Peripheral Imaging Corporation PI331MC-DR 300DPI CIS Two Level Digital Output Module Engineering Data Sheet ™ Key Features • Light source, lens, and sensor are integrated into a single module • 11.8 dpm resolution, 89 mm scanning length • Up to 600 µsec/line scanning speed, with 2 MHz pixel rate (See Table 3, Note 3.) (Other speeds are also available) • Wide dynamic range • Two-Level Tracking Digital Output (“Dynamic Threshold Digitizer”) • Red light source 660nm (Other colors are available) • Compact size ≅ 13 mm x 25.6 mm x 102 mm • Low power • Light weight General Description The PI331MC-DR is a contact image sensor, CIS, module with an additional on board circuit that digitizes the analog pixels from the CIS image sensor to a “backgroundtracking”, two-level digital output signals. It is based on CIS module, the PI305M-A6 manufactured by PIC, but with a shorter read length of 89 mm. Hence, its performance is equivalent to the PI305M-A6 that uses MOS image sensor technology to gains its highspeed performance and high sensitivity. The PI331MC-DR is suitable for scanning documents with width of 89 mm and with resolution of 11.8 dots per millimeter. Its has a broad applications, but specially designed for the following areas: • Where data compression is required, such as in data transmissions. PAGE 1 OF 9 - PI331MC-DR, 11-8-00 • Where component pin-out count must be kept to a minimum. The background-tracking-digitizing circuits in the PI331MC-DR have been referred to as the “dynamic threshold” two-level A/D converter. For the purpose of describing the module’s characteristics this “dynamic threshold” processing circuit shall herein be referred to as the “tracking digitizer”. Module Description GLED LED LED LED LED LED LED LED LED VLED ROD LENS 1054 PHOTO SENSORS 1 2 3 4 5 1055 1056 ---------------- VIDEO LINE VN(-V) VDD (+5) SHIFT REGISTER GRD BUFFER VIDEO AMP CP SP TRACKING DIGITIZER DIGOUT GRD Figure 1. PI331MC-DR Module Block Diagram. The PI331MC-DR module consists of 11 sensors that are cascaded to provide 1056 photo-detectors with their associated multiplex switches, and a digital shift register that controls its sequential readout. Mounted in the module is one-to-one graded-indexed micro lens array that focuses the scanned documents to image onto its sensing plane. A buffer amplifier amplifies the video pixels from the image sensors and passes them to analog digitizing circuit, where video pixels are converted to digital signal and passed to output of the module. See Figure 1, the block diagram of the PI331MC-DR module. Illumination is by means of an integrated LED light source. All components are housed in a small plastic housing with a cover glass which acts as the focal point for the object being scanned and protects the imaging array, the micro lens assembly, and the LED light source from dust. The pictorial of PI331MC-DR cross section is shown in Figure 2. PAGE 2 OF 9 - PI331MC-DR, 11-8-00 DOCUMENT SURFACE GLASS WINDOW ROD LENS MODULE HOUSE LIGHT PATH D LE R BA SENSORS PCB Figure 2. INSIDE PICTORIAL OF THE MODULE I/O to the module is a 8-pin flex cable connector (See I/O Connector, under Specifications) located on one end of the module. The connector is on the top of the module with the glass window facing down and it is located on the opposite side of the module. See the Mechanical Housing under Mechanical Structure. Circuit Description and Operation See Figure 3 a simplified block diagram of the analog tracking digitizer. Fundamentally, the tracking digitizer transforms the signal output from a CIS module existing on the IMAGE PIXELS TWO LEVEL COMPARATOR FROM THE CIS DIGITAL OUTPUT REFERENCE LEVEL GENERATOR FIGURE 3. ANALOG SIGNAL REFERENCE GENERATOR AND A SINGLE BIT COMPARATOR market today. It takes the analog signal from the CIS section of PI331MC-DR and derives a tracking background reference signal. Then this reference is compared against the output signals from the CIS section. The resulting signal from comparison produces a twolevel digital signal that is high when the pixel signal is brighter than the background and remains at zero as long as the signal is darker than the background signal. PAGE 3 OF 9 - PI331MC-DR, 11-8-00 Figure 1, PI331MC-DR block diagram depicts the two basic circuits, the CIS (image sensors and video amplifier) and the tracking digitizer. In the CIS section, the module has 11 serially concatenated PI3012A image sensors, accordingly, the image sensors will span one scanning-read line width that is 11 sensor times 96 pixel elements/sensor, or 1056 pixel elements. In operation the module produces the analog image pixel signals that are proportional to exposure on the corresponding picture element on the document (the video signal) then passes the signal to the tracking digitizer. In turn, the digitizer processes the analog image pixels to digital image pixels. The analog image pixels, at test point TV, are separated into two signals. One generates the reference signal and the other remains unmodified. These unmodified image pixels are applied to one of the input of the comparator. The reference signal is applied to the second input of the comparator. The results of the comparison are the digital image pixels. This digital output is produced in two levels, determined by the difference between the background reference signal and the analog image pixels. A digital pixel output of value “one” represents the analog image pixel that is brighter than the background and digital pixel level of value “zero” represents the image pixel that is darker than background. Specifications I/O Connector The table of pins and their functions are listed in Table I, Pin Configuration. Pin Number 1 2 3 4 5 6 7 8 Symbol DIGOUT Vdd (+5 V) Vn (-10 to -5V) SP GRD CLOCK GLED VLED Names and Functions Digital Video Output Ground; 0 V Negative power supply Start Pulse for the shift register Ground; 0 V Clock for the shift register Return for the LED light source Power in for the LED light source. Table 1. Pin configuration The connector is a 8-pin 1-mm surface mount flex input, Molex 52207-0890. Inputs: There are five inputs: • Clock is on Pin 6 of the I/O Connector. This is main clock input into the CIS Module. • SP is on Pin 4. This is the start clock input to the CIS Module. PAGE 4 OF 9 - PI331MC-DR, 11-8-00 • VDD is on Pin 2. This is a + 5 Volts supply. • VN is on Pin 3. This is a (– 10 to –5) Volts supply. • VLED is on Pin 8. This is a +5 Volts supply for the LED light source. Note: Power return for the LED light source is GLED on Pin 7 and the ground return for the CIS modules is pin 5. Video Output: DIGOUT is on pin 1 of the I/O connector. This is the digital video output from the CIS module. Reflection off the dark target produces a digital signal of “0” level, while the white reflection off the white target produces a digital level of “one”. The amplitudes of the white and dark are listed in the table below: Electro-Optical Characteristics (25° C) Table 2. Electro-optical characteristics at 25° C. Parameter Symbol Number of photo detectors Pixel to pixel spacing Line scanning rate Tint(1) Parameter 1056 84.7 600 Units elements µm µsec Clock frequency Bright output Dark output 2.0 >3.2 <0.8 MHz Volts Volts f Digital Video Output Signal Note @ 2.0 MHz clock frequency (1) The Tint is specified with a 2.0 MHz clock frequency. In operation the time constants in the reference generator is set to match the initial exposure time, hence the time constant will determine the optimum integration time. Note the integration time is also a function of the clock frequency. Accordingly it is highly recommended that the parameters be factory adjust for the specific applications. Table 3. Recommended Operating Conditions (25 °C) Item Power Supply Input voltage at digital high Input voltage at digital low Clock frequency(1) Clock pulse high duty cycle Clock pulse high duration(2) Symbol Vdd Vn. VLED Idd Ivn ILED Vih Vil f Clock Min 4.5 -10 3.5 21 9 25 Vdd-1.0 0 1.75 25 Mean 5.0 5.0 22 10 160 Vdd-.5 100 PAGE 5 OF 9 - PI331MC-DR, 11-8-00 Max 5.5 -5 5.5 25 12 200 Vdd 0.8 2.25 Units V V V mA mA mA V V MHz % ns Integration time Operating temperature 600(3) Tint Top 25 50 ms 0 C Note: (1) The clock frequency and the integration times must be fixed at the factory. However, it will tolerate a slight deviation in clock frequency and integration time as indicated by the minimum and maximum clock speeds. (2) Clock pulse high is specified at 2.0 MHz at 25% duty. (3) The Tint is specified with a 2.0 MHz clock frequency. In operation the time constants in the reference generator is set to match the initial exposure time, hence the time constant will determine the optimum integration time. Accordingly it is highly recommended that the parameters adjusted at factory for the specific applications. Switching Characteristics (25°C) The switching characteristics for the I/O clocks are shown in Figure 4, Module Timing Diagram. The timing parametric values and their symbols are given in the Table 4. to tw CP tprh SP tdh tds tdl Vanalog tsh tddl tdodl Digout MODULE TIMING DIAGRAM FIGURE 4. Table 4. Switching Parameter and Timing Symbol Definition Clock cycle time Clock pulse width Clock duty cycle Prohibit crossing time of Start Pulse Data setup time Data hold time Symbol to tw Min. tprh 100 25 15 tds tdh 20 20 Typical 0.50 PAGE 6 OF 9 - PI331MC-DR, 11-8-00 Max. 50 Units µs ns % ns ns ns Signal delay time Signal settling time Digital Signal Delay Digital Signal Off Delay tdl tsh tddl tdodl 50 120 ns ns ns ns 60 300 Table 5 Absolute Maximum Rating: Parameter Symbols Power supply voltage Vdd Idd Vn In VLED ILED Vih Vil Input clock pulse (high level) Input clock pulse (low level) Maximum Rating 10 50 -15 30 6.0 250 Vdd – 0.5 -0.8 Units V mA V mA V mA V V Note: These are absolute maximum parameters and should not be used in operation. Table 6 Operating Environment Operating temperature Operating humidity Storage temperature Storage humidity Top Hop Tstg Hstg 0 to 50 10 to 85 -25 to+75 5 to 95 0 C % 0 C % Setup and Adjustments The Clock Rate and Integration Time: This was factory set to a specific application. See note 1 under Table 2, Electro-optical characteristics at 25° C. The clock frequency was set to 2.0MHz. The total integration time was set to 600 µsec. The Required Power. The required power is slightly greater than the specified values in Table 3. Circuit Power: Positive Supply: Negative Supply: LED Power: +5 Volts @ 25 mA -10 Volts @ 15 mA +5 Volts @ 180 mA PAGE 7 OF 9 - PI331MC-DR, 11-8-00 Adjustments General Location of Test, Adjustment and Monitor Points BACK SIDE OF THE PCB AS VIEWED ON MODULE WITH THE GLASS WINDOW FACING DOWN. TVD TV R5 (GAIN ADJ) TR R4 (OFFSET ADJ) CONNECTOR VLED GLED PI331MC-DR PCB MONITOR AND TEST POINTS FIGURE 5. Figure 5, PI331MC-DR PCB MONITOR AND TEST POINTS, shows the pictorial layout of the controls and the tests points. These adjustment potentiometers and the test points are shown relative to the connector and to the output pads for LED light power. This is a bird’s eye view of the PCB’s backside with the glass window of the module facing down on the documents. Test point labeled TV is for the analog image pixels, just as it is produced at the output of the CIS array section, and prior to its entry into the tracking digitizer circuit. Test point labeled TR is the output of the tracking reference level from the tracking digitizer circuit. Test point labeled TVD is the digital output from the comparator. Offset adjust, R4, is a screw driver adjustment potentiometer that is accessed through adjustment hole as it viewed in figure 5. Gain adjust, R5, is a screw driver adjustment potentiometer that is accessed through the hole as it is viewed in figure 5. PAGE 8 OF 9 - PI331MC-DR, 11-8-00 There are only two adjustments: These adjustments will be pre-adjusted to the customer’s specific application at the factory, therefore, in general will not require adjustments by the user. The gain is adjusted by monitoring test point TV with a scope, adjusting the gain potentiometer, R5, until the analog image pixel levels are set to approximately 2.0 volts peak with the module imaged on the a standard white target similar to the standard white copy or typing paper. (The probe should be grounded as close to the CIS module as possible. If possibly right on the ground input lead, pin 5, of the I/O connector.) Then DC reference level is adjust by monitoring test point TR and setting the voltage to approximately 1.6 Volts by adjusting offset potentiometer, R4. Mechanical Structure e on ez v i Note: ct ina 10 All dimensions in mm. te a xim pro ap 2 ve cti 10 imum ina x m ma ne 4m zo 2 ma 5.6 xim um .0 er or 15 centnect n he o t Tof the o Two sets of mounting holes are mirror imaged on both ends. Hole = 2x2 M1.8 Top Tight Screw 8.0 14 .0 c 1mm x 8 Flex cable connector 22.00 22 .0 7.1 14.0 16.5 24 .6 Readline 6.0 24.3 6.8 25.3 FIGURE 6. Mechanical Structure Figure 6 is pictorial of the PI331MC-DR. It shows the mechanical dimensions of the housing and its mounting hole locations. The “inactive zones” are the sector without imaging sensors. ©2000 Peripheral Imaging Corporation. Printed in USA. All rights reserved. Specifications are subject to change without notice. Contents may not be reproduced in whole or in part without the express prior written permission of Peripheral Imaging Corporation. Information furnished herein is believed to be accurate and reliable. However, no responsibility is assumed by Peripheral Imaging Corporation for its use nor for any infringement of patents or other rights granted by implication or otherwise under any patent or patent rights of Peripheral Imaging Corporation. PAGE 9 OF 9 - PI331MC-DR, 11-8-00