Patent Publication Number: US-2012027253-A1

Title: Illumination apparatus and brightness adjusting method

Description:
BACKGROUND 
     1. Technical Field 
     The present disclosure relates to illumination apparatuses; and particularly to a street lamp and a brightness adjusting method used by the street lamp. 
     2. Description of Related Art 
     Light emitting diodes (LEDs) are widely used in many applications, such as in a LED street lamp. However, the LEDs often emit light according to a predetermined current supplied by a constant current source, such that the brightness of the street lamp maintains a constant brightness regardless of any change in traffic. This is an inconvenience. 
     Therefore, there is room for improvement in the art. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Many aspects of the embodiments can be better understood with references to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the embodiments. Moreover, in the drawings, like reference numerals designate corresponding parts throughout three views. 
         FIG. 1  is a block diagram of an illumination apparatus in accordance with one exemplary embodiment. 
         FIG. 2  is a flow chart of a brightness adjusting method in accordance with one exemplary embodiment. 
         FIG. 3  is a flow chart of a brightness adjusting method in accordance with another embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     The disclosure is illustrated by way of example and not by way of limitation in the figures of the accompanying drawings in which like references indicate similar elements. It should be noted that references to “an” or “one” embodiment in this disclosure are not necessarily to the same embodiment, and such references mean at least one. 
     Referring to  FIG. 1 , an illumination apparatus  100  includes a control unit  10 , an image capturing unit  20 , a processor unit  30 , a comparison unit  40 , an adjustment unit  50  and an illumination unit  60 . 
     The control unit  10  is used for generating a start signal and transmitting the start signal to the image capturing unit  20  in a predetermined time. The predetermined time can be adjusted by a user. 
     The image capturing unit  20  is used for capturing a list of the current images of road conditions in response to each start signal and outputs the captured images to the processor unit  30 . In the embodiment, the image capturing unit  20  is a camera set around the illumination unit  60 . 
     The processor unit  30  is used for computing the captured images to obtain a current traffic. In the embodiment, the volume of current traffic is computed based on the size of the captured images. The traffic is in direct proportion to the size or amount of memory required to store the captured images. That is to say, when the traffic increases, the size of the captured images increases, and when the traffic decreases, the size of the captured images decreases. In the other embodiments, the processor unit  30  extracts the edge of the vehicle from the captured images to obtain the number of the vehicles. 
     The comparison unit  40  is used for comparing the current traffic with a predetermined value and generating a control signal according to a comparison result between the current traffic and the predetermined value. In the embodiment, the comparison unit  40  includes a first predetermined value and a second predetermined value, and the first predetermined value is larger than the second predetermined value. If the size of the captured images is at least the first predetermined value, the comparison unit  40  generates a first control signal. If the size of the captured images is between the first predetermined value and the second predetermined value, the comparison unit generates a second control signal. If the size of the captured images is at maximum the second predetermined value, the comparison unit  40  generates a third control signal. The comparison unit  40  includes more than two different predetermined values such as three different predetermined values 1M, 3M and 5M where M represent megabytes. If the size of the captured images is at least 5M, the comparison unit  40  generates a first control signal. If the size of the captured images is between 3M and 5M, the comparison unit  40  generates a second control signal. If the size of the captured images is more than 1M but at most 3M, the comparison unit  40  generates a third control signal. If the size of the captured images is at most 1M, the comparison unit  40  generates a fourth control signal. 
     The adjustment unit  50  is used for generating pulse voltages in response to the control signals. The adjustment unit  50  generates a first pulse voltage in response to the first control signal. The adjustment unit  50  generates a second pulse voltage in response to the second control signal, and the duty cycle of the second pulse voltage is less than that of the first pulse voltage. The adjustment unit  50  stops generating a pulse voltage in response to the third control signal. 
     The illumination unit  60  may be a LED lamp, and is used for emitting light according to the phase voltage of the adjustment unit  50 . 
     Referring to  FIG. 2 , a brightness adjusting method is used to adjust the brightness of the illumination apparatus. The adjusting method includes the following steps. 
     In step S 201 , the control unit generates a start signal in a predetermined time. The predetermined time can adjust by a user. 
     In step S 202 , the image capturing unit captures a list of the current images of the road conditions. 
     In step S 203 , the processor unit processes the captured images to obtain a current traffic. In the embodiment, the traffic is processed based on size of the captured images. The traffic is in direct proportion to the size of the captured images. That is to say, when the traffic increases, the size of the captured images increases, and when the traffic decreases, the size of the captured images decreases. In the other embodiment, the processor unit extracts the contour of the vehicle from the captured images to obtain the number of the vehicles. 
     In step S 204 , it is determined that whether the current traffic is at least a predetermined value. If the current traffic is at least the predetermined value, the comparison unit generates a first control signal and step S 205  is implemented. If the current traffic is less than the predetermined value, the comparison unit generates a second control signal and step S 206  is implemented. 
     In step S 205 , the adjustment unit generates a first pulse voltage according to the first control signal. 
     In step S 206 , the adjustment unit generates a second pulse voltage according to the second control signal. 
     In step S 207 , the illumination unit emits light according to the pulse voltage. 
     Referring to  FIG. 3 , in the other embodiments, the comparison unit comprises a first predetermined value and a second predetermined value and the first predetermined value is larger than the second predetermined value. The step S 301 -S 303  in  FIG. 3  are respectively the same as the step S 201 -S 203  in  FIG. 2 . The adjusting method further comprises the following steps. 
     In step S 304 , it is determined that whether the current traffic is at least the first predetermined value. If the current traffic is at least at the first predetermined value, the comparison unit generates a first control signal and step S 305  is implemented. If the current traffic is less than the first predetermined value, step S 306  is implemented. 
     In step S 305 , the adjustment unit generates a first pulse voltage according to the first control signal and step S 310  is implemented. 
     In step S 306 , it is determined that whether the current traffic is at least at the second predetermined value. If the current traffic is at least at the second predetermined value, the comparison unit generates a second control signal and step S 307  is implemented. If the current traffic is less than the second predetermined value, the comparison unit generates a third control signal and step S 308  is implemented. 
     In step S 307 , the adjustment unit generates a second pulse voltage according to the second control signal and step S 310  is implemented. 
     In step S 308 , the adjustment unit stops generating the pulse voltage according to the third control signal. 
     In step S 309 , the illumination unit stops emitting light. 
     In step S 310 , the illumination unit emits light according to the pulse voltage. 
     Using the above adjusting method, the illumination apparatus can adjust the luminous intensity according to the traffic of the road conditions, thus the life of the illumination apparatus will be increased. 
     It is to be understood, even though information and advantages of the present embodiments have been set forth in the foregoing description, together with details of the structures and functions of the present embodiments, the disclosure is illustrative only; and that changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the present embodiments to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.