Patent Publication Number: US-7712915-B2

Title: Emergency light with a rotatable electrical plug

Description:
BACKGROUND OF THE INVENTION 
   1. Field of Invention 
   The invention relates to emergency lights and more particularly to such an emergency light having a rotatable electrical plug and a releasable illumination unit which can be used as a flashlight after removing. 
   2. Description of Related Art 
   Conventionally, an electrical plug is adapted to insert into an outlet (e.g., wall outlet) for obtaining electrical power therefrom. It is typical for an outlet mounted vertically on the wall. Hence, the electrical plug inserted into the outlet is also disposed vertically. It is also possible that an outlet is mounted obliquely on the wall. However, the electrical plug inserted into the outlet is not disposed vertically in this case. Hence, a device, connected to the electrical plug, may be disposed in an unstable orientation and may be easily disengaged from the electrical plug. 
   For overcoming the above problem, numerous suggestions for rotatable electrical plugs have been disclosed in prior patents. For example, U.S. Pat. No. 5,595,503 discloses a rotatable electrical plug and power cord. 
   Further, U.S. Pat. No. 7,220,010 discloses an emergency light. Thus, continuing improvements in the exploitation of emergency light having a rotatable electrical plug are constantly being sought. 
   SUMMARY OF THE INVENTION 
   It is therefore one object of the invention to provide an emergency light having a rotatable electrical plug and a releasable illumination unit which can be used as a flashlight after removing. 
   The above and other objects, features and advantages of the invention will become apparent from the following detailed description taken with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a preferred embodiment of a charging unit of an emergency light having a rotatable electrical plug according to the invention; 
       FIG. 2  is an exploded view of the charging unit of  FIG. 1 ; 
       FIG. 3A  is a front view of the charging unit of  FIG. 1 ; 
       FIG. 3B  is an exploded perspective view of the charging unit of  FIG. 3A  with the first portion of housing removed; 
       FIG. 4A  is a view similar to  FIG. 3A  where the prong support has been rotated clockwise about 90 degrees; 
       FIG. 4B  is an exploded perspective view of the charging unit of  FIG. 4A  with the first portion of housing removed; 
       FIG. 5A  is a view similar to  FIG. 3A  where the prong support has been rotated clockwise about 180 degrees; 
       FIG. 5B  is an exploded perspective view of the charging unit of  FIG. 5A  with the first portion of housing removed; 
       FIG. 6A  is a view similar to  FIG. 3A  where the prong support has been rotated clockwise about 270 degrees; 
       FIG. 6B  is an exploded perspective view of the charging unit of  FIG. 6A  with the first portion of housing removed; 
       FIG. 7  is a longitudinal sectional view of the emergency light according to the invention; 
       FIG. 8  is a detailed circuit representation of the charging unit of  FIG. 7 ; 
       FIG. 9  is a detailed circuit representation of the illumination unit of  FIG. 7 ; and 
       FIG. 10  is a detailed circuit representation of the lamp indicator unit of  FIG. 7 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring to  FIG. 7 , an emergency light  1  in accordance with a preferred embodiment of the invention comprises a charging unit  2 , an illumination unit  3 , and a lamp indicator unit  4 . Each component is discussed in detail below. 
   Referring to  FIGS. 1 to 6  in conjunction with  FIG. 7 , the charging unit  2  comprises a housing  22  and a prong support  23 . The housing  22  comprises an upper first portion  24  and a mated lower second portion  25 . Charging circuitry is mounted in the charging unit  2 . The first portion  24  has a top slot  241  for the illumination unit  3  to releasably fasten therein for charging. The first portion  24  comprises mating members (e.g., posts)  24   a . The second portion  25  comprises corresponding mating members (e.g., hollow cylinders)  25   a . The posts  24   a  are adapted to securely insert into the cylinders  25   a  by snapping so that the first portion  24  and the second portion  25  can be releasably secured together. Alternatively, the mating members  24   a  and the corresponding mating members  25   a  are adapted to threadedly secure together. Both of the above fastenings are well known in the art and a detailed description thereof is therefore deemed unnecessary. 
   The first portion  24  further comprises an arcuate section  242  on the bottom edge, and an arcuate groove  243  disposed in and parallel to the arcuate section  242 . Correspondingly, the second portion  25  further comprises an arcuate section  252  on the top edge, and an arcuate groove  253  disposed in and parallel to the arcuate section  252 . A complete circle is formed by the arcuate sections  242 ,  252  when the first portion  24  and the second portion  25  are secured together. 
   The second portion  25  further comprises a stop member  251  provided proximate the center of the arcuate section  252 , and a locking tab  254  provided in the stop member  251 . The locking tab  254  and the stop member  251  are either formed integrally or formed separately. The prong support  23  comprises a circular prong support plate  231  having an annular flange  232  on the edge. The prong support  23  is retained in the circle formed by the arcuate sections  242 ,  252  when the first portion  24  and the second portion  25  are secured together. Moreover, the prong support  23  is adapted to rotate in the circle because the flange  232  is rotatably retained in another circle formed by the arcuate grooves  243 ,  253 . 
   A prong assembly  26  is provided distal the housing  22 . The prong assembly  26  comprises a live prong  261 , a neutral prong  262 , and a ground prong  263 . The prongs  261 ,  62 , and  63  are designed to snap into prong receiving apertures (not numbered) which extend through the support plate  231  so that the prongs  261 ,  62 , and  63  can be electrically connected to a flexible electrical coupling means (not shown) which is in turn electrically connected to two receptacles (not shown) in the housing  22 . The receptacles are in turn adapted to electrically connect to a charger plug (not shown) of the illumination unit  3 . The provision of the flexible electrical coupling means permits rotation of the prong support  23  with respect to the housing  22 . The prong assembly  26  is a three-prong version. It is appreciated that a two-prong version is also contemplated by the invention. 
   The support plate  231  further comprises a plurality of (four) equally spaced apart risers  233 ,  234 ,  235 , and  236  (i.e., an angle of any two adjacent ones of the risers  233 ,  234 ,  235 , and  236  is about 90 degrees). Each of the risers  233 ,  234 ,  235 , and  236  has a convex edge facing the housing with a cut  233   a ,  234   a ,  235   a , or  236   a  formed in the center of the convex edge. A stop tab  237  is formed between the risers  233  and  236 . 
   As shown in  FIGS. 3A and 3B , the stop tab  237  is stopped at the right side of the stop member  251 , the riser  233  is adjacent the stop member  251 , and the locking tab  254  is lockingly disposed in the cut  233   a  in an inoperative position of the prong support  23 . Moreover, the live prong  261  and the neutral prong  262  are disposed horizontally with the ground prong  263  disposed therebelow. 
   As shown in  FIGS. 3B ,  4 A, and  4 B, the prong support  23  has been rotated clockwise about 90 degrees with respect to the housing  22 . The locking tab  254  has been deformed flexibly in the rotation due to the nature of its plastic material. As a result, the cut  233   a  rotates to disengage from the locking tab  254  until the riser  234  moves to the stop member  251  with the locking tab  254  lockingly disposed in the cut  234   a . In this position, the neutral prong  262  is disposed above the live prong  261  vertically and the ground prong  263  is disposed therebetween. 
   As shown in  FIGS. 4B ,  5 A, and  5 B, the prong support  23  has been rotated clockwise about 180 degrees with respect to the housing  22 . As a result, the cut  234   a  rotates to disengage from the locking tab  254  until the riser  235  moves to the stop member  251  with the locking tab  254  lockingly disposed in the cut  235   a . In this position, the live prong  261  and the neutral prong  262  are disposed horizontally with the ground prong  263  disposed thereabove. 
   As shown in  FIGS. 5B ,  6 A, and  6 B, the prong support  23  has been rotated clockwise about 270 degrees with respect to the housing  22 . As a result, the cut  235   a  rotates to disengage from the locking tab  254  until the riser  236  moves to the stop member  251  with the locking tab  254  lockingly disposed in the cut  236   a . In this position, the stop tab  237  is stopped at the left side of the stop member  251 . Also, the neutral prong  262  is disposed below the live prong  261  vertically and the ground prong  263  is disposed therebetween. 
   In the embodiment, the stop tab  237  is formed between the risers  233  and  236  so that the prong support  23  is adapted to rotate clockwise to cause the prongs  261 ,  262 , and  263  to rotate clockwise with respect to the housing  22 , and a counterclockwise rotation of the prong support  23  will return the prong support  23  to its inoperative position. 
   Alternatively, in other embodiments the stop tab  237  is formed between the risers  233  and  234  so that the prong support  23  is adapted to rotate counterclockwise to cause the prongs  261 ,  262 , and  263  to rotate counterclockwise with respect to the housing  22 , and a clockwise rotation of the prong support  23  will return the prong support  23  to its inoperative position. 
   It is envisaged by the invention that a rotation of the prong support  23  in the range no more than 270 degrees with respect to the housing  22  is permitted. 
   Referring to  FIGS. 8 to 10  in conjunction with  FIG. 7 , the charging unit  2  is adapted to mate with, for example, a wall outlet to obtain AC (alternating current) power (e.g., 120V AC) therefrom. 
   The illumination unit  3  is shaped as a flashlight and can be used independently as detailed later. A large winding  21  is mounted in the charging unit  2  and a small winding  31  is mounted in the illumination unit  3 . Alternatively, the small winding  31  is mounted in the charging unit  2  and the large winding  21  is mounted in the illumination unit  3 . The large winding  21  is adapted to generate electromagnetic induction by co-acting with the small winding  31  for charging and other purposes as detailed later. 
   Referring to  FIG. 8  specifically, the components of the charging unit  2  are discussed in detail below. The charging unit  2  comprises an input A 22 , a voltage decreasing circuit A 23 , a full-wave rectifier A 24 , a vibration circuit A 25 , and an output A 26 . 
   For example, AC 120V power is supplied from a wall outlet to the input A 22 . And in turn, voltage value of the AC power is decreased by the voltage decreasing circuit A 23  which comprises series connected capacitor C 1  and resistor R 1  and resistor R 9  which is parallel connected to capacitor C 1 . Voltage with decreased value is in turn rectified and filtered by the full-wave rectifier A 24  which comprises a bridge rectifier BR 1  for rectifying purpose and a capacitor C 2  for filtering purpose. The vibration circuit A 25  then generates a vibration signal to the output A 26 . Finally, the vibration signal is sent from the output A 26  to the large winding  21 . The vibration circuit A 25  comprises capacitors C 3 , C 4 , C 5 , resistors R 2 , R 3 , and transistor Q 1 . 
   Referring to  FIG. 9  specifically, the components of the illumination unit  3  are discussed in detail below. The illumination unit  3  comprises a jack J 1 , an electromagnetic induction control circuit  32 , a display control circuit  33 , a half-wave rectifier  34 , a voltage stabilizing circuit  35 , and a lithium battery protection circuit  36 . 
   The small winding  31  is electrically connected to the jack J 1 . AC energy is transferred from the large winding  21  to the small winding  31  when an electromagnetic induction is generated. AC is then rectified by diode D 3  so as to control the cut-off and conduction of transistors Q 3 , Q 4 . And in turn, on, off, and blinking of six light-emitting diodes (LEDs) L 3 , L 4 , L 5 , L 6 , L 7 , and L 8  (see an enlarged view of “LED” on the bottom of  FIG. 9 ) can be controlled by the transistors Q 3 , Q 4  during charging. Preferably, dim, bright, and blinking of the LEDs L 3  to L 8  means inoperative, activation, and abnormal states thereof respectively. 
   The electromagnetic induction control circuit  32  comprises diode D 3 , resistor R 1 , capacitor C 2 , and transistor Q 1 . The display control circuit  33  comprises a switch S 1 , resistors R 2 , R 3 , R 4 , R 6 , capacitor C 5 , transistors Q 3 , Q 4 , an integrated circuit (IC) U 1 , and six LEDs L 3 , L 4 , L 5 , L 6 , L 7 , and L 8 . Note that the number of LEDs can be more or less in other embodiments. 
   Diode D 5  of the half-wave rectifier  34  is for rectifying the AC energy supplied from the jack J 1  to generate DC (direct current). Zener Diode D 1  and capacitor C 1  of the voltage stabilizing circuit  35  are for voltage stabilization and filter. Resistor R 6  of the display control circuit  33  is for limiting voltage value. States of transistors Q 3 , Q 4 , and IC U 1  can be controlled by switching the switch S 1  to on or off by triggering. As a result, on, off, and blinking of the LEDs L 3 , L 4 , L 5 , L 6 , L 7 , and L 8  can be controlled. 
   The lithium battery protection circuit  36  is electrically connected to the display control circuit  33 . The lithium battery protection circuit  36  comprises resistors R 5 , R 7 , R 8 , capacitors C 3 , C 4 , C 6 , and ICs IC 2 , IC 3 . IC IC 2  is for monitoring the charging voltage of a rechargeable lithium battery BAT in order to prevent over voltage or over current (i.e., overcharging) from occurring. Moreover, IC IC 2  is for monitoring whether the lithium battery BAT is too low or a short circuit being occurred during discharge. The IC IC 3  is adapted to disable the circuit for the protection of the lithium battery BAT if any irregularity occurs. 
   An individual may insert the prongs  261 ,  262 , and  263  into, for example, a wall outlet to activate the charging unit  2  for charging the illumination unit  3  by transferring AC energy by electromagnetic induction from the large winding  21  (in the charging unit  2 ) to the small winding  31  (in the illumination unit  3 ). The charging will be stopped when the rechargeable lithium battery BAT is fully charged. The illumination unit  3  will come on automatically to cause the LEDs L 1  to L 6  to emit light as sensed by a sensor (not shown) when experiencing a power outage, i.e., an absence of AC. Further, the sensor can disable the illumination unit  3  when it senses a termination of the activating condition, such as the restoration of AC. Still further, the illumination unit  3  can be removed from the charging unit  2  to be used as a flashlight. Preferably, the LEDs L 3  to L 8  of the illumination unit  3  emit light (i.e., turned on) immediately after removing from the charging unit  2 . Still preferably, the sensor may instruct the LEDs L 3  to L 8  of the illumination unit  3  to stop emitting light (i.e., turned off) immediately after placing the illumination unit  3  in the charging unit  2  and electrically connecting thereto. 
   Referring to  FIG. 10  specifically, the components of the lamp indicator unit  4  are discussed in detail below. The lamp indicator unit  4  is electrically connected to the charging unit  2  and comprises a voltage decreasing circuit  41 , a full-wave rectification circuit  42 , and a lighting module  43 . 
   The voltage decreasing circuit  41  is adapted to decrease voltage value of the supplied AC 120V. Voltage with decreased value is then supplied to full-wave rectifier BR 2  and capacitor C 7  of the full-wave rectification circuit  42  for rectification. And in turn, Zener diode D 1  of the lighting module  43  is adapted to generate a constant DC (e.g., AC 11V). Resistors R 5 , R 6 , R 6 , R 8 , R 10 , switch S 1 , photodiode P 1 , and transistors Q 2 , Q 3  of the lighting module  43  together are adapted to control on, off, and blinking of LEDs L 1 , L 2  as an indication of charging state. Preferably, dim, bright, and blinking of the LEDs L 1 , L 2  represent normal (i.e., not being charged), abnormal, and charging states of the charging unit  2  or the illumination unit  3 . 
   While the invention herein disclosed has been described by means of specific embodiments, numerous modifications and variations could be made thereto by those skilled in the art without departing from the scope and spirit of the invention set forth in the claims.