GB2201849A - Flicker lamp system - Google Patents

Abstract

To produce a flickering light effect, a power source 500, 601, 602 alternately yields positive and negative voltages, a first plurality of parallel - connected lamp assemblies 700 respond only to the positive voltage, and a second plurality of parallel - connected lamp assemblies 800 respond only to the negative voltage. Each assembly 700 or 800 has a lamp in series with a respective diode. The diode may be in the form of a disc-shaped assembly reversibly located in a lamp holder (Figs. 2, 3). Further parallel - connected lamp assemblies 900 without diodes are also provided. The power source may comprise anti-parallel thyristors 601, 602 alternately triggered by an oscillator 500 operating at a frequency below 3Hz. The system may be used for advertising displays and decoration. <IMAGE>

Description

FLICKER LAMP SYSTEM This invention relates to a flicker lamp system.

It is known to provide lamp systems in advertising boards and for decorative and other purposes wherein the lamps are caused to flicker.

In conventional systems, the lamps are connected in parallel and energised using an a.c. power source. A power distributor is necessary to implement the flickering effect for selected groups of parallel-connected lamps. The cost and complexity of such a system is high resulting in difficulties in manufacture. It is also known to incorporate a bimetallic switch in the lamps (such as those known by the reference C-7, C-9) which causes the lamps to flicker as the bimetallic switch opens and closes. In this case however, the intended flickering effect is unsatisfactory because the bimetallic switch can fail to open and close fully. Also, the type of flickering offered by the system is restricted to that inherent in the lamp.

The applicants have found that it is possible to provide a flickering lamp system which is capable of operating various types of flickering and which does not suffer from the disadvantages of conventional systems outlined above.

According to one aspect of this invention, there is provided a flicker lamp system including a power source operable alternately to produce positive and negative voltages, a first plurality of lamp assemblies connected in parallel to said source and responsive only to positive voltages, and a second plurality of lamp assemblies connected in parallel to said source and responsive only to negative voltages.

The invention will now be described by way of example, reference being made to the accompanying drawings, in which: Figure 1 is a circuit diagram illustrating a positively polarised lamp, a negatively polarised lamp and a non-polarised lamp connected in parallel; Figure 2 is a section view through a lamp assembly of an arrangement in accordance with an embodiment of this invention; Figure 3 is a section view through a diode assembly of the assembly of Figure 2; Figure 4 is a block diagram representing a flicker lamp system in accordance with an embodiment of this invention, and Figure 5 is an electrical circuit diagram of the system of Figure 4.

Referring to Figure 1 a sinusoidal or part-sinusoidal voltage from the power source is applied across the lamp assemblies 700, 800 and 900 in parallel. The assemblies 700 and 800 each contain a diode 701, 801 connected inversely. The diode 701 allows only positive half cycles to be applied across the lamp 702. The inversely connected diode 801 allows only negative half cycles to be applied across the lamp 802. The assembly 900 has no diode associated with it so that the whole of the voltage waveform is applied across the lamp 902. For convenience, the lamp assemblies are defined as follows: the lamp assembly 700 is of positive polarity, and the lamp assembly 800 is of negative polarity and the lamp assembly 900 is a non-polarity assembly.

In the system described below the C-7/C-9 decoration is taken as an example.

Referring to Figure 2, the structure of a lamp assembly will now be described. The-assembly includes a lamp housing 100 including a neutral contact 101 and a line voltage contact 102. The housing is threaded to receive a lamp 200 of the Edison screw cap type. A diode assembly 300 is shown interposed between the centre contact of the lamp 200 and the line voltage contact. The lamp may also make appropriate con'act without the diode assembly.

Referring now to Figure 3, the diode assembly comprises a hollow disc-shaped fire-resistant plastic plate 300c, a diode 400 located within the disc and two conductor plates 300a and 300b welded to the anode and the cathode at beads 300d and 300e.

Referring again to Figure 2, if the anode of the diode in the assembly 300 is connected to the line contact 102, the lamp assembly is a positive polarity lamp assembly 700. If the cathode of the diode is connected to the line contact, the lamp assembly is a negative polarity lamp assembly 800. If the diode is omitted, the lamp assembly will be a non-polarity assembly 900.

Referring now to Figure 4, the voltage waveform applied across the parallel connected lamps is controlled by means of two silicon controlled rectifiers (SCR) 601, 602 energised alternately by means of an astable oscillator trigger circuit 500. In the diagram the system is shown as including lamp assemblies 700, 800 and 900 of positive polarity, negative polarity and non-polarity respectively. It will be understood that the system includes several of each type of lamp assembly.

When the power supply is connected, the output signals at A and B are astable so that at any one time only one of the two SCRs 601, 602 will be working. Thus the common output point M of the SCRs 601, 602 will be at either a positive or a negative voltage.

The positive-polarity lamps 700 are activated only when point M is at a positive voltage, while the negative-polarity lamps 800 are activated only when point M is at a negative voltage. Therefore, the positive polarity lamp 700 or negative polarity lamps 800 flicker dependent on which SCR is activated, and the non-polarity lamps 900 remain on throughout the voltage variation.

Reference is now made to Figure 5 which illustrates the electrical circuit for the flicker lamp system. When the power source is connected, the astable oscillator-trigger circuit 500 starts to work immediately. The voltages at points A and B will be described. When point A is at a high voltage and point B is at a low voltage, the SCR 601 is turned on by the high voltage at point A which is applied to the gate terminal of the SCR 601. Therefore, the SCR 602 is turned off by applying a low voltage at point B to the gate terminal of SCR 602. Therefore, a positive voltage is produced at point M and the positive polarity lamps 700 will light up, but the negative polarity lamps 800 will be unlit. The non polarity lamps 900 will light up irrespective of the voltage at point M.

When point A is at a low voltage and piont B is at a high voltage the SCR 601 is turned off due to the low voltage from point A applied to the gate terminal of the SCR 601. Therefore the SCR 602 is turned on due to the high voltage from point B applied to the gate terminal of the SCR 602. Therefore, a negative voltage is produced at point M and the positive polarity lamps 700 be unlit but the negative polarity lamps 800 will light up. The non-polarity lamps 900 will light up as before.

With the two SCRs 600, 601 in the inverse-parallel connection as shown in Figure 5, their triggering potentials are each different with regard to the common ground in the circuit of Figure 5.

The trigger signal at point C is transferred to the gate of SCR 602 by means of a photo-isolator and the triggering function of trigger circuit 501. The oscillatory frequency of circuit 500 is designed to be below 3HZ, so that the flicker effect and its variations commanded by operation of the SCRs 600, 601 is visible to the human eye. The illustrated system has the following advantages: There is a reduction in cost compared to conventional flickering displays because conventional advertising lighting needs a large amount of electric wires, while this system needs only two conductive wires.

This system is designed to be manipulated to allow variations in configuration of the flickering lights. The user can arbitrarily arrange different polarity combinations of the incandescent lamps to give different flickering permutations merely by reversing or removing the diode assemblies.

The polarity lamps use half wave rectified direct current and thus the electric energy consumption is lower than that of a conventional system using alternating current. Mass production of this system is possible because the lamp assemblies require only the diode assembly of Figures in connection with ordinary incandescent lamps (see Figure 2). It is easy to assemble the diode assemblies pad and the lamps in production.

The described flicker control device possesses a neutral point which is grounded with the a.c. main. The system is thus consistent with electrical engirieering safety requirements.

The system described employs lamp assemblies of positive, negative and non-polarity. The system utilises the property of diodes to distinguish positive and negative voltages. Commercially available lamps are connected together in parallel into lamp strings with the polarities of the lamp assemblies being selected in accordance with the particular visual display. The lamp strings are supplied with power from a flicker control device which is supplied with a.c. power and outputs a rectified d.c. current with alternate series of positive and negative pulses. The system is suitable for advertising displays, decoration and other applications where a flickering effect is required.

The system is believed to be unique and is of high commercial value.

Claims (10)

1. A flicker lamp system including a power source operable alternately to produce positive and negative voltages, a first plurality of lamp assemblies connected in parallel to said source and responsive only to positive voltages, and a second plurality of lamp assemblies connected in parallel to said source and responsive only to negative voltages.

2. A flicker lamp system according to claim 1, wherein each of the lamp assemblies of said first plurality includes a forward biassed diode in series with a lamp and each of the lamp assemblies of said second plurality includes a reverse biassed diode in series with a lamp.

3. A flicker lamp system according to claim 2 wherein said lamp assemblies further include a lamp-holder adapted releasably to hold a lamp and having electrical contacts for engaging corresponding contacts on said lamp, and said diode is contained in a diode assembly interposable between and in electric contact with one of the contacts on the lamp and corresponding contact on the holder.

4. A flicker lamp system according to claim 1 wherein said diode assembly is reversibly interposable between the contacts of the lamp and the lamp holder, thereby to allow selection of the polarity to which said lamp is responsive.

5. A flicker lamp system according to any one of the preceding claims wherein said power source is operable to supply a positive rectified voltage alternately with a negative rectified voltage.

6. A flicker lamp system according to claim 5, wherein said power source includes two silicon controlled rectifiers arranged inversely in parallel and oscillator means for alternately activating said silicon controlled rectifiers.

7. A flicker lamp system according to claim 6 wherein said oscillator means comprises an astable multivibrator.

8. A flicker lamp assembly according to claim 3 wherein said lamp and said holder are of the Edison screw type and said diode assembly comprises generally flat cylindrical housing containing a diode and including on its end faces contacts for supplying current to and from said diode.

9. A flicker lamp assembly substantially as hereinbefore described with reference to and as illustrated in, any of the accompanying drawings.

10. Any and all novel features and combinations thereof disclosed herein.