Patent Publication Number: US-2012025211-A1

Title: Compact sensor package structure

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a package structure, particularly to a compact sensor package structure. 
     2. Description of the Related Art 
     Sensors and controllers are basic electronics. In sensation, a sensor normally sends a signal, which is normally in form of light, to a detected object; then the signal, which has carried information, is reflected from the detected object back to the sensor for succeeding processing. Refer to  FIG. 1 . Considering difference between the physical characteristics of the elements and optimization the performance thereof, a light source chip  10  and a sensor chip  12  are normally fabricated and packaged respectively and then electrically connected by a printed circuit board  14 , whereby they can detect an object  16 . 
     For example, a conventional distance sensor has two chips. One is an LED (Light Emitting Diode) chip, and the other one is a light sensor chip. The two chips are fabricated independently beforehand and integrated together afterward. Therefore, the conventional distance sensor has complicated assembly procedures, longer fabrication processes and higher fabrication cost. Besides, the conventional distance sensor has merely a single sensor chip and thus can only detect limited distance. Therefore, it is less likely to apply to all consumer electronic products. 
     Accordingly, the present invention proposes a compact sensor package structure to overcome the conventional problems. 
     SUMMARY OF THE INVENTION 
     The primary objective of the present invention is to provide a compact sensor package structure, which has two independent rooms respectively accommodating an LED chip and a sensor chip, and which not only has a smaller volume but also prevents the sensor chip from being interfered with by the light emitted by the LED chip, whereby the present invention has improved performance. 
     To achieve the abovementioned objective, the present invention proposes a compact sensor package structure, which comprises a package body, an LED chip and a sensor chip, wherein the package body has a first room, a second room, a first hole and a second hole, and wherein the first and second rooms are independent to each other, and wherein the first and second holes interconnect the interiors and the external environments of the first and second rooms. The LED chip is arranged inside the first room, corresponding to the first hole and below the first hole. The LED chip projects light through the first hole. The sensor chip is arranged inside the second room, corresponding to the second hole and above/below the second hole. The sensor chip receives light via the second hole. 
     Below, the embodiments are described in detail in cooperation with the attached drawings to make easily understood the characteristics, technical contents and accomplishments of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a sectional view of a conventional sensor package structure; 
         FIG. 2  is a sectional view schematically showing a sensor package structure according to a first embodiment of the present invention; 
         FIG. 3  is a top view schematically showing the sensor package structure according to the first embodiment of the present invention; 
         FIG. 4  is a sectional view schematically showing a sensor package structure according to a second embodiment of the present invention; and 
         FIG. 5  is a top view schematically showing the sensor package structure according to the second embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Below is described a first embodiment according to the present invention. Refer to  FIG. 2  and  FIG. 3 . The compact sensor package structure of the present invention comprises a package body  18 , an LED chip  20  and a sensor chip  22 . The package body  18  has a first room  24  and a second room  26 , which are independent to each other. The package body  18  also has a first hole  28  and a second hole  30 . The first hole  28  interconnects the interior and the external environment of the first room  24 . The second hole  30  interconnects the interior and the external environment of the second room  26 . The second hole  30  is an opening for receiving and focusing light. The second hole  30  is only for receiving a light having a specified range of wavelengths and coming from a specified range of reflective angles lest noise interfere with the sensor chip  22 . The inner surface of the first room  24  has a very smooth focusing reflection layer  32 . The LED chip  20  is arranged inside the first room  24 , corresponding to the first hole  28  and below the first hole  28 . The focusing reflection layer  32  focuses the scattered light emitted by the LED chip  20  into a light, and the light is projected through the first hole  28  to an object. The sensor chip  22  is arranged inside the second room  26 , corresponding to the second hole  30  and below the second hole  30 , and the sensor chip  22  receives the light reflected from the object via the second hole  30 . 
     In order to protect the chips, transparent plates  34  are respectively arranged over the first and second holes  28  and  30 . Further, transparent plastic resins  36  are respectively filled into the first and second rooms  24  and  26  to encapsulate the LED chip  20  and the sensor chip  22 . A plurality of I/O pins  38  is arranged along the bottom of the package body  18  for meeting design requirement. 
     To meet design requirement, the transparent plates  34  and the transparent resins  36  can be omitted. 
     The present invention is characterized in packaging an LED chip  20  and a sensor chip  22  in an identical package body  18 . Thereby, the present invention has smaller volume and lower cost. The package body  18  further comprises a base  40  and a sidewall  42 . The base  40  may be in form of a substrate or a metallic lead frame. The sidewall  42  may be made of a plastic material. The base  40  has I/O pins  38  in the bottom thereof. The sidewall  42  rises vertically from the rim of the base  40  and cooperates with the base  40  to form a basin. The base  40  and the sidewall  42  may be fabricated into a one-piece component with an injection-molding process. Alternatively, the sidewall  42  is bonded to the base  40  to form the basin. A cover  44  is arranged over the sidewall  42  to cover the basin. The cover  44  has the first and second holes  28  and  30 . The cover  44  cooperates with the base  40  and the sidewall  42  to form an accommodation space. A separator  46  is arranged in an appropriate position of the accommodation room, whereby the first and second holes  28  and  30  are respectively located at two sides of the separator  46 . The separator  46  is vertically joined to the base  40  and the cover  44 , partitioning the accommodation space into the first and second rooms  24  and  26 . The focusing reflection layer  32  is arranged on the base  40 , the side wall  42  and the separator  46  of the first room  24 . In the first room  24 , the LED chip  20  is arranged on the base  40  and below the first hole  28 . In the second room  26 , the sensor chip  22  is arranged on the base  40  and below the second hole  30 . As the first room  24  and the second room  26  are independent to each other, the LED chip  20  would not interfere with the sensor chip  22  directly. Thereby, the present invention has improved performance. The two transparent resins  36  are respectively filled into the first room  24  and the second room  26  to encapsulate the LED chip  20  and the sensor chip  22 . 
     The LED chip  20  emits scattered light to the focusing reflection layer  32 . The focusing reflection layer  32  reflects the scattered light, and the transparent resin  36  focuses the reflected light to the first hole  28 , and the focused light is projected to an object through the first hole  28  and the transparent plate  34 . The object reflects the projected light. The sensor chip  22  receives the light reflected by the object through the transparent plate  34 , the second hole  30  and the transparent resin  36 . 
     In the first embodiment, the light projection path and the light-receiving path are at the same side. In a second embodiment, the light projection path and the light-receiving path are respectively at opposite sides. Refer to  FIG. 4  and  FIG. 5  for the second embodiment. 
     In the second embodiment, the compact sensor package structure of the present invention comprises a package body  18 , an LED chip  20  and a sensor chip  22 . The package body  18  has a first room  24  and a second room  26 , which are independent to each other. The package body  18  also has a first hole  28  and a second hole  30 . The first hole  28  interconnects the interior and the external environment of the first room  24 . The second hole  30  interconnects the interior and the external environment of the second room  26 . The second hole  30  is only for receiving a light having a specified range of wavelengths and coming from a specified range of reflective angles lest noise interfere with the sensor chip  22 . The inner surface of the first room  24  has a very smooth focusing reflection layer  32 . The LED chip  20  is arranged inside the first room  24 , corresponding to the first hole  28  and below the first hole  28 . The focusing reflection layer  32  focuses the light emitted by the LED chip  20  into a light beam, and the light beam is projected through the first hole  28  to an object. The sensor chip  22  is arranged inside the second room  26 , corresponding to the second hole  30  and above the second hole  30 , and the sensor chip  22  receives the light reflected from the object via the second hole  30 . 
     In order to protect the chips, transparent plates  34  are respectively arranged over the first and second holes  28  and  30 . Further, transparent plastic resins  36  are respectively filled into the first and second rooms  24  and  26  to encapsulate the LED chip  20  and the sensor chip  22 . A plurality of I/O pins  38  is arranged along the bottom of the package body  18  for meeting design requirement. 
     Similarly, the transparent plates  34  and the transparent resins  36  can be omitted to meet design requirement in the second embodiment. 
     In the second embodiment, the LED chip  20  and the sensor chip  22  are also packaged in an identical package body  18  to decrease volume and reduce cost. The package body  18  further comprises a base  40  and a sidewall  42 . The base  40  may be in form of a substrate or a metallic lead frame. The sidewall  42  may be made of a plastic material. The base  40  has the second hole  30 . The base  40  also has I/O pins  38  in the bottom thereof. The sidewall  42  rises vertically from the rim of the base  40  and cooperates with the base  40  to form a basin. The base  40  and the sidewall may be fabricated into a one-piece component with an injection-molding process. Alternatively, the sidewall  42  is bonded to the base  40  to form the basin. A cover  44  is arranged over the sidewall  42  to cover the basin. The cover  44  has the first hole  28 . The cover  44  cooperates with the base  40  and the sidewall  42  to form an accommodation space. A separator  46  is arranged in an appropriate position of the accommodation room, whereby the first and second holes  28  and  30  are respectively located at two sides of the separator  46 . The separator  46  is vertically joined to the base  40  and the cover  44 , partitioning the accommodation space into the first and second rooms  24  and  26 . The focusing reflection layer  32  is arranged on the base  40 , the side wall  42  and the separator  46  of the first room  24 . In the first room  24 , the LED chip  20  is arranged on the base  40  and below the first hole  28 . In the second room  26 , the sensor chip  22  is arranged on the cover  44  and above the second hole  30 . As the first room  24  and the second room  26  are independent to each other, the LED chip  20  would not interfere with the sensor chip  22  directly. Thereby, the present invention has improved performance. The two transparent resins  36  are respectively filled into the first room  24  and the second room  26  to encapsulate the LED chip  20  and the sensor chip  22 . 
     The light projection way and the light receiving way of the second embodiment are similar to those of the first embodiment and will not repeat herein. 
     In conclusion, the present invention features small volume and prevents the sensor chip from being directly interfered with by the light emitted by the light source chip. Therefore, the present invention has improved performance. 
     The embodiments described above are only to exemplify the present invention but not to limit the scope of the present invention. Any equivalent modification or variation according to the characteristics, technical contents or spirit of the present invention is to be also included within the scope of the present invention.