GB2175465A - Light emitting diode operating circuit - Google Patents

Light emitting diode operating circuit Download PDF

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Publication number
GB2175465A
GB2175465A GB08611525A GB8611525A GB2175465A GB 2175465 A GB2175465 A GB 2175465A GB 08611525 A GB08611525 A GB 08611525A GB 8611525 A GB8611525 A GB 8611525A GB 2175465 A GB2175465 A GB 2175465A
Authority
GB
United Kingdom
Prior art keywords
diode means
leds
switch means
indicator assembly
diode
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.)
Withdrawn
Application number
GB08611525A
Other versions
GB8611525D0 (en
Inventor
Alan Dewhurst
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
DEWHURST PLC
Original Assignee
DEWHURST PLC
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by DEWHURST PLC filed Critical DEWHURST PLC
Publication of GB8611525D0 publication Critical patent/GB8611525D0/en
Publication of GB2175465A publication Critical patent/GB2175465A/en
Withdrawn legal-status Critical Current

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Classifications

    • 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
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/50—Circuit arrangements for operating light-emitting diodes [LED] responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits
    • H05B45/59—Circuit arrangements for operating light-emitting diodes [LED] responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits for reducing or suppressing flicker or glow effects

Abstract

A lift indicator assembly comprises light emitting diode means 10, and switch means 15, which may comprise a relay or a transistor, thyristor or other semi-conductor device, for disabling said diode means 10. Said switch means 15 are arranged to short-circuit said diode means 10 and alternatively or additionally to disconnect said diode means from a voltage supply near said diode means, when said diode means is in an "off" condition. The arrangement prevents operation of the diode means 10 by spurious voltages. <IMAGE>

Description

SPECIFICATION Improvements in or relating to the operation and control of light emitting diodes This invention relates to the operation and control of light-emitting diodes (LEDS).
In some applications of LEDs, for example in lift indicator systems, small spurious ambient voltages may be picked up which cause the LEDs to flicker indiscriminately. This can occur in LEDs installed in a lift car floor indicator due to spurious voltages in the shaft wiring.
The present invention has for its object the prevention of this undesirable phenomenon.
According to the present invention there is provided a lift indicator assembly comprising light emitting diode means, switch means for disabling said diode means, said switch means being arranged to short-circuit said diode means when said diode means is in an "off" condition. Alternatively or additionally, said switch means is arranged to disconnect said diode means from a voltage supply near said diode means, when said diode means is in an "off" condition.
In order that the invention may be well understood, an embodiment thereof will now be described, by way of example only, reference being made to the accompanying drawings in which: Figure 1 shows a circuit diagram according to the embodiment and Figures 2A to C show rear, side and plan views respectively of part of a lift indicator assembly according to the embodiment.
Referring to Fig. 1, a series array of four LEDs 10 incorporating a resistor 11 is energised from the D.C. output terminals 12 of a bridge rectifier 13 having A.C. input terminals 14. In the embodiment shown, a relay 15 has its armature winding 16 connected across the D.C. terminals 12 and has a contact arm 17 movable between contacts 18a and 18b. The relay is shown in the non-energised position in which no A.C. voltage is present at the terminals 14 and it is intended that the LEDs should not illuminate. In this condition, the LED array is disconnected from the rectifier terminals 12 and short-circuited through the relay contact 1 8a so that spurious voltage cannot illuminate the LEDs.When an A.C. voltage is applied to the rectifier with the intension of illuminating the LEDs, relay 15 is energised and contact arm 17 moved into contact with contact 18b, opening the short-circuit and connecting D.C. voltage to the LEDs.
In the circuit of Fig. 1, the relay 15 when deenergised both disconnects the LEDs from the voltage supply and also places a shortcircuit across the LEDs.
However, alternative switch means, such as a transistor, thyristor or other semiconductor device may be used, and also in some situations it may be sufficient to use switch means such as a make-or break relay which only disconnects the LEDs from the supply or, alternatively, only places a short-circuit across the LEDs.
The invention may be embodied in miniaturised form so as to be particularly suitable for incorporation in push-buttons or indicators for illuminating the same.
Our range of vandal resistant controls "Series US 81" described in our brochure "Publication No. SF 600-85 Issue 179", includes a push-button "Ref. SUS 81 AA" illuminated by an incandescant bulb mounted in a removable moulded carrier inserted in the rear of the push-button. Figs. 2A to C of the accompanying drawings show views of a modified carrier 20 incorporating the embodiment in which components shown in the circuit of Fig. 1 are indicated by the same references.
As seen in Fig. 2A, the various components are inter-connected by, and mounted on, a rectangular printed circuit board. The four LEDs 10 provide illumination in place of an incandescant bulb and the carrier assembly is designed to be a clip-in replacement for the standard incandescant bulb carrier assembly.
1. A lift indicator assembly comprising light emitting diode means, switch means for disabling said diode means said switch means being arranged to short-circuit said diode means when said diode means is in an "off" condition.
2. A lift indicator assembly comprising light emitting diode means, and switch means for disabling said diode means, said switch means being arranged to disconnect said diode means from a voltage supply near said diode means, when said diode means is in an "off" condition.
3. A lift indicator assembly as claimed in claim 2, wherein said switch means is further arranged to short circuit said diode means when said diode means is in said "off" condition.
4. A lift indicator assembly as claimed in any preceding claim, wherein said switch means comprises a relay.
5. A lift indicator assembly as claimed in any one of claims 1 to 3, wherein said switch means comprises a transistor, thyristor or similar semiconductor switching device.
6. A lift indicator assembly as claimed in any preceding claim, wherein said diode means consists in four light emitting diodes and a resistor is connected in series with said diode means across a D.C. supply.
7. A lift indicator assembly as claimed in claim 6 wherein said four light emitting diodes are mounted one at each corner of a rectangular printed circuit board having said switch means also mounted thereon.
8. A lift indicator assembly as claimed in claim 7 further comprising a bridge rectifier
**WARNING** end of DESC field may overlap start of CLMS **.

Claims (9)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Improvements in or relating to the operation and control of light emitting diodes This invention relates to the operation and control of light-emitting diodes (LEDS). In some applications of LEDs, for example in lift indicator systems, small spurious ambient voltages may be picked up which cause the LEDs to flicker indiscriminately. This can occur in LEDs installed in a lift car floor indicator due to spurious voltages in the shaft wiring. The present invention has for its object the prevention of this undesirable phenomenon. According to the present invention there is provided a lift indicator assembly comprising light emitting diode means, switch means for disabling said diode means, said switch means being arranged to short-circuit said diode means when said diode means is in an "off" condition. Alternatively or additionally, said switch means is arranged to disconnect said diode means from a voltage supply near said diode means, when said diode means is in an "off" condition. In order that the invention may be well understood, an embodiment thereof will now be described, by way of example only, reference being made to the accompanying drawings in which: Figure 1 shows a circuit diagram according to the embodiment and Figures 2A to C show rear, side and plan views respectively of part of a lift indicator assembly according to the embodiment. Referring to Fig. 1, a series array of four LEDs 10 incorporating a resistor 11 is energised from the D.C. output terminals 12 of a bridge rectifier 13 having A.C. input terminals 14. In the embodiment shown, a relay 15 has its armature winding 16 connected across the D.C. terminals 12 and has a contact arm 17 movable between contacts 18a and 18b. The relay is shown in the non-energised position in which no A.C. voltage is present at the terminals 14 and it is intended that the LEDs should not illuminate. In this condition, the LED array is disconnected from the rectifier terminals 12 and short-circuited through the relay contact 1 8a so that spurious voltage cannot illuminate the LEDs.When an A.C. voltage is applied to the rectifier with the intension of illuminating the LEDs, relay 15 is energised and contact arm 17 moved into contact with contact 18b, opening the short-circuit and connecting D.C. voltage to the LEDs. In the circuit of Fig. 1, the relay 15 when deenergised both disconnects the LEDs from the voltage supply and also places a shortcircuit across the LEDs. However, alternative switch means, such as a transistor, thyristor or other semiconductor device may be used, and also in some situations it may be sufficient to use switch means such as a make-or break relay which only disconnects the LEDs from the supply or, alternatively, only places a short-circuit across the LEDs. The invention may be embodied in miniaturised form so as to be particularly suitable for incorporation in push-buttons or indicators for illuminating the same. Our range of vandal resistant controls "Series US 81" described in our brochure "Publication No. SF 600-85 Issue 179", includes a push-button "Ref. SUS 81 AA" illuminated by an incandescant bulb mounted in a removable moulded carrier inserted in the rear of the push-button. Figs. 2A to C of the accompanying drawings show views of a modified carrier 20 incorporating the embodiment in which components shown in the circuit of Fig. 1 are indicated by the same references. As seen in Fig. 2A, the various components are inter-connected by, and mounted on, a rectangular printed circuit board. The four LEDs 10 provide illumination in place of an incandescant bulb and the carrier assembly is designed to be a clip-in replacement for the standard incandescant bulb carrier assembly. CLAIMS
1. A lift indicator assembly comprising light emitting diode means, switch means for disabling said diode means said switch means being arranged to short-circuit said diode means when said diode means is in an "off" condition.
2. A lift indicator assembly comprising light emitting diode means, and switch means for disabling said diode means, said switch means being arranged to disconnect said diode means from a voltage supply near said diode means, when said diode means is in an "off" condition.
3. A lift indicator assembly as claimed in claim 2, wherein said switch means is further arranged to short circuit said diode means when said diode means is in said "off" condition.
4. A lift indicator assembly as claimed in any preceding claim, wherein said switch means comprises a relay.
5. A lift indicator assembly as claimed in any one of claims 1 to 3, wherein said switch means comprises a transistor, thyristor or similar semiconductor switching device.
6. A lift indicator assembly as claimed in any preceding claim, wherein said diode means consists in four light emitting diodes and a resistor is connected in series with said diode means across a D.C. supply.
7. A lift indicator assembly as claimed in claim 6 wherein said four light emitting diodes are mounted one at each corner of a rectangular printed circuit board having said switch means also mounted thereon.
8. A lift indicator assembly as claimed in claim 7 further comprising a bridge rectifier mounted on said circuit board for supplying said diodes and said switch means.
9. A lift indicator assembly substantially as herein described with reference to the accom paning drawings.
GB08611525A 1985-05-16 1986-05-12 Light emitting diode operating circuit Withdrawn GB2175465A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB858512424A GB8512424D0 (en) 1985-05-16 1985-05-16 Operation & control of light emitting diodes

Publications (2)

Publication Number Publication Date
GB8611525D0 GB8611525D0 (en) 1986-06-18
GB2175465A true GB2175465A (en) 1986-11-26

Family

ID=10579241

Family Applications (2)

Application Number Title Priority Date Filing Date
GB858512424A Pending GB8512424D0 (en) 1985-05-16 1985-05-16 Operation & control of light emitting diodes
GB08611525A Withdrawn GB2175465A (en) 1985-05-16 1986-05-12 Light emitting diode operating circuit

Family Applications Before (1)

Application Number Title Priority Date Filing Date
GB858512424A Pending GB8512424D0 (en) 1985-05-16 1985-05-16 Operation & control of light emitting diodes

Country Status (1)

Country Link
GB (2) GB8512424D0 (en)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2218283A (en) * 1988-04-13 1989-11-08 Square D Co Pilot light assembly
EP0762651A2 (en) * 1995-09-07 1997-03-12 Siemens Aktiengesellschaft Driver circuit for a light emitting diode
WO1999038361A1 (en) * 1998-01-21 1999-07-29 Siemens Aktiengesellschaft Circuit for operating an led luminous signal
DE102009050203A1 (en) * 2009-10-21 2011-04-28 Osram Gesellschaft mit beschränkter Haftung Lighting device/component e.g. LED retrofit lamp, has spirit light suppression circuit activated or deactivated by switch, where suppression circuit includes counter-phase compensation line, shield and capacitor
DE102014101421B3 (en) * 2014-02-05 2015-07-02 Gira Giersiepen Gmbh & Co. Kg Electrical circuit for the building system technology to avoid caused by capacitive coupling currents

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3801866A (en) * 1972-12-11 1974-04-02 P Schmidgall Flashing novelty device
GB1460228A (en) * 1973-12-22 1976-12-31 Itt Light emitting diode connected to a coil
GB1543722A (en) * 1976-06-11 1979-04-04 Ferranti Ltd Display device energisation circuits
EP0115896A1 (en) * 1983-02-07 1984-08-15 Koninklijke Philips Electronics N.V. Optical indicator device

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3801866A (en) * 1972-12-11 1974-04-02 P Schmidgall Flashing novelty device
GB1460228A (en) * 1973-12-22 1976-12-31 Itt Light emitting diode connected to a coil
GB1543722A (en) * 1976-06-11 1979-04-04 Ferranti Ltd Display device energisation circuits
EP0115896A1 (en) * 1983-02-07 1984-08-15 Koninklijke Philips Electronics N.V. Optical indicator device

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2218283A (en) * 1988-04-13 1989-11-08 Square D Co Pilot light assembly
GB2218283B (en) * 1988-04-13 1992-09-30 Square D Co Pilot light assembly
EP0762651A2 (en) * 1995-09-07 1997-03-12 Siemens Aktiengesellschaft Driver circuit for a light emitting diode
EP0762651A3 (en) * 1995-09-07 1999-02-03 Siemens Aktiengesellschaft Driver circuit for a light emitting diode
WO1999038361A1 (en) * 1998-01-21 1999-07-29 Siemens Aktiengesellschaft Circuit for operating an led luminous signal
DE102009050203A1 (en) * 2009-10-21 2011-04-28 Osram Gesellschaft mit beschränkter Haftung Lighting device/component e.g. LED retrofit lamp, has spirit light suppression circuit activated or deactivated by switch, where suppression circuit includes counter-phase compensation line, shield and capacitor
DE102009050203B4 (en) * 2009-10-21 2012-05-03 Osram Ag Device with a suppression circuit of a residual light
DE102014101421B3 (en) * 2014-02-05 2015-07-02 Gira Giersiepen Gmbh & Co. Kg Electrical circuit for the building system technology to avoid caused by capacitive coupling currents

Also Published As

Publication number Publication date
GB8512424D0 (en) 1985-06-19
GB8611525D0 (en) 1986-06-18

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WAP Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1)