Light module with control of luminance and method for managing the luminance

The invention is directed to a light module, which allows the individual lamp unit to be replaced with a new one and the luminance of the newly-replaced lamp unit can be automatically or manually adjusted to get a uniform luminance. Wherein, information of a first relation table of a lamp luminance versus a using time and a second relation table of the lamp luminance versus an operation current-power is used to determine the current power. In addition, a clocking unit is used to count a total using time for the light module. Then, a desired lamp luminance according to the first relation table can be determined, and then the current power is determined according to the second relation table.

BACKGROUND OF THE INVENTION

1. Field of Invention

The present invention relates to a light module. More particularly, the present invention relates to a light module with control of brightness. The light module can be used as a back light module in a panel display.

2. Description of Related Art

Display is the key tool to display communication information as an image manner for viewing by people. For example, computer system or TV system need a display for displaying the image. Recently, the display technology has been greatly developed. The display mechanism for panel display, such as the liquid crystal display (LCD), is quite different from the rather conventional cathode-ray-tube (CRT) display, and has been successfully developed. The LCD device usually needs a light module, such as a backlight module, to serve as the light source, so that each image pixel can produce the desired color light, and then a full image is formed.

A conventional LCD is, for example, shown inFIG. 1. InFIG. 1, the LCD100includes a bezel frame102. A displaying cell assembly104for displaying the image is held by the frame102. Then, several device elements, such as a plastic frame106, an optical film & diffuser plate108, lamp holders110a,110b, a light module112, a reflection sheet114, and a back cover116are sequentially stacked behind the displaying cell assembly104, so as to form the LCD100. The location118is for signal input.

For the conventional LCD100inFIG. 1, the light module112is composed by several lamp units, such as the cold cathode fluorescent lamps (CCFLs). All of the lamp units are assembled together as an integrated light module. If one of the lamp units is damaged and needs to be changed, then it is necessary to replace the whole light module. This causes the high cost in maintenance. In order to solve this issue, another design of the light module is allowing each lamp unit to be individually control in power and therefore each the lamp unit can be individually replaced.

FIG. 2is a drawing, schematically illustrating another LCD with the light module having several replaceable lamp units. InFIG. 2, the bezel frame102and the displaying cell assembly of the LCD are shown. Then, the backlight module is composed of several lamp units200. Each lamp units200can be separately controlled in power and replaceable.

The design of light module inFIG. 2still has the disadvantages. The design ofFIG. 2allows each lamp unit200to be replaceable, so that it is not necessary to replace the whole light module. However, since the luminance (brightness) of the lamp is usually reducing according to the total operation time of the lamp, the newly replaced lamp unit usually has the stronger luminance than the luminance of the other lamp units.

This phenomenon is described inFIG. 3. InFIG. 3, when a new lamp unit302replaces the old lamp at the region304in the display area300, the distribution of the luminance is schematically shown in the right drawing. As one can see, the luminance (Lum) at the region304is larger. For the actual displayed image, a brighter stripe in the display screen would appear. This non-uniform luminance causes the poor quality for the displayed image. Particularly, the defect lamp unit to be replaced usually has been operated for a long time period. In this situation, the luminance for the other old lamp units has been significantly reduced. At this moment, the luminance levels between the other old lamp units and the newly added lamp unit have been quite different. This then causes the poor image quality.

The design to solve the foregoing conventional issues is still in need by the manufacturers.

SUMMARY OF THE INVENTION

The invention provides a light module, which can be used in a panel display to serve as a backlight module. The light module allows the individual lamp unit to be replaced with a new one and the luminance of the newly-replaced lamp unit can be automatically or manually adjusted to get a uniform luminance.

The invention provides a light module, which is suitable for use in a display to serve as a light source. The light module, for example, comprises a plurality of lamp units. In addition, a control unit is implemented with an information of a first relation curve of a lamp luminance versus a using time and a second relation curve of the lamp luminance versus an operation current-power. A clocking unit is used to accumulate a total using time for the light module when it is turned on. A power-control providing unit is coupled with the control unit and respectively supplies a current-power to each one of the lamp units. Wherein, for an individual replaced lamp unit, an individual current-power is adjusted in the power-control providing unit to produce a substantially equal luminance with the other lamp units, according to the total using time, the first relation and the second relation.

In another aspect of the present invention, the foregoing power-control providing unit can include an automatic luminance adjustment unit, coupled with the control unit in operation. Also and, a power inverter is coupled between the lamp units and automatic luminance adjustment unit for respectively providing the current-power to each one of the lamp units.

In another aspect of the present invention, the power-control providing unit can further comprise a manual luminance adjustment unit, for allowing a manual adjustment by a user.

In another aspect of the present invention, the present invention provides a luminance adjusting device, for automatically adjusting luminance of lamp unit according to an expected total using time. The luminance adjusting device comprises a storing unit, for storing a first relation of a lamp luminance versus a using time and a second relation of the lamp luminance versus an operation current-power. An input unit is used for inputting the expected total using time for a lamp unit. A power-control providing unit is coupled with the storing unit and the input unit, so as to determine a desired current-power for the lamp unit, and further for producing a desired lamp luminance.

The present invention also provides a method for managing luminance in a light module. The light module includes a plurality of lamp units, and each of the lamp units has an individual current-power being supplied.

The method for managing luminance comprises implementing the information of a first relation of a lamp luminance versus a using time and a second relation of the lamp luminance versus an operation current-power. Then, a total using time for the light module is accumulated. The lamp units have a present luminance at the present time with respect to the total using time. A desired lamp luminance is determined according to the total using time in first relation. A desired current-power is determined according to the desired lamp luminance in the second relation. Then, the current-power is applied to a specific one of the lamp units. As a result, when the specific one of the lamp units is used to replace an old lamp unit, the specific one has the desired luminance substantially equal to the present luminance.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

As described inFIG. 3, the conventional light module at least has the disadvantage of non-uniform luminance in the display area when a lamp unit is replaced with a new one. The present invention has proposed a novel design of the light module to at least solve the foregoing conventional issues. An embodiment is provided as the example for descriptions but does not limit the present invention.

The light module, such as a backlight module or a lamp module, basically includes a plurality of lamp units and a control structure. For example, the lamp units are shown inFIG. 2. However, each lamp unit can include a single lamp or multiple lamps with a design shape. It is not necessary to be limited to the lamp unit shown inFIG. 2. The control structure is for example shown inFIG. 4, which is a block diagram, schematically illustrating the functional blocks to control the lamp unit, according to a preferred embodiment of the present invention. InFIG. 4, the control structure includes a power-control providing unit406, which can couple with a control unit407and respectively supply a current-power to each one of the lamp units.

The control unit407is implemented with the information of a first relation408of a lamp luminance versus a using time and a second relation410of the lamp luminance versus an operation current-power. The relation information408and410are to be described later inFIGS. 5-6. The relation information408and410basically function as a set of table, so that an expected lamp luminance for a specific lamp unit can be set, according to the total using time of the ambient lamp units. As a result, for example, the newly replaced lamp unit can have about the same luminance as the luminance of the ambient lamp units. In order to know the total using time of the light module, a clocking unit412with a clock signal is used to accumulate the using time when the light module is turned on. According to the total using time, then the first relation408can provide the expected lamp luminance at the present time. Then, the second relation410can determine the needed current-power to produce the expected lamp luminance. The control unit407provides the information of the relation information408and410, and the total using time to the power-control providing unit406. Then, the power-control providing unit406can supply the specific current-power to the specific lamp unit, which is a newly replaced one, for example. The foregoing three parts408,410, and412of the control unit407can be respectively implemented at proper places in the light module. For example, the control unit407can also be integrated into the power-control providing unit406. The relations408and410can be stored in a storage device, such as a memory. The clocking unit412can be a time counter implements at a proper location in the light module or at proper location depending on the actual design.

Before further descriptions of the control structure inFIG. 4, the relations408and410are described in more detail.FIG. 5is a drawing, schematically illustrating a relation between a lamp luminance versus a using time.FIG. 6is a drawing, schematically illustrating a relation of a lamp luminance versus a current-power. The first relation408can be for example the relation curves with respect to the curves in several different current, applied to the lamp unit, as shown inFIG. 5. The curves can be described by multiple data points in a form of relation table. The other quantities can be obtained by interpolation, fitting, or any proper mathematic method. The lamp luminance at the beginning is set to 100%, for example. Then, for example, after the lamp unit has been operated for 10,000 hours, then, the luminance is expected to be about 80% when a current of 5 mA is applied to the lamp unit. For another curve, such as the current in 6 mA, it is about 77% after using 10,000 hours. In other words, if the light module has been operated for 10,000 hours, the lamp luminance for an individual the lamp unit is expected to the 80% while the lamp unit is applied with a current-power for producing 5 mA. However, a newly replaced one still remains at 100%. If this newly replaced one is not adjusted, then the conventional phenomenon inFIG. 3occurs. In the invention, the clocking unit412can provide the total using time of the light module, and the present luminance can be simply determined by the relation information408, which can be a table.

InFIG. 6, taking the situation with the operation current by 6 mA as the example, the changing rate of luminance of the lamp unit is varying with the current applied to the lamp unit. In accordance with the result fromFIG. 5, for the new lamp unit, if the luminance of 77% of original is desired, then the current of about 4.3 mA should be applied to the light module, when the light module has been operated for about 10,000 hours. In other words, the original old lamp units, which have been operated for 10,000 hours, are applied with a current of 6 mA while the newly replaced lamp unit is applied by a current of about 4.3 mA. As a result, all lamp units of the light module are about the same in luminance. This is the mechanism of the present invention to adjust the luminance. Several curves like the one inFIG. 6in different operation currents are respectively set up as another curves in the relation table.

In general, the information inFIG. 5andFIG. 6are implemented by the relation tables, which can be stored in a memory device, which is located in a proper place in the light module or an external storage location. This depends on the actual design.

Referring toFIG. 4again, the power-control providing unit406is coupled with the control unit407to obtain the information to determine the desired current-power to apply to the specific lamp unit, which for example is a newly replaced one. The power-control providing unit406can include an automatic luminance adjustment unit402coupled with the control unit407in operation. A power inverter400is coupled between the lamp units (not shown inFIG. 4) and the automatic luminance adjustment unit402for respectively providing the current-power to each one of the lamp units. For the specific replaced lamp unit, a specific current-power is applied. Here, current-power means, for example, an operation voltage, which can produce the desired current to thereby produce the luminance. Based on the design principle described by the present invention, the actual implementation can be done by the person ordinary skilled in the art. For example, the automatic luminance adjustment unit402and the control unit407are integrated together. The power inverter400is under control by the automatic luminance adjustment unit402to provide the required current-power to the lamp.

In addition, the power-control providing unit406can also include a manual luminance adjustment unit404, which can be operated with manual operation by a user. The user can adjust the lamp luminance for the selected lamp unit via a lamp selection unit414, a manual adjusting unit416, and an interface unit418. The lamp selection unit414allows the user to select the specific lamp unit. The user applies a current-power to the selected lamp unit by adding or decreasing the quantity via the manual adjusting unit416. As a result, the present invention has the automatic mode and the manual mode in operation. The more detail is described as follows.

FIG. 7is a block diagram, schematically illustrating the functional blocks when an automatic luminance adjustment mode is taken, according to the preferred embodiment of the present invention. The automatic mode can be implemented by the way shown inFIG. 7, based on the design principle inFIG. 4. InFIG. 7, the lamp voltage control device700can include the power-control providing unit406and the two relation tables408and410. In this example, the clocking information702is input to the lamp voltage control device700. The lamp voltage control device700decides the desired voltage and export the information to the voltage adjusting unit710. The voltage adjusting unit710includes a switching unit704to decide the adjustment of increasing voltage or decreasing voltage, which has the corresponding circuit units706and708. As a result, a voltage corresponding to a current is applied to the lamp712. In addition, at least one back-up luminance sensor714can be optionally implemented at a preset location in the lamp units, so as to detect the actual luminance at the specific location. The back-up luminance sensor714feeds the measured signal back to the lamp voltage control device700as a reference for further adjustment. It should be noted that the design inFIG. 7is just an example based on the design principle inFIG. 4.

In addition, for the manual mode as shown inFIG. 8, the LCD panel800can be implemented with the selection device802and the adjustment device804, which can be, for example, located on the LCD panel800.

FIG. 9is a block diagram, schematically illustrating the functional blocks when the manual luminance adjustment mode is taken, according to the preferred embodiment of the present invention. InFIG. 9, the blocks900,908, and910are similar to the blocks700,710, and712inFIG. 7, in which the voltage adjusting unit908also includes the switching unit903and the circuit units904and906. However, the input signal is determined by manual. For example, a standard graphic set912is presented to a user to see. The user914uses the hand and the eye to select and observe the standard graphic set912. The lamp is selected by the lamp selector916, and changes the current-power, based on the eye's observation on the standard graphic set912.

The present invention has provided the embodiment in actual design. Alternatively, the present invention has also provides a method for managing the luminance in a light module. The light module includes, for example, a plurality of lamp units, and each of the lamp units has an individual current-power being supplied. The method for example includes, in step S1000, implementing an information of a first relation table of a lamp luminance versus a using time and a second relation table of the lamp luminance versus an operation current-power. Then, in step S1010, a total using time for the light module is accumulated. At this moment, the lamp units have a present luminance with respect to the total using time. According to the total using time, a desired lamp luminance can be determined from the first relation table, in step S1020. Here, the necessary interpolation from the data points may be necessary. A desired current-power, in step S1030, is then determined, according to the desired lamp luminance in the second relation table. Then, in step S1040, the current-power is applied to a specific one of the lamp units, which is usually the newly replaced one to be selected.

However, if the user wants to adjust the specific one of the lamps, the manual manner can also be adapted as an alternating choice.