Abstract:
Apparatus for testing functionality of a printed circuit board used to control operation of a printing press, including a plurality of input switches for providing to the circuit board test input signals simulating function control signals from a printing press control input, the function control signals controlling a plurality of functions of the printing press; a plurality of test loads simulating printing press loads for receiving from the circuit board output drive signals developed in response to the test input signals; and a processor for controlling operation of the input switches and for monitoring responses of the test loads in response to the output drive signals, whereby proper functionality of the printed circuit board in response to each of the plurality of function control signals is analyzed under simulated conditions of an actual operating printing press.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]    This application is a continuation of pending application Ser. No. 10/266,621, filed Oct. 9, 2002. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Technical Field  
           [0003]    This invention pertains generally to the field of automated testing of electronic circuits. In particular, the invention provides a system for testing the functionality of circuit board controllers that control the operation of printing presses for printing high quality color images in newspapers.  
           [0004]    2. Description of the Background Art  
           [0005]    Newspaper editors and advertisers rely on modern printing presses to print color images of the highest quality in daily publications such as newspapers. The quality of printed color images is a function of the ability of a printing press to lay down with repeatable precision ink on paper.  
           [0006]    In this regard, color registration and maintenance of ink quality are the two most important factors in determining how color image reproduction appears in a publication. In modern printing presses, a Dampening, Registration and Ink (“DRINK”) controller subsystem performs these tasks. The DRINK subsystem contains application-specific circuit boards that control basic printing press functions.  
           [0007]    As a result of the continuous and intensive nature of the use of newspaper printing presses to produce a daily newspaper publication, color image reproduction quality periodically deteriorates, requiring printing press repair technicians to send out DRINK subsystem circuit boards to outside repair facilities for diagnosis and repair or replacement as a routine procedure in maintaining printing press color image reproduction quality.  
           [0008]    However, experience has shown that frequently the circuit boards sent out for diagnosis and repair either do not actually need to be repaired (e.g., where color image quality deterioration is caused by a malfunction other than circuit board failure) or fail to be properly repaired.  
           [0009]    While automatic general circuit board testing equipment is known in the art (see U.S. Pat. Nos. 4,965,516, 4,763,066 and 5,003,254 assigned to Huntron Instruments, incorporated herein by reference in their entirety), such equipment provides general diagnostics and individual point-to-point testing of multiple different circuit boards, and thus cannot test specific circuit board under load conditions experienced by the circuit boards. The simple general testing procedures employed by such equipment can lead to reduced circuit board repair success rates.  
           [0010]    Application-specific testing of assembled circuits is also known in the art (see U.S. Pat. No. 6,038,520 assigned to ATI Technologies, Inc., incorporated herein by reference in its entirety). However, such testing requires a separate application specific testing entity for each assembled different assembled circuit. U.S. Pat. No. 6,324,485 assigned to New Millenia Solutions, Inc. (also incorporated herein by reference in its entirety) discloses equipment for testing integrated circuit devices in their native environment. However, such equipment requires the use of multiple native devices coupled to a test device in a configuration that recreates a native operating environment of the test device by precise timing control synchronization among the multiple native devices.  
           [0011]    There remains a need in the art for a test system for specific DRINK circuit board controllers, wherein the test system is able to simulate actual operating conditions of a running printing press, in order to more accurately and quickly diagnose malfunctions in such circuit board controllers.  
         SUMMARY OF THE INVENTION  
         [0012]    The present invention fulfills the existing need in the art by providing apparatus for testing functionality of a printed circuit board used to control operation of a printing press, including a plurality of input switches for providing to the circuit board test input signals simulating function control signals from a printing press control input, the function control signals controlling a plurality of functions of the printing press; a plurality of test loads simulating printing press loads for receiving from the circuit board output drive signals developed in response to the test input signals; and a processor for controlling operation of the input switches and for monitoring responses of the test loads in response to the output drive signals, whereby proper functionality of the printed circuit board in response to each of the plurality of function control signals is analyzed under simulated conditions of an actual operating printing press.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]    [0013]FIG. 1 is a block diagram of a Digital Inker circuit board of a DRINK subsystem to be tested using the present invention;  
         [0014]    [0014]FIG. 2 is a block diagram of a digital input/output section of a DRINK circuit board to be tested using the present invention;  
         [0015]    [0015]FIG. 3 is a block diagram of an analog input/output section of a DRINK circuit board to be tested using the present invention;  
         [0016]    [0016]FIG. 4 is a block diagram of a DRINK and Digital Inker circuit board tester device according to one preferred embodiment of the present invention;  
         [0017]    [0017]FIGS. 5A-5C are flow diagrams of a test procedure for testing DRINK circuit board registration functions according to a preferred embodiment of the present invention;  
         [0018]    [0018]FIG. 6 is a block diagram of a test system according to a preferred embodiment of the present invention using the tester device of FIG. 4 and the procedures of FIGS. 5A-5C;  
         [0019]    [0019]FIG. 7 is a flow diagram of a test procedure for testing DRINK circuit board dampening functions;  
         [0020]    [0020]FIG. 8 is a flow diagram of a test procedure for testing DRINK circuit board ink functions; and  
         [0021]    [0021]FIG. 9 is a flow diagram of a test procedure for testing Digital Inker circuit board functions. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0022]    [0022]FIG. 6 is a block diagram of the testing apparatus according one embodiment of the invention. The apparatus includes a DRINK and Digital Inker Board test device  601 , a power supply  602 , a circuit board chassis  603 , and a PC  604 .  
         [0023]    DRINK and Digital Inker boards are placed into chassis  603 , in which they receive simulated printing press control signals from the test device  601  under control of a test program running on the PC  604 . Output signals from the boards responsive to the simulated printing press signals are sent to the test device, where they are analyzed for proper operation of the boards. PC  604  is directly connected to the circuit board chassis  603 , such that the PC  604  may send and receive signals directly with the chassis  603 .  
         [0024]    [0024]FIG. 1 is a block diagram of the main components of a digital inker circuit board for use with the test apparatus of the present invention. The digital inker board drives solenoids that meter a measure amount of ink onto an ink pickup roller of the printing press.  
         [0025]    Each printed page uses eight columns of ink, which are arranged in a unit called a page pack. The digital inker board receives via a backplane  101  of a central processor (CPU) ink density data for each of the eight columns inputted by an operator using press controls, and writes the data into address multiplexing logic  103 . The board also receives eight enable input signals for each of eight defined sections of a page, and two inputs for “color change” functionality.  
         [0026]    The digital inker board includes eight microcontroller units (MCU)  105 , and 16 4-channel output drivers  107 , each MCU receiving address signals and data signals from the multiplexer  103  via data bus  104  and address bus  106 , and controlling two output drivers in accordance with the received data signals corresponding to the MCU&#39;s address.  
         [0027]    A page is divided into what is conventionally known as a “10-side” and a “13-side.” Each pair of output drivers respectively drives one of a group of 8 10-side Near Page Pack solenoids  109 , 8 10-side Near Center Page Pack solenoids  111 , 8 10-side Far Center Page Pack solenoids  113 , 8 10-side Far Page Pack solenoids  115 , 8 13-side Near Page Pack solenoids  117 , 8 13-side Near Center Page Pack solenoids  119 , 8 13-side Far Center Page Pack solenoids  121 , and 8 13-side Far Page Pack solenoids  123 .  
         [0028]    The enable signals each enable a pair of 4-channel solenoid output drivers for a page pack. The ink density data signals set the density of ink for each column, which can be set from 0-100% density (the higher the percentage, the longer the solenoid stays energized). The color change signals activate a special function that cycles all ink solenoids at 100% density, which forces a large volume of ink through the page pack to effectively clean out any old ink from the page pack in preparation for an image change.  
         [0029]    [0029]FIG. 2 is a block diagram illustrating the digital input/output components of a DRINK board to be tested by the apparatus of the present invention. The DRINK board controls the operation of two spray bars, each containing eight solenoids. One spray bar is a 10-side spray bar, and the other is a 13-side spray bar. Each spray bar is used to spray a measured quantity of water onto a roller, which determines print quality and ink lay down characteristics. This dampening function is proportional to the operating speed of the printing press. At higher speeds, the spray bar solenoids must fire at a faster rate to maintain the appropriate water density on the page.  
         [0030]    Parallel Interface/Timer chip  208  is used to control the 13-side spray bar solenoids, and Parallel Interface/Timer chip  217  is used to control the 10-side spray bar solenoids. Each chip is provided with a 10 MHz clock  105 . Dampening Enable and Flood function input signals are provided to respective input buffers  211   a  and  211   b . Control data and address signals are inputted to the timer circuits via data bus  209  and address bus  210 . The Interface/Timer chips load count data into 8-bit counters  216   a  and  216   b , which are fed to respective latches  214   a ,  214   b , and  218   a ,  218   b , which in turn feed output drivers  215   a ,  215   b  and  219   a ,  219   b . A 2 kHz clock  212  and flip-flop circuits  213   a ,  213   b  are provided to synchronize the operation of the counters and the latches. The count data loaded into the counters by the Interface/Timer chips determines the firing rate of the spray bar solenoids and is determined in accordance with a Press Frequency input data signal received on the data bus  209 .  
         [0031]    The DRINK board also controls color registration or image positioning on the page, and controls the speed of the ink pickup roller. The registration can be moved ±0.063″ on the x-axis (called Sidelay Registration), and ±0.127″ on the y-axis (called Circumferential Registration). While the volume of ink applied to the roller is determined by the Digital Inker Board, the DRINK board controls the speed of the ink pickup roller, which is determined by and is proportional to the operating speed of the printing press.  
         [0032]    A Parallel Interface/Timer chip  201  receives a clock signal from 10 MHz clock  205 , a press operating frequency input signal at input register  203  which is buffered in buffer  204 , and registration command signals, inputted by an operator, which are inputted to input buffer  206 . The registration command signals are used to develop eight control signals that are outputted to FET output drivers  207 , which drive eight hydraulic solenoids that control four hydraulic pistons. Each piston controls a respective one of 10-side Sidelay, 10-side Circumferential, 13-side Sidelay, and 13-side Circumferential registration of the press rollers with respect to positioning on the page.  
         [0033]    [0033]FIG. 3 is a block diagram illustrating the analog input/output components of the DRINK board. A reference voltage Vref is provided to D/A converters  305  by a power supply constituted by a 5 volt source  301   a , a DC-DC converter  301   b , and a voltage reference operational amplifier  301   c . The press operating speed (frequency) input from buffer  204  is used by the Interface/Timer circuit  201  to develop 8-bit signals for the 10-side ink pickup roller and the 13-side ink pickup roller. These 8-bit signals are latched into latches  303  via data bus  209 , and converted into analog voltage signals in D/A converters  305 . The analog voltage signals are inputted to analog operational-amplifier output drivers  307  to drive 10-side ink pickup roller  309  and 13-side ink pickup roller  311 . The analog driving voltage ranges from 0VDC (at which the roller speed is zero) to 10VDC (at which the roller speed is maximum). The analog voltage levels are proportional to the operating speed of the press.  
         [0034]    Analog Sidelay/Circumferential position feedback transducers  313  provide voltage signals corresponding to the Sidelay and Circumferential registration positions. These feedback position signals are demultiplexed in demultiplexer  315  and converted to digital signals in A/D converter  319 . When the desired registration positions indicated by the command signals have been reached as indicated by the voltage feedback position signals, the solenoids are switched off by turning off the FET output drivers  207 .  
         [0035]    [0035]FIG. 4 is a block diagram illustrating the main components of the test device  601 . A 10 volt power supply  401  receives power from a power source (120VAC power) via a 24V power supply.  403  represents 12 DRINK function toggle switches, which provide simulated press control signals to the DRINK board Parallel Interface/Timer circuits  201 ,  208  and  217 . A 10V reference voltage signal is provided to A/D converter  319  by reference voltage generator  405 , and simulated registration feedback signals are provided to demultiplexer  315  by registration feedback potentiometers  407 . A frequency generator  409  provides a simulated press operating frequency to buffer  204 .  
         [0036]    DRINK board spray bar output driver signals from drivers  215   a ,  215   b  and  219   a ,  219   b  are provided to spray bar solenoid coil load simulators  411 , Sidelay/Circumferential registration output driver signals from FET output drivers  207  are received by registration solenoid coil load simulators  413 , 10-side and 13-side analog output driver signals from analog output drivers  307  are received by 0-10VDC analog output test points  415 .  
         [0037]    Digital Inker board simulated Ink Enable signals are provided to logic  103  by Ink Enable toggle switches  417 , and simulated Color Change signals are provided by Color Change toggle switches  419 . Digital Inker board output driver signals from 4-channel output drivers  107  are received by simulated Ink Pack solenoid coil load simulators  421 .  
         [0038]    [0038]FIGS. 5A-5C are flow diagrams illustrating a test procedure for the registration functions of the DRINK circuit board inserted into chassis  603 , as programmed into PC  604 .  
         [0039]    At step  501 , the PC is turned on and the diagnostics program is started. Initially, at step  502 , all registration feedback potentiometers  407  are set to the 12 o&#39;clock position. At step  503 , the registration position information from the DRINK board A/D converter  319  is displayed. For the 12 o&#39;clock position, the position information displayed should be 0+/−12. At step  504 , it is determined whether the displayed position values are acceptable. If the displayed information does not conform to the values that should be displayed, at step  505  an analog electrical failure is diagnosed.  
         [0040]    If the position information displayed is correct, then at step  506  the Circumferential Enable toggle switch of toggle switches  403  is turned on, and the position of the 10-side circumferential register is modified to +120, simulating a move of the 10-side circumferential registration 0.120″ in the positive direction. At this time, an LED for the 10-side Circumferential positive direction movement should be lighted on the DRINK board. If it is not, at step  509  a failure of the 10-side Circ.+drivers is diagnosed.  
         [0041]    If the 10-side Circ.+LED is on, then at step  509  the 10-side Circumferential potentiometer is rotated clockwise until the LED turns off. This should occur at approximately the 3 o&#39;clock position of the potentiometer. At step  510  it is determined whether the LED turned off at the correct position. If not, at step  511  a failure of the 10-side Circumferential+driver  207  or analog feedback circuit is diagnosed.  
         [0042]    If the 10-side Circ.+LED has turned off at the proper time, then at step  512  the position of the 10-side Circumferential register is modified to −120, simulating a move of the 10-side circumferential registration 0.120″ in the negative direction. Steps  513 - 517  are analogous to steps  507 - 511 , except that they test for failure of the 10-side Circumferential−driver.  
         [0043]    Steps  518 - 523  are analogous to steps  507 - 511 , except that they test for failure of the 13-side Circumferential+driver, and steps  524 - 529  are analogous to steps  513 - 517 , except that they test for failure of the 13-side Circumferential−driver.  
         [0044]    Similarly, steps  530 - 535  are analogous to steps  507 - 511 , except that they test for failure of the 10-side Sidelay+driver, and steps  536 - 541  test for failure of the 10-side Sidelay−driver. Similarly, steps  542 - 547  test for failure of the 13-side Sidelay+driver, and steps  548 - 553  test for failure of the 13-side Sidelay−driver.  
         [0045]    The dampening functions are tested as shown in FIG. 7. At step  701 , the 10-side and 13-side “Damp” toggle switches  403  are turned on. This operation should cause the DRINK board spray-bar output drivers to output solenoid firing signals (at a rate determined by the setting of the frequency generator  407 ). At step  702 , it is determined whether all of the LEDs corresponding to each output driver are firing properly. If any of the LEDs is not firing, at step  703  the corresponding spray-bar output driver failure is diagnosed. If all LEDs are firing, then at step  704  the Press Frequency Enable toggle switch is turned on and the frequency generator is adjusted to maximum output frequency. At step  705 , the rate information for dampening rate is displayed as determined from the output driver signals applied to spray-bar solenoid coil load simulators  411 . At step  706  it is determined whether the correct frequency (rate) information is displayed in accordance with the setting of the frequency generator. If not, at step  707  a parallel interface/timer circuit failure is diagnosed. At step  708 , the procedure is ended.  
         [0046]    [0046]FIG. 8 is a flow diagram of a test procedure for the Ink functions of the DRINK board. At step  801 , the 10-side and 13-side Ink Enable toggle switches  403  are turned on. At step  802  the output of the frequency generator  409  is adjusted to a predetermined frequency (such as to maximum output frequency). At step  803 , the analog output voltages from drivers  307  are measured as applied to the analog output test points  415 . At step  804 , the measured analog output voltages are checked against the frequency being outputted by the frequency generator. If the analog voltages do not properly reflect the inputted frequency, then a failure of the analog output driver circuitry is diagnosed. At step  805 , the test procedure then ends.  
         [0047]    [0047]FIG. 9 is a flow diagram of a test procedure for the Digital Inker board functions. At step  901 , the Ink Enable toggle switches  417  are turned on for the 10-side and 13-side page packs. At step  902 , output signals from respective the 4-channel output drivers are measured as applied to the Ink Pack Solenoid Coil Load simulators  421  (such as by monitoring corresponding LED indicators). If any of the output drivers fails to generate an output signal, it is diagnosed as a failure.  
         [0048]    At step  903 , the Color Change Enable toggle switches  419  are turned on and the frequency of frequency generator is adjusted to maximum rate. At step  904  the signals from the 4-channel output drivers are again measured as applied to the solenoid coil load simulators (again observing the corresponding LED indicators on the board) to determine whether the firing rate of the output driver signals is correct for the outputted frequency of the frequency generator. If not, a failure of the corresponding MCU is diagnosed, and at step  905  the procedure ends.  
         [0049]    The invention having been thus described, it will be apparent to those skilled in the art that the same may be changed in many ways without departing from the spirit and scope of the invention. Any and all such modifications as would be obvious to those skilled in the art are intended to be encompassed by the following claims.