CA1249890A - Display device controlled by a diode matrix network - Google Patents
Display device controlled by a diode matrix networkInfo
- Publication number
- CA1249890A CA1249890A CA000484171A CA484171A CA1249890A CA 1249890 A CA1249890 A CA 1249890A CA 000484171 A CA000484171 A CA 000484171A CA 484171 A CA484171 A CA 484171A CA 1249890 A CA1249890 A CA 1249890A
- Authority
- CA
- Canada
- Prior art keywords
- diode
- diodes
- display
- display apparatus
- pair
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09F—DISPLAYING; ADVERTISING; SIGNS; LABELS OR NAME-PLATES; SEALS
- G09F9/00—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements
- G09F9/30—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements in which the desired character or characters are formed by combining individual elements
- G09F9/37—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements in which the desired character or characters are formed by combining individual elements being movable elements
- G09F9/375—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements in which the desired character or characters are formed by combining individual elements being movable elements the position of the elements being controlled by the application of a magnetic field
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Theoretical Computer Science (AREA)
- Control Of Indicators Other Than Cathode Ray Tubes (AREA)
- Control Of El Displays (AREA)
- Devices For Indicating Variable Information By Combining Individual Elements (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE:
The invention relates to a display device comprising electrically controlled display elements which are selectively energised by a diode matrix network. The technical problem to be solved is to avoid extensive mal-function due to short-circuiting of a single control diode.
In accordance with the invention, each diode for supplying control current in respective directions to a given display element is backed up by a respective second diode connected in series with and in the same direction as the first diode.
During maintenance operation, the matrix network is energised with a test voltage sufficiently low for the display elements not to be actuated, the test voltage being several times higher than the forward potential drop across one diode. The invention is especially applicable to display panels placed along motorways.
The invention relates to a display device comprising electrically controlled display elements which are selectively energised by a diode matrix network. The technical problem to be solved is to avoid extensive mal-function due to short-circuiting of a single control diode.
In accordance with the invention, each diode for supplying control current in respective directions to a given display element is backed up by a respective second diode connected in series with and in the same direction as the first diode.
During maintenance operation, the matrix network is energised with a test voltage sufficiently low for the display elements not to be actuated, the test voltage being several times higher than the forward potential drop across one diode. The invention is especially applicable to display panels placed along motorways.
Description
9~) DISPLAY DEVICE CONTROLLED BY A DIODE ~ATRIX NETWORK
Background of the invention The present invention relates to display devices comprising electrically controlled display elements which are energised selectively by means of a diode matrix network ; the unitary display elements may for example comprise flaps mounted to pivot between a display position and a retracted position, their pivoting being controlled by a relay, which is preferably a double_acting relay ;
these display elements may also consist of luminous devices.
The invention is more particularly applicable to display panels or devices which are disposed in places where access is difficult or in places which are only accessible during short or infrequent periods. This is the case in particular for the indicator panels used on motor-ways and especially on high density traffic urban motor-ways or roads for which an interruption of traffic for purposes of maintenance risks causing problems and must therefore be limite~ in dura~n and frequency.
Description of the Prior Art In a display device having electro-mechanical display elements of known design, each relay controlling the tilting of a flap is actuated in both directions to move the flap to its display position and to return it to its retracted position by means of a diode matrix network comprising a respective diode connected to each relay for each direction of the control current. The failures which can affect each display element are of two kinds :
- in the first kind, the electrical connection is interrupted , for example by the breakage of a wire of a coil or when a control diode open-circuits; such a failure only affects the defective display element and the message displayed remains legible.
i2~9~90 - on the other hand, when one of the two control diodes of a display element short-circuits, the derivative currents from the short-circuit diode may create a pertur-bation over a large part of the display panel, whose message may become illegible.
Objects of the invention An object of the invention is to provide a dis-play device of the kind referred to above in which a failure concerning one display element does not cause perturbation in the rest of the display device and, more particularly, in which a short-circuit in a control diode does not create parasitic currents on other display .elements.
Description of the invention According to the present invention, there is provided an electromechanical display apparatus comprising discrete movable display elements which can adopt two po-sitions, and several relays by which each of said elementscan be individually activated, said relays being energized in a selective manner by means of a diode matrix network, each relay being energized by a pair of diodes, each diode of a pair of diodes having one contact connected to one contact of its respective relay, the two diodes of one pair of diodes being connected in an opposite conductive direction, each diode of a pair of diodes hav:ing its second contact connected to an actuat:ing e:Lectri.ca:l. suppLy :L:ine, display apparatus where.irl an additional diode is connected in series with each diode of said pairs oE diodes in the same conductive direction; and for maintenance purpose, each discrete display element is energized with a prede-termined voltage which does not activa-te said discrete display elements, said predetermined voltage being e~ual . . .
- 2a -to at least s~e times the forward poten-tial drop across one diode.
The presence of the second control diodes in series with the first diode prevents a short-circuit failure in one diode producing parasitic currents in a control circuit of other display elements; such parasitic currents will only appear in the unlikely event of simultaneous short-circuits in both diodes of a same control circuit.
Moreover, since test voltages are insufficient to actuate the display elements, a test operation may /
9o be performed without displaying erroneous or illegible messages on the array during maintenance.
When one diode short-circuits, the potential drop across it becomes very small, and the current flowing in the control circuit under a potential difference which is somewhat higher than the sum of the normal forward potential drops across the series connection of the diodes is increased by an amount which is suf-ficiently large to be dete~ted readily by measurement of the current flowing.
In a preferred embodiment of the invention, test means operable in automatic mode during periods of non-utilisation of said array are provided, said test means including means for recording the test results.
This enables the number of repair operations on the display array and matrix network to be reduced, since it is sufficient to replace the components of a display element recorded as defective.
Advantageously, said test means comprises micrO-prOcessOr means, for detecting short-circuit diodes, said micro-processor means also controlling the selective actuation of said supply means.
Preferably, the apparatus includes a plurality of said arrays and of said matrix networks, a central station, and telecommunication means for transmitting the test results from said matrix networks to said central station. The defective display arrays and net-works being known in advance, it is sufficient to inter-vene on the failed devices only, which iurther reduccs the interventionsneceC~sary Description of the drawings Other features and advantages of the invention will appear from the following description, given by way of example, with reference to the accompanying drawings in which :
- Fig. 1 is a schematic electric diagram of part of a display device of known design ;
;~249~0 - Fig. 2 is a similar schematic diagram showing a display device in accordance with the present invention.
Description of the Preferred embodiment Fig. 1 is a diagram of part of the electrical circuit of a prior art display device having electromechanical display elements such as hinged flaps (not shown) which can adopt two positions : a first display position in which they are visible on the display board, and a second rest position in which they are retracted and invisible on the display board.
The movement of the display flaps is actuated in each direction, towards the display position and towards the retracted posi-tion, by means of a coil 1 supplied by a diode matrix network so as to enable current to pass in one direction or the other between first and second terminals of the coil.
The network comprises "column" conductors shown vertically in the drawing, to each of which are connected one of the terminals of the coils 1 of a respec-tiie column,and ~line" conductors 3 and 4 shown horizontally in the drawing r the line conductors 3 are each connec-ted to the second terminals of the coils of a respective line through a first control diode 5, each of the diodes 5 being connected to the conductor 3 by the same electrode (for example the anode, as in the example shown).
Similarly, each of the conductors 4 is connected to the second terminal of the coils 1 of a respective line through a diode 6 connected the opposite way from the diodes 5, that is to say with its anode connected to the coil in the example shown.
The actuation of a display element to move it to its retracted position or to its display position is obtained by applying a suitable voltage between the con-ductor 2 of the relevant column and the conductor 3 or 4 of the relevant line for the element considered.
When a diode 5 short-circuits, derivative currents are c~ed and part of the display device malfunctions so that the displayed message may beco~e incomprehensible.
-- 4 _ In accordance with the embodiment of the present invention, as shown in Fig. 2, which is a similar diagram to Fig. 1, a second diode is connected in series with each of the control diodes, the two diodes in series ha~ing the same forward conductive direction.
Thus, each actuation of the display element, that is to say each movement of the display flap in the embodiment shown, is controlled by means of the pair of diodes in series, that is to say the diodes 5 and 5' for one movement, and diodes 6 and 6' for the opposite movement.
Because the drop in potential across the diodes in the forward direction is small relative to the supply potential for the coils, the in~roduction of a second diode in series has a negligeable influence on the normal ope-ration of the display device. Thus, for a supply potential of 30 ~ , giving a control current of 3A, the reduction of control current is only 2 %. However, in order to detect a short-circuit diode, the network may be energised at a potential which is sufficiently low that the display elements are not actuated, but which is at least as high as several times the forward potential drop across one diode, so t~at the increase in current produced by the short-circuit of a diode is sufficiently large in relative value to be measured and detected readily. For example , in the case indicated above, if the 3~Y supply potential is replaced by a 5V potential, which is 7 times the forward potential drop across a diode, the increase in current resulting from the short-circuit of one diode and from the consequent elimination of the forwarcl potential drop across this diode is of the order of 20 % which is readi-ly detected.
Advantageously, the operation of detecting short-circuit diodes is performed while the display device or board is inoperative ; this operation can be performed automatically by means of a control device testing all the display devices in succession, the result of these 12~
tests being recorded so that when access to the display device is obtainable, it will only be necessary to replace the display elements detected as defective.
In the case of control of the display device by a micro-processor integrated into the display device, the operation of detecting short-circuit diodes may be per-formed by this micro-processor.
It is also possible for a certain number of display devices to form part of a group controlled by a central station to which they are connected by a telecommu-nication system ; this is the case for example in the case of a series of display panels along a motorway or express road, In this case, the result of the operations of detecting short-circuit diodes is adva~tageous~y transmitted to the central station so as to know in advance which display panels have defective elements, which avoids intervening on display devices which have no defective elements ; this further reduces malntenance times.
Background of the invention The present invention relates to display devices comprising electrically controlled display elements which are energised selectively by means of a diode matrix network ; the unitary display elements may for example comprise flaps mounted to pivot between a display position and a retracted position, their pivoting being controlled by a relay, which is preferably a double_acting relay ;
these display elements may also consist of luminous devices.
The invention is more particularly applicable to display panels or devices which are disposed in places where access is difficult or in places which are only accessible during short or infrequent periods. This is the case in particular for the indicator panels used on motor-ways and especially on high density traffic urban motor-ways or roads for which an interruption of traffic for purposes of maintenance risks causing problems and must therefore be limite~ in dura~n and frequency.
Description of the Prior Art In a display device having electro-mechanical display elements of known design, each relay controlling the tilting of a flap is actuated in both directions to move the flap to its display position and to return it to its retracted position by means of a diode matrix network comprising a respective diode connected to each relay for each direction of the control current. The failures which can affect each display element are of two kinds :
- in the first kind, the electrical connection is interrupted , for example by the breakage of a wire of a coil or when a control diode open-circuits; such a failure only affects the defective display element and the message displayed remains legible.
i2~9~90 - on the other hand, when one of the two control diodes of a display element short-circuits, the derivative currents from the short-circuit diode may create a pertur-bation over a large part of the display panel, whose message may become illegible.
Objects of the invention An object of the invention is to provide a dis-play device of the kind referred to above in which a failure concerning one display element does not cause perturbation in the rest of the display device and, more particularly, in which a short-circuit in a control diode does not create parasitic currents on other display .elements.
Description of the invention According to the present invention, there is provided an electromechanical display apparatus comprising discrete movable display elements which can adopt two po-sitions, and several relays by which each of said elementscan be individually activated, said relays being energized in a selective manner by means of a diode matrix network, each relay being energized by a pair of diodes, each diode of a pair of diodes having one contact connected to one contact of its respective relay, the two diodes of one pair of diodes being connected in an opposite conductive direction, each diode of a pair of diodes hav:ing its second contact connected to an actuat:ing e:Lectri.ca:l. suppLy :L:ine, display apparatus where.irl an additional diode is connected in series with each diode of said pairs oE diodes in the same conductive direction; and for maintenance purpose, each discrete display element is energized with a prede-termined voltage which does not activa-te said discrete display elements, said predetermined voltage being e~ual . . .
- 2a -to at least s~e times the forward poten-tial drop across one diode.
The presence of the second control diodes in series with the first diode prevents a short-circuit failure in one diode producing parasitic currents in a control circuit of other display elements; such parasitic currents will only appear in the unlikely event of simultaneous short-circuits in both diodes of a same control circuit.
Moreover, since test voltages are insufficient to actuate the display elements, a test operation may /
9o be performed without displaying erroneous or illegible messages on the array during maintenance.
When one diode short-circuits, the potential drop across it becomes very small, and the current flowing in the control circuit under a potential difference which is somewhat higher than the sum of the normal forward potential drops across the series connection of the diodes is increased by an amount which is suf-ficiently large to be dete~ted readily by measurement of the current flowing.
In a preferred embodiment of the invention, test means operable in automatic mode during periods of non-utilisation of said array are provided, said test means including means for recording the test results.
This enables the number of repair operations on the display array and matrix network to be reduced, since it is sufficient to replace the components of a display element recorded as defective.
Advantageously, said test means comprises micrO-prOcessOr means, for detecting short-circuit diodes, said micro-processor means also controlling the selective actuation of said supply means.
Preferably, the apparatus includes a plurality of said arrays and of said matrix networks, a central station, and telecommunication means for transmitting the test results from said matrix networks to said central station. The defective display arrays and net-works being known in advance, it is sufficient to inter-vene on the failed devices only, which iurther reduccs the interventionsneceC~sary Description of the drawings Other features and advantages of the invention will appear from the following description, given by way of example, with reference to the accompanying drawings in which :
- Fig. 1 is a schematic electric diagram of part of a display device of known design ;
;~249~0 - Fig. 2 is a similar schematic diagram showing a display device in accordance with the present invention.
Description of the Preferred embodiment Fig. 1 is a diagram of part of the electrical circuit of a prior art display device having electromechanical display elements such as hinged flaps (not shown) which can adopt two positions : a first display position in which they are visible on the display board, and a second rest position in which they are retracted and invisible on the display board.
The movement of the display flaps is actuated in each direction, towards the display position and towards the retracted posi-tion, by means of a coil 1 supplied by a diode matrix network so as to enable current to pass in one direction or the other between first and second terminals of the coil.
The network comprises "column" conductors shown vertically in the drawing, to each of which are connected one of the terminals of the coils 1 of a respec-tiie column,and ~line" conductors 3 and 4 shown horizontally in the drawing r the line conductors 3 are each connec-ted to the second terminals of the coils of a respective line through a first control diode 5, each of the diodes 5 being connected to the conductor 3 by the same electrode (for example the anode, as in the example shown).
Similarly, each of the conductors 4 is connected to the second terminal of the coils 1 of a respective line through a diode 6 connected the opposite way from the diodes 5, that is to say with its anode connected to the coil in the example shown.
The actuation of a display element to move it to its retracted position or to its display position is obtained by applying a suitable voltage between the con-ductor 2 of the relevant column and the conductor 3 or 4 of the relevant line for the element considered.
When a diode 5 short-circuits, derivative currents are c~ed and part of the display device malfunctions so that the displayed message may beco~e incomprehensible.
-- 4 _ In accordance with the embodiment of the present invention, as shown in Fig. 2, which is a similar diagram to Fig. 1, a second diode is connected in series with each of the control diodes, the two diodes in series ha~ing the same forward conductive direction.
Thus, each actuation of the display element, that is to say each movement of the display flap in the embodiment shown, is controlled by means of the pair of diodes in series, that is to say the diodes 5 and 5' for one movement, and diodes 6 and 6' for the opposite movement.
Because the drop in potential across the diodes in the forward direction is small relative to the supply potential for the coils, the in~roduction of a second diode in series has a negligeable influence on the normal ope-ration of the display device. Thus, for a supply potential of 30 ~ , giving a control current of 3A, the reduction of control current is only 2 %. However, in order to detect a short-circuit diode, the network may be energised at a potential which is sufficiently low that the display elements are not actuated, but which is at least as high as several times the forward potential drop across one diode, so t~at the increase in current produced by the short-circuit of a diode is sufficiently large in relative value to be measured and detected readily. For example , in the case indicated above, if the 3~Y supply potential is replaced by a 5V potential, which is 7 times the forward potential drop across a diode, the increase in current resulting from the short-circuit of one diode and from the consequent elimination of the forwarcl potential drop across this diode is of the order of 20 % which is readi-ly detected.
Advantageously, the operation of detecting short-circuit diodes is performed while the display device or board is inoperative ; this operation can be performed automatically by means of a control device testing all the display devices in succession, the result of these 12~
tests being recorded so that when access to the display device is obtainable, it will only be necessary to replace the display elements detected as defective.
In the case of control of the display device by a micro-processor integrated into the display device, the operation of detecting short-circuit diodes may be per-formed by this micro-processor.
It is also possible for a certain number of display devices to form part of a group controlled by a central station to which they are connected by a telecommu-nication system ; this is the case for example in the case of a series of display panels along a motorway or express road, In this case, the result of the operations of detecting short-circuit diodes is adva~tageous~y transmitted to the central station so as to know in advance which display panels have defective elements, which avoids intervening on display devices which have no defective elements ; this further reduces malntenance times.
Claims (4)
1. Electromechanical display apparatus comprising discrete movable display elements which can adopt two po-sitions, and several relays by which each of said elements can be individually activated, said relays being energized in a selective manner by means of a diode matrix network, each relay being energized by a pair of diodes, each diode of a pair of diodes having one contact connected to one contact of its respective relay, the two diodes of one pair of diodes being connected in an opposite conductive direction, each diode of a pair of diodes having its second contact connected to an actuating electrical supply line, display apparatus wherein an additional diode is connected in series with each diode of said pairs of diodes in the same conductive direction; and for maintenance purpose, each discrete display element is energized with a prede-termined voltage which does not activate said discrete display elements, said predetermined voltage being equal to at least some times the forward potential drop across one diode.
2. Display apparatus as claimed in claim 1, fur-ther comprising a test means operable in automatic mode during periods of non-utilisation of said display elements, said test means including means for recording test results.
3. Display apparatus as claimed in claim 2, wherein said test means comprises micro-processor means for detecting short-circuit diodes, said micro-processor means also controlling the selective actuation of said supply lines.
4. Display apparatus as claimed in claim 2 or 3, including a plurality of said display elements, and of said matrix network, a central station, and tele-communication means for transmitting the test results from said matrix networks to said central station.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR8409978A FR2566565B1 (en) | 1984-06-25 | 1984-06-25 | DISPLAY DEVICE COMPRISING ELECTRICALLY CONTROLLED UNIT ELEMENTS CONTROLLED BY A DIODE MATRIX NETWORK |
| FR8409978 | 1984-06-25 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1249890A true CA1249890A (en) | 1989-02-07 |
Family
ID=9305394
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000484171A Expired CA1249890A (en) | 1984-06-25 | 1985-06-17 | Display device controlled by a diode matrix network |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0167445B1 (en) |
| AT (1) | ATE39193T1 (en) |
| CA (1) | CA1249890A (en) |
| DE (1) | DE3566744D1 (en) |
| FR (1) | FR2566565B1 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0438614A1 (en) * | 1990-01-23 | 1991-07-31 | Alternative Energy Research Center Inc. | Information display apparatus and method |
| DE4024499C1 (en) * | 1990-08-02 | 1991-09-26 | Dambach-Werke Gmbh, 7560 Gaggenau, De |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CH516204A (en) * | 1970-01-21 | 1971-11-30 | Fok Gyem Finommech Elekt | Device for the visual transmission of information, in particular for providing information to travelers |
| FR2517999B1 (en) * | 1981-12-15 | 1985-06-21 | Peugeot Outillage Elect | MULTI-SPEED PORTABLE DRILL |
-
1984
- 1984-06-25 FR FR8409978A patent/FR2566565B1/en not_active Expired
-
1985
- 1985-06-17 CA CA000484171A patent/CA1249890A/en not_active Expired
- 1985-06-24 AT AT85401258T patent/ATE39193T1/en active
- 1985-06-24 EP EP85401258A patent/EP0167445B1/en not_active Expired
- 1985-06-24 DE DE8585401258T patent/DE3566744D1/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| EP0167445A1 (en) | 1986-01-08 |
| DE3566744D1 (en) | 1989-01-12 |
| EP0167445B1 (en) | 1988-12-07 |
| ATE39193T1 (en) | 1988-12-15 |
| FR2566565B1 (en) | 1986-11-28 |
| FR2566565A1 (en) | 1985-12-27 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |