GB2147444A

GB2147444A - Display systems

Info

Publication number: GB2147444A
Application number: GB08326212A
Authority: GB
Inventors: Brian Robert Beale
Original assignee: Racal Research Ltd
Current assignee: Racal Research Ltd
Priority date: 1983-09-30
Filing date: 1983-09-30
Publication date: 1985-05-09
Also published as: GB8326212D0

Abstract

A liquid crystal display system is described made up of a plurality of identical modules 4, 6, 8 and 10 which are arranged to interlock (vertically or horizontally, or both) in light-tight manner within a housing 18. Module 2 and 12 respectively provide power supply and microprocessor controls. Each module carries two multi-way electrical Connectors, and electrical connections to all the modules are completed by means of short multi- way connecting links. Each liquid crystal display is preferably transflective and uses a poorly reflective diffuser so that the display is predominantly produced by back- lighting in poor ambient light and predominantly produced by the reflected ambient light when the latter is good. This is found to produce a substantially constant- brightness display. Adjacent modules may additionally be held together by spring clips. <IMAGE>

Description

SPECIFICATION Display systems The invention relates to display systems and more specifically to display systems using liquid crystal displays.

Various features of the invention will be apparent from the following description, given by way of example only, of liquid crystal display ("LCD") systems embodying the invention, reference being made to the accompanying diagramatic drawings in which: Figure 1 is the front elevation of one of the display systems; Figure 2 is a front elevation of another one of the display systems; Figure 3 is an enlarged front elevation of part of one of the display systems of Figs. 1 and 2; Figure 4 is a cross-section on the line (III-III) of Fig. 1; and Figure 5 is a rear view, looking in the direction of the arrow V of Fig. 4.

More specifically to be described below is a liquid crystal display module, comprising a body portion presenting a front face defining a window through which the liquid crystal display is visible, the body portion supporting the liquid crystal display, drive circuitry therefor and electrical connecting means, and carrying interlock means by means of which it interlocks with an adjacent and identical module in a light-tight manner.

Advantageously, each module is rectangular in external configuration and its body portion presents a projection along each of two adjacent edges thereof and a recess along each of the other two adjacent edges thereof, the projections being sized and shaped so as to interlock in light-tight manner with the recesses of the adjacent module and the recesses being sized and shaped to interlock in light-tight manner with the projections of adjacent module.

Advantageously, the module is adapted to be back-lit and the window is defined by poorly reflective light diffuser means which is so adapted in relation to the back lighting that the display externally visible through the window is predominantly produced by light transmission though the diffuser means and the liquid crystal display from the back lighting in conditions of poor ambient light and is produced predominantly by ambient light reflected from the diffuser means through the liquid crystal display and the window in conditions of relatively bright ambient light.

Advantageously, the connector means of the module comprises two separate electrical connectors respectively positioned adjacent opposite edges of the module and so electrically connected with each other and with the liquid display and the driving circuitry therefor that the module may be electrically connected to adjacent modules on each of the two opposite sides by means of electrical connections from each of its connectors to the physically closest one of the connectors of the adjacent module.

In a more specific sense, there will be disclosed below a liquid crystal display ("LCD") system comprising a plurality of separate but interlocked identical modules, each of which defines a window and carries a liquid crystal display behind the window for providing a variable display visible through the window when appropriately lit, driving circuitry and electrical connector means.

Each module is advantageously rectangular.

Advantageously, it is interlocked with each adjacent module is substantially light-tight manner by means of linear projections interengaging with respective linear recesses, each projection running along the complete length of a respective module side and each recess running along the complete length of a respective module side.

Each module is preferably in the form of a shallow box whose base defines the said window, the liquid crystal display being carried on a plate which is held in position over the window by means of a light diffuser plate which is placed behind the liquid crystal display plate and at least partly held in position by one or more lips on the inside surface of one of the sides of the box. Advantageously, the outside surfaces of the box sides carry the said projections and recesses.

The driving circuitry may be carried on a printed circuit board which is fixed in position in the said box so as physically to at least partly hold the light diffuser plate in position.

Advantageously, the system includes a plurality of clips which clip sides of adjacent modules together.

There may also advantageously be provided a plurality of linear mounting strips each for running alongside a plurality of interlocked modules, each mounting strip having linear projection means for interlocking with the recesses of the modules and linear recesses for interlocking with the linear projections of the modules.

Advantageously, the mounting strips carry mechanical fastening means by means of which they and the interlocked modules may be physically mounted within an external housing or the like.

Advantageously, the housing or the like supports electric lighting means. The light diffuser plates of each module may be poorly reflective and so adapted in relation to the lighting means that the display externally visible through the window of each module is produced predominantly by light transmission through the light diffuser plate and the liquid crystal display in conditions of poor ambient light and is produced predominantly by ambient light reflected from the light diffuser plate through the liquid crystal display plate and the window in conditions of relatively bright ambient light.

The foregoing are exemplary and not exhaustive of the various novel features of the LCD systems now to be more specifically described.

Fig. 1 shows the front view of one of the LCD systems. This comprises a number of modules, six in this example, 2, 4, 6, 8, 10, 1 2. Each module is identical in external configuration, as will be described in more detail below. From the front, each module has a surround 14 and a "window" 16. In the display shown in Fig. 1, the modules 4, 6, 8 and 10 carry liquid crystal displays and each presents a display through its window 1 6.

The module 2 is a power supply module and the module 1 2 is a microprocessor control module and their "windows" 1 6 are in fact opaque. In this particular example, each LCD module 4, 6, 8 and 10 presents a display in the form of a matrix of thirty five LCD areas arranged in seven rows, each containing five displays as shown for the module 4 (but omitted from the modules 6, 8 and 10). Thus, by appropriately energising some or all of the thirty five individual LCD's in the matrix of each of the modules 4, 6, 8 and 10, that matrix can be arranged to display an appropriate symbol, for example an alpha-numeric symbol. Such display can of course be arranged to change automatically under control of the microprocessor module 1 2, in known fashion.The total display provided by all four modules 4, 6, 8 and 10 can thus be used for a variety of purposes, e.g. informational or advertising purposes.

Because each of the modules 4, 6, 8 and 10, as well as the power supply and microprocessor modules 2 and 12, is identical, the user can build up any desired format of display simply by assembling the required number of modules, in a manner to be explained, and electrically interconnecting them, again in a manner to be explained.

In the particular example in Fig. 1, the modules are arranged one on top of the other to provide a vertical type of display. However, instead they may by arranged horizontally, as shown in Fig. 2 in which items corresponding to those in Fig. 1 are correspondingly referenced. Thus, each module is designed (again as will be explained) to interlock with another similar module on each of its four sides.

Therefore, of course, displays may be built up from more than one adjacent columns of modules and from more than one adjacent rows of modules. As shown, the modules are mounted in a housing 18.

Fig. 3 shows the front view of one of the modules 2-12 to an enlarged scale. The module may be made of plastics for example and has a chamfered edge 20 and a chamfered profile 22 around the window 16. Also visible in Fig. 3 are linear projections 24 and 26 on two adjacent edges of the module.

Fig. 4 shows two of the modules of the display system of Fig. 1, one of the modules, module 10, being shown in cross-section and the adjacent, lower, module, module 12, being shown in side elevation.

Fig. 4 shows the plastics body 28 of each module, showing the module as having the form of a shallow rectangular box with four sides 28A, 28B, 28C and 28D, and a base 28E in which the window 1 6 is formed. As shown in Fig. 4, the upper (in this view) side 28A of each module defines a recess 30 running the width of module, and a similar recess, 32, runs along the vertical side 28D of each module opposite the side 28A carrying the linear projection 24 (see Fig. 3). Fig.

4 therefore shows how the modules interlock with each other. Thus, the projection 26 on side 28B of module 10 interlocks with the recess 30 of module 1 2. Similarly, the projection 26 on the module 8 interlocks in the recess 30 of module 1 0.

It will be apparent that, in a horizontal type of display system as shown in Fig. 2, each linear projection 24 (see Fig. 3), would interlock with the corresponding recess 32 of the adjacent module.

Adjacent modules are partly held together by spring clips 33. Each clip 34 is U-shaped and is snapped over the upper edge 28A of one of the two modules being joined together and over a shoulder 34 (see Fig. 5) on the lower edge 28B. In a horizontal type of display as shown in Fig. 2, spring clips 33 would hold adjacent sides of the modules together, each such clip engaging over the side 28D of one of the modules and over a recess 35 in the side 28C of the adjacent module.

In order to enable the interlocked modules to be mounted in the housing 18, mounting strips 36 (Fig. 4), are provided. The mounting strips may be made of extruded metal, for example, and run along the four sides of the total display. Each mounting strip has a recess 37 and two separate linear projections 38A and 38B. These are spaced apart by such distance that together they define a width corresponding to the width of each of the linear projections 24 and 26 on the sides of each module. Thus, the mounting strip 36 is mounted in the attitude shown in Fig. 4 when next to the side of a module carrying a projection 24 or 26, as shown in Fig. 4; however, when it runs adjacent to the side of a module having a recess 30 or 32, the mounting strip would be mounted in the reverse attitude so that the two projections 38A and 38B interlock with the recess in the module. Each mounting strip has a longitudinal slot 39 for receiving one leg of one of the mounting clips 33.

Finally, each strip 36 has a threaded bore for receiving a bolt 40 by means of which the assembled modules may be attached into the housing 18. It will be appreciated that the housing 18 takes any suitable form as required by the use to which the display system is to be put. If the display system is simply a portable sign, then the housing may be a simple box. However, the housing may of course be part of an existing structure to which the display is to be attached.

Fig. 4 shows the LCD itself at 41, being shown diagrammatically as a 'sandwich' of two plates. A rectangular light diffuser plate 42 is placed behind the LCD 41. The driving circuitry for the LCD is carried on a printed circuit board 44 which is rectangular in shape and held in position below the window 1 6 by screws 46 as shown in Fig. 5. Fig. 4 shows how the diffuser plate 42 is held in position along its lower edge by the printed circuit board 44 and along its upper edge by being clipped behind two shoulders 48 and 50. In turn, the diffuser plate hold the LCD 41 in position over the window 16. The LCD 41 and the diffuser plate 42 are not visible in Fig. 5. Electrical connections from the printed circuit board 44 to the LCD are made by flexible electrically conductive rubber connectors 54 (Fig. 4).

The printed circuit board also carries two seven-way electrical connectors 56 and 58 by means of which power supply and control signals are supplied to the LCD's.

The housing 1 8 carries a suitable light source indicated in this example as a linear light source 60.

The interlocking of the modules in the display system by means of interlocking projections and recesses running along the length of each side of the module is important because it ensures that the modules are linked together in a light-tight manner so that no light from the light source 60 can emerge between the modules.

The printed circuit board 44 includes electrical connections to the two connectors 56 and 58 which are so arranged that adjacent modules can be simply electrically connected to each other by means of short seven-way links, each connected from one of the connectors 56 or 58 to the closest connector on the adjacent module-as shown diagrammatically in Fig. 5. In other words, each printed circuit board includes power supply interconnections running between appropriate terminals on the connectors 56 and 58 of that module and correspondingly carries any common control connections (which are to be connected in parallel to all the modules). This means that electrical interconnection of the modules to each other (and to the power supply and the microprocessor modules 2 and 12) is simplified.There is no need for electrical connections to be made in parallel to all the connectors because this function is already performed by the connections in each printed circuit board. This also has the advantage that no connections pass, within each module, between connector 56 and connector 58 and there is therefore no risk of such connections inadvertently coming into view through the window 16.

The whole arrangement therefore provides greatly simplified mechanical assembly and electrical interconnection. A user can simply purchase the required number of modules (display modules and the power supply and microprocessor modules) and then mechanically interlock them in any desired manner in order to produce the required final display.

They can be easily held together and mounted within the user's own housing by means of the mounting strips 36. Finally, electrical interconnection is simplified in the manner expalined, it merely being necessary for him to link adjacent connectors 56, 58 with short interconnecting links.

Each liquid crystal display may be of any suitable form. Advantageously, however, each LCD is of the guest-host dichroic type. The display is arranged to be of the transflective type. Advantageously, the diffuser plate 42 in each module is arranged to be poorly reflective. The effect of this is that in conditions of relatively poor or normal ambient light, the visible display is produced mainly by the light from the back-lighting 60 by transmission through the diffuser plate 42. However, as the ambient light increases, for example from increasing sunlight, the display predominantly becomes produced by reflection of the ambient light from the diffuser plate 42 and back through the LCD 41 and the window 16. This arrangement is found to produce an overall display with substantially constant illumination even in sharply changing conditions of ambient light.

Claims

1. A liquid crystal display module, comprising a body portion presenting a front face defining a window through which the liquid crystal display is visible, the body portion supporting the liquid crystal display, drive circuitry therefor and electrical connecting means, and carrying interlock means by means of which it interlocks with an adjacent and identical module in a light-tight manner.

2. A module according to claim 1, in which each module is rectangular in external configuration and its body portion presents a projection along each of two adjacent edges thereof and a recess along each of the other two adjacent edges thereof, the projections being sized and shaped so as to interlock in light-tight manner with the recesses of the adjacent module and recesses being sized and shaped to interlock in light-tight manner with the projections of adjacent module.

3. A module according to claim 1 or 2, which is adapted to be back-lit and the window is defined by poorly reflective light diffuser means which is so adapted in relation to the back lighting that the display externally visible through the window is predominantly produced by light transmission though the diffuser means and the liquid crystal display from the back lighting in conditions of poor ambient light and is produced predominantly by ambient light reflected from the diffuser means through the liquid crystal display and the window in conditions of relatively bright ambient light.

4. A module according to any preceding claim, in which the connecting means comprises two separate electrical connectors respectively positioned adjacent opposite edges of the module and so electrically connected with each other and with the liquid display and the driving circuitry therefor that the module may be electrically connected to adjacent modules on each of the two opposite sides by means of electrical connections from each of its connectors to the physically closest one of the connectors of the adjacent module.

5. A liquid crystal display system, comprising a plurality of separate but interlocked identical modules, each of which defines a window and carries a liquid crystal display behind the window for providing a variable display visible through the window when appropriately lit, driving circuitry and electrical connector means.

6. A system according to claim 5, in which each module is rectangular.

7. A system according to claim 6, in which each module is interlocked with each adjacent module in substantially light-tight manner by means of linear projections interengaging with respective linear recesses, each projection running along the complete length of a respective module side and each recess running along the complete length of a respective module side.

8. A system according to claim 6 or 7, in which each module is in the form of a shallow box whose base defines the said window, the liquid crystal display being carried on a plate which is held in position over the window by means of a light diffuser plate which is placed behind the liquid crystal display plate and at least partly held in position by one or more lips on the inside surface of one of the sides of the box.

9. A system according to claim 8, in which the outside surfaces of the box sides carry the said projections and recesses.

10. A system according to claim 8 or 9, in which the driving circuitry is carried on a printed circuit board which is fixed in position in the said box so as physically to at least partly hold the light diffuser plate in position.

11. A system according to any one of claims 5 to 10, including a plurality of clips which clip sides of adjacent modules together.

1 2. A system according to any one of claims 5 to 11, including a plurality of linear mounting strips each for running alongside a plurality of interlocked modules, each mounting strip having linear projection means for interlocking with the recesses of the modules and linear recesses for interlocking with the linear projections of the modules.

1 3. A system according to claim 12, in which the mounting strips carry mechanical fastening means by means of which they and the interlocked modules may be physically mounted within an external housing or the like.

14. A system according to claim 13, in which the housing or the like supports electric lighting means.

1 5. A system according to claim 8 or to any one of claims 9 to 14 as dependent on claim 8, in which the light diffuser plates of each module are poorly reflective and so adapted in relation to the lighting means that the display externally visible through the window of each module is produced predominantly by light transmission through the light diffuser plate and the liquid crystal display in conditions of poor ambient light and is produced predominantly by ambient light reflected from the light diffuser plate through the liquid crystal display plate and the window in conditions of relatively bright ambient light.

16. A liquid crystal display module substantially as described with reference to the accompanying drawings.

1 7. A liquid crystal display system substantially as described with reference to the accompanying drawings.