CA1215793A - Indicating apparatus for elevatable and extendible structures - Google Patents
Indicating apparatus for elevatable and extendible structuresInfo
- Publication number
- CA1215793A CA1215793A CA000434127A CA434127A CA1215793A CA 1215793 A CA1215793 A CA 1215793A CA 000434127 A CA000434127 A CA 000434127A CA 434127 A CA434127 A CA 434127A CA 1215793 A CA1215793 A CA 1215793A
- Authority
- CA
- Canada
- Prior art keywords
- display
- display means
- ladder
- disposition
- elevation
- 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
- 239000004973 liquid crystal related substance Substances 0.000 claims abstract description 6
- 230000007246 mechanism Effects 0.000 claims description 4
- 230000000007 visual effect Effects 0.000 claims description 3
- 230000000903 blocking effect Effects 0.000 claims 1
- 239000004020 conductor Substances 0.000 description 5
- 230000000694 effects Effects 0.000 description 2
- 238000004040 coloring Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
Landscapes
- Ladders (AREA)
Abstract
A B S T R A C T
INDICATING APPARATUS FOR ELEVATABLE AND EXTENDIBLE
STRUCTURES
Apparatus for displaying the disposition (length and angle of elevation) of a structure, such as a turn-table fire escape ladder, uses a display means with radially arranged rows of display elements which are energised to model the actual disposition of the structure. Coloured sections on the display means overlying the elements indicate the safe mode of usage of the structure. Other parts of the display means are used to indicate when the actual angle of elevation of the structure lies outside a safe range. Analogue signals derived from the structure are converted to quantised digital form for operating the display means which is preferably liquid crystal but may be of light emitting diodes or a vacuum fluorescent device.
INDICATING APPARATUS FOR ELEVATABLE AND EXTENDIBLE
STRUCTURES
Apparatus for displaying the disposition (length and angle of elevation) of a structure, such as a turn-table fire escape ladder, uses a display means with radially arranged rows of display elements which are energised to model the actual disposition of the structure. Coloured sections on the display means overlying the elements indicate the safe mode of usage of the structure. Other parts of the display means are used to indicate when the actual angle of elevation of the structure lies outside a safe range. Analogue signals derived from the structure are converted to quantised digital form for operating the display means which is preferably liquid crystal but may be of light emitting diodes or a vacuum fluorescent device.
Description
7~3 INDICATING APPARATUS FOR ];`LEVATABL:E AND EXTENDIBLE STRUCTURES
This invention relates to indicating apparatus for - elevatable and extendible structures and is particularly but not exclusively suited to providing an indication of the position of an extendible ladder on a turntable.
In the use of a turntable it is particularly important that certain safety conditions be observed, under certain circumstances, for example on uneven ground at night,the precise angle of elevation of the ladder may not be so easy to judge and it may be possible for the use to depart from the safe limits. Usually the ladder is designed to operate with one man, two men or two men and a cage and safe limits of elevation and extension in conjunction with the different loads will be defined.
Hitherto, th~re has been provided a display in the form of an analogue scale with the cursor moved in direct relationship to the extension of the ladder together with an analogue or digital meter ind.~cating its elevation. The difficulty with such a display is that the operator must mentally relate the elevation angle indicated on the meter with the extension indicated on the extension scale to decide whether the operation is within the safe limits or not. In another for~ of display, a mechanically operated model ladder is shown against a bac}cground or overlay of the safety limits, thereby providing an immediate visuale*a~uation of the safety of the operation. However, such model displays require ~
:: -i7~3 complicated small mechanisms which are liable to failure and are expensive to~manufacture.
It is an object of the present invention to provide an indicating apparatus in which the above aifficulties are overcome or reduced.
According to the present invention there is`provided indicating apparatus for elevatable and extendible structures comprising first means producing a representation of the angle of elevation of a structure, second means producing a representation of the'length of the structure, electronic display means having a plurality of separately energisable elements arranged in rows radiating from a co~mon point and responsive to the representations from the first and second -producing means for generating a visual display mimicking lS the disposition of the structure, and means associated with the display means for indicating whether t~e 'disposition of the structure satisfies one or more criteria.
The electronic visual display means may include light'-~ emitting diodes, liquid crystal display means or a vacuum fluorescent device. The display means may also include differently coloured areas on the display so that, for example, if all criteria were satisfied the display would be all green, but if a criterion were not satisfied then paxt of the display would be red.
In one example of the invention, the structure is a fire escape ladder and a criterion indicated on the display is a requirement ~or safety against the overturning of the fire engine, this criterion may depend on the load on the fire escape ladder and whether the ladder is to be .. . .
57~3 bridged against a building, for example. The display may include differently coloured sections indicating the safety requirements relative to the different loads.
The invention is also applicable to mobile cranes having extendible booms.
The apparatus may additionally include further means responsive to the representations, such as a logic circuit for producing signals when unsafe combinations of elevation angles and length occur, which signals are used to cause the generation of alarm indications, for example on or adjacent the display or in the-form of a sound drawing attention to the display, and to trigger mechanism which will arrest motion towards such unsafe combinations.
In order that the invention may be fully understood and readily carried into effect, the invention will now'be described with reference to the accompanying drawings, of which:- , FIGURE 1 shows a fire engine having a turntable ladder to which the-invention may be applied, and ~a a~l~/ OZ b , 20 FIGURESZ~ represent~ in diagrammatic form one embodiment of apparatus according to the invention.
Referring now to Figure 1, the fire engine shown has an extendible ladder 1 which is shown extended to a length L and elevated to an angle A relative to the horizontal. The extension of the ladder 1 is carried out by a winch 2 mounted at the bottom of the ladder and linked to the winch 2 by a suitable gearing mechanism is a means for producing an electrical signal representing the 57~3 extension L. Typically this means takes the form of a simple resistive potentiometer of sultably rugged construction for the application 9D that there is obtained from the wiper of the potentiometer a voltage proportional to the length L. The angle A is measured by a second resistive potentiometer coupled to a pendulum, the potentiometer being mounted to rotate with the ladder 1 as it is elevated. Respective potentiometers are used as the means for produclng representations of the length L
10 and the angle A because they provide adequate accuracy and absolute represe~ations of the values. As an alternative to the resistive potentiometers, digitally coded discs or sectors could be used so that digital indications of the length L and the angle A are produce~
15 directly. Such coded discs and sectors should have suitable resolution of the quantity being measured to matchthe resolution provided by the display.
Referring now to Figure 2, the pot~tiometer ,providing a representation of the angle A of elevation 20 of the ladder 1 is shown as the inclinometer 10. The potentiometer producing an indication of the length L
of the ladder is shown as a ladder extension meter 11.
The pot~tiometers are provided with a steady d.c. supply so that they produce output d.c. voltages proportional 25 to the quantities being measured, which voltages are applied to respective analogue to digital converters 12 and 13. The digital outputs from the converters 12 and 13 are quantised, for exarnple by selecting just the most significant five binary digits of the output representations, and the quantised digital outputs appear in parallel on the conductors 14 and 15 respectively. It should be pointed out that because of the need to align the rungs on one section of the ladder with those on the adjacent section the various possible lengths of the ladder are naturally quantised to an integral multiple of the rung spacing.
A signal indicating the rung alignment is produced ~y a 10 unit 16 which is used in conjunction with the quantising of the digital output of the converter 13 to ensure that the quantised outputs of this converter is produced only when the rungs are aligned.:
The digital outputs on the conductors 14 and 15 are 15 applied to a decoder 17 which produces suitable signals for driving the display 18 through display drivers 19.
A logic unit 20 also receives the digital signals on the conductors 14 and l5 and produces outputs which are applied to the display 18 to produce emergency indications~ Tne unit 20 may also be used to operate an audible warning device.
With regard the disp~ay 18 itself, in the ex~nple under consideration this consists of a liquid crystal display having 1~ rows, each of 24 elements disposed so as to radiate frorn a common point. Each row of elernents corresponds to a particular eIevation angle of the ladder and as shown the elevation increments are of 5 above the '''' , `
~2~57~3 horizontal up to 75 together with three rows corresponding to 5, 10 and 17 below the horizontal. The length L of the ladder is shown in 3 rung spacing increments starting from 30 rung spacings and continuing to 99 rung spacings.
The display drivers 19 may be arranged to provide drive signals for each of the angles of elevation together with drive signals for the different lengths of ladder. With such an arrangement the elements would be linked by both circum-ferential and radial conductors so that the desired display would be produced. The display itself would consist of the energisation of all of the elements in the row corresponding to the elevation angle nearest to that of the ladder starting from that nearest the common point along the row of elements as far as that element which corresponds to the length L of the extended ladder. Thus if the ladder were 87 rung or round spacings long and inclined at an angle of between 25 and 30 a row of energised elements indicated by the reference 21 would be displayed. The display has a sector-shaped multi-colour overlay for colouring the energised display elements and has a green section 22, a black section 23, a blue section 24 and a red section 25. The operation of the liquid crystal display is such that an energised element appears as a , different colour from the background which may be white or a neutral colour. As a result of this the energised section 21 will appear to the operator to have green, black and blue sections. Had the ladder been extended further, then the operator would have seen a red section as well.
In addition to the rows of elements mimicking the length and elevation of the ladder, the display 18 includes two further sections in the shape of sectors 26 and 27 which are energised respectively when the elevation of the ladder exceeds 76 and when the elevation of the ladder is more than 17 below the horizontal. The effect of the multi~colour overlay is to cause the sectors 26 and 27 to appear red when energised. Whilst in general the operator would be aware of the angle of elevation of the ladder, it is possible that at night and on an uneven surface or sloping ground the actual elevation of the ladder as measured by the inclinometer on the ladder itself might lie outside the safe range of elevations prescribed for the ladder.
The display 18 also includes a diagram 28 which can be selectively energised to indicate to the operator the safe use of the ladder, for e~ample, one man, two men or three men on a cantilevered ladder, or up to eight men when the ladder is bridged across to a building.
The use of a liquid crystal display would enable it to be read easily in conditions of bright daylight and it could be illuminated for use at night. If ~ ~57~?3 light-emitting diode elements had been used instead, whilst legibility at night would be without difficulty, the display could be difficult to read in bright sunlight. The same objection would apply to other forms of light emitting display. With such displays some form of light shield could be provided to improve legibility.
The display may be arranged to re~uire separate conductors to each element to enable individual energisation of the elements to be provided, in such a case the form of the decoder would be modified accordingly. In another modification the display elements are strobed in a manner similar to that used for calculator displays.
The display may alternatively be arranged so that all the elements corresponding to the indicated length between the angle indicated and the 0~ line are energised. The arc thus displayed provides a bolder indication and may be preferred to a single line of energised areas.
The invention could also be applied to a crane having an extendible boom, and would be particularly useful with such cranes when mounted on a lorry chassis to form a mobile crane.
This invention relates to indicating apparatus for - elevatable and extendible structures and is particularly but not exclusively suited to providing an indication of the position of an extendible ladder on a turntable.
In the use of a turntable it is particularly important that certain safety conditions be observed, under certain circumstances, for example on uneven ground at night,the precise angle of elevation of the ladder may not be so easy to judge and it may be possible for the use to depart from the safe limits. Usually the ladder is designed to operate with one man, two men or two men and a cage and safe limits of elevation and extension in conjunction with the different loads will be defined.
Hitherto, th~re has been provided a display in the form of an analogue scale with the cursor moved in direct relationship to the extension of the ladder together with an analogue or digital meter ind.~cating its elevation. The difficulty with such a display is that the operator must mentally relate the elevation angle indicated on the meter with the extension indicated on the extension scale to decide whether the operation is within the safe limits or not. In another for~ of display, a mechanically operated model ladder is shown against a bac}cground or overlay of the safety limits, thereby providing an immediate visuale*a~uation of the safety of the operation. However, such model displays require ~
:: -i7~3 complicated small mechanisms which are liable to failure and are expensive to~manufacture.
It is an object of the present invention to provide an indicating apparatus in which the above aifficulties are overcome or reduced.
According to the present invention there is`provided indicating apparatus for elevatable and extendible structures comprising first means producing a representation of the angle of elevation of a structure, second means producing a representation of the'length of the structure, electronic display means having a plurality of separately energisable elements arranged in rows radiating from a co~mon point and responsive to the representations from the first and second -producing means for generating a visual display mimicking lS the disposition of the structure, and means associated with the display means for indicating whether t~e 'disposition of the structure satisfies one or more criteria.
The electronic visual display means may include light'-~ emitting diodes, liquid crystal display means or a vacuum fluorescent device. The display means may also include differently coloured areas on the display so that, for example, if all criteria were satisfied the display would be all green, but if a criterion were not satisfied then paxt of the display would be red.
In one example of the invention, the structure is a fire escape ladder and a criterion indicated on the display is a requirement ~or safety against the overturning of the fire engine, this criterion may depend on the load on the fire escape ladder and whether the ladder is to be .. . .
57~3 bridged against a building, for example. The display may include differently coloured sections indicating the safety requirements relative to the different loads.
The invention is also applicable to mobile cranes having extendible booms.
The apparatus may additionally include further means responsive to the representations, such as a logic circuit for producing signals when unsafe combinations of elevation angles and length occur, which signals are used to cause the generation of alarm indications, for example on or adjacent the display or in the-form of a sound drawing attention to the display, and to trigger mechanism which will arrest motion towards such unsafe combinations.
In order that the invention may be fully understood and readily carried into effect, the invention will now'be described with reference to the accompanying drawings, of which:- , FIGURE 1 shows a fire engine having a turntable ladder to which the-invention may be applied, and ~a a~l~/ OZ b , 20 FIGURESZ~ represent~ in diagrammatic form one embodiment of apparatus according to the invention.
Referring now to Figure 1, the fire engine shown has an extendible ladder 1 which is shown extended to a length L and elevated to an angle A relative to the horizontal. The extension of the ladder 1 is carried out by a winch 2 mounted at the bottom of the ladder and linked to the winch 2 by a suitable gearing mechanism is a means for producing an electrical signal representing the 57~3 extension L. Typically this means takes the form of a simple resistive potentiometer of sultably rugged construction for the application 9D that there is obtained from the wiper of the potentiometer a voltage proportional to the length L. The angle A is measured by a second resistive potentiometer coupled to a pendulum, the potentiometer being mounted to rotate with the ladder 1 as it is elevated. Respective potentiometers are used as the means for produclng representations of the length L
10 and the angle A because they provide adequate accuracy and absolute represe~ations of the values. As an alternative to the resistive potentiometers, digitally coded discs or sectors could be used so that digital indications of the length L and the angle A are produce~
15 directly. Such coded discs and sectors should have suitable resolution of the quantity being measured to matchthe resolution provided by the display.
Referring now to Figure 2, the pot~tiometer ,providing a representation of the angle A of elevation 20 of the ladder 1 is shown as the inclinometer 10. The potentiometer producing an indication of the length L
of the ladder is shown as a ladder extension meter 11.
The pot~tiometers are provided with a steady d.c. supply so that they produce output d.c. voltages proportional 25 to the quantities being measured, which voltages are applied to respective analogue to digital converters 12 and 13. The digital outputs from the converters 12 and 13 are quantised, for exarnple by selecting just the most significant five binary digits of the output representations, and the quantised digital outputs appear in parallel on the conductors 14 and 15 respectively. It should be pointed out that because of the need to align the rungs on one section of the ladder with those on the adjacent section the various possible lengths of the ladder are naturally quantised to an integral multiple of the rung spacing.
A signal indicating the rung alignment is produced ~y a 10 unit 16 which is used in conjunction with the quantising of the digital output of the converter 13 to ensure that the quantised outputs of this converter is produced only when the rungs are aligned.:
The digital outputs on the conductors 14 and 15 are 15 applied to a decoder 17 which produces suitable signals for driving the display 18 through display drivers 19.
A logic unit 20 also receives the digital signals on the conductors 14 and l5 and produces outputs which are applied to the display 18 to produce emergency indications~ Tne unit 20 may also be used to operate an audible warning device.
With regard the disp~ay 18 itself, in the ex~nple under consideration this consists of a liquid crystal display having 1~ rows, each of 24 elements disposed so as to radiate frorn a common point. Each row of elernents corresponds to a particular eIevation angle of the ladder and as shown the elevation increments are of 5 above the '''' , `
~2~57~3 horizontal up to 75 together with three rows corresponding to 5, 10 and 17 below the horizontal. The length L of the ladder is shown in 3 rung spacing increments starting from 30 rung spacings and continuing to 99 rung spacings.
The display drivers 19 may be arranged to provide drive signals for each of the angles of elevation together with drive signals for the different lengths of ladder. With such an arrangement the elements would be linked by both circum-ferential and radial conductors so that the desired display would be produced. The display itself would consist of the energisation of all of the elements in the row corresponding to the elevation angle nearest to that of the ladder starting from that nearest the common point along the row of elements as far as that element which corresponds to the length L of the extended ladder. Thus if the ladder were 87 rung or round spacings long and inclined at an angle of between 25 and 30 a row of energised elements indicated by the reference 21 would be displayed. The display has a sector-shaped multi-colour overlay for colouring the energised display elements and has a green section 22, a black section 23, a blue section 24 and a red section 25. The operation of the liquid crystal display is such that an energised element appears as a , different colour from the background which may be white or a neutral colour. As a result of this the energised section 21 will appear to the operator to have green, black and blue sections. Had the ladder been extended further, then the operator would have seen a red section as well.
In addition to the rows of elements mimicking the length and elevation of the ladder, the display 18 includes two further sections in the shape of sectors 26 and 27 which are energised respectively when the elevation of the ladder exceeds 76 and when the elevation of the ladder is more than 17 below the horizontal. The effect of the multi~colour overlay is to cause the sectors 26 and 27 to appear red when energised. Whilst in general the operator would be aware of the angle of elevation of the ladder, it is possible that at night and on an uneven surface or sloping ground the actual elevation of the ladder as measured by the inclinometer on the ladder itself might lie outside the safe range of elevations prescribed for the ladder.
The display 18 also includes a diagram 28 which can be selectively energised to indicate to the operator the safe use of the ladder, for e~ample, one man, two men or three men on a cantilevered ladder, or up to eight men when the ladder is bridged across to a building.
The use of a liquid crystal display would enable it to be read easily in conditions of bright daylight and it could be illuminated for use at night. If ~ ~57~?3 light-emitting diode elements had been used instead, whilst legibility at night would be without difficulty, the display could be difficult to read in bright sunlight. The same objection would apply to other forms of light emitting display. With such displays some form of light shield could be provided to improve legibility.
The display may be arranged to re~uire separate conductors to each element to enable individual energisation of the elements to be provided, in such a case the form of the decoder would be modified accordingly. In another modification the display elements are strobed in a manner similar to that used for calculator displays.
The display may alternatively be arranged so that all the elements corresponding to the indicated length between the angle indicated and the 0~ line are energised. The arc thus displayed provides a bolder indication and may be preferred to a single line of energised areas.
The invention could also be applied to a crane having an extendible boom, and would be particularly useful with such cranes when mounted on a lorry chassis to form a mobile crane.
Claims (12)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. Indicating apparatus for elevatable and extendible struc-tures comprising first means producing a representation of the angle of elevation of a structure, second means producing a repre-sentation of the length of the structure, electronic display means having a plurality of separately energisable elements ar-ranged in rows radiating from a common point and responsive to the representations from the first and second producing means for generating a visual display mimicking the disposition of the structure, and means associated with the display means for indi-cating whether the disposition of the structure satisfies one or more criteria.
2. Apparatus according to claim 1 wherein the electronic display means is a liquid crystal display.
3. Apparatus according to claim 1 wherein the electronic display means is a light emitting display.
4. Apparatus according to claim 1 wherein the means associ-ated with the display means causes the display produced to have differently coloured areas so that the colour of at least part of the display produced when in use indicates what criteria are satisfied by the disposition of the structure.
5. Apparatus according to claim 4 including a circuit responsive to the representations produced by the first and second means to produce a plurality of outputs depending on the disposition of the structure relative to particular criteria, the display means including parts additional to the elements arranged in rows, which parts are connected to be energised by outputs from the circuit to provide warnings in a noticeable colour.
6. Apparatus according to claim 5 wherein the particular criteria are that the angle of elevation of the structure should not exceed a maximum angle of elevation and should not exceed a maximum angle of depression.
7. Apparatus according to claim 5 or 6 including sound generating means responsive to one or more outputs of the circuit to provide an audible warning.
8. Apparatus according to claim 5 or 6 including a mechanism responsive to one or more outputs of the circuit for blocking movement of the structure into an unsafe disposition.
9. Apparatus according to claim 1 in which the structure is a fire escape ladder and a criterion indicated by the display means is a requirement for safety against overturning of the fire engine, wherein the display means includes an indication of the maximum safe load on the ladder for its disposition.
10. Apparatus according to claim 9 wherein the second means which produces a representation of the length of the ladder is responsive to the alignment of the rungs on different ladder sections.
11. Apparatus according to claim 10 wherein the first means is responsive to the angle of elevation of the structure relative to horizontal.
12. Apparatus according to claim 1, 10 or 11 wherein the first and second means each derive an analogue signal from the structure and means are provided for converting the analogue signals to quantised digital signals for operating the display means.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000434127A CA1215793A (en) | 1983-08-08 | 1983-08-08 | Indicating apparatus for elevatable and extendible structures |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000434127A CA1215793A (en) | 1983-08-08 | 1983-08-08 | Indicating apparatus for elevatable and extendible structures |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1215793A true CA1215793A (en) | 1986-12-23 |
Family
ID=4125829
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000434127A Expired CA1215793A (en) | 1983-08-08 | 1983-08-08 | Indicating apparatus for elevatable and extendible structures |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1215793A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9677335B2 (en) | 2014-04-01 | 2017-06-13 | Hme, Incorporated | Firefighting or rescue apparatus including ladder with status indicators |
-
1983
- 1983-08-08 CA CA000434127A patent/CA1215793A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9677335B2 (en) | 2014-04-01 | 2017-06-13 | Hme, Incorporated | Firefighting or rescue apparatus including ladder with status indicators |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |