[0001] This invention relates to the printing of a franking impression and other matter
on mail items such as envelopes and labels.
[0002] Franking machines are used for franking mail items by the printing of a franking
impression on the mail item to indicate that a postal value has been charged for the
transmission of that item. In the case of small mail items in which an envelope contains
the material being sent, the franking impression is usually applied directly to the
envelope. However with larger items such as parcels and packets too large to pass
through the franking machine, the franking impression is usually applied to a label
which is subsequently adhered to the item.
[0003] Franking machines include a printer to print the franking impression and other material
such as an advertising slogan on the envelope or label by means of type characters
which engage an inked roller and then the surface of the mail item or alternatively
press an inked ribbon against the surface of the mail item. The franking includes
the value of postage and the date of franking and may include further data such as
an identifier for the franking machine and coded data for checking the validity of
the franking. Commonly the printer has a printing drum which is rotated to bring type
carried by it into printing engagement with an inked roller and mail item. The drum
may carry fixed type to print invariable data such as an officially authorised pattern
of franking impression together with type characters which can be selected for the
printing of the variable data such as the date and value of postage charged. The type
characters for printing variable data are usually carried on rotatable type wheels
which can be turned to bring selected characters into an operative printing position.
Such printers require complex mechanisms for setting the type wheels and also electro-
mechanical transducers for generating electrical signals indicative of the setting
of the type wheels for use by electronic circuits for carrying out accounting functions
related to the use of the franking machine.
[0004] It has also been proposed to use other forms of printer such as a thermal dot matrix
printer using a thermal transfer process for the transfer of ink from a transfer ribbon
to the surface of the mail item. In such printers a print head has a plurality of
selectively heatable print elements which bear against a rear face of the transfer
ribbon. The front face of the ribbon carries a layer of inked material which is melted
by the heated elements in the vicinity of those elements and thereby transfer the
ink to the surface of a mail item which is fed in contact with the front face of the
ribbon. Such printers have the advantage over the earlier mechanical printers in that
they are electrically operated and hence do not require the provision of complex mechanisms
for setting values to be printed.
[0005] However both forms of printer require the provision of an inked roller or inked ribbon.
As the rollers are used, ink is removed and after a number of passes of the type past
the printing position the ink remaining in the roller is reduced to a level at which
the printing would be too feint to be acceptable. In the case of thermal transfer
ribbons, the entire thickness of ink is removed by the heated printing elements and
hence the ribbon is not able to be re-used. Accordingly at intervals during the use
of a franking machine it becomes necessary to interrupt use of the machine in order
to replace the used ink roller ribbon with a correspondingly fully charged roller
or ribbon. Such interruptions are inconvenient to the user of the machine.
[0006] According to one aspect of the invention a franking system comprises the combination
of a mail item such as an envelope or label having an area on a face thereof treated
with sensitive material and a franking machine including a printing device selectively
operable to print a franking impression on said face of the mail item by changing
the visual state of selected portions of said area of sensitive material.
[0007] According to another aspect of the invention a franking machine includes a printing
device comprising selectively operable elements effective upon operation to change
the visual state of selected portions of an area of the face of a mail item treated
with sensitive material.
[0008] According to a further aspect of the invention a mail item such as an envelope or
label having an area on a face thereof treated with sensitive material.
[0009] Preferably the sensitive material is responsive to the application of heat to change
its visual state.
[0010] An embodiment of the invention will now be described in more detail by way of example
with reference to the drawings in which:-
Figure 1 illustrates diagrammatically the functional elements of a franking machine
and
Figure 2 shows a mail item.
[0011] Referring first to Figure 1, a franking machine consists of an accounting and control
unit 10 and a printing unit 11. The accounting and control unit 10 includes a microprocessor
12 for carrying out accounting and control functions and is provided with a keyboard
13 to enable a user of the machine to input data and command signals to the microprocessor.
A display device 14 is provided to display data keyed in by the user and also to display
machine status information to the user. Accounting data relating to usage of the machine
is held in memories 15. The memories are arranged to store a plurality of copies of
the accounting data in order that in the event of a fault in storage of the data an
un-corrupted copy of the data can be subsequently retrieved from the memories. In
order to ensure that the machine cannot be used in a fraudulent manner, the microprocessor
and memories are contained within a secure housing 16 to prevent unauthorised access
to the circuits. The construction and operation of such accounting and control circuits
are well known in the franking machine art and therefore it is believed to be unnecessary
for an understanding of the invention to describe these circuits in more detail.
[0012] The printing unit 11 receives print control signals over lines 17 and includes a
printing head 18 driven by a driver circuit 19. The printing head comprises a plurality
of selectably heatable elements positioned immediately adjacent a feed path for mail
items 20. The elements may be arranged in a single row extending across the feed path
in which case the elements may be constituted by segments of a strip of electrically
resistive material, the elements being defined by electrical connections spaced along
the length of the strip. The electrical connections are connected to outputs of the
driver circuit.
[0013] The feed path for the mail items 20 extends between the upper portion 21 of the printer
housing in which the print head is located and a base portion 22 of the housing. Feed
and co-operating pressure rollers (not shown) are provided in the upper and base portions
of the printer housing to feed the mail items along the feed path, at least one of
the feed rollers being powered by an electric drive motor.
[0014] Referring now to Figure 2 which shows a mail item consisting of an envelope. As is
conventional, the front face of the envelope is intended to carry destination address
information 23 within an area 24 disposed in the lower part of the face. An area 25,
disposed along the upper part of the face, is utilised to carry a franking impression
26. The upper area may also be utilised to carry advertising material 27. In order
to enable the franking impression to be applied to the envelope, the upper portion
of the front face of the envelope is treated with material sensitive to heating. This
material, prior to the application of heat, is substantially not visible or may be
a uniform colour throughout the upper area of the face of the envelope. However when
the material is subjected to heating, the material assumes a colour which contrasts
with the that of the unheated material. It may be desired to print the franking in
one colour and the advertising material in another colour. If this is desired the
area 25 at the upper part of the face is divided into sub-areas 25a and 25b, one sub-area
25a being treated with material which assumes one colour after heating and the other
sub-area 25b is treated with material which assumes the other colour after heating.
[0015] When it is desired to carry out a franking operation, the user of the machine enters,
by means of the keyboard 13, the value of postal charge. The microprocessor 12 carries
out a check to ensure that the credit value held in the memories 15 is sufficient
for this value of postal charge and in the event that this check is satisfactory print
control signals are passed to the print head driver circuit 19. The mail item 20 is
fed into the feed path in the printer unit 11 with an orientation such that the upper
area 25 which has been treated with heat sensitive material will pass immediately
under the print head 18. The elements in the print head 18 are selectively heated
by the driver circuit 19 such that the elements are heated selectively and successively,
in synchronism with feeding of the mail item 20 along the feed path past the print
head 18, in such a manner that the desired pattern of printing is obtained on the
mail item. Means are provided to sense the feeding of the mail item past the print
head firstly to ensure that a mail item is present and secondly to ensure that the
print head is driven in synchronism with feeding of the mail item.
[0016] While the envelope described hereinbefore is treated only on an upper area 25, if
desired the entire face of the envelope may be treated with sensitive material. Treating
of the entire face would permit printing of the destination information to be printed
by a printer having selectively heatable print elements. The printer for printing
the destination information may if desired be incorporated in the printing unit 11
of the franking machine.
[0017] Conveniently, the envelopes may be formed of paper which has been treated in bulk
with sensitive material. Alternatively, particularly where it is desired to selectively
treat the envelope either such that only the upper area 25 of the envelope is treated
or where it is desired to treat sub-areas 25a, 25b of the envelope with material which
assumes different colours, the front faces of the envelopes may be treated after manufacture
of the envelopes. While the mail items have been considered to consist of envelopes,
it will be appreciated that the franking and or destination information may be applied
to adhesive labels intended to be affixed to larger packets and parcels.
[0018] Sensitive materials suitable for treating the mail items are sometimes liable to
deterioration over a period of time with the result that the printing may become feint
or un-readable. Accordingly if desired the printer unit of the franking machine may
be provided with means, operative subsequent to printing on the mail item, to desensitise
or lower the sensitivity of the material with which the mail item has been treated.
1. A franking system comprising the combination of a mail item (24) such as an envelope
or label and a franking machine (10,11) characterised in that the mail item (24) has
an area (25) on a face thereof treated with sensitive material and in that the franking
machine (10,11 ) includes a printing device (11) selectively operable to print a franking
impression (26) on said face of the mail item (24) by changing the visual state of
selected portions of said area (25) of sensitive material.
2. A franking system as claimed in claim 1 further charactersied in that said sensitive
material assumes a colour after being subjected to heat contrasting to the colour
of the material prior to being subjected to heat and said printing device (11) is
operable to heat selected portions of the material.
3. A franking machine characterised by the provision of a printing device (11) comprising
selectively operable elements (18) effective upon operation to change the visual state
of selected portions of an area (25) of the face of a mail item (24) treated with
sensitive material.
4. A franking machine as claimed in claim 3 further characterised in that said elements
(18) are operable to apply heat selectively to the area (25) of the face of the mail
item (24).
5. A mail item such as an envelope or label characterised in that an area (25) on
a face thereof is treated with sensitive material.
6. A mail item as claimed in claim 5 further characterised in that the visual state
of the sensitive material is changed by the application of heat thereto.
7. A mail item as claimed in claim 5 or 6 further characterised in that one area (25a)
of the face of the item is treated with a first sensitive material and a second area
(22b) is treated with a second sensitive material.
8. A mail item as claimed in claim 7 further characterised in that said first material
assumes a first colour and said second material assumes a second colour contrasting
with said first colour in response to the application of heat thereto.
9. A franking machine as claimed in claim 3 or 4 further characterised by the provision
of means operative subsequent to operation of the printer (11) to desensitise or lower
the sensitivity of the area (25) treated with sensitive material.