This invention relates to a vending machine, and more
particularly to a vending machine of the type typically required
for occasional use, such as are used to dispense packets of items
such as condoms or sanitary towels.
The type of vending machine at which the invention is
directed is often located in remote areas where there may be no
ready access to a mains electricity supply. A machine which is
electrically operated, as opposed to a mechanical configuration,
therefore requires a battery. Accordingly, the power consumption
of the machine should be minimised.
The machines may also be required to offer a wide range of
products whilst occupying a limited volume as they are often
situated in areas where space is restricted.
Packets are commonly held in such vending machines in a few
vertical stacks. When the machine is operated the lowermost
packet in a stack is pulled out from the pile and dispensed to
the user. The packets remaining in the stack then fall under
gravity to occupy the space left by the dispensed packet.
However, the weight of the stack means that the packet at the
base thereof may be damaged and a considerable force is necessary
to remove it when the stack is substantially full. Accordingly,
a significant amount of energy is used to provide the requisite
force. Also if a machine is to offer several different products,
the width of the machine becomes substantial.
The present invention provides a vending machine comprising
a housing, control and money handling means for receiving cash
or tokens and initiating the release of a selected item, and a
plurality of substantially horizontal supports mounted within the
housing, each adapted to carry a horizontally disposed stack of
items to be dispensed one by one, and having means for urging a
respective stack against an abutment at one end thereof, which
end is adjacent a channel down which a dispensed item falls and
which leads to an outlet of the machine, guide means for
retaining all but the next-to-be-dispensed item in line with the
stack, and a paddle capable of rotating through a position where
it engages the next-to-be-dispensed item, and pushing it out of
line with the rest of the stack past the abutment so that it
falls into the channel. A sensor may be provided at the one end
of each horizontal support, which sensor is adapted to detect the
presence or absence of a next-to-be-dispensed item thereagainst,
and output a signal indicating said presence or absence to the
control means.
As a substantial force is not required to retain the items
aligned in a horizontal stack, the force applied by the paddle
to the end packet does not need to be large to push it out of
line with the rest of the stack. Accordingly, a relatively small
amount of energy is required. The use of a rotary paddle
arrangement, which is preferably mounted adjacent each shelf,
also minimises the energy used in each vending operation.
The apparatus of the invention is also advantageous as each
paddle does not need to be maintained in contact with a
respective stack all the time and only a single item needs to be
moved in the vending operation by means of energy from the power
source of the apparatus.
An embodiment of the invention will now be described by way
of example and with reference to the accompanying drawings
wherein:
Figure 1 is a perspective view of a vending machine
according to the invention; Figure 2 is a perspective view of a dispensing mechanism for
adoption in the vending machine of Figure 1; Figure 3 is a perspective view of the dispensing mechanism
of Figure 2, showing an intermediate position in the dispensing
operation; Figure 4 is a flow chart representing a method of operation
of the vending machine of Figure 1.
The vending machine illustrated in Figure 1 comprises a
housing 2 with a door 4. The door can be securely locked to the
body of the housing. The machine contains several horizontal
supports or shelves 6. The products 8 are biased towards the
right hand side of the machine (in the orientation shown in the
Figure) by sliding blocks 10. An electronic coin handling and
control unit 12 is disposed on the inner surface of the door 4.
The location of a shallow unit in this position maximises the
volume available in the housing 2 for holding products. A
selection and display panel is provided on the outer surface of
the door 4.
The unit 12 can be entirely conventional and so will not be
described here in detail. Inserted coins are checked for
validity and value. Accepted coins are retained and their
accumulated value stored, whilst invalid coins are returned to
the user. Once sufficient value has accumulated, the unit 12
will allow the dispensation of a product to be initiated.
The user makes a selection via the unit 12, and if
available, a corresponding product 8 is released from the right
hand end of the appropriate shelf 6 by a dispensing mechanism
(described below). The product then falls down a vertical
channel 14, past a tamper prevention flap 16 into a chamber 18.
It may then be removed by the user through an aperture in the
door 4 after pushing back the flap 20. The flaps 16 and 20 are
arranged so that when the flap 20 is pushed back, it is not
possible to reach past the flap 16. The shelves 6 are mounted
within the housing 2 in such a manner that their height may be
adjusted in small increments so that a wide range of packets can
be accommodated. It also allows a number of shelves to be
adjusted to hold the same product, or each hold a different sized
packet, for example. Packets are arranged on the shelves with
their shortest dimension along the line of the shelf to maximise
the number of packets that may be stored on each shelf.
An upstanding lip 21 is provided along the front edge of
each shelf to align the products. Its position across the shelf
may also be adjusted to accommodate different sizes of packet.
In addition, an upstanding tab 22 is provided at the end of
each lip 21 near the right hand end of the shelf. Its location
along the shelf relative to the lip is adjustable according to
the width of the packets, so that only the end packet is able to
move outwardly from the back wall of the housing. In other
words, only a single packet can be dispensed at a time from a
shelf because the others are held by the lip 21 and tab 22.
If small packets are to be dispensed, the shelves may be
configured to hold two parallel rows of packets, one behind the
other, which can be released into the channel 14 under the
control of the unit 12.
The number of types of product that the machine could
handle, may be substantially increased by providing the vertical
channel 14 centrally within the housing 2. Thus products may be
dispensed into the channel from either side.
An embodiment of a dispensing mechanism in accordance with
the invention is shown in Figure 2. Such a mechanism is disposed
at one end of each shelf in the vending machine. Three packets
8 are represented by dashed lines in the Figure.
In the illustrated orientation of the arrangement, the block
10 is urged from left to right by a known constant force spring
24. The block is slidably mounted against the bracket 16 by
means of a "dovetail" type engagement. It is able to move
smoothly along the bracket whilst accurately held with its
pushing surface perpendicular to the direction of sliding.
An abutment 28 is disposed at the right hand edge of the
shelf 6. Thus the packets 8 are urged with a constant pressure
against the abutment by the block 10, and are confined in a
horizontal stack therebetween. The surface provided by the
abutment for engaging the end packet of the stack is flat to
ensure that the end packet is held in alignment with the rest of
the stack, even though it does not contact the lip 21 or the tab
22. A microswitch 25 is mounted on this surface, the operation
of which is discussed below. The longitudinal position of the
abutment with respect to the shelf is adjustable by temporarily
loosening a screw 27, which passes through a slot 29 in the
abutment. Its position may be adjusted, together with that of
the tab 22 to ensure only a single packet is dispensed at a time.
A paddle assembly 30 is rotatably mounted adjacent to the
end of the shelf 6. It is driven, under the control of the unit
12, by an electric motor 31 via a reduction gear box 33. The
paddle configuration shown in Figure 2 has two fingers 32 and 34
(dotted) which pass through the slots 36 in the bracket 26, and
above and below the abutment 28, respectively, when the paddle
is rotated in the direction of arrow A. A product is dispensed
from the shelf by rotating the paddle through one complete turn
in this direction, and an intermediate position is shown in
Figure 3.
After the fingers 32 and 34 pass through the slots 36, they
engage the rear surface of the packet at the end of the shelf,
and then push it forwards, away from the bracket 26. As the
paddle 30 continues to rotate, it pushes the packet past the
abutment 28. The horizontal stack can then advance along the
shelf, pushing the end pack over the right hand edge of the
shelf. It then falls down the vertical channel 14 as discussed
above.
The products likely to be dispensed from this machine are
light and supplied in rigid packets. Therefore, the tension in
the spring 24 need not be great to retain the packets on the
shelf, and as a consequence of these factors, the power required
by the paddle is not large. The upper surfaces of the shelves
are preferably designed to be smooth and to minimise any friction
with the products. In addition to minimising the energy
consumption of the dispensing mechanism, these considerations
also reduce the likelihood of any products being damaged.
Although the paddle is shown with two fingers 32 and 34 in
Figure 2, other configurations may be adopted as appropriate.
The fingers are illustrated as being slightly curved and this
shape has been found to be advantageous and to dispense the
packets in a predictable manner.
The microswitch 25 provided on the abutment 28 is biased
towards the raised position shown in Figure 3. The contacts of
the microswitch are either open or closed when it is in the
raised position, and are in the opposite state when the switch
is depressed. When one or more packets 8 are present on the
shelf 6, the microswitch is depressed by the end packet as shown
in Figure 2. If a packet is pushed off the end of the shelf 6,
the switch briefly moves to the raised position, until the next
packet in the stack is pushed thereagainst by the block 10. This
brief switching of the microswitch is detected by the control
unit 12 to confirm that a packet has been successfully released
from the shelf. Energisation of the respective motor 31 is
stimulated by the control unit for a predetermined period of time
after the detection of the switching signal to rotate the paddle
30 to a predetermined position clear of the space above the shelf
6.
If there are no packets on a shelf, the block 10 is held
near the end of the shelf against a stop (not shown) by its
spring 24. The stop is positioned such that the block is spaced
from the microswitch 25 in its raised position. Accordingly, if
a microswitch is constantly in the raised position, the control
unit 12 can determine that the corresponding shelf is empty. If
another shelf holds a stack of the same product, the unit 12 then
checks the corresponding microswitch. Otherwise, the unit
informs the user the product is not available via the display
panel and awaits further input, such as a refund request, further
cash or selection of another product. If there is no input after
a predetermined time, say fifteen seconds, then the user's cash
is automatically refunded.
In an alternative embodiment of the invention to the
microswitch-based configuration, a detector 38 (see Figure 1) is
provided near the foot of the channel 14, below the lowermost
shelf, to sense when a packet passes through the channel. When
a user requests a particular product, the respective motor 31 is
activated, and the corresponding paddle rotates dislodging a
packet into the channel 14. If the detector senses that a packet
has been dispensed, it initiates the stopping of the active
motor. It is preferable for the paddle to return to its initial
position, as shown in Figure 2, for example. The packets take
different times to fall from different shelves to the height of
the detector. The paddle may therefore be rotated to its
original position by operating the motor for a predetermined time
following the detection of a packet, taking into account the time
taken for the packet to fall from a given shelf. If a packet is
not sensed by the detector after a certain period of motor
operation, two seconds for example, then this indicates that the
particular shelf is empty.
An advantage of this arrangement is that the overall control
can be relatively simple. Thus it does not have to sense
directly whether there is stock available. It does this by
waiting to see if an item is dispensed down the channel. Also
the functioning of the paddles does not have to be highly
accurate; it is sufficient for them to make at least one
approximately complete revolution.
Figure 4 is a flow chart representing a preferred sequence
of operation of a dispensing machine of the invention
incorporating the microswitch-based control system. The use of
an electronic control unit allows such a sequence to be readily
altered as appropriate, whilst also requiring minimal power in
operation.