Light Sources for Signal Systems

Presentation for the lecture

incoherent light sources

Steinfurt, 23. Juni 2008

Tobias Scholz

Applications for Signal Systems

Signal System

- Lighthouse

- Traffic Light

Outline

Outline

- Traffic Light

Summary

Tobias Scholz

In which areas are signal lights necessary?

Applications for Signal Systems

Tobias Scholz

Signal System - Lighthouse

Signal System - Lighthouse

Tobias Scholz

Most important lighthouse in ancient times: The Pharos of Alexandria

299 – 279 B.C.: built by the order of Ptolemaios I

Highest Lighthouse ever built (115 – 160 m)

Signal System - Lighthouse

Visibility range about 40 km

Tobias Scholz

One of the first Lighthouses in Western Europe: Tower of Hercules

A Coruna, Spain

Built in 110 AD

Initial height : 36 m (today 68 m)

Signal System - Lighthouse

The tower is the oldest building in use

Tobias Scholz

One of the first Lighthouses in Germany: Travemünde

First mentioned in 1226

A new tower was built in 1539

Height: 31 m

The lighthouse operated from 1539

until 1972

Signal System - Lighthouse

until 1972

Tobias Scholz

History of Light Sources for Lighthouses

- In ancient times, Middle Ages until 1800: fire was used as light source

- 1782: the physicist Aimé Argand invented the Argand burner. It consists

of a cylindrical wick housed between two concentric metal tubes

- At 1800: These Light sources were used in Lighthouses

- 1820 :Fresnel designed an optical lense by division of a conventional

spherical lense into independent segments

Signal System - Lighthouse

spherical lense into independent segments

the radiation propagates parallel

- Today, Halide bulps or discharge lamps are mostly used

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- Beacon

- Direction Light

- Range Lights

- Warning Light

Tasks of Lighhouses

Signal System - Lighthouse

Lighthouse in Beachy Head [UK]

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- Beacon

- Direction Light

- Range Lights

- Warning Light

Tasks of Lighhouses

Signal System - Lighthouse

Tobias Scholz

- Beacon

- Direction Light

- Range Lights

- Warning Light

Tasks of Lighhouses

Signal System - Lighthouse

Tobias Scholz

Tasks of Lighhouses

- Beacon

- Direction Light

- Range Lights

- Warning Light

Signal System - Lighthouse

Tobias Scholz

Preconditions for light sources of Lighthouses

- High Luminous Intensity

- No special Lamp

- High life cycle

a) Metal halide lamp

Signal System - Lighthouse

d

a) Metal halide lamp

230 V / 400 W

b) Metal halide lamp (pearl)

230 V / 400 W

c) Metal halide lamp

400 V / 2000 W

d) Incandescent light bulb

220 V / 2000 W

Tobias Scholz

Metal halide lamp 230 V / 400 W

Time dependent presentation of luminous intensity on the horizon

for each light source

Incandescent light bulb 220 V / 2000 W

Signal System - Lighthouse

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Metal halide lamp (pearl) 230 V / 400 WMetal halide lamp 400 V / 2000 W

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Tobias Scholz

Construction of Lighting Systems in Lighthouses

Signal System - Lighthouse

Tobias Scholz

Construction of Lighting Systems in Lighthouses

Signal System - Lighthouse

Tobias Scholz

Function of Fresnel lenses

Construction of Lighting Systems in Lighthouses

Signal System - Lighthouse

Tobias Scholz

Function of Fresnel lenses

Construction of Lighting Systems in Lighthouses

Signal System - Lighthouse

Tobias Scholz

Signal System – Traffic Lights

Signal System – Traffic lights

Tobias Scholz

On December 10th, 1868, the first traffic light has been installed

in London at the crossroad of George and Bridge Street near

the "Houses of Parliament". This traffic light was invented by J.

P. Knight.

Signal System – Traffic Lights

Tobias Scholz

1910: Earnest Sirrine from Chicago patented the first

electronical operated traffic light

1912: The first electric traffic signal using red and

green lamps was installed in Salt Lake City, US.

Signal System – Traffic Lights

Tobias Scholz

1914: The traffic lights installed in Cleveland,Ohio on

August 5th, is said to be the world's first official traffic

light

1917: The first automatic traffic signal got a patent

in the US. In the same year the first traffic tower

Signal System – Traffic Lights

in the US. In the same year the first traffic tower

was situated at a crossroad to regulate traffic due

to increased traffics

Tobias Scholz

1920:The first tri-colored traffic lights

with red, yellow and green lanterns were

put to service in NYC and Detroit

Signal System – Traffic Lights

Tobias Scholz

1922: Europe's first traffic lights were

established in Paris and Hamburg.

Signal System – Traffic Lights

1924: A traffic tower was installed in

Berlin at the Potsdamer Square on

October 21st

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1933: In Europe the first pedestrian light

was established in Copenhagen

(followed by one in Berlin in 1937)

Signal System – Traffic Lights

1952: On Feb. 5th, the first automatic

pedestrian lights displaying "Walk" /

"Don't Walk" were established in NYC

Tobias Scholz

1961: Karl Peglau, Chief Psychologist of GDR's Traffic

Authority, presented in Eastern Berlin his plans on the

regulation of pedestrian traffic by means of man

schemed signalmasks

Signal System – Traffic Lights

Tobias Scholz

Preconditions for light sources of traffic lights

- luminance: 2·103 - 8·103 cd/m² (recommendation of the

Strahlenschutzkommission in 2006)

- No special Lamp

- High life cycle

Signal System – Traffic Lights

Incandescent light bulb10V / 20W

Incandescent light bulb 230V / 60W

halogen bulb 10V / 20W

Tobias Scholz

Application of LED‘s in traffic lights

Advantage: - higher energy efficieny

- higher life cycle

- almost no phantom signal

- higher luminance

- uniform illumination

Signal System – Traffic Lights

- uniform illumination

Two concepts:

- LED-Cluster

- central light source

Tobias Scholz

LED-Cluster:

Application of LED‘s in traffic lights

Signal System – Traffic Lights

Tobias Scholz

LED-Cluster:

lenses are positioned in front of LEDs

uniform illumination

Application of LED‘s in traffic lights

Signal System – Traffic Lights

Red light: LED-Cluster

Yellow Light: Incandescent light bulb

10V / 20W

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LED-Blank

Aluminium sheet

Central light source:

Application of LED‘s in Traffic Lights

Signal System – Traffic Lights

condenserdivergent lens

driver unit

aperture

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Under direct solar radiation: it appears that the traffic

light gives a signal although it is off

Different types of phantom signals:

- reflexion on front surfaces of the optics

Phantom Signal

Signal System – Traffic Lights

Tobias Scholz

Under direct solar radiation: it appears that the traffic

light gives a signal although it is off

Different types of phantom signals:

- reflexion on front surfaces of the optics

- reflexion inside the lamp

Phantom Signal

Signal System – Traffic Lights

- reflexion inside the lamp

Tobias Scholz

Measures against phantom signals

Phantom Signal

Signal System – Traffic Lights

Tobias Scholz

Phantom Signal

Measures against phantom signals

Signal System – Traffic Lights

Tobias Scholz

Phantom Signal

Measures against phantom signals

Signal System – Traffic Lights

Tobias Scholz

LED-Cluster

Phantom Signal

Measures against phantom signals

Signal System – Traffic Lights

Central light source:

LED-Blank

condenserdivergent lens

driver unit

aperture

Sheet of aluSheet of alu

LED-Blank

driver unit

aperture

condenser divergent lens

Tobias Scholz

Applications: - Lighthouse

- Traffic lights

Light sources: - High luminous intensity

- luminance: 2·103 - 8·103 cd/m²

- High life cycle

- No special lamp

Problems: - Phantom signal

Summary

Problems: - Phantom signal

Tobias Scholz

Thank you for your attention!