GB2102118A - Means for detecting limited movement of mechanical devices - Google Patents

Abstract

The movement of a mechanical device such as part of a drink dispenser (optic RTM) in a path between two positions is detected without removing the device from its path by sensing electromagnetic radiation which is affected by the position of the device. There may be a plurality of sensing means and the corresponding devices, arranged in matrix formation. IR emitting diodes 4 and 6 may irradiate phototransistors 7 or 9 in dependence on the position of a plunger 11, by use of a reflective or absorptive target area 8. <IMAGE>

Description

SPECIFICATION Means for detecting limited movement of mechanical devices This invention relates to systems for detecting and monitoring limited movement of mechanical devices, for example, fluid control valves which operate on a simple open or closed basis.

A very well known example of a fluid control valve is an optic (Registered Trade Mark) which is often used to dispense a controlled quantity of spirits or fortified wine into a glass. This device consists of a glass chamber of known volume and several valves which normally permit the chamber to fill from a bottle under gravity. When a dispense from the optic is required, usually a glass is held under the optic and pushed upwards operating a sprung plunger mechanism and associated valves.

One valve closes off the intake from the bottle while an outlet valve is opened to dispense the fluid into the glass. An air bleed valve is also opened to ensure that the fluid in the chamber is quickly and completely delivered. After the chamber has emptied, the upward pressure on the glass is released so that the outlet and air bleed valves are closed and the intake valve is opened again so that the optic may refill. The emptying and refilling of an optic is made visible using a clear glass chamber so that all interested parties can verify that a correct quantity was dispensed.

The movement of the plunger required to operate the optic is typically of the order of 10 mm. In the United Kingdom (and certain other countries) there are many legal requirements relating to the design and use of optics.

Periodically it is necessary to change the bottle, this being carried out by removing the bottle and optic from a stand prior to fitting a replacement.

In order to simplify the control of stock and generate financial sales information in public houses, clubs and hotels, an automatic system which monitors the dispense of every drink is highly desirable. This information could be produced automatically and accurately requiring little effort on the part of the user. It is important, however, that the system is not costly to produce or maintain.

An object of the present invention is to provide a method of sensing or monitoring the movement and presence of a mechanical device such as a fluid control valve, of which an optic is an example, and converting such movement into an electrical signal.

The invention, in one aspect, provides a sensor device operating with electromagnetic radiation and, in another aspect, means for receiving electrical signals from a number of such devices in a matrix arrangement.

Embodiments of the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a block diagram of a system including a sensor device operating with electromagnetic radiation.

Figure 2 is a diagram of the respective positions of the elements of such a device.

Figure 3 is a simplified cross sectional view of an optic showing location of sensors in such a device.

Figure 4 is a circuit diagram of such a device.

Figure 5 is a diagram showing a system in which there is a matrix of such sensor devices..

Figure 6 is a simplified diagram showing a sensor enclosure or "shoe".

Figure 7 is a simplified diagram showing an alternative arrangement of sensors and optic in such a device.

The drawings illustrate a system for sensing the movement and presence of a mechanical device such as an optic. The system illustrated uses a microcomputer continually storing the electrical signals from sensors in a manner such that short duration electrical interference and sudden rapid actuations of the optic, which does not dispense any fluid, are ignored or recorded separately from normal actuations of the valve which normally lasts for at least a second.

Referring to fig. 1, one region or band which is reflective and one non-reflective to electromagnetic radiation is arranged to be located on a mechanical device such as a lever or an actuator 2 of which it is desired to detect the condition and presence. In its simplest form, only two conditions corresponding to, for example, valve on or valve off, are detected, together possibly with the presence of the valve. The respective orientations of the actuator, sensor assemblage and detectable movement are shown in fig. 2. Devices 4 and 5 are capable of emitting electromagnetic radiation of the desired spectrum.

In the present embodiment, devices 4 and 5 convert an electrical current into predominantly infra red light. Devices 6 and 7 are capable of detecting the electromagnetic radiation and converting it to an electrical signal which may be amplified. For infra red emission detection, a phototransistor is a suitable component which, when an appropriate voltage is applied across its terminals, passes a current related to the detected emission intensity.

Referring to fig. 2, radiation emitter 4 and detector 6 are arranged to detect the presence of the actuator 2 in either its "on" or "off" condition.

The emitter 4 and detector 6 are aligned so that the emitted radiation is only, or most effectively, detected when the actuator is not present. When the actuator is present, the beam of radiation is interrupted or absorbed by it and therefore the detector 6 generates an electrical signal equivalent to a lower level of incident radiation.

Emitter 5 and detector 7 are similar except that they are arranged so that the emitted radiation may be reflected by some part of the actuator towards the detector 7. By providing a region on the actuator which is reflective adjacent to another, which absorbs the radiation, an electrical signal may be generated which discriminates between the positions of the actuator depending on whether the "target region" 8 is reflective or absorptive.

In the present embodiment, this sensor arrangement is used to great advantage in detecting the presence and status of an optic.

There are a large number of optics in use in the United Kingdom and it is a legal requirement that they be approved and sealed by the Customs and Excise authorities (who charge for this service) prior to delivery to users such as public houses.

Furthermore, because of these legal requirements, optics from different manufacturers all tend to be very similar. Therefore, a system which is capable of monitoring the activity of the optic without necessitating dismantling or modification of internal parts of the optic in order to fit it, considerably reduces the cost of fitting such a system. Indeed, it would be practical to install such systems in the field without requiring that the optics are returned to a factory.

Referring to fig. 3, where the arrangement of the optic and sensor device is shown, emitter 4 and detector 6 are positioned such that the ray path passes through the lower part of the body of the optic 9 which is normally made of coloured piastic and thus opaque to infra red and visible light. The presence of the optic interrupts the beam between 4 and 6 and is therefore readily detected. Information about the presence or otherwise of the optic may be processed to indicate the number of bottle changes.

The normal operation of the optic, that is dispensing a measured quantity of fluid, is monitored by emitter 5, detector 7 pair. The target region 8 for this sensor pair is located on a moving part of the optic below the lower body 9. When the optic is inactive or refilling from the bottle, the target region 8 falls on item 10 which is typically a bright chrome cup which is located on the main plunger shaft 11 and used to retain a return spring 12.

When the optic is operated to dispense a measured-quantity of fluid from chamber 13, cup 10 recedes within lower body 9 and item 14 rises into the target region 8. Item 14 is normally another cup which is usually internally threaded to attach the nozzle 1 5 to the plunger 11. Although item 14 is typically bright chrome plated, it is a simple matter to cover it with a non reflective coating. By this means the condition of the optic, i.e. down (inactive or refilling) or up (dispensing) may be detected. For example, as the target region 8 changes from reflective to absorptive, the current passing through detector 7 is reduced and may be converted to a two state logic signal by additional circuitry.

On certain optic designs item 14 may be able to recede fully within the lower body 9 and hence pass the target region 8. It may then be necessary to cut away part of the lower body 9 so that the target region can be located higher in a region where cup 10 or item 14 may be at rest when plunger 11 is at either extreme of movement.

Alternatively, another cup may be attached between item 14 and nozzle 15, or a modified nozzle 1 5 fitted, so that reflective and absorptive surfaces may be moved into the target region dependinq on the position of plunger 11.

Fig. 4 shows the electronic circuitry which is used in the present embodiment to generate logic signals. These logic signals indicate whether the optic is present, that is to say in its mounting bracket, and whether the plunger 11 is up or down. In the description that follows an electrical signal name followed by a slash (e.g. SELECT/) indicates a negative logic signal which is true at low volts and false at high volts.

When monitoring the status of an optic the SELECT/ control line is arranged to be close to ground potential.

Gallium arsenide infra red emitting diodes D1 and D2 (4 and 6 in fig. 3) are wired in series with resistor R1 so that a suitable current may be passed which results in an adequate level of infra red radiation output.

The detectors 6 and 7 (fig. 3) are NPN planar phototransistors (TRl and TR2) which develop a potential difference across R3 and R2 respectively.

These potential differences are greatly amplified by transistors TR3 and TR4 so that effectively a two state output is obtained where either transistor is capable of drawing a current of in excess of 5 mA with negligible potential difference between its collector and emitter or alternatively draw a very small current ( 5 mA) for a potential difference of between say 5 and 12 volts. Diodes D3 and D4 are blocking diodes, which are used in conjunction with the SELECT/ input when the sensor device is wired together with other such sensor devices in a matrix, and are not essential to the basic operation of the circuit.

A ground connection, terminal 1 in fig. 4, is not used directly in the circuit but is provided for electrical screening purposes.

In the present embodiment of the invention it is of great advantage that the sensor devices are wired in a matrix as shown in fig. 5 for example, since this facilitates scanning of a number, typically 32 or 64, of such devices under control of a microcomputer while using the minimum number of physical wires to the sensor.

When SELECT/ is false (i.e. at + 1 2V applied to terminal 5, as well as to terminal 3) no significant current is drawn by the circuit, TR3 and TR4 are off and D3 and D4 are not forward biased. Also the BOT PRESENT signal at terminal 2 and similarly the DISPENSE/ signal at terminal 4 may be "wired OR" connected with similar signals from other sensor devices in a common group with a single pull up resistor on each line as shown in fig. 5. The state of any particular sensor device may then be determined by asserting its SELECTS line, i.e. reducing the applied voltage to near ground potential, while all others are false. In the present arrangement of the invention, it is of great advantage that many sensor devices are connected together in a matrix, since the number of signal wires required is considerably reduced, for example, 16 signal wires are required for 32 sensor devices.

A further advantage is that considerable power savings may be made since a sensor device is only drawing current when it is desired to monitor the state of its associated optic. In practice this is performed by a microcomputer which under program control periodically scans all sensor devices in the system (see fig. 5).

Fig. 6 shows a sensor enclosure or "shoe" in a self explanatory manner.

Other Possible Arrangements One possible alternative arrangement is to use a single emitter, either with or without a light pipe, arranged with the two detectors so that it performs the duties of emitters 4 and 5 together.

A second arrangement which may facilitate detection of faulty sensors is to position emitter 4 and detector 7 such that when the optic is removed part of the beam from 4 is incident on detector 7 such that both detectors 6 and 7 should be passing current. If detector 6 is passing current but detector 7 is not then detector 7 or its associated circuitry are not functioning as designed.

There are also several other possible ways of arranging the sensor device. Although it is feasible to detect the presence of the optic using an emitter and detector pair which rely on reflection of light from its body, this approach will be susceptible to interference from ambient lighting conditions etc. Another possibility is to detect dispense operations of the optic by attaching a "flag" or tab to a moving part of the optic such as items 10, 11, 14 or 1 5. This tab is arranged to interrupt or block the path of electromagnetic radiation to the detector when the plunger 11 is at one or other of its extremes of motion corresponding in one case to the optic refilling or inactive and in the other case to the optic dispensing.An example of such an arrangement is shown in fig. 7 where tab 16 is attached to cup 10 and enclosed in protective housing 1 7 which is mounted on lower body 9. The presence of the optic may conveniently be detected by the interruption of the beam of radiation between emitter 4 and detector 6 by housing 1 7. Dispense operations of the optic are monitored by emitter 5 and detector 7 which are positioned on a common axis such that the beam of radiation may pass through a suitable located window 1 8 in housing 17 and, when not interrupted by tab 16, may be transmitted without reflection directly to detector 7.Then, if for example plunger 11 is raised to perform a dispense, tab 1 6 rises into window 1 8 and interrupts the beam of radiation so that a smaller current is passed by detector 7.

Circuitry such as shown in fig. 4 and described above may then be incorporated to obtain suitable logic level signals.

A variation of this latter approach is to mount a ring having a number of tabs in a radial arrangement onto a moving part such as 10, 11, 14 or 15 so that any one of the tabs may mesh with a suitable slot in the sensor "shoe" in the manner of a gear wheel.

In order to ensure that another optic which is not suitably adapted for the sensor device is not inadvertantly inserted in the stand, a keyway 20 may be cut into the mounting flange 19 of the required optics and a corresponding obstruction placed in the optic clamp (not shown). This keying system may be increased in complexity so that different sizes of optics may only be mounted in appropriately keyed clamps, this keying being performed by a plurality of keyways perhaps of different depths and shapes.

Further Advantages of the System a) The method of detection is not visible or obvious and is therefore not readily interferred with by unscrupulous users.

b) In operation, the system is not sensitive to ambient light levels for the following reasons: i) When the optic is removed and the sensors are most exposed to ambient light, detector 6 is irradiated by emitter 4 and the signals obtained from detector 7 (which normally monitors dispenses) can be disregarded.

ii) When the optic is in place a "sensor shoe" shown in fig. 6 which contains the sensor electronics together with the optic body itself may be arranged to more than adequately screen the detectors 6 and 7 from stray radiation.

c) Under normal conditions a signal is always obtained from the sensor device associated with a particular optic except during the time when a dispense is in process. During this time the same logic conditions could be obtained if the sensor device were not present. However, since a dispense operation normally takes of the order of a few seconds and cannot be repeated until the optic has refilled (lasting perhaps a second), the microcomputer may be readily programmed to discriminate between loss of signal for long periods (i.e. sensor device faulty or not fitted) and normal dispense operations. In the preferred embodiment the microcomputer scans each sensor device several times a second and may also be programmed to distinguish between noise pulses or other abnormal events which last perhaps only one scan and normal dispense or bottle change operations which will take several seconds to be completed.

Claims (6)

1. A method of detecting limited movement of a mechanical device between first and second positions with or without also detecting removal of the device from the place in which the detection of the limited movement occurs, which method involves the emission of electromagnetic radiation towards the device and the sensing of alternative levels of such radiation corresponding to the condition of respective surfaces of the device or of an attachment which moves with the device, or to the presence and absence respectively ofsuch surface, in the path of the electromagnetic radiation, which emission and sensing may be carried out repetitively and may be effected sequentially in respect of a number of such mechanical devices with the emission and sensing means preferably in a matrix arrangement.

2. A method according to claim 1, using infra red light as the said radiation.

3. A method of detecting limited movement of a mechanical device between first and second positions with or without also detecting removal of the device from the place in which the detection of the limited movement occurs, the method being substantially as herein described with reference to the accompanying drawings.

4. A method according to claim 1 2 or 3, applied to an optic for dispensing spirits or other liquid.

5. A sensor device substantially as herein described with reference to the accompanying drawings.

6. Means for receiving electrical signals from a number of sensor devices in a matrix arrangement, substantially as herein described with reference to fig. 5 of the drawings.