EP0573701A1

EP0573701A1 - Electronic franking machine

Info

Publication number: EP0573701A1
Application number: EP92201672A
Authority: EP
Inventors: Benoît Guillaume
Original assignee: Bell Telephone Manufacturing Co NV
Current assignee: Nokia Bell NV
Priority date: 1992-06-10
Filing date: 1992-06-10
Publication date: 1993-12-15

Abstract

A machine for franking mail documents (DO) and including a drive unit adapted to displace these documents successively along a detector device (DM) and a printer head mechanism (PH). The detector device detects the document and triggers the printer head mechanism to print a stamp on a predetermined printing area of the document. This electronic franking machine includes a variable delay unit (DC) which subsequently to the detection of a document delays the triggering of the printer head mechanism (PH) and thereby modifies the printing area on which a stamp will be printed. By disabling or enabling the variable delay unit (DC) such a stamp is printed either in the upper right corner area of the document or in an area at a different distance, e.g. of about 12 cm, from the right hand edge of the document respectively. The first case is suitable for printing stamps on envelopes, whereas the second case is used when stamps have to be printed on paper strips to be wrapped around mailed newspapers.

Description

The present invention relates to an electronic franking machine for franking mail documents such as envelopes, labels or any other items of mail, said machine including a drive unit adapted to displace each of said documents successively along a detector device and a printer head mechanism, said detector device being adapted to detect the presence of a document and to then trigger said printer head mechanism to print a stamp on a predetermined printing area of said document.
Such an electronic franking machine is already known in the art and an example is the "NEOPOST 7700" franking machine manufactured by NEOPOST (UK). In this known machine, the printer head mechanism after having been triggered and after some delay produced by its inertia prints a stamp on the upper right corner area of the document. Afterwards, the drive unit ejects the document from the franking machine.
Although this known franking machine is suitable for printing stamps on envelopes or on self-adhesive labels which have to be franked prior to being fixed on a package, it is not adapted to print such stamps on paper strips intended to be wrapped around mailed newspapers or magazines. Indeed, when such a paper strip is wrapped around the newspaper and its ends are glued together on the back side of the newspaper, the stamp should appear at the front side thereof. This maens that when the paper strip is in the unfolded condition, the stamp should not be printed in the upper right area of the strip but on an area located at some distance, typically 12 cm, from the right hand edge of the document.
As a consequence, the known franking machine needs to be adapted to allow a stamp to be printed on such paper strips, i.e. to print a stamp on a printing area which is different of the above mentioned predetermined printing area of the document.
A possible solution to reach this goal would be to increase the distance separating the detector device and the printer head mechanism, e.g. by the above typical 12 cm. However, such a solution is to be rejected because it unnecessarily increases the lenght of the franking machine. Furthermore, as the franking machine must still be able to print stamps on envelopes in the usual way, the detector device and the printer head mechanism have to be displaceable with respect to each other, such a displacement being required each time the type of document to be printed on is modified, e.g. from an envelope to a paper strip and vice versa.
An object of the present invention is to provide an electronic franking machine of the above known type but which is adapted to print stamps on a selected one of at least two different predetermined printing areas of the documents, i.e. on a first printing area in case of envelopes and the like or on a second printing area in case of paper strips, without displacement neither of the printer head mechanism nor of the detector device.
According to the invention, this object is achieved due to the fact that said electronic franking machine includes a variable delay unit controlled by said detector device and adapted to delay the triggering of said printer head mechanism, thereby modifying the position of said predetermined printing area.
In this way, while maintaining fixed the physical distance between the detector device and the printer head mechanism, a stamp may be printed on a selected printing area of a document by a suitable choice of the triggering delay produced by the delay unit.
In more detail, said variable delay unit includes an integrator circuit which provides the required triggering delay and controls the operation of a switch used for triggering said printer head mechanism.
Also another characteristic feature of the present invention is that said switch is a bipolar transistor switch whose base electrode is controlled via an output of said integrator circuit.
Furthermore, said integrator circuit is a resistor/capacitor integrator circuit including a variable resistor by means of which said triggering delay may be adjusted.
Still another characteristic feature of the present invention is that said resistor/capacitor integrator circuit includes a capacitor which is connected in series with a second switch to a reference voltage, said second switch enabling/ disabling the operation of said variable delay unit.
In this way, only this second switch has to be activated/ deactivated to bring the franking machine in a condition wherein it is able to print stamps on either envelopes or paper strips.
The above mentioned and other objects and features of the invention will become more apparent and the invention itself will be best understood by referring to the following description of an embodiment taken in conjunction with the accompanying drawings wherein:

Fig. 1 shows an electronic franking machine according to the invention; and
Fig. 2 shows electronic circuitry controlling the operation of the franking machine of Fig. 1.

The electronic franking machine shown in Fig. 1 is used to print postage stamps on items of mail such as envelopes, labels and paper strips to be wrapped around mailed newspapers or magazines.
The machine has an horizontal document guide channel in which items of mail or documents DO are conveyed in the direction of arrow PT between rollers such as RL which are continuously driven by a drive unit (not shown). In the guide channel, a conveyed document DO first reaches a detector device DM which detects the presence of this document DO and then passes along a printer head mechanism PH which, under the control of DM, prints a stamp on DO. By the rollers RL the document DO is then ejected from the franking machine.
In more detail, the detector device DM includes a micro-switch S1 shown in Fig. 2 and which is closed when the front or right hand edge of the document DO makes contact therewith. The closure of the switch S1 triggers a variable delay circuit DC which, after a predetermined time delay t, operates the printer head mechanism PH via a control terminal PC thereof. The time or triggering delay t is so calculated that in combination with the inertia delay of the printer head mechanism PH, the latter prints a stamp on a predetermined printing area of the document DO exactly when this area passes in front of PH.
The electronic circuitry of the franking machine, and more particularly of the variable delay circuit DC thereof, is shown at Fig. 2. DC is connected between the detector device DM which controls it and the printer head mechanism PH, electric power being supplied to PH via voltage supply terminal +VCC and ground terminal V0.
The variable delay circuit DC has an input terminal IN, an output terminal PC and a reference or ground terminal V0. The voltage supply terminal +VCC is connected to the input terminal IN via the switch S1 of the detector device DM and the output terminal PC is connected to the like named control terminal of the printer head mechanism PH.
Between IN and V0, the variable delay circuit DC is constituted by an integrator circuit comprising a series branch constituted by a resistor R1 and a potentiometer P used as a variable resistor in series with a parallel branch comprising a capacitor C in parallel with a second resistor R2 coupled to the ground terminal V0 via a switch S2. The junction point B of P and C, i.e. the output of the integrator circuit, is connected to the base electrode of an NPN bipolar transistor T of which the main emitter -to -collector path interconnects the ground terminal V0 and the output terminal PC.
The printer head mechanism PH is triggered when its control terminal PC is brought substantially at the voltage of the ground terminal V0, i.e. at 0 Volt. This occurs as follows.
When a document DO is detected by the detector device DM, switch S1 is closed so that the positive supply voltage +VCC present at the like named voltage supply terminal is applied to the input terminal IN of the variable delay circuit DC.
If the variable delay circuit DC is operative, i.e. if the switch S2 is closed, the voltage at the junction point B then increases progressively from 0 Volt, i.e. from the ground voltage at V0, towards a positive voltage V due to capacitor C of the integrator circuit being charged. The positive voltage V is equal to

wherein R1, R2 and P are the ohmic values of the like named resistors and potentiometer respectively, +VCC is the positive supply voltage at the like named supply terminal and '*' is the multiplication sign.
When the voltage at the output B reaches the base -to -emitter threshold voltage Vbe of the transistor T, i.e. after a predetermined time delay t which is function of the values of the components R1, P, C and R2, this transistor switch T is closed so that the voltage V0 is applied to the output terminal PC. As a result, the printer head mechanism PH is then triggered and the printing operation starts.
It is to be noted that the potentiometer P allows to adjust the predetermined time delay t and thereby also the position of the printed area on which a stamp has to be printed.
The purpose of resistor R2 is to allow the capacitor C to be discharged when switch S1 is opened. Hereby the the main path of the transistor switch T is opened since the voltage at B becomes lower than the base -to -emitter threshold voltage Vbe of T. The ground voltage of V0 is thereby disconnected from the control terminal PC and the printer head mechanism PH is no more triggered.
If the variable delay circuit DC is inoperative due to the switch S2 being open, capacitor C cannot be charged. As a result, when the switch S1 is then closed the positive supply voltage +VCC applied to the input terminal IN via S1 is applied via resistors R1 and P to the base electrode of the transistor switch T which immediately becomes conductive. In this case the printer head mechanism PH is thus immediately triggered upon closure of the switch S1.
Summarizing, the switch S2 enables or disables the operation of the variable delay circuit DC and therefore the generation of a zero delay and a delay t, t being adjustable by means of the potentiometer P. In other words, when the switch S2 is open, the time or triggering delay is equal to zero and the closure of the switch S1 immediately triggers the printer head mechanism PH. As a result and by taking into account the distance between the detector device DM and the printer head mechanism PH, only the inertia delay of PH determines the area whereon a stamp will be printed. In practice, the stamp is then printed in the upper right corner area of the document DO. This (open) position of the switch S2 is for instance used for printing stamps on envelopes or on self-adhesive labels which have to be franked prior to being fixed on a package. On the other hand, when the switch S2 is closed, the printer head mechanism PH is triggered a time delay t after the closure of the switch S1. This time delay t is dependent of the values of the components R1, P, C and R2. As a result, the stamp is then not printed in the upper right corner area of the document DO but at some distance, typically 12 cm, from the right hand edge of this document DO. This (closed) position of the switch S2 is for instance used for printing on the above mentioned paper strips.
It is to be noted that the micro-switch S1 of the detector device DM may be replaced by any other document detector such as for instance a lightsensitive detector. The only requirement is that the used document detector allows to interconnect the positive voltage terminal +VCC and the input terminal IN of the variable delay circuit DC.
While the principles of the invention have been described above in connection with specific apparatus, it is to be clearly understood that this description is made only by way of example and not as a limitation on the scope of the invention.

Claims

Electronic franking machine for franking mail documents (DO), said machine including a drive unit adapted to displace each of said documents successively along a detector device (DM) and a printer head mechanism (PH), said detector device being adapted to detect the presence of a document and to then trigger said printer head mechanism to print a stamp on a predetermined printing area of said document,
characterized in that said electronic franking machine includes a variable delay unit (DC) controlled by said detector device (DM) and adapted to delay (t) the triggering of said printer head mechanism (PH), thereby modifying the position of said predetermined printing area.
Electronic franking machine according to claim 1, characterized in that said variable delay unit (DC) includes an integrator circuit (R1,P; C/R2) which provides the required triggering delay (t) and controls the operation of a switch (T) used for triggering said printer head mechanism (PH).
Electronic franking machine according to claim 2, characterized in that said switch (T) is a bipolar transistor switch (NPN) whose base electrode is controlled via an output (B) of said integrator circuit (R1,P; C/R2).
Electronic franking machine according to claim 2, characterized in that said integrator circuit is a resistor/capacitor integrator circuit (R1,P; C/R2) including a variable resistor (P) by means of which said triggering delay (t) may be adjusted.
Electronic franking machine according to the claims 3 and 4, characterized in that said variable resistor (P) is coupled in series between an input (IN) of said variable delay unit (DC) and the base electrode of said transistor switch (T), said detector device (DM) controlling said variable delay unit (DC) via said input.
Electronic franking machine according to claim 4, characterized in that said resistor/capacitor integrator circuit (R1,P; C/R2) includes a capacitor (C) which is connected in series with a second switch (S2) to a reference voltage (V0), said second switch enabling/disabling the operation of said variable delay unit (DC).