Abstract:
A detector and method for detecting intensity of ultraviolet (UV) rays are disclosed. The detector has a plurality of UV photo-diodes for detecting intensities of UV rays within different wave bands, an A/D converter for converting analog output signals of the UV photo-diodes into corresponding digital signals, and a micro-controller for controlling operations of the detector. Each of the wave bands overlaps at least one of the other wave bands. The micro-controller calculates the intensity of each overlapped wave band according to the digital signals.

Description:
BACKGROUND OF INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The invention relates to a detection method of an ultraviolet detector, and more particularly, to a method for detecting the intensity of ultraviolet rays in a plurality of wave bands.  
         [0003]     2. Description of the Prior Art  
         [0004]     Please refer to  FIG. 1 .  FIG. 1  is a functional diagram showing a prior art ultraviolet detector. As shown in  FIG. 1 , an ultraviolet ray detector  10  includes a plurality of filters  12 - 18 , a plurality of photodiodes  22 , a plurality of amplifiers  24 , an A/D converter  26  (Analog to Digital Converter, ADC), a processing circuit  28 , a display  30 , a replacement button  32 , and a vibrator  34 . In order to filter out lights within a particular wave band, only lights with certain wavelengths are allowed to pass through each of the filters  12 - 18 . For example, only ultraviolet rays in a wave band of UVA are allowed to pass through the filter  14 , only ultraviolet rays in a wave band of UVB are allowed to pass through the filter  16 , and only ultraviolet rays in a wave band of UVC are allowed to pass through the filter  18 . Essentially, the property of each of the photodiodes  22  is identical and by receiving irradiation from the ultraviolet rays, the photodiodes  22  will produce a corresponding voltage signal or current signal. However, due to the effect of the filters  12 - 18 , each of the photodiodes  22  is only irradiated by lights in a particular wave band. After the irradiation, the signals generated by the photodiodes  22  are transferred to a corresponding amplifier  24  to be magnified. Next, the magnified signals are converted by the A/D converter  26  to a digital signal form that can be processed by the processing circuit  28 . According to the time signal generated by the vibrator  34 , the processing circuit  28  can process the output digital signals generated by the A/D converter  26 . Upon receiving the output digital signals, the processing circuit  28  is also able to calculate the intensity of the ultraviolet rays in each wave band UVA, UVB, and UVC and present the result on the display  30 . In addition, when the replacement button  32  is activated by a user, the detector  10  will be reset to its original state.  
         [0005]     Nevertheless, a much higher cost is generally required for fabricating the prior art detector  10  as many more photodiodes  22  and corresponding filters  12 - 18  are needed. In addition, the prior art also employs a much more complex structure and assembly as each of the photodiodes  22  is required to operate in coordination with the corresponding filter  12 - 18  for detecting the ultraviolet rays in a specific wave band.  
       SUMMARY OF INVENTION  
       [0006]     It is therefore an objective of the present invention to provide an ultraviolet detector with simpler structure for solving the problems caused by the prior art ultraviolet detectors.  
         [0007]     According to the present invention, a method for detecting intensity of ultraviolet rays in a plurality of wave bands comprises the following: utilizing an ultraviolet photo-diode for detecting the ultraviolet rays within a predetermined time; collecting an input signal from the ultraviolet photo-diode after the ultraviolet photo-diode is irradiated by the ultraviolet rays within the predetermined time for calculating a total intensity of the ultraviolet rays; and multiplying the total intensity of the ultraviolet rays by a corresponding ratio of each wave band for calculating the intensity of ultraviolet rays in each wave band.  
         [0008]     The present invention also includes a detector for detecting the intensity of ultraviolet rays, which comprises the following: a plurality of ultraviolet photo-diodes for detecting a plurality of ultraviolet wave bands and generating corresponding analog signals, in which each of the detected wave bands overlaps with at least one of the other detected wave bands; an analog/digital converter electrically connected to the ultraviolet photo-diode for converting analog output signals of the ultraviolet photo-diodes into corresponding digital signals; and a micro-controller electrically connected to the analog/digital converter for controlling the detector and calculating the intensity of ultraviolet rays in each overlapping wave band according to the digital signals converted by the analog/digital converter.  
         [0009]     Finally, the present invention includes a method for detecting intensity of ultraviolet rays in a plurality of wave bands, in which the method comprises the following: utilizing a plurality of ultraviolet photo-diodes for detecting a plurality of ultraviolet wave bands within a predetermined time, in which each of the detected wave bands overlaps with at least one of the other detected wave bands; collecting input signals from the ultraviolet photo-diodes after the ultraviolet photo-diodes are irradiated by the ultraviolet rays within the predetermined time for calculating a total intensity of the ultraviolet rays in each detected wave band; and calculating the ultraviolet intensity in each overlapping wave band of the detected wave bands according to the total intensity of the ultraviolet rays of the detected wave bands and the overlapping condition of each wave band.  
         [0010]     These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. 
     
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0011]      FIG. 1  is a functional diagram showing the prior art ultraviolet detector.  
         [0012]      FIG. 2  is a functional diagram showing the detector of the first embodiment of the present invention.  
         [0013]      FIG. 3  is a relational diagram showing the ultraviolet intensity received by the ultraviolet photo-diodes and its output voltage according to  FIG. 2 .  
         [0014]      FIG. 4  is a functional diagram showing the detector of the second embodiment of the present invention.  
         [0015]      FIG. 5  is a relational diagram showing the relationship between the ultraviolet intensity received by the ultraviolet photo-diode and its output current according to  FIG. 4 .  
         [0016]      FIG. 6  is a flow chart diagram showing the detection process according to  FIG. 2  and  FIG. 4 .  
         [0017]      FIG. 7  is a functional diagram showing the detector of the third embodiment of the present invention.  
         [0018]      FIG. 8  is a functional diagram showing the detector of the fourth embodiment of the present invention.  
     
    
     DETAILED DESCRIPTION  
       [0019]     Please refer to  FIG. 2 .  FIG. 2  is a functional diagram showing the detector  100  of the first embodiment of the present invention. The detector  100  includes an ultraviolet photo-diode  102 , an analog/digital converter  112 , a micro-controller  104 , a display  106 , a replacement button  108 , and a vibrator  110 . The devices are electrically connected and the electrical voltage or current signals are also transmitted among the devices. In contrast to the prior art detector  10 , the detector  100  includes no additional filters and the wave bands detected by the ultraviolet photo-diode  102  are divided into three groups, including UVA, UVB, and UVC. Due to the irradiation of ultraviolet rays, the ultraviolet photo-diode  102  will generate a number of corresponding analog voltage signals. The analog signals are converted by the A/D converter  112  to a digital signal form that can be processed by the micro-controller  104 . After the digital signals converted by the A/D converter  112  are received, the micro-controller  104  will process the signals according to the time signal generated by the vibrator  110  and calculate the intensity of the ultraviolet rays in the wave bands UVA, UVB, and UVC according the digital signals received. After calculation, the result is shown on the display  106 . In addition, when the replacement button  108  is activated by a user, the detector  10  will be reset to its original state.  
         [0020]     After the detector  100  is activated, the ultraviolet photo-diode  102  will detect the ultraviolet rays within a predetermined time. In order to obtain the total intensity of the ultraviolet rays within the predetermined time, the signals output from the ultraviolet photo-diode  102  are first converted by the A/D converter  112  and then collected by the micro-controller  104 . Next, the total intensity of the ultraviolet rays obtained is multiplied separately by a corresponding fixed ratio of each of the wave bands UVA, UVB, and UVC via the micro-controller  104  in order to calculate the intensity of the ultraviolet rays in each wave band UVA, UVB, and UVC. The fixed ratio is essentially estimated and stored in the micro-controller  104 . For example, if the fixed ratio between the ultraviolet rays and each wave band UVA, UVB, and UVC is 0.2:0.5:0.3 and the total intensity of the ultraviolet rays obtained is 100 mW/cm 2 , then the intensity of the ultraviolet rays in each wave band UVA, UVB, and UVC will be 20 mW/cm 2 , 50 mW/cm 2 , and 30 mW/cm 2 .  
         [0021]     It should also be noted that the micro-controller  104  is suitable for detecting a stable light source such as daylight as the ultraviolet intensity is calculated by the micro-controller  104  in different wave bands according to a fixed ratio. Hence, due to its relatively simple circuit layout, the detector  100  can be installed into numerous devices such as cellular phones or watches for detecting the ultraviolet intensity of daylight at any time of the day.  
         [0022]     Please refer to  FIG. 3 .  FIG. 3  is a relational diagram showing the ultraviolet intensity received by the ultraviolet photo-diodes and its output light voltage according to  FIG. 2 . As shown in  FIG. 3 , the relationship between the amount of ultraviolet intensity received by the ultraviolet photo-diode  102  and its output light voltage is a one to one relationship. By utilizing this relationship, the micro-controller  104  is able to calculate the ultraviolet intensity received by the ultraviolet photo-diode  102 .  
         [0023]     Please refer to  FIG. 4 .  FIG. 4  is a functional diagram showing the detector of the second embodiment of the present invention. Similar to the detector  100 , detector  200  also includes an ultraviolet photo-diode  202 , an analog/digital converter  212 , a display  206 , a replacement button  208 , and a vibrator  210  and these devices essentially perform similar functions as the ultraviolet photo-diode  102 , A/D converter  112 , display  106 , replacement button  108  and the vibrator  110 . As stated previously, the detector  100  detects the intensity of the ultraviolet rays according to the light voltage generated after the ultraviolet photo-diode  102  is irradiated by the ultraviolet rays. In contrast to the detector  100 , detector  200  detects the intensity of ultraviolet rays according to the light current generated when the ultraviolet photo-diode  102  is irradiated by the ultraviolet rays. The detector  200  also includes an amplifier  214  for magnifying and transmitting the electric signals output from the ultraviolet photo-diode to a current/voltage converter  216 . After the current signals are converted to voltage signals, the A/D converter  214  will convert the magnified electric current signals to corresponding digital signals and pass the converted signals to the micro-controller  204 .  
         [0024]     Please refer to  FIG. 5 .  FIG. 5  is a relational diagram showing the relationship between the ultraviolet intensity received by the ultraviolet photo-diode and its output light current. As shown in  FIG. 5 , the relationship between the amount of ultraviolet intensity received by the ultraviolet photo-diode  202  and its output light current is a one to one relationship. By utilizing this relationship and multiplying the total ultraviolet intensity by a fixed ratio, the micro-controller  204  is able to calculate the ultraviolet intensity received by the ultraviolet photo-diode  102  in each wave band UVA, UVB, and UVC. Similar to detector  100 , the detector  200  is also suitable for detecting a stable ultraviolet ray source such as daylight.  
         [0025]     Please refer to  FIG. 6 .  FIG. 6  is a flow chart diagram showing the detection process according to  FIG. 2  and  FIG. 4 . The detection process includes the following steps:  
         [0026]     Step  300 : turn on the power to activate the detector  100  or  200 ;  
         [0027]     Step  302 : the ultraviolet photo-diode  102  or  202  receives irradiation from the ultraviolet rays;  
         [0028]     Step  304 : the ultraviolet photo-diode  102  or  202  generates a light voltage or current;  
         [0029]     Step  306 : the A/D converter  112  or  212  converts the analog signals of light voltage or light current to digital signals and the output analog signals output by the ultraviolet photo-diode  202  of the detector  200  are magnified by the amplifier  214 ;  
         [0030]     Step  308 : the micro-controller  104  or  204  receives the digital signal, collects the input signal from a determined time interval and grounds the two ends of the ultraviolet photo-diode  102  and  202  at the end of each time interval for balancing the internal electric charge of the ultraviolet photo-diode  102  or  202 . By doing so, the detected result is not likely to be affected by the previous result when the detector  100  or  200  is reactivated;  
         [0031]     Step  310 : the micro-controller  104  or  204  utilizes equations to calculate the ultraviolet intensity at each time interval (according to the fixed ratio stated above), interconnects with on-board memories, calculates the amount of ultraviolet rays accumulated, and finally passes all data to the display  106  or  206 ; and  
         [0032]     Step  312 : after the display  106  or  206  shows the intensity of ultraviolet rays, related messages, and the amount of ultraviolet rays accumulated, step  302  is repeated until the detector  100  or  200  is turned off.  
         [0033]     Please refer to  FIG. 7 .  FIG. 7  is a functional diagram showing the detector of the third embodiment of the present invention. Similar to the detector  100 , detector  400  detects the intensity of the ultraviolet rays according to the light voltage generated after the ultraviolet photo-diode is irradiated by the ultraviolet rays. The detector  400  also includes an A/D converter  422 , a display  416 , a replacement button  418 , and a vibrator  420 . These devices function in a similar fashion as the A/D converter  112 , the display  106 , the replacement button  108 , and the vibrator  110  of the detector  100 . In contrast to the detector  100 , the detector  400  includes a plurality of ultraviolet photo-diodes  402 ,  404 , and  406  for detecting ultraviolet rays of different wave bands and the micro-controller  414  of the detector  400  also calculates the intensity of ultraviolet rays differently compared to the micro-controller  104 . Despite the fact that the ultraviolet photo-diodes  402 ,  404 , and  406  will produce corresponding light voltage from the ultraviolet irradiation, the detectable wave bands of each diode however are likely to vary due to different composition of the diodes.  
         [0034]     According to the third embodiment of the present invention, the detectable wave bands for the ultraviolet photo-diode  402  are represented by UVA, UVB, and UVC, in which the detectable wave bands for the ultraviolet photo-diode  404  are UVA and UVB, and the detectable wave band for the ultraviolet photo-diode  406  only is UVA. Hence the detectable overlapping wave band for the ultraviolet photo-diodes  402 - 406  is UVA and the detectable overlapping wave bands for the ultraviolet photo-diodes  402  and  404  are UVA and UVB. In order to obtain the intensity of ultraviolet rays in each wave band UVA, UVB, and UVC, the micro-controller  414  first calculates the ultraviolet intensity in UVA according to the light voltage signal output from the ultraviolet photo-diode  406 , then calculates the total ultraviolet intensity in UVA and UVB according to the light voltage signal output from the ultraviolet photo-diode  404 , and finally subtracts the ultraviolet intensity in UVA from the total ultraviolet intensity in UVA and UVB to obtain the ultraviolet intensity in UVB. In the same fashion, the ultraviolet intensity in UVC can also be obtained according to the output signal generated by the two ultraviolet photo-diodes  402  and  404 . In contrast to the detector  10 , the detector  400  not only lacks a placement of a filter, but also includes the ultraviolet photo-diodes  402 - 406  that are comprised of different materials. As a result, several detectable overlapping wave bands will be observed, and according to the output signal, the ultraviolet intensity in each overlapping wave band can be calculated.  
         [0035]     Please refer to  FIG. 8 .  FIG. 8  is a functional diagram showing the detector of the fourth embodiment of the present invention. Similar to the detector  400 , the detector  500  also includes an A/D converter  522 , a display  516 , a replacement button  518 , and a vibrator  520 . These devices function in a similar fashion as the A/D converter  412 , the display  406 , the replacement button  408 , and the vibrator  410  of the detector  400 . In contrast to the detector  400 , the detector  500  essentially determines the ultraviolet intensity in each wave band according to the light current generated by the plurality of ultraviolet photo-diodes  502 ,  504 ,  506  from the irradiation of ultraviolet rays. Despite the fact that the ultraviolet photo-diodes  402 ,  404 , and  406  will produce corresponding light voltage from the ultraviolet irradiation, the detectable wave bands of each diode however are likely to vary due to different composition of the diodes. According to the fourth embodiment of the present invention, the detectable wave bands for the ultraviolet photo-diode  502  are represented by UVA, UVB, and UVC, in which the detectable wave bands for the ultraviolet photo-diode  504  are UVA and UVB, and the detectable wave band for the ultraviolet photo-diode  506  only is UVA. Hence the detectable overlapping wave band for the ultraviolet photo-diodes  502 - 506  is UVA and the detectable overlapping wave bands for the ultraviolet photo-diodes  502  and  504  are UVA and UVB. After magnified by the amplifier  508 , the electrical current signals output from the ultraviolet photo-diodes  502 - 506  will be transmitted to the current/voltage converter  510 . After the current signals are converted to voltage signals, the A/D converter  522  will convert the magnified electric current signals to corresponding digital signals and pass the converted signals to the micro-controller  514 . Similar to the micro-controller  414  from  FIG. 7 , the micro-controller  514  of the detector  500  calculates the ultraviolet intensity of each overlapping wave band according to the overlapping condition of the wave bands of the ultraviolet photo-diodes  502 - 506 .  
         [0036]     In contrast to the detector  100  and  200  that utilizes a fixed ratio for calculating the ultraviolet intensity in different wave bands, the detector  400  utilizes the signals output from the ultraviolet photo-diodes  402 - 406  for calculating the ultraviolet intensity in different wave bands. Hence the usage of the detector  400  is not restricted to a stable light source (such as daylight), but to a much wider range of applications.  
         [0037]     In contrast to the ultraviolet detector from the prior art, the present invention provides a simple and practical ultraviolet detector that is capable of detecting the intensity of ultraviolet rays in various wave bands by utilizing a single ultraviolet photo-diode. In addition, the method for detecting the ultraviolet intensity disclosed by the present invention is also applicable for calculating the ultraviolet intensity in each overlapping wave band by utilizing the ultraviolet photo-diodes comprised with different materials.  
         [0038]     Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.