U.S. patent number 3,917,396 [Application Number 05/438,972] was granted by the patent office on 1975-11-04 for control system.
This patent grant is currently assigned to Xerox Corporation. Invention is credited to James M. Donohue, Daniel L. Mueller.
United States Patent |
3,917,396 |
Donohue , et al. |
November 4, 1975 |
**Please see images for:
( Certificate of Correction ) ** |
Control system
Abstract
A control system for controlling the processing steps of an
electrostatic printing machine including means for generating a
series train of clock pulses, means for generating a series train
of start or reset pulses and control logic responsive to the reset
and clock pulses to generate a plurality of timed control signals
for implementing certain of the processing steps. A transfer
roller, the linear surface speed of which is synchronized with the
moving speed of the photoreceptor, may be used to generate the
reset pulses for the successive cycle of processing operation. The
intervals between the successive reset pulses, called pitches, are
in effect marked by the clock pulses, some of which are by used to
generate the timed control signals.
Inventors: |
Donohue; James M. (Rochester,
NY), Mueller; Daniel L. (Fairport, NY) |
Assignee: |
Xerox Corporation (Stamford,
CT)
|
Family
ID: |
26793595 |
Appl.
No.: |
05/438,972 |
Filed: |
February 4, 1974 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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244734 |
Apr 12, 1972 |
3796486 |
Mar 12, 1974 |
|
|
97745 |
Dec 14, 1970 |
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Current U.S.
Class: |
399/78 |
Current CPC
Class: |
G03G
21/145 (20130101); G05B 19/07 (20130101); G05B
2219/25267 (20130101) |
Current International
Class: |
G05B
19/04 (20060101); G03G 21/14 (20060101); G05B
19/07 (20060101); G03G 015/00 () |
Field of
Search: |
;355/14 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Horan; John M.
Parent Case Text
This is a continuation-in-part application of a copending
application, Ser. No. 244,734, filed on Apr. 12, 1972, which was
allowed in July 1973, and was granted on Mar. 12, 1974 as U.S. Pat.
No. 3,796,486. The copending application was, in turn, a
continuation application, Ser. No. 97,745, filed on Dec. 14, 1970.
Claims
What is claimed is:
1. A processing system for producing copies of an original having
an endless movable photoreceptor belt including,
means for producing latent images on said belt,
development means for applying developing material to each of the
latent images to develop the same,
a transfer station adjacent the moving belt,
means for feeding seriatim sheets of copy material at the rate of
one sheet per actuation thereof from a supply thereof and to said
transfer station at which each developed image is transferred to
said sheets,
means for generating in equal cycles series of control pulses, said
generating means including means associated with said image
producing means and said sheet feeding means for controlling
actuation of the latter in timed sequence relative to the
production of each latent image by said image producing means for
each of said cycles, wherein said generating means is a timing
device, and
means responsive to the speed of movement of the belt for resetting
each of said time cycles wherein said pulse generating means is
arranged to respond to a preselected one of the processing steps
that is dependent upon and related to the speed of the machine
drive.
2. A processing system for reproducing copies of an original having
an endless movable photoreceptor belt including,
means for producing electrostatic latent images on said belt,
development means for applying developing material to each of the
latent images to develop the same,
a transfer station adjacent the moving belt,
means for feeding seriatim sheets of copy material at the rate of
one sheet per actuation thereof from a supply thereof and to said
transfer station at which each developed image is transferred to
said sheets,
means for generating in equal cycles series of control pulses, said
generating means including means associated with said image
producing means and said sheet feeding means for controlling
actuation of the latter in timed sequence relative the production
of each latent image by said image producing means for each of said
cycles,
a transfer roller adjacent the transfer station for supporting each
sheet of material in contact with the belt during transfer of
developed images, said roller having a peripheral rotative speed
equal to the speed of movement of the belt,
said generating means being operatively connected to said roller
for producing operation of the former during rotation of the
latter, wherein said set signal generating means is arranged to
respond to a selected one of the processing steps that is
independent of and unrelated to the speed of the machine drive.
3. An electrostatographic system for making copies on copy sheets
comprising:
a machine including means for implementing a plurality of
electrostatographic copying steps for making copies;
means for driving said machine at a given speed;
means for generating a train of clock pulses related to said speed
of said drive means;
means for generating set signals determined by at least one
recurring state of said machine;
control means responsive to said clock pulses and said set signals
for generating a series of control signals said control signals
occurring after a predetermined number of clock pulses are counted
starting from an occurrence of a one of said set signals, each of
said control signals activating a related one of said
electrostatographic step implementing means.
4. The system according to claim 3, wherein said control means is
adapted to process a plurality of processing steps necessary to
increase throughput to make a plurality of copies at any given
moment to increase throughput capacity of the machine.
5. The system according to claim 3, said means for generating said
set signals is adapted to respond to a selected one of the
processing steps occurrence of which is time independent of the
machine drive speed so that the process is rendered flexible and
independent of the machine drive speed.
6. In an electrophotographic apparatus having an elongated
electrophotosensitive member adapted to have an electrostatic image
formed, on a surface thereof, and means for transferring
information contained in such image to a receiver sheet in image
transfer relation with the member, the combination comprising:
a. a plurality of actuable work stations operative when actuated
for forming an electrostatic image on the surface portion of the
member, and for feeding the receiver sheet into image transfer
relation with such electrostatic image formed on the member;
b. means for moving the member along an endless path relative to
said plurality of actuable work stations; and
c. means for sequentially actuating and de-actuating said work
stations in timed relation to movement of the member past
predetermined positions along said path comprising:
i. a shift register coupled to said electrophotosenstive member
moving means and having a plurality of states, the present state of
which is a function of the position of the member along the endless
path;
ii. means coupled to said moving means and effective to produce
clock signals in response to movement of the member along the
path;
iii. counter means independent of said shift register and
responsive to said clock signals and having a plurality of states,
the present state of which is representative of the total
cumulative number of said clock signals; and
iv. means coupled to said counter means and said shift register and
responsive to particular ones of the present states of said shift
register and particular ones of the present states of said counter
means to effect sequential operation of said work stations with
respect to said surface of the member during movement of the member
along the endless path respectively.
7. The electrophotographic apparatus according to claim 6 in which
one of said work stations comprises an exposure station operative
when actuated to form an electrostatic image on said member.
8. The electrophotographic apparatus according to claim 6 in which
one of said work stations comprises an actuable sheet feeder
operative when actuated for feeding said receiver sheet.
9. In an electrostatographic apparatus having a photoreceptor means
adapted to have an electrostatic image formed thereon and means for
transferring such image to a support member, the combination
comprising:
a. a plurality of actuable work stations including exposure,
transfer stations and a support member feeding station,
b. means for moving said photoreceptor means along an endless path
past said actuable work stations, and
c. control means for actuating at least one of said actuable work
stations in timed relation to the movement of said photoreceptor
means therepast, said control means comprising:
i. means for generating a train of set pulses at the rate the
images are to be made,
ii. a shift register responsive to said train of set pulses and
having a plurality of states, the present state of which is
function of the positions of the images on said photoreceptive
means,
iii. means responsive to the movement of said photoreceptor means
and effective to produce a train of clock pulses at a frequency
which is a function of the movement of said photoreceptive means
and faster than repetition rate of said set pulses by at least an
order of magnitude,
iv. counter means independent of said shift register and responsive
to said clock signals and reset in response to each of said set
pulses and having a plurality of states, the present state of which
is representative of selected cumulative counts of said clock
pulses, and
v. logic means responsive to selected ones of the present states of
said shift register and said counter means for generating control
signals to operate selected ones of said plurality of said actuable
stations timed operation in sequence.
10. In a reproducing machine wherein a plurality of actuable means
are used to implement steps for making copies in succession, the
improvement which comprises control means having:
means for generating a train of pitch pulses the repetition rate of
which is a function of the rate at which the machine is configured
to make the copies,
means for generating a train of clock pulses at a rate which is
higher than the rate of said train of pitch pulses by an order of
magnitude,
means responsive to said train of pitch and clock pulses for
counting said clock pulses per pulse period of said train of pitch
pulses and deriving timed control signals for actuating at least
one of said actuable means once per said pulse period of said train
of pitch pulses in successive cycles for making the copies, and
a driven photoreceptive member on which images of an original are
formed in succession and a driven roller the peripheral speed of
which travels at substantially the same speed as the driven
photoreceptive member for transferring the images onto copy sheets
in succession, said means for generating said train of pitch pulses
operatively coupled to said roller for generating said pitch
pulses.
11. The machine according to claim 10, including means for driving
said photoreceptive member, means operatively coupled to said
driving means for generating said train of clock pulses related to
the distance of travel of said member.
12. The machine according to claim 10, including means for driving
said photoreceptive member, means operatively coupled to said
driving means for generating said train of clock pulses related to
the movement of said photoreceptive member.
13. In a reproducing machine wherein a plurality of actuable means
are used to implement steps for making copies in succession, the
improvement of which comprises control means;
means for generating a train of pitch pulses the repetition rate of
which is a function of the rate at which the machine is configured
to make the copies,
means for generating a train of clock pulses at a rate which is
higher than the rate of said train of pitch pulses by an order of
magnitude, and
means responsive to said train of pitch and clock pulses for
counting said clock pulses per pulse period of said train of pitch
pulses and deriving timed control signals for actuating at least
one of said actuable means once per said pulse period of said train
of pitch pulses in successive cycles for making the copies,
a driven photoreceptive means, said plurality of actuable stations
having means for forming and developing electrostatic latent images
in succession on said photoreceptor means,
means for transferring the images onto a copy substrate,
means for feeding the copy substrates in succession onto said
transferring means said rate at which said machine is configured to
make copies determining a rate of feeding said copy substrates onto
said transferring means.
14. The system according to claim 13, wherein said photoreceptor
means includes an endless photoreceptive belt, and including
means for driving said photoreceptor belt at a constant speed,
means for forming images in succession on said driven
photoreceptive belt,
means for feeding copy sheets in succession,
means for transferring said images onto corresponding copy sheets
in succession, and
said timed control signal deriving means is adapted to generate
said timed control signals in successive cycles, wherein cycle of
control signals started by a corresponding one of pitch pulses and
wherein timing of each of the control signals is derived from said
train of clock pulses which relate to the travel distance of said
photoreceptive belt.
15. The system according to claim 14, wherein said timed control
signal deriving means includes a counting means, a shift register,
and logic means operatively connected to derive said timed control
signals in response to said clock and pitch pulses.
16. A process control system for controlling an operation of a
system designed to produce end products in succession at a given
production rate wherein component parts that form the end products
are fed past actuable stations positioned along a process path and
wherein selected ones of actuable stations have to be actuated in a
timed sequence wherein the said process path is divisible in terms
of zones so spaced that the parts traversing through respective
zones at the production rate of the system, comprising:
means for generating a train of set pulses the repetition rate of
which is set at the production rate and wherein each of the set
pulses is timed so that they occur at the start of each of the
successive cycles,
means for providing a train of clock pulses, the repetition rate of
which is set substantially faster than that of said train of set
pulses,
means responsive to said train of set pulses and clock pulses for
deriving control signals timed to occur in successive cycles for
actuating said selected ones of said actuable stations, whereby the
end products are made in succession wherein said system is adapted
to control an electrostatographic copier/duplicator machine
including a copy sheet path along which copy sheets are transported
and a xerographic path with a plurality of actuable stations
positioned therealong for implementing process events of forming,
developing and transferring of latent electrostatic images onto the
copy substrates in succession, means for driving said photoreceptor
means to traverse along said xerographic path at a given speed,
wherein said means for generating said train of set pulses is
adapted to generate said set pulses timed to occur at the rate the
developed images are transferred to the substrates and said clock
pulse generating means is adapted to generate said clock pulses so
that the repetition rate thereof is time related to the travel
distance of movement of said photoreceptor means.
17. The control system according to claim 16, including
asynchronous logic means for generating control signals for
actuating certain selected ones of actuable stations asynchronously
with said set and clock pulses.
Description
This invention relates to a control system for processing machines
and, particularly, to an improved control system for electrostatic
reproducing machines.
Electrostatic printing machines of the endless belt type employ
various processing stations that uniformly charge, expose, develop,
transfer, clean, etc. during any cycle of copying. For high speed
operation of these machines, it becomes very important that there
be a proper base for the timing sequence of operation of the
processing stations in order to maintain proper registration of the
processing functions relative to images. In controlling the
operation of the machine, there must be provisions for efficient
and reliable movement of sheets of copy paper along the paper path
of the machine and in particular for timely presentation of the
sheets in succession to the transfer station of the machine in
timed sequence relative to the production of electrostatic latent
images for the proper orientation of each sheet of the developed
image received at the transfer station, and for assuring timely
removal of each sheet at a precise time in order to effect
continued movement of each sheet for further processing thereof,
and for reliable means to detect jam conditions.
Likewise, there must be provisions for efficient and reliable
movement of photoconductor belt or medium past various
electrostatographic processing stations such as charging, exposing,
developing and transferring stations and controlling the actuation
of certain of these stations in a timely manner so that when a
developed image is presented for transfer to the paper sheet, it is
properly registered.
Therefore, the principal object of the present invention is to
provide an improved control means for processing machines in
general and, in particular, provide an improved control means for
electrostatographic reproducing machines.
Another object of the present invention is to maintain proper
timing of the operation of the electrostatographic processing
stations in the machine so as to effect maximum efficiency in the
operation of the machines, especially of the type designed for high
speed reproduction.
Yet another object of the present invention is to improve the
throughput capacity of the machine.
Still another object of the present invention is to render the
machine more versatile, flexible and reliable.
In accordance with the present invention, the foregoing objects of
the invention are attained by a control system having means for
providing a series train of clock pulses, means for generating
reset or start pulses in succesion for each of the processing
cycles, and logic means for generating a plurality of timed control
signals derived from the start and clock pulses for enabling
various processing stations to implement the machine processing
steps timely.
In accordance with a feature of the present invention, the timed
sequence of control signals for operating certain processing
stations is based upon start or reset pulses keyed to the
displacement or position of the photoreceptor belt or medium which
is sensed by a speed responsive element preferably in the form of
the transfer roller used for transferring the image to the copy
sheet.
According to yet another feature of the invention, the control
system is adapted to generate more than one cycle of enabling
pulses to process more than one copying process in the machine at
any given moment. The foregoing and other objects and features will
become apparent from the following detailed description of
illustrative embodiments of the present invention in conjunction
with the accompanying drawings, in which:
FIG. 1 shows a schematic sectional view of an electrostatic
reproduction machine embodying the principles of the invention;
FIG. 2 shows an illustrative example of a control system according
to the present invention;
FIG. 3 shows a schematic view similar to the one shown in FIG. 1
simplified to illustrate control principles of the present
invention;
FIG. 4 shows graphic illustrations of various aspects of the
principles involved in the control system according to the present
invention; and
FIG. 5 shows a schematic illustration of a bottling process in
which the control system of the present invention may be utilized
as illustrative of the broad scope of applicability of the present
invention.
DETAILED DESCRIPTION
Basic principles and features of the control system according to
the present invention will be described principally in terms of
operating a xerographic machine, such as the one schematically
illustrated in FIG. 1. But is is to be understood clearly from the
outset that the nature and the scope of the present invention is
not intended to be limited to the operation of xerographic copying
machines. It is not only applicable to other types of reproducing
machines but also more broadly to any types of processing machines
or systems requiring control means. A xerographic machine is used
merely for the purpose of facilitating one's understanding of the
principles and features of the present invention and is not
intended to limit the scope of the present invention to the
xerographic copier/duplicator technology.
Now for a general understanding of an electrostatic processing
system, in which the invention may be incorporated, reference is
had to FIG. 1 in which various components of a xerographic
reproducing system are schematically illustrated. As in all
xerographic reproducing systems of the type illustrated, a light
image of an original to be reproduced is projected onto the
sensitized surface of a xerographic plate to form an electrostatic
latent image thereon. Thereafter, the latent image is developed
with an oppositely charged developing material comprising carrier
beads and smaller toner particles triboelectrically adhering
thereto to form a xerographic powder image, corresponding to the
latent image on the plate surface. The powder image is then
electrostatically transferred to a support surface to which it may
be fixed by a fusing device whereby the powder image is caused
permanently to adhere to the support surface.
The electrostatically attractable developing material commonly used
in magnetic brush developing apparatus comprises a pigmented
resinous powder referred to here as "toner" and a "carrier" of
larger granular beads formed with steel cores coated with a
material removed in the triboelectric series from the toner so that
a triboelectric charge is generated between the toner powder and
the granular carrier. The magnetizable carrier also provides
mechanical control for the formation of brush bristles by virtue of
magnetic fields so that the toner can be readily handled and
brought into contact with the exposed xerographic surface. The
toner is then attracted to the electrostatic latent image from the
carrier bristles to produce a visible powder image on an insulating
surface.
In the illustrated machine, an original D to be copied is placed
upon a transparent support platen P fixedly arranged in an
illumination assembly generally indicated by the reference numeral
11. While upon the platen, an illumination system flashes light
rays upon the original thereby producing image rays corresponding
to the informational areas on the original. The image rays are
projected by means of an optical system 11 to an exposure station A
for exposing the photosensitive surface of a moving xerographic
plate in the form of a flexible photoconductive belt 12. In moving
in the direction indicated by the arrow, prior to reaching the
exposure station A, that portion of the belt being exposed would
have been uniformly charged by a corona device 13 located at a belt
run extending between belt supporting rollers 14 and 15. The
exposure station extends between the roller 14 and a third support
roller 16, and the belt run between these rollers is encompassed
entirely by the exposure station for minimizing the space needed
for the belt and its supporting rollers.
The exposure of the belt surface to the light image discharges the
photoconductive layer in the areas struck by light, whereby there
remains on the belt a latent electrostatic image in image
configuration corresponding to the light image projected from the
original on the supporting platen. As the belt surface continues
its movement, the electrostatic image passes around the roller 16
and through a developing station B located at a third run of the
belt and in which there is positioned a developing apparatus
generally indicated by the reference numeral 17. Suitable means
(not shown) such as, vacuum panels or tensioning means, may be
utilized for maintaining the belt flat in all three belt runs, and
additionally the belt run related to the development zone B is
maintained at an inclined plane. The developing apparatus 17
comprises a plurality of magnetic brushes which carry developing
material to the adjacent surface of the upwardly moving inclined
photoconductive belt 12 in order to provide development of the
electrostatic image.
As the developing material is applied to the xerographic belt,
toner particles in the development material are attracted
electrostatically to the belt surface to form powder images. As
toner powder images are formed, additional toner particles are
supplied to the developing material in proportion to the amount of
toner deposited on the belt during xerographic processing. For this
purpose, a toner dispenser generally indicated by reference numeral
18 is used to accurately meter toner, upon demand, to the developer
material in the developing apparatus 17.
The developed electrostatic image is transported by the belt 12 to
a transfer station C located at a point of tangency on the belt as
it moves around the roller 15 whereat a sheet of copy paper is
moved at a speed in synchronism with the moving belt in order to
accomplish transfer of the developer image. There is provided at
this station a transfer roller 19 which is arranged on the frame of
the machine for contacting the non-transfer side of each sheet of
copy paper as the same is brought into transfer engagement with the
belt 12. The roller 19 is electrically biased with sufficient
voltage so that a developed image on the belt 12 may be
electrostatically transferred to the adjacent side of a sheet of
paper S, as the same is brought into contact therewith, and also
for tacking the same on the roller 19.
A stripping finger or air puffing device 21 utilized for stripping
the sheet from the roller is provided to permit pickup and
continued movement of the sheet by a vacuum conveying system 22.
Each sheet of paper travels only a short distance before being
stripped therefrom by the stripper 21. Devices such as gripper bars
and release elements mounted on the roller 19 may be utilized
instead of the stripper 21 for gripping the leading edge of each
sheet of copy paper to ensure proper positioning thereon and to
effect the release of a copy sheet at a precise time so as to strip
the same for pickup by a conveying system. The timing of the
release of each edge relative to the sheet separation from the
supply stack of sheets may be for the same period of time.
There is also provided a suitable sheet transport mechanism adapted
to transport sheets of paper seriatim from a paper handling
mechanism generally indicated by the reference numeral 23 to the
developed image on the belt being carried around the roller 15. The
developed image on the belt 12, presented at the transfer station C
in timed sequence and in registration with the arrival of a sheet
of paper, is transferred to the sheet. The sheet is then stripped
and forwarded toward the fusing station. Since the belt 12 may slip
on its supporting rollers during high speed use, or the belt may
have an undesirable transverse seam, it is preferred that the
registration be directly related to the belt. This is accomplished
by utilizing the transfer roller 19 which is directly applied to
the belt and moves at all times directly therewith. A resetting
mechanism is operatively coupled with the roller so that it resets
for each revolution of the roller. The diameter of the roller 19
may be dimensioned so as to be slightly greater than the width of a
sheet of paper being applied thereto in order to provide for the
sheet width and desired spacing between sheets. The application of
each sheet to the roller at precisely the same position for all
sheets, may be utilized as the point or start, reset, or zero time
for timing of each copying cycle. If another diameter is utilized
for the roller 19, the circumference must be factored into image
length so that reset is accomplished in the space equal to the
width of a sheet of copy paper plus a little spacing distance
between sheets. Control (FIG. 1: L; FIG. 2), as will be explained
more fully below in generating flashing signals so the imaging
means 11 form latent images on the belt at the imaging station A in
successive sequence in timed relation to the start or reset pulses.
Since the photoreceptor belt 12 is continuously being exposed by
flasing imaging rays, it may contain a number of electrostatic
latent images, for example, five images between the exposure and
transfer stations.
Similarly, the paper path between the paper feeding apparatus 23
and the transfer station may contain two or more sheets. Any number
of process cycles are put into control L and register timing means
operably coupled to the roller 19 concurrently at any given moment
once the machine is initialized. Starting from zero on reset time,
the stripper 21 may be activated to detack the leading edge of a
sheet of paper from the roller 19, this sheet having been
previously separated from the paper supply stack and advanced to
the transfer station. The next operation in time may involve a
flash exposure of the belt at the exposure station. The developed
image being transferred commencing at the zero time of the present
cycle may have had its exposure some five timing cycles previously.
As the present timing cycle continues, the stripping device 21 may
be activated again so as to strip the leading edge of another sheet
away from the roller 19. As this roller continues to rotate it
provides succession of reset pulses to the timing device T.
After the sheet is stripped from the belt 12, it is conveyed by the
conveying system 22 into a fuser assembly generally indicated by
the reference numeral 24 wherein the developed and transferred
xerographic powder image on the sheet material is permanently
affixed thereto. After fusing, the finished copy is discharged from
the apparatus at a suitable point for collection externally of the
apparatus.
The remaining toner particles remaining as residue on the developed
images, background particles and those particles otherwise not
transferred are carried by the belt 12 to a cleaning apparatus 25
positioned on the run of the belt between the rollers 14, 15
adjacent the charging device 13. THe cleaning device comprises a
rotating brush, a corotron for neutralizing charges remaining on
the particles and discharge lamp for discharging any remaining
electrostatic charges on the belt. It will be appreciated that the
run of the belt adjacent the cleaning device is at an inclined
angle relative to the horizontal as this run leaves the uppermost
roller 15 where a developed image is transferred. Such an
arrangement maintains the relatively straight line of copy sheet
movement which operatively cooperates with the belt 12 at its
highest point. The belt is then uniformly charged again at the
charging station 13 for subsequent operations of exposure,
development, etc. Now the control system for the electrostatic
printing machine described above in conjunction with FIG. 1 will be
described in detail in conjunction with FIGS. 2, 3 and 4. But
before the system is described, it will be helpful to review
briefly prior art control systems for processing machines such as
xerographic reproducing machines. Heretofore, the control systems
have relied on mechanical or electromechanical control means
largely in running its operation. With the advances in electronic
technology, more recently, there has been a trend in the industry
to use more of electronic control logic circuitry in controlling
the machine operations. However, so far the conversion process has
tended to be mere substitution of mechanical or electromechanical
elements with functionally corresponding electronic logic elements.
Thus, for example, typically, in the older machines for deriving
timing signals of the operation of various process steps such as
charging, imaging, developing, transferring and fusing, etc., a
bank of cams integrally mounted on the drive shaft of the machine
apertured discs axially mounted on the shaft that chops a light
source and photodetecting means that detects the chopped light were
used. Thus, according to the prior art, in deriving the control
signals, the control system relied on the machine drive mechanism
and slaved the timing of the control signals to the mechanical
limitations of the drive mechanism itself and its rotational speed.
This is adequate to run a simple processing system with a single
process path requiring a drive motor and relatively simple set of
processing steps. But where more than one process path is involved
and/or where any number of process steps must be controlled, the
prior art scheme has become inadequate unwieldly and unreliable.
The inadequacy gets all the more serious where some of the process
paths or parts thereof are asynchronous. The inadequacy gets quite
acute when the throughput capacity is increased significantly and
some of the process steps take different time durations than others
and some steps require precise timing whereas others do not, as is
the case with high speed copier/duplicator machines, an example of
which is described above in conjunction with FIG. 1.
Now a control system that avoids or overcomes much of the above
mentioned and other shortcomings of the prior art will be described
with reference to an illustrative embodiment shown in FIG. 2. As
illustrated, the control system may comprise two main functional
setions; an asynchronous section 41 and a synchronous section 42.
The asynchronous section is designed to respond to various input
signals of the type that will be described and generate control
signals necessary to start, run and shut down the machine process.
The synchronous logic section 42 is designed to generate control
signals which must be precisely timed so that they implement the
processing steps that require precise timing.
Referring to the first section, it includes an asynchronous or
untimed control logic 41 of a suitable conventional design which
provides the control signals necessary for the machine to start
when a set of predetermined conditions are met or in proper states,
shuts the machine down when an undesired condition is encountered
or when a programmer 43 that programs copy runs (i.e., number of
copies, mode of copy collation, etc.) indicates that the count of
the copies made and indicated by a counter 42 equals the desired
number of copies dialed in or programmed by a copy number selector
45.
The logic 41 is of a design that also provides control signals that
are necessary to condition the machine so that the paper can be
fed, transported, processed and that are necessary to condition
certain of the xerographic processing stations so that they are
ready to operate.
The initial conditioning steps may also include housekeeping chores
such as getting the fusing station heated up to an operating
temperature, checking whether or not there is enough paper supply,
getting the paper station (FIG. 1, 46) ready to feed the paper
sheets into the paper path, etc. These initializing and
housekeeping signals are provided via suitable output path 47 to
the corresponding processing or implementing stations (not
shown).
When the initializing conditions are met, the asynchronous or
untimed control section 41 initiates the copy run when the print
button 61 is pushed. The intitializing conditions may be a set of
inputs signifying readiness of the machine such as the fact that
the paper is not at a low supply condition (64), that the machine
is in the standby mode, that the fuser is up to the temperature
(65), that the platen cover is down to a proper position (68), and
that the jam condition (80) do not exist. The asynchronous control
logic section 41 operates asynchronously with the xerographic
processing steps because the aforementioned types of initializing
conditions or housekeeping chores signifying the readiness of the
machine need not be in synchronism with the machine operation.
Hence the logic 41 need not be synchronous with the rest of machine
operation. It could be synchronous with the rest of the machine
process, if the particular processing system or machine is of such
a nature and the initializing and housekeeping chores must be
performed synchronously with the process steps.
The asynchronous control section 41 produces the necessary control
signals to start the machine and run it with the help of timed
signals from the controlled logic section 42. It also generates a
stop print signal from the programmer 43 when the copy run is
complete at which point it initiates the shutdown cycle. The
shutdown cycle entails the steps of processing out the remaining
images in the paper path and the xerographic processing path. After
this the control 41 reverts the machine to the standby mode.
In response to the emergency conditions, such as, low paper supply
or platen disengagement, logic 41 initiates the shutdown cycle. The
asynchronous logic 41 may be of such design that, in the presence
of a jam signal (80), it will shut down the affected portion of the
machine immediately in order to prevent damage to the machine by
the jammed sheet of paper. In the presence of, or in the condition
that requires an immediate shutdown of the entire machine, it will
bring the entire machine to a "hard" or abrupt stop. Thus, in the
case of a jam occurring as a copy sheet is about to reach the fuser
station 24 (FIG. 1), it will stop the machine immediately to
prevent feeding of the sheet into the fusing station. Suitable
interlocking means 87 may be operatively connected in series with a
power on/off switch 88 as a safety measure.
The second section includes synchronous or timed logic 42 having a
shift register 49, a counter 51, and a logic matrix 53 operatively
connected to provide a plurality of precisely timed control signals
for actuating or implementing the various machine processing steps
that require precisely timed operation in their successive cycles
of operation.
Referring to FIG. 1, the events or processing steps that require
the precise timing in the process are, such as, the flashing of the
light to form an electrostatic image on the imageing station A and
transferring the image to the copy sheet S at the transferring
station C by the transfer roller 19, in the xerographic process. In
the paper path, the paper sheet must be registered or presented,
that is, it must arrive at the transfer roller at a right moment so
that the image being transferred is properly centered in the copy
sheet. Other signals that may require precise timing may be the
monitoring functions, such as, jam detection signals along the
paper path so that they are monitored at the right time in the
process cycles.
The control system described broadly above is similar in the
functional sense to those of the prior art machine in that it
provides a plurality of enabling control signals for implementing
their known processing steps. However, the present control system
is uniquely different in the manner in which the implementation
take place. Generally, stated the system utilizes two trains of
pulses for deriving the necessary timing information for giving the
precision to the occurrence of the control signals that require
precision timing.
Referring to FIG. 2, one train of pulses is derived from a high
speed clock pulse generator 50 and the other from a pulse generator
52 which come at a slower rate. The first or higher speed clock may
be derived from any suitable means and may be related to the drive
speed of the machine main drive such as the motor M that drives the
photoconductor belt 12. The slower speed pulse generator 52 may be
derived from the timing pulse generator (FIG. 1, T) provided by the
roller 19 or a suitable registering means that registers the
arrival of the lead edge of the paper sheet at a point near the
transfer roll 19.
While the pulse generating means 50 and 52 may be operatively
associated with the machine drive means or the paper transfer
roller, as described above, they need not be so limited or tied
down, as shall be described in detail later. These two trains of
pulses are applied to the logic matrix 53 of the timed logic setion
42 via the shift register 49 and the counter 51 respectively and
the logic matrix 53, in response, generates the timed control
signals. As will be explained in detail hereinafter the timed logic
section 42 keeps track of the sheets and the images in progression
in the paper and photoconductor paths respectively from the two
trains of pulses and generates the timed control signals and sends
them out to their corresponding process step implementing means in
the output paths 91,92, etc.
The high speed clock source 50 may be of any suitable design, such
as, for example, a magnetic pickoff device that picks off the clock
pulses from the predetermined number of gear teeth disposed at the
periphery of a disc mounted axially on the drve shaft of the main
drive motor M, as the shaft rotates. The clock pulse generator 50
may also be of a photodetecting arrangement of a suitable type that
detects the chopped light by an apertured disc that may be mounted
axially on the drive shaft of the main motor M as the shaft
rotates. The clock pulses so derived is related to the speed of the
motor M that controls the speed of the photoconductor belt 12.
But the clock generator 50 need not be coupled to the drive shaft
of the motor. It can be from any suitable source, such as a regular
60 hertz power supply line or even an independent crystal
oxcillator. The important thing to note is that the clock pulses
generated by the clock 50 maintains its frequency at a given rate
and maintains a certain fixed relationship to the speed of the
photoconductor belt, that is, the speed at which the xerographic
machine drive motor M rotates. The high speed clock pulses are
applied to the counter 51. The counter 51 in turn counts and
applies the count signal to the logic matrix 53.
The second clock source 52 may be derived from a suitable means
which generates pulse signals, the timing of which can be used as a
key, start, or bench mark of each of the imaging process cycles. It
is important to note that the selected event is of such a nature
that it can be used as a bench mark or a start of each of the
imaging process cycles. Thus, the imaging step or image
transferring step in the xerographic process can be used as the
reset or start signal since they are keyed to the xerographic steps
in terms of timing. Hence, more specifically, the registration of
the lead edge of the paper sheet at a point just prior to or at the
point of contact between the transfer roller 19 and photoconductor
belt 12 may be used, because other xerographic processing steps in
the photoconductor belt must be related back to this merging
step.
In the alternative, the start or reset or registration pulses could
be derived from the photoconductor belt 12 itself as follows: the
photoconductor may be provided with a number of equally spaced
apertures along an edge thereof to correspond to the spacing of
successive images. A photodetecting means TD may be positioned at a
suitable location to detect a light beam as it is chopped by the
travelling belt 12. This signal may be used as a train of the reset
or start signals. Or the reference or the reset pulse may be
derived from the timing of the exposure pulses at the imaging
stations. These reset or start pulses so generated by the pulse
generating means 52 are applied to the shift register 49. Note that
each of the pulses represent and correspond to the successive
images being formed and traversing through in the xerographic
path.
Referring to the shift register, the first stage F1 of the process
shift register is made a part of the asynchronous logic section 41
and is not clocked by the reset pulses. When the asynchronous
control logic decides that the conditions are right and that the
machine processing steps can be initiated, it generates and
provides an enabling signal in the form of logical 1 to the shift
register F1. This sets the shift register 49 in condition to
respond to the reset pulses coming from the reset pulse generator
52. In response, the shift register 49 shifts the pulses down to
the right in succession in a well known manner. The progression of
the logical 1 along the shift register represents the progression
or the movement of the leading edges of the images past certain
points in the xerographic process. The shift register 49, in turn,
provides logical signals to the logic matrix 53 signifying the
procession of the images in the xerographic process path. The logic
matrix is of a suitable design that derives, from the output of the
high speed counter 51 and the shift register 49, precisely timed
control signals in succession and applies them to the implementing
means via the output paths 91, 92, etc.
It is noted here in passing that most of the working components,
such as the asynchronous control section 41, the shift register 49,
the counter 51 and the logic matrix 53 may be made of digital
integrated circuit logic or large scale integrated circuits (LSI)
presently available from any number of manufacturers. Use of such
logic circuits offers decided advantages over the prior art
mechanical or electromechanical or discrete logic elements from the
standpoint of cost, reliability, versatility, power consumption,
speed, size, etc.
The aforementioned control system will now be described from
another viewpoint in order to highlight and focus on the
timing/spatial relationship of the processing steps that recognizes
and utilizes of such a relationship in evolving a control system
that is superior over the prior art control systems in terms of its
reliability, flexibility, cost, etc., or more generally in terms of
any usual criteria measuring the quality of such a system.
The relationship will now be described with reference to FIGS. 3
and 4. Referring to FIG. 3, there is shown the electrostatic or
xerographic processing machine of FIG. 1, stripped of most
mechanical and other elements, but retaining the key elements which
are necessary to show the xerographic or phootoconductor and paper
paths. FIG. 4 shows conceptual representation of the spatial and
timing relationship of the xerographic path and paper path. It also
gives a pictorial representation of clocks that illustrate the
timing/spatial relationship.
In the xerographic process path, the photoconductor belt 12 is
shown rotating counterclockwise at a uniform speed as it is driven
by the motor M. The belt passes various processing stations, such
as the exposure A, development stations B, the transfer C, charging
13 stations. The paper path is shown to include the paper feeding
station 23, transfer station C and the fusing station 24.
In analyzing the processing steps in the paper path and the
xerographic path, the following characteristics are found: Certain
steps such as, the imaging, the image transferring and feedinng of
the paper at the transferring station are precisely timed. Also the
monitoring steps such as the detection of the jam conditions along
the paper path or detection of the undesired presence of the sheet
on the selenium belt SOS (FIG. 4), are precisely timed during the
machine process.
However, there are other events or process steps which have to take
place in a certain sequence but which do not require precise
timing. Thus, the developing of the image at the imaging station B,
the charging of the photoconductor belt at the charging station 13
and the feeding of the paper at the feeding station 23, etc., need
not be as precisely timed as imaging, etc., though they must occur
in a certain sequence.
Still another phenomena observed in the processing system is that
the movement of the paper in the paper path need not be at the same
speed as that of the photoconductor belt 12, except at the point
where image is transferred. Notice than in the paper path, the
travel of the paper need not be maintained at a uniform speed as
the paper traverses its path. Thus, the paper may be brought up
very speedily to the registration point. But at the registration
point it must be fed into the transfer roller at the same rate as
the rate at which the photoconductor belt travels. After the image
transfer takes place and the paper leaves the roller, it may then
travel at any speed to the fusing station 24 and so on. What is
critical is that at the transfer station, the paper travels
synchronously with the traveling speed of the image on the
photoconductor belt 12.
FIG. 4 graphically represents the foregoing phenomena. Note that
the xerographic path and paper path are subdivided into a uniformly
spaced sections or `pitches`. The spatial sections relate to the
timing of the images being processed. More specifically, for
example, the xerographic path may be divided into a given number of
zones, sections I.sub.x through VII.sub.x. The paper path may be
analogously divided into seven zones, or sections I.sub.p through
VII.sub.p.
In the xerographic path the physical distance tranversed by the
image across the successive zones are the same because the belt 12
travels at a constant speed. But the physical spacing in the paper
path do not correspond to the speed with which paper travels
because the paper travels at different speeds in different zones
along its path. In FIG. 4, the actual spacings or distances between
the zones in the paper path is in effect shrunk or stretched to
correspond to the corresponding photoconductor belt path zones to
show their timing relationship. Because or the uniformity involved,
the physical spacing or zones in the photoconductor path are used
as the reference path in the present control system.
Now note that within each of the zones or sections certain
processing steps occur. Thus, referring to FIGS. 3 and 4, in the
xerographic path, the exposure takes place at the zone I.sub.x, the
development takes place at the zone III.sub.x, the cleaning takes
place at the zone VI.sub.x, and charging at zone VII.sub.x. And, in
the paper path, the paper is fed at the zone I.sub.p, the paper is
registered at the zone IV.sub.p, the image is transferred at zone
V.sub.p, and the fusing takes place at zone VII.sub.p. Now in terms
of timing relationship, note that certain of these events must take
place at a particular point and space in time in these zones, as
the images are formed and travel with the photoconductor path,
transferred to the paper and then travels along the paper path, as
noted by the path IMPTH. In terms of timing relationship, note that
the events or steps taking place in these zones take place
concurrently.
Now in order to highlight this relationship, clocking signals are
graphically represented by clocks for each zone in FIG. 4. These
clocks may be imagined as a series of clock which clocks the events
happening in the respective zones. They are however, set to the
same time standard. The hour hand of these seven clocks move
synchronously and they signify imaging cycles and hence, their
advances to succeeding hours signify new image processing cycles.
So when the machine is fully loaded, seven imaging processes or
seven copying of processes occur in various stages concurrently at
any given moment.
Now referring to each zone, specific events taking place within
that zone may be analogized to the minute handle. For example, in
zone I, the paper feed takes as the minute arm travels to about
30.degree. angle in the paper path. Sometime later the image
exposure takes place at the imaging station A in the xerographic
process (or photoconductor) path. This takes place precisely, at a
certain point in time, say, for example, as the minute arm travels
past 180.degree. position. Sometime later, for example 35 minute
position or 310.degree. travel later, a jam sensing or detection
operation takes place. Now, in zone IV concurrently with zone I,
the registration of the paper takes place at the 25 minute or the
150.degree. position whereas the image transfer takes place, say,
at 10 minute position or 300.degree. later. And so on, various
events or steps take place concurrently in the seven zones
shown.
Now note that sequence of events such as exposure, registration,
image transfer, jam detection, and detection of the sheet on the
selenium (SOS) take place at precisely timed positions and these
steps are signified by the vertical arrows in FIG. 4. On the other
hand, there are certain events such as development, cleaning,
charging, paper feeding, fusing, etc., that need not be as
precisely timed as the exposure or image transfer step and they are
shown in broken horizontal lines.
The fore going spatial and timing relationship is utilized in the
present control system illustrated in FIG. 2. The control system
shown in FIG. 2 will be described again. But this time in the
context of the aforementioned systems spatial and timing
relationship.
Referring to FIGS. 1 and 2, the reset pulses are derived from the
transfer roller 19 or from the paper registration means as stated
before. Note that spacing of the reset pulses correspond to the
spatial zones in the photoconductor path wherein the registration
or transfer points are shown in zone V.
Now in FIG. 2, the flip flops F1-F7 of the shift register 49 could
be considered graduations, each representing a zone in FIG. 4 and
analogous to foot markings in a ruler and the high speed pulses
from the high speed clock pulse 50 may be analogized to the inch
markings within each foot or zone in the ruler. Now on a ruler the
inch marking restarts at zero as one progresses to the next foot;
likewise the high speed counter which corresponds to the inch
markings is reset to zero each time the lower speed counter or the
shift register shifts one flip flop or section to the right
corresponding to the movement of the image from one zone to the
next. To determine where the location of a point on the ruler is,
one looks at the foot section and the inch markings. Analogously,
the logic matrix 53 looks at the shift register 49 and the counter
51 to derive similar information, i.e., the gross timing, in terms
of zone information from the ON/OFF condition of particular flip
flop and refined timing from the pulse counts from the counter 51
within the corresponding zone.
So, to determine where an image leading edge is along the belt
path, one looks at the shift register and determines which zone it
is and looks at the output of the counter 51 which corresponds to
the precise positioning of the leading edge.
Another way of perceiving the control system from the point of view
of the spatial and timing relationship may be as follows. The
xerographic process path and the paper process path are divided
into pitches, each pitch corresponding to an image spacing or zone
indicated above. Each pitch on the photoconductor belt 12 is at
least as wide as the image one wishes to form. Now each zone or
each shift register is therefore analogous and corresponds to each
pitch whereas the count outputs from the high speed counter 51 is
analogous to a "residue" within each pitch. So events or steps take
place in each zone as the image or the paper that zone or pitch.
This precession or progression is signified by the shifting down of
the flip flops F1-F7 in response to the reset pulses from the
counter 51.
It is important to note that the pulses from the clock 50 and 52
represent positions of the images that are being processed in the
zones of the belt concurrently, as the belt with electrostatic
images on it moves past these zones. But the positions of
processing stations, such as the imaging station A, development
station B and the transfer station C, etc. themselves to not move
any more than the markings on an unmoving ruler move. The point is,
that, the images move past the ruler not the ruler past the points.
The individual shift registers represent the pitch lengths around
the belt path and the content of the individual shift registers
signifies the presence or absence of the lead edge of an image in
that zone.
It should be noted that both clocks are distance or space dependent
and not real time dependent. Since the motor driving the
photoconductor belt 12 can vary somewhat in speed, there may not be
any direct relationship between these clocks and the drive speed
representing the real time. These clocks are also directly related
to the travel of the images in the paper path after the transfer.
In the paper path, the paper travels at different speeds in
different zones but the path is divided so the paper takes the same
amount of time in traversing each zone.
The logic matrix 53 compares the conditions of the shift register
output and the clock output 51. When the shift register and the
clock output indicate that the leading edge of an image has arrived
at a point where a timed event or step must take place such as
flash image transfer respectively or register, etc., the logic
matrix generates a timed control signal therefor.
The matrix senses this fact and sends out a pulse for implementing
that step. This takes place for each image. So up to seven images
represented by these seven flipflops F1-F7 are monitored and timed
signals are sent out for each of the seven zones or images
concurrently.
There are functions that need to come only within the accuracy of
pitches such as cleaning, charging and the fusing operations. These
control functions may be timed by just looking at the shift
register and checking whether they are turned on and off. These
functions remain on ON during the steady state operation of the
machine. On the other hand, the operations controlled by the logic
matrix 53 are of such a nature that they are turned on and off at
particular points in time in the processing pitch during the steady
state operations of the machine as well as the cycle on and off
operations.
The control scheme used in the present control system can be very
advantageously used to detect jam conditions by tracing where the
leading edge of any sheet of paper should be at any particular
time. The control system can monitor or check leading edges of
sheets traveling through the paper path and thereby check jam
conditions.
Refering to FIG. 3 a certain point x in the paper path may be
checked to sense whether or not the paper has been fed. The point Y
in the path may be checked to test mispuff or the failure of the
paper from coming off of the transfer roller 19, and the point Z
just prior to the fusing station, may be checked also. The logic
matrix derives the jam condition signal when it checks at these
points and fails to detect the presence of the lead edge of the
paper itself at these positions. Thus, what the control logic 42
does is that it checks that there is no paper present just before
the sheet should arrive at a location and then checks to see that
the sheet has arrived when it should. If either of these conditions
are not satisfied, then the matrix applies a jam signal to the
machine. The machine, in turn, may be hard stopped or cycled out
depending upon the position and timing of the jam signal. If the
jam occurs before the paper reaches the fuser, the main machine is
made to stop immediately and held to a standby condition to prevent
the paper from being fed into the fuser and cause a fire hazard. On
the other hand, if the jam which signifies that the paper is still
in the fuser, then the machine is made to cycle out that paper from
the fuser before it is stopped and held to a standby condition.
In operation, as apparent from the foregoing description, the
controller system monitors and senses various sets of inputs,
certain of which are used by the asynchronous logic section in
generating signals that are necessary to initialize and start the
machine, run the machine with the help of the output of the timed
control signals from the synchronous logic section and put the
machine into the shut down cycle when appropriate. Thus, the
control system is designed so that the processing paths are treated
as if they comprise a given number of sections or zones and key
timing of the control signals to the imaging cycles on the
revolving photoconductor belt, in terms of spatial and timing
relationship described above. The control system is designed so
that when the machine is loaded fully with a given number of images
for example, seven images, it monitors simultaneously all the
images in progression at various stages in various zones or
pitches; the synchronous control logic section looks at each of the
zones concurrently and generates timed control signals for use in
each zone or for each imaging cycle in progression in each zone.
Thus, when the processing machine is fully loaded the timed control
logic section derives the timed control signals for the various
zones concurrently, where the timing of the control signals in each
zone is in effect timed by separate clocks, while all of the clocks
are held to the same time standard. Thus, referring to FIG. 4, for
example, during a particular pitch or imaging cycle the timed
control logic section generates the following sequence of timed
control signals all in one pitch time interval or imaging cycle;
transfer control signal in zone V for transferring the image to a
corresponding sheet at the transfer station C, paper feed signal
zone I in the paper path and jam sense signal in zone VII in the
paper path, and the sensing signal for the sheet on selenium in
zone VI, the exposure signal forming the image in zone V on the
photoconductor belt, and jam detect signal in the paper path in
zone I, and so forth. Note here that an imaging cycle is merely
intended to mean a cyclical time interval that corresponds to a
time period for a lead edge of the image to traverse a particular
zone.
Another phenomenon observed is that while the pitch intervals are
fixed by the reset or start pulses and are keyed to the imaging
cycle on the photoconductor belt, the high speed pulse train need
not be precisely keyed. Thus, for example, the high speed pulses
may be 1,000 pulses .+-. a given number, say 5 or 10 pulses per
pitch interval, that is all of the pitch intervals need not be
precisely divided equally. What is important is that the count
clock starts at the beginning of each pitch and that the high speed
counter and the logic matrix counts these pulses and at particular
counts the timed control derive signals. The number of pulses
within each pitch time interval depends upon the degree of
resolution with which one wishes to obtain in giving the precision
to the timing of the control signals.
While the control system according to the present invention has
been described in the context of the electrostatographic copying
machine and copying processes above with reference to FIGS. 1
through 4, clearly the nature of the Applicants' control system is
such that it is not limited in terms of its applicability, to
controlling the copying machine processes. It may very well be
applied to any type of processes that entail the controlling of the
process steps and events. Thus, as represented in FIG. 5, a
bottling process involving filling of bottles, labeling them,
counting the labeled bottles and then putting a predetermined
number of bottles in successive containers may also be controlled
by the Applicants' control system with some modifications. Looking
at FIG. 5 more closely, the bottling processes may be for bottling
high priced perfumes or liquors. Suppose it is bottling of high
priced precious perfume and it is important to measure out or
dispense very precise amounts into each bottle, cap them and label
them precisely with fancy multi-colored labels, count them and
package them into packages each, say 12 each in boxes. This may
entail steps of advancing bottles in succession, to the dispensing
station A where the precise amount of perfume is measured and put
into the bottles and then capping them at the station B, labeling
them at station C, counting and packing them at stations D and
E.
While the FIG. 5 shows schematically that the bottles in process
are conveyed by a conveyor belt, it need not be so limited
obviously. It could very well be that these bottles are transported
along peripheral locations of one or more turret type conveying
means where the movement of the bottles are maintained at uniform
speeds at the respective conveying means.
Referring to FIG. 5 closely, the bottles are, however, not always
in motion. At the working stations either they may be held in a
stationary position for a given period of time as is the case when
the bottles are filled at the station A and capped at the station
B, in succession they may be rotated about their axis in succession
while held urgingly against a planar surface holding the labels fed
by a suitable means feeding the labels in succession one at a time
to coincide with the arrival of the bottles in succession. At this
station when the bottle arrives, the label for that bottle is held
at a stationary position and the bottle is gripped and rotated
against the label clockwise as shown so that the label is wrapped
around the bottle. The labels may be pre-gummed so that when the
bottle is rotated therearound, they will adhere to the bottle. Note
that at the labeling station a number of timed events take place
that must be properly sequenced and accurately timed. The foregoing
bottling process involves the following general phenomena. Some of
the process steps have to be precisely timed whereas other steps
need be timed only grossly. For example, the filling of the bottles
require precise measurement; this may be done by precisely timing
the start and stop of filling operation and controlling the flow
rate of the liquid. Likewise, the labeling operation where the
labels have to be brought in succession and each label has to be
stopped for a precise duration while another mechanism holds and
rotates the bottle against the labels. Some of the events or steps
need not be timed as precisely; thus, for example, the counting and
packing at stations D and E need not be precisely timed.
Realizing the foregoing, one may divide the entire process path
into a given number of zones or pitches, for example, five, as
illustrated in FIG. 4. So looking at the five zones or pitches,
what is taking place is that at zone I, the arrival of the bottle
is detected and then the bottle is placed at the filling station A
and the filling is started at a precise time and is stopped at a
precise given time interval later. At zone I the bottle is filled
and at zone II the bottle is capped, and at zone III the bottle is
labeled where the precise timing of a sequence of steps are
required as stated before. At zone or pitch V, the bottles are
counted four at a time and pushed forward in sets into a waiting
box and when three sets are placed, the filled box is moved out of
the way.
Now referring to an application of the Applicant's control system,
the events or steps such as capping and counting of the bottles may
be grossly timed by the shift register 49 output. Various precisely
timed control steps required in labeling and measuring steps
require further precision within each pitch. For this, the high
speed count output and the pitch count are used by the logic matrix
to generate precisely timed control signals.
For registration or reset pulses that register the occurrence of
the bottling cycle, a detecting means DT that detects the movement
of the bottle entering the filling station may be used. For high
resolution timing, any suitable clock may be used within any number
of clock pulses per each pitch interval the number of clock or
pulses being dependent entirely on the precision or resolution with
which one wishes to control these timed events. The logic matrix 53
is adapted to provide, in response to the reset and clock count
signals pulses, output signals which are precisely timed to control
these precisely timed process steps such as certain steps required
in the measuring and the labeling stations.
In summary the present invention is directed to a control system
where a process system may comprise one or more process paths, the
input components parts are processed through the paths and merged
in producing final products, and some of the process need to be
timed in a gross sense while others must be precisely timed in any
one or more of the process paths. In controlling these events or
processing steps, the present control system provides one train of
pulses set to provide pitch signals that correspond to gross timing
and that represent subdivisions or processing paths into zones or
pitches where events or steps occur concurrently in various stages
of progression and another another train of pulses the frequency of
which is related to the resolution or accuracy with whcih the
timing of the certain events or process events in the various zones
or pitches must be precisely timed and controlled. Made of a set of
flip-flop are used for deriving the pitch information and a high
speed counter and a logic matrix are used to respond to the two
pulse trains and derive the precisely timed control signals.
While the invention has been described primarily in terms of an
electrostatographic copying process and then briefly in terms of
its applicability to a bottling process, the present invention
invention is broadly applicable to many different machine
processing systems. Therefore, other modifications or changes may
be made by a person of ordinary skill without departing from the
spirit and scope of the principles of the invention described
above.
* * * * *