[0001] The present invention relates to a mail sorting device.
[0002] Devices for sorting flat, rectangular mail items (letters, postcards, documents,
magazines, etc.) are known comprising:
- a mail receiving and singling module, which receives packs (stacks) of flat, rectangular
mail items, and feeds out single, i.e. physically separate, mail items spaced a minimum
distance apart; and
- a sorting module, which is input-connected to an output of the receiving and singling
module and, by means of deflectors, directs each incoming single mail item to one
of a number of accumulating devices of the sorting module.
[0003] Each accumulating device is normally associated with one or a number of postal destinations.
[0004] Each mail item is directed to an accumulating device on the basis of data (e.g. a
printed bar code and/or receiver data) on the mail item.
[0005] The sorted mail is accumulated in the accumulating devices in the form of respective
packs; and, when the size of the pack exceeds the maximum capacity of the accumulating
device, the sorting device is forced to direct the mail elsewhere, thus increasing
operating cost.
[0006] That is, the pack must be physically removed from the accumulating device and placed
inside one or more containers. When full, each container is tagged with a tag bearing
a serial identification bar code and the next destination, and is sent either for
further processing or to the output of the system.
[0007] The capacity of the containers normally differs from (e.g. is roughly 75% of) that
of the respective accumulating device.
[0008] To avoid reaching the full capacity of the accumulating devices, the operator in
charge of emptying the accumulating devices normally : checks fill-up of the accumulating
devices; selects the fullest accumulating device at any given time; approaches the
device; removes one or more handfuls of mail; and places the mail inside a relative
container next to the accumulating device.
[0009] The full level of known accumulating devices is determined by a sensor, which detects
the end position of a retaining device or separating slat retaining the front face
of the pack.
[0010] In known devices, an almost- or half-full level is also indicated by a sensor, which
determines the position of the retaining device (separating slat) with respect to
its end position.
[0011] The half-full indication enables more effective preventive intervention by the operator
than the full-level.
[0012] The full and half-full levels are normally indicated by steady or flashing lights
to draw the operator's attention to the full or half-full device.
[0013] Computer machine control systems are known which, for each mail item loaded into
the device and bearing a machine-readable identification code (ID-tag), record :
- the date and time the item was loaded;
- the identification code (scanned or newly printed ID-tag);
- the postal destination;
- the accumulating device the item was directed to;
- general data relating to processing or the mail stream of the item.
[0014] Known computer systems of known sorting devices employing accumulating devices of
the type described fail to associate an item directed to a given accumulating device
with the container used to empty the accumulating device and for transfer to further
processing or to the output of the system.
[0015] This is due to the different size and capacity of the accumulating device with respect
to the containers, and hence the way in which the device must be emptied. That is,
systematically waiting for the device to fill up completely would result in additional
cost and work to reload the items that could not be loaded into the full accumulating
device during sorting.
[0016] It is an object of the present invention to provide a mail sorting device which determines
the fill level of each accumulating device as a function of the number and size of
the mail items fed into the accumulating device, and which, by means of a manual emptying
procedure into one or more containers, provides for accurately associating a list
of the mail identification codes (ID-tags) with the identification code on the container
tag.
[0017] According to the present invention, there is provided a mail sorting device comprising
a mail receiving and singling module which receives packs of mail items and feeds
out single, i.e. physically separate, mail items; and a sorting module input-connected
to an output of the receiving and singling module, and which directs each incoming
single mail item to a selected accumulating device forming part of a number of accumulating
devices of the sorting module; the sorting device being
characterized by comprising a measuring device located upstream from the sorting module to determine at least
one dimensional parameter of the single mail item fed to said sorting module; the
dimensional parameter information being associated with an indicator of the selected
accumulating device to perform a procedure by which to determine the fill level of
the accumulating device as a function of the number and size of the mail items fed
to the accumulating device.
[0018] A preferred embodiment of the invention will be described with reference to the accompanying
drawings, in which:
Figure 1 shows a schematic of a sorting device in accordance with the teachings of
the present invention;
Figure 2 shows a portion of the Figure 1 device in more detail;
Figure 3 shows a detail of Figure 1.
[0019] Number 1 in Figure 1 indicates as a whole a mail sorting device in accordance with
the teachings of the present invention.
[0020] Device 1 comprises a known mail receiving and singling module 3 (therefore not described
in detail) which receives parallelepiped-shaped packs 4 (not shown to scale) of flat,
rectangular mail items 7 (letters, postcards, documents, etc.), and feeds out single,
i.e. physically separate, mail items.
[0021] Mail receiving and singling module 3 comprises a first known reading device 8a for
recognizing a unique ID-TAG (e.g. a bar code) on each single mail item 7. The information
acquired from the unique ID-TAG is transmitted to an electronic control unit 9 of
device 1. Reading device 8a may be associated with a known second reading device 8b
for conveniently acquiring a two-dimensional (grey-level, colour or binary) image
I
PO of mail item 7; which image I
PO may be processed by automatic coding (OCR) systems of control unit 9, or by manual
coding (VCD) systems for reading the address on mail item 7. If the mail item originally
has no ID-TAG, one may be printed by a printer (not shown) activated after the image
is processed. In which case, the on-line printed ID-TAG is read by another reading
device (not shown) identical to reading device 8a and downstream from the printer.
[0022] Device 1 also comprises a sorting module 11 (shown schematically) input-connected
to an output of receiving and singling module 3, and which directs each incoming single
mail item 7 to one of a number of accumulating devices 12 of module 11. Each accumulating
device 12 is typically associated with one or a number of postal destinations.
[0023] For example, twenty adjacent accumulating devices 12 are provided, each associated
with a respective logic output indicator E1, E2, ..., En, E20.
[0024] The output is typically selected by unit 9 by means of known sorting programs employing
the information in the two-dimensional image I
PO of the mail item and/or on the ID-TAG to select a logic output indicator E1, E2,
..., En, E20.
[0025] According to the present invention, a measuring device 15 upstream from sorting module
11 determines at least one dimensional parameter of the single mail item fed to sorting
module 11. Measuring device 15 conveniently determines at least the thickness of a
mail item 7, though the length and width of mail item 7 may also be determined.
[0026] The dimensional parameter information is associated, at electronic control unit 9
level, with the selected accumulating device indicator (E1, E2, ..., En, E20) in the
course of a procedure (described in detail below) for real-time determining the fill
level of each accumulating device 12 as a function of the number and size of mail
items 7 fed to the selected accumulating device.
[0027] Figure 2 shows part of device 1 in more detail.
[0028] More specifically, module 3 comprises a push device (separating slat) 17 movable
along a straight runner 18 to push pack 4, resting on a flat supporting wall 19, onto
a locating wall 20 fitted with two rollers 21, which withdraw the leading item in
pack 4 facing wall 20, so mail items 7 are removed one at a time (i.e. singled out)
from pack 4.
[0029] The single mail items 7 are fed to the input of a known conveying system 22 (shown
schematically), in which a straight conveyor belt 23, extending between end pulleys
21 and 24, feeds mail items 7, positioned substantially vertically, along a straight
path.
[0030] First and second reading devices 8a, 8b are located along conveying system 22 and
positioned facing belt 23.
[0031] Thickness measuring device 15 comprises a first locator (roller 26) defining a supporting
position for an inner portion of belt 23; and a second locator (roller 27) located
on the opposite side of belt 23 to roller 26 and having elastic means 28 for pressing
roller 27 onto a flat outer portion of belt 23. Roller 27 is associated with a position
sensor 29 for measuring displacement of roller 27 with respect to the supporting position
and therefore the thickness dc (dimensional parameter) of the mail item resting on
belt 23 and interposed between belt 23 and roller 27.
[0032] Thickness dc is measured with mail item 7 compressed between rollers 26 and 27 by
elastic means 28.
[0033] The analog signal produced by position sensor 29 is first digitized by an A/D converter
30 and then sent to unit 9, which thus knows the thickness of each mail item travelling
along the conveying system.
[0034] Downstream from rollers 26 and 27, which compress the mail item by exerting pressure
on its opposite faces, the mail item may expand (as shown schematically by mail item
7 at the end of belt 23) to an unconfined thickness de greater than the measured thickness,
i.e. (de>dc).
[0035] In the case of a letter, for example, expansion of mail item 7 is caused by the intrinsic
resilience of the folded sheets inside the envelope of the letter.
[0036] The other dimensions (width and height) of the mail item are determined by photocells
(not shown) in known manner.
[0037] Accumulating devices 12 are selected by known deflectors 31 (Figure 3) controlled
by electronic control unit 9, communicating with conveying system 22, and movable
between a rest position (not shown in Figure 3) in which they have no effect on the
mail items travelling along conveying system 22, and an intercept position (shown
in Figure 3) in which mail items 7 impinge on and are diverted by deflector 31 to
the input of accumulating device 12.
[0038] Accumulating device 12 comprises an elongated accumulating bin 32, into which the
mail items are fed successively to form a pack 4b of mail items in a direction D parallel
to the lengthwise extension of accumulating bin 32.
[0039] Accumulating bin 32 is bounded by a flat, rectangular bottom wall 33 and two lateral
walls 34. A slat 35 has an end portion that slides along a straight runner 37 fitted
to a lateral wall 34. Slat 35 extends crosswise to straight runner 37, is perpendicular
to bottom wall 33, and so forms a stop for a first face of pack 4b, a second face
of which is defined by the last mail item 7 fed into accumulating bin 32. As mail
items are fed into bin 32, the size (length L) of pack 4b increases in direction D
and moves slat 35 towards a front end portion 32a of bottom wall 33.
[0040] Accumulating devices 12 are shown coplanar in Figure 1 for the sake of simplicity,
but may lie in different, e.g. two or four superimposed, planes.
[0041] Accumulating device 12 may differ from the one shown in Figure 3 and comprise, for
example, a bin (not shown) for accumulating mail items vertically one on top of the
other. Such bins are normally arranged in a matrix structure.
[0042] As described below, packs 4b may be removed from the accumulating devices (the accumulating
devices may be emptied) either manually by an operator OP (Figures 1 and 3) or by
a known robot device (not shown) for transferring a group of mail items from an accumulating
device to a container.
[0043] Each accumulating device 12 is associated with a printer 40 (Figure 3) for printing
tags 41, and which interfaces with electronic control unit 9 and is activated by the
operator pressing a button 42.
[0044] More specifically, electronic control unit 9 controls printer 40 to perform the following
function :
- if button 42 is pressed when accumulating device 12 is empty, no tags 41 are produced;
- if button 42 is pressed when accumulating device 12 contains mail items, a tag 41
is produced, on which are printed the destination of the mail items in pack 4b, an
identification code of pack 4b of mail items 7 in the form of a bar code, processing
and system information, and the date and time the tag was printed.
[0045] For each accumulating device 12, electronic control unit 9 receives the following
data :
- a) the number of mail items fed into the accumulating device;
- b) the dimensional data (minimum thickness dc and possibly also the height and width)
of each flat mail item 7.
[0046] From the sequentially acquired thickness data, the instantaneous length of the pack
of compressed mail items is calculated by adding the thicknesses of the mail items
travelling through thickness measuring device 15, i.e. compressed pack length Lc =
sum of thicknesses dc
[0047] Length Lc is calculated assuming all the mail items in the pack are compressed, i.e.
are no thicker than the thickness measured when the mail item is pressed between rollers
26 and 27.
[0048] Electronic control unit 9 also calculates a decompressed pack length Ld (to allow
for expansion of the mail items as described above) by multiplying length Lc by an
expansion factor Fc (determined experimentally) which takes into account expansion
of the accumulated mail items after they are measured (which involves compressing
the mail items) :
[0049] A first threshold value P1 defining the maximum length of a compressed pack of mail
items, and a second threshold value P2 defining the maximum length of a decompressed
pack of mail items are also defined; the latter maximum length being defined so the
decompressed pack can be accommodated in a container K (Figure 1).
[0050] The sorting device continuously determines the following conditions for each accumulating
device 12, enables or disables loading of the mail items into accumulating device
12, and accordingly indicates the fill level of the accumulating device as follows
:
a) if the decompressed pack length Ld is below first threshold P1, sorting continues
normally, and no warning signal is emitted;
b) if the decompressed pack length Ld is above first threshold P1 but below second
threshold P2 (i.e. a decompressed pack of mail items can be accommodated in container
K), sorting continues, but an almost-full warning signal is emitted, for example,
by flashing button 42, to indicate the accumulating device is nearly full and only
a small margin remains in which to accommodate the mail items in the relative container
K;
c) if the decompressed pack length Ld is just above second threshold P2 (i.e. a decompressed
pack of mail items can just about be accommodated in container K), sorting is stopped
and a full warning signal is emitted.
[0051] When an almost-full warning signal is emitted, the operator OP may decide to cut
off flow of the mail items from conveying device 22 to the almost-full accumulating
device 12 manually, and remove the contents of the accumulating device, which can
undoubtedly be accommodated in container K with no manual compression required.
[0052] When the accumulating device is emptied and relative button 42 is pressed, electronic
control unit 9 associates the identification code list and characteristics of the
mail items fed into the accumulating device with the container identification code
printed on the tag affixed to the container by the operator, so as to record a precise
trace between the mail items and container K. This is known as computer closure of
the pack, and may be performed by prolonged pressure on button 42, which accordingly
flashes rapidly to indicate no more mail items can be loaded into the accumulating
device until the button is pressed again.
[0053] When prolonged pressure is applied on button 42, a signal is sent to electronic control
unit 9 indicating closure of pack 4b of mail items, and, if the relative tag has not
yet been printed, a tag 41 is printed showing the destination of the mail items in
pack 4b, identification of pack 4b of mail items 7 in the form of a bar code, as well
as processing and system information and the date and time the tag was printed.
[0054] Pressing the button again allows mail items to be fed once more into the accumulating
device, and the button light goes off.
[0055] When length Ld exceeds second threshold P2, electronic control unit 9 cuts off flow
of mail items 7 from conveying device 22 to the relative accumulating device 12.
[0056] This condition is indicated by a steady light of button 42.
[0057] In which case, the operator (or robot, if any) transfers the whole pack to container
K, compressing the pack by hand to a greater or lesser degree, depending on the set
values of thresholds P1 and P2.
[0058] The operator OP then exerts prolonged pressure on button 42, in response to which
the device records and associates the identification code list and characteristics
of the mail items with the identification code of the container on the tag, if already
printed (to effect computer closure of the pack), and button 42 flashes rapidly to
indicate no more mail can be loaded into the accumulating device.
[0059] If the tag relative to the pack of mail items has not yet been printed, in response
to the above command, a tag 41 is printed showing the destination of the mail items
in pack 4b, identification of pack 4b of mail items 7 in the form of a bar code, as
well as processing and system information and the date and time the tag was printed.
[0060] Pressing the button again allows mail items to be fed once more into the accumulating
device, and the button light goes off.
[0061] The length and width data of each measured mail item 7 may be used by electronic
control unit 9 to calculate the volume of the mail item as follows :
[0062] The calculated volumes may be added sequentially to calculate the volume Vp of the
pack forming in each accumulating device 12; which volume information is associated
with the logic output indicator.
[0063] The advantage of the invention lies in enabling a different operating procedure providing
the operator with an indirect but precise indication of the actual fill level of each
accumulating device.
[0064] Each container is thus filled precisely with the mail items fed into the respective
accumulating device, so the computer tracking system is able to keep a record of the
identification code list and characteristics of the mail items fed into the accumulating
device, and accurately associate the list with the container identification code (e.g.
bar code) printed by the sorting device on the container tag.
[0065] Since the containers for mail items removed from different accumulating devices 12
may differ in shape and size, thresholds P1 and P2 may differ from one accumulating
device 12 to another.
[0066] Thresholds P1 and P2 may also vary according to the type of mail items being sorted,
in that the best arrangement of the mail items inside the containers (fill level and
density) is achieved by calculating the compression factor Fc of the mail items and
setting the threshold accordingly.
1. A mail sorting device (1) comprising :
- a mail receiving and singling module (3) which receives packs (4) of mail items
(7) and feeds out single, i.e. physically separate, mail items; and
- a sorting module (11) input-connected to an output of the receiving and singling
module (3), and which directs each incoming single mail item (7) to a selected accumulating
device (12) forming part of a number of accumulating devices (12) of the sorting module
(11);
the sorting device being
characterized by comprising a measuring device (15) located upstream from the sorting module (11) to determine
at least one dimensional parameter (dc, de) of the single mail item fed to said sorting
module (11);
the dimensional parameter information (dc, de) being associated with an indicator
(E1, E2, ..., En, E20) of the selected accumulating device to perform a procedure
by which to determine the fill level (Lc, Ld) of the accumulating device as a function
of the number and size of the mail items fed to the accumulating device (12).
2. A device as claimed in Claim 1, wherein said measuring device (15) determines at least
the thickness (dc, de) of the mail item.
3. A device as claimed in Claim 2, wherein said measuring device (15) determines the
thickness (dc) of the mail item in a compressed condition, wherein the measuring device
(15) exerts pressure on opposite faces of the flat, rectangular mail item.
4. A device as claimed in Claim 2 or 3, and comprising a processing unit (9), which receives
at least said thickness (dc, de) and calculates at least one characteristic dimension
(Ld, Lc) of the pack (4b) of mail items forming in each accumulating device (12).
5. A device as claimed in Claim 4, wherein said characteristic dimension is calculated
by adding the successively acquired thicknesses.
6. A device as claimed in Claim 5, wherein said characteristic dimension is a length
Ld of the pack in a decompressed condition, obtained by multiplying a length Lc by
an expansion factor Fc which takes into account the tendency of the accumulated mail
items to expand after they are measured;
said length Lc being obtained by adding the successively acquired thicknesses dc of
the mail items in a compressed condition, wherein the measuring device (15) applies
pressure on opposite faces of the flat, rectangular mail item.
7. A device as claimed in Claim 6, wherein said processing unit defines a first threshold
value P1 defining, for a given accumulating device (12), a maximum length of a compressed
pack of mail items; and a second threshold value P2 defining a maximum length of a
decompressed pack of mail items; said second threshold value P2 being defined to accommodate
the decompressed pack inside a container (K) with substantially no compression of
said pack required.
8. A device as claimed in Claim 7, wherein, if the length Ld of the decompressed pack
is below the first threshold P1, sorting is continued.
9. A device as claimed in Claim 7 or 8, wherein, if the length Ld of the decompressed
pack is above the first threshold P1 and below the second threshold P2, sorting is
continued, and an almost-full accumulating device signal is emitted to indicate little
space remaining in the accumulating device (12) for further mail items.
10. A device as claimed in Claim 7, 8 or 9, wherein, if the length Ld of the decompressed
pack is above the second threshold P2, sorting is stopped, and a full accumulating
device (12) signal is emitted.