Patent Application
20080029220
Referring now to the figures of the drawing in detail and first, particularly, to
Each voltage divider in the measurement circuit is in each case connected at one end to the ground pole outside the instrument transformer 330, and at the respective other end to a voltage pole of an AC voltage source 331 within the instrument transformer 330. The AC voltage source 331 can produce a preferably symmetrical AC voltage with an undefined waveform, for example a sinusoidal, triangular-waveform or square-wave AC voltage. The frequency of the AC voltage should be in the range from 50 to 120 Hz and should therefore on the one hand be sufficiently high that the measurement is not subject to any polarization effects, while on the other hand it should be sufficiently low that the capacitances of the lines cannot affect the measurement.
Within the instrument transformer 330, each voltage divider has a center tap which is electrically conductively connected to in each case one contact a, b and c of a changeover switch 333. By way of example, the contact a can be connected via switching device to the contact m of the changeover switch 333, in order to measure a measurement voltage um at the center tap of the first voltage divider. The AC voltage source 331 is connected to ground potential via the respective other voltage pole. The contacts e and s of the changeover switch 333 are used for measurement of the ground potential and, respectively, of the voltage potential on the voltage dividers. The changeover switch 333 may preferably use electronically controllable switches to form an analog multiplexer, and for control purposes, is connected to a microprocessor. At least one sample and hold (S&H) circuit 337 and one analog/digital converter 338 are connected to the output of the changeover switch 333 via an impedance converter 335. The sample and hold (S&H) circuit 337 converts a measurement AC voltage um to a peak DC voltage Ûm, which corresponds to the peak value of the DC voltage. The analog DC voltage Ûm is stored in analog form, and is then converted to a digital value Um. The digital value is temporarily stored in digital form in the instrument transformer 330 until it is checked by the microprocessor.
As shown, the instrument transformer 330 may be a component of an input/output unit 33 of an evaluation and control circuit 3, or may be formed separately and connected between the electrodes and the evaluation and control circuit 3. The instrument transformer 330 can be switched and controlled via a driver circuit 339 which is connected to the microprocessor bus.
A collecting trough 26 is disposed underneath the moisturizing storage device 234 in the direction of the force of gravity. A liquid tanker 24 is connected via a flexible supply tube 241, via a first pump chamber 253 of the pump 25 and via a flexible supply tube 251 to the moisturizing storage device 234, and the collecting trough 26 for liquid droplets running out is connected via a flexible outlet tube 261 to a second pump chamber 254 of the pump 25. The second pump chamber 254 is connected via a flexible outlet tube 262 to the liquid tank 24, with the flexible outlet tube 262 ending at the closure piece 242 of the liquid tank 24. The flexible supply tube 241 starts at the lower filling level in the liquid tank 24, passes through the closure piece 242 of the liquid tank 24, and ends at the pump 25. The flexible supply tube 251 to the moisture reservoir starts at the output of the pump 25 and ends above the moisturizing storage device 234 in a guide unit. The flexible supply tube 251 is connected for flow purposes via at least one opening in the guide unit to the moisturizing storage device 234. If the pump 25 is in the form of a multiple flexible-tube pump, the flexible tubes 241 and 251 as well as the flexible tubes 261 and 262, respectively, are in each case combined to form one flexible tube, and are passed through the pump 25.
A tank measurement cell 39 in the liquid tank 24 contains an electrically isolating spacer 390 for two electrodes 391 and 392. The electrical lines 3801, 3802 are both electrically connected to the electrodes 391 and 392, for example via glass bushings 381, 382 arranged in the closure piece 242. The electrical lines which are connected on the outside are protected by a second shielded cable 38. The first and second shielded cables 334 and 38 are intended to have a cable capacitance which is as low as possible.
The result of the liquid wetting of the electrodes of the measurement cells is as follows:
A spacer 390 composed of glass in practice has a minimum specific electrical conductivity of κGlass≈10−14 AV−1 cm−1 when not wetted by the liquid. The controller 3 does not react to the measurement by means of the tank measurement cell 39 until at least one lower filling level is exceeded. The difference of 8 to 11 orders of magnitude when wetted by the liquid can be clearly detected. The measurement can be used to distinguish between an empty liquid tank 24 and a liquid tank 24 which is not empty. This is true, of course, only when the machine is not moving.
The moisturizing storage device 234 has an electrically isolating storage material with adequate capacity to store the electrically conductive liquid and is fitted, for example, with three electrodes, which are arranged spaced apart from one another in a row, with the row in this case being parallel to the perpendicular to the center of the earth. The microprocessor can use the voltage values measured at different points to draw conclusions about the state of the moisturizing storage device 234, and can drive the motor 253 for the pump 25 when required, in order to supply liquid. This makes it possible to produce a first variant of intelligent dynamic sealing liquid supply (IDS), by which the moisture in the sponge can be controlled by software. The pump 25 can be switched off when no letter envelopes need to be sealed. A switch 2374 which is coupled to an operating button 2372 is used to switch the pump 25 on and off manually. The switch 2374 is connected to an evaluation and control circuit 3, which is in turn connected via a control line 31 to the pump 25, or to its motor 252. Depending on the characteristic of the motor 252, it is controlled by variation of a voltage level or of a pulse repetition frequency. If the pump 25 is in the form of a symmetrical multi-chamber flexible tube pump, the first pump chamber 253 is used to supply the moisture reservoir 234, and the second pump chamber 254 is used to extract excess liquid from the collecting trough 26.
The tank measurement cell 39 is attached to the closure piece 242 on the inside and is electrically connected by an insulated double line 3801, 3802 to the connecting terminals x and y of the instrument transformer 330 on the input/output unit 33 of the evaluation and control circuit 3, which allows an electric alternating current to flow via the electrodes 391, 392 through the liquid, and evaluates the voltage drop. A program memory FLASH 34, a non-volatile memory NVRAM 36 and a main memory RAM 37 are connected for digital evaluation during operation to the processor 34, and the processor 34 is coupled via the bus to the input/output unit 33. When the liquid tank 24 is full, an appropriate signal to reduce the pump power can be supplied from the evaluation and control circuit 3 to the motor 252 for the pump 25. When the liquid tank 24 is empty, an appropriate signal to increase the pump power can be supplied from the evaluation and control circuit 3 to the motor 252. The input/output unit 33 of the evaluation and control circuit 3 is connected bi-directionally to a franking machine 4. The latter likewise has an input/output unit 40, which is connected to a microprocessor controller 43. The keyboard 41 of the franking machine 4 is coupled to the latter. The pump power can be preset manually by the keyboard 41, the microprocessor 43 of the franking machine 4 and via the input/output unit 40. The display 42 can be used for a status display, indicating whether, for example, the moisturizing apparatus is or is not activated. This is particularly advantageous during operation for servicing purposes. The power of the pump 25 can be matched to the transport speed and to the paper quality of the letter envelopes 1 in order in this way to ensure that the glued edges are adequately moisturized. A first sensor 2321 is arranged in the movement path of the envelope flaps in the area of the moisturizing storage device and produces a signal to initiate the pump only when an envelope flap passes the sensor 2321. A second envelope sensor 2322 detects the front edge of the envelope and is used to start the IDS (intelligent dynamic sealing liquid supply). The IDS is advantageously started before a blade detects the envelope flap, and lifts off the envelope. This ensures adequate penetration of the sealing liquid into the moisturizing storage device 234 without over moistening, before an envelope flap passes the first sensor 2321.
The solution according to the invention contains the configuration of electrodes for conductivity measurement for example in a sponge, which is used to apply moisture to the gum on the letter envelope flap. The conductivity measurement offers a sufficiently accurate measurement for the moisture in the sponge, and is sufficiently sensitive to detect very minor changes, and to react to them. However, this is dependent on the use of a sufficiently conductive sealing liquid. Since the commercially available sealing liquids, including the water that is normally used, are not sufficiently conductive, set-up salts, such as sodium chloride, potassium chloride, sodium acetate or sodium lactate can be used, dissolved in the water, in order to adjust the conductivity.
According to published, non-prosecuted German patent application DE 10 2006 014 164.4, a penetration agent is used in addition to water for the sealing liquid. To be precise the pure penetration agent scarcely increases the electrical conductivity with the water, because of its non-ionic character, in the same way as non-ionic surfactants. However, the ethyl lactate which is used as the penetration agent is stabilized in an aqueous solution with sodium lactate (Na lactate). Approximately 1.2% sodium lactate could be used in this case. The increase in the electrical conductivity would be surprisingly clear with this mixture.
The exemplary embodiment includes the flowchart, as shown in
G
m3
=G
v·(Us−U3)/U3 and XT=|Gm3| /9/
and/or—corresponding to equation /8/ from the predetermined geometric parameters d and A of the measurement cell, a corresponding value of the specific electrical conductivity:
κm=d·(Us−U3)/U3·Rv·A and XT=|κm| /10/.
The digital basic tank value XT is then compared with the digital comparison values A, B and C. Although this is not shown in any more detail in
A second checking step 106 is used to find out whether the digital basic tank value XT is less than the second digital comparison value B, with the latter being less than the highest digital comparison value. A jump is then made to a third checking step 108. Otherwise, if the digital basic tank value XT is not less than the second digital comparison value B, the jump is then made to a step 107 and a second binary value N=10 is set in the memory, in order to identify the second state found, for example in which there is drinking water or mains water in the tank.
A third checking step 108 is used to find out whether the digital basic tank value XT is less than the third digital comparison value C, with the latter being the smallest digital comparison value. A jump is then made to a fourth step 110 in order to signal, for example in order to report via the display, that the sealing liquid should be replenished.
Otherwise, if the digital basic tank value XT is not less than the third digital comparison value C, then a jump is made to a step 109 and a third binary value N=11 is set in the memory, in order to identify that the third state has been found, for example that there is distilled water or desalinated water in the tank.
The process then jumps back from the step 110 to the start of the third step 103. However, if the sealing liquid has now been replenished, one of the steps 105, 107 and 109 is then carried out, thus classifying the sealing liquid used in the tank.
A jump is made from the steps 105, 107 and 109 to a fourth checking step 111, and the binary value N set in the memory is compared with the stored permissibility value Z, and a start step 112 for the intelligent dynamic sealing liquid supply (IDS) is reached when the binary value N is less than or equal to the stored permissibility value Z. Otherwise, that is to say if the binary value N for identification of the tank state is not less than or equal but is greater than the stored permissibility value Z, then the routine is ended (step 113).
The IDS routine therefore cannot be started if the sealing liquid used in the tank does not comply with the requirements of the permissibility value Z. Once the IDS routine has been started in the step 114, a routine is carried out, containing a number of subroutines. The switch 335 is switched in step 114 such that its contacts a and m or b and m are electrically conductively connected. The measurement cells of the moisturizing storage device are then checked, and in the process analog AC voltage elements u1 and u2 are sampled at the center tap of the first and second voltage dividers. Each voltage divider contains the series resistance Rv1 and Rv2 as well as a respective measurement resistance Rm1=1/G1 and Rm1=1/G1, which respectively correspond to the reciprocal 1/G1 and 1/G2 of a conductance G1 and G2 which can be determined by calculation. The measured analog AC voltage elements u1 and u2 are rectified and are temporarily stored in analog form in the S&H circuit as analog peak DC voltage values Û1 and Û2. The analog value is then in each case converted to a respective digital value U1 and U2, and these are temporarily stored in digital form in a memory. After this has been checked by the microprocessor, either a first and a second conductance and/or a corresponding first and second value of the specific electrical conductivity are/is determined by calculation. A comparison is then carried out with the digital basic tank value. Corresponding substeps have, however, not been illustrated in any more detail in
A fifth checking step 115 is reached after a step 114. If the second conductance or second value of the specific electrical conductivity X2 is less than the digital basic tank value XT, then a jump is made to step 116, in which the pump is switched on, and its drive is set to a high, first power.
Otherwise, a check is carried out in a sixth checking step 117 to determine whether a first conductance or a first value of the specific electrical conductivity X1 is less than the digital basic tank value XT. In a situation such as this, a jump is made to step 118, in which the pump is switched on, and its drive is set to a low, second power. After steps 116 and 118, a jump is made back to the start of the routine in step 114, in which the values measured by the measurement cells are checked and processed.
Otherwise, if the first conductance or first value of the specific electrical conductivity X1 is not less than the digital basic tank value XT, then a check is carried out in a seventh checking step 119 to determine whether X1 is in a tolerance band 0.98 X2<X1<1.02 X2. If this is the case, then the pump is switched off in a step 120. However, if this is not the case, then the process moves to an eighth checking step 121.
The eighth checking step 121 is used to check whether a first conductance or a first value of the specific electrical conductivity X1 is less than the second conductance or second value of the electrical conductivity X2. If this is the case, then a jump is made to step 122, in which the pump is switched on and its drive is set to a low, second power. After steps 120 and 122, a jump is made to a step 126, in which the moisturizing and sealing process for a letter envelope is enabled when the letter envelope flap passes the first sensor 2321. The pump is then operated for a defined time, which contributes to compensation for the loss of liquid in the moisturizing means during the moisturizing process. After step 126, a jump is made back to the start of the routine in step 114, in which the values measured by the measurement cells are checked and processed.
However, if it is found in the eighth checking step 121 that a first conductance or first value of the electrical conductivity X1 is not less than the second conductance or second value of the electrical conductivity X2, then the pump is switched off in step 123 and the jump is made to step 124, in order to repeat the tank sensor check. In this case, the same routine as in the third step 103 is carried out again, as has already been explained above. A jump is then made to a checking step 125 in order to repeat the check—as known from the third checking step 108.
If it is found in the checking step 125 that the digital basic tank value XT is less than the third digital comparison value C, with the latter being the lowest digital comparison value, then a jump is made to a final step 127 in order to emit a false message or to signal the end of the moisturizing process. Otherwise, a jump is made to step 126, in which the moisturizing and sealing process for a letter envelope is enabled.
The dynamic control of the liquid supply to the moisturizing storage device for a moisturizing apparatus for application of sealing liquid to envelope flaps of letter envelopes, according to a second embodiment, will be explained with reference to
The two other electrodes 2343 and 2341 of the moisturizing storage device are connected to the measurement points u and w of the instrument transformer 330, and are at their respective measurement potential. The electrode 2342 is connected to the measurement point v of the instrument transformer 330 and is at ground potential. The two electrodes 2342 and 2343, as well as 2342 and 2341, respectively form a measurement cell for the electrical conductivity and are separated from one another by a respective height K1 or K2. The specific electrical conductivity κ1, κ2 is dependent on the nature of the sealing liquid.
In the routine of the next, third step 206, a tank measurement cell 39 is checked, and in the process an analog AC voltage element u is sampled at the center tap of the third voltage divider. The measured analog AC voltage value u is rectified and is temporarily stored, in analog form, in the S&H circuit as the analog peak DC voltage value Û3. The analog value is then converted to a digital value U3, and is temporarily stored in digital form in a memory. After this has been checked by the microprocessor, a digital basic tank value XT is determined by calculation. The digital comparison values A and B are once again used for classification of the sealing liquid on the basis of its conductance or electrical conductivity. If it is then subsequently found in a second checking step 207 that the digital basic tank value XT is less than the first digital comparison value A, then a jump is made to a third checking step 209. Otherwise, if the digital basic tank value XT is not less than the digital comparison value A, then a jump is made to a step 208, and a first binary value N=01 is set in the memory in order to identify the first state found, that there is an electrically conductive sealing liquid in the tank.
In the third checking step 209, it is found that the digital basic tank value XT is less than the second digital comparison value B, with the latter being less than the higher digital comparison value A. This undershooting results in a jump to the display step 213 in order, for example, to signal to the user: “Please replenish set-up salt!”. A jump is made back from the display step 213 to the start of the routine in step 206.
Otherwise, if the digital basic tank XT is not less than the second digital comparison value B, then a jump is made to step 210 and the second binary value N=10 is set in the memory, in order to identify the second state found, for example that there is drinking water or mains water in the tank.
A jump is made from the checking steps 207 and 209 to a fourth checking step 211. A check is carried out in the fourth checking step 211 to determine whether the state value N has exceeded the permissibility value Z*. If this is the case, then a check is carried out in a fifth checking step 213 to determine whether the use of an alternative sealing liquid is permissible. If this is the case, then a standard program 500 is run, without any conductivity measurements. Otherwise, if this is not the case, the end (step 228) is reached. If it is found in the fourth checking step 211 that the state value N has not exceeded the permissibility value Z*, then a start step 212 is reached for a routine for intelligent dynamic sealing liquid supply (IDS). The IDS routine includes the steps 212 to 227 and corresponds to the steps 112 to 127 of the IDS routine according to the first variant, which has already been explained with reference to
The measurement circuit 332 contains three voltage dividers, whose respective series resistances Rv1, Rv2 and Rv3 are connected on one side to one pole of the AC voltage source 331 and on the other side to the measurement points u, v and w of the measurement circuit 330. The voltage divider taps correspond to the abovementioned measurement points.
The measurement cells, whose electrical equivalent circuits have been illustrated, are located between each tap and ground potential. The respective reciprocal of the conductance corresponds to a resistance Rm1, Rm2 and Rm3 of the liquid in each measurement cell. A capacitance Cp1, Cp2 and Cp3 is in each case connected in series with them in order to simulate the polarity processes in the liquid. A respective line capacitance CL1, CL2 and CL3 of the lines in the cables 334 and 38 (
The first and third operational amplifiers OP3 are a component of an impedance converter assembly 335 with an inverting output g and a non-inverting output I, which are each followed by precision rectifiers. The precision rectifiers are part of a rectifier assembly 336 and each contain an operational amplifier OP2 and OP4 with a respective diode D1, D2 in the negative feedback path, which produces a connection from the output to the inverting input of the respective operational amplifier. For example, if the output of the operational amplifier OP2 and OP4, respectively, is connected to the n-region of the respective diode D1, D2, then the p-region of the respective diode D1, D2 forms a respective output h or k. The respective other non-inverting input of the respective operational amplifier OP2 or OP4 is electrically conductively connected to the output I of the first operational amplifier OP1 or, respectively, to the output g of the third operational amplifier OP3.
The instrument transformer part shown in
RDS=Roff≈1010Ω when UGS=0 V
and
RDS=Ron≈30Ω when −UGS=20 V.
For example, if an AC voltage is applied to the voltage divider and has a peak voltage ûc at the tap c. This is applied by the input-side operational amplifier OPc to the drain connection of the MOSFET. A positive voltage UB=+9 V is applied to a separate bulk connection B, in order to prevent the pn-junction between the source S and the bulk B being switched on when the input voltages ûc are positive. A control voltage UGS is applied via the respective gate, for example Gc, via a drive circuit, which is not shown but is itself driven by the microprocessor in order to operate the respective MOSFET switch.
The visible side of the holding plate 235, which faces away from the moisturizing storage device, has curved areas which merge smoothly into the corresponding curved areas on the blade 231 when the holding plate 235 is plugged on. The lines 3341, 3342 and 3343 are carried within a cable 334, outside the blade. The exploded illustration allows the abovementioned mounting panel 2310 to be seen within the compartment 2311. The lines 3341, 3342 and 3343 are guided on the mounting panel 2310 within the compartment 2311 and are electrically conductively connected to the three electrodes 2341, 2342 and 2343. The three electrodes are in the form of outer hollow cylinders which, in the present example, are arranged horizontally in a row and are separated from one another by equal distances. An inner hollow cylinder 23111, 23112 and 23113 is in each case arranged in the outer hollow cylinder, and is mechanically connected to the mounting board 2310. The moisturizing storage device 234 is, for example, a sponge, and the sealing liquid is normal mains water. The blade 231 is used to raise the flaps, to hold the sponge and for mechanical attachment of the electrodes which are provided for measurement of the electrical conductivity. A flexible tube connecting piece 236, onto which the flexible supply tube 251 for the sealing liquid is plugged, is arranged close to the rotation axis 233 of the blade.
Alternatively, the electrodes 2341, 2343 may be in the form of annular electrodes, with the holding plate 235 being in the form of an opposing electrode. The holding plate 235 is at a defined distance from the annular electrodes and is attached to the compartment 2311, for example by at least one screw. The holding plate may be made from a metal plate, with which electrical contact is made via the electrode and a metallic inner hollow cylinder 23112.
The guide unit will be explained, in the working position, on the basis of a schematic front view of the guide unit for envelope flaps (
The conductivity measurement in step 103 or 206 includes formation of the basic tank value XT and can in this case take into account a correction factor for compensation of measured value discrepancies resulting from temperature fluctuations and production tolerances. The classification of the sealing liquid in steps 104 to 109 or 208 to 209 can also be carried out in a manner other than that shown in
Where the abovementioned example refers to an indirect measurement of the amount of liquid stored in the moisturizing storage device, in particular by conductivity measurement, then this is not intended to preclude other forms of indirect measurements of physical or chemical parameters which can be used instead of or in addition to conductivity measurement. For example, the sealing liquid that is being used can likewise be identified, or the accuracy of the identification of the sealing liquid that has been used can be increased, by measuring the weight of the amount of liquid stored in the moisturizing storage device.
| Number | Date | Country | Kind |
|---|---|---|---|
| DE102006038222.6 | Aug 2006 | DE | national |
