KR20010011889A - convergence driving circuit of projection television apparatus - Google Patents

Abstract

PURPOSE: A circuit for driving a convergence of a projection television device is provided to compensate a convergence temperature drift after an aging process of the projection television device, so as to prevent a screen deterioration caused by the convergence temperature drift after the aging process. CONSTITUTION: A convergence amplifier(U1) inputs a convergence driving signal to a non-inverted terminal, and compares the inputted convergence signal with a feedback signal inputted to an inverted terminal, then performs a differential amplifying process. A convergence coil(VCL1) is connected between an output terminal of the convergence amplifier(U1) and a feedback node, which is connected to the inverted terminal of the convergence amplifier(U1). A damping resistor(R3) is connected to both ends of the convergence coil(VCL1). A compensating circuit is connected to the both ends of the convergence coil(VCL1), and responds to a change of a peripheral temperature to compensate a convergence temperature drift.

Description

Convergence driving circuit of projection television apparatus

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a convergence driving circuit of a projection television apparatus, and more particularly, to a convergence driving circuit of a projection television apparatus capable of minimizing temperature drift by varying a damping resistance in response to an ambient temperature.

CRT projection televisions install RGB monochromatic CRTs side by side on the same line, and display RGB screens respectively output from these three CRTs through a lens system on the screen.

Therefore, the exact convergence of each RGB picture on the screen acts as a very important factor in determining the picture quality.

Fig. 1 shows the configuration of a convergence driving circuit of a conventional CRT projection television. In FIG. 1, in the CRT projection television, each RGB picture signal emitted from three CRTs is enlarged through the lens system 30 and displayed on the screen 40. In addition, the convergence module 10 drives the three CRT vertical and horizontal convergence coils, respectively. The convergence driving circuit 20 inputs a driving signal provided from the convergence module through the coil L1 and the resistor R1 to the non-inverting terminal of the differential amplifier U1, and applies a feedback signal to the inverting terminal. do. The output terminal of the differential amplifier U1 is connected to one end of the convergence coil VCL1, and the other end of the convergence coil VCL1 is connected to the inverting terminal through parallel connection of the resistor R2 and the capacitor C2. . A damping resistor R3 is connected to both ends of the convergence coil VCL1, and a resistor R4 is connected between the other end of the convergence coil VCL1 and the ground.

In such a conventional convergence driving circuit, the internal temperature of the set rises after a certain time after aging compared to the initial driving, and thus, in response to the temperature characteristic drift of the internal circuits, unlike the initial convergence current, The characteristics of the convergence current will be different. In other words, there is a problem that the image quality is degraded due to the left and right convergence shift compared to the center of the screen.

SUMMARY OF THE INVENTION An object of the present invention is to provide a convergence driving circuit of a projection television that can compensate for convergence distortion caused by temperature drift by providing a temperature compensating circuit in a convergence driving unit in order to solve the problems of the prior art. There is.

1 shows a convergence driving circuit of a conventional projection television apparatus.

Fig. 2 shows a convergence driving circuit of the projection television apparatus according to the present invention.

<Explanation of symbols for main parts of drawing>

10: convergence module 20, 50: convergence driving unit

30 lens system 40 screen

52: correction circuit R3: damping resistance

U1: Differential amplifier NTC: Thermistor

In order to achieve the above object of the present invention, the apparatus of the present invention, in the convergence drive unit for driving the convergence coil of the television device, the convergence drive signal is input to the non-inverting terminal, A convergence amplifier for comparing and amplifying a feedback signal and the input convergence signal, a convergence coil connected between a feedback node connected to an output terminal of the convergence amplifier and an inverting terminal of the convergence amplifier, And a damping resistor connected to both ends of the convergence coil, and connected to both ends of the convergence coil, and having compensation means for compensating for the convergence temperature drift in response to a change in the ambient temperature inside the apparatus.

Hereinafter, with reference to the accompanying drawings, it will be described in detail the present invention through an embodiment of the present invention.

2 shows a convergence driving circuit of a projection television apparatus according to the present invention. In FIG. 2, the projection television includes three R cathode ray tubes CRT1, a G cathode ray tube CRT2, a B cathode ray tubes CRT3, a lens system 30 including a lens LR, LG, and LB, and a screen 40. It includes. It also includes a convergence module 10 and six convergence driving circuits 50.

The convergence module 10 outputs the vertical and horizontal convergence driving signals RV, high, GV, arc, BV, and BH of three CRTs. The six convergence driving circuits 50 respectively input a corresponding convergence driving signal to drive the convergence coil.

The convergence driving circuit 50 includes resistors R1 to R6, diodes D1 to D4, capacitors C1 and C2, differential amplifiers U1, and thermistors NTC. The convergence signal provided from the convergence module 10 is input to the non-inverting terminal of the differential amplifier U1 through the resistor R1 and the coil L1. The feedback signal fed back from the convergence coil VCL1 through the parallel connection of the capacitor C2 and the resistor R2 is input to the inverting terminal of the differential amplifier U1.

One end of the convergence coil VCL1 is connected to the output terminal of the differential amplifier U1, the other end is grounded through the detection resistor R4, and the differential amplifier is connected through the parallel connection of the capacitor C2 and the resistor R2. It is connected to the inverting terminal of (U1).

Damping resistors R3 are connected to both ends of the convergence coil VCL1, and a compensation circuit 52 is connected. The compensation circuit 52 is connected between one end of the convergence coil VCL1 and the intermediate node N1, such as a thermistor NTC, and an intermediate node N1 and the feedback node N2. And the first correction amount setting means composed of the diode D3 and the resistor R5 to correct the first side and right distortion of the convergence, and is connected between the intermediate node N1 and the feedback node N2 to convert And second correction amount setting means composed of a diode D40 and a resistor R6 to correct the left side distortion of the second switch.

That is, since the output impedance of the compensation circuit 52 is connected to the damping resistor R3 in parallel, the total damping resistance value is determined by the sum of the parallel resistances.

--------(One)

------ (if intermediate node voltage is negative)

------ (if intermediate node voltage is negative)

Therefore, as the temperature of the set rises, the resistance value of NTC decreases, so the value of Z decreases, and thus the denominator value of Equation (1) increases, so that the total damping resistance value decreases and the current flowing to the damper increases. . Therefore, the current flowing through the convergence coil VCL1 is reduced, and thus offsets the incremental value of the convergence current due to the temperature rise, thereby maintaining the originally set convergence current.

On the contrary, when the temperature decreases, the resistance value of NTC increases, so the value of Z increases, and thus the denominator value of Equation (1) decreases, so that the total damping resistance value increases, and the current flowing to the damper decreases. Therefore, the current flowing through the convergence coil VCL1 is increased to offset the decrement of the convergence current due to the temperature drop, thereby maintaining the originally set convergence current.

Therefore, even in the initial state of the set and the state after aging, the convergence current is kept in the same state as the initial convergence current.

In the present invention, when the drift occurs at the set level, the base amount to be corrected by the damping resistance is set, and the base amount is set to follow the drift by NTC by calculating the drift amount according to time. Subsequently, after setting the overall drift amount, the left correction amount is determined as R5, and the right correction amount is determined as R6 in consideration of the degree of distortion on the left and right sides.

Therefore, it is possible to dynamically control the amount of drift at the set level by adjusting the time constant of the damping circuit.

As described above, in the present invention, the resistance value of the damping resistor connected in parallel to the convergence coil is automatically changed according to the temperature in order to compensate for the variation of the convergence current in response to the change in the internal temperature of the projection television set. By varying and compensating in the direction of suppressing temperature drift, the convergence current can be stabilized and thus the image quality can be improved.

Although the above has been described with reference to a preferred embodiment of the present invention, those skilled in the art will be variously modified and changed within the scope of the present invention without departing from the spirit and scope of the invention described in the claims below. I can understand that you can.

Claims (4)

In the convergence drive unit which drives the convergence coil of the television device, A convergence amplifier for inputting a convergence driving signal to the non-inverting terminal and differentially amplifying the feedback signal inputted to the inverting terminal and the input convergence signal; A convergence coil connected between an output terminal of the convergence amplifier and a feedback node connected to an inverting terminal of the convergence amplifier; Damping resistors connected to both ends of the convergence coil; And And means for compensating for convergence temperature drift in response to a change in the ambient temperature inside the device, connected to both ends of said convergence coil. The method of claim 1, wherein the compensation means A temperature sensitive variable resistor connected between one end of the convergence coil and an intermediate node; First correction amount setting means connected between said intermediate node and said feedback node for correcting a first side skew of convergence; And And a second correction amount setting means connected between said intermediate node and said feedback node for correcting a second side skew of convergence. The method of claim 2, The first correction amount setting means includes: a first diode connected forward between the intermediate node and a feedback node to pass a negative component of the convergence driving signal; And a first correction resistor connected between the cathode of the first diode and the feedback node and set as a resistance value for correcting the first side distortion. The second correction amount setting means includes: a second diode connected in a reverse direction between the intermediate node and a feedback node to pass a positive component of the convergence driving signal; And a twenty-first correcting resistor connected between the anode of the second diode and the feedback node and set to a resistance value for correcting the second side distortion. In the convergence driving unit for driving the horizontal and vertical convergence coils of a projection television device including three monochromatic cathode ray tubes, each convergence driving circuit A convergence amplifier for inputting a convergence driving signal to the non-inverting terminal and differentially amplifying the feedback signal inputted to the inverting terminal and the input convergence signal; A convergence coil connected between an output terminal of the convergence amplifier and a feedback node connected to an inverting terminal of the convergence amplifier; Damping resistors connected to both ends of the convergence coil; And And means for compensating for convergence temperature drift in response to a change in the ambient temperature inside the apparatus, said convergence driving circuit being connected to said convergence coil.