Lamp control system

A lamp control system driving at least two discharge lamps according to at least two control instructions includes a control circuit, a switch circuit, a transformer resonance circuit, and a source transformer circuit. The control circuit generates a control signal to which the source transformer circuit is electrically connected, transforming the control signal to at least one alternating current (AC) signal, and the transformer resonance circuit is electrically connected to the source transformer circuit and the discharge lamps, transforming the at least one AC signal to one or more electrical signals to respectively drive one or more discharge lamps, the switch circuit, electrically connected to the source transformer circuit and the transformer resonance circuit, drives source transformer circuit output of the at least one AC signals to the transformer resonance circuit.

BACKGROUND

1. Field of the Invention

The disclosure relates to lamp control, and more particularly, to a lamp control system of a liquid crystal display (LCD) system.

2. Description of related art

Discharge lamps, such as cold cathode fluorescent lamps (CCFLs), are often used as light sources in LCD panels. Generally, the CCFL is driven by an alternating current (AC) signal generated by an inverter circuit.

Two or more pairs of CCFLs are employed to illuminate a large LCD panel for providing sufficient brightness. Thus, the inverter circuit normally has many groups of outputs to generate sufficient AC signals to drive the CCFLs. However, the inverter circuit is usually controlled by one group of input control signals for generating many groups of synchronous and the same output signals.

Referring toFIG. 1, a lamp control system10receives a switch signal, and transforms the switch signal to two groups of uniform electrical signals to drive the first lamp10A and the second lamp10B simultaneously. The first lamp10A and the second lamp10B are controlled by the electrical signals, and are lit or extinguished simultaneously. If there is a requirement to lower brightness of the LCD panel (not shown) employing the lamp control system10, only one lamp needs to be lit at a time. The lamp control system10cannot fully illuminate the LCD panel while lowering its brightness level to conserve power consumption.

SUMMARY

According to the requirements related to the foregoing descriptions, it is necessary to provide a lamp control system which can meet the requirements of brightness and conservation of energy consumption simultaneously when the LCD panel is required to lower its brightness level.

According to an exemplary embodiment of the disclosure, a lamp control system controlling a plurality of lamps includes a control circuit, a source transformer circuit, a transformer resonance circuit, and a switch circuit. The control circuit receives a group of switch signals and transforms the switch signals to a control signal. The source transformer circuit is electrically connected to the control circuit and transforms the control signal to at least one AC signal. The transformer resonance circuit is electrically connected between the source transformer circuit and the lamps, and transforms the at least one AC signal to one or more electrical signals to drive the lamps. The switch circuit is electrically connected to the source transformer circuit and controls the source transformer circuit to output the at least one AC signal to the transformer resonance circuit. Accordingly, the transformer resonance circuit is directed to output the one or more electrical signals to drive the one or more lamps.

Other advantages and novel features of the disclosure will be apparent from the following detailed description of preferred embodiments thereof with references to the attached drawings, in which:

DETAILED DESCRIPTION OF THE EMBODIMENTS

FIG. 2is a schematic diagram of an application infrastructure of a lamp control system20of the disclosure. A first discharge lamp10A and a second discharge lamp10B are electrically connected to the lamp control system20. The lamp control system20receives a first switch signal and a second switch signal, and outputs a first electrical signal and a second electrical signal accordingly to drive the first lamps10A and the second lamp10B, respectively.

FIG. 3shows function modules of an exemplary embodiment of a lamp control system20A. In the exemplary embodiment, a first lamp10A and a second lamp10B are electrically connected to the lamp control system20A. The lamps10A,10B may be CCFLs.

The lamp control system20A includes a control circuit201A, a switch circuit202A, a source transformer circuit203A and a transformer resonance circuit204A. In the exemplary embodiment, the control circuit201A receives a first switch signal, subsequently transforming the first switch signal to a control signal. The first switch signal can be a digital square wave signal or a power source signal, such as a direct current (DC) signal. The switch circuit202A is electrically connected to the control circuit201A to control output of the control signal to the transformer circuit203A according to a second switch signal.

The source transformer circuit203A is electrically connected to the control circuit201A and the switch circuit202A, and comprises a first source transformer203A1and a second source transformer203A2. The first source transformer203A1is electrically connected to the control circuit201A, and transforms the control signal to a first AC signal. The second source transformer203A2is electrically connected to the control circuit201A through the switch circuit202A, and transforms the control signal transmitted by the switch circuit202A to a second AC signal.

The transformer resonance circuit204A includes a first transformer204A1and a second transformer204A2. A primary winding of the first transformer204A1is electrically connected to the first source transformer203A1, while a secondary winding of the first transformer204A1is electrically connected the first lamp10A. Therefore, the first AC signal is transformed to a first electrical signal to drive the first lamp10A. A primary winding of the second transformer204A2is electrically connected to the second source transformer203A2, while a secondary winding of the second transformer204A2is electrically connected to the second lamp10B. Therefore, the second AC signal is transformed to a second electrical signal to drive the second lamp10B.

Referring toFIG. 4, a schematic diagram of application of an embodiment of the disclosure is shown. For instance, the highest level of brightness of each lamp is assumed as 200 Nits. At time t1, the first switch signal is valid and the second switch signal is invalid, the switch circuit202A disconnects the electrical connection between the second source transformer203A2and the control circuit201A, and the control signal is not transmitted to the second source transformer203A2. As a result, only the first lamp10A is lit.

At time t2, both the first and second switch signals are valid, the electrical connection between the second source transformer203A2and the control circuit201A is enabled and the control signal is also transmitted to the second source transformer203A2through the switch circuit202A. Accordingly, the first transformer204A1and the second transformer204A2transform the AC signals output from the source transformer circuit203A1and the second source transformer203A2to the electrical signals to drive the lamps, respectively. Consequently, the first lamp10A and the second lamp10B are both lit.

At time t3, the first switch signal is invalid and the second switch signal is valid. In this state, there are no control signals transmitted to the first source transformer203A1and the second source transformer203A2. Accordingly, there are no signals transmitted to the first transformer204A1and the second transformer204A2. Consequently, neither the first lamp10A nor the second lamp10B is lit.

At time t4, the first switch signal and the second switch signal are both invalid. In this state, there are also no control signals transmitted to the source transformer203A1and the second source transformer203A2. Accordingly, there are no signals transmitted to the first transformer204A1and the second transformer204A2. Consequently, neither the first lamp10A nor the second lamp10B is further lit.

From the foregoing descriptions, it is concluded that the first switch signal controls whether all lamps are lit or not, and the second switch signal controls only the second lamp. That is, if the first switch signal is valid, the first lamp10A is lit, and lighting of the second lamp10B is dependent on the second switch signal. If the first signal is valid, the second lamp10B is not lit unless the second switch signal is valid. Thus, outputting a different second switch signal meets the practical requirements of lowered brightness and energy conservation. For example, if the two lamps are lit simultaneously, maximum brightness of the lamps is 400 Nits; and if only one lamp is lit, maximum brightness of the lamps is 200 Nits.

In the exemplary embodiment, the first switch signal and the second switch signal can be set according to practical requirements. For example, at the time t (t is a dynamic real number), the amplitudes and the phases of the first switch signal and the second switch signal can be synchronous or asynchronous, and the polarities of the first switch signal and the second switch signal can be the same or opposite. Correspondingly, the amplitudes and the phases of the electrical signals output from the lamp control system20A can be synchronous or asynchronous, and the polarities of the electrical signals can be the same or opposite. Accordingly, the electrical signals output from the lamp control system20A can selectively light one or more of the lamps to achieve various brightness.

FIG. 5is another exemplary embodiment showing a schematic diagram of function modules of another lamp control system20B. In this embodiment, the LCD includes two discharge lamps, labeled as a first lamp10A and a second lamp10B, both electrically connected to the lamp control system20B. The lamps may be CCFLs.

The lamp control system20B includes a control circuit201B, a switch circuit202B, a source transformer circuit203B and a transformer resonance circuit204B. In the exemplary embodiment, the control circuit201B receives a first switch signal and transforms it to a control signal. The first switch signal can be a digital square-wave signal or a power source signal, such as a DC signal. The source transformer circuit203B is electrically connected to the control circuit201B and transforms the control signal to an AC signal. The switch circuit202B is electrically connected to the source transformer circuit203B and impels the source transformer circuit203B to transform a second switch signal to an AC signal and output the AC signal to the transformer resonance circuit204B, consequently controlling the transformer resonance circuit204B to generate electrical signals to drive the first lamp10A and the second lamp10B.

The transformer resonance circuit204B comprises a first transformer204B1and a second transformer204B2. Primary windings of the first transformer204B1and the second transformer204B2are electrically connected to the source transformer circuit203B and the switch circuit202B, respectively, while secondary windings thereof are electrically connected to the first lamp10A and second lamp10B, respectively. Therefore, the transformer resonance circuit204B generates a first electrical signal and a second electrical signal to drive the first lamp10A and the second lamp10B. The electrical signals are transformed respectively by the AC signals output from the source transformer circuit203B and the switch circuit202B.FIG. 4references the effect of the exemplary embodiment, while omitting the descriptions.

Similarly, in the exemplary embodiment, the first switch signal and the second switch signal can be set according to practical requirements. For example, at time t (t is a dynamic real number), the amplitudes and the phases of the first switch signal and the second switch signal can be synchronous or asynchronous, and the polarities of first switch signal and the second switch signal can be the same or opposite. Correspondingly, the amplitudes and the phases of the electrical signals output from the lamp control system20B can be synchronous or asynchronous, and the polarities of the electrical signals can be the same or opposite. Therefore, the electrical signals output from the lamp control system20B can selectively light one or more lamps to achieve various levels of brightness.

In the disclosure, the lamp control system can respectively control a plurality of pairs of CCFLs to be extinguished or lit by two groups of external switch signals. Particularly, when there is a requirement to light only one lamp, it is not necessary to light all lamps in the LCD panel, thereby achieving the goals of lighting and conservation of power.

In summary, the disclosure satisfies the requirements of a utility patent. However, the foregoing descriptions is only the exemplary embodiment of the disclosure, any equal modifications or ornaments made by any people who are familiar with the feature of disclosure are involved in the scope of the present patent application.