MXPA97007682A - Automatic paragnetic disassembly circuit to co - Google Patents

Abstract

The present invention relates to a computer monitor or similar device, wherein the monitor includes: a color kinescope (CPT), a demagnetizing coil to demagnetize the monitor, a circuit of energy conservation mode to locate the monitor in a Low power consumption mode at the time when the primary power of the monitor is still in the on position and a demagnetizing circuit to detect a release of said energy conservation mode and to provide a demagnetization control signal which causes said coil demagnetizing machine develops a demagnetization operation in response to the release of the energy conservation mode, regardless of whether or not said primary energy has been transferred by cyclone

Description

AUTOMATIC DEFAULT CIRCUIT FOR COLOR CINESCOPE BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to a color kinescope of a monitor.

In particular, the present invention relates to a degaussing circuit for a color kinescope (CPT) which can automatically demagnetize the CPT when a power conservation mode of the monitor is released. 2. Description of the Prior Art Generally, in a CPT, the electron beams that have been emitted from a heated sample by a heater are controlled, accelerated, focused and then hit phosphor points on a fluorescent screen of the CPT to display a video signal . During these procedures, electromagnetic waves are produced from the CPT, and exert harmful influence on the peripheral circuits of the CPT and the human body. According to the above, to eliminate said electromagnetic waves, the CPT is provided with a degaussing apparatus to demagnetize the electromagnetic field that occurs instantaneously especially when the energy is initially provided.

According to the conventional degaussing apparatus, if an energy switch is turned on and an initial energy is supplied to the CPT, the degaussing apparatus operates for a predetermined time to demagnetize the electromagnetic waves produced by the CPT. As a result, the degaussing apparatus carries out the demagnetizing operation only when the energy is initially supplied, > the demagnetizing operation will not take place until the initial energy is supplied again after the power is turned off.

Recently, most video display devices such as monitors employ an energy conservation function to prevent unnecessary consumption of power from the device. Thus, during a normal operation of the apparatus where a mode of energy conservation is released, the demagnetizing operation is not carried out without operating a separate degaussing switch. If said choke switch is not provided in the apparatus, the electromagnetic waves produced by the CPT can not be eliminated at all during the normal operation of the CPT.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the problems involved in the prior art and to provide a degaussing circuit that can automatically perform the de-aggregating operation of the CPT when the energy conservation mode is released regardless of the ignition status / switch off the degausser switch.

To achieve the above objective, a degaussing circuit is provided for a CPT having a demagnetizing coil for eliminating the electromagnetic waves, the degaussing circuit comprises a detecting section of the energy conservation mode for detecting a release of a conforming energy conservation mode. to the energy conservation signal of the CPT entered therein and providing a demagnetizing control signal to control an operation of the degaussing coil if the release of the energy conservation mode is detected, and a driving section of the degaussing coil for driving the demagnetizing coil for a predetermined time according to the demagnetization control signal input from the energy conservation mode detecting section when the energy conservation mode is released.

BRIEF DESCRIPTION OF THE DRAWINGS The above objective, other characteristics and advantages of the present invention will be more apparent when describing the preferred example thereof with reference to the attached drawings, in which: Figure 1 is a schematic circuit diagram of the circuit automatic degausser for a CPT according to the present invention.

Figures 2A to 2F are waveform diagrams illustrating the waveforms at various points in Figure 1.

DETAILED DESCRIPTION OF THE PREDILECT EXAMPLE Figure 1 shows the construction of the automatic degaussing circuit for a CPT according to the present invention.

With reference to Figure 1, the automatic degaussing circuit for CPT according to the present invention includes a degaussing coil Ll, installed in an appropriate portion of the CPT, for demagnetizing electromagnetic waves produced by the CPT, a thermistor THl, a terminal of which is connected to a terminal of the degaussing coil Ll, a bridge rectification section BDl, coupled between the other terminal of the degaussing coil Ll and a terminal of a power switch SW1, to rectify a supply of energized AC power, a detector section of the energy conservation mode 10 for detecting a release of an energy conservation mode in accordance with a energy conservation mode signal supplied to it from an energy conservation circuit (not illustrated) of the CPT, and which emits a demagnetization control signal to control the operation of the degauss coil Ll if the release of The energy conservation mode is detected, and a driving section of the degaussing coil for driving the degaussing coil Ll for a predetermined time in accordance with the demagnetizing control signal fed from the detecting section of the energy conservation mode 10 when the mode Energy conservation is released.

The detector section of the energy conservation mode 10 includes a transistor Ql to carry out a switch operation according to the energy conservation mode signal, a Zener diode ZDl to pass through itself a voltage provided by the operation of transistor switch Ql only when the voltage is greater than the Zener voltage itself to prevent the erroneous operation of the energy conservation mode detecting section 10, a transistor Q2 to carry out a switch operation in accordance with the voltage provided through the Zener diode ZDl, a resistor R8 and a capacitor C3, connected between the anode of the Zener diode ZDl and the base of the transistor Q2, to determine an interruption time of the transistor Q2. A polarization voltage of 12V is supplied to the collector of the transistor Ql and the sampling of the Zener diode ZDl through the resistor R6.

Meanwhile, the driving section of the degaussing coil 20 includes a relay RL1, whose mobile contacts are connected to a thermistor terminal TH1 and a terminal of the power switch SW1, respectively, to control the voltage supplied to the degaussing coil Ll through the thermistor TH1, a Zener diode ZD2, coupled to the terminal of output of the detector section of the energy conservation mode , to pass through there a voltage supplied by the output of the sensing section of the energy conservation mode 10 only when the voltage is greater than the voltage Zener thereof, and a transistor Q3, connected to a pulse coil of the relay RL1, to control the operation of the relay RL1 in accordance with the voltage supplied through the Zener diode ZD2. The polarization voltage of 12V is supplied to the other terminal of the driving coil of the relay RL1 and the sampling of the Zener diode ZD2.

In Figure 1, the reference numeral Rl denotes a resistance for the prevention of overvoltage, Rl to R7 denote resistances, and Cl, C2 and C4 denote capacitors.

The operation of the CPT degaussing circuit according to the present invention as the above-constructed one will now be explained in detail with reference to Figures 1, 2 A to 2F.

With reference to Figure 1, if the power switch SW1 is on, the common contact c of the relay RL1 is in contact with the moving contact a in an initial state, and thus, as illustrated in Figure 2A, a driving voltage of the degaussing coil is supplied to the degaussing coil Ll through the thermistor THl. According to the above, the degaussing coil Ll is driven to carry out the demagnetizing operation.

Specifically, in the initial state of the CPT, the transistor Q2 in the detecting section of the energy conservation mode 10 is turned off, while the transistor Q3 is the driving section of the degaussing coil 20 is turned on. In accordance with the above, a driving voltage is supplied to the driving coil of the relay RL1, which causes the common contact c of the relay RL1 to come into contact with the moving contact a. Thus, the driving voltage of the degaussing coil is supplied to the degaussing coil Ll through the contacts of the relay RL1 and the thermistor TH1, so that the degaussing coil Ll carries out the demagnetizing operation.

In this state, if the resistance value of the thermistor TH1 increases as a predetermined time passes, no further operational current flows to the degaussing coil Ll through the thermistor TH, which causes the operation of the demagnetizing coil Ll to be stop On the other hand, if the power conservation mode of the CPT is on, a "high" energy conservation mode signal is fed from the power conservation circuit of the CPT to the base of the Ql transistor in the sensing section of the energy conservation mode 10 through the divider resistors R4 and R5. Thus, the transistor Ql is turned on, and the voltage of 12 V passes through the resistor R6 and the collector / emitter path of the transistor Q1. According to the above, no voltage is applied to the Zener diode ZDl and a "low" level signal is applied to the base of the transistor Q2, which causes the transistor Q2 to turn off.

As the transistor Q2 in the detecting section of the energy conservation mode 10 is turned off, the driving voltage is supplied to the base of the transistor Q3 through the Zener diode ZD2 in the driving section of the degaussing coil, which causes the transistor Q3 is turned on, and thus the driving voltage flows to ground through the driving coil of the relay RL1 and the transistor Q3. In accordance with the foregoing, the common contact c of the relay RL1 is brought into contact with the mobile contact b, so that the supply of energy to the degaussing coil Ll through the thermistor TH1 is intercepted. As a result, during the energy conservation mode of the CPT, the degaussing coil is not driven.

In this state, if the energy conservation mode is released or switched off, a "low" energy conservation mode signal as shown in Figure 2 is applied to the base of the transistor Ql in the detector section of the energy conservation mode 10, which causes transistor Ql to turn off. Thus, the collector voltage of transistor Ql is increased as illustrated in Figure 2C according to the time constant of resistor R6 and capacitor C2.

Specifically, if the collector voltage of the transistor Ql is increased more than the Zener voltage of the Zener diode ZDl, the Zener diode ZDl is turned on, and the voltage that has passed through the Zener diode ZDl is applied to the base of the transistor Q2 as shown in FIG. illustrated in Figure 2D. Accordingly, the transistor Q2 is turned on, and thus the driving voltage supplied to the Zener diode ZD2 in the driving section of the degaussing coil 20 flows through the transistor Q2 in the detecting section of the energy conservation mode 10.

At this time, if the voltage charged to the capacitor Cl has been substantially discharged, the Zener diode ZD2 and the transistor Q3 are turned off sequentially as illustrated in Figure 2E, so that no impulse current flows to the relay driving coil. RLl, which causes the common contact c to come into contact with the mobile contact a. In accordance with the foregoing, the driving voltage of the degaussing coil is supplied to the degaussing coil Li through the contacts of the relay RL1 and the thermistor TH1, and thus the degaussing coil Ll is driven to perform the demagnetizing operation.

Here, the time period ti as shown in Figure 2C is determined by the resistance R6 and the capacitor C2, and the time period t2 as illustrated in Figure 2D is determined by the resistance R8 and the capacitor C3.

Thereafter, if the period of time t2 has passed since the release of the energy conservation mode, the transistor Q2 in the detector section of the energy conservation mode 10 is turned off since the capacitor C3 is fully charged by the current flowing to the capacitor C3 in the detecting section of the energy conservation mode 10. As the transistor Q3 is turned off, the capacitor Cl in the driving section of the degaussing coil 20 is gradually loaded in accordance with the time constant of the resistor R3 and the capacitor Cl as illustrated in Figure 2E.

At this time, if the charged voltage of the capacitor becomes higher than the Zener voltage of the Zener diode ZD2, this Zener diode ZD2 is turned on, and the voltage across the Zener diode ZD2 is applied to the base of the Q3 transistor, so that the transistor Q3 is turned on and the common contact c of the relay RL1 comes into contact with the moving contact b. Accordingly, the 1-shunt coil drive voltage which is supplied to the choke coil 11 through the thermistor THl is intercepted to stop the demagnetizing operation of the choke coil Ll. As a result, when the predetermined time is exhausted after the release of the energy conservation mode, the operation of the degauss coil Ll is automatically stopped.

Here, the Zener diode ZDl in the sensing section of the energy conservation mode 10 prevents the driving section of the degaussing coil 20 from operating erroneously due to instantaneous feeding of an abnormal pulse.

As described above, according to the present invention, the CPT is automatically demagnetized for a predetermined time when the energy conservation mode is released on a monitor having energy conservation function, thereby improving the capacity and reliability of the monitor .

• While the present invention has been described and illustrated herein with reference to the preferred exemplary thereof, it will be understood by those skilled in the art that various changes in form and detail can be made to the present without departing from the spirit and scope of the invention.

Claims (5)

1. CLAIMS: 1. A degaussing circuit for a color kinescope (CPT) having a degaussing coil to eliminate electromagnetic waves, the degaussing circuit comprises: a detecting section of the energy conservation mode for detecting a release of the energy conservation mode of conformance to a power conservation mode signal of said CPT fed thereto and providing a demagnetization control signal to control an operation of said degaussing coil if said release of said energy conservation mode is detected; and a driving section of the degaussing coil for driving said degaussing coil for a predetermined time in accordance with said demagnetization control signal fed from said detecting section of the energy conservation mode when said energy conservation mode is released.
2. 2. A degaussing circuit as claimed in claim 1, further comprising a thermistor, connected in series to said degaussing coil, to control the flow current to said degaussing coil.
3. 3. A degaussing circuit as claimed in Claim 1, wherein said energy conservation mode detecting section comprises: a first transistor for performing a switch operation in accordance with said energy conservation mode signal; a Zener diode to pass through itself a voltage supplied in accordance with said switch operation of said first transistor only when said voltage is greater than a Zener voltage of said Zener diode to prevent an erroneous operation of said detector section of the mode of conservation of Energy; and a second transistor for carrying out a switch operation in accordance with said voltage supplied through said Zener diode.
4. 4. A degaussing circuit as claimed in claim 1, wherein said driving section of the degaussing coil comprises: a relay for controlling said voltage supplied to said degaussing coil; a Zener diode coupled to said detector section of the energy conservation mode, to pass through itself a voltage supplied in accordance with an output of said detector mode of energy conservation mode only when said voltage is greater than a Zener voltage of said Zener diode; and a transistor, connected to said relay, for controlling an operation of said relay in accordance with said voltage supplied through said Zener diode.
5. 5. A degaussing circuit for a color kinescope (CPT) having a degaussing coil for eliminating electromagnetic waves, the degaussing circuit comprises: a thermistor, connected to said degaussing coil, to control an amount of current flowing to said degaussing coil; a bridge rectifier section, coupled to said degaussing coil and an energy switch, for rectifying an input AC power; a relay, coupled to said thermistor and said power switch, for controlling a driving voltage supplied to said degaussing coil through said thermistor- a detecting section of the energy conservation mode for detecting a release of an energy conservation mode of conformance to a power conservation mode signal of said CPT fed thereto and providing a demagnetizing control signal to control an operation of said degaussing coil if said release of said energy conservation mode is detected; and a driving section of the degaussing coil for driving said degaussing coil upon driving said relay for a predetermined time in accordance with said demagnetizing control signal fed from said detecting section of the energy conservation mode when said energy conservation mode is released. EXTRACT E THE INVENTION An automatic degaussing circuit for a color kinescope (CPT) capable of automatically degaussing the CPT when an energy conservation mode is released on a monitor having an energy conservation function. The degaussing circuit includes a degaussing coil to eliminate electromagnetic waves produced from the CPT, a detector section of the energy conservation mode for detecting the release of the energy conservation mode in accordance with a signal from the energy conservation mode of the CPT fed to it and providing a demagnetization control signal to control the operation of the degaussing coil if the release of the energy conservation mode is detected, and a driving section of the degaussing coil to drive the degaussing coil for a predetermined time in accordance with the demagnetizing control signal when the energy conservation mode is released .