AU2012238191A1 - Automated control system for a fume cupboard - Google Patents

Abstract

Abstract A system for controlling a fume cupboard (100), the system including: a sash (104) arranged for motorised movement between a stand-by position and 5 an open position that enables an operator access to a compartment (102) of the fume cupboard (100)while partly protected by the sash (104); and a sensor array (270, 273) for detecting the presence of a an obstacle; and a control means (110) for enabling control of the sash (104); whereupon the sash (104) moving from the open position and said detection, a signal is sent from the sensor array (270, 273) to the control means (110) and 10 a further signal is sent from the control means (110) to a sash drive means (260) to reverse the direction of the sash (104) or stop movement of the sash (104). ~lG.NO

Description

AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT ORIGINAL Applicant(s): LABORATORY SYSTEMS GROUP PTY LTD Actual Inventor(s): Max Arbrew Address for Service: PATENT ATTORNEY SERVICES 26 Ellingworth Parade Box Hill Victoria 3128 Australia Title: AUTOMATED CONTROL SYSTEM FOR A FUME CUPBOARD Associated Provisional Applications: No(s),: 2011903630 and 2012900805 The following statement is a full description of this invention, including the best method of performing it known to me/us-- AUTOMATED CONTROL SYSTEM FOR A FUME CUPBOARD Field of the Invention This invention relates to an automated control system for a fume cupboard and more particularly to a fume cupboard in which a sash of the fume cupboard is 5 programmable in a variety of applications, such as setting the sash opening to variable heights and to account for obstacles in the path of the sash. Background of the Invention Fume cupboards are used to enable operators to handle chemicals that can emit dangerous or noxious fumes in a safe manner. Typically a fume cupboard locality or 10 environment is provided with a supply of conditioned air to accommodate extraction for the cupboard and a sash which is a transparent shield or panel which is movable in an up and down direction under the control of the operator to provide further protection against the chemicals. In order to save energy, the sash is kept as low as possible so that less air is needed to flow through the gap from the bottom of the sash to the bottom of the 15 cupboard opening and therefore reduces the air conditioning costs, In order to further save costs, motion detectors have been employed to detect movement of the operator at the fume cupboard. In the absence of an operator the sash automatically closes within a preset time. Other arrangements of fume cupboards stop the sash close to the bottom of the 20 fume cupboard to prevent injury to a person's arms or hands that may extend into fume cupboard. From that low position, the operator can open up the sash manually or electronically using a push button. None of the prior art systems enable control of the speed of the sash up or down nor enable breaking or stopping of the sash at a particular height, A particular 25 disadvantage of the prior art systems is that none enable control of the sash when part of the equipment in the fume cupboard extends in the plane of the sash and can therefore be accidentally knocked over or tripped by movement of the sash downwardly. None of the abovementioned prior art systems disclose a system whereby if an operator is working in the fume cupboard with very little movement that cannot be detected by motion sensors, 30 the user has the ability to control the movement of the sash without having to stop work. It would be an inherent advantage for an operator to continue working whilst controlling movement of the sash in case the sash is on a downward movement. Summary of the Invention 2 According to a first aspect of the invention, there is provided a method of controlling a fume cupboard, the fume cupboard having a sash arranged for motorised movement between a stand-by position and an open position that enables an operator access to a compartment of the fume cupboard while partly protected by the sash, the 5 method including: triggering a sensor array; sending a signal upon triggering the sensor array from the sensor array to a control means when the sash moves from the open position; reversing the direction of the sash or stopping movement of the sash by sending a 10 further signal from the control means to a sash drive means. Preferably the movement of the sash is stopped and/or reversed by the operator obstructing one or more paths of the sensor array to trigger the sensor array to send said signal to said control means. Upon detection by said sensor array of the presence of an article obstructing the path of the sash when the sash moves from the open position, said 15 signal may be sent to said control means upon the sash being sensed within a predetermined distance of the article. The first sensor array may extend across the sash opening of the fume cupboard. The method may further include enabling detecting the presence of a part of the operator by the sensor array. Where the presence of a part of the operator inside the fume 20 cupboard is not detected by the sensor array, the operator can trigger the sensor array to stop or reverse the direction of the sash when the sash moves to within a predetermined distance of the operator. The method may further include enabling the setting of least one working height of the sash. The sensor array preferably includes a series of substantially parallel optical 25 beams generated by a plurality of light emitting devices and received by a corresponding plurality of light receiving devices. The height of the sash can be automatically adjusted to a height above the operator's field of movement, said field of movement being monitored prior to the adjustment of the sash height by said sensor array. According to a second aspect of the invention, there is provided a system for 30 controlling a fume cupboard, the system including: a sash arranged for motorised movement between a stand-by position and an open position that enables an operator access to a compartment of the fume cupboard while partly protected by the sash, 3 a sensor array for detecting the presence of an obstacle; a control means for enabling control of the sash; whereupon the sash moving from the open position and said detection, a signal is sent from the sensor array to the control and a further signal is sent from the control 5 means to a sash drive means to reverse the direction of the sash or stop movement of the sash. According to a third aspect of the invention, there is provided a computer program for controlling a fume cupboard, the fume cupboard having a sash arranged for motorised movement between a stand-by position and an open position that enables an 10 operator access to a compartment of the fume cupboard while partly protected by the sash, whereupon movement of the sash from the open position and triggering of a sensor array, the computer program instructs a processor to: send a signal from the sensor array to a control means, and reverse the direction of the sash or stop movement of the sash by sending a 15 further signal from the control means to a sash drive means. Brief Description of the Drawings Preferred embodiments of the invention will hereinafter be described, by way of example only, with reference to the drawings in which: 20 Figure 1 is a perspective view of a fume cupboard and a controller for controlling the operation of the fume cupboard and operation of a sash of the fume cupboard; Figure IA is an enlarged view of a touch panel of the controller for operating the fume cupboard; Figure 1 B is a screen view of the panel showing the configuration settings 25 accessible by an authorised person; Figure 2 is a flow diagram of the set up and adjustment of a designated working height of the sash, when an operator works at the fume cupboard and when the operator moves away from the fume cupboard; Figure 3 is a pictorial view of the process of control of the sash when an operator 30 moves away from the fume cupboard; Figure 4 is a perspective view showing the components of a working compartment of the fume cupboard of Figure 1; 4 Figure 5 is a view similar to Figure 4 but showing additional components of the fume cupboard; Figure 6 is a plan view showing a first side member separated from a frame to which a sensor array is fitted; 5 Figure 7 is a view similar to Figure 5 but showing the fully assembled working compartment of the fume cupboard including a pair of side members and controller; Figure 8 is a view similar to Figure 6 but showing the connection of one of the side members to the frame in which the sensors are housed; Figure 9 is an enlarged partial perspective view of a portion of a sensor array 10 extending across the sash opening of the fume cupboard; Figure 10 is a pictorial view showing an article that is in the path of the sash of the fume cupboard; Figure 11 is a block diagram of the system used to control the sash of the fume cupboard; 15 Figure 12 is a flow diagram showing the process of an administrator or operator setting a sash working height; Figure 13 is a flow diagram showing the operation of reversing the direction of the movement of a sash when an article is in the direct path of the sash; and Figure 14 is a flow diagram showing the steps involved in stopping or reversing 20 the direction of the sash upon the operator moving a part of their body in the path of a further sensor. Detailed Description of the Preferred Embodiments With reference to Figures 1 and 1A, there is shown a fume cupboard 100 that has a working compartment 102 which is accessible underneath a generally transparent front 25 glass face, otherwise termed a sash 104. Side members 106, 108 are located on respective sides of the working compartment 102. Located on side member 108 is a fume cupboard controller or control means 110 which is controlled by an operator of the fume cupboard 100. The controller 110 has a processing unit which is controlled by a computer program. The controller 110 includes a touch screen interface or panel 112, an 30 emergency isolator button 111 and an iris sensor 115 which includes a sensor. The emergency isolator button 111 is used when an operator requires immediate shut down of the fume cupboard 100, The button is pressed firmly in order to activate it which will then show a status message in notification bar 133 in the touch screen panel 112. The 5 lights will turn off and all electrical outlets are isolated so that no power is delivered to the fume cupboard 100. All flammable gases are shut off and the fan is then run at maximum speed. In order to reinstate operation of the fume cupboard, the button 111 is rotated in the direction of the arrows on button 111 which will then release and pop out 5 of its shut down position. A pre-purge cycle is then performed for approximately one minute and during this time, while the air flow is stabilised, the fume cupboard is not able to be operated, Once the pre-purge cycle finishes, then manual selection or operation is required to reactivate the fume cupboard 100. The touch screen panel 112 has a number of controls that can be operated by an 10 operator. Included on the panel 112 is a configuration settings button 117, a run/stop button 119, a light icon 121, an 'open sash' or 'close sash' icon 123, a 'spray bar' icon 125, a 'services' icon 127, a clock 131, an airflow indicator 129 and a notification bar 133. The icon can be shown in a particular colour, such as grey, to indicate that that function is not available. If the function is available, the icon can be shown in white. Is The run/stop icon 119 when pressed operates the fume cupboard. It will turn the light on and initiate any pre-purge routine. The fan moves to full speed to start air movement and start the air flow. The air speed is continuously monitored and the fan speed adjusts to a face velocity of 0.5 m/sec. The pre-purge routine lasts for approximately one minute. During this time no flammable gas or electrical service is 20 available. To switch the fume cupboard light on or off manually, the light icon 121 can be depressed. When the light is on a tick symbol will be seen next to the icon. The light can also be controlled by an automatic function such that if there is no activity within the opening of the fume cupboard, the light will automatically switch off after a pre-set 25 period of time, To turn the light on automatically, one places their hand into the sash opening or raises the sash by either manual or automated movement. The services icon 127 enables an operator to turn the services on or off. When initially turning the services on, all the electrical outlets and flammable gases are not immediately available. They will become available at the completion of the pre-purge 30 stage just described, For the duration of the pre-purge and in any alarm condition, the services icon is greyed out. Once that time has elapsed and the airflow is stabilised and at the correct rate, the icon becomes solid, that is, white. When the services are on, a tick 6 is displayed next to the icon. This button is not used to provide any control over the type of service available, such as water services or non-flammable gas types, The spray bar icon 125, which may or may not be fitted, can be pressed to activate a spray bar function. The fume cupboard 100 will then turn a spray wash behind 5 the baffle and wash residue from behind the baffle. It will remain on until the icon is pressed off. When the fume cupboard is stopped the system performs a timed wash, of which the duration is programmable under the administrator settings, Depressing the configuration settings button 117, provides access to the screen shown in figure 1B. The screen provides access to an administrator to amend the time 10 and date through icon 135, an administration icon 137, a services icon 139 and a factory set icon 141 Each of the icons once depressed require the administrator or operator to enter a password. The operator, on depressing icon 135 and entering a password can amend the time and date visible to the operator of the fume cupboard which includes adjusting the hour, minute, day, month and year through up and down buttons on the 15 keypad, Once all of the values have been set the operator presses a tick icon and returns to the settings screen shown in figure IB. To return to the home screen button 143 is depressed. After a time out the unit automatically returns to the home screen. Daylight saving time can also be programmed into the unit. Depressing the administration setting icon 137 provides access to administration 20 login screen where the operator enters a password. Administrator settings are then displayed including the sash working height, the sash close timer and the light close timer. The sash working height is the height to which the sash 104 will automatically be positioned at for the user to use the fume cupboard 100 with protection. In order to adjust this working height, the operator depresses the current working height value icon 25 upon which is displayed the working height adjust screen. The current working height is displayed above the numerical keypad which is used to enter a new sash working height. This value then also appears at the top of the keypad alongside the current working height. The allowable height range is 100mm to 700mm. When the desired sash working height is entered a tick icon is depressed and the operator returns to the 30 administration settings screen. The sash close timer value is the period of time at which the fume cupboard will perform an automatic adjustment of the sash position to an optimum height, based on the monitored working height of the user. This height provides increased protection to the 7 operator and reduces the amount of air conditioning drawn through the fume cupboard 100. To change this height the operator presses the sash close timer icon using up and down arrows to adjust the timer value, Values between 5 and 60 minutes are allowable. Once entered a tick icon is pressed to save that value and the screen returns to the 5 administration screen, The light timer value is the period of time to which the fume cupboard light will automatically turn off. In order to change this period of time, the light globe icon is depressed and the timer value is adjusted by using the up and down arrows. Again allowable times are anywhere between 5 and 60 minutes and once the value is entered a 10 tick icon is depressed to save this value. The screen then returns to the administration screen, The notification bar 133 is a strip that runs the full width of the bottom edge of the screen or panel 112. This is where error messages are displayed or service due messages and filter messages are displayed, The alarm displays can be accompanied by an audible sound such as a beep which can be muted by pressing an area on the screen. 15 Typical errors that can occur are low air flow, an emergency stop and power failure. The fan status icon 129 can indicate a different colour for different states. For example red indicates that no air flow exists or there is an alarm condition. A yellow icon indicates that the fan is spinning, air movement is detected and the air speed is being adjusted. A green fan icon can indicate that the minimum air speed is being detected and 20 that it is ready to operate the cupboard. Iris sensor 115 can act as a motion sensor or there may be a separate motion sensor, so that within a predetermined distance of sensor 115 or the controller 110, for example between 4 mm and 20mm, of sensing a part of an operator such as a hand or finger, the sash 104 can move up or down accordingly. Separate indicator lights (for 25 example coloured LEDs) can be used to distinguish when to program the sash 104 to go up and when to go down. If the sash is shut or in a stand-by position, a hand can be waved in front of iris 115 of controller 110 to open the sash 104 to a pre-set maximum height. If the sash is fully open, a hand can be waved in front of the iris 115 of controller 110 to close the sash 104. If the sash is partly open, a hand can be waved in front of iris 30 115 of controller 110 to open the sash to a pre-set maximum height. In all other instances, the user would have a hand or two free to use the touch panel 112 to provide the necessary controls. 8 Assuming the fume cupboard 100 is on and the sash 104 is in the stand-by, down or closed mode, an operator can use the controller/interface 110 to move the sash 104 as follows. The sash 104 can be opened or closed by manual operation or automatic operation. Manual movement involves placing one's hand on the sash handle at the 5 bottom of sash 104 and pushing or pulling the sash up or down to the desired height. The movement of the sash can be done automatically by use of either the touch display panel 112, the iris sensor 115 or movement in the sash exclusion zone. The sash exclusion zone is an area within the compartment which is above the working field. The working field is generally at the lower part of the compartment. The controller, as guided by the 10 program continually monitors any movement so that the sash opening can be reduced to the safest possible minimum height (optimum height). The sash has a settable working height and a factory set loading height as well as a closed height. The sash can be moved at any time. When the fume cupboard is in use by an operator, the controller analyses and detects movement in the sash plane. If movement is contained to the working field 15 (green) then the sash will remain where it is as long as the motion is detected. If the operator conducts sufficient movement in the exclusion zone, then the program will react to make the motor increase the sash height to provide a larger working area. After a period of time, if no movement is detected then the sash will close from the current position to the minimum required sash opening in order to save energy. If at any point in 20 the transit to the closed height/opening an obstruction is detected, the sash travel will stop automatically in order to avoid a collision. The fume cupboard 100 has three pre-set positions to which the sash can be located. The first position is the loading position which is factory set, the second position is a working height which is set by an administrator and the third position is a 25 closed position which is factory set. Referring to the panel 112 and to the icon 123 which states 'open sash', the open sash icon 123 will be displayed any time that the sash is at the closed position. This icon is depressed to move the sash to the working height position. Alternatively the 'closed sash' icon-would be displayed at any time that the sash is not at the closed position. The 'close sash' icon is then depressed to move the 30 sash to the closed position. The iris sensor 115 can be colour-coded to indicate a number of positions. For example a first colour, blue, indicates that the apparatus is in in a standby position while a second colour indicates another position, The operator places a part of his/her hand 9 over the iris 115 until the glow or colour turns to mauve. The user then moves their hand away and the sash 104 will move to the loading position. Once it has reached the loading position the iris 115 will then change back to the standby blue colour, The working position is indicated by the colour green so that by the operator placing a part of his/her 5 hand over the iris 115 until it turns green, will then move the sash 104 to the working height position. The operator then moves their hand away. After a time, the iris 115 will then change back to the standby blue colour. When the iris 115 indicates a further colour white, this means that the sash is moving to the closed position. The operator places a part of his/her hand over the iris 11 until it turns to this colour white and then moves 10 his/her hand away. The sash moves to the closed position and the iris 115 will, after a time, turn to the standby blue colour. In order to raise the sash 104 to the next pre-set position, that is loading, working height, the operator places their hand in the exclusion zone for approximately three seconds where a beep will sound and then the sash will begin to move. The operator 15 should remove their hand once the sash 104 begins moving. The exclusion zone is positioned about the mid-point of the working compartment or at a suitable height, Whenever the sash 104 is not at the closed position, a timer is active and a countdown is shown on the 'close sash' icon which would be in position 123 on panel 112. This depicts the time in minutes to which the fume cupboard will perform an auto 20 adjustment of the sash 104. When there is 60 seconds to go, the timer will display in seconds and when there is 10 seconds to go, a beep will be heard if adjustment is required. The sash will then move to its best measured position depending on the operator's arm or hand position. This is as a result of analysing and recording over time, the movements of the operator to establish a safe working position while allowing 25 enough room for the operator to work at the fume cupboard 100. The timer is able to be preset by the administrator for the sash 104 to automatically close. When errors occur the iris 115 will glow a red colour to indicate any of the possible enrors being a low air flow, an emergency stop condition, the controller not being on, the motor being stalled, the sash colliding with an object. 30 In order to stop the sash 104 when it is automatically moving down or closing, the operator simply moves their arms or body part underneath the sash handle (at about 40 80mm). To make the sash 104 stop from a downwardly moving position, the operator 10 moves an arm or another body part underneath the sash handle (at about 3 0-40mm). The operator can theno raise the sash 104 to a pre-set height position, Referring to Figure 2 there is shown a flow diagram 200 of the setup, approach and working at the fume cupboard as well as a last step of describing the operation of the 5 sash 104 when the operator moves away from the fume cupboard 100, As described partly already, the set up step involves an administrator/ operator setting the sash operator working height entered in the keypad of display 112 of the controller 110. This height will generally be suitable for use by a range of users of the fume cupboard 100. The sash 104 is then moved by the operator to the desired height 10 either manually or electrically at step 202 and at step 204 the administrator/operator sets the working height on the controller 110 through icon 137. Thus the sash 104 will move automatically to the working height On approach to the fume cupboard 100 the sash 104 remains in a standby position. The user presses the open sash icon 123 to move the sash 104 to the working is height on the controller 110 at step 206, At step 208 the sash 104 is in the set working height position. The operator can also use iris sensor 115 (as previously described) to electrically move the sash 104 at step 210 so that the sash is in a loading position or the working height position at step 212. A sensor, known as a tripping sensor, automatically opens the sash 104 to the last working height or the default height at step 214 upon the -20 user tripping the sensor. When the operator is working within the fume cupboard 100 a sensor, comprising a number of light beams, is triggered during use in order to keep the sash 104 open at step 216. At step 217, the sensor beams across the front of the work compartment 102 and in front of (or behind) sash 104, sense the user's movements over a set time, for 25 example a few hours or a day, which are recorded by a processor in the controller 110, Based on the recorded movements, such as the height variation of the user's arms, the controller 110 may adjust the working height of the sash 104 specific to that user to an optimal height that is both safe for the user to work and saves energy by keeping the sash opening to a minimum height and therefore requiring less air conditioning to operate 30 within the fume cupboard 100 (Green-Safe@ mode), The adjustment can be made automatically or at a set time of the day, with an audible alarm 328 (see Figure 11) and visual indication 326 (see Figure 11) to alert the user that the sash 104 is moving to the new position. At step 218 the user can adjust the height of the sash 104 as required either electrically or manually and then at step 220 the sash is in a desired working height position. The sash can also respond to move to the Green-Safe@ mode as described above. If the user does not activate the sensor array and the sash 104 is about to close or adjust into a range that is not suitable to the user, then the user may move their arms or 5 another body part into one or more of the beams in the sash stop or reverse area, which is within the bottom 80 to 100 mm zone from the lower sash handle edge, to stop closure of sash 104, to be explained hereinafter. At any time the sash 104 can be manually moved to any position. This applies particularly in situations where AC or mains power is not supplied to the fume cupboard 100. 10 When the user or operator moves away from the fume cupboard 100 at step 222, such that the operator has stopped working at the fume cupboard 100 or is away from the cupboard 100 for a period of time and the sensor arrays 270, 273 detect no movement, then after a predetermined period of time or immediately at step 224, a timer is activated (referring to Figure 3). At step 226 visual and audio alarms 326, 328 are activated after a 15 predetermined time or during the timer countdown. At step 228 the sash 104 automatically closes to a predetermined standby height. Typically the standby closed height would be between 50 mm and 100 mm, typically 100 mm, above the sill of the fume cupboard 100, Referring to Figure 4, there is shown the working compartment 102 of the fume 20 cupboard 100. It shows the sash 104, and electrical board 250, and a pair of stainless steel runners and pulleys 252 which guide a corresponding cable to move the sash 104 up and down. There is also shown a base trim moulding 254, a pair of sash guide rails 256, 258, and a sash drive motor 260. An outlet 262 is disposed on the top part of the working compartment 102 for exhaust of fumes and dust and the like, Lead 264 connects 25 from a source of power to the controller 110. A pair of leads 266, 267 respectively connect to the sensor array that extends across the sash opening with one lead supplying power to the transmitter and the second lead supplying power to the receiver. Referring to Figures 5 and 6, the side members 106, 108, otherwise termed mullions, provide support and cover for the cables 266, 267 as well as cable 264 that 30 leads to the controller 110. Controller 110 mounts on the side member 108. A series of laser diodes or LEDs are provided at one side of the sash opening and extend along the full length of the fume cupboard. This series represents the transmitting part of the sensor array that extends across the sash and is shown at Figure 6 as numeral 270. Figure 12 6 is a plan view and therefore the series of LEDs extends downwardly into the page. The LEDs are generally spaced at about 13.2 mm but this distance can be varied. The series of emitting diodes 270 can fit within bracket 272 and are supplied power through lead 267. Extending substantially perpendicular to the front face of the sash 104 is a 5 projection 271 which acts as a shield and blocks the path of the light from one or more LEDs as it is moving downwardly. The position of the bottom of the sash 104 can therefore be determined by the number of LEDs that have their emitted light blocked by the projection 271, which will be explained hereinafter with reference to Figure 9. Located on the other side of the fume cupboard in a bracket similar to bracket 272 is a 1o series of light receiving devices such as photo-diodes that respectively receive one of the beams from a corresponding LED in the series of LEDs 270. The series of photo-diodes that receive the corresponding light are separately provided power through lead 266. If needed, an additional projecting element similar to projection 271 can be supplied at a corresponding location adjacent the series of photo-diodes on the other side of the fume 15 cupboard to what is shown in Figure 6, The sash 104 fits within side brackets, one of which is shown 274 which mounts, together with bracket 272 to the working compartment 102. A set of power points 276, 278 respectively fit within.or to side members 106, 108 and have separate cables 277, 279 respectively. The series of light emitting devices 270, series of light receiving devices 273, the 20 projection/shield 271 near devices 270 and corresponding projection/shield near the light receiving devices 273 can be located behind the sash 104, that is on the inside adjacent the working compartment, Referring to Figure 7 there is shown the completely assembled working compartment 102 with side members 106, 108 fitted to the respective sides of the 25 working compartment 102. The operator can stop or break the movement of the sash 104 and have the sash stop where it is required by depressing icon button 123, or covering iris detector 115 discussed previously, or by positioning part of their body within sensing distance of button/sensor 115. This can also be activated in situations where the sash 104 inadvertently moves downwardly to a closed or unused position and the operator wishes 30 to halt that movement or raise the sash 104 to the higher level. Figure 8 shows a fully assembled side member 106 having a flange 284 which fits within a slot 286 of bracket 272. 13 Referring to Figure 9, a sensor array is disposed at the front of the fume cupboard across the sash opening whereby a number of transmitters, in the form of light transmitting devices 270 transmit beams of light 290 to be received by a corresponding receivers, each in the form of a light receiving device such as a photo-diode. The sensor 5 array may equally be disposed behind the sash 104 at the front of the fume cupboard. The receivers are collectively shown as a series of photo-diodes that make up a receiver array 273 on the right side of the sash opening and are (optionally) affixed within a corresponding bracket that attaches to the side of the work compartment. The series of transmitting LEDs 270 and light receiving devices 273 are generally spaced at 13.2 mm 10 apart but this distance can be made smaller or larger to suit. In order to spread a beam emanating from each of the source LEDs, a collimator or spacer may be placed in the path of each beam that is emitted from each one of the LEDs. Thus, as the light is generated by the transmitter array 270, the field of transmitted light spreads to the receiver array 273, allowing the spreading light to fill the opening to the fume cupboard 15 100 in which the sash 104 moves up and down. Each collimator spreads the beam so that effectively the whole sash opening is covered with the spread of the beams and therefore any obstruction or movement can be detected in the sash opening. The separation from the spread of one beam in the sash opening to the spread of an adjacent beam in the sash opening can be as small as Imm. Each of the beam locations and therefore the diode 20 locations are recorded in memory. For example, beam 1 may be the lowest beam in the sash opening and therefore has a predesignated distance from the bottom of the sash opening or the bottom of the fume cupboard. The uppermost beam may be for example beam number 100 and therefore represents a distance of the full sash opening. In order to detect the exact position of the bottom ledge of the sash 104, the processor is able to 25 compute how many beams have been broken by the projection 271 as the processor monitors the status of each beam and can therefore determine the position of the sash 104 by noting the uppermost beam that is not broken and comparing this in memory to find its corresponding distance above the bottom of the sash opening. If the sash needs to be moved to a predefined user position then a similar calculation is made by determining 30 how many beams need to be unbroken or restored by comparing the set sash opening distances stored in memory which were input initially by the administrator/operator. The exact location is stored in a memory associated with the processor. If power is disconnected to the fume cupboard for some reason, then when power is restored, the 14 position sensor can identify exactly where the sash is and software is used to control the processor to move the sash to a number of positions, such as closed, or to a designated open position at a particular height, such as a loading position or working position. Although the light transmitting devices 270, light receiving devices 273, 5 projection 271 and bracket 272 are shown in front of the sash 104, these can be placed in other positions, such as behind the sash 104. In pulsing of the LED array, "triangulation" can be used to monitor the sash 104 opening plane through the locations of the LEDs. The spread of this "triangulation", from a transmitting device to a horizontally opposed receiving device can be in the 10 vicinity of 25 degrees, allowing other receivers to monitor transmission of light not emanating from directly opposite the corresponding receiver. This provides an intensive array field for the sash 104 plane at the opening and ensures that the complete sash 104 opening is monitored for movement of the sash 104, any obstructions or movement in the path of the sash 104. 15 Where part of the equipment in the work compartment 102 protrudes outside of the plane of the sash 104, that is, outside the working compartment, for example an obstacle presented by a handle of equipment, its exact position will be sensed by one or more beams as the handle blocks the beam or beams. When the sash 104 is moving downwardly towards the obstacle in response to no movement (fixed handle), if no alarm 20 is activated or signal sent, the sash would hit the handle and dislodge it from a stand or move it within the compartment. This presents a risk to an operator by potentially exposing the operator to spilling chemicals that could be, for example in a pot, or movement of the equipment could dislodge other chemicals. Therefore in order to avoid this, an audible and visual alarm 328, 326 is triggered when the sash 104 starts a 25 downward movement. This can alert the operator to move the obstacle, in which case the operator breaks a number of beams above the obstacle to send a signal to the processor to stop the movement of the sash and/or reverse the movement of the sash to its former position. The alarms 328, 326 then stop. Where an operator is not near the fume cupboard, and an obstacle is in the path of 30 the sash 104 as it descends from an open position, the audible and visual alarm 328, 326 is activated and when the bottom of the sash moves to within a predetermined distance of the obstacle it will send a signal to the processor which will stop the sash drive motor 260 and therefore stop movement of the sash 104. As an example, if the beams are 13.2 15 mm apart, the range of detection can start at 50mm above the obstacle which will be 5 beams or 5 diode positions. Therefore as the processor already knows the position of the obstacle, it will receive signals from the sensor aray as each beam is subsequently blocked by projection 271 by downward movement of the sash 104. Therefore the 5 number of beams or diodes is counted as being blocked and when the bottom of the sash 104 reaches the fifth beam above the obstacle it will stop the movement of the sash 104. The alarm can still be activated until the obstacle is moved or after a predetermined amount of time, the sash may move to its original position Had the operator been within range of the fume cupboard, the operator could 10 wave a hand or elbow (if their hands are full) in a zone above the stop zone. That is, the next 5 diode positions, being diodes 6 to 10, which span a distance of 50mm above the original 5 beams above the obstacle. By breaking any one of those beams 6 to 10, it can be sensed by the processor to then send a signal to the sash drive motor 260 to stop or otherwise reverse movement of the sash 104. 15 If an operator is working with equipment in the fume cupboard 100 with their arms or hands primarily in for example, the bottom most 20 beams, that variation in position will be sensed by the processor in the controller. The sash may be opened to either a suitable loading height or working height which had been pre-programmed by the particular operator, Over a period of time, the user's movements are tracked to 20 determine which beams have remained unbroken and which beams have been broken and a safe and energy saving position of the sash can be determined. As previously explained this may be recorded and determined over a preset time, such as over a period of hours or days, and the movement of the sash to that predetermined safe and energy-saving position can be done at a particular time of the day or may be done through an alarm 328, 25 326 which gives an indication to the user that the sash is about to move to that position. The sash movement is then counted by the number of beams it breaks downwardly until it reaches the Green-Safe@ position. The audible alarm 328 and/or visual alarm 326 are triggered before the sash height adjustment is initiated. Therefore the operator's real time working area or zone is determined as a result of the sensing system determining 30 where the operator is actually working. Thus as an example, if the sash 104 is already set at 400mm above the base of the working compartment 102, and the operator has only been using the lowest 200mm for the whole time he or she has been working, the laser diodes and the beams provide information of where the operator has been working and 16 can set a new working height for the sash 104 to move to, by sending signals to the processor 320 which in turn, under the action of the computer program instructs the sash drive motor 260 to move the sash 104 to the new height. The sash 104 is then adjusted accordingly to the new height. Text indicated on the controller or some other indication 5 on the controller 110, even via one of the alarms 326, 328, can be provided to the operator to alert the operator that the new height is being set to the height determined by the processor in the Green-Safe@ mode. Examples are shown in Figure 10 where an operator 300 is using a pot 302 that has a handle 304. The handle 304 breaks the plane of the sash 104, in the up/down 10 direction, and it can be seen that if a continued downward movement of the sash 104 is allowed, then it will hit the handle 304 and dislodge its contents. Thus the software operates with the controller processor and the sensor array 270, 273, 290 in order to avoid this situation. The diodes in each array of diodes 270 and 273 are shown in front of the sash 104, but can be located behind the sash 104, The beams 290 can vary in 15 number and the spacing between each of the beams can also be varied. Again, if the operator is working near the bottom of the cupboard and the sash is on a downward movement, the sensor array determines that there is an obstacle in the path of the beams, As soon as it is within five beams (e.g. 50mm) of the operator it will stop. The five beams above the stop zone (50-100mm above) can be used by the operator 20 to stop or reverse the sash movement, If for some reason the sash does not stop the downward movement, as soon as pressure is brought to bear against a part of the operator, for example their arm, the sash 104 stops operating. It can be manually raised or by the operator raising their arms into beams above where he/she is working, Each user can access their own preset heights of the sash 104 by logging/checking 25 in, typically with a swipe card. This will open the sash 104 up to the predetermined or preset height. This provides a built in mechanism so that the sash 104 does not open up automatically if another person walks closely by the front of the fume cupboard. In order to open the sash 104, the fume cupboard 100 can require a specific log in procedure or use of a swipe card by a verified user, As an alternative, the working height or multiple 30 working heights can be set by an operator or administrator specific to that operator. By entering a unique ID in the keypad of panel 112, the stored height or heights of the sash 104 can be attained on depression of the 'open sash' icon 123, The specific working height can be stored in a memory of the processor of controller 110. The fume cupboard 17 100 is able to be used by handicapped persons, for example in a wheelchair, with the controller 110 located at a height which is reachable by such a handicapped person, The sash 104 can be opened manually by pressing the up-down icon 123 or being sensed by the button 115. 5 Referring to Figure 11 there is shown a block diagram of the control system 300 used to operate the fume cupboard sash 104. The user interface or controller 110 is associated with control PCB 310 upon which is configured a control processor 320 and associated memory 322 within which the aforementioned computer program is stored. The control PCB 310 may be unitarily formed with the user interface/controller 110 or 10 alternatively be separately configured with a wired interconnection between the two. The control processor 320 and the memory 322 may also be unitarily formed and, for example, be implemented by an appropriately programmed microcontroller device. The processor 320 responds to commands stored in the memory 322 to undertake particular actions. The controller processor 320 is linked to the sensor arrays 270, 273, 290, the 15 aforementioned visual alarm 326 and audible alarm 328 and to the sash drive motor 260, A fan exhaust 312 is linked to an inverter 314 which are both linked to the control PCB 310. The fan inverter 314 is used to control the speed of the fan exhaust 312 upon receiving signals from the processor 320. The sash drive motor 260 preferably operates at a constant speed to move the sash up and down at a constant rate. The inverter 314 is a 20 variable frequency inverter which controls the fan exhaust 312 depending on the position of the sash 104. For example, a scale of 0 volts to 10 volts may be used, where 0 volts represents the sash being fully closed and 10 volts representing the sash being fully open. Upon determining the position of the sash 104, for example at or near the top of the fume cupboard 100 so that the sash 104 is fully open, the inverter 314 would operate on 25 instruction from the processor 320 at 10 volts which therefore operates the fan exhaust at a higher frequency such as 50Hz in order to consume or exhaust a greater amount of air in the fume cupboard. If the sash position was lower down closer to the bottom representing nearly 0 volts for the inverter 314 then this would make the inverter 314 control the fan exhaust motor 312 to operate at a lower speed, for example at a frequency 30 of 25Hz. This would be the situation where the air to be consumed/expelled is less. The processor 320 or control PCB 310 records the position of the sash 104 and, based on this information, determines the speed of the fan exhaust motor 312. The speed of the sash 104 travel can be made adjustable by drive ratio changes. 18 Thus the PCB 310 includes an isolated analogue OV tolOV output, It is intended that this signal be used to adjust air conditioning in accordance with fume cupboard exhaust airflow. Rather than supplying a proportional analogue signal that is a percentage of the maximum air flow of a cupboard, the software provides a signal that 5 has an absolute airflow scaling factor representing actual airflow through the exhaust duct, Therefore 10V is equivalent to 50,000 litres/minute (50m 3 /min) or 5m 3 /min per volt. Using an absolute scaling factor means that operators will receive a consistent signal regardless of the size of a fume cupboard installed, An installation with a mixture 10 of cupboard sizes can provide the system with multiple outputs that can be added together to determine the total air flow out of the facility without having any knowledge of the sizes of the cabinets installed. As an example, an installation with 1.Om x 1,5m and 1.Om x 2.0m fume cupboards may have airflows of 15,000 1/min and 25,000 I/min respectively, The outputs would be 3V and 5V respectively giving a total air flow of 15 (3+5) x 5,000 which is equivalent to 40,000 1/min or 40m 3 /min. An analogue out signal being VSD Hz is represented on a 0-10 volt scale, This analogue signal is sourced directly from the VSD as a representation of the current frequency that the motor is running out. The system requires the maximum motor frequency to be set at 60 Hz giving a scaling of OV= 0Hz and 1 OV=6OHz. 20 Referring to Figure 12 there is a flow diagram 400 showing how an operator can access the system to set a new working height of the sash 104. At step 402 the operator accesses the configuration settings through icon 117 on the touch screen panel 112. At step 404 the operator then accesses the administration icon on the panel and at step 406 enters a password on the numerical keypad that is subsequently shown. If the password 25 is rejected at step 408 the operator may enter a limited number of password retries at step 410. If this is not successful then access is denied to the operator, If the password is accepted at step 408 the process moves to step 411 where the administration settings are displayed, At step 412 the operator may enter a new working height, a new sash closing time or a new time value where the light will switch off, by using the keypad and 30 prompts. At step 414 the controller 110 senses any changes made to each of the values identified in step 412 and these are stored in memory 322, Thus a person accessing the fume cupboard can press on the 'open sash' icon 123 which will automatically open to the working height as stored in memory and input by the operator. 19 Referring to Figure 13 there is shown a flow diagram 500 which describes the control of the sash through the computer program and processor 320. At step 501, no movement or presence of an operator is detected by the sensor array 270, 273, 290 for a pre-set time, If at step 502 the sash 104 is on a downward movement and there is some 5 part of equipment that is protruding through the plane of the sash 104, such that it would obstruct the closing of the sash 104, then at step 504 the protruding part of the equipment is sensed by the sensor array 270, 273, 290 to be in the path of the sash 104. At step 506 an alarm 326 or 328 is triggered by the processor 320, under instruction from the computer program, after a signal is sent from the sash position and interference sensors 10 270, 273, 290 to the processor 320. At step 508 a determination is made by the sensors 270, 273, 290 and processor 320 as to whether the operator is present, If the operator is sensed as being present, the operator can place a part of their body, usually hands or elbow or arm in the path of some of the beams 290, which is sensed by the sensors 270, 273, 290 and a signal sent to the processor 320, in order enable the processor to instruct 15 the sash drive motor 260, under instruction from the computer program stored in memory 322, to reverse the direction of the sash 104 or to stop the sash 104 from moving at step 509, Alternatively the operator can move the obstacle out of the way. Also the operator can cover the iris sensor 115 to cycle through any of the programmed heights of the sash 104 (colour-coded) as described previously. 20 Thus, at step 510 a signal is sent upon detection of part of an operator's body to the processor and the computer program instructs the processor 320 to send a signal to the motor 260 to stop or reverse the direction of the sash 104. At step 511 the motor 318 is able to reverse the direction of the sash 104. If the operator is not sensed by the sensors 270, 273, 290 as being present or near 25 the fume cupboard 100 as determined at step 508, then at step 512 the bottom of the sash 104 will continue to move to within a number of beams 290 above the obstacle. The sensors 270, 273, 290 sense the distance between the bottom of the sash 104 and the top part of the equipment. A signal from the sensors 270, 273, 290 is then sent to the processor 320 to indicate that the sash 104 is about to hit or connect with the protruding 30 piece of equipment. This is done at step 514, The processor 320 then, under instruction from the computer program sends a signal to the motor 260 at step 515 to stop the sash 104. At step 516 the motor 318 stops the movement of the sash 104. When the operator 20 returns, the operator can manually move the sash 104 or provide inputs to the controller 110 to move the sash 104 back to the working height. With reference to Figure 14, there is shown a flow diagram 600 of the process for controlling the movement of the sash 104 upon detection of the operator working in the 5 working compartment 102, The flow diagram 600 starts at step 602 where the sash 104 is on a downward movement about to close or go to its standby height, At step 604, the sash 104 moves within the beams 290 and when at step 605 when the sash 104 is within a predetermined number of beams 292 above the operator as sensed by the sensors 270, 273 and 290, and the operator is working at the fume cupboard and cannot move for 10 some reason, the sash will be directed to stop or reverse direction through steps 610, 612 and 614. Alternatively, the operator at any time on the downward movement at step 608 can move part of their body to interrupt a number of beams above where the operator was working to stop or reverse the travel of the sash 104 or raise a hand in the exclusion zone for about 3 seconds to enable the sash to move to the next pre-set position, such- as is loading position or working position. The movement of the body part of the operator is sensed by the sensors through the beams 290 at step 608. At step 610 a signal is sent from sensors 270, 273 to the processor 320. The processor 320 then under the action of the computer program stored in memory 322, sends a signal to the motor 260 at step 612 to stop or reverse the direction of travel of the sash 104 and then at step 614 the motor 20 260 stops or reverses the direction of the sash 104. The user is then ftee to continue working or to adjust the sash 104 to the predetermined height. 21

Claims (21)

1. A method of controlling a fume cupboard, the fume cupboard having a sash arranged for motorised movement between a stand-by position and an open position that 5 enables an operator access to a compartment of the fume cupboard while partly protected by the sash, the method including: triggering a sensor array; sending a signal upon triggering the sensor array from the sensor array to a control means when the sash moves from the open position; and 10 reversing the direction of the sash or stopping movement of the sash by sending a further signal from the control means to a sash drive means.

2. A method according to claim I wherein the movement of the sash is stopped and/or reversed by the operator obstructing one or more paths of the sensor array to 15 trigger the sensor array to send said signal to said control means.

3. A method according to claim 1 or claim 2 wherein upon detection by said sensor array of the presence of an article obstructing the path of the sash when the sash moves from the open position, said signal is sent to said control means upon the sash being 20 sensed within a predetermined distance of the article,.

4. A method according to any one of the preceding claims wherein the first sensor array extends across the sash opening of the fume cupboard, 25

5. A method according to any one of the preceding claims including enabling detecting the presence of a part of the operator by the sensor array.

6. A method according to claim 5 such that where the presence of a part of the operator inside the fume cupboard is not detected by the sensor array, the operator is able 30 to trigger the sensor array to stop or reverse the direction of the sash when the sash moves to within a predetermined distance of the operator. 22

7. A method according to any one of the preceding claims further including enabling the setting of least one working height of the sash.

8. A method according to any one of the preceding claims wherein the sensor array 5 includes a series of substantially parallel optical beams generated by a plurality of light emitting devices and received by a corresponding plurality of light receiving devices.

9. A method according to any one of the preceding claims wherein the height of the sash is automatically adjusted to a height above the operator's field of movement, said 10 field of movement being monitored prior to the adjustment of the sash height by said sensor array.

10. A system for controlling a fume cupboard, the system including: a sash arranged for motorised movement between a stand-by position and an open 15 position that enables an operator access to a compartment of the fume cupboard while partly protected by the sash; and a sensor array for detecting the presence of a an obstacle; and a control means for enabling control of the sash; whereupon the sash moving from the open position and said detection, a signal is 20 sent from the sensor array to the control means and a further signal is sent from the control means to a sash drive means to reverse the direction of the sash or stop movement of the sash.

11. A system according to claim 10 wherein the movement of the sash is stopped 25 and/or reversed by the operator obstructing one or more paths of the sensor array to trigger the sensor array to send said signal to said control means.

12. A system according to claim 10 or claim 11 whereupon detection by said sensor array of the presence of an article obstructing the path of the sash when the sash moves 30 from the open position, said signal is sent to said control means upon the sash being sensed within a predetermined distance of the article 23

13, A system according to any one of the preceding claims 10 to 12 wherein the first sensor array extends across the sash opening of the fume cupboard.

14. A system according to any one of claims 10 to 13 wherein the sensor array detects 5 the presence of a part of the operator.

15. A system according to claim 14 such that where the presence of a part of the operator inside the fume cupboard is not detected by the sensor array, the operator is able to trigger the sensor array to stop or reverse the direction of the sash when the sash 10 moves to within a predetermined distance of the operator.

16, A system according to any one of claims 10 to 15 further including enabling the setting of least one working height of the sash. 15

17, A system according to any one of claims 10 to 16 wherein the sensor array includes a series of substantially parallel optical beams generated by a plurality of light emitting devices and received by a corresponding plurality of light receiving devices,

18. A system according to any one of claims 10 to 17 wherein the height of the sash 20 is automatically adjusted to a height above the operator's field of movement, said field of movement being monitored prior to the adjustment of the sash height by. said sensor array.

19. A computer program for controlling a fume cupboard, the fume cupboard having 25 a sash arranged for motorised movement between a stand-by position and an open position that enables an operator access to a compartment of the fume cupboard while partly protected by the sash, whereupon movement of the sash from the open position and triggering of a sensor array, the computer program instructs a processor to: send a signal from the sensor array to a control means, and 30 reverse the direction of the sash or stop movement of the sash by sending a further signal from the control means to a sash drive means. 24

20. A method of controlling a fume cupboard substantially as hereinbefore described with reference to the accompanying drawings.

21. A system for controlling a fume cupboard substantially as hereinbefore described 5 with reference to the accompanying drawings. 25