Patent Publication Number: US-2007103090-A1

Title: Piezoelectric ignition circuit for lighting fixtures

Description:
FIELD OF THE INVENTION  
      The present invention relates to a piezoelectric ignition circuit for indoor and outdoor lighting fixtures such as fluorescent lamps, lighting bulbs, neon lights and the like and particularly to an ignition circuit that employs the characteristic of high voltage boosting ratio of the piezoelectric transformer to increase the life span, reduce the size, lower the cost and temperature and enhance the luminance of lighting fixtures.  
     BACKGROUND OF THE INVENTION  
      The conventional ignition circuits for indoor and outdoor lighting fixtures such as fluorescent lamps, lighting bulbs, neon lights and the like mostly adopt winding coil transformers and electronic stabilizers. Due to size constraint, the coil number of the winding coil transformers is limited. Moreover, such ignition circuits generally do not include a power factor corrector and the luminance of the lighting fixtures also is constrained. To achieve a greater luminance, the size of the lighting fixtures must be increased to have more space to accommodate the winding coil transformer. Such an approach results in a greater power and higher temperature of the lighting fixtures, their life span suffers. Moreover, the bigger lighting fixtures do not fit in many environments (such as closed wall lamps or ceiling lamps). The fitting lighting fixtures cannot provide sufficient luminance. As a result, the lighting bulbs cannot be used universally on indoor and outdoor lighting fixtures.  
     SUMMARY OF THE INVENTION  
      The primary object of the present invention is to solve the aforesaid disadvantages. The invention aims to be used on indoor and outdoor lighting fixtures such as fluorescent lamps, lighting bulbs, neon lights and the like. It mainly replaces the winding coil transformer and electronic stabilizer used in the conventional lighting fixtures to overcome the occurred shortcomings such as shorter life span, bulky size, higher cost and temperature and lower luminance. The present invention employs a piezoelectric transformer that can boost voltage rapidly, thereby can increase the life span, shrink the size, reduce the cost, lower the temperature and enhance the luminance.  
      The foregoing, as well as additional objects, features and advantages of the invention will be more readily apparent from the following detailed description, which proceeds with reference to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIGS. 1 and 2  are circuit block diagrams of an embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Please refer to  FIGS. 1 and 2  for the circuit block diagrams of an embodiment of the invention. The invention includes a piezoelectric ignition circuit  20  adopted for use on a lighting fixture  30 . It includes a piezoelectric transformer  24  as a power source of a transformed-voltage power to drive the lighting fixture  30  at a rear end. The piezoelectric ignition circuit  20  mainly includes a commutation circuit  21  which receives and transforms an external AC power  10  and outputs DC power. The piezoelectric ignition circuit  20  is located and integrated in the lighting fixture  30  to receive and transform the AC power. The DC power is divided into a high voltage DC power DC 1  and a lower voltage DC power DC 2  generated by flowing through an impedance circuit  211  to be used by a driving IC  22 . The driving IC  22  is driven by the lower DC power DC 2 . The driving IC  22  includes a frequency generation circuit  221  which is corresponding to a resonant frequency of the piezoelectric transformer  24  and outputs ON/OFF signals, and a signal regulation circuit  222  which receives the ON/OFF signals to provide signal level regulation to output a high level signal SI and a low level signal S 2 . The frequency generation circuit  221  is a RC frequency generation circuit to output a pulse-width modulation signal. The signal regulation circuit  222  may be a TOTEM POLE phase regulation circuit to output the high level signal SI and the low level signal S 2  that are in a floating level mode and have a delay time difference. The signal is generated to drive a power ON/OFF circuit  23  at the rear end. The power ON/OFF circuit  23  is a power MOSFET. The power ON/OFF circuit  23  is driven alternately by the delay time difference of the high level signal S 1  and the lower level signal S 2  to determine the ON/OFF time sequence of the high voltage power DC 1  entering the piezoelectric transformer  24 . The piezoelectric transformer  24  receives the high voltage DC power DC 1  and transforms to a required higher voltage power according to the oscillation frequency for the lighting fixture  30  at the rear end.  
      The invention provides a complete installable circuit. The conventional electronic stabilizer and winding coil transformer are replaced by the driving IC  22 , power ON/OFF circuit  23  and piezoelectric transformer  24 . The size is smaller and the fabrication cost is lower. The piezoelectric transformer  24  has a higher voltage boosting ratio and lower temperature. Thus the lighting fixture  30  adopted the piezoelectric ignition circuit  20  of the invention can maintain the rated life span. Moreover, the lighting fixture  30  may also be a gas discharge lamp to generate a greater luminance when driven by the high voltage of the piezoelectric ignition circuit  20  at the same size.  
      While the preferred embodiments of the invention have been set forth for the purpose of disclosure, modifications of the disclosed embodiments of the invention as well as other embodiments thereof may occur to those skilled in the art. Accordingly, the appended claims are intended to cover all embodiments which do not depart from the spirit and scope of the invention.