Patent Publication Number: US-2004051466-A1

Title: Lighting apparatus capable of providing auxiliary and emergency illumination

Description:
BACKGROUND OF THE INVENTION  
       [0001] 1. Field of the Invention  
       [0002] The invention relates to a lighting apparatus, more particularly to a lighting apparatus capable of providing auxiliary and emergency illumination.  
       [0003] 2. Description of the Related Art  
       [0004] Control of a conventional lighting apparatus is usually accomplished via manual control, with or without the use of a remote controller. As such, when it is desired to activate the lighting apparatus during poor ambient light conditions, inconveniences and accidents can arise in view of the need to locate the associated switch or remote controller.  
       [0005] Furthermore, a conventional lighting apparatus for household use usually does not provide emergency illumination in the event of power failure. As such, there is a need to install additional emergency illumination equipments.  
       SUMMARY OF THE INVENTION  
       [0006] The main object of the present invention is to provide a lighting apparatus that can overcome the aforesaid drawbacks associated with the prior art.  
       [0007] Accordingly, a lighting apparatus of this invention comprises a primary power supply, a primary lighting unit, a control unit, a secondary lighting unit, a light sensor, and a back-up power supply.  
       [0008] The primary power supply is adapted to be connected electrically to an electrical outlet. The primary lighting unit is connected to the primary power supply and includes at least one high-power lamp. The control unit is connected to the primary power supply and the primary lighting unit, and is operable so as to control activation of the primary lighting unit. The secondary lighting unit is connected to the control unit, and includes at least one low-power high-intensity light source. The light sensor is connected to the control unit, and generates a light signal corresponding to intensity of ambient light. The back-up power supply is connected to the control unit. The control unit enables operation of the secondary lighting unit when the primary lighting unit is deactivated and the light signal from the light sensor indicates a poor ambient light condition. The control unit further enables supply of power from the back-up power supply to the secondary lighting unit to permit activation of the secondary lighting unit when power failure of the primary power supply occurs. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0009] Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiment with reference to the accompanying drawings, of which:  
     [0010]FIG. 1 is a perspective view showing a preferred embodiment of a lighting apparatus according to the present invention;  
     [0011]FIG. 2 is a schematic circuit block diagram of the preferred embodiment of a lighting apparatus according to the present invention; and  
     [0012]FIG. 3 is a schematic electrical circuit diagram of the preferred embodiment of a lighting apparatus according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
     [0013] Referring to FIGS.  1  to  3 , a lighting apparatus according to the present invention is shown to be embodied in a ceiling lamp that includes a primary power supply  30 , a primary lighting unit  10 , a control unit  20 , a secondary lighting unit  24 , a light sensor  23 , a back-up power supply  22 , a remote controller  40 , and an alarm unit  27 .  
     [0014] The primary power supply  30  is adapted to be connected electrically to an electrical outlet, and is operable so as to generate a DC voltage output (Vdc).  
     [0015] The primary lighting unit  10 , which is conventional in construction, is connected to the primary power supply  30  and includes at least one high-power lamp. In this embodiment, the primary lighting unit  10  includes a number of light bulbs  11  and a night lamp  12 .  
     [0016] The control unit  20  is connected to the primary power supply  30  and the primary lighting unit  10 , and is operable so as to control activation of the primary lighting unit  10 . The remote controller  40  is operably associated with the control unit  20  in a known manner to control operation of the control unit  20 , such as turning on and off each component  11 ,  12  of the primary lighting unit  10 . The control unit  20  includes a microprocessor  21  and a logic circuit  26  connected to the microprocessor  21 . The microprocessor  21  is responsible for controlling activation of the primary lighting unit  10 . The logic circuit  26  is responsible for controlling supply of power from one of the primary and back-up power supplies  30 ,  22  to the secondary lighting unit  24 , which will be described in greater detail hereinafter.  
     [0017] The secondary lighting unit  24  is connected to the logic circuit  26  of the control unit  20 , and includes at least one low-power high-intensity light source  241 . In this embodiment, the secondary lighting unit  24  includes four light sources  241 , each of which is a light emitting diode. The number of the light sources  241  may vary depending upon actual requirements.  
     [0018] The light sensor  23  includes a phototransistor  231 , and is connected to both the microprocessor  21  and the logic circuit  26  of the control unit  20 . The light sensor  23  generates a light signal corresponding to intensity of ambient light detected by the phototransistor  231  and sends the same to the control unit  20 .  
     [0019] The back-up power supply  22  includes a rechargeable battery unit  222 , a charging circuit  221 , and a voltage step-up unit  25 . The battery unit  222  is connected to the logic circuit  26  via the voltage step-up unit  25 , which promotes the battery voltage to a level (Vbat) sufficient for driving the secondary lighting unit  24 , such as +5 volts. The charging circuit  221  is connected to the battery unit  222 , the primary power supply  30  and the microprocessor  21  of the control unit  20 .  
     [0020] To minimize inconvenience when activating the primary lighting unit  10  under poor ambient light conditions, the microprocessor  21  and the logic circuit  26  of the control unit  20  cooperate to enable supply of power, i.e. the DC voltage output (Vdc), from the primary power supply  30  to the secondary lighting unit  24  for operating the secondary lighting unit  24  when the primary lighting unit  10  is deactivated, the light signal from the light sensor  23  indicates a poor ambient light condition, and power failure of the primary power supply  30  does not occur. When the primary lighting unit  10  is activated due to operation of the remote controller  40 , the control unit  20  will deactivate the secondary lighting unit  24 . Moreover, when power failure of the primary power supply  30  occurs, the logic circuit  26  enables supply of power from the back-up power supply  22  to the secondary lighting unit  24  to permit activation of the secondary lighting unit  24  during poor ambient light conditions.  
     [0021] To maintain the stored energy of the battery unit  222  at an appropriate level, the microprocessor  21  activates the charging circuit  221  to initiate charging of the battery unit  222  by the primary power supply  30  upon detection that the battery voltage of the battery unit  222  has dropped below a predetermined threshold. In this embodiment, the battery unit  222  is charged to 95% of the maximum rated voltage, and the predetermined threshold is set to 70% of the maximum rated voltage. The charging circuit  221  includes a first comparator  2211  to detect whether the battery voltage has reached the predetermined threshold, and a second comparator  2213  to detect whether the battery voltage has reached the charging threshold, i.e. 95% of the maximum rated voltage. When the output of the first comparator  2211  indicates that the battery voltage has dropped below the predetermined threshold, the microprocessor  21  will activate the charging circuit  221  to initiate charging of the battery unit  222  by the primary power supply  30 . When the output of the second comparator  2213  indicates that the battery voltage has reached the charging threshold, the microprocessor  21  will deactivate the charging circuit  221 .  
     [0022] To prolong the service life of the rechargeable battery unit  222 , the microprocessor  21  of the control unit  20  further enables periodic activation of the secondary lighting unit  24  when the light signal from the light sensor  23  indicates a bright ambient light condition so as to discharge the rechargeable battery unit  222 . In this embodiment, the discharging cycle is set as one discharging operation per ten charging operations.  
     [0023] The alarm unit  27  is connected to and is controlled by the microprocessor  21  so as to generate an alarm signal upon detection by the microprocessor  21  that the rechargeable battery unit  222  is in a defective state, e.g. the battery voltage has dropped below a defective threshold. In this embodiment, the alarm unit  27  includes a buzzer  272  for generating an audible alarm output, and a drive transistor  271  for interconnecting the microprocessor  21  and the buzzer  272 .  
     [0024] While the lighting apparatus of this embodiment is shown to be in the form of a ceiling lamp, it is apparent to those skilled in the art that the lighting apparatus of this invention may be implemented in the form of another lamp, such as a stand lamp.  
     [0025] Preferably, as best shown in FIG. 3, a serial port  28  is connected to the microprocessor  21 . In view of geographical and time zone differences in different parts of the world, the control operation of the lighting apparatus may require localization. The serial port  28  allows the user to connect the lighting apparatus to a computer (not shown) to establish control settings for the lighting apparatus.  
     [0026] It has thus been shown that the lighting apparatus of this invention combines the function and structure of a conventional lighting apparatus and emergency illumination equipment, thereby resulting in cost and space savings.  
     [0027] While the present invention has been described in connection with what is considered the most practical and preferred embodiment, it is understood that this invention is not limited to the disclosed embodiment but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.