Abstract:
An apparatus includes a number of apparatus components that are operable to produce an apparatus action. The components include a circuit board that is available for installation in a number of different board variants. Each circuit board variant includes a photoelectric barrier that receives an input signal from a controller of the apparatus, and that generates a photoelectric barrier output signal supplied to the controller. At least one of the circuit board variants includes a delay element that introduces a delay into the output signal from the controller that is supplied to the photoelectric barrier. The delay is matched to the particular variant of the circuit board, so that the controller, by detecting a characteristic of the delay, can identify the circuit board variant of the currently-installed circuit board. The controller then controls the components to produce the apparatus action dependent on the variant of the currently installed circuit board.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention concerns an apparatus having controlled components that are operated in order to produce an apparatus action, wherein the control of the components is dependent on which circuit board, among a number of different circuit board variants, is currently present in the apparatus. 
     The invention more specifically concerns a printing apparatus of the type using an inkjet printing device and a controller that controls printing, as an apparatus action. Such a printing apparatus is suitable for use in franking machines, addressing machines and other mail processing devices. 
     2. Description of the Prior Art 
     An inkjet printing device is equipped in a known manner with an inkjet printing module and a transport device that has a transport belt in order to transport flat items to be printed in a transport direction past the printing module. A pressing device presses the flat item onto the transport belt. The inkjet printing module has a printing carriage, an electronic control unit, and at least one ink cartridge or at least one inkjet print head that is positioned stationary in a printing position over the transport path during the printing. The printing carriage can be moved transversely to the transport direction before or after the printing for maintenance or to exchange the at least one ink cartridge or the at least one inkjet print head. The printing apparatus has a sensor circuit board with sensors in order to detect the achieved position during the transverse movement of the printing carriage. 
     From published European Patent EP 1 300 807 B1, a method and an arrangement for opening a security housing are known that, in one embodiment, has a flap that can be opened at any time in order to allow a limited access to an opening for exchanging the ink cartridge. A cover of the electronic control unit of the printing module and of the control circuits of the electronic control unit serves to protect against tampering of the franking machine via the opening. The opening can be sealed by the flap. The flap is equipped with a stop that activates a switch upon opening the flap, this switch being arranged inside the security housing. The switch interrupts the power supply of a motor of the transverse movement mechanism of the printing module in order to avoid accidents due to the transverse movement of the printing module occurring while the flap is open. Even when the transversely movable printing module has been moved into the printing position or into a position outside of the printing position, the flap remains unlocked and can be opened. However, the printing module must be moved into an exchange position situated between the printing position and one of the other positions in order to exchange an ink cartridge that is then positioned in the region of an opening. Due to the situation of the exchange position being between the printing position and one of the other positions, an additional protection of the electronic control unit of the printing module and of the control circuits of the electronic control unit is necessary, which is costly in terms of materials. 
     A printing apparatus of modular design, with a removable, box-shaped module, is known from published German Patent Application DE 20 2010 015 354 A1. The apparatus is likewise equipped with at least one inkjet print head to print on flat items during the passage of the flat items through the apparatus. The inkjet print head is moved by a printing carriage into a printing position for printing. A sensor is arranged at a frame wall of the apparatus housing. This sensor signals to a microprocessor controller that a sealing position has been reached given movement of the printing carriage out of the printing position. The sensor can be realized as a photoelectric barrier. The printing carriage of the printing apparatus thereby likewise executes an orthogonal movement relative to the transport direction of the flat items. 
     A device to exchange ink cartridges of a printing device is known from published European Patent Application EP 2073173 A1. The printing device described therein has a transport direction for flat items, a pressure device, and a printing module, with the printing module arranged stationary in the printing device relative to a pressure device, which presses the flat item onto a transport belt, which, in the transport region, acts with a predetermined stiction on a surface portion of the flat item. Printing does not take place on this surface portion but it is situated close to the region that is to be printed. An exchange position for ink cartridges is located over or in front of the transport region of the transport direction. The alignment of the ink cartridge in the printing module is such that its underside faces forward (thus toward the front side of the printing apparatus). A cartridge flap that seals the opening for the exchange cannot be opened when the ink cartridge is not located in the exchange position. By making the location of the exchange position near the front side of the printing apparatus (thus in front of all other positions), no additional protection of the electronic control unit of the printing module and the control circuits of the electronic control unit is required. 
     It is generally desirable that the production of a functional printing apparatus should be enabled using housing parts that have a greater tolerance range. In the above-described printing device, for example, the cartridge flap detection switch may not be triggered with certainty due to tolerance build-up of the assembled parts. A first design of an apparatus variant A therefore had to take place with parts that have only a slight tolerance, which made the production of the printing apparatus more expensive. A design of an apparatus variant B enables the use of parts with larger tolerance. A number of software variants, respectively appropriate for the different variants A and B are already loaded into the memory of the controller during the production of this printing apparatus. Selection (from the memory) and use of the software matched to the actual apparatus variant must take place, but it would be desirable to do so without needing to make a change to the hardware of the controller. 
     SUMMARY OF THE INVENTION 
     An object of the invention is to provide a printing apparatus that has a sensor circuit board with at least one transmitted light barrier that signals to a mainboard processor of the controller whether the printing carriage is located in a position in the region of said transmitted light barrier or not. 
     To differentiate apparatus variants, the printing apparatus according to the invention has a sensor circuit board with at least one photoelectric barrier and with a low-pass filter to delay an input signal to the photoelectric barrier that is delivered from an output of the controller, with the delay matched to the respective apparatus variant. The controller has an FPGA that forms a workflow controller in order to determine whether there is a delay in the timing of the receptacle and the controller of the output signal from the photoelectric barrier of the sensor circuit board, after a predetermined duration following the delivery of the input signal to the photoelectric barrier from the controller. 
     The physical location of the light barrier on the sensor circuit board contributes to the determination of the position of the printing carriage. A vane that interrupts the light beam of the photoelectric barrier when a corresponding position is achieved in the travel of the printing carriage is molded on the printing carriage. 
     At least one transmitted light barrier for the detection of one of the various printing carriage positions is located at the sensor circuit board. For use in apparatus variants other than a first apparatus variant, the position of the photoelectric barrier is geometrically modified in comparison to the position of the photoelectric barrier on the sensor circuit board used in the first apparatus variant. For example, if the transport direction of the flat items to be printed is in the x-direction of a Cartesian coordinate system, the position of the photoelectric barrier can be shifted in the y-direction. The sensor circuit board is advantageously mounted at a frame wall of the printing apparatus so as to be easily exchangeable. One photoelectric barrier on the sensor circuit board is located near the rear housing wall (back), and another (upon whose triggering the printing position is reached) is located further forward. This additional photoelectric barrier is shifted by a few mm on the sensor circuit board for the apparatus variant B relative to the sensor circuit board for the apparatus variant A, in order to ensure more certainty for the triggering of the cartridge flap detection switch, even given large tolerance build-up. In accordance with the invention, the circuit arrangement of the sensor circuit board, namely the arrangement of a low-pass filter on the sensor circuit board used for the apparatus variant B, makes it possible to detect the respective sensor circuit board that is in use, and since the signal delay introduced by the low-pass filter is matched to an apparatus variant, such as the apparatus variants A or B noted above, an FPGA, or software in the mainboard processor of the controller automatically “knows” which variant exists, so that the precise position of the printing carriage can be determined with the sensor for the printing position in any (in this case both) of the apparatus variants. It is additionally possible to establish even more apparatus variants without incurring a hardware cost due to an additional sensor. 
     Different variants were developed for the sensor circuit board, with a specific software version being associated with each of the variants. Known defects in the functioning of the printing apparatus that occurred during production thus can be remedied by the use of a corresponding sensor circuit board and an associated software version. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a portion of a printing apparatus in accordance with the invention from the rear left in service mode, with the printing carriage in the sealing position and with a transmitted light barrier that is activated by the printing carriage. 
         FIG. 2  is a plan view of the sensor circuit board for an apparatus variant B. 
         FIG. 3  shows the circuit arrangement with a photoelectric barrier according to the invention. 
         FIG. 4  shows the time change of the signal level curve for two different apparatus variants. 
         FIG. 5  explains the query by the controller using a flow chart. 
         FIG. 6  is a block diagram of a circuit for a sensor circuit board with two photoelectric barriers according to the invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  is a perspective view of a portion of a printing apparatus from the rear left. In the service mode of the printing apparatus, the printing carriage  24  is located in a sealing position in which a first transmitted light barrier  21  is activated by the printing carriage  24 . A vane  243  that interrupts the light beam of the transmitted light barrier  21  when the sealing position is reached is molded on the printing carriage  24 . The printing carriage  24  is mounted so as to be displaceable back and forth in the y-direction of the shown Cartesian axes on two rails  48  and  49 . A shaft  72  serves to drive the printing carriage  24  and is arranged below the rail  48 , thus counter to the z-direction. A slide bearing  245  and another similar slide bearing (not visible), as well as a shaft nut  244 , are molded on the right side wall (as seen from the rear) of the printing carriage  24 , thus on that side that is nearest the second frame wall  44  of the chassis. An additional slide bearing  246  is molded on the left side wall of the printing carriage  24  that is situated opposite the right side wall. The displaceable printing carriage  24  is thus supported at three points. The slide bearing  246  slides on the rail  49 , and the slide bearing  245  and the other slide bearing slide on the rail  48 . The slide bearings are adapted to the profile of the rails. The rails are designed as slide rails and have a rounded (advantageously circular) profile. The printing carriage  24  in  FIG. 1  is shown moved into the sealing position and can be driven in the direction of the white arrow (in the negative y-direction) into a printing position, and further into a cartridge exchange position. The printing carriage  24  moves out of the sealing position (“back”), over the printing position (“forward”) up to the cartridge exchange position (“all the way forward”), in which the aforementioned flap (not shown) is opened. 
     The vane  243  molded on the printing carriage interrupts the light beam of a second transmitted light barrier  22  when the printing position is reached. Both transmitted light barriers  21  and  22  are arranged at a predetermined interval (spacing from each other) on a sensor circuit board  20 . This predetermined interval is determined essentially by the distance of the sealing position from the printing position in the y-direction. The sensor circuit board  20  is mounted on the frame wall  44  so that it can easily be exchanged. 
       FIG. 2  shows a plan view of the sensor circuit board for an apparatus variant B. The sensor circuit board  20  has a low-pass filter between the transmitted light barriers  21  and  22  that are spaced apart from one another, with the transmitted light barrier  22  being offset by the distance Δs=2 mm in the direction of the transmitted light barrier  21  (compared to the position it would occupy on a sensor board designed for use in apparatus variant A). The increased tolerance values of the apparatus variant B are addressed by this offset. This geometric modification requires a software change. The controller is informed of the required software version with by the low-pass filter, namely by the signal delay caused by the low-pass filter. 
     Due to each of the variants of the circuit arrangement of the sensor circuit board  20 , in particular a variant imparted by the low-pass filter and the signal delay caused thereby, a predetermined software adapted to the apparatus variant can be selected and called by the mainboard processor of the controller in order to operate the printing apparatus. 
     Using a circuit arrangement (shown in  FIG. 3 ) with a photoelectric barrier, the functioning thereof is explained in detail. Two ohmic resistors R 1  and R 2  are connected in series and form a voltage divider that is connected between ground potential (L-level) and the base of a first npn-transistor T 1 , the emitter of which is at ground potential. The connection point of the resistors R 1  and R 2  forms the input of the circuit of the sensor circuit board  20 . A field programmable gate array (FPGA)  11  delivers the signal V IN  to the input via a pin P 1 . The transistor T 1  forms a first negator (inverter or NOT-element) N 1  for the signal. Its output is at the collector of the transistor T 1 . A low-pass filter TP is connected between the output and a first supply voltage Vs 1 . The low-pass filter TP is formed by the two ohmic resistors R 3  and R 4  that are connected in series and a capacitor C that has a predetermined capacitance in order to accordingly delay the input signal at the control input of a controllable switch, the input resistance of which control input is high. The switch is advantageously a field effect transistor T 1  (for example of the type SI2333DS) that can be switched on given a low level applied between L-level and H-level. The capacitor C is connected in parallel with the resistor R 4  and is connected with one terminal to the first supply voltage Vs 1 =5 V and with the other terminal to the interconnection point of the resistors R 3  and R 4 . The gate terminal of the field effect transistor is at the interconnection point of the resistors R 3  and R 4 . The field effect transistor T 2  is a P-channel accumulation-type FET. The source terminal of the field effect transistor T 2  is wired to the supply voltage Vs 1 . A photoelectric barrier LB 1  comprises a photoemitter and a photoreceiver. An infrared photodiode LED connected to the drain terminal of the field effect transistor T 2  via a resistor R 5  is used at the emitter side, which infrared photodiode LED is activated by a controller  10  via the input of the circuit arrangement of the sensor circuit board  20 . For example, the LED is switched on given an L/H level change of the signal V IN . Alternatively, it can be pulsed. Located at the receiver side is a phototransistor T 3  in a collector circuit whose collector is connected with a second supply voltage Vs 2 =3 V. The output signal V OUT  is variable depending on the state of the photoelectric barrier ( FIG. 4 ) and is tapped via an emitter resistor R 4  that is connected between the emitter and ground potential. The output is connected with the pin P 4  of an FPGA  11  that acts as an input and output circuit of the controller  10 . The photoelectric barrier LB 1  is open when the light beam of the LED is not interrupted. 
     The photoelectric barrier is closed when the light beam of the LED is interrupted. 
     The time change of the level curve for two different apparatus variants is shown in  FIG. 4 . The input signal VIN changes its level from low (L-level) to high (H-level) at the point in time t 1 . In the apparatus variant A, there exists only a slight delay for the output signal V OUTA  of the sensor circuit board  20 , which appears at the point in time t 2 . In contrast to this, in the apparatus variant B a larger delay exists for the output signal V OUTB  of the sensor circuit board  20  which appears at the point in time t 4 . 
       FIG. 5  serves to explain the query by the controller using a flow chart  100 . After the start  101 , an output of the signal V IN  with an L/H level change takes place at the point in time t 1  in Step  102 . In Step  103  a time period Δt is subsequently waited before the level is measured. In the query step  104  it is established whether an H-level is present, i.e. logic level=1. 
     If this is not the case, the apparatus variant B is present and an associated user program is loaded (Step  105 ). Otherwise, the apparatus variant A is present and an associated user program is loaded (Step  106 ). 
       FIG. 6  shows a block diagram of a sensor circuit board  20  with two photoelectric barriers according to the invention. An output of the FPGA is at pin P 1  and delivers the signal V IN . The aforementioned signal arrives at the input of a second negator N 2  via a first negator N 1  and a low-pass N 2 . Its field effect transistor T 2  operates as an impedance converter. Therefore, two photoelectric barriers (advantageously of type TCST1103) can be connected. Its output signal V OUT1  or, respectively, V OUT2  arrives at the pins P 3  or, respectively, P 2  of the FPGA. 
     The vane molded on the printing carriage—which vane interrupts or does not interrupt the beam path of the photoelectric barrier depending on the position of the printing carriage—has a geometry that can never simultaneously interrupt both photoelectric barriers. Additional signal lines for coding are not provided, nor is such a thing necessary. Only the existing circuits are necessary. Based on the realization that at least one of the two photoelectric barriers naturally remains open, independent of where the print head carriage is situated, the controller now activates a workflow control operating in the FPGA for variant detection and checks whether H-level (i.e. the “open” signal) appears with a time delay at the output of at least one of the photoelectric barriers. The light beam thus arrives at the phototransistor of the photoelectric barrier LB 1  or LB 2 , and said phototransistor outputs a signal V OUT1  or the signal V OUT2 . 
     In variant A, “open” appears immediately at at least one photoelectric barrier, which means apparatus variant A with an “old” sensor circuit board. 
     In variant B, “open” appears at at least one photoelectric barrier only after a defined time Δt, which means “new circuit board”. This behavior is achieved at the “new” circuit board via a time delay element (RC element) which only disconnects the LED current with a delay via the transistor. 
     The modified circuit of a sensor circuit board contributes to the determination of the position of the printing carriage. Molded on the printing carriage is a vane that interrupts the light beam of a photoelectric barrier when a corresponding position is reached upon movement of said printing carriage. The comparison of signal changes at the output of the transmitted light barrier is executed in a separate comparator that is realized by means of an FPGA. The FPGA is a component of the control and is connected to the output of the receiver unit. 
     Alternatively, for apparatus variants A and B, the detection of the sensor circuit board can also take place automatically in software via a mainboard processor of the controller. 
     The mainboard processor of the controller is programmed in order to load an associated user program for each apparatus variant. 
     Although modifications and changes may be suggested by those skilled in the art, it is the intention of the inventors to embody within the patent warranted hereon all changes and modifications as reasonably and properly come within the scope of their contributions to the art.