CA1103451A - Information display devices - Google Patents
Information display devicesInfo
- Publication number
- CA1103451A CA1103451A CA323,928A CA323928A CA1103451A CA 1103451 A CA1103451 A CA 1103451A CA 323928 A CA323928 A CA 323928A CA 1103451 A CA1103451 A CA 1103451A
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- Prior art keywords
- light
- area
- vane
- observer
- display device
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Abstract
ABSTRACT
There is provided an electrically controlled information display device having a two-dimensional planar array of display elements in horizontal and vertical rows. Each such element can be set to a first station which it displays a light emissive area and a light reflective area, and a second state in which these areas are replaced by a corresponding area of low reflectance.
The display may thus be viewed either by transmitted or by reflect-ed light. The light emissive area of each element is a light trans-missive area in an otherwise opaque member, and each display element includes a vane with a highly reflective face constituting the reflective area, and another face of low reflectance. The vane can be pivoted about a hinge axis adjacent to the light transmissive area between a first position in which the vane covers the light transmissive area exposing its low reflectance area to an observer, and a second position in which the vane uncovers the light trans-missive area and exposed its highly reflective face to the observer.
me vane is movable by magnet means between its two positions.
There is provided an electrically controlled information display device having a two-dimensional planar array of display elements in horizontal and vertical rows. Each such element can be set to a first station which it displays a light emissive area and a light reflective area, and a second state in which these areas are replaced by a corresponding area of low reflectance.
The display may thus be viewed either by transmitted or by reflect-ed light. The light emissive area of each element is a light trans-missive area in an otherwise opaque member, and each display element includes a vane with a highly reflective face constituting the reflective area, and another face of low reflectance. The vane can be pivoted about a hinge axis adjacent to the light transmissive area between a first position in which the vane covers the light transmissive area exposing its low reflectance area to an observer, and a second position in which the vane uncovers the light trans-missive area and exposed its highly reflective face to the observer.
me vane is movable by magnet means between its two positions.
Description
sackground of the Invention Field of the Invention This invention relates to matrix display devices, that is to display dev~ces co~prisin~ a large plurality of elements arranged adjacently and each individually con-trollable to display different aspects to an observer.
Description of the Prior Art There are known in the art from United Kingdom Patent Specifications No. 355,440 and 934,001 electrically controlled dot matrix display devices in which each dot element includes a laminar member, having differently ; reflective opposed faces, arranged to be rotatable about an axis parallel to the plane of the array so as to build up characters out of selections of reflective dots.
For night viewing it is necessary to illuminate the prior art displays from in front by light sources requiring to be relatively remote from the display device.
The appearance at night compares unfavourably with matrix displays of the type in which each element is a tungsten light source.
Summary of the Invention It is an object of an aspect of the invention to provide a matrix display device which reduces or obviates disadvantages of the known art.
It is an object of an aspect of the invention to provide a matrix display device providing an improved appearance both in daylight and in night-time operation.
It is an object of an aspect of the invention to enable the number of actuators required to set the display to a desired condition to be reduced.
In accordance with one aspect of this invention there is provided an electrically controlled information displ~y device including a two-dimensional planar array of display elements arranged in horizontal and vertical rows, characterized in that:
each said display element is selectively sett-able to a first state in which there are simultaneously displayed to the obser~er t~o adjacent areas of which one is a light-emissive area arranged to emit light to~ards the observer and the other is a reflective ~_ . ~ 3 area arranged to reflect light to the observer and to a second state in which each said area is replaced by a - correspondiny area of low reflectance;
~. the light-emissive area of each said display element is :~ 5 a light-transmissive area in an ot~erwise opaque member disposed between a light source and the observerî
each said display element includes a vane ha~ing a ::` reflective face constituting said reflective area and an opposing face of lower reflectance constituting a said area :~ 10 of low reflectance;
each said vane is arranged for pivotal movement about a hinge axis adjacent t~ a~d to one edge of the respective said light-transmissive area between a first position in which said vane covers said light-transmissive area and exposes its lower reflectance surface to the observer and a second position in which said vane uncovers said light~transmissive area and exposes its reflective face to the observer;
said vane comprises a permanent magnet arranged for cooperation with a respective one of a plurality of electro-magnets included in an electromagnet assembly arranged formovement with respect to said array so that each said electromagnet is successively disposed for coop~ration with each of a predetermined plurality of said permanent magnets to produce selective movement of the respective said vane ~etween one and the other o~ saicl first and second positions, stabilizing means are provided whereby each said vane is stable in each of said first and second positions;
said light source is common to a plurality of said display elements.
In accordance with another aspect of this invention there is provided an electrically controlled matrix informa-tion display device including a two-dimensional array,of display elements arranged in horizontal and vertical rows, characterized in that each said element is settable to a first state in which it simultaneously displays to an obserYer two adjacent areas of which one is a light emissive area arranged to emit light ~rds said observer and the other is a reflective area arranged to re~lect light towards the observer, and a second state in which each said area is 7 ~, 3,;~i' L~i~3~
: 3a : replaced by a corresponding area of low re~lectance, whereby said display element may ~e viewed ~ot~ ~y transmitted light and by re~lected l~ht;
the light emissive area o~ each said display element :5 is a light-transmissive area in an otherwise opaque member :arranged between a light source common to a plurality of said display elements and the o~server;
: each said display element includes a vane having a -`~ reflective face constituting said reflective area and another face of lower reflectance constituting said area of low reflectance;
said vane is arranged for pivotal movement about a hinge axis adjacent to and to one edge of said light transmissive area between a first position in which said vane covers said light transmissive area and exposes its : lower-reflectance face to the observer and a second position : in which said vane uncovers said light transmissive area and . exposes its reflective face to the o~server, said vane comprises ~ permanent magnet; and ~: 20 magnet means are arranged to cooperate with said permanent magnet for selectively producing movement of said vane between one and the other of said first and second positions.
The present invention has the advantage of allowing 25 .back lighting of the device, yie].ding a high-contrast display at night having an appearance that compares favourably with light bulb matrix displays and may be of any chosen colour and enabling the light :
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, sources to be placed within the device cabinet and thus better protected from the weather. Not only does the invention enhance the appearance of the display but it also enables the number of display element actuators to be reduced in a simple manner. These two advantages allow a lo~ cost internally illuminated display to be provided, ~hich has the characteristic of being clearly readable in daytime when the internal lighting o~ the device is switched off.
The daytime appearance can, if desired, be enhanced by keeping the back lighting on. Such enhance-ment is particularly striking on o~ercast or foggy days.
Brief Description of the Drawings Figure 1 is a perspective view of a portion of a display device in accordance with the invention;
Figures 2 arld 3 show sectional ele~ations through one element of a display device in accordance with the invention in its alternate operating conditions;
Figure 4 and 5 show to a reduced scale front elevations of the element of Fi,gures 2 and 3 in its alternate conditions of operation;
Figure 6A is a sectional view of one element of a display device in accordance with another embodiment of the invention, in one operating condition;
Figure 6B is a sectional view of the element of Figure 6A, in its other operating condition, and Figure 7 is a schematic perspective illustration of a preferred embodiment of electromagnet for use in the invention.
Figure 8 is a front elevation of a portion of a modified display device;
Figures 9 and 10 illustrate a 7-se~nent display device embodying the invention;
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Figure 11 shows to an enlarged scale a portion of the device of Figures 9 and 10, and ~igures 12 and 13 illustrate a modified embodi-ment vf di~play device embodying the inventio~.
Figures 1 - 5 illustrate a display device 10 ;~ comprising an opaque sheet member 11 pie~ced by a matrix of equispaced rectangular apertures 12, each having an associated shutter 13. Each shutter 13 is pivotally - mounted for movement abo~t a horizontal pivot axis 14 ~o as either to occult or to expose the respective aperture 12~ The side of each shutter 13 that is exposed to ~iew when the associated aperture is occulted is made non-reflective, conveniently matt black, as is the major portion of the front surface 15 of sheet member 11. The other side~-~f each shutter member 13, that is exposed to view when the shutter is pivoted downwards to expose the ;~ respective aperture 12, is made reflective. It may conveniently be painted white, or otherwise coated with a reflective material 13a, as is a ~agnet 24 which is affixed to this surface of the shutter and co-operates with an electromagnet to actuate the shutter between its open and closed positions as described in relation to ~igures 2 and 3. When shutter 13 is opened it is supported at an acute angle to sheet 11 by a projection 18 extending forwardly from sheet 11, and conveniently formed integrally therewith. Brackets 16 e~tend from sheet 11 at each end of every shutter member to provide the required pivotal support for the shutters.
The shutters advantageously have a lateral width W slightly in excess of the width w of the apertures and a height H which slightly exceeds the height h of the apertures. Thus a s-trip 17 of the front surface 15 of shee-t 11 bordering each aperture abo~e and at each side is covered when the respectiYe shutter is raised and exposed when the shutter is lowered. This -, :,, ' ~ ' L
marginal strip can be ntade reflective to match ths shutter surface that is simultaneously exposed to view.
~ ovement of each shutter member between its raised (closed) and lowered (open) positions is effected by electromagnetic means, ~o~veniently using a vertical array of electromagnets 20, one electromagnet for each row of apertures in the matrix. As shown in Figure 1, the electromagnet~ 20 may be carried on a vertical support member 40 arranged by known means (not shown) for reciprocating movement in a horizontal direction (as indicated by arrows 41), with each of ma~nets 20 traversing a respective horizontal row of sh~tters 13 to co-operate with each in turn, a~ required. The electromagnets 20 are arranged to be energized select-ively in either polarity, in such a manner that thedirection of energization may be selected in respect of each shutter member as the magnet is caused to traver~e the array. As shown in ~igure 2, the winding 21 of each ele~tromagnet is connectable to a source 22 of direct current by way of a switch 23 operable to cause current to pass through the windin~ in either directionO In practice, switch 23 will most conveniently be a semi-conductor swi*chins arrangement arranged to be actuated synchronously with the movement of the magnet array past ; 25 the shutters.
On each shutter 13 is fastened a permanent magnet 24 ha~ing opposed poles respectively adja~ent the hinge axis and remote therefrom. The magnet polarity is the same for all the shutters and for the sake of convenience it will be assumed that, as denoted by reference~ N and S, the north pole is remote from and the south pole adjacent to the hinge axis. If electro-magnet 20, when positioned in the same vertical plane a~
the shutter magnet ~s shown in Fig~re 5, is now energized to produce a north pole at its top and a south pole at .
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its bottom and the shutter member is closed, as shown in Fi$ure 2, then the shutter magnet 24 will be repelled and rotated and the shutter 13 will be caused to pivot to its open position, as shown in Fi~ure 3. If, with the shutter in this open position, magnet 20 is energi~ed so as to produce a south pole at its top and a north pole at its bottom, then magnet 24 will again be ` repelled and rotated, and shutter 13 will be caused to pivot to its closed position.
When shutter 13 is open as shown in ~igurs 3 light from a source 30 of light (Figure 1) positioned behind the sheet 11 may pass through the aperture 12 ~ unobstructsd by the shutter, as indicatsd by a~row 31, ; while light incident on the reflsctive exposed face 13a of the shutter from a source 32 ~ill also be visible to an observer as indicated by arrows 33. I~hen in its open position it will be seen that the shutter is held inclined to the vertical at an acute angle by the presence of support 18, since this increases the amount of light reflscted towards ths viewer from the source 32 abovs the shutter, which source may for example, be day light or light from roof lighting. A sheet of light diffusing translucent material is advantageously placed behind or within ths apsrture 1~, since this i~provss ~ 25 the daytime appearance by reflecting some of the ambient ; light incident on the front of the device, ~rhen the shutter is open. It also provides diffusion of the back -~ light passing through the aperture during night-time operation, thus assisting viewing of the display from positions other than directly in front of it.
The display elements described above are ravitationally bistable, but alternatively or additionally the elements may be made magnetically bistable by providing soft-iron pins 37, 38 each of which ~ttracts the magnet 24 in a respective one of its ~table position~ ?
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pin 37, which extends partly across the aperture 12 from a vertica~ edge thereof9 when the shutter is closed and pin 38t which is conveniently located within projection 18, when the shutter is open.
The shutter menlber 13 should ideally be very thin, so as to reduce its mass as far as possible and - thus increase the speed of operation~ The shutter and permanent magnet may be made as an integral unit, for example by forming the shutter by an injection moulding proces~ from a material that is permanently magnetisable.
Figures 6A and 6B illustrate an alternative -~ construction of shutter element, in which permanent magnet 24 of Figures 2 - 5 is replaced by a cylindrical magnet 25 mounted concsntrically with shutter pi~ot axis 14 and magnetized transversely to the axis, so that the porti~n on one side of a diameter 26 represents a north magnetic pole and the portion on the other side of this diameter represents a south pole. The electro-magnet 20' in this case is in the form of a rod or bar having its axis at right angles to the plane of the array. When it is desired to open the shutter frorn the ~ closed position shown in Figure 6A the winding 21' of ;~ electromagnet 20' is energised so as to produce adjacent magnet 25 a like p~le to that presented by magnet 25, in th~ illu~trated case, a north pole. It will be noted that the diameter 26 dividing the north and sout-h pol~r regions of magnet 25 is inclined to the vertical~ so that the field of this magnet is asymmetrically presented to electromagnet 20' in such a manner that the inter-action of the fields of magnet 25 and electromagnet 20'produces on the m~gnet a torque tending to rotate the shutter clockwise as shown in the drawing. Xn $he closed position of the shutter light 31 from a source disposed behind the shutter array will be obstructed by the closed shutter. With the shutter open, as shown in Figure 6B, .. . . .
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, ' light from a source behind the shutter array will pass through aperture 12 as indicated at 31, while light from an overhead source will be reflected by the reflective inner face of the shutter as indicated at 33. ~rom the open position of Figure 6B the shutter is returned to its closed position by energi~ing electrom~gnet 20' so that its end nearest magnet 25 becomes a south pole. It will be seen that because the position o~ shutter 13 in ` its open position is limited by projection 11a, the magnet 25 is again in such a position with respeot to electromagnet 20' that a torque in ths required direction, in this case anticlockwise, is produced.
Above a certain speed of travel of the electro-magnets 20' there may be a tendency for the actuated shutters to bounce back, particularly when the shutters are being closed. To prevent this bounce it is possible to use a moving electromagnet assembly in which the pole of each electromagnet is flanked by soft-iron members, as shown in Figure 7. Here an electromagnet 20' with its winding 21' presents an end face 20'a towards a shutter array (not shown). Two soft-iron members 27, 28 are arranged with their faces 27a, 28a co-planar with face 20'a and symmetrically with respect to electro-magnet 20'. This arrangement en~ures that when a shutter member is returned to its closed position, as shown in ~'igur~ 6A~ the shutt~r magnet 25 will interact with member 27 or 28, according to the direction of movement (indicated by arrow 41), to retain the shutter in i*~
closed position and restrain shutter bounce.
It will be understood that the array of electro-magnets 20 or 20' carried on a common support member 40 is arranged to move with respect to the shutter array so thst in its limiti~g positions it is not aligned with the endmost vertical row of shutters, but leaves them free for the pa~sage of light therethrough. In a _ 9 _ modificRtion which is not thought to require illustration, a horizontally aligned set of electromagnets is arranged to move vertically over the array. This alternative ~- arrangemsnt produces a more rapid change of display in solne instances.
A modification of the display device described above may be used to provide displays in different colours, as will now be described with reference to Figure 8. In this Figure each of a group of four adjacent display elements is arranged to display a different colour, when actuated~ In the Figure, all the elements are shown as actuated together~ which is not the only mode of operation of a selected group. In other modes three, two or one of the elements of each selected group will be actuated. The display will ;~ comprise a large plurality of groups, and when viewed from a sufficiently large distance each group will appear as a ~ingle dot having a colour dependent on the combination of elements selected within it.
The group of elements illustrated comprises four apertures 12, which are individually provided wi*h differently coloured diffuser elements 35b, 35r, 35 and 35w, which may be assumed to pass preferentially light of the colours blue, red, yellow and white, res-pectively. The apertures are closed by respective shutters 13, which have their reflecti~e surface~ coated with materials 13b, 13r, 13y, 13w selectively reflective to the corresponding colours~
In daytime use, colour is provided by the ambient lighting reflected by the coloured ~hutter surfaces of the selected display elements, while for night~time operation the coloured reflection of ambient lighting may be supplemented by coloured light pa~sing through the coloured diffusers of the open aper*ures.
35 Obviously~ sets of colours other than four ' ` ` -- 10 ':
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may be controlled in the general manner disclosed above.
Figures 9 and 10 illustrate respectively the appearance in high and low ambient light conditions of a 7-segment display device embodying the invention. In each Figure, all of the display segments are shown as actuated to the ~mark" position~ so that a numeral "~"
is displayed. In Figure 9 there are shown the seven reflective shutter surfaces 41-47, each flanking a dis-persive translucent surface 51-57, and all visible against a dark surface 15 of the opaque sheet 11.
Figure 11 shows in some detail the construction of a part of the display device of Figures 9 and 10.
An opaque sheet 11 is pierced by aperture~ 12 having : 15 the required forms and locations for the elements of the display. Each aperture 12 is controlled by a res-pectiYe shutter 13 operated by a respective hidden reversibly energisable electromagnet 61, 62, 6~, co-operating with a permanent magnet 24 of the associated shutte~. The magnetic axis of magnet 24 is normal to - the plane of the shutter. SurfGIce 15 of sheet 11 is of low reflectance, conveniently black7 while surfaces 41, 42, ~4 of the shutters, exposed when they are positioned so as not to occult the respective apertures 12, are highly reflective. Apertures 12 are preferably filled hy dispersive elements 51, 52, 54 to eliminate ~ glare from lamp~ 72 which are disposed behind opaque ; sheet 11.
Figures 12 and 13 illustrate an embodiment in which particularly high efficiency of illumination is obtained. Opaque masking members 70 of arcuate section, each pierced by apertures 71, are interposed between an observer and respective vertically disposed lumine-scent tube~ 72 disposed within the recess of the ma~k.
Each aperture 71 has an associated matingly curved ' ' , .
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shutter member 73 pivoted to mask member 70 for movement about a vertical hinge axis 74 adJacent an edge of the respective aperture 71 so as to be movable between a first or closed position, in which the res-pective aperture is covered and the shutter memberdisplays a low-reflectance convex surface 73a to the observer, and a second or open position in which the shutter displays a concave and reflective surface 73b to the observer. Behind each lamp 72 is disposed a concave reflector 75 from which, when the sllutter iY
open, some light from lamp 72 is reflected through aperture 71. Rsflector 75 is formed by a reflective coating upon a member 76 of concavely arcuate section which extends laterally beyond masking member 70 to form extensions 76a. Other light from the lamp also passes directly through the aperture when the shutter is open, ~ to pass directly to the observer or to be reflected : towards the observer from conca~e shutter surface 73b.
hen in its open position, shutter 73 l.ies against res-pective extension 76a of the member 76. Those surfaces : 76b of extensions 76a of member 76 which are visible to the observer when shutters 73 are closed are arranged to be of low reflectance~
Each shutter 73 comprises a permanent magnet 77 which co-operates with a reversible energisable electromagnet 78 (Figure 13) to provide movement of the shutter between its open and closed positions~ An electromagnet 78 may be provided for each shutter or a single electromagnet may be arranged to be traversed vertically along each column of shutter~ to actuate each in turn~ Stability of shutters 73 in their open and closed positions may conveniently be provided by soft-iron members 79, oO positioned for co-operation with the shutter permanent magnet 77. The electro~
magnet assembly is so arranged that when passing a group . ~
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of display elements that are in said first state and that are required to remain in that same state *he electromagnet assembly does not obstruct the passage ; of light that affects the appearance of said group of display elements.
A light-diffuser 81 (shown only in Figure 13) may be positioned within mask member 70 to reduce glare~
~; or this may be replaced by a member providing sets of - colour filters whereby the opening of adjacent shutters ~ 10 displays light of different colours to *he obser~er. ~s -~ in other embodiments, the light may be coloured red, blue or green or remain as unfiltered "white" light.
The reflective surface 73b of the shu*ter of each aper-ture ca~ be painted the same colour as the filter of ~-` 15 the aperture.
`~ The arrangement in ~igure 12 i5 ~clearly read-able in daylight with lamps 72 switched off, because of the reflectance of surface 73b of the shutter, and the reflectance of surface 75 and of the lamp 72, which may be a fluorescent lamp. The appearance wh~n viewed by daylight can be enhanced by turning on the lamps. ~ :
; It is an adYantage of the invention that inactive areas of the display, that i9, those areas of which the appearance is unchanged by actuation of -~ any dlsplay element, may be reduced to insignificant ~- proportions, and it is an advantage of the embodiment - in Figures 12 and 13 that when each of the display elements is in the brighter of its two states almost the whole area occupied by the array reflects ambient light and radiates light deri~ed from said light source.
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Description of the Prior Art There are known in the art from United Kingdom Patent Specifications No. 355,440 and 934,001 electrically controlled dot matrix display devices in which each dot element includes a laminar member, having differently ; reflective opposed faces, arranged to be rotatable about an axis parallel to the plane of the array so as to build up characters out of selections of reflective dots.
For night viewing it is necessary to illuminate the prior art displays from in front by light sources requiring to be relatively remote from the display device.
The appearance at night compares unfavourably with matrix displays of the type in which each element is a tungsten light source.
Summary of the Invention It is an object of an aspect of the invention to provide a matrix display device which reduces or obviates disadvantages of the known art.
It is an object of an aspect of the invention to provide a matrix display device providing an improved appearance both in daylight and in night-time operation.
It is an object of an aspect of the invention to enable the number of actuators required to set the display to a desired condition to be reduced.
In accordance with one aspect of this invention there is provided an electrically controlled information displ~y device including a two-dimensional planar array of display elements arranged in horizontal and vertical rows, characterized in that:
each said display element is selectively sett-able to a first state in which there are simultaneously displayed to the obser~er t~o adjacent areas of which one is a light-emissive area arranged to emit light to~ards the observer and the other is a reflective ~_ . ~ 3 area arranged to reflect light to the observer and to a second state in which each said area is replaced by a - correspondiny area of low reflectance;
~. the light-emissive area of each said display element is :~ 5 a light-transmissive area in an ot~erwise opaque member disposed between a light source and the observerî
each said display element includes a vane ha~ing a ::` reflective face constituting said reflective area and an opposing face of lower reflectance constituting a said area :~ 10 of low reflectance;
each said vane is arranged for pivotal movement about a hinge axis adjacent t~ a~d to one edge of the respective said light-transmissive area between a first position in which said vane covers said light-transmissive area and exposes its lower reflectance surface to the observer and a second position in which said vane uncovers said light~transmissive area and exposes its reflective face to the observer;
said vane comprises a permanent magnet arranged for cooperation with a respective one of a plurality of electro-magnets included in an electromagnet assembly arranged formovement with respect to said array so that each said electromagnet is successively disposed for coop~ration with each of a predetermined plurality of said permanent magnets to produce selective movement of the respective said vane ~etween one and the other o~ saicl first and second positions, stabilizing means are provided whereby each said vane is stable in each of said first and second positions;
said light source is common to a plurality of said display elements.
In accordance with another aspect of this invention there is provided an electrically controlled matrix informa-tion display device including a two-dimensional array,of display elements arranged in horizontal and vertical rows, characterized in that each said element is settable to a first state in which it simultaneously displays to an obserYer two adjacent areas of which one is a light emissive area arranged to emit light ~rds said observer and the other is a reflective area arranged to re~lect light towards the observer, and a second state in which each said area is 7 ~, 3,;~i' L~i~3~
: 3a : replaced by a corresponding area of low re~lectance, whereby said display element may ~e viewed ~ot~ ~y transmitted light and by re~lected l~ht;
the light emissive area o~ each said display element :5 is a light-transmissive area in an otherwise opaque member :arranged between a light source common to a plurality of said display elements and the o~server;
: each said display element includes a vane having a -`~ reflective face constituting said reflective area and another face of lower reflectance constituting said area of low reflectance;
said vane is arranged for pivotal movement about a hinge axis adjacent to and to one edge of said light transmissive area between a first position in which said vane covers said light transmissive area and exposes its : lower-reflectance face to the observer and a second position : in which said vane uncovers said light transmissive area and . exposes its reflective face to the o~server, said vane comprises ~ permanent magnet; and ~: 20 magnet means are arranged to cooperate with said permanent magnet for selectively producing movement of said vane between one and the other of said first and second positions.
The present invention has the advantage of allowing 25 .back lighting of the device, yie].ding a high-contrast display at night having an appearance that compares favourably with light bulb matrix displays and may be of any chosen colour and enabling the light :
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, sources to be placed within the device cabinet and thus better protected from the weather. Not only does the invention enhance the appearance of the display but it also enables the number of display element actuators to be reduced in a simple manner. These two advantages allow a lo~ cost internally illuminated display to be provided, ~hich has the characteristic of being clearly readable in daytime when the internal lighting o~ the device is switched off.
The daytime appearance can, if desired, be enhanced by keeping the back lighting on. Such enhance-ment is particularly striking on o~ercast or foggy days.
Brief Description of the Drawings Figure 1 is a perspective view of a portion of a display device in accordance with the invention;
Figures 2 arld 3 show sectional ele~ations through one element of a display device in accordance with the invention in its alternate operating conditions;
Figure 4 and 5 show to a reduced scale front elevations of the element of Fi,gures 2 and 3 in its alternate conditions of operation;
Figure 6A is a sectional view of one element of a display device in accordance with another embodiment of the invention, in one operating condition;
Figure 6B is a sectional view of the element of Figure 6A, in its other operating condition, and Figure 7 is a schematic perspective illustration of a preferred embodiment of electromagnet for use in the invention.
Figure 8 is a front elevation of a portion of a modified display device;
Figures 9 and 10 illustrate a 7-se~nent display device embodying the invention;
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Figure 11 shows to an enlarged scale a portion of the device of Figures 9 and 10, and ~igures 12 and 13 illustrate a modified embodi-ment vf di~play device embodying the inventio~.
Figures 1 - 5 illustrate a display device 10 ;~ comprising an opaque sheet member 11 pie~ced by a matrix of equispaced rectangular apertures 12, each having an associated shutter 13. Each shutter 13 is pivotally - mounted for movement abo~t a horizontal pivot axis 14 ~o as either to occult or to expose the respective aperture 12~ The side of each shutter 13 that is exposed to ~iew when the associated aperture is occulted is made non-reflective, conveniently matt black, as is the major portion of the front surface 15 of sheet member 11. The other side~-~f each shutter member 13, that is exposed to view when the shutter is pivoted downwards to expose the ;~ respective aperture 12, is made reflective. It may conveniently be painted white, or otherwise coated with a reflective material 13a, as is a ~agnet 24 which is affixed to this surface of the shutter and co-operates with an electromagnet to actuate the shutter between its open and closed positions as described in relation to ~igures 2 and 3. When shutter 13 is opened it is supported at an acute angle to sheet 11 by a projection 18 extending forwardly from sheet 11, and conveniently formed integrally therewith. Brackets 16 e~tend from sheet 11 at each end of every shutter member to provide the required pivotal support for the shutters.
The shutters advantageously have a lateral width W slightly in excess of the width w of the apertures and a height H which slightly exceeds the height h of the apertures. Thus a s-trip 17 of the front surface 15 of shee-t 11 bordering each aperture abo~e and at each side is covered when the respectiYe shutter is raised and exposed when the shutter is lowered. This -, :,, ' ~ ' L
marginal strip can be ntade reflective to match ths shutter surface that is simultaneously exposed to view.
~ ovement of each shutter member between its raised (closed) and lowered (open) positions is effected by electromagnetic means, ~o~veniently using a vertical array of electromagnets 20, one electromagnet for each row of apertures in the matrix. As shown in Figure 1, the electromagnet~ 20 may be carried on a vertical support member 40 arranged by known means (not shown) for reciprocating movement in a horizontal direction (as indicated by arrows 41), with each of ma~nets 20 traversing a respective horizontal row of sh~tters 13 to co-operate with each in turn, a~ required. The electromagnets 20 are arranged to be energized select-ively in either polarity, in such a manner that thedirection of energization may be selected in respect of each shutter member as the magnet is caused to traver~e the array. As shown in ~igure 2, the winding 21 of each ele~tromagnet is connectable to a source 22 of direct current by way of a switch 23 operable to cause current to pass through the windin~ in either directionO In practice, switch 23 will most conveniently be a semi-conductor swi*chins arrangement arranged to be actuated synchronously with the movement of the magnet array past ; 25 the shutters.
On each shutter 13 is fastened a permanent magnet 24 ha~ing opposed poles respectively adja~ent the hinge axis and remote therefrom. The magnet polarity is the same for all the shutters and for the sake of convenience it will be assumed that, as denoted by reference~ N and S, the north pole is remote from and the south pole adjacent to the hinge axis. If electro-magnet 20, when positioned in the same vertical plane a~
the shutter magnet ~s shown in Fig~re 5, is now energized to produce a north pole at its top and a south pole at .
: ~
~;~3~
its bottom and the shutter member is closed, as shown in Fi$ure 2, then the shutter magnet 24 will be repelled and rotated and the shutter 13 will be caused to pivot to its open position, as shown in Fi~ure 3. If, with the shutter in this open position, magnet 20 is energi~ed so as to produce a south pole at its top and a north pole at its bottom, then magnet 24 will again be ` repelled and rotated, and shutter 13 will be caused to pivot to its closed position.
When shutter 13 is open as shown in ~igurs 3 light from a source 30 of light (Figure 1) positioned behind the sheet 11 may pass through the aperture 12 ~ unobstructsd by the shutter, as indicatsd by a~row 31, ; while light incident on the reflsctive exposed face 13a of the shutter from a source 32 ~ill also be visible to an observer as indicated by arrows 33. I~hen in its open position it will be seen that the shutter is held inclined to the vertical at an acute angle by the presence of support 18, since this increases the amount of light reflscted towards ths viewer from the source 32 abovs the shutter, which source may for example, be day light or light from roof lighting. A sheet of light diffusing translucent material is advantageously placed behind or within ths apsrture 1~, since this i~provss ~ 25 the daytime appearance by reflecting some of the ambient ; light incident on the front of the device, ~rhen the shutter is open. It also provides diffusion of the back -~ light passing through the aperture during night-time operation, thus assisting viewing of the display from positions other than directly in front of it.
The display elements described above are ravitationally bistable, but alternatively or additionally the elements may be made magnetically bistable by providing soft-iron pins 37, 38 each of which ~ttracts the magnet 24 in a respective one of its ~table position~ ?
, . ' , 3~
pin 37, which extends partly across the aperture 12 from a vertica~ edge thereof9 when the shutter is closed and pin 38t which is conveniently located within projection 18, when the shutter is open.
The shutter menlber 13 should ideally be very thin, so as to reduce its mass as far as possible and - thus increase the speed of operation~ The shutter and permanent magnet may be made as an integral unit, for example by forming the shutter by an injection moulding proces~ from a material that is permanently magnetisable.
Figures 6A and 6B illustrate an alternative -~ construction of shutter element, in which permanent magnet 24 of Figures 2 - 5 is replaced by a cylindrical magnet 25 mounted concsntrically with shutter pi~ot axis 14 and magnetized transversely to the axis, so that the porti~n on one side of a diameter 26 represents a north magnetic pole and the portion on the other side of this diameter represents a south pole. The electro-magnet 20' in this case is in the form of a rod or bar having its axis at right angles to the plane of the array. When it is desired to open the shutter frorn the ~ closed position shown in Figure 6A the winding 21' of ;~ electromagnet 20' is energised so as to produce adjacent magnet 25 a like p~le to that presented by magnet 25, in th~ illu~trated case, a north pole. It will be noted that the diameter 26 dividing the north and sout-h pol~r regions of magnet 25 is inclined to the vertical~ so that the field of this magnet is asymmetrically presented to electromagnet 20' in such a manner that the inter-action of the fields of magnet 25 and electromagnet 20'produces on the m~gnet a torque tending to rotate the shutter clockwise as shown in the drawing. Xn $he closed position of the shutter light 31 from a source disposed behind the shutter array will be obstructed by the closed shutter. With the shutter open, as shown in Figure 6B, .. . . .
,': '' : ' ' :
..
, ' light from a source behind the shutter array will pass through aperture 12 as indicated at 31, while light from an overhead source will be reflected by the reflective inner face of the shutter as indicated at 33. ~rom the open position of Figure 6B the shutter is returned to its closed position by energi~ing electrom~gnet 20' so that its end nearest magnet 25 becomes a south pole. It will be seen that because the position o~ shutter 13 in ` its open position is limited by projection 11a, the magnet 25 is again in such a position with respeot to electromagnet 20' that a torque in ths required direction, in this case anticlockwise, is produced.
Above a certain speed of travel of the electro-magnets 20' there may be a tendency for the actuated shutters to bounce back, particularly when the shutters are being closed. To prevent this bounce it is possible to use a moving electromagnet assembly in which the pole of each electromagnet is flanked by soft-iron members, as shown in Figure 7. Here an electromagnet 20' with its winding 21' presents an end face 20'a towards a shutter array (not shown). Two soft-iron members 27, 28 are arranged with their faces 27a, 28a co-planar with face 20'a and symmetrically with respect to electro-magnet 20'. This arrangement en~ures that when a shutter member is returned to its closed position, as shown in ~'igur~ 6A~ the shutt~r magnet 25 will interact with member 27 or 28, according to the direction of movement (indicated by arrow 41), to retain the shutter in i*~
closed position and restrain shutter bounce.
It will be understood that the array of electro-magnets 20 or 20' carried on a common support member 40 is arranged to move with respect to the shutter array so thst in its limiti~g positions it is not aligned with the endmost vertical row of shutters, but leaves them free for the pa~sage of light therethrough. In a _ 9 _ modificRtion which is not thought to require illustration, a horizontally aligned set of electromagnets is arranged to move vertically over the array. This alternative ~- arrangemsnt produces a more rapid change of display in solne instances.
A modification of the display device described above may be used to provide displays in different colours, as will now be described with reference to Figure 8. In this Figure each of a group of four adjacent display elements is arranged to display a different colour, when actuated~ In the Figure, all the elements are shown as actuated together~ which is not the only mode of operation of a selected group. In other modes three, two or one of the elements of each selected group will be actuated. The display will ;~ comprise a large plurality of groups, and when viewed from a sufficiently large distance each group will appear as a ~ingle dot having a colour dependent on the combination of elements selected within it.
The group of elements illustrated comprises four apertures 12, which are individually provided wi*h differently coloured diffuser elements 35b, 35r, 35 and 35w, which may be assumed to pass preferentially light of the colours blue, red, yellow and white, res-pectively. The apertures are closed by respective shutters 13, which have their reflecti~e surface~ coated with materials 13b, 13r, 13y, 13w selectively reflective to the corresponding colours~
In daytime use, colour is provided by the ambient lighting reflected by the coloured ~hutter surfaces of the selected display elements, while for night~time operation the coloured reflection of ambient lighting may be supplemented by coloured light pa~sing through the coloured diffusers of the open aper*ures.
35 Obviously~ sets of colours other than four ' ` ` -- 10 ':
, ~ " .:
,, 3~
`' :
, . .
may be controlled in the general manner disclosed above.
Figures 9 and 10 illustrate respectively the appearance in high and low ambient light conditions of a 7-segment display device embodying the invention. In each Figure, all of the display segments are shown as actuated to the ~mark" position~ so that a numeral "~"
is displayed. In Figure 9 there are shown the seven reflective shutter surfaces 41-47, each flanking a dis-persive translucent surface 51-57, and all visible against a dark surface 15 of the opaque sheet 11.
Figure 11 shows in some detail the construction of a part of the display device of Figures 9 and 10.
An opaque sheet 11 is pierced by aperture~ 12 having : 15 the required forms and locations for the elements of the display. Each aperture 12 is controlled by a res-pectiYe shutter 13 operated by a respective hidden reversibly energisable electromagnet 61, 62, 6~, co-operating with a permanent magnet 24 of the associated shutte~. The magnetic axis of magnet 24 is normal to - the plane of the shutter. SurfGIce 15 of sheet 11 is of low reflectance, conveniently black7 while surfaces 41, 42, ~4 of the shutters, exposed when they are positioned so as not to occult the respective apertures 12, are highly reflective. Apertures 12 are preferably filled hy dispersive elements 51, 52, 54 to eliminate ~ glare from lamp~ 72 which are disposed behind opaque ; sheet 11.
Figures 12 and 13 illustrate an embodiment in which particularly high efficiency of illumination is obtained. Opaque masking members 70 of arcuate section, each pierced by apertures 71, are interposed between an observer and respective vertically disposed lumine-scent tube~ 72 disposed within the recess of the ma~k.
Each aperture 71 has an associated matingly curved ' ' , .
.
.
.,:
shutter member 73 pivoted to mask member 70 for movement about a vertical hinge axis 74 adJacent an edge of the respective aperture 71 so as to be movable between a first or closed position, in which the res-pective aperture is covered and the shutter memberdisplays a low-reflectance convex surface 73a to the observer, and a second or open position in which the shutter displays a concave and reflective surface 73b to the observer. Behind each lamp 72 is disposed a concave reflector 75 from which, when the sllutter iY
open, some light from lamp 72 is reflected through aperture 71. Rsflector 75 is formed by a reflective coating upon a member 76 of concavely arcuate section which extends laterally beyond masking member 70 to form extensions 76a. Other light from the lamp also passes directly through the aperture when the shutter is open, ~ to pass directly to the observer or to be reflected : towards the observer from conca~e shutter surface 73b.
hen in its open position, shutter 73 l.ies against res-pective extension 76a of the member 76. Those surfaces : 76b of extensions 76a of member 76 which are visible to the observer when shutters 73 are closed are arranged to be of low reflectance~
Each shutter 73 comprises a permanent magnet 77 which co-operates with a reversible energisable electromagnet 78 (Figure 13) to provide movement of the shutter between its open and closed positions~ An electromagnet 78 may be provided for each shutter or a single electromagnet may be arranged to be traversed vertically along each column of shutter~ to actuate each in turn~ Stability of shutters 73 in their open and closed positions may conveniently be provided by soft-iron members 79, oO positioned for co-operation with the shutter permanent magnet 77. The electro~
magnet assembly is so arranged that when passing a group . ~
.
of display elements that are in said first state and that are required to remain in that same state *he electromagnet assembly does not obstruct the passage ; of light that affects the appearance of said group of display elements.
A light-diffuser 81 (shown only in Figure 13) may be positioned within mask member 70 to reduce glare~
~; or this may be replaced by a member providing sets of - colour filters whereby the opening of adjacent shutters ~ 10 displays light of different colours to *he obser~er. ~s -~ in other embodiments, the light may be coloured red, blue or green or remain as unfiltered "white" light.
The reflective surface 73b of the shu*ter of each aper-ture ca~ be painted the same colour as the filter of ~-` 15 the aperture.
`~ The arrangement in ~igure 12 i5 ~clearly read-able in daylight with lamps 72 switched off, because of the reflectance of surface 73b of the shutter, and the reflectance of surface 75 and of the lamp 72, which may be a fluorescent lamp. The appearance wh~n viewed by daylight can be enhanced by turning on the lamps. ~ :
; It is an adYantage of the invention that inactive areas of the display, that i9, those areas of which the appearance is unchanged by actuation of -~ any dlsplay element, may be reduced to insignificant ~- proportions, and it is an advantage of the embodiment - in Figures 12 and 13 that when each of the display elements is in the brighter of its two states almost the whole area occupied by the array reflects ambient light and radiates light deri~ed from said light source.
:,' - 13 _
Claims (15)
1. An electrically controlled information display device including a two-dimensional planar array of display elements arranged in horizontal and vertical rows, char-acterized in that:
each said display element is selectively settable to a first state in which there are simultaneously displayed to the observer two adjacent areas of which one is a light-emissive area arranged to emit light towards the observer and the other is a reflective area arranged to reflect light to the observer and to a second state in which each said area is replaced by a corresponding area of low reflectance;
the light-emissive area of each said display element is a light-transmissive area in an otherwise opaque member disposed between a light source and the observer;
each said display element includes a vane having a reflective face constituting said reflective area and an opposing face of lower reflectance constituting a said area of low reflectance;
each said vane is arranged for pivotal movement about a hinge axis adjacent to and to one edge of the respective said light-transmissive area between a first position in which said vane covers said light-transmissive area and exposes its lower reflectance surface to the observer and a second position in which said vane uncovers said light transmissive area and exposes its reflective face to the observer;
each said vane comprises a permanent magnet arranged for co-operation with a respective one of a plur-ality of electromagnets included in an electromagnet assembly arranged for movement with respect to said array so that each said electromagnet is successively disposed for co-operation with each of a predetermined plurality of said permanent magnets to produce selective movement of the respective said vane between one and the other of said first and second positions;
stabilising means are provided whereby each said vane is stable in each of said first and second positions;
said light source is common to a plurality of said display elements.
each said display element is selectively settable to a first state in which there are simultaneously displayed to the observer two adjacent areas of which one is a light-emissive area arranged to emit light towards the observer and the other is a reflective area arranged to reflect light to the observer and to a second state in which each said area is replaced by a corresponding area of low reflectance;
the light-emissive area of each said display element is a light-transmissive area in an otherwise opaque member disposed between a light source and the observer;
each said display element includes a vane having a reflective face constituting said reflective area and an opposing face of lower reflectance constituting a said area of low reflectance;
each said vane is arranged for pivotal movement about a hinge axis adjacent to and to one edge of the respective said light-transmissive area between a first position in which said vane covers said light-transmissive area and exposes its lower reflectance surface to the observer and a second position in which said vane uncovers said light transmissive area and exposes its reflective face to the observer;
each said vane comprises a permanent magnet arranged for co-operation with a respective one of a plur-ality of electromagnets included in an electromagnet assembly arranged for movement with respect to said array so that each said electromagnet is successively disposed for co-operation with each of a predetermined plurality of said permanent magnets to produce selective movement of the respective said vane between one and the other of said first and second positions;
stabilising means are provided whereby each said vane is stable in each of said first and second positions;
said light source is common to a plurality of said display elements.
2. The electrically controlled information display device claimed in claim l wherein said electromagnet assembly is so arranged that when passing a group of display elements that are in said first state and that are required to remain in that same state the electromagnet assembly does not obstruct the passage of light that affects the appear-ance of said group of display elements.
3. The electrically controlled information display device claimed in claim l wherein when each of said display elements is in said first state substantially the whole area occupied by the array reflects ambient light and radiates light derived from said light source.
4. The electrically controlled information display device claimed in claim 1 wherein said stabilising means comprises two soft-iron members disposed respectively to co-operate with a respective said permanent magnet to retain the respective vane in said first and in said second positions respectively.
5. The electrically controlled information display device claimed in claim l wherein each said vane is pivoted for movement about said hinge axis between said first and second positions such that the vane is gravitationally stable in each said position.
6. The electrically controlled information display device claimed in claim l wherein each electromagnet is flanked by a soft-iron member co-operating with said permanent magnets to reduce bounce of said vanes when actuated.
7. The electrically controlled information display device claimed in claim 1 and including a plurality of sets of light transmissive areas and vanes, each light transmissive area in each of said sets having associated therewith an optical filter selectively passing light of a colour different from the light passed by the other filters in the set, and the vane associated with each said light transmissive area having a reflective surface selectively reflecting light of the colour preferentially passed by the filter associated with the corresponding light transmissive area.
8. The electrically controlled information display device claimed in claim 1 wherein each said light trans-missive area comprises a light diffuser.
9. An electrically controlled matrix information display device including a two-dimensional array of display elements arranged in horizontal and vertical rows, char-acterized in that each said element is settable to a first state in which it simultaneously displays to an observer two adjacent areas of which one is a light emissive area arranged to emit light towards said observer and the other is a reflective area arranged to reflect light towards the observer, and a second state in which each said area is replaced by a corresponding area of low reflectance, whereby said display element may be viewed both by trans-mitted light and by reflected light;
The light emissive area of each said display element is a light-transmissive area in an otherwise opaque member arranged between a light source common to a plur-ality of said display elements and the observer;
each said display element includes a vane having a reflective face constituting said reflective area and another face of lower reflectance constituting said area of low reflectance;
said vane is arranged for pivotal movement about a hinge axis adjacent to and to one edge of said light transmissive area between a first position in which said vane covers said light transmissive area and exposes its lower-reflectance face to the observer and a second position in which said vane uncovers said light transmissive area and exposes its reflective face to the observer;
said vane comprises a permanent magnet; and magnet means are arranged to co-operate with said permanent magnet for selectively producing movement of said vane between one and the other of said first and second positions.
The light emissive area of each said display element is a light-transmissive area in an otherwise opaque member arranged between a light source common to a plur-ality of said display elements and the observer;
each said display element includes a vane having a reflective face constituting said reflective area and another face of lower reflectance constituting said area of low reflectance;
said vane is arranged for pivotal movement about a hinge axis adjacent to and to one edge of said light transmissive area between a first position in which said vane covers said light transmissive area and exposes its lower-reflectance face to the observer and a second position in which said vane uncovers said light transmissive area and exposes its reflective face to the observer;
said vane comprises a permanent magnet; and magnet means are arranged to co-operate with said permanent magnet for selectively producing movement of said vane between one and the other of said first and second positions.
10. The electrically controlled information display device claimed in claim 9 wherein said magnet means is disposed so that light can pass from said light source through said light-transmissive areas unobstructed by said magnet means.
11. The electrically controlled information display device claimed in claim 9 wherein when each of said display elements is in said first state substantially the whole area occupied by the array reflects ambient light and radiates light derived from said light source.
12. The electrically controlled information display device claimed in claim 9 and including a plurality of sets of light transmissive area and vanes, each light transmissive area in each of said sets having associated therewith an optical filter selectively passing light of a colour different from the light passed by the other filters in the set, and the vane associated with each said light transmissive area having a reflective surface selectively reflecting light of the colour preferentially passed by the filter associated with the corresponding light transmissive area.
13. The electrically controlled information display device claimed in claim 9 wherein each said light-transmissive area comprises a light diffuser.
14. A display device in accordance with claim 1 wherein each of said display elements includes a rectangular vane having a length substantially greater than its width and at least one set of said elements is arranged to form a seven-segment display pattern whereby representations of decimal digits may be displayed to the observer.
15. A display device in accordance with claim 9 wherein each of said display elements includes a rectangular vane having a length substantially greater than its width and at least one set of said elements is arranged to form a seven-segment display pattern whereby representations of decimal digits may be displayed to the observer.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA323,928A CA1103451A (en) | 1979-03-21 | 1979-03-21 | Information display devices |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA323,928A CA1103451A (en) | 1979-03-21 | 1979-03-21 | Information display devices |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1103451A true CA1103451A (en) | 1981-06-23 |
Family
ID=4113799
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA323,928A Expired CA1103451A (en) | 1979-03-21 | 1979-03-21 | Information display devices |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1103451A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5111193A (en) * | 1990-06-06 | 1992-05-05 | American On-Premise Advertising Company | Electronic display element for electronic display device |
| US5148156A (en) * | 1990-06-06 | 1992-09-15 | American Electronic Sign Company | Electronic display device having a plurality of pixel elements |
| US6677922B1 (en) | 1995-12-04 | 2004-01-13 | 3M Innovative Properties Company | Display element having retroreflective surface |
-
1979
- 1979-03-21 CA CA323,928A patent/CA1103451A/en not_active Expired
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5111193A (en) * | 1990-06-06 | 1992-05-05 | American On-Premise Advertising Company | Electronic display element for electronic display device |
| US5148156A (en) * | 1990-06-06 | 1992-09-15 | American Electronic Sign Company | Electronic display device having a plurality of pixel elements |
| US6677922B1 (en) | 1995-12-04 | 2004-01-13 | 3M Innovative Properties Company | Display element having retroreflective surface |
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| MKEX | Expiry |