WO1997048090A1

WO1997048090A1 - A visual display unit

Info

Publication number: WO1997048090A1
Application number: PCT/GB1997/001578
Authority: WO
Inventors: Martin James Wild; Martin Bull
Original assignee: Universal Destinations Limited
Priority date: 1996-06-12
Filing date: 1997-06-11
Publication date: 1997-12-18
Also published as: AU3042897A; GB2314190A; GB9612239D0

Abstract

A visual display unit such as may be used to indicate the destination or route number of a passenger vehicle comprises a casing (1) defining a window area (5) through which a portion of a blind (6) bearing visually presented information is visible from the exterior of the casing (1). Two guide rollers (10) are located within the casing (1) and are each positioned at one of two opposed sides of the window area (5), respectively. The blind (6) passes over the guide rollers (10) and its ends are wound around the two spool rollers (8, 9) which are also located within the casing (1). An endless drive belt (11) driven by a drive means (14) contacts a predetermined length of the blind (6) to move the blind (6) frictionally over the guide rollers (10) from one spool roller (8, 9) to the other (9, 8) and vice versa as the drive belt (11) is itself driven thereby to change the information visible in the window area (5). Preferably, the drive belt (11) has an elastic nature whereby at least that portion of the blind (6) which is visible in the window area (5) is tensioned and held substantially taut as the blind is moved by the belt (11).

Description

A VISUAL DISPLAY UNIT

The present invention relates to a visual display unit such as may be used to indicate the destination or route number of a passenger vehicle.

Conventionally, destination and route number indicators comprise a back-lit blind bearing appropriate information, such as place names or numbers, that is wound around a pair of spaced rollers between which a desired message is displayed. In most cases, the route number indicator comprises a bank of three blinds which each display one digit of the number thereby permitting any three digit number to be displayed. Such an arrangement is called a "triple route number" display or TRN. In order to change the display, typically each blind is wound in either direction from roller to roller by means of a winder which is linked to the rollers by bevel gears and lightly sprung dog clutches. Tension is kept on the blind by means of friction washers placed at the ends of each roller. In the case of a TRN, the need for three winders is alleviated by means of a gearbox mechanism which permits one winder to be used sequentially for each blind.

In passenger vehicles such as buses, several destination indicators and TRN displays are usually located on each bus. When it is desired to change the display, whilst some of the display units may be mechanized it is still common for the bus driver to have to wind on blinds by hand. This is time consuming and tends to result in the driver failing to change all of the displays.

In order to overcome these problems with display units incorporating blinds, electronic display units have been produced which use a multiplicity of illuminated spots to form individual letters and numbers and thereby spell out a destination name or route number. However, the problem with such displays is that they are difficult to read, particularly by elderly persons and those with impaired vision. Blinds, which can be constructed so as to display a bright, clearly visible message, are preferable to electronic displays from this point of view.

It is an object of the present invention to provide a visual display unit which incorporates a blind, and therefore the visual advantages of this type of display, but in which the display can be changed mechanically in a simpler more efficient fashion than conventional units incorporating blinds.

According to a first aspect of the present invention there is provided a visual display unit comprising a casing defining a window area and locating two guide rollers, each positioned within the casing at one of two opposed sides of the window area respectively; a blind passing over the guide rollers and bearing visually presented information which is visible from the exterior of the casing in the window area; and characterised in that it also comprises two spool rollers around which respective ends of the blind are wound; an endless drive belt which contacts a predetermined length of the blind to move the blind frictionally over the guide rollers from one spool roller to the other and vi ce versa as the drive belt is itself driven thereby to change the information visible in the window area; and a drive means for the drive belt.

Preferably, the drive belt contacts the external portions of the blind which are exposed around the periphery of the spool rollers to move the blind frictionally over the guide rollers from one spool roller to the other and vi ce versa .

Preferably also, the drive belt has an elastic nature whereby at least that portion of the blind which is visible in the window area is tensioned and held substantially taut as the blind is moved by the belt.

Advantageously, two drive belts driven synchronously by the same drive means are provided to move the blind frictionally from one spool roller to the other.

Preferably also, a tensioning means is provided for the blind in combination with each of the spool rollers whereby each spool roller is free to rotate in a first direction but is impeded from rotational movement in the opposite direction.

Preferably also, each tensioning means comprises a pivotally mounted arm, one end of which is biassed into engagement with a notched cam attached to one of the spool rollers.

Preferably also, the pivotal arms in contact with the two notched cams are biassed by two torsion springs respectively, said two springs being wound in opposite directions to one another.

Preferably also, the drive means preferably comprises a motor which drives one of a series of rollers over which the drive belt rides. Preferably, the drive belt passes over three rollers, one of which comprises the driven roller.

Advantageously, the motor and the rollers of the drive means are attached to at least one plate which can be snap-fitted into the casing. Preferably, the act of inserting the drive mechanism into the casing tensions the drive belt against the blind.

Preferably also, the casing comprises at least one transparent conduit to accommodate a luminaire for the illumination of the blind.

Advantageously, the display unit additionally comprises a sensor arrangement capable of transmitting and receiving light and a control means which is linked to an output of the sensor arrangement and to the drive means, and the blind defines at least one hole at a predetermined position relative to at least two separate displays on the blind, the sensor arrangement being located so as to shine light on the blind whereby said one or more holes in the blind can be detected and the control means can operate to control movement of the blind to alter the display visible in the window area.

Preferably also, the blind moves over a roller which is provided with a reflective surface and the sensor arrangement is positioned adjacent the roller whereby light emitted by the sensor is reflected back thereto when a portion of the blind defining one of said holes is in contact with the roller.

Alternatively, the blind is passed between transmitting and receiving portions of the sensor arrangement whereby the emitted light can only be detected by the receiving portion of the sensor arrangement when a portion of the blind defining one of said holes in the blind is passing through the sensor arrangement.

Preferably also, the sensor arrangement comprises a transmitting and receiving LED arrangement. Preferably also, the transmitted light comprises either modulated or pulsed light.

The present invention will now be described by way of example with reference to the accompanying drawings, in which:-

Fig. 1 is a side elevation of a first embodiment of visual display unit according to the invention shown with a side wall of the casing of the unit removed;

Fig. 2 is front elevation of the unit shown in Fig. 1 with both the front wall of the casing and the blind of the unit removed in order to show its interior construction;

Fig. 3 is a view similar to Fig. 1 of a modified display unit;

Fig. 4 is a side elevation similar to Fig. 1 but of a second embodiment of visual display unit according to the invention;

Fig. 5 is front elevation of the unit shown in Fig. 4 with the blind of the unit removed in order to show its interior construction; and

Fig. 6 is a detail of part of the unit shown in Fig. 5 to an enlarged scale.

In the drawings, similar elements of both the first and second embodiments of the visual display unit and of the modified first embodiment shown in Fig. 3 are referred to using the same reference numerals.

The first embodiment of visual display unit shown in the drawings comprises a casing 1 with front, side and rear walls 2, 3, 4 respectively. The front wall 2 defines a window area 5 which may comprise simply an opening or an opening in which is fitted a transparent sheet material through which can be seen a portion of a blind 6. The rear wall 4 of the casing 1 either comprises a hinged door or is otherwise removable to provide access into the casing 1.

Preferably in this embodiment, the casing 1 is made of a blown cast plastics material in two halves which are joined centrally from front to back.

The blind 6 can be made of any suitable sheet material such as is currently used for visual display units such as destination indicators and the like. Typically such material comprises a non-woven fibrous sheet material which is not easily torn nor stretched and yet can be readily printed or otherwise provided with visual information, typically in the form of words or numbers. Such blinds too are typically at least semi-transparent in the areas covered by the letters and numbers so that they can be lit from behind to illuminate the message it is desired to display. To this end, the casing 1 is provided with two transparent cylindrical conduits 7 adjacent the window 5. These conduits can be used to house fluorescent tubes or similar luminaires to enable that portion of the blind 6 visible through the window to be back-lit when required.

The ends of the blind 6 are wound around two spool rollers 8, 9 which according to the direction in which the blind 6 is moved comprise supply and take-up spools respectively or vice versa.

In order to assist in tensioning that portion of the blind 6 visible through the window 5, two guide rollers 10 are located at each side of the window 5 and around which the blind 6 passes. The rollers 10 are arranged parallel to the top and bottom front edges of the casing 1.

During construction of the unit, the guide rollers 10 and the spool rollers 8, 9 are inserted into the assembled casing. The ends of the blind 6 are then attached respectively to the spool rollers 8 and 9, for example by means of double-sided adhesive tape, ensuring that the information on the blind 6 is being correctly displayed via the window 5. The blind 6 is then manually wound partially onto each roller 8, 9.

Unlike conventional display units wherein to change the message being displayed the rollers holding the blind are driven, in the present invention it is the blind 6 itself which is driven frictionally by means of a drive belt 11 which passes over three rollers 12 and 13, which may be barrelled. Two of these rollers 12 are freely rotatable but the third roller 13 is driven by means of a motor 14. In the first embodiment shown in Figs. 1 to 3 , the rollers 12 and 13 together with the motor 14 are attached to a back plate 15 via brackets 16. The back plate 15 may comprise the rear wall 4 of the casing or can otherwise be removably snap-mounted inside the rear of the casing 1. In the second embodiment shown in Fig. 4, the motor 14 is located within a housing 21 attached within the rear of the casing in order to close same. It will be appreciated, therefore, that during construction of the unit, the drive mechanism as a whole is pre-assembled and then inserted into the rear of the casing 1 after the blind 6 has been wound around the spool rollers 8,9 and the guide rollers 10..

In both embodiments, the driven roller 13 and the motor 14 are located substantially centrally of the sides of the casing 1 between the spool rollers 8 and 9. The undriven rollers 12 however are located adjacent the top and bottom rear edges of the casing 1, parallel with the guide rollers 10.

The rollers 12 and 13 are arranged and spaced so that the belt 11 is forced into contact with the external portions of the blind 6 which are exposed around the periphery of the spool rollers 8 and 9. The act of inserting the drive mechanism into the casing 1 tensions the drive belt 11 against the blind 6 wound around the spool rollers 8 and 9. As can be seen in Fig. 1, when the blind 6 is predominantly wound onto the upper, say supply, spool 8, then the length of belt 11 forced into contact with the blind 6 wound around this spool 8 is considerably greater than that forced into contact with that portion of the blind 6 wound around the take-up spool 9. However, as the blind is driven from the spool 8 to the spool 9, the length of belt 11 in contact with the blind 6 wound around the spool 8 gradually decreases as the corresponding length of belt 11 in contact with the blind 6 wound around the spool 9 increases. At any given time, however, the total length of the drive belt 11 in contact with the blind 6 is substantially constant.

The blind 6 is tensioned over the guide rollers 10 as it passes the window 5 by means of the belt 11, which for this purpose must have a substantially elastic nature, for example by being made of a synthetic or natural rubber rather than webbing. The belt 11 must also pass over an odd number, preferably three, rollers 12, 13. When the motor 14 is driven in either direction, the elasticity of the belt 11 ensures that the parts of the belt 11 between the drive roller 13 and the other rollers 12 are either stretched or compressed depending on whether that particular section of the belt is being "pulled" or "pushed". This has the effect of tensioning that portion of the blind 6 being wound around the take-up spool more than that being unwound from the supply spool. For example, as the belt 11 is driven in a clockwise direction as viewed in Fig. 1, the initial drag imparted to it by the drive roller 13 causes that portion of it about to be driven over the roller 13, namely that between the upper roller 12 and the roller 13, to stretch slightly and thus impart a greater impetus to that portion of the blind 6 in contact therewith and to turn the spool 8, the take-up spool in this instance, about which it is wound with a slightly greater peripheral speed than the spool 9. This produces sufficient tension in the blind 6 to ensure that that portion of it which is pulled into view through the window 5 is held taut. The same effect occurs with spool 9 when the blind is wound in the opposite direction.

Referring now to Fig. 3, in the modification shown therein, the casing 1 is extended by a projecting portion 17 which permits the height or width of the window area 5 to be considerably increased. The guide roller 10 adjacent the portion 17 is displaced to the end thereof and a third guide roller 18 is located on the opposite side of the blind 6 within the bounds of the original casing 1 to ensure that the blind 6 does not contact and therefore cannot be fretted by the casing 1.

It will be appreciated that the display unit of the invention can be modified in other similar ways to increase or decrease the size of the window 5, either by physically making the unit itself smaller or larger or by varying the size and shape of the window. In the latter case appropriate numbers of guide rollers 10 can be provided for this purpose. In addition, the unit can be constructed so that the blind 6 can move upwardly or downwardly, or from side to side as appropriate. If the blind 6 is to run from side to side of the window 5, it is preferable for the guide rollers 10 to be barrelled to prevent unnecessary friction at the ends of the rollers from fretting the blind 6.

As the visual information presented on the blind 6 comprises a sequence of discrete pieces of information which are displayed independently of one another to the public via the window. It is therefore necessary to ensure that the required piece of information is displayed correctly at any given time. In order to accomplish this electronically, between each of the separate displays on the blind 6 can be punched either a hole or a series of holes forming a code identifying the display adjacent to it. It will be appreciated that these holes or series of holes are always a predetermined distance apart on the blind 6, this distance being determined by the size of the window 5 and the spacing allotted between sequential displays .

The holes in the blind 6 are detected and the codes may be read by a sensor arrangement 19 which is located in an aperture 20 of the casing adjacent one of the guide rollers 10. The sensor arrangement 19, for example a transmitting and receiving LED arrangement, shines pulsed or modulated light on to that portion of the blind 6 passing over the roller 10 at the position where the codes are located. Preferably, the roller 10 is silvered or otherwise covered with a reflective material such that when one of the pierced portions of the blind passes over it, the pulsed or modulated light is reflected back to the sensor arrangement 19 where it is detected. It is therefore possible to determine when a piece of information displayed on the blind 6 is correctly aligned with the window. Thus, by means of a controller (not shown) linked to an output of the sensor arrangement 19 and in turn linked to the motor 14, it is possible to detect and store the position of the blind at any given time and, by knowing the sequence of information displayed on the blind 6 to drive the blind 6 via the motor 14 in the correct direction to change it to a new predetermined display position.

It is advantageous to use a hole or series of holes to tag the various displays on the blind 6 because such holes are permanent and cannot be marred in the same way as printed codes, which tend to become obscured by dirt in use. In addition, the provision of the reflective surface on one of the guide rollers 10 ensures that this surface remains bright and shiny in use as is constantly being polished by the action of the blind 6 passing over it.

The second embodiment of the present invention as shown in Figs. 4 to 6 will now be described in more detail where it differs from that of the first. Equivalent elements of the two constructions will be referred to using the same reference numerals.

The visual display unit of this embodiment again comprise a casing 1 but here the casing 1 simply comprises two side plates 22 between which is connected at least one support rod 23 in addition to the spool rollers 8, 9 and the guide rollers 10. The window area therefore forms the whole area defined between the side plates 22 and the guide rollers 10.

In this embodiment, the conduits 7 for use in back¬ lighting the blind 6 have been omitted; the blind is back- lit but from the rear of the casing 1.

Two synchronously driven drive belts 11 are used to move the blind 6 into the required position. Both of the belts 11 are driven by the same drive roller 13 which is powered by a motor 14 around the two further rollers 12.

However, in this embodiment as previously mentioned, the motor 14 is located within the housing 21 and drives the driven roller 13 via a drive belt 24 which passes over a pulley 25 rigidly attached to the roller 13. The brackets 16 are also replaced by appropriately shaped side plates 26 which also form part of the housing 21. These side plates 26 of the housing 21 simply connect respectively to the two side plates 22 at the rear of the casing 1, preferably by a snap-fit means. As in the first embodiment, the drive mechanism comprises a unit made up of the rollers 12, 13, the motor 14 with its housing 21 and the drive belts 11 and 24.

In order to prevent slippage of the drive belts 11 along the rollers 12 and 13 in use, the portions of the roller 13 over which the drive belts 11 pass are barrelled as indicated at 27.

As in the first embodiment, the blind 6 is tensioned over the guide rollers 10 by means of the drive belts 11, which for this purpose are elastic in nature as previously described. However, an additional tensioning means for the blind 6 is also provided in this embodiment. Arms 28 are pivotally mounted at one end to one of the side plates 22 and their free ends are biassed via torsion springs 29,30 into contact with cams 31, 32 located around the central shafts of the spool rollers 8 and 9 respectively. The cams 31 and 32 are attached to the spool rollers via spring clips and washers (not shown) and are each also provided with a notch in which the end of the respective arm 28 can lodge in one direction of rotation of the cam 31, 32. In this way rotation of the spool rollers 8, 9 is free in one direction but is impeded in the opposite direction by frictional interaction between the cams 31,32 with the ends of the spool rollers 8, 9 respectively, in order to prevent unwinding of the rollers 8 and 9 in the opposite direction to that required. As in use, the spool rollers 8 and 9 rotate in the same direction but with one spool being the supply spool and the other being the take-up spool, the action of the respective cams 31, 32 and torsion springs 29, 30 are arranged to operate in opposite directions. For example, the torsion springs 29, 30 are coiled in opposite directions. In the arrangement shown in Figs. 4 and 5 the upper spring 29 is arranged to have a left-hand coil whereas the lower spring 30 is arranged to have a right- hand coil. Thus the elastic nature of the drive belts 11 and the action of the biassed arms 28 and cams 31, 32 all act together to keep the blind 6 taut both during spooling and when stationary in any given position.

The position of the blind 6 is detected and controlled by means of a sensor arrangement 19 which detects appropriate holes punched in the blind 6 in a similar manner to that previously described. However, in this embodiment, two such sensor arrangements 19, which may again be transmitting and receiving LED arrangements, are provided at each side of the blind 6 respectively. Here also, the sensor arrangements 19 are located on opposite sides of and centrally of the window area and edges of the blind 6 are arranged to pass between the transmitting and receiving portions of the sensor arrangement 19 whereby holes punched in the edges of the blind can be detected. In this way it is not a requirement that the transmitted light be reflected back through a hole in the blind but simply that the emitted light pass through a hole from the transmitter to the receiver of the sensor arrangement. As before, the holes punched in the blind 6 can comprise single holes or a series of holes forming a code identifying the display adjacent to it.

Thus, by linking the display units as described above with reference to all the drawings to suitable electronic controllers, the display shown by a unit can be altered as desired simply by entering an appropriate code or name into the controller. As each blind 6 has its own drive mechanism, several display units employed, for example in the same vehicle, can be changed simultaneously without any manual effort other than, for example, the entry of a code into a keypad. In the case of public service vehicles such as buses, it is usual for the driver to enter appropriate details such as the route number into his ticket machine at the start of each journey. Such information can, therefore, be used to change the displays of all the display units in the vehicle automatically.

It will be appreciated that whilst the unit of the present invention is particularly suited for use in indicating the destinations and route numbers of vehicles, it may also be used for a similar purpose outside the vehicles themselves in depots, stations and airports. In addition, it could also be used to display advertising material in any suitable location, the drive means being controlled so that the advertisement being displayed changes on a regular basis.

Claims

1. A visual display unit comprising a casing (1) defining a window area (5) and locating two guide rollers (10) , each positioned within the casing (1) at one of two opposed sides of the window area (5) respectively; a blind (6) passing over the guide rollers (10) and bearing visually presented information which is visible from the exterior of the casing (1) in the window area (5); and characterised in that it also comprises two spool rollers (8,9) around which respective ends of the blind (6) are wound; an endless drive belt (11) which contacts a predetermined length of the blind (6) to move the blind (6) frictionally over the guide rollers (10) from one spool roller (8,9) to the other (9,8) and vi ce versa as the drive belt (11) is itself driven thereby to change the information visible in the window area (5) ; and a drive means (14) for the drive belt (11).

2. A unit as claimed in Claim 1, characterised in that the drive belt (11) contacts the external portions of the blind (6) which are exposed around the periphery of the spool rollers (8,9) to move the blind (6) frictionally over the guide rollers (10) from one spool roller (8,9) to the other (9,8) and vice versa .

3. A unit as claimed in Claim 1 or Claim 2, characterised in that the drive belt (11) has an elastic nature whereby at least that portion of the blind (6) which is visible in the window area (5) is tensioned and held substantially taut as the blind (6) is moved by the belt (11).

4. A unit as claimed in any one of Claims 1 to 3, characterised in that two drive belts (11) driven synchronously by the same drive means (14) are provided to move the blind frictionally from one spool roller (8,9) to the other (9,8) .

5. A unit as claimed in any one of Claims 1 to 4, characterised in that tensioning means (28,29,30,31,32) are provided for the blind (6) in combination with each of the spool rollers (8,9) whereby each spool roller (8,9) is free to rotate in a first direction but is impeded from rotational movement in the opposite direction.

6. A unit as claimed in Claim 5, characterised in that each tensioning means comprises a pivotally mounted arm (28) , one end of which is biassed into engagement with a notched cam (31,32) attached to one of the spool rollers (8,9).

7. A unit as claimed in Claim 6, characterised in that the pivotal arms (28) in contact with the two notched cams (31,32) are biassed by two torsion springs (29,30) respectively, said two springs (29,30) being wound in opposite directions to one another.

8. A unit as claimed in any one of Claims 1 to 7, characterised in that the drive means (14) comprises a motor which drives one (13) of a series of rollers (12,13) over which the drive belt (11) rides.

9. A unit as claimed in Claim 8, characterised in that the drive belt (11) passes over three rollers (12,13) , one of which comprises the driven roller (13) .

10. A unit as claimed in Claim 8 or Claim 9, characterised in that the motor (14) and the rollers (12,13) of the drive means are attached to at least one plate (15,22) which can be snap-fitted into the casing (1) .

11. A unit as claimed in any one of Claims 1 to 10, characterised in that the act of inserting a drive mechanism, comprising the drive belt (11) and the drive means (14) , into the casing (1) tensions the drive belt (11) against the blind (6).

12. A unit as claimed in any one of Claims 1 to 11, characterised in that the casing (1) comprises at least one transparent conduit (7) to accommodate a luminaire for the illumination of the blind.

13. A unit as claimed in any one of Claims 1 to 12, characterised in that the display unit additionally comprises a sensor arrangement (19) capable of transmitting and receiving light and a control means which is linked to an output of the sensor arrangement (19) and to the drive means (14) , and in that the blind (6) defines at least one hole at a predetermined position relative to at least two separate displays on the blind (6), the sensor arrangement (19) being located so as to shine light on the blind (6) whereby said one or more holes in the blind (6) can be detected and the control means can operate to control movement of the blind (6) to alter the display visible in the window area.

14. A unit as claimed in Claim 13, characterised in that the blind (6) moves over a roller (10) which is provided with a reflective surface and the sensor arrangement (19) is positioned adjacent the roller (10) whereby light emitted by the sensor arrangement (19) is reflected back thereto when a portion of the blind (6) defining one of said holes is in contact with the roller (10).

15. A unit as claimed in Claim 13, characterised in that the blind (6) is passed between transmitting and receiving portions of the sensor arrangement (19) whereby the emitted light can only be detected by the receiving portion of the sensor arrangement (19) when a portion of the blind (6) defining one of said holes in the blind is passing through the sensor arrangement (19) .

16 A unit as claimed in any one of Claims 13 to 15, characterised in that the sensor arrangement (19) comprises a transmitting and receiving LED arrangement.

17. A unit as claimed in any one of Claims 13 to 16, characterised in that the transmitted light comprises either modulated or pulsed light.