15 is adjusted, and when the brightness increases, the deflection energy on the primary side moves to the secondary side as described above, and the screen is likely to cause reduction distortion. shall be. The circuit of this embodiment prevents this screen distortion as follows.

First, when the brightness is adjusted in the direction of increasing, the high voltage output current ■□ increases. This high-voltage output current ■A is detected by the detection resistor 25 as a voltage of ■□×R)I, and this detection voltage is amplified by the DC amplifier 20 as a ripple-free DC component voltage, and the amplified output is sent to the control coil 23. added to. In this case, if the amplified output is large, the control current l flowing through the control coil 23 becomes correspondingly large.

By the way, for example, at a certain point in the retrace period, as shown in FIG. A magnetic flux φ2□ due to the second divided winding portion 22b of 22, a magnetic flux φ, r due to the magnets 24a and 24b, and a magnetic flux φ1 due to the number of turns n, , +n12 of the control coil 23 are generated, respectively.

In this case, φ2. Since and φ are equal in size and opposite in direction, φ, l and φ2□ cancel each other out. In this example, φ,〉φz+ (φz+=φ2□)
The number of turns of each coil is set so that the following relationship holds true, and the magnetic coupling between the control coil 23 and the controlled coil 22 is completely cut off. Therefore, both coils 22.2
3 is prevented, and the voltage of the horizontal deflection component occurring between the controlled coils 22 is not converted and appears on the control coil 23 side.

FIG. 3 shows the operating characteristics of a saturable transformer.

In the figure, the horizontal axis shows the magnetic flux φ passing through the core 21, and the vertical axis shows the inductance L of the controlled coil 22 with respect to this magnetic flux φ. In this characteristic diagram, when the horizontal deflection circuit is operating normally, that is, when I++=0, φ=0, so the magnetic flux φ passing through the core 21 is φ
=φHG, the saturable transformer 18 operates with φ=φMG, and the inductance L of the controlled coil 22 at that time is
, l=LxM. At this time, the deflection current iv flowing through the horizontal deflection coil 6 is iv #E,, X t/(
Lv +LXM). However, E is the input power supply 13
voltage, Lv is the inductance of the horizontal deflection coil 6, t
is time.

On the other hand, when a high-voltage output current 1 flows through the anode 16 of the cathode ray tube 15 due to brightness increase adjustment or the like, the current 1. flows, the magnetic flux passing through the core 21 is φ=φMG
+φ, the operating point of the saturable transformer 18 shifts from φNG to φMG+φ, and as a result, the controlled coil 22
The inductance of I changes from LXM to L□.

In this way, when the inductance L of the controlled coil 22 becomes smaller, the inductance of the series connection of the controlled coil 22 and the horizontal deflection coil 6 becomes smaller, so the deflection current iV flowing through the horizontal deflection coil 6 increases. The deflection current 17 at this time is iy "iEm X t/(Lv +
LXM). This increase in deflection current iv means that the high-voltage output current I11 becomes thicker (if it becomes thicker, it becomes larger correspondingly).
This compensates for the decrease in the current flowing through the horizontal deflection coil 6 due to the movement of deflection energy from the negative side to the secondary side, and effectively prevents screen reduction distortion that occurs when adjusting brightness, etc. It turns out.

Note that the present invention is not limited to the above-mentioned embodiments (and may take various embodiments).

For example, in the above embodiment, the detection resistor 25 constituting the current detection section 17 is connected to the high voltage coil 14, and the high voltage output voltage is
However, unlike this, as shown in FIG. 4, a detection resistor 25 is connected between the emitter of horizontal output transistor 3 and the reference potential (ground in the figure), and Alternatively, as shown in FIG. 5, a detection resistor 25 may be connected to the low-voltage coil 12 side, and the current l flowing through the coil 12 may be detected. In either case, correction control of the deflection current iv will be performed based on the detected current.

Further, in the above embodiment, the first divided winding part 23a and the second divided winding part 23b of the control coil 23 are wound in the same direction, and the first divided winding part 22a and the second divided winding part 22a of the controlled coil 22 are wound in the same direction. The portion 22b is wound in the opposite direction, but this is reversed and each divided winding portion 23a, 23 of the control coil 23 is wound in the opposite direction.
b may be wound in opposite directions, and the divided winding portions 22a and 22b of the controlled coil 22 may be wound in the same direction. However, in this case, the magnets 24a and 24b are provided with opposite polarities so that magnetic fields in opposite directions are applied.

Further, in this embodiment, the magnets 24a and 24b are provided at both ends of the core 21, but they may be provided only at one end of the core 21, and in some cases, these magnets 24a and 24b may be provided at both ends of the core 21. May be omitted. However, if the magnets 24a and 24b are omitted, the control current flowing through the control coil 23 must be increased.
For this purpose, it is necessary to increase the capacity of the DC amplifier 20.

Furthermore, in this embodiment, the core 23 is formed into a regular character shape, but the shape of the core 21 is not necessarily limited to this, and cores with other shapes such as an El-shaped core may be used. I can fully accomplish my purpose.

〔Effect of the invention〕

Since the present invention is configured as explained above,
When the deflection energy on the primary side moves to the secondary side due to brightness adjustment, etc., and the deflection current decreases, and the screen is about to cause shrinkage distortion, the deflection energy moves from the primary side to the secondary side. Based on the detection results of the corresponding circuit current,
A saturable transformer operates. By the operation of this saturable transformer, the inductance of the controlled coil on the secondary side of the saturable transformer connected in series with the horizontal deflection coil is controlled to be small. The deflection current increases. This increase in deflection current immediately compensates for the decrease in deflection current caused by the movement of the deflection energy from the primary side to the secondary side, and the reduction distortion of the screen caused by adjusting the brightness increase etc. is effectively prevented. That will happen.

In addition, since the circuit of the present invention is constructed using a flyback transformer and a saturable transformer, there is an advantage that the entire circuit can be AC isolated into so-called hot side and cold side using these cores as a boundary. .

Further, since the present invention uses a saturable transformer and controls the deflection current by a magnetic circuit, there is an advantage that the temperature drift of the circuit can be reduced.

Further, according to the present invention, it is possible to control the deflection current without causing any trouble to the ABL signal.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of an embodiment of the present invention, FIG. 2 is a cross-sectional configuration diagram of a saturable transformer, FIG. 3 is an operating characteristic diagram of the saturable transformer, and FIGS. 4 and 5 are diagrams of other embodiments of the present invention. Figure 6 is a circuit diagram of a conventional general horizontal deflection circuit, Figure 7 is an operational waveform diagram of flyback pulses and deflection current, and Figure 8 shows the occurrence of screen distortion. It is an explanatory diagram showing a state. 1...Horizontal deflection output circuit, 2...High voltage circuit, 3...
・Horizontal output transistor, 4... Damper diode, 5... Resonant capacitor, 6... Horizontal deflection coil,
7... Three-character correction capacitor, 8... Flyback transformer, lO... High voltage rectifier diode, 11... High voltage stabilization circuit, 12... Low voltage coil, 13... Input power supply, 14... ...High voltage coil, 15...Cathode ray tube,
16... Anode, 17... Current detection section, 18...
・Saturable transformer, 20... DC amplifier, 21...
Core, 21 a + 21 b + 21 c...Brim, 22... Controlled coil, 22a... First divided winding section, 22b... Second divided winding section, 23... Control Coil, 23a...first divided winding section, 23b...
Second divided winding portion, 24a, 24b... magnet,
25...Detection resistor.

Claims (1)

[Claims] a horizontal output transistor that performs a switching action in response to voltage pulses sent from a horizontal drive circuit; a horizontal deflection coil that horizontally deflects the electron beam of the cathode ray tube; and a sawtooth-shaped horizontal deflection coil that cooperates with the horizontal output transistor; a damper diode that applies a wave; a resonant capacitor that generates a flyback pulse by resonance with the horizontal deflection coil; a flyback transformer that boosts the flyback pulse and applies a high output voltage to the anode of the cathode ray tube; a high output voltage. A current detection section for detecting a high-voltage output current; A control coil and a controlled coil are wound around the core in such a manner that they are not magnetically coupled, and the controlled coil is connected to the deflection coil. a saturable transformer connected in series on the side; and a DC amplifier that amplifies the circuit current detected by the current detection section and applies it to the control coil of the saturable transformer. Deflection circuit.