Abstract:
A lamp is provided which is suitable for use in low-profile applications. The lamp includes a light source and a lens. The lens includes a first surface opposite a second surface, where the second surface includes an injection surface and the first surface includes a multi-faceted optical element converging towards the injection surface. The light source injects light into the lens via the injection surface and the light refracts through the first surface while total internally reflecting off the first surface and the second surface toward the periphery of the lens.

Description:
BACKGROUND 
       [0001]    The present exemplary embodiments relate generally to lighting. They find particular application in conjunction with low profile lamps, and will be described with particular reference thereto. However, it is to be appreciated that the present exemplary embodiments are also amenable to other like applications. 
         [0002]    A lamp generally includes one or more light sources which may degrade over time and/or with temperature. However, lamps often lack the ability to compensate for and/or provide notice of such degradation. As a result, a lamp may not operate according to specification and/or provide an operator of the lamp with sufficient notice to replace the lamp before failure. 
         [0003]    Further, a lamp generally includes a light emitting face through which light from the one or more light sources is emitted. Typically, it is preferable that light be uniformly emitted from the light emitting face. However, a light emitting face of a lamp is often larger than the light source. As such, uniform distribution of light emitted from the light source can be difficult to achieve. 
         [0004]    One option includes the use of a catadioptric optical system. A catadioptric optical system uses refraction and reflection, usually via lenses (dioptrics) and curved mirrors (catoptrics), to focus light. However, one problem with using a catadioptric optical system is that catadioptric optical systems are generally fairly thick. Therefore, in instances where a low profile lamp is required, it is often difficult to make use of a catadioptric optical system. 
         [0005]    Another option involves using a matrix of light sources spread along the light emitting face of a lamp. Such an option does not rely on an optical system to distribute light from a light source across a light emitting face of a lamp. Rather, it relies on sheer quantity of light sources. However, one problem with using a matrix is that increasing the quantity of light sources adds unnecessary expense, inefficiency, and complexity to a lamp. 
         [0006]    The present disclosure contemplates new and improved systems and/or methods for remedying this and other problems. 
       BRIEF DESCRIPTION 
       [0007]    Various details of the present disclosure are hereinafter summarized to provide a basic understanding. This summary is not an extensive overview of the disclosure and is intended neither to identify certain elements of the disclosure, nor to delineate the scope thereof. Rather, the primary purpose of the summary is to present certain concepts of the disclosure in a simplified form prior to the more detailed description that is presented hereinafter. 
         [0008]    According to one aspect of the present disclosure, a lamp is provided. The lamp includes a light source and a lens. The lens includes a first surface opposite a second surface, where the second surface includes an injection surface and the first surface includes a multi-faceted optical element converging towards the injection surface. The light source injects light into the lens via the injection surface. This light refracts through the first surface while total internally reflecting off the first surface and the second surface toward the periphery of the lens. 
         [0009]    According to another aspect of the present disclosure, a lamp is provided. The lamp includes a light source, a light sensor, and a power supply. The power supply controls light output of the light source based on measured light output from the light sensor. The lamp further includes a lens, where the lens includes a light emitting face. The lens is configured to receive light emitted from the light source and uniformly distribute the received light across the light emitting face using total internal reflection and refraction. The light sensor is disposed on the light emitting face of the lens. 
         [0010]    According to another aspect of the present disclosure, a lens is provided. The lens includes a first surface opposite a second surface, where these surfaces define a waveguide channel. Light directed to the first surface and/or the second surface total internally reflects to a periphery of the lens. The lens further includes an injection surface receiving light from a light source and a multi-faceted optical element opposite the injection surface. The multi-faceted optical element converges toward the injection surface, where light received by the injection surface total internally reflects off the multi-faceted optical element to the periphery of the lens. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    The following description and drawings set forth certain illustrative implementations of the disclosure in detail, which are indicative of several exemplary ways in which the various principles of the disclosure may be carried out. The illustrative examples, however, are not exhaustive of the many possible embodiments of the disclosure. Other objects, advantages and novel features of the disclosure will be set forth in the following detailed description of the disclosure when considered in conjunction with the drawings, in which: 
           [0012]      FIG. 1  is a block diagram of a lamp according to aspects of the present disclosure; 
           [0013]      FIG. 2  is a top plane view of a lamp according to aspects of the present disclosure; 
           [0014]      FIG. 3  is cross sectional view of the lamp of  FIG. 2 ; 
           [0015]      FIG. 4  is a top plane view of a revolved lens according to aspects of the present disclosure; 
           [0016]      FIG. 5  is a cross sectional view of the lens of  FIG. 4 ; and, 
           [0017]      FIG. 6  is an extruded lens according to aspects of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0018]    One or more embodiments or implementations are hereinafter described in conjunction with the drawings, where like reference numerals are used to refer to like elements throughout, and where the various features are not necessarily drawn to scale. 
         [0019]    With reference to  FIG. 1 , a block diagram of a lamp  100  according to aspects of the present disclosure is provided. The lamp  100  may, for example, be a traffic lamp, a lamp employed by the backlight of certain watches, and the like. The lamp  100  may include one or more of a light source  102 , a lens  104 , one or more sensors  106 , a power supply  108 , a memory  110 , a communications unit  112 , a controller  114 , and the like. 
         [0020]    The light source  102  suitably generates light for the lamp  100 . The light source  102  may include one or more types such as guided light (e.g., light guided from optical fibers or other types of light guides); direct electric-powered light emitters (single or cluster), such as electroluminescent sources (LEDs, organic LEDs, polymer LEDS, etc.), gas discharge sources (fluorescent, plasma, etc.), high-intensity discharge sources, lasers, non-linear light sources; and the like. The light source  102  may be selected to control Correlated Color Temperature (CCT), Color Rendering Index (CRI), and other like characteristics of light. 
         [0021]    The lens  104  suitably distributes light from the light source  102  uniformly across a light emitting face of the lamp  100 . As discussed in greater detail below, this may be achieved using a positive lens that works partially on refraction and partially on total internal reflection. In certain embodiments, the lens  100  may occupy at least half the light emitting face and/or the light source  102  may be positioned away from the lens  104  less than ¼ of the radius or focal length of the lens  102 . Further, in certain embodiments, the lens may be treated to increase uniformity, improve lit appearance, and/or reduce glare. Additionally or alternatively, another optical component, such as a diffusing film, may be used to achieve a similar affect. 
         [0022]    The sensors  106  suitably measure one or more operating conditions of the lamp  100 . Operating conditions may include one or more of input voltage, operating temperature, output current and/or voltage to the light source  102 , light output of the light source  102 , and the like. In certain embodiments, the sensors  106  may include a photo-electric transducer, such as a solid-state photo-detector. In such embodiments, the photoelectric transducer can be connected to any surface of the lens  104 . However, a surface with less impact on the optical performance of the lens  104 , typically an outer surface, is preferable. In certain embodiments, the sensors  106  may additionally or alternatively include a thermistor. 
         [0023]    The power supply  108  suitably receives power from an external power source (not shown) and distributes the power to the constituent components of the lamp  100 . The input voltage of the received power may be an alternating current (AC) voltage or a direct current (DC) voltage. In certain embodiments, the power supply  108  may receive commands from the controller  114  and/or an external device (not shown), controlling the distribution of the power. For example, the power supply  108  may receive commands from the controller  114  instructing the power supply  108  as to the output current and/or voltage to provide to the light source  102 . In other embodiments, the power supply  108  may receive a signal from the sensors  106 , such as the photo-electric transducer, and adjust the output current and/or voltage to the light source  102  to maintain a constant light output. 
         [0024]    The power supply  108  suitably includes one or more hardware components for distribution of the power to the lamp  100 . For example, the power supply  108  may include one or more of a rectifier, surge protection circuit, an electromagnetic interference circuit, a switching power supply, a conflict monitor, a fuse, a fuse blowout (FBO) circuit, a power factor correcting power supply, and the like. However, other components, such as software components, are equally amenable. 
         [0025]    The memory  110  suitably stores log data associated with one or more operating conditions in a stateful manner. For example, the memory  110  may store the operating time of the traffic lamp  100 . The memory  110  may include one or more of a magnetic disk or other magnetic storage medium; an optical disk or other optical storage medium; a random access memory (RAM), read-only memory (ROM), or other electronic memory device or chip or set of operatively interconnected chips; and the like. 
         [0026]    The communications unit  112  suitably provides the controller  114  with an interface from which to communicate with other lamps and/or components external to the lamp  100 . For example, the communications unit  112  may allow the lamp  100  to receive commands from an external controller (not shown). The communications unit  112  may communicate with these other lamps and/or components external to the lamp  100  via, for example, a communications network, such as a local area network, wide area network, the Internet, and so on, and/or a data bus, such as I2C, universal serial bus, serial, and so on. 
         [0027]    The controller  114  suitably monitors operating conditions of the lamp  100 . Monitoring may include receiving data pertaining to one or more operating conditions of the lamp  100  from one or more hardware and/or software components comprising the lamp  100 , such as the sensors  106 . The received data may include the present values of operating conditions and/or data necessary to calculate the present values of operating conditions. Monitoring may further include calculating values for one or more operating conditions from the received data and/or determining whether the operating conditions are within acceptable limits based on this received data. As to the determination, values for operating conditions (whether calculated or directly measured) may be compared against thresholds and/or expected values for the operating conditions. If an operating condition falls outside acceptable limits a fault is detected. 
         [0028]    In certain embodiments, the controller  114  may instruct the power supply  108  as to the output current and/or voltage to provide to the light source  102 , so as to account for degradation factors, while monitoring operating conditions of the lamp  100 . Degradation factors reduce the light output of the light source  102  and may include one or more of operating time of the light source  102 , operating temperature of the lamp  100 , and the like. The controller  114  may adjust the power supply output current and/or voltage on the basis of light output of the light source  102  as determined by one of the sensors  106 , such as the photo-electric transducer. Alternatively, the controller  114  may adjust the power supply output current and/or voltage on the basis of a calculated output current and/or voltage. 
         [0029]    A calculated power supply output I out  may be defined as: 
         [0000]        I   out   =I   nom   *f   TH   *f   De ,  (1)
 
         [0000]    where I nom  is the nominal output current to the light source  102 , f TH  is a correction factor adjusting for temperature inside the lamp  100 , and f De  is a correction factor adjusting for the age of the light source  102 . The correction factors may be determined through the use of one or more lookup tables in which correction factors are indexed by present values of operating conditions. A calculated output voltage V out  can similarly be calculated. 
         [0030]    In certain embodiments, the controller  114  may log operating conditions of the lamp  100  while monitoring operating conditions of the lamp  100 . The process of \ogging operating conditions of the lamp  100  may include writing values (calculated or otherwise) of one or more of the operating conditions to the memory  110 . The values of operating conditions may overwrite previously written log data and/or be written as a log entry indexed by time. Logging may be performed when one or more of the operating conditions are determined to fall outside acceptable limits (i.e., a fault is detected). However, other triggers for logging are equally amenable. For example, logging may be performed at periodic intervals as determined by, for example, a timer of the lamp  100 . As another example, logging may be performed right before the lamp  100  goes into an OFF state. 
         [0031]    In certain embodiments, the controller  114  may generate an indication if a fault is detected while monitoring operating conditions of the lamp  100 . For example, if the operating temperature and/or operating time of the lamp  100  exceed certain thresholds the controller  114  may generate an indication. The indication may include generating an indication signal. The indication signal may be provided to a local component of the lamp  100  and/or an external component thereof. Further, the indication signal may be used for one or more of generating an audio and/or visual warning, flashing one or more light sources, enabling a fault light source, and the like. 
         [0032]    The controller  114  may include a digital/electronic processor, such as a microprocessor, microcontroller, graphic processing unit (GPU), and the like. In such embodiments, the controller  114  suitably executes instructions stored on a memory. In certain embodiments, the memory may be the memory  110  of the lamp  100 . In other embodiments, the memory may be local to the controller  114  and one of ROM, EPROM, EEPROM, Flash memory, and the like. The controller  114  may communicate with the memory  110  of the lamp  100  via a digital communications protocol, such as I2C, USB, RS-232, RS-485, 1 Wire, SPI, WiFi, and the like. However, analog communications protocols are equally amenable. The communications protocol may be carried over one or more of a data bus, a communications network, and the like. 
         [0033]    With reference to  FIGS. 2 and 3 , a lamp  200  according to aspects of the present disclosure is provided.  FIG. 2  provides a top plane view of the lamp  200  and  FIG. 3  provides a cross sectional view of the lamp  200  along line  202 . The lamp  200  is a more specific embodiment of the lamp  100  of  FIG. 1 . Therefore, the discussion heretofore is equally amenable to the discussion to follow and components described hereafter are to be understood as paralleling like components discussed heretofore, unless noted otherwise. The lamp  200  may include one or more of a housing  204 , a memory  206 , a light source  208 , a light emitting face  210 , a lens (not shown), one or more sensors  212 , a power supply  214 , a communications unit  216 , a controller  218 , a circuit board  220 , and the like. 
         [0034]    The housing  204  suitably defines the body of the lamp  200 . The housing  204  may provide a mounting structure and/or protection for components of the lamp  200 . Further, the housing  204  may be formed from one or more of a polymeric material, a metallic material, and the like. In certain embodiments, the housing  204  may act as a heat sink to draw heat away from the components of the lamp  200 . 
         [0035]    The memory  206  suitably stores log data associated with one or more operating conditions in a stateful manner. For example, the memory  206  may store the operating time of the traffic lamp  200 . The memory  206  may include one or more of a magnetic disk or other magnetic storage medium; an optical disk or other optical storage medium; a random access memory (RAM), read-only memory (ROM), or other electronic memory device or chip or set of operatively interconnected chips; and the like. 
         [0036]    The light source  208  suitably generates light for the lamp  200 . The light source  208  may include one or more of guided light, such as light guided from optical fibers or other types of light guides; direct electric-powered light emitters (single or cluster), such as electroluminescent sources (LEDs, organic LEDs, polymer LEDS, etc.), gas discharge sources (fluorescent, plasma, etc.), high-intensity discharge sources, lasers, non-linear light sources, and the like. The light source  208  may be selected to control Correlated Color Temperature (CCT), Color Rendering Index (CRI), and other like characteristics of light. 
         [0037]    The light emitting face  210  suitably corresponds to the portion of the lamp  200  out of which light from the light source  208  is emitted. Put another way, the light emitting face  210  may be viewed as the boundary through which light from the light source  208  passes to get to the external environment of the lamp  200 . In certain embodiments, the light emitting face  210  and the light emitting face of the lens may be one and the same. 
         [0038]    The lens suitably uniformly distributes light from the light source  208  across the light emitting face  210  of the lamp  200 . As discussed in detail below, this may be achieved using a positive lens that works partially on refraction and partially on total internal reflection. In certain embodiments, the lens may occupy at least half the light emitting face  210  and/or the light source  208  may be positioned away from the lens less than ¼ of the radius of the lens. Further, in certain embodiments, the lens may be treated to at least one of increase uniformity, improve lit appearance, and reduce glare. Additionally or alternatively, another optical component, such as a diffusing film, may be used to achieve a similar affect. 
         [0039]    The sensors  212  suitably measure one or more operating conditions of the lamp  200 . Operating conditions may include one or more of input voltage, operating temperature, output current to the light source  208 , light output of the light source  208 , and the like. The sensors  212  may include, for example, one or more of a photo-electric transducer (not shown), such as a solid-state photo-detector, a thermal-electric transducer (shown), such as a thermistor, and the like. In certain embodiments, the photo-electric transducer is disposed on the light emitting face of the lens. 
         [0040]    The power supply  214  suitably receives power from an external power source (not shown) and distributes the power to the constituent components of the lamp  200 . In certain embodiments, the power supply  214  may receive commands from the controller  216  and/or an external device (not shown), controlling the distribution of the power. For example, the power supply  214  may receive commands from the controller  216  instructing the power supply  214  as to the output current to provide to the light source  208 . 
         [0041]    The communications unit  216  suitably provides the controller  218  with an interface from which to communicate with other lamps and/or components externals to the lamp  200 . The communications unit  216  may communicate with these other lamps and/or components external to the lamp  200  via, for example, a communications network, such as a local area network, wide area network, the Internet, and so on, and/or a data bus, such as I2C, universal serial bus, serial, and so on. 
         [0042]    The controller  218  suitably monitors operating conditions of the lamp  200 . In certain embodiments, the controller  218  may instruct the power supply  214  as to the output current to provide to the light source  208 , so as to account for degradation factors, while monitoring operating conditions of the lamp  200 . Degradation factors reduce the light output of the light source  208  and may include one or more of operating time of the light source  208 , operating temperature of the lamp  200 , and the like. In other embodiments, the controller  218  may additionally or alternatively log operating conditions, such as operating time, of the lamp  200  to the memory  206  while monitoring operating conditions of the lamp  200 . In other embodiments, the controller  218  may additionally or alternatively generate an indication if a fault is detected while monitoring operating conditions of the lamp  200 . The indication may include generating an indication signal, which may be used to generate an audio and/or visual notification. 
         [0043]    The circuit board  220  suitably provides a mounting point for one or more of the controller  218 , the communications unit  216 , the power supply  214 , the light source  208 , the memory  206 , one or more of the sensors  212 , and the like. Further, the circuit board  220  suitably interconnects the components electrically. In certain embodiments, the circuit board  220  may act as a heat sink for components mounted thereon and/or include a metal core printed circuit board. The circuit board  220  may mount to the housing  204  of the lamp  200  by, for example, mechanical fasteners, glue, tape, epoxy, and the like. 
         [0044]    With reference to  FIGS. 4 and 5 , a revolved lens  400  according to aspects of the present disclosure is provided.  FIG. 4  provides a top plane view of the lens  400 , and  FIG. 5  provides a cross sectional view of the lens  400  along line  402 . The lens  400  is suitably employed within a lamp, such as the lamp  100  of  FIG. 1  and/or the lamp  200  of  FIGS. 2 and 3 . 
         [0045]    The lens  400  may include one or more of a first surface  404 , a second surface  406 , a waveguide channel  408 , a multi-faceted optical element  410 , an injection surface  412 , and the like. As the lens  400  is oriented in  FIG. 5 , the first surface  404  may be viewed as the top surface of the lens  400 , and the second surface  406  may be viewed as the bottom surface of the lens  400 . Further, it is to be appreciated that the first surface  404  and the second surface  406  need not be continuous. For example, as shown, the first surface  404  includes the multi-faceted optical element  410  and the second surface includes the injection surface  412 . 
         [0046]    The first surface  404  and the second surface  406  suitably interact to define the waveguide channel  408 , which may distribute light to the periphery  414  of the lens  400  using total internal reflection. Light suitably refracts through the first surface  404  as it travels to the periphery  414  of the lens  400  via the waveguide channel  408 . In certain embodiments, the light may travel along a line greater than a critical angle for total internal reflection with respect to the first surface  404  and/or the second surface  406 . Further, in certain embodiments, the outer edges of the first surface and the second surface may be coincident. 
         [0047]    Light directed towards the first surface  404  suitably partially reflects off the first surface  404  towards the second surface  406 . Reflection suitably employs both total internal reflection and simple reflection. Further, light directed towards the first surface  404  suitably partially refracts through the first surface  404 . In that regard, it is to be appreciated that the first surface  404  defines the light emitting face of the lens  400 . In certain embodiments, the first surface  404  may include a diffusing treatment to increase uniformity. 
         [0048]    Light directed towards the second surface  406  suitably reflects off the second surface  406  towards the first surface  404 . Reflection suitably employs both total internal reflection and simple reflection. So as to facilitate reflection, the second surface  406  suitably includes a plurality of converging facets, such as a first facet  416 . Suitably, the converging facets, in conjunction with the multi-faceted optical element  410 , are configured to simulate a focal point  417  different than that of the position of the light source. The converging facets may include a plurality of optical surfaces, such as optical surfaces  418 , and a plurality of non-optical surfaces, such as non-optical surfaces  420 . The optical surfaces, in contrast with the non-optical surfaces, may redirect light directed thereto to the first surface  404 , typically via total internal reflection. 
         [0049]    The multi-faceted optical element  410  suitably reflects and refracts light directed thereto. Reflection includes total internal reflection and/or simple reflection. For example, the multi-faceted optical element  410  may total internally reflect a portion of light directed thereto to the second surface  406  and/or the first surface  404  and refract the remainder of light directed thereto away from the lens  400 . To do so, the multi-faceted optical element  410  suitably includes a plurality of cusps formed from a plurality of optical surfaces, such as optical surfaces  424 , and a plurality of non-optical surfaces, such as non-optical surfaces  422 . Light directed to the multi-faceted optical element  410  typically refracts through the non-optical surfaces, and reflects, typically using total internal reflection, off the optical surfaces towards the second surface  406 . 
         [0050]    The multi-faceted optical element  410  may converge towards the second surface  406  and/or be configured in a Fresnel way. The multi-faceted optical element  410  may, but need not, be centrally located within the lens  400  and/or aligned with the center of a light source used in conjunction with the lens  400 . Putting the latter another way, the point of convergence  426  of the multi-faceted optical element  410  may be aligned with the center of the light source. Suitably, the facets are configured to simulate the focal point  417  different than that of the position of the light source. 
         [0051]    The injection surface  412  suitably acts as the receiving area of the lens  400  for light emitted by a light source used in conjunction with the lens  400 . The injection surface  412  may receive light emitted by a light source  428  placed within 25% of the simulated focal distance of the lens  400  for the simulated focal point  417 . Further, the injection surface  412  may include a spherical surface, where a light source is positioned in the center thereof. In certain embodiments, the injection surface  412  may include no optical power. 
         [0052]    With reference to  FIG. 6 , a perspective view of an extruded lens  600  according to aspects of the present disclosure is provided. The lens  600  is suitably employed within a lamp, such as the lamp  100  of  FIG. 1 . As with the lens  400  of  FIGS. 4 and 5 , the lens  600  makes use of a combination of total internal reflection and refraction to uniformly distribute light from a light source across a light emitting face. Further, the cross section of the extruded lens  600  is the same as the cross sectional view of the lens  400  of  FIG. 5 , whereby it is to be appreciated that the lens  600  operates as described in connection with the lens  400  of  FIGS. 4 and 5 . Therefore, in lieu of repeating the discussion of the lens  400  of  FIGS. 4 and 5 , attention is directed to the discussion of the lens  400  of  FIGS. 4 and 5  above. 
         [0053]    The disclosure has been made with reference to preferred embodiments. Obviously, modifications and alterations will occur to others upon reading and understanding the preceding detailed description. It is intended that the preferred embodiments be construed as including all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.