JPH0210699Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field This invention relates to a horizontal deflection circuit for an image display device using a cathode ray tube.

BACKGROUND ART AND PROBLEMS Conventionally, a horizontal deflection circuit for an image display device using a cathode ray tube uses a power modulation method to correct left and right pincushion distortion. FIG. 1 shows an example of this type of horizontal deflection circuit.

In this circuit, the power supply voltage +B from the power supply terminal 2 applied to the horizontal output transformer 1 is modulated in the transistor 4 using a parabolic wave with a vertical period V from the terminal 3 (Fig. 2A). A horizontal deflection current with a horizontal period H flowing through the deflection coil 5 is modulated in a parabolic manner as shown in FIG. 2B, thereby correcting left and right pincushion distortion.

Note that 6 is a horizontal output transistor, 7 is a damper diode, 8 is a resonance capacitor, and 9 is an S-shaped correction capacitor.

In the operation of this circuit, the modulation parabola voltage changes rapidly during the vertical retrace period (see the part marked with ○ in Figure 2A), and the inductance of the horizontal output transformer 1, horizontal deflection coil 5, and S-shaped correction capacitor 9 changes rapidly. Because of L _HT , L _DY and capacitance Cs, at the beginning of the vertical period, Ringing occurs at frequency ₁ determined by . If this ringing does not attenuate within the vertical retrace period, it will appear as a wavy raster 10 at the top of the screen, as shown in FIG. This is a particularly noticeable drawback in cases where the vertical and horizontal frequencies are high and the vertical retrace period is short, such as in recent high-resolution displays.

Therefore, a method was devised to suppress the linking by adding a damping resistor to damp the inductance component as shown in FIG.

That is, a connection point between the horizontal output transformer 1 and the transistor 4 from which a modulated power supply voltage is obtained;
A damping resistor 11 is connected between the horizontal deflection coil 5 and the connection point of the S-shaped correction capacitor 9.
In the example shown, the damping resistor 11 is not directly connected to the modulated power supply voltage +B, but is connected via the horizontal centering circuit 12. 13
is the horizontal centering volume of this horizontal centering circuit 12, and 14 and 15 are horizontal centering voltage sources.

By the way, if the circuit of the horizontal output transformer 1, horizontal deflection coil 5, S-shaped correction capacitor 9, and damping resistor 11 is extracted from the circuit of FIG. 4, it becomes as shown in FIG. In the figure, R indicates the value of the resistor 11, L= _LHT + _LDY , and Cs indicates the capacitance of the S-shaped correction capacitor 9.

In the circuit of FIG. 5, if the charges moving through the resistor R and inductance L are q ₁ and q ₂ , respectively, the following equation holds true.

Ld ² q ₂ /dt ² +1/Cs (q ₁ +q ₂ )=E …(1) Rq ₁ =Ldq ₂ /dt …(2) From equations (1) and (2), Ld ² q ₂ /dt ² +L /CsR dq ₂ /dt+1/Csq ₂ =E...(3).

Now, assuming that q ₂ = Aε ^pt , and E = 0 in equation (3), (LP ² +L/CsRP+1/Cs)q ₂ = 0...(4), and P that satisfies equation (4) is P =-1/2CsR± [(1/2CsR) ² -1/LCs] ^1/2 …(
5) becomes.

In this equation (5), when (1/2CsR) ² -1/LCs≧0 (6), q ₂ becomes non-oscillatory, and therefore the charge q = q ₁ + q ₂ moving through capacitance Cs is also non-oscillatory. become a target.

In particular, when (1/2CsR) ² -1/LCs=0 (7), this circuit becomes critical damping, and the movement of charges can reach a steady state as quickly as possible without oscillating.

From equation (7) above, is obtained.

In this way, by selecting the value R of the damping resistor as shown in equation (8), a horizontal deflection circuit that does not cause ringing can be realized.

However, in the case of the above method, the horizontally periodic parabola wave voltage generated across the S-shaped correction capacitor 9 is short-circuited by the resistor 11, resulting in a drawback that power consumption increases. In other words, on the actual circuit, when the value R of the resistor 11 is determined using equation (8),
For example, the parabolic voltage of 20 to 30V _PP generated across the capacitor 9 is connected to this resistor R.
The power consumption amounts to several watts. Further, horizontal linearity will also be adversely affected.

In addition, when a horizontal centering circuit is included as shown in Figure 4, if the horizontal centering correction amount in this horizontal deflection circuit is, for example, 15 mm on each side, the current Ic required for the correction is equal to the current required for horizontal deflection. When it is about 8A, Ic=0.33 [A].
In order to cause this current Ic to flow through the horizontal deflection coil 5, the horizontal centering voltage is required to be at least 33V using the R, L series damping circuit described above when R=100Ω, and in that case, the voltage consumed by the resistor 11 is It can reach up to 10W.

Purpose of the invention This invention attempts to propose a horizontal deflection circuit that can effectively damp ringing without causing the above-mentioned drawbacks.

Summary of the invention This invention uses one resistor as a damping circuit.
The above disadvantages can be avoided by using a combination of a transformer and a resistor, and by selecting the inductance, mutual induction coefficient, and resistance value (including 0) of the primary and secondary windings of the transformer. This makes it possible to effectively damp ringing without causing any damage.

Embodiment Hereinafter, an embodiment of this invention will be described with reference to FIG. 6 and subsequent figures.

In this invention, a transformer and necessary resistance are used instead of a damping resistor. In the example shown in FIG. A winding 16a is connected, and a resistor 17 (resistance value) is connected between one end and the other end of the secondary winding 16b.
R _D ) is connected.

By using the transformer and the necessary resistors in this way, it is possible to reduce wasteful power consumption and obtain a good damping effect, as will be explained below.

Generally, as shown in Figure 7A, the mutual induction coefficient M
The two coils L ₁ and L ₂ coupled together can be expressed by the equivalent circuit shown in FIG. A circuit in which a resistor R _D is connected to the secondary winding L ₂ of this transformer can be expressed as shown in FIG. 8, which is almost equivalent to the circuit shown in FIG. 9.

Now, the values of each element in Figure 9 are as shown in the figure.
When L ₁ ′, L ₂ ′, R′, the ringing frequency is
₁ , for the horizontal deflection frequency ₂ , if L ₁ ′ and L ₂ ′ are selected so that 2π ₁ L ₂ ′≪R′≪2π ₁ L ₁ ′ …(9), then for the ringing frequency ₁ , In this case, the damping resistance R' becomes more dominant than the inductance component as the impedance at both ends, and the damping effect is effectively exerted. Also, at horizontal frequency ₂ , which is sufficiently higher than ringing frequency ₁ , since L ₁ ′≫L ₂ ′, the impedance due to L ₁ ′ is sufficiently large, and ignoring this, R′≪2π ₂ L ₂ ′ …(9 ′) If L ₂ ′ is selected, the impedance between both ends will be dominated by L ₂ ′ and will be sufficiently large, thereby achieving the intended purpose of reducing power consumption by the resistor R′. It should be noted that the horizontal centering current is approximately direct current, and it passes through L ₁ ' with almost zero impedance.

Now, if we calculate the impedance between the two terminals in Figures 9 and 8, we will obtain the following equations (10) and (11).

Impedance Z′ Z′=ω ² L ₁ ′ ² R′+Jω [L ₁ ′R′ ² +ω ² L ₁ ′L ₂ ′(L ₁
′+L ₂ ′)]/R′ ² +[ω(L ₁ ′+L ₂ ′)] ² …(10) Impedance Z in Figure 8 Z=ω ² R _D M ² +Jω[L ₁ R _D ² +ω ² (L ₁ L ₂ −M ² )L ₂ ]/R _D
² + (ωL ₂ ) ² ...(11) In order to satisfy Z=Z', the real and imaginary parts of each impedance must be equal.

R _D M ² /R _D ² +(ωL ₂ ) ² =L ₁ ′ ² R′/R′ ² + [ω(L ₁ ′
+L ₂ ′)] ² …(12) L ₁ R _D ² +ω ² L ₂ (L ₁ L ₂ −M ² )/R _D ² + (ωL ₂ ) ² = L ₁ ′R
′ ² +ω ² L ₁ ′L ₂ ′(L ₁ ′+L ₂ ′)／R′ ² +[ω(L ₁ ′+
L ₂ ′)] ² …(13) In order for these equations (12) and (13) to always hold regardless of ω, equations (12) and (13) must be identities regarding ω. If we set L ₂ ′=aL ₁ ′ here, we get the following relationship.

[L ₁ = L ₁ ′ ... (14) R _D = 1/1 + a・L ₂ /L ₁ R' ... (15) L ₁ L ₂ = (1 + a) M ² ... (16)] In other words, from equation (12) R _D ² R′L ₁ ′ ² +ω ² R′L ₁ ′ ² L ₂ ² =R _D M ² R′ ² +ω ² (L ₁ ′
+
L ₂ ′) ² R _D M ² …(12)−a From equation (13), R _D ² L ₁ ′R′ ² +ω ² [R _D ² L ₁ ′L ₂ ′(L ₁ ′+L ₂ ′)+
L ₂ ² L ₁ ′R′ ² ]+ω ⁴ L ₂ ² L ₁ ′L ₂ ′ (L ₁ ′+L ₂ ′)=R′ ² L
₁ R _D ² +
ω ² [R′ ² L ₂ (L ₁ L ₂ −M ² )+L ₁ R _D ² (L ₁ ′+L ₂ ′) ² ]+
ω ⁴ L ₂
(L ₁ L ₂ −M ² ) (L ₁ ′+L ₂ ′) ² …(13) −a In order for these to hold regardless of ω, it is necessary that they are identities with respect to ω, and (12 )−a, the term of ω ⁰ R _D ² R′L ₁ ′ ² = R _D M ² R′ ² …R _D L ₁ ′ ² = R′M ²
…(12)−b ω ² term R′L ₁ ′ ² L ₂ ² = (L ₁ ′+L ₂ ′) ² R _D M ² …(12)−
c From (13)-a, the term ω ⁰ R _D ² L ₁ ′R′ ² =R′ ² L ₁ R _D ² …L ₁ ′=L ₁
…(13)−b→(14) Equation ω ² term R _D ² L ₁ ′L ₂ ′ (L ₁ ′+L ₂ ′) + L ₂ ² L ₁ ′R′ ² = R
′ ² L ₂
(L ₁ L ₂ −M ² )+L ₁ R _D ² (L ₁ ′+L ₂ ′) ² …(13)−c ω ⁴ term L ₂ ² L ₁ ′L ₂ ′(L ₁ ′+L ₂ ′) = L ₂ (L ₁ L ₂ −M ² )
(L ₁ ′+L ₂ ′) ² …L ₂ L ₁ ′L ₂ ′=(L ₁ L ₂ −M ² )(L ₁ ′+L
₂ ′)
…(13)-d where (13)-b→(14) Equation L ₁ = L ₁ ′ and L ₂ ′=
Substituting aL ₁ ′ into (12)-c, (13)-c, and (13)-d, R′L ₁ ² L ₂ ² =L ₁ ² (1+a) ² R _D M ² …R′L ₂ ² = (1+
a) ² R _D M ² …(12)−d R _D ² L ₁ ³ a(1+a)+L ₁ L ₂ ² R′ ² =R′ ² L ₂ (L ₁ L ₂ −
M ² )+L ₁ ³ (1+a) ² R _D ² …R′ ² L ₂ M ² =L ₁ ³ R _D ² (1+
a)...(13)-e aL ₁ ² L ₂ = (L ₁ L ₂ -M ² )L ₁ (1+a)...(1+
a) M ² = L ₁ L ₂ ...(13)-→(16) Formula once again, put these formulas together (12)-b R _D L ₁ ′ ² = R′M ² (12)-d R′ L ₂ ² = (1+a) ² R _D M ² (13)-b (14) Equation L ₁ ′=L ₁ (13)-e R′ ² L ₂ M ² =L ₁ ³ R _D ² (1+a) ( 13)-(16) Equation (1+a) M ² = L ₁ L _{2Substituting} (13)-b...(14) of equation (12)-b, M ² = R _D /R'L ₁ ² ...(12 )−e Substitute (12)−e into (12)−d R′L ₂ ² = (1+a) ² R _D・R _D /R′L ₁ ² …R _D =1/1+
a L ₂ /L ₁ R'...(15) Substitute equation (12)-e into (13)-e R' ² L ₂ R _D /R'L ₁ ² = L ₁ ³ R _D ² (1+a)... R _D =1/1+
a L ₂ /L ₁ R'...Equation (15) Therefore, Equations (14) to (16) are obtained from these equations.

Furthermore, since L ₂ /L ₁ is equal to 1/n ² when the turns ratio of the transformer is n, (15), equation (16) can be rewritten as follows.

R _D =1/1+a・1/n ² R′ …(17) M ² =1/1+a・L ₁ ² /n ² …(18) L ₂ =1/n ² L ₁ …(19) From the above, When the values L ₁ ′, L ₂ ′, and R′ in Figure 9 are determined, if the turns ratio n of the transformer is arbitrarily selected, (14)
From equations (17), (18), and (19), L ₁ , L ₂ , M, and R _D are obtained. That is, L ₁ ′, L ₂ ′, and R′ in FIG. 9 can be realized by using transformers having the respective values determined by equations (14), (17), (18), and (19).

By the way, generally in a transformer, L ₁ , L ₂ ,
If k is the joining coefficient between M, then the following holds true: M=k√ _{1 2} (20). (16) From equations (20), k ² =1/1+a (21), and from the above conditions, L ₁ ′≫L ₂ ′ and L ₂ ′=aL ₁ ′, the value of k becomes close to 1. That is, the bonding state between L ₁ and L ₂ needs to be quite dense.

Also, since 1≫a, R _D ≒ 1/n ² R' (22) is obtained from equation (17), and even if the DC resistance of the secondary winding 16b is used as the resistance R _D , the number of turns is By appropriately selecting the ratio n, it is possible to obtain the desired R'. In this case, it is sufficient to connect both ends of the secondary winding 16b without further providing the secondary resistor 17.

Effects of the device As described above, in this device, 1.
Transformer and resistance (including 0) with appropriately selected inductance and mutual induction coefficient of the next and secondary windings
Since this combination is used as a ringing damping circuit, it is possible to realize a horizontal deflection circuit that is sufficiently effective against ringing and consumes less wasteful power.

In this case, instead of using a transformer and a resistor, two coils and one resistor are used as in the ideal circuit shown in Figure 9.
However, if a transformer is used as in this invention, the number of parts can be reduced. In particular, by selecting the turn ratio between the primary winding and the secondary winding of the transformer, it is possible to reduce the number of parts as described above. If you do not need an external resistor on the secondary winding side, use transformer 1.
It has the advantage that only one person is required.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram of an example of a conventional horizontal deflection circuit.
FIG. 2 is a waveform diagram for explaining the problem, FIG. 3 is a diagram for explaining the drawback, FIG. 4 is a diagram showing a conventional improvement example of the drawback, and FIG. 5 is for explaining the operation. , and FIG. 6 are circuit diagrams of an example of this invention, and FIGS. 7 to 9 are diagrams for explaining essential parts of this invention. 1 is a horizontal output circuit, 2 is a power supply terminal, 3 is an input terminal for vertically periodic parabolic wave voltage, 4 is a modulation transistor, 5 is a horizontal deflection coil, 9 is an S-shaped correction capacitor, 12 is a horizontal centering circuit, 16 is a A transformer and 17 are resistors.

Claims (1)

[Scope of utility model registration request] By modulating the power supply voltage applied to the horizontal output transformer using a parabolic wave with a vertical period,
In a horizontal deflection circuit of an image display device using a cathode ray tube, in which the horizontal deflection current flowing through the horizontal deflection coil is modulated in a parabolic manner to correct left and right pincushion distortion, the points at which the modulated power supply voltage is obtained and the above The primary winding of the transformer is connected between the horizontal deflection coil and the connection point with the S-shaped correction capacitor, and a resistor is connected between both ends of the secondary winding of this transformer. A horizontal deflection circuit in which the inductance and mutual induction coefficient of the next winding and the value (including zero) of the resistor are selected to damp ringing.