U.S. patent number 3,732,003 [Application Number 05/213,013] was granted by the patent office on 1973-05-08 for electrostatographic compensation apparatus.
This patent grant is currently assigned to Eastman Kodak Company. Invention is credited to Conrad Altmann.
United States Patent |
3,732,003 |
Altmann |
May 8, 1973 |
**Please see images for:
( Certificate of Correction ) ** |
ELECTROSTATOGRAPHIC COMPENSATION APPARATUS
Abstract
In an electrostatographic copying device of the type which
utilizes a replaceable web having a particular sensitivity response
which falls into one of a number of sensitivity response ranges,
the particular sensitivity response range of each web being encoded
thereon or on a cartridge in which the web is disposed,
compensation apparatus adapted to alter any one of a number of
operations performed with respect to a utilized web, in a manner
which insures comparable copies when webs of differing sensitivity
are employed from time to time.
Inventors: |
Altmann; Conrad (Rochester,
NY) |
Assignee: |
Eastman Kodak Company
(Rochester, NY)
|
Family
ID: |
22793390 |
Appl.
No.: |
05/213,013 |
Filed: |
December 28, 1971 |
Current U.S.
Class: |
399/46; 355/71;
399/116 |
Current CPC
Class: |
G03G
15/754 (20130101); G03G 15/5033 (20130101) |
Current International
Class: |
G03G
15/00 (20060101); G03g 015/00 () |
Field of
Search: |
;355/3,14,16,71,67
;95/64D |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Greiner; Robert P.
Claims
I claim:
1. In an electrostatographic copying device which utilizes a
replaceable member having a particular sensitivity response with
respect to operations to be performed thereon in the device at the
work stations thereof, the member carrying coded indicia of its
sensitivity response, apparatus for automatically effecting
compensation in the device solely as a function of the sensitivity
response of the utilized member, said apparatus comprising:
a. means for detecting the particular sensitivity response range of
the utilized member and for generating a signal representative
thereof;
b. control means responsive to said signal, cooperably associated
with at least one of the work stations, for achieving compensation
of an associated work station's effect on the utilized member
solely in accordance with the sensitivity response thereof as
represented by said signal; and
c. means for achieving original-to-original document contrast
compensation cooperably associated with any one of the associated
work stations, said control means including means for allowing said
means for achieving and said control means to function
independently of each other.
2. The apparatus according to claim 1 wherein said means for
achieving and said control means are both cooperably associated for
independent compensation with the same work station.
3. The apparatus according to claim 2 wherein the device includes
an exposure control work station and said means for achieving and
said control means are both cooperably associated for independent
compensation therewith.
4. In an electrostatographic device of the type having a plurality
of work stations including an exposure control station located
along an endless operative path and which is adapted to utilize on
the path electrophotosensitive members having a particular
sensitivity response with respect to the operations to be performed
thereon in the device, the members carrying coded indicia of its
sensitivity response, apparatus for automatically effecting
exposure compensation in the device solely as a function of the
sensitivity response of a utilized member, said apparatus
comprising:
a. means for changing the exposure of the utilized member at the
exposure station;
b. sensing means for detecting and decoding the indicia of
sensitivity response associated with the utilized member and for
generating a signal representative thereof; and
c. control means, cooperably associated with said means for
changing and said sensing means, for automatically effecting a
compensatory change in exposure of the utilized member solely in
accordance with the nature of said signal generated by said sensing
means, said means for changing including:
i. a rotatably mounted exposure diaphragm, and
ii. reversible drive means connected to said diaphragm and said
control circuit means.
5. The apparatus according to claim 4 wherein said means for
automatically effecting includes:
a. a plurality of switching means, one each of said switching means
being provided for each of the sensitivity response ranges expected
into which the sensitivity response of a utilized member might
fall, cooperably associated with said means for changing, for
generating a signal when said means for changing has effected an
exposure change in accordance with the particular sensitivity
response range of the utilized web; and
b. control circuit means connected to said means for changing said
sensing means and said plurality of switching means for controlling
said means for changing to effect an exposure change in accordance
with the sensitivity range of the utilized member as represented by
the signals generated by said sensing means and for de-energizing
said drive means in response to the signals generated by said
switching means.
6. The apparatus according to claim 5 wherein said means for
changing includes:
a. a rotatably mounted exposure diaphragm; and
b. reversible drive means connected to said diaphragm and said
control circuit means.
7. The apparatus according to claim 4 wherein said device
additionally includes means for achieving original-to-original
document contrast compensation cooperably associated with the
exposure station, said means for changing including means for
allowing said means for achieving and said means for changing to
function independently of each other.
8. The apparatus according to claim 7 wherein said means for
changing includes:
a. a rotatably mounted exposure diaphragm; and
b. reversible drive means connected to said diaphragm and said
control circuit means.
9. In an electrostatographic device which utilizes a replaceable
web having a particular sensitivity response and carrying coded
indicia of one of the possible sensitivity ranges into which the
particular sensitivity of the utilized web falls, and wherein the
web is disposed in the device about an endless path to be driven
therealong past a plurality of work stations including an exposure
station, apparatus for automatically effecting exposure
compensation as a function of the sensitivity range of the utilized
web, said apparatus comprising:
a. drivable means for changing the exposure of the utilized web at
the exposure station;
b. drive means for driving said means for changing to effect
exposure change;
c. sensing means for decoding the indicia indicating the
sensitivity range of the utilized web and for generating signals
representative thereof;
d. a plurality of switching means, one each of said switching means
being provided for each of the sensitivity ranges expected into
which the sensitivity response of the utilized web might fall,
cooperably associated with said means for changing, for generating
a signal when said means for changing has effected an exposure
change in accordance with the sensitivity range of the utilized
web; and
e. control circuit means connected to said drive means, said
sensing means and said switching means for energizing said drive
means to effect an exposure change in accordance with the
sensitivity range of the utilized web as represented by the signals
generated by said sensing means and for de-energizing said drive
means in response to the signals generated by said switching means.
Description
CROSS-REFERENCE TO RELATED APPLICATION
Reference is hereby made to commonly assigned and copending U.S.
Pat. application Ser. No. 213,014, entitled Control Circuitry For
Assisting Electrostatographic Compensation, filed on Dec. 28, 1971,
in the names of Franklin L. Guyette and Donald R. Frank, now U.S.
Pat. No. 3,700,323.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to electrostatographic copying devices and,
more particularly, to apparatus for automatically effecting
compensation in such devices as a function of the sensitivity
response of a web utilized therein.
2. Description of the Prior Art
Electrostatographic copying devices are known in the art. In one
particular type of such devices, a photosensitive web is utilized,
the operative segments of which are sequentially exposed to an
original document which is to be copied. The exposure step charges
the operative web segments, converting the light image to a latent
electrostatic charge pattern which is subsequently converted to a
visible developed image.
It has been found that, because of manufacturing tolerances, the
photoconductive webs will vary significantly in photosensitivity
response as well as in other properties which affect the quality of
the resultant copies. Consequently, each time a web is changed,
copy quality and comparability will change without compensation
therefor. There is, therefore, a need for compensation apparatus to
overcome the problem of variation in web response.
In the particular type of electrostatographic copying device
described, there is sometimes included automatic or manually
operated exposure control means which are employed to compensate
for differences in the contrast quality of the original documents
to be copied. Such apparatus is used to obtain comparable copies
regardless of differences in contrast from document to document. In
view of this, any compensation introduced to negate copy
differences due to web-to-web sensitivity variations, cannot
interfere with or reduce the effect of the document contrast
compensation.
SUMMARY OF THE INVENTION
It is, therefore, a primary object of the present invention to
provide, in an electrostatographic copying device which utilizes a
sensitized web, automatic compensation for variations in web
sensitivity when a web is changed.
It is a further object of the present invention to provide such web
sensitivity compensation in a manner which will not interfere with
document contrast compensation.
It is an additional object of the present invention to provide such
web sensitivity compensation automatically in response to coded
sensitivity information carried by the web itself or on a cartridge
in which it might be enclosed.
Accordingly, there is provided for use in an electrostatographic
copying device, compensation apparatus for minimizing or negativing
the problem raised by variations in web-to-web sensitivity. One
example of such compensation apparatus is embodied in exposure
compensation apparatus which includes a rotatable plate connected
to the diaphragm of an exposure station in the device, drive means
for rotating the plate to open or close the diaphragm, sensing
means for decoding and translating the sensitivity range of the
utilized web into signals indicative thereof, switching means
cooperably associated with the plate for generating signals
indicative of its movement to a correct exposure position and a
control circuit connected to the drive means, the sensing means and
the switching means for energizing the drive means to effect
movement of the plate to the correct exposure position in
accordance with the indicated sensitivity range of the web and for
de-energizing the drive means in response to a signal from the
switching means indicating that the correct exposure position has
been reached by the plate.
Other objects and advantages of the present invention will become
apparent from the detailed description of the preferred embodiment
set forth in detail below.
BRIEF DESCRIPTION OF THE DRAWINGS
In the detailed description of the preferred embodiment of the
invention presented below, reference is made to the accompanying
drawings in which:
FIG. 1 schematically illustrates an electrostatographic copying
device wherein the present invention is utilized;
FIG. 2 illustrates a cartridge, in which a sensitized web is
disposed, for use in the electrostatographic device of FIG. 1;
FIG. 3 depicts a code sensor, partly broken away for clarity, which
is employed to aid in determining the sensitivity range of a web to
be used as indicated by a coding arrangement thereon;
FIG. 4 schematically illustrates exposure compensation means
according to the present invention aided by the code sensor of FIG.
3 and a control circuit;
FIG. 5 is a side view of the exposure compensation means shown
generally in FIG. 1 and more specifically in FIG. 4;
FIG. 6 is a block diagram of the control circuit shown in FIG. 4;
and
FIG. 7 is a schematic diagram of the constituent elements of the
block diagram of FIG. 6.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the drawings wherein like reference numerals have
been used in the several views to describe like elements, FIG. 1
illustrates an electrostatographic copying device 10 of the type
wherein the present invention can be advantageously used. This
device includes a photosensitive web 12 disposed about a plurality
of rollers 13 and is adapted to be driven thereby along an endless
path through a series of electrophotographic or electrostatographic
work stations.
Electrophotosensitive web 12 is commonly constructed including a
photoconductive layer with a conductive backing carried by a
flexible support such as, for example, a film base. Examples of
such webs and methods for their preparation will be found in
commonly assigned U.S. Pat. No. 3,141,770 issued in the name of
Davis et al. For simplicity, the multilayered construction of web
12 has not been specifically shown in the drawings of this
application.
The electrophotographic or electrostatographic stations of the
device 10 illustrated in FIG. 1, include a charging station 14
whereat a uniform charge is applied to the surface of the
photoconductive layer of web 12, an exposing station 16 whereat the
uniformly charged photoconductive layer of web 12 is exposed to
imagewise projected actinic radiation creating an electrostatic
image thereon, a developing station 18 whereat finely divided toner
particles are applied to the photoconductive layer of web 12
creating a toner image thereon, a transfer station 20 whereat the
toner image is transferred to a surface of receiving sheet 22 and a
cleaning station 24 whereat residual toner is removed from the
surface of web 12 and any remaining electrostatic charge is
dissipated. After passing cleaning station 24, the cleaned
operative segment of electrophotosensitive web 12 is ready for
recycling and reuse.
Transfer sheet 22 carrying the transferred toner image is
subsequently fed to a fixing station 26 where the toner image is
fused yielding a final reproduction. Successive transfer sheets 22
are fed from a supply station 28 to the transfer station 20 and are
discharged therefrom after the fusing operation to a storage
station 30.
It will be understood that the particular apparatus illustrated in
FIG. 1 is merely exemplary and that the invention disclosed and
claimed herein is usable with similar apparatus in which some of
the above-described electrophotographic or electrostatographic work
stations are eliminated, combined with others or substantially
changed or supplemented in function. It will also be understood
that the invention disclosed and claimed herein is usable in
non-electrophotographic apparatus.
By utilizing the device 10 shown in FIG. 1, a large number of
copies can be made by repetitive use of the operative segments of a
single electrophotosensitive web. However, after continued use, the
photoconductive layer of web 12 tends to lose some of its image
transferance properties. This occurs for a number of reasons,
primary of which is the buildup of a small layer of scum as a
result of the repetative developing and cleaning processes. In
order to overcome this degradation of performance of the
photoconductive layer of web 12, a web inserting, removing and/or
replacement station 32 has been provided. The details of operation
of the web replacement station 32 are set forth specifically in
commonly assigned U.S. Pat. application Ser. No. 834,695, filed in
the name of Thaddeus Swanke, filed on June 19, 1969, now U.S. Pat.
No. 3,619,050. For purposes of this description it is sufficient to
appreciate that web replacement is made possible by and takes place
at the web replacement station 32.
As is shown in FIG. 2, the photosensitive web 12 is provided and
disposed within a light-tight cartridge 34. The cartridge 34 is
utilized to store fresh photosensitive webs, such as web 12, and to
receive used webs of the same type for disposal. Cartridge 34
includes a pair of circular end caps 36 and 38, the edges of which
are at least partially overlapped by a coil of protective sheet
material 40. End cap 36 has a "V-shaped" retaining depression
formed in its surface which is adapted to cooperate with a male
dart (not shown) disposed within the web replacement station 32.
The cooperation between the male dart and depression 42 helps
effect proper support and orientation of cartridge 34 upon its
insertion into the web replacement station 32.
The photosensitive web 12 is wound about a core (not shown) with
its leading edge 44 extending out from opening 46. The details of
securement of the protective sheet 40 are set forth in commonly
assigned U.S. Pat. application Ser. No. 835,128, filed in the name
of Clifford B. Bushnell, filed on June 20, 1969, now U.S. Pat. No.
3,645,385.
When actuated by an operator, the mechanism of the web replacement
station 32, as is described in greater detail in the
above-referenced U.S. Pat. application Ser. No. 834,695, opens the
cartridge 34 and positions the leading end 44 of web 12 to be
contacted by a towbar (not shown). The towbar is adapted to engage
leading end 44 and to thread it along the endless path in the
electrostatographic device 10, past the various work stations as
described above. The endless path to be traversed by web 12 in the
apparatus 10 is herein termed the "operative path." Upon completion
of towbar travel around the operative path, means (not shown) are
provided to couple the trailing end (not shown) of web 12 to the
towbar and to splice the leading and trailing ends together,
thereby providing an endless web. Also provided are means (not
shown) which, upon actuation, disengages the web ends and feeds a
used web from the operative path back into cartridge 34.
Also provided in the device 10, and schematically illustrated in
FIGS. 1 and 4, is a document exposure control 50. The document
exposure control 50 is provided to enable an operator to compensate
for vibrations in the contrast quality of a document to be copied.
If, for example, a document having high contrast quality, a
relatively high density range, is to be copied, the document
exposure control 50 is operated to cause a reduction in exposure in
the exposing station 16. If, on the other hand, a document of low
quality contrast, a relatively low density range, is to be copied,
the document exposure control 50 is operated to cause an increase
in exposure in the exposure station 16. It will be noted that the
document exposure control 50 includes three manually operated
pushbuttons 52, 54 and 56, to control exposure respectively for
high, normal and low contrast quality of documents to be copied. It
will be appreciated that the number of pushbuttons can be increased
or decreased depending upon the degree of exposure control
required.
In general, the document exposure control 50 operates in the
following manner. Selection of a particular pushbutton causes
current to be fed to motor 58. Energization of motor 58 causes its
shaft 60 to rotate. Fixedly mounted to shaft 60, as shown in FIG.
4, is a spur gear 62 which rotates with shaft 60. Diaphragm ring
64, which when rotated changes the diaphragm opening 68, includes a
gear segment 66 mounted in meshing engagement with spur gear 62.
Thus, when motor 58 is energized, the diaphragm ring 64 is rotated
thereby opening or closing the diaphragm 70 which increases or
decreases diaphragm opening 68 varying the exposure in accordance
with the contrast quality of the document to be copied.
More specifically, the document exposure control 50 operates in the
following manner. Corresponding to each of the document contrast
quality pushbuttons 52, 54, and 56, is a diaphragm position or
limit switch 74, 76 and 78 respectively. As shown in FIG. 4,
diaphragm ring 64 is positioned with its switch cam 72 engaging
limit switch 76, the switch, in this example, which corresponds to
a normal document contrast quality range. If, at this point, it was
desired to copy a document of low quality contrast, then the
corresponding pushbutton 52 for such a document would be actuated.
This would result in motor 58 being energized by a control circuit
(not shown) which is responsive to signals from the pushbuttons 52,
54 and 56. The control circuit can be similar to control circuit
102, the details of which are hereinafter explained, or it can be
of any suitable type.
Upon receipt of a signal from pushbuttons 52, 54 or 56, the control
circuit causes motor 58 to be energized, which, in turn, causes the
diaphragm ring 64 to be rotated until limit switch 78 is actuated
by the cam 72. Actuation of limit switch 78 is sensed by the
control circuit which shuts off current flow to motor 58. The
movement of diaphragm ring 64 from its "normal" to its "low"
contrast positions, results in the diaphragm 70 being opened by a
sufficient amount to compensate for the difference in document
contrast quality. As a result, this increase in exposure allows
comparable copies to be made regardless of the difference in
original document contrast quality.
In a similar manner, assuming a copy was desired from a document of
high contrast quality, the corresponding pushbutton 56 would be
selected. The control circuit, in response, would cause the
diaphragm ring 64 to be driven to where cam 72 would actuate limit
switch 74. The resultant counterclockwise rotation of diaphragm
ring 64 would close diaphragm 70 by a sufficient amount to
compensate for the difference in document contrast quality. As a
result, this decrease in exposure allows comparable copies to be
made regardless of the difference in original document contrast
quality.
It will be appreciated by those having skill in this art, that in
this instance satisfactory exposure compensation is obtained by
varying only the size of the diaphragm opening. However, such
exposure compensation can be achieved by varying the time of
exposure to even the intensity of the illumination in exposure
station 16, or some combination of these exposure factors. That is,
the signals received from the document exposure control station 50
could be utilized to control the speed of a shutter moving across
the optical path or the filament voltage of the illuminating source
or both. Alternatively, such signals can be employed to vary, by
way of example, the charge applied to the photosensitive web 12 at
the charging station 14 or to vary development at developing
station 20 to compensate, as required, for differences in original
document contrast quality from document to document. It should be
further appreciated that such compensation can be manually
initiated, as in the preferred embodiment, or can be automatically
initiated by means of appropriate circuitry cooperably connected to
sensing devices, such as photocells.
Because of manufacturing tolerances, the web 12 will not always
exhibit the same photosensitivity. In addition, other web 12
properties, such as its static charge behavior, are affected in and
varied by the particular manufacturing processes employed. If such
variations are not compensated for, it will be difficult, if not
impossible, to achieve comparable copies of a given document where
different webs are used. In recognition of this problem, the
disclosed apparatus provides a mechanism for achieving
photosensitivity and other compensation which is operable without
effect upon document contrast quality compensation.
As noted above, variations in web sensitivity can cause variations
in copy quality, where such copies are prepared in an
electrostatographic copying device which utilizes such
photosensitive webs. In recognition of this problem, photosensitive
webs intended for such use are tested and sorted into three
sensitivity ranges; slow, normal and fast, respectively, which
cover the manufacturing range. It will be appreciated that,
depending upon the degree of copy comparability desired from web to
web, the number of sensitivity ranges can be increased or decreased
as required. For purposes of this description, the number of
sensitivity ranges has been arbitrarily fixed at three. It will be
further appreciated that the webs can be divided, as well, into
ranges which indicate their charge transferance response. Thus, for
example, a web which has "fast" photosensitivity response may
exhibit a "slow" acceptance of static charge response. Such a web
may then be placed into a "normal" range, which would be indicative
of the totality of its response in the device 10.
In the preferred embodiment, the cartridges 34 in which the
photosensitive webs 12 are packaged for use carry a precoded
indication of the particular sensitivity range of the included web.
As shown in FIG. 2, cartridge 34 carries on its surface a coding
location 80 which consists of coding positions 82 and 84. The
particular sensitivity range for a web 12 included therein is
indicated by placing a strip of tape in either or both of coding
positions 82 and 84. Alternatively, a black mark can be printed or
painted in either or both of coding positions 82 or 84. In the
arrangement of the preferred embodiment, a non-reflective strip of
tape 83 is employed to cover the reflective surface of a cartridge
34 at its coding positions 82 and 84. It will be realized that the
roles of the tape and cartridge surface can be readily reversed,
that is, the tape surface can be made reflective and the cartridge
surface made non-reflective. It is also important to note that the
coding location 80 can be formed on or carried by the web 12
itself, rather than by the cartridge 34.
Since coding location 80 can accommodate two non-reflective strips
of tape 83, the absence or presence of one or both of these strips
is indicative of the possible sensitivity range of the web. In the
preferred embodiment, as shown in FIG. 2, a strip of tape 83,
affixed to coding position 84, is utilized to indicate the "slow"
range of web sensitivity. Affixing the strip of tape 83 instead to
coding position 82, indicates a web having photosensitivity falling
into the "fast" range. Finally, a cartridge 34 carrying a web
having "normal" sensitivity, does not carry a strip of tape 83 at
either of the coding positions 82 and 84. Those having skill in
this art will appreciate that other variants of the preferred
coding scheme can be used to identify the web sensitivity ranges to
be encountered and that other coding indicia, such as, for example,
notches on the cartridges, can be utilized in place of the tape
strips 83. Furthermore, it should be appreciated that the
particular coding scheme which is utilized can be encoded so that
the totality of web response, above and beyond its photosensitivity
response, is accounted for.
When a cartridge 34 is properly inserted and oriented in the web
replacement station 32, its coding location 80 faces a code sensor
86, which is most clearly illustrated in FIG. 3. Code sensor 86
includes a housing 88 having three openings 90, 92 and 94 formed
therein. Mounted within the outwardly tapered housing opening 92 is
lamp 96 which serves to illuminate the coding location 80. Mounted
respectively within openings 90 and 94, are photosensors 98 and
100. Openings 90 and 94 are aligned with the respective
corresponding coding positions 84 and 82. Consequently,
illumination from lamp 96 will be reflected therefrom to impinge
upon photosensors 98 and 100 in the absence of a tape strip 83.
The presence of a tape strip 83 in coding position 82, signifying a
"slow" sensitivity web, prevents illumination from impinging upon
photosensor 100. Similarly, the presence of a tape strip 83 in
coding position 84, signifying a "fast" sensitivity web, prevents
illumination from impinging upon photosensor 98. As will
hereinafter be described in greater detail, the "darkening" of
either photosensor 98 or 100 causes control circuit 102 to drive
the diaphragm ring 64 to a position appropriate for the sensitivity
range of the web to be used.
As shown in FIGS. 4 and 5, motor 58 and switches 74, 76 and 78, are
mounted on a switch plate 104. Mounted adjacent switch plate 104 is
motor 106 having a shaft 108 to which cam 110 is eccentrically
mounted. Motor 106 is positioned so that cam 110 fits within a slot
112 in switch plate 104, slot 112 being only slightly larger than
the diameter of cam 110.
Energization of motor 106 causes cam 110 to be rotated which, in
turn, drives switch plate 104. Mounted adjacent switch plate 104
are limit switches 114, 116 and 118, which correspond respectively
to the "slow," "fast" and "normal" sensitivity ranges of the
photosensitive webs. Switch cams 120, 122 and 124 formed on switch
plate 104 actuate switches 114, 116 and 118, respectively, as
switch plate 104 is rotated by the driving action of the
eccentrically mounted cam 112. The switches 114, 116 and 118 and
the switch cams 120, 122 and 124 are respectively arranged or
spaced so that only one of the switches can be actuated at a
particular time by its associated switch cam.
When switch plate 104 is thusly rotated, motor 58 and switches 74,
76 and 78 which are mounted thereon, are also moved. Because of the
internal gearing of motor 58, its shaft 60 is rather difficult to
turn when motor 58 is de-energized. As a result, the movement of
switch plate 104 in a clockwise direction causes spur gear 62 to
move the gear segment 66 in a clockwise direction. This movement
rotates the diaphragm ring 64 and increases the size of diaphragm
opening 68 to compensate for a "slow" sensitivity web. Since the
switches 74, 76 and 78 and switch cam 72 are all rotated through
the same angle, along with diaphragm ring 64, the range of document
contrast quality compensation is merely shifted and not disturbed.
Similarly, counterclockwise movement of switch plate 104 causes the
diaphragm ring 64 to be rotated in the same direction thereby
decreasing the size of diaphragm opening 68. Such movement
compensates for a "fast" sensitivity web without disturbing the
range of document contrast quality compensation. By way of review,
it should be noted that energization of motor 58 will have no
effect on the position of switch plate 104 although it will cause,
as previously noted, an independent change in the size of diaphragm
opening 68 in accordance with the contrast quality of the document
to be copied.
Control circuit 102 operates, in response to the sensing of an
encoded web response, in the following manner. A block diagram of
control circuit 102 is illustrated in FIG. 6. A recognition trigger
circuit, 121 and 123, is provided for each of the sensitivity
ranges, other than the "normal" response range, to be encountered.
Thus, in general, if there are n sensitivity ranges, there will be
"n minus one" recognition trigger circuits. It will be appreciated
that depending upon the particular coding scheme selected, the
sensitivity range for which a recognition trigger circuit is not
provided, need not be a median or a "normal" sensitivity range.
In the described embodiment, recognition trigger circuit 121 is
actuated by radiation from lamp 96 in response to the presence of a
web 12 having "slow" sensitivity response. Similarly, recognition
trigger circuit 123 is actuated by radiation from lamp 96 in
response to the detection of a web 12 having a "fast" sensitivity
response. When actuated, as shall hereinafter be described in
greater detail, recognition trigger circuits 121 or 123 cause
respectively, the "slow" response switching circuit 131 or the
"fast" response switching 133 to actuate the exposure control drive
circuit 137. When so actuated, the exposure control drive circuit
137, in turn, causes energization of an exposure control drive 139
which adjusts one of the exposure factors in accordance with the
decoded response of the included web 12.
At the same time, when proper exposure in accordance with the
sensitivity response of the included web 12 is obtained, the
response switching circuit, 131 or 133 in the described embodiment,
which has caused energization of the exposure control drive 139 is
disenabled. This shuts down the exposure control drive circuit 137
and holds exposure compensation at the required level.
When a "normal" sensitivity range web 12 is utilized, both
recognition trigger circuits 121 and 123 are actuated. In addition
to the above-mentioned responses of the response switching circuits
131 and 133, the exposure control drive circuit 137 and the
exposure control drive 139, the "normal" response switching circuit
135, which acts as a logical AND circuit, is also actuated. When
the proper exposure compensation for a "normal" web is obtained, if
any is required, the "normal" response switching circuit turns off
the exposure control drive circuit 137 thereby halting further
exposure compensation by the exposure control drive 139.
Control circuit 102, which is utilized to control operation of
motor 106 in response to the detected sensitivity range of a web
12, is schematically illustrated in FIG. 7. Control circuit 102
operates in the following detailed manner. Power is supplied
continuously from the indicated sources when the main power switch
(not shown) of the device 10 is turned on. This causes current flow
through lamp 96 and readies the code sensor 86. With lamp 96
illuminated, but no cartridge 34 inserted in the web replacement
station 32, photosensors 98 and 100 are in the "dark" and exhibit
very high resistive values. Consequently, the junction 125 of the
voltage dividers formed by photosensor 100 and resistor 134 and the
junction 127 of the voltage are held relatively positive. With
junctions 125 and 127 so biased, the base-emitter junctions of
transistors 126, 130, 138 and 140 are reversed biased maintaining
these transistors in a "cut-off" or non-conducting condition. In
addition, with photosensors 98 and 100 in the "dark," transistors
148 and 152 are also maintained in a "cut-off" condition.
It is assumed, at this point, for explanatory purposes that a
cartridge 34 carrying a web 12 which falls into the "slow"
sensitivity range and is so coded, has been inserted into the web
replacement station 32. As previously noted, a "slow" range web 12
carries a tape strip 83 at coding position 84. This prevents
illumination from reaching photosensor 98, while allowing
illumination to impinge upon photosensor 100. Thus, junction 127 is
held at its original bias condition while junction 125, due to the
decrease in resistive value exhibited by photosensor 100 when
illuminated and the higher relative value of resistor 134 with
respect thereto, approaches the -12.sup.v supply in value. This
forward biases the emitter-base junctions of transistors 126 and
130, which are thereby turned on, allowing current to flow through
relay coil K2, which closes relay contacts K2-1 and K2-2. It is
also important to note that the coding location 80 can be formed on
or carried by the web 12 itself, rather than by the cartridge
34.
When relay contacts K2-1 close, current flow from the +4.sup.v
supply through the voltage divider network formed by resistors 141
and 144 is initiated. This causes the junction 129 of the resistors
141 and 144 to swing towards the -12.sup.v supply in value, turning
on the motor drive transistor 148 by forward biasing its
emitter-base junction. When this happens, current flows through the
blocking diode 150 and turns on motor 106.
Energization of motor 106 causes the eccentrically mounted cam 110
to rotate in slot 112. When cam 120 contacts normally closed switch
114, that switch is opened, returning junction 129 to its quiescent
value which reverse biases drive transistor 148. With drive
transistor 148 now cut off, current flow to motor 106 ceases and
the motor 106 is turned off. Thus, for a "slow" range sensitivity
web 12, the switch plate 104 is rotated, and with it the diaphragm
opening 68 is enlarged, thereby compensating for the slower
photosensitivity of the web 12 to be used.
In a similar manner, insertion of a cartridge 34 carrying a web 12
which has a photosensitivity response falling into the "fast" range
into the web replacement station 32, causes transistors 138 and 140
to be biased on. This results in current flow through relay K1,
closing relay contacts K1-1 and K1-2. The closing of relay contacts
K1-1 turns on drive transistor 148, which initiates drive by motor
106, until cam 122 contacts the normally closed switch 116. When
this occurs, motor drive ceases with the diaphragm opening 68
having been reduced by an amount sufficient to compensate for the
quicker photosensitive response of the web 12 to be used.
Finally, when a cartridge 34 carrying a web 12 which exhibits a
photosensitivity response falling into the "normal" range is
inserted into the web replacement station 32, both photosensors 98
and 100 are illuminated. This causes transistors 126, 130, 138 and
140 to be turned on, drawing current through both relay K1 and
relay K2. The resultant closing of relay contacts K1-1 and K2-2
turns on drive transistor 148. Motor 106 is thereby energized and
continues drive until the normally open switch 118 is contacted and
closed by cam 124. When switch 118 is closed, and since relay
contacts K1-2 and K2-2 are now both closed, current flow from the
+12.sup.v supply through resistor 146 is initiated. When this
occurs, because of the predetermined selection of the relative
values of resistors 141 and 146, junction 129 is made sufficiently
positive with respect to the base of drive transistor 148 to turn
that transistor off. When drive transistor 148 is thusly cut off,
motor 106 ceases to drive the switch plate 104 which has been
rotated an amount sufficient to bring diaphragm opening 68 to a
size which correctly corresponds to a "normal" sensitivity web
12.
It should be noted that if a "slow" web 12 replaces another "slow"
one, or a "fast" web replaces another "fast" web, or if a "normal"
web replaces a web of like sensitivity, motor 106 will not be
energized since cam 120 will have opened and kept open switch 114,
or cam 122 will have opened and kept open switch 116, or cam 124
will have closed and kept closed switch 118, respectively.
Finally, with respect to FIG. 7, it should be noted that transistor
152 serves to dynamically brake motor 106 by providing a discharge
path for its back e.m.f. In a similar manner, diodes 132 and 142
provide discharge paths for the reverse currents generated by the
collapsing fields of relays K1 and K2 which result when transistors
130 and 140 are turned off.
As noted with respect to the document exposure control 50,
compensation in an electrostatographic copying device 10 of the
type shown and described herein can be achieved in a number of
ways. In a similar manner, the signals derived from code sensor 86
can be utilized to automatically adjust or modify the effect of any
one of the work stations upon the utilized web 12. Thus, for
example, the signals indicative of the sensitivity response of the
utilized web can be employed to effect exposure compensation in a
manner other than that set forth above (i.e. -- shutter or filament
voltage control). Alternatively, such signals can be used to vary
the charge applied to the web at charging station 14 or to vary
development at development station 20.
The invention has been described in detail with particular
reference to a preferred embodiment thereof, but it will be
understood that variations and modifications can be effected within
the spirit and scope of the invention.
* * * * *