Abstract:
An light device, includes a plurality of first light cells arranged axisymmetrically about an axis; a plurality of second light cells arranged axisymmetrically around the axis; and a controller coupled to a brightness adjust unit, and determines whether to activate the first light cells and second light cells according to a brightness adjust value of the brightness adjust unit, wherein the average distance between the first light cells and the axis is shorter than the average distance between the second light cells and the axis.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority of Taiwan Patent Application No. 100148543, filed on Dec. 26, 2011, the entirety of which is incorporated by reference herein. 
     TECHNICAL FIELD 
     The technical field relates to a light device, and more particularly relates a brightness adjustable LED light devices. 
     BACKGROUND 
     High-powered light-emitting diode (LED) chip technology continues to progress, and LED light sources have been quickly and widely used for various lighting purposes. However, in different lighting purposes, the quality requirements for the light source are not the same. Concerning technological developments of the LED, although efforts have been put into improving brightness, luminous efficiency, color rendering property and color temperature consistency, few have noticed the problem of brightness modulation of the LED. Nowadays LED brightness modulation is achieved by pulse width modulation (PWM). Compared to traditional analog current modulation, the pulse width modulation control method has the advantage to overcome variations of the LED color temperature and wavelength caused by variations of the current, and digital control of the PWM is easier. 
     However, the LED light source generated by pulse width modulation has a flicking problem during the modulation (100 Hz to 1 KHz). When the LED light source is captured by charge-coupled devices (CCDs) or complementary MOSFET (CMOS) image sensors (cross scanning in vertical: 60 Hz, horizontal: 15750 Hz), it is easy to observe that the on-off pattern of the pulse width modulation produces light and dark ripples shown on the display corresponding to the CCD or CMOS image sensor, so the pulse width modulation can not meet the requirements of the scanning frequency. Thus, the image quality on the display is seriously affected. 
     SUMMARY 
     An embodiment of a light device, comprising: a plurality of first light cells, arranged axisymmetrically about an axis; a plurality of second light cells, arranged axisymmetrically about the axis; and a controller, determining whether to activate the first light cells and second light cells according to a brightness adjust value, wherein an average distance between the first light cells and the axis is shorter than an average distance between the second light cells and the axis. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic diagram illustrating an embodiment of a light device; 
         FIG. 2A  is a schematic diagram illustrating an embodiment of light areas arranged as a triangle and triangular rings; 
         FIG. 2B  is a schematic diagram illustrating an embodiment of light areas arranged as a circle and circular rings; 
         FIG. 2C  is a schematic diagram illustrating an embodiment of light areas arranged discretely; and 
         FIG. 3  is a block diagram illustrating an embodiment of a light device. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     The making and using of the embodiments of the present disclosure are discussed in detail below. It should be appreciated, however, that the embodiments provide many applicable inventive concepts that can be embodied in a wide variety of specific contexts. The specific embodiments discussed are merely illustrative of specific ways to make and use the disclosure, and do not limit the scope of the disclosure. 
       FIG. 1  is a schematic diagram illustrating an embodiment of a light device  100 . The light device  100  comprises a controller  110  and a light module  120 . The light module  120  comprises light areas L 1 , L 2  and L 3 , and each of the light areas L 1 , L 2  and L 3  is arranged axisymmetrically about the X-axis or Y-axis. The controller  110  may selectively activate different light areas for adjusting the brightness of the light module  120 . For example, the light module  120  may generate the maximum brightness when the controller  110  activates the light areas L 1 , L 2  and L 3 , the light module  120  may generate the second maximum brightness when the controller  110  activates the light areas L 1  and L 2 , similarly, and the light module  120  may generate the minimum brightness when the controller  110  activates the light area L 1 . Thus, the controller  110  can perform brightness adjusting. In another embodiment, the controller  110  may further comprise a brightness adjust unit  112 , wherein the brightness adjust unit  112  may be any component which can indicate a value, such as a control pad, a variable resistor, and a digital value adjustment unit. Also, the controller  110  may selectively activate different light areas according to the value indicated by the brightness adjust unit  112 . Thus, the controller  110  can perform brightness adjusting via the brightness adjust unit  112 . Note that the relation between the brightness of the light module  120  and the value of the brightness adjust unit  112  is not limited thereto, but based on design of a user, for example, the threshold of the value indicated by the brightness adjust unit  112  can be set, or the smallest value of brightness adjust unit  112  can indicate the maximum brightness of the light module  120 . 
     Refer to the embodiment of  FIG. 1 , wherein each of the light area is not only arranged axisymmetrically about the X-axis or Y-axis, but also arranged axisymmetrically about both the X-axis and Y-axis. In other words, each of the light area is arranged in point symmetry around the intersection point of the X-axis and Y-axis. In the embodiment, the light area may be arranged axisymmetrically about only one axis according to requirements. Although the light areas are arranged as a rectangle and rectangular rings as shown in  FIG. 1 , the light areas still can be arranged as different shapes, and the amount of the light areas can be different according to design. For example, the light module has light areas L 1 ˜L 8  arranged as a triangle and triangular rings as shown in  FIG. 2A , the light module has light areas L 1 ˜L 8  arranged as a circle and circular rings as shown in  FIG. 2B , and the light module has light areas L 1 ˜L 8  arranged axisymmetrically and discretely as shown in  FIG. 2C . In the embodiment of  FIG. 2C , each of the light areas has the same amount of light cells ( 32 ). 
     In the embodiments, a different brightness adjusting scheme with more brightness levels can be achieved based on the arrangement of the light areas L 1 ˜L 3 . Since each of the light area is arranged axisymmetrically, and the light areas are activated in order from the inside to the outside and are deactivated in order from the outside to the inside, stable and uniform light can be produced at each brightness levels, and the brightness may be adjusted to prevent high frequency flicking which occurs when the PWM is used for brightness adjustment. For the PWM that is currently used for adjusting brightness, when the image sensor CCD or CMOS has a scan frequency higher than that of the PWM, the image captured by the image sensor has dark ripples, which causes the image on the display to also have dark ripples, and adversely affects quality of the displayed image on the display. However the effect can be avoided in the embodiment. In addition, the LED cells of the light area can be manufactured by the Thin Film LED Packages (TFP) process, such that the positioning accuracy of die bond is not limited, the gap between the light areas is reduced, and the non-uniform brightness or color of the light area is reduced. It should be noted, in another embodiment, the order of turning light areas on/off is not limited to tuning light areas on from the inside to outside or turning light areas off from the outside to inside, and can be designed according to the application or requirements. 
     In an embodiment, each of the light areas L 1 , L 2  and L 3  of the light module  120  is composed of a plurality of light cells, such as a light cell of a micro-LED array, or a LED cell. In an embodiment, the light cells of the light module  120  may be a multi-chip LED array, and the integrated multi-chip LED array can be produced by the technique of die bond-welding line or a manufacturing process method of AC/HV LED. The LED cell can be produced by the manufacturing process of an LED chip. For example, after the LED cells manufacturing process of the light area on a sapphire substrate having LED epitaxial layer is performed, the sapphire substrate is integrated with a packaged substrate. The integration can be in the form of a flip chip or similar thin-film LED which has only a single-sided electrode junction with the packaged substrate. After the integration is finished, the sapphire substrate is removed by using laser stripping technology (Laser Lift-Off). Thus, independently activated pins of each LED cells can be achieved by the wiring of the packaged substrate. In the case of a similar thin-film LED which has only a single-sided electrode junction with the packaged substrate, independently activated pins of each LED cells can be produced by the transparent electrode and the packaged substrate electrode manufacturing process. 
     In an embodiment, in order to achieve the uniformity of the brightness difference, each of the light areas L 1 , L 2  and L 3  has the same amount of light cells or has the same dimension of lighting area, as shown in  FIG. 2C . Also, due to the light area L 1  being arranged inside of the light area L 2  and the light area L 2  being arranged outside of the light area L 1 , the average distance between the light cells of the light area L 1  and X-axis (or Y-axis) is shorter than the average distance between the light cells of the light area L 2  and X-axis (or Y-axis). 
       FIG. 3  is a block diagram illustrating an embodiment of a light device  300 . The light device  300  comprises a power supply PW, a controller Ctrl, switches SW 1 , SW 2  and SW 3 , linear regulators LR 1 , LR 2  and LR 3 , light area L 1  with light cells L 1 ( 1 )˜L 1 ( m ) connected in series, light area L 2  with light cells L 2 ( 1 )˜L 2 ( m ) connectcd in series, and light area L 3  with light cells L 3 ( 1 )˜L 3 ( m ) connected in series. General speaking, the light cell may be an LED. In an embodiment, the light cells connected in series may be designed according the grid voltage, such that the component with high surge current capability can shrink, and the integration and digitalization can be achieved. The power supply PW provides a driving voltage to the switch SW 1 , the linear regulator LR 1 , and the light cells L 1 ( 1 )˜L 1 ( m ). If the light cells L 1 ( 1 )˜L 1 ( m ) of light area L 1  need to be turned on, the user can transmit an activate signal to the switch SW 1  by the controller Ctrl. When the switch SW 1  turns on, the linear regulator LR 1  generates a fixed current to the light cells L 1 ( 1 )˜L 1 ( m ) according to the driving voltage provided from the power supply PW. Due to the linear regulator LR 1  maintaining the driving of the fixed current within a large range of the working voltage, voltage error caused by the light cells with different driving voltages integrated in the silicon substrate can be overcome. On the other hand, if the light cells L 1 ( 1 )˜L 1 ( m ) of light area L 1  need to be turned off, the user can transmit an inactivate signal to the switch SW 1  by the controller Ctrl. 
     In addition, the switches SW 2  and SW 3 , the linear regulators LR 2  and LR 3 , the light area L 2  with light cells L 2 ( 1 )˜L 2 ( m ) connected in series, and the light area L 3  with the light cells L 3 ( 1 )˜L 3 ( m ) connected in series operate in same way as the switch SW 1 , the linear regulator LR 1 , and the light cells L 1 ( 1 )˜L 1 ( m ). By this, the controller Ctrl can control the on/off states of the light areas L 1 , L 2  and L 3  individually. As described in the embodiment of  FIG. 1 , the light areas are arranged axisymmetrically, and the light areas are activated in order from the inside to the outside and are deactivated in order from the outside to the inside. This allows stable and uniform light to be produced at each brightness level, and the brightness may be adjusted to prevent high frequency flicking which occurs when PWM is used for brightness adjustment. 
     In some embodiments, the switches SW 1 , SW 2  and SW 3  can be MOS-controlled thyristors. Thus, once the switch receives an enable signal (such as high voltage impulse signal), the switch keeps turning on, instead of being provided a continual enable signal, such that the power consumption is reduced. On the other hand, once the turn-on switch receives a disable signal, the switch turns off. 
     In addition,  FIG. 3  merely discloses a simple embodiment of the circuit connection, wherein the light areas L 1 , L 2  and L 3  are still arranged axisymmetrically in this embodiment. Although the embodiment merely discloses three light areas, more light areas can be set and controlled. In an embodiment, the components shown in  FIG. 3  can be integrated in a silicon substrate, and the silicon substrate further is integrated with a protection component. When one of the light cells fails, the protection component can change the current loop to bypass the failed light cell, such that the other light cells can still work. 
     It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the disclosed embodiments without departing from the scope or spirit of the disclosure. In view of the foregoing, it is intended that the disclosure cover modifications and variations of this disclosure provided they fall within the scope of the following claims and their equivalents.