NO337214B1 - Two-position sign - Google Patents

Description

Field of the invention

The present invention relates to variable signs in general, and more specifically to a variable traffic sign.

Background

Along our roads today there is a veritable flora of traffic signs. Most have a permanent, i.e. fixed and unchanging message, but there is also a need for signs that can be varied, either by varying the information content, such as in light boards, or by the sign being "turned on and off", so-called two- position sign.

Two-position signs are typically used for temporary changes in the traffic pattern or driving pattern, to warn of work on the road, detours, danger of traffic jams, moose, wind, slippery road surfaces etc. or changes to speed limits, e.g. a reduced speed limit at a school during school hours.

Two-position signs are most often realized as LED signs, where LED lamps form points that outline the outline of arrows, numbers or characters. Such signs have both advantages and disadvantages. The disadvantages consist in the fact that the signs visually differ greatly from ordinary stationary signs, and they do not satisfy the sign standards (are inverse, i.e. the number/text lights up in contrast to stationary signs, where the number/text is black). Furthermore, LED signs are not reflective and they need a constant power source, which results in high energy consumption. Some LED bulbs will eventually fail and cause dead spots in the sign. Since "wear and tear" occurs on the LED bulbs so that the light yield decreases over time, this has the effect that when bulbs expire and have to be replaced, the new bulbs will shine with greater intensity than the old bulbs. If it is desired to make changes to the sign, for example changes to numbers or text, this is usually very difficult and the sign usually has to be replaced.

Mechanically variable traffic signs are also in use. Such signs are often made up of triangular, horizontal slats. Each lamella contains a strip of the sign surface. The slats have different information on each side, and can be turned so that three different messages can be displayed, or two messages and "off". The disadvantages here are that the mechanism is exposed to mechanical wear and cannot withstand standing outside in the Norwegian climate, especially cold. Such signs are relatively expensive and include heavy and space-consuming mechanics.

Two-position signs with a case with a transparent front plate have also been presented. A normal reflective sign is mounted on the back wall inside the sign box. The front plate comprises a transparent glass or plastic plate glued to an LCD foil or "LCD curtain" which can be made to either let light through, so that the sign is visible from the outside, or become gray and thereby flicker, allowing light to pass through so that the sign is no longer visible. A disadvantage of such a construction is that it is difficult to get the LCD curtain tight enough. It has easily become such that strong colors on the sign can be seen even when the curtain is closed. To remedy this, the distance between the LCD curtain and the sign must be increased, but this results in a deep and large sign box. Another disadvantage is that the front glass is exposed to wear due to traffic noise<y>, flushing, snow from plows, etc., and therefore must be replaced once in a while. When the LCD foil is attached to the faceplate, this is an expensive component to replace.

From US 4 893 903 a sign box with a two-position sign and LCD shutter is known.

GB 1 457 531 shows one or more LCD panels acting as shutters.

FR 2 695 504 shows a sign box with a two-position sign with a transparent front.

US 5,412,492 shows a traffic light with a liquid crystal (PDLC) lens which may be transparent or non-transparent.

Summary of the Invention

The purpose of the present invention is to provide a two-position sign which overcomes the aforementioned problems with known signs of this type.

This is achieved with a sign according to the invention as it appears from the subsequent patent claims.

The invention comprises a two-position sign with a sign box with a transparent front plate, a back wall, and a reflective sign mounted on the back wall inside the sign box. The sign is characterized by the fact that an "LCD curtain" is fitted inside the sign box behind the front plate, as the LCD curtain comprises a transparent plate which is coated with an LCD foil on the front surface and an LCD foil on the rear surface, in that both LCD foils with power supply can simultaneously be made to be transparent and thereby be completely transparent, or without power supply not to be transparent and thereby be opaque. The use of two foils means that the fixed sign on the back wall cannot be seen when the LCD curtain is "switched off", and without

that the sign box must be made unnecessarily large and deep.

According to one embodiment of the sign, the transparent plate with the affixed foils is at least 15 mm thick to ensure that light that escapes/"leaks" through the front LCD foil when it is not transparent, is stopped by the rear LCD foil. By making the transparent plate sufficiently thick, i.e. so that there is a greater distance between the LCD foils, the LCD curtain will seal better when closed, and the sign box can be made shallower.

Such a sign box can be a total of 10 - 15 cm deep. This is a big reduction compared to sign boxes that use a curtain with just one LCD foil.

The two-position sign can also include one or two light sources inside the sign box. This achieves two effects, firstly, the visibility of the sign on the back wall is increased when the daylight fades, and secondly, shadows on the sign are avoided in strong sunlight.

The two-position sign can also include a heating foil glued to the inside of the front plate. This is to avoid dew and frost on the front plate. Some moisture will always penetrate such a sign, and one way to prevent moisture problems is to use some form of heat source inside the box.

The sign can also include a foil glued to the outside of the front plate, which helps dirt run off when it rains. Especially in winter, signs along the country road are prone to being splashed down and therefore need to be cleaned from time to time. There are now special foils on the market with a self-cleaning effect.

The sign can further comprise a control unit arranged to receive control signals via a wired Ethernet or wireless communication connection, the control unit being connected to the LCD foils and turning them on or off. This ensures that all signs along the road can be controlled from a remote control centre.

The communication connection can be a Bluetooth, WiFi, mobile phone or mobile radio connection. The communication connection must be adapted to the local possibilities regarding coverage etc.

The two-position sign can further comprise a GPS receiver which is connected to the control unit. The purpose of this is that the sign can report to a control center with a real position. This is particularly relevant with movable signs, which are, for example, set up temporarily in connection with work on the road or the like.

The two-position sign can also include a weather station designed to measure temperature, humidity, wind speed and amount of precipitation, the weather station being connected to the control unit. The information from the weather station can be transferred to a control center and can then be used to notify motorists of difficult driving conditions, the need for plowing, etc.

Brief description of the drawings

The invention will now be described in detail with reference to the attached drawings, where

Fig. 1 shows the sign arrangement in section,

Fig. 2 shows the sign arrangement seen from the front, respectively. with the light curtain open a) and closed

b),

Fig. 3 is a schematic representation of the sign's control electronics.

Detailed description

As Fig. 1 shows, the invention includes a sign box 1 with a back wall 2 and side walls 3. The front includes a transparent screen plate 4. Behind the screen plate 4 is mounted an LCD curtain in the form of a transparent plate 5 where on both sides a active LCD foil 6, 7. The LCD foils are electrically controlled, and by applying the right voltage across the LCD foils they can be made to either be completely transparent, or be opaque.

Such LCD foils are well-known technology today. The foil consists of soft plastic mixed with a crystal liquid and is called Polymer Dispersed Liquid Crystal Display (PDLC Display). An electrically conductive and transparent coating consisting of indium tin oxide is applied to each side of the plastic foil. The molecules in the crystal liquid are shaped like a pencil. When no current is connected to the indium tin oxide coating, the crystal molecules lie hollow to bolts, and the PDLC foil is grey-white. When current is connected to these coatings, all the molecules align perpendicular to the surface and the foil is completely transparent.

PDLC foils have several advantages that come in handy in the invention, but there are several LCD products available that may be relevant in this context.

An ordinary, permanent, reflective sign 8 is mounted on the back wall of the sign box 1.

With the help of the LCD curtain, the front plate of the light box can be made transparent or opaque, so that the sign 8 is either visible or not visible from the outside, Fig. 2. When the curtain is open, the sign will appear like any other normal reflective traffic sign. The fixed sign can easily be replaced with another standard fixed sign.

In order for this two-position sign to have the desired effect, i.e. that it effectively blocks the view of the sign when the curtain is closed, there are certain dimensions that must be observed. Firstly, there must be some distance between the LCD foils 6, 7 in the curtain. In the present case, the LCD foils are glued to each side of a Plexiglas plate that is at least 15 mm thick. If thinner plates are used, e.g. 6 mm, which is a common dimension in the trade, the LCD foils will not seal optimally. The transparent plate should therefore be 15 mm or more. Furthermore, there must be at least 6 cm distance between the LCD curtain and the sign on the back wall. With conventional solutions, i.e. with a single LCD foil in the curtain, the sign box must be made at least 25 cm deep so that the sign cannot be seen from the front when the curtain is closed. When using an LCD curtain with double LCD foils, and with sufficient distance between the foils, as mentioned above, the sign box can be made much shallower, down to 8 cm.

Both the sign 8 on the back wall and the LCD foils are scattering elements (when the LCD foils are "switched off"). The dimensioning mentioned above is due to the fact that the light must spread sufficiently before it reaches the next element.

The sign box 1 contains, apart from the sign on the back wall, one or two light sources 9, a heat source 19, a foil on the outside of the front plate that removes dirt when it rains (not shown), a control unit 11 and a power supply unit 12, Fig. 3. The sign box can also be equipped with a mask 10 on the front which is adapted to the size and shape of the fixed sign 8.

The heat source can be a thermostatically controlled heating cable, but preferably the heat source is realized as a heating foil 19 glued to the inside of the front wall, again controlled by a thermostat. The heat source ensures the function of the LCD foil, and prevents frost or dew from forming on the foil. To reduce heat loss, the sign box can be equipped with insulation in or on the walls.

The light source can consist of two LED rails, i.e. one mounted in the upper part of the sign box just behind the LCD curtain, and one mounted in the lower part of the sign box, also just behind the LCD curtain. The LED rails are arranged to light up when the LCD curtain is "open" and the fixed sign is visible. The light from the LED rails works to enhance the reflection from the fixed sign, and will reinforce the sign's message. Furthermore, the upper LED rail will provide sun shade in the upper part of the sign box. Without such lighting, one may experience, on days with strong sunlight, that the light from the sun in the sky is shaded by the edge of the sign box, so that a shadow is formed over the upper part of the fixed sign on the back wall.

The control unit 11 must be able to:

communication

positioning

inputs for detectors

outputs for controlling a relay for sign on/off

The control unit can be equipped with a power-saving function so that only necessary electronics are active.

Inputs from detectors can be:

Signs on or off

Status for opening signs

Measurement of temperature

Measurement of humidity

Measurement of wind

Measurement of car density

Measurement of speed

The detectors can consist of a "weather station" 13, as well as means 14 for detecting passing cars, such as an inductive loop or pressure hose laid over the road, alternatively an optical system. The weather station includes a temperature gauge, hygrometer, anemometer and precipitation gauge. The control unit 11 is designed to calculate traffic density and speed from the signals received from the aforementioned means. The control unit will be a Machine to Machine (M2M) unit (comparable to PLC or embedded PC) with peripheral units. The peripheral units include memory and communication interface, possibly also a local user interface (user unit) and/or a GPS receiver.

The communication interface can be an Ethernet port 17 and/or devices for wireless communication, such as a mobile phone device (GSM/GPRS or other communication standards) 16, a mobile radio device, WiFi connection 18 or devices for short-range communication (e.g. Bluetooth).

It is also possible to install local user devices, such as a screen and a keyboard, which can either be accessed via a hatch on the box, or are mounted inside the box so that it must be opened. As of today, however, a solution where the device is controlled from a mobile phone is preferred, among other things to prevent vandalism.

The control unit is set via the communication interfaces, or locally by direct entry on a user unit.

Local radio control (short-distance communication) is primarily used for work notification and for communication between signs in a sign system with "master" and "slaves". Range depends on the geographical conditions and must be tested in each individual case.

Local time management can, for example, be used to manage danger or prohibition signs in connection with schools.

Local dynamic control means that the variable sign's message changes automatically linked to various categories of sensors for traffic management, queue conditions, weather/driving conditions, air quality etc. or on the basis of changes in the status of safety devices in tunnels.

The signs can also be controlled individually by an operator from an operations center or as part of a pre-programmed implementation sequence for a pre-planned traffic regulation. In practice, individual signs may be subject to several categories of management. This means that the sign can receive control commands from several sources. In such cases, it will be required to link a priority management function to the sign.

A sign can be a dedicated (stand-alone) unit, or form part of a sign system with one or more groups of signs (for example, when warning about work or marking a detour route). If variable signs are used in a sign system, a main sign with several sub-signs can be used, for example. Main signs can be controlled directly, while sub-signs are controlled from the main sign.

When establishing or changing fixed settings in the management system, this must be able to be set up for dedicated signs or for one or more groups. All fixed settings must be able to be manually overridden by sign. When the settings have been transferred to the control system, the information must be saved, so that any power cuts do not affect the settings.

Examples of settings can be date and time, which are done at system startup. The clock function must have a battery back-up so that any power outages do not affect the clock setting.

In order to limit power consumption, the control unit can be arranged to disconnect the communication at given times. This must be programmable and the following situations must be covered:

How often the communication system should be made active

Fixed connection

Connected for a certain time

Connected at given time

Depending on the time of day

If the management system is updated with information about a new user, a message must be sent to the superior system (operation center) when a change is made. In the event of a communication breakdown, the existing setup in the control unit is used.

The control unit 11 is also connected to a GPS receiver 15 which provides the opportunity to continuously report the sign's current position to the operations centre.

Position is set by:

installation of signs

at the start of signs that are mobile (e.g. work notification)

upon request

Sign position will be used together with a map system at the operations center to quickly obtain information about the status of signs.

Basically, all controllable signs (except radio-controlled signs) require condition and error monitoring of the sign from a responsible operating centre. Any change to the sign's position, whether it is activated controlled by the operator, time-controlled or dynamically on the basis of control algorithms, must be logged. For regulatory signs, this is particularly important because of the necessary reliable documentation in any legal disputes as a result of, for example, traffic accidents or traffic offences. Central condition monitoring is also necessary as documentation that the sign has achieved the desired position. The condition monitoring must be based on feedback from the physical sign out in the field.

All variable signs must be fault monitored. Detected errors must be logged as a basis for error correction in accordance with established procedures for the individual sign. All status or error messages must be logged both in signs and in the overall control system. High security is required for the logs.

It is important that security is high as the communication to signs can be open communication channels such as mobile networks. Commands to signs must be transmitted without delay, and acknowledgment of received messages must always be transmitted. Encryption and passwords must be used when using communication. Anyone who tries to contact the higher-level system is logged together with the date and time.

All changes must be detected and saved with:

Date/time

Identification of the person/s who change or attempt to change

Type of message

In the event of a failure of the main power supply, a backup solution is selected and a notification is given to the superior system.

Power supply must be possible with:

brought forward ordinary power cable (220 VAC)

battery combined with street light or solar panel / fuel cell

Typical areas of use for the use of batteries, street lights, solar panels, fuel cells or a combination of these will be where the supply of 220VAC is not possible or entails high costs or in connection with temporary work notices. An example of the use of a fuel cell could be a warning vehicle that is used when working on the road. A solution with a solar panel means that a solar panel is mounted on the sign box. The panel is connected to a rechargeable battery via a converter/regulator which controls the power draw from the panel and the charging of the battery.

When a road is closed, it must be possible to actively establish a symbol that is placed at the place that is/will be closed (planned closure). In the event of a planned closure, the date/time must also be able to be entered into the management system. The closed road symbol will be the guide for which signs (eg detours) are to be switched on. Scenarios for this are established for the sections where a diversion system is used. Programming this is done by the administrator of the system.

Claims (11)

1. Two-position sign comprising a sign box (1) with a transparent front plate (4), a back wall (2), and a reflective sign (7) mounted on the back wall (2) inside the sign box (1), characterized in that an LCD curtain is mounted inside the sign box (1) behind the front plate (4), the LCD curtain comprising a transparent plate (5) which is coated with an LCD foil (6) on the front surface and an LCD foil (7) on the rear surface, as both LCD foils with power supply can simultaneously be made to be transparent and thereby be completely transparent, or without power supply not to be transparent and thereby be opaque. 2. Two-position sign according to claim 1, where the transparent plate with the glued foils (5) is at least 15 mm thick to prevent light escaping/"leaking" through the front LCD foil when it is not transparent (6 ), is stopped by the rear LCD foil (7). 3. Two-position sign according to claim 2, where the transparent plate is preferably 15 mm thick or more. 4. Two-position sign according to claim 1, where the sign box (1) is a total of 10 - 15 cm deep. 5. Two-position sign according to claim 1, further comprising one or two light sources (9) inside the sign box. 6. Two-position sign according to claim 1, further comprising a heating foil glued to the inside of the front plate. 7. Two-position sign according to claim 1, further comprising a foil glued to the outside of the front plate which helps dirt run off when it rains. 8. Two-position sign according to claim 1, further comprising a control unit (11) arranged to receive control signals via a wired (17) Ethernet or wireless communication connection (16, 18), the control unit being connected to the LCD foils (6, 7 ) and controls these on or off. 9. Two-position sign according to claim 8, where the communication connection is a Bluetooth, WiFi, mobile phone or mobile radio connection. 10. Two-position sign according to claim 8, further comprising a GPS receiver (15) which is connected to the control unit (11). 11. Two-position sign according to claim 5, further comprising a weather station (13) arranged to measure temperature, humidity, wind speed and amount of precipitation, the weather station being connected to the control unit (11).