Optional output for test patches

An electrographic copy machine of the type having an image transfer member, means for producing document images in an image area of the image transfer member, and means for producing test patch images on the image transfer member is disclosed. The machine includes apparatus for selectively controlling whether or not the test patch images are transferred from the image transfer member to the copy sheets by selectively aligning or not aligning the copy sheets and the test patches on the image transfer member and effecting the transfer of images from the image transfer member to a copy sheet aligned with the images to be transferred, whereby the copy sheets receive or do not receive images of the test patches in accordance with the relative positions of the copy sheets and the test patches on the image transfer member.

FIELD OF THE INVENTION 
This invention relates to test patches useful in controlling image density 
parameters in electrographic machines, and more specifically to apparatus 
for selectably reproducing the test patches on copy sheets produced by the 
machines. 
DESCRIPTION OF THE PRIOR ART 
In electrographic machines such as printers and copiers, control of image 
density is required to produce copied images having constant and 
predeterminable image densities. Parameters which determine image density 
include charger energization, exposure energy, development voltage bias, 
toner concentration in the developer mixture, and image transfer 
potential. 
These are image density parameter control methods known in the prior art 
wherein at least two test patches of different latent image potentials are 
formed on respective portions of a non-image area of an image transfer 
member. The patches are developed, and the resulting toner densities of 
the patches are measured by a sensor. The sensor output is coupled to a 
circuit used to control the image density parameters. 
Because such test patches are intended principally for use with automatic 
adjusting means, they are generally positioned out of the image area of 
the image transfer member. However, some operators may find it desirable 
to see reproductions of the patches on each output copy. Other operators 
may find it sufficient to see the reproductions only occasionally (i.e., 
for example, every 50th copy), and still other operators may never want to 
see the patches. Therefore, it would be highly desirable to provide means 
to selectively either reproduce or not reproduce the test patches on 
copies in accordance with the operator's wishes. 
SUMMARY OF THE INVENTION 
The present invention is useful in electrographic copy machines having 
means for producing document images in an image area of a image transfer 
member and means for producing test patches on the image transfer member. 
In accordance with the invention, apparatus is provided for selectively 
controlling whether or not the test patch images are transferred from the 
image transfer member to the copy sheets by selectively aligning or not 
aligning the copy sheets and the test patches on the image transfer 
member, whereby the copy sheets receive or do not receive images of the 
test patches in accordance with the relative positions of the copy sheets 
and the test patches. 
Several embodiments of the present invention are disclosed herein. In one 
embodiment, the test patches are exposed on the image transfer member 
laterally (cross-track) of the image areas, and the electrographic copy 
machine includes means for selectively shifting copy sheets laterally of 
the image transfer member to overlie or not overlie the test patches. In 
another embodiment, the test patches are exposed on the interframe region 
between image areas. When copy sheets are to receive an image of the test 
patches, the exposure of the test patches is delayed (or advanced) 
relative to the normal operating cycle of the machine to shift the image 
into the image area. In yet another embodiment wherein the test patches 
are exposed in the interframe region, the copy sheet feeding operation is 
delayed (or advanced) to align the copy sheet with the test patches. 
Whatever the mode for affecting selected alignment of copy sheets with the 
test patches, it may be desirable to provide a special output tray for 
copies having images of the test patches. Such provision has been 
disclosed as a preferred feature of the present invention. 
The invention, and its objects and advantages, will become more apparent in 
the detailed description of the preferred embodiment presented below.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
The Machine Generally 
With reference of FIG. 1, there is shown an electrographic machine 10 
having an image transfer member in the form of a photoconductive belt 12 
trained about rollers. Belt 12 is moved in a clockwise direction, as 
represented by arrow 24. Machine 10 includes an exposure platen 28 against 
which an original document can be positioned in an exposure position for 
copying. Originals are fed to platen 28 by a recirculating document feeder 
30 or by a document positioner 31. Feeder 30 circulates originals in 
sequence from the bottom of a set 34 of originals to exposure platen 28 
and then back up to the top of the set. A more detailed disclosure of the 
operation and structure of feeder 30 is disclosed in commonly-assigned 
U.S. Pat. No. 4,099,860. As an original moves along the path toward platen 
28, a detector 60 generates a count signal which is applied to a logic and 
control unit (LCU) 62. It will be understood that original documents need 
not be hard copy originals, but may also be electronic data. 
An image-producing means 63 includes a pair of flash lamps 46 and 48 for 
illuminating an original document; where upon an image is produced which 
is projected by a mirror 64, a lens 66, and a mirror 68 onto belt 12 at an 
exposure station 70. The magnification of lens 66 is such that light is 
projected over an area on belt 12 defined as an image area, or as a frame, 
which could be, for example, 81/2 inches wide. 
The speed of belt 12 and the timing of flash lamps 46, 48, are controlled 
to locate an image on belt 12 and to provide a suitable interframe 
distance between image areas. In advance of exposure station 70 is a 
charging station 72 for applying an electrostatic charge to belt 12. At 
exposure station 70, the projected light image dissipates the 
electrostatic charge at the exposed areas of the photoconductive belt to 
form a latent electrostatic image on belt 12 corresponding to the image on 
the original. 
The latent electrostatic image on belt 12 is developed with toner at a 
conventional developer station 73. The toner image is then subjected to 
radiation by a post-development erase lamp 75 to reduce the electrical 
stress on photoconductive belt 12 and to reduce the attraction between the 
toner image and belt 12. 
As the toner image on belt 12 approaches a transfer station 74, a copy 
sheet 76 is fed from a supply 78 by a feed roller 80. The copy sheet 76 is 
biased against a registration mechanism 86, which is moved out of the path 
of the copy sheet at the appropriate point in the cycle of machine 10 to 
obtain the desired positioning of sheet 76 relative to an image on belt 
12. 
A transfer station 74 serves as a means to effect the transfer of the toner 
image to copy sheet 76 by (1) applying a charge opposite in polarity to 
that of the toner image and (2) neutralizing the charge on copy sheet so 
that it easily separates from belt 12. The copy sheet bearing toner is 
then passed through a pair of heated fuser rollers 90 and 92. After 
fusing, the copy sheet is transported to an upper output tray 94 or to a 
side output tray 96. Mechanical and electrical cleaning of photoconductive 
belt 12 is effected at a cleaning station 98. 
Timing of the movement of belt 12 in relation to the operation of the 
various elements of machine 10, including feeder 30, is controlled by 
means of a plurality of perforations (not shown) along one of the edges of 
belt 12. As an example, belt 12 can be divided into six image areas by a 
first set of perforations and each image area may be subdivided into 51 
sections by a second set of perforations. The relationship of the two sets 
of perforations to the image area on belt 12 is disclosed in detail in 
commonly-assigned U.S. Pat. No. 3,914,047. At a fixed location along the 
path of movement of belt 12, there is provided a detector 106 for 
detecting belt perforations and for providing timing pulses to LCU 62. An 
encoder 108 is linked to roller 22 and provides a series of timing pulses 
to LCU 62 which are used in conjunction with the pulses from detector 106 
to control the operation of machine 10. 
TEST PATCHES IN INTERFRAME 
Referring to FIG. 2, photoconductive belt 12 is illustrated with a 
plurality of image areas or film frames 110 spaced slightly apart from 
each other along the longitudinal length of the belt; thus defining 
non-image interframe regions 112. 
In order to control the electrographic process, it is known to provide one 
or more test patches 114 of toner in interframe regions 112. The test 
patches can be formed by leaving such areas charged when the other parts 
of the photoconductive belt outside image areas 110 are discharged, and 
then exposing the area to a predetermined level of irradiation. Then toner 
is applied to the test patches by development station 73. In this manner 
the density of toner on the test patches is directly related to the 
density of toner in image areas 110. By way of example, three toned test 
patches 114 are shown adjacent to each other in each interframe region 
112. However, more or fewer control areas could be provided if desired. 
When multiple test patches for each interframe region are used for density 
measurement, the patches preferably are exposed to obtain different 
density levels of toner so that the electrographic process can be checked 
and controlled for various operating parameters. 
As test patches 114 pass erase lamp 75, light rays from the lamp travel 
from the back side of the photoconductive belt and through the test 
patches and toner on the front surface of the belt. A photodetector in the 
form of a small area photodiode 116 is provided closely adjacent the 
surface of the belt for receiving light rays passing through the test 
patches as they are driven between the lamp 32 and the photodetector. 
A signal generated by photodetector 116 is provided to LCU 62, which is 
programmed to provide various feedback signals to portions of the 
apparatus in response to the signal received from the photodetector. For 
example, the control signal from the photodetector can cause the LCU to 
regulate a number of process parameters such as the voltage applied to 
photoconductive belt 12 at charging station 72 and the intensity level of 
lamps 46 and 48 of the exposure station to thereby control the exposure of 
the belt. In general, the signal from photodetector 116 can be used to 
control any process parameter that effects the density of the toner images 
on the photoconductor. 
LOGIC AND CONTROL 
LCU 62 and an operator control panel 118 are shown in greater detail in 
FIG. 3. LCU 62 has a programmable computer, such as a microprocessor, 
which has a stored program responsive to input signals for sequentially 
actuating the various elements of machine 10 as well as for controlling 
the operation of many other functions of machine 10 (as disclosed in 
greater detail in the aforementioned U.S. Pat. No. 3,914,047). Programming 
of commercially available microprocessors, such as Intel Model 8085 (which 
along with others can be used in accordance with the invention), is a 
conventional skill well understood in the art. The following disclosure is 
written to enable a programmer having ordinary skill in the art to produce 
an appropriate control program for the microprocessor. The particular 
details of any such program would, of course, depend on the architecture 
of the designated microprocessor. 
As shown in FIG. 3, LCU 62 includes temporary memory 118 which can be 
provided by Read/Write Memory or Random Access Memory, a central 
processing unit 119, a timing and cycle control unit 120, and a stored 
program control unit 121 which comprises a Read-Only Memory. Data input 
and output are performed sequentially under program control. Input data is 
applied to LCU 62 either through input signal buffers 122 to input data 
latches 123 or through an interrupt signal processor 124. The input 
signals are derived from operator control panel 117, for tiny pulses such 
as those from detector 106 and encoder 108, and from various analog to 
digital converters which process signals from monitoring devices (not 
shown) in machine 10. The output data and control signals are applied to 
output data storage latches 126 which provide inputs to suitable output 
drivers 128 which are connected to various elements of machine 10. 
Operator control panel 117 includes a plurality of operator actuatable 
switches (buttons). For example, a numerical keyboard 130 includes ten 
buttons for "0"-"9" inclusive A "c" button 132 is used to cancel or clear 
the previous instructions fed in from panel 117. A star "*" button 134 is 
actuated by the operator to designate when copy sheets are to contain 
images of test patches. This function will be described in greater detail 
later. A "start" button 136 initiates operation of apparatus 10 and a stop 
button 138 terminates operation of machine 10. 
Machine 10 can be operated in either a noncollate mode or a collate mode. 
In the noncollate mode, the output of machine 10 is sets of uncollated 
copies which may be collated manually or by a sorter (not shown). In the 
collate mode, sets of collated copies are produced. If the noncollate mode 
is desired, a button 140 is depressed; and if the collate mode is desired, 
a button 142 is depressed. In the noncollate mode, each original in the 
set of originals 34 in feeder 30 is fed individually to platen 28 where 
machine 10 makes the number of copies requested by the operator before 
making copies of the next original. On the other hand, in the collate 
mode, each original in a set of originals 34 is sequentially copied, and 
the set of originals 34 is recyled until the number of copies requested is 
completed. Button 158 is actuated to effect output of copies to side 
output tray 96, while button 160 is actuated to effect output of copies to 
upper output tray 94. A display 162 shows messages indicating to the 
operator various conditions which occur in machine 10, for example, the 
mode the machine is operating in, what action should be taken next, where 
jams may be located, etc. 
OPERATION 
With reference to FIGS. 4 through 6, the operation of machine 10 will now 
be described in accordance with the present invention in which test 
patches are selectively printed on copy sheets. In FIG. 4, there is shown 
a flow chart for a patch set-up mode. To enter the Patch set-up mode, the 
operator must press 888* on panel 117, whereupon the operator will be 
prompted with an introductory message on display 162 "PATCH PRINTING MODE, 
PRESS * FOR SELECTIONS, OR STOP TO EDIT." The operator uses "*" button 134 
to scroll through the various patch printing modes available. When the 
desired mode is displayed, a "select" button 149 is pushed to select that 
particular mode. 
Thus, as shown in FIG. 4, the operator enters the patch mode by entering 
888*. The operator is asked if patches are required on all copies. If so, 
select button 149 is pushed. Referring to FIG. 5, the operator may next 
select an exit tray and start copying. During the copy cycles, the machine 
timing is adjusted to produce copies with test patches thereon. The timing 
adjustments will be discussed hereinafter. 
If the operator does not desire test patches on all copies, he or she 
pushes "*" button 134 (rather than "select" button 149) when asked if 
patches are required on all copies. The operator will next be asked for 
the exit tray for copies without patches, and for the exit tray for test 
copies with patches (see FIG. 6). 
MACHINE TIMING 
There are several ways to adjust machine timing so that the test patches, 
which are normally located in the image interframe region of belt 12. Some 
of those ways are: 
1. Advance or delay the exposure of the original document and the test 
patches sufficiently to shift the images thereof on belt 12; 
2. Advance or delay the feeding of copy sheets 76 by registration means 86; 
3. Advance or delay the exposure of only the test patches to shift the 
image thereof in image areas 110, provision being made to inhibit 
discharging the belt by the original document in the area of the test 
patch image; and 
4. Various combinations of the above. 
TEST PATCHES IN MARGIN 
Whereas FIG. 2 depicts a photoconductive belt having test patches in the 
interframe region between image areas, FIG. 7 shows a similar 
photoconductive belt 12' having test patches 114' in the cross-track 
margin region laterally outside of image areas 110'. As such, adjusting 
machine timing as described hereinbefore would not affect a repositioning 
of the copy sheets relative to the test patches such that the copy sheets 
would align with the patches. Accordingly, I have schematically shown a 
mechanism 170 in FIGS. 8 and 9 for selectively shifting the copy sheets 
cross track when copies are to include test patches. 
Mechanism 170 is positioned in the feed path of copy sheets 76, and 
includes a plate 172 with a first set of idler rollers 174 aligned with 
the path of copy sheets 76 and a second set of idler rollers 176 set at an 
angle to the direction of incoming copy sheets. Plate 172 can be rocked 
about an axis 178 so that either rollers 174 or 176 contact a drive 
cylinder 180, as shown in FIG. 9. If rollers 174 are driven, copy sheets 
are moved along the feed path to transfer station 74 without deviation so 
as to align with image areas 110' of belt 12'. When copy sheets are to 
receive test particles as determined by LCU 62, plate 172 is rocked to its 
broken line position of FIG. 9 so that rollers 176 are driven. Now, 
advancing copy sheets are shifted laterally as they are fed to the 
transfer station. The copy sheets are shifted cross track relative to belt 
12' so as to overlie the test patches. The logic flow diagram of FIGS. 4-6 
are applicable also to the embodiment of FIGS. 7-9, except that each 
operation labeled "adjust machine timing" would be entitled instead "align 
copy sheets cross track." 
This 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.