AU8157087A - Drying apparatus - Google Patents

Description

DRYING APPARATUS

The present invention relates to drying apparatus, for example for drying hands and other parts of the body with the aid of warm air. Previously proposed warm air drying apparatus for drying hands includes an electrically- operated blower and a heating element which together are arranged to produce a flow of heated air through an outlet. The outlet directs the flow of air over the user's hands to effect a drying action. A manually operated switch is provided to energise the blower and heating element when it is desired to use the apparatus. However, manually-operated switches are generally undesirable as they may be left in an ON state inadvertently when the user has finished with the apparatus, thereby wasting energy. In order to overcome this problem, it has also been proposed to provide a timing arrangement so that following manual operation of the switch, the blower and heating element are energised only for a predetermined period of time. However, if the user requires a longer time than that predetermined period for drying his hands, it then becomes necessary for the user manually to operate the switch once again at the end of the predetermined period and this has been found to be inconvenient to the user. Furthermore, the user may not require the apparatus to operate for the full predetermined period of time or multiples of that period to dry his hands and in this case energy is wasted unnecessarily. Such an arrangement is therefore considered unsatisfactory.

Instead of a manually operated switch it has also been proposed to provide photo-electric, ultrasonic or capacitive sensors for detecting the proximity of a part of the user for example the hands. The blower and heating element are energised when proximity is detected. However, such sensors rely for their operation on comparing the sensed signal with a predetermined threshold level when the user's hands are sufficiently close to the sensor. It is common practice to provide means for manually adjusting the signal threshold level inside the apparatus to compensate for different site conditions, e.g. capacitive sensors are affected by the proximity large earth masses. Reflective light sensors are affected by proximity of reflecting surfaces and ambient lighting. Any such adjustments will adversely affect the sensitivity of the device. Furthermore, any subsequent change in the ambient conditions may cause the device to be activated continuously thus waste energy.

It has also been proposed to include a movable air flow nozzle or an air flow directing flap over the outlet. Such a flap is manually movable between two positions, to direct a warm air flow produced by a fan and heater combination either onto the hands or onto the face of a user. Photo-electri c sensors have also been used to sense the movement of the flap from the hand directed position to the face directed position and to energise the fan and heating element in response to such a change in positions. Such apparatus is disclosed in UK Patent Specification No.2, 136.291. However, the use of such sensors has also proved unsatisfactory in that if the flap is jammed in the face directing position by vandals this causes the apparatus to be activated continuously.

It is an object of the present invention to provide an improved air drying apparatus. According to the present invention there is provided drying apparatus comprising air supply means operable to provide a flow of air from an outlet, flap means movable to direct the air from the outlet selectively in one of two directions, sensing means responsive to the presence of an object in said one direction to actuate said air supply means and response to the removal of said object from one said direction to deactuate the air supply means.

Advantageously said object is the hand of a user which becomes positioned into said one direction as a result of moving said flap means from a position in which directs air from said one direction to said other direction.

According to the present invention there is further provided drying apparatus comprising air supply means operable to provide a flow of air from an outlet, flap means movable to direct air from the outlet selectively in one of two directions, detection means for detecting the entry of an object into a predetermined monitoring area, said predetermined monitoring area being in said one direction when the flap means is positioned to direct air in one said direction and being on the other one of said direction when the flap means is positioned to direct air in said other direction.

Preferably the flap means includes deflection means for deflecting the predetermined area from said one direction to said other direction when the flap means is moved to direct said air flow from said one direction to said other direction.

Advantageously the apparatus includes inhibiting means for inhibiting the operation of the detection means while the flap is moved to change the air flow direction. Preferably the detection means includes a control circuit comprising an input for receiving an input signal indicative of the movement of an object In said predetermined monitoring area, first and second paths connecting said input terminal to respective ones of two inputs of a comparator, one said path including a first bidirectional delay circuit which is capable of delaying a rising signal appearing at the input for a substantially longer period than a falling signal, a second bidirectional delay circuit connected to the output of the comparator, and switch means responsive to the output of the second bidirectional delay circuit to control the air supply means.

Advantageously the ratio of the two delays of the first bidirectional delay means is greater than 25:1.

Warm air drying apparatus embodying the Invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings in which:

Figure 1 is a fragmentary side elevation of a first embodiment of the apparatus;

Figure 2 is a fragmentary side elevation of a second embodiment of the apparatus; Figure 3 is a block diagram of a control circuit for the apparatus of Figure 1 or Figure 2; and

Figure 4 is a circuit diagram of the control circuit of Figure 3. As shown in Figure 1 the warm air drying apparatus includes a casing 9 housing an electric fan 2, a manifold 4 for directing air from the fan 2 to an outlet cavity 6 in the casing 9 and an electrical heater 8 located in the manifold 4 to heat the air before it reaches the outlet cavity 6. A movable flap 10 is located in the outlet cavity 6. The flap 10 is held between a pair of generally triangular shaped side plates 12 which in turn are pivotally supported in the cavity 6 to allow the flap 10 to be pivoted between a generally vertical position (as shown in solid lines) which causes air flow from the cavity to be directed downwardly, and onto a hand 14 of a user located below the cavity 6, and a generally horizontal position (as shown in broken lines) which causes air flow from the cavity 6 to be directed horizontally or even slightly upwardly towards the face (not shown) of the user.

A spring (not shown) normally biases the flap 10 into the generally vertical position shown in solid lines.

In operation the user dries his hands by positioning them directly below the cavity 6, and dries his face by engaging 'the flap 10, when in the vertical position, with his hand and displacing the flap into the horizontal position by moving the hand 14 into the position shown in Figure 1.

The flap 10, when in the vertical position, lies flush with, or is recessed inwardly of a vertical wall of the casing 9 so that the user cannot grip the upper portion of the flap 10 but is obliged during the opening operation to move the hand into a position below the cavity 6.

An infra-red detector 16 is located in the bottom portion of the cavity 6 and has a monitoring sector 18 which lies directly below the cavity 6. The upper extremity of the sector 18 is positioned just below the locus of the flap so that the flap does not enter the sector when being moved from its verti cal to its horizontal position. The upper extremity of the sector 18 is, however, located sufficiently close to the locus of the flap to ensure that the hand 14 enters the sector 18 when moving the flap from the vertical to the horizontal position.

The infra-red detector 16 is in the form of an infra-red transmitter which transmits infra-red light into the area covered by the sector 18 and an infra-red receiver which receives any Infra-red light reflected back to the detector by the presence of an object in the sector 18.

A control circuit to be described in more detail hereinafter responds to the detector to energise the fan 2 and the heater 8 when the presense of a hand in the sector 18 is detected. Thus when the flap 10 is in the vertical position and a hand is placed in the sector 18, the presence of the hand is detected by the detector 16 which will cause warm air to be directed on the hand to effect drying of the hand. When a hand engages the. flap 10 and moves it from the vertical to the horizontal position, the hand upon entering the sector 18 will again be detected by the detector 16 and this time a stream of warm air will be directed horizontally at the face of the user. As soon as the hand 14 is removed from the sector the detector 16 will cause the supply of warm air to be cut off.

Warm air is thus supplied to the hand or the face only on demand. In the warm air drying apparatus shown in

Figure 2 parts similar to those in Figure 1 are simllarily referenced. Also the fan 2, the manifold 4 and the heater 8 have been omitted for the sake of clarity. The flap 10 is provided with a mirror 20 or a reflective surface on its rear face, and the detector 16 is positioned to lie above the flap 10 when in the horizontal position. The detector 10 is so positioned that when the flap 10 is in the vertical position it has a monitoring sector 22 directed downwardly of the cavity 6 and when the flap 10 is the horizontal position the sector 22 is interrupted by the mirror 20 and so the monitoring sector is displaced to define a sector 24 (shown in solid lines) which is directed generally horizontally and upwardly of the cavity 6.

In operation when the flap 10 is in the horizontal position, the detector 16 will detect a face entering the sector 24 and cause warm air to be directed onto the face. When the face moves out of the sector 24 the detector 16 will cause the supply of warm air to be cut off.

When the flap 10 is in the vertical position the detector 16 will detect a hand entering the sector 22 and will cause warm air to be directed onto the hand. When the hand moves out of the sector 22, the detectors 16 will cause the supply of warm air to cease.

A pair of microswitches 28 and 26 are provided to detect when the flap 10 is respectively in the horizontal and vertical positions. The microswitches inhibit the operation of the detector 16 while the flap is between the vertical and horizontal positions so that the movement of the flap should not trigger the detector 16.

In one form the switches are connected in parallel and the parallel combination is connected in series with the power supply path to the detector 16. Each switch is only closed when the flap is in its corresponding vertical or horizontal position. Thus it will be seen that the detector is effectively switched OFF when the flap is being moved between its horizontal and vertical positions and is only switched ON again when the flap reaches its vertical or horizontal position.

Each switch 26 and 28 can take the form of a reed switch, a capacitive switch or a microswitch.

With this embodiment the positioning of the detector 16 is within the locus of the flap 10 so making It less vulnerable to vandalisation.

Advantageously the microswitch 28 when switched on also is connected to increase the range of the infrared transmitter. For example with the flap vertical, the transmitter when detecting a hand has a range of from 15 to 20 cm but with the flap horizontal and triggered by the switch 28 to detect a face, the transmitter has a range of from 30 to 40 cm.

In a modification, instead of two switches, a single switch and cam (not shown) can be used. The cam is coupled to the flap and engages the microswitch so that the microswitch Is only switched on when the flap is In one of its two extreme positions. Figure 3 shows the control circuit for controlling the fan 2 and the heater 8 in response to the detector 16.

As shown the detector includes a transmitter 30 and a receiver 32 which receives transmitted signals reflected from an object being detected. The output of the receiver 32 is connected to one input of a comparator 36 via a variable resistor 34 and to the other input of the comparator via a bidirectional time delay circuit 38. The delay circuit 38 includes a resistor 42 and capacitor 44 connected in series with the junction between the capacitor 44 and resistor 42 connected to the input of the comparator 36. A diode 40 is connected in parallel with the resistor 42. The delay circuit 15 is so conditioned that it can delay the arrival of a rising signal from the receiver t o the second input of the comparator 36 by for. example 1 minute but the delay provided to a falling signal would be say 250 ms. The arrangement is such that the capacitor

44 in effect always stores the minimum signal which it applies to the second input of the comparator 36.

It will be appreciated that the control circuit continually compensates for changing ambient conditions. If a hand were placed in the monitoring sector of the detector and held completely stationary the comparator 15 would intially generate an output but eventually the signal passed by the delay circuit 38 to the comparator 36 would rise and the comparator 36 would switch OFF.

In actual practice the hand is infact always moving and so there will be periodic rising signals generated by the receiver 32 and fed to the comparator 36. This does of course mean that the comparator 36 does periodically switch OFF while the hand is present in the monitoring section. To prevent this periodic interruption from effecting the operation of the fan and the heater the output of the comparator 36 is fed through another bidirectional time delay circuit 38 and a zero voltage switch 40 before being fed to the heater 2 and the fan 8. _.The effect of the delay circuit 38 is to sustain an output signal for the switch 40 during the short periods over which the output from the receiver 32 is falling. If the output of the receiver 32 falls over a longer period such, as would occur if the hand were completely withdrawn from the montoring sector then the output signal from. the delay circut 38 would eventually cease and the switch 40 would de-energise the fan 2 and the heater 8.

It will be appreciated that with the control circuit shown, the circuit is able to distinguish between a hand or face requiring drying (and which is constantly moving) and a vandalised condition when, for example, paper or other matter has been jammed in the outlet cavity 6 (an immobile situation). With the former situation the fan and heater are kept in continuous opertion while with the latter situation the fan and heater are quickly deenergised and a hazardous situation is avoided.

Further more as soon as the jammed paper or other matter has been removed, the control circuit will immediately resume operation without the need for resetting or replacing fuses. The actual circuit diagram of the block diagram of Figure 3 is shown in Figure 4.

Claims (1)

1. 1. Drying apparatus comprising air supply means operable to provide a flow of air from an outlet, flap means movable to direct air from the outlet selectively in one of two directions, detection means for detecting the entry of an object into a predetermined monitoring area, said predetermined monitoring area being in the path of said said one direction when the flap means is positioned to direct air in one said direction and being in the path of the other direction when the flap means is positioned to direct air in said other direction.

   2. Apparatus according to Claim 1 wherein the flap means includes deflection means for deflecting the predetermined monitoring area from said one direction to said other direction when the flap means is moved to direct said air flow from said one direction to said other direction. 3. Apparatus according to Claim 2 wherein said deflection means comprises a mirror secured to an internal face of the flap means.

   4. Apparatus according to any preceding claim including inhibiting means for inhibiting the operation of the detection means while the flap is being moved to change the air flow direction. 5. Apparatus according to any preceding claim wherein the detection means comprises an infrared detector. 6. Apparatus according to any preceding claim wherein said detection means comprises a control circuit comprising an input for receiving an input signal indicative of the movement of an object in said predetermined monitoring area, first and second paths connecting said input terminal to respective ones of two inputs of a comparator, one said path including a first bidirectional delay circuit which is capable of delaying a rising signal appearing at the input for a substantially longer period than a falling signal, a second bidirectional delay circuit connected to the output of the comparator, and switch means responsive to the output of the second bidirectional delay circuit to control the air supply means. 7. Apparatus according to Claim 6 wherein the ratio of the two delays of the first bidirectional delay means is greater than 25:1.

   9. Drying apparatus comprising air supply means operable to provide a flow of air from an outlet, flap means movable to direct the air from the outlet selectively in one of two directions, sensing means responsive to the presence of an object in said one direction to actuate said air supply means and responsive to the removal of said object from one said direction to deactuate the air supply means .

   10. Apparatus according to Claim 9 wherein said object is the hand of a user which becomes positioned in the path of said one direction as a result of moving said flap means from a position in which directs air from said one direction to said other direction.

   11. Warm air drying apparatus substantially as hereinbefore described with reference to the accompanying drawings.