Patent Publication Number: US-2006002114-A1

Title: LED lamp with curving cylinder lens

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to light emitting diodes used in devices such as digital still camera modules of portable electronic devices.  
      2. Description of Related Art  
      LEDs (light emitting diodes) were first discovered and publicized in the 1960s. Since that time, and with the benefit of vast improvements in semiconductor wafer technology and encapsulation technology, the lamp efficiency of LEDs has improved exponentially. For red and orange lamps, the lamp efficiency has improved from 1 lm/W (lumen/watt) originally to 100 lm/W. For green lamps, the lamp efficiency has improved from 1 lm/W to 50 lm/W. The lamp efficiency of all LEDs far exceeds that of traditional incandescent bulbs. Moreover, LEDs are smaller, lighter in weight, consume less energy, and have longer lifetimes. LEDs are widely accepted as the light source of choice for household lamps, camera flashlights, traffic lights, automobile headlights, etc.  
      The flashlight source of a camera is usually an LED. A typical flashlight assembly has a lamp set on a baseboard providing power thereto, and a reflective cover set on the baseboard above the lamp to converge the light beams emitted from the lamp. The flashlight assembly has a radiation angle, which should be equal to or greater than the angle of vision of a lens of the camera. Otherwise, edge portions of the photo taken may be dull or darkened. The radiation angle of an LED is relatively large, which makes it hard to converge the intensity of illumination of the LED. If the range of illumination is too large, it may be necessary to increase the power of the LED in order to provide sufficient intensity of illumination within the angle of vision of the lens. However, a high-power LED consumes much electricity.  
      The headlights of an automobile must provide high intensity illumination over a long distance. The range of illumination of a headlight is conventionally configured to be round. However, in practice, upper and lower areas of the range of illumination tend to be unduly bright, and opposite side areas of the range of illumination tend to be relatively dark. Thus when two automobiles approach each other at night, the headlights of each vehicle are liable to cause the driver of the other vehicle to experience glare. Moreover, the relatively poor side illumination may be insufficient for a driver to avoid hazards. Both these problems increase the risk of traffic accidents occurring.  
      A new LED lamp which overcomes the various above-described problems is desired.  
     SUMMARY OF THE INVENTION  
      Accordingly, an object of the present invention is to provide an LED lamp which can converge an intensity of illumination and flatten a range of illumination.  
      To achieve the above object, an LED lamp of a first preferred embodiment of the present invention comprises a baseboard, an LED, a holder, a first converging lens and a cylinder lens. The LED is set on the baseboard, the holder is set on the baseboard surrounding the LED, the first lens is mounted in the holder and located above the LED, and the cylinder lens mounted in the holder above the first lens.  
      Further, an LED lamp of a second preferred embodiment of the present invention comprises a baseboard, an LED, a holder and a curving cylinder lens. The LED is set on the baseboard, the holder is set on the baseboard surrounding the LED, and the curving cylinder lens is mounted in the holder above the LED.  
      Other objects, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which: 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a schematic, cross-sectional view of an LED lamp of the first preferred embodiment of the present invention; and  
       FIG. 2  is a schematic, cross-sectional view of an LED lamp of the second preferred embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      Referring to  FIG. 1 , an LED lamp as an illuminating apparatus in accordance with the first preferred embodiment of the present invention includes a baseboard  10 , a holder  20 , an LED  30  as a light source, a first lens  40 , and a cylinder lens  42 .  
      The baseboard  10  is made of an epoxy resin, and the LED  30  is set on the baseboard  10  and electrically connected therewith. The holder  20  is cylindrical, and defines top and bottom openings. The holder  20  is set on the baseboard  10  surrounding the LED  30 . The first lens  40  is a sub-hemispherical converging lens, and is mounted in an upper portion of the holder  20 . The cylinder lens  42  is mounted in the top opening of the holder  20  above the first lens  40 . The first lens  40  and the cylinder lens  42  are located above the LED  30 , so that light beams emitted from the LED  30  pass through the first lens  40  and the cylinder lens  42 .  
      The spread of angles of the light beams emitted from the LED  30  is reduced by the first lens  40 . The curved surface of the cylinder lens  42  converges light in the direction which is perpendicular to an axis of the cylinder lens  42 . Therefore converged light transmitting from the first lens  40  is further converged relatively closer to the axis of the cylinder lens  42 . Thus, the illumination provided by the LED lamp is concentrated and “flattened.” In  FIG. 1 , the resulting range of illumination on an object surface would be elliptical, with the long axis of the ellipse also being perpendicular to the page.  
      Referring to  FIG. 2 , an LED lamp in accordance with the second preferred embodiment of the present invention includes the baseboard  10 , the holder  20 , the LED  30  and a curving cylinder lens  44 . The curving cylinder lens  44  is mounted in the top opening of the holder  20 , and is located above the LED  30 .  
      In  FIG. 2 , the curving cylinder lens  44  defines an axis. The optical characteristics of the curving cylinder lens  44  are such that it converges all light received from the LED  30 . However, light whose spread direction is perpendicular to the axis is converged more than other light. Thus the illumination provided by the LED lamp is concentrated and “flattened.” In  FIG. 2 , the resulting range of illumination on an object surface would be elliptical, with the long axis of the ellipse also being perpendicular to the page. In other words, the curving cylinder lens  44  of the second embodiment has similar optical characteristics to the combined first lens  40  and cylinder lens  42  of the first embodiment, and provides a similar result to that provided by the combined first lens  40  and cylinder lens  42 .  
      In summary, the unique advantage of the LED lamp of the present invention is that the illumination thereof is more convergent, particularly with respect to one axis of a range of illumination. Thus, for example, when two LED lamps are used as the headlights of an automobile, glare can be reduced and hazards can be more clearly illuminated. This enhances road safety.  
      Although the present invention has been described with specific terms, it should be noted that the described embodiments are not necessarily exclusive, and that various changes and modifications may be made thereto without departing from the scope of the present invention as defined in the appended claims.