Note: Descriptions are shown in the official language in which they were submitted.
27~
,
AUTOMATIC SETUP APPARATUS FOR AN
ELE~TROPHOTOGRAPHIC PRINTING MACHINE
This invention relates to electrophotographic printing machines
and, more particularly, to a completely automated apparatus for establishing
basic xerographic parameters at values previously determined to produce
optimum output copy quality.
In electrophotographic devices, such as a xerographic copier or
printer, a photoconductive surface is charged to a substantially uniform
potential. The charged portion of the photoconductive surface is exposed to a
light image of an original document being reproduced3 forming an electrostatic
latent image at the photoconductive surface corresponding to the informa-
tional areas contained within the original document. The electrostatic latent
image is subsequently developed by bringing a developer mixture into contact
therewith. The developed image is subsequently transferred to an output copy
sheet. The powder image on the output sheet is then heated to permanently
affix it to the sheet in the image configuration.
For any given population of electrophotographic printing machines,
a primary control objective is to maintain uniform optimum copy quality from
machine to machine. This goal has proven difficult to achieve since each
machine experiences its own peculiar changes during extended operation.
These changes include aging of the developer mixture, changes in environment,
variations in the dark development potential, and residual voltage of the
photoconductor or photoreceptor surface, a thinning of the photoreceptor
surface due to abrasion, photoreceptor fatigue, exposure lamp illumination
variations, and changes in the toner material concentration due to
consumption. These variations, singly or cumulatively, have adverse affects
on output copy quality that must be identified and compensated for on a
continuous basis.
Various control schemes are known to compensate for the variable
factors listed above. These schemes involve adjustment of basic control
parameters, viz. adjusting the current of the device used to deposit the charge
on the photoconductive surface, adjusting the bias applied to the development
unit, varying the concentration of the toner mixture and changing the exposure
level. All of these adjustments are interrelated and their proper selection by amachine operator during operation, or a technician during initial setup, have
proven difficult and expensive to achieve, as well as time consuming.
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Generally also, some kind of test density target, either a special document, or
an articulated device is necessary to calibrate exposure levels.
It would be desirable, therefore, to provide a control apparatus
that adjusts for these various functions in a manner that is automated so as to
reduce the potential for human error. It would be desirable to perform these
adjustments within a relatively short period of time, using an apparatus that iswholly self-contained, e. gO does not require the use of portable current and
voltage measuring devices.
In accordance with the present invention, there is provided an
apparatus for automatically adjusting basic xerographic parameters in a
periodic initialization mode so as to establish predetermined copy quality and
density. This apparatus includes optical means for forming at least four
varying density patches on a precharged photoconductive surface, means for
sensing the charged levels at three of said density patches, control means
having stored therein a set of interrelated electrical values which define a
predetermined photo-induced discharge curve (PIDC), said control means
adapted to evaluate said sensed charge levels and determine whether they
establish convergence with the desired PIDC and, through an iterative process,
to vary charge current and exposure levels, until such convergence is realized
and means responsive to the density of toner particles deposited on a fourth
density patch for controlling the concentration of toner particles in the
developer mixture.
More particularly, the invention relates to apparatus for optimizing
the operation of an electrophotographic printing machine having a corona
device for applying a charge to the machine photoreceptor, a scan-illumination
optical system for ;lluminating a docurnent to be copied on a platen surface
and for projecting an image of the document alonK an optical path onto the
photoreceptor to form a latent image thereof, a developer unit for applying
toner to the belt surface, said apparatus further comprising, in combination:
a digital controller,
memory means within said controller, having stored therein a
digital representation of the photo-induced discharge curve (PIDC) for the
machine photoreceptor,
optical test patch generation means comprising part of said scan-
illumination system, said patch generation means adapted to form at least a
dark development VDDp patch, a second, full illumination VgG patch and a
third intermediate development patch on said photoreceptor,
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a voltmeter for sensing photoreceptor voltage at said
test patch areas and for sending representative signals to
said memory means,
first logic means within said controller for
analyzing the voltmeter input signals representing the
values VDDp and VBG levels, comparing the difference
(constant contrast voltage Vc), between these signals and
a preset optimum value of Vc stored ~ithin the memory
means and selectively regulating the corona device and the
developer unit in an iterative process until convergence
is obtained between said difference and said preset value,
said logic means further adapted to analyze the
voltmeter input signals representing said intermediate
development patch, comparing said signal with a preset
optimum value stored within the memory means and
selectively regulating the illumination output level of
said scan-illumination optical system in an iterative
process until convergence is obtained between said
measured and stored values.
An~ther aspect of this invention is as follows:
The process of automatically adjusting the basic
xerographic parameters of an electrophotographic printing
machine evaluating charging circuit Ic, developer bias
VBIAS and system exposure Eol comprising the steps of:
a) driving the machine document scanning optics in
a test patch generation mode to lay down a plurality of
teæt patches of different densities on the machine
photoreceptor, including a first test patch representing
dark decay potential VDDp, a second patch representing
background voltage level VBG and a third patch
representing an intermediate voltage level V0 30,
b) measuring the voltage levels at said test
patches and generating signals indicative thereof,
c) analyzing said voltage level signals and
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comparing preset values representative of values lying
along the PIDC curve of the particular photoreceptor,
d) adjusting the machine parameters Ic, VBIASl and
Eo until these comparison values find convergence with
these points on the PIDC curve established for the machine
photoreceptorO
Other aspects of the present invention will become
apparent as the following description proceeds and upon
reference to the drawings in which:
Figure l is a side schematic view of an
electrophotographic printing machine incorporating the
features of the present invention;
Figure 2 shows PIDC plot of Exposure vs.
Photoreceptor Potential;
Figure 3 is a block diagram of the system controller;
Figure 4a, 4b is a functional flow diagram of the
patch generation portion of the automatic setup procedure;
Figure 5 is a side schematic view of the scan
carriage at separate density generating positions;
Figure 6 is a time vs. voltage plot of the test patch
generation sequence;
Figure 7 is a top view of a portion of the
photoreceptor belt having test patches formed thereon;
Figure 8 is a functional flow diagram of the 0.3D
density patch generation;
Figure 9 is a functional -Elow diagram showing the
exposure convergence sequence;
Figure 10 is a time vs. voltage plot of the 0.7
density test patch generation;
Figure 11 is a top view of a portion of the
photoreceptor but having 0.7 density patch formed thereon.
For a general understanding of the features of the
present invention, reference is made to the drawings. In
the drawings, like reference numerals have been used
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throughout to designate identical elements. Figure 1
schematically depicts the various components of an
illustrative electrophotographic printing machine
incorporating the control system of the present invention
therein. It will become apparent from the following
discussion that this control system is equally well suited
for use in a wid~ variety of electrophotographic printing
machines and is not necessarily limited in its application
to the particular embodiment sho~n herein.
Inasmuch as the art of electrophotographic printing
is well known, the various processing stations employed in
the Figure 1 printing machine will be shown hereinafter
schematically and their operation described briefly with
reference thereto.
Turning now to Figure l, the electrophotographic
p-rinting machine uses a photoreceptor belt 10 having a
photoconductive surface 12 formed on a conductive
substrate. Preferably, belt 12 has characteristics
disclosed in U. S. Patent 4,265,990. Belt 10 moves in the
indicated direction, advancing sequentially through the
various xerographic process stations. The belt is
entrained about drive roller 16 and tension rollers 18,
20. Roller 16 is driven by conventional motor means, not
shown.
With continued reference to Figure l, a portion of
belt 10 passes through charging station A where a corona
generating device, indicated generally by the reference
numeral 22, charges photoconductive surface 12 to a
relatively high, substantially uniform, negative
potential. Device 22 comprises a charging electrode 2
and a conductive shield 26. A high voltage supply 30
controlled by a portion of controller 31, is connected to
shield 26. A change in the output of power supply 30
causes a change in charging current, IC, and consequently,
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a change in the charge potential applied to surface 12.
As belt 10 continues to advance, the charged portion
of surface 1~ moves into exposure station B. An original
document 32 is positioned, either manually, or by a
document feeder mechanism (not shown) on the ~urface of a
transparent platen 34. optics assembly 36 contains the
optical components which incrementally scan-illuminate the
document and project a reflected image onto surface 12 of
belt 10. Shown schematically, these optical components
romprise an illumination scan assembly 40, comprising
illumination lamp 42, associated reflector 43 and full
rate scan mirror 44, all three
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components mounted on a scan carriage 45. The carriage ends are adapted to
ride along guide rails (not shown) so as to travel along a path parallel to and
beneath, the platen. Lamp 42 illuminates an incremental line portion of
document 32. The reflected image is reflected by scan mirror 44 to corner
mirror assembly 46 on a second scan carriage 46A moving at 1/2 the rate of
mirror 4~. The document image is projected through lens 47 and reflected by
a second corner mirror 48 and belt mirror 50, both moving at a predetermined
relationship so as to precess the projected image, while maintaining the
required rear conjugate onto surface 12 to form thereon an electrostatic
latent image corresponding to the informational areas contained within
original document 32. Adjustable illumination power supply 51, controlled by a
portion of controller 31, supplies power -to lamp 42. The optics assembly 36,
besides operating in a document scanning mode, is also used in the automatic
setup mode of the present invention, to generate and project four alternating
density patches onto the centerline of the belt 10 fGr purposes to be described
more fully below. Positioned between exposure station B and development
station C, and adjacent to surface 12, is electrostatic voltmeter 52.
Voltmeter 52 preferably is capable of measuring either positive or negative
potentials and utilizes ac circuitry requiring no field calibration. Voltmeter
52, in the automatic setup mode, generates a first signal proportional to the
dark decay potential Vo on photoconductive surface 12. The dark develop-
ment potential is the charge at surface 12 after charging and exposure
reflected from an opaque object. The voltmeter also generates a second signal
proportional to background potential Vg, on the photoreceptor surface. The
background potential is the charge on the photoreceptor after exposure with
light reflected Erom a white object. Both of the voltmeter output signals are
sent to controller 31 through suitable conversion circuitry. Controller 31
operates upon these values, comparing them to values related to a desired
output quantity in the controller memory. Adjustments are made by the
controller to the charging and development bias voltage and to the illumina-
tion power supply in an iterative process described in further detail below:
Referring again to Figure I, discrete patch generator 53 is a
calibrated LED light source which is energized in one of two modes of
operation. In a first mode, operable during the automatic setup mode, a
dedicated digital input provides for LED energization at a high fixed level.
This mode is used primarily for erasing test patch areas generated during the
setup procedures. In a second mode of operation, following the initial system
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setup, an analog reference input to the generator 53
provides for energization of the LEDs 50 as to generate a
variable light intensity for use in toner control in
several contrast modes as described in greater detail
below.
At development station C, a magnetic krush
development system, indicated generally by the reference
numeral 54, advances an insulating development material
into contact with the electrostatic latent image.
Preferably, magnetic brush development system 54 includes
a developer roller 56 within a housing 58. Roller 56
transports a brush of developer material comprising
magnetic carrier granules and toner particles into contact
with belt 10. Roller 56 is positioned so that the brush
of developer material deforms belt 10 in an arc with the
belt conforming, at least partially, to the configuration
of the developer material. The thickness of the layer of
developer material adhering to developer roller 56 is
adjustable. Roller 56 is biased by voltage source 57 to a
voltage level VD.
The electrostatic latent image attracts the toner
particles from the carrier granules forming a toner powder
image on photoconductive surface 12. The detailed
structure of the magnetic brush development system is more
fully disclosed in U. S. Patent 4,397,264.
As successive latent images are developed, toner
particles are depleted from the developer material. A
toner particle dispenser, indicated generally by the
reference numeral 60 provides additional toner particles
to housing 58 for subsequent use by developer roller 56.
Toner dispenser 60 includes a container for storing a
supply of toner particles therein and means (not shown)
for introducing the particlss into developer housing 58.
A motor 62, when energized, initiates the operation of
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dispenser 60.
Infrared densitometer 64, positionPd adjacent belt 10
and located between developer station C and transfer
station D, directs infrared light onto surface 12 upon
appropriate signals from the controller 31. The ratio of
reflected light on a developed area to that of a bare area
is an indication of toner patch developability. The
densitometer generates output signals and sends them to
controller 31 through appropriate conversion circuitry.
The controller operates upon these signals and sends
appropriate output signals to motor 62 to control
dispensing of toner particles. Densitometer 64 is also
used to periodically measure the light rays reflected from
the bare photoconductive surface (i. e. without developed
toner particles) to provide a reference level for
calculation of the signal ratios.
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Continuing with the system description, an output copy sheet 66
taken from a supply tray 67, is moved into contact with the toner powder
image at transfer station D. The support material is conveyed to station D by
a pair of feed rollers 68, 70. Transfer station D includes a corona generating
device 71 which sprays ions onto the backside of sheet 66, thereby attracting
the toner powder image from surface 12 to sheet 66. After transfer, the sheet
advances to fusing sta-tion E where a fusing roller assembiy 72 affixes the
transferred powder image. After fusing, sheet 66 advances to an output tray
(not shown) for subsequent removal by the operator.
After the sheet of support material is separated from belt 10, the
residual toner particles and the toner particles of developed test patch areas
are removed at cleaning station F.
Subsequent to cleaning~ a discharge lamp, not shown, floods surface
12 with light to dissipate any residual charge remaining thereon prior to the
charging thereof for the next imaging cycle.
It is believed that the foregoing description is sufficient for
purposes of the present application to illustrate the general operation of an
electrophotographic printing machine incorporating the features of the present
invention therein.
2~ These features may be briefly summarized as:
1. Control of pre-development photoreceptor potentials using
voltmeter 52 and associated controller circuitry;
2. Generation of multiple exposure levels (test patches) using
the system optics assernbly 36; and
3. Control of developed image density by using densitometer 64
to measure the reflectance of developed toner patches.
According to further aspects of the invention, only two of the
sensors, the voltmeter and the densitometer, need to maintain an absolute
calibration. All major xerographic parameters are automatically established
30 during the automatic setup mode and are automatically maintained thereafter.
The setup procedure is reproducible over time within a single machine and
from machine to machine across a population of machines.
Automatic Setup Mode
Upon initial installation of a particular electrophotographic
35 printing machine and periodically (daily) thereafter, the basic machine
parameters are automatically checked and adjusted. Each machine is
associated with the same development potentials (Vl - VD) by adjustment of
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the shape of the photo-induced discharge curve (PIDC)
which has previously been determined to ensure uniform
output copy quality across the machine population. A PIDC
is a fundamental characteristic of a photoreceptor that
has been charged to a specific dark potential VO in
combination with the reflective density of the input
document and the document illumination intensity. But any
given population of photoreceptors will have a
distribution of shapes. Figure 2 shows a typical plot for
a machine with the range of values indicated. Digital
values representing the PIDC slope are contained within
controller 31 memory of each machine. The setup mode and
associated apparatus is designed to measure the basic
parameters of the particular machine and plot the PIDC,
based on these measured values. Insofar as the actual
PIDC shape varies from the standard, adjustments are made
to the basic parameters of charge voltage Ic, developer
bias VBIAS and system exposure Eo in an iterative process,
until convergence of the measured, with the preset, values
is realized. These basic control circuit subsystems which
accomplish these operations are shown in Figure 3.
Referring to this Figure, controller 31 consists of
Input/Output Board 80, and master control board 82,
Input/Output processor 86 and a serial bus controller 88.
Input signals from the densitometer 64, voltmeter 52 and
patch generator 53 are converted by 1/0 board 80; sent to
1/0 processor 86 and then to processor 84. Output signals
are sent to adjust the corona generator, system
illumination, toner dispenser and development bias via
processor 86. Operation of the optical scanning system is
controlled by processor 84 via controller 88.
The master control processor is an Intel (Trade Mark)
Model 8085 which can be programmed to perform the
described iterative functions, using the algorithms set
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forth in the Appendix. Incorporation of these algorithms
into a larger and central unit is a procedure well
understood by those skilled in the art.
The automatic setup mode is initiated by applying
initial power application to the machine. The sequence of
operations occurring thereafter is shown with reference to
Figure 4a, 4b.
Figure 4a, 4b is a flow chart sequence of these
operations. Figure 5 is a side view schematic drawing of
the scan carriage at different density patch generating
positions. Figure 6 is a time vs. voltage plot of the
test patch generation sequence, and Figure 7 is a top view
of belt 10 showing the imaged patch zones. Figure 9 is a
flow chart of the test patch generator and machine
functions. Referring to Figures 4a, 5, and 6, once
machine power is turned on, the photoreceptor moves
through a first cycle of operation at the
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system process speed. Scan carriage 45 moves to the home park position.
Carriage 45, in this position is shown to the left of the platen in Figure 5. The
components are shown dotted. Scan lamp 42 is energized at the normal lamp
power level used during the preceding operational interval. An opaque
occluder is positioned in the optical path at a point above the belt 10 surface,thus preventing light from falling on the surface in an area corresponding to
the occluder. Thus a first test patch 100 shown formed on the belt centerline
in Figure 7 is therefore at the dark decay charging level VDDp. Carriage 45 is
then moved to the right, scanning at a constant velocity, until it reaches park
position 1 past the end of scan position (shown in solid line in Figure 5). At
this position, a 0.3 density strip 90 centrally overlies the scan carriage. At
this point, lamp 42 output is doubled so as to form a second patch area 102
conforming in size to strip 90 representing a 100% transmission, completely
discharged strip at background voltage level, VgG.
With carriage 45 still in the solid line position shown in Figure 5,
the lamp illumination input is halved. The exposed patch area 104 on belt 10
forms a 0.3 density patch 104 on the photoreceptor. Carriage 45 is then
returned to the home position and a second VDDp patch 106 is formed on the
center line of belt 10.
Further operation of the carriage is dependent upon whether PIDC
convergence is present as determined by comparisons of voltmeter-generated
signals processed by the microprocessor 84 and compared to values stored in
the microprocessor memory.
Electrostatic voltmeter 52, shown in Figure 1, is used to directly
sense photoreceptor voltage at the test patch areas 100, 102, 104, 106. The
voltmeter is positioned approximately 3 mm from the belt surface.
Figure 4b shows the functional flow diagram for the voltmeter
readings and the related microprocessor control operation. Referring to this
figure, and to Figure 6, the voltmeter measures each of test patch charge
30 levels on successive belt cycles. Signals representing the voltage at patch 100
(VDDp), patch 102 (VgG) and patch 104 (Vo.3D) are sent to the control
processor 84 through the associated l/O circuitry and temporarily stored
therein. The difference between VDDp and VgG is computed by logic means
within the controller and a signal, representing this value and designated
35 constant contrast voltage (Vc) is generated. This signal is compared to a
preset VCSET (VS~ If VC ~ Vs, (no convergence), a signal is generated within
the processor and sent to change the bias (VGRID) on the charge electrode 24
-10-
(Figure 1) thereby changing the value of charge current Ic and the value of
VDDp. Signals are also sent to patch generator 53 to erase the previously
generated patch areas. Scan carriage 45 then repeats the sequence described
with respect to Figures 4a and 5, beginning at the home park position and
5 continuing to park position 2. The newly formed patches are again read by the
voltmeter and compared by processor 84 (Fig. 4b). This process is an iterative
one governed by a control algorithm set forth in the Appendix; the process is
continued until the measured value of Vc conforms to Vs. At this point, the
value of VDDp and VgG conforms to the PIDC for the machine. These values,
as well as Vs, VD and VBIAs are stored in the processor memory.
According to one feature of the present invention, a second
iterative process is controlled by logic means within processor 84, which
compares the measured values of the V0 30 patch to a preset V0~3Ds value.
System illumination is varied to achieve identity of the set and measured
values; convergence establishes a third point on the PIDC. As shown in Figure
~, processor 84 measures the difference between the test value of V.3D and
the V 3DS, set into the processor memory. If V0.30 ~l V.3Ds (no convergence)
processor 84 sends a signal to lamp power supply 51 to vary the output of lamp
42 and to patch generator 53 to erase the V.3D patch 104. Scan carriage 45
repeats the process beginning at the home position 1 and the voltmeter again
measures the charge at patch 104 sencling the output signal to the processor.
This iterative process is controlled by a second algorithm provided in the
Appendix.
Upon convergence of V0.3D and Vo.3DS~ the value of Eo, system
exposure level, is stored. Convergence has assured that the 0.3D voltage also
falls on the PIDC curve shown in Figure 2. Thus, the charge at the high
(VDDp), low (VgG) and intermittent levels all lie along the predetermined
PIDC, thus ensuring that the copy quality will be consistent with machine
population utilizing that particular PIDC.
To summarize the automatic setup procedure to this point, the
basic xerographic parameters of char~e current, illumination level and the
developer bias have been set. The remainder of the setup procedure is
directed to the calibration of the patch generator based on these values and
the adjustment, if necessary, of toner concentration. Figure 9 shows a
functional flow diagram setting forth these steps.
Referring to Figures 5 and 9, and to the timing diagram shown in
Figure 10, scan carriage 45 is moved to the right, past park position 1 to park
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position 2 where it is parked directly beneath a centrally located 0.7 density
target strip 107. A 0.7 patch 108 (Fig. 11) is thus formed along the centerline
of belt 10 conforming in area to strip 107. The carriage then returns to the
home position where a VDDp patch 110 is formed. As patch 110 passes
beneath patch generator 64, the patch is illuminated by a light output from the
generator determined by the bias voltage VpG applied to the patch generator.
The charge level at patch 110 is therefore reduced to level VDpG which is
lower than V0.7D -
Both patches 108 and 110 are developed at development station C
tFigure 1) and pass beneath densitometer 64. As illustrated in Figure I and
Figure 11, the densitometer detects the density of the developed test area and
produces electrical output signals indicative thereof. Thus the densitometer
produces output signals proportional to the toner mass deposited on the V0.7D
patch 108 and the VDpG patch 110. These signals are conveyed to processor
84 through conversion circuitry shown in Figure 3. Processor 83 compares the
two values and if there is a difference (VDss) a signal is generated which
changes the voltage level at the patch generator. The developed patches are
cleaned at cleaning station F, Figure 1, and patches 108 and 110 are laid down
as previously described, developed and again measured by densitometer 64.
Adjustments are made to patch generator 53 in an iterative process governed
by the algorithm set forth in the Appendix until the two measured values are
equal. When this occurs, the patch generator is properly calibrated to the
system parameters and value representing VpG is stored.
The final task of the setup procedure is to adjust the developer
parameters, if necessary. An adjustment may not be necessary since the toner
concentration level is monitored during normal operation and toner period-
ically added, as is known in the art. Therefore, a previous operation cycle
should have left the toner concentration in a proper operating condition.
However, the present setup procedure ensures proper toner concentrations by
comparing the last VDDS value measured and stored by processor 84 with a
previously stored VDSs value representing a value of VDSs which if exceeded,
indicates a low level of toner concentration is present. As shown in Figure 9,
if the difference between the two exceeds a set value, processor 84 activates
toner dispenser motor 63 causing toner dispenser 60 to discharge toner
particles into toner container 62. This increases the concentration of toner
particles in the developer mixture so as to increase the density of subsequent
developed test patches. Carriage 45 forms a subsequent V.70, VDDp patch.
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Densitometer 64 measures the respective density and processor 82 determines
a new VDss value as described above. The new VDSs is compared with the
VDSs set, the process repeated, if necessary. Once the values are within the
predefined diEference range, toner developability parameters have been
5 defined and the automatic setup procedure is terminated. Normal machine
operation then begins.
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A "PENDIX
CONTROLLER ALGO~ITHiMS
(#1~ The grid bias control voltage adjustment for contrast setup is
as f ollows:
v id (n+l)=Vgrid(n)~~{~c(vcntrstset cntrst~}
(#2) The grid bias additive adjustments for the Pictorial Copy
modes (Pmode) are determined as follows:
vgrid add ( mode ) = {kl (f ddp ( P mode ) )~
(#3) The Vddp setpoint for the pictorial modes is as follows:
Vddp (Pmode) = Vddpsu + f ddp (Pmode)
Where fddp for the above two algorithms is:
p ~ddp P mode
fddp( mode) ~ I A - ------ J
Where AesV is the digital resolution of the ESV input.
(#4) The following equation for developer bias can be used for
determining the required bias during ABS (autosetup and customer access
mode) as well as for deteremining Vbiassu:
Vbias = Vbg + vbiaSclnfld
The term Vbg is replaced with Vabsmin during any ABS adjustment
and replaced with vpl 1 during the Vbiassu calculation.
The term vbiasclnfld is the cleaning field in terms of developer
bias. There is a value for each of the normal copy modes. During setup the
value is for CN.
VbiaSclnfld (Mode) [ Gdb
The particular mode is found in the Table "Multinational Standard
Modes" at the end of the Appendix.
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(#5) The illumination control voltage adjustment for the exposure
setup is expressed in terms of bit count as follows:
EO(n+ 1) = EO(n) +~{k2 (V0.3cont ~ C0.3contset)}~
(#6) The pre-developability patch generator adjustment is as
f ollows:
vpgen = vpgen + (k3 ~ vddp - ~ vbia5)
(#7) For the patch generator setup, if the error in the D55
readings is greater ~han 3 bits and the number of iterations is less than 3
(cycles is less than 7), the correction applied is:
vpgen(n+1) = vpgen(n) +~k4 (dssp2 (ave) - dsspO(n~}
(#8) The final adjustment to the patch generator level is as
follows:
Vpgen(n + I) = Vpgen(n)+~k4(V0.7average -(Vbg + Vclnfld) V0.7devset)¦
(#9) The developer bias setpoint for the copy modes is as follows:
vbia5 (Mode) = Vbiassu + fbias (M
Where fbias is
f Fbias ~Ai ode) j
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Multinational Standard Modes
___ . . , . ___ _
Mode FeXp Fbias FddpFpgen Fclean
(v) (v) (v)
CL4 ¦1.4 ~45 0 0.76+ 160
CL3 1.4 + 10 0 0.95+ 125
CL2 1.29 0 0 1.0+105
CL 1 1.14 0 0 1.0 + 90
CN 1.00 O O 1.0 +65
CD 1 0.89 0 0 1.0 + 50
CD2 0.79 0 0 1.0 +20
l S CD3 0.75 - 10 0 1.06 - 5
CD4 l0 75~45 _ 1~ 25 ~ 40
Pictoral Modes
ModeFeXpFbias Fddp FpgenFclean
PL41.32 - 135 - 345 0.00 +30
PL30.93 - 150 - 360 0.00 + 5
PL20.79 - 125 335 0.00 +10
PL 10.71 - 95 - 295 0.03 +25
PN 0.71 - 80 - 245 0.20 +25
PD I0.71 - 65 - 190 0.40 +15
PD20.85 - 65 - 145 0.63 +25
PD31.00 - 65 -100 0.86 +40
PD40.99 - 65 - 55 1.08 +25 I
