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Controls Group Inc. |
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Controls Group Inc. |
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| The implication of this statement is that “Digital”
implies superior accuracy. Digital implies two states of existence, 1 or 0. Indeed a common light switch operates digitally; the light is on or off. Highly accurate ink control requires linear ink volume coupled with web speed, not just simply on or off. So which of the two devices is more accurate? The answer to this question can be best demonstrated by first understanding that the print zone requires a linear relationship between ink volume and print speed. Double the press speed double the ink volume, a simple straight-line function. Understanding this relationship is the key to understanding which devices on the market are the best. The CGI digital page pack delivers a linear volume of ink throughout the speed range. We do not require “ink curves”. Ink curves are used by open fountain systems to correct for the inherent nonlinear delivery of ink over the speed range. Ink curves are by nature derived by taking several image density readings throughout the speed range and then programming compensating curves (ink curves) to return the image to the correct density. Given ink curves are nonlinear, the industry has accepted that any ink metering system using curves; is by nature inaccurate. Its performance is not described by a straight-line function. As soon as you hear the term “ink curves” associated with any device, you know the system is not linear by design. Our competitor uses ink curves to “fix” the delivery of their page packs, digital maybe, but not linear. CGI requires no ink curves; therefore, by design we offer superior accuracy and simplicity. The side-by-side comparison below demonstrates the clear and
significant differences between the CGI digital page pack and the
competitor's gear/shuttle valve page pack. Below the comparison chart
are links to flash animations showing in detail how each page pack
works. |
| CGI page pack uses a linear ink volume versus press speed relationship. CGI page packs do not use an ink curve, therefore, CGI page packs deliver ink more accurately over the entire speed range. | The competitor requires a programmed ink curve to correct for the page pack non-linear ink delivery versus press speed. This ink curve introduces errors into the system resulting in less accurate ink delivery. |
| CGI uses a positive displacement piston and a 400 step per revolution to control ink delivery volume. Volume regulation of less than 0.0013 oz. per step achieved at maximum press speed. | The competitor uses a shuttle valve to divide the volume of ink from the regulating gear set. Small image converge is limited by shuttle valve's mechanical shifting speed. Minimum regulated ink volume remains unpublished. |
| CGI does not require an air supply, only
electrical power, 480 VAC, 3 phase. No air supply required. |
The competitor requires a regulated, filtered
and oiled supply of air for operation. Customer must supply air. |
| CGI mounts all motors and drives within the
page pack. No external drive is needed. |
The competitor requires a remotely mounted AC Drive System to control each of the page pack Pack Motors. |
| CGI uses a stepping motor to direct drive one piston per column. Eight motors directly driving eight pistons. | The competitor uses nine closely matched ink regulating gears, eight rotating valves, eight air driven shuttle pistons, eight electric-to-air solenoids, with numerous seals for one page pack. All these assemblies are driven via the AC Pack Motor noted above. |
| CGI operates accurately from an ink supply pressure of 25 to 45 PSI. | The competitor requires 40 PSI +/- 5 PSI for proper operation. Accuracy of ink flow diminishes with pressure outside this narrow range. |
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