JP3344772B2 - Deflection yoke - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deflection yoke installed in a cathode ray tube of a television receiver or the like.

[0002]

2. Description of the Related Art At present, a deflection yoke used particularly for a display is mainly provided with a correction circuit for correcting misconvergence. The convergence of the correction by the correction circuit can be easily adjusted as compared with the correction by the ferrite sheet, and the appearance can be viewed because the ferrite sheet is not attached.

In this correction circuit, coils such as a coma coil, a two-pole coil, a four-pole coil, a six-pole coil, and an MCM are used to correct misconvergence.
The switching of the coil is performed using a diode, and the problem here is the temperature characteristic of the diode. Diode, as shown in FIG. 7, lower the forward voltage V _F with increasing temperature T, as shown in FIG. 8, the output current I _O with increasing temperature T increases.
On the screen, for example, on the top side, as shown in FIG. 10, the switching voltage of the diode decreases due to the temperature rise, the on-voltage decreases, and the output current increases, so that the current flowing through the correction coil increases. Therefore, P1,
Misconvergence occurs when the point P2 falls and becomes a barrel magnetic field.

[0004]

In such a conventional configuration, since a diode is used in the correction circuit of the deflection yoke, a current flowing through the diode changes due to a change in temperature due to a temperature characteristic of the diode. As a result, the current flowing through the correction coil also changes, causing a convergence temperature drift.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a deflection yoke in which the current flowing through the correction coil does not change even when the temperature changes and the current flowing through the diode changes, so that temperature drift of convergence does not occur. I do.

[0006]

Means for Solving the Problems To solve the above problems,
Deflection yoke of the present invention in order in the vertical circuit, comprising a plurality of correction coils for correcting the misconvergence complement
A correction coil group, and a die in series with the correction coil group.
Connect an ode to switch each correction coil, and
In the deflection yoke for correcting the misconvergence ,
Connect the thermistor in parallel against the said correction coils,
The thermistor, a current flowing through the correction coils, characterized by being configured to constant kept as temperature <br/> degree compensation regardless change of the ambient temperature.

[0007]

According to the structure of the present invention, a thermistor is connected in parallel to the correction coil to generate the temperature when the temperature changes.
A change in the current of the correction coil due to the temperature characteristic of the diode is compensated.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A deflection yoke according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of a vertical correction circuit 1 provided in a deflection yoke of the present embodiment. In FIG.
4-pole coils L1, L2, L3, L4, L for performing _YH correction
5, L6, L7, L8 switching diodes D1,
The bypass resistor R1 for D2, D3, and D4 has a thermistor Th1 and the bypass resistor R2 has a thermistor Th.
2 are connected in parallel.

The operation of improving convergence by the vertical correction circuit 1 in the above configuration will be described below. FIG. 2 is a diagram showing the positional relationship between the four-pole coils L1 to L8 and the electron guns B, G, R from the screen side. L1 and L2 are first-stage correction coils on the screen top side, and L3 and L4 are 2
This is a stage correction coil. L5 and L6 are 1 at the bottom of the screen
L7 and L8 are second-stage correction coils.

[0010] For example, where a vertical magnetic field of the deflection yoke are designed barrel tends magnetic fields in view of the landing, but red right misconvergence becomes pins trend in the Y _H section the barrel magnetic field is weak to generate . Therefore, in order to correct the misconvergence, the magnetic field b as shown in FIG.
1 and b2 are generated.

FIG. 5 is a diagram showing a convergence pattern on the screen at the time of the first-stage correction on the top side of the screen.
FIG. 8 is a diagram showing a convergence pattern at the time of second-stage correction on the bottom side of the screen.

The convergence pattern corrected as described above indicates that the diode D
Misconvergence occurs as shown in FIG. 10 due to the temperature characteristics 1 to D4. In this misconvergence, the convergence is shifted due to a rise in temperature from the state in which the convergence is matched in FIGS. 5 and 6. As the temperature rises, the ON voltages of the diodes D1, D2, D3, and D4 decrease, and the forward current I _O
Increase. As a result, the amount of current flowing into the correction coils L1 to L8 increases. The magnetic flux l shown in FIG.
The forces F1 and F2 received from 1,12 increase, and red is overcorrected to the right and blue is overcorrected to the left, and misconvergence occurs.

In order to eliminate the misconvergence shown in FIG. 10, the thermistors Th1 and Th1 as shown in the circuit diagram of FIG.
2 is connected in parallel to the bypass resistors R1 and R2. Bypass resistor R1, the bypass resistor R2 is a resistance for determining the amount of Y _H correction constants of the resistors R1, R2 diode D
1, diode D2, diode D3, diode D4
It changes depending on the temperature characteristic of. FIG. 7 shows diodes D1 to D
4 Temperature - forward voltage characteristics, FIG. 8 is a temperature - a graph showing the forward current characteristics, while FIG. 9 is a table showing similarly, the temperature characteristics of the diode D1~D4 the amount of Y _H correction to change, we determine the constant of the thermistor Th1, Th2 in the calculation the following method as Y _H correction amount is maintained constant by using a thermistor Th1, Th2.

[0014] bypass resistor R1 for determining the Y _H correction without connecting the thermistor Th1, Th2 in FIG 1, R2
Is measured as x when the temperature is low and Y when the temperature is high. The constants of the thermistors Th1 and Th2 are set as unknown numbers, and a is set at a low temperature and b is set at a high temperature.

A = t · b (where t is a resistance ratio) Expression 1 As shown in Expression 1, the resistance ratio t is calculated from the temperature characteristic graphs of the thermistors Th1 and Th2, The constants a and b are connected by an equation.

X = R · a / (R + a) Equation 2 As shown in Equation 2, the constant x of the bypass resistors R1 and R2 at low temperature and the thermistor Th are added to the bypass resistors R1 and R2.
1 and Th2 are connected in parallel by an equation.

Y = R · b / (R + b) Equation 3 As shown in Equation 3, the constant y of the bypass resistors R1 and R2 at high temperature and the thermistor Th in the bypass resistors R1 and R2 are used.
1 and Th2 are connected in parallel by an equation.

From the equations (1), (2) and (3), the thermistor Th1,
Th2 constants are determined, and the thermistor T of each constant is determined.
h1 and Th2 are connected to predetermined positions. With the above configuration, the currents I ₀ , I ₁ , I 3, I
No. 4 can be improved from the conventional characteristics shown in FIG. 4 to the characteristics shown in FIG. Therefore, even when the temperature changes and the current flowing through the diode changes, the current flowing through the correction coil does not change, and the occurrence of the convergence temperature drift can be prevented.

[0019]

As described above, according to the present invention, a thermistor is arranged in the vertical correction circuit of the deflection yoke, and the change in the current of the correction coil due to the temperature characteristic of the diode, which occurs when the temperature changes, is obtained. Therefore, even if the temperature changes and the current flowing through the diode changes, the current flowing through the correction coil does not change and the occurrence of temperature drift of convergence can be prevented.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a deflection yoke vertical correction circuit according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a four-pole coil of a deflection yoke used in the embodiment.

FIG. 3 is a diagram showing temperature characteristics of currents at various parts in the embodiment.

FIG. 4 is a diagram showing a temperature characteristic of a current of each part in the related art.

FIG. 5 is an explanatory diagram of a first-stage correction by a four-pole coil of a deflection yoke;

FIG. 6 shows the first stage and the second stage of the deflection yoke using the four-pole coil.
Explanatory drawing of stage correction

FIG. 7 is a temperature characteristic diagram of a forward voltage of a diode.

FIG. 8 is a temperature characteristic diagram of a forward current of a diode.

FIG. 9 is a comparison diagram of temperature characteristics of a forward voltage and a forward current of a diode.

FIG. 10 is an explanatory diagram of a temperature drift of convergence due to a conventional deflection yoke.

[Explanation of symbols]

 1 vertical correction circuit L1 to L8 correction coil Th1, Th2 thermistor

Claims (1)

(57) [Claims] A vertical circuit has a correction coil group including a plurality of correction coils for correcting misconvergence, and a diode is connected in series to the correction coil group.
To switch each correction coil,
In the deflection yoke to correct the Zensu, connect the thermistor in parallel against the said correction coils, the thermistor
The current flowing through the correction coil group to the ambient temperature.
To temperature compensation to keep constant irrespective of the change in time
A deflection yoke , wherein the deflection yoke is constituted .