Classifications

• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
  • G03B27/00—Photographic printing apparatus
  • G03B27/72—Controlling or varying light intensity, spectral composition, or exposure time in photographic printing apparatus
  • G03B27/73—Controlling exposure by variation of spectral composition, e.g. multicolor printers
  • G03B27/735—Controlling exposure by variation of spectral composition, e.g. multicolor printers in dependence upon automatic analysis of the original

Definitions

• a microfiche appendix comprising 2 microfiche and a total of 89 frames of software coding forms a part of this specification by reference hereto.
• the invention relates to a printing apparatus and process pursuant to which a light sensitive material such as color print paper is exposed to primary color lights, red, green and blue, through flats to simulate the desired printing ink colors of cyan, magenta and yellow. More specifically the invention is directed to an apparatus in which a single light sensitive material is exposed to the three primary colors through flats or films to obtain a composite color layout for proofing pur- poses so that the various positions and content of color produced by the flats can be proofed to be sure that an accurate composite color layout will be created from the flats.
• the disclosed proof light is a unique source of lighting with the objective of correlating log exposure values with the colors desired in a color proof.
• the objective is to make such proofing a rapid procedure with no more than ten seconds required for an exposure of a color and with no more than one exposure required for each color on the proof.
• the proof light provides a phase-controlled, multi-color light source involving red, ' green and blue spectral values .
• a controlled manipulation of the three lights, with blending of the lights in a mixing chamber, creates a light source for exposure of the proof with a pre-determined color of light determining the color values of the proof.
• the merged light created from varying inten ⁇ sities of red, green and blue light, is projected through a one-half inch (1/2") source to a 45° mirror.
• the concen ⁇ trated light is re-directed and distributed with light adequate for a 40 by 40 inch proof.
• a shutter control is provided for accuracy of exposure.
• the light is directed through a neutral density inverse cosine attenuator to create a perfectly uniform exposure over the entire proof.
• Spectral values of red, green and blue are measured and controlled by photometers.
• Three narrow bandpass filters are used that eliminate contamination of light experienced with broad band transmission filters. The result is optimum color values in proofing.
• This is an extraordinary flexible yet controllable light source.
• Logarithmically controlled illuminance makes controlled exposure of proofs understandable in terms used throughout the color industry. Entries are in log exposure with a remarkable correlation of value to the color in the proof. This results from the linear relationship between the logrithmic control and the color response of the proof paper. Added to this is the phase-control feature of the light. Unlike ordinary exposure lights, the light has a fixed exposure time and modifies intensity of the lights logarithmically. There is no reciprocity failure problem. The colors of the proof will reflect accurately the programmed color of the light source.
• the color palette of the light is operator pro ⁇ grammed.
• An insert pocket holds reference for nine programs with six colors each.
• Pre-programmed exposures for major accounts may be stored and totally recalled with simple pressure on the selected number.
• Programs for up to ten emulsion speeds may be entered and stored for modification of any of the color programs.
• Emulsion speed is in logarithmic value. Compensation for added overlay densities is keyed in by the operator. Included in the operating program is an automated draw-down of vacuum to assure full contact before exposure begins to simplify necessary action in the darkroom environment.
• the console is designed for accurate and rapid entry of color and emulsion programs.
• the console is designed to provide a flat surface for easy and secure positioning in the darkroom.
• the message display panel is angled for easy reference. Underlying the surface of the panel is a carbon shield to protect the circuitry from static electricity constantly present from the placing and lifting of films.
• the surface is a smooth membrane with resistance to wear and with easy movement of fingers over the surface. All keys have a phosphorescent backing for easy-to-see use. The LED lighting is easily read but will not expose the proof.
• Console designed for easy positioning in darkroom.
• Narrow bandpass filters for clarity of color and freedom from contamination of color value.
• Mixing chamber for blending of red, green and blue for specific spectral values.
• 45° angle mirror which will reflect light to a 40 by 40 inch proof with light at 8 foot height and frame at 32 inches.
• Figure 1 is a perspective view of the light box which integrates and measures the intensity of the red, green and blue lights which are used for exposing the emul- sion through the various flats. The view is partially broken away to show the interior of the light box showing the lamps, the lamp partitions, the integration chamber, the 45° mirror, the photodiodes with associated circuitry which is used to contro] the light sources and the shutter and the controlled apetture obtainable with the light box.
• Figure 2 shows the spectral sensitivity curves of a typical emulsion such as color print paper. Also shown is the spectral response of the narrow bandpass filters which eliminates contamination by nonselected colors.
• Figure 3 shows the cross hatched color grids which are used to determine recipes for recreating colors. Each grid may be created from two of the three primary colors from 0.0 to 2.0 density.
• Figure 4 shows the operator console and various control keys used in connection with the invention.
• Figure 5 is a schematic diagram of the photometer board.
• Figure 6 is a schematic diagram of the displays and keyboard used in the operator control.
• Figure 7 is a schematic diagram of the master board containing the microprocessor and logic components.
• FIGS 8 through 14 are flow diagrams of the software used in connection with the invention. DESCRIPTION OF THE PREFERRED EMBODIMENT
• FIG. 1 Shown in Figure 1 is the proof light 30 of the instant invention. If suspended from an 8 foot height or ceiling, it is designed to project light to various size proofs up to a maximum of 40 x 40 inches contained in a vacuum frame (not shown) having a 34 inch height.
• the integrator 40 or light tunnel has a neutral interior surface and interposed between each lamp and the integrator is an infra-red filter 41 and a very narrow band color filter 42 to produce a red, blue or green light source.
• the spectral response of representative narrow bandpass filters are shown in Figure 2 having a bandwidth of ten nanometers for blue, eighty nanometers for red and thirty nanometers for green. Such filters are commercially available from the Omega Corporation.
• the use of a very narrow band filter 42 eliminates the effect of overlap of spectral response of the emulsion. It also enables the intensity of the lamp to be maintained since only a very narrow band of response is selected to essentially negate the differences in response between a lamp that is heating up, cooling down, aging or the like.
• a diffuser 44 is provided at the outlet of the light mixer or integrator.
• Three photodiodes 46-48 are preferably attached to the filters to detect the variable intensity of the lamps 32-34.
• the diodes 46-48 can also be provided with encapsulated red, green and blue filters and be placed adjacent the diffuser 44 or penetrate into the interior of the integrator 40 for the same purpose.
• the light is directed onto a 45° mirror 49 to project it onto the frame.
• a shutter mechanism 60 is provided, shown in Figure 1.
• the shutter 61 is operated by a rotary solonoid 62 and software to be discussed below.
• a neutral density filter 65 which is a halftone pattern- laminated in plastic which has been exposed to accommodate the acceptance angle and cosign law of the film and for the fall-off of the light.
• the attenuator 65 has a higher density in the center of the plate and a lesser density around the outside periphery of the plate so that the intensity of the light which falls upon the film is substantially uniform.
• Attenuator below the attenuator are four plates 51-54 which are slideably provided in slots to provide a controlled aperture. In this manner, light directed from the light box 30 towards the vacuum frame will be directed solely to the vacuum frame and will not affect the exposure by bouncing off the operator's shirt, the walls and the like.
• Shown in Figure 4 is the operator console 90 which provides the user with an interface to the system.
• Numeric keys 93 on a key pad 94 and memory portion 96 as well as cper.tor function keys, speed 101, cycle 102, start 103, clear 104 and program 105 are phosphorescent to enable the operator to see the keyboard 90 with a minimum of light being emitted to affect the emulsion.
• Red, low power LED displays 110 are also used to identify the film, memory being accessed, the program position i.e. which flat is being exposed, and the like and the last numeric entry.
• the console 90 is structured so that the LED displays 110 are angled away from the film and further shield the key ⁇ board displays 93, 96, 101-105 to be sure that the console go does not create a light source which might affect the exposure.
• a carbon anti-static layer 130 is interposed between the surface layer 129 of the console 90 and the key pad contacts to protect from static electricity since movement of overlays and plastic sheets during the exposure process creates large amounts of static electricity.
• a photodiode 46, 47, 48 is positioned immediately adjacent each of the red, green and blue narrow band filters 42 to detect the amount of light which is passed through the filter 42 into the integration chamber 40.
• the current through the diode is directly proportional to the light intensity.
• Current from each diode 46-48 is connected to a log amplifier U1-U3 such as that manufactured by Intersil Corporation and -9- designated 8048.
• a reference current on pin 16 Also connected to each log amplifier U1-U3 is a reference current on pin 16. The reference currents are used to balance the dominance of the colored light from the lamps 32-34.
• the output of the log amplifiers are logarithmic and are preferably connected to three CMOS operational amplifiers U4, U4 and U5 which buffer the signals so that the switching transients of the voltage to frequency converters U6-U8 do not affect the output.
• the output of each operational amplifier U4, U4 and U5 are connected to a national semiconductor LM 331 voltage to frequency converter U6-U8.
• Also connected to the voltage to frequency conver ters U6-U8 are offset controls, R8, RIO and R12 and gain controls R13, R15 and R17. These controls are set during calibration of the machine to be sure that the slope and offset of the light sources match the logrithmic scale. Plus and minus twelve volt power supply regulators are also shown in Figure 5.
• the alphanumeric displays 110 across the top of the console 90 are created with the use of five Litronic four character alphanumeric displays, U1-U5, manufacturer's designation DL 3416.
• a four by eight keyboard array 95 is also shown which is sequentially multiplexed to determin key depressions. All operator controls 93, 94, 96, 101-105 are connected to the keyboard array 95.
• Operation of the display 110 with the three of eight decoder U6 involves three inputs.
• the display 110 to be activated is sent by a three bit binary code on inpu lines A0, Al and A2.
• Decoder U6 outputs Y0-Y4 select one of the five LED display chips 110.
• the alphanumeric characters to be displayed are connected to the displays in ASCII code on input lines B2-B8. Input B0-B1 are used for addressing.
• a write strobe is connected to input pin 9 of the alphanumeric display chips U1-U5 to enter the character.
• the three to eight decoder U6 is also used to multiplex the keyboard 95 when the displays 110 are not being selected or run.
• the binary input A0-A2 is connecte to the eight rows of the keyboard array on outputs Y0-Y7 of the three to eight decoder U6 and a low signal detected in the columns of the keyboard 95, on lines A3-A6 identify in conjunction with the input, which key is depressed.
• bits B0, Bl are used with binary code to select whic character is going to be displayed and the six bit ASCII code is used to identify the particular character.
• the unit preferably utiliz a Motorola 6803 microprocessor U4. Control signals are connected to the input or left side of the microprocessor
• micro ⁇ processor U4 On the output side or right hand side of the micro ⁇ processor U4 are the multiplexed, data and address lines.
• the microprocessor U4 sequentially cycles addres and data bits.
• the appropriate address to be accessed is connected from output lines A8-A15 through a demulti- ple ⁇ -ar or latch U5.
• the address bits are followed by data bits on output lines D0-D7. Consequently, on microprocess U4 cycles the address is latched and the data is connected to he data bus on the subsequent cycle of the micropro- cessor U4.
• On the input or left hand side of the micropro ⁇ cessor is a four megacycle clock crystal on pins 2 and 3 followed by an input referred to as nonmaskable interrupt (NMI).
• NMI nonmaskable interrupt
• the external IRQ input On pin 5 is the external IRQ input. This can be connected to a color densitometer (not shown) and used to receive voltage to frequency pulses from the color densi tometer for the purpose of conversion to density. Alterna- tively, the densitometer can be connected to pins 23 and 24 of the Serial Communications Interface (SCI) input, U8. It should be noted that with the components shown five interrupt requests (IRQ signals) are available, one external IRQ used for color densitometer, two microprocesso U4 internal timer interrupts, one of which is used as shown in Figure 14, and two communications interrupts.
• SCI Serial Communications Interface
• Input pins 8-10 are used for mode selection and input pins 13 through 15 are used for a densitometer input which can be used instead of operator input on the key pads 95.
• the nonmaskable interrupt connected to pin 4 is handled immediately by the microprocessor U4 every time it occurs.
• the nonmaskable interrupt is driven by a zero crossing circuit consisting of a CMOS operational amplifier U3-A which receives the 120 volt 60 hertz signal from the line. Using input dividers and gain control, the input signal is shaped into a 60 hertz square wave.
• the output of the operational amplifier U3-A is connected to two integrating capacitors C22 and C23. The charge cycle of both capacitor C22 and C23 are clamped at their 50% charge using diodes CR10 and CR11.
• a delay circuit 122 Also included in the reset circuitry is a delay circuit 122.
• the delay circuit 122 holds the reset line low until power is fully up. The delay is controlled by the amount of charge on capacitor C17 which is delayed by the RC time constant of resistor R21 and capacitor C17.
• the 6803 microprocessor U4 is reset and the system is at full power operation.
• Ports 20-22 of the microprocessor U4 are used to set the operating mode of the microprocessor U4. As shown, the microprocessor U4 is operated in the expanded multiplex mode to provide an external data and address bus .
• Output Ports 10-12 are used to select up to eight different color filters in the densitometer input.
• the densitometer switches through broad band and narrow band red, green, blue and visual filters.
• the broad band filters are used to read the color originals so no information is missed.
• the produced color in the proof is read with the narrow band filters.
• Ports 14-17 on pins 17 through 20 control the peripheral components of the system. This includes an outlet which controls the room lights which are switched off before an exposure is begun.
• the vacuum pump for the vacuum frame is also switched on before starting an expo ⁇ sure.
• a fixed time period is proVided to enable enough time for the vacuum to be drawn before the exposure has begun.
• a shutter control is also connected to the micropro ⁇ cessor on port 16, pin 19, so that the lamps within the light box come up to an established level before the shutter opens for exposure and a fixed exposure time interval is also provided to control reciprocity error.
• a watchdog circuit Ul discussed below, is connected to port 17 through a flip-flop U14.
• Chip select includes the RAM, the ROM, the counters and the input output port U8.
• the input output port, U8, Motorola chip designa- tion MC 6821P under processor U4 control drives the display 110 and keyboard 95.
• Lines A0-A2 address the 3 x 8 decoder U6 and lines A3-A6 constitute the key return from the columns of the keyboard 95.
• Connected to line A7 is a beeper 132 associated with the key pad so that a beep is made on -.ch key stroke of the key pad.
• outputs B0-B7 control the alphnumeric display with output CB2 providing the write strobe.
• Counter Ull Motorola designation MC 6840 is the photometer counter. Initially the count is set at hex count FFFF and as the photometer pulses come in they decrement the counter. After the photometer pulses are read, the FFFF value is subtracted from the count to yield the actual photometer count.
• the microprocessor U4 reads the counter Ull via the address and data bus and resets it to FFFF. The photometer input is connected to the counter on J7.
• Counter U12 also designated 6840 by Motorola, which is interconnected with a quad-output flip-flop U14, Motorola chip designation MC 4043, is the phase control counter or phase timer. Three counters are used in the counting chip Ull and three corresponding flip-flops are used in the flip-flop chip U14.
• the count which corresponds to the time that each lamp is to be deenergized is loaded into the counter Ull via the microprocessor U4, address and data lines. In other words, on a one megacycle clocking rate, a count of one would be loaded if the lamps were to be fully energized for a full half cycle of the 60 hertz lamp voltage.
• 8333 counts would be loaded if a lamp was to be fully de-energized during a full half cycle of the 60 hertz power to the lamp.
• a relatively high count is initially loaded into the counters so that the lamps can be warmed up.
• an actual count is loaded into the counters based on the data input by the operator and the actual intensity of the lamps as measured by the photo ⁇ meters. The initial warm up of the lamps can take place while the vacuum is being drawn on the vacuum frame.
• the flip-flops are set at the zero crossing, causing the counter Ull to begin counting.
• each counter times out, that is, reaches the prescribed count the corresponding flip-flop is reset causing it to emit a pulse on the R0, RI or R2 outputs each of which is connected to a separate driver U2A, B and C and through the driver U2-A, B and C to a transformer T-. T. T_ to fire a triac MAC 1-3 which causes the respective red, green or blue lamp to be energized during the remaining portion of the 60 cycle power wave form.
• a watchdog circuit Ul is also provided with tran ⁇ sistors Ql and Q2.
• the watchdog Ul must be reset every 10 milliseconds by the microprocessor U4, to be sure the microprocessor U 4 is operating correctly.
• the watch ⁇ dog Ul is cycled or reset, its output goes high to turn on the transistor Ql which supplies the voltage to the transformers T3-T5. If the watchdog Ul does not recycle, no power can be connected to the transformers T3-T5 and consequently, the triacs MAC 1- MAC 3 cannot be fired and the system will shut down until the microprocessor U4 is shut down, cleared and begins operating correctly.
• a primary objective of the invention is to mini- mize the amount of time and effort required by the operator to expose a single light sensitive emulsion such as Kodak Ektacolor Plus Paper, Fuji Color Print Paper, Agfa-Geavert Color Print Paper and the like, for position and color acceptance proofing and evaluation of complex process color work.
• the invention allows a single exposure for each of the four flats normally used for four color work. The operator may add cut and fold lines and a background hue, two additional flats, again each requiring a single expo- sure, to complete the job.
• the invention must be programmed for each flat and each desired shade of the secondary colors. Consequently, the memory of the device is currently structured to accept nine different job condi- tions. It will be clear to those skilled in the art that more or less job memories can be established.
• the actual color that is the component values of the colors are determined with an input densitometer which can be connected to input pin 5 of microprocessor U .
• Color control is achieved with the selection of broad band filters from output ports 10-12 as explained above.
• An alternative method is available when a color densitometer is not used.
• Th- ' .s procedure uses color grids 201, 202 which are shown j i Figure 3.
• a piece of film is exposed with a red light only creating a gray scale that goes from zero to 2.0 density in .05 density incre- After the red exposure is completed, the film is rotated 90° and exposed with green light. This creates a large square color pallet 201 which varies from no expo ⁇ sure to maximum exposure of the two primary colors. Similar grids are created with green and blue exposures and red and blue exposures.
• a black exposure 202 is similarly created in a single dimension.
• the red light will give the cyan color and the green will produce magenta.
• the center may be excised from each color wedge.
• the actual color that is to be reproduced may be determined by simply .laying the appro ⁇ priate grid over the color to be proofed. The grid is shifted until the best color match is obtained between the original and grid. Assuming a maximum exposure of 250 to create the grid if the color match occurs at .2 red and .4 blue, cc values of 230 red and 210 blue can be used for the recipe for the actual exposure for proofing purposes. Other methods will be obvious to those skilled in the art. For example, a small hole may be punched in the color sample to be matched.
• the displays 110 When the power switch is turned on, the displays 110 should be blank. This display condition is referred to as "stand-by". In stand-by the proof light 30 is ready to accept commands. There are four basic commands, program 105, memory number 96, speed 101 and clear 104. Other accessible controls as shown in Figure 4 is the start button 103, the cycle button 102 and the numerical keys "93. To execute basic commands the appropriate keys 95 are depressed while in stand-by.
• the software routines are executed with a number of flags, counters and regis ⁇ ters.
• the flags used in the software routines include program, exposure, clear, done, memory, speed, calculate and vacuum.
• the counters are a delay counter, color counter and a flat counter.
• the registers used are for the red exposure, the green exposure, the blue exposure, binary coded decimal (BCD), the memory number being programmed or accessed and the film number. These are typically displayed with the LED displays 110 at the top of the console.
• the program key 105 is depressed, the start key 103 is depressed and using the numerical keys 93 the number of seconds of vacuum delay are entered.
• depression of the program key 105 clears a number of flags 312, sets the program flag 315 and causes the LED display 110 to display "PRG" 317 and returns to the scan routine 319.
• depression of the start key causes the software to check to see if the program flag is set 322. Since it is, the vacuum delay routine is initiated 325. The display 110 will read ' "PRG VAC DLY" 327 and an old value will be recal l ed and displayed if it exists 328. Again, the software will return to the scan routine 329.
• depression of the numerical keys 93 determines if the speed flag is set 332, the calculation flag is set 334 or if the program flag is set 336. Since it is, the number is converted to binary coded decimal and stored as the time for the vacuum delay 338 which was discussed above.
• the program control 105 is depressed followed by the speed key 101.
• the central display 110 will say "PROG FILM NO.”.
• a film identification is then entered using the memory keys 1-9.
• the left hand LED display 110 will now show the emulsion number entered.
• the central display 110 will say "PRG SPD RED”.
• the red exposure should then be entered using the numerical keys 93 and the value entered will appear in the right hand display 110.
• the software is origi ⁇ nally in the scan routine of Figure 14. Depression of the program key sets the program flag 315 as described in connection with Figure 13. Referring to Figure 8, since the program flag is set 341, depression of the speed key
• the display 110 will now say "PRG SPD GRN”.
• the green exposure required is then entered and the cycle key 102 is again depressed to enter the blue exposur .
• the color count 356 will be incremented and since the color is less than four 356 the new color, green, will be displayed 358 and the software will return to the scan routine 359. This process will be repeated for the three primary colors.
• the color will be equal to three 356 but less than four 362 so the display will read "EXPOSE TEST OBJECT" 364 and the subroutine will jump to "GET READY" 366.
• the control is now ready to expose a test scale image.
• the start key 103 is depressed.
• the vacuum delay will be initiated. A minimum of three second delay is necessary for lamp war up. At the end of this delay the shutter is activated for exposure.
• any override value will be recalled and displayed 373. If no override is present, the display should normally read 0000.
• An override value can be change or entered at this time if desired using the numerical keys 93 of Figure 10. For example, to compensate for an overlay support which has a density of .05 enter 5. All exposures can be increased by .05 density. The lights will then be turned off 378 and the software will return to the scan routine.
• the start key 103 shown in Figure 8 is depressed.
• the vacuum delay is initiated 379 and a delay or exposure time is entered 382.
• the shutter is activated for exposure.
• timing of the process is achieved with the IRQ timer attached to the microprocessor U4.
• An IRQ timer pulse is emitted every 10 milliseconds which decrements the key debounce 390, decrements the beeper 392 which sounds every time a key is depressed, it sets the delay or exposure to 3 seconds if not activiated and then decrements the exposure 396 or decrements the delay 397, when the vacuum delay equals zero the shutter is opened 398, if active.
• the shutter is closed 399.
• the program key 105 is depressed followed by one of the nine memory numbers 96.
• the memory numbers selected will appear in the second left hand window 110.
• the central display will say "FLAT ONE RED" and the right hand display 110 will show the expo ⁇ sure amount previously entered.
• Each exposure memory is capable of storing expo ⁇ sures for up to six flats. Each one consisting of a red, green and blue combination. For each color channel, red, green or blue, the exposure amount required as entered and then the cycle key 102 is depressed all operating in the manner discussed previously. When oycle key 102 is depressed after the blue entry, the flat number will be incremented and a new flat number will be displayed 402 as well as the next color, i.e. red, for flat number 2. In this manner, all entries can be made until all 6 flats have been programmed. Normally, all 6 flats will not be required and flat numbers not intended for use should contain zero. It is, therefore, advisable to use the clear command 104 to clear a memory prior to programming. The clear routine is shown in Figure 11 and will clear all values in any memory sequence 96 chosen.
• the offset is an arbitrary value, which can be fixed a 250 units, used to adjust for differing film speeds and to assure that the exposure remains Under the maximum expo ⁇ sure range.
• the 60 cycle interrupt shown in Figure 11 designated NMI 411 then causes the photometer routine to read the photometer count and when the count value equals the calculated value, the actual log intensity of the light has been achieved. Because a fixed exposure time is used, the amount of illumination is determined by the phase con ⁇ trol of the lamps so that each lamp is energized only during a portion of each 60 cycle of the 60 hertz operating voltage.
• the calculations are based on the recipe values, the entered red, green and blue exposures for each color memories 1-9 and flats 1-6 for each.
• the recipe value is converted to hexidecimal 412 and the film speed is added to that value 415 and the offset is subtracted from that value 418 to create the target red, green and blue values to be mixed in the light chamber.
• the calculate routine 411 cycles through all three colors 421 and when all three colors have been calcu- lated the photometer is set to begin 425.
• the photometer value is read 430. Since the photometer counter Ull were originally set at FFFF and the logrithmic pulse train from logrithmic amplifiers U1-U3 decrements the counter Ull, the compliment (FFFF - the counter counts) is derived 440. Its difference from maximum count 8333, is calculated 445. The maximum count less the photometer count is the actual log intensity of the light that has been received for purposes of the exposure. From this is subtracted the target count 450, and the present phase count 452 is added, the portion of each 60 cycle that the lamp will be energized. If the resulting phase count is greater than the minimum phase 454, that "new" phase count is stored in the counter 458. If the phase count is less than the minimum phase achievable, the minimum phase is used 460.
• the exposure time is decremented 396 until the exposure time equals the zero 470.
• the shutter is closed 399 and timing f-or the next flat 475 is initiated.
• a light sensitive emulsion has been disclosed in the preferred embodiment
• a diode array can also be used as the light sensitive medium and sensed light intensity values stored for processing.
• three lamps have been disclosed with three separate filters
• a single light source or lamp with a composite filter may be used as well.
• a three sector filter each sector big enough to accept all of the light beam, is possible.
• the composite filter would normally be- placed in the light beam so that the center of the beam coincides with the point where all three sectors join with the light being mixed in a small chamber after the filter.
• the color of the exposing light can be varied by moving the composite filter vertically and/or horizon ⁇ tally so that more or less of each of the sectors are exposed to the light beam.
• C of the exposure would thus be controlled by controlling the X-Y position of the composite filter in front of the light beam and the light intensity or density of exposure could be controlled by adjusting the intensity of the lamp or the duration of the exposure time.
• Other more mechanical and manual techniques can be used as well.

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• 1987
  • 1987-02-27 WO PCT/US1987/000422 patent/WO1987005408A1/en not_active Application Discontinuation
  • 1987-02-27 EP EP19870901961 patent/EP0258416A4/de not_active Withdrawn

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