CA1074851A - Solid state device for lighting fluorescent tubes in emergency - Google Patents
Solid state device for lighting fluorescent tubes in emergencyInfo
- Publication number
- CA1074851A CA1074851A CA297,880A CA297880A CA1074851A CA 1074851 A CA1074851 A CA 1074851A CA 297880 A CA297880 A CA 297880A CA 1074851 A CA1074851 A CA 1074851A
- Authority
- CA
- Canada
- Prior art keywords
- oscillator
- transformer
- voltage
- secondary winding
- charger
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J9/00—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting
- H02J9/04—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source
- H02J9/06—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source with automatic change-over, e.g. UPS systems
- H02J9/062—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source with automatic change-over, e.g. UPS systems for AC powered loads
- H02J9/065—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source with automatic change-over, e.g. UPS systems for AC powered loads for lighting purposes
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
- H05B41/14—Circuit arrangements
- H05B41/26—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc
- H05B41/28—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc using static converters
- H05B41/282—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc using static converters with semiconductor devices
- H05B41/285—Arrangements for protecting lamps or circuits against abnormal operating conditions
- H05B41/2851—Arrangements for protecting lamps or circuits against abnormal operating conditions for protecting the circuit against abnormal operating conditions
- H05B41/2853—Arrangements for protecting lamps or circuits against abnormal operating conditions for protecting the circuit against abnormal operating conditions against abnormal power supply conditions
Landscapes
- Business, Economics & Management (AREA)
- Emergency Management (AREA)
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Circuit Arrangements For Discharge Lamps (AREA)
Abstract
SOLID-STATE DEVICE FOR LIGHTING FLUORESCENT
TUBES IN EMERGENCY
ABSTRACT OF THE DISCLOSURE
A device for lighting fluorescent lamps in emergency comprises a push-pull oscillator whose transistors act as an on-off switch to obtain a square wave a.c. voltage from a d.c. source. This a.c. square wave is transformed into various voltages by using a tapped secondary winding on the oscillator transformer. Two small sections of this secondary winding feed the filaments of the tube and a larger section sandwiched between the above two provides the operating voltage for igniting and maintaining the discharge in the fluorescent tube. The remaining portion of the secondary winding is cap-acitively connected to the centre of the primary winding which aids starting of the lamp. The d.c. source is charged by a regulated charger which main-tains the battery fully charged (without overcharging) under normal power supply conditions. A control device substitutes the use of an electro-magnetic or solid-state relay by keeping the oscillations damped whenever the normal power supply is not interrupted.
TUBES IN EMERGENCY
ABSTRACT OF THE DISCLOSURE
A device for lighting fluorescent lamps in emergency comprises a push-pull oscillator whose transistors act as an on-off switch to obtain a square wave a.c. voltage from a d.c. source. This a.c. square wave is transformed into various voltages by using a tapped secondary winding on the oscillator transformer. Two small sections of this secondary winding feed the filaments of the tube and a larger section sandwiched between the above two provides the operating voltage for igniting and maintaining the discharge in the fluorescent tube. The remaining portion of the secondary winding is cap-acitively connected to the centre of the primary winding which aids starting of the lamp. The d.c. source is charged by a regulated charger which main-tains the battery fully charged (without overcharging) under normal power supply conditions. A control device substitutes the use of an electro-magnetic or solid-state relay by keeping the oscillations damped whenever the normal power supply is not interrupted.
Description
4~5~1L
TUBES IN EMERGENCY
DISCLOSURE
BACKGROUND OF` INVENTION-This invention relates to fluorescent lamp emergency lighting device and, more particularly, to a very compact and efficient emergency lighting device which will operate in a very dependable and rapid fashion upon failure of the electric power.
Standby emergency lighting device is normally used in many public buildings, among various other uses. Such devices normally comprise an incandescent lamp which is energized from a storage battery and activated by electromagnetic or solid-state relays upon interruption of electric power.
The storage battery being normally trickle charged when electric supply is not interrupted.
An incandescent lamp is a relatively inefficient source of luminous energy as compared to fluorescent lamp. Emergency lamps using electromagnetic relays for switching may fail to operate at the time of emergency due to relay sticking, corroded contacts, dirty contacts or ice formation between contacts in a cold environment, such as found in Canada. When trickle charging is used, there is a possibility of battery being damaged by over-charging. Further electromagnetic relays cause sparks which coùld be very hazardous in dusty and/or flammable vapour environments, resulting in a possible explosion. This invention overcomes all of the above-mentloned inadequacies.
.
'-The present invention comprises a device for operating a discharge Iamp, such as a fluorescent lampt from a battery upon failure of normal power supply.
~7~35~
A storage battery is kept charged using a regulated charger and is connected across a conventional push-pull oscillator to obtain a square wave a.c. This oscillation is kept damped using a control device when the normal power supply is not interrupted. Otherwise this square wave a.cO is further transformed into various voltages, such as: filament voltage, striking voltage and working voltage, using a tapped secondary winding on the oscillator transformer for lighting the tube. Striking voltage winding is capacitively connected to the centre tap of the primary winding to aid the starting of the fluorescent tube.
BRIEF DESCRIPTIO~ OF THE DRAWIN~-For a better understanding of the present invention, reference may be made to the preferred embodiment, exemplary of the invention, as shown in the accompanying drawings, in which:
~ igure A is a block diagram of a typical fluorescent lighting device of the present invention. Figure B is a circuit diagram for a fluorescent lighti-ng device constructed in accordance with the present invention.
DESCRIPTION OF THE PREF~RRED ~MBOMMENT:
With specific reference to the form of the invention shown in the drawing, in figure A, the fluorescent lamp 10 is a conventional 10, 15, 20 or 40 watts hot cathode type which is to be energized by the secondary winding of the oscillator transformer of inverter 12. The inverter is operated from a storage battery 11 which is maintained in a charged state by a regulated charger 9. When the supply is not interrupted, the inverter is maintained inoperative by a source responsive control device ~. The step-down transformer 5 is common to the regulated charger and the control device.
An optional switch 7 may be included in the circuit to prevent the light from operating on power ~ailure during day-time (when there is enough natural light) or when being transported. An optional test button 6 can be included to test the unit periodicallyO Loss of a.c. supply will remove the reverse blased condition of the oscillator transistors Q1 and Q2' allowing them to conduct alternatingly, thereby operating the lamp. Restoration of a.c. power ~7485~L
supply at any time will damp the oscillation and place the battery on charge.
The regulated charger has an open circuit voltage equal to the open circuit voltage of the fully charged storage battery, thus protecting the battery from being overcharged, at the same time maintaining it at a fully charged condition.
With reference to the circuit diagram as shown in figure B, when the power supply is not interrupted, the storage battery 11, which has an open circuit potential of, for example, 14 volts, is charged through diode D1, resistor R1, indicator lamp I1 and transistor Q3. The output voltage of the series regulator can be adjusted to the desired level by the potentiometer R3.
The section Rw of the charger winding of transformer 5, diode D2, capacitor C1, dropping resistance R2, zenner diode Zl and potentiometer R3 form a shunt regulated reference voltage source which determines the open circuit voltage of the regulated charger. Indicator lamp I1 is a low voltage incandescent bulb which serves as a charging indicator.
A second centre tapped winding Cw of the transformer 5 togèther with diodes D3 and D4, capacitor C4, dropping resistance R5, light emitting diode (LED) and shunt resistance R4 for the LED forms the source sensitive control i devicè, which reverse bias the transistors Q1 and Q2 making them non-conductive when the power supply is not interrupted. The parallel connected LED and resistance R4 is an optionàl indicator to indicate whether the switch 7 is open or closed when the supply is not interrupted. When the supply is interrupted the reverse bias condition from the transistors Q1 and Q2 is removed and now they can act as an ON-OFF switch to obtain a square wave a.c.
from the supply source 11. The transistors are switched ON or OFF alter-natingly by the feedback windings Fb1 and Fb2 of the oscillator transformer T1, one transistor going ON (conducting) while the other goes OFF (non-; conducting), when properly phased. If transistor Q1 is switched ON, Q2 is OFF and the battery voltage is applied to the top half P1, of the primary winding of T1, inducing a constant d ~/dt in the core. When the core is saturated, d ~/dt falls to zero. ~ith d ~/dt = zero, the induced Eeedback voltage must also be zero. At this point, with no base drive on either transistors both transistors are OFF. There is no flux procLucing current in _ ~ _ 3L !3?74~
either section of the primary winding (P1 or P2) and the field now collapses, thus changing the direction of d ~/dt. This reversal of d ~/dt induces a voltage of opposite polarity in the feedback windings (Fb1 and Fb2) of the transformer T1, thus turning ON transistor Q2 and keeping Q1 OFF, and hence the battery voltage is applied to the bottom half P2, of the primary winding of T1. Now d ~/dt is again constant in the negative direction until the core saturatesl completing the cycle of operations, thus producing a square wave a.c.
The secondary of the oscillator transformer T1 consists of a tapped winding of which two small sections Fw1 and Fw2 are connected across the filaments F1 and F2 respectively of the fluorescent lamp 10. The section M, sandwiched in between Fw1 and Fw2, provides the voltage required to ignite and maintain the discharge once the tube has struck~ The section H.T. of the secondary winding is capacitively connected to the centre of the primary winding to aid the striking or starting of the tube. The tube will continue to glow until the power supply is restored or until the battery can no longer supply the required voltage. In a preferred embodiment of the invention a zenner diode Z2 may be connected in series with resistance R6 to protect the battery from over-draining. If the power supply is interrupted the fluor-escent lamp will continue to glow, until the power supply is restored, or until the battery voltage falls below a predetermined level pre-set by the combination of zenner diode Z2 and resistance R6.
TUBES IN EMERGENCY
DISCLOSURE
BACKGROUND OF` INVENTION-This invention relates to fluorescent lamp emergency lighting device and, more particularly, to a very compact and efficient emergency lighting device which will operate in a very dependable and rapid fashion upon failure of the electric power.
Standby emergency lighting device is normally used in many public buildings, among various other uses. Such devices normally comprise an incandescent lamp which is energized from a storage battery and activated by electromagnetic or solid-state relays upon interruption of electric power.
The storage battery being normally trickle charged when electric supply is not interrupted.
An incandescent lamp is a relatively inefficient source of luminous energy as compared to fluorescent lamp. Emergency lamps using electromagnetic relays for switching may fail to operate at the time of emergency due to relay sticking, corroded contacts, dirty contacts or ice formation between contacts in a cold environment, such as found in Canada. When trickle charging is used, there is a possibility of battery being damaged by over-charging. Further electromagnetic relays cause sparks which coùld be very hazardous in dusty and/or flammable vapour environments, resulting in a possible explosion. This invention overcomes all of the above-mentloned inadequacies.
.
'-The present invention comprises a device for operating a discharge Iamp, such as a fluorescent lampt from a battery upon failure of normal power supply.
~7~35~
A storage battery is kept charged using a regulated charger and is connected across a conventional push-pull oscillator to obtain a square wave a.c. This oscillation is kept damped using a control device when the normal power supply is not interrupted. Otherwise this square wave a.cO is further transformed into various voltages, such as: filament voltage, striking voltage and working voltage, using a tapped secondary winding on the oscillator transformer for lighting the tube. Striking voltage winding is capacitively connected to the centre tap of the primary winding to aid the starting of the fluorescent tube.
BRIEF DESCRIPTIO~ OF THE DRAWIN~-For a better understanding of the present invention, reference may be made to the preferred embodiment, exemplary of the invention, as shown in the accompanying drawings, in which:
~ igure A is a block diagram of a typical fluorescent lighting device of the present invention. Figure B is a circuit diagram for a fluorescent lighti-ng device constructed in accordance with the present invention.
DESCRIPTION OF THE PREF~RRED ~MBOMMENT:
With specific reference to the form of the invention shown in the drawing, in figure A, the fluorescent lamp 10 is a conventional 10, 15, 20 or 40 watts hot cathode type which is to be energized by the secondary winding of the oscillator transformer of inverter 12. The inverter is operated from a storage battery 11 which is maintained in a charged state by a regulated charger 9. When the supply is not interrupted, the inverter is maintained inoperative by a source responsive control device ~. The step-down transformer 5 is common to the regulated charger and the control device.
An optional switch 7 may be included in the circuit to prevent the light from operating on power ~ailure during day-time (when there is enough natural light) or when being transported. An optional test button 6 can be included to test the unit periodicallyO Loss of a.c. supply will remove the reverse blased condition of the oscillator transistors Q1 and Q2' allowing them to conduct alternatingly, thereby operating the lamp. Restoration of a.c. power ~7485~L
supply at any time will damp the oscillation and place the battery on charge.
The regulated charger has an open circuit voltage equal to the open circuit voltage of the fully charged storage battery, thus protecting the battery from being overcharged, at the same time maintaining it at a fully charged condition.
With reference to the circuit diagram as shown in figure B, when the power supply is not interrupted, the storage battery 11, which has an open circuit potential of, for example, 14 volts, is charged through diode D1, resistor R1, indicator lamp I1 and transistor Q3. The output voltage of the series regulator can be adjusted to the desired level by the potentiometer R3.
The section Rw of the charger winding of transformer 5, diode D2, capacitor C1, dropping resistance R2, zenner diode Zl and potentiometer R3 form a shunt regulated reference voltage source which determines the open circuit voltage of the regulated charger. Indicator lamp I1 is a low voltage incandescent bulb which serves as a charging indicator.
A second centre tapped winding Cw of the transformer 5 togèther with diodes D3 and D4, capacitor C4, dropping resistance R5, light emitting diode (LED) and shunt resistance R4 for the LED forms the source sensitive control i devicè, which reverse bias the transistors Q1 and Q2 making them non-conductive when the power supply is not interrupted. The parallel connected LED and resistance R4 is an optionàl indicator to indicate whether the switch 7 is open or closed when the supply is not interrupted. When the supply is interrupted the reverse bias condition from the transistors Q1 and Q2 is removed and now they can act as an ON-OFF switch to obtain a square wave a.c.
from the supply source 11. The transistors are switched ON or OFF alter-natingly by the feedback windings Fb1 and Fb2 of the oscillator transformer T1, one transistor going ON (conducting) while the other goes OFF (non-; conducting), when properly phased. If transistor Q1 is switched ON, Q2 is OFF and the battery voltage is applied to the top half P1, of the primary winding of T1, inducing a constant d ~/dt in the core. When the core is saturated, d ~/dt falls to zero. ~ith d ~/dt = zero, the induced Eeedback voltage must also be zero. At this point, with no base drive on either transistors both transistors are OFF. There is no flux procLucing current in _ ~ _ 3L !3?74~
either section of the primary winding (P1 or P2) and the field now collapses, thus changing the direction of d ~/dt. This reversal of d ~/dt induces a voltage of opposite polarity in the feedback windings (Fb1 and Fb2) of the transformer T1, thus turning ON transistor Q2 and keeping Q1 OFF, and hence the battery voltage is applied to the bottom half P2, of the primary winding of T1. Now d ~/dt is again constant in the negative direction until the core saturatesl completing the cycle of operations, thus producing a square wave a.c.
The secondary of the oscillator transformer T1 consists of a tapped winding of which two small sections Fw1 and Fw2 are connected across the filaments F1 and F2 respectively of the fluorescent lamp 10. The section M, sandwiched in between Fw1 and Fw2, provides the voltage required to ignite and maintain the discharge once the tube has struck~ The section H.T. of the secondary winding is capacitively connected to the centre of the primary winding to aid the striking or starting of the tube. The tube will continue to glow until the power supply is restored or until the battery can no longer supply the required voltage. In a preferred embodiment of the invention a zenner diode Z2 may be connected in series with resistance R6 to protect the battery from over-draining. If the power supply is interrupted the fluor-escent lamp will continue to glow, until the power supply is restored, or until the battery voltage falls below a predetermined level pre-set by the combination of zenner diode Z2 and resistance R6.
Claims (5)
1. Device for operating a discharge lamp from a storage battery, said device comprising:
(a) input terminals adopted to be connected across the said storage battery;
(b) a conventional push-pull oscillator connected across the said input terminals and operable to develop square wave voltage in the windings of the said oscillator thereof;
(c) the said conventional push-pull oscillator consists of an oscillator transformer, two oscillator transistors which are switched ON or OFF alter-natingly by a centre-tapped feed back winding of the oscillator transformer;
(d) a secondary winding on the said oscillator transformer consists of a tapped winding of which two small sections provide the cathode heating voltage for the said lamp, a larger section sandwiched in between the said two small sections provides the operating voltage for the said lamp and the remaining portion of the said secondary winding developes the starting voltage which, when connected capacitively to the centre tap of the primary winding of the said oscillator transformer, aids the starting of the said lamp.
(a) input terminals adopted to be connected across the said storage battery;
(b) a conventional push-pull oscillator connected across the said input terminals and operable to develop square wave voltage in the windings of the said oscillator thereof;
(c) the said conventional push-pull oscillator consists of an oscillator transformer, two oscillator transistors which are switched ON or OFF alter-natingly by a centre-tapped feed back winding of the oscillator transformer;
(d) a secondary winding on the said oscillator transformer consists of a tapped winding of which two small sections provide the cathode heating voltage for the said lamp, a larger section sandwiched in between the said two small sections provides the operating voltage for the said lamp and the remaining portion of the said secondary winding developes the starting voltage which, when connected capacitively to the centre tap of the primary winding of the said oscillator transformer, aids the starting of the said lamp.
2. Device as specified in claim 1, where in said input terminals are con-nected to an a.c. main through a regulated charger means to provide a d.c.
supply for charging said battery without overcharging when power supply is available at the said a.c. main.
supply for charging said battery without overcharging when power supply is available at the said a.c. main.
3. Device as specified in claim 2, where in said regulated charger means comprises a charger transformer whose secondary winding is connected across the said input terminals through a diode, an indicator means and a transistor biased by a reference voltage to get the predetermined open circuit voltage for the charger, which are all connected in series and whose open circuit voltage is determined by the said reference voltage obtained from a shunt regulator network and a portion or full of the said secondary winding of the said charger transformer.
4. Device as specified in claim 3, where in a source sensitive control device is connected to one of the said input terminals and the centre tap of the feed back winding of the said oscillator transformer to keep the device specified in claim 1 inoperative by reverse biasing the oscillator transistors when the power supply is available at the said a c. main; where in said source sensitive control device is a regulated or smoothed d.c. power source comprising a rectifier means, an optional LED or incandescent indicator device and another secondary winding on the said charger transformer or an indepen-dent transformer.
5. Device as specified in claim 1, where in a battery overdrain protection means comprising a zenner diode connected in series with any limb of the bias network of the said oscillator to alter the bias conditions of the said oscillator transistors thereby stopping the oscillations, hence the current through the primary of the said oscillator, when the battery voltage falls below a predetermined level.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA297,880A CA1074851A (en) | 1978-02-28 | 1978-02-28 | Solid state device for lighting fluorescent tubes in emergency |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA297,880A CA1074851A (en) | 1978-02-28 | 1978-02-28 | Solid state device for lighting fluorescent tubes in emergency |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1074851A true CA1074851A (en) | 1980-04-01 |
Family
ID=4110877
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA297,880A Expired CA1074851A (en) | 1978-02-28 | 1978-02-28 | Solid state device for lighting fluorescent tubes in emergency |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1074851A (en) |
-
1978
- 1978-02-28 CA CA297,880A patent/CA1074851A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |