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New On-Line Colour and Brightness Measurement and Control System
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NEW ON-LINE COLOUR AND BRIGHTNESS MEASUREMENT AND CONTROL SYSTEM M. Lehtoviita
Abstract. In recent years, the on-line measurement and control of colour and brightness has stimulated great interest in the paper industry. The monitoring and control of paper quality in the paper mill is becoming increasingly important as the capacity and quality requirements of both the paper mills and the printing houses continue to rise. The continuous on-line measurement and control system described in this paper is noteworthy for the production of even colour, the reduction of colour broke, and tne snortening of the time required for grade and colour changes.
BACKGROUND
There have been some difficulties associated with continuous measurement on a paper machine in comparison to measurement in the laboratory. The conditions in a paper machine are different from those in the laboratory in regard to temperature, vibration, and dirt, for example. In the paper mill environment electrical interference may cause difficulties in the handling of measurement signals. Also, a colour meter installed on-line cannot be in direct contact with the web. The on-line measurements are therefore taken from a single fluttering sheet of web at a distance of about 7 mm.
The wood-based industries, and especially the paper industry, dominate Finnish economic life. In 19t1I, about 4U ~O of all Finnish exports derived from this sector. As a result, large sums of money have been spent, and continue to be spent, to further the development of these industries. Of special note are the Finnish developments in the area of computer applications. In Ahlstroem's Varkaus Paper Industry, the first computer based system for monitoring and control of production was "on-line" about 1969. Later, laboratory and quality control became computer based. In its first applications, quality control included only the laboratory tests of some of the end product values. But today quality control involves a whole range of operations including the control of raw material quality and a multitude of process controls.
The possibilities for calibration in on-line measurement are limited compared to laboratory conditions. The fact that the measuring head generally is installed between the calender and the Pope limits the size of the measuring head. While this location is generally a convenient place, other measuring equipment is often already installed there.
THE 'COLOURKEEPER' COLOUR HEASURING AND CONTROL SYSTEH
At first only the measurement and control of moisture and basis weight were computer based. But today, the new micro-computer technology has opened many more possibilities to develop quality control systems for the paper industry. One such application is the continuous measurement and control of colour and brightness.
( Figure 1) The COLOURKEEPER system consists of four basic parts : - the measuring head and its mounting frame - the power supply unit - the electronic cabinet - the display unit and the keyboard
COlOUR MEASUREMENT IN GENERAL The measuring head includes lamps, optics, a filter / photo cell, and an automatic reference plate unit.
The paper industr y 's interest in continuous colour measurement systems has increased due to the demand for higher paper quality, for better optical characteristics, and for less broke. The technological advances in colour meters and their associated equipment nave also stimulated the industry's interest.
The Hunter D43 optical measuring head is used as the measuring sensor. The measuring head employs a light source comprised of two matched quartz iodine lamps. The energy from each lamp is collected and focused through
!'::'A- : ..
241
M. Lehtoviit a
24 2
separate apertures onto the specimen surface. The two opposing beams of light strike the specimen at 37° to a line perpendicular to the specimen surface. Light diffusely reflected from the specimen is collected and transformed into electrical signals corresponding to Xa, Xb, Y and Z values. The measuring head is protected from accumulating airborne dust particles by a flow of filtered air which also serves to provide the necessary cooling. The power supply unit contains amplifiers, solid state power supplies, and the output to related equipment. The regulated lamp power is also located in the power supply unit. The electronic cabinet contains micro-computer and electronics. The display unit contains a plasma-display.
INSTALLATION
or
THE 'COLOURKEEPER'
ON A PAPER MACHINE
(Figure 2) The measuring head and its mounting frame are installed on a paper machine in the manner shown in Figure 2. Riding on the mounting frame are two carriages positioned both above and below the web. The measuring head is fixed to the upper carriage while the standard plate is secured to the lower carriage. Both carriages move simultaneously and are controlled by a computer programme governing pneumatic cylinders. The measurement is taken from one fixed position on the paper web. This position is about one meter from the edge of the web. The measuring head can be moved off the paper web in case of web breaks, for servicing, and for calibration.
puter consists of an Intel b085 based CPUcard. In addition, there is a 20 Kb program memory and an 8 Kb data memory. All cards in the micro-computer are standard and can be easily changed. The extent of the electronics varies according to the number of functions and field interfaces required. To operate, the system must be energized, and a minimal amount of data is fed into the system by the operator. The following is entered from the control console : - colour value set point, variation values - pumps to be used - dye concentrations to be used - backing data - frequency of reports - grade data - time - mathematical models - controller's calibration values Part of this data is already included in a previously entered code number or grade number. However, this code number can be changed in certain circumstances. For grade changes, the code number is the least that must be given. If required, the dye pumps can be controlled manually from the control console. The system can be programmed to express the measured colour values in terms of different colour measurement systems. At present, colour values can be given in accordance with the following measurement systems : - purity - dominant wave length - whiteness - luminance - L, a, b - .1 L, .1a, .1 b - .1E
- X, Y, Z
- Rx, Ry, Rz OPERATION
or
THE 'COlOURKllPER'
Measurement The COLOUR KEEPER system's measurements are continuous and occur from the web. The colour values are expressed in terms of the CIE standard proportional to the X, Y, Z signals. These signals are transmitted to the control console via the power supply unit where they are ampli fied. The micro-computer in the electronic cabinet transforms these signals into the correct form required by the output medium (i.e. display, strip chart recorder, etc.). Measurement occurs once a second. The measured values are stored in the micro-computer memory, so that they can be averaged and reported at one minute intervals. The electronic cabinet and the Reports The General Unit micro-computer is located in separate electronics cabinet. The micro com-
Different alarms can be given for - colour values - dosage pumps - system condition The operator is notified of these alarms at the keyboard by special alarm lights and/ or by the printer. Dosage Controls (Figure 3) The COLOURKEEPER system has an optional control package for controlling up to three colour or dye dosing pumps simultaneously. The basic model for the dosage control is a 3x3 matrix. This matrix indicates the colour or dye components required for the measured colour values. The controls are the computer programs P, PI and PlO. These programs are selected when the system is operational.
Col our and Brightn e ss Mea surement a nd Contr ol Sys t em
243
The models and controllers are synchronized while the system is operating. This is done via the keyboard and display.
brightness. These figures substantially improved when the COLOUR KEEPER system was introduced.
Calibration The COLOUR KEEPER system contains an automatic calibration micro-computer program. The calibration is done automatically at specific time intervals without the aid of an operator.
Rejections before the COLOUR KEEPER system was in use ( figure 4 )
This operation through the movement of the measuring head and the tests made to determine the system's condition prevents the accumulation of dirt.
Rejections after the COLOURKEEPER system was in use
Movement Control The measuring head moves automatically to the side during alarms and web breaKs.
SERVICING AND MAINTENANCE Of THE 'COlOURKEEPER' SYSTEM The measuring head's cooling and cleaning system is one of the essential ingredients in its successful operation because its optics, lamps, calibration and backing all require regular maintenance. The measuring head, power supply unit, keyboard/display unit, and the electronic cabinet can be freely placed according to the customer's requirements. The equipment is mounted so as to facilitate weekly servicing. Special tools are not required. A diagnostic program tests the micro-computer's input/output and memory cards.
OPERATION OF THE COLOURKEEPER SYSTEM Presently, COLOURKEEPER is in use in newsprint and fine paper mills as well as in a tissue mill. The paper grades are shaded or highly dyed, a~d the basis weights range from 33 to 150 g/m for ~ewsprint and fine paper and from 15 to 24 g/ m for tissue. COLOURKEEPER's first reference installation has been in operation for over three years at PM2 of Ahlstroem's Varkaus Paper Industry. PM2's annual output is approximately 60.000 tons. Actual test-run trials at PM2 show that COLOURKEEPER reduces rejects caused by discoloration or offshading by more than 2U%. Rejected production caused by discoloration or off-shading was computed on an annual basis. This was calculated from 1) the rejected roll specification and 2) rejections before the winder on the basis of run reports. About 50 times, during the period under study ( 8 months), production was rejected because of critical changes in paper colour and
Rejected rolls Rejected reels
Rejected rolls Rejected reels
660 tons 340 tons
520 tons 270 tons
This represents a more than 20% decrease in production rejection and therefore represents a substatial increase in production efficiency, which of course can be expressed in terms of money. Moreover, additional savings are accomplished by reducing the time required for grade changes. The time per grade change which earlier used to be in the order of one shift (i.e. 5 to 8 hours ) is now, with the use of COLOURKEEPER, of the order of 1 or a maximum of 2 hours. The above data refers to PM2 of Ahlstroem's Varkaus Paper Industry. Such data may be different in another mill's circumstances.
IMPROVED QUALITY CONTROL During manually controlled long runs, shade and brightness easily change. (The broken line in Figure 5.) During automatically controlled COLOURKEEPER runs, fluctuations in colour and brightness are substantially reduced. ( The solid line in Figure 5. ) This is a result of the more frequent or even fully continuous quality control.
THE ADVANTAGES Of THE NEW ON-LINE COLOUR AND BRIGHTNESS MEASUREMENT AND COLOUR CONTROL SYSTEM 1. Reliable data on paper colour is continuously obtained. This means that the time used to control any irregularities is considerably shortened. 2. During a regular production run, light patches often occur in the pulp. The COLOURKEEPER system can perform changes in the pulp which compensate for these colour irregularities without producing rejected rolls. 3. By optimizing on-line control of the entire colouring process, changes from one colour or shade to another can be performed easily and quickl y. 4. The COL OUR KEEPER system eliminates the need for pre-prepared colour mixtures. With
244
M. Leht ovii t a
its optional colour control package, the COLOUR KEEPER system can automatically mix the required colour by adjusting the dosage. CONCLUSIONS The monitoring of paper quality in the paper mill is becoming increasi ngly important as the capacity and quality requirements of both the paper mills and the printing houses continue to rise.
The continuous on-line colour and brightness measurement and control system which is described in this paper is noteworthy for the production of even colour, the reduction of colour broke, and the shortening of the time required for grade changes. The reliability of the equipment used has been excellent because of the distributed arrangement of the system. The measurement and reporting of colour values have also been of the same high standard of reliability.
COLOURKEEPER ON-LINE COLOUR MEASUREMENT AND CONTROL SYSTEM
\
ELEKTRONIC CABINET AND DISPLAY / KEYBOARD UNIT • SEVERAL DYE COMPONENTS CAN BE CONTROLLED SIMULTANEOUSLY
• SELF-STANDARDIZING AHO SELF-CALIBRATING • NOt+-SENSITIVE TO HEAT, MOISTUR~ DUST AND FLUTTER OF PAPER WEB F ig.
1
• COMPACT UNIT WITH A BUILD -IN MICROCOMPUTER • SEPARATE DISPLAY / KEYBOARD UNIT
24 5
Colour and Brightness Measurement and Control System
SIGNAL TO POWER SUPPLY UNIT
WEB
Fig.
2
COMPUTER - CALCULATES X, Y AND Z VALUES - P, PI AND T CONTROLLERS - CALCULATES - PURITY - WAVE LENGTH - BRIGHTNESS - L••. b
r-------------
r----------- r -------- - -
THICK STOCK
HEAD BOX WIRE
WHITE WATER TANK
A SCHEMATIC DIAGRAM OF COLOUR CONTROL LOOP
Fig. 3
DRYERS
POWER SUPPLY UNIT
OPTICAL
f7 MEASURING I HEAD
WASTE PULPER
246
M. Lehtovii ta
COLOURKEEPER ECONOMIC EFFECTIVENESS OF COLOURKEEPER Production (MFIM) 2
--------20 % ----
---- --20-i ----
Rejected reels Before After COLOURKEEPER
Rejected rolls Before After COLOUR KEEPER
"REJECTS BEFORE INSTALLATION OF COLOUR KEEPER Rejected rolls 660 tons Rejected reels 340 tons •
REJECTS AFTER INSTALLATION OF COLOURKEEPER Rejected rolls 520 tons Rejected reels 270 tons
THE QUANTITY OF REJECTS DECREASED BY 20 % Fig. 4 COLOUR VALUE
SET POINT I \
I \
I \
I
\
V
\
\
I
\
\
I \
I
I V
TIME
A SCHEMATIC REPRESENT A TION OF THE DIFFERENCE BETWEEN THE MANUALLY CONTROLLED RUNS (BROKEN LINE) AND THE AUTOMA TlCALL Y CONTROLLED COLOURKEEPER RUNS (SOLID LINE) IN THE REGULATION OF COLOUR. F" 5
19,
11·. \(
I II"'( l rlll!l"rn,tli"11 ,tlH I . \ ~II! II. 1 r. ll i !1]1
ill lilt' P ,qlt' l . R uhI H.." r ( IH!II"'l l
il" . .\1 11\\ l'1 I).
1' 1.1,1
it,
Ik l-..:illll l
,111t1
III
1'\ I'Ll{ \\\11
d\ IlI tT I .... ll1IJlI
I ~I ,,:)
NEW ON-LINE COLOUR AND BRIGHTNESS MEASUREMENT AND CONTROL SYSTEM M. Lehtoviita
Abstract. In recent years, the on-line measurement and control of colour and brightness has stimulated great interest in the paper industry. The monitoring and control of paper quality in the paper mill is becoming increasingly important as the capacity and quality requirements of both the paper mills and the printing houses continue to rise. The continuous on-line measurement and control system described in this paper is noteworthy for the production of even colour, the reduction of colour broke, and tne snortening of the time required for grade and colour changes.
BACKGROUND
There have been some difficulties associated with continuous measurement on a paper machine in comparison to measurement in the laboratory. The conditions in a paper machine are different from those in the laboratory in regard to temperature, vibration, and dirt, for example. In the paper mill environment electrical interference may cause difficulties in the handling of measurement signals. Also, a colour meter installed on-line cannot be in direct contact with the web. The on-line measurements are therefore taken from a single fluttering sheet of web at a distance of about 7 mm.
The wood-based industries, and especially the paper industry, dominate Finnish economic life. In 19t1I, about 4U ~O of all Finnish exports derived from this sector. As a result, large sums of money have been spent, and continue to be spent, to further the development of these industries. Of special note are the Finnish developments in the area of computer applications. In Ahlstroem's Varkaus Paper Industry, the first computer based system for monitoring and control of production was "on-line" about 1969. Later, laboratory and quality control became computer based. In its first applications, quality control included only the laboratory tests of some of the end product values. But today quality control involves a whole range of operations including the control of raw material quality and a multitude of process controls.
The possibilities for calibration in on-line measurement are limited compared to laboratory conditions. The fact that the measuring head generally is installed between the calender and the Pope limits the size of the measuring head. While this location is generally a convenient place, other measuring equipment is often already installed there.
THE 'COLOURKEEPER' COLOUR HEASURING AND CONTROL SYSTEH
At first only the measurement and control of moisture and basis weight were computer based. But today, the new micro-computer technology has opened many more possibilities to develop quality control systems for the paper industry. One such application is the continuous measurement and control of colour and brightness.
( Figure 1) The COLOURKEEPER system consists of four basic parts : - the measuring head and its mounting frame - the power supply unit - the electronic cabinet - the display unit and the keyboard
COlOUR MEASUREMENT IN GENERAL The measuring head includes lamps, optics, a filter / photo cell, and an automatic reference plate unit.
The paper industr y 's interest in continuous colour measurement systems has increased due to the demand for higher paper quality, for better optical characteristics, and for less broke. The technological advances in colour meters and their associated equipment nave also stimulated the industry's interest.
The Hunter D43 optical measuring head is used as the measuring sensor. The measuring head employs a light source comprised of two matched quartz iodine lamps. The energy from each lamp is collected and focused through
!'::'A- : ..
241
M. Lehtoviit a
24 2
separate apertures onto the specimen surface. The two opposing beams of light strike the specimen at 37° to a line perpendicular to the specimen surface. Light diffusely reflected from the specimen is collected and transformed into electrical signals corresponding to Xa, Xb, Y and Z values. The measuring head is protected from accumulating airborne dust particles by a flow of filtered air which also serves to provide the necessary cooling. The power supply unit contains amplifiers, solid state power supplies, and the output to related equipment. The regulated lamp power is also located in the power supply unit. The electronic cabinet contains micro-computer and electronics. The display unit contains a plasma-display.
INSTALLATION
or
THE 'COLOURKEEPER'
ON A PAPER MACHINE
(Figure 2) The measuring head and its mounting frame are installed on a paper machine in the manner shown in Figure 2. Riding on the mounting frame are two carriages positioned both above and below the web. The measuring head is fixed to the upper carriage while the standard plate is secured to the lower carriage. Both carriages move simultaneously and are controlled by a computer programme governing pneumatic cylinders. The measurement is taken from one fixed position on the paper web. This position is about one meter from the edge of the web. The measuring head can be moved off the paper web in case of web breaks, for servicing, and for calibration.
puter consists of an Intel b085 based CPUcard. In addition, there is a 20 Kb program memory and an 8 Kb data memory. All cards in the micro-computer are standard and can be easily changed. The extent of the electronics varies according to the number of functions and field interfaces required. To operate, the system must be energized, and a minimal amount of data is fed into the system by the operator. The following is entered from the control console : - colour value set point, variation values - pumps to be used - dye concentrations to be used - backing data - frequency of reports - grade data - time - mathematical models - controller's calibration values Part of this data is already included in a previously entered code number or grade number. However, this code number can be changed in certain circumstances. For grade changes, the code number is the least that must be given. If required, the dye pumps can be controlled manually from the control console. The system can be programmed to express the measured colour values in terms of different colour measurement systems. At present, colour values can be given in accordance with the following measurement systems : - purity - dominant wave length - whiteness - luminance - L, a, b - .1 L, .1a, .1 b - .1E
- X, Y, Z
- Rx, Ry, Rz OPERATION
or
THE 'COlOURKllPER'
Measurement The COLOUR KEEPER system's measurements are continuous and occur from the web. The colour values are expressed in terms of the CIE standard proportional to the X, Y, Z signals. These signals are transmitted to the control console via the power supply unit where they are ampli fied. The micro-computer in the electronic cabinet transforms these signals into the correct form required by the output medium (i.e. display, strip chart recorder, etc.). Measurement occurs once a second. The measured values are stored in the micro-computer memory, so that they can be averaged and reported at one minute intervals. The electronic cabinet and the Reports The General Unit micro-computer is located in separate electronics cabinet. The micro com-
Different alarms can be given for - colour values - dosage pumps - system condition The operator is notified of these alarms at the keyboard by special alarm lights and/ or by the printer. Dosage Controls (Figure 3) The COLOURKEEPER system has an optional control package for controlling up to three colour or dye dosing pumps simultaneously. The basic model for the dosage control is a 3x3 matrix. This matrix indicates the colour or dye components required for the measured colour values. The controls are the computer programs P, PI and PlO. These programs are selected when the system is operational.
Col our and Brightn e ss Mea surement a nd Contr ol Sys t em
243
The models and controllers are synchronized while the system is operating. This is done via the keyboard and display.
brightness. These figures substantially improved when the COLOUR KEEPER system was introduced.
Calibration The COLOUR KEEPER system contains an automatic calibration micro-computer program. The calibration is done automatically at specific time intervals without the aid of an operator.
Rejections before the COLOUR KEEPER system was in use ( figure 4 )
This operation through the movement of the measuring head and the tests made to determine the system's condition prevents the accumulation of dirt.
Rejections after the COLOURKEEPER system was in use
Movement Control The measuring head moves automatically to the side during alarms and web breaKs.
SERVICING AND MAINTENANCE Of THE 'COlOURKEEPER' SYSTEM The measuring head's cooling and cleaning system is one of the essential ingredients in its successful operation because its optics, lamps, calibration and backing all require regular maintenance. The measuring head, power supply unit, keyboard/display unit, and the electronic cabinet can be freely placed according to the customer's requirements. The equipment is mounted so as to facilitate weekly servicing. Special tools are not required. A diagnostic program tests the micro-computer's input/output and memory cards.
OPERATION OF THE COLOURKEEPER SYSTEM Presently, COLOURKEEPER is in use in newsprint and fine paper mills as well as in a tissue mill. The paper grades are shaded or highly dyed, a~d the basis weights range from 33 to 150 g/m for ~ewsprint and fine paper and from 15 to 24 g/ m for tissue. COLOURKEEPER's first reference installation has been in operation for over three years at PM2 of Ahlstroem's Varkaus Paper Industry. PM2's annual output is approximately 60.000 tons. Actual test-run trials at PM2 show that COLOURKEEPER reduces rejects caused by discoloration or offshading by more than 2U%. Rejected production caused by discoloration or off-shading was computed on an annual basis. This was calculated from 1) the rejected roll specification and 2) rejections before the winder on the basis of run reports. About 50 times, during the period under study ( 8 months), production was rejected because of critical changes in paper colour and
Rejected rolls Rejected reels
Rejected rolls Rejected reels
660 tons 340 tons
520 tons 270 tons
This represents a more than 20% decrease in production rejection and therefore represents a substatial increase in production efficiency, which of course can be expressed in terms of money. Moreover, additional savings are accomplished by reducing the time required for grade changes. The time per grade change which earlier used to be in the order of one shift (i.e. 5 to 8 hours ) is now, with the use of COLOURKEEPER, of the order of 1 or a maximum of 2 hours. The above data refers to PM2 of Ahlstroem's Varkaus Paper Industry. Such data may be different in another mill's circumstances.
IMPROVED QUALITY CONTROL During manually controlled long runs, shade and brightness easily change. (The broken line in Figure 5.) During automatically controlled COLOURKEEPER runs, fluctuations in colour and brightness are substantially reduced. ( The solid line in Figure 5. ) This is a result of the more frequent or even fully continuous quality control.
THE ADVANTAGES Of THE NEW ON-LINE COLOUR AND BRIGHTNESS MEASUREMENT AND COLOUR CONTROL SYSTEM 1. Reliable data on paper colour is continuously obtained. This means that the time used to control any irregularities is considerably shortened. 2. During a regular production run, light patches often occur in the pulp. The COLOURKEEPER system can perform changes in the pulp which compensate for these colour irregularities without producing rejected rolls. 3. By optimizing on-line control of the entire colouring process, changes from one colour or shade to another can be performed easily and quickl y. 4. The COL OUR KEEPER system eliminates the need for pre-prepared colour mixtures. With
244
M. Leht ovii t a
its optional colour control package, the COLOUR KEEPER system can automatically mix the required colour by adjusting the dosage. CONCLUSIONS The monitoring of paper quality in the paper mill is becoming increasi ngly important as the capacity and quality requirements of both the paper mills and the printing houses continue to rise.
The continuous on-line colour and brightness measurement and control system which is described in this paper is noteworthy for the production of even colour, the reduction of colour broke, and the shortening of the time required for grade changes. The reliability of the equipment used has been excellent because of the distributed arrangement of the system. The measurement and reporting of colour values have also been of the same high standard of reliability.
COLOURKEEPER ON-LINE COLOUR MEASUREMENT AND CONTROL SYSTEM
\
ELEKTRONIC CABINET AND DISPLAY / KEYBOARD UNIT • SEVERAL DYE COMPONENTS CAN BE CONTROLLED SIMULTANEOUSLY
• SELF-STANDARDIZING AHO SELF-CALIBRATING • NOt+-SENSITIVE TO HEAT, MOISTUR~ DUST AND FLUTTER OF PAPER WEB F ig.
1
• COMPACT UNIT WITH A BUILD -IN MICROCOMPUTER • SEPARATE DISPLAY / KEYBOARD UNIT
24 5
Colour and Brightness Measurement and Control System
SIGNAL TO POWER SUPPLY UNIT
WEB
Fig.
2
COMPUTER - CALCULATES X, Y AND Z VALUES - P, PI AND T CONTROLLERS - CALCULATES - PURITY - WAVE LENGTH - BRIGHTNESS - L••. b
r-------------
r----------- r -------- - -
THICK STOCK
HEAD BOX WIRE
WHITE WATER TANK
A SCHEMATIC DIAGRAM OF COLOUR CONTROL LOOP
Fig. 3
DRYERS
POWER SUPPLY UNIT
OPTICAL
f7 MEASURING I HEAD
WASTE PULPER
246
M. Lehtovii ta
COLOURKEEPER ECONOMIC EFFECTIVENESS OF COLOURKEEPER Production (MFIM) 2
--------20 % ----
---- --20-i ----
Rejected reels Before After COLOURKEEPER
Rejected rolls Before After COLOUR KEEPER
"REJECTS BEFORE INSTALLATION OF COLOUR KEEPER Rejected rolls 660 tons Rejected reels 340 tons •
REJECTS AFTER INSTALLATION OF COLOURKEEPER Rejected rolls 520 tons Rejected reels 270 tons
THE QUANTITY OF REJECTS DECREASED BY 20 % Fig. 4 COLOUR VALUE
SET POINT I \
I \
I \
I
\
V
\
\
I
\
\
I \
I
I V
TIME
A SCHEMATIC REPRESENT A TION OF THE DIFFERENCE BETWEEN THE MANUALLY CONTROLLED RUNS (BROKEN LINE) AND THE AUTOMA TlCALL Y CONTROLLED COLOURKEEPER RUNS (SOLID LINE) IN THE REGULATION OF COLOUR. F" 5
19,