Abstract:
An optical accelerometer including a light source, a light detector and a flexible medium positioned between the light source and the light detector. The flexible medium has an opening through which the light beam from the light sources passes with the light beam being detected by the light detector. Movement by the flexible medium in response to acceleration or deceleration varies the intensity of the light beam detected by the light detector.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention is directed to an optical accelerometer (OA) that generates a change in its electrical signal when the OA experiences any acceleration or deceleration. More particularly the OA is mounted on a platform, (e.g. an automobile) and monitors the acceleration or deceleration of the platform when the platform is in motion. The electrical signal that is generated by the OA is proportional to the amount of acceleration or deceleration the OA experiences. This electrical signal is sent to an electronic controller and the controller processes the signal to perform a specific function such as operating as an electronic switch or potentiometer. 
       BACKGROUND OF THE INVENTION  
       [0002]    There are various types of accelerometers, which perform a similar function as the accelerometer of the present invention including the strain gage and the semiconductor types of accelerometers. All of these accelerometers provide an analog or digital signal proportional to the amount of acceleration or deceleration. However these known accelerometers have the disadvantage of being high cost, complex and are typically unidirectional. 
         [0003]    It is therefore an object of the present invention to provide an accelerometer that is accurate, omni directional (x-y axis), low cost, simple to manufacture and has advantages not possible with prior art accelerometers. 
       SUMMARY OF THE INVENTION  
       [0004]    The present invention comprises an optical accelerometer including a light source, a light detector and a flexible medium positioned between the light source and the light detector. The flexible medium has an opening that permits a light beam from the light source to reach the light detector. When the flexible medium moves or shifts in response to acceleration or deceleration the intensity of the light beam detected by the light detector varies. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0005]      FIG. 1  is a block diagram of the present invention, and 
           [0006]      FIGS. 2-4  illustrate various embodiments of the present invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0007]      FIG. 1  is a block diagram of the OA, platform and electronic controller. The signal generated by the OA is applied to the electronic controller, which in turn is used to operate a device such as an electronic switch or a potentiometer. 
         [0008]    The OA consists of a light source (e.g. light emitting diode (LED)), a light detector (e.g. photo detector), a structure that has two plates (a base plate and a shifting plate) and a flexible medium (e.g. foam, spring) that is attached to the two plates. The plates are used for mounting the light source and light detector with the base plate being mounted on the platform. The light beam that is generated by the light source is directed towards the light detector when the OA is not experiencing any acceleration or deceleration. As long as the light source is mounted on one of the plates and the light detector is mounted on the other plate, it does not matter on which plate they are mounted. The following describes various implementations of the OA. In certain implementations, it is possible to integrate the base plate into the platform and an actual base plate may not be necessary as described below. 
         [0009]    Flexible Medium OA (FMOA) 
         [0010]      FIGS. 2A ,  2 B and  2 C illustrate an implementation of the present invention which uses two plates, (a base plate  20  and a shifting plate  21 ) and a flexible medium  22  (e.g. foam, spring). The flexible medium  22  is used to connect the two plates. On the base plate  20  one of the light devices (e.g. light detector  24 ) is mounted, the base plate  20  is also mounted to a platform  25 . On the shifting plate  21  the other light device (i.e. light source  23 ) is mounted. When the platform  25  experiences any acceleration or deceleration, the shifting plate  21  moves or shifts relative to the platform  25  and base plate  20  and this movement causes the light beam  26  to shift, as shown in  FIG. 2B . This shifting of the light beam  26  causes the amount of light energy, the amount of radiant energy that is being directed to the light detector  24 , to change and this in turn causes a corresponding change in the electrical signal that the light detector  24  produces. The electronic controller then processes this change in this electrical signal.  FIGS. 2A and 2C  are side and top views respectively of this embodiment when it is not experiencing any acceleration or deceleration.  FIG. 2B  is the side view of this embodiment when it is experiencing acceleration or deceleration. 
         [0011]    Flexible Medium with Window OA (FMWOA) 
         [0012]      FIGS. 3A ,  3 B and  3 C illustrate another implementation of the present invention. As in the first embodiment described above, this embodiment has two plates, (a base plate  30  and shifting plate  31 ) and a flexible medium  32  (e.g. foam, spring). Again, the flexible medium  32  is used to connect the two plates. Also, as in the previous implementation, one of the light devices (e.g. light detector  34 ) is mounted on the base plate  30  and the base plate  30  is mounted on a platform  35 . However, this embodiment includes a shifting plate  31  that has a hole or window  38  and a support structure  37  on which the other light device, (i.e. light source  33 ) is mounted. When the platform experiences either acceleration or deceleration, the shifting plate  31  will shift relative to the platform  35  and base plate  30  as shown in  FIG. 3B . When this occurs, the light bean  36  that was passing through the shifting plate window  38  changes. This change in light energy, the amount of radiant energy that is being directed to light detector  34 , changes and this in turn causes a corresponding change in the electrical signal that the light detector  34  produces. The electronic controller then processes this change in this electrical signal.  FIGS. 3A and 3C  are side and top views respectively of this embodiment when it is not experiencing any acceleration or deceleration.  FIG. 3B  is the side view of this embodiment when it is experiencing acceleration or deceleration. 
         [0013]    Flexible Medium with Directional Sensing OA (FMDSOA) 
         [0014]      FIGS. 4A and 4B  illustrate a top and side view of an implementation of the present invention which functions to determine the direction in which the acceleration or deceleration has occurred. With the addition of directional light detectors  47 , either of the OA implementations previously presented, is capable of determining the direction of the acceleration or deceleration. These directional light detectors  47  surround the primary light detector  44  and provide directional information once the primary light detector  44  detects any acceleration or deceleration. The number of directional light detectors  47  will determine the direction&#39;s accuracy of the OA. The more directional light detectors  47  that are used, the higher the directional accuracy. Once the controller senses either acceleration or deceleration through the primary light detector  44 , it then examines the electrical signal from each of the directional light detectors  47 . From this information, the controller is able to determine the direction of the acceleration or deceleration.  FIG. 1  illustrates a block diagram of the OA and the controller mounted on a platform. 
         [0015]    In accordance with the present invention it should be understood that the flexible medium can for example, be polyurethane foam, a spring or any similar material that will react to acceleration or deceleration by movement in a direction opposite to the incident acceleration or deceleration. 
         [0016]    It will be apparent to one skilled in the art related to the present invention that many modification and variations of the present invention are possible in the light of the teachings set forth above. It is therefore to be understood that within the scope of the appended claims the invention may be practiced in various ways other than what is specifically described herein.