WO2016025982A1

WO2016025982A1 - Improved signal system

Info

Publication number: WO2016025982A1
Application number: PCT/AU2015/000493
Authority: WO
Inventors: Kevin John FAIRMAN
Original assignee: Fairman Dent International Pty Ltd
Priority date: 2014-08-18
Filing date: 2015-08-17
Publication date: 2016-02-25

Abstract

An improved signal system (10) for providing information to motorists and/or pedestrians, the signal system (10) comprising: an LCD panel (12) comprising a shutter (or shutters) (14) adapted to be switched between a first condition, in which the shutter (14) is substantially opaque, and a second condition, in which the shutter (14) is substantially transparent. The signal system (10) further comprises a reflective surface (16) arranged immediately behind the LCD panel (12), the reflective surface (16) being adapted to reflect light incident thereon through the LCD panel (12) when the shutter (14) is in the second condition. The signal system (10) further comprises a plurality of LED lights (18) provided in association with the LCD panel (12), adjacent to and operative with the shutter (14), wherein, in use, the signal system (10) can provide the required information to an observer whether in ambient light or other light incident on the reflective surface (16) or in darkness.

Description

"IMPROVED SIGNAL SYSTEM"

Field of the Invention

The present invention relates to an improved signal system and relates particularly, though not exclusively to improvements in indicator signals on motor vehicles, as well as to traffic signals.

Background to the Invention

Prior art traffic signals used to employ incandescent light globes behind green, amber and red filters to produce three types of signal in response to an electrical control signal. One problem with incandescent light globes is that when the globe fails the signal no longer operates. More recently this arrangement has been widely replaced with LED traffic signals in which a large number of LEDs are arranged in a circular array to give an appearance similar to traditional traffic signals. If several LEDs fail the signal as a whole will continue to operate due to redundancy. Furthermore, even though the LED array is often brighter than a traditional incandescent signal, the power- consumption of an LED signal is considerably lower than an incandescent signal. However, as with the traditional incandescent signals, in bright sunlight or other strong incident light, it is difficult to see LED signals and to distinguish which colour is being indicated. Furthermore in the event of a power failure both incandescent and LED signals cease to provide any indication of the required information.

Similar problems arise with the indicator signals on a motor vehicle. Traditionally the indicators on a vehicle used incandescent light globes behind amber and red filters to produce two types of signal, e.g. a brake signal, or turning signal. Increasingly vehicle indicator signals are being replaced with LED signals by motor vehicle manufacturers. However, with both traditional incandescent indicator signals and LED indicator signals, it is difficult to see the signal and/or to distinguish which colour is being indicated in bright sunlight or other strong incident light. The present invention was developed with a view to providing an improved signal system, using a combination of LCD and LED technology, which is less susceptible to the problems of prior art signals noted above. It will be appreciated that the invention can also be used in other types of signage and is not limited in its application to traffic signals or vehicle signals.

References to prior art in this specification are provided for illustrative purposes only and are not to be taken as an admission that such prior art is part of the common general knowledge in Australia or elsewhere.

Summary of the Invention

According to one aspect of the present invention there is provided an improved signal system for providing information to motorists and/or pedestrians, the signal system comprising: an LCD panel comprising a shutter adapted to be switched between a first condition, in which the shutter is substantially opaque, and a second condition, in which the shutter is substantially transparent; a reflective surface arranged immediately behind the LCD panel, the reflective surface being adapted to reflect light incident thereon through the LCD panel when the shutter is in the second condition; and, a plurality of LED lights provided in association with the LCD panel, adjacent to and operative with the shutters; wherein, in use, the signal system can provide the required information to an observer whether in ambient light or other light incident on the reflective surface or in darkness. Preferably the shutter is one of a plurality of shutters in the LCD panel arranged to provide a measure of redundancy whereby, in use, the signal system will continue to function adequately in the event that a shutter fails. Alternatively the LCD panel may comprise a single shutter. Preferably the LED lights are arranged in close proximity to the shutter wherein, in use, some of the light emitted from the LED lights is also reflected from the reflective surface when the shutter is in the second condition.

Preferably the LED lights are provided integral with the LCD panel, adjacent to and operative with the one or more shutters. Alternatively, the LED lights are mounted spaced apart from the LCD panel, such as in front of the LCD panel. Advantageously the LCD panel is provided in the form of a reflector and the LED lights are mounted centrally of the LCD panel.

Preferably the LCD panel comprises liquid crystals selected from the group comprising IBN (Improved Black Nematic), iSTN (Improved Super Twisted Nematic), TN (Twisted Nematic), HTN (High Twist Nematic), STN (Super Twist Nematic), FSTN (Film Compensated Twisted Nematic), DSTN (Double Super Twist Nematic), CSTN (Colour Super Twist Nematic), ChLCD (Cholesteric Liquid Crystal Display), LCD Shutter, ADLCDS (Active Domain LCD Shutter).

Preferably the reflective surface is in the form of a transflective panel. The reflective surface may be coloured so that when incident light is reflected therefrom it will be visible to the observer in that colour.

In one form of the invention, a backlight panel may be arranged immediately behind the transflective panel, so that when ambient light conditions are poor, the backlight panel wili provide light that is transmitted through the transflective panel so as to be visible to an observer when the shutters are in the second condition.

Throughout the specification, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers. Likewise the word "preferably" or variations such as "preferred", will be understood to imply that a stated integer or group of integers is desirable but not essential to the working of the invention. Brief Description of the Drawings

The nature of the invention will be better understood from the following detailed description of specific embodiments of the signal system, given by way of example only, with reference to the accompanying drawings, in which: Figures 1 a and 1 b illustrate an embodiment of an improved signal system in accordance with the present invention, comprising an LCD panel and LED combination in an ON condition and an OFF condition respectively;

Figure 2 illustrates a first embodiment of an improved signal system in accordance with the invention in the form of a indicator signals at the rear of a motor vehicle, showing the signals in an ON condition;

Figure 3 illustrates the improved signal system of Figure 2 showing the indicator signals at the rear of a motor vehicle in an OFF condition;

Figure 4 illustrates a side view of a second embodiment of an improved signal system in accordance with the present invention;

Figure 5 illustrates a front view of the second embodiment shown in Figure 4;

Figure 6 illustrates a top view of another embodiment of the manner in which the LED lights may be arranged in association with the LCD panel; and,

Figure 7 is a front view of the embodiment shown in Figure 6.

Detailed Description of Preferred Embodiments

A preferred embodiment of an improved signal system in accordance with the invention, as illustrated in Figures 1 to 3, comprises an improved signal system 10 for providing information to motorists and/or pedestrians. The signal system typically comprises an LCD panel and LED combination as illustrated in Figure 1. An LCD panel 12 comprising one or more shutters 14 is adapted to be switched between a first condition, (as shown in Figure b), in which the one of more shutters 14 are substantially opaque, and a second condition, {as shown in Figure 1a), in which the one of more shutters 14 are substantially transparent. A reflective surface 16 is arranged immediately behind the LCD panel 12, the reflective surface 6 being adapted to reflect light incident thereon through the LCD panel when the one or more shutters 14 are in the second condition.

The improved signal system 10 further comprises a plurality of LED lights 18 provided integral with the LCD panel 12, adjacent to and operative with the one or more shutters 14. The combination of both LCD shutter technology and LED technology where the LED actually protrudes through the LCD panel has not been done before.

In use, during daylight hours, whether in ambient light or other incident light, the LED lights will be visible and the reflective surface behind the LCD panel 12 will be visible when the shutters 14 are in the second condition. Alternatively, at night time, when there may be no ambient or incident light, the LED lights 18 will still be operative so that the signal system can provide the required information to an observer whether in strong incident light or in darkness. Some of the light from the LED lights 18 may also be reflected from the reflective surface 16, since the shutters 14 will simultaneously be in the second (substantially transparent) condition.

The LCD panel 12 preferably comprises a plurality of shutters 14, as shown in Figure 1 , in order to provide a measure of redundancy whereby, in use, the signal system 10 will continue to function adequately in the event that a shutter 14 fails. Alternatively the LCD panel 12 may comprise a single shutter 14.

A liquid crystal display (LCD) is a thin electronic display device that uses the light modulating properties of liquid crystals to display information. Liquid crystals do not emit light directly, but rather are used to control the transmission of light. Each pixel of an LCD typically consists of a layer of liquid crystal molecules aligned between two electrodes made from a transparent conductor such as Indium Tin Oxide, and two light polarizing filters. The axes of transmission of the polarizing filters are generally perpendicular to each other. In the absence of liquid crystal molecules between the polarizing filters, light passing through the first filter would be blocked by the second (cross-polarised) filter. Various types of liquid crystals may be used in the LCD panel of the present invention, including but not limited to the following: IBN (Improved Black Nematic), iSTN (Improved Super Twisted Nematic), TN (Twisted Nematic), HTN (High Twist Nematic), STN (Super Twist Nematic), FSTN (Film Compensated Twisted Nematic), DSTN (Double Super Twist Nematic), CSTN (Colour Super Twist Nematic), ChLCD (Cholesteric Liquid Crystal Display), LCD Shutter, ADLCDS (Active Domain LCD Shutter). Alternatively, electronic paper may be used as a light shutter, for example EPD (Electronic Paper Display).

Before an electric field is applied to the LCD, the orientation of the liquid crystal molecules is determined by the alignment at the surfaces of the electrodes. In a twisted nematic device (the most common LCD device), the directions of the alignment surfaces of the two electrodes are perpendicular to each other. Therefore the molecules arrange themselves in a helical structure, or twisted orientation. This reduces the rotation of the polarization of the incident light, and the pixel appears grey. If the applied voltage is large enough, the liquid crystal molecules between the layers are almost completely untwisted. In this situation the polarization of the incident light is not rotated as it passes through the liquid crystal layer. The light will then be mainly polarized (by the first filter) perpendicular to the second filter, and thus be blocked and the pixel will appear substantially black. By controlling the voltage applied across the liquid crystal layer in each pixel, light can be allowed to pass through in varying amounts thus constituting different levels of grey.

This ability to switch a pixel in an LCD between a first condition, in which the pixel is substantially opaque, and a second condition, in which the pixel is substantially transparent, is exploited in the present invention. The pixel essentially functions as a shutter, blocking the transmission of light in the first condition, and permitting the transmission of light in the second condition. Therefore the LCD pixels will be referred to as shutters 14 throughout the specification. The signal system 10 further comprises a reflective surface 16 arranged immediately behind the LCD panel 12. The reflective surface 16 is adapted to reflect light incident thereon through the LCD panel 12 when the shutters 14 are in the second condition, i.e. substantially transparent. In use, the signal system 10 can provide the required information to an observer, such as a driver of a vehicle or a pedestrian, in either ambient light conditions or as a result of other light which is incident on the reflective surface 16, such as the light of vehicle headlights. Typically the reflective surface 16 is coloured so that when the incident light is reflected there from it will be visible to the observer in that colour. The state of the shutters 14 is determined by an electric field which is applied to the LCD panel 12 in response to an electric control signal from a controller (not shown). Depending on the arrangement of the liquid crystal layer relative to the polarising filters, the application of the electric field may switch the shutters 14 to either the first or second condition, in some applications it may be preferable for the shutters 14 to remain in the first condition (substantially opaque) in the absence of power, and in other applications it may be preferable for the shutters 14 to remain in the second condition (substantially transparent) in the absence of power.

Figures 2 and 3 illustrated an application of the signal system 10 to the left and right taillights of a motor vehicle 20. in Figure 2, the driver has depressed the brake pedal and the vehicle light controller has applied appropriate electric signals to the LCD panel 12 and the LED lights 18. In this embodiment the shutters 14 are switched to the second condition (substantially transparent) when an electric signal is applied to the LCD panel 12. Hence the reflective surface 16 behind the pane! 12 is visible, !n this application, the reflective surface 16 behind the top four rows of shutters 14 of the left and right indicator signals is coloured red, to indicate the vehicle is slowing or stopped. The reflective surface 16 behind the bottom two rows of shutters 14 of the left and right indicator signals is amber (or orange), since this part of the signal system 10 is typically also used as turn signals. In this embodiment, the signal system 10 also comprises an LCD panel 12 with a single row of shutters 14 and associated LED lights 18 provided in a horizontal brake indicator signal bar 22 on the rear spoiler 24 of the vehicle. The reflective surface 16 behind the row of shutters 14 of the brake indicator signal bar 22 is coloured red, to provide a further indication that the vehicle 20 is slowing or stopped.

At the same time as the vehicle light controller applies an electric signal to the LCD panel 12 it also applies an electric signal to the LED lights 18, causing them to be simultaneously illuminated. Although more difficult to see in Figure 2, the LED lights 18 are arranged adjacent to and in close proximity to each shutter 14 of the LCD panel 12 (similar to Figure 1). The LED lights 18 are preferably of the same colour as the reflective panel 16 behind the shutters 14 to which they're adjacent to. Hence the LED lights 18 adjacent to the top four rows of shutters 14 are all coloured red, whereas the LED lights 18 adjacent to the bottom two rows of shutters 14 are all coloured amber. The LED lights 8 adjacent to the single row of shutters 14 in the brake indicator signal bar 22 are all coloured red. Advantageously, some of the light emitted by the LED lights 18 will also be reflected from the reflective surface 16 through the adjacent shutters 14.

Typically, when no electric signal is applied to the signal system 10, the shutters 14 will all be in the first condition (substantially opaque), and the LED lights 18 will all be OFF. The taillights will then appear as shown in Figure 3. If the driver of the vehicle 20 operates the left turn indicator signal, the vehicle light controller will send intermittent electric signals to the bottom two rows of shutters 14 and the adjacent LED lights 18, of the left indicator signal of the vehicle. This intermittent electric signal will switch the shutters 14 between the first and second conditions, whilst simultaneously switching the LED lights 8 ON and OFF. The net effect is an intermittent amber signal, indicating to an observer that the driver intends to turn left. The turn signal will be clearly visible in both high incident light conditions and in darkness, as well as normal daylight conditions. In some situations the incident light is not sufficiently bright to permit the reflective surface 16 to be clearly visible in ambient light conditions. Therefore, in addition to the provision of the LED lights 18, it may be preferable to also provide the improved signal system with the facility to be backlit. As with the previous embodiment, such a signal system comprises an LCD panel 12 having one or more shutters 14 adapted to be switched between a first condition, in which the one or more shutters 14 are substantially opaque, and a second condition, in which the one or more shutters 14 are substantially transparent.

This signal system also comprises a reflective surface 16 arranged immediately behind the LCD panel 12. The reflective surface 16 in this embodiment is in the form of a transflective panel. As with the previous embodiment, the transflective panel is adapted to reflect light incident thereon through the LCD panel 12 when the shutters 14 are in the second condition, i.e. substantially transparent. However the transflective panel is itself also translucent so that when backlit it transmits light through itself of the same colour as it reflects. Transflective materials are commonly used in LCD devices to permit the display to be read under all lighting conditions.

Advantageously this signal system further comprises a backlight panel arranged immediately behind the transflective panel. When ambient light conditions are poor, for example at dusk or night time, the backlight panel 24 will provide light that is transmitted through the transflective panel so as to be visible to an observer when the shutters 14 are in the second condition. If preferred, the signal system may be fitted with an illuminance sensor which senses the level of ambient light and switches ON the backlight panel once the ambient light falls below a preset threshold. A second embodiment of the invention of an improved signal system 30 in accordance with the invention is shown in Figures 4 and 5. The improved signal system 30 of the second embodiment is similar in many respects to the improved signal system 0 of the first embodiment. The improved signal system 30 comprises an LCD panel 32 having one or more shutters 34 (not visible in the drawings). A reflective surface 36 is arranged immediately behind the LCD panel 32, the reflective surface 36 being adapted to reflect light incident thereon through the LCD panel when the one or more shutters 34 are in the second condition. The improved signal system 30 further comprises a plurality of LED lights 38 provided on a clear (transparent) substrate 40. In the improved signal system 30 of the second embodiment, the LEDs 38 are mounted spaced apart from, or in front of, the LCD panel 32, as best shown in Figure 4. This is in contrast to the first embodiment where the LED lights 18 are provided integral with the LCD pane! 12, adjacent to and operative with the one or more shutters 4, so that the LEDs protrude through the LCD panel.

Figures 6 and 7 illustrate yet a third way in which one or more LED lights may be provided in association with the LCD panel of the invention. In this embodiment an LCD panel 50 is provided in the form of a reflector similar to that used in a torchlight, and one or more LED lights 52 are mounted centrally of the reflector. In this manner the light emitted by the LED lights 52 may be more effectively captured and reflected outwards to an observer.

Now that preferred embodiments of the improved signal system have been described in detail, it will be apparent that the described embodiments provide a number of advantages over the prior art, including the following:

(i) The combination of LCD and LED technologies covers all light conditions, from no light through to very high ambient/sunlight.

(ii) In addition, the LCD panel can run with little or no energy required. So, if this approach was used in say the light bar on the top of emergency service vehicles, then, during the day they could run for a very long time without the fear that the vehicle's battery will be run flat.

For signage over freeways or other areas that require high contrast but still visible at night, this approach could provide a low power approach. One that could easily run when there is no power available, only back-up battery supplies or solar power.

It will be readily apparent to persons skilled in the relevant arts that various modifications and improvements may be made to the foregoing embodiments, in addition to those already described, without departing from the basic inventive concepts of the present invention. For example, in the illustrated embodiments the shutters of the LCD panel are shown of hexagonal shape. However it will be apparent that the shutters may be of any suitable shape. Furthermore the pattern and configuration of the LED lights provided in close proximity to the shutters may also be quite different from that shown. For example, rather than being dispersed, as in the illustrated embodiments, the LED lights may be arranged in clusters or in an array of parallel rows and columns in close proximity to the shutters. Therefore, it will be appreciated that the scope of the invention is not limited to the specific embodiments described.

Claims

1. An improved signal system for providing information to motorists and/or pedestrians, the signal system comprising: an LCD panel comprising a shutter adapted to be switched between a first condition, in which the shutter is substantially opaque, and a second condition, in which the shutter is substantially transparent; a reflective surface arranged immediately behind the LCD panel, the reflective surface being adapted to reflect light incident thereon through the LCD panel when the shutter is in the second condition; and, a plurality of LED lights provided in association with the LCD panel, adjacent to and operative with the shutter; wherein, in use, the signal system can provide the required information to an observer whether in ambient light or other light incident on the reflective surface or in darkness.

2. An improved signal system as defined in claim 1 , wherein the shutter is one of a plurality of shutters in the LCD panel arranged to provide a measure of redundancy whereby, in use, the signal system will continue to function adequately in the event that a shutter fails.

3. An improved signal system as defined in claim 1 , wherein the LCD panel comprises a single shutter.

4. An improved signal system as defined in claim , wherein the LED lights are arranged in close proximity to the shutter wherein, in use, some of the light emitted from the LED lights is also reflected from the reflective surface when the shutter is in the second condition.

5. An improved signal system as defined in claim 2, wherein the LED lights are provided integral with the LCD panel, adjacent to and operative with the one or more shutters.

6. An improved signal system as defined in claim 2, wherein the LED lights are mounted spaced apart from the LCD panel.

7. An improved signal system as defined in claim 2, wherein the LCD panel is provided in the form of a reflector and the LED lights are mounted centrally of the LCD panel.

8. An improved signal system as defined in claim 1 , wherein the LCD panel comprises liquid crystals selected from the group comprising IBN (improved Black Nematic), ISTN (Improved Super Twisted Nematic), TN (Twisted Nematic), HTN (High Twist Nematic), STN (Super Twist Nematic), FSTN (Film Compensated Twisted Nematic), DSTN (Double Super Twist Nematic), CSTN (Colour Super Twist Nematic), ChLCD (Cholesteric Liquid Crystal Display), LCD Shutter, ADLCDS (Active Domain LCD Shutter).

9. An improved signal system as defined in claim 1 , wherein the reflective surface is coloured so that when incident light is reflected therefrom it will be visible to the observer in that colour.

10. An improved signal system as defined in claim 1 , wherein the reflective surface is in the form of a transflective panel.

11. An improved signal system as defined in claim 0, wherein a backlight panel is arranged immediately behind the transflective panel, so that when ambient light conditions are poor, the backlight panel will provide light that is transmitted through the transflective panel so as to be visible to an observer when the shutters are in the second condition.