Electric lamp and discharge devices: systems – Periodic switch in the supply circuit – Impedance or current regulator in the supply circuit
Reexamination Certificate
1999-02-08
2001-04-03
Wong, Don (Department: 2821)
Electric lamp and discharge devices: systems
Periodic switch in the supply circuit
Impedance or current regulator in the supply circuit
C315S2090SC, C315SDIG004, C315S225000
Reexamination Certificate
active
06211624
ABSTRACT:
BACKGROUND OF THE INVENTION
Because fluorescent lamps cannot be simply dimmed with a phase control like incandescent lamps, numerous suggestions have been made for reducing the brightness by means of group circuits or other methods in residential or business quarters.
This applies especially to fluorescent compact lamps where the fluorescent lamp with a ballast is inserted in the normal lamp socket and therefore only the two mains supply lines are available for modulating the brightness.
For example, the German patent DE 40 37 948 described an arrangement where the compact lamp is switched to two bi-stable switching conditions by short interruptions of the power supply. This arrangement was used in practice but is not satisfactory because it is not adequately comparable with the function of a continually controllable dimmer.
U.S. Pat. No. 5,068,576 introduced another dimmer switch for a fluorescent lamp where a simple two-wire connection is arranged between the dimmer switch and the fluorescent lamp. The control of the logical circuit is performed via the change of the input voltage of a voltage regulator. A microcomputer influences the voltage amount through digital signals. A phase cutting control was described where complete half waves are cut off from the mains alternating voltage. This entails the disadvantage that the cut half waves cause the fluorescent lamp to flicker when dimmed.
SUMMARY OF THE INVENTION
It is the task of this invention to propose a method for dimming fluorescent lamps that is extremely simple to operate, that has a far simpler arrangement and where the fluorescent lamp is not additionally influenced by the control impulses of the logical circuit.
This invention makes this possible by using an electronic control element as a component of the logical circuit in which the block of the current flow occurs only during the time period when there is no charging current for the downstream current mains supply circuit. This has the advantage that control of the logical circuit do not influence the electric current flowing through the fluorescent lamp. Unwanted influences on the light intensity of the fluorescent lamp by control pulses for the logical circuit are thus avoided.
A preferred embodiment for changing the form of the input voltage is that an electronic circuit element is provided as a component which temporarily blocks the current flow at least after every second zero-crossing of the voltage, depending upon time and/or voltage. This circuit does not influence the current supply of the fluorescent lamp when the current flow block occurs only during the time period in which there is no flow of charging current for the downstream direct-current mains supply circuit.
An impulse generator is suggested as another variant for changing the input voltage form that emits its identification impulses only during the time period when there is no charging current for the downstream direct-current mains supply circuit. This embodiment also insures that the identification impulses do not interfere with the power supply of the fluorescent lamp during the brightness adjustment.
In order to prevent influencing the intensity dimmer during brief mains interruptions below 100 milliseconds as they can occur with lightening strikes, the logical circuit can also be blocked during such mains interruptions.
Because a continual control of the light intensity is not desired in many cases, a logical circuit under this invention can be designed in the manner that the logical circuit controls a gradual reduction of brightness to default brightness levels when the current flow is briefly interrupted for more than 100 milliseconds.
The combination of the two features for controlling the logical circuit, namely providing for a change of the net voltage change and also for a brief interruption of the mains supply, is optionally available, for example, in a single contact lamp. This means an important simplification of such circuits because these dimmer circuits can be directly integrated in the upstream device.
Such dimming cannot reach brightness 0. For this reason, the invention suggests that brightness is again increased after reaching a certain minimum brightness during a longer change of the net voltage.
When full brightness is reattained, the invention provides that even in continued net voltage changes the full brightness is maintained and no further reduction phase of brightness occurs.
This measure is necessary to avoid a stronger decrease and increase of brightness during an unwanted decrease of the net voltage, for example at peak consumption. With the suggested measure, such net behavior would indeed introduce a dimming process which, however, would be leveled after a short period of time.
The change of input net voltage can be accomplished under the invention by installing a touch contact in series with the net circuit that has a normally closed rest contact bridging a component that changes the form and/or the amplitude of the input net voltage.
A resistance is proposed as an alternative form of such a component which changes only the amplitude of the input voltage. A relatively small voltage decrease suffices to trigger the logical circuit so that the voltage decrease in the brief period of activation plays practically no role. But the fluorescent lamp receives less power during the brightness control adjustment so that the adjustment suffers a minor distortion when no voltage control occurs in the direct-current mains supply circuit or in the converter.
To implement the process described above, no complicated dimmer is required as before but rather a touch contact is provided in series with the net circuit containing a normally closed rest contact that bridges a resistance or a simple electronic element.
This is completely adequate to control the logical circuit that can be integrated with the electronic upstream device in a common housing resulting in a contact lamp or a contact lamp adapter, respectively, where a threaded socket or a quarter-turn type connector makes the insertion into a lamp fixture possible.
The fluorescent lamp can be optionally connected firmly with, or plugged into such a compact lamp housing.
It is also recommended to combine the mains switch and the touch contact into one unit or, also, to provide the mains switch directly with an additional rest contact that is formed as a touch contact.
REFERENCES:
patent: 4392086 (1983-07-01), Ide et al.
patent: 4408185 (1983-10-01), Rasmussen
patent: 4414493 (1983-11-01), Henrich
patent: 5055746 (1991-10-01), Hu et al.
patent: 5068576 (1991-11-01), Hu et al.
patent: 5091677 (1992-02-01), Bleich et al.
patent: 5107184 (1992-04-01), Hu et al.
patent: 5629588 (1997-05-01), Oda et al.
patent: 5675221 (1997-10-01), Yoo et al.
patent: 5739643 (1998-04-01), Usui
patent: 5896015 (1999-04-01), Mader
Marshall O'Toole Gerstein Murray & Borun
Vo Tuyet T.
Wong Don
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